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P Nádvornik P Krupa J Chrastina V Smrcka Z Novák E Zborilová 《Canadian Metallurgical Quarterly》1997,139(4):359-360
The authors propose a new method for performing stereotactic callosotomy, which they have named circular callosotomy. The operating device is the original Riechert-Mundinger's string electrode, which can be protruded through a side window and by rotating the probe it is possible to cut the commisural pathways to the extent required. The anatomical results of the operation can be checked using MRI scanning. 相似文献
3.
Oded Goldreich 《Distributed Computing》2003,16(2-3):177-199
We survey the paradigms, approaches and techniques used to conceptualize, define and provide solutions to natural cryptographic problems. We start by presenting some of the central tools (e.g., computational difficulty, pseudorandomness, and zero-knowledge proofs), and next turn to the treatment of encryption and signature schemes. We conclude with an extensive treatment of secure cryptographic protocols both when executed in a stand-alone manner and when many sessions of various protocols are concurrently executed and controlled by an adversary. The survey is intended for researchers in distributed computing, and assumes no prior familiarity with cryptography.Received: June 2001, Accepted: July 2002, 相似文献
4.
P. Podhájecký B. Klápště P. Novák J. Mrha R. Moshtev V. Manev A. Nassalevska 《Journal of power sources》1985,14(4):269-275
A dozen CuO samples prepared under various conditions and from different starting materials were evaluated as cathode materials for a primary Li/CuO cell. The “thin electrode” method was used for rapid evaluation of the samples. Both coulombic efficiency and discharge voltage depend considerably on the method of synthesis. No correlation was found between the specific surface area and the resistivity of the samples on the one hand and the cathode performance on the other. Best results were obtained from CuO prepared by the oxidation of Cu2O under controlled temperature and time of oxidation. 相似文献
5.
We say that a distribution over {0,1}n is (ε,k)-wise independent if its restriction to every k coordinates results in a distribution that is ε-close to the uniform distribution. A natural question regarding (ε,k)-wise independent distributions is how close they are to some k-wise independent distribution. We show that there exist (ε,k)-wise independent distributions whose statistical distance is at least nO(k)·ε from any k-wise independent distribution. In addition, we show that for any (ε,k)-wise independent distribution there exists some k-wise independent distribution, whose statistical distance is nO(k)·ε. 相似文献
6.
Anna Sztaniszlav Magdolna Balla Maria Farkas-Jahnke Csaba Novák 《Journal of Materials Science》1990,25(5):2353-2358
The kinetics of solid-state reactions of powdered reactants were investigated by X-ray and by differential thermogravimetry in a magnetic field. Measurements revealed mutual diffusion of the Fe3+ and In3+ ions in the Fe2O3-In2O3 system heat treated for 3 h at 700 to 1400° C. Diffusion of indium into the Fe2O3 lattice caused a shift of the Curie temperature of the antiferromagnetic iron oxide towards lower temperatures. Only Caln2O4 was found between CaCO3 and In2O3 up to 1400° C. Also, in the Fe2O3-CaCO3-In2O3in system, the reaction started with the mutual diffusion of iron and indium and the forming of CaFe2O4. End-products were the magnetic -Ca4Fe14O25 and CaFe4O7, and the non-magnetic CaFe5O7, depending on the In3+ concentration. Indium stabilized the magnetic calcium-iron oxide structures, shifting their Curie temperatures towards lower values. 相似文献
7.
Carsten Dachsbacher Jaroslav Křivánek Miloš Hašan Adam Arbree Bruce Walter Jan Novák 《Computer Graphics Forum》2014,33(1):88-104
Recent years have seen increasing attention and significant progress in many‐light rendering, a class of methods for efficient computation of global illumination. The many‐light formulation offers a unified mathematical framework for the problem reducing the full lighting transport simulation to the calculation of the direct illumination from many virtual light sources. These methods are unrivaled in their scalability: they are able to produce plausible images in a fraction of a second but also converge to the full solution over time. In this state‐of‐the‐art report, we give an easy‐to‐follow, introductory tutorial of the many‐light theory; provide a comprehensive, unified survey of the topic with a comparison of the main algorithms; discuss limitations regarding materials and light transport phenomena and present a vision to motivate and guide future research. We will cover both the fundamental concepts as well as improvements, extensions and applications of many‐light rendering. 相似文献
8.
Short syntheses of (Z)-7-dodecen-1-yl acetate, (Z)-7-tetradecen-1-yl acetate, (Z)-9-dodecen-1-yl acetate, and (Z)-9-tetradecen-1-yl acetate from 7-hydroxyheptanal and 9-oxononanoic acid precursors obtained by oxidative cleavage of easily available aleuritic acid are reported. The key step in these syntheses is a stereoselective Wittig reaction between aldehyde and alkyl-phosphonium salt. Wittig-Horner type reaction of 7-hydroxyheptanal and diethyl cyanomethylphosphonate gave the ,-unsaturated nitrile derivative which after protection of the hydroxyl group was reduced to the corresponding aldehyde. Wittig reaction of the latter, followed by acetylation, completed the synthesis of (E,Z)-7,9-dodecadien-1-yl acetate, the sex pheromone of the European grapevine mothLobesia botrana Schiff. 相似文献
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We address concerns about the sustainability of the open source content model by examining the effect of external appropriation, whereby the product of open source contributors’ efforts is monetized by a party that did not contribute to the project, on intended effort withdrawal (reduction in contribution level). We examine both the personality of contributors and their contextual motivations to contribute, using a scenario-based survey of Wikipedia contributors. The findings suggest that perceived justice of the open source license terms, and intrinsic motivations are both negatively related with effort withdrawal intentions. Moreover, we find that the effect of the fairness personality trait on effort withdrawal is stronger for individuals who are low in perceived justice and weaker for individuals high in justice. The findings of factors predicting effort withdrawal contribute to the open source literature, which tends to focus on contribution and motivations, but not on what impacts changes in individual contribution levels. 相似文献