2,696 research outputs found

    Sky maps without anisotropies in the cosmic microwave background are a better fit to WMAP's uncalibrated time ordered data than the official sky maps

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    The purpose of this reanalysis of the WMAP uncalibrated time ordered data (TOD) was two fold. The first was to reassess the reliability of the detection of the anisotropies in the official WMAP sky maps of the cosmic microwave background (CMB). The second was to assess the performance of a proposed criterion in avoiding systematic error in detecting a signal of interest. The criterion was implemented by testing the null hypothesis that the uncalibrated TOD was consistent with no anisotropies when WMAP's hourly calibration parameters were allowed to vary. It was shown independently for all 20 WMAP channels that sky maps with no anisotropies were a better fit to the TOD than those from the official analysis. The recently launched Planck satellite should help sort out this perplexing result.Comment: 11 pages with 1 figure and 2 tables. Extensively rewritten to explain the research bette

    Baltimore City Schools Need Many Things - A Personal Police Force is Not One of Them

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    Early Country Musician Doc Williams (1914-2011): Contributions to the Development of Country Music and Applications for a General Music Curriculum, Grades 3-5

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    The purpose of this study is to document early country musician Doc Williams’ musical career, to evaluate his specific contributions to early country music from 1932 to 1951, and to develop curriculum materials for grades 3-5 general music classes based on his music. I chose 1951 as the end point for this study because at that time Williams began frequent tours to the northeast and Canada. These later years, although worthy of attention, launched a new phase of his career, beyond the scope of this study. During the course of the study, I address the following questions: 1) What was the nature of Williams’ musical education and development as a musician? 2) What are his contributions to country music? 3) In what ways can Williams’ music be used in a general music curriculum for grades 3-5? Doc Williams was born Andrew Smik Jr. in Cleveland, Ohio, on June 26, 1914. He began his life-long musical career playing country music on radio in 1932. His success on WWVA’s “Wheeling Jamboree” contributed to his popularity in the Northeast and throughout Canada. Williams’ practices in country music are the reason many regard him as a pioneer of country music. Radio broadcasts, personal appearances, songwriting, song publishing, and recording were all important components of his life-long career. His music is exemplary of the early country music genre. Therefore, his contributions to early country music make his music worthy of study. Historically, country music has been marginalized in the music curriculum. This study demonstrates the relevance and value of early country music such as that of Williams in a general music curriculum.Master of ArtsMusic EducationUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/123006/1/Josephine_Cover-Masters_Thesis.pd

    Characterization of Collective Gaussian Attacks and Security of Coherent-State Quantum Cryptography

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    We provide a simple description of the most general collective Gaussian attack in continuous-variable quantum cryptography. In the scenario of such general attacks, we analyze the asymptotic secret-key rates which are achievable with coherent states, joint measurements of the quadratures and one-way classical communication.Comment: 4 pages, 1 figure + 1 Table, REVteX. More descriptive titl

    A variational principle for cyclic polygons with prescribed edge lengths

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    We provide a new proof of the elementary geometric theorem on the existence and uniqueness of cyclic polygons with prescribed side lengths. The proof is based on a variational principle involving the central angles of the polygon as variables. The uniqueness follows from the concavity of the target function. The existence proof relies on a fundamental inequality of information theory. We also provide proofs for the corresponding theorems of spherical and hyperbolic geometry (and, as a byproduct, in 1+11+1 spacetime). The spherical theorem is reduced to the euclidean one. The proof of the hyperbolic theorem treats three cases separately: Only the case of polygons inscribed in compact circles can be reduced to the euclidean theorem. For the other two cases, polygons inscribed in horocycles and hypercycles, we provide separate arguments. The hypercycle case also proves the theorem for "cyclic" polygons in 1+11+1 spacetime.Comment: 18 pages, 6 figures. v2: typos corrected, final versio

    Generalized relation between the relative entropy and dissipation for nonequilibrium systems

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    Recently, Kawai, Parrondo, and Van den Broeck have related dissipation to time-reversal asymmetry. We generalized the result by considering a protocol where the physical system is driven away from an initial thermal equilibrium state with temperature β0\beta_0 to a final thermal equilibrium state at a different temperature. We illustrate the result using a model with an exact solution, i.e., a particle in a moving one-dimensional harmonic well.Comment: 4 page

    Note on exponential families of distributions

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    We show that an arbitrary probability distribution can be represented in exponential form. In physical contexts, this implies that the equilibrium distribution of any classical or quantum dynamical system is expressible in grand canonical form.Comment: 5 page

    Parameter estimation in pair hidden Markov models

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    This paper deals with parameter estimation in pair hidden Markov models (pair-HMMs). We first provide a rigorous formalism for these models and discuss possible definitions of likelihoods. The model being biologically motivated, some restrictions with respect to the full parameter space naturally occur. Existence of two different Information divergence rates is established and divergence property (namely positivity at values different from the true one) is shown under additional assumptions. This yields consistency for the parameter in parametrization schemes for which the divergence property holds. Simulations illustrate different cases which are not covered by our results.Comment: corrected typo

    How much measurement independence is needed in order to demonstrate nonlocality?

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    If nonlocality is to be inferred from a violation of Bell's inequality, an important assumption is that the measurement settings are freely chosen by the observers, or alternatively, that they are random and uncorrelated with the hypothetical local variables. We study the case where this assumption is weakened, so that measurement settings and local variables are at least partially correlated. As we show, there is a connection between this type of model and models which reproduce nonlocal correlations by allowing classical communication between the distant parties, and a connection with models that exploit the detection loophole. We show that even if Bob's choices are completely independent, all correlations obtained from projective measurements on a singlet can be reproduced, with the correlation (measured by mutual information) between Alice's choice and local variables less than or equal to a single bit.Comment: 5 pages, 1 figure. v2 Various improvements in presentation. Results unchange

    Scanner Invariant Representations for Diffusion MRI Harmonization

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    Purpose: In the present work we describe the correction of diffusion-weighted MRI for site and scanner biases using a novel method based on invariant representation. Theory and Methods: Pooled imaging data from multiple sources are subject to variation between the sources. Correcting for these biases has become very important as imaging studies increase in size and multi-site cases become more common. We propose learning an intermediate representation invariant to site/protocol variables, a technique adapted from information theory-based algorithmic fairness; by leveraging the data processing inequality, such a representation can then be used to create an image reconstruction that is uninformative of its original source, yet still faithful to underlying structures. To implement this, we use a deep learning method based on variational auto-encoders (VAE) to construct scanner invariant encodings of the imaging data. Results: To evaluate our method, we use training data from the 2018 MICCAI Computational Diffusion MRI (CDMRI) Challenge Harmonization dataset. Our proposed method shows improvements on independent test data relative to a recently published baseline method on each subtask, mapping data from three different scanning contexts to and from one separate target scanning context. Conclusion: As imaging studies continue to grow, the use of pooled multi-site imaging will similarly increase. Invariant representation presents a strong candidate for the harmonization of these data
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