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Signs and Symptoms
About 30% of persons have no signs or symptoms and signs and symptoms are less common in children than adults. Signs and symptoms include:
- abdominal pain
- loss of appetite
- nausea and vomiting
- joint pain
Who's at Risk?
- Persons with multiple sex partners or a diagnosis of a sexually transmitted disease.
- Men who have sex with men.
- Sexual contacts of infected persons
- Injection drug users
- Household contacts of chronically infected persons.
- Infants born to infected mothers.
- Infants/children of immigrants from areas with high rates of HBV infection.
- Health care and public safety workers
- Hemodialysis patients
How is Hepatitis B Spread from Person to Person?
Hepatitis B spreads from person to person by:
- blood or body fluids from an infected person entering the body of a person who is not immune to hepatitis b;
- having sex with an infected person without using a condom
- sharing needles or "works" when "shooting" drugs
- through needlesticks or sharps exposures on the job
- or from an infected mother to her baby during birth.
How Can the Spread of Hepatitis B be Prevented?
- getting the hepatitis b vaccine
- using latex condoms correctly and every time you have sex
- do not shoot drugs; if you shoot drugs, stop and get into a treatment program; if you can't stop, never share needles, syringes, water, or "works", and get vaccinated against hepatitis A and B
- do not share personal care items that might have blood on them (razors, toothbrushes)
- if you are a health care or public safety worker, get vaccinated against hepatitis B, and always follow routine barrier precautions and safely handle needles and other sharps.
How is Hepatitis B Treated
Source: Information provided by the Centers for Disease Control and Prevention, 2001.
- Hepatitis B infected persons should be evaluated by their doctor for liver disease and offered medication regimens specifically developed for the treatment of Hepatitis B. |
FO19 Protected forests
Most of Finland's protected forests are located in the northern part of the country, which is mainly covered by north boreal forest vegetation zone. According to preliminary data, a quarter of all forest land is currently protected there, some areas more strictly than others. Largest in area are protected areas on state land as well as wilderness areas, which are also established on state land. Each of them covers almost 10% of all forest land. Elsewhere in Finland protected areas are more sparse. The share of protected areas in middle boreal forest vegetation zone is approximately 3% and in south and hemiboreal zone less than 2%. The share of protected areas on privately owned land increases towards south.
Strictly protected forests are areas where no forestry is practiced. According to current evaluation these areas cover 4.3% of all forest land in Finland. The proportion of strictly protected forests varies regionally, however. In north boreal forest vegetation zone the share of strictly protected forests is greatest, almost 10% of all forest land. In southern Finland the share of protected forests is small, varying between 1.8% and 0.8%.
Impact on biodiversity
Forest species become threatened primarily as a result of decreases in the amount and quality of habitats (see also FO13 and FO14). Establishment of protected areas aims above all in conserving the diversity of forests. Most often this comes true in pristine forests, where tree ages are variable and species composition corresponds to the age of the forest as well as soil type.
Diversity of large pristine forests is increased by natural disturbances such as fires, storms, activities of certain mammals as well as many diseases and pests. As a result of disturbance the structure of the forest changes. For example, falling trees create new gaps to the forest canopy and also increase the amount of dead wood, which is essential for several species (see also FO6). Various disturbances create a diverse mosaic of habitats and thus increase species richness.
In addition to the total amount of protected areas, the size of individual reserves and their connectivity to each other are important. The management of forestry land outside the protected areas also affects their ability to support high species richness. For example many species which nest solely in protected areas, may still be able to feed in and migrate through suitable commercial forests.
All protected forests are not entirely pristine forests. Especially in southern Finland new reserves have been established in commercial forests, which may not reach natural state for decades. The development can, however, be enhanced by restoration and management (FO20).
|The frequency of updates of this indicator is unknown for the time being.|
- Updated (14.05.2013) |
In GCSE Science students will look at the requirements for keeping healthy. This is the fourth of six quizzes on that topic and it looks at the natural defences of the body against infection, such as white blood cells, antibodies, mucus, stomach acid and tears.
The human body is well defended against infection. Sometimes pathogens like bacteria and viruses do get through, making you ill. There are physical barriers like your skin and the cilia (tiny moving hairs) and mucus that line your respiratory system. The mucus is sticky and traps bacteria and viruses that enter your nose as you breathe in. There are chemical barriers too such as enzymes in tears and saliva that break down pathogens.
When the pathogens do get past the first line of your body's defences, the second line is the white blood cells. There are several different types of these each working in a different way. Some of them engulf (surround) the pathogen and secrete enzymes that digest the bacteria, virus or single celled organism that has arrived in your body. Others neutralise any toxins that enter the bloodstream from the infection. Another type of white blood cell produces antibodies that react to a specific pathogen that enters your bloodstream. These antibodies then either damage the pathogen, making it harmless, or label it so that other cells can find and destroy it.
The white blood cells that produce the antibodies remain in your bloodstream so that the next time the pathogen gets into your body, it can immediately be tackled. They give you an immunity to disease. This natural defence can also be introduced artificially by vaccination. Some diseases are very harmful to the human body, for example, polio. This terrible disease left many children unable to walk properly until a vaccine was found. Nowadays children are vaccinated well before they can develop polio and it is virtually unknown in developed countries with a good health system.
But despite your natural defences, infections do get through. If you eat a properly balanced diet and exercise regularly, your immune system will work well against invading microorganisms.
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This majestic view taken by NASA's Spitzer Space Telescope tells an untold story of life and death in the Eagle nebula, an industrious star-making factory located 7,000 light-years away in the Serpens constellation. The image shows the region's entire network of turbulent clouds and newborn stars in infrared light. The color green denotes cooler towers and fields of dust. Red represents hotter dust thought to have been warmed by the explosion of a massive star about 8,000 to 9,000 years ago. NASA/JPL-Caltech/STS cI/ Institut d'Astrophysique Spatiale
In its first glimpse of the heavens following the successful December 1999 servicing mission, NASA's Hubble Space Telescope captured a majestic view of a planetary nebula, the glowing remains of a dying, Sun-like star. This stellar relic, first spied by William Herschel in 1787, is nicknamed the "Eskimo" Nebula (NGC 2392) because, when viewed through ground-based telescopes, it resembles a face surrounded by a fur parka. NASA
While anchored to a foot restraint on the end of the Orbiter Boom Sensor System, astronaut Scott Parazynski, STS-120 mission specialist, assesses his repair work as the solar array is fully deployed during the mission's fourth session of extravehicular activity while Space Shuttle Discovery is docked with the International Space Station. NASA
Recent Cassini images of Saturn's moon Enceladus backlit by the sun show the fountain-like sources of the fine spray of material that towers over the south polar region. NASA/JPL/Space Science Institute
This artist concept illustrates how a massive collision of objects, perhaps as large as the dwarf planet Pluto, smashed together to create the dust ring around the nearby star Vega. New observations from NASA's Spitzer Space Telescope indicate the collision took place within the last one million years. Astronomers think that embryonic planets smashed together, shattered into pieces, and repeatedly crashed into other fragments to create ever finer debris. NASA/JPL-Caltech/T. Pyle (SSC)
Approximately 120 miles above the Martian surface, a nuclear thermal propulsion transfer vehicle and the ascent stage of a two-stage Mars lander prepare to rendezvous in this concept painting by Pat Rawlings. The vehicle's nuclear reactors also serve as the primary onboard electrical power source with solar arrays providing backup power. Looming behind the spacecraft, the enormous shield volcano, Ascraeus Mons, rises through early morning clouds with the caldera at its peak eventually reaching above Mars' tenuous atmosphere. Pat Rawlings/SAIC/NASA
Launched on July 26, 2005 from the Kennedy Space Center in Florida, STS-114 was classified as Logistics Flight 1. Among the Station-related activities of the mission were the delivery of new supplies and the replacement of one of the orbital outpost's Control Moment Gyroscopes. NASA
This artist's concept depicts the pulsar planet system discovered by Aleksander Wolszczan in 1992. Wolszczan used the Arecibo radio telescope in Puerto Rico to find three planets - the first of any kind ever found outside our solar system - circling a pulsar called PSR B1257+12. Pulsars are rapidly rotating neutron stars, which are the collapsed cores of exploded massive stars. NASA/JPL-Caltech/R. Hurt (SSC)
This image is one of the largest panoramic images ever taken with Hubble's cameras. It is a 50-light-year-wide view of the central region of the Carina Nebula where a maelstrom of star birth — and death — is taking place. This image is a mosaic of the Carina Nebula assembled from 48 frames taken with Hubble's Advanced Camera for Surveys. NASA/ESA/N. Smith/University of California/The Hubble Heritage/STScI/AURA
This artist's concept illustrates one possible answer to the puzzle of the "giant galactic blobs." These blobs (red), first identified about five years ago, are mammoth clouds of intensely glowing material that surround distant galaxies (white). Astronomers using visible-light telescopes can see the glow of the blobs, but they didn't know what provides the energy to light them up. NASA/JPL-Caltech/R. Hurt (SSC)
One hundred years ago today, the Japanese Empire declared war on Germany, turning the previously Europe-centric conflict into a truly 'World War.'
ByThe Monitor's European Bureau
The Christian Science Monitor, ProQuest
These articles originally ran in The Christian Science Monitor on Aug. 24, 1914. The Japanese Empire had been an ally of Britain since 1902, and with the start of World War I, was eying Germany's holdings in what is now Shandong Province, China. On Aug. 14, 1914, Japan sent Germany an ultimatum which went ignored. On Aug. 23, Japan officially declared war on Germany, turning the previously Europe-centric conflict into a truly "World War." |
|This article needs additional citations for verification. (July 2009)|
A salt dome is a type of structural dome formed when a thick bed of evaporite minerals (mainly salt, or halite) found at depth intrudes vertically into surrounding rock strata, forming a diapir. It is important in petroleum geology because salt structures are impermeable and can lead to the formation of a stratigraphic trap.
The formation of a salt dome begins with the deposition of salt in a restricted marine basin. Because the flow of salt-rich seawater into the basin is not balanced by outflow, the only water lost from the basin is via evaporation, resulting in the precipitation and deposition of salt evaporites. The rate of sedimentation of salt is significantly larger than the rate of sedimentation of clastics, but it is recognised that a single evaporation event is rarely enough to produce the vast quantities of salt needed to form a layer thick enough for salt diapirs to be formed. This indicates that a sustained period of episodic flooding and evaporation of the basin must occur, as can be seen from the example of the Mediterranean Messinian salinity crisis. At the present day, evaporite deposits can be seen accumulating in basins that merely have restricted access but do not completely dry out; they provide an analogue to some deposits recognised in the geological record, such as the Garabogazköl basin in Turkmenistan.
Over time, the layer of salt is covered with deposited sediment, becoming buried under an increasingly large overburden. The overlying sediment will undergo compaction, causing an increase in density and therefore a decrease in buoyancy. Unlike clastics, pressure has a significantly smaller effect on the density of salt due to its crystal structure and this eventually leads to it becoming more buoyant than the sediment above it. The ductility of salt initially allows it to plastically deform and flow laterally, decoupling the overlying sediment from the underlying sediment. Since the salt has a larger buoyancy than the sediment above - and if a significant faulting event affects the lower surface of the salt - the salt can begin to flow vertically, forming a salt pillow. The vertical growth of these salt pillows creates pressure on the upward surface, causing extension and faulting. (see salt tectonics).
Eventually, over millions of years, the salt will pierce and break through the overlying sediment, first as a dome-shaped and then a mushroom-shaped - fully formed salt diapir. If the rising salt diapir breaches the surface, it can become a flowing salt glacier. In cross section, these large domes may be anywhere from 1 to 10 kilometres (0.62 to 6.2 mi) across, and extend as deep as 6.5 kilometres (4.0 mi).
Major occurrences of salt domes are found along the Gulf Coast of the USA in Texas and Louisiana. One example of an island formed by a salt dome is Avery Island in Louisiana. At present ocean levels it is no longer surrounded by the sea but it is surrounded by bayous on all sides.
Another example of an emergent salt dome is at Onion Creek, Utah / Fisher Towers near Moab, Utah, U.S. These two images show a Cretaceous age salt body that has risen as a ridge through several hundred meters of overburden, predominantly sandstone. As the salt body rose, the overburden formed an anticline (arching upward along its centerline) which fractured and eroded to expose the salt body.
The term "salt dome" is also sometimes inaccurately used to refer to dome-shaped silos used to store rock salt for melting snow on highways. These domes are actually called monolithic domes and are used to store a variety of bulk goods.
The rock salt that is found in salt domes is mostly impermeable. As the salt moves up towards the surface, it can penetrate and/or bend strata of existing rock with it. As these strata are penetrated, they are generally bent slightly upwards at the point of contact with the dome, and can form pockets where petroleum and natural gas can collect between impermeable strata of rock and the salt. The strata immediately above the dome that are not penetrated are pushed upward, creating a dome-like reservoir above the salt where petroleum can also gather. These oil pools can eventually be extracted, and indeed form a major source of the petroleum produced along the coast of the Gulf of Mexico.
Other uses include storing oil, natural gas, hydrogen gas, or even hazardous waste in large caverns formed after salt mining, as well as excavating the domes themselves for uses in everything from table salt to the granular material used to prevent roadways from icing over.
- Plasticity (physics)
- Salt tectonics
- Strategic Petroleum Reserve
- Underground hydrogen storage
- Structural trap
- Schreiber, B.C. and Hsü, K.J. (1980) Evaporites. In Developments in Petroleum Geology, Vol. 2 (Ed. G.D. Hobson), pp. 87–138. Elsevier Science, Amsterdam.
- RGD 1993. Geological Atlas of the subsurface of The Netherlands: Explanations to map sheet IV Texel-Purmerend (1:250,000). Rijks Geologische Dienst (Haarlem): 127 pp.
- Dronkert, H. & Remmelts, G. 1996. Influence of salt structures on reservoir rocks in Block L2, Dutch continental shelf. In: Rondeel, H.E., Batjes, D.A.J., Nieuwenhuijs, W.H. (eds): Geology of gas and oil under the Netherlands, Kluwer (Dordrecht): 159–166.
- C.Michael Hogan. 2011. Sulfur. Encyclopedia of Earth, eds. A.Jorgensen and C.J.Cleveland, National Council for Science and the environment, Washington DC
- Salt dome formation
- Salt dome at Schlumberger's Oilfield Glossary
|Wikimedia Commons has media related to Salt domes.| |
Scoliosis is a medical condition characterized by an abnormal sideways curvature of the spine. It can occur during growth spurts in childhood or adolescence, or it can be caused by underlying conditions. Scoliosis can range from mild to severe and may require treatment to manage symptoms and prevent further progression.
The most common symptom of scoliosis is an abnormal curvature of the spine. Other symptoms may include:
- Uneven shoulder or hip levels.
- Asymmetrical waistline or rib cage.
- One shoulder blade appearing more prominent than the other.
- Back pain or discomfort, particularly after prolonged periods of standing or sitting.
- Fatigue or muscle stiffness.
Diagnosing scoliosis involves a thorough examination by healthcare professionals, typically orthopedic specialists or spine surgeons. They will evaluate the curvature of the spine using physical examination techniques, such as the Adam’s Forward Bend Test. Imaging tests, such as X-rays or MRI scans, may be performed to determine the severity and extent of the curvature. Additionally, the healthcare provider may measure the degree of the curvature using a system called the Cobb angle.
The treatment for scoliosis depends on various factors, including the severity of the curvature, the age of the individual, and the potential for further progression. Treatment options may include:
Observation: In cases of mild scoliosis with minimal progression, regular monitoring may be recommended, especially if the individual is still growing.
Bracing: For moderate scoliosis or if the individual is still growing, bracing may be prescribed. The brace helps slow down or prevent further progression of the curvature by providing external support to the spine.
Physical Therapy and Exercises: Certain exercises and physical therapy techniques can help improve posture, strengthen muscles, and maintain flexibility. These exercises are often tailored to the individual’s specific curvature and overall condition.
Surgical Intervention: In severe cases of scoliosis or when other treatments have been unsuccessful, surgery may be recommended. The surgery aims to straighten and stabilize the spine using techniques such as spinal fusion or the insertion of rods or screws.
Living with scoliosis may involve making certain lifestyle adjustments:
Maintaining Good Posture: Practicing good posture and body mechanics can help minimize discomfort and prevent additional strain on the spine.
Regular Exercise: Engaging in regular physical activity, with guidance from healthcare professionals, can help strengthen the muscles that support the spine and improve overall fitness.
Pain Management: If scoliosis causes back pain or discomfort, various pain management techniques, such as applying heat or cold packs, taking over-the-counter pain relievers, or receiving physical therapy, may help alleviate symptoms.
Emotional Support: Living with scoliosis can have emotional and psychological impacts. Seeking support from loved ones, joining support groups, or engaging in counseling can provide valuable emotional support and coping strategies.
Regular Monitoring: Regular check-ups with healthcare professionals are important to monitor the progression of scoliosis, evaluate treatment effectiveness, and address any new concerns.
Remember, the management of scoliosis is individualized, and healthcare professionals will tailor the treatment plan based on the specific needs and circumstances of each individual. With appropriate care, support, and lifestyle adjustments, individuals with scoliosis can lead active and fulfilling lives. |
9. Application of the theory of generations (X, Y, Z)
In the early 1990s, the American historian William Strauss and the economist Neil Howe developed the "theory of generations". The scientists have put forward the theory that people born at different times are different from each other. In particular, the peculiarities of the perception of information and assimilation of educational material differ. Currently, 3 generations are socially active: generation X (born 1964-1984), generation Y (born 1985-2003), and generation Z (born 2004-2023) Generation X (born 1964-1984)
Representatives of this generation are easy to learn and have sufficient competence and experience. Their disadvantage: about 80% of representatives have difficulty with new technologies.
The preferred form of study is full-time. If we talk about e-learning, they would prefer classic electronic manuals. Generation Y (born 1985-2003)
They are easy to learn, have good computer skills, can give reasoned answers, and are accustomed to searching for information on their own. They do not have a generalized approach to gaining knowledge, with them, you can apply different approaches to learning: online courses in the format of "quest", webinars, computer simulators, and much more.
Generation Y will prefer distance learning to full-time learning. Generation Z (born 2004 - 2023)
They are the representatives of the modern digital world, and actively use the Internet and gadgets. They are used to having information available in one click. They switch attention quickly and don't concentrate well, but they absorb information well.
When teaching representatives of Generation Z, one should:
- Allow studying on a free schedule.
- Use microlearning.
- Include game techniques in training. |
This is a native North American species, widely distributed throughout the southern half of the three Prairie Provinces.
Leaf, Trunk, Soil
Damage, symptoms and biology
The spring cankerworm is a defoliator of many deciduous trees and shrubs in various types of rural and urban tree stands and plantings.
Damage usually begins in late May when young larvae chew small holes in the developing leaves. As feeding continues, these holes gradually enlarge until only the larger leaf veins and midribs remain. When cankerworm populations are large, starving larvae in search of food may drop on silken threads and become a nuisance around homes or in well-used areas. During outbreaks lasting from 1 to 4 years, trees may be completely defoliated; however, most trees usually refoliate in July, 3–5 weeks after the first attack.
Three or more consecutive years of severe defoliation may cause many of the upper branches to die and affect tree appearance. Severe defoliation may also contribute to tree mortality.
The spring cankerworm has a 1-year life cycle. The larvae are slender and move with a looping motion. The mature larvae overwinter in the soil and pupate in the very early spring. Adult wingless females and winged males soon emerge to mate, and the females climb host trees and shrubs, where they lay eggs in clusters on the stems and lower branches. Mature spring cankerworm larvae are about 20–30 mm long, and they vary in colour from yellowish green to almost black, with a mottled appearance.
A number of natural agents may control cankerworm populations. Parasitic insects attack the egg, larval, and pupal stages of cankerworm life cycles, while other predators (insects, spiders, birds, and small rodents) may attack all the stages. Cold winter temperatures, late spring frosts, starvation, or disease may also cause the collapse of larval populations.
Canadian Forest Service Publications
Diet and feeding behaviour
: Feeds on the leaves of plants.
- Free-living defoliator: Feeds on and moves about freely on foliage.
Information on host(s)
The preferred hosts of the spring cankerworm is Siberian elm but it also attacks ash, basswood, bur oak, Siberian elm, aspen, white birch, and various fruit trees. The spring cankerworm attacks many of the same trees as the fall cankerworm, but prefers Siberian elm.
American mountain-ash, ashes, basswood, black ash, blue ash, bur oak, common prickly-ash, European ash, European mountain-ash, fruit trees, green ash, mountain-ash, northern red ash, Oregon ash, pumpkin ash, siberian elm, Sitka mountain-ash, trembling aspen, white ash, white birch |
About Epidemiology - what is it and what do these numbers really mean?
Epidemiology - what is it and what do these numbers really mean?
Instructor: Andreea Dobrescu
The COVID-19 pandemic increased the public’s familiarity with the word ‘epidemiology’ to a unparalleled during previous public health events. Epidemiology is one of the scientific disciplines of public health with sound methods of scientific inquiry at its foundation. It is essential to the fight against any disease. Its central paradigm is that analysis of population patterns of disease, particularly by linking these to exposure variables (risk factors), provides understanding of their causes. Epidemiology is useful in other ways, including preventing and controlling disease in populations and guiding health and health-care policy and planning.
This webinar gives an introduction into the large toolbox of epidemiological data, methods and approaches to disease investigations.
- Introduction to Epidemiology
Key features and applications of descriptive and analytic epidemiology
- Summarizing Data (optional)
Calculation and interpretation of mean, median, mode, ranges, variance, standard deviation, and p-value
- Measures of Risk
Calculation and interpretation of ratios, proportions, incidence rates, mortality rates, prevalence, fatality rate, herd immunity and Reproduction (R) value,
- Displaying Public Health Data
Preparation and application of tables, graphs, and charts such as arithmetic-scale line, histograms, pie chart, and box plot
- Public Health Surveillance
Processes, uses, and evaluation of public health surveillance
- Investigating an Outbreak
Steps of an outbreak investigation
After this course the participant
- knows key features and applications of epidemiology
- is able to calculate and interpret epidemiological effect estimates
- understands processes, uses, and evaluation of public health surveillance
- knows the steps of an outbreak investigation |
COPD stands for chronic obstructive pulmonary disease. Emphysema is a form of COPD.
- COPD is a group of diseases that cause damage to the lungs and restrict their ability to obtain oxygen, restricting oxygen flow in the blood.
- Medical and rehabilitation programs and therapy are available to patients with COPD to help them combat their symptoms
- Surgical treatments for COPD include lung volume reduction surgery and lung transplantation
Over 15 million Americans have been diagnosed with COPD. Evidence suggests that another 15 million have COPD but remain undiagnosed. COPD is presently the third leading cause of death in this country and the 2nd leading cause of disability.
Most COPD is related to cigarette smoking, but recent evidence suggests that 25% of those with COPD never smoked. Increasingly environmental factors are felt to play a role in the development and worsening of COPD. There is also an inherited form of COPD called alpha-1 antitrypsin deficiency.
All COPD is not the same. There are those with more of a chronic bronchitic form of COPD and some with a more emphysematous form, meaning it is related to emphysema.
Emphysema is a progressive, destructive lung disease in which the walls between the tiny air sacs are damaged. As a result, the lungs lose their elasticity causing exhalation, or breathing out, to become more and more difficult. Air remains trapped in the overinflated lungs, leading to progressive shortness of breath.
COPD and asthma are both obstructive lung diseases marked by shortness of breath but asthma is by definition reversible while with COPD the airflow obstruction is either irreversible or only partly reversible. The mainstay of therapy in asthma is inhaled corticosteroids while in COPD it is long acting bronchodilators. Over time some asthmatics may develop an irreversible component, a variant of COPD. Because both are common diseases they can occur together. Estimates suggest that as many as 20% of COPD patients have ACOS, the asthma/COPD overlap.
Treating and preventing exacerbations—or flares of disease—are critical factors in managing COPD. People with frequent exacerbations (2 or more a year), have a more rapid deterioration in lung function, more frequent hospitalizations, and higher mortality.
There are many medical options for treating emphysema/COPD.
- The primary recommendation for preventing and treating COPD is to stop smoking.
- Bronchodilators relax the muscles of the bronchi, the major air passageway in the lungs. This allows air to get in and out easier. These medications are available in pill or liquid form (taken orally), or as an aerosol spray (inhaled).
- Steroids are powerful anti-inflammatory medications. The only role for systemic steroid therapy in COPD is for 5-10 days during an acute exacerbation. Longer term treatment with systemic steroids in COPD has not been shown to have any benefit and can carry significant risks. The potential side effects of long term systemic steroid use include osteoporosis, diabetes, weight gain, cataracts, muscle weakness, cataracts, and hypertension.
- Antibiotics are frequently used during acute bronchitis to fight bacterial infections. Flu and pneumonia vaccinations are recommended for all patients with COPD. The influenza shot is administered yearly while the pneumonia shot is administered every five years.
- Oxygen therapy in patients with a resting O2 saturations less than or equal to 88% has been shown to improve quality of life and survival.
- Proper nutrition is critical for emphysema patients. Weight loss, which is common in patients with advanced emphysema, can be caused by inadequate food intake in individuals too short of breath to eat. However, most weight loss in COPD patients is due to the increased metabolic demand of respiratory muscles that are overworked because of emphysema damage.
Pulmonary rehabilitation has clear benefits for patients with COPD. Exercise increases endurance, improves shortness of breath, increases maximal oxygen consumption, and improves quality of life. Numerous studies have documented improvement in symptoms, maximum oxygen consumption, and quality-of-life measures. A decrease in the number of hospitalizations has also been shown in patients who participate in pulmonary rehabilitation programs.
Benefits do vary among individuals, however, and consistent participation in an exercise regimen is necessary to maintain improvements. In addition, it has not been shown that pulmonary rehabilitation produces any change in pulmonary function tests (PFTs) or overall oxygen requirements for individuals.
If medical treatment does not alleviate the symptoms of COPD, or symptoms and exacerbations increase, surgery may be an option. However, in order to be a candidate for surgery, there are specific criteria. These include not being a current smoker, participating in a pulmonary rehabilitation program, and being strong enough to receive surgery.
There are two types of surgery performed for COPD, Lung Volume Reduction Surgery and Bullectomy.
- Lung Volume Reduction Surgery involves removing parts of the lung that are most affected by COPD. Removal of lung tissue seems counterintuitive, but it allows the remaining, healthy parts of the lung function more efficiently.
- Bullectomy involves the removal of bullae from the lungs. Bullae are large air sacs in the lungs that form when a large number of alveoli are destroyed by COPD. These air sacs interfere with breathing.
If damage to the lungs is too severe or surgery does not alleviate symptoms, a doctor may recommend a lung transplant.
If you need help for a lung or chest issue, we’re here for you. Call (212) 305-5501 or request an appointment online to get started today. |
Gene editing is a remarkable technology that has captured the imagination of scientists and the public alike. At the forefront of this genetic revolution is a tool called CRISPR-Cas9. It may sound complex, but its power lies in its simplicity. CRISPR-Cas9 has the potential to reshape the future of medicine, agriculture, and biotechnology, offering solutions to genetic challenges that were once thought impossible to tackle.
CRISPR, which stands for Clustered Regularly Interspaced Short Palindromic Repeats, is like nature’s ancient immune system stored within certain bacteria. It helps them fend off viruses by remembering past encounters. Cas9, on the other hand, acts as the precision scissors of this genetic tool, capable of making precise cuts in DNA. Together, they form a dynamic duo, enabling scientists to edit genes with unprecedented accuracy.
In this article, we’ll take a journey into the world of CRISPR-Cas9, unraveling its basic mechanics, exploring its wide-ranging applications, and delving into the ethical questions it raises. Join us as we demystify this gene editing marvel and understand how it’s poised to shape the future of genetics in ways we could only dream of before.
Table of Contents
The Basics of CRISPR-Cas9
Exploring the CRISPR Acronym
CRISPR, which stands for Clustered Regularly Interspaced Short Palindromic Repeats, is a mouthful of a name for a fascinating genetic tool. Imagine it as nature’s way of equipping certain bacteria with a defense mechanism against invading viruses. These bacteria store snippets of DNA from past virus encounters within their own DNA, creating a sort of genetic memory. When a virus attacks again, the bacteria use these stored sequences to recognize and fend off the threat.
The Role of Cas9 in Gene Editing
Now, let’s meet Cas9, the molecular scissors of the CRISPR-Cas9 system. Cas9, an enzyme, acts with utmost precision, cutting DNA at specific locations. But it doesn’t act alone; it relies on a guide RNA (gRNA) to pinpoint the exact spot to cut. This duo, Cas9, and gRNA, is like a team of surgeons with a GPS, ensuring they snip the right piece of DNA with remarkable accuracy. Once the cut is made, the cell’s natural repair mechanisms come into play, allowing scientists to introduce desired changes to the DNA.
CRISPR-Cas9 Mechanics: How Does It Work?
Designing Custom gRNA
Creating a custom gRNA is like programming the CRISPR-Cas9 system to target a specific gene. Scientists design this RNA to match the DNA sequence they want to modify, sort of like a genetic “wanted” poster. This gRNA acts as a guide, leading Cas9 to the precise spot in the DNA.
Cas9 Binding and Target Recognition
Once the Cas9 enzyme is armed with the custom gRNA, it becomes a molecular GPS, searching the cell’s DNA for the sequence specified in the gRNA. When it finds a match, Cas9 latches onto the DNA like a key fitting into a lock, ensuring it’s right where it needs to be.
Precision DNA Cleavage
With its target in sight, Cas9 acts as the molecular scissors, cutting the DNA at that exact location. This cut serves as the starting point for the cell’s natural DNA repair mechanisms to kick in.
Leveraging Cellular DNA Repair
Cells have their own repair crews for DNA damage. When Cas9 makes the cut, the cell’s repair machinery swoops in to fix it. Scientists can use this process to introduce changes, such as correcting genetic mutations or adding new genetic information.
Applications of CRISPR-Cas9
Gene Editing in Medicine
CRISPR-Cas9 has immense potential in medicine. Researchers are exploring its use to correct genetic disorders by GENE editing out harmful mutations. This technology could offer hope to patients with conditions like cystic fibrosis and sickle cell anemia.
CRISPR-Cas9 in Agriculture
In agriculture, CRISPR-Cas9 is a game-changer. It allows scientists to develop crops with desirable traits, such as resistance to pests and diseases. This means more efficient and sustainable food production to feed a growing global population.
Beyond medicine and agriculture, CRISPR-Cas9 has numerous biotechnological applications. It’s used to engineer microorganisms for tasks like producing biofuels, pharmaceuticals, and industrial enzymes. This versatility opens doors to various industries.
CRISPR-Cas9’s Role in Scientific Research
Scientists love CRISPR-Cas9 for its ability to precisely edit genes. It’s a powerful tool for understanding gene function and studying diseases in the lab. By “knocking out” or modifying genes, researchers gain valuable insights into the inner workings of biology.
The Ethical and Moral Dilemmas
Ethical Considerations in Gene Editing
As with any groundbreaking technology, CRISPR-Cas9 raises ethical questions. Should we edit the human germline? What about unintended consequences? Ethicists, scientists, and policymakers grapple with these complex dilemmas.
Regulatory Frameworks and Guidelines
To navigate these ethical waters, regulatory frameworks and guidelines are essential. Governments and international bodies are working to establish rules and standards for the responsible use of CRISPR-Cas9.
CRISPR-Cas9: Shaping the Future of Genetics
Current Research and Future Possibilities
CRISPR-Cas9 is far from a finished story. Ongoing research seeks to improve its precision and reduce off-target effects. Meanwhile, scientists dream of tackling previously untreatable gene editing diseases.
Potential Impacts on Human Health and Beyond
The potential impacts of CRISPR-Cas9 reach far and wide. From medicine to agriculture and beyond, this technology has the power to shape our genetic future. However, with great power comes great responsibility, and ethical and regulatory considerations will play a vital role in determining how CRISPR-Cas9 shapes the future of genetics.
What is CRISPR-Cas9?
CRISPR-Cas9 is a gene editing technology that allows scientists to make precise changes to an organism’s DNA.
How does CRISPR-Cas9 work?
CRISPR-Cas9 works by using a molecule called Cas9, guided by a custom RNA sequence, to cut DNA at a specific location, enabling targeted genetic modifications.
What are the applications of CRISPR-Cas9?
CRISPR-Cas9 has diverse applications, including genetic disease treatment, crop improvement, biotechnology advancements, and scientific research.
Are there ethical concerns with CRISPR-Cas9?
Yes, ethical concerns exist, particularly regarding the potential misuse of gene editing technology and its impact on future generations.
Is CRISPR-Cas9 already in use?
Yes, CRISPR-Cas9 is actively used in laboratories worldwide for various research and development purposes, but its widespread clinical use is still evolving.
CRISPR-Cas9 is not just a scientific term; it’s a revolutionary tool that holds incredible promise for the future. We’ve seen how it works, with Cas9 acting like precision scissors, guided by a customized gRNA, to edit gene editing with pinpoint accuracy. Its applications are vast, from medicine to agriculture and biotechnology, offering solutions to genetic challenges we once thought were insurmountable.
As we explore the world of CRISPR-Cas9, it’s important to remember the ethical considerations that come with such a powerful tool. Questions about the responsible use of gene editing and its potential consequences are essential discussions we must continue to have.
In the end, CRISPR-Cas9 is a testament to human ingenuity and our ability to harness the power of nature for the betterment of our world. Its future is bright, and as scientists, ethicists, and society at large grapple with its implications, we’re on the cusp of unlocking new possibilities and shaping the genetic landscape in ways we could only imagine. |
ACID is acronym of Atomicity, Consistency, Isolation and Durability
Atomicity requires that database modifications must follow an all or nothing rule. Each transaction is said to be atomic if when one part of the transaction fails, the entire transaction fails and database state is left unchanged. It is critical that the database management system maintains the atomic nature of transactions in spite of any application, DBMS, operating system or hardware failure.
An atomic transaction cannot be subdivided, and must be processed in its entirety or not at all. Atomicity means that users do not have to worry about the effect of incomplete transactions.
Transactions can fail for several kinds of reasons:
- Hardware failure: A disk drive fails, preventing some of the transaction’s database changes from taking effect
- System failure: The user loses their connection to the application before providing all necessary information
- Database failure: E.g., the database runs out of room to hold additional data
- Application failure: The application attempts to post data that violates a rule that the database itself enforces, such as attempting to create a new account without supplying an account number
The consistency property ensures that the database remains in a consistent state; more precisely, it says that any transaction will take the database from one consistent state to another consistent state.
The consistency property does not say how the DBMS should handle an inconsistency other than ensure the database is clean at the end of the transaction. If, for some reason, a transaction is executed that violates the database’s consistency rules, the entire transaction could be rolled
back to the pre-transactional state – or it would be equally valid for the DBMS to take some patch-up action to get the database in a consistent state. Thus, if the database schema says that a particular field is for holding integer numbers, the DBMS could decide to reject attempts to put fractional
values there, or it could round the supplied values to the nearest whole number: both options maintain consistency.
The consistency rule applies only to integrity rules that are within its scope. Thus, if a DBMS allows fields of a record to act as references to another record, then consistency implies the DBMS must enforce referential integrity: by the time any transaction ends, each and every reference in the database must be valid. If a transaction consisted of an attempt to delete a record referenced by
another, each of the following mechanisms would maintain consistency:
- Abort the transaction, rolling back to the consistent, prior state;
- Delete all records that reference the deleted record (this is known as cascade delete); or,
- nullify the relevant fields in all records that point to the deleted record.
These are examples of Propagation constraints; some database systems allow the database designer to specify which option to choose when setting up the schema for a database.
Application developers are responsible for ensuring application level consistency, over and above that offered by the DBMS. Thus, if a user withdraws funds from an account and the new balance is lower than the account’s minimum balance threshold, as far as the DBMS is concerned, the
database is in a consistent state even though this rule (unknown to the DBMS) has been violated.
Isolation refers to the requirement that other operations cannot access or see data that has been modified during a transaction that has not yet completed. The question of isolation occurs in case of concurrent transaction, (i.e. transaction occurring at the same time) and with the same database. To preserve the database consistency, the need of isolation arises. Each transaction must remain unaware of other concurrently executing transactions, except that one transaction may be forced to wait for the completion of another transaction that has modified data that the waiting transaction requires. If the isolation system does not exist, then the database may remain in an inconsistent state. This may happen as in case of concurrent transaction, one transaction may leave some data-items in mid process and at the same time another concurrent transaction may try to access/alter the same data-item which may cause data inconsistency and may leave the database in an inconsistent
Durability is the ability of the DBMS to recover the committed transaction updates against any kind of system failure (hardware or software). Durability is the DBMS’s guarantee that once the user has been notified of a transaction’s success, the transaction will not be lost. The transaction’s data changes will survive system failure, and that all integrity constraints have been satisfied, so the DBMS won’t need to reverse the transaction. Many DBMSs implement durability by writing transactions into a transaction log that can be reprocessed to recreate the system state right before any later failure. A transaction is deemed committed only after it is entered in the log.
Durability does not imply a permanent state of the database. A subsequent transaction may modify data changed by a prior transaction without violating the durability principle.
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A new Rice University-led study of ancient predators remains reveals new information about how prehistoric humans found – or did not find – food.
For more than three decades, archaeologists thought that one potential source of meat — crucial for the development of the early human brain — was the flesh abandoned from sabertooth cat kills. Until very recently, researchers thought that prehistoric humans stripped flesh from abandoned animal carcasses to consume, but these ancient remains suggest that was not the case. The new research, conducted on fossil remains from 1.5 million years ago, reveals that sabertooth cats fully devoured the flesh of their prey and even consumed some bones.
These iconic ancient predators, named for their enormous upper canines, roamed the landscapes of Africa, Eurasia and the Americas from the Miocene to the late Pleistocene. Manuel Dominguez-Rodrigo, a visiting professor of anthropology at Rice and the study’s first author, was able to determine together with his colleagues the eating habits of these prehistoric cats based on their skeletons and those of their prey.
The discovery is significant, according to Dominguez-Rodrigo, because it indicates that early humans relied on various methods to find protein sources. It lends credence to the notion that early humans were already skilled hunters.
Dominguez-Rodrigo said the research helps further this area of study as it eliminates a source of this important type of food for ancient humans. However, he said, there are still a lot of unanswered questions about how prehistoric humans hunted and gathered food, and these topics will be the focus of future work.
Cover Photo: Examples of African warthog carcasses consumed by modern lions.
Source: Rice University |
Wheezing is a common respiratory symptom in children and can be caused by a variety of conditions. It is a high-pitched whistling sound that is usually heard when your child breathes out. In some cases, wheezing can be a sign of a more serious condition, so it is important to know when to seek medical attention.
If your child is experiencing wheezing, it is important to monitor their breathing and look for any signs of distress. If your child is having difficulty breathing, is using their chest muscles to breathe, or has blue lips or fingernails, seek medical attention immediately.
In addition, you should also see a doctor if your child has any of the following symptoms:
- Rapid breathing: If your child is breathing faster than usual, this could be a sign of a respiratory infection or asthma.
- Chest tightness: If your child is complaining of chest tightness or discomfort, this could be a sign of an asthma attack.
- Persistent cough: If your child has a persistent cough that is not going away, this could be a sign of a respiratory infection or asthma.
- Fever: If your child has a fever, this could be a sign of a respiratory infection that is causing the wheezing.
- Wheezing with exercise: If your child only experiences wheezing during or after exercise, this could be a sign of exercise-induced asthma.
If your child is experiencing any of these symptoms, it is important to make an appointment with their doctor. Your child’s doctor will be able to evaluate their symptoms and determine the best course of treatment.
In some cases, your child’s doctor may recommend a breathing treatment, such as an inhaler or nebulizer, to help alleviate their symptoms. They may also recommend allergy testing or other diagnostic tests to determine the underlying cause of the wheezing.
In conclusion, wheezing in children can be a cause for concern, especially if it is accompanied by other symptoms. If you notice your child wheezing, it is important to monitor their breathing and seek medical attention if necessary. Your child’s doctor will be able to evaluate their symptoms and provide the appropriate treatment to help them breathe easier. |
Diffusionism as an anthropological school of thought, was an attempt to understand the distribution of culture in terms of the origin of culture traits and their spread from one society to another.
Diffusion may be simply defined as the spread of a cultural item from its place of origin to other places . A more expanded definition depicts diffusion as the process by which discrete culture traits are transferred from one society to another, through migration, trade, war, or other contact .
Diffusionist research originated as a means of understanding the nature of the distribution of human cultural traits across the world. Diffusionism emerged as an “anti-evolutionist” school of thought, highly critical of the evolutionary school and its premise of “psychic unity of mankind”.
Versions of diffusionist thought –
- all cultures originated from one culture center (heliocentric diffusion);
- cultures originated from a limited number of culture centers (culture circles);
- each society is influenced by others but that the process of diffusion is both contingent and arbitrary .
Points of Reaction
- The cross-cultural encounters provided the impetus for the development of concepts concerning the processes involved in cultural progress .
- The concept of diffusion originated in its opposition to the concept of evolution, which proposed that all human beings possessed equal potential for inovation.
- It was in reaction to the concept of psychic unity of mankind.
- Human are basically uninventive.
- Important inventions were made only once at a particular place.
- They spread through diffusion to different places.
Characteristics of Diffusion
- Adoption of a cultural trait by a group depends on meaningfulness and usefulness the trait to the socio-economic life.
- The original form of the cultural trait need not he retained during the course of diffusion.
- Diffusion is more or less from a developed to underdeveloped culture.
- Diffusion may create culture change in the group that borrows.
- Barriers for diffusion include factor like transport, communication, ethnocentrism, geography etc.
Schools of Diffusion
Diffusionism is further classified into three schools- British, German and American.
I. British School of Diffusion
The British school is extreme diffusionist and anti-evolutiomst. It is also called Pan-Egyptian school or Heliocentric school because for these scholars, all the cultures originated from one culture centre- Egypt. Culture traits diffused or migrated to rest of the parts of the world from here.
The chief proponents are G. E. Smith W. J. Perry and W. H. R. Rivers.
II. German School of Diffusion
The German School is considered refined in its approach and methodology compared to their British counterparts. the development of culture occurs at several different places at several times. Thus, the culture traits originate independently, at several parts of the world and migrated to other places. Inventions and discoveries were continuous processes and they reach to other areas by migration.
The proponents in this school of anthropological thought were Frederick Ratzel, Frietz Graebner and Father William Schmidt. ‘
III. American School Of Diffusion
The diffusion of culture from one place to another is caused by the process of imitation. Borrowing the traits from one culture group is easier at times than to invent them within one’s own culture. The group which borrows a culture trait adopts it to suit the needs of its own culture. Thus, diffusion and modification are two principles that operate. The diffused traits are more similar in areas residing in a particular geography. The process of diffusion is more prevalent among cultural groups residing in close contact to each other. In order to explain diffusion, this group of scholars devised a methodology called Culture-Area approach. Under this approach, the world is divided into different cultural areas on the basis of geographical regions. Geographical aspects of culture are indispensable in studying culture areas. A study pursued through–this approach reveals that groups residing in close geographical area represent more uniformity than others. This is why the American school is also known as “Culture Area School”.
The American school of Diffusion is represented by Franz Boas, A. L. Kroeber and Clark Wissler.
Diffusion, as an anthropological school of thought, was a crucial part in the development of anthropological concepts, however, it has suffered with ethnocentric bias.This resulted in emergence of functional school of thought. |
Scientists have discovered traces of forest soil in Antarctica after carrying out analysis on sediment core that they collected back in 2017. This could have some major implications in our understanding of prehistoric geography.
Imagine a tropical forest standing where the immense glaciers currently reside in Antarctica. Sounds impossible, right? However, a team of scientists have actually managed to find forest soil from the Cretaceous period, about 90 million years ago, near the South Pole.
A 3-meter-long intact network of roots
Scientists from the University of Northumbria, with the help of German geologists from the Alfred Wegener Institute, made this discovery after carrying out analysis on sediment core that they collected in 2017 near Pine Island Glacier in western Antarctica.
This soil sample measured around three meters long and immediately stood out to scientists.
‘During the initial shipboard assessments, the unusual colouration of the sediment layer quickly caught our attention; it clearly differed from the layers above it,’ explained Johan Klages, author of the first study on this forest and whose findings were published in Nature magazine before later being picked up by other journals and media sources. Researchers also discovered a ‘network of in situ fossil foots’ that ran through almost the entire length of the sample.
An unexpected climate
Using the diverse pollen and spores that were present in this sediment core, scientists were able to create a climate model simulation which suggests that the continent was covered by a temperate rainforest around 90 million years ago.
The average temperature is said to have been around 12 degrees celsius, but which could have soared to almost 20 degrees during the summer months. It also rained just as much as it does in areas that currently get a lot of rain today, such as Wales.
This climate is very different to what we associate the Antarctica with today, although it does have to be said that the beginning of the Cretaceous period was one of the hottest periods over the last 140 million years. Further analysis of this sediment core will now be carried out to see if there are any other surprises hidden inside. |
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Sensory integration occurs automatically. It begins in utero as the fetal brain senses movement of the mother’s body.
The brain is primary a sensory processing machine, it senses things and gets meaning directly from sensations. Information enters our brain from all parts of our body at every moment.
The definition of “Fine Motor” is orderly progression that is deliberate and controlled movements requiring both muscle development and maturation of the central nervous system.
We need to be aware of the skills of the young child and plan activities accordingly.
We provide a Milestone List of fine motor control.
Two words we hear often in early childhood development are:
Nature – the child’s biological makeup
Nurture – the environmental influence
Cognitive development is the process of acquiring intelligence and increasingly advanced thought and problem solving ability from infancy to adulthood.
Pre Reading Skills-When to begin? What you can do to encourage it. How to help babies develop necessary skills.
Is the child at the expected level of development for reading? Perception. Phonology. Pre reading activities.
A 2 hour Certificate of Completion is issued for this workshop.
Separation Anxiety in Children
Separation anxiety is a part of the normal developmental process in children. It’s perfectly fine for a child under the age of 6 to be anxious and fearful about separating from their parent or caregiver, to whom they are emotionally attached. However, if the symptoms intensify beyond what’s healthy or if the condition persists beyond the age of 6 then it’s possible that the child may have separation anxiety disorder. |
Instructors who practice unconscious discrimination, or teacher bias, can hurt their students’ chances of learning effectively.
Have you ever caught yourself cringing at how many boys are in your class when you receive your class list? Maybe you’ve secretly cheered when a certain student shares he’ll be missing school for a vacation. Even teachers are human, so it’s normal to feel this way from time to time, but it’s essential to schedule time for personal reflection and evaluate whether you ever practice teacher bias.
A recent study by researchers at the Yale University Child Study Center discovered that preschool teachers have implicit biases based on the child’s gender and race. According to the Washington Post, 130 teachers were asked to watch video clips of children in classrooms and look for signs of “challenging behavior.” The study found that the teachers spent the most time watching black boys.
The first step to preventing teacher bias in your classroom is to recognize occasions where it may arise. Have you ever done one of these?
1. Assumed a student was “not getting it” because they were very introverted?
2. Punished a boy for something you would have let slide if it was a girl (or vice versa)?
3. Given a student a lower grade because of their behavior in the classroom?
4. Assumed a child was “bad” because another teacher said so?
5. Given up on a student who has a learning disability?
6. Believed boys are better at math and science than girls?
7. Only given examples that certain students can relate to?
These are all examples of teacher bias. Follow these steps to help overcome it.
1. Be Honest with Yourself
Every teacher tries their best to be objective with their students, but everyone has biases. Perhaps you had a family member who was very conscious of race or had a teacher who favored the most well-behaved students when it came to grades. Even if you condone those actions, be aware that these interactions may be part of your subconscious.
2. Create a Classroom that Promotes Diversity
Are there boys and girls of all races represented in the artwork in your classroom? Do the stories and lessons you teach reflect different cultures? Make sure your students’ learning space is a place where they feel comfortable, represented, and welcomed.
3. Encourage Students to Speak Out Against Bias and Injustice
Create an environment where everyone is responsible for respecting others and promoting respect. It sounds easier than it is, but every day is a new chance to keep trying.
It’s vital for students to know their educators believe in them in order to work hard. Through self-examination and mindfulness, teachers can get rid of biases in their classroom and make it easier for all of their students to succeed. |
There was an existence of a standardized indigenous cultural values in various Yoruba communities, which are handed over to generations, in form of a legacy. In the stereotypical values; are norms and rules that govern the existence of the Yoruba, to the effect that, a deviation from such norms may lead to a sanction from the community. Socialization through contact with the Western world exposed the Yoruba communities to another facet of life. Though, the facet of life was new and very strange, but, the people were influenced so greatly that, it served as a catalyst that spurred out an action. The action, in its totality, can be termed as a change, which was unavoidable at that instance, but, rather was, a way forward to survive the new grim existence. However, the changes identified in this paper, were grouped into periods of occurrence and were thereafter, discussed under a triumvirate, in order to bring about a proper analysis.
Culture, according to Oxford advance learners’ dictionary, is defined as the customs, beliefs, arts, ways of life and social organisation of a particular country or people. It can also be seen as human behaviour and the general ways of life which is being passed from one generation to the other inform of legacy. Socialization on the other hand, is an act of being social through contact. Socialization of Yoruba culture is defined within the context of this discuss, as the aspects of the indigenous Yoruba cultural values that have experienced some remarkable changes as a result of contact with the foreign or alien cultures of the Western world or Europe.
The changes identified are grouped into periods of events and are thereafter discussed under a triumvirate, viz: the Pre-colonial Era, Colonial, and the Post-colonial/the Era of new Assumptions. It is proved, based on historical facts, that some parts of Yoruba communities especially Lagos, had contact with the Western or European adventurists and traders inform of bilateral trade through exchange of goods inform of barter system. At this period, hides and skin, ivory, cocoa grain and other farm produce were exchanged with goods like clock, mirror, tobacco, gun powder and so on. The trade later led to slavery or slave trade; a situation where able-bodied men were carted away in chains and fetters through the Sea via the then Lagos colony and Badagry axis. Slavery came into being as a result of the fact that, man power were desperately needed as direct labour in Britain, America, and all over Europe to cultivate their expansive farmlands in order to meet the rising demands in industries that depend largely on farm products as raw materials.
The philosophy and psychology of most of these slaves changed to that of their masters. For instance, they (the slaves) believe in what the masters believe do what the masters do, dress like the masters, eat what they eat, imbibe their new cultures, learn their language, to mention but just a few. Though, the hegemony of the Europeans over the new Society of ‘slavery’ was somehow experimental. The slaves in turn were acting in accordance and conformity with the dictates and wishes of the masters. The culture of the masters, though very strange and extremely new became the vogue, everything Yoruba in nature became issues of the past. This therefore, forms the first phase of cultural change inflicted on indigenous Yoruba heritage through contact with the western world as a result of bilateral trade and slavery.
Religion and Education form the root of the second phase of the changes identified in the indigenous Yoruba culture. Religion can be regarded as the main aspect of Yoruba culture that has undergone a tremendous change as a result of socialization which was brought to being as a result of the unavoidable contacts with the west. It shall be recalled at this instance that, everything in Yoruba communities settles around the belief system of the people, nothing can be done or addressed independently of the religion and the belief of the people, for example, family name, festivals, betrothal and marriage, farming, attainment of puberty and adulthood, dressing, the secret societies, and so on are deeply rooted firmly around the belief system of the people through religion. Family names are used as means of identification in terms of religion, occupation, bravery, royalty, economy, among many others.
If a Yoruba man, names a child ‘Akinola’; the compound name ‘Akin’ is suggestive of the fact that, the family from which the child has come, is known for bravery and prowess, possibly their great grandfather was a powerful warrior. ‘Ayankunle’ is yet another name that shows from its compund name ‘Ayan’ that the family that bears the name is known for an ancient profession of drumming. ‘Ade’ and ‘Oye’ are names depict chieftaincy and royalty, ‘Ode’ is that of hunting, while ‘Ona’ is another compound name that suggests arts and creativity and so on. It is pathetic today that, Yoruba do no longer know what is in a name, as indigenous names are no longer in use. The few that are still functional are being changed on daily basis and replaced with baptismal Islam and xtian names. Similarly, many of such names are modified to synthesize into Western cultures so that, their pronunciations can sound foreign.
There was an established indigenous education system in various Yoruba communities before the contact with the western world. Western education system was later introduced by the Christian missionaries, in the mid nineteenth century, through Badagry axis, though the progress of western education in Yoruba communities was actually a feat performed by the Christian missionaries. In the school’s curriculum, teaching of arts as one of the subjects in missionary schools was deliberately left out initially, so as to discourage the new converts from ever using their forsaken religion (that is indigenous culture) as reference point. Another implication of this was that, anything cultural or Yoruba in nature was seeing as fetish.
It is factual that, a typical Yoruba cannot easily be separated from his arts, the arts serve as vital materials of his religion and belief system. Art is an important aspect of Yoruba culture; everything is incorporated and embedded in the cultural values. Today, it is very difficult for a man to identify or appreciate his own indigenous culture due to the fact that his mentality is lost to the west. He believes in what a white man believes, as a result of this, Yoruba language for example, is fast fading away as new or upcoming generations are seriously forbidden from speaking the language at home/school by their teachers and parents. A Yoruba man believes at the same time that, he is civilised and socialized as well if he speaks foreign language, imbibe foreign culture and behave foreign while he regard his own cultural values as forbidden, barbaric, inferior and highly unrefined.
The third aspect of the triumvirate which is the Post-colonial/the Era of new Assumptions, is actually the manifestation of the first two tenets of the triumvirates earlier discussed. At this time, all aspects of Yoruba culture had undergone remarkable changes both physical and psychological to the extent that, a Yoruba man that lives in his native community, yet, appears very far away from his own indigenous and stereotypical cultural values. The aspect of the physical change entails those aspects of Yoruba culture that are seen or felt in their daily usage. Good examples are dressing, language, greetings/exchange of pleasantries, moral standards, norms, and so on. A Yoruba child of this generation, born and bred in Yoruba community, due to the changes the culture had undergone in an holistic form, do not know how to greet his or her parents properly. He or she prefers to greet the parents while standing, or possibly give them a hand shake.
On the other hand, many consider prostrating or kneeling in greeting of elders in Yoruba culture as very conservative and barbaric. Speaking of Yoruba language is seen as a sigh of retrogression within the Yoruba communities, and that is why today, a Yoruba man cannot speak his own language conveniently for thirty minutes meanwhile, he speaks any chosen foreign language(s) for hours with ease and with great enthusiasm. The Yoruba indigenous way or process of betrothal has also been relegated to the background, because of its so called, unrefined nature. Many people that marry nowadays, in such communities, do not really know the essence and the importance of traditional marriage anymore, they opt for other types of marriage just to satisfy their quest for foreign values.
Conclusively, all the issues discussed in this paper, can be regarded as, only a fractional part of the whole of Yoruba traditional cultural values that, had undergone tremendous changes and bastardization due to socialization. All these make it so difficult for a Yoruba man, born and bred in his immediate community, to appreciate, appraise, identify, and by extension be proud of his own culture. |
The more scientists study the issue of food waste — and its worrying implications for both the environment and global food security — the clearer it becomes how much of a problem it is. Now, new research is giving us a few more reasons to clean our plates.
A study just out in the journal Environmental Science and Technology concludes that we’re already producing way more food than the world actually needs — but a lot of the excess is being wasted, instead of used to feed people who need it. That’s a big problem for global food security as well as for the climate, given the huge amounts of greenhouse gases that go into producing the extra food — and the study suggests that the problem will only get worse in the future.
Scientists are already aware of how bad food waste is for the environment. Just last week, we reported on the staggering carbon footprint associated with wasted food — the UN’s Food and Agriculture Organization reported that, in 2007, the emissions required to produce all the food that went to waste in the world amounted to at least 3.3 billion tons of carbon dioxide equivalent, more than most countries emitted. This estimate included all the emissions required to produce the uneaten food, including emissions from soil, livestock and the energy required to run a farm.
The new research, which was conducted by researchers from the Potsdam Institute for Climate Impact Research in Germany, suggests that in the future, food waste will grow — and the associated emissions will grow even faster.
“When we’re talking about the future food requirements — what can we do to meet the future food demand — we found that to investigate food waste is a quite crucial aspect,” said the paper’s lead author Prajal Pradhan, a postdoctoral researcher at Potsdam.
The researchers used U.N. data to calculate the difference between the amount of food available in each country and the amount its citizens require in order to be healthy. For each country, there was either more food available than was needed to supply the nation’s requirements — a food surplus — or not enough. The researchers considered food surplus to be equivalent to food waste, as it represents food that was not needed but produced anyway. Presumably, the majority of a food surplus is wasted, although the researchers noted in the paper that some of it is likely used for animal feed or is consumed by humans through overeating.
In order to estimate the greenhouse gases associated with food waste, the researchers turned to data from the FAO on the emissions associated with agriculture. It’s important to note that they did not include emissions associated with the energy required to operate farms, such as the electricity needed to run farm equipment — they only included emissions produced by soil and livestock, mostly nitrous oxide and methane. This means that the emissions reported by the new study are significantly underestimated.
The study found that the global food surplus increased overall between 1965 and 2010 from 310 extra kilocalories per person per day to 510 extra kilocalories, with the greatest surplus growth rates generally observed in developed nations. As of 2010, 20 percent more food was being produced worldwide than was actually needed to feed the world’s population, and overall the researchers estimated that the global surplus could be used to feed an extra 1.4 billion people. The UN estimates that about 800 million people worldwide suffer from undernourishment, meaning there’s currently enough wasted food in the world to solve the world’s hunger problem nearly twice over — it just isn’t reaching the people who need it.
The researchers also found that the agricultural emissions associated with all the extra food more than quadrupled between 1965 and 2010, from 130 million tons of carbon dioxide equivalent to 530 million tons. Again, these estimates don’t include the carbon emissions associated with energy use, so the reality is that the food waste’s carbon footprint was even higher — more like 3 billion tons, going by the FAO’s previous research.
Moreover, all of these problems are expected to grow worse in the coming decades. The researchers also conducted a series of projections based on different hypothetical scenarios involving the future world’s energy requirements and population growth and demographics.
They found that the food surplus will continue to grow in most countries, and the global surplus could grow as high as 850 kilocalories per person per day. Future waste-related emissions also increased in every scenario and grew at an even greater rate than the global food surplus — the result of predicted changes in the global diet.
In the future, meat is expected to become an even greater component of diets around the world, Pradhan explained — and meat is particularly energy intensive to produce. Altogether, food waste-related emissions could span anywhere from 1.9 to 2.5 billion tons of carbon dioxide equivalent per year — again, excluding emissions from the energy sector.
The study highlights several important problems in the current global food system. First, the finding that there’s more food than necessary in the world, while undernourishment still remains a global problem, implies that there are serious failings in the distribution of food worldwide.
“So much of poverty and famine aren’t about a lack of resources overall — they’re just distributional [problems],” said Emily Broad Leib, an assistant clinical professor of law and director of the Harvard Food Law and Policy Clinic. “It’s not surprising to see that, and both across countries and within countries this challenge of the food markets really being attainable for certain segments of the population and not for others.”
Addressing this problem, which likely stems in large part from income inequalities in countries where both surplus and hunger exist simultaneously, will be critical to addressing future food security.
And, of course, the study also reiterates the idea that food waste remains tied up with the issue of climate change. While research on the related carbon emissions, themselves, has turned up different values depending on the methods used to calculate them, it’s clear that wasted food is equivalent to the needless release of greenhouse gases, and the problem will only continue to grow unless concrete action is taken to stop it.
Such action will require steps to prevent food loss on the production side, which experts have suggested could be minimized with infrastructural improvements along the supply chain, as well as action to minimize food waste on the consumer end. The latter may prove to be less straightforward, but experts have proposed a number of steps, including consumer education campaigns and more accurate expiration date labeling on packaged food.
“One of the best outcomes would be getting consumers to make better decisions and have less waste at the household level and have supply chains adjust to that and redistribute that food earlier in the chain,” said Broad Leib.
Such action will likely also be important in helping the international community meet a broader set of sustainability goals outlined by the U.N., which include the goal of cutting food waste in half by 2030, Pradhan said.
“This study can provide a nice basis to show how much food is wasted now, and this information can be used also to achieve this sustainable development goal,” he said. |
Las maravillas de las Galápagos
Informational (nonfiction), 1,831 words, Level U (Grade 4), Lexile 1020L
Galapagos Wonder is an informational book about the remote Galapagos Islands. Readers will learn about the geology and formation of these unique islands, their unusual animals and plants, and conservation efforts aimed at preserving their natural ecology. Filled with interesting facts, this book is sure to encourage additional research in areas such as endangered wildlife and marine ecology.
More Book Options
Kurzweil 3000 Format
Use of Kurzweil 3000® formatted books requires the purchase of Kurzweil 3000 software at www.kurzweiledu.com.
Close Read Passages
carapace, current, diversity, ecology, feral, herbivorous, iguanas, naturalist, refuge, species, specimens, territorial
Use of vocabulary lessons requires a subscription to VocabularyA-Z.com.
Teach the Objectives
Use the reading strategy of summarizing to understand text
Main Idea and Details : Identify main idea and supporting details
Grammar and Mechanics
Verbs : Identify action verbs and verb phrases
Compound Words : Recognize and use open compound words
Think, Collaborate, Discuss
Promote higher-order thinking for small groups
or whole class |
The following information was taken from a Screenagers Tech Talk Tuesday Emailing.
Cyberbullying is a big concern for parents and kids alike. But defining it, and helping children and teens understand exactly what it means is challenging.
The definition of bullying from StopBullying.gov is:
“Bullying is unwanted, aggressive behavior among school-aged children that involves a real or perceived power imbalance. The behavior is repeated or has the potential to be repeated, over time. Both kids who are bullied and who bully others may have serious, lasting problems.
In order to be considered bullying, the behavior must be aggressive and include:
Children and teens either don’t recognize cyberbullying, or are often afraid, or unaware of how to stop it. Even if they see or hear about one incident that wouldn’t be considered, by definition, bullying. However, today’s technology allows for “one time” incidents to escalate quickly, and it can quickly turn into cyberbullying. The developing brain and lack of impulse control, etc. also can exasperate the problem.
Here are some things to discuss with your child/teen about cyberbullying and how we can put an end to this terrible trend:
This is an increasingly pervasive problem that we need to work together to help solve. That starts with conversations and helping children and teens alike understand the dire, long-term consequences that can be involved. If you believe your child is struggling with cyberbullying and needs help dealing with it, call TAG Counseling (678-297-0708) for a consultation.
Comments are closed. |
Eighteen-year-old Kevin Chan, a member of the Harvard College Class of 2004, used a supercomputer to discover a novel arrangement of atoms that had been missed by other scientists studying such clusters. Chan made the unexpected discovery in late June 2001 while working on a summer project at the San Diego Supercomputer Center (SDSC). Chan, a student majoring in mathematics, used a variation of a well-known mathematical technique to discover that 78 neutral atoms can theoretically settle into the shape of a particular “double icosahedron.” Icosahedrons are 20-sided objects. Chan used a variant of a so-called “basin-hopping” algorithm developed by Robert Leary, an applied mathematician at SDSC under whom Chan worked during the summer. The mathematician and his colleagues try to understand how 10 to more than 100 neutral atoms arrange themselves into clusters with the lowest-energy states possible. |
September 25, 2003
La Jolla, CA – Scientists are developing a new paradigm for how the brain functions. They propose that the brain is not a huge fixed network, as had been previously thought, but a dynamic, changing network that adapts continuously to meet the demands of communication and computational needs.
In the Sept. 26 issue of Science, Salk Institute professor Terrence Sejnowski and University of Cambridge professor Simon Laughlin argue that the human brain has evolved to operate as an enormously efficient “hybrid device,” capable of making far more sophisticated computations than the most powerful computers, and the long-distance communication systems in brains have been optimized by evolution for energy efficiency.
“In the past, we were only able to look at brain function by looking at single neurons or local networks of neurons. We were only able to see the trees, so to speak,” said Sejnowski. “With breakthroughs in recording techniques including brain imaging, which gives us a global picture of brain activity, and advances in computational neurobiology, we can now take a more global perspective. We’re looking at the entire forest, and we’re asking the question: How has the forest evolved?”
As the brain has evolved over millions of years, according to Sejnowski, it has become amazingly efficient and powerful. He says that nature has “optimized the structure and function of cortical networks with design principles similar to those used in electronic networks.” To illustrate the brain’s tremendous capacity, Sejnowski and Laughlin state that the potential bandwidth of all of the neurons in the human cortex is “comparable to the total world backbone capacity of the Internet in 2002.”
But they point out that simply comparing the brain to the digital computers of today does not adequately describe the way it functions and makes computations. The brain, according to Sejnowski, has more of the hallmarks of an “energy efficient hybrid device.”
“These hybrids offer the ability of analog devices to perform arithmetic functions such as division directly and economically, combined with the ability of digital devices to resist noise,” he writes in Science.
“This is an important era in our understanding of the brain,” according to Sejnowski. “We are moving toward uncovering some of the fundamental principles related to how neurons in the brain communicate. There is a tremendous amount of information distributed throughout the far-flung regions of the brain. Where does it come from? Where does it go? And how does the brain deal with all of this information?
“These are questions we’ve not been able to address on a comprehensive basis until now. I believe that over the next decade, we will begin to develop some answers.”
The Salk Institute for Biological Studies, located in La Jolla, Calif., is an independent, nonprofit organization dedicated to fundamental discoveries in the life sciences, the improvement of human health and conditions, and the training of future generations of researchers. The institute was founded in 1960 by Jonas Salk, M.D., with a gift of land from the City of San Diego and the financial support of the March of Dimes Birth Defects Foundation. |
By Ana Reisdorf, registered dietician and writer for Walgreens
Today's society has an image-driven culture that focuses on unrealistic standards of beauty for people of all genders, ages, and ethnicities. These standards not only have a negative impact on adults but are impacting children with alarming consequences.
Eating disorders among children have increased significantly in the past 20 years. While the greatest prevalence is among adolescents ages 13 to 18, children as young as 5 years old are dieting. More than ever, it’s important to teach children how to value healthy eating and stay active while also loving their bodies.
Here are some ways that you can teach your children to have a positive body image and develop healthy habits for life:
Be a role model for your child
Children tend to mimic the behaviors and actions of the adults around them. If children hear adults speak negatively about their own bodies, this may influence how they see themselves.
To combat this, work at being the role model your children need to see. State positive things about yourself and acknowledge that your imperfections are fine. Talk with your children about body diversity and why many media images are unrealistic. If you notice that your children are struggling with body image, be that understanding person they can speak to.
Change attitudes towards physical activity
Instead of focusing on exercise as a way to lose weight or maintain a certain body shape, have your children consider the other ways that being active can be a positive contribution to their lives. For example, physical activity helps your body reach its full potential, improves mood, acts as a social activity or artistic expression, and can be a lot of fun!
Try exposing your children to different ways of being active and engage their curiosities. They may be interested in sports like soccer or basketball, or find a passion for yoga, roller skating, or even Quidditch! If your children are concerned that they can't pursue an activity because of their size, show them how professional athletes come in different sizes and shapes.
Develop a healthy relationship with food
Moving away from the binary of "good" or "bad" foods is an important tool in improving your children's relationship with food. These labels create anxiety around food and may lead to consequences including food restriction and feeling like a bad person because they've eaten a "bad" food.
Promote healthy eating by emphasizing how the nutrients in foods help people become strong and healthy. Instead of focusing on calories, explain how the vitamins in an orange help their gums, or how nuts are good for their brain. And if your child wants to have a cookie or chips, there's no need to shame their food choices. Allow children to make some choices about the foods they eat and cultivate an environment where nutritious foods are available and appealing.
Celebrate your child's physical and non-physical attributes
Teaching your children to think positively about themselves can help develop a positive self-image that doesn't focus entirely on appearance. Practice stating what positive attributes they have and what they are capable of doing or becoming.
What are some things that your children like about their bodies? Do they like their smile, or how their body helps them climb up a tree? Don't forget your children's non-physical attributes — are they kind, funny, smart or talented at something? A regular practice of saying affirmations can reduce negative self-talk and build your children's confidence.
Teaching your children body positivity and healthy habits around food and physical activity can have a lasting impact on their self-esteem, self-perception and how they interact with an image-driven culture.
Ana Reisdorf, registered dietician and writer for Walgreens, shares her knowledge to help inform and encourage a healthy relationship with food. You can find an array of vitamins and supplements to help provide your body with the proper nutrients at Walgreens.com. |
Our Poetry: Introductory lesson plan introduces students to the world of poetry. This lesson expands students’ exposure to a variety of poetry forms with engaging activities while also providing experiential learning as student practice identifying and matching the various forms. During this lesson, students are asked to use their creativity and public speaking skills as they write and share their own poems. Students are also asked to match poems with their poetry type to demonstrate their understanding of the lesson.
At the end of the lesson, students will be able to read various forms of poetry and identify rhyme and structural elements of poems, identify various forms of poetry, and create various types of poetry.
Common Core State Standards: CCSS.ELA-LITERACY.RL.4.10, CCSS.ELA-LITERACY.RL.6.4, CCSS.ELA-LITERACY.RL.5.5 |
English Language Arts Grade 5
Language Standard 5
Demonstrate understanding of figurative language, word relationships, and nuances in word meanings.
Recognize and explain the meaning of common idioms, adages, and proverbs.
Can You Haiku?
Haiku show us the world in a water drop, providing a tiny lens through which to glimpse the miracle and mystery of life. Combining close observation with a moment of reflection, this simple yet highly sophisticated form of poetry can help sharpen students' response to language and enhance their powers of self-expression. In this lesson, students learn the rules and conventions of haiku, study examples by Japanese masters, and create haiku of their own.
How Big Are Martin's Big Words? Thinking Big about the Future
Martin's Big Words: The Life of Dr. Martin Luther King, Jr., a Caldecott Honor book, Coretta Scott King Honor book, and an Orbis Pictus Award winner, tells of King's childhood determination to use "big words" through biographical information and quotations. Using this book as well as other resources on Dr. King, students explore information on King's "big" words. They discuss both the literal and figurative meanings of the word "big" and how they apply to Dr. King's words. They read an excerpt from Dr. King's "I Have a Dream" speech and note the "big" words. Students then choose one of two options: (1) they write about their own "big" words and dreams in stapled or stitched books, or (2) they construct found poems using an excerpt from one of King's speeches.
Lonely as a Cloud: Using Poetry to Understand Similes
Students will gain knowledge by defining the term simile; apply this knowledge by identifying examples of similes in literature and poetry; practice analysis by examining the purpose and effect of similes in poetry; synthesize their knowledge by using a graphic organizer to create their own similes and then incorporating these similes into their own writing.
Paint By Idioms
Idioms add color to language. Help Salvabear Dali finish his paintings by identifying the correct expression.
Using a Touchstone Text
This Teaching Channel video shows an educator using a short engaging text to anchor a series of lessons on a tough concept. (5 minutes)
http://www.uen.org - in partnership with Utah State Board of Education
(USBE) and Utah System of Higher Education
(USHE). Send questions or comments to USBE Specialist -
and see the Language Arts - Elementary website. For
general questions about Utah's Core Standards contact the Director
- Jennifer Throndsen .
These materials have been produced by and for the teachers of the
State of Utah. Copies of these materials may be freely reproduced
for teacher and classroom use. When distributing these materials,
credit should be given to Utah State Board of Education. These
materials may not be published, in whole or part, or in any other
format, without the written permission of the Utah State Board of
Education, 250 East 500 South, PO Box 144200, Salt Lake City, Utah |
Spherical Triangles Exploration
All spherical triangles have angles adding up to more than 180°. We called the amount over 180° the defect of the triangle.
Larger triangles have larger defect. In fact, the defect of a triangle is proportional to its area:
Kaleidotile is a free computer program. Run Kaleidotile and play with it a bit. Try changing the control point, spinning the picture, and playing with the controls and menu options. Today, we're interested in the , , and symmetries, which give spheres.
- Explain the (flat) vs. (curved) styles.
Switch to the flat style, and use the symmetry group. Move the control point until you get an octahedron. Switch to curved style, and move the control point slightly to show the polygonal shapes.
- How many of these triangles are there (it may help to look at the picture in flat style).
- What fraction of the sphere does one of these triangles cover?
- What are the corner angles of these triangles?
- What is the defect of one of these triangles?
- What would <math>X</math> need to be to make formula (1) correct?
- Repeat question 2, but use the group and the tetrahedron.
- Repeat question 2, but use the group and the icosahedron.
- Return to the symmetry group and the tetrahedron. On the View menu, turn on the "Cut Along Mirror Lines" option. You should have a tessellation by small triangles with dark edges. Answer questions a-e for these triangles.
- Re-write formula (1) to give the area fraction in terms of the defect.
- Look at Concentric Rinds. What are the corner angles of the triangles in the outer rind? What is the defect of one of these triangles? Use the formula to calculate the fraction of the sphere covered by each triangle. How many triangles are there in the outer rind? |
Are you searching for a way to make math exciting to review? Or are you trying to explain to others why math games are not just play with no purpose? Look no further because there are numerous benefits for adding math games to your teaching toolkit.
Math games are an effective instructional strategy for reviewing math skills.
How so? Let’s get to it. Math games:
Reason #1 – Promote Math Talk
When kids play games with each other, it gives them something to talk about. This can happen during gameplay or after the game is complete. The key is providing students with a structure that fosters productive discussions and academic vocabulary. This can include sentence frames, Math Talk cards or guided questions that are specific to the game.
Reason #2 – Create Time for Observation
While your kids are engrossed with playing math games, you are free to observe and assess in an informal setting. You can watch the actions they take and the decisions they make. Record what you notice by taking notes. Your kids won’t notice what you are doing and the pressure of “testing” will not be present.
Reason #3 – Provide an Alternative Way to Review
Doing the same thing over and over again can get boring, but games offer different outcomes. Unlike drills, games allow opportunities for repeated practice in a non-threatening manner. It’s more informal because it’s perceived as a fun activity plus it gives students another chance to review important math skills.
Looking for engaging math games? Click on your grade level below:
Reason #4 – Encourage Cooperative Learning
Depending on the type of game, students can work in groups or pairs. Working with peers helps improve interpersonal skills (communicating, being a team player, problem-solving, etc.) The time spent with face to face interactions provides the practice needed to develop these skills.
Now let’s keep it real. As educators, I am sure that you would agree that some of our kids don’t always come to the table with these skills. That is why it is very important that we repeatedly model for students how these skills look. Playing games is a great way to practice them.
Reason #5 – Support Different Learning Styles
Let’s talk about differentiation. Our kids learn in different ways, just like us! So, why not use math activities that reach multiple students. This is where games come in. Games are great for:
- Visual Learners – when there are models and picture representations
- Kinesthetic Learners – when games include hands-on experiences and movement
- Auditory Learners – when kids openly communicate and talk to each other
- Read/Write Learners – when students use a recording sheet to find their solution
Reason #6 -Increase Student Engagement and Motivation
Plain and simple, kids (and adults!) enjoy playing games. So let’s use this love of play to foster a positive attitude about math. I have seen student faces light up when introducing new math games for center work. When given a choice, will students freely choose to participate in whole group gameplay or complete a worksheet? I think you know the answer.
Reason #7 – Develop Strategic Thinking
You know how you feel when you are searching for that perfect Jenga piece to pull from the tower without making it all fall down (“Should I pull from the top or the bottom?” “This one looks a little loose. Should I tap it?”) Your kids are making similar decisions when they play math games. They may not know it, but they are thinking strategy. (“What is the quickest way to solve this problem so that I can advance?”)
Reason #8 – Build Home-School Connections
Don’t have a clue what to do for Back to School or Family Nights? Play games! Instead of a PowerPoint, show parents what types of activities are happening in your classroom. This way they can get a real picture of what their kids will be doing and have a good time doing it!
Another way to bridge the home to school gap is to provide choice with homework. Don’t be afraid to mix it up! Since the purpose of homework is to practice previously taught skills, send home a familiar review game. Just make sure that they are simple games that can also be played independently.
Looking for engaging math games, that meet the criteria above? Click on your grade level below:
Math games have a rightful place in your classroom. They are a proven way to get your kids excited about math review. Add them as a normal part of your instruction and start experiencing the benefits immediately. And if anyone says “They are just playing”, share some of the benefits you learned about here. |
What’s the Number? A Place Value Guessing Game
This is a fantastic game to help children with place value. Here’s how….
templates (click here for more details or to purchase templates)
contact paper or lamination
dry erase marker
Print the templates. Cut along the dotted line on the millions page and discard the excess paper.
Glue or tape the three templates together so they look like this. Note: these templates are printed in pieces on purpose. When working with younger students/children you will want to begin with only the hundreds, tens and ones portion. As students become more proficient and with older students you can add the other two pages on to add more of a challenge.
Laminate or cover with contact paper for multiple uses.
How to Play
Decide how many digits you are going to work with and cover up the extra space so they are not distracting.
Hang the game board on the classroom board or lay it on a table in front of a small group.
Choose a number and write it on a slip of paper (or just remember it).
Have the first player choose a number and a place. For example, she might say, “Is there a one in the hundreds place?”
The teacher/adult then answers either “Yes” and writes the number in the hundreds place or
says “No” and crosses off that number in the small box below the hundreds place.
Note: Having this box and keeping track of incorrect guesses, models organization skills and keeps students from guessing what others have already guessed.
The game continues in this manner until all the digits have been guessed and the final number is complete and shared.
* * * * * * * * *
Templates available for purchase. Click the following link for details or to purchase:
* * * * * * * * * *
© Boy Mama Teacher Mama 2013
All Rights Reserved |
Research methods that emphasize detailed, personal descriptions of phenomena.
Research psychologists can collect two kinds of information: quantitative data and qualitative data. Quantitative data are often represented numerically in the form of means, percentages, or frequency counts. Such data are often referred to as "measurement" data, referring to the fact that we often like to measure the amount or extent of some behavior, trait, or disposition. For example, shyness, test anxiety, and depression can all be appraised by means of paper-and-pencil tests which yield numerical scores representing the extent of shyness, anxiety, etc. that resides in the individual taking the test. A psychologist interested in the relationship between test anxiety and grade point average would collect the appropriate quantitative information on each of these two variables and conduct statistical tests that would reveal the strength (or absence) of the relationship.
The term "qualitative research methods" refers to a variety of ways of collecting information that is less amenable to quantification and statistical manipulation. Qualitative methods differ from quantitative methods largely because their ultimate purpose is different. The goal of qualitative research is to arrive at some general, overall appreciation of a phenomenon—highlighting interesting aspects and perhaps generating specific hypotheses. In contrast, quantitative research is typically designed to test relatively specific predictions. Qualitative research thus provides an initial description of a phenomenon, whereas quantitative research aims to investigate its various details. Some examples of qualitative methods include focus groups, surveys, naturalistic observations, interviews, content analyses of archival material, and case studies. What these approaches share is an emphasis on revealing some general pattern by observing a few particular cases.
Focus groups are commonly used by marketing or advertising agencies to derive information about people's reactions to a particular product or event. A small number of people, often fewer than 10, are asked their opinions. A focus group engaged by the marketing department of a breakfast cereal company, for example, might be asked how appealing the cereal looks, whether the box would make them consider buying it, and how agreeable the cereal's texture and taste were. A facilitator would encourage the participants to share their opinions and reactions in the context of a group discussion. The session would be taped and transcribed. Researchers would then use the information to make their product more appealing. Naturalistic observations involve studying individuals in their natural environments. One common variant consists of participant observation research in which the researcher, in order to understand it, becomes part of a particular group. George Kirkham was a criminologist who took a year off from his university position to work as a police patrolman. He then wrote about the changes in his attitudes and values that occurred when he worked in high-crime neighborhood.
There are several drawbacks to qualitative methods of inquiry. Firstly, the results are always subject to personal biases. A person who is interviewed, for example, is stating their version of the truth. Personal perspectives invariably affect what the individual believes and understands. Similarly, the results reported by the researcher conducting a naturalistic observation will be tainted by that researcher's individual interpretation of the events. Further, while case studies are rich sources of information about individuals, it is risky to assume that the information can be generalized to the rest of the population. Moreover, analyzing the data from qualitative research can be difficult, since open-ended questions and naturalistic observation leave room for so much variability between individuals that comparisons are difficult. Finally, although it may be tempting for researchers to infer cause and effect relationships from the results of naturalistic observations, interviews, archival data and case studies, this would be irresponsible. Qualitative methods rarely attempt to control any of the factors that affect situations, so although one factor may appear to have caused an event, its influence cannot be confirmed without conducting more precise investigations. There is thus a tradeoff between flexibility and precision.
The advantages of doing qualitative research are numerous. One of the most important of these is that the flexibility of qualitative data collection methods can provide researchers access to individuals who would be unable or unwilling to respond in more structured formats. For this reason, much research on children is qualitative. Naturalistic observations of children are sometimes undertaken to assess social dynamics. For example, covert videotaping of elementary school playgrounds has revealed that bullying and aggression are far more common than most teachers and parents realize, and that bullying is not uncommon among girls. Similarly, comparative psychologists learn a lot about the social, behavioral, and cognitive abilities of animals by studying them in their natural habitats. A further advantage of this type of research is that the validity of the results is not jeopardized by the laboratory environment. An animal or child may not act the way they usually would in their natural surroundings if they are studied in a laboratory.
Another important application of qualitative research is in the study of new areas of interest, or topics about which not very much is known. Qualitative research usually yields a lot of information. In contrast with quantitative research, the information gathered by qualitative researchers is usually broadly focused. This means that qualitative methods can yield information about the major factors at play, highlighting areas that might warrant more in-depth quantitative study. Although many researchers believe quantitative methods to be superior to qualitative methods, the two are probably best seen as complementary. Qualitative research can suggest what should be measured and in what way, while controlled quantitative studies may be the most accurate way of doing the actual measuring.
Timothy E. Moore
Murray, J. "Qualitative methods." International Review of Psychiatry, vol 10, no. 4 (1998): 312-316.
Marecek, J. "Qualitative methods and social psychology." Journal of Social Issues vol 53, no. 4 (1997): 631-644. |
Tremor is defined as an unintentional, rhythmic, oscillatory muscle contraction causing shaking movements of one or more parts of the body. It can affect the hands, head, face, jaw, lips, torso, and legs. Sometimes the voice may be affected as well.
Hand tremor is the most common form.
Tremor is a normal physiologic phenomenon. Most of us see our hands shaking slightly when we hold them out in front of us. Several factors, such as stress, anxiety, lack of sleep, smoking, and caffeine may exaggerate this tremor.
Although tremor is usually not a sign of a severe or life-threatening medical disorder, it can be both embarrassing and disabling to some people and make it harder to perform work and daily life tasks.
Tremor may occur at any age but is most common in middle-aged and older adults. It tends to affect men and women equally.
Tremors are classified as rest or action tremors.
Rest tremor occurs when the affected body part is completely supported against gravity. It may be an arm or a hand that is resting in the patient’s lap. Action tremors, on the other hand, are produced by voluntary muscle contraction. They may occur when writing or lifting a cup of coffee.
Postural tremor is a sub-type of action tremors and occurs when the person maintains a position against gravity such as holding the arms outstretched (1). Postural and action tremors, including exaggerated physiologic tremor and essential tremor, comprise the largest groups.
1. Exaggerated Physiologic Tremor
All normal persons exhibit physiologic tremor. However, it may often be invisible to the naked eye.
Physiological tremor is most evident in the outstretched hands but can be detected in the legs, head, trunk, jaw, and lips.
Enhanced physiologic tremor may be caused by medical conditions such as thyrotoxicosis (overactive thyroid gland), hypoglycemia (low blood sugar), the use of certain drugs, or withdrawal from alcohol, opioids or benzodiazepines. It is usually reversible once the cause is corrected (1).
Beta blockers, also known as beta-adrenergic blocking agents, are medications that may be used to reduce the amplitude of trembling during fine manual work (2). Beta blockers work by blocking the effects of the hormone epinephrine, also known as adrenaline. They are often used to treat high blood pressure (3), heart palpitations (4) and tremor due to an overactive thyroid gland.
2. Essential Tremor
Essential tremor is the most common neurologic disorder that causes postural or action tremor. It is also the most common movement disorder worldwide.
The prevalence increases markedly with age and ranges from 4.1 to 39.2 cases per 1,000 persons, to as high as 50.5 per 1,000 in persons older than 60 years (5). These figures may underestimate the actual prevalence, however, because up to 50 percent of persons with mild essential tremor are unaware of it (6).
More than half of patients with essential tremor have a family history of the disorder (7).
Essential tremor usually develops insidiously and progresses slowly. It often occurs first in the hands and forearms and may be more prominent on one side of the body and increases with goal-directed activity (e.g., drinking from a glass of water or writing).
Essential tremor may also affect the head, voice, jaw, lips, and face. It can include a”yes-yes” or “no-no” motion of the head.
The shaking usually increases with stress, fatigue, and certain medications such as central nervous stimulants. It may also increase with specific voluntary activities such as holding a spoon or a cup.
Interestingly, there is often a degree of voluntary control. Hence, the trembling may be suppressed by performing skilled manual tasks (8).
Although sometimes disabling, essential tremor is in itself a benign disorder and not life-threatening.
Rest, beta blockers, primidone (Mysoline), and alcohol ingestion decrease the trembling.
Primidone and propranolol are the cornerstones of maintenance medical therapy for essential tremor. These medications provide clinical benefit in approximately 50-70% of patients (9).
3. Parkinson’s Disease
Although Parkinson’s disease is probably 20 times less common than essential tremor, about one million Americans suffer from the disease (10).
Tremor is a common symptom of Parkinson’s disease and other Parkinsonian syndromes. However, it is not experienced by all patients with Parkinson’s disease.
The tremor includes shaking in one or both hands at rest. It may also affect the chin, lips, face, and legs. The shaking may initially appear in only one limb or on just one side of the body. It is often made worse by stress, strong emotions, and after exercise.
Sometimes, the trembling only affects the hand or fingers. This type of shaking is often seen in people with Parkinson’s disease and is called a “pill-rolling” tremor because the circular finger and hand movements resemble rolling of small objects or pills in the hand.
Although the trembling of Parkinson’s disease is usually defined as a resting tremor, more than 25 percent of people with Parkinson’s disease also have an associated action tremor (11).
The trembling of Parkinson’s disease differs from essential tremor in three fundamental ways (12):
- Essential tremor is more likely to occur during voluntary activity of the hands whereas the trembling of Parkinson’s disease is more prominent at rest.
- Parkinson’s disease is usually associated with stooped posture, slow movement, and shuffling gait.
- Essential tremor mainly involves the hands, head, and voice. Parkinson’s disease tremors usually start in the hands and arms but also affect the legs, chin, and other parts of your body.
Although Parkinson’s disease can’t be cured, medications may markedly improve symptoms.
4. Intention Tremor (Cerebellar Tremor)
Intention tremor, also known as cerebellar tremor, presents as a unilateral or bilateral shaking, most often caused by stroke, brainstem tumor, or multiple sclerosis (1).
The neurological examination will reveal that finger-to-nose, finger-to-finger, and heel-to-shin testing result in increased shaking as the extremity approaches the target. Other signs include abnormalities of gait, speech, and ocular movements and inability to perform rapid alternating hand movements.
That the shaking typically increases in severity as the hand moves closer to its target, is in contrast to postural and action tremor (like essential tremor), which either remains constant throughout the range of motion or abruptly increase at terminal fixation (13).
Ataxia, a lack of voluntary coordination of muscle movements that includes gait abnormality, is typically associated with cerebellar tremor.
5. Wilson Disease
Wilson disease is a rare autosomal recessive inherited disorder of copper metabolism that is characterized by excessive deposition of copper in the liver, brain, and other tissues (14). Wilson disease is often fatal if not recognized and treated when symptomatic.
Liver dysfunction is the presenting feature in more than half of patients.
The most common presenting neurologic feature is an asymmetric tremor, which is variable in character.
Wilson disease may also be associated with difficulty speaking, excessive salivation, ataxia, clumsiness with the hands, and personality changes.
6. Rubral Tremor
Rubral tremor, also known as Holmes tremor, is a rare symptomatic movement disorder, characterized by a combination of resting, postural, and action tremors.
It is usually caused by lesions involving the brainstem, thalamus, and cerebellum.
The disorder is often difficult to treat. Many medications have been used with varying degrees of success (15).
7. Primary Writing Tremor
Shaking that occurs exclusively while writing, and not during other voluntary motor activities, is referred to as primary writing tremor. Hence, it is a task-specific tremor that predominantly occurs and interferes with handwriting (16).
The cause and pathophysiology of this disorder are still unknown. It has been classified as a focal form of essential tremor and as a tremulous form of writer’s cramp (17).
Botulinum toxin injections and deep brain stimulation may be treatment choices for primary writing tremor (18).
8. Orthostatic Tremor
Orthostatic tremor is a rare disorder, characterized by a rapid trembling limited to the legs and trunk (19). It occurs exclusively while standing.
The disorder is often associated with extreme straining of both legs, fatigue, unsteadiness and a fear of falling. Standing upright for only a short period may be difficult.
The shaking may disappear partially or completely when an affected person is walking or sitting.
There is controversy within the medical literature regarding whether orthostatic tremor is a variant of essential tremor, an exaggerated physiological response to standing still or a distinct clinical entity (20).
The disorder may respond to treatment with clonazepam or gabapentin (Neurontin) (21).
9. Functional Tremor (Psychogenic Tremor)
Functional tremor, also known as psychogenic tremor, is a variable tremor that may decrease or disappear when not under direct observation.
Functional tremor is classified as a functional movement disorder, a term that is applied to disorders that manifest with physical symptoms, specifically abnormal movements (gait disorders, tremor, dystonia, etc.) but which cannot be attributed to any of known underlying organic disorders and which instead is presumed to be due to “psychological factors” (22).
Any body part may be involved, but, remarkably, the fingers are often spared with much of the trembling of the arm occurring at the wrist (13).
A characteristic that suggests functional rather than organic tremors is abrupt onset with immediate maximal severity, often precipitated by trivial emotional or physical trauma (23).
Patients with functional tremor often have more than one movement disorder, which can be a helpful clue to the diagnosis.
10. Drug-Induced Tremors
Several medications can cause or exacerbate tremor (1).
Examples are amiodarone, atorvastatin, beta-adrenergic agonists (albuterol, terbutaline, salbutamol) carbamazepine, corticosteroids, fluoxetine, haloperidol, lithium, methylphenidate, synthetic thyroid hormones, tricyclic antidepressants, valproic acid, and verapamil.
The shaking may affect the hands, arms, head, or eyelids. It rarely affects the lower body and may not always affect both sides of the body equally (24).
Drug-induced tremor will usually disappear when the medication causing the symptoms is stopped.
If the benefit of the medicine is greater than the problems caused by the tremor, lowering the dose may sometimes be helpful. |
Because the major function of the kidneys is to filter the blood, a rich blood supply is delivered by the large renal arteries. The renal artery for each kidney enters the renal hilus and successively branches into segmental arteries and then into interlobar arteries, which pass between the renal pyramids toward the renal cortex. The interlobar arteries then branch into the arcuate arteries, which curve as they pass along the junction of the renal medulla and cortex. Branches of the arcuate arteries, called interlobular arteries, penetrate the renal cortex, where they again branch into afferent arterioles, which enter the filtering mechanisms, or glomeruli, of the nephrons.
Figure 1. (a) The urinary system, (b) the kidney, (c) cortical nephron, and (d) juxtamedullary nephron of the kidneys.
Blood leaving the nephrons exits the kidney through veins that trace the same path, in reverse, as the arteries that delivered the blood. Interlobular, arcuate, interlobar, and segmental veins successively merge and exit as a single renal vein.
Autonomic nerves from the renal plexus follow the renal artery into the kidney through the renal hilus. The nerve fibers follow the branching pattern of the renal artery and serve as vasomotor fibers that regulate blood volume. Sympathetic fibers constrict arterioles (decreasing urine output), while less numerous parasympathetic fibers dilate arterioles (increasing urine output).
The kidney consists of over a million individual filtering units called nephrons. Each nephron consists of a filtering body, the renal corpuscle, and a urine‐collecting and concentrating tube, the renal tubule. The renal corpuscle is an assemblage of two structures, the glomerular capillaries and the glomerular capsule, shown in Figure 1.
- The glomerulus is a dense ball of capillaries (glomerular capillaries) that branches from the afferent arteriole that enters the nephron. Because blood in the glomerular capillaries is under high pressure, substances in the blood that are small enough to pass through the pores (fenestrae, or endothelial fenestrations) in the capillary walls are forced out and into the encircling glomerular capsule. The glomerular capillaries merge, and the remaining blood exits the glomerular capsule through the efferent arteriole.
- The glomerular capsule is a cup‐shaped body that encircles the glomerular capillaries and collects the material (filtrate) that is forced out of the glomerular capillaries. The filtrate collects in the interior of the glomerular capsule, the capsular space, which is an area bounded by an inner visceral layer (that faces the glomerular capillaries) and an outer parietal layer. The visceral layer consists of modified simple squamous epithelial cells called podocytes, which project branches that bear fine processes called pedicels. The pedicels' adjacent podocytes mesh to form a dense network that envelops the glomerular capillaries. Spaces between the pedicels, called filtration slits, are openings into the capsular space that allow filtrate to enter the glomerular capsule.
- The renal tubule consists of three sections:
- The first section, the proximal convoluted tubule (PCT), exits the glomerular capsule as a winding tube in the renal cortex. The wall of the PCT consists of cuboidal cells containing numerous mitochondria and bearing a brush border of dense microvilli that face the lumen (interior cavity). The high‐energy yield and large surface area of these cells support their functions of reabsorption and secretion.
- The middle of the tubule, the nephron loop, is shaped like a hairpin and consists of a descending limb that drops into the renal medulla and an ascending limb that rises back into the renal cortex. As the loop descends, the tubule suddenly narrows, forming the thin segment of the loop. The loop subsequently widens in the ascending limb, forming the thick segment of the loop. Cells of the nephron loop vary from simple squamous epithelium (descending limb and thin segment of ascending limb) to cuboidal and low columnar epithelium (thick segment of ascending limb) and almost entirely lack microvilli.
- The final section, the distal convoluted tubule (DCT), coils within the renal cortex and empties into the collecting duct. Cells here are cuboidal with few microvilli.
Renal tubules of neighboring nephrons empty urine into a single collecting duct. Here and in the final portions of the DCT, there are cells that respond to the hormones aldosterone and antidiuretic hormone (ADH), and there are cells that secrete H + in an effort to maintain proper pH.
Various collecting ducts within the medullary pyramids merge to form papillary ducts, which drain eventually into the renal pelvis through the medullary papillae. Urine collects in the renal pelvis and drains out of the kidney through the ureter.
The efferent arteriole carries blood away from the glomerular capillaries to form peritubular capillaries. These capillaries weave around the portions of the renal tubule that lie in the renal cortex. In portions of the nephron loop that descend deep into the renal medulla, the capillaries form loops, called vasa recta, that cross between the ascending and descending limbs. The peritubular capillaries collect water and nutrients from the filtrate in the tubule. They also release substances that are secreted into the tubule to combine with the filtrate in the formation of urine. The capillaries ultimately merge into an interlobular vein, which transports blood away from the nephron region.
There are two kinds of nephrons:
- Cortical nephrons, representing 85 percent of the nephrons in the kidney, have nephron loops that descend only slightly into the renal medulla (refer to Figure 1).
- Juxtamedullary nephrons have long nephron loops that descend deep into the renal medulla. Only juxtamedullary nephrons have vasa recta that traverse their nephron loops (refer to Figure 1).
The juxtaglomerular apparatus (JGA) is an area of the nephron where the afferent arteriole and the initial portion of the distal convoluted tubule are in close contact. Here, specialized smooth muscle cells of the afferent arteriole, called granular juxtaglomerular (JG) cells, act as mechanoreceptors that monitor blood pressure in the afferent arteriole. In the adjacent distal convoluted tubule, specialized cells, called macula densa, act as chemoreceptors that monitor the concentration of Na + and Cl – in the urine inside the tubule. Together, these cells help regulate blood pressure and the production of urine in the nephron.
The operation of the human nephron consists of three processes:
These three processes, which determine the quantity and quality of the urine, are discussed in the following sections.
When blood enters the glomerular capillaries, water and solutes are forced into the glomerular capsule. Passage of cells and certain molecules are restricted as follows:
- The fenestrae (pores) of the capillary endothelium are large, permitting all components of blood plasma to pass except blood cells.
- A basement membrane (consisting of extracellular material) that lies between the capillary endothelium and the visceral layer of the glomerular capsule blocks the entrance of large proteins into the glomerular capsule.
- The filtration slits between the pedicels of the podocytes prevent the passage of medium‐sized proteins into the glomerular capsule.
The net filtration pressure (NFP) determines the quantity of filtrate that is forced into the glomerular capsule. The NFP, estimated at about 10 mm Hg, is the sum of pressures that promote filtration less the sum of those that oppose filtration. The following contribute to the NFP:
- The glomerular hydrostatic pressure (blood pressure in the glomerulus) promotes filtration.
- The glomerular osmotic pressure inhibits filtration. This pressure is created as a result of the movement of water and solutes out of the glomerular capillaries, while proteins and blood cells remain. This increases the concentration of solutes (thus decreasing the concentration of water) in the glomerular capillaries and therefore promotes the return of water to the glomerular capillaries by osmosis.
- The capsular hydrostatic pressure inhibits filtration. This pressure develops as water collects in the glomerular capsule. The more water in the capsule, the greater the pressure.
The glomerular filtration rate (GFR) is the rate at which filtrate collectively accumulates in the glomerulus of each nephron. The GFR, about 125 mL/min (180 liters/day), is regulated by the following:
- Renal autoregulation is the ability of the kidney to maintain a constant GFR even when the body's blood pressure fluctuates. Autoregulation is accomplished by cells in the juxtaglomerular apparatus that decrease or increase secretion of a vasoconstrictor substance that dilates or constricts, respectively, the afferent arteriole.
- Neural regulation of GFR occurs when vasoconstrictor fibers of the sympathetic nervous system constrict afferent arterioles. Such stimulation may occur during exercise, stress, or other fight‐or‐flight conditions and results in a decrease in urine production.
- Hormonal control of GFR is accomplished by the renin/angiotensinogen mechanism. When cells of the juxtaglomerular apparatus detect a decrease in blood pressure in the afferent arteriole or a decrease in solute (Na + and Cl –) concentrations in the distal tubule, they secrete the enzyme renin. Renin converts angiotensinogen (a plasma protein produced by the liver) to angiotensin I. Angiotensin I in turn is converted to angiotensin II by the angiotensin‐converting enzyme (ACE), an enzyme produced principally by capillary endothelium in the lungs. Angiotensin II circulates in the blood and increases GFR by doing the following:
- Constricting blood vessels throughout the body, causing the blood pressure to rise
- Stimulating the adrenal cortex to secrete aldosterone, a hormone that increases blood pressure by decreasing water output by the kidneys
In healthy kidneys, nearly all of the desirable organic substances (proteins, amino acids, glucose) are reabsorbed by the cells that line the renal tube. These substances then move into the peritubular capillaries that surround the tubule. Most of the water (usually more than 99 percent of it) and many ions are reabsorbed as well, but the amounts are regulated so that blood volume, pressure, and ion concentration are maintained within required levels for homeostasis.
Reabsorbed substances move from the lumen of the renal tubule to the lumen of a peritubular capillary. Three membranes are traversed:
- The luminal membrane, or the side of the tubule cells facing the tubule lumen
- The basolateral membrane, or the side of the tubule cells facing the interstitial fluids
- The endothelium of the capillaries
Tight junctions between tubule cells prevent substances from leaking out between the cells. Movement of substances out of the tubule, then, must occur through the cells, either by active transport (requiring ATP) or by passive transport processes. Once outside of the tubule and in the interstitial fluids, substances move into the peritubular capillaries or vasa recta by passive processes.
The reabsorption of most substances from the tubule to the interstitial fluids requires a membrane‐bound transport protein that carries these substances across the tubule cell membrane by active transport. When all of the available transport proteins are being used, the rate of reabsorption reaches a transport maximum (Tm), and substances that cannot be transported are lost in the urine.
The following mechanisms direct tubular reabsorption in the indicated regions:
- Active transport of Na + (in the PCT, DCT, and collecting duct). Because Na + concentration is low inside tubular cells, Na + enters the tubular cells (across the luminal membrane) by passive diffusion. At the other side of the tubule cells, the basolateral membrane bears proteins that function as sodium‐potassium (Na +‐K +) pumps. These pumps use ATP to simultaneously export Na + while importing K +. Thus, Na + in the tubule cells is transported out of the cells and into the interstitial fluid by active transport. The Na + in the interstitial fluid then enters the capillaries by passive diffusion. (The K + that is transported into the cell leaks back passively into the interstitial fluid.)
- Symporter transport (secondary active transport) of nutrients and ions (in the PCT and nephron loop). Various nutrients, such as glucose and amino acids, and certain ions (K + and Cl –) in the thick ascending limb of the nephron loop are transported into the tubule cells by the action of Na + symporters. A Na + symporter is a transport protein that carries both Na + and another molecule, such as glucose, across a membrane in the same direction. Movement of glucose and other nutrients from the tubular lumen into the tubule cells occurs in this fashion. The process requires a low concentration of Na + inside the cells, a condition maintained by the Na +‐K + pump operating on the basolateral membranes of the tubule cells. The movement of nutrients into cells by this mechanism is referred to as secondary active transport, because the ATP‐requiring mechanism is the Na +‐K + pump and not the symporter itself. Once inside the tubular cells, nutrients move into the interstitial fluid and into the capillaries by passive processes.
- Passive transport of H 2 O by osmosis (in the PCT and DCT). The buildup of Na + in the peritubular capillaries creates a concentration gradient across which water passively moves, from tubule to capillaries, by osmosis. Thus, the reabsorption of Na + by active transport generates the subsequent reabsorption of H 2O by passive transport, a process called obligatory H 2O reabsorption.
- Passive transport of various solutes by diffusion (in the PCT and DCT, and collecting duct). As H 2O moves from the tubule to the capillaries, various solutes such as K +, Cl –, HCO 3 –, and urea become more concentrated in the tubule. As a result, these solutes follow the water, moving by diffusion out of the tubule and into capillaries where their concentrations are lower, a process called solvent drag. Also, the accumulation of the positively charged Na + in the capillaries creates an electrical gradient that attracts (by diffusion) negatively charged ions (Cl –, HCO 3 –).
- H 2 O and solute transport regulated by hormones (in the DCT and collecting duct). The permeability of the DCT and collecting duct and the resultant reabsorption of H 2O and Na + are controlled by two hormones:
- Aldosterone increases the reabsorption of Na + and H 2O by stimulating an increase in the number of Na +‐K + pump proteins in the principal cells that line the DCT and collecting duct.
- Antidiuretic hormone (ADH) increases H 2O reabsorption by stimulating an increase in the number of H 2O‐channel proteins in the principal cells of the collecting duct.
In contrast to tubular reabsorption, which returns substances to the blood, tubular secretion removes substances from the blood and secretes them into the filtrate. Secreted substances include H +, K +, NH 4 + (ammonium ion), creatinine (a waste product of muscle contraction), and various other substances (including penicillin and other drugs). Secretion occurs in portions of the PCT, DCT, and collecting duct.
Secretion of H +. Because a decrease in H + causes a rise in pH (a decrease in acidity), H + secretion into the renal tubule is a mechanism for raising blood pH. Various acids produced by cellular metabolism accumulate in the blood and require that their presence be neutralized by removing H +. In addition, CO 2, also a metabolic byproduct, combines with water (catalyzed by the enzyme carbonic anhydrase) to produce carbonic acid (H 2CO 3), which dissociates to produce H +, as follows:
CO 2 + H 2O ← → H 2CO 3 ← → H + + HCO 3 –
This chemical reaction occurs in either direction (it is reversible) depending on the concentration of the various reactants. As a result, if HCO 3 – increases in the blood, it acts as a buffer of H +, combining with it (and effectively removing it) to produce CO 2 and H 2O. CO 2 in tubular cells of the collecting duct combines with H 2O to form H + and HCO 3 –. The CO 2 may originate in the tubular cells or it may enter these cells by diffusion from the renal tubule, interstitial fluids, or peritubular capillaries. In the tubule cell, Na +/H + antiporters, enzymes that move transported substances in opposite directions, transport H + across the luminal membrane into the tubule while importing Na +. Inside the tubule, H + may combine with any of several buffers that entered the tubule as filtrate (HCO 3 –, NH 3, or HPO 4 2–). If HCO 3 – is the buffer, then H 2CO 3 is formed, producing H 2O and CO 2. The CO 2 then enters the tubular cell, where it can combine with H 2O again. If H + combines with another buffer, it is excreted in the urine. Regardless of the fate of the H+ in the tubule, the HCO 3 – produced in the first step is transported across the basolateral membrane by an HCO 3 –/Cl – antiporter. The HCO 3 – enters the peritubular capillaries, where it combines with the H + in the blood and increases the blood pH. Note that the blood pH is increased by adding HCO 3 – to the blood, not by removing H +.
- Secretion of NH 3. When amino acids are broken down, they produce toxic NH 3. The liver converts most NH 3 to urea, a less toxic substance. Both enter the filtrate during glomerular filtration and are excreted in the urine. However, when the blood is very acidic, the tubule cells break down the amino acid glutamate, producing NH 3 and HCO 3 –. The NH 3 combines with H +, forming NH 4 +, which is transported across the luminal membrane by a Na + antiporter and excreted in the urine. The HCO 3 – moves to the blood (as discussed earlier for H + secretion) and increases blood pH.
- Secretion of K +. Nearly all of the K + in filtrate is reabsorbed during tubular reabsorption. When reabsorbed quantities exceed body requirements, excess K + is secreted back into the filtrate in the collecting duct and final regions of the DCT. Because aldosterone stimulates an increase in Na +/K + pumps, K + secretion (as well as Na + reabsorption) increases with aldosterone. |
What is a Composting Toilet System and How Does it Compost?
Composting toilet systems (sometimes called biological toilets, dry toilets and waterless toilets) contain and control the composting of excrement, toilet paper, carbon additive, and, optionally, food wastes. Unlike a septic system a composting toilet system relies on unsaturated conditions (material cannot be fully immersed in water), where aerobic bacteria and fungi break down wastes, just as they do in a yard waste composter. Sized and operated properly, a composting toilet breaks down waste to 10 to 30 percent of its original volume. The resulting end-product is a stable soil-like material called "humus," which legally must be either buried or removed by a licensed seepage hauler in accordance with state and local regulations in the United States. In other countries, humus is used as a soil conditioner on edible crops.
The primary objective of the composting toilet system is to contain, immobilize or destroy organisms that cause human disease (pathogens), thereby reducing the risk of human infection to acceptable levels without contaminating the immediate or distant environment and harming its inhabitants.
This should be accomplished in a manner that
- is consistent with good sanitation (minimizing both human contact with unprocessed excrement and exposure to disease vectors, such as flies).
- produces an inoffensive and reasonably dry end-product that can be handled with minimum risk.
- minimizes odor.
A secondary objective is to transform the nutrients in human excrement into fully oxidized, stable plant-available forms that can be used as a soil conditioner for plants and trees.
The main components of a composting toilet are:
- a composting reactor connected to one or more dry or micro-flush toilets;
- a screened exhaust system (often fan-forced) to remove odors, carbon dioxide, water vapor, and the by-products of aerobic decomposition;
- a means of ventilation to provide oxygen (aeration) for the aerobic organisms in the composter;
- a means of draining and managing excess liquid and leachate;
- process controls, such as mixers, to optimize and manage the process; and
- an access door for removal of the end-product.
The composting reactor should be constructed to separate the solids from the liquids and produce a stable, humus material with less than 200 most probable number (MPN) per gram of fecal coliform.
General Types of Composting Toilet Systems
Composting toilet systems can be classified in several ways:
Self-Contained versus Centralized
Composting toilet systems are either self-contained, whereby the toilet seat and a small composting reactor are one unit (typically small cottage models), or centralized or remote, where the toilet connects to a composting reactor that is somewhere else.
Manufactured versus Site-Built
One can either purchase a manufactured composting toilet system or have a site-built composting toilet system constructed (however, the latter can be difficult to get permitted by local health agents).
Batch (Multiple-Chamber) versus Continuous (Single-Chamber)
Most composting toilet systems use one of two approaches to manage the composting process: either single-chamber continuous composting or multi-chamber batch composting processes
A continuous composter (including Clivus Minimuses and such brands as CTS, Clivus Multrum, Phoenix, BioLet, Sun-Mar) features a single chamber into which excrement is added to the top, and the end-product is removed from the bottom.
A batch composter (such as the EcoTech Carousel, all Vera systems, BioLet NE, and many site-built composters) utilizes two or more interchangeable composting reactors. One is filled at a time, then allowed to cure while another reactor fills, just as with two- and three-bin yard composters.
Proponents of continuous composting maintain that it is simple (takes place in one fixed reactor), allows urine to constantly moisten the process, and allows the center of the mass to heat up through uninterrupted microbial activity.
Advocates of the batch-composting approach say that by not continually adding fresh excrement and urine to older, more advance material, the material composts more thoroughly, uninterrupted by the added nutrients, pathogens, salts and ammonia in fresh excrement. Also, by dividing the material, it can have more surface area, and thus better aeration. Batch composting also offers an opportunity for unlimited capacity, as one simply adds compost reactors to the process to add capacity.
Batch systems require monitoring the level of the composter to determine when a chamber has filled and a new one must be moved into place. However, because there is more surface area and the material is divided, there is often less or no mixing and raking of the material.
What is true is that complete composting needs time to ecologically cascade all the by-products of the myriad organisms in the composting food web until all of the organic matter is finally transformed into safe, stable humus.
In continuous composters, urine or flush water can leach fresh excrement into the finished compost removal area. Segregating the material into batches reduces the risk of having living disease organisms in the finished products.
(One of the authors [Del Porto] has designed, sold and serviced both types of composters. He prefers batch composting-based systems, because they are more forgiving and users seem to be happier with them. However, he would never say that single-chamber continuous systems do not work. They do!
It is difficult to generalize about which process affords the greatest opportunity for complete processing and minimizes the potential for pathogen survival. In a batch system, a finite supply of nutrients is cycled and recycled through microbe populations until the nutrients, both the free ones and those bound in microbial protoplasm and cell walls, are ultimately converted to stable, fully oxidized forms, and the fungi have performed their work on the remaining lignin and cellulose compounds, releasing antibiotics in the process.
Definitive research is needed in this area.
Active versus Passive
As with solar systems, composting systems are usually either passive or active. Passive systems are usually simple moldering reactors in which ETPA (excrement, toilet paper and additive) is collected and allowed to decompose in cool environments without active process control (heat, mixing, aeration).
Active systems may feature automatic mixers, pile-leveling devices, tumbling drums, thermostat-controlled heaters, fans, and so forth. The trend in the composting of municipal solid waste (garbage and trash), sewage sludge and yard and agricultural residues is toward active systems. By making the process active, the size of the composter can be reduced, because composting efficiency is speeded up (and the volume of the material reduced faster).
Passive systems are designed to optimize the process by design, not mechanical action, allowing only time, gravity, ambient temperature and the shape of the container to control the process. Passive composters are often referred to as moldering toilets, as the process at work is natural uncontrolled decay at cool in-ground temperatures at or below 68° F. In this cool environment, molds (fungi and actinomycetes) are the primary biological decomposers, because it is a bit too cool for the faster-acting mesophilic and thermophilic bacteria. |
Each year, fires burn millions of hectares of forest worldwide.
The resulting loss and degradation of forested land is roughly equal to that caused by destructive logging and conversion to agriculture combined, and has wide-reaching consequences on biodiversity, health and the economy, among others.
Fires good and bad
Fire is sometimes essential for forest regeneration, or provides tangible benefits for local communities. In other cases it destroys forests and has dire social and economic consequences.
Forest fires are a natural part of ecosystems in many, but not all, forest types: in boreal and dry tropical forests for example they are a frequent and expected feature, while in tropical moist forests they would naturally be absent or at least rare enough to play a negligible role in ecology.
When fires become a problem…
Fires become a problem when they burn in the wrong places, or in the right places but at the wrong frequency or the wrong temperatures. Fires in forests that burn under natural circumstances become a problem when those forests are used for a particular purpose, such as settlement or timber production.
Pervasive human influence
Globally, most forest fires are probably now directly or indirectly influenced by humans. But in many areas that are hot and dry for part of each year, where frequent fires would be expected, human influence has now become so pervasive that most fires are ‘unnatural’.
Fires in a flux
Objectives and aims of fire management are not synchronized or thought-through, leading to unwanted and wanted fires, which can result in both beneficial and damaging effects. The geographical spread, frequency and intensity of fires are all changing.
Fire is also used as a management tool because it is cheap, simple to apply (particularly important if use is illegal) and sometimes the only option available for poorer people and smallholders.
Fires are usually signs of bigger, underlying problems. These underlying problems or factors include inappropriate economic incentives (such as subsidies for plantation agriculture) that stimulate the use of fire as a means of clearing forested land, inequitable or unclear land tenure leading to land and resource conflicts, failure to recognize or respect customary law, and weak or under-resourced government institutions.
Devastating to forests & humans
The immediate impact of forest fires can be devastating to human communities and forest ecosystems alike.
Fires can alter the structure and composition of forests, opening up areas to invasion by fast-colonizing alien species and threaten biological diversity.
Buildings, crops and plantations are destroyed and lives can be lost. For companies, fire can mean the destruction of assets; for communities, besides loss of an important resource base, fire can also lead to environmental degradation through impacts on water cycles, soil fertility and biodiversity; and for farmers, fire may mean the loss of crops or even livelihoods.
Severe forest fires, such as those in Indonesia in 1997/1998 and in Australia in 2001/2002, bring critical and in some cases life-threatening levels of pollutants. The health of as many as 75 million people may have been adversely affected by the Indonesian fires, with some 40,000 hospitalized for respiratory and other pollution-related ailments such as asthma, bronchitis and pneumonia, as well as eye and skin problems. The total cost of the fires was estimated at US$9.3 billion.
At the moment, action to combat forest fires only takes place when fires are burning, with rare attempts made to address the underlying causes.
Importance of local communities
Since government capacity is often lacking at local level, local communities are becoming increasingly involved in forest management and conservation, to the extent that many governments now expect communities to participate in managing fires.
- how long does a forest take to replenish itself after a deadly forest fire? (greenanswers.com)
- Forest Fire (jakesprinters.wordpress.com)
- Recent Wildfires In The World (disaster-report.blogspot.com)
- Perry County forest fire rages on as firefighters work into the darkness trying to quell the flames (pennlive.com) |
Our ocean covers 72% (and rising) of this small planet and is home to most of the globe's biomass, or living matter, and biodiversity. We know that from bacteria to plankton to the blue whale, life in the ocean greatly affects life on land, yet we know very little about the ocean. At least 80% is yet to be explored.
Conceptual computer artwork of the total volume of water on Earth (left) and of air in the Earth's atmosphere (right) shown as spheres (blue and pink). The spheres show how finite water and air supplies are. The water sphere measures 1,390 kilometres across and has a volume of 1.4 billion cubic kilometres. This includes all the water in the oceans, seas, ice caps, lakes and rivers as well as ground water, and that in the atmosphere. The air sphere measures 1,999 kilometres across and weighs 5,140 trillion tonnes. As the atmosphere extends from Earth it becomes less dense. Half of the air lies within the first 5 kilometres of the atmosphere.
This section of MarineBio explores some of what is known about the ocean and provides an online introduction to marine biology and ocean science. Here we begin the journey into this planet's largest living space—The Ocean.
The ocean is studied by separating it into different, though interrelated, scientific disciplines. To fully understand life in the sea we must consider the big picture: marine life and its interaction with its environment, as well as other life, including humans. The following sections will provide you with an overview of Marine Biology in terms of the physical, chemical, and biological marine environment. For a more thorough understanding of the following, we also recommend any of the outstanding Marine Biology textbooks we have listed on our book shop.
- The processes that have molded the ocean basins over billions of years.
- Ocean life is largely made up of the same chemicals that comprise the ocean.
Light & Color
- Sunlight in the sea and its interaction with ocean waters is a very important physical phenomenon...
Ocean & Temperature
- Ocean temperatures play vital roles in regulating our planet's climate and bringing nutrients to marine life.
Sounds of the Sea
- Sound travel underwater—the acoustics of the ocean. Can you hear me? Good...
Currents & Tides
- The effects and causes of the continuous flow of ocean water and its surface which is always rising and falling.
- Five "oceans" - Arctic, Atlantic, Indian, Pacific and Southern - covering ~71% of the Earth's surface...
Geological Makeup of Marine Environments
- Tectonic plates to the lives of creatures that exist in the most extreme environments.
- Beaches, intertidal, epipelagic, pelagic, and benthic zones... ecosystems for every imaginable creature.
Estuaries, Salt Marshes & Mangroves
- Vital ecosystems and nursing grounds for marine life.
- Where most marine life lives and almost all fishing takes place...
The Open Ocean
- Everything outside of coastal areas... the wild blue yonder...
Arctic & Antarctic
- Places of abundant life, lots of ice and the coldest places on Planet Ocean.
The Deep Sea
- The cold, dark, deep that makes up 80% of the ocean living space.
An ocean (from Greek Ωκεανός, Okeanos (Oceanus)) is a major body of saline water, and a principal component of the hydrosphere. Approximately 72% of the Earth's surface (~3.61 X 1014m2) is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas.
More than half of this area is over 3,000 meters (9,800 ft) deep. Average oceanic salinity is around 35 parts per thousand (ppt) (3.5%), and nearly all seawater has a salinity in the range of 30 to 38 ppt. Scientists estimate that 230,000 marine life forms of all types are currently known, but the total could be up to 10 times that number.
Though generally described as several 'separate' oceans, these waters comprise one global, interconnected body of salt water often referred to as the World Ocean or global ocean. This concept of a continuous body of water with relatively free interchange among its parts is of fundamental importance to oceanography.
The major oceanic divisions are defined in part by the continents, various archipelagos, and other criteria. These divisions are (in descending order of size):
- Pacific Ocean, which separates Asia and Australia from the Americas
- Atlantic Ocean, which separates the Americas from Eurasia and Africa
- Indian Ocean, which washes upon southern Asia and separates Africa and Australia
- Southern Ocean, the southern portions of the Pacific, Atlantic, and Indian Oceans, which encircles Antarctica and covers much of the Antarctic
- Arctic Ocean, sometimes considered a sea of the Atlantic, which covers much of the Arctic and borders northern North America and Eurasia
Geologically, an ocean is an area of oceanic crust covered by water. Oceanic crust is the thin layer of solidified volcanic basalt that covers the Earth's mantle. Continental crust is thicker but less dense. From this perspective, the earth has three oceans: the World Ocean, the Caspian Sea, and Black Sea. The latter two were formed by the collision of Cimmeria with Laurasia. The Mediterranean Sea is at times a discrete ocean, because tectonic plate movement has repeatedly broken its connection to the World Ocean through the Strait of Gibraltar. The Black Sea is connected to the Mediterranean through the Bosporus, but the Bosporous is a natural canal cut through continental rock some 7,000 years ago, rather than a piece of oceanic sea floor like the Strait of Gibraltar.
Despite their names, smaller landlocked bodies of saltwater that are not connected with the World Ocean, such as the Aral Sea, are actually salt lakes.
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|Adding an acid or a base to a buffer solution is the same as carrying out a titration. We discuss the pH changes in a buffer solutions using titration of weak acid by a strong base.|
The blood is a natural buffer, and so are other body fluids and plant fluids due to mixtures of weak acids and bases present in them.
On this page, we explore the reasons why the pH of buffer solutions resists to change.
Buffer solutions are required for many chemical experiments. They are also useful to standardize pH meters. Thus, there are many suppliers of buffer solutions.
There are also computer programs available to help design and make buffer solutions on the internet. For example:
We illustrate the titration of a weak acid by a strong base using the following examples.
During the titration process and before the equivalent point is reached, some acid has been neutralized by the strong base, and the solution contains a weak acid and its salt. The solution acts as a buffer.
(What is the pH of a Ca M weak acid before starting the titration?)
Let HA represent the weak acid, and assume x M of it is ionized. Then, the ionization and equilibrium concentration is
HA = H+ + A- Ca-x x x x2 Ka = ------ Ca-x x2 + Kax - CaKa = 0 -Ka + (Ka2 + 4 CaKa)1/2 x = --------------------- 2 pH = -log(x)
The method has been fully discussed in Weak acids and bases equilibrium. Symbols are used here, but approximations may be applied to numerical problems.
After mixing, the concentrations Ca and Cs of the acid HA and its salt NaA respectively are
HA = H+ + A- Ca-x x x NaA = Na+ + A- Cs Cs Common ion [A-] = x+Cs x(x+Cs) Ka = -------- Ca-x x2 + (Ka+Cs)x - Ca Ka = 0 -(Ka+Cs) + ((Ka+Cs)2 + 4 Ca Ka)1/2 x = ----------------------------- 2 pH = -log(x)
The formulas for x and the pH derived above can be used to estimate the pH of any buffer solution, regardless how little salt or acid is used compared to their counter part.
When the ratio Ca / Cs is between 0.1 and 10, the Henderson-Hasselbalch equition is a convenient formula to use.
[H+] [A-] Ka = ---------- [HA] [A-] pKa = pH - log (----) [HA]The Henderson-Hasselbalch equation is
[A-] pH = pKa + log (----) [HA] [Cs] + x = pKa + log (----) [Ca] - xBecause when x is insignificant in comparision to Cs, [A-] = Cs and [HA] = Ca
[H+] pH See
0.0 mL 0.00316 2.500 A.
0.1 9.07e-4 3.042 B.
1.0 9.07e-5 4.042 C.
5.0 1.0e-5 5.000 D.
10.0 10-11.349 11.349 E.
Note the sharp increase in pH when 0.1 mL (3 drops) of basic solution is added to the solution.
HA = H+ + A- Ca-x x x [A-] = x + 0.0099 (= Cs) x (x + 0.0099) Ka = -------------- = 1e-5 0.98 - x x2 + 0.0099 x = 9.8e-6 - 1e5 x x2 + (0.0099 + 1e5) x - 9.8e-6 = 0 x = (-0.0099 + (0.00992 + 4*0.98*1e-5)1/2) / 2 = 0.000907 pH = 3.042
Note that using the Henderson-Hasselbalch equation will not yield the correct solution. Do you know why?
HA = H+ + A- Ca-x x x+0.0901 x (x + 0.0901) Ka = -------------- = 1e-5 0.818 - x x = (-0.0901 + (0.09012 + 4*0.818*1e-5)1/2) / 2 = 0.0000907 (any approximation to be made?) pH = 4.042Using the Henderson Hasselbalch equation yield
0.0901(=[A-]) pH = pKa + log (------) = 5 - 0.958 = 4.042 (same result) 0.818(=[HA])
HA = H+ + A- Ca-x x x+0.3333 x (x + 0.333) Ka = -------------- = 1.0e-5 0.333 - x x 2 + (0.333-1e-5)x - 0.333*1e-5 = 0 x = (-0.333 + (0.3332 + 4*3.33e-6)1/2) / 2 = 0.0000010 pH = 5.000
Note: Using the Henderson Hasselbalch equation yield the same result
0.333(=[A-] pH = pKa + log (----) = 5 + 0.000 = 5.000 0.333(=[HA])
A- + H2O = HA + OH- Cs-x x x Equilibrium concentrations [HA] [OH-] [H+] Kb = ---------- ---- [A-] [H+] Kw 1e-14 x 2 = --- = ----- = 1e-9 = ------ Ka 1e-5 Cs-x x = (0.500*1.0e-9)1/2 = 2.26e-5 pOH = -log x = 2.651; pH = 14 - 2.651 = 11.349
Note: The calculation here illustrate the hydration or hydrolysis of the basic salt NaA.
Sketch the titration curve based on the estimates given in this example, and notice the points made along the way.
Learn it by doing! Perform all the calculations outlined in Example 3, and then you will be an expert for solving buffer and hydration problems.
The following relationship is handy to use, but make sure you know why
Kb = Kw / Ka = ?
What is the pH at the equivalence point when a 0.10 M HF solution is titrated by a 0.10 M NaOH solution?
A simple consideration leads to the formulation:
[Na+] = [F-] = 1.0 mL * 0.10 M / 11.0 mL
Answer pH = pKa = 3.17
What is the pH of the equivalence point during the titration of 0.10 M HF using 0.10 M NaOH solution? (Another way of asking the same question.) |
Logging’s roots in America stretch back to the early 1600s. Ever since the arrival of settlers in Jamestown in 1607, lumber has been essential to the North American economy. Today, the logging trade is an enormous global business, and it continues to be driven by ambitious workers willing to take on one of the world’s most dangerous jobs.
At first, lumber played a key role in shipbuilding; later, with the advent of the Industrial Revolution, demand increased exponentially. By the early 1830s, Bangor, Maine, was the world’s biggest shipping port for lumber. Around the start of the 20th century, with the timber supply in the Midwest dwindling, the Pacific Northwest emerged as a logging center, and it remains an important source of timber to this day.
Methods and techniques for cutting and moving lumber have evolved over time. In the early days, loggers cut timber near water, which helped them transport the wood they harvested. As they moved further inland, loggers relied on horses and oxen to haul lumber, dragging logs through the woods over skid roads and rough tracks. They also developed log flumes, which transported lumber in water-filled troughs, and the log driving method, in which they guided logs down streams and tied them together into rafts. Another technique involved constructing a makeshift railroad from the very lumber it was designed to transport. No matter what their mode of transportation, the logs were sent to sorting yards once they reached a main waterway. They then moved on to mills, where they were transformed into products, or exported as far away as Australia and China.
Working in all-male crews, loggers wielded axes and handsaws; later, they would use chainsaws and harvesting machines such as the feller-buncher. They developed their own unique vocabulary, made up of terms like “faller” (a worker who felled trees) and “bucker” (a worker who cut them into pieces). Throughout the 19th century and in the beginning of the 20th, loggers lived a rugged existence on remote camps near their worksites, battling long hours, hard labor and rough accommodations. Lice and disease were persistent problems, and it wasn’t uncommon for loggers to wear the same clothes for months on end. Over time, labor unions would demand better conditions, and the camps evolved into communities where families lived and thrived. |
IT is one of life’s great enigmas: why do we sleep? Now we have the best evidence yet for the function of sleep – that it lets housekeeping processes take place to stop our brains becoming overloaded with new memories.
As far as we know, every animal sleeps (see “Why snooze?“), but the reason for their slumber has remained elusive. When lab rats are deprived of sleep, they die within a month, and when people go for a few days without sleeping, they start to hallucinate and may have epileptic seizures.
One idea is that sleep helps us consolidate new memories, as people do better in tests if they get a chance to sleep after learning. We know that, while awake, fresh memories are recorded by reinforcing connections between brain cells, but the memory processes that take place while we sleep have been unclear.
Support is growing for a theory that sleep evolved so that connections between neurons in the brain can be whittled down overnight, making room for fresh memories to form the next day. “Sleep is the price we pay for learning,” says Giulio Tononi at the University of Wisconsin-Madison, who developed the idea.
Now we have the most direct evidence yet that he is right. Tononi’s team measured the size of these connections, or synapses, in the brains of 12 mice. The synapses in samples taken at the end of a period of sleep were 18 per cent smaller than those in samples taken before sleep, showing that the connections between neurons weaken during slumber.
“By pruning down connections between brain cells, sleep is the price we pay for learning“
Tononi announced these findings at the Federation of European Neuroscience Societies meeting in Copenhagen, Denmark, last week. “The data was very solid and well documented,” says Maiken Nedergaard at the University of Rochester, New York, who attended the conference.
“It’s an extremely elegant idea,” says Vladyslav Vyazovskiy at the University of Oxford.
If the housekeeping theory is right, it would explain why, when we miss a night’s sleep, we find it harder the next day to concentrate and learn new information – we may have less capacity to encode new experiences. Tononi’s finding also suggests that, as well as sleeping well after learning something new, we should also try to sleep well the night before.
The idea could also explain why, if our sleep is interrupted, we feel less refreshed the next day. There is some indirect evidence that deep, slow-wave sleep is best for shrinking down synapses, and it takes time for our brains to reach this level of unconsciousness.
Keeping what matters
Because memories are stored by new synapses, and sleep seems to consolidate new memories, the idea that sleep weakens, rather than strengthens, brain connections might seem counterintuitive.
But there is previous evidence to support the housekeeping theory. For instance, EEG recordings show that our brains are less electrically responsive at the start of the day – after we have slept well – than at the end, suggesting that the connections may be weaker.
And at the start of their wakeful periods, rats have lower levels of a molecule called the AMPA receptor, which is involved in the functioning of synapses.
The latest finding, that synapses get smaller during sleep, is the most direct evidence yet that the housekeeping theory is right, says Vyazovskiy. “Structural evidence is very important,” he says. “That’s much less affected by other confounding factors.”
Gathering this data was a Herculean task, says Tononi. The team collected tiny chunks of brain tissue from 12 mice that had either been awake or asleep, sliced it into ultra-thin sections and used these to create 3D models of the brain tissue to identify the synapses. As there were nearly 7000 synapses, it took seven researchers four years.
The team did not know which mouse was which until last month, says Tononi, when they broke the identification code, and found that their theory stood up.
“People had been working for years to count these things,” says Tononi. “You start having stress about whether it’s really possible for all these synapses to start getting fatter and then thin again.”
Their research also hints at how we may build lasting memories over time, despite this thinning. The team discovered that some synapses seem to be protected – the biggest fifth stayed the same size. It’s as if the brain is preserving its most important memories, says Tononi. “You keep what matters.”
From worms to blue whales, all 230 animal species studied so far catch some shut-eye. Even dolphins and some birds, which we thought did not sleep as they are constantly on the move, are now known to send one half of their brain to sleep at a time.
If our bodies just needed physical rest, we could do this without falling unconscious. “Why would we spend several hours a day at the mercy of predators without doing some useful function?” asks Giulio Tononi at the University of Wisconsin-Madison.
Most theories, including Tononi’s (see main story), involve some kind of brain housekeeping or repair, but until recently no compelling candidates had emerged for what changes inside the brain during sleep.
But recently a “drainage system” was discovered, similar to the lymph vessels that drain waste products from tissues in the rest of the body. This ramps up when we sleep, suggesting that waste products are being cleared away while we slumber.
Alternative theories suggest the purpose of sleep is to conserve energy or keep animals out of harm’s way while food is unavailable. And of course it is possible that sleep could be performing several functions at once, or may even have different purposes in different animals.
This article appeared in print under the headline “Solving the mystery of sleep” |
Definition of an exothermic reaction, the role of energy and examples of exothermic reactions.
A presentation on exothermic versus endothermic reactions based on bond breaking and bond forming.
Reviews the definition and examples of exothermic reactions.
Summarize the main idea of a reading, create visual aids, and come up with new questions using a Four Square Concept Matrix.
Explore what happens to the energy of reactions. |
Normal pressure hydrocephalus (NPH) is a type of hydrocephalus that occurs in adults, usually older adults. The average age of people with NPH is older than 60 years.
NPH is different to other types of hydrocephalus in that it develops slowly over time. The drainage of CSF is blocked gradually, and the excess fluid builds up slowly. The slow enlargement of the ventricles means that the fluid pressure in the brain may not be as high as in other types of hydrocephalus.
The parts of the brain most often affected in NPH are those that control the legs, the bladder, and the ‘cognitive’ mental processes such as memory, reasoning, problem solving, and speaking.
This decline in mental processes, if it is severe enough to interfere with everyday activities, is known as dementia. Other symptoms include abnormal gait (difficulty walking), inability to hold urine (urinary incontinence), and, occasionally, inability to control the bowels.
Note: The symptoms of NPH can be similar to those of diseases such as Alzheimer's and Parkinson's. Experts believe that many cases of NPH are misdiagnosed as one of these diseases.
What causes NPH?
Normal pressure hydrocephalus can occur after a head injury, bleeding around the brain (due to a blow to the head), stroke, meningitis (infection of a protective layer of tissue around the brain), or brain tumour. It can also happen after surgery on the brain. How these conditions lead to NPH is not clear. In most cases, the cause of NPH is never fully known. |
FIRE CAUSES AND PREVENTION
is the rapid oxidation
of a material in the exothermic
chemical process of combustion
, releasing heat
, and various reaction products
. Fire in its most common form can result in conflagration
, which has the potential to cause physical damage through burning
FEATURES OF FIRE
Listed below are 9 common sonic features of fire and their causes.
1) lapping - combustion of gasses in the air (flames)
2) cracking - small scale explosions caused by stresses in the fuel
3) hissing - regular outgassing, release of trapped vapour
4) bubbling - boiling of liquids
5) creaking - internal stress of fuel expansion or nearby structures
6) fizzing - ariel conflagration of small particles
7) whining - periodic relaxations during outgassing
8) roaring - low frequency O2 cycle
9) clattering - settling of fuel under gravity
refers to precautions that are taken to prevent or reduce the likelihood of a fire
that may result in death, injury, or property damage, alert those in a structure to the presence of an uncontrolled fire
in the event one occurs, better enable those threatened by a fire to survive in and evacuate from affected areas, or to reduce the damage caused by a fire. Fire safety measures include those that are planned during the construction
of a building or implemented in structures that are already standing, and those that are taught to occupants of the building.
is the act of extinguishing fires
. A firefighter
fights fires to prevent loss of life, and/or destruction of property and the environment. Firefighting is a highly technical skill that requires professionals who have spent years training in both general firefighting techniques and specialized areas of expertise.
Fire Fighting Equipment are the tools and gear used to put out fire. Below is a list of the most common equipment used. Bungendore Rural Services supplies these products to the Palerang and ACT regions.
1) Fire Fighting Blankets: The use of a blanket in putting out a fire is to deprive it of oxygen and stifle it. A blanket can be put over a car to prevent the fire from spreading to others. A blanket can also be used on a person who has caught fire to put it off and prevent further injuries.
2) Fire Hose: This is a high pressurised hose used by fire fighters to put out fire. The hose is used to carry foam or water. The hose can be attached to a fire hydrant or engine when putting out a fire outdoors or a building standpipe indoors.
3) Fire Nozzles: They enable fire fighters to control the flow rate and pressure of water or the foam being used to put out the fire.
4) Fire Hose Couplings: These are metal pieces that are put at the end of a fire hose to enable it to connect to another fire hose or hose equipment. Couplings are normally made of aluminium, brass, stainless steel and come in many different designs.
5) Automatic Sprinkler: It directs water automatically to a fire after the sprinkler is heated. The pipe normally is filled with pressurised water or foam depending on the type of fire being put out.
is a function of many fire departments
. The goal of fire prevention is to educate the public to take precautions to prevent potentially harmful fires
, and be educated about surviving them.
The following important aspects of fire safety program;
1) Install a smoke alarm on every level. Change the batteries at least once a year. Better yet, grab a pack of whatever batteries your smoke alarm requires at a warehouse store like Costco or Sam’s Club. Therefore, when they beep to be changed, your default reaction isn’t to take out the battery but to replace the battery.
2) Keep anything that’s flammable away from stove, including pot holders, drapes, paper towels and kitchen towels.
3)Keep clutter away from any type of heater or furnace. For example, never store newspapers or family photos around a furnace. One loose spark could start a large fire in minutes.
4) One of the number one causes of fire are clothes dryers. The # 1 way to prevent fires starting is to clean the lint trap after every use.
5) Install carbon monoxide detectors throughout home, especially in bedrooms. Carbon monoxide is odorless and colorless, and very combustible.
6) Any outdoor cooking such as grilling or deep frying should be done at least ten feet from the house.
7) Hide any matches and lighters away from children.
8) Never overload an extension cord or outlet. In addition, make sure all cords don’t contain any frayed wiring. |
Remote sensing and measurements of the Moon from Apollo orbiting spacecraft and Earth form a basis for extrapolation of Apollo surface data to regions of the Moon where manned and unmanned spacecraft have not been and may be used to discover target regions for future lunar exploration which will produce the highest scientific yields. Orbital remote sensing and measurements discussed include (1) relative ages and inferred absolute ages, (2) gravity, (3) magnetism, (4) chemical composition, and (5) reflection of radar waves (bistatic). Earth-based remote sensing and measurements discussed include (1) reflection of sunlight, (2) reflection and scattering of radar waves, and (3) infrared eclipse temperatures. Photographs from the Apollo missions, Lunar Orbiters, and other sources provide a fundamental source of data on the geology and topography of the Moon and a basis for comparing, correlating, and testing the remote sensing and measurements.
Relative ages obtained from crater statistics and then empirically correlated with absolute ages indicate that significant lunar volcanism continued to 2.5 b.y. (billion years) ago-some 600 m.y. (million years) after the youngest volcanic rocks sampled by Apollo-and that intensive bombardment of the Moon occurred in the interval of 3.84 to 3.9 b.y. ago. Estimated fluxes of crater-producing objects during the last 50 m.y. agree fairly well with fluxes measured by the Apollo passive seismic stations.
Gravity measurements obtained by observing orbiting spacecraft reveal that mare basins have mass concentrations and that the volume of material ejected from the Orientale basin is near 2 to 5 million km 3 depending on whether there has or has not been isostatic compensation, little or none of which has occurred since 3.84 b.y. ago. Isostatic compensation may have occurred in some of the old large lunar basins, but more data are needed to prove it.
Steady fields of remanent magnetism were detected by the Apollo 15 and 16 subsatellites, and the lunar dipole field was revised to no more than 6x 10 19 gauss. High-resolution mapping of fields of weak remanent magnetism (to 0.1 gamma) was made possible by the Apollo plasma and energetic-particle experiment. Although the causes of remanent magnetism are poorly understood, correlations with geologic units suggest the results may ultimately have farreaching significance to lunar history. Maria are much less structured by strong surface magnetic anomalies than the highlands. The strongest anomalies are associated with ejecta of farside basins, plains materials filling pre-Imbrian craters, and other old Imbrian to pre-Imbrian units. The high remanent fields could be due to cooling of ejecta units in an ancient magnetic field, lunar regolith maturity, extensive reworking and disruption of a magnetized layer, or simply surface roughness.
Orbital geochemical experiments have shown that lunar high lands have larger Al: Si ratios and smaller Mg: Si ratios than maria. These two ratios are inversely related on a regional basis. With the exception of fresh craters, albedo and Al : Si ratios vary directly, showing that compositional differences as well as exposure of fresh materials are responsible for high albedos. Statistically treated data show that geologic contacts and compositional boundaries are concentric and can be roughly matched. Some craters on mare material have penetrated the mare fill, bringing highland-type materials to the surface. Natural radioactivity from thorium, potassium, and uranium is inversely correlated with elevation. Mare regions are enriched in iron, titanium, and magnesium relative to the highlands.
Orbital bistatic-radar results provide estimates of surface roughness at two scale lengths (about 30 m and 250 m), which agree with visual estimates of roughness. The dielectric constant of the lunar surface, where sampled, is uniform to 13-cm radar and near 3. Slope frequency distributions measured by the radar vary and |
This packet includes a classroom experiment and a take home lab to encourage parent involvement. Students will use their sense of hearing to observe sounds around them. The students are encouraged to participate in a show-n-tell sound share. All resources are included to set up the experiments. Students will be observing, collecting data, comparing, contrasting, drawing and writing during the labs. These activities are standard based for kindergarten and first grade. Thank you for looking!
For a complete 5 senses unit visit my blog: |
In the spring, trees are the primary source of airborne pollen. During the summer, grasses take the lead role, followed in the late summer and fall by weed pollen, including the dreaded ragweed.
The following five plants are among the worst offenders when it comes to spring allergies. Why? Because they rely on wind, not on insects, to disperse pollen. As a result, they produce a lot of it to increase the chances that grains will reach and fertilize a female flower.
PSU Entomology/Photo Researchers
Of course, all that airborne pollen also means more of it is likely to reach your nose and eyes. Read "10 Tips to Reduce Your Exposure" for ways to manage spring allergies.
Visuals Unlimited/Getty Images
Mountain Cedar and Eastern Red Cedar
"There are vast populations in central Texas, literally hundreds of thousands of acres are covered with mountain cedar trees. It is a major, major allergen there," says Estelle Levetin, chair of the Aerobiology Committee of the American Academy of Allergy, Asthma & Immunology and professor of biology at the University of Tulsa. The severity of cedar allergies in that region has spawned a movement, "People Against Cedars," to control the spread of the tree. If you live on the East Coast, you may be sensitive to its close relative, the Eastern red cedar (pictured above).
When does it peak? Mountain cedar: December through March; Eastern red cedar: February through April
Where does it grow? Mountain cedar grows in rocky, dry soil in the Southwestern United States (mainly Texas, southern Oklahoma, Arkansas and northern Mexico). Eastern red cedar prefers moist soils and can be found in states on the East Coast and in the Midwest.
Maria Mosolova/Photo Researchers
The oak's hanging catkins, tassel-like appendages that are a few inches long, bear clusters of male flowers. Once these flowers disperse pollen, the catkins fall off the tree — you may have seen them on the sidewalk or piled up on your car's windshield in the spring. Pollen from the catkins fertilizes the oak's female flower to produce acorns. If you're allergic to oak, you may also be sensitive to beech, birch and alder trees, which are in the same family.
When does it peak? February through May
Where does it grow? Throughout the United States
The elm’s graceful vase-shape made it a popular shade tree for city streets. Although elms have been hit hard by Dutch elm disease over the last century, says Dr. Levetin, "it is still an important tree is many parts of the country, [so] we still see a lot of elm pollen in the air."
When does it peak? February to April (white elm or American elm), some species flower in the fall
Where does it grow? Eastern and Central United States
James Randklev/Getty Images
This is the tallest species of alder in North America, and the wood’s red tannin has been used as a dye. If you're allergic to alder, you may also have sensitivity to beech, birch and oak trees, which are in the same family.
When does it peak? February through April
Where does it grow? Cool and moist areas in the Western United States
James Randklev/Getty Images
Sweet Vernal Grass
Although summer is peak season for grass pollen, vernal is an early-blooming grass and is behind the sweet smell of freshly mown hay, according to The Encyclopedia of Herbs. The plant contains the natural compound coumarin, which is responsible for the grass's vanilla-like fragrance when cut and dried.
When does it peak? April to July
Where does it grow? In fields and on roadsides throughout the United States |
Actually, Sherlock Holmes said, “Elementary, my dear Watson,” but it’s close. A collection of 118 existing elements are detailed on the periodic table and range from the most versatile, carbon, to the funny-sounding ytterbium. But what makes each element unique? The answer is actually fairly simple: the number of protons, neutrons and electrons.
When an element has the same number of protons and electrons but a different number of neutrons, it’s called an isotope. Some isotopes are stable and others last only a few nanoseconds.
Elements behave in many different ways. Some have different melting temperatures and some, like hydrogen, helium, nitrogen, oxygen and others, are gases. For instance, to turn helium (He) into a liquid you need to cool it down to -272oC. (The lowest temperature ever recorded on Earth is -89.2oC in Antarctica.) Some elements, like mercury, are liquids at room temperature. Many are solids and some, like molybdenum (Mo), have a melting temperature of 2617oC. By comparison, French fries cook at 400F, or about 204C.
The number of electrons and where they are located is important and determines the properties of the elements. Some elements, like copper (Cu), are good conductors, meaning that their properties permit the easy movement of electrons, which creates energy in the form of heat. Others, though, like sulfur (S), are better insulators because their properties prohibit or hinder the movement of electrons so they don’t tend to heat up.
Some really neat elements are called semiconductors because sometimes they conduct electrons and other times they don’t. One famous semiconductor is silicon (Si), which, depending on what other molecules are around, can sometimes act as an insulator and other times as a conductor.
But perhaps the most versatile of all the elements is carbon (C), which can do all sorts of things like be made into diamonds, the kind of graphite we find in pencils, and even some of the coolest nanoelectronics circuits. |
HIV (human immunodeficiency virus) is the virus that causes AIDS (acquired immunodeficiency syndrome). HIV attacks the body's immune system. The immune system is the body's defense against infections. Over time, HIV weakens the body’s ability to fight serious infections and some cancers. When this happens, HIV infection becomes AIDS. AIDS can be life threatening, but it is also a preventable disease.
HIV spreads from person to person when infected blood or sexual secretions, such as semen, enter the body. Men, women, and children of all ages can get HIV. You can get infected with HIV through:
HIV is not spread through the air, in food, or by casual social contact such as shaking hands or hugging.
Babies can get infected before they are born or from the breast milk of an infected mother.
A baby born with HIV often has no signs of HIV infection at birth. When infected babies are 2 to 3 months old, they may start having problems, such as:
A child with HIV tends to get more infections, and get sicker than other children from common infections like the flu.
Teens who get HIV may not have symptoms at the time of infection. It may take years for symptoms to show. During this time, they can spread the virus to others without knowing they have the virus.
When symptoms start, they are usually the symptoms of the other diseases that are able to attack the body because of a weak immune system, such as:
HIV is diagnosed with blood tests.
Medicines can slow down the disease, but they are not a cure. Your child may need to have blood tests every few weeks or months to see how the virus is affecting his or her body and how well the treatment is working. Treatment for HIV/AIDS may include treatment or prevention of other infections and tumors.
To work properly, anti-HIV drugs need to be taken at the right time and in the right way. This can be hard for children. Kids may not want to take bad-tasting medicines or may not want to take medicines in front of other people. Talking with your healthcare provider and support groups can help.
Some immunizations may be different for babies or children with HIV/AIDS. Children whose immune systems are very weak will not be given live virus vaccines, such as measles-mumps-rubella (MMR), varicella (chickenpox), rotavirus, and flu vaccines that use a live virus.
If your child has HIV or AIDS, here are some things you can do to take care of your child and help prevent problems.
Follow the full course of treatment prescribed by your healthcare provider. In addition:
Ask your provider:
At this time, there is no vaccine to prevent HIV and AIDS. For now, you can help to protect your children from HIV by doing these things:
You can get more information from: |
Counting Down to the New Ampere
In 2018, the base units of the International System of Units (SI) are scheduled to be re-defined in terms of physical constants, with major changes in the kilogram, ampere, kelvin, and mole.
After it’s all over, your lights will be just as bright, and your refrigerator just as cold. But very soon the ampere — the SI base unit of electrical current — will take on an entirely new identity, and scientists at the U.S. National Institute of Standards and Technology (NIST) are among those at work on an innovative, quantum-based measurement system that will be consistent with the impending change.
In the “New SI” four of the SI base units – namely the kilogram, the ampere, the kelvin and the mole – will be redefined in terms of constants; the new definitions will be based on fixed numerical values of the Planck constant (h), the elementary charge (e), the Boltzmann constant (kB), and the Avogadro constant (NA), respectively.
Further, the definitions of all seven base units of the SI will also be uniformly expressed using the explicit-constant formulation, and specific mises en pratique will be drawn up to explain the realization of the definitions of each of the base units in a practical way.
This animation demonstrates how a single electron transport (SET) device works. Electrons flow across the device from the “source” to the “drain.” A region of silicon between the gates — called an “island” — is used to briefly store single electrons.
By controlling the voltages of two gates, researchers can influence the electrons’ movement, so that a single electron remains in the island before tunneling into the drain. By repeating this process at a high rate, many electrons flow one at a time across the device, providing a source of current.
It won’t be a minute too soon. The ampere (A) has long been a sort of metrological embarrassment. For one thing, its 70-year-old formal definition, phrased as a hypothetical, cannot be physically realized as written:
The ampere is that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed 1 meter apart in vacuum, would produce between these conductors a force equal to 2 x 10-7 newton per meter of length.
For another, the amp’s status as a base unit is problematic. It is the only electrical unit among the seven SI base units. So you might logically expect that all other electrical units, including the volt and the ohm, will be derived from it. But that’s not the case.
In fact, the only practical way to realize the ampere to a suitable accuracy now is by measuring the nominally “derived” volt and ohm using quantum electrical standards and then calculating the ampere from those values. Josephson voltage and quantum Hall effect resistance can be determined via quantum constants to uncertainties of parts per billion or less.
In 2018, however, the ampere is slated to be re-defined in terms of a fundamental invariant of nature: the elementary electrical charge (e). The charge of a single electron will be fixed at a value of 1.60217X × 10-19 ampere-second, where “X” will be specified at the time of the redefinition. One ampere-second is the same as one coulomb. Direct ampere metrology will thus become a matter of counting the transit of individual electrons over time.
One promising way to do so is with a nanoscale technique called single-electron transport (SET) pumping. Specially adapted at NIST for this application, it involves applying a gate voltage that prompts one electron from a source to tunnel across a high-resistance junction barrier and onto an “island” made from a microscopic quantum dot. (See animation above.)
The presence of this single extra electron on the dot electrically blocks any other electron from tunneling across until a gate voltage induces the first electron to move off the island, through another barrier, and into a drain. When the voltage returns to its initial value, another electron is allowed to tunnel onto the island; repeating this cycle generates a steady, measurable current of single electrons.
There can be multiple islands in a very small space. The distance from source to drain is a few micrometers, and the electron channels are a few tens of nanometers wide and 200 nm to 300 nm long. And the energies involved are so tiny that that device has to be cooled to about 10 millikelvin in order to control and detect them reliably.
Conventional, metallic SET devices, says NIST quantum-ampere project member Michael Stewart, can move and count single electrons with an uncertainty of a few parts in 108 — in the uncertainty range of other electrical units — at a rate of tens of millions of cycles per second. “But the current in a single SET pump is on the order of picoamperes [10-12 A],” he says, “and that’s many orders of magnitude too low to serve as a practical standard.”
So Stewart, colleague Neil Zimmerman, and co-workers are experimenting with ways to produce a current 10,000 times larger. By using all-silicon components instead of conventional metal/oxide materials, they believe that they will be able to increase the frequency at which the pump can be switched into the gigahertz range.
And by running 100 pumps in parallel and combining their output, the researchers anticipate getting to a current of about 10 nanoamperes (10-9 A). Another innovation under development may allow them to reach a microampere (10-6 A), in the range that is needed to develop a working current standard.
“At present, we are testing three device configurations of different complexity,” Stewart says, “and we’re trying to balance the fabrication difficulties with how accurate they can be.”
In addition to its use as an electrical current standard, a low-uncertainty, high-throughput SET pump would have two other significant benefits. The first is that it might be combined with ultra-miniature quantum standards for voltage or resistance into a single, quantum-based measurement suite that could be delivered to factory floors and laboratories. The overall effort to provide such standards for all the SI base units is known as “NIST-on-a-Chip,” and is an ongoing priority of NIST’s Physical Measurement Laboratory.
The other advantage is that an SET pump could be used in conjunction with voltage and resistance standards to test Ohm’s Law. Dating from the 1820s, it states that the amount of current (I) in a conductor is equal to the voltage (V) divided by the resistance (R): I=V/R. This relationship has been the basis for countless millions of electrical devices over the past two centuries. But metrologists are interested in testing Ohm’s law with components which rely on fundamental constants. An SET pump could provide an all-quantum mechanical environment for doing so.
In a separate effort, scientists at NIST’s Boulder location are experimenting with an alternative technology that determines current by measuring the quantum “phase-slips” they engender while traveling through a very narrow superconducting wire. That work will be the subject of a later report. |
Image credit: Chandra
A new image released from the Chandra X-Ray Observatory shows a glowing shell of gas created by the explosion of a massive star. The supernova remnant is called N63A, and thought to be 2,000 to 5,000 years old; it’s located in the Large Magellanic Cloud. A comparison of this image with optical and radio observations show that the shockwave of material is engulfing the entire cloud of material, heating it up to ten million degrees Celsius.
Chandra has imaged the glowing shell created by the destruction of a massive star. X-rays from Chandra (blue), combined with optical (green) and radio (red) data, reveal new details in the supernova remnant known as N63A, located in the nearby galaxy of the Large Magellanic Cloud.
The X-ray glow is from material heated to about ten million degrees Celsius by a shock wave generated by the supernova explosion. The age of the remnant is estimated to be in the range of 2,000 to 5,000 years.
Optical and radio light are brightest in the central region of the remnant, which appears as a triangular-shaped “hole” in the X-ray image. The hole is produced by absorption of X-rays in a dense cloud of cooler gas and dust on the side of the remnant nearest the Earth. A comparison of the X-ray image with the radio and optical images suggests that the shock wave is engulfing this massive cloud, so we see only the edge nearest the Earth. Collisions such as this are thought to trigger the formation of new generations of stars.
The fluffy crescent-shaped X-ray features that appear around the edge of the remnant are thought to be fragments of high-speed matter shot out from the star when it exploded, like shrapnel from a bomb. In the only other supernova remnant (the Vela supernova remnant) where such features have been observed, the crescent shapes are clearly produced by ejecta fragments. An alternative explanation is that they were produced when the shock wave swept over less-massive clouds located several light years away from the site of the explosion.
Original Source: Chandra News Release |
What is 3D Printing?
3D Printing or Additive Manufacturing is the process of making a solid object from a digital CAD file. This solid model can be achieved in a number of ways but all involve splitting the CAD file into many layers. These layers are then printed by laying down your chosen material on top or below of each other to create the final model.
3D Printing is disrupting traditional manufacturing methods as you have very little waste from machining, overflow etc and in many cases can be quicker to manufacture. As such, you can produce prototypes or functional parts with much less material wastage than traditional methods. |
Python supports manipulation of anonymous functions (i.e. lambda expressions). Lambda functions is a way to create functions without names. These functions are throwaway functions and are used where they are created. These anonymous functions are handy to use in a places where you can’t do function declaration.
- Lambda lets you define and use a function inside an if statement, or inside a python list.
- Lambda expressions can be used in a places where you can’t use function declaration.
- Lambda expressions, are just an expressions.
- Statements are not allowed inside the lambda functions (or expressions).
- Lambda functions are used in combinations with functions like : filter(), map() and reduce().
Code in this tutorial is tested on python 2.6 and python 3.2. Only difference is of reduce() function which was removed in python 3.x release, otherwise rest of the code in the tutorial works just fine.
lambda argument_list: expression
The argument list is comma separated value and the expression list consist of arithmetic expression using these argument lists. You can then assign this function to a variable and then use this variable for further manipulation or output.
Let’s take a look at example, here x is the argument and it is squared in this lamda function. The value of lambda function is then returned to the square_var.
squar_var=lambda x:x**2 print(square_var(8))
The above code is tested on python 3.2 (linux). In case of older version you can make appropriate changes in the print statement. As per the new change in python 3 we’re using print() instead of print “”.
Now let’s take a look at the three functions.
This function takes two arguments. The first argument in the function is the name of function and the second is the sequence or the list.
Syntax: map(func, seq)
Let’s take a look at map() function with example of a list.
a=[1,2,3,4] b=[2,3,4,5] c=map(lambda x,y:x+y, a,b) print(list(c))
Output: [3, 6, 9, 12]
Note: If you don’t print it as a list(c) then chances are there that output will be printed as a map object. So you have to print it as a list.
Like the above example you can also evaluate some more mathematical expressions and check the list as a boolean output. For example, make a list with number divisible and non-divisible by 2. Now add that condition in the lambda function expression and then get the output as a list. You’ll find that it prints true and false output.
Like map() function this filter() function also takes two arguments – func and list. Let’s take an example to see how the filter() function works.
b=[2,3,4,9] c=filter(lambda x:x%3==0,b) print(list(c))
You see filter() function removes the list items that are not divisible by 3. It only displays the two items that qualifies for the same. So the list argument in the filter function only returns value that are true as per the condition.
Reduce function is not available in python 3.x. You can skip this section if you’re using the new version of python. In case if you wish to use this function, you can use functools.reduce() instead. Reduce() function takes two arguments and the seq/list item continually evaluates until the last item. This way the list/sequence is reduced as per the arithmetical expression condition.
Let’s take a look at example to see how it works.
a=[1,2,3,4] reduce(lambda x,y:x>y, a) Output: false
This sums up our small tutorial on python lambda functions. You can keep tab on python 3.x version updates to see changes to the lambda functions. Hope this information helps. Feel free to let me know your views in the comments. You can also send me tweet @maheshkale, if you have any queries or feedback. |
This summary exercise involves crystal system and point group identification and stereo diagram construction.
This exercise is designed for a mid/upper-level undergraduate geology course on the principles of mineralogy.
Skills and concepts that students must have mastered
Students should have knowledge of basic chemistry and of minerals equivalent to what they would learn in an introductory geology class.
How the activity is situated in the course
This activity is the 29th of 36 mineralogy exercises and is used towards the end of the course.
Content/concepts goals for this activity
- Be able to identify symmetry.
- Become familiar with the crystal systems and the 32 point groups and be able to assign crystals to the correct ones.
- Be able to construct stereo diagrams for crystals of different shapes.
Higher order thinking skills goals for this activity
- Describe real objects (crystals) with abstract concepts such as symmetry and stereo diagrams.
Other skills goals for this activity
Description of the activity/assignment
This summary exercise involves crystal system and point group identification and stereo diagram construction. Students are presented with 5 blocks and for each block they must determine it's point group and crystal system, make stereo diagrams showing all symmetry and faces, and draw the blocks by hand or with SHAPE and label the Miller Indices. |
Start out with the following simple question:
Imagine you have tied a rope tightly around the full span of earth's equator (assume "earth" as being a perfect sphere and that the rope cannot be stretched). Now imagine that you add 1 meter to the initial rope length so that it becomes loose around the equator. Question: if you spread the rope at an even height from earth's surface (i.e. rope has a circular form, cocentric with earth's center) can you pass a cat underneath it?
Intuition says "no way", but let's examine the problem closely. Cutting a 2D slice at the equator, initially we have a circle with a perimeter equal to earth's perimeter at the equator (call it's radius "R") and a circle of rope tied tightly around it. When we loosen the perimeter by a meter (add a meter of rope) we are (indirectly) increasing it's radius. What we need to find out is how much the circle's radius will expand. (again intuition says it'll be very little due to the earth's dimensions and the fact that we are adding so little rope).
So, initially we have, from basic geometry:
(where P is the initial perimeter). When we add a meter of rope we are making P'=P+1 (where P' is the perimeter after the meter of rope was added). We also know (same as equation (1)) that:
Solving for R':
note the beauty of equation (2). It tells us that the increase in the radius is independant of it's initial radius. Simply, it doesn't matter whether we are tying a rope around an orange or the earth, when we add 1 meter to it's length (perimeter) , we ALWAYS increase it's radius by 16 centimeters.
let's just say I was marvelled by this simple result.
by the way... most cats can squeeze beneath 16 centimeters. |
From Uncyclopedia, the content-free encyclopedia
The Periodic Table of Elements (also called the "Sometimes Table" or "Occasional Table") can refer to any piece of furniture containing all 118 elements as long as it is periodically a table. Since 118 is such a large number, many scientists and other individuals pride themselves in memorizing every element in a periodic table, though few people find this impressive at all.
Memorizing the periodic table
One method of memorizing the periodic table involves first taking all the elements' atomic symbols and arranging them in order based on atomic number. Next, simply create a mnemonic with each word containing an atomic symbol (For example, hydrogen's atomic symbol is H, so the first word in the mnemonic could be Harold). A classic example of this method containing all 118 elements is provided below:
Beryllium, Boron, Carbon, Nitrogen, Oxygen, Fluorine, Neon, Sodium (Na), Magnesium, Aluminum, Silicon, Phosphorus, Sulfur, Chlorine, Argon, Potassium (K), Calcium, Scandium, Titanium, Vanadium, Chromium, Manganese, Iron (Fe), Cobalt, Nickel, Copper (Cu), Zinc, Gallium, Germanium, Arsenic, Selenium, Bromine, Krypton, Rubidium, Strontium, Yttrium, Zirconium, Niobium, Molybdenum, Technetium, Ruthenium, Rhodium, Palladium, Silver (Ag), Cadmium, Indium, Tin (Sn), Antimony (Sb), Tellurium, Iodine, Xenon, Cesium, Barium, Lanthanum, Cerium, Praseodymium, Neodymium, Promethium, Samarium, Europium, Gadolinium, Terbium, Dysprosium, Holmium, Erbium, Thulium, Ytterbium, Lutetium, Hafnium, Tantalum, Tungsten (W), Rhenium, Osmium, Iridium, Platinum, Gold (Au), Mercury (Hg), Thallium, Lead (Pb), Bismuth, Polonium, Astatine, Radon, Francium, Radium, Actinium, Thorium, Protactinium, Uranium, Neptunium, Plutonium, Americium, Curium, Berkelium, Californium, Einsteinium, Fermium, Mendelevium, Nobelium, Lawrencium, Rutherfordium, Dubnium, Seaborgium, Bohrium, Hassium, Meitnerium, Darmstadtium, Roentgenium, Copernicium, Ununtrium, 'Fl'erovium, Ununpentium, Livermorium, Ununseptium, and Ununoctium
Recite this phrase a few times, and you'll find yourself learning the periodic table in no time.
Songs. They're how we learn our ABCs (the alphabet song), our Do, Re, Mi's (Do, a deer), and the various mechanical parts included in modern buses and the unique onomatopoeic sounds produced by them (The Wheels on the Bus). Thus, Tom Leher decided to create a song about the elements to help people remember the periodic table. Just click on the video below and start singing along. The song's slow pace and easy to remember lyrics will have you spitting out the elements in no time. |
Is it hard for your kiddos to read large numbers? My kids have the hardest time, especially when I taught in fifth grade where they are reading nine digit numbers. Really all they need to read is three digits at a time. I tell the story of Place Value Lane where the mailman delivers mail to the places on Place Value Lane. I refer to each set of three digits as a "family living in a house" and each house has a different last name. There's the units house (they don't have a last name because they built their house before the others were there), the thousands house and the millions house etc. Each new family to Place Value Lane paints a bright red comma on their curb as a reminder of their last name so the postman will know where to deliver their letter. Hopefully, this helps the students see the numbers in sets of three digits instead of one long number that is difficult to read. When we write the number, we write it with houses over it to show where each family lives. Green over the thousands house and blue over the units house. We always circle the commas in bright red.
Then we pretend we are in a car driving down Place Value Lane. We stop in front of the first house and read who is inside the green thousands house and then write that three digit number in words. Then we pass the bright red comma. (I sometimes have students write the comma name thousand first, so they can see who is at home in the thousands house BEFORE the comma, and the units house AFTER the comma.)
After writing down the word thousand, we drive and stop at the blue units house and read the three digit number showing who is home.
It really helps to use when there are several zeros in a number. It places the long number in three digit "chunks" that are easier for the kids to work with.
I also use color coding when going from word form to standard form. The very first thing we look for is a "last name" comma word. If we have one, we draw a bright red rectangle around it. Then we look at the words before the word thousand. That is the three digit number in the green thousands house. Next, we look at the words after thousand. Those show the three digit number in the blue units house.
Here is an example of a students paper. Notice on the Standard to Expanded page, I had the kiddos draw the numbers pictorially using base ten drawings. This helps them understand the value of each digit, and why each digit is written as it is in expanded form. After practicing this using colored pencils, kids can go to using pencils only, but I always see someone using the green, red, blue pencils to color code their independent practice.
Also, check out my Reading Large Numbers on Place Value Lane in TpT. It is a hands on activity where students can create their own (up to 12 digit) numbers, and take a car and drive through the number to say the number in word form.
Hope you find this helpful. I'd love to hear your ideas on how you make reading large numbers easier for your students. |
On the subject of yesterday’s lesson, power, I thought I would briefly talk about one of the world’s most extravagant demonstrations of electrical power, the Z-Machine at Sandia National Laboratories. For those who have never heard of it, the Z-Machine is basically a very large energy storage device and it is used to produce extremely hot plasma, focused onto a very tiny area, in an attempt to create a nuclear fusion reaction. This machine is capable of firing pulses of energy close to 290 terawatts. That’s 290,000,000,000,000 watts! That's 80 times the world's electrical power! But you may be asking yourself, how this is possible?
The answer comes down to the unit time in which the energy is discharged, and that time is equal to about 100 nano seconds. To give you an idea of how short of a time frame that is, 100 seconds is to 100 nano seconds as the diameter of the earth is to the width of a human hair.
The interesting thing about this is how much energy is actually consumed during this event.
If you remember from yesterday’s lesson, power is equal to a change in energy per change in time (dw/dt). Sparing everyone the mess of a derivation of the equation, the expended energy can be written as..
w = the work done in joules
p = the power in watts
Δt = the change in time
Now we have an expression for the energy consumed within a time frame, where Δt is the change in time. Now you simply fill in the blanks! Remember that the Z-Machine fires a 290,000,000,000,000 watt pulse in 100 nano seconds.
We get about 29 mega joules. It may not seem like it, but that's actually not very much energy considering the power discharged.
Well that was longer than intended. Hope you found that real world application interesting! Lesson two will be posted later this week. |
Hello 0x00'ers, I am back at writing hardware related articles! In this article, we will take important steps. We will first of all be looking at AC vs DC, since there seems to be a lot of confusion about it amongst you software peeps . After that, I will cover new concepts: the "amount" of electricity (charge), electrical resistance & Ohm's law, and finally electrical power. Let's get started!
Direct current, or DC for short, is the most basic version of electricity. We already covered it a little bit in part 1 of this series. DC has a polarity, positive and negative, and the electrons always go in the same direction, from - to +. The voltage doesn't change either, because the direction of current depends on the polarity of the voltage. Unlike Alternating Current (AC), DC is much more stable. And thus, it is used in TV's and computers, because the sensitive electronics inside it require a stable voltage.
The most common source of DC are batteries. Though it is also very common that AC is converted into DC. We will learn how to do that in a phone charger project. A perfect example of AC > DC conversion is your phone charger. It takes 230V (or 120 in North America) AC from the outlet, steps it down to a lower voltage, and then turns it into a stable DC supply for your phone battery to use.
Since DC is the most basic form of electricity, there is not much to it. Here are the key things you need to remember about DC:
- DC has a polarity, + and -
- DC only goes in one direction all the time
The voltage of a DC power source always stays the same (except for batteries when they are empty, of course.)
Here you can see DC in a graph:
And here you can view a simulation of DC I made using Java Circuit Simulator. There is one battery on the left acting as a DC source with a value of 12V, and a resistor of 100 ohm acting as a consumer. You can clearly see the current keeps going in the same direction, and that the voltage stays the same (12V).
"But I thought current went from - to +, why does it go to + to - in your simulation?!" Well, in the early beginnings we electrical engineers were not so smart and we thought current went from + to - initially. Only later did we discover it was actually the other way around. But there is one problem: every formula was built on the idea of + going to -! So what was decided is that we'd have 2 types of current: the real current from - to +, and to keep things simple without changing the entire world of EE, we introduced the classic idea of + to - as "conventional current", and it is what electrical engineers use to keep things simple. I'll also use conventional current all the time in my projects, just know that in reality it is the other way around.
Let's now move on to Alternating Current, or AC for short. It is this form of electricity that comes out of your outlet in your house. The main difference between AC and DC is that AC, unlike DC, has no permanent polarity. The current of AC changes direction at a certain frequency (hence why it is called "alternating current"). This frequency is expressed in Hertz, which means "cycles per second". In Europe, the frequency of the AC coming out of your outlet is 50 Hz (Hertz), in the US, it is 60 Hz. What this means is that if you live in Europe, the polarity of your outlet changes 100 times per second, and in the US, it changes 120 times per second.
To understand this more, let's look at a graph of how 230V AC at 50 Hz looks like, the default standard in Europe.
Remember how 1.5V DC (the voltage of an AA battery) looked like in a graph. The horizontal line once again represents the time, in miliseconds (ms) in this case, and the vertical line represents the voltage. To better understand how AC works, we can view it in steps:
1.) The voltage starts at 0V, and climbs up to 325V in 5 ms. You may be thinking: "But I thought that in the EU the voltage of an outlet was 230V, not 325V!". Technically, this is correct. The effective voltage (which can be compared to "average voltage"), is 230V, but it's peak is 325V. We call this peak the "amplitude". More on amplitude later.
2.) The voltage goes from it's peak voltage of 325V back to 0V, again in 5ms. Because the voltage went to a positive voltage (325V) and back to 0V, we call this part of the cycle the positive alternation, because the voltage is positive (pretty obvious, not?)
3.) Now, the voltage goes negative. To -325V. Then it goes back to 0V. This part of the cycle is known as the negative alternation, because the voltage is negative in this alternation (again, pretty obvious). In the negative alternation, the current goes the other way as it went in the positive alternation. The current goes "backwards".
4.) Now, we are back at step 1. We just completed a cycle. The amount of cycles per second is expressed in hertz or Hz for short.
Here I made a simulation of an AC circuit. The AC source on the left (the circle with the sine-wave in it) generates an effective voltage of 230V with an amplitude of 325V, and at a frequency (cycles per second) of 50Hz. Again, the standard in Europe. Here you can see how AC works: first, we read a positive voltage that increases and then again decreases. Then we get a negative voltage that decreases all the way to it's negative amplitude, and then again rises to 0V and so on... You can also see that when the voltage goes from positive to negative and vice versa, the current also changes directions. Here are a few key things to memorize about AC:
- Has a changing polarity and voltage.
- Has a frequency.
- The direction in which the electrons flow changes.
- Unlike DC, AC can only be generated using kinetic energy.
The voltage can be changed using transformers, unlike DC.
- AC can not be stored, unlike DC (batteries).
There is much more to AC, but I will keep it at the basics for now. You now understand what AC is essentially, and that is enough for now. I just want you all to know that AC not only powers our homes, but that is also the thing that allows wireless communications! I will cover how that works in a later article.
Yes, AC literally drives the world!
Ever wondered what it would be called if you would put all the electrons that flowed through a wire for a certain time in one glass? Well, that is called electric charge! Electric charge is essentially the amount of electrons that flow in a specific time. The unit for electric charge is "Coulomb (C)", and it's symbol in formula's is "Q". From the description I gave, we can say that this formula is true:
Q = I * t
Q is the electric charge in Coulomb, or A.s/A.h (1C = 1A.s, 1A.h = 3600 A.s/C).
I is the electrical current, measured in Ampere as always.
t is the time that the current flows. Note: it is NOT a capital "T"! a capital "T" means temperature and is not needed in this formula). The time is expressed in seconds.
We can also draw other formulas from here now:
I = Q / t
t = Q/I
So, where does this come in practically? You will mostly find this in batteries, but it is not limited to that. For example, I have a phone that has a battery with a charge of 2700mAh (2.7Ah or ). Now we know that this battery can deliver 2.7A for an entire hour straight! (Remember that A.h stands for "Ampere-hour", which means that it can deliver X amount of amperes in a hour). Now, since we are hardware hackers, we open up the phone and utilize the battery for our own projects, and it will draw 4A maximum. So how do we know how long the battery will last without recharging? We apply our formula of course!
t = Q / I
If you did the maths, you'll see that the battery will last 2430 seconds or 40,5 minutes when we draw a current of 4A
Write down these formulas because they're very important!
Alright, we've reached the most important part of this entire series: Ohm's law. Ohm's law is the ABC of electricity, so it is VERY important for us to know! Let's begin:
We've already seen what voltage, current, and resistance is. But until now, we've seen them as 3 independant units. The thing is, there is a relation between voltage, current and resistance. This relation is known as "Ohm's law". Ohm's law says:
If voltage increases, so does current. If resistance increases, however, the amount of current drops.
To better help you understand this, I'll give you an example of a cyclist climbing a mountain. The speed of the cyclist is the current, the force he puts on his pedals is the voltage, and the pitch of the mountain he is climbing is the resistance. If the cyclist wants to mantain the same speed when the pitch increases, he will need to increase the force he puts on his pedals, or else he will slow down. When the cyclist wants to maintain the same speed when the pitch decreases, he will need to decrease the force he puts on his pedals, or he will go faster.
The same can be applied to electricity: say that we want to increase the amount of current in our circuit, we have 2 options: either we lower the resistance, or we increase the voltage. If we want to decrease the amount of current, we either need to decrease the amount of voltage, or increase the resistance. Here is a picture that you can use to better understand Ohm's law if you still don't get the concept:
As you can see, voltage is the force that pushes the electrons forward (or pulls them, in case of negative voltage), and the resistance is the thing that is slowing down the flow of electrons.
Using Ohm's Law
Alright, let's now see how we can calculate voltage, current, and resistance in a circuit! The basic formula for Ohm's law is:
U = I*R
Which means: voltage (U) equals current (I) multiplied by resistance (R). Let's calculate the amount of voltage needed for 1 ampere to flow in a circuit with a resistance of 1 ohm:
U = 1A * 1ohm = 1V.
Let's now apply this formula to something more practical.
Q: a lamp with an internal resistance of 766 ohm draws 0.3A. What is the voltage applied to this lamp?
A: U = I*R = 0.3A * 766ohm = 229,8V. When we round that up, we get 230V, the voltage used in residential homes in Europe.
There are other formulas too. You can also calculate resistance using this formula:
R = U/I.
Or current, using this formula:
I = U/R
You can remember all these formulas using the, what I call, "URIne pyramid" (a little bit innapropriate, but effective!).
Take not that "V" is the same as "U" in this picture: both stand for voltage.
You all most certainly heard the term "Watt" once in your life. But what is it? Watt is the unit that is used to express electric power. The symbol for electric power is "P", and the unit is Watt (W). So what is the formula for electric power? The formula for electric power is really simple:
P = U*I. Electric power equals voltage multiplied by current.
Let's again use a lamp, but this time one that draws 0.4A at 230V...
P = U*I = 230V * 0.4A = 92W.
The formula for electric power can also be used to calculate current:
I = P/U.
U = P/I.
Combining Ohm's Law and Electric Power
Ohm's law and electric power can be combined to perform advanced calculations. Here is an example:
Q: A lamp of 102W uses 120V. Calculate the resistance of the lamp.
Alright, there are 2 things we already know:
P = 102W.
U = 120V.
And to get the resistance of the lamp, we would apply Ohm's law like this:
R = U/I.
But there is a problem... We do not know the current! Therefore, we must first calculate the current from the 2 parts of the electric power formula we can already use: wattage and voltage.
I = P/U = 102W/120V = 0.85A.
And now, we can apply Ohm's law:
R = U/I = 120V/0.85A = 141 ohm.
Now of course, all formulas can be combined they have at least one parameter in common. You'll experience that yourself later.
Alright guys, I hope you all enjoyed the read! In my next article on the basics, we will cover electromagnetism & electromagnetic induction (he thing that makes wireless possible), and the article after that we'll discuss some common components.
Don't forget to give feedback in the comments!
Stay snappy, hardware hackers! |
The researchers say that the electrode, which is based on a framework of ordered carbon rods and fibres, behaves like a 'mini electrochemical reaction chamber.'
Lithium-sulfur batteries can potentially have capacities five times higher than the lithium-ion batteries presently used in consumer electronics. Like lithium-ion batteries, they use the flow of lithium ions in an electrolyte between two electrodes, an anode and a cathode. When the battery is powering a circuit, positive lithium ions generate a current by flowing from within the anode, through the electrolyte and into the cathode. Conversely, when the batteries are being charged, the polarity of the electrodes switches, and the lithium ions are forced to flow back into the anode, ready for another discharge cycle.
A schematic diagram of the sulfur (yellow) confined in the interconnected pore structure of mesoporous carbon, formed from carbon tubes propped apart by carbon nanofibres. (Image: Nature Materials)
Lithium-sulfur batteries differ from lithium-ion batteries in the way they store the ions. In lithium-ion batteries the ions are squeezed between molecules in the electrodes, a process known as intercalation. In lithium-sulfur batteries, however, the ions are taken in by a simple redox reaction with sulfur. Unlike intercalation this reaction is not limited by the electrode structure, which is why in theory the batteries can have a higher capacity for the same volume.
Still, there are problems in realising the devices. Sulfur is both electrically and ionically insulating, so for the electrodes to work the sulfur must always be in close contact with a conductor. Moreover, 'polysulphide' ions, which are intermediates in the redox reaction, are so soluble they can leak out of the electrodes and into the electrolyte, thereby reducing the electrodes' active mass.
Linda Nazar and colleagues at the University of Waterloo say they have got around these problems with a cathode formed on a conductive carbon framework. They begin by separating a number of thick, porous carbon nanorods, 6-7nm in diameter, with several thin carbon microfibres. Then they fill the structure with molten sulfur, which shrinks upon solidifying to leave porous channels into which an electrolyte can eventually flow. In the final step they apply a polymer coating, which helps prevent polysulphide ions from escaping.
In tests on simple cells, the Waterloo group found their cathode could retain capacities of 1320mAhg-1 - nearly 80 per cent of the theoretical capacity, and some three times that of the electrodes used in lithium-ion batteries. 'The carbon framework not only acts as an electronic conduit to the active [sulfur] mass contained within, but also serves as a mini-electrochemical reaction chamber,' they say. 'This entrapment ensures a more complete redox process takes place.'
Vasant Kumar, a chemist at the University of Cambridge who specialises in lithium batteries, thinks the work by Nazar and colleagues 'adds a new dimension' in increasing sulfur utilisation within a micro-structured cathode. However, he says there are still open questions, such as whether the assembly can be reproduced readily or whether there will be variations from one assembly to another. 'The authors have presented a plausible model, but need more evidence to be convincing,' he adds. 'Nevertheless the results are interesting and one of the highest reported capacities is given over many cycles.' |
Most of the surviving verse was set to music and were effectively ballads. Because Latin held such a sway over the educated classes this is the language most commonly used for the poems.
Following on from the medieval ages we get the Renaissance period and it is useful to consider what that brought into play as a direct comparison to what went before:
1. A growth in the use of the vernacular or the language of the common people.
2. Epic stories set in the local area dealing with legend and history and designed to create a national identity.
3. A freedom from the strictures of Latin allowed new techniques and structures to develop. This was particularly strong for German poetry as that language was less influenced by the sway of the Latin language.
It is worth mentioning "Chanson de geste". These epic poems appeared at the dawn of French literature and espoused heroic deeds. They spoke of Charles Martel, Charlemagne and Louis the Pious with a strong emphasis on the battles against the Moors and the Saracens.
Over time the historical and military matters declined to be replaced by more fantastic stories with monsters, giants and magic. |
Meteorite impacts have changed the surface of Mars over billions of years. The energy transferred into the ground by impacts fractured the outer shell (crust) of Mars, such that subsurface material was partly excavated, and surface material was buried elsewhere. The debris ejected by an impact forms specific deposits falling back to the surface. The characteristics of these deposits, so-called ejecta blankets, depend on the crater size, the nature of the ground, and the presence of an atmosphere. Consequently, from the analysis of different impact ejecta, scientists can learn something about the subsurface properties of Mars.
Many Martian impact craters show lobate or multilobed ejecta patterns with distal ridges (ramparts) that are attributed to the presence of water or ice in the subsurface. The 32-kilometer-diameter crater in the center of the images belongs to a class of impact craters with multiple layer ejecta deposits. Up to three layers of sinuous ejecta lobes can be recognized radially to the crater, some of them terminate in ramparts. These multiple layer ejecta deposits were emplaced by flow processes during crater formation, and might have resulted from a combination of impact into the water-rich ground, and interaction of the ejected material with the Martian atmosphere.
The impact crater with the striking ejecta blanket is located north of the Hellas impact basin, in an area that is suspected to be the former drainage basin of a lake that could have existed within Hellas on early Mars. Thus, at the time of impact one can assume groundwater was present near the surface, leading to the special “fluidized” appearance of the ejecta deposits and to the formation of small valleys flowing to the south (left in images), features that can still be observed today.
Image processing and the HRSC experiment on Mars Express
The images were acquired by the HRSC (High Resolution Stereo Camera) on 3 May 2017 during Mars Express Orbit 16890. The ground resolution is approximately 21 meters per pixel and the images are centered at 70° East and 22° South. The color image was created using data from the nadir channel, the field of view which is aligned perpendicular to the surface of Mars, and the color channels of the HRSC. The oblique perspective view was generated using data from the HRSC stereo channels. The anaglyph, which provides a three-dimensional view of the landscape when viewed using red-green or red-blue glasses, was derived from data acquired by the nadir channel and one stereo channel. The color-coded topographic view is based on a digital terrain model (DTM) of the region, from which the topography of the landscape can be derived. The reference body for the HRSC-DTM is a Mars equipotential surface (Areoid).
To download released raw images and DTMs of the region in GIS-ready formats, follow this link to the mapserver. For an overview of all press releases since 2004 click here.
Images: ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO
Where expressly stated, images are licenced under the Creative Commons Attribution-ShareAlike 3.0 IGO (CC BY-SA 3.0 IGO) licence. The user is allowed to reproduce, distribute, adapt, translate and publicly perform it, without explicit permission, provided that the content is accompanied by an acknowledgement that the source is credited as 'ESA/DLR/FU Berlin', a direct link to the licence text is provided and that it is clearly indicated if changes were made to the original content. Adaptation/translation/derivatives must be distributed under the same licence terms as this publication.
The High Resolution Stereo Camera was developed at the German Aerospace Center (DLR) and built in collaboration with partners in industry (EADS Astrium, Lewicki Microelectronic GmbH and Jena-Optronik GmbH). The science team, which is headed by Principal Investigator (PI) Ralf Jaumann, consists of 52 co-investigators from 34 institutions and 11 countries. The camera is operated by the DLR Institute of Planetary Research in Berlin-Adlershof. |
1 concern with the distinction between good and evil or right and wrong; right or good conduct [ant: immorality]
- The ability to distinguish good and evil or right and wrong, right or good conduct.
- In the context of "ethics": Motivation based on ideas of right and wrong.
The ability to distinguish good and evil or right and wrong, right or good conduct.
- Portuguese: moralidade
(ethics) Motivation based on ideas of right and wrong.
- Albanian: moralitet
- Arabic: الأخلاقية
- Azerbaijani: əxlaq
- Bulgarian: етика (etika)
- Chinese: 道德
- Croatian: etika
- Czech: morálnost
- Dutch: ethiek
- Esperanto: moraleco
- Estonian: kõlblus
- Finnish: etiikka
- French: moralité
- Georgian: ა(morali)
- German: Moral
- Greek: ηθική (ethiké)
- Hebrew: מוסר
- Hungarian: erkölcs
- Indonesian: kesusilaan
- Italian: moralità
- Japanese: 道徳 (dōtoku)
- Korean: 도덕 (dodŏg)
- Latvian: morāle
- Lithuanian: dorovė
- Persian: سيرت
- Polish: moralność
- Romanian: morală
- Russian: этика (etika)
- Serbian: етика (etika)
- Slovak: morálka
- Spanish: moralidad
- Swedish: moral
- Turkish: ahlâk
- Uyghur: exlaqsizliq
- Welsh: moes
- Yiddish: moral
Morality (from the Latin "manner, character, proper behavior") is the learning process of distinguishing between virtues and vices.
The proper system of values and principles of moral conduct promotes good customs (virtues), but also condemns bad customs (vices). Moral judgment determines whether an action should be considered as appropriate or inappropriate, selfish or unselfish. The true identification of morality is virtue, which has to be regarded as; goodness, propriety, rectitude, righteousness. Hypocrisy is the act of false virtue, by claiming to have higher moral standards which in reality do not correspond to the achievements.
Morals are evaluated through logic, experience and proper judgment, whether this originates from culture, philosophy, religion, society or individual conscience. In the normative and universal sense, morality refers to an ideal code of conduct, one which would be espoused in preference to alternatives by all rational people, under specified conditions. To deny 'morality' in this sense is a position known as moral skepticism.
Morality is sometimes used as a synonym for ethics, the systematic philosophical study of the moral domain. Ethics seeks to address questions such as how a moral outcome can be achieved in a specific situation (applied ethics), how moral values should be determined (normative ethics), what morals people actually abide by (descriptive ethics), what the fundamental nature of ethics or morality is, including whether it has any objective justification (meta-ethics), and how moral capacity or moral agency develops and what its nature is (moral psychology). In applied ethics, for example, the prohibition against taking human life is controversial with respect to capital punishment, abortion and wars of invasion. In normative ethics, a typical question might be whether a lie told for the sake of protecting someone from harm is justified. In meta-ethics, a key issue is the meaning of the terms "right" or "wrong". Moral realism would hold that there are true moral statements which report objective moral facts, whereas moral anti-realism would hold that morality is derived from any one of the norms prevalent in society (cultural relativism); the edicts of a god (divine command theory); is merely an expression of the speakers' sentiments (emotivism); an implied imperative (prescriptive); falsely presupposes that there are objective moral facts (error theory). Some thinkers hold that there is no correct definition of right behavior, that morality can only be judged with respect to particular situations, within the standards of particular belief systems and socio-historical contexts. This position, known as moral relativism, often cites empirical evidence from anthropology as evidence to support its claims. The opposite view, that there are universal, eternal moral truths is known as moral absolutism. Moral absolutists might concede that forces of social conformity significantly shape moral decisions, but deny that cultural norms and customs define morally right behavior.
Religion as a source of moral authorityReligious belief systems usually include the idea of divine will and divine judgment and usually correspond to a moral code of conduct.
Tribal and territorial moralities
Celia Green has made a distinction between tribal and territorial morality. She characterizes the latter as predominantly negative and proscriptive: it defines a person’s territory, including his or her property and dependants, which is not to be damaged or interfered with. Apart from these proscriptions, territorial morality is permissive, allowing the individual whatever behaviour does not interfere with the territory of another. By contrast, tribal morality is prescriptive, imposing the norms of the collective on the individual. These norms will be arbitrary, culturally dependent and ‘flexible’, whereas territorial morality aims at rules which are universal and absolute, such as Kant’s ‘categorical imperative’. Green relates the development of territorial morality to the rise of the concept of private property, and the ascendancy of contract over status.
In-group and out-groupSome observers hold that individuals have distinct sets of moral rules that they apply to different groups of people. There is the "ingroup," which includes the individual and those they believe to be of the same culture or race, and there is the "outgroup," whose members are not entitled to be treated according to the same rules. Some biologists, anthropologists and evolutionary psychologists believe this ingroup/outgroup difference is an evolutionary mechanism, one which evolved due to its enhanced survival aspects. Gary R. Johnson and V.S. Falger have argued that nationalism and patriotism are forms of this ingroup/outgroup boundary.
Fons Trompenaars, author of Did the Pedestrian Die?, tested members of different cultures with various moral dilemmas. One of these was whether the driver of a car would have his friend, a passenger riding in the car, lie in order to protect the driver from the consequences of driving too fast and hitting a pedestrian. Trompenaars found that different cultures had quite different expectations (from none to almost certain).
Evolutionary perspectivesEvolutionary biologists start from the assumption that morality is a product of evolutionary forces. On this view, moral codes are ultimately founded on emotional instincts and intuitions that were selected for in the past because they aided survival and reproduction (inclusive fitness). The strength of the maternal bond is one example. Another is the Westermarck effect, seen as underpinning taboos against incest, which decreases the likelihood of inbreeding depression.
The phenomenon of 'reciprocity' in nature is seen by evolutionary biologists as one way to begin to understand human morality. Its function is typically to ensure a reliable supply of essential resources, especially for animals living in a habitat where food quantity or quality fluctuates unpredictably. For example, on any given night for vampire bats, some individuals fail to feed on prey while others consume a surplus of blood. Bats that have successfully fed then regurgitate part of their blood meal to save a conspecific from starvation. Since these animals live in close-knit groups over many years, an individual can count on other group members to return the favor on nights when it goes hungry (Wilkinson, 1984)
It has been convincingly demonstrated that chimpanzees show empathy for each other in a wide variety of contexts. They also possess the ability to engage in deception, and a level of social 'politics' prototypical of our own tendencies for gossip, and reputation management.
Christopher Boehm (1982) has hypothesized that the incremental development of moral complexity throughout hominid evolution was due to the increasing need to avoid disputes and injuries in moving to open savanna and developing stone weapons. Other theories are that increasing complexity was simply a correlate of increasing group size and brain size, and in particular the development of theory of mind abilities. Richard Dawkins in The God Delusion suggested that our morality is a result of our biological evolutionary history and that the Moral Zeitgeist helps describe how morality evolves from biological and cultural origins and evolves with time within a culture.
Neuroscientific and psychiatric perspectives
Research on mirror neurons, since their discovery in 1996, suggests that they may have a strong role to play in empathy. Social neuro-scientist Jean Decety thinks that the ability to recognize and vicariously experience what another creature is undergoing was a key step forward in the evolution of social behavior, and ultimately, morality. The inability to feel empathy is one of the defining characteristic of psychopathy, and this would appear to lend support to Decety's view.
Morality as maladaptive and universal
Phil Roberts, Jr. has offered a perspective in which morality, and specifically the capacity for guilt, is viewed as a maladaptive byproduct of the evolution of rationality:
Guilt is a maladaptive manifestation of our need to justify our existence, in this case by conforming to a shared subconscious theory of rationality in which 'being rational' is simply a matter of 'being objective', as exemplified in the moral maxim, 'Love (intrinsically value) your neighbor as you love (intrinsically value) yourself'. Although none of us can actually measure up to this standard, we nonetheless come to experience feelings of worthlessness (guilt) along with a corresponding reduction in the will to survive (depression) when we deviate from the standard to an unreasonable degree. In other words, a capacity for guilt (having a conscience) is a part of the price we humans have had to pay for having become a little too objective (too rational) for our own good.http://www.rationology.net
Morality in judicial systems
In most systems, the lack of morality of the individual can also be a sufficient cause for punishment, or can be an element for the grading of the punishment.
Especially in the systems where modesty (i.e., with reference to sexual crimes) is legally protected or otherwise regulated, the definition of morality as a legal element and in order to determine the cases of infringement, is usually left to the vision and appreciation of the single judge and hardly ever precisely specified. In such cases, it is common to verify an application of the prevalent common morality of the interested community, that consequently becomes enforced by the law for further reference.
The government of South Africa is attempting to create a Moral Regeneration movement. Part of this is a proposed Bill of Morals, which will bring a biblical-based "moral code" into the realm of law. This move by a nominally secular democracy has attracted relatively little criticism.
Morality and politics
If morality is the answer to the question 'how ought we to live' at the individual level, politics can be seen as addressing the same question at the social level. It is therefore unsurprising that evidence has been found of a relationship between attitudes in morality and politics. Jonathan Haidt and Jesse Graham have studied the differences between liberals and conservatives, in this regard. According to their model, political conservatives make their moral choices using five moral variables (harm/care, fairness/reciprocity, ingroup loyalty, authority/respect, purity/sanctity), whereas liberals use only two (harm/care and fairness/reciprocity). Haidt also hypothesizes that the origin of this division in the United States can be traced to geohistorical factors, with conservatism strongest in closely knit, ethnically homogenous communities, in contrast to port-cities, where the cultural mix is greater, thus requiring more liberalism.
Group morality develops from shared concepts and beliefs and is often codified to regulate behavior within a culture or community. Various defined actions come to be called moral or immoral. Individuals who choose moral action are popularly held to possess "moral fiber", whereas those who indulge in immoral behavior may be labeled as socially degenerate. The continued existence of a group may depend on widespread conformity to codes of morality; an inability to adjust moral codes in response to new challenges is sometimes credited with the demise of a community (a positive example would be the function of Cistercian reform in reviving monasticism; a negative example would be the role of the Dowager Empress in the subjugation of China to European interests). Within nationalist movements, there has been some tendency to feel that a nation will not survive or prosper without acknowledging one common morality, regardless of in what it consists. Political Morality is also relevant to the behaviour internationally of national governments, and to the support they receive from their host population. Noam Chomsky states that
Codified morality is generally distinguished from custom, another way for a community to define appropriate activity, by the former's derivation from natural or universal principles. In certain religious communities, the Divine is said to provide these principles through revelation, sometimes in great detail. Such codes may be called laws, as in the Law of Moses, or community morality may be defined through commentary on the texts of revelation, as in Islamic law. Such codes are distinguished from legal or judicial right, including civil rights, which are based on the accumulated traditions, decrees and legislation of a political authority, though these latter often invoke the authority of the moral law.
Morality can also be seen as the collection of beliefs as to what constitutes a good life. Since throughout most of human history, religions have provided both visions and regulations for an ideal life, morality is often confused with religious precepts. In secular communities, lifestyle choices, which represent an individual's conception of the good life, are often discussed in terms of "morality". Individuals sometimes feel that making an appropriate lifestyle choice invokes a true morality, and that accepted codes of conduct within their chosen community are fundamentally moral, even when such codes deviate from more general social principles.
Moral codes are often complex definitions of right and wrong that are based upon well-defined value systems. Although some people might think that a moral code is simple, rarely is there anything simple about one's values, ethics, etc. or, for that matter, the judgment of those of others. The difficulty lies in the fact that morals are often part of a religion and more often than not about culture codes. Sometimes, moral codes give way to legal codes, which couple penalties or corrective actions with particular practices. Note that while many legal codes are merely built on a foundation of religious and/or cultural moral codes, ofttimes they are one and the same.
Examples of moral codes include the Golden Rule; the Noble Eightfold Path of Buddhism; the ancient Egyptian code of Ma'at ;the ten commandments of Judaism, Christianity, and Islam; the yamas and niyama of the Hindu scriptures; the ten Indian commandments; and the principle of the Dessek.
Another related concept is the moral core which is assumed to be innate in each individual, to those who accept that differences between individuals are more important than posited Creators or their rules. This, in some religious systems and beliefs (e.g. Taoism, Moralism and Gnosticism), is assumed to be the basis of all aesthetics and thus moral choice. Moral codes as such are therefore seen as coercive — part of human politics.
Religiosity and morality
In the scientific literature, the degree of religiosity is generally found to be associated with higher ethical attitudes. Although a recent study by Gregory S. Paul published in the Journal of Religion and Society argues for a positive correlation between the degree of public religiosity in a society and certain measures of dysfunction, an analysis published later in the same journal contends that a number of methodological problems undermine any findings or conclusions to be taken from the research. In a response to the study by Paul, Gary F. Jensen builds on and refines Paul's study. His conclusion, after carrying out elaborate multivariate statistical studies, is that there is a correlation (and perhaps a causal relationship) of higher homicide rates, not with Christianity, but with dualism in Christianity, that is to say with the proportion of the population who believe the devil and hell exist. Excerpt: "A multiple regression analysis reveals a complex relationship with some dimensions of religiosity encouraging homicide and other dimensions discouraging it." Meanwhile, other studies seem to show positive links in the relationship between religiosity and moral behavior — for example, surveys suggesting a positive connection between faith and altruism. Modern research in criminology also acknowledges an inverse relationship between religion and crime, with many studies establishing this beneficial connection (though some claim it is a modest one). Indeed, a meta-analysis of 60 studies on religion and crime concluded, “religious behaviors and beliefs exert a moderate deterrent effect on individuals’ criminal behavior”.
- Secular ethics
- Moral relativism
- Moral absolutism
- Moral universalism
- Deontological ethics
- Ethical dilemma
- Applied ethics
- Moral particularism
- Criticism of atheism
- Criticism of religion
- Kohlberg's stages of moral development
- Public morality
- The ends justify the means
- Moral Zeitgeist
- Fairness Judgments: Genuine Morality or Disguised Egoism? Psychological Article on Fairness (registration required)
- The Stanford Encyclopedia of Philosophy on the Definition of Morality
- Objective Morality An evolutionary approach
- Christian and Muslim debates on Morality
- Morality and Judaism chabad.org
- Wiki site for discussing and taking action on shared morals (WorldMoralMovement.org)
- Morals and Ethics in Islam
- Understanding the Islam, Christianity Debate
- How Sex Was Made A Sin
- Stephen Pinker on the Psychology and Evolutionary Biology of Morality
morality in Bosnian: Moral
morality in Catalan: Moral
morality in Czech: Morálka
morality in German: Moral
morality in Estonian: Moraal
morality in Spanish: Moral
morality in Esperanto: Moralo
morality in French: Morale
morality in Croatian: Moral
morality in Indonesian: Moral
morality in Interlingua (International Auxiliary Language Association): Moral
morality in Icelandic: Siðferði
morality in Italian: Morale
morality in Hebrew: מוסר
morality in Latvian: Morāle
morality in Lithuanian: Moralė
morality in Macedonian: Морал
morality in Malay (macrolanguage): Moral
morality in Dutch: Moraal
morality in Japanese: 道徳
morality in Norwegian Nynorsk: Moral
morality in Polish: Moralność
morality in Portuguese: Moralidade
morality in Russian: Мораль
morality in Albanian: Morali
morality in Simple English: Morality
morality in Slovak: Morálka
morality in Serbian: Морал
morality in Serbo-Croatian: Moral
morality in Finnish: Moraali
morality in Swedish: Moral
morality in Thai: คุณธรรม
morality in Turkish: Ahlak
morality in Ukrainian: Мораль
morality in Yiddish: מוסר
morality in Chinese: 道德
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Many of us believe dinosaurs to be extinct but in truth, they surround us every day. All the world’s birds, from the pigeons of our cities to the gulls of our seasides, are descended from dinosaurs, and modern science now classifies the birds with their long-dead kin. The gulf between dinosaurs and modern birds may seem huge, but the discovery of several feathered dinosaurs are seriously blurring the line between the two. And now, new research on the feathered dinosaur Microraptor reveals that birds may have evolved from dinosaur ancestors that flew not on two wings, but on four.
The link between dinosaur and bird was cemented in the last two decades, when palaeontologists unearthed hundreds of beautifully preserved fossils in the Liaoning province of China. Many of the newcomers were small predators, belonging to the same group as the famous Velociraptor (and indeed, most scientists believe that this Hollywood star was also covered in primitive feathers).
The new species run the full evolutionary gamut from flightless dinosaurs to flying birds. They range from Sinosauropteryx with its primitive, downy, proto-feathers to Caudipteryx, a dinosaur with proper flight-capable feathers, to Confuciusornis, a true bird. Together, these species provide a tantalising snapshot of how small prehistoric predators transformed into the familiar fliers of today’s skies.
One of these species, Microraptor, stood out among the rest, for it had winged legs as well as arms. The animal’s metatarsal bones were covered in long, asymmetric flight feathers. Their shape is clearly designed to produce lift during flight, but how Microraptor used its four wings has puzzled scientists. The species’ discoverers believed that by splaying its legs out sideways from its body, it held its wings in tandem like a dragonfly. But for Sankar Chatterjee and R. Jack Templin of Texas Tech University, the facts didn’t add up.
For a start, no bird or dinosaur has shown the ability to splay its legs out sideways and doing so would probably have dislocated the hip. Microraptor must have tucked its legs vertically beneath its body, like modern birds of prey do when they pounce. Its leg flight feathers would only produce lift if the leading edge faced forward, against the flow of air. The leg feathers must therefore have protruded horizontally from the tucked legs. Chatterjee’s revised pose makes Microraptor look like a feathered biplane, with the leg wings sitting below and just behind the main pair.
This new posture may also answer a long-standing debate about the origin of flight. Some scientists believe that bird flight evolved when ground-dwelling dinosaurs began to take to the skies. In contrast to this ‘ground-up’ theory, the ‘trees-down’ camp believes that tree-dwelling dinosaurs evolved flight to glide from tree to tree.
And this is exactly what Microraptor did. It lacked the muscles for a ground take-off and couldn’t get a running start for fear of damaging its leg feathers. But a computer simulation showed that Microraptor could successfully fly between treetops, covering over forty metres in an undulating glide.
It is unclear if Microraptor could truly fly or was just an exceptional glider. Certainly, its body plan shows many features that would make its avian descendants such great aeronauts. It had a large sternum for attaching powerful flight muscles and strengthened ribs to withstand the heavy pressures of a flight stroke. Its long, feathered tail acted a stabiliser and rudder and its tibia (shin bone) was covered in smaller, backwards-facing feathers. Modern birds of prey carry similar feather ‘trousers’ and Chatterjee believes that they helped to reduce drag by breaking up turbulent airflow behind the animal’s leg.
It could be that Microraptor‘s biplane design was just a failed evolutionary experiment. But Chatterjee thinks otherwise. He believes that the biplane model was a stepping stone to the two-wing flight of modern birds. As the front pair of wings grew larger and produced more lift, they eventually took over the responsibilities formerly shared with the hind pair. This series of events stunningly mirrors the evolution of man-made aircraft. When the Wright brothers unveiled their new plane in 1903, little did they no that dinosaurs had got there first 125 million years ago.
Reference: S. Chatterjee, R. J. Templin (2007). Biplane wing planform and flight performance of the feathered dinosaur Microraptor gui Proceedings of the National Academy of Sciences, 104 (5), 1576-1580 DOI: 10.1073/pnas.0609975104 |
Whooping cough or pertussis, as it is called in medical parlance, is a contagious disease. Unlike some other diseases, a new born baby has no immunity to this disease, and can get it any time after birth. It commonly affects infants during the first year of their life, when it is very severe and most of the deaths due to it occur during this period. Many cases occur in children upto 5 years of age. In some cases children upto 12 years may also be affected. The disease may cause serious trouble in the lungs.
This highly infectious disease is caused by bacteria. It spreads rapidly from one child to another by droplet-infection. This is especially so during the early catarrhal stage, but once the typical spasmodic bout starts, the infectivity becomes negligible. This disease has a prolonged course of 8 to 10 weeks.
The disease has a catarrhal and a spasmodic stage. For the first week, the cough is like an ordinary upper respiratory catarrh. At the end of a week, it becomes spasmodic and comes in bouts, initially more often during the night, but later during the day as well. The child goes on coughing. His face becomes red and suffused, the tongue protrudes and the eyes begin to water. At the end of the bout, the child takes a deep breath, and there is a prolonged croaking sound which is called a whoop. This sound is produced by the air entering through a partially closed glottis (entrance to the larynx). This gives the disease its name. The child brings out a sticky secretion from his nose and mouth and very often vomits. At the end of the bout, the child lies back exhausted. Gradually, over the next three or four weeks, the bouts of cough and their duration become less and disappear in about 8 to 10 weeks from the beginning of the disease. In immunized children, the disease is mild and atypical.
Due to the severity of bouts of cough, bleeding can occur into the eyes, from the nose, the lung, and , in rare cases, into the brain, resulting in convulsions. In many young children, lung complications such as collapse of a part of the lung are common because of the thick sticky nature of the secretions blocking the passage of air to a part of the lung. Secondary infection may result in pneumonia. They may be convulsions, and, in rare cases, inflammation of the brain.
Whooping cough is caused by the micro-organisms Bordetella pertussis and Bordetella parapertussis. Of these, the first one gives the rise to more severe infections. Whooping cough is also associated with various adinoviruses, para-influenza and respiratory viruses. The actual cause of the disease, however, is wrong feeding of children with refined and deminralised foods and absence of a sufficient quantity of fresh fruits and salad vegetables in their dietary. This results in accumulation of excessive quantities of catarrh and mucus in the child’s system. The disease is an attempt on the part of the nature to throw out this catarrh and mucus. The use of drugs to treat other diseases can also lead to whooping cough.
In the beginning of the treatment, the child should be placed on a fast, on orange juice and water for few days. He should be given the juice of an orange diluted with warm water on 50:50 basis. He should not be given milk or anything else. He should be given warm water enema daily during this period to cleanse the bowels. In case of constipation, a mild laxative, preferably castor oil, should be administered. This will also relieve the pain in the abdominal muscles which are usually strained during the paroxysms of coughing. Cold packs should be applied to the throat and upper chest as required. Epsom-salt baths will be beneficial during this period.
After the more sever symptoms have cleared, the patient should be placed on an exclusive diet of fresh fruits for a few days. IN this regimen, we should take fresh juicy fruits such as apple, orange, pineapple and papaya. After further recovery, he can adopt a regular well-balanced diet, according to his age. The emphasis should be on fresh fruit, fruit and vegetable juices and milk. When the convalescent stage has been reached, the child should be encouraged to spend as much time as possible out of doors.
Certain home remedies have been found beneficial in the treatment of whooping cough. The most effective of these remedies is the use of garlic. The syrup of garlic should be given in the dosage of five drops to a tablespoon two or three times a day for treating this condition. It should be given more often if the coughing spells are frequent and violent.
Ginger ( adrak) is another effective remedy for whooping cough. A teaspoon of fresh ginger juice, mixed with a cup of fenugreek (methi) decoction and honey to taste, is an excellent diaphoretic. It acts as an expectorant in this disease.
A syrup prepared by mixing a teaspoon of fresh radish (muli) with equal quantity of honey and a little rock salt, is beneficial in the treatment of this disease. It should be given thrice daily.
Almond (badam) oil is valuable in whooping cough. It should be given missed with 10 drops each of fresh white onion juice and ginger juice, daily thrice for a fortnight. It will give relief. |
In this word blends worksheet, students identify the pictures that begin with the 'wh' sound. Students circle the 3 pictures and say the names for the pictures.
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Large "Wh" Words
Help young readers learn which way to pronounce the wh- digraph with this set of word cards. Introduce and sort through these 21 different words as a whole class before having students practice independently or in pairs as a language...
Pre-K - 2nd English Language Arts CCSS: Adaptable
Phonics Instructional Routine: Read and Write Words with Consonant Digraphs
Use consonant digraphs to introduce learners to word patterns and high frequency words. They observe a chart with the digraphs /sh/, /ch/, /th/, and /wh/. After listening to each of these phonemes, scholars watch as the teacher...
K - 1st English Language Arts
Digraph Word Sort Recording
Young readers sort their way through a deck of word cards in order to become familiar with four common spelling patterns. Focusing on the ch-, sh-, wh-, and th- consonant digraphs, students draw cards and write each word in the box...
K - 2nd English Language Arts CCSS: Adaptable
Digraph Word Hunt
Support young learners with developing their spelling skills and ready fluency with this simple graphic organizer. Focusing on the four consonant digraphs /th/, /ch/, /sh/, and /wh/, students dig through their independent reading books...
K - 3rd English Language Arts CCSS: Adaptable
Word Work: Blends, Digraphs & Trigraphs
Practice thirty-three different consonant blends, digraphs, and trigraphs with your emergent readers! Each letter combination has its own column in which you and your learners can write down five different words that demonstrate the...
K - 1st English Language Arts CCSS: Adaptable
High Frequency and Spelling Words
Four high frequency word activities are to be found on this set of simple worksheets. Each activity is to be completed on a different day and each focuses on the /qu/ and /wh/ spelling pattern. Learners will write sentences, circle words...
1st - 3rd English Language Arts |
Session 11: Using Text Features to Strengthen Writing
Nonfiction can be like a party for your eyes! Your eyes can dance across the page because there is so much to look at! When the page in a nonfiction book contains lots of text features, you not only stay super engaged, but you end up learning about the topic in lots of different ways. You tend to be more knowledgeable about a topic when you have learned about it through lots of channels: pictures, numbers, charts, maps, diagrams, text boxes- the works.
When writing an informational text, using text features can help to teach information and to make central ideas prominent.
Look at how the following sections from an informational text are set up.
Teaching and Active Engagement:
Today, in small groups, you are going to study mentor texts and list all different types of text features you find. Jot what the text feature looks like and what it does--how does this particular text feature teach information about the topic in a special way?
(Record what students found on chart paper p. 101)
Let's practice adding text features into a piece of writing.
We shouldn't just randomly pick a text feature to try and add. Let's look over this draft and see if there is additional related information we could teach in a new and special way, using a different form of a text feature.
- Add a photo or illustration of some of the destruction that is described in the beginning of the chapter- the reason that they begin with a description is for the reader to really picture this devastation in their mind
- Add a subtitle underneath image
- Add shocking statistics about girls who are denied an education and put it in the form of a text box-this will help highlight this information for the reader
Link:Take out your own drafts and plan a few text features to insert into your writing. Make sure you are thinking, "What text features might I use so that I can teach information in new and special ways? What could I add to my writing? What could I reformat?"
Turn and tell the person beside you what you are thinking and explain why you are picking that feature and where you might place it on the page.
Continue to plan text features for your chapters. You might want to add features on Post-its or on scrap pieces of paper that you tape on. Others might need to totally reformat a chapter.
Reference the chart Writing Information Texts Well
- Make your sentences more complex so you sound more authoritative
- Use text features purposefully, to teach information in new and special way
Let's end the class today by sharing our text features by taking a text-feature feedback walk. Not only are you going to study each other's work, but you're going to jot down some feedback that you'll share later. Each of you need to set up a praise and pointers text-feature exhibits and feedback sheet.
When giving feedback, make clear compliments on their praise sheets and concrete, helpful tips on their pointers sheet.
Continue to revise your draft for text features and cohesion, referring to the "Praise and Pointers' feedback sheets you collected from your gallery walk. You may have noticed amazing text features created by your classmates that gave you great ideas to incorporate into your own text features. It is fine to borrow ideas from each other. |
There are about a dozen types of epilepsy, and the type you have plays a role in which kind of seizure you may have.
There are two main types of seizures:
Focal seizures: These start in a particular part of your brain, and their names are based on the part where they happen. They can cause both physical and emotional effects and make you feel, see, or hear things that aren’t there. About 60% of people with epilepsy have this type of seizure, which is sometimes called a partial seizure. Sometimes, the symptoms of a focal seizure can be mistaken for signs of mental illness or another kind of nerve disorder.
Generalized seizures: These happen when nerve cells on both sides of your brain misfire. They can make you have muscle spasms, black out, or fall.
Seizures aren’t always an either-or thing: Some people have seizures that start as one kind, then become another. And it’s not easy to classify some of them: These are called unknown-onset seizures, and they can cause both sensory and physical symptoms.
There are six types:
Tonic-clonic (or grand mal) seizures: These are the most noticeable. When you have this type, your body stiffens, jerks, and shakes, and you lose consciousness. Sometimes you lose control of your bladder or bowels. They usually last 1 to 3 minutes -- if they go on longer, someone should call 911. That can lead to breathing problems or make you bite your tongue or cheek.
Clonic seizures: Your muscles have spasms, which often make your face, neck, and arm muscles jerk rhythmically. They may last several minutes.
Tonic seizures: The muscles in your arms, legs, or trunk tense up. These usually last less than 20 seconds and often happen when you’re asleep. But if you’re standing up at the time, you can lose your balance and fall. These are more common in people who have a type of epilepsy known as Lennox-Gastaut syndrome, though people with other types can have them, too.
Atonic seizures: Your muscles suddenly go limp, and your head may lean forward. If you’re holding something, you might drop it, and if you’re standing, you might fall. These usually last less than 15 seconds, but some people have several in a row. Because of the risk of falling, people who tend to have atonic seizures may need to wear something like a helmet to protect their heads.
People who have Lennox-Gastaut syndrome and another kind of epilepsy called Dravet syndrome are more likely to have this kind of seizure.
Myoclonic seizures: Your muscles suddenly jerk as if you’ve been shocked. They may start in the same part of the brain as an atonic seizure, and some people have both myoclonic and atonic seizures.
Absence (or petit mal) seizures: You seem disconnected from others around you and don’t respond to them. You may stare blankly into space, and your eyes might roll back in your head. They usually last only a few seconds, and you may not remember having one. They’re most common in children under 14.
Doctors break these into three groups:
Simple focal seizures: They change how your senses read the world around you: They can make you smell or taste something strange, and may make your fingers, arms, or legs twitch. You also might see flashes of light or feel dizzy. You’re not likely to lose consciousness, but you might feel sweaty or nauseated.
Complex focal seizures: These usually happen in the part of your brain that controls emotion and memory. You may lose consciousness but still look like you’re awake, or you may do things like gag, smack your lips, laugh, or cry. It may take several minutes for someone who’s having a complex focal seizure to come out of it.
Secondary generalized seizures: These start in one part of your brain and spread to the nerve cells on both sides. They can cause some of the same physical symptoms as a generalized seizure, like convulsions or muscle slackness. |
Cat-people! Think you know your feline friends? Think again and take a look at our 20 amazing cat facts…
Cats have two vocal cords
Dogs have a range of around ten sounds, but cats can make over a hundred different noises. This is because they have thick folds of membrane in their larynx, known as false vocal cords, which can vibrate to produce a greater variety of sounds.
Humans and cats have identical regions in their brains that are responsible for emotion. In fact, a cat’s brain is more similar to a human’s than it is to a dog’s brain.
Purring can influence emotion in humans
Karen McComb, a behavioural ecologist, discovered that cats alter their purr when they’re after something. Called the soliciting purr, the cat adds a cry to the sound, giving it a frequency of 380Hz, which is within the range of a human baby cry. Humans intrinsically react to this sound, so when they hear the purr, they naturally respond.
Cats aren’t colour blind as was previously thought, but they do have limited colour perception. It’s agreed they can see blue and green.
They mimic other animals, like snakes
A lot of animals mimic scarier ones if they feel threatened and some behaviour experts believe a cat’s hiss is meant to mimic a snake. It’s easy to see why; in addition to the actual hiss, a cat will push its ears down, bear its fangs, squint its eyes and spray saliva – making it look very snake-like.
Domestic cats are the only ones who walk with their tails straight up. Wild cats hold them horizontally or between their legs.
They use their whiskers like radar
A cat’s whiskers (vibrissae) do more than prevent it getting stuck in things. The whiskers are embedded in tons of nerves and blood vessels, making them work like kitty radar. Thanks to whiskers, a cat can navigate around objects in the dark and also judge distances.
A cat has around 250 bones, ten per cent of which are in the tail. This makes the tail such a good balancing aid.
An undercoat protects them from extreme temperatures
Able to stand high or low temperatures, even indoor cats will grow an undercoat that offers protection from hot or cold. This is why cats can be found happily sleeping next to a radiator oozing out intense heat all evening. Humans will feel uncomfortable when their skin temperature passes around 35 degrees Celsius (95 Fahrenheit), but a cat won’t notice anything up to around 52 degrees Celsius (126 Fahrenheit).
They can reach speeds of up to 48 kilometres (30 miles) per hour over a short distance.
They don’t need to drink to survive
You should always provide water for your cat, but they don’t actually drink much. Cats have evolved to get sufficient water from prey and, like camels, have various tricks for maximum water absorption. A wild cat’s prey is 70 to 75 per cent water, wet food for domestic cats has moisture content of around 80 per cent, but dried food is only around five to ten per cent.
Most cats go nuts for catnip, but about 30 per cent have no response because they don’t possess the necessary gene to make them perky.
A cat’s field of vision is 200 degrees
A human’s field of vision is 180 degrees, but a cat’s is around 200. They also have much better peripheral vision than humans, so even if they aren’t looking directly at an object, they can still track its movements. This is just perfect for keeping a sneaky eye on prey, or treats!
Grooming is important to a cat for maintaining fur, removing smells and cooling down. A cat spends about a third of its waking hours grooming itself.
Cats have scent glands in their paws
When a cat kneads at a surface, they transfer their scent and mark it as belonging to them. They actually have scent glands in the pads on their paws, so when they do this paddy-paw action on your lap, they are basically marking you as their territory.
Cats urine glows in the dark because it contains phosphorus. Ultraviolet light adds additional energy which makes the chemiluminescence easier to see
They can smell with their mouth
Cats have a special organ just behind their teeth, so when they sniff something good they can open their mouth to collect the smell.
Cats aren’t great at focusing on slow-moving objects and some behaviourists think this is why they wiggle before pouncing, as it helps them pinpoint prey.
Cats are asleep two thirds of their life
As cats spend around two thirds of their days asleep, a six-year-old cat will only have been awake for two years of its life!
Discover more amazing animal facts in the latest issue of World of Animals. It’s available from all good retailers, or you can order it online from the ImagineShop. If you have a tablet or smartphone, you can also download the digital version onto your iOS or Android device. To make sure you never miss an issue of World of Animals magazine, make sure you subscribe today! |
Even the best language arts teachers cannot impart more than 300-400 words to students in a school year through formal, explicit instruction, yet by the time students reach 8th grade, they should know about 25,000 words! That means that most words and their meanings that students absorb come from informal, daily interactions with language. Research indicates that reading widely (about many topics and in many genres) and deeply (thoughtfully and reflectively) is one of the best ways for children to learn vocabulary incidentally.
A recent article in The Reading Teacher, by Bridget Dalton and Dana L. Grisham, provides suggestions for ways these research-based principles can be married to newly available technology to enhance students’ vocabulary acquisition. We were interested to learn that Dr. Dalton had previously served as Chief Officer of Literacy and Technology for CAST, a non-profit research and development organization that focuses on universal design for learning theory and practice. Dr. Yellin is a member of the Board of Directors of CAST. Some of the favorite technological tools mentioned by the authors are: |
The mass of water vapor in a given volume of air (i.e., density of water vapor in a given parcel, usually expressed in grams per cubic meter.
Having a pH value less than 7.
Activated Oxygen is the linking of 3 oxygen molecules otherwise known as O3, or ozone. When the oxygen (O2) around us rises to the upper atmosphere and is exposed to the sun’s ultraviolet rays, that oxygen is naturally turned into ozone (O3). This “ozone layer” protects us from the sun’s harmful UV rays. Since ozone is heavier than air, it naturally falls back to earth. This is the ozone that naturally purifies our air and water. Without ozone nature could not purify the Earth.
Actual Vapor Pressure
The partial pressure exerted by the water vapor present in a parcel. Water in a gaseous state (i.e. water vapor) exerts a pressure just like the atmospheric air. Vapor pressure is also measured in millibars.
Association of Home Appliance Manufacturers.
Water produced from an atmospheric water generator (AWG).
Having a pH value greater than 7.
American National Standards Institute. |
Length: 8.5 - 9.5 mm
The Phymata species are the most commonly encountered Ambush Bugs in eastern North America. Two species are most commonly encountered in the region, Phymata pennsylvanica (shown here) and Phymata americana. The latter differs by having a continuously smooth margin of the connexivum, while P. pennsylvanica has a prominent notch on the fourth segment as seen in the photo at left.
Phymata Ambush Bugs are sit-and-wait predators that are well camouflaged on flower heads. When an insect comes within reach, they are quick to grab it with their massive forelegs. Despite their diminutive size they are seemingly fearless about grabbing bees and other large prey.
Right: Males of Phymata pennsylvanica are typically much smaller than females. They are also darker, though not always this dark. Even in the darkest males the legs and abdomen remain pale.
Punzalan et al. (2008) argue that evolutionarily speaking, darker males have had an advantage in warming more quickly in the sun, enabling them to find females and mate even under chilly conditions.
American Insects site |
Electricity distribution is the final stage in the delivery of electricity to end users. A distribution system’snetwork carries electricity from the transmission system and delivers it to consumers. Typically, the network would include medium-voltage (1kV to 72.5kV) power lines, substations and pole-mounted transformers, low-voltage (less than 1 kV) distribution wiring and sometimes meters.
In the early days of electricity distribution, direct current (DC) generators were connected to loads at the same voltage. The generation, transmission and loads had to be of the same voltage because there was no way of changing DC voltage levels, other than inefficient motor-generator sets. Low DC voltages (around 100 volts) were used since that was a practical voltage for incandescent lamps, which were the primary electrical load. Low voltage also required less insulation for safe distribution within buildings. The loss in a cable is proportional to the square of the current, and the resistance of the cable. A higher transmission voltage would reduce the copper size to transmit a given quantity of power, but no efficient method existed to change the voltage of DC power circuits. To keep losses to an economically practical level the Edison DC system needed thick cables and local generators. Early DC generating plants needed to be within about 1.5 miles (2.4 km) of the farthest customer to avoid excessively large and expensive conductors.
ELECTRICAL DISTRIBUTION SYSTEMS
Introduction to the course: this course is provided in a question & answer format and is divided into 5 chapters, it will become extremely useful to you:
• If you want to know the parameters of the induction motors, their effect on the starting and normal performance of the machine.
• If you want to analyze an existing a.c. machine or evaluate a new one for its steady state or transient state including starting and short circuit.
• If you want to know the major components in the power distribution systems and how each component is defined.
• If you want to calculate the line and cable constants from the information found in standard tables.
• If you want to know the different types of breakers, starters and switchgear assemblies. Also, if you want to know how they are defined.
• If you want to do the necessary calculations to size the load breaking/interrupting/disconnecting devices for normal and fault conditions.
• If you want to know the types and sources of power line disturbances. Also, if you want to know the effects of such disturbances on the major components of the power systems and the methods of reducing these damaging effects.
• If you want to know the effects of using local capacitors in increasing the circuit capacity anyhow to size capacitors to improve the p.f. in motor circuits.
• If you want to quantify the effect of direct and indirect lightning strokes on overhead distribution systems.
• If you want to know what are the data that have to be available in order to perform any of the following studies: TRV, stability, load flow, fault/co-ordination, motor starting, reliability and switching transients.
• If you to know the procedure to calculate the following: basic values including base and p.u.values, load flow, fault current/voltage sensitivity, motor starting, reliability studies for simple radial systems.
• If you want to know how steel properties, switchboard instruments, meters, relays are defined and what are the major modules of PLC plus the building blocks of an office automation system.
• If you want to know the calculations to be performed if a major power transformer is to be protected against short circuits or overloads.
• If you want to know what are the essential programs and data for the power systems analyst (or any other individual involved in electric power distribution and studies – for that matter).
Questions & Answers :
Electric power distribution system?
The electricity supply system is divided into the transmission system and thedistribution system. The distribution system is the part of the system which supplies the consumer -in the UK, we are talking about voltages of 33 kV, 11 kV, and 400/230 V.
What is the role of Global Distribution Systems?
A computer reservations system or central reservation system CRS is a computerized system used to store and retrieve information and conduct transactions related to air travel. Originally designed and operated by airlines, CRSes were later extended for the use of travel agencies. Major CRS operations that book and sell tickets for multiple airlines are known as global distribution systems (GDS).
What is low voltage distribution system?
In the Typical sense its anything 50 volts or below. When speaking of service voltages its 600 volts or below. The threshold of 50 volts is believed to be the point where skin will resist shock so a lessor hazard is encountered.
What is the purpose of electrical distribution system?
Exactly what it sounds like. It is used to get electricity from the generation plant to the customers. It can consist of many different voltage levels.
What is the meaning of feeder in electrical distribution systems?
Feeders are conductors which connect the consumers with the sub-station. Tapings to feed current to the consumers are NOT taken from the feeders. Therefore, its current loading remains the same alo
What is the first phase of installing the BEAR electrical distribution system?
providing mission essential power
What is meaning of distribution in electrical power system?
Distribution means taking the Electrical power to different usage points where power is needed
List possible symptoms of a problem with the electrical system of a PC?
1. Memory errors, data errors, brownouts, or reboots are symptoms of electrical system problems.
The classification of EPR (up to 35KV) cables is as follows: the voltage class, the conductor material/size (which is function of the normal/overload/short circuit current values and the installation method/configuration), the insulation thickness (whether 100% or 133%), jacketed or unbracketed, neutral size (either full or 1/3 rating), cable in conduit configuration/direct buried or concrete encased conduits.2) How would underground XLPE (cross linked polyethylene) cables classified?The classification of XLPE (up to 46KV) cables is as follows: the voltage class, the conductor material/size, insulation thickness, jacketed or unbracketed, neutral (concentric neutral and rating full or 1/3 main conductor) or shielded (Cu tape), single or 3-conductor cables, jacket-type(whether encapsulated or sleeved), the use of strand-fill or water blocking agent between the insulation and jacket.
3) What are the defining parameters of cables?
The defining parameters can be classified broadly into dimensional, insulation material properties and current carrying capacity. For dimensional parameters, conductor size/number of strands/type of strands, diameter over conductor, diameter over insulation, diameter over insulation screen, number and size of neutral conductors or tape details (thickness, width & lap type) and diameter over the jacket are the defining data. Other important data are: weight/1000 ft length, size of reels and length/reel. The insulation/jacket defining parameters are: before an dafter aging tensile strength and elongation, hot creep elongation/set, dielectric constant,capacitance (SIC) during and after the stability period, insulation resistance constant, water absorption properties. The last set of defining parameters are the current levels at the nominal voltage under the different operating conditions which are function of: the layout and proximity of current carrying cables, the method of laying/pulling of cables, provision of future additional loads with their corresponding maximum allowable voltage drop and finally the maximum acceptable temperature rise & duration for the cable insulating material.
4) What are the factory and site tests to be performed on cables?
The different types of tests that are performed on cables at the factory are: partial discharge, DC resistance of central conductor, AC high voltage dielectric withstand ability, DC high understandability, insulation resistance, physical dimensions of cable components, cold bend, low temperature impact, jacket integrity, water penetration and high temperature drip test for the-strand fill (if applicable). For conductor shield the tests are: volume resistivity, elongation at rupture, void and protrusions, irregularities verification. For the insulation are: tensile strength(aged and unwaged)/elongation at rupture (aged and unwaged)/dissipation factor (or power factor)/hot creep (elongation and set)/voids and contamination/solvent extraction (if applicable).For the insulation shield are: volume resistivity/elongation at rupture/void and protrusions irregularities/strippability at room temperature and at -25C/water boil test. For the jacket are:tensile strength, elongation at rupture (aged and unwaged), absorption coefficient (of water), heat shock and distortion. On the cable the following tests may be performed: structural stability and insulation shrink back for certain insulation materials. The tests performed on site are: visual inspection, size/ratings verification and D.C. withstand ability tests at voltage level below those used in the factory.
5) What are the defining parameters for low voltage secondary cables?
The defining parameters for l.v. secondary cables are: material of phase conductor, number of strands, class of strand, type of conductor (ie. concentric, compact or compressed), conductor size, insulation thickness, over all diameter per cable, overall diameter per assembly (ie. triple xor quadruples), the neutral conductor size (equal to the phase or reduced), if applicable,insulation and jacket materials, jacket thickness and the weight per assembly per 1000 ft length.
6) What are the different types of transformers found in distribution systems?
The different types of transformers found in distribution systems are: Power (up to 10MVA)liquid filled (oil), power (over 10 up to 100 MVA) oil filled with radiators/fans (one or 2 sets),single phase distribution transformers/oil filled (with or without radiators/fans) up to 500 KVA,three phase distribution transformers/oil filled (with or without radiators/fans) up to 1.5MVA,dry type power transformers/3 phase 300 KVA to 2MVA or silicone filled or epoxy resin insulated for indoor installations. All oil filled transformers are installed outdoor unless special layout with fire proof (resisting) material and appropriate barriers are used, then indoor installation is possible. Distribution transformers can be of the pole mounted, vault surmounted type. The primary voltage of power transformers can be as high as 750 KV, though the most common are 345KV, 220KV, 115KV, for distribution transformers as high as 72KVthough the most common are 34.5, 25KV (27.6KV), 15KV.
7) What are the different types of overhead switches, pad mounted switchgear and those of lightning arresters?
The different types of overhead switches are: either single or three phase, either manually operated or electric/manual operated, either local control or remote/local control, oil insulated or air or SF6. The different types of pad mounted switchgear are: either manually or manually/motor operated, controlled locally or locally/remotely, air or oil or SF6/vacuum insulated, protective devices are either fuses or electronic devices. The configuration will,generally, have four compartments with any combination of fuse or interrupter, switch, solid or empty compartment. The different types of lightning arr esters are: station, intermediate,distribution (heavy duty, normal or light duty) and may be riser pole type.
8) What are the standards that govern distribution transformers? How are distribution transformers defined?
The standards that govern distribution transformers are: CSA “Single phase & three phase distribution transformers” Std. C2, CSA “Dry type transformers” C9, CSA “Guide for loading Dry-type distribution and power transformers” C9.1 and CSA “Insulating oil” C50. The distribution transformers are defined as follows: the voltage ratings (insulation class level of primary -h.v.- winding, the primary and secondary windings rated voltage), short circuit capability for a fault on the bushings of the transformer (current value and its corresponding duration), dielectric test values (applied voltage for 1 minute, full wave and chopped BIL anytime to flash over for the chopped), outdoor transformer bushings ratings (defined by their insulation class, 60HZ 1 minute/dry, 10 second/wet dielectric withstand ability, the full wave and chopped BIL), audible sound levels and induced voltage tests.
9) How are wooden and concrete poles defined?
The wooden poles are defined as follows: the class (1 to 7-4500LB to 1200 minimum horizontal breaking load when applied 2 ft. from pole top), the minimum circumference at pole top level(27″ to 15″), length of pole (25 to 110 ft, generally), minimum circumference at the ground level(distance from butt), the wood species (Western Red Cedar, Southern Yellow Pine, Douglas Fir,Western Larch), the treatment against attack from fungi and insects (eg. creosote oil, ammonicalcopper fatty acid, pentachlorphenol or chromated copper arsenates) and the weight per pole.The concrete poles are defined accordingly: ultimate load (class A to J, 600 LB to 4500 LB,respectively), the length, the manufacturing process (regular or prestressed class), the steelreinforcing rods (cage) tensile strength, the diameter, the raceway diameter, spacing anddiameter of holes in the pole, grounding bars (galvanized or coated) surface treatment.
10) What are the different applications of oil switches and what are their defining parameters?
The different applications of overhead oil switches in utility distribution systems are: generalpurpose for inductive and resistive loads & capacitor (capacitive current switching). Thedefining parameters are: the rated maximum voltage, the basic impulse level, the dielectric withstand, continuous current, inductive load switching, capacitive switching current, makingcurrent, momentary current, short time current rating; for the control circuit: nominal and rangeof operating voltage, trip coil current. The weight, dimensions, oil volume and speed of operation for the switch are also important defining data. The other two devices that may use oilas the switching medium are the sectionalizes and reclosers.
11) How are overhead air switches classified?
The following is the classification of the air insulated switches according to their breaking type:side break switches, vertical break and double break. The different types of mountings for suchswitches are: upright, vertical, triangular, tiered outboard mounting and pedestal. The insulatorsof the switch may be epoxy or porcelain, the base is insulated or steel.
13) What are the important parameters by which lightning arresters are defined?
14) How would copper conductors be defined?
The construction of copper conductors is defined as follows: cross section area, class of conductor (indication of degree of flexibility), number of wires, diameter of wire, tensilestrength, elongation, diameter of conductor, type (concentric lays, compact or compressed) andweight per 1000 ft.
15) How would ACSR (aluminum conductor steel reinforced) and ASC (aluminumstranded conductor) be defined?
The defining parameters for aluminium conductor steel reinforced designs are: the Al area, thetotal conductor area, steel/Al area ratio, number of Al wires, diameter of Al wire, area of steelwire, diameter of steel wire, diameter of core (steel), diameter of conductor, tensile strength,AWG size, total conductor weight per 1000 ft. and the ratio of Al weight to the total weight. Thedefining parameters for aluminium stranded conductors are: the aluminum conductor area, thequantity (number) of Al wires, diameter of each wire, the diameter of the conductor, the tensilestrength, the elongation and the total weight of conductor per 1000 ft.
16) How would AASC (aluminum alloy stranded conductor) and self-dampening/compact ACSR be defined?
The defining parameters for Aluminium alloy stranded conductors are: Al alloy area and theequivalent Al area, number of Al alloy wire, diameter per wire, overall diameter of conductor,AWG/KCMIL, weight/1000 ft, tensile strength and elongation. The defining parameters for self-dampening conductors and compact ACSR are: aluminium area, total conductor area, steel to Alarea (ratio), number of Al wires, number of steel wires, core (steel) diameter, overall conductordiameter, conductor weight/1000 ft length, ratio of Al weight to total weight, tensile strengthand elongation.
17) What are the different types of cable splices and terminations?
The different types of cable splices are: tapped, heat shrinkable and cold shrinkable. The majorcomponents of a splice are: cable adapters, splice housing, conductor contact, conductive insert,retaining rings/tube, interference fit and grounding eye. The different types of cableterminations are: the fully taped, moulded stress cone and tape, one piece moulded cabletermination, porcelain terminators, heat shrinkables and potheads.
18) What are the different types of connectors and elbows?
The different types of connectors are: the mechanical (for Al and/or Cu conductors), thecompression, the wedge (to connect main conductors to taps), hot line clamps (the mainoverhead to equipment connection) and the stirrups (wedged or bolted). The two types of separable connectors (elbows) are the dead break and load break. The major components of elbows are: the connector, the moulded insulating body, cable adapter, the test point, the semi-conducing shield, semi-conducting insert, grounding tabs the pulling eye, the probe (for loadbreak, it is field replaceable with abelative material arc follower).
19) What are the design tests performed on the separable connectors?
The design tests performed on the elbows are: partial discharge inception and extinction levels(corona), withstand power frequency voltage capability (a.c. and d.c.), impulse voltagewithstand level, short time current rating, switching test, fault closure rating, current cycling forinsulated and uninsulated connectors, cable pullout from elbow (connector), operating force,pulling eye operation, test point cap pulling test, shielding test, interchangeability, acceleratedthermal and sealing life, test point capacitance (voltage presence indication) test.
20) What are the different types of insulators, their material and characteristics?
The different types of insulators are: the pin, the suspension and the post (vertical andhorizontal). The different insulators materials are: porcelain, glass, fibreglass, polymer andsilicone. The properties of insulators can be broadly classified into: mechanical, electrical,environmental and maintenance. The mechanical can further be classified into: different loadsthe insulators is subjected to due to weights of supported components, short circuit, ice, etc.(normal, design, cyclic, torsional, overloads – exceptional), safety factors, single or multipleinsulator assemblies and aging effect on strength of insulator. The electrical parameters definingthe insulators are: BIL, power frequency withstandability (dry, wet and flashover level), leakagedistance, power arcs effect, performance under steep front voltage wave, clearances andperformance under contamination. The environmental characteristics can be further broke down into: insulator ageing under ultra-violet rays and dry arcing, type of contamination, radiointerference voltage, washing requirements, corrosive environments and temperature range.
21) What are the major information obtained from a distribution system SCADA?Show ablock diagram of the major components of a SCADA (system supervisory control & dataacquisition). Sketch a diagram to show a typical automated distribution system with powerand communication lines.
The major information obtained from a SCADA in a power distribution system are: indications(eg. state change like opening or closing of circuit breakers, load break switches, reclosures,disconnects, operation of a relay or fault indicators) of events or alarms, levels (eg. oil level, tapchanger position, reading from pressure gauges), pulses (eg. energy meter counters),measurands (eg. current, voltage, power reading, temperature of oil or windings, leakagecurrent).
22) What are the basic modules in a PLC (programmable logic controller) system? Sketcha front plate of 2 of the basic modules. Sketch a block diagram showing the interrelation of the major modules.
The basic modules of a PLC system are: the processor, the input/output (they can further beclassified into digital and analog), process control (proportional/integral/derivative), steppermotor, interface modules (they can be further classified into: local and remote, local and remotetransfer, network, network transfer, multimedia network interface, peripheral devices (theyinclude loader/monitor, process control stations, CRT programmers, hand held programmers,tape loader). |
Central America is the region of North America located between the southern border of Mexico and the northwest border of Colombia, in South America. Some geographers classify Central America as a large isthmus, and in this geographic sense it sometimes includes the portion of Mexico east of the Isthmus of Tehuantepec, namely the Mexican states of Chiapas, Tabasco, Campeche, Yucatán and Quintana Roo. However, Central America is much more commonly understood to correspond with the nations between Mexico and Colombia; Belize, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua and Panama.
The region has made several attempts at political unity since its independence from Spain in the nineteenth century, though the region remains divided today.
The area considered Central America comprises an area of approximately 202,265 square miles (523,865 km²) and a width between the Pacific Ocean and the Caribbean Sea ranging from about 350 to about 30 miles (560 km to 50 km).
Geopolitically, Central America has traditionally consisted of the following countries:
|Name of territory,
(1 July 2005 est.)
|Costa Rica||51,100||4,327,000||85||San José|
|El Salvador||21,040||6,881,000||327||San Salvador|
Many modern definitions of Central America include Belize and Panama, neither of which existed upon the formation of the Federal Republic of Central America, a short-lived union created after most of the region gained independence from Spain in the nineteenth century. The territory now occupied by Belize was originally contested by the United Kingdom and the Spanish Empire and, later, Guatemala (which has considered it, wholly or partially, an eastern department); it became a British colony (British Honduras) in 1871 and gained independence in 1981.
Panama, situated on the Isthmus of Panama, is sometimes regarded as a transcontinental territory. Today, it is often considered a part of North America alone; however, for much of its history Panama has been connected to South America. Panama was originally a possession of the Viceroyalty of New Granada, and then, following independence, became a part of la Gran Colombia (Greater Colombia). Only after independence from Colombia in 1903 did some begin to regard Panama as a strictly North American entity.
Fertile soils from weathered volcanic lavas have made it possible to sustain dense populations in the agriculturally productive highland areas. The majority of Central America rests on the Caribbean Plate and it surrounded by the Cocos Plate, North American Plate and the Nazca Plate. The geology of Central America is active, with volcanic eruptions and earthquakes occurring from time to time. The meeting point of the Caribbean and Cocos plates causes most of the geologic instability in the region. In 1931 and 1972 earthquakes devastated Managua, the capital of Nicaragua. The Cocos Plate is moving in a Northeastward direction at about 30 feet per century relative to the Caribbean Plate.
About four-fifths of the region is hilly or mountainous. More than 40 volcanoes lines up along the Pacific coast from Guatemala to Costa Rica. Half the volcanoes in the region are considered dormant, while one-fourth are extinct, the remaining volcanoes are active and together make up the most active volcanic region in the Americas. The highest point in Central America is Volcán Tajumulco in Guatemala which is an extinct volcano and is 13,845 feet (4,220 m) high.
The narrowest part of The Americas, Central America is the site of the Panama Canal as well as the proposed, but never-completed, Nicaragua Canal.
The climate is mainly tropical although this varies with altitude, distance from the ocean, and latitude. Temperature can range from over 100° F to below 46° F mainly depending on altitude and moisture content. Rainfall across Central America varies from north to south and from the Pacific coast to the Caribbean coast. Between May and November, and especially from August to October, the Caribbean coast of northern Central America is prone to hurricane damage.
Central America boasts a rich diversity in both flora and fauna, however to a lesser extent than South America. Central American forests are richly populated in birds, reptiles and insects, whereas mammals are much less common. Birds that live in the isthmus include parrots, hummingbirds, eagles, toucans and numerous migratory birds. Snakes can be found in all parts of Central America, as well as sea turtles, lizards, iguanas, the caiman and abundant species of tree frogs. Many of the endemic Central American species are endangered or near extinction due to deforestation, hunting and the pressure of human population growth on the area.
The vegetation of Central America is diverse and can be described as a tropical rain forest for the eastern half of the low lying portion of the region. The high interior region of Central America is mainly covered in montane forest.
In pre-Columbian times, most of modern Central America was part of the Mesoamerican civilization. The Native American societies of Mesoamerica occupied the land ranging from central Mexico in the north to Costa Rica in the south. The pre-Columbian cultures of Panama traded with both Mesoamerica and South America, and can be considered transitional between those two cultural areas.
After the Spanish conquest in the sixteenth century, most of the inhabitants of Central America shared a similar history. The exception was British Honduras (the modern-day nation of Belize), a sparsely populated area that was leased by the Spanish Crown to Great Britain for 150 years for the exploitation of certain natural dyes. Later the region was claimed as a colony by the English Crown and was never to return to Spain or Guatemala, which claimed it as its territory until the 1970s. British Honduras for the English and Belice for the Spaniards and Guatemalans, gained its independence from Great Britain in 1973 and adopted the name "Belize."
From the sixteenth century through 1821 Central America formed the Captaincy General of Guatemala, sometimes known also as the Kingdom of Guatemala, composed by the states of Chiapas (now part of Mexico), Guatemala (including present day Belize), El Salvador, Honduras, Nicaragua, and Costa Rica. Officially, the Captaincy was part of the Viceroyalty of New Spain and therefore under the rule of the Spanish viceroy in Mexico City. It was, however, administered not by the viceroy or his deputies, but by an independently appointed Captain General headquartered first in Antigua, Guatemala and later in Guatemala City.
In 1821 a congress of Central American criollos declared their independence from Spain, effective on September 15th of that year. (That date is still marked as the Independence Day by most Central American nations.) The Spanish Captain General, Gabino Gaínza, sympathized with the rebels and it was decided that he should stay on as interim leader until a new government could be formed. Independence was short-lived, for the conservative leaders in Guatemala welcomed annexation by the First Mexican Empire of Agustín de Iturbide on January 5, 1822. Central American liberals objected to this, but an army from Mexico under General Vicente Filisola occupied Guatemala City and quelled dissent.
When Mexico became a republic the following year, it acknowledged Central America's right to determine its own destiny. On July 1, 1823, the congress of Central America declared absolute independence from Spain, Mexico, and any other foreign nation, and a Republican system of government was established.
In 1823 the nation of Central America was formed. It was intended to be a federal republic modeled after the United States of America. It was provisionally known as "The United Provinces of Central America," while the final name according to the Constitution of 1824 was "The Federal Republic of Central America." It is sometimes incorrectly referred to in English as "The United States of Central America." The Central American nation consisted of the states of Guatemala, El Salvador, Honduras, Nicaragua, and Costa Rica. In the 1830s an additional state was added, Los Altos, with its capital in Quetzaltenango, occupying parts of what is now the western highlands of Guatemala and part of Chiapas (now part of Mexico), but this state was reincorporated into Guatemala and Mexico respectively in 1840.
Central American liberals had high hopes for the federal republic, which they believed would evolve into a modern, democratic nation, enriched by trade crossing through it between the Atlantic and the Pacific oceans. These aspirations are reflected in the emblems of the federal republic: The flag shows a white band between two blue stripes, representing the land between two oceans. The coat of arms shows five mountains (one for each state) between two oceans, surmounted by a Phrygian cap, the emblem of the French Revolution.
In practice, however, the federation faced insurmountable problems. The liberal democratic project was strongly opposed by conservative factions allied with the Roman Catholic clergy and wealthy landowners. Transportation and communication routes between the states were extremely deficient. The bulk of the population lacked any sense of commitment towards the broader federation perhaps largely owing to their continued loyalty to the Roman Catholic Church in Spain. The federal bureaucracy in Guatemala City proved ineffectual, and fears of Guatemalan domination of the union led to protests that resulted in the relocation of the capital to San Salvador in 1831. Wars soon broke out between various factions both in the federation and within individual states. The poverty and extreme political instability of the region prevented the construction of an inter-oceanic canal (Nicaragua Canal and Panama Canal), from which Central America could have obtained considerable economic benefits.
Various attempts were made to reunite Central America in the nineteenth century, but none succeeded for any length of time. The first attempt was in 1842 by former President Francisco Morazán, who was quickly captured and executed. The abortive attempt aimed to restore the union as the Confederation of Central America and included El Salvador, Guatemala (which withdrew early), Honduras, and Nicaragua. This first attempt lasted until 1844. A second attempt was made and lasted from October to November 1852, when El Salvador, Honduras and Nicaragua created a Federation of Central America (Federacion de Centro America). Guatemalan President Justo Rufino Barrios attempted to reunite the nation by force of arms in the 1880s and was killed in the process, like his 1842 predecessor. A third union of Honduras, Nicaragua, and El Salvador as the Greater Republic of Central America or "Republica Mayor de Centroamerica" lasted from 1896 to 1898. The latest attempt occurred between June 1921 and January 1922 when El Salvador, Guatemala and Honduras formed a second Federation of Central America. This second Federation was nearly moribund from the start, having only a Provisional Federal Council made up of delegates from each state.
Despite the failure of a lasting political union, the concept of Central American reunification, though lacking enthusiasm from the leaders of the individual countries, rises from time to time. In 1856-1857 the region successfully established a military coalition to repel an invasion by U.S. adventurer William Walker. Today, all five nations fly flags that retain the old federal motif of two outer blue bands bounding an inner white stripe. (Costa Rica, traditionally the least committed of the five to regional integration, modified its flag significantly in 1848 by darkening the blue and adding a double-wide inner red band, in honor of the French tricolor).
In 1907 a Central American Court of Justice was created. On December 13, 1960, Guatemala, El Salvador, Honduras, and Nicaragua established the Central American Common Market ("CACM"). Costa Rica, because of its relative economic prosperity and political stability, chose not to participate in the CACM. The goals for the CACM were to create greater political unification and success of Import Substitution Industrialization policies. The project was an immediate economic success, but was abandoned after the 1969 "Soccer War" between El Salvador and Honduras.
The Central American Parliament, also known by the abbreviation "Parlacen" (from the Spanish Parlamento Centroamericano) is a political institution devoted to the integration of the Central American countries. The Parlacen represents a modern renewal of the historic Federal Republic of Central America which existed from 1823 to 1840, though not including Costa Rica but including Panama and the Dominican Republic.
The Parlacen has its more recent origins in the Contadora Group, a project launched in the 1980s to help deal with civil wars in El Salvador, Guatemala and Nicaragua. Although the Contadora was dissolved in 1986, the idea for Central American Integration remained, and its works were taken by the Esquipulas Peace Agreement, which, among other acts, agreed to the creation of the Central American Parliament.
In spite of its efforts to promote the Esquipulas Agreement, Costa Rica has not yet ratified and is consequently not represented in the Parlacen. It has been seen by many as a "white elephant."
The Parlacen has three branches: Plenum, Board of Parliament, and Secretariat. If ten members of at least two or more countries join together, they can from a Parliamentary Group.
The Esquipulas Peace Agreement was an initiative in the mid-1980s to settle the military conflicts that had plagued Central America for many years, and in some cases (notably Guatemala) for decades. It built upon work laid by the Contadora Group from 1983 to 1985. The agreement was named for Esquipulas, Guatemala, where the initial meetings took place.
In May 1986, a summit meeting, "Esquipulas I," took place, attended by the five Central American presidents. On February 15, 1987, Costa Rican President Óscar Arias submitted a Peace Plan which evolved from this meeting. During 1986 and 1987, the "Esquipulas Process" was established, in which the Central American heads of state agreed on economic cooperation and a framework for peaceful conflict resolution. The "Esquipulas II Accord" emerged from this and was signed in Guatemala City by the five presidents on August 7, 1987.
Esquipulas II defined a number of measures to promote national reconciliation, an end to hostilities, democratization, free elections, the termination of all assistance to irregular forces, negotiations on arms controls, and assistance to refugees. It also laid the ground for international verification procedures and provided a timetable for implementation.
The United States government refused to recognize the agreement due to its de facto recognition of the Sandinista regime, which the US government rejected as illegitimate and undemocratic. The US declined on the agreement thus it was unsuccessful. However some have said it was successful as they considered it a sly political attack on Sandinista government of Nicaragua. Eventually the agreement was rewritten and in subsequent years, Esquipulas laid the groundwork for the 1990 Oslo Accord (not to be confused with the 1993 Oslo Accords between the Israeli government and the Palestine Liberation Organization (PLO)). This was a preliminary agreement between the Guatemalan National Reconciliation Commission (CNR) and the Guatemalan National Revolutionary Unity (URNG) which brought to an end more than three decades of strife in Guatemala. It also inspired the signing of a general peace agreement in El Salvador. Arias' efforts on behalf of the Esquipulas Peace Agreement earned him the 1987 Nobel Peace Prize.
Central America has maintained one of the highest population growth rates in the world, with the estimated population in 2007 at over 40,500,000. This has risen from a population of 10 million in the early 1950s. The population density is 77.3 inhabitants per square kilometer, though in reality, the population is distributed very unevenly throughout the region.
The dominant language of the region is Spanish and is the official language in six of the nations. Belize's official language is English, which is also the lingua franca along much of the Caribbean coast. Many of the Native tribes speak only their native tongue, though some speak Spanish while a large number speak more than one native language.
During colonial times the native populations were converted to Catholicism, of which the majority of Central Americans follow to this day. Among the Native peoples the Catholic faith was blended into the native religious practices. The original beliefs and rituals have become a part of the Catholic faith of the region.
The population of Central America consists of a large majority (two-thirds) of people of mixed ancestry. It is estimated that approximately 60 percent are of mixed European and American Indian descent (called "ladinos" in Guatemala and "mestizos" elsewhere), with an additional 5 percent being descended from European and African ancestors (referred to as "mulattoes"), and one percent descending from a mix of native and black ancestors. Amerindian (original indigenous population) comprise 20 percent of the population. Those of strictly European ancestry make up approximately 12 percent, with the remainder claiming descendency from Chinese and East Indian indentured servants.
The population breakdown between nations in the region is approximated at one-third in Guatemala, one–sixth in El Salvador, one–sixth in Honduras, one–eighth in Nicaragua, one–tenth in Costa Rica, and one–twelfth in Panama. Less than one percent of the population resides in Belize. The population density of each nation varies greatly. The following table shows the population and area of each country with its respective density:
The white ethnic group, or White Latin Americans, have an approximate population of 5,380,885 inhabitants, of which more than half are located in Costa Rica, followed by Nicaragua with almost one million. El Salvador and Guatemala also have significant white populations.
The mestizo population (mixed Amerindian and Caucasian) is formed by 27,456,772 inhabitants, occupying the majority of the Central American population. All seven republics have significant Mestizo populations, the majority of which are located in Guatemala and Honduras.
The Creole, Afro-Caribbean, and Garifuna populations form the majority of the Afro-Latin Americans in Central America, of which the majority is concentrated on the Caribbean coasts of the region. It is important to note that all these groups are distinct, speaking English, English creoles, Garifuna, Miskito, and Spanish. The highest percentage is 31 percent in Belize, where Belizean Kriol people and Garifuna were once the majority. The largest population, however, is in Nicaragua of Creole, Miskito, and Garifuna descent, also concentrated on the Caribbean coast in the area often referred to as the Mosquito Coast. In Panama a small black population was already present when the construction of the Panama Canal saw the large arrival of immigrant Afro-Caribbean people. Honduras has a small population of creole people, but the overwhelming majority of blacks are Garifuna. Although El Salvador is the only Central American country with no official black percentage, Salvadorans with some African heritage are present.
The only plurality of Indigenous people located in Central America is in Guatemala. Amerindians are small minorities in the rest of Central America.
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Problem Solving KS2 Maths. Have fun solving these Maths problems. Great activities to use Maths problem solving skills in real life scenarios. Links to a selection of printable and interactive Maths resources, great for ks2, ages 8-11 years.
Cycling Timing Challenge Video
Two cycling-mad schoolchildren are taken on a tour of the National Cycling Centre in Manchester. They meet world individual pursuit champion Sarah Storey, and are set a maths challenge related to cycling.
Traditional frog jumping puzzle. Can you swap the green and blue fogs over? How few moves does it take? What if the number of frogs were to change?
Imagine that you're walking along the beach, a rather nice sandy beach with just a few small pebbles in little groups here and there. You start off by collecting just four pebbles and you place them on the sand in the form of a square. The area inside is of course just 1 square something, maybe 1 square metre, 1 square foot, 1 square finger ... whatever.
Problem Solving Task Cards Printable
This resource contains an example of a four-step approach for a problem solving strategy and task cards split into levels. Aimed at Year six pupils. Registration required.
Properties Of Numbers Quiz
By the time they reach Year 5, the third year in KS2, children should be familiar with certain properties of numbers which they have come across in their Maths lessons. They should, for example, know the difference between multiples and factors and should also know what square numbers are. Play this quiz for 9-10 year olds and see what you have remembered.
Word Problems Interactive
Maths word problem generator. Select difficulty and number of questions, check your answers and see how you are doing with the % indicator. |
The world bee population is at its greatest trial in years, as thousands of bee populations die off each year. Scientists are trying to salvage what’s left or even possibly enforce the current bees left by breeding a new pest resistant, cold impervious superbees.
Beekeepers around the world have reported on their lowest honey crops in decades, all because of the declining honeybee populations at the hands of insecticide-resistant mites and viruses. Now, instead of introducing a new kind of pesticide, scientists are trying to breed stronger bees capable of surviving and overcoming the threats they’re exposed to.
According to the U.N., viruses and mites are responsible for the killing of 85% of bees in the Middle East, 10% to 30% of bees in Europe, and nearly a third of American bees each year. If you don’t care too much about bees, maybe you should look a bit to your stomach and see what kind of say he has in this. Consider that over 70 of the 100 crops that provide 90% of the world’s food are pollinated by bees, $83 billion worth of crops money-wise, and billions of hungry mouths human-wise.
University of Manitoba in Winnipeg researchers tried to achieve this by inserting queen bees that exhibited the required properties across colonies in Canada. They then were subjected to what’s referred to as disease pressure, in which each generation of survivors is bred for the next season, the theory being that eventually a mite-resistant brand of bees will emerge.
What they got was more than they ever hoped for; not only were the bees resistant to pests and viruses, but also fit for surviving winters – only 46% of European honeybees normally survive the winter, but these mite-resistant bees have a 75% survival rate.
It’s trivial to believe, however, that breeding mite-resistant bees will be the end of the current bee, and overall food crisis. It’s well accounted that pollution, climate change and growing devastating pesticides are also responsible for the worldwide bee decimation. |
Like a lot of technology, Roman siege weaponry was mostly developed by the Greeks and then perfected by the Romans. Ballistae, essentially giant crossbows that could fire large stones during sieges, were mostly back-engineered designs from captured Greek weapons. Using loops of twisted animal sinews for power, ballistae worked almost like springs in giant mousetraps -- when the sinews were tightly wound and then allowed to snap back, they could launch projectiles up to 500 hundred yards (457 meters). Since it was light and accurate, this weapon could also be fitted with javelins or large arrows and used to pick off members of opposing armies (as an anti-personnel weapon). Ballistae were also used to target small buildings during sieges.
Romans also invented their own siege engines called onagers (named after the wild donkey and its powerful kick) to fling larger rocks. Though they also used springy animal sinews, onagers were much more powerful mini-catapults that fired a sling or a bucket filled with either round stones or combustible clay balls. Though they were much less accurate than ballistae, they were also more powerful, making them perfect for blasting down walls and setting fires during sieges. |
Clean water and sanitation: Five facts to becoming informed and engaged global citizens
Youth can take action as engaged global citizens to help ensure people everywhere have access to clean water and sanitation by learning about Goal 6 of the UN Sustainable Development Goals.
Toilets are probably not one of the first things most people think about when they are considering ways they can help make the world a better place, but lack of access to clean water and sanitation is a major global issue affecting billions of people around the world every year. Leaders from 193 countries have agreed to ensure access to water and sanitation for all people by the year 2030, which is Goal 6 of the United Nations (UN) Sustainable Development Goals. The Sustainable Development Goals are 17 interconnected goals that seek to transform our world by ending all forms of poverty, eliminating inequalities and improving the state of the world’s natural and human-made environments through sustained multinational cooperation and efforts in the next 15 years.
By learning about, teaching about and taking action on the state of clean water and sanitation around the world, young people can play a valuable leadership role in helping to accomplish the Sustainable Development Goals. Here are five important facts and some educational resources related to Goal 6 of the Sustainable Development Goals that can help youth learn and engage as global citizens, according to the UN.
- Globally, 2.4 billion people do not have access to toilets or latrines. Earlier this year, the UN declared that access to clean sanitation is a basic human right. Without access to clean sanitation, people are not able to pursue and enjoy their other human rights, such as their right to health, life and education. The UN has found that “more than 443 million school days are lost every year due to sanitation and water related issues. Inadequate sanitation facilities are a common barrier for school attendance, particularly for girls.”
- Approximately 1.8 billion people use a source of drinking water that is fecally contaminated. That means one in four people around the world have to use water that has been contaminated by human waste, which is a potential source of deadly pathogens and diseases.
- One thousand children die every day due to preventable water and sanitation-related diarrheal diseases, which continue to be a major source of death in children under 5. “Worldwide, more than two million people die every year from diarrheal diseases. Poor hygiene and unsafe water are responsible for nearly 90 percent of these deaths and mostly affect children,” according to the UN.
- Approximately 663 million people live without access to improved drinking water sources. “An improved drinking-water source is defined as one that, by nature of its construction or through active intervention, is protected from outside contamination, in particular from contamination with fecal matter, according to the WHO/UNICEF Joint Monitoring Programme for Water Supply and Sanitation.
- Water scarcity affects more than 40 percent of the global population and is projected to rise.
Goal 6 of the Sustainable Development Goals seeks to improve the global populations access to clean water and sanitation by the year 2030 by ending open defection, reducing water pollution, increasing water-use efficiency, implementing “integrated water resources management,” protecting and restoring water-related ecosystems and expanding water harvesting, desalination, wastewater treatment and water recycling and reuse in developing countries.
Researchers at Michigan State University are engaged in efforts that will help reach the targets set out in Goal 6 of the Sustainable Development Goals. MSU professor Joan Rose, the 2016 Stockholm Water Prize Laureate, along with other university researchers, are studying innovative new materials for use in water filters as a way to make it easier and less costly for people to access clean and safe drinking water.
Adult and youth leaders can help other youth and children learn about global water quality, clean water access and sanitation issues in order to be informed and active global citizens. Here are some activities and lesson plans that can be used to help teach others about these issues:
- There’s No New Water! A National 4-H curriculum designed for high school aged youth, There’s No New Water is a high quality set of resources and activities to help young people learn “that water is a finite natural resource whose quantity and quality must be responsibly preserved, protected, used and reused.” In addition to learning about the natural water cycle and the impact of human activity on water quality and quantity, the curriculum helps youth plan and conduct a service learning project as the local level.
- Water Conservation with the Water Lion. For younger learners, Pennsylvania State Extension provides a set of resources on youth water conservation to help elementary, middle and high school-aged youth develop knowledge about the water cycle, water quality and ways to use water responsibly in their home.
- Clean Water For All. Available as a free download from World’s Largest Lesson website, Clean Water for All is a lesson plan and set of resources for helping youth ages 8-14 learn about the topics of global water pollution and clean water access. The set of activities can be led by older youth leaders or adults, and is designed as a 60-minute learning session with opportunities to extend the learning beyond the activity.
- Plan for Change: Water Toolkit. This resource and set of activities is available as a free download from Plan Canada’s website. The toolkit includes information and activities to help youth and children learn about access to safe water and clean toilets in other parts of the world.
- Get Involved and Take Action! Ready to help make a difference in the world around the issue of clean water and sanitation? Get a group of youth together to start planning a service activity for World Toilet Day (Nov. 19) or World Water Day (March 22).
MSU Extension and the Michigan 4-H Youth Development program helps to prepare youth as positive and engaged leaders and global citizens by providing educational experiences and resources for youth interested in developing knowledge and skills in these areas. To learn about the positive impact of Michigan 4-H youth leadership, civic engagement, citizenship and global/cultural programs, read our 2015 Impact Report: “Developing Civically Engaged Leaders.”
Other articles in series
- Youth play leadership role in achieving 17 global goals for sustainable development
- Goal 1: Engaging youth as leaders and global citizens to help end poverty
- Goal 2: Youth can join leaders around world in efforts to end global hunger by 2030
- Goal 3: What does the world’s deadliest animal have to do with youth global citizenship?
- Goal 4: Youth can help support the universal human right to an education
- Goal 5: Global gender equality: Five facts on Goal 5 of UN Sustainable Development Goals
- Goal 6: Clean water and sanitation: Five facts to becoming informed and engaged global citizens
- Goal 7: 5 facts related to affordable and clean energy
- Goal 8: Youth can become more informed global citizens by learning about child labor and related topics
- Goal 9: Learning about global infrastructure and innovation helps youth become global citizens
- Goal 10: Learning about global inequalities helps youth become global citizens
- Goals 11 and 12: Learning about sustainable cities and lifestyles helps youth become positive global citizens
- Goal 13: Learning about climate change can help youth become active global citizens – Part 1 and Learning about climate change can help youth become active global citizens – Part 2
- Goal 14: Will a giant, floating pile of garbage become the world’s newest country? – Part 1 and Will a giant, floating pile of garbage become the world’s newest country? – Part 2 |
Weight loss surgery candidacy is determined by several factors, but the Body Mass Index (BMI) is usually used to determine eligibility.
What is BMI?
Body Mass Index (BMI) is a number calculated from a person’s weight and height. BMI is a reliable indicator of fat content in the body. BMI can be considered an alternative for direct measures of body fat. Additionally, BMI is an inexpensive and easy-to-perform method of screening for weight categories that may lead to health problems.
How reliable is BMI as an indicator of body fatness?
The correlation between the BMI number and body fatness is fairly strong; however the correlation varies by sex, race, and age. These variations include the following examples:
- At the same BMI, women tend to have more body fat than men.
- At the same BMI, older people, on average, tend to have more body fat than younger adults.
- Highly trained athletes may have a high BMI because of increased muscularity rather than increased body fatness.
It is also important to remember that BMI is only one factor related to risk for disease. For assessing someone’s likelihood of developing overweight- or obesity-related diseases, the National Heart, Lung, and Blood Institute guidelines recommend looking at two other predictors:
- The individual’s waist circumference (because abdominal fat is a predictor of risk for obesity-related diseases).
- Other risk factors the individual has for diseases and conditions associated with obesity (for example, high blood pressure or physical inactivity). |
This language lesson teaches students how to punctuate quotations in their writing. The lesson includes research-based strategies and strategic questions that prepare students for assessments. In this lesson, students will learn how to separate signal phrases from direct quotations using commas and quotation marks. They will also learn to capitalize the first word of a direct quotation.
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Before going to the article, let’s know about one of the isotope of Xenon.
It has a half- life of 1.8 x 10 to the power 22 years, – roughly one trillion times longer than the age of the Universe.
Half-life of a radioisotope is the time required for half of the amount of a material to degrade into a more stable material. It often involve spitting out or capturing protons, neutrons, and electrons in various combinations.
Researchers announced that they have observed the radioactive decay of xenon-124.
Can you imagine observing a process that takes more than one trillion times longer than the age of the universe?
The evidence for xenon decay was observed as a proton inside the nucleus of a xenon atom converted into a neutron. In most elements subject to decay, that happens when one electron is pulled into the nucleus. In this case two protons within a xenon atom simultaneously absorbed two electrons, resulting in two neutrons, a special event called a double-electron capture. It only happens when two of the electrons are right next to the nucleus at just the right time described by the team as “a rare thing multiplied by another rare thing, making it ultra-rare”.
Thanks to XENON1T’s which was precise enough to measure the whole process. This instrument is designed to detect interactions of hypothetical dark matter particles with atoms in the 1,300 kilograms (2,866 pounds) of xenon isotope packed into the tank of the device.
The sensor captured the decay of the isotope itself, leading to a rare observation.
This is the first time to measure the half-life of this xenon isotope based on direct observation of its radioactive decay.
“It’s the longest, slowest process that has ever been directly observed, and our dark matter detector was sensitive enough to measure It.” said one of the researcher of the team, Ethan Brown from the Rensselaer Polytechnic Institute (RPI) in New York.
Article by Moumita Mazumdar |
The scientific name of a sponge is Porifera, which means pore-bearing.
Porifera. © 2004 Dlloyd
What are Sponges?
Sponges are the simplest form of multi-cellular animals. They are very diverse and come in a large variety of colours, shapes and structural complexities. They range in heights of 1-200cm and in diameters of 1-150cm. They have partially differentiated tissues, and not true tissues. Sponges don’t have internal organs. They don’t have muscles, a nervous system, or a circulatory system. Their walls are lined with many small pores called ostia that allow water flow into the sponge.
The structure of a sponge is simple. One end is attached to a solid such as a rock while the other end, called the osculum, is open to the environment. Sponges are able to get microorganisms such as algae and bacteria for food through openings. Some sponges are carnivorous and use their spicules to capture small crustaceans.
What are Sponges Made of?
Sponges are made of four simple and independent cells. The first are the collar cells, which line the canals in the interior of the sponge. Flagella are attached to the ends of the cells and they help pump water through the sponge’s body. By pumping water, they help bring oxygen and nutrients to the sponge while also removing waste and carbon dioxide. The second cells are the porocytes, which are cells that make up the pores of the sponge. Epidermal cells form the skin on the outside of the sponge. Finally, the amoebocytes exist between the epidermal and collar cells in an area called the mesohyl. They carry out functions of the sponge and help transport nutrients. They also form spicules, which are the sponge’s skeletal fibers. They work together with the collar cells to digest the food for the sponge and produce gametes for sexual reproduction.
What are Some Types of Sponge?
There are four different types of sponges from different classes: Calcarea, Hexactinellida, Demospongiae, and Sclerospongiae. They are split into the classes based on the type of spicules they have. For example, spicules may be made of calcium carbonate or a spongin fiber.
Where Do Sponges Live?
Sponges live in all types of regions all over the region. They are able to thrive in most environments. 99% of all sponges live in marine water, but some sponges made of spongin fiber live in freshwater. Sponges can be attached to surfaces anywhere as deep as 8km in the ocean on the bottom of the ocean floor. There are a higher number of sponge individuals and sponge species in the tropics of all regions because the water is warmer. They like to live in clearer waters over murky waters formed by currents. The murky waters may often clog the pores on the sponges so the sponge cannot get its nutrition and oxygen to survive.
What is their Importance to the Ecosystem?
Sponges are important in nutrient cycles in coral reef systems. Scientists believe they may be important factors to changes in water quality, whether good or bad. Scientists analyze how fast sponges breathe and the amount of nitrogen they release while doing so. Sponges collect bacteria when they filter the water around them. These bacteria are believed to be able to do many things. First, these bacteria may be able to create forms of nitrogen from the nitrogen gas in the water that may be nutritional for the sponge. They may also be able to turn ammonium from the sponge’s breathing into nitrogen gas that is then released into the atmosphere. This process would lower excess nitrogen levels in coral reefs, also preventing harmful ecosystem changes. Scientists believe that the conversion of nitrogen gas into useful nitrogen is also beneficial to the survival of other organisms in the area. They are hoping to have discovered a pathway for the removal of excess nitrogen from coral reefs.
What are Some Adaptations They Have to their Environment?
Sponges are strong animals with dense skeletons that are well adapted to their environments. As they may live almost everywhere, they adapt to the regions and surfaces they grow in. Certain sponge species are adapted to freshwater environments. Their skeleton types allow them to live in either hard or soft sediments. Their pores allow them to filter the water around them for food. Inside the sponge, there are flagella that create currents so their collar cells may trap the food. Sponges may have adapted to these feeding habits from a long time ago when food sources may have been scarce.
Sponges have strong structures that are able to handle the high volume of water that flows through them each day. By constricting certain of their openings, sponges are able to control the amount of water that flows through them. Scientists believe that sponges are colourful because the colours act as a protection from the sun’s harmful UV rays.
Sponges have been around for a very long time. This is because although the world is constantly changing, sponges are still able to respond to these changes through adapting to their environment. Sponges are also able to release toxic substances into the environment around them to make sure they have a good place to grow in.
How Do Sponges Reproduce?
Sponges may reproduce sexually and asexually. This helps keep them alive in their habitats. Most sponges are both male and female. In sexual reproduction, they may play either role. The ‘male’ sponge would release sperm into the water, which would travel and then enter a ‘female’ sponge. After fertilization in the sponge, a larva is released into the water. It floats around for a few days and then sticks to a solid to begin its growth into an adult sponge.
Sponges are also able to reproduce asexually through budding. This is when a small piece of sponge is broken off but is still able to survive and grow into another sponge. Sponges are also able to repair damages to their bodies. These characteristics of sponges are ideal because even small parts of sponges may survive in the water. Diversity is created when different sponges reproduce with other different sponges.
Information on the Internet
- Phylum Porifera description, structure, reproduction, body type, habitat
- The Secret Lives of Sponges - Solving Mysteries on a Coral Reef importance to ecosystem
- Sponge - Wikipedia, the free encyclopedia description, structure, reproduction, body type, taxonomy, pictures
- Sponges description, structure, type, reproduction
- Sponges - Phylum Poriphora description, structure, feeding, diagrams
- Introduction to Porifera structure, type, taxonomy, phylogeny |
A bit more than ten thousand years ago, a “Glaciation” ended and the climate warmed significantly. Since then, the global climate, while fluctuating, has been warmer than today’s temperatures. How do I know?
Well, there was a great scientific endeavor called the Greenland Ice Sheet Project (GISP) that core-drilled the continental ice sheet to produce a sequence of cylindrical chunks of ice that were sampled for oxygen isotope ratios which are dependent on the temperatures when that ice was first deposited as snow. Later, of course the snow was compressed into ice. Those readings indicated a clear record of temperature changes over many millennia. This is what is called a proxy and it is an accurate one. These data have been confirmed by other such studies in other parts of the world.
There were three upward fluctuations that peaked at (roughly) 1000, 2000 and 3300 years ago that today are called the Medieval, Roman and Minoan Warm Periods, respectively. There were two major downward fluctuations, one after the Roman Warm Period and one after the Medieval. The latter is referred to as the Little Ice Age. In all of the 10,000 years of the Holocene there were cold fluctuations (one at 8200 years ago) but never such an extended cold period as the Little Ice Age. Today we live in another warm fluctuation that is cooler than the Medieval warm period. It is cooler than the Roman Warm period by about another degree Celsius. The Minoan Warm period was warmer yet. Please see figure A. I should add that those warm periods are confirmed by historical accounts.
Figure A: (upper graph) Greenland ice core temperature proxies for the last 10500 years
The lower graph is a proxy measure of Carbon Dioxide concentration. But, that is another fact. |
In the previous article, we discussed “What are the Hydrogel materials used to make contact lenses?”. In this article, let’s talk about “What is an aspheric lens?”.
What is an aspheric lens?
Strictly speaking, any lens with a refractive surface that is not a sphere is an aspheric lens, including ordinary astigmatism lens, progressive multi-focal lens, Aspheric apical lens, etc. But customarily, our daily aspheric lens refers to the Aspheric apical lens. From the center of the lens to the periphery, the radius of curvature increases (the surface of the lens flattens out).
The origin of aspheric lens
The Visby glasses, unearthed in Gotland, Sweden, are the earliest aspheric lens found. The Vikings in the 11th century used it as a magnifying glass, and some of the best ones were made of silver, making them look like handicrafts. In 1667, Francis Smethwick grinds the first high-quality aspheric lenses and presents them to the Royal Society. That's a telescope with three aspheric elements. In 1956, Elgeet, which originally designed and manufactured optical instruments for the U.S. Navy, produced the world's first mass-produced aspheric lens for photography (Golden Navitar 12mm F1.2) for a 16mm film machine. Today, aspheric lenses are found in everything from tall telescopes to missile guidance systems to camera lenses. In the glasses we wear, the aspheric lens is familiar to consumers.
Types of aspheric lenses
There are two types of aspheric lenses: single aspheric surface (single aspheric surface for short, different from the outer aspheric surface and inner aspheric surface) and double aspheric surface (double aspheric surface for short). For the outer aspheric surface, convex is an aspheric surface and concave is a spherical surface. For the inner aspheric surface, a convex surface is a sphere, and a concave surface is an aspheric surface. In addition to correcting aberrations, the double aspheric lens also improves the effective field of vision compared to the single aspheric surface. When people's eyes look through the edge of the lens to see things, like driving when looking at the reflective mirror, it often affects vision because of the large aberration at the edge of the lens. Previous designs of aspheric plates have analyzed a single ray of light passing through the center of the pupil. Wavefront technology controls the entire beam of light passing through the pupil, eliminating high-order aberrations.
Thank you for your time in reading our passage “What is an aspheric lens?”. For more information about sunglasses and eyeglasses, please continue to follow koalaeye.com. Also, it is welcome to share and forward to Facebook and Twitter. |
Oscilloscopes (or scopes) test and display voltage signals as waveforms, visual representations of the variation of voltage over time. The signals are plotted on a graph, which shows how the signal changes. The vertical (Y) access represents the voltage measurement and the horizontal (X) axis represents time.
Sampling is the process of converting a portion of an input signal into a number of discrete electrical values for the purpose of storage, processing and display. The magnitude of each sampled point is equal to the amplitude of the input signal at the time the signal is sampled.
The input waveform appears as a series of dots on the oscilloscope display. If the dots are widely spaced and difficult to interpret as a waveform, they can be connected using a process called interpolation, which connects the dots with lines, or vectors.
Trigger controls allow you to stabilize and display a repetitive waveform.
Edge triggering is the most common form of triggering. In this mode, the trigger level and slope controls provide the basic trigger point definition. The slope control determines whether the trigger point is on the rising or the falling edge of a signal, and the level control determines where on the edge the trigger point occurs.
When working with complex signals like a series of pulses, pulse-width triggering may be required. With this technique, both the trigger-level setting, and the next falling edge of the signal must occur within a specified time span. Once these two conditions are met, the oscilloscope triggers.
Another technique is single-shot triggering, by which the oscilloscope will display a trace only when the input signal meets the set trigger conditions. Once the trigger conditions are met, the oscilloscope acquires and updates the display, and then freezes the display to hold the trace. |
Bursitis is inflammation of a bursa. A bursa is a thin, fluid filled sac that protects tendons, which are the tissues that connect muscles to bones. The bursa functions to reduce friction between tendons and the bones, allowing the tendon to glide smoothly over the bone.
Acute bursitis may be caused by trauma to the area, or over use of a joint. The repeated motion of a muscle-tendon unit causes friction in the bursa, causing inflammation and swelling with fluid. Chronic bursitis is usually caused by long term overuse; the bursa thickens and no longer functions well. Symptoms of bursitis include pain in the area of the bursa, swelling, redness, decreased motion and function of the affected limb. |
In Western countries, atopic diseases – eczema, asthma, and rhinoconjunctivitis – have been on the rise for decades. However, children raised on traditional farms are protected from childhood atopic diseases – in general, they do not develop sensitization to common allergens, as for example grass and birch pollen. The timing and duration of exposure to the farming environment seems to play a critical role in decreasing the risk of developing respiratory allergies, with the most beneficial effects seen in people exposed before birth and continuously thereafter.
Now, results from a study titled “Become a farmer and avoid new allergic sensitization: Adult farming exposures protect against new-onset atopic sensitization” show that the positive effects induced by growing up on farms are also seen in adults who move to farming areas – these adults experience a considerable reduction in symptoms of hypersensitivity and allergy. Although the study does not identify specific factors responsible for the beneficial effect of farming, it emphasizes that “working on a farm has a protective effect against ongoing or newly developing sensitization to common allergens, independent of childhood farm exposure.”
What are potential factors at the basis of the beneficial effects associated with farming? A previous study carried out in an animal model shows that growing up on a farm directly influences the regulation of the immune system and decreases sensitivity to food proteins. This effect seems to depend on an increased number of regulatory T-lymphocytes, the cells that damp down the immune response.
Results from two additional studies indicate that children living on farms are exposed to a wider range of microbes than children living in the same areas (but not on farms) – the investigators conclude that such exposure explains why asthma and atopy are not that common in children growing up in a farming environment.
All together, one of the factors responsible for the beneficial effects of farming is likely to involve the changing relationship between microbes and our immune system. City dwellers no longer encounter the large variety of microbes and parasites that co-evolved with us since the dawn of humanity. These microbes and parasites shaped our immune system in a beneficial way – when they go missing, some components of our immune system may get out of order and become over-reactive.
Copyright © 2014 Immunity Tales. |
Target: Grades 5-12
Length: 12 minutes 15 seconds
Plants in Space investigates the effects of corn plants grown onboard the Space Shuttle in orbit. Elementary students assist in the experiment by growing control plants in a one gravity environment on Earth. Plant growth terms such as geotropism and phototropism are explained. Students viewing the program can participate in the experiment by growing similar plants in their classroom. Instructions for the control experiment are contained in the accompanying guide. |
Frederick Douglass Biography for Kids
Frederick Douglass was one of the most famous abolitionists in American history. He was born near Hillsboro, Maryland in February of 1818. He was born into slavery and was separated from his mother when he was a baby. Douglass never knew his father and was moved to different residences throughout Maryland during his childhood. At the age of 12, Frederick began receiving reading lessons from the wife of his “master,” even though it was illegal to teach slaves to read. Frederick proved to be a quick study and was soon reading newspapers, magazines, and books. Through his reading of political journals, Frederick realized the horrors of slavery. In deed, many slaveholders endeavored to keep slaves illiterate so that they would not question their position and desire a better life.
Douglass was soon sent away to another slave owner named Mr. Freeman. Mr. Freeman allowed Frederick to teach other slaves to read. Frederick taught over 40 slaves how to read passages from the New Testament. Other slave owners, however, became angry and destroyed the “congregation” in which Frederick taught. Four years later, in 1837, Frederick married a free Black woman named Anne Murray. They would have five children. He gained his own freedom by escaping from captivity by dressing as a sailor and boarding a train at Havre de Grace, Maryland near Baltimore. By the time he reached New York City he was free man (though not officially a free man). The trip took less than a day. Douglas continued to Massachusetts and soon joined the abolitionist cause. Inspired by the famous abolitionist William Lloyd Garrison, Douglass became an anti-slavery speaker and writer. At only 23 years of age, Douglas became a leading speaker for the cause and joined several movements including the American Anti-Slavery Society. He also supported the feminist cause and participated in the Seneca Falls Convention, a woman’s rights convention in 1848.
In 1845 Douglass authored Narrative of the Life of Frederick Douglass, an American Slave, an autobiography. The book was a critical success and became an instant best-seller. The book was translated into three languages and Douglas was invited to tour Ireland and Great Britain. Douglass spent two years in Europe lecturing on the horrors of slavery. Douglass became a popular figure in Great Britain, where his lectures were “standing-room only.” The people of Great Britain, roused by Douglass’ speeches, raised money on his behalf to pay his “owner,” Hugh Auld for his official freedom. Auld was paid 700 pounds by the people of Great Britain and Douglass was officially a free man in America.
When he returned to America, Douglas published the North Star and four other abolitionist newspapers under the motto “Right is of no Sex — Truth is of no Color — God is the Father of us all, and we are all brethren.” He advocated equal education for Black children, who received virtually no funding for education. As his reputation grew, Douglass became an advisor to Abraham Lincoln and Andrew Johnson. Douglass led a growing movement that caused a split in the Abolitionist movement. Douglass and others believed the U.S. Constitution was an anti-slavery document, while William Lloyd Garrison believed it was a pro-slavery document. In addition, Garrison believed that The North Star was competing for readers with his own newspaper, the National Anti-Slavery Standard.
By the time of the start of the Civil War, Douglass was one of the nation’s most prominent Black men. Later, the North Star was merged with other newspapers and was called the Frederick Douglass Paper. Douglass believed the primary cause of the Civil War was to liberate the slaves. After Lincoln issued the Emancipation Proclamation, Douglas continued in the fight for the rights of the freed slaves. After the assassination of President Lincoln, Douglas gave an impromptu speech at his memorial service. While Douglass’ speech mentioned Lincoln’s shortcomings in the fight against slavery, he gave Lincoln much credit for the liberation of the slaves, “Can any colored man, or any white man friendly to the freedom of all men, ever forget the night which followed the first day of January 1863, when the world was to see if Abraham Lincoln would prove to be as good as his word?” The speech was followed by a rousing standing ovation. It is said that Mary Lincoln was so moved by the speech that she gave Douglass Lincoln’s favorite walking stick.
After the war, Douglas was made president of the Freedman’s Bureau Savings Bank and several other diplomatic positions. During reconstruction, Douglass frequently gave speaking tours, particularly at colleges and universities in New England. In 1877, he purchased his final home, which he named Cedar Hill, in the Anacostia section of Washington D.C. Today, the estate is known as the Frederick Douglass National Historic Site. Frederick’s wife Anne Murray died in 1881, but he remarried Helen Pitts, a white abolitionist in 1884. Despite the controversy that their marriage created (she was White and twenty years younger than he,) the pair toured Europe in 1886 and 1887. In 1895, Douglass died of a heart attack at his home in Washington. |
Inside the CBCA Shortlist
Girl on Wire (Penguin Random House) is a highly metaphorical picture book, for older children, where a wire resembles a tightrope. It is a stunning work painted in oils, and the book cover resembles a painting canvas.
In the story an unnamed girl seems to be in a difficult or even threatening situation. She is anxious and fearful. Or, at the very least, she is simply avoiding a task or something she must do. She must take the first step, then continue along to move forward, change and grow.
Where is the girl? What could the wire or tightrope represent? What is hindering and helping her? How does she find courage?
The outstanding illustrations create changing perspectives and atmospheres. Consider how light and shadows are used, how movement is shown, and which part of the girl is focussed on at different times [e.g. feet, back view, from a distance, close-up].
Lucy Estela’s website is http://lucyestela.com/
Elise Hurst’s website is https://elisehurst.com/
Using the book with children:
Idiom What is another meaning of walking a tightrope? [a careful balancing act of thinking or acting when between difficult, changing or dangerous situations]
Motifs Birds and feathers aren’t mentioned in the written text but they are used as motifs in the story. Follow the birds and feathers in the illustrations. Examine how close and far they are from the girl. What is their role?
Read other books by Elise Hurst such as Imagine a City, Adelaide’s Secret World and The Night Garden; and Suri’s Wall by Lucy Estela, illustrated by Matt Ottley.
Balancing With safe monitoring, children could try balancing on something quite low to the ground (or on the ground) or walking along a balance beam (which could be a plank of wood) or low slackline. They could walk forwards and backwards; over obstacles e.g. beanbags; or through obstacles e.g. hoop. They could begin by looking at their feet and then look at someone in front of them as the girl does in the book. Is it easier to look down or at someone?
Tightrope Cartoons Children could use the online tool Toony Tools to make a cartoon of a character walking a tightrope https://www.toonytool.com/.
Tightrope Song Older children could listen to the song Tightrope, written by Pasek and Paul, sung by Michelle Williams, from The Greatest Showman movie. How do the lyrics relate to the picture book Girl on Wire? |
(Phys.org) -- Condensed-matter physicists the world over are in hot pursuit of a comprehensive understanding of high-temperature superconductivity, not just for its technological benefits but for the clues it holds to strongly correlated electron systems.
One important avenue of investigation is pairing symmetry. Its a property of Cooper pairs, the bound electron pairs that are a hallmark of all superconductors, whether high-temperature or conventional. The paired electrons act as if they were a single particle, and the energy required to break Cooper pairs is measured by the superconducting gap. The symmetry of the superconducting gap, known as the pairing symmetry, is an important characteristic of Cooper pairs that is intimately related to the mechanism of superconductivity.
In conventional superconductors, the Cooper pairs have s-wave pairing symmetry, which takes the shape of a sphere. In contrast, Cooper pairs in the cuprate family of high-temperature superconductors exhibit d-wave pairing symmetry, which looks a bit like a four-leaf clover. The leaves, or lobes, are areas where the superconducting gap is finite. At the points where two leaves join, known as nodes, the superconducting gap goes to zero.
However, iron-based superconductors do not fall nicely into either of these two categories. Some members of this group exhibit characteristics of superconducting gaps with s-wave pairing symmetry, while others show signatures of nodes where the gap becomes zero, as with d-wave pairing symmetry.
The key to resolving this discrepancy remained unknown until recently, when a team of scientists from Fudan University used an instrument at the Stanford Synchrotron Radiation Lightsource's Beam Line 5-4 to measure the detailed superconducting gap structure of the ferropnictide superconductor BaFe2(As0.7P0.3)2. They discovered a signature that could not have originated from a d-wave pairing a striking difference from the cuprate family.
This finding, the first measurement of its kind, provides solid experimental evidence that iron-based superconductors fall into the regime of s-wave pairing symmetry seen in conventional superconductors, and suggests that both nodal and nodeless gaps could arise from the same mechanism. This could lead to a unified theoretical framework for both phenomena, making the research an important step toward unveiling the mechanism of iron-based superconductivity.
Explore further: Physicists unlock nature of high-temperature superconductivity |
Plants can be engineered as living instruments, to provide farmers with valuable, timely and low-cost means to measure and monitor the status of their natural resources. This will provide new opportunities for empowering local choices about what to do with local crops, rather than bringing in crops and methods from elsewhere. Such engineering integrates the use of novel methods of molecular biology with the basic understanding of a field problem1 and a farmer-centered view about overcoming real challenges to sustainable, profitable crop production.
Sentinel plants, or bioindicators, have long been used in many agricultural systems to empower the farmer to make good decisions about land use, such as what to plant where and when to add expensive or labor-intensive inputs such as fertiliser, water and pesticides. A well-known example is the traditional planting of roses at row ends in vineyards. The roses show early symptoms of fungus that may affect the grape crop, therefore providing an early signal to the farmer to arrange for fungal control of the grapes, appropriate to the local soil, weather and consumer preference. A biosentinel can be any species that can grow on the land of interest concurrently with the crop of interest, or at the best decision time. It receives a signal from the environment and translates it in a way that is readily observable by people who can then decide what to do about it. The signal could even come from the crop itself: for example, leaves beginning to wilt signals that fruit set will be hurt unless there is more water.
To see more about patents and patent applications that cover the field of bioindicators or biosentinels, click here.
1 Jefferson, R.A. (1993) ‘Beyond model systems: New Strategies, Methods, and Mechanisms for Agricultural Research‘, Annals of the New York Academy of Sciences 700: 53-73
See presentation:”BiOSentinel Plants: Enabling Farmer Choice”. M.B. Connett Porceddu and R.A. Jefferson (2007) Hainan, China. |
Albert Einstein is not only acknowledged around the world as a genius but has practically become the symbol for genius in this century. His ideas encompassed our spiritual and social worlds as well as scientific and physical reality. He introduced a whole new paradigm of thinking that has affected many different areas of our lives. His discoveries in the field of theoretical physics made the “atomic age” possible and his humanitarianism has served as an example for the entire scientific community. His theory of relativity changed our entire conception of the universe and such basic aspects of our reality as time, space, matter and energy.
This book analyzes the thinking processes behind Einstein's unique personality and accomplishments. Using the cognitive modeling techniques of Neuro-Linguistic Programming the book explores and illuminates Einstein's mental strategies and beliefs.
The purpose of the study is to look beyond the specific content and scientific details of Einstein's thoughts to the cognitive ‘strategies of genius’ that created them. NLP provides a structure and a language to be able to put into a set of ‘chunks’ or steps the relevant mental processes used by Einstein. In this form, those mental processes can be transferred to others and applied in contexts other than physics.
By examining numerous quotations, excerpts from Einstein's own writings and anecdotes, the author paints a rich picture of Einstein's thinking processes and then shows how those thinking processes may be used by the reader to enhance his or her own creativity and problem solving ability.
This book is the second volume of a larger study on the Strategies of Genius. Volume I explored the creative process of Aristotle, Arthur Conan Doyle's Sherlock Holmes, Walt Disney and Wolfgang Amadeus Mozart. Future volumes include studies of Sigmund Freud, Leonardo da Vinci and others who have helped to shape our modern world |
The MV Nunavik made history last September when it traversed the fabled Northwest Passage without the help of an icebreaker. It was the first cargo ship ever to do so, but it likely won’t be the last.
As the climate warms over the next few decades, Arctic shipping routes will open more often, which could save significant amounts of time and money for both companies and countries.
UConn’s Scott Stephenson, assistant professor of geography, is charting the possibilities for the future of Arctic shipping lanes.
At this year’s meeting of the American Geophysical Union, Stephenson and Laurence Smith of the University of California Los Angeles, presented the scenarios for three potential routes through the Arctic: the Northern Sea route along the northern coast of Russia, the Northwest Passage through the Canadian Arctic, and the Trans-Polar Route over the North Pole.
The Northern Sea Route would cut travel time between Rotterdam and Yokohama by as much as 40 percent. The Northwest Passage and the Trans-Polar Route are attractive for similar reasons – if they are navigable.
To get an idea of which routes could be navigable by mid-century, the researchers ran shipping simulations for 10 well known climate models through the year 2060. They were surprised at how dramatically the models differed from each other – particularly because the models had agreed when they (accurately) predicted sea ice in the past.
The biggest surprise centered on the Northwest Passage. Two of the models showed it thawing earlier and more reliably than the Northern Sea route. Yet, currently the Northern Sea route opens earliest and most reliably. The Northwest Passage might be usable occasionally, but has a tendency to collect ice from other parts of the Arctic, clogging the narrow straits between the islands.
“Those models project more and thicker ice along the Eastern Arctic, which is not what we expected,” Stephenson says.
Eight of the models show the Northern Sea Route as the least costly route overall, favored by cargo ships from Rotterdam and Halifax to Asia sometime between 2011 and 2035, while two of the models show the Northwest Passage as the least costly. By 2060, a few of the models even show the great circle route over the North Pole becoming accessible for part of the year.
Maps showing potential shipping routes in 2011-2035 (left) and 2036-2060. Each line shows a potential route for a ship; the numbers associated with the color of each line are the average density of possible transits along that line over the 10 models. (Images courtesy of Scott Stephenson)
The Northwest Passage has captivated navigators since Europeans first encountered the New World, but sea ice and the complex geography of what is now the Canadian Arctic foiled them until recently.
The Norse, who explored Greenland and North America during a particularly warm period during the 11th century, got as far as Ellesmere Island. It took until 1903-1906 for Norwegian Roald Amundsen and his crew to be the first Europeans to make the passage. They traveled in a sloop that could handle shallow water.
Modern cargo ships need deep water, which limits their potential routes through the passage. The Nunavik draws 10.2 m (33 feet) of water, and is at the smaller end of the size range for cargo ships. As a polar class vessel, the Nunavik also has a fortified hull that can withstand up to 1.5 meters (5 feet) of ice traveling at 3 knots. In September 2014, she carried 23,000 tons of nickel ore from Deception Bay in northern Quebec to Bayuquan in China, completing the Northwest Passage from Port Deception to Alaska’s Point Barrow in just 11 days.
Currently most ships that enter the Arctic move similar cargo, ore, or oil that originates in the Arctic. That could change by mid-century, if the models run by the researchers prove accurate.
However, the costs of a route change depend on how many ports-of-call it contains. Cargo ships generally stop at several ports during a single run; the Arctic routes have fewer potential ports-of-call than the longer routes through either the Panama or Suez Canal.
One thing the models generally agreed on was the seasonality of Arctic shipping. In the early years, they showed that any navigation through the Arctic would need to take place between the months of July and October. But by 2060, ships with reinforced hulls like the Nunavik could have a season as long as nine months.
The researchers’ findings are also relevant to various governments that are keenly interested in Arctic navigation. Russia, Canada, Norway, the U.S., and Denmark all have territorial claims to land or waters in the Arctic. Canada, for example, claims the Northwest Passage as a Canadian waterway, while the U.S. and Russia insist it’s international. As access to the Arctic Ocean increases, additional claims over the Arctic seabed may arise. |
How Many Monarchs in Mexico?
Estimating the Size of the Overwintering Population
How Many Monarchs? Monarchs migrate to Mexico from across eastern North America. They cluster by the millions in 12 mountain sanctuaries. Because the butterflies are so concentrated, scientists can measure the size of the entire migratory population. How could they count so many butterflies?
Measuring the Area Covered With Monarchs It's impossible to count individual butterflies, so scientists measure the area of forest covered with monarchs. This picture shows a monarch colony from the air. The trees look orange because they are covered with butterflies. How large an area does this colony cover? Count the trees and estimate the area.
Identifying Trees in the Colony Scientists walk through the forest and decide which trees have enough butterflies to be considered part of the colony. They mark the edge of the colony with flagging tape.
Measuring the Perimeter of the Colony Next the scientists walk around the border of the colony and measure the distance between all of the marked trees. They must visit and measure all 12 of the monarch wintering sites. Their goal is to calculate the total area of forest covered with butterflies.
Measuring During Cold Temperatures The scientists always measure the colonies in December or January. This is the coldest time of year, when the monarchs form their tightest clusters.
Historic Population Data Population data have been collected consistently in Mexico since 1994. The graph shows the estimated area of forest the monarchs covered each winter. Look for trends. Why do you think it's valuable to collect population data every year?
is it important to collect and analyze monarch population data from
year to year?
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When embryonic cells get the signal to specialize the call can come quickly. Or it can arrive slowly. Now, new research from Rockefeller University suggests the speed at which a cell in an embryo receives that signal has an unexpected influence on that cell's fate. Until now, only concentration of the chemical signals was thought to matter in determining if the cell would become, for example, muscle, skin, brain or bone.
"It turns out that if ramped up slowly enough an otherwise potent signal elicits no response from the receiving cells. Meanwhile, a pulsing, on-off signal appears to have a stronger effect than a constant one," says researcher Ali Brivanlou, Robert and Harriet Heilbrunn Professor and head of the Laboratory of Molecular Vertebrate Embryology. This research is the latest collaboration between Brivanlou and Eric Siggia, Viola Ward Brinning and Elbert Calhoun Brinning Professor at Rockefeller's Center for Studies in Physics and Biology.
"Until now, it has not been feasible to test how speed or other temporal dynamics affect a cell's response to a signal. However, by adapting technology that allows for very precise control over these aspects, we found unequivocal evidence that signal level alone does not determine a cell's fate. Its presentation is also extremely important," Siggia says.
Together, the team dubbed their discovery "speed fating." Their work will be published in August in Developmental Cell.
Biologists know a cell determines its location in an embryo and, as a result, its future role, based on chemical cues from its neighbors. About 50 years ago, the developmental biologist Lewis Wolpert proposed that this determination hinges on the concentration of the signal to which a cell is exposed: Go above a certain threshold and you get one fate, below and you get a second. His proposal is known as the French flag model, after a tri-color graph used to represent three cell fates based on those cells' positions with respect to the source of the signal.
Prior work from Brivanlou and Siggia had cast doubt on the sole importance of concentration. Using a common developmental signaling pathway known as TGF-β, the team documented what is known as an adaptive response from cells exposed to TGF-β signaling molecules. This response peaked then declined over time, even though the signaling molecules remained present. (Think of how a constant noise eventually blends into the background.) If concentration was the sole factor responsible for a response, then the response should have continued as long as the signal was present.
To follow up on this work, Benoit Sorre, a former Rockefeller postdoc now at the University of Paris Diderot, adapted a system that makes use of miniaturized networks of pipes, pumps, valves and sample chambers all under computer control. For experiments, he teamed up with Aryeh Warmflash, the postdoc who lead the previous TGF-β work. Together, they worked with mouse cells that have the potential to differentiate into muscle, or cartilage and bone. Progenitor cells like these, which can differentiate into a limited set of tissues, are the offspring of stem cells. In experiments using Sorre's new system, the researchers exposed these progenitor cells to signaling molecules from the TGF-β pathway, and then recorded the cells' responses to see if the signal activated the pathway that leads them to choose a fate.
Sorre and Warmflash started with a continuous signal. As Warmflash's previous work suggested, this finger-stuck-on-the-buzzer approach did not produce a continuous response from the cells. Instead, the response declined. A second set of tests showed a series of brief pulses of signal produced a greater response than one continuous signal.
Gradually increasing the concentration of the signal, however, appeared to have the opposite effect. The researchers ramped up the concentration of the signal over periods as brief as five hours or as long as 40 hours. The longer the period and the slower the rate of increase, the weaker the cells' response. The cells subjected to a 40-hour run barely registered at all.
Based on these experiments, the team formulated a mathematical model to describe how a cell in an embryo may infer its position in relation to the source of the signal. In this way, the research offers a new take on the French flag model: It is still true that the fates of three cells can be mapped out based on their position, but the cells appear to arrive at these fates more rapidly than previously thought, thanks to the adaptive response that takes into account both the level and speed of a signal.
"This finding is another instance of a productive collaboration between biologists and physicists. Neither group, biologists or physicists, could have realized this result working alone," Siggia says. |
The Roman Army
The Roman army was one of the finest fighting machines the world has ever known. Beginning as a group of citizen soldiers who provided their own arms and defended the early city of Rome in times of emergency, the Roman army grew to become one of the largest professional fighting forces the world had ever seen. In later years, the enormous bureaucracy that governed and supplied the Roman army would grow to rival those of modern days. During its 1,200 year existence in the West and 2,200 year history through Byzantine times, this army underwent numerous major transformations and smaller changes. Some changes were brought about by new advances in weapons, some because more effective tactics were developed, and some occurred because the pressing needs of the empire required change. One change that continued right up through the end was the increasing use of barbarian troops and officers. In the years before the end of the Roman Empire in the West, the army was composed of almost all barbarian troops who were defending an increasingly weak empire against their own relatives. If there was ever a conflict of interest, this surely would be one!
The legion was the largest unit in the Roman Army. Originally, a legion consisted of from 5000 to 5500 men, but seldom was a legion ever at its full strength. More often, a legion consisted of 4000 to 4800 combat ready troops.
Each legion was divided into cohorts of about 600 men each. Sometimes the number one cohort was twice the size of the others. The number one cohort was usually assigned to administrative and supply duties.
The basic battlefield unit was the century, originally composed of 100 men. This Latin word means a unit of one hundred and it is the same word we use today for a unit of one hundred years. Most legions had less than the full number of troops and usually contained between eighty and one hundred men, and sometimes even less than that. They were led by a non-commissioned officer called a centurion. There were different grades of centurions. Some were men who had only been in the army a few years and whose rank was roughly equivalent to a sergeant. Others were twenty year or more veterans and might be likened to a commissioned or staff officer in today's United States or British army.
Another unit that appeared from time to time was the maniple. A maniple consisted of two centuries, giving a cohort of three maniples or six centuries.
During the Third Century, the emperor Gallienus introduced a fast, mobile striking force mounted on horseback. Before this time, Roman officers and soldiers sometimes rode horses to the scene of the battle but dismounted to fight. Gallienus' troops were real cavalry in that they fought from horseback as well.
Diocletian and Constantine officially divided the Roman army into the COMITATENSIS, or mobile fighting force, and the LIMITANEI or troops assigned to guard the frontier. This pattern was kept and maintained until the end of the Western Roman Empire. The idea behind the COMITATENSIS was to have a highly mobile field army that could be ready to go anywhere in the empire at a moment's notice and be on the scene of trouble in two to three weeks.
Auxiliary units began to be used more and more from the reign Of Septimius Severus in the early Third Century onward. These included lightly armed cavalry "wings", units of mounted archers (SAGITTARII), lancers, heavily armored cavalry (CATAPHRACTII), and other specialized units. Julius Caesar used skilled slingers from the Balearic Islands and Batavii (from near modern Belgium) who were strong swimmers and could withstand cold water. They made excellent special agents and infiltrators. Roman army organization, tactics, and strategy is the subject of countless books. The Roman Army still holds the fascination of military historians today, as more books are being written all the time as they have for over two thousand years.
Starvation was a very common strategy used in the ancient and medieval worlds to bring an otherwise strongly defended city or fort to the point of surrender. The besieging army would surround the city, cutting off all routes whereby it might be resupplied with food and water. If the king or other ruler who governed the city planned ahead, the defenders could bring livestock and supplies of grain within the walls. Often cities were built so that a spring or good well was enclosed within the walls. In these cases, the besieging army would have a difficult time starving the city into surrender. The Romans had a few other tricks up their sleeves when confronted by a stoutly defended and well supplied city. They built siege towers from wooden poles bound together with leather from the top of which they could rain arrows down on the unfortunate defenders. They also used siege artillery such as ballistas, onagers, and catapults to throw stones or short, thick arrows known as bolts over the walls at the defenders. The Romans were not above using some dirty tricks, too. balls of flaming pitch and burning sulfur were used by both attackers and defenders. Sometimes, the besiegers would cut the heads off slain soldiers who were known to be relatives of those holding out behind the walls. The severed heads were allowed to ripen in the hot sun until they had reached a very smelly and offensive condition. They were then pitched over the walls with catapults to fall amongst the hapless population of the besieged city. Another tactic used to terrorize and demoralize the population of a besieged town over a period of days or weeks was to mount the heads on pikes. These trophies were then set up in full view of the defenders and allowed to stay there until they became black and leathery. To add to the discomfort of the people holed up behind the walls, the besieging troops often made these heads of the defenders' former family members the object of scorn and desecration.
Pulled by specially bred horses, chariots like the one shown on this coin served the Romans as "mechanized infantry" and provided a fast, reasonably well armoured platform for mobile archery strikes. They had been used by much earlier civilizations including the Assyrians, Hittites, and Egyptians who employed them in war and also as a suitably triumphant looking conveyance for their rulers while on parade before their people. Chariots and the horses that pulled them also served as a psychological weapon, striking fear into the hearts of enemy soldiers. Ancient chariots were attached to a type of harness that forced the horse to pull with his neck rather than his shoulder as is the case with modern harness. This was injurious to the horse, often choking the animal and certainly reducing the weight of load he could have pulled had he been fitted with a better collar. It has been speculated that the reason so many horses depicted in ancient art are shown in the act of rearing up and pawing the air with their front hooves is that they were reacting against the harness rather than displaying their bellicose fierceness and raw animal power!
The onager, meaning "wild ass" in Latin, was the name given to the small Roman catapult used for hurling medium sized stones at enemy troops and over the walls of fortified towns. Like the ballista and the large siege catapult, the onager was powered by a spring made of a combination of twisted leather thongs and heavy arms made of springy wood or bone layered with wood. The operator would use a pole in a windlass to wind up the onager, which had a ratchet so that the soldier operating it could move the pole to another socket in the windlass. When the trigger mechanism was released, the wound up spring would swing up a long arm at the end of which was a basket holding a good sized stone. The secret of how the Romans were able to make such good springs from hide and bone from animals and wood from trees has been lost. Some historians who have investigated the scientific discoveries of the ancient world believe that the Greeks had developed a springy alloy of bronze unlike the spring bronze used in some machine parts today, but it was only used in experimental catapults. There is no evidence that the Romans utilized metal springs in any of their siege engines.
Like any modern army the Romans had their main body of infantry troops and also their auxiliary troops, their cavalry and mounted infantry, their bush fighters, and their desert warriors.
Regular deductions were made from the legionary's pay to cover normal wear and replacement of his equipment, similar to the deductions made for his burial expenses and the annual camp dinner. In the case of nail money the situation was reversed and the soldier was given an allowance for worn boots.
Beginning with the soldier's basic equipment, we have:
Steel or Bronze Pot Helmet (Cassis). Junior officers (Optiones) and Centurions might wear protective headgear almost as highly decorated as they could afford to purchase. Most infantrymen used the stock issue helmet provided by the quartermaster's department.
Segmented Plate Cuirass and Body Armour given the name Lorica Segmentata by modern historians, those formed of steel plate armour was riveted together securely enough to withstand sword slashes yet with enough play between the plates that the armour would flex when the legionary moved about. This type of armour was much less expensive to fabricate than the fine chain mail that was more popular amongst the legions in the East.
The Long Curved Rectangular Shield or Scutum is probably one of the most variable of the equipment items carried by Roman legionaries throughout the 1100 year existence of the Roman army in the West and the 1000 additional years during which Romaion or Byzantine military tradition held in the East. During the last century of the Republic and the first century of the Empire, the scutum was in general use. Even so many units preferred either a large or a small round shield, and oval shields became popular during the later Roman Empire (AD 330 to 600). One advantage of this type is that they could be held edge to edge to form a Testudo, which provided armoured protection with good coverage for a group of men.
Leather walking sandals These did not change much during the course of historical antiquity. Their open design permitted the feet to breathe on long marches. They were relatively easy to make and repair, unlike the formed leather boots adopted by European armies much later. It was the excessive wear caused by so much forced marching that led the mutinous legions to demand nail money upon the accession of the Emperor Tiberius. The money would ostensibly be used to replace the worn out sandals.
The long red military cloak kept the legionary warm in colder climates and helped keep the rain off during inclement weather. Its red colour was also probably intended to identify him as a Roman in the dust and confusion of battle and inspire fear into the hearts of his enemies. The sight of a massive red juggernaut headed relentlessly in their direction must have clamped a cold claw of fear around the heart of many defenders of rebellious cities and sapped their will to fight.
Short thrusting Sword (Gladius) Roman battle tactics called for close - ordered, disciplined troops fighting as a team as opposed to individual heroics as used by many of their enemies. There were no heroes or champions in Roman armies, only trained soldiers, standing shoulder to shoulder for twenty minutes at a time, methodically killing their opponents. When an occasional lucky stroke by a barbarian warrior brought down a Roman soldier, another of his brethren immediately stepped forward to fill his spot. When the twenty minute period of killing was finished, the legionary fell back and rested to be replaced with a fresh man.
These kinds of tactics called for a short thrusting sword instead of the long one used for slashing. The Roman Gladius was 18 to 24 inches in length, double edged and parallel sided. The last few inches of blade tapered to a point and the grip was terminated on the back side with a large ball shaped pommel. A short, powerful thrust going a few inches into a man was much more deadly, though less dramatic, than the wide, energy wasting slashes made by an individual warrior showboating in front of his buddies.
Medium length Throwing Spear or Javelin (Pilum) This is another standard weapon that almost defines the Roman legionary. The medium weight iron head was connected by a long, thin neck to either an iron socket into which the wooden shaft was fitted, or the metal was extended backward into a thin tang which fitted into a socket in the wood. The main point is that the hardened head of the Pilum would penetrate the enemy shield and the soft neck would bend over. Removing the head of the Pilum from the shield would take too much time, so both Pilum and shield were then thrown away. At this point, the enemy warrior had only two and a half choices left: he could turn around and run like a rabbit, hoping that a Roman scouting party was not waiting for him to do just that. He could let out a bloodcurdling scream and go berserk like the Vikings much later and run up and try to brain one or two Romans with his sword before being skewered himself. In this case, maybe his buddies would sing sagas about him around the campfire on cold Winter evenings, telling of his brave deeds while the Romans celebrated Saturnalia in their camp, laughing about what a numb skull he was. Choice number two and a half is he could look around the battlefield for a shield not pierced by a Pilum, perhaps dropped or thrown away by one of his buddies. He could pick it up and dust it off, and walk coldly and deliberately towards the Roman lines. He could then kill two Roman soldiers, one for his fallen/fleeing buddy, and one for himself, to make up for the embarrassment of letting him get close enough to a Pilum equipped Roman soldier to get his shield pierced.
Long before modern military engineers came upon the idea of using armored vehicles to protect soldiers from enemy fire, the Romans had developed armored divisions of their own. When attacking a fortified town or a heavily defended enemy position, the Roman legionaries would arrange their shields to form a box covering their heads and all sides. This tactic was called the Tetstudo, meaning tortoise in Latin. They could then advance through a hail of arrows or sling stones to overrun the enemy in his position. Moving the shields apart just enough to allow their swords to poke through, the Romans used the same stabbing technique that they found so effective in regular battle. Because they did not slash with their swords but would thrust and stab, they did not have to leave much of a space in their shield wall. It must have been a fearsome sight indeed for native warriors in Gaul or Persia or northern Thrace who were not used to the cooperation of disciplined warfare and preferred individual heroics. It was not until the coming of heavy mounted cavalry and well designed saddles with stirrups that an effective way was found to attack the Testudo.
The Earliest Army
The earliest Roman army is usually described as composed of about 1,000 men per tribe drawn in 100 man levies. The soldiers were armed as Greek Hoplites and fought in a simple Phalanx.
The 4,000 MAN Five Class Army
Tradition attributes the reorganization of the army to the sixth king, Servius Tullius, although the actual process may have taken a number of years. By the time of the war with Veii the army probably had fully developed the 5 classes. Without detailed descriptions of the army formed from the classes one can only make reasonable guesses about its composition. In this model the same number of men are assumed to have been levied from each Century, the phalanx is kept at the Greek standard of 8 ranks, and the overall army size is about 4,000. If 25 men from each Century were levied then there would have been 2,000 from the First Class, 500 from Classes II through IIII and 750 from Class V. 4,000 men in 8 Ranks will fill 500 Files. That would give the First Class 4 Ranks, Classes II through IIII one Rank each and leave 750 men in Class V for the 500 files of the last Rank. The last Rank is represented as composed of 500 men of the Fifth Class with the remaining 250 men being used as skirmishers, flankers or camp guards. In the drawing this presumed 250 man unit is not depicted. Although barely visible at this scale, the Phalanx in the drawing above is divided into separate ranks by Class. Each Class is given a different colour. Under the assumption that the Phalanx would have been somehow subdivided into smaller units, the 500 files have been divided into units of 100 files 8 ranks deep and separated by three meters (ten feet) to provide room for the phalanx to manoeuvre. Of course, the actual armies were never so nicely composed, but this configuration at least gives a reasonable starting point for visualizing the army.
The Early Livy Legion
The earliest legion is generally said to be the 45 unit legion as described by Livy and dates to the early part of the 4th century BC. The maniple consisted of two centuries of 10 files by 3 ranks. All maniples had the same number of men. In front of each Hastati maniple there were 20 skirmishers called Leves. All maniples were armed with the spear and oval shield.
An Alternative Early Legion
Delbrück offers an alternate interpretation of the Livy legion, different from Connolly in his analysis of the Rorarii and Accensi. He works from Livy's number: 186 men "antipilani" and "sub signis." His explanation is that the Triarii were at one time called the Pilani and that the Triarii, Rorarii and Accensi were positioned behind the standards. Those behind the standards, then, were the 60 men of the Triarii; plus the 120 Rorarii attached in units of 40 men to each of the Hastati, Principes and Triarii maniples; plus the 6 Accensi, orderlies or company clerks; for a total of 186 men. He considers the Leves, the skirmishers, to be a part of the 40 man Rorarii unit assigned to each Hastati maniple. For the 10 Hastati maniples that would place some 200 skirmishers directly in front of the battle line. These are the men who would retreat through the gaps in the Hastati line. He also mentions that there may have been other skirmishers on the flanks; possibly the other 20 Rorarii of the Hastati maniples. He does not believe the Rorarii of the Principes and Triarii maniples were combat soldiers at all, but rather were unarmed assistants. The Accensi, he says, were totally misinterpreted by Livy. These were the 6 orderlies of the cohort. In muster formation the three 40 man Rorarii units would stand behind the 60 man Triarii maniples. Behind them would stand the 6 Accensi orderlies. This gives the number of 186 men as "sub Signis."
Delbrück argues against the notion that the legion actually went into battle with wide gaps between the maniples. His view is that the legion was really an articulated Phalanx with only small intervals between the maniples to allow adjustments in spacing due to irregular terrain and errors in marching. The gaps would be naturally closed by the men in the adjoining maniples at the time contact is made. If larger gaps opened whole units such as centuries or maniples of the Principes would fill in. The maniples of the Principes would have lined up on the small intervals in the Hastati. The Delbrück maniple has men on 0.91m (3') spacing both for file and rank with the centuries placed side by side. Each century has 10 files and 6 ranks. The placement of the centurions is not given. Delbrück recognizes the requirement for 1.83m (6') of fighting room for each individual given by Vegetius. However he interprets the 1.83m (6') spacing as being between adjacent ranks, not files. His method is to have alternate ranks step to the side to fill in the gaps in the rank in front. In this way there is 1.83m (6') between rank 1 and rank 3 The Delbrück maniple in battle formation had a staggered formation.
Twenty men from each Rorarii unit attached to the Hastati are depicted as skirmishers spread in a thin line in front of the legion. They would retreat through the narrow gaps between the maniples. The other twenty men of the Hastati Rorarii units may have been used as skirmishers on the flanks; they are not depicted in the schematic. The balance of the Rorarii and Accensii are placed at the bottom of the schematic to indicate that they were, in Delbrück's reconstruction, not a part of the battle and may have been left as camp guards. The Triarii maniples are comprised of two 30 man centuries aligned one behind to other to maintain a 6 Rank depth. Delbrück states that a depth of fewer than 6 Ranks would not have been an effective force and that the maniples could make up for the gap because of the distance they had between themselves and the battle lines would allow them time and space to maneuver to close the gaps if necessary.
Delbrück does not specify how wide the small gaps between maniples were, but he does allow enough for the 20 skirmishers to retreat. The model uses a spacing between maniples of 3.05m (10') which seems large enough to allow the 20 skirmishers room to retreat and small enough for a few men on either side to close the gap. Delbrück also argues that the 76m (250') spacing of the later legions is an echelon tactic introduced first by Hannibal and adopted into the Roman system by Scipio Africanus, sometime between 211 and 200 BC, probably in Spain. Prior to his innovation the three lines, Delbrück believes, would have been fairly close together, about 30m (100').
The 4,200-man Republican Legion
At some time after 340 BC the legion was reorganized again. It may have been about this time that 200 of the Rorarii were withdrawn, trained, armed as light skirmishers and named Velites. From this time the legion was configured with the standard 30 maniple formation. The maniple was comprised of two 60 man centuries, usually described as either 10 files by 6 Ranks or 12 files by 5 Ranks. The latter formation is used in this schematic, following Rüstow and others. In this version of the legion the large Velites units are shown aligned between the two centuries of the Triarii in the third line as they would have been during muster and, perhaps, during battle after they had retired. The centuries of the Hastati and Principes are shown aligned one behind the other. This is the classic formation as it is usually given, by Montross and Rüstow, for example.
Delbrück credits the development of echelon tactics to Scipio Africanus, probably during his campaigns in Spain. The great advantage of echelon tactics is that it allowed the lines to operate somewhat independently. He also places the introduction of the Pilum to coincide with the new tactics. The legion of Scipio is essentially the same as the earlier legion in its overall formation with the exception that the lines are much further apart, about 76m (250'). In this schematic the Velites are shown in the skirmish position.
The 4,800-man Legion of Marius -- Cohort Tactics
A major change came at the time of Marius and is usually attributed to him, although some elements of the reorganization of the legion may have been implemented prior to Marius' reform. The nominal maniple strength was probably 160 men, divided into two centuries which most authors place one behind the other. The most likely configuration is 16 files by 10 ranks. It has the advantage of scaling down by units of 5 or ten as the maniple strength was depleted. By the time of Caesar it is clear that the cohort had become the fundamental tactical unit. He describes battle formations and troop movements in terms of cohorts and legions appear more as administrative units than battlefield tactical units. Caesar sends cohorts and groups of cohorts, not legions, on flanking manoeuvres. Since the number of men in a cohort could vary considerably the formation must have been scaleable in some consistent manner so that its fighting efficiency was not destroyed by the reduction in manpower. The typical formation, described above, uses a spacing of 0.91m (3') for the files and 1.22m (4') for the ranks; allowing for the centurion, then, the cohort would have a front of 15.85m (52'). If the three cohorts fought side by side, as is always depicted, then their combined front would have extended to 48.16m (158'). The cohort would, in essence, be a miniature phalanx, 10 ranks deep and 58 files wide.
Caesar's legions are usually described as having a strength of about 3,600 men, fewer than the full strength legion. How would the under strength legion have been configured? It seems reasonable that the cohort would be scaled down by reducing the number of files, not the number of ranks. Reducing the number of ranks would decrease the depth and hence the power of the formation. Reducing the number of files would reduce the front but retain the full power of the formation. It therefore seems most logical to retain the full 10 ranks as the depth and reduce the number of files as necessary. The drawing on the right shows two reduced centuries of 5 ranks and 12 files each. At the battle of Ilerda Caesar's forces were caught on a narrow ridge just wide enough for three cohorts in line of battle. Judson states that this ridge can could be identified in his day and was 110 meters (360') wide. The front of a 12 file cohort is 12.2m (40'), giving a three-cohort unit a front of exactly 109.73m (360'). If Judson's information is correct, it would appear to confirm this formation.
The Legion of Marius -- Alternate Formations
Delbrück does not specifically discuss the question of gaps between the cohorts of the Marian legion. He argues, persuasively I think, against the possibility of gaps in the pre-Marian legion formation in which the units and, consequently, the gaps were much smaller. To be consistent Delbrück would have to be presumed to eliminate the wider gaps in the post-Marian legion, placing the cohorts close together with only small gaps between them. The drawing below shows this legion with 7.62m (25') spaces between the cohorts for the skirmishers. The legion formation in this configuration is much more compact and has a front of only 212m (694'). If this were the legion formation then it would be a departure from the earlier legion in that the centuries would now be aligned front to back rather than side by side. In favour of this configuration are: (1) the cohort front fits Judson's information about Ilerda (assuming Judson is accurate), (2) the second century was called the posterior century, and (3) since cohorts were used as quasi-independent tactical units they may have needed the extra depth of the formation.
Against this configuration is the argument for consistency and conservatism. It can be argued that, if the centuries were aligned side by side prior to the reorganization of Marius, then it seems likely that they would have been aligned that way after Marius. The change in the position of the Posterior Century would represent a significant change in tactics, even down to details such as how and when the ranks could employ their pila. The style of fighting had evolved over a long period and may be considered to have been "optimized." That is, the tactics of the individual soldiers armed with the scutum, pilum and gladius which had been evolved to this time were probably those which best suited those weapons; major changes would probably not have been an improvement. Finally, at the level of the century, the soldiers were trained, drilled and led by their centurions who represented a conservative, in the sense "conserving," element in the army; Marius' changes were dramatic enough without also including fundamental changes in tactics at every level and the re-training which would have had to occur. If the centuries were arranged side by side to form an unbroken line, the drawing above shows how this formation may have looked, with 1.53m (5') spaces between maniples and 6.1m (20') spaces between the cohorts. It gives an overall front of 391m (1,282').
The 5,130-man Imperial Legion
During the second half of the first century AD, the size of the cohorts was increased. The regular cohort was increased in size to 480 men in six centuries of 10 files and 8 ranks each. The first cohort was enlarged to 810 men in 5 centuries of 18 files and 9 ranks. The centuries are usually represented as being arranged two deep with the maniples side by side. For the six centuries of the normal cohort this is a logical formation. For the five centuries of the first cohort the scheme does not work. If four of the centuries are aligned in a rectangle they occupy about the same space as the six centuries of the other cohorts. This would allow them to fit nicely into the overall legion formation. That would leave one extra century. An alternate formation is possible. If the legion did close gaps by aligning the maniples side by side within the cohorts to form a continuous line, then the formation may have looked something like the drawing below. The legion was a fighting unit with unique weapons, tactics and formations; and was the most successful army of the ancient world. Yet we do not understand how it functioned in some of the most basic ways. The legion's formation and tactics were changed over time and were adapted to meet local battlefield conditions. Yet there is a core understanding, an "idealized legion," which can be described. The legion incorporated its own unique characteristics; among them were: the regular use of two and three lines, division of forces into centuries, maniples and cohorts, command by Centurions, use of trumpets and standards, and the tactics of the Pilum and Gladius.
Cadence of the march and run
The march cadence is fairly well established. The Roman militari gradu, regular march cadence, was 100 paces per minute, the quick march cadence was 120 paces per minute. The Roman foot was 0.9708 English foot. The pace was 2.5 Roman feet, 29.124". According to Upton, this is almost exactly the same as the US Army standard at the turn of the century; its pace was 30", the regular march cadence was 100 paces / minute and the quick march cadence was 120 paces / minute. The pace of the running charge is unknown, and surely varied considerably from battle to battle according to the terrain. The running pace used in the model was derived from some modern data from a variety of sources. A "pace" is the interval between left and right heel strikes, a "step" is the interval between strikes of the same foot. There are two paces to the step. The Roman soldier was running in formation, over uneven ground, carrying arms, wearing armour, and in the process both throwing his pilum and avoiding oncoming missiles. For modelling purposes I used 3 paces of 40" per second for the charge, less than runners in even long distance races but faster than a jog.
The next element to work out where in the attack the pila might have been thrown by each rank. Authors give a wide range of distances for the pilum, from a high of 27.43m (90’) to a low 7.62m (25’). One even puts it as low as 4.87m (16’) but this seems wholly unreasonable. The estimated weight of the pilum also varies widely. One author estimates the weight at 8.62kg (19 Lb.), another at 4.99kg (11 Lb.). Spears and pikes in museums, of similar length but different construction, weight between 1.59kg (3.5Lbs.) to 2.5kg (5.5 Lb.). Calculations based on an accurately drawn model and using typical densities for iron and wood give a weight of about 4.9 pounds. The weight added to imperial pila probably doubled the overall weight. Although some authors say that a throwing strap was used, most disagree. The soldier used his pilum during the last few seconds of the charge while running over uneven ground, keeping his spacing with his comrades, and dodging enemy missiles. Furthermore, he had to be able draw his sword immediately upon release or upon dropping the pilum. A throwing strap would seem like an unwelcome and even dangerous encumbrance. The model is based on the use of the pilum without a throwing strap.
Over the centuries of its existence the Roman army used a variety of cavalry support units. The early legions were supported by 300 horse formed into a unit called the Ala. In the latter years of the Republic Caesar, for example, employed thousands of allied cavalry. At times, during the empire the role of the cavalry at times diminished to a few hundred support units. This page is not an attempt to describe these cavalry units in detail but is only intended to give a general view of the cavalry units and their sizes relative to the army as a whole. The basic cavalry soldier was almost always armed with a shield and stabbing spear, supplemented by a sword. The Romans were never noted for using mounted archers, for example. The appearance of the cavalry soldier would surely have changed over time.
The Roman roads were constructed for military purposes. It is obvious that, whenever possible, the army moved along the roads. Therefore the width of the paved roads determined the width of the Roman column. Most descriptions ignore this factor. Judson, for example, describes the army marching on a 40 foot front. There were no Roman roads that were 40' wide. However, most descriptions of the army on the march state that the soldiers marched 6 abreast. The standard spacing is usually given at 3' for each file. Allowing 1 foot between the edge of the road and the lane in which the outside soldier marches requires a minimum road width of 18 feet. This 18' road width is drawn in red in the illustration. The top set of blue figures show a rank of 6 soldiers on 3' intervals and how they would fit into the road widths. The lower set of figures squeezes the 6 men into a width that would fit the Via Appia when it was repaved, 14 1/2 feet. This formation does not seem viable to me in that the actual width of each man, including his gear is 2'6" and the allowed width for each file is 2'7". There is only 3" between the outside man's foot and the edge of the road. It does not seem feasible that six men could march with their gear in that tight a formation. The conclusion is that the standard description of 6 abreast only works on certain road surfaces. On many roads, some of which were as narrow as 5 1/2 feet, the number of files would have to be reduced and the length of the column extended accordingly. During the era of conquest the Roman armies ventured into new territory that did not have the fine Roman road system. I have no information about the conditions of those roads but can only assume that they were inferior to the Roman roads, probably more like tracks in many cases. The tidy arrangement of ranks and files and marching units would hardly be appropriate when visualizing the army moving under those circumstances.
Horses, Mules, Oxen, Carts and Wagons
The baggage train took up most of the marching column. A few introductory words about how the Romans transported their baggage is in order. The Romans had no large draft horses, nor had the horse harness been invented. The yoke system that was developed for oxen was poorly suited for horses. Horses were generally used only to pull light two wheeled carts. Heavy wagons were pulled by oxen. Ancient wagons were designed to be pulled by two animals. Horses and mules can travel at about the same speed as a man, 3 to 4 miles per hours. Oxen travel only about 1 mile per hour. The preferred method of transport was by pack mule. Several different mule packs are represented in the illustrations for the march. The pack for the mule carrying the contubernium's tent and equipment is loosely modelled on a photo of a modern re-enactment group. The other loads are imaginary. However it seems useful to make them look different to underscore the fact that there would have been quite different loads for different parts of the baggage train. Including different packs in the illustrations encourages thinking about the great variety of material that the army needed to take with it.
Roman armies came in many variations over the centuries. For most of the republic the 4 legion army was standard, during the late republic armies became much larger. Under the empire many of the legions became less mobile, serving more as static border guards than as mobile armies. In the late empire the entire army structure changed with much greater weight being placed on the cavalry units. The types and numbers of light infantry (skirmishers) changed over the centuries. The early legions used velites from the legion itself as skirmishers, later armies employed auxiliary skirmishers. The cavalry also changed. The early legions had a small contingent of Roman and allied cavalry, later the cavalry consisted almost exclusively of auxiliaries. Under empire there were periods where there was not much cavalry associated with the armies and then, later, when cavalry took on a much greater role.
Throughout the centuries it seems that the basic unit of the Roman army was the contubernium, the tent mates. There is ambiguity and disagreement among the sources about the number of men that made up a contubernium. Some consider the contubernium to have consisted of 8 soldiers, others 10, with 2 on watch. What does seem clear is that only 8 men could sleep in the standard 10' by 10' tent. The discrepancies are in whether the tent-unit included 10 men with two always on watch or was just 8 men. The elements of the contubernium are: 10 soldiers, 1 10' by 10' tent, 1 mule and 1 servant. The mule is cared for and led by the servant (calo). The tents poles and stakes are estimated to weigh 40 pounds. The maximum load for a pack animal was estimated at 200 pounds but one was assigned to each tent to carry the extra food, baskets for excavating trenches, a handmill to grind grain, and a variety of other tools and equipment. The pack includes a folded tent, the tent poles, two large baskets on either side filled with tools and cooking utensils, and a sack of grain.
Each centurion is assigned his own tent, a mule and a servant. The centurion's tent was 10' by 10'. Each officer is assigned one mule to carry the tent and their personal gear. The mules packs are different from that of the contubernium since there are no entrenching tools used.
Optio: The optio may or may not have had a tent.
All authors agree that 8 men could sleep in the contubernium tent and modern reenactors confirm this. On this basis, 1 tent is assigned to each 8 servants since none of them would have been on watch. In most cases I allotted 1 tent to each 8 servants, but where there were 9 or 10 in a unit, rather than add a tent for one or two people, I crowded the extra servants into the one tent. The pack mule for the servants is again slightly different from that for the contubernium. It lacks the baskets and entrenching tools but has some additional cooking utensils. The tent represented is the same size as that for the contubernium.
The size of the century varied from time to time in the history of the legion. There were noticeable differences between actual and theoretical legion strength as well. For the purpose of the models I have considered the century to be 80 men: 8 contubernia, 1 centurion, a signifer and an aeneator (either a cornicen or a tubicen).
The Maniple and Cohort
Two centuries made one maniple and three maniples made up one cohort. The two centuries of the maniple have 10' between them, as do their respective baggage trains. There is 20' between each maniple. The borders of the three maniples are colored, top to bottom, blue, red and green to help distinguish them.
Ten cohorts make up one legion. The ten cohorts take 3,726 feet in the column of march, the baggage train for the legion is nearly as long, 3,580 feet.
The Decuria, Turma and Ala
The number of Roman cavalry assigned to the legions varied over time but an early standard seems to have been 330 to the legion organized into a unit called the ala (wing). It was comprised of ten turmae. Each turma consisted of three decuriae of 10 soldiers and an officer called a decurio.
Pack train: Each decuria has one tent for its ten soldiers and one for its officer. One additional tent is added for the servants, making a pack train of 7 animals for each turma. The turmae which did march in a battle-ready condition would need pack mules for their personal gear. The ten turmae would not have marched in this formation since they used to scout in advance, guard the flanks and read and guard officers and important baggage. I show the distribution of the Roman cavalry forces later in conjunction with the auxiliary cavalry.
Each legion had 6 tribunes who served as officers to the legate. They are shown in the illustration on the left with their baggage train. Each tribune has a tent, a personal pack mule and one extra horse that is led by a servant. Three tents are required for their servants.
Each legion was under the command of a legatus. The legate is assigned a large tent that requires two mules to carry, 4 personal pack mules, and extra horse. There is one tent for the servants.
The signiferi are always mentioned but there is seldom a specific allowance made for them when the army is described. For example, the usual descriptions do not mention tent locations in the camp or baggage requirements. The first rank has four signiferi in it. They represent the signiferi of the legion proper are left to right, an aquilifer, imaginifer, draconarius and an old style signifer carrying a taurus, bull, standard. Following them are the 60 signiferi for the centuries. Then come four vexillarii for the four centuries of antisignani and finally three mounted signiferi: a vexillarius for the legion itself (shown mounted because he accompanies the legate), a vexillarius for the Roman ala, and a draconarius for the ala.
Aeneator is the generic name for the soldiers who carried the signaling horns. Just like the signiferi, the aeneatores did not march together but were disbursed throughout the legion. The usual numbers for a legion, are: one cornicen is assigned to the first century and one tubicen to the second; 30 each per legion plus 3 of each to the cavalry units, 1 tubicen to the legate in command of the legion and 1 tubicen to the first tribune. One bucinator to each cohort, 1 to the cavalry and 1 to the legate in command.
In the earliest legions the skirmishers were the velites attached to the third line. In later legions they consisted of auxiliary units of specialists, mostly slingers and archers. The trains are long for several reasons. The skirmishers were used as advance scouts during the march. Because of the nature of their weapons (lead shot or stones, bows and arrows ) they would require some additional supply. Four mules, one for each 20 skirmishers, have been assigned for this purpose. If these soldiers were on active duty as light fast infantry they would not have carried their own gear, as did the legionaries. Since the load for one man is usually set at 40 pounds, one mule for each 5 men has been assigned for personal gear. this makes for a considerable pack train, a total of 33 mules per century to carry the tents, gear and servants tents.
In addition the legion would have scribes to keep its records and accounts. I arbitrarily assigned 16 to the legion: 1 for each of the 10 cohorts, 1 for the ala, 1 for the fabri, 1 to keep the supply accounts, 1 as an overall paymaster and role keeper, 1 to the tribunes and1 to the legate. The scribes were probably slaves. The pack train is very large because the scribes kept the records of the legion and would have had bulky sets of scrolls, blanks scrolls, writing supplies and writing desks. They may even have had charge of pay chests. Because the scribes would have needed a place to work out of the weather it seems reasonable to assign each a tent of his own to protect his records and be his office for the conduct of his official duties in camp.
The Engineers (Fabri)
The army always had some body of professional engineers with it for siege work, bridges and roads, fortifications and other construction projects. Since an army might engage in several construction projects simultaneously, all requiring close supervision by the fabri.
At some times in the long history of the legion it also carried a variety of artillery pieces with it. a ballista, a two armed stone thrower. Onager, a single armed stone thrower. a small arrow shooting scorpio. The catapultae were the arrow shooting pieces, the ballistae were the stone throwers. Catapults could be relatively small and carried on a single mule. Judson estimates the weights at 84 pounds for the small ones and up to 600 pounds for the large ones. Even the small ones would require two men to operate them. By Vegetius' time it seems that the legion was equipped with 50 to 60 small catapultae, probably scorpiones, and 10 ballistae. In the earlier legions the ballista was preferred to the onager since it was more efficient, under the late empire the onager became the predominate siege weapon. Imperial legions had an artillery piece, the carroballista, that appears to have been mounted on a special cart.
The army must have had significant quantity of extra supplies such as tentage leather, clothing, weapons, cordage.
Defensive stakes: The stakes found at some locations are interpreted as additional defensive works. They are, typically, about 5' long, tapering from a maximum width of 4" at the center to a point on either end, with a recessed "handle" in the middle. Each soldier may have carried one stake or they could have been carried by mules. If the stakes were tied together to create an additional defense on top of the walls of the camp then 6852 feet of wall would need to be covered. The stakes are about 4" in diameter, 3 stakes to the foot would require 14,506 stakes to defend the entire circuit of walls. Since there are about 19,440 legionary soldiers in the typical 4 legion army there would be enough stakes for the purpose if each soldier carried one. A stake of dried wood some 5' long, tapering to both ends and only 4" wide at the widest would not weigh more than several pounds. One mule could conceivably carry 100 of them, 145 mules for the entire supply or 36 mules per legion. The burden for one mule would be a bundle of 10 by 10 stakes, or 40 by 40 inches, perhaps not too heavy but possibly too unwieldy for a single mule load.
Wounded soldiers may have been carried from the battlefield on their shields, but those not able to walk would have had to have some alternate form of transportation, either to get from camp to camp or to be returned to some more secure base camp. In either case, it would seem likely that the legion would have some type of ambulance carts available for this purpose. For ambulances I have allowed 1 light two wheeled horse-drawn cart per cohort, driven by one of the assistants. The remaining 10 assistants care for the mule train. Trajan's column shows soldiers being cared for by what look like other soldiers. However, it seems that most doctors in the Roman world were slaves or freedmen. Therefore, if the legions took actual doctors with them then it seems likely that they would have been slaves or freedmen, not soldiers. The soldiers themselves may have assisted in caring for the wounded, analogous to field medics.
Hospital tents: It seems reasonable that the very ill or seriously wounded would be cared for at some kind of central aid centre, a field hospital of sorts. If there were hospital tents they could have been relatively small, on the same order as an officer's tent which could easily be carried on the ambulance carts. On the other hand, it is likely that the very ill or gravely wounded would not continue to accompany the army but would be left behind in some kind of secure base camp, reducing the need for a hospital.
At least by the late republic the commander employed professional body guards made up of paid mercenaries. It seems that the number of bodyguards was not standard but depended on the general. For this model I have used a strength of one cohort, 480 soldiers. The bodyguards are foot soldiers but travel mounted so that they can keep up with the general. Since they are foot soldiers, not cavalry, they are organized into a cohort. The cohort strength, 480 men, is equal to just under 15 turmae, about 1 1/2 alae of cavalry. The small units at the top represent the commanding officer of the bodyguards, his signiferi, aeneatores and pack train. Following the commander is one century of 80 men. Immediately behind the 3 aeneatores of the commander is the officer rank (detail below) followed by 13 ranks of soldiers. Since the bodyguards would travel in a battle-ready mode, their personal gear would have to be carried by pack mules. I have followed the standard I used above, 1 mule for each five soldiers. There are 9 mules with tents for the 8 contubernia of soldiers and their officer. Then there are 18 mules carrying the personal gear of the century, and finally 4 tents for the servants. The bodyguards escorted the commanding general as a unit. Their march and baggage train formations are shown below. The guards are in red, the baggage train is blue.
The evocati were retired soldiers who came back to serve at the specific request of the commander. They sometimes formed part of the bodyguard, otherwise served as special units at the service of the general. They are described as foot soldiers who each had a horse. I have not found any indication of the numbers of evocati; it seems probable that there was no "typical" number but that it would depend on circumstances and generals. I used a total strength of one cohort, and used the same formation and baggage model as for the bodyguards.
(contubernales, comites praetorii)
It was the custom for young men of noble families to accompany the Legions as a part of their education process. It is assumed that each youth had a personal servant and tent. The servants could have shared a single tent. For 8 youth there would be one additional tent for servants.
Under the republic the army would be commanded by either a consul or a praetor. A consul would be accompanied by 12 lictors, a praetor by 6. For a consular army of 2 legions and 2 allied units the 12 lictors would require 2 tents, three mules for their personal gear which they could not carry themselves, and one tent for the servants.
(Consul, Praetor, promagistrate or imperial general)
The commanding officer of the army certainly had more elaborate accommodations than the other officers. If the general's tent was the size Connolly indicates it would take 4 mules just to carry the poles and tent leather. In addition the general is allotted 20 personal pack animals and 1 extra riding horse led by servants, and 4 tents for servants. The pack train did not move with the general. The entourage that would have moved with the general on the march is shown below. The general, consul or praetor, is described as moving with a large entourage accompanying him. The commanding officer of the army may have been a dictator, consul, praetor, promagistrate or imperial general. For this illustration I have depicted a consul with his 12 lictors. A dictator would have had 24 lictors, a praetor only 6. Imperial generals would not have had lictors. In fact it seems that they were used in many capacities and may not have occupied this particularly place in the order of march.
The army, at least under the republic, had a quaestor assigned to it to keep the accounts. The quaestor is assigned a large tent the same size as the general's; a 4-mule load. He has 2 mounted personal servants. The quaestor would have required a number of clerks, but no specific numbers are given. The pack train consists of 4 mules for tents, 10 mules for the quaestor's personal gear, 6 mules for the tents of the clerks (one each as an office), 7 mules with official documents and equipment (two for the chief clerk, one each for the others), 4 mules for the servants tents, and an extra riding horse for the quaestor.
The number of auxiliary cavalry varied greatly from army to army. It seems that Caesar may have employed the greatest numbers, 4,000 to 5,000. Other armies may have employed almost none. For the purpose of the model a moderate force of 8 alae, 2,640 cavalry is used. There were also 4 Roman alae (one per legion) for a total cavalry force of 3,960 men. Distribution of the cavalry and other mounted units during the march: The mounted soldiers in this army are: 4 alae of Roman cavalry, 8 alae of auxiliary cavalry, 1 cohort of bodyguards and 1 cohort of evocati. The sources I have used indicate that various parts of the column were protected by cavalry but do not give unit identifications or numbers. For the purposes of guarding the column I am considering the mounted foot soldiers, the bodyguards and evocati, as cavalry. The mounted units are distributed: Roman cavalry: 4 alae: 1to the vanguard, 1 as guard for the officers, 2 to the army equipment and supply baggage; auxiliary cavalry: 8 alae: 1 to the scouts, 1 to the vanguard, 2 to the rearguard, 2 to each flank; evocati: to guard the officers baggage train; bodyguards: to guard the general. This arrangement puts three alae in front of the column (one with the scouts, two with the vanguard), two on each flank and two with the rearguard. It distributes the remaining 3 alae and the two mounted cohorts at intervals along the column of march.
Iron Supply, Forge and Smithing
The army in any extended campaign would have to provide for the repair and replacement of its weapons. The wood parts could be manufactured from materials found through forage or manufactured on site but iron would have to be either captured from enemy stockpiles, recovered from broken Roman weapons or recovered enemy weapons, or drawn from a supply taken with the Army. It does seem likely that the army would take some supply of bronze and iron with it and not rely solely on recovered or found supplies of these essential materials. Each soldier must have carried a minimum of 10 to 15 pounds of metal in armour and weapons. In addition there would be tools, parts of harnesses, artillery fittings, arrow points, sling shot (often made of lead). An army of roughly 20,000 soldiers would carry, then, something like 200,000 to 300,000 pounds of metal weapons and tools. If as little as 1% of the total weight of metal were taken as a reserve that would be 2,000 to 3,000 pounds. With an average mule-load of 200 pounds it would take a train of 10 to 15 mules. The repair of weapons would require a small forge and smithing tools. I have not been able to find any information on portable Roman forges. Given the difficulty of wheeled transport, the ideal forge would be carried by mules. It may be possible that a simple portable forge could consist of a dozen or so fire bricks and a bellows. The loose bricks and bellows could be carried on a single mule, the smithing tools on another. A small 200 pound anvil could consist of two or more parts that, when disassembled, could be loaded another mule. Thus a very small, primitive, but workable blacksmith setup could be transported on as few as 3 mules. If the forge consisted of these small parts -- bricks, small anvils, tools -- it would look much like any other mule load. Since each legion has a supply train of 288 mules, over a thousand for the whole army, it seems adequate to assume that some of these supply train mules were used to transport the necessary quantities of metal and materials for portable forges.
Spoils of War
The spoils of war figured large in the army's activities. Some campaigns netted enormous quantities of precious metals, objects of art and slaves. The quantity of spoils actually accompanying an army in the field would be highly variable: none at the beginning of a campaign, perhaps a great deal at certain times. Some of the booty would have been transported to secure forts in rear areas. At some times, certainly, the acquired spoils would have had to travel with the army itself. It is likely that an important part of the spoils of war would be the transport necessary to move it -- wagons, horses, mules.
Time to Fortify the New Camp
Most estimate that it took 3 hours to complete the fortifications around the camp, Judson estimated 3 to 4 hours. The first legionary soldiers to arrive with the vanguard do not begin fortification work but, rather, set up a protective screen to defend the site and the new arrivals. Work on fortifications do not begin until the first of the regular legionary forces arrive.
Rate of March
The Roman militari gradu, regular march cadence, was 100 paces per minute, the quick march cadence was 120 paces per minute. The Roman foot was (0.9708 English foot). The pace was 2.5 Roman feet, (29.124"). At that rate the army would move 14,562 feet per hour, 2.76 miles per hour. It would take each unit a little over 3 1/2 hours to complete the ten miles between camps. Because of the length of the column, it would take a little over 8 hours from the time the first units left camp until the last of the rearguard arrived at the new camp.
Peaceful and Hostile Marches
The Romans are said to have enforced the camp building procedure every night, whether in peaceful or hostile environments. The main difference seems to be that the fortifications were more elaborate when there was a potential threat. Otherwise, the description of the march as given here would be similar whether the army was moving through Italy on its way to the provinces or through Gaul and Spain during a campaign.
All ancient people rose early. In summer months the army would be up and moving by 6. This would allow them to complete the day's march at about 3 in the afternoon, leaving a good portion of the day for the other tasks that would still need to be done -- caring for the pack animals, repairing equipment, cooking meals, scouting the area, foraging for food, firewood, restocking water supplies, drill and relaxation.
The Order of March
Scouts - A scouting unit of cavalry and skirmishers was stationed 800 yards in front of the main body. 1/2 of the skirmishers and 1/8 of the auxiliary cavalry were assigned to scouting. That is, 4 centuries of archers, 4 of slingers and 1 ala of auxiliary cavalry. The pack animals for these units are positioned with the overall army supply train.
Vanguard - The vanguard consisted of one legion and cavalry. The legion was chosen by lot daily. The vanguard would have been some distance in front of the army, about 800 yards as a likely distance.
Survey - The survey group was comprised of one man from each contubernium.
Pioneer - The composition of the pioneer corps included one cohort and 10 engineers.
Officer Corps - Chief among the officers is the quaestor. Then there are the officers of the 4 legions: the legati in charge of each legion and the 6 tribunes assigned to each legion. Each legatus is accompanied by one of each of the types of aeneatores. Also included is the commander of the allied cavalry and the quaestor. The quaestor is accompanied by 4 clerks. The officers are grouped by legion.
Baggage Train - First come the evocati as a guard unit. Then the baggage of the commanding general and the officers. This is followed by the baggage of the legionaries, then that of the staff for the legions, the Roman alae and the archers and slingers. In roughly the middle of the train there is another mounted guard of 2 Roman alae. They are followed by the baggage for the army; its artillery, supplies and food. And finally there is the baggage of the evocati, bodyguards and auxiliary cavalry. In the model above the baggage train has been grouped by similar types. That is, all of the artillery, food and supplies for each of the four legions has been grouped together. The Romans also organized their order of march legion by legion, with the baggage of each legion accompanying the legionaries. Were a legion to march on its own, as they often did, this would approximate the formation, although the legion would probably have advance and rearguards that are not shown.
Rearguard - Connolly describes the rearguard as light and heavy infantry plus a considerable number of auxiliary cavalry. The alae are at the end since they are the more mobile and could more easily fight a rear guard action and then catch up to the main body.
Flank Guards - Some cavalry units would have been used as flankers to protect against surprise attacks.
The Entire Column - This column extends almost 15 miles. The column would be considerably extended if the roads being used did not allow the army to march 6 abreast. It is significant to note the extent of the baggage train, nearly 8 miles from front to back. This vulnerable part of the column would have been difficult to defend. If there were an attack on the middle of the baggage train it would be approximately 4 miles to the rearguard and to nearest legion front, but nearly 6 miles to the foremost legion. Signaling horns could raise the alarm from one end of the column to the other almost instantaneously. The mounted rearguard could cover the distance in about 10 or 15 minutes but would take between one and two hours for the legions to arrive on the scene.
Men and Animals - Contubernium, 10 men are assigned to one tent, eight sleeping, two on watch. They have one pack animal to carry the tent and other supplies and a servant to handle the animal. To simplify the model all pack animals are considered to be mules, animals ridden (by the cavalry and officers) are horses and oxen are not included.
Cavalry - The normal ala formation was 40' wide so that it could move in formation on the 40' road. On a 20' road the Cavalry would march by turma, 8 ranks of 4 files.
Servants - One servant is assigned to each mule. Since servants do not keep watch, there is one tent for each 8 servants.
Legatus - One to command each legion under the general.
Quaestor - One to the army.
Contubernales, comites praetorii - Young nobles accompanying the general as aides. He does not specify a number.
Apparitores - Lictors, scribes and servants. No numbers given.
Body-guard - Again, no numbers are given. They are described as sometimes drawn from the army, sometimes drawn from the Evocati, sometimes hired mercenaries.
Evocati - Retired legionaries serving as a special corps at the invitation of the general, their former commander in some cases. They were formed into regular centuries but served a variety of functions including orderlies, scouts and protection of the general.
Fabri - Engineers, led by the Praefectus Fabrum. Some may have been leginaries, others would have been specialists. No numbers are given.
Antisignani - Although disputed by some of his authorities, Judson says that each maniple may have had one contubernium, 10 men, who were antisignani. They would operate in front of the legion as light troops or skirmishers. They marched without heavy baggage. Caesar, he says, "regarded the body as a school for centurions."
Mules - Load. The maximum load for a mule is given as 200 lbs. Number. There are between 520 and 640 per legion, depending on the actual strength of the legion. Spacing. In the march he allows 10' for each rank and 5' for each file.
Equipment and Supplies
Artillery - There are two types, the catapultae (bolt throwers) and ballistae (rock throwers). The catapulta weighs between 84 pounds (smallest) and 600 pounds (largest). The ballista weighs about 200 pounds. Each legion had 55 carroballistae (smaller ballistae) and 10 onagri. Since no mention is made of wheeled transport, all artillery items are considered to be carried on mules. Ballistae. The smallest ballista had arms 2' long, powered by skeins 4" in diameter. The largest had arms 4' long and was powered by skeins 6' to 8" in diameter. The ballista could throw a 6 to 8 lb. stone 450 to 500 yards. The onager was known all along but only came into general use quite late when the more complicated but more efficient ballistae went out of use. He estimates the weight of an onager as 2 to 6 tons. It probably had a range 400 to 500 yards. Onagri were not used in the field but were only for sieges Number. By the time of Vegetius 10 onagri were assigned to a legion, or 1 per cohort, one carroballista per century. Probably the artillery was not actually distributed to those units, it is more likely that the artillery was centrally concentrated and that the description reflects a formula to determine the number each legion would have. Staff. Although there is no direct evidence he believes there would have been an artillery commander, a principalis, in overall charge. Similarly, each carroballista would need a junior commander, an aimer, 1 or 2 men to turn the winch, and 1 or 2 animal handlers who could also help re-supply ammunition. He assigns a total 10 to the carroballista. Vegetius suggested that a team of 11 men were required for each. The onager, especially the larger ones, would have required more men. The total artillerymen per legion would be about 650, plus artificers. They were sometimes called ballistarii. They may not have been in special units, but may have been drawn from the regular legionary force. However, after 300 AD they were assembled into their own units.
Tents - The standard soldier's tent is 10 feet square and weighs 40 pounds. The centurion's tent was 10' by 20' wide and was probably carried on a small two wheeled cart pulled by two mules and driven by a servant. The cart would also have carried extra gear and supplies for the century and been a place to store personal gear in the case of battle. Tribune and officer. The tribune's tent was taller, on a box-like structure of poles. General. The general's tent may have been some 200 square feet. Caesar, even carried a mosaic floor in sections.
Carts - Use. Although not used extensively, he believes the Roman army would have used small mobile two wheeled carts pulled by two animals (mules, horses or oxen) for at least some of the baggage. Number. Each legion would have had 60 carts for its artillery, 60 for the centurions, and another 30 for "sundry" needs such as ambulances, engineering supplies. Pace. Caesar's light duty two wheeled carts as capable of 4 mph.
Food - The daily grain requirements were 3 lbs. per day for each man. Each man carried 10 day's rations (30 pounds) with another 2 days rations being carried on the mules. 125 mules were assigned per legio for ration reserve function but 1,250 for the army as a whole. "Ration reserve" may mean that they carry rations for two days and then act as a reserve for forage or loot or other needs. The mule-borne rations would be consumed first to free those mules to carry found foraging and or booty.
Booty - The army may acquire considerable booty as it conquered land and cities. He does not attempt to cite any specific number of animals or servants or hostages associated with booty.
The legions marched at 3 miles per hour. Carts were capable of 4 miles per hour.
Order of march:
Scouts. An advance force was sent in front of the army to scout for enemy ambushes. This force was composed of about 1,000 cavalry plus some light infantry of archers and slingers. They operated about 800 to 900 yards (roughly 1/2 mile) in front of the vanguard.
Flank. 1,000 cavalry on each flank as protection from ambush.
Rear Guard. 1,000 of the auxiliary cavalry with the rear guard.
Order of march::
Transport - The preferred method of land transport was by mule pack. The use of wagons was limited because without the horse collar neither horses, mules nor donkeys could pull heavy loads and oxen were slow. Human labor moved lighter weights. The maximum human load that could be carried more than a short distance, 40 or 50 yards, was 50 to 60 pounds. Anything larger required pack animals. The very heavy loads were drawn by oxen in wagons.
Mules - They were normally from a female horse and male donkey, were preferred over horses for several reasons: they were less temperamental, easier to train, their skin is tougher and less easily damaged, can tolerate extremes of heat and cold better, requires less water, needs less sleep (4 to 5 hours per night), its hooves are harder and is more sure-footed. The mule walks at just over 3 miles per hour but can cover up to 50 miles a day over level ground and lightly loaded. Because of these advantages, pack mules were widely used throughout the world until this century. Evidence seems to indicate that ancient mules were roughly the size of modern mules: between 52 and 60 inches at the withers (13 to 15 hands), the largest as high as 64 inches, weighing between 6000 and 900 pounds, able to carry 30% of their weight (25% on hilly ground). The load could be between 200 pounds for a smaller mule and as high as 270 pounds for a large one. An important restriction was that the weight had to be evenly divided on either side of the pannier. If a single large weight, a stone, for example, were carried then the mule could only bear about half the weight.
Donkeys - They were also used, though it seems that mules were preferred. They are smaller than mules, between 36 and 60 inches at the withers, carrying proportionately smaller loads. A small donkey could carry about 120 pounds, a large one the same as a mule.
Horses - Ancient horses were probably about the same size as the mules. Large draft horses were not known in ancient times. Four well-bred horses might have been able to pull 2 to 3 tons at about 4 to 5 miles per hour. But the ancients actually used them to pull light loads, such as a chariot and its driver, maybe 440 pounds at a relatively fast pace. Horse drawn fast vehicles could average about 7 mph over the course of a day.
Oxen - Oxen can pull 1.5 times their body weight but can travel only 1 miles per hour, less if there are obstacles in their way. However they do have advantages in feeding since they can consume 1.5 times 3% instead of 2% of their body weight. They can survive on lower quality food since they can eat more of it. One ancient formula says that they should be fed 15 lbs. of hay and 15 to 20 pounds of mash per day.
Carts and Wagons - Two wheeled Carts and four wheeled wagons were both used. Oxen were used for the wagons and the heavy carts. Horses were used for light fast 2-wheeled carts, usually personal transport. A difficulty with the two heeled heavy carts was that the load had to be precisely balanced over the wheels or it would exert pressure on the pole either down on the yoke or up on the girth strap. There may have been a standard gauge for wagons of 112 to 114 cm. This is found in grooves worn by wagon wheels in various places. Heavy wagons were usually drawn by oxen, horses were used only for light fast transport. Both carts and wagons were designed to be drawn by two animals. The method of attaching them to the vehicles was yoke and pole, suitable for oxen but not for horses since the yoke choked the horse if too heavy a load were pulled. The horse collar was not invented until centuries later.
One can only try to imagine the confusion inherent in an
It would have been difficult for anyone to see much of what was happening. A small army, the equivalent of just 4 legions plus cavalry, would have a front of nearly a mile. A larger army, typical of the late Republic and early Empire, might be made up 8 to 12 Legions and have a front of several miles. Moreover, battlefields were selected because they were flat and allowed the armies room to manoeuvre. But, being flat, they offered no vantage points higher than the back of a horse. Because most warfare took place in the summer months, dust would have been a frequent problem. Distance and dust would have made it nearly impossible to tell what was happening at other parts of the battle. The noise would have been horrific. Initially there would be the sounds of trumpets and thousands of men yelling on both sides. During the battle there would be added the sounds of shields and swords smashing together, orders shouted, men calling encouragement to their comrades or shouting threats to the enemy, the thunder of horses hooves, the cries of wounded and dying men. It is possible that the regular infantryman could hardly hear his own officers.
The nice neat unit formations we see on paper simply disappear, replaced by a melee of men. The battle line is not straight, or well defined, or stationery. Rather there is a moving seething mass of men sometimes hotly engaged, sometimes falling back. At a quick glance it would be difficult to tell which side was having the better of it. At times it was, apparently, even difficult to tell which side was which. Any model of Roman fighting has to depart from the tidy paper diagram and reflect the inherent confusion of the real place. Elaborate manoeuvres and complicated tactics would probably not have even been possible. It would have been important for the individual soldier to stay in close contact with his comrades on all sides of him, to feel and sense their presence and support even when he was tightly focused on the enemy in front of him. Any sort of coordination between units must have been difficult and, at times, impossible. Large scale coordination would have been extraordinarily difficult, but not impossible as we will note later.
The ability of the commander to control his army during battle
was probably not great.
As noted above, it would have been difficult to see or hear much of what was
happening during the battle.
1,700 yards - masses of troops can be recognized
1,300 yards - infantry can be distinguished from cavalry.
1,000 yards - individuals can be seen.
700 yards - heads, crossbelts etc. can be distinguished
500 yards - uniforms recognized, reflections from weapons
250 yards - officers recognizable, uniforms clear
Visibility would be obstructed by men and horses in the line of sight. The ability to distinguish friend from foe would be more difficult when seeing units from the sides or back. Everything would be in motion. And even a little dust in the air would significantly reduce the amount of detail and color that could be seen at a distance..
Roman commanders seem to have favoured a position on their right flank, traditionally the strongest and most aggressive wing of the army. Even Pompey at Pharsalus, where the major action was expected on the open left flank, took up his position on the right. From this side a general could hardly have seen what was going on some 1,700 yards away on the left flank. For information he would have had to depend on messengers or other indicators. Pompey is said to have deduced the outcome of the cavalry fighting by observing the dust clouds raised. If the riders could travel at the "rapid" pace of 8 mph it would take about 13 minutes to ride the length of a 3,000 yard battlefield. By the time the general could receive the report, issue new orders, and send the rider back there would be a delay of nearly 1/2 hour. Some battles may have lasted half-a-day, but others were over in a matter of a few hours. In those cases a delay in communications of 1/2 hour would be significant. For this reason the Romans used horns to signal orders over long distances. The general would still be dependent on dispatch riders to give him information about the status of events at distant points but he would have been able to issue simple types of commands via horn signals. Keeping noise factors in mind, there would have had to have been a relay system to ensure communications with the furthest units.
Intricate manoeuvres would be hampered by an assortment of obstructions on the battlefield. Most depictions ignore this. True, most battles were fought on relatively flat smooth ground. Even a flat field would have many minor obstructions. A relatively small boulder or bush could seriously disrupt the tidy ranks and files that appear on paper. In addition to natural obstacles there would be a considerable amount of debris from fighting. Along a front of 100 men there would be a between 200 and 400 pila that had been thrown - many now stuck in the ground, some (say a dozen) lodged in a discarded shield or in the corpse of a casualty. Along that same 100 man front a casualty rate of just 3% would leave 6 bodies (3 from each side) lying on the field. Near each of the 6 bodies would be a sword or spear, a shield and possibly a helmet lying on the ground as well. There could be another 12 wounded who may have been removed from the field but whose equipment might be lying around. A front of 100 would take up roughly 300 feet. Along that front there would be one pilum every 9 inches, a pilum-scutum tangle every 25', a body every 50' and equipment of the dead and wounded every three feet. This detritus of battle could be scattered for some distance on either side of the current line of fighting, but even so, it would remain as an obstacle to troop movement. Just about every century on the line would find itself moving over and around these obstacles. At a minimum this would disrupt the ranks and files. It could be much more serious when soldiers tripped and fell, as they would almost inevitably have done. Manoeuvring by any unit would have to be over and around these obstacles. It is not impossible to maneuver, but it is not as simple, orderly and precise as it appears on paper.
In the second half of the 2nd century BC the Romans made the momentous decision to abolish the legionary cavalry and employ foreign horsemen, raised in the areas of operation and led by their own chief or Roman commanders. Under the republic command had been exercised by native princes, but under the empire commanders were soon drawn exclusively from Roman equestrian prefects.: During the late republic most cavalry were Celtic and used a spatha, 60 to 70 cm in length, and a flat oval shield. The auxiliary infantry varied from light-armed troops such as the slingers shown on Trajan's column, who wore no armour at all and, if the artist is to be believed, no shoes either, to fully armed troops whose armour was identical to that of the legionaries but of inferior quality: the only difference was the use of the flat shield rather than the scutum. Unarmoured cavalry was comprised of one hand spear-bearers, pike-bearers and lancers, other skirmishers (mounted-bowmen or javelin-throwers). The spear-bearers are those who approach the enemy ranks and fight them off with spears or charge and drive them back with pikes like the Alans and Sarmatians, the skirmishers are those who discharge weapons from a distance, like the Armenians and those of the Parthians who do not carry pikes. ...The name of skirmishers is given to those who do not come to close quarters but discharge their weapons from a distance; and of these some use throwing-spears and others bows. ... But others first discharge their weapons and then join battle with the enemy, either retaining one of their spears or using a sword (spatha).
It is hard to wheel about with square formations -- are well arranged in as much as those so drawn up are in ranks and files and it is organized for easy charging and withdrawing; and only with this formation do the officers fall in a single body upon the enemy. The best are those that have the double measurement in the length rather than the breadth; for example, if there are ten men drawn up along the front and five deep. For such formations are oblong as regards number, but square in actual shape. For the length of the horse from head to tail fills out the square since the length of the horse is three times a man's width at the shoulders and as when they draw up nine in line along the front, they make the formation three deep. For this too should be borne in mind, that the cavalry drawn up in depth do not afford the same assistance as to infantry in depth, for they do not push on those in front of them, since one horse cannot push against another in the way that infantry push on with their shoulders and flanks, nor when they are contiguous with those drawn up in front do they constitute a single massed weight for the whole body of troops; on the contrary, if they mass and press against each other, they rather cause the horses to panic. An oblong formation in which ... the front is greater than the depth ... is better in contests. ... A single line along the front with no depth is convenient for unsuspected raids ... but for contests it is very disadvantageous. Horsemen gallop in circular patterns throwing their javelins at targets. In the practice formations the turma appears to string itself out as individuals following one behind the other through the loops of the pattern.
The spatha blade was 34 inches. Josephus mentions three or more light javelins being carried in a quiver. At one gallop stride a 16 hand horse can cover at least 16 feet. A ploy for confusing the enemy as to the size of the army was for the cavalry were to be lined up extremely close together so that the whole unit looked much smaller than it really was. This left no room to manoeuvre. Each horse was allotted a space 3 ft wide by 8 ft long. I have measured this out with a horse. Katchina at 14.3 hands hits easily into this space lengthwise, and when he is in fit condition into the width also. Nizzolan, of oriental blood being pure Arabian, and a much leaner type but slightly taller than Katchina at 15 hands fits, with a little room to spare. There is just sufficient room widthwise for the troopers knees.
The speed of a foot javelineer prior to the throw was very important. The speed of the horse definitely lent power to the cast. As it leaves the hand the speed of a modern man's javelin weighing 800 grams is between 27 and 30 meters a second. A speed of 33 meters per second is exceptional. Loss of force occurs in flight. As it reaches its highest point, before starting on its downward flight, it is traveling at approximately 9.81 meters per second.
Light-armoured cavalry ... were considered to be the most versatile and the most useful of all the styles of mounted troops. They were usually positioned on the flanks of an army, from where they could try to harass , and hopefully, encircle the enemy's wings. ...This type of cavalry was particularly well suited to skirmishing, making constant sallies against the enemy in order to exhaust the infantry and force them to be continually on their guard. Unlike the heavy-armoured cavalry, whose role it was to charge an army directly, the light-armoured mounted troops were specifically equipped to wear down an enemy through persistence.
Cavalry is only an effective arm when it is offensively employed, since once it is forced to become defensive, and is confined in a restricted area, it loses its main advantages of mobility and speed. ... The charge must be decided promptly, and executed vigorously; always met and carried out at speed ... No distance can be laid down at which to charge, it depends on so many different circumstances. When the ground is favourable and your horses in good condition, you can strike into a gallop sooner; but the burst, the charge itself, must always be reserved till within 50 yards, for in that distance no horse, however bad, can be left behind, nor is there time to scatter, and they fall upon the enemy with the greatest effect.
Well disciplined, determined infantry, could rarely be defeated by this manoeuvre (charging) ... One of the main reasons for this is that horses, whenever possible, will avoid a direct collision with an obstacle, and thus when they are confronted by a wall of unyielding spear points they will instinctively try to wheel away from them. Only if the infantry has lost its nerve, and the courage needed to hold fast has gone, will the charge be able to break the line and scatter the men in disarray. If, however, he does persist, and charge home on our heavy infantry centre, then the second and third ranks of the legions will close up on the front, until they are actually touching, so as physically to support them under the shock of impact; thus the attacking horsemen will be confronted with an unbroken and immovable hedge of spear points at the level of a horse's chest. Spearmen in the fourth rank will thrust at them, and those of the fifth and flowing will throw their spears overhand. By this means we cannot fail to repulse the enemy and force him to retire in disorder with heavy loses.
When the cavalry engaged in close-quarter fighting with infantry, their height advantage would become a very effective means of slashing at the heads and backs of their opponents, although, of course, they themselves would be vulnerable to leg wounds. If, however, they were engaged with enemy cavalry, the wounds incurred would be of a different nature, and the battle itself must have been absolute mayhem, with horses rearing and throwing their riders on to the ground, where they would stand little chance of escaping the hooves of the other mounts. The report of a cavalry officer who fought at the Battle of Balaclava, although comparative, paints a graphic picture of the sheer horror and confusion that was presumably present at all such fights: 'I can't say I saw the man who hit me, we were all in a crowd cutting and hacking at each other, and I did not know till some time after that I was touched when my wrist got stiff, then I found the cut through my coat, it was only bruised for a few days ... The wounds our long swords made were terrible, heads nearly cut off apparently at a stroke, and a great number must have died who got away. Our corporal who was killed was nearly cut to pieces, his left arm nearly severed in four places ... All of the Russians seem to cut at the let wrist, so many men lost fingers and got their hands cut.'
Among the aspects of Roman warfare the use of elephants has to be one of the hardest to understand. There is ample evidence that they were used both against the Romans and also by them. There is some evidence that they were effective in some instances, but there are more examples in which trained soldiers fought against elephants quite effectively. The best testimony for their [elephants] usefulness in combat still remains, however, the fact that even the great commanders always used them again and again, especially Hannibal and also Caesar. . . . If we consider the entire experience of the military history of antiquity, we may say that the usefulness and the actual use of elephants for battle may under any circumstances not be rated too highly. Against peoples who were still not at all familiar with them and against cavalry and sharpshooters they had some successes, which were, however, as in the case of the battles against Pyrrhus, for example, very greatly exaggerated by the losers in order to find an excuse for their defeat. Troops who are familiar with them and do not fear them, who know how to avoid them and how to attack them properly, are able to deal with them . . . by skillful use of their weapons. . . . The elephant is not at all invulnerable but even has a rather sensitive hide, and even if spears and arrows do not kill him outright, they still penetrate so deeply that they remain imbedded in his body, and the pain makes the animals uncontrollable and causes them to shy away. It is reported often enough that they then penetrate into the ranks of their own troops, throw them into confusion, and bring about defeats. . . As the ultimate means of dealing with such cases, the mahouts ... each had a sharp steel wedge which they drove with a hammer into the animal's neck in order to kill him and render him harmless.
|Wages (per month)|
|Praetorian (guard in Rome)||240|
The Roman Era |
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In the design of modern computers, memory geometry describes the internal structure of random-access memory. Memory geometry is of concern to consumers upgrading their computers, since older memory controllers may not be compatible with later products. Memory geometry terminology can be confusing because of the number of overlapping terms.
The geometry of a memory system can be thought of as a multi-dimensional array. Each dimension has its own characteristics and physical realization. For example, the number of data pins on a memory module is one dimension.
Memory geometry describes the logical configuration of a RAM module, but consumers will always find it easiest to grasp the physical configuration. Much of the confusion surrounding memory geometry occurs when the physical configuration obfuscates the logical configuration. The first defining feature of RAM is form factor. RAM modules can be in compact SO-DIMM form for space constrained applications like laptops, printers, embedded computers, and small form factor computers, and in DIMM format, which is used in most desktops.
The other physical characteristics, determined by physical examination, are the number of memory chips, and whether both sides of the memory "stick" are populated. Modules with the number of RAM chips equal to some power of two do not support memory error detection or correction. If there are extra RAM chips (between powers of two), these are used for ECC.
RAM modules are 'keyed' by indentations on the sides, and along the bottom of the module. This designates the technology, and classification of the modules, for instance whether it is DDR2, or DDR3, and whether it is suitable for desktops, or for servers. Keying was designed to make it difficult to install incorrect modules in a system (but there are more requirements than are embodied in keys). It is important to make sure that the keying of the module matches the key of the slot it is intended to occupy.
Additional, non-memory chips on the module may be an indication that it was designed[by whom?] for high capacity memory systems for servers, and that the module may be incompatible with mass-market systems.
As the next section of this article will cover the logical architecture, which covers the logical structure spanning every populated slot in a system, the physical features of the slots themselves become important. By consulting the documentation of your motherboard, or reading the labels on the board itself, you can determine the underlying logical structure of the slots. When there is more than one slot, they are numbered, and when there is more than one channel, the different slots are separated in that way as well – usually color-coded.
In the 90s, specialized computers[which?] were released where two computers that each had their own memory controller could be networked at such a low level that the software run could use the memory, or CPU of either computer as if they were one unit.[clarification needed] With AMD's release of the Opteron, and Intel's corresponding systems that share more than one memory controller in a single system have become common in applications that require the power of more than one common desktop. For these systems schemes like Non-Uniform Memory Architecture are used.
Channels are the highest level structure at the local memory controller level. Modern computers can have two, three or even more channels. It is usually important that, for each module in any one channel, there is a logically identical module in the same location on each of the other populated channels.
Module capacity is the aggregate space in a module measured in byte, or – more generally – in words. Module capacity is equal to the product of the number of ranks and the rank density, and where the rank density is the product of rank depth, and rank width. The standard format for expressing this specification is (rank depth) Mbit × (rank width) × (number of ranks).
Ranks are sub-units of a memory module which share the same address and data buses and are selected via chip select (CS) in low level addressing. For example, a memory module with 8 chips on each side, with each chip having 8 bit wide data bus, would have one rank for each side for a total of 2 ranks, if we define a rank to be 64 bits wide. A module composed of Micron Technology MT47H128M16 chips with the organization 128 Mib × 16, meaning 128 Mi memory depth and 16 bit wide data bus per chip; if the module has 8 of these chips on each side of the board, there would be a total of 16 chips × 16 bit wide data = 256 total bits wide of data. For a 64-bit wide memory data interface, this equates to having 4 ranks, where each rank can be selected via a 2-bit Chip Select signal. Memory controllers such as the Intel 945 Chipset list the configurations they support: "256-Mib, 512-Mib, and 1-Gib DDR2 technologies for ×8 and ×16 devices." "…four ranks for all DDR2 devices up to 512-Mibit density. […] eight ranks for 1-Gibit DDR2 devices." As an example, take an i945 memory controller with four Kingston KHX6400D2/1G memory modules, where each module has a capacity of 1 GiB. Kingston describes each module as composed of 16 "64M×8-bit" chips with each chip having an 8-bit wide data bus. 16 × 8 equals 128 – therefore, each module has two ranks of 64 bits each. So, from the MCH point of view there are four 1 GB modules. At a higher logical level, the MCH also sees two channels, each with four ranks.
In contrast, banks, while similar from a logical perspective to ranks, are implemented quite differently in physical hardware. Banks are sub-units inside a single memory chip, while ranks are sub-units composed of a subset of the chips on a module. Similar to Chip Select, banks are selected via Bank Select bits which are part of the memory interface.
Hierarchy of organization
The lowest form of organization covered by memory geometry, sometimes called "memory device". These are the component ICs that make up each module, or module of RAM. The most important measurement of a chip is its density, measured in bits. Because memory bus width is usually larger than the number of chips, most chips are designed to have width, meaning that they are divided into equal parts internally, and when one address "depth" is called up, instead of returning just one value, more than one value is returned. In addition to the depth, a second addressing dimension has been added at the chip level, banks. Banks allow one bank to be available, while another bank is unavailable because it is refreshing.
Some measurements of modules are size, width, speed, and latency. A memory module consists of a multiple of the memory chips to equal the desired module width. So a 32-bit SIMM module could be composed of four 8-bit wide (×8) chips. As noted in the memory channel part, one physical module can be made up of one or more logical ranks. If that 32-bit SIMM were composed of eight 8-bit chips the SIMM would have two ranks.
A memory channel is made up of ranks. Physically a memory channel with just one memory module might present itself as having one or more logical ranks.
This is the highest level. In a typical computer there will only be a single memory controller with only one or two channels. The logical features section described NUMA configurations, which can take the form of a network of memory controllers. For example, each socket of a two socket AMD K8 can have a two channel memory controller, giving the system a total of four memory channels.
Memory Geometry Notation
Various methods of specifying memory geometry can be encountered, giving different types of information.
(Memory Depth) x (Memory Width)
The Memory Width specifies the data width of the memory module interface in bits. For example, 64 would indicate a 64-bit data width, as is found on non-ECC DIMMs common in SDR and DDR1-4 families of RAM. A memory of width of 72 would indicate an ECC module, with 8 extra bits in the data width for the error correcting code syndrome. (The ECC syndrome allows for single bit errors to be corrected). The Memory Depth is the total memory capacity in bits divided by the non-parity memory width. Sometimes the memory depth is indicated in units of Meg (220), as in 32×64 or 64×64, indicating 32 Mi depth and 64 Mi depth, respectively.
This is the total memory capacity of the chip. Example: 128 Mib.
(Memory Depth) × (Memory Width)
Memory Depth is the Memory Density divided by Memory Width. Example: for a memory chip with 128 Mib capacity and 8 bit wide data bus, it can be specified as: 16 Meg × 8. Sometimes the "Mi" is dropped, as in 16×8.
(Memory Depth per bank) × (Memory Width) × (Number of Banks)
Example: a chip with the same capacity and memory width as above but constructed with 4 banks would be specified as 4 Mi x 8 x 4.
- List of device bandwidths
- Dynamic random access memory
- Random-access memory
- Memory organisation
- Memory address
- Memory bank
- Bank switching
- Double-sided RAM
- Dual-channel architecture
- Page address register
- Ultimate Memory Guide (PDF), Kingston, 2007, archived from the original (PDF) on 2011-07-13. |
Exposure to nicotine changes the way your brain functions.
Let's imagine your brain as a computer. Like a computer, your brain processes, stores and uses information. In a computer, information travels in the form of electricity moving through wires; information transfer is a binary process, with switches being either on or off. In your brain, neurons are the cells that transfer and integrate information. Each neuron receives input from thousands of other neurons throughout the brain, processes that information and makes any necessary adjustments before communicating the message throughout the body. While signals are conducted through individual neurons as electric current, it's a group of chemical messengers called neurotransmitters that actually relay those messages between neurons and other cells [source: National Institute on Drug Abuse].
Each neurotransmitter has its own specific family of receptors. Nicotine happens to imitate the neurotransmitter acetylcholine, and binds to those receptors (specifically those known as the nicotinic receptors). However, unlike acetylcholine, nicotine is not regulated by your body. While neurons typically release small amounts of acetylcholine in a regulated manner, nicotine activates cholinergic neurons (which would normally use acetylcholine to communicate with other neurons) in many different regions throughout your brain simultaneously.
Because of all of that unregulated stimulation and disruption, your body increases its release of acetylcholine, leading to heightened activity in cholinergic pathways throughout your brain. Activity in the cholinergic pathways calls your body and brain into action, and you feel re-energized. Stimulating those cholinergic neurons also increases how much dopamine gets released by the limbic system, which activates reward pathways in your brain. When drugs like cocaine or nicotine activate the reward pathways, it reinforces your desire to use them again because it feels good [source: National Institute on Drug Abuse].
Nicotine also stimulates the release of another neurotransmitter, glutamate; glutamate is involved in learning and memory and enhances the connections between sets of neurons. These stronger connections may be the physical basis of what we know as memory, and when you use nicotine, glutamate may create a memory loop of the good feelings you get and further drive the desire to use nicotine.
Nicotine also increases the level of other neurotransmitters and chemicals that modulate how your brain works. For example, your brain makes more endorphins in response to nicotine. Endorphins are small proteins that are often called the body's natural painkiller. It turns out that the chemical structure of endorphins is very similar to that of heavy-duty synthetic painkillers like morphine. Endorphins can lead to feelings of euphoria, and may explain nicotine's psychoactive and rewarding effects. |
Good news teenagers: a little extra sleep might have more benefits than previously thought. New research with fruit flies shows that a few extra hours of shut eye might hold the key to restoring the memory lost to neurodegenerative diseases.
Fruit flies have traditionally been used for scientific studies because they have a well mapped genome (DNA) with a lot of similarities to human genes. This genetic similarity and the fact that fruit flies are easy to mutate and relatively inexpensive allow scientists to use fruit flies to draw conclusions about potential change in humans as well. Researchers at Washington University School of Medicine studied the effects of increased sleep on short and long term memory in mutant fruit flies that have trouble making memories. Results showed that increased sleep, equal to about three to four hours over two nights for humans, restored memory in the mutant fruit flies.
Researchers tested three types of mutant fruit flies that had gene defects in either the rut gene, dnc gene (impair formation of memory), or the presenilin gene, which has been linked to early onset Alzheimer’s disease in humans. The researchers induced sleep using three different methods: by using a drug, increasing dFabp expression (a protein involved in sleep), or activating the neurons in the fan-shaped body region of the fruit fly brain. Researchers tested changes in memory by comparing the flies that got extra sleep to their sibling flies who did not receive one of the three treatments above.
Image Source: Caiaimage | Astronought Images
To test long-term memory, the researchers used something called courtship conditioning, and to test for short-term memory, the researchers used aversive phototaxic suppression (APS). APS tests a flies’ ability to learn to avoid light that is paired with some negative stimulus, like humidity or quinine (bitter taste).
Results showed that extra sleep restored brain functions in fruit flies with mutated memory genes, and that the method used to induce sleep did not change this fact. More simply, sleep allowed the flies to regain brain function that was removed by mutation. In the Alzheimer’s disease model fly, sleep was shown to reverse defects in long-term memory.
In conclusion, the researchers suggest that their findings show that the brain, when asleep, has a large capacity for behavioral change that is not possible when awake. While more research needs to be done to understand the mechanisms behind these findings, this adds to a growing body of research that suggest that sleep may hold the key to treating memory loss.
Feature Image Source: Now why am I here ? by Neil Moralee |
Examples of Skill-Building in Positive Supports
Creating a Positive Climate
The more positive interactions we have with another person, the more likely we will approach them in the future. Spending time reinforcing other people in all of our everyday interactions sets the stage for positive interactions in the future.
The Magic Ratio
Research on happy marriages report successful couples deliver five positive interactions for every one negative interaction. This approach can be used in other social situations as well. In fact, encouraging a 5 to 1 positive interaction pattern has been included in positive behavior support for many years. The visual on this page shows how an elementary school created visual prompts for teachers by putting posters on the wall reminding everyone about the Magic Ratio.
Positive reinforcement refers to rewarding a behavior to increase the likelihood it will happen in the future. What a person considers reinforcing is different for everyone and it is important to be aware of each person's preferences related to reinforcement. For example, we think we are reinforcing a child or adult because that is our intention. However, a person, event, or activity is only reinforcing if behavior increases upon its presentation.
There are important cultural differences in what each person considers reinforcing. A person's cultural values provide important clues about the types of positive reinforcement that will be most effective. An important part of developing rapport with another person involves understanding what is important to them and their unique preferences.
Behavior Specific Praise refers to the act of reinforcing someone immediately after the person engages in a valued behavior in a way that:
- Helps build positive relationships with others
- Includes a clear description of what the person has done that is appreciated
- Occurs as close in time to the behavior as possible
Example: “Antonio I really appreciate the way you helped me put the dishes away after dinner, you are very kind.”
It is important to use behavior specific praise in ways that demonstrate you understand a child or adult's culture, values, and preferences.
Example: "Antonio, you have made life easier for your mother by putting the dishes away and you are so important to our family."
- Listening to another person and showing interest
- Expressing appreciation
- Showing people they matter
- Finding opportunities for agreement
- Being intentional about your appreciation for someone
- Showing empathy and apologizing when a mistake is made
- Accepting others opinions
- Using humor
- Offering to help another person complete a task together
People who are approachable are good at sending signals that they can be trusted, are helpful to others, and interact in ways that meet the needs of others.
- Delivering high levels of reinforcing statements and actions
- Active listening and expressing empathy
- Mirroring eye contact patterns that are preferred by others
- Creating welcoming gestures
- Focusing on the comfort of others during interactions |
No, this isn’t a Jackson Pollock painting. It’s an image of all recorded hurricane tracks since the mid-1800s. Compiled using data from the National Hurricane Center and the Joint Typhoon Warning Center, the map by Robert Rohde tells us several things about hurricanes.
Global Warming Art
For a larger image, click here.
1. Hurricanes don’t form at the equator. It’s not because of sea surface temperatures, but rather the absence of the Coriolis effect, which drives the rotation of hurricanes.
2. The Pacific coasts of North and South America are largely spared by hurricanes. A big reason is that circulation patterns in the Pacific bring cooler waters to these regions.
3. If you were going to create a new island I would not recommend placing it several hundred miles south of Japan.
Like nearly all hurricane information, this dataset has limitations. Among them, according to Rohde, include:
Though the North Atlantic has a reasonably complete record of ship based encounters since about 1860, for most regions reliable information on storm tracks and intensity are not available before the satellite era of the 1960s. Further, only in the North Atlantic do planes routinely fly into hurricanes to measure their intensity. In all other regions, the intensity of the storms while far from land must be inferred from less accurate satellite observations. As a result, our understanding of tropical storms in the North Atlantic is much more complete than those over any other ocean basin, and the resulting portion of the image is more detailed.
In other words, storm counts in other regions are underplayed in comparison to the North Atlantic. |
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