Growth of homopolymer chain

Thermodynamic and kinetic properties of an homopolymer chain, in two dimensional square lattice, are studied by the use of chain growth algorithm based on the self avoiding walks process. Which is in accord with what happen in nature. All monomers are considered to be hydrophobic. In the thermodynamical study we examine the critical behaviour of the chain by following the evolution of the chain geometry with temperature. This is done by studying the behaviour of the mean distance R chosen to describe the homopolymer structure. Moreover, we give the behaviour of thermodynamic quantities such as conformational energy and specific heat. The effect of a force applied, in a fixed direction, on the chain when it is growing is also investigated. Finally, in a kinetic study, we analyse the evolution with temperature of the mean time necessarily for a given conformation to reach its native state.Thermodynamic and kinetic properties of an homopolymer chain, in two dimensional square lattice, are studied by the use of chain growth algorithm based on the self avoiding walks process. Which is in accord with what happen in nature. All monomers are considered to be hydrophobic. In the thermodynamical study we examine the critical behaviour of the chain by following the evolution of the chain geometry with temperature. This is done by studying the behaviour of the mean distance R chosen to describe the homopolymer structure. Moreover, we give the behaviour of thermodynamic quantities such as conformational energy and specific heat. The effect of a force applied, in a fixed direction, on the chain when it is growing is also investigated. Finally, in a kinetic study, we analyse the evolution with temperature of the mean time necessarily for a given conformation to reach its native state

Mean field study of decorated ferrimagnetic Ising model

The magnetic properties of a decorated ferrimagnetic Ising model consisting of two magnetic atoms A and B with spins σA= 1/2 and SB=1 are investigated by the use of the mean field approximation. Transition temperatures and the existence of the one or double compensation temperatures of the decorated ferrimagnetic square lattice are examined.The magnetic properties of a decorated ferrimagnetic Ising model consisting of two magnetic atoms A and B with spins σA= 1/2 and SB=1 are investigated by the use of the mean field approximation. Transition temperatures and the existence of the one or double compensation temperatures of the decorated ferrimagnetic square lattice are examined

De la guerre au massacre - Le “crime” d’inhumanité au milieu du XVIe siècle français

Se o massacre é um tratado de história de humanidade, parece que, no contexto dos conflitos religiosos da França do século XVI, o recurso ao massacre se tornou objecto de repulsa, apesar de muito praticado. A partir da análise do dossiê do processo contra os responsáveis do massacre dos Valdenses do Lubéron em 1551, este estudo mostra como o advogado do rei denunciou este “Crime de inumanidade”

Magnetic properties of spherical ferri-magnetic core/shells: A Monte Carlo study

In this work, we study the magnetic properties of a spherical ferrimagnetic core/shell, formed with nanoparticles of a spin-1/2 in the core surrounded by spin-1 in the shell layer. An external magnetic field is applied on this system. In addition, we examined the magnetizations as well as the susceptibilities of this system, for specific values of the coupling constants between the spins of the shell-shell Js, the core-shell Jp and core-core Jc. The response of the magnetization to the field is illustrated in the hysteresis loops

The Effect of Vacancy Defect and size on the double perovskite Sr2VMoO6: A Monte Carlo study

In this work, Monte Carlo simulations are performed to study the effect of vacancy defects on magnetic properties of a double perovskite Sr2VMoO6 film. The ions Mo5+ are modelized by  spins, whereas the ions V3+ are represented by S=1 spins. The vacancy concentration and the temperature effects are examined on the behavior of the magnetizations and susceptibilities for several system sizes.  From the obtained results, it is found that the increase of the defect concentration, decreases the magnitude of the magnetization, for a fixed system size. Also, we have studied the influence of an external and crystal fields on the critical behavior. Additionally, the response of the magnetization to the field shows a hysterisis behavior

Random crystal-field effect on magnetic materials

Using the mean field theory, we investigate the effect of the random crystal-field on both the spin-3/2 and spin-2 Blume-Capel models. Several new features are found including the apparence of new ordered phases at low temperature and consequently rich ground state phase diagrams. At finite temperature, new types of phase diagrams are found. Furthermore, we show that at low temperature, first-order transition lines are terminated by isolated critical points, between the ferromagnetic phases. We also discuss some interesting phenomena such as the existence of compensation and the existence of topologically different types of phase diagrams. The magnetic properties and phase diagrams of this model are presented. The obtained results confirm the existence of new ferri-magnetic phases and consequently the existence of new topologies for the different types of the phase diagrams. Indeed, these phase diagrams present rich varieties of phase transitions with first and second order phase transition lines. These lines are found to be linked by tri-critical points and terminated at isolated critical points. In the case of the spin-2 Blume-Capel model, the interesting finding to emerge consists in the appearance of a new phase, with magnetization (m=3/2), and consequently new types of phase diagrams, divided on topologies depending on the existence of the paramagnetic phase at temperature T=0 K. Finally, the thermal behaviour of the sub-lattices magnetizations, showed the presence of the compensation behaviours for negative values of the crystal-field.Using the mean field theory, we investigate the effect of the random crystal-field on both the spin-3/2 and spin-2 Blume-Capel models. Several new features are found including the apparence of new ordered phases at low temperature and consequently rich ground state phase diagrams. At finite temperature, new types of phase diagrams are found. Furthermore, we show that at low temperature, first-order transition lines are terminated by isolated critical points, between the ferromagnetic phases. We also discuss some interesting phenomena such as the existence of compensation and the existence of topologically different types of phase diagrams. The magnetic properties and phase diagrams of this model are presented. The obtained results confirm the existence of new ferri-magnetic phases and consequently the existence of new topologies for the different types of the phase diagrams. Indeed, these phase diagrams present rich varieties of phase transitions with first and second order phase transition lines. These lines are found to be linked by tri-critical points and terminated at isolated critical points. In the case of the spin-2 Blume-Capel model, the interesting finding to emerge consists in the appearance of a new phase, with magnetization (m=3/2), and consequently new types of phase diagrams, divided on topologies depending on the existence of the paramagnetic phase at temperature T=0 K. Finally, the thermal behaviour of the sub-lattices magnetizations, showed the presence of the compensation behaviours for negative values of the crystal-field

Le bucher dans le martyre protestant - tradition et invention d’après les martyrologes français et anglais du XVIe siècle

Nos reinos de França e de Inglaterra, um número muito significativo de Protestantes, cerca de um milhar, foram condenados à Pilha no século XVI. Estas execuções foram apresentadas como um novo martírio cristão. Este artigo analisa a maneira como a Reforma promoveu esta devoção extrema a partir da representação iconográfica da Pilha

Spectral Classification of a Set of Hyperspectral Images using the Convolutional Neural Network, in a Single Training

International audienceHyperspectral imagery has seen a great evolution in recent years. Consequently, several fields (medical, agriculture, geosciences) need to make the automatic classification of these hyperspectral images with a high rate and in an acceptable time. The state-of-the-art presents several classification algorithms based on the Convolutional Neural Network (CNN) and each algorithm is training on a part of an image and then performs the prediction on the rest. This article proposes a new Fast Spectral classification algorithm based on CNN, and which allows to build a composite image from multiple hyperspectral images, then trains the model only once on the composite image. After training, the model can predict each image separately. To test the validity of the proposed algorithm, two free hyperspectral images are taken, and the training time obtained by the proposed model on the composite image is better than the time obtained from the model of the state-of-the-art

XMCD studies and magnetic properties of ZnTe doped with Ti, Cr, Mn and Co

Using the full potential linear augmented plane wave (FP-LAPW) method as implemented in the WIEN2K code in connection with the Generalized Gradient Approximation (GGA). We study the magnetic properties of ZnTe doped with some transition metals elements. In addition, to the X-ray absorption spectra (XAS) and X-ray Magnetic circular dichroism (XMCD) calculations to compute the orbital and spin moments separately. Two principal examples will be given: The induced magnetic moments ZnTe of the light and heavy 3d elements (Ti, Cr and Mn, Co) can be determined by the XMCD sum rules analysis at the L2,3 edges. Moreover, it has been found that for the lighter 3d elements the spin-orbit splitting of the transitions 2P1/2 and 2P3/2 states reduces toward, which has a consequence that two excitations are coupled

Magnetization and ordering temperature of films and multilayers

We investigate, in this paper, a number of magnetic properties of single and multilayer thin film systems within the Ising model by application of mean field, finite cluster approximations as well as by Monte Carlo simulations. The magnetization profiles and the magnetic ordering temperature are calculated for different magnetic systems. The influence of corrugation and disorder at the surface, on the critical behavior of ferromagnetic Ising film is also studied. It is found that the critical surface exponent of the magnetization follows closely the one of a perfect surface, in the two cases: corrugated surface and random equiprobable coupling surface. However, in the case of flat surface with random interactions the surface critical exponent depends on the concentration of the strong interaction, while such critical exponent is independent on the concentration. Moreover, in the case of corrugated surface, the effective exponent for a given layer, is a function of the number of steps at the surface. The probability of a magnetic ground state is larger for low spatial dimensionality of an extended system, or lower for local symmetry of a given site in the atomic lattice. Consequently, the magnetic properties are usually more pronounced at the surface of a bulk magnet as compared to the bulk interior. The phase diagram and the characteristic behaviors of the surface magnetization, are investigated for amorphous or cristalline surfaces. Indeed, the size effects become more relevant at low temperature depending on film thickness.We investigate, in this paper, a number of magnetic properties of single and multilayer thin film systems within the Ising model by application of mean field, finite cluster approximations as well as by Monte Carlo simulations. The magnetization profiles and the magnetic ordering temperature are calculated for different magnetic systems. The influence of corrugation and disorder at the surface, on the critical behavior of ferromagnetic Ising film is also studied. It is found that the critical surface exponent of the magnetization follows closely the one of a perfect surface, in the two cases: corrugated surface and random equiprobable coupling surface. However, in the case of flat surface with random interactions the surface critical exponent depends on the concentration of the strong interaction, while such critical exponent is independent on the concentration. Moreover, in the case of corrugated surface, the effective exponent for a given layer, is a function of the number of steps at the surface. The probability of a magnetic ground state is larger for low spatial dimensionality of an extended system, or lower for local symmetry of a given site in the atomic lattice. Consequently, the magnetic properties are usually more pronounced at the surface of a bulk magnet as compared to the bulk interior. The phase diagram and the characteristic behaviors of the surface magnetization, are investigated for amorphous or cristalline surfaces. Indeed, the size effects become more relevant at low temperature depending on film thickness