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Analysis of the periodic solutions of a smooth and discontinuous oscillator

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Acta Mechanica Sinica 2013年第4期29卷 575-582页

作者： Zhi-Xin li Qing-Jie Cao Marian Wiercigroch alain léger Centre for Nonlinear Dynamics Research Harbin Institute of Technology School of Astronautics Centre for Applied Dynamics Research School of Engineering University of Aberdeen King's College laboratoire de Mécanique et d' Acoustique CNRS 31 Chemin Joseph Aiguier 13402 Marseille Cedex 20 France

In this paper, the periodic solutions of the smooth and discontinuous （SD） oscillator, which is a strongly irra- tional nonlinear system are discussed for the system having a viscous damping and an external harmonic excitation. A four dimensional averaging method is employed by using the complete Jacobian elliptic integrals directly to obtain the perturbed primary responses which bifurcate from both the hyperbolic saddle and the non-hyperbolic centres of the un- perturbed system. The stability of these periodic solutions is analysed by examining the four dimensional averaged equa- tion using lyapunov method. The results presented herein this paper are valid for both smooth （e 〉 0） and discontin- uous （ce = 0） stages providing the answer to the question why the averaging theorem spectacularly fails for the case of medium strength of external forcing in the Duffing system analysed by Holmes. Numerical calculations show a good agreement with the theoretical predictions and an excellent efficiency of the analysis for this particular system, which also suggests the analysis is applicable to strongly nonlinear systems.

关键词： SD oscillator ~ Averaging method. Periodic so-lution ~ Irrational nonlinearity ~ Elliptic integral

Gust response of an elasto-flexible morphing wing using fluid–structure interaction simulations

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Chinese Journal of Aeronautics 2024年第2期37卷 45-57页

作者： Jonathan PFlÜger Christian BREITSAMTER Department of Mechanical Engineering Technical University of MunichGarching 85748Germany

Small and micro unmanned aircraft are the focus of scientific interest due to their wide range of *** often operate in a highly unstable flight environment where the application of new morphing wing technologies offers the opportunity to improve flight *** investigated concept comprises port and starboard adjustable wings,and an adaptive elastoflexible membrane serves as the lifting *** focus is on the benefits of the deforming membrane during the impact of a one-minus-cosine type *** a low Reynolds number of Re=264000,the morphing wing model is investigated numerically by unsteady fluid-structure interaction ***,the numerical results are validated by experimental data from force and moment,flow field,and deformation ***,with the rigid wing as the baseline,the flexible case is investigated,focusing on the advantages of the elastic *** all configurations studied,the maximum amplitude of the lift coefficient under gust load shows good agreement between the experimental and numerical *** the decay of the gust,they differ more the higher the aspect ratio of the *** considering the flow field,the main differences are due to the separation behavior on the upper side of the *** flow reattaches earlier in the experiments than in the simulations,which explains the higher lift values observed in the *** at one intermediate configuration does the lift amplitude of the rigid configuration exceeds that of the flexible by about 12%,with the elastic membrane resulting in a smaller and more uniform peak load,which is also evident in the wing loading and hence in the root bending moment.

关键词： Membrane wing Morphing wing Flexible wing surface Computational fluid dynam-ics Fluid-structure interaction Unsteady inflow condition Gust response

A Dietary Supplement Jinghuosu Ameliorates Reproductive Damage Induced by Tripterygium Glycosides

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Chinese Journal of Integrative Medicine 2024年第4期30卷 330-338页

作者： MA Jing SUN Bo TE li-ger HUANG Xin ZUO Xin HAN Xiao-ke WANG Shu-song Hebei Key laboratory of Reproductive Medicine Hebei Institute of Reproductive HealthHebei Reproductive Health HospitalShijiazhuang(050071)China Graduate School of Hebei Medical University Shijiazhuang(050017)China School of Chemistry and Materials Science Hebei Normal UniversityShijiazhuang(050024)China Xingtai Infertility Specialist Hospital XingtaiHebei Province(054000)China

Objective To determine the possible protective effects of Jinghuosu,a dietary supplement(DS),on tripterygium glycosides(TG)-induced reproductive system injury in rats and its underlying *** A reproductive damage model was established in rats by feeding of ***-eight male Sprague Dawley rats were randomly divided into 4 groups using a random number table(n=7 in each):control(C)group,model(M)group,DS group and l-carnitine(lC)*** in M,DS and lC groups received 40 mg/kg TGs *** from the 5th week,after administration of TGs for 4 h every day,rats in DS and lC groups were administered with 2.7 g/kg DS and 0.21 g/kg lC,respectively,for protective treatment over the next 4 *** in Group C continued to receive the control ***-eosin staining was used for histopathological analysis of rat testicular ***-linked immunosorbent assay was performed to measure alkaline phosphatase(AlP),lactate dehydrogenase,alcohol dehydrogenase,total antioxidant capacity(T-AOC),superoxide dismutase,glutathione peroxidase(GSH-Px),and malondialdehyde(MDA)*** assay was used to determine the serum testosterone *** real-time PCR and Western blotting were conducted to analyze the expression of genes and proteins related to the testosterone synthesis pathway and the nuclear factor erythroid 2-related factor 2/heme oxygenase 1 antioxidant *** Oral administration of TGs induced significant increases in the testicular levels of zinc transporter 1 and MDA(Plity,and serum testosterone,serum zinc,testicular zinc,Zrt-,Irt-like protein 1,AlP,luteinizing hormone(lH)receptor,steroidogenic acute regulatory protein,Cytochrome P450 family 11 subfamily A member 1,3β-hydroxysteroid dehydrogenase 1 T-AOC,GSH-Px,nuclear factor erythroid 2-related factor 2,heme oxygenase-1 and NAD(P)H:quinone oxidoreductase 1 levels decreased following TG

关键词： dietary supplement Jinghuosu tripterygium glycosides reproductive damage infertility

Differential colour-ring loss among Dalmatian Pelican(Pelecanus crispus) colonies and its consequence on survival estimates

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Avian Research 2024年第1期15卷 66-71页

作者： Anastasios Bounas Giorgos Catsadorakis Dionyssia Hatzilacou Theodoros Naziridis Jocelyn Champagnon alain J.Crivelli Department of Biological Applications and Technology University of IoanninaIoanninaGreece Society for the Protection of Prespa Agios GermanosGreece Natural Environment and Climate Change Agency 207 Mesogeion Ave.11525AthensGreece Natural Environment and Climate Change Agency Kerkini BranchKerkiniGR-62055Kato PoroiaGreece Tour du Valat Research Institute for Conservation of Mediterranean Wetlands13200ArlesFrance

The analysis of bird ringing data often comes with some potential sources of error and bias,as ring wear and/or loss could affect mark-recapture analyses and produce erroneous estimates of ***,ring wear and loss rates may differ between and within species based on the habitat they use or the species’ life-history traits and behaviour as well as the type of the *** this study we use resighting data from a long-term double marking experiment to directly estimate the rate of colour-ring loss among different Dalmatian Pelican colonies over time,evaluate any possible factors that could contribute to differential ring loss and assess how it may bias the results of mark-resighting *** on 14,849 resightings from 1275 individuals and using multi-state continuous-time hidden Markov models(HMMs) we showed that probability of ring loss was markedly different among colonies,ranging from 0.10 to 0.42 within the first year of marking,whereas the cumulative probability of losing a ring after ten years ranged 0.64 to *** rates are among the highest estimated when compared to previous studies in *** approach assessing the intra-specific variance in ring loss provided several factors potentially involved,such as the use of glue and the fledgling age accuracy and we could further hypothesise the effect of environmental ***,our results showed that ring loss can be a significant challenge for the assessment of the species’ population dynamics using mark-recapture methods as survival was consistently underestimated when not accounting for ring loss and varied significantly among different colonies.

关键词： Bias Capture-mark-recapture Colour-ring Double-marking Hidden Markov models

Stepping up after spinal cord injury:negotiating an obstacle during walking

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Neural Regeneration Research 2025年第7期20卷 1919-1929页

作者： alain Frigon Charly G.lecomte Department of Pharmacology-Physiology Faculty of Medicine and Health SciencesUniversitéde SherbrookeCentre de recherche du Centre Hospitalier Universitaire de SherbrookeSherbrookeQCCanada

Every day walking consists of frequent voluntary modifications in the gait pattern to negotiate *** spinal cord injury,stepping over an obstacle becomes *** over an obstacle requires sensorimotor transformations in several structures of the brain,including the parietal cortex,premotor cortex,and motor *** information and planning are transformed into motor commands,which are sent from the motor cortex to spinal neuronal circuits to alter limb trajectory,coordinate the limbs,and maintain *** spinal cord injury,bidirectional communication between the brain and spinal cord is disrupted and animals,including humans,fail to voluntarily modify limb trajectory to step over an ***,in this review,we discuss the neuromechanical control of stepping over an obstacle,why it fails after spinal cord injury,and how it recovers to a certain extent.

关键词： biomechanics locomotion neurophysiology obstacle negotiation spinal cord injury

Mycorrhizal fungi mitigate nitrogen losses of an experimental grassland by facilitating plant uptake and soil microbial immobilization

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Pedosphere 2024年第2期34卷 399-410页

作者： Yangyang JIA Marcel G.A.VAN DER HEIJDEN alain Y.VAlZANO-HElD Markus JOCHER Florian WAlDER Postdoctoral Mobile Station of Ecology College of Ecology and EnvironmentXinjiang UniversityÜrümqi 830046China Research Group Plant-Soil Interactions AgroscopeZürich 8046Switzerland Research Group Climate and Agriculture AgroscopeZürich 8046Switzerland Department of Plant and Microbial Biology University of ZürichZürich 8008Switzerland Research Group Soil Quality and Soil Use AgroscopeZürich 8046Switzerland

Nitrogen(N)is one of the most limited nutrients of terrestrial ecosystems,whose losses are prevented in tightly coupled cycles in finely tuned *** change-induced N enrichment through atmospheric deposition and application of vast amounts of fertilizer are now challenging the terrestrial N *** mycorrhizal fungi(AMF)are known drivers of plant-soil nutrient fluxes,but a comprehensive assessment of AMF involvement in N cycling under global change is still ***,we simulated N enrichment by fertilization(low/high)in experimental grassland microcosms under greenhouse conditions in the presence or absence of AMF and continuously monitored different N pathways over nine *** found that high N enrichment by fertilization decreased the relative abundance of legumes and the plant species dominating the plant community changed from grasses to forbs in the presence of AMF,based on aboveground *** presence of AMF always maintained plant N:phosphorus(P)ratios between 14 and 16,no matter how the soil N availability *** in plant N:P ratios due to the increased plant N and P uptake might thus be a primary pathway of AMF altering plant community ***,we constructed a comprehensive picture of AMF’s role in N cycling,highlighting that AMF reduced N losses primarily by mitigating N leaching,while N_(2)O emissions played a marginal *** mycorrhizal fungi reduced N_(2)O emissions directly through the promotion of N_(2)O-consuming *** underlying mechanism for reducing N leaching is mainly the AMF-mediated improved nutrient uptake and AMF-associated microbial *** results indicate that synergies between AMF and other soil microorganisms cannot be ignored in N cycling and that the integral role of AMF in N cycling terrestrial ecosystems can buffer the upcoming global changes.

关键词： N cycling N enrichment N uptake N:P ratio plant community structure symbiotic soil fungi

Bacterial plant pathogens affect the locomotor behavior of the insect vector:a case study of Citrus volkameriana-Triozae erytreae-Candidatus liberibacter asiaticus system

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Insect Science 2024年第3期31卷 901-910页

作者： Arnaud Ameline alain Karkach Thomas Denoirjean Martial Grondin Florencia Molinari Patrick Turpin Helene Delatte Bernard Reynaud UMR CNRS 7058 EDYSAN(Ecologie et Dynamique des Systemes Anthropises) Universite de Picardie Jules VerneAmiensCedexFrance UMR PVBMT(Peuplements végétaux et bioagresseurs en milieu tropical) Universitéde la RéunionSaint PierreLa RéunionFrance

Plant pathogens can alter the behavior of their insect vectors as well as their survival and *** African psyllid,Trioza erytreae,is one of the vectors of Huanglongbing,a citrus disease caused mainly by"Candidatus liberibacter asiaticus"(Clas).The purpose of this study was to characterize the effects of Clas on the psyllid,*** using Citrus volkamerina plants as the study *** study focused more specifically on the Clas effects prior to and after its acquisition by the psyllid *** results did not support the hypothesis that Clas effects psyllid probing behavior prior to acquisition;few differences were observed between uninfected *** feeding on Clas-infected versus control *** the other hand,compared to psyllids that had completed their development on control plants,the ones that had completed their development on a Clas-infected plant exhibited changes in their behavior(greater velocity),physiology(smaller mass)and biochemistry(lower water and lipid content).Altogether,our results confirm the existence of a marked postacquisition effect on the vector locomotor behavior and a minor preacquisition effect of Clas on the vector behavior,which can be partially explained by physiological and biochemical changes.

关键词： electrical penetration graph Huanglongbing locomotory behavior lipid biomass probing behavior vector manipulation

The hidden struggle of overworked urology residents“the hour”:The overlooked burnout,a narrative review

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UroPrecision 2024年第1期2卷 16-23页

作者： alain Mwamba Mukendi Department of Surgery Division of UrologyHelen Joseph HospitalUniversity of the WitwatersrandRossmoreJohannesburgSouth Africa

Burnout is a growing concern across numerous professions and industries *** has increased for many people since the onset of COVID-19 due to the stress,uncertainty,and changes brought on by the *** is also a significant issue in the field of medicine,particularly urology,where residents face long working hours and high workloads,leading to physical and mental health problems,as well as limited opportunities for rest and *** alarming trend highlights the need for more effective measures to address burnout and promote employee well-being and job satisfaction.A thorough search of electronic databases such as PubMed,Scopus,and Google Scholar was conducted to obtain pertinent articles using relevant *** articles were screened for relevance,with duplicates and irrelevant articles *** and critical review analysis was conducted on chosen articles,identifying key themes and contributing factors related to burnout in urology *** hidden struggle of overworked urology residents and their overlooked burnout represents a complex issue that requires systemic change and individual-level *** must prioritize employee well-being by providing adequate support and resources for managing ***,promoting effective leadership practices that prioritize resident well-being over any personal or institution recognitions or gains is *** steps will improve the quality of care while mitigating negative outcomes for residents.

关键词： awareness and mental health burnout hidden struggle leadership overwork residency urology

A novel responsive stabilizing Janus nanosilica as a nanoplugging agent in water-based drilling fluids for exploiting hostile shale environments

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Petroleum Science 2024年第2期21卷 1190-1210页

作者： alain Pierre Tchameni lv-Yan Zhuo lesly Dasilva Wandji Djouonkep Robert Dery Nagre lu-Xin Chen lin Zhao Chao Ma Bin-Qiang Xie College of Petroleum Engineering Yangtze UniversityWuhan430100HubeiChina Key laboratory of Drilling and Production Engineering for Oil and Gas HubeiChina lost Circulation Control laboratory National Engineering Laboratory for Petroleum Drilling EngineeringYangtze UniversityWuhan430100HubeiChina College of Petroleum Engineering Shandong Institute of Petroleum and Chemical TechnologyDongying257061ShandongChina Petroleum Engineer Research Institute of Petrochina Dagang Oilfield Tianjin300280China Department of Chemical Engineering Kumasi Technical UniversityP.O.Box 854KumasiGhana

Thermo-responsive nanocomposites have recently emerged as potential nanoplugging agents for shale stabilization in high-temperature water-based drilling fluids(WBDFs). However, their inhibitory properties have not been very effective in high-temperature drilling operations. Thermo-responsive Janus nanocomposites are expected to strongly interact with clay particles from the inward hemisphere of nanomaterials, which drive the establishment of a tighter hydrophobic membrane over the shale surface at the outward hemisphere under geothermal conditions for shale stabilization. This work combines the synergistic benefits of thermo-responsive and zwitterionic nanomaterials to synchronously enhance the chemical inhibitions and plugging performances in shale under harsh conditions. A novel thermoresponsive Janus nanosilica(TRJS) exhibiting zwitterionic character was synthesized, characterized,and assessed as shale stabilizer for WBDFs at high temperatures. Compared to pristine nanosilica(Si NP)and symmetrical thermo-responsive nanosilica(TRS), TRJS exhibited anti-polyelectrolyte behaviour, in which electrolyte ions screened the electrostatic attraction between the charged particles, potentially stabilizing nanomaterial in hostile shaly environments(i.e., up to saturated brine or API brine). Macroscopically, TRJS exhibited higher chemical inhibition than Si NP and TRS in brine, prompting a better capability to control pressure penetration. TRJS adsorbed onto the clay surface via chemisorption and hydrogen bonding, and the interactions became substantial in brine, according to the results of electrophoretic mobility, surface wettability, and X-ray diffraction. Thus, contributing to the firm trapping of TRJS into the nanopore structure of the shale, triggering the formation of a tight hydrophobic membrane over the shale surface from the outward hemisphere. The addition of TRJS into WBDF had no deleterious effect on fluid properties after hot-treatment at 190℃, implying that TRJ

关键词： Janus nanosilica Thermo-responsive copolymer Anti-polyelectrolyte effect Shale stabilizer Inhibition Plugging Drilling fluid