INFLUENCE OF AGE AND HEIGHT POSITION ON COLOMBIAN GUADUA ANGUSTIFOLIA BAMBOO MECHANICAL PROPERTIES

The age of bamboo is a key factor that affects its mechanical properties. Bamboo Guadua angustifolia kunt (Guadua a.k.) has been used as a construction material in America, but the influence of the age and height position of the culm on the mechanical properties has not been studied in detail. In this study, selected mechanical properties of Guadua a.k from 2 to 5 year old culms, located at different heights, were investigated using international standard test procedures (ISO 22157). Based on the experimental results, it was found that the top portion (sobrebasa) showed the maximum strength and modulus of elasticity compared to the other portions, since this portion of bamboo has higher density. More over, density of Guadua a.k. culm has more influence in modulus of rupture in bending, than in any of the other studied mechanical properties. Regardless of the culm height, it seems that the mature age of Guadua angustifolia kunt is reached between 3 and 4 years old, because the mechanical properties at those ages were the highest and remained almost constant, whereas the mechanical properties of the culms at the age of 5 were the lowest

Influence of age and height position on colombian Guadua angustifolia bamboo mechanical properties

The age of bamboo is a key factor that affects its mechanical properties. Bamboo Guadua angustifolia kunt (Guadua a.k.) has been used as a construction material in America, but the influence of the age and height position of the culm on the mechanical properties has not been studied in detail. In this study, selected mechanical properties of Guadua a.k from 2 to 5 year old culms, located at different heights, were investigated using international standard test procedures (ISO 22157). Based on the experimental results, it was found that the top portion (sobrebasa) showed the maximum strength and modulus of elasticity compared to the other portions, since this portion of bamboo has higher density. More over, density of Guadua a.k. culm has more influence in modulus of rupture in bending, than in any of the other studied mechanical properties. Regardless of the culm height, it seems that the mature age of Guadua angustifolia kunt is reached between 3 and 4 years old, because the mechanical properties at those ages were the highest and remained almost constant, whereas the mechanical properties of the culms at the age of 5 were the lowest

Gado crioulo colombiano Sanmartinero, sua conservação e contribuição sustentável para a produção de bovinos nos Orinoquia colombianos

This article highlights historical aspects of the origin of Colombian Creole cattle, with an emphasis on Sanmartinero (SM) cattle, which developed in the foothills and altillanura of the Colombian Orinoquia region, thanks to the work of natural selection and the zootechnical effort of the Jesuits, in the seventeenth century, with cattle introduced by the Spanish in the fifteenth century. Aspects related to its recent history are presented from the beginning of its conservation in Granja Iracá (San Martín, Meta) and its subsequent transfer to the Research Centers (CI) of the Colombian Agricultural Institute ICA, La Libertad, piedemonte llanero in Villavicencio (Meta) and Carimagua in the Colombian altillanura (Puerto Gaitán, Meta), centers that since 1994 have been in possession of the Colombian agricultural research corporation, AGROSAVIA. The main research results carried out in the CI La Libertad and related to all biological and economic aspects of the conservation, characterization and use of the breed are summarized. Similarly, results of the use of the breed in breeding systems (meat) and milk are presented in farms of pure and commercial breeders. Their qualities and productive skills are described as purebred and in crossbreeds – heterosis – with other races, especially with commercial Cebu C type Brahman. Of all the research experiences and positive results, especially of the adaptive characteristics – fertility, longevity, climate resistance, parasites and endemic diseases – and to their great combinatorial ability and to produce heterosis it is concluded that the SM is the best competitive and sustainable alternative to improve the production, profitability and quality of the final product, mainly meat, of the breeding and milk systems of the Colombian Orinoquia.Este artículo resalta aspectos históricos del origen de los ganados criollos colombianos, con énfasis en el bovino de raza Sanmartinero (SM), el cual se desarrolló en el piedemonte y altillanura de la región de la Orinoquia colombiana, gracias al trabajo de la selección natural y al esfuerzo zootécnico de los jesuitas, en el siglo XVII, con los bovinos introducidos por los españoles en el siglo XV. Se presentan aspectos relacionados con su historia reciente a partir del inicio de su conservación en la Granja Iracá (San Martín, Meta) y su posterior traslado a los Centros de Investigación (CI) del Instituto Colombiano Agropecuario ICA, La Libertad, piedemonte llanero en Villavicencio (Meta) y Carimagua en la altillanura colombiana (Puerto Gaitán, Meta), centros que desde el año 1994 han estado en poder de la Corporación colombiana de investigación agropecuaria, AGROSAVIA. Se resumen los principales resultados de investigación, llevados a cabo en el CI La Libertad y referentes a todos los aspectos biológicos y económicos de la conservación, caracterización y utilización de la raza. Igualmente, se presentan resultados de la utilización de la raza en sistemas de cría (carne) y leche en fincas de criadores puros y comerciales. Se describen sus cualidades y aptitudes productivas, como raza pura y en cruces – heterosis - con otras razas, especialmente con Cebú comercial tipo Brahman. De todas las experiencias de investigación y resultados positivos, especialmente de los caracteres adaptativos – fertilidad, longevidad, resistencia al clima, parásitos y enfermedades endémicas - y a su gran habilidad combinatoria y para producir heterosis se concluye que el SM es la mejor alternativa competitiva y sustentable para mejorar la producción, rentabilidad y calidad del producto final, principalmente carne, de los sistemas de cría y leche de la Orinoquia Colombiana.Este artigo destaca aspectos históricos da origem do gado crioulo colombiano, com ênfase no bovino da raça Sanmartinero (SM), desenvolvido no sopé e no sótão da região colombiana de Orinoquia, graças ao trabalho de seleção natural e ao esforço zootécnico dos jesuítas, no século XVII, com o gado introduzido pelos espanhóis no século XV. Aspectos relacionados à sua história recente são apresentados desde o início de sua conservação na Fazenda Iracá (San Martín, Meta) e sua subsequente transferência para os Centros de Pesquisa (CI) do Instituto Agrícola Colombiano ICA, La Libertad, no sopé das planícies em Villavicencio (Meta) e Carimagua no altillanura colombiano (Puerto Gaitán, Meta), centros que desde 1994 são mantidos pela Corporação Colombiana de Pesquisa Agrícola, AGROSAVIA. Os principais resultados da pesquisa são resumidos, realizados na CI La Libertad e referentes a todos os aspectos biológicos e econômicos da conservação, caracterização e uso da raça. Da mesma forma, são apresentados os resultados do uso da raça em sistemas de criação (carne) e leite em fazendas de criadores puros e comerciais. Suas qualidades e aptidões produtivas são descritas como uma raça pura e em cruzamentos - heterose - com outras raças, especialmente no comercial Brahman do tipo zebu. De todas as experiências de pesquisa e resultados positivos, especialmente as características adaptativas - fertilidade, longevidade, resistência ao clima, parasitas e doenças endêmicas - e sua grande capacidade combinatória e de produzir heterose, conclui-se que a EM é a melhor alternativa competitiva e sustentável melhorar a produção, a lucratividade e a qualidade do produto final, principalmente carne, proveniente dos sistemas agropecuário e de leite da Orinoquia colombiana

CLASH-VLT: A Highly Precise Strong Lensing Model of the Galaxy Cluster RXC J2248.7-4431 (Abell S1063) and Prospects for Cosmography

We perform a comprehensive study of the total mass distribution of the galaxy cluster RXCJ2248 ($z=0.348$) with a set of high-precision strong lensing models, which take advantage of extensive spectroscopic information on many multiply lensed systems. In the effort to understand and quantify inherent systematics in parametric strong lensing modelling, we explore a collection of 22 models where we use different samples of multiple image families, parametrizations of the mass distribution and cosmological parameters. As input information for the strong lensing models, we use the CLASH HST imaging data and spectroscopic follow-up observations, carried out with the VIMOS and MUSE spectrographs, to identify bona-fide multiple images. A total of 16 background sources, over the redshift range $1.0-6.1$, are multiply lensed into 47 images, 24 of which are spectroscopically confirmed and belong to 10 individual sources. The cluster total mass distribution and underlying cosmology in the models are optimized by matching the observed positions of the multiple images on the lens plane. We show that with a careful selection of a sample of spectroscopically confirmed multiple images, the best-fit model reproduces their observed positions with a rms of $0.3$ in a fixed flat $\Lambda$CDM cosmology, whereas the lack of spectroscopic information lead to biases in the values of the model parameters. Allowing cosmological parameters to vary together with the cluster parameters, we find (at $68\%$ confidence level) $\Omega_m=0.25^{+0.13}_{-0.16}$ and $w=-1.07^{+0.16}_{-0.42}$ for a flat $\Lambda$CDM model, and $\Omega_m=0.31^{+0.12}_{-0.13}$ and $\Omega_\Lambda=0.38^{+0.38}_{-0.27}$ for a universe with $w=-1$ and free curvature. Using toy models mimicking the overall configuration of RXCJ2248, we estimate the impact of the line of sight mass structure on the positional rms to be $0.3\pm 0.1$.(ABRIDGED)Comment: 23 pages, 13 figures, accepted for publication in A&

Corrigendum:Comprehensive Molecular Characterization of Escherichia coli Isolates from Urine Samples of Hospitalized Patients in Rio de Janeiro, Brazil (Frontiers in Microbiology, (2018), 9, (243), 10.3389/fmicb.2018.00243)

[This corrects the article DOI: 10.3389/fmicb.2018.00243.]

Riesgo sísmico, geotécnico y estructural. El caso de estudio de los edificios San Jerónimo de Yuste en Bogotá

San Jerónimo de Yuste buildings are located in Bogotá, on sloping ground, in the foothills of the city. These buildings were built between 2008 and 2011 by the company BIO Construcciones, as part of a broader development project promoted by the family compensation fund Compensar. During the months of May and June 2013 the slope suffered both vertical and horizontal displacements that visibly damaged two of the buildings, which were then evacuated. This paper presents the studies conducted by the Architecture and Engineering Schools at Universidad de los Andes, in order to determine the causes that led to movement, estimate the safety factor and propose interventions at the geotechnical and structural levels which would allow the recovery of the affected buildings.El conjunto residencial San Jerónimo de Yuste se encuentra ubicado en Bogotá, en un terreno inclinado en el pie de monte de los cerros orientales de la ciudad. Fue construido entre 2008 y 2011, como parte de un proyecto de urbanización promovido por la caja de compensación familiar Compensar. Durante mayo y junio de 2013 el terreno presentó desplazamientos tanto verticales como horizontales que generaron daños visibles en las estructuras y motivaron la evacuación de dos de las seis torres que conforman el conjunto. El presente trabajo presenta los resultados de la investigación que llevaron a cabo los grupos de investigación de las facultades de Arquitectura e Ingeniería de la Universidad de los Andes para determinar las causas que condujeron al evento de desplazamiento de la estructura debidas al movimiento del terreno, estimar el coeficiente de seguridad actual y proponer intervenciones geotécnicas y estructurales que permitan recuperar la edificación

Strong lensing models of eight CLASH clusters from extensive spectroscopy: accurate total mass reconstructions in the cores

We carry out a detailed strong lensing analysis of a sub-sample of eight galaxy clusters of the CLASH survey, in the redshift range of $z_{\rm cluster} = [0.23-0.59]$, using extensive spectroscopic information, primarily MUSE archival data complemented with CLASH-VLT redshift measurements. Different models are tested in each cluster depending on the complexity of its mass distribution and on the number of detected multiple images. Four clusters show more than five spectroscopically confirmed multiple image families. In this sample, we do not make use of families that are only photometrically identified, in order to reduce model degeneracies and systematics due to the potential misidentifications of some multiple images. We present spectroscopic confirmation of 27 multiply lensed sources, with no previous spectroscopic measurements, spanning over the redshift range of $z_{\rm src}=[0.7-6.1]$. Moreover, we confirm an average of $48$ galaxy members in the core of each cluster, thanks to the high efficiency and large field of view of MUSE. Despite having different properties (i.e., number of mass components, total mass, redshift, etc), the projected total mass and mass density profiles of all clusters have very similar shapes, when rescaled by independent measurements of $M_{200c}$ and $R_{200c}$. Specifically, we measure the mean value of the projected total mass of our cluster sample within 10 (20)% of $R_{200c}$ to be 0.13 (0.32) of $M_{200c}$, with a remarkably small scatter of 5 (6)%. Furthermore, the large number of high-z sources and the precise magnification maps derived in this work for four clusters add up to the sample of high-quality gravitational telescopes to be used to study the faint and distant Universe. The strong lensing models and the full redshift catalogues from MUSE are publicly available.Comment: 27 pages, 9 figures, 7 tables, updated to match the published version. Full redshift catalogue and lensing models are available at http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/632/A3

Évaluation de la quantité et la qualité des eaux de ruissellement pour les systèmes modulaires de toiture végétalisée extensive

Colloque avec actes et comité de lecture. Internationale.International audienc

I read it on reddit: Exploring the role of online communities in the 2016 US elections news cycle

Reddit has developed into a significant platform for political discussion among Millennials. In this exploratory study, we examine subscription trends on three political sub-forums on Reddit during the 2016 US presidential elections: /The_Donald, /SandersForPresident, and /HillaryClinton. As a theoretical framework, we draw from work on online communities’ group identity and cohesion. Concretely, we investigate how subscription dynamics relate to positive, negative and neutral news events occurring during the election cycle. We classify news events using a sentiment analysis of event-related news headlines. We observe that users who supported Sanders displayed no consolidation of support for Clinton after she won the Democratic Party’s presidential nomination. Secondly, we show that negative news events affected Sanders and Clintons subscription trends negatively, while showing no effect for Donald Trump. This gives empirical credence to Trump’s controversial claim that he could “stand in the middle of 5th Avenue and shoot somebody and not lose any voters”. We offer a number of explanations for the observed phenomena: the nature of the content of the three subreddits, their cultural dynamics, and changing dynamics of partisanship. We posit that the ‘death of expertise’ expresses itself on Reddit as a switch in persuasion tactics from a policy-based to an emotions-based approach, and that group members’ agreement on policy proved a weak marker for online communities’ group identity and cohesion. We also claim that strong partisanship coupled with weak party affiliation among Millennials contributed to the low levels of Democratic support consolidation after Clinton won the nomination