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A planet in transition:The onset of plate tectonics on earth between 3 and 2 Ga?

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Geoscience Frontiers 2018年第1期9卷 51-60页

作者： kent C.Condie Department of earth and environmental science New Mexico Tech

Many geological and geochemical changes are recorded on earth between 3 and 2 *** the more important of these are the following:(1)increasing proportion of basalts with"arc-like"mantle sources;(2)an increasing abundance of basalts derived from enriched(eM)and depleted(DM)mantle sources;(3)onset of a Great Thermal Divergence in the mantle;(4)a decrease in degree of melting of the mantle;(5)beginning of large lateral plate motions;(6)appearance of eclogite inclusions in diamonds;(7)appearance and rapid increase in frequency of collisional orogens;(8)rapid increase in the production rate of continental crust as recorded by zircon age peaks;(9)appearance of ophiolites in the geologic record,and(10)appearance of global LIP(large igneous province)events some of which correlate with global zircon age *** of these changes may be tied directly or indirectly to cooling of earth's mantle and corresponding changes in convective style and the strength of the lithosphere,and they may record the gradual onset and propagation of plate tectonics around the *** further understand the changes that occurred between 3 and 2 Ga,it is necessary to compare rocks,rock associations,tectonics and geochemistry during and between zircon age *** of peak and inter-peak basalts and TTGs needs to be evaluated in terms of geodynamic models that predict the existence of an episodic thermal regime between stagnant-lid and plate tectonic regimes in early planetary evolution.

关键词： Plate tectonics Zircon age peaks Mantle evolution stagnant lid Continental crust LIP events

An assessment of coal pillar system stability criteria based on a mechanistic evaluation of the interaction between coal pillars and the overburden

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International Journal of Mining science and Technology 2017年第1期27卷 9-15页

作者： Reed Guy Mctyer kent Frith Russell Mine Advice Pry Ltd NewcastleNSW 2322Australia

Coal pillar design has historically assigned a factor of safety(Fo s) or stability factor(sF) according to their estimated strength and the assumed overburden load acting on them. Acceptable Fo s values have been assigned based on past mining experience or a statistical link between Fo s and probability of failure(Po F). Pillar width-to-height(w/h) ratio has long been established as having a material influence on both pillar strength and its potential failure mode. However, there has been significant disagreement on using both factor of safety(Fo s) and w/h as part of pillar system stability criterion, as compared to using Fo s in isolation. This paper will argue that there are valid technical reasons to bring w/h ratio into system stability criteria(other than its influence on pillar strength), as it is related to the post-failure stiffness of the pillar, as measured in situ, and its interaction with overburden stiffness. When overburden stiffness is also brought into pillar system stability considerations, two issues emerge. The first is the width-todepth(W/D) ratio of the panel and whether it is sub-critical or super-critical from a surface subsidence perspective. The second relates to a re-evaluation of pillar Fo s based on whether the pillar is in an elastic or non-elastic(i.e., post-yield) state in its as-designed condition, as this is relevant to maintaining overburden stiffness at the highest possible level. The significance of the model is the potential to maximise both reserve recovery and mining efficiencies without any discernible increase in geotechnical risk, particularly in thick seams and higher depth of cover mining situations. At a time when mining economics are, at best, marginal, removing potentially unnecessary design conservatism is of interest to all mine operators and is an important topic for discussion amongst the geotechnical community.

关键词： Coa] pillars stability Overburden Post-failure behaviour stability criteria

On the Bifurcations and Multiple endemic states of a single strain HIV Model Dedicated to Professor Toshikazu sunada on the Occasion of his 60th Birthday

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Acta Mathematicae Applicatae sinica 2014年第4期30卷 913-930页

作者： Lindley kent M.FAINA Lorna s.ALMOCeRA Polly W.sY College of Arts and sciences University of the Philippines Visayas Natural sciences and Mathematics Division University of the Philippines VisayasCebu College Institute of Mathematics University of the Philippines

The dynamics of a single strain HIV model is studied. The basic reproduction number R0 used as a bifurcation parameter shows that the system undergoes transcritical and saddle-node bifurcations. The usual threshold unit value of R0 does not completely determine the eradication of the disease in an HIV infected person. In particular, a sub-threshold value Rc is established which determines the system＇s number of endemic states： multiple if Rc 〈 Ro 〈 1, only one if Rc=Ro = 1, and none if R0 〈 Rc 〈 1.

关键词： single strain HIV model multiple endemic states transcritical bifurcation s^idle-node bifurcation hysteresis

Difference in BOF slag splashing in Us and China

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Journal of Iron and steel Research International 2001年第1期8卷 1-5页

作者： CHeN Wei-qing kent Peaslee University of science and Technology Beijing University of Missouri-Rolla

some differences in slag splashing between BOF steel works in Us and China were investigated. The slag composition,melting point, and mineralogical phases of final slags from both countries were studied. The control o... 详细信息

关键词： slag splashing BOF melting point mineralogical phases superheat

Measuring user preferences and behaviour in a topographic immersive virtual environment(TopoIVe)of 2D and 3D urban topographic data

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International Journal of Digital earth 2021年第12期14卷 1835-1867页

作者： Łukasz Halik Alexander J.kent Department of Cartography and Geomatics Adam Mickiewicz UniversityPoznańPoland school of Psychology and Life sciences Canterbury Christ Church UniversityCanterburyUK

This paper investigates user preferences and behaviour associated with 2D and 3D modes of urban representation within a novel Topographic Immersive Virtual environment(TopoIVe)created from official 1:10,000 *** participants were divided into two groups:the first were given a navigational task within a simulated city and the second were given the freedom to explore it.A Head-Mounted Display(HMD)Virtual Reality(VR)app allowed participants to switch between 2D and 3D representations of buildings with a remote controller and their use of these modes during the experiment was *** performed mental rotation tests before entering the TopoIVe and were interviewed afterwards about their experiences using the *** results indicate that participants preferred the 3D mode of representation overall,although preference for the 2D mode was slightly higher amongst those undertaking the navigational task,and reveal that different wayfinding solutions were adopted by participants according to their ***,the findings suggest that users exploit different aspects of 2D and 3D modes of visualization in their wayfinding strategy,regardless of their *** potential to combine the functionality of 2D and 3D modes therefore offers substantial opportunities for the development of immersive virtual reality products derived from topographic datasets.

关键词： Virtual reality(VR) immersive virtual environment(IVe) 2D versus 3D wayfinding topographic data

Growth factor delivery using extracellular matrix-mimicking substrates for musculoskeletal tissue engineering and repair

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Bioactive Materials 2021年第7期6卷 1945-1956页

作者： Robert C.H.Gresham Chelsea s.Bahney J.kent Leach UC Davis Department of Biomedical EngineeringDavisCAUSA steadman Phillippon Research Institute VailCOUSA UCsF Orthopaedic Trauma Institute San FranciscoCAUSA UC Davis Health Department of Orthopaedic SurgeryDavisCAUSA

Therapeutic approaches for musculoskeletal tissue regeneration commonly employ growth factors(GFs)to influence neighboring cells and promote migration,proliferation,or *** promising results in preclinical models,the use of inductive biomacromolecules has achieved limited success in translation to the *** field has yet to sufficiently overcome substantial hurdles such as poor spatiotemporal control and supraphysiological dosages,which commonly result in detrimental side *** presentation and retention of biomacromolecules is regulated by the extracellular matrix(eCM),which acts as a reservoir for GFs via electrostatic *** in the manipulation of extracellular proteins,decellularized tissues,and synthetic eCM-mimetic applications across a range of biomaterials have increased the ability to direct the presentation of *** application of biomaterial technologies utilizing eCM mimetics increases tissue regeneration without the reliance on supraphysiological doses of inductive *** review describes recent strategies to manage GF presentation using eCM-mimetic substrates for the regeneration of bone,cartilage,and muscle.

关键词： Growth factor extracellular matrix spatiotemporal control Tissue engineering Affinity

Ophiolites:Identification and tectonic significance in space and time

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Geoscience Frontiers 2023年第6期14卷 380-385页

作者： kent C.Condie Robert J.stern Department of earth&environmental science New Mexico Institute of Mining and TechnologySocorroNM 87801USA Geosciences Department University of Texas at DallasRichardsonTX 75080USA

Ophiolites are fragments of oceanic lithosphere that are produced at spreading centers at ocean ridges,back arc basins,or forearcs during subduction initiation,and are key indicators of plate *** it is widely agreed that ophiolites are remnants of oceanic crust and associated depleted mantle preserved in orogens,the recognition of ophiolites and their tectonic significance is still a topic of discussion and *** propose that ophiolites can be recognized in the geologic record by some combination of genetically related pillow basalt,layered gabbro,sheeted dykes,podiform chromite,harzburgite or/and *** igneous rocks have either ocean-ridge basalt or immature oceanic arc basalt chemical *** a scoring system of 1–11 for ophiolite confidence level,scores of8 are considered confident,6–8 probable,andestionable or unlikely *** ophiolites with scores6 areest confident ophiolite(score of 8)is the Zunhua ophiolite in eastern China at 2550 Ma,and the oldest well documented sheeted dykes occur in the Jormua and Purtuniq ophiolites at 2000–1950 *** do not become geographically widespread until after 900 Ma,and most ophiolites of all ages formed in a forearc(subduction initiation)tectonic *** ophiolite production requires plate tectonics,subduction must have begun at least locally by 2700 Ma but did not become widespread until after 2000 *** abundance of ophiolites after 900 Ma may reflect better preservation of subduction-related ophiolites,or to an increasing global network of interconnected *** frequency peaks in the geologic record partially reflect geographic regions where ophiolites have been extensively studied rather than monitoring the production rate of ophiolites,but the scarcity of>900 Ma ophiolites is probably real.

关键词： Ophiolite Plate tectonics subduction initiation Forearc Ocean ridge Tectonic setting supercontinent

Increased mutant KRAs gene dosage drives pancreatic cancer progression: evidence for wild-type KRAs as a tumor suppressor?

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Hepatobiliary surgery and Nutrition 2018年第5期7卷 403-405页

作者： Oliver A. kent Princess Margaret Cancer Centre University Health Network Toronto Medical Discovery Tower Toronto Canada

RAs genes are most commonly associated with gain-of function mutations that promote oncogenic behavior. Activating mutations in KRAs occur in 90–95% cases of pancreatic ductal adenocarcinoma (PDAC) a deadly and highly metastatic disease. Currently the fourth leading cause of cancer death in the United states, PDAC presents with a dismal 5-year survival rate of less than 5% (1).

关键词： KRAs dosage cancer

Greenhouse gases fluxes and soil thermal properties in a pasture in central Missouri

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Journal of environmental sciences 2010年第7期22卷 1029-1039页

作者： Nsalambi Vakanda Nkongolo shane Johnson kent schmidt Frieda eivazi Department of Agriculture and environmental sciences College of Agriculture and Natural Science Lincoln University Harvard Forest Faculty of Arts and Sciences Harvard University

Fluctuations of greenhouse gases emissions and soil properties occur at short spatial and temporal scales, however, results are often reported for larger scales studies. We monitored CO2, CH4, and N2O fluxes and soil temperature （T）, thermal conductivity （K）, resistivity （R） and thermal diffusivity （D） from 2004 to 2006 in a pasture. soil air samples for determination of CO2, CH4 and N2O concentrations were collected from static and vented chambers and analyzed within two hours of collection with a gas chromatograph. T, K, R and D were measured in-situ using a KD2 probe. soil samples were also taken for measurements of soil chemical and physical properties. The pasture acted as a sink in 2004, a source in 2005 and again a sink of CH4 in 2006. CO2 and CH4 were highest, but N2O as well as T, K and D were lowest in 2004. Only K was correlated with C02 in 2004 while T correlated with both N2O （r = 0.76, p = 0.0001） and CO2 （r = 0.88, p = 0.0001） in 2005. In 2006, all gases fluxes were significantly correlated with T, K and R when the data for the entire year were considered. However, an in-depth examination of the data revealed the existence of month-to-month shifts, lack of correlation and differing spatial structures. These results stress the need for further studies on the relationship between soil properties and gases fluxes. K and R offer a promise as potential controlling factors for greenhouse gases fluxes in this pasture.

关键词： greenhouse gases soil thermal properties fluxes