The Lifecycles of Apps in a Social Ecosystem

Apps are emerging as an important form of on-line content, and they combine aspects of Web usage in interesting ways --- they exhibit a rich temporal structure of user adoption and long-term engagement, and they exist in a broader social ecosystem that helps drive these patterns of adoption and engagement. It has been difficult, however, to study apps in their natural setting since this requires a simultaneous analysis of a large set of popular apps and the underlying social network they inhabit. In this work we address this challenge through an analysis of the collection of apps on Facebook Login, developing a novel framework for analyzing both temporal and social properties. At the temporal level, we develop a retention model that represents a user's tendency to return to an app using a very small parameter set. At the social level, we organize the space of apps along two fundamental axes --- popularity and sociality --- and we show how a user's probability of adopting an app depends both on properties of the local network structure and on the match between the user's attributes, his or her friends' attributes, and the dominant attributes within the app's user population. We also develop models that show the importance of different feature sets with strong performance in predicting app success.Comment: 11 pages, 10 figures, 3 tables, International World Wide Web Conferenc

The Use of Fluorescence Microscopy to Study the Association Between Herpesviruses and Intrinsic Resistance Factors

Intrinsic antiviral resistance is a branch of antiviral defence that involves constitutively expressed cellular proteins that act within individual infected cells. In recent years it has been discovered that components of cellular nuclear structures known as ND10 or PML nuclear bodies contribute to intrinsic resistance against a variety of viruses, notably of the herpesvirus family. Several ND10 components are rapidly recruited to sites that are closely associated with herpes simplex virus type 1 (HSV-1) genomes during the earliest stages of infection, and this property correlates with the efficiency of ND10 mediated restriction of HSV-1 replication. Similar but distinct recruitment of certain DNA damage response proteins also occurs during infection. These recruitment events are inhibited in a normal wild type HSV-1 infection by the viral regulatory protein ICP0. HSV‑1 mutants that do not express ICP0 are highly susceptible to repression through intrinsic resistance factors, but they replicate more efficiently in cells depleted of certain ND10 proteins or in which ND10 component recruitment is inefficient. This article presents the background to this recruitment phenomenon and summaries how it is conveniently studied by fluorescence microscopy

Alternative Supersymmetric Spectra

We describe the features of supersymmetric spectra, alternative to and qualitatively different from that of most versions of the MSSM. The spectra are motivated by extensions of the MSSM with an extra U(1)' gauge symmetry, expected in many grand unified and superstring models, which provide a plausible solution to the mu problem, both for models with supergravity and for gauge-mediated supersymmetry breaking. Typically, many or all of the squarks are rather heavy (larger than one TeV), especially for the first two families, as are the sleptons in the supergravity models. However, there is a richer spectrum of Higgs particles, neutralinos, and (possibly) charginos. Concrete examples of such spectra are presented, and the phenomenological implications are briefly discussed.Comment: 12 pages, LaTe

Relativistic generalizations of gravity-induced localization models

Nonunitary versions of Newtonian gravity leading to wavefunction localization admit natural special-relativistic generalizations. They include the first consistent relativistic localization models. At variance with the unified model of localization and gravity, the purely localizing version requires negative energy fields, which however are less harmful than usual and can be used to build ultraviolet-finite theories.Comment: RevTex, 10 page

The human factor: Re-organisations in public health policy

INTRODUCTION: Public health policy-making activities are currently split between local authority and NHS organisations. Despite an increasing body of research on evidence-based policy (EBP), few studies explore the process of policy-making. Little is known about how policies are made in a local context, or how (scientific) evidence is used. Previous research has ignored the 'human element' in EBP. Social network analysis (SNA) techniques are becoming increasingly important in health policy. This paper describes an innovative study giving a fresh perspective on policy-making processes in public health. METHODS: A social network analysis of public health policy making networks in Greater Manchester based on publicly available data (documents, websites and meeting papers) and an electronic survey, asking actors to nominate those who influenced their own views, those who were powerful, and those who were a source of evidence or information. RESULTS AND CONCLUSIONS: Policy-making networks are described. Formal executive roles are loosely related to perceived influence and power. Evidence-seeking networks are less coherent, with key organisations not represented. These data indicate the importance of collaboration and good relationships between researchers and policy-makers, but few academic researchers with a direct impact on health policy were identified within the networks

A gobal fit to the anomalous magnetic moment, b->s gamma and Higgs limits in the constrained MSSM

New data on the anomalous magnetic moment a_mu of the muon together with the b->s gamma decay rate are considered within the supergravity inspired constrained minimal supersymmetric model. We perform a global statistical chi^2 analysis of these data and show that the allowed region of parameter space is bounded from below by the Higgs limit, which depends on the trilinear coupling and from above by the anomalous magnetic moment a_mu. The newest b->s gamma data deviate 1.7 sigma from recent SM calculations and prefer a similar parameter region as the 2.6 sigma deviation from a_mu.Comment: 12 pages, 7 figs. Refs. update

Identifying public health policymakers' sources of information: comparing survey and network analyses.

Background: Research suggests that policymakers often use personal contacts to find information and advice. However, the main sources of information for public health policymakers are not known. This study aims to describe policymakers' sources of information. A questionnaire survey of public health policymakers across Greater Manchester (GM) was carried out (response rate 48%). All policy actors above Director level involved in public health policy (finding, analyzing or producing information, producing or implementing policy) in GM were included in the sampling frame. Respondents were provided with a list of sources of information and asked which they used (categorical data) and to name specific individuals who acted as sources of information (network data). Data were analyzed using frequencies and network analysis. The most frequently chosen sources of information from the categorical data were NICE, government websites and Directors of Public Health. However, the network data showed that the main sources of information in the network were actually mid-level managers in the NHS, who had no direct expertise in public health. Academics and researchers did not feature in the network. Both survey and network analyses provide useful insights into how policymakers access information. Network analysis offers practical and theoretical contributions to the evidence-based policy debate. Identifying individuals who act as key users and producers of evidence allows academics to target actors likely to use and disseminate their work

Herpesvirus Replication Compartments Originate with Single Incoming Viral Genomes

Previously we described a method to estimate the average number of virus genomes expressed in an infected cell. By analyzing the color spectrum of cells infected with a mixture of isogenic pseudorabies virus (PRV) recombinants expressing three fluorophores, we estimated that fewer than seven incoming genomes are expressed, replicated, and packaged into progeny per cell. In this report, we expand this work and describe experiments demonstrating the generality of the method, as well as providing more insight into herpesvirus replication. We used three isogenic PRV recombinants, each expressing a fluorescently tagged VP26 fusion protein (VP26 is a capsid protein) under the viral VP26 late promoter. We calculated a similar finite limit on the number of expressed viral genomes, indicating that this method is independent of the promoter used to transcribe the fluorophore genes, the time of expression of the fluorophore (early versus late), and the insertion site of the fluorophore gene in the PRV genome (UL versus US). Importantly, these VP26 fusion proteins are distributed equally in punctate virion assembly structures in each nucleus, which improves the signal-to-noise ratio when determining the color spectrum of each cell. To understand how the small number of genomes are distributed among the replication compartments, we used a two-color fluorescent in situ hybridization assay. Most viral replication compartments in the nucleus occupy unique nuclear territories, implying that they arose from single genomes. Our experiments suggest a correlation between the small number of expressed viral genomes and the limited number of replication compartments

The Impacts of a Subglacial Discharge Plume on Calving, Submarine Melting, and Mélange Mass Loss at Helheim Glacier, South East Greenland

Almost half of the Greenland ice sheet’s mass loss occurs through iceberg calving at marine terminating glaciers. The presence of buoyant subglacial discharge plumes at these marine termini are thought to increase mass loss both through submarine melting and by undercutting that consequently increases calving rates. Plume models are used to predict submarine melting and undercutting. However, there are few observations that allow these relationships to be tested. Here we use airborne lidar from the terminus of Helheim Glacier, SE Greenland to measure the bulge induced at the surface by the upwelling plume. We use these measurements to estimate plume discharge rates using a high‐resolution, three‐dimensional plume model. Multi‐year observations of the plume are compared to a record of calving from camera and icequake data. We find no evidence to suggest that the presence of a plume, determined by its visibility at the surface, increases the frequency of major calving events and also show that mass loss at the terminus driven directly by plume discharge is significantly less than mass loss from major calving events. The results suggest that the contribution of direct plume‐driven mass loss at deep marine‐terminating glaciers may be less than at shallower termini