Invasion and Persistence of Infectious Agents in Fragmented Host Populations

One of the important questions in understanding infectious diseases and their prevention and control is how infectious agents can invade and become endemic in a host population. A ubiquitous feature of natural populations is that they are spatially fragmented, resulting in relatively homogeneous local populations inhabiting patches connected by the migration of hosts. Such fragmented population structures are studied extensively with metapopulation models. Being able to define and calculate an indicator for the success of invasion and persistence of an infectious agent is essential for obtaining general qualitative insights into infection dynamics, for the comparison of prevention and control scenarios, and for quantitative insights into specific systems. For homogeneous populations, the basic reproduction ratio plays this role. For metapopulations, defining such an ‘invasion indicator’ is not straightforward. Some indicators have been defined for specific situations, e.g., the household reproduction number . However, these existing indicators often fail to account for host demography and especially host migration. Here we show how to calculate a more broadly applicable indicator for the invasion and persistence of infectious agents in a host metapopulation of equally connected patches, for a wide range of possible epidemiological models. A strong feature of our method is that it explicitly accounts for host demography and host migration. Using a simple compartmental system as an example, we illustrate how can be calculated and expressed in terms of the key determinants of epidemiological dynamics

Data from: Evolutionary branching in complex landscapes

Divergent adaptation to different environments can promote speciation, and it is thus important to consider spatial structure in models of speciation. Earlier theoretical work, however, has been limited to particularly simple types of spatial structure (linear environmental gradients and spatially discrete metapopulations), leaving unaddressed the effects of more realistic patterns of landscape heterogeneity, such as nonlinear gradients and spatially continuous patchiness. To elucidate the consequences of such complex landscapes, we adapt an established spatially explicit individual-based model of evolutionary branching. We show that branching is most probable at intermediate levels of various types of heterogeneity and that different types of heterogeneity have, to some extent, additive effects in promoting branching. In contrast to such additivity, we find a novel refugium effect in which refugia in hostile environments provide opportunities for colonization, thus increasing the probability of branching in patchy landscapes. Effects of patchiness depend on the scale of patches relative to dispersal. Providing a needed connection to empirical research on biodiversity and conservation policy, we introduce empirically accessible spatial environmental metrics that quantitatively predict a landscape’s branching propensity

Apputveckling för barn

Sammanfattning Dagens barn växer upp i ett samhälle där tekniker som pekskärmar, pekplattor och mobiltelefoner finns överallt och har blivit en del av vår vardag. Detta medför en ökad användning av appar utformade för dessa enheter och det finns således en intressant aspekt ur ett utvecklingsperspektiv samt hur man bör gå till väga för att på bästa sätt skapa appar ämnade för barn. Syftet med denna studie är att undersöka generella designprinciper som applikationsutvecklare använder vid utveckling av appar för barn som slutanvändare och därtill undersöka hur dessa appar tilltalar och underlättar barns handhavande och interaktion. Detta har lett oss fram till vår frågeställning: Hur förhåller sig utvecklare till generella designprinciper vid skapandet av appar ämnade för barn? Utifrån denna frågeställning undersökte vi relevant forskning inom området för att kunna ta fram ett antal generella designprinciper vid apputveckling samt ta reda på vad som är viktigt att ha i åtanke när man skapar appar för barn. För att få svar på frågeställningen genomförde vi en kvalitativ intervjustudie med professionella apputvecklare som utvecklar barnappar för att få deras syn på generella designprinciper. Slutsatserna av vår studie pekar på att de utvecklare vi har intervjuat förhåller sig positivt till de valda generella designprinciperna, men det är inte så att de följer dem som någon slags mall eller manual för hur man designar appar för barn. Dessutom har vi utifrån de genomförda intervjuerna med utvecklarna fått upp ögonen för nya aspekter gällande utveckling av appar för barn.Today's children grow up in a society where technologies such as touch screens, touchpads and cell phones are everywhere and have become part of our everyday life. This results in an increased use of Apps designed for these units and there is thus an interesting aspect from a development perspective, and how to go about the best way to create apps intended for children. The purpose of this study is to investigate the general design principles that application developers can use when developing apps for the child as an end user and in addition examine how these apps appeal to and facilitate the child's operation and interaction. This has led us to our question: How do the developers relate to general design principles when creating apps meant for children? With this question in mind we examined relevant research in order to get a set of general design principles regarding app development and find the most important aspects what when creating apps for kids. To answer this question, we conducted a qualitative interview study with professional app developers to seek their views on general design principles. The findings of our study suggest that the developers we interviewed are favorable to the selected general design principles, but it's not that they follow them as a template or guide for how to design for children. Moreover, the interviews has brought new light regarding other aspects when developing apps for children

Stopping boundary condition data

Stopping boundary condition dat

Model video

a video of one model realizatio

A readme file describing the files in this archive

A readme file describing the files in this archiv