41,553 research outputs found
New secondary batteries utilizing electronically conductive polymer cathodes
The objectives are to optimize the transport rates in electronically conductive polypyrrole films by controlling the morphology of the film and to assess the utility of these films as cathodes in a lithium/polypyrrole secondary battery. During this research period, a better understanding was gained of the fundamental electrochemical switching processes within the polypyrrole film. Three publications were submitted based on the work completed
SSF loads and controllability during assembly
The Orbiter Primary Reaction Control System (PRCS) pulse width and firing frequency is restricted to prevent excessive loads in the Space Station Freedom (SSF). The feasibility of using the SSF Control Moment Gyros (CMG) as a secondary controller for load relief is evaluated. The studies revealed the CMG not only reduced loads but were useful for other SSF functions: vibration suppression and modal excitation. Vibration suppression lowers the g level for the SSF micro-g experiments and damps the low frequency oscillations that cause crew sickness. Modal excitation could be used for the modal identification experiment and health monitoring. The CMG's reduced the peak loads and damped the vibrations. They were found to be an effective multi-purpose ancillary device for SSF operation
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Analysis of the visual spatiotemporal properties of American Sign Language.
Careful measurements of the temporal dynamics of speech have provided important insights into phonetic properties of spoken languages, which are important for understanding auditory perception. By contrast, analytic quantification of the visual properties of signed languages is still largely uncharted. Exposure to sign language is a unique experience that could shape and modify low-level visual processing for those who use it regularly (i.e., what we refer to as the Enhanced Exposure Hypothesis). The purpose of the current study was to characterize the visual spatiotemporal properties of American Sign Language (ASL) so that future studies can test the enhanced exposure hypothesis in signers, with the prediction that altered vision should be observed within, more so than outside, the range of properties found in ASL. Using an ultrasonic motion tracking system, we recorded the hand position in 3-dimensional space over time during sign language production of signs, sentences, and narratives. From these data, we calculated several metrics: hand position and eccentricity in space and hand motion speed. For individual signs, we also measured total distance travelled by the dominant hand and total duration of each sign. These metrics were found to fall within a selective range, suggesting that exposure to signs is a specific and unique visual experience, which might alter visual perceptual abilities in signers for visual information within the experienced range, even for non-language stimuli
A Program for the Collection, Storage, and Analysis of Baseline Environmental Data for Cook Inlet, Alaska
The scope of this report is to provide a general, yet comprehensive,
description of the Cook Inlet System which will serve as a
basis for understanding the interrelated natural and man-made factors
governing its future; to present a program of field research studies
for the estuarine environment that will describe the existing state of
the Inlet with respect to the water quality and biota; to provide a
framework whereby the program of studies can be evaluated and redirected
in light of the preliminary results; and, to provide a method of storing
and analyzing the data from the investigations so that it can be made
available to interested parties in the most efficient manner possible.This report was prepared by the Institute of Water Resources of the
University of Alaska for the Alaska Water Laboratory, Federal Water
Pollution Control Administration under Contract No. 14-12-449
Implementing direct consumption taxes in developing countries
This report examines the possibility of using a direct tax on consumption as a replacement for an existing income tax within the context of a developing country. The structural differences between income and consumption taxes are described, and some simple examples are used to illustrate the basic differences in the taxation of businesses and individuals under the two approaches. The report includesa brief survey of the extensive literature on the choice between income and consumption as the basis for a system of direct taxation. After a detailed discussion of the choice between cash flow and tax prepayment treatment at the individual level under a direct consumption tax, the analysis concludes that for simplicity reasons the individual tax prepayment approach is the more appropriate one in the developing country context. The report then describes the structure and implementation of such a direct consumption tax. The discussion includes an examination of international and transitional issues, and also comments on the desirability and feasibility of supplementary wealth taxes and taxation on a presumptive basis.Environmental Economics&Policies,Economic Theory&Research,Public Sector Economics&Finance,Banks&Banking Reform,International Terrorism&Counterterrorism
Selection Mapping Identifies Loci Underpinning Autumn Dormancy in Alfalfa (Medicago sativa).
Autumn dormancy in alfalfa (Medicago sativa) is associated with agronomically important traits including regrowth rate, maturity, and winter survival. Historical recurrent selection experiments have been able to manipulate the dormancy response. We hypothesized that artificial selection for dormancy phenotypes in these experiments had altered allele frequencies of dormancy-related genes. Here, we follow this hypothesis and analyze allele frequency changes using genome-wide polymorphisms in the pre- and postselection populations from one historical selection experiment. We screened the nondormant cultivar CUF 101 and populations developed by three cycles of recurrent phenotypic selection for taller and shorter plants in autumn with markers derived from genotyping-by-sequencing (GBS). We validated the robustness of our GBS-derived allele frequency estimates using an empirical approach. Our results suggest that selection mapping is a powerful means of identifying genomic regions associated with traits, and that it can be exploited to provide regions on which to focus further mapping and cloning projects
Computer simulation of preflight blood volume reduction as a countermeasure to fluid shifts in space flight
Fluid shifts in weightlessness may cause a central volume expansion, activating reflexes to reduce the blood volume. Computer simulation was used to test the hypothesis that preadaptation of the blood volume prior to exposure to weightlessness could counteract the central volume expansion due to fluid shifts and thereby attenuate the circulatory and renal responses resulting in large losses of fluid from body water compartments. The Guyton Model of Fluid, Electrolyte, and Circulatory Regulation was modified to simulate the six degree head down tilt that is frequently use as an experimental analog of weightlessness in bedrest studies. Simulation results show that preadaptation of the blood volume by a procedure resembling a blood donation immediately before head down bedrest is beneficial in damping the physiologic responses to fluid shifts and reducing body fluid losses. After ten hours of head down tilt, blood volume after preadaptation is higher than control for 20 to 30 days of bedrest. Preadaptation also produces potentially beneficial higher extracellular volume and total body water for 20 to 30 days of bedrest
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