1,214 research outputs found

    Redshift clustering in the Hubble Deep Field

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    We present initial results from a redshift survey carried out with the Low Resolution Imaging Spectrograph on the 10~m W. M. Keck Telescope in the Hubble Deep Field. In the redshift distribution of the 140 extragalactic objects in this sample we find 6 strong peaks, with velocity dispersions of ∼400{\sim}400{\kms}. The areal density of objects within a particular peak, while it may be non-uniform, does not show evidence for strong central concentration. These peaks have characteristics (velocity dispersions, density enhancements, spacing, and spatial extent) similar to those seen in a comparable redshift survey in a different high galactic latitude field (Cohen et al 1996), confirming that the structures are generic. They are probably the high redshift counterparts of huge galaxy structures (``walls'') observed locally.Comment: 14 pages, including 2 figures, to appear in ApJ Letter

    Caltech Faint Galaxy Redshift Survey X: A Redshift Survey in the Region of the Hubble Deep Field North

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    A redshift survey has been carried out in the region of the Hubble Deep Field North using the Low Resolution Imaging Spectrograph at the Keck Observatory. The resulting redshift catalog, which contains 671 entries, is a compendium of our own data together with published LRIS/Keck data. It is more than 92% complete for objects, irrespective of morphology, to R=24R = 24 mag in the HDF itself and to R=23R = 23 mag in the Flanking Fields within a diameter of 8 arcmin centered on the HDF, an unusually high completion for a magnitude limited survey performed with a large telescope. A median redshift z=1.0z = 1.0 is reached at R∼23.8R \sim 23.8. Strong peaks in the redshift distribution, which arise when a group or poor cluster of galaxies intersect the area surveyed, can be identified to z∼1.2z \sim 1.2 in this dataset. More than 68% of the galaxies are members of these redshift peaks. In a few cases, closely spaced peaks in zz can be resolved into separate groups of galaxies that can be distinguished in both velocity and location on the sky. The radial separation of these peaks in the pencil-beam survey is consistent with a characteristic length scale for the their separation of ≈\approx70 Mpc in our adopted cosmology (h=0.6,ΩM=0.3h = 0.6, \Omega_M = 0.3, Λ=0\Lambda = 0). Strong galaxy clustering is in evidence at all epochs back to z≤1.1z \le 1.1. (abstract abridged)Comment: Accepted to the ApJ. This version contains all the figures and tables. 2 minor typos in table 2b correcte

    Caltech Faint Galaxy Redshift Survey. XI. The Merger Rate to Redshift 1 from Kinematic Pairs

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    The rate of mass accumulation due to galaxy merging depends on the mass, density, and velocity distribution of galaxies in the near neighborhood of a host galaxy. The fractional luminosity in kinematic pairs combines all of these effects in a single estimator that is relatively insensitive to population evolution. Here we use a k-corrected and evolution-compensated volume-limited sample having an R-band absolute magnitude of M^(k,e)_R ≤ -19.8 + 5 log h mag drawing about 300 redshifts from the Caltech Faint Galaxy Redshift Survey and 3000 from the Canadian Network for Observational Cosmology field galaxy survey to measure the rate and redshift evolution of merging. The combined sample has an approximately constant comoving number and luminosity density from redshift 0.1 to 1.1 (Ω_M = 0.2, Ω_Λ = 0.8); hence, any merger evolution will be dominated by correlation and velocity evolution, not density evolution. We identify kinematic pairs with projected separations less than either 50 or 100 h^(-1) kpc and rest-frame velocity differences of less than 1000 km s^(-1). The fractional luminosity in pairs is modeled as f_L(Δv, r_p, M^(k,e)_τ)(1 + z)^(m,L), where [f_L, m_L] are [0.14 ± 0.07, 0 ± 1.4] and [0.37 ± 0.7, 0.1 ± 0.5] for r_p ≤ 50 and 100 h^(-1) kpc, respectively (Ω_M = 0.2, Ω_Λ = 0.8). The value of mL is about 0.6 larger if Λ = 0. To convert these redshift-space statistics to a merger rate, we use the data to derive a conversion factor to a physical space pair density, a merger probability, and a mean in-spiral time. The resulting mass accretion rate per galaxy (M_1, M_2 ≥ 0.2M*) is 0.02 ± 0.01(1 + z)^(0.1±0.5)M* Gyr^(-1). Present-day high-luminosity galaxies therefore have accreted approximately 0.15M* of their mass over the approximately 7 Gyr to redshift 1. Since merging is likely only weakly dependent on the host mass, the fractional effect, δM/M 0.15M*/M, is dramatic for lower mass galaxies but is, on the average, effectively perturbative for galaxies above 1M*

    Evaluation of a complex intervention (Engager) for prisoners with common mental health problems, near to and after release: study protocol for a randomised controlled trial.

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    INTRODUCTION: The 'Engager' programme is a 'through-the-gate' intervention designed to support prisoners with common mental health problems as they transition from prison back into the community. The trial will evaluate the clinical and cost-effectiveness of the Engager intervention. METHODS AND ANALYSIS: The study is a parallel two-group randomised controlled trial with 1:1 individual allocation to either: (a) the Engager intervention plus standard care (intervention group) or (b) standard care alone (control group) across two investigation centres (South West and North West of England). Two hundred and eighty prisoners meeting eligibility criteria will take part. Engager is a person-centred complex intervention delivered by practitioners and aimed at addressing offenders' mental health and social care needs. It comprises one-to-one support for participants prior to release from prison and for up to 20 weeks postrelease. The primary outcome is change in psychological distress measured by the Clinical Outcomes in Routine Evaluation-Outcome Measure at 6 months postrelease. Secondary outcomes include: assessment of subjective met/unmet need, drug and alcohol use, health-related quality of life and well-being-related quality of life measured at 3, 6 and 12 months postrelease; change in objective social domains, drug and alcohol dependence, service utilisation and perceived helpfulness of services and change in psychological constructs related to desistence at 6 and 12 months postrelease; and recidivism at 12 months postrelease. A process evaluation will assess fidelity of intervention delivery, test hypothesised mechanisms of action and look for unintended consequences. An economic evaluation will estimate the cost-effectiveness. ETHICS AND DISSEMINATION: This study has been approved by the Wales Research Ethics Committee 3 (ref: 15/WA/0314) and the National Offender Management Service (ref: 2015-283). Findings will be disseminated to commissioners, clinicians and service users via papers and presentations. TRIAL REGISTRATION NUMBER: ISRCTN11707331; Pre-results

    Near-Native Protein Loop Sampling Using Nonparametric Density Estimation Accommodating Sparcity

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    Unlike the core structural elements of a protein like regular secondary structure, template based modeling (TBM) has difficulty with loop regions due to their variability in sequence and structure as well as the sparse sampling from a limited number of homologous templates. We present a novel, knowledge-based method for loop sampling that leverages homologous torsion angle information to estimate a continuous joint backbone dihedral angle density at each loop position. The φ,ψ distributions are estimated via a Dirichlet process mixture of hidden Markov models (DPM-HMM). Models are quickly generated based on samples from these distributions and were enriched using an end-to-end distance filter. The performance of the DPM-HMM method was evaluated against a diverse test set in a leave-one-out approach. Candidates as low as 0.45 Å RMSD and with a worst case of 3.66 Å were produced. For the canonical loops like the immunoglobulin complementarity-determining regions (mean RMSD <2.0 Å), the DPM-HMM method performs as well or better than the best templates, demonstrating that our automated method recaptures these canonical loops without inclusion of any IgG specific terms or manual intervention. In cases with poor or few good templates (mean RMSD >7.0 Å), this sampling method produces a population of loop structures to around 3.66 Å for loops up to 17 residues. In a direct test of sampling to the Loopy algorithm, our method demonstrates the ability to sample nearer native structures for both the canonical CDRH1 and non-canonical CDRH3 loops. Lastly, in the realistic test conditions of the CASP9 experiment, successful application of DPM-HMM for 90 loops from 45 TBM targets shows the general applicability of our sampling method in loop modeling problem. These results demonstrate that our DPM-HMM produces an advantage by consistently sampling near native loop structure. The software used in this analysis is available for download at http://www.stat.tamu.edu/~dahl/software/cortorgles/

    The role of irritability in the relation between job stressors, emotional reactivity, and counterproductive work behaviour

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    Researchers have stressed the importance of assessing individual differences in personality as an approach to understanding aggressive and deviant conduct across different contexts. This study investigated the moderation role of irritability, a specific aggression-related disposition, in the process of work stressors that are conducive to counterproductive work behaviour (CWB) within the stressor–emotion model. From a total sample of 1147 Italian workers (53.5% women), high- and low-irritability groups were identified. Then, using a multigroup structural equations model, we simultaneously examined all the relations in both high- and low-irritability groups, and investigated whether these relations were different between them. Results showed that job stressors elicited negative emotions that, in turn, lead to CWB. Moreover, some job stressors influenced CWB directly only in the high-irritability group. Overall, irritability moderated the relation among job stressors and CWB but not the relation among job stressors and negative emotions, with the sole exception of role conflict. As well, irritability did not moderate the relation between emotion and CWB. Thus, high-irritability employees may be more prone to react aggressively to job stressors via multiple functioning paths. The principal differences between low- and high-irritability individuals could be how they manage the impact of perceived stressors on emotions and behaviour
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