An Attempted Synthesis of a Menadione Derivative via a Diels-Alder Reaction

With menadione and cyclopentadiene as starting materials, a menadione-cyclopentadiene adduct was synthesized via a Diels-Alder reaction. This reaction serves as the first step in a pathway to synthesize a menadione-safranal derivative that could potentially have antioxidant activity

Homeownership Rate and Other House Price Determinants Impacts on New House Prices in Colombia

Homeownership remains a preferred form of tenancy in different parts of the world. The attractions of security, stability, investment potential and a sense of pride outweigh the fear of price instability. For this reason, the Colombian government has encouraged in recent years, various demand policies that have sought to promote the increase in the number of homeowners. However, these ideas could have a severe impact on prices in the real estate market. Therefore, this study seeks to examine the effect of homeownership rate on new house prices in an emerging country with low real estate ownership, credit restrictions and average per capita income. The study uses panel data model to examine the influence of housing tenancy and other variables on the variation of housing prices in Colombia. Data were obtained from various sources including the Central Bank of Colombia, Financial Superintendence of Colombia, and National Administrative Department of Statistics of Colombia. The results show that homeownership rates have a positive effect on the price of new homes, which supports the hypothesis of the research. The population growth of the cities is the factor that is most relevant when explaining the price variations

The replicator coalescent

We consider a stochastic model, called the replicator coalescent, describing a system of blocks of $k$ different types which undergo pairwise mergers at rates depending on the block types: with rate $C_{i,j}$ blocks of type $i$ and $j$ merge, resulting in a single block of type $i$. The replicator coalescent can be seen as generalisation of Kingman's coalescent death chain in a multi-type setting, although without an underpinning exchangeable partition structure. The name is derived from a remarkable connection we uncover between the instantaneous dynamics of this multi-type coalescent when issued from an arbitrarily large number of blocks, and the so-called replicator equations from evolutionary game theory. By dilating time arbitrarily close to zero, we see that initially, on coming down from infinity, the replicator coalescent behaves like the solution to a certain replicator equation. Thereafter, stochastic effects are felt and the process evolves more in the spirit of a multi-type death chain.Comment: 1 figur

Adverse events of ERCP at San José Hospital of Bogotá (Colombia)

Endoscopic retrograde cholangiopancreatography (ERCP) has become the preferred treatment method for hepatobiliary and pancreatic disease. Despite technological progress this technique continues to account for the greatest morbidity and mortality caused by digestive endoscopic procedures. ERCP carries a risk of pancreatitis, perforation, hemorrhage, cholangitis and cardiopulmonary events occurring in upto 10% of patients in referral centers, implying a mortality of up to 1%, not including therapeutic failures or the need for re-intervention. A greater mortality rate has been demonstrated in prospective studies rather than in retrospective studies, but overall, the number of complications described in the literature is much lower than the number of complications that actually occur. A descriptive prospective study was conducted at San José Hospital from April 1, 2006 to April 30, 2007 in patients who underwent an ERCP and had a 1-month follow-up. A total of 381 patients were included; 9 (2.3%) were excluded, and of the remaining 372 there was an overall success in 79.6% of cases, 8.3% had a second intervention, 7.6% developed complications (pancreatitis, perforation, hemorrhage, cholangitis, pain, intolerance to sedatives, and cardiopulmonary events), and 4.3% were failed ERCP studies. The mortality rate of the ERCP procedure was 0.8%. ERCP-related complications were determined at a teaching center, and this suggests the need to implement centers of excellence in order to improve the efficacy of the procedure

Assessment of the splitting-tensile strength of ZP-306 steel fiber reinforced concrete

El concreto reforzado con fibras de acero (CRFA) es un material con gran potencial de uso en viviendas de concreto de baja altura, ya que la capacidad de resistencia de los muros está controlada por la resistencia a tensión diagonal. El artículo presenta los resultados de un estudio experimental para caracterizar la resistencia a tensión por compresión diametral del CRFA que es elaborado con fibra ZP-306 y con concretos locales. El programa experimental incluyó el ensayo de 52 especímenes en forma de cilindros. En el estudio se discuten los modelos de predicción disponibles y se realiza un análisis estadístico para comparar los resultados calculados con los datos medidos. Con base en las tendencias de los resultados experimentales, se proponen ecuaciones para estimar los parámetros que describen la envolvente del comportamiento esfuerzo-deformación del CRFA sometido a esfuerzos de compresión diametral. Las ecuaciones se han desarrollado en un formato versátil para ser incluidas en un reglamento de diseño. Abstract Steel fibers reinforced concrete (SFRC) is a material with great potential to be used in low-rise concrete housing because the strength capacity of the walls is controlled by diagonal tension strength. The paper shows the results of an experimental study intended to characterize splitting-tensile strength of SFRC made of both ZP-306 fiber and local concrete. The experimental program included the tests of 52 cylindrical-shaped specimens. The study discusses the available predictive models and shows a statistical analysis to compare the predicted results with measured data. Based on trends of the experimental results, equations to estimate the parameters describing the backbone of the stress-strain behavior of SFRC under splitting-tensile strength are proposed. The equations have been developed in a versatile format to be included in a design code

Laboratório de citogenética vegetal Embrapa Recursos Genéticos e Biotecnologia: normas de utilização e manutenção.

O Laboratório de Citogenética Vegetal foi criado com o intuito de realizar pesquisas básicas de caracterização de recursos genéticos vegetais, que auxiliam direta ou indiretamente a coleta, multiplicação, conservação e consequentemente disponibiliza dados ao melhorista que poderá fazer uso imediato ou futuro deste recurso. Os estudos incluem: análise do número e morfologia de cromossomos; análise do comportamento meiótico; estudos de poliploidia; estudos de comportamento e estabilidade cromossômica; análise da viabilidade de pólen; identificação de apomixia; identificação de casmo/cleistogamia; estudos de hibridação intra/interespecífica e intergenérica; identificação de auto/alogamia; desenvolvimento e adaptação de metodologias para análise citogenética e reprodutiva em germoplasma vegetal. Além disso, o laboratório oferece sua infraestrutura está para o treinamento de recursos humanos em caracterização citogenética, através de estágios e cursos que são oferecidos conforme a demanda

Reflexión epistemológica de experimentos cruciales

This work is a product of analysis found from a search about obstacles identified in crucial experiments in the history of physics and its relationship to the way in which they are currently taught. From an epistemological analysis we propose an alternative way of generating new scenarios for understanding a theory without resorting to traditional processes. The solution to the problems found in this research, from the authors point of view, have an answer in the philosophy and epistemology of science .Este trabajo es producto del análisis encontrado a partir de una búsqueda de obstáculos identificados en experimentos cruciales en la historia de la física y su relación con la forma en que se enseñan actualmente. A partir de análisis epistemológicos se propone una manera alternativa de generar nuevos escenarios para la comprensión de una teoría sin recurrir a los procesos tradicionales.  La solución a los problemas que se encontraron en esta investigación, desde el punto de vista de los autores; tienen respuesta en la filosofía y epistemología de la ciencia

Software to Assist Visually Impaired People During the Craps Game Using Machine Learning on Python Platform

Pattern recognition is a prominent area of research in computer vision, where different methods have been proposed in the last 50 years. This work presents the development of a Python API to identify the result of two six-sided dice used in the game called “Craps” as a no-controlled environment to help visually impaired people. The software is structured in four stages. The first one is capturing images through a device with a digital camera connected to the web via IP address. The second stage corresponds to the captured image processing; it is necessary to establish a standard image size and resize and equalize the digitized image. The third stage seeks to segment the object of study by artificial vision techniques to identify the result of the dice after being thrown. Finally, the fourth stage is to interpret the result and play it through a speaker. The expected possible result is a system that integrates the four stages mentioned above through an intuitive and accessible low-cost Python API, mainly aimed at visually impaired people