Stationary Black Holes in a Generalized Three-Dimensional Theory of Gravity

We consider a generalized three-dimensional theory of gravity which is specified by two fields, the graviton and the dilaton, and one parameter. This theory contains, as particular cases, three-dimensional General Relativity and three-dimensional String Theory. Stationary black hole solutions are generated from the static ones using a simple coordinate transformation. The stationary black holes solutions thus obtained are locally equivalent to the corresponding static ones, but globally distinct. The mass and angular momentum of the stationary black hole solutions are computed using an extension of the Regge and Teitelboim formalism. The causal structure of the black holes is described.Comment: 12 pages, Late

Generation of Superposition States and Charge-Qubit Relaxation Probing in a Circuit

We demonstrate how a superposition of coherent states can be generated for a microwave field inside a coplanar transmission line coupled to a single superconducting charge qubit, with the addition of a single classical magnetic pulse for chirping of the qubit transition frequency. We show how the qubit dephasing induces decoherence on the field superposition state, and how it can be probed by the qubit charge detection. The character of the charge qubit relaxation process itself is imprinted in the field state decoherence profile.Comment: 6 pages, 4 figure

Pion-Pion Phase-Shifts and the Value of Quark-Antiquark Condensate in the Chiral Limit

We use low energy pion-pion phase-shifts in order to make distinction between the alternatives for the value of the quark-antiquark condensate $B_0$ in the chiral limit. We will consider the amplitude up to and including ${\cal O}(p^4)$ contributions within the Standard and Generalized Chiral Perturbation Theory frameworks. They are unitarized by means of Pad\'e approximants in order to fit experimental phase-shifts in the resonance region. As the best fits correspond to $\alpha = \beta = 1$, we conclude that pion-pion phase-shift analysis favors the standard ChPT scenario, which assumes just one, large leading order parameter $_{_0}$.Comment: 5 pages, 3 figures and 1 tabl

Arquiteturas funerárias, materiais de construção e interação com o espaço na Idade do Bronze da Serra da Freita (Centro-Norte de Portugal). O caso do tumulus de Laceiras do Côvo 3, Vale de Cambra

Pretende-se com este artigo dar a conhecer os resultados dos trabalhos arqueológicos levados a cabo no monu-mento funerário de Laceiras do Côvo 3, estrutura tumular enquadrável, provavelmente, na Idade do Bronze, localizada na freguesia de Arões, concelho de Vale de Cambra. Este monumento revela-se de particular inte-resse pela policromia intencional na matéria usada na sua construção e pela disposição cuidada dos elementos litológicos do tumulus, em que nada parece estar ao acaso. Tais características sugerem a intenção de manter o espaço dos mortos visível, assim como uma interligação simbólica entre rochas e minerais e as práticas relacio-nadas com a morte. Na linha de Tim Ingold (2000) consideramos, ainda, que a matéria do monumento seria portadora de determinadas propriedades, revelando-se como entidade viva e atuante na construção de sentidos e memórias associadas ao mundo dos mortos.Fundação para a Ciência e a Tecnologia (FCT

Diffraction and an infrared finite gluon propagator

We discuss some phenomenological applications of an infrared finite gluon propagator characterized by a dynamically generated gluon mass. In particular we compute the effect of the dynamical gluon mass on $pp$ and ${\bar{p}}p$ diffractive scattering. We also show how the data on $\gamma p$ photoproduction and hadronic $\gamma \gamma$ reactions can be derived from the $pp$ and $\bar{p}p$ forward scattering amplitudes by assuming vector meson dominance and the additive quark model.Comment: 4 pages, 7 figures, added references and figures, changed structure. Contribution to Proceedings of XVIIIth Reuniao de Trabalho sobre Interacoes Hadronicas, Sao Paulo, Brazil, 22-24 May, 200

Lattice Simulation of Nuclear Multifragmentation

Motivated by the decade-long debate over the issue of criticality supposedly observed in nuclear multifragmentation, we propose a dynamical lattice model to simulate the phenomenon. Its Ising Hamiltonian mimics a short range attractive interaction which competes with a thermal-like dissipative process. The results here presented, generated through an event-by-event analysis, are in agreement with both experiment and those produced by a percolative (non-dynamical) model.Comment: 8 pages, 3 figure

Effectiveness of repetitive influenza vaccination against SARS-CoV-2 infection among a cohort of health care workers in Portugal

Vaccination for influenza has been essential over the years to protect the most vulnerable populations. Moreover, it was recently suggested that influenza vaccination might confer some nonspecific immunity to other viruses and be associated with a lower risk for coronavirus disease 2019 (COVID-19) morbidity and mortality. Therefore, we aimed to assess the effectiveness of repetitive influenza vaccination against SARS-CoV-2 infection in a cohort of health care workers (HCWs). This study was conducted among HCWs at São João University Hospital Center (CHUSJ), Porto, Portugal, a tertiary reference hospital for diagnosis and therapy, one of the largest hospitals in the country with approximately 6000 HCWs. We analyzed databases for influenza vaccination conducted between 2012 and 2019 and COVID-19 laboratory testing retrieved from the first and last registered positive COVID test date before HCW's COVID-19 vaccination started. The study outcome was the incidence of the first SARS-CoV-2 infection, as determined by reverse transcription polymerase chain reaction (RT-PCR). Age and sex were considered potential confounders. We used multivariable Cox regression to estimate odds ratios. Neither the absolute number nor the proportion of influenza shots influenced the risk of getting infected by SARS-CoV-2 (adjusted odds ratio 1.02, 95% CI: 0.9–1.06 and 1.17 95% CI: 0.86–1.58, respectively). Similar findings were observed in most cases when the analysis was restricted by year. The findings from our retrospective observational analysis of a HCWs cohort failed to support any protective effect between repetitive influenza vaccination and SARS-CoV-2 infection

The Two-Dimensional Analogue of General Relativity

General Relativity in three or more dimensions can be obtained by taking the limit $\omega\rightarrow\infty$ in the Brans-Dicke theory. In two dimensions General Relativity is an unacceptable theory. We show that the two-dimensional closest analogue of General Relativity is a theory that also arises in the limit $\omega\rightarrow\infty$ of the two-dimensional Brans-Dicke theory.Comment: 8 pages, LaTeX, preprint DF/IST-17.9

BLACK HOLES IN THREE-DIMENSIONAL DILATON GRAVITY THEORIES

Three dimensional black holes in a generalized dilaton gravity action theory are analysed. The theory is specified by two fields, the dilaton and the graviton, and two parameters, the cosmological constant and the Brans-Dicke parameter. It contains seven different cases, of which one distinguishes as special cases, string theory, general relativity and a theory equivalent to four dimensional general relativity with one Killing vector. We study the causal structure and geodesic motion of null and timelike particles in the black hole geometries and find the ADM masses of the different solutions.Comment: 19 pages, latex, 4 figures as uuencoded postscript file