925 research outputs found
Ulysses
The DSN (Deep Space Network) mission support requirements for Ulysses are summarized. The primary goal of the Ulysses mission is to explore the Sun, its environment, and possible links between solar variability and terrestrial weather and climate. The Ulysses spacecraft will be injected into an interplanetary orbit toward Jupiter after which the spacecraft travels in a heliocentric, out-of-ecliptic orbit with high heliographic inclination. The Ulysses mission objectives are outlined and the DSN support requirements are defined through the presentation of tables and narratives describing the spacecraft flight profile; DSN support coverage; frequency assignments; support parameters for telemetry, command and support systems; and tracking support responsibility
Thermal Infrared Multispectral Scanner (TIMS): An investigator's guide to TIMS data
The Thermal Infrared Multispectral Scanner (TIMS) is a NASA aircraft scanner providing six channel spectral capability in the thermal infrared region of the electromagnetic spectrum. Operating in the atmospheric window region (8 to 12 micrometers) with a channel sensitivity of approximately 0.1 C, TIMS may be used whenever an accurate measure of the Earth's surface is needed. A description of this scanner is provided as well as a discussion of data acquisition and reduction
Nongame Birds, Small Mammals, Reptiles, Fishes: Sand Lake National Wildlife Refuge, 1995-1996
The goal of this study was to conduct a nongame vertebrate survey at SLNWR by primary habitat types, with emphasis placed on nongame breeding birds and small mammals . Specific objectives were to determine: 1) avian and mammalian species composition by primary habitat types with special emphasis on nongame/neotropical avian species and nongame small mammals, 2) the presence of other vertebrate species (amphibians, reptiles , and fishes) by primary habitat type, 3) present vertebrate biota occurrence, as compared to pre-1940 occurence as found in the literature and other records or sources, 4) significant changes in habitat and/ or vegetation on SLNWR, based on current and historical literature and refuge files, and 5) to make recommendations for preserving/ enhancing populations of nongame vertebrate species on SLNWR
Classroom and the Cloze Procedure: Interaction in Imagery
The paper will give the background research concerning cloze techniques, detail the steps teachers would follow to use Interactive Cloze, report behavioral observations within the classroom setting, and indicate direction for research into the efficacy of this procedure
Tracking and data systems support for the Helios project. Volume 2: DSN support of Project Helios April 1975 - May 1976
Deep Space Network activities in the development of the Helios B mission from planning through entry of Helios 2 into first superior conjunction (end of Mission Phase II) are summarized. Network operational support activities for Helios 1 from first superior conjunction through entry into third superior conjunction are included
A Vibrio cholerae Classical TcpA Amino Acid Sequence Induces Protective Antibody That Binds an Area Hypothesized To Be Important for Toxin-Coregulated Pilus Structure
Vibrio cholerae is a gram-negative bacterium that has been associated with cholera pandemics since the early 1800s. Whole-cell, killed, and live-attenuated oral cholera vaccines are in use. We and others have focused on the development of a subunit cholera vaccine that features standardized epitopes from various V. cholerae macromolecules that are known to induce protective antibody responses. TcpA protein is assembled into toxin-coregulated pilus (TCP), a type IVb pilus required for V. cholerae colonization, and thus is a strong candidate for a cholera subunit vaccine. Polypeptides (24 to 26 amino acids) in TcpA that can induce protective antibody responses have been reported, but further characterization of their amino acid targets relative to tertiary or quaternary TCP structures has not been done. We report a refinement of the TcpA sequences that can induce protective antibody. One sequence, TcpA 15 (residues 170 to 183), induces antibodies that bind linear TcpA in a Western blot as well as weakly bind soluble TcpA in solution. These antibodies bind assembled pili at high density and provide 80 to 100% protection in the infant mouse protection assay. This is in sharp contrast to other anti-TcpA peptide sera (TcpA 11, TcpA 13, and TcpA 17) that bind very strongly in Western blot and solution assays yet do not provide protection or effectively bind TCP, as evidenced by immunoelectron microscopy. The sequences of TcpA 15 that induce protective antibody were localized on a model of assembled TCP. These sequences are centered on a site that is predicted to be important for TCP structure
Functional Impact of a Cancer-Related Variant in Human Δ\u3csup\u3e1\u3c/sup\u3e‑Pyrroline-5-Carboxylate Reductase 1
Pyrroline-5-carboxylate reductase (PYCR) is a proline biosynthetic enzyme that catalyzes the NAD(P)H-dependent reduction of Δ1-pyrroline-5-carboxylate (P5C) to proline. Humans have three PYCR isoforms, with PYCR1 often upregulated in different types of cancers. Here, we studied the biochemical and structural properties of the Thr171Met variant of PYCR1, which is found in patients with malignant melanoma and lung adenocarcinoma. Although PYCR1 is strongly associated with cancer progression, characterization of a PYCR1 variant in cancer patients has not yet been reported. Thr171 is conserved in all three PYCR isozymes and is located near the P5C substrate binding site. We found that the amino acid replacement does not affect thermostability but has a profound effect on PYCR1 catalytic activity. The kcat of the PYCR1 variant T171M is 100- to 200-fold lower than wild-type PYCR1 when P5C is the variable substrate, and 10- to 25-fold lower when NAD(P)H is varied. A 1.84 Å resolution X-ray crystal structure of T171M reveals that the Met side chain invades the P5C substrate binding site, suggesting that the catalytic defect is due to steric clash preventing P5C from achieving the optimal pose for hydride transfer from NAD(P)H. These results suggest that any impact on PYCR1 function associated with T171M in cancer does not derive from increased catalytic activity
Parabolic stable surfaces with constant mean curvature
We prove that if u is a bounded smooth function in the kernel of a
nonnegative Schrodinger operator on a parabolic Riemannian
manifold M, then u is either identically zero or it has no zeros on M, and the
linear space of such functions is 1-dimensional. We obtain consequences for
orientable, complete stable surfaces with constant mean curvature
in homogeneous spaces with four
dimensional isometry group. For instance, if M is an orientable, parabolic,
complete immersed surface with constant mean curvature H in
, then and if equality holds, then
M is either an entire graph or a vertical horocylinder.Comment: 15 pages, 1 figure. Minor changes have been incorporated (exchange
finite capacity by parabolicity, and simplify the proof of Theorem 1)
CEO pay, shareholder returns, and accounting profits
We assess the impact on CEO pay (including salary, cash bonus, and benefits in kind) of changes in both accounting and shareholder returns in 99 British companies in the years 1972-89. After correcting for heterogeneity biases inherent in the standard specifications of the problem, we find a strong positive relationship between CEO pay and within-company changes in shareholder returns, and no statistically significant relationship between CEO pay and within-company changes in accounting returns. Differences between firms in long-term average profitability do appear to have a substantial effect on CEO pay, while differences between firms in shareholder returns add nothing to the within-firm pay dynamics.These findings call into question the rationale for explicitly share-based incentive schemes
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CHEMKIN-III: A FORTRAN chemical kinetics package for the analysis of gas-phase chemical and plasma kinetics
This document is the user`s manual for the third-generation CHEMKIN package. CHEMKIN is a software package whose purpose is to facilitate the formation, solution, and interpretation of problems involving elementary gas-phase chemical kinetics. It provides a flexible and powerful tool for incorporating complex chemical kinetics into simulations of fluid dynamics. The package consists of two major software components: an Interpreter and a Gas-Phase Subroutine Library. The Interpreter is a program that reads a symbolic description of an elementary, user-specified chemical reaction mechanism. One output from the Interpreter is a data file that forms a link to the Gas-Phase Subroutine Library. This library is a collection of about 100 highly modular FORTRAN subroutines that may be called to return information on equations of state, thermodynamic properties, and chemical production rates. CHEMKIN-III includes capabilities for treating multi-fluid plasma systems, that are not in thermal equilibrium. These new capabilities allow researchers to describe chemistry systems that are characterized by more than one temperature, in which reactions may depend on temperatures associated with different species; i.e. reactions may be driven by collisions with electrons, ions, or charge-neutral species. These new features have been implemented in such a way as to require little or no changes to CHEMKIN implementation for systems in thermal equilibrium, where all species share the same gas temperature. CHEMKIN-III now has the capability to handle weakly ionized plasma chemistry, especially for application related to advanced semiconductor processing
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