Double neutron star (DNS) merger events are promising candidates of short gamma-ray burst (sGRB) progenitors as well as high-frequency gravitational wave (GW) emitters. On August 17, 2017, such a ...coinciding event was detected by both the LIGO-Virgo gravitational wave detector network as GW170817 and Gamma-Ray Monitor on board NASA's Fermi Space Telescope as GRB 170817A. Here, we show that the fluence and spectral peak energy of this sGRB fall into the lower portion of the distributions of known sGRBs. Its peak isotropic luminosity is abnormally low. The estimated event rate density above this luminosity is at least Formula: see text Gpc
yr
, which is close to but still below the DNS merger event rate density. This event likely originates from a structured jet viewed from a large viewing angle. There are similar faint soft GRBs in the Fermi archival data, a small fraction of which might belong to this new population of nearby, low-luminosity sGRBs.
Guiding of relativistically intense laser pulses with peak power of 0.85 PW over 15 diffraction lengths was demonstrated by increasing the focusing strength of a capillary discharge waveguide using ...laser inverse bremsstrahlung heating. This allowed for the production of electron beams with quasimonoenergetic peaks up to 7.8 GeV, double the energy that was previously demonstrated. Charge was 5 pC at 7.8 GeV and up to 62 pC in 6 GeV peaks, and typical beam divergence was 0.2 mrad.
In this work, the electronic properties of phosphorene nanoribbons with different width and edge configurations are studied by using density functional theory. It is found that the armchair ...phosphorene nanoribbons are semiconducting while the zigzag nanoribbons are metallic. The band gaps of armchair nanoribbons decrease monotonically with increasing ribbon width. By passivating the edge phosphorus atoms with hydrogen, the zigzag series also become semiconducting, while the armchair series exhibit a larger band gap than their pristine counterpart. The electronic transport properties of these phosphorene nanoribbons are then investigated using Boltzmann theory and relaxation time approximation. We find that all the semiconducting nanoribbons exhibit very large values of Seebeck coefficient and can be further enhanced by hydrogen passivation at the edge. Taking pristine armchair nanoribbons and hydrogen-passivated zigzag naoribbons with width N = 7, 8, 9 as examples, we calculate the lattice thermal conductivity with the help of phonon Boltzmann transport equation and evaluate the width-dependent thermoelectric performance. Due to significantly enhanced Seebeck coefficient and decreased thermal conductivity, we find that at least one type of phosphorene nanoribbons can be optimized to exhibit very high figure of merit (ZT values) at room temperature, which suggests their appealing thermoelectric applications.
In Alzheimer's disease (AD), neurodegenerative signals such as amyloid-beta (Aβ) and the precursors of neurotrophins, outbalance neurotrophic signals, causing synaptic dysfunction and ...neurodegeneration. The neurotrophin receptor p75 (p75NTR) is a receptor of Aβ and mediates Aβ-induced neurodegenerative signals. The shedding of its ectodomain from the cell surface is physiologically regulated; however, the function of the diffusible p75NTR ectodomain (p75ECD) after shedding remains largely not known. Here, we show that p75ECD levels in cerebrospinal fluid and in the brains of Alzheimer's patients and amyloid-beta precursor protein (APP)/PS1 transgenic mice were significantly reduced, due to inhibition of the sheddase-tumor necrosis factor-alpha-converting enzyme by Aβ. Restoration of p75ECD to the normal level by brain delivery of the gene encoding human p75ECD before or after Aβ deposition in the brain of APP/PS1 mice reversed the behavioral deficits and AD-type pathologies, such as Aβ deposit, apoptotic events, neuroinflammation, Tau phosphorylation and loss of dendritic spine, neuronal structures and synaptic proteins. Furthermore, p75ECD can also reduce amyloidogenesis by suppressing β-secretase expression and activities. Our data demonstrate that p75ECD is a physiologically neuroprotective molecule against Aβ toxicity and would be a novel therapeutic target and biomarker for AD.
In this two‐part paper, a description is provided of a version of the AM4.0/LM4.0 atmosphere/land model that will serve as a base for a new set of climate and Earth system models (CM4 and ESM4) under ...development at NOAA's Geophysical Fluid Dynamics Laboratory (GFDL). This version, with roughly 100 km horizontal resolution and 33 levels in the vertical, contains an aerosol model that generates aerosol fields from emissions and a “light” chemistry mechanism designed to support the aerosol model but with prescribed ozone. In Part 1, the quality of the simulation in AMIP (Atmospheric Model Intercomparison Project) mode—with prescribed sea surface temperatures (SSTs) and sea‐ice distribution—is described and compared with previous GFDL models and with the CMIP5 archive of AMIP simulations. The model's Cess sensitivity (response in the top‐of‐atmosphere radiative flux to uniform warming of SSTs) and effective radiative forcing are also presented. In Part 2, the model formulation is described more fully and key sensitivities to aspects of the model formulation are discussed, along with the approach to model tuning.
Key Points
A description is provided of the AM4.0/LM4.0 model that will serve as a base for a new set of GFDL/NOAA climate and Earth system models
The simulation quality in AMIP mode is described and compared with previous GFDL models and with the CMIP5 archive of AMIP simulations
The model's Cess sensitivity and effective radiative forcing are presented
Growth of high-quality single-crystalline InSb layers remains challenging in material science. Such layered InSb materials are highly desired for searching for and manipulation of Majorana Fermions ...in solid state, a fundamental research task in physics today, and for development of novel high-speed nanoelectronic and infrared optoelectronic devices. Here, we report on a new route toward growth of single-crystalline, layered InSb materials. We demonstrate the successful growth of free-standing, two-dimensional InSb nanosheets on one-dimensional InAs nanowires by molecular-beam epitaxy. The grown InSb nanosheets are pure zinc-blende single crystals. The length and width of the InSb nanosheets are up to several micrometers and the thickness is down to ∼10 nm. The InSb nanosheets show a clear ambipolar behavior and a high electron mobility. Our work will open up new technology routes toward the development of InSb-based devices for applications in nanoelectronics, optoelectronics, and quantum electronics and for the study of fundamental physical phenomena.
Abstract
BL Lacertae is a key monitoring target of the 1.26 m National Astronomical Observatory–Guangzhou University Infrared/Optical telescope. Within the monitored duration from 2020 September 4 to ...2022 September 28, we report 13,948 observations at the
g
,
r
, and
i
bands (
g
band: 4498,
r
band: 4866,
i
band: 4584). (1) In the monitored duration, this source is located in a very bright and variable state. The maximum variabilities are Δ
m
g
= 2.013 ± 0.073 mag at
g
band, Δ
m
r
= 1.900 ± 0.049 mag at
r
band, and Δ
m
i
= 2.279 ± 0.089 mag at
i
band. (2) Among the
gri
intraday lightcurves, there are 104 portions of data sets displaying intraday variabilities (IDVs), with the IDV timescales (Δ
T
) being in the range of 15.84–375.84 minutes and the biggest variable value Δ
m
= 0.430 ± 0.041 mag. (3) The distributions of Δ
T
show frequency-dependent behavior, and with the frequency increasing, Δ
T
tend to be shorter. The variable rates (
V
=
Δ
m
Δ
T
) from the
g
band are more intense than the values (
V
r
) from the
r
band, but are more stable than the values (
V
i
) from the
i
band. (4) On three days (2020 September 7, 2020 September 19, and 2022 September 7), we find the intraday periodic oscillations, whose periods are around 150 minutes, 232 minutes, and 150 minutes, respectively, and which might come from the source “flickering.” (5) Based on the distributions between flux densities (
F
gri
) and spectral indices (
α
), they show the bluer-when-brighter behaviors and some uneven locations, which should come from the ministructures of the jet, the shock-induced particle acceleration, or magnetic reconnection in the jet.
Phosphorene has attracted tremendous interest recently due to its intriguing electronic properties. However, the thermal transport properties of phosphorene, especially for its allotropes, are still ...not well-understood. In this work, we calculate the thermal conductivities of five phosphorene allotropes (α-, β-, γ-, δ- and ζ-phase) by using phonon Boltzmann transport theory combined with first-principles calculations. It is found that the α-phosphorene exhibits considerable anisotropic thermal transport, while it is less obvious in the other four phosphorene allotropes. The highest thermal conductivity is found in the β-phosphorene, followed by the δ-, γ- and ζ-phase. The much lower thermal conductivity of the ζ-phase can be attributed to its relatively complex atomic configuration. It is expected that the rich thermal transport properties of phosphorene allotropes can have potential applications in the thermoelectrics and thermal management.
Summary
Background
Hepatitis C virus (HCV) infection has been linked to an increased risk of insulin resistance and carotid atherosclerosis.
Aim
To investigate the association between HCV infection ...and stroke, and the effect of interferon‐based therapy (IBT) on stroke risk in chronic hepatitis C (CHC) patients.
Methods
We conducted a retrospective cohort study that followed up 3113 subjects with a newly detected HCV infection and 12 452 age‐ and gender‐matched subjects without HCV infection selected from a random sample of 106 beneficiaries from the Taiwan National Health Insurance Program up to 5 years. Use of IBT was defined as treatment with interferon alpha, pegylated interferon alpha‐2a or pegylated interferon alpha‐2b for at least 3 months. The hazard ratio (HR) for newly detected stroke was calculated for subjects with HCV compared to those without HCV, and for IBT‐treated HCV patients compared to non‐IBT‐treated HCV patients while adjusting for possible confounding factors.
Results
The overall person‐years of follow‐up were 8624.11 in patients with HCV, 54 533.69 in patients without HCV, 666.65 in IBT‐treated patients, and 7886.49 in nontreated patients. The multivariable‐adjusted hazard ratio (HR) for newly detected stroke was 1.23 for subjects with HCV compared to the age‐ and sex‐matched subjects without HCV (adjusted HR = 1.23, 95% CI = 1.06–1.42, P = 0.008). Moreover, use of IBT significantly reduced the risk of stroke in HCV patients (adjusted HR = 0.39, 95% CI = 0.16–0.95, P = 0.039) after adjusting for known prognostic factors.
Conclusions
Interferon‐based therapy may reduce the long‐term risk of stroke in patients with chronic HCV infection.
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