6,503 research outputs found
The role of follow-on contracts in government-sponsored research and development
Role of follow-on contracts in government sponsored research and developmen
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Optimization of the neutron yield in fusion plasmas produced by Coulomb explosions of deuterium clusters irradiated by a petawatt laser
The kinetic energy of hot (multi-keV) ions from the laser-driven Coulomb explosion of deuterium clusters and the resulting fusion yield in plasmas formed from these exploding clusters has been investigated under a variety of conditions using the Texas Petawatt laser. An optimum laser intensity was found for producing neutrons in these cluster fusion plasmas with corresponding average ion energies of 14 keV. The substantial volume (1-10 mm(3)) of the laser-cluster interaction produced by the petawatt peak power laser pulse led to a fusion yield of 1.6x10(7) neutrons in a single shot with a 120 J, 170 fs laser pulse. Possible effects of prepulses are discussed. DOI: 10.1103/PhysRevE.87.023106Glenn Focht Memorial FellowshipNNSA DE-FC52-08NA28512DOE Office of Basic Energy SciencesPhysic
Analysis of Absorbing Times of Quantum Walks
Quantum walks are expected to provide useful algorithmic tools for quantum
computation. This paper introduces absorbing probability and time of quantum
walks and gives both numerical simulation results and theoretical analyses on
Hadamard walks on the line and symmetric walks on the hypercube from the
viewpoint of absorbing probability and time.Comment: LaTeX2e, 14 pages, 6 figures, 1 table, figures revised, references
added, to appear in Physical Review
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The Texas Petawatt Laser And Current Experiments
The Texas Petawatt Laser is operational with experimental campaigns executed in both F/40 and F3 target chambers. Recent improvements have resulted in intensities of >2x10(21) W/cm(2) on target. Experimental highlights include, accelerated electron energies of >2 GeV, DD fusion ion temperatures >25 keV and isochorically heated solids to 10-50 eV.Physic
A microfluidic chip based model for the study of full thickness human intestinal tissue using dual flow
© 2016 Author(s). The study of inflammatory bowel disease, including Ulcerative Colitis and Crohn's Disease, has relied largely upon the use of animal or cell culture models; neither of which can represent all aspects of the human pathophysiology. Presented herein is a dual flow microfluidic device which holds full thickness human intestinal tissue in a known orientation. The luminal and serosal sides are independently perfused ex vivo with nutrients with simultaneous waste removal for up to 72 h. The microfluidic device maintains the viability and integrity of the tissue as demonstrated through Haematoxylin & Eosin staining, immunohistochemistry and release of lactate dehydrogenase. In addition, the inflammatory state remains in the tissue after perfusion on the device as determined by measuring calprotectin levels. It is anticipated that this human model will be extremely useful for studying the biology and tes ting novel interventions in diseased tissue
Boundary Terms, Variational Principles and Higher Derivative Modified Gravity
We discuss the criteria that must be satisfied by a well-posed variational
principle. We clarify the role of Gibbons-Hawking-York type boundary terms in
the actions of higher derivative models of gravity, such as F(R) gravity, and
argue that the correct boundary terms are the naive ones obtained though the
correspondence with scalar-tensor theory, despite the fact that variations of
normal derivatives of the metric must be fixed on the boundary. We show in the
case of F(R) gravity that these boundary terms reproduce the correct ADM energy
in the hamiltonian formalism, and the correct entropy for black holes in the
semi-classical approximation.Comment: 54 pages, 2 figures. Several typos corrected, references added.
Version appearing in PR
An algorithm for counting circuits: application to real-world and random graphs
We introduce an algorithm which estimates the number of circuits in a graph
as a function of their length. This approach provides analytical results for
the typical entropy of circuits in sparse random graphs. When applied to
real-world networks, it allows to estimate exponentially large numbers of
circuits in polynomial time. We illustrate the method by studying a graph of
the Internet structure.Comment: 7 pages, 3 figures, minor corrections, accepted versio
Experimental study of fusion neutron and proton yields produced by petawatt-laser-irradiated D2-3He or CD4-3He clustering gases
We report on experiments in which the Texas Petawatt laser irradiated a
mixture of deuterium or deuterated methane clusters and helium-3 gas,
generating three types of nuclear fusion reactions: D(d, 3He)n, D(d, t)p and
3He(d, p)4He. We measured the yields of fusion neutrons and protons from these
reactions and found them to agree with yields based on a simple cylindrical
plasma model using known cross sections and measured plasma parameters. Within
our measurement errors, the fusion products were isotropically distributed.
Plasma temperatures, important for the cross sections, were determined by two
independent methods: (1) deuterium ion time-of-flight, and (2) utilizing the
ratio of neutron yield to proton yield from D(d, 3He)n and 3He(d, p)4He
reactions, respectively. This experiment produced the highest ion temperature
ever achieved with laser-irradiated deuterium clusters.Comment: 16 pages, 6 figure
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