5,825 research outputs found

    Implications of Fermi-LAT observations on the origin of IceCube neutrinos

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    The IceCube (IC) collaboration recently reported the detection of TeV-PeV extraterrestrial neutrinos whose origin is yet unknown. By the photon-neutrino connection in pppp and pγp\gamma interactions, we use the \fermi-LAT observations to constrain the origin of the IC detected neutrinos. We find that Galactic origins, i.e., the diffuse Galactic neutrinos due to cosmic ray (CR) propagation in the Milky Way, and the neutrinos from the Galactic point sources, may not produce the IC neutrino flux, thus these neutrinos should be of extragalactic origin. Moreover, the extragalactic gamma-ray bursts (GRBs) may not account for the IC neutrino flux, the jets of active galactic nuclei may not produce the IC neutrino spectrum, but the starburst galaxies (SBGs) may be promising sources. As suggested by the consistency between the IC detected neutrino flux and the Waxman-Bahcall bound, GRBs in SBGs may be the sources of both the ultrahigh energy, >1019>10^{19}eV, CRs and the 11001-100~PeV CRs that produce the IC detected TeV-PeV neutrinos.Comment: JCAP accepted version; 8 pages, 2 figs; discussion on blazar origin added; conclusion unchange

    DKA patient with blood-sugar level 68.14mmol/L was not in a coma: A case report

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    目的探讨分析1 例糖尿病酮症酸中毒患者,未昏迷的原因,为临床同类疾病的诊疗提供参考。方法回顾分析笔者收治的1 例血糖68.14mmol/L 的糖尿病酮症酸中毒患者的诊疗资料。结果与结论血糖缓慢升高的血浆有效渗透压缓慢升高患者,可出现不昏迷情况,临床诊疗中应予以重视。Objective: To analyze the reason why DKA (Diabetic ketoacidosis) patient with blood-sugar level 68.14mmol/L was not in a coma, and provide a reference to clinical treatment for diseases of the same type. Method: Retrospectively analyzed the data of DKA patient with blood-sugar level 68.14mmol/L. Results and Conclusion: patients whose plasma effective osmotic pressure increases slowly may not be in a coma, which need be emphasized in clinical treatment.

    Strong Cosmic Censorship in Charged de Sitter spacetime with Scalar Field Non-minimally Coupled to Curvature

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    We examine the stability and the strong cosmic censorship in the Reissner-Nordstrom-de Sitter (RN-dS) black hole by investigating the evolution of a scalar field non-minimally coupled to the curvature. We find that when the coupling parameter is negative, the RN-dS black hole experiences instability. The instability disappears when the coupling parameter becomes non-negative. With the increase of the coupling parameter, the violation of the strong cosmic censorship occurs at a larger critical charge ratio. But such an increase of the critical charge is suppressed by the increase of the cosmological constant. Different from the minimal coupling situation, it is possible to accommodate β1\beta\ge1 in the near extremal black hole when the scalar field is non-minimally coupled to curvature. The increase of the cosmological constant can allow β1\beta\ge1 to be satisfied for even smaller value of the coupling parameter. The existence of β1\beta\ge1 implies that the resulting curvature can continuously cross the Cauchy horizon.Comment: 14 pages, 4 figures, 5 table

    Signature of Pseudo Nambu-Goldstone Higgs boson in its Decay

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    If the Higgs boson is a pseudo Nambu-Goldstone boson (PNGB), the hZγhZ\gamma contact interaction induced by the O(p4)\mathcal{O}(p^4) invariants of the non-linear sigma model is free from its nonlinearity effects. The process hZγh\rightarrow Z\gamma can be used to eliminate the universal effects of heavy particles, which can fake the nonlinearity effects of the PNGB Higgs boson in the process hVVh\rightarrow V^*V (V=W±V=W^\pm,\ ZZ). We demonstrate that the ratio of the signal strength of hZγh\rightarrow Z\gamma and hVVh\rightarrow V^*V is good to distinguish the signature of the PNGB Higgs boson from Higgs coupling deviations

    The thermal evolution of nuclear matter at zero temperature and definite baryon number density in chiral perturbation theory

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    The thermal properties of cold dense nuclear matter are investigated with chiral perturbation theory. The evolution curves for the baryon number density, baryon number susceptibility, pressure and the equation of state are obtained. The chiral condensate is calculated and our result shows that when the baryon chemical potential goes beyond 1150MeV1150 \mathrm{MeV}, the absolute value of the quark condensate decreases rapidly, which indicates a tendency of chiral restoration.Comment: 17 pages, 9 figures, revtex

    A Model of Two-Way Selection System for Human Behavior

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    We propose a model of two-way selection system. It appears in the processes like choosing a mate between men and women, making contracts between job hunters and recruiters, and trading between buyers and sellers. In this paper, we propose a model of two-way selection system, and present its analytic solution for the expectation of successful matching total and the regular pattern that the matching rate trends toward an inverse proportion to either the ratio between the two sides or the ratio of the state total to the smaller people number. The proposed model is verified by empirical data of the matchmaking fairs. Results indicate that the model well predicts this typical real-world two- way selection behavior to the bounded error extent, thus it is helpful for understanding the dynamics mechanism of the real-world two-way selection system.Comment: 8 pages, 4 figure

    Characteristics of profiles of gamma-ray burst pulses associated with the Doppler effect of fireballs

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    In this paper, we derive in a much detail the formula of count rates, in terms of the integral of time, of gamma-ray bursts in the framework of fireballs, where the Doppler effect of the expanding fireball surface is the key factor to be concerned. Effects arising from the limit of the time delay due to the limited regions of the emitting areas in the fireball surface and other factors are investigated. Our analysis shows that the formula of the count rate of fireballs can be expressed as a function of τ\tau which is the observation time scale relative to the dynamical time scale of the fireball. The profile of light curves of fireballs depends only on the relative time scale, entirely independent of the real time scale and the real size of the objects. It displays in detail how a cutoff tail, or a turn over, feature (called a cutoff tail problem) in the decay phase of a light curve can be formed. This feature is a consequence of a hot spot in the fireball surface, moving towards the observer, and was observed in a few cases previously. By performing fits to the count rate light curves of six sample sources, we show how to obtain some physical parameters from the observed profile of the count rate of GRBs. In addition, the analysis reveals that the Doppler effect of fireballs could lead to a power law relationship between the FWHMFWHM of pulses and energy, which were observed previously by many authors.Comment: 38 pages, 10 figures; accepted for publication in ApJ (10 December 2004, v617
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