Mixing in thermally stratified nonlinear spin-up with sources and sinks

Stratified spin-up experiments in enclosed cylinders have reported the presence of small pockets of well-mixed fluids but quantitative measurements of the mixedness of the fluid has been lacking. Previous numerical simulations have not addressed these measurements. Here we present numerical simulations that address how the combined effect of spin-up and thermal boundary conditions enhances or hinders mixing of a fluid in a cylinder. Measurements of efficiency of mixing are based on the variance of temperature and explained in terms of the potential energy available. The numerical simulations of the Navier--Stokes equations for the problem with different sets of thermal boundary conditions at the horizontal walls helped shed some light on the physical mechanisms of mixing, for which a clear explanation was lacking.Comment: Submitted to Physics of Fluids, 9 figure

Size Distributions for All Cities: Lognormal and q-exponential functions

This paper analyses in detail the features offered by a function which is practically new to Urban Economics, the q-exponential, in describing city size distributions. We highlight two contributions. First, we propose a new and simple procedure for estimating their parameters. Second, and more importantly, we explain the characteristics associated with two traditional graphic methods (Zipf plots and cumulative density functions) for discriminating between functions. We apply them to the lognormal and q-exponential, justifying them as the best functions for explaining the entire distribution, and that the relationship between them is of complementarity. The empirical evidence relies on the analysis of urban data of three countries (USA, Spain and Italy) over all of the 20th century.

Cosolute partitioning in polymer networks: Effects of flexibility and volume transitions

We study the partitioning of cosolute particles in a thin film of a semi-flexible polymer network by a combination of coarse-grained (implicit-solvent) stochastic dynamics simulations and mean-field theory. We focus on a wide range of solvent qualities and cosolute-network interactions for selected polymer flexibilities. Our investigated ensemble (isothermal-isobaric) allows the network to undergo a volume transition from extended to collapsed state while the cosolutes can distribute in bulk and network, correspondingly. We find a rich topology of equilibrium states of the network and transitions between them, qualitatively depending on solvent quality, polymer flexibility, and cosolute-network interactions. In particular, we find a novel `cosolute-induced' collapsed state, where strongly attractive cosolutes bridge network monomers albeit the latter interact mutually repulsive. Finally, the cosolutes' global partitioning `landscape', computed as a function of solvent quality and cosolute-network interactions, exhibits very different topologies depending on polymer flexibility. The simulation results are supported by theoretical predictions obtained with a two-component mean-field approximation for the Helmholtz free energy that considers the chain elasticity and the particle interactions in terms of a virial expansion. Our findings have implications on the interpretation of transport processes and permeability in hydrogel films, as realized in filtration or macromolecular carrier systems.Comment: Macromolecules (2017

Factores que influyen en el impacto subjetivo de la estética oral y la necesidad de tratamiento ortodóntico auto percibida en adolescentes

El actual estudio es prospectivo, prolectivo, transversal, descriptivo y observacional-analítico tuvo como principal objetivo determinar si la edad, el género y la Institución Educativa, influyen en los índices de la escala subjetiva del impacto de estética oral OASIS y el índice de necesidad de tratamiento ortodóncico IOTN en los adolescentes de la ciudad de Cajamarca en el año 2021. Para la aplicación de los índices OASIS y IOTN de manera virtual, se realizó una prueba piloto a la cual se le aplicó el estadístico Alfa de Cronbach, obteniendo una confiabilidad muy significativa con valor de alfa igual a 0.827 El instrumento se aplicó a 357 escolares de secundaria de 02 Instituciones Educativas, una Estatal y otra Particular. La población se seleccionó a través de un procedimiento no probabilístico por conveniencia. Se presentan frecuencias absolutas y porcentuales. Para determinar si la edad, el sexo y la Institución Educativa, influyen en los índices de La Escala Subjetiva del Impacto de Estética Oral (OASIS) y El Índice de Necesidad de Tratamiento Ortodóncico (IOTN) en los adolescentes de la ciudad de Cajamarca, se emplearon modelos de Regresión Logística Multinomial. Se considera un nivel de significancia del 5%. El resultado mostró que la edad, el género y la Institución Educativa no influyeron en el índice de necesidad de tratamiento ortodóncico IOTN, mientras que el género si influyó, sólo en la categoría muy preocupado, en la escala subjetiva del impacto de estética oral OASIS, en los adolescentes de la ciudad de Cajamarca en el año 2021.The current study is prospective, prolective, cross-sectional, descriptive and observational-analytical. Its main objective was to determine if age, gender and the Educational Institution influence the indexes of the subjective scale of the impact of oral aesthetics OASIS and the index of need for IOTN orthodontic treatment in adolescents in the city of Cajamarca in 2021. For the application of the OASIS and IOTN indices virtually, a pilot test was carried out to which the Cronbach's Alpha statistical year was applied, obtaining a very high reliability. significant with alpha value equal to 0.827 The school instrument was applied to 357 high school students from 02 Educational Institutions, one State and one Private. The population was selected through a non-probabilistic procedure for convenience. Absolute and percentage frequencies are presented. To determine whether age, sex and educational institution influence the indexes of the Oral Aesthetics Impact Subjective Scale (OASIS) and the Orthodontic Treatment Needs Index (IOTN) in adolescents in the city of Cajamarca, it was used Multinomial Logistic Regression models. A significance level of 5% is considered. The result showed that age, gender and educational institution did not influence the index of need for orthodontic treatment IOTN, while gender did influence, only in the very concerned category, in the subjective scale of the impact of oral aesthetics OASIS, in adolescents in the city of Cajamarca in the year 2021.Tesi

Urban growth in the long term: Belgium, 1880–1970

We take advantage of a new data set on Belgian cities to test random growth, that is, Gibrat’s law. This unique data set provides annual population estimates for all Belgian municipalities (2680 cities) from 1880 to 1970. The use of panel data methodology and unit root tests can provide a precise test of Gibrat’s law (a unit root is equivalent to random growth). We run both time series and panel data unit root tests, thus obtaining strong support for random growth in the long term. Results hold when allowing for the presence of one and two structural breaks in the mean, with the timing of the breaks coinciding with some major historical events, such as the World Wars and the economic crisis of 1929–1933

Mecanismos moleculares de las proteínas de choque térmico (HSPs) implicados en el desarrollo neoplásico.

Las proteínas de choque térmico (HSPs) son inducidas por estrés celular y se expresan en niveles elevados en una amplia gama de tumores entre los que se incluyen el cáncer de seno, pulmón, próstata, colon, leucemias y estomago; esta sobre expresión está estrechamente asociada con resistencia a las terapias establecidas instituyendo un mal pronóstico. Las proteínas de choque térmico (HSPs) están involucradas en todas las fases del cáncer, desde la proliferación, la anti apoptosis, hasta en la invasión y metástasis, dentro de los mecanismos descritos por los cuales las HSPs incrementan la agresividad tumoral son la evasión de los estímulos apoptóticos y la respuesta inmune, pérdida de función de p53, expresión de proto oncogenes HER2 y c-Myc, activación de plasmina y MMP2 entre otros, todos cruciales para la tumorogénesis. De esta forma las HSPs se han convertido en objetivos para el diseño dirigido de fármacos anti-cáncer y estrategias de inmunoterapia

Exhaustion of Vascular Accesses for Haemodialysis: Access by Thrombosed Vein

I will describe, especially to professionals involved in vascular access, how recently occluded veins can be recanalized to implant a haemodialysis catheter. We recommend that it be a permanent one