Regularity at infinity of real mappings and a Morse-Sard theorem

We prove a new Morse-Sard type theorem for the asymptotic critical values of semi-algebraic mappings and a new fibration theorem at infinity for $C^2$ mappings. We show the equivalence of three different types of regularity conditions which have been used in the literature in order to control the asymptotic behaviour of mappings. The central role of our picture is played by the $t$-regularity and its bridge toward the $\rho$-regularity which implies topological triviality at infinity

JPEG2000 image compression and visualization for desktop and mobile clients

This paper presents an architecture for JPEG2000 image compression and distribution using a Digital Rights Management (DRM) platform in the context of the PIMHAI project. The proposed architecture, based on a client-server interaction, will allow the users to upload images in PCIDSK database (PIX) format using a web-application front-end, and to perform the lossless JPEG2000 compression of such images. The resulting JPEG2000 images are then protected using cryptographic techniques and its intellectual property rights are managed digitally. In the context of the PIMHAI project, the proposed architecture will allow the storage of smaller and cryptographically protected image files in the database. The user access rights enforcement will prevent the access to the images by non authorized users. Another important feature is the decreasing of the connection time in the mobile client, through the expensive and slower wireless channel, to access the images in the database.info:eu-repo/semantics/acceptedVersio

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

Fluctuating local moments, itinerant electrons and the magnetocaloric effect: the compositional hypersensitivity of FeRh

We describe an ab-initio Disordered Local Moment Theory for materials with quenched static compositional disorder traversing first order magnetic phase transitions. It accounts quantitatively for metamagnetic changes and the magnetocaloric effect. For perfect stoichiometric B2-ordered FeRh, we calculate the transition temperature of the ferromagnetic-antiferromagnetic transition to be $T_t =$ 495K and a maximum isothermal entropy change in 2 Tesla of $|\Delta S|= 21.1$ J~K$^{-1}$~kg$^{-1}$. A large (40\%) component of $|\Delta S|$ is electronic. The transition results from a fine balance of competing electronic effects which is disturbed by small compositional changes - e.g. swapping just 2\% Fe of `defects' onto the Rh sublattice makes $T_t$ drop by 290K. This hypersensitivity explains the narrow compositional range of the transition and impurity doping effects.Comment: 11 pages, 4 figure

Metallic magnetism at finite temperatures studied by relativistic disordered moment description: Theory and applications

We develop a self-consistent relativistic disordered local moment (RDLM) scheme aimed at describing finite temperature magnetism of itinerant metals from first principles. Our implementation in terms of the Korringa--Kohn--Rostoker multiple scattering theory and the coherent potential approximation allows to relate the orientational distribution of the spins to the electronic structure, thus a self-consistent treatment of the distribution is possible. We present applications for bulk bcc Fe, L1$_0$-FePt and FeRh ordered in the CsCl structure. The calculations for Fe show significant variation of the local moments with temperature, whereas according to the mean field treatment of the spin fluctuations the Curie temperature is overestimated. The magnetic anisotropy of FePt alloys is found to depend strongly on intermixing between nominally Fe and Pt layers, and it shows a power-law behavior as a function of magnetization for a broad range of chemical disorder. In case of FeRh we construct a lattice constant vs. temperature phase diagram and determine the phaseline of metamagnetic transitions based on self-consistent RDLM free energy curves.Comment: 11 pages, 8 figure

Envisat products secure browsing in mobile clients using JPEG2000 interactivity protocol

Taking advantage of the mobile platforms to interact with the HICOD2000 system has been the motivation for the work described in this paper. Regardless of the limited resources available in mobile platforms the authors demonstrate that using the features of the HICOD2000 system the mobile device might be of major assistance in the field where satellite imagery may have an important and useful role. This paper describes an extension of the HICOD2000 system, available to the public through the ESA Service Support Environment. The EO JPEG2000 compressed products have achieved good compression ratios, minimizing both storage space and bandwidth. Regarding security to sensitive data the system enforces user access rights via a digital rights management platform called OpenSDRM. The mobile device has been endowed with the implementation of the JPIP protocol to optimize network bandwidth as well as the necessary components to interface with the OpenSDRM platform and decode JPSEC protected images: the OpenSDRM wallet and the protection tool.info:eu-repo/semantics/publishedVersio

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