Space-contained conflict revision, for geographic information

Using qualitative reasoning with geographic information, contrarily, for instance, with robotics, looks not only fastidious (i.e.: encoding knowledge Propositional Logics PL), but appears to be computational complex, and not tractable at all, most of the time. However, knowledge fusion or revision, is a common operation performed when users merge several different data sets in a unique decision making process, without much support. Introducing logics would be a great improvement, and we propose in this paper, means for deciding -a priori- if one application can benefit from a complete revision, under only the assumption of a conjecture that we name the "containment conjecture", which limits the size of the minimal conflicts to revise. We demonstrate that this conjecture brings us the interesting computational property of performing a not-provable but global, revision, made of many local revisions, at a tractable size. We illustrate this approach on an application.Comment: 14 page

Metallic properties of magnesium point contacts

We present an experimental and theoretical study of the conductance and stability of Mg atomic-sized contacts. Using Mechanically Controllable Break Junctions (MCBJ), we have observed that the room temperature conductance histograms exhibit a series of peaks, which suggests the existence of a shell effect. Its periodicity, however, cannot be simply explained in terms of either an atomic or electronic shell effect. We have also found that at room temperature, contacts of the diameter of a single atom are absent. A possible interpretation could be the occurrence of a metal-to-insulator transition as the contact radius is reduced, in analogy with what it is known in the context of Mg clusters. However, our first principle calculations show that while an infinite linear chain can be insulating, Mg wires with larger atomic coordinations, as in realistic atomic contacts, are alwaysmetallic. Finally, at liquid helium temperature our measurements show that the conductance histogram is dominated by a pronounced peak at the quantum of conductance. This is in good agreement with our calculations based on a tight-binding model that indicate that the conductance of a Mg one-atom contact is dominated by a single fully open conduction channel.Comment: 14 pages, 5 figure

Statistical fluctuations of the parametric derivative of the transmission and reflection coefficients in absorbing chaotic cavities

Motivated by recent theoretical and experimental works, we study the statistical fluctuations of the parametric derivative of the transmission T and reflection R coefficients in ballistic chaotic cavities in the presence of absorption. Analytical results for the variance of the parametric derivative of T and R, with and without time-reversal symmetry, are obtained for both asymmetric and left-right symmetric cavities. These results are valid for arbitrary number of channels, in completely agreement with the one channel case in the absence of absorption studied in the literature.Comment: Modified version as accepted in PR

Contribution to the study of Normandina pulchella: a cytological approach

A cytological study was undertaken on Normandina pulchella (Borr.) Nyl. in order to contribute to a better knowledge of the structure of the lichen and to acquire useful information on its taxonomic arrangement. Micro- and submicroscopic observations revealed that the tallus is heteromerous, with a medullary "tissue" composed of a network of hyaline fungal threads surrounding small clumps of algal cells. These were thick-walled and exhibited a single lobate chloroplast in which a conspicuous rnetameric pyrenoid, small starch granules and lipophilic plastoglobuli were frequently present. The mycobiont had hyphae with simple perforated septa with associated Woronin bodies. The relationship between the two partners was merely of very close proximity of their cell walls and involved no fungal penetration into algal cells. The presence of Woronin bodies, exclusive of the Ascomycetes and of plastoglobuli, that were described only in the Chlorococcales phycobionts in ascolichens, indicates that in all likelyhood Normandina is a member of the ascolichens and not of basidiolichens, as previously reported by some workers.Contribución al estudio de Normandina pulchella: aproximación citológica. Para contribuir a un mejor conocimiento de la estructura de Normandina pulchella (Borr.) Nyl. y para obtener informaciones útiles para su correcta colocación taxonómica, se ha emprendido un estudio citológico sobre el liquen. Observaciones al microscopio Óptico y electrónico han revelado que el tallo del liquen es heterómero, con un tejido medular compuesto por un entrelazamiento de hifas hialinas de hongos, que rodean pequeños grupos de células algales. Éstas presentaban una pared gruesa y un cloroplast lobulado simple, en el cua1 frecuentemente estaban presentes un voluminoso pirenoide metamérico, pequeños granos de almidón y plastoglóbulos lipófilos. El micobionte tenía hifas con septos simples y corpúsculos de Woronin asociados. La relación entre los dos componentes consistia en una simple y densa aproximación de sus paredes, sin una penetración del hongo en las células algales. La presencia de los corpúsculos de Woronin, exclusivos de 10s Ascomicetes y de 10s plastoglóbulos, que han sido descritos solo en los clorococales ficobiontes de 10s ascolíquenes indica que, con toda probabilidad, Normandina es un miembro de los ascolíquenes y no de los basidiolíquenes, como había sido previamente afirmado por algunos autores

Wavelet analysis of beam-soil structure response for fast moving train

This paper presents a wavelet based approach for the vibratory analysis of beam-soil structure related to a point load moving along a beam resting on the surface. The model is represented by the Euler-Bernoulli equation for the beam, elastodynamic equation of motion for the soil and appropriate boundary conditions. Two cases are analysed: the model with a half space under the beam and the model where the supporting medium has a finite thickness. Analytical solutions for the displacements are obtained and discussed in relation to the used boundary conditions and the type of considered loads: harmonic and constant. The analysis in time-frequency and velocity-frequency domains is carried out for realistic systems of parameters describing physical properties of the model. The approximate displacement values are determined by applying a wavelet method for a derivation of the inverse Fourier transform. A special form of the coiflet filter used in numerical calculations allows to carry out analysis without loss of accuracy related to singularities appearing in wavelet approximation formulas, when dealing with standard filters and complex dynamic systems. © 2009 IOP Publishing Ltd

Chaotic scattering with direct processes: A generalization of Poisson's kernel for non-unitary scattering matrices

The problem of chaotic scattering in presence of direct processes or prompt responses is mapped via a transformation to the case of scattering in absence of such processes for non-unitary scattering matrices, \tilde S. In the absence of prompt responses, \tilde S is uniformly distributed according to its invariant measure in the space of \tilde S matrices with zero average, < \tilde S > =0. In the presence of direct processes, the distribution of \tilde S is non-uniform and it is characterized by the average (\neq 0). In contrast to the case of unitary matrices S, where the invariant measures of S for chaotic scattering with and without direct processes are related through the well known Poisson kernel, here we show that for non-unitary scattering matrices the invariant measures are related by the Poisson kernel squared. Our results are relevant to situations where flux conservation is not satisfied. For example, transport experiments in chaotic systems, where gains or losses are present, like microwave chaotic cavities or graphs, and acoustic or elastic resonators.Comment: Added two appendices and references. Corrected typo