Entropy bounds in terms of the w parameter

In a pair of recent articles [PRL 105 (2010) 041302 - arXiv:1005.1132; JHEP 1103 (2011) 056 - arXiv:1012.2867] two of the current authors have developed an entropy bound for equilibrium uncollapsed matter using only classical general relativity, basic thermodynamics, and the Unruh effect. An odd feature of that bound, S <= A/2, was that the proportionality constant, 1/2, was weaker than that expected from black hole thermodynamics, 1/4. In the current article we strengthen the previous results by obtaining a bound involving the (suitably averaged) w parameter. Simple causality arguments restrict this averaged parameter to be <= 1. When equality holds, the entropy bound saturates at the value expected based on black hole thermodynamics. We also add some clarifying comments regarding the (net) positivity of the chemical potential. Overall, we find that even in the absence of any black hole region, we can nevertheless get arbitrarily close to the Bekenstein entropy.Comment: V1: 14 pages. V2: One reference added. V3: This version accepted for publication in JHE

Comparação do equilíbrio postural entre adolescentes do sexo feminino e masculino

A adolescência compreende a fase entre os 10 e 19 anos de idade, a qual se caracteriza por uma aceleração no crescimento e desenvolvimento dos indivíduos. No entanto, essas mudanças não ocorrem no mesmo ritmo para ambos os sexos, o que pode trazer diferenças no equilíbrio postural. Este estudo tem como objetivo comparar o equilíbrio postural entre adolescentes dos sexos masculino e feminino. O grupo de estudo foi composto por 11 adolescentes do sexo feminino e 19 do sexo masculino. A análise da altura do centro de gravidade foi obtida com o uso de uma prancha de reação, e o equilíbrio postural por meio de uma plataforma de força Advanced Mechanical Technologies, Inc. modelo OR6-6. As variáveis avaliadas foram calculadas a partir do Centro de Pressão (COP): amplitude de deslocamento ântero-posterior do COP (COPap), amplitude de deslocamento médio-lateral do COP (COPml) e velocidade média de deslocamento do COP (COPvel). Os adolescentes do sexo feminino apresentaram amplitude de deslocamento do COPap (p=0,011) e COPml (p=0,003) significativamente menor na condição de olhos abertos que o sexo masculino, e na condição de olhos fechados nas três variáveis avaliadas, COPap (p=0,001), COPml (p=0,001) e COPvel p=0,004, sugerindo menor oscilação postural para as adolescentes deste estudo. Acredita-se que os resultados encontrados podem ser advindos das diferenças nas características antropométricas entre os sexos. Conclui-se que os adolescentes do sexo feminino apresentaram melhor equilíbrio postural quando comparados aos do sexo masculino

The Roosevelt – Rondon expedition marmoset (Mico marcai) : unveiling the conservation status of a data deficient species

The Roosevelt-Rondon Expedition marmoset, Mico marcai, was collected in 1914 and to date, all information on this species comes from three skins brought back by the Expedition and two additional skins collected in the 1990s. It is no surprise then that M.marcai has been classified as Data Deficient (DD). Given that Mico marcai’s suspected range sits on the path of the advancing Brazilian “Arc-of-Deforestation”, it is urgent that relevant data be collected to assess this taxon. Here we present the first comprehensive field data on the distribution, population size and threats on M. marcai with the goal of removing the species from the DD category. From 2012 to 2015, we surveyed for the species in 11 localities, in and around the Marmelos-Aripuanã interfluve, and estimated density using distance sampling on 10 transects. We also used spatial predictive modelling to project the amount of habitat that will be lost within its range in 18 years under different deforestation scenarios. We found marmosets in 14 localities and calculated its Extent of Occurrence to be 31,073 km2. We walked 271 km and detected 30 marmoset groups, allowing us to estimate their density to be 8.31 individuals/km2 and a total population of 258,217.71 individuals. By a “Business as usual” scenario, 20,181 km2 of habitat will be lost in three marmoset generations (~18 years), compromising 33% of the species’ range. Accordingly, M. marcai should be classified as globally Vulnerable under category A3c. Following our study, we propose the Amazonian marmosets, genus Mico, should undergo similar re-assessment as their ranges all fall in the path of the Arc-of-Deforestation. Keywords: Amazonian marmosets, Conservation Status, Data Deficient, Habitat Loss, Southern Amazoni

Severe hereditary spherocytosis and distal renal tubular acidosis associated with the total absence of band 3

Absence of band 3, associated with the mutation Coimbra (V488M) in the homozygous state, caused severe hereditary spherocytosis in a young child. Although prenatal testing was made available to the parents, it was declined. Because the fetus stopped moving near term, an emergency cesarean section was performed and a severely anemic, hydropic female baby was delivered. She was resuscitated and initially kept alive with respiratory assistance and hypertransfusion therapy. Cord blood smears revealed erythroblastosis, poikilocytosis, and red cells with stalk-like elongations. Band 3 and protein 4.2 were absent; spectrin, ankyrin, and glycophorin A were significantly reduced. Renal tubular acidosis was detected by the age of 3 months. Nephrocalcinosis appeared soon thereafter. After 3 years of follow-up the child is doing reasonably well on a regimen that includes regular blood transfusions and daily bicarbonate supplements. The long-term prognosis remains uncertain given the potential for hematologic and renal complications

Pathologies in Asymptotically Lifshitz Spacetimes

There has been significant interest in the last several years in studying possible gravitational duals, known as Lifshitz spacetimes, to anisotropically scaling field theories by adding matter to distort the asymptotics of an AdS spacetime. We point out that putative ground state for the most heavily studied example of such a spacetime, that with a flat spatial section, suffers from a naked singularity and further point out this singularity is not resolvable by any known stringy effect. We review the reasons one might worry that asymptotically Lifshitz spacetimes are unstable and employ the initial data problem to study the stability of such systems. Rather surprisingly this question, and even the initial value problem itself, for these spacetimes turns out to generically not be well-posed. A generic normalizable state will evolve in such a way to violate Lifshitz asymptotics in finite time. Conversely, enforcing the desired asymptotics at all times puts strong restrictions not just on the metric and fields in the asymptotic region but in the deep interior as well. Generically, even perturbations of the matter field of compact support are not compatible with the desired asymptotics.Comment: 36 pages, 1 figure, v2: Enhanced discussion of singularity, including relationship to Gubser's conjecture and singularity in RG flow solution, plus minor clarification

Numerical modeling of the tension stiffening in reinforced concrete members via discontinuum models

[prova tipográfica]This study presents a numerical investigation on the fracture mechanism of tension stiffening phenomenon in reinforced concrete members. A novel approach using the discrete element method (DEM) is proposed, where three-dimensional randomly generated distinct polyhedral blocks are used, representing concrete and one-dimensional truss elements are utilized, representing steel reinforcements. Thus, an explicit representation of reinforced concrete members is achieved, and the mechanical behavior of the system is solved by integrating the equations of motion for each block using the central difference algorithm. The inter-block interactions are taken into consideration at each contact point with springs and cohesive frictional elements. Once the applied modeling strategy is validated, based on previously published experimental findings, a sensitivity analysis is performed for bond stiffness, cohesion strength, and the number of truss elements. Hence, valuable inferences are made regarding discontinuum analysis of reinforced concrete members, including concrete-steel interaction and their macro behavior. The results demonstrate that the proposed phenomenological modeling strategy successfully captures the concrete-steel interaction and provides an accurate estimation of the macro behavior

Potential geographic distribution of Hantavirus reservoirs in Brazil

Hantavirus cardiopulmonary syndrome is an emerging zoonosis in Brazil. Human infections occur via inhalation of aerosolized viral particles from excreta of infected wild rodents. Necromys lasiurus and Oligoryzomys nigripes appear to be the main reservoirs of hantavirus in the Atlantic Forest and Cerrado biomes. We estimated and compared ecological niches of the two rodent species, and analyzed environmental factors influencing their occurrence, to understand the geography of hantavirus transmission. N. lasiurus showed a wide potential distribution in Brazil, in the Cerrado, Caatinga, and Atlantic Forest biomes. Highest climate suitability for O. nigripes was observed along the Brazilian Atlantic coast. Maximum temperature in the warmest months and annual precipitation were the variables that most influence the distributions of N. lasiurus and O. nigripes, respectively. Models based on occurrences of infected rodents estimated a broader area of risk for hantavirus transmission in southeastern and southern Brazil, coinciding with the distribution of human cases of hantavirus cardiopulmonary syndrome. We found no demonstrable environmental differences among occurrence sites for the rodents and for human cases of hantavirus. However, areas of northern and northeastern Brazil are also apparently suitable for the two species, without broad coincidence with human cases. Modeling of niches and distributions of rodent reservoirs indicates potential for transmission of hantavirus across virtually all of Brazil outside the Amazon Basin