65 research outputs found

    Wpływ jakości olejów silnikowych na zanieczyszczenie powietrza atmosferycznego składnikami spalin emitowanymi przez pojazdy samochodowe

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    Artykuł porusza zagadnienia wpływu oleju silnikowego na wielkość emisji CO2 przez pojazdy samochodowe. Przedstawiono związki między smarowaniem silników, a zużyciem paliwa i emisją CO2. Skupiono się na analizie wpływu własności reologicznych oleju silnikowego w szerokim zakresie temperatury i ciśnienia na opory tarcia elementów silnika. Przedstawiono możliwość zastosowania opracowanej wcześniej dla tarcia granicznego zależności do ilościowego opisu zmian lepkości oleju na skutek zmian temperatury i ciśnienia. Wskazano, że zastosowanie tej zależności umożliwi lepsze sterowanie własnościami reologicznymi olejów silnikowych, tak aby uzyskać w możliwie szerokim zakresie warunków pracy silników najmniejsze straty energii na pokonywanie oporów tarcia elementów silnika, a w konsekwencji zredukować zużycie paliwa i idącą za tym emisję CO2 do powietrza atmosferycznego

    General-relativistic rotation: self-gravitating fluid tori in motion around black holes

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    We obtain from the first principles a general-relativistic Keplerian rotation law for self-gravitating disks around spinning black holes. This is an extension of a former rotation law that was designed mainly for toroids around spin-less black holes. We integrate numerically axial stationary Einstein equations with self-gravitating disks around spinless or spinning black holes; that includes the first ever integration of the Keplerian selfgravitating tori. This construction can be used for the description of tight black hole-torus systems produced during coalescences of two neutron stars or modelling of compact active galactic nuclei.Comment: Matches published versio

    Spectral properties of the Cauchy process

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    We study the spectral properties of the transition semigroup of the killed one-dimensional Cauchy process on the half-line (0,infty) and the interval (-1,1). This process is related to the square root of one-dimensional Laplacian A = -sqrt(-d^2/dx^2) with a Dirichlet exterior condition (on a complement of a domain), and to a mixed Steklov problem in the half-plane. For the half-line, an explicit formula for generalized eigenfunctions psi_lambda of A is derived, and then used to construct spectral representation of A. Explicit formulas for the transition density of the killed Cauchy process in the half-line (or the heat kernel of A in (0,infty)), and for the distribution of the first exit time from the half-line follow. The formula for psi_lambda is also used to construct approximations to eigenfunctions of A in the interval. For the eigenvalues lambda_n of A in the interval the asymptotic formula lambda_n = n pi/2 - pi/8 + O(1/n) is derived, and all eigenvalues lambda_n are proved to be simple. Finally, efficient numerical methods of estimation of eigenvalues lambda_n are applied to obtain lower and upper numerical bounds for the first few eigenvalues up to 9th decimal point.Comment: 37 pages, 1 figur

    Wpływ emisji energii dźwiękowej ze szlaków komunikacyjnych i innych miejsc konsumpcji energii na zdrowie ludzi

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    This article aims to draw attention to the hitherto unexplored and scarcely noticed the problem of the effects of the consumption of increasing amounts of energy to human health and ecosystems exposed to emissions processed in the phase of energy consumption. Ever-increasing amounts of energy are consumed in relatively small areas of highways. Reference is made to the results of pioneering research on the impact of emitted sound energy by transport routes and by industrial noise on human health (Borzyszkowski 2010). This was clearly found to increase in people exposed to prolonged acoustic wave energy. The results of the effect of noise on human health clearly indicate the need for further research in this field. It should be emphasized that although the research and evaluation conducted by the Institute for Environmental Protection and Proeko CDM Ltd., which have been presented in this article, are pioneering and include an analysis of the cause-and-effect phenomenon, they do not, however, indicate the mechanism of the effect of noise on human health. The category rating of disease symptoms caused by the noise indicates that the key to clarifying the influence of the energy supplied to the organisms of people on the way of acoustic waves on their health may be forced supplied energy changes of biochemical reactions occurring in humans

    Aflatoxin levels, plasma vitamins A and E concentrations, and their association with HIV and hepatitis B virus infections in Ghanaians: a cross-sectional study

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    <p>Abstract</p> <p>Background</p> <p>Micronutrient deficiencies occur commonly in people infected with the human immunodeficiency virus. Since aflatoxin exposure also results in reduced levels of several micronutrients, HIV and aflatoxin may work synergistically to increase micronutrient deficiencies. However, there has been no report on the association between aflatoxin exposure and micronutrient deficiencies in HIV-infected people. We measured aflatoxin B<sub>1 </sub>albumin (AF-ALB) adduct levels and vitamins A and E concentrations in the plasma of HIV-positive and HIV-negative Ghanaians and examined the association of vitamins A and E with HIV status, aflatoxin levels and hepatitis B virus (HBV) infection.</p> <p>Methods</p> <p>A cross-sectional study was conducted in which participants completed a demographic survey and gave a 20 mL blood sample for analysis of AF-ALB levels, vitamins A and E concentrations, CD4 counts, HIV viral load and HBV infection.</p> <p>Results</p> <p>HIV-infected participants had significantly higher AF-ALB levels (median for HIV-positive and HIV-negative participants was 0.93 and 0.80 pmol/mg albumin, respectively; p <0.01) and significantly lower levels of vitamin A (-16.94 μg/dL; p <0.0001) and vitamin E (-0.22 mg/dL; p <0.001). For the total study group, higher AF-ALB was associated with significantly lower vitamin A (-4.83 μg/dL for every 0.1 pmol/mg increase in AF-ALB). HBV-infected people had significantly lower vitamin A (-5.66 μg/dL; p = 0.01). Vitamins A and E levels were inversely associated with HIV viral load (p = 0.02 for each), and low vitamin E was associated with lower CD4 counts (p = 0.004).</p> <p>Conclusions</p> <p>Our finding of the significant decrease in vitamin A associated with AF-ALB suggests that aflatoxin exposure significantly compromises the micronutrient status of people who are already facing overwhelming health problems, including HIV infection.</p
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