2,186 research outputs found
The Systematic Interpretation of Cosmic Ray Data (The Transport Project)
The Transport project's primary goals were to: (1) Provide measurements of critical fragmentation cross sections; (2) Study the cross section systematics; (3) Improve the galactic cosmic ray propagation methodology; and (4) Use the new cross section measurements to improve the interpretation of cosmic ray data. To accomplish these goals a collaboration was formed consisting of researchers in the US at Louisiana State University (LSU), Lawrence Berkeley Laboratory (LBL), Goddard Space Flight Center (GSFC), the University of Minnesota (UM), New Mexico State University (NMSU), in France at the Centre d'Etudes de Saclay and in Italy at the Universita di Catania. The US institutions, lead by LSU, were responsible for measuring new cross sections using the LBL HISS facility, analysis of these measurements and their application to interpreting cosmic ray data. France developed a liquid hydrogen target that was used in the HISS experiment and participated in the data interpretation. Italy developed a Multifunctional Neutron Spectrometer (MUFFINS) for the HISS runs to measure the energy spectra, angular distributions and multiplicities of neutrons emitted during the high energy interactions. The Transport Project was originally proposed to NASA during Summer, 1988 and funding began January, 1989. Transport was renewed twice (1991, 1994) and finally concluded at LSU on September, 30, 1997. During the more than 8 years of effort we had two major experiment runs at LBL, obtained data on the interaction of twenty different beams with a liquid hydrogen target, completed the analysis of fifteen of these datasets obtaining 590 new cross section measurements, published nine journal articles as well as eighteen conference proceedings papers, and presented more than thirty conference talks
A Stellar Model-fitting Pipeline for Solar-like Oscillations
Over the past two decades, helioseismology has revolutionized our
understanding of the interior structure and dynamics of the Sun.
Asteroseismology will soon place this knowledge into a broader context by
providing structural data for hundreds of Sun-like stars. Solar-like
oscillations have already been detected from the ground in several stars, and
NASA's Kepler mission is poised to unleash a flood of stellar pulsation data.
Deriving reliable asteroseismic information from these observations demands a
significant improvement in our analysis methods. We report the initial results
of our efforts to develop an objective stellar model-fitting pipeline for
asteroseismic data. The cornerstone of our automated approach is an
optimization method using a parallel genetic algorithm. We describe the details
of the pipeline and we present the initial application to Sun-as-a-star data,
yielding an optimal model that accurately reproduces the known solar
properties.Comment: 5 pages, 2 figs, Stellar Pulsation: Challenges for Theory and
Observation (proceedings to be published by AIP
Quantum Process Estimation via Generic Two-Body Correlations
Performance of quantum process estimation is naturally limited to
fundamental, random, and systematic imperfections in preparations and
measurements. These imperfections may lead to considerable errors in the
process reconstruction due to the fact that standard data analysis techniques
presume ideal devices. Here, by utilizing generic auxiliary quantum or
classical correlations, we provide a framework for estimation of quantum
dynamics via a single measurement apparatus. By construction, this approach can
be applied to quantum tomography schemes with calibrated faulty state
generators and analyzers. Specifically, we present a generalization of "Direct
Characterization of Quantum Dynamics" [M. Mohseni and D. A. Lidar, Phys. Rev.
Lett. 97, 170501 (2006)] with an imperfect Bell-state analyzer. We demonstrate
that, for several physically relevant noisy preparations and measurements, only
classical correlations and small data processing overhead are sufficient to
accomplish the full system identification. Furthermore, we provide the optimal
input states for which the error amplification due to inversion on the
measurement data is minimal.Comment: 7 pages, 2 figure
Design and Development of CubeSat Solar Array Deployment Mechanisms Using Shape Memory Alloys
The Advanced eLectrical Bus (ALBus) project is a technology demonstration mission of a 3-U CubeSat with an advanced, digitally controlled electrical power system capability and the novel use of Shape Memory Alloy (SMA) technology for reliable solar array deployable mechanisms. The ALBus cubesat has a need to deploy four solar arrays in addition to the body-mounted arrays on each side of the cubesat. A goal of the mission is to utilize the SMAs being developed at the NASA Glenn Research Center to deploy these solar arrays. The use of SMAs allows for the ability to test and reset the flight deployment mechanism prior to flight which reduces the risk of on orbit deployment failures common on cubesats. As a result, an SMA driven Retention and Release mechanism and an SMA driven hinge was designed, developed, and being prepared for flight. This paper summarized the development of these mechanisms, types and functionalities of SMAs used, and lessons learned throughout the process
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Direct Estimation of Single- and Two-Qubit Hamiltonians and Relaxation Rates
We provide an approach for characterization of quantum Hamiltonian systems via utilizing a single measurement device. Specifically, we demonstrate how external quantum correlations can be used for Hamiltonian identification tasks. We explicitly introduce experimental procedures for direct estimation of single- and two-qubit Hamiltonian parameters, and also for simultaneous estimation of transverse and longitudinal relaxation rates, using a single Bell-state analyzer. An advantage of our method over the earlier approaches is that it has a built-in feature which makes it suitable for partial characterization of Hamiltonian parameters.Chemistry and Chemical Biolog
Vaccinia virus-regulated acute phase cytokine production in human fibroblasts, U937 cells and endothelium.
The production of acute phase cytokines, interleukin 6 (IL-6), tumour necrosis factor (TNFalpha) and interleukin 1 (IL-1beta), was studied in primary cultures of human skin fibroblasts, human monocytic cell line U937 and primary cultures of human umbilical vein endothelial cells (HUVEC) after in vitro infection with vaccinia virus. Significant increase in IL-6 mRNA followed by enhanced protein secretion into the culture media was found in fibroblasts, U937 cells, and HUVEC. TNFalpha increased production in vaccinia virus infected U937 cells resembled closely the pattern of IL-6 production observed in the infected cells. Transient increase in NF-kappaB binding activity was found in the infected U937 (at 90 min) and endothelial (at 30 min) cells. Vaccinia virus induced cytokine production appeared to be transcriptional
TETRA Observation of Gamma Rays at Ground Level Associated with Nearby Thunderstorms
Terrestrial Gamma ray Flashes (TGFs) -- very short, intense bursts of
electrons, positrons, and energetic photons originating from terrestrial
thunderstorms -- have been detected with satellite instruments. TETRA, an array
of NaI(Tl) scintillators at Louisiana State University, has now been used to
detect similar bursts of 50 keV to over 2 MeV gamma rays at ground level. After
2.6 years of observation, twenty-four events with durations 0.02- 4.2 msec have
been detected associated with nearby lightning, three of them coincident events
observed by detectors separated by ~1000 m. Nine of the events occurred within
6 msec and 3 miles of negative polarity cloud-to-ground lightning strokes with
measured currents in excess of 20 kA. The events reported here constitute the
first catalog of TGFs observed at ground level in close proximity to the
acceleration site.Comment: To be published in Journal of Geophysical Research: Space Phys. 118,
Implications of new measurements of O-16 + p + C-12,13, N-14,15 for the abundances of C, N isotopes at the cosmic ray source
The fragmentation of a 225 MeV/n O-16 beam was investigated at the Bevalac. Preliminary cross sections for mass = 13, 14, 15 fragments are used to constrain the nuclear excitation functions employed in galactic propagation calculations. Comparison to cosmic ray isotonic data at low energies shows that in the cosmic ray source C-13/C approximately 2% and N-14/0=3-6%. No source abundance of N-15 is required with the current experimental results
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