4,915 research outputs found

    Additional time-dependent phase in the flavor-conversion formulas

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    In the framework of intermediate wave-packets for treating flavor oscillations, we quantify the modifications which appear when we assume a strictly peaked momentum distribution and consider the second-order corrections in a power series expansion of the energy. By following a sequence of analytic approximations, we point out that an extra time-dependent phase is merely the residue of second-order corrections. Such phase effects are usually ignored in the relativistic wave-packet treatment, but they do not vanish non-relativistically and can introduce some small modifications to the oscillation pattern even in the ultra-relativistic limit.Comment: 9 pages, 3 figure

    A model checker for performance and dependability properties

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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 [8] and the continuous time setting [1], [3]. In this short paper, we describe the prototype model checker EāŠ¢MC2E \vdash M C^2 for discrete and continuous-time Markov chains, where properties are expressed in appropriate extensions of CTL.We illustrate the general benefits of this approach and discuss the structure of the tool

    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 EƎMC2, 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 EƎMC2

    The Effect of adhesive coatings on the microbial barrier properties of porous medical packaging materials

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    The most important characteristic for porous medical packaging is the ability to keep devices free from microorganisms from the point of sterilization to the point of use. Downstream converting processes can affect the properties of a package material. One of the most common converting steps is the addition of an adhesive coating. The current test standard for measuring the ability of a porous barrier material to serve as a microbial barrier is ASTM 1608-95. This test method was used to measure the microbial barrier properties of a wide selection of packaging materials in both their coated and uncoated forms. The test matrix consisted of five converters, eight medical device manufacturers, three sterilization methods, five aging cycles, and three package styles - pouches, lidded trays and form fill seal packages. The results were analyzed to compare the microbial barrier properties of a given material in its uncoated state versus its coated state and also to compare differences in microbial barrier properties of different porous packaging materials

    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 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 (EāŠ¢MC2(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 (EāŠ¢MC2(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 Bd0ā‡†BĖ‰d0B_{d}^{0}\leftrightarrows\bar B_{d}^{0} oscillations.Comment: A report at the 2nd Scandinavian Neutrino Workshop, SNOW 2006, Stockholm, May 2-6, 200

    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

    Service life evaluation of rigid explosive transfer lines

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    This paper describes a joint Army/NASA-sponsored research program on the service life evaluation of rigid explosive transfer lines. These transfer lines are used to initiate emergency crew escape functions on a wide variety of military and NASA aircraft. The purpose of this program was to determine quantitatively the effects of service, age, and degradation on rigid explosive transfer lines to allow responsible, conservative, service life determination. More than 800 transfer lines were removed from the U.S. Army AH-1G and AH-1S, the U.S. Air Force B-1 and F-111, and the U.S. Navy F-14 aircraft for testing. The results indicated that the lines were not adversely affected by age, service, or a repeat of the thermal qualification tests on full-service lines. Extension of the service life of rigid explosive transfer lines should be considered, since considerable cost savings could be realized with no measurable decrease in system reliability
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