Persistent global power fluctuations near a dynamic transition in electroconvection

This is a study of the global fluctuations in power dissipation and light transmission through a liquid crystal just above the onset of electroconvection. The source of the fluctuations is found to be the creation and annihilation of defects. They are spatially uncorrelated and yet temporally correlated. The temporal correlation is seen to persist for extremely long times. There seems to be an especially close relation between defect creation/annihilat ion in electroconvection and thermal plumes in Rayleigh-B\'enard convection

The Conformation of Interfacially Adsorbed Ranaspumin-2 Is an Arrested State on the Unfolding Pathway

Ranaspumin-2 (Rsn-2) is a surfactant protein found in the foam nests of the t\'{u}ngara frog. Previous experimental work has led to a proposed model of adsorption which involves an unusual clam shell-like `unhinging' of the protein at an interface. Interestingly, there is no concomitant denaturation of the secondary structural elements of Rsn-2 with the large scale transformation of its tertiary structure. In this work we use both experiment and simulation to better understand the driving forces underpinning this unusual process. We develop a modified G\={o}-model approach where we have included explicit representation of the side-chains in order to realistically model the interaction between the secondary structure elements of the protein and the interface. Doing so allows for the study of the underlying energy landscape which governs the mechanism of Rsn-2 interfacial adsorption. Experimentally, we study targeted mutants of Rsn-2, using the Langmuir trough, pendant drop tensiometry and circular dichroism, to demonstrate that the clam-shell model is correct. We find that Rsn-2 adsorption is in fact a two-step process: the hydrophobic N-terminal tail recruits the protein to the interface after which Rsn-2 undergoes an unfolding transition which maintains its secondary structure. Intriguingly, our simulations show that the conformation Rsn-2 adopts at an interface is an arrested state along the denaturation pathway. More generally, our computational model should prove a useful, and computationally efficient, tool in studying the dynamics and energetics of protein-interface interactions.Comment: 8 figure

PLoS One

BACKGROUND: The association between liver stiffness measurements (LSM) and mortality has not been fully described. In particular the effect of LSM on all-cause mortality taking sustained virological response (SVR) into account needs further study. METHODS: HIV/HCV participants in the French nation-wide, prospective, multicenter ANRS CO13 HEPAVIH cohort, with >/=1 LSM by FibroScan (FS) and a detectable HCV RNA when the first valid FS was performed were included. Cox proportional hazards models with delayed entry were performed to determine factors associated with all-cause mortality. LSM and SVR were considered as time dependent covariates. RESULTS: 1,062 patients were included from 2005 to 2015 (69.8% men, median age 45.7 years (IQR 42.4-49.1)). 21.7% had baseline LSM >12.5 kPa. Median follow-up was 4.9 years (IQR 3.2-6.1). 727 (68.5%) were ever treated for HCV: 189 of them (26.0%) achieved SVR. 76 deaths were observed (26 liver-related, 10 HIV-related, 29 non-liver-non-HIV-related, 11 of unknown cause). At the age of 50, the mortality rate was 4.5% for patients with LSM 12.5 kPa. LSM >12.5 kPa (adjusted Hazard Ratio [aHR] = 3.35 [2.06; 5.45], p12.5 kPa was strongly associated with all-cause mortality independently of SVR and other important covariates. Our results suggest that close follow-up of these patients should remain a priority even after achieving SVR

On the measurement of the surface pressure in Langmuir films with finite shear elasticity

We investigate the use of the Wilhelmy plate method to measure the surface pressure in a solid-like Langmuir film under compression. Layers of the protein hydrophobin, which exhibits a high shear elastic modulus, are spread and compressed in a Langmuir trough. The resulting isotherms are classified according to the surface pressure and distance between the barriers measured at the onset of buckling. We find that the surface pressure measured in the centre of the layer at the onset of buckling decays with increasing distance between the barriers (which can be tuned by varying the amount of material spread initially). However, unlike the case of particle rafts, the length scale of this decay is not controlled by the width of the trough but rather by the size of the Wilhelmy plate used. We use experiments and a computational model to suggest that this independence of trough width may be attributed to the localised nature of the effect of the trough walls. Our work highlights the potential pitfalls of using the Wilhelmy method to characterize layers with high shear rigidity and may lead to a better understanding of the use of the Wilhlemy plate to measure the surface stress tensor. © 2011 The Royal Society of Chemistry

LES PRÉFÉRENCES ALIMENTAIRES DU PORCELET. VII. - APPÉTIBILITÉ DES TOURTEAUX

International audienc

INFLUENCE DE L'ALIMENTATION COMPLÉMENTAIRE SUR LA CROISSANCE DU PORCELET AVANT LE SEVRAGE

International audienc

VALEUR ALIMENTAIRE DU MAÏS ENSILÉ A DIFFÉRENTS STADES DE MATURITÉ POUR LA TRUIE, LE PORCELET ET LE PORC EN CROISSANCE-FINITION

International audienc