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Abstract Background The inflammatory microenvironment plays an essential role in bone healing after fracture. The signaling lymphocytic activation molecule family (SLAMF) members deeply participate in inflammatory response and make a vast difference. Methods We identified SLAMF8 in GEO datasets (GSE129165 and GSE176086) and co-expression analyses were performed to define the relationships between SLAMF8 and osteogenesis relative genes (RUNX2 and COL1A1). In vitro, we established SLAMF8 knockdown and overexpression mouse bone marrow mesenchymal stem cells (mBMSCs) lines. qPCR, Western blot, ALP staining, ARS staining, Oil Red O staining and Immunofluorescence analyses were performed to investigate the effect of SLAMF8 in mBMSCs osteogenesis and adipogenesis. In vivo, mice femoral fracture model was performed to explore the function of SLAMF8. Results SLAMF8 knockdown significantly suppressed the expression of osteogenesis relative genes (RUNX2, SP7 and COL1A1), ALP activity and mineral deposition, but increased the expression of adipogenesis relative genes (PPARγ and C/EBPα). Additionally, SLAMF8 overexpression had the opposite effects. The role SLAMF8 played in mBMSCs osteogenic and adipogenic differentiation were through S100A6 and Wnt/β-Catenin signaling pathway. Moreover, SLAMF8 overexpression mBMSCs promoted the healing of femoral fracture. Conclusions SLAMF8 promotes osteogenesis and inhibits adipogenesis of mBMSCs via S100A6 and Wnt/β-Catenin signaling pathway. SLAMF8 overexpression mBMSCs effectively accelerate the healing of femoral fracture in mice.

We report our counterpart identification study for two high-energy neutrino events IC-130127A and IC-131204A listed in the IceCube Event Catalog of Alert Tracks. These two events belong to Gold alerts, which have a significant probability of being of astrophysical origin. Within the events’ 90% positional uncertainty regions, we, respectively, find PKS 2332–017 and PMN J1916–1519. The first source is a flat-spectrum radio quasar at redshift z = 1.18, and the second is a blazar of an uncertain type with photometric z = 0.968. As they correspondingly had a γ -ray flare temporally coincident with the arrival times of IC-130127A and IC-131204A, we identify them as the respective neutrino emitters. Detailed analysis of the γ -ray data for the two blazars, obtained with the Large Area Telescope onboard the Fermi Gamma-ray Space Telescope, is conducted. The two flares, respectively, from PKS 2332–017 and PMN J1916–1519 lasted ~4 yr and ~4 months and showed possible emission hardening by containing high-energy ~2–10 GeV photons in the emissions. Accompanying the flare of PKS 2332–017, optical and mid-infrared brightening variations were also observed. We discuss the properties of the two sources and compare the properties with those of the previously reported (candidate) neutrino-emitting blazars.

[Objective] Conventional positioning stiffness of rail transit vehicle bogies results in significant lateral forces between wheels and rails, leading to substantial wear and reduced operational efficiency when navigating curves with small to medium radii. To enhance the operational stability and curve negotiation performance of rail transit vehicles, an active radial system for bogies is proposed. [Method] The active radial system and the control principles are introduced. The software and hardware design process of the radial controller is outlined. A vehicle dynamics model is established, integrating with other system components. The functionality and performance of the radial controller are verified through semi-physical simulation experiments and circular track tests. [Result & Conclusion] Whether adopting a guided active detection mode or a precise beacon detection mode, the radial controller can effectively detect curve segments, aligning the bogie wheelsets toward radial positions during curve negotiation in accordance with the actual track information. When entering or exiting curves, the radial controller can drive the radial actuator to act immediately or in advance, effectively reducing the lag time. Simulation and circular track test results demonstrate that trains equipped with bogies featuring the active radial system exhibit a consistent and significantly lower variation in wheel-rail lateral force compared to conventional passive curve negotiation states. The performance of the guiding wheelsets is particularly outstanding. The proposed active radial controller improves the curve negotiation performance of trains and reduces wheel-rail wear.

The reasonable and efficient prediction of dam failure events is of great significance to the emergency rescue operations and the reduction in dam failure losses. This work presents a model that is based on the physical mechanism. It is coupled with a multi-architecture (multi-CPU and GPU) open-source two-dimensional flood model, which is based on high-precision terrain and land use data. The aim is to enhance the accuracy of dam break flood process simulations. The model uses DEM data as a computational grid and updates it at each time step to reflect breach evolution. Simultaneously, the breach evolution model incorporates an analysis of stress on sediment particles, establishing the initial erosion state and lateral expansion model while accounting for seepage. The determination of the overflow of the breach is resolved through the application of a two-dimensional hydrodynamic model. This approach achieves a robust connection between the upstream reservoir, the dam structure, and the downstream inundation area. The coupled model is utilized to calculate the failure of earth-rock dams and landslide dams, and a sensitivity analysis is conducted. Taum Sauk Dam and Tangjiashan landslide dam were selected to represent earth dam break and barrier lake break, respectively, which are the main types of dam breaks. The obtained results demonstrate strong concurrence with the measured data, the relative errors of the four important parameters of the application case, the peak discharge of the breach, the top width of the final breach, the depth of the breach and the arrival time of the maximum peak discharge are all within ±10%. Although the relative error of the completion time of the final breach is greater than 10%, it is about 30% less than the relative error of the physical model.

For a simple graph $ G = (V(G), E(G)) $, the Graovac-Pisanski index of $ G $ is defined as $ GP(G) = \frac{|V(G)|}{2|{\rm{Aut}}(G)|}\sum\limits_{u\in V(G)}\sum\limits_{\alpha\in {\rm{Aut}}(G)}d_G(u,\alpha(u)), $ where $ {\rm{Aut}}(G) $ is the automorphism group of $ G $ and $ d_G(u, v) $ is the length of a shortest path between the two vertices $ u $ and $ v $ in $ G $. Obviously, $ GP(G) = 0 $ if $ G $ has no nontrivial automorphisms. Let $ B_{n}^{3, 3} $ be the graph consisting of two disjoint 3-cycles with a path of length $ n-5 $ joining them. In this article, we prove that among all those $ n $-vertex bicyclic graphs in which every edge lies on at most one cycle, $ B_{n}^{3, 3} $ has the maximum Graovac-Pisanski index.

We report our study of the field of the ≃0.2 PeV neutrino event IC-190619A. This neutrino belongs to Gold events, which more likely have an astrophysical origin. Among the two γ -ray sources within the neutrino’s positional uncertainty region, we find that one of them, the BL Lac–type blazar PKS 2254+074, had a γ -ray flare at the arrival time of the neutrino. The flare is determined to have lasted ∼2.5 yr in a 180 day binned light curve, constructed from the data collected with the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. Accompanying the flare, optical and mid-infrared brightening is also seen. In addition, ≥10 GeV high-energy photons from the source have been detected, suggesting a hardening of the emission during the flare. Given both the positional and temporal coincidence of PKS 2254+074 with IC-190619A, we suggest that this blazar is likely another member of a few recently identified (candidate) neutrino-emitting blazars.

This paper is concerned with the following quasilinear Schrödinger equations of the form: \begin{equation*} -\Delta u-u\Delta (u^2)+u=|u|^{p-2}u, \qquad x\in \mathbb{R}^3, \end{equation*} where $p\in\left(2,12\right)$. By making use of the constrained minimization method on a special manifold, we prove that the existence of positive radial solutions of the above problem for any $p\in(2,12)$.

Abstract Background The available therapeutic options for large bone defects remain extremely limited, requiring new strategies to accelerate bone healing. Genetically modified bone mesenchymal stem cells (BMSCs) with enhanced osteogenic capacity are recognised as one of the most promising treatments for bone defects. Methods We performed differential expression analysis of miRNAs between human BMSCs (hBMSCs) and human dental pulp stem cells (hDPSCs) to identify osteogenic differentiation-related microRNAs (miRNAs). Furthermore, we identified shared osteogenic differentiation-related miRNAs and constructed an miRNA-transcription network. The Forkhead box protein A1 (FOXA1) knockdown strategy with a lentiviral vector was used to explore the role of FOXA1 in the osteogenic differentiation of MSCs. Cell Counting Kit-8 was used to determine the effect of the knockdown of FOXA1 on hBMSC proliferation; real-time quantitative reverse transcription PCR (qRT-PCR) and western blotting were used to investigate target genes and proteins; and alkaline phosphatase (ALP) staining and Alizarin Red staining (ARS) were used to assess ALP activity and mineral deposition, respectively. Finally, a mouse model of femoral defects was established in vivo, and histological evaluation and radiographic analysis were performed to verify the therapeutic effects of FOXA1 knockdown on bone healing. Results We identified 22 shared and differentially expressed miRNAs between hDPSC and hBMSC, 19 of which were downregulated in osteogenically induced samples. The miRNA-transcription factor interaction network showed that FOXA1 is the most significant and novel osteogenic differentiation biomarker among more than 300 transcription factors that is directly targeted by 12 miRNAs. FOXA1 knockdown significantly promoted hBMSC osteo-specific genes and increased mineral deposits in vitro. In addition, p-ERK1/2 levels were upregulated by FOXA1 silencing. Moreover, the increased osteogenic differentiation of FOXA1 knockdown hBMSCs was partially rescued by the addition of ERK1/2 signalling inhibitors. In a mouse model of femoral defects, a sheet of FOXA1-silencing BMSCs improved bone healing, as detected by microcomputed tomography and histological evaluation. Conclusion These findings collectively demonstrate that FOXA1 silencing promotes the osteogenic differentiation of BMSCs via the ERK1/2 signalling pathway, and silencing FOXA1 in vivo effectively promotes bone healing, suggesting that FOXA1 may be a novel target for bone healing.

Abstract Background Aucubin (AU), an iridoid glucoside isolated from many traditional herbal medicines, has anti-osteoporosis and anti-apoptosis bioactivities. However, the effect of AU on the treatment of bone-fracture remains unknown. In the present study, the aims were to investigate the roles and mechanisms of AU not only on osteoblastogenesis of human bone marrow-derived mesenchymal stromal cells (hBM-MSCs) and anti-oxidative stress injury in vitro, but also on bone-fracture regeneration by a rat tibial fracture model in vivo. Methods CCK-8 assay was used to assess the effect of AU on the viability and proliferation of hBM-MSCs. The expression of specific genes and proteins on osteogenesis, apoptosis and signaling pathways was measured by qRT-PCR, western blotting and immunofluorescence analysis. ALP staining and quantitative analysis were performed to evaluate ALP activity. ARS and quantitative analysis were performed to evaluate calcium deposition. DCFH-DA staining was used to assess the level of reactive oxygen species (ROS). A rat tibial fracture model was established to validate the therapeutic effect of AU in vivo. Micro-CT with quantitative analysis and histological evaluation were used to assess the therapeutic effect of AU locally injection at the fracture site. Results Our results revealed that AU did not affect the viability and proliferation of hBM-MSCs. Compared with control group, western blotting, PCR, ALP activity and calcium deposition proved that AU-treated groups promoted osteogenesis of hBM-MSCs. The ratio of phospho-Smad1/5/9 to total Smad also significantly increased after treatment of AU. AU-induced expression of BMP2 signaling target genes BMP2 and p-Smad1/5/9 as well as of osteogenic markers COL1A1 and RUNX2 was downregulated after treating with noggin and LDN193189. Furthermore, AU promoted the translocation of Nrf2 from cytoplasm to nucleus and the expression level of HO1 and NQO1 after oxidative damage. In a rat tibial fracture model, local injection of AU promoted bone regeneration. Conclusions Our study demonstrates the dual effects of AU in not only promoting bone-fracture healing by regulating osteogenesis of hBM-MSCs partly via canonical BMP2/Smads signaling pathway but also suppressing oxidative stress damage partly via Nrf2/HO1 signaling pathway.

Intrigued by recent high-energy study results for nearby galaxies with γ -ray emission and in particular NGC 1068 that has been detected as a neutrino-emitting source by the IceCube Neutrino Observatory, we conduct a detailed analysis of the γ -ray data of the galaxies NGC 1068 and NGC 253, obtained with the Large Area Telescope on board the Fermi γ -ray Space Telescope. By checking their possible spectral features and then constructing light curves in the corresponding energy ranges, we identify spectral-change activity from NGC 1068 in the ≥2 GeV energy range and long-term, statistically significant changes for NGC 253 in the ≥5 GeV energy range. In the former, the emission appears harder in two half-year periods than in the otherwise “quiescent” state. In the latter, an ∼two-fold decrease in the detection significance after MJD = 57023 is clearly revealed by the test-statistic maps we obtain. Considering the previous studies carried out and the various models proposed for the γ -ray emissions of the two sources, we discuss the implications of our findings. We suspect that a jet (or outflow) in NGC 1068 might contribute to the γ -ray emission. The nature of the long-term statistically significant changes for NGC 253 is not clear, but since the part of the GeV emission may be connected to the very-high-energy (VHE) emission from the center of the galaxy, it could be further probed with VHE observations.

We search for possible pulsar TeV halos among the very-high-energy (VHE) sources reported in different VHE surveys, among which in particular we use the results from the first Large High Altitude Air Shower Observatory catalog of γ -ray sources. Six candidates are found. They share similar properties of containing a middle-aged, γ -ray–bright pulsar in their positional error circles (the respective pulsars are J0248+6021, J0359+5414, J0622+3749, J0633+0632, J2006+3102, and J2238+5903), being in a rather clean field without any common Galactic VHE-emitting supernova remnants or (bright) pulsar wind nebulae (PWNe), and showing an absence of any γ -ray emissions in 0.1–500 GeV after removing the pulsars’ emissions. Combining these candidates with several reported (candidate) TeV halos, we obtain relationships between their luminosity at 50 TeV ( L _50TeV ) and the corresponding pulsars’ spin-down energy ( $\dot{E}$ ), which are ${L}_{50\mathrm{TeV}}\sim {\dot{E}}^{0.9}$ and ${L}_{50\mathrm{TeV}}/\dot{E}\sim 6.4\times {10}^{-4}$ , respectively. The relationships are nearly identical to previously reported ones. We probe possible connections between the extent/sizes of the VHE sources and the pulsars’ ages, and find a weak older-and-smaller trend. By comparing to the VHE detection results for PWNe, it is clear that the (candidate) TeV halos have hard emissions by either having power-law indices smaller than 2 in 1–25 TeV or by only being detected in 25–100 TeV. In addition, we also consider seven other VHE sources as possible TeV halos based on the results from different studies of them, but they do not fit cleanly with the properties listed above, indicating their potentially complex nature.

We analyze more than 15 yr of γ -ray data obtained with the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope (Fermi) for the region of the young supernova remnant (SNR) RCW 103, since the nearby source 4FGL J1616.2−5054e, counterpart to HESS J1616−518 and ≃13′ away from the SNR, is determined to be extended in the more recent Fermi-LAT source catalog. Different templates for 4FGL J1616.2−5054e and RCW 103 are tested, and we find that a point source (PS) with a power-law (PL) spectrum at the southern limb of the SNR best describes the detected γ -ray emission. The photon index of the PL emission is Γ ≃ 2.31 (or α ≃ 2.4 in a log-parabola model), softer than the previously reported Γ ≃ 2.0 when the counterpart to HESS J1616−518 was considered to be a PS (which likely caused misidentification of extended emission at RCW 103). In order to produce the γ -ray emission in a hadronic scenario, we estimate that protons with an index ∼2.4 PL energy distribution are needed. These results fit with those from multiwavelength observations that have indicated the remnant at the southern limb is interacting with a molecular cloud.

This paper is concerned with the following modified Kirchhoff type problem $ \begin{align*} -\left(a+b\int_{\mathbb{R}^3}|\nabla u|^2\right)\Delta u-u\Delta (u^2)-\lambda u=|u|^{p-2}u, \; \; \; x\in \mathbb{R}^3, \end{align*} $ where $ a, b > 0 $ are constants and $ \lambda\in \mathbb R $. When $ p=\frac{16}{3} $, we prove that the existence of normalized solution with a prescribed $ L^2 $-norm for the above equation by applying constrained minimization method. Moreover, when $ p\in\left(\frac{10}{3}, \frac{16}{3}\right) $, we prove the existence of mountain pass type normalized solution for the above modified Kirchhoff equation by using the perturbation method. And the asymptotic behavior of normalized solution as $ b\rightarrow 0 $ is analyzed. These conclusions extend some known ones in previous papers.

This paper is concerned with the following fourth-order elliptic equation of the form: Δ2u−Δu−uΔ(u2)+u=|u|p−2u,x∈RN,where Δ2u≔Δ(Δu), 4≤N≤6and p∈2,2∗. By making use of the constrained minimization on a special manifold, we prove that the existence of nontrivial solutions of the above problem for any p∈2,2∗. Our result can be regarded as a partial extension of some related literature with 4

Using the γ -ray data obtained with the Large Area Telescope on board the Fermi Gamma-ray Space Telescope (Fermi) for ∼14 yr, we examine the high-energy emission emanating from the center of the Andromeda galaxy M31. Different from previously reported results, which show a seemingly extended source, we instead find two individual point sources, one consistent with being at the center and one 0.°4 southeast of the center. The emission of the former is well described using a log-parabola model, similar to those of previous studies, and that of the latter can be fitted with a power law. We discuss the possible origins for the two sources. M31's central source, now consistent with being a point source, necessitates a revisit of its previously discussed originations with this new property taken into consideration, in particular those cosmic rays or dark matter scenarios involving extended source distributions. The SE source appears to have a projected distance of ∼6 kpc from M31's center, and the investigation is required as to whether it is a source locally associated with M31, or is instead a background extragalactic one.

The paper focuses on the modified Kirchhoff equation \begin{align*} -\left(a+b\int_{\mathbb{R}^N}|\nabla u|^2dx\right)\Delta u-u\Delta (u^2)+V(x)u=\lambda f(u), \quad x\in \mathbb{R}^N, \end{align*} where $a,b>0$, $V(x)\in C(\mathbb{R}^N,\mathbb{R})$ and $\lambda

In recent years, with the continuous development of online geographic information services, the multiscale online expression of geographic elements and topological information has become a hot research topic. Currently, a large amount of research focuses mainly on the compression of vector line elements. The main shortcoming of current algorithms is that vector data compression does not consider the optimality of line simplification. In the face of terabytes or even petabytes of data, problems arise such as low processing efficiency and long transmission time. Based on the shape-tree principle, the proposed method aims to reconstruct the organizational structure of a geographic element and establish a hierarchical representation model of the element based on its structure, realizing multiscale shape recognition and matching and searching geographic elements. Finally, the proposed method is compared with a model based on the wavelet transform and discrete Fourier transform. The results demonstrate the applicability and effectiveness of the proposed method in morphological expression with geospatial big data.

Mesenchymal stem cell (MSC) transplantation has been widely used as a potential treatment for a variety of diseases. However, the contradiction between the low survival rate of transplanted cells and the beneficial therapeutic effects has affected its clinical use. Lysosomes as organelles at the center of cellular recycling and metabolic signaling, play essential roles in MSC homeostasis. In the first part of this review, we summarize the role of lysosomal acidification dysfunction in MSC senescence. In the second part, we summarize some of the potential strategies targeting lysosomal proteins to enhance the therapeutic effect of MSCs.

BackgroundEstrogen deficiency-induced depression is closely associated with an imbalance in intestinal microbiota and inflammation. Prevotella histicola (P. histicola), an emerging probiotic, apparently improves inflammatory responses. This study aims to verify the antidepressant-like effects of P. histicola and clarify its potential mechanisms.MethodsMice were treated with P. histicola and cohousing after ovariectomy (OVX). The changes in depression-like behaviors among mice were examined by behavioral tasks, and alterations in the microbiota were detected through 16S rRNA sequencing. Changes in neuronal injury, protein synthesis, inflammatory factors, intestinal permeability, and nerve proliferation were observed by H&E, Nissl staining, qRT-PCR, western blotting, and immunofluorescence.ResultsP. histicola significantly reduces depression-like behaviors and neuronal damage induced by estrogen deficiency. Additionally, P. histicola significantly increases the abundance of intestinal flora, especially Lactobacillus and Akkermansia. Meanwhile, the cohoused mice also had a better emotional state and neutral structure compared with OVX mice. P. histicola was also found to upregulate tight junction proteins ZO-1, occludin, claudin-1, and MUC2 in the ileum and colon and reduce the levels of inflammatory factors VCAM, MCP-1, IL-6, IL-8, and TNF-α, mainly in the ileum, colon, and decrease the expression of COX-2, TLR4, Myd88, JNK, MCP-1, IL-6, IL-8, and TNF-α in the hippocampus. Moreover, significant downregulation of apoptosis (caspase-3 and caspase-8) and upregulation of neurotrophic factors (BDNF and Ki-67) were observed after P. histicola treatment.ConclusionOur data show that P. histicola significantly mitigates depression of OVX mice through improvement in intestinal microbiota to repair intestinal leakage and inhibit central inflammation to promote the expression of BDNF for hippocampal neurogenesis. P. histicola may be therapeutically beneficial for PMD.

We report our analysis results for the globular cluster (GC) NGC 6341 (M92), as a millisecond pulsar (MSP) J1717+4308A has recently been reported found in this GC. The data used are from the Large Area Telescope onboard the Fermi Gamma-ray Space Telescope (Fermi). We detect γ -ray pulsations of the MSP at a 4.4 σ confidence level (the corresponding weighted H-test value is ∼28.4). This MSP, the fourth γ -ray pulsar found in a GC, does not have significant off-pulse emission and has γ -ray luminosity and efficiency 1.3 × 10 ^34 erg s ^−1 and 1.7%, respectively. In order to have a clear view on the properties of the known GC γ -ray MSPs, we reanalyze the Fermi-LAT data for the other three ones. These four MSPs share the properties of either having high $\dot{E}$ (∼10 ^36 erg s ^−1 ) or being in the GCs that contain only limited numbers of known MSPs. In addition, we find that PSRs J1823−3021A and B1821−24, in NGC 6624 and NGC 6626, respectively, have detectable off-pulse γ -ray emission and PSR J1835−3259B in NGC 6652 does not. Using the obtained off-pulse spectra or spectral upper limits, we constrain the numbers of other MSPs in the four GCs. The results are consistent with the numbers of the radio pulsars reported in them. While at least in NGC 6624 and NGC 6626, the contribution of other MSPs to their observed γ -ray emission can not be ignored, our study indicates that the presence of a bright MSP could be the dominant factor for whether a GC is detectable at γ -rays or not.

Very-high-energy (VHE) observations have revealed approximately 100 TeV sources in our Galaxy, and a significant fraction of them are under investigation to understand their origin. We report our study of one of them, HESS J1844−030. It is found to be possibly associated with the supernova remnant (SNR) candidate G29.37 + 0.1, and detailed studies of the source region at radio and X-ray frequencies have suggested that this SNR is a composite one, containing a pulsar wind nebula (PWN) powered by a candidate young pulsar. As the GeV source 4FGL J1844.4−0306 is also located in the region with high positional coincidence, we analyze its γ -ray data obtained with the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. We determine the GeV γ -ray emission is extended, described with a log-parabola function. The obtained spectrum can be connected to that of the VHE source HESS J1844−030. Given these properties and those from multifrequency studies, we discuss the origin of the γ -ray emission by considering that the two γ -ray sources are associated. Our modeling indicates that while the TeV part would have either a hadronic (from the SNR) or a leptonic origin (from the putative PWN), the GeV part would arise from a hadronic process. Thus we conclude that 4FGL J1844.4−0306 is likely the GeV counterpart to G29.37 + 0.1.

We report on the detection of a γ -ray source at the position of the nearby star-forming galaxy (SFG) M83, which is found from our analysis of 14 yr of the data obtained with the Large Area Telescope on board the Fermi Gamma-ray Space Telescope (Fermi). The source is weakly detected, with a significance of ∼5 σ , and its emission can be described with an exponentially cutoff power law. At a distance of 4.61 Mpc, the source’s γ -ray luminosity is ∼1.4 × 10 ^39 erg s ^−1 , roughly along the correlation line between the γ -ray and IR luminosities determined for nearby SFGs. Because of the weak detection, the source spectrum can not be used for checking its similarity with those of other SFGs. Given the positional matches and the empirical expectation for γ -ray emission from M83 due to the galaxy’s star-forming activity, we conclude that the γ -ray source is the likely counterpart to M83. The detection thus adds another member to the group of approximately a dozen SFGs, whose γ -ray emissions mostly have a cosmic-ray origin.

PSR J0631+1036 is a middle-aged pulsar with properties similar to those of the nearby Geminga pulsar. It is bright in γ -rays, and has been noted as the only source possibly associated with the TeV source 3HWC J0631+107 (also the LHAASO J0631+1040). For understanding the nature of the TeV source, we analyze the GeV γ -ray data obtained with the Large Area Telescope on board the Fermi Gamma-ray Space Telescope for the source region. We are able to remove the pulsar’s emission from the region from timing analysis, and find that the region is rather clean without possible GeV γ -ray emission present as the counterpart to the TeV source. By comparing this pulsar to Geminga and considering the spectral feature of the TeV source, we argue that it is likely the TeV halo powered by the pulsar.

Teraelectronvolt halos have been suggested to be a common phenomenon associated with middle-aged pulsars. Based on our recent work on the middle-aged pulsar J0631+1036, which is the only known source positionally coincident with a hard teraelectronvolt γ -ray source and likely powers the latter as a teraelectronvolt halo, we select three candidate teraelectronvolt halos from the first Large High Altitude Air Shower Observatory (LHAASO) catalog of γ -ray sources. The corresponding pulsars, given by the positional coincidences and property similarities, are PSR J1958+2846, PSR J2028+3332, and PSR J1849-0001. We analyze the gigaelectronvolt γ -ray data obtained with the Large Area Telescope on board the Fermi Gamma-ray Space Telescope for the first two pulsars, as the last is γ -ray quiet. We remove the pulsed emissions of the pulsars from the source regions from timing analysis, and determine that there are no residual gigaelectronvolt emissions in the regions as any possible counterparts to the teraelectronvolt sources. Considering the previous observational results for the source regions and comparing the two pulsars to Geminga (and Monogem), the LHAASO-detected teraelectronvolt sources are likely the pulsars’ respective teraelectronvolt halos. We find that the candidate and identified teraelectronvolt halos, including that of PSR J1849-0001, have luminosities at 50 TeV (estimated from the differential fluxes) approximately proportional to the spin-down energy $\dot{E}$ of the pulsars, and the ratios of the former to the latter are ∼6 × 10 ^−4 .

We conduct searches for γ-ray emission from the binary black-hole (BBH) mergers reported in the Gravitational-Wave Candidate Event Database (GraceDB). The γ-ray data are from the all-sky survey of the Large-Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope (Fermi), which allows searches for events of given time durations in large sky areas. The Two-Micron All-Sky Survey Photometric Redshift Catalog (2MPZ) is used for target selection, from which galaxy sources within the 90% credible areas and the distance ranges given by the gravitational-wave (GW) detections are determined. Excluding those BBH cases with large credible areas and/or dense fields (containing too many 2MPZ sources), searches for short transient events over the time duration of from −1 to 100 days of a trigger time for seven BBH mergers are conducted. We find two candidate short flaring events in the field of the GW event S200311bg and one in that of S190408an. However, the flaring events all have low significance (after considering the trial factor), and the third one appears off the position of the target galaxy. We discuss one of them from the first field that is detected in different short time-bin data and suggest that it is possibly a real flare arising from a radio galaxy. More such studies for the near-future GW detection run are planned, for which we will adjust our search strategy to be more effective and target flares of various time scales.

PKS 2247–131 is an active galaxy that has been emitting gamma-ray flares since October 2016. Here, the authors used data obtained with the Fermi Gamma-ray Space Telescope to find that PKS 2247–131 presents a relatively short, month-like flux oscillation at gamma-ray energies of 0.1–300 GeV.

This paper is devoted to studying a class of modified Kirchhoff-type equations \begin{equation*} -\Big(a+b\int_{\mathbb{R}^{3}}|\nabla u|^{2}dx\Big)\Delta u+V(x)u-u\Delta(u^2)=f(x,u),\hspace{0.5cm} \mbox{in}\ \mathbb{R}^3, \end{equation*} where $a>0, b\geq 0$ are two constants and $V:\R^{3}\rightarrow \R$ is a potential function. The existence of non-trivial solution to the above problem is obtained by the perturbation methods. Moreover, when $u>0$ and $f(x,u)=f(u)$, under suitable hypotheses on $V(x)$ and $f(u)$, we obtain the existence of a positive ground state solution by using a monotonicity trick and a new version of global compactness lemma. The character of this work is that for $f(u)\sim|u|^{p-2}u$ we prove the existence of a positive ground state solution in the case where $p\in(2,3]$, which has few results for the modified Kirchhoff equation. Hence our results improve and extend the existence results in the related literatures.

We are starting a project to find γ -ray millisecond pulsars (MSPs) among the unidentified sources detected by the Large Area Telescope (LAT) onboard the Fermi Gamma-Ray Space Telescope (Fermi), by radio observations. The selection of good candidates from analysis of the LAT data is an important part of the project. Given that there is more than 10 years worth of LAT data and the advent of the newly released LAT 8-year point source list (FL8Y), we have conducted a selection analysis, on the basis of our previous analysis, and report the results here. Setting the requirements for the unidentified sources in FL8Y of Galactic latitudes | b | > 5 ∘ and curvature significances >3 σ , there are 202 sources with detection signficances >6 σ . We select 57 relatively bright ones (detection significances >15 σ ) and analyze their 10.2 years of LAT data. Their variability is checked to exclude variable sources (likely blazars), test statistic maps are constructed to avoid contaminated sources, and curvature significances are re-obtained and compared to their γ -ray spectra to exclude non-significant sources. In the end, 48 candidates are found. Based on the available information, mostly from multi-wavelength studies, we discuss the possible nature of several of the candidates. Most of these candidates are currently being observed with the 65-meter Shanghai Tian Ma Radio Telescope.