Is the late near-infrared bump in short-hard GRB 130603B due to the Li-Paczynski kilonova?

Short-hard gamma-ray bursts (GRBs) are widely believed to be produced by the merger of two binary compact objects, specifically by two neutron stars or by a neutron star orbiting a black hole. According to the Li-Paczynski kilonova model, the merger would launch sub-relativistic ejecta and a near-infrared/optical transient would then occur, lasting up to days, which is powered by the radioactive decay of heavy elements synthesized in the ejecta. The detection of a late bump using the {\em Hubble Space Telescope} ({\em HST}) in the near-infrared afterglow light curve of the short-hard GRB 130603B is indeed consistent with such a model. However, as shown in this Letter, the limited {\em HST} near-infrared lightcurve behavior can also be interpreted as the synchrotron radiation of the external shock driven by a wide mildly relativistic outflow. In such a scenario, the radio emission is expected to peak with a flux of $\sim 100 \mu$Jy, which is detectable for current radio arrays. Hence, the radio afterglow data can provide complementary evidence on the nature of the bump in GRB 130603B. It is worth noting that good spectroscopy during the bump phase in short-hard bursts can test validity of either model above, analogous to spectroscopy of broad-lined Type Ic supernova in long-soft GRBs.Comment: 4 pages, 2 figures, published in ApJ Lette

A supra-massive magnetar central engine for short GRB 130603B

We show that the peculiar early optical and in particular X-ray afterglow emission of the short duration burst GRB 130603B can be explained by continuous energy injection into the blastwave from a supra-massive magnetar central engine. The observed energetics and temporal/spectral properties of the late infrared bump (i.e., the "kilonova") are also found consistent with emission from the ejecta launched during an NS-NS merger and powered by a magnetar central engine. The isotropic-equivalent kinetic energies of both the GRB blastwave and the kilonova are about $E_{\rm k}\sim 10^{51}$ erg, consistent with being powered by a near-isotropic magnetar wind. However, this relatively small value demands that most of the initial rotational energy of the magnetar $(\sim {\rm a~ few \times 10^{52}~ erg})$ is carried away by gravitational wave radiation. Our results suggest that (i) the progenitor of GRB 130603B would be a NS-NS binary system, whose merger product would be a supra-massive neutron star that lasted for about $\sim 1000$ seconds; (ii) the equation-of-state of nuclear matter would be stiff enough to allow survival of a long-lived supra-massive neutron star, so that it is promising to detect bright electromagnetic counterparts of gravitational wave triggers without short GRB associations in the upcoming Advanced LIGO/Virgo era.Comment: Five pages including 1 Figure, to appear in ApJ

FBG-Based Triaxial Force Sensor Integrated with an Eccentrically Configured Imaging Probe for Endoluminal Optical Biopsy

Accurate force sensing is important for endoluminal intervention in terms of both safety and lesion targeting. This paper develops an FBG-based force sensor for robotic bronchoscopy by configuring three FBG sensors at the lateral side of a conical substrate. It allows a large and eccentric inner lumen for the interventional instrument, enabling a flexible imaging probe inside to perform optical biopsy. The force sensor is embodied with a laser-profiled continuum robot and thermo drift is fully compensated by three temperature sensors integrated on the circumference surface of the sensor substrate. Different decoupling approaches are investigated, and nonlinear decoupling is adopted based on the cross-validation SVM and a Gaussian kernel function, achieving an accuracy of 10.58 mN, 14.57 mN and 26.32 mN along X, Y and Z axis, respectively. The tissue test is also investigated to further demonstrate the feasibility of the developed triaxial force senso

Reducing the Vulnerability of Electric Power Grids to Terrorist Attacks

Final Project ReportThis project (‘Reducing the Vulnerability of Electric Power Grids to Terrorist Attacks’) is collaborative research with the Naval Postgraduate School (NPS), under the sponsorship of the U.S. Department of Energy. The research at The University of Texas focuses on analyzing cascading outages in large-scale electricity grids, both as a standalone tool and also as a component to eventually be added to the Vulnerability of Electric Grids Analyzer (VEGA) [1]. We refer to the proposal (Wood, Salmeron and Baldick 2003), and references therein, for detailed background on the problem of electric power-grid vulnerability. In that document, goals were established for this research and its critical importance. One aspect of that research, conducted primarily at University of Texas at Austin (UT), is the development of a cascading analysis tool, building on the experiences of a prototype tool developed by Commonwealth Associates and described in a white paper [2]. This development is aimed at including the short-term effects of cascading outages into the analysis of network vulnerability. In addition to integrating representation of cascading outages into VEGA, informal feedback from industry suggested that it was also important that for this research to develop a standalone cascading analysis tool. Development as a standalone tool has also facilitated the division of activities between NPS and UT. This report details the development of the prototype standalone tool. Future work includes extending the types of initial disturbances that can be considered and integration of the tool with VEGA.DOE Research Project DE-FG02-05ER2567

Cooperative low-rank models for removing stripe noise from OCTA images

Optical coherence tomography angiography (OCTA) is an emerging non-invasive imaging technique for imaging the microvasculature of the eye based on phase variance or amplitude decorrelation derived from repeated OCT images of the same tissue area. Stripe noise occurs during the OCTA acquisition process due to the involuntary movement of the eye. To remove the stripe noise (or ‘destriping’) effectively, we propose two novel image decomposition models to simultaneously destripe all the OCTA images of the same eye cooperatively: cooperative uniformity destriping (CUD) model and cooperative similarity destriping (CSD) model. Both the models consider stripe noise by low-rank constraint but in different ways: the CUD model assumes that stripe noise is identical across all the layers while the CSD model assumes that the stripe noise at different layers are different and have to be considered in the model. Compared to the CUD model, CSD is a more general solution for real OCTA images. An efficient solution (CSD+) is developed for model CSD to reduce the computational complexity. The models were extensively evaluated against state-of-the-art methods on both synthesized and real OCTA datasets. The experiments demonstrated not only the effectiveness of the CSD and CSD+ models in terms of peak signal-to-noise ratio (PSNR) and structural similarity index (SSIM) and CSD+ is twice faster than CSD, but also their beneficiary effect on the vessel segmentation of OCTA images. We expect our models will become a powerful tool for clinical applications

Ginsenoside Rb1 Preconditioning Enhances eNOS Expression and Attenuates Myocardial Ischemia/Reperfusion Injury in Diabetic Rats

Diabetes mellitus is associated with decreased NO bioavailability in the myocardium. Ginsenoside Rb1 has been shown to confer cardioprotection against ischemia reperfusion injury. The aim of this study was to investigate whether Ginsenoside Rb1 exerts cardioprotective effects during myocardial ischemia-reperfusion in diabetic rats and whether this effect is related to increase the production of NO via enhancing eNOS expression in the myocardium. The myocardial I/R injury were induced by occluding the left anterior descending artery for 30 min followed by 120 min reperfusion. An eNOS inhibitor L-NAME or Rb1 were respectively administered 25 min or 10 min before inducing ischemia. Ginsenoside Rb1 preconditioning reduced myocardial infarct size when compared with I/R group. Ginsenoside Rb1 induced myocardial protection was accompanied with increased eNOS expression and NO concentration and reduced plasma CK and LDH (P < 0.05). Moreover, the myocardial oxidative stress and tissue histological damage was attenuated by Ginsenoside Rb1 (P < 0.05). L-NAME abolished the protective effects of Ginsenoside Rb1. It is concluded that Ginsenoside Rb1 protects against myocardium ischemia/reperfusion injury in diabetic rat by enhancing the expression of eNOS and increasing the content of NO as well as inhibiting oxidative stress

Effect of three kinds of anaesthetic drugs on postoperative recovery, regulatory T cells and T lymphoid cells in elderly patients

Purpose: To investigate the effect of three anaesthetic drugs on postoperative recovery, regulatory T cells and T cell subset levels in elderly patients.Methods: The patients were randomly divided into groups A, B and C (42 patients per group). Group A received intravenous remifentanil, dexamethasone, dexmedetomidine and propofol, followed by continuous intraoperative inhalation of sevoflurane and continuous intravenous pumping of remifentanil. Group B was given intravenous propofol and midazolam, followed by continuous intraoperative inhalation of sevoflurane, while Group C received intravenous etomidate and rocuronium, with continuous intraoperative inhalation of sevoflurane. The preoperative or 24-h postoperative T regulatory cells (CD4+ CD25+) and T cell subsets (CD4+ and CD8+) were determined for each group.Results: MMSE scores in the three groups were lower than their pre-operation scores (p &lt; 0.05). There were significant reductions in 24-h postoperative serum CD4+ CD25+ and CD4+ levels, with higher reductions in group B (p &lt; 0.05). In contrast, CD8+ increased in all groups, but was lower in group B than in the other two groups (p &lt; 0.05).Conclusion: These findings strongly suggest that propofol, midazolam and sevoflurane have rapid onset of action and recovery, which improves the comfort of patients while decreasing negative impact on the function of the immune system. Furthermore, these anaesthetic agents enhance the recovery of elderly patients.Keywords: Anaesthesia, Cognitive function, Regulatory T cells, T cell subset