26,399 research outputs found

    The Measure for the Multiverse and the Probability for Inflation

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    We investigate the measure problem in the framework of inflationary cosmology. The measure of the history space is constructed and applied to inflation models. Using this measure, it is shown that the probability for the generalized single field slow roll inflation to last for NN e-folds is suppressed by a factor exp(3N)\exp(-3N), and the probability for the generalized nn-field slow roll inflation is suppressed by a much larger factor exp(3nN)\exp(-3nN). Some non-inflationary models such as the cyclic model do not suffer from this difficulty.Comment: 16 page

    Eternal Chaotic Inflation is Prohibited by Weak Gravity Conjecture

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    We investigate whether the eternal chaotic inflation can be achieved when the weak gravity conjecture is taken into account. We show that even the assisted chaotic inflation with potential λϕ4\lambda\phi^4 or m2ϕ2m^2\phi^2 can not be eternal. The effective field theory description for the inflaton field breaks down before inflation reaches the eternal regime. We also find that the total number of e-folds is still bounded by the inflationary entropy for the assisted inflation.Comment: 10 page

    Holographic dark energy in a universe with spatial curvature and massive neutrinos: a full Markov Chain Monte Carlo exploration

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    In this paper, we report the results of constraining the holographic dark energy model with spatial curvature and massive neutrinos, based on a Markov Chain Monte Carlo global fit technique. The cosmic observational data include the full WMAP 7-yr temperature and polarization data, the type Ia supernova data from Union2.1 sample, the baryon acoustic oscillation data from SDSS DR7 and WiggleZ Dark Energy Survey, and the latest measurements of H0H_0 from HST. To deal with the perturbations of dark energy, we adopt the parameterized post-Friedmann method. We find that, for the simplest holographic dark energy model without spatial curvature and massive neutrinos, the phenomenological parameter c<1c<1 at more than 4σ4\sigma confidence level. The inclusion of spatial curvature enlarges the error bars and leads to c<1c<1 only in about 2.5σ2.5\sigma range; in contrast, the inclusion of massive neutrinos does not have significant influence on cc. We also find that, for the holographic dark energy model with spatial curvature but without massive neutrinos, the 3σ3\sigma error bars of the current fractional curvature density Ωk0\Omega_{k0} are still in order of 10210^{-2}; for the model with massive neutrinos but without spatial curvature, the 2σ2\sigma upper bound of the total mass of neutrinos is mν<0.48\sum m_{\nu} < 0.48 eV. Moreover, there exists clear degeneracy between spatial curvature and massive neutrinos in the holographic dark energy model, which enlarges the upper bound of mν\sum m_{\nu} by more than 2 times. In addition, we demonstrate that, making use of the full WMAP data can give better constraints on the holographic dark energy model, compared with the case using the WMAP ``distance priors''.Comment: 21 pages, 10 figures; major revision; new figures and discussions added; accepted by JCA

    Curvaton Dynamics and the Non-Linearity Parameters in Curvaton Model

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    We investigate the curvaton dynamics and the non-linearity parameters in curvaton model with potential slightly deviating from the quadratic form in detail. The non-linearity parameter gNLg_{NL} will show up due to the curvaton self-interaction. We also point out that the leading order of non-quadratic term in the curvaton potential can be negative, for example in the axion-type curvaton model. If a large positive gNLg_{NL} is detected, the axion-type curvaton model will be preferred.Comment: 14 pages, 4 figures; refs adde

    Effects of diets containing different concentrations of energy on growth performance and carcass traits of geese from 28 to 70 days of age

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    Supplementation of dietary energy could reduce daily feed intake, decrease the feed/gain ratio, and increase intramuscular fat content. Based on broken-line regression analysis, the optimal concentrations of dietary energy for Sichuan White geese from 28 to 70 d was 12.56 MJ AME/ kg DM for minimum ADFI and 13.09 MJ AME/kg DM for optimum FGR, respectively

    The Holographic Model of Dark Energy and Thermodynamics of Non-Flat Accelerated Expanding Universe

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    Motivated by recent results on non-vanishing spatial curvature \cite{curve} we employ the holographic model of dark energy to investigate the validity of first and second laws of thermodynamics in non-flat (closed) universe enclosed by apparent horizon RAR_A and the event horizon measured from the sphere of horizon named LL. We show that for the apparent horizon the first law is roughly respected for different epochs while the second laws of thermodynamics is respected while for LL as the system's IR cut-off first law is broken down and second law is respected for special range of deceleration parameter. It is also shown that at late-time universe LL is equal to RAR_A and the thermodynamic laws are hold, when the universe has non-vanishing curvature. Defining the fluid temperature to be proportional to horizon temperature the range for coefficient of proportionality is obtained provided that the generalized second law of thermodynamics is hold.Comment: 12 pages, no figure, abstract and text extended, references added, accepted for publication in JCA

    Integrative analyses of transcriptome sequencing identify novel functional lncRNAs in esophageal squamous cell carcinoma.

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    Long non-coding RNAs (lncRNAs) have a critical role in cancer initiation and progression, and thus may mediate oncogenic or tumor suppressing effects, as well as be a new class of cancer therapeutic targets. We performed high-throughput sequencing of RNA (RNA-seq) to investigate the expression level of lncRNAs and protein-coding genes in 30 esophageal samples, comprised of 15 esophageal squamous cell carcinoma (ESCC) samples and their 15 paired non-tumor tissues. We further developed an integrative bioinformatics method, denoted URW-LPE, to identify key functional lncRNAs that regulate expression of downstream protein-coding genes in ESCC. A number of known onco-lncRNA and many putative novel ones were effectively identified by URW-LPE. Importantly, we identified lncRNA625 as a novel regulator of ESCC cell proliferation, invasion and migration. ESCC patients with high lncRNA625 expression had significantly shorter survival time than those with low expression. LncRNA625 also showed specific prognostic value for patients with metastatic ESCC. Finally, we identified E1A-binding protein p300 (EP300) as a downstream executor of lncRNA625-induced transcriptional responses. These findings establish a catalog of novel cancer-associated functional lncRNAs, which will promote our understanding of lncRNA-mediated regulation in this malignancy
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