7 research outputs found
Cythère : société et économie pendant la période de la domination vénitienne
Get PDFThe occupation of Kythira after the Fourth Crusade by the patricianfamily of Venier, who held it as a fief till the intervention in 1363 of Venice,which placed the island under its direct control, influenced the population’ssocial and economic life. Using archival sources, conserved in the LocalHistorical Archives, the author examines the nature of the terzaria imposed by the conquerors upon the inhabitants, and studies its consequences on the social and demographic situation of the island
Polarimetry of the transient relativistic jet of GRB 110328/Swift J164449.3+573451
Get PDFWe present deep infrared (Ks-band) imaging polarimetry and radio (1.4- and 4.8-GHz) polarimetry of the enigmatic transient Swift J164449.3+573451. This source appears to be a short-lived jet phenomenon in a galaxy at redshift z= 0.354, activated by a sudden mass accretion on to the central massive black hole, possibly caused by the tidal disruption of a star. We aim to find evidence for this scenario through linear polarimetry, as linear polarization is a sensitive probe of jet physics, source geometry and the various mechanisms giving rise to the observed radiation. We find a formal Ks-band polarization measurement of Plin= 7.4 ± 3.5 per cent (including systematic errors). Our radio observations show continuing brightening of the source, which allows sensitive searches for linear polarization as a function of time. We find no evidence of linear polarization at radio wavelengths of 1.4 and 4.8 GHz at any epoch, with the most sensitive 3σ limits as deep as 2.1 per cent. These upper limits are in agreement with expectations from scenarios in which the radio emission is produced by the interaction of a relativistic jet with a dense circumsource medium. We further demonstrate how polarization properties can be used to derive properties of the jet in Swift J164449.3+573451, exploiting the similarities between this source and the afterglows of gamma-ray bursts
THE FERMI GBM GAMMA-RAY BURST SPECTRAL CATALOG: FOUR YEARS OF DATA
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Detailed optical and near-infrared polarimetry, spectroscopy and broad-band photometry of the afterglow of GRB 091018 : polarization evolution
Get PDFFollow-up observations of large numbers of gamma-ray burst (GRB) afterglows, facilitated by the Swift satellite, have produced a large sample of spectral energy distributions and light curves, from which their basic micro- and macro-physical parameters can in principle be derived. However, a number of phenomena have been observed that defy explanation by simple versions of the standard fireball model, leading to a variety of new models. Polarimetry can be a major independent diagnostic of afterglow physics, probing the magnetic field properties and internal structure of the GRB jets. In this paper we present the first high-quality multi-night polarimetric light curve of a Swift GRB afterglow, aimed at providing a well-calibrated data set of a typical afterglow to serve as a benchmark system for modelling afterglow polarization behaviour. In particular, our data set of the afterglow of GRB 091018 (at redshift z = 0.971) comprises optical linear polarimetry (R band, 0.13-2.3d after burst); circular polarimetry (R band) and near-infrared linear polarimetry (Ks band). We add to that high-quality optical and near-infrared broad-band light curves and spectral energy distributions as well as afterglow spectroscopy. The linear polarization varies between 0 and 3per cent, with both long and short time-scale variability visible. We find an achromatic break in the afterglow light curve, which corresponds to features in the polarimetric curve. We find that the data can be reproduced by jet break models only if an additional polarized component of unknown nature is present in the polarimetric curve. We probe the ordered magnetic field component in the afterglow through our deep circular polarimetry, finding P circ < 0.15per cent (2σ), the deepest limit yet for a GRB afterglow, suggesting ordered fields are weak, if at all present. Our simultaneous R- and Ks-band polarimetry shows that dust-induced polarization in the host galaxy is likely negligible
When a standard candle flickers
No full textThe Crab Nebula is the only hard X-ray source in the sky that is both bright enough and steady enough to be easily used as a standard candle. As a result, it has been used as a normalization standard by most X-ray/gamma ray telescopes. Although small-scale variations in the nebula are well-known, since the start of science operations of the Fermi Gamma-ray Burst Monitor (GBM) in August 2008 a ∼ 7% (70 mcrab) decline has been observed in the overall Crab Nebula flux in the 15-50 keV band, measured with the Earth occultation technique. This decline is independently confirmed in the ∼ 15 - 50 keV band with three other instruments: the Swift Burst Alert Telescope (Swift/BAT), the Rossi X-ray Timing Explorer Proportional Counter Array (RXTE/PCA), and the INTErnational Gamma-Ray Astrophysics Laboratory Imager on Board INTEGRAL (IBIS). A similar decline is also observed in the ∼ 3 - 15 keV data from the RXTE/PCA and in the 50 - 100 keV band with GBM, Swift/BAT, and INTEGRAL/IBIS. The change in the pulsed flux measured with RXTE/PCA since 1999 is consistent with the pulsar spin-down, indicating that the observed changes are nebular. Correlated variations in the Crab Nebula flux on a ∼ 3 year timescale are also seen independently with the PCA, BAT, and IBIS from 2005 to 2008, with a flux minimum in April 2007. As of August 2010, the current flux has declined below the 2007 minimum. © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence
Infographic. Multiligament knee injury (MLKI) : an expert consensus statement on nomenclature, diagnosis, treatment and rehabilitation
No full textDATA AVAILABILITY STATEMENT :
Data are available upon reasonable request from the first author.Multiligament knee injuries (MLKIs) represent a heterogeneous spectrum of pathology. Clinical evaluation, diagnosis and management of these injuries remains controversial. In order to assess the existing literature evaluating the diagnosis and management of MLKIs, we performed a scoping review based on established methodology. This process established that the majority of the 417 articles identified relating to MLKI were composed of small retrospective studies, 30% were composed of narrative reviews presenting no original data and only 1% of articles represented level 1 evidence. Overall, 70% of included studies were published within the last 12 years, with over half (57%) originating from the USA. The lack of diversity within author and patient groups that comprise MLKI research was highlighted. Consistently contentious themes within MLKI management were highlighted, including nomenclature, choice of imaging, timing of surgical intervention, operative versus non-operative management and strategies for rehabilitation. Most importantly, this study highlighted a lack of current consensus on an accepted approach within multiple domains of management of MLKI.https://bjsm.bmj.comhj2024Sports MedicineSDG-03:Good heatlh and well-bein
Percutaneous Endoscopic Gastro-Jejunostomy (PEGJ): Could Drug Administation be the Only Indication for Insertion? The Levodopa/Carbidopa Infusion Treatment Experience. A Retrospective Evaluation of the Method
No full textEnteral feeding is the preferred means of nutritional support in patients unable to eat normally. Percutaneous endoscopic gastro-jejunostomy (PEGJ) is widely used in such cases. It is also accepted that medication will be administered through the tube. In patients with severe Parkinson’s disease, a continuous delivery system of levodopa/carbidopa, formulated as a gel suspension (Duodopa®), reaches the small intestine through a jejunostomy and represents an alternative treatment method. The continuous release results in less variability in levodopa serum concentrations and fewer motor fluctuations and dyskinesias compared to oral administration. The method requires a very good collaboration between neurologists and gastroenterologists and is used in specializing centers in patients as mentioned with severe disease. A modified percutaneous endoscopic gastrostomy (PEG) kit is placed under sedation. This allows the passage of a pig tail catheter which is advanced to the jejunum and a portable pump is attached on it through a specially designed tubing system. This is the only case, known to us, where PEGJ is inserted for drug administration. We present our experience of nine cases (7 males, 2 females, mean age 72.4 years) with a follow up of up to five years. In three patients the tubing system had to be changed; the first it was accidentally pulled out, the second because of bezoar formation around the intragastric part of the tube and the third because of knot formation at the intragastric part of the jejunal tube. At the end of this five year period, all patients agreed that the neurological benefit was welcome and they had all come in terms with the undoubted difficulties the procedure causes
