3,942 research outputs found
Flavor and chiral oscillations with Dirac wave packets
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
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
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
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 ), 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 )
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Dopamine, time perception, and future time perspective.
RationaleImpairment in time perception, a critical component of decision-making, represents a risk factor for psychiatric conditions including substance abuse. A therapeutic that ameliorates this impairment could be advantageous in the treatment of impulsivity and decision-making disorders.ObjectivesHere we hypothesize that the catechol-O-methyltransferase (COMT) inhibitor tolcapone, which increases dopamine tone in frontal cortex (Ceravolo et al Synapse 43:201-207, 2002), improves time perception, with predictive behavioral, genetic, and neurobiological components.MethodsSubjects (n = 66) completed a duration estimation task and other behavioral testing in each of two sessions after receiving a single oral dose of tolcapone (200 mg) or placebo in randomized, double-blind, counterbalanced, crossover fashion. Resting state fMRI data were obtained in a subset of subjects (n = 40). Subjects were also genotyped for the COMT (rs4680) polymorphism.ResultsTime perception was significantly improved across four proximal time points ranging from 5 to 60 s (T(524) = 2.04, p = 0.042). The degree of this improvement positively correlated with subjective measures of stress, depression, and alcohol consumption and was most robust in carriers of the COMT Val158 allele. Using seed regions defined by a previous meta-analysis (Wiener et al Neuroimage 49:1728-1740, 2010), we found not only that a connection from right inferior frontal gyrus (RIFG) to right putamen decreases in strength on tolcapone versus placebo (p < 0.05, corrected), but also that the strength of this decrease correlates inversely with the increase in duration estimation on tolcapone versus placebo (r = - 0.37, p = 0.02).ConclusionsCompressed time perception can be ameliorated by administration of tolcapone. Additional studies should be conducted to determine whether COMT inhibitors may be effective in treating decision-making disorders and addictive behaviors
Flavor Neutrino Oscillations and Time-Energy Uncertainty Relation
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
oscillations.Comment: A report at the 2nd Scandinavian Neutrino Workshop, SNOW 2006,
Stockholm, May 2-6, 200
Interactive and automated application of virtual microscopy
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
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.
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
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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