Simulation of reproductive risk and emergence of female reproductive cessation

Using a simple computer model for evolution, we show that in a sexual population subject only to age-increasing reproductive risk, a cessation of female reproduction emerges.Comment: 11 pages including 3 figure

Effects of air temperature on physiology and productive performance of pigs during growing and finishing phases

Thirty-six castrated male pigs were used to determine the influence of thermal environment and reduction of consumption on performance and carcass composition. Animals were housed in two climate chambers. In one, animals were in thermal comfort (TN) (22 °C), and in the other, pigs were under heat stress (HS) (34 °C). Animals were distributed in a randomized block design, making three treatments (TN, HS and animals in thermal comfort with food consumption paired with that observed in HS (PFTN)), with six replicates and two animals per experimental unit. Data were obtained on performance and carcass composition. The weight gains of HS and PFTN animals were reduced by 40.5% and 34.7%, respectively, reflecting a reduction of 13.2% in the final weight of PFTN animals. Triiodothyronine concentration was not affected by heat, but there was an increase in lymphocyte numbers in PFTN animals. The HS and PFTN animals showed lower hot carcass weight. However, there were no effects on hot carcass yield and relative weights of heart, lung and spleen. Heat stress compromised performance. The negative effects of high temperature on pigs include reduction in feed intake and changes in physiology.Keywords: Environment, heat stress, pair feed, pig growth, pig productio

Elastase-2, a tissue alternative pathway for angiotensin II generation, plays a role in circulatory sympathovagal balance in mice

In vitro and ex vivo experiments indicate that elastase-2 (ELA-2), a chymotrypsin-serine protease elastase family member 2A, is an alternative pathway for angiotensin II (Ang II) generation. However, the role played by ELA-2 in vivo is unclear. We examined ELA-2 knockout (ELA-2KO) mice compared to wild-type (WT) mice and determined whether ELA-2 played a role in hemodynamics [arterial pressure (AP) and heart rate (HR)], cardiocirculatory sympathovagal balance and baroreflex sensitivity. The variability of systolic arterial pressure (SAP) and pulse interval (PI) for evaluating autonomic modulation was examined for time and frequency domains (spectral analysis), whereas a symbolic analysis was also used to evaluate PI variability. In addition, baroreflex sensitivity was examined using the sequence method. Cardiac function was evaluated echocardiographically under anesthesia. The AP was normal whereas the HR was reduced in ELA-2KO mice (425 ± 17 vs. 512 ± 13 bpm from WT). SAP variability and baroreflex sensitivity were similar in both strains. The LF power from the PI spectrum (33.6 ± 5 vs. 51.8 ± 4.8 nu from WT) and the LF/HF ratio (0.60 ± 0.1 vs. 1.45 ± 0.3 from WT) were reduced, whereas the HF power was increased (66.4 ± 5 vs. 48.2 ± 4.8 nu from WT) in ELA-2KO mice, indicating a shift toward parasympathetic modulation of HR. Echocardiographic examination showed normal fractional shortening and an ejection fraction in ELA-2KO mice; however, the cardiac output, stroke volume, and ventricular size were reduced. These findings provide the first evidence that ELA-2 acts on the sympathovagal balance of the heart, as expressed by the reduced sympathetic modulation of HR in ELA-2KO mice

Prevalence and risk factors for bovine leptospirosis in Mato Grosso do Sul, Brazil

Foi investigada a prevalência de anticorpos antileptospira em fêmeas bovinas com idade igual ou superior a 24 meses, provenientes de 178 rebanhos de 22 municípios do estado de Mato Grosso do Sul, bem como identificados fatores de risco associados à infecção. Foram analisadas 2.573 amostras de soro sangüíneo por meio do teste de soroaglutinação microscópica perante 10 sorovares de leptospira. Títulos iguais ou superiores a 100 para um ou mais sorovares foram detectados em 1.801 fêmeas (98,8%) de 161 (96,5%) rebanhos. O sorovar Hardjo (65,6%) foi apontado como o mais provável, seguido do sorovar Wolffi (12,3%). Os resultados demonstram que a leptospirose bovina se encontra presente em todos os municípios estudados, com alta prevalência, tanto em animais como em rebanhos. Os fatores de risco identificados neste estudo e associados à infecção por bactérias do gênero lepstopira foram o tipo de exploração pecuária de corte e a raça Zebu. _____________________________________________________________________________________________________________ ABSTRACTThe prevalence of anti-Leptospira spp. antibodies was estimated for female cattle aged 24 months or older. The sample comprised 178 herds from 22 counties in the state of Mato Grosso do Sul, Brazil. The risk factors associated with the presence of infeccion were investigated. A total of 2,573 blood serum samples were tested against 10 leptospira serovars using the microagglutination test (MAT). Titers of 100 or higher for one or more serovars were detected in 1,801 females (98.8%) from 161 herds (96.5%). Serovar Hardjo (65.6%) was the most frequent, followed by serovar Wolffi (12.3%). These results suggest that bovine leptospirosis is widespread in all the counties under study, with a high prevalence both at the animal and the herd level. Beef farms and the Zebu breed were associated to the higher risk of herd infection by leptospiras

Decomposition and nutrient release of leguminous plants in coffee agroforestry systems.

Leguminous plants used as green manure are an important nutrient source for coffee plantations, especially for soils with low nutrient levels. Field experiments were conducted in the Zona da Mata of Minas Gerais State, Brazil to evaluate the decomposition and nutrient release rates of four leguminous species used as green manures (Arachis pintoi, Calopogonium mucunoides, Stizolobium aterrimum and Stylosanthes guianensis) in a coffee agroforestry system under two different climate conditions. The initial N contents in plant residues varied from 25.7 to 37.0 g kg-1 and P from 2.4 to 3.0 g kg-1. The lignin/N, lignin/polyphenol and(lignin+polyphenol)/N ratios were low in all residues studied. Mass loss rates were highest in the first 15 days, when 25 % of the residues were decomposed. From 15 to 30 days, the decomposition rate decreased on both farms. On the farm in Pedra Dourada (PD), the decomposition constant k increased in the order C. mucunoides < S. aterrimum < S. guianensis < A. pintoi. On the farm in Araponga (ARA), there was no difference in the decomposition rate among leguminous plants. The N release rates varied from 0.0036 to 0.0096 d-1. Around 32 % of the total N content in the plant material was released in the first 15 days. In ARA, the N concentration in the S. aterrimum residues was always significantly higher than in the other residues. At the end of 360 days, the N released was 78 % in ARA and 89 % in PD of the initial content. Phosphorus was the most rapidly released nutrient (k values from 0.0165 to 0.0394 d-1). Residue decomposition and nutrient release did not correlate with initial residue chemistry and biochemistry, but differences in climatic conditions between the two study sites modified the decomposition rate constants

Solar radiation and vertical leaf area distribution in forest - Reserva Biológica do Cueiras ZF02, Manaus

In this work, the vertical leaf area distribution is investigated in connection with radiation regime, using the measurements of solar radiation made om July to November 2001 at the experimental site of Reserva Biológica do Cuieiras, Manaus, ZF2 km 14 and km 34, in Central Amazonia. A sampling technique is used for the radiation measurements inside two tall canopy covers, having a mobile support apparatus, made up of modular ame, which allows placement of the radiation sensors at different heights along a vertical line within the canopy. Inversion of the solar radiation physical model allowed a determination of the leaf area density. Spatial variability of leaf area (LAI, function a(z)) is established for the two experimental sites om the measurements of solar radiation in three verticals on each site. The average values of leaf area index (LAI) for the local vegetation at km 14 and at km 34 ZF2 were 6,4 and 6,1, respectively. A comparative analysis is developed concerning the vertical distributions of leaf area obtained for different experimental sites in Amazonia, using the same solar radiation measurement system.Neste estudo, a distribuição vertical de área foliar em floresta é investigada em conexão com o regime de radiação, usando as medidas de radiação solar realizadas no período de julho a novembro de 2001, na Reserva Biológica do Cuieiras - Manaus ZF2, km 14 e km 34, na Amazônia Central. Técnicas experimentais de amostragem de radiação no interior de coberturas vegetais de grande porte são utilizadas, com dispositivos de suporte móveis constituídos por reticulados modulares, que permitem a disposição dos sensores de radiação em diferentes níveis de uma mesma vertical no interior da cobertura. Inversão de modelos radiativos em coberturas vegetais densas permite as análises sobre a distribuição vertical de área foliar. A variabilidade espacial de área foliar (IAF, função a(z)) é estabelecida para os dois sítios experimentais a partir de medidas de radiação solar, individualizadas em três verticais em cada um desses locais. O índice de área foliar total médio (IAF) da vegetação local para o sítio experimental do km 14 alcançou o valor de 6,4 e para o sítio experimental do km 34 o valor de 6,1. Uma análise comparativa é desenvolvida sobre distribuições verticais de área foliar obtidas em sítios experimentais da Amazônia, usando o mesmo sistema de medidas de radiação solar

Fibre reinforced mortar application for out-of-plane strengthening of schist walls

The aim of the present work is to assess the effectiveness of an innovative strengthening technique for the rehabilitation of masonry buildings deficiently prepared to resist to loading conditions typical of seismic events. This technique is based on the application of outer layers of fibre reinforced mortar (FRM) by spray technology and it is used for increasing the load carrying capacity and deformation ability of masonry elements. For this purpose three almost real scale schist walls prototypes were strengthened and tested. The experimental program is described and the relevant results are presented and discussed. For estimating the properties of the schist walls and FRM taking into account the application conditions, the tested prototypes were simulated with a FEM-based computer program that has constitutive models for the simulation of the nonlinear behaviour of these materials. By using the derived properties, a parametric study was conducted to identify the influence of the FRM properties on the performance of the proposed strengthening system.The author wish to acknowledge CiviTest, Lda (Jesufrei, Portugal) for supporting the experimental program, the sustain provided by INOTEC - Innovative material of ultra-high ductility for the rehabilitation of the built patrimony, QREN project number 23024, and the collaboration of the companies Owens Corning, Exporplas, Sika, Chryso and SECIL for providing, respectively, glass fibres, polypropylene fibres, superplasticizers, Viscous Modifier Agent, and Cement. The authors further wish to acknowledge the Erasmus Plus and Placement Mobility Programs among the University of Ferrara (Italy), the University of Minho (Portugal) and the CiviTest Lda (Portugal) which made this international cooperation possible

Fine-Tuning Solution for Hybrid Inflation in Dissipative Chaotic Dynamics

We study the presence of chaotic behavior in phase space in the pre-inflationary stage of hybrid inflation models. This is closely related to the problem of initial conditions associated to these inflationary type of models. We then show how an expected dissipative dynamics of fields just before the onset of inflation can solve or ease considerably the problem of initial conditions, driving naturally the system towards inflation. The chaotic behavior of the corresponding dynamical system is studied by the computation of the fractal dimension of the boundary, in phase space, separating inflationary from non-inflationary trajectories. The fractal dimension for this boundary is determined as a function of the dissipation coefficients appearing in the effective equations of motion for the fields.Comment: 10 pages, 4 eps figures (uses epsf), Revtex. Replaced with version to match one in press Physical Review

Sensor based on β - NiOx hybrid film/multi-walled carbon nanotubes composite electrode for groundwater salinization inspection

The enrichment of groundwater with different nutrients (Na+, Ca2+, Mg2+, Cl−, CO32−, among others) triggers the salinization of the aquifer and makes it inappropriate for many purposes. In this work, we developed a highly sensitive and selective electrochemical sensor, based on Ni-inorganic films electrosynthetized in situ onto multi-walled carbon nanotubes composite paste electrode (MWCNE), which allows the early detection of salinization. The working sensor (β-NiOx/MWCNE) was derivatized from nickel hexacyanoferrate modified electrode in strong alkaline medium (pH = 12), producing a hybrid film composed by β-Ni(OH)2 and β-NiO(OH). The electrochemical properties, morphology and chemical composition of the formed β-NiOx thin films were evaluated by voltammetry, scanning electron microscopy and X-ray spectroscopy. The developed β-NiOx/MWCNE sensor was highly sensitive to the presence of Na+ cation by ion-exchange, and the increase of Na+ concentration in the range 4.46 × 10−7 to 4.93 × 10−6 mol L−1 inhibited linearly the reversible electrochemical signal of the device, allowing to determine trace concentrations of this ion (LOD = 9.86 × 10−8 mol L−1) with high correlation coefficient of the data (r = 0.999) and suitable precision/reproducibility of the measurements (RSD < 9%). Using Na+ as salinization marker and β-NiOx/MWCNE as electroanalytical device, we found evidences of groundwater salinization in Grossos, a Brazil coast city, whose inhabitants have hypertension above the national average. The attained results were comparable to those obtained by the standard methods for Na+ analysis (percentage error ranging from 0.5 to 1.6%), confirming the accuracy of the proposed electroanalytical platform.info:eu-repo/semantics/publishedVersio