Nonlinear dynamical model for the assessment of the seismic behaviour of ferrocement houses

En este trabajo se evalúa el comportamiento cíclico de un prototipo de vivienda de ferrocemento, ensamblado mediante muros prefabricados de pared delgada, con la finalidad de identificar sus parámetros estructurales y proponer un modelo dinámico no lineal para simular el comportamiento de viviendas bajo movimientos sísmicos. Para ello se construyó un prototipo a escala real 1:1 y se probó bajo carga cíclica. De los resultados experimentales se obtuvieron: el comportamiento histerético, la rigidez elástica, la resistencia a cortante, la resistencia máxima, la ductilidad, la capacidad de disipación de energía, el amortiguamiento y el coeficiente de capacidad de disipación de energía; todos ellos, parámetros necesarios para la evaluación dinámica de la vivienda de ferrocemento bajo movimientos sísmicos. Al final se implementó el modelo dinámico no lineal de Bouc-Wen-Baber-Noori (BWBN). Este modelo permitió realizar la evaluación sísmica de la vivienda prefabricada de ferrocemento bajo sismos ocurridos.This article evaluates the cyclic behaviour of a prototype of a precast ferrocement house, which is assembled using precast thin walls, in order to identify its structural parameters and propose a nonlinear dynamical model which is able to simulate the behaviour of those houses when subjected to seismic loading. For this purpose, a full-scale precast ferrocement house was tested under cyclic loading conditions. From the experimental results, the hysteretic behaviour, the elastic stiffness, the shear resistance, the maximum strength, the ductility, the energy dissipation, the equivalent damping and its coefficient of energy dissipation were assessed; those parameters are needed in order to evaluate the dynamic behaviour of ferrocement dwellings when subjected to earthquakes. At the end, the Bouc-Wen-Baber-Noori (BWBN) model of hysteresis was implemented. The model allowed performing the seismic evaluation of the precast ferrocement house under seismic activity.Peer Reviewe

Pharmacokinetic–pharmacodynamic modelling of the analgesic effects of lumiracoxib, a selective inhibitor of cyclooxygenase-2, in rats

Background and purpose: This study establishes a pharmacokinetic/pharmacodynamic (PK/PD) model to describe the time course and in vivo mechanisms of action of the antinociceptive effects of lumiracoxib, evaluated by the thermal hyperalgesia test in rats. Experimental approach: Female Wistar fasted rats were injected s.c. with saline or carrageenan in the right hind paw, followed by either 0, 1, 3, 10 or 30 mg·kg-1 of oral lumiracoxib at the time of carrageenan injection (experiment I), or 0, 10 or 30 mg·kg-1 oral lumiracoxib at 4 h after carrageenan injection (experiment II). Antihyperalgesic responses were measured as latency time (LT) to a thermal stimulus. PK/PD modelling of the antinociceptive response was performed using the population approach with NONMEM VI. Results: A two-compartment model described the plasma disposition. A first-order model, including lag time and decreased relative bioavailability as a function of the dose, described the absorption process. The response model was: LT = LT0/(1 + MED). LT0 is the baseline response, and MED represents the level of inflammatory mediators. The time course of MED was assumed to be equivalent to the predicted profile of COX-2 activity and was modelled according to an indirect response model with a time variant synthesis rate. Drug effects were described as a reversible inhibition of the COX-2 activity. The in vivo estimate of the dissociation equilibrium constant of the COX-2-lumiracoxib complex was 0.24 mg·mL-1. Conclusions: The model developed appropriately described the time course of pharmacological responses to lumiracoxib, in terms of its mechanism of action and pharmacokinetics

Detection of apoptotic events, using different methods, in renal tissues after acute haemorrhage.

Apoptosis plays an important role in cellular damage caused by acute renal hypoperfusion. The aim of this study was to detect apoptotic events in an animal model of acute haemorrhage, followed by volume replacement with different intravenous solution

Manejo de los pacientes con insuficiencia cardiaca atendidos en la consulta de cardiología : Estudio IC-BERG

To determine the perception and management of heart failure with reduced ejection fraction (HFrEF) by clinical cardiologists and to establish a consensus with recommendations. We employed the modified Delphi method among a panel of 150 experts who answered a questionnaire that included three blocks: definition and perception of patients with «stable» HFrEF (15 statements), management of patients with «stable» HFrEF (51 statements) and recommendations for optimising the management and follow-up (9 statements). The level of agreement was assessed with a Likert 9-point scale. A consensus of agreement was reached on 49 statements, a consensus of disagreement was reached on 16, and 10 statements remained undetermined. There was consensus regarding the definition of «stable» HF (82%), that HFrEF had a silent nature that could increase the mortality risk for mildly symptomatic patients (96%) and that the drug treatment should be optimised, regardless of whether a patient with HFrEF remains stable in the same functional class (98.7%). In contrast, there was a consensus of disagreement regarding the notion that treatment with an angiotensin receptor-neprilysin inhibitor is justified only when the functional class worsens (90.7%). Our current understanding of «stable» HF is insufficient, and the treatment needs to be optimised, even for apparently stable patients, to decrease the risk of disease progression

Topological Defects as Seeds for Eternal Inflation

We investigate the global structure of inflationary universe both by analytical methods and by computer simulations of stochastic processes in the early Universe. We show that the global structure of the universe depends crucially on the mechanism of inflation. In the simplest models of chaotic inflation the Universe looks like a sea of thermalized phase surrounding permanently self-reproducing inflationary domains. In the theories where inflation occurs near a local extremum of the effective potential corresponding to a metastable state, the Universe looks like de Sitter space surrounding islands of thermalized phase. A similar picture appears even if the state $\phi = 0$ is unstable but the effective potential has a discrete symmetry $\phi \to =-\phi$. In this case the Universe becomes divided into domains containing different phases. These domains will be separated from each other by domain walls. However, unlike ordinary domain walls, these domain walls will inflate, and their thickness will exponentially grow. In the theories with continuous symmetries inflation generates exponentially expanding strings and monopoles surrounded by thermalized phase. Inflating topological defects will be stable, and they will unceasingly produce new inflating topological defects. This means that topological defects may play a role of indestructible seeds for eternal inflation.Comment: 21 pages, 17 figures (not included), Stanford University preprint SU--ITP--94--

Aplicação das técnicas de deteção de apoptose em ensaios clínicos

A aplicação de metodologias capazes de identificar células apoptóticas constitui uma valiosa ferramenta em vários estudos biomédicos. A hemorragia grave continua a ser a principal causa de morbilidade e mortalidade em animais de companhia vítimas de trauma, situação também comum em humanos, sobretudo jovens vítimas de acidentes de viação. A reperfusão é fundamental, nestas situações, para fomentar a redistribuição do fluxo sanguíneo, repor a disponibilidade de oxigénio e retomar a síntese de ATP, para reconstruir as reservas de energia perdidas e prevenir a morte celular, incluindo a apoptose. Este estudo tem como objectivo principal avaliar os niveis de apoptose no intestino delgado e rim, num ensaio clínico que reproduz a situação de hemorragia pós-trauma, comparando a reperfusão feita com hidroxietilamido 130/0,4 (HES), um coloide, e o Lactato de Ringer (LR), um cristaloide. Dezoito porcos da raça Large White foram submetidos a anestesia total intravenosa (TIVA) com propofol e remifentanil. Nos grupos 1 e 2, os animais foram submetidos a hemorragia controlada e a reposição de volume foi feita usando solução de LR no grupo 1 e HES 130/0.4 no grupo 2. O grupo 3 (grupo controlo), foi apenas submetido a TIVA, sem nenhum outro procedimento. Uma hora após a reposição do volume, os animais foram eutanasiados

Active Brownian Particles. From Individual to Collective Stochastic Dynamics

We review theoretical models of individual motility as well as collective dynamics and pattern formation of active particles. We focus on simple models of active dynamics with a particular emphasis on nonlinear and stochastic dynamics of such self-propelled entities in the framework of statistical mechanics. Examples of such active units in complex physico-chemical and biological systems are chemically powered nano-rods, localized patterns in reaction-diffusion system, motile cells or macroscopic animals. Based on the description of individual motion of point-like active particles by stochastic differential equations, we discuss different velocity-dependent friction functions, the impact of various types of fluctuations and calculate characteristic observables such as stationary velocity distributions or diffusion coefficients. Finally, we consider not only the free and confined individual active dynamics but also different types of interaction between active particles. The resulting collective dynamical behavior of large assemblies and aggregates of active units is discussed and an overview over some recent results on spatiotemporal pattern formation in such systems is given.Comment: 161 pages, Review, Eur Phys J Special-Topics, accepte

Strange particle production in proton-proton collisions at s=0.9\sqrt{s}=0.9 TeV with ALICE at the LHC

The production of mesons containing strange quarks (K$^0_s$, $\phi$) and both singly and doubly strange baryons ($\Lambda$, Anti-$\Lambda$, and $\Xi$+Anti-$\Xi$) are measured at central rapidity in pp collisions at $\sqrt{s}$ = 0.9 TeV with the ALICE experiment at the LHC. The results are obtained from the analysis of about 250 k minimum bias events recorded in 2009. Measurements of yields (dN/dy) and transverse momentum spectra at central rapidities for inelastic pp collisions are presented. For mesons, we report yields () of 0.184 $\pm$ 0.002 stat. $\pm$ 0.006 syst. for K$^0_s$ and 0.021 $\pm$ 0.004 stat. $\pm$ 0.003 syst. for $\phi$. For baryons, we find = 0.048 $\pm$ 0.001 stat. $\pm$ 0.004 syst. for $\Lambda$, 0.047 $\pm$ 0.002 stat. $\pm$ 0.005 syst. for Anti-$\Lambda$ and 0.0101 $\pm$ 0.0020 stat. $\pm$ 0.0009 syst. for $\Xi$+Anti-$\Xi$. The results are also compared with predictions for identified particle spectra from QCD-inspired models and provide a baseline for comparisons with both future pp measurements at higher energies and heavy-ion collisions.Comment: 33 pages, 21 captioned figures, 10 tables, authors from page 28, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/387

Centrality dependence of charged particle production at large transverse momentum in Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm{NN}}} = 2.76 TeV

The inclusive transverse momentum ($p_{\rm T}$) distributions of primary charged particles are measured in the pseudo-rapidity range $|\eta|<0.8$ as a function of event centrality in Pb-Pb collisions at $\sqrt{s_{\rm{NN}}}=2.76$ TeV with ALICE at the LHC. The data are presented in the $p_{\rm T}$ range $0.15<p_{\rm T}<50$ GeV/$c$ for nine centrality intervals from 70-80% to 0-5%. The Pb-Pb spectra are presented in terms of the nuclear modification factor $R_{\rm{AA}}$ using a pp reference spectrum measured at the same collision energy. We observe that the suppression of high-$p_{\rm T}$ particles strongly depends on event centrality. In central collisions (0-5%) the yield is most suppressed with $R_{\rm{AA}}\approx0.13$ at $p_{\rm T}=6$-7 GeV/$c$. Above $p_{\rm T}=7$ GeV/$c$, there is a significant rise in the nuclear modification factor, which reaches $R_{\rm{AA}} \approx0.4$ for $p_{\rm T}>30$ GeV/$c$. In peripheral collisions (70-80%), the suppression is weaker with $R_{\rm{AA}} \approx 0.7$ almost independently of $p_{\rm T}$. The measured nuclear modification factors are compared to other measurements and model calculations.Comment: 17 pages, 4 captioned figures, 2 tables, authors from page 12, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/284