Surface-induced layer formation in polyelectrolytes

We analyze, by means of an RPA calculation, the conditions under which a mixture of oppositely charged polyelectrolytes can micro-segregate in the neighborhood of a charged surface creating a layered structure. A number of stable layers can be formed if the surface is sufficiently strongly charged even at temperatures at which the bulk of the mixture is homogeneous.Comment: 6 pages, 3 figures, revtex, epsf, psfi

Competing Interactions among Supramolecular Structures on Surfaces

A simple model was constructed to describe the polar ordering of non-centrosymmetric supramolecular aggregates formed by self assembling triblock rodcoil polymers. The aggregates are modeled as dipoles in a lattice with an Ising-like penalty associated with reversing the orientation of nearest neighbor dipoles. The choice of the potentials is based on experimental results and structural features of the supramolecular objects. For films of finite thickness, we find a periodic structure along an arbitrary direction perpendicular to the substrate normal, where the repeat unit is composed of two equal width domains with dipole up and dipole down configuration. When a short range interaction between the surface and the dipoles is included the balance between the up and down dipole domains is broken. Our results suggest that due to surface effects, films of finite thickness have a none zero macroscopic polarization, and that the polarization per unit volume appears to be a function of film thickness.Comment: 3 pages, 3 eps figure

Synchronization of the Frenet-Serret linear system with a chaotic nonlinear system by feedback of states

A synchronization procedure of the generalized type in the sense of Rulkov et al [Phys. Rev. E 51, 980 (1995)] is used to impose a nonlinear Malasoma chaotic motion on the Frenet-Serret system of vectors in the differential geometry of space curves. This could have applications to the mesoscopic motion of biological filamentsComment: 12 pages, 7 figures, accepted at Int. J. Theor. Phy

Toward the Simulation of Flashing Cryogenic Liquids by a Fully Compressible Volume of Fluid Solver

We present a fully compressible single-fluid volume of fluid (VOF) solver with phase change for high-speed flows, where the atomization of the liquid can occur either by the aerodynamics or by the effect of the local pressure. The VOF approximation among a non-miscible phase (non-condensable gas) and a mixture of two fluids (liquid and vapor) represents the liquid core of the jet and its atomization. A barotropic model is used in combination with the equation of state (EoS) to link the mixture density to pressure and temperature. The solver is written with the aim to simulate high-pressure injection in gas–liquid systems, where the pressure of the liquid is great enough to cause significant compression of the surrounding gas. Being designed in an C++ object-oriented fashion, the solver is able to support any kind of EoS; the aim is to apply it to the simulation of the injection of liquid propellant in rocket engines. The present work includes the base development; a verification assessment of the code is provided by the solution of a set of numerical experiments to prove the boundedness, convergence and accuracy of the method. Experimental measurements of a cavitating microscopic in-nozzle flow, available in the literature, are finally used for a first validation with phase change

Junior Recital

List of performers and performances

Relationship between vaccination and nutritional status in children: Analysis of recent demographic and health surveys

BACKGROUND A body of evidence suggests that vaccines support the development of the immune system and also improve overall health. OBJECTIVE To study the effect of the complete basic vaccination schedule (Bacille Calmette-Guerin, i.e., BCG; measles; polio 3; and Diphtheria, Tetanus toxoids, and Pertussis, i.e., DTP3) on nutritional status of children under 2 years of age. METHODS Recent DHS data from 16 countries conducted after 2013 were used. After a bivariate descriptive analysis, a logistic regression analysis was conducted to predict the likelihood of underweight, stunting, and wasting by immunization status. A combined odds ratio was computed and adjusted for background variables. RESULTS A significantly higher prevalence of underweight was found among children with incomplete vaccination schedules in seven countries. Similarly, wasting and stunting were frequently observed in under-vaccinated children in four countries. Moreover, logistic regression adjusted for background variables revealed a relation between incomplete vaccination and underweight in Angola, Chad, and Guatemala (95% CI lower bound > 1). Combining data of all countries, underweight (adjusted Odds Ratio, aOR 1.21, 95% CI 1.11-1.31), wasting (aOR 1.18, 95% CI 1.05-1.33), and stunting (aOR 1.07, 95% CI 1.00-1.14) were associated with poor vaccination status. The overall effect was consistent with both sexes except the results for wasting for females and stunting for males, though insignificant. CONTRIBUTION To our knowledge, this is the first paper assessing the relation between vaccination and nutritional status at a multi-country level with a huge dataset. Our analysis suggests a poor nutritional status in children with an incomplete vaccination schedule

Control System for Less than Wind Turbines 1500W

Using wind power generation is another alternative for remote homes, where there is no electricity grid. Especially in Ecuador there are several places where the wind resource is really stable for the year, though at times the wind regime it becomes turbulent wind speeds become quite high exceeding 12 m / s affecting the wind turbine components.Generally in the Ecuadorian highlands are available permanent winds of medium intensity capable of generating electricity, but by having a system of turbulence for short periods of time it jeopardizes the deployed equipment and therefore the investments made by what this study guarantees the stability of small wind turbines that are very useful in our environment to generate electricity in field type housing shelters