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Imagen de apoyo de  Larger, more connected societies of ants have a higher prevalence of viruses = Las sociedades de hormigas más grandes y conectadas tienen una mayor prevalencia de virus

Larger, more connected societies of ants have a higher prevalence of viruses = Las sociedades de hormigas más grandes y conectadas tienen una mayor prevalencia de virus

Por: Anindita; Gray León Brahma | Fecha: 2021

Abstract: The benefits of cooperative living for foraging, nesting, defence and buffering envi- ronmental challenges lead animals with the most highly social lifestyles to dominate many ecosystems. However, living in larger, more highly connected groups should also increase the risks of pathogen exposure and transmission. While over long timescales selective responses could buffer the impacts of potential higher pathogen prevalence, similar processes are unlikely over short timescales. The red fire ant Solenopsis in- victa is ideal for measuring the effects of group size on pathogen prevalence because two types of society coexist in this species: smaller single-nest single-queen colonies that are highly aggressive to their neighbours and larger multiple-queen colonies that exchange resources with neighbouring nests. We compare the presence of viruses between these two colony types using metagenomic sequence classification of RNA- sequencing reads. We find that queens from multiple-queen colonies have 8.3-times higher viral load and 1.5-times higher viral diversity than queens from single-queen colonies. This finding characterizes a rarely considered cost of transitions to more highly social living. Furthermore, our results show that highly social invertebrates can harbour many viruses.
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Larger, more connected societies of ants have a higher prevalence of viruses = Las sociedades de hormigas más grandes y conectadas tienen una mayor prevalencia de virus

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Imagen de apoyo de  Effects of the Manufacturing Methods on the Mechanical Properties of a Medical-Grade Copolymer Poly(L-lactide-co-D,L-lactide) and Poly(L-lactide-co-ε-caprolactone) Blend

Effects of the Manufacturing Methods on the Mechanical Properties of a Medical-Grade Copolymer Poly(L-lactide-co-D,L-lactide) and Poly(L-lactide-co-ε-caprolactone) Blend

Por: Mariana; Civera Rodríguez Reinoso | Fecha: 2021

Abstract: Biocompatible and biodegradable polymers represent the future in the manufacturing of medical implantable solutions. As of today, these are generally manufactured with metallic components which cannot be naturally absorbed within the human body. This requires performing an additional surgical procedure to remove the remnants after complete rehabilitation or to leave the devices in situ indefinitely. Nevertheless, the biomaterials used for this purpose must satisfy well-defined mechanical requirements. These are difficult to ascertain at the design phase since they depend not only on their physicochemical properties but also on the specific manufacturing methods used for the target application. Therefore, this research was focused on establishing the effects of the manufacturing methods on both the mechanical properties and the thermal behavior of a medical-grade copolymer blend. Specifically, Injection and Compression Molding were considered. A Poly(L-lactide-co-D,L-lactide)/Poly(L-lactide-co-#-caprolactone) blend was considered for this investigation, with a ratio of 50/50 (w/w), aimed at the manufacturing of implantable devices for tendon repair. Interesting results were obtained.
Fuente: Biblioteca Virtual Banco de la República Formatos de contenido: Artículos
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Effects of the Manufacturing Methods on the Mechanical Properties of a Medical-Grade Copolymer Poly(L-lactide-co-D,L-lactide) and Poly(L-lactide-co-ε-caprolactone) Blend

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Imagen de apoyo de  Effects of Curing on Photosensitive Resins in SLA Additive Manufacturing

Effects of Curing on Photosensitive Resins in SLA Additive Manufacturing

Por: Carmela; Civera Riccio | Fecha: 2021

Abstract: Different mechanical properties characterise the materials of 3D printed components, depending on the specific additive manufacturing (AM) process, its parameters, and the posttreatment adopted. Specifically, stereolithography (SLA) uses a photopolymerisation technique that creates solid components through selective solidification. In this study, 72 specimens were 3D printed using 12 commercial-grade methacrylate resins and tested under uniaxial tensile loads. The resin specimens were evaluated before and after curing. The recommended cure temperature and time were followed for all materials. The stress-strain curves measured during the testing campaign were evaluated in terms of maximum tensile strength, Young’s modulus, ductility, resilience, and toughness. The results reveal that the curing process increases the material stiffness and resistance to tensile loads. However, it was found that the curing process generally reduces the plasticity of the resins, causing a more or less marked brittle behaviour. This represents a potential limitation to the use of SLA 3D printing for structural elements which require some plasticity to avoid dangerous sudden failures.
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Effects of Curing on Photosensitive Resins in SLA Additive Manufacturing

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Imagen de apoyo de  Recurring adaptive introgression of a supergene variant that determines social organization = Introgresión adaptativa recurrente de una variante de un supergen que determina la organización social

Recurring adaptive introgression of a supergene variant that determines social organization = Introgresión adaptativa recurrente de una variante de un supergen que determina la organización social

Por: Eckart; Pracana Stolle | Fecha: 2022

Abstract: Introgression has been proposed as an essential source of adaptive genetic variation. However, a key barrier to adaptive introgression is that recombination can break down combinations of alleles that underpin many traits. This barrier might be overcome in supergene regions, where suppressed recombination leads to joint inheritance across many loci. Here, we study the evolution of a large supergene region that determines a major social and ecological trait in Solenopsis fire ants: whether colonies have one queen or multiple queens. Using coalescent-based phylogenies built from the genomes of 365 haploid fire ant males, we show that the supergene variant responsible for multiple-queen colonies evolved in one species and repeatedly spread to other species through introgressive hybridization. This finding highlights how supergene architecture can enable a complex adaptive phenotype to recurrently permeate species boundaries.
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Recurring adaptive introgression of a supergene variant that determines social organization = Introgresión adaptativa recurrente de una variante de un supergen que determina la organización social

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Imagen de apoyo de  Impact of dimensionality on nowcasting seasonal influenza with environmental factors

Impact of dimensionality on nowcasting seasonal influenza with environmental factors

Por: Stefany Brigetty; Miliou Guarnizo Peralta | Fecha: Ca. 2020

Abstract: Seasonal influenza is an infectious disease of multi-causal etiology and a major cause of mortality worldwide that has been associated with environmental factors. In the attempt to model and predict future outbreaks of seasonal influenza with multiple environmental factors, we face the challenge of increased dimensionality that makes the models more complex and unstable. In this paper, we propose a nowcasting and forecasting framework that compares the theoretical approaches of Single Environmental Factor and Multiple Environmental Factors. We introduce seven solutions to minimize the weaknesses associated with the increased dimensionality when predicting seasonal influenza activity levels using multiple environmental factors as external proxies. Our work provides evidence that using dimensionality reduction techniques as a strategy to combine multiple datasets improves seasonal influenza forecasting without the penalization of increased dimensionality.
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Impact of dimensionality on nowcasting seasonal influenza with environmental factors

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Imagen de apoyo de  Population prevalence and trends of oral clefts in Colombia: analysis by departments

Population prevalence and trends of oral clefts in Colombia: analysis by departments

Por: Herney Alonso; Guarnizo Peralta Rengifo Reina | Fecha: 2021

Abstract: Objective: Determine the population prevalence and trends of cleft lip and / or palate (CL/P) by department for Colombia in the period 2009 - 2015. Methods: Prevalence study based on Individual Registry of Health Services in general population from 2009 to 2015. All people diagnosed with CL/P were included for all ages, type of diagnosis and any type of health services in the mentioned period. The prevalence rate was calculated by period and point for each year, for each department and according to the type of cleft. Stationarity on time series was evaluated using (Dickey-Fuller) and (Phillips-Perron), the trends and prevalence ratios were calculated using Poisson regression. Results: 15,225 people with CL/P were identified, where 53.3% were men. The national period prevalence of CL/P is 3.37 per 10 000 (IC95%: 3.3-3.4) with upward trend (PR = 1.34 95% CI: 1.0 - 1.8 p = 0.05) and non-stationary behavior. The national period prevalence of CL is 0.93 per 10 000, CP 1.17 per 10 000 and CLP 1.26 per 10 000, where CLP is sub classify into CLPu (0.83 per 10 000), and CLPb (0.43 per 10 000). At the departmental level, the highest CL/P prevalence is Guaviare (11.2 95% CI: 8.6 – 14.2), followed by Guainía (8.4 95% CI:5.4 – 12.2) and the lowest Quindío (0.49 95% CI: 0.3 – 0.7) Conclusions: In Colombia, the national period prevalence of CL/P is 3.37 per 10 000 with upward trend at national level indicates an increase on prevalence from 2009 to 2015.
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Population prevalence and trends of oral clefts in Colombia: analysis by departments

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Imagen de apoyo de  Analysis of the Prevalence and Incidence of Cleft Lip and Palate in Colombia

Analysis of the Prevalence and Incidence of Cleft Lip and Palate in Colombia

Por: Herney Alonso; Guarnizo Peralta Rengifo Reina | Fecha: 2020

Abstract: Objective: To analyze the population prevalence and birth prevalence of oral clefts in Colombia from 2009 to 2017. Methods: A cross-sectional study using information from the National Administrative Records of Colombia. The data came from 2 types of administrative records (Surveillance System and the Individual Registry of Service Provision) and the oral health national survey. Population prevalence and birth prevalence by type of cleft lip and/or cleft (CL/P) ratios were calculated using Poisson distribution for count data and to assess stationary tests on time series (Dickey-Fuller) and (Phillips-Perron) was used. Results: Population prevalence in Colombia was 3.27 per 10 000 inhabitants (95% confidence interval [CI], 3.21-3.32) and birth prevalence was 6.0 per 10 000 live births (95% CI, 5.67-6.35). Bogot´a have the highest population prevalence with CL/P. In the analysis of trends for the prevalence proportion by type of clefts in newborn babies with cleft, it was observed that the highest proportion was for babies with CLP. Cleft lip (CL) has increased from 17.4% in 2014 to 34.2% in 2017, cleft palate (CP) has decreased from 32.9% to 20.2%; and CLP changed from 49.6% to 45.5% in the same period. Conclusions: The population prevalence was 3.27 per 10 000 inhabitants. Births prevalence was 6.0 per 10 000 live births, and Orinoquia and Amazonia have higher rates than the national average. The administrative registers are adequate systems to know the behavior of oral clefts. The CL/P had a nonstationary trend during the period 2014 to 2017.
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Analysis of the Prevalence and Incidence of Cleft Lip and Palate in Colombia

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Imagen de apoyo de  Mechanical behaviour of bamboo at elevated temperatures – Experimental studies

Mechanical behaviour of bamboo at elevated temperatures – Experimental studies

Por: Mateo; Maluk Gutiérrez González | Fecha: 2020

Abstract: The growing demand for sustainable load-bearing materials drives the need for understanding the various design considerations these pose within the modern built environment. Engineered bamboo is a material with outstanding physical and mechanical properties, in addition to producing a minimum carbon footprint. However, extensive research is needed before engineered bamboo can be used with the confidence conferred to other more conventional building construction materials. When aiming for higher and larger bamboo-based structures, loadbearing behaviour during and after fire becomes a key consideration. This paper describes the outcomes of a comprehensive study conducted to understand the mechanical behaviour of bamboo (Phyllostachys pubescens species) at elevated temperatures; more specifically investigating the reduction of compressive and tensile strength, as well as the Modulus of Elasticity (MoE) up to 250 °C. Findings from this work show that at 200 °C, bamboo retains 20%, 42% and 70% of the compressive strength, tensile strength and modulus of elasticity at ambient, respectively. The results presented herein, which provide thorough understanding of strength and elasticity reduction at elevated temperatures, enable the development of stress-strain constitutive models that will constitute the basis for designing fire-safe bamboo structures.
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Mechanical behaviour of bamboo at elevated temperatures – Experimental studies

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Imagen de apoyo de  Educación e igualdad de oportunidades en las comunidades indígenas de Colombia

Educación e igualdad de oportunidades en las comunidades indígenas de Colombia

Por: Edda Patricia Izquierdo López | Fecha: 2021

Resumen: El derecho fundamental de las niñas y niños a la educación es más complejo de garantizar para las comunidades indígenas debido a que requiere lograr que las y los estudiantes accedan a una educación de calidad similar a la que reciben sus pares que les permita obtener las habilidades relevantes para competir en el mercado laboral e involucrarse en los desafíos de desarrollo económico y social que deben enfrentar sus propias comunidades; y, adicionalmente, que la educación impartida contribuya a preservar la existencia y forma de vida de la comunidad, que resalte el conocimiento tradicional y las prácticas culturales. Este documento, reseña la aproximación de Colombia a la provisión de educación para las comunidades indígenas -etnoeducación- a partir de una revisión normativa y el uso de datos administrativos del sector educación. Se encuentra que los docentes vinculados en concertación con las autoridades indígenas -etnoeducadores tienen menores salarios, formación académica y experiencia que el resto de docentes-. Adicionalmente, los estudiantes vinculados a establecimientos donde al menos 10% de los docentes son etnoeducadores, tienen peores resultados en el puntaje global, de lectura crítica y de matemáticas en las pruebas Saber 11. No obstante, una mayor proporción de educadores en las ETC y municipios parece tener un efecto positivo en la cobertura y disminuir la deserción.
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Educación e igualdad de oportunidades en las comunidades indígenas de Colombia

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Quitones (Mollusca: Polyplacophora) del mar Caribe colombiano

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