检索结果-南通市图书馆

A MIXED VIRTUAL ELEMENT METHOD FOR THE BOUSSINESQ PROBLEM ON POLYGONAL MESHES

Journal of Computational Mathematics 2021年第3期39卷 392-427页

作者： Gabriel N.Gatica Mauricio Munar Filander A.Sequeira CI^2 MA and Departamento de Ingenieria Matemitica Universidad de ConcepcionCasilla 160-CConcepcionChile Escuela de Matemaitica Universidad NacionalCampus Omar DengoHerediaCosta Rica

In this work we introduce and analyze a mixed virtual element method(mixed-VEM)for the two-dimensional stationary Boussinesq *** continuous formulation is based on the introduction of a pseudostress tensor depending nonlinearly on the velocity,which allows to obtain an equivalent model in which the main unknowns are given by the aforementioned pseudostress tensor,the velocity and the temperature,whereas the pressure is computed via a postprocessing *** addition,an augmented approach together with a fixed point strategy is used to analyze the well-posedness of the resulting continuous *** the discrete problem,we follow the approach employed in a previous work dealing with the Navier-Stokes equations,and couple it with a VEM for the convection-diffusion equation modelling the *** precisely,we use a mixed-VEM for the scheme associated with the fluid equations in such a way that the pseudostress and the velocity are approximated on virtual element subspaces of H(div)and H^(1),respectively,whereas a VEM is proposed to approximate the temperature on a virtual element subspace of H^(1).In this way,we make use of the L^(2)-orthogonal projectors onto suitable polynomial spaces,which allows the explicit integration of the terms that appear in the bilinear and trilinear forms involved in the scheme for the fluid *** the other hand,in order to manipulate the bilinear form associated to the heat equations,we define a suitable projector onto a space of polynomials to deal with the fact that the diffusion tensor,which represents the thermal conductivity,is ***,the corresponding solvability analysis is performed using again appropriate fixed-point ***,Strang-type estimates are applied to derive the a priori error estimates for the components of the virtual element solution as well as for the fully computable projections of them and the postprocessed *** corresponding rates of convergence are als

关键词： Boussinesq problem Pseudostress-based formulation Augmented formulation Mixed virtual element method.High-order approximations

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Microhabitat heterogeneity associated with Vanilla *** its influences on the microbial community of leaf litter and soil

引用

Soil Ecology Letters 2020年第3期2卷 195-208页

作者： Gabriela Montes de Oca-Vasquez Frank Solano-Campos Bernal Azofeifa-Bolanos Amelia Paniagua-Vasquez Jose Vega-Baudrit Antonio Ruiz-Navarro Ruben Lopez-Mondejar Felipe Bastida National Nanotechnology Laboratory National Center for High Technology10109 PavasSan JoseCosta Rica School of Biological Sciences Universidad NacionalCampus Omar Dengo86-3000 HerediaCosta Rica Asociacion Nacional de Vainilleros Unidos San JoseCosta Rica Instituto de Investigacion y Servicios Forestales Universidad Nacional86-3000 HerediaCosta Rica Laboratory of Polymer Science and Technology School of ChemistryUniversidad NacionalCampus Omar Dengo86-3000 HerediaCosta Rica CEBAS-CSIC Department of Soil and Water ConservationCampus Universitario de Espinardo30100MurciaSpain Laboratory of Environmental Microbiology Institute of Microbiology of the CASVidenska 1083Praha 414220Czech Republic

The impact of forest microhabitats on physiochemical properties of the soil and that of microbial communities on tropical soils remain poorly *** elucidate the effect of tropical forest stand on leaf litter and soil microbial communities,we studied enzyme activities,microbial biomass,and diversity in three distinct microhabitats in terms of plant richness,diameter at breast height(DBH),and physiochemical properties of soil and litter,each associated with a different Vanilla *** the soil,positive correlations were found between electrical conductivity(EC)and total organic carbon(TOC)with phosphatase activity,and between nitrogen(N)and water-soluble carbon(WSC)content with urease activity(UA).In the litter,the water content was positively correlated with bacterial and fungal biomass,and N and WSC contents were positively correlated with fungal *** correlations were found between plant richness and UA in the soil,plant richness and fungal biomass in the soil and litter,and DBH and fungal biomass in the *** sequencing revealed differences between microhabitats in the relative abundance of some fungal and bacterial taxa and in the bacterial community composition of both litter and *** richness and diversity were different between microhabitats,and,in litter samples,they were negatively correlated with DBH and plant richness,*** contrast,none of the soil and litter physiochemical properties were significantly correlated with microbial *** results show that significant shifts in enzyme activity,microbial biomass,and diversity in the microhabitats were driven by key abiotic and biotic factors depending on the soil or litter sample type.

关键词： Tropical rainforest Enzyme activity Microbial community composition Microbial biomass Plant richness

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Sperm kinematic, head morphometric and kinetic- morphometric subpopulations in the blue fox （Alopex lagopus）

引用

Asian Journal of Andrology 2017年第2期19卷 154-159页

作者： Caries Soler Jesus Contell Lorena Bori Maria Sancho Almudena Garcia-Molina Anthony Valverde Jan Segarvall Department of Functional Biology and Physical Anthropology University of Valencia 46100 Burjassot Spain R+D Department Proiser R+D Scientific Park University of Valencia 46980 Paterna Spain Technological Institute of costa Rica San Carlos Campus School of Agronomy 223-21001 Alajuela Costa Rica Finnish Fur Breeders Association ProFur 65101 Vaasa Finland

This work provides information on the blue fox ejaculated sperm quality needed for seminal dose calculations. Twenty semen samples, obtained by masturbation, were analyzed for kinematic and morphometric parameters by using CASA-Mot and CASA-Morph system and principal component （PC） analysis. For motility, eight kinematic parameters were evaluated, which were reduced to PC1, related to linear variables, and PC2, related to oscillatory movement. The whole population was divided into three independent subpopulations： SP1, fast cells with linear movement; SP2, slow cells and nonoscillatory motility; and SP3, medium speed cells and oscillatory movement. In almost all cases, the subpopulation distribution by animal was significantly different. Head morphology analysis generated four size and four shape parameters, which were reduced to PC 1, related to size, and PC2, related to shape of the cells. Three morphometric subpopulations existed. SPI： large oval cells; SP2： medium size elongated cells; and SP3. small and short cells. The subpopulation distribution differed between animals. Combining the kinematic and morphometric datasets produced PC1, related to morphometric parameters, and PC2, related to kinematics, which generated four sperm subpopulations - SPI.. high oscillatory motility, large and short heads; SP2; medium velocity with small and short heads; SP3. slow motion small and elongated cells; and SP4. high linear speed and large elongated cells. Subpopulation distribution was different in all animals. The establishment of sperm subpopulations from kinematic, morphometric, and combined variables not only improves the well-defined fox semen characteristics and offers a good conceptual basis for fertility and sperm preservation techniques in this species, but also opens the door to use this approach in other species, included humans.

关键词： integration of motility and morphology principal component analysis sperm morphometry subpopulation

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Updating semen analysis:a subpopulation approach

引用

Asian Journal of Andrology 2020年第1期22卷 118-119页

作者： Almudena Garcia-Molina Anthony Valverde Daznia Bompart Carina Caldeira Alberto Vendrell Carles Soler Proiser R+D S.L. Scientific ParkUniversitat de ValenciaPaterna 46980ValenciaSpain Department of Functional Biology and Physical Anthropology University of ValenciaBurjassot 46100ValenciaSpain Technological Institute of costa Rica San Carlos CampusSchool of AgronomyAlajuela 223-21001Costa Rica

Dear Editor,Reproductive problems affect 8%-12%of human populations worldwide;40%-50%of all infertility cases are due to the male,and up to 2%of men have suboptimal sperm quality.

关键词： dating cases infertility

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Morphometric comparison by the ISAS CASA-DNAf system of two techniques for the evaluation of DNA fragmentation in human spermatozoa

引用

Asian Journal of Andrology 2016年第6期18卷 835-839页

作者： Sara Sadeghi Almudena Garcia-Molina Ferran Celma Anthony Valverde Sogol Fereidounfar Caries Soler Department of Functional Biology and Physical Anthropology University of Valencia 46100 Burjassot Valencia Spain R+D Department Proiser R+D Scientific Park Universitat de Valencia 46980 Paterna Valencia Spain Technological Institute of costa Rica San Carlos Campus School of Agronomy 223-21001 Alajuela Costa Rica Department of Botany Kharazmi University Tehran Iran

DNA fragmentation has been shown to be one of the causes of male infertility, particularly related to repeated abortions, and different methods have been developed to analyze it. In the present study, two commercial kits based on the SCD technique （Halosperm~ and SDFA） were evaluated by the use of the DNA fragmentation module of the ISAS vl CASA system. Seven semen samples from volunteers were analyzed. To compare the results between techniques, the Kruskal-Wallis test was used. Data were used for calculation of Principal Components （two PCs were obtained）, and subsequent subpopulations were identified using the Halo, Halo/Core Ratio, and PC data. Results from both kits were significantly different （P 〈 0.001）. In each case, four subpopulations were obtained, independently of the classification method used. The distribution of subpopulations differed depending on the kit used. From the PC data, a discriminant analysis matrix was obtained and a good a posterioriclassification was obtained （97.1% for Halosperm and 96.6% for SDFA）. The present results are the first approach on morphometric evaluation of DNA fragmentation from the SCD technique. This approach could be used for the future definition of a classification matrix surpassing the current subjective evaluation of this important sperm factor.

关键词： DNA fragmentation Halosperm morphometry principal component analysis SDFA subpopulation

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Scholz’s First Conjecture: A Brief Demonstration

引用

Applied Mathematics 2016年第1期7卷 70-76页

作者： José M. Sautto Agustín Santiago Carlos N. Bouza Veró nica Campos campus costa chica Universidad Aut&oacute noma de Guerrero Guerrero M&eacute xico Facultad de Matemá ticas Universidad Aut&oacute noma de Guerrero Acapulco M&eacute xico Facultad de Matemá tica y Computació n Universidad de la Habana Ciudad de La Habana Cuba

This paper presents a brief demonstration of Schulz’s first conjecture, which sets the upper and lower limits on the length of the shortest chain of addition. Two methods of the upper limit are demonstrated;the second one is based on the algorithm of one of the most popular methods for obtaining addition chains of a number, known as the binary method.

关键词： Addition Chain Exponentiation Short Chain Scholz’s Conjecture Binary Method

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Spermiogram and sperm head morphometry assessed by multivariate cluster analysis results during adolescence （12-18 years） and the effect of varicocele

引用

Asian Journal of Andrology 2016年第6期18卷 824-830页

作者： Fernando Vasquez Caries Soler Patricia Camps Anthony Valverde Almudena Garcia-Molina Research Group on Reproductive and Sexual Health Health Sciences Division Universidad del Norte EO. Box 1569 Barranquilla Colombia Department of Functional Biology and Physical Anthropology University of Valencia 46100 Burjassot Valencia Spain R+D Department Proiser R+D Scientific Park University of Valencia 46980 Paterna Valencia Spain Technological Institute of costa Rica Agronomy School Animal Reproduction Department San Carlos Campus 223-21001 San Carlos Costa Rica

This work evaluates sperm head morphometric characteristics in adolescents from 12 to 18 years of age, and the effect of varicocele. Volunteers between 150 and 224 months of age （mean 191, n = 87）, who had reached oigarche by 12 years old, were recruited in the area of Barranquilla, Colombia. Morphometric analysis of sperm heads was performed with principal component （PC） and discriminant analysis, Combining seminal fluid and sperm parameters provided five PCs： two related to sperm morphometry, one to sperm motility, and two to seminal fluid components. Discriminant analysis on the morphometric results of varicocele and nonvaricocele groups did not provide a useful classification matrix. Of the semen-related PCs, the most explanatory （40%） was related to sperm motility. Two PCs, including sperm head elongation and size, were sufficient to evaluate sperm morphometric characteristics. Most of the morphometric variables were correlated with age, with an increase in size and decrease in the elongation of the sperm head. For head size, the entire sperm population could be divided into two morphometric subpopulations, SP1 and SP2, which did not change during adolescence. In general, for varicocele individuals, SP1 had larger and more elongated sperm heads than SP2, which had smaller and more elongated heads than in nonvaricocele men. In summary, sperm head morphometry assessed by CASA-Morph and multivariate cluster analysis provides a better comprehension of the ejaculate structure and possibly sperm function. Morphometric analysis provides much more information than data obtained from conventional semen analysis.

关键词： adolescence CASA-Morph system seminal quality sperm head morphometry spermiogram subpopulation

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

A Two-Scale Multi-Physics Deep Learning Model for Smart MEMS Sensors

引用

Journal of Materials Science and Chemical Engineering 2021年第8期9卷 41-52页

作者： José Pablo Quesada-Molina Stefano Mariani Department of Civil and Environmental Engineering Politecnico di Milano Milano Italy Department of Mechanical Engineering Universidad de Costa Rica Rodrigo Facio Brenes Campus San José Costa Rica

Smart materials and structures, especially those bio-inspired, are often characterized by a hierarchy of length- and time-scales. Smart Micro Electro-Mechanical Systems (MEMS) are also characterized by different physical phenomena affecting their properties at different scales. Data-driven formulations can then be helpful to deal with the complexity of the multi-physics governing their response to the external stimuli, and optimize their performances. As an example, Lorentz force micro-magnetometers working principle rests on the interaction of a magnetic field with a current flowing inside a semiconducting, micro-structured medium. If an alternating current with a properly set frequency is let to flow longitudinally in a slender beam, the system is driven into resonance and the sensitivity to the magnetic field may result largely enhanced. In our former activity, a reduced-order physical model of the movable structure of a single-axis Lorentz force MEMS magnetometer was developed, to feed a multi-objective topology optimization procedure. That model-based approach did not account for stochastic effects, which lead to the scattering in the experimental data at the micrometric length-scale. The formulation is here improved to allow for stochastic effects through a two-scale deep learning model designed as follows: at the material scale, a neural network is adopted to learn the scattering in the mechanical properties of polysilicon induced by its polycrystalline morphology;at the device scale, a further neural network is adopted to learn the most important geometric features of the movable parts that affect the overall performance of the magnetometer. Some preliminary results are discussed, and an extension to allow for size effects is finally foreseen.

关键词： Machine Learning Artificial Neural Networks Polysilicon MEMS Uncer-tainty Quantification Lorentz Force Magnetometer

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Onto the sense of smell in macaws, amazons and toucans: can they use volatile cues of fruits to make foraging decisions?

引用

Integrative Zoology 2023年第4期18卷 762-771页

作者： M.Carmen HERNÁNDEZ Ana María VILLADA Isabel BARJA Unidad Zoología Departamento de BiologíaUniversidad Autónoma de MadridCampus Universitario de CantoblancoMadridSpain Toucan Rescue Ranch HerediaCosta Rica Centro de Investigación en Biodiversidad y Cambio Global(CIBC-UAM)Universidad Autónoma de Madrid MadridSpain

Over the past decades,empirical evidence has been accumulated indicating that olfactory information plays a fundamental role in bird life ***,many aspects of avian olfaction remain poorly *** purpose was to broaden the knowledge about the importance of the sense of smell in some neglected bird groups:psittaciformes and ramphastids,and to compare how the response varied between the *** of the lack of information about the use of chemical cues for locating food in fruit-eating species,we also aimed to delve into this *** conducted a 3-choice(water/vinegar/papaya and banana juice)scent test in 5 costa Rican native species:scarlet macaw(Ara macao),red-lored amazon(Amazona autumnalis),yellow-naped amazon(Amazona auropalliata),keel-billed toucan(Ramphastos sulfuratus),and yellow-throated toucan(Ramphastos ambiguus).Results revealed that macaws and toucans allocated signiﬁcantly more time to interacting with the fruit scent container,indicating that these species can perceive the volatile chemicals emitted by ripe fruits and that they can use this information to make foraging ***,amazons did not dedicate more time to interact with the fruit *** research provides theﬁrst evidence of the ability to exploit chemical volatile cues in macaws and toucans.

关键词： avian olfaction bird senses frugivorous birds psittaciformes ramphastids scent test

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Recent surface marine sediments of Cocos Island in costa Rica

引用

International Journal of Sediment Research 2014年第1期29卷 59-72页

作者： Jeffrey A.SIBAJA-CORDERO Jesús S.TRONCOSO Eddy GóMEZ-RAMíREZ Escuela de Biología&Centro de Investigación en Ciencias del Mary Limnología (CIMAR) Universidad de Costa Rica Dr.grad.by Departamento de Ecología y Biología Animal Facultad de Ciencias del MarUniversidad de Vigo Departamento de Ecología y Biología Animal Facultad de Ciencias del MarUniversidad de VigoCampus Lagoas Marcosende Centro de Investigación en Ciencias del Mary Limnología(CIMAR) Universidad de Costa RicaSan Pedro 115012 060 San JoséCosta Rica Dr.(Cand).Departamento de Biología Facultad de Ciencias del Mary AmbientalesUniversidad de Cádiz

Subtidal sediments of Isla del Coco(Cocos Island),costa Rica were described in their grain size,sorting,organic matter,and carbonates from 27 dredge samples(3-75 m),collected in April *** organic matter range between 1.37-3.31%and carbonates presented a mean of 74±17%.The sorting was moderately or *** grain size ranged between *** pattern is that sediment change from inner to mouth of *** and gravel fractions increased offshore and organic matter have high values inner the *** of vegetal debris and mud was from the rivers of this island covered with rain and cloud forest.

关键词： Sand bottom Sorting Organic matter Carbonates Isla del Coco

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：