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Deterministic processes drive turnover-dominated beta diversity of breeding birds along the central Himalayan elevation gradient

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Avian Research 2024年第2期15卷 163-171页

作者： Zhifeng Ding Jianchao Liang Le Yang Cong Wei Huijian Hu Xingfeng Si Guangdong Key Laboratory of Animal Conservation and Resource Utilization Institute of ZoologyGuangdong Academy of SciencesGuangzhouGuangdong510260China Tibet Plateau Institute of Biology Lhasa850001China Zhejiang Zhoushan Island Ecosystem Observation and Research Station Institute of Eco-ChongmingZhejiang Tiantong Forest Ecosystem National Observation and Research StationSchool of Ecological and Environmental SciencesEast China Normal UniversityShanghai200241China

Beta diversity,the variation of community composition among sites,bridges alpha and gamma diversity and can reveal the mechanisms of community assembly through applying distance-decay models and/or partitioning beta diversity into turnover and nestedness components from functional and phylogenetic perspectives.Mountains as the most natural experiment system provide good opportunities for exploring beta diversity patterns and the underlying ecological processes.Here,we simultaneously consider distance-decay models and multiple di-mensions of beta diversity to examine spatial variations of bird communities,and to evaluate the relative importance of niche-based and neutral community assembly mechanisms along a 3600-m elevational gradient in the central Himalayas,China.Our results showed that species turnover dominates taxonomic,functional,and phylogenetic beta diversity.We observed strongest evidence of spatial distance decays in taxonomic similarities of birds,followed by its phylogenetic and functional analogues.turnover component was highest in taxonomic beta diversity,while nestedness component was highest in functional beta diversity.Further,all correlations of assemblage similarity with climatic distance were higher than that with spatial distances.Standardized values of overall taxonomic,functional,and phylogenetic beta diversity and their turnover components increase with increasing elevational distance,while the standardized values of taxonomic and phylogenetic nestedness decreased with increasing elevational distance.Our results highlighted the niche-based deterministic processes in shaping elevational bird diversity patterns that were determined by the relative roles of decreasing trend of environmental filtering and increasing trend of limiting similarity along elevation distances.

关键词： Beta diversity Bird Community assembly Functional trait Himalaya Nestedenss Phylogenetic distance turnover

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Applying zeta diversity to understand species turnover patterns of small mammals in the Mountains of Southwest China

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动物学研究(英文) 2023年第5期44卷 939-942页

作者： Jin-Zhao Ke Zhi-Xin Wen Ming-Qiang Wang Anderson Feijó Tian Tian Lin Xia Qi-Sen Yang Key Laboratory of Zoological Systematics and Evolution Institute of ZoologyChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 10049China CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization&Biodiversity Conservation Key Laboratory of Sichuan Province Chengdu Institute of BiologyChinese Academy of SciencesChengduSichuan 610041China

DEAR EDITOR,Mountainous regions are generally characterized by high species turnover,yet studies applying novel conceptual frameworks to analyze the spatial structure and organization of montane biota along elevational gradients remain scarce.Based on the zeta diversity framework—a novel turnover metric that focuses on average number of species shared across sites—and a comprehensive presence-absence dataset of small mammals collected from 22 elevational gradients in the Mountains of Southwest China(MSC).

关键词： mammals Mountains turnover

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Arabidopsis AIP1-1 regulates the organization of apical actin filaments by promoting their turnover in pollen tubes

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Science China(Life Sciences) 2020年第2期63卷 239-250页

作者： Min Diao Xin Li Shanjin Huang Institute of Botany Chinese Academy of SciencesBeijing 100093China Center for Plant Biology School of Life SciencesTsinghua UniversityBeijing 100084China University of Chinese Academy of Sciences Beijing 100049China iHuman Institute Shanghai Tech UniversityShanghai 201210China

Apical actin filaments are highly dynamic structures that are crucial for rapid pollen tube growth, but the mechanisms regulating their dynamics and spatial organization remain incompletely understood. We here identify that AtAIP1-1 is important for regulating the turnover and organization of apical actin filaments in pollen tubes. AtAIP1-1 is distributed uniformly in the pollen tube and loss of function of AtAIP1-1 affects the organization of the actin cytoskeleton in the pollen tube. Specifically, actin filaments became disorganized within the apical region of aip1-1 pollen tubes. Consistent with the role of apical actin filaments in spatially restricting vesicles in pollen tubes, the apical region occupied by vesicles becomes enlarged in aip1-1 pollen tubes compared to WT. Using ADF1 as a representative actin-depolymerizing factor, we demonstrate that AtAIP1-1 enhances ADF1-mediated actin depolymerization and filament severing in vitro, although AtAIP1-1 alone does not have an obvious effect on actin assembly and disassembly. The dynamics of apical actin filaments are reduced in aip1-1 pollen tubes compared to WT. Our study suggests that AtAIP1-1 works together with ADF to act as a module in regulating the dynamics of apical actin filaments to facilitate the construction of the unique "apical actin structure" in the pollen tube.

关键词： pollen tube apical actin structure actin dynamics actin turnover ADF AIP1

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Turning to myelin turnover

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Neural Regeneration Research 2019年第12期14卷 2063-2066页

作者： Tobias J.Buscham Maria A.Eichel Sophie B.Siems Hauke B.Werner Department of Neurogenetics Max Planck Institute of Experimental Medicine

Neural plasticity in the adult central nervous system involves the adaptation of myelination, including the formation of novel myelin sheaths by adult-born oligodendrocytes. Yet, mature oligodendrocytes slowly but constantly turn over their pre-existing myelin sheaths, thereby establishing an equilibrium of replenishment and degradation that may also be subject to adaptation with consequences for nerve conduction velocity. In this short review we highlight selected approaches to the normal turnover of adult myelin in vivo, from injecting radioactive precursors of myelin constituents in the 1960s to current strategies involving isotope labeling and tamoxifen-induced gene targeting.

关键词： oligodendrocyte myelin plasticity and turnover degradation tamoxifen metabolic labeling isotope labeling neural plasticity myelinoid bodies central nervous system

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Contribution of high risk groups’unmet needs may be underestimated in epidemic models without risk turnover:A mechanistic modelling analysis

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Infectious Disease Modelling 2020年第1期5卷 549-562页

作者： Jesse Knight Stefan D.Baral Sheree Schwartz Linwei Wang Huiting Ma Katherine Young Harry Hausler Sharmistha Mishra MAP Centre for Urban Health Solutions Unity Health TorontoCanada Deptartment of Epidemiology Johns Hopkins Bloomberg School of Public HealthUSA TB HIV Care South Africa Division of Infectious Disease Department of MedicineUniversity of TorontoCanada Institute of Health Policy Management and EvaluationDalla Lana School of Public HealthUniversity of TorontoCanada Institute of Medical Sciences University of TorontoCanada

Background:Epidemic models of sexually transmitted infections(STIs)are often used to characterize the contribution of risk groups to overall transmission by projecting the transmission population attributable fraction(tPAF)of unmet prevention and treatment needs within risk groups.However,evidence suggests that STI risk is dynamic over an individual’s sexual life course,which manifests as turnover between risk groups.We sought to examine the mechanisms by which turnover influences modelled projections of the tPAF of high risk groups.Methods:We developed a unifying,data-guided framework to simulate risk group turnover in deterministic,compartmental transmission models.We applied the framework to an illustrative model of an STI and examined the mechanisms by which risk group turnover influenced equilibrium prevalence across risk groups.We then fit a model with and without turnover to the same risk-stratified STI prevalence targets and compared the inferred level of risk heterogeneity and tPAF of the highest risk group projected by the two models.Results:The influence of turnover on group-specific prevalence was mediated by three main phenomena:movement of previously high risk individuals with the infection into lower risk groups;changes to herd effect in the highest risk group;and changes in the number of partnerships where transmission can occur.Faster turnover led to a smaller ratio of STI prevalence between the highest and lowest risk groups.Compared to the fitted model without turnover,the fitted model with turnover inferred greater risk heterogeneity and consistently projected a larger tPAF of the highest risk group over time.Implications:If turnover is not captured in epidemic models,the projected contribution of high risk groups,and thus,the potential impact of prioritizing interventions to address their needs,could be underestimated.To aid the next generation of tPAF models,data collection efforts to parameterize risk group turnover should be prioritized.

关键词： Mathematical modelling Transmission Risk heterogeneity turnover Sexually transmitted infection Population attributable fraction

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Reducing turnover intention: Perceived organizational support for frontline employees

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Frontiers of Business Research in China 2020年第1期14卷 104-119页

作者： Qiang Wang Chao Wang Business School Renmin University of ChinaBeijing 100872China

Frontline employees are generally under great pressure,and carry out repetitive and mundane daily tasks,leading to burnout and a high turnover intention among them.To identify ways to reduce this turnover intention,this study examines the effect of perceived organizational support(POS)on burnout and turnover intention in the Chinese context and adds to the literature on frontline employee burnout.Using data from a survey of the frontline employees of a gas station in Beijing,we examine the mediating effects of frontline employee burnout on their POS and turnover intention.This study shows that POS has a significant negative impact on burnout and turnover intention,and that job resources cannot substitute POS.

关键词： Perceived organizational support(POS) Burnout Retail frontline employees Job resources Job demands turnover intention

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Job burnout and turnover intention among nurses in China:the mediating effects of positive emotion

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Frontiers of Nursing 2018年第1期5卷 43-47页

作者： Li-Feng Yang Jing-Ying Liu Yan-Hui Liu School of Nursing Tianjin University of Traditional Chinese MedicineTianjin 300193China

Objective: The aim of this study was to explore whether positive emotion mediates the relationship between job burnout and turnover intentions among Chinese nurses.Methods: A cross-sectional survey was conducted in the present study. Full-time registered nurses(n = 150) from Grade A hospitals in Tianjin were surveyed. Pearson correlation, hierarchical regression analyses, and the Sobel test were used in the study.Results: The results illustrated that positive emotion mediated the relationship between burnout and nurses' turnover intention.Conclusions: Nursing administrators should pay more attention to the benefits of positive emotions on working motivation.It is helpful to relieve burnout in the working process so that nurses are willing to remain in their current employment.

关键词： positive emotion burnout turnover intentions

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Influence of local and landscape environmental factors on alpha and beta diversity of macroinvertebrates in Andean rivers

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Journal of Mountain Science 2023年第9期20卷 2487-2501页

作者： DIAZ-ROJAS Camila A PEDROZA-RAMOS Adriana X BARRERA-HERRERA July A ROA-FUENTES Camilo A Ecology Unit in Aquatic Systems Research Group Pedagogical and Technological University of ColombiaUPTCAvenida Central del Norte 39-115TunjaBoyacáColombia

Research on macroinvertebrate community structure in Andean rivers has been oriented towards describing patterns of alpha and gamma diversity by taking into account environmental predictors at local spatial scales(e.g.,micro-and mesohabitats).However,the patterns of beta diversity and the importance of landscape-scale variables have been evaluated to a lesser extent.The objective of this study was to describe the patterns of alpha and beta diversity of benthic macroinvertebrates in the Andean rivers of the Orinoco basin and their relationship with local and landscape environmental variation.A stratified random sampling of macroinvertebrates was carried out at 40 sites(comprising an altitudinal range of between 500 and 2900 m.a.s.l.),local and landscape variables were measured.Our results showed that the variation of alpha diversity was influenced by local and landscape variables,which are directly and indirectly related to the contribution of sediments,substrate composition and flow velocity,providing a heterogeneity of habitats.Global beta diversity was explained by the combined effect of local and landscape variables.Regarding the beta diversity phenomena,turnover was predominant while nestedness presented a minor contribution and both were explained in greater proportion by local descriptors and some landscape variables,specifically those of a geomorphological nature.Our results concur with the view of an environmental and spatial hierarchy within the river habitat and highlight the influence of multiple scales on macroinvertebrate diversity.The above suggests that both local and landscape scales must necessarily be considered for environmental management and the conservation of Andean lotic ecosystems.

关键词： Andean lotic systems Andean agroecosystems Instream habitat Landcover turnover Nestedness

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On the potential of documenting decadal-scale avifaunal change from before-and-after comparisons of museum and observational data across North America

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Avian Research 2022年第1期13卷 1-10页

作者： Fernando Machado-Stredel Benedictus Freeman Daniel Jiménez-Garcia Marlon E.Cobos Claudia Nunez-Penichet Laura Jiménez Ed Komp Utku Perktas Ali Khalighifar Kate Ingenloff Walter Tapondjou Thilina de Silva Sumudu Fernando Luis Osorio-Olvera A.Townsend Peterson Biodiversity Institute and Department of Ecology and Evolutionary Biology University of KansasLawrenceKSUSA Centro de Agroecología y Ambiente Instituto de CienciasBenemérita Universidad Autónoma de PueblaPueblaPueblaMexico Information and Telecommunication Technology Center(ITTC) University of KansasLawrenceKSUSA Department of Biology(Zoology Section-Biogeography Research Lab.) Faculty of ScienceHacettepe UniversityBeytepeAnkaraTurkey Department of Ornithology American Museum of Natural HistoryCentral Park West at 79th StreetNew YorkNYUSA Departamento de Ecología de la Biodiversidad Instituto de EcologíaUniversidad Nacional Autónoma de MéxicoCiudad de MéxicoMéxico

Studies of biodiversity dynamics have been cast on either long(systematics)or short(ecology)time scales,leaving a gap in coverage for moderate time scales of decades to centuries.Large-scale biodiversity information resources now available offer opportunities to fill this gap for many parts of the world via detailed,quantitative comparisons of assemblage composition,particularly for regions without rich time series datasets.We explore the possibility that such changes in avifaunas across the United States and Canada before and after the first three decades of marked global change(i.e.,prior to 1980 versus after 2010)can be reconstructed and characterized from existing primary biodiversity data.As an illustration of the potential of this methodology for sites even in regions not as well sampled as the United States and Canada,we also explored changes at a single site in Mexico(Chichén-Itzá).We analyzed two large-scale datasets:one summarizing bird records in the United States and Canada before 1980,and one for the same region after 2010.We used probabilistic inventory completeness analyses to identify sites that have avifaunas that have likely been inventoried more or less completely.We prepared detailed comparisons between the two time periods to analyze species showing distributional changes over the time period analyzed.We identified 139 sites on a 0.05°grid that were demonstrably well-inventoried before 1980 in the United States and Canada,of which 108 were also well-inventoried after 2010.Comparing presence/absence patterns between the two time periods for 601 bird species,we found significant spatial autocorrelation in overall avifaunal turnover(species gained and lost),but not in numbers of species lost.We noted potential northward retractions of ranges of several species with high-latitude(boreal)distributions,while other species showed dominant patterns of population loss,either rangewide(e.g.,Tympanuchus cupido)or regionally(e.g.,Thryomanes bewickii).We developed linear models to explore a suite of poten

关键词： Biodiversity dynamics Birds Climate change Inventory completeness Time scale turnover

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DETERMINATION OF PROTEIN turnover CHANGES IN PERIOPERATIVE PATIENTS BY THE 15N-GLYCINE CONSTANT INFUSION METHOD

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Chinese Medical Sciences Journal 1990年第2期8卷 97-101页

作者：马恩陵蒋朱明 PUMC Hospital.CAMS Beijing

The N-glycine constant infusion method was used to study protein turnover in normal adultsand perioperative patients.The protein turnover rate （Q）,synthetic rate （S） and catabolicrate （C） were derived according to Picou’s two-pool system model,and the“end-productaveraging technique”showed the 15N-glycine constant iufusion method to be reliable,witha reproducibility of ±5.1%.This measurement can be repeated after a short period,so itshould be useful for surgical nutrition study.Our results show the following:Q was significantly increased after operation （3.4±0.6 to 5.0±0.5 g protein/kg/d,P<0.01）,and S （2.6±0.5 to 3.7±0.6 g protein/kg/d,P<0.05）and C （2.3±0.5 to 3.9±0.5 g protein/kg/d,P<0.01） were increased as well.This suggeststhat the protein degradation rate outstripped the synthesis rate on post-operative day three（POD+3） when traditional （glutamine-free） total parenteral nutrition support was used.

关键词： 15N-glycine constant infusion perioperative protein turnover Chinese perioperative total parenteral nutrition

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