Evaporation of a thin film: diffusion of the vapour and Marangoni instabilities

The stability of an evaporating thin liquid film on a solid substrate is investigated within lubrication theory. The heat flux due to evaporation induces thermal gradients; the generated Marangoni stresses are accounted for. Assuming the gas phase at rest, the dynamics of the vapour reduces to diffusion. The boundary condition at the interface couples transfer from the liquid to its vapour and diffusion flux. A non-local lubrication equation is obtained; this non-local nature comes from the Laplace equation associated with quasi-static diffusion. The linear stability of a flat film is studied in this general framework. The subsequent analysis is restricted to moderately thick films for which it is shown that evaporation is diffusion limited and that the gas phase is saturated in vapour in the vicinity of the interface. The stability depends only on two control parameters, the capillary and Marangoni numbers. The Marangoni effect is destabilising whereas capillarity and evaporation are stabilising processes. The results of the linear stability analysis are compared with the experiments of Poulard et al (2003) performed in a different geometry. In order to study the resulting patterns, the amplitude equation is obtained through a systematic multiple-scale expansion. The evaporation rate is needed and is computed perturbatively by solving the Laplace problem for the diffusion of vapour. The bifurcation from the flat state is found to be a supercritical transition. Moreover, it appears that the non-local nature of the diffusion problem unusually affects the amplitude equation

Bayesian inference on compact binary inspiral gravitational radiation signals in interferometric data

Presented is a description of a Markov chain Monte Carlo (MCMC) parameter estimation routine for use with interferometric gravitational radiational data in searches for binary neutron star inspiral signals. Five parameters associated with the inspiral can be estimated, and summary statistics are produced. Advanced MCMC methods were implemented, including importance resampling and prior distributions based on detection probability, in order to increase the efficiency of the code. An example is presented from an application using realistic, albeit fictitious, data.Comment: submitted to Classical and Quantum Gravity. 14 pages, 5 figure

Numerical analysis on the effect of normotensive and hypertensive physiological conditions onto hemodynamic characteristics in stented carotid artery

An arterial re-blockage or restenosis by abnormal atherosclerosis and thrombosis progression in carotid artery is associated with the geometry of the implanted medical device, called as stent. However, the physiological conditions consisting of normotensive and hypertensive blood flow in the stented carotid artery are rarely studied in term of hemodynamic characteristic especially near the geometry of the stent strut. Thus, the objective of this study is to determine the hemodynamic effect based on its characteristics at different stent strut configurations in carotid artery as well as analyzing the critical parameters at varying blood physiological conditions. Six different geometries of stent that resembles the existing medical device have been studied at three varying physiological conditions of blood. The study was conducted through computational fluid dynamic (CFD) method to analyze the hemodynamic characteristics of the blood flow parameters. In overall physiological condition, the stent geometry of Type VI which are resembling to Acculink (Abbott Vascular), had been shown to have the best hemodynamic characteristic by the parameters of time averaged wall shear stress low (TAWSSlow), oscillatory shear index (OSI) and relative residence time (RRT), which contributed with average luminal surface area percentage about 10.443%, 99.849% and 98.736%, respectively. As the physiological condition of blood flow increased from normotensive to hypertensive, there were two parameters shown to have critical hemodynamic characteristics at different stent geometries which are TAWSSlow and time averaged wall shear stress gradient (TAWSSG) that achieved about 32.388% and 36.629%, respectively. The study had shown that the different stent strut geometries had presented different hemodynamic characteristics due to the effect by the blood flow physiological condition

Higher Spin de Sitter Holography from Functional Determinants

We discuss further aspects of the higher spin dS/CFT correspondence. Using a recent result of Dunne and Kirsten, it is shown how to numerically compute the partition function of the free Sp(N) model for a large class of SO(3) preserving deformations of the flat/round metric on R^3/S^3 and the source of the spin-zero single-trace operator dual to the bulk scalar. We interpret this partition function as a Hartle-Hawking wavefunctional. It has a local maximum about the pure de Sitter vacuum. Restricting to SO(3) preserving deformations, other local maxima (which exceed the one near the de Sitter vacuum) can peak at inhomogeneous and anisotropic values of the late time metric and scalar profile. Numerical experiments suggest the remarkable observation that, upon fixing a certain average of the bulk scalar profile at I^+, the wavefunction becomes normalizable in all the other (infinite) directions of the deformation. We elucidate the meaning of double trace deformations in the context of dS/CFT as a change of basis and as a convolution. Finally, we discuss possible extensions of higher spin de Sitter holography by coupling the free theory to a Chern-Simons term.Comment: 30 pages plus appendices; v2 references adde

Identification of Characteristic Frequency in Proteins using Power Spectral Density

technique for detection of characteristic frequency in proteins using power spectral density is described. The vast majority of proteins binds to other proteins at some time in their existence in order to perform various functions. Characteristic frequency is of utmost importance since it forms the basis for protein-target interaction, both protein and target must share common characteristic frequency for successful binding, thus an approach for identification of characteristic frequency using power spectral density (PSD) has been illustrated in this paper