233 research outputs found
Hawking Radiation as Tunneling: the D-dimensional rotating case
The tunneling method for the Hawking radiation is revisited and applied to
the dimensional rotating case. Emphasis is given to covariance of results.
Certain ambiguities afflicting the procedure are resolved.Comment: Talk delivered at the Seventh International Workshop Quantum Field
Theory under the influence of External Conditions, QFEXT'05, september
05,Barcelona, Spain. To appear in Journal of Phys.
Semiclassical Methods for Hawking Radiation from a Vaidya Black Hole
We derive the general form of Hawking temperature for Vaidya black hole in
the tunneling pictures. This kind of black hole is regarded as the description
of a more realistic one since it's time dependent decreasing mass due to the
evaporation process. Clearly, the temperature would be time dependent as our
findings. We use the semiclassical methods, namely radial null geodesic and
complex paths methods. Both methods are found to give the same results. Then,
we discuss the possible form of corresponding entropy.Comment: REVTeX 4, 11 pages, no figures, accepted for publication in IJMPA;
v2: eq.5 is correcte
On tunneling across horizons
The tunneling method for stationary black holes in the Hamilton-Jacobi
variant is reconsidered in the light of various critiques that have been moved
against. It is shown that once the tunneling trajectories have been correctly
identified the method isfree from internal inconsistencies, it is manifestly
covariant, it allows for the extension to spinning particles and it can even be
used without solving the Hamilton-Jacobi equation. These conclusions borrow
support on a simple analytic continuation of the classical action of a
pointlike particle, made possible by the unique assumption that it should be
analytic in complexified Schwarzschild or Kerr-Newman spacetimes. A more
general version of the Parikh-Wilczek method will also be proposed along these
lines.Comment: Latex Document, 5 pages, 2 figures, title changed, abstract changed,
added references, results unchange
Permanent His-bundle pacing maintains long-term ventricular synchrony and left ventricular performance, unlike conventional right ventricular apical pacing
n/
Clinical recrudescence of chronic untreated P. malariae infection after BNT162b2 CoVID-19 vaccine
We described a case of clinical reactivation of chronic P. malariae infection following CoVID-19 vaccination with BNT162b2 (Pifzer-Biontech CoVID-19 vaccine) in a 48-year old Italian man.The patient came to our attention for fever of unknown origin show a quartan pattern (every third day) associated to splenomegaly, the onset of the fever occurred one month after CoVID-19 vaccination with BNT162b2. P. malariae was diagnosed using Carestartâ„¢ malaria rapid test and Polymerase-Chain Reaction. Post-vaccine transient reduction of immune reactivity is described in literature, although the mechanism is unknown
Cardiovascular Responses Induced by Obstructive Apnea Are Enhanced in Hypertensive Rats Due to Enhanced Chemoreceptor Responsivity
Spontaneously hypertensive rats (SHR), like patients with sleep apnea, have hypertension, increased sympathetic activity, and increased chemoreceptor drive. We investigated the role of carotid chemoreceptors in cardiovascular responses induced by obstructive apnea in awake SHR. A tracheal balloon and vascular cannulas were implanted, and a week later, apneas of 15 s each were induced. the effects of apnea were more pronounced in SHR than in control rats (Wistar Kyoto; WKY). Blood pressure increased by 57 +/- 3 mmHg during apnea in SHR and by 28 +/- 3 mmHg in WKY (p < 0.05, n = 14/13). the respiratory effort increased by 53 +/- 6 mmHg in SHR and by 34 +/- 5 mmHg in WKY. the heart rate fell by 209 +/- 19 bpm in SHR and by 155 +/- 16 bpm in WKY. the carotid chemoreceptors were then inactivated by the ligation of the carotid body artery, and apneas were induced two days later. the inactivation of chemoreceptors reduced the responses to apnea and abolished the difference between SHR and controls. the apnea-induced hypertension was 11 +/- 4 mmHg in SHR and 8 +/- 4 mmHg in WKY. the respiratory effort was 15 +/- 2 mmHg in SHR and 15 +/- 2 mmHg in WKY. the heart rate fell 63 +/- 18 bpm in SHR and 52 +/- 14 bpm in WKY. Similarly, when the chemoreceptors were unloaded by the administration of 100% oxygen, the responses to apnea were reduced. in conclusion, arterial chemoreceptors contribute to the responses induced by apnea in both strains, but they are more important in SHR and account for the exaggerated responses of this strain to apnea.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento CientÃfico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de NÃvel Superior (CAPES)Universidade Federal de São Paulo, Escola Paulista Med, Dept Physiol, São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Physiol, São Paulo, BrazilFAPESP: 2010/19705-6CNPq: 472187/2010-4Web of Scienc
Profile of Trypanosoma cruzi Infection in a Tropical Medicine Reference Center, Northern Italy
Chagas disease (CD) is endemic in Central and South America, Mexico and even in some areas of the United States. However, cases have been increasingly recorded also in non-endemic countries. The estimated number of infected people in Europe is in a wide range of 14000 to 181000 subjects, mostly resident in Spain, Italy and the United Kingdom
Role of ventricular tachycardia ablation in arrhythmogenic right ventricular cardiomyopathy
Arrhythmogenic right ventricular cardiomyopathy (ARVC) is characterized by progressive fibro-fatty replacement of the myocardium that represents the substrate for recurrent sustained ventricular tachycardia (VT). These arrhythmias characterize the clinical course of a sizeable proportion of patients and have significant implications for their quality of life and long-term prognosis. Antiarrhythmic drugs are often poorly tolerated and usually provide incomplete control of arrhythmia relapses. Catheter ablation is a potentially effective strategy to treat frequent VT episodes and ICD shocks in ARVC patients. The aims of this review are to discuss the electrophysiological and electroanatomic substrates of ventricular tachycardia in patients with ARVC and to analyze the role of catheter ablation in their management with particular reference to selection of patients, technical issues, potential complications and outcomes
On the semiclassical treatment of Hawking radiation
In the context of the semiclassical treatment of Hawking radiation we prove
the universality of the reduced canonical momentum for the system of a massive
shell self gravitating in a spherical gravitational field within the Painlev\'e
family of gauges. We show that one can construct modes which are regular on the
horizon both by considering as hamiltonian the exterior boundary term and by
using as hamiltonian the interior boundary term. The late time expansion is
given in both approaches and their time Fourier expansion computed to reproduce
the self reaction correction to the Hawking spectrum.Comment: 18 pages, LaTeX, Corrected typo
Hawking radiation as tunneling and the unified first law of thermodynamics at the apparent horizon in the FRW universe
Relations between the tunneling rate and the unified first law of
thermodynamics at the apparent horizon of the FRW universe are investigated.
The tunneling rate arises as a consequence of the unified first law of
thermodynamics in such a dynamical system. The analysis shows obviously how the
tunneling is intimately connected with the unified first law of thermodynamics
through the principle of conservation of energy.Comment: Latex, 9 pages, no figur
- …