1,118 research outputs found
Use of the MATRIXx Integrated Toolkit on the Microwave Anisotropy Probe Attitude Control System
Recent advances in analytical software tools allow the analysis, simulation, flight code, and documentation of an algorithm to be generated from a single source, all within one integrated analytical design package. NASA's Microwave Anisotropy Probe project has used one such package, Integrated Systems' MATRIXx suite, in the design of the spacecraft's Attitude Control System. The project's experience with the linear analysis, simulation, code generation, and documentation tools will be presented and compared with more traditional development tools. In particular, the quality of the flight software generated will be examined in detail. Finally, lessons learned on each of the tools will be shared
Reactive Oxygen Species Production and Brugia Pahangi Survivorship in Aedes polynesiensis with Artificial Wolbachia Infection Types
Heterologous transinfection with the endosymbiotic bacterium Wolbachia has been shown previously to induce pathogen interference phenotypes in mosquito hosts. Here we examine an artificially infected strain of Aedes polynesiensis, the primary vector of Wuchereria bancrofti, which is the causative agent of Lymphatic filariasis (LF) throughout much of the South Pacific. Embryonic microinjection was used to transfer the wAlbB infection from Aedes albopictus into an aposymbiotic strain of Ae. polynesiensis. The resulting strain (designated MTB ) experiences a stable artificial infection with high maternal inheritance. Reciprocal crosses of MTB with naturally infected wild-type Ae. polynesiensis demonstrate strong bidirectional incompatibility. Levels of reactive oxygen species (ROS) in the MTB strain differ significantly relative to that of the wild-type, indicating an impaired ability to regulate oxidative stress. Following a challenge with Brugia pahangi, the number of filarial worms achieving the infective stage is significantly reduced in MTB as compared to the naturally infected and aposymbiotic strains. Survivorship of MTB differed significantly from that of the wild-type, with an interactive effect between survivorship and blood feeding. The results demonstrate a direct correlation between decreased ROS levels and decreased survival of adult female Aedes polynesiensis. The results are discussed in relation to the interaction of Wolbachia with ROS production and antioxidant expression, iron homeostasis and the insect immune system. We discuss the potential applied use of the MTB strain for impacting Ae. polynesiensis populations and strategies for reducing LF incidence in the South Pacific
Geology of the Fire Clay Coal in Part of the Eastern Kentucky Coal Field
Coal beds mined in Kentucky often are not laterally continuous in thickness, quality, or roof condition. Regional and local variation is common. Because thickness, quality, and roof conditions are the result of geologic processes that were active when the coal was deposited as a peat swamp, a better understanding of the relationships between geology and major coal resources can aid in identifying geologic trends, which can be extrapolated beyond areas of present mining. The focus of this study is on the Fire Clay (Hazard No. 4) coal, one of the leading producers in the Eastern Kentucky Coal Field with 20 million short tons of annual production. More than 3,800 thickness measurements, highwall and outcrop descriptions, borehole and geophysical-log descriptions, and proximate analyses from 97 localities were used in conjunction with previous palynologic and petrographic studies to investigate the geology of the Fire Clay coal in a 15-quadrangle area of the Eastern Kentucky Coal Field.
The Fire Clay coal is commonly separated into two distinct layers or benches by a flint-clay and shale parting called the “jackrock parting” by miners. Maps of coal benches above and below the parting show that the lower bench is limited in extent and variable in thickness. In contrast, the coal above the jackrock parting occurs across most of the study area and is characterized by rectangular patterns of coal thickness.
Multiple coal benches resulted from the accumulation of multiple peat deposits, each with different characteristics. The lower bench of the coal was deposited when a peat accumulated above an irregular topographic surface. Because the peat was being deposited at or below the water table, it was often flooded by sediment from lateral sources, resulting in moderate to locally high ash yields. This peat was drowned and then covered by volcanic ash, which formed the flint clay in the jackrock parting. The upper coal bench accumulated above the ash deposit, after irregularities in the topography had been filled. The relatively flat surface allowed the swamps to spread outward and dome upward above the water table in some areas. Doming of the peat resulted in areas of coal with generally low ash yields and sulfur contents. Sharp, angular changes in the upper coal bench are inferred to represent subtle fault influence on upper peat accumulation.
The upper peat was buried by a series of river channels, which were bounded by levees, flood plains, and elongate bays. Several of the rivers eroded through the Fire Clay peats, forming cutouts in the coal. These cutouts often follow orientations similar to the angular trends of coal thinning, suggesting a relationship that can be extended beyond the present limits of mining. Also, additional peat swamps accumulated above the levees and flood plains bounding the channels. Along the thinning margins of these deposits, the peats came near or merged with the top of the Fire Clay coal, resulting in local areas of increased coal thickness.
Rider coal benches exhibit high to moderate sulfur contents and ash yields, so that although they may increase coal thickness, total coal quality generally decreases where riders combine with the Fire Clay coal
Evaluating PCR-Based Detection of Salmonella Typhi and Paratyphi A in the Environment as an Enteric Fever Surveillance Tool.
With prequalification of a typhoid conjugate vaccine by the World Health Organization, countries are deciding whether and at what geographic scale to provide the vaccine. Optimal local data to clarify typhoid risk are expensive and often unavailable. To determine whether quantitative polymerase chain reaction (qPCR) can be used as a tool to detect typhoidal Salmonella DNA in the environment and approximate the burden of enteric fever, we tested water samples from urban Dhaka, where enteric fever burden is high, and rural Mirzapur, where enteric fever burden is low and sporadic. Sixty-six percent (38/59) of the water sources of Dhaka were contaminated with typhoidal Salmonella DNA, in contrast to none of 33 samples of Mirzapur. If these results can be replicated in larger scale in Bangladesh and other enteric fever endemic areas, drinking water testing could become a low-cost approach to determine the presence of typhoidal Salmonella in the environment that can, in turn, guide informed-design of blood culture-based surveillance and thus assist policy decisions on investing to control typhoid
Integrating facility-based surveillance with healthcare utilization surveys to estimate enteric fever incidence: Methods and challenges
Cohort studies and facility-based sentinel surveillance are common approaches to characterizing infectious disease burden, but present trade-offs; cohort studies are resource-intensive and may alter disease natural history, while sentinel surveillance underestimates incidence in the population. Hybrid surveillance, whereby facility-based surveillance is paired with a community-based healthcare utilization assessment, represents an alternative approach to generating population-based disease incidence estimates with moderate resource investments. Here, we discuss this method in the context of the Surveillance for Enteric Fever in Asia Project (SEAP) study. We describe how data are collected and utilized to adjust enteric fever incidence for blood culture sensitivity, facility-based enrollment, and healthcare seeking, incorporating uncertainty in these parameters in the uncertainty around incidence estimates. We illustrate how selection of surveillance sites and their coverage may influence precision and bias, and we identify approaches in the study design and analysis to minimize and control for these biases. Rigorously designed hybrid surveillance systems can be an efficient approach to generating population-based incidence estimates for infectious diseases
Available Resources of the Fire Clay Coal in Part of the Eastern Kentucky Coal Field
Available resources for the Fire Clay coal were calculated for a 15-quadrangle area in the Eastern Kentucky Coal Field. Original coal resources were estimated to be 1.8 billion tons (BT). Coal mined or lost in mining was estimated at 449 million tons (MT), leaving 1.3 BT of remaining Fire Clay resources in the study area. Of the remaining resources, 400 MT is restricted from mining, primarily because the coal is less than 28 in. thick, normally considered too thin to mine underground using present technology. The total coal available for mining in the study area is 911 MT, or 52 percent of the original resource. Of the 911 MT, 14.9 percent is thicker than 42 in., and only 6.1 percent is accessible by surface-mining methods. The largest block of available coal is in the Leatherwood quadrangle, is less than 42 in. thick, and mostly occurs below drainage
Available Coal Resources of the Booneville 7.5–Minute Quadrangle, Owsley County, Kentucky
The Booneville Quadrangle lies within the Southwestern Reserve District of the Eastern Kentucky Coal Field. Six coal beds in the quadrangle have been commercially developed, mainly by surface mining methods, and comprise the basis of this Coal Availability Study. These beds are, in descending stratigraphic order, Copland, Whitesburg, Amburgy, Upper Elkhorn No. 3, Jellico and Manchester. A computerized Geographic Information System (GRASS) was used to calculate estimates of original, mined-out and remaining resources, restrictions to mining and available resources
The Taf14 YEATS domain is a reader of histone crotonylation
The discovery of new histone modifications is unfolding at startling rates, however, the identification of effectors capable of interpreting these modifications has lagged behind. Here we report the YEATS domain as an effective reader of histone lysine crotonylation – an epigenetic signature associated with active transcription. We show that the Taf14 YEATS domain engages crotonyllysine via a unique π-π-π-stacking mechanism and that other YEATS domains have crotonyllysine binding activity
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