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Introduction to 3D reconstruction of macromolecules using single particle electron microscopy

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Acta Pharmacologica Sinica 2005年第10期26卷 1153-1164页

作者： oscar LLORCA Centro de lnvestigaciones Biológicas Consejo Superior de Investigaciones Científicas Ramiro de Maeztu 9 Campus Universidad Complutense 28040 Madrid Spain

Single-particle electron microscopy has now reached maturity, becoming a commonly used method in the examination of macromolecular structure. Using a small amount of purified protein, isolated molecules are observed under the electron microscope and the data collected can be averaged into a 3D reconstruction. Single-particle electron microscopy is an appropriate tool for the analysis of proteins that can only be obtained in modest quantities, like many of the large complexes currently of interest in biomedicine. Whilst the use of electron microscopy expands, new methods are being developed and improved to deal with further challenges, such as reaching higher resolutions and the combination of informa tion at different levels of structural detail. More importantly, present methodology is still not robust enough when studying certain "tricky" proteins like those displaying extensive conformational flexibility and a great deal of user expertise is required, posing a threat to the consistency of the final structure. This mini review describes a brief outline of the methods currently used in the 3D analysis of macromolecules using single-particle electron microscopy, intended for those first approaching this field. A summary of methods, techniques, software, and some recent work is presented. The spectacular improvements to the technique in recent years, its advantages and limitations compared to other structural methods, and its future developments are discussed.

关键词： single particle electron microscopy 3D reconstruction cryoelectron microscopy image processing DNA-PK

Lessons from International Students’ Reaction to the 2011 Great East Japan Earthquake:The Case of the School of Engineering at Tohoku University

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International Journal of Disaster Risk Science 2013年第3期4卷 137-149页

作者： oscar A.Gómez Graduate School of Global Studies Doshisha UniversityKyoto 602-0898Japan

The objective of this study is to document the reaction of international students to the 11 March 2011 emergency in order to inform and improve disaster management strategies, both public and institutional. The study is based mainly on a questionnaire survey carried out in August 2011 and follow-up interviews with students and other stakeholders. It describes the background of Tohoku University’s School of Engineering and covers six different stages in the evolution of the emergency:(1) immediate response;(2) taking shelter in Sendai;(3) life in the city during the aftermath;(4) sheltering outside Sendai;(5) coming back;plus(6) an overview of the experience. Major findings include: the process of evacuation and safety confirmation was successful, yet the subsequent phases(2 and 3) went on mostly unmanaged;students relied mostly on secondary sources of information to make decisions, mainly family and friends of the same nationality, most of whom probably were not better informed than the students themselves. Based on the findings, suggestions for future disaster planning are advanced, as well as a discussion on the challenges of information provision during crisis.

关键词： disaster mostly Great

Polygeneration Study of Low-to-Medium Enthalpy Geothermal Reservoirs in Mexico

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Journal of Thermal Science 2021年第3期30卷 1077-1087页

作者： CHÁVEZ oscar GODÍNEZ Francisco Tecnológico Nacional de México/I.T.Chihuahua.Av.Tecnológico 2909 C.P.31310ChihuahuaChihuahuaMéxico Instituto de Ingeniería Universidad Nacional Autónoma de MéxicoUNAMC.U.Ciudad de MéxicoC.P.04510México Polo Universitario de Tecnología Avanzada Universidad Nacional Autónoma de MéxicoVía de la Innovación No.410Autopista Monterrey-Aeropuertokm.10 PIITC.P.66629Apodaca Nuevo LeónMéxico

This study combines the thermodynamic analysis of a polygeneration system along with the numerical modelling of the thermal behavior of geothermal reservoirs in Mexico to exploit their *** reservoir was modeled as a porous medium assuming a five-spot well configuration and local thermal *** heat conduction-convection along with the Laplace equations were solved to compute temperature distributions,the useful life and the optimum distance between injection-extraction *** predicted temperature and pressure of the geothermal fluid at the outlet of the reservoir were exploited in the polygeneration system consisting of:(1)a Rankine cycle,(2)an absorption refrigeration cycle,and(3)a heat *** developed approach allows calculating both the optimal distance between injection-extraction wells and the global(utilization)efficiency of six arrangements(each composed by a reservoir connected to a polygeneration system)by assuming that reservoirs have a lifespan of 30 *** also show that:(a)due to the low efficiency of the Rankine cycle,very little thermal energy is converted into electrical one;(b)not only the temperature and the size are important when evaluating the power production performance of reservoirs,but also the permeability plays a fundamental role;(c)the first law efficiency of the polygeneration system ranges from 41.9%to 43.7%;(d)the utilization efficiency of the six arrangements lies in the range between 25.8%and 31%.

关键词： polygeneration system geothermal reservoir local thermal equilibrium low-to-medium enthalpy

Bile-acid-induced cell injury and protection

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World Journal of Gastroenterology 2009年第14期15卷 1677-1689页

作者： Maria J Perez oscar Briz Research Unit University Hospital of Salamanca Laboratory of Experimental Hepatology and Drug Targeting CIBERehd University of Salamanca E.D. 129 37007 Salamanca Spain

Several studies have characterized the cellular and molecular mechanisms of hepatocyte injury caused by the retention of hydrophobic bile acids （BAs） in cholestatic diseases. BAs may disrupt cell membranes through their detergent action on lipid components and can promote the generation of reactive oxygen species that, in turn, oxidatively modify lipids, proteins, and nucleic acids, and eventually cause hepatocyte necrosis and apoptosis. Several pathways are involved in triggering hepatocyte apoptosis. Toxic BAs can activate hepatocyte death receptors directly and induce oxidative damage, thereby causing mitochondrial dysfunction, and induce endoplasmic reticulum stress. When these compounds are taken up and accumulate inside biliary cells, they can also cause apoptosis. Regarding extrahepatic tissues, the accumulation of BAs in the systemic circulation may contribute to endothelial injury in the kidney and lungs. In gastrointestinal cells, BAs may behave as cancer promoters through an indirect mechanism involving oxidative stress and DNA damage, as well as acting as selection agents for apoptosis-resistant cells. The accumulation of BAs may have also deleterious effects on placental and fetal cells. However, other BAs, such as ursodeoxycholic acid, have been shown to modulate BA-induced injury in hepatocytes. The major beneficial effects of treatment with ursodeoxycholic acid are protection against cytotoxicity due to more toxic BAs; the stimulation of hepatobiliary secretion; antioxidant activity, due in part to an enhancement in glutathione levels; and the inhibition of liver cell apoptosis. Other natural BAs or their derivatives, such as cholyI-N- methylglycine or pharmacological properties. cholylsarcosine, interest owing have also aroused to their protective

关键词： Apoptosis Cholestasis liver Necrosis Oxidative stress Ursodeoxycholic acid

TWO NOVEL GRADIENT METHODS WITH OPTIMAL STEP SIZES

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Journal of Computational Mathematics 2021年第3期39卷 375-391页

作者： Harry Oviedo oscar Dalmau Rafael Herrera Centro de Investigacion en Matematicas CIMAT A.C.GuanajuatoGto.Mexico

In this work we introduce two new Barzilai and Borwein-like steps sizes for the classical gradient method for strictly convex quadratic optimization *** proposed step sizes employ second-order information in order to obtain faster gradient-type *** step sizes are derived from two unconstrained optimization models that involve approximate information of the Hessian of the objective function.A convergence analysis of the proposed algorithm is *** numerical experiments are performed in order to compare the efficiency and effectiveness of the proposed methods with similar methods in the ***,it is observed that our proposals accelerate the gradient method at nearly no extra computational cost,which makes our proposal a good alternative to solve large-scale problems.

关键词： Gradient methods Convex quadratic optimization Hessian spectral properties Steplength selection

Oviposition behavior of the mirid Macrolophus pygmaeus under risk of intraguild predation and cannibalism

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Insect Science 2021年第1期28卷 224-230页

作者： Frangois Dumont Eric Lucas oscar Alomar Departement des Sciences Biologiques Universite du Quebec a MontrealCentre VilleMontrealQCCanada Sustainable Plant Protection Programme Institute of Agri food Research and Technology(IRTA)CabrilsCataloniaSpain

Zoophytophagous mirid species,that feed and develop either on prey or plant resources,are often found simultaneously on the same ***,these species can engage in both intraguild predation and cannibalism,which can pose a threat to mirid *** females may respond to such risks of predation on their eggs by reducing the number of eggs laid or selecting safer oviposition *** tested the oviposition behavior of Macrolophus pygmaeus(Rambur)(Hemiptera:Miridae)females under the risk of cannibalism by *** males and intraguild predation by Nesidiocoris tenuis(Reuter)males(Hemiptera:Miridae)under laboratory *** predators and cannibals were introduced during or after the oviposition *** number of eggs laid(using counts of newly hatched nymphs)and their proportion on each part of a tomato plant were both *** results reveal that only cannibalism by *** males after the period of oviposition significantly decreased the number of hatched *** thus represents a greater risk to mirid eggs than intraguild *** *** female responded to the presence of potential intraguild predators(or competitors)by decreasing the nu mber of eggs laid in the upper *** results suggest that *** females avoid competition by ***,by laying fewer eggs on upper *** could regulate zoophytophagous predator populations under prey scarcity conditions and minimize the risk of crop damage associated with those biological control agents.

关键词： antipredator behavior cannibalism intraguild predation Macrolophus pygmaeus',Nesidiocoris tenuis zoophytophagy

A Survey on Type-3 Fuzzy Logic Systems and Their Control Applications

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IEEE/CAA Journal of Automatica Sinica 2024年第8期11卷 1744-1756页

作者： oscar Castillo Fevrier Valdez Patricia Melin Weiping Ding Tijuana Institute of Technology/Tecnologico Nacional de Mexico Division of Graduate StudiesCalzada Tecnologico S/NTijuana 22414Mexico School of Information Science and Technology Nantong UniversityJiangsu 226019China

In this paper,we offer a review of type-3 fuzzy logic systems and their applications in *** main objective of this work is to observe and analyze in detail the applications in the control area using type-3 fuzzy logic *** this case,we review their most important applications in control and other related topics with type-3 fuzzy *** algorithms have been receiving increasing attention in control and for this reason a review in this area is *** paper reviews the main applications that make use of Intelligent Computing ***,type-3 fuzzy logic *** aim of this research is to be able to appreciate,in detail,the applications in control systems and to point out the scientific trends in the use of Intelligent Computing *** is done with the construction and visualization of bibliometric networks,developed with VosViewer Software,which it is a free Java-based program,mainly intended to be used for analyzing and visualizing bibliometric *** this tool,we can create maps of publications,authors,or journals based on a co-citation network or construct maps of keywords,countries based on a co-occurrence networks,research groups,etc.

关键词： Applications control systems optimization review type-3 fuzzy logic.

Processing of ingredients and diets and effects on nutritional value for pigs

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Journal of Animal Science and Biotechnology 2017年第4期8卷 751-763页

作者： oscar Javier Rojas Hans Henrik Stein Devenish Nutrition Fairmont MN 56031 USA Department of Animal Sciences University of Illinois Urbana IL 61801 USA.

A conventional diet based on corn and soybean meal fed to pigs is usually provided in a mash form and in most cases, processing other than grinding and mixing is not used. However, due to the high cost of energy in pig diets,use of high fiber ingredients such as soybean hulls, distillers dried grains with solubles, and wheat middlings has increased. High fiber concentrations in the diet usually results in reduced energy and nutrient digestibility due to the low capacity of pigs to digest fiber, which negatively impacts growth performance and carcass composition of the pigs. Feed processing technologies such as changes in grinding procedures, expansion, extrusion, pelleting, use of enzymes or chemical treatments may, however, be used to solubilize some of the cel ulose and hemicel ulose fractions that form the cel wal of plants in the ingredients, and therefore, increase nutrient availability. This may have a positive effect on energy digestibility, and therefore, also on pig growth performance and carcass composition, but effects of different feed technologies on the nutritional value of feed ingredients and diets fed to pigs are not fully understood. It has however, been demonstrated that reduced particle size of cereal grains usually results in increased digestibility of energy, primarily due to increased digestibility of starch. Extrusion or expansion of ingredients or diets may also increase energy digestibility and it appears that the increase is greater in high fiber diets than in diets with lower concentrations of fiber. Chemical treatments have not consistently improved energy or nutrient digestibility, but a number of different enzymes may be used to increase the digestibility of phosphorus, calcium, or energy. Thus, there are several opportunities for using feed technology to improve the nutritional value of diets fed to pigs.

关键词： Chemical treatments Enzymes Particle size Pig Processing Starch

Weighted Weak-type Estimates for Multilinear Commutators of Fractional Integrals on Spaces of Homogeneous Type

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Acta Mathematica Sinica,English Series 2007年第10期23卷 1813-1826页

作者： Osvaldo GOROSITO Gladis PRADOliNI oscar SAliNAS Department of Mathematics Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina

We obtain weighted distributional inequalities for multilinear commutators of the fractional integral on spaces of homogeneous type, The techniques developed in this work involve the behavior of some fractional maximal functions. In relation to these operators, as a main tool, we prove a weighted weak type boundedness result, which is interesting in itself.

关键词： commutators fractional integral operator multilinear operators