154 research outputs found

    Evaluating Within-Person Change In Implicit Measures Of Alcohol Associations: Increases In Alcohol Associations Predict Increases In Drinking Risk And Vice Versa

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    Aims: Implicit measures of alcohol associations (i.e. measures designed to assess associations that are fast/reflexive/impulsive) have received substantial research attention. Alcohol associations related to the self (drinking identity), the effects of alcohol (alcohol excite) and appetitive inclinations (alcohol approach) have been found to predict drinking cross-sectionally and over time. A critical next step in this line of research and the goal of this study is to evaluate whether increases in the strength of these associations predict increases in drinking and vice versa. These hypotheses were tested in a sample of first- and second-year US university students: a sample selected because this time period is associated with initiation and escalation of drinking, peak levels of alcohol consumption and severe alcohol-related negative consequences. Short summary: This study's purpose was to evaluate whether increases in the strength of alcohol associations with the self (drinking identity), excitement (alcohol excite) and approach (alcohol approach) as assessed by implicit measures predicted subsequent increases in drinking risk and vice versa using a longitudinal, university student sample. Results were consistent with hypotheses. Methods: A sample of 506 students' (57% women) alcohol associations and alcohol consumption were assessed every 3 months over a 2-year period. Participants' consumption was converted to risk categories based on NIAAA's criteria: non-drinkers, low-risk drinkers and high-risk drinkers. A series of cross-lagged panel models tested whether changes in alcohol associations predicted subsequent change in drinking risk (and vice versa). Results: Across all three measures of alcohol associations, increases in the strength of alcohol associations were associated with subsequent increases in drinking risk and vice versa. Conclusion: Results from this study indicate bi-directional relationships between increases in alcohol associations (drinking identity, alcohol excite and alcohol approach) and subsequent increases in drinking risk. Intervention and prevention efforts may benefit from targeting these associations

    Finite nuclear size and Lamb shift of p-wave atomic states

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    We consider corrections to the Lamb shift of p-wave atomic states due to the finite nuclear size (FNS). In other words, these are radiative corrections to the atomic isotop shift related to FNS. It is shown that the structure of the corrections is qualitatively different from that for s-wave states. The perturbation theory expansion for the relative correction for a p1/2p_{1/2}-state starts from αln(1/Zα)\alpha\ln(1/Z\alpha)-term, while for s1/2s_{1/2}-states it starts from Zα2Z\alpha^2 term. Here α\alpha is the fine structure constant and ZZ is the nuclear charge. In the present work we calculate the α\alpha-terms for 2p2p-states, the result for 2p1/22p_{1/2}-state reads (8α/9π)[ln(1/(Zα)2)+0.710](8\alpha/9\pi)[\ln(1/(Z\alpha)^2)+0.710]. Even more interesting are p3/2p_{3/2}-states. In this case the ``correction'' is by several orders of magnitude larger than the ``leading'' FNS shift.Comment: 4 pages, 2 figure

    Evaluation of the two-photon exchange diagrams for the (1s)22p3/2(1s)^2 2p_{3/2} electron configuration in Li-like ions

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    We present ab initio calculations of the complete gauge-invariant set of two-photon exchange graphs for the (1s)22p3/2(1s)^2 2p_{3/2} electron configuration in Li-like ions. These calculations are an important step towards the precise theoretical determination of the 2p3/22p_{3/2}-2s2s transition energy in the framework of QED.Comment: 17 pages, 6 figure

    Finite nuclear size effect on Lamb shift of s1/2, p1/2, and p3/2 atomic states

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    We consider one-loop self-energy and vacuum polarization radiative corrections to the shift of atomic energy level due to finite nuclear size. Analytic expressions for vacuum polarization corrections are derived. For the self-energy of p1/2 and p3/2 states in addition to already known terms we derive next-to-leading nonlogarithmic Z\alpha-terms. Together with contributions obtained earlier the terms derived in the present work give explicit analytic expressions for s1/2 and p1/2 corrections which agree with results of previous numerical calculations up to Z=100 (Z is the nuclear charge number). We also show that the finite nuclear size radiative correction for a p3/2 state is not small compared to the similar correction for a p1/2 state at least for small Z.Comment: 12 pages, 7 figure

    Image resonance in the many-body density of states at a metal surface

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    The electronic properties of a semi-infinite metal surface without a bulk gap are studied by a formalism that is able to account for the continuous spectrum of the system. The density of states at the surface is calculated within the GW approximation of many-body perturbation theory. We demonstrate the presence of an unoccupied surface resonance peaked at the position of the first image state. The resonance encompasses the whole Rydberg series of image states and cannot be resolved into individual peaks. Its origin is the shift in spectral weight when many-body correlation effects are taken into account

    Genome-wide enrichment analysis between endometriosis and obesity-related traits reveals novel susceptibility loci

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    Endometriosis is a chronic inflammatory condition in women that results in pelvic pain and subfertility, and has been associated with decreased body mass index (BMI). Genetic variants contributing to the heritable component have started to emerge from genome-wide association studies (GWAS), although the majority remain unknown. Unexpectedly, we observed an intergenic locus on 7p15.2 that was genome-wide significantly associated with both endometriosis and fat distribution (waist-to-hip ratio adjusted for BMI; WHRadjBMI) in an independent meta-GWAS of European ancestry individuals. This led us to investigate the potential overlap in genetic variants underlying the aetiology of endometriosis, WHRadjBMI and BMI using GWAS data. Our analyses demonstrated significant enrichment of common variants between fat distribution and endometriosis (P = 3.7 × 10(-3)), which was stronger when we restricted the investigation to more severe (Stage B) cases (P = 4.5 × 10(-4)). However, no genetic enrichment was observed between endometriosis and BMI (P = 0.79). In addition to 7p15.2, we identify four more variants with statistically significant evidence of involvement in both endometriosis and WHRadjBMI (in/near KIFAP3, CAB39L, WNT4, GRB14); two of these, KIFAP3 and CAB39L, are novel associations for both traits. KIFAP3, WNT4 and 7p15.2 are associated with the WNT signalling pathway; formal pathway analysis confirmed a statistically significant (P = 6.41 × 10(-4)) overrepresentation of shared associations in developmental processes/WNT signalling between the two traits. Our results demonstrate an example of potential biological pleiotropy that was hitherto unknown, and represent an opportunity for functional follow-up of loci and further cross-phenotype comparisons to assess how fat distribution and endometriosis pathogenesis research fields can inform each other

    Observation of Orbitally Excited B_s Mesons

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    We report the first observation of two narrow resonances consistent with states of orbitally excited (L=1) B_s mesons using 1 fb^{-1} of ppbar collisions at sqrt{s} = 1.96 TeV collected with the CDF II detector at the Fermilab Tevatron. We use two-body decays into K^- and B^+ mesons reconstructed as B^+ \to J/\psi K^+, J/\psi \to \mu^+ \mu^- or B^+ \to \bar{D}^0 \pi^+, \bar{D}^0 \to K^+ \pi^-. We deduce the masses of the two states to be m(B_{s1}) = 5829.4 +- 0.7 MeV/c^2 and m(B_{s2}^*) = 5839.7 +- 0.7 MeV/c^2.Comment: Version accepted and published by Phys. Rev. Let

    Common variants near MC4R are associated with fat mass, weight and risk of obesity.

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    To identify common variants influencing body mass index (BMI), we analyzed genome-wide association data from 16,876 individuals of European descent. After previously reported variants in FTO, the strongest association signal (rs17782313, P = 2.9 x 10(-6)) mapped 188 kb downstream of MC4R (melanocortin-4 receptor), mutations of which are the leading cause of monogenic severe childhood-onset obesity. We confirmed the BMI association in 60,352 adults (per-allele effect = 0.05 Z-score units; P = 2.8 x 10(-15)) and 5,988 children aged 7-11 (0.13 Z-score units; P = 1.5 x 10(-8)). In case-control analyses (n = 10,583), the odds for severe childhood obesity reached 1.30 (P = 8.0 x 10(-11)). Furthermore, we observed overtransmission of the risk allele to obese offspring in 660 families (P (pedigree disequilibrium test average; PDT-avg) = 2.4 x 10(-4)). The SNP location and patterns of phenotypic associations are consistent with effects mediated through altered MC4R function. Our findings establish that common variants near MC4R influence fat mass, weight and obesity risk at the population level and reinforce the need for large-scale data integration to identify variants influencing continuous biomedical traits

    Search for three-nucleon short-range correlations in light nuclei

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    We present new data probing short-range correlations (SRCs) in nuclei through the measurement of electron scattering off high-momentum nucleons in nuclei. The inclusive ^{4}He/^{3}He cross section ratio is observed to be both x and Q^{2} independent for 1.52, our data support the hypothesis that a previous claim of three-nucleon correlation dominance was an artifact caused by the limited resolution of the measurement. While 3N-SRCs appear to have an important contribution, our data show that isolating 3N-SRCs is significantly more complicated than for 2N-SRCs.United States. Department of Energy (Contract DE-AC05-06OR23177)United States. Department of Energy (Contract DE-AC02-06CH11357)United States. Department of Energy (Contract DE-FG02-96ER40950
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