Search results for " TRANSIENT"

Peltier cells as temperature control elements: Experimental characterization and modelling

2014

Noisy dynamics in long and short Josephson junctions

The study of nonlinear dynamics in long Josephson junctions and the features of a particular kind of junction realized using a graphene layer, are the main topics of this research work. The superconducting state of a Josephson junction is a metastable state, and the switching to the resistive state is directly related to characteristic macroscopic quantities, such as the current the voltage across the junction, and the magnetic field through it. Noise sources can affect the mean lifetime of this superconducting metastable state, so that noise induced effects on the transient dynamics of these systems should be taken into account. The long Josephson junctions are investigated in the sine-Gor…

Prediction of Esophageal Varices by Liver Stiffness and Platelets in Persons with HIV infection and Compensated Advanced Chronic Liver Disease

2019

In Press.

Early warning for VHE gamma-ray flares with the ARGO-YBJ detector

2011

Detecting and monitoring emissions from flaring gamma-ray sources in the very-high-energy (VHE, > 100 GeV) band is a very important topic in gamma-ray astronomy. The ARGO-YBJ detector is characterized by a high duty cycle and a wide field of view. Therefore, it is particularly capable of detecting flares from extragalactic objects. Based on fast reconstruction and analysis, real-time monitoring of 33 selected VHE extragalactic sources is implemented. Flares exceeding a specific threshold are reported timely, hence enabling the follow-up observation of these objects using more sensitive detectors, such as Cherenkov telescopes. (C) 2011 Elsevier B.V. All rights reserved.

INTEGRAL long-term monitoring of the Supergiant Fast X-ray Transient XTE J1739-302

2008

In the past few years, a new class of High Mass X-Ray Binaries (HMXRB) has been claimed to exist, the Supergiant Fast X-ray Transients (SFXT). These are X-ray binary systems with a compact companion orbiting a supergiant star which show very short and bright outbursts in a series of activity periods overimposed on longer quiescent periods. Only very recently the first attempts to model the behaviour of these sources have been published, some of them within the framework of accretion from clumpy stellar winds.Our goal is to analyze the properties of XTE J1739-302/IGR J17391-3021 within the context of the clumpy structure of the supergiant wind. We have used INTEGRAL and RXTE/PCA observations…

IBIS: The Imager on-board INTEGRAL

2003

The IBIS telescope is the high angular resolution gamma-ray imager on-board the INTEGRAL Observatory, successfully launched from Baikonur (Kazakhstan) the 17th of October 2002. This medium size ESA project, planned for a 2 year mission with possible extension to 5, is devoted to the observation of the gamma-ray sky in the energy range from 3 keV to 10 MeV (Winkler 2001). The IBIS imaging system is based on two independent solid state detector arrays optimised for low ( 15-1000 keV) and high ( 0.175-10.0 MeV) energies surrounded by an active VETO System. This high efficiency shield is essential to minimise the background induced by high energy particles in the highly excentric out of van All…

The Be/X-ray transient 4U0115+63/V635 Cassiopeiae : II. Outburst mechanisms

2001

We present multi-wavelength long-term monitoring observations of V635 Cas, the optical counterpart to the transient X-ray pulsar 4U0115+63. The evolution of emission lines and photometric magnitudes indicates that the Be star undergoes relatively fast ( ~3 - 5yr) quasi-cyclic activity, losing and reforming its circumstellar disc. We show that the general optical, infrared and X-ray behaviour can be explained by the dynamical evolution of the viscous circumstellar disc around the Be star. After each disc-loss episode, the disc starts reforming and grows until it reaches the radius at which the resonant interaction of the neutron star truncates it. At some point, the disc becomes unstable to …

First observations of the X-ray transient EXO 2030+375 with IBIS/ISGRI

2003

We present a first INTEGRAL observation of the 42s transient X-ray pulsar EXO 2030+375 with IBIS/ISGRI. The source was detected during Cyg X-1 observations in December 2002. We analyzed observations during the outburst period from 9 to 21 December 2002 with a total exposure time of ~770 kiloseconds. EXO 2030+375 was almost always detected during single ~30 minute exposures in the 18-45 energy bands. The source light curve shows the characteristic outburst shape observed in this source.

Cardiovascular Health in Migrants. Current status and issues for prevention. A Collaborative Multidisciplinary Task Force Report

2014

OBJECTIVES: To review information on cardiovascular health and migration, to stress the attention of researchers that much needs to be done in the collection of sound data in Italy and to allow policy makers identifying this issue as an important public health concern. BACKGROUND: In Italy, the rate of immigrants in the total number of residents increased from 2.5% in 1990 to 7.4% in 2010, and currently exceeds 10% in regions such as Lombardia, Emilia Romagna and Toscana. METHODS: A consensus statement was developed by approaching relevant Italian national scientific societies involved in cardiovascular prevention. Task force members were identified by the president and/or the boards of eac…

Noninvasive assessment of liver fibrosis in thalassaemia major patients by transient elastography (TE) - lack of interference by iron deposition.

2009

The correlation between liver stiffness, measured by transient elastography, liver fibrosis, using the histological METAVIR score, and iron overload, measured by atomic absorption spectrometry was evaluated in 56 homozygous-b-thalassaemics. Liver stiffness increased proportionally to liver fibrosis staging (r = 0Æ70; P > 0Æ001) independently of liver iron concentration (r = 0Æ01; P = 0Æ932). The area under the receiver-operating characteristic curve for prediction of cirrhosis was 0Æ997 (95% confidence interval [CI]: 0Æ925–1Æ000) with cut-off of 13 kPa with 100% sensitivity (95% CI: 69Æ0–100Æ0) and 95% specificity (95% CI: 84Æ2–99Æ3). Transient elastography is a reliable non-invasive tool f…