检索结果-南通市图书馆

The afterglow emission from a stratified jet in GRB 170817A

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2021年第7期21卷 223-233页

作者： Kang-Fa Cheng Xiao-Hong Zhao bin-bin zhang Jin-Ming Bai Yunnan Observatories Chinese Academy of SciencesKunming 650216China University of the Chinese Academy of Sciences Beijing 100049China Center for Astronomical Mega-Science Chinese Academy of SciencesBeijing 100101China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650216China School of Astronomy and Space Science Nanjing UniversityNanjing 210093China Key Laboratory of Modern Astronomy and Astrophysics(Nanjing University) Ministry of EducationNanjing 210046China Department of Physics and Astronomy University of Nevada Las VegasNV 89154USA

The afterglow of GRB 170817 A has been detected for more than three years,but the origin of the multi-band afterglow light curves remains under debate.A classical top-hat jet model is faced with difficulties in producing a shallow rise of the afterglow light curves as observed(E_(v) ∝ T^(0.8)).Here we reconsider the model of stratified ejecta with an energy profile of E(> Γβ)=E_0(Γβ)^(-k) as the origin of the afterglow light curves of the burst,where Γ and β are the Lorentz factor and speed of the ejecta,respectively.k is the power-law slope of the energy *** consider that the ejecta are collimated into *** kinds of jet evolutions are investigated,including a lateral-spreading jet and a non-lateral-spreading *** fit the multi-band afterglow light curves,including the X-ray data at one thousand days post-burst,and find that both the models of the spreading and non-spreading jets can fit the light curves well,but the observed angular size of the source and the apparent velocity of the flux centroid for the spreading jet model are beyond the observation limits,while the non-spreading jet model meets the observation *** of the best-fit parameters for the non-spreading jet model,such as the number density of the circumburst medium~10^(-2) cm^(-3) and the total jet kinetic energy E ~ 4.8 × 10^(51) erg,also appear *** best-fit slope of the jet energy profile is k ~*** results suggest that the afterglow of GRB 170817 A may arise from the stratified jet and that the lateral spreading of the jet is not significant.

关键词： gamma-ray burst:general stars:jets relativistic processes

Relationships between Relative Spectral Lags and Relative Widths of Gamma-ray Bursts

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Astronomy and Astrophysics 2007年第3期7卷 428-434页

作者： Zhao-Yang Peng Rui-Jing Lu Yi-Ping Qin bin-bin zhang National Astronomical Observatories / Yunnan Observatory Chinese Academy of Sciences Kunming 650011 Physics Department Guangxi University Nanning 530004 Center for Astrophysics Guangzhou University Guangzhou 510400 Graduate School of Chinese Academy of Sciences Beijing 100049

The phenomenon of gamma-ray burst （GRB） spectral lags is very common, but a definitive explanation has not yet been given. From a sample of 82 GRB pulses we find that the spectral lags are correlated with the pulse widths, however, there is no correlation between the relative spectral lags and the relative pulse widths. We suspect that the correlations between spectral lags and pulse widths might be caused by the Lorentz factor of the GRBs concerned. Our analysis on the relative quantities suggests that the intrinsic spectral lag might reflect other aspect of pulses than the aspect associated with the dynamical time of shocks or that associated with the time delay due to the curvature effect.

关键词： gamma-rays bursts - methods statistical - gamma-rays theory

Effect of dimensional expansion on carrier transport behaviors of the hexagonal Bi-based perovskite crystals

在线全文

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2022年第3期31卷 459-465,I0013页

作者： Qihao Sun Bao Xiao Leilei Ji Dou Zhao Jinjin Liu Wei zhang Menghua Zhu Wanqi Jie bin-bin zhang Yadong Xu State Key Laboratory of Solidification Processing&Key Laboratory of Radiation Detection Materials and Devices MIITSchool of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi'an 710072ShaanxiChina College of Chemistry Nankai UniversityTianjin 300071China School of Microelectronics Xidian UniversityXi’an 710072ShaanxiChina

All-inorganic Cs_(3)Bi_(2)I_(9)(CBI)halide perovskites are sought to be candidate for photoelectrical materials because of their low toxicity and satisfactory ***,the discrete molecular[Bi2I9]3−clusters limit the charge-transport ***,the defect halide perovskite based on trivalent Bi^(3+)is expanded to Cs_(3)Bi_(2)I_(6)Br_(3)(CBIB).Centimeter-size CBIB single crystal(Φ15×70 mm^(3))was grown by the vertical Bridgeman *** powder X-ray diffraction analysis shows that CBIB has structure with lattice parameters of a=b=8.223Å,c=10.024Å,α=β=90°andγ=120°.The density functional theory(DFT)calculations demonstrate that the charge density distribution was enhanced after the dimensional *** enhancement of carrier transport ability of(00l)in-plane is characterized before and after dimensional *** obtained CBIB(001)exhibited an electron mobility up to 40.03 cm^(2)V^(−1)s^(−1)by time-of-flight(TOF)technique,higher than 26.46 cm^(2)V^(−1)s^(−1)of CBI(001).Furthermore,the X-ray sensitivity increases from 707.81μC Gy^(−1)cm^(−2)for CBI(001)to 3194.59μC Gy−1 cm^(−2)for CBIB(001).This research will deepen our understanding of Bi-based perovskite materials and afford more promising strategies for lead-free perovskite optoelectronic devices modification.

关键词： Bi-based perovskite Dimensional expansion Carrier transport Bridgeman method Radiation detection

The electromagnetic and gravitational-wave radiations of X-ray transient CDF-S XT2

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2021年第2期21卷 180-186页

作者： Hou-Jun Lü Yong Yuan Lin Lan bin-bin zhang Jin-Hang Zou En-Wei Liang Guangxi Key Laboratory for Relativistic Astrophysics School of Physical Science and TechnologyGuangxi UniversityNanning 530004China School of Astronomy and Space Science Nanjing UniversityNanjing 210093China Key Laboratory of Modern Astronomy and Astrophysics(Nanjing University) Ministry of EducationNanjing 210093China Space Science and Technology Hebei Normal UniversityShijiazhuang 050000China

binary neutron star(NS)mergers may result in remnants of supra-massive or even stable NS,which have been supported indirectly by observed X-ray plateau of some gamma-ray burst(GRB)***,Xue et al.(2019)discovered an X-ray transient CDF-S XT2 that is powered by a magnetar from merger of double NS via X-ray plateau and following stepper ***,the decay slope after the plateau emission is slightly larger than the theoretical value of spin-down in electromagnetic(EM)dominated by losing its rotation *** this paper,we assume that the feature of X-ray emission is caused by a supra-massive magnetar central engine for surviving thousands of seconds to collapse into a black *** this scenario,we present the comparisons of the X-ray plateau luminosity,break time,and the parameters of magnetar between CDF-S XT2 and other short GRBs with internal plateau *** adopting the collapse time to constrain the equation of state(EOS),we find that three EOSs(GM1,DD2,and DDME2)are consistent with the observational *** the other hand,if the most released rotation energy of magnetar is dominated by GW radiation,we also constrain the upper limit of ellipticity of NS for given EOS,and its range is[0.32-1.3]×10^(-3).Its GW signal cannot be detected by Advanced LIGO or even for more sensitive Einstein Telescope in the future.

关键词： stars magnetars

Periodic Variation Studies of the Two Short Period W UMa-type Eclipsing binaries: LX Lyn and V0853 Aur

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2024年第1期24卷 273-284页

作者： Xu zhang bin zhang School of Physics and Electronic Science Guizhou Normal UniversityGuiyang 550001China Guizhou Provincial Key Laboratory of Radio Astronomy and Data Processing Guizhou Normal UniversityGuiyang 550025China

In this paper,new light curves(LCs) of contact eclipsing binary(CEB) systems LX Lyn and V0853 Aur are presented and analyzed by using the 2015 version of the Wilson-Devinney(W-D) *** order to explain their asymmetric LCs,cool starspots on the components were *** is suggested that their fill-out degrees are f=12.0%(LX Lyn) and f=26.3%(V0853 Aur).At the same time,we found that LX Lyn is a W-type eclipsing binary(EB) with an orbital inclination of i=84°.88 and a mass ratio of q=2.31.V0853 Aur is also a W-type CEB with a mass ratio of q=2.77 and an orbital inclination of i= 79°.*** on all available times of light minimum,their orbital period changes are studied by using the O-C *** O-C diagram of LX Lyn reveals a cyclic oscillation with a period of about 14.84 yr and an amplitude of 0.0019 days,which can be explained by the light-travel time effect(LTTE) due to the presence of a third body with a minimum mass of0.06M_⊙.For V0853 Aur,it is discovered that the O-C diagram of the system also shows a cyclic oscillation with a period of 9.64 yr and an amplitude of 0.03365 *** cyclic oscillation of V0853 Aur can be attributed to the LTTE by means of a third body with a mass no less than 3.77M_⊙.The third body may play an important role in the formation and evolution of these systems.

关键词： stars:activity (stars:)binaries(including multiple):close (stars:)binaries:eclipsing (stars:)brown dwarfs stars:evolution stars:formation

Three-dimensional time-of-flight magnetic resonance angiography combined with high resolution T2-weighted imaging in preoperative evaluation of microvascular decompression

在线全文

学校读者我要写书评

暂无评论

World Journal of Clinical Cases 2022年第34期10卷 12594-12604页

作者： Chen Liang Ling Yang bin-bin zhang Shi-Wen Guo Rui-Chun Li Department of Neurosurgery The First Affiliated Hospital of Xi’an Jiaotong UniversityXi’an 710061Shaanxi ProvinceChina Department of Radiology Medical Physics University Medical Center FreiburgUniversity of FreiburgFreiburg 79108Germany Department of Aviation Psychology Research Xi’an Civil Aviation HospitalXi’an 710082Shaanxi ProvinceChina

BACKGROUND Neurovascular compression(NVC) is the main cause of primary trigeminal neuralgia(TN) and hemifacial spasm(HFS). Microvascular decompression(MVD) is an effective surgical method for the treatment of TN and HFS caused by NVC. The judgement of NVC is a critical step in the preoperative evaluation of MVD, which is related to the effect of MVD treatment. Magnetic resonance imaging(MRI) technology has been used to detect NVC prior to MVD for several years. Among many MRI sequences, three-dimensional time-of-flight magnetic resonance angiography(3D TOF MRA) is the most widely used. However, 3D TOF MRA has some shortcomings in detecting NVC. Therefore, 3D TOF MRA combined with high resolution T2-weighted imaging(HR T2WI) is considered to be a more effective method to detect *** To determine the value of 3D TOF MRA combined with HR T2WI in the judgment of NVC, and thus to assess its value in the preoperative evaluation of *** Related studies published from inception to September 2022 based on PubMed, Embase, Web of Science, and the Cochrane Library were retrieved. Studies that investigated 3D TOF MRA combined with HR T2WI to judge NVC in patients with TN or HFS were included according to the inclusion criteria. Studies without complete data or not relevant to the research topics were excluded. The Quality Assessment of Diagnostic Accuracy Studies checklist was used to assess the quality of included studies. The publication bias of the included literature was examined by Deeks’ test. An exact binomial rendition of the bivariate mixed-effects regression model was used to synthesize data. Data analysis was performed using the MIDAS module of statistical software Stata 16.0. Two independent investigators extracted patient and study characteristics, and discrepancies were resolved by consensus. Individual and pooled sensitivities and specificities were calculated. The I_(2) statistic and Q test were used to test heterogeneity. The study was registered on th

关键词： Three-dimensional time-of-flight magnetic resonance angiography High resolution T2 weighted imaging Neurovascular compression Microvascular decompression Meta-analysis

Spontaneous remission of autoimmune pancreatitis: Four case reports

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Clinical Cases 2022年第23期10卷 8232-8241页

作者： bin-bin zhang Jian-Wei Huo Zheng-Han Yang Zhen-Chang Wang Er-Hu Jin Department of Radiology Beijing Friendship HospitalCapital Medical UniversityBeijing 100050China Department of Radiology Beijing Hospital of Traditional Chinese MedicineCapital Medical UniversityBeijing 100010China

BACKGROUND Autoimmune pancreatitis(AIP)is a particular type of chronic pancreatitis,and steroid treatment of AIP is *** remission(SR)of AIP without steroids is relatively *** international consensus for the treatment of autoimmune pancreatitis suggests that patients with AIP with obstructive jaundice,abdominal pain,and back pain related to the pancreas or the bile duct should be treated with steroids;most asymptomatic patients with AIP may improve without ***,in our clinical work,we found that the clinical characteristics of AIP patients with SR *** of these cases are described *** addition,to our knowledge,there is no previously published report of dynamic imaging before and after SR of AIP at *** SUMMARY We present the cases of four patients with AIP(two females and two males)in which the AIP improved spontaneously without steroid *** patients were asymptomatic,one patient had abdominal pain with obstructive jaundice,and one patient had intermittent right upper abdominal *** patients presented with localized pancreatic enlargement and one with diffuse pancreatic *** addition to the pancreatic lesions,bile duct involvement was seen in two patients,and no extra-pancreatic organ involvement was found in the other two *** serum IgG4 level of all patients was more than twice the normal *** SR in the four patients,the affected pancreases exhibited three types of image features:Return to normal,progressive fibrosis,and atrophy and *** The clinical features of SR in our four patients with AIP differ,but the imaging findings share some *** SR,in some cases the affected pancreas could return to normal,although some patients suffer from progressive fibrosis and atrophy as well as calcification.

关键词： Autoimmune pancreatitis Spontaneous remission Computed tomography Magnetic resonance imaging Case report

Probing the Progenitor of High-z Short-duration GRB 201221D and its Possible Bulk Acceleration in Prompt Emission

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2022年第7期22卷 176-190页

作者： Hao-Yu Yuan Hou-Jun Lü Ye Li bin-bin zhang Hui Sun Jared Rice Jun Yang En-Wei Liang Guangxi Key Laboratory for Relativistic Astrophysics Department of PhysicsGuangxi UniversityNanning 530004China Purple Mountain Observatory Chinese Academy of SciencesNanjing 210008China Key Laboratory of Modern Astronomy and Astrophysics(Nanjing University) Ministry of EducationNanjing 210093China Key Laboratory of Space Astronomy and Technology National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China Department of Mathematics and Physical Science Southwestern Adventist UniversityKeeneTX 76059USA

The growing observed evidence shows that the long-and short-duration gamma-ray bursts(GRBs) originate from massive star core-collapse and the merger of compact stars,*** 201221 D is a short-duration GRB lasting~0.1 s without extended emission at high redshift z=*** analyzing data observed with the Swift/BAT and Fermi/GBM,we find that a cutoff power-law model can adequately fit the spectrum with a soft E=113keV,and isotropic energy E=1.36× *** order to reveal the possible physical origin of GRB 201221 D,we adopted multi-wavelength criteria(e.g.,Amati relation,ε-parameter,amplitude parameter,local event rate density,luminosity function,and properties of the host galaxy),and find that most of the observations of GRB 201221 D favor a compact star merger ***,we find that α is larger than 2+βin the prompt emission phase which suggests that the emission region is possibly undergoing acceleration during the prompt emission phase with a Poynting-flux-dominated jet.

关键词： (stars:)gamma-ray burst:individual(GRB 201221D) stars:massive acceleration of particles

Comparison of modified gunsight suture technique and traditional interrupted suture in enterostomy closure

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2023年第29期29卷 4571-4579页

作者： Chang Chen Xiang zhang Zhi-Qiang Cheng bin-bin zhang Xin Li Ke-Xin Wang Yong Dai Yan-Lei Wang Department of Colorectal Surgery Qilu HospitalShandong UniversityJinan 250012Shandong ProvinceChina Department of Nursing Qilu Hospital of Shandong University De Zhou HospitalDezhou 254300Shandong ProvinceChin Department of General Surgery Huantai Branch of Qilu Hospital of Shandong UniversityZibo 255000Shandong ProvinceChina

BACKGROUND Prophylactic enterostomy surgery is a common surgical approach used to reduce the risk of anastomotic leakage in patients who have undergone partial intestinal resection due to trauma or ***,the traditional interrupted suturing technique used in enterostomy closure surgery has several issues,including longer surgical incisions and higher incision tension,which can increase the risk of postoperative *** address these issues,scholars have proposed the use of a“gunsight suture”*** technique involves using a gunsight incision instead of a traditional linear incision,leaving a gap in the center for the drainage of blood and fluid to reduce the risk of *** on this technique,we propose an improved gunsight suture technique.A drainage tube is placed at the lowest point of the incision and close the gap in the center of the gunsight suture,which theoretically facilitates early postoperative mobility and reduces the burden of dressing changes,thereby reducing the risk of postoperative *** To compare the effectiveness of improved gunsight suture technique with traditional interrupted suture in closing intestinal *** In this study,a retrospective,single-center case analysis was conducted on 270 patients who underwent prophylactic ileostomy closure surgery at the Department of Colorectal Surgery of Qilu Hospital from April 2017 to December *** patients were divided into two groups:135 patients received sutures using the improved gunsight method,while the remaining 135 patients were sutured with the traditional interrupted suture *** collected data on a variety of parameters,such as operation time,postoperative pain score,body temperature,length of hospital stays,laboratory indicators,incidence of incisional complications,number of wound dressing changes,and hospitalization ***-parametric tests and chi-square tests were utilized for data *** There were no statistica

关键词： Enterostomy Abdominal wound closure technique Suture techniques Surgical wound infection Hospital costs Hospital stay