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Elements of disturbance that affect epiphyte vitality in a temperate rainforest:an experimental approach

Journal of Plant Ecology 2019年第2期12卷 306-313页

作者： Nalini M.Nadkarni kevin d.kohl department of Biology University of Utah257 South 1400 EastSalt Lake CityUT 84112USA department of Biological Sciences University of Pittsburgh403B Clapp Hall4249 Fifth AvenuePittsburghPA 115260USA

Aims Epiphytes are an abundant and diverse component of many wet temperate forests and have significant roles in ecosystem *** is known about the processes and rates of their death and decomposition when they fall from the canopy,which limits our understanding of their role in forest carbon sequestration and nutri-ent *** the temperate rainforest of the Quinault River Valley,Washington State,our aim was to test hypotheses regarding four elements of disturbance that might contribute to their *** We established set of experiments in which we placed samples of canopy epiphytes and their branch segments:(i)in the canopy versus forest floor microenvironment(stratum);(ii)attached to live versus dead branch substrates;(iii)subjected to physical disruption and‘jarring’;and(iv)in direct versus indirect con-tact with the forest *** the 2-year study,we assigned a non-destructive‘vitality index’(based on color and appar-ent mortality and dryness)to each sample every 2-3 months to compare effects of the experimental treatments and analyzed with a statistical model and post hoc pairwise comparisons of *** Findings The canopy versus ground stratum and live/dead branch status sig-nificantly affected epiphyte *** of physical disruption and ground contact were not *** were seasonal effects(low vitality during the sampling times in the summer,revitalization upon sampling times in the winter)for all treatments except samples in contact with the *** implication of these results relates to effects of climate change,which is predicted to shift to hotter,drier summers and wetter *** change may affect forest dynamics and nutrient cycling in unpredictable *** also point to future experiments to understand biotic and abiotic effects on epiphyte disturbance and dynamics.

关键词： disturbance epiphytes forest canopy forest dynamics moss Olympic rainforest

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Gut microbes limit growth in house sparrow nestlings(Passer domesticus)but not through limitations in digestive capacity

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Integrative Zoology 2018年第2期13卷 139-151页

作者： kevin d.kohl Antonio BRUN Seth R.BORdENSTEIN Enrique CAVIEdES-VIdAL William H.KARASOV department of Biological Sciences Vanderbilt UniversityNashvilleTennesseeUSA department of Biological Sciences University of PittsburghPittsburghPennsylvaniaUSA department of Forest and Wildlife Ecology University of Wisconsin-MadisonMadisonWisconsinUSA department of Pathology Microbiologyand ImmunologyVanderbilt UniversityNashvilleTennesseeUSA Institute for Multidisciplinary Research in Biology of San Luis National Scientific and Technical Research CouncilSan LuisArgentina department of Biochemistry and Biological Sciences Universidad Nacional de San LuisSan LuisArgentina

Recent research often lauds the services and beneficial effects of host-associated microbes on ***,hosting these microbes may come at a *** example,germ-free and antibiotic-treated birds generally grow faster than their conventional *** the wild,juvenile body size is correlated with survival,so hosting a microbiota may incur a fitness *** altricial nestlings represent an interesting study system in which to investigate these interactions,given that they exhibit the fastest growth rates among vertebrates,and growth is limited by their digestive *** investigated whether reduction and restructuring of the microbiota by antibiotic treatment would:(i)increase growth and food conversion efficiency in nestling house sparrows(Passer domesticus);(ii)alter aspects of gut anatomy or function(particularly activities of digestive carbohydrases and their regulation in response to dietary change);and(iii)whether there were correlations between relative abundances of microbial taxa,digestive function and nestling *** treatment significantly increased growth and food conversion efficiency in *** did not alter aspects of gut anatomy that we considered but depressed intestinal maltase *** were no significant correlations between abundances of microbial taxa and aspects of host ***,we conclude that microbial-induced growth limitation in developing birds is not driven by interactions with digestive ***,decreased energetic and material costs of immune function or beneficial effects from microbes enriched under antibiotic treatment may underlie these *** the costs and tradeoffs of hosting gut microbial communities represents an avenue of future research.

关键词： antibiotics food conversion efficiency gut microbiota host-microbe interactions maltase

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Real-world emission factors for Caterpillar 797B heavy haulers during mining operations

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Particuology 2016年第5期14卷 22-30页

作者： Xiaoliang Wang Judith C. Chow Steven d. kohl kevin E. Percy Allan H. Legge John G. Watson desert Research Institute 2215 Raggio Parkway Reno NV 895J2 USA Graduate Faculty University of Nevada Reno NV89503 USA The State Key Laboratory of Loess and Quaternary Geology Institute of Earth Environment Chinese Academy of Sciences Xi'an 710075 China Wood Buffalo Environmental Association 330 Thickwood Boulevard Fort McMurray AB Canada 7DK 1 Y1 Biosphere Solutions 1610 1 lth Avenue N.W. Calgary AB Canada T2N IG9

Real-world fuel-based emission factors （EFs） from Caterpillar 797B diesel heavy haulers when used for oil sands mining operations were measured using an on-hoard portable emissions monitoring system. Average EFs （in g/kg fuel） for 16 separate tests on four trucks were 3150 ± 4 for CO2, 2.51 ± 1.30 for CH4, 10.28 ± 3.21 for CO, 0.61 ± 0.32 for non-methane hydrocarbons, 55.49 ± 9,75 for NOx （reported as NO2）, 0.70 ± 0.17 for PM2.s （mass of particles with aerodynamic diameter 〈2.5 μm）, and 0.34 ± 0.05 for black carbon （BC）. Ultrafine particle numbers averaged （4.7 ± 4.1 ） × 10^15 particleslkg fuel. Fuel-based EFs of NO, NO2, and particle numbers were higher during idling, whereas PM2.5 and BC EFs were higher during traveling without a load. A comparison of emissions with those reported by oil sands facilities showed large variations, both among the facilities and between the reported emissions and the real-world measurements.

关键词： Heavy hauler Emission Nonroad Portable emissions measurement system Mining Oil sands

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JUMPING INSTABILITIES IN THE POST-BUCKLING OF A BEAM ON A PARTIAL NONLINEAR FOUNdATION

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Acta Mechanica Solida Sinica 2013年第5期26卷 500-513页

作者： Yin Zhang kevin d Murphy State Key Laboratory of Nonlinear Mechanics (LNM) Institute of Mechanics Chinese Academy of Sciences department of Mechanical Engineering University of Connecticut

Mode jumping is an instability phenomenon in the post-buckling region, which causes a sudden change in the equilibrium configuration and is thus harmful to structure. The con- figuration of a partial elastic foundation can directly induce mode coupling from the buckling stage and through the whole post-buckling region. The mode coupling effect due to the configuration of partial foundation on mode jumping is investigated and demonstrated to be an important factor of determining mode jumping. By properly choosing the partial elastic foundation configuration, mode jumping can be avoided.

关键词： instability mode jumping tertiary jumping buckling beam elastic foundation

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Tensionless contact of a finite circular plate

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Acta Mechanica Sinica 2012年第5期28卷 1374-1381页

作者： Yin Zhang kevin d.Murphy State Key Laboratory of Nonlinear Mechanics(LNM) Institute of MechanicsChinese Academy of Sciences department of Mechanical Engineering the University of Connecticut

A general formulation is developed for the contact behavior of a finite circular plate with a tensionless elastic foundation. The gap distance between the plate and elastic foundation is incorporated as an important parameter. Unlike the previous models with zero gap distance and large/infinite plate radius, which assumes the lift-off/separation of a flexural plate from its supporting elastic foundation, this study shows that lift-off may not occur. The results show how the contact area varies with the plate radius, boundary conditions and gap distance. When the plate radius becomes large enough and the gap distance is reduced to zero, the converged contact radius close to the previous ones is obtained.

关键词： Tensionless contact Elastic foundation Plate Lift-off

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Tensionless contact of a finite beam:Concentrated load inside and outside the contact zone

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Acta Mechanica Sinica 2013年第6期29卷 836-839页

作者： Yin Zhang kevin d.Murphy State Key Laboratory of Nonlinear Mechanics Institute of MechanicsChinese Academy of Sciences department of Mechanical Engineering University of ConnecticutStorrsCT 06268USA

For a finite beam with a nonzero gap distance, an asymmetric concentrated load can be either inside or outside of the contact zone. A new governing equation is given for the case of a concentrated load outside the contact zone. By numerically solving the left-side and right-side contact lengths of the beam, a criterion is established to determine whether the concentrated load is inside or outside the contact zone. A more general approach on the tensionless contact of a beam is thus presented.

关键词： Tensionless contact Lift-off Beam

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Testosterone and cardiovascular disease in men

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Asian Journal of Andrology 2012年第3期14卷 428-435,I0007页

作者： Paul d Morris kevin S Channer Sheffield Teaching Hospital NHS Trust Sheffield S10 2JF UK

despite regional variations in the prevalence of coronary artery disease （CAd）, men are consistently more at risk of developing and dying from CAd than women, and the gender-specific effects of sex hormones are implicated in this inequality. This ＇Perspectives＇ article reviews the current evidence regarding the cardiovascular effects of testosterone in men including an examination of the age-related decline in testosterone, the relationship between testosterone levels and coronary disease, coronary risk factors and mortality. We also review the vaso-active effects of testosterone, and discuss how these have been used in men with heart failure and angina. We discuss the ＇cause＇ versus ＇effect＇ controversy, regarding low testosterone levels in men with coronary heart disease, as well as concerns over the use of testosterone replacement therapy in middle aged and elderly men. The article concludes with a discussion regarding the future direction for work in this interesting area, including the relative merits of screening for, and treating hypogonadism with testosterone replacement therapy in men with heart disease.

关键词： atherosclerosis chronic heart failure ischaemic heart disease replacement therapy testosterone

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CRACK PROPAGATION IN STRUCTURES SUBJECTEd TO PERIOdIC EXCITATION

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Acta Mechanica Solida Sinica 2007年第3期20卷 236-246页

作者： Zhang Yin Murphy kevin d. State Key Laboratory of Nonlinear Mechanics （LNM） Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China department of Mechanical Engineering University of Connecticut CT 06269-3139 USA

In the present paper, asimple mechanical modelis developed to predict thedynamic response of a cracked structure subjected to periodic excitation, which has been used to identify the physical mechanisms in leading the growth or arrest of cracking. The structure under consideration consists of a beam with a crack along the axis, and thus, the crack may open in Mode I and in the axial direction propagate when the beam vibrates. In this paper, the system is modeled as a cantilever beam lying on a partial elastic foundation, where the portion of the beam on the foundation represents the intact portion of the beam. Modal analysis is employed to obtain a closed form solution for the structural response. Crack propagation is studied by allowing the elastic foundation to shorten （mimicking crack growth） if a displacement criterion, based on the material toughness, is met. As the crack propagates, the structural model is updated using the new foundation length and the response continues. From this work, two mechanisms for crack arrest are identified. It is also shown that the crack propagation is strongly influenced by the transient response of the structure.

关键词： crack propagation/arrest elastic foundation modal analysis vibration natural frequency

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Nonlinear dynamic response of beam and its application in nanomechanical resonator

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Acta Mechanica Sinica 2012年第1期28卷 190-200页

作者： Yin Zhang Yun Liu kevin d.Murphy State Key Laboratory of Nonlinear Mechanics Institute of MechanicsChinese Academy of Sciences100190 BeijingChina Faculty of Information and Automation Kunming University of Science and Technology650051 KunmingChina department of Mechanical Engineering The University of ConnecticutStorrsCT 06269USA

Nonlinear dynamic response of nanomechanical resonator is of very important characteristics in its application. Two categories of the tension-dominant and curvaturedominant nonlinearities are analyzed. The dynamic nonlinearity of four beam structures of nanomechanical resonator is quantitatively studied via a dimensional analysis approach. The dimensional analysis shows that for the nanomechanical resonator of tension-dominant nonlinearity, its dynamic nonlinearity decreases monotonically with increasing axial loading and increases monotonically with the increasing aspect ratio of length to thickness; the dynamic nonlinearity can only result in the hardening effects. However, for the nanomechanical resonator of the curvature-dominant nonlinearity, its dynamic nonlinearity is only dependent on axial loading. Compared with the tension-dominant nonlinearity, the curvature-dominant nonlinearity increases monotonically with increasing axial loading; its dynamic nonlinearity

关键词： Resonator. dynamic response. dynamic nonlinearity - dimensional analysis

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Epitypification:should we epitypify?

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2008年第10期9卷 842-846页

作者： kevin d. HYdE Ying ZHANG International Fungal Research and development Centre the Research Institute of Resource Insects Chinese Academy of Forestry Kunming 650224 China Fungal Research Group School of Science Mae Fah Luang University Tasud Muang Chiang Rai 5 7100 Thailand Centre for Research in Fungal diversity School of Biological Sciences University of Hong Kong Hong Kong China

Epitypification can solve many taxonomic problems and stabilize the understanding of species, genera, families or orders. The aim of this paper is to illustrate how to epitypify. A few examples where taxa have been epitypified are considered and the benefits and disadvantages of epitypification are discussed. We also outline some examples of taxa which need to be epitypifled with reasons.

关键词： Colletotrichum GenBank Molecular phylogeny Taxonomy Typification

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