Ionizing radiation fluctuations and large-scale structure in the Lyman-alpha forest

We investigate the large-scale inhomogeneities of the hydrogen ionizing radiation field in the Universe at redshift z=3. Using a raytracing algorithm, we simulate a model in which quasars are the dominant sources of radiation. We make use of large scale N-body simulations of a LambdaCDM universe, and include such effects as finite quasar lifetimes and output on the lightcone, which affects the shape of quasar light echoes. We create Lya forest spectra that would be generated in the presence of such a fluctuating radiation field, finding that the power spectrum of the Lya forest can be suppressed by as much as 15 % for modes with k=0.05-1 Mpc/h. This relatively small effect may have consequences for high precision measurements of the Lya power spectrum on larger scales than have yet been published. We also investigate another radiation field probe, the cross-correlation of quasar positions and the Lya forest. For both quasar lifetimes which we simulate (10^7 yr and 10^8 yr), we expect to see a strong decrease in the Lya absorption close to other quasars (the ``foreground'' proximity effect). We then use data from the Sloan Digital Sky Survey First Data Release to make an observational determination of this statistic. We find no sign of our predicted lack of absorption, but instead increased absorption close to quasars. If the bursts of radiation from quasars last on average < 10^6 yr, then we would not expect to be able to see the foreground effect. However, the strength of the absorption itself seems to be indicative of rare objects, and hence much longer total times of emission per quasar. Variability of quasars in bursts with timescales > 10^4yr and < 10^6 yr could reconcile these two facts.Comment: Submitted to ApJ, 21 pages, 17 postscript figures, emulateapj.st

Spin- and isospin-polarized states of nuclear matter in the Dirac-Brueckner-Hartree-Fock model

Spin-polarized isospin asymmetric nuclear matter is studied within the Dirac-Brueckner-Hartree-Fock approach. After a brief review of the formalism, we present and discuss the self-consistent single-particle potentials at various levels of spin and isospin asymmetry. We then move to predictions of the energy per particle, also under different conditions of isospin and spin polarization. Comparison with the energy per particle in isospin symmetric or asymmetric unpolarized nuclear matter shows no evidence for a phase transition to a spin ordered state, neither ferromagnetic nor antiferromagnetic.Comment: 8 pages, 6 figure

Microscopic three-body force for asymmetric nuclear matter

Brueckner calculations including a microscopic three-body force have been extended to isospin asymmetric nuclear matter. The effects of the three-body force on the equation of state and on the single-particle properties of nuclear matter are discussed with a view to possible applications in nuclear physics and astrophysics. It is shown that, even in the presence of the three-body force, the empirical parabolic law of the energy per nucleon vs isospin asymmetry $\beta=(N-Z)/A$ is fulfilled in the whole asymmetry range $0\le\beta\le 1$ up to high densities. The three-body force provides a strong enhancement of symmetry energy increasing with the density in good agreement with relativistic approaches. The Lane's assumption that proton and neutron mean fields linearly vary vs the isospin parameter is violated at high density in the presence of the three-body force. Instead the momentum dependence of the mean fields is rather insensitive to three body force which brings about a linear isospin deviation of the neutron and proton effective masses. The isospin effects on multifragmentation events and collective flows in heavy-ion collisions are briefly discussed along with the conditions for direct URCA processes to occur in the neutron-star cooling.Comment: 11 pages, 7 figure

International Legal Review of the Relationship between International Tax Law and National Tax Sovereignty: Theoretical Foundation and Development Practices

By examining their theoretical basis and exercising practice relationship between national sovereignty and international tax law, it is demonstrated that the international tax law results from the coordination to exercise national sovereignty in the international law. Given the modern connotation of national sovereignty and exercising practices of international tax treaties in the international law, it is reasoned that “the international tax treaty is a kind of limitation or mitigation to national tax sovereignty” is a false pseudo-proposition; International tax regime has been established on the international law level and constitutes a part of customary international law, which is of great significance; No country has the law-making capacity or its national interest dives in the international law to change the existing international tax regime. Taking account of the exercise of the national tax sovereignty under the backdrop of the latest development practices in international tax law, it can be found that international tax cooperation makes the exercise of national tax sovereignty increase other than decrease; Countries’ intensive actions to safeguard their own international taxation interests strengthen the exercise of their national tax sovereignty; New international tax topics, such as Carbon tariff and environmental taxes, will accelerate law-making revolution of international law in the field of international tax law, and thus makes the exercise of national tax sovereignty to be unified.preprin

Institutional Fragmentation and the Ontological 'Ethos' of International Law as a Legal System in a World Society

In the “institutional fragmentation of international IP law” debate, the analogy between international law and national legal systems, as the theoretical premise of the “institutional fragmentation” language, fails for the lack of “relevant similarity”. And secondly, the ontological “ethos” of international law, which are the inherent virtues of international law-making and implementation, regime evolution and interaction in this world society, could rectify the chaos of this rhetoric of “institutional fragmentation” and illuminate the understated benefits as well as rationalities of institutional fragmentation. The “post-ontological era” is not coming yet for this “institutional fragmentation” debate, and the “institutional fragmentation” is the “new normal”. Thirdly, The fundamental contradiction contained in this “institutional fragmentation of international law” debate is between the specialization of international law (the “functional approach” of modern international law’s development, as the endogenous factors) and top-down systematic theoretical conception of international law (international law as a legal system, as the exogenous factors). The junction of those forces is the “concerns on the legitimacy of international law” against national legal systems in a world society. Fourthly, from analogical reasoning to ontological “ethos”, there is a “paradigm shift” from the traditional “top-down” global governance paradigm (which is associated with analogical reasoning and hierarchical solutions to “regime complex”) to a “bottom-up” approach with more ontological and inside-out-looking (which could better grasp and understand the dynamics and pulse of regime interaction and evolution). This fundamental change enables those arguments thereafter on the regime interactions and evolutions have totally different theoretical departures, journeys and destinations. Namely, it is more appropriate to ask “what is the status quo, and how to understand it in a historical, relational, structural and holographic way; through analyses of underlying reasons and rules, how will the landscape develop in the future and what could or should be done if there are certain preferences” with a realistic “bottom-up approach” in consideration of the “law of universal gravitation” and the structure of “tensional integrity” in this “regime interaction” perspective, rather than constructively and blindly ask “how to better manage the existing regimes and their collisions, and what are those workable (hierarchical or top-down-governance) solutions” from the perspective of “top-down” governance with cognitive path-dependence.preprin

Extended quark mean-field model for neutron stars

We extend the quark mean-field (QMF) model to strangeness freedom to study the properties of hyperons ($\Lambda,\Sigma,\Xi$) in infinite baryon matter and neutron star properties. The baryon-scalar meson couplings in the QMF model are determined self-consistently from the quark level, where the quark confinement is taken into account in terms of a scalar-vector harmonic oscillator potential. The strength of such confinement potential for $u,d$ quarks is constrained by the properties of finite nuclei, while the one for $s$ quark is limited by the properties of nuclei with a $\Lambda$ hyperon. These two strengths are not same, which represents the SU(3) symmetry breaking effectively in the QMF model. Also, we use an enhanced $\Sigma$ coupling with the vector meson, and both $\Sigma$ and $\Xi$ hyperon potentials can be properly described in the model. The effects of the SU(3) symmetry breaking on the neutron star structures are then studied. We find that the SU(3) breaking shifts earlier the hyperon onset density and makes hyperons more abundant in the star, in comparisons with the results of the SU(3) symmetry case. However, it does not affect much the star's maximum mass. The maximum masses are found to be $1.62 M_{\odot}$ with hyperons and $1.88 M_{\odot}$ without hyperons. The present neutron star model is shown to have limitations on explaining the recently measured heavy pulsar.Comment: 7 pages, 7 figures, Phys. Rev. C (2014) accepte