11,119 research outputs found

    Experimental and theoretical investigation for the suppression of the plasma arc drop in the thermionic converter

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    Ion generation and recombination mechanisms in the cesium plasma as they pertain to the advanced mode thermionic energy converter were studied. The decay of highly ionized cesium plasma was studied in the near afterglow to examine the recombination processes. Very low recombination in such a plasma may prove to be of considerable importance in practical converters. The approaches of external cesium generation were vibrationally excited nitrogen as an energy source of ionization of cesium ion, and microwave power as a means of resonant sustenance of the cesium plasma. Experimental data obtained so far show that all three techniques - i.e., the non-LTE high-voltage pulsing, the energy transfer from vibrationally excited diatomic gases, and the external pumping with a microwave resonant cavity - can produce plasmas with their densities significantly higher than the Richardson density. The implication of these findings as related to Lam's theory is discussed

    Speed of light as measured by two terrestrial stable clocks

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    Despite the recent criticism within the special theory of relativity, there exists an arrangement of stable clocks rotating with the earth which predicts diurnal variations of the one-way speed of light, as suggested previously

    Predicting rare events in chemical reactions: application to skin cell proliferation

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    In a well-stirred system undergoing chemical reactions, fluctuations in the reaction propensities are approximately captured by the corresponding chemical Langevin equation. Within this context, we discuss in this work how the Kramers escape theory can be used to predict rare events in chemical reactions. As an example, we apply our approach to a recently proposed model on cell proliferation with relevance to skin cancer [P.B. Warren, Phys. Rev. E {\bf 80}, 030903 (2009)]. In particular, we provide an analytical explanation for the form of the exponential exponent observed in the onset rate of uncontrolled cell proliferation.Comment: New materials and references added. To appear in Physical Review

    Influence of retardation effects on 2D magnetoplasmon spectrum

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    Within dissipationless limit the magnetic field dependence of magnetoplasmon spectrum for unbounded 2DEG system found to intersect the cyclotron resonance line, and, then approaches the frequency given by light dispersion relation. Recent experiments done for macroscopic disc-shape 2DEG systems confirm theory expectations.Comment: 2 pages,2 figure

    Stellar Mass to Halo Mass Scaling Relation for X-ray Selected Low Mass Galaxy Clusters and Groups out to Redshift z1z\approx1

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    We present the stellar mass-halo mass scaling relation for 46 X-ray selected low-mass clusters or groups detected in the XMM-BCS survey with masses 2×1013MM5002.5×1014M2\times10^{13}M_{\odot}\lesssim M_{500}\lesssim2.5\times10^{14}M_{\odot} at redshift 0.1z1.020.1\le z \le1.02. The cluster binding masses M500M_{500} are inferred from the measured X-ray luminosities \Lx, while the stellar masses MM_{\star} of the galaxy populations are estimated using near-infrared imaging from the SSDF survey and optical imaging from the BCS survey. With the measured \Lx\ and stellar mass MM_{\star}, we determine the best fit stellar mass-halo mass relation, accounting for selection effects, measurement uncertainties and the intrinsic scatter in the scaling relation. The resulting mass trend is MM5000.69±0.15M_{\star}\propto M_{500}^{0.69\pm0.15}, the intrinsic (log-normal) scatter is σlnMM500=0.360.06+0.07\sigma_{\ln M_{\star}|M_{500}}=0.36^{+0.07}_{-0.06}, and there is no significant redshift trend M(1+z)0.04±0.47M_{\star}\propto (1+z)^{-0.04\pm0.47}, although the uncertainties are still large. We also examine MM_{\star} within a fixed projected radius of 0.50.5~Mpc, showing that it provides a cluster binding mass proxy with intrinsic scatter of 93%\approx93\% (1σ\sigma in M500M_{500}). We compare our M=M(M500,z)M_{\star}=M_{\star}(M_{500}, z) scaling relation from the XMM-BCS clusters with samples of massive, SZE-selected clusters (M5006×1014MM_{500}\approx6\times10^{14}M_{\odot}) and low mass NIR-selected clusters (M5001014MM_{500}\approx10^{14}M_{\odot}) at redshift 0.6z1.30.6\lesssim z \lesssim1.3. After correcting for the known mass measurement systematics in the compared samples, we find that the scaling relation is in good agreement with the high redshift samples, suggesting that for both groups and clusters the stellar content of the galaxy populations within R500R_{500} depends strongly on mass but only weakly on redshift out to z1z\approx1.Comment: 15 pages, 10 figures. Accepted for publication in MNRA

    Factorial Moments of Continuous Order

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    The normalized factorial moments FqF_q are continued to noninteger values of the order qq, satisfying the condition that the statistical fluctuations remain filtered out. That is, for Poisson distribution Fq=1F_q = 1 for all qq. The continuation procedure is designed with phenomenology and data analysis in mind. Examples are given to show how FqF_q can be obtained for positive and negative values of qq. With qq being continuous, multifractal analysis is made possible for multiplicity distributions that arise from self-similar dynamics. A step-by-step procedure of the method is summarized in the conclusion.Comment: 15 pages + 9 figures (figures available upon request), Late

    Probing neutrino mass hierarchies and ϕ13\phi_{13} with supernova neutrinos

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    We investigate the feasibility of probing the neutrino mass hierarchy and the mixing angle ϕ13\phi_{13} with the neutrino burst from a future supernova. An inverse power-law density ρrn\rho \sim r^{n} with varying nn is adopted in the analysis as the density profile of a typical core-collapse supernova. The survival probabilities of νe\nu_{e} and νˉe\bar{\nu}_{e} are shown to reduce to two-dimensional functions of nn and ϕ13\phi_{13}. It is found that in the nsin2ϕ13n-\sin^{2} \phi_{13} parameter space, the 3D plots of the probability functions exhibit highly non-trivial structures that are sensitive to the mass hierarchy, the mixing angle ϕ13\phi_{13}, and the value of nn. The conditions that lead to observable differences in the 3D plots are established. With the uncertainty of nn considered, a qualitative analysis of the Earth matter effect is also included.Comment: 16 pages, 3 figures. Ref [11] added, and some typos correcte

    Preliminary results from a simulation of quenched QCD with overlap fermions on a large lattice

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    We simulate quenched QCD with the overlap Dirac operator. We work with the Wilson gauge action at beta=6 on an 18^3x64 lattice. We calculate quark propagators for a single source point and quark mass ranging from am_q=0.03 to 0.75. We present here preliminary results based on the propagators for 60 gauge field configurations.Comment: Lattice2003(chiral); 9 latex pages (espcrc2.sty), 13 figures. Based on talks given by C.H., L.L. and C.R. at 21st International Symposium on Lattice Field Theory (Lattice 2003), Tsubuka, Japan, 15-19 July 2003. Repitition in references corrected and one reference adde
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