335 research outputs found
Experimentally well-constrained masses of 27P and 27S: implications for studies of explosive binary systems
The mass of 27P is expected to impact the X-ray burst (XRB) model predictions of burst light curves and the composition of the burst ashes, but large uncertainties and inconsistencies still exist in the reported 27P masses. We have used the ß-decay spectroscopy of 27S to determine the most precise mass excess of 27P to date to be keV, which is 63 keV (2.3s) higher and a factor of 3 more precise than the value recommended in the 2016 Atomic Mass Evaluation. Based on the new 27P mass, the P reaction rate and its uncertainty were recalculated using Monte Carlo techniques. We also estimated the previously unknown mass excess of 27S to be 17678(77) keV, based on the measured ß-delayed two-proton energy and the Coulomb displacement energy relations. The impact of these well-constrained masses and reaction rates on the modeling of the explosive astrophysical scenarios has been investigated by post-processing XRB and hydrodynamic nova models. Compared to the model calculations based on the masses and rates from databases, the abundance of in the burst ashes is increased by a factor of 2.4, while no substantial change was found in the XRB energy generation rate or the light curve. Our calculation also suggests that 27S is not a significant waiting point in the rapid proton capture process, and the change of the P reaction rate is not sufficiently large to affect the conclusion previously drawn on the nova contribution to the synthesis of galactic 26Al.Postprint (published version
Hyperglycemia-induced inhibition of DJ-1 expression compromised the effectiveness of ischemic postconditioning cardioprotection in rats
published_or_final_versio
Covariant anomaly and Hawking radiation from the modified black hole in the rainbow gravity theory
Recently, Banerjee and Kulkarni (R. Banerjee, S. Kulkarni, arXiv:0707.2449
[hep-th]) suggested that it is conceptually clean and economical to use only
the covariant anomaly to derive Hawking radiation from a black hole. Based upon
this simplified formalism, we apply the covariant anomaly cancellation method
to investigate Hawking radiation from a modified Schwarzschild black hole in
the theory of rainbow gravity. Hawking temperature of the gravity's rainbow
black hole is derived from the energy-momentum flux by requiring it to cancel
the covariant gravitational anomaly at the horizon. We stress that this
temperature is exactly the same as that calculated by the method of cancelling
the consistent anomaly.Comment: 5 page
MEK1 drives oncogenic signaling and interacts with PARP1 for genomic and metabolic homeostasis in malignant pleural mesothelioma.
Malignant pleural mesothelioma (MPM) is a lethal malignancy etiologically caused by asbestos exposure, for which there are few effective treatment options. Although asbestos carcinogenesis is associated with reactive oxygen species (ROS), the bona fide oncogenic signaling pathways that regulate ROS homeostasis and bypass ROS-evoked apoptosis in MPM are poorly understood. In this study, we demonstrate that the mitogen-activated protein kinase (MAPK) pathway RAS-RAF-MEK-ERK is hyperactive and a molecular driver of MPM, independent of histological subtypes and genetic heterogeneity. Suppression of MAPK signaling by clinically approved MEK inhibitors (MEKi) elicits PARP1 to protect MPM cells from the cytotoxic effects of MAPK pathway blockage. Mechanistically, MEKi induces impairment of homologous recombination (HR) repair proficiency and mitochondrial metabolic activity, which is counterbalanced by pleiotropic PARP1. Consequently, the combination of MEK with PARP inhibitors enhances apoptotic cell death in vitro and in vivo that occurs through coordinated upregulation of cytotoxic ROS in MPM cells, suggesting a mechanism-based, readily translatable strategy to treat this daunting disease. Collectively, our studies uncover a previously unrecognized scenario that hyperactivation of the MAPK pathway is an essential feature of MPM and provide unprecedented evidence that MAPK signaling cooperates with PARP1 to homeostatically maintain ROS levels and escape ROS-mediated apoptosis
Intrasubband and Intersubband Electron Relaxation in Semiconductor Quantum Wire Structures
We calculate the intersubband and intrasubband many-body inelastic Coulomb
scattering rates due to electron-electron interaction in two-subband
semiconductor quantum wire structures. We analyze our relaxation rates in terms
of contributions from inter- and intrasubband charge-density excitations
separately. We show that the intersubband (intrasubband) charge-density
excitations are primarily responsible for intersubband (intrasubband) inelastic
scattering. We identify the contributions to the inelastic scattering rate
coming from the emission of the single-particle and the collective excitations
individually. We obtain the lifetime of hot electrons injected in each subband
as a function of the total charge density in the wire.Comment: Submitted to PRB. 20 pages, Latex file, and 7 postscript files with
Figure
Hawking Radiation of Black Holes in Infrared Modified Ho\v{r}ava-Lifshitz Gravity
We study the Hawking radiation of the spherically symmetric, asymptotically
flat black holes in the infrared modified Horava-Lifshitz gravity by applying
the methods of covariant anomaly cancellation and effective action, as well as
the approach of Damour-Ruffini-Sannan's. These black holes behave as the usual
Schwarzschild ones of the general relativity when the radial distance is very
large. We also extend the method of covariant anomaly cancellation to derive
the Hawking temperature of the spherically symmetric, asymptotically AdS black
holes that represent the analogues of the Schwarzschild AdS ones.Comment: no figures, 16 pages,accepted by EPJ
Inelastic lifetimes of confined two-component electron systems in semiconductor quantum wire and quantum well structures
We calculate Coulomb scattering lifetimes of electrons in two-subband quantum
wires and in double-layer quantum wells by obtaining the quasiparticle
self-energy within the framework of the random-phase approximation for the
dynamical dielectric function. We show that, in contrast to a single-subband
quantum wire, the scattering rate in a two-subband quantum wire contains
contributions from both particle-hole excitations and plasmon excitations. For
double-layer quantum well structures, we examine individual contributions to
the scattering rate from quasiparticle as well as acoustic and optical plasmon
excitations at different electron densities and layer separations. We find that
the acoustic plasmon contribution in the two-component electron system does not
introduce any qualitatively new correction to the low energy inelastic
lifetime, and, in particular, does not produce the linear energy dependence of
carrier scattering rate as observed in the normal state of high-
superconductors.Comment: 16 pages, RevTeX, 7 figures. Also available at
http://www-cmg.physics.umd.edu/~lzheng
Rotating metrics admitting non-perfect fluids in General Relativity
In this paper, by applying Newman-Janis algorithm in spherical symmetric
metrics, a class of embedded rotating solutions of field equations is
presented. These solutions admit non-perfect fluidsComment: LaTex, 39 page
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.
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