73 research outputs found

    The Role of Canine Distemper Virus and Persistent Organic Pollutants in Mortality Patterns of Caspian Seals (Pusa caspica)

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    Persistent organic pollutants are a concern for species occupying high trophic levels since they can cause immunosuppression and impair reproduction. Mass mortalities due to canine distemper virus (CDV) occurred in Caspian seals (Pusa caspica), in spring of 1997, 2000 and 2001, but the potential role of organochlorine exposure in these epizootics remains undetermined. Here we integrate Caspian seal mortality data spanning 1971-2008, with data on age, body condition, pathology and blubber organochlorine concentration for carcases stranded between 1997 and 2002. We test the hypothesis that summed PCB and DDT concentrations contributed to CDV associated mortality during epizootics. We show that age is the primary factor explaining variation in blubber organochlorine concentrations, and that organochlorine burden, age, sex, and body condition do not account for CDV infection status (positive/negative) of animals dying in epizootics. Most animals (57%, n = 67) had PCB concentrations below proposed thresholds for toxic effects in marine mammals (17 μg/g lipid weight), and only 3 of 67 animals had predicted TEQ values exceeding levels seen to be associated with immune suppression in harbour seals (200 pg/g lipid weight). Mean organonchlorine levels were higher in CDV-negative animals indicating that organochlorines did not contribute significantly to CDV mortality in epizootics. Mortality monitoring in Azerbaijan 1971-2008 revealed bi-annual stranding peaks in late spring, following the annual moult and during autumn migrations northwards. Mortality peaks comparable to epizootic years were also recorded in the 1970s-1980s, consistent with previous undocumented CDV outbreaks. Gompertz growth curves show that Caspian seals achieve an asymptotic standard body length of 126-129 cm (n = 111). Males may continue to grow slowly throughout life. Mortality during epizootics may exceed the potential biological removal level (PBR) for the population, but the low frequency of epizootics suggest they are of secondary importance compared to anthropogenic sources of mortality such as fishing by-catch

    On regularity of transition probabilities and invariant measures of singular diffusions under minimal conditions

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    Bogachev VI, Krylov NV, Röckner M. On regularity of transition probabilities and invariant measures of singular diffusions under minimal conditions. Communications in Partial Differential Equations . 2001;26(11-12):2037-2080.Let A = (a(ij)) be a matrix-valued Borel mapping on a domain Omega subset of R-d, let b = (b(i)) be a vector field on Omega, and let L-A,L-bphi = a(ij)partial derivative(xi)partial derivative(xj)phi + b(i)partial derivative(xi)phi. We study Borel measures mu on Omega that satisfy the elliptic equation L-A,L-bmu* = 0 in the weak sense: integral L(A,b)phidmu = 0 for all phi is an element of C-0(infinity)(Omega). We prove that, under mild conditions, mu has a density. If A is locally uniformly nondegenerate, A is an element of H-loc(p,1) and b is an element of L-loc(p) for some p > d, then this density belongs to H-loc(p,1). Actually, we prove Sobolev regularity for solutions of certain generalized nonlinear elliptic inequalities. Analogous results are obtained in the parabolic case. These results are applied to transition probabilities and invariant measures of diffusion processes

    Tables of Laguerre polynomials and functions

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    Tables of Laguerre Polynomials and Function

    Saddlepoint approximations for subordinator processes

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    Hadamard and Dragomir-Agarwal Inequalities, the Euler Formulae and Convex Functions

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