The jet breaks in the afterglow light curves of short gamma-ray bursts (SGRBs), rarely detected so far, are crucial for estimating the half-opening angles of the ejecta (θj) and hence the neutron ...star merger rate. In this work, we report the detection of jet decline behaviors in GRB 150424A and GRB 160821B, and find θj ∼ 0.1 rad. Together with five events reported before 2015 and three others "identified" recently (GRB 050709, GRB 060614, and GRB 140903A), we have a sample consisting of nine SGRBs and one long-short GRB with reasonably estimated θj. In particular, three Swift bursts in the sample have redshifts z ≤ 0.2, with which we estimate the local neutron star merger rate density to be or if the narrowly beamed GRB 061201 is excluded. Inspired by the typical θj ∼ 0.1 rad found currently, we further investigate whether the off-beam GRBs (in the uniform jet model) or the off-axis events (in the structured jet model) can significantly enhance the GRB/GW association. For the former, the enhancement is at most moderate, while for the latter the enhancement can be much greater and a high GRB/GW association probability of ∼10% is possible. We also show that the data of GRB 160821B may contain a macronova/kilonova emission component with a temperature of ∼3100 K at ∼3.6 days after the burst and more data are needed to ultimately clarify.
In ultrahigh-dimensional data analysis, it is extremely challenging to identify important interaction effects, and a top concern in practice is computational feasibility. For a dataset with n ...observations and p predictors, the augmented design matrix including all linear and order-2 terms is of size n × (p ² + 3 p)/2. When p is large, say more than tens of hundreds, the number of interactions is enormous and beyond the capacity of standard machines and software tools for storage and analysis. In theory, the interaction-selection consistency is hard to achieve in high-dimensional settings. Interaction effects have heavier tails and more complex covariance structures than main effects in a random design, making theoretical analysis difficult. In this article, we propose to tackle these issues by forward-selection-based procedures called iFOR, which identify interaction effects in a greedy forward fashion while maintaining the natural hierarchical model structure. Two algorithms, iFORT and iFORM, are studied. Computationally, the iFOR procedures are designed to be simple and fast to implement. No complex optimization tools are needed, since only OLS-type calculations are involved; the iFOR algorithms avoid storing and manipulating the whole augmented matrix, so the memory and CPU requirement is minimal; the computational complexity is linear in p for sparse models, hence feasible for p ≫ n . Theoretically, we prove that they possess sure screening property for ultrahigh-dimensional settings. Numerical examples are used to demonstrate their finite sample performance. Supplementary materials for this article are available online.
Developing highly efficient, low-cost, and multifunctional electro-catalysts to replace noble metals is of significant importance for energy storage and conversion systems. Herein, we demonstrate a ...facile strategy for the preparation of CoP quantum dots (QDs) embedded in S,N-codoped graphite carbon (CoP@SNC) by using organophosphoric acid as both phosphorus and carbon sources. Benefiting from the strong coupling and synergistic effect between CoP QDs and highly conductive S,N-codoped carbon, well-structured porosity and high specific surface area, the resulting CoP@SNC exhibits excellent activities for oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and oxygen reduction reaction (ORR), making it a trifunctional electro-catalyst for overall water splitting and rechargeable Zn-air batteries. When CoP@SNC is used for overall water splitting, a cell voltage as low as 1.64 V is required to reach the current density of 10 mA cm-2; the obtained rechargeable Zn-air battery with CoP@SNC as the air cathode exhibits a high open-circuit voltage of 1.45 V, a very low discharge-charge voltage gap (0.83 V at 10 mA cm-2), and a long cycle life (up to 180 cycles). This work not only offers a new strategy for the synthesis of CoP@SNC but also presents its huge potential as a trifunctional electro-catalyst for clean energy systems.
Abstract Gamma-ray bursts (GRBs) have been proposed as one of the promising sources of ultra-high-energy cosmic rays (UHECRs), but observational evidence is still lacking. The nearby brightest of all ...time GRB 221009A, a once in 1000 yr event, is able to accelerate protons to ∼10 3 EeV, and then generate extremly energetic neutrons via the photomeson production interaction. Protons arriving at the Milky Way are dominated by neutron-decay-induced protons. The intergalactic magnetic fields would not yield a sizable delay of the ≥10 EeV cosmic rays if its strength is ≲10 −13 G, while Galactic magnetic fields would cause a significant time delay. We predict that a UHECR burst from GRB 221009A would be detectable by the Pierre Auger Observatory and the TA×4, within ∼10 yr. The detection of such a UHECR outburst will provide the direct evidence for UHECR acceleration in GRBs.
Although the Trans-Himalayan region (THR) is an important endemic and rendezvous area of peste des petits ruminants (PPR), monitoring and prevention measurements are difficult to execute because of ...the rough geographical conditions. Besides, a heterogeneous breeding system and the poor veterinary service of susceptible animals compound the existing problems. Here, we propose a forecasting system to define the key points of PPR prevention and aid the countries in saving time, labor, and products to achieve the goal of the global eradication project of PPR. The spatial distribution of PPR was predicted in the THR for the first time using a niche model that was constructed with a combination of eco-geographical, anthropoid, meteorological, and host variables. The transboundary least-cost paths (LCPs) of small ruminants in the THR were also calculated. Our results reveal that the low-elevation area of the THR had a higher PPR risk and was mainly dominated by human variables. The high-elevation area had lower risk and was mainly dominated by natural variables. Eight LCPs representing corridors among India, Nepal, Bhutan, Bangladesh, and China were obtained. This confirmed the potential risk of transboundary communication by relying on PPR contamination on the grasslands for the first time. The predicted potential risk communication between the two livestock systems and landscapes (high and low elevation) might play a role in driving PPR transboundary transmission.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract The problem of missing Galactic supernova remnants (SNRs) refers to the issue that the currently known Galactic SNRs are significantly incomplete compared to the theoretical prediction. To ...expand the sample of Galactic SNRs, we use GLEAM and THOR+VGPS data across four wave bands ranging from 118 to 1420 MHz to drive a spectral index map covering the region within 26.°6 < l < 30.°6, ∣ b ∣ ≤ 1.°25, where numerous SNR candidates were recently found. By using the spectral index map of the sky region and detailed analysis of the spectral indices of individual sources, we confirmed four SNR candidates, namely G26.75+0.73, G27.06+0.04, G28.36+0.21, and G28.78−0.44, as SNRs. Additionally, we discovered an expanding molecular superbubble located in this region, discussed pulsars associated with SNR candidates, and discovered a long H α filament that spatially overlaps with the candidate G29.38+0.10. We suggest that the problem of missing Galactic SNRs not only arises from observation limitations, but also could be due to the low-density environments of some SNRs, and the different supernova explosion properties.
The development of energy selective, photon counting X-ray detectors allows for a wide range of new possibilities in the area of computed tomographic image formation. Under the assumption of perfect ...energy resolution, here we propose a tensor-based iterative algorithm that simultaneously reconstructs the X-ray attenuation distribution for each energy. We use a multilinear image model rather than a more standard stacked vector representation in order to develop novel tensor-based regularizers. In particular, we model the multispectral unknown as a three-way tensor where the first two dimensions are space and the third dimension is energy. This approach allows for the design of tensor nuclear norm regularizers, which like its 2D counterpart, is a convex function of the multispectral unknown. The solution to the resulting convex optimization problem is obtained using an alternating direction method of multipliers approach. Simulation results show that the generalized tensor nuclear norm can be used as a standalone regularization technique for the energy selective (spectral) computed tomography problem and when combined with total variation regularization it enhances the regularization capabilities especially at low energy images where the effects of noise are most prominent.
The origin of the IceCube neutrinos is still an open question. Upper limits from diffuse gamma-ray observations suggest that the neutrino sources are either distant or hidden from gamma-ray ...observations. It is possible that the neutrinos are produced in jets that are formed in core-collapsing massive stars and fail to break out, the so-called choked jets. We study neutrinos from the jets choked in the hydrogen envelopes of red supergiant stars. Fast photo-meson cooling softens the neutrino spectrum, making it hard to explain the PeV neutrinos observed by IceCube in a one-component scenario, but a two-component model can explain the spectrum. Furthermore, we predict that a newly born jet-driven type-II supernova may be observed to be associated with a neutrino burst detected by IceCube.
Gastric cancer is one of the most common cancers and has the highest mortality rate worldwide. It is worthwhile to explore the mechanism of gastric cancer progression. An increasing number of studies ...have found that non-coding RNAs including miRNA and lncRNA play important roles in gastric cancer progression. This review summarized the role of ectopic miRNA in gastric cancer proliferation, growth, migration, invasion and apoptosis. Meantime, aberrantly expressed miRNA also received a great deal of attention as potential biomarker for gastric cancer diagnosis and therapy. Over the last decade, lncRNA was considered to regulate gastric cancer progression at the transcript and post-transcript level. At the transcript level, lncRNA induced gastric cancer progression by changing chromatin modification and mRNA stabilization to regulate mRNA and miRNA expression. Furthermore, lncRNA regulated gastric cancer progression by completely combining with miRNA to produce ceRNA or promote protein stabilization at the post-transcript level. Greater attention of miRNA and lncRNA in gastric cancer can provide new insight of mechanism of cancer development and may be acted as a new anticancer target.
Macrophages are widely distributed innate immune cells that play indispensable roles in the innate and adaptive immune response to pathogens and in-tissue homeostasis. Macrophages can be activated by ...a variety of stimuli and polarized to functionally different phenotypes. Two distinct subsets of macrophages have been proposed, including classically activated (M1) and alternatively activated (M2) macrophages. M1 macrophages express a series of proinflammatory cytokines, chemokines, and effector molecules, such as IL-12, IL-23, TNF-α, iNOS and MHCI/II. In contrast, M2 macrophages express a wide array of anti-inflammatory molecules, such as IL-10, TGF-β, and arginase1. In most tumors, the infiltrated macrophages are considered to be of the M2 phenotype, which provides an immunosuppressive microenvironment for tumor growth. Furthermore, tumor-associated macrophages secrete many cytokines, chemokines, and proteases, which promote tumor angiogenesis, growth, metastasis, and immunosuppression. Recently, it was also found that tumor-associated macrophages interact with cancer stem cells. This interaction leads to tumorigenesis, metastasis, and drug resistance. So mediating macrophage to resist tumors is considered to be potential therapy.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
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