178 research outputs found
Global surface slopes and roughness of the Moon from the Lunar Orbiter Laser Altimeter
The acquisition of new global elevation data from the Lunar Orbiter Laser Altimeter, carried on the Lunar Reconnaissance Orbiter, permits quantification of the surface roughness properties of the Moon at unprecedented scales and resolution. We map lunar surface roughness using a range of parameters: median absolute slope, both directional (along-track) and bidirectional (in two dimensions); median differential slope; and Hurst exponent, over baselines ranging from ~17 m to ~2.7 km. We find that the lunar highlands and the mare plains show vastly different roughness properties, with subtler variations within mare and highlands. Most of the surface exhibits fractal-like behavior, with a single or two different Hurst exponents over the given baseline range; when a transition exists, it typically occurs near the 1 km baseline, indicating a significant characteristic spatial scale for competing surface processes. The Hurst exponent is high within the lunar highlands, with a median value of 0.95, and lower in the maria (with a median value of 0.76). The median differential slope is a powerful tool for discriminating between roughness units and is useful in characterizing, among other things, the ejecta surrounding large basins, particularly Orientale, as well as the ray systems surrounding young, Copernican-age craters. In addition, it allows a quantitative exploration on mare surfaces of the evolution of surface roughness with age
Breast specific gamma imaging: Role in evaluation of breast disease
Although mammography is the gold standard for screening for breast cancer, 10 to 15% of lesions are missed, and this is higher with dense breasts. Alternative diagnostic modalities are being developed. One of these, breast specific gamma imaging (BSGI), which is not effected by dense tissue, utilizes the increased metabolic activity of tumors to localize and distinguish benign from malignant processes in the breast. The test can be used for screening and diagnostic purposes
Measurements and modeling of optical-equivalent snow grain sizes under arctic low-sun conditions
The size and shape of snow grains directly impacts the reflection by a snowpack. In this article, different approaches to retrieve the optical-equivalent snow grain size (r) or, alternatively, the specific surface area (SSA) using satellite, airborne, and ground-based observations are compared and used to evaluate ICON-ART (ICOsahedral Nonhydrostatic—Aerosols and Reactive Trace gases) simulations. The retrieval methods are based on optical measurements and rely on the r-dependent absorption of solar radiation in snow. The measurement data were taken during a three-week campaign that was conducted in the North of Greenland in March/April 2018, such that the retrieval methods and radiation measurements are affected by enhanced uncertainties under these low-Sun conditions. An adjusted airborne retrieval method is applied which uses the albedo at 1700 nm wavelength and combines an atmospheric and snow radiative transfer model to account for the direct-to-global fraction of the solar radiation incident on the snow. From this approach, we achieved a significantly improved uncertainty (<25%) and a reduced effect of atmospheric masking compared to the previous method. Ground-based in situ measurements indicated an increase of r of 15 µm within a five-day period after a snowfall event which is small compared to previous observations under similar temperature regimes. ICON-ART captured the observed change of r during snowfall events, but systematically overestimated the subsequent snow grain growth by about 100%. Adjusting the growth rate factor to 0.012 µm s minimized the difference between model and observations. Satellite-based and airborne retrieval methods showed higher r over sea ice (<300 µm) than over land surfaces (<100 µm) which was reduced by data filtering of surface roughness features. Moderate-Resolution Imaging Spectroradiometer (MODIS) retrievals revealed a large spread within a series of subsequent individual overpasses, indicating their limitations in observing the snow grain size evolution in early spring conditions with low Sun
Resposta sorológica de adultos à vacinação contra a rubéola
The effect of Wistar RA 27/3 live attenuated rubella virus vaccine, given subcutaneously, was evaluated in 30 susceptible female schoolteachers aged 20 to 35 years and over, from the city of São Paulo, Brazil. The serum samples, to be tested for hemagglutination-inhibiting (HI) and complement fixing (CF) antibodies, were collected 10, 30, 90 and 180 days after vaccination. Of the 30 susceptible adults who received the Wistar RA 27/3 vaccine, 96,6% showed seroconversion in the HI and CF tests. No unusual reactions occured.Foi estudada a resposta sorológica à vacinação contra a rubéola, por via subcutânea, com a cepa vacinal viva atenuada Wistar RA 27/3, num grupo de 30 professoras da rede municipal de ensino de São Paulo. Foram escolhidos, como participantes do grupo, indivíduos destituídos de imunidade contra a rubéola, tendo as dosagens de anticorpos inibidores da hemaglutinação e fixadores do complemento sido feitas em amostras de soro colhidas 10, 30, 90 e 180 dias após a vacinação. Tanto nas provas de inibição da hemaglutinação, como fixação do complemento, observou-se uma soro-conversão de 96,6%. Não se observaram quaisquer relações vacinais no grupo em estudo
Identificação por contraimunoeletroforese de rotavirus em casos de diarréia infantil
The faecal samples of 162 children with acute diarrhea were tested by counterimmunoelectrophoresis in order to detect rotaviruses. In 72.7%, 77.7% and 66.6% of samples from children of different age groups, varying from 6 to 8 months to 1 year or older, a positive result was found.Os resultados obtidos na identificação de rotavirus, usando a técnica da contraimunoeletroforese, com 162 amostras de feses de crianças com quadros diarréicos agudos, mostram uma distribuição percentual de positividade de 72,7%, 77,7% e 66,6% em diferentes grupos etários de 6 a 8 meses até um ano de idade
A reação de fixação do complemento na identificação de rotavírus humano
Após a eliminação da anticomplementaridade, foi utilizada a reação de fixação do complemento na identificação de rotavírus em 134 amostras de fezes de crianças até um ano de idade, com quadros diarréicos agudos. A percentagem total de positividade foi de 28,7% com percentagens mais elevadas de casos positivos nos grupos etários de 6 meses a 1 ano de idade.After eliminating the anticomplementarity of the fecal extracts, complement fixation was used to detect human rotavirus in the stools of 35 (28.7%) out of 122 one-to twelve-month-old children with acute gastroenteritis. Infection was nigher in the 6-to 12-month-old children
A meta-analysis of long-term effects of conservation agriculture on maize grain yield under rain-fed conditions
Conservation agriculture involves reduced tillage, permanent soil cover and crop rotations to enhance soil fertility and to supply food from a dwindling land resource. Recently, conservation agriculture has been promoted in Southern Africa, mainly for maize-based farming systems. However, maize yields under rain-fed conditions are often variable. There is therefore a need to identify factors that influence crop yield under conservation agriculture and rain-fed conditions. Here, we studied maize grain yield data from experiments lasting 5 years and more under rain-fed conditions. We assessed the effect of long-term tillage and residue retention on maize grain yield under contrasting soil textures, nitrogen input and climate. Yield variability was measured by stability analysis. Our results show an increase in maize yield over time with conservation agriculture practices that include rotation and high input use in low rainfall areas. But we observed no difference in system stability under those conditions. We observed a strong relationship between maize grain yield and annual rainfall. Our meta-analysis gave the following findings: (1) 92% of the data show that mulch cover in high rainfall areas leads to lower yields due to waterlogging; (2) 85% of data show that soil texture is important in the temporal development of conservation agriculture effects, improved yields are likely on well-drained soils; (3) 73% of the data show that conservation agriculture practices require high inputs especially N for improved yield; (4) 63% of data show that increased yields are obtained with rotation but calculations often do not include the variations in rainfall within and between seasons; (5) 56% of the data show that reduced tillage with no mulch cover leads to lower yields in semi-arid areas; and (6) when adequate fertiliser is available, rainfall is the most important determinant of yield in southern Africa. It is clear from our results that conservation agriculture needs to be targeted and adapted to specific biophysical conditions for improved impact
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