A Star Harbouring a Wormhole at its Core

We consider a configuration consisting of a wormhole filled by a perfect fluid. Such a model can be applied to describe stars as well as neutron stars with a nontrivial topology. The presence of a tunnel allows for motion of the fluid, including oscillations near the core of the system. Choosing the polytropic equation of state for the perfect fluid, we obtain static regular solutions. Based on these solutions, we consider small radial oscillations of the configuration and show that the solutions are stable with respect to linear perturbations in the external region.Comment: abstract was change

Approach to a classification of construction typologies of pig facilities: case study Antioquia – Colombia

Received: January 31th, 2021 ; Accepted: March 27th, 2021 ; Published: April 30th, 2021 ; Correspondence: [email protected] facilities foro confined production in tropical countries such as Colombia does not specify, in the present moment a typological classification that allows researchers to carry out evaluations related to animal comfort and environmental impacts according to the type of accommodation. To achieve the objective of this research were developed a survey to a panel of experts, a decision sensitivity analysis and the hierarchical analytical method AHP. Parameters that allowed to describe the concept of a technified pig farm were obteined, where the most relevant were: biosecurity measures, measurement of zootechnical parameters, training for workers and legal fulfilment. Additionally, ranges were defined to establish the production size in small, medium and large according to the number of animals. The results obtained per group were: 1) breeding small (50–200), medium (201–1,000) and large (1,001–5,000); 2) growth small (60–200), medium (201–800) and large (801–5000); and 3) finishing stage small (50–500), medium (501–1,000) and large (2,001–5,000). A total of 948 typological combinations were initially determined. Finally, the construction characteristics with the greatest technical and operational feasibility were prioritized for each group achieving 36 typologies that can represent the typological pig facilities not only in the state of Antioquia but also in many others states in Colombia

Human metapneumovirus: Mechanisms and molecular targets used by the virus to avoid the immune system

Indexación: Scopus.This work was supported by Comisión Nacional de Investigación Científica y Tecnolígica (CONICYT) N◦21151028 and FONDECYT (N◦1070352 and N◦1170964) and the Millennium Institute on Immunology and Immunotherapy (P09/016-F).Human metapneumovirus (hMPV) is a respiratory virus, first reported the year 2001. Since then, it has been described as one of the main etiological agents that causes acute lower respiratory tract infections (ALRTIs), which is characterized by symptoms such as bronchiolitis, wheezing and coughing. Susceptible population to hMPV-infection includes newborn, children, elderly and immunocompromised individuals. This viral agent is a negative-sense, single-stranded RNA enveloped virus, that belongs to the Pneumoviridae family and Metapneumovirus genus. Early reports-previous to 2001-state several cases of respiratory illness without clear identification of the responsible pathogen, which could be related to hMPV. Despite the similarities of hMPV with several other viruses, such as the human respiratory syncytial virus or influenza virus, mechanisms used by hMPV to avoid the host immune system are still unclear. In fact, evidence indicates that hMPV induces a poor innate immune response, thereby affecting the adaptive immunity. Among these mechanisms, is the promotion of an anergic state in T cells, instead of an effective polarization or activation, which could be induced by low levels of cytokine secretion. Further, the evidences support the notion that hMPV interferes with several pattern recognition receptors (PRRs) and cell signaling pathways triggered by interferon-associated genes. However, these mechanisms reported in hMPV are not like the ones reported for hRSV, as the latter has two non-structural proteins that are able to inhibit these pathways. Several reports suggest that viral glycoproteins, such as G and SH, could play immune-modulator roles during infection. In this work, we discuss the state of the art regarding the mechanisms that underlie the poor immunity elicited by hMPV. Importantly, these mechanisms will be compared with those elicited by other common respiratory viruses. © 2018 Frontiers Media S.A. All rights reserved.https://www.frontiersin.org/articles/10.3389/fimmu.2018.02466/ful

Changes in Rift Valley fever neutralizing antibody prevalence among small domestic ruminants following the 1987 outbreak in the Senegal River bassin

Deux séries d'enquêtes sérologiques ont été menées dans la région du bassin versant du fleuve Sénégal où a eu lieu une manifestation épidémoépizootique du virus de la fièvre de la vallée du Rift (FVR) en 1987. Deux échantillons de sérums ont été prélevés respectivement en 1988 et en 1989 chez 303 et 331 petits ruminants (chèvres et moutons) pris au hasard et ont été testés pour la mise en évidence d'anticorps neutralisants. Sur les 634 animaux testés au total et respectivement en 1988 et en 1989, la séroprévalence est de 24,4 et 19,3%. La prévalence en anticorps neutralisant contre l'antigène RVF est significativement moins élevée chez les jeunes animaux (7,9%) que chez les adultes (25,3%). Dans la période post-épizootique de 1988 à 1989, une surveillance suivie permet de conclure en faveur d'une absence de circulation active du virus de la FVR chez les ruminants domestiques du Nord-Sénégal. Le renouvellement rapide de la population non immune de petits ruminants représente un risque potentiel épizootique et secondairement épidémique dans cette zone sahélienne d'enzootie connu

Monitoring of evoked potentials during spinal cord ischaemia: Experimental evaluation in a rabbit model

Objectives:somatosensory evoked potentials (SEPs), spinal evoked potentials (Spinal-EPs), and motor-evoked potentials (MEPs) were monitored in a rabbit model of spinal cord ischaemia to evaluate their accuracy and relationship to clinical status.Methods:a modified rabbit spinal cord ischaemia model of infrarenal aortic occlusion for 21 min was employed (30 rabbits). After baseline SEPs, Spinal-EPs, and MEPs were obtained, evoked potentials were recorded continuously during and after clamping of the aorta (30 min). Neurological outcome at 24 h was correlated with evoked potentials, and histopathological findings.Results:fifteen animals became paraplegic. MEPs were always abolished after clamping of the aorta while Spinal-EPs and SEPs remained. The sensory evoked potentials (SEPs and Spinal-EPs) were the least sensitive to spinal cord ischaemia, and their presence had no correlation with the final clinical status (50% of false negatives). This was consistent with histopathological examination that showed damage almost entirely confined to the anterior horn, while the dorsal columns were generally well preserved. High spine MEPs evoked by twitch stimulation was the best predictor of clinical outcome (0% of false negatives, 0% of false positives).Conclusions:SEPs and Spinal-EPs cannot be used as safe monitors of ischaemia of the spinal cord. High spine MEPs evoked by twitch stimulation was the most useful for real-time evaluation of spinal cord ischaemia, and the best predictor of neurologic outcome during reperfusion

Effects of weather and other factors on milk production in the Churra dairy sheep breed

The objective of this study was to investigate the influence of meteorological and other factors on the quality and quantity of milk of the Spanish Churra sheep breed, based on an analysis of 359, 808 milk controls from 9, 904 ewes on 15 farms in 8 years. Daily milk yield (DMY), fat, protein, and lactose (%), and somatic cell count (SCC) data were obtained from monthly alternating milk controls. Mean, maximum, and minimum temperatures (T) (°C), mean relative humidity (RH) (%), wind speed (WS, m/s), mean solar radiation (SR, MJ/m2), and total rainfall (RF, mm) on the day before each milk control day were documented. Year, farm, number of lambing and stage of lactation, and all of the meteorological factors had a significant (P < 0.0001) effect on DMY and milk quality. DMY and SCC differed among seasons (P < 0.001), and maximum DMY and minimum SCC occurred in spring, and minimum DMY and maximum SCC occurred in autumn. Fat, protein, and lactose content differed significantly (P < 0.001) among seasons, and fat and protein contents were highest in autumn. DMY was highest in the second lambing of the ewe and steadily declined in subsequent lambings. SCC increased significantly from the first to the 10th lambing of the ewe. DMY, SCC, and fat content differed significantly (P < 0.001) among years. In conclusion, meteorological conditions had a significant effect on milk quality and production in Churra sheep conditions in a season-dependent manner such that factors such as temperature had the opposite effect on milk production in hot and cold seasons

Spectral Reconstruction and Noise Model Estimation Based on a Masking Model for Noise Robust Speech Recognition

An effective way to increase noise robustness in automatic speech recognition (ASR) systems is feature enhancement based on an analytical distortion model that describes the effects of noise on the speech features. One of such distortion models that has been reported to achieve a good trade-off between accuracy and simplicity is the masking model. Under this model, speech distortion caused by environmental noise is seen as a spectral mask and, as a result, noisy speech features can be either reliable (speech is not masked by noise) or unreliable (speech is masked). In this paper, we present a detailed overview of this model and its applications to noise robust ASR. Firstly, using the masking model, we derive a spectral reconstruction technique aimed at enhancing the noisy speech features. Two problems must be solved in order to perform spectral reconstruction using the masking model: (1) mask estimation, i.e. determining the reliability of the noisy features, and (2) feature imputation, i.e. estimating speech for the unreliable features. Unlike missing data imputation techniques where the two problems are considered as independent, our technique jointly addresses them by exploiting a priori knowledge of the speech and noise sources in the form of a statistical model. Secondly, we propose an algorithm for estimating the noise model required by the feature enhancement technique. The proposed algorithm fits a Gaussian mixture model to the noise by iteratively maximising the likelihood of the noisy speech signal so that noise can be estimated even during speech-dominating frames. A comprehensive set of experiments carried out on the Aurora-2 and Aurora-4 databases shows that the proposed method achieves significant improvements over the baseline system and other similar missing data imputation techniques

Sistemas de carga y transporte del tomate para industria

En el cultivo de las hortalizas para industria, la fase de post-cosecha, entendiendo como tal las operaciones que hay que realizar desde que el producto es recolectado hasta que entra en las líneas de fabricación, reviste una importancia capital puesto que influye directamente sobre la calidad de la materia prima con la que se elaborarán las conservas. En el caso del tomate para industria la importancia de la post-cosecha se deriva de la fragilidad del fruto que ha de ser manipulado y del gran volumen de frutos que ha de ser transportado (en algunas industrias hasta 2.000 t/día), lo que obliga a organizar una infraestructura de transporte complicada y cara