258 research outputs found

    Lunar surface roughness comminution study Final report, 20 Jul. 1964 - 7 Apr. 1965

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    Lunar surface roughness comminution estimated by considering meteoric body catering proces

    The homeobox gene Hex is required in definitive endodermal tissues for normal forebrain, liver and thyroid formation

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    The homeobox gene Hex is expressed in the anterior visceral endoderm (AVE) and rostral definitive endoderm of early mouse embryos. Later, Hex transcripts are detected in liver, thyroid and endothelial precursor cells. A null mutation was introduced into the Hex locus by homologous recombination in embryonic stem cells. Hex mutant embryos exhibit varying degrees of anterior truncation as well as liver and thyroid dysplasia. The liver diverticulum is formed but migration of hepatocytes into the septum transversum fails to occur. Development of the thyroid is arrested at the thyroid bud stage at 9.5 dpc. Brain defects are restricted to the rostral forebrain and have a caudal limit at the zona limitans intrathalamica, the boundary between dorsal and ventral thalamus. Analysis of Hex(−/−) mutants at early stages shows that the prospective forebrain ectoderm is correctly induced and patterned at 7.5 days post coitum (dpc), but subsequently fails to develop. AVE markers are expressed and correctly positioned but development of rostral definitive endoderm is greatly disturbed in Hex(−/−) embryos. Chimeric embryos composed of Hex(−/−) cells developing within a wild-type visceral endoderm show forebrain defects indicating that Hex is required in the definitive endoderm. All together, these results demonstrate that Hex function is essential in definitive endoderm for normal development of the forebrain, liver and thyroid gland

    Bulge Formation by the Coalescence of Giant Clumps in Primordial Disk Galaxies

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    Gas-rich disks in the early universe are highly turbulent and have giant star-forming clumps. Models suggest the clumps form by gravitational instabilities, and if they resist disruption by star formation, then they interact, lose angular momentum, and migrate to the center to form a bulge. Here we study the properties of the bulges formed by this mechanism. They are all thick, slowly rotating, and have a high Sersic index, like classical bulges. Their rapid formation should also give them relatively high alpha-element abundances. We consider fourteen low-resolution models and four high-resolution models, three of which have supernova feedback. All models have an active halo, stellar disk, and gaseous disk, three of the models have a pre-existing bulge and three others have a cuspy dark matter halo. All show the same basic result except the one with the highest feedback, in which the clumps are quickly destroyed and the disk thickens too much. The coalescence of massive disk clumps in the center of a galaxy is like a major merger in terms of orbital mixing. It differs by leaving a bulge with no specific dark matter component, unlike the merger of individual galaxies. Normal supernova feedback has little effect because the high turbulent speed in the gas produces tightly bound clumps. A variety of indirect observations support the model, including clumpy disks with young bulges at high redshift and bulges with relatively little dark matter.Comment: 21 pages, 9 figures, ApJ 688, November 20 2008, in pres

    Ocular Shock Front in the Colliding Galaxy IC 2163

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    The final, definitive version of this paper has been published in The Astrophysical Journal, 831:161 (13pp), 2016 November 4, doi:10.3847/0004-637X/831/2/161 © 2016. The American Astronomical Society. All rights reserved.ALMA observations in the CO 1 - 0 line of the interacting galaxies IC 2163 and NGC 2207 at 2" x 1.5" resolution reveal how the encounter drives gas to pile up in narrow, ~ 1 kpc wide, "eyelids" in IC 2163. IC 2163 and NGC 2207 are involved in a grazing encounter, which has led to development in IC 2163 of an eye-shaped (ocular) structure at mid-radius and two tidal arms. The CO data show that there are large velocity gradients across the width of each eyelid, with a mixture of radial and azimuthal streaming of gas at the outer edge of the eyelid relative to its inner edge. The sense of the radial streaming in the eyelids is consistent with the idea that gas from the outer part of IC 2163 flows inward until its radial streaming slows down abruptly and the gas piles up in the eyelids. The radial compression at the eyelids causes an increase in the gas column density by direct radial impact and also leads to a high rate of shear. We find a strong correlation between the molecular column densities and the magnitude of dv/dR across the width of the eyelid at fixed values of azimuth. Substantial portions of the eyelids have high velocity dispersion in CO, indicative of elevated turbulence there.Peer reviewedFinal Accepted Versio

    Criminal and Noncriminal Psychopathy: The Devil is in the Detail

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    Brooks, NS ORCiD: 0000-0003-1784-099XPsychopathy is prevalent and problematic in criminal populations, but is also found to be present in noncriminal populations. In 1992, Robert Hare declared that psychopaths may also “be found in the boardroom”, which has since been followed by an interest in the issue of noncriminal, or even successful, psychopathy. In this chapter, the paradox of criminal and noncriminal psychopathy is discussed with specific attention given to the similarities and differences that account for psychopathic personality across contexts. That psychopathy is a condition typified by a constellation of traits and behaviours requires wider research across diverse populations, and thus the streams of research related to criminal and noncriminal psychopathy are presented and the implications of these contrasting streams are explored

    Design, development and validity testing of the Gang Affiliation Risk Measure (GARM)

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    This study aimed to create a measure of risk for gang affiliation, for use in the UK. A pilot stage invited gang affiliated and non-gang affiliated participants between the ages of 16–25 years to retrospectively self-report on 58 items of risk exposure at the age of 11 years. Based on performance of these items, a 26-item measure was developed and administered to a main study sample (n=185) of gang affiliated and non-gang affiliated participants. Categorical Principal Component Analysis was applied to data, yielding a single-factor solution (historic lack of safety and current perception of threat). A 15-item gang affiliation risk measure (GARM) was subsequently created. The GARM demonstrated good internal consistency, construct validity and discriminative ability. Items from the GARM were then transformed to read prospectively, resulting in a test measure for predictive purposes (T-GARM). The T-GARM requires further validation regarding its predictive utility and generalisability. However, this study has resulted in the first measure of gang affiliation, with promising results

    Reliability and validity of the Psychopathy Checklist-Revised in the assessment of risk for institutional violence: A cautionary note on DeMatteo et al. (2020).

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    A group of 12 authors (GA) shared a statement of concern (SoC) warning against the use of the Hare Psychopathy Checklist-Revised (PCL-R; Hare, 1991, 2003) to assess risk for serious institutional violence in US capital sentencing cases (DeMatteo et al., 2020). Notably, the SoC was not confined to capital sentencing issues, but included institutional violence in general. Central to the arguments presented in the SoC was that the PCL-R has poor predictive validity for institutional violence and also inadequate field reliability. The GA also identified important issues about the fallibility and inappropriate use of any clinical/forensic assessments, questionable evaluator qualifications, and their effects on capital sentencing decisions. However, as a group of forensic academics, researchers, and clinicians, we are concerned that the PCL-R represents a psycholegal red herring, while the SoC did not address critical legislative, systemic, and evaluator/rating issues that affect all risk assessment tools. We contend that the SoC’s literature review was selective and that the resultant opinions about potential uses and misuses of the PCL-R were ultimately misleading. We focus our response on the evidence and conclusions proffered by the GA concerning the use of the PCL-R in capital and other cases. We provide new empirical findings regarding the PCL-R’s predictive validity and field reliability to further demonstrate its relevance for institutional violence risk assessment and management. We further demonstrate why the argument that group data cannot be relevant for single-case assessments is erroneous. Recommendations to support the ethical and appropriate use of the PCL-R for risk assessment are provided

    High star formation rates in turbulent atomic-dominated gas in the interacting galaxies IC 2163 and NGC 2207

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    This is a pre-copyedited, author produced PDF of an article accepted for publication in The Astrophysical Journal following peer review. The version of record (The Astrophysical Journal, 823:26, 2016 May 18) is available on line at doi:10.3847/0004-637X/823/1/26 © 2016. The American Astronomical Society. All rights reserved.CO observations of the interacting galaxies IC 2163 and NGC 2207 are combined with HI, Halpha and 24 microns to study the star formation rate (SFR) surface density as a function of the gas surface density. More than half of the high SFR regions are HI dominated. When compared to other galaxies, these HI-dominated regions have excess SFRs relative to their molecular gas surface densities but normal SFRs relative to their total gas surface densities. The HI-dominated regions are mostly located in the outer part of NGC 2207, where the HI velocity dispersion is high, 40 - 50 km/s. We suggest that the star-forming clouds in these regions have envelopes at lower densities than normal, making them predominantly atomic, and cores at higher densities than normal because of the high turbulent Mach numbers. This is consistent with theoretical predictions of a flattening in the density probability distribution function for compressive, high Mach number turbulence.Peer reviewedFinal Accepted Versio
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