2,390 research outputs found

    Genetic diversity of Lusitano horse in Brazil using pedigree information

    Get PDF
    This study aimed to evaluate population parameters and to describe the genetic diversity of the Lusitano breed in Brazil using pedigree data. Two populations were evaluated: total population (TP) containing 18,922 animals, and reference population (RP) composed of a part of TP containing 8,329 animals, representing the last generation. The generation interval (10.1 ± 5.1 years) was in the range for horse populations. Pedigree completeness in RP shows almost 100% filling in the three most recent generations, indicating improvement in the pedigree data and accuracy of the results, and the inbreeding coefficient (4.46%) and average relatedness (5.97%) for RP, indicating control on the part of breeders. The effective population size was 89 (TP) and 90 (RP). The effective number of founders (fe) were 33 and 29, effective number of ancestors (fa) were 30 and 26, and effective number of founder genomes (fg) were 19 and 15 for TP and RP, respectively, indicating a reduction of genetic variability in the last generations. The total number of ancestors that explains 100% of the genetic diversity in the Lusitano breed in Brazil was 427 (TP) and 341 (RP). The reproductive parameters, probabilities of gene origin showing loss of variability in the last generations, and the genetic contributions of ancestors suggest the need to monitor genetic diversity over time in breeding programs to allow control of the next generations and to increase their variability.info:eu-repo/semantics/publishedVersio

    Analysis of the Evans and Baranyai variational principle in dilute gases

    Get PDF
    A variational principle for thermostated nonequilibrium steady states recently proposed by Evans and Baranyai [Phys. Rev. Lett. 67, 2597 (1991)] is analyzed by means of a model kinetic equation for dilute gases. It is shown that the principle does not apply exactly, although deviations from it are small, especially when the gradients are not very largeDirección General de Investigaciones Científicas y Técnicas PB89-0618 y PB91-031

    Third and fourth degree collisional moments for inelastic Maxwell models

    Full text link
    The third and fourth degree collisional moments for dd-dimensional inelastic Maxwell models are exactly evaluated in terms of the velocity moments, with explicit expressions for the associated eigenvalues and cross coefficients as functions of the coefficient of normal restitution. The results are applied to the analysis of the time evolution of the moments (scaled with the thermal speed) in the free cooling problem. It is observed that the characteristic relaxation time toward the homogeneous cooling state decreases as the anisotropy of the corresponding moment increases. In particular, in contrast to what happens in the one-dimensional case, all the anisotropic moments of degree equal to or less than four vanish in the homogeneous cooling state for d2d\geq 2.Comment: 15 pages, 3 figures; v2: addition of two new reference

    Impurity in a granular gas under nonlinear Couette flow

    Full text link
    We study in this work the transport properties of an impurity immersed in a granular gas under stationary nonlinear Couette flow. The starting point is a kinetic model for low-density granular mixtures recently proposed by the authors [Vega Reyes F et al. 2007 Phys. Rev. E 75 061306]. Two routes have been considered. First, a hydrodynamic or normal solution is found by exploiting a formal mapping between the kinetic equations for the gas particles and for the impurity. We show that the transport properties of the impurity are characterized by the ratio between the temperatures of the impurity and gas particles and by five generalized transport coefficients: three related to the momentum flux (a nonlinear shear viscosity and two normal stress differences) and two related to the heat flux (a nonlinear thermal conductivity and a cross coefficient measuring a component of the heat flux orthogonal to the thermal gradient). Second, by means of a Monte Carlo simulation method we numerically solve the kinetic equations and show that our hydrodynamic solution is valid in the bulk of the fluid when realistic boundary conditions are used. Furthermore, the hydrodynamic solution applies to arbitrarily (inside the continuum regime) large values of the shear rate, of the inelasticity, and of the rest of parameters of the system. Preliminary simulation results of the true Boltzmann description show the reliability of the nonlinear hydrodynamic solution of the kinetic model. This shows again the validity of a hydrodynamic description for granular flows, even under extreme conditions, beyond the Navier-Stokes domain.Comment: 23 pages, 11 figures; v2: Preliminary DSMC results from the Boltzmann equation included, Fig. 11 is ne

    Landsat and local land surface temperatures in a heterogeneous terrain compared to MODIS values

    Get PDF
    Land Surface Temperature (LST) as provided by remote sensing onboard satellites is a key parameter for a number of applications in Earth System studies, such as numerical modelling or regional estimation of surface energy and water fluxes. In the case of Moderate Resolution Imaging Spectroradiometer (MODIS) onboard Terra or Aqua, pixels have resolutions near 1 km2 , LST values being an average of the real subpixel variability of LST, which can be significant for heterogeneous terrain. Here, we use Landsat 7 LST decametre-scale fields to evaluate the temporal and spatial variability at the kilometre scale and compare the resulting average values to those provided by MODIS for the same observation time, for the very heterogeneous Campus of the University of the Balearic Islands (Mallorca, Western Mediterranean), with an area of about 1 km2 , for a period between 2014 and 2016. Variations of LST between 10 and 20 K are often found at the sub-kilometre scale. In addition, MODIS values are compared to the ground truth for one point in the Campus, as obtained from a four-component net radiometer, and a bias of 3.2 K was found in addition to a Root Mean Square Error (RMSE) of 4.2 K. An indication of a more elaborated local measurement strategy in the Campus is given, using an array of radiometers distributed in the area

    Heart Rate Variability and Exceptional Longevity

    Get PDF
    Centenarians are the paradigm of human extreme longevity and healthy aging, because they have postponed, if not avoided, mayor age-related diseases. The purpose of this study was to investigate potential differences in resting heart rate variability (HRV) between young adults, octogenarians, and centenarians and assess whether HRV variables are predictors of all-cause mortality in centenarians. To this end, three groups of participants: young adults (N = 20; 20.6 ± 2.3 years), octogenarians (N = 18; 84.1 ± 2.6 years), and centenarians (N = 17; 101.9 ± 1.9 years) were monitored for 15 min at rest (seated, without moving or talking) to measure RR intervals, from which HRV was evaluated. Our results showed a clear decrease with age in the main parasympathetic HRV variables, as well as in the standard deviation (SD) of the RR series [SD of normal-to-normal interval (SDNN)] and in low frequency (LF) heart rate (HR) oscillations, although differences between octogenarians and centenarians did not reach statistical significance. In 14 centenarians followed until death, only SDNN showed significant correlation (¿ = 0.536; p = 0.048) with survival prognosis. Additionally, SDNN <19 ms was associated with early mortality (=1 year) in centenarians (Hazard Ratio = 5.72). In conclusion, HRV indices reflecting parasympathetic outflow as well as SDNN and LF all present an age-related reduction, which could be representative of a natural exhaustion of allostatic systems related to age. Moreover, low SDNN values (<19 ms) could be associated with early mortality in centenarians. HRV seems to play a role in exceptional longevity, which could be accounted for by centenarians’ exposome

    Tipos habitacionais e estratégias de reabilitação do núcleo urbano antigo do Seixal

    Get PDF
    Os núcleos urbanos antigos são portadores de um património histórico e arquitectónico a proteger e a potenciar. Para tal, é necessário compreender a sua génese, tanto no plano do edifício como no plano do conjunto urbano. Deste modo, considera-se importante o estudo do edificado como apoio a intervenções de reabilitação qualificadas, conscientes e sustentáveis. Este artigo aborda o assunto dos núcleos urbanos antigos na perspectiva da análise e inventariação das características do edificado. O processo de tipificação apresenta-se como síntese das principais formas de construção presentes, baseado na inspecção (observação e levantamento) e registo, tomando como caso de estudo o Núcleo Urbano Antigo do Seixal

    Architectonic and constructive characterisation of the old urban centre of Seixal, Portugal

    Get PDF
    This paper addresses the issue of the old urban centres from the perspective of the analysis and inventory of building features. The cataloguing process of the building typologies is presented herein as a synthesis of the main construction forms, with the old city centre of Seixal being used as a case study. Furthermore, and taking into account the relation between such two dimensions, a material and constructive characterisation of the buildings in the old urban centre of Seixal is presented. As marks of an historical and architectural heritage, old urban centres should be protected, safeguarded and potentiated. For such, it is fundamental to have a complete understanding of the genesis of both buildings and urban mesh. This fact is essential to the support of qualified, conscientious and sustainable rehabilitation interventions on the old building stock

    The Impact of Multifocal Intraocular Lens in Retinal Imaging with Optical Coherence Tomography

    Get PDF
    Multifocal intraocular lenses (MF IOLs) have concentric optical zones with different dioptric power, enabling patients to have good visual acuity at multiple focal points. However, several optical limitations have been attributed to this particular design. The purpose of this study is to access the effect of MF IOLs design on the accuracy of retinal optical coherence tomography (OCT). Cross-sectional study conducted at the Refractive Surgery Department of Central Lisbon Hospital Center. Twenty-three eyes of 15 patients with a diffractive MF IOL and 27 eyes of 15 patients with an aspheric monofocal IOL were included in this study. All patients underwent OCT macular scans using Heidelberg Spectralis®. Macular thickness and volume values and image quality (Q factor) were compared between the two groups. There were no statistically significant differences between both groups regarding macular thickness or volume measurements. Retinal OCT image quality was significantly lower in the MF IOL group (p < 0.01). MF IOLs are associated with a significant decrease in OCT image quality. However, this fact does not seem to compromise the accuracy of spectral domain OCT retinal measurements
    corecore