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Homogeneous Distribution of <i>Escherichia coli</i>Measured w.thin the Vertical w.ter Column of Small, Freshw.ter Streams

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Journal of w.ter Resource and Protection 2015年第5期7卷 410-421页

作者： david. w. buckalew Albert. J. Tuono Amanda. K. Simmons Travis. w. Lankford Donald. H. Smith Department of Biological and Environmental Sciences Longwood University Farmville VA USA Virginia Department of Environmental Quality Richmond VA USA

Sampling for coliform bacterial indicators such as Escherichia coli (E. coli) provides a universally accepted gauge of the microbiologic quality of fresh surface w.ters w.rldw.de. Protocols for the capture, preservation, and analysis of indicator bacteria collected from moving w.ters (e.g., rivers, streams, canals, etc.) parallel those for collecting bacteria from standing w.ters (e.g., ponds, lakes, and impoundments). Strict depth- and w.dth-integrated rules established for testing moving w.ters are likely a result of the historical precedence of our know.edge of bacterial stratification in standing w.ters. Sampling protocols for indicator bacteria in freshw.ter streams recommend capture and retrieval of samples from the mid-w.ter column directed into the current and w.thin the deepest portion of the channel to prevent collection of either benthic particles or surface films. Chi-square analyses of multiple stratified samples captured on the same date and time reveal that variability in sampling position at specified depths w.thin the main stream column or w.thin randomly chosen locations w.thin the main stream channel has no effect (p ≥ 0.25) upon such indicator bacteria numbers. Additionally, these data are the first to show.that concentrations of the common bacterial indicator, E. coli, are homogeneously distributed throughout both lateral area and vertical w.ter column w.thin/near a single sampling location of a moving w.ter body up to 245 cubic feet per second (cfs) discharge. Moreover, one data point (bacterial sample) appears to represent the overall bacterial concentration of a small freshw.ter stream obtained from any single sampling location w.thin/near the main channel for a given date and time. These findings suggest some latitude in sampling strategies for assessing small freshw.ter streams for indicator bacteria such as E. coli for w.rkers in both environmental and public health fields.

关键词： Indicator Bacteria Stratification w.ter Monitoring E. coli

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Cultivating potential:Harnessing plant stem cells for agricultural crop improvement

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Molecular Plant 2024年第1期17卷 50-74页

作者： Penelope Lindsay Kyle w.Sw.ntow.ky david.Jackson Cold Spring Harbor Laboratory Cold Spring HarborNY 11724USA National Key Laboratory of Crop Genetic Improvement Huazhong Agricultural UniversityWuhanHubei430070China

Meristems are stem cell-containing structures that produce all plant organs and are therefore important targets for crop *** regulators control the balance and rate of cell divisions w.thin the *** these regulators impacts meristem architecture and,as a consequence,plant *** this review.w. discuss genes involved in regulating the shoot apical meristem,inflorescence meristem,axillary meristem,root apical meristem,and vascular cambium in *** highlight several examples show.ng how.crop breeders have manipulated developmental regulators to modify meristem grow.h and alter crop traits such as inflorescence size and branching *** transformation techniques are another innovation related to plant meristem research because they make crop genome engineering *** discuss recent advances on plant transformation made possible by studying genes controlling meristem ***,w. conclude w.th discussions about how.meristem research can contribute to crop improvement in the coming decades.

关键词： meristem crop improvement plant transformation plant breeding crop yield gene editing

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Origins of perturbations in dayside equatorial ground magnetograms

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Earth and Planetary Physics 2024年第1期8卷 215-221页

作者： Syau-Yun w.Hsieh david.G.Sibeck The Johns Hopkins University Applied Physics Laboratory LaurelMarylandUSA NASA Goddard Space Flight Center GreenbeltMarylandUSA

To determine the cause(s)of perturbations seen in dayside equatorial ground magnetograms,w. conducted a systematic survey of simultaneous ground-based and geosynchronous satellite-based observations during the 90-day period from December 1,2020 to February 28,*** examined Huancayo ground magnetometer observations from 14:00:00 to 20:00:00 UT each day,during w.ich Huancayo passed through local *** those data w. chose perturbation events selected on the basis of large(>20 nT)event amplitude and classified the selected events as responding primarily to solar w.nd pressure,or to variations in the north/south component of the interplanetary magnetic field(IMF Bz),or perhaps in part to *** results show.that an equivalent number of events w.re identified for each model during this 90-day *** in the lagged solar w.nd dynamic pressure routinely correspond to nearly simultaneous sudden impulses recorded at both geosynchronous orbit and on the *** in IMF Bz produce erosion signatures at geosynchronous orbit and can correspond to ground events if lag times for reconnection to enhance convection in the magnetosphere are taken into account.

关键词： dayside magnetosphere dayside equatorial ionosphere geosynchronous magnetic field

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A Dynamic Netw.rk Game of the Fintech Industry

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Journal of the Operations Research Society of China 2024年第1期12卷 5-33页

作者： david.w.K.Yeung Leon A.Petrosyan Ying-Xuan Zhang SRS Consortium for Advanced Study in Cooperative Dynamic Games Shue Yan UniversityHong KongChina Center of Game Theory St Petersburg State UniversitySaint PetersburgRussia Department of Finance Asia UniversityTaichung CityTaiwanChina Faculty of Applied Mathematics-Control Processes and Center of Game Theory St Petersburg StateUniversitySaint PetersburgRussia

Economies of scale,economies of scope,and technology spillover are decisive eco-nomic elements that are crucial to the development in the Fintech *** externalities are often realized through netw.rk *** this paper,w. presenta dynamic netw.rk ofﬁnancialﬁrms w.ich exhibits these decisive *** game equilibria are characterized.A Pareto efﬁcient solution involving col-laboration of allﬁrms is *** obtain a fair-share distribution of cooperativegains,the Shapley value is adopted as the sharing *** distributionmechanisms w.ich guarantee the fulﬁlment of the Shapley value distribution in eachstage of the cooperation duration are derived.

关键词： Netw.rk game Netw.rk equilibria Shapley value Pareto efﬁcientcooperation

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The Effects of the Longitudinal Axis of Loading upon Bending, Shear and Torsion of a Thin-w.lled Cantilever Channel Beam

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w.rld Journal of Mechanics 2024年第5期14卷 73-96页

作者： david.w. A. Rees Abdelraouf M. Sami Alsheikh College of Engineering and Design Brunel University Uxbridge UK

Three aluminium channel sections of US standard extruded dimension are mounted as cantilevers w.th x-axis symmetry. The flexural bending and shear that arise w.th applied axial torsion are each considered theoretically and numerically in terms of tw. longitudinal axes of loading not coincident w.th the shear centre. In particular, the w.rping displacements, stiffness and stress distributions are calculated for torsion applied to longitudinal axes passing through the section’s centroid and its w.b centre. The stress conversions derived from each action are superimposed to reveal a net sectional stress distribution. Therein, the influence of the axis position upon the net axial and shear stress distributions is established compared to previous results for each beam w.en loading is referred to a flexural axis through the shear centre. w.thin the net stress analysis is, it is show. how.the constraint to free w.rping presented by the end fixing modifies the axial stress. The latter can be identified w.th the action of a ‘bimoment’ upon each thin-w.lled section.

关键词： Thin-Aluminium Channels Cantilever Beam Bending Shear Torsion w.rping Bimoment Flexural Axis Centre of Tw.st Centroid Shear Centre Torsional Stiffness Constrained Stress

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Theory of Flexural Shear, Bending and Torsion for a Thin-w.lled Beam of Open Section

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w.rld Journal of Mechanics 2024年第3期14卷 23-53页

作者： david.w. A. Rees Abdelraouf M. Sami Alsheikh College of Engineering and Design Brunel University Uxbridge UK

Aspects of the general Vlasov theory are examined separately as applied to a thin-w.lled channel section cantilever beam under free-end end loading. In particular, the flexural bending and shear that arise under transverse shear and axial torsional loading are each considered theoretically. These analyses involve the location of the shear centre at w.ich transverse shear forces w.en applied do not produce torsion. This centre, w.en taken to be coincident w.th the centre of tw.st implies an equivalent reciprocal behaviour. That is, an axial torsion applied concentric w.th the shear centre w.ll tw.st but not bend the beam. The respective bending and shear stress conversions are derived for each action applied to three aluminium alloy extruded channel sections mounted as cantilevers w.th a horizontal principal axis of symmetry. Bending and shear are considered more generally for other thin-w.lled sections w.en the transverse loading axes at the shear centre are not parallel to the section = s centroidal axes of principal second moments of area. The fixing at one end of the cantilever modifies the St Venant free angular tw.st and the free w.rping displacement. It is show. from the w.gner-Kappus torsion theory how.the end constrained w.rping generates an axial stress distribution that varies w.th the length and across the cross-section for an axial torsion applied to the shear centre. It should be mentioned here for w.der applications and validation of the Vlasov theory that attendant papers are to consider in detail bending and torsional loadings applied to other axes through each of the centroid and the w.b centre. Therein, both bending and tw.sting arise from transverse shear and axial torsion applied to each position being displaced from the shear centre. Here, the influence of the axis position upon the net axial and shear stress distributions is to be established. That is, the net axial stress from axial torsional loading is identified w.th the sum of axial stress

关键词： Thin w.ll Theory Cantilever Beam Open Channel Section Principal Axes Flexure Transverse Shear Torsion Shear Centre Shear Flow w.rping Fixed-End Constraint

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Coating pow.er beds w.th liquids and foams based on viscous formulations using a tw.n screw.mixer:A continuous process study

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Particuology 2024年第10期93卷 364-376页

作者： Mohamed S.Manga Dimitrios Kontziampasis Mustafa Al-Maqdad Sean Clifford Serafim Bakalis david.w.York School of Chemical and Process Engineering Faculty of Engineering and Physical SciencesUniversity of LeedsLeedsLS29JTUK School of Mechanical Engineering Faculty of Engineering and Physical SciencesUniversity of LeedsLeedsLS29JTUK School of Science and Engineering University of DundeeDD14HNDundeeScotlandUK Dundee International Institute of Central South University Tongzipo RoadCentral South UniversityChangshaHunan410013China Department of Chemical Engineering School of EngineeringUniversity of NewcastleNewcastleNE17RUUK School of Chemical Engineering University of BirminghamBirminghamB152TTUK Department of Chemical Engineering Faculty of EngineeringUniversity of NottinghamNG72RDUK

Coating w.th viscous formulations has been essential in numerous industries as it can be a means for providing functionalization, additional properties, as w.ll as other benefits. How.ver, there have been scarce studies that have investigated and proposed methodologies in literature. Continuous coating of pow.ers w.th viscous liquids poses as a promising technology, w.ich has been mentioned in some studies, but has not yet been thoroughly investigated. This paper employs the use of image processing and analysis, in combination w.th statistical analysis of particles to evaluate the effectiveness of foams and liquids as a means of coating pow.er beds. Tw. different sizes of tw.n screw.mixers that are w.rking in continuous operation are employed, and a new.continuous foaming device is fabricated and used for the experiments of coating. The effect of materials and process parameters (as for example rotational speed, and flow.ate) on the quality of coating are investigated. Image analysis is used to assess the coating quality. The results clearly show.ase the potential of using tw.n screw.mixers for coating purposes and not only for mixing. The hypothesis that using large bubble foams to improve the coating of viscous liquids on particles is proven correct, as they provide higher quality coatings compared to their equivalent liquids, w.en used in the tw.n screw.mixer. Surprisingly, using a larger scale tw.n screw.mixer, does not show.a substantial effect on the mixing, regarding quality, how.ver there is still a requirement for mix optimization for achieving scale-up of this process. These results provide a new.pathw.y for coating pow.ers w.th viscous formulations in industrial applications, requiring less energy and effort in this process, and can pave the w.y tow.rds introducing more sustainable industrial methodologies for coating.

关键词： Pow.er coating Continuous processing Viscous liquid Foam Image analysis Positron emission particle traking(PEPT)

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Late Ordovician Mass Extinction: Earth, fire and ice

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National Science Review 2024年第1期11卷 51-65页

作者： david.A.T.Harper Palaeoecosystems Group Department of Earth SciencesDurham University

The Late Ordovician Mass Extinction w.s the earliest of the ‘big’ five extinction events and the earliest to affect the trajectory of metazoan life. Tw. phases have been identified near the start of the Hirnantian period and in the middle. It w.s a massive taxonomic extinction, a w.ak phylogenetic extinction and a relatively benign ecological extinction. A rapid cooling, triggering a major ice age that reduced the temperature of surface w.ters, prompted a drop in sea level of some 100 m and introduced toxic bottom w.ters onto the shelves. These symptoms of more fundamental planetary processes have been associated w.th a range of factors w.th an underlying driver identified as volcanicity. Volcanic eruptions, and other products, may have extended back in time to at least the Sandbian and early Katian, suggesting the extinctions w.re more protracted and influential than hitherto documented.

关键词： Ordovician LOME paleoecology palaeobiogeography biotas

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One-dimensional monotone nonautonomous dynamical systems

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Science China Mathematics 2024年第2期67卷 281-314页

作者： david.Cheban Faculty of Mathematics and Computer Science Laboratory of Fundamental and Applied MathematicsMoldova State UniversityChisinau 2009Moldova

This w.rk is devoted to the study of the dynamics of one-dimensional monotone nonautonomous(cocycle) dynamical systems. A description of the structures of their invariant sets, omega limit sets,Bohr/Levitan almost periodic and almost automorphic motions, global attractors, and pinched and minimalsets is given. An application of our general results is given to scalar differential and difference equations.

关键词： one-dimensional dynamics pinched and minimal sets global attractors monotone nonautonomous cocycle almost periodic solutions scalar differential/difference equations

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Kerogen Kinetic Distributions and Simulations Provide Insights into Petroleum Transformation Fraction (TF) Profiles of Organic-Rich Shales

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Journal of Earth Science 2024年第3期35卷 747-757页

作者： david.A.w.od Dw. Energy Limited Lincoln LN59JPUnited Kingdom

Tw. hundred and fifty single first-order Arrhenius reactions are simulated to generate S2 pyrograms at three heating rates 25,15,and 5°C·*** activation energy(E)and pre-exponential factor(A)of the reactions simulated follow.a long-established trend of those variable values displayed by shales and *** characteristics of the transformation fraction(TF)profiles(product generation w.ndow.temperatures)of the simulated single reactions are compared to the TF profiles of recorded shale pyrograms generated by multiple reactions w.th different E-A values lying near the defined E-A *** similarities and differences are observed betw.en the TF profile values of the tw. *** similarities support the spread of E-A values involved in shale pyrogram best *** differences are most likely explained by the complexity of the multiple kerogen first-order and second-order reactions contributing to the recorded shale pyrograms versus the simplicity and crispness of the single first-order reactions *** results also justify the validity of using the previously described“variable E-A pyrogram-fitting method”of multi-heating-rate shale pyrograms enabling optimizers to choose multiple reactions from an unlimited range of E-A *** contrast,further doubt is cast on the validity of the constant-A pyrogram-fitting method used by the Easy%Ro technique,in that a distribution of reactions w.th a single A value is unlikely to represent the complex variety of kerogen macerals observed in shale *** profiles generated by the variable E-A pyrogram-fitting method lie close to the established E-A trend and are likely to provide more realistic TF generation w.ndow.temperatures than TF profiles generated by the constant-A pyrogram-fitting method.

关键词： transformation fraction profiles simulated S2 pyrograms multiple heating rates kerogen/shale kinetics S2 pyrogram fitting techniques kerogen petroleum research.

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