检索结果-南通市图书馆

Exact Computation of the Topology and Geometric Invariants of the Voronoi diagram of Spheres in 3d

在线全文

学校读者我要写书评

暂无评论

Journal of Computer Science & Technology 2013年第2期28卷 255-266页

作者： Franois anton darka Mioc Marcelo Santos Research division of Geodesy National Space Institute Technical University of Denmark department of Geodesy and Geomatics Engineering University of New Brunswick

In this paper, we are addressing the exact the Voronoi diagram of spheres using Wu＇s algorithm. computation of the delaunay graph （or quasi-triangulation） and Our main contributions are first a methodology for automated derivation of invariants of the delaunay empty circumsphere predicate for spheres and the Voronoi vertex of four spheres, then the application of this methodology to get all geometrical invariants that intervene in this problem and the exact computation of the delaunay graph and the Voronoi diagram of spheres. To the best of our knowledge, there does not exist a comprehensive treatment of the exact computation with geometrical invariants of the delaunay graph and the Voronoi diagram of spheres. Starting from the system of equations defining the zero-dimensional algebraic set of the problem, we are applying Wu＇s algorithm to transform the initial system into an equivalent Wu characteristic （triangular） set. In the corresponding system of algebraic equations, in each polynomial （except the first one）, the variable with higher order from the preceding polynomial has been eliminated （by pseudo-remainder computations） and the last polynomial we obtain is a polynomial of a single variable. By regrouping all the formal coefficients for each monomial in each polynomial, we get polynomials that are invariants for the given problem. We rewrite the original system by replacing the invariant polynomials by new formal coefficients. We repeat the process until all the algebraic relationships （syzygies） between the invariants have been found by applying Wu＇s algorithm on the invariants. Finally, we present an incremental algorithm for the construction of Voronoi diagrams and delaunay graphs of spheres in 3d and its application to Geodesy.

关键词： Voronoi diagram of spheres delaunay graph of spheres Wu's method invariant characteristic set

Change in carbonate budget and composition during subduction below metal saturation boundary

在线全文

学校读者我要写书评

暂无评论

Geoscience Frontiers 2023年第1期14卷 79-100页

作者： anton Shatskiy anton V.Arefiev Konstantin d.Litasov Vernadsky Institute of Geochemistry and Analytical Chemistry Russian Academy of SciencesMoscow 119991Russia Vereshchagin Institute for High Pressure Physics Russian Academy of SciencesTroitskMoscow 108840Russia

It is generally accepted that carbonates can be subducted to the mantle depths,where they are reduced with iron metal to produce a *** this work,we found that this is not always the *** mantle carbonates from inclusions in diamonds show a wide range of cation compositions(Mg,Fe,Ca,Na,and K).Here we studied the reaction kinetics of these carbonates with iron metal at 6-6.5 GPa and 1000-1500℃.We found that the reduction of carbonate with Fe produces C-bearing species(Fe,Fe-C melt,Fe_(3)C,F e_(7)C_(3),C)and wüistite containing Na_(2)O,CaO,and *** reaction rate constants(k=△x^(2)/2t)are log-linear relative to 1/T and their temperature dependences are determined to be k_(MgcO_(3))(m^(2)/s)=4.37×10^(-3)exp[-251(kJ/mol)/RT]k_(caMg(CO_(3))2)(m^(2)/s)=1.48×10^(-3)exp[-264(kJ/mol)/RT]k_(cacO_(3))(m^(2)/s)=3.06×10^(-5)exp[-245(kJ/mol)/RT]and k_(Na_(2)cO_(3))(m^(2)/s)=1.88×10^(-10)exp[-155(kJ/mol)/RT].According to obtained results at least,45-70 vol%of carbonates preserve during subduction down to the 660-km discontinuity if no melting *** slab stagnation and warming,subsequent carbonate melting,and infiltration into the mantle saturated with iron metal are accompanied by a reduction of carbonate melt with *** established sequence of reactivity of carbonates:FeCO_(3)≥MgCO_(3)>CaMg(CO_(3))2>CaCO_(3)>>Na_(2)CO_(3),where K_(2)CO_(3)does not react at all with iron metal,implies that during reduction carbonate melt with Fe evolves toward *** above conclusions are consistent with the findings of carbonates in inclusions in diamonds from the lower mantle and high concentrations of alkalis,particularly K,in mantle carbonatite melts entrapped by diamonds from kimberlites and placers worldwide.

关键词： Carbonate Reduction of carbonate with Fe Reaction kinetics Carbonatite melt High-pressure experiment Earth's mantle

Biochemical dissection of STAT3 signaling in amyotrophic lateral sclerosis

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Neural Regeneration Research 2025年第11期20卷 3229-3230页

作者： Savina Apolloni Nadia d’Ambrosi department of Biology University of Rome Tor VergataRomeItaly

Amyotrophic lateral sclerosis(ALS)is a progressive neurodegenerative disease characterized by the loss of upper and lower motor neurons,clinically marked by muscle atrophy and *** the clinical course is highly variable,the average time from the onset of symptoms to the need for respiratory support or death is 3-5 *** is the most prevalent motor neuron disease in adults,occurring at a rate of 2 per 100,000 individuals and affecting 5.4 per 100,000 individuals overall.

关键词： STAT3 dissection sclerosis

Anti-amyloid antibodies in Alzheimer’s disease: what did clinical trials teach us?

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2025年第4期20卷 1092-1093页

作者： danko Jeremic Lydia Jiménez-díaz Juan d.Navarro-López NeuroPhysiology&Behavior Lab University of Castilla-La ManchaBiomedical Research Center(CRIB)School of Medicine of Ciudad RealCiudad RealSpain

Although many causes of Alzheimer’s disease(Ad)may exist,both the original amyloid cascade and tau hypotheses posit that abnormal misfolding and accumulation of amyloid-β(Aβ)and tau protein is the central event causing the ***,that conclusion could be only partly true,and there is conflicting evidence about the role of both proteins in Ad,being able to precede and influence one *** researchers argue that these proteins are mere executors rather than primary causes of ***,there have been continuing refinements of both hypotheses,with alternative explanations proposed.Aβand tau proteins may be independently involved in specific neurotoxic pathways;yet there may be other crucial processes going on in early ***,accumulating evidence suggests that Aβand tau act synergistically,rather than additively in disease onset(Jeremic et al.,2021,2023a).

关键词： amyloid Alzheimer additive

Remaking a connection:molecular players involved in post-injury synapse formation

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2025年第6期20卷 1719-1720页

作者： diogo Tomé Ramiro d.Almeida iBiMEd-Institute of Biomedicine Department of Medical SciencesUniversity of AveiroAveiroPortugal CNC-Center for Neuroscience and Cell Biology University of CoimbraCoimbraPortugal

Functional recovery from central nervous system(CNS)trauma depends not only on axon regeneration or compensatory sprouting of uninjured fibers but also on the ability of newly grown axons to establish functional synapses with appropriate *** several studies have successfully promoted long-distance axonal regeneration in distinct CNS injury models,none of them have resulted in a viable therapeutic approach for patient recovery.A possible reason may be the lack of new synaptogenesis for reestablishing the circuitry lost after ***,we discuss how our understanding of the mechanisms that instruct synapse formation in the injured nervous system may contribute to the design of new strategies to promote functional restoration in traumatic CNS disorders.

关键词： viable injury instru

Genetic link between saline and carbonatitic mantle fluids:The system NaCl-CaCO_(3)-MgCO_(3)±H_(2)O±Fe^(0) at 6 GPa

在线全文

学校读者我要写书评

暂无评论

Geoscience Frontiers 2022年第6期13卷 59-74页

作者： anton Shatskiy Ivan V.Podborodnikov anton V.Arefiev Altyna Bekhtenova Konstantin d.Litasov Vernadsky Institute of Geochemistry and Analytical Chemistry of the Russian Academy of Science Moscow 119991Russia Vereshchagin Institute for High Pressure Physics of the Russian Academy of Science TroitskMoscow108840Russia

Melt inclusions in kimberlitic minerals and diamonds indicate that chlorides are important constituents of mantle carbonatite ***,alkaline chlorides are important constituents of saline high-density fluids(HdFs)found in diamonds from kimberlites and placers around the *** compositional variations suggest that saline and carbonatitic HdFs could be genetically ***,the essence of this link remains unclear owing to the lack of data on phase relations in the chloridecarbonate systems under *** we studied subsolidus and melting phase relations in the system NaCl–CaCO_(3)–MgCO_(3)at 6 GPa and 1000–1600℃using a Kawai-type multianvil *** found that at 1000℃,subsolidus assemblage consists of halite,magnesite,and *** higher temperatures,the stabilization of dolomite splits the subsolidus area into two partial ternary fields:halite+magnesite+dolomite and halite+dolomite+*** minimum on the liquidus surface corresponds to the halite-dolomite-aragonite ternary eutectic,situated at 1100℃.The eutectic melt has Ca#89 and contains 30 wt.%Na Cl(26 mol%2NaCl).The system has two ternary peritectics:halite+dolomite=magnesite+liquid located near the ternary eutectic and magnesite+dolomite=Mg-dolomite+liquid situated between 1300 and 1400℃.Although under dry conditions incipient melting yields carbonatedominated melt,the addition of water facilitates the fusion of Na Cl and expands the liquid field to Na Cl-rich compositions with up to 70 wt.%Na *** obtained results favor the idea that hydrous saline melts/fluids(brines)found as inclusions in diamonds could be a lower temperature derivative of mantle carbonatite melts and disagree with the hypothesis on chloride melt generation owing to the chloridecarbonate liquid immiscibility since no such immiscibility was *** also studied the interaction of the NaCl–CaCO_(3)–MgCO_(3)system with iron metal and found that carbonate reduction produces Cbearing species(Fe^(0)

关键词： Chloride Carbonate Halite Melting T-X diagram Earth’s mantle

A methodological framework for analyzing PPGIS data collected in 3d

在线全文

学校读者我要写书评

暂无评论

International Journal of digital Earth 2023年第1期16卷 3435-3455页

作者： Kamyar Hasanzadeh Nora Fagerholm Hans Skov-Petersen anton Stahl Olafsson department of Geography and Geology University of TurkuTurkuFinland department of Geosciences and Natural Resource Management University of CopenhagenCopenhagenDenmark

Public participation geographic information system(PPGIS)is a facilitated Volunteered Geographic Information approach and data collection method that aims to capture the spatial experiences of *** we experience the space around us three-dimensionally,altitude,as the third dimension,has been often absent from PPGis research and *** is largely because of the complexity of implementing surveys in 3d but can also be attributed to a lack of analytical preparedness for using such *** study complements 3d PPGIS data collected from a pilot study of the Aninkainen block in Turku,Finland with synthetic,*** manufactured,data to propose an analytical framework for the study of 3d PPGIS *** analytical framework divides methods based on the geographical scale into two groups:micro-and macro-scale *** this framework,we propose the use of geospatial metrics to analyze 3d PPGIS *** argue that while this multidisciplinary area of research is in its infancy,use of intuitive 3d adapted geometric and landscape metrics can help overcome some of complexities associated with use of this emerging participatory *** conclude by outlining the limitations and envisioning areas for future research.

关键词： 3d GIS landscape metrics PPGIS

Remote sensing ***-based monitoring of agricultural terrace degradation

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Soil and Water Conservation Research 2021年第1期9卷 1-10页

作者： anton Pijl Edoardo Quarella Teun A.Vogel Vincenzo d'Agostino Paolo Tarolli dept.of Land EnvironmentAgriculture and ForestryUniversity of PadovaVialedell'Università1635020LegnaroPDItaly Soil Physics and Land Management Group Wageningen UniversityDroevendaalsesteeg 46708PBWageningenthe Netherlands

The degradation of agricultural terraces is considered a major challenge to soil and water conservation in steep-slope *** terracing is a widespread conservation practice,its sustainability is threatened by adverse climatic and man-made *** studies have shown the impact of terrace designs on the formation of runoff pathways,causing degradation processes on terrace platforms(*** erosion)and walls(***,landslides,collapse).This study evaluates a remote sensing versus a field-based approach to monitor hydrological processes responsible for terrace degradation,as tested in a north-Italian *** field-based approach was based on spatially measured Soil Moisture Content(SMC)using a Time domain Reflectometry(TdR)instrument,which clearly revealed saturation hotspots around two damaged terraces in the study ***,these zones showed a particular cross-sectional SMC profile,with the highest saturation close to the terrace platform *** remote sensing approach was based on aerial imagery acquired by an Unmanned Aerial Vehicle(UAV)and photogrammetric reconstruction of the vineyard geomorphology,allowing terrain-based analysis and physical erosion *** this approach,simulations indicated that terrace damages could be partly explained by the formation of preferential runoff pathways caused by the terrace *** parallel methodology allowed a comparison of the merits and limitations of either approach,as done in light of published *** occurrence of two SMC hotspots at terrace edges(and their non-typical cross-sectional profiles)could be better understood from simulated surface flow *** the causal relationship between heterogeneous soil saturation and terrace instability has been previously reported in literature,the novelty of the presented study is the use of topsoil SMC as an indicator of potential damages,favouring the scalability compared to fixed,local and often intrusive terrace sub-sur

关键词： Agricultural terraces Remote sensing UAV Soil moisture Land degradation

Simulation of Liquid Metal droplets from Field Emission

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Communications in Computational Physics 2007年第4期2卷 640-661页

作者： anton VanderWyst Andrew Christlieb Mark Sussman Iain d.Boyd Raytheon Missile Systems 1151 E.Hermans RoadP.O.Box 11337TucsonAZ 85734USA department of Mathematics Michigan State UniversityEast LansingMI 48824USA department of Mathematics Florida State UniversityTallahasseeFL 32306USA department of Aerospace Engineering University of MichiganAnn ArborMI 48109USA.

Liquid metal droplets are accelerated by electrostatic forces in a process known as field *** this study,we simulate the emission of charged indium droplets on a needle in 2d cylindrical *** boundary element method is used to rapidly and accurately calculate the electric field on the fluid surface,which is then advected forward in time using level *** is the first time these methods have been combined,and this combination addresses difficult detachable surface tracking issues successfully.A histogram of droplet charge-to-mass ratio is generated in which it is predicted that smaller satellite droplets are more densely *** addition,our model is compared with independent pre-and post-snap off data and produces good agreement with the result.

关键词： Field emission electric propulsion modeling level set boundary element method