High-pressure electrical resistivity behaviour of nanocrystalline perovskite (La,Sr)(Mn,Fe)O3

We report here the electrical resistivity of nanocrystalline perovskite-structured La–Sr manganites as a function of pressures up to 8?GPa, at room temperature. The nanocrystalline perovskite manganites were prepared by the sol–gel technique and found to have crystallite sizes of 12–18?nm. The pressure dependence of the electrical resistivity shows a first-order phase transition at 0.66(2)?GPa and a subtle phase transition between 3.5 and 3.8?GPa. The first-order transition at 0.66?GPa can be related to the transition from localized-electron to band magnetism.     

On the Escaig obstacle hypothesis for cross-slip in face-centered-cubic materials

There is a significant body of literature wherein a linear approximation of Escaig's model is used to justify the large experimentally measured activation-volumes for cross-slip in face-centered-cubic copper. Here, by examining the error between the linear approximation and the original theory, we show that this explanation is not satisfactory. The calculated value for activation volume in copper, using Escaig's original equations, yields ～60b ³ (b?=?Burgers vector) while the linear approximation yields 200b ³, the latter result fortuitously matching the experimental values.     

The Underrepresentation of Women in Prestigious Ethics Journals

The main goal of this study is to determine whether women are underrepresented in prestigious ethics journals relative to their representation in the field of ethics. Our study proceeds in three steps. Step one: we estimate the percentage of women who specialize in ethics. Step two: we estimate the percentage of articles in prestigious ethics journals that are authored by women. Step three: we examine whether there is any difference between the percentage of women who specialize in ethics and the percentage of articles in prestigious ethics journals that are authored by women. We conclude that women are underrepresented in prestigious ethics journals relative to their representation in the field of ethics.     

Making Choices: Ethical Decisions in a Global Context

The changing milieu of research—increasingly global, interdisciplinary and collaborative—prompts greater emphasis on cultural context and upon partnership with international scholars and diverse community groups. Ethics training, however, tends to ignore the cross-cultural challenges of making ethical choices. This paper confronts those challenges by presenting a new curricular model developed by an international team. It examines ethics across a very broad range of situations, using case studies and employing the perspectives of social science, humanities and the sciences. The course has been developed and taught in a highly collaborative way, involving researchers and students at Zhejiang University, the Indian Institute of Technology, Bombay and Brown University. The article presents the curricular modules of the course, learning outcomes, an assessment framework developed for the project, and a discussion of evaluation findings.     

Asparagus recemosus enhances memory and protects against amnesia in rodent models

Asparagus Racemosus (AR) is an Ayurvedic rasayana possessing multiple neuropharmacological activities. The adpatogenic and antidepressant activity of AR is well documented. The present study was undertaken to assess nootropic and anti-amnesic activities of MAR in rats. The Morris water maze (MWM) and elevated plus maze (EPM) models were employed to evaluate learning and memory activity. Subsequently, the anti-amnestic activity was evaluated in scopolamine and sodium nitrite (NaNO₂)-induced amnestic models in rats. Rats pre-treated with MAR (50, 100 and 200 mg/kg, p.o) for 7 days showed significant decrease in escape latency in the MWM test indicating nootropic activity. MAR also significantly reversed scopolamine and sodium nitrite-induced increase in transfer latency on EPM indicating anti-amnesic activity. Further, MAR dose-dependently inhibited acetylcholinesterase enzyme in specific brain regions (prefrontal cortex, hippocampus and hypothalamus). Thus, MAR showed nootropic and anti-amnesic activities in the models tested and these effects may probably be mediated through augmentation of cholinergic system due to its anti-cholinesterase activity.     

Pressure dependence of the electrical resistivity of natural cassiterite SnO2 and of undoped and Co-doped nanocrystalline SnO2

The pressure dependence of the electrical resistivity of three different samples of cassiterite, namely natural cassiterite SnO₂, synthetic nanocrystalline SnO₂ (with crystallite size 46?nm) and nanocrystalline Co-doped SnO₂ (with crystallite size 32?nm), has been measured up to 7?GPa at room temperature. The resistivity of natural cassiterite SnO₂ decreases from 2.5?×?10⁴?Ωm at normal pressure and temperature to 1.7?×?10⁴?Ωm at 7.0?GPa. The nanocrystalline SnO₂ has a high resistivity 6.0?×?10⁵?Ωm at normal pressure and temperature and decreases with pressure reaching a value of 2.98?×?10⁵?Ωm at 7?GPa. The activation energy of the electrical conduction of the studied samples were found to be 0.32?eV for the natural SnO₂, 0.40?eV for the nanocrystalline SnO₂ sample and 0.28?eV for the nanocrystalline Co-doped SnO₂. Measurements of the pressure dependence of the electrical resistivity of the Co-doped SnO₂ showed a decrease from 3.60?×?10⁵ to 5.4?×?10⁴?Ωm at 7.0?GPa. We did not observe any pressure-induced phase transition in SnO₂ up to 7?GPa. This study of the high-pressure phase stability of cassiterite corroborates the experimental findings of SnO₂ nanoinclusions in diamonds.     

On the intrinsic and extrinsic motivation of free/libre/open source (FLOSS) developers

Motivation in the context of open source software may be seen as fundamentally different due to the presence of unpaid programmers, implicit rather than explicit forms of control and a different methodology for software development. Since software development is a creative task, the motivation of open source programmers can be compared to individuals in creative industries (Caves 2002). This paper summarizes the important trends in the research on motivation in open source and identifies variables that should be included in future research. Specifically, the current literature favors a taxonomy that considers two components of motivation—intrinsic (e.g., fun, flow, learning, community) and extrinsic (e.g., financial rewards, improving future job prospects, signaling quality). I make a case for incorporating both elements in developing an integrative theory about developer motivation. Three elements are identified as being unique to FLOSS development-diversity of project structures, co-existence of companies and communities and co-existence of creative and commercial elements. The important empirical evidence on FLOSS developer motivation is presented and analyzed. Four factors are identified as important mitigating and moderating factors in the conversation surrounding developer motivation- financial incentives, nature of task, group size and group structure. The role of these factors on developer motivation is discussed. He is passionately interested in all aspects of open source software development and has written extensively on the topic. He is also the author of two books on E-Commerce.     

Enumeration of paths in digraphs

The solution of the problem of enumeration of then-paths in a digraph has so far been attempted through an indirect approach of enumerating the redundant chains. The approach has yielded an algorithm for determination of the general formula for the matrix of redundantn-chains and also a partial recurrence formula for the same. This paper presents a direct approach to the problem. It gives a recurrence relation expressing the matrix ofn-paths of a digraph in terms of the matrices of (n – 1)-paths of its first-order subgraphs. The result is exploited to give an algorithm for computing the matrix ofn-paths. The algorithm is illustrated with a 6 × 6 matrix.The writer wishes to express his indebtedness to Dr. A. K. Gayen of Indian Institute of Technology, Kharagpur, for constant guidance and encouragement. Thanks are also due to Dr. S. N. N. Pandit of the Indian Institute of Technology, Kharagpur, and Shri M. T. Subrahmanya of Indian Statistical Institute, Calcutta, for helpful suggestions.