No Heavy Element Dispersion in the Globular Cluster M92

Although there have been recent claims that there is a large dispersion in the abundances of the heavy neutron capture elements in the old Galactic globular cluster M92, we show that the measured dispersion for the absolute abundances of four of the rare earth elements within a sample of 12 luminous red giants in M92 (less than or equal to 0.07 dex) does not exceed the relevant sources of uncertainty. As expected from previous studies, the heavy elements show the signature of the r-process. Their abundance ratios are essentially identical to those of M30, another nearby globular cluster of similar metallicity.Comment: Accepted for publication in ApJ Letter

Comparative evaluation of therapeutic interventions during hemorrhagic shock

Trabalho apresentado ao 31º International Symposium on Intensive Care and Emergency Medicine, 2011, Bruxelas

Constitutive relations for compressible granular flow in the inertial regime

Granular flows occur in a wide range of situations of practical interest to industry, in our natural environment and in our everyday lives. This paper focuses on granular flow in the so-called inertial regime, when the rheology is independent of the very large particle stiffness. Such flows have been modelled with the μ(I),Φ(I)-rheology, which postulates that the bulk friction coefficient μ (i.e. the ratio of the shear stress to the pressure) and the solids volume fraction ϕ are functions of the inertial number I only. Although the μ(I),Φ(I)-rheology has been validated in steady state against both experiments and discrete particle simulations in several different geometries, it has recently been shown that this theory is mathematically ill-posed in time-dependent problems. As a direct result, computations using this rheology may blow up exponentially, with a growth rate that tends to infinity as the discretization length tends to zero, as explicitly demonstrated in this paper for the first time. Such catastrophic instability due to ill-posedness is a common issue when developing new mathematical models and implies that either some important physics is missing or the model has not been properly formulated. In this paper an alternative to the μ(I),Φ(I)-rheology that does not suffer from such defects is proposed. In the framework of compressible I-dependent rheology (CIDR), new constitutive laws for the inertial regime are introduced; these match the well-established μ(I) and Φ(I) relations in the steady-state limit and at the same time are well-posed for all deformations and all packing densities. Time-dependent numerical solutions of the resultant equations are performed to demonstrate that the new inertial CIDR model leads to numerical convergence towards physically realistic solutions that are supported by discrete element method simulations

Close phylogenetic relationship between Angolan and Romanian HIV-1 subtype F1 isolates

<p>Abstract</p> <p>Background</p> <p>Here, we investigated the phylogenetic relationships of the HIV-1 subtype F1 circulating in Angola with subtype F1 strains sampled worldwide and reconstructed the evolutionary history of this subtype in Central Africa.</p> <p>Methods</p> <p>Forty-six HIV-1-positive samples were collected in Angola in 2006 and subtyped at the <it>env</it>-gp41 region. Partial <it>env</it>-gp120 and <it>pol-RT </it>sequences and near full-length genomes from those <it>env</it>-gp41 subtype F1 samples were further generated. Phylogenetic analyses of partial and full-length subtype F1 strains isolated worldwide were carried out. The onset date of the subtype F1 epidemic in Central Africa was estimated using a Bayesian Markov chain Monte Carlo approach.</p> <p>Results</p> <p>Nine Angolan samples were classified as subtype F1 based on the analysis of the <it>env</it>-gp41 region. All nine Angolan sequences were also classified as subtype F1 in both <it>env-gp120 </it>and <it>pol-RT </it>genomic regions, and near full-length genome analysis of four of these samples confirmed their classification as "pure" subtype F1. Phylogenetic analyses of subtype F1 strains isolated worldwide revealed that isolates from the Democratic Republic of Congo (DRC) were the earliest branching lineages within the subtype F1 phylogeny. Most strains from Angola segregated in a monophyletic group together with Romanian sequences; whereas South American F1 sequences emerged as an independent cluster. The origin of the subtype F1 epidemic in Central African was estimated at 1958 (1934–1971).</p> <p>Conclusion</p> <p>"Pure" subtype F1 strains are common in Angola and seem to be the result of a single founder event. Subtype F1 sequences from Angola are closely related to those described in Romania, and only distantly related to the subtype F1 lineage circulating in South America. Original diversification of subtype F1 probably occurred within the DRC around the late 1950s.</p

Effects of terlipressin as early treatment for protection of brain in a model of haemorrhagic shock

Introduction: We investigated whether treatment with terlipressin during recovery from hypotension due to haemorrhagic shock (HS) is effective in restoring cerebral perfusion pressure (CPP) and brain tissue markers of water balance, oxidative stress and apoptosis. Methods: In this randomised controlled study, animals undergoing HS (target mean arterial pressure (MAP) 40 mmHg for 30 minutes) were randomised to receive lactated Ringer’s solution (LR group; n =14; volume equal to three times the volume bled), terlipressin (TERLI group; n =14; 2-mg bolus), no treatment (HAEMO group; n =12) or sham (n =6). CPP, systemic haemodynamics (thermodilution technique) and blood gas analyses were registered at baseline, shock and 5, 30, 60 (T60), 90 and 120 minutes after treatment (T120). After the animals were killed, brain tissue samples were obtained to measure markers of water balance (aquaporin-4 (AQP4)), Na+-K+-2Cl− co-transporter (NKCC1)), oxidative stress (thiobarbituric acid reactive substances (TBARS) and manganese superoxide dismutase (MnSOD)) and apoptotic damage (Bcl-x and Bax). Results: Despite the HS-induced decrease in cardiac output (CO) and hyperlactataemia, resuscitation with terlipressin recovered MAP and resulted in restoration of CPP and in cerebral protection expressed by normalisation of AQP4, NKCC1, TBARS and MnSOD expression and Bcl-x/Bax ratio at T60 and T120 compared with sham animals. In the LR group, CO and blood lactate levels were recovered, but the CPP and MAP were significantly decreased and TBARS levels and AQP4, NKCC1 and MnSOD expression and Bcl-x/Bax ratio were significantly increased at T60 and T120 compared with the sham group. Conclusions: During recovery from HS-induced hypotension, terlipressin was effective in normalising CPP and cerebral markers of water balance, oxidative damage and apoptosis. The role of this pressor agent on brain perfusion in HS requires further investigation