National University of La Plata

About: National University of La Plata is a education organization based out in La Plata, Argentina. It is known for research contribution in the topics: Population & Large Hadron Collider. The organization has 12993 authors who have published 30013 publications receiving 495118 citations. The organization is also known as: UNLP & Universidad Nacional de La Plata.

Gender, violence and HIV: women's survival in the streets.

Abstract: In this article I propose that genderinequality promotes – directly or indirectly –vulnerability to HIV as a consequence of amultidimensional violence (structural, symbolicand physical) experienced by injection drugusing (IDU) women in The Mission District (SanFrancisco). Given the female subordinated positionstipulated by the street ideology, I analyzehow drug dependence afforded by precariousstrategies of subsistence places IDU womenunder multiple dangers and threats. In thissetting, unequal gender relations are part of acomplex system of transactions in the streeteconomy and a way to reduce or increase theeveryday violence. Facing multiple dangers andrisks, some women adopt a subordinatedposition, some try to negotiate the conditionsof the exchanges and the others resist theexploitation. Finally, everyday violence under conditions ofgender inequality and scarcity of resourcesimposes a logic defined by the challenge ofsurvival under the threat of immediate dangers,which transform HIV into a secondary risk.

Size effect and boundary conditions in the brazilian test: theoretical analysis

Abstract: Splitting strength determined in the Brazilian test is assumed to be a property independent of size and uniquely related to the intrinsic material strength. However, as was experimentally demonstrated by various authors, the splitting strength depends on the specimen size. In this paper, the size effect in the Brazilian test is analyzed theoretically using a nonlinear fracture model based on cohesive crack concepts and the results obtained are compared with the classical strength limit approach. Two important variables are studied: the load-bearing strip and the geometry of the specimen. From the numerical results a closed form expression is proposed, dependent on the width of the bearing strip and on geometry. The results confirm that splitting strength decreases with the specimen size, tending towards an asymptotic solution for large size specimens. Within the size range analyzed (0.1 m to 2.5 m diameter for typical concrete) the splitting strength can vary by up to 25% in cylindrical specimens and by up to 35% in prismatic square section specimens, although this size effect is strongly dependent on the load-bearing strip. For widths of bearing strip smaller than 4% of the specimen diameter, the effect of the specimen size is negligible and the splitting strength approaches the tensile strength for any practical specimen size.

Hydrogen reactivity of palladium nanoparticles coated with mixed monolayers of alkyl thiols and alkyl amines for sensing and catalysis applications.

Abstract: Palladium monolayer-protected clusters (MPCs) coated with octylamines (C8NH2), hexanethiolates (C6S), and mixed monolayers of C8NH2 and C6S exhibit significantly different reactivities with hydrogen gas, depending on the relative amounts of the two ligands coating the Pd nanoparticle surface, as determined by UV−vis spectroscopy of Pd MPCs in solution and electronic measurements of films of Pd MPCs as a function of exposure time to hydrogen. The average estimated composition of the ∼3.0 nm diameter Pd MPCs was Pd919(C6S)192 or Pd919(C8NH2)177−x(C6S)x, where x was varied to be 0, 3, 10, 16, 32, or 81 by the synthesis of pure C8NH2 Pd MPCs and subsequent liquid-phase place exchange with a varied amount of C6SH. When x = 0−10, the Pd MPCs react strongly with H2, leading to aggregated particles in solution and large irreversible changes in the morphology of films accompanied by an increase in film conductivity by 2−5 orders of magnitude. Pd919(C6S)192 MPCs are stable against significant aggregation in solutio...

The role of CaMKII regulation of phospholamban activity in heart disease.

Abstract: Phospholamban (PLN) is a phosphoprotein in cardiac sarcoplasmic reticulum (SR) that is a reversible regulator of the Ca2+-ATPase (SERCA2a) activity and cardiac contractility. Dephosphorylated PLN inhibits SERCA2a and PLN phosphorylation, at either Ser16 by PKA or Thr17 by Ca2+-calmodulin-dependent protein kinase (CaMKII), reverses this inhibition. Through this mechanism, PLN is a key modulator of SR Ca2+ uptake, Ca2+ load, contractility and relaxation. PLN phosphorylation is also the main determinant of β1-adrenergic responses in the heart. Although phosphorylation of Thr17 by CaMKII contributes to this effect, its role is subordinate to the PKA-dependent increase in cytosolic Ca2+, necessary to activate CaMKII. Furthermore, the effects of PLN and its phosphorylation on cardiac function are subject to additional regulation by its interacting partners, the anti-apoptotic HAX-1 protein and Gm or the anchoring unit of protein phosphatase 1. Regulation of PLN activity by this multimeric complex becomes even more important in pathological conditions, characterized by aberrant Ca2+-cycling. In this scenario, CaMKII-dependent PLN phosphorylation has been associated with protective effects in both acidosis and ischemia/reperfusion. However, the beneficial effects of increasing SR Ca2+ uptake through PLN phosphorylation may be lost or even become deleterious, when these occur in association with alterations in SR Ca2+ leak. Moreover, a major characteristic in human and experimental heart failure is depressed SR Ca2+ uptake, associated with decreased SERCA2a levels and dephosphorylation of PLN, leading to decreased SR Ca2+ load and impaired contractility. Thus, the strategy of altering SERCA2a and/or PLN levels or activity to restore perturbed SR Ca2+ uptake is a potential therapeutic tool for heart failure treatment. We will review here the role of CaMKII-dependent phosphorylation of PLN at Thr17 on cardiac function under physiological and pathological conditions.