Phantom Accretion by Black Holes and the Generalized Second Law of Thermodynamics

The accretion of a phantom fluid with non-zero chemical potential by black holes is discussed with basis on the Generalized Second Law of thermodynamics. For phantom fluids with positive temperature and negative chemical potential we demonstrate that the accretion process is possible, and that the condition guaranteeing the positiveness of the phantom fluid entropy coincides with the one required by Generalized Second Law. In particular, this result provides a complementary confirmation that cosmological phantom fluids do not need to have negative temperatures

Realistic fluids as source for dynamically accreting black holes in a cosmological background

We show that a single imperfect fluid can be used as a source to obtain the generalized McVittie metric as an exact solution to Einstein's equations. The mass parameter in this metric varies with time thanks to a mechanism based on the presence of a temperature gradient. This fully dynamical solution is interpreted as an accreting black hole in an expanding universe if the metric asymptotes to Schwarzschild-de Sitter at temporal infinity. We present a simple but instructive example for the mass function and briefly discuss the structure of the apparent horizons and the past singularity.Comment: 5 pages, 2 figures. Updated references and minor changes to match the version accepted for publishing in PR

Analytical solutions of accreting black holes immersed in a Lambda-CDM model

The evolution of the mass of a black hole embedded in a universe filled with dark energy and cold dark matter is calculated in a closed form within a test fluid model in a Schwarzschild metric, taking into account the cosmological evolution of both fluids. The result describes exactly how accretion asymptotically switches from the matter-dominated to the Lambda-dominated regime. For early epochs, the black hole mass increases due to dark matter accretion, and on later epochs the increase in mass stops as dark energy accretion takes over. Thus, the unphysical behaviour of previous analyses is improved in this simple exact model.Comment: 8 pages, 1 figure, accepted for publication in Physics Letters

Exhaustive CoMFA and CoMSIA analyses around different chemical entities: a ligand-based study exploring the affinity and selectivity profiles of 5-HT1A ligands

The 5-hydroxytryptamine (5-HT1A) receptors represent an attractive target in drug discovery. In particular, 5-HT1A agonists and partial agonists are deeply investigated for their potential role in the treatment of anxiety, depression, ischaemic brain disorder and more recently, of pain. On the other hand, 5-HT1A antagonists have been revealed promising compounds in cognition disorders and, lately, in cancer. Thus, the discovery of 5HT1A ligands is nowadays an appealing research activity in medicinal chemistry. In this work, Comparative Molecular Fields Analysis (CoMFA) and Comparative Molecular Similarity Index Analysis (CoMSIA) were applied on an in-house library of 5-HT1A ligands bearing different chemical scaffolds in order to elucidate their affinity and selectivity for the target. Following this procedure, a number of structural modifications have been drawn for the development of much more effective 5-HT1AR ligands

Unified dark energy thermodynamics: varying w and the -1-crossing

We investigate, in a unified and general way, the thermodynamic properties of dark energy with an arbitrary, varying equation-of-state parameter w(a). We find that all quantities are well defined and regular for every w(a), including at the -1-crossing, with the temperature being negative in the phantom regime (w(a)-1). The density and entropy are always positive while the chemical potential can be arbitrary. At the -1-crossing, both temperature and chemical potential are zero. The temperature negativity can only be interpreted in the quantum framework. The regular behavior of all quantities at the -1-crossing, leads to the conclusion that such a crossing does not correspond to a phase transition, but rather to a smooth cross-over.Comment: 5 pages, version published in Class. Quant. Gra

Citocinas séricas na forma crônica da doenca de Chagas

We studied the serum levels of IL-2, IFN-g and TNF in different clinical forms of Chagas' disease and in patients clinically compensated and decompensated. Cytokines measured in 91 patients with the chronic form of the disease did not differ from those of 13 normal individuals, suggesting the absence of activation of the TH1 pattern of lymphocyte response. There were no statistical differences among the 17 patients in the indeterminate form of the disease, the patients presenting either early (n = 4) or well-developed signs of cardiomyopathy (n = 62), the digestive (n = 4) or the mixed (n = 4) forms of the disease. Serum TNF was undetectable and IFN-g levels did not differ between clinical forms and severities of Chagas' disease. However, we found IL-2 higher levels in the 25 non-controlled patients than in the 66 controlled individuals (p < 0,001). We suggest that IL-2 dosage may be useful as an indicator of the need for more aggressive procedures.Estudamos os níveis séricos da IL-2, IFN-g e do TNF-a de portadores da doença de Chagas em suas diferentes formas clínicas, compensados e descompensados. As citocinas medidas nos 91 pacientes com a forma crônica da doença não diferiram dos níveis de 13 indivíduos controle. Não houve diferença estatística entre os 17 portadores da forma indeterminada da doença e os portadores de cardiopatia insipiente (n = 4), de cardiopatia bem estabelecida (n = 62), da forma digestiva (n = 4) ou da forma mista (n = 4) da doença. Os níveis séricos de TNF foram indetectáveis e IFN-g não diferiu nas diferentes formas clínicas ou com a severidade da doença. No entanto, encontramos níveis mais elevados de IL-2 nos 25 pacientes não-contrololados do que nos 66 pacientes bem compensados (p < 0,001). Sugerimos que a dosagem de IL-2 possa servir como indicadora da necessidade de terapêuticas mais agressivas nestes pacientes.28528

Hawking radiation and thermodynamics of dynamical black holes in phantom dominated universe

The thermodynamic properties of dark energy-dominated universe in the presence of a black hole are investigated in the general case of a varying equation-of-state-parameter $w(a)$. We show that all the thermodynamics quantities are regular at the phantom divide crossing, and particularly the temperature and the entropy of the dark fluid are always positive definite. We also study the accretion process of a phantom fluid by black holes and the conditions required for the validity of the generalized second law of thermodynamics. As a results we obtain a strictly negative chemical potential and an equation-of-state parameter $w<-5/3.$Comment: 22 pages,3 figure

Brans-Dicke Theory and primordial black holes in Early Matter-Dominated Era

We show that primordial black holes can be formed in the matter-dominated era with gravity described by the Brans-Dicke theory. Considering an early matter-dominated era between inflation and reheating, we found that the primordial black holes formed during that era evaporate at a quicker than those of early radiation-dominated era. Thus, in comparison with latter case, less number of primordial black holes could exist today. Again the constraints on primordial black hole formation tend towards the larger value than their radiation-dominated era counterparts indicating a significant enhancement in the formation of primordial black holes during the matter-dominaed era.Comment: 9 page

Reporting of rehabilitation intervention for low back pain in randomized controlled trials : Is the treatment fully replicable?

Study Design. Methodological review of randomized controlled trials (RCTs). Objective. To assess the quality of reporting of rehabilitation interventions for mechanical low back pain (LBP) in published RCTs. Summary of Background Data. Reporting of interventions in RCTs often focused on the outcome value and failed to describe interventions adequately. Methods. We systematically searched for all RCTs in Cochrane systematic reviews on LBP published in the Cochrane Database of Systematic Reviews until December 2013. The description of rehabilitation interventions of each RCT was evaluated independently by 2 of the investigators, using an ad hoc checklist of 7 items. The primary outcome was the number of items reported in sufficient details to be replicable in a new RCT or in everyday practice. Results. We found 11 systematic reviews, including 220 eligible RCTs, on LBP. Of those, 185 RCTs were included. The median publication year was 1998 (I-III quartiles, 1990 to 2004). The most reported items were the characteristics of participants (91.3%; 95% confidence interval [CI], 87.3-95.4), the intervention providers (81.1%; 95% CI, 75.4-86.7), and the intervention schedule (69.7%; 95% CI, 63-76). Based on the description of the intervention, less than one fifth would be replicable clinically. The proportion of trials providing all essential information about the participants and interventions increased from 14% (n=7) in 1971 to 1980 to 20% (n=75) in 2001 to 2010. Conclusion. Despite the remarkable amount of energy spent producing RCTs in LBP rehabilitation, the majority of RCTs failed to report sufficient information that would allow the intervention to be replicated in clinical practice. Improving the quality of intervention description is urgently needed to better transfer research into rehabilitation practices

Simulating Food Web Dynamics along a Gradient: Quantifying Human Influence

Realistically parameterized and dynamically simulated food-webs are useful tool to explore the importance of the functional diversity of ecosystems, and in particular relations between the dynamics of species and the whole community. We present a stochastic dynamical food web simulation for the Kelian River (Borneo). The food web was constructed for six different locations, arrayed along a gradient of increasing human perturbation (mostly resulting from gold mining activities) along the river. Along the river, the relative importance of grazers, filterers and shredders decreases with increasing disturbance downstream, while predators become more dominant in governing eco-dynamics. Human activity led to increased turbidity and sedimentation which adversely impacts primary productivity. Since the main difference between the study sites was not the composition of the food webs (structure is quite similar) but the strengths of interactions and the abundance of the trophic groups, a dynamical simulation approach seemed to be useful to better explain human influence. In the pristine river (study site 1), when comparing a structural version of our model with the dynamical model we found that structurally central groups such as omnivores and carnivores were not the most important ones dynamically. Instead, primary consumers such as invertebrate grazers and shredders generated a greater dynamical response. Based on the dynamically most important groups, bottom-up control is replaced by the predominant top-down control regime as distance downstream and human disturbance increased. An important finding, potentially explaining the poor structure to dynamics relationship, is that indirect effects are at least as important as direct ones during the simulations. We suggest that our approach and this simulation framework could serve systems-based conservation efforts. Quantitative indicators on the relative importance of trophic groups and the mechanistic modeling of eco-dynamics could greatly contribute to understanding various aspects of functional diversity