Heavy-to-light decays with a two-loop accuracy

We present a determination of a new class of three-loop Feynman diagrams describing heavy-to-light transitions. We apply it to find the O(alpha_s^2) corrections to the top quark decay t -> bW and to the distribution of lepton invariant mass in the semileptonic b quark decay b -> ul\nu. We also confirm the previously determined total rate of that process as well as the O(alpha^2) corrections to the muon lifetime.Comment: 5 page

Pion pole contribution to hadronic light-by-light scattering and muon anomalous magnetic moment

We derive an analytic result for the pion pole contribution to the light-by-light scattering correction to the anomalous magnetic moment of the muon, $a_\mu = (g_\mu-2)/2$. Using the vector meson dominance model (VMD) for the pion transition form factor, we obtain $a_\mu^{{\rm LBL},\pi^0} = +56 \times 10^{-11}$.Comment: 4 pages, revte

Expansion of bound state energies in powers of m/M and (1-m/M)

Elaborating on a previous letter, we use a new approach to compute energy levels of a non-relativistic bound-state of two constituents, with masses m and M, by systematic expansions - one in powers of m/M and another in powers of (1-m/M). Technical aspects of the calculations are described in detail. Theoretical predictions are given for O(alpha(Z*alpha)^5) radiative recoil and O((Z*alpha)^6) pure recoil corrections to the average energy shift and hyperfine splitting relevant for hydrogen, muonic hydrogen, and muonium.Comment: 9 pages, revte

Multi-site genetic analysis of diffusion images and voxelwise heritability analysis : a pilot project of the ENIGMA–DTI working group

The ENIGMA (Enhancing NeuroImaging Genetics through Meta-Analysis) Consortium was set up to analyze brain measures and genotypes from multiple sites across the world to improve the power to detect genetic variants that influence the brain. Diffusion tensor imaging (DTI) yields quantitative measures sensitive to brain development and degeneration, and some common genetic variants may be associated with white matter integrity or connectivity. DTI measures, such as the fractional anisotropy (FA) of water diffusion, may be useful for identifying genetic variants that influence brain microstructure. However, genome-wide association studies (GWAS) require large populations to obtain sufficient power to detect and replicate significant effects, motivating a multi-site consortium effort. As part of an ENIGMA–DTI working group, we analyzed high-resolution FA images from multiple imaging sites across North America, Australia, and Europe, to address the challenge of harmonizing imaging data collected at multiple sites. Four hundred images of healthy adults aged 18–85 from four sites were used to create a template and corresponding skeletonized FA image as a common reference space. Using twin and pedigree samples of different ethnicities, we used our common template to evaluate the heritability of tract-derived FA measures. We show that our template is reliable for integrating multiple datasets by combining results through meta-analysis and unifying the data through exploratory mega-analyses. Our results may help prioritize regions of the FA map that are consistently influenced by additive genetic factors for future genetic discovery studies. Protocols and templates are publicly available at (http://enigma.loni.ucla.edu/ongoing/dti-working-group/)

Can we increase students’ scientific literacy while minimizing disciplinary content in a multidisciplinary science course?

Interdisciplinary Studies (IDS) 137 is a multidisciplinary science laboratory course designed for non-science majors at our campus. An overarching objective of the course is to increase scientific problem solving skills and attitudes among the students by having them practice science by completing experiments rather than study discipline-specific course content. Three instructors have worked together to organize the course such that students complete four labs in each of biology, chemistry and physics. To quantitatively measure gains in scientific literacy of IDS 137 students, we developed the Augustana Interdisciplinary Scientific Literacy Evaluation (AISLE). The AISLE includes twenty multiple-choice questions that students complete at the beginning and again at the end of the course. Questions are designed to probe students’ scientific thinking and attitudes in a multidisciplinary manner. The answers are scored using a scale of 2, 1 or 0 for best, acceptable and least correct answers and generates a numeric score that corresponds to scientific skills and attitudes. I will outline the instructional strategy we used to design the course and the criteria we selected to develop the AISLE such that it would reliably measure gains in scientific literacy among the enrolled students. The validity of AISLE was established by collecting calibration data from undergraduate students in non-science majors, from science majors at various stages of their degree and from professors. I will invite the audience to investigate samples of the AISLE problems and test their scientific literacy first hand to evaluate how effectively our approach probes scientific skills and attitudes. I will conclude by presenting the calibration data and compare it to data we have collected from IDS 137 students from two academic years

Heritability of head motion during resting state functional MRI in 462 healthy twins

Head motion (HM) is a critical confounding factor in functional MRI. Here we investigate whether HM during resting state functional MRI (RS-fMRI) is influenced by genetic factors in a sample of 462 twins (65% fema≤ 101 MZ (monozygotic) and 130 DZ (dizygotic) twin pairs; mean age: 21 (SD=3.16), range 16-29). Heritability estimates for three HM components-mean translation (MT), maximum translation (MAXT) and mean rotation (MR)-ranged from 37 to 51%. We detected a significant common genetic influence on HM variability, with about two-thirds (genetic correlations range 0.76-1.00) of the variance shared between MR, MT and MAXT. A composite metric (HM-PC1), which aggregated these three, was also moderately heritable (h2=42%). Using a sub-sample (N=35) of the twins we confirmed that mean and maximum translational and rotational motions were consistent "traits" over repeated scans (r=0.53-0.59); reliability was even higher for the composite metric (r=0.66). In addition, phenotypic and cross-trait cross-twin correlations between HM and resting state functional connectivities (RS-FCs) with Brodmann areas (BA) 44 and 45, in which RS-FCs were found to be moderately heritable (BA44: h2-=0.23 (sd=0.041), BA45: h2-=0.26 (sd=0.061)), indicated that HM might not represent a major bias in genetic studies using FCs. Even so, the HM effect on FC was not completely eliminated after regression. HM may be a valuable endophenotype whose relationship with brain disorders remains to be elucidated

Genome-wide association study of working memory brain activation

Highlights - We used voxel-level BOLD heritability to define region-of-interest phenotypes. - We performed genome-wide association on 20 n-back functional MRI BOLD phenotypes. - A BANK1 SNP explained 5.5% of variance in supramarginal gyrus n-back BOLD signal. - 31 independent SNPs were associated with BOLD signal change at p −5. Abstract In a population-based genome-wide association (GWA) study of n-back working memory task-related brain activation, we extracted the average percent BOLD signal change (2-back minus 0-back) from 46 regions-of-interest (ROIs) in functional MRI scans from 863 healthy twins and siblings. ROIs were obtained by creating spheres around group random effects analysis local maxima, and by thresholding a voxel-based heritability map of working memory brain activation at 50%. Quality control for test-retest reliability and heritability of ROI measures yielded 20 reliable (r > 0.7) and heritable (h2 > 20%) ROIs. For GWA analysis, the cohort was divided into a discovery (n = 679) and replication (n = 97) sample. No variants survived the stringent multiple-testing-corrected genome-wide significance threshold (p −9), or were replicated (p −5. Two SNPs (rs7917410 and rs7672408) were associated at a significance level of p −7. Only one, most strongly affecting BOLD signal change in the left supramarginal gyrus (R2 = 5.5%), had multiple SNPs associated at p −5 in linkage disequilibrium with it, all located in and around the BANK1 gene. BANK1 encodes a B-cell-specific scaffold protein and has been shown to negatively regulate CD40-mediated AKT activation. AKT is part of the dopamine-signaling pathway, suggesting a mechanism for the involvement of BANK1 in the BOLD response to working memory. Variants identified here may be relevant to (the susceptibility to) common disorders affecting brain function