990 research outputs found

    The Impact of Wrong Assumptions in BAO Reconstruction

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    The process of density field reconstruction enhances the statistical power of distance scale measurements using baryon acoustic oscillations (BAO). During this process a fiducial cosmology is assumed in order to convert sky coordinates and redshifts into distances; fiducial bias and redshift-space-distortion parameters are also assumed in this procedure. We analytically assess the impact of incorrect cosmology and bias assumptions on the post-reconstruction power spectra using low-order Lagrangian perturbation theory, deriving general expressions for the incorrectly reconstructed spectra. We find that the BAO peak location appears to shift only by a negligible amount due to wrong assumptions made during reconstruction. However, the shape of the BAO peak and the quadrupole amplitude can be affected by such errors (at the percent- and five-percent-level respectively), which potentially could cause small biases in parameter inference for future surveys; we outline solutions to such complications.Comment: 18 pages, 3 figures; comments welcome. v2 matches JCAP accepted versio

    The detection of the imprint of filaments on cosmic microwave background lensing

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    Galaxy redshift surveys, such as 2dF, SDSS, 6df, GAMA and VIPERS, have shown that the spatial distribution of matter forms a rich web, known as the cosmic web. The majority of galaxy survey analyses measure the amplitude of galaxy clustering as a function of scale, ignoring information beyond a small number of summary statistics. Since the matter density field becomes highly non-Gaussian as structure evolves under gravity, we expect other statistical descriptions of the field to provide us with additional information. One way to study the non-Gaussianity is to study filaments, which evolve non-linearly from the initial density fluctuations produced in the primordial Universe. In our study, we report the first detection of CMB (Cosmic Microwave Background) lensing by filaments and we apply a null test to confirm our detection. Furthermore, we propose a phenomenological model to interpret the detected signal and we measure how filaments trace the matter distribution on large scales through filament bias, which we measure to be around 1.5. Our study provides a new scope to understand the environmental dependence of galaxy formation. In the future, the joint analysis of lensing and Sunyaev-Zel'dovich observations might reveal the properties of `missing baryons', the vast majority of the gas which resides in the intergalactic medium and has so far evaded most observations

    Cyclic AMP metabolism and adenylate cyclase concentration in patients with advanced hepatic cirrhosis

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    Glucagon was tested for its effect on plasma adenosine 3′,5′-cyclic monophosphate (cyclic AMP), insulin, and glucose in healthy subjects and in patients with advanced cirrhosis of the liver. In the normal subjects, intravenous infusion of glucagon caused a significant increase in plasma cyclic AMP, glucose, and insulin. In advanced cirrhotics, plasma cyclic AMP, glucose, and insulin did not increase. Adenylate cyclase concentration was measured in liver tissue from end stage cirrhotic patients and from brain-dead organ donors whose cardiovascular function was maintained in a stable state. Basal and total adenylate cyclase concentration were not different in the two groups. Adenylate cyclase from the livers of advanced cirrhotics was, however, significantly less responsive to glucagon stimulation than was that from donor livers. Hepatocytes in advanced cirrhosis have abnormal metabolic behavior characterized by abnormal adenylate cyclase-cyclic AMP response to hormonal stimulation. © 1978

    The Atacama Cosmology Telescope: A Measurement of the Cosmic Microwave Background Power Spectrum at 148 and 218 GHz from the 2008 Southern Survey

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    We present measurements of the cosmic microwave background (CMB) power spectrum made by the Atacama Cosmology Telescope at 148 GHz and 218 GHz, as well as the cross-frequency spectrum between the two channels. Our results clearly show the second through the seventh acoustic peaks in the CMB power spectrum. The measurements of these higher-order peaks provide an additional test of the {\Lambda}CDM cosmological model. At l > 3000, we detect power in excess of the primary anisotropy spectrum of the CMB. At lower multipoles 500 < l < 3000, we find evidence for gravitational lensing of the CMB in the power spectrum at the 2.8{\sigma} level. We also detect a low level of Galactic dust in our maps, which demonstrates that we can recover known faint, diffuse signals.Comment: 19 pages, 13 figures. Submitted to ApJ. This paper is a companion to Hajian et al. (2010) and Dunkley et al. (2010

    Navigating the Looking Glass:Severing the Lawyer's Head in <i>Arkham Asylum</i>

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    Reading Arkham Asylum jurisprudentially, we encounter a story of the meeting of reason and unreason in the context of justice – of conscious law and its unconscious threat. Batman’s exploration of the Asylum is symbolic of the legal unconscious, and reflects the processes of repression that can be seen in dominant legal knowledge. A threat to this dominant knowledge can be seen in Two-Face’s reliance on his coin to ‘judge’ his victims. Moreover, Arkham Asylum configures the threat of law’s unconscious as the lawyer’s severed head inside the house of law. Ultimately, Batman’s journey through Arkham Asylum reminds law of the aesthetic and irrational contexts that it strives to deny and from which it seeks to defend itself – and that cultural legal studies explores. It recalls the unreason outside law’s logic, the chaos outside its order, the madness outside its sanity. The lesson of Batman’s encounters in the Asylum is that we should remember the ‘madness’ outside the legal order, and thus recognise that law is always already more than its conscious ‘sanity’ can contain

    The angular clustering of infrared-selected obscured and unobscured quasars

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    This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. ©: 2014 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.Recent studies of luminous infrared-selected active galactic nuclei (AGN) suggest that the reddest, most obscured objects display a higher angular clustering amplitude, and thus reside in higher mass darkmatter haloes. This is a direct contradiction to the prediction of the simplest unification-by-orientation models of AGN and quasars. However, clustering measurements depend strongly on the 'mask' that removes low-quality data and describes the sky and selection function.We find that applying a robust, conservative mask to WISE-selected quasars yields a weaker but still significant difference in the bias between obscured and unobscured quasars. These findings are consistent with results from previous Spitzer surveys, and removes any scale dependence of the bias. For obscured quasars with =0.99, we measure a bias of bq = 2.67 ± 0.16, corresponding to a halo mass of log(Mh/M⊙h-1) = 13.3 ± 0.1, while for unobscured sources with = 1.04 we find bq = 2.04 ± 0.17 with a halo mass log(Mh/M⊙h-1) = 12.8 ± 0.1. This improved measurement indicates that WISE-selected obscured quasars reside in haloes only a few times more massive than the haloes of their unobscured counterparts, a reduction in the factor of ∼10 larger halo mass as has been previously reported using WISE-selected samples. Additionally, an abundance matching analysis yields lifetimes for both obscured and unobscured quasar phases on the order of a few 100 Myr (∼1 per cent of the Hubble time) - however, the obscured phase lasts roughly twice as long, in tension with many model predictions.Peer reviewe

    The incidence of unpleasant dreams after sub-anaesthetic ketamine

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    Ketamine is an N-methyl-D-aspartate (NMDA)receptor antagonist with psychotogenic effects and for whichthere are diverse reports of whether pleasant or unpleasantdreams result during anaesthesia, post-operatively or aftersub-anaesthetic use. The aim was to assess in healthy volunteers the incidence ofunpleasant dreams over the three nights after receiving asub-anaesthetic dose of ketamine, in comparison to placebo,and with retrospective home nightmare frequency as acovariate.Thirty healthy volunteers completed questionnairesabout retrospective home dream recall and were then giveneither ketamine or placebo. Ketamine resulted in significantly more meandream unpleasantness relative to placebo and caused athreefold increase in the odds ratio for the incidence of anunpleasant dream. The number of dreams reported over thethree nights did not differ between the groups. Theincidence of unpleasant dreams after ketamine use waspredicted by retrospectively assessed nightmare frequencyat home.Ketamine causes unpleasant dreams over thethree post-administration nights. This may be evidence of aresidual psychotogenic effect that is not found on standardself-report symptomatology measures or a result of disturbedsleep electrophysiology. The results have theoretical implications for the relationship between nightmares and schizotypy
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