3,281 research outputs found

    Model driven testing based on test history

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    We consider software systems consisting of a set of components running as a sequential process. We model such software systems as a special class of transition systems. The difference with existing approaches is that we propose a test procedure based on the structure of the model and the prior test history that can be used for exhaustive testing in an efficient way. On top of that we provide a statistical stopping rule, that is independent of the underlying way of walking through the system, which allows us to stop earlier with a certain statistical reliability.</p

    Ratios of BB and DD Meson Decay Constants in Relativistic Quark Model

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    We calculate the ratios of BB and DD meson decay constants by applying the variational method to the relativistic hamiltonian of the heavy meson. We adopt the Gaussian and hydrogen-type trial wave functions, and use six different potentials of the potential model. We obtain reliable results for the ratios, which are similar for different trial wave functions and different potentials. The obtained ratios show the deviation from the nonrelativistic scaling law, and they are in a pretty good agreement with the results of the Lattice calculations.Comment: 13 pages, 1 Postscript figur

    The policy iteration method for the optimal stopping of a markov chain with an application

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    Impact of Individual Acute Phase Serum Amyloid A Isoforms on HDL Metabolism in Mice

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    The acute phase (AP) reactant serum amyloid A (SAA), an HDL apolipoprotein, exhibits pro-inflammatory activities, but its physiological function(s) are poorly understood. Functional differences between SAA1.1 and SAA2.1, the two major SAA isoforms, are unclear. Mice deficient in either isoform were used to investigate plasma isoform effects on HDL structure, composition, and apolipoprotein catabolism. Lack of either isoform did not affect the size of HDL, normally enlarged in the AP, and did not significantly change HDL composition. Plasma clearance rates of HDL apolipoproteins were determined using native HDL particles. The fractional clearance rates (FCRs) of apoA-I, apoA-II, and SAA were distinct, indicating that HDL is not cleared as intact particles. The FCRs of SAA1.1 and SAA2.1 in AP mice were similar, suggesting that the selective deposition of SAA1.1 in amyloid plaques is not associated with a difference in the rates of plasma clearance of the isoforms. Although the clearance rate of SAA was reduced in the absence of the HDL receptor, scavenger receptor class B type I (SR-BI), it remained significantly faster compared with that of apoA-I and apoA-II, indicating a relatively minor role of SR-BI in SAA’s rapid clearance. These studies enhance our understanding of SAA metabolism and SAA’s effects on AP-HDL composition and catabolism

    Raman Scattered He II λ\lambda 6545 Line in the Symbiotic Star V1016 Cygni

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    We present a spectrum of the symbiotic star V1016 Cyg observed with the 3.6 m Canada-France-Hawaii Telescope, in order to illustrate a method to measure the covering factor of the neutral scattering region around the giant component with respect to the hot emission region around the white dwarf component. In the spectrum, we find broad wings around Hα\alpha and a broad emission feature around 6545A˚{\rm \AA} that is blended with the [N II]λ \lambda 6548 line. These two features are proposed to be formed by Raman scattering by atomic hydrogen, where the incident radiation is proposed to be UV continuum radiation around LyÎČ\beta in the former case and He II λ\lambda 1025 emission line arising from n=6→n=2n=6\to n=2 transitions for the latter feature. We remove the Hα\alpha wings by a template Raman scattering wing profile and subtract the [N II] λ\lambda 6548 line using the 3 times stronger [N II] λ\lambda 6583 feature in order to isolate the He II Raman scattered 6545 \AA line. We obtain the flux ratio F6545/F6560=0.24F_{6545}/F_{6560}=0.24 of the He II λ\lambda 6560 emission line and the 6545 \AA feature for V1016 Cyg. Under the assumption that the He II emission from this object is isotropic, this ratio is converted to the ratio Ί6545/Ί1025=0.17\Phi_{6545}/\Phi_{1025}=0.17 of the number of the incident photons and that of the scattered photons. This implies that the scattering region with H I column density NHI≄1020cm−2N_{HI}\ge 10^{20}{\rm cm^{-2}} covers 17 per cent of the emission region. By combining the presumed binary period ∌100\sim 100 yrs of this system we infer that a significant fraction of the slow stellar wind from the Mira component is ionized and that the scattering region around the Mira extends a few tens of AU, which is closely associated with the mass loss process of the Mira component.Comment: 12 pages, 6 figures, accepted for publication in Ap

    Histamine as a marker for hydroxyl radicals

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    During inflammation an influx of neutrophils and release of mediators from mast cells (such as histamine) take place. The stimulated neutrophils can produce reactive oxygen species (ROS). One of these ROS is the highly reactive hydroxyl radical (OH.). It would be interesting to be able to quantify the extent of ROS formation. We investigated if histamine which is present at the inflammation site can serve as an endogenous marker for the formation of OH.. We found that histamine after incubation with OH. gave two distinct products in our HPLC system. One of the products gave the same characteristics as the synthesized 2-imidazolone derivative of histamine. This suggests that this derivative will be formed when histamine is incubated with OH.

    Magnetic Field Dependence of Macroscopic Quantum Tunneling and Coherence of Ferromagnetic Particle

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    We calculate the quantum tunneling rate of a ferromagnetic particle of ∌100A˚\sim 100 \AA diameter in a magnetic field of arbitrary angle. We consider the magnetocrystalline anisotropy with the biaxial symmetry and that with the tetragonal symmetry. Using the spin-coherent-state path integral, we obtain approximate analytic formulas of the tunneling rates in the small Ï”(=1−H/Hc)\epsilon (=1- H/H_c)-limit for the magnetic field normal to the easy axis (ΞH=π/2\theta_H = \pi/2), for the field opposite to the initial easy axis (ΞH=π\theta_H = \pi), and for the field at an angle between these two orientations (π/2<<ΞH<<π\pi/2 << \theta_H << \pi). In addition, we obtain numerically the tunneling rates for the biaxial symmetry in the full range of the angle ΞH\theta_H of the magnetic field (π/2<ΞH≀π\pi/2 < \theta_H \leq \pi), for the values of \epsilon =0.01 and 0.001.Comment: 25 pages of text (RevTex) and 4 figures (PostScript files), to be published in Phys. Rev.

    Relativistic Generalization of the Gamow Factor for Fermion Pair Production or Annihilation

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    In the production or annihilation of a pair of fermions, the initial-state or final-state interactions often lead to significant effects on the reaction cross sections. For Coulomb-type interactions, the Gamow factor has been traditionally used to take into account these effects. However the Gamow factor needs to be modified when the magnitude of the coupling constant or the relative velocity of two particles increases. We obtain the relativistic generalization of the Gamow factor in terms of the overlap of the Feynman amplitude with the relativistic wave function of two fermions with an attractive Coulomb-type interaction. An explicit form of the corrective factor is presented for the spin-singlet S-wave state. While the corrective factor approaches the Gamow factor in the non-relativistic limit, we found that the Gamow factor significantly over-estimates the effects when the coupling constant or the velocity is large.Comment: 16 pages, 4 figures in LaTe
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