622 research outputs found
Rolling in the Modulated Reheating Scenario
In the modulated reheating scenario, the field that drives inflation has a
spatially varying decay rate, and the resulting inhomogeneous reheating process
generates adiabatic perturbations. We examine the statistical properties of the
density perturbations generated in this scenario. Unlike earlier analyses, we
include the dynamics of the field that determines the inflaton decay rate. We
show that the dynamics of this modulus field can significantly alter the
amplitude of the power spectrum and the bispectrum, even if the modulus field
has a simple potential and its effective mass is smaller than the Hubble rate.
In some cases, the evolution of the modulus amplifies the non-Gaussianity of
the perturbations to levels that are excluded by recent observations of the
cosmic microwave background. Therefore, a proper treatment of the modulus
dynamics is required to accurately calculate the statistical properties of the
perturbations generated by modulated reheating.Comment: 27 pages, 11 figures: minor changes made to match version in JCA
Supersymmetry preserving and breaking degenerate vacua, and radiative moduli stabilization
We propose a new type of moduli stabilization scenario where the
supersymmetric and supersymmetry-breaking minima are degenerate at the leading
level. The inclusion of the loop-corrections originating from the matter fields
resolves this degeneracy of vacua. Light axions are predicted in one of our
models.Comment: 18 pages, 14 figure
Constraints on small-field axion inflation
We study general class of small-field axion inflations which are the mixture
of polynomial and sinusoidal functions suggested by the natural and axion
monodromy inflations. The axion decay constants leading to the successful axion
inflations are severely constrained in order not to spoil the Big-Bang
nucleosynthesis and overproduce the isocurvature perturbation originating from
the QCD axion. We in turn find that the cosmologically favorable axion decay
constants are typically of order the grand unification scale or the string
scale which is consistent with the prediction of closed string axions.Comment: 17 pages, 6 figures; v2 published versio
An Extended ISM for Globally Multimodal Function Optimization by Genetic Algorithms
When attempting to optimize a function where exists several big-valley structures, conventional GAs often fail to find the global optimum. Innately Split Model (ISM) is a framework of GAs, which is designed to avoid this phenomenon called UV-Phenomenon. However, ISM doesn't care about previously-searched areas by the past populations. Thus, it is possible that populations of ISM waste evaluation cost for redundant searches reaching previously-found optima. In this paper, we introduce Extended ISM (EISM) that uses search information of past populations as trap to suppress overlapping searches. To show performance of EISM, we apply it to some test functions, and analyze the behavior
Effective Interaction of Electroweak-Interacting Dark Matter with Higgs Boson and Its Phenomenology
We study phenomenology of electroweak-interacting fermionic dark matter (DM)
with a mass of GeV. Constructing the effective Lagrangian
that describes the interactions between the Higgs boson and the SU(2)
isospin multiplet fermion, we evaluate the electric dipole moment (EDM) of
electron, the signal strength of Higgs boson decay to two photons and the
spin-independent elastic-scattering cross section with proton. As
representative cases, we consider the SU(2) triplet fermions with
zero/nonzero hypercharges and SU(2) doublet fermion. It is found that the
electron EDM gives stringent constraints on those model parameter spaces. In
the cases of the triplet fermion with zero hypercharge and the doublet fermion,
the Higgs signal strength does not deviate from the standard model prediction
by more than a few % once the current DM direct detection constraint is taken
into account, even if the CP violation is suppressed. On the contrary,
- % deviation may occur in the case of the triplet fermion
with nonzero hypercharge. Our representative scenarios may be tested by the
future experiments.Comment: 13 pages, 5 figures. Version accepted for publication in Phys. Lett.
Solution Structure of IseA, an Inhibitor Protein of DL-Endopeptidases from Bacillus subtilis, Reveals a Novel Fold with a Characteristic Inhibitory Loop
In Bacillus subtilis, LytE, LytF, CwlS, and CwlO are vegetative autolysins, DL-endopeptidases in the NlpC/P60 family, and play essential roles in cell growth and separation. IseA (YoeB) is a proteinaceous inhibitor against the DL-endopeptidases, peptidoglycan hydrolases. Overexpression of IseA caused significantly long chained cell morphology, because IseA inhibits the cell separation DL-endopeptidases post-translationally. Here, we report the first three-dimensional structure of IseA, determined by NMR spectroscopy. The structure includes a single domain consisting of three alpha-helices, one 3(10)-helix, and eight beta-strands, which is a novel fold like a "hacksaw." Noteworthy is a dynamic loop between beta 4 and the 3(10)-helix, which resembles a "blade." The electrostatic potential distribution shows that most of the surface is positively charged, but the region around the loop is negatively charged. In contrast, the LytF active-site cleft is expected to be positively charged. NMR chemical shift perturbation of IseA interacting with LytF indicated that potential interaction sites are located around the loop. Furthermore, the IseA mutants D100K/D102K and G99P/G101P at the loop showed dramatic loss of inhibition activity against LytF, compared with wild-type IseA, indicating that the beta 4-3(10) loop plays an important role in inhibition. Moreover, we built a complex structure model of IseA-LytF by docking simulation, suggesting that the beta 4-3(10) loop of IseA gets stuck deep in the cleft of LytF, and the active site is occluded. These results suggest a novel inhibition mechanism of the hacksaw-like structure, which is different from known inhibitor proteins, through interactions around the characteristic loop regions with the active-site cleft of enzymes.ArticleJOURNAL OF BIOLOGICAL CHEMISTRY. 287(53):44736-44748 (2012)journal articl
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