Butane-1,4-diyl bis-(pyridine-3-carboxyl-ate)

Mol­ecules of the title compound (alternative name: butane-1,4-diyl dinicotinate), C16H16N2O4, lie on a inversion centre, located at the mid-point of the central C—C bond of the aliphatic chain, giving one half-mol­ecule per asymmetric unit. The butane chain adopts an all-trans conformation. The dihedral angle between the mean plane of the butane-3-carboxyl­ate group [for the non-H atoms, maximum deviation = 0.0871 (15) Å] and the pyridine ring is 10.83 (7)°. In the crystal, mol­ecules lie in planes parallel to (122). The structure features weak π–π inter­actions with a centroid–centroid distance of 3.9281 (11) Å

¿La Internet ecualiza el sistema electoral mexicano? El caso de los candidatos independientes en 2015

Se analiza el tema de las candidaturas independientes, y se indica que el triunfo de los seis candidatos que compitieron bajo esta modalidad en las elecciones intermedias de 2015 coincidió con varios factores: un discurso antipartidos políticos, la incertidumbre de la asignación de recursos y el uso inteligente de los nuevos medios sociales y de la Internet. Se hace una breve exploración entre las posibilidades que brinda la web 2.0 en tanto sus cualidades para la interacción y la ventaja que esto representó para las candidaturas independientes que lo aprovecharon.ITESO, A.C

Análisis energético y exergético de una planta de cogeneración del sector azucarero asistida por colectores solares

En este trabajo se presenta un análisis de una planta de cogeneración de la industria azucarera de Colombia, aprovechando una fuente de energía renovable a través de colectores solares. Este análisis se realiza con el fin de aumentar la temperatura del fluido de trabajo a la entrada de los generadores de vapor, y así reducir las diferencias de temperatura entre la entrada y la salida de estos dispositivos, logrando una reducción en el consumo de combustible. La investigación se desarrolla mediante un análisis energético y exergético con base en un modelo termodinámico que representa la operación de la planta en régimen permanente. Se evalúa la vinculación de dos tipos de colectores solares: Cilindro-Parabólico (CCP) y Lineal-Fresnel (CLF), cada uno modelado de manera independiente. La inclusión de los sistemas de recolección solar en el ciclo de cogeneración de la planta de la industria azucarera presenta posibilidades de mejora en el proceso, ya que aumenta tanto su eficiencia energética como su eficiencia exergética, debido a la disminución en el consumo de combustible. Los resultados muestran que aumenta la eficiencia energética de un 68,71% a un 75% aproximadamente con los sistemas de recolección solar; 74,86% con CCP y 75,17 % con CLF. En cuanto a la eficiencia exergética, se pasa de un 46,47 % a 50,7 % con CCP y 50,83 % con CLF, disminuyendo hasta un 2,1% de exergía destruida en la planta. En consumo de combustible, se logra una disminución hasta del 8,6 % con CLF y del 8,35 % con el CCP, reflejando un ahorro de hasta 5000 toneladas de combustible al año

Discrimination in the provision of social services to the poor: a field experimental study

We use an experimental field approach to understand better the pro-social preferences andbehavior of both individuals involved in the provision of social services (public servants) and the behavior of those potential beneficiaries, the poor. We conducted field experiments using the Dictator, Ultimatum, Trust and Third Party Punishment games, and a newly designed Distributive Dictator Game. With these, we want to understand the traits and mechanisms that guide pro-sociality including altruism, reciprocal altruism, reciprocity, trust, fairness, inequity aversion, and altruistic (social) punishment. We recruited in Bogotá, Colombia more than 500 public servants and beneficiaries from welfare programs associated with health, education, childcare and nutrition. The overall results replicate the patterns of previous studies with these experimental designs, that is, individuals showed a preference for fair outcomes, positive levels of trust and reciprocity, and willingness to punish -at a personal cost, unfair outcomes if against themselves or if against third parties. By using more information about our participants we were able however to explain the observed variations in these behaviors. The results provide evidence that the poor trigger more pro-social behavior from all citizens including public servants, but the latter show more strategic generosity by graduating their pro-social behavior towards the poor depending on attributes of the beneficiaries or recipients of offers in these games. We observed a bias in favor of women and households with more number of dependents, but discriminatory behavior against particularly stigmatized groups in society such as ex-combatants from the political conflict, or street recyclers2.Distributive dictator game, Dictator Game, Ultimatum game, Trust Game, Third-Party Punishment game, pro-social behavior, public officials, field experiments.

Propane-1,3-diyl bis­(pyridine-4-carboxyl­ate)

The title compound. C15H14N2O4, (I), has a gauche–gauche (O/C/C/C—O/C/C/C or GG) conformation and is a positional isomer of propane-1,3-diyl bis­(pyridine-3-carboxyl­ate), (II). The mol­ecule of (I) lies on a twofold rotation axis, which passes through the central C atom of the aliphatic chain, giving one half-mol­ecule per asymmetric unit. There is excellent agreement of the geometric parameters of (I) and (II). The most obvious differences between them are the O/C/C/C—O/C/C/C torsion angles [56.6 (2)° in (I) and 174.0 (3)/70.2 (3)° in (II) for GG and TG conformations, respectively] and the dihedral angle between the planes of the aromatic rings [80.3 (10)° in (I) and 76.5 (3)° in (II)]. The crystal structure is stabilized by weak C—H ... N and C—H ... O hydrogen bonding

Prediction for the interferometric shape of the first black hole photon ring

Black hole images are theoretically predicted (under mild astrophysical assumptions) to display a stack of lensed "photon rings" that carry information about the underlying spacetime geometry. Despite vigorous efforts, no such ring has been observationally resolved thus far. However, planning is now actively under way for space missions targeting the first (and possibly the second) photon rings of the supermassive black holes M87* and Sgr A*. In this work, we study interferometric photon ring signatures in time-averaged images of Kerr black holes surrounded by different astrophysical profiles. We focus on the first, most easily accessible photon ring, which has a larger width-to-diameter ratio than subsequent rings and whose image consequently lacks a sharply defined diameter. Nonetheless, we show that it does admit a precise angle-dependent diameter in visibility space, for which the Kerr metric predicts a specific functional form that tracks the critical curve. We find that a measurement of this interferometric ring diameter is possible for most astrophysical profiles, paving the way for precision tests of strong-field general relativity via near-future observations of the first photon ring.Comment: 16 pages, 6 figures. V2: Minor changes to match the published versio

Evaluación del grado de contaminación por plaguicidas organofosforados en cultivos de cebolla (allium fistulosum) en suelo y agua de escorrentía en el corregimiento de la Florida de la ciudad de Pereira

En el estudio realizado en el presente trabajo se describe el proceso para la determinación de la presencia de los plaguicidas organofosforados aplicados en los cultivos de cebolla de la finca “Bella Vista”, ubicada aproximadamente a 1.5Km del corregimiento de la Florida y a 200m del río Otún. Para ello, se propone un método para el análisis de muestras de agua y de suelo, mediante la técnica de cromatografía de gases con detector de captura electrónica (ECD)