Comment on "Theory of tailoring sonic devices: Diffraction dominates over refraction"

Recently N. Garcia et al. (Phys. Rev. E 67, 046606 (2003)) theoretically studied several acoustic devices with dimensions on de order of several wavelenghts. The authors discussed on experimental results previously reported by several of us (F. Cervera et al., Phys. Rev. Lett. 88, 023902 (2002)). They concluded that diffraction and not refraction is the ominating mechanism that explain the focusing effects observed in those experiments. In this Comment we reexamined their calculations and discussed why some of their interpretations of our results are misleading.Comment: 2 pages, 2 figures, a comment on an articl

Determining Neutrino Mass Hierarchy by Precision Measurements in Electron and Muon Neutrino Disappearance Experiments

Recently a new method for determining the neutrino mass hierarchy by comparing the effective values of the atmospheric \Delta m^2 measured in the electron neutrino disappearance channel, \Delta m^2(ee), with the one measured in the muon neutrino disappearance channel, \Delta m^2(\mu \mu), was proposed. If \Delta m^2(ee) is larger (smaller) than \Delta m^2(\mu \mu) the hierarchy is of the normal (inverted) type. We re-examine this proposition in the light of two very high precision measurements: \Delta m^2(\mu \mu) that may be accomplished by the phase II of the Tokai-to-Kamioka (T2K) experiment, for example, and \Delta m^2(ee) that can be envisaged using the novel Mossbauer enhanced resonant \bar\nu_e absorption technique. Under optimistic assumptions for the systematic uncertainties of both measurements, we estimate the parameter region of (\theta_13, \delta) in which the mass hierarchy can be determined. If \theta_13 is relatively large, sin^2 2\theta_13 \gsim 0.05, and both of \Delta m^2(ee) and \Delta m^2(\mu \mu) can be measured with the precision of \sim 0.5 % it is possible to determine the neutrino mass hierarchy at > 95% CL for 0.3 \pi \lsim \delta \lsim 1.7 \pi for the current best fit values of all the other oscillation parameters.Comment: 12 pages, 6 postscript figure

Visual control through narrow passages for an omnidirectional wheeled robot

Robotic systems are gradually replacing human intervention in dangerous facilities to improve human safety and prevent risky situations. In this domain, our work addresses the problem of autonomous crossing narrow passages in a semi-structured (i.e., partially-known) environment. In particular, we focus on the CERN’s Super Proton Synchrotron particle accelerator, where a mobile robot platform is equipped with a lightweight arm to perform measurements, inspection, and maintenance operations. The proposed approach leverages an image-based visual servoing strategy that exploits computer vision to detect and track known geometries defining narrow passage gates. The effectiveness of the proposed approach has been demonstrated in a realistic mock-up

Low prostaglandin E2 and cyclooxygenase expression in nasal mucosa fibroblasts of aspirin-intolerant asthmatics.

Background and objective: Anomalies in the regulation of cyclooxygenase (COX)-1 and-2 have been described in nasal polyps of aspirin-induced asthma (AIA). Whether these anomalies are specific to nasal polyps or affect all the nasal mucosa (NM) of upper airways is still unclear. The objective of this study was to compare the COX pathway in NM of AIA patients with the NM of control subjects. Methods: Fibroblasts were isolated from NM of 5 AIA patients (AIA-NM) and 5 control subjects (control-NM). Cells were treated with 10 ng/ml IL-1b for up to 72 hours. Prostaglandin E2 (PGE2) production was measured by ELISA, expression of COX-1 protein by Western blot, and COX-2 protein by ELISA, Western blot and immunofluorescence techniques. Results: IL-1b increased PGE2 production and COX-1 protein expression in control-NM fibroblasts, but no changes were found in AIA-NM. IL-1b provoked a significant timedependent increase in COX-2 protein expression in control-NM fibroblasts but had a very mild effect on COX-2 protein expression in AIA-NM. Conclusions: Our data suggest that abnormalities in the COX pathway are not a phenomenon exclusive to nasal polyp mucosa as they are also present in all the nasal mucosa of AIA patients. These anomalies may be involved in the pathogenesis of airway inflammation and NSAID intolerance in asthma patients with chronic rhinosinusitis and nasal polyposis

Analytic Approximations for Three Neutrino Oscillation Parameters and Probabilities in Matter

The corrections to neutrino mixing parameters in the presence of matter of constant density are calculated systematically as series expansions in terms of the mass hierarchy \dm{21}/\dm{31}. The parameter mapping obtained is then used to find simple, but nevertheless accurate formulas for oscillation probabibilities in matter including CP-effects. Expressions with one to one correspondence to the vacuum case are derived, which are valid for neutrino energies above the solar resonance energy. Two applications are given to show that these results are a useful and powerful tool for analytical studies of neutrino beams passing through the Earth mantle or core: First, the ``disentanglement problem'' of matter and CP-effects in the CP-asymmetry is discussed and second, estimations of the statistical sensitivity to the CP-terms of the oscillation probabilities in neutrino factory experiments are presented.Comment: 17 pages, 3 figure

El comportamiento post-critico de las vigas de acero armadas con chapas delgadas

An advance of expositions concerning the method of ultimate strength or post-critical strength of steel beams reinforced with thin plates is presented. This method is being object of experimental researches at the Applied Mechanics and Structures Institute (IMAE) of the Mathematics and Engineering Faculty, National University, Rosario (Argentina).Se presenta un avance de planteamientos relativos al método de la resistencia última o resistencia post-crítica de vigas de acero armadas con chapas delgadas, el cual está siendo objeto de investigaciones experimentales en el Instituto de Mecánica Aplicada y Estructuras (IMAE) de la Facultad de Ciencias Exactas e Ingeniería de la Universidad Nacional de Rosario (República Argentina)