190 research outputs found

    Nondestructive leak testing

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    Method provides opportunity to effect repairs without compromising integrity of enclosed circuitry or mechanism by loss of atmosphere or by ingestion of foreign matter or gas. It is possible to detect leaks in modules which are sealed while fully evacuated, partially evacuated, or containing some form of gas

    Handtool facilitates extraction of circuit modules

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    Compact handtool extracts electronic modules from circuit board socket. It is used on modules that have four small notches in the base of the plastic housing

    The design and fabrication of microstrip omnidirectional array antennas for aerospace applications

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    A microstrip antenna design concept was developed that will provide quasi-omnidirectional radiation pattern characteristics about cylindrical and conical aerospace structures. L-band and S-band antenna arrays were designed, fabricated, and, in some cases, flight tested for rocket, satellite, and aircraft drone applications. Each type of array design is discussed along with a thermal cover design that was required for the sounding rocket applications

    Property Tax Lids and the Effect on Kansas

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    Cross sectional time series data in a partial adjustment model examine local government behavior under an aggregate property tax levy limit and under Truth in Taxation in Kansas. Results indicate that the aggregate levy limit would have continued to restrict property tax revenue and spending had it not been replaced.Public Economics,

    System for measuring passenger reaction to transportation-vehicle vibration

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    Equipment is capable of measuring frequencies from 0 to 50 Hz and is portable, light, inexpensive, and easily adaptable to field operations. System could be used in situations where it is necessary to record simultaneously subject response to other types of physical measurement or stimuli, such as temperature, noise, or pressure

    The Impact of the Workforce Investment Act on Technical School and Community College Enrollment in Louisiana

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    Abstract. Rural Louisiana has many of the same problems as other rural states: population decline, unemployment, poverty. At the same time, Louisiana has an extensive array of community colleges, universities and technical schools through which workers can get an education. Workforce development -employee training, linking schools and employers, curriculum to match desired skills -has emerged as a popular tool for rural economic growth. Critics say that the Workforce Investment Act (WIA) and welfare reform have made training for the unemployed and economically disadvantaged more difficult to acquire and more difficult to provide

    The Impact of Tillage System for Small-Grain Pasture Establishment on the Performance of Growing Beef Calves in Arkansas

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    In the United States, governmental regulations mandate the improvement of farming practices to improve environmental quality. There is a requirement to reduce the siltation of waterways, soil carbon losses, and nutrient runoff along the Mississippi River Delta. The use of small-grain forages by grazing cattle offers real opportunities to produce high-quality forage for cattle production during the winter and spring months. No-till and reduced tillage practices developed primarily for grain production may offer environmental and economic solutions for both grain farmers and cattle producers. Producers are slow to adopt conservation tillage practices because of a perceived risk of reduced production. The objective of this project was to compare conventional tillage to reduced tillage and no-till systems for production of small-grain forage for grazing livestock

    Computational Modeling of Supramolecular Metallo-organic Cages-Challenges and Opportunities

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    [Image: see text] Self-assembled metallo-organic cages have emerged as promising biomimetic platforms that can encapsulate whole substrates akin to an enzyme active site. Extensive experimental work has enabled access to a variety of structures, with a few notable examples showing catalytic behavior. However, computational investigations of metallo-organic cages are scarce, not least due to the challenges associated with their modeling and the lack of accurate and efficient protocols to evaluate these systems. In this review, we discuss key molecular principles governing the design of functional metallo-organic cages, from the assembly of building blocks through binding and catalysis. For each of these processes, computational protocols will be reviewed, considering their inherent strengths and weaknesses. We will demonstrate that while each approach may have its own specific pitfalls, they can be a powerful tool for rationalizing experimental observables and to guide synthetic efforts. To illustrate this point, we present several examples where modeling has helped to elucidate fundamental principles behind molecular recognition and reactivity. We highlight the importance of combining computational and experimental efforts to speed up supramolecular catalyst design while reducing time and resources

    Artifacts and Pheromone Blends from Nezara spp. and Other Stink Bugs (Heteroptera: Pentatomidae)

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    Isomeric com pounds reportedly released by mature males o f Nezara viridula as attractants for conspecific females are evidently artifacts formed by dimerization o f (£)-4-oxo-2-hexenal. Additional analyses o f the male-specific volatiles from Italian, Australian, Brazilian, and Japanese populations o f N. viridula verify that at least two distinctive pheromone strains exist, but an active synthetic pheromone has not yet been developed. Analyses o f volatiles from N. antennata and Acrosternum aseadum males are also reported showing that the native Japanese Nezara sp., and species in the sister genus Acrosternum, produce species-specific blends based on the same com pounds as N. viridula: (Z)-a-bisabolene (l-m ethyl-4-(l,5-im ethyl-(Z )-l,4-hexadienyl)-cyclohexene), and trans- and cis- 1,2-epoxides o f (Z)-a-bisabolene. The trans-/cis- I,2-epoxide ratio o f N. antennata is within the range found for most N. viridula populations, but the blend from Japanese N. viridula males deviates radically from those o f other conspecific populations
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