An Interacting Two-Fluid Scenario for Quintom Dark Energy

The Quintom dark energy is a proposal that explains the recent observations that mildly favor the equation of state of dark energy ω crossing -1 near the past. The Quintom model is often constructed by two scalar fields, where one is the quintessence feld and another is the phantom field. The cosmological implication of the coupling of the two fields of the dark energy is out of question worth investigating. However, the consideration of the coupling in the field scenario is somewhat complex thus we propose an interacting two-fluid Quintom scenario for simplicity. The interaction between the two components is parametrized by a constant 71 in this scenario. The cosmological implications of this parametrization are investigated in detail in this paper. Also, a diagnostic for this model is performed by using the statefinder pairs {s, r} and {q, r}.

Some Magnetized Bulk Viscous String Cosmological Models in Cylindrically Symmetric Inhomogeneous Universe with Variable Λ-Term

Some cylindrically symmetric inhomogeneous viscous fluid string cosmological models with magnetic field and cosmological term A varying with time are investigated. To get the deterministic solution, it has been assumed that the expansion （θ） in the model is proportional to the eigen value σ^11 of the shear tensor σ^ij. The value of cosmological constant for the model is found to be small and positive, which is supported by the results from recent supernovae Ia observations. The effect of bulk viscosity is to produce a change in perfect fluid and hence exhibits essential influence on the character of the solution. The physical and geometric properties of the models are also discussed in presence and absence of magnetic field.

Phantom-Like Effects on Warped DGP Brane

We study phantom-like effect on the DGP brane embedded in a five-dimensional AdS bulk. We show that this effect can be realized without phantom matter on this warped DGP brahe. We investigate the role played by the bulk cosmological constant on the phantom-like effect on the brane and we show that it tends to reduce this effect. Also, warped compactification of the bulk manifold increases the values of the effective and total equation of state parameters of the model relative to the case with Minkowski bulk. We extend our study to the ease that induced curvature on the brahe is modified in the spirit of the f（R）-gravity.

In Tempore Belli： Reflections on the Sense of the Universal in George Crumb＇s Music of the Vietnam War

This paper proposes new ways to understand the sense of universality in music through a reflection and analysis of George Crumb＇s Black Angels （Images 1）： Thirteen lmages from the Dark Land, one of the defining musical expressions of the Vietnam War era. It centers on an analysis of the relationship of the body/self to an ＂ecology of war＂ produced through Crumb＇s music that renders these selves indistinct within this musical geography. The selves that inhabit Black Angels could be that of anybody in particular since Crumb seeks to invoke in his music the primeval experience of terror that inhabits in all of us as the inheritors of mankind＇s violence. This sense of the universal militates against the desirable qualities of popular music that rely on the production of autonomous and singular selves that make the distinction between enemy and friend possible and distinct. We focus on Crumb＇s use of archaisms, his construction of time in this piece, and the author＇s overall purpose to invoke a time of war rather than to reflect the conditions of war, in order to delineate the contours of the universal time and space producing the undifferentiated primeval self of war. We conclude that although Crumb＇s rejection of the national self deprives the piece of a salient place in the popular cannon of the war, it has left an intellectual legacy on the times of the Vietnam War that deserves to be preserved.

Uranium comminution age responds to erosion rate semiquantitatively

Here we present(^(234)U/^(238)U)data from river sediments collected on the Tibetan Plateau.The(^(234)U/^(238)U)ratios of a specific grain size fraction show good correlation with erosion rates,which were determined by in-situ–produced cosmogenic nuclides.This correlation has previously been observed in a wide range of geomorphic settings,suggesting that(^(234)U/^(238)U)ratios of fluvial sediments have great potential to quantify erosion rates.

A Plane-Symmetric Inhomogeneous Cosmological Model of Perfect Fluid Distribution with Electromagnetic Field Ⅰ

A plane-symmetric inhomogeneous cosmological model of perfect fluid distribution with electro-magnetic field is obtained. F12 is the non-vanishing component of electromagnetic field tensor. To get a deterministic solution, we assume the free gravitational field is Petrov type-Ⅱ non-degenerate. Some physical and geometric properties of the model are also discussed.

虎低吟,龙抬头

多年前，藤泽秀行曾这样评价有“宇宙流”之称的武官正树：100年后我们这些人的棋谱都会失传，只有他的棋将流传下去，如今秀行先生的论断在棋迷中似乎得到了验证——尽管已经很长时间没有过任何拿得出手的战绩．但武官一直拥有着比李昌镐还多的铁杆棋迷。有意思的是不久前有人给当年日本的几位超一流高手做了一次盘点，结果发现武宫竟是其中胜率最低的！人们喜爱“宇宙流”的原因是什么昵？

Detection of spectral hardenings in cosmic-ray boron-to-carbon and boron-to-oxygen flux ratios with DAMPE

Boron nuclei in cosmic rays(CRs)are believed to be mainly produced by the fragmentation of heavier nuclei,such as carbon and oxygen,via collisions with the interstellar matter.Therefore,the boron-tocarbon flux ratio(B/C)and the boron-to-oxygen flux ratio(B/O)are very essential probes of the CR propagation.The energy dependence of the B/C ratio from previous balloon-borne and space-based experiments can be well described by a single power-law up to about 1 TeV/n within uncertainties.This work reports direct measurements of B/C and B/O in the energy range from 10 Ge V/n to 5.6 TeV/n with 6 years of data collected by the Dark Matter Particle Explorer,with high statistics and well controlled systematic uncertainties.The energy dependence of both the B/C and B/O ratios can be well fitted by a broken power-law model rather than a single power-law model,suggesting the existence in both flux ratios of a spectral hardening at about 100 Ge V/n.The significance of the break is about 5.6σand 6.9σfor the GEANT4 simulation,and 4.4σand 6.9σfor the alternative FLUKA simulation,for B/C and B/O,respectively.These results deviate from the predictions of conventional turbulence theories of the interstellar medium(ISM),which point toward a change of turbulence properties of the ISM at different scales or novel propagation effects of CRs,and should be properly incorporated in the indirect detection of dark matter via anti-matter particles.

Time-machine in Perfect Fluid Cosmologies

This letter investigates the time-machine problem in perfect fluid cosmologies. It solves the Einstein’s field equations with the energy-momentum tensors for perfect fluid and constructs a class of time-machine solutions, by which the time-machine problem in the perfect fluid cosmologies is solved.

Fast jet proper motion discovered in a blazar at z=4.72

High-resolution observations of high-redshift(z > 4) radio quasars offer a unique insight into jet kinematics at early cosmological epochs, as well as constraints on cosmological model parameters.Due to the general weakness of extremely distant objects and the apparently slow structural changes caused by cosmological time dilation, only a couple of high-redshift quasars(HRQs) have been studied with parsec-scale resolutions, and with limited number of observing epochs. Here we report on very long baseline interferometry(VLBI) observations of a high-redshift blazar J1430 + 4204(z=4.72) in the 8 GHz frequency band at five different epochs spanning 22 years. The source shows a compact core–jet structure with two jet components being identified within 3 milli-arcsecond(mas) scale. The long time span and multiple-epoch data allow for the kinematic studies of the jet components. That results in a jet proper motion of μ(J1) = 0.017 ± 0.002 mas a^-1 and μ(J2) = 0.156 ± 0.015 mas a^-1, respectively. For the fastest-moving outer jet component J2, the corresponding apparent transverse speed is (19.5 ± 1.9) c.The inferred bulk jet Lorentz factor C=14.6 ± 3.8 and viewing angle θ=2.2°± 1.6°indicate highly relativistic beaming. The Lorentz factor and apparent proper motion are the highest measured to date among the z > 4 jetted radio sources, while the jet kinematics is still consistent with the cosmological interpretation of quasar redshifts.

Effects of f(R) Model on Dynamics of Axial Shear-Free Dissipative Fluids

We present a general analysis on non-static axial system with dissipative shear-free anisotropic fluid using polynomial inflationary f(R) model.We study the effects of dissipation on the dynamics of geodesic matter distribution.This leads the system either to rotation-free or expansion-free but not both simultaneously under geodesic condition.It is found that the system preserves its symmetry in both cases.For the rotation-free case,when there is no dissipation and Ricci scalar is constant,the axial system reduces to FRW universe model.This is exactly the same result obtained in general relativity.