A case of the Rodriguez Villegas conjecture

Let L be a number field and let E be any subgroup of the units O_L^* of L. If rank(E) = 1, Lehmer's conjecture predicts that the height of any non-torsion element of E is bounded below by an absolute positive constant. If rank(E) = rank(O_L^*), Zimmert proved a lower bound on the regulator of E which grows exponentially with [L:Q]. Fernando Rodriguez Villegas made a conjecture in 2002 that "interpolates" between these two extremes of rank. Here we prove a high-rank case of this conjecture. Namely, it holds if L contains a subfield K for which [L:K] >> [K:Q] and E contains the kernel of the norm map from O_L^* to O_K^*

Effects of Soil Silicon Amendment and Nitrogen Levels on Rice Insect Pest Complex

Rice plants are consistently subjected to various pressures by insect pests throughout the growing season. The main insect pest complex reported in Louisiana are the rice water weevil (major early-season insect pest), fall armyworm (sporadic early-season pest), sugarcane borer and rice stalk borer (long- established but sporadic stem boring pests), Mexican rice borer (an invasive stem-boring pest), and rice stink bug (major late-season pest). Soil silicon amendment has been shown to enhance plant resistance against herbivorous pests. Rice is a typical silicon-accumulating graminaceous crop. Field and greenhouse experiments were conducted from 2015 to 2017 to investigate the effects of soil silicon amendment and nitrogen levels on the rice insect pest complex In Louisiana. In the greenhouse, we found that force required to penetrate rice stem was higher on silicon-treated rice plants compared to untreated plants. Total phenolic content on the other hand, decreased when nitrogen rate was increased. In the field experiment, the effects of soil silicon amendment on rice water weevil densities, whitehead incidences, stink bug population, and yields were found to be weaker than the effects of nitrogen fertilization. Furthermore, separate field experiments were conducted in 2016 and 2017 to investigate the effects of silicon fertilization and rice cultivars on the rice insect pests. Results showed reductions in weevil larval densities in silicon treated plots compared to untreated plots in one core sampling in 2016. Similarly, higher yields were observed in silicon treated plots compared to untreated plots in 2016. Silicon amendment did not affect whitehead incidences and rice stink bug densities in both years. The levels of infestations of rice water weevil, stem borers, and rice stink bugs were also were also found to vary among the rice cultivars evaluated in the study. Despite the weak effect of silicon on insect pests in this study, silicon could still play an important role in rice production considering the positive effects on yield and documented effects on disease suppression

Pathways to Economic Outcomes and the Impact of Health: Comparing Hispanic and Non-Hispanic Adults after Foster Care

Abstract This study examines the financial outcomes in adulthood of Hispanics (N = 87) and White (Non-Hispanic, N = 498) persons placed in foster care during childhood. It uses the Casey Family Programs National Alumni Study (CFPNAS) database. Path models including predictors such as gender, education, having a partner, preparation for leaving care, and problem characteristics yielded predominantly similar effects for Hispanic and White Non-Hispanic respondents. The direct effect of physical and mental health conditions such as physical or learning disability, visual or hearing impairments, or DSM disorders more strongly predicted negative outcomes for White (Non-Hispanic) respondents than for Hispanic ones

Caracterización de ruido y vibraciones de un Chiller

Se ha realizado un estudio del ruido acústico al interior del laboratorio de ensayos dinámicos y materiales fibro-reforzados de la Escuela de Ingeniería Mecánica de la Universidad del Valle, que incluye el estudio de una de las fuentes principales de esta emisión acústica conocida como chiller, cuyo modelo es SIC-5A-P. Este es el encargado de refrigerar el aceite hidráulico de la máquina de ensayos dinámicos adyacente. El uso de la refrigeración es imprescindible debido a las altas presiones que se alcanzan en los pistones hidráulicos durante los ensayos con probetas. Las mediciones de presión acústica para la predicción del campo acústico fueron realizadas con micrófono y sonómetro tipo 2 para aplicaciones generales siguiendo los lineamientos de la norma NTC 5793. La comparación de los niveles aceptados por norma dentro del laboratorio se llevó a cabo con la resolución 627 de 2006, del Ministerio de Ambiente, Vivienda y Desarrollo Territorial, artículo 9, donde se establecen los estándares máximos permisibles de niveles de emisión de ruido en dB(A). Los resultados indican que se supera este nivel durante el día aproximadamente por 10 dB(A) cuando la máquina de ensayos en el laboratorio está en funcionamiento. Con la intención de evaluar el ruido encaminado a su reducción, se tomaron datos de vibración estructural, justo sobre la carcasa del chiller durante su funcionamiento, para calcular su potencia a 125 Hz, además se analizó la repuesta en frecuencia de dos de sus caras, inclusive se realizaron mediciones acústicas al interior del laboratorio. Los análisis de las señales adquiridas de velocidad de vibración muestran concentraciones de energía a 48.8 Hz, 61 Hz y 122.1 Hz aproximadamente, que corresponden a las frecuencias de vibración de los componentes internos del chiller: compresor, bomba y 5° armónico del ventilador respectivamente.PregradoINGENIERO(A) EN MECANIC

Environment and society ¿an ethical commitment to the accounting profession?

Este trabajo presenta una aproximación conceptual a los dilemas éticos que enfrenta el profesional contable: la ética ambiental y la responsabilidad social; Partiendo de la interpretación de algunas teorías relacionadas para generar una reflexión sobre el protagonismo y compromiso de éste, como defensor, precursor y respetuoso de los derechos naturales y humanos. Muchos contadores han orientado sus esfuerzos a procesar y reportar información económico-financiera, olvidando dar cuenta de los recursos naturales que emplean las entidades y su impacto para el desarrollo sustentable y la calidad de vida. Esta investigación tiene un enfoque cualitativo, empleando el método inductivo y el análisis de contenido, con la cual los autores tratan de mostrar cómo el profesional de la contabilidad debe ser consciente, que para ser ciudadano ambientalmente responsables, se debe restituir y transmitir el legado dejado por la naturaleza, en las condiciones originales, y de ser posible, un poco mejor.This paper presents a conceptual approach to the ethical dilemmas faced by the accounting professional: environmental ethics and social responsibility; Starting from the interpretation of some related theories to generate a reflection on the protagonism and commitment of the latter, as a defender, precursor and respectful of natural and human rights. Many accountants have oriented their efforts to process and report economic-financial information, forgetting to account for the natural resources used by the entities and their impact for sustainable development and quality of life. This research has a qualitative approach, using the inductive method and the content analysis, with which the authors try to show how the accounting professional should be aware, that to be an environmentally responsible citizen, the legacy left must be restored and transmitted by nature, in the original conditions, and if possible, a little better

Densities of short uniform random walks

We study the densities of uniform random walks in the plane. A special focus is on the case of short walks with three or four steps and less completely those with five steps. As one of the main results, we obtain a hypergeometric representation of the density for four steps, which complements the classical elliptic representation in the case of three steps. It appears unrealistic to expect similar results for more than five steps. New results are also presented concerning the moments of uniform random walks and, in particular, their derivatives. Relations with Mahler measures are discussed.Comment: 32 pages, 9 figure

Pan-genome sequence analysis using Panseq: an online tool for the rapid analysis of core and accessory genomic regions

<p>Abstract</p> <p>Background</p> <p>The pan-genome of a bacterial species consists of a core and an accessory gene pool. The accessory genome is thought to be an important source of genetic variability in bacterial populations and is gained through lateral gene transfer, allowing subpopulations of bacteria to better adapt to specific niches. Low-cost and high-throughput sequencing platforms have created an exponential increase in genome sequence data and an opportunity to study the pan-genomes of many bacterial species. In this study, we describe a new online pan-genome sequence analysis program, Panseq.</p> <p>Results</p> <p>Panseq was used to identify <it>Escherichia coli </it>O157:H7 and <it>E. coli </it>K-12 genomic islands. Within a population of 60 <it>E. coli </it>O157:H7 strains, the existence of 65 accessory genomic regions identified by Panseq analysis was confirmed by PCR. The accessory genome and binary presence/absence data, and core genome and single nucleotide polymorphisms (SNPs) of six <it>L. monocytogenes </it>strains were extracted with Panseq and hierarchically clustered and visualized. The nucleotide core and binary accessory data were also used to construct maximum parsimony (MP) trees, which were compared to the MP tree generated by multi-locus sequence typing (MLST). The topology of the accessory and core trees was identical but differed from the tree produced using seven MLST loci. The Loci Selector module found the most variable and discriminatory combinations of four loci within a 100 loci set among 10 strains in 1 s, compared to the 449 s required to exhaustively search for all possible combinations; it also found the most discriminatory 20 loci from a 96 loci <it>E. coli </it>O157:H7 SNP dataset.</p> <p>Conclusion</p> <p>Panseq determines the core and accessory regions among a collection of genomic sequences based on user-defined parameters. It readily extracts regions unique to a genome or group of genomes, identifies SNPs within shared core genomic regions, constructs files for use in phylogeny programs based on both the presence/absence of accessory regions and SNPs within core regions and produces a graphical overview of the output. Panseq also includes a loci selector that calculates the most variable and discriminatory loci among sets of accessory loci or core gene SNPs.</p> <p>Availability</p> <p>Panseq is freely available online at <url>http://76.70.11.198/panseq</url>. Panseq is written in Perl.</p