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Search Results: 1 - 10 of 16086 matches for " PEDRO; URRUTIA "
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Cytogenetics of Chilean angiosperms: Advances and prospects
JARA-SEGUEL,PEDRO; URRUTIA,JONATHAN;
Revista chilena de historia natural , 2012, DOI: 10.4067/S0716-078X2012000100001
Abstract: cytogenetic data on chilean angiosperms have been reported since at least eight decades ago; however, much of this information is disperse in diverse sources and is not readily available as a comprehensive document that allows having a general vision on advances and gaps in this matter. the goal of this paper is to summarize the advances and prospets on cytogenetic studies of the chilean angiosperms based on compiled publications from 1929 to 2010. we found 78 publications supplied by four groups of chilean researchers and some foreign specialists. cytogenetic data have been reported for 139 chilean angiosperm species (2.8 % of the total), which belong to 58 genera and 34 families. during 2001-2010 there was an increase in the number of publications, being available 40 reports including 95 additional species. based on these data, we hope that such a trend can be maintained in the next decade if the current research groups and young specialists continue to be interested in the study of native plants.
Cytogenetics of Chilean angiosperms: Advances and prospects Citogenética de angiospermas chilenas: Avances y proyecciones
PEDRO JARA-SEGUEL,JONATHAN URRUTIA
Revista chilena de historia natural , 2012,
Abstract: Cytogenetic data on Chilean angiosperms have been reported since at least eight decades ago; however, much of this information is disperse in diverse sources and is not readily available as a comprehensive document that allows having a general vision on advances and gaps in this matter. The goal of this paper is to summarize the advances and prospets on cytogenetic studies of the Chilean angiosperms based on compiled publications from 1929 to 2010. We found 78 publications supplied by four groups of Chilean researchers and some foreign specialists. Cytogenetic data have been reported for 139 Chilean angiosperm species (2.8 % of the total), which belong to 58 genera and 34 families. During 2001-2010 there was an increase in the number of publications, being available 40 reports including 95 additional species. Based on these data, we hope that such a trend can be maintained in the next decade if the current research groups and young specialists continue to be interested in the study of native plants. Los datos citogenéticos sobre angiospermas chilenas han sido reportados desde al menos ocho décadas atrás; sin embargo, mucha de esta información está dispersa en diversas fuentes y no está disponible como un documento completo que permita tener una visión general sobre los avances y vacíos en esta materia. El objetivo de este trabajo es resumir los avances y proyecciones sobre los estudios citogenéticos disponibles para angiospermas chilenas, basado en publicaciones recopiladas desde 1929 hasta el 2010. Nosotros encontramos 78 publicaciones aportadas por cuatro grupos de investigadores chilenos y por algunos especialistas extranjeros. Datos citogenéticos han sido reportados para 139 especies de angiospermas chilenas (2.8 % del total), las cuales pertenecen a 58 géneros y 34 familias. Durante los a os 2001-2010, existió un incremento en el número de publicaciones estando disponibles 40 reportes que incluyen 95 especies adicionales. Basados en estos datos, esperamos que esta tendencia pueda ser mantenida en la siguiente década si los actuales grupos de investigación y especialistas jóvenes siguen interesados en estudiar plantas nativas.
Effect of both protective and reducing agents in the synthesis of multicolor silver nanoparticles
Pedro Jose Rivero, Javier Goicoechea, Aitor Urrutia and Francisco Javier Arregui
Nanoscale Research Letters , 2013, DOI: 10.1186/1556-276X-8-101
Abstract: In this paper, the influence of variable molar ratios between reducing and loading agents (1:100, 1:50, 1:20, 1:10, 1:5, 1:2, 1:1, 2:1) and between protective and loading agents (0.3:1, 0.75:1, 1.5:1, 3:1, 7.5:1, 30:1, 75:1) in the synthesis of silver nanoparticles by chemical reduction has been evaluated to obtain multicolor nanoparticles with a high stability in time. The protective agent poly(acrylic acid, sodium salt) (PAA) and reducing agent dimethylaminoborane (DMAB) play a key role in the formation of the resultant color. Evolution of the optical absorption bands of the silver nanoparticles as a function of PAA and DMAB molar ratios made it possible to confirm the presence of silver nanoparticles or clusters with a specific shape. The results reveal that a wide range of colors (violet, blue, green, brown, yellow, red, orange), sizes (from nanometer to micrometer), and shapes (cubic, rod, triangle, hexagonal, spherical) can be perfectly tuned by means of a fine control of the PAA and DMAB molar concentrations.
An antibacterial coating based on a polymer/sol-gel hybrid matrix loaded with silver nanoparticles
Rivero Pedro,Urrutia Aitor,Goicoechea Javier,Zamarre?o Carlos
Nanoscale Research Letters , 2011,
Abstract: In this work a novel antibacterial surface composed of an organic-inorganic hybrid matrix of tetraorthosilicate and a polyelectrolyte is presented. A precursor solution of tetraethoxysilane (TEOS) and poly(acrylic acid sodium salt) (PAA) was prepared and subsequently thin films were fabricated by the dip-coating technique using glass slides as substrates. This hybrid matrix coating is further loaded with silver nanoparticles using an in situ synthesis route. The morphology and composition of the coatings have been studied using UV-VIS spectroscopy and atomic force microscopy (AFM). Energy dispersive X-ray (EDX) was also used to confirm the presence of the resulting silver nanoparticles within the thin films. Finally the coatings have been tested in bacterial cultures of genus Lactobacillus plantarum to observe their antibacterial properties. It has been experimentally demonstrated that these silver loaded organic-inorganic hybrid films have a very good antimicrobial behavior against this type of bacteria.
Frecuencia de infecciones de transmisión sexual y factores relacionados en Pweto, República Democrática del Congo, 2004
Luque Fernández,Miguel ángel; Bauernfeind,Ariane; Palma Urrutia,Pedro Pablo; Ruiz Pérez,Isabel;
Gaceta Sanitaria , 2008,
Abstract: objectives: to estimate the prevalence of genital ulcer and urethral discharge in pweto, democratic republic of congo, and to analyze the association between the estimated prevalence and age, marital status, profession, and number of sexual partners. methods: we performed a descriptive cross-sectional study through a survey conducted in may 2004 in a representative sample of 106 men in pweto aged between 15 and 65 years old, with a precision of 9.5%. questionnaire items about current or previous ulceration and urethral discharge where self-reported and referred to the previous year as of the date of the survey. to study the associations, crude and adjusted odds ratios (or) were calculated using multivariate logistic regression. results: the prevalence was 39.6% (95% confidence interval [ci], 30-49) for urethral discharge and 33% (95%ci, 24-42) for genital ulcer. soldiers were identified as a risk group independently of age, the number of sexual partners during the previous year, and marital status. the multivariate analysis showed an adjusted or of 3.25 (95%ci, 1.10-9.95) (p < 0.05) for the frequency of urethral discharge in soldiers compared with other professions. conclusions: the high prevalence of sexually transmitted infections in pweto and the associated factors identified prompted the initiation of a controlled condom donation program for soldiers. in conflict situations with a high prevalence of sexually transmitted infections and lack of health services, humanitarian aid organizations should implement prevention activities focused on risk groups.
UN MODELO DUAL PARA PORTAFOLIOS DE INVERSION.
EDUARDO ARTURO CRUZ TREJOS,JORGE ANDRéS URRUTIA MOSQUERA,PEDRO DANIEL MEDINA VARELA
Scientia Et Technica , 2011,
Abstract: El Objetivo básico financiero se fundamenta en crear valor para el inversionista, ya sea maximizar la rentabilidad de la empresa o minimizar la inversión requerida. Lo anterior manifiesta la necesidad de gestar herramientas de fácil manejo para cualquier interesado en invertir en activos financieros, que le permita manejar un conjunto de inversiones a través de modelos de optimización en forma sencilla. Este artículo presenta la construcción de un portafolio de renta fija maximizando la rentabilidad y su modelo dual financiero minimizar la inversión requerida.
On k-Convex Polygons
Oswin Aichholzer,Franz Aurenhammer,Erik D. Demaine,Ferran Hurtado,Pedro Ramos,Jorge Urrutia
Computer Science , 2010,
Abstract: We introduce a notion of $k$-convexity and explore polygons in the plane that have this property. Polygons which are \mbox{$k$-convex} can be triangulated with fast yet simple algorithms. However, recognizing them in general is a 3SUM-hard problem. We give a characterization of \mbox{$2$-convex} polygons, a particularly interesting class, and show how to recognize them in \mbox{$O(n \log n)$} time. A description of their shape is given as well, which leads to Erd\H{o}s-Szekeres type results regarding subconfigurations of their vertex sets. Finally, we introduce the concept of generalized geometric permutations, and show that their number can be exponential in the number of \mbox{$2$-convex} objects considered.
Relación entre el grado de contacto perro-propietario y la carga de helicobacterias en mucosa gástrica canina
Luzio Quiroga,Alvaro; Urrutia Cid,Pedro; Merino Mu?oz,Victoria; Tobar Villanueva,Juan; García Cancino,Apolinaria;
Revista Científica , 2009,
Abstract: helicobacter, gram negative bacterias are curved or helicoidal microorganisms, widely spread in the stomach of humans and several animals, found as normal microbiota or causing of gastrointestinal pathologies. the objective of the work consisted of determining the relation between the presence and loads of helicobacterias in canine, with the degree of contact with its positive owners proprietors to these bacteria using rapid urease test. a sample of 31 healthy dogs of the city of chillán, chile were used, from which gastric fungus biopsies were obtained by endoscopy. these biopsies were put under the rapid urease test. the owner of these canines were all positive for helicobacteria, determined by means of the same test. ninety sevent percent of the canine biopsies were positive for helicobacteria. thirty nine percent of the biopsies with the fastest positive reaction to the urease test belonged to canines with a high contact grade to their owners. the results suggestthat the high charges of helicobacteria found in canines could be because of the higher contact grade of these animals with their owner. it would be important then to determine in future studies, whether if these pets could be a reserve or a transmission source for people, or viceverse, and the bacterial species involved.
KRAB-containing zinc-finger repressor proteins
Raul Urrutia
Genome Biology , 2003, DOI: 10.1186/gb-2003-4-10-231
Abstract: Zinc-finger proteins containing the Krüppel-associated box (KRAB-containing proteins) were discovered in 1991 by Bellefroid et al. [1]. They make up approximately one third (290) of the 799 different zinc-finger proteins present in the human genome, and as a result, this group of proteins is the largest single family of transcriptional regulators in mammals. Many genes encoding KRAB-containing proteins are arranged in clusters, but others occur individually throughout the genome. The best characterized cluster is on 19q, containing 148 genes (51% of the family) within a region close to 19q13 [2]; other clusters are in centromeric and telomeric regions of other chromosomes. In particular, members of the family containing SCAN domains (see below) are clustered on 3p21-22, 6p21-22, 16p13.3, and 17p12-13. Non-clustered genes encoding KRAB-containing proteins are scattered over the other chromosomes, with about half on autosomes and half on sex chromosomes. Although the expression of genes of other clustered families, such as homeobox genes, is coregulated, it remains to be determined whether a comparable mechanism operates for genes encoding KRAB-containing proteins, and more studies are needed to show how chromosome organization influences the expression patterns of this family.As shown in Figure 1, KRAB-containing proteins are characterized by the presence of a DNA-binding domain made up of between 4 and over 30 zinc-finger motifs and a KRAB domain. The KRAB domain, located near the amino terminus of the protein, consists of one or both of the KRAB A box and the KRAB B box (see below). Other domains, such as the SCAN domain, are found in a small subset of members of the family [2,3] (Table 1). The two boxes of the KRAB domain are always encoded by individual exons separated by introns of variable sizes. This exon-intron composition allows the generation of different products by alternative splicing. In fact, zinc-finger proteins that contain only a KRAB A domain, for
Los eslabonamientos y la historia económica de Colombia
Urrutia,Miguel;
Desarrollo y Sociedad , 2008,
Abstract: the paper analyzes albert hirschman′s theory of linkages in economic development in his writings, and the possible influence of his colombia experience in the development of this idea. the theory is then applied to explain colombia's economic history in the nineteenth and twentieth century.
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