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人膝关节软骨:3.0T在体多元T2成像分析

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国际医学放射学杂志 2016年第1期 69-70页

作者： F.Liu K.W.Choi A.Samsonov r.g.spencer J.J.Wilson W.F.Block 牡丹 Department of Medical Physics Wisconsin Institutes for Medical Research

摘要目的应用单次激发多元驱动平衡（mcDESPOT）技术观察无症状志愿者和骨性关节炎病人的T1和T2像,比较膝关节软骨的多元T2参数。方法此项前瞻性研究得到了伦理委员会的批准,所有受试者均收到书面通知。对13名正常志愿者及14例骨性关节... 详细信息

摘要目的应用单次激发多元驱动平衡（mcDESPOT）技术观察无症状志愿者和骨性关节炎病人的T1和T2像,比较膝关节软骨的多元T2参数。方法此项前瞻性研究得到了伦理委员会的批准,所有受试者均收到书面通知。对13名正常志愿者及14例骨性关节炎病人行mc DESPOT序列成像。分别测量软骨的单元T2(T2 single)值、快速弛豫水元T2(T2 F)值、慢速弛豫水元T2(T2 s)值及快速弛豫水元T2分数（FF）。利用Wilcoxon秩和检验和多参数线性回归模型比较两组间mc DESPOT参数的差异。利用受试者操作特征曲线分析评估mc DESPOT在膝关节8个软骨分段中鉴别正常与退变软骨

关键词：膝关节软骨病人 T2 骨性关节炎

Heterogeneity of mature oligodendrocytes in the central nervous system

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Neural regeneration research 2025年第5期20卷 1336-1349页

作者： Chao Weng Adam M.r.groh Moein Yaqubi Qiao-Ling Cui Jo Anne Stratton g.r.Wayne Moore Jack P.Antel Neuroimmunology Unit Montreal Neurological Institute-HospitalDepartment of Neurology and NeurosurgeryMcGill UniversityMontrealQCCanada Department of Neurology Renmin Hospital of Wuhan UniversityWuhanHubei ProvinceChina

Mature oligodendrocytes form myelin sheaths that are crucial for the insulation of axons and efficient signal transmission in the central nervous *** evidence has challenged the classical view of the functionally static mature oligodendrocyte and revealed a gamut of dynamic functions such as the ability to modulate neuronal circuitry and provide metabolic support to *** the recognition of potential heterogeneity in mature oligodendrocyte function,a comprehensive summary of mature oligodendrocyte diversity is *** delve into early 20th-century studies by robertson and río-Hortega that laid the foundation for the modern identification of regional and morphological heterogeneity in mature ***,recent morphologic and functional studies call into question the long-assumed homogeneity of mature oligodendrocyte function through the identification of distinct subtypes with varying myelination ***,modern molecular investigations,employing techniques such as single cell/nucleus rNA sequencing,consistently unveil at least six mature oligodendrocyte subpopulations in the human central nervous system that are highly transcriptomically diverse and vary with central nervous system *** and disease related mature oligodendrocyte variation denotes the impact of pathological conditions such as multiple sclerosis,Alzheimer's disease,and psychiatric ***,caution is warranted when subclassifying mature oligodendrocytes because of the simplification needed to make conclusions about cell identity from temporally confined *** studies leveraging advanced techniques like spatial transcriptomics and single-cell proteomics promise a more nuanced understanding of mature oligodendrocyte *** research avenues that precisely evaluate mature oligodendrocyte heterogeneity with care to understand the mitigating influence of species,sex,central nervous system region,age,and disease,

关键词： aging central nervous system diseases electron microscopy heterogeneity immunohistochemistry myelin sheath natural history neuroglia oligodendroglia single-cell gene expression analysis

Permian–Triassic Charophytes: Distribution, Biostratigraphy and Biotic Events

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Journal of Earth Science 2018年第4期29卷 778-793页

作者： spencer g Lucas New Mexico Museum of Natural History 1801 Mountain Road N. W. Albuquerque New Mexico 87104 USA

Permian charophytes are known from the Ukraine, russia, Kazakhstan, germany, Saudi Arabia, China, the USA, Brazil, Paraguay and India. Most of these records are of Middle- Late Permian Age and are the basis of local biostratigraphic zonation in southern russia and China. Development of a robust Permian charophyte biostratigraphy will require a more extensive record. Triassic charopbytes are known from germany, Sweden, Poland, Slovenia, Bulgaria, the Ukraine, russia, Morocco, Congo, the USA, Argentina, Kazakhstan and China. This encompasses records from all Triassic stages and has been the basis of detailed biostratigraphic zonation in southern russia-Kazakhstan-eastern Europe. Permian and Triassic charophyte biostratigraphy at the level of genus does not provide detailed correlations beyond local or regional schemes. Nevertheless, it does identify some important evolutionary datums that constrain the timing of important biotic events in the Permian-Triassic evolutionary history of the Charophyta, including：（1） Early Permian extinction of the Palaeocharaceae; （2） Late Permian extinction of the ＂Trochiliscales＂（Moellerinales）; （3） Carboniferous origin of the paraphyletic Porocharaceae, soon followed during the Permian by the origin of the multicellular basal plate; and （4） an important generic turnover of charophytes across the Triassic-Jurassic boundary, though there are insufficient data to identify this as a mass extinction.

关键词： Permian Triassic charophytes biostratigraphy biotic events.

An SPH Framework for Earthquake-Induced Liquefaction Hazard Assessment of geotechnical Structures

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Computer Modeling in Engineering & Sciences 2025年第1期142卷 251-277页

作者： Sourabh Mhaski g.V.ramana Department of Civil Engineering Indian Institute of Technology DelhiNew Delhi110016India

Earthquake-induced soil liquefaction poses significant risks to the stability of geotechnical structures *** understanding of the liquefaction triggering,and the post-failure large deformation behaviour is essential for designing resilient *** present study develops a Smoothed Particle Hydrodynamics(SPH)framework for earthquake-induced liquefaction hazard assessment of geotechnical *** coupled flowdeformation behaviour of soils subjected to cyclic loading is described using the PM4Sand model implemented in a three-phase,single-layer SPH framework.A staggered discretisation scheme based on the stress particle SPH approach is adopted to minimise numerical inaccuracies caused by zero-energy modes and tensile ***,non-reflecting boundary conditions for seismic analysis of semi-infinite soil domains using the SPH method are *** numerical framework is employed for the analysis of cyclic direct simple shear test,seismic analysis of a level ground site,and liquefaction-induced failure of the Lower San Fernando *** agreement for liquefaction triggering and post-failure behaviour demonstrates that the SPH framework can be utilised to assess the effect of seismic loading on field-scale geotechnical *** present study also serves as the basis for future advancements of the SPH method for applications related to earthquake geotechnical engineering.

关键词： Earthquake seismic liquefaction stress particle PM4Sand smoothed particle hydrodynamics(SPH)

Machine Learning Techniques in Predicting Hot Deformation Behavior of Metallic Materials

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Computer Modeling in Engineering & Sciences 2025年第1期142卷 713-732页

作者： Petr Opela Josef Walek Jaromír Kopecek Department of Metallurgical Technologies Faculty of Materials Science and TechnologyVSB–Technical University of OstravaOstrava70800Czech Republic FZU—Institute of Physics of the Czech Academy of Sciences Prague18200Czech Republic

In engineering practice,it is often necessary to determine functional relationships between dependent and independent *** relationships can be highly nonlinear,and classical regression approaches cannot always provide sufficiently reliable ***,Machine Learning(ML)techniques,which offer advanced regression tools to address complicated engineering issues,have been developed and widely *** study investigates the selected ML techniques to evaluate their suitability for application in the hot deformation behavior of metallic *** ML-based regression methods of Artificial Neural Networks(ANNs),Support Vector Machine(SVM),Decision Tree regression(DTr),and gaussian Process regression(gPr)are applied to mathematically describe hot flow stress curve datasets acquired experimentally for a medium-carbon *** the gPr method has not been used for such a regression task before,the results showed that its performance is the most favorable and practically unrivaled;neither the ANN method nor the other studied ML techniques provide such precise results of the solved regression analysis.

关键词： Machine learning gaussian process regression artificial neural networks support vector machine hot deformation behavior

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

Paleosols of the upper Paleozoic Sangre de Cristo Formation,north-central New Mexico:record of early Permian palaeoclimate in tropical Pangaea

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Journal of Palaeogeography 2017年第2期6卷 144-161页

作者： Lawrence H. Tanner spencer g. Lucas Department of Biological Sciences Le Moyne CollegeSyracuseNY 13214USA New Mexico Museum of Natural History 1801 Mountain Road N.W.AlbuquerqueNM 87014USA

The lower Permian(Wolfcampian) Sangre de Cristo Formation of northern New Mexico consists of silty mudstones and laterally discontinuous sandstones deposited on an aggrading alluvial ***,mudstones display a variety of pedogenic *** mudstone fabrics vary from platy to prismatic;some beds display prominent pedogenic ***-colored root traces are common throughout the section,as are calcareous nodules,which vary from small bodies with diffuse boundaries to vertically stacked,discrete,cm-scale nodules(rhizocretions),and less commonly form coalescing *** occur only in the lower portion of the ca.90-m measured *** of the mudstone beds contain calcretes that are immature(calcic Protosols to calcic Argillisols),but the lower to middle portion of the section also contains mature calcrete horizons(argillic Calcisols and Calcisols).Intercalated micritic limestone beds with sharp contacts containing root traces,are of laterally variable thickness and grade to nodular *** are interpreted as floodplain pond carbonates that have undergone pedogenic alteration(palustrine limestones),indicating long periods of exposure under strongly seasonal climatic *** isotopic composition of the pedogenic carbonate displays a substantial range of values,but most of the range of variation in isotopic composition is accounted for by isotopically heavier carbonate(both carbon and oxygen) precipitated in shallow ponds subject to intense pedogenic reworking(palustrine carbonate).During the early Permian,northern New Mexico was situated in a near equatorial position(ca.4° N).The overall character of the paleosols suggests a persistent warm,semi-humid,seasonal climate throughout most of the interval of deposition during the Wolfcampian,but with episodically increased aridity during formation of the more mature *** long-term trend of climate change is evident in the stratigraphic section examined for this study.

关键词： Sangre de Cristo Formation Wolfcampian Vertisol Argillisol Calcisol Protosol

End-Triassic nonmarine biotic events

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Journal of Palaeogeography 2015年第4期4卷 331-348页

作者： spencer g.Lucas Lawrence H.Tanner New Mexico Museum of Natural History Department of Biological Sciences Le Moyne College

The Late Triassic was a prolonged interval of elevated extinction rates and low origination rates that manifested themselves in a series of extinctions during Carnian, Norian and rhaetian time. Most of these extinctions took place in the marine realm, particularly affecting radiolarians, conodonts, bivalves, ammonoids and reef-building organisms. On land, the case for a Late Triassic mass extinction is much more tenuous and has largely focused on tetrapod vertebrates（amphibians and reptiles）, though some workers advocate a sudden endTriassic（TJB） extinction of land plants. Nevertheless, an extensive literature does not identify a major extinction of land plants at the TJB, and a comprehensive review of palynological records concluded that TJB vegetation changes were non-uniform（different changes in different places）, not synchronous and not indicative of a mass extinction of land plants. Claims of a substantial perturbation of plant ecology and diversity at the TJB in East greenland are indicative of a local change in the paleoflora largely driven by lithofacies changes resulting in changing taphonomic filters. Plant extinctions at the TJB were palaeogeographically localized events, not global in extent. With new and more detailed stratigraphic data, the perceived TJB tetrapod extinction is mostly an artifact of coarse temporal resolution, the compiled correlation effect. The amphibian, archosaur and synapsid extinctions of the Late Triassic are not concentrated at the TJB, but instead occur stepwise, beginning in the Norian and extending into the Hettangian. There was a disruption of the terrestrial ecosystem across the TJB, but it was more modest than generally claimed. The ecological severity of the end-Triassic nonmarine biotic events are relatively low on the global scale. Biotic turnover at the end of the Triassic was likely driven by the CAMP（Central Atlantic Magmatic Province） eruptions, which caused significant environmental perturbations（cooling, warming,

关键词： Triassic-Jurassic boundary mass extinction land plants East greenland tetrapods Newark Supergroup CAMP volcanism

Projective Hilbert modules and sequential approximations

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Science China Mathematics 2025年第1期 137-168页

作者： Lawrence g.Brown Huaxin Lin Department of Mathematics Purdue University Department of Mathematics East China Normal University Department of Mathematics University of Oregon Shanghai Institute for Mathematics and Interdisciplinary Sciences

We show that when A is a separable C*-algebra,every countably generated Hilbert A-module is projective（with bounded module maps as morphisms）.We also study the approximate extensions of bounded module *** the case where A is a σ-unital simple C*-algebra with strict comparison,and every strictly positive lower semicontinuous affine function on quasitraces can be realized as the rank of an element in the Cuntz semigroup,we show that the Cuntz semigroup is equivalent to unitarily equivalent classes of countably generated Hilbert A-modules if and only if A has stable rank one.

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