A Social Network Perspective on the Success of Open Source Software: The Case of R Packages

In this paper, we seek to identify the factors that influence the impact of open source software (OSS) on users community through the analysis of the evolution of the OSS network. Based on longitudinal data collected from the comprehensive R archive network (CRAN), we empirically examine how the network of R packages evolves over time and exert its influence on the scientific community. We find that critical network features derived from CRAN, such as page-rank, closeness, and betweenness centralities, play a significant role in determining the impact of each package on the research and publication activities in the scientific community. Furthermore, the performance of R packages can be explained as a flow of information from the core to the periphery that exhibits strong spillover effects

Method Effects in IS Survey Research: An Assessment and Recommendations

Issues involving method effects are routinely taught to PhD students in Information Systems (IS). Unfortunately, the results of an assessment of a population of 128 survey-based studies published in three top IS journals over a six-year period (1999-2005) reveal that relatively little attention is being paid to method bias and that the threat of serious method bias is great in many of the published studies. For instance, even the best-understood variety of method bias--common source bias--is found to have gone unnoted in over one-third of the papers that used a single respondent for all construct measures for reasons other than necessity. This study was motivated by studies in other areas of the social sciences which have resulted in calls for areas such as IS to conduct empirical assessments of the frequency of the various forms of method bias. Here, the myriad sources of method bias are reviewed and methods for minimizing or eliminating method effects, both in the design of a study and in the subsequent analysis of the data, are discussed. Data on the frequency of appearance of a wide variety of potential sources of method bias are provided and conclusions are drawn. A series of recommendations is made concerning creating greater awareness of method bias on the part of the IS research community and greater use of method bias criteria in the screening reviews of papers that are done by IS journals

The Faint End Slopes Of Galaxy Luminosity Functions In The COSMOS 2-Square Degree Field

We examine the faint-end slope of the rest-frame V-band luminosity function (LF), with respect to galaxy spectral type, of field galaxies with redshift z<0.5, using a sample of 80,820 galaxies with photometric redshifts in the Cosmic Evolution Survey (COSMOS) field. For all galaxy spectral types combined, the LF slope, alpha, ranges from -1.24 to -1.12, from the lowest redshift bin to the highest. In the lowest redshift bin (0.02<z<0.1), where the magnitude limit is M(V) ~ -13, the slope ranges from ~ -1.1 for galaxies with early-type spectral energy distributions (SEDs), to ~ -1.9 for galaxies with low-extinction starburst SEDs. In each galaxy SED category (Ell, Sbc, Scd/Irr, and starburst), the faint-end slopes grow shallower with increasing redshift; in the highest redshift bin (0.4<z<0.5), the slope is ~ -0.5 and ~ -1.3 for early-types and starbursts respectively. The steepness of alpha at lower redshift could be qualitatively explained by large numbers of faint dwarf galaxies, perhaps of low surface brightness, which are not detected at higher redshifts.Comment: 24 pages including 5 figures, accepted to ApJ

Standards Competition In The Presence Of Digital Conversion Technology:An Empirical Analysis Of The Flash Memory Card Market

Both theoretical and empirical evidence suggest that in markets with standards competition, strong network effects can make the strong grow stronger and, in some circumstances, even 'tip' the market towards a single, winner-take-all standard. We theorize that in the presence of low cost conversion technologies and digital content, the tendency towards market dominance can be lessened to the point where multiple incompatible standards are viable. Our hypotheses are empirically examined in the context of the flash memory card market where both network effects and high quality conversion are present. The results show that the availability of digital converters reduces the price premium of the leading flash card formats more than of the minority formats. Therefore, producers of the non-dominant standards can be better off with the provision of conversion technology as this technology neutralizes the impact of network effects that would have otherwise been more potent. We discuss both the social and private implications of our findings

Physics at BES-III

This physics book provides detailed discussions on important topics in $\tau$-charm physics that will be explored during the next few years at \bes3 . Both theoretical and experimental issues are covered, including extensive reviews of recent theoretical developments and experimental techniques. Among the subjects covered are: innovations in Partial Wave Analysis (PWA), theoretical and experimental techniques for Dalitz-plot analyses, analysis tools to extract absolute branching fractions and measurements of decay constants, form factors, and CP-violation and \DzDzb-oscillation parameters. Programs of QCD studies and near-threshold tau-lepton physics measurements are also discussed.Comment: Edited by Kuang-Ta Chao and Yi-Fang Wan

Giant Thermoelectric Effect from Transmission Supernodes

We predict an enormous order-dependent quantum enhancement of thermoelectric effects in the vicinity of a higher-order `supernode' in the transmission spectrum of a nanoscale junction. Single-molecule junctions based on 3,3'-biphenyl and polyphenyl ether (PPE) are investigated in detail. The nonequilibrium thermodynamic efficiency and power output of a thermoelectric heat engine based on a 1,3-benzene junction are calculated using many-body theory, and compared to the predictions of the figure-of-merit ZT.Comment: 5 pages, 6 figure

Adaptation of Microelectrode Array Technology for the Study of Anesthesia-Induced Neurotoxicity in the Intact Piglet Brain

Every year, millions of children undergo anesthesia for a multitude of procedures. However, studies in both animals and humans have called into question the safety of anesthesia in children, implicating anesthetics as potentially toxic to the brain in development. To date, no studies have successfully elucidated the mechanism(s) by which anesthesia may be neurotoxic. Animal studies allow investigation of such mechanisms, and neonatal piglets represent an excellent model to study these effects due to their striking developmental similarities to the human brain. This protocol adapts the use of enzyme-based microelectrode array (MEA) technology as a novel way to study the mechanism(s) of anesthesia-induced neurotoxicity (AIN). MEAs enable real-time monitoring of in vivo neurotransmitter activity and offer exceptional temporal and spatial resolution. It is hypothesized that anesthetic neurotoxicity is caused in part by glutamate dysregulation and MEAs offer a method to measure glutamate. The novel implementation of MEA technology in a piglet model presents a unique opportunity for the study of AIN