242 research outputs found
The BeppoSAX/GRBM catalog of GRBs: Current status
We report on the status of the GRB catalog obtained with the
BeppoSAX/GRBM instrument. Thanks to the GRBM response function now well calibrated for all directions we are converting the background subtracted count rate profiles of all GRBs in physical units with the evaluation of position, duration, peak flux, fluence, and spectral information. In this poster we present preliminary results of a sample of 8 GRBs which will appear in the GRBM catalog of GRBs now in
preparation
The Gamma--Ray Burst catalog obtained with the Gamma Ray Burst Monitor aboard BeppoSAX
We report on the catalog of Gamma--Ray Bursts (GRBs) detected with the Gamma
Ray Burst Monitor aboard the BeppoSAX satellite. It includes 1082 GRBs with
40--700 keV fluences in the range from to erg cm, and with 40--700 keV peak fluxes from to erg cms. We report in the catalog
some relevant parameters of each GRB and discuss the derived statistical
properties.Comment: 48 pages, 14 figures, 4 Tables. Accepted for publication in The
Astrophysical Journal Supplemen
Pinus cembra L. tree-ring data as a proxy for summer mass-balance variability of the Careser Glacier (Italian Rhaetian Alps)
Glacial extent and mass-balance are sensitive climate proxies providing solid information on past climatic conditions. However, series of annual mass balance measurements of more than sixty years are scarce. To our knowledge, this is the first time the latewood density data (MXD) of the Swiss stone pine (Pinus cembra L.) has been used to reconstruct the summer mass balance (Bs) of an Alpine glacier. The MXD-based Bs well correlates with a Bs reconstruction based on the May to September temperature. Winter precipitation has been used as independent proxy to infer the winter mass balance and to obtain an annual mass balance (Bn) estimate dating back to the glaciological year 1811/12. The reconstructed MXD/precipitation-based Bn well correlates with the data both of the Careser and of other Alpine glaciers measured by the glaciological method. A number of critical issues should be considered in both proxies including nonlinear response of glacial mass balance to temperature, bedrock topography, ice thinning and fragmentation, MXD acquisition and standardization methods, and finally the “divergence problem” responsible for the recent reduced dendroglaciological reconstructions using this stable and reliable proxy
Porphyrin-containing polyimide films deposited by high vacuum co-evaporation
Abstract Thin films of porphyrin-containing polyimide were produced by high vacuum co-evaporation of 4,4′-hexafluoroisopropylidene diphthalic anhydride (6FDA), 3,3′-diaminodiphenyl sulfone (DDS) and 5,10,15,20 meso-tetraphenyl porphyrin (TPP). The films were characterized by FT-IR analysis, optical absorption and emission spectroscopy. FT-IR analysis shows that the film matrix is comprised of only unreacted monomers. The conversion of monomers to polyamic acid and the following condensation to polyimide were studied by curing the samples at temperatures up to 240 °C. The amount of polyamic acid increases from room temperature to 120 °C, while at higher temperature it starts to condense to polyimide. Optical analysis shows that TPP is incorporated in the film matrix and its chemical state is determined by the interaction with the monomers, polyamic acid and polyimide. After curing the TPP molecules are finely dispersed in the polyimide matrix and their absorption and fluorescence properties are wholly preserved
Large scale structure and the generalised Chaplygin gas as dark energy
The growth of large scale structure is studied in a universe containing both
cold dark matter (CDM) and generalized Chaplygin gas (GCg). GCg is assumed to
contribute only to the background evolution of the universe while the CDM
component collapses and forms structures. We present some new analytical as
well as numerical results for linear and non-linear growth in such model. The
model passes the standard cosmological distance test without the need of a
cosmological constant (LCDM). But we find that the scenario is severely
constrained by current observations of large scale structure. Any small
deviations of the GCg parameters away from the standard Lambda dominated
cosmology (LCDM) produces substantial suppression for the growth of structures.Comment: 6 pages, matches version accepted for publication in Phys.Rev.D (in
press
Role of TGF-β1 haplotypes in the occurrence of myocardial infarction in young Italian patients
<p>Abstract</p> <p>Background</p> <p>Transforming growth factor beta 1 (TGF-β1) gene play an important role in the acute myocardial infarction (AMI), however no investigation has been conducted so far in young AMI patients.</p> <p>In this study, we evaluated the influence of TGF-β1 polymorphisms/haplotypes on the onset and progression of AMI in young Italian population.</p> <p>Methods</p> <p>201 cases and 201 controls were genotyped for three TGF-β1 polymorphisms (G-800A, C-509T and Leu10Pro). The main follow-up end-points (mean follow-up, 107 ± 49 months) were death, myocardial infarction or revascularization procedures.</p> <p>Results</p> <p>Significant risk factors were smoking (p < 10<sup>-4</sup>), family history for coronary artery disease (p < 10<sup>-4</sup>), hypercholesterolemia (p = 0.001) and hypertension (p = 0.002). The C-509T and Leu10Pro polymorphisms showed significant differences (p = 0.026 and p = 0.004) between cases and controls.</p> <p>The most common haplotypes revealed a possible protective effect (GCT, OR 0.75, 95% CI 0.57–0.99, p = 0.042) and an increased risk of AMI (GTC, OR 1.51, 95% CI 1.13–2.02, p = 0.005), respectively.</p> <p>No statistical differences were observed in genotype distribution in the follow-up study between the two groups: 61 patients with subsequent events (13 deaths) and 108 without events.</p> <p>Conclusion</p> <p>Even though our results need to be further confirmed in larger studies, this is the first study reporting on a possible role of TGFβ1 common haplotypes in the onset of AMI in young patients.</p
Novel correlations between spectroscopic and morphological properties of activated carbons from waste coffee grounds
Massive quantities of spent coffee grounds (SCGs) are generated by users around the world. Different processes have been proposed for SCG valorization, including pyrolytic processes to achieve carbonaceous materials. Here, we report the preparation of activated carbons through pyrolytic processes carried out under different experimental conditions and in the presence of various porosity activators. Textural and chemical characterization of the obtained carbons have been achieved through Brunauer–Emmett–Teller (BET), ESEM,13C solid state NMR, XPS, XRD, thermogravimetric and spectroscopic determinations. The aim of the paper is to relate these data to the preparation method, evaluating the correlation between the spectroscopic data and the physical and textural properties, also in comparison with the corresponding data obtained for three commercial activated carbons used in industrial adsorption processes. Some correlations have been observed between the Raman and XPS data
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