4,017 research outputs found
Theoretical macroeconomic modelling and qualitative specifications of the bond market
Macroeconomics ; Bonds
Computer-Controlled Programmable Pulse Generator for a JEOL JNM-FT-1A Radio Frequency Amplifier Section of a Nuclear Magnetic Resonance Spectrometer
A microprocessor controlled programmable pulse generator was specifically designed to interface with the JEOL JNM-FT-1 A Radio Frequency (RF) section of a nuclear magnetic resonance (NMR) spectrometer. The programmable pulse generator was programmed and controlled by an IBM compatible computer. Statis rams were utilized as the programmable pulse generator\u27s on board memory which were used to store the pulse sequences. Pulse widths can be programmed from 0.2 microseconds to 14.3 minutes. The JEOL RF section is unique in that it allows the pulse generator to control the phase of the RF transmitted to the NMR probe and whether the sample will be decoupled. These two items set this programmable pulse generator apart from other pulse generators described in the literature and those systems which are commercially available. This programmable pulse generator was constructed to replace the old JEOL thumb wheel controlled pulse generator. Typical 180 degree pulse lengths for the JEOL NMR are approximately 20 microseconds
Willingness to Pay: Referendum Contingent Valuation and Uncertain Project Benefits
This study uses contingent valuation (CV) methods to estimate the benefit of an environmental water quality project of the TietĂŞ River and its tributaries that flow through the SĂŁo Paulo, Brazil, Metropolitan Area (SPMA). This paper demonstrates the range alternative central tendency measures for WTP produced under alternative parametric and nonparametric approaches using data gathered from a recent referendum CV survey that was conducted in Brazil to analyze a large, multi-phase water quality improvement project. It explains why one of the most commonly used measures, the unrestricted mean of the conditional inverse distribution function of WTP, may be less desirable and more computationally intensive than simpler alternatives like the nonparametric mean of the marginal inverse distribution function.Water management, Economics, contingent valuation, econometric models, environmental impact analysis, economic development projects
Aerobrake assembly with minimum Space Station accommodation
The minimum Space Station Freedom accommodations required for initial assembly, repair, and refurbishment of the Lunar aerobrake were investigated. Baseline Space Station Freedom support services were assumed, as well as reasonable earth-to-orbit possibilities. A set of three aerobrake configurations representative of the major themes in aerobraking were developed. Structural assembly concepts, along with on-orbit assembly and refurbishment scenarios were created. The scenarios were exercised to identify required Space Station Freedom accommodations. Finally, important areas for follow-on study were also identified
Wing-Nacelle-Propeller Interference for Wings of Various Spans Force and Pressure-Distribution Tests
Report presents the results of an experimental investigation made in the NACA full-scale wind tunnel to determine the effect of wing span on nacelle-propeller characteristics and, reciprocally, the lateral extent of nacelle and propeller influence on a monoplane wing. The results provide a check on the validity of the previous research on nacelles and propellers with 15-foot-span wings tested in the 20-foot wind tunnel and reported in technical reports 415, 462, 505, 506, and 507
Boas's Changes in Bodily Form: The Immigrant Study, Cranial Plasticity, and Boas's Physical Anthropology
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65980/1/aa.2003.105.2.326.pd
THE STRUCTURE OF EMPLOYMENT AND UNEMPLOYMENT IN A DECLINING RURAL COMMUNITY
Labor and Human Capital,
The Drosophila genome nexus: a population genomic resource of 623 Drosophila melanogaster genomes, including 197 from a single ancestral range population.
Hundreds of wild-derived Drosophila melanogaster genomes have been published, but rigorous comparisons across data sets are precluded by differences in alignment methodology. The most common approach to reference-based genome assembly is a single round of alignment followed by quality filtering and variant detection. We evaluated variations and extensions of this approach and settled on an assembly strategy that utilizes two alignment programs and incorporates both substitutions and short indels to construct an updated reference for a second round of mapping prior to final variant detection. Utilizing this approach, we reassembled published D. melanogaster population genomic data sets and added unpublished genomes from several sub-Saharan populations. Most notably, we present aligned data from phase 3 of the Drosophila Population Genomics Project (DPGP3), which provides 197 genomes from a single ancestral range population of D. melanogaster (from Zambia). The large sample size, high genetic diversity, and potentially simpler demographic history of the DPGP3 sample will make this a highly valuable resource for fundamental population genetic research. The complete set of assemblies described here, termed the Drosophila Genome Nexus, presently comprises 623 consistently aligned genomes and is publicly available in multiple formats with supporting documentation and bioinformatic tools. This resource will greatly facilitate population genomic analysis in this model species by reducing the methodological differences between data sets
Postsynaptic Modulation of Rectifying Electrical Synaptic Inputs to the LG Escape Command Neuron in Crayfish
The lateral giant (LG) tail-flip escape system of crayfish is organized to provide a massive convergence of mechanosensory inputs onto the LG command neuron through electrical synapses from both mechanosensory afferents and interneurons. We used electrophysiological techniques to show that the connections between three major mechanosensory interneurons and LG rectify, and that their inputs to LG can be reduced by postsynaptic depolarization and increased by postsynaptic hyperpolarization. The mechanosensory afferents and interneurons are excited by sensory nerve shock, and the components of the resulting LG PSP can be similarly modulated by the same postsynaptic potential changes. Because these inputs are all made through electrical synapses, we conclude that they are rectifying connections, as well. To test the physical plausibility of this conclusion, we developed an electrical model of the rectifying connection between a mechanosensory interneuron and LG, and found that it can reproduce all the qualitative features of the orthodromic and antidromic experimental responses. The ability of postsynaptic membrane potential to modulate inputs through rectifying electrical synapses is used in the escape system to enhance LG’s relative sensitivity to novel, phasic stimuli. Postsynaptic depolarization of LG produced by earlier inputs “reverse-biases” the rectifying input synapses and reduces their strength relative to times when LG is at rest
Aerodynamic Analysis of a Generic Fighter with a Chine Fuselage/Delta Wing Configuration Using Delayed Detached-Eddy Simulation
The Modular Transonic Vortex Investigation (MTVI) program at NASA Langley Research Center investigated the transonic characteristics of generic fighter configurations with chined fuselages and delta wings. Previous experiments show that the fuselage and leading edge vortex interactions are detrimental to the vehicle’s aerodynamic characteristics for angles of attack greater than 23º at low angles of sideslip. This is largely due to abrupt asymmetric vortex breakdown, which leads to pronounced pitch-up and significant nonlinearities in lateral stability that could result in roll departure. An improved understanding of the exact origins of this nonlinear behavior would improve future fighter design, and predictive capabilities of such nonlinearities could drastically reduce the cost associated with flight testing new or modified aircraft. The nonlinearities experienced by the MTVI configuration at 30 degrees angle of attack, Reynolds number of 2.68x106, and Mach number of 0.4 are computed using Delayed Detached-Eddy Simulation. Computational predictions of rolling moment compare very well with previous wind tunnel experiments at the same conditions, including the abrupt, nonlinear increase in rolling moment as a function of sideslip angle at small sideslip angles. A detailed investigation of the CFD data confirms that this nonlinearity is due to a rapid change in the flow field structures from symmetric to asymmetric vortex breakdown
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