The Stroop Color Word test and learning disabilities

This Thesis study critically explored the feasibility of utilizing the Stroop Color Word test as a psychological instrument to aid in the determination of learning disabilities (LD) in children aged nine to sixteen years old. Children with a previous diagnosis of LD were sought out for the experimental group by participating graduate students and, when confirmed by personal administration of intelligence and achievement tests, were administered a battery of nine neuropsychological instruments. A comparison was made with a control group of children with the same age and geographical background on the four different Stroop variables: the Word, Color, Color-Word, and Interference variables. Two of the four variables proved to be statistically significant between the experimental and control groups: the Word variable and the Color variable. Of the experimental group, the mean scores of three out of four different Stroop variables were lower than those concurrent scores of the control group. This test can be utilized to discriminate between LD and Non-LD groups when comparing the Word and Color Variables

Development of Lithium-Drifted Silicon Detectors and Investigation of Cosmic Antihelium Sensitivity for the GAPS Experiment -- an Indirect Search for Dark Matter

Uncovering the nature of dark matter is one of the most pressing problems in 21st century cosmology. Despite overwhelming evidence that dark matter exists and vigorous experimental efforts to detect it, dark matter has evaded detection and its fundamental nature remains shrouded in mystery. Indirect dark matter detection experiments search for Standard Model byproducts of dark matter annihilation or decay. At low energies, cosmic antideuterons provide an especially clean dark matter signature, since the production of low-energy antideuterons from conventional astrophysical processes is highly suppressed. The General Antiparticle Spectrometer (GAPS) is an Antarctic balloon experiment designed to search for low-energy cosmic antinuclei as signatures of dark matter. GAPS is optimized to detect low-energy antideuterons, as well as to provide unprecedented sensitivity to low-energy antiprotons and antihelium nuclei. GAPS uses a novel approach to detect antinuclei, based on the formation, decay, and annihilation of exotic atoms. At least three GAPS long-duration balloon (LDB) flights are planned, with the first launch date anticipated for December 2022. The core of the GAPS instrument is a particle tracker, comprised of >1000 lithium-drifted silicon (Si(Li)) detectors, that provides particle tracking and X-ray spectroscopy capabilities. In order to preserve the long-term performance of the tracker, the Si(Li) detectors require a surface passivation coating to protect against environmental contamination. In this thesis, I cover four main areas of my research: prototype Si(Li) detector fabrication and performance evaluation; development of a surface passivation technique to ensure the long-term stability of GAPS flight detectors; calculation of the GAPS antihelium sensitivity using particle tracking; and prediction of the antihelium exotic atom X-ray energies and yields for future identification studies. I discuss the prototype fabrication work that was carried out at Columbia, which led to the successful mass-production of large-area Si(Li) detectors for the GAPS LDB flights. I report the research and development of a surface passivation method to protect the GAPS flight detectors from environmental contamination. I then describe the calibration scheme for the GAPS Si(Li) detectors, and a simulation study that I conducted to disentangle the contribution of Compton scattering and intrinsic detector performance on the observed spectra. I then move on to discuss the simulation studies used to determine the performance capabilities of GAPS. I describe the benchmarking of the hadronic annihilation products in antinucleus-nucleus annihilations in Geant4. I review the exotic atom cascade model used to determine the X-rays produced by antiprotonic and antideuteronic exotic atoms, and discuss my work extending this model to describe the de-excitation of antihelium exotic atoms. Finally, I present the first GAPS antihelium nuclei sensitivity study, based on full instrument simulation, event reconstruction, and realistic atmospheric influence simulations

Numerical models of collisions between core-collapse supernovae and circumstellar shells

Recent observations of luminous Type IIn supernovae (SNe) provide compelling evidence that massive circumstellar shells surround their progenitors. In this paper we investigate how the properties of such shells influence the SN lightcurve by conducting numerical simulations of the interaction between an expanding SN and a circumstellar shell ejected a few years prior to core collapse. Our parameter study explores how the emergent luminosity depends on a range of circumstellar shell masses, velocities, geometries, and wind mass-loss rates, as well as variations in the SN mass and energy. We find that the shell mass is the most important parameter, in the sense that higher shell masses (or higher ratios of M_shell/M_SN) lead to higher peak luminosities and higher efficiencies in converting shock energy into visual light. Lower mass shells can also cause high peak luminosities if the shell is slow or if the SN ejecta are very fast, but only for a short time. Sustaining a high luminosity for durations of more than 100 days requires massive circumstellar shells of order 10 M_sun or more. This reaffirms previous comparisons between pre-SN shells and shells produced by giant eruptions of luminous blue variables (LBVs), although the physical mechanism responsible for these outbursts remains uncertain. The lightcurve shape and observed shell velocity can help diagnose the approximate size and density of the circumstellar shell, and it may be possible to distinguish between spherical and bipolar shells with multi-wavelength lightcurves. These models are merely illustrative. One can, of course, achieve even higher luminosities and longer duration light curves from interaction by increasing the explosion energy and shell mass beyond values adopted here.Comment: Accepted for publication in MNRAS. Tables of numerical results (SN lightcurves and velocities) to be published online. (Updated to fix figures

Observed Fractions of Core-Collapse Supernova Types and Initial Masses of their Single and Binary Progenitor Stars

We analyse observed fractions of core-collapse SN types from the Lick Observatory SN Search, and we discuss corresponding implications for massive star evolution. For a standard IMF, observed fractions of SN types cannot be reconciled with expectations of single-star evolution. The mass range of WR stars that shed their H envelopes via their own mass loss accounts for less than half the observed fraction of SNeIbc. Progenitors of SNeIbc must extend to a much lower range of initial masses than classical WR stars, and we argue that most SNIbc and SNIIb progenitors must arise from binary Roche-lobe overflow. SNeIc still trace higher mass and metallicity, because line-driven winds in the WR stage remove the He layer and propel the transition from SNIb to Ic. Less massive progenitors of SNeIb and IIb may not be classical WR stars; they may be underluminous with weak winds, possibly hidden by overluminous mass-gainer companions that appear as B[e] supergiants or related objects having aspherical circumstellar material. The remaining SN types (II-P, II-L, and IIn) are redistributed across the full range of initial mass. We consider direct collapse to black holes without visible SNe, but find this problematic. Major areas of remaining uncertainty are (1) the influence of binary separation, rotation, and metallicity, (2) mass differences in progenitors of SNeIIn compared to SNeII-L and II-P, and (3) SNeIc arising from single stars with eruptive mass loss, its dependence on metallicity, and how it relates to diversity within the SNIc subclass. (abridged)Comment: MNRAS accepted, 18 pages, 8 Figures, 1 color figur

Win-Win for Wind and Wildlife: A Vision to Facilitate Sustainable Development

Wind energy offers the potential to reduce carbon emissions while increasing energy independence and bolstering economic development. However, wind energy has a larger land footprint per Gigawatt (GW) than most other forms of energy production, making appropriate siting and mitigation particularly important. Species that require large unfragmented habitats and those known to avoid vertical structures are particularly at risk from wind development. Developing energy on disturbed lands rather than placing new developments within large and intact habitats would reduce cumulative impacts to wildlife. The U.S. Department of Energy estimates that it will take 241 GW of terrestrial based wind development on approximately 5 million hectares to reach 20% electricity production for the U.S. by 2030. We estimate there are ∼7,700 GW of potential wind energy available across the U.S., with ∼3,500 GW on disturbed lands. In addition, a disturbance-focused development strategy would avert the development of ∼2.3 million hectares of undisturbed lands while generating the same amount of energy as development based solely on maximizing wind potential. Wind subsidies targeted at favoring low-impact developments and creating avoidance and mitigation requirements that raise the costs for projects impacting sensitive lands could improve public value for both wind energy and biodiversity conservation

Copy Number Variations Associated With Obesity‐Related Traits in African Americans: A Joint Analysis Between GENOA and HyperGEN

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95398/1/oby.2012.162.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/95398/2/oby_2790_sm_oby2012162_coi.pd

Genome-wide joint SNP and CNV analysis of aortic root diameter in African Americans: the HyperGEN study

<p>Abstract</p> <p>Background</p> <p>Aortic root diameter is a clinically relevant trait due to its known relationship with the pathogenesis of aortic regurgitation and risk for aortic dissection. African Americans are an understudied population despite a particularly high burden of cardiovascular diseases. We report a genome-wide association study on aortic root diameter among African Americans enrolled in the HyperGEN study. We invoked a two-stage, mixed model procedure to jointly identify SNP allele and copy number variation effects.</p> <p>Results</p> <p>Results suggest novel genetic contributors along a large region between the <it>CRCP </it>and <it>KCTD7 </it>genes on chromosome 7 (p = 4.26 × 10^<b>-7</b>); and the <it>SIRPA </it>and <it>PDYN </it>genes on chromosome 20 (p = 3.28 × 10^<b>-8</b>).</p> <p>Conclusions</p> <p>The regions we discovered are candidates for future studies on cardiovascular outcomes, particularly in African Americans. The methods we employed can also provide an outline for genetic researchers interested in jointly testing SNP and CNV effects and/or applying mixed model procedures on a genome-wide scale.</p

LSST Science Book, Version 2.0

A survey that can cover the sky in optical bands over wide fields to faint magnitudes with a fast cadence will enable many of the exciting science opportunities of the next decade. The Large Synoptic Survey Telescope (LSST) will have an effective aperture of 6.7 meters and an imaging camera with field of view of 9.6 deg^2, and will be devoted to a ten-year imaging survey over 20,000 deg^2 south of +15 deg. Each pointing will be imaged 2000 times with fifteen second exposures in six broad bands from 0.35 to 1.1 microns, to a total point-source depth of r~27.5. The LSST Science Book describes the basic parameters of the LSST hardware, software, and observing plans. The book discusses educational and outreach opportunities, then goes on to describe a broad range of science that LSST will revolutionize: mapping the inner and outer Solar System, stellar populations in the Milky Way and nearby galaxies, the structure of the Milky Way disk and halo and other objects in the Local Volume, transient and variable objects both at low and high redshift, and the properties of normal and active galaxies at low and high redshift. It then turns to far-field cosmological topics, exploring properties of supernovae to z~1, strong and weak lensing, the large-scale distribution of galaxies and baryon oscillations, and how these different probes may be combined to constrain cosmological models and the physics of dark energy.Comment: 596 pages. Also available at full resolution at http://www.lsst.org/lsst/sciboo

Mosaic Chromosomal alterations in Blood across ancestries Using Whole-Genome Sequencing

Megabase-scale mosaic chromosomal alterations (mCAs) in blood are prognostic markers for a host of human diseases. Here, to gain a better understanding of mCA rates in genetically diverse populations, we analyzed whole-genome sequencing data from 67,390 individuals from the National Heart, Lung, and Blood Institute Trans-Omics for Precision Medicine program. We observed higher sensitivity with whole-genome sequencing data, compared with array-based data, in uncovering mCAs at low mutant cell fractions and found that individuals of European ancestry have the highest rates of autosomal mCAs and the lowest rates of chromosome X mCAs, compared with individuals of African or Hispanic ancestry. Although further studies in diverse populations will be needed to replicate our findings, we report three loci associated with loss of chromosome X, associations between autosomal mCAs and rare variants in DCPS, ADM17, PPP1R16B and TET2 and ancestry-specific variants in ATM and MPL with mCAs in cis