63 research outputs found

    Large Deviations and Exit-times for reflected McKean-Vlasov equations with self-stabilizing terms and superlinear drifts

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    We study a class of reflected McKean-Vlasov diffusions over a convex domain with self-stabilizing coefficients. This includes coefficients that do not satisfy the classical Wasserstein Lipschitz condition. Further, the process is constrained to a (not necessarily bounded) convex domain by a local time on the boundary. These equations include the subclass of reflected self-stabilizing diffusions that drift towards their mean via a convolution of the solution law with a stabilizing potential. Firstly, we establish existence and uniqueness results for this class and address the propagation of chaos. We work with a broad class of coefficients, including drift terms that are locally Lipschitz in spatial and measure variables. However, we do not rely on the boundedness of the domain or the coefficients to account for these non-linearities and instead use the self-stabilizing properties. We prove a Freidlin-Wentzell type Large Deviations Principle and an Eyring-Kramer's law for the exit-time from subdomains contained in the interior of the reflecting domain.Comment: 41 page

    Propositionalism without propositions, objectualism without objects

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    Propositionalism is the view that all intentional states are propositional states, which are states with a propositional content, while objectualism is the view that at least some intentional states are objectual states, which are states with objectual contents, such as objects, properties, and kinds. This paper argues that there are two distinct ways of understanding propositionalism and objectualism: (1) as views about the deep nature of the contents of intentional states, and (2) as views about the superficial character of the contents of intentional states. I argue that we should understand the views in the second way. I also argue that the propositionalism debate is fairly independent from debates over the deep nature of intentionality, and that this has implications for arguments for propositionalism and objectualism from claims about the nature of intentional content. I close with a short discussion of how related points apply to the debate over singular content

    Spatial analysis of plague in California: niche modeling predictions of the current distribution and potential response to climate change

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    <p>Abstract</p> <p>Background</p> <p>Plague, caused by the bacterium <it>Yersinia pestis</it>, is a public and wildlife health concern in California and the western United States. This study explores the spatial characteristics of positive plague samples in California and tests Maxent, a machine-learning method that can be used to develop niche-based models from presence-only data, for mapping the potential distribution of plague foci. Maxent models were constructed using geocoded seroprevalence data from surveillance of California ground squirrels (<it>Spermophilus beecheyi</it>) as case points and Worldclim bioclimatic data as predictor variables, and compared and validated using area under the receiver operating curve (AUC) statistics. Additionally, model results were compared to locations of positive and negative coyote (<it>Canis latrans</it>) samples, in order to determine the correlation between Maxent model predictions and areas of plague risk as determined via wild carnivore surveillance.</p> <p>Results</p> <p>Models of plague activity in California ground squirrels, based on recent climate conditions, accurately identified case locations (AUC of 0.913 to 0.948) and were significantly correlated with coyote samples. The final models were used to identify potential plague risk areas based on an ensemble of six future climate scenarios. These models suggest that by 2050, climate conditions may reduce plague risk in the southern parts of California and increase risk along the northern coast and Sierras.</p> <p>Conclusion</p> <p>Because different modeling approaches can yield substantially different results, care should be taken when interpreting future model predictions. Nonetheless, niche modeling can be a useful tool for exploring and mapping the potential response of plague activity to climate change. The final models in this study were used to identify potential plague risk areas based on an ensemble of six future climate scenarios, which can help public managers decide where to allocate surveillance resources. In addition, Maxent model results were significantly correlated with coyote samples, indicating that carnivore surveillance programs will continue to be important for tracking the response of plague to future climate conditions.</p

    Customs Law

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    This article summarizes important developments in 2014 in customs law, including U.S. judicial decisions, trade, legislative, administrative, and executive developments, as well as Canadian and European legal developments

    The ecology of a host-parasite relationship: haemogregarines and the eastern water skink, Eulamprus quoyii

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    The study of wildlife disease has gained importance in the last two decades as a result of theoretical insights into its possible roles in host evolution, population biology and ecology. However, knowledge of how hosts and parasites interact in natural systems remains limited, and there is a critical need for further research. Therefore, this thesis examines the ecology and interactions between wild populations of hosts, the eastern water skink, Eulamprus quoyii, and a parasite, the haemogregarine protist Hepatozoon hinuliae. I carried out a two-year markrecapture study of eastern water skinks at Blackdown Tableland, Queensland, Australia, and analysed blood slides to measure haemogregarine blood parasite infection. Prevalence (the proportion of the host population infected) increased with host age, did not differ between the sexes, and varied little during the two-year study. Parasite load (the intensity of infection within individuals) was significantly higher in males than in females, and is highly correlated in individuals over time. Eastern water skinks are viviparous, and therefore reproductive output can be accurately measured by housing pregnant females in captivity shortly before they gave birth. High haemogregarine loads reduced female water skink fecundity, by approximately one offspring per litter, compared to females with low parasite loads. Body condition and fat reserves were not responsible for this reduced fecundity. There was no effect of maternal haemogregarine parasite load on offspring size/number trade -offs, or on the performance of offspring measured by growth rates, sprint speed or competitive ability. Using microsatellite markers, I carried out a preliminary investigation of the effect of blood parasites on female mating strategy. Fifty percent of analysed litters showed evidence of multiple sires, but the propensity to multiple mating was unaffected by female haemogregarine parasite load. Because Eulamprus quoyii occupies a large geographical range spanning the Australian tropical and temperate zones, I investigated whether patterns of parasite abundance are affected by climate. Parasite load, but not prevalence, is related to temperature, but is independent of rainfall. In conclusion, I argue that haemogregarine blood parasites affect the life-history of their natural host, the eastern water skink, and that continued study of the Blackdown Tableland population should offer further insights into the evolutionary ecology of a wild host-parasite relationship

    Epizootiology of blood parasites in an Australian lizard: a mark-recapture study of a natural population

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    The dynamics of a naturally endemic blood parasite Hepatozoon hinuliae) were studied in a lizard (Eulamprus quoyii) host population, using 2 years of longitudinal data. We investigated how parasite abundance in the population varied over time, examined whether certain host sub-populations were more prone to infection, and compared parasite loads in relation to host reproductive behaviour. We recorded blood parasite infections of 331 individuals, obtained in 593 captures. Prevalence (the proportion of the host population infected) of blood parasites was high; approximately 66% of the lizard population was infected. Probability of infection increased with host age and size, but did not differ between the sexes. Within individuals, parasite load (the intensity of infection within individuals) did not vary over time, and was independent of host reproductive behaviour. Parasite load was significantly higher in males compared to females

    Tick-borne Pathogens in Northwestern California, USA

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    Distribution of the Lyme Disease Spirochete Borrelia burgdorferi in Naturally and Experimentally Infected Western Gray Squirrels (Sciurus griseus)

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    The dynamics of Borrelia burgdorferi infections within its natural hosts are poorly understood. We necropsied four wild-caught western gray squirrels (Sciurus griseus) that were acquired during a previous study that evaluated the reservoir competence of this rodent for the Lyme disease spirochete. One animal was infected experimentally, whereas the others were infected in the wild before capture. To investigate dissemination of B. burgdorferi and concurrent histopathologic lesions in different tissues, blood specimens, synovial and cerebrospinal fluid, ear-punch biopsies, and diverse tissue samples from skin and various organs were taken and examined by culture, polymerase chain reaction, and histology. Borrelia-positive cultures were obtained from three of the squirrels, that is, from skin biopsies (7 of 20 samples), ear-punch biopsies (2 of 8), and one (1 of 5) lymph node. Sequencing of amplicons confirmed B. burgdorferi sensu stricto (s.s.) infection in 9 of 10 culture-positive samples and in DNA extracted from all 10 positive cultures. The experimentally infected squirrel yielded most of the positive samples. In contrast, bodily fluids, all other organ specimens from these animals, and all samples from one naturally infected squirrel were negative for Borrelia for both assays. None of the necropsied squirrels exhibited specific clinical signs associated with B. burgdorferi. Similarly, necropsy and histological examination of tissues indicated the presence of underlying infectious processes, none of which could be ascribed conclusively to B. burgdorferi infection. Based on these results, obtained from a small number of animals investigated at a single time point, we suggest that B. burgdorferi s.s. infection in S. griseus may result in rather localized dissemination of spirochetes, and that mild or nonclinical disease might be more common after several months of infection duration. Since spirochetes could be detected in squirrels 7–21 months postinfection, we conclude that S. griseus can infect Ixodes pacificus ticks with B. burgdorferi s.s. trans-seasonally
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