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Search Results: 1 - 10 of 194972 matches for " Alessandra D’Abramo "
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Early Atherosclerosis in HIV Infected Subjects on Suppressive Antiretroviral Treatment: Role of Osteoprotegerin
Alessandra DAbramo,Claudia D’Agostino,Alessandra Oliva,Marco Iannetta,Gabriella D’Ettorre,Francesco Vullo,Massimo Mancone,Maria Rosa Ciardi,Claudio Maria Mastroianni,Vincenzo Vullo
ISRN AIDS , 2013, DOI: 10.1155/2013/737083
Abstract: Cardiovascular disease is increased in HIV-infected patients. Cytokines such as osteoprotegerin are implicated in atherosclerosis. The aim of our study was to evaluate the role of osteoprotegerin in the development and progression of atherosclerosis in HIV infected subjects on suppressive antiretroviral treatment. We enrolled 76 patients; 35 HIV infected men on suppressive Highly Active Antiretroviral Therapy with Framingham score <10%; 21 HIV negative individuals matched for age, gender, and Framingham score, and 20 subjects with Framingham score >10% as control groups. HIV positive subjects underwent echocardiography, electrocardiography, and heart multidetector computed tomography, whereas in HIV negative subjects, tomography was only performed in case of any abnormalities either in echocardiography or electrocardiography. In HIV positive patients, computed tomography showed stenosis in 51.4% of the subjects. Osteoprotegerin plasma levels were higher in HIV-infected patients than those in healthy controls but lower than in HIV negative subjects with Framingham score >10%. Higher osteoprotegerin plasma levels were found in HIV positive patients with grade I stenosis than in patients with grade II/III stenosis. In conclusion, in HIV infected subjects with Framingham score <10%, osteoprotegerin plasma concentrations are associated with atherosclerosis, in particular at the early stage of the process. 1. Introduction Cardiovascular disease (CVD) is an emerging and significant cause of morbidity and mortality in HIV-infected patients [1]. HIV itself and antiretroviral drugs may contribute to the increased risk of CVD. In addition to traditional risk factors (age, smoking, dyslipidemia, and diabetes), chronic viral infection, immune activation, and inflammation play a central role in vascular damage and endothelial dysfunction [2]. Proinflammatory cytokines such as interleukin (IL)-6 and IL-1 are associated with development and progression of atherosclerosis [3–7]; furthermore, new soluble markers including osteoprotegerin (OPG) have been shown to be involved in this process. The OPG/RANK (receptor activator of NF-kappaB)/RANKL (receptor activator of NF-kappaB ligand), member of TNF superfamily, is a key regulatory system in bone remodelling by regulating development and activation of osteoclasts [8–11]. Recent studies showed the implication of the OPG/RANKL system in vascular disease, especially in vascular calcification, atherosclerosis and plaque formation [12–15]. There are few data about the relationship between OPG and cardiovascular disease in HIV
Probabilita` e Paradosso (Probability and Paradox)
Germano D'Abramo,Barbara D'Abramo
Mathematics , 2007, DOI: 10.1393/gdf/i2004-10019-1
Abstract: In this paper we present three simple applications of probability and highlight and discuss their paradoxical flavour.
The Demon in a Vacuum Tube
Germano D'Abramo
Entropy , 2013, DOI: 10.3390/e15051916
Abstract: In the present paper, several issues concerning the second law of thermodynamics, Maxwell’s demon and Landauer’s principle are dealt with. I argue that if the demon and the system on which it operates without dissipation of external energy are made of atoms and molecules (gas, liquid or solid) in thermal equilibrium (whose behaviour is described by a canonical distribution), then the unavoidable reason why the demon cannot successfully operate resides in the ubiquity of thermal fluctuations and friction. Landauer’s principle appears to be unnecessary. I also suggest that if the behaviour of the demon and the system on which it acts is not always describable by a canonical distribution, as would happen for instance with the ballistic motion of electrons at early stages of thermionic emission, then a successful working demon cannot be ruled out a priori. A critical review of two recent experiments on thermionic emission Maxwell’s demons is also given.
Is thermo-ionic emission at room temperature exploitable?
Germano D'Abramo
Physics , 2009,
Abstract: In this brief note we describe two devices, a sort of flat and spherical capacitor, with which one should be able to test the possibility of creating a macroscopic voltage, and thus exploitable current, out of a single thermal source at room temperature. The basic idea is trivial and it makes use of a thermo-emitting cathode with work function as low as 0.7eV. The idea is not completely new, but our approach is simpler and neat. When implemented, it should allow to assess if approaches based on thermo-ionic materials at room temperature really violate the Second Law of Thermodynamics macroscopically.
On the exploitability of thermo-charged capacitors
Germano D'Abramo
Physics , 2009, DOI: 10.1016/j.physa.2010.10.031
Abstract: Recently [Physics Letters A, 374, (2010) 1801] the concept of vacuum capacitor spontaneously charged harnessing the heat from a single thermal reservoir at room temperature has been introduced, along with a mathematical description of its functioning and a discussion on the main paradoxical feature that seems to violate the Second Law of Thermodynamics. In the present paper we investigate the theoretical and practical possibility of exploiting a such thermo-charged capacitor as voltage/current generator: we show that if very weak provisos on the physical characteristics of the capacitor are fulfilled, then a non-zero current should flow across the device, allowing the generation of potentially usable voltage, current and electric power out of a single thermal source at room temperature. Preliminary results show that the power output is tiny but non-zero.
Thermo-charged capacitors and the Second Law of Thermodynamics
Germano D'Abramo
Physics , 2009, DOI: 10.1016/j.physleta.2010.02.056
Abstract: In this Letter we describe a vacuum spherical capacitor that generates a macroscopic voltage between its spheres harnessing the heat from a single thermal reservoir at room temperature. The basic idea is trivial and it makes use of two concentric spherical electrodes with different work functions. We provide a mathematical analysis of the underlying physical process and discuss its connections with the Second Law of Thermodynamics.
A posteriori reading of Virtual Impactors impact probability
Germano D'Abramo
Physics , 2002,
Abstract: In this paper we define the a posteriori probability W. This quantity is introduced with the aim of suggesting a reliable interpretation of the actual threat posed by a newly discovered Near Earth Asteroid (NEA), for which impacting orbital solutions (now commonly known as Virtual Impactors or VIs) can not be excluded on the basis of the available astrometric observations. The probability W is strictly related to the so-called background impact probability (that extrapolated through a statistical analysis from close encounters of the known NEA population) and to the annual frequency with which the impact monitoring systems (currently NEODyS-CLOMON at University of Pisa and SENTRY at NASA-JPL) find VIs among newly discovered asteroids. Of W we also provide a conservative estimate, which turns out to be of nearly the same order of the background impact probability. This eventually says to us what we already know: the fact that nowadays monitoring systems frequently find VIs among newly discovered asteroids does not make NEAs more threatening than they have ever been.
A thought experiment on consciousness
Germano D'Abramo
Physics , 2003,
Abstract: The Mind-Body Problem, which constitutes the starting point for a large part of the speculations about consciousness and conscious experience, can be re-stated in an equivalent way, using the `brain duplication' argument described in this paper. If we assume that consciousness follows from a peculiar organization of physical matter and energy, namely that it does not transcend physical reality, then the brain duplication argument gives a possible interesting physical characterization of the mind: namely, a sort of extensive interdependence of the brain with the whole surrounding physical world in giving rise to consciousness.
"Closed-loop" analysis of a thermo-charged capacitor
Germano D'Abramo
Physics , 2014,
Abstract: In this Letter, an explicit application of conservation of energy and zero net work principle around a closed path ("closed-loop" analysis) is carried out on a thermo-charged capacitor at equilibrium with ambient heat at uniform temperature. This analysis corroborates the results of previous studies [Phys.Lett.A 374 (2010) 1801, Physica A 390 (2011) 481] that a potential drop $\Delta V$ does actually occur at capacitor terminals. Finally, a conventional photoelectric emission experiment is proposed to indirectly text thermo-charged capacitor functioning.
Uranio impoverito: perché? (Depleted uranium: why?)
Germano D'Abramo
Physics , 2003,
Abstract: In this paper we develop a simple model of the penetration process of a long rod through an uniform target. Applying the momentum and energy conservation laws, we derive an analytical relation which shows how the penetration depth depends upon the density of the rod, given a fixed kinetic energy. This work was sparked off by the necessity of understanding the effectiveness of high density penetrators (e.g. depleted uranium penetrators) as anti-tank weapons.
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