7,649 research outputs found
A multi-flow model for microquasars
We present a new picture for the central regions of Black Hole X-ray
Binaries. In our view, these central regions have a multi-flow configuration
which consists in (1) an outer standard accretion disc down to a transition
radius r_J, (2) an inner magnetized accretion disc below r_J driving (3) a non
relativistic self-collimated electron-proton jet surrounding, when adequate
conditions for pair creation are met, (4) a ultra relativistic
electron-positron beam. This accretion-ejection paradigm provides a simple
explanation to the canonical spectral states, from radio to X/gamma-rays, by
varying the transition radius r_J and disc accretion rate independently. Large
values of r_J and low accretion rate correspond to Quiescent and Hard states.
These states are characterized by the presence of a steady electron-proton MHD
jet emitted by the disc below r_J. The hard X-ray component is expect to form
at the jet basis. When r_J becomes smaller than the marginally stable orbit
r_i, the whole disc resembles a standard accretion disc with no jet,
characteristic of the Soft state. Intermediate states correspond to situations
where r_J ~ r_i. At large accretion rate, an unsteady pair cascade process is
triggered within the jet axis, giving birth to flares and ejection of
relativistic pair blobs. This would correspond to the luminous intermediate
state, with its associated superluminal motions.Comment: 12 pages, 3 figures. Proceedings of ``High Energies in the
Highlands'', Fort-William, 27 June-1 July 200
UN'EFFICIENTE PROCEDURA DI CALCOLO PER L'ANALISI DI FATICA MULTIASSIALE MEDIANTE I CRITERI BASATI SULL'APPROCCIO DI PIANO CRITICO
In multiaxial fatigue analysis using the critical plane approach, the shear stress amplitude has to be evaluate using proper numerical procedures that elaborate the points of the curve described by the tip of the shear stress vector acting in the analyzed plane. The calculation has to be carried out in several planes centred in the analyzed material plane; furthermore, in the analysis of a component, it has to be repeated in several points. In this paper a procedure that allows to noticeably reduce both the number of planes and the number of points in which it is necessary to evaluate by means of the onerous procedures, with a considerable reduction of the computational times
Effect of insulin glargine on cardiovascular risk analysed by mean HRV
Type 2 diabetes mellitus is an insidious disease that is increasingly present in geriatric population [1]. The greatest difficulty is represented by glycaemic control in geriatric patients often not very compliant with diet therapy and drug therapy. A new insulin glargine 300 units/ml formulation seems im- prove patient compliance due to the lower volume of insulin to be injected and improved glycaemic control over 24 hours. The HRV signal, derived from digital electrocardiographic recording, is the simplest and most imme- diate analysis that consists in calculating some temporal parameters [2]. HRV is a simple statistics derived from beat-beat intervals of sinus origin expressed as units of time in milliseconds. Data in the literature indicate that a decrease in HRV, measured with time domain analysis, denotes a worse prognosis and/or an increased risk of mortality in patients with heart disease, especially in the elderly ones
FROM 2D TO 3D SUPERVISED SEGMENTATION AND CLASSIFICATION FOR CULTURAL HERITAGE APPLICATIONS
The digital management of architectural heritage information is still a complex problem, as a heritage object requires an integrated representation of various types of information in order to develop appropriate restoration or conservation strategies. Currently, there is extensive research focused on automatic procedures of segmentation and classification of 3D point clouds or meshes, which can accelerate the study of a monument and integrate it with heterogeneous information and attributes, useful to characterize and describe the surveyed object. The aim of this study is to propose an optimal, repeatable and reliable procedure to manage various types of 3D surveying data and associate them with heterogeneous information and attributes to characterize and describe the surveyed object. In particular, this paper presents an approach for classifying 3D heritage models, starting from the segmentation of their textures based on supervised machine learning methods. Experimental results run on three different case studies demonstrate that the proposed approach is effective and with many further potentials
Neutrons from Piezonuclear Reactions
We report the results obtained by cavitating water solutions of iron salts
(iron chloride and iron nitrate) with different concentrations at different
ultrasound powers. In all cases we detected a neutron radiation well higher
than the background level. The neutron production is perfectly reproducible and
can at some extent be controlled. These evidences for neutron emission
generated by cavitation support some preliminary clues for the possibility of
piezonuclear reactions (namely nuclear reactions induced by pressure and shock
waves) obtained in the last ten years. We have been able for the first time to
state some basic features of such a neutron emission induced by cavitation,
namely: 1) a marked threshold behavior in power, energy and time; 2) its
occurring without a concomitant production of gamma radiation.Comment: 8 figures; we added some more important references; we replaced some
figures with more detailed ones; we added more comprehensive details which
could not be desclosed before as part of private patents which have been
published no
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