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Digital neuromorphic technology: current and future prospects

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National Science Review 2024年第5期11卷 10-11页

作者： steve Furber Department of Computer Science The University of Manchester

Neuromorphic technology has diversified considerably from its origins in the seminal work by Carver Mead and his group at Caltech in the 1980s [1]. That early work focussed on the analogy between the equations describing the flow of ions in biological neurons and the equations describing the flow of carriers in field-effect transistors operating in the subthreshold region.

关键词： technology current future digital neuromorphic prospects

Modern Black Sea oceanography applied to the end-Permian extinction event

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Journal of Palaeogeography 2015年第1期4卷 52-62页

作者： steve Kershaw Institute for the Environment Health and Societies Brunel UniversityKingston LaneUxbridge Middlesex UB8 3PH UK

The modern Black Sea has a mixed upper layer in the top 150-200 m of the water column, below which the water is anoxic, separated from the mixed layer by a redox boundary. There is limited vertical movement of water. Pyrite framboids form in the water column of the anoxic zone, then have been traditionally interpreted to sink immediately and accumulate in the sediments of the Black Sea. Thus the occurrence of framboids in sediments in the rock record is widely interpreted to indicate poorly oxygenated to anoxic conditions in ancient environments. However, in the Permian-Triassic boundary （PTB） microbialites of South China, which formed in shallow marine conditions in contact with the atmosphere, the published occurrence of framboids is inconsistent with abundant gastropod and ostracod shells in the microbialite. Furthermore, in the modern Black Sea, （a） framboids may be suspended, attached to organic matter in the water column, thus not settle to the sea floor immediately after formation; and （b） the redox zone is an unstable complex area subject to rapid vertical water movement including occasional upwelling. The model presented here supposes that upwelling through the redox zone can lead to upward transport of suspended pyrite framboids into the mixed layer. Advective circulation could then draw suspended framboids onto the shelf to be deposited in oxygenated sediments. In the Permian-Triassic transition, if framboids were upwelled from below the redox boundary and mixed with oxygenated waters, sediment deposited in these conditions could provide a mixed signal for potentially misleading interpretations of low oxygen conditions. However, stratigraphic sampling resolution of post-extinction microbialites is currently insufficient to demonstrate possible separation of framboid-bearing layers from those where framboids are absent. Profound differences between microbialite constructors and sequences between the western and eastern Tethys demonstrate barriers to migra

关键词： mass extinction Permian-Triassic boundary microbialite ostracods gastro-pods anoxia Black Sea

Improving reflectance estimation by BRDF-consistent region clustering

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Progress in Natural Science:Materials International 2006年第3期16卷 313-320页

作者： LIN steve Beijing 100080 China Visual Computing Group Microsoft Research Asia

Previous studies in reflectance estimation generally require prior segmentation of an image into regions of uniform reflectance. Due to the measurement noise and limited sampling of the BRDF (bi-directional reflectance function) directions, such estimated results of reflectance are not accurate. In this paper, we propose a novel method for reducing uncertainty in reflectance estimates by merging image regions which have consistent reflectance observations. Each image region acts as a reflectance subspace, so merging of the image regions can result in subspace reduction. We propose a Bayesian segmentation framework to decrease the reflectance uncertainty by using novel merging criteria. Finally, a maximum likelihood reflectance estimation is made for each resulting image region. Experimental results verify the feasibility and superiority of this reflectance-oriented region merging method.

关键词： texture shading grouping and segmentation reflectance estimation BRDF uncertainty.

Quantitative Absolute Continuity of Harmonic Measure and the Dirichlet Problem: A Survey of Recent Progress

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Acta Mathematica Sinica,English Series 2019年第6期35卷 1011-1026页

作者： steve HOFMANN Department of Mathematics University of Missouri

It is a well-known folklore result that quantitative, scale invariant absolute continuity(more precisely, the weak-A∞ property) of harmonic measure with respect to surface measure, on the boundary of an open set Ω ? R^(n+1) with Ahlfors–David regular boundary, is equivalent to the solvability of the Dirichlet problem in Ω, with data in L^p (?Ω) for some p < ∞. Drawing an analogy to the famous Wiener criterion, which characterizes the domains in which the classical Dirichlet problem, with continuous boundary data, can be solved, one may seek to characterize the open sets for which L^psolvability holds, thus allowing for singular boundary *** has been known for some time that absolute continuity of harmonic measure is closely tied to rectifiability properties of ?Ω, but also that rectifiability alone is not sufficient to guarantee absolute continuity. In this note, we survey recent progress in this area, culminating in a geometric characterization of the weak-A∞ property, and hence of solvability of the L^p Dirichlet problem for some finite p. This characterization, obtained under rather optimal background hypotheses, follows from a combination of the present author's joint work with Martell, and the work of Azzam, Mourgoglou and Tolsa.

关键词： Harmonic measure Poisson kernel uniform rectifiability weak local John condition big pieces of chord-arc domains Carleson measures

Underground mine stream crossing assessment:A multi-disciplinary approach

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International Journal of Mining Science and Technology 2021年第1期31卷 59-65页

作者： Kevin Andrews steve Keim Marshall Miller&Associates BluefieldVA 24605USA

Underground mine designs typically try to avoid extraction beneath streams and rivers of any significant size,especially when the overburden rock thickness between the stream bed and the mine is *** issues with mining beneath streams include excessive groundwater inflow to the mine,weak ground(roof,floor,and pillar)conditions,horizontal stress effects,as well as stream loss and other potential adverse environmental ***,there are times when crossing beneath a stream or river is necessary to move into a new area of mineral reserve without creating additional mine access points from the ground ***,stream crossings are completed without thorough assessment,potentially resulting in increased costs,decreased safety,and,in some cases,failure to advance the *** of the most favorable location(s)to cross the stream must account for numerous factors and the associated assessment often requires a multi-disciplinary *** crossing investigations often require geological,hydrogeological,geotechnical,and geophysical *** of stream crossing investigations include desktop evaluation of maps and aerial photography,stream bed observations,drilling,detailed rock core logging,downhole geophysical surveying,hydraulic conductivity testing(packer testing),geotechnical laboratory testing,assessment,and *** deliverables from a stream crossing assessment typically include geological,geotechnical,and hydrogeological characterization of potential stream crossing locations,classification of favorable and unfavorable crossing locations,recommendations for entry design and pillar sizing,and recommendations for if,and how,to conduct pre-grouting *** of technical aspects of data collection and assessment are provided based on decades of industry experience conducting stream crossing assessments in various underground mining scenarios.

关键词： Underground mining Geotechnical Stream-crossing Hydrogeology Characterization

Green spermatozoa illuminate a 30-year-old model： sperm-egg adhesion involves intra-acrosomal proteins

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Asian Journal of Andrology 2011年第5期13卷 665-666页

作者： steve Tardif Reproductive and Developmental Biology Group Centrefor Oncology and Molecular Medicine Division ofMedical Sciences Ninewells Hospital University ofDundee Dundee Scotland DD1 9SY UK

Fertilisation in mammals involves many synchronized steps including spermegg adhesion. Prior to sperm-oolemma fusion, spermatozoa need to undergo the acrosome reaction （AR） or exocytosis. The universal belief, for many years, has been that the AR was initiated upon binding to the zona pellucida （ZP）. As such acrosomal proteins were not thought to be involved in the primary contact with the ZP. These proteins were only suggested to be biologically relevant once the sperm were attached to the ZP and during subsequent events. However,

关键词： Green reexamination

A Subjective Risk Analysis Approach of Container Supply Chains

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International Journal of Automation and computing 2005年第1期2卷 85-92页

作者： steve Bonsall School of Engineering Liverpool John Moores University Liverpool L3 3AF UK

After the 9/11 terrorism attacks, the lock-out of the American West Ports in 2002 and the breakout of SARS disease in 2003 have further focused mind of both the public and industrialists to take effective and timely measures for assessing and controlling the risks related to container supply chains (CSCs). However, due to the complexity of the risks in the chains, conventional quantitative risk assessment (QRA) methods may not be capable of providing sufficient safety management information, as achieving such a functionality requires enabling the possibility of conducting risk analysis in view of the challenges and uncertainties posed by the unavailability and incompleteness of historical failure data. Combing the fuzzy set theory (FST) and an evidential reasoning (ER) approach, the paper presents a subjective method to deal with the vulnerability-based risks, which are more ubiquitous and uncertain than the traditional hazard-based ones in the chains.

关键词： Container supply chains risk assessment evidential reasoning fuzzy sets vulnerability

Pulse gas alignment and AFM manipulation of single-wall carbon nanotube

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Chinese Science Bulletin 2008年第22期53卷 3590-3596页

作者： TUNG steve State Key Laboratory.of Robotics Shenyang Institute of Automation Chinese Academy of Sciences

In the fabrication process of nanoelectronic device arrays based on single-wall carbon nanotube (SWCNT), oriented alignment of SWCNTs and property modification of metallic SWCNTs in the array are the key problems to be solved. Pulse gas alignment with substrate downward tilt is proposed to realize the controllable alignment of SWCNTs. Experimental results demonstrate that 84% SWCNTs are aligned in -15°―15° angular to the pulse gas direction. A modified nanomanipulation technology based on atomic force microscope (AFM) is utilized to perform various kinds of SWCNT manipulation, such as SWCNT separation from the "Y" CNT, catalyst removal from the SWCNT end, continual nano buckles fabrication on SWCNT and even stretching to break, which provides a feasible way to modify the size, shape and the electrical property of SWCNTs.

关键词： SWCNT 碳纳米管显微镜 AFM

Nickel-catalyzed enantioselective reductive amination of benzylic ketones in alcohols

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Science China Chemistry 2024年第8期67卷 2566-2570页

作者： Xiuhua Wang Jianrong steve Zhou State Key Laboratory of Chemical Oncogenomics School of Chemical Biology and BiotechnologyPeking University Shenzhen Graduate SchoolShenzhen 518055China

Asymmetric reductive amination directly converts ketones and amines to alkylamines, which are important motifs in *** report that cationic nickel complexes of chiral diphosphines promote enantioselective reductive amination of benzylic ketones with both arylamines and benzhydrazide. Isopropanol was used as a safe and cheap source of hydrogen instead of formic acid. The reaction can be readily applied to a concise synthesis of diarylethylamines, a class of neuroactive substances.

关键词： transfer hydrogenation nickel catalysis chiral alkylamine reductive amination synthetic method