view Abstract Citations (1) References (17) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Column Accretion with Radiation Drag and the Two-Branch Spectrum of the Low-Mass X-Ray Binary GX 5-1 You, J. H. ; Lu, T. ; Wei, C. Y. ; Wang, T. G. Abstract In order to explain the two-branch spectrum behavior of the low-mass X-ray binary (LMXB) GX 5-1, an improved column accretion model is suggested. The key point is that the viscous damping (radiation drag) in the column accretion process has to be taken into consideration. From this improved model, a theoretical hardness-inensity diagram is obtained which is a good fit with the observations. Publication: The Astrophysical Journal Pub Date: July 1992 DOI: 10.1086/171580 Bibcode: 1992ApJ...394..283Y Keywords: Accretion Disks; Stellar Spectra; Viscous Damping; X Ray Binaries; Computational Astrophysics; Radiation Pressure; Stellar Luminosity; Stellar Models; Stellar Oscillations; Stellar Temperature; Temperature Dependence; Astrophysics; ACCRETION; ACCRETION DISKS; STARS: BINARIES: CLOSE; STARS: INDIVIDUAL ALPHANUMERIC: GX 5-1; STARS: NEUTRON; X-RAYS: STARS full text sources ADS | data products SIMBAD (1)
White matter hyperintensities, one of the major markers of cerebral small vessel disease, disrupt the integrity of neuronal networks and ultimately contribute to cognitive dysfunction. However, a deeper understanding of how white matter hyperintensities related to the connectivity patterns of brain hubs at the neural network level could provide valuable insights into the relationship between white matter hyperintensities and cognitive dysfunction. A total of 36 patients with moderate to severe white matter hyperintensities (Fazekas score ≥ 3) and 34 healthy controls underwent comprehensive neuropsychological assessments and resting-state functional MRI scans. The voxel-based graph-theory approach-functional connectivity strength was employed to systematically investigate the topological organization of the whole-brain networks. The white matter hyperintensities patients performed significantly worse than the healthy controls in episodic memory, executive function and information processing speed. Additionally, we found that white matter hyperintensities selectively affected highly connected hub regions, predominantly involving the medial and lateral prefrontal, precuneus, inferior parietal lobule, insula and thalamus. Intriguingly, this impairment was connectivity distance-dependent, with the most prominent disruptions observed in long-range connections (e.g. 100-150 mm). Finally, these disruptions of hub connectivity (e.g. the long-range functional connectivity strength in the left dorsolateral prefrontal cortex) positively correlated with the cognitive performance in white matter hyperintensities patients. Our findings emphasize that the disrupted hub connectivity patterns in white matter hyperintensities are dependent on connection distance, especially longer-distance connections, which in turn predispose white matter hyperintensities patients to worse cognitive function.
Using a cross correlation method, we find that there may exist gamma-ray bursts whose soft emission has a time delay relative to the high-energy emission. Autocorrelation was used to determine the duration of substructures in different energy bands of selected bursts,in order to examine the correlation between time def ay and broadening of soft emission. The results indicate a positive correlation with correlation coefficient 0.75 between the two parameters, this suggests that scattering could partly be the mechanism of time delay and broadening. The hardness ratios of the bursts with time delays are concentrated in a relatively narrow range.
Currently popular models for progenitors of gamma-ray bursts (GRBs) are the mergers of compact objects and the explosions of massive stars. These two cases have distinctive environments for GRBs: compact object mergers occur in the interstellar medium (ISM) and the explosions of massive stars occur in the preburst stellar wind. We here discuss neutrino afterglows from reverse shocks as a result of the interaction of relativistic fireballs with their surrounding wind matter. After comparing with the analytical result of Waxman & Bahcall (2000) for the homogeneous ISM case, we find that the differential spectrum of neutrinos with energy from $\sim 3\times 10^{15}$ to $\sim 3\times 10^{17}$ eV in the wind case is softer by one power of the energy than in the ISM case. Furthermore, the expected flux of upward moving muons produced by neutrino interactions below a detector on the surface of the Earth in the wind case is $\sim 5$ events per year per km$^2$, which is about one order of magnitude larger than in the ISM case. In addition, these properties are independent of whether the fireballs are isotropic or beamed. Therefore, neutrino afterglows, if detected, may provide a way of distinguishing between GRB progenitor models based on the differential spectra of neutrinos and their event rates in a detector.
Abstract Glymphatic dysfunction has been correlated with cognitive decline, with a higher choroid plexus volume (CPV) being linked to a slower glymphatic clearance rate. Nevertheless, the interplay between CPV, glymphatic function, and cognitive impairment in white matter hyperintensities (WMHs) has not yet been investigated. In this study, we performed neuropsychological assessment, T1-weighted three-dimensional (3D-T1) images, and diffusion tensor imaging (DTI) in a cohort of 206 WMHs subjects and 43 healthy controls (HCs) to further explore the relationship. The DTI analysis along the perivascular space (DTI-ALPS) index, as a measure of glymphatic function, was calculated based on DTI. Severe WMHs performed significantly worse in information processing speed (IPS) than other three groups, as well as in executive function than HCs and mild WMHs. Additionally, severe WMHs demonstrated lower DTI-ALPS index and higher CPV than HCs and mild WMHs. Moderate WMHs displayed higher CPV than HCs and mild WMHs. Mini-Mental State Examination, IPS, and executive function correlated negatively with CPV but positively with DTI-ALPS index in WMHs patients. Glymphatic function partially mediated the association between CPV and IPS, indicating a potential mechanism for WMHs-related cognitive impairment. CPV may act as a valuable prognostic marker and glymphatic system as a promising therapeutic target for WMHs-related cognitive impairment.
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