A team of students and professors from a local college has made it into the final round of a NASA competition.
A dozen robotics students from Worcester Polytechnic Institute in Worcester, Massachusetts, along with their professors, are seeking to program virtual robots that can locate and extract valuable resources from the moon as part of the NASA-sponsored Space Robotics Challenge -- which is a part of NASA’s Centennial Challenges program.
The team that calls itself Capricorn -- one of 22 left in the competition, according to Robotics Engineering Professor Michael Gennert -- has spent hours working on software for a fleet of robots.
“The goal is to find resources on the moon, dig them up and bring them to a processing plant where they can be turned into useful stuff like oxygen, iron, steel, and so on," Gennert said.
Team Capricorn is continuing to design algorithms that could be used on NASA robots which could go to the moon or even Mars some day.
“It’s really exciting to face multiple, difficult problems that people actually see out there and might not have been solved,” said Ashay Aswale, a PhD student in robotics engineering who is serving as the project manager for Team Capricorn.
“The interesting part is that this mining technology can also be useful on the earth. Mining is becoming increasingly more difficult on the earth so having robots that can be sent and be autonomous, and can mine without the needs to endanger the life of people is very important,” said Carlo Pinciroli, assistant professor of robotics engineering.
Besides looking for resources, the team has also programed the virtual robots to do tasks like fixing satellites. So far, they’ve been awarded $15,000 for their work in the qualification round -- the maximum possible in that round.
“This technology, it's a great way to get students excited about a project, and get some visibility and also helped develop technologies that we hope NASA can use in the future,” Gennert said.
The competition is expected to end in July with the winner announced sometime in September.


(ACCOMAC, Va.)—The Eastern Shore Health District reminds residents to protect themselves from mosquito bites and to take measures to reduce mosquito populations on their property in order to reduce the risk of mosquito-borne illnesses like West Nile Virus and Eastern Equine Encephalitis. While mosquito-borne illnesses can infect people in tropical climates year round, they are more often reported in our region in the late summer and early fall.
Humans, equines, and avians can be infected with West Nile Virus and Eastern Equine Encephalitis from the bite of infected mosquitoes. The time from the infected mosquito bite to the onset of illness (the incubation period) ranges between 2 and 14 days. There is no risk of infection by direct contact with ill people or animals, only through the bite of infected mosquitoes.
About 80% of people that are infected with West Nile Virus will not develop any symptoms. About 20% of people will develop a fever and may experience symptoms such as headaches, body aches, joint aches, vomiting, diarrhea, or rash. An estimated 1 out of 150 infected people will develop a severe, neuroinvasive West Nile virus infection: fever, headache, stiff neck, disorientation or confusion, vision loss, seizures, paralysis, and even death. Individuals over 60 years of age are at an increased risk of developing a neuroinvasive infection and should take extra precautions to avoid mosquito bites.
Symptoms of Eastern Equine Encephalitis in humans can also range from mild flu-like illness to encephalitis, coma and death. One third of people who develop EEEV die and even survivors may have permanent neurologic damage.
To prevent mosquito bites from exposing you to these and other illnesses, wear long, loose, light colored clothing and apply mosquito repellents to exposed skin areas while outdoors. Products containing DEET and Picaridin typically provide the longest lasting protection. Other types of repellents may need to be applied more frequently, but also are effective. Permethrin is effective when used to treat clothing, screens or tents, but is not recommended to be used directly on the skin.
Equines and other animals can also be sprayed with mosquito repellent products that are suitable for them. Follow product instructions or consult your veterinarian for more information about protecting your animals. Vaccinated equines are also less likely die from mosquito-borne illness than unvaccinated equines. So make sure all of your equines, especially the young ones and the old ones are currently vaccinated. Consult your veterinarian if you are not sure.
The types of mosquitoes that transmit these specific diseases are often found near man-made water holding containers or polluted ditches. You can report ditches that do not drain to your county public works departments. You can also help keep the ditches draining more effectively by keeping them free of trash and litter in your neighborhood.
On your own property, eliminate standing water by doing the following:
- Keep gutters and down spouts clean.
- Eliminate standing water areas with better grading and/or drainage. Where this is a challenge, use mosquito dunks that are available at most hardware stores.
- Clean up all trash on your property, especially old tires.
- Keep your outdoor trash covered at all times.
- Empty water from flower trays, buckets, boat covers, tarps, flat roofs and all containers where water collects on your property after each rainfall.
- At least once per week clean out bird baths and wading pool.
- Eliminate standing water on tarps and flat roofs after each rain shower.
If you would like more information about mosquito-borne illness and prevention, visit the Virginia Department of Health website: http://www.vdh.virginia.gov/environmental-epidemiology/bugs-human-health/.


In 2016, over 190,000 tonnes of litter was collected from the streets of New Zealand by approximately 86,000 Keep New Zealand Beautiful volunteers. Motivated by this and with the support of the New Zealand Government, we carried out a national litter audit in 2019 which compiled data through the physical inspection and visual counting of litter in a number of specific, fixed sites. The information collected provides data on the quantities, types, locations, and brands of litter deposited across the country. The National Litter Audit was developed in consultation with Statistics New Zealand, the Department of Conservation and the Ministry for the Environment. It provides tier 1 statistics and baseline data on litter across New Zealand to help inform policy development, and will provide the basis for ongoing environmental reporting on litter. Key findings Cigarette butts were the most frequently identified item nationally, with 39 butts recorded per 1000m2. Disposable nappies represented the largest contribution to the estimated national litter volumes, recording 1.50 ltr of volume per 1,000 m2. Glass beer bottles (less than 750 ml, all colours) represented the largest contribution to the national litter weights, recording 0.12 kg of weight per 1,000 m2. Illegal dumping contributed the largest proportion to the total estimated litter volume at highway and railway sites nationally, recording 17.36 ltr per 1,000 m2 and 11.93 ltr of volume per 1,000 m2 respectively. National Litter Audit 2019 7 MB 522 downloads … Download You can request the data from the National Litter Audit 2019 here.


Summer ozone season has arrived...protect your health and help reduce ozone pollution
This summer all eyes and ears are on the potential for wildfires in our area. Smoke from wildfires is a health concern and is being monitored very closely.
What is ozone and why is it a summer air pollution problem?
Ozone can be "good" or "bad" depending on its location in the atmosphere. In the upper atmosphere,"good" ozone is produced naturally and protects us from UV radiation.
At ground-level, "bad" ozone is a harmful air pollutant and is the key component of smog. Ground level ozone peaks on hot summer days because it is formed by a photochemical reaction between nitrogen oxides and volatile organic compounds (VOCs) in the presence of sunlight.
Where do VOCs come from?
Volatile Organic Compounds (VOCs) are emitted to the air from a variety of activities, including:
- Industrial and commercial operations
- Vehicle refueling, driving
- Using lawnmowers and other gas-powered equipment
- Using products such as cleaners, paints/solvents, bbq lighter fluid, etc.
What’s being done to reduce ozone pollution?
There are a number of strategies in place to reduce emissions that contribute to ozone formation, including
- Vapor recovery equipment required for storage tank filling at gas stations
- Commercial emissions controls
- Vehicle emissions check program
- Emissions standards for new engines
- Voluntary and mandated Commute Trip Reduction Programs at worksites
Who’s at risk from ozone?
Breathing unhealthful levels of ozone has been likened to "giving your lungs a sunburn." Children are at highest risk because their lungs are still developing. They are more likely to have asthma or other respiratory illnesses, and they are very active outdoors.
Adults with asthma or other respiratory diseases are also at risk. New evidence shows ozone may cause chronic obstructive pulmonary diseases, such as chronic asthma, chronic bronchitis, emphysema.
Healthy adults can experience a 15-20% reduction in lung function from prolonged exposure to low levels of ozone.
How can I find the current pollution levels?
Spokane Clean Air monitors air quality daily, and reports air pollution levels here. While on that page, people can see a link to subscribe to EnviroFlash -- a personalized air quality email notification program, or download a smart phone app.
How can I reduce ozone levels?
- Reduce car trips by combining errands. Walk, bicycle or ride the bus once a week, instead of driving alone.
- Refuel in the evening. This keeps ozone-forming vapors out of the air during the heat of the day.
- Hold off using gas-powered lawn equipment until evening.
- Use manual or electric yard and garden tools.
- If you use a charcoal barbecue, start it with an electric probe instead of lighter fluid.
What should I do when ozone levels rise?
- Limit strenuous outdoor activity, exercise early when ozone is lower.
- Pay attention to respiratory symptoms such as coughing, wheezing, discomfort. See your health provider if necessary.
For more information:


Juno (minor-planet designation: 3 Juno) is an asteroid in the asteroid belt. Juno was the third asteroid discovered, in 1804, by German astronomer Karl Harding. It is the 11th-largest asteroid, and one of the two largest stony (S-type) asteroids, along with 15 Eunomia. It is estimated to contain 1% of the total mass of the asteroid belt.
The orbit of Juno is significantly elliptical with a small inclination, moving between Mars and Jupiter.
|Discovered by||Karl Ludwig Harding|
|Discovery date||September 1, 1804|
|MPC designation||(3) Juno|
|Juno (Latin: Iūno)|
|Main belt (Juno clump)|
|Epoch JD 2457000.5 (9 December 2014)|
Average orbital speed
|Proper orbital elements|
Proper semi-major axis
Proper mean motion
|82.528181 deg / yr|
Proper orbital period
Precession of perihelion
|43.635655 arcsec / yr|
Precession of the ascending node
|−61.222138 arcsec / yr|
|216 000 km2|
|Volume||8 950 000 km3|
|Mass||2.67 ×1019 kg|
Equatorial surface gravity
Equatorial escape velocity
|7.21 hr (0.3004 d)|
Equatorial rotation velocity
max: 301 K (+28°C)
|7.4 to 11.55|
|0.30" to 0.07"|
Juno was discovered on 1 September 1804, by Karl Ludwig Harding. It was the third asteroid found, but was initially considered to be a planet; it was reclassified as an asteroid and minor planet during the 1850s.
Juno is named after the mythological Juno, the highest Roman goddess. The adjectival form is Junonian (jūnōnius).
With two exceptions, 'Juno' is the international name, subject to local variation: Italian Giunone, French Junon, Russian Yunona, etc.[a] Its planetary symbol is ③. An older symbol, still occasionally seen, is ⚵ ( ).
Juno is one of the larger asteroids, perhaps tenth by size and containing approximately 1% the mass of the entire asteroid belt. It is the second-most-massive S-type asteroid after 15 Eunomia. Even so, Juno has only 3% the mass of Ceres.
The orbital period of Juno is 4.36578 years.
Amongst S-type asteroids, Juno is unusually reflective, which may be indicative of distinct surface properties. This high albedo explains its relatively high apparent magnitude for a small object not near the inner edge of the asteroid belt. Juno can reach +7.5 at a favourable opposition, which is brighter than Neptune or Titan, and is the reason for it being discovered before the larger asteroids Hygiea, Europa, Davida, and Interamnia. At most oppositions, however, Juno only reaches a magnitude of around +8.7—only just visible with binoculars—and at smaller elongations a 3-inch (76 mm) telescope will be required to resolve it. It is the main body in the Juno family.
Juno was originally considered a planet, along with 1 Ceres, 2 Pallas, and 4 Vesta. In 1811, Schröter estimated Juno to be as large as 2290 km in diameter. All four were reclassified as asteroids as additional asteroids were discovered. Juno's small size and irregular shape preclude it from being designated a dwarf planet.
Juno orbits at a slightly closer mean distance to the Sun than Ceres or Pallas. Its orbit is moderately inclined at around 12° to the ecliptic, but has an extreme eccentricity, greater than that of Pluto. This high eccentricity brings Juno closer to the Sun at perihelion than Vesta and further out at aphelion than Ceres. Juno had the most eccentric orbit of any known body until 33 Polyhymnia was discovered in 1854, and of asteroids over 200 km in diameter only 324 Bamberga has a more eccentric orbit.
Juno rotates in a prograde direction with an axial tilt of approximately 50°. The maximum temperature on the surface, directly facing the Sun, was measured at about 293 K on October 2, 2001. Taking into account the heliocentric distance at the time, this gives an estimated maximum temperature of 301 K (+28 °C) at perihelion.
Spectroscopic studies of the Junonian surface permit the conclusion that Juno could be the progenitor of chondrites, a common type of stony meteorite composed of iron-bearing silicates such as olivine and pyroxene. Infrared images reveal that Juno possesses an approximately 100 km-wide crater or ejecta feature, the result of a geologically young impact.
Juno was the first asteroid for which an occultation was observed. It passed in front of a dim star (SAO 112328) on February 19, 1958. Since then, several occultations by Juno have been observed, the most fruitful being the occultation of SAO 115946 on December 11, 1979, which was registered by 18 observers. Juno occulted the magnitude 11.3 star PPMX 9823370 on July 29, 2013, and 2UCAC 30446947 on July 30, 2013.
Radio signals from spacecraft in orbit around Mars and on its surface have been used to estimate the mass of Juno from the tiny perturbations induced by it onto the motion of Mars. Juno's orbit appears to have changed slightly around 1839, very likely due to perturbations from a passing asteroid, whose identity has not been determined.
In 1996, Juno was imaged by the Hooker Telescope at Mount Wilson Observatory at visible and near-IR wavelengths, using adaptive optics. The images spanned a whole rotation period and revealed an irregular shape and a dark albedo feature, interpreted as a fresh impact site.
Juno seen at four wavelengths with a large crater in the dark (Hooker telescope, 2003)
Juno moving across background stars
Juno during opposition in 2009
Video of Juno taken as part of ALMA's Long Baseline Campaign
Juno reaches opposition from the Sun every 15.5 months or so, with its minimum distance varying greatly depending on whether it is near perihelion or aphelion. Sequences of favorable oppositions occur every 10th opposition, i.e. just over every 13 years. The last favorable oppositions were on December 1, 2005, at a distance of 1.063 AU, magnitude 7.55, and on November 17, 2018, at a minimum distance of 1.036 AU, magnitude 7.45. The next opposition will be October 30, 2031, at a distance of 1.044 AU, magnitude 7.42.
- The exceptions are Greek, where the name was translated to its Hellenic equivalent, Hera (3 Ήρα), as in the cases of 1 Ceres and 4 Vesta; and Chinese, where it is called the 'marriage-god(dess) star' (婚神星 hūnshénxīng). This contrasts with the goddess Juno, for which Chinese uses the transliterated Latin name (朱諾 zhūnuò).
- "Junonian". Oxford English Dictionary (3rd ed.). Oxford University Press. September 2005. (Subscription or UK public library membership required.)
- "JPL Small-Body Database Browser: 3 Juno" (2017-11-26 last obs). Retrieved 2014-11-17.
- "AstDyS-2 Juno Synthetic Proper Orbital Elements". Department of Mathematics, University of Pisa, Italy. Retrieved 2011-10-01.
- Jim Baer (2008). "Recent Asteroid Mass Determinations". Personal Website. Archived from the original on 2013-07-02. Retrieved 2008-12-03.
- Lim, L; McConnochie, T; Belliii, J; Hayward, T (2005). "Thermal infrared (8?13 ?m) spectra of 29 asteroids: The Cornell Mid-Infrared Asteroid Spectroscopy (MIDAS) Survey" (PDF). Icarus. 173 (2): 385. Bibcode:2005Icar..173..385L. doi:10.1016/j.icarus.2004.08.005.
- Calculated based on the known parameters
- Harris, A. W.; Warner, B. D.; Pravec, P., eds. (2006). "Asteroid Lightcurve Derived Data. EAR-A-5-DDR-DERIVED-LIGHTCURVE-V8.0". NASA Planetary Data System. Archived from the original on April 9, 2009. Retrieved 2007-03-15.
- Davis, D. R.; Neese, C., eds. (2002). "Asteroid Albedos. EAR-A-5-DDR-ALBEDOS-V1.1". NASA Planetary Data System. Archived from the original on December 17, 2009. Retrieved 2007-02-18.
- Lim, Lucy F.; McConnochie, Timothy H.; Bell, James F.; Hayward, Thomas L. (2005). "Thermal infrared (8–13 µm) spectra of 29 asteroids: the Cornell Mid-Infrared Asteroid Spectroscopy (MIDAS) Survey". Icarus. 173 (2): 385–408. Bibcode:2005Icar..173..385L. doi:10.1016/j.icarus.2004.08.005.
- Neese, C., ed. (2005). "Asteroid Taxonomy.EAR-A-5-DDR-TAXONOMY-V5.0". NASA Planetary Data System. Archived from the original on 2006-09-05. Retrieved 2013-12-24.
- "AstDys (3) Juno Ephemerides". Department of Mathematics, University of Pisa, Italy. Retrieved 2010-06-26.
- "Bright Minor Planets 2005". Minor Planet Center. Archived from the original on 2008-09-29.
- Cunningham, Clifford J (2017), Bode's Law and the discovery of Juno : historical studies in asteroid research, Springer, ISBN 978-3-319-32875-1
- Pitjeva, E. V. (2005). "High-Precision Ephemerides of Planets—EPM and Determination of Some Astronomical Constants" (PDF). Solar System Research. 39 (3): 176. Bibcode:2005SoSyR..39..176P. doi:10.1007/s11208-005-0033-2. Archived from the original (PDF) on 2008-10-31.
- Hilton, James L. "When did the asteroids become minor planets?". U.S. Naval Observatory. Archived from the original on 2008-03-24. Retrieved 2008-05-08.
- Pitjeva, E. V.; Precise determination of the motion of planets and some astronomical constants from modern observations, in Kurtz, D. W. (Ed.), Proceedings of IAU Colloquium No. 196: Transits of Venus: New Views of the Solar System and Galaxy, 2004
- "Comets Asteroids". Find The Data.org. Archived from the original on 14 May 2014. Retrieved 14 May 2014.
- Odeh, Moh'd. "The Brightest Asteroids". The Jordanian Astronomical Society. Archived from the original on 11 May 2008. Retrieved 2008-05-21.
- "What Can I See Through My Scope?". Ballauer Observatory. 2004. Archived from the original on July 26, 2011. Retrieved 2008-07-20. (archived)
- Hilton, James L (2007-11-16). "When did asteroids become minor planets?". U.S. Naval Observatory. Archived from the original on 2008-03-24. Retrieved 2008-06-22.
- "MBA Eccentricity Screen Capture". JPL Small-Body Database Search Engine. Archived from the original on March 27, 2009. Retrieved 2008-11-01.
- The north pole points towards ecliptic coordinates (β, λ) = (27°, 103°) within a 10° uncertainty. Kaasalainen, M.; Torppa, J.; Piironen, J. (2002). "Models of Twenty Asteroids from Photometric Data" (PDF). Icarus. 159 (2): 369–395. Bibcode:2002Icar..159..369K. doi:10.1006/icar.2002.6907.
- Gaffey, Michael J.; Burbine, Thomas H.; Piatek, Jennifer L.; Reed, Kevin L.; Chaky, Damon A.; Bell, Jeffrey F.; Brown, R. H. (1993). "Mineralogical variations within the S-type asteroid class". Icarus. 106 (2): 573. Bibcode:1993Icar..106..573G. doi:10.1006/icar.1993.1194.
- "Asteroid Juno Has A Bite Out Of It". Harvard-Smithsonian Center for Astrophysics. 2003-08-06. Archived from the original on 8 February 2007. Retrieved 2007-02-18.
- Baliunas, Sallie; Donahue, Robert; Rampino, Michael R.; Gaffey, Michael J.; Shelton, J. Christopher; Mohanty, Subhanjoy (2003). "Multispectral analysis of asteroid 3 Juno taken with the 100-inch telescope at Mount Wilson Observatory" (PDF). Icarus. 163 (1): 135–141. Bibcode:2003Icar..163..135B. doi:10.1016/S0019-1035(03)00049-6.
- Millis, R. L.; Wasserman, L. H.; Bowell, E.; Franz, O. G.; White, N. M.; Lockwood, G. W.; Nye, R.; Bertram, R.; et al. (February 1981). "The diameter of Juno from its occultation of AG+0°1022" (PDF). Astronomical Journal. 86: 306–313. Bibcode:1981AJ.....86..306M. doi:10.1086/112889.
- Asteroid Occultation Updates – Jul 29, 2013
- Asteroid Occultation Updates – Jul 30, 2013.
- Pitjeva, E. V. (2004). "Estimations of masses of the largest asteroids and the main asteroid belt from ranging to planets, Mars orbiters and landers". 35th COSPAR Scientific Assembly. Held 18–25 July 2004, in Paris, France. p. 2014. Bibcode:2004cosp...35.2014P.
- Hilton, James L. (February 1999). "US Naval Observatory Ephemerides of the Largest Asteroids". Astronomical Journal. 117 (2): 1077–1086. Bibcode:1999AJ....117.1077H. doi:10.1086/300728. Retrieved 2012-04-15.
- The Astronomical Amanac for the year 2018, G14
- Asteroid 3 Juno at opposition 16 Nov 2018 at 11:31 UTC
|Wikimedia Commons has media related to 3 Juno.|
- JPL Ephemeris
- Well resolved images from four angles taken at Mount Wilson observatory
- Shape model deduced from light curve
- Asteroid Juno Grabs the Spotlight
- "Elements and Ephemeris for (3) Juno". Minor Planet Center. Archived from the original on 2015-09-04. (displays Elong from Sun and V mag for 2011)
- 3 Juno at the JPL Small-Body Database


The commercial and industrial use of laser diodes has dramatically increased recently. The optical characteristics, small size, and ruggedness of laser diodes have allowed many new uses to be commercialized.
The output of laser diodes is very bright considering their small size. Today, hundreds of watts of power are commercially available from laser diodes operating under continuous wave (CW) conditions in packages as small as a few cubic inches. This characteristic makes these devices suitable for cable TV transmission, high definition TV (HDTV) development, and medical applications.
In addition, compared to other types of lasers , laser diodes use very little power. Most laser diodes operate with voltage drops of less than 2 V with power requirements determined by their current setting. Overall efficiencies greater than 30% are typical in the case of laser diodes.
Since laser diodes are made of semiconductor materials, they do not require the fragile glass enclosures or mirror alignment typical of gas lasers. The resulting ruggedness and small size allow laser diodes to be used in environments and spaces in which other types of lasers cannot operate.
Coherence and single wavelength characteristics of laser diodes enable the outputs of these devices to be focused to a diffraction limited spot size. The size of the resultant spot is dependent on the wavelength of the laser - the shorter the wavelength of light, the smaller the size of the spot that can be generated. Operation at shorter blue and UV wavelengths makes smaller spot sizes possible, consequently allowing more information to be stored on optical disks at a higher density.
Another advantage of laser diodes is that they can be directly modulated at high frequencies. By modulating the drive current, the output of the laser diode is modulated with frequencies up to several GHz in high-speed data communications.
Various Types of Laser Diodes
Low-Power Laser Diodes
Low-power laser diodes come in a variety of packages. Most have a monitor photodiode integrated with the laser diode. Generally, laser diodes emit light from both ends of their cavity. By monitoring the rear facet output beam of the laser diode, one can maintain the laser at a constant power level. For power levels in the range of 1 W or less, the most common package used is the TO-Can style and is available in either a 5.6 mm or 9 mm diameter base (Figure 1). Other packages include TO-3 packages for higher power laser diodes (>1 W).Figure 1Laser diode and monitor photodiode arrangement in can-style package.
Telecommunication laser diodes come in either butterfly or DIL (Dual-In-Line) 14-pin packages (Figure 2). Most include both a thermo-electric cooler (TEC) module, and all include a mounting plate for heat dissipation.(a)(b)
Figure 2Two varieties of telecommunication laser diodes: (a) dual-in-line 14 pin, and (b) butterfly package.
Many other packages are used including coaxial cans for pulsed laser diodes and a variety of fiber pigtailed laser diodes with CD/DVD style laser diodes integrated into a custom designed housing that includes focusing optics and a fiber output.Figure 3Scanning electron micrograph of a 2-dimensional VCSEL array. Photo by Axel Scherer, courtesy of Picolight, Inc., Boulder, Colorado.
Other structures include Vertical Cavity Surface Emitting Lasers (VCSEL) and Master Oscillator Power Amplifier (MOPA) lasers. VCSEL laser diodes (Figure 3) can be fabricated in 2-D arrays for use in optical computing, printing and communications. Their laser structure has a circular aperture allowing the output beam to be easily collimated using a simple spherical lens. MOPA lasers have been developed to increase the output power of single-mode laser diodes while maintaining a narrow line width. These laser diode structures have an oscillator section that produces a very narrow spectral output, and an integrated power amplifier section that increases the output power without affecting the spectral output.
Applications requiring narrower spectral linewidths need structures that confine the lasers oscillations to a single-mode. Index guided devices provide the necessary confinement that result in single-mode output beams with little or no astigmatism. However, divergence of the light emitting from a laser diode is very pronounced with full width half maximum (FWHM) angles of up to 40 degrees in the perpendicular axis (θ⊥) and 10 degrees in the parallel axis (θ||). This divergence results in a rapidly expanding elliptical cone. Gain-guided laser diodes tend to have greater differences between the two angles than index-guided laser diodes. Figure 4 illustrates beam divergence in the theta parallel and theta perpendicular axes.Figure 4Schematic representation of an index guided device and its diverging output beam profile.
Single frequency laser diodes are another interesting member of the laser diode family. These devices are now available to meet the requirements for spectroscopy and high bandwidth communications. Other advantages of these structures are lower threshold currents and lower power requirements. One variety of this type of structure is the distributed feedback (DFB) laser diode (Figure 5). It has been developed to emit light at fiber optic communication wavelengths between 1300 nm and 1550 nm.Figure 5Various single frequency semiconductor lasers: DFB, DBR, and external grating devices.
Since lasers emit light over a narrow wavelength range, they can also be used for sensing and spectroscopy. Examples include the detection of trace gases, and elements that react to light at very defined wavelengths. By proper selection and wavelength tuning of a laser diode one can detect these elements.
High-Power Laser Diodes
More recently high-power laser diodes operating in the wavelength range of about 0.81.1 micron have been getting much attention due to their widespread applications. These lasers are used in optical pumping of solid-state lasers, such as the Nd:YAG, replacing traditional flash lamp designs. High-power laser diodes are tuned to the absorption band of the dielectric crystal resulting in much more efficient pumping of the laser rod, from which a high-power focused coherent beam of light is emitted. This beam can then be used in a variety of industrial, medical, and military applications. Laser diodes have been developed to match the absorption bands of a variety of dielectric crystals in a broad wavelength range. Figure 6 shows two common variations of high-power laser diode packages.(a) Bar-Type(b) S-Type
Figure 6 Two common high-power laser diode packages.
In addition to applications involving the pumping of solid-state laser rods, high-power laser diodes are also very useful for fiber optic telecommunication purposes. In these applications, a high-power laser diode operating at the wavelength of 980 nm is used as a pump source for erbium doped fiber amplifiers. Such optical amplifiers are used in direct optical amplification of the 1550 nm wavelength telecommunication signals propagating along the long haul telecommunication lines. In this fashion, the need to use electrical amplifying circuits is eliminated and the optical signals are directly amplified, with greater efficiency, and without the need to convert the light signal to an electrical signal and back.Figure 7Schematic diagram showing a typical high-power stacked bar laser diode package.
By stacking several high-power laser diode bars on top of one another, it is possible to make stacked laser diode arrays (Figure 7) with output powers potentially in the range of kilowatts. Such devices open up a wide range of new possibilities in such applications as industrial welding and precision cutting of metals and various other materials.
Threshold Current and Threshold Current Density
Perhaps the most important parameter of laser diodes to be measured is the degree to which they emit light when current is injected into the device. This generates the Output Light vs. Input Current Curve, more commonly referred to as the L.I. Curve shown in Figure 8. As the injected current is increased, the laser first demonstrates spontaneous emission that increases very gradually until it begins to emit stimulated radiation, which is the onset of laser action. The first parameter of interest is the exact current value at which this phenomenon takes place. This is typically referred to as the threshold current and is denoted by the symbol Ith. It is generally desirable that the threshold current be as low as possible, resulting in a more efficient device. Thus, a threshold current is one measure used to quantify the performance of a laser diode.Figure 8A typical Light vs. Current (L.I.) curve associated with a high-power laser diode. Ith represents the threshold current at which the device begins to lase. The efficiency of the laser in converting electrical power to light power is determined by the slope of the L.I. curve, denoted by the change in output power over the change in current (ΔP/ΔI). The inset schematically shows a broad area (100 µm wide stripe) laser diode emitting radiation from both its front and back mirror facets.
Threshold current is dependent on the quality of the semiconductor material from which the device is fabricated, and also the general design of the structure of the device waveguide. However, threshold current is also dependent on the size and area of the laser device. One laser diode could demonstrate a much higher threshold current than another device and yet be considered a much better laser. This is because the area of the device can be large. A laser that is wider or longer obviously requires more electrical power to reach the onset of laser action than a laser of a smaller area. As a result, when comparing the threshold current values of different devices, it is more appropriate to talk about threshold current density rather than threshold current. Threshold current density is denoted by the symbol Jth and is determined by dividing the experimentally obtained threshold current value Ith by the area of the laser. It is always desirable for a laser to have a low threshold current density value. Threshold current density is one of the parameters that is a direct indication of the quality of the semiconductor material from which the device is fabricated. In comparing the performance of various laser devices one must compare the threshold current density values rather than the threshold current values. In calculating the current density of the laser, it is necessary to accurately measure the area of the laser through which current is being injected. This is only possible in broad area type lasers with stripe widths on the order of 100 microns or more. In such cases, the area through which the current is flowing is very much the same as the area of the metallic contact of the laser. In cases of ridge lasers the width of the ridge is only a few microns while, due to current spreading, the actual width of the channel through which current is flowing could be considerably more. This makes it impractical to accurately determine current density values in cases of narrow stripe ridge lasers.
Slope of the L.I. Curve
Just as it is desirable to reach laser action at as low a threshold current as possible, it is also desirable to get more and more light out of the device with the expenditure of as little current as possible. In other words, you would want to be able to increase the input current slowly and yet achieve rapid increase in the output light emission. A laser diode, which has a good rate of converting the input electric power to output light power, is obviously a device that is performing well. A direct measure of the ability of the device to do this is the slope of the L.I. curve. This slope is denoted as ΔP/ΔI and has the units of Watts per Amperes (W/A), or in the case of low-power lasers (mW/mA). ΔP/ΔI, which is the slope of the L.I. curve above the threshold current Ith, directly tells us how many Watts of power the laser outputs for every 1 Amp increase in its input current. Other important parameters are typically extracted from measurement of the ΔP/ΔI parameter. These include the External Differential Quantum Efficiency, Internal Quantum Efficiency, and Internal Loss parameters. Please refer to Newports Application Notes for an in-depth discussion of these topics and the description of the experimental setups and calculation procedures needed to accurately determine the above-mentioned parameters.
In most applications, the ability of the laser diode to perform well at elevated temperatures is of great interest. This is especially of concern in the case of high-power laser diodes where the amount of power generated causes the device temperature to rise significantly. As a result, it is of utmost importance for the semiconductor crystal to be robust enough so as not to suffer from device deterioration at high temperatures. The characteristic temperature of the laser diode, which is commonly referred to as To (pronounced T-zero), is a measure of the temperature sensitivity of the device. Higher values of To imply that the threshold current density and the external differential quantum efficiency of the device increase less rapidly with increasing temperatures. This translates into the laser being more thermally stable. In order to measure the characteristic temperature of a laser diode it is necessary to experimentally measure the L.I. curve of a laser at various temperatures. The results are then tabulated and the To determined. Typically, people perform these measurements at temperatures ranging from 15 degrees Celsius up to about 80 degrees Celsius, and at 5 or 10-degree increments. Conventional AlGaAs lasers usually have To values above 120 degrees. Please refer to Newports Application Note 1, Test and Characterization of Laser Diodes for more on this topic including the experimental techniques and calculation methods.
Dynamic Series Resistance
The series resistance of the laser diode is typically determined through calculating the derivative of the voltage versus injection current characteristic curve of the device. One way of doing this is to use a computer program to analytically determine the first derivative of the voltage versus current characteristic curve of the device that is obtained experimentally (more on this topic in Newports Application Note 1). High series resistance values for a laser diode could be the result of low quality metal ohmic contacts deposited on the two sides of the device. As a result, measurement of the series resistance value can be a means of assessing the quality of the metallic contacts deposited on the laser.
As laser diodes have evolved over the past fifteen years, various structures have been developed with different characteristics. The first laser diodes used gain-guided structures, which are easy to fabricate, resulting in a reliable device at low manufacturing costs. This type of structure supports multiple modes, resulting in multiple spectral lines and astigmatism. Astigmatism is a condition in which the apparent focal points of the two axes do not coincide. It limits the ability to focus the laser beam to a small spot size (Figure 9) and complicates focusing the output beam to a sharp well-defined point.Figure 9Schematic diagram showing the problem of astigmatism.
The ratio of the parallel and perpendicular vectors of polarization is called the polarization ratio. Laser diodes can reach polarization ratios of 100 to 1 or more when operated near their maximum output power ratings.
Collimation of Laser Diode Beams
Since the output of a laser diode is highly divergent, special collimating optics are required. Either molded aspheres or multiple element glass lenses have been traditionally used to collimate the output. These collimators typically have a numerical aperture of 0.5 or better to collect the entire laser output beam.
Using lenses, the output light of a laser diode can be formed into a collimated beam with little divergence. Such a highly directional collimated beam of intense light has many uses, such as in the alignment of large structures in civil engineering or in the read head of CD players. Also, due to the coherent nature of laser light, its properties stay the same in space and time. This is useful in interferometric measurements of material deformities.
If a gain-guided laser diode beam is collimated or being focused, then a cylindrical lens is used to account for astigmatism. A long focal length lens is used to compensate for the astigmatism and then the collimating lens can provide a beam that has little divergence in both axes.
The collimated beam is still elliptical and can be circularized using an anamorphic prism pair. Either the major axis is compressed or the minor axis is expanded to make a circular beam. Focusing the output beam of a laser diode into a single-mode fiber will also result in a circularized output. The fiber acts as a filter since only one mode propagates down the fiber. The output from the fiber is a circular, conical beam with a highly Gaussian shape, and low numerical aperture (N.A. <0.1). A simple spherical lens is used to complete the collimation.
Newer techniques for collimating laser diodes include micro lenses and diffraction optics, both resulting in very compact packages. Micro lenses are bonded just in front of the emitting apertures of the laser diode. The complete assembly fits inside the laser diode package. Diffraction optics are manufactured using photolithography techniques that result in high repeatability and extremely low cost in large quantities. The diffraction optics are mounted externally but still result in extremely small laser diode packages.
Spectral Characteristics of Laser Diodes
The optical spectrum of laser diodes depends on the particular characteristics of the lasers optical cavity. Most conventional gain or index-guided devices have a spectrum with multiple peaks, while distributed feedback (DFB) and distributed Bragg reflector (DBR) types of devices display a single well-defined spectral peak. Figure 10 shows a comparison between these two spectral behaviors.Figure 10Multimode versus single-mode spectra
The number of spectral lines that a laser is capable of supporting is a function of the cavity structure, as well as the operating current. The result is that multimode laser diodes exhibit spectral outputs with multiple peaks around their center wavelength. The optical wave propagating through the laser cavity forms a standing wave between the two mirror facets of the laser. The distance L between the two mirrors determines the period of oscillation of this curve. This standing optical wave resonates only when the cavity length L is an integer number m of half wavelengths existing between the two mirrors. In other words, a node must exist at each end of the cavity. The only way this can take place is for L to be exactly a whole number multiple of half wavelengths λ/2. This means that L = m(λ/2), where λ is the wavelength of light in the semiconductor matter and is related to the wavelength of light in free space through the index of refraction n by the relationship λ = λo/n. As a result of this situation, there can exist many longitudinal modes in the cavity of the laser diode, each resonating at its distinct wavelength of λm = 2L/m. From this you can note that two adjacent longitudinal laser modes are separated by a wavelength of Δλ = (λo)2/2nL. Figure 11Effects of operating current level on the output spectrum.
Even single-mode devices can support multiple modes at low output power as shown in Figure 11. As the operating current is increased, one mode begins to dominate until, beyond a certain operating power level, a single narrow line width spectrum appears.
Center Wavelength Changes with Temperature
The center wavelength of a laser diode is directly proportional to its operating temperature. There is a linear relationship between temperature and center wavelength (as shown in Figure 12). As temperature increases, so does the center wavelength of the laser diode. This characteristic is useful in spectroscopy applications, laser diode pumping of solid state lasers and erbium-doped fiber amplifiers, where the wavelength of emission of the laser diode can be accurately temperature-tuned to the specific properties of the material with which it is interacting.Figure 12Effects of temperature on center wavelength.
Single-mode lasers exhibit a phenomenon called mode hopping (Figure 13), in which the center frequency of the laser diode hops over discrete wavelength bands and does not show continuous tuning over a broad range. One can change the wavelength where the discontinuities take place by making small adjustments to the drive current. When selecting a specific laser diode for an application requiring a specific wavelength, such as spectroscopy, mode hopping must be taken into account when temperature tuning the device.Figure 13Mode hopping observed while temperature tuning a single-mode laser diode.
Laser Diode Lifetime Requirements
The operating lifetime of a laser diode is dependent on its operating temperature. A high quality laser diode operating at 20°C could have a lifetime in excess of 100,000 hours. Failure of a laser diode is usually defined as the point in time when the operating current required to maintain a specified output power is increased by some percentage (50%) of the initial current. The temperature measured is the case temperature of the laser diode package. The manufacturer usually provides lifetime curves for specified output powers.
Effects of Electrostatic Discharge on Laser Diodes
Laser diodes are extremely sensitive to Electrostatic Discharge (ESD) and must be handled with care. When handling a laser diode, always follow the manufacturers instructions for removing the laser diode from its shipping container. You must take care to ensure that your laser diode is properly protected during handling. Generally, operators must be properly earth grounded and should use conductive finger guards when handling a laser diode. All equipment must be properly earth grounded. You should always closely follow the manufacturers specifications and instructions for proper heat sinking. It is strongly recommended not to solder directly to a laser diode package or its electrical leads. It is best to make all electrical connections to a socket, such as a transistor socket, into which the laser diode can be inserted.
Current Source Requirements for Laser Diodes
Laser diodes require a low noise current source called a laser diode driver. Standard power supplies usually operate as constant voltage sources and do not have the necessary protection circuits that laser diodes need. They are also too noisy for most laser diode applications. Also, laser diodes are easily damaged from voltage and current fluctuations and transients. Specialized circuit designs have been developed to protect laser diodes from being damaged. The first stage of protection includes input AC power filtering and high-speed transient detection circuits. Low voltage and AC line transient detection circuits, and shielded transformers, provide additional protection.
Momentary internal transients within the power supply may occur when the output current is turned on or off. Laser diode drivers should have the output to the laser diode shorted whenever the output is turned off. This is accomplished by using redundant FET and relay shorting devices across the output. During the turn-on phase, these shorting devices protect the laser diode from both voltage and current transients. After a delay of several seconds, the output current slowly ramps up over several milliseconds to several hundred milliseconds to the set point value.
Another necessary feature of laser diode drivers is the independent current limit. This limit is set separately from the set point value and overrides any condition that may cause the output current to exceed the laser diodes maximum current rating. Some current sources utilize a software programmable power limit that works similarly to the current limit. While the current limit is hardwired, the power limit must be programmed and one must therefore know the responsivity of the photodiode to properly set the power limit. Both work independently to safeguard your laser diodes.
Temperature Control for Laser Diodes
Since many parameters depend on the temperature of the laser diode, it is important to set and maintain a stable temperature using a thermo-electric temperature controller. Most laser diode applications use Thermoelectric (TE) coolers based on the Peltier Effect to maintain a constant temperature. TE modules are semiconductor heat pumps that move heat from one side of the device to the other. Depending on the direction the current flows through the TE cooler, you can either heat or cool a laser diode. Several types of temperature sensors are used: thermistors, I.C. sensors, and platinum resistive temperature devices (RTDs). The most commonly used is the thermistor because of its small size and fast response time. Thermistors and RTDs are nonlinear resistance devices. Both require a small accurate current source to bias them. Changes in temperature result in resistance changes, with the voltage drop across the device proportional to temperature. Each device has a characteristic equation that converts resistance to temperature. The Steinhart-Hart equation is used to convert a thermistors resistance to temperature and uses two or three constants depending on the accuracy required.
I.C. sensors are linear devices whose outputs can easily be converted and displayed in °C. Although they are linear, they are not as accurate as thermistors. Figure 14 summarizes each temperature sensor and its advantages. RTDs are primarily used where one needs an extremely stable sensor for very long-term and accurate temperature controlled applications. The major drawback of RTDs is their small resistance change, which makes it difficult to measure small absolute temperature changes.
Thermistors, on the other hand, have extremely large resistance changes, making it easy to measure small changes in temperature. They are also the smallest of the three types of sensors, which make them ideal candidates for integration into laser diode packages. Laser diode packages with integral TE coolers use a 10kΩ thermistor as the temperature-sensing device.
Test and Characterization of Laser Diodes
It is often necessary to quantitatively assess the quality, performance, and characteristics of laser diodes. This is done through performing a series of experiments and obtaining various parameters from which we can determine how well the laser diode is performing. It is then possible to establish whether the laser diode meets the desired specifications.Figure 14Comparison of commonly used temperature sensors.
Figure 15 shows an example of an experimental laboratory setup that can be used to perform full characterization of high-power laser diodes accurately and rapidly. This setup can be fully automated by using a PC and control software such as LabView for full automation of the instrumentation control and data acquisition.
The centerpiece of this experimental setup is the laser diode mount and the Integrating Sphere Detector System. The Laser Diode Mount is designed to provide simple air-cooling for high-power laser diodes.Figure 15A typical computer controlled laser diode test and characterization setup.
In laser diode measurements, the use of an integrating sphere setup is absolutely necessary when performing precise measurements of the output light power. Laser diodes have a highly divergent beam profile and the use of an integrating sphere ensures that all of the light emitted by the laser diode is collected and measured. In addition, it makes the measurement insensitive to exact detector positioning. The signal generated by the detector is then measured with a calibrated optical power meter. This setup makes it possible to accurately measure the output light of laser diodes of various wavelengths. The Optical Measurement System is generally computer controlled using GPIB or USB.Figure 16Typical experimental setup using a probe station arrangement for pulse characterization of laser diode chips and laser diode bars not mounted onto heatsinks.
In addition, the Integrating Sphere could be equipped with a fiber optic port. This is used for sampling the light and channeling it to the input of an optical spectrum analyzer. In this fashion, it is possible to perform simultaneous measurements of the laser diode optical spectrum and peak wavelength of emission, in addition to the L.I.V characteristics.
The process of packaging laser diodes is very labor intensive and an expensive part of the manufacturing of these devices. Because of this, it is generally necessary to fully assess the quality of the semiconductor wafers from which the laser diodes are fabricated prior to full device manufacturing. In addition to a series of structural, electrical, and optical characterization tests that the wafers undergo, most often broad area lasers are also processed from the wafers and then tested in order to determine whether the wafer is a Device Quality Wafer or not. This prevents low quality material to be used for manufacturing of devices. Since these devices are tested without being bonded on heat sinks, and are not fully packaged, it is absolutely necessary that all testing and characterization is done under low duty cycle pulse current conditions. In this fashion, heat dissipation is not an issue and it is possible to determine the characteristics of the devices without the need to fully package them. Figure 16 shows the experimental setup for the characterization of laser diodes under pulse condition. Note that in this case, a probe station is used to probe and inject current into each device and the laser diode driver is a current pulse generator.
Using such experimental setups it is possible to perform full laser diode testing and characterization; leading to the determination of such significant parameters as the threshold current and threshold current density, external differential quantum efficiency, internal quantum efficiency, internal loss, spectrum and peak wavelength of emission, series resistance, and characteristic temperature.


Description: The Ludendorff Bridge was a railroad bridge across the Rhine in Germany, connecting the cities of Remagen and Erpel.
The bridge is famous for its capture by Allied forces in the Second World War. The bridge was an important strategic point in WWII because it was the only remaining bridge which led over the Rhine River into Germany and Berlin.
he bridge had been built in 1916 during the First World War to facilitate transport to the Western Front. Designed by Karl Wiener, it was 325 meters long, with two rail lines and a walkway. It was named for the German WWI general Erich Ludendorff, one of the bridge's proponents.
On March 7, 1945, troops of the US 9th Armored Division reached this last intact bridge over the Rhine, after German defenders failed to demolish it, despite several attempts. Lt. Karl Timmermann was the first officer over the bridge. By the Allies, this was hailed as the "Miracle of Remagen". General Eisenhower called the bridge "worth its weight in gold." It remained intact, but severely weakened, despite several further German efforts to destroy it. 8,000 men crossed it in the first 24 hours alone.
Hitler's reaction was to court-martial five officers, four of whom were quickly executed.
Ten days after its capture, the bridge collapsed, killing over 20 engineers working to strenghten the bridge. However, by then the Americans had established their position and had additional pontoon bridges in place.
A Hollywood film, The Bridge at Remagen was made in 1969. The surviving towers of the old bridge now house a museum.


What causes chronic joint pain?
What causes chronic joint pain OTHER than arthritis? I'm only 22, so I'm way to young to have arthritis. But my knees have started hurting almost all the time. I'm a runner, but I take it pretty easy, so I don't think it's a sports injury. What could this be?
Chronic joint pain is a common condition, although more common in the elderly. I would suggest seeing your primary doctor (or getting one if you don't have one) as there are some serious conditions that should be ruled out. Arthritis is a generalized term that refers to inflammation of the joints. When people generally say arthritis (as I think you are referring to) they are talking about osteoarthritis. Osteoarthritis, as you suggest, is more common in the elderly. This is essentially caused by wear and tear on the joint that results in the cartilage being worn down. This results on "bone on bone" that results in pain. The wear and tear happens over time, so it is more common in the elderly--but many things can accelerate this. Risk factors include extra weight (for example obese people often get knee osteoarthritis) and repetitive stress. If you are an avid runner--it is possible you have early onset osteoarthritis. Other possibilities are also important to consider. A common cause of joint pain is stress on the ligaments and muscles surrounding the joint, for example "runner's knee" or "dancer's hip". This is often the case in active young people--especially if there is bad shoe support or running form. See your doctor about this as physical therapy can help strengthen the muscles and overall improve the symptom. Pain medicines can also help reduce the inflammation. The other thing to consider is other forms of arthritis--namely rheumatoid arthritis. This can occur in multiple joints and occurs because of an autoimmune attack by the body's immune system on its own joints. Rheumatoid arthritis is the most common, but other conditions like lupus can also cause this. It is more common in women. This can cause many other heart, lung and kidney complications so should be diagnosed early. Chronic joint pain is a common condition. Serious conditions need to be ruled out. See your primary doctor.
This answer is for general informational purposes only and is not a substitute for professional medical advice.
If you think you may have a medical emergency, call your doctor or (in the United States) 911 immediately. Always seek the advice of your doctor before starting or changing treatment. Medical professionals who provide responses to health-related questions are intended third party beneficiaries with certain rights under Zocdoc’s Terms of Service.


Written by Gary Presant, MD
Monday, 05 October 2009
Asthma is a common lung disease that causes repeated bouts of wheezing, shortness of breath, chest tightness, and coughing, especially at night or in the early morning. A person with asthma has difficulty breathing because of inflammation and narrowing of the airways.
What is going on in the body?
In a person with asthma, the airways narrow as a result of irritation and inflammation. During an asthma flare-up or "asthma attack," muscles of the airway tubes, or bronchi, tighten. The reaction in the lungs is out of proportion with the amount of stimulation experienced. The inflammation and tightening in the airways increases, trapping air in the lungs. The overreaction to the trigger causes excess mucus to form in the lungs. The person cannot take in a full breath and feels short of breath.
Sometimes the reaction to the trigger causes swelling throughout the entire bronchial tube. The opening in the center of the tube then becomes smaller, and breathing becomes more difficult. When the muscles relax, the bronchial tubes open wider. Asthma symptoms then resolve, and breathing becomes easier.
What are the causes and risks of the disease?
Asthma is caused by an immune system response. The immune system overreacts to triggers and causes the airways to become inflamed and tight. Often there are provoking factors, or triggers, that cause asthma symptoms. Triggers differ from person to person. Asthma triggers include:
- allergies to food such as peanuts or to foods with sulfites, such as beer, wine, processed foods, and shrimp
- cold and dry air and wind
- dust and dust mites
- hormonal changes resulting from pregnancy or menstruation
- indoor and outdoor pollution from exposure to fumes, paint, fireplace smoke, or perfume
- medicine allergies
- pets with fur or feathers
- smoke inhalation
- viral infections, such as a cold or flu
What are the treatments for the disease?
Successful treatment of asthma involves two important factors:
- avoiding known irritants or triggers
- taking medicines to reduce airway inflammation
Avoiding known irritants is key to controlling asthma. Avoid anything that one can see or smell in the air, especially cigarette smoke, dust, and strong chemical odors. Many people with asthma also have allergies. Allergic reactions can trigger an asthma flare-up. Avoiding things that cause the allergies, called allergens, is important. Controlling allergies with appropriate medicine or allergy shots can often improve asthma symptoms.
Medicines for treatment of asthma include both quick-relief and long-term-control medicines. The healthcare provider will prescribe the appropriate medicines for each individual. In general, the following principles are used:
- people who have asthma only intermittently are given quick-relief medicines
- people with persistent asthma are often given both quick-relief and long-term-control medicines
- people with exercise-induced asthma symptoms may be told to take quick-relief or long-term-control medicines right before exercise
Quick-relief medicines work within minutes. They prevent or help reduce the tightening of the muscles of the bronchial tubes. They are used when a person experiences an asthma attack or sudden shortness of breath. Short-acting beta-2 agonists, such as albuterol, are used for quick symptom relief. These medicines are usually taken through a metered dose inhaler or nebulizer.
Long-term-control medicines are taken on a regular basis to calm the airways and prevent symptoms. They are not effective for quick relief during an asthma attack. These medicines include:
- cromolyn and nedocromil, which act on the immune system to reduce inflammation
- inhaled or oral corticosteroids, which prevent swelling and irritation of the airways
- leukotriene modifiers, which block the chemicals that start airway inflammation
- long-acting inhaled beta-2 agonists, which help relax the airways
- methylxanthines, which relax the airway muscles
What are the side effects of the treatments?
Short-acting beta-2 agonists and anticholinergics may cause the following side effects:
- dry mouth and difficulty speaking
- high blood pressure
- racing heartbeat
Corticosteroids have fewer side effects when given by inhaler than when they are taken orally. Side effects may include:
- bone thinning
- change in voice tone
- growth problems in children
- muscle weakness
- oral thrush, a yeast infection in the mouth
- weight gain
Long-acting beta-2 agonists may cause the following side effects:
- difficulty sleeping
- dry mouth
- feeling nervous or shaky
Leukotriene modifiers may cause:
- abdominal pain and diarrhea
- nausea and vomiting
- sore throat
Methylxanthines may cause:
- difficulty sleeping
- irritability and shakiness
- nausea and vomiting
Cromolyn and nedocromil may cause:
- a bad taste in the mouth
- chest tightness
What happens after treatment for the disease?
Effective treatment of asthma reduces inflammation and tightening of the airways, lowering the frequency of asthma attacks. Successful treatment allows people with asthma to enjoy life without significant breathing problems.
How is the disease monitored?
A person with asthma can monitor breathing at home with a device called a peak flow meter. Some people use peak flow meters every day and keep a record in their asthma diary. Airway changes show up on a peak flow meter before symptoms are even felt. Following the treatment plan at this time will often prevent an asthma attack from getting any worse.


Avoid Sport Injuries
How do you avoid sport injury? This is a common question for those involved in fitness – after all, if you frequently suffer form injuries it will stop you from working out.
When you want to avoid sport injury, there are a few tips to follow:
- Always warm up: Warming up is the first step to avoiding injuries. When you warm up, you allow your muscles, tendons and ligaments to get ready for the activity ahead. The best way to warm up is to start with ten minutes of easy cardio – enough to elevate your heart rate and get a light sweat going. Many people also stretch as part of their warm up, but stretching is best saved for your cool down.
- Increase distance and speed gradually: When you start working out, the temptation is to leap into it – if three miles is good, six miles must be better! However, if you want to ensure that you are able to keep working out, take the time and gradually build up your speed and distance. The rule of thumb for runners is to increase your mileage by no more than 10% per week – that holds good for pretty much any type of workout. Increasing your time or distance by 10% per week will allow your body to gradually get used to the strains you are putting it under.
- Always wear appropriate clothing and shoes: Running and workout shoes are designed to offer support where required – don’t skimp on cheap or old shoes, they won’t be fit for purpose, and can lead to injuries. Similarly, the right clothing will not only help you look better it will also make your workouts safer and more comfortable – no old baggy sweaters tangling up in weights machines or bike wheels!
- Vary your workouts: Doing the same thing over and over can lead to injury – instead, try different workouts (running, swimming, spin class, salsa, etc), and if you are a runner, vary the terrain, running on grass or natural surfaces wherever possible to reduce the impact.
- Cool down properly: Workout shouldn’t finish too suddenly – you need to allow time to slow down gradually, allowing your heart rate to fall. This is also the best time to do your flexibility work – stretching – while your muscles are warm.
- Do not train while ill or excessively tired: Finally, you need to learn to listen to your body. While you don’t want to stop exercising every time you don’t feel 100%, if you are ill or excessively fatigued, then take a day off – you’ll come back stronger when you are well again.
By following these simple tips, you can ensure that you are able to keep working out safely and comfortably, enabling you to reach your health and fitness goals.


Life in the Longhouse
The Iroquois lived in longhouses with their clan ( orextended families), numbering between thirty and sixty people or fifteen to twenty families (Doherty 16) (Kalman 10). A longhouse was sectioned off into apartments with individual fireplaces in the middle hall ( Kalman 8). Two families shared a fireplace, each possessing one of the two compartments across the hall (Doherty 16). In the compartments platforms were built so that the Iroquois did not have to sit on damp floors; the platforms were 37 meters high and overlaid with reed mats and furs (Doherty 34).
Clans and the Matriarchy
The Iroquois was a matrilineal society, which means that heritage passed through the mother's side (Doherty 16). Each longhouse had a clan matron (Kalman 10). All men married into the clan. Clans traced their lineage back to and shared a particular ancester, and each longhouse kept a record of the descendants of their clan (Doherty 17). Clans were represented by animal guardians (Kalman 10). The wolf, bear, beaver, turtle, deer, snipe, heron, and hawk are believed to be the eight clans of a tribe (Doherty 16). These animal guardians were carved as emblems over the doorway of each longhouse and on hte cradleboards of babies (Kalman 10) (Doherty 29).


In this lesson, we'll discuss some basic guidelines and tips for reading and understanding scholarly research articles by looking at the make-up of these articles.
The specific areas of focus include:
Reading and understanding scholarly research articles can be a little bit different from reading traditional forms of articles, such as those that appear in magazines like Time or Newsweek. This is because research articles are written in a different style intended for a more academic audience.
In order to understand these articles better, let's take a look at the different components or sections typical of research articles.
When reading a research article, you first want to know what exactly is being studied. The best place to look for that information is in the abstract.
The abstract is a structural component specific to scholarly research articles, and is essentially a short summary -- about one paragraph long -- at the very beginning of an article.
Most importantly, the abstract identifies the variables that are talked about in the experiment or the research.
If the abstract states that the article is a study about soda and children, then you know that those two subjects are the variables in this study.
The abstract also provides a quick overview to help you understand exactly what the methods and conclusions are for the experiment itself.
If you need a quick understanding of the material covered, or if you need to refer back to the methods or conclusions later, the abstract is a good place to look.
Next, you want to understand the most important information about this topic or area of study.
Say you're looking at an article on a particular area in developmental psychology. If you don't necessarily have a clear understanding of this area, then the introduction is a good place to start.
The introduction provides any kind of prior research about the topic that's being addressed within the paper. In other words, it gives you a good amount of background knowledge of what the author is talking about.
The introduction can also be a good place to look for other research that you might want to understand within this area; you can then go to the end of the paper for the references section in which citations for other papers are provided.
You can use the introduction as a jumping-off point to find more research in the particular area of study discussed in the article.
Next, you might want to know exactly how the research or study was conducted, or how it functions within the paper you're reading. This information would be found in the methods section, which tells all about the study itself so that it can be reviewed and replicated.
The methods section provides specifics such as:
The methods section is also a good place to look if you want to understand potential sources of bias or confounding variables.
In other words, the methods section can be helpful if you want to know what might have influenced the study and in ways that were unintended. One way this can occur is if the researcher used an invalid test, meaning a test that doesn't necessarily measure what it claims to.
If the researcher said he or she was studying IQ, but used a Rorschach inkblot test, you could see that those two don't fit together. This would then lead to incorrect conclusions or data.
Additionally, some studies have errors in regards to the people that were used, or methods that were confusing or not necessarily related to the topic. The study may simply have had too many elements.
Specific components of the study as well as any errors that occurred are the aspects that you want to look at when reviewing the methods section of a paper.
Finally, when you want to know what the research proves, you jump down to the analysis, or conclusions, section at the end of the paper.
This section tells you how research relates to the subject that's being discussed in the introduction, and makes connections to the methods and data.
When looking at the conclusions section of a paper, it's important to think about whether the conclusions made are logical, and whether the results show what the researcher claims they show.
If the conclusions section states that soda causes children to have lower IQs, you would need to consider whether the data is saying that as well. If the research doesn't prove this statement, then it would be an incorrect assumption that isn't logical for the researcher to make.
In the conclusions section especially, a researcher needs to be careful that the statements aren't being applied too broadly to everybody based on the research. If only certain people were being tested within the experiment, they can't necessarily say that the conclusions will be the same for all people.
When looking at the conclusions section of a research article, you want to make sure that the conclusions are being made correctly for the particular populations or people that were being studied.
In this lesson, you learned that reading and understanding scholarly research articles entails a different process than reading traditional articles. This is because research articles are intended for a more academic audience.
You now understand that there are four basic sections or components of research articles: abstract, introduction, methods, and analysis/conclusion.
Keep up the learning and have a great day!
Source: Adapted from Sophia tutorial by Erick Taggart.
Anything that can be changed; anything that can affect the results of an experiment.


About the Commission
Eye health affects nearly everyone at some point in our lives. Worldwide, there are currently 1.1 billion people living with vision impairment, and hundreds of millions more have ongoing eye care needs.
Yet there are existing, highly cost-effective treatments for more than 90% of people living with impaired vision, meaning they are suffering needlessly. This has a wide social and economic impact globally, particularly in low and middle-income countries.
This report builds on the worldwide initiative for the elimination of avoidable blindness, “VISION 2020: The Right to Sight”, the publication of WHO’s World Report on Vision (2019) and the 73rd World Health Assembly resolution on integrated people-centred eye care (2020).


Department of Instructional Technology and Learning Sciences, Utah State University, Logan, Utah
* Address all correspondence to: Aubrey Rogowski, Department of Instructional Technology and Learning Sciences, Utah State University, 2830 Old Main Hill, Logan, UT 84322-2830; Tel.: (+1) 435-797-2694, E-mail: firstname.lastname@example.org
Libraries are increasingly offering activities and programs that engage youth in science, technology, engineering, and math–rich “Making.” However, many librarians do not have access to necessary training, resources, or relevant content knowledge to help implement these kinds of Maker programs. This article describes a design-based research project in which we first engaged in sustained contextual inquiry to better understand the work practices of school and public librarians in small town and rural libraries and their perceptions of implementing Maker activities. Findings informed the design of online instructional guides to help librarians learn to implement informal beginner-level Maker programming and activities for youth. We describe three genres of online instructional guides and the design guidelines that inform them. We also describe our process for testing online guide utility and usability.
KEY WORDS: online instructional guides, open access, Making, STEM, libraries, librarians
Libraries are increasingly expanding and modifying their spaces and services to better accommodate collaboration and learning. One growing area in this transformation is the provision of programs and activities that engage youth in science, technology, engineering, and math (STEM)–“Maker” activities and programming (Martin, 2015; Subramaniam et al., 2014). Maker activities can support youth in pursuing their interests by creating artifacts that blend digital and physical technologies, tinkering with robotics, or coding in environments such as Scratch (Lee et al., 2018b; Sheridan et al., 2014).
In response, many librarians are taking on greater leadership and technology roles to support these new Maker-related activities (Preddy, 2013; Sands et al., 2018). These roles may extend beyond what was provided by their previous education or experience. Moreover, access to necessary training or resources to implement these kinds of programs is often lacking (Remold et al., 2016). This is especially true for librarians working in small-town or rural libraries.
In this article, we describe a multiyear project in which we first engaged in sustained contextual inquiry to better understand the work practices of small-town and rural school and public librarians. We also sought to understand their perceptions in implementing STEM-rich Maker activities, resources that librarians used to facilitating these activities, and challenges that were encountered (Lee et al., 2017).
Our analyses revealed several constraints and affordances within the librarians' work contexts. First, youth patrons typically attended library programs on an inconsistent and drop-in basis. This meant that library Maker activities needed to support a range of skills, commitments, and experiences. Second, the librarians and youth voiced strong preferences for library programs that were informal in nature, not strongly prescriptive or classroom-like, and connected to a variety of youth interests (Lee et al., 2018a). Third, librarians expressed concerns about facilitating a program in which they often lacked deep-content expertise. Fourth, librarians typically supported many kinds of activities and programs. For example, some librarians only offered “leave it on the table” activities for youth during free time (that we call passive programming), whereas others scheduled structured youth activities on a regular basis. Finally, it was imperative that activities be low cost and did not require extensive use of high-end computers, because many small libraries lack such resources.
Through our interviews with librarians, we also found that they often turned to the Internet for information on how to plan Maker programs. However, the librarians noted that discovered resources were often inappropriate or unrealistic for library settings. For example, some resources feature expensive equipment (e.g., three-dimensional printers) and others required extensive technological or coding knowledge. Instead, the librarians wanted practical models that showed realistic images of Maker activities that could unfold in their libraries in attainable and affordable ways.
On the basis of our study of librarian contexts and our resulting knowledge of the nature of their work practices, we then iteratively designed, developed, and tested a suite of online instructional guides. These were intended to help library personnel, who were assigned to teen programming, to implement informal Maker activities. In the section below, we provide examples of the kinds of STEM-rich Maker activities that we supported. We then describe three genres of online instructional guides to support librarian learning and the design guidelines informing them.
In collaboration with several rural librarians in the Rocky Mountain region, we began by selecting several STEM-rich Maker activities that not only fit the constraints identified above, but were also feasible for their library, affordable, and aligned with their vision for their spaces. Example of Maker activities included
To support librarians in learning about STEM-rich Making activities, we designed three genres of online instruction options: (1) program guides, (2) tips and tricks guides, and (3) how-to video tutorials. For each Maker activity, we developed a program guide, unless a wealth of educator guide information was already available online. In this case, a tips and tricks program guide helped direct librarians to available resources that were just applicable to a library setting, along with pictorial examples of library implementations (because most educator support materials assume classroom settings).
Our how-to video tutorials helped convey basic concepts surrounding a specific Maker activity. The videos could also be shown to youth, to serve as another form of instructional support. To date, we have developed how-to video tutorials for e-textiles and paper circuits. These videos are short—less than 3 min long—and demonstrate the basics for a librarian or youth to quickly get started on their own project.
We distilled four design guidelines that informed development of online instructional resources.
We designed our guides to be educative, in that we drew from research on the design of kindergarten–12 curriculum materials that are intended to help teachers learn to effectively adopt and adapt materials to their specific instructional context (Ball and Cohen, 1996; Davis and Krajcik, 2005; Davis et al., 2017; Schneider and Krajcik, 2002). Curriculum materials are intended to act as resources for supporting student learning, but they are also increasingly seen as tools to help educators learn to engage in teaching practices that may be new to them. Educative supports can come in a variety of forms, ranging from supportive websites, to specific annotations in instruction, to forms of layout and visual displays that provide consistent and clear support of best practices.
Because librarians differ in levels of subject matter knowledge, instructional guides were designed to convey “big ideas” behind the Maker activity, with multiple forms of highlighting and representation of subject-matter knowledge. These were summarized with pithy sayings (or “slogans”) that were associated with the various Maker activities, such as “close the loop” and “beware of tears” (see Figure 1). In addition, guides conveyed essential steps for getting started by providing a do-it-yourself guide for youth to follow. For example, Figure 2 shows the use of a paper circuit template with concise step-by-step instructions to complete a simple electronic circuit. Excluded was some technical information, such as how electron flow is the basis of electricity or how conductive thread has limits because of the way in which metal is integrated into thread fibers.
FIG. 1: Slogans for paper circuit Maker program
FIG. 2: Paper circuit do-it-yourself (DIY) guide for youth
Our findings showed that librarians typically prefer instructional materials that could be quickly appraised at a glance (Phillips et al., 2018). They also prefer pictorial examples that showed realistic images of library Maker activities and conveyed a sense of possibility. This was the direct feedback that we received from practicing librarians. We thus designed guides to incorporate these features, and librarians could then customized these examples to specific interests of their participating youth.
To accommodate the different types of library program styles, guides displayed clear, recurring routines that could be used in both librarian-led and passive programs. Figure 3 shows example guides for both types of programs. Online instructional guides also suggested a simple activity structure, consisting of “learn, make, share” sequences for Maker activities (see Figure 3). To help convey this structure, the guides included simplified templates and tips so that youth and librarians could quickly get started on projects.
FIG. 3: Leave it on the table, librarian-run activity examples, and “learn, make, share” model. DIY, Do it yourself
Librarians often design their own programing by adapting already-established programs to fit the needs of their youth and library. Features were included in the instructional guides to show images of various Maker practices and provide links to available resources to support customized implementations of Maker programming (see Figure 4).
FIG. 4: Various resources included in a tips and tricks instructional guide for the Osmo, an interactive augmented reality digital tool for the iPad that converts the user-facing camera into an instrument for detecting action that takes place on a surface in front of the iPad (see playosmo.com for more information)
In addition to the information available in the instructional guides, we curated lists of online resources on our website to further support librarians in customizing programs. For example, we put together shopping lists of supplies required for each instructional guide, with links to best prices. We also included links to other websites and books that were related to various Maker topics if librarians wished to add those to their library collections.
Once we had initial designs, we began iterative cycles of design-based research (Design-Based Research Collective, 2003) to test, revise, and refine the online instructional guides. In the first phase, guide usability and usefulness were examined by conducting user testing with small groups of school and public librarians in rural communities. Librarians used a structured form to provide feedback (see Figure 5). Most feedback addressed ways to improve quality and utility of guide images.
FIG. 5: Librarian feedback form, with responses
The second phase involved observations and interviews of rural librarians during use of the online instructional guides to implement a youth Maker program in their library. We found that participating librarians' enactments closely resembled the pictorial examples of implementation found in the guides, but opportunities for improvement of the guides arose. On the basis of these implementations, we again made revisions to the instructional guides. For example, we added a troubleshooting section to help librarians debug malfunctioning paper circuits (see Figure 6).
FIG. 6: Troubleshooting tips added to paper circuit instructional guide
This article describes our processes and design guidelines for developing and testing a suite of online instructional guides that are designed to support small-town and rural libraries that are learning to implement STEM-rich youth Maker activities. The guides and their accompanying resources are openly and freely available on library-making.usu.edu. Informally, we have seen a positive response to the guides being made available. Librarians have told us that they fill a niche that would otherwise have to be filled with even more of their own research. We envision the guides also being used in library preservice courses as resources for design of sample programs or models that librarians can use to create and share in future professional networks.
As libraries continue to evolve from a place of book collections to spaces and services supporting active learning, librarians too must learn to support a wider range of activities, including Maker activities. Because librarians, in general, have little formal STEM training and limited, if any, prior experience in facilitating Maker programs, resources are needed to support the learning of these new skills. Providing at-a-glance and tips and tricks instructional guides, how-to tutorial videos, and curated resources that are available online and in open-access formats can help to increase librarian confidence and ability to lead these types of Maker programs for youth. We believe that the processes described and the distilled guidelines can also be useful for others who may be developing supports for librarian learning.
This material is based on work supported by the Institute of Museum and Library Services (RE-31-16-0013-16). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the agency. We thank participating librarians and youth patrons.
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