2,658 research outputs found
Nitrate and Inhibition of Ruminal Methanogenesis : Microbial Ecology, Obstacles, and Opportunities for Lowering Methane Emissions from Ruminant Livestock
Acknowledgments CY was supported by a scholarship from the China Scholarship Council. IC was supported by the SRUC International Engagement Strategy Fund. The nitrate project was funded by EBLEX, a Division of the Agriculture and Horticulture Development Board. RINH and SRUC are funded by the Rural and Environment Science and Analytical Services Division (RESAS) of the Scottish Government.Peer reviewedPublisher PD
The role of intermediaries in the synchronization of pulse-coupled oscillators
The role of intermediaries in the synchronization of small groups of light
controlled oscillators (LCO) is addressed. A single LCO is a two-time-scale
phase oscillator. When pulse-coupling two LCOs, the synchronization time
decreases monotonously as the coupling strength increases, independent of the
initial conditions and frequency detuning. In this work we study numerically
the effects that a third LCO induces to the collective behavior of the system.
We analyze the new system by dealing with directed heterogeneous couplings
among the units. We report a novel and robust phenomenon, absent when coupling
two LCOs, which consists of a discontinuous relationship between the
synchronization time and coupling strength or initial conditions. The mechanism
responsible for the appearance of such discontinuities is discussed.Comment: 11 pages, 8 figure
Effects of Composite Rheology on Plate-Like Behavior in Global-Scale Mantle Convection
Earth's upper mantle rheology controls lithosphere-asthenosphere coupling and thus surface tectonics. Rock deformation experiments and seismic anisotropy measurements indicate that composite rheology (co-existing diffusion and dislocation creep) occurs in the Earth's uppermost mantle, potentially affecting convection and surface tectonics. Here, we investigate how the spatio-temporal distribution of dislocation creep in an otherwise diffusion-creep-controlled mantle impacts the planform of convection and the planetary tectonic regime as a function of the lithospheric yield strength in numerical models of mantle convection self-generating plate-like tectonics. The low upper-mantle viscosities caused by zones of substantial dislocation creep produce contrasting effects on surface dynamics. For strong lithosphere (yield strength > 35 MPa), the large lithosphere-asthenosphere viscosity contrasts promote stagnant-lid convection. In contrast, the increase of upper mantle convective vigor enhances plate mobility for lithospheric strength <35 MPa. For the here-used model assumptions, composite rheology does not facilitate the onset of plate-like behavior at large lithospheric strength
Effect of preparation conditions on the polymorphism and transport properties of lanthanum molybdates
In this work, La6MoO12-based compounds were investigated as part of a new family of materials very competitive as hydrogen separation membranes [1,2].
La5.4MoO11.1 was synthesized by the freeze-drying precursor method and the calcination conditions were optimized in order to obtain single phases. Several cooling rates were applied and different polymorphs were obtained: a simple cubic fluorite symmetry (Fm-3m) for the sample cooled by quenching, and two different rhombohedral (R-3) space groups for the samples cooled at 50 ºC•min-1 and 0.5 ºC•min-1 (see Figure below). For the quenched sample, the Rietveld refinement was satisfactory in a Fm-3m space group. For the other two compositions no structural model was available and were indexed in a R-3 space group, however some small reflections were not given any intensity by the model used. Transmission electron microscopy confirmed the presence of superstructures for those samples. All ceramic materials were obtained with relative densities close to 100% after sintering at 1500 ºC. Stability studies demonstrated that all three polymorphs were stable in oxidizing and reducing conditions at 800 ºC for 48 hours.
The three samples present a significant proton contribution to the conductivity at temperatures lower than 800 ºC. These results were confirmed by thermogravimetric analysis. The highest conductivity values were observed for the samples prepared by quenching. The three polymorphs display a small p-type electronic contribution to the overall conductivity in oxidizing conditions and n-type electronic one in very reducing conditions, much more significant for the samples cooled by quenching and at 50 ºC•min-1.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
NIRS potential use for the determination of natural resources quality from dehesa (acorn and grass) in Montanera system for Iberian pigs.
NIRS technology has been used as an alternative to conventional methods to determinate the content of nutrients of acorns and grass from dehesa ecosystem. Dry matter (DM), crude fat (CF), crude protein (CP), starch, total phenolic compounds (TP), α-tocopherol, γ-tocopherol, fatty acids, neutral detergent fiber (NDF), total antioxidant activity (TAA) and total energy (TE) were determined by conventional methods for later development of NIRS predictive equations. The NIR spectrum of each sample was collected and for all studied parameters, a predictive model was obtained and external validated. Good prediction equations were obtained for moisture, crude fat, crude protein, total energy and γ-tocopherol in acorns samples, with high coefficients of correlation (1-VR) and low standard error of prediction (SEP) (1-VR=0.81, SEP=2.62; 1-VR=0.92, SEP=0.54; 1-VR=0.86, SEP=0.47; 1-VR=0.84, SEP=0.2; 1-VR=0.88, SEP=5.4, respectively) and crude protein, NDF, α-tocopherol and linolenic acid content in grass samples (1-VR=0.9, SEP=1.99; 1-VR=0.87, SEP=4.13; 1-VR=0.76, SEP=10.9; 1-VR=0.82, SEP=0.6, respectively). Therefore, these prediction models could be used to determinate the nutritional composition of Montanera natural resources
Evaluación de los Riesgos por Iluminación en los Puestos de Trabajo de Oficinas PDVSA a través de un Programa de Computación | Risk Assessment for Lighting in the Office Jobs PDVSA through a Computer Program
Se evalua el riesgo por las condiciones de iluminación en puestos de trabajo ubicados en oficinas de las instalaciones de Petróleos de Venezuela S.A. (PDVSA), específicamente en el Edificio de “La Campiña” (Caracas) y el Edificio (Maturín), además de calcular y rediseñar estos mediante la utilización de un software diseñado para tal fin. Se trata de una investigación de campo que permitió recoger los datos mediante luxometrías que serealizaron en los puestos de trabajo siguiendo los lineamientos dictados por la norma de la Comisión Venezolana de Normas Industriales (COVENIN) 2249-93 “Iluminancias en tareas y áreas de trabajo”, en el periodo 2006- 2007. Se encontró que el 69,65% de los puestos de trabajo no cumplen con la norma COVENIN 2249-93, por lo cual se hizo necesario la evaluación y el rediseño de la iluminación de los puestos de trabajo de las oficinas mencionadas, para optimizar las condiciones de los puestos de trabajo y cumplir de esta manera a cabalidad con las normas tanto nacionales como internacionales de iluminación en puestos de trabajo. Palabras clave: Iluminación, riesgo por iluminación, evaluación, rediseño. ABST RACT This risk for lighting conditions at workstations in offices of installations of Petroleos de Venezuela SA (PDVSA), specifically in the Building "La Campiña " (Caracas) and the Building (Maturin), were evaluated, and calculations to redesign these conditions were performed using a software designed for that purpose. This is a field research, which allowed the collection of data using luxometries in the workplace according to the norm of the Venezuelan Industrial Standards Committee (COVENIN) 2249-93 "Illuminance on tasks and work areas" in the period 2006-2007. It was found that 69.65% of the workstations did not meet the norm COVENIN 2249-93, so it was necessary to evaluate and redesign the lighting of the workstations in these locations, in order to optimize the working conditions fully comply with the national and international standards on lighting in workstations. Key words: Lighting, risk for lighting, evaluation, redesign
Thermophysical Characterization of Sorption TCM
AbstractThermochemical materials (TCM) are proposed for thermal energy storage as one of the future options to achieve lower energy consumption in buildings and other industrial applications, as well as to store energy from solar energy. In this study, the thermophysical properties of two TCM, CaCl2 and zeolite, are determined with TGA and DSC and samples are cycled 4 times with TGA. Results show that the material with the highest energy density is the salt, CaCl2. Moreover, both materials under study present noble cyclability
Use of E-beam radiation to eliminate Listeria monocytogenes from surface mould cheese
Camembert and Brie soft cheese varieties were subjected to E-beam irradiation as a sanitation treatment. The effects of treatments on microbiota and selected physicochemical properties were also studied. The absorbed doses required to meet the food safety objective (FSO) according to EU and USDA criteria for Listeria monocytogenes were 1.27 and 2.59 kGy, respectively. The bacterial load, mainly lactic acid bacteria, was reduced by the treatment but injured cells were recovered during storage at 14°C. The radiation treatment gave rise to negligible changes in the pH and water activity at doses required to achieve microbial safety. [Int Microbiol 2015; 18(1):33-40]Keywords: Listeria monocytogenes · food safety objective (FSO) · soft mould-ripened cheeses · E-beam radiatio
Small-worldness favours network inference in synthetic neural networks
R.A.G. and N.R. acknowledge Comisión Sectorial de Investigación Científica (CSIC) research grant 97/2016 (ini_2015_nomina_m2). All authors acknowledge CSIC group grant “CSIC2018 - FID13 - grupo ID 722”.Peer reviewedPublisher PD
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