检索结果-南通市图书馆

review of the dynamic stiffness method for free-vibration analysis of beams

在线全文

学校读者我要写书评

暂无评论

Transportation Safety and Environment 2019年第2期1卷 106-116页

作者： j.r.Banerjee Department of Mechanical Engineering and Aeronautics School of MathematicsComputer Science and EngineeringCityUniversity of LondonLondonEC1V 0HBUnited Kingdom

The application of the dynamic stiffness method(DSM)for free-vibration analysis of beams is surveyed in this *** historical development of the DSM,which has taken place in several stages,is discussed in detail with reference to the free-vibration problems of *** particular,the suitability of the DSM in solving the free-vibration problems of beams through the application of the well-known Wittrick–Williams algorithm as a solution technique is *** literature concerning homogeneous isotropic metallic beams,for which the DSM is well established,is reviewed first,after which,with the rapid and ongoing emergence of advanced composite materials,the development of the DSM in solving the free-vibration problems of anisotropic beams is *** free-vibration analysis of functionally graded beams using the DSM is also *** survey covers the DSM application for free-vibration analysis of a wide range of beams,including sandwich beams,rotating beams,twisted beams,moving beams and bending-torsion coupled beams,amongst *** aspects of the contributions made by the author and his research team are also ***,the future potential of the DSM in solving complex engineering problems is projected.

关键词： dynamic stiffness method Wittrick-Williams algorithm free-vibration analysis

Options for reducing the negative effects of nitrogen in agriculture

在线全文

学校读者我要写书评

暂无评论

Science China(Life Sciences) 2005年第z2期48卷 861-870页

作者： j.r.Freney CSIrO Plant Industry G.P.O.Box 1600 CanberraA.C.T.2601Australia

After addition to farms by fertilizer, crop residues, biological fixation and animal excreta, nitrogen can be lost through gaseous emission, runoff and leaching to contaminate the atmosphere and water bodies, and cause adverse health effects. The efficiency of fertilizer nitrogen can be increased and losses reduced, by matching supply with crop demand, optimizing split application schemes, changing the form to suit the conditions, and use of slow-release fertilizers and inhibitors. In addition, agronomic practices such as higher plant densities, weed and pest control and balanced fertilization with other nutrients can also increase efficiency of nitrogen use. Efficiency of use by animals can be increased by diet manipulation. Feeding dairy cattle low degradable protein and high starch diets, and grazing sheep and cattle on grasses high in water soluble carbohydrate result in less nitrogen excretion in urine and reduced ammonia volatilization.

关键词： options for reducing the negative effects, nitrogen in agriculture.

Sleep as a window to understand and regulate Alzheimer's disease:emerging roles of thalamic reticular nucleus

在线全文

学校读者我要写书评

暂无评论

Neural regeneration research 2025年第6期20卷 1711-1712页

作者： Haoqi Sun Shiqian Shen robert j.Thomas M.Brandon Westover Can Zhang Department of Neurology Beth Israel Deaconess Medical CenterHarvard Medical SchoolBostonMAUSA Center for Translational Pain research Department of AnesthesiaCritical Care and Pain MedicineMassachusetis General HospitalHarvard Medical SchoolBostonMAUSA Division of Pulmonary Critical Care and Sleep MedicineDepartment of MedicineBeth Israel Deaconess Medical CenterHarvard Medical SchoolBostonMAUSA Genetics and Aging research Unit McCance Center for Brain HealthMass General Institute for Neurodegenerative DiseaseDepartment of NeurologyMassachusetts General HospitalHarvard Medical SchoolBostonMAUSA

Introduction:Alzheimer 's disease(AD) is a common neurodegenerative disorder and the primary cause of dementia. Considerable evidence supports the “amyloid hypothesis,” stating that the pathogenesis of AD is primarily caused by the deposition of amyloid-β(Aβ), which drives tau phosphorylation, neuroinflammation, and neurodegeneration in the brain. The amyloid hypothesis is strengthened by the significant and moderate benefit of lecanemab, a humanized antibody through an anti-amyloid mechanism,showing slowed clinical decline(van Dyck et al.,2023). The recent positive results of anti-amyloid trials have brought back focus on the amyloid hypothesis through biochemical, genetic, and pharmacological approaches(Zhang, 2023).

关键词： Alzheimer inflammation hypothesis

NECAB family of neuronal calcium-binding proteins in health and disease

在线全文

学校读者我要写书评

暂无评论

Neural regeneration research 2025年第5期20卷 1236-1243页

作者： Diones Bueno Michael K.E.Schafer Sudena Wang Michael j.Schmeisser Axel Methner Institute for Molecular Medicine University Medical Center of the Johannes Gutenberg-UniversityMainzGermany Department of Anesthesiology University Medical Center of the Johannes Gutenberg-UniversityMainzGermany Institute of Anatomy University Medical Center of the Johannes Gutenberg-UniversityMainzGermany

The N-terminal EF-hand calcium-binding proteins 1–3(NECAB1–3) constitute a family of predominantly neuronal proteins characterized by the presence of at least one EF-hand calcium-binding domain and a functionally less well characterized C-terminal antibiotic biosynthesis monooxygenase domain. All three family members were initially discovered due to their interactions with other proteins. NECAB1 associates with synaptotagmin-1, a critical neuronal protein involved in membrane trafficking and synaptic vesicle exocytosis. NECAB2 interacts with predominantly striatal G-protein-coupled receptors, while NECAB3 partners with amyloid-β A4 precursor protein-binding family A members 2 and 3, key regulators of amyloid-β production. This demonstrates the capacity of the family for interactions with various classes of proteins. NECAB proteins exhibit distinct subcellular localizations: NECAB1 is found in the nucleus and cytosol, NECAB2 resides in endosomes and the plasma membrane, and NECAB3 is present in the endoplasmic reticulum and Golgi apparatus. The antibiotic biosynthesis monooxygenase domain, an evolutionarily ancient component, is akin to atypical heme oxygenases in prokaryotes but is not wellcharacterized in vertebrates. Prokaryotic antibiotic biosynthesis monooxygenase domains typically form dimers, suggesting that calcium-mediated conformational changes in NECAB proteins may induce antibiotic biosynthesis monooxygenase domain dimerization, potentially activating some enzymatic properties. However, the substrate for this enzymatic activity remains uncertain. Alternatively, calcium-mediated conformational changes might influence protein interactions or the subcellular localization of NECAB proteins by controlling the availability of protein–protein interaction domains situated between the EF hands and the antibiotic biosynthesis monooxygenase domain. This review summarizes what is known about genomic organization, tissue expression, intracellular localization, interac

关键词： calcium EF hand mitochondria nervous system signal transduction

Optimal treatment of stratified Carreau and Casson nanofluids flows in Darcy-Forchheimer porous space over porous matrix

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2020年第11期41卷 1651-1670页

作者： r.KUMAr r.KUMAr S.A.SHEHZAD A.j.CHAMKHA Department of Mathematics Central University of Himachal PradeshDharamshala 273001India Department of Mathematics COMSATS University IslamabadSahiwal 57000Pakistan Institute of research and Development Duy Tan UniversityDa Nang 550000Vietnam Institute of Theoretical and Applied research(ITAr) Duy Tan UniversityHanoi 100000Vietnam

A comparative three-dimensional(3D)analysis for Casson-nanofluid and Carreau-nanofluid flows due to a flat body in a magnetohydrodynamic(MHD)stratified environment is *** is estimated to be suspended in a Darcy-Forchheimer *** and Dufour responses are also accommodated in the flow field.A moving(rotating)coordinate system is exercised to examine the bidirectionally stretched flow fields(flow,heat transfer,and mass transfer).Nanofluid is compounded by taking ethylene glycol/sodium alginate as base fluid and ferric-oxide(Fe3O4)as *** equations are handled by the application of optimal homotopy asymptotic method(OHAM),where convergence parameters are optimized through the classical least square *** novel mechanism(hidden physics)due to appearing parameters is explored with the assistance of tabular and graphical *** reveal the double behavior state for temperature field with thermal stratification/Dufour number,and for concentration field with Soret number due to the presence of turning points.

关键词： thermal-solutal stratification Soret-Dufour effect Casson-Carreau nanofluid model porous matrix

Differences in sensitivity of native and exotic fish species to changes in river temperature

在线全文

学校读者我要写书评

暂无评论

Current Zoology 2011年第6期57卷 852-862页

作者： r.S.E.W. LEUVEN A.j. HENDrIKS M.A.j. HUIjBrEGTS H.j.r. LENDErS j. MATTHEWS VAN DEr VELDE radboud University Nijmegen Institute for Water and Wetland Research Department of Environmental Science Heyendaal- seweg 135 NL-6525 AJ Nijmegen The Netherlands radboud University Nijmegen Institute for Water and Wetland Research Department of Animal Ecology and Ecophysiology Heyendaalseweg 135 NL-6525 AJ Nijmegen The Netherlands Netherlands Centre for Biodiversity Naturalis P.O. Box 9517 NL-2300 RA Leiden The Netherlands

This paper describes the effects that temperature changes in the rhine river distributaries have on native and exotic fish diversity. Site-specific potentially affected fractions （PAFs） of the regional fish species pool were derived using species sensitivity distributions （SSDs） for water temperature. The number of fish species in the river distributaries has changed remarkably over the last century. The number of native rheophilous species declined up until 1980 due to anthropogenic disturbances such as commercial fishing, fiver regulation, migration barriers, habitat deterioration and water pollution. In spite of progress in river re- habilitation, the native rheophilous fish fauna has only partially recovered thus far. The total number of species has strongly in- creased due to the appearance of more exotic species. After the opening of the rhine-Main-Danube waterway in 1992, many fish species originating from the Ponto-Caspian area colonized the rhine basin. The yearly minimum and maximum river tempera- tures at Lobith have increased by circa 4 ~C over the period 1908-2010. Exotic species show lower PAFs than native species at both ends of the temperature range. The interspecific variation in the temperature tolerance of exotic fish species was found to be large. Using temporal trends in river temperature allowed past predictions of PAFs to demonstrate that the increase in maximum river temperature negatively affected a higher percentage of native fish species than exotic species. Our results support the hy- pothesis that alterations of the river rhine＇s temperature regime caused by thermal pollution and global wanning limit the full recovery of native fish fauna and facilitate the establishment of exotic species which thereby increases competition between native and exotic species. Thermal refuges are important for the survival of native fish species under extreme summer or winter temperature conditions

关键词： Aquatic invaders Global warming Heat discharges Lethal temperature river rhine Thermal heterogeneity

Apoptosis and DNA damage in human spermatozoa

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

Asian journal of Andrology 2011年第1期13卷 36-42页

作者： r john Aitken Adam j Koppers ArC Centre of Excellence in Biotechnology and Development Priority Research Centre in Reproductive Science Discipline of Biological Sciences School of Environmental and Life Sciences University of Newcastle Callaghan NSW 2308 Australia Department of Anatomy and Developmental Biology School of Biomedical Sciences Monash University Clayton VIC 3800 Australia

DNA damage is frequently encountered in spermatozoa of subfertile males and is correlated with a range of adverse clinical outcomes including impaired fertilization, disrupted preimplantation embryonic development, increased rates of miscarriage and an enhanced risk of disease in the progeny. The etiology of DNA fragmentation in human spermatozoa is closely correlated with the appearance of oxidative base adducts and evidence of impaired spermiogenesis. We hypothesize that oxidative stress impedes spermiogenesis, resulting in the generation of spermatozoa with poorly remodelled chromatin. These defective cells have a tendency to default to an apeptotic pathway associated with motility loss, caspase activation, phosphatidylserine exteriorization and the activation of free radical generation by the mitochondria. The latter induces lipid peroxidation and oxidative DNA damage, which then leads to DNA fragmentation and cell death. The physical architecture of spermatozoa prevents any nucleases activated as a result of this apoptotic process from gaining access to the nuclear DNA and inducing its fragmentation. It is for this reason that a majority of the DNA damage encountered in human spermatozoa seems to be oxidative. Given the important role that oxidative stress seems to have in the etiology of DNA damage, there should be an important role for antioxidants in the treatment of this condition. If oxidative DNA damage in spermatozoa is providing a sensitive readout of systemic oxidative stress, the implications of these findings could stretch beyond our immediate goal of trying to minimize DNA damage in spermatozoa as a prelude to assisted conception therapy.

关键词： apoptosis DNA damage oxidative stress spermatozoa

Dependency-aware unequal erasure protection codes

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

journal of Zhejiang University-Science A(Applied Physics & Engineering) 2006年第z1期7卷 27-33页

作者： BOUABDALLAH Amine LACAN jérme Laboratory for Analysis and Architecture of Systems Toulouse 31077 France Applied Mathematics and Computer Science DepartmentENSICAToulouse 31056France Telecommunications for Space and AeronauticToulouse 31000France

Classical unequal erasure protection schemes split data to be protected into classes which are encoded independently. The unequal protection scheme presented in this paper is based on an erasure code which encodes all the data together according to the existing dependencies. A simple algorithm generates dynamically the generator matrix of the erasure code according to the packets streams structure, i.e., the dependencies between the packets, and the rate of the code. This proposed erasure code was applied to a packetized MPEG4 stream transmitted over a packet erasure channel and compared with other classical protection schemes in terms of PSNr and MOS. It is shown that the proposed code allows keeping a high video quality-level in a larger packet loss rate range than the other protection schemes.

关键词： Data dependencies integration Unequal erasure protection (UEP) Lossy networks reliable video transmissions MPEG4 video codec

OSCILLATION AND VArIATION OF THE LAGUErrE HEAT AND POISSON SEMIGrOUPS AND rIESZ TrANSFOrMS

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Scientia 2012年第3期32卷 907-928页

作者： j.j.Betancor r.Crescimbeni j.L.Torrea Departamento de An'aisis Matema'ico Universidad de La Laguna38271-La LagunaTenerifeIslas CanariasSpain Departamento de Matema'ica Universidad Nacional del ComahueBuenos Aires 14008300 Neuqu'enArgentina Departamento de Matem'aticas Facultad de CienciasUniversidad Auto'noma de Madrid28049 MadridSpain

In this article, we study LP-boundedness properties of the oscillation and vari- ation operators for the heat and Poissson semigroup and riesz transforms in the Laguerre settings. Also, we characterize Hardy spaces as... 详细信息

关键词： Oscillation variation heat Laguerre semigroup riesz transforms