3,059 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
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
Prognostic significance of endogenous adhesion/growth-regulatory lectins in lung cancer
Objective: To determine the expression of endogenous adhesion/growth-regulatory lectins and their binding sites using labeled tissue lectins as well as the binding profile of hyaluronic acid as an approach to define new prognostic markers. Methods: Sections of paraffin-embedded histological material of 481 lungs from lung tumor patients following radical lung excision processed by a routine immunohistochemical method (avidin-biotin labeling, DAB chromogen). Specific antibodies against galectins-1 and - 3 and the heparin-binding lectin were tested. Staining by labeled galectins and hyaluronic acid was similarly visualized by a routine protocol. After semiquantitative assessment of staining, the results were compared with the pT and pN stages and the histological type. Survival was calculated by univariate and multivariate methods. Results: Binding of galectin-1 and its expression tended to increase, whereas the parameters for galectin-3 decreased in advanced pT and pN stages at a statistically significant level. The number of positive cases was considerably smaller among the cases with small cell lung cancer than in the group with non-small-cell lung cancer, among which adenocarcinomas figured prominently with the exception of galectin-1 expression. Kaplan-Meier computations revealed that the survival rate of patients with galectin-3-binding or galectin-1-expressing tumors was significantly poorer than that of the negative cases. In the multivariate calculations of survival lymph node metastases ( p < 0.0001), histological type ( p = 0.003), galectin-3-binding capacity ( p = 0.01), galectin-3 expression ( p = 0.03) and pT status ( p = 0.003) proved to be independent prognostic factors, not correlated with the pN stage. Conclusion: The expression and the capacity to bind the adhesion/growth regulatory galectin-3 is defined as an unfavorable prognostic factor not correlated with the pTN stage. Copyright (C) 2005 S. Karger AG, Basel
Seeing Star Formation Regions with Gravitational Microlensing
We qualitatively study the effects of gravitational microlensing on our view
of unresolved extragalactic star formation regions. Using a general
gravitational microlensing configuration, we perform a number of simulations
that reveal that specific imprints of the star forming region are imprinted,
both photometrically and spectroscopically, upon observations. Such
observations have the potential to reveal the nature and size of these star
forming regions, through the degree of variability observed in a monitoring
campaign, and hence resolve the star formation regions in distant galaxies
which are too small to be probed via more standard techniques.Comment: 7 pages, 8 figures, ApJ accepte
Extended Source Diffraction Effects Near Gravitational Lens Fold Caustics
Calculations are presented detailing the gravitational lens diffraction due
to the steep brightness gradient of the limb of a stellar source. The lensing
case studied is the fold caustic crossing. The limb diffraction signal greatly
exceeds that due to the disk as a whole and should be detectable for white
dwarf sources in our Galaxy and it's satellites with existing telescopes.
Detection of this diffraction signal would provide an additional mathematical
constraint, reducing the degeneracy among models of the lensing geometry. The
diffraction pattern provides pico-arcsecond resolution of the limb profile.Comment: 19 pages including 17 figures, Accepted for publication in ApJ, Minor
conceptual change from previous versio
Semi-linear gravitational lens inversion
We describe a new method for analyzing gravitational lens images, for the
case where the source light distribution is pixelized. The method is suitable
for high resolution, high S/N data of a multiply-imaged extended source. For a
given mass distribution, we show that the step of inverting the image to obtain
the deconvolved pixelized source light distribution, and the uncertainties, is
a linear one. This means that the only parameters of the non-linear problem are
those required to model the mass distribution. This greatly simplifies the
search for a min.-chi^2 fit to the data and speeds up the inversion. The method
is extended in a straightforward way to include linear regularization. We apply
the method to simulated Einstein ring images and demonstrate the effectiveness
of the inversion for both the unregularized and regularized cases.Comment: to appear in Ap
Muonium-antimuonium conversion in models with heavy neutrinos
We study muonium-antimuonium conversion and mu+ e- to mu- e+ scattering
within two different lepton-flavor-violating models with heavy neutrinos: model
I is a typical seesaw that violates lepton number as well as flavor; model II
has a neutrino mass texture where lepton number is conserved. We look for the
largest possible amplitudes of these processes that are consistent with current
bounds. We find that model I has very limited chance of providing an observable
signal, except if a finely tuned condition in parameter space occurs. Model II,
on the other hand, requires no fine tuning and could cause larger effects.
However, the maximum amplitude provided by this model is still two orders of
magnitude below the sensitivity of current experiments: one predicts an
effective coupling G_MM up to 10^{-4}G_F for heavy neutrino masses near 10 TeV.
We have also clarified some discrepancies in previous literature on this
subject.Comment: 16 pages, 4 figures, reference adde
Diffusion with critically correlated traps and the slow relaxation of the longest wavelength mode
We study diffusion on a substrate with permanent traps distributed with
critical positional correlation, modeled by their placement on the perimeters
of a critical percolation cluster. We perform a numerical analysis of the
vibrational density of states and the largest eigenvalue of the equivalent
scalar elasticity problem using the method of Arnoldi and Saad. We show that
the critical trap correlation increases the exponent appearing in the stretched
exponential behavior of the low frequency density of states by approximately a
factor of two as compared to the case of no correlations. A finite size scaling
hypothesis of the largest eigenvalue is proposed and its relation to the
density of states is given. The numerical analysis of this scaling postulate
leads to the estimation of the stretch exponent in good agreement with the
density of states result.Comment: 15 pages, LaTeX (RevTeX
Virtual slides in peer reviewed, open access medical publication
<p>Abstract</p> <p>Background</p> <p>Application of virtual slides (VS), the digitalization of complete glass slides, is in its infancy to be implemented in routine diagnostic surgical pathology and to issues that are related to tissue-based diagnosis, such as education and scientific publication.</p> <p>Approach</p> <p>Electronic publication in Pathology offers new features of scientific communication in pathology that cannot be obtained by conventional paper based journals. Most of these features are based upon completely open or partly directed interaction between the reader and the system that distributes the article. One of these interactions can be applied to microscopic images allowing the reader to navigate and magnify the presented images. VS and interactive Virtual Microscopy (VM) are a tool to increase the scientific value of microscopic images.</p> <p>Technology and Performance</p> <p>The open access journal Diagnostic Pathology <url>http://www.diagnosticpathology.org</url> has existed for about five years. It is a peer reviewed journal that publishes all types of scientific contributions, including original scientific work, case reports and review articles. In addition to digitized still images the authors of appropriate articles are requested to submit the underlying glass slides to an institution (DiagnomX.eu, and Leica.com) for digitalization and documentation. The images are stored in a separate image data bank which is adequately linked to the article. The normal review process is not involved. Both processes (peer review and VS acquisition) are performed contemporaneously in order to minimize a potential publication delay. VS are not provided with a DOI index (digital object identifier). The first articles that include VS were published in March 2011.</p> <p>Results and Perspectives</p> <p>Several logistic constraints had to be overcome until the first articles including VS could be published. Step by step an automated acquisition and distribution system had to be implemented to the corresponding article. The acceptance of VS by the reader is high as well as by the authors. Of specific value are the increased confidence to and reputation of authors as well as the presented information to the reader. Additional associated functions such as access to author-owned related image collections, reader-controlled automated image measurements and image transformations are in preparation.</p> <p>Virtual Slides</p> <p>The virtual slide(s) for this article can be found here: <url>http://www.diagnosticpathology.diagnomx.eu/vs/1232133347629819</url>.</p
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