University of Montpellier

About: University of Montpellier is a education organization based out in Montpellier, Languedoc-Roussillon, France. It is known for research contribution in the topics: Population & Context (language use). The organization has 26816 authors who have published 53843 publications receiving 1646905 citations. The organization is also known as: Université de Montpellier.

Shear strength properties of wet granular materials.

Abstract: We investigate shear strength properties of wet granular materials in the pendular state (i.e., the state where the liquid phase is discontinuous) as a function of water content. Sand and glass beads were wetted and tested in a direct shear cell and under various confining pressures. In parallel, we carried out three-dimensional molecular dynamics simulations by using an explicit equation expressing capillary force as a function of interparticle distance, water bridge volume, and surface tension. We show that, due to the peculiar features of capillary interactions, the major influence of water content over the shear strength stems from the distribution of liquid bonds. This property results in shear strength saturation as a function of water content. We arrive at the same conclusion by a microscopic analysis of the shear strength. We propose a model that accounts for the capillary force, the granular texture, and particle size polydispersity. We find fairly good agreement of the theoretical estimate of the shear strength with both experimental data and simulations. From numerical data, we analyze the connectivity and anisotropy of different classes of liquid bonds according to the sign and level of the normal force as well as the bond direction. We find that weak compressive bonds are almost isotropically distributed whereas strong compressive and tensile bonds have a pronounced anisotropy. The probability distribution function of normal forces is exponentially decreasing for strong compressive bonds, a decreasing power-law function over nearly one decade for weak compressive bonds, and an increasing linear function in the range of tensile bonds. These features suggest that different bond classes do not play the same role with respect to the shear strength.

Effect of methotrexate, anti-tumor necrosis factor α, and rituximab on the immune response to influenza and pneumococcal vaccines in patients with rheumatoid arthritis: a systematic review and meta-analysis.

Abstract: Objective To assess the current literature on the impact of rheumatoid arthritis (RA) treatments on the humoral response to pneumococcal and influenza vaccines Methods We systematically searched the literature for studies evaluating the immune response to vaccines in RA patients receiving methotrexate (MTX) and/or biologic agents The efficacy of vaccination, assessed by the response rate based on increased antibody titers before and 3–6 weeks after vaccination, was extracted by one investigator and verified by another Results In total, 12 studies were included RA patients mainly received MTX, anti–tumor necrosis factor α (anti-TNFα), or rituximab (RTX) Influenza vaccination response was reduced for RTX (43 patients; pooled odds ratio [OR] 044 [95% confidence interval (95% CI) 017–112] for H1N1, OR 011 [95% CI 004–031] for H3N2, and OR 029 [95% CI 010–081] for B) but not for anti-TNFα (308 patients; OR 093 [95% CI 036–237] for H1N1, OR 079 [95% CI 034–183] for H3N2, and OR 079 [95% CI 037–170] for B) For MTX, results differed depending on the method of analysis (222 patients; OR 035 [95% CI 018–066] for at least 2 strains, ORs were close to 10 in the single strain analysis) Pneumococcal vaccination response was reduced for 139 patients receiving MTX compared with controls (OR 033 [95% CI 020–054] for serotype 6B and OR 058 [95% CI 036–094] for 23F) but not for anti-TNFα (258 patients; OR 096 [95% CI 057–159] for 6B and OR 120 [95% CI 057–254] for 23F) For RTX, the response was reduced (88 patients; OR 025 [95% CI 011–058] for 6B and OR 021 [95% CI 004–105] for 23F) Conclusion MTX decreases humoral response to pneumococcal vaccination and may impair response to influenza vaccination The immune response to both vaccines is reduced with RTX but not with anti-TNFα therapy in RA patients