677 research outputs found

    Deterministic models of quantum fields

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    Deterministic dynamical models are discussed which can be described in quantum mechanical terms. -- In particular, a local quantum field theory is presented which is a supersymmetric classical model. The Hilbert space approach of Koopman and von Neumann is used to study the classical evolution of an ensemble of such systems. Its Liouville operator is decomposed into two contributions, with positive and negative spectrum, respectively. The unstable negative part is eliminated by a constraint on physical states, which is invariant under the Hamiltonian flow. Thus, choosing suitable variables, the classical Liouville equation becomes a functional Schroedinger equation of a genuine quantum field theory. -- We briefly mention an U(1) gauge theory with ``varying alpha'' or dilaton coupling where a corresponding quantized theory emerges in the phase space approach. It is energy-parity symmetric and, therefore, a prototype of a model in which the cosmological constant is protected by a symmetry.Comment: 6 pages; synopsis of hep-th/0510267, hep-th/0503069, hep-th/0411176 . Talk at Constrained Dynamics and Quantum Gravity - QG05, Cala Gonone (Sardinia, Italy), September 12-16, 2005. To appear in the proceeding

    Is there a relativistic nonlinear generalization of quantum mechanics?

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    Yes, there is. - A new kind of gauge theory is introduced, where the minimal coupling and corresponding covariant derivatives are defined in the space of functions pertaining to the functional Schroedinger picture of a given field theory. While, for simplicity, we study the example of an U(1) symmetry, this kind of gauge theory can accommodate other symmetries as well. We consider the resulting relativistic nonlinear extension of quantum mechanics and show that it incorporates gravity in the (0+1)-dimensional limit, where it leads to the Schroedinger-Newton equations. Gravity is encoded here into a universal nonlinear extension of quantum theory. The probabilistic interpretation, i.e. Born's rule, holds provided the underlying model has only dimensionless parameters.Comment: 10 pages; talk at DICE 2006 (Piombino, September 11-15, 2006); to appear in Journal of Physics: Conference Series (2007

    International Consensus on Differential Diagnosis and Management of Patients With Danon Disease: JACC State-of-the-Art Review

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    Danon disease is a rare X-linked autophagic vacuolar cardioskeletal myopathy associated with severe heart failure that can be accompanied with extracardiac neurologic, skeletal, and ophthalmologic manifestations. It is caused by loss of function variants in the LAMP2 gene and is among the most severe and penetrant of the genetic cardiomyopathies. Most patients with Danon disease will experience symptomatic heart failure. Male individuals generally present earlier than women and die of either heart failure or arrhythmia or receive a heart transplant by the third decade of life. Herein, the authors review the differential diagnosis of Danon disease, diagnostic criteria, natural history, management recommendations, and recent advances in treatment of this increasingly recognized and extremely morbid cardiomyopathy

    Quantum geometry and quantum algorithms

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    Motivated by algorithmic problems arising in quantum field theories whose dynamical variables are geometric in nature, we provide a quantum algorithm that efficiently approximates the colored Jones polynomial. The construction is based on the complete solution of Chern-Simons topological quantum field theory and its connection to Wess-Zumino-Witten conformal field theory. The colored Jones polynomial is expressed as the expectation value of the evolution of the q-deformed spin-network quantum automaton. A quantum circuit is constructed capable of simulating the automaton and hence of computing such expectation value. The latter is efficiently approximated using a standard sampling procedure in quantum computation.Comment: Submitted to J. Phys. A: Math-Gen, for the special issue ``The Quantum Universe'' in honor of G. C. Ghirard

    Emergence: Key physical issues for deeper philosophical inquiries

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    A sketch of three senses of emergence and a suggestive view on the emergence of time and the direction of time is presented. After trying to identify which issues philosophers interested in emergent phenomena in physics view as important I make several observations pertaining to the concepts, methodology and mechanisms required to understand emergence and describe a platform for its investigation. I then identify some key physical issues which I feel need be better appreciated by the philosophers in this pursuit. I end with some comments on one of these issues, that of coarse-graining and persistent structures.Comment: 16 pages. Invited Talk at the Heinz von Foerster Centenary International Conference on Self-Organization and Emergence: Emergent Quantum Mechanics (EmerQuM11). Nov. 10-13, 2011, Vienna, Austria. Proceedings to appear in J. Phys. (Conf. Series

    Emergence: Key physical issues for deeper philosophical inquiries

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    A sketch of three senses of emergence and a suggestive view on the emergence of time and the direction of time is presented. After trying to identify which issues philosophers interested in emergent phenomena in physics view as important I make several observations pertaining to the concepts, methodology and mechanisms required to understand emergence and describe a platform for its investigation. I then identify some key physical issues which I feel need be better appreciated by the philosophers in this pursuit. I end with some comments on one of these issues, that of coarse-graining and persistent structures.Comment: 16 pages. Invited Talk at the Heinz von Foerster Centenary International Conference on Self-Organization and Emergence: Emergent Quantum Mechanics (EmerQuM11). Nov. 10-13, 2011, Vienna, Austria. Proceedings to appear in J. Phys. (Conf. Series

    The Cost-Effectiveness of Early Access to HIV Services and Starting cART in the UK 1996–2008

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    To calculate use, cost and cost-effectiveness of people living with HIV (PLHIV) starting routine treatment and care before starting combination antiretroviral therapy (cART) and PLHIV starting first-line 2NRTIs+NNRTI or 2NRTIs+PI(boosted), comparing PLHIV with CD4≤200 cells/mm3 and CD4>200 cells/mm3. Few studies have calculated the use, cost and cost-effectiveness of routine treatment and care before starting cART and starting cART above and below CD4 200 cells/mm3.Use, costs and cost-effectiveness were calculated for PLHIV in routine pre-cART and starting first-line cART, comparing CD4≤200 cells/mm3 with CD4>200 cells/mm3 (2008 UK prices).cART naïve patients CD4≤200 cells/mm3 had an annual cost of £6,407 (95%CI £6,382 to £6,425) PPY compared with £2,758 (95%CI £2,752 to £2,761) PPY for those with CD4>200 cells/mm3; cost per life year gained of pre-cART treatment and care for those with CD4>200 cells/mm3 was £1,776 (cost-saving to £2,752). Annual cost for starting 2NRTIs+NNRTI or 2NRTIs+PI(boosted) with CD4≤200 cells/mm3 was £12,812 (95%CI £12,685-£12,937) compared with £10,478 (95%CI £10,376-£10,581) for PLHIV with CD4>200 cells/mm3. Cost per additional life-year gained on first-line therapy for those with CD4>200 cells/mm3 was £4639 (£3,967 to £2,960).PLHIV starting to use HIV services before CD4≤200 cells/mm3 is cost-effective and enables them to be monitored so they start cART with a CD4>200 cells/mm3, which results in better outcomes and is cost-effective. However, 25% of PLHIV accessing services continue to present with CD4≤200 cells/mm3. This highlights the need to investigate the cost-effectiveness of testing and early treatment programs for key populations in the UK

    The state of the Martian climate

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    60°N was +2.0°C, relative to the 1981–2010 average value (Fig. 5.1). This marks a new high for the record. The average annual surface air temperature (SAT) anomaly for 2016 for land stations north of starting in 1900, and is a significant increase over the previous highest value of +1.2°C, which was observed in 2007, 2011, and 2015. Average global annual temperatures also showed record values in 2015 and 2016. Currently, the Arctic is warming at more than twice the rate of lower latitudes

    Intravascular Ultrasound (IVUS): A Potential Arthroscopic Tool for Quantitative Assessment of Articular Cartilage

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    Conventional ultrasound examination of the articular cartilage performed externally on the body surface around the joint has limited accuracy due to the inadequacy in frequency used. In contrast to this, minimally invasive arthroscopy-based ultrasound with adequately high frequency may be a better alternative to assess the cartilage. Up to date, no special ultrasound transducer for imaging the cartilage in arthroscopic use has been designed. In this study, we introduced the intravascular ultrasound (IVUS) for this purpose. An IVUS system with a catheter-based probe (Ø ≈ 1mm) was used to measure the thickness and surface acoustical reflection of the bovine patellar articular cartilage in vitro before and after degeneration induced by enzyme treatments. Similar measurement was performed using another high frequency ultrasound system (Vevo) with a probe of much larger size and the results were compared between the two systems. The thickness measured using IVUS was highly correlated (r = 0.985, p < 0.001) with that obtained by Vevo. Thickness and surface reflection amplitude measured using IVUS on the enzymatically digested articular cartilage showed changes similar to those obtained by Vevo, which were expectedly consistent with previous investigations. IVUS can be potentially used for the quantitative assessment of articular cartilage, with its ready-to-use arthroscopic feature

    Women convicted for violent offenses: Adverse childhood experiences, low level of education and poor mental health

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    <p>Abstract</p> <p>Background</p> <p>In past years, the female offender population has grown, leading to an increased interest in the characteristics of female offenders. The aim of this study was to assess the prevalence of female violent offending in a Swiss offender population and to compare possible socio-demographic and offense-related gender differences.</p> <p>Methods</p> <p>Descriptive and bivariate logistic regression analyses were performed for a representative sample of N = 203 violent offenders convicted in Zurich, Switzerland.</p> <p>Results</p> <p>7.9% (N = 16) of the sample were female. Significant gender differences were found: Female offenders were more likely to be married, less educated, to have suffered from adverse childhood experiences and to be in poor mental health. Female violent offending was less heterogeneous than male violent offending, in fact there were only three types of violent offenses females were convicted for in our sample: One third were convicted of murder, one third for arson and only one woman was convicted of a sex offense.</p> <p>Conclusions</p> <p>The results of our study point toward a gender-specific theory of female offending, as well as toward the importance of developing models for explaining female criminal behavior, which need to be implemented in treatment plans and intervention strategies regarding female offenders.</p
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