989 research outputs found

    Biologic effects of oil fly ash.

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    Epidemiologic studies have demonstrated increased human morbidity and mortality with elevations in the concentration of ambient air particulate matter (PM). Fugitive fly ash from the combustion of oil and residual fuel oil significantly contributes to the ambient air particle burden. Residual oil fly ash (ROFA) is remarkable in the capacity to provoke injury in experimental systems. The unique composition of this emission source particle makes it particularly useful as a surrogate for ambient air PM in studies of biologic effects testing the hypothesis that metals mediate the biologic effects of air pollution particles. A majority of the in vitro and animal model investigations support the postulate that transition metals present in ROFA (especially vanadium) participate in Fenton-like chemical reactions to produce reactive oxygen species. This is associated with tyrosine phosphorylation, nuclear factor kappa B and other transcription factor activation, induction of inflammatory mediator expression, and inflammatory lung injury. It is also evident that vanadium accounts for a significant portion of the biologic activity of ROFA. The extrapolation of this body of investigation on ROFA to the field of ambient air PM is difficult, as particles in numerous environments have such small amounts of vanadium

    Second-generation PLINK: rising to the challenge of larger and richer datasets

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    PLINK 1 is a widely used open-source C/C++ toolset for genome-wide association studies (GWAS) and research in population genetics. However, the steady accumulation of data from imputation and whole-genome sequencing studies has exposed a strong need for even faster and more scalable implementations of key functions. In addition, GWAS and population-genetic data now frequently contain probabilistic calls, phase information, and/or multiallelic variants, none of which can be represented by PLINK 1's primary data format. To address these issues, we are developing a second-generation codebase for PLINK. The first major release from this codebase, PLINK 1.9, introduces extensive use of bit-level parallelism, O(sqrt(n))-time/constant-space Hardy-Weinberg equilibrium and Fisher's exact tests, and many other algorithmic improvements. In combination, these changes accelerate most operations by 1-4 orders of magnitude, and allow the program to handle datasets too large to fit in RAM. This will be followed by PLINK 2.0, which will introduce (a) a new data format capable of efficiently representing probabilities, phase, and multiallelic variants, and (b) extensions of many functions to account for the new types of information. The second-generation versions of PLINK will offer dramatic improvements in performance and compatibility. For the first time, users without access to high-end computing resources can perform several essential analyses of the feature-rich and very large genetic datasets coming into use.Comment: 2 figures, 1 additional fil

    Dead Or Alive? The Law, Policy, And Market Effects Of Legislation On Unclaimed Life Insurance Benefits

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    A wave of multi-state audits on the insurance industry’s use of the Social Security Administration’s Death Master File (DMF) stirred national controversy over the status of unclaimed life insurance proceeds. Multi-state investigations uncovered “asymmetric” use of the DMF among many large insurance companies. Accusations of unethical behavior led to numerous settlement agreements between state regulators and insurers. Payouts and fines stemming from these settlements already number in the billions of dollars. Legislative responses are also underway. Some states have adopted—and others are considering—legislation requiring life insurers to search the DMF to identify and pay (or eascheat) unclaimed death benefits. Currently, legislative responses vary among the states, underscoring the longstanding tension between uniformity and state-centric regulation of insurance in the United States. Some states have imposed DMF search requirements on a prospective basis. Others have attempted to apply such requirements on a retroactive basis, affecting both new and existing policies. Emerging legislation on unclaimed life insurance has significant implications for consumers, insurance markets, and even state finances. This Article focuses on the crucial question of retroactive versus prospective applicability of legislation on unclaimed life insurance benefits. In considering the financial implications and legal dimensions of this question, this Article concludes in favor of prospective applicability. Though presumably well intentioned, the downsides of retroactive legislation on unclaimed life insurance benefits outweigh the upsides

    Surface Contact Model for Comets and Asteroids

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    A contact force model was developed for use in touch and go (TAG) surface sampling simulations on small celestial bodies such as comets and asteroids. In TAG scenarios, a spacecraft descending toward the surface of a small body comes into contact with the surface for a short duration of time, collects material samples with a sampler device, and then ascends to leave the surface. The surface contact required 6-DOF (degrees of freedom) dynamics models due to coupling of the attitude and translation dynamics during the contact. The model described here is for contact scenarios that utilize a rotating brush wheel sampler (BWS) to collect surface material. The model includes stiffness and damping of the surface material during BWS vertical motion, lateral friction from the BWS dragging across the surface, and lateral shear from the rotating BWS scooping the surface material. This model is useful for any mission to asteroids or comets that incorporates surface sampling operations

    Sphalerons in Two Higgs Doublet Theories

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    We undertake a comprehensive investigation of the properties of the sphaleron in electroweak theories with two Higgs doublets. We do this in as model-independent a way as possible: by exploring the physical parameter space described by the masses and mixing angles of the Higgs particles. If there is a large split in the masses of the neutral Higgs particles, there can be several sphaleron solutions, distinguished by their properties under parity and the behaviour of the Higgs field at the origin. In general, these solutions appear in parity conjugate pairs and are not spherically symmetric, although the departure from spherical symmetry is small. Including CP violation in the Higgs potential can change the energy of the sphaleron by up to 14 percent for a given set of Higgs masses, with significant implications for the baryogenesis bound on the mass of the lightest Higgs

    Palmitoylation of claudins is required for efficient tight-junction localization

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    Palmitoylation of integral membrane proteins can affect intracellular trafficking, protein-protein interactions and protein stability. The goal of the present study was to determine whether claudins, transmembrane-barrier-forming proteins of the tight junction, are palmitoylated and whether this modification has functional implications for the tight-junction barrier. Claudin-14, like other members of the claudin family, contains membrane-proximal cysteines following both the second and the fourth transmembrane domains, which we speculated could be modified b

    Multisphalerons in the Weinberg-Salam Theory

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    We construct multisphaleron solutions in the Weinberg-Salam theory. The multisphaleron solutions carry Chern-Simons charge n/2n/2, where nn is an integer, counting the winding of the fields in the azimuthal angle. The well-known sphaleron has n=1n=1. The multisphalerons possess axial symmetry and parity reflection symmetry. We vary the Higgs mass and the mixing angle. For small nn the energies of the multisphalerons are on the order of nn times the energy of the sphaleron and their magnetic dipole moments are on the order of nn times the magnetic dipole moment of the sphaleron.Comment: 18 pages, latex, 17 figures in uuencoded postscript files. THU-94/1
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