Statistical mechanics of gene competition

Statistical mechanics has been applied to a wide range of systems in physics, biology, medicine and even anthropology. This theory has been recently used to model the complex biochemical processes of gene expression and regulation. In particular, genetic networks offer a large number of interesting phenomena, such as multistability and oscillatory behaviour, that can be modelled with statistical mechanics tools. In the first part of this thesis we introduce gene regulation, genetic switches, and the colonization of a spatially structured media. We also introduce statistical mechanics and some of its useful tools, such as the master equation and mean- field theories. We present simple examples that are both pedagogical and also set the basis for the study of more complicated scenarios. In the second part we consider the exclusive genetic switch, a fundamental example of genetic networks. In this system, two proteins compete to regulate each other's dynamics. We characterize the switch by solving the stationary state in different limits of the protein binding and unbinding rates. We perform a study of the bistability of the system by examining its probability distribution, and by applying information theory techniques. We then present several versions of a mean field theory that offers further information about the switch. Finally, we compute the stationary probability distribution with an exact perturbative approach in the unbinding parameter, obtaining a valid result for a wide range of parameters values. The techniques used for this calculation are successfully applied to other switches. The topic studied in the third part of the thesis is the propagation of a trait inside an expanding population. This trait may represent resistance to an antibiotic or being infected with a certain virus. Although our model accounts for different examples in the genetic context, it is also very useful for the general study of a trait propagating in a population. We compute the speed of expansion and the stationary population densities for the invasion of an established and an expanding population, finding non-trivial criteria for speed selection and interesting speed transitions. The obtained formulae for the different wave speeds show excellent agreement with the results provided by simulations. Moreover, we are able to obtain the value of the speeds through a detailed analysis of the populations, and establish the requirements for our equations to present speed transitions. We finally apply our model to the propagation in a position-dependent fitness landscape. In this situation, the growth rate or the maximum concentration depends on the position. The amplitudes and speeds of the waves are again successfully predicted in every case

Diseño y construcción de un carbonatador de inyección como parte de una línea de proceso para la producción de cerveza artesanal

El objetivo de este trabajo fue diseñar y construir un carbonatador de inyección como parte de una línea de proceso para la producción de cerveza artesanal. Se establecieron las variables de proceso presión y temperatura, siguiendo los requerimientos del parámetro carbonatación de la norma NTE INEN 2262 “Bebidas alcohólicas. Cerveza. Requisitos”. El diseño del cuerpo del tanque, sus principales accesorios y la selección del material de construcción se basaron en el código ASME Sección VIII: Reglas para la construcción de recipientes a presión, División I y la Sección II Materiales Parte D Propiedades del mismo código. Adicionalmente, se construyó un aparato para verificar el nivel de carbonatación bajo los lineamientos de la norma NTE INEN 2324 “Bebidas alcohólicas para verificar el nivel de carbonatación. Se determinó una presión máxima de 30 psi y una temperatura entre 5 y 25 grados Celsius. El tanque diseñado tiene un ancho de pared de 3mm, 40 litros de capacidad, cabezales elipsoidales y una válvula de alivio Swagelok, regulable, para evitar explosiones debido a excesos de presión; opera hasta una presión máxima sugerida de 30 psi, verificados mediante pruebas hidrostáticas. Como resultado de la carbonatación, se obtuvo 2,45 vol. de dióxido de carbono por litro de cerveza, valor que está dentro del rango permitido para carbonatación por la norma NTE INEN 2262. Finalmente, este trabajo se puede ampliar estudiando el uso de un sistema de control automático o un sistema de agitación y se recomienda el uso del tanque para carbonatar diferentes tipos de bebidas.The objective of this work was to design and build an injection carbonator as part of a process line for the production of craft beer. The pressure and temperature process variables were established, following the requirements of the carbonation parameter of the NTE INEN 2262 standard “Alcoholic beverages. Beer. Requirements". The design of the tank body, its main accessories and the selection of the construction material were based on the ASME code Section VIII: Rules for the construction of pressure vessels, Division I and Section II Materials Part D Properties of the same code. Additionally, a device was built to verify the carbonation level under the guidelines of the NTE INEN 2324 standard "Alcoholic beverages to verify the carbonation level. A maximum pressure of 30 psi and a temperature between 5 and 25 degrees Celsius was determined. The designed tank has a 3mm wall width, 40 liter capacity, ellipsoidal heads and an adjustable Swagelok relief valve to avoid explosions due to excess pressure; operates up to a pressure suggested maximum 30 psi, verified by hydrostatic testing. As a result of carbonation, 2.45 vol. of carbon dioxide per liter of beer, a value that is within the range allowed for carbonation by the NTE INEN 2262 standard. Finally, this work can be expanded by studying the use of an automatic control system or a stirring system. It is recommended to use the tank to carbonate different types of drinks

Speed of Invasion of an Expanding Population by a Horizontally Transmitted Trait

Range expansions are a ubiquitous phenomenon, leading to the spatial spread of genetic, ecological, and cultural traits. While some of these traits are advantageous (and hence selected), other, nonselected traits can also spread by hitchhiking on the wave of population expansion. This requires us to understand how the spread of a hitchhiking trait is coupled to the wave of advance of its host population. Here, we use a system of coupled Fisher-Kolmogorov-Petrovsky-Piskunov (F-KPP) equations to describe the spread of a horizontally transmitted hitchhiking trait within a population as it expands. We extend F-KPP wave theory to the system of coupled equations to predict how the hitchhiking trait spreads as a wave within the expanding population. We show that the speed of this trait wave is controlled by an intricate coupling between the tip of the population and trait waves. Our analysis yields a new speed selection mechanism for coupled waves of advance and reveals the existence of previously unexpected speed transitions

Molecular detection and characterization of hemoplasmas in the pudu (Pudu Puda), a native CERVID from CHILE

8 Pág. Centro de Investigación en Sanidad Animal (CISA)Hemotropic mycoplasmas cause hemolytic anemia in a variety of wild and domestic mammals. Despite growing evidence about their widespread presence and genetic diversity in wildlife, their presence has never been investigated in Chilean artiodactyls. We aimed to describe the presence and diversity of hemoplasmas in pudus (Pudu puda), a small cervid native to Chile. Hemoplasma infection was assessed in blood samples from 43 wild and 33 captive pudus from central and southern Chile by direct sequencing of the 16S rRNA gene. We detected hemoplasmas in 13%, with no statistical differences between wild (19%) and captive animals (6%). A sequence closely related to Mycoplasma ovis was present both in wild (14%) and captive (6%) pudus. Two previously undescribed sequences, classified in a clade including hemoplasmas from carnivores, were found in one wild pudu each. This study presents the first evidence of the presence of M. ovislike organisms in Chile and of the susceptibility of pudus to infection with hemoplasmas. Further research is needed to understand the pathologic consequences of this pathogen for pudus, its effects at the population level, and their potential impact on the health small ruminants and other wildlife species in Chile.Peer reviewe

Splicing Machinery is Dysregulated in Pituitary Neuroendocrine Tumors and is Associated with Aggressiveness Features

Pituitary neuroendocrine tumors (PitNETs) constitute approximately 15% of all brain tumors, and most have a sporadic origin. Recent studies suggest that altered alternative splicing and, consequently, appearance of aberrant splicing variants, is a common feature of most tumor pathologies. Moreover, spliceosome is considered an attractive therapeutic target in tumor pathologies, and the inhibition of SF3B1 (e.g., using pladienolide-B) has been shown to exert antitumor effects. Therefore, we aimed to analyze the expression levels of selected splicing-machinery components in 261 PitNETs (somatotropinomas/non-functioning PitNETS/corticotropinomas/prolactinomas) and evaluated the direct effects of pladienolide-B in cell proliferation/viability/hormone secretion in human PitNETs cell cultures and pituitary cell lines (AtT-20/GH3). Results revealed a severe dysregulation of splicing-machinery components in all the PitNET subtypes compared to normal pituitaries and a unique fingerprint of splicing-machinery components that accurately discriminate between normal and tumor tissue in each PitNET subtype. Moreover, expression of specific components was associated with key clinical parameters. Interestingly, certain components were commonly dysregulated throughout all PitNET subtypes. Finally, pladienolide-B reduced cell proliferation/viability/hormone secretion in PitNET cell cultures and cell lines. Altogether, our data demonstrate a drastic dysregulation of the splicing-machinery in PitNETs that might be associated to their tumorigenesis, paving the way to explore the use of specific splicing-machinery components as novel diagnostic/prognostic and therapeutic targets in PitNETs

El sistema financiero del siglo xxi a partir de la Ley 45 de 1990

La Ley 45 de 1990 representa un momento estelar en la historia de la legislación financiera de Colombia. Pero abarcó mucho más: reguló la actividad aseguradora, incursionó en el contrato de seguro, reguló el sistema previsional y delineó el régimen bursátil. Así mismo, anticipó lineamientos de lo que sería, un año después, la consagración de tales actividades -financiera, aseguradora, bursátil y previsional- como de rango constitucional. Este libro recoge las reflexiones de expertos sobre las diversas temáticas abordadas en dicha ley, con la visión enriquecida derivada del transcurso de 20 años, de varias legislaciones adicionales y de algunas crisis nacionales y foráneas. Escrutar en su veintenario es un ejercicio válido y oportuno, tanto más como que al haber renovado los arquetipos de la legislación precedente, sirvió además como referente de empeños de enmienda normativas de otros países de la región y de los organismos multilaterales

Melatonin protects rats from radiotherapy-induced small intestine toxicity

Radiotherapy-induced gut toxicity is among the most prevalent dose-limiting toxicities following radiotherapy. Prevention of radiation enteropathy requires protection of the small intestine. However, despite the prevalence and burden of this pathology, there are currently no effective treatments for radiotherapy-induced gut toxicity, and this pathology remains unclear. The present study aimed to investigate the changes induced in the rat small intestine after external irradiation of the tongue, and to explore the potential radio-protective effects of melatonin gel. Male Wistar rats were subjected to irradiation of their tongues with an X-Ray YXLON Y.Tu 320-D03 irradiator, receiving a dose of 7.5 Gy/day for 5 days. For 21 days post-irradiation, rats were treated with 45 mg/day melatonin gel or vehicle, by local application into their mouths. Our results showed that mitochondrial oxidative stress, bioenergetic impairment, and subsequent NLRP3 inflammasome activation were involved in the development of radiotherapy-induced gut toxicity. Oral treatment with melatonin gel had a protective effect in the small intestine, which was associated with mitochondrial protection and, consequently, with a reduced inflammatory response, blunting the NF-κB/NLRP3 inflammasome signaling activation. Thus, rats treated with melatonin gel showed reduced intestinal apoptosis, relieving mucosal dysfunction and facilitating intestinal mucosa recovery. Our findings suggest that oral treatment with melatonin gel may be a potential preventive therapy for radiotherapy-induced gut toxicity in cancer patients.This study was partially supported by grant no. SAF2009-14037 from the Spanish Ministry of Economy and Competitivity (MINECO), GREIB.PT_2010_04 from the CEIBiotic Program of the University of Granada, Spain, and CTS-101 from the Consejería de Innovación, Ciencia y Empresa, Junta de Andalucía, Spain

Cátedra abierta de la interculturalidad en territorios de paz : capítulo 1: semillas, alimentos y comida. Una lectura intercultural

CD-T 306.4 S55; 146 p CD-T 306.4 S55c; 142 pEl proyecto catedra abierta de la interculturalidad de la Universidad Libre construye escenarios de paz para la construcción de nuestra identidad nacional en tres municipios : La Virginia, Mistrató, Pereira; hoy se logra llegar a estos tres municipios y con estos se inicia el camino de la mano de niñas y niños de centros educativas urbanos y rurales; el sector educativo caracterizó el inicio histórico y el tema pre-texto fue: las semillas, los alimentos y la comida, tema qué esta propuesto desde el primer encuentro intercultural realizado en el municipio de Mistrató, con la participación activa de comunidades nativas y del fundador de la catedra el TAITA JAVIER CALAMBAS, de la comunidad indígena MISAK del Cauca. El proceso de la catedra se orientó con la metodología MARDIC, la cual propicio la participación activa de grupos organizados denominados grupos focales.Universidad Libre Seccional Pereir

International lower limb collaborative (INTELLECT) study: a multicentre, international retrospective audit of lower extremity open fractures

Trauma remains a major cause of mortality and disability across the world1, with a higher burden in developing nations2. Open lower extremity injuries are devastating events from a physical3, mental health4, and socioeconomic5 standpoint. The potential sequelae, including risk of chronic infection and amputation, can lead to delayed recovery and major disability6. This international study aimed to describe global disparities, timely intervention, guideline-directed care, and economic aspects of open lower limb injuries