Transport networks’ accessibility and jobs’ accessibility: the significance of this correlation on the configuration of labor market and their consequences on social configuration in the city Bogotá

Several researches have been done about transport in Bogotá (Colombia) but no one has treated the impact of the transport network on the configuration of employment in the city. This research has two different aims which are directly interrelated. The definition of the effective size of labor market in the city is necessary to sheds light on the relation of transport accessibility and type of jobs or social classes within different zones in Bogotá. We support the first part of our study on the existing literature about the effective size of labor market. Under the specification of a conceptual model, we want to demonstrate the significant correlation (even causality) between accessibility and type of jobs in Bogotá. In order to capture the possible endogeneity among transport' accessibility and type of jobs we will use a Structural Equation Modeling (SEM). Results will give us enough tools to know if transport network' accessibility, jobs' accessibility and type of jobs (or social classes) are large interrelated or not in the city of Bogotá. It will also let us to know if improvement of public network infrastructures traduced in a tacit enhancement on accessibility has a positive effect on incomes of inhabitants. We will understand the degree of correlation between accessibility to public transports and accessibility to jobs with respect to type of jobs and/or social class of labor force. Actually, first results show us that, there is a direct relationship between socio-economic class and time accessibility to jobs; the more accessibility of public transport system is in a zone of the city, the best is the social class and the better are the type of jobs of inhabitants so the highest will be the income. Nevertheless, it is observed (but not proved yet) that in some zones of the city where accessibility index is high, social class and types of jobs of inhabitants connected and living in these zones are not the best ones. Even so, we hope that with our methodology and data we could collect, we will be able to elucidate our research question.

Towards a Unified Framework for Declarative Structured Communications

We present a unified framework for the declarative analysis of structured communications. By relying on a (timed) concurrent constraint programming language, we show that in addition to the usual operational techniques from process calculi, the analysis of structured communications can elegantly exploit logic-based reasoning techniques. We introduce a declarative interpretation of the language for structured communications proposed by Honda, Vasconcelos, and Kubo. Distinguishing features of our approach are: the possibility of including partial information (constraints) in the session model; the use of explicit time for reasoning about session duration and expiration; a tight correspondence with logic, which formally relates session execution and linear-time temporal logic formulas

The influence of surface roughness on the adhesive interactions and phase behavior of suspensions of calcite nanoparticles

We investigate the impact of nanoparticle roughness on the phase behaviour of suspensions in models of calcium carbonate nanoparticles. We use a Derjaguin approach that incorporates roughness effects and interactions between the nanoparticles modelled with a combination of DLVO forces and hydration forces, derived using experimental data and atomistic molecular dynamics simulations, respectively. Roughness effects, such as atomic steps or terraces appearing in mineral surfaces result in very different effective inter-nanoparticle potentials. Using stochastic Langevin Dynamics computer simulations and the effective interparticle interactions we demonstrate that relatively small changes in the roughness of the particles modify significantly the stability of the suspensions. We propose that the sensitivity of the phase behavior to the roughness is connected to the short length scale of the adhesive attraction arising from the ordering of water layers confined between calcite surfaces. Particles with smooth surfaces feature strong adhesive forces, and form gel fractal structures, while small surface roughness, of the order of atomic steps in mineral faces, stabilize the suspension. We believe that our work helps to rationalize the contrasting experimental results that have been obtained recently using nanoparticles or extended surfaces, which provide support for the existence of adhesive or repulsive interactions, respectively. We further use our model to analyze the synergistic effects of roughness, pH and ion concentration on the phase behavior of suspensions, connecting with recent experiments using calcium carbonate nanoparticles