The rise and fall of the high-energy afterglow emission of GRB 180720B

The Gamma Ray Burst (GRB) 180720B is one of the brightest events detected by the Fermi satellite and the first GRB detected by the H.E.S.S. telescope above 100 GeV. We analyse the Fermi (GBM and LAT) and Swift (XRT and BAT) data and describe the evolution of the burst spectral energy distribution in the 0.5 keV - 10 GeV energy range over the first 500 seconds of emission. We reveal a smooth transition from the prompt phase, dominated by synchrotron emission in a moderately fast cooling regime, to the afterglow phase whose emission has been observed from the radio to the GeV energy range. The LAT (0.1 - 100 GeV) light curve initially rises ($F_{\rm LAT}\propto t^{2.4}$), peaks at $\sim$78 s, and falls steeply ($F_{\rm LAT}\propto t^{-2.2}$) afterwards. The peak, which we interpret as the onset of the fireball deceleration, allows us to estimate the bulk Lorentz factor $\Gamma_{0}\sim 150 \ (300)$ under the assumption of a wind-like (homogeneous) circum-burst medium density. We derive a flux upper limit in the LAT energy range at the time of H.E.S.S. detection, but this does not allow us to unveil the nature of the high energy component observed by H.E.S.S. We fit the prompt spectrum with a physical model of synchrotron emission from a non-thermal population of electrons. The 0 - 35 s spectrum after its $E F(E)$ peak (at 1 - 2 MeV) is a steep power law extending to hundreds of MeV. We derive a steep slope of the injected electron energy distribution $N(\gamma)\propto \gamma^{-5}$. Our fit parameters point towards a very low magnetic field ($B'\sim 1$ G) in the emission region.Comment: 10 pages, 6 figures, submitted to A&

Detection of Hazelnut Oil in Virgin Olive Oil by Assessment of Free Sterols and Triacylglycerols

Free sterols were evaluated as factors for discriminating between genuine virgin olive oil and hazelnut-mixed virgin olive oil. Numeric analyses of the results amplified the differences between groups. The application of this method to virgin olive oil samples and their mixtures with 10% hazelnut oil distinguished between genuine and nongenuine virgin olive oil with statistical certainty. Triacylglycerol analysis was tested for the same purpose by using parameter \u394ECN42, but although it possessed a discriminating capacity, it alone could not distinguish the aforementioned groups with sufficient certainty. Free \u3947-sterols data were combined with \u394ECN42 data into a single discriminating function to improve differentiation and bring more ruggedness, and for detection of low amounts (10%) of hazelnut oil in virgin olive oil. In fact, the values obtained by addition of \u3947-sterol data and \u394ECN42 data showed a higher discriminating capacity than single parameters. In a single operation the method produced all the oil fractions necessary for analysis of free sterols and triacylglycerols with ECN42. Solid-phase extraction was applied in substitution of traditional chromatography on a silica column

Prospective randomized study on bilateral above-knee femoropopliteal revascularization: polytetrafluoroethylene versus reversed saphenous vein.

ABSTRACT. Objective: Some controversy exists as to whether polytetrafluoroethylene (PTFE) is equivalent to reversed saphenous vein (SV) as bypass graft material for the above-knee (AK) femoropopliteal revascularization. The purpose of this study was to compare the 5-year patency rate of reversed SV and PTFE grafts in claudicant patients who underwent bilateral AK femoropopliteal revascularizations. Methods: Between January 1994 and December 1997, 51 patients (102 limbs) with bilateral disabling claudication due to superficial femoral artery occlusion were treated with SV AK femoropopliteal bypass on one limb and with PTFE AK femoropopliteal bypass on the other. They were randomly selected for sequential surgical treatment involving either SV/PTFE or PTFE/SV. Kaplan-Meier analysis was used to estimate the patency rates and various factors were analyzed to ascertain any association with revascularization failure. Results: There was no perioperative (30-day) limb loss or perioperative death. There were 5 late deaths (late survival rate: 90%). The mean follow-up was 59 months. In the SV group, 3 bypasses failed, requiring a reoperation in only one patient; in the PTFE group 8 bypasses failed leading to 5 reoperations. There was no statistically significant difference in primary “assisted” patency rate for the two grafts: 100%, 98% and 94% for SV bypasses and 96%, 84% and 84% for PTFE grafts (p = .09), after 1, 3 and 5 years, respectively. Conclusions: The overall results of this randomized study show that SV and PTFE grafts have statistically comparable patency rates when used in the AK location in claudicant patients. The use of SV does lead to fewer occlusions and reoperations, however

Patency and limb salvage rates after distal revascularization to unclampable calcified outflow arteries

ABSTRACT. Purpose. Severe circumferential calcification of the outflow artery during lower extremity distal revascularization is considered a poor prognostic factor for bypass graft patency. The aim of this study was to assess the influence of circumferential infrapopliteal arterial calcification on bypass patency and limb salvage rates, comparing patency and limb salvage rates in unclampable calcified distal outflow arteries with those observed in uncalcified distal outflow arteries. Methods. From July 1990 to July 1997, out of 441 distal bypass procedures performed by the same surgeon, 69 (16%, group I) involved unclampable calcified outflow vessels while 83 (19%, group II) outflow vessels were uncalcified; the other 289 (65%) had varying intermediate degrees of calcification and were not included in this analysis. All procedures were performed for limb-threatening ischemia and involved standard vein patch angioplasty of the distal anastomotic site, irrespective of the conduit used. Primary and secondary patency, limb salvage and survival rates were assessed using Kaplan-Meier analysis. Results. Groups were similar with regard to age, sex and atherosclerotic risk factors except for a higher incidence of diabetes mellitus (88% vs 65%, P = .001) and renal failure (17% vs 5%, P = .01), including dialysis dependency (P = .01), in group I. Gangrene as an indication for surgery was statistically more frequent in group I (49% vs 29%, P = .01). The distal anastomotic locations and types of conduit involved were similar in the two groups. The femoral inflow level was used more often in group II (63% vs 38%, P = .003), the popliteal in group I (32% vs 17%, P = .03). Follow-up ranged from 30 days to 144 months, with a mean of 69 months. None of the patients were lost during follow-up period. None of the patients died during the perioperative (30-day) period. Primary patency rates at 1, 3 and 5 years were 84%, 65% and 52% for group I and 89%, 76% and 69% for group II (P = .07. ). Secondary patency rates at 1, 3 and 5 years were 96%, 82% and 78% for group I and 96%, 85% and 82% for group II (P = .58). Limb salvage rates at 1, 3 and 5 years were 93%, 83% and 81% for group I and 97%, 90% and 86% for group II (P = .39). Conclusions. Distal revascularization to unclampable, severely calcified outflow arteries can achieve much the same results to those obtained in uncalcified outflow arteries. A circumferentially calcified distal recipient artery should not be considered a major obstacle to an attempt at limb salvage bypass surgery

Serine phospholipids as endocoids.

Unusual phospholipid effects may occur when their distribution in the membrane is altered or when uncontrolled metabolic reactions yield elevated concentrations of their short lived derivatives. Serine phospholipids are normally buried in the internal side of plasma membrane. Upon exposure to the extracellular environment they elicit a response from selected cell populations. The interaction between these phospholipids and neuroactive compounds in rat peritoneal mast cells may indicate that serine phospholipids have a role in the nervous system during development