1,801 research outputs found

    Fast trajectory matching using small binary images

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    This paper proposes a new trajectory matching method using logic operations on binary images. By using small binary images we are able to effectively utilize the large word size offered in modern CPU architectures, resulting in a very efficient evaluation of similarities between trajectories. The efficiency is caused by the fact that all bits in the same word are processed in parallel. Representing trajectories as small binary images has other advantages, such as a low space requirement and good noise resistance. The proposed method is evaluated on a publicly available dataset, and is compared to the more sophisticated Longest Common Subsequence (LCSS) method. In addition, synthetic experiments show the good efficiency and accuracy of the proposed method, enabling real time trajectory retrieval on databases with millions of trajectories.postprin

    Non-Thermal X-ray Properties of Rotation Powered Pulsars and Their Wind Nebulae

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    We present a statistical study of the non-thermal X-ray emission of 27 young rotation powered pulsars (RPPs) and 24 pulsar wind nebulae (PWNe) by using the Chandra and the XMM-Newton observations, which with the high spatial resolutions enable us to spatially resolve pulsars from their surrounding PWNe. We obtain the X-ray luminosities and spectra separately for RPPs and PWNe, and then investigate their distribution and relation to each other as well as the relation with the pulsar rotational parameters. In the pair-correlation analysis we find that: (1) the X-ray (2-10 keV) luminosities of both pulsar and PWN (L_{psr} and L_{pwn}) display a strong correlation with pulsar spin down power Edot and characteristic age, and the scalings resulting from a simple linear fit to the data are L_{psr} \propto Edot^{0.92 \pm 0.04} and L_{pwn} \propto Edot^{1.45 \pm 0.08} (68% confidence level), respectively, however, both the fits are not statistically acceptable; (2) L_{psr} also shows a possible weak correlation with pulsar period P and period derivative Pdot, whereas L_{pwn} manifests a similar weak correlation with Pdot only; (3) The PWN photon index Gamma_{pwn} is positively correlated with L_{pwn} and L_{pwn}/Edot. We also found that the PWN X-ray luminosity is typically 1 to 10 times larger than that from the underlying pulsar, and the PWN photon indices span a range of ~1.5 to ~2. The statistic study of PWN spectral properties supports the particle wind model in which the X-ray emitting electrons are accelerated by the termination shock of the wind.Comment: 15 pages, 9 figures, 3 Tables, ApJ accepted version. Substantial revision, especially luminosity uncertainty taken into accounted and one fig added. Main conclusions unchange

    Magnetic Nanoparticle-Based Hyperthermia for Head & Neck Cancer in Mouse Models

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    In this study, magnetic iron oxide nanoparticle induced hyperthermia is applied for treatment of head and neck cancer using a mouse xenograft model of human head and neck cancer (Tu212 cell line). A hyperthermia system for heating iron oxide nanoparticles was developed by using alternating magnetic fields. Both theoretical simulation and experimental studies were performed to verify the thermotherapy effect. Experimental results showed that the temperature of the tumor center has dramatically elevated from around the room temperature to about 40oC within the first 5-10 minutes. Pathological studies demonstrate epithelial tumor cell destruction associated with the hyperthermia treatment

    901-25 The Paradox of Donor Stimulation of Endothelial-induced Smooth Muscle Growth

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    Cardiac allograft vasculopathy (CAV) is the major cause of long-term morbidity and mortality in cardiac transplant recipients. It appears to be related to immune damage to the coronary endothelial cells, resulting in intimal proliferation. In order to delineate the mechanisms by which CAY can occur, a co-culture model of human endothelial cells (EC) and smooth muscle cells (SMC) obtained from the donor at the time of organ procurement was utilized. These cells were separated by collagenase digestion, and cultured for four passages. EC and SMC were then grown to confluence in the separate chambers of a co-culture plate separated by a 0.45 micron Millipore filter. Preserved lymphocytes (LYMPH) obtained from the donor and pooled blood lymphocytes from the recipient 3-4 weeks following transplant were added to the EC well so as to cause an immunologic stimulation of the EC. None of the recipients were exposed to monoclonal or polyclonal antibodies to lymphocytes. All cultures and assays were done in triplicate. Results are as follows:Patient#% Increase in donor lymph H3thymidinep ValueDonor 1+510.04Donor 2+450.05Donor 3+1040.05Donor 4+250.01Donor 5-19NSThe donor EC/donor LYMPH co-culture stimulated SMC growth measured by H3thymidine incorporation in 4 of 5 patients. The donor EC/recipient LYMPH co-culture did not result in significant SMC H3thymidine incorporation.ConclusionThese paradoxical findings of a lack in significant SMC proliferation in the recipient stimulated donor cells continue to raise questions in relation to the effects of circulating lymphocytes on the development of cardiac allograft vasculopathy

    Effective suppression of parametric instabilities with decoupled broadband lasers in plasma

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    A theoretical analysis for the stimulated Raman scattering (SRS) instability driven by two laser beams with certain frequency difference is presented. It is found that strong coupling and enhanced SRS take place only when the unstable regions for each beam are overlapped in the wavenumber space. Hence a threshold of the beam frequency difference for their decoupling is found as a function of their intensity and plasma density. Based upon this, a strategy to suppress the SRS instability with decoupled broadband lasers (DBLs) is proposed. A DBL can be composed of tens or even hundreds of beamlets, where the beamlets are distributed uniformly in a broad spectrum range such as over 10% of the central frequency. Decoupling among the beamlets is found due to the limited beamlet energy and suitable frequency difference between neighboring beamlets. Particle-in-cell simulations demonstrate that SRS can be almost completely suppressed with DBLs under the laser intensity ∌ 1015 W/cm2. Moreover, stimulated Brillouin scattering (SBS) will be suppressed simultaneously with DBLs can be attractive for driving inertial confined fusion

    Scaling of the Equilibrium Magnetization in the Mixed State of Type-II Superconductors

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    We discuss the analysis of mixed-state magnetization data of type-II superconductors using a recently developed scaling procedure. It is based on the fact that, if the Ginzburg-Landau parameter kappa does not depend on temperature, the magnetic susceptibility is a universal function of H/H_c2(T), leading to a simple relation between magnetizations at different temperatures. Although this scaling procedure does not provide absolute values of the upper critical fieldH_c2(T), its temperature variation can be established rather accurately. This provides an opportunity to validate theoretical models that are usually employed for the evaluation of H_c2(T) from equilibrium magnetization data. In the second part of the paper we apply this scaling procedure for a discussion of the notorious first order phase transition in the mixed state of high temperature superconductors. Our analysis, based on experimental magnetization data available in the literature, shows that the shift of the magnetization accross the transition may adopt either sign, depending on the particular chosen sample. We argue that this observation is inconsistent with the interpretation that this transition always represents the melting transition of the vortex lattice.Comment: 18 pages, 12 figure

    Unusual competition of superconductivity and charge-density-wave state in a compressed topological kagome metal

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    Understanding the competition between superconductivity and other ordered states (such as antiferromagnetic or charge-density-wave (CDW) state) is a central issue in condensed matter physics. The recently discovered layered kagome metal AV3Sb5 (A = K, Rb, and Cs) provides us a new playground to study the interplay of superconductivity and CDW state by involving nontrivial topology of band structures. Here, we conduct high-pressure electrical transport and magnetic susceptibility measurements to study CsV3Sb5 with the highest Tc of 2.7 K in AV3Sb5 family. While the CDW transition is monotonically suppressed by pressure, superconductivity is enhanced with increasing pressure up to P1~0.7 GPa, then an unexpected suppression on superconductivity happens until pressure around 1.1 GPa, after that, Tc is enhanced with increasing pressure again. The CDW is completely suppressed at a critical pressure P2~2 GPa together with a maximum Tc of about 8 K. In contrast to a common dome-like behavior, the pressure-dependent Tc shows an unexpected double-peak behavior. The unusual suppression of Tc at P1 is concomitant with the rapidly damping of quantum oscillations, sudden enhancement of the residual resistivity and rapid decrease of magnetoresistance. Our discoveries indicate an unusual competition between superconductivity and CDW state in pressurized kagome lattice.Comment: 16 pages, 4 figure

    Series expansions of the percolation probability for directed square and honeycomb lattices

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    We have derived long series expansions of the percolation probability for site and bond percolation on directed square and honeycomb lattices. For the square bond problem we have extended the series from 41 terms to 54, for the square site problem from 16 terms to 37, and for the honeycomb bond problem from 13 terms to 36. Analysis of the series clearly shows that the critical exponent ÎČ\beta is the same for all the problems confirming expectations of universality. For the critical probability and exponent we find in the square bond case, qc=0.3552994±0.0000010q_c = 0.3552994\pm 0.0000010, ÎČ=0.27643±0.00010\beta = 0.27643\pm 0.00010, in the square site case qc=0.294515±0.000005q_c = 0.294515 \pm 0.000005, ÎČ=0.2763±0.0003\beta = 0.2763 \pm 0.0003, and in the honeycomb bond case qc=0.177143±0.000002q_c = 0.177143 \pm 0.000002, ÎČ=0.2763±0.0002\beta = 0.2763 \pm 0.0002. In addition we have obtained accurate estimates for the critical amplitudes. In all cases we find that the leading correction to scaling term is analytic, i.e., the confluent exponent Δ=1\Delta = 1.Comment: LaTex with epsf, 26 pages, 2 figures and 2 tables in Postscript format included (uufiled). LaTeX version of tables also included for the benefit of those without access to PS printers (note that the tables should be printed in landscape mode). Accepted by J. Phys.

    Mean-Field Analysis and Monte Carlo Study of an Interacting Two-Species Catalytic Surface Reaction Model

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    We study the phase diagram and critical behavior of an interacting one dimensional two species monomer-monomer catalytic surface reaction model with a reactive phase as well as two equivalent adsorbing phase where one of the species saturates the system. A mean field analysis including correlations up to triplets of sites fails to reproduce the phase diagram found by Monte Carlo simulations. The three phases coexist at a bicritical point whose critical behavior is described by the even branching annihilating random walk universality class. This work confirms the hypothesis that the conservation modulo 2 of the domain walls under the dynamics at the bicritical point is the essential feature in producing critical behavior different from directed percolation. The interfacial fluctuations show the same universal behavior seen at the bicritical point in a three-species model, supporting the conjecture that these fluctuations are a new universal characteristic of the model.Comment: 11 pages using RevTeX, plus 4 Postscript figures. Uses psfig.st
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