Experimental Evaluation of Different Pricing Mechanisms for Content Distribution over Peer to Peer Networks

This paper extends previous work by the authors in which they propose a dynamic distribution model based on modified economic growth theory to determine file distribution patterns in peer-to-peer networks. Although the theoretical model provides a good foundation for exploring different pricing mechanisms for peer-to-peer networks, there are several issues that remain unexplored because of computational difficulties. In this paper, we use the methods of experimental economics to create a sequence of experimental designs to explore some of these issues. The designs mimic the structure of the industry, the type of current and future property rights, some technical constraints, and the strategic interactions between the different actors

THE IMPACT OF IT-ENABLED COORDINATION ON GROUP PERFORMANCE IN AN ELECTRONIC GROUP-BUYING MARKET

This article presents an evaluation approach for alternative electronic market designs and examines the impact of introducing an IT-enabled innovation (a social communication tool to support group coordination) in an online group-buying market in terms of group decision-making and economic performance. Drawing on theory from economics, decision theory, and information systems, we present a competitive arousal model for a social buying setting that posits that introducing competitive arousal among buyers reduces buyer profits and that social facilitation can mitigate these costs through better task completion and time to completion rates. Using an economic experiment, we found that rivalry has a negative effect on buyer profits but also that pressure increases the efficiency of social communication in terms of group formation. We discuss the implications of these results

Supporting Better Communication in Academic Communities of Practice: An Empirical Study of AIS/ISWORLD

The AIS/ISWorld Mailing List is the premier global communication tool for academics in the information systems area. This paper employs content analysis of archival data to report on an exploratory study of the usage of ISWorld over a four-year period between 2002 and 2006. We develop a coding scheme based on two theoretically distinct levels of communication and examine how ISWorld community members use the mailing list for the purposes of information dissemination, knowledge exchange, and knowledge creation. Our analysis yields important insights regarding the evolution of the ISWorld Mailing List, user characteristics and communication patterns, as well as the alignment between the community’s stated organizational goals and the design of the communication tool. Our findings show that the ISWorld Mailing List offers a highly efficient communication tool for knowledge dissemination to the IS community but also that its usage has been shifting more strongly towards information broadcasting and away from interactive knowledge exchange and creation. The paper concludes with some design and governance related recommendations for making ISWorld a more effective communication tool for the IS community

Infinite dimensional Lie algebras in 4D conformal quantum field theory

The concept of global conformal invariance (GCI) opens the way of applying algebraic techniques, developed in the context of 2-dimensional chiral conformal field theory, to a higher (even) dimensional space-time. In particular, a system of GCI scalar fields of conformal dimension two gives rise to a Lie algebra of harmonic bilocal fields, V_m(x,y), where the m span a finite dimensional real matrix algebra M closed under transposition. The associative algebra M is irreducible iff its commutant M' coincides with one of the three real division rings. The Lie algebra of (the modes of) the bilocal fields is in each case an infinite dimensional Lie algebra: a central extension of sp(infty,R) corresponding to the field R of reals, of u(infty,infty) associated to the field C of complex numbers, and of so*(4 infty) related to the algebra H of quaternions. They give rise to quantum field theory models with superselection sectors governed by the (global) gauge groups O(N), U(N), and U(N,H)=Sp(2N), respectively.Comment: 16 pages, with minor improvements as to appear in J. Phys.

The Panchromatic Hubble Andromeda Treasury. Progression of Large-Scale Star Formation across Space and Time in M31

We investigate the clustering of early-type stars younger than 300 Myr on galactic scales in M31. Based on the stellar photometric catalogs of the Panchromatic Hubble Andromeda Treasury program that also provides stellar parameters derived from the individual energy distributions, our analysis is focused on the young stars in three star-forming regions, located at galactocentric distances of about 5, 10, and 15 kpc, corresponding to the inner spiral arms, the ring structure, and the outer arm, respectively. We apply the two-point correlation function to our selected sample to investigate the clustering behavior of these stars across different time- and length-scales. We find that young stellar structure survives across the whole extent of M31 longer than 300 Myr. Stellar distribution in all regions appears to be self-similar, with younger stars being systematically more strongly clustered than the older, which are more dispersed. The observed clustering is interpreted as being induced by turbulence, the driving source for which is probably gravitational instabilities driven by the spiral arms, which are stronger closer to the galactic centre.Comment: 10 pages, 5 figures. To appear in "LESSONS FROM THE LOCAL GROUP - A Conference in Honour of David Block and Bruce Elmegreen" eds. Freeman, K.C., Elmegreen, B.G., Block, D.L. & Woolway, M. (Springer: New York

Occurrence of testicular microlithiasis in androgen insensitive hypogonadal mice

<b>Background</b>: Testicular microliths are calcifications found within the seminiferous tubules. In humans, testicular microlithiasis (TM) has an unknown etiology but may be significantly associated with testicular germ cell tumors. Factors inducing microlith development may also, therefore, act as susceptibility factors for malignant testicular conditions. Studies to identify the mechanisms of microlith development have been hampered by the lack of suitable animal models for TM.<BR/> <b>Methods</b>: This was an observational study of the testicular phenotype of different mouse models. The mouse models were: cryptorchid mice, mice lacking androgen receptors (ARs) on the Sertoli cells (SCARKO), mice with a ubiquitous loss of androgen ARs (ARKO), hypogonadal (hpg) mice which lack circulating gonadotrophins, and hpg mice crossed with SCARKO (hpg.SCARKO) and ARKO (hpg.ARKO) mice.<BR/> <b>Results</b>: Microscopic TM was seen in 94% of hpg.ARKO mice (n=16) and the mean number of microliths per testis was 81 +/- 54. Occasional small microliths were seen in 36% (n=11) of hpg testes (mean 2 +/- 0.5 per testis) and 30% (n=10) of hpg.SCARKO testes (mean 8 +/- 6 per testis). No microliths were seen in cryptorchid, ARKO or SCARKO mice. There was no significant effect of FSH or androgen on TM in hpg.ARKO mice.<BR/> <b>Conclusions</b>: We have identified a mouse model of TM and show that lack of endocrine stimulation is a cause of TM. Importantly, this model will provide a means with which to identify the mechanisms of TM development and the underlying changes in protein and gene expression