Evaluación de bloques de concreto, sustituyendo parcialmente la arena por polvo de madera, Chota.

Se analizaron y evaluaron las propiedades de los agregados y bloques de concreto no portantes sustituyendo parcialmente la arena por polvo de madera en porcentajes de: 0%. 2.5%, 5%, 10% y 15%, obteniendo resistencias a la compresión mayores a la resistencia mínima que es de 20 kg /cm2. El diseño de mezla se realizó con el método de módulo de finura en el laboratorio “GSE”. Se vio las ventajas y desventajas de los resultados obtenidos, llegando a la conclusión que con el 15% se obtuvo los bloques deseados, los cuales son el 13% más livianos y su elaboración es de menor costo y cumplen con la resistencia indicada en la Norma RNE E.070.ÍNDICE DE CONTENIDOS I. INTRODUCCIÓN………………………...………………………………………1 1.1. Planteamiento del problema…………………………………………………......1 1.2. Formulación del problema……………………………………………………..1 1.3. Justificación de la investigación………………………………………………..4 1.4. Delimitación de la investigación………………………………………………..7 1.5. Limitaciones……………………………………………………………………..7 1.6. Objetivos………………………………………………………………………...8 1.6.1. Objetivo general……………………………………………………………..8 1.6.2. Objetivos específicos………………………………………………………..8 II. MARCO TEÓRICO ……………………………………………………………..9 2.1. Antecedentes de la investigación ……………………………………………….9 2.1.1. Antecedentes Internacionales………………………………………………..9 2.1.2. Antecedentes Nacionales…………………………………………………….10 2.1.3. Antecedentes Regionales…………………………………………………….12 2.2. Marco teórico…………………………………………………………………..13 2.3. Definición de términos………………………………………………………...43 III. PLANTEAMIENTO DE LA HIPÓTESIS Y VARIABLES………………...44 3.1. Hipótesis………………………………………………………………………..44 3.1.1. General………………………………………………………………………44 3.1.2. Especifica……………………………………………………………………44 3.2. Variables……………………………………………………………………….44 3.2.1. Variable independiente………………………………………………………44 3.2.2. Variable dependiente………………………………………………………..44 3.3. Operacionalización de variables……………………………………………..45 IV. MARCO METODOLÓGICO………………………………………………….46 4.1. Ubicación geográfica del estudio……………………………………………...46 4.2. Unidad de análisis, población y muestra …………………………………….46 4.2.1. Población ……………………………………………………………………46 4.2.2. Muestra………………………………………………………………………46 4.2.3. Unidad de análisis …………………………………………………………...47 4.3. Tipo y descripción del diseño de investigación ………………………………47 4.3.1. Tipo de investigación………………………………………………………...47 4.3.2. Diseño de investigación …………………………………………………….48 4.3.3. Métodos de investigación……………………………………………………50 4.4. Técnicas e instrumentos de recolección de datos……………………………50 4.5. Técnicas para el procesamiento y análisis de información …………………52 4.6. Matriz de consistencia metodológica…………………………………………52 V. RESULTADOS Y DISCUSIONES…………………………………………...55 5.1. Origen de los materiales utilizados……………………………………………..55 5.2. Análisis, interpretación y discusión de resultados………………………………59 5.3. Costos………………………………………………………………………….115 5.4. Contrastación de hipótesis……………………………………………………..119 CONCLUSIONES……………………………………………………………………121 RECOMENDACIONES……………………………………………………………..123 REFERENCIAS BIBLIOGRAFICAS………………………………………………124 ANEXOS……………

Determinants of researchgate (rg) score for the top 100 of Latin American universities at webometrics

This paper has the purpose of establishing the variables that explain the behavior of ResearchGate for the Top100 Latin American universities positioned in Webometrics database for January 2017. For this purpose, a search was carried out to get information about postgraduate courses and professors at the institutional websites and social networks, obtaining documents registered in Google Scholar. For the data analysis, the econometric technique of ordinary least squares was applied, a cross-sectional study for the year 2017 was conducted, and the individuals studied were the first 100 Latin American universities, obtaining a coefficient of determination of 73.82%. The results show that the most significant variables are the number of programs, the number of teacher’s profiles registered in Google Scholar, the number of subscribers to the institutional YouTube channel, and the GDP per capita of the university origin country. Variables such as (i) number of undergraduate programs, (ii) number of scientific journals; (iii) number of documents found under the university domain; (iv) H-index of the 1st profile of researcher at the university; (vi) number of members of the institution; (v) SIR Scimago ranking of Higher Education Institutions; (vi) number of tweets published in the institutional account; (vii) number of followers in the Twitter institutional account; (vii) number of “likes” given to the institutional count, were not significantCorporación Universitaria Minuto de Dios, Fundación Universitaria Konrad Lorenz, Universidad Nacional Experimental Politécnica, Universidad Centroccidental “Lisandro Alvarado, Universidad de la Costa

Clinical chronobiology: a timely consideration in critical care medicine

A fundamental aspect of human physiology is its cyclical nature over a 24-h period, a feature conserved across most life on Earth. Organisms compartmentalise processes with respect to time in order to promote survival, in a manner that mirrors the rotation of the planet and accompanying diurnal cycles of light and darkness. The influence of circadian rhythms can no longer be overlooked in clinical settings; this review provides intensivists with an up-to-date understanding of the burgeoning field of chronobiology, and suggests ways to incorporate these concepts into daily practice to improve patient outcomes. We outline the function of molecular clocks in remote tissues, which adjust cellular and global physiological function according to the time of day, and the potential clinical advantages to keeping in time with them. We highlight the consequences of "chronopathology", when this harmony is lost, and the risk factors for this condition in critically ill patients. We introduce the concept of "chronofitness" as a new target in the treatment of critical illness: preserving the internal synchronisation of clocks in different tissues, as well as external synchronisation with the environment. We describe methods for monitoring circadian rhythms in a clinical setting, and how this technology may be used for identifying optimal time windows for interventions, or to alert the physician to a critical deterioration of circadian rhythmicity. We suggest a chronobiological approach to critical illness, involving multicomponent strategies to promote chronofitness (chronobundles), and further investment in the development of personalised, time-based treatment for critically ill patients

Basin-wide variation in tree hydraulic safety margins predicts the carbon balance of Amazon forests

Tropical forests face increasing climate risk1,2, yet our ability to predict their response to climate change is limited by poor understanding of their resistance to water stress. Although xylem embolism resistance thresholds (for example, Ψ50) and hydraulic safety margins (for example, HSM50) are important predictors of drought-induced mortality risk3–5, little is known about how these vary across Earth’s largest tropical forest. Here, we present a pan-Amazon, fully standardized hydraulic traits dataset and use it to assess regional variation in drought sensitivity and hydraulic trait ability to predict species distributions and long-term forest biomass accumulation. Parameters Ψ50 and HSM50 vary markedly across the Amazon and are related to average long-term rainfall characteristics. Both Ψ50 and HSM50 influence the biogeographical distribution of Amazon tree species. However, HSM50 was the only significant predictor of observed decadal-scale changes in forest biomass. Old-growth forests with wide HSM50 are gaining more biomass than are low HSM50 forests. We propose that this may be associated with a growth–mortality trade-off whereby trees in forests consisting of fast-growing species take greater hydraulic risks and face greater mortality risk. Moreover, in regions of more pronounced climatic change, we find evidence that forests are losing biomass, suggesting that species in these regions may be operating beyond their hydraulic limits. Continued climate change is likely to further reduce HSM50 in the Amazon6,7, with strong implications for the Amazon carbon sink

Effects of Cannabinoids on Caffeine Contractures in Slow and Fast Skeletal Muscle Fibers of the Frog

The effect of cannabinoids on caffeine contractures was investigated in slow and fast skeletal muscle fibers using isometric tension recording. In slow muscle fibers, WIN 55,212-2 (10 and 5 μM) caused a decrease in tension. These doses reduced maximum tension to 67.43 ± 8.07% (P = 0.02, n = 5) and 79.4 ± 14.11% (P = 0.007, n = 5) compared to control, respectively. Tension-time integral was reduced to 58.37 ± 7.17% and 75.10 ± 3.60% (P = 0.002, n = 5), respectively. Using the CB1 cannabinoid receptor agonist ACPA (1 μM) reduced the maximum tension of caffeine contractures by 68.70 ± 11.63% (P = 0.01, n = 5); tension-time integral was reduced by 66.82 ± 6.89% (P = 0.02, n = 5) compared to controls. When the CB1 receptor antagonist AM281 was coapplied with ACPA, it reversed the effect of ACPA on caffeine-evoked tension. In slow and fast muscle fibers incubated with the pertussis toxin, ACPA had no effect on tension evoked by caffeine. In fast muscle fibers, ACPA (1 μM) also decreased tension; the maximum tension was reduced by 56.48 ± 3.4% (P = 0.001, n = 4), and tension-time integral was reduced by 57.81 ± 2.6% (P = 0.006, n = 4). This ACPA effect was not statistically significant with respect to the reduction in tension in slow muscle fibers. Moreover, we detected the presence of mRNA for the cannabinoid CB1 receptor on fast and slow skeletal muscle fibers, which was significantly higher in fast compared to slow muscle fiber expression. In conclusion, our results suggest that in the slow and fast muscle fibers of the frog cannabinoids diminish caffeine-evoked tension through a receptor-mediated mechanism

Constraints on the Physical Properties of GW190814 through Simulations Based on DECam Follow-up Observations by the Dark Energy Survey

On 2019 August 14, the LIGO and Virgo Collaborations detected gravitational waves from a black hole and a 2.6 solar mass compact object, possibly the first neutron star–black hole merger. In search of an optical counterpart, the Dark Energy Survey (DES) obtained deep imaging of the entire 90% confidence level localization area with Blanco/DECam 0, 1, 2, 3, 6, and 16 nights after the merger. Objects with varying brightness were detected by the DES Pipeline, and we systematically reduced the candidate counterparts through catalog matching, light-curve properties, host-galaxy photometric redshifts, Southern Astrophysical Research spectroscopic follow-up observations, and machine-learning-based photometric classification. All candidates were rejected as counterparts to the merger. To quantify the sensitivity of our search, we applied our selection criteria to full light-curve simulations of supernovae and kilonovae as they would appear in the DECam observations. Because the source class of the merger was uncertain, we utilized an agnostic, three-component kilonova model based on tidally disrupted neutron star (NS) ejecta properties to quantify our detection efficiency of a counterpart if the merger included an NS. We find that, if a kilonova occurred during this merger, configurations where the ejected matter is greater than 0.07 solar masses, has lanthanide abundance less than 10−8.56, and has a velocity between 0.18c and 0.21c are disfavored at the 2σ level. Furthermore, we estimate that our background reduction methods are capable of associating gravitational wave signals with a detected electromagnetic counterpart at the 4σ level in 95% of future follow-up observations