A Tandem Fluid Network with L\'evy Input in Heavy Traffic

In this paper we study the stationary workload distribution of a fluid tandem queue in heavy traffic. We consider different types of L\'evy input, covering compound Poisson, $\alpha$-stable L\'evy motion (with $1<\alpha<2$), and Brownian motion. In our analysis we separately deal with L\'evy input processes with increments that have finite and infinite variance. A distinguishing feature of this paper is that we do not only consider the usual heavy-traffic regime, in which the load at one of the nodes goes to unity, but also a regime in which we simultaneously let the load of both servers tend to one, which, as it turns out, leads to entirely different heavy-traffic asymptotics. Numerical experiments indicate that under specific conditions the resulting simultaneous heavy-traffic approximation significantly outperforms the usual heavy-traffic approximation

Show, don’t just tell:Photo stories to support people with limited health literacy

Mensen met beperkte gezondheidsvaardigheden (ook wel: gezondheidsgeletterdheid) hebben vaak moeite met het begrijpen van informatie in folders en brochures én met gesprekken met zorgprofessionals. In dit proefschrift doen we verslag van onderzoek naar de vraag hoe we tot folders en brochures kunnen komen waar mensen met beperkte gezondheidsvaardigheden meer aan hebben. Daarbij kijken we naar methoden om de begrijpelijkheid van gezondheidsinformatie te vergroten en tegelijk naar methoden om gesprekken met zorgprofessionals te ondersteunen. Het centrale thema van dit proefschrift is het gebruik van fotostrips in gezondheidscommunicatie. Fotostrips zijn beeldende verhalen met foto’s en bijschriften. Eerder onderzoek laat zien dat zulke verhalen mensen met beperkte gezondheidsvaardigheden kunnen ondersteunen. In verschillende onderzoeken met deelnemers uit de doelgroep verkenden we wat het beste ontwerp voor fotostrips zou kunnen zijn en onderzochten we de effecten van zulke fotostrips over gesprekken met zorgprofessionals. Samen met ouderen creëerden we fotostrips over patiënt-doktergesprekken, waarin de thema’s en strategieën terugkwamen die ouderen zelf hadden ingebracht. Hoewel ouderen in een kwalitatief onderzoek de fotostrips duidelijk verkozen boven een vergelijkbare traditionele brochure vonden we in een kwantitatief onderzoek geen significante verschillen. Patiënten in wachtkamers van huisartsenprakijken rapporteerden echter dat zij de fotostrips in de wachtkamers vaker opmerkten dan de traditionele brochures. Samenvattend: fotostrips zijn een veelbelovend middel om mensen met beperkte gezondheidsvaardigheden te ondersteunen. Verder onderzoek is nodig om na te gaan wat de impact is van fotostrips op patiënt-doktergesprekken

Resistively-shunted superconducting quantum point contacts

We have studied the Josephson dynamics of resistively-shunted ballistic superconducting quantum point contacts at finite temperatures and arbitrary number of conducting modes. Compared to the classical Josephson dynamics of tunnel junctions, dynamics of quantum point contacts exhibits several new features associated with temporal fluctuations of the Josephson potential caused by fluctuations in the occupation of the current-carrying Andreev levels.Comment: 5 pages, RevTex, 3 postscript figures include

"The dearest of our possessions": applying Floridi's information privacy concept in models of information behavior and information literacy

This conceptual paper argues for the value of an approach to privacy in the digital information environment informed by Luciano Floridi's philosophy of information and information ethics. This approach involves achieving informational privacy, through the features of anonymity and obscurity, through an optimal balance of ontological frictions. This approach may be used to modify models for information behavior and for information literacy, giving them a fuller and more effective coverage of privacy issues in the infosphere. For information behavior, the Information Seeking and Communication Model, and the Information Grounds conception, are most appropriate for this purpose. For information literacy, the metaliteracy model, using a modification a privacy literacy framework, is most suitable

Gamow-Teller strength in 54Fe and 56Fe

Through a sequence of large scale shell model calculations, total Gamow-Teller strengths ($S_+$ and $S_-$) in $^{54}$Fe and $^{56}$Fe are obtained. They reproduce the experimental values once the $\sigma\tau$ operator is quenched by the standard factor of $0.77$. Comparisons are made with recent Shell Model Monte Carlo calculations. Results are shown to depend critically on the interaction. From an analysis of the GT+ and GT$-$ strength functions it is concluded that experimental evidence is consistent with the $3(N-Z)$ sum rule.Comment: 6 pages, RevTeX 3.0 using psfig, 7 Postscript figures included using uufile

Social network analysis shows direct evidence for social transmission of tool use in wild chimpanzees

The authors are grateful to the Royal Zoological Society of Scotland for providing core funding for the Budongo Conservation Field Station. The fieldwork of CH was funded by the Leverhulme Trust, the Lucie Burgers Stichting, and the British Academy. TP was funded by the Canadian Research Chair in Continental Ecosystem Ecology, and received computational support from the Theoretical Ecosystem Ecology group at UQAR. The research leading to these results has received funding from the People Programme (Marie Curie Actions) and from the European Research Council under the European Union's Seventh Framework Programme (FP7/2007–2013) REA grant agreement n°329197 awarded to TG, ERC grant agreement n° 283871 awarded to KZ. WH was funded by a BBSRC grant (BB/I007997/1).Social network analysis methods have made it possible to test whether novel behaviors in animals spread through individual or social learning. To date, however, social network analysis of wild populations has been limited to static models that cannot precisely reflect the dynamics of learning, for instance, the impact of multiple observations across time. Here, we present a novel dynamic version of network analysis that is capable of capturing temporal aspects of acquisition-that is, how successive observations by an individual influence its acquisition of the novel behavior. We apply this model to studying the spread of two novel tool-use variants, "moss-sponging'' and "leaf-sponge re-use,'' in the Sonso chimpanzee community of Budongo Forest, Uganda. Chimpanzees are widely considered the most "cultural'' of all animal species, with 39 behaviors suspected as socially acquired, most of them in the domain of tool-use. The cultural hypothesis is supported by experimental data from captive chimpanzees and a range of observational data. However, for wild groups, there is still no direct experimental evidence for social learning, nor has there been any direct observation of social diffusion of behavioral innovations. Here, we tested both a static and a dynamic network model and found strong evidence that diffusion patterns of moss-sponging, but not leaf-sponge re-use, were significantly better explained by social than individual learning. The most conservative estimate of social transmission accounted for 85% of observed events, with an estimated 15-fold increase in learning rate for each time a novice observed an informed individual moss-sponging. We conclude that group-specific behavioral variants in wild chimpanzees can be socially learned, adding to the evidence that this prerequisite for culture originated in a common ancestor of great apes and humans, long before the advent of modern humans.Publisher PDFPeer reviewe

Subharmonic Shapiro steps and assisted tunneling in superconducting point contacts

We analyze the current in a superconducting point contact of arbitrary transmission in the presence of a microwave radiation. The interplay between the ac Josephson current and the microwave signal gives rise to Shapiro steps at voltages V = (m/n) \hbar \omega_r/2e, where n,m are integer numbers and \omega_r is the radiation frequency. The subharmonic steps (n different from 1) are a consequence of the ocurrence of multiple Andreev reflections (MAR) and provide an unambiguous signature of the peculiar ac Josephson effect at high transmission. Moreover, the dc current exhibits a rich subgap structure due to photon-assisted MARs.Comment: Revtex, 4 pages, 4 figure