315 research outputs found

    A General Rate Duality of the MIMO Multiple Access Channel and the MIMO Broadcast Channel

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    We present a general rate duality between the multiple access channel (MAC) and the broadcast channel (BC) which is applicable to systems with and without nonlinear interference cancellation. Different to the state-of-the-art rate duality with interference subtraction from Vishwanath et al., the proposed duality is filter-based instead of covariance-based and exploits the arising unitary degree of freedom to decorrelate every point-to-point link. Therefore, it allows for noncooperative stream-wise decoding which reduces complexity and latency. Moreover, the conversion from one domain to the other does not exhibit any dependencies during its computation making it accessible to a parallel implementation instead of a serial one. We additionally derive a rate duality for systems with multi-antenna terminals when linear filtering without interference (pre-)subtraction is applied and the different streams of a single user are not treated as self-interference. Both dualities are based on a framework already applied to a mean-square-error duality between the MAC and the BC. Thanks to this novel rate duality, any rate-based optimization with linear filtering in the BC can now be handled in the dual MAC where the arising expressions lead to more efficient algorithmic solutions than in the BC due to the alignment of the channel and precoder indices.Comment: Submitted to IEEE Globecom 2008; Fixed dimensions of channel matrix H_k and covariance matrix Z_k, slightly modified conclusio

    Perceived weight status and risk of weight gain across life in US and UK adults

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    Background: Correctly identifying oneself as being overweight is presumed to be a prerequisite to successful weight management. The present research examined the effect that perceiving oneself as being ‘overweight’ has on risk of future weight gain in US and UK adults. Methods: Data from three longitudinal studies; US National Longitudinal Study of Adolescent Health (Add Health) 2001/2002–2008/2009, UK National Child Development Study (NCDS) 1981–2002/2004, and Midlife in the United States (MIDUS) 1995/1996–2004/2005, were used to examine the impact of perceiving oneself as being overweight on weight gain across adulthood in over 14 000 US and UK adults. Results: Participants who perceived their weight status as being overweight were at an increased risk of subsequent weight gain. This effect was observed irrespective of weight status at baseline and whether weight status perceptions were accurate or inaccurate. In the MIDUS sample, perceiving oneself as being overweight was associated with overeating in response to stress and this mediated the relationship between perceived overweight and weight gain. Conclusions: Perceiving oneself as being ‘overweight’ is counter-intuitively associated with an increased risk of future weight gain among US and UK adults

    Concert recording 2015-03-05

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    [Track 01]. Three contrapuncti from The art of fugue BWV 1080. Contrapunctus I ; [Track 02]. Contrapunctus IV ; [Track 03]. Contrapunctus IX / Johann Sebastian Bach -- [Track 04]. Premier quatuor op. 53. Adagio-allegro ; [Track 05]. Adagio sostenuto ; [Track 06]. Allegro vivace ; [Track 07]. Allegretto / Jean Baptiste Singelee -- [Track 08]. Saxophone quartet. Molto moderato ; [Track 09]. Andantio giovale ; [Track 10]. Adagio-allegro molto ; [Track 11]. Recitatives ; Presto meccanico / Stephen Dankner

    Momentum distribution function and short-range correlations of the warm dense electron gas -- ab initio quantum Monte Carlo results

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    In a classical plasma the momentum distribution, n(k)n(k), decays exponentially, for large kk, and the same is observed for an ideal Fermi gas. However, when quantum and correlation effects are relevant simultaneously, an algebraic decay, n∞(k)∼k−8n_\infty(k)\sim k^{-8} has been predicted. This is of relevance for cross sections and threshold processes in dense plasmas that depend on the number of energetic particles. Here we present extensive \textit{ab initio} results for the momentum distribution of the nonideal uniform electron gas at warm dense matter conditions. Our results are based on first principle fermionic path integral Monte Carlo (CPIMC) simulations and clearly confirm the k−8k^{-8} asymptotic. This asymptotic behavior is directly linked to short-range correlations which are analyzed via the on-top pair distribution function (on-top PDF), i.e. the PDF of electrons with opposite spin. We present extensive results for the density and temperature dependence of the on-top PDF and for the momentum distribution in the entire momentum range

    On designing safe and flexible embedded DSLs with Java 5

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    AbstractAlthough embedded DSLs are widely used in both functional and dynamic languages they are yet to be widely accepted in the Java community. The best available examples are projects like jMock and Hibernate Criteria Query. In this paper we introduce the design of three novel practical embedded DSLs that we designed to showcase the power of Java language and specifically the changes introduced in Java 5. One of those DSLs is fully implemented as an open source project and is gathering momentum in the community. We proceed to discuss the approaches that allow designing safe and flexible DSLs by extracting generic patterns where possible and describing more specific idioms where necessary. It is our goal that this paper would serve as a starting point for someone designing an embedded DSL that takes full advantage of the Java 5 features

    Fabrication and Characterization of Single-Crystal Diamond Membranes for Quantum Photonics with Tunable Microcavities

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    The development of quantum technologies is one of the big challenges in modern research. Acrucial component for many applications is an efficient, coherent spin–photon interface, and coupling single-color centers in thin diamond membranes to a microcavity is a promising approach. To structure such micrometer thin single-crystal diamond (SCD) membranes with a good quality, it is important to minimize defects originating from polishing or etching procedures. Here, we report on the fabrication of SCD membranes, with various diameters, exhibiting a low surface roughness down to 0.4 nm on a small area scale, by etching through a diamond bulk mask with angled holes. A significant reduction in pits induced by micromasking and polishing damages was accomplished by the application of alternating Ar/Cl2 + O2 dry etching steps. By a variation of etching parameters regarding the Ar/Cl2 step, an enhanced planarization of the surface was obtained, in particular, for surfaces with a higher initial surface roughness of several nanometers. Furthermore, we present the successful bonding of an SCD membrane via van der Waals forces on a cavity mirror and perform finesse measurements which yielded values between 500 and 5000, depending on the position and hence on the membranethickness. Our results are promising for, e.g., an efficient spin–photon interface

    Biomechanical testing of zirconium dioxide osteosynthesis system for Le Fort I advancement osteotomy fixation

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    The following work is the first evaluating the applicability of 3D printed zirconium dioxide ceramic miniplates and screws to stabilize maxillary segments following a Le-Fort I advancement surgery. Conventionally used titanium and individual fabricated zirconium dioxide miniplates were biomechanically tested and compared under an occlusal load of 120N and 500N using 3D finite element analysis. The overall model consisted of 295,477 elements. Under an occlusal load of 500N a safety factor before plastic deformation respectively crack of 2.13 for zirconium dioxide and 4.51 for titanium miniplates has been calculated. From a biomechanical point of view 3D printed ZrO2 mini-plates and screws are suggested to constitute an appropriate patient specific and metal-free solution for maxillary stabilization after Le Fort I osteotomy
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