检索结果-南通市图书馆

Experimental measurements of gamma-photon production and estimation of electron/positron production on the PETAL laser facility

引用

Matter and Radiation at Extremes 2024年第5期9卷 32-47页

作者： F.brun L.Ribotte G.boutoux X.Davoine P.E.Masson-Laborde Y.Sentoku n.Iwata n.blanchot D.batani I.Lantuéjoul L.Lecherbourg b.Rosse C.Rousseaux b.Vauzour D.Raffestin E.D’Humières X.Ribeyre Centre Lasers Intenses et Applications UMR 5107Universitéde Bordeaux-CNRS-CEA33405 TalenceFrance CEA DAMCESTAF-33116 Le BarpFrance CEA DAMDIFF-91297 ArpajonFrance CEA LMCEUniversitéParis-Saclay91680 Bruyères-le-ChâtelFrance Institute of Laser Engineering Osaka University2-6 YamadaokaSuitaOsaka 565-0871Japan

This article reports the first measurements of high-energy photons produced with the high-intensity PETawatt Aquitaine Laser(PETAL)*** experiments were performed during the commissioning of the *** laser had an energy of about 400 J,an intensity of 8×10^(18)W cm^(−2),and a pulse duration of 660 fs(FWHM).It was shot at a 2 mm-thick solid tungsten *** high-energy photons were produced mainly from the bremsstrahlung process for relativistic electrons accelerated inside a plasma generated on the front side of the *** paper reports measurements of electrons,protons and *** electrons up to35 MeV with a few-MeV temperature were recorded by a spectrometer,called SESAME(SpectreÉlectronS Angulaire MoyenneÉnergie).K-and L-shells were clearly detected by a photon spectrometer called SPECTIX(Spectromètre PetalàCristal en TransmIssion pour le rayonnnement X).High-energy photons were diagnosed by CRACC-X(Cassette de RAdiographie Centre Chambre-rayonnement X),a bremsstrahlung *** cannon analysis is strongly dependent on the hypothesis adopted for the spectral *** shapes can exhibit similar reproductions of the experimental *** eliminate dependence on the shape hypothesis and to facilitate analysis of the data,simulations of the interaction were *** model the mechanisms involved,a simulation chain including hydrodynamic,particle-in-cell,and Monte Carlo simulations was *** simulations model the preplasma generated at the front of the target by the PETAL laser prepulse,the acceleration of electrons inside the plasma,the generation of MeV-range photons from these electrons,and the response of the detector impacted by the energetic photon *** this work enabled reproduction of the experimental *** high-energy photons produced have a large emission angle and an exponential distribution *** addition to the analysis of the photon spectra,positron production was also ***,if high

关键词： process. positron hypothesis

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

brain Tumor Retrieval in MRI Images with Integration of Optimal Features

引用

Journal of Harbin Institute of Technology(new series) 2024年

作者： n V Shamna b Aziz Musthafa Department of Computer Science and Engineering， P A College of Engineering Department of Computer Science and Engineering， bearys Institute of Technology

This paper presents an approach to improve medical image retrieval， particularly for brain tumors， by addressing the gap between low-level visual and high-level perceived contents in MRI， X-ray， and CT scans. Traditional methods based on color， shape， or texture are less effective. The proposed solution uses machine learning to handle high-dimensional image features， reducing computational complexity and mitigating issues caused by artifacts or noise. It employs a genetic algorithm for feature reduction and a hybrid residual Unet (HResUnet) model for region-of-interest (ROI) segmentation and classification， with enhanced image preprocessing. The study examines various loss functions， finding that a hybrid loss function yields superior results， and the GA-HResUnet model outperforms the HResUnet. Comparative analysis with state-of-the-art models shows a 4% improvement in retrieval accuracy.

关键词：

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

引用

Current Zoology 2024年第1期70卷 1-12页

作者： Lucia V.Sommaro Juan J.Martinez Marina b.Chiappero Andrea R.Steinmann Cristina n.Gardenal JoséW.Priotto Laboratorio de Ecologia Evolutiva y biogeografia Instituto de Ecorregiones Andinas(INECoA)Universidad Nacional de Jujuy-Consejo Nacional de Investigaciones Cientificas y Tecnicas(CONICET)San Salvador de JujuyJujuyArgentina Instituto de Diversidad y Ecologia Animal(IDEA) Consejo Nacional de Investigaciones Cientificas y Técnicas(CONICET)and Universidad Nacionalde CordobaCordobaArgentina Catedra de Genética de Poblaciones y Evolucion Facultad de Ciencias ExactasFisicas y NaturalesUniversidad Nacional de CordobaCordobaArgentina Grupo de Investigaciones en Ecologia Poblacional y Comportamental(GIEPCO) Instituto de Ciencias de la TierraBiodiversidad y Ambiente(ICBiA)Universidad Nacional de Rio Cuarto-Consejo Nacional de Investigaciones Cientificas y Técnicas(CONICET)Rio CuartoCordobaArgentina

The sex-biased dispersal and kinship dynamics are important factors shaping the spatial distribution of individuals and are key parameters affecting a variety of ecological and evolutionary ***,we studied the spatial distribution of related individuals within a population of corn mice Calomys musculinus in a seasonal cycle to infer dispersal *** sampling was carried out from spring 2005 to winter 2006 in field borders of intensively managed *** data from 346 individuals with 9 microsatellites showed spatial genetic structure was weak for males,but not for *** results indicate a complex spatial kinship dynamic of related females across all ***,contrary to our expectations,dispersal distances decrease with the increase of the population ***,male dispersal distances were greater when population abundance increased and thus the availability of active *** disperse greater distances to mate and sire offspring with distant females as a possible inbreeding avoidance *** study shows that *** is capable of much greater scattering distances than previously reported and that dispersal occurs fluidly and without barriers across the *** indirect benefit of dispersal on individual fitness could be related to relaxing the competition in the natal area and increasing the mating *** study highlights the value of combining genetic relatedness,fieldwork observations,and behavioral data to estimate dispersal at a fine geographical scale.

关键词： dispersal distances kinship dynamics microsatellite small mammals spatial autocorrelation

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

EP Aquarii:A new Picture of the Circumstellar Envelope

引用

Research in Astronomy and Astrophysics 2024年第3期24卷 83-105页

作者： Pham T.nhung Do T.Hoai Pierre Darriulat Pham Tuan-Anh Pham n.Diep nguyen b.ngoc Tran T.Thai Department of Astrophysics Vietnam National Space CenterVietnam Academy of Science and Technology18Hoang Quoc VietNghia DoCau GiayHa Noivietnam

new analyses of earlier ALMA observations of oxygen-rich AGb star EP Aquarii are presented,which complete a previously published analysis and offer a different interpretation of the morpho-kinematics of the circumstellar *** birth of the equatorial density enhancement(EDE)is shown to occur very close to the star where evidence for rotation has been *** to the star and where outflows have been observed:their interaction with the gas of the nascent EDE is seen to play an important role in the development of the wind and the evolution of its radial velocity from 8 to 10 km s^(-1) on the polar symmetry axis to~2 km s^(-1) at the *** implies complex morpho-kinematics:making reliable interpretations with reasonable confidence is *** particular,it questions an earlier interpretation implying the presence of a white dwarf companion orbiting the star at an angular distance of -0″4 from its *** proposes instead an interpretation in terms of a standard mass ejection associated with a shock wave leaving a void of emission in its *** Doppler velocity wings are seen to consist of two components,the upper velocity end of the global wind,reaching above±12 km s^(-1),and an effective line broadening,confined within 200 mas from the center of the star,reaching above±20 km s^(-1) and interpreted as caused by the pattern of shock waves resulting from the interaction between stellar pulsation and convective cell partition.

关键词： stars AGb and post-AGb-(stars) circumstellar matter-radio lines stars

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Efficient guiding and focusing of intense laser pulse using periodic thin slits

引用

Matter and Radiation at Extremes 2024年第4期9卷 29-39页

作者： L.Xu T.W.Huang K.Jiang C.n.Wu H.Peng P.C.hen R.Li H.b.Zhuo C.T.Zhou Shenzhen Key Laboratory of Ultraintense Laser and Advanced Material Technology Center for Intense Laser ApplicationTechnologyand College of Engineering PhysicsShenzhen Technology UniversityShenzhen 518118People’s Republic of China

Slits have been widely used in laser-plasma interactions as plasma optical components for generating high-harmonic light and controlling laser-driven particle ***,we propose and demonstrate that periodic thin slits can be regarded as a new breed of optical elements for efficient focusing and guiding of intense laser *** fundamental physics of intense laser interaction with thin slits is studied,and it is revealed that relativistic effects can lead to enhanced laser focusing far beyond the pure diffractive focusing *** addition,the interaction of an intense laser pulse with periodic thin slits makes it feasible to achieve multifold enhancement in both laser intensity and energy transfer efficiency compared with conventional *** results provide a novel method for manipulating ultra-intense laser pulses and should be of interest for many laser-based applications.

关键词： laser pulse intense

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

Artificial enhancement of sturgeon stock in freshwater reservoirs:A case study on sterlet Acipenser ruthenus of the Kama reservoir

引用

Aquaculture and Fisheries 2024年第2期9卷 287-294页

作者： Pavel b.Mikheev Semyon n.Kazarinov Alla G.Melnikova Stanislav V.Ponosov nikolai G.Petrenko Andrei I.nikiforov Alexey Yu Puzik Olga n.Elchenkova Perm State national Research University Perm614990Russia Khabarovsk branch of the Federal State budget Scientific Institution“Russian Federal Research Institute of Fisheries and Oceanography”“KhabarovsknIRO” Khabarovsk680038Russia Perm branch of the Federal State budget Scientific Institution“Russian Federal Research Institute of Fisheries and Oceanography”“PermnIRO” Perm614991Russia Federal State budget Scientific Institution“Russian Federal Research Institute of Fisheries and Oceanography”“VnIRO” Moscow117454Russia Moscow State Institute of International Relations(University)of the Ministry for Foreign Affairs of Russia“MGIMO” Moscow117454Russia Department of State Control Supervision and Protection of Aquatic Biological Resources for Perm KraiMiddle-Volga Regional Office of the Federal Fishery AgencyPerm614990Russia

The paper presents the results of the sterlet sturgeon Acipenser ruthenus reintroduction into the Kama Reservoir(Perm Krai,Russia)by sterlet fry from hatcheries into the reservoir since *** effectiveness of hatchery releases was evaluated by monitoring gillnet sampling *** results showed that the species was reported throughout entire Kama Reservoir,which contrasts with 1988-1994 data,when the species was registered only at the upper part of the reservoir near the Kama River *** highest number and biomass values of catch per unit effort(CPUE)of the sterlet were found in submerged river channels-the deepest habitats with flow conditions which are close to the ecological requirements of the *** distribution of the sterlet within the channel biotopes of the reservoir is defined by reduced *** biggest individuals and the widest size range of the sterlet were typical for the upper area of the reservoir and Chusovskoy bay,which have the greatest *** smallest sizes were typical for fish from catches near the dam of the reservoir,which is consistent with the published data on the distribution of sterlet in reservoir *** presented results may indicate the artificial formation of the sterlet stock in the Kama Reservoir maintained by hatchery *** revealed distribution of the sterlet in the reservoir determines the direction of further research on natural reproduction and thus formation of an artificially formed ***,future studies are required to assess the possibility of hybridization of the sterlet of artificial origin with natural populations of the species,since the low genetic diversity of the sterlet released into the Kama Reservoir which can lead to irreversible loss of genetic individuality of the natural stocks of the species in the catchment of upper course of the Kama River.

关键词： Sterlet Acipenser ruthenus Kama reservoir Hatchery releases CPUE Artificial stock formation

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 FLEXIbLE ObJECTIVE-COnSTRAInT APPROACH AnD A nEW ALGORITHM FOR COnSTRUCTInG THE PARETO FROnT OF MULTIObJECTIVE OPTIMIZATIOn PRObLEMS

引用

Acta Mathematica Scientia 2024年第2期44卷 702-720页

作者： n.HOSEInPOOR M.GHAZnAVI Faculty of Mathematical Sciences Shahrood University of TechnologyShahroodIran

In this article, a novel scalarization technique, called the improved objective-constraint approach, is introduced to find efficient solutions of a given multiobjective programming problem. The presented scalarized problem extends the objective-constraint problem. It is demonstrated that how adding variables to the scalarized problem, can lead to find conditions for (weakly, properly) Pareto optimal solutions. Applying the obtained necessary and sufficient conditions, two algorithms for generating the Pareto front approximation of bi-objective and three-objective programming problems are designed. These algorithms are easy to implement and can achieve an even approximation of (weakly, properly) Pareto optimal solutions. These algorithms can be generalized for optimization problems with more than three criterion functions, too. The effectiveness and capability of the algorithms are demonstrated in test problems.

关键词： multiobjective optimization Pareto front scalarization objective-constraint approach proper efficient solution

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Advancements in assessing soil health through functional traits and energy flow analysis of soil

引用

Soil Ecology Letters 2024年第2期6卷 21-30页

作者： Jingnan Zhang Shiyu Li Elly Morrien neil b.McLaughlin Shixiu Zhang School of Life Sciences Zhengzhou UniversityZhengzhou 450001China State Key Laboratory of black Soils Conservation and Utilization Northeast Institute of Geography and AgroecologyChineseAcademy of SciencesChangchun 130012China Key Laboratory of Mollisols Agroecology Northeast Institute of Geography and AgroecologyChinese Academy of SciencesChangchun 130012China Institute of biodiversity and Ecosystem Dynamics(IbED-ELD) Department of Ecosystem and Landscape DynamicsUniversity of AmsterdamScience Park 9041098 XHA msterdamThe Netherlands Ottawa Research and Development Centre Agriculture and Agri-Food CanadaOttawa K1AoC6Canada University of Chinese Academy of Sciences Bejing 100049China

We examined the development of soil nematodes ecological indices from the perspective off *** found that soil nematode energy flow analyses based on multiple functional traits quantify the dynamics of energy flow across multipletrophic levels to provide a more comprehensive *** conducted comparative analyses of the sensitivities of nMF and energy flow to verify that the energy flow analyses are more sensitive and have greater potential to reveal soil health and ecosystem *** in-depth studies of functional traits and energy flow analysis can help us achieve informed soil management practices,sustainable agriculture,*** Tess CT nematode ecological index based on functional traits:MI El,S,bI,C1 nMF bongen.1990 Ferrisetal,2001 Ferris,2010 energs low analysis of soil nematodes Compare thecological index(nMf)and bacterivores(ba)Functional traits Energy flux Fungihores(Fn)rahn Soilnematodes latitude Lindicator Plant-parasites(PP)PF Energflus Soilhealth Omnivores-predators(oP)latitude Energy flow analysis of soil nematodes:by quantifying energy fux among trophic groups barbes et al.,2014,2018 This paper examines the development of ecological indices for soil nematodes from the perspective of functional *** emphasizes the increasing significance of integrating multiple functional traits to achieve a more accurate assessment of soil *** indices based on life history strategies,feeding habits,and body size provide useful tools for assessing soil ***,these indices do not fully capture the dynamics ofenergyflow across multiple-trophic levels inthesoil foodweb,which is critical fora deeperunderstanding of the intrinsic properties of soil *** combining functional traits such as functional group,body size,feeding preference and metabolic rate,nematode energy flow analyses provide a more comprehensive *** approach establishes a direct correlation between changes

关键词： soil nematodes soil health nematodefoodweb functional traits energyflux

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

Old-growth mixed dipterocarp forests show variable losses and gains in aboveground biomass and standing carbon over forty years

引用

Forest Ecosystems 2024年第1期11卷 14-23页

作者： Sisira Ediriweera Champika bandara Tithira Lakkana Shanika Jayasinghe David Woodbury Arun Dayanandan b.M.P.Singhakumara Xiangcheng Mi I.A.U.n.Gunatilleke C.V.S.Gunatilleke Mark SAshton Department of Science and Technology Uva Wellassa UniversityBadullaSri Lanka The Forest School Yale School of the EnvironmentYale UniversityNew HavenCT06511USA Department of Forestry and Environmental Science University of Sri JayewardenepuraNugegodaSri Lanka State Key Laboratory of Vegetation and Environmental Change Institute of BotanyChinese Academy of SciencesBeijing100093China botany Department University of PeradeniyaPeradeniyaSri Lanka

background:no studies have documented long-term trends in aboveground biomass(AGb)for mixed-dipterocarp forests(MDF),the dominant rain forest type in tropical wet equatorial *** our study,we sought to document such trends over forty years across three sites representing lowland to lower montane ***:To do this,we established fifty 100 m×25 m plots in 1978 across three sites sampled along an elevation gradient,identified as mature old-growth *** measured trees for diameter at breast height that we identified to species and *** took wood samples to calculate species wood-specific *** re-measured plots in 1998 and again in ***:We show standing AGb for all sites combined to be 517.52 Mg·ha^(-1)in 1978,but this declined by 17%over 40 years to 430.11 Mg·ha^(-1).no differences exist among sites in AGb primarily because of considerable within site variation;but interactions of time with site show declines across sites were not uniform,one remained about the *** few species represented a high proportion of the AGb with the top five species comprising between 34%and 65%,depending upon site and year *** species,Mesua nagassarium,represented a disproportionately large amount of AGb and decline over time,particularly at the low elevation ***:Our results are directly relevant to estimating AGb and standing carbon sequestered in *** study is the first to demonstrate varying but overall,declining trends in amounts of AGb among forests making predictions of biomass and standing carbon in MDF difficult over wide regions.

关键词： Western ghats Shorea spp. Southeast Asia Sri Lanka Tropical rain forest Wood specific gravity

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Contributions to the knowledge of Antarctodon sobrali(Mammalia:Astrapotheria)from the Eocene of Antarctica

引用

Advances in Polar Science 2024年第1期35卷 48-62页

作者： Javier n.GELFO Consejo nacional de Investigaciones Científicasy Técnicas(COnICET) Buenos Aires C1425FQBArgentina División Paleontología Vertebrados Museo de La PlataFacultad de Ciencias Naturales y Museo de La PlataUniversidad Nacional de La PlataLa Plata B1900FWAArgentina

The Astrapotheria constitutes one of the five orders of extinct South American native ungulates,with a fossil record that also extends to the Eocene of the Antarctic *** contrast to the abundant specimens known for litoptern Sparnotheriodontidae and metatherians,astrapotheres are represented by scant remains assigned to the endemic Antarctodon sobrali and indeterminate astrapotheres,restricted to levels 35C_(u0)and 35n of the Cucullaea I Allomember of the La Meseta *** discovery of alower molar assignable to this species in the Eocene levels of Seymour(Marambio)Island,enables a revision of the diagnosis and the homologies of the dental characters used to describe this taxon.A reanalysis of its phylogenetic relationships reveals the nearly simultaneous presence of basal astrapotheres in the early Eocene of Itaboraí(brazil),Patagonia,and West *** taxa are characterized by lacking dental specializations usually associated with more abrasive diets like terminal forms of Uruguaytheriinae and *** appears to have thrived on the Antarctic continent during the Early Eocene Climatic Optimum within the paleoclimatic context of a hot-house *** present conditions in Antarctica where no terrestrial mammals inhabit,the early Eocene climate was characterized by warmer temperatures and a biologically diverse environment rich in primary producers,dominated by nothofagus forests,encompassing both deciduous and evergreen forests,which supported a diverse assemblage of continental vertebrates.

关键词： Astrapotheria Antarctodon Eocene Seymour Island La Meseta Formation

来源：

维普期刊数据库

同方期刊数据库

同方期刊数据库评论

在线全文

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：