750 research outputs found
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
Consumer preferences and willingness to pay for organic apples
Cerda, AA (reprint author), Univ Talca, Fac Ciencias Empresariales, 2 Norte 685, Talca, Chile.This study provides marketing data regarding consumer preferences and willingness to pay for organic agricultural products in Chile. The main objectives of this study were to assess consumer willingness to pay for organic apples and to determine the main attributes that consumers look for when purchasing apples. The methodology applied to reach the first objective was the contingent valuation method using a logistic probability function and a single-bound dichotomous choice format. Additionally, this study estimates the marginal willingness to pay (WTP) of consumers for organic apples by using conjoint analysis with ranking procedures. This study was performed in the city of Talca, Chile, where a total of 400 individuals from a probability sampling were interviewed. The results of our study show that the estimation of part-worth utilities of each attribute confirms that the Fuji variety, organic method of production, sweet apples and lowest price are the most preferred levels of each attribute. However, an analysis of the relative utility index shows that price and variety are much more important to consumer choice and behavior than the method of production and flavor. Finally, our study shows a positive willingness to pay an additional 130 Chilean pesos per kilogram for organic apples and a greater preference for apples produced organically than by conventional methods. These results provide important information about market opportunities as well as policy implementation regarding the production of organic agricultural products
Intestinal microbiota influences non-intestinal related autoimmune diseases
Indexación: Scopus.The human body is colonized by millions of microorganisms named microbiota that interact with our tissues in a cooperative and non-pathogenic manner. These microorganisms are present in the skin, gut, nasal, oral cavities, and genital tract. In fact, it has been described that the microbiota contributes to balancing the immune system to maintain host homeostasis. The gut is a vital organ where microbiota can influence and determine the function of cells of the immune system and contributes to preserve the wellbeing of the individual. Several articles have emphasized the connection between intestinal autoimmune diseases, such as Crohn's disease with dysbiosis or an imbalance in the microbiota composition in the gut. However, little is known about the role of the microbiota in autoimmune pathologies affecting other tissues than the intestine. This article focuses on what is known about the role that gut microbiota can play in the pathogenesis of non-intestinal autoimmune diseases, such as Grave's diseases, multiple sclerosis, type-1 diabetes, systemic lupus erythematosus, psoriasis, schizophrenia, and autism spectrum disorders. Furthermore, we discuss as to how metabolites derived from bacteria could be used as potential therapies for non-intestinal autoimmune diseases. © 2018 Opazo, Ortega-Rocha, Coronado-Arrázola, Bonifaz, Boudin, Neunlist, Bueno, Kalergis and Riedel.https://www.frontiersin.org/articles/10.3389/fmicb.2018.00432/ful
Applying MILP-based algorithms to automated job-shop scheduling problems in aircraft-part manufacturing
This work presents efficient algorithms based on Mixed-Integer Linear Programming (MILP) for complex job-shop scheduling problems raised in Automated Manufacturing Systems. The aim of this work is to find alternative solution approaches of production and transportation operations in a multi-product multistage production process that can be used to solve industrial-scale problems with reasonable computational effort. The MILP model developed must take into account; dissimilar recipes, single unit per production stage, re-entrant flows, sequence- dependent free transferring times and load transfer movements in a single automated material-handling device. In addition, logical-based strategies are proposed to iteratively find and improve the solutions generated over time. These approaches were tested in different real-world problems appeared in the surfacetreatment process of metal components in aircraft manufacturing industry.Sociedad Argentina de Informática e Investigación Operativ
Applying MILP-based algorithms to automated job-shop scheduling problems in aircraft-part manufacturing
This work presents efficient algorithms based on Mixed-Integer Linear Programming (MILP) for complex job-shop scheduling problems raised in Automated Manufacturing Systems. The aim of this work is to find alternative solution approaches of production and transportation operations in a multi-product multistage production process that can be used to solve industrial-scale problems with reasonable computational effort. The MILP model developed must take into account; dissimilar recipes, single unit per production stage, re-entrant flows, sequence- dependent free transferring times and load transfer movements in a single automated material-handling device. In addition, logical-based strategies are proposed to iteratively find and improve the solutions generated over time. These approaches were tested in different real-world problems appeared in the surfacetreatment process of metal components in aircraft manufacturing industry.Sociedad Argentina de Informática e Investigación Operativ
Applying MILP-based algorithms to automated job-shop scheduling problems in aircraft-part manufacturing
This work presents efficient algorithms based on Mixed-Integer Linear Programming (MILP) for complex job-shop scheduling problems raised in Automated Manufacturing Systems. The aim of this work is to find alternative solution approaches of production and transportation operations in a multi-product multistage production process that can be used to solve industrial-scale problems with reasonable computational effort. The MILP model developed must take into account; dissimilar recipes, single unit per production stage, re-entrant flows, sequence- dependent free transferring times and load transfer movements in a single automated material-handling device. In addition, logical-based strategies are proposed to iteratively find and improve the solutions generated over time. These approaches were tested in different real-world problems appeared in the surfacetreatment process of metal components in aircraft manufacturing industry.Sociedad Argentina de Informática e Investigación Operativ
Degradación de rojo congo en un fotorreactor tubular de tecnología excimer. Estudio cinético
Como ampliación al estudio realizado sobre la fotodegradación de rojo congo con lámparas discontinuas de tecnologíaexcimer de XeBr, KrCl y Cl2, en este trabajo se ha estudiado la fotodegradación de dicho colorante mediante un fotorreactor continuo de KrCl, con recirculación, con H2O2 y con reactivo Fenton. Del estudio de la influencia de las condiciones de operación, se han seleccionado los valores de caudal y de concentración inicial de rojo congo óptimos para su degradación. Adicionalmente, se ha comprobado que la degradación de rojo congo mejora al aumentar la cantidad de H2O2 adicionada al medio hasta una relación molar H2O2: rojo congo de 75:1 a partir de la cual ya no aumenta más. Además, la fotodegradación de rojo congo también se ve favorecida al aumentar la concentración de Fe2+ al utilizar el reactivo Fenton.El modelo modificado de pseudo primer orden propuestopreviamente se ha aplicado a este tipo de reactor. Delajuste del modelo, se ha obtenido la tendencia de la constantede velocidad (k), para las diferentes series experimentales.Además, los valores calculados con el modelopara la conversión de rojo congo se han comparado conlos experimentales, obteniéndose un buen ajuste lineal.Finalmente, se ha realizado un análisis ANOVA confirmándosela validez del modelo
Obtaining foot bone structure applying global and adaptive thresholding
La descripción del comportamiento mecánico de tejidos duros mediante el empleo de modelos discretos pasa por diferentes etapas de análisis, que van desde el procesamiento digital de la imagen hasta la especificación de las propiedades físicas del tejido al modelo discreto. Para lograr un buen resultado es esencial la descomposición de esos modelos en sus partes constitutivas.
En este trabajo se discute un método para la descripción geométrica de los huesos del pie a partir de una secuencia de imágenes (cortes) de tomografía computarizada (TC).
La investigación propone la combinación de la umbralización global y de la adaptativa para la determinación del dominio geométrico de los huesos en cada corte, así como el análisis de las relaciones espaciales entre contornos en planos consecutivos a fin de obtener las isosuperficies de los huesos.
Se propone un algoritmo semiautomático basado en 4 etapas: la lectura de los cortes de imágenes de TC; la determinación de los contornos que definen el tejido óseo presentes en cada corte; la formación de los volúmenes a través del agrupamiento de los contornos cuya relación espacial cumple un criterio determinado; y la eliminación de las isosuperficies no válidas.
Como resultado se obtiene la definición de la mayoría de los huesos del pie cuyo rango de valores en la escala de Hounsfield es [–1.000; 1.383].The description of the mechanical behavior of hard tissues by means of discrete models goes through various stages of analysis, which range from digital image processing to the specification of tissues physical properties to the discrete model. To achieve good results it is essential to decompose these models into their constituent parts.
In this paper we discuss a method for geometrical description of foot bones from a sequence of computed tomography (CT) images.
This research proposes a combination between global and adaptive thresholdings to determine the geometric domain of bones in each slice and the analysis of the spatial relationships between contours in consecutive planes in order to obtain bones’ isosurfaces.
The algorithm proposed is based on 4 stages: the reading of computed tomography (CT) images; the determination of the contours that define the bone tissue present on each slice; the grouping of contours whose relationship meet a given criteria; the elimination of non-valid volumes.
As a result, it is possible to obtain the geometrical domain of a great number of foot bones whose range in the Hounsfield is [–1000; 1383].Peer Reviewe
Algorithm for defining skeletal structures in biomedical models
La descripción del comportamiento mecánico de tejidos duros mediante el empleo de modelos discretos pasa por diferentes etapas de análisis, desde el procesamiento digital de la imagen hasta la especificación de las propiedades físicas del tejido. Para ello, es necesario tener en cuenta un elemento clave: la descomposición del modelo en sus partes constitutivas. Se realizó un estudio bibliográfico de diversas propuestas para realizar la descomposición y se llegó a la conclusión de la inexistencia de una estrategia única. Existe un cúmulo de propuestas genéricas, pero estas no ofrecen una solución válida a los casos analizados, correspondientes a las articulaciones de la rodilla, la pelvis y el hombro. Por tanto, se propone un algoritmo para realizar la descomposición mediante el análisis de las relaciones espaciales entre los contornos presentes en planos consecutivos, que se basa en 4 etapas: la lectura de los cortes de imágenes de tomografía computarizada; la determinación de los contornos que definen el tejido óseo presente en cada corte; el agrupamiento de los contornos cuya relación espacial cumple un criterio determinado, y la eliminación de los volúmenes no válidos.
Los resultados del algoritmo se compararon con otros obtenidos mediante el empleo de la librería Visualization ToolKit (VTK) y pyFormex, cuyos métodos se utilizan en la visualización y análisis de imágenes médicas y en la modelación de estructuras tridimensionales. Como resultado del algoritmo propuesto tenemos —bajo las mismas condiciones y en un corto tiempo de procesamiento— una descomposición de los modelos anatómicos superior a la realizada por VTK y pyFormex, con aproximadamente el 90% de confianza.Description of mechanical behavior of hard tissues by means of discrete models goes through various stages of analysis, which range from digital image processing to the specification of physical properties of tissue to the discrete model. This requires taking into account a key element: the decomposition of the model into its constituent parts. We conducted a bibliographic study of existing proposals for such decomposition, leading to the conclusion of the absence of a single strategy. There are several generic proposals, but these proved not to give a valid solution applicable to the cases examined corresponding to the articulations of the knee, hip and shoulder. In this paper we propose an algorithm to perform this decomposition by analyzing the spatial relationships between the contours present in consecutive planes. It is based on four stages: reading computer tomography (CT) slices; determining the contours that define bone tissue present on each slice; grouping of contours whose relationship meets a given criterion; and eliminating non-valid volumes.
Results were compared with those obtained by means of Visualization ToolKit (VTK) and pyFormex, widely used in the visualization and analysis of medical imaging and modeling three-dimensional structures. As a main result, proposed algorithm under the same conditions and short processing time performs a better decomposition of anatomical models than the one made by VTK and pyFormex, with about a 90% of confidence.Peer Reviewe
An electrochemical Study of Phenol Oxidation in Acidic Medium
[EN] This work addresses the electrooxidation of phenol on platinum electrodes applying cyclic voltametry.
The effect of different parameters on the electrooxidation of phenol, such as the scan rate, the
inversion potential, the phenol concentration, the sulphuric acid concentration, and the stirring of the
solution, were investigated using a conventional three-electrode cell. The results show the presence of
an oxidation peak in the region around 1V vs Ag/AgCl to all conditions evaluated. In cyclic
voltametric experiments a gradual decrease of the oxidation peak with the number of cycles was
observed, and after about four cycles there was no more evidence of a peak. This behavior was
repeated for all phenol and sulphuric acid concentrations studied. This suggests the deactivation or
blockage of the electrode surface by the adsorption of substances and/or phenoxy radical
polymerization.We wish to express our gratitude for the support of this work by the CAPES Brazil (ref. no. 080/04) and the Ministerio de Ciencia y Tecnología Spain (ref. no. PHB2003-0093-PC)Xavier, J.; Ortega Navarro, EM.; Ferreira, J.; Bernardes, A.; Pérez-Herranz, V. (2011). An electrochemical Study of Phenol Oxidation in Acidic Medium. International Journal of Electrochemical Science. 6(3):622-636. http://hdl.handle.net/10251/150343S6226366
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