Half Quantization

A general dynamical system composed by two coupled sectors is considered. The initial time configuration of one of these sectors is described by a set of classical data while the other is described by standard quantum data. These dynamical systems will be named half quantum. The aim of this paper is to derive the dynamical evolution of a general half quantum system from its full quantum formulation. The standard approach would be to use quantum mechanics to make predictions for the time evolution of the half quantum initial data. The main problem is how can quantum mechanics be applied to a dynamical system whose initial time configuration is not described by a set of fully quantum data. A solution to this problem is presented and used, as a guideline to obtain a general formulation of coupled classical-quantum dynamics. Finally, a quantization prescription mapping a given classical theory to the correspondent half quantum one is presented.Comment: 20 pages, LaTex file, Substantially revised versio

Time dependent transformations in deformation quantization

We study the action of time dependent canonical and coordinate transformations in phase space quantum mechanics. We extend the covariant formulation of the theory by providing a formalism that is fully invariant under both standard and time dependent coordinate transformations. This result considerably enlarges the set of possible phase space representations of quantum mechanics and makes it possible to construct a causal representation for the distributional sector of Wigner quantum mechanics.Comment: 16 pages, to appear in the J. Math. Phy

Nucleation of cracks in a brittle sheet

We use molecular dynamics to study the nucleation of cracks in a two dimensional material without pre-existing cracks. We study models with zero and non-zero shear modulus. In both situations the time required for crack formation obeys an Arrhenius law, from which the energy barrier and pre-factor are extracted for different system sizes. For large systems, the characteristic time of rupture is found to decrease with system size, in agreement with classical Weibull theory. In the case of zero shear modulus, the energy opposing rupture is identified with the breakage of a single atomic layer. In the case of non-zero shear modulus, thermally activated fracture can only be studied within a reasonable time at very high strains. In this case the energy barrier involves the stretching of bonds within several layers, accounting for a much higher barrier compared to the zero shear modulus case. This barrier is understood within adiabatic simulations

Sensitivity of ATLAS to FCNC single top quark production

The anomalous production of single top quarks via flavour-changing neutral currents (FCNCs), u(c)+g -> t, is studied using the ATLAS detector at the Large Hadron Collider. Detector simulation is done using the fast simulation package ATLFAST. A number of important systematic effects have been addressed. Based on a cut-based analysis, we shows that, with 10 fb-1, ATLAS can observe such top FCNC interactions with 5 sigma significance if the anomalous coupling strengths are k_ug/Lambda=k_cg/Lambda >= 0.0120 $^{+0.0014}_{-0.0012}$ (sys.) TeV-1, or equivalently Br(t->ug)+Br(t->cg) >= 2.64 $^{+0.63}_{-0.54}$ (sys.) x 10^{-4}$. In terms of production cross section, such a discovery requires at least 13.7 pb of anomalous single top quark production. With this level of sensitivity, ATLAS will be able to test some models of new physics

The impact of sound in people's behaviour in outdoor settings: A study using virtual reality and eye-tracking

This paper presents an analysis of space perception and how visual cues, such as landmarks and sound, are perceived and impact people's behaviour while exploring a given outdoor space. The primary goal of the research is to investigate how auditory sensations and visual stimuli influence people's behaviour in outdoor built environments. Our technique compares people's perception of the built environment in different conditions: the real world and a replicated virtual world. As a case study, a university campus was used, and four experimental conditions were designed. The study followed a between-subjects design, and the data collection included gaze data acquired from an eye-tracking device as well as self-reports. The study concludes that sound influences human behaviour in such settings. More specifically conclusions are that: i) human behaviour in virtual replications of the real space, including both visual and sound stimuli, is tendentially more similar to human behaviour in the real world than in simulations omitting sound; and ii) there is a difference in human behaviour when people explore the same virtually replicated outdoor space, by varying the presence of sound. This study is particularly useful for researchers working on the comparison between human behaviour in virtual and real environments, related to visual and sound stimuli.info:eu-repo/semantics/publishedVersio

SP mountain data analysis

An analysis of synthetic aperture radar data of SP Mountain was undertaken to demonstrate the use of digital image processing techniques to aid in geologic interpretation of SAR data. These data were collected with the ERIM X- and L-band airborne SAR using like- and cross-polarizations. The resulting signal films were used to produce computer compatible tapes, from which four-channel imagery was generated. Slant range-to-ground range and range-azimuth-scale corrections were made in order to facilitate image registration; intensity corrections were also made. Manual interpretation of the imagery showed that L-band represented the geology of the area better than X-band. Several differences between the various images were also noted. Further digital analysis of the corrected data was done for enhancement purposes. This analysis included application of an MSS differencing routine and development of a routine for removal of relief displacement. It was found that accurate registration of the SAR channels is critical to the effectiveness of the differencing routine. Use of the relief displacement algorithm on the SP Mountain data demonstrated the feasibility of the technique

The relationship between ENSO and Paraná River flow

International audienceSeveral studies indicate that there is a relationship between the climatic variability in the South American continent and alterations of the position and intensity of the heat sources in the equatorial region. The El Niño phenomenon can influence the precipitation over some regions of South America such as the Brazilian Northeast, Amazonia, South of Brazil and Uruguay. Over 80% of Brazil's energy comes from hydropower, and decisions concerning future availability and pricing require forecasts of river flow, ideally several months in advance. In this work the relationship between the Paraná River flow and the ENSO (El Niño/Southern Oscillation) mode is investigated and statistical forecasts of river flow are tested. An evaluation of the relationship between the Pacific sea surface temperature and the Paraná River flow indicates an ENSO pattern over the equatorial Pacific. The time series of the ENSO mode obtained by applying principal components analysis on the sea surface temperature (SST) were used as predictors for the Paraná River flow forecast. Improvement in the model forecast skill is also obtained by considering the lagged river flow time series as a predictor

Road network design with space syntax in Vendas Novas

The city of Vendas Novas, Évora, Portugal, is crossed by a national road. Currently, 30.000 to 35.000 vehicles cross the city, of which more than 2.000 are heavy motor vehicles. Due to the negative effects of the high levels of traffic, the city council as long proposed an alternative route to Estrada Nacional 4. To better understand the effects of an alternative route to the city of Vendas Novas our study applies an axial map analysis to the city current road network system and the two proposals currently being studied by the local city council and national infrastructure management entity. Based on this analysis a new proposal was drawn by our team to optimize the diversion of traffic from the city centre. Through the application of an axial map analysis, in this study our team hoped to demonstrate and disseminate near the local city management entities the potential and validity of this tool to the current and future planning of cities and, in particular, road networks.info:eu-repo/semantics/publishedVersio