Irreversible Thermodynamics in Multiscale Stochastic Dynamical Systems

This work extends the results of the recently developed theory of a rather complete thermodynamic formalism for discrete-state, continuous-time Markov processes with and without detailed balance. We aim at investigating the question that whether and how the thermodynamic structure is invariant in a multiscale stochastic system. That is, whether the relations between thermodynamic functions of state and process variables remain unchanged when the system is viewed at different time scales and resolutions. Our results show that the dynamics on a fast time scale contribute an entropic term to the "internal energy function", $u_S(x)$, for the slow dynamics. Based on the conditional free energy $u_S(x)$, one can then treat the slow dynamics as if the fast dynamics is nonexistent. Furthermore, we show that the free energy, which characterizes the spontaneous organization in a system without detailed balance, is invariant with or without the fast dynamics: The fast dynamics is assumed to reach stationarity instantaneously on the slow time scale; they have no effect on the system's free energy. The same can not be said for the entropy and the internal energy, both of which contain the same contribution from the fast dynamics. We also investigate the consequences of time-scale separation in connection to the concepts of quasi-stationaryty and steady-adiabaticity introduced in the phenomenological steady-state thermodynamics

Oscillation arrest in the mouse somitogenesis clock presumably takes place via an infinite period bifurcation

This is the author accepted manuscript available from arXiv.org via the DOI in this record.In this work we address the question of how oscillations are arrested in the mouse somitogenesis clock when the determination front reaches presomitic cells. Based upon available experimental evidence we hypothesize that the mechanism underlying such a phenomenon involves the interaction between a limit cycle (originated by a delayed negative feedback loop) and a bistable switch (originated by a positive feedback loop). With this hypothesis in mind we construct the simplest possible model comprising both negative and positive feedback loops and show that (with a suitable choice of paremeters): 1) it can show an oscillatory behavior, 2) oscillations are arrested via an infinite-period bifurcation whenever the different gene-expression regulatorinputs act together in an additive rather than in a multiplicative fashion, and 3) this mechanism for oscillation arrest is compatible whit plentiful experimental observations

Planta de alimentos UNLP: herramientas de gestión universitaria para su implementación

La Universidad Nacional de La Plata es una de las instituciones de Educación Superior más reconocidas en América Latina, y esto, junto a su permanente compromiso social, la posiciona como un actor fundamental para la definición, articulación e implementación de políticas públicas en los ámbitos local, regional y nacional. En este marco surge el programa de Asistencia al Desarrollo Productivo Local, que busca intervenir en la agenda regional, aportando conocimiento y propuestas técnicas que puedan llevar a soluciones eficaces para los problemas del sector productivo. Se propone articular esfuerzos con emprendimientos, empresas recuperadas, PYMES y cooperativas, para generar y fortalecer la planificación de las cadenas productivas con especial detenimiento en los sectores de mayor emergencia económica. En el período de gestión 2018-2022 la concreción del proyecto de creación de una Planta Elaboradora de Alimentos Desecados en la UNLP se ha constituido en uno de los ejes centrales del Programa, contextualizado al momento histórico que atraviesa la región y articulado con líneas de trabajo previas, como el seguimiento de la situación del sector productivo de alimentos del Gran La Plata y la preocupante crisis alimentaria que los sectores más postergados de la región atraviesan. El presente Trabajo Final Integrador propone, a partir del análisis del contexto y de las dinámicas institucionales, un Plan para el desarrollo del Proyecto, que contempla los procesos e instrumentos de Implementación, Funcionamiento y Evaluación del mismo.Instituto de Investigaciones en Educación Superio

A Comparative Study of Electric Load Curve Changes in an Urban Low-Voltage Substation in Spain during the Economic Crisis (2008-2013)

This paper presents a comparative study of the electricity consumption (EC) in an urban low-voltage substation before and during the economic crisis (2008-2013). This low-voltage substation supplies electric power to near 400 users. The EC was measured for an 11-year period (2002-2012) with a sampling time of 1 minute. The study described in the paper consists of detecting the changes produced in the load curves of this substation along the time due to changes in the behaviour of consumers. The EC was compared using representative curves per time period (precrisis and crisis). These representative curves were obtained after a computational process, which was based on a search for days with similar curves to the curve of a determined (base) date. This similitude was assessed by the proximity on the calendar, day of the week, daylight time, and outdoor temperature. The last selection parameter was the error between the nearest neighbour curves and the base date curve. The obtained representative curves were linearized to determine changes in their structure (maximum and minimum consumption values, duration of the daily time slot, etc.). The results primarily indicate an increase in the EC in the night slot during the summer months in the crisis perio

Molecular thermodynamics of adsorption using discrete-potential systems

A molecular thermodynamics approach has been developed in order to describe the adsorption of fluids onto solid surfaces based on the use of discrete-potential fluid models. Using perturbation theories for fluids such as the Statistical Associating Fluid Theory (SAFT) and the Discrete Potential Theory (DPT), in combination with molecular simulation, we have formulated a two-dimensional approach to describe systems of interest for the oil industry, such as adsorption isotherms of carbon dioxide and asphaltenes

Flagellar Motility of Trypanosoma cruzi Epimastigotes

The hemoflagellate Trypanosoma cruzi is the causative agent of American trypanosomiasis. Despite the importance of motility in the parasite life cycle, little is known about T. cruzi motility, and there is no quantitative description of its flagellar beating. Using video microscopy and quantitative vectorial analysis of epimastigote trajectories, we find a forward parasite motility defined by tip-to-base symmetrical flagellar beats. This motion is occasionally interrupted by base-to-tip highly asymmetric beats, which represent the ciliary beat of trypanosomatid flagella. The switch between flagellar and ciliary beating facilitates the parasite's reorientation, which produces a large variability of movement and trajectories that results in different distance ranges traveled by the cells. An analysis of the distance, speed, and rotational angle indicates that epimastigote movement is not completely random, and the phenomenon is highly dependent on the parasite behavior and is characterized by directed and tumbling parasite motion as well as their combination, resulting in the alternation of rectilinear and intricate motility paths

Functional vision barriers: a new concept analyzed in terms of human visual performance

In this work we introduce a new category of barriers that we call "functional vision barriers." This expression refers to lighting and visual elements that may complicate or hinder functional vision and may make life even more difficult for people with visual defects. These barriers appear as a consequence of certain negative effects caused by the poor design of the visual stimulus or visual environment that surrounds it in which lighting is one of the main factors. We use the term "functional vision" because this expression refers to the ability of the visual system to perform everyday tasks. We analyzed some of our previous results with regard to situations that can be considered "functional vision barriers": (1) stimuli with low luminance contrast information in which the addition of chromatic contrast improves visual performance and (2) tasks that are performed in the presence of a glare source in the visual field, diminishing visual performance and reducing brightness perception.Fil: Colombo, Elisa Margarita. Universidad Nacional de Tucuman. Facultad de Cs.exactas y Tecnologia. Departamento de Luminotecnia, Luz y Vision; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucuman. Instituto de Investigacion En Luz, Ambiente y Vision; ArgentinaFil: O´Donell, Beatriz M.. Universidad Nacional de Tucuman. Facultad de Cs.exactas y Tecnologia. Departamento de Luminotecnia, Luz y Vision; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucuman. Instituto de Investigacion En Luz, Ambiente y Vision; ArgentinaFil: Santillán, Javier Enrique. Universidad Nacional de Tucuman. Facultad de Cs.exactas y Tecnologia. Departamento de Luminotecnia, Luz y Vision; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucuman. Instituto de Investigacion En Luz, Ambiente y Vision; ArgentinaFil: Issolio, Luis Alberto. Universidad Nacional de Tucuman. Facultad de Cs.exactas y Tecnologia. Departamento de Luminotecnia, Luz y Vision; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucuman. Instituto de Investigacion En Luz, Ambiente y Vision; Argentin

Boolean Models of Bistable Biological Systems

This paper presents an algorithm for approximating certain types of dynamical systems given by a system of ordinary delay differential equations by a Boolean network model. Often Boolean models are much simpler to understand than complex differential equations models. The motivation for this work comes from mathematical systems biology. While Boolean mechanisms do not provide information about exact concentration rates or time scales, they are often sufficient to capture steady states and other key dynamics. Due to their intuitive nature, such models are very appealing to researchers in the life sciences. This paper is focused on dynamical systems that exhibit bistability and are desc ribedby delay equations. It is shown that if a certain motif including a feedback loop is present in the wiring diagram of the system, the Boolean model captures the bistability of molecular switches. The method is appl ied to two examples from biology, the lac operon and the phage lambda lysis/lysogeny switch

Evaluation of conductive concrete made with steel slag aggregates

The incorporation of black steel slag (waste from steel production) in concrete responds to a greater awareness of sustainability. In addition, it is capable of increasing electrical conductivity. The objective of this work is to achieve multifunctional concretes with higher mechanical performance and which can modify the electrical characteristics. In this work, natural aggregates have been replaced by different aggregates of steel slags from Spanish industries and the mechanical characteristics of compression, modulus of elasticity, indirect traction and electrical characteristics of these concretes have been studied with respect to reference mixtures. Encouraging results have been obtained for concrete with slag and metallic fibers, improving the electrical conductive capacity by almost 70% and improving the mechanical performance by 14%.The authors acknowledge the financial support provided by the project PID2019-106555RB-I00. The first author acknowledges the financial support from Agència de Gestió d'Ajuts Universitaris i de Recerca (AGAUR), with the doctoral fellowship: Personal investigador novell (FI) 2021. We would also like to thank the following companies: Promsa, Sidenor, Calcinor, Hormor and Adec for supplying the slag, without which this study would not be possible.Peer ReviewedPostprint (published version