Core-collapse Supernova Constraint on the Origin of Sterile Neutrino Dark Matter via Neutrino Self-interactions

Novel neutrino self-interaction can open up viable parameter space for therelic abundance of sterile-neutrino dark matter (S$\nu$DM). In this work, weconstrain the relic target using core-collapse supernova which features thesame fundamental process and a similar environment to the early universe erawhen S$\nu$DM is dominantly produced. We present a detailed calculation of theeffects of a massive scalar mediated neutrino self-interaction on the supernovacooling rate, including the derivation of the thermal potential in the presenceof non-zero chemical potentials from plasma species. Our results demonstratethat the supernova cooling argument can cover the neutrino self-interactionparameter space that complements terrestrial and cosmological probes.<br

Security and Privacy Issues in Wireless Mesh Networks: A Survey

This book chapter identifies various security threats in wireless mesh network (WMN). Keeping in mind the critical requirement of security and user privacy in WMNs, this chapter provides a comprehensive overview of various possible attacks on different layers of the communication protocol stack for WMNs and their corresponding defense mechanisms. First, it identifies the security vulnerabilities in the physical, link, network, transport, application layers. Furthermore, various possible attacks on the key management protocols, user authentication and access control protocols, and user privacy preservation protocols are presented. After enumerating various possible attacks, the chapter provides a detailed discussion on various existing security mechanisms and protocols to defend against and wherever possible prevent the possible attacks. Comparative analyses are also presented on the security schemes with regards to the cryptographic schemes used, key management strategies deployed, use of any trusted third party, computation and communication overhead involved etc. The chapter then presents a brief discussion on various trust management approaches for WMNs since trust and reputation-based schemes are increasingly becoming popular for enforcing security in wireless networks. A number of open problems in security and privacy issues for WMNs are subsequently discussed before the chapter is finally concluded.Comment: 62 pages, 12 figures, 6 tables. This chapter is an extension of the author's previous submission in arXiv submission: arXiv:1102.1226. There are some text overlaps with the previous submissio

Effect of alcohol and aldehyde dehydrogenase gene polymorphisms on alcohol-associated hypertension: the Guangzhou Biobank Cohort Study

published_or_final_versio

Exact Analysis of Scaling and Dominant Attractors Beyond the Exponential Potential

By considering the potential parameter $\Gamma$ as a function of another potential parameter $\lambda$[47], We successfully extend the analysis of two-dimensional autonomous dynamical system of quintessence scalar field model to the analysis of three-dimension, which makes us be able to research the critical points of a large number of potentials beyond the exponential potential exactly. We find that there are ten critical points in all, three points $P_{3, 5, 6}$} are general points which are possessed by all quintessence models regardless of the form of potentials and the rest points are closely connected to the concrete potentials. It is quite surprising that, apart from the exponential potential, there are a large number of potentials which can give the scaling solution when the function $f(\lambda)(=\Gamma(\lambda)-1)$ equals zero for one or some values of $\lambda_{*}$ and if the parameter $\lambda_{*}$ also satisfies the condition Eq.(16) or Eq.(17) at the same time. We give the differential equations to derive these potentials $V(\phi)$ from $f(\lambda)$. We also find that, if some conditions are satisfied, the de-Sitter-like dominant point $P_4$ and the scaling solution point $P_9$(or $P_{10}$) can be stable simultaneously but $P_9$ and $P_{10}$ can not be stable simultaneity. Although we survey scaling solutions beyond the exponential potential for ordinary quintessence models in standard general relativity, this method can be applied to other extensively scaling solution models studied in literature[46] including coupled quintessence, (coupled-)phantom scalar field, k-essence and even beyond the general relativity case $H^2 \propto\rho_T^n$. we also discuss the disadvantage of our approach.Comment: 16 pages,no figure, this new revision has taken the suggestions from CQG referees and has been accepted for publication in Classical and Quantum Gravit

Localized Epigenetic Changes Induced by DH Recombination Restricts Recombinase to DJH Junctions

Immunoglobulin heavy chain (Igh) genes are assembled by sequential rearrangements of diversity (DH) and variable (VH) gene segments. Three critical constraints govern VH recombination. These include timing (VH recombination follows DH recombination), precision (VHs recombine only to DJH junctions) and allele specificity (VH recombination is restricted to DJH recombined alleles). We provide a model for these universal features of VH recombination. Analyses of DJH recombined alleles revealed that DJH junctions were selectively epigenetically marked, became nuclease sensitive and bound RAG proteins, thereby permitting DH-associated recombination signal sequences to initiate the second step of Igh gene assembly. We propose that VH recombination is precise because these changes did not extend to germline DH gene segments located 5′ of the DJH junction

Coupled Quintessence and Phantom Based On a Dilaton

Based on dilatonic dark energy model, we consider two cases: dilaton field with positive kinetic energy(coupled quintessence) and with negative kinetic energy(phantom). In the two cases, we investigate the existence of attractor solutions which correspond to an equation of state parameter $\omega=-1$ and a cosmic density parameter $\Omega_\sigma=1$. We find that the coupled term between matter and dilaton can't affect the existence of attractor solutions. In the Mexican hat potential, the attractor behaviors, the evolution of state parameter $\omega$ and cosmic density parameter $\Omega$, are shown mathematically. Finally, we show the effect of coupling term on the evolution of $X(\frac{\sigma}{\sigma_0})$ and $Y(\frac{\dot{\sigma}}{\sigma^2_0})$ with respect to $N(lna)$ numerically.Comment: 9 pages, 11 figures, some references and Journal-ref adde

Ashtekar's New Variables and Positive Energy

We discuss earlier unsuccessful attempts to formulate a positive gravitational energy proof in terms of the New Variables of Ashtekar. We also point out the difficulties of a Witten spinor type proof. We then use the special orthonormal frame gauge conditions to obtain a locally positive expression for the New Variables Hamiltonian and thereby a ``localization'' of gravitational energy as well as a positive energy proof.Comment: 12 pages Plain Te

Optimal phase estimation in quantum networks

We address the problem of estimating the phase phi given N copies of the phase rotation u(phi) within an array of quantum operations in finite dimensions. We first consider the special case where the array consists of an arbitrary input state followed by any arrangement of the N phase rotations, and ending with a POVM. We optimise the POVM for a given input state and fixed arrangement. Then we also optimise the input state for some specific cost functions. In all cases, the optimal POVM is equivalent to a quantum Fourier transform in an appropriate basis. Examples and applications are given.Comment: 9 pages, 2 figures; this is an extended version of arXiv:quant-ph/0609160. v2: minor corrections in reference

Reconstructing the properties of dark energy from recent observations

We explore the properties of dark energy from recent observational data, including the Gold Sne Ia, the baryonic acoustic oscillation peak from SDSS, the CMB shift parameter from WMAP3, the X-ray gas mass fraction in cluster and the Hubble parameter versus redshift. The $\Lambda CDM$ model with curvature and two parameterized dark energy models are studied. For the $\Lambda CDM$ model, we find that the flat universe is consistent with observations at the $1\sigma$ confidence level and a closed universe is slightly favored by these data. For two parameterized dark energy models, with the prior given on the present matter density, $\Omega_{m0}$, with $\Omega_{m0}=0.24$, $\Omega_{m0}=0.28$ and $\Omega_{m0}=0.32$, our result seems to suggest that the trend of $\Omega_{m0}$ dependence for an evolving dark energy from a combination of the observational data sets is model-dependent.Comment: 16 pages, 15 figures, To appear in JCA