Superconductivity close to the charge-density-wave instability

We use the weak coupling renormalization group method to examine the interplay between charge-density-wave and s-wave superconducting orders in a quasi-one-dimensional model of electrons interacting with acoustic phonons. The relative stability of both types of order is mapped out at arbitrary nesting deviations and Debye phonon frequency $\omega_D$. We singled out a power law increase of the superconducting $T_c\sim \omega_D^{0.7}$ from a quantum critical point of charge-density-wave order triggered by nesting alterations. The results capture the key features shown by the proximity between the two types of ordering in the phase diagram of the recently discovered Perylene based organic superconductor under pressure. The impact of Coulomb interaction on the relative stability of the competing phases is examined and discussed in connection with the occurrence of s-wave superconductivity in low dimensional charge-density-wave materials.Comment: 6 pages, 5 figure

Critical Properties and Exchange Interactions of Antiferromagnetic A-spinel Lattice: A Study Through High-temperature Series Expansions

We derive high- temperature series expansions for the spin correlation functions of the A-spinel lattice. The development is extended to the order 6 in β = 1/KBT with nearest-neighbour and next-nearest neighbour interactions. The results are given for various neighbour correlation functions (up to the third). The behaviour with the temperature is presented. The critical region is studied by applying the Padé approximants method to the corresponding high- temperature series expansion of the magnetic susceptibility and the correlation length. The approach is applied to the experimental results of the particular system A-spinel CoCo2O4 . The following estimates are obtained for the familiar critical exponents:  γ =  1.382±0.010 and ν =  0.701±0.012.We derive high- temperature series expansions for the spin correlation functions of the A-spinel lattice. The development is extended to the order 6 in β = 1/KBT with nearest-neighbour and next-nearest neighbour interactions. The results are given for various neighbour correlation functions (up to the third). The behaviour with the temperature is presented. The critical region is studied by applying the Padé approximants method to the corresponding high- temperature series expansion of the magnetic susceptibility and the correlation length. The approach is applied to the experimental results of the particular system A-spinel CoCo2O4 . The following estimates are obtained for the familiar critical exponents:  γ =  1.382±0.010 and ν =  0.701±0.012

A review on estimation methods of NonLinear Mixed Effects model with Stochastic Differential Equations, application to threedimensional Ornstein-Uhlenbeck process.

In this paper, we focus on estimation methods for non-linear mixed effects (NLME) models with stochasticdifferential equations (SDEs). This type of model is very useful in multidisciplinary research since it allows toadequately model different phenomena by taking into account their dynamic sides based the two mainingredients: stochastic differential equations and the random effects. As a result, it is possible to take intoaccount different factors that would otherwise be difficult to include in the model. The resulting modelling isfurther enhanced by the population approach where we consider a whole population of subjects simultaneouslyrather than a single individual as in the standard approaches. With these advantages in mind, it becomesobvious that that there is a need for both theoretical and practical tools for manipulate such models.Unfortunately, statistical inference in this area remains a complicated task, whereas it seems useful to make anoverview of the current state of knowledge on various existing methods which have proven to be most fruitfuland effective. Therefore, we introduce these different methods according to the different issues related to thistype of modelling, depending on the availability of the density of transitions in explicit form and the existence ornot of measurement noise when the process is observed directly or indirectly. Finally, we illustrate this reviewof estimation methods for non-linear SDME models by the implementation of a simulation study and estimationof the three-dimensional Ornstein-Uhlenbeck process (OU), in its multidimensional and stochastic version

Critical phenomena in ferromagnetic superlattices

Within the framework of the high-temperature series expansions technique, we examine the phase transition and the critical phenomena of a two-component superlattice with simple cubic structure, through three models: Ising, XY and Heisenberg. The reduced critical temperature of the system is studied as a function of the thickness of the constituents and the exchange interactions in each material, and within the interface. We show the existence of a critical thickness of the unit cell at which the reduced critical temperature of the binary superlattice remains insensitive to the exchange coupling within the interfaces. The values of the effective critical exponent γ eff associated with the magnetic susceptibility agreed with the universal classes in the limit cases where the superlattice is still comparable to an infinite simple cubic lattice. We attribute the breakdown in the universality hypothesis to the crossover effects. Copyright EDP Sciences/Società Italiana di Fisica/Springer-Verlag 2005

Critical Properties and Exchange Interactions of Antiferromagnetic A-spinel Lattice: A Study Through High-temperature Series Expansions.

We derive high- temperature series expansions for the spin correlation functions of the A-spinel lattice. The development is extended to the order 6 in 1 with nearest-neighbour and next-nearest neighbour interactions. The β = kBT results are given for various neighbour correlation functions (up to the third). The behaviour with the temperature is presented. The critical region is studied by applying the Padé approximants method to the corresponding high- temperature series expansion of the magnetic susceptibility and the correlation length. The approach is applied to the experimental results of the particular system A-spinel CoCo2O4. The following estimates are obtained for the familiar critical exponents: γ = 1. 382 ± 0. 010 and ν = 0. 701

Phytochemical Compounds and Nanoparticles as Phytochemical Delivery Systems for Alzheimer’s Disease Management

Alzheimer’s disease remains one of the most widespread neurodegenerative reasons for dementia worldwide and is associated with considerable mortality and morbidity. Therefore, it has been considered a priority for research. Indeed, several risk factors are involved in the complexity of the therapeutic ways of this pathology, including age, traumatic brain injury, genetics, exposure to aluminum, infections, diabetes, vascular diseases, hypertension, dyslipidemia, and obesity. The pathophysiology of Alzheimer’s disease is mostly associated with hyperphosphorylated protein in the neuronal cytoplasm and extracellular plaques of the insoluble β-amyloid peptide. Therefore, the management of this pathology needs the screening of drugs targeting different pathological levels, such as acetylcholinesterase (AchE), amyloid β formation, and lipoxygenase inhibitors. Among the pharmacological strategies used for the management of Alzheimer’s disease, natural drugs are considered a promising therapeutic strategy. Indeed, bioactive compounds isolated from different natural sources exhibit important anti-Alzheimer effects by their effectiveness in promoting neuroplasticity and protecting against neurodegeneration as well as neuroinflammation and oxidative stress in the brain. These effects involve different sub-cellular, cellular, and/or molecular mechanisms, such as the inhibition of acetylcholinesterase (AchE), the modulation of signaling pathways, and the inhibition of oxidative stress. Moreover, some nanoparticles were recently used as phytochemical delivery systems to improve the effects of phytochemical compounds against Alzheimer’s disease. Therefore, the present work aims to provide a comprehensive overview of the key advances concerning nano-drug delivery applications of phytochemicals for Alzheimer’s disease management