Modelling of biological systems using multidimensional population balances

Biological systems are intrinsically heterogeneous and, consequently, their mathematical descriptions should account for this heterogeneity as it often influences the dynamic behaviour of the individual cells. For example, in the cell cycle dependent production ofproteins, it is necessary to account for the distribution of the individual cells with respect to their position in the cell cycle as this has a strong influence on protein production. A second notable example is the formation of cancerous cells. In this case, the failure of regulatory mechanisms results in the transition of somatic cells to their cancerous state. Therefore, in developing the corresponding mathematical model, it is necessary to consider both the different states of the cells as well as their regulation. In this regard, the population balance equation is the ideal mathematical framework to capture cell population heterogeneity as it elegantly takes into account the distribution of cell populations with respect to their intracellular state together with the phenomena of cell birth, division, differentiation and recombination. Recent developments in solution algorithms together with the exponential increase in computational abilities now permit the efficient solution of one-dimensional population balance models which attribute the heterogeneity of cell populations to differences in the age or mass of individual cells. The inherent complexity of biological systems implies that the differentiation of cells based on a single characteristic alone may not be sufficient to capture the underlying biological phenomena. Therefore, current research is focussing on the development of multi-dimensional population balances that consider the differentiation of cells based on multiple characteristics, most notably, the state of cells with respect to key intracellular metabolites. However, conventional numerical techniques are inefficient for the solution of the formulated population balance models and this warrants the development of novel, tailor-made algorithms. This thesis presents one such solution algorithm and demonstrates its application to the study of several biological systems. The algorithm developed herein employs a finite-volume technique to convert the partial-differential equation comprising the population balance model into a set of ordinary differential equations. A two-tier technique based on the solution technique for inhomogeneous differential equations is then developed to solve the system of ordinary differential equations. This approach has two main advantages: (a) the decomposition technique considerably reduces the stiffness of the system of equations enabling more efficient solution, and (b) semianalytical solutions for the integrals employed in the modelling of cell division and differentiation can be obtained further reducing computation times. Further improvements in solution efficiency are obtained by the formulation of a two-level discretisation algorithm. In this approach, processes such as cell growth which are more sensitive to the discretisation are solved using a fine grid whereas less sensitive processes such as cell' division - which are usually more computationally expensive - are solved using a coarse grid at a higher level. Thus, further improvements are obtained in the efficiency of the technique. The solution algorithm is applied to various multi-dimensional population balance models of biological systems. The technique is first demonstrated on models of oscillatory dynamics in yeast glycolysis, cell-cycle related oscillations in eukaryotes, and circadian oscillations in crayfish. A model of cell division and proliferation control in eukaryotes is an example of a second class of problems where extracellular phenomena influence the behaviour of cells. As a third case for demonstration, a hybrid model of biopolymer accumulation in bacteria is formulated. In this case, cybernetic modelling principles are used to account for intracellular competitions while the population balance framework takes into consideration the heterogeneity of the cell population. Another important aspect in the formulation ofmulti-dimensional population balances is the development of the intracellular models themselves. While research in the biological sciences is permitting the formulation of detailed dynamic models of various bioprocesses, the accurate estimation of the kinetic parameters in these models can be difficult due to the unavailability of sufficient experimental data. This can result in considerable parametric uncertainty as is demonstrated on a simple cybernetic' model of biopolymer accumulation in bacteria. However, it is shown that, via the use of systems engineering tools, experiments can be designed that permit the accurate estimation of all model parameters even when measurements pertaining to all modelled quantities are unavailable.Imperial Users onl

Give growth and macroeconomic stability in Russia a chance - harden budgets by eliminating nonpayments

The authors analyze the links between Russia's disappointing growth performance in the second half of the 1990s, its costly and unsuccessful stabilization, the macroeconomic meltdown of 1998, and the spectacular rise of non-payments. Non-payments flourished in an environment of fundamental inconsistency between a macroeconomic policy geared at sharp disinflation, and a microeconomic policy of bailing enterprises out through soft budget constraints. Heavy untargeted implicit subsidies flowing through the non-payments system (amounting to 10 percent of GDP annually) have stifled growth, contributed to the August 1998 meltdown, through their impact on public debt, and have made at best a questionable contribution to equity. Dismantling this system must be a top priority, along with promoting enterprise restructuring and growth (by hardening budget constraints) and medium-term macroeconomic stability (by reducing the size of subsidies). Getting the government out of the non-payments system means settling all appropriately controlled budgetary expenditures on time, and in cash, and eschewing spending arrears, thereby setting an example for enterprises, and laying the groundwork for eliminating tax offsets at all levels of government, and insisting on cash tax payments. To stop energy-related subsidies, would require not only that the government pay its own energy bills on time, and in cash, but also that the energy monopolies be empowered to disconnect non-paying clients. This will enable the government to insist that the energy monopolies in turn pay their own taxes in full, and on time.Banks&Banking Reform,Public Sector Economics&Finance,Economic Theory&Research,Payment Systems&Infrastructure,Environmental Economics&Policies,Banks&Banking Reform,Environmental Economics&Policies,Municipal Financial Management,Public Sector Economics&Finance,Economic Theory&Research

Desarrollo y análisis comparativo de concretos premezclados bombeables, con resistencias especificadas a 24h, 3 y 7 días, con y sin uso de acelerante

En el mundo de la ingeniería civil y de la construcción, el concreto toma un papel sumamente importante, debido a que la gran mayoría de las obras construidas en nuestra sociedad actual, son elaboradas principalmente con este material. Una de las características que está tomando mayor fuerza en los últimos tiempos, es la de lograr resistencias requeridas a un plazo mucho más corto que los 28 días convencionales de edad, es decir, lograr obtener concretos de altas resistencias tempranas “ART”. Con los avances tecnológicos de la actualidad, existen insumos que nos pueden ayudar a lograr resistencias elevadas a edades más cortas y con esto lograr de entre muchos de los beneficios de estos tipos concretos, un mayor avance de nuestros proyectos en tiempos menores y de esta forma lograr una pronta entrega de los mismos. En la actualidad existen insumos cuyas propiedades pueden ser muy aprovechables para lograr obtener concretos ART, como los aditivos, especialmente los superplastificantes y acelerantes, además del tipo de cemento cuyas características nos brinden un gran aporte en las resistencias tempranas, como es el cemento tipo HE que la empresa YURA.S.A puso al mercado Arequipeño en estos últimos años. La presente investigación pretende desarrollar y evaluar comparativamente concretos con resistencias especificadas a edades tempranas, que serán evaluadas a las edades de 24 horas, 3 y 7 días, haciendo uso de un aditivo superplastificante y un acelerante, dicha comparación estará dada, por los concretos que contengan acelerante Vs concretos sin acelerante. Para tal fin, se realizaron los siguientes diseños de Mezclas: Concretos con resistencias especificadas de 280 y 420 Kg/cm2, con resistencia a las 24 horas, con acelerante Vs sin acelerante. Concretos con resistencias especificadas de 280 y 420 Kg/cm2, con resistencia a los 3 días, con acelerante Vs sin acelerante. Concretos con resistencias especificadas de 280 y 420 Kg/cm2, con resistencia a los 7 días, con acelerante Vs sin acelerante. Para la preparación de los diseños se utilizó los siguientes materiales; Cemento tipo HE – Yura, aditivo superplastificante (MasterGlenium Scc 3800 - BASF), acelerante (MasterSet ACE 534 - BASF) y también un retardante inicial (MasterSet R770i – BASF), el agregado fino y Agregado grueso provenientes de la Cantera “Vanessa Alejandra II” de la Joya-Arequipa, todos los materiales disponibles en nuestra región de Arequipa. La elaboración de los ensayos y diseños de mezclas, fueron realizados en el laboratorio de control de calidad de la empresa ECOCRET S.A., ubicado en el distrito de cerro colorado, de la ciudad de Arequipa. La finalidad básica de la presente investigación estará basada en la comparación de los concretos ART con resistencias de 280 y 420 Kg/cm2 con acelerante y sin acelerante, para cada edad especificada, evaluadas a través de ensayos que permitan caracterizar las propiedades en estado fresco y endurecido (resistencia a la compresión). De esta manera podremos determinar la elaboración que presenta las mejores propiedades físico-mecánicas y económicas, para concretos especiales con limitaciones en el tiempo de evolución de la resistencia, brindando de esta forma un valioso aporte a la ingeniería civil y la ingeniería de procesos en el desarrollo de los concretos premezclados y prefabricados en nuestra Región de Arequipa. Por lo que, según resultados de la presente investigación y conforme a las características de las mezclas propuestas desarrolladas. Se ha encontrado que, para nuestros diseños de mezclas de concretos ART, resulta que las mezclas elaboradas sin acelerante presentan mejores propiedades en su estado fresco, debido a que estas mezclas tienen un tiempo mayor de trabajabilidad de la mezcla, y resultan más económicas que las mezclas con la inclusión del acelerante. A si mismo cabe señalar que para concretos con resistencias menores a 12 horas, las mezclas con la adición del acelerante presentan mejores propiedades en el desarrollo de resistencias y fraguado de las mezclas

State-of-the-art on evolution and reactivity

This report starts by, in Chapter 1, outlining aspects of querying and updating resources on the Web and on the Semantic Web, including the development of query and update languages to be carried out within the Rewerse project. From this outline, it becomes clear that several existing research areas and topics are of interest for this work in Rewerse. In the remainder of this report we further present state of the art surveys in a selection of such areas and topics. More precisely: in Chapter 2 we give an overview of logics for reasoning about state change and updates; Chapter 3 is devoted to briefly describing existing update languages for the Web, and also for updating logic programs; in Chapter 4 event-condition-action rules, both in the context of active database systems and in the context of semistructured data, are surveyed; in Chapter 5 we give an overview of some relevant rule-based agents frameworks

The relationships between demographic variables and measured burnout among athletic trainers in multiple workplace settings

The purpose of this study was to examine athletic trainer burnout in multiple workplace settings. Burnout was measured in each of eight identified workplace settings. Demographic data was collected to further describe such burnout. No research to date has explored all workplace settings and a clear lack of data existed for five of eight settings. A random sample of 3200 athletic trainers who were members of the national athletic trainers association received an email requesting participation. A total of 766 useable responses were received. The Maslach Burnout Inventory (MBI) was used to measure burnout on three subscales: Emotional Exhaustion, Depersonalization, and Personal Achievement. Scores for each subscale were calculated based on responses to the 22 questions included in the MBI. All items were rated with a seven- point likert scale. Additional questions gathered demographic data including: gender, age, relationship status, certification route, current employment setting, prior employment setting, education level, number of children, supervisor’s status as an athletic trainer, personal recommendation of the profession, hours worked per week, number of years with current employer, and number of years in current setting. A variety of statistical techniques were used to analyze the data, including an analysis of variance to test for differences in burnout between workplace settings. The results demonstrated that a difference exists between workplace settings. For emotional exhaustion, a difference existed between the clinical medical and professional athletics settings. For depersonalization, a difference existed between the clinical medical and administration settings and the clinical medical and clinical rehabilitation settings. No difference was observed for personal achievement. Additional statistical techniques were used to analyze the demographic variables as related to measured burnout, including: analysis of variance, independent t-test, bivariate correlation, pearson’s chi-square, and sensitivity/specificity. Numerous relationships were found to exist between the demographic variables and burnout. Example findings include: females had higher burnout than males, burnout decreased with age, and those without children exhibited more burnout than those with children. If an athletic trainer recommends the profession with or without qualifications, he or she is \u3e90% likely not to be burned out based on an odds ratio 95% confidence interval

Implementación de mejoras en el sistema de respaldo de energía DC para los servicios auxiliares de una subestación de 500 kV

El presente trabajo de suficiencia profesional resumirá la implementación de un sistema paralelo redundante instalado en las 07 salas de control de una subestación de 500 kV, dicha subestación es la principal fuente de alimentación de la Planta Concentradora de Cobre en donde se realizaron los estudios y además ya se tiene antecedentes en la operación de estos equipamientos. El sistema redundante está conformado por un Banco de Baterías, Cargador de Baterías y Tablero de Paralelismo, los cuales brindaran suministro de energía redundante de forma paralela a los Bancos de Baterías y Cargador de Baterías que alimentan las cargas criticas (tableros de servicios auxiliares en 125 Vdc) de una Subestación de 500 kV. El fin de colocar este sistema paralelo es brindar mayor confiablidad a la operación de la planta concentradora de cobre y la Subestación de 500 kV, ya que esta planta ya tuvo incidentes en una de sus salas de baterías donde las cargas criticas quedaron operando sin tener un respaldo de energía, quedando así vulnerable la continuidad de las operaciones. Se brindará metodologías de cálculo de arco eléctrico DC considerando el uso de la normativa NFPA 70E-2018 “Seguridad Eléctrica en Lugares de Trabajo” y los papers publicados por la IEEE “Transactions On Industry Applications”. Con ello también se realizará el análisis de resultados y conocer formas de disminuir la energía incidente (con el uso de tableros de seccionamiento) en lugares donde no se tenga un dispositivo de protección (aguas arriba del interruptor principal) que pueda cortar la evolución del arco eléctrico

Tuning computer vision models with task rewards

Misalignment between model predictions and intended usage can be detrimental for the deployment of computer vision models. The issue is exacerbated when the task involves complex structured outputs, as it becomes harder to design procedures which address this misalignment. In natural language processing, this is often addressed using reinforcement learning techniques that align models with a task reward. We adopt this approach and show its surprising effectiveness across multiple computer vision tasks, such as object detection, panoptic segmentation, colorization and image captioning. We believe this approach has the potential to be widely useful for better aligning models with a diverse range of computer vision tasks.Comment: 11 page

Diseño e implementación de un sistema de identificación de vehículos utilizando redes neuronales artificiales, aplicado a la Universidad Católica De Santa María

El presente trabajo de investigación consiste en el diseño e implementación de un sistema de identificación vehicular aplicable a la Universidad Católica Santa María, ubicada en el distrito de Yanahuara de la provincia de Arequipa. El objetivo principal es integrar en un software 2 metodologías importantes en la actualidad, como son el procesamiento digital de imágenes (PDI) y el reconocimiento óptico de caracteres (OCR), con el fin de contribuir con una alternativa de solución a un problema álgico de nuestra sociedad: la seguridad. De esta manera, se realizó un estudio de técnicas de programación, obteniéndose como resultado el procesamiento morfológico para la detección de placas vehiculares, con resultados de 91% de acierto. De este porcentaje se pasa a la identificación por medio del entrenamiento de RNA, con resultados de 100% y tiempos de respuesta de 1.2 segundos, los cuales son mejores que con el método convencional: coeficiente de correlación de Pearson (86%), y que tiene tiempos promedio de 5.5 segundos. Este software es aplicable a cualquier cámara con resolución mínima de 480p, sin necesidad de hardware con costos adicionales, lo que lo hace una alternativa más económica y versátil respecto a otras del mercado. Palabras Clave: procesamiento digital de imágenes, reconocimiento óptico de caracteres, red neuronal artificial, procesado morfológico.Tesi