Audience-induced inhibition of overt practice during learning.

Three experiments with 204 undergraduates examined the hypothesis that an audience can inhibit overt practice and thereby impair learning of unfamiliar words and enhance learning of familiar words. This hypothesis was derived from an analysis of motoric and symbolic mediation during learning. In comparison with learning while alone, the results show that the audience inhibited overt practice of unfamiliar and familiar words and that reduced practice was detrimental to learning unfamiliar words. Inhibition of overt practice with an audience enhanced learning of familiar words in only 1 of the experiments. Instructions to practice overtly reduced the audience-inhibition effect in learning unfamiliar words. The studies are discussed in the context of drive-theory explanations for social facilitation effects in learning. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A Fast Hardware Approach for Approximate, Efficient Logarithm and Antilogarithm Computations

The realization of functions such as log() and antilog() in hardware is of considerable relevance, due to their importance in several computing applications. In this paper, we present an approach to compute log() and antilog() in hardware. Our approach is based on a table lookup, followed by an interpolation step. The interpolation step is implemented in combinational logic, in a field-programmable gate array (FPGA), resulting in an area-efficient, fast design. The novelty of our approach lies in the fact that we perform interpolation efficiently, without the need to perform multiplication or division, and our method performs both the log() and antilog() operation using the same hardware architecture. We compare our work with existing methods, and show that our approach results in significantly lower memory resource utilization, for the same approximation errors. Also our method scales very well with an increase in the required accuracy, compared to existing techniques.     

跳频与扩频：无线机器对机器接口

无线机器对机器接口代表了计算机发展的第三次浪潮.第一次浪潮是企业计算机、昂贵的主机以及只有大企业才有能力购买的超级计算机.这一阶段为上世纪的六十和七十年代.第二次计算机浪潮开始于1981年,当时IBM推出了个人计算机(PC).这一时期为上世纪的八十和九十年代.新世纪带来了第三次计算机浪潮.在此期间成本降低、新技术不断涌现,使计算机中采用嵌入式处理器及无线通信像烤箱一样普及.这些处理器独立工作时可提供特定的功能,但当它们在无人为干预时,自身间相互通信时作用更大.随着小型廉价计算机的发展,无线技术应运而生.无线移动电话技术的出现领导了这些进步技术.这些技术包括用于手机的无线网络和增长迅速的无线热点现象(图1).     

Convective Delivery of Electroactive Species to Annular Nanoband Electrodes Embedded in Nanocapillary‐Array Membranes

Significant technological drivers motivate interest in the use of reaction sites embedded within nanometer‐scale channels, and an important class of these structures is realized by an embedded annular nanoband electrode (EANE) in a cylindrical nanochannel. In this structure, the convective delivery of electroactive species to the nanoelectrode is tightly coupled to the electrochemical overpotential via electroosmotic flow. Simulation results indicate that EANE arrays significantly outperform comparable microband electrode/microchannel structures, producing higher conversion efficiencies at low Peclet number. The results of this in‐depth analysis are useful in assessing possible implementation of the EANE geometry for a wide range of electrochemical targets within microscale total analysis systems.     

In-situ measurement of ethanol tolerance in an operating fuel cell

Ethanol is seen as an attractive option as a fuel for direct ethanol fuel cells and as a source for on-demand production of hydrogen in portable applications. While the effect of ethanol on in-situ electrode behavior has been studied previously, these efforts have mostly been limited to qualitative analysis. In alkaline fuel cells, several cathode catalysts, including Pt, Cu triazole, and Ag can be used. Here, we apply a methodology using a microfluidic fuel cell to analyze in-situ the performance of these cathodes as well as Pt anodes in the presence of ethanol and acetic acid, a common side product from ethanol oxidation. For a given concentration of ethanol (or acetic acid), the best cathode catalyst can be determined and the kinetic losses due to the presence of ethanol (or acetic acid) can be quantified. These experiments also yield information about power density losses from the presence of contaminants such as ethanol or acetic acid in an alkaline fuel cell. The methodology demonstrated in these experiments will enable in-situ screening of new cathodes with respect to contaminant tolerance and determining optimal operational conditions for alkaline ethanol fuel cells.     

Unusual Temperature Dependence of Heterogeneous Nucleation of Water Vapor on Ag Particles

Copyright 2013 American Association for Aerosol Research     

Shadow series in the Munsell system

Using an inversion of the Munsell renotation, this article calculates that a colour's shadow series is approximately a straight line in the Munsell system. The line starts at the colour's Munsell specification and ends about one value step below N0, on the neutral axis. The colour's hue in shadow shifts slightly towards the yellow part of the spectrum. The calculations suggest that ideal black belongs at about N(?1) in the Munsell system, rather than at N0, if equality of perceptual steps is to be maintained. Similarly, ideal white should be slightly lighter than N10. © 2011 Wiley Periodicals, Inc. Col Res Appl, 2013