Search results for "Homogeneous"
showing 10 items of 718 documents
Integrating Environmental Temperature Conditions into the SIR Model for Vector-Borne Diseases
2020
International audience; Nowadays, Complex networks are used to model and analyze various problems of real-life e.g. information diffusion in social networks, epidemic spreading in human population etc. Various epidemic spreading models are proposed for analyzing and understanding the spreading of infectious diseases in human contact networks. In classical epidemiological models, a susceptible person becomes infected after getting in contact with an infected person among the human population only. However, in vector-borne diseases, a human can be infected also by a living organism called a vector. The vector population that also help in spreading diseases is very sensitive to environmental f…
Mixed-aspect fractal surfaces
2013
In order to provide accurate tools to model original surfaces in a Computer Aided Geometric Design context, we develop a formalism based on iterated function systems. This model enables us to represent both smooth and fractal free-form curves and surfaces. But, because of the self-similarity property underlying the iterated function systems, curves and surfaces can only have homogeneous roughness. The aim of our work was to elaborate a method to build parametric shapes (curves, surfaces, ...) with a non-uniform local aspect: every point is assigned a ''geometric texture'' that evolves continuously from a smooth to a rough aspect. The principle is to blend shapes with uniform aspects to defi…
Chiralities of nodal points along high symmetry lines with screw rotation symmetry
2021
Screw rotations in nonsymmorphic space group symmetries induce the presence of hourglass and accordion shape band structures along screw invariant lines whenever spin-orbit coupling is nonnegligible. These structures induce topological enforced Weyl points on the band intersections. In this work we show that the chirality of each Weyl point is related to the representations of the cyclic group on the bands that form the intersection. To achieve this, we calculate the Picard group of isomorphism classes of complex line bundles over the 2-dimensional sphere with cyclic group action, and we show how the chirality (Chern number) relates to the eigenvalues of the rotation action on the rotation …
Fermionic transport and out-of-equilibrium dynamics in a homogeneous Hubbard model with ultracold atoms
2012
The transport measurements of an interacting fermionic quantum gas in an optical lattice provide a direct experimental realization of the Hubbard model—one of the central models for interacting electrons in solids—and give insights into the transport properties of many-body phases in condensed-matter physics.
Breaking of SU(4) symmetry and interplay between strongly correlated phases in the Hubbard model
2016
We study the thermodynamic properties of four-component fermionic mixtures described by the Hubbard model using the dynamical mean-field-theory approach. Special attention is given to the system with SU(4)-symmetric interactions at half filling, where we analyze equilibrium many-body phases and their coexistence regions at nonzero temperature for the case of simple cubic lattice geometry. We also determine the evolution of observables in low-temperature phases while lowering the symmetry of the Hamiltonian towards the two-band Hubbard model. This is achieved by varying interflavor interactions or by introducing the spin-flip term (Hund's coupling). By calculating the entropy for different s…
Three-mode two-boson Jaynes–Cummings model in trapped ions
2006
In this paper, we analyse a two-boson three-mode Jaynes–Cummings model which can be implemented in the context of trapped ions. The symmetries of the Hamiltonian are brought to light and analysed in detail in order to solve the eigenvalue problem. The calculation of the time evolution operator shows the possibility of realizing interesting applications, such as the generation of nonclassical states.
Solubility of Polymers
2011
Detailed knowledge concerning the phase state (homogeneous or coexistence of two or more condensed phases) of polymer containing mixtures is indispensible in virtually any area related to the production or application of macromolecules. In addition to this qualitative information it is for many purposes highly desirable to dispose of quantitative data regarding solvent quality or, more generally, with respect to the thermodynamic interaction between the components of the mixtures. This contribution starts with a brief presentation of the thermodynamic criteria deciding on the phase state and presents the experimental methods used in this area. The next section gives an overview on typical b…
Magnetic Exchange between Orbitally Degenerate Metal Ions: The Problem of Magnetic Anisotropy
2001
Abstract In this paper we show that a strong magnetic anisotropy appears in exchange mixed–valence clusters containing orbitally degenerate metal ions. Combining an effective Hamiltonian approach with the technique of the irreducible tensor operators (ITO) and pseudoangular momentum representation we have solved the problem of magnetic exchange in localized and delocalized (mixed–valence) systems with different overall symmetries ( D 2 h , D 3 h , D 4 h ). The energy pattern as well as the character of the magnetic anisotropy is closely related to the ground term of the ions, electron transfer pathways, and overall symmetry of the system being affected also by the local crystal fields, spin…
El asesoramiento genético en los déficits visuales y auditivos
2008
espanolObjetivo: Las enfermedades hereditarias que afectan a la retina y la audicion presentan una amplia heterogeneidad clinica y genetica. Durante la pasada decada se han producido importantes avances en el conocimiento de la patogenia molecular de estas enfermedades y, actualmente, mas de 200 genes y loci estan implicados en enfermedades de la retina y mas de 60 son responsables de perdida de audicion. Metodo: El estudio genetico molecular es crucial para confirmar el diagnostico clinico, permite, en ocasiones, conocer el pronostico de la enfermedad, un consejo genetico y reproductivo adecuado y permite la posibilidad de crear grupos de pacientes geneticamente homogeneos para futuros ens…
Repeatability of in vitro power profile measurements for multifocal contact lenses
2015
Abstract Purpose To evaluate the repeatability of an optical device (NIMO TR1504, Lambda-X, Belgium) for measuring multifocal contact lens power profiles. Methods The NIMO TR1504 was used to measure power profiles 30 times for each of 10 different contact lenses from 4 major companies. All contact lenses were labelled as −3 D for distance vision; half were for high addition and half for low addition. The optical zone in all measurements was set to 3-mm radius. For each lens, the median power profile and the residuals of the 30 measurements were calculated. The 95% confidence bands and two indices that summarize measurement errors were calculated: the repeatability limit and an index of repe…