3,942 research outputs found

    Flavor and chiral oscillations with Dirac wave packets

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    We report about recent results on Dirac wave packets in the treatment of neutrino flavor oscillation where the initial localization of a spinor state implies an interference between positive and negative energy components of mass-eigenstate wave packets. A satisfactory description of fermionic particles requires the use of the Dirac equation as evolution equation for the mass-eigenstates. In this context, a new flavor conversion formula can be obtained when the effects of chiral oscillation are taken into account. Our study leads to the conclusion that the fermionic nature of the particles, where chiral oscillations and the interference between positive and negative frequency components of mass-eigenstate wave packets are implicitly assumed, modifies the standard oscillation probability. Nevertheless, for ultra-relativistic particles and sharply peaked momentum distributions, we can analytically demonstrate that these modifications introduce correction factors proportional to (m12/p0) square which are practically un-detectable by any experimental analysisComment: 16 pages, 2 figure

    A tool for model-checking Markov chains

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    Markov chains are widely used in the context of the performance and reliability modeling of various systems. Model checking of such chains with respect to a given (branching) temporal logic formula has been proposed for both discrete [34, 10] and continuous time settings [7, 12]. In this paper, we describe a prototype model checker for discrete and continuous-time Markov chains, the Erlangen-Twente Markov Chain Checker EÎMC2, where properties are expressed in appropriate extensions of CTL. We illustrate the general benefits of this approach and discuss the structure of the tool. Furthermore, we report on successful applications of the tool to some examples, highlighting lessons learned during the development and application of EÎMC2

    CP violation in the lepton sector with Majorana neutrinos

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    We study CP violation in the lepton sector in extended models with right-handed neutrinos, without and with left-right symmetry, and with arbitrary mass terms. We find the conditions which must be satisfied by the neutrino and charged lepton mass matrices for CP conservation. These constraints, which are independent of the choice of weak basis, are proven to be also sufficient in simple cases. This invariant formulation makes apparent the necessary requirements for CP violation, as well as the size of CP violating effects. As an example, we show that CP violation can be much larger in left-right symmetric models than in models with only additional right-handed neutrinos, {\it i.e.}, without right-handed currents.Comment: 19 page

    A Markov Chain Model Checker

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    Markov chains are widely used in the context of performance and reliability evaluation of systems of various nature. Model checking of such chains with respect to a given (branching) temporal logic formula has been proposed for both the discrete [17,6] and the continuous time setting [4,8]. In this paper, we describe a prototype model checker for discrete and continuous-time Markov chains, the Erlangen Twente Markov Chain Checker (EMC2(E \vdash MC^2), where properties are expressed in appropriate extensions of CTL. We illustrate the general bene ts of this approach and discuss the structure of the tool. Furthermore we report on first successful applications of the tool to non-trivial examples, highlighting lessons learned during development and application of (EMC2(E \vdash MC^2)

    Flavor Neutrino Oscillations and Time-Energy Uncertainty Relation

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    We consider neutrino oscillations as non stationary phenomenon based on Schrodinger evolution equation and mixed states of neutrinos with definite flavors. We show that time-energy uncertainty relation plays a crucial role in neutrino oscillations. We compare neutrino oscillations with Bd0Bˉd0B_{d}^{0}\leftrightarrows\bar B_{d}^{0} oscillations.Comment: A report at the 2nd Scandinavian Neutrino Workshop, SNOW 2006, Stockholm, May 2-6, 200

    Interactive and automated application of virtual microscopy

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    Virtual microscopy can be applied in an interactive and an automated manner. Interactive application is performed in close association to conventional microscopy. It includes image standardization suitable to the performance of an individual pathologist such as image colorization, white color balance, or individual adjusted brightness. The steering commands have to include selection of wanted magnification, easy navigation, notification, and simple measurements (distances, areas). The display of the histological image should be adjusted to the physical limits of the human eye, which are determined by a view angle of approximately 35 seconds. A more sophisticated performance should include acoustic commands that replace the corresponding visual commands. Automated virtual microscopy includes so-called microscopy assistants which can be defined similar to the developed assistants in computer based editing systems (Microsoft Word, etc.). These include an automated image standardization and correction algorithms that excludes images of poor quality (for example uni-colored or out-of-focus images), an automated selection of the most appropriate field of view, an automated selection of the best magnification, and finally proposals of the most probable diagnosis. A quality control of the final diagnosis, and feedback to the laboratory determine the proposed system. The already developed tools of such a system are described in detail, as well as the results of first trials. In order to enhance the speed of such a system, and to allow further user-independent development a distributed implementation probably based upon Grid technology seems to be appropriate. The advantages of such a system as well as the present pathology environment and its expectations will be discussed in detail

    Beta decays with momentum space Majorana spinors

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    We construct and apply to beta decays a truly neutral local quantum field that is entirely based upon momentum space Majorana spinors. We make the observation that theory with momentum space Majorana spinors of real C parities is equivalent to Dirac's theory. For imaginary C parities, the neutrino mass can drop from the single beta decay trace and reappear in 0\nu \beta \beta, a curious and in principle experimentally testable signature for a non-trivial impact of Majorana framework in experiments with polarized sources.Comment: 7 pages, 1 figure; needs svjour.cls, svepj.cl

    Lack of Pregraduate Teaching on the Associations between the Built Environment, Physical Activity and Health in Swiss Architecture and Urban Design Degree Programs.

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    Lack of physical activity (PA) is the fourth risk factor for all-cause mortality. Regular PA reduces noncommunicable disease (NCD) and mortality risk. The built environment (BE) is a determinant of spontaneous daily PA. Professionals who plan and build the BE therefore affect public health. We tested the hypothesis of a lack of formal pregraduate training about associations between the BE, PA and health in architecture, landscape architecture, and urban design academic degree programs (DPs) in Switzerland. We reached out to all DPs in Switzerland to ask if and how these associations are taught. For those declaring to teach the topic, the program syllabus and course material were inspected. For 30 out of 33 identified programs, information for the analysis was obtained. A total of 18 declared teaching the BE, PA and health associations, but this could be confirmed for only 5 after verifying the course content. Teaching principles of building PA-promoting BE represents an underutilized potential for public health promotion. There is a need to introduce formal learning objectives in architecture, landscape architecture, and urban design DPs in Switzerland on the associations between BE, PA and health. It is likely that similar needs exist in other countries

    Grid computing in image analysis

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    Diagnostic surgical pathology or tissue–based diagnosis still remains the most reliable and specific diagnostic medical procedure. The development of whole slide scanners permits the creation of virtual slides and to work on so-called virtual microscopes. In addition to interactive work on virtual slides approaches have been reported that introduce automated virtual microscopy, which is composed of several tools focusing on quite different tasks. These include evaluation of image quality and image standardization, analysis of potential useful thresholds for object detection and identification (segmentation), dynamic segmentation procedures, adjustable magnification to optimize feature extraction, and texture analysis including image transformation and evaluation of elementary primitives
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