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Your child isn’t perfect!
I know it sounds crazy, right?
The fact is all kids make mistakes and bad choices sometimes.
But we want them to because that’s part of growing up and how they learn right from wrong. The critical part of learning from these events is the adult response. If a child is punished without the proper support they may feel humiliation, shame or even anger which doesn’t support effective learning for the situation.
If, on the other hand, the adult provides the child time to reflect in a non-threatening environment then the child has time and the awareness to empathize, respect the consequences, and consider alternative choices in the future.
Adults can use these learning opportunities to teach empathy, compassion, and respect; that its okay to make mistakes as long as we take something positive away from each experience; and how to apologize to others so that children learn the accountability that goes along with a high social and emotional intelligence.
How does the Behavior Reflection and Apology Letter help?
The ThinkingIQ Behavior Reflection worksheet helps children recognize how their actions impact others and the Apology Letter template helps them to communicate their regrets so they may move forward in a positive way.
Reflect on your choices! |
Inventor: George Washington Carver|
George Washington Carver, born a slave in 1864 (approximately), contributed significantly to agricultural research. Although he was orphaned as an infant, endured hardship in pursuit of his education, and encountered racial prejudice at every juncture, Carver has become revered for his focus on the poorest southern farmers and his creative chemistry which served to revitalize the economy of the war torn South. He encouraged Alabama farmers to practice plant rotation and soil building techniques using nitrogen producing legumes like sweet potatoes and peanuts. To encourage this practice he developed over 400 products from the sweet potato and peanut. These and other products from pecans, cotton, and waste products virtually changed the economy of the South. Throughout his life he revered nature and felt his discoveries were from divine revelation and so belonged to everyone.
In 1894, Carver received a Bachelor of Agriculture from Iowa State Agricultural College and became a member of the faculty of Iowa State College. In 1896, he received a Master of Agriculture from Iowa State College. In 1896, Carver was recruited by Booker T. Washington to become the Director of Agriculture of Tuskegee Institute in Alabama and the Tuskegee Agricultural Experiment Station. In 1906, he designed the 'Jessup Wagon' to bring information and demonstrations to farmers in the Alabama country side. This later became the basis of the USDA Extension Service. In 1921, Carver appeared at the US House of Representatives Committee of Ways and Means about the peanut tariff. The United Peanut Association elected him to go and speak on their behalf. This was the beginning of his life as a folk hero. In 1935, he was appointed Collaborator, Mycology and Plant Disease Survey, Bureau of Plant Industry, USDA.
During his first 20 years at Tuskegee, Dr. Carver produced agricultural products which helped create a demand for crops other than cotton in the south. From peanuts, over 300 products including: milk, cheese, cream, coffee, plastics, paper, wood stains, flour, soap, linoleum, cooking oils, cosmetics, and medicinal massaging oils. From sweet potatoes over 118 products including: starch, tapioca, mock coconuts, molasses, breakfast foods, feed for livestock, dyes, flour, vinegar, ink, and synthetic rubber. From soybeans: flours, coffee, cheese, sauce, bisque for ice cream, oil, chick food, soup mixtures, bran, and stock food. From waste and native materials: rugs, tablerunners, table mats, scarfs, fuel briquettes, floor mats, synthetic marble, wallboard, wood veneers from yucca and Florida palm, vegetable dyes, etc. From cotton: paving blocks, cordage, paper, fiber for rope, and many other products.
U.S. Department of Agriculture |
Humans reportedly erode soil 100 times faster than nature, an astonishing new study revealed.
Through activities such as logging and the cutting down of native forests to make way for agricultural land, we are doing damage that would normally occur over thousands of years in just a matter of decades.
“Soils fall apart when we remove vegetation,” study co-author Paul Bierman said in a statement, “and then the land erodes quickly.”
“Earth doesn’t create that precious soil for crops fast enough to replenish what the humans took off,” researcher and geologist Dylan Rood added. “It’s a pattern that is unsustainable if continued.”
Read the full article here. |
Green frogs are relatively large frogs, 6 - 9 cm in length. They can be distinguished from the similar bullfrog by the ridges that run down each side of their back.
To determine the sex of the green frog, look at its eardrum - if it is significantly larger than its eye it's a male, if it's the same size as its eye, it's a female. During the breeding season, you can also tell the males by their yellow throats.
(Please note — these photos are unverified images submitted by members of the CWF Photo Club.)
Habitat: Tolerant of a wide range of habitats, green frogs can be found even in urban areas provided there is a permanent source of water. Their preference is for the weedy areas of warm ponds, lakes, and shallow marshes. Farm ponds are generally ideal habitat for green frogs as they tend to be deep enough to provide a year-round water supply that doesn't freeze to the bottom in winter.
Diet: Green frogs are primarily carnivores and eat a wide variety of insects and other invertebrates from both land and water, such as slugs, snails, crayfish, spiders, flies, caterpillars, butterflies, and moths.
Green frogs hide their eggs among wetland plants and pond debris. These eggs hatch into tadpoles and it takes two years to develop into adult frogs. In order for the tadpoles to survive to adulthood, the pond must provide an over-wintering area. Therefore, to provide adequate habitat for green frogs, at least one section of the pond must be below the frost line (generally greater than 2 metres in depth).Threats and What You Can Do:
All frogs are very sensitive to chemical pollutants, so the use of chemical fertilizers and pesticides should be avoided in areas surrounding green frog habitat. A buffer of native vegetation around the pond will help to filter off some of the existing contaminants before they reach the water. A diversity of plants surrounding and in the pond provides ideal habitat for frogs. Submerged plants offer sites for egg-laying and cover for tadpoles. Adults and small frogs benefit from the cover of emergent plants around the edges of the pond. Ideally, plants should be native to the area.
By providing the proper habitat for green frogs you will be benefiting our amphibian populations that have been under increasing pressure from habitat loss and pollution. In return, these creatures will do their part in controlling many of the pest insects that may invade your garden.
More on this Species: |
Chapter 1: What are solar radiation data?
The earth receives a vast amount of energy from the sun in the form of solar radiation. If we converted to usable energy just 0.2% of the solar radiation that falls on our nation, we would meet the energy demand of the entire United States. A variety of solar energy technologies are being developed to harness the sun's energy, including:
Fig. 1: These technologies convert sunlight into usable forms of energy.
"The more accurately we know the solar resource, the better we can optimize the system. Therefore, accurate solar radiation data are an important factor in solar system design."
--David F. Menicucci, Sandia National Laboratories
To minimize energy consumption, heating and air-conditioning engineers also use solar radiation data to select building configurations, orientations, and air-conditioning systems. Because energy costs are a significant expense in building ownership, an energy-efficient design can significantly reduce the life-cycle cost of a building.
The amount of solar radiation received changes throughout the day and year due to weather patterns and the changing position of the sun, and solar radiation data reflect this variability. By knowing the variability, we can size storage systems so they can provide energy at night and during cloudy periods. For technologies with no energy storage, we can evaluate load matching by comparing the profile of the available solar radiation throughout the day with a profile of the energy required by the load. Solar radiation data also help determine the best geographic locations for solar energy technologies. Other factors being equal, a site receiving more solar radiation will be more economical.
Fig. 2: Because of absorption and scattering by the atmosphere, the spectral distribution of solar radiation outside the atmosphere differs significantly from that on earth. Also, the spectral distribution on earth changes throughout the day and year and is influenced by location, climate, and atmospheric conditions. Consequently, the percentage of energy that is composed of UV, visible, or near-infrared radiation, or portions thereof, also varies by location, time of day, and year.
Table of Contents |
Archimedes, (born c. 287 bce, Syracuse, Sicily [Italy]—died 212/211 bce, Syracuse), the most-famous mathematician and inventor in ancient Greece. Archimedes is especially important for his discovery of the relation between the surface and volume of a sphere and its circumscribing cylinder. He is known for his formulation of a hydrostatic principle (known as Archimedes’ principle) and a device for raising water, still used in developing countries, known as the Archimedes screw.
Archimedes probably spent some time in Egypt early in his career, but he resided for most of his life in Syracuse, the principal Greek city-state in Sicily, where he was on intimate terms with its king, Hieron II. Archimedes published his works in the form of correspondence with the principal mathematicians of his time, including the Alexandrian scholars Conon of Samos and Eratosthenes of Cyrene. He played an important role in the defense of Syracuse against the siege laid by the Romans in 213 bce by constructing war machines so effective that they long delayed the capture of the city. When Syracuse eventually fell to the Roman general Marcus Claudius Marcellus in the autumn of 212 or spring of 211 bce, Archimedes was killed in the sack of the city.
Far more details survive about the life of Archimedes than about any other ancient scientist, but they are largely anecdotal, reflecting the impression that his mechanical genius made on the popular imagination. Thus, he is credited with inventing the Archimedes screw, and he is supposed to have made two “spheres” that Marcellus took back to Rome—one a star globe and the other a device (the details of which are uncertain) for mechanically representing the motions of the Sun, the Moon, and the planets. The story that he determined the proportion of gold and silver in a wreath made for Hieron by weighing it in water is probably true, but the version that has him leaping from the bath in which he supposedly got the idea and running naked through the streets shouting “Heurēka!” (“I have found it!”) is popular embellishment. Equally apocryphal are the stories that he used a huge array of mirrors to burn the Roman ships besieging Syracuse; that he said, “Give me a place to stand and I will move the Earth”; and that a Roman soldier killed him because he refused to leave his mathematical diagrams—although all are popular reflections of his real interest in catoptrics (the branch of optics dealing with the reflection of light from mirrors, plane or curved), mechanics, and pure mathematics.
According to Plutarch (c. 46–119 ce), Archimedes had so low an opinion of the kind of practical invention at which he excelled and to which he owed his contemporary fame that he left no written work on such subjects. While it is true that—apart from a dubious reference to a treatise, “On Sphere-Making”—all of his known works were of a theoretical character, his interest in mechanics nevertheless deeply influenced his mathematical thinking. Not only did he write works on theoretical mechanics and hydrostatics, but his treatise Method Concerning Mechanical Theorems shows that he used mechanical reasoning as a heuristic device for the discovery of new mathematical theorems.
There are nine extant treatises by Archimedes in Greek. The principal results in On the Sphere and Cylinder (in two books) are that the surface area of any sphere of radius r is four times that of its greatest circle (in modern notation, S = 4πr2) and that the volume of a sphere is two-thirds that of the cylinder in which it is inscribed (leading immediately to the formula for the volume, V = 4/3πr3). Archimedes was proud enough of the latter discovery to leave instructions for his tomb to be marked with a sphere inscribed in a cylinder. Marcus Tullius Cicero (106–43 bce) found the tomb, overgrown with vegetation, a century and a half after Archimedes’ death.
Test Your Knowledge
April Showers to March’s Lions and Lambs
Measurement of the Circle is a fragment of a longer work in which π (pi), the ratio of the circumference to the diameter of a circle, is shown to lie between the limits of 3 10/71 and 3 1/7. Archimedes’ approach to determining π, which consists of inscribing and circumscribing regular polygons with a large number of sides, was followed by everyone until the development of infinite series expansions in India during the 15th century and in Europe during the 17th century. That work also contains accurate approximations (expressed as ratios of integers) to the square roots of 3 and several large numbers.
On Conoids and Spheroids deals with determining the volumes of the segments of solids formed by the revolution of a conic section (circle, ellipse, parabola, or hyperbola) about its axis. In modern terms, those are problems of integration. (See calculus.) On Spirals develops many properties of tangents to, and areas associated with, the spiral of Archimedes—i.e., the locus of a point moving with uniform speed along a straight line that itself is rotating with uniform speed about a fixed point. It was one of only a few curves beyond the straight line and the conic sections known in antiquity.
On the Equilibrium of Planes (or Centres of Gravity of Planes; in two books) is mainly concerned with establishing the centres of gravity of various rectilinear plane figures and segments of the parabola and the paraboloid. The first book purports to establish the “law of the lever” (magnitudes balance at distances from the fulcrum in inverse ratio to their weights), and it is mainly on the basis of that treatise that Archimedes has been called the founder of theoretical mechanics. Much of that book, however, is undoubtedly not authentic, consisting as it does of inept later additions or reworkings, and it seems likely that the basic principle of the law of the lever and—possibly—the concept of the centre of gravity were established on a mathematical basis by scholars earlier than Archimedes. His contribution was rather to extend those concepts to conic sections.
Quadrature of the Parabola demonstrates, first by “mechanical” means (as in Method, discussed below) and then by conventional geometric methods, that the area of any segment of a parabola is 4/3 of the area of the triangle having the same base and height as that segment. That is, again, a problem in integration.
The Sand-Reckoner is a small treatise that is a jeu d’esprit written for the layman—it is addressed to Gelon, son of Hieron—that nevertheless contains some profoundly original mathematics. Its object is to remedy the inadequacies of the Greek numerical notation system by showing how to express a huge number—the number of grains of sand that it would take to fill the whole of the universe. What Archimedes does, in effect, is to create a place-value system of notation, with a base of 100,000,000. (That was apparently a completely original idea, since he had no knowledge of the contemporary Babylonian place-value system with base 60.) The work is also of interest because it gives the most detailed surviving description of the heliocentric system of Aristarchus of Samos (c. 310–230 bce) and because it contains an account of an ingenious procedure that Archimedes used to determine the Sun’s apparent diameter by observation with an instrument.
Method Concerning Mechanical Theorems describes a process of discovery in mathematics. It is the sole surviving work from antiquity, and one of the few from any period, that deals with this topic. In it Archimedes recounts how he used a “mechanical” method to arrive at some of his key discoveries, including the area of a parabolic segment and the surface area and volume of a sphere. The technique consists of dividing each of two figures into an infinite but equal number of infinitesimally thin strips, then “weighing” each corresponding pair of these strips against each other on a notional balance to obtain the ratio of the two original figures. Archimedes emphasizes that, though useful as a heuristic method, this procedure does not constitute a rigorous proof.
On Floating Bodies (in two books) survives only partly in Greek, the rest in medieval Latin translation from the Greek. It is the first known work on hydrostatics, of which Archimedes is recognized as the founder. Its purpose is to determine the positions that various solids will assume when floating in a fluid, according to their form and the variation in their specific gravities. In the first book various general principles are established, notably what has come to be known as Archimedes’ principle: a solid denser than a fluid will, when immersed in that fluid, be lighter by the weight of the fluid it displaces. The second book is a mathematical tour de force unmatched in antiquity and rarely equaled since. In it Archimedes determines the different positions of stability that a right paraboloid of revolution assumes when floating in a fluid of greater specific gravity, according to geometric and hydrostatic variations.
Archimedes is known, from references of later authors, to have written a number of other works that have not survived. Of particular interest are treatises on catoptrics, in which he discussed, among other things, the phenomenon of refraction; on the 13 semiregular (Archimedean) polyhedra (those bodies bounded by regular polygons, not necessarily all of the same type, that can be inscribed in a sphere); and the “Cattle Problem” (preserved in a Greek epigram), which poses a problem in indeterminate analysis, with eight unknowns. In addition to those, there survive several works in Arabic translation ascribed to Archimedes that cannot have been composed by him in their present form, although they may contain “Archimedean” elements. Those include a work on inscribing the regular heptagon in a circle; a collection of lemmas (propositions assumed to be true that are used to prove a theorem) and a book, On Touching Circles, both having to do with elementary plane geometry; and the Stomachion (parts of which also survive in Greek), dealing with a square divided into 14 pieces for a game or puzzle.
Archimedes’ mathematical proofs and presentation exhibit great boldness and originality of thought on the one hand and extreme rigour on the other, meeting the highest standards of contemporary geometry. While the Method shows that he arrived at the formulas for the surface area and volume of a sphere by “mechanical” reasoning involving infinitesimals, in his actual proofs of the results in Sphere and Cylinder he uses only the rigorous methods of successive finite approximation that had been invented by Eudoxus of Cnidus in the 4th century bce. These methods, of which Archimedes was a master, are the standard procedure in all his works on higher geometry that deal with proving results about areas and volumes. Their mathematical rigour stands in strong contrast to the “proofs” of the first practitioners of integral calculus in the 17th century, when infinitesimals were reintroduced into mathematics. Yet Archimedes’ results are no less impressive than theirs. The same freedom from conventional ways of thinking is apparent in the arithmetical field in Sand-Reckoner, which shows a deep understanding of the nature of the numerical system.
In antiquity Archimedes was also known as an outstanding astronomer: his observations of solstices were used by Hipparchus (flourished c. 140 bce), the foremost ancient astronomer. Very little is known of this side of Archimedes’ activity, although Sand-Reckoner reveals his keen astronomical interest and practical observational ability. There has, however, been handed down a set of numbers attributed to him giving the distances of the various heavenly bodies from Earth, which has been shown to be based not on observed astronomical data but on a “Pythagorean” theory associating the spatial intervals between the planets with musical intervals. Surprising though it is to find those metaphysical speculations in the work of a practicing astronomer, there is good reason to believe that their attribution to Archimedes is correct.
Given the magnitude and originality of Archimedes’ achievement, the influence of his mathematics in antiquity was rather small. Those of his results that could be simply expressed—such as the formulas for the surface area and volume of a sphere—became mathematical commonplaces, and one of the bounds he established for π, 22/7, was adopted as the usual approximation to it in antiquity and the Middle Ages. Nevertheless, his mathematical work was not continued or developed, as far as is known, in any important way in ancient times, despite his hope expressed in Method that its publication would enable others to make new discoveries. However, when some of his treatises were translated into Arabic in the late 8th or 9th century, several mathematicians of medieval Islam were inspired to equal or improve on his achievements. That holds particularly in the determination of the volumes of solids of revolution, but his influence is also evident in the determination of centres of gravity and in geometric construction problems. Thus, several meritorious works by medieval Islamic mathematicians were inspired by their study of Archimedes.
The greatest impact of Archimedes’ work on later mathematicians came in the 16th and 17th centuries with the printing of texts derived from the Greek, and eventually of the Greek text itself, the Editio Princeps, in Basel in 1544. The Latin translation of many of Archimedes’ works by Federico Commandino in 1558 contributed greatly to the spread of knowledge of them, which was reflected in the work of the foremost mathematicians and physicists of the time, including Johannes Kepler (1571–1630) and Galileo Galilei (1564–1642). David Rivault’s edition and Latin translation (1615) of the complete works, including the ancient commentaries, was enormously influential in the work of some of the best mathematicians of the 17th century, notably René Descartes (1596–1650) and Pierre de Fermat (1601–65). Without the background of the rediscovered ancient mathematicians, among whom Archimedes was paramount, the development of mathematics in Europe in the century between 1550 and 1650 is inconceivable. It is unfortunate that Method remained unknown to both Arabic and Renaissance mathematicians (it was only rediscovered in the late 19th century), for they might have fulfilled Archimedes’ hope that the work would prove useful in the discovery of theorems. |
In this lesson there will be:
- Activities related to the parts of the body in Spanish.
- How conjugate sense verbs in Present simple.
- Complete the gaps with sense verbs.
- Writing activities about physical description.
- Adjectives to describe the personality.
- How to ask in Spanish (Interrogative pronouns) + activity.
- Verbs ser and estar + activity.
- Conjugate verbs in Present simple activity. |
January 19, 2015 by dragonflytraining
“This report reviews over 200 pieces of research to identify the elements of teaching with the strongest evidence of improving attainment.”
“It finds some common practices can be harmful to learning and have no grounding in research. Specific practices which are supported by good evidence of their effectiveness are also examined and six key factors that contribute to great teaching are identified.”
What has the strongest evidence?
- Teachers’ content knowledge (strong evidence): teachers must have a deep knowledge of the subjects they teach and, crucially, must understand how students think about the subject and identify students’ common misconceptions.
- Quality of instruction (strong evidence): this includes strategies such as effective questioning and assessment…
View original post 637 more words |
One, now in human testing, uses gene therapy to help the immune system better recognize specific kinds of cancer cells. Another, already used to eradicate tumors in mice, uses gene therapy to alter stem cells, which in turn make immune cells that combat the specific cancer -- a treatment that would last a lifetime.
Baltimore and Rosenberg are both using gene therapy to mobilize T cells against cancer. First, they remove T cells from a patient who has recovered from, for example, a melanoma tumor. From these cells, they clone a gene whose protein product, a T cell receptor, has a strong affinity for a melanoma antigen. Then they construct a virus that can deliver this gene to other T cells.
Baltimore’s lab research has gone beyond T cells to the immune cells’ precursor, stem cells. Throughout life, stem cells in the bone marrow replenish blood cells, including those involved in the immune system like T cells. Because stem cells are continuously replenishing the immune system, giving them a gene that combats cancer would mean “a life-long supply of tumor-specific T cells,” says Baltimore. Using the stem cell technique in mice with existing tumors (while providing mice with supplements of another type of immune cell) leads mice to completely destroy their tumors, says Lili Yang, a research in Baltimore’s lab.
Baltimore won the Nobel prize in medicine in 1975 for his work on the kind of viruses used in gene therapy, and is now working on developing stem cell-targeted viruses. |
Successive cultivation of different crops in a specified order on the same fields. Some rotations are designed for high immediate returns, with little regard for basic resources. Others are planned for high continuing returns while protecting resources. A typical scheme selects rotation crops from three classifications: cultivated row crops (e.g., corn, potatoes), close-growing grains (e.g., oats, wheat), and sod-forming, or rest, crops (e.g., clover, clover-timothy). In general, cropping systems should include deep-rooting legumes. In addition to the many beneficial effects on soils and crops, well-planned crop rotations make the farm a more effective year-round enterprise by providing more efficient handling of labour, power, and equipment, reduction in weather and market risks, and improved ability to meet livestock requirements.
Learn more about crop rotation with a free trial on Britannica.com.
Usually, an aircraft used for dusting or spraying large acreages with pesticides, though other types of dusters are also employed. Aerial spraying and dusting permit prompt coverage of large areas at the moment when application of pesticide is most effective and avoid the need for wheeled vehicles that might damage crops. The technique was greatly improved in the 1960s with the development of ultra-low-volume applicators, in which concentrated pesticides are distributed in extremely small amounts. Seealso spraying and dusting.
Learn more about crop duster with a free trial on Britannica.com.
Crop-lien system was a way for farmers to get credit. After the crop was harvested they would use it to pay back their loan. This is different from sharecropping.
In the postwar South, many former slaves remained as farmers. Not having any money, they could not buy land but instead worked a small portion of a large parcel owned by a single person. Many former slaves were tenants of the same landowner and each had their own section of farm to work on independently, hence the term "sharecropper." In exchange for working on the owner's land, the sharecropper would give some of his harvest as payment.
Also having hardly any possessions, the sharecroppers bartered with merchants to loan them supplies essential for farming. The deal was similar to the land owners': a percentage of the harvest would be given to the merchant to pay for the supplies. This system would have worked if the merchant lenders charged reasonable interest rates. However, racism was a factor in that the merchant's interest rates were impossible for the sharecroppers to pay off. In addition, when the bank gave someone a loan, it was allowed to dictate the crop that a farmer grew. Therefore, the banker for a certain area would tell everyone to grow the same crop and with an increased competition it was even harder for the farmers to sell their goods. It was a constant cycle of debt.
(A farmer would farm someone else's land and give a portion of his crops to the land owner (Sharecropping) with a hope of someday saving up enough to buy the land from the owner. A Sharecropper would have to buy his own equipment and seed with yet more portions of his crop, and usually earned barely enough to survive, falling deeper and deeper into debt.) |
Imagine drinking from a cup without a bottom. How about taking a bath in a tub without a drain plug? Now, imagine living like this day after day. This was the plight of those who once populated the nearly bone dry land of Wupatki, which hoarded every drop of water as soon as it touched ground. Not far from the Sunset Crater, the Wupatki Pueblo stands tall against the painted skies, and speaks of a time when resourcefulness and total communion with nature were the only true methods of survival!
In the Hopi language, Wupatki means “œit was cut long”. A definite understatement, considering the more than 800 ruins scattered around the 35,000 plus acres of Wupatki National Monument’s vast landscape. After the eruption of Sunset Volcano in about 1100, the ancient people migrated toward this area. The Sinagua, Kayenta Anasazi, and Cohonina peoples converged to create a thriving, peaceful community amidst the infinite beauty of Arizona’s unsettled ancient landscape.
Combine lava flows and volcanic ash with some very hot, very dry climate, and you get living conditions that did not cater to the thirsty. Even today, the Wupatki Pueblo is lucky to get 8″ of annual rainfall. The ancient settlers relied on annual snow and rainfalls as their main water supply. The Sinagua people were named after the Sierra Sin Agua (mountain without water), coined by Spanish explorers who, centuries later, found the San Francisco Peaks to be lacking the agua department!
Necessity truly is the mother of invention, however, and nothing confirms this more than the creative methods developed by the Ancient Pueblo Peoples to catch every precious drop of water available. From studying climate and seasons, and constructing catchments and dams, to crafting pottery and flasks, and devising methods for growing crops, like corn and squash, without irrigation, their intelligence and perseverance ensured that they would not wilt under the sweltering desert sun.
Not only adept in skills of survival, they were also consummate architects. Using the very dirt beneath their feet, they constructed efficient, sturdy housing known as the pueblos. The largest of these, the Wupatki Pueblo, boasted 100 rooms, a lookout tower, a community meeting room, and a ceremonial court. From the confines of this fortress, the Ancient Pueblo People developed a thriving agricultural and trading center.
And then they vanished. Without so much as note. Whether the Wupatki settlers left one by one or in large groups, many theories exist as to the reasoning for their disappearance from this thriving settlement around the late 1200′s. Climate changes could have made survival all but impossible. Winds of hope for a more promising future elsewhere may have blown through the open windows. Perhaps, as the Hopi Tribe believes, they may have lost focus on what is important, failed to lead moral and productive lives, and as a result suffered many social and ecological catastrophes, forcing them to move away.
Several centuries later, in 1857, by fate, or a simple change in direction, Captain Lorenzo Sitgreaves, and his band of exploratory gents stumbled upon the ruins. During a mission to chart the Zuni and Colorado River territories, they came face to face with a mysterious past in the form of the abandoned dwellings of Wupatki. Less than a century later, in 1924, the Wupatki National Monument was created to protect the Wupatki and Citadel pueblos. In 1966, Wupatki was listed on the National Register of Historic Places. Today, more than 2600 archaeological sites have been designated within the Monument. Some of the ruins remain inaccessible; however, the Wupatki Pueblo Trail provides opportunity for extensive exploration of the largest of these ruins.
While the Sinagua, and other native peoples, may have walked off into the historical sunset, becoming Hisatsinom (defined in Hopi language as ‘people of long ago’), the Hopi believe themselves to be a direct ascendants of this mysterious gathering of people, who contributed to the genetic and cultural makeup of the Hopi tribe, and continually use knowledge of this fascinating history to learn and grow as a people today.
*Above photos on this page: Creative Commons. |
Lions are one of the most iconic animals on the planet. They play starring roles in the art of hundreds of cultures, in literature from history books to fairytales and are, of course, are one of the biggest draws of tourists to the African continent.
However, they are disappearing from the wild at an astonishingly rapid rate.
According to Panthera, lions have disappeared from 90 percent of their historic range due to habitat loss, hunting and poaching, retaliatory killings by livestock owners, loss of prey and other factors. "Just over a century ago, there were more than 200,000 wild lions living in Africa. Today, there are only about 20,000; lions are extinct in 26 African countries."
The population count from the IUCN Red List is slightly more optimistic, but not much: They estimate there are 20,000 to 39,000 lions left in the wild.
Though lions are such a big part of the human consciousness across the planet, we are at risk of the species entirely disappearing from the grasslands where they roam. This fact surprises many people, including those who love lions. These big cats are part of a much bigger ecosystem, one in which humans play a significant role. That role can be shifted from one that is causing lion populations to dwindle toward extinction, to one that creates strategies for coexisting with and protecting this important and magnificent predator.
If you'd like to learn more about lion conservation and how you can help, check out these groups:
Editor's note: This file has been updated since it was originally published in May 2015. |
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An open economy is an economy in which there are economic activities between the domestic community and outside (people, and even businesses, can trade in goods and services with other people and businesses in the international community, and funds can flow as investments across the border). Trade can take the form of managerial exchange, of technology transfers, and of all kinds of goods and services. (However, certain exceptions exist that cannot be exchanged - the railway services of a country, for example, cannot be traded with another country to avail this service, a country has to produce its own.) This contrasts with a closed economy in which international trade and finance cannot take place.
The act of selling goods or services to a foreign country is called exporting. The act of buying goods or services from a foreign country is called importing. Together exporting and importing are collectively called international trade.
There are a number of economic advantages for citizens of a country with an open economy. One primary advantage is that the citizen consumers have a much larger variety of goods and services from which to choose. Additionally, consumers have an opportunity to invest their savings outside of the country.
If a country has an open economy, that country's spending in any given year need not equal its output of goods and services. A country can spend more money than it produces by borrowing from abroad, or it can spend less than it produces and lend the difference to foreigners. As of 2014[update] no totally closed economy exists.
Economic models of an open economy
= The basic model =
In a closed economy, all output is sold domestically, and expenditure is divided into three components: consumption, investment, and government purchases.
Y = C + I + G
where Y is the total output, C is the total consumption, I is the total investment and G is the total government expenditure. In an open economy, some output is sold domestically and some is exported to be sold abroad. We can divide expenditure on an open economy’s output Y into four components: Cd, consumption of domestic goods and services, Id, investment in domestic goods and services, Gd, government purchases of domestic goods and services, X, exports of domestic goods and services. The division of expenditure into these components is expressed in the identity
Y = Cd + Id + Gd + X.
The sum of the first three terms, Cd + I d + Gd, is domestic spending on domestic goods and services. The fourth term, X, is foreign spending on domestic goods and services(the value of exports). Since total domestic spending is a sum of spending on domestic as well as foreign goods and services, we can say that,
C = Cd + Cf, I = I d + I f, G = Gd + G f.
We substitute these three equations into the identity above: Y = (C − Cf ) + (I − I f ) + (G − G f ) + X. We can rearrange to obtain
Y = C + I + G + X − (Cf + I f + G f ).
The sum of domestic spending on foreign goods and services (Cf + I f + G f ) is expenditure on imports (IM ). We can thus write the national income accounts identity as
Y = C + I + G + X − MI.
Since the value of total imports is a part of domestic spending and it is not a part of domestic output, it is subtracted from the total output.This gives us the value of Net Exports (NX = X − IM ), the identity becomes
Y = C + I + G + NX.
In closed economy: National savings= Investment. Closed economy countries can increase its wealth only by accumulating new capital.
If Bold textoutput exceeds domestic spending s, we export the difference: net exports are positive. If output falls short of domestic spending, we import the difference: net exports are negative.
International Capital Flows and Trade Balance
Begin with the identity
Y = C + I + G + NX.
Subtract C and G from both sides to obtain
Y − C − G = I + NX.
Y − C − G is national saving S, which equals the sum of private saving, Y − T − C, and public saving, T − G, where T stands for taxes. Therefore,
S = I + NX.
Subtracting I from both sides of the equation, we can write the national income accounts identity as
S − I = NX.
This shows that economy's net exports must be equal to the difference between savings and investment. Another name for net exports is the trade balance, as it tells us the difference between imports and exports from being equal.
The left-hand side of the identity is the difference between domestic saving and domestic investment, S − I,known as net capital outflow.Net capital outflow is equal to the amount that domestic residents are lending abroad minus the amount that foreigners are lending to home country.If net capital outflow is positive, the economy’s saving exceeds its investment, and lending the excess to foreigners. If the net capital outflow is negative, the economy is experiencing a capital inflow: investment exceeds saving, and the economy is financing this extra investment by borrowing from abroad.
The national income accounts identity shows that net capital outflow always equals the trade balance. That is, Net Capital Outflow = Trade Balance
S − I = NX.
If S − I and NX are positive, we have a trade surplus. In this case,since our exports are higher than our imports, we are net lenders in world financial markets. If S − I and NX are negative, we have a trade deficit. In this case, we are importing more goods than we are exporting.And hence we are net borrowers in the world markets. If S − I and NX are exactly zero, we are said to have balanced trade because the value of imports exactly equals the value of our exports.
Capital Mobility and World Interest Rates under Open Economy
In case of a small open economy, we assume perfect capital mobility. By "small" we mean that an economy has very small share in the world markets. It has a negligible effect on interest rate. By perfect capital mobility, we mean that residents of a country have full access to goods and services and specially financial markets of the world. Because of this assumption of perfect capital mobility, the interest rate in our small open economy, r, must equal the world interest rate say, r*, the real interest rate prevailing in world financial markets: r = r*. This means that people in this small open economy will never borrow at more than r rate in home country.They will shift to international markets to borrow or invest, in case r > r*. Thus, we can say that, the interest rates in a small open economy are determined by the world markets. World interest rate (r*), on the other hand is determined by equilibrium of world saving and world investment.
2. R. Dornbusch, S.Fischer, Macroeconomics, 6ed., pp 87–145 |
The world's population is forecast to hit 7 billion in 2011, the vast majority of its growth coming in developing and, in many cases, the poorest nations.
The world population is the total number of living humans on Earth. As of today, it is estimated to number 7.123 billion by the United States Census Bureau (USCB). The USCB estimates that the world population exceeded 7 billion on March 12, 2012. According to a separate estimate by the United Nations Population Fund, it reached this milestone on October 31, 2011.
The world population has experienced continuous growth since the end of the Great Famine and the Black Death in 1350, when it stood at around 370 million. The highest rates of growth – global population increases above 1.8% per year – were seen briefly during the 1950s, and for a longer period during the 1960s and 1970s. The growth rate peaked at 2.2% in 1963, then declined to below 1.1% by 2012. Total annual births were highest in the late 1980s at about 138 million, and are now expected to remain essentially constant at their 2011 level of 134 million, while deaths number 56 million per year, and are expected to increase to 80 million per year by 2040. Poverty
Human geography is one of the two major sub-fields of the discipline of geography. Human geography is a branch of the social sciences that studies the world, its people, communities and cultures with an emphasis on relations of and across space and place. Human geography differs from physical geography mainly in that it has a greater focus on studying human activities and is more receptive to qualitative research methodologies. As a discipline, human geography is particularly diverse with respect to its methods and theoretical approaches to study.
Geographical knowledge, both physical and social, has a long history. In the history of geography, geographers have often recorded and described features of the Earth that might now be considered the remit of human, rather than physical, geographers. For example Hecataeus of Miletus, a geographer and historian in ancient Greece, described inhabitants of the ancient world as well as physical features. Earth
Environmental science is a multidisciplinary academic field that integrates physical and biological sciences, (including but not limited to ecology, physics, chemistry, zoology, mineralogy, oceanology, limnology, soil science, geology, atmospheric science, and geography) to the study of the environment, and the solution of environmental problems. Environmental science provides an integrated, quantitative, and interdisciplinary approach to the study of environmental systems.
Related areas of study include environmental studies and environmental engineering. Environmental studies incorporates more of the social sciences for understanding human relationships, perceptions and policies towards the environment. Environmental engineering focuses on design and technology for improving environmental quality in every aspect. Environmental scientists work on subjects like the understanding of earth processes, evaluating alternative energy systems, pollution control and mitigation, natural resource management, and the effects of global climate change. Environmental issues almost always include an interaction of physical, chemical, and biological processes. Environmental scientists bring a systems approach to the analysis of environmental problems. Key elements of an effective environmental scientist include the ability to relate space, and time relationships as well as quantitative analysis. Social Issues
Health Medical Pharma |
Yellow Pitcher Plant
North Carolina is a great place to live or visit if you enjoy carnivorous plants! Yellow Pitcher Plants are one of several carnivorous plants that are native to North Carolina.
What is a Yellow Pitcher Plant? Yellow Pitcher Plants have tall, trumpet-shaped yellow-green leaves that are commonly a foot or two in length, but can reach nearly 4 feet. The uppermost part of the leaf is expanded into a “lid” that covers the tube formed by the rest of the leaf. You’ll commonly see several of the leaves together.
How do Yellow Pitcher Plants eat? Insects are attracted to the Pitcher Plant’s leaves and the nectar it provides along the upper region of the leaves. The nectar contains intoxicating chemicals, however, and the insects stumble down into the plant as they follow downward pointing hairs. Eventually they slip on the slippery surface of the leaf and fall into a pool of digestive chemicals at the base. The plant then absorbs the nutrients from the insect as it is broken down.
What is the range of the Yellow Pitcher Plant? These plants are native to the coastal regions of the Carolinas, Alabama, Georgia, and Florida. In North Carolina, the plants are more widespread and are also found in the piedmont and mountain regions.
We’ve got Pitcher Plants growing in the rain garden area of our Nature Neighborhood Garden at Prairie Ridge. Come on out and see them! You just might have a chance to see the plant capture its prey!
Find out more about the natural happenings at Prairie Ridge at our What Time is it in Nature Archive. |
The coral tooth fungus (Hericium coralloides) has been described as our most beautiful species of fungus (2). It is a member of the group called 'tooth fungi', because their fruit bodies produce tooth-like spines (6). These spines serve the same function (producing spores) as the more familiar gills found on mushrooms (2). The coral tooth fungus is pale whitish in colour, and has branches from which long, fine spines hang down like icicles (7). When young, the species has a more 'knobbly' appearance and is said to resemble a coral (2).
WARNING: many species of fungus are poisonous or contain chemicals that can cause sickness. Never pick and eat any species of fungus that you cannot positively recognise or are unsure about. Some species are deadly poisonous and can cause death within a few hours if swallowed.
Fungi are neither plants nor animals but belong to their own kingdom. They are unable to produce their own food through the process of photosynthesis, as plants do; instead, they acquire nutrients from living or dead plants, animals, or other fungi, as animals do. In many larger fungi (lichens excepted) the only visible parts are the fruit bodies, which arise from a largely unseen network of threads called 'hyphae'. These hyphae permeate the fungus's food source, which may be soil, leaf litter, rotten wood, dung, and so on, depending on the species. (5). The coral tooth fungus has a relatively short lifespan because the logs on which it is found often rot after just a few years (2). Remarkably, considering its rarity, this fungus seems to be able to keep other species of fungi at bay and gain sole access to host logs (4).
The coral tooth fungus is uncommon and local in England, occurring in the south and the east (6). It is known from around seven sites in the New Forest (2). It is not known elsewhere in the British Isles and is rare throughout Europe and North America. It is a Red-List species in the UK, Germany, Denmark, Poland, Spain and the Netherlands (4).
As yet we do not know enough about the ecology of the coral tooth fungus to understand why it appears to be so rare (6). Possibly it is because the logs on which it lives rot so rapidly that it is difficult for the fungus to find a continuous supply of suitable dead wood. In many woodlands, particularly where they are commercially managed, fallen dead wood is removed (4).
Although the coral tooth fungus is possibly one of our most endangered fungi, it has not been incorporated into the UK Biodiversity Action Plan as a priority species (2). As is the case with most of our threatened fungi, we must discover more about the ecology of this species if we are to be in a position to conserve it (2).
Metabolic process characteristic of plants in which carbon dioxide is broken down, using energy from sunlight absorbed by the green pigment chlorophyll. Organic compounds are made and oxygen is given off as a by-product.
Microscopic particles involved in both dispersal and reproduction. They comprise a single or group of unspecialised cells and do not contain an embryo, as do seeds.
Embed this ARKive thumbnail link ("portlet") by copying and pasting the code below. |
Flicker is common characteristic of most artificial (man-made) light sources, and another way that artificial light is different than natural light (which has no flicker). Flicker is due to the way light sources are powered and depends upon the type of ‘lamp’ as well as the electronics used to drive the light-source. The electricity which comes out of a regular wall socket alternates at 50 or 60 Hz (AC = alternating current) which means the power feeding most lights is cycling on/off 100 or 120 times a second. As a result, many light sources flicker at 100 or 120 Hz, since they have power twice in every cycle. Almost all artificial light sources are associated with flicker, including TV screens and computer monitors. Flicker is a known cause of headaches and eye strain and has also been tied to reduced concentration and visual performance. Studies show that some individuals are more sensitive to flicker than others. In addition to headaches and eye-strain, flicker can increase heart rate, induce dizziness or nausea and even trigger seizures. Unfortunately, the commonly used flicker metrics don’t provide enough information to judge the quality of a light source. Here we describe the health impacts of flicker, provide measurements of common light sources (incandescent, LED, fluorescent), and discuss what makes some artificial light sources more disruptive than others.
Documented effects of Light Flicker from various sources of artificial light (source).
Flicker refers to the change in the intensity of the light source as a function of time. In simple terms, the two things which matter are (1) how much the light intensity varies (flicker amplitude) and (2) how many times per second the light is flashing or cycling (flicker frequency). The two most common flicker metrics (flicker percent and flicker index) are a measure of (1) how much the intensity of the light varies. As you would expect the higher the number, the more the intensity or amplitude of the light varies (the worse the flicker). Old fashioned incandescent bulbs flicker at 100-120 Hz but with less than a ~10% variation in intensity/amplitude which is generally not enough to cause discomfort. Equally important is (2) the rate at which the light varies (how many flashes per second). As it turns out the slower the light cycles or flashes the more disruptive the flicker! First generation fluorescents (with magnetic ballasts) flickered at 100-120 Hz, leading to complaints of headaches and eyestrain. Newer fluorescents (with electronic ballasts) cycle at 20-60 kHz (>100x faster) which is thought to be outside the range of human perception – but most still have some 120 Hz oscillation. Poorly designed LED lights flicker at 100-120 Hz and can be quite disruptive, while higher quality LED lights flicker at lower amplitude and much higher frequencies. In an extreme case of disruptive flicker, a 1997 Pokémon cartoon showed flashes at 10 Hz (10 cycles/second) causing seizures in children with no prior history of epilepsy. Humans can see lights flicker up to 60-100 Hz (60-100 cycles per second) which is called the critical fusion frequency, but negative health effects have been documented at frequencies up to 200 Hz and there is speculation of impacts at even higher frequencies. Net-net the lower the flicker percent (or flicker index) and the higher the flicker frequency, the less disruptive the light!
Not all artificial light sources are created equal. Most cheap LED bulbs have moderate 120 Hz flicker. With proper electronics it is possible to design and build a light source with no flicker!
Guide to measuring Light Flicker:
(1) amplitude of the flicker (how much the intensity varies per cycle):
– Flicker Index = (Area 1)/(Area 1 + Area 2)
– Flicker Percent = 100% × (Maximum Value – Minimum Value)/(Maximum Value + Minimum Value)
*Flicker Index of less than 0.05, and/or a Flicker Percent of less than 10% are ‘good’ (the lower the number the better)
Flicker Percent and Flicker Index are two common measurements of the magnitude or amplitude of Light Flicker. For more on measuring flicker click here.
(2) frequency of the flicker (how many times per second does the light vary):
– Flicker Frequency = # of cycles / second
*Flicker Frequency of >500 Hz is ‘good’ (the higher the frequency the better)
Comparing low frequency (120 Hz) and high frequency (850 Hz) light flicker. low frequency flicker (120 Hz) is much more disruptive than high frequency (>500 Hz) light flicker. Note that the amplitude of the flicker is the same, but due to the lower (120 Hz) frequency the red flicker is much more disruptive than the blue!
(3) flicker amplitude as a function of dimming (how flicker changes as you dim the lamp)
– Flicker Index and Flicker Percent at 50% dim and 95% dim levels
*Flicker Index and Flicker Percent should not increase dramatically as a light source is dimmed
Flicker amplitude increases with dimming for incandescent and LED bulbs, while the Flicker Frequency does not change (stays fixed at 120 Hz).
Unfortunately there is no universally accepted standard for ‘safe flicker’ (maybe ‘safe flicker’ is just an oxymoron?), but practically speaking a Flicker Percent of less than 10%, and a Flicker Index of less than 0.05 is considered ‘good’ (the lower the number the better). While most artificial light sources flicker at 120 Hz, the higher the flicker frequency the better. Frequencies above 1000 Hz thought to be imperceptible for humans (no measurable biological/physiological impact). California has proposed setting a crude threshold of no more than 30% flicker for Title 24 regulations. The IEEE (Institute of Electrical and Electronics Engineers) has published a more nuanced set of ‘recommended practices’ under IEEE 1789. The IEEE guidelines take into account both the amplitude and the frequency of the flicker, and suggest a limit of no more than 8% Flicker in Europe (at 100 Hz) and 9.6% in the US (at 120 Hz). While these thresholds are not perfect, and some people are more sensitive to flicker than others, they do provide a useful framework.
Summary of IEEE 1789 ‘Recommended Practices’ for Light Flicker. Light sources with a lower Flicker Percent and higher Flicker Frequency are less disruptive. (source of this figure).
Comparing the Light Flicker of various artificial light sources:
Additional reading and references about Light Flicker:
– Understand the lighting flicker frustration – high-level lighting industry overview on the topic of Light Flicker
– LED Lighting Flicker and Potential Health Concerns: IEEE Standard PAR1789 Update
– Potential Biological and Ecological Effects of Flickering Artificial Light
– Light Flicker from LED Lighting Systems – An Urgent Problem to Solve
– 1789-2015 – IEEE Recommended Practices for Modulating Current in High-Brightness LEDs for Mitigating Health Risks to Viewers
– Designing to Mitigate Effects of Flicker in LED Lighting: Reducing risks to health and safety |
Art & Design
Art & Design Intent
We aim to give our children the opportunity to enjoy and understand the visual arts by increasing their awareness of great artists, architects and designers in history. By following the arts process, all children will develop the skills and techniques necessary to independently create visual works. Children will be capable of expressing their personal, environmental, social or political messages through the visual arts.
The art and design projects are well sequenced to provide a coherent subject scheme that develops children’s skills and knowledge of visual elements, art forms, artists and art movements.
Projects are placed alongside other subject projects where there are opportunities for making meaningful connections. For example, Beautiful Botanicals has been placed in the same teaching sequence as the science project Plants Nutrition and Reproduction.
Where possible, projects with similar materials are spaced out to have as little strain on resources as possible. For example, in Key Stage 1, clay work is taught in different terms.
Seasons are also a consideration for the placement of art and design projects. For example, if children are required to work outdoors, these projects have been placed in either the latter part of the spring or summer term.
Early Years Foundation Stage
In Expressive Arts and Design: Creating with Materials aspect, the children will develop their drawing skills by exploring line. As part of this, they will represent the human face from observation and memory. They will explore primary colours and colour mixing which will then be developed in painting by mixing tints and shades and by using a range of tools. This will lead to the exploration of mixing secondary colours. Painting techniques, such as creating patterns, and exploring works of art will inspire their own work and the children will be introduced to a variety of media. They will investigate environmental art, for example, using ice and natural resources to create artwork.
The children will have experiences in manipulating dough, progressing onto clay to create shapes and learning a range of techniques. They will explore how to cut, tear, fold and stick paper and fabric to create collages. Threading skills will also be developed and they will be given opportunities to create large scale weavings using fabrics and recycled materials.
Key Stage 1
In Key Stage 1, each autumn term begins with the colour project Mix It. The teaching of this project in Years 1 and 2 enables children to be introduced to and then revisit colour theory and provides plentiful opportunities for children to explore primary and secondary colours.
Year 1 begins by exploring themes directly related to the children themselves, such as their facial features, the surrounding natural world and their local community. In Year 2, the projects expand children’s artistic horizons to study a more comprehensive range of artists, artistic movements and creative techniques.
Lower Key Stage 2
In Lower Key Stage 2, each autumn term begins with the colour project Contrast and Complement. In Years 3 and 4, the teaching of this project enables children to build on their previous understanding of colour and further develop their expertise by studying theory.
In Year 3, children expand their experiences to study a broader range of art forms, artists and genres. They also begin to study art from specific and diverse periods of history, including prehistoric pottery and Roman mosaics. Other genres studied in Year 3 build on previous techniques learned in Key Stage 1 and include more complex techniques in printmaking, drawing, painting and textiles.
In Year 4, children develop more specialised techniques in drawing, painting, printmaking and sculpture. They explore ways in which ancient cultures have influenced art and crafts by studying, for example, mediaeval weaving techniques and the religious significance of Islamic art.
Upper Key Stage 2
In Upper Key Stage 2, each autumn term begins with the colour project Tints, Tones and Shades. Teaching these projects in Years 5 and 6 enables children to build on their previous understanding of colour theory and develop further expertise with colour by studying tonal variations and more complex colour charts.
In Year 5, children develop and combine more complex artistic techniques in a range of genres, including drawing, painting, printmaking and sculpture. Children continue to build on their understanding of other historical periods and cultures by studying the ancient Chinese art form of taotie and the significance of the Expressionist movement.
In Year 6, children are encouraged to work more independently in projects like Environmental Artists and Distortion and Abstraction. Such projects require them to consider more conceptual representations of personal, environmental, social or political messaging. Children explore diversity in art by studying the projects Inuit and Trailblazers, Barrier Breakers.
Throughout the art and design scheme, there is complete coverage of all national curriculum programmes of study. |
- Compare and contrast non-Western and European painting. For example, explain the attitude of traditional Chinese painters towards space, the picture surface, ambiguity and inscriptions. How does this differ from paintings done by Western European painters? Provide two works of art as examples in your response.
- Compare and contrast non-Western and European architecture. Use buildings/cathedrals from Week 5 and Week 6 readings. For example, consider differences in Buddhist, Hindu, and Islamic architecture (select one) with that of Western European architecture. Consider interior and exterior space and decoration. Provide examples in your response.
Select an abstract work of art from this week’s readings, from the Heilbrunn Timeline of Art History website, or any reputable art museum site (cite the source and include an image). Is it necessary to know the title of the piece to fully appreciate the work, or any other non-representational work? Why or why not? Defend your position.
If subject matter is what is being depicted in a work of art, what is the subject of non-representational works such as Blue, Orange, Red by Mark Rothko and Autumn Rhythm by Jackson Pollock?
What is Donald Judd communicating in his piece titled 100 Untitled Works in Mill Aluminum? What do you think the content is? How does the form help the artist express the content? How does the work of Pollock and Judd differ?
Explain how you feel when viewing an artwork without representational imagery, storytelling, or explicit personal feeling. Can shapes and colors evoke emotion and interpretation?
Identify visual elements and principles of design in your analysis.
Discuss the role that public art has played in past and present society and speculate about the role it will play in the future. Use two examples of public art from Chapters 15–25 of the textbook to support your answers. Be sure to include one contemporary example and one from the past. Consider the role that socially engaged art plays in current society to address social and political concerns.
Share your art exhibit with the class by posting your submission to the discussions area. View your classmate’s exhibits and comment on their selected artworks and presentation.
In addition to sharing your exhibit, share your final thoughts about what you’ve learned and how you feel what you have learned in the class will influence your life moving forward.
- 24 days ago
Art appreciation 9-15 (5times)NOT RATED2 years ago |
Fun activity #4 is ‘Gira la botella,’ or ‘spin the bottle.’
I forget what the original purpose of this game was (as described at the conference I went to, that is), but I tweaked it to be a game to practice idioms. I find that one of the hardest parts of vocabulary acquisition is getting students to really use idioms in their speech and writing. Part of the problem is a lack of practice in seeing and using them repetitively in a meaningful context. Imagine my dismay when I found out one of my fourth-year students who had practically memorized Luis Fonsi’s song No me doy por vencido still had no idea what the expression meant. Doh! (on me, not her) I guess songs don’t cure all ills. (Did I just write that?) Anyway, back to the game…
- In a document, make a list of common idiomatic expressions for your language, expressions you want your students to be able to use in appropriate contexts spontaneously.
- When this game is chosen as a class activity, copy and paste your list into the random chooser. Run the chooser so it selects an expression. (Be sure to use the fruit machine, not typewriter, so you can remove the option after it’s used.)
- Get your students into a circle. It’s always good to have an opportunity to change things up, and get them up and moving, eh?
- Spin a bottle in the middle of a circle. You can use any bottle but for cultural effect we use a Manzanita bottle (my favorite Mexican beverage).
- When the bottle stops, the person at whom it’s pointing begins a sentence with the idiom. For example, “No me doy por vencido en la clase de matemáticas.”
- Going clockwise, the next person has to remember exactly the sentence and add a detail: “No me doy por vencido en la clase de matemáticas por la mañana.”
- The first person to forget any of the sentence is out and has to sit down. Spin the bottle again, choose a different idiom, and keep going until you’re done (or we time our game for 10 minutes).
I imagine you could use this for any vocabulary you’re targeting and it would work the same way. I particularly like idiomatic expressions because it’s such a real way to push real communicative proficiency at every level. Have fun (but I don’t recommend including kissing).
Photo credit: Mickey Del Favero |
Cytoskeleton is a three dimensional network of filamentous proteins that extend throughout the cytosol (= cytoplasmic matrix) of all eukaryotic cells.
The cytoskeleton is closely involved in many processes including cell division, growth, maintenance of cell shape, differentiation, wall deposition, movement of organelles etc.
Cytoskeleton consists of three types of elements: microtubules, microfilaments and intermediate filaments. They are visible only with the help of electron microscope. They are absent in prokaryotic cells. Microtubules and microfilaments are dynamic structures, constantly forming and disassembling.
De Robertis and Franchi (1953) first discovered microtubules in the axoplasm of nerve fibers.
They are found in the cytoplasmic matrix of all eukaryotic cells. They are also present in structures like centrioles, basal bodies, cilia or flagella, sensory hair, spindle apparatus, chromosome fibres, nerve processes, sperm tail etc. They are absent in prokaryotic cells.
Microtubules are unbranched, hollow cylinders of about 0.2 – 25, wm long. Their outer diameter is 25 nm with a core of 15 nm and a wall of 5 nm thick. The wall consists of 13 parallel proto-filaments. Each proto filament is a polymer of tubulin dimers (a – and β-tubulin). The ends of microtubules are designated as’+’ and’-‘.
The polymerization (assembly) is more rapid in + end. The site of microtubule form and growth is called microtubule organizing center (MTOC). Satellites of centrioles, kinetochores of chromosomes and basal bodies act as MTOC. At places microtubules may have lateral projections. The half life of individual microtubule is 10 minutes in non-dividing animal cells and just 20 sec. in dividing animal cells.
1. They maintain cell shape.
2. They are the structural components of centrioles, basal bodies, spindle apparatus, chromosomal fibers, cilia and flagella.
3. In term of Chromosomal fibers, they bring about anaphasic movement of Chromosome.
4. They determine the orientation of cellulose micro fibrils in cell wall.
5. They are associated with intracellular transport of organelles, vesicles and macromolecules.
6. In chromatophores they cause distribution of pigment granules.
II. Microfilaments (Actin Filaments):
They were discos
They occur in almost all eukaryotic plant and animal cells. They form sheets or bundles below the plasma membrane. They are abundant in muscle cells.
Microfilaments are long solid fibers of 7 nm in diameter. Each microfilament consists of two helically coiled protein chains called F-actin. Each F-actin is a polymer of G- actin or globular actin.
1. They are involved in cyclosis or cytoplasmic streaming by which coordinated movement of organelles, occur through cytosol.
2. They cause growth of the pollen tube down the style towards the embryo sac.
3. They guide the exocytosis and endocytosis of vesicle at appropriate sites. Such as site of cell wall formation.
4. They are responsible for cleavage at the time of cytokinesis of animal cells.
5. They are responsible for cellular movements such as contraction, crawling, gliding and movement of microvilli.
III. Intermediate Filaments (IFs):
They are most stable element of cytoskeleton. IFs are hollow filaments of 8-10 nm in diameter, intermediate in size between microtubule and microfilament, (that is why they are called intermediate filaments). Its wall consists of overlapping tetramers of proteins.
Its are of four types:
(a) Keratin Filaments: They form keratin of skin;
(b) Neuro-filaments: They form a lattice with bundles of microtubules in axons and dendrons of nerve cells;
(c) Glial Filaments: they are found in astrocytes;
(d) Heterogeneous Filaments: They occur in muscles as basket around nucleus and connected to centriole.
Intermediate filaments are believed to play mechanical role in positioning various cell organelles, provide site for the attachment of microfilaments, function as cytoskeleton, structural proteins of skin and hair, cell shape etc. |
This artist's animation flies through the Kepler-20 star system, where NASA's Kepler mission discovered the first Earth-size planets around a star beyond our own. The system is jam-packed with five planets, all circling within a distance roughly equivalent to Mercury's orbit in our solar system.
The two Earth-size planets, which are presumably rocky, are Kepler-20e and Kepler-20f, and the three larger gas planets are Kepler-20b, Kepler-20c and Kepler-20d. The arrangement of the planets from the closest to its star to the farthest is: b, e, c, f and d, with the ordering of the letters reflecting the time at which the planets were initially discovered.
The Kepler-20 system is unusual in that the sizes of the planets alternate, with the closest in being large, followed by a small planet, and then continuing on with the planets switching back and forth in size. Astronomers are intrigued by this configuration because it completely differs from that of our solar system, where there is a clear separation between the four small, rocky inner planets, and the four giant, gaseous outer planets.
NASA's Ames Research Center in Moffett Field, Calif., manages Kepler's ground system development, mission operations and science data analysis. JPL managed the Kepler mission's development.
For more information about the Kepler mission and to view the digital press kit, visit http://www.nasa.gov/kepler. |
Asperger's disorder is a developmental disorder associated with social and behavioral patterns. This disease was discovered in 1944 by an Austrian physician Dr.Hans Asperger. Asperger's disorder falls under pervasive developmental disorder category. The other types of disorders associated with these categories are autistic disorders. In many cases, Asperger's disorders are associated with characteristic features of eccentric behavior and minimized communication patterns with respect to social conditions.
Children affected by Asperger's syndrome often are found in isolation, as they exhibit insecurity among their peer groups. They often have a preoccupation with their areas of interest. These children have greater difficulty in socializing with others as they emphasize on their own interests without social involvement. The significant clinical symptoms of the Asperger's syndrome include:
The degree of facial expression in these children is much less and they appear astounded most of the times. The coordination and timing of the expressions are often irrelevant to circumstances or situations around them. The vocabulary pattern is well developed in children suffering with Asperger's syndrome; however these children lack the ability to communicate effectively. The clinical manifestations of Asperger's syndrome are associated with the intensity of the affected behavioral pattern pertaining to social relatedness, social skills and communication skills.
Epidemiological analysis of Asperger's disorder indicate that this disorder is more predominant than cases pertaining to autism. Asperger's syndrome is caused because of many underlying factors which are associated with the functionality of the brain, genetic influence and also a combination of genetic and environmental factors. Many children have impaired motor development in Asperger's disorder.
A classical indication of Asperger's syndrome among children is their idiosyncratic or obsessive behavior towards a certain object or group of objects. The conversations of these children are often based on repetitive adherence to these objects. The comprehension pattern is often misinterpretative to the context or situation. For example some people suffering this disorder may not be able to understand a joke easily. An interesting fact associated with Asperger's syndrome includes the career path of a person based on childhood obsession. Asperger's disorder is also associated with learning disability as it involves motor skills and communication skills.
Diagnosis of Asperger's syndrome is based on clinical symptoms. It is essential to diagnose the residual part of the disease in adults to avoid psychological complications. In many cases depression acts as a precursor for the onset of Asperger's syndrome. Asperger's syndrome in adults can be noticed in many scenarios such as mismanagement of time, poor interpretation skills and comprehension.
Pervasive Development Disorder
The term Pervasive Development Disorders (PDDs) is an umbrella term used to refer to a group of developmental disorders of the brain function. These cover the whole family of autistic spectrum including Asperger syndrome, Heeler's syndrome and Rett disorder. As PDD covers such a wide spectrum, it is exhibited differently from child to child. Children with these disorders are often confused in their thinking and they have problems understanding the world around them. Since these conditions are identified in children around 3 years of age, which is a critical period in the child's development, they are called development disorders. Even if the condition begins earlier than 3 years of age, parents often do not notice the problem until the child is a toddler who is not walking, talking or developing as well as other kids of the same age.
Diagnosis of Pervasive Development Disorder
Much of the diagnosis depends on the accurate developmental history and evaluation of the current functioning of the child. Complete medical history and physical exam is done for a complete evaluation by doctors. Although there are no laboratory diagnosis in PDD, various blood tests and X rays are done to determine if there is a physical disorder causing these symptoms. In the absence of any physical disorder, the child is referred to a specialist in childhood development disorders such as psychiatrist or psychologist, pediatric neurologist or other professionals trained to treat PDDs. Inputs from the parents of the affected child, his/her teachers, and other adults who are familiar to the child are sought. Parents require ongoing counseling and support and they must understand that they are not responsible for the child's condition.
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Diseases, Symptoms, Tests and Treatment arranged in alphabetical order:
Bibliography / Reference
Collection of Pages - Last revised Date: December 6, 2023 |
The Legendary King: How the Figure of King Arthur Shaped a National Identity and the Field of Archaeology in Britain
By Elizabeth Gaj Proctor
BA Honors Thesis, the University of Maine, 2017
Abstract: The legend of King Arthur has spread throughout Western Culture to such an extent that he is a world-wide symbol of courtly chivalry, justice, and rightful kingship. The question of Arthur’s existence has captured public fascination and ignited scholarly debate. To understand this fascination, we need to look at the development of Arthurian legend by examining the historical context in which the nation of Great Britain was created through the overpowering of indigenous cultures and a consolidation of medieval kingdoms by outside groups.
Drawing from archaeological evidence, historic, and current sources, we can understand King Arthur’s role as a symbol of Britain, which has affected the narrative of Tintagel Castle as the birthplace of King Arthur. Tintagel Castle is a major tourist destination and is currently undergoing excavations. These have been widely publicized, following a tradition of linking archaeological evidence and artifacts to Arthurian legend.
This research delves into the rhetoric used to justify support for Arthurian archaeology. The legend of King Arthur is not a static story, yet most people know only one version of it. The proto-nationalist forces that shaped the legend of King Arthur, combined with the commercialization that surrounds the archaeology of Arthurian sites, promote an idealized version of British history, which continues to affect current events and the national identity of British peoples. There needs to be a more nuanced, responsible approach Arthur to reflect archaeological evidence and real history. To conclude this thesis, I will suggest possible alternatives to the current presentation of Tintagel.
Top Image: Tintagel Castle – photo by Ben Salter / Flickr |
Heart failure is a condition in which the heart does not pump efficiently, consequently reducing the body’s supply of oxygen-rich blood. The lack of oxygen leads to a loss of energy and strength. Shortness of breath, swollen legs, coughing and fatigue are all typical symptoms. Heart failure is not, however, a normal part of aging. Timely and consistent treatment is essential to prevent, or at least delay, serious consequences.
First, if possible, it is crucial to treat the underlying disease and minimize existing risk factors. Certain medications can relieve the heart’s workload and have a beneficial effect on the course of the disease. Some people benefit from a pacemaker or cardiac surgery that increases the patient’s resilience. Acute heart failure, however, is always a medical emergency requiring immediate—usually in a specialized clinic. Acute heart failure is characterized by an overload of fluid in the body and lungs, which leads to shortness of breath, coughing and acute respiratory distress. Patients with symptomatic acute heart failure will receive water pills to get rid of excess fluid in the lungs and body.
- Medication can lower high blood pressure.
- Risks factors for coronary heart disease should be reduced (smoking, blood lipid level, diabetes mellitus, obesity). Generally speaking, a healthy lifestyle is a requirement rather than a recommendation for those with heart failure.
- "Biventricular stimulation" or "resynchronization therapy" (CRT) is indicated when the left heart chamber is enlarged and can therefore no longer beat synchronously. In this case, a pacemaker system is used to resynchronize the beating of both heart chambers, so that the heart can work efficiently again.
- In some cases, a special CRT device, a so-called implantable cardioverter-defibrillator (ICD) is implanted to stop potentially life-threatening cardiac arrhythmias by delivering energy to heart muscle. An ICD can also be used in resynchronization therapy.
Often patients with heart failure also suffer from comorbidities that worsen with age. Several cases can be distinguished:
- Comorbidities like high blood sugar level or coronary heart disease may be direct causes of heart failure.
- Diseases such as anemia (a deficiency of red cells or of hemoglobin in the blood), kidney failure, depression or sleep apnea are associated with heart failure and have a disease-promoting effect.
Currently a holistic approach, which takes any comorbidities into account, is used to treat heart failure,. Even slight anemia can have an adverse effect on the course of the disease. The same applies to kidney failure, depression or sleep apnea. Therefore, it is essential to treat both heart failure as well as any comorbidities affecting the patient’s general condition. When treating comorbidities with medication, possible interactions need to be taken into account. For instance, certain painkillers and some antidepressants are less suitable in patients with heart failure. Patients should always talk with their doctor about their current intake of medication. Pharmacists can also provide advice on potential interactions or side effects of medication.
If affected, consider the following:
- Do not smoke or consume alcohol.
- Eat well-balanced meals that are high in fiber (whole grains). The mediterranean diet is ideal as it includes a lot of vegetables and fruit, seafood, healthy oils (such as olive and canola oil) and little animal fat
- Exercise regularly
- If you suffer from heart failure, weigh yourself daily and record your body weight. If you notice a rapid weight gain, fluid retention could be the cause—a possible sign of acute heart failure. In this case talk to your doctor immediately. They may recommend a maximum fluid intake per day which you should not exceed. Eat a low-salt diet. Also, look for hidden salt, for example in ham, smoked meat, tomato ketchup, salted herring, and numerous other processed foods.
- If overweight, lose weight without resorting to strict diets or fasting. Discuss a suitable diet with your physician and/ or a qualified nutritionist., along with an individualized exercise plan.
- Learn to deal with stress or avoid it. Relaxation exercises such as autogenic training or yoga can help.
- Undergo regular check ups. Have any diseases such as high blood pressure, diabetes mellitus, or elevated cholesterol level treated. Also, take your medication regularly as directed by your physician. |
Physically, adolescents grow to reach their adult height, and their bodies begin to resemble adult bodies in size, shape, and body composition. Moreover, they become capable of sexual reproduction.
Cognitively, adolescent thinking skills rapidly advance as they enter Piaget's stage of formal operations. Youth are now able to think in abstract terms so that they can conceptualize theoretical ideas, moving beyond the limitations of concrete information. Youth begin analyze problems in a more logical and scientific manner. This ability to think abstractly and analytically simultaneously promotes their social, emotional, and moral development. As their brain continues to develop, youths' capacity for memorization expands as the brain develops more sophisticated methods of organizing information, allowing for more rapid and accurate information storage and subsequent retrieval. However, the brain's frontal lobe is not fully developed until the very end of adolescence. The frontal lobe of the brain enables humans to inhibit primitive sexual or emotional impulses by using rationale thought to override these impulses. The incomplete development of the frontal lobe means that adolescents will continue to struggle to make wise and thoughtful decisions in the presence of powerful emotional, social, or sexual pressures.
Emotionally, adolescents encounter many new experiences that challenge their ability to cope with a broad array of intense emotions. Youth must learn how to handle stressful situations that trigger powerful emotions without harming or hurting themselves, or other people. Once youth have learned to identify their emotions, and the source of their emotional reactions, they must then learn healthy ways to cope with situations that cause strong emotional reactions. When this learning is completed, youth will have developed emotional efficacy; a landmark skill that enables them to be successful in their future careers, and to enjoy meaningful relationships with others.
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Emotional maturity is closely tied to the knowledge of oneself, and one's values. This self-identity develops and solidifies during adolescence. Erik Erikson and James Marcia both proposed theories of identity development and these theories were reviewed. Despite theoretical differences, both theorists agree some youth will develop a clear set of values and beliefs through experimentation with different identities, and an examination of their values. Other youth will not advance this far. These youth will either continue to question their values; or, they may not examine their values at all. Some youth are so disadvantaged they do not have opportunities to explore values beyond mere survival.
Socially, as youths' need for independence increases, their primary social support shifts away from their families, and toward their peers. Because of the increased importance of peer relationships, youth are especially sensitive to peer pressure (meaning, to conform to the standards of the peer group). By late adolescence youth will ordinarily re-establish close relationships with their families, provided these relationships were positive to begin with. Youth also create more meaningful and productive relationships with other people outside their circle of family and friends; e.g., bosses, coaches, teachers, co-workers, and other acquaintances. Romantic relationships begin to flourish during this developmental phase. In early adolescence these connections may be of a more flirtatious nature, and may bloom and fade rather quickly. However, by late adolescence, many of these relationships become more stable, mature, and emotionally intimate.
Moral development naturally progresses as mental and emotional maturity improves. Youths' understanding of right and wrong becomes more sophisticated and nuanced. Both Piaget's and Kohlberg's theories of moral development were reviewed, but Kohlberg's theory has been more strongly supported by the research. According to Kohlberg's theory, some youth will eventually base their moral decisions on a set of ethical principles that surpass existing laws or rules. Other youth will remain primarily concerned with rules, laws, and fairness.
Sexual development was described as a complex merger of physical, cognitive, emotional, social, and moral development. During this time youth solidify their gender identity as masculine, feminine, or transgendered. Youth will also become aware of their sexual orientation which refers to a pattern of attraction to others, not sexual behavior. Youth will begin to realize they are primarily attracted to the opposite gender (straight), the same gender (gay or lesbian), both genders (bisexual), or still uncertain (questioning). During early adolescence most teens become curious about sex, but any sexual behavior is usually limited to masturbation. However, by middle to late adolescence, many teens begin to experiment with various sexual behaviors via masturbation, partners, or both. Because of the brain's incomplete development youth are at risk for making poor or risky decisions regarding their sexuality. Ultimately youth must determine what type of sexual behavior is acceptable to them, and under what circumstances. These decisions are best made in advance of the need to make them.
In conclusion, adolescent youth experience monumental changes in every single aspect of their lives as they make the transition from childhood into adulthood. The purpose of this article was to provide parents and other caregivers the foundational information needed to recognize and to appreciate the normal developmental progression of adolescents. Therefore, this article was primarily descriptive in nature. However, the process of adolescent development can become quite challenging and sometime overwhelming for both youth and their families. The next article in this series will build upon this foundation to provide parents and other caregivers concrete advice and practical solutions to common problems that arise during adolescence. Armed with this information, caregivers will feel more confident and successful as they guide their child through these often confusing and difficult years.
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Materials that can withstand extreme temperatures are used in jet engines, nuclear power plants and many civil engineering structures. The development process of these materials is expensive and time-consuming because it requires rigorous testing to measure material strength in an extreme environment.
Researchers can save processing time by testing a smaller size specimen. However, it is much harder to perform material testing on a small specimen since both the application of a thermal load on a small specimen and the measurement of deformation are experimentally challenging. The experimental techniques used to test a standard size specimen cannot be used for a small test specimen.
Tasnim Hassan, CCEE professor, and Farhan Rahman, CCEE postdoctoral researcher, collaborated with Department of Mechanical and Aerospace Engineering researchers Gracious Ngaile and Lin Li, to devise innovative experimental solutions that allow high-temperature material testing using small-size specimens.
The researchers developed a novel heating technique to apply uniform temperature distribution on a small specimen called hybrid heating, which uses Joule heating by passing electricity through a metal test specimen in conjunction with small custom-developed heating coils. When electricity passes through a metal test specimen, it heats up due to its internal resistance to the flow of current. Since this resistance is dependent on the cross-section of the test specimen — which changes during a test — a non-contact temperature control system using infrared thermography was devised. This novel hybrid heating system allows researchers to achieve uniform temperature on a small test specimen.
To measure the deformation of a small test specimen at high temperatures, researchers used the stereo digital image correlation (stereo-DIC) method — an optical technique that relies on multiple cameras to capture images of the test specimen as it deforms.
“What is unique about our stereo-DIC setup is that we developed an optimization framework that addresses the relationships among test specimen size and curvature, specimen to camera distance, stereo-angle, lens and camera sensor properties,” Rahman said. “This ensures high measurement accuracy from the stereo-DIC setup, which is important for accurate material property determination.”
The non-contact temperature control and deformation measurement systems allow researchers to measure material properties at high temperatures using small test specimens. The novel experimental techniques were devised as part of a new multiaxial miniature testing system (MMTS) researchers developed through a National Science Foundation research grant. The MMTS was designed to perform in-situ tests within a scanning electron microscope and thereby correlate material microstructures to their properties. |
“Remember” by Joy Harjo
The foundation of a 21st-century American community is shared respect among individuals who come from different backgrounds, places, and experiences. Native Americans take that concept even further by valuing all the inhabitants of the earth and sky—animal, vegetable, mineral, and spirit. As first inhabitants of our land, they set a model for inclusiveness in light of diversity. In her poem “Remember,” Poet Laureate Joy Harjo, a member of the Muscogee Creek Nation reminds us to pay attention to who we are and how we’re connected to the world around us.
This lesson plan provides a sequence of activities that you can use with your students before, during, and after reading “Remember.” Use the whole sequence, or any of the activities, to help your diverse learners enter, experience, and explore the meaning of the poem. Feel free to adjust each activity to meet the needs of your particular students. This lesson can be adapted for secondary students in grades 6–12.
This lesson is an adaptation of an original lesson by the Academy of American Poets Educator in Residence, Madeleine Fuchs Holzer.
How are we connected to places and people we do not know?
Students will listen to a Native American song for its sounds and rhythms in order to understand how it is structured.
Students will compare the structures and content of a spoken and written poem to those in a Native American song.
Students will explore poetry as a means of understanding the most important things to remember about their particular heritage.
Students will explore poetry as a means of understanding; the most important things to remember to keep our American community alive and functioning in the 21st century. |
How to Doodle a Turtle
If someone asked you to draw a turtle, what kind of turtle would you draw? Maybe, not so much “what kind”, but rather in what way? Let’s draw a turtle from one possible perspective. Begin by drawing the turtle’s shell. Use a couple of arc shapes to draw the upper and lower section of the turtle’s shell. Notice also how the turtle shell is on a bit of an angle.
Use a couple of elongated arc shapes to draw the turtle’s head. If you notice in the example, I have used two arc shapes of different depths to draw the head of the turtle. Notice also the head and neck positioning and how it is extending out of the shell area.
Use several additional arc shapes for the turtle’s legs and one more for the tail. Notice in the example how the legs closer to us (left legs) are drawn in full. While the legs further away from us are only partly visible. It is, therefore, easier to draw the left legs first, then to draw the right legs.
Let’s now give the turtle a little more detail. First, let’s decorate the turtle’s shell. Draw cloud shapes on the turtle’s shell as shown in the example. Your drawing doesn’t need to look like the example. Feel free to create your own pattern of cloud shapes on the shell. Then use an oval shape for the eye and a curved line for the mouth.
Add the finishing touches to your doodle by giving it some color. Notice how the legs further away from us are a slightly darker green color. This is a simple shadow effect. And there we have it. This is our visual representation of what a turtle looks like. To challenge yourself, you can, however, try drawing your turtle from another angle. Give it a go and see what you come up with. |
The lack of a deep covering of snow this season has been a benefit to some forms of wildlife, and a detriment to others. Yet for the beaver (Castor canadensis), the limited amount of snow on the ground has had little impact on this rodent’s winter routine.
Throughout the autumn, when the water around its primary lodge remains open, the beaver scours the shore near and far in search of those select woody plants on which it relies for food. These items are severed at their base and floated to the area just outside the main entrance to the family’s winter shelter and then pushed underwater as deep as possible.
Like many rodents, the beaver assembles a sizeable cache of food for use in winter when travel conditions become limited. Additionally, this rather rotund mammal develops deposits of fat that help to insulate it against the cold and can be used to fuel its internal energy needs.
As ice forms along the shore and around its lodge, the beaver starts to curtail its nightly foraging excursions and develops a more sedentary lifestyle. The stick and twig lodge that was packed with a coat of mud and sediment from the bottom of the pond during early to mid autumn now becomes the family’s full time home. Prior to mid-autumn, the beaver is known to rest during the day in a number of temporary shelters located throughout this creature’s territory. This allows its winter lodge to remain relatively free from the skin parasites that can eventually infest the sleeping quarters with nearly continuous occupancy.
By packing mud into the many cracks and crevices that exist between the stick and branch framework of this familiar, cone-shaped structure, the beaver helps seal out cold air and keeps in the warmth that the individuals in the family radiate to this small enclosure.
Yet, regardless of how much gushy material a beaver dredges up from the bottom of its aquatic domain, and deposits on the roof and walls of its lodge, there are always enough small holes and spaces just under sizeable limbs in the sides to allow some fresh air to enter the chamber and the carbon dioxide inside to escape. Even following a period of freezing rain, when a solid layer of ice forms on the roof, the naturally occurring holes on the sides that lead to the interior still provide for adequate ventilation of this shelter.
A substantial blanket of snow, such as the one the region experienced late last February and March, does create a thermal insulating layer over the lodge; yet several experiments have shown that the interior still remains very near 32 degrees. When snow is lacking and the outside air falls well below zero, the temperature inside may drop to a degree or two below freezing. As the sun shines on the southern walls of the dark, earthen lodge during an outbreak of arctic air, it effectively absorbs this solar energy, and the temperature inside returns to the freezing point and stays there until well after sunset.
As a general rule, the occupants periodically plunge into the icy water of the entrance and swim to their food cache to grab something to eat. During the early part of winter, many of the deeper limbs and twigs that were stored are easily accessed from the large pile assembled there. As the winter progresses and the layer of ice overhead expands downward into the pile of stored brush, the beaver must free most food items from the ice above. Because the beaver has the ability to gnaw while it is underwater, it only takes a few bites with its set of sharp incisors to sever those parts embedded in the ice and haul the remaining piece back into the lodge.
Because water is far more dense than air, heat is lost from this mammal at a much faster rate when it is immersed in water than when it is sitting on a dry shelf inside its lodge. This more rapid cooling prevents the beaver from entering the water more than it has to in order to expel its wastes and grab a quick meal.
During periods of unseasonably cold weather, the occupants of a lodge may remain inside in a very quiet state, huddled together in order to limit the cooling effect that occurs when an individual plunges into the water and reenters the lodge having lost some of its body heat.
The winter routine of a beaver is far different from that which this animal experienced just a few months earlier as it was preparing for this season of cold and ice. The reputation of the beaver as an energetic and highly productive creature comes from its autumn activities. For the present time, this rodent leads a life that is more reminiscent of a sloth.
Illustration courtesy Wikipedia. |
HTML is the main markup language for describing the structure of web pages.
HTML stands for HyperText Markup Language. HTML is the basic building block of World Wide Web.
Hypertext is text displayed on a computer or other electronic device with references to other text that the user can immediately access, usually by a mouse click or key press.
Apart from text, hypertext may contain tables, lists, forms, images, and other presentational elements. It is an easy-to-use and flexible format to share information over the Internet.
Markup languages use sets of markup tags to characterize text elements within a document, which gives instructions to the web browsers on how the document should appear.
HTML was originally developed by Tim Berners-Lee in 1990. He is also known as the father of the web. In 1996, the World Wide Web Consortium (W3C) became the authority to maintain the HTML specifications. HTML also became an international standard (ISO) in 2000. HTML5 is the latest version of HTML. HTML5 provides a faster and more robust approach to web development.
Tip: Our HTML tutorial will help you to learn the fundamentals of the latest HTML5 language, from the basic to advanced topics step-by-step. If you're a beginner, start with the basic section and gradually move forward by learning a little bit every day.
What You Can Do with HTML
There are lot more things you can do with HTML.
- You can publish documents online with text, images, lists, tables, etc.
- You can access web resources such as images, videos or other HTML document via hyperlinks.
- You can create forms to collect user inputs like name, e-mail address, comments, etc.
- You can include images, videos, sound clips, flash movies, applications and other HTML documents directly inside an HTML document.
- You can create offline version of your website that work without internet.
- You can store data in the user's web browser and access later on.
- You can find the current location of your website's visitor.
The list does not end here, there are many other interesting things that you can do with HTML. You will learn about all of them in detail in upcoming chapters.
Note: HTML as described earlier is a markup language not a programming language, like Java, Ruby, PHP, etc. You need a web browser to view the HTML pages. The web browsers do not display the HTML tags, but uses the tags to interpret the content of the web pages.
What This Tutorial Covers
This HTML tutorial series covers all the fundamentals of HTML, including the idea of elements and attributes, way of formatting the text using HTML tags, methods of adding the style information to the document, technique of inserting images and tables, process of creating lists and forms as well as method of including other HTML documents inside the current document, and so on.
Once you're familiar with the basics, you'll move on to next level that explains the concept of doctype, methods for creating the web page layouts, importance of adding meta information to the web pages, way of adding scripts, techniques of showing special characters, anatomy of a URL, and more.
Finally, you'll explore some advanced features introduced in HTML5 such as new input types, drawing graphics on the webpage, including audios and videos in the document, storing data on client-side using web storage, caching files, performing background work with web worker, as well as getting user's geographical coordinates, creating drag and drop application, and so on.
Tip: Every chapter in this tutorial contains lots of real-world examples that you can try and test using an online editor. These examples will help you to better understand the concept or topic. It also contains smart workarounds as well as useful tips and important notes. |
One aspect of dyslexia that receives little attention is that the challenges of dyslexia predispose children to anxiety and behavioral changes. Sometimes anxiety and behavioral problems may surface in a young child after starting school but before any of the various symptoms of dyslexia are noticed. In cases of undiagnosed dyslexia, anxiety and other attendant behavioral problems can often overshadow the underlying cause.
To be clear, not all dyslexics are alike. There are varying degrees and areas of involvement. In addition, dyslexia has many sibling conditions like dyscalculia, dysgraphia, dyspraxia, and dyspraxia of speech (see list below). Of course, not all children with anxiety or behavioral issues have dyslexia, but many do, so there are certain symptoms that should be noted and investigated. For dyslexia awareness month I wanted to share one of my recent articles, Is Dyslexia the Root of Your Child’s Anxiety and Behavioral Problems, published August 16, 2017, in MD Monthly.
Check out the article, and if you observe any of the traits or tendencies described in the article in your child or student, don’t wait—talk to your child’s physician about next steps to get your child the help he or she needs.
Lesser-known sibling conditions of dyslexia:
- Dyscalculia: trouble with math, numbers, sequencing, sense of direction, and time management
- Dysgraphia: illegible handwriting or printing, incompletely written words or letters, poor planning of space [running out of room], strange contortions of body or hand position while writing, struggle or inability to take notes, which requires thinking, listening, and writing simultaneously
- Dysphonia: difficulty differentiating and interpreting the different sounds of spoken words
- Dyspraxia of speech: misspeaking words, and/or halting speech. This aspect of dyslexia is because the brain has problems planning to move the body parts [e.g., lips, jaw, tongue] needed for speech. The child knows what he or she wants to say, but his/her brain has difficulty coordinating the muscle movements necessary to say those words)
- Dyspraxia: an issue that involves the whole brain, affecting functions such as gross [large] muscle movements and coordination, fine motor skills [pen grip, unclear hand dominance, trouble fastening clothes and tying shoes, difficulty writing on the line on paper], clumsy, accident-prone behavior due to proprioceptive challenges [telling where the body is in space], trouble telling right from left, and erratic, impulsive, or distracted behavior
To access my previous dyslexia-related blogs and articles, check out my Dyslexia Articles page. |
Rectifiers convert alternating current to direct current, whereas inverters convert direct current to alternating current. Because both the rectifier and the inverter change one quantity to another, they are classified as converters. The difference is that the inverter uses transistors to switch power supplies on and off, thus creating the oscillation effect.
The transistor used in the inverter can be either an N-type or a P-type transistor. An N-type transistor will conduct when its base is connected to positive voltage, while a P-type transistor will conduct when its base is connected to negative voltage. Both types of transistors are available in market, so it doesn't make any difference for an inverter to use one type of transistor rather than the other. However, if you need a very small inverter to drive some small electronics, then using p-channel transistors may not be such a good idea because their behavior is more sensitive to voltage than N-type transistors.
In conclusion, no, the rectifier and the inverter are two separate components. They can be from the same manufacturer and still be separate components. For example, a Siemens 1KW inverter module will have its own rectifier module also made by Siemens. The two components are separate because even though they are from the same manufacturer, they operate completely independently of each other.
Electrical devices that transform current are known as converters and inverters. Converters convert an electric device's voltage, commonly alternating current (AC), to direct current (DC). Inverters, on the other hand, convert direct current (DC) to alternating current (AC). For example, a power supply converts AC electricity from your wall socket to DC for your electronics. A motor drives a generator which produces three-phase AC, which can be used by another motor to work hard or pump water.
In addition to power supplies and motors, some electrical devices require conversion between AC and DC processes to operate correctly. For example, many lamps require a DC source to function properly; they cannot use an AC signal because they are designed to work with a constant voltage rather than with an alternating current signal like that produced by a motor or generator. Other examples include heaters and air conditioners, which need regular doses of DC current to function properly, or electronic clocks, which must have their own battery source since they do not run on AC power.
Conversion of signals between different electrical systems is also important for interconnecting computers within a network or connecting appliances in a home wiring system. Each computer has a defined role to play on the network: Some act as servers where large amounts of data are stored or complex tasks performed, others as clients who request information or services, and still others as routers who communicate messages between other computers.
Rectifiers convert alternating current to direct current, whereas converters convert direct current to alternating current or direct current to direct current. Simply described, a rectifier is an AC to DC converter that exclusively uses diodes. With the aid of thyristors, the converter is also an AC to DC converter. The term "rectifier" comes from the fact that it requires only four wires (or terminals) to connect its input circuit to the load: ground, line voltage, neutral, and load voltage.
In practice, most power supplies use a combination of rectification techniques. In particular, six-diode bridges are still used for low-power applications where size is important. For higher powers, two six-diode bridges are often connected in parallel to increase the current capacity. This is called a "flyback" bridge because it functions like a transformer with two loops - one for input voltage, the other for output voltage. Each diode in the bridge forms a side loop that operates when the other diode is conducting. This allows both inputs to be connected to line voltage at the same time, providing extra safety against electrical faults.
The purpose of the power supply is to deliver a stable voltage level to a load, such as an electronic device. A power supply can be divided into three main parts: input filter, regulator, and output filter. The input filter consists of capacitors which remove high frequency components from the line voltage signal.
An alternating current to direct current converter Power electronics converters are classified into several sorts, including rectifiers, inverters, voltage regulators, F to V converters, cycloconverters, and so on. A rectifier circuit is a power electronics converter that is used to convert AC to DC. The most common type of rectifier is the full-wave rectifier, which converts the AC signal into a high-voltage DC signal that can be used directly by a load such as an LED lamp or an electric motor.
A capacitor can be added in parallel with a resistor to increase the value of R or reduce the amount of current flowing through it. This is called "loading" the resistor. Loading increases the resistance value of the resistor. And hence, less current will flow through it. Therefore, more heat will be generated due to the same amount of power being drawn from the source.
The addition of a capacitor in parallel with a resistor is very useful when trying to save energy. For example, if you have an LED lamp and you want it to stay on even when you turn off the main power supply, then you can add a small capacitor (with a capacitance of about 10 uF or more) in parallel with the LED lamp. Now even when you turn off the main power supply, the voltage will still be present on the capacitor and the LED lamp will remain on.
Inverters are electrical devices that provide alternating current. They change direct current (DC) to alternating current (AC). Inverters and rectifiers are employed in every sector, including power engineering, telecommunications, and trains...
The main difference between an inverter and a rectifier is that the output of a rectifier is direct current while that of an inverter is alternating current. An inverter can also be called a AC generator because it produces electricity from mechanical movement (rotation) by using semiconductor components rather than electromagnets or carbon brushes. Thus, it functions as a motor-alternator combination.
An inverter can also convert DC voltage into AC voltage. This function is useful when supplying power to equipment that requires AC voltage but can handle DC voltage. For example, if your state law prohibits you from running your sump pump during an electric outage, an inverter can keep the pump running during times when the power company says there is no electricity available.
Finally, an inverter can convert AC voltage into DC voltage. This function is useful when supplying power to equipment that operates on DC voltage (such as battery chargers) or when recovering energy from AC systems (such as air conditioners) for reuse or storage. |
What is Staphylococcus aureus (staph)?
Staphylococcus aureus, often referred to simply as "staph," are bacteria commonly carried on the skin or in the nose of healthy people. Approximately 25% to 30% of the population is colonized (when bacteria are present, but not causing an infection) in the nose with staph bacteria. Sometimes, staph can cause an infection. Staph bacteria are one of the most common causes of skin infections in the United States. Most of these skin infections are minor (such as pimples and boils) and can be treated without antibiotics (also known as antimicrobials or antibacterials). However, staph bacteria also can cause serious infections (such as surgical wound infections, bloodstream infections, and pneumonia)
What is MRSA (methicillin-resistant Staphylococcus aureus)?
Some staph bacteria are resistant to antibiotics. MRSA is a type of staph that is resistant to antibiotics called beta-lactams.
Beta-lactam antibiotics include methicillin and other more common antibiotics such as oxacillin, penicillin and amoxicillin. While 25% to 30% of the population is colonized with staph, approximately 1% is colonized with MRSA.
Who gets staph or MRSA infections?
Staph infections, including MRSA, occur most frequently among persons in hospitals and healthcare facilities (such as nursing homes and dialysis centers) who have weakened immune systems. These healthcare-associated staph infections include surgical wound infections, urinary tract infections, bloodstream infections, and pneumonia.
What is community-associated MRSA (CA-MRSA)?
Staph and MRSA can also cause illness in persons outside of hospitals and healthcare facilities (see healthcare-associated MRSA). MRSA infections that are acquired by persons who have not been recently (within the past year) hospitalized or had a medical procedure (such as dialysis, surgery, catheters) are know as CA-MRSA infections. Staph or MRSA infections in the community are usually manifested as skin infections, such as pimples and boils, and occur in otherwise healthy people.
How common are staph and MRSA infections?
Staph bacteria are one of the most common causes of skin infection in the United States and are a common cause of pneumonia, surgical wound infections, and bloodstream infections. The majority of MRSA infections occur among patients in hospitals or other healthcare settings; however, it is becoming more common in the community setting.
Data from a prospective study in 2003, suggests that 12% of clinical MRSA infections are community-associated, but this varies by geographic region and population.
What does a staph or MRSA infection look like?
Staph bacteria, including MRSA, can cause skin infections that may look like a pimple or boil and can be red, swollen, painful, or have pus or other drainage. More serious infections may cause pneumonia, bloodstream infections, or surgical wound infections.
How can I prevent staph or MRSA skin infections?
Teach your employees proper health and hygiene:
Employees must wash hands thoroughly with soap and water or use an alcohol-based hand sanitizer.
Keep cuts and scrapes clean and covered with a bandage until healed.
Avoid contact with other people’s wounds or bandages.
Avoid sharing personal items such as towels or razors.
Are staph and MRSA infections treatable?
Yes. Most staph and MRSA infections are treatable with antibiotics. If you are given an antibiotic, take all of the doses, even if the infection is getting better, unless your doctor tells you to stop taking it. Do not share antibiotics with other people or save unfinished antibiotics to use at another time.
However, many staph skin infections may be treated by draining the abscess or boil and may not require antibiotics. Drainage of skin boils or abscesses should only be done by a healthcare provider.
If after visiting your healthcare provider the infection is not getting better after a few days, contact them again. If other people you know or live with get the same infection tell them to go to their healthcare provider.
Is it possible that my staph or MRSA skin infection will come back after it is cured?
Yes. It is possible to have a staph or MRSA skin infection come back (recur) after it is cured. To prevent this from happening, follow your healthcare provider’s directions while you have the infection, and follow the prevention steps after the infection is gone. |
Definition of a Career
Concepts about career varied as researchers varied across the research community. Career is described as an occupation or a profession that involves special training or formal education and it is considered to be a person’s lifework. Career plays a fundamental and significant role in the life of an individual not only because they affect the individual’s personality and self-concept but because it is a chosen pursuit, lifework or success in one’s profession. This concept about career implies that a career is a lifelong endeavor. Thus, the choice of career and success in it are determined by the attitude, value, needs, previous experience and expectation of the person in question. For example, teaching can be taken as a career. Within teaching, one could be a principal (a position) bursar etc. all these are positions occupied within the teaching profession or career and to succeed in it, such a teacher have a good attitude towards the teaching profession, value it, need it, and have all the necessary requirements to succeed in it.
Defining a Career
After understanding the concept of a career, it now imperative to key the above concepts into definition. Accordingly, the Oxford English Dictionary (2013) defined career as a person’s course or progress through life or a distinct portion of life. In this definition, career is understood as relating to a range of aspects of an individual’s life, learning and work. Mckay (2014) defined career as an individual’s vocation or trade or how he or she makes a living. Career is often used interchangeably with the word occupation. Examples of careers are engineering, accountancy, or veterinarian etc. which one can choose to make a living. Career, according to Okpara (2009) is a sequence of occupation, jobs engaged in or occupied throughout the lifetime of the person. Psychologically, a career is a series of roles played by a person and it is person controlled. The Wikipedia (2013) clearly defined career as a course or progress through life (or a distinct portion of life). A third way in which the term career is used to describe an occupation or a profession is that it usually involves special training or formal education and is considered to be a person’s lifework. In this case a career is seen as a sequence of related jobs usually pursued within a single industry or sector e.g. “a career in law” or “a career in the building trade”. The term career can therefore be defined as the sequence of interaction of individuals with society, education and organizations throughout their lifespan. It is necessary however, to emphasize that the much of the responsibility now rests on the individual for their own career progression which requires sustained employability (Beukes, 2009; Herr, Cramer, & Niles, 2004).
Definition of Career by Admissions and UTME Nigeria
Consequent upon the above review of the definitions of a career, the author concludes that a career is the totality of expected, current and past occupation and/or jobs to be engaged throughout ones working age. This definition was adopted because it takes into cognizance the fact that even a secondary school student is anticipating a career. Therefore, a proper definition of a career should not only define someone already in a career but also someone anticipating a career.
Download the Full Material Here: Career Day
Cite downloaded material as follows:
Michael, O. J. (2018). Trends in career tutelage in contemporary societies: The need for an annual career day programme. Wilberforce Island: Admissions and UTME Nigeria.
Cite website content as follows:
Admissions and UTME Nigeria, (2018). Definition of a career. Retrieved from http://admissionsandutme.com/definition-of-career/ |
Editor's note: This blog post was originally published March 18, 2014.
Subtraction can be a very tricky concept for young children to understand. Addition seems to come naturally to children, but subtraction is more abstract and confusing. It's very important for young learners to see the connection between addition and subtraction to have a real understanding of the concept. The video below details several strategies for parents to explore with their children when learning subtraction. These concepts are based more on number sense and place value than the traditional algorithm. Exploring di?erent strategies can really help students as young as those in ?rst grade to understand the subtraction process and not just memorize the steps. |
Why do we need visualisation?
Firstly, it helps us identify areas that require attention easily, and secondly, any nice looking data usually serve to assist in understand and convince the readers.
Only some examples will be covered here, feel free to explore the functionality of ggplot here in this neat cheatsheet: https://www.rstudio.com/wp-content/uploads/2015/03/ggplot2-cheatsheet.pdf
Charts that we are going to cover in this tutorial:
- Single Variable Bar Chart
- Single Variable Density Plot
- Categorical Variables Bar Charts
- Box Plots
In this tutorial, we utilise the package ggplot2 and use the same dataset diamonds.
1. Single Variable Bar Chart
You will tell R to look for data from the dataframe “diamonds” using ggplot(), before adding other details to the plotting such as the type of plot using the geom_bar() (or other types of plots, which you will see below). After which, depending on the different type of plots, the aes() function usually will be used to define which are the variables to be used for the plotting.
ggplot(diamonds) + geom_bar(aes(x=cut,fill=cut))
2. Single Variable Density Plot
So here, beside the type of plot, we can include the title “Distribution of Price” into the visualisation.
ggplot(diamonds) + geom_density(aes(x=price))+ggtitle("Distribution of Prices")
3. Categorical Variables Bar Charts
In this plot, we add another function call facet_wrap(~cut), which ask R to divide the data set to plot the clarity of different cuts, so you don’t have to plot multiple times.
ggplot(diamonds) + geom_bar(aes(x=clarity, fill=clarity))+facet_wrap(~cut)
4. Box Plot
Combining pipe operator from dplyr, note that as we don’t have to specify that the data is from diamonds as it take the data after the filter.
diamonds %>% filter(cut=="Ideal")%>% ggplot(aes(x=color,y=price))+ geom_boxplot() |
Masks, physical distancing, good hygiene, and ventilation can help reduce the transmission of COVID-19 in public places. But even when these measures are taken, scientists have sometimes detected SARS-CoV-2, the virus that causes COVID-19, in indoor settings.
Now, Yale School of Public Health (YSPH) researchers have developed a passive air sampler clip that can help assess whether a person has been exposed to SARS-CoV-2, which could be especially helpful for workers in high-risk settings, such as health care facilities and restaurants. The device is described in the American Chemical Society journal Environmental Science & Technology Letters
“The Fresh Air Clip is a wearable device that can be used to assess exposure to SARS-CoV-2 in the air,” said the clip’s creator Krystal Godri Pollitt, an assistant professor of epidemiology (Environmental Health Sciences) at YSPH and an assistant professor of chemical and environmental engineering at Yale.
“With this clip we can detect low levels of virus that are well below the estimated SARS-CoV-2 infectious dose,” Godri Pollitt said. “The Fresh Air clip serves to identify exposure events early, alerting people to get tested or quarantine. The clip is intended to help prevent viral spread, which can occur when people do not have this kind of early detection of exposure.”
COVID-19 is primarily transmitted through the inhalation of virus-laden aerosols and respiratory droplets that infected individuals expel by coughing, sneezing, speaking or breathing. Researchers have used active air sampling devices to detect airborne SARS-CoV-2 in indoor settings; however, these monitors are typically large, expensive, non-portable, and require electricity. To better understand personal exposures to the virus, Godri Pollitt and her colleagues sought to develop a small, lightweight, inexpensive, and wearable device that doesn’t require a power source. The Fresh Air Clip was the result.
The device captures virus-laden aerosols that deposit on a polydimethylsiloxane (PDMS) surface. The team tested the air sampler in a rotating drum in which they generated aerosols containing a surrogate virus, a bacteriophage with similar properties to SARS-CoV-2. They detected virus on the PDMS sampler using the polymerase chain reaction (PCR) protocol, showing that the device could be used to reliably estimate airborne virus concentrations.
In further testing, the researchers distributed Fresh Air Clips to 62 volunteers, who wore the monitors for five days. PCR analysis of the clips detected SARS-CoV-2 RNA in five of the clips: Four were worn by restaurant servers and one by a homeless shelter staff person. The highest viral loads (more than 100 RNA copies per clip) were detected in two badges from restaurant servers. These results indicate that the Fresh Air Clip could serve as a semiquantitative screening tool for assessing personal exposure to SARS-CoV-2, and also help identify high-risk areas for indoor exposure, the researchers report in their study.
“The Fresh Air Clips are easy-to-use, non-invasive, and low-cost,” Godri Pollitt said. “These features make it easier to scale-up this kind of exposure monitoring for COVID-19 and other respiratory viruses so that the clips can be made available across larger groups of workers in high-risk jobs, such as restaurant servers, health care workers, and teachers.”
The Fresh Air Clip is currently being used in other research projects. Godri Pollitt said she hopes to make the clips available to the public in the future.
This research was supported by the National Science Foundation (NSF) and the Rothberg Fund. Dr. Jodi Sherman, associate professor of anesthesiology and of epidemiology (Environmental Health Sciences) at Yale and Jordan Peccia, Yale’s Thomas E. Golden Jr. Professor of Chemical & Environmental Engineering, were co-investigators on the NSF grant supporting this research. Yale doctoral student Darryl Angel and postdoctoral associate Dong Gao were co-first authors on the paper. |
A group of scientists has used starlight to test a feature of quantum mechanics that gave Albert Einstein the creeps.
Entanglement is what Einstein referred to as "spooky action at a distance." It's a phenomenon by which one particle can effectively "know" something about another particle instantaneously, even if those two particles are separated by a great distance. It appears to go against the idea that nothing, not even information, can travel faster than the speed of light.
Scientists who study this phenomenon want to be sure that nothing in their experimental setup is somehow creating the illusion of entanglement, perhaps via some physical mechanism or phenomenon that scientists don't yet know about. In an effort to close a possible loophole in entanglement experiments, a group of researchers used starlight as part of their experiment. The researchers say the results of their work provide further support for this "spooky" phenomenon. [Quantum Entanglement: Love on a Subatomic Scale]
Universal speed limit
If humans were to discover an intelligent species living on a planet 10 light-years away, it would take 10 years to send them a message that said "hello," and 10 more years for their reply to come back to Earth. If we discovered a civilization on an even more distant planet, it could take many human lifetimes just to start a conversation.
That's the law, according to Einstein: nothing can travel faster than the speed of light, so communications conducted over vast cosmic distances come with an inherent delay.
And yet, there is a feature of quantum mechanics that seems to violate that principle. Quantum mechanics is an area of physics that deals with subatomic particles. In this seriously small realm, things behave in a way that can seem totally contradictory to what we experience in the macroscopic world. One quantum phenomenon called entanglement postulates that pairs of entangled particles can effectively exchange information instantaneously. In theory, these particles could communicate instantly over vast cosmic distances.
This idea rattled Einstein; he never fully accepted it. And even today, scientists are working to make sure this strange phenomenon is real.
One of the more famous fables in quantum mechanics is about poor Schrödinger's cat, who got stuck in an uncertain state: the feline was neither alive nor dead until someone opened the box to find out. Uncertainty is another one of the truly freaky features of quantum mechanics. In the real world, something can either be alive or dead; in the quantum world, there's a third option in which the object's state hasn't yet been determined. To break the uncertainty, someone has to measure it (open the box) and force the object (cat) into one state (alive/dead).
Entangled particles also exist, initially, in an uncertain state. Particles can't be alive or dead, so instead think heads and tails. If you flip a coin 100 times, odds are it will come up heads close to 50 times and tails close to 50 times. If I then flip my own coin 100 times, there's a high probability the split will also be close to 50/50. But if our coins are entangled, then the outcome of your flip determines the outcome of my flip — perhaps our entanglement is such that every time you flip heads I flip tails. If we flip our coins enough times, our entanglement will begin to become obvious, because my outcome of my flip is no longer random, but determined by your flip, and the odds of my flipping tails every time you flip heads get lower and lower the more we flip.
That's sort of how scientists can measure entanglement. Instead of flipping a pair of coins over and over again, researchers measure the properties in many, many of pairs of entangled particles (entanglement can only be measured in a pair of particles once). But the scientists have to be sure that what they're seeing isn't just random chance.
A statement from the Massachusetts Institute of Technology (MIT) poses the question, "What if there were some other factors or hidden variables correlated with the experimental setup, making the results appear to be quantumly entangled, when in fact they were the result of some nonquantum mechanism?"
In other words, how can scientists be sure there's not some unseen factor affecting their experiments, and making it seem as though the examined particles are entangled, when in fact they are not?
A physicist named John Bell showed that if entanglement exists, then there must be a minimum degree of correlation between entangled particles when scientists measure them; this is known as Bell's inequality or Bell's theorem.
In some entanglement experiments, the detector measures a property of light particles called polarity; the detector must be oriented in one of two directions, and only photons polarized in the same direction (one of two possibilities) can pass through. In order to make sure that the detector is not somehow influenced by one of those mysterious forces that could corrupt the experiment, researchers will use random-number generators to determine the direction of the detector.
That random choice is made "in the split second between when the photon leaves the source and arrives at the detector," according to the MIT statement. "But there is a chance, however slight, that hidden variables, or nonquantum influences, may affect a random number generator before it relays its split-second decision to the photon detector,” the statement said.
This particular "loophole" in an experiment testing Bell's inequality is known as the "freedom-of-choice loophole." In 2014, a couple of scientists got together and came up with a new idea for how to avoid those possible influences, using starlight as the thing that randomly determines the direction of the detector. Now, those researchers have put their idea to the test. [How Quantum Entanglement Works (Infographic)]
"At the heart of quantum entanglement is the high degree of correlations in the outcomes of measurements on these pairs [of particles]," David Kaiser, professor of physics at MIT and co-author on the study, said in the statement. "But what if a skeptic or critic insisted these correlations weren't due to these particles acting in a fully quantum mechanical way? We want to address whether there is any other way that those correlations could have snuck in without our having noticed."
Every photon of starlight that reaches a telescope has a particular wavelength. In the new study, which was conducted in Vienna, Austria, the researchers set up a couple of telescopes and started collecting photons (the telescopes and detectors were placed on rooftops at the university, as well as the roof of the Austrian National Bank). They selected a reference wavelength, and each photon that hit the telescope would either have a longer or shorter wavelength than that reference point. A photon with a longer wavelength switched the detector to one orientation, and a shorter wavelength switched it to the other orientation.
"With bright stars like these, the number of photons coming in can be like a firehose," Andrew Friedman, an MIT research associate and co-author on the new study, said in the statement. "So we have these very fast detectors that can register detections of cosmic photons on subnanosecond timescales."
The researchers measured about 100,000 pairs of entangled photons with this method, and their results suggested that the particles were truly entangled.
The most distant stars used in the experiment are about 600 light-years away, which means the photons were emitted 600 years ago. If those photons were somehow tied to the state of the entangled photons, that connection would have to have been established 600 years ago, according to the statement.
"This experiment pushes back the latest time at which the conspiracy could have started," Alan Guth, a professor of physics at MIT and another co-author on the new study, said in the statement. "We're saying, in order for some crazy mechanism to simulate quantum mechanics in our experiment, that mechanism had to have been in place 600 years ago to plan for our doing the experiment here today, and to have sent photons of just the right messages to end up reproducing the results of quantum mechanics. So it's very far-fetched."
The study doesn't fully eliminate the possibility of some mysterious force acting on the experiment, but it certainly puts tighter restrictions on how and when such a thing could happen.
"The real estate left over for the skeptics of quantum mechanics has shrunk considerably," Kaiser said. "We haven't gotten rid of it, but we've shrunk it down by 16 orders of magnitude." |
Sponsoring Organization: HHS – Child Welfare
April is National Child Abuse Prevention Month, and we’d encourage everyone to get involved. Children will always be our most valuable resource. By making sure that parents have everything they need—information, skills, and resources—to take good care of their children, we can all contribute to a brighter future by preventing child abuse.
The theme for this year’s National Child Abuse Prevention Month is “Strong and Thriving Families,” and the goal is for individuals and organizations in every community to help build stronger, healthier and happier families. The first step is information: Do you know how to define child abuse? It can be tricky because people often assume child abuse just means physical abuse. The most common type of child abuse, however, is neglect. Putting a child in an unsupervised, dangerous situation is abusive. Exposing children to sexual situations or saying things that make them feel stupid or worthless are also forms of child abuse. Whether it’s physical, sexual or emotional, it’s important to know the warning signs.
Here are some common signs that a child may be going through abuse: A child is very withdrawn, afraid, or always anxious about doing something wrong; is constantly “on alert,” as if waiting for something bad to happen; flinches at sudden movements, or seems afraid to go home; clothes are consistently ill-fitting, dirty, or inappropriate for the weather; is frequently unsupervised or allowed to play in unsafe situations; makes an effort to avoid a specific person, without an obvious reason.
Everyone can play a part by being on the lookout for these warning signs. If you suspect that a child is being mistreated, here’s what you can do, according to the Child Welfare Information Gateway:
- If you believe the child is in immediate or serious danger, call 911.
- Call or text 1.800.4.A.CHILD (1.800.422.4453). Professional crisis counselors are available 24 hours a day, 7 days a week, in over 170 languages. All calls are confidential. The hotline offers crisis intervention, information, and referrals to thousands of emergency, social service, and support resources.
- If a child is being exploited online (or has been contacted inappropriately online), make a report with CyberTipline.
Sometimes families need support, and by reporting signs of abuse, you can help by connecting struggling parents with resources. Information you report to child abuse hotlines will be made available to Child Protective Services (CPS). A CPS worker can then help the parents or other caregivers get services, education, or other assistance for the child.
Additionally, it is important to note, the risks of child abuse are exacerbated as a side effect of the COVID-19 Pandemic. Families are facing all new stresses as businesses and schools begin to shut down, people are increasingly facing economic instability, and families are forced to self-isolate. All three of these could potentially increase the risk of domestic and child abuse.
Right now it is more important than ever to report signs of abuse if you see or suspect it. Visit the End Violence Against Children website for information on reducing risk, reporting abuse, and more during this COVID-19 pandemic.
The good news is that effective child abuse prevention works. The partnerships created between child welfare professionals, community organizations and families have been proven to succeed. Get involved and help raise awareness about National Child Abuse Prevention Month in your community. Be the reason our families are strong, and our children have a future they deserve. |
More than 150 years after the Civil War, Americans don’t understand what caused this pivotal conflict. You can hear the ignorance in the debates we have about the Confederate flag and statues of Confederate generals.
In 2015, the Pew Research Center conducted a poll to explore Americans’ beliefs about the war. The results indicated that 48% of Americans believe the southern states seceded because of states’ rights and 38% of people believe the South seceded over slavery. So who’s right?
History isn’t simple, but we like simple answers.
So to put it simply, slavery caused the Civil War. People who argue that the southern states seceded because of states’ rights are only correct in that the right these states wanted to control was the right to own slaves without restriction by the federal government. You can read the evidence in the Confederate states own words, namely the Ordinances of Succession.
This is old history, but it matters. Racial tensions plague our nation, and these problems are rooted in America’s past as a slave nation. Peace and justice will not come until we fully understand our history.
So history teachers, the burden is on your shoulders.
Help your students dig into the historical data so they can reach conclusions based on evidence rather than myth. Here is a lesson I used with my high school students.
- Put students in groups of three and have them read the Ordinances of Succession of the 13 Confederate States of America. It’s best to assign each group one state.
- As they read, have students list the reasons the state gave for leaving the Union. Categorize these reasons. Possible categories include slavery, states’ rights, economic issues, or concerns about the leadership of President Lincoln.
- Ask students to visually portray how much they think each category influenced that state to secede. Possible visuals include a pie graph or word cloud or sketch. The visual should balance each category in terms of its importance as indicated in the Ordinance of Succession.
- The students should share their visual with the whole group, explaining the reasons given for secession by the state whose ordinance they read.
- After listening to all groups, students should write a thesis that states why the Confederate states seceded from the United States.
- To extend the lesson, students could conduct their own informal poll at school to determine what teachers and students think caused the Civil War. Do the poll results conflict with what the students discovered through reading the Ordinances of Succession? If so, how do students explain this discrepancy? |
A satirical work that critiqued the lives and behaviors of British colonialists in India. Atkinson served with the Bengal Engineers between 1840 and 1859. Written immediately following the Sepoy Rebellion of 1857, the work describes a fictional Indian village called Kabob. Included in the narrative are forty full-page tinted lithographs of daily life around the village, which he illustrated himself. Atkinson caricatured colonial officials in a humorous way, presenting brief vignettes of different fictional British characters residing in the village. He was inspired by Sir Charles Doyley’s depictions of Britishers in India, but he took a more critical approach to interpreting the relationships between the British and their colonial subjects. Native Indians were seen as treacherous and unchangeable following the Sepoy Rebellion; British colonialists distanced themselves from their subjects and exaggerated their social values in an effort to preserve their “Britishness” within the foreign space of India. The work enjoyed a long period of popularity among the British following Atkinson’s early death, in part because of the satirical nature of the work, but also because it presented a discerning view of colonial life in India.
– from the “The Coming of the Raj” exhibition UC Santa Barbara Library |
Imagine that you are a nutritionist trying to explore the nutritional content of food. What is the best way to differentiate food items? By vitamin content? Protein levels? Or perhaps a combination of both?
Knowing the variables that best differentiate your items has several uses:
1. Visualization. Using the right variables to plot items will give more insights.
2. Uncovering Clusters. With good visualizations, hidden categories or clusters could be identified. Among food items for instance, we may identify broad categories like meat and vegetables, as well as sub-categories such as types of vegetables.
The question is, how do we derive the variables that best differentiate items?
Principal Components Analysis (PCA) is a technique that finds underlying variables (known as principal components) that best differentiate your data points. Principal components are dimensions along which your data points are most spread out:
A principal component can be expressed by one or more existing variables. For example, we may use a single variable – vitamin C – to differentiate food items. Because vitamin C is present in vegetables but absent in meat, the resulting plot (below, left) will differentiate vegetables from meat, but meat items will clumped be together.
To spread the meat items out, we can use fat content in addition to vitamin C levels, since fat is present in meat but absent in vegetables. However, fat and vitamin C levels are measured in different units. To combine the two variables, we first have to normalize them, meaning to shift them onto a uniform standard scale, which would allow us to calculate a new variable – vitamin C minus fat. Combining the two variables helps to spread out both vegetable and meat items.
The spread can be further improved by adding fiber, of which vegetable items have varying levels. This new variable – (vitamin C + fiber) minus fat – achieves the best data spread yet.
While in this demonstration we tried to derive principal components by trial-and-error, PCA does this by systematic computation.
Using data from the United States Department of Agriculture, we analyzed the nutritional content of a random sample of food items. Four nutrition variables were analyzed: Vitamin C, Fiber, Fat and Protein. For fair comparison, food items were raw and measured by 100g.
Among food items, the presence of certain nutrients appear correlated. This is illustrated in the barplot below with 4 example items:
Specifically, fat and protein levels seem to move in the same direction with each other, and in the opposite direction from fiber and vitamin C levels. To confirm our hypothesis, we can check for correlations (tutorial: correlation analysis) between the nutrition variables. As expected, there are large positive correlations between fat and protein levels (r = 0.56), as well as between fiber and vitamin C levels (r = 0.57).
Therefore, instead of analyzing all 4 nutrition variables, we can combine highly-correlated variables, leaving just 2 dimensions to consider. This is the same strategy used in PCA – it examines correlations between variables to reduce the number of dimensions in the dataset. This is why PCA is called a dimension reduction technique.
Applying PCA to this food dataset results in the following principal components:
The numbers represent weights used in combining variables to derive principal components. For example, to get the top principal component (PC1) value for a particular food item, we add up the amount of Fiber and Vitamin C it contains, with slightly more emphasis on Fiber, and then from that we subtract the amount of Fat and Protein it contains, with Protein negated to a larger extent.
We observe that the top principal component (PC1) summarizes our findings so far – it has paired fat with protein, and fiber with vitamin C. It also takes into account the inverse relationship between the pairs. Hence, PC1 likely serves to differentiate meat from vegetables. The second principal component (PC2) is a combination of two unrelated nutrition variables – fat and vitamin C. It serves to further differentiate sub-categories within meat (using fat) and vegetables (using vitamin C).
Using the top 2 principal components to plot food items results in the best data spread thus far:
Meat items (blue) have low PC1 values, and are thus concentrated on the left of the plot, on the opposite side from vegetable items (orange). Among meats, seafood items (dark blue) have lower fat content, so they have lower PC2 values and are at the bottom of the plot. Several non-leafy vegetarian items (dark orange), having lower vitamin C content, also have lower PC2 values and appear at the bottom.
Choosing the Number of Components. As principal components are derived from existing variables, the information available to differentiate data points is constrained by the number of variables you start with. Hence, the above PCA on food items only generated 4 principal components, corresponding to the original number of variables in the dataset.
Principal components are also ordered by their effectiveness in differentiating data points, with the first principal component doing so to the largest degree. To keep results simple and generalizable, only the first few principal components are selected for visualization and further analysis. The number of principal components to consider is determined by something called a scree plot:
A scree plot shows the decreasing effectiveness of subsequent principal components in differentiating data points. A rule of thumb is to use the number of principal components corresponding to the location of a kink. In the plot above, the kink is located at the second component. This means that even though having three or more principal components would better differentiate data points, this extra information may not justify the resulting complexity of the solution. As we can see from the scree plot, the top 2 principal components already account for about 70% of data spread. Using fewer principal components to explain the current data sample better ensures that the same components can be generalized to another data sample.
Maximizing Spread. The main assumption of PCA is that dimensions that reveal the largest spread among data points are the most useful. However, this may not be true. A popular counter example is the task of counting pancakes arranged in a stack, with pancake mass representing data points:
To count the number of pancakes, one pancake is differentiated from the next along the vertical axis (i.e. height of the stack). However, if the stack is short, PCA would erroneously identify a horizontal axis (i.e. diameter of the pancakes) as a useful principal component for our task, as it would be the dimension along which there is largest spread.
Interpreting Components. If we are able to interpret the principal components of the pancake stack, with intelligible labels such as “height of stack” or “diameter of pancakes”, we might be able to select the correct principal components for analysis. However, this is often not the case. Interpretations of generated components have to be inferred, and sometimes we may struggle to explain the combination of variables in a principal component.
Nonetheless, having prior domain knowledge could help. In our example with food items, prior knowledge of major food categories help us to comprehend why nutrition variables are combined the way they are to form principal components.
Orthogonal Components. One major drawback of PCA is that the principal components it generates must not overlap in space, otherwise known as orthogonal components. This means that the components are always positioned at 90 degrees to each other. However, this assumption is restrictive as informative dimensions may not necessarily be orthogonal to each other:
To resolve this, we can use an alternative technique called Independent Component Analysis (ICA).
ICA allows its components to overlap in space, thus they do not need to be orthogonal. Instead, ICA forbids its components to overlap in the information they contain, aiming to reduce mutual information shared between components. Hence, ICA’s components are independent, with each component revealing unique information on the data set.
Information has thus far been represented by the degree of data spread, with dimensions along which data is more spread out being more informative. This is may not always be true, as seen from the pancake example. However, ICA is able to overcome this by taking into account other sources of information apart from data spread.
Therefore, ICA may be a backup technique to use if we suspect that components need to be derived based on information beyond data spread, or that components may not be orthogonal.
PCA is a classic technique to derive underlying variables, reducing the number of dimensions we need to consider in a dataset. In our example above, we were able to visualize the food dataset in a 2-dimensional graph, even though it originally had 4 variables. However, PCA makes several assumptions, such as relying on data spread and orthogonality to derive components. On the other hand, ICA is not subjected to these assumptions. Therefore, when in doubt, one could consider running a ICA to verify and complement results from a PCA.
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This lesson can serve as a review for advanced students or as a culmination of a unit on news gathering for beginners. Before this lesson, students should generate story ideas for a topical, in-depth or news feature story to reinforce effective reporting practice. Students will identify the types of interviews they will conduct, perform research to build knowledge of their story topic and/or sources, select appropriate sources, plan questions, conduct the interviews and prepare interview transcripts. Students will evaluate their own performance and also will have an editor and adviser perform an evaluation using a rubric.
- Students will recognize the various ways to gather information for a story and choose the types that best suits their story coverage.
- Students will effectively perform research on their topic and/or their sources in order to build a strong foundation of knowledge prior to interviewing.
- Students will use proper etiquette in setting up interviews, taking into account the schedule and environment of the source(s).
- Students will demonstrate proper interviewing techniques such as listening, rephrasing, and asking follow up questions.
- Students will develop a hierarchy of sources that best fits their story. Here, varying perspectives and experiences are considered. Expert sources are used.
- Students will create a transcription of their interviews and reliable research information with attribution that provides needed information to compose an in-depth news or news feature story.
Common Core Standards
|CCSS.ELA-Literacy.CCRA.W.8||Gather relevant information from multiple print and digital sources, assess the credibility and accuracy of each source, and integrate the information while avoiding plagiarism.|
|CCSS.ELA-Literacy.CCRA.W.10||Write routinely over extended time frames (time for research, reflection, and revision) and shorter time frames (a single sitting or a day or two) for a range of tasks, purposes, and audiences.|
|CCSS.ELA-Literacy.CCRA.SL.2||Integrate and evaluate information presented in diverse media and formats, including visually, quantitatively, and orally.|
|CCSS.ELA-Literacy.CCRA.L.1||Demonstrate command of the conventions of standard English grammar and usage when writing or speaking.|
|CCSS.ELA-Literacy.CCRA.L.2||Demonstrate command of the conventions of standard English capitalization, punctuation, and spelling when writing.|
|CCSS.ELA-Literacy.CCRA.L.3||Apply knowledge of language to understand how language functions in different contexts, to make effective choices for meaning or style, and to comprehend more fully when reading or listening.|
Flexible. Two 50-minute class periods to review reporting basics and group story planning. An additional two to four weeks to conduct research, establish sources, conduct interviews and transcribe information and for peer and adviser assessment.
Handout: Planning the interview (optional)
Handout: News gathering checklist
Handout: Online research resources (Resources for Journalistic Research)
Equipment for audio or video recording (as needed)
Internet and database access
Handout: Using databases
Handout: Reaction quotes activity (optional)
1. Prepare – 5 minutes
Prior to this lesson, students should have one or more story ideas already for a news feature or in-depth story. For some topics, teachers or editors may prefer that students work in groups to cover multiple angles. If this is the case, group the students in their reporting groups. If not, divide students into random groups of three or four for discussion.
2. Review and discussion — 35 minutes
Use the slideshow to review the basics of reporting and interviewing. Students should have some experience with news writing. This lesson advances their use of news gathering skills to cover an in-depth news or news feature story.
The purpose of this presentation is to help students to think about how to research and interview for an upcoming writing assignment. Within the slideshow, there are five discussion questions for reflection and preliminary planning. At these intervals, students will break into their groups to discuss what they will do for their specific stories, and write short answers to the questions for an exit ticket at the end of class.
At one point in the slideshow, reference is made to the handout “Resources for Journalistic Research.” Make a class set or have this available to students digitally.
Alternative note-taking option: For beginners and students who need additional assistance using a graphic organizer or planner, use the “Planning the interview” handout for use with the slideshow presentation. This may be assigned as homework.
3. Assessment — 10 minutes
Ask a spokesperson for each group to give a short review of the discussions on research plans, source lists and interview plans within their groups.
Students should turn in their answers individually to the discussion questions as an exit ticket. Check and return at next class. (Record for a daily grade if needed.)
Alternative assessment: Assign the “Planning the interview” handout as homework.
1. Brainstorm, research and adviser conference
Students working in teams to cover a story in multiple angles may need additional time for brainstorming and planning together. They should think of in-depth, enterprise-type stories that go beyond the basic news format. Teams should start listing sources, angles and potential questions and choose a team leader who can serve as a peer editor for the package. They may use the Planning the Interview handout to facilitate this brainstorm.
Once brainstorming is done, students should begin researching using the Internet and available databases on computers, phones or tablets. Or allow students to work on a different assignment while the teacher meets in small groups.
Regardless of the staff structure, have each student or group check in with you privately about their story ideas and research/reporting approach. Provide feedback on sources, questions, angles and any other information.
During the conference, pass out the “News gathering checklist” and explain that it will be used to evaluate their reporting on their story.
Project time and activities — varies, from two to four weeks
For the next week or more (as long as the teacher, editors or production schedule allows), students will perform research, establish sources, conduct interviews and transcribe information.
As students prepare their background materials, they should use the “Using databases for in-depth reporting” worksheet to log their research and how it relates to their story. Students must find at least one piece of information that they can use in their story. Have students place their findings in the table and use it to check off that item on the “News gathering checklist.” (It may be easier to make this available to students in a shared drive.)
Optional use: Beginning students and those who need additional support can use the “Reaction quotes worksheet” to log especially colorful or pertinent quotations discovered in their news gathering.
After a designated deadline, students should perform a self-evaluation of their work using the “News gathering checklist” and collect all required supporting materials. Then, peer evaluation with an editor or team leader should occur. Finally, student-teacher evaluation should occur using the checklist and supporting materials as required in the checklist.
This lesson ends with the collection of information for an in-depth story. To complete the story, go to Revising and editing news stories in the Writing Module.
While this lesson is intended for advanced reporters and staff reporters, it may be used as an advanced lesson in a beginning class or as a challenge to honors students. A variety of organizers and checklists are provided to help students keep track of what is required and log information as they find it. |
Reflection nebula are light reflections. Usually caused by a pairing of two key things: stars and nearby dust, reflection nebula are most frequently blue in color, however they can also be orange, yellow, or reddish, depending on the color of the starlight being reflected. Reflection nebula are usually fairly small, however Orion Nebula, the Great Nebula, is one of the largest in the sky (and it so happens to also be comprised of emission nebula and dark nebula as well.)
Dark nebula are light absorbers, patches and filaments and swaths of dust, often forming gigantic dust lanes in our galaxy. Formed of black body particles…dust, of any range of variety, permeate our galaxy and other galaxies. The dust of dark nebula are generally the medium that gives rise to reflection nebula, as the dist reflects the light of nearby stars. Dark nebula are often invisible to the astronomer, as they frequently exist in regions of our galaxy backed by the blackness of interstellar and even intergalactic space. Dark nebula are usually revealed by the light behind them…the densely packed stars of the milky way, or that of a nearby nebula set behind.
Currently no dark nebula images.
SNRs & Planetary Nebula
Planetary nebula are interesting and usually quite unique objects in space. Frequently forming bubble shapes, often whispy and usually ill-defined, sometimes measurably fluctuating in size and shape over relatively short periods of time (often a matter of mere years), planetary nebula are usually thought to be the remnants of stellar explosions, or supernova remnants (SNRs)…but could also be caused by other forces.
Currently no planetary nebula images. |
Let's begin to work and see the different things we can do with Word.
First, let's write something in our worksheet. This time, we will use the Print Layout viewing option.
For this example, I will use a small segment from the book "Handbook for the Warriors of Light" by Paulo Coelho. (you may use whatever you like)
When we are writing a phrase and we need to go to the next line, we just have to press Enter on our keyboard. This will take the cursor to the beginning of a new line.
We keep writing, and as we move forward, we notice the cursor indicating where we are. This helps us when we are lost.
Well, this is the way my finished text looks like.
If we look at the bottom of the screen, you will see the current state of our document.
In this example, we have a document of 1 page. We also have 51 written words in it. |
3D printing or additive manufacturing (AM) is the capability of printing three dimensional objects, which can take any shape, form or size.
To create the objects, a printer runs an additive process, which essentially lays down several 0.1mm layers of a given material (such as plastic, elasto plastic, PLA, acrylate, food and in the future, even human tissue) on top of each other’s until the product takes full shape.
The process usually starts with the digital version of the object designed on a 3D printing software such as CAD, SketchUp or Solidworks.
However, 3D printing is much more than this and has several different technologies under its umbrella. The most used ones are selective laser sintering (SLS), fused deposition modelling (FDM) and stereolithography (SLA).
According to the Standard Terminology for Additive Manufacturing Technologies, developed by the American Society for Testing and Materials (ASTM), there are seven categories for 3D printing processes.
These are vat photopolymerisation, material jetting, binder jetting, material extrusion, powder bed fusion, sheet lamination, and directed energy deposition.
Vat photopolymerisation, for example, uses mostly the stereolithography technology. A printer working on vat photopolymerisation has a container filled with photopolymer resin which becomes solid has it is exposed to UV light.
With the material jetting method, printing material is applied in droplets through a small diameter nozzle. The material is again injected layer by lawyer and becomes hard as UV light is applied.
The binder jetting process uses powder and liquid glue to create the three-dimensional object. When printing, powder is applied in equal layers and binder is injected through jet nozzles to glue the powder particles. |
A base (A) that is found in DNA, only bonds with Thymine (T) and this pairing forms part of the rungs of DNA
Reproduction of identical offspring from a single parent. No gametes are involved (e.g fission in bacteria, spores)
Thread-like structures bearing genes that are found in the nucleus of a cell. Visible during the prophase of cell division
Deoxyribonucleic acid. A molecule found in the nucleus of cells which codes for an individuals genetic makeup.
Are proteins that act as biological catalyst in living organisms. They control the rate of reactions
A sex cell: Ovum and sperm in animals or ovule and pollen grain in plants. A cell that has to join with another gamete to form a zygote before further development can occur
A base that is found in DNA. Guanine (G) will only bond with Cytosine (C) and this pairing forms part of the 'rungs' of DNA.
Having two identical alleles for a particular gene; breeds true when crossed with genetically identical organisms
Photograph of individual chromosomes of a cell arranged in pairs and showing their number, size and shape
The type of cell division which produces sex cells/gametes. In animals occurs in ovaries/testes. Process where diploid nucleus divides TWICE to produce four haploid, genetically different nuclei
A molecule containing a sugar-phosphate-base, found in DNA. Nuceotide bases pair to form DNA
The female organ that produces female gametes - eggs. Eggs are used in sexual reproduction in both plants and animals
Molecules that contain amino acids. They are found in all living organisms. There are many different types and all have important roles in living systems.
A diagram used to predict the phenotype and genotype ratios of offspring by showing how alleles combine together during fertilisation
DNA replication by 'unzipping' a DNA molecule followed by pairing up of nucleotides to produce two new DNA molecules each with one origional and one newly synthesised strand of DNA
Form of reproduction involving the fusion of two gametes from two parents. Produces a variation in the offspring
The male organ that produces male gametes - sperm. Sperm are used in sexual reproduction in animals
A fertilised egg. A single cell containing chromosomes from male and female gametes at the time/point of fertilisation
Used to find out the genotype of an individual. We cross the 'unknown' with a homozygous recessive and observe phenotypes of offspring.
Genotype and Phenotype ratio
Using the punnet square we write down the number/4 and % of individuals showing particular genotypes and phenotypes. i.e Genotype 2 BB: 2 Bb. Phenotype (100%) All Brown Eyed.
How is variation introduced in Meiosis?
Introduced through 1) independant assortment (each chromosome is organised into gametes independantly of each other chromosome), 2) Crossing over (homologous chromosomes - one from mum, one from dad - can switch genetic information creating chromsomes with new arrangment of genes) 3) Mutations - DNA can replicate with some errors 4) Fertilision - gametes produced in Meiosis come together to produce new/novel combinations.
Pair of chromosomes (same length, gene positions), i.e Chromosome #3, one comes from Mum, one from Dad.
Each chromosome is organised into gametes independantly of each other chromosome
This is when homologous chromosomes (one from mum, one from dad)can switch genetic information when they line up during cell division, this creates chromosomes with different arrangment of genes to parent chromosomes.
Can be either somatic (in body cells) or gametic (in gametes). Only Gametic mutations are passed on. This creates variation in a population. Natural selection acts on these new traits.
Explain what Natural Selection is and how it leads to evolution
More individuals are born than can survive. There is natural VARIATION in populations (not all the same). Some are BETTER SUITED to environment than others. Individuals COMPETE for resources. Those that are better suited produce MORE OFFSPRING. There genes are represented in greater proportion. Environment can change. This leads to gradual CHANGES (evolution) sometimes new species are formed. |
Television pictures contain a lot of information and often have to be reduced before being recorded or transmitted. This is partly done by a technique known as compression. Compression techniques take away some of the information which is either redundant or has little effect on how we percieve the compressed image. Compression techniques are more aggressive if the final viewing platform is say a mobile phone and far less aggressive for transmission as a broadcast quality high definition television signal .
Compression ratio is a measure of the amount of compression taking place and refers to the relationship between the number of bits entering a 'compression engine' and the number of bits coming out the other side.
So if a fully sampled uncompressed 270 Mbps signal goes into a compressor and 50 Mbps comes out of the other side, then the compression ratio is 270/50 or about 5.5:1
Other techniques for reducing the amount of data are bit depth reduction and chroma subsampling. These simply remove some data and do not cause any compression. The combined effect of data reduction and compression is know as a codec.
Now - Lots of codecs use all 3 techniques - The DV codec for example goes from 10 bits sampling to 8 (bit depth reduction) then 4:2:2 to 4:2:0 (chroma sub-sampling) and then compresses the result to create an output bit rate of 25Mbps. - so the ratio of input bits to output bits is 270/25 or close to 11 to 1. (Partly 'data reduction' and partly compression).
Most people will just say DV is about 10:1 compressed - and frankly that is good enough for most purposes.
So when we talk about compression or compression ratio, it doesn't just refer to the compression part of the codec but rather the overall combined effect of data reduction and compression. Simply the ratio of what goes in to what comes out. |
Radio transmitter design
A radio transmitter is an electronic device which, when connected to an antenna, produces an electromagnetic signal such as in radio and television broadcasting, two way communications or radar. Heating devices, such as a microwave oven, although of similar design, are not usually called transmitters, in that they use the electromagnetic energy locally rather than transmitting it to another location.
A radio transmitter design has to meet certain requirements. These include the frequency of operation, the type of modulation, the stability and purity of the resulting signal, the efficiency of power use, and the power level required to meet the system design objectives. High-power transmitters may have additional constraints with respect to radiation safety, generation of X-rays, and protection from high voltages.
Typically a transmitter design includes generation of a carrier signal, which is normally sinusoidal, optionally one or more frequency multiplication stages, a modulator, a power amplifier, and a filter and matching network to connect to an antenna. A very simple transmitter might contain only a continuously running oscillator coupled to some antenna system. More elaborate transmitters allow better control over the modulation of the emitted signal and improve the stability of the transmitted frequency. For example the Master Oscillator-Power Amplifier (MOPA) configuration inserts an amplifier stage between the oscillator and the antenna. This prevents changes in the loading presented by the antenna from altering the frequency of the oscillator.
Determining the frequency
Fixed frequency systems
For a fixed frequency transmitter one commonly used method is to use a resonant quartz crystal in a Crystal oscillator to fix the frequency. Where the frequency has to be variable, several options can be used.
Variable frequency systems
- An array of crystals – used to enable a transmitter to be used on several different frequencies; rather than being a truly variable frequency system, it is a system which is fixed to several different frequencies (a subset of the above).
- Variable-frequency oscillator (VFO)
- Phase-locked loop frequency synthesiser
- Direct digital synthesis
While modern frequency synthesizers can output a clean stable signal up through UHF, for many years, especially at higher frequencies, it was not practical to operate the oscillator at the final output frequency. For better frequency stability, it was common to multiply the frequency of the oscillator up to the final, required frequency. This was accommodated by allocating the short wave amateur and marine bands in harmonically related frequencies such as 3.5, 7, 14 and 28 MHz. Thus one crystal or VFO could cover several bands. In simple equipment this approach is still used occasionally.
If the output of an amplifier stage is simply tuned to a multiple of the frequency with which the stage is driven, the stage will give a large harmonic output. Many transmitters have used this simple approach successfully. However these more complex circuits will do a better job. In a push-push stage, the output will only contain even harmonics. This is because the currents which would generate the fundamental and the odd harmonics in this circuit are canceled by the second device. In a push-pull stage, the output will contain only odd harmonics because of the canceling effect.
Adding modulation to the signal
The task of a transmitter is to convey some form of information using a radio signal (carrier wave) which has been modulated to carry the intelligence. The RF generator in a microwave oven, electrosurgery, and induction heating are similar in design to transmitters, but usually not considered as such in that they do not intentionally produce a signal that will travel to a distant point. Such RF devices are required by law to operate in an ISM band where interference to radio communications will not occur. Where communications is the object, one or more of the following methods of incorporating the desired signal into the radio wave is used.
When the amplitude of a radio frequency wave is varied in amplitude in a manner which follows the modulating signal, usually voice, video or data, we have Amplitude modulation (AM).
Low level and high level
In low level modulation a small audio stage is used to modulate a low power stage. The output of this stage is then amplified using a linear RF amplifier. The great disadvantage of this system is that the amplifier chain is less efficient, because it has to be linear to preserve the modulation. Hence high efficiency class C amplifiers cannot be employed, unless a Doherty amplifier, EER (Envelope Elimination and Restoration) or other methods of predistortion or negative feedback are used. High level modulation uses class C amplifiers in a broadcast AM transmitter and only the final stage or final two stages are modulated, and all the earlier stages can be driven at a constant level. When modulation is applied to the plate of the final tube, a large audio amplifier is needed for the modulation stage, equal to 1/2 of the DC input power of the modulated stage. Traditionally the modulation is applied using a large audio transformer. However many different circuits have been used for high level AM modulation. See Amplitude Modulation.
Types of AM modulators
A wide range of different circuits have been used for AM. While it is perfectly possible to create good designs using solid-state electronics, valved (tube) circuits are shown here. In general, valves are able to easily yield RF powers far in excess of what can be achieved using solid state. Most high-power broadcast stations below 3 MHz use solid state circuits, but higher power stations above 3 MHz still use valves.
Plate AM modulators
High level plate modulation consists of varying the voltage on the plate (anode) of the valve so that it swings from nearly zero to double the resting value. This will produce 100% modulation and can be done by inserting a transformer in series with the high voltage supply to the anode so that the vector sum of the two sources, (DC and audio) will be applied. A disadvantage is the size, weight and cost of the transformer as well as its limited audio frequency response, especially for very powerful transmitters.
Alternatively a series regulator can be inserted between the DC supply and the anode. The DC supply provides twice the normal voltage the anode sees. The regulator can allow none or all of the voltage to pass, or any intermediate value. The audio input operates the regulator in such a way as to produce the instantaneous anode voltage needed to reproduce the modulation envelope. An advantage of the series regulator is that it can set the anode voltage to any desired value. Thus the power output of the transmitter can be easily adjusted, allowing the use of Dynamic Carrier Control. The use of PDM switching regulators makes this system very efficient, whereas the original analog regulators were very inefficient and also non linear. Series PDM modulators are used in solid state transmitters also, but the circuits are somewhat more complex, using push pull or bridge circuits for the RF section.
These simplified diagrams omit such details as filament, screen and grid bias supplies, and the screen and cathode connections to RF ground.
Screen AM modulators
Under carrier conditions (no audio) the stage will be a simple RF amplifier where the screen voltage is set lower than normal to limit the RF output to about 25% of full power. When the stage is modulated the screen potential changes and so alters the gain of the stage. It takes much less audio power to modulate the screen, but final stage efficiency is only about 40%, compared to 80% with plate modulation. For this reason screen modulation was used only in low power transmitters and is now effectively obsolete.
Several derivatives of AM are in common use. These are
SSB, or SSB-AM single-sideband full carrier modulation, is very similar to single-sideband suppressed carrier modulation (SSB-SC). It is used where it is necessary to receive the audio on an AM receiver, while using less bandwidth than with double sideband AM. Due to high distortion, it is seldom used. Either SSB-AM or SSB-SC are produced by the following methods.
Using a balanced mixer a double side band signal is generated, this is then passed through a very narrow bandpass filter to leave only one side-band. By convention it is normal to use the upper sideband (USB) in communication systems, except for amateur radio when the carrier frequency is below 10 MHz. There the lower side band (LSB) is normally used.
The phasing method for the generation of single sideband signals uses a network which imposes a constant 90° phase shift on audio signals over the audio range of interest. This was difficult with analog methods but with DSP is very simple.
These audio outputs are each mixed in a linear balanced mixer with a carrier. The carrier drive for one of these mixers is also shifted by 90°. The outputs of these mixers are added in a linear circuit to give the SSB signal by phase cancellation of one of the sidebands. Connecting the 90° delayed signal from either the audio or the carrier (but not both) to the other mixer will reverse the sideband, so either USB or LSB is available with a simple DPDT switch.
Vestigial-sideband modulation (VSB, or VSB-AM) is a type of modulation system commonly used in analogue TV systems. It is normal AM which has been passed through a filter which reduces one of the sidebands. Typically, components of the lower sideband more than 0.75 MHz or 1.25 MHz below the carrier will be heavily attenuated.
This interrupted carrier may be analyzed as an AM-modulated carrier. On-off keying produces sidebands, as expected, but they are referred to as "key-clicks". Shaping circuits are used to turn the transmitter on and off smoothly instead of instantly in order to limit the bandwidth of these sidebands and reduce interference to adjacent channels.
Angle modulation is the proper term for modulation by changing the instantaneous frequency or phase of the carrier signal. True FM and phase modulation are the most commonly employed forms of analogue angle modulation.
Direct FM (true Frequency modulation) is where the frequency of an oscillator is altered to impose the modulation upon the carrier wave. This can be done by using a voltage-controlled capacitor (Varicap diode) in a crystal-controlled oscillator or frequency synthesiser. The frequency of the oscillator is then multiplied up using a frequency multiplier stage, or is translated upwards using a mixing stage, to the output frequency of the transmitter. The amount of modulation is referred to as the deviation, being the amount that the frequency of the carrier instantaneously deviates from the centre carrier frequency.
Indirect FM employs a varicap diode to impose a phase shift (which is voltage-controlled) in a tuned circuit that is fed with a plain carrier. This is termed phase modulation. In some indirect FM solid state circuits, an RF drive is applied to the base of a transistor. The tank circuit (LC), connected to the collector via a capacitor, contains a pair of varicap diodes. As the voltage applied to the varicaps is changed, the phase shift of the output will change.
Phase modulation is mathematically equivalent to direct Frequency modulation with a 6dB/octave high-pass filter applied to the modulating signal. This high-pass effect can be exploited or compensated for using suitable frequency-shaping circuitry in the audio stages ahead of the modulator. For example, many FM systems will employ pre-emphasis and de-emphasis for noise reduction, in which case the high-pass equivalency of phase modulation automatically provides for the pre-emphasis. Phase modulators are typically only capable of relatively small amounts of deviation while remaining linear, but any frequency multiplier stages also multiply the deviation in proportion.
Transmission of digital data is becoming more and more important. Digital information can be transmitted by AM and FM modulation, but often digital modulation consists of complex forms of modulation using aspects of both AM and FM. COFDM is used for DRM broadcasts. The transmitted signal consists of multiple carriers each modulated in both amplitude and phase. This allows very high bit rates and makes very efficient use of bandwidth. Digital or pulse methods also are used to transmit voice as in cell phones, or video as in terrestrial TV broadcasting. Early text messaging such as RTTY allowed the use of class C amplifiers, but modern digital modes require linear amplification.
See also Sigma-delta modulation (∑Δ)
Amplifying the signal
For high power, high frequency systems it is normal to use valves, please see [Valve RF amplifier] for details of how valved RF power stages work. Valves are electrically very robust, they can tolerate overloads which would destroy bipolar transistor systems in milliseconds. As a result, valved amplifiers may resist mistuning, lightning and power surges better. However, they require a heated cathode which consumes power and will fail in time due to loss of emission or heater burn out. The high voltages associated with valve circuits are dangerous to persons. For economic reasons, valves continue to be used for the final power amplifier for transmitters operating above 1.8 MHz and with powers above about 500 watts for amateur use and above about 10 Kw for broadcast use.
Solid state devices, either discrete transistors or integrated circuits, are universally used for new transmitter designs up to a few hundred watts. The lower level stages of more powerful transmitters are also all solid state. Transistors can be used at all frequencies and power levels, but since the output of individual devices is limited, higher power transmitters must use many transistors in parallel, and the cost of the devices and the necessary combining networks can be excessive. As new transistor types become available and the price drops, solid state may eventually replace all valve amplifiers.
Linking the transmitter to the aerial
The majority of modern transmitting equipment is designed to operate with a resistive load fed via coaxial cable of a particular characteristic impedance, often 50 ohms. To connect the power stage of the transmitter to this coaxial cable transmission line a matching network is required. For solid state transmitters this is typically a broadband transformer which steps up the low impedance of the output devices to 50 ohms. A tube transmitter will contain a tuned output network, most commonly a PI network, that steps the load impedance which the tube requires down to 50 ohms. In each case the power producing devices will not transfer power efficiently if the network is detuned or badly designed or if the antenna presents other than 50 ohms at the transmitter output. Commonly an SWR meter and/or directional wattmeter are used to check the extent of the match between the aerial system and the transmitter via the transmission line (feeder). A directional wattmeter indicates forward power, reflected power, and often SWR as well. Each transmitter will specify a maximum allowable mismatch based on efficiency, distortion, and possible damage to the transmitter. Many transmitters have automatic circuits to reduce power or shut down if this value is exceeded.
Transmitters feeding a balanced transmission line will need a balun. This transforms the single ended output of the transmitter to a higher impedance balanced output. High power short wave transmission systems typically use 300 ohm balanced lines between the transmitter and antenna. Amateurs often use 300-450 ohm balanced antenna feeders.
Many devices depend on the transmission and reception of radio waves for their operation. The possibility for mutual interference is great. Many devices not intended to transmit signals may do so. For instance a dielectric heater might contain a 2000 watt 27 MHz source within it. If the machine operates as intended then none of this RF power will leak out. However, if due to poor design or maintenance it allows RF to leak out, it will become a transmitter or unintentional radiator.
RF leakage & shielding
All equipment using RF electronics should be inside a screened conductive box and all connections in or out of the box should be filtered to avoid the passage of radio signals. A common and effective method of doing so for wires carrying DC supplies, 50/60 Hz AC connections, audio and control signals is to use a feedthrough capacitor, whose job is to short circuit any RF on the wire to ground. The use of ferrite beads is also common.
If an intentional transmitter produces interference, then it should be run into a dummy load; this is a resistor in a screened box or can which will allow the transmitter to generate radio signals without sending them to the antenna. If the transmitter continues to cause interference during this test then a path exists by which RF power is leaking out of the equipment and this can be due to bad shielding. Such leakage is most likely to occur on homemade equipment or equipment that has been modified or had covers removed. RF leakage from microwave ovens, while rare, may occur due to defective door seals, and may be a health hazard.
Early in the development of radio technology it was recognized that the signals emitted by transmitters had to be 'pure'. Spark-gap transmitters were outlawed once better technology was available as they give an output which is very wide in terms of frequency. The term spurious emissions refers to any signal which comes out of a transmitter other than the wanted signal. In modern equipment there are three main types of spurious emissions: harmonics, out of band mixer products which are not fully suppressed and leakage from the local oscillator and other systems within the transmitter.
These are multiples of the operation frequency of the transmitter, they can be generated in any stage of the transmitter which is not perfectly linear and must be removed by filtering.
Avoiding harmonic generation
The difficulty of removing harmonics from an amplifier will depend on the design. A push-pull amplifier will have fewer harmonics than a single ended circuit. A class A amplifier will have very few harmonics, class AB or B more, and class C the most. In the typical class C amplifier, the resonant tank circuit will remove most of the harmonics, but in either of these examples, a low pass filter will likely be needed following the amplifier.
Removal of harmonics with filters
In addition to the good design of the amplifier stages, the transmitter's output should be filtered with a low pass filter to reduce the level of the harmonics. Typically the input and output are interchangeable and match to 50 ohms. Inductance and capacity values will vary with frequency. Many transmitters switch in a suitable filter for the frequency band being used. The filter will pass the desired frequency and reduce all harmonics to acceptable levels.
The harmonic output of a transmitter is best checked using an RF spectrum analyzer or by tuning a receiver to the various harmonics. If a harmonic falls on a frequency being used by another communications service then this spurious emission can prevent an important signal from being received. Sometimes additional filtering is used to protect a sensitive range of frequencies, for example, frequencies used by aircraft or services involved with protection of life and property. Even if a harmonic is within the legally allowed limits, the harmonic should be further reduced.
Oscillators and mix products
When mixing signals to produce a desired output frequency, the choice of Intermediate frequency and local oscillator is important. If poorly chosen, a spurious output can be generated. For example if 50 MHz is mixed with 94 MHz to produce an output on 144 MHz, the third harmonic of the 50 MHz may appear in the output. This problem is similar to the Image response problem which exists in receivers.
One method of reducing the potential for this transmitter defect is the use of balanced and double balanced mixers. A simple mixer will pass both of the input frequencies and all of their harmonics along with the sum and difference frequencies. If the simple mixer is replaced with a balanced mixer then the number of possible products is reduced. If the frequency mixer has fewer outputs the task of making sure that the final output is clean will be simpler.
Instability and parasitics
If a stage in a transmitter is unstable and is able to oscillate then it can start to generate RF at either a frequency close to the operating frequency or at a very different frequency. One good sign that it is occurring is if an RF stage has a power output even without being driven by an exciting stage. Output power should increase smoothly as input power is increased, although with Class C, there will be a noticeable threshold effect. Various circuits are used for parasitic suppression in a good design. Proper neutralization is also important.
Control and protection
The simplest transmitters such as RFID devices require no external controls. Simple tracking transmitters may have only an on-off switch. Many transmitters must have circuits that allow them to be turned on and off and the power output and frequency adjusted or modulation levels adjusted. Many modern multi-featured transmitters allow the adjustment of many different parameters. Usually these are under microprocessor control via multilevel menus, thus reducing the required number of physical knobs. Often a display screen provides feedback to the operator to assist in adjustments. The user friendliness of this interface will often be one of the main factors in a successful design.
Microprocessor controlled transmitters also may include software to prevent off frequency or other illegal operation. Transmitters using significant power or expensive components must also have protection circuits which prevent such things as overload, overheating or other abuse of the circuits. Overload circuits may include mechanical relays, or electronic circuits. Simple fuses may be included to protect expensive components. Arc detectors may shut off the transmitter when sparks or fires occur.
Protection features must also prevent the human operator and the public from encountering the high voltages and power which exist inside the transmitter. Tube transmitters typically use DC voltages between 600 and 30,000 volts, which are deadly if contacted. Radio frequency power above about 10 watts can cause burning of human tissue through contact and higher power can actually cook human flesh without contact. Metal shielding is required to isolate these dangers. Properly designed transmitters have doors or panels which are interlocked, so that open doors activate switches which do not allow the transmitter to be turned on when the dangerous areas are exposed. In addition, either resistors which bleed off the high voltages or shorting relays are employed to insure that capacitors do not retain a dangerous charge after turn off.
With large high power transmitters, the protective circuits can comprise a significant fraction of the total design complexity and cost.
Some RFID devices take power from an external source when it interrogates the device, but most transmitters either have self-contained batteries, or are mobile systems which typically operate directly from the 12 volt vehicle battery. Larger fixed transmitters will require power from the mains. The voltages used by a transmitter will be AC and DC of many different values. Either AC transformers or DC power supplies are required to provide the values of voltage and current needed to operate the various circuits. Some of these voltages will need to be regulated. Thus a significant part of the total design will consist of power supplies. Power supplies will be integrated into the control and protection systems of the transmitter, which will turn them on in the proper sequence and protect them from overloads. Often rather complicated logic systems will be required for these functions.
|The Wikibook Electronics has a page on the topic of: Transmitter design|
- Distributed active transformer – low-voltage transistors used to generate radio frequencies
- Citations and notes
- Rudolf F. Graf, William Sheets, Build Your Own Low-Power Transmitters: Projects for the Electronics Experimenter Newnes, 2001 ISBN 0750672447, page 2
- Ronald Kitchen, RF Radiation Safety Handbook, Butterworth Heinemann 1993, ISBN 0 7506 1712 8 Chapter 10
- some spread spectrum systems use pulses or sets of orthogonal wave forms
- Joseph J. Carr Microwave and Wireless Communication Technology, Newnes, 1997 ISBN 0750697075 page 339-341
- Pappenfus, Bruene and Schoenike Single sideband principles and circuits McGraw-Hill, 1964, chapter 6
- General information
- American Radio Relay League. (2012).The ARRL Handbook for Radio Communications.| ISBN 978-0-87259-663-4|url=http://www.arrl.org/arrl-handbook-2013
- Radio Society of Great Britain. (2005). Radio communication handbook. Potters Bar, Hertfordshire [England]: Radio Society of Great Britain. ISBN 0-900612-58-4
- Terman, Electronics and Radio Engineering. McGraw-Hill
- Frederick H. Raab, et al. (May 2003). "RF and Microwave Power Amplifier and Transmitter Technologies - Part 2". High Frequency Design: p. 22ff. http://www.scribd.com/doc/8616046/RF-Power-Amplifier-and-Transmitter-Technologies-Part2
- Historical interest
- Bucher, E. E. (1921). Practical wireless telegraphy; a complete text book for students of radio communication. New York [etc.]: Wireless Press.<Link is Broken>
- Sleeper, M. B. (1922). Design data for radio transmitters and receivers. Everyday engineering series, [no.] 6. New York: Norman W. Henley Pub.<Link is Broken> |
The sixth president of the United States (1825-1829) was born during the American Revolution in a farmhouse outside Boston in what is now Quincy. His remains were interred in a crypt of the First Parish Church (Unitarian) in Quincy with those of his wife Louisa and his parents John and Abigail, who educated him at home. His father, the coauthor of the Declaration of Independence who became the second president of the United States, taught him mathematics, languages, and classics. Both parents expected him to devote his life to public service.
At the age of ten the son accompanied his father to Europe on a diplomatic mission. John Quincy Adams attended schools in France and Holland and also served as secretary during diplomatic negotiations in Russia and Paris. He received advanced standing at Harvard College. After graduating in 1787, he studied law but found it a boring profession. President George Washington appointed him United States minister to Holland in 1794. After marriage to Louisa Catherine Johnson, he rendered further diplomatic service in Europe.
John Quincy Adams became a United States senator and boldly endorsed President Thomas Jefferson’s then controversial Louisiana Purchase from France in 1803-what is now called the world’s greatest real estate bargain. From 1803 to 1808 he also served half-time as Professor of Rhetoric and Oratory at Harvard. President James Monroe appointed him America’s first minister to Russia, 1809-1814. Then he was U.S. minister to Great Britain until appointed by President James Monroe as U.S. secretary of state, 1817-1825-now cited as possibly the greatest secretary of state of all time. By the treaty of 1819 Spain formally ceded East and West Florida to the United States. Of enduring primary importance was the enunciation of the decisive Monroe Doctrine, which closed the United States to European intervention by asserting its right of self-protection. Not without reason is Adams celebrated for the historic crystallization of U.S. foreign policy.
Nevertheless, John Quincy Adams is not known as a great president. Assailed by innumerable conflicts, he was often depressed, aloof, and angry. However, he found relief by regularly swimming nude at 5 a.m. in the Potomac River. Learning about this and recalling Adams’s repeated refusal to be interviewed by the first American professional journalist, Anne Royall is reported to have gone to the river, gathered his clothes and sat on them until she had her interview. No female is thought ever before to have interviewed a president.
After his dismal presidential years, Adams returned to greatness by being the only person to leave the White House and then serve in the U.S. House of Representatives. It was Adams who presented petitions for the abolition of slavery. It was Adams who pervasively countered Southern political power. It was Adams who constantly advocated large scale public improvements. It was Adams who repeatedly acted to enhance America’s stature in business, industry, and science.
John Quincy Adams was devout, reading three chapters of the Bible daily upon arising, thus reading the entire book each year. His poetry is often Bible-based. He was one of the founders of the Unitarian Church in the nation’s capital, but he was no ally of Ralph Waldo Emerson’s transcendentalism. Adams called the Divinity School Address crazy.
The esteemed legislator from Massachusetts collapsed in the chambers of the House of Representatives when he, “Old Man Eloquent,” was unable to speak. Two days later he died in his eighty-first year.
His writings are available in The Adams Papers, published by the Massachusetts Historical Society and Harvard University.
Excerpts from the Poetry of John Quincy Adams
O GOD, WITH GOODNESS ALL THY OWN
O God, with goodness all thy own,
In mercy cause thy face to shine;
So shall thy ways on earth be known,
Thy saving health and power divine:
O, let the gladdening nations sing,
And praise thy name with hallowed mirth,
For thou of righteousness art King,
And rulest all the subject earth.
O, let the people praise the Lord;
The people all thy praise express;
And earth her plenty shall afford,
And God, yea, our own God, shall bless;
Our God his blessing shall bestow;
His power, his goodness, shall appear;
And all the ends of earth shall know
And worship him with holy fear.
TO THE SUN-DIAL
Thou silent herald of Time’s silent flight!
Say could’st thou speak, what warning voice were thine?
Shade, who canst only show how others shine!
Dark, sullen witness of resplendent light
In day’s broad glare, and when the noontide bright
Of laughing fortune sheds the ray divine,
Thy ready favor cheers us–but decline
the clouds of morning and the gloom of night.
Yet are thy counsels faithful, just, and wise;
They bid us seize the moments as they pass–
Snatch the retrieveless sunbeam as it flies,
Nor lose one sand of life’s revolving glass–
Aspiring still, with energy sublime,
By virtuous deeds to give eternity to Time.
A Note on Unitarian Connections
Both John Quincy Adams and John C. Calhoun were founders of All Souls Unitarian Church in Washington, D.C. |
Most stories follow the same basic structure. They start by introducing the characters, setting, and central conflict (exposition), contain events that build in scope (rising action) until the "big event" (climax), after which, various conflicts are dealt with (falling action) until the end, where the lessons are learned or all conflicts are dealt with (resolution). These worksheets will have your students mapping essential elements of children's stories and fables to this pattern. Answer keys are provided as you might find them very helpful when grading.
Fun Project Idea: Have your students bring in their favorite books or stories and perform the same exercise, and present the result to the class. |
Trying to see the world through someone else's eyes is a great way to build empathy and understanding between people. Turns out, this approach -- when taken literally -- also works with robots. Researchers from the University of Bourgogne, University of Trento, and their colleagues used a head-mounted display to put people "inside" a robot and then studied their "likeability and closeness towards the robot."
"We have demonstrated that by 'beaming' a participant into a robot we can change his or her attitude towards the robot," says University of Trento psychologist Francesco Pavani.
"By 'beaming', we mean that we gave the participants the illusion that they were looking through the robot's eyes, moving its head as if it were their head, look in the mirror and see themselves as a robot."
"Unlike exercises in which the participants couldn't t move the robot's head or do that in a coordinated manner with other body movements, in our study the experience of walking in the shoes of a robot led the participants to adopt a friendlier attitude, to perceive them as socially closer."
From the abstract of their scientific paper published in Scientific Reports:
Read the rest
When participant’ and robot’s head movements were correlated, participants felt that they were incorporated into the robot with a sense of agency. Critically, the robot they embodied was judged more likeable and socially closer. Remarkably, we found that the beaming experience with correlated head movements and corresponding sensation of embodiment and social proximity, was independent of robots’ humanoid’s appearance. |
Math 6-8: The Standards in Practice
6-12 Teachers, Teacher Leaders, Professional Development Coordinators, Administrators
This two hour workshop illustrates how teachers can weave the Mathematical Practice Standards with the Content Standards. Participants will engage in a mathematically rigorous lesson from the Mathematics Assessment Project: Interpreting Distance-Time Graphs.
Suggested Use for these Documents:Teacher Leaders and Professional Development Coordinators to use this PowerPoint and these documents to run a workshop that will illustrate how to implement an exemplar CCSS-M lesson. Familiarity with the Practice and Content Standards is a pre-requisite.
- Math 6-8: The Standards in Practice: A Common Core Lesson PowerPoint and facilitator’s guide
- Poster paper, markers, tape, scissors, internet connection, projector
- Handouts listed in the facilitator’s guide
Send questions and comments to:
This work is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License |
What are Phytoplankton?
A previous version of this article was published in 1999. An archived version is available as a PDF file.
Derived from the Greek words phyto (plant) and plankton (made to wander or drift), phytoplankton are microscopic organisms that live in watery environments, both salty and fresh.
Some phytoplankton are bacteria, some are protists, and most are single-celled plants. Among the common kinds are cyanobacteria, silica-encased diatoms, dinoflagellates, green algae, and chalk-coated coccolithophores.
Like land plants, phytoplankton have chlorophyll to capture sunlight, and they use photosynthesis to turn it into chemical energy. They consume carbon dioxide, and release oxygen. All phytoplankton photosynthesize, but some get additional energy by consuming other organisms.
Phytoplankton growth depends on the availability of carbon dioxide, sunlight, and nutrients. Phytoplankton, like land plants, require nutrients such as nitrate, phosphate, silicate, and calcium at various levels depending on the species. Some phytoplankton can fix nitrogen and can grow in areas where nitrate concentrations are low. They also require trace amounts of iron which limits phytoplankton growth in large areas of the ocean because iron concentrations are very low. Other factors influence phytoplankton growth rates, including water temperature and salinity, water depth, wind, and what kinds of predators are grazing on them.
When conditions are right, phytoplankton populations can grow explosively, a phenomenon known as a bloom. Blooms in the ocean may cover hundreds of square kilometers and are easily visible in satellite images. A bloom may last several weeks, but the life span of any individual phytoplankton is rarely more than a few days. |
i) Aardvark; an aardvark weighs between 40-82kg on average. The animal has a long nose, squared-off head and tapered tail which has delicate built extensions in comparison with the massive body and the muscular limbs which are armed with great nail digits. The fur on many old individuals can become heavily abraded but young animals are well furred. The aardvark is a shy nocturnal animal and rarely seen. Its burrows, spade-like scratching and tracks are more commonly seen than the animal itself. The snout is not at all pig-like, being soft, mobile, rounded and furry, with dense hair around the nostrils.
The aardvark is normally rare or absent in rain forest. It is common in areas with abundant ants, termites and beetle larvae. It digs harems which may be far from foraging areas. This mammal depends on termites, ants and larvae which are foraged at night, beginning an hour or two after dusk. Most food is found on a very close to the surface but sub-terranean termitaries, ants nests and beetle caches may be extensively excavated. Insects are swept into the small mouth by the long sticky tongue.
The aardvark is solitary but females sometimes are accompanied by one or two young Large warrens may be used by more than two or three animals. The only recorded sounds are a grunt and in extreme fear a bleat. The aardvark lives up to 18 years.
Location; – Queen Elizabeth N.P
– L. Mburo N.P
ii) Golden mole; it is one of sub-terranean mammals with shiny coats of very dense fur and streamlined, formless appearance. All moles have a blunt, bare nose, digging fore legs with one or more greatly enlarged claws and less developed hind legs. They have no visible eyes, ears or tails. They live in various habitats where some have been seen to catch food on the surface but most species obtain the greater part of their invertebrate diet underground. They make various types of mole hills and sub-surface tunnels that betray their presence.
iii) Hyraxes; these are rabbit-sized, woolly and brown, with large mouthed, deep-jawed heads and rubbery blunt-fingered hands and feet. Skull and teeth remain the most reliable guide to genera but each occupies a different niche with a distinct diet and each species has loud and highly distinctive vocalization. Hyraxes are mainly diurnal animals.
These animals mainly live mostly in escarpments, rock outcrops, evergreen thickets, moist savannahs and river banks. Hyraxes mainly depend on leaves, fruits, stems, twigs and herbs as their basic diet. The mammals are known to live in single colonies and are aggressive d during the mating season.
iv) Elephant; a female elephant weighs between 2200-3500kg while a male one is between 4000 and 6500kg. An elephant is the largest land animal which can be identified by a trunk, tusks, large ears and pillar-like legs. It has pigmented skin which varies from dense black to pale grey. New born elephants are often very hairy. The large, round ears are not only for sound catching dishes but also as a cooling mechanism.
Elephants normally prefer grassland and savannah areas as their habitats. These mammals entirely depend on grass as their staple diet. Tree branches can supplement grass during dry season. The central unit in an elephant society is the mother and her offspring. Female elephants are not able to conceive until 8 years of age (20 at latest) but once they become mothers they soon become unit leaders. Gestation normally lasts 650-660 days and very rarely 2 young ones are born. Mothers pay maximum attention to their infants all the time. Elephants are thought to live up to 65 years.
Location; – Queen Elizabeth N.P
-Murchison Falls N.P
Odd – Toed Ungulates
- i) Zebra; in Uganda, the common zebra is the most seen animal. On average, a female mammal weighs 175-250kg while a male one is between 220-322kg. It is a muscular horse with relatively short neck and sturdy legs. The stripes are subject to much regional and individual variation.
Grasslands, steppes, savannahs and woodlands form favorable habitats for these animals. They are totally dependent on frequent drinking. They prefer firm ground underfoot so may move off sump lands in the wet season or during flooding.
Grass of the most available species form a basic diet for zebras. They mow short lawns close to the roots but are equally able to take taller flowering grasses. Water shortage may concentrate zebra populations around available water holes during the dry seasons.
Up to 6 females and their young live in very stable harems where they are subject to low-key but continuous coercion by the harem stallion. Zebras have gestation period of 12 months where a foal (2 rarely) is born. The foal sucks the milk for up to 6 months before grazing. Zebras are known to live for 40 years.
Location; L. Mburo N.P
- ii) Rhinoceros; these are the second largest land animals only surpassed by elephants in bulk and weight. They have relatively short, powerfully muscled legs a short neck and a massive head, armed with a nasal horn or horns. Both black and white rhinos used to exist in Uganda until 1980s when they were poached during the political turmoil. The Ugandan government imported them from neighbouring Kenya and are harbored at Ziwa Rhino Sanctuary in Nakasongola.
Black Rhino; it weighs between 700-1000kg. Its thickest skin forms inflexible plates over the shoulders, haunches, sides, fore head and cheeks. Skin around the muzzle, eyes, ears, undersides and legs is thinner and more flexible. The head has a short fore head and a very muscular, mobile mouth ending in a sharply pointed upper lip. It likes favorable edges of thickets and savannahs with areas of short woody re-growth and numerous scrubs and herbs as its habitat
It’s a low –level browser e.g. (leaves, twigs and branches) typically in acacia, thicket, hard pan and riverine plant communities. Salt is a major attraction of rhinos. They can go for 5 days without water. A female with her young is a basic social unit. Adult females form temporary associations but aggression is elicited by total strangers. Home ranges can cover over 130km sq. but some are as small as 2.6km sq. Overtly territorial behavior is also variable. Males in low density areas are more likely to b e aggressive.
Even – Toed Ungulates
- i) Hippopotamus; a female hippopotamus weighs between 510-2500kg while a male one weighs between 650-3200kg. It has eyes, ears and nostrils on top of the head. The hippo’s main color is smooth, shiny hide purplish grey to blue- black. Underside, eye rims, ears and mouth show variable expanses of pink. Hide glands exude a blood-like fluid. Males have large canines and incisor teeth set in massive jaws and skull and also a huge jowl and thickened neck. Hippos are solitary grazers on land by night, a vocal, densely social and sedentary willower by day. Both creeping and tussock grasses form basic diet of these animals. Females accompanied by up to 4 successive offspring are only stable social unit. Largest males occupy narrow strips of water and land along the fore shore. Here they defend exclusive mating rights but tolerate most subordinate males. Large groups are very vocal. Hippos return to water in the early morning to escape all disturbances that might affect them.
Location; -Queen Elizabeth N.P
-Murchison Falls N.P
– L. Mburo N.P
- ii) Bush pig; a bush pig weighs between 45-150kg. It is compact, with slab-like, short legged body, tapping into the head and snout with little indication of a neck. The dorsal crest and face are often white or grey. Body color varies from blonde or red to grey, brown or black. A wide range of forested and woodland habitats, with a distinct preference for valley bottoms with dense vegetation and soft soils are mostly preferred by bush pigs.
A bush pig is an omnivorous animal. Roots, tubers, bulbs and corns are the basic foods. Fallen fruits, herbage and reptiles supplement its diet. It occasionally scavenges. A female and her young are often accompanied by an adult male within a restricted area where trunk-slashing along paths and rubbing posts suggest that males perhaps females too are terrestrial. Large associations are seen but only rarely. Home ranges of up to 10km sq. have been estimated and nightly foraging walks of up to 6 km.
Location; most parks of Uganda
- ii) Common Warthog; A female animal weighs between 45-75kg while a male one is between60-150kg. This animal is relatively long-legged but short necked with prominent, curved tusks. The facial callosities or ‘warts’ consist of 3 paired masses of thickened skin and connective issue protecting the jaws, eyes and the muzzle. Warthogs run at a high, jaunty trot, with back straight and the very narrow tail held vertically. The head is held high .Feeding animals drop to their knees and commonly graze in this position, with their hind quarters raised.
Warthogs are common in alluvial soils in lightly wooded country with a mosaic of vegetation types but well distributed throughout savannah and open woodland areas. They graze throughout the rains searching mats of short species. They strip growing grasses of their seed heads. During dry season, they turn to leaf bases and rhizomes that store nutrients using their sharp edge of the nose disc. Mothers and their female offspring retain the most enduring bonds. Thus a new family unit joins others that are probably also close relatives. These loose groupings live within clan areas averaging about 4km sq.
- iv) Giraffe; a giraffe is between 450-180kg for a female while a male one is between 1800-1930kg. The length of a giraffe’ neck is only matched by that of its legs and its low motion lope covers ground at a great rate. Giraffes can run at 60km/h. Both young and old are able to outstrip most predators. The neck is fringed with a short, thick mane and both sexes develop three horns above the eyes. The face is strongly tapered and a 45cm tongue is the principle means of gathering foliage into the large, elastic mouth and lips. They prefer savannahs, open woodlands and seasonal flood plains with abundant termitary thickets. They are common in areas where rainfall, soils wind or flooding favor scattered low and medium woody growth.
The giraffes like feeding on abundant green deciduous growth during which time they are widely dispersed. They select nutritious foliage that makes modest feeding possible. Adult males are vestigially territorial because the mature bulls monopolize all mating and are intolerant of other large males. Females have unstable home ranges that keep on drifting from year to year except during periods of motherhood. New born calves rise to their feet within 5 minutes and after a week or so may join other calves in the vicinity. Mothers tend to leave their crèche of youngsters on their own and that is why between half and three-quarters of all giraffes fail to survive due to predation
Location; – Kidepo Valley N.P
- v) Buffalo; this animal is between 250-850kg in weight. It is a large ox with thick, bossed horns and tasseled ears. The coat is short, often sparse and colored from a rich red to black. The underside and chin of the buffalo is often pale and patches of contrasting color appear on the face and legs. Buffalos are most common in the forests with water courses and water-logged basins. They prefer humid climate that favors continuous plant growth. Savannahs and mosaics endowed with patches of thicket and reeds provide favorable habitats for buffalos. They feed on a wide range of grasses including swamp vegetation. Grazing is influenced by disturbance or human predation with animals switching from continuous grazing to dawn, dusk and night time grazing.
They form small groups of up to 12 animals with related females and their offspring as the core and 1 or more attendant males. Other males are solitary or form small bachelor parties. Buffaloes can form a large gathering of as many as 200 animals only possible during the rains or on major patches of rich pasture. Gestation lasts about 11 months and birth intervals of 2 years are normal. The cow-calf bond is very strong and exclusive but the female attachment to her herd is also close.
Location; – Queen Elizabeth N.P
– Murchison Falls N.P
– Kidepo Valley N.P
- vi) Bush buck; a female bush buck weighs between 24-60kg while a male one is between 30-80kg. It is a small bovine. Females and young are mainly red and males become progressively black with sexual maturity and age. The undersides are white; there are white flashes above black hooves and white markings on face and ears. Bush bucks are dependent on thick cover for protection. They can subsist on dew and sometimes lives in reed beds.
They largely depend on scrubs, leguminous herbs and growing grass. Also pods, fruits of many species form an important part of their diet. Their feeding habits are largely influenced by disturbances and predators. Bush bucks rest and ruminate frequently. They live at variable densities, not territorial but solitary when feeding.
Location; – most parks of Uganda.
vii) Sitatunga; a female animal weighs between 40-85kg while a male one weighs between 80-130kg. Sitatungas are shaggy-long legged bovines, distinguished by spread-eagled stance and long splayed hooves. Females are larger and darker with heavy, sharply keeled horns. They feed on scrubs, herbs and grasses with strong regional biases. Sitatungas are most active from18:00-10:00 at night.
A rich, year-round supply of greenery, permits sitatungas to form small home ranges and potentially high densities. Females are especially prone to gather in high density areas and may be accompanied by more than one generation of calves. They have a clumsy gait but are quiet and deliberate in their movements.
viii) Dwarf antelope; this mammal is 5.5kg in weight. The male antelope is heavier than the female. It has a soft mahogany-brown fur which has a shiny gloss. White markings are conspicuous. The smaller male has very short conical horns. It prefers dense, low undergrowth near water courses, roads, gardens and Chablis as its habitat. It feeds on shoots and browses leaves.
Location; Queen Elizabeth N.P
- ix) Water buck; A female animal is between 160-200kg while a male is between 200-300kg. It is variable in color where grey and rufous individuals are in mixed groups. A male has long horns, rump crescent and is white under tail. It is sedentary in savannahs, woodland and mosaics close to permanent water. Water bucks feed on many species including reeds and rushes. Both sexes remain for up to 8 years on same home range.
Location; – most parks of Uganda
- x) Uganda Kob; a female kob weighs between 60-70kg whereas a male one is between 85-121kg. Males have thick, lyrate horns; coloring varies from rufous or pale brown to black and white in the suds flood plain. They prefer flats or gently rolling country close to water as their habitat.
Uganda kobs graze on the commonest grasses. Their behavior is characterized by resident populations which move daily between habitual grazing grounds and watering places.
Location; most parks of Uganda.
- xi) Oribi; a male oribi is between 12-22kg while a female one averages 2kg heavier. It is a tall, slender and has sandy body color with white undersides, upper throat, and mouth and ear linings. Its light colored muzzle deflects down sharply from the fore head. An oribi is shy and alert, utters piercing whistle as it flees with rocking-horse gait.
It mainly depends on fresh green grass as its food. Females are larger than males and independent in their movements but as the object of the continuous attention from a single male, each adult female determines the area within which he is intolerant of other males. Whistle may serve as both alarm and also to advertise shifting positions and movement.
xii) Impala; a female impala weighs between 40-60kg while a male one is between 45-80kg. Impalas are gazelle-like with brown or yellowish brown back, lighter on haunches, shoulder, neck and head and sharply lighter on flanks. Underside, chin, mouth and ear linings are white. Ear tips, thigh stripes, mid line of tail and bushy fetlock glands are black. Adult males have long narrow horns, with shallow, well spaced annulations, that arch up and out then back and up. The most preferred habitats for impalas are edges between grasslands and denser woodlands. They occupy grasslands during rainy seasons while woodlands are occupied during the dry seasons.
Impalas almost are wholly grazers during the rains. When grass decreases, they resort to woodlands, browsing on scrubs, herbs, pods and seeds. Feeding occurs mainly in two major bouts i.e. around dawn and dusk and two minor bouts i.e. night and early afternoon with shading and ruminating in between. Females form clans of 30-120 animas with home ranges radiating out from fairly stable centers. Although gregarious, neither females nor males form lasting associations. Most healthy adult males are intolerant in presence of oestrus females, so fights are very common during the rut.
Location; – Queen Elizabeth N.P
– Murchison Falls N.P
– L. Mburo N.P
xiii) Eland; a female eland weighs between 300-600kg while a male one is between 400-942kg.The animals are very large, tan bovine in which both sexes have horns and dew lap. They have long tail with tufted tip and narrow, relatively small ears. Males tend to increase in weight throughout their life, neck and shoulders darken from tan to grey and dew lap enlarges until it hangs below the level of the knees. Hair on males’ fore head also changes, becoming more and bushier. Mouth and muzzle are small and pointed in comparison to those of buffaloes and cattle.
Elands are primarily animals of the woodlands and woodland savannah. They gather in large herds during and after the rains and scatter into smaller groups in the dry season. They browse foliage and herbs. In dry seasons, elands feed on myrrh and bush willows. Malula fruit and acacia seeds are eaten in large quantities in the dry season.
Mutual attraction among calves leads to temporally isolated groups of up to 50 animals from where female herds form hierarchies determined by principle of rank, age and size in both sexes. They temporarily congregate up to 100 where young female animals are known to be nomadic while older male animals are more residential. More mating take place during rains from which birth is given after 9months at the end of dry season. Elands can live up to 25 years.
Location; – L.Mburo N.P
– Queen Elizabeth N.P
xiv) Duikers; these are forested antelopes with compact body, head and short wedged head with horns. There are several sub-species but we shall look at a bush duiker as a case study.
Bush duiker is long-legged and has larger ears than forest duikers. Their color varies according to the region it is placed in. Male animals are the only ones with straight, upright horns. It flourishes in a wide range of habitats.
Leaves and shoots of numerous dominant bush plants, fruits are very important in their diet. The bush duiker does not need water Male animals defend territories with little or no overlap in range.
Location; – L. Mburo N.P
– Queen Elizabeth N.P
- xv) Topi; a female topi weighs beyween75-150kg while a male one is between120-160kg. They are large, compact antelope with deep chest, prominently ridge shoulders, rather short neck and long face. The tail is narrow and fringed. Horns vary from one region to another but all have backward curving stems and forward or inward curving tips. Their body color varies from rather yellowish bleached brown to red or even purplish brown. Black patches on hind quarters and fore legs above, are ochre- colored stockings. Topis prefer seasonally flooded grasslands. They follow receding waters in the dry season and retreat into higher ground in the rains or flood season. These animals like naturally short or medium height pastures.
Although most valley grasses are taken are taken, they prefer very short leaves which are striped from the stems with a nodding action that finely balances raking wrenches with clipping bites. Despite the topis living in large migratory herds, they may co-exist with other residential animals. Residents probably off shoots of larger aggregations but they occupy territories defended by males. Large groups have very intense rutting while herds are at their most concentrated. Young are born after an 8 month gestation. The sandy-fawn calf lies up for a few days before joining its mother. Young often gather spontaneously and females may form a defensive ring around them. |
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Teacher Resources by Grade
|1st - 2nd||3rd - 4th|
|5th - 6th||7th - 8th|
|9th - 10th||11th - 12th|
Defining Literacy in a Digital World
|Grades||9 – 12|
|Lesson Plan Type||Standard Lesson|
|Estimated Time||Three 50-minute sessions|
While students interact with a range of print, visual, and sound texts, they do not always recognize that these many documents are texts. By creating an inventory of personal texts, students begin to consciously recognize the many literacy demands in contemporary society. Students begin by brainstorming a list of items that combine different ways of expressing ideas—such as a poster or DVD. After the lists are shared, list items are identified as texts (audio texts, video texts, etc.) Students then create an inventory of significant texts that they have engaged with over a specified period of time, and discuss why it is important to interact with a variety of different types of texts. With this start, they create a working definition of literacy that they refine and explore as they continue their investigation of the texts that they interact with at home, at school, and in other settings.
The literacy demands that students face today have changed greatly from those which students met even five or ten years ago. NCTE’s Topical Resource Kit, Professional Communities at Work: Engaging Media-Savvy Students: Exploring Multimodal Literacies through Popular Culture and Technology explains:
Classrooms are rapidly moving beyond traditional notions of text. For years, teachers relied almost completely on books and other print texts—especially in terms of the texts that students were asked to compose. Because of the changes in technologies available to us today however, texts in the classroom frequently include a much wider range of modalities—systems that people use to make meaning. In fact, a single text often engages more than one way of making meaning.
Today’s media-savvy students compose and read texts that include alphabetic- and character-based print, still images, video, and sound. They listen to podcasts, watch animations on the Internet, film their own videos, and compose visual arguments on paper and online. Reading and composing for these students includes such features as visual design, nonlinear organizational structures, and oral storytelling techniques. (“Framing Text” 3)
Students interact with this wide range of texts using ever-expanding strategies for making meaning; yet they do not always recognize these many resources as legitimate texts. By exploring the ways that they read and write in this lesson, students extend their understanding of what it means to be literate in the digital age.
National Council of Teachers of English. 2005. Professional Communities at Work: Engaging Media-Savvy Students: Exploring Multimodal Literacies through Popular Culture and Technology. Topical Resource Kit. Urbana, IL: NCTE. |
What is bronchiolitis?
Bronchiolitis is a common chest infection in young children. It usually causes a flu like illness that affects infants in the first year of life. It is caused by several different viruses. Bronchiolitis occurs frequently in the winter months and rarely in summer.
The virus infects the small breathing tubes (bronchioles) of the lungs. This causes them to become narrowed by mucus and inflammation.
How does the illness develop?
The illness begins as a cold. After a day or so, your baby begins to cough, and the breathing becomes fast and sounds noisy (wheezy). This fast, wheezy breathing can make it difficult for your baby to feed. Some children may need to be admitted to hospital because of these problems.
The first symptoms your baby may have are the same as a common cold. These symptoms last one to two days and include:
- a runny nose
- a mild cough
They are followed by an increase in problems related to breathing, such as:
- fast breathing
- poor feeding
- noisy breathing (wheezing)
- drawing in of the chest with each breath
What can I expect once my baby becomes ill?
Babies with bronchiolitis are usually worse on the second or third day and are often sick for 7 to 10 days. The cough may continue for up to 2 to 4 weeks.
Are tests needed to diagnose bronchiolitis?
A chest X-ray is not recommended as it has been proven that it does not help with the management in infants presenting with bronchiolitis. Blood tests are generally not helpful.
Are there any medications that may help?
Medicines do not usually help babies with bronchiolitis.
- Antibiotics are not given because bronchiolitis is caused by a virus and antibiotics do not cure viruses.
- VentolinTM, AtroventTM or other puffers are not prescribed as these have been proven not to help as the wheezing is not related to asthma.
- Steroids such as PredmixTM or cortisone based medicines also do not help.
What else can I do for my baby?
Babies need to rest and have small frequent feeds so they don't get too tired when feeding and do not get dehydrated.
Most babies with bronchiolitis can be managed at home.
- Do not smoke in the home or around your baby. This is especially important around babies with any breathing problems.
- Encourage your baby to rest.
- Give shorter breast feeds/formula/water more frequently. This way your baby does not get too tired when feeding. If your child does not get enough fluids they can get dehydrated.
- You can give Paracetamol (eg. PanadolTM, DymadonTM, PanamaxTM) if your baby has a temperature and is unsettled.
- Avoid contact with other babies in the first few days, as bronchiolitis is an infectious disease.
- Hand washing helps with the prevention of spread of the virus.
If your baby is distressed and having trouble feeding they may need to be admitted to hospital.
Staff may need to:
- Watch them closely to make sure they do not become more unwell.
- Give them some extra oxygen.
- Give them extra fluids through a tube placed through the nose into the stomach or a drip into a vein.
Will it happen again?
Maybe. It is possible to have bronchiolitis again, but most babies will only have it once.
Children exposed to second hand smoke are more likely to develop a range of illnesses including bronchiolitis, compared to children living in smoke-free environments.
If you do smoke, you can choose not to smoke in front of children, particularly in enclosed areas such as the car and home. Ask others to do the same.
When to see your doctor
Go to your nearest doctor or emergency department if your baby:
- has difficulty breathing (very fast or not regular breaths).
- cannot feed normally because of coughing or wheezing.
- turns blue or has skin that is pale and sweaty.
Make an appointment for your baby to see a doctor if:
- they have a cough that is getting worse.
- they have less than half their normal feeds or are refusing food or drinks.
- they seem very tired or are more sleepy than usual.
- you are worried in any way.
- Babies need to rest and drink small amounts more often or have more frequent breast feeds.
- Bronchiolitis is an infectious disease in the first few days.
- It is more common in babies under 6 months.
- Babies usually get better in 7 to 10 days but the cough may continue for up to 2 to 4 weeks.
- It is a viral infection, so antibiotics will not help.
- Smoking in the home increases the chance of babies having bronchiolitis and will make it worse.
- See your doctor if your baby has difficulty with breathing, feeding or sleeping.
Republished in part with permission from Paediatric Research in Emergency Departments International Collaborative (PREDICT), 15/08/2017. |
Yellow summer squash (Cucurbita pepo), is a group of summer squash that produces long, thin yellow fruits that can either have a straight or crookneck and warty or smooth skin. Technically the same species as zucchini, these annual garden plants require regular water to encourage establishment, vigorous growth and the production if high-quality fruits. Properly timing watering and applying the water is often just as important as using an appropriate quantity of water.
Yellow summer squash, as a general rule, requires 1 inch of water weekly through rainfall or supplemental watering. During hot, dry weather or periods of vigorous growth, the yellow squash benefits from up to 2 inches of water weekly. Maintaining a 2- to 3-inch layer of an organic mulch around the squash conserves soil moisture and reduces how often you need to water.
How to Water
Typically, if the soil 1 inch below the soil surface feels completely dry to the touch, the yellow squash needs watering. Each watering session should moisten the top 6 inches of soil. Water the squash in the early morning so the plant's leaves will not remain wet at night. Drip irrigation or directly watering the soil around the squash plant will avoid disease-spreading splashing and reduce runoff and evaporation.
- Photos.com/PhotoObjects.net/Getty Images |
Year 2013, like 2007, was the sixth warmest on record and continued the long-term global warming trend, said the World Meteorological Organization (WMO). The international body, which issued its annual statement on the Status of the Climate on World Meteorological Day (March 23), highlighted the key climate events of 2013.
Thirteen of the 14 warmest years on record have all occurred in the 21st century, and each of the last three decades has been warmer than the previous one, culminating in 2001-2010, which was the warmest decade on record. The average global land and ocean surface temperature in 2013 was 14.5°C (58.1°F) – 0.50°C (0.90°F) above the 1961–1990 average and 0.03°C (0.05°F) higher than the 2001–2010 decadal average. Temperatures in many parts of the southern hemisphere were especially warm, with Australia having its hottest year on record and Argentina its second hottest.
Australia’s recent heat waves gain focus
The Status of the Climate Report contains a peer-reviewed case study of Australia’s record warmth in 2013. The study by scientists at the ARC Centre of Excellence for Climate System Science University of Melbourne, Australia, used nine state-of-the-art global climate models to investigate whether changes in the probability of extreme Australian summer temperatures were due to human influences. The report provides a snapshot of regional and national temperatures and extreme events as well as details of ice cover, ocean warming, sea level rise and greenhouse gas concentrations—all inter-related and consistent indicators of our changing climate.
Naturally occurring phenomena such as volcanic eruptions or El Niño and La Niña events have always contributed to framing our climate, influenced temperatures or caused disasters like droughts and floods. But many of the extreme events of 2013 were consistent with what we would expect as a result of human-induced climate change, said WMO secretary-general, Michel Jarraud.
Heavier precipitation, more intense heat, and more damage from storm surges and coastal flooding as a result of sea level rise—as typhoon Haiyan so tragically demonstrated in the Philippines—were some of the examples, said Jarraud.
“There is no standstill in global warming,” said Jarraud. The warming of our oceans has accelerated, and at lower depths. More than 90 per cent of the excess energy trapped by greenhouse gases is stored in the oceans. Levels of these greenhouse gases are at record levels, meaning that our atmosphere and oceans will continue to warm for centuries to come. The laws of physics are non-negotiable.”
Comparing climate model simulations with and without human factors shows that the record hot Australian summer of 2012/13 was about five times as likely a result of human-induced influence on climate and that the record hot calendar year of 2013 would have been virtually impossible without human contributions of heat-trapping gases, illustrating that some extreme events are becoming much more likely due to climate change, the study concluded.
WMO’s statement, which is an internationally recognised authoritative source of information, has highlighted following key climate events of 2013:
- Typhoon Haiyan (Yolanda), one of the strongest storms to ever make landfall, devastated parts of the central Philippines and claimed almost 10,000 lives
- Surface air temperatures over land in the Southern Hemisphere were very warm, with widespread heat waves; Australia saw record warmth in the year, and Argentina its second warmest year and New Zealand its third warmest
- Frigid polar air plunged into parts of Europe and the southeast United States
- Angola, Botswana and Namibia were gripped by severe drought
- Heavy monsoon rains led to severe floods on the India-Nepal border
- Heavy rains and floods impacted northeast China and the eastern Russian Federation
- Heavy rains and floods affected Sudan and Somalia
- Major drought affected southern China
- Northeastern Brazil experienced its worst drought in the past 50 years.
- The widest tornado ever observed struck El Reno, Oklahoma in the United States
- Extreme precipitation led to severe floods in Europe’s Alpine region and in Austria, Czech Republic, Germany, Poland, and Switzerland
- Israel, Jordan, and Syria were struck by unprecedented snowfall
- Greenhouse gas concentrations in the atmosphere reached record highs
- The global oceans reached new record high sea levels
- The Antarctic sea ice extent reached a record daily maximum.
The global temperature assessment is based on three independent datasets that are maintained by the Met Office Hadley Centre and the Climatic Research Unit of the University of East Anglia (HadCRU), both in the United Kingdom; the National Climatic Data Center of the National Oceanic and Atmospheric Administration (NCDC NOAA), based in the United States; and the Goddard Institute for Space Studies (GISS) operated by the National Aeronautics and Space Administration (NASA), also in the United States. |
Cognitive Therapy for Children & Teens
With the right training, a child’s brain can be taught to overcome any learning challenge. At Learning Enhancement Centers, we use a variety of programs to help students become independent learners.
Processing And Cognitive Enhancement (PACE) is a structured program with sequential activities. Unlike other learning disability programs that focus on behavior management or specific academic skills, PACE improves the brain’s processing ability.
The Listening Program uses music and sound stimulation to re-educate the auditory pathways in order to increased attention, listening, sensory integration, communication, and physical coordination.
Attention Focus Training uses a combination of balance, movement, and reflex integration activities to increase the ability to attend to tasks. Students are taught to take an active role in learning by recognizing when they lose focus and consciously regaining control.
The LEC Reading Program, developed by our staff and modeled after the process by which spoken language is first learned, addresses the five elements of reading skill: phonemic awareness, phonics, vocabulary, comprehension, and fluency.
Easing Into Reading helps in the development of sound-to-letter matching, an essential part of phonetic reading development, with a variety of tasks that emphasize the consistent verbalizing of sounds from visual symbols and the written recording of letters from dictated sounds.
Reading and Reasoning, developed by our staff, helps students develop an “inner voice” that directs them in monitoring comprehension.
Visualizing and Verbalizing teaches students to visualize what they read and verbalize what they imagine—thereby helping them to connect with the material they’re reading.
Discover Math, developed by the Reading Foundation, is a multi-sensory approach to learning math. Mental imagery and language are combined to provide an understanding of mathematical concepts. |
A man went to Monte Carlo to try and make his fortune. Is his strategy a winning one?
Two bags contain different numbers of red and blue marbles. A marble is removed from one of the bags. The marble is blue. What is the probability that it was removed from bag A?
You and I play a game involving successive throws of a fair coin.
Suppose I pick HH and you pick TH. The coin is thrown repeatedly
until we see either two heads in a row (I win) or a tail followed
by a head (you win). What is the probability that you win?
Practical work seems particularly important for this
Start with estimating 10 cm. Give the group a minute or two to
practise with a ruler, then with all measures or samples out of
sight ask them to put two marks on a fresh piece of paper. The data
are collected, to the nearest mm. Before examining the
data invite students to make a guessed description of the data set.
Is it symmetric ? What is it centred on? How dispersed?
Next take five dice and run 20 trials counting the number of
sixes each time. Ask students to plot that frequency
If possible have each member of the group with a shuffled pack
of cards. Conduct the synchronised card turning and collect the
number of Aces of Spades observed at each card turn. If the group
is small perhaps report every ace, and later ask what effect this
change in the rules had on the distribution. Similarly any royal
card might also be included in the set of cards reported. As before
ask the group how this affects the distribution.
Now work with tossed coins. Five, as with the dice, and also one
coin for every member of the group. This should help students see
how the dice and cards activities are structurally the same. They
differ from the coin tossing in their asymmetry and it can be seen
how both the chance of a sighting (six or ace) and the sample size
(five dice or hundred packs of cards) affect the
Although the vocabulary 'discrete' and 'continuous' may help
distinguish these two from the distribution of 10cm estimates,
acquisition of correct technical terms is not the most important
There is plenty to discuss about the 10cm estimates: Is this
variable random? Is it symmetric? Does this data sample match
One key point to include within the discussion is that once we
collect the data to the nearest mm it becomes discrete but the
variable itself was continuous (there are no two distinct values
which cannot have another value between them)
How do we compare two sets of data, say for height statistics
for 11 year olds now and fifty years ago? Why can't we do exactly
the same with probability and sample data?
When five dice are rolled what is the probability that we see no
sixes, or one six only, or two sixes, three, four, or five? What
will the probability values for each of these come to as a
When a person estimates 10cm do you think there is probably more
chance of their estimate being within one centimetre of 10cm than
of being off by between 5cm and 6cm? Do you think estimating too
much is as likely as too little? Why?
How is Aces High like Five Dice? How is it different? And what
if this involved tossing a coin rather than dice and cards?
10cm is different to Five Dice in some key ways - what would you
say those differences were? |
Writing in the "Perspectives" section of the June 9 issue of SCIENCE, William E. Bradshaw, professor of biology, and Christina Holzapfel, biology research associate, show that diverse animal populations have changed genetically in response to rapid climate change. These genetic changes are in response to altered seasonal events and not to the expected direct effects of increased summer temperatures.
Global warming is proceeding fastest at the most northern latitudes, resulting in longer growing seasons while simultaneously alleviating winter cold stress without imposing summer heat stress. In short, northern climates are becoming more like those in the south.
"Over the past 40 years, animal species have been extending their range toward the poles and populations have been migrating, developing or reproducing earlier," said Bradshaw. "These expansions and changes have often been attributed to 'phenotypic plasticity,' or the ability of individuals to modify their behavior, morphology or physiology in response to altered environmental conditions."
However, adds Holzapfel, "phenotypic plasticity is not the whole story. Studies show that over the past several decades, rapid climate change has led to heritable, genetic changes in animal populations."
Bradshaw and Holzapfel provide a number of examples of these changes: Canadian red squirrels reproducing earlier in the year; German blackcaps (birds) are migrating and arriving earlier to their nesting grounds; and, North American mosquitoes living in the water-filled leaves of carnivorous plants are using shorter, more "southern" day lengths to cue the initiation of larval dormancy.
In contrast, the authors write that no studies have found genetic changes in populatio
Source:University of Oregon |
Close Reading Packs Tips
Engaging Passages Teach 21st Century Skills
Build important 21st century skills, such as critical thinking, collaboration, and communication, with our Close Reading Packs. Focusing on a Key Question, each student in a group reads a short fiction or nonfiction passage on a shared topic. Small-group and whole-class discussions help students begin to answer the Key Question. Finally, all students read a Connecting Passage meant to guide them when applying their close reading and communication skills.
Why Use Close Reading Packs
Close reading requires student to analyze, evaluate, and think critically about a given text. By combining those skills with collaboration and communication skills to construct an answer to a text-dependent Key Question, Close Reading packs provide teachers with a powerful tool to meet rigorous standards.
How to Use Close Reading Packs
The Teaching Tips that accompany each Close Reading Pack provide suggestions to help teachers act as discussion leaders as well as address important skills such as comprehension, author's craft, and critical thinking.
- Four Student Passages allow for close reading practice on cross-curricular topics in individual and group work settings.
- The Connecting Passage lets students apply their learning.
Student Response Sheet
- This two-page form lets students record evidence needed to answer the text-dependent Key Question.
- This document provides suggestions to help you act as a discussion leader as well as address important skills such as comprehension, author's craft, and critical thinking.
- The tips also set a purpose for note-taking and re-reading skills and strategies that help students answer Key Questions and meet Common Core State Standards.
Science InvestigationsHelp students dig deeper into science content with Investigation Packs from Science A–Z. Students practice close reading and working in groups while answering text-dependent questions. |
What Is It?
Strokes can damage brain tissue in the outer part of the brain (the cortex) or deeper structures in the brain underneath the cortex. A stroke in a deep area of the brain (for example, a stroke in the thalamus, the basal ganglia or pons) is called a lacunar stroke. These deeper structures receive their blood flow through a unique set of arteries. Because of the characteristics of these arteries, lacunar strokes happen a little bit differently from other strokes.
A lacunar stroke occurs when one of the arteries that provide blood to the brain's deep structures is blocked. These arteries are small, and are uniquely vulnerable. Unlike most arteries, which gradually taper to a smaller size, the arteries of a lacunar stroke branch directly off a large, high-pressure, heavily muscled main artery. High blood pressure (hypertension) can lead to lacunar strokes because it causes a pounding pulse. Since the arteries don't gradually taper down in their size, high blood pressure can directly damage these arteries. High blood pressure also can cause atherosclerosis, a condition in which fatty deposits (plaques) build up along the walls of blood vessels. When atherosclerosis is present, a clot can form inside of one of these small arteries, blocking blood flow in the artery.
Unlike strokes that damage the cortex, lacunar strokes are only rarely caused by a blood clot (also called a "thrombus") that forms elsewhere in the body, such as the neck or heart, and travels through the bloodstream to the brain. After a clot (or any debris) begins to travel through the bloodstream it is called an embolus. It is difficult for an embolus to make its way into the small arteries that can cause a lacunar stroke.
Many of the deep brain organs that can be injured by a lacunar stroke help to relay communication between the brainstem and the brain cortex, or help to coordinate complicated body movements. In a lacunar stroke, brain cells in a relatively small area (measuring from 3 millimeters to as much as 2 centimeters across) are damaged or killed by lack of oxygen. Such a small area of brain destruction is called a lacune. A lacunar stroke involves only a small area of the brain, but it can cause significant disability.
Lacunar strokes account for about 20 percent of all strokes in the United States.
The symptoms of lacunar stroke vary depending on the part of the brain that is deprived of its blood supply. Different areas of the brain are responsible for different functions, such as sensation, movement, sight, speech, balance and coordination.
Symptoms can include:
Weakness or paralysis of the face, arm, leg, foot or toes
Clumsiness of a hand or arm
Weakness or paralysis of eye muscles
Other neurological symptoms
In a person with prolonged, untreated high blood pressure, multiple lacunar strokes can occur. This can cause additional symptoms to develop, including emotional behavior and dementia.
The sudden appearance of one or more of these symptoms is a warning sign that a stroke may be in progress. Sometimes, the small clots that can cause a lacunar stroke interfere with blood flow only for a few minutes. If the clot dissolves before damage is done, then symptoms can begin to improve within minutes and may go away completely. When symptoms go away without treatment and full recovery occurs within 24 hours, the event is called a transient ischemic attack (TIA). Never decide to wait and see whether stroke symptoms will go away on their own. Get to an emergency room as quickly as possible to get treatment.
Your doctor will ask about your medical history (high blood pressure, heart disease, smoking, high cholesterol and diabetes). He or she will check your vital signs (temperature, pulse, breathing rate and blood pressure) and might order an electrocardiogram (EKG).
Lacunar strokes usually are identified by a computed tomography (CT) scan or magnetic resonance imaging (MRI) scan of your brain. An MRI technique known as diffusion weighted imaging is particularly sensitive for identifying very new lacunar strokes.
If your symptoms continue without improvement during the time you are traveling to an emergency center, it is best to assume that your event is a full-blown stroke, not a TIA. If a lacunar stroke is treated early, full recovery is possible. If medicines restore circulation to the brain quickly, symptoms of a lacunar stroke may go away within hours. If blood supply is interrupted for a longer time, brain injury may be more severe, and symptoms may last for many weeks or months, requiring physical rehabilitation. There may be permanent disability.
You can help to prevent lacunar stroke by preventing or controlling the risk factors for stroke – high blood pressure, smoking, heart disease and diabetes. If you have high blood pressure or heart disease, follow your doctor's recommendations for modifying your diet and taking your medication. Exercise regularly, eat plenty of fruits and vegetables, and avoid foods filled with saturated fats and cholesterol. If you smoke, quit. If you have diabetes, monitor your blood sugar level frequently, follow your diet, and take your insulin or oral diabetes medication as your doctor has prescribed.
If you have had a lacunar stroke, your doctor may recommend a daily aspirin or other blood-thinning medication, such as ticlopidine (Ticlid) or clopidogrel (Plavix). These medicines may reduce your risk, but their benefit has been more obvious for stroke types other than lacunar strokes. If you have never had a stroke of any kind, you might lower your risk for a first stroke if you take a daily aspirin. There is strong evidence that stroke risk is reduced for women over the age of 45 who take aspirin once every other day. This benefit has not been proven for men.
If doctors are able to provide treatment within three hours after symptoms start, they probably will use with a clot-dissolving medication. Although the blood-thinning medication heparin often is used to treat strokes that affect large arteries, it does not appear to help people with lacunar strokes recover.
A person who has had a lacunar stroke usually is hospitalized so that he or she can be observed in case symptoms worsen. A person with a severe stroke may need help with self-care or feeding. In the hospital, an occupational therapist and a physical therapist can help the person to work around a new disability and to regain strength after brain injury. Commonly, hospitalization is followed by a period of residence at a rehabilitation center, where additional intensive therapy may be given. The goal of rehabilitation is to maximize recovery. To prevent future strokes, it is very important for you to control high blood pressure. It helps to take a daily aspirin or other blood-thinning medication (ticlopidine or clopidogrel).
When To Call a Professional
Call for emergency treatment immediately whenever the symptoms of lacunar stroke occur, even if these symptoms last only a few minutes. For best results, stroke treatment must occur within three hours of the start of symptoms.
People often begin to recover within hours or days of a lacunar stroke. Lacunar strokes have a better rate of recovery than other strokes that involve larger blood vessels. More than 90 percent of people with a lacunar stroke will recover substantially within the first three months following the stroke.
Learn more about Lacunar Stroke
Symptoms and treatment for:
National Institute of Neurological Disorders and Stroke
P.O. Box 5801
Bethesda, MD 20824
National Stroke Association
9707 E. Easter Lane
Englewood, CO 80112 |
The connected machine is a single function that takes an input, runs it through the network inside and produces an output. You control a network of function machines along with the input and the operation performed by each machine to solve problems.
As the pollster for candidate Higgins, you need to know how she is faring with different groups. Read her political profile, view the demographic profile of the city, decide on the groups to poll, review the results and learn about random sampling.
It’s make or break time at the end of the campaign so you must read Ms. Higgins’ political profile, view the demographic profile of the city and decide how many people to poll out of the entire voting age population of 16,000 to get accurate results.
This timeline provides insight into the long history of struggle of the black population of South Africa. Follow the centuries of European wars and colonial rule and the policies that led to apartheid.
Test your detective skills when you read three random documents. You will have three minutes to read each document, answer two questions about the region, two questions about the time period and three questions about the document.
Contestants in grades 1-8 will listen to three stories, one at a time, and then spell words from each story. Students in high school will listen to separate sentences and then spell the words from each sentence.
When the light of a star passes through a spectrograph, elements of that star reveal a specific signature. Compare the spectra of four elements and a star to identify which elements you can detect in the star's atmospere.
To find the area of a shape, surround the shape with a rectangle, determine the areas of the rectangle and subtract the pieces of the rectangle that are outside the original shape. Use this geoboard to create shapes and determine their areas. |
A slab of banded iron at the National Museum of Natural History in Washington, D.C.
From the placard:
Banded iron formations consist of alternating iron-rich and iron-poor bands. In this polished specimen from the Lake Superior region, the gray, metallic bands are nearly pure iron oxide (hematite). The red bands are jasper — silica chert colored by minute amounts of iron oxide.
These iron formations are found throughout the world in Precambrian deposits, but are rare in younger rocks. They are thought to represent a transitional stage in the development of our present oxygen-rich atmosphere. During the time when banded iron formations were deposited, vast amounts of iron dissolved in the oceans probably “soaked up” free oxygen by combining with it to form oxides. This “rust” then settled quietly to the bottom to create the iron deposits. Only when the supply of unoxidized iron was finally exhausted, which must have taken many hundreds of millions of years, did the amount of free oxygen begin to increase toward modern levels.
The characteristic banding is an enigma. It may correspond to “boom” and “bust” periods of oxygen-producing organisms, or, as others have suggested, to periodic upwellings of iron-rich water from deeper basins. |
This is a two-day lesson that compares two women in the Revolutionary war era. Instead of focusing on individuals who fought in the Revolutionary war, this lesson focuses on people that were important and made an impact in the Revolutionary era. The first day, will focus on Phillis Wheatley. The second day will focus on Mercy Otis Warren. This lesson plan only includes day one. This lesson can also be integrated with Reading since students will be reading a play about Phillis Wheatley and finding the theme of the play in a future reading lesson.
Students will be able to analyze views, lives, and contributions of Phillis Wheatley of the Revolutionary period by examining primary resources related to her and completing an exit card stating why she was important.
- Image of Phillis Wheatley (white out information around the image for close reading; show original image after discussion)
- Guiding Questions
- Short biography of Phillis Wheatley
- Poem Book Images: An Elegiac Poem & Cover of Poem Book
- Poem, “From Africa to America”
- Letter to Occum
- Note: All materials were printed from the web resources. The biography, original book images, letter to Occum, and poem “From Africa to America,” were stapled into a packet.
- Group students into groups of 4 or 5 students
- Hand out an image of Phillis Wheatley along with the guiding questions. You will have to white out the information around the photograph. Students will have about 8 minutes to analyze and do a close reading of the image of Phyllis Wheatley and answer the guiding questions. With remaining time, students can write their own questions and discuss them.
- Discuss the responses with the students.
- Show students the same Phillis Wheatley image with the words uncovered. Continue to discuss this “new” information and how it confirms or refutes their close reading.
- Hand out Phillis Wheatley packet. The first page is a biography. Read the biography aloud with the students. Discuss this information further and connect it to the image.
- Have students view more primary sources. They will be looking at poems from Phyllis’ book.
- Have students look at Phillis’ “Letter to Occum.” Have them do a close reading of the document. Provide assistance with difficult vocabulary words. Connect this letter about anti-slavery to what injustices are happening in Boston at this time.
- Analyze Phillis’ poem, “From Africa to America.” Have students connect how this poem relates to her life.
- Summative discussion (reflection): Review the point of the lesson. “What were some of Phillis’ accomplishments? Why is she an important person in history?”
- Have the students complete the exit card on a note card and turn it in.
- Reading integration: unit 3, plays: Early finishers will read a play about Phillis Wheatley. This play will be used in a future reading lesson about finding the theme in a play.
Exit card question (on notecard)- Why is Phillis Wheatley an important figure in history? Use evidence from today’s lesson in your response.
“People and Events: Phillis Wheatley.” PBS: Africans in America. http://www.pbs.org/wgbh/aia/part2/2p12.html (accessed August 28, 2011).
Marin, Lucian. “A Poem by Phillis Wheatley.” Room 26 Cabinet of Curiosities, blog entry posted April 2, 2009. http://beineckeroom26.library.yale.edu/?s=phillis+wheatley [accessed August 28, 2011]. Original images from Yale University: Beinecke Rare Book and Manuscript Collection.
Edwards, Ben. “Black History Month: A Tribute to Phillis Wheatley”, TeachHistory, blog entry posted February 9, 2010. http://teachhistory.com (accessed August 28, 2011).
“Illustrations for Phillis Wheatley, Poems on Various Subjects.” PBS: Africans in America. http://www.pbs.org (accessed August 28, 2011).
“Phillis Wheatley: America’s First Black Woman Poet.” Archiving Early America. http://www.earlyamerica.com (accessed August 28, 2011).
“Letter to Reverend Samson Occum.” PBS: Africans in America. http://www.pbs.org (accessed August 28, 2011).
Paul Reuben, “Chapter 2: Phillis Wheatley (1753-1784).” PAL: Perspectives in American Literature. A Research and Reference Guide. http://www.csustan.edu/english/reuben/pal (accessed August 28, 2011). |
You may have heard of the ‘marshmallow experiment’, one of psychology’s best know studies.
Stanford University researcher Walter Mischel was interested in children’s ability to delay gratification. He designed a study where toddlers and preschoolers were invited into his lab. They were shown a marshmallow (or cookie) and told they could eat it right away, or they could wait a short time while the experimenter stepped out. If they delayed eating the treat, they were promised that when the experimenter returned, they could have an extra treat as well.
The researcher then left the room and the children were observed for up to 15 minutes. Walter discovered that toddlers had almost zero capacity to wait. Invariably they ate the treat within moments of the experimenter leaving the room. But about 30 percent of preschool children were able to control the impulse to scoff the goody. They waited for 15 minutes so that they could enjoy two treats rather than one.
Why do we need self control?
This is where the marshmallow experiment gets interesting. About a decade after the original experiments, Walter noticed that some peers of his children who had completed the experiment (and been low-delayers – that is, they ate the treat without waiting) were not doing well at school. He began running follow up experiments that have continued to this day. Here’s what he has found:
Compared to low-delayers, children who, at age four, were able to delay gratification by controlling their impulse to eat the treat
- did better at school (by a VERY long way)
- experienced less stress and anxiety
- were less likely to abuse alcohol or drugs
- have better relationships (when aged in their 40s)
- enjoyed greater levels of wellbeing and psychological adjustment.
Other researchers followed 1000 New Zealand children from birth until they were 32 years-old. They found that childhood self control predicted physical health, dependence on alcohol and other drugs, financial status and even criminal behaviours. Then they compared life outcomes in 500 pairs of British fraternal twins (same sex), again finding that the sibling with higher capacity for self-control consistently had superior outcomes. The twin who, at age five, had higher self control was less likely to smoke, had better grades and showed better behaviour at age 12 than the less regulated twin.
In short, if there is one attribute that predicts success in life, it may well be the capacity to regulate, restrain and control ourselves.
- Self control allows our children to persist at tedious challenges (like study) without checking their devices every 45 seconds.
- Self control helps them maintain appropriate relationships with others (not whacking a sibling, or grabbing a stranger just because they’re attractive).
- Self control is what it takes for our teens to say no to a peer when they tell them ‘everyone’s doing it’, before trying to get them to drink that alcopop.
So if it’s so important, how do we build self control in our kids?
Step 1: buy a packet of marshmallows …
Ok, I’m half kidding. But seriously, read this in-depth summary of the experiment and try it with your kids, regardless of their age. The great thing about doing the experiment is that you can then discuss what it means.
Research tells us that there are some other effective things we can do to build self control:
- In the marshmallow experiment, children who were successful stopped focusing on the object of their desire. They distracted themselves. They used mental processes to shift their focus. So teach your kids that when they want to pick up their phone and ‘just check it one more time’, they need to distract themselves and study! Or teach them that when they want to drink that alcohol or smoke that cigarette, they can distract themselves by walking away, drinking something else, or whatever works for them.
- The children in the experiment also did some creative thinking exercises, such as pretending that the marshmallow wasn’t real. Instead they envisaged it as being surrounded by a picture frame, or pretended it was a cloud. This sounds lame, but perhaps your kids can pretend that the alcohol is a toxic chemical. Or their phone is a self-detonating device that can’t be touched or it will explode.
- The children in the marshmallow experiment who were successful also had a clear goal. They knew that success would bring an additional reward, and they wanted it. Help your kids focus on the rewards of studying, or the rewards of staying in control by not taking that first sip.
- We need to be an example. If our children watch us endlessly tap our phone screen, veg out in front of the TV and thoughtlessly down another coke and bag of chips, they’re not going to value self control because we don’t. It’s critical that we set an example by showing some control ourselves.
- Remember that toddlers can’t exercise self control effectively at all! Let nature take its course. As the brain develops and we can think ahead (using the pre-frontal cortex), our children will improve their capacity for self control. But don’t expect big things prior to at least age four (30 percent of the time), and realistically, age six-to-eight for higher levels of control.
- Practise! But don’t make your children wait for stuff just so you can try and develop their self control. You’ll only develop resentment. Instead, focus on why it is necessary, and what they’ll get when they’ve waited. For example, good friends, high grades, a safe trip home (without a crash or DUI), or the ability to play the piano well, and other benefits of self control need to be discussed. And then let them enjoy those benefits.
How much self control do your kids have? Would they pass the marshmallow test?
More from Kidspot:
- Why your teenager’s brain is like a Ferrari with bicycle breaks
- 5 simple solutions to raising responsible kids
- How do I teach my kids self-control and responsibility? |
Ten years ago, billions of humans had their worldview upended when a group of astronomers announced that the solar system only contains eight planets. Now, the same guys are trying to rewrite our childhood mnemonics once again. A ninth planet may exist after all, and it isn’t Pluto.
In January, Caltech’s Konstantin Batygin and Mike Brown (the astronomer credited with killing Pluto) shared compelling evidence of a planet larger than Earth and over five hundred times further from the Sun. Planet nine hasn’t been spotted—its existence is inferred by the improbable orbits of a handful of distant, icy objects. A race is on to find the mysterious world, and help is coming from all corners of the astronomical community.
“I’ve never seen anything like this happen before,” Brown told Gizmodo. “People look at the evidence and they are convinced. It almost makes me worried.”
Planet nine’s overwhelmingly positive reception is indeed rather odd. This isn’t the first time astronomers have speculated about a distant world sitting in or beyond the icy ring of primordial rocks known as the Kuiper belt. They’ve been doing so for decades. As Brown puts it, “Anytime anything funny happens in the outer solar system, somebody will jump up and down and say planet.”
But in every prior instance when astronomers have cried planet, the case has unraveled upon further analysis. This time, the evidence has only grown stronger. The first hint came in 2003, when Brown spotted a 600 mile-wide object circling the Sun on a highly elliptical path, far beyond the outer limit of the Kuiper belt.
Sedna, named after the Inuit goddess of the sea, was the coldest, most distant known object to orbit the Sun, and nobody could explain how it got there. In a paper published the following year, Brown and his colleagues speculated Sedna could have been dragged into its extreme orbit by a passing star or an unseen planet. For more than a decade, it remained an isolated curiosity.
Then in 2014, astronomers Chad Trujillo and Scott Sheppard announced the discovery of another distant object on a Sedna-like orbit, followed by a set of six Kuiper belt objects that share a bizarre orbital feature. Each of these icy rocks traces an elliptical path that loops out in the exact same part of the solar system. What’s more, all of their orbits are all tilted the same direction, pointing about 30 degrees down relative to the ecliptic plane (the plane in which planets orbit the Sun).
Based on our understanding of Kuiper belt dynamics, any one of these orbits is extremely unlikely. The chance of all six being some sort of grand cosmic coincidence? Approximately one in 14,000.
That’s when Batygin, a theoretician, and Brown, an observer, decided to put their heads together. “Our initial goal was to demonstrate that this was not a planet—that it’s some other dynamical effect,” Batygin said.
And yet, after two years of calculations and supercomputer simulations, a planet is what they found in the math. It turns out Sedna, all six Kuiper belt objects, and a handful of other weird rocks that orbit perpendicular to the plane of our solar system, can all be explained by a distant planet roughly ten times the mass of the Earth. “What we’re really predicting here is not just the existence of a planet, but a physical process through which the shape of the outer solar system is explained,” Batygin said.
According to Batygin and Brown’s calculations, Planet nine sits in an elongated, “anti-aligned” orbit—its point of closest approach to the Sun is directly opposite that of all other planets. It takes the frigid world 10 to 20 thousand years to complete a full orbit, and at its furthest point, it’s roughly 1,200 Earth distances (a hundred billion miles) away.
In January, Batygin and Brown published their findings in the Astronomical Journal. The announcement that a ninth planet may exist after all was not only embraced by the millions of laypersons who could finally fill the dark, Pluto-shaped holes in their hearts, but also by the scientific community. Folks with expertise ranging from the Big Bang to Saturn’s rings started asking whether a phantom planet may be lurking in their data.
At this point, if astronomers are correct about Planet nine, it’s only a matter of time before we find it.
The obvious way to prove the existence of a planet is to actually see the thing. In Planet nine’s case, that’s going to be tricky, because objects thirty times further from the Sun than Neptune on a good day don’t reflect a lot of light. But Brown, who’s built a career around finding small, distant Kuiper belt objects, is optimistic that Planet nine can be spotted.
“In principle, this is exactly the same thing we do to look for KBOs,” Brown said. “You take a picture, go back, take another picture later, and see if something moved. If you told me exactly where Planet nine was, I could find it pretty easily.”
The trouble is, we don’t know where Planet nine is, and its entire orbit is freakin’ enormous. And while astronomers can bag hundreds of random Kuiper belt objects by simply pointing a telescope at the sky, finding a specific object way off in the cosmic boondocks is going to be tougher.
“For KBOs, we’re interested in a statistical sample,” Brown said. “For Planet nine, we just want to find it. So we have to be very systematic about surveying the sky, and we can’t leave any patch undone.”
The best instrument for this job—both in terms of sensitivity and wide field of view—is Subaru, an 8.2 meter optical-infrared telescope located on the dormant volcano of Mauna Kea, Hawaii. Batygin and Brown have already put in a request for time on the popular telescope this fall. Meanwhile, several of their colleagues are bringing the southern hemisphere into the planet hunt, using a well-placed dark energy camera at an observatory in Chile.
But you don’t need to be good with a telescope to help find Planet nine. Agnès Fienga, a planetary dynamicist at the Nice Observatory in France, has an entirely different take on how we can locate the beast— NASA’s Cassini probe.
Since 2003, Fienga and her colleagues have used radio ranging data collected by the Cassini probe’s navigational system to precisely track the motion of Saturn. By doing so, they’ve constructed detailed models of the movement of all planets and major asteroids in the solar system. When Batygin and Brown published an orbital trajectory for a ninth planet, Fienga realized that her models could help narrow the search. “It’s not too complicated to add a supplementary planet and just test the theory,” Fienga told Gizmodo.
By sticking Planet nine in a solar system model calibrated with over ten years of Cassini data, Fienga and her colleagues have already ruled out half of the planet’s possible positions in the sky. “This study is awesome,” Batygin said, noting that the positions Fienga’s team eliminated include perihelion—the planet’s closest approach to the Sun. This independently confirms Batygin’s view that the planet currently sits in a more distant orbit.
Meanwhile, Nick Cowan of McGill University has thought of yet another way we can detect Planet nine—through its heat signature. Even an icebox of a planet like this one emits a small amount of energy at millimeter radio wavelengths. This turns out to be the same type of energy cosmologists use to study the birth of the universe.
“I am not an expert on Planet nine at all, nor am I a cosmologist,” Cowan, who studies the composition of exoplanet atmospheres, told Gizmodo. But when his colleague Gil Holder suggested that Planet nine’s heat signature might be detectable with the instruments used to study the cosmic microwave background (CMB)—the ubiquitous energy signature left over from the Big Bang—Cowan’s interest was piqued.
“I did a calculation, and came up with a surface temperature of 20 to 40 Kelvin,” Cowan said. That’s insanely cold, and it means Planet nine radiates about 2,000 times less heat than Uranus or Neptune. “I thought this crackpot idea would be over at this point,” he said.
When Cowan brought his calculations back to Holder, he learned he was mistaken. “Turns out, we use Uranus and Neptune to calibrate CMB [experiments] because they’re really bright,” he said. “2,000 times colder is totally doable.”
Cowan, Holder, and Nathan Kaib of the University of Oklahoma wrote up a paper on the idea, which is currently in review at The Astrophysical Journal. Cowan is hopeful that next-generation cosmology experiments will be able to detect Planet nine, or at least narrow the search. And if we’re really lucky, that faint heat signature might already exist in somebody’s CMB data.
Batygin, for his part, continues to run model simulations. Several weeks back, those models got a big boost when Michele Bannister of the University of Victoria, Canada, revealed yet another Kuiper belt object on the same funky orbit as Planet nine’s original flock of six. “Our biggest worry was that the next set of objects we discover are going to destroy the pattern—that our brains had somehow tricked us,” Batygin said. “Instead, the first new object is exactly where our models say it should be. It basically falls on the mean.”
Although we should save the champagne for hard proof, most astronomers agree that the case for a large, unseen planet beyond the Kuiper belt has never looked better. “I am not one hundred percent sure if there is a planet or not,” Fienga said. “But I think in a year we should have almost a definite answer.”
And if we do discover a Planet nine? It’ll certainly expand our perspective on the solar system, just as discoveries of Kuiper belt objects did in the early 2000s. It’ll help us piece together our celestial history—how the planets formed, why they’re all so different, and how they arrived in their present orbits. And it’ll shed light on the diversity of worlds we can expect to find orbiting other stars.
“The most exciting thing about Planet nine to me is that it’s uncharted territory,” Cowan said. “You do the math and realize, you could easily hide a planet out there, maybe more than one. Nature is amazingly good at making planets, and she puts them wherever the hell she wants.”
Batygin agrees. “I think the one thing we we can be certain of,” he said, “is that the solar system hasn’t run out of mysteries.”
Correction 4/9/16: An earlier version of this article stated that Batygin and Brown published their recent findings on Planet nine in the Astrophysical Journal. In fact, it was the Astronomical Journal. The text has been corrected. |
By the Middle and Late Jurassic, dinosaurs had taken over the world. There were herds of Apatosaurus; each adult was as large as five or six elephants. Allosaurus, a two-ton meat-eater, waited in the bushes for its next meal; it needed to eat often to fill its appetite. Bony plates protected slow, steady Stegosaurus, which had little fear of predators. The land quaked with dinosaur footsteps. Dinosaurs controlled this Jurassic world.
Canadian Museum of Nature
Pangaea continued to break apart in the Jurassic. It was splitting both north and south, and east and west. The land masses were beginning to resemble the shapes they have today. The Tethys Sea separated the southern land mass, called Gondwanaland, from the northern mass, called Laurasia. Laurasia consisted of North America, Europe, and Asia. Sometimes, probably because of sea level changes, it's likely there were land connections between Gondwanaland and Laurasia. Dinosaurs were very similar in North America and eastern Africa in the Late Jurassic. The Atlantic Ocean was still very narrow, and there was probably a land bridge that allowed the dinosaurs to migrate between the two continents.
Get to know the Middle and Late Jurassic dinosaurs.
Check out these individual profiles:
The northern part of the Atlantic Ocean began to open during the Jurassic, and it separated Laurasia into eastern (Europe and Asia) and western (North America) land masses. There were probably land bridges that connected these two land masses across the north when the sea level dropped. Antarctica gradually broke away from Gondwanaland and was over the South Pole by the Early Cretaceous. The continents were drifting apart at a rate of about a quarter of an inch to three inches a year (which is about as fast as a human fingernail grows).
All these changes in the continents changed the way the ocean waters flowed. Cold ocean currents in the southern hemisphere produced temperate climates in what is now South America, southern Africa, Antarctica, India (an island off eastern Africa), and Australia. The rest of the world was also warm and moist, and the Triassic deserts were shrinking and were gone by the Late Jurassic. There were no polar ice caps.
In this dry and semi-dry Jurassic landscape, conifers dominated wherever trees grew. Except for dinosaurs, the Jurassic plants and animals were much like those of earlier times. There were many ferns, tree ferns, cycads, ginkgos, and horsetails. Grasses had not yet evolved, but some ferns may have served as low ground cover. |
In fact, quartz resonator is an analog of the oscillation circuit based on the capacitance and inductance.
How it works crystal based on the piezoelectric effect.
The basis of crystal is a quartz plate. Quartz - is one form of silica SiO2. The crystal is an electromechanical oscillation system. Any oscillation system has its own resonant frequency. In crystal also has a nominal resonant frequency. If a quartz plate attached to an AC voltage which coincides with the resonance frequency of the quartz plate, the resonance occurs and the amplitude of the oscillation frequency increases sharply.
Applications quartz crystals - a highly stable oscillator clock signal and the reference frequency, the circuit frequency selection, frequency synthesizers, etc. |
what is the meaning of intensity of sound wave?
Sound intensity or acoustic intensity ( I ) is defined as the sound power P per unit area A. Though the usual context is the noise measurement of sound intensity in the air at a listener's location as a sound energy quantity.
Since Sound waves are introduced into a medium by the vibration of an object.The greater the amplitude of vibrations of the particles of the medium, the greater the rate at which energy is transported through it, and the more intense that the sound wave is.
This conversation is already closed by Expert |
By David Croushore
The world population is expected to reach 7 billion in the next year, before climbing as high as 10 billion this century. In the past, population projections like these have often underestimated future population growth.
When considering the world population, it is common to ask whether or not we have enough natural resources, food, water, and energy, to continue to sustain our growing population. However, this question ignores a crucial factor. The issue has never been how many resources we have, but how efficiently we can harness and utilize them.
The steep slope of the population line coincides with the spread of agricultural technology throughout the world. Increased farm yields have continually decreased the cost of food, and advances in sanitation (and modern medicine) have decreased the rate and severity of diseases.
The challenge we face as a world civilization going forward is to continue to pioneer new and efficient means of food and energy production, sanitizing water, and combating diseases of civilization.
Food and energy production must be efficient and safe. In the developed world, food recalls are rare, but still too frequent. Poor agricultural policy has contributed to this issue by stressing the use of ineffective and misguided nutritional labeling over food quality regulation. Efficient energy exists, in the form of nuclear power, but the NIMBY contingent limits our ability to dispose of the (safe) nuclear waste. Electric cars threaten to stress the energy grid during off-peak hours, creating a negative externality in the absence of nuclear power (which does not have variable output, but rather produces at peak levels constantly, creating a symbiosis between electric cars and nuclear power).
Despite these limitations, the next generation of innovative technologies has begun to appear. Genetically engineered seeds produce higher crop yields without sacrificing nutrition (though, it should be noted, our dependence on corn poses the most dire systemic health risk in the modern world, far exceeding the inevitable rise of anti-biotic-resistant diseases). Geo-spatial mapping and micro-meteorological analysis technologies will increasingly allow for efficiency analysis of farming, manufacturing, and even residential improvement. These and other innovations should provide hope for the future of our world population as they streamline the production and distribution of food and energy.
There can be little doubt that through increased efficiency in the production of food and energy, our world can sustain a larger population. Vast areas of land remain sparsely populated, so crowding cannot be considered a factor. As we have witnessed over the last century, innovation always arrives in time to meet the challenge, so we should fully expect the population of the world to continue to increase, and welcome the growth (along with its very positive effect on our bottom lines). |
Who recalls the dates of the Byzantine Empire? Or that the Ohlone Indians spoke one of the Utian languages? Details from social studies are easy to forget once we graduate to the real world. Still, such primers in history, geography, politics, and anthropology are crucial to our children’s education.
How do you know if your child’s social studies curriculum stacks up? Check out our grade-by-grade milestones to understand your state and national standards.
In the classroom
The focus in fourth grade is on students’ home states. Fourth-graders also start to learn the basics of democracy — starting with local, state, and national governments — as they explore the rationale for rules and laws. Fourth-graders are introduced to early U.S. history, building the foundation for more in-depth study in future grades.
Students will learn to use a variety of resources, including social studies textbooks, the Internet, newspapers, and primary sources (letters, diaries, speeches, photographs, and autobiographies). You can expect them to make and use timelines, graphs, charts, and maps to interpret historical data and to complete projects that include interviewing, debating, researching, taking virtual field trips, and role-playing to reenact events. The class may go on a field trip to a history museum or the state capital.
“Children enjoy learning social studies most when it relates to their personal lives,” says teacher Tonya Breland, the recipient of a Milken Foundation National Educator Award. “As they learn about the history of their state and the early history of our country, it is important that they see the connection to their own life and culture. Social studies is inclusive of culture, customs, traditions and history.”
Fourth-graders are expected to learn about our country’s five regions, the Northeast, Southeast, Southwest, Midwest, and West. They should gain an understanding of the physical characteristics (canyons, cliffs, deserts, mountains, lakes, etc.), features, natural resources, history, and climate of these regions.
In addition, students will be expected to learn these regions’ cultures, including customs, food, and arts, while exploring how different cultural groups have contributed to the United States. Typical activities include researching a region to create a travel brochure, a PowerPoint presentation, or a student museum.
Children in fourth grade study state history by exploring culture, economics, and geography. They’re expected to identify the customs, celebrations, and traditions of various groups of people and to compare the way families lived long ago to the way they live now by surveying jobs, transportation, food, literature, art, values, and celebrations. Classrooms should also include lessons on early settlers and Native Americans.
To learn their state’s geography and physical features, students are sometimes asked to build a three-dimensional relief map and label mountain ranges, rivers, and cities. Other projects might include designing a brochure that highlights state history, facts, and points of interest or building a model of a historical building like the state capitol. Fourth-graders are also expected to know state natural resources and study the difference between renewable resources (for example, water and forests) and nonrenewable ones (coal and oil).
Fourth-graders spend time studying maps, and they should expect to know how to use an elevation or a climate map and learn how to interpret a map using the legend, scale, compass rose, and key. Children are often asked to compare maps to glean pertinent information — for example, a change in population growth or density over time.
In class children examine current issues and events around the world using TV news programs, newspapers, magazines, and the Internet. The class might discuss how events affect students’ lives or compare them to past events. Discussing current events raises students’ awareness of the world and helps them connect the present with history and with information learned in other subjects. It also increases your child’s ability to think critically and analytically.
A sample of students nationwide take the National Assessment of Educational Progress test — otherwise known as the Nation’s Report Card — in social studies in 4th, 8th, and 12th grade. The latest results are from 2006. The questions give you an indication of what students are expected to know, and the results tell you how students in your state are performing in comparison to their peers in other states. Below are sample test questions from the 2006 tests.
What you should expect your child to know by the end of fourth grade:
- Read and interpret maps
- Identify the 50 states and their capitals
- Know key events of her state’s history
- Identify state and national symbols such as the American flag and the Statue of Liberty
- Tell you about the five regions of the United States
- Name the political leaders of her city and state
- Tell you about the Native American tribes that lived in her state |
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In environments that use static routing, routes and route information are entered into the routing tables manually. Not only can this be a time-consuming task, but also errors are more common. Additionally, when there is a change in the layout, or topology, of the network, statically configured routers must be manually updated with the changes. Again, this is a time-consuming and potentially error-laden task. For these reasons, static routing is suited to only the smallest environments with perhaps just one or two routers. A far more practical solution, particularly in larger environments, is to use dynamic routing.
In a dynamic routing environment, routers use special routing protocols to communicate. The purpose of these protocols is simple; they enable routers to pass on information about themselves to other routers so that other routers can build routing tables. There are two types of routing protocols used the older distance vector protocols and the newer link state protocols.
Distance Vector Routing
The two most commonly used distance vector routing protocols are both called Routing Information Protocol (RIP). One version is used on networks running TCP/IP. The other, sometimes referred to as IPX RIP, is designed for use on networks running the IPX/SPX protocol.
RIP works on the basis of hop counts. A hop is defined as one step on the journey to the data's destination. Each router that the data has to cross to reach its destination constitutes a hop. The maximum number of hops that RIP can accommodate is 15. That is to say that in a network that uses RIP, all routers must be within 15 hops of each other to communicate. Any hop count that is in excess of 15 is considered unreachable.
Distance vector routing protocols operate by having each router send updates about all the other routers it knows about to the routers directly connected to it. These updates are used by the routers to compile their routing tables. The updates are sent out automatically every 30 or 60 seconds. The actual interval depends on the routing protocol being used. Apart from the periodic updates, routers can also be configured to send a triggered update if a change in the network topology is detected. The process by which routers learn of a change in the network topology is known as convergence.
Although distance vector protocols are capable of maintaining routing tables, they have three problems. The first is that the periodic update system can make the update process very slow. The second problem is that the periodic updates can create large amounts of network trafficmuch of the time unnecessarily as the topology of the network should rarely change. The last, and perhaps more significant, problem is that because the routers only know about the next hop in the journey, incorrect information can be propagated between routers, creating routing loops.
Two strategies are used to combat this last problem. One, split horizon, works by preventing the router from advertising a route back to the other router from which it was learned. The other, poison reverse (also called split horizon with poison reverse), dictates that the route is advertised back on the interface from which it was learned, but that it has a metric of 16. Recall that a metric of 16 is considered an unreachable destination.
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An ecosystem is an ecological community comprised of biological, physical, and chemical components, considered as a unit.
NOS scientists monitor, research, and study ecosystem science on many levels. They may monitor entire ecosystems or they may study the chemistry of a single microbe. This wide range of data is collected into combined assessments that describe current ecosystem health, predict the future state of an ecosystem, and evaluate different management strategies that may improve the health of an ecosystem.
NOS focuses its efforts on ecosystems that are given importance by legislative and executive orders. These areas include coral reefs, estuaries, national marine sanctuaries, national estuarine research reserves, and other ocean ecosystems. The areas are observed and studied to determine how they are affected by human actions. Strategies are then formed in order to best protect these valuable ecosystems in order to keep them safe and healthy. |
What’s Happening This Week
There is much more to explore in our calendar. Find other important events in literary history, authors' birthdays, and a variety of holidays, each with related lessons and resources.
Looking for age-appropriate book recommendations, author interviews, and fun activity ideas? Check out our podcasts.
Today is World Hello Day!
|Grades||5 – 12|
|Calendar Activity Type||Holiday & School Celebration|
World Hello Day began in 1973 to promote peace between Egypt and Israel. There are now 180 countries involved in the attempt to foster peace throughout the world, and letters supporting the effort have been written by people such as John Glenn, Colin Powell, Kofi Annan, and the United Nations Children's Fund (UNICEF).
Throughout history, important leaders and institutions have used letters to make their beliefs known and to convince others of the importance of peace and unity. Invite your students to study one of the letters below for its message promoting peace in some way:
- Dr. Martin Luther King, Jr.'s Letter from Birmingham Jail
- An Open Letter from American Jews to Our Government
- Yes, Virginia, There Is a Santa Claus
Have students examine one of the letters to determine the author's purpose in writing, and to identify words and phrases that were used to make the letters more meaningful to the reader. Then, have them use the ReadWriteThink Letter Generator to write a letter of their own promoting peace. More tips are available about using the Letter Generator. Students may choose to write about world conflict, or they may choose to write about issues closer to home, such as bullying or peer conflicts.
- The Nobel Peace Prize
This site provides a wide range of materials for students at all grade levels. Resources include information about the Nobel Peace Prize laureates, a timeline, and a series of informational articles.
- Jane Addams Peace Association
The Jane Addams Peace Association furthers the cause of peace by selecting and awarding children's literature that promotes the cause of peace, social justice, world community, and equality.
- Peace Corps Kids World
The material in this website will enhance social studies and literature lessons in all primary grades. Your students will want to revisit this site throughout the school year.
- Say Hello to the World
This site lists eight easy activities designed to celebrate world language. The activities are perfect for ESL and bilingual classes and are beneficial to all primary school students.
Grades K – 12 | Calendar Activity | September 21
Students brainstorm a list of current conflicts and why people fight. Groups discuss and present possible solutions and create posters that promote their particular solution. |
This is the seventh of nine lessons in the 'Visualizing and Understanding the Science of Climate Change' website. This lesson addresses climate feedback loops and how these loops help drive and regulate Earth's unique climate system.
In this video, students learn that scientific evidence strongly suggests that different regions on Earth do not respond equally to increased temperatures. Ice-covered regions appear to be particularly sensitive to even small changes in global temperature. This video segment adapted from NASA's Goddard Space Flight Center details how global warming may already be responsible for a significant reduction in glacial ice, which may in turn have significant consequences for the planet.
This resource consists of an interactive table with a comprehensive list of 29 Greenhouse Gases, their molecular structures, a chart showing a time series of their atmospheric concentrations (at several sampling sites), their global warming potential (GWP) and their atmospheric lifetimes. References are given to the data sets that range from the mid-1990s to 2008.
This activity is a greenhouse-effect-in-a-bottle experiment. The lesson includes readings from NEED.org and an inquiry lab measuring the effect of carbon dioxide and temperature change in an enclosed environment.
In this hands-on activity, participants learn the characteristics of the five layers of the atmosphere and make illustrations to represent them. They roll the drawings and place them in clear plastic cylinders, and then stack the cylinders to make a model column of the atmosphere.
In this experiment, students will observe two model atmospheres: one with normal atmospheric composition and another with an elevated concentration of carbon dioxide. These two contained atmospheres will be exposed to light energy from a sunny window or from a lamp. The carbon dioxide is produced by a simple reaction and tested using bromothymol blue (BTB).
This static visualization from Global Warming Art depicts the chemical characteristics of eight greenhouse gas molecules - carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), water (H2O), ozone (O3), sulfur hexafluoride (SF6), dichlorodifluoromethane (CFC-12), and trichlorofluoromethane (CFC-11).
In this activity, students learn about the relationship between greenhouse gases and global warming through a simple teacher demo or hands-on lab activity. Everyday materials are used: beakers, baking soda, vinegar, candle, thermometers, heat source such as a goose-necked lamp, etc. Students shine a light onto three thermometers: a control, an upside down beaker w/ a thermometer and air, and a beaker in which CO2 had been poured. |
Presentation on theme: "Where is fresh water found? What are some California water sources?"— Presentation transcript:
1 Where is fresh water found? What are some California water sources? Chapter 5 lesson 2 and 3Where is fresh water found?What are some California water sources?
2 Where does fresh water come from? What is fresh water?
3 Nearly 1 billion people don't have safe water to drink Nearly 1 billion people don't have safe water to drink. A child dies every 15 seconds from a lack of clean water. 1 in 4 children who die before age 5 worldwide, die of a water related disease. Children often walk miles every day to collect dirty water to drink.
4 Fresh Water1) Fresh water has some dissolved salts but less salt than ocean water.2) The water we drink is fresh water.3) The amount of fresh water on Earth is limited and is not evenly spread over the world.4) People should use water carefully!5) Most of Earth’s fresh water starts as rain or snow.6) The water from the rain and snow flow downhill and part of it goes in the ground.
5 About 7/10ths of Earth’s fresh water is frozen into ice and hard for people to use! Most of Earth’s ice is in Antarctica and Greenland.Glaciers form when the amount of snow that falls is greater than the amount of snow that melts.
6 Ground water is rain or melted snow that soaks into the ground. Aquifer is the layer of rock and soil that the groundwater flows through.Water table is the top level of groundwater in the aquifer. It gets higher with rains and snow and lower with droughts.Some people get their water from wells that go into the aquifer.
7 Water shed -Water from rain and melting snow flow downhill. -The water makes small creeks and join together to make streams and rivers.-The area near a river, where all the water drains into the river is the watershed.
8 ReservoirA lake forms when water collects in a low place that has higher land around it.A reservoir is an artificial lake that forms behind a dam.
9 Water! Some people get water from groundwater. Some towns have surface water, but it can have bacteria.Water is treated before people use it!
10 When water is treated it is pumped from a lake or river. Chemicals are added to make small particles stick to larger ones that sink!Chemical can be: Chlorine to kill bacteria
11 California’s waterDifferent areas of California get different amounts of rain.The northern coast gets more rain than the deserts.Fresh water comes from rain or snow.Southern California is dry, so it is hard to get enough rain!The southern coast of California receives drinking water from through a system of aqueducts because it is dry!
13 Aqueducts Many Californian’s get water from Aqueducts. Aqueducts are a system of pipes that carry water from rivers or lakes to places that need water.
14 Los Angles Aqueduct First part of system was build 100 years ago. Carries water from Owens River in Sierra Nevada.1970 second aqueduct was built.
15 The Colorado River Aqueduct Brings water to the City of San Diego.The Aqueduct carries water to Lake Mathews in Riverside County and then to San Diego.
16 Water Shed:The land that water flows across or under on its way to a river, lake or ocean.The amount of water in a watershed depends on how much water is used and collected.Reclamation:Water can be recycled and used again.The water (wastewater) is treated, but people cannot drink it, people can use it to water crops and lawn.
17 Rancho California Water District RCWD water comes from a variety of natural sources. Our natural sources include precipitation, surface stream flows and regional groundwater (aquifers). RCWD also purchases water from Metropolitan Water District of Southern California. This agency imports water from Northern California and the Colorado River. Water delivered to homes and businesses is a blend of well water (25 percent) and import water (70 percent). Water recycling which produces highly treated wastewater is used to irrigate some golf courses and large landscaped areas. Thirsty Southern California is using more and more recycled water for irrigation in order to save its precious well water and import water for drinking and household use. The RCWD managed groundwater basins are estimated to hold over 2 million acre-feet of water. The annual safe yield of these basins is approximately 30,000 acre-feet per year, which meets nearly half of the District's needs. Most of the remaining water demands are met with imported water purchased from Metropolitan Water District of Southern California. RCWD is also continuing to develop more use of reclaimed water for irrigation purposes. Surface water from Vail Lake is used to help replenish our groundwater supplies through recharge operations. Aquifers All aquifers managed by the District are located in the Santa Margarita Watershed. Oversight of all groundwater production within the Santa Margarita Watershed falls under the continuing jurisdiction of the United States District Court, San Diego and is administered under the auspices of a court appointed watermaster (the "Santa Margarita Watermaster"). An acre-foot equals about 326,000 gallons, or enough water to cover an acre of land about the size of a football field, one foot deep. An average California household uses between one-half and one acre-foot of water per year for indoor and outdoor use. Much of California's water is stored as snow in the Sierra Nevada mountains.The RCWD Consumer Confidence Report is published annually. It typically provides information about where your water comes from, what it contains and other general public consumer information
19 Test your knowledge!Water can leave a lake and flow into the ground or evaporate into the air. T/F?Name one chemical that is added to kill bacteria in water.A measure of the amount of salt in water is called___?What percent of water is outside of the oceans?Water cannot be evaporated from the ocean. T/FThere is plenty of fresh water, and you can waste as much water as you want. T/F?
20 7) A system of pipelines that carry water from a river or lake to the area where it is needed is called_________?8) Water can be recycled and used again in a process called _________?9) A layer of rock or soil through which groundwater flows is_______?10) The area from which water drains into a river is_______?
21 HomeworkWrite a letter to your family and neighbors in which you explain the facts you learned about fresh water as evidence to convince them to conserve fresh water.Questions to consider: What do you think will happen if we continue to use fresh water at this rate?Is it fair that some people have limited water and have to drink contaminated water? |
Factors influencing Cinnamon Teal nest attendance patterns. Setash, C. M., W. L. Kendall, D. Olson. 2020. IBIS. DOI: 10.1111/ibi.12838. VIEW
Cinnamon Teal, Spatula cyanoptera, are one of the most enigmatic duck species in North America as well as one of the most coveted by hunters and birders, alike. Until recently, waterfowl managers have lumped Cinnamon Teal in with the closely-related Blue-winged Teal, Spatula discors, when setting harvest limits, prioritizing breeding habitat, and estimating abundance because the females are nearly impossible to differentiate and their breeding habitats often overlap. The need to address differences in population size, habitat preferences, and behavior has recently been highlighted by the US Fish and Wildlife Service, however. The mechanisms driving their behavior during the breeding season may reveal important differences in habitat selection preferences and the selective forces behind them.
During incubation, all waterfowl must make decisions on when and for how long to leave their eggs unattended in order to maintain proper egg temperatures while ensuring they meet their own energetic requirements. When environmental conditions (e.g., temperature, precipitation, etc.) vary from day to day, the incubating parent can adjust their behavior to take advantage of beneficial conditions or face reproductive repercussions from failing to do so. In Cinnamon Teal, this can mean altering the number of recesses taken during a given day of incubation or altering the duration of a single recess. In theory, longer recesses could expose the nest to potential predators for more time, but more frequent recesses might result in activities that draw attention to the nest (i.e., movement, disturbed vegetation). The goals of researching incubating Cinnamon Teal were to determine whether individuals exhibited any patterns in incubation behaviors and whether those patterns were related to weather or vegetation around the nest.
Figure 1 A female Cinnamon Teal leaving her nest with her newly hatched ducklings © Casey M. Setash
In southern Colorado, one of the more heavily used areas of the Cinnamon Teal breeding grounds, incubating hens did, in fact, exhibit patterns in incubation patterns related to weather. Vegetation around the nest did not impact their incubation behavior as predicted, but they did make use of warming temperatures throughout the day to take foraging breaks. Birds on nests close to hatching took longer recesses in the afternoon, while those on newly-initiated nests took longer recesses in the morning and evening. In addition, warmer daily ambient temperatures resulted in a lower incubation constancy, which describes the proportion of the day a bird spends on the nest. In other words, if the temperature increased 30˚C, birds were predicted to decrease their incubation constancy by 11.2%. That equates to 161.3 more minutes spent off the nest foraging during which time the eggs are at a lower risk of getting too cold and females can replenish their energetic reserves.
The observed incubation patterns are similar to those of other small-bodied ground nesters and make sense from an energetic standpoint. The hottest part of the day affords incubating birds the opportunity to forage without putting their eggs at risk of cold temperatures and probably also coincides with the lowest predator activity levels at this Colorado study area. Research on Cinnamon Teal nesting behaviors can provide a clearer picture of the evolution of these behaviors as well as allow future researchers to disturb nesting birds less frequently by utilizing known timing patterns of incubation recesses.
Gammonley, J. H. 2012. Cinnamon Teal (Anas cyanoptera), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology. VIEW
Hohman, W. L. 1991. Incubation rhythm components for three Cinnamon Teal nesting in California. Prairie Naturalist 23: 229-233. VIEW |
Ideas to make fun learning for kids in learning something is unlimited and you could always start and think from the simplest thing. For kids in second grades,learning sight words is the time when they were taught to memorize words by sight in order to remember immediately. Fun and engaging ways to teach sight word lists can be personalized by children’s favorite toys or their surroundings. As an example, you can print a second grade sight word list and build up blocks with alphabets on it then make a tower based on the list. Try five to create five stacks at one practice and keep rotating on the list each week. This can help children to memorize and arrange words quickly.
Sight word as an important part in literacy is to be read quickly and without paying too much attention. It means that you see the words and can read without having to speak them out. On the second grade sight word list mentioned are words that are useful in conversation. Some of the sight word list for second grade is noted as example below:
Besides those words, you can add any words to be used on the second grade list. Knowing how and why it is important to know about sight word lists influenced your second grade children about how fluent you are as a reader. Different kids has difference pace.
The use of sight word list is to recognize a word instantly and read it at the same time without sounding it. The second grade sight word list also helps students in adding more new vocabulary because teachers can make a personalized sight word list according to student capabilities. When children are able to read words automatically, they can increase fluency skills by knowing phonetic patterns. This will develop as a lifelong skill because we need to be quick and understand the context of words in sentences. If you only keep say the word and use it in a sentence, the result won’t come out effectively since the aim is to let students read the word within a sentence. Without sight words, you might have speech sound mixed up and the text make little sense. |
Appropriate Fertilizer Use
The goal of applying fertilizer is to supply just enough to meet the needs of the plant. Too much fertilizer can run off into nearby waters, leach into groundwater or encourage weeds. A plant’s health should be the guide. If plants suffer from a lack of vigor, retarded growth, sparse foliage or leaf discoloration, they may be nutrient deficient, although improper drainage or inadequate aeration are more likely the cause.
How to get started:
- Test soil to determine whether there really is a nutrient deficiency.
- If supplemental nutrients are necessary, choose a renewable natural fertilizer — preferably produced locally — over synthetic, petrochemical-based fertilizers or mined products like rock phosphate. Synthetic fertilizers require much more energy to produce than natural options such as blood meal, bone meal, fish meal or emulsion, and kelp meal.
- Whenever appropriate, use single-nutrient fertilizers instead of so-called complete fertilizers that contain nitrogen, phosphorus and potassium. For example, if soil is low in nitrogen but not in phosphorus and potassium, use blood meal, fish emulsion or another high-nitrogen natural fertilizer. Better yet, grow green manure.
- Add only the amount of fertilizer recommended in the soil test, no more. Follow the guidelines on the fertilizer label.
- Avoid contributing to water pollution by applying fertilizer only to the soil, not paved areas, and sweep stray particles into the planting bed. Do not use fertilizer near streams or drainage ways. |
There are different Types of Gearbox are here with different uses. In order to change the speed (RPM) or the output torque of a motor. A mechanical device needs to be used – a Types of Gearbox. The shaft of the motor is attached to one side of the gearbox. It offers a given torque as output and speed which is determined by the gear ratio. It is through the internal arrangement of gears within a gearbox.
How gearboxes operates?
All types of gearboxes operate in a similar manner. The direction that the gears rotate is contingent on the orientation and input direction of the gears. An example would be if the initial gear is revolving clockwise. The gear that it engages will be revolving in the opposite direction – counterclockwise. With multiple gears, this continues all throughout the line. The combination of various size gears and the quantity of teeth. Each gear has plays a major role in the speed of the shaft as well as the output torque. When the gear ratios are high, it allows for lower speeds and more output torque, whereas less output torque. Higher output speeds can achieve with lower gear ratios.
What are worm gears?
Among the old type of gears is one that is call the worm gear. It is basically a screw which is butt up against something that looks like a spur gear. It has slightly curved and angled teeth. The gear changes, by 90 degrees, the rotational movement. Due to the worm’s position on the wheel (or the “worm wheel” as it is known). The plane of movement changes as well.
How Do Worm Gears Work?
There is an electric engine or motor applies, through the worm, rotational power. When the worm spins against the wheel, the screw face then pushes on the wheel’s teeth. The wheel is thrust against the load. A worm gear is able to bear up with loads that can be described as high shock. Its noise level is relatively low and is also maintenance-free. However, they are not as efficient as other types of gears. A worm gear may use which enables the worm to rotate the gear easily in a right angle configuration. As a brake system, the prevention of the gear to shift the worm can be utilized. The worm gearbox is in a locked position when it is not active.
What Are Worm Gearboxes Use For?
There are many applications which require great speed and for loads which can be set up for right-angle applications. Worm gearboxes can used for:
- Escalator/Elevator Drive Systems
- Rolling Mills
- Benefits of the Worm Gearbox
Using worm gears has some advantages over standard gears. Benefits can include:
- It is self-locking – it is capable of stopping and holding load, as well as overhauling or the capability to function in reverse
- Worm gears support high overhung as well as thrust load
- It can support shock loads (100% for a helical bevel as opposed to 300% for a cone drive)
- It as a high torque even at low speeds
- Worm gears have a good level of repeatability
- The ratios of cone drives are exact
- Has no or zero backlash
- It has a consistent size with rise in ratio |
The Information Below Comes Directly From Science Alert
This fascinating animated map provides one of the best demonstrations we’ve seen of how modern Indo-European languages evolved over the past 8,000 years. The Indo-European languages are a group of more than 400 languages that contains everything from Polish and French to Icelandic and Hindi, and scientists have worked out that they all originally came from one single language spoken in the region of Anatolia, in present-day Turkey.
The animation, which was created by Business Insider’s science team, shows how the languages spread from Anatolia through farming to various parts of Europe and Asia, changing as they went until they eventually became the languages we recognise today. And it’s pretty crazy to think that such varied dialects all came from the same starting point.
The map is based on a seminal study led by evolutionary biologist Quentin Atkinson from the University of Auckland in New Zealand, which was published in Science back in 2012. In his research, Atkinson used the same computational methods that geneticists use to trace flu virus outbreaks to map the spread of language evolution around the globe.
To do this, Atkinson and his team looked at common words – such as hand, foot, mother, father, fire, water – from more than 100 ancient and modern languages, and then compared how similar these words were across different languages. They then used these similarities and differences in the same way that geneticists use DNA, to create a family tree of language. This allowed them to trace all the way back along the tree to find the root of modern Indo-European languages.
Watch the animation above, and get inspired by the fact that most of our ancestors started out speaking the same language. |
Students are introduced to the Multiplication Rule for both independent and dependent events. Using spinners, they compare probabilities found by looking at the sample space and by using the appropriate formula. They will learn what is meant by a conditional probability and find conditional probabilities, some from a table in a spreadsheet. Last, they will use complements of events to find probabilities of "at least one."
Before the Activity
Download the attached PDF and look over the information on the first page. Download and distribute the attached student TI-Nspire document (.tns file) and student worksheet for use during the activity.
During the Activity
Discuss the material from the activity pages and worksheet with students as needed.
After the Activity
Encourage students to summarize what they have learned from completing the activity. |
2 Objectives Understand the use of expert systems in Mineral prospecting Car engine fault diagnosisMedical diagnosisOil/mineral prospectingPlant/animal identificationStrategy games eg Chess
3 What is an Expert System? An expert system is computer software that attempts to act like a human expert on a particular subject area.Expert systems are often used to advise non-experts in situations where a human expert is unavailable (for example it may be too expensive to employ a human expert, or it might be a difficult to reach the location).
4 Examples of expert systems include Diagnosing a person’s illnessDiagnostics (car engine faults, circuit board faults etc)Prospecting for oil and mineralsTax and financial calculationsChess gamesIdentification of plants, animals, chemical compoundsRoad scheduling for delivery vehicles
5 What is an Expert System? An expert system is a knowledge-based system which attempts to replace a human 'expert' in a particular field. The system will consist ofa large database of knowledgefacilities for searching the knowledge databasea set of rules for making deductions from the dataAn engine to apply those rules (inference engine)
6 How Do Expert Systems Work? An expert system is made up of four parts:A user interfaceA knowledge baseA rules baseAn inference engine
7 User InterfaceThis is the system that allows a non-expert user to query (question) the expert system, and to receive advice. The user-interface is designed to be a simple to use as possible.
8 The knowledge baseThis is a collection of facts. The knowledge base is created from information provided by human experts.It is a database designed to allow the complex storage and retrieval requirements of the expert systems
9 The rules base This is made up of a series of ‘inference rules’ IF the country is in South AmericaAND the language is Portuguese,THEN the country must be BrazilThese inference rules are used by the inference engine to draw conclusions.The inference rules closely follow human reasoning.
10 The inference engineThis acts rather like a search engine, examining the knowledge base for information that matches the user's query.It is software that attempts to derive answers from the knowledge base using a form of reasoning.
12 How it works:The non-expert user queries the expert system. This is done by asking a question, or by answering questions asked by the expert system.The inference engine uses the query to search the knowledge base and then provides an answer or some advice to the user.
13 Where Are Expert Systems Used? Medical diagnosis (the knowledge base would contain medical information, the symptoms of the patient would be used as the query, and the advice would be a diagnose of the patient’s illness)
14 Where Are Expert Systems Used? Playing strategy games like chess against a computer (the knowledge base would contain strategies and moves, the player's moves would be used as the query, and the output would be the computer's 'expert' moves)
15 Where Are Expert Systems Used? Providing financial advice - whether to invest in a business, etc. (the knowledge base would contain data about the performance of financial markets and businesses in the past)
16 Where Are Expert Systems Used? Helping to identify items such as plants / animals / rocks / etc. (the knowledge base would contain characteristics of every item, the details of an unknown item would be used as the query, and the advice would be a likely identification)
17 Where Are Expert Systems Used? Helping to discover locations to drill for water / oil (the knowledge base would contain characteristics of likely rock formations where oil / water could be found, the details of a particular location would be used as the query, and the advice would be the likelihood of finding oil / water there)
18 Where Are Expert Systems Used? Helping to diagnose car engine problems (like medical diagnosis, but for cars!)Two types:OnboardIn workshops
19 Can Expert Systems Make Mistakes? Human experts make mistakes all the time (people forget things, etc.) so you might imagine that a computer-based expert system would be much better to have around.
20 Advantages of Expert Systems An ES can store far more information than a human.Expert systems provide consistent answers.ES does not 'forget’ to ask important questions, or make mistakes.Reduces the time taken to solve a problemData can be kept up-to-date.
21 Data can be collected from many experts The expert system is always available 24 hours a day and will never 'retire'.The system can be used at a distance over a network.A less skilled workforce is neededOpportunity to save moneyPeople/areas can access expertise they couldn’t otherwise afford
22 Disadvantages of Expert Systems Very expensive to set up in the first placeThe computer’s reasoning is only as good as the rules it has been givenThey have no 'common sense' (a human user tends to notice obvious errors, whereas a computer wouldn't)
23 Errors in the knowledge base can lead to incorrect decisions being made Mistakes made when entering facts/answers to questions can lead to incorrect decisionsNot possible to break ALL expert knowledge into facts, rules & probabilitiesNo human interaction/human touchConsiderable training is required to ensure the system is used correctly by the operators |
Hindi Alphabet Worksheets Learning Of Hindi Alphabet Exercise 01. Hindi writing practice sheets pdf. Help your kid to identify hindi alphabets with practice worksheet.
The better you pronounce a letter in a word, the more understood you will be in speaking the hindi language. Hindi worksheets and printables for kids. And make sure to check out at all of my alphabet activities here.
Help Your Kid To Identify Hindi Alphabets With Practice Worksheet.
Hindi alphabets have 13 vowels and 33 consonants and 3 conjuct consonants. Hindi alphabet ( हिन्दी वर्णमाला ) worksheets. Hindi alphabet exercise 04 hindi worksheets hindi source:
An Easy Way For The Kids To Learn Hindi In A Fun Filled Manner.
Let your child learn hindi alphabets easily by learning one alphabet at a time using our kindergarten hindi worksheets. Learn and master hindi alphabet with fun and joy coloring pages. Your child can learn hindi alphabets (varnamala) with 100+ worksheets.
Learn Hindi Alphabets, Numbers, Fruits, Flowers, Animals, Shapes, Vegetables And Much More Thru Our Worksheets.
These worksheets include fun exercises such as match with the correct picture, maze games, colour the alphabet, colour the shape etc. Parents or teachers may download our hindi alphabet writing and tracing worksheet in pdf file. We provide, our latest designed hindi alphabets worksheet for pupils under the age of 5 to 6.
Learning The Hindi Alphabet Is Very Important Because Its Structure Is Used In Every Day Conversation.
This is a very basic hindi worksheet. They have to join the letters to form a meaning full hindi two letter word. Hindi varnamaala, hindi alphabets, with pictures,similar sound in english, joining letters to make words, word examples with meanings and pronunciation in english, sounds introduction, understanding sounds of alphabets in hindi, order changed for better understanding, shabd rachna, learning hindi for kids, english to hindi, hindi to english
Worksheet Of Hindi Letter Worksheet 3 Letters 02 Hindi Source:
Printable worksheets for learning hindi alphabets, numbers, colors, shapes and lot more. Hindi alphabet writing practice book page. Hindi printable worksheets for writing practise. |
Teaching your kid to read doesn’t begin in the uterus. It’s not through flash cards and repetitive drills, it’s all through repetition and listening. Phonics, sight words, will all come in later. All these things will teach your son or daughter to connect certain sounds with certain words. If you do this from the beginning, your kid will have the ability to learn words at a much faster rate.
A frequent question that most parents have is: How to teach your child to learn to read? This is a very good question, but can also have quite a few answers. The first thing that you will need to do before anything else is to determine what sort of reading you intend on doing. There are all kinds of different reading strategies, from phonics to flash cards.
If your plan is merely to teach your child to recognize a word and then allow them to mimic that phrase after they have heard it several times, that is called phonics. Phonics is the most popular way to teach a child to recognize a word. They are also the easiest way for your child, because you can teach them and not by reading from a book. As soon as they’re hearing the word over, they’ll remember it.
Flashcards are another popular method. You’ll get them mixed up and you’ll have to return and reorder them. In the end, though, you might realize that flashcards are excellent for memorizing things also. They force you to consider the word that you want to memorize. This forces you to really think about the spelling of the word, which means you’ll learn it more accurately.
Another method that you can use is known as phonics and is really great for those who have trouble learning how to speak. Should you determine that this is the best method for you and your child, you should talk to a specialist in this area and find out what it is that you need to do. They will have the ability to help you figure out exactly what you need to do. There are some differences between phonics and other procedures of teaching a child to learn to read. An expert will be able to help you figure all that out.
Among the biggest questions people have when they start teaching their children to learn how to read is how to identify words which sound the same. 1 thing which experts suggest is to use sound patterns as a cue. If two words are pronounced the same and they’re placed next to each other on a webpage, you’ll know right away that you’ve found a frequent letter. This is very beneficial in helping children to understand how to recognize words.
When you are teaching your kid how to learn how to read, you will need to be certain that you don’t ever give up. Remember that reading is a constant procedure. Your child may not be able to recognize a specific letter at first, but as they get older, they’ll probably start to recognize more of these. If you give up, you’ll only be strengthening their lack of desire to learn.
When you need to learn more on how to teach your child to learn to read, there are loads of ways for you to learn. You could hire a specialist in this area or even study it yourself. Whichever method you choose, you’ll be teaching your child right from the start. Just make sure that you’re persistent and consistent.
There are numerous books out there on how to teach your child to learn how to read. The most popular books are those which provide a drill system for your child to practice. This is a excellent idea for kids that have trouble learning to read. Once your kid starts drilling the letters, they’ll immediately start to recognize words. This is a superb way for them to pick up the language.
In addition to having a book with drill lessons, there are also online programs which you can buy. These programs permit you to teach your child without ever seeing your child. The online lessons are incredibly convenient. They come in a variety of formats such as flash cards and DVDs. It is also possible to buy software that will teach your child the reading part of the program.
A excellent home-based reading program really can help you build an understanding of how to teach your child to learn to read. These programs are extremely effective, and they should be used for all ages of kids. You can begin small and work your way up to more complex activities as they get older. No matter what age your child is, learning to read is an important skill for them to have. It doesn’t matter if they are old enough to read their own books or if they’re too young to comprehend print on a webpage. Provided that they’re receiving their education from home, they should have no difficulty understanding the concepts being taught.Http Www.Abcmouse.Com Library_Account |
Pronoun agreement is also known as antecedent agreement. It forms one of the bases of proper English sentence construction. Ignoring the rule of pronoun agreement causes confusion about meaning of the sentence.
A pronoun is defined as a word used to refer to a noun in a long sentence or paragraph. In the sentence, "I went to Harry’s house but he was not in," Harry is the noun and the word used to substitute for Harry in the latter part of sentence is the pronoun. Thus, the word "his" is the pronoun.
Pronoun Number Agreement
Consider the following incorrect sentence. "I went to Harry’s house but they were not in." What is wrong with this sentence? The number of nouns does not match the pronoun number. This means there is a disagreement between noun and pronoun number. The noun, Harry, refers to one person and is singular. But the pronoun, "they"refers to more than one and is plural.
Pronoun Gender Agreement
Consider the following incorrect two sentences. "I borrowed Harry’s book yesterday. I will be returning her book back today." Does the noun match the pronoun gender? Harry is a masculine gendered noun while the pronoun refers to female gender. This is a disagreement of noun-pronoun gender.
Pronoun agreement rules apply rigidly to written English but not to conversational English. To write "someone lent me their book" is improper English as there is number and gender noun-pronoun disagreement. Someone is singular but the pronoun used, "they," is plural.
Speaking the same sentence in a conversation is proper and acceptable. Improper pronoun agreement is accepted in common English conversation jargon. When you say, someone lent me their book, previous knowledge and schemas about the background color your understanding of the sentence. You comprehend the exact meaning of the sentence despite the pronoun disagreement. |
A surprising study looking into the origin of asteroids and meteorites that collide with Earth has found that the vast majority come from a small selection of ancient planets.
As astronomers try to piece together the mysterious origins of the comet ‘Oumuamua, a team of researchers from the University of Florida believes it has found the origin of other cosmic objects in our solar system, specifically asteroids and meteorites that have struck Earth.
While we know that the main source of Earth’s meteorites is the inner asteroid belt, the research team has found that the vast majority of them are the result of a splintering of only five or six ancient, minor planets aeons ago.
In a paper published to Nature Astronomy, the team estimated that at least 85pc of the 200,000 or so asteroids in the inner belt were created as a result of this process, but the remaining 15pc may trace their origins to the same group of primordial bodies.
This somewhat surprising finding will be important for our understanding of how our own rocky planet came to be. Perhaps even more crucially, it could prove essential in how we might be able to protect ourselves against a planet-killing asteroid on a collision course with Earth.
‘We need to know what its nature is’
“These large bodies whiz by the Earth, so of course we’re very concerned about how many of these there are and what types of material are in them,” said Stanley Dermott, lead author of the study.
“If ever one of these comes towards the Earth and we want to deflect it, we need to know what its nature is.”
Dermott and his team were also able to demonstrate that the type of orbit an asteroid has depends on the size of the latter.
This suggests that differences in meteorites found on Earth appear because of the evolutionary changes that occurred inside a few large, precursor bodies that existed more than 4bn years ago.
“I wouldn’t be surprised if we eventually trace the origins of all asteroids in the main asteroid belt, not just those in the inner belt, to a small number of known parent bodies,” Dermott added. |
Digital radiography (digital X-ray) is the latest technology used to take dental X-rays. This technique uses an electronic sensor (instead of X-ray film) that captures and stores the digital image on a computer. This image can be instantly viewed and enlarged, helping the dentist and dental hygienist detect problems more easily. Digital X-rays reduce radiation 80-90% compared to the already low exposure of traditional dental X-rays.
Dental X-rays are essential, preventative, diagnostic tools that provide valuable information not visible during a regular dental exam. Dentists and dental hygienists use this information to safely and accurately detect hidden dental abnormalities and complete an accurate treatment plan. Without X-rays, problem areas can go undetected.
Dental X-rays may reveal:
Abscesses or cysts.
Cancerous and non-cancerous tumors.
Decay between the teeth.
Poor tooth and root positions.
Problems inside a tooth or below the gum line.
Detecting and treating dental problems at an early stage can save you time, money, unnecessary discomfort, and your teeth!
Are dental X-rays safe?
We are all exposed to natural radiation in our environment. Digital X-rays produce a significantly lower level of radiation compared to traditional dental x-rays. Not only are digital X-rays better for the health and safety of the patient, they are faster and more comfortable to take, which reduces your time in the dental office. Also, since the digital image is captured electronically, there is no need to develop the X-rays, thus eliminating the disposal of harmful waste and chemicals into the environment.
Even though digital X-rays produce a low level of radiation and are considered very safe, dentists still take necessary precautions to limit the patient’s exposure to radiation. These precautions include only taking those X-rays that are necessary, and using lead apron shields to protect the body.
How often should dental X-rays be taken?
The need for dental X-rays depends on each patient’s individual dental health needs. Your dentist and dental hygienist will recommend necessary X-rays based upon the review of your medical and dental history, a dental exam, signs and symptoms, your age, and risk of disease.
A full mouth series of dental X-rays is recommended for new patients. A full series is usually good for three to five years. Bite-wing X-rays (X-rays of top and bottom teeth biting together) are taken at recall (check-up) visits and are recommended once or twice a year to detect new dental problems. |
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In engineering, buckling is a failure mode characterized by a sudden failure of a structural member subjected to high compressive stresses, where the actual compressive stresses at failure are smaller than the ultimate compressive stresses that the material is capable of withstanding. This mode of failure is also described as failure due to elastic instability. Mathematical analysis of buckling makes use of an axial load eccentricity that introduces a moment, which does not form part of the primary forces to which the member is subjected.
Additional recommended knowledge
Buckling in columns
The ratio of the effective length of a column to the least radius of gyration of its cross section is called the slenderness ratio (sometimes expressed with the Greek letter lambda, λ). This ratio affords a means of classifying columns. All the following are approximate values used for convenience.
If the load on a column is applied through the center of gravity of its cross section, it is called an axial load. A load at any other point in the cross section is known as an eccentric load. A short column under the action of an axial load will fail by direct compression before it buckles, but a long column loaded in the same manner will fail by buckling (bending), the buckling effect being so large that the effect of the direct load may be neglected. The intermediate-length column will fail by a combination of direct compressive stress and bending.
In 1757, mathematician Leonhard Euler derived a formula that gives the maximum axial load that a long, slender, ideal column can carry without buckling. An ideal column is one that is perfectly straight, homogeneous, and free from initial stress. The maximum load, sometimes called the critical load, causes the column to be in a state of unstable equilibrium; that is, any increase in the load, or the introduction of the slightest lateral force, will cause the column to fail by buckling. The Euler formula for columns is
Examination of this formula reveals the following interesting facts with regard to the load-bearing ability of columns.
The strength of a column may therefore be increased by distributing the material so as to increase the moment of inertia. This can be done without increasing the weight of the column by distributing the material as far from the principal axes of the cross section as possible, while keeping the material thick enough to prevent local buckling. This bears out the well-known fact that a tubular section is much more efficient than a solid section for column service.
Another bit of information that may be gleaned from this equation is the effect of length on critical load. For a given size column, doubling the unsupported length quarters the allowable load. The restraint offered by the end connections of a column also affects the critical load. If the connections are perfectly rigid, the critical load will be four times that for a similar column where there is no resistance to rotation (hinged at the ends).
Since the moment of inertia of a surface is its area multiplied by the square of a length called the radius of gyration, the above formula may be rearranged as follows. Using the Euler formula for hinged ends, and substituting A·r2 for I, the following formula results.
where F / A is the allowable stress of the column, and l / r is the slenderness ratio.
Since the structural column is generally an intermediate-length column and it is impossible to obtain an ideal column, the Euler formula has little practical application for ordinary design. Consequently, a number of empirical column formulae have been developed to agree with test data, all of which embody the slenderness ratio. For design, appropriate safety factors are introduced into these formulae.
Self-buckling of columns
A free-standing, vertical column of circular cross-section, with density ρ, Young's modulus E, and radius r, will buckle under its own weight if its height exceeds a certain critical height:
Buckling of surface materials
Buckling is also a failure mode in pavement materials, primarily with concrete, since asphalt is more flexible. Radiant heat from the sun is absorbed in the road surface, causing it to expand, forcing adjacent pieces to push against each other. If the stress is great enough, the pavement can lift up and crack without warning. Going over a buckled section can be very jarring to automobile drivers, described as running over a speed hump at highway speeds.
Similarly, railroad tracks also expand when heated, and can fail by buckling. It is more common for rails to move laterally, often pulling the underlain railroad ties (sleepers) along with them.
Often it is very difficult to determine the exact buckling load in complex structures using the Euler formula, due to the difficulty in deciding the constant K. Therefore, maximum buckling load often is approximated using energy conservation. This way of deciding maximum buckling load is often referred to as the energy method in structural analysis.
The first step in this method is to suggest a displacement function. This function must satisfy the most important boundary conditions, such as displacement and rotation. The more accurate displacement function, the more accurate result.
In this method, there are two equations used to calculate the inner energy and outer energy.
where w(x) is the displacement function. Energy conservation yields:
When a beam is loaded in flexure, the compression side is in compression, and the tension side is in tension. If the beam is not supported in the lateral direction (i.e., perpendicular to the plane of bending), and the flexural load increases to a critical limit, the beam will fail due to lateral buckling of the compression flange. In wide-flange sections, if the compression flange buckles laterally, the cross section will also twist in torsion, resulting in a failure mode known as lateral-torsional buckling.
Buckling will generally occur slightly before the theoretical buckling strength of a structure, due to plasticity of the material. When the compressive load is near buckling, the structure will bow significantly and approach yield. The stress-strain behaviour of materials is not strictly linear even below yield, and the modulus of elasticity decreases as stress increases, with more rapid change near yield. This lower rigidity reduces the buckling strength of the structure and causes premature buckling. This is the opposite effect of the plastic bending in beams, which causes late failure relative to the Euler-Bernoulli beam equation.
If the load on the column is applied suddenly and then released, the column can sustain a load much higher than its static (slowly applied) buckling load. This can happen in a long, unsupported column (rod) used as a drop hammer. The duration of compression at the impact end is the time required for a stress wave to travel up the rod to the other (free) end and back down as a relief wave. Maximum buckling occurs near the impact end at a wavelength much shorter than the length of the rod, at a stress many times the buckling stress if the rod were a statically-loaded column. The critical condition for buckling amplitude to remain less than about 25 times the effective rod straightness imperfection at the buckle wavelength is
where σ is the impact stress, L is the length of the rod, c is the elastic wave speed, and h is the smaller lateral dimension of a rectangular rod. Because the buckle wavelength depends only on σ and h, this same formula holds for thin cylindrical shells of thickness h.
Source: Lindberg, H. E., and Florence, A. L., Dynamic Pulse Buckling, Martinus Nijhoff Publishers, 1987, pp. 11-56, 297-298.
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Buckling". A list of authors is available in Wikipedia.| |
About 11,000 years ago, the last mammoth populations have died out on our planet.
From the thousands of species, only those individuals survived that could survive in the harsh climate on Wrangel Island, but they also could not permanently save their tiny population from extinction. It is known that dwarf representatives of the largest mammals that lived off the coast of Siberia became extinct about 4000 years ago. At the moment, there are several basic hypotheses that can explain the death of ancient animals. In order to prove at least one of them, scientists were able to resurrect genes from recently found mammoth remains.
Why did mammoths die out?
The mystery about the reasons for the complete extinction of the huge mammals that have lived on our planet for many thousands of years is one of the most intriguing secrets of our planet. The most common version is the hypothesis of unexpected climate change, since mammoth extinction peak, according to some estimates, coincides with a period of sharp warming. It is assumed that this could be the reason for the reduced diet of animals, to which they did not have time to adapt. Due to the increased humidity and water logging of the soil on Wrangel Island, mammoths found it difficult to move in order to get their own food.
Another possible theory about the causes of the death of mammoths is the idea of their loss of genetic diversity. So, due to the small habitat of mammoths (Wrangel Island could feed no more than 300 individuals), at some point cases of closely related crosses became more frequent, which led to the loss of animals’ ability to reproduce as a result of various kinds of genetic mutations.
According to an article published in the journal Genome Biology and Evolution (GBE), experts have several reasons that indicate the appearance of several types of genetic defects in mammoths. In order to confirm this theory, scientists conducted a study for the “Resurrected” genome mammoth, suggesting that mammoths could lose their ability to reproduce, along with their ability to smell.
The results of this study can be evidence of both the first and second main hypotheses for the extinction of mammoths on Wrangel Island, since scientists are confident that due to the rapid decline in the population due to a decrease in the amount of food obtained, mammoths could interbreed with their distant relatives. This crossing significantly reduced their genetic diversity, as a result of which animals could lose the ability to “purify” the genome.
During the study, a team of scientists compared the mammoth’s DNA with living members of the elephant family, as well as with the oldest mammoths that lived tens of thousands of years ago on the territory of the African continent. During the experiment, experts identified a number of genetic abnormalities in animals from Wrangel Island, which were really responsible for the neurological development of animals, their fertility, insulin signaling, and their ability to smell. At the moment, scientists suggest that animals could completely lose their sense of smell and were unable to distinguish the smell of edible food from inedible. The combination of all negative factors affected the lifestyle of mammoths, causing their gradual, but inevitable extinction as a species. Be that as it may, scientists hope to resurrect these animals in the coming years. |
The robotic spacecraft MESSENGER ran out of fuel. With no way to make major adjustments to its orbit around the planet Mercury, the probe smashed into the surface at more than 8,750 miles per hour (3.91 kilometers per second). The impact added a new crater to the planet’s scarred face that engineers estimate was as wide as 52 feet (16 meters).
A NASA planetary exploration mission came to a planned, but nonetheless dramatic, end Thursday when it slammed into Mercury’s surface at about 8,750 mph and created a new crater on the planet’s surface.
Mission controllers at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland, have confirmed NASA’s MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft impacted the surface of Mercury, as anticipated, at 3:26 p.m. EDT.
Mission control confirmed end of operations just a few minutes later, at 3:40 p.m., when no signal was detected by NASA’s Deep Space Network (DSN) station in Goldstone, California, at the time the spacecraft would have emerged from behind the planet. This conclusion was independently confirmed by the DSN’s Radio Science team, which also was monitoring for a signal from MESSENGER.
“Going out with a bang as it impacts the surface of Mercury, we are celebrating MESSENGER as more than a successful mission,” said John Grunsfeld, associate administrator for NASA’s Science Mission Directorate in Washington. “The MESSENGER mission will continue to provide scientists with a bonanza of new results as we begin the next phase of this mission–analyzing the exciting data already in the archives, and unravelling the mysteries of Mercury.”
Prior to impact, MESSENGER’s mission design team predicted the spacecraft would pass a few miles over a lava-filled basin on the planet before striking the surface and creating a crater estimated to be as wide as 50 feet.
MESSENGER’s lonely demise on the small, scorched planet closest to the sun went unobserved because the probe hit the side of the planet facing away from Earth, so ground-based telescopes were not able to capture the moment of impact. Space-based telescopes also were unable to view the impact, as Mercury’s proximity to the sun would damage optics.
MESSENGER’s last day of real-time flight operations began at 11:15 a.m., with initiation of the final delivery of data and images from Mercury via a 230-foot (70-meter) DSN antenna located in Madrid, Spain. After a planned transition to a 111-foot (34-meter) DSN antenna in California, at 2:40 p.m., mission operators later confirmed the switch to a beacon-only communication signal at 3:04 p.m.
The mood in the Mission Operations Center at APL was both somber and celebratory as team members watched MESSENGER’s telemetry drop out for the last time, after more than four years and 4,105 orbits around Mercury.
“We monitored MESSENGER’s beacon signal for about 20 additional minutes,” said mission operations manager Andy Calloway of APL. “It was strange to think during that time MESSENGER had already impacted, but we could not confirm it immediately due to the vast distance across space between Mercury and Earth.”
MESSENGER was launched on Aug. 3, 2004, and began orbiting Mercury on March 17, 2011. Although it completed its primary science objectives by March 2012, the spacecraft’s mission was extended two times, allowing it to capture images and information about the planet in unprecedented detail.
During a final extension of the mission in March, referred to as XM2, the team began a hover campaign that allowed the spacecraft to operate within a narrow band of altitudes from five to 35 kilometers from the planet’s surface.
On Tuesday, the team successfully executed the last of seven daring orbit correction maneuvers that kept MESSENGER aloft long enough for the spacecraft’s instruments to collect critical information on Mercury’s crustal magnetic anomalies and ice-filled polar craters, among other features. After running out of fuel, and with no way to increase its altitude, MESSENGER was finally unable to resist the sun’s gravitational pull on its orbit.
“Today we bid a fond farewell to one of the most resilient and accomplished spacecraft to ever explore our neighboring planets,” said Sean Solomon, MESSENGER’s principal investigator and director of Columbia University’s Lamont-Doherty Earth Observatory in Palisades, New York. “A resourceful and committed team of engineers, mission operators, scientists, and managers can be extremely proud that the MESSENGER mission has surpassed all expectations and delivered a stunningly long list of discoveries that have changed our views–not only of one of Earth’s sibling planets, but of the entire inner solar system.”
Among its many accomplishments, the MESSENGER mission determined Mercury’s surface composition, revealed its geological history, discovered its internal magnetic field is offset from the planet’s center, and verified its polar deposits are dominantly water ice.
The Mercury Atmosphere and Surface Composition Spectrometer (MASCS) instrument aboard NASA’s MESSENGER spacecraft was designed to study both the exosphere and surface of the planet Mercury. To learn more about the minerals and surface processes on Mercury, the Visual and Infrared Spectrometer (VIRS) portion of MASCS has been diligently collecting single tracks of spectral surface measurements since MESSENGER entered Mercury orbit on March 17, 2011. The track coverage is now extensive enough that the spectral properties of both broad terrains and small, distinct features such as pyroclastic vents and fresh craters can be studied. To accentuate the geological context of the spectral measurements, the MASCS data have been overlain on the monochrome mosiac from the Mercury Dual Imaging System (MDIS), an instrument with wide- and narrow-angle cameras to map the rugged landforms and spectral variations on Mercury’s surface. Click on the image to explore the colorful diversity of surface materials in more detail!
The MESSENGER spacecraft is the first ever to orbit the planet Mercury, and the spacecraft’s seven scientific instruments and radio science investigation are unraveling the history and evolution of the solar system’s innermost planet. In the mission’s more than four years of orbital operations, MESSENGER has acquired over 250,000 images and extensive other data sets. MESSENGER’s highly successful orbital mission is about to come to an end, as the spacecraft runs out of propellant and the force of solar gravity causes it to impact the surface of Mercury near the end of April 2015.
Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
APL built and operated the MESSENGER spacecraft and managed the mission for NASA’s Science Mission Directorate in Washington.
Learn more about the accomplishments of NASA’s MESSENGER mission at: |
When writing a sonnet in the style of Shakespeare, there are some rules you need to keep. This type of poetry is required to follow a specific format including length, rhythm, and rhyme scheme. To write a sonnet correctly, to follow this process:
Select a subject to write your sonnet about as Shakespearean sonnets are on tradition grounded as love poems. Write your lines in iambic pentameter.
Necessary Format: Format the sonnet using three quatrains followed by one couplet.
Form your sonnet as evidence that builds up as it goes from one metaphor to the next. Be sure that every line of the sonnet has ten syllables that conform to the Iambic Pentameter. Guarantee your sonnet is precisely 14 lines and the last syllable on each line rhymes with another last syllable on a previous line.
The Shakespeare Rhyming scheme
If you’re writing the most common kind of sonnet, the Shakespearean sonnet, then the rhyme scheme for the last syllable of the line is as follows:
Every ‘A’ last syllable of the line must rhyme, and every ‘B’ syllables rhyme and so forth. You’ll see this kind of sonnet consists of three quatrains. Or four consecutive lines of verse that make up a stanza or division of lines in a poem, and one couplet (two successive rhyming lines).
How a Sonnet Tells the Story
Ah, but there’s more to a sonnet than just the structure of it. A sonnet is also an argument — it builds up a certain way. And how it builds up is related to its metaphors and how it moves from one metaphor to the next. In a Shakespearean sonnet, the argument builds up like this:
First quatrain: An exposition of the central theme and primary metaphor.
Second quatrain: Theme and metaphor extended or complicated; often, some ingenious example is given.
Third quatrain: Peripeteia (a twist or conflict), often introduced by a “but” (very often leading off the ninth line).
Couplet: Reviews and leaves the reader with a new, closing image.
One of Shakespeare’s best-known sonnets is Sonnet 18, which follows this pattern:
Shall I compare thee to a summer’s day?
Thou art more lovely and more temperate.
Rough winds do shake the darling buds of May,
And summer’s lease hath all too short a date.
Sometime too hot the eye of heaven shines,
And often is his gold complexion dimmed;
And every fair from fair sometime declines,
By chance, or nature’s changing course, untrimmed;
But thy eternal summer shall not fade,
Nor lose possession of that fair thou owest,
Nor shall death brag thou wanderest in his shade,
When in eternal lines to time thou growest.
So long as men can breathe or eyes can see,
So long lives this, and this gives life to thee.
The arrangement of a Sonnet like this:
First quatrain: Worship, worship, excellent.
Second quatrain: Worship, worship, excellent.
Third quatrain: But, even if the bad thing happens, still excellent.
Couplet: Future excellent.
So now you see Shakespeare was a master of the english language and has been remembered over four-hundred years after his death. |
Depending on the nature of your research, the definition of a "primary source" can vary (Stebbins 62). Historians may use newspaper articles or diary entries written by a person living during a particular time period while natural scientists would consider a research study/experiment that provides new knowledge a primary source. An attorney would consider written laws or the constitution as primary documents. "Books and articles that come right from the context of a subject, straight out of the horse's mouth...are primary sources" (Badke 12).
Secondary sources synthesize or analyze primary sources (Stebbins 62). The research paper you are writing for your English 112 class, which may cite both secondary and primary sources, is actually considered a secondary source. Your research paper is arguing a point, but those points and evidence come from other resources that you are sythesizing and analyzing.
|PRIMARY Sources||SECONDARY Sources|
|Text of Homer's Iliad||A modern study of Homer's Iliad|
|A scientific study written by the researcher||Analysis of a researcher's experiment|
|Firsthand account by a witness of 9/11||Book on 9/11 by someone not there|
|Street person's account of street life||Analysis of research on street people|
(Chart, Badke 13)
Badke, William B. Research Strategies: Finding Your Way Through the Information Fog, 3rd ed. (2008). iUniverse, Inc. New York, NY
Stebbins, Leslie F. Student Guide to Research in the Digital Age: How to Locate and Evaluate Information Sources. (2006). Libraries Unlimited. Westport, CT.
*Courtesy of Hartness Library System |
I've said in the past that the lion's share of the really amazing fossils, in terms of preservation and importance, seem to be coming out of China in the last 10 years or so. But, now an exceptionally well preserved theropod dinosaur has been unearthed in Germany. And it's important too. It's a feathered theropod dinosaur that is only distantly related to the group of theropods that gave rise to the birds.
|A photograph of the new feathered dinosaur fossil, Sciurumimus albersdoerferi. The scale bar shows 5 cm, so, as it's name suggests, it's about the size of a squirrel (image taken from the paper).|
The researchers gave it the name Sciurumimus albersdoerferi. The genus name means squirrel mimic because the feathers on its tail make it bushy like a squirrel's. The species name is given in honour of Raimund Albersdörfer, who made the specimen available to the researchers for their study.
The fossil is important for a couple of reasons. The first is that it is distantly related to other theropod dinosaurs that we know for sure had feathers. Which pushes the evolution of feathers back closer to the common ancestor of all theropods. Combine this with the evidence that some heterodontosaurs had feathers and the hypothesis that the common ancestor of all dinosaurs was feathered gains some weight. But, the independent evolution of feathers in the theropods and heterodontosaurs is far from refuted.
The other reason this fossil is important is that it is the best preserved fossil megalosauroid thus far discovered. Indeed, it provides the only complete megalosauroid skeleton. Therefore it provides evidence that helps resolve several questions about the evolution of traits in theropods, such as the evolution of bones in the hand.
An interesting side note is that this fossil is of a very young individual, which probably died soon after hatching. Therefore, the bushy tail is almost certainly not a sexually selected character. This pours some cold water on the hypothesis that feathers evolved in dinosaurs primarily as a means to signal mate quality, which was claimed in another recent paper. |
An egg once held the weight of a 200-pound man. Though small in stature, farm fresh eggs have big power. Their shells provide homes to growing chicks and shield yolks from harmful bacteria. But how can a structure that’s only 0.3 millimeters thick provide so much security? The answer comes down to design.
In fact, architects through the ages have modeled buildings after the dome of the egg. A dome shape offers strength and protection; any pressure applied to the top of the dome is spread throughout the structure. This simple power makes the egg one of nature’s leading designs.
Building an eggshell: Calcium and Vitamin D3
Similar to the supplies needed to build an architectural dome, hens require specific nutrients to produce eggs with strong shells. Calcium and vitamin D3 are two of the more important nutrients needed to build strong eggshells.
Calcium is the most important nutrient for eggshell development, and vitamin D3 is vital to getting the calcium where it needs to go. All told, each eggshell includes about 2 grams of calcium – or 40 percent of the shell.
This number has big meaning when looking at simple math. If the average backyard hen lays 180 to 200 eggs per year, that’s 0.8 to 0.88 pounds of calcium per year for eggshell development. This calcium must come from the diet to support eggshell production.
Calcium transport in eggshell production
After a hen consumes calcium, the nutrient begins the journey to eggshell production. It first enters the blood stream where it is carried to the shell gland and the rest of the body. To help calcium travel quickly enough to create strong eggshells, vitamin D3 also plays a large role.
Vitamin D3 is necessary, because it increases the rate at which calcium passes through the intestinal lining into the blood stream. The birds require large amounts of calcium when the shell gland is active. For this reason, layer feeds should also include vitamin D3: to get enough calcium to the shell gland when it is needed.
Providing the building blocks for strong eggshells
Hens need to consume around 4 grams of calcium each day in order to get the 2 grams of calcium needed to make one egg shell – not all of the calcium goes to making eggshells. As stated previously, the nutrient – along with Vitamin D3 – must come from the hen’s feed.
Be sure to provide hens a complete feed, like Purina® Layena® Pellets or Crumbles. This complete feed is formulated to provide the necessary four grams of calcium. On the other hand, the average scratch grains product provides only 0.1 grams of calcium and no vitamin D3.
For optimally strong shells and fresh eggs, choose a feed that also includes an oyster shell mix, like Oyster Strong™ System. This system is included in Layena® to provide a consistent supply of calcium through the entire 20-hour shell building process.
Oyster shell is a good way to provide calcium because of its large particle size. Smaller calcium particles break down quickly, but oyster shell particles have a slower transit time. This means the calcium source stays in the hen longer and plays an important role in eggshell formation at night when hens need calcium most.
Eggshells are created during a 24-26 hour process. Learn the magic behind farm fresh eggs here.
Source: Patrick Biggs, Ph.D – Flock Nutritionist, Purina Animal Nutrition |
Hearing loss can affect patients at any age. Causes and treatments vary widely depending on the circumstances. Unaddressed hearing loss impairs the ability of a person to effectively communicate and interact with their surroundings and negatively impacts quality of life. Whether the patient is a toddler learning speech, a mid-career professional struggling to understand in meetings, or a senior trying to hear a church sermon, the first step is to diagnose the problem correctly, which our physicians will do at the Shea Ear Clinic, and recommend appropriate treatment. Many hearing problems are compounded by incorrectly diagnosed hearing loss.
Common complaints and effects on patients with hearing loss include:
- Asking people to repeat frequently
- Turning up the TV too loud or sitting too close
- Misunderstanding words or meanings
- Talking too loud
- Denial and embarrassment
- Social withdrawal, isolation, and loneliness
- Reduced job performance and earning power
- Impaired memory and ability to learn new tasks
- Irritability, frustration, and anger
- Fatigue, tension, stress and depression
- Diminished psychological and overall health
Generally, there are three types of hearing loss
- Conductive hearing loss is caused by a mechanical problem in the ear canal or middle ear that blocks the conduction of sound to the inner ear. Conductive hearing loss is often reversible.
- Sensorineural hearing loss or “nerve deafness”, is caused by damage to the inner ear, auditory nerve, or auditory nerve pathways to the brain. Often, this type of loss is not reversible, but it is still treatable.
- A mixed loss is a combination of a conductive and a sensorineural hearing loss.
Am I losing my hearing?
Hearing loss may be gradual or sudden and affects us emotionally, physically, and socially. These common behaviors and responses may indicate hearing loss.
- Answer or respond inappropriately in conversations
- Think people’s speech is muffled or they mumble
- Have difficulty following conversations involving more than 2 people
- Require frequent repetition
- Have trouble hearing and understanding women and children
- Find yourself reading lips or watching their faces when they speak
- Have difficulty hearing in noisy surroundings such as restaurants
- Require your TV or radio turned up to high volume
- Feel stressed from straining to hear
- Feel annoyed with others because you can’t hear or understand them
- Feel embarrassed from not being able to understand others
- Feel nervous about trying to hear and understand others
- Avoid social functions because of difficulty hearing
Why am I losing my hearing?
Age, disease and injury generally contribute to the inability to hear. Repeated exposure to loud noise over time can damage the delicate structures of the ear, and ultimately, the ability to hear. Family history, genetics and even medications can contribute to hearing loss. |
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