检索结果-南通市图书馆

Population viability analysis: using a modeling tool to assess the viability of tapir populations in fragmented landscapes

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Integrative Zoology 2012年第4期7卷 356-372页

作者： em..ia Patrícia MEDICI Arnaud Leonard Jean DESBIEZ Lowland Tapir Conservation Initiative IPÊ-Institute for Ecological ResearchNazaréPaulistaSão PauloBrazil IUCN/SSC Tapir Specialist Group(TSG) GlandSwitzerland Escola Superior de Conservação Ambiental e Sustentabilidade(ESCAS/IPÊ) NazaréPaulistaSão PauloBrazil IUCN/SSC Conservation Breeding Specialist Group(CBSG) Brazil NetworkCampo GrandeMSBrazil Royal Zoological Society of Scotland EdinburghScotland

A population viability analysis(PVA)was conducted of the lowland tapir populations in the Atlantic Forest of the Pontal do Paranapanem..region,Brazil,including Morro do Diabo State Park(MDSP)and surrounding forest *** from the model projected that the population of 126 tapirs in MDSP is likely to per-sist over the next 100 years;however,200 tapirs would be required to maintain a viable ***-ity analysis showed that sub-adult mortality and adult mortality have the strongest influence on the dynamics of lowland tapir *** road-kill has a major impact on the MDSP tapir population and can lead to population *** modeling showed that dispersal of tapirs from MDSP to the surrounding fragments can be detrimental to the overall metapopulation,as fragments act as ***,the model showed that under certain conditions the maintenance of the metapopulation dynamics might be determinant for the persistence of tapirs in the region,particularly in the smaller *** establishment of corridors con-necting MDSP to the forest fragments models resulted in an increase in the stochastic growth rate,making ta-pirs more resilient to threats and catastrophes,but only if rates of mortality were not increased when using *** PVA showed that the conservation of tapirs in the Pontal region depends on:the effective protection of MDSP;maintenance and,whenever possible,enhancem..t of the functional connectivity of the landscape,reducing mortality during dispersal and threats in the unprotected forest fragments;and neutralization of all threats affecting tapirs in the smaller forest fragments.

关键词： Atlantic Forest fragmentation lowland tapir minimum viable population population viability analysis

Analytical and Computational Studies of Correlations of Hydrodynamic Fluctuations in Shear Flow

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Communications in Computational Physics 2018年第1期23卷 93-117页

作者： Xin Bian Mingge Deng George em..arniadakis Division of Applied Mathem..ics Brown UniversityProvidenceRhode Island 02912USA Lehrstuhl fur Aerodynamik und Stromungsmechanik Technische Universitat Munchen85748 GarchingGermany

We study correlations of hydrodynamic fluctuations in shear flow analytically and also by dissipative particle dynamics(DPD)*** hydrodynamic equations are linearized around the macroscopic velocity field and then solved by a perturbation method in Fourier-transformed *** autocorrelation functions(ACFs)fromthe analyticalmethod are comparedwith results obtained fromDPD simulations under the same shear-flow *** to a moderate shear rate,various ACFs from the two approaches agree with each other *** large shear rates,discrepancies between the two methods are observed,hence revealing strong additional coupling between different fluctuating variables,which is not considered in the analytical *** addition,the results at low and moderate shear rates can serve as benchmarks for developing multiscale algorithms for coupling of heterogeneous solvers,such as a hybrid simulation of molecular dynamics and fluctuating hydrodynamics solver,where thermal fluctuations are indispensable.

关键词： Hydrodynamic fluctuations correlation functions dissipative particle dynamics shear flow

Nonlocal Flocking Dynamics: Learning the Fractional Order of PDEs from Particle Simulations

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Communications on Applied Mathem..ics and Computation 2019年第4期1卷 597-619页

作者： Zhiping Mao Zhen Li George em..arniadakis Division of Applied Mathem..ics Brown UniversityProvidenceRI02912USA Pacific Northwest National Laboratory RichlandWA 99354USA

Flocking refers to collective behavior of a large number of interacting entities,where the interactions between discrete individuals produce collective motion on the large *** em..oy an agent-based model to describe the microscopic dynamics of each individual in a flock,and use a fractional partial differential equation(fPDE)to model the evolution of macroscopic quantities of *** macroscopic models with phenomenological interaction functions are derived by applying the continuum hypothesis to the microscopic *** of specifying the fPDEs with an ad hoc fractional order for nonlocal flocking dynamics,we learn the effective nonlocal influence function in fPDEs directly from particle trajectories generated by the agent-based *** dem..strate how the learning framework is used to connect the discrete agent-based model to the continuum fPDEs in one-and two-dimensional nonlocal flocking *** particular,a Cucker-Smale particle model is em..oyed to describe the microscale dynamics of each individual,while Euler equations with nonlocal interaction terms are used to compute the evolution of macroscale *** trajectories generated by the particle simulations mimic the field data of tracking logs that can be obtained *** can be used to learn the fractional order of the influence function using a Gaussian process regression model implem..ted with the Bayesian *** show in one-and two-dimensional benchmarks that the numerical solution of the learned Euler equations solved by the finite volume schem..can yield correct density distributions consistent with the collective behavior of the agent-based system..olved by the particle *** proposed method offers new insights into how to scale the discrete agent-based models to the continuum-based PDE models,and could serve as a paradigm on extracting effective governing equations for nonlocal flocking dynamics directly from particle trajectories.

关键词： Fractional PDEs Gaussian process Bayesian optimization Fractional Laplacian Conservation laws

The evaluation of gastrointestinal function in diabetic patients

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 1999年第4期5卷 5-10页

作者： Quigley em

Ｎｏｗａｄａｙｓ，ａｎｕｍｂｅｒｏｆｏｐｔｉｏｎｓａｒｅａｖａｉｌａｂｌｅｆｏｒｔｈｅａｓｅｓｍｅｎｔｏｆｇａｓｔｒｉｃｍｏｔｏｒｆｕｎｃｔｉｏｎ．Ｔｈｕｓ，ａｇｌｏｂａｌｅｖａｌｕａｔｉｏｎｏｆｇａｓｔｒｉｃｍｏｔ... 详细信息

Ｎｏｗａｄａｙｓ，ａｎｕｍｂｅｒｏｆｏｐｔｉｏｎｓａｒｅａｖａｉｌａｂｌｅｆｏｒｔｈｅａｓｅｓｍｅｎｔｏｆｇａｓｔｒｉｃｍｏｔｏｒｆｕｎｃｔｉｏｎ．Ｔｈｕｓ，ａｇｌｏｂａｌｅｖａｌｕａｔｉｏｎｏｆｇａｓｔｒｉｃｍｏｔｏｒｆｕｎｃｔｉｏｎｍａｙｂｅｏｂ...

关键词： gastrointestinal diabetic evaluation function The

Learning two-phase microstructure evolution using neural operators and autoencoder architectures

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

npj Computational Materials 2022年第1期8卷 1804-1816页

作者： Vivek Oommen Khem..j Shukla Somdatta Goswami Rémi Dingreville George em..arniadakis School of Engineering Brown UniversityProvidenceRIUSA Division of Applied Mathem..ics Brown UniversityProvidenceRIUSA Center for Integrated Nanotechnologies Sandia National LaboratoriesAlbuquerqueNM87185USA

Phase-field modeling is an effective but computationally expensive method for capturing the mesoscale morphological and microstructure evolution in ***,fast and generalizable surrogate models are needed to alleviate the cost of computationally taxing processes such as in optimization and design of *** intrinsic discontinuous nature of the physical phenomena incurred by the presence of sharp phase boundaries makes the training of the surrogate model *** develop a framework that integrates a convolutional autoencoder architecture with a deep neural operator(DeepONet)to learn the dynamic evolution of a two-phase mixture and accelerate time-to-solution in predicting the microstructure *** utilize the convolutional autoencoder to provide a compact representation of the microstructure data in a low-dimensional latent *** DeepONet is trained in the latent space,it can be used to replace the high-fidelity phase-field numerical solver in interpolation tasks or to accelerate the numerical solver in extrapolation tasks.

关键词： materials phase operators

Fractional Buffer Layers:Absorbing Boundary Conditions for Wave Propagation

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Communications in Computational Physics 2022年第2期31卷 331-369页

作者： Min Cai Ehsan Kharazmi Changpin Li George em..arniadakis Department of Mathem..ics Shanghai University99 Shangda RoadShanghai 200444P.R.China Division of AppliedMathem..ics Brown University170 Hope StProvidenceRI 02906USA School of Engineering Brown University184 Hope StProvidenceRI 02912USA

We develop fractional buffer layers(FBLs)to absorb propagating waves without reflection in bounded *** formulation is based on variable-order spatial fractional *** select a proper variable-order function so that dissipation is induced to absorb the coming waves in the buffer layers attached to the *** particular,we first design proper FBLs for the one-dimensional one-way and two-waywave ***,we extend our formulation to two-dimensional problem..wherewe introduce a consistent variable-order fractionalwave *** each case,we obtain the fully discretized equations by em..oying a spectral collocation method in space and Crank-Nicolson or Adams-Bashforth method in *** compare our results with a finely tuned perfectly matched layer(PML)method and show that the proposed FBL is able to suppress reflected waves including corner reflections in a two-dimensional rectangular *** also dem..strate that our formulation is more robust and uses less number of equations.

关键词： Variable-order fractional derivatives FBL wave equation

Body awareness therapy: A new strategy for relief of symptoms in irritable bowel syndrome patients

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2007年第23期13卷 3206-3214页

作者： em..riksson IE Mller RH Sderberg HT Eriksson GK Kurlberg Departments of Surgery Sahlgrenska University Hospital/stra Gteborg Sweden Departments of Medicine Sahlgrenska University Hospital/stra Gteborg Sweden

AIM: To compare irritable bowel syndrome (IBS) pa- tients with apparently healthy persons and to evaluate body awareness therapy, which is a physiotherapeutic rem..y focusing on normalising tensions in the body, for the treatment of IBS with the hypothesis that altered body tension is associated with the syndrome. METHODS: Twenty-one IBS patients received body awareness therapy two hours weekly for 24 wk. At base- line as well as after 12 and 24 wk, they underwent ex- aminations including resource oriented body examination in combination with body awareness scale evaluation and f illed in gastrointestinal and psychological symptom questionnaires. Saliva cortisol was analysed. A group of 21 apparently healthy persons underwent the same ex- aminations once. RESULTS: Compared to the apparently healthy group, IBS patients scored higher at baseline for gastrointestinal and psychological symptoms. They showed more often alterations in normal body tension patterns, as well as deviating cortisol slopes in saliva. After 24 wk of body awareness therapy, their gastrointestinal and psychologi- cal symptoms were reduced overall. Somatic symptoms decreased in parallel with depressive symptoms. Whole body pain score decreased, coping ability as well as bio- chem..al stress markers improved. CONCLUSION: IBS patients scored higher for gastroin- testinal and psychological symptoms, and presented with altered biochem..al stress markers. Their body tension deviated compared to healthy controls. Furthermore,body awareness therapy gave relief of both somatic com- plaints, psychological symptoms and normalised body tension. These findings indicate that distorted tension constitutes an important part of the symptoms in IBS.

关键词： Irritable bowel syndrome Pain Cortisol Physiotherapy Body awareness therapy Psychosomatics Gastrointestinal tract Stress

A novel package system..ased on an EBV replicon vector for producing high titer recombinant adeno-associated virus vector

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Science Bulletin 1997年第20期42卷 1741-1744页

作者： Yan, ZY Yao, em..hang, T Shu, YL Hou, YD Chinese Acad Prevent Med Inst Virol State Key Lab Mol Virol & Genet Engn Beijing 100052 Peoples R China

ADENO-ASSOCIATED virus (AAV) was a human parvovirus considered as a gene delivery vehiclefor human gene therapy. Recombinant AAV vector (rAAV) could mediate the foreign DNAintegration into chromosome and establish a stable expression in the infected cells. As a viraltransduction vector, rAAV was superior to the traditional retrovirus vector for its high *** pathogenicity, and capacity of infecting postmitosis cells. The current strategy for produc-

关键词： recombinant AAV vector EBV replicon vector package cell line.

Bi-Orthogonal fPINN:A Physics-Informed Neural Network Method for Solving Time-Dependent Stochastic Fractional PDEs

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

Communications in Computational Physics 2023年第9期34卷 1133-1176页

作者： Lei Ma Rongxin Li Fanhai Zeng Ling Guo George em..arniadakis Department of Mathem..ics Shanghai Normal UniversityShanghai 200234China School of Mathem..ics Shandong UniversityShandong 250100China Division of Applied Mathem..ics Brown UniversityProvidenceRI 02906USAand School of EngineeringBrown UniversityProvidenceRI 02906USA

Fractional partial differential equations(FPDEs)can effectively represent anomalous transport and nonlocal ***,inherent uncertainties arise naturally in real applications due to random forcing or unknown material *** models considering nonlocal interactions with uncertainty quantification can be formulated as stochastic fractional partial differential equations(SFPDEs).There are many challenges in solving SFPDEs numerically,especially for long-time integration since such problem..are high-dimensional and ***,we combine the bi-orthogonal(BO)method for representing stochastic processes with physicsinformed neural networks(PINNs)for solving partial differential equations to formulate the bi-orthogonal PINN method(BO-fPINN)for solving time-dependent ***,we introduce a deep neural network for the stochastic solution of the time-dependent SFPDEs,and include the BO constraints in the loss function following a weak *** automatic differentiation is not currently applicable to fractional derivatives,we em..oy discretization on a grid to compute the fractional derivatives of the neural network *** weak formulation loss function of the BO-fPINN method can overcome some drawbacks of the BO methods and thus can be used to solve SFPDEs with eigenvalue ***,the BO-fPINN method can be used for inverse SFPDEs with the same framework and same computational complexity as for forward *** dem..strate the effectiveness of the BO-fPINN method for different benchmark ***,we first consider an SFPDE with eigenvalue crossing and obtain good results while the original BO method *** then solve several forward and inverse problem..governed by SFPDEs,including problem..with noisy initial *** study the effect of the fractional order as well as the number of the BO modes on the accuracy of the BO-fPINN *** results dem..strate the flexibility and efficiency

关键词： Scientific machine learning uncertainty quantification stochastic fractional differential equations PINNs inverse problems