1,538 research outputs found

    TACMB-1: The Theory of Anisotropies in the Cosmic Microwave Background (Bibliographic Resource Letter)

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    This Resource Letter provides a guide to the literature on the theory of anisotropies in the cosmic microwave background. Journal articles, web pages, and books are cited for the following topics: discovery, cosmological origin, early work, recombination, general CMB anisotropy references, primary CMB anisotropies (numerical, analytical work), secondary effects, Sunyaev-Zel'dovich effect(s), lensing, reionization, polarization, gravity waves, defects, topology, origin of fluctuations, development of fluctuations, inflation and other ties to particle physics, parameter estimation, recent constraints, web resources, foregrounds, observations and observational issues, and gaussianity.Comment: AJP/AAPT Bibliographic Resource letter published Feb. 2002, 24 pages (9 of text), 1 figur

    Combining galaxy and 21cm surveys

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    Acoustic waves traveling through the early Universe imprint a characteristic scale in the clustering of galaxies, QSOs and inter-galactic gas. This scale can be used as a standard ruler to map the expansion history of the Universe, a technique known as Baryon Acoustic Oscillations (BAO). BAO offer a high-precision, low-systematics means of constraining our cosmological model. The statistical power of BAO measurements can be improved if the `smearing' of the acoustic feature by non-linear structure formation is undone in a process known as reconstruction. In this paper we use low-order Lagrangian perturbation theory to study the ability of 21 21\,cm experiments to perform reconstruction and how augmenting these surveys with galaxy redshift surveys at relatively low number densities can improve performance. We find that the critical number density which must be achieved in order to benefit 21 21\,cm surveys is set by the linear theory power spectrum near its peak, and corresponds to densities achievable by upcoming surveys of emission line galaxies such as eBOSS and DESI. As part of this work we analyze reconstruction within the framework of Lagrangian perturbation theory with local Lagrangian bias, redshift-space distortions, k{\bf k}-dependent noise and anisotropic filtering schemes.Comment: 10 pages, final version to appear in MNRAS, helpful suggestions from referee and others include

    A Comparison of Simulated and Analytic Major Merger Counts

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    We use large volume, high resolution, N-body simulations of 3 different Λ\LambdaCDM models, with different clustering strengths, to generate dark matter halo merging histories. Over the reliable range of halo masses, roughly galaxy groups to rich clusters of galaxies, we quantify the number density of major mergers for two different time intervals and compare with analytic predictions based on the extended Press-Schechter (1974) theory.Comment: 24 pages, 18 figures. Comments welcome. Final version to appear MNRAS, helpful suggestions from referee and others incorporate

    Constraints on the correlation between QSO luminosity and host halo mass from high-redshift quasar clustering

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    Recent measurements of high-redshift QSO clustering from the Sloan Digital Sky Survey indicate that QSOs at z~4 have a bias b~14. We find that this extremely high clustering amplitude, combined with the corresponding space density, constrains the dispersion in the L-Mhalo relation to be less than 50% at 99% confidence for the most conservative case of a 100% duty cycle. This upper limit to the intrinsic dispersion provides as strong a constraint as current upper limits to the intrinsic dispersion in the local M_BH-sigma relation and the ratio of bolometric to Eddington luminosity of luminous QSOs.Comment: 6 pages, 4 figures. Minor revisions to address questions from referee. References update

    Algebras in Higher Dimensional Statistical Mechanics - the Exceptional Partition (MEAN Field) Algebras

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    We determine the structure of the partition algebra Pn(Q)P_n(Q) (a generalized Temperley-Lieb algebra) for specific values of Q \in \C, focusing on the quotient which gives rise to the partition function of nn site QQ-state Potts models (in the continuous QQ formulation) in arbitrarily high lattice dimensions (the mean field case). The algebra is non-semi-simple iff QQ is a non-negative integer less than nn. We determine the dimension of the key irreducible representation in every specialization.Comment: 4 page

    Heat Conduction and Magnetic Phase Behavior in Electron-Doped Ca_{1-x} La_x MnO_3(0 <= x <= 0.2)

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    Measurements of thermal conductivity (kappa) vs temperature are reported for a series of Ca_{1-x} La_x MnO_3(0 <= x <= 0.2) specimens. For the undoped (x=0), G-type antiferromagnetic compound a large enhancement of kappa below the Neel temperature (T_N ~ 125 K) indicates a strong coupling of heat-carrying phonons to the spin system. This enhancement exhibits a nonmonotonic behavior with increasing x and correlates remarkably well with the small ferromagnetic component of the magnetization reported previously [Neumeier and Cohn, Phys. Rev. B 61 14319 (2000).] Magnetoelastic polaron formation appears to underly the behavior of kappa and the magnetization at x <= 0.02.Comment: submitted to PRB; 4 pp., 4 Fig.'s, RevTex

    Multidisciplinary team meetings in palliative care: an ethnographic study

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    OBJECTIVES: Multidisciplinary team meetings are a regular feature in the provision of palliative care, involving a range of professionals. Yet, their purpose and best format are not necessarily well understood or documented. This article describes how hospital and community-based palliative care multidisciplinary team meetings operate to elucidate some of their main values and offer an opportunity to share examples of good practice. METHODS: Ethnographic observations of over 70 multidisciplinary team meetings between May 2018 and January 2020 in hospital and community palliative care settings in intercity London. These observations were part of a larger study examining palliative care processes. Fieldnotes were thematically analysed. RESULTS: This article analyses how the meetings operated in terms of their setup, participants and general order of business. Meetings provided a space where patients, families and professionals could be cared for through regular discussions of service provision. CONCLUSIONS: Meetings served a variety of functions. Alongside discussing the more technical, clinical and practical aspects that are formally recognised aspects of the meetings, an additional core value was enabling affectual aspects of dealing with people who are dying to be acknowledged and processed collectively. Insight into how the meetings are structured and operate offer input for future practice

    The Blob Algebra and the Periodic Temperley-Lieb Algebra

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    We determine the structure of two variations on the Temperley-Lieb algebra, both used for dealing with special kinds of boundary conditions in statistical mechanics models. The first is a new algebra, the `blob' algebra (the reason for the name will become obvious shortly!). We determine both the generic and all the exceptional structures for this two parameter algebra. The second is the periodic Temperley-Lieb algebra. The generic structure and part of the exceptional structure of this algebra have already been studied. Here we complete the analysis, using results from the study of the blob algebra.Comment: 12 page
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