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Influence of railway wheel tread damage on wheel-rail impact loads and the durability of wheelsets

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Railway Engineering Science 2024年第1期32卷 20-35页

作者： Michele Maglio Tore Vernersson Jens c.O.nielsen Anders Ekberg Elena Kabo cHARMEc Department of Mechanical and Maritime SciencesChalmers University of TechnologySE‑41296 GothenburgSweden

Dynamic wheel-rail contact forces induced by a severe form of wheel tread damage have been measured by a wheel impact load detector during full-scale field tests at different vehicle *** on laser scanning,the measured three-dimensional damage geometry is employed in simulations of dynamic vehicle-track interaction to calibrate and verify a simulation *** relation between the magnitude of the impact load and various operational parameters,such as vehicle speed,lateral position of wheel-rail contact,track stiffness and position of impact within a sleeper bay,is *** calibrated model is later employed in simulations featuring other forms of tread damage;their effects on impact load and subsequent fatigue impact on bearings,wheel webs and subsurface initiated rolling contact fatigue of the wheel tread are *** results quantify the effects of wheel tread defects and are valuable in a shift towards condition-based maintenance of running gear,and for general assessment of the severity of different types of railway wheel tread damage.

关键词： Wheel tread damage Rolling contact fatigue cluster Field measurements Dynamic vehicle-track interaction Wheel-rail impact load Wheelset durability

climate refugia along Lake Superior’s shores:disjunct arctic-alpine plants rely on cool shoreline temperatures but are restricted to highly exposed habitat under climate warming

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Journal of Plant Ecology 2024年第4期17卷 23-41页

作者： Ashley Hillman Scott E.nielsen Department of Renewable Resources University of AlbertaEdmontonAB T6G 2R3Canada

climate refugia can serve as a remnant habitat or stepping stones for species dispersal under climate *** largest freshwater lake by surface area,Lake Superior,USA and canada,serves as a model system for understanding cooling-mediated local refugia,as its cool water temperatures and wave action have maintained shoreline habitats suitable for southern disjunct populations of arctic-alpine plants since ***,we seek to explain spatial patterns and environmental drivers of arctic-alpine plant refugia along Lake Superior’s shores,and assess future risk to refugia under moderate(+3.5℃)and warmest(+5.7℃)climate warming ***,we examined how the interactive effects of summer surface water temperatures and wind affected onshore temperatures,resulting in areas of cooler ***,we developed an ecological niche model for the presence of disjunct arctic-alpine refugia(pooling 1253 occurrences from 58 species)along the lake’s ***,we fit species distribution models for 20 of the most common arctic-alpine disjunct species and predicted presence to identify refugia ***,we used the two climate warming scenarios to predict changes in the presence of refugia and disjunct *** type,elevation above water,inland distance,July land surface temperature from MODIS/Terra satellite and near-shore depth of water were the best predictors of disjunct ***,we predicted 2236 km of the shoreline(51%)as disjunct refugia habitat for at least one species under current conditions,but this was reduced to 20% and 7% with moderate(894 km)and warmest(313 km)climate change projections.

关键词： climate refugia disjunct populations lake effect Lake Superior species distribution models

Transmission matrices used in epidemiologic modelling

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Infectious Disease Modelling 2024年第1期9卷 185-194页

作者： M.Bekker-nielsen Dunbar centre for Research on Pandemics&Society OsloMet–Oslo Metropolitan UniversityHG536Holbergs gate 1Oslo0166Norway

Mixing matrices are included in infectious disease models to reflect transmission opportunities between population *** matrices were originally constructed on the basis of theoretical considerations and most of the early work in this area originates from research on sexually transferred diseases in the 80s,in response to *** work in the 90s populated these matrices on the basis of survey data gathered to capture transmission risks for respiratory *** provide an overview of developments in the construction of matrices for capturing transmission opportunities in *** transmission matrices are useful for epidemiologic modelling to capture within and between stratum transmission and can be informed from theoretical mixing assumptions,informed by empirical evidence gathered through investigation as well as generated on the basis of *** to summary measures and threshold conditions are also provided.

关键词： Disease transmission Mixing matrix Social contact Index of disassortativity

Electrogenic sulfur oxidation mediated by cable bacteria and its ecological effects

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Environmental Science and Ecotechnology 2024年第4期20卷 34-41页

作者： Zhenyu Wang Leonid Digel Yongqiang Yuan Hui Lu Yonggang Yang carsten Vogt Hans-Hermann Richnow Lars Peter nielsen Department of Isotope Biogeochemistry Helmholtz Centre for Environmental Research e UFZPermoserstraße 1504318LeipzigGermany center for Electromicrobiology Department of BiologyAarhus UniversityDK-8000AarhusDenmark Key Laboratory of Karst Georesources and Environment Ministry of EducationCollege of Resources and Environmental EngineeringGuizhou UniversityGuiyang550025China School of Environmental Science and Engineering Sun Yat-Sen UniversityGuangzhou510006China School of Life Science and Engineering Foshan UniversityFoshan528225China State Key Laboratory of Applied Microbiology Southern china Institute of MicrobiologyGuangdong Academy of SciencesGuangzhou510007China

At the sediment-water interfaces,filamentous cable bacteria transport electrons from sulfide oxidation along their filaments towards oxygen or nitrate as electron *** multicellular bacteria belonging to the family Desulfobulbaceae thus form a biogeobattery that mediates redox processes between multiple *** bacteria were first reported in *** the past years,cable bacteria have been found to be widely distributed across the *** potential in shaping the surface water environments has been extensively studied but is not fully *** this review,the biogeochemical characteristics,conduction mechanisms,and geographical distribution of cable bacteria,as well as their ecological effects,are systematically reviewed and *** insights for understanding and applying the role of cable bacteria in aquatic ecology are summarized.

关键词： cable bacteria Electrogenic sulfur oxidation Long-distance electron transfer Aquatic ecology

Metabolic collaboration between cells in the tumor microenvironment has a negligible effect on tumor growth

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The Innovation 2024年第2期5卷 107-114页

作者： Johan Gustafsson Fariba Roshanzamir Anders Hagnestål Sagar M.Patel Oseeyi I.Daudu Donald F.Becker Jonathan L.Robinson Jens nielsen Department of Life Sciences Chalmers University of TechnologySE-41296 GothenburgSweden Hagnesia AB SE-43854 HindåsSweden Department of Biochemistry and Redox Biology center University of Nebraska-LincolnLincolnNE 68588USA BioInnovation Institute DK2200 CopenhagenDenmark

The tumor microenvironment is composed of a complex mixture of different cell types interacting under conditions of nutrient deprivation,but the metabolism therein is not fully understood due to difficulties in measuring metabolic fluxes and exchange of metabolites between different cell types in ***-scale metabolic modeling enables estimation of such exchange fluxes as well as an opportunity to gain insight into the metabolic behavior of individual cell ***,we estimated the availability of nutrients and oxygen within the tumor microenvironment using concentration measurements from blood together with a metabolite diffusion *** addition,we developed an approach to efficiently apply enzyme usage constraints in a comprehensive metabolic model of human *** combined modeling reproduced severe hypoxic conditions and the Warburg effect,and we found that limitations in enzymatic capacity contribute to cancer cells’preferential use of glutamine as a substrate to the citric acid ***,we investigated the common hypothesis that some stromal cells are exploited by cancer cells to produce metabolites useful for the cancer *** identified over 200 potential metabolites that could support collaboration between cancer cells and cancer-associated fibroblasts,but when limiting to metabolites previously identified to participate in such collaboration,no growth advantage was *** work highlights the importance of enzymatic capacity limitations for cell behaviors and exemplifies the utility of enzyme-constrained models for accurate prediction of metabolism in cells and tumor microenvironments.

关键词： metabolism effect limitations

Light sheet microscope scanning of biointegrated microlasers for localized refractive index sensing

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Photonics Research 2024年第8期12卷 1673-1680页

作者： ROSS c.cOWIE MARcEL ScHUBERT SUPA School of Physics and AstronomyUniversity of St AndrewsSt AndrewsUK Humboldt centre for Nano and Biophotonics Department of ChemistryUniversity of CologneCologneGermany

Whispering gallery mode(WGM)microlasers are highly sensitive to localized refractive index changes allowing to link their emission spectrum to various chemical,mechanical,or physical *** recently found applications in biological studies within single cells,in three-dimensional samples such as multicellular spheroids,or in ***,detailed studies of biological samples also need to account for the structural heterogeneity of tissues and live animals,therefore requiring a combination of high-resolution microscopy and laser ***,we design and construct a light sheet fluorescence microscope with a coupled spectrometer for use in microlaser studies for combined high-resolution,high-speed imaging and WGM spectral *** light sheet illumination profile and the decoupled geometry of excitation and emission hereby directly affect the lasing and sensing properties,mainly through geometric constraints and by light coupling *** demonstrate the basic working principle of microlaser spectroscopy under light sheet excitation and measure the absolute refractive index within agarose and in zebrafish tail muscle *** further analyze the light coupling conditions that lead to the occurrence of two separate oscillation *** so-called cross modes can be scanned around the entire microlaser surface,which allows to estimate a surface-averaged refractive index profile of the microlaser environment.

关键词： refractive index excitation

Important step towards an understanding of the exotic Z_(c)(3900)

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Science china(Physics,Mechanics & Astronomy) 2024年第9期67卷 199-200页

作者： c.Hanhart Institute for Advanced Simulation Forschungszentrum JulichJilich D-52425Germany

The Standard Model of particle physics,which contains the field theories for the electro-weak interaction(QED)and the strong interaction(QcD),is an extremely successful theory describing a huge variety of phenomena at... 详细信息

关键词： interaction atomic describing

A toast to a zebrafish germ cell induction cocktail

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Science china(Life Sciences) 2024年第6期67卷 1314-1315页

作者： Mary c.Mullins Department of cell and Developmental Biology University of Pennsylvania Perelman School of MedicinePhiladelphia 19104USA

The zebrafish field is ringing in the new year with a publication from Yonghua Sun's laboratory(Wang et al.,2023)of a cocktail of germline factors that can induce all cells of the zebrafish embryo into primordial germ cells(PGcs)at phenomenal *** major advance is not only of great interest to germ cell biologists,but it has important applications to the entire zebrafish field,as shown in Wang et al.(2023).

关键词： fish zebra field

Performance of evolutionary optimized machine learning for modeling total organic carbon in core samples of shale gas fields

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Petroleum 2024年第1期10卷 150-164页

作者： Leonardo Goliatt c.M.Saporetti L.c.Oliveira E.Pereira Department of computational and Applied Mechanics Federal University of Juiz de ForaJuiz de ForaBrazil Department of computational Modeling Polytechnic InstituteRio de Janeiro State UniversityNova FriburgoBrazil Petrobras Rio de JaneiroBrazil Department of Stratigraphy and Paleontology Rio de Janeiro State UniversityRio de JaneiroBrazil

Rock samples'TOc content is the best indicator of the organic matter in source *** origin rock samples’analysis is used to calculate it manually by *** method requires time and resources because it relies on samples from many well intervals in source ***,research has been done to aid this *** learning algorithms can estimate total organic carbon instead of well logs and stratigraphic *** light of these efforts,the current work present a study on automating the total organic carbon estimation using machine learning approaches improved by an evolutionary methodology to give the model flexibility and *** algorithms,differential evolution,particle swarm optimization,grey wolf optimization,artificial bee colony,and evolution strategies were used to improve machine learning models to predict *** six metaheuristics were integrated into four machine learning methods:extreme learning machine,elastic net linear model,linear support vector regression,and multivariate adaptive regression *** samples from the YuDong-Nan shale gas field,located in the Sichuan basin,were used to evaluate the hybrid *** findings show that combining machine learning models with an evolutionary algorithms in a hybrid fashion produce flexible models that accurately predict *** results show that,independent of the metaheuristic used to guide the model selection,optimized extreme learning machines attained the best performance scores according to six *** hybrid models can be used in exploratory geological research,particularly for unconventional oil and gas resources.

关键词： Total organic carbon Hybrid models Automated machine learning Evolutionary algorithms Geology