1,122 research outputs found
Histone crosstalk directed by H2B ubiquitination is required for chromatin boundary integrity
Genomic maps of chromatin modifications have provided evidence for the partitioning of genomes into domains of distinct chromatin states, which assist coordinated gene regulation. The maintenance of chromatin domain integrity can require the setting of boundaries. The HS4 insulator element marks the 3′ boundary of a heterochromatin region located upstream of the chicken β-globin gene cluster. Here we show that HS4 recruits the E3 ligase RNF20/BRE1A to mediate H2B mono-ubiquitination (H2Bub1) at this insulator. Knockdown experiments show that RNF20 is required for H2Bub1 and processive H3K4 methylation. Depletion of RNF20 results in a collapse of the active histone modification signature at the HS4 chromatin boundary, where H2Bub1, H3K4 methylation, and hyperacetylation of H3, H4, and H2A.Z are rapidly lost. A remarkably similar set of events occurs at the HSA/HSB regulatory elements of the FOLR1 gene, which mark the 5′ boundary of the same heterochromatin region. We find that persistent H2Bub1 at the HSA/HSB and HS4 elements is required for chromatin boundary integrity. The loss of boundary function leads to the sequential spreading of H3K9me2, H3K9me3, and H4K20me3 over the entire 50 kb FOLR1 and β-globin region and silencing of FOLR1 expression. These findings show that the HSA/HSB and HS4 boundary elements direct a cascade of active histone modifications that defend the FOLR1 and β-globin gene loci from the pervasive encroachment of an adjacent heterochromatin domain. We propose that many gene loci employ H2Bub1-dependent boundaries to prevent heterochromatin spreading
Role of lepton flavor violating (LFV) muon decay in Seesaw model and LSND
The aim of the work is to study LFV in a newly proposed Seesaw model of
neutrino mass and to see whether it could explain LSND excess. The motivation
of this Seesaw model was that there was no new physics beyond the TeV scale. By
studying \mu \to 3e in this model, it is shown that the upper bound on the
branching ratio requires Higgs mass m_{h} of a new scalar doublet with lepton
number L=-1 needed in the model has to be about 9 TeV. The predicted branching
ratio for \mu \to e\nu_{l}\bar{\nu}_{l} is too small to explain the LSND. PACS:
11.30.Hv, 14.60.PqComment: 05 pages, three figures, the version to appear in PR
Hemodynamic, Functional, and Clinical Responses to Pulmonary Artery Denervation in Patients With Pulmonary Arterial Hypertension of Different Causes: Phase II Results From the Pulmonary Artery Denervation-1 Study
Background—The mechanisms underlying pulmonary arterial hypertension (PAH) are multifactorial. The efficacy of
pulmonary artery denervation (PADN) for idiopathic PAH treatment has been evaluated. This study aimed to analyze the
hemodynamic, functional, and clinical responses to PADN in patients with PAH of different causes.
Methods and Results—Between April 2012 and April 2014, 66 consecutive patients with a resting mean pulmonary arterial
pressure ≥25 mmHg treated with PADN were prospectively followed up. Target drugs were discontinued after the PADN
procedure. Hemodynamic response and 6-minute walk distance were repeatedly measured within the 1 year post PADN
follow-up. The clinical end point was the occurrence of PAH-related events at the 1-year follow-up. There were no PADNrelated
complications. Hemodynamic success (defined as the reduction in mean pulmonary arterial pressure by a minimal
10% post PADN) was achieved in 94% of all patients, with a mean absolute reduction in systolic pulmonary arterial
pressure and mean pulmonary arterial pressure within 24 hours of −10 mmHg and −7 mmHg, respectively. The average
increment in 6-minute walk distance after PADN was 94 m. Worse PAH-related events occurred in 10 patients (15%),
mostly driven by the worsening of PAH (12%). There were 8 (12%) all-cause deaths, with 6 (9%) PAH-related deaths.
Conclusions—PADN was safe and feasible for the treatment of PAH. The PADN procedure was associated with significant
improvements in hemodynamic function, exercise capacity, and cardiac function and with less frequent PAH-related
events and death at 1 year after PADN treatment. Further randomized studies are required to confirm the efficacy of
PADN for PAH
Entropy spectrum of a Kerr anti-de Sitter black hole
The entropy spectrum of a spherically symmetric black hole was derived
without the quasinormal modes in the work of Majhi and Vagenas. Extending this
work to rotating black holes, we quantize the entropy and the horizon area of a
Kerr anti-de Sitter black hole by two methods. The spectra of entropy and area
are obtained via the Bohr-Sommerfeld quantization rule and the adiabatic
invariance in the first way. By addressing the wave function of emitted
(absorbed) particles, the entropy and the area are quantized in the second one.
Both results show that the entropy and the area spectra are equally spaced.Comment: Accepted for publication in The European Physical Journal C, Volume
72, Issue
Renormalization Group Running of Lepton Mixing Parameters in See-Saw Models with Flavor Symmetry
We study the renormalization group running of the tri-bimaximal mixing
predicted by the two typical flavor models at leading order. Although the
textures of the mass matrices are completely different, the evolution of
neutrino mass and mixing parameters is found to display approximately the same
pattern. For both normal hierarchy and inverted hierarchy spectrum, the quantum
corrections to both atmospheric and reactor neutrino mixing angles are so small
that they can be neglected. The evolution of the solar mixing angle
depends on and neutrino mass spectrum, the deviation
from its tri-bimaximal value could be large. Taking into account the
renormalization group running effect, the neutrino spectrum is constrained by
experimental data on in addition to the self-consistency
conditions of the models, and the inverted hierarchy spectrum is disfavored for
large . The evolution of light-neutrino masses is approximately
described by a common scaling factor.Comment: 23 pages, 6figure
Anomaly analysis of Hawking radiation from Kaluza-Klein black hole with squashed horizon
Considering gravitational and gauge anomalies at the horizon, a new method
that to derive Hawking radiations from black holes has been developed by
Wilczek et al. In this paper, we apply this method to non-rotating and rotating
Kaluza-Klein black holes with squashed horizon, respectively. For the rotating
case, we found that, after the dimensional reduction, an effective U(1) gauge
field is generated by an angular isometry. The results show that the gauge
current and energy-momentum tensor fluxes are exactly equivalent to Hawking
radiation from the event horizon.Comment: 15 pages, no figures, the improved version, accepted by Eur. Phys. J.
Nucleon Charge and Magnetization Densities from Sachs Form Factors
Relativistic prescriptions relating Sachs form factors to nucleon charge and
magnetization densities are used to fit recent data for both the proton and the
neutron. The analysis uses expansions in complete radial bases to minimize
model dependence and to estimate the uncertainties in radial densities due to
limitation of the range of momentum transfer. We find that the charge
distribution for the proton is significantly broad than its magnetization
density and that the magnetization density is slightly broader for the neutron
than the proton. The neutron charge form factor is consistent with the Galster
parametrization over the available range of Q^2, but relativistic inversion
produces a softer radial density. Discrete ambiguities in the inversion method
are analyzed in detail. The method of Mitra and Kumari ensures compatibility
with pQCD and is most useful for extrapolating form factors to large Q^2.Comment: To appear in Phys. Rev. C. Two new figures and accompanying text have
been added and several discussions have been clarified with no significant
changes to the conclusions. Now contains 47 pages including 21 figures and 2
table
High non-photonic electron production in + collisions at = 200 GeV
We present the measurement of non-photonic electron production at high
transverse momentum ( 2.5 GeV/) in + collisions at
= 200 GeV using data recorded during 2005 and 2008 by the STAR
experiment at the Relativistic Heavy Ion Collider (RHIC). The measured
cross-sections from the two runs are consistent with each other despite a large
difference in photonic background levels due to different detector
configurations. We compare the measured non-photonic electron cross-sections
with previously published RHIC data and pQCD calculations. Using the relative
contributions of B and D mesons to non-photonic electrons, we determine the
integrated cross sections of electrons () at 3 GeV/10 GeV/ from bottom and charm meson decays to be = 4.0({\rm
stat.})({\rm syst.}) nb and =
6.2({\rm stat.})({\rm syst.}) nb, respectively.Comment: 17 pages, 17 figure
Evolution of the differential transverse momentum correlation function with centrality in Au+Au collisions at GeV
We present first measurements of the evolution of the differential transverse
momentum correlation function, {\it C}, with collision centrality in Au+Au
interactions at GeV. {\it C} exhibits a strong dependence
on collision centrality that is qualitatively similar to that of number
correlations previously reported. We use the observed longitudinal broadening
of the near-side peak of {\it C} with increasing centrality to estimate the
ratio of the shear viscosity to entropy density, , of the matter formed
in central Au+Au interactions. We obtain an upper limit estimate of
that suggests that the produced medium has a small viscosity per unit entropy.Comment: 7 pages, 4 figures, STAR paper published in Phys. Lett.
Single Spin Asymmetry in Polarized Proton-Proton Elastic Scattering at GeV
We report a high precision measurement of the transverse single spin
asymmetry at the center of mass energy GeV in elastic
proton-proton scattering by the STAR experiment at RHIC. The was measured
in the four-momentum transfer squared range \GeVcSq, the region of a significant interference between the
electromagnetic and hadronic scattering amplitudes. The measured values of
and its -dependence are consistent with a vanishing hadronic spin-flip
amplitude, thus providing strong constraints on the ratio of the single
spin-flip to the non-flip amplitudes. Since the hadronic amplitude is dominated
by the Pomeron amplitude at this , we conclude that this measurement
addresses the question about the presence of a hadronic spin flip due to the
Pomeron exchange in polarized proton-proton elastic scattering.Comment: 12 pages, 6 figure
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