636 research outputs found

    Boards attributes that increase firm risk - evidence from the UK

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    Purpose – The aim of the paper is to identify the board attributes that significantly increase firm risk. The study aims to find if board size, percentage of non-executive directors, women on the board, a powerful CEO, equity ownership amongst executive board directors and institutional investor ownership, are associated with firm risk. This is the first study that examines which board attributes increase firm risk using a UK based sample. Design/methodology/approach – This empirical study collected secondary data from Bloomberg and Morningstar databases. The data sample is an unbalanced panel of 260 companies’ secondary data on FTSE 350 index in the UK, from 2005 to 2010. The data was statistically analysed using STATA. Findings – The study establishes the board attributes that were significantly related to firm risk. The results show that a board which can increase firm risk is one that is small in size,has high equity ownership amongst executive board directors and has high institutional investor ownership. Research limitations/implications – The governance culture and regulatory system in the UK is different from other countries. Since the data is a UK based sample, the results can lack generalisability. Practical implications – The results are useful for investors who invest in large firms, to have the knowledge about the board attributes that can increase firm risk. Regulators can also use the results to strengthen regulatory guidelines. Originality/value – This study fills the gap in knowledge in UK governance literature on the board attributes that can increase firm risk

    Coporate governance and firm risk

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    This study explores the relationship between the board governance structure and firm risk. Specifically, we develop a ‘Governance index’ based on four different aspects of the board: 1. Board composition, 2. Board leadership structure, 3. Board member characteristics and 4. Board processes and examine how the overall index relates to firm risk. The study is conducted using a sample of 268 UK firms from the FTSE 350 index, over the period 2005 to 2010. An index is constructed to capture the overall governance structure of the firm. Regressions of the index on three risk measures are examined. We find that the governance index that aggregates the four sets of board attributes is significantly negatively related to firm risk. Robustness tests confirm this result. A large number of studies have explored the relationship between the attributes of corporate boards and firm performance, with mixed results. A much smaller number of studies have looked at board attributes and firm risk, but these have either focused on financial sector firms alone, or have included only a single or a limited number of attributes. This study, utilizing a broad agency framework, seeks to extend the work on firm risk and board attributes, by both expanding industry sectors examined and employing a comprehensive set of board attributes. The findings have policy and practical implications for investors, regulators, and chairmen of boards of governors to the extent that they inform these constituencies about the set of board attributes that are associated with firm risk. This study is the first to utilize a comprehensive measure of governance and relate it to firm risk

    Techniques for measuring atmospheric aerosols at the High Resolution Fly's Eye experiment

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    We describe several techniques developed by the High Resolution Fly's Eye experiment for measuring aerosol vertical optical depth, aerosol horizontal attenuation length, and aerosol phase function. The techniques are based on measurements of side-scattered light generated by a steerable ultraviolet laser and collected by an optical detector designed to measure fluorescence light from cosmic-ray air showers. We also present a technique to cross-check the aerosol optical depth measurement using air showers observed in stereo. These methods can be used by future air fluorescence experiments.Comment: Accepted for publication in Astroparticle Physics Journal 16 pages, 9 figure

    Study of Small-Scale Anisotropy of Ultrahigh Energy Cosmic Rays Observed in Stereo by HiRes

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    The High Resolution Fly's Eye (HiRes) experiment is an air fluorescence detector which, operating in stereo mode, has a typical angular resolution of 0.6 degrees and is sensitive to cosmic rays with energies above 10^18 eV. HiRes is thus an excellent instrument for the study of the arrival directions of ultrahigh energy cosmic rays. We present the results of a search for anisotropies in the distribution of arrival directions on small scales (<5 degrees) and at the highest energies (>10^19 eV). The search is based on data recorded between 1999 December and 2004 January, with a total of 271 events above 10^19 eV. No small-scale anisotropy is found, and the strongest clustering found in the HiRes stereo data is consistent at the 52% level with the null hypothesis of isotropically distributed arrival directions.Comment: 4 pages, 3 figures. Matches accepted ApJL versio

    Does a 'direct' transfer protocol reduce time to coronary angiography for patients with non-ST-elevation acute coronary syndromes? A prospective observational study.

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    OBJECTIVE: National guidelines recommend 'early' coronary angiography within 96 h of presentation for patients with non-ST elevation acute coronary syndromes (NSTE-ACS). Most patients with NSTE-ACS present to their district general hospital (DGH), and await transfer to the regional cardiac centre for angiography. This care model has inherent time delays, and delivery of timely angiography is problematic. The objective of this study was to assess a novel clinical care pathway for the management of NSTE-ACS, known locally as the Heart Attack Centre-Extension or HAC-X, designed to rapidly identify patients with NSTE-ACS while in DGH emergency departments (ED) and facilitate transfer to the regional interventional centre for 'early' coronary angiography. METHODS: This was an observational study of 702 patients divided into two groups; 391 patients treated before the instigation of the HAC-X pathway (Pre-HAC-X), and 311 patients treated via the novel pathway (Post-HAC-X). Our primary study end point was time from ED admission to coronary angiography. We also assessed the length of hospital stay. RESULTS: Median time from ED admission to coronary angiography was 7.2 (IQR 5.1-10.2) days pre-HAC-X compared to 1.0 (IQR 0.7-2.0) day post-HAC-X (p<0.001). Median length of hospital stay was 3.0 (IQR 2.0-6.0) days post-HAC-X v 9.0 (IQR 6.0-14.0) days pre-HAC-X (p<0.0005). This equates to a reduction of six hospital bed days per NSTE-ACS admission. CONCLUSIONS: The introduction of this novel care pathway was associated with significant reductions in time to angiography and in total hospital bed occupancy for patients with NSTE-ACS

    A Measurement of Time-Averaged Aerosol Optical Depth using Air-Showers Observed in Stereo by HiRes

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    Air fluorescence measurements of cosmic ray energy must be corrected for attenuation of the atmosphere. In this paper we show that the air-showers themselves can yield a measurement of the aerosol attenuation in terms of optical depth, time-averaged over extended periods. Although the technique lacks statistical power to make the critical hourly measurements that only specialized active instruments can achieve, we note the technique does not depend on absolute calibration of the detector hardware, and requires no additional equipment beyond the fluorescence detectors that observe the air showers. This paper describes the technique, and presents results based on analysis of 1258 air-showers observed in stereo by the High Resolution Fly's Eye over a four year span.Comment: 7 pages, 3 figures, accepted for publication by Astroparticle Physics Journa

    On astrophysical solution to ultra high energy cosmic rays

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    We argue that an astrophysical solution to UHECR problem is viable. The pectral features of extragalactic protons interacting with CMB are calculated in model-independent way. Using the power-law generation spectrum Eγg\propto E^{-\gamma_g} as the only assumption, we analyze four features of the proton spectrum: the GZK cutoff, dip, bump and the second dip. We found the dip, induced by electron-positron production on CMB, as the most robust feature, existing in energy range 1×10184×10191\times 10^{18} - 4\times 10^{19} eV. Its shape is stable relative to various phenomena included in calculations. The dip is well confirmed by observations of AGASA, HiRes, Fly's Eye and Yakutsk detectors. The best fit is reached at γg=2.7\gamma_g =2.7, with the allowed range 2.55 - 2.75. The dip is used for energy calibration of the detectors. After the energy calibration the fluxes and spectra of all three detectors agree perfectly, with discrepancy between AGASA and HiRes at E>1×1020E> 1\times 10^{20} eV being not statistically significant. The agreement of the dip with observations should be considered as confirmation of UHE proton interaction with CMB. The dip has two flattenings. The high energy flattening at E1×1019E \approx 1\times 10^{19} eV automatically explains ankle. The low-energy flattening at E1×1018E \approx 1\times 10^{18} eV provides the transition to galactic cosmic rays. This transition is studied quantitatively. The UHECR sources, AGN and GRBs, are studied in a model-dependent way, and acceleration is discussed. Based on the agreement of the dip with existing data, we make the robust prediction for the spectrum at 1×10181×10201\times 10^{18} - 1\times 10^{20} eV to be measured in the nearest future by Auger detector.Comment: Revised version as published in Phys.Rev. D47 (2006) 043005 with a small additio

    Search for Point Sources of Ultra-High Energy Cosmic Rays Above 40 EeV Using a Maximum Likelihood Ratio Test

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    We present the results of a search for cosmic ray point sources at energies above 40 EeV in the combined data sets recorded by the AGASA and HiRes stereo experiments. The analysis is based on a maximum likelihood ratio test using the probability density function for each event rather than requiring an a priori choice of a fixed angular bin size. No statistically significant clustering of events consistent with a point source is found.Comment: 7 pages, 7 figures. Accepted for publication in The Astrophysical Journa

    An upper limit on the electron-neutrino flux from the HiRes detector

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    Air-fluorescence detectors such as the High Resolution Fly's Eye (HiRes) detector are very sensitive to upward-going, Earth-skimming ultrahigh energy electron-neutrino-induced showers. This is due to the relatively large interaction cross sections of these high-energy neutrinos and to the Landau-Pomeranchuk-Migdal (LPM) effect. The LPM effect causes a significant decrease in the cross sections for bremsstrahlung and pair production, allowing charged-current electron-neutrino-induced showers occurring deep in the Earth's crust to be detectable as they exit the Earth into the atmosphere. A search for upward-going neutrino-induced showers in the HiRes-II monocular dataset has yielded a null result. From an LPM calculation of the energy spectrum of charged particles as a function of primary energy and depth for electron-induced showers in rock, we calculate the shape of the resulting profile of these showers in air. We describe a full detector Monte Carlo simulation to determine the detector response to upward-going electron-neutrino-induced cascades and present an upper limit on the flux of electron-neutrinos.Comment: 13 pages, 3 figures. submitted to Astrophysical Journa
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