37,845 research outputs found
Computer aided processing using laser measurements
The challenge exists of processing the STS and its cargo through KSC facilities in the most timely and cost effective manner possible. To do this a 3-D computer graphics data base was established into which was entered the STS, payloads, and KSC facilities. The facility drawing data are enhanced by laser theodolite measurements into an as-built configuration. Elements of the data base were combined to study orbiter/facility interfaces payload/facility access problems and design/arrangement of various GSE to support processing requirements. With timely analysis/design utilizing the 3-D computer graphics system, costly delays can be avoided. Better methodology can be analyzed to determine procedures for cost avoidance
Cyclosporin A inhibits PGE2 release from vascular smooth muscle cells
The influence of the fungoid undecapeptide cyclosporin A (CyA) on PGE2 release from cultured rat aortic smooth muscle cells was investigated in this study. We found that CyA time and concentration dependently (ED50:500 ng/ml) inhibited PGE2 release from the cells. CyA attenuated both basal and PGE2 release evoked by angiotensin II (10(-10)-10(-6) M), arginine vasopressin (10(-10)-10(-6) M) and ionomycin (10(-9)-10(-6) M). CyA (1 microgram/ml) did not affect the conversion of exogenous arachidonic acid (1 microM) into PGE2. The inhibitory effect of CyA was neutralized by high concentrations of the calcium ionophore ionomycin (greater than 3 X 10(-6) M). Taken together our results indicate that CyA inhibits both basal and vasoconstrictor evoked PGE2 release from vascular smooth muscle by impairing the availability of free arachidonic acid rather than by inhibiting the conversion of arachidonic acid into PGE2
Baryon number and strangeness: signals of a deconfined antecedent
The correlation between baryon number and strangeness is used to discern the
nature of the deconfined matter produced at vanishing chemical potential in
high-energy nuclear collisions at the BNL RHIC. Comparisons of results of
various phenomenological models with correlations extracted from lattice QCD
calculations suggest that a quasi-particle picture applies. At finite baryon
densities, such as those encountered at the CERN SPS, it is demonstrated that
the presence of a first-order phase transition and the accompanying development
of spinodal decomposition would significantly enhance the number of strangeness
carriers and the associated fluctuations.Comment: 10 pages, 4 figures, latex, to appear in the proceedings of the
Workshop on Correlations and Fluctuations in Relativistic Nuclear collisions,
(MIT, April 21-23,2005
A diode device combining lateral field-effect transport and vertical tunneling in a multi-quantum-well heterostructure
The authors discuss an electronic device with asymmetric contacts to a InGaAs-InP multilayer heterostructure. Current enters via an alloyed ohmic contact into the quantum wells (QWs) and flows laterally along capacitively coupled channels. It leaves via tunneling between the layers and through a forward-biased surface Schottky contact. A step-like I-V dependence is observed and interpreted by a model calculation
The GEMPAK Barnes objective analysis scheme
GEMPAK, an interactive computer software system developed for the purpose of assimilating, analyzing, and displaying various conventional and satellite meteorological data types is discussed. The objective map analysis scheme possesses certain characteristics that allowed it to be adapted to meet the analysis needs GEMPAK. Those characteristics and the specific adaptation of the scheme to GEMPAK are described. A step-by-step guide for using the GEMPAK Barnes scheme on an interactive computer (in real time) to analyze various types of meteorological datasets is also presented
Searching for the QCD Critical Point Using Particle Ratio Fluctuations and Higher Moments of Multiplicity Distributions
Dynamical fluctuations in global conserved quantities such as baryon number,
strangeness, or charge may be observed near a QCD critical point. Results from
new measurements of dynamical , , and ratio fluctuations
are presented. The commencing of a QCD critical point search at RHIC has
extended the reach of possible measurements of dynamical , , and
ratio fluctuations from Au+Au collisions to lower energies. The STAR
experiment has performed a comprehensive study of the energy dependence of
these dynamical fluctuations in Au+Au collisions at the energies
= 7.7, 11.5, 39, 62.4, and 200 GeV. New results are compared to
previous measurements and to theoretical predictions from several models. The
measured dynamical fluctuations are found to be independent of
collision energy, while dynamical and fluctuations have a
negative value that increases toward zero at top RHIC energy. Fluctuations of
the higher moments of conserved quantities (net-proton and net-charge)
distributions, which are predicted to be sensitive to the presence of a
critical point, are also presented.Comment: 4 pages, 2 figures, Proceedings of the 21st International Conference
On Ultra-Relativistic Nucleus-Nucleus Collisions (Quark Matter 2011), Annecy,
France, May 23 - May 28, 201
Current Induced Excitations in Cu/Co/Cu Single Ferromagnetic Layer Nanopillars
Current-induced magnetic excitations in Cu/Co/Cu single layer nanopillars
(~50 nm in diameter) have been studied experimentally as a function of Co layer
thickness at low temperatures for large applied fields perpendicular to the
layers. For asymmetric junctions current induced excitations are observed at
high current densities for only one polarity of the current and are absent at
the same current densities in symmetric junctions. These observations confirm
recent predictions of spin-transfer torque induced spin wave excitations in
single layer junctions with a strong asymmetry in the spin accumulation in the
leads.Comment: 4 pages, 3 figures, submitted to Phys. Rev. Let
Resonance Production on Nuclei at High Energies: Nuclear-Medium Effects and Space-Time Picture
The influence of nuclear matter on the properties of coherently produced
resonances is discussed. It is shown that, in general, the mass distribution of
resonance decay products has a two-component structure corresponding to decay
outside and inside the nucleus. The first (narrow) component of the amplitude
has a Breit-Wigner form determined by the vacuum values of mass and width of
the resonance. The second (broad) component corresponds to interactions of the
resonance with the nuclear medium. It can be also described by a Breit-Wigner
shape with parameters depending e.g. on the nuclear density and on the cross
section of the resonance-nucleon interaction. The resonance production is
examined both at intermediate energies, where interactions with the nucleus can
be considered as a series of successive local rescatterings, and at high
energies, , where a change of interaction picture occurs. This
change of mechanisms of the interactions with the nucleus is typical for the
description within the Regge theory approach and is connected with the nonlocal
nature of the reggeon interaction.Comment: 22 pages LaTeX, 1 Postscript file containing 7 figures; addition in
beginning of Ch. 2; Nucl. Phys. A, to be publishe
The Mechanics of Malaria Parasite Invasion of the Human Erythrocyte - Towards a Reassessment of the Host Cell Contribution
Despite decades of research, we still know little about the mechanics of Plasmodium host cell invasion. Fundamentally, while the essential or nonâessential nature of different parasite proteins is becoming clearer, their actual function and how each comes together to govern invasion are poorly understood. Furthermore, in recent years an emerging world view is shifting focus away from the parasite actinâmyosin motor being the sole force responsible for entry to an appreciation of host cell dynamics and forces and their contribution to the process. In this review, we discuss merozoite invasion of the erythrocyte, focusing on the complex set of preâinvasion events and how these might prime the red cell to facilitate invasion. While traditionally parasite interactions at this stage have been viewed simplistically as mediating adhesion only, recent work makes it apparent that by interacting with a number of host receptors and signalling pathways, combined with secretion of parasiteâderived lipid material, that the merozoite may initiate cytoskeletal reâarrangements and biophysical changes in the erythrocyte that greatly reduce energy barriers for entry. Seen in this light Plasmodium invasion may well turn out to be a balance between host and parasite forces, much like that of other pathogen infection mechanisms
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