3,148 research outputs found
The Opera Instrument: An Advanced Curation Development for Mars Sample Return Organic Contamination Monitoring
Mars Sample Return (MSR) requires strict organic contamination control (CC) and contamination knowledge (CK) as outlined by the Mars 2020 Organic Contamination Panel (OCP). This includes a need to monitor surficial organic contamination to a ng/sq. cm sensitivity level. Archiving and maintaining this degree of surface cleanliness may be difficult but has been achieved. MSR's CK effort will be very important because all returned samples will be studied thoroughly and in minute detail. Consequently, accurate CK must be collected and characterized to best interpret scientific results from the returned samples. The CK data are not only required to make accurate measurements and interpretations for carbon-depleted martian samples, but also to strengthen the validity of science investigations performed on the samples. The Opera instrument prototype is intended to fulfill a CC/CK role in the assembly, cleaning, and overall contamination history of hardware used in the MSR effort, from initial hardware assembly through post-flight sample curation. Opera is intended to monitor particulate and organic contamination using quartz crystal microbalances (QCMs), in a self-contained portable package that is cleanroom-compliant. The Opera prototype is in initial development capable of approximately 100 ng/sq. cm organic contamination sensitivity, with additional development planned to achieve 1 ng/sq. cm. The Opera prototype was funded by the 2017 NASA Johnson Space Center Innovation Charge Account (ICA), which provides funding for small, short-term projects
Applicability and Utility of the Astromaterials X-Ray Computed Tomography Laboratory at Johnson Space Center
The Astromaterials Acquisition and Curation Office at NASAs Johnson Space Center is responsible for curating all of NASAs astromaterial sample collections (i.e. Apollo samples, Luna Samples, Antarctic Meteorites, Cosmic Dust Particles, Microparticle Impact Collection, Genesis solar wind atoms, Stardust comet Wild-2 particles, Stardust interstellar particles, and Hayabusa asteroid Itokawa particles) [1-3]. To assist in sample curation and distribution, JSC Curation has recently installed an X-ray computed tomography (XCT) scanner to visualize and characterize samples in 3D. [3] describes the instrumental set-up and the utility of XCT to astromaterials curation. Here we describe some of the current and future projects and illustrate the usefulness of XCT in studying astromaterials
Withholding and withdrawing therapy at the intensive care units of the University Hospital of Innsbruck, Austria
Heavy-Quark Diffusion and Hadronization in Quark-Gluon Plasma
We calculate diffusion and hadronization of heavy quarks in high-energy
heavy-ion collisions implementing the notion of a strongly coupled quark-gluon
plasma in both micro- and macroscopic components. The diffusion process is
simulated using relativistic Fokker-Planck dynamics for elastic scattering in a
hydrodynamic background. The heavy-quark transport coefficients in the medium
are obtained from non-perturbative -matrix interactions which build up
resonant correlations close to the transition temperature. The latter also form
the basis for hadronization of heavy quarks into heavy-flavor mesons via
recombination with light quarks from the medium. The pertinent resonance
recombination satisfies energy conservation and provides an equilibrium mapping
between quark and meson distributions. The recombination probability is derived
from the resonant heavy-quark scattering rate. Consequently, recombination
dominates at low transverse momentum () and yields to fragmentation at
high . Our approach thus emphasizes the role of resonance correlations in
the diffusion and hadronization processes. We calculate the nuclear
modification factor and elliptic flow of - and -mesons for Au-Au
collisions at the Relativistic Heavy Ion Collider, and compare their
decay-electron spectra to available data. We also find that a realistic
description of the medium flow is essential for a quantitative interpretation
of the data.Comment: 16 pages, 14 figure
The effect of the combined administration of colloids and Ringer's Lactate on the coagulation system - an in vitro study using thrombelastography (roTEGÂź)
Recombination Models
We review the current status of recombination and coalescence models that
have been successfully applied to describe hadronization in heavy ion
collisions at RHIC energies. Basic concepts as well as actual implementations
of the idea are discussed. We try to evaluate where we stand in our
understanding at the moment and what remains to be done in the future.Comment: Plenary Talk at Quark Matter 2004, submitted to J. Phys. G, 8 pages,
3 figure
High Energy Nuclear Collisions: Theory Overview
We review some basic concepts of Relativistic Heavy Ion Physics and discuss
our understanding of some key results from the experimental program at the
Relativistic Heavy Ion Collider (RHIC). We focus in particular on the early
time dynamics of nuclear collisions, some result from lattice QCD, hard probes
and photons.Comment: 11 pages, 3 figures; delivered at ISNP 2009, published in Praman
Particle correlations at RHIC from parton coalescence dynamics -- first results
A new dynamical approach that combines covariant parton transport theory with
hadronization channels via parton coalescence and fragmentation is applied to
Au+Au at RHIC. Basic consequences of the simple coalescence formulas, such as
elliptic flow scaling and enhanced proton/pion ratio, turn out to be rather
sensitive to the spacetime aspects of coalescence dynamics.Comment: Contribution to Quark Matter 2004 (January 11-17, 2004, Oakland, CA).
4 pages, 2 EPS figs, IOP style fil
The Evidence for a Pentaquark Signal and Kinematic Reflections
Several recent experiments have reported evidence for a narrow baryon
resonance with positive strangeness () at a mass of 1.54 GeV/.
Baryons with cannot be conventional states and the reports have
thus generated much theoretical speculation about the nature of possible
baryons, including a 5-quark, or pentaquark, interpretation. We show that
narrow enhancements in the effective mass spectrum can be generated as
kinematic reflections resulting from the decay of mesons, such as the
, the and the .Comment: 4 pages, 4 figure
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