检索结果-南通市图书馆

维普期刊数据库

On Problems in the Calculus of Variations in Increasingly Elongated Domains

在线全文

学校读者我要写书评

暂无评论

Chinese Annals of Mathematics,Series B 2018年第2期39卷 163-182页

作者： herve LE DRET Amira MOKRANE Dedicated to Philippe G. Ciarlet on the occasion of his 80th birthda

This paper deals with minimization problems in the calculus of variations set in a sequence of domains, the size of which tends to infinity in certain directions and such that the data only depend on the coordinates in the directions that remain constant. The authors study the asymptotic behavior of minimizers in various situations and show that they converge in an appropriate sense toward minimizers of a related energy functional in the constant directions.

关键词： Calculus of variations Domains becoming unbounded Asymptotic behaviorExponential rate of convergence

维普期刊数据库

Effects of fluctuating thermal regimes on cold survival and life history traits of the spotted wing Drosophila(Drosophila suzukii)

在线全文

学校读者我要写书评

暂无评论

Insect Science 2020年第2期27卷 317-335页

作者： Thomas Enriquez David Ruel Maryvonne Charrier herve Colinet CNRS ECOBIO-UMR 6553Universite de RennesRennesFrance Department of Entomology The Robert H.Smith Faculty of AgricultureFood and EnvironmentThe Hebrew University of JerusalemPO 12Rchovot 76100Isael

Drosophila suzukii is an invasive pest causing severe damages to a large panel of cultivated *** facili tate its biocontrol with stratcgies such as sterile or incompatible insect techniques,*** must be mass-produced and then stored and transported under low *** cold exposure induces chill injuries that can be mitigated if the cold period is interrupted with short warming intervals,referred to as fluctuating thermal regimes(FTR).In this study,we tested how to optimally use FTR to extend the shelf life of *** under cold *** FTR parameters were asessed:temperature(15,20,25℃),duration(0.5,1,2,3 h),and frequency(every 12,24,36,48 h)of warming intervals,in two wild-type lines and in two developmental stages(pupac and adults).Generally,FTR improved cold storage tolerance with respect to constant low temperatures(CLT).Cold mortality was lower when recovery temperature was 20℃ or higher,when duration was 2 h per day or longer,and when warming interruptions occurred frequently(every 12 or 24 h).Applying an optimized FTR protocol to adults greatly reduced cold mortality over long-term storage(up to 130 d).Consequences of FTR on fitness-related traits were also *** adults,poststorage survival was unaffected by FTR,as was the case for female fecundity and male mating *** the other hand,when cold storage occurred at pupal stage,postorage survival and male mating capacity were altered under CLT,but not under *** storage of pupae,female fecundity was lower under FTR compared to CLT,suggesting an energy trade-off between repair of chill damages and C22 *** study provides detailed information on the application and optimization of an FTR-based protocol for cold storage of *** that could be useful for the biocontrol of this pest.

关键词： cold storage fluctuating thermal regines lfe-history traits recovery sotted wing drosophila

The transcriptomic signature of responses to larval crowding in Drosophila melanogaster

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Insect Science 2023年第2期30卷 539-554页

作者： Juliano Morimoto Marius wenzel Davina Derous Youn Henry herve Colinet School of Biological Sciences University of AberdeenAberdeenUnited Kingdom Programa de Pos-graduacao em Ecologia e Conservacao Universidade Federal do ParanaCuritibaBrazil Institute of Mathematics King's CollegeUniversity of AberdeenAberdeenUnited Kingdom CNRS ECOBIO(Ecosystemesbiodiversiteévolution)—UMR 6553University of RennesRennesFrance Department of Ecology and Evolution University of LausanneLausanneSwitzerland

Intraspecific competition at the larval stage is an important ecological factor affecting life-history,adaptation and evolutionary trajectory in holometabolous ***,the molecular pathways underpinning these ecological processes are poorly *** reared Drosophila melanogaster at three egg densities(5,60,and 300 eggs/mL)and sequenced the transcriptomes of pooled third-instar *** also examined emergence time,egg-to-adult viability,adult mass,and adult sex-ratio at each *** crowding had minor detrimental effects on adult phenotypes compared to low density and yielded 24 differentially expressed genes(DEGs),including several chitinase *** contrast,high crowding had substantial detrimental effects on adult phenotypes and yielded 2107 *** these,upregulated gene sets were enriched in sugar,steroid and amino acid metabolism as well as DNA replication pathways,whereas downregulated gene sets were enriched in ABC transporters,taurine,Toll/Imd signaling,and P450 xenobiotics metabolism ***,our findings show that larval crowding has a large consistent effect on several molecular pathways(i.e.,core responses)with few pathways displaying density-specific regulation(i.e.,idiosyncratic responses).This provides important insights into how holometabolous insects respond to intraspecific competition during development.

关键词： intraspecific competition larval crowding life-history trade-offs transcriptomics

Optimizing widths with PSO for center selection of Gaussian radial basis function networks

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2014年第5期57卷 86-102页

作者： ZHAO ZhongQiu wU XinDong LU CanYi GLOTIN herve GAO Jun College of Computer Science and Information Engineering Hefei University of Technology Department of Computer Science University of Vermont Hefei Institute of Intelligent Machines Chinese Academy of Sciences Department of Automation University of Science and Technology of China

The radial basis function(RBF)centers play different roles in determining the classification capability of a Gaussian radial basis function neural network(GRBFNN)and should hold different width ***,it is very hard and time-consuming to optimize the centers and widths at the same *** this paper,we introduce a new insight into this *** explore the impact of the definition of widths on the selection of the centers,propose an optimization algorithm of the RBF widths in order to select proper centers from the center candidate pool,and improve the classification performance of the *** design of the objective function of the optimization algorithm is based on the local mapping capability of each Gaussian ***,in the design of the objective function,we also handle the imbalanced problem which may occur even when different local regions have the same number of ***,the recursive orthogonal least square(ROLS)and genetic algorithm(GA),which are usually adopted to optimize the RBF centers,are separately used to select the centers from the center candidates with the initialized widths,in order to testify the validity of our proposed width initialization strategy on the selection of *** experimental results show that,compared with the heuristic width setting method,the width optimization strategy makes the selected centers more appropriate,and improves the classification performance of the ***,the GRBFNN constructed by our method can attain better classification performance than the RBF LS-SVM,which is a state-of-the-art classifier.

关键词： GRBFNN RBF widths objective function generalization capability particle swarm optimization

Chemical composition, antiproliferative, antioxidant and antibacterial activities of essential oils from aromatic plants growing in Sudan

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Asian Pacific Journal of Tropical Medicine 2016年第8期9卷 741-748页

作者： Sakina Yagi Randa Babiker Tzvetomira Tzanova herve Schohn Department of Botany Faculty of Science University of Khartoum Department of Botany Faculty of Science University of Kordofan Universite de Lorraine-UMR CNRS 7565-Structure et Reactivite des Systemes Moleculaires Complexes-Campus Bridoux-rue du General Delestraint57070 Metz Cedex

Objective: To explore the potential of essential oil, as therapeutic molecule source, from olibanum of Boswellia papyrifera(Burseraceae), leafy stems of Cymbopogon schoenanthus(Poaceae) and Croton zambesicus(Euphorbiaceae) and rhizome of Cyperus rotundus(Cyperaceae) found in Sudan. Respective essential oil was evaluated for antiproliferative, antibacterial and antioxidant activity. Methods: Essential oils were extracted by hydrodistillation and then analysed by gas chromatography coupled to mass spectrometry(GCMS). Anti-proliferative activity was determined against human cell lines(MCF7 and MDAMB231, HT29 and HCT116) by the thiazolyl blue tetrazolium bromide(MTT) procedure. Antioxidant activity was evaluated by diphenyl 2 pycril hydrazil(DPPH) assay. Antibacterial activity was determined against two Gram-positive and two Gram-negative bacteria by microdilution method. Results: The essential oil from olibanum of Boswellia papyriferacontained mainly alcohol and ester derivatives(46.82%) while monoterpenes(69.84%) dominated in Corton zambesicus oil. Sesquiterpenes were the most highly represented classes of terpene derivatives in Cyperus schoenanthus(71.59%) and Cyperus rotundus(44.26%). Oil of Cymbopogon schoenanthus revealed the best anti-proliferative activity against HCT116 cell line with IC50 value at(19.1 ± 2.0) μg/m L. Oil of Croton zambesicus showed the best antioxidant activity [EC50(4.20 ± 0.19) mg/m L]. All oils showed good antibacterial activity against Escherichia coli, Bacillus subtilis and Staphylococcus aureus with minimum inhibitory concentration(MIC) value ranged from 16 to 250 μg/m L. Conclusions: The results suggest that the essential oils of these plants could be used as a source of natural anti-proliferative, antioxidant and antibacterial agents.

关键词： Boswellia papyrifera Croton zambesicus Cymbopogon schoenanthus Cyperus rotundus GC/MS profile anti-proliferative activity

Impact of nanocrystallinity segregation on the growth and morphology of nanocrystal superlattices

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nano Research 2013年第8期6卷 611-618页

作者： Yanfen wan herve Portals Nicolas Goubet Alain Mermet Marie-Paule Pileni Université Pierre et Marie Curie Paris 6 UMR 7070 LM2N 8P 52 4 place Jussieu 75005 Paris France Centre National de la Recherche Scientifique Unitd Mixte de Recherche 7070 LM2N 4 place Jussieu 75005 Paris France Université Lyon I Institut Lumiére Matiére Unité Mixte de Recherche 5306 CNRS Bāt. A. Kastler 10 rueAda Byron 69622 Villeurbanne France

A colloidal solution of 5 nm Au tetradecanethiol-coated nanoparticles is syn-thesized. After fast evaporation of one drop, ordered monolayers both composed of single domain and polycrystalline nanocrystals are obtained. On increasing the amount of materials and the evaporation time, nanocrystal films with irregular outlines are produced together with close-packed 3D superlattices exhibiting a truncated-tetrahedral shape. Using low-frequency micro-Raman scattering spectroscopy and electron microscopy the building block nanocrystallinity is characterized. Spontaneous nanocrystallinity segregation is revealed： the truncated-tetrahedral supracrystals are shown to mainly contain single domain building blocks while the supracrystalline films are composed of a mixture of single domain and polycrystalline nanocrystals. This observation points out the correlation between the nanocrystallinity segregation involved in the growth of the nanocrystal superlattices and their morphology.

关键词： supracrystals close-packed self-assembly metal nanoparticles Raman scatteringspectroscopy

The Interaction Between Structure and Soil on Fixed Oil Platforms Installed on Very Soft Soil

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

The Interaction Between Structure and Soil on Fixed Oil Plat...

作者： NDAYE MUDUMBI herve 中国石油大学(北京)

学位级别：硕士

Marine environment is considered a complicated environment because it consist of several physical variables that can affect its ability to support the stability of offshore fixed structures and *** issues of soft foundation soils,presence of gas layers,and low temperatures affect the geotechnical stability parameters of the foundation soil,thus its inability to maintain the stability of fixed *** the bearing capacity of the soil for fixed structure stability,the influence of currents and tides of shallow water pose a significant threat to fixed offshore *** address all these problems is quite challenging,especially the difficulties in keeping certain physical and geomechanical parameters of the foundation soil constant when modelling the problem because of the very soft nature of the soil,its heterogeneity,and the tendency of being *** thesis intends to model these problems and investigate how they affect the bearing capacity of a soft soil in *** order to analyse this problem,we had to first determine the distribution of stresses and strains induced in the soil and the soil’s bearing capacity by using the Mohr’s failure ***,by developing the equation of the second laws of thermodynamics,the temperature profile of different soil layers is determined as a function of depth,and to study the influence of low soil temperatures on the fluid contained in the pore volume of the ***,a study of the influence of the presence of a gas layer on the mechanical properties and the state of cohesion of the soil of the foundation was also carried ***,by the movement of the waters in a shallow marine environment,we had to study the dynamics of the forces of the tide of the waters on the *** following results were obtained in this work: 1)Soil layers with low values of friction angle,frictional force,cohesive force and Young’s modulus are considered as very soft *** soil layers with hig

关键词：

Animal phylogeny and large-scale sequencing： progress and pitfalls

同方学位论文库评论

在线全文

同方学位论文库

学校读者我要写书评

暂无评论

植物分类学报 2008年第3期46卷 274-286页

作者： Henner BRINKMANN herve PHILIPPE Centre Robert Cedergren Departement de Biochimie Universite de Montreal 2900 Boulevard Edouard-Montpetit Montreal Quebec H3TIJ4 Canada

Phylogenomics, the inference of phylogenetic trees using genome-scale data, is becoming the rule for resolving difficult parts of the tree of life. Its promise resides in the large amount of information available, which should eliminate stochastic error. However, systematic error, which is due to limitations of reconstruction meth-ods, is becoming more apparent. we will illustrate, using animal phylogeny as a case study, the three most effi-cient approaches to avoid the pitfalls of phylogenomics: (1) using a dense taxon sampling, (2) using probabilistic methods with complex models of sequence evolution that more accurately detect multiple substitutions, and (3) removing the fastest evolving part of the data (e.g., species and positions). The analysis of a dataset of 55 animal species and 102 proteins (25712 amino acid positions) shows that standard site-homogeneous model inference is sensitive to long-branch attraction artifact, whereas the site-heterogeneous CAT model is less so. The latter model correctly locates three very fast evolving species, the appendicularian tunicate Oikopleura, the acoel Convoluta and the myxozoan Buddenbrockia. Overall, the resulting tree is in excellent agreement with the new animal phylogeny, confirming that "simple" organisms like platyhelminths and nematodes are not necessarily of basal emergence. This further emphasizes the importance of secondary simplification in animals, and for organismal evolution in general.

关键词：动物发展史测序方法缺陷改进措施

维普期刊数据库

The Impact of Credit Risk Management on Commercial Panks Performance in Democratic Republic of the Congo. Case of BCDC,ECOBANK,RAwBANK and TMB

在线全文

学校读者我要写书评

暂无评论

The Impact of Credit Risk Management on Commercial Panks Per...

作者： KINKANI BATEKELE herve LANDRY 华中师范大学

学位级别：硕士

Credit risk is a major concern for banks,bond issuers and *** may be due to an economic recession,thus putting the borrowers in the impossibility of meeting their commitments,but it is all the more crucial for the banker to find effective ways to protect themselves,if not to master this risk of Non-reimbursement of the customer,synonymous with loss or *** is utopian for a company to have the goal of losing *** all companies,the bank is a commercial company,which also seeks to maximize its *** therefore has to be profitable in its *** is an anticipation of future revenue,so its good management is crucial to the performance and sustainability of the *** performance of a bank implies a good management of credit risks by effective techniques *** of the biggest activities of commercial banks in the Democratic Republic of the Congo is the granting of bank *** credit-granting activity creates risks and the credit risk is the most *** is therefore important that this credit risk be managed prudently to avoid its negative effects on the profitability of *** main objective of this study was to find the impact of credit risk management on the financial profitability of the Congo’s commercial *** specific objectives were to find the effects of CAR and NPLR on the performance of commercial *** this study,we considered independent variables the CAR and NPLR while the dependent variables were ROE and *** used commercial banks in the Democratic Republic of the Congo as a study population,and as a sample the four largest banks in the period from 2009 to *** was diagnosed for and treated,where necessary,of the problems of panel *** a fixed effects model specification a panel Estimate Generalized Least Squares regression was done on the data using E views *** a 5%non-directional test of hypothesis,the study found a capital adequacy ratio has statistica

关键词：