1,387 research outputs found

    Centrality dependence of two-particle number and transverse momentum correlations in 200 gev au+au collisions at rhic

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    We present plots of the pattern of particle formation in sqrtsNN=200sqrt{s_{NN}}=200 GeV Au+Au heavy ion collisions at the Relativistic Heavy Ion Collider (RHIC) using three different two-particle correlation measurements of number and transverse momentum as a function of relative azimuth, pseudorapidity and centrality. All three observables show the onset of a ``ridge feature of enhanced correlations in pseudorapidity with increasing centrality. The plots of real data are compared to plots of simulations using RQMD data and data from a simple ``cluster\u27\u27 model. The intent of the analysis is to analyze the role of radial flow in the onset of the ridge, and to offer canonical representations of the observables

    HARMONI: advancing science with the next-generation integral field spectrograph

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    We start by investigating the noise behaviour of Teledyne HxRG infrared detectors. We look at data from KMOS H2RG darks, along with data from a MOONS engineering grade H4RG detector. From these we determine read noise distributions for the HxRG detectors, and identify a number of other non-uniform noise contributions. We then incorporate this information, along with a pre-existing HxRG noise generation tool, into HSIM. We then use this new advanced detector systematics (ADS) mode to produce simulations investigating the point source sensitivities, spatial variation of noise, reproducibility of recovered point source flux, and signal-to-noise ratio (SNR) for a number of different noise components. We determine from this that these additional detector noise effects provide non-trivial contributions to the noise profile of the detectors. In particular we find pink noise to be problematic, as it is a spatially-varying noise component that has a large impact on the overall SNR. We recommend careful use of the detector reference pixels to correct this, accounting for the potential for bad pixels within these. We also look at the impact of an under-illuminated spectrograph entrance slit on telluric correction. We model the SINFONI 250x125 mas H-band line spread function (LSF) and vary the level of the input illumination. From this we determine an expected reduction in LSF width of 14%. We then use observations of CD-23 13701 and Callisto taken with SINFONI with adaptive optics (AO) correction to confirm a result of 14.0+/-2.1% when fitted using molecfit. We attempt four methods of telluric correction; directly using CD-23 13701 as a telluric standard star, a synthetic spectrum created from molecfit run on CD-23 13701, this synthetic spectrum convolved with the appropriate LSF, and a synthetic spectrum created from molecfit run on the Callisto data. We perform this analysis on multiple spaxels within the Callisto data, and determine average residual sum of squares of 0.43, 0.34, 0.30, and 0.29 for the four methods. We determine from this that inadequate knowledge of the LSF leads to systematically worse telluric correction. Provided the LSF is known, the level of correction is similar between using a telluric standard star or the science target itself, with the remaining differences partly explained by variations in the atmospheric profile between the observations. We end with testing a science case of HARMONI; recovering spatially resolved kinematics from high redshift galaxies. We use the NUTFB simulation to create a galaxy at an effective redshift of 1.44. We then produce a number of simulations using HSIM to determine how well we can recover the rotation curve and star formation rate (SFR), varying the simulated observation time and spectral resolution. We determine that 1 hour of HARMONI observation is sufficient to recover the kinematics to the point at which we become limited by effects within the galaxy. We also investigate the impact of the AO point spread function (PSF), particularly showing the effects of the PSF wings smearing out the rotation curve, as well as differences in the kinematics as a result of PSF elongation

    Where is Public Sector Auditing: A Comparative Analysis

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    This chapter summarises the analysis of the preceding chapters. Whilst different countries use different models for their audit, some continuities do emerge. The audit explosion has led to the advance of both financial and performance audit. Inspection however remains an infrequent feature of the audit landscape. Many countries have a localised system of local audit in which the role and influence of audit is variable. Furthermore, the audit of local government lacks a clear democratic role at the moment

    Holding the Government to Account for its Finances: The ‘Unsung’ Heroes of the UK Parliament Scrutiny Unit

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    Purpose This paper describes the role and remit of the Scrutiny Unit, which assists Members of Parliament (MPs) with the analysis of accounting data. Design/Methodology/Approach The analysis is developed through an understanding of the secondary literature and practical experience of the work of the Unit. Findings The Scrutiny Unit is an unappreciated and yet vital part of the way in which financial scrutiny operates within the UK Parliament. It translates to MPs key financial and economic documents including the budget and accounts. It is a unique institution, covering the entire financial cycle of approval and accountability within Parliament. Originality This is the first descriptive piece on the Unit in an accounting journal and contributes to our understanding of how financial accountability works within the UK Parliament
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