Université de Sherbrooke

About: Université de Sherbrooke is a education organization based out in Sherbrooke, Quebec, Canada. It is known for research contribution in the topics: Population & Receptor. The organization has 14922 authors who have published 28783 publications receiving 792511 citations. The organization is also known as: Universite de Sherbrooke & Sherbrooke University.

Influence of temperature and pressure on the electronic transitions in SnS and SnSe semiconductors.

Abstract: Optical-absorption measurements in the near infrared have enabled us to determine the direct and indirect band gaps of SnS and SnSe layered compounds, in the a and b polarizations, at temperatures ranging from 7 to 295 K (at P=0 kbar) and pressures up to 40 kbar (at T=295 K) At T=295 K and P=0 kbar, we obtain, for SnS, ${\mathit{E}}_{\mathrm{ind}}$${\mathrm{i}}_{\mathrm{a}}$ a=1076 eV, ${\mathit{E}}_{\mathrm{ind}\mathbf{b}}$=1049 eV, and ${\mathit{E}}_{\mathrm{dir}}$ b=1296 eV; and for SnSe, ${\mathit{E}}_{\mathrm{ind}\mathbf{a}}$=0898 eV, ${\mathit{E}}_{\mathrm{ind}\mathbf{b}}$=0903 eV, ${\mathit{E}}_{\mathrm{dir}\mathbf{a}}$=1238 eV, and ${\mathit{E}}_{\mathrm{dir}\mathbf{b}}$=1047 eV For both crystals, an additional structure, associated with an impurity level, is observed in the a polarization Its shape reveals the three-dimensional nature of the electronic properties in these compounds The measured pressure coefficients for the transitions ${\mathit{E}}_{\mathrm{inda}}$, ${\mathit{E}}_{\mathrm{ind}\mathbf{b}}$, ${\mathit{E}}_{\mathrm{dir}\mathbf{a}}$, and ${\mathit{E}}_{\mathrm{dir}\mathbf{b}}$ are, for SnS, -56, -60, -83, and -73 meV/kbar, respectively; and for SnSe, -52, -89, -36, and -112 meV/kbar, respectively The corresponding temperature coefficients are, for SnS, -024, -036, (undetermined), and -0563 meV/K; and for SnSe, -032, -029, -043, and -043 meV/K The behavior of the transition energies with temperature is explained by a self-energy correction attributed to the interaction between electrons and nonpolar phonons Concerning this temperature dependence, we find that the effect of volume dilatation is opposite in sign to that of the electron-phonon interactions The latter effect dominates

Aging of the immune system: Focus on inflammation and vaccination

Abstract: Major advances in preventing, delaying, or curing individual pathologies are responsible for an increasingly long life span in the developed parts of our planet, and indeed reaching eight to nine decades of life is nowadays extremely frequent. However, medical and sanitary advances have not prevented or delayed the underlying cause of the disparate pathologies occurring in the elderly: aging itself. The identification of the basis of the aging processes that drives the multiple pathologies and loss of function typical of older individuals is a major challenge in current aging research. Among the possible causes, an impairment of the immune system plays a major role, and indeed numerous studies have described immunological changes which occur with age. Far from the intention of being exhaustive, this review will focus on recent advances and views on the role that modifications of cell signalling and remodelling of the immune response play during human aging and longevity, paying particular attention to phenomena which are linked to the so called inflammaging process, such as dysregulation of innate immunity, altered T-cell or B-cell maturation and differentiation, as well as to the implications of immune aging for vaccination strategies in the elderly.