Photonic crystal thin films of GaAs prepared by atomic layer deposition

Photonic crystal thin films were fabricated via the self-assembly of a lattice of silica spheres on silicon (100) substrates. Progressive infilling of the air spaces within the structure with GaAs was achieved using trimethylgallium and arsine under atomic-layer-deposition conditions. Samples with the highest levels of GaAs infill were subsequently inverted using selective etching. Reflectance spectra are interpreted via the Bragg expression and calculated photonic band structure diagrams. For GaAs infilled and inverted samples, the relative positions of the first and second order Bragg reflections are strongly influenced by the wavelength dependent refractive index

Water Quality in Selected Shallow Wells in Dar es Salaam

Majority of Dar es Salaam residents depend mostly on ground water fortheir domestic use because, they are not connected to the city water supply system,or the supply system is not reliable. Due to widespread use of groundwater (shallowand deep wells), the scientific determination of quality of this mass consumedproduct is essential. In this study the water quality parameters: physical, chemicaland biological contaminants on the shallow wells were investigated around Dar esSalaam City.Except for Total Dissolved Solids (TDS) and Total Hardness, other physicalparameters tested were within the WHO acceptable range. Levels of phosphate insamples from Temeke district ranges from 0.42 – 1.20 ppm, while samples fromIlala ranges from 0.16 – 0.36. Meanwhile chloride levels in samples from Temekeranges between 158.40 – 624.14 ppm and Ilala ranges between 142.34 – 359.52ppm. This could be due to human activities such as small industries and unplanned waste dumping sites close to water source.All water samples were contaminated with both Total Coliform (TC) and Fecal Coliform (FC). The highest TC and FC levels were detected in the sample from Vikunai Village in Temeke municipality (2160/100ml and 67/100ml respectively).This was due to proximity of pit latrines and runoff during rainfall because shallowwells are neither covered nor built up above ground level to create barriers againststorm water inflow.Generally, water from shallow wells in Dar es Salaam City is bacteriologically and chemically contaminated. The source of contamination is on-site waste disposal andpoor hygiene education. It is recommended that water from wells must be treatedprior to consumption in order to prevent potential infections. Residents ought to beprovided with water quality management education so that they could know how totreat, store and maintain the quality of drinking water.Key words: shallow well, phosphate, water quality, nitrate, faecal coliform,chloride

Measuring fitness of Kenyan children with polyparasitic infections using the 20-meter shuttle run test as a morbidity metric.

BACKGROUND: To date, there has been no standardized approach to the assessment of aerobic fitness among children who harbor parasites. In quantifying the disability associated with individual or multiple chronic infections, accurate measures of physical fitness are important metrics. This is because exercise intolerance, as seen with anemia and many other chronic disorders, reflects the body's inability to maintain adequate oxygen supply (VO(2) max) to the motor tissues, which is frequently linked to reduced quality-of-life in terms of physical and job performance. The objective of our study was to examine the associations between polyparasitism, anemia, and reduced fitness in a high risk Kenyan population using novel implementation of the 20-meter shuttle run test (20mSRT), a well-standardized, low-technology physical fitness test. METHODOLOGY/PRINCIPAL FINDINGS: Four villages in coastal Kenya were surveyed during 2009-2010. Children 5-18 years were tested for infection with Schistosoma haematobium (Sh), malaria, filaria, and geohelminth infections by standard methods. After anthropometric and hemoglobin testing, fitness was assessed with the 20 mSRT. The 20 mSRT proved easy to perform, requiring only minimal staff training. Parasitology revealed high prevalence of single and multiple parasitic infections in all villages, with Sh being the most common (25-62%). Anemia prevalence was 45-58%. Using multiply-adjusted linear modeling that accounted for household clustering, decreased aerobic capacity was significantly associated with anemia, stunting, and wasting, with some gender differences. CONCLUSIONS/SIGNIFICANCE: The 20 mSRT, which has excellent correlation with VO(2), is a highly feasible fitness test for low-resource settings. Our results indicate impaired fitness is common in areas endemic for parasites, where, at least in part, low fitness scores are likely to result from anemia and stunting associated with chronic infection. The 20 mSRT should be used as a common metric to quantify physical fitness and compare sub-clinical disability across many different disorders and community settings

Calibration of photomultiplier using UVLED

Detector calibration is very important for the long-term operation. For the purposes of simple and precise calibration, we developed a new portable calibration source using UVLED to calibrate the fluorescence detector of the Telescope Array experiment (TA). The UVLED is light (less than 1 kg) and its setup is quick and easy. Therefore, a single source will be used instead of the calibration sources that TA currently uses. The UVLED emits 369 nm wavelength and ~70 pJ of photons which are calibrated with 5% accuracy us-ing photo-diode. It has a particular unit, which is an internal heater, to keep the temperature constant and avoiding temperature dependency on light yield. The first result of calibration for 24 detectors is xx pho-tons/faced count for 369 nm photons with 6% uncertainty. It is in agreement with the result of the current calibration sources of TA

Thyroxine-Induced Changes in the Development of Neutral Α-Amino Acid Transport Systems of Rat Brain

Transport of representative neutral Α-amino acids was measured in brain slices after injecting thy-roxine into donor rats of various ages from 1 to 23 days old. The hormone did not alter uptake in slices from 1-day-old rats even when treatment was begun on pregnant rats as much as 10 days before delivery. Injecting thy-roxine until age 6 days, however, decreased the activity of transport system A (the major sodium-dependent system in most mammalian cells) and caused appearance of a new transport system used by the model amino acids, 2-aminoisobutyric acid and 2-(methylamino)isobutyric acid. Uptake at 6 days was similar to that found in slices from older, untreated rats (e.g., those 14 days old). These results strongly suggest that one action of thyroxine is to accelerate the development of neutral Α-amino acid transport systems of brain over the first six days after birth. Thyroxine treatment of rats from birth to age 14 days also appears to increase the activities of both system A and the second transport system used by the two model amino acids in brains from 14-day-old rats.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66252/1/j.1471-4159.1984.tb02781.x.pd

Developmental Changes in the Neutral Α-Amino Acid Transport Systems of Rat Brain Over the First Three Weeks After Birth

Transport of seven different amino acids into brain slices increased as donor rats aged from 1 to 6 days. Uptakes of 2-aminoisobutyric acid, 2-(methyl-amino)isobutyric acid, and L-alanine then decreased by day 14, while uptakes of other amino acids continued to increase or remained fairly constant. Neutral Α-amino acid transport systems were characterized by measuring inhibition of uptakes and kinetics for representative amino acids at different ages. Results indicate that 2-ami-noisobutyrate and 2-(methylamino)isobutyrate used only one (and the same) system in brain slices from 6-day-old rats, with characteristics of system A (the major sodium-dependent system in most mammalian cells). They used at least two systems at ages 1, 14, and 23 days, but, of these, only at 1 day did they use the same systems in the same proportions. Alanine and leucine used more than one system at all four ages, and somewhat different combinations than used by each other or by 2-aminoisobu-tyrate or 2-(methylamino)isobutyrate. Their transport characteristics showed they used mostly system ASC (a sodium-dependent system distinguished from A) and/or system L (sodium-independent). We conclude that system A increases as the brain ages from 1 to 6 days and declines thereafter. System L probably increases with aging from 1 to 23 days.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66235/1/j.1471-4159.1984.tb02780.x.pd

Angoff anchor statements: setting a flawed gold standard?

http://www.mededpublish.org/manuscripts/120