Combining a Dispersal Model with Network Theory to Assess Habitat Connectivity

Assessing the potential for threatened species to persist and spread within fragmented landscapes requires the identification of core areas that can sustain resident populations and dispersal corridors that can link these core areas with isolated patches of remnant habitat. We developed a set of GIS tools, simulation methods, and network analysis procedures to assess potential landscape connectivity for the Delmarva fox squirrel (DFS; Sciurus niger cinereus), an endangered species inhabiting forested areas on the Delmarva Peninsula, USA. Information on the DFS’s life history and dispersal characteristics, together with data on the composition and configuration of land cover on the peninsula, were used as input data for an individual-based model to simulate dispersal patterns of millions of squirrels. Simulation results were then assessed using methods from graph theory, which quantifies habitat attributes associated with local and global connectivity. Several bottlenecks to dispersal were identified that were not apparent from simple distance-based metrics, highlighting specific locations for landscape conservation, restoration, and/or squirrel translocations. Our approach links simulation models, network analysis, and available field data in an efficient and general manner, making these methods useful and appropriate for assessing the movement dynamics of threatened species within landscapes being altered by human and natural disturbances

Long-term safety of unopposed estrogen used by women surviving myocardial infarction : 14 year follow-up of the ESPRIT randomised controlled trial

Peer reviewedPostprin

Differences of Cycling Experiences and Perceptions between E-Bike and Bicycle Users in the United States

E-bikes are bicycles that provide pedal-assistance to aid people in cycling. Because of the potential of promoting sustainable transportation, more attention has been focused on the e-bike market. This paper investigates the differences of the cycling experience and perceptions between e-bike and conventional bicycle users, using samples drawn from independent bicycle dealer customers. A total of 806 respondents in the United States took the on-line survey, including 363 e-bike-owning respondents. The results show that e-bikes play a more important role in utilitarian travel, such as commuting and running errands, compared to a conventional bicycle. Conventional bicycle-owning respondents use their bicycles more for recreation and exercise. Also, e-bike owners tend to bike longer distances and take more trips per week. Both e-bike respondents and bicycle respondents stated that improved health was a key factor for cycling, while Millennials and Generation X respondents cycle to save time and improve the environment. Finally, an ordered logit model is proposed for evaluating factors that influence interest in future e-bike ownership. Travel purpose, e-bike familiarity, annual household income, and education level are statistically significant factors in the model. These findings begin to provide insight and a profile of potential new markets for e-bikes in the United States

Using airborne LiDAR Survey to explore historic-era archaeological landscapes of Montserrat in the eastern Caribbean

This article describes what appears to be the first archaeological application of airborne LiDAR survey to historic-era landscapes in the Caribbean archipelago, on the island of Montserrat. LiDAR is proving invaluable in extending the reach of traditional pedestrian survey into less favorable areas, such as those covered by dense neotropical forest and by ashfall from the past two decades of active eruptions by the Soufrière Hills volcano, and to sites in localities that are inaccessible on account of volcanic dangers. Emphasis is placed on two aspects of the research: first, the importance of ongoing, real-time interaction between the LiDAR analyst and the archaeological team in the field; and second, the advantages of exploiting the full potential of the three-dimensional LiDAR point cloud data for purposes of the visualization of archaeological sites and features

A utilitarian antagonist: the zombie in popular video games

This article takes as its starting point the prevalence of the zombie in video games. I argue that, although the zombie games often superficially resemble filmic texts in their use of aesthetic and narrative, they must be understood, less as a set of conventions and thematic metaphors in the way that the zombie text has been read in film and television scholarship, and more as a utilisation of the zombie as a utilitarian antagonist that facilitates and permits the pleasures of violence and fantasy in video game play. Beginning with the Resident Evil and Left 4 Dead series of games I examine the way that games necessarily update the notion zombie as mass antagonist via the need to vary gameplay activity through different styles of adversary for players. At the same time I will demonstrate that, far from simply being the province of the survival horror genre, the zombie appears across an array of game forms, game cultures and game productions. The zombie highlights the participatory nature of game culture in the array of zombie 'mods' that users create to transform existing games into zombie based games, in particular in relation to titles such as the Call of Duty series. At the other end of the production spectrum the zombie features heavily in the little studied area of online flash games where the zombie can be found in a variety of game genres and forms. The zombie here often operates as a pastiche of popular zombie narratives in survival games (The Last Stand), parodic engagements with zombie conventions (Jetpacks and Zombies) or play with the notion of zombie pandemics (the Infectionator games). Here I situate the zombie game as a aesthetic genre that works to provide an easily understandable context for such interactive genres as survival horror, text adventures, shooting games, physics games and driving games, with the popularity of these enough to drive numerous dedicated hosting and link sites such as zombiegames.net. The pastiche element of these games extends into gamers social engagement with games. Online debates over the the appropriate actions or preparation for a zombie holocaust are commonplace on the internet in such spaces as Zombieresearch.net. Whilst many of these sites feature decidedly tongue in cheek engagement with the notion of the zombie apocalypse, the users of fora for games like Left 4 Dead and Dead Island tend to debate this directly in the terms of the games themselves, discussing their relative merits or realism. Some of these games also highlight the specific pleasures of identifying the zombie as protagonist of sorts. In discussing this I will return to online gaming and the Left 4 Dead games in which players may compete online as part of the zombie horde. Such games raise major questions for the issues of identification and immersion that are said to be at the centre of the game experience. I will also explore the parodic pleasures of many flash games that situate the player in the role of spreading zombie infections. Throughout this article I aim to demonstrate that the zombie in game culture is less a cultural metaphor than a combination of utilitarian antagonist and a persistent aesthetic; a means of providing style or pleasure to many games that relies on the intertextual and flexible nature of the zombie as popular cultural phenomenon

Cardiac cell modelling: Observations from the heart of the cardiac physiome project

In this manuscript we review the state of cardiac cell modelling in the context of international initiatives such as the IUPS Physiome and Virtual Physiological Human Projects, which aim to integrate computational models across scales and physics. In particular we focus on the relationship between experimental data and model parameterisation across a range of model types and cellular physiological systems. Finally, in the context of parameter identification and model reuse within the Cardiac Physiome, we suggest some future priority areas for this field

Predictors of measles vaccination coverage among children 6-59 months of age in the Democratic Republic of the Congo.

BackgroundMeasles is a significant contributor to child mortality in the Democratic Republic of the Congo (DRC), despite routine immunization programs and supplementary immunization activities (SIA). Further, national immunization coverage levels may hide disparities among certain groups of children, making effective measles control even more challenging. This study describes measles vaccination coverage and reporting methods and identifies predictors of vaccination among children participating in the 2013-2014 DRC Demographic and Health Survey (DHS).MethodsWe examined vaccination coverage of 6947 children aged 6-59 months. A multivariate logistic regression model was used to identify predictors of vaccination among children reporting vaccination via dated card in order to identify least reached children. We also assessed spatial distribution of vaccination report type by rural versus urban residence.ResultsUrban children with educated mothers were more likely to be vaccinated (OR = 4.1, 95% CI: 1.6, 10.7) versus children of mothers with no education, as were children in wealthier rural families (OR = 2.9, 95% CI: 1.9, 4.4). At the provincial level, urban areas more frequently reported vaccination via dated card than rural areas.ConclusionsResults indicate that, while the overall coverage level of 70% is too low, socioeconomic and geographic disparities also exist which could make some children even less likely to be vaccinated. Dated records of measles vaccination must be increased, and groups of children with the greatest need should be targeted. As access to routine vaccination services is limited in DRC, identifying and targeting under-reached children should be a strategic means of increasing country-wide effective measles control

Farm and Ranch Income Tax Management.

12 p

Compositionality, stochasticity and cooperativity in dynamic models of gene regulation

We present an approach for constructing dynamic models for the simulation of gene regulatory networks from simple computational elements. Each element is called a ``gene gate'' and defines an input/output-relationship corresponding to the binding and production of transcription factors. The proposed reaction kinetics of the gene gates can be mapped onto stochastic processes and the standard ode-description. While the ode-approach requires fixing the system's topology before its correct implementation, expressing them in stochastic pi-calculus leads to a fully compositional scheme: network elements become autonomous and only the input/output relationships fix their wiring. The modularity of our approach allows to pass easily from a basic first-level description to refined models which capture more details of the biological system. As an illustrative application we present the stochastic repressilator, an artificial cellular clock, which oscillates readily without any cooperative effects.Comment: 15 pages, 8 figures. Accepted by the HFSP journal (13/09/07

Indeterminacy of Spatiotemporal Cardiac Alternans

Cardiac alternans, a beat-to-beat alternation in action potential duration (at the cellular level) or in ECG morphology (at the whole heart level), is a marker of ventricular fibrillation, a fatal heart rhythm that kills hundreds of thousands of people in the US each year. Investigating cardiac alternans may lead to a better understanding of the mechanisms of cardiac arrhythmias and eventually better algorithms for the prediction and prevention of such dreadful diseases. In paced cardiac tissue, alternans develops under increasingly shorter pacing period. Existing experimental and theoretical studies adopt the assumption that alternans in homogeneous cardiac tissue is exclusively determined by the pacing period. In contrast, we find that, when calcium-driven alternans develops in cardiac fibers, it may take different spatiotemporal patterns depending on the pacing history. Because there coexist multiple alternans solutions for a given pacing period, the alternans pattern on a fiber becomes unpredictable. Using numerical simulation and theoretical analysis, we show that the coexistence of multiple alternans patterns is induced by the interaction between electrotonic coupling and an instability in calcium cycling.Comment: 20 pages, 10 figures, to be published in Phys. Rev.