4,824 research outputs found
Gravitational-wave Emission from a Primordial Black Hole Inspiraling inside a Compact Star: a Novel Probe for Dense Matter Equation of State
Primordial black holes of planetary masses captured by compact stars are
widely studied to constrain their composition fraction of dark matter. Such a
capture may lead to an inspiral process and be detected through gravitational
wave signals. In this Letter, we study the post-capture inspiral process by
considering two different kinds of compact stars, i.e., strange stars and
neutron stars. The dynamical equations are numerically solved and the
gravitational wave emission is calculated. It is found that the Advanced LIGO
can detect the inspiraling of a solar mass primordial black hole at a
distance of 10 kpc, while a Jovian-mass case can even be detected at
megaparsecs. Promisingly, the next generation gravitational wave detectors can
detect the cases of solar mass primordial black holes up to
Mpc, and can detect Jovian-mass cases at several hundred megaparsecs. Moreover,
the kilohertz gravitational wave signal shows significant differences for
strange stars and neutron stars, potentially making it a novel probe to the
dense matter equation of state.Comment: 7 figures, 15 pages, match the accepted version, accepted by ApJ
Status epilepticus alters hippocampal PKAβ and PKAγ expression in mice
AbstractObjectivesTo investigate the localization and progressive changes of cyclic-AMP dependent protein kinase (cPKA) in the mouse hippocampus at acute stages during and after pilocarpine induced status epilepticus.MethodsPilocarpine induced status epilepticus mice were sacrificed 30min, 2h or 1 day after the start of a ∼7h lasting status as assessed by video-electroencephalography. Brains were processed for quantitative immunohistochemistry of hippocampal cPKAβ and cPKAγ, and immunohistochemical co-localization of cPKAβ and cPKAγ with calbindin (CB), calretinin (CR), and parvalbumin (PV).ResultsBased on anatomical and morphological assessment, cPKAβ was primarily expressed by principal cells and cPKAγ by interneurons. In CA1, cPKAβ co-localized with 76% of CB, 41% of CR, and 95% of PV-immunopositive cells, while cPKAγ co-localized with 50% of CB, 29% of CR, and 80% of PV-immunopositive cells. Upon induction of status epilepticus, cPKAβ expression was transiently reduced in CA1, whereas cPKAγ expression was sustainably reduced.ConclusioncPKA may play an important role in neuronal hyperexcitability, death and epileptogenesis during and after pilocarpine induced status epilepticus
Management of intractable epistaxis in patients who received radiation therapy for nasopharyngeal carcinoma
To report clinical manifestations, bleeding point localization, and outcomes of management in 16 patients with 16 instances of intractable epistaxis after radiation therapy for nasopharyngeal carcinoma. Retrospective chart review of 16 patients with nasopharyngeal carcinoma (mean age 52.06 ± 14.37 years) with 16 instances of intractable epistaxis during the past 5 years, whose diagnosis was confirmed by angiography (n = 10) or MRI/CT imaging studies and clinical manifestations (n = 6). The mean radiation dose to the affected carotid artery was 101.37 ± 34.85 Gy. Bleeding points were detected in the internal carotid artery (n = 8) or external carotid artery (n = 8). Detachable balloons were used in one affected artery for vascular occlusion; six were treated using an absorbable gelatin sponge (n = 4) or microcoils (diameter 1 mm) (n = 2). Endovascular embolization was successful in seven radiation carotid blowout syndromes with cessation of hemorrhage. One patient underwent external carotid artery ligation and one patient recovered without treatment. The clinical follow-up was 3 months. Therapeutic endovascular embolization of intractable epistaxis is both efficient and safe. It should be considered as the primary treatment modality in intractable epistaxis of nasopharyngeal carcinoma
Disorder in interacting quasi-one-dimensional systems: flat and dispersive bands
We investigate the superconductor-insulator transition (SIT) in disordered
quasi-one dimensional systems using the density-matrix renormalization group
method. Focusing on the case of an interacting spinful Hamiltonian at
quarter-filling, we contrast the differences arising in the SIT when the parent
non-interacting model features either flat or dispersive bands. Furthermore, by
comparing disorder distributions that preserve or not SU(2)-symmetry, we unveil
the critical disorder amplitude that triggers insulating behavior. While
scaling analysis suggests the transition to be of a
Berezinskii-Kosterlitz-Thouless type for all models (two lattices and two
disorder types), only in the flat-band model with Zeeman-like disorder the
critical disorder is nonvanishing. In this sense, the flat-band structure does
strengthen superconductivity. For both flat and dispersive band models, i) in
the presence of SU(2)-symmetric random chemical potentials, the
disorder-induced transition is from superconductor to insulator of singlet
pairs; ii) for the Zeeman-type disorder, the transition is from superconductor
to insulator of unpaired fermions. In all cases, our numerical results suggest
no intermediate disorder-driven metallic phase.Comment: 10 pages, 13 figure
Enhanced superconductivity and various edge modes in modulated - chains
We numerically investigate the ground state of the extended -
Hamiltonian with periodic local modulations in one dimension by using the
density-matrix renormalization group method. Examining charge and spin
excitation gaps, as well as the pair binding energy, with extrapolated results
to the thermodynamic limit, we obtain a rich ground-state phase diagram
consisting of the metallic state, the superconducting state, the phase
separation, and insulating states at commensurate fillings. Compared to the
homogeneous 1D - model, the superconductivity is greatly enhanced and
stabilized by the flat-band structure. This superconducting state in
quasi-periodic chains shares similar properties with ladder systems:
significant negative pair binding energy occurs, and the singlet pairing
correlation function dominates with the algebraic decay while the
single-particle Green's function and spin correlation function decay
exponentially. On the other hand, quasi-periodicity leads to nontrivial
topological nature in insulating states, characterized by different integer
Chern numbers at different fillings. Due to the interplay among the topology,
the interaction, and the 1D confinement, gapless edge modes show strong
spin-charge separation and in different regions can relate to different
collective modes, which are the charge of a single fermion, the magnon, and the
singlet-pair. We also find two interaction driven topological transitions: i)
at particle filling , the low-energy edge excitations change from the
magnon to singlet-pair, accompanied with pair formation in bulk; and ii) at
, while the gapless edge mode remains the charge of a single fermion,
there is a gap-closing point and a -phase shift in the quasi-particle
spectrum.Comment: 10 pages,15 figure
Sensorless Control of Permanent Magnet Synchronous Motors and EKF Parameter Tuning Research
This paper concerns the parameter tuning and the estimated results postprocessing of the extended Kalman filter for the sensorless control application of permanent magnet synchronous motors. At first an extended Kalman filter parameter tuning method is proposed based on the theoretical and simulation analysis of extended Kalman filter parameters. Furthermore, a sensorless control system is proposed based on the parameter tuning method and the simulation analysis of extended Kalman filter estimation results in different reference speeds and different load torques. The proposed sensorless control system consists of two parts. The first one is a module to self-regulate extended Kalman filter parameters. The second part can correct the estimated speed and the estimated rotation angle based on the reference speed and the electromagnetic torque. Finally, simulation results are presented to verify the feasibility and validity of the proposed sensorless control system
Gluon Condensation Signature in the GeV Gamma-Ray Spectra of Pulsars
The accumulation of gluons inside nucleons, i.e., the gluon condensation, may
lead to a characteristic broken power-law gamma-ray spectrum in high-energy
nucleon collisions. Here we show that the observed spectra of at least 25
sources in the second Fermi Large Area Telescope Catalog of Gamma-ray Pulsars
can be well fitted by such a broken power-law function that has only four free
parameters. It strongly indicates that the gamma-ray emission from these
pulsars is of hadronic origin, but with gluon condensation inside hadrons. It
is well known that the quark-gluon distribution in a free nucleon is different
from that in a bound nucleon. This work exposes the nuclear -dependence of
the gluon condensation effect, where refers to the baryon number. Our study
reveals the gluon condensation under the condition of , which may
open a new window for eavesdropping on the structure of compact stars on the
sub-nuclear level.Comment: 12 pages (9 pages for main text), 5 figures, 1 table, accepted by PRD
at
https://journals.aps.org/prd/accepted/fd07cQ89M2118d20490d0d014fdd00616d4cdeb8
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