483 research outputs found

    Clustering at High Redshift: Precise Constraints from a Deep, Wide Area Survey

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    We present constraints on the evolution of large-scale structure from a catalog of 710,000 galaxies with I_AB <= 24 derived from a KPNO 4m CCD imaging survey of a contiguous 4 deg x 4 deg region. The advantage of using large contiguous surveys for measuring clustering properties on even modest angular scales is substantial: the effects of cosmic scatter are strongly suppressed. We provide highly accurate measurements of the two-point angular correlation function, w(theta), as a function of magnitude on scales up to 1.5 degrees. The amplitude of w(theta) declines by a factor of ~10 over the range 16 <= I <= 20 but only by a factor of 2 - 3 over the range 20 < I <= 23. For a redshift dependence of the spatial correlation function, xi(r), parameterized as xi(r,z)=(r/r_o)^(-gamma)(1 + z)^(-[3+epsilon]), we find r_o=5.2 +/- 0.4 Mpc/h, and epsilon >= 0 for I <= 20. This is in good agreement with the results from local redshift surveys. At I > 20, our best fit values shift towards lower r_o and more negative epsilon. A strong covariance between r_o and epsilon prevent us from rejecting epsilon > 0 even at faint magnitudes but if epsilon > 1, we strongly reject r_o <= 4/h Mpc (co-moving). The above expression for xi(r,z) and our data give a correlation length of r_o(z=0.5) approx 3.0 +/- 0.4 Mpc/h, about a factor of 2 larger than the correlation length at z = 0.5 derived from the Canada--France Redshift Survey (CFRS). The small volume sampled by the CFRS and other deep redshift probes, however, make these spatial surveys strongly susceptible to cosmic scatter and will tend to bias their derived correlation lengths low. Our galaxy counts agree well with those from the HDF survey and, thus, argue against a significant inclusion of sub-galactic components in the latter census for I < 24.Comment: 31 pages, including 11 figures. Source file is LaTex. Figures are postscript format. Accepted for publication in the Astrophysical Journa

    Loose Groups of Galaxies in the Las Campanas Redshift Survey

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    A ``friends-of-friends'' percolation algorithm has been used to extract a catalogue of dn/n = 80 density enhancements (groups) from the six slices of the Las Campanas Redshift Survey (LCRS). The full catalogue contains 1495 groups and includes 35% of the LCRS galaxy sample. A clean sample of 394 groups has been derived by culling groups from the full sample which either are too close to a slice edge, have a crossing time greater than a Hubble time, have a corrected velocity dispersion of zero, or contain a 55-arcsec ``orphan'' (a galaxy with a mock redshift which was excluded from the original LCRS redshift catalogue due to its proximity to another galaxy -- i.e., within 55 arcsec). Median properties derived from the clean sample include: line-of-sight velocity dispersion sigma_los = 164km/s, crossing time t_cr = 0.10/H_0, harmonic radius R_h = 0.58/h Mpc, pairwise separation R_p = 0.64/h Mpc, virial mass M_vir = (1.90x10^13)/h M_sun, total group R-band luminosity L_tot = (1.30x10^11)/h^2 L_sun, and R-band mass-to-light ratio M/L = 171h M_sun/L_sun; the median number of observed members in a group is 3.Comment: 32 pages of text, 27 figures, 7 tables. Figures 1, 4, 6, 7, and 8 are in gif format. Tables 1 and 3 are in plain ASCII format (in paper source) and are also available at http://www-sdss.fnal.gov:8000/~dtucker/LCLG . Accepted for publication in the September 2000 issue of ApJ

    Supermarket top-up of Healthy Start vouchers increases fruit and vegetable purchases in low-income households

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    Stark, widening health and income inequalities in the United Kingdom underpin the need for increased support for low-income families to access affordable and nutritious foods. Using anonymised supermarket loyalty card transaction records, this study aimed to assess how an additional Healthy Start voucher (HSV) top-up of £2, redeemable only against fruit and vegetables (FVs), was associated with FV purchases among at-risk households. Transaction and redemption records from 150 loyalty card-holding households, living in northern England, who had engaged with the top-up scheme, were analysed to assess the potential overall population impact. Using a pre-post study design, 133 of these households' records from 2021 were compared with equivalent time periods in 2019 and 2020. Records were linked to product, customer and store data, permitting comparisons using Wilcoxon matched-pairs sign-ranked tests and relationships assessed with Spearman's Rho. These analyses demonstrated that 0.9 more portions of FV per day per household were purchased during the scheme compared to the 2019 baseline (p = 0.0017). The percentage of FV weight within total baskets also increased by 1.6 percentage points (p = 0.0242), although the proportional spend on FV did not change. During the scheme period, FV purchased was higher by 0.4 percentage points (p = 0.0012) and 1.6 percentage points (p = 0.0062) according to spend and weight, respectively, in top-up redeeming baskets compared to non-top-up redeeming baskets with at least one FV item and was associated with 5.5 more HSV ‘Suggested’ FV portions (p < 0.0001). The median weight of FV purchased increased from 41.83 kg in 2019 to 54.14 kg in 2021 (p = 0.0017). However, top-up vouchers were only redeemed on 9.1% of occasions where FV were purchased. In summary, this study provides novel data showing that safeguarding funds exclusively for FV can help to increase access to FV in low-income households. These results yield important insights to inform public policy aimed at levelling up health inequalities

    Fish in a barrel: police targeting of Brisbane’s ephemeral gay spaces in the pre-decriminalization era

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    Across history, and particularly in periods of criminalization, the gay community have often been forced to resort to public spaces—“beats”—to clandestinely seek out anonymized sex with partners who share their sexual preference. This article reframes the construction of gay beats as ephemeral spaces that prevails in existing sexuality literature. Instead, it shows that Brisbane’s beats were semi-permanent spaces with subcultural meaning to the local gay community—a fact that was used by police to target gay men during law enforcement’s attempts to reestablish a moral order in the postwar era. Using a combination of archival material, personal narratives and secondary sources, this article effectively reframes the concept of gay beats as transitory spaces, and instead argues that it was their permanence and resilience in Brisbane’s gay subculture that made them a perfect hunting ground for police looking to target a vulnerable homosexual community

    Appointing Women to Boards: Is There a Cultural Bias?

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    Companies that are serious about corporate governance and business ethics are turning their attention to gender diversity at the most senior levels of business (Institute of Business Ethics, Business Ethics Briefing 21:1, 2011). Board gender diversity has been the subject of several studies carried out by international organizations such as Catalyst (Increasing gender diversity on boards: Current index of formal approaches, 2012), the World Economic Forum (Hausmann et al., The global gender gap report, 2010), and the European Board Diversity Analysis (Is it getting easier to find women on European boards? 2010). They all lead to reports confirming the overall relatively low proportion of women on boards and the slow pace at which more women are being appointed. Furthermore, the proportion of women on corporate boards varies much across countries. Based on institutional theory, this study hypothesizes and tests whether this variation can be attributed to differences in cultural settings across countries. Our analysis of the representation of women on boards for 32 countries during 2010 reveals that two cultural characteristics are indeed associated with the observed differences. We use the cultural dimensions proposed by Hofstede (Culture’s consequences: International differences in work-related values, 1980) to measure this construct. Results show that countries which have the greatest tolerance for inequalities in the distribution of power and those that tend to value the role of men generally exhibit lower representations of women on boards

    Microstimulation of human somatosensory cortex evokes task-dependent, spatially patterned responses in motor cortex

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    The primary motor (M1) and somatosensory (S1) cortices play critical roles in motor control but the signaling between these structures is poorly understood. To fill this gap, we recorded – in three participants in an ongoing human clinical trial (NCT01894802) for people with paralyzed hands – the responses evoked in the hand and arm representations of M1 during intracortical microstimulation (ICMS) in the hand representation of S1. We found that ICMS of S1 activated some M1 neurons at short, fixed latencies consistent with monosynaptic activation. Additionally, most of the ICMS-evoked responses in M1 were more variable in time, suggesting indirect effects of stimulation. The spatial pattern of M1 activation varied systematically: S1 electrodes that elicited percepts in a finger preferentially activated M1 neurons excited during that finger’s movement. Moreover, the indirect effects of S1 ICMS on M1 were context dependent, such that the magnitude and even sign relative to baseline varied across tasks. We tested the implications of these effects for brain-control of a virtual hand, in which ICMS conveyed tactile feedback. While ICMS-evoked activation of M1 disrupted decoder performance, this disruption was minimized using biomimetic stimulation, which emphasizes contact transients at the onset and offset of grasp, and reduces sustained stimulation

    Evaluation Research and Institutional Pressures: Challenges in Public-Nonprofit Contracting

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    This article examines the connection between program evaluation research and decision-making by public managers. Drawing on neo-institutional theory, a framework is presented for diagnosing the pressures and conditions that lead alternatively toward or away the rational use of evaluation research. Three cases of public-nonprofit contracting for the delivery of major programs are presented to clarify the way coercive, mimetic, and normative pressures interfere with a sound connection being made between research and implementation. The article concludes by considering how public managers can respond to the isomorphic pressures in their environment that make it hard to act on data relating to program performance.This publication is Hauser Center Working Paper No. 23. The Hauser Center Working Paper Series was launched during the summer of 2000. The Series enables the Hauser Center to share with a broad audience important works-in-progress written by Hauser Center scholars and researchers

    The Noise Exposure Structured Interview (NESI): an instrument for the comprehensive estimation of lifetime noise exposure

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    Lifetime noise exposure is generally quantified by self report. The accuracy of retrospective self report is limited by respondent recall, but is also bound to be influenced by reporting procedures. Such procedures are of variable quality in current measures of lifetime noise exposure, and off-the-shelf instruments are not readily available. The Noise Exposure Structured Interview (NESI) represents an attempt to draw together some of the stronger elements of existing procedures and to provide solutions to their outstanding limitations. Reporting is not restricted to pre-specified exposure activities, and instead encompasses all activities that the respondent has experienced as noisy (defined based on sound level estimated from vocal effort). Changing exposure habits over time are reported by dividing the lifespan into discrete periods in which exposure habits were approximately stable, with life milestones used to aid recall. Exposure duration, sound level, and use of hearing protection are reported for each life period separately. Simple-to-follow methods are provided for the estimation of free-field sound level, the sound level emitted by personal listening devices, and the attenuation provided by hearing protective equipment. An energy-based means of combining the resulting data is supplied, along with a primarily energy-based method for incorporating firearm-noise exposure. Finally, the NESI acknowledges the need of some users to tailor the procedures; this flexibility is afforded and reasonable modifications are described. Competency needs of new users are addressed through detailed interview instructions (including troubleshooting tips) and a demonstration video. Limited evaluation data are available and future efforts at evaluation are proposed

    Clusters and Superclusters in the Sloan Digital Sky Survey

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    Two-dimensional high-resolution density field of galaxies of the Early Data Release of the Sloan Digital Sky Survey with a smoothing lengths 0.8 h^{-1} Mpc is applied to extract clusters of galaxies, and a low-resolution field with smoothing lengths 10^{-1} Mpc to extract superclusters of galaxies. We compare properties of density field clusters and superclusters with Abell clusters, and superclusters found on the basis of Abell clusters. We found that clusters in high-density environment have a luminosity a factor of about 5 higher than in low-density environment. There exists a large anisotropy between the SDSS Northern and Southern sample in the properties of clusters and superclusters: most luminous clusters and superclusters in the Northern sample are a factor of 2 more luminous than the respective systems in the Southern sample.Comment: 19 pages LaTeX text, 7 PostScript Figures, 7 jpg Figures (Figures 1, 2A,B,C,D, 3A,B,C,D, 4A,B, 5A,B, 12, 14), submitted to Astronomy and Astrophysic
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