6,489 research outputs found
Entropy/Area spectra of the charged black hole from quasinormal modes
With the new physical interpretation of quasinormal modes proposed by
Maggiore, the quantum area spectra of black holes have been investigated
recently. Adopting the modified Hod's treatment, results show that the area
spectra for black holes are equally spaced and the spacings are in a unified
form, , in Einstein gravity. On the other hand,
following Kunstatter's method, the studies show that the area spectrum for a
nonrotating black hole with no charge is equidistant. And for a rotating (or
charged) black hole, it is also equidistant and independent of the angular
momentum (or charge ) when the black hole is far from the extremal case.
In this paper, we mainly deal with the area spectrum of the stringy charged
Garfinkle-Horowitz-Strominger black hole, originating from effective action
that emerges in the low-energy string theory. We find that both methods give
the same results-that the area spectrum is equally spaced and does not depend
on the charge . Our study may provide new insights into understanding the
area spectrum and entropy spectrum for stringy black holes.Comment: 13 pages, no figure
Stacking tunable interlayer magnetism in bilayer CrI3
Diverse interlayer tunability of physical properties of two-dimensional
layers mostly lies in the covalent-like quasi-bonding that is significant in
electronic structures but rather weak for energetics. Such characteristics
result in various stacking orders that are energetically comparable but may
significantly differ in terms of electronic structures, e.g. magnetism.
Inspired by several recent experiments showing interlayer
anti-ferromagnetically coupled CrI3 bilayers, we carried out first-principles
calculations for CrI3 bilayers. We found that the anti-ferromagnetic coupling
results from a new stacking order with the C2/m space group symmetry, rather
than the graphene-like one with R3 as previously believed. Moreover, we
demonstrated that the intra- and inter-layer couplings in CrI3 bilayer are
governed by two different mechanisms, namely ferromagnetic super-exchange and
direct-exchange interactions, which are largely decoupled because of their
significant difference in strength at the strong- and weak-interaction limits.
This allows the much weaker interlayer magnetic coupling to be more feasibly
tuned by stacking orders solely. Given the fact that interlayer magnetic
properties can be altered by changing crystal structure with different stacking
orders, our work opens a new paradigm for tuning interlayer magnetic properties
with the freedom of stacking order in two dimensional layered materials
Lorentz invariance violation in the neutrino sector: a joint analysis from big bang nucleosynthesis and the cosmic microwave background
We investigate constraints on Lorentz invariance violation in the neutrino
sector from a joint analysis of big bang nucleosynthesis and the cosmic
microwave background. The effect of Lorentz invariance violation during the
epoch of big bang nucleosynthesis changes the predicted helium-4 abundance,
which influences the power spectrum of the cosmic microwave background at the
recombination epoch. In combination with the latest measurement of the
primordial helium-4 abundance, the Planck 2015 data of the cosmic microwave
background anisotropies give a strong constraint on the deformation parameter
since adding the primordial helium measurement breaks the degeneracy between
the deformation parameter and the physical dark matter density.Comment: 10 pages, 8 figur
Epithelial-Mesenchymal Transition and its Regulation in Tumor Metastasis
Epithelial-mesenchymal transition (EMT) plays a key role in cancer metastasis. This process is a complex, multi-functional, and tightly regulated developmental program. EMT has been extensively investigated, but the molecular regulation of its signaling pathway is highly complex. In this study, the different elements of EMT cascades that could be targeted were determined. Difficulties in translating the preclinical findings in routine clinic were also distinguished. Future research will provide insights into the activation and regulation of various EMT programs in different tumor types and at distinct stages of tumor development. These results will likely facilitate the development of early detection strategies and improve the therapeutic targeting of malignant solid tumors
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