Proposal for a low cost close air support aircraft for the year 2000: The Raptor

The Raptor is a proposed low cost Close Air Support (CAS) aircraft for the U.S. Military. The Raptor incorporates a 'cranked arrow' wing planform, and uses canards instead of a traditional horizontal tail. The Raptor is designed to be capable of responsive delivery of effective ordnance in close proximity to friendly ground forces during the day, night, and 'under the weather' conditions. Details are presented of the Raptor's mission, configuration, performance, stability and control, ground support, manufacturing, and overall cost to permit engineering evaluation of the proposed design. A description of the design process and analysis methods used is also provided

Performance of an R-410A Room Air Conditioner Modified for Use with R-1234ze

This paper presents the results of a senior design project that challenged a team of undergraduate students to reduce the environmental impact of a room air conditioner (RAC) by reducing its energy consumption and/or use of high-GWP refrigerants. Over the course of an academic year, the team was able to investigate, design, model, evaluate, and build a prototype improved RAC. The team began by reviewing literature on approaches that have been proposed to meet or exceed existing energy efficiency and refrigerant selection regulations. Based on these findings and the specified needs of the project sponsor, the team evaluated the appropriateness of different concepts for improving the existing R-410A RAC design and decided to pursue modifications to adapt the unit for R-1234yf. The first step in the redesign process was to develop a thermodynamic model of the existing system. Because very little information was known about the performance of the individual components in the existing RAC, some rough performance estimates were obtained through measurements. The model of the existing system was then modified to provide the same cooling capacity as the original unit but using R-1234yf, and a replacement compressor was selected based on the model results. After the replacement compressor and resized capillary tubes were installed in the RAC, the team was asked to test the prototype unit using R-1234ze instead of R-1234yf. Therefore, the model was modified to predict the cooling capacity of the unit using R-1234ze as the working fluid. The unit was tested using an environmental chamber to simulate the outdoor air conditions and a large room as the indoor environment. Although this setup could not ensure steady-state operation, air temperature measurements indicated that the room temperature did not vary more than 1.5°F over 12 minutes of RAC operation. The cooling capacity calculated based on experimental measurements agreed within 3% of the model predictions. While the team was able to modify the RAC to operate with R-1234ze and was able to predict the unit’s performance with reasonable accuracy, the modifications required a significantly larger compressor and capillary tubes. Therefore, the project clearly illustrated that fitting within the space and weight constraints of window units presents a significant challenge to implementing R-1234ze in RACs

In-house nucleic acid amplification tests for the detection of Mycobacterium tuberculosis in sputum specimens: meta-analysis and meta-regression

BACKGROUND: More than 200 studies related to nucleic acid amplification (NAA) tests to detect Mycobacterium tuberculosis directly from clinical specimens have appeared in the world literature since this technology was first introduced. NAA tests come as either commercial kits or as tests designed by the reporting investigators themselves (in-house tests). In-house tests vary widely in their accuracy, and factors that contribute to heterogeneity in test accuracy are not well characterized. Here, we used meta-analytical methods, including meta-regression, to identify factors related to study design and assay protocols that affect test accuracy in order to identify those factors associated with high estimates of accuracy. RESULTS: By searching multiple databases and sources, we identified 2520 potentially relevant citations, and analyzed 84 separate studies from 65 publications that dealt with in-house NAA tests to detect M. tuberculosis in sputum samples. Sources of heterogeneity in test accuracy estimates were determined by subgroup and meta-regression analyses. Among 84 studies analyzed, the sensitivity and specificity estimates varied widely; sensitivity varied from 9.4% to 100%, and specificity estimates ranged from 5.6% to 100%. In the meta-regression analysis, the use of IS6110 as a target, and the use of nested PCR methods appeared to be significantly associated with higher diagnostic accuracy. CONCLUSION: Estimates of accuracy of in-house NAA tests for tuberculosis are highly heterogeneous. The use of IS6110 as an amplification target, and the use of nested PCR methods appeared to be associated with higher diagnostic accuracy. However, the substantial heterogeneity in both sensitivity and specificity of the in-house NAA tests rendered clinically useful estimates of test accuracy difficult. Future development of NAA-based tests to detect M. tuberculosis from sputum specimens should take into consideration these findings in improving accuracy of in-house NAA tests

Calpain mediates epithelial cell microvillar effacement by enterohemorrhagic Escherichia coli

A member of the attaching and effacing (AE) family of pathogens, enterohemorrhagic Escherichia coli (EHEC) induces dramatic changes to the intestinal cell cytoskeleton, including effacement of microvilli. Effacement by the related pathogen enteropathogenic E. coli (EPEC) requires the activity of the Ca(+2)-dependent host protease, calpain, which participates in a variety of cellular processes, including cell adhesion and motility. We found that EHEC infection results in an increase in epithelial (CaCo-2a) cell calpain activity and that EHEC-induced microvillar effacement was blocked by ectopic expression of calpastatin, an endogenous calpain inhibitor, or by pretreatment of intestinal cells with a cell-penetrating version of calpastatin. In addition, ezrin, a known calpain substrate that links the plasma membrane to axial actin filaments in microvilli, was cleaved in a calpain-dependent manner during EHEC infection and lost from its normal locale within microvilli. Calpain may be a central conduit through which EHEC and other AE pathogens induce enterocyte cytoskeletal remodeling and exert their pathogenic effects

Characteristics of Some Fruiting Plant Species in Northwest Arkansas, and the Avian Assemblages that Feed on Them

Fruits continue to be recognized as an important food source for birds in temperate areas, particularly during the fall migration period. More than 20 species of plants producing fleshy fruits are found in the Arkansas Ozarks. However, only a few of these appear to be important resources for birds during the fall migration period (August - October). Among those are sassafras (Sassafras albidum), gray-backed grape (Vitis cinerea), black cherry (Prunus serotina), hercules club (Araliaspinosa) and pokeweed (Phytolacca americana). Over the past 4 years, we have documented the physical and nutritional characteristics of those fruits and taken observational data on the assemblages of birds eating them. It appears that avian species assemblages feeding on fruits are partially determined by the physical and nutritional contents of those fruits. Sassafras is extremely lipid-rich and higher in caloric content than the other species of fruits. It appears to be eaten almost exclusively by larger birds, perhaps be due to the large size of its fruits, which may exceed gape width of many smaller bird species. Prunus and Vitis are also eaten by a large number of avian species. Phytolacca was eaten only by a small number of primarily resident bird species and often persisted into the winter. Reasons for this pattern are not clear, as it was relatively similar to the other fruits inmost characteristics. Aralia was seen being eaten by only a few species of birds but is less common than the other species, and its small fruits may not be as attractive as those of the other species. Compared to other places in the east, there appear to be a relatively low number of migratory frugivorous birds in northwestern Arkansas. Overall, there were very few species noted at any fruiting plants, and a large proportion of the total assemblage of birds was comprised of resident species

Experimentation of Electrospray Methodology with Carbon Nanotubes

The focus of the research was design, economically building, and testing of an electrospray platform which will be employed to deposit uniform coatings of carbon nanomaterials to large surfaces. Electrospray, also known as electrohydrodynamic spray or e-spray, is a liquid atomization technique that can generate fine droplets to produce coatings with a high degree of uniformity. The carbon nanotubes (CNTs) and graphene dispersions in water are particularly attractive due to their bulk processing, ease of storage, freedom for tuning the concentration, and for their potential applications in biology and aerospace. This Electrospray platform will be used to apply CNT films, with varying quantities of graphene, that will carry a charge across non-conductive surfaces to act as a de-icing element for aircraft and spacecraft structures. This platform will be utilized for coating large area of non-conductive surfaces which will carry a charge across the structure to act as a de-icing element for aircraft and spacecraft structures

The rotational spectrum of the FeD radical in its X4Δ state, measured by far-infrared laser magnetic resonance

Transitions between the spin-rotational levels of the FeD radical in the v = 0level of the X 4Δ ground state have been detected by the technique of laser magnetic resonance at far-infrared wavelengths. Pure-rotational transitions have been observed for the three lowest spin components. Lambda-type doubling is resolved on all the observed transitions; nuclear hyperfine structure is not observed. The energy levels of FeD are strongly affected by the breakdown of the Born–Oppenheimer approximation and cannot be modeled accurately by an effective Hamiltonian. The data are therefore fitted to an empirical formula to yield term values and g-factors for the various spin-rotational levels involved