537 research outputs found
Changes in nutrient balance, methane emissions, physiologic biomarkers, and production performance in goats fed different forage-to-concentrate ratios during lactation
[EN] The objective was to determine the effect forage-to-concentrate (F:C) ratio and stage of lactation on methane emissions, digestibility, nutrient balance, lactation performance, and metabolic responses in lactating goats. Twenty Murciano-Granadina dairy goats were used in an experiment divided into 3 periods: early (30 d), mid (100 d), and late (170 d) lactation. All goats were fed a diet with 35:65 F:C (FCL) during early-lactation. Then, 1 group (n = 10 goats) remained on FCL through mid- and late-lactation while the other group (n = 10 goats) was fed a diet with 50:50 F:C at mid-lactation (FCM) and 65:35 (FCH) at late lactation. A greater proportion of concentrate in the diet was associated with greater overall intake and digestibility (P < 0.05). Energy balance was negative in early-lactation (-77 kJ/kg of BW0.75, on average) and positive for FCL at mid- and late-lactation (13 and 35 kJ/kg of BW0.75, respectively). Goats fed FCM and FCH maintained negative energy balance throughout lactation. Plasma concentrations of non-esterified fatty acids at mid-lactation were greater for FCM than FCL (680 mEq/L), and at late-lactation concentrations were greater for FCH and FCL (856 mEq/L). A similar response was detected for plasma beta-hydroxybutyrate. Methane emission was greater (P < 0.05) for FCM than FCH (1.7 g CH4/d). This study demonstrated that differences in F:C across stages of lactation lead to distinct metabolic responses at the level of the rumen and tissues.This study was supported by LIFE Project, European Commission (ref. LIFE2016/CCM/ES/000088 LOW CARBON FEED).Fernández Martínez, CJ.; Hernández, A.; Gomis-Tena Dolz, J.; Loor, JJ. (2021). Changes in nutrient balance, methane emissions, physiologic biomarkers, and production performance in goats fed different forage-to-concentrate ratios during lactation. Journal of Animal Science. 99(7):1-13. https://doi.org/10.1093/jas/skab114S11399
Structural, mechanical and electronic properties of two-dimensional structure of III-arsenide (1 1 1) binary compounds: An ab-initio study
Structural, mechanical and electronic properties of two-dimensional single-layer hexagonal structures in the (1 1 1) crystal plane of IIIAs-ZnS systems (III = B, Ga and In) are studied by first-principles calculations based on density functional theory (DFT). Elastic and phonon dispersion relation display that 2D h-IIIAs systems (III = B, Ga and In) are both mechanical and dynamically stable. Electronic structures analysis show that the semiconducting nature of the 3D-IIIAs compounds is retained by their 2D single layer counterpart. Furthermore, density of states reveals the influence of σ and π bonding in the most stable geometry (planar or buckled) for 2D h-IIIAs systems. Calculations of elastic constants show that the Young's modulus, bulk modulus and shear modulus decrease for 2D h-IIIAs binary compounds as we move down on the group of elements of the periodic table. In addition, as the bond length between the neighboring cation-anion atoms increases, the 2D h-IIIAs binary compounds display less stiffness and more plasticity. Our findings can be used to understand the contribution of the σ and π bonding in the most stable geometry (planar o buckled) for 2D h-IIIAs systems. Structural and electronic properties of h-IIIAs systems as a function of the number of layers have been also studied. It is shown that h-BAs keeps its planar geometry while both h-GAs and h-InAs retained their buckled ones obtained by their single layers. Bilayer h-IIIAs present the same bandgap nature of their counterpart in 3D. As the number of layers increase from 2 to 4, the bandgap width for layered h-IIIAs decreases until they become semimetal or metal. Interestingly, these results are different to those found for layered h-GaN. The results presented in this study for single and few-layer h-IIIAs structures could give some physical insights for further theoretical and experimental studies of 2D h-IIIV-like systems
Modelos de pronósticos para incendios forestales en la provincia de Córdoba
En este artículo describimos el proyecto denominado Modelos de pronósticos para la detección de incendios forestales. Se describen los diferentes componentes que se encuentran operativos hasta el momento, sus objetivos y utilidades en lo que atañe a la gestión de incendios forestales.
Este proyecto tiene como objetivo principal elaborar un modelo que permita pronosticar la ocurrencia de incendios forestales en la Provincia de Córdoba, especialmente en las sierras de Córdoba y la región del Parque Chaqueño de la provincia.
Es parte de un desarrollo que involucra desde la recolección de la información meteorológica, su procesamiento, análisis, hasta su visualización.Eje: Agentes y sistemas inteligentes.Red de Universidades con Carreras en Informátic
Estrategias marinas: Evaluación inicial, buen estado ambiental y objetivos ambientales
El documento marco de las estrategias marinas es el marco general introductorio de los documentos que constituyen las primeras fases de las cinco estrategias marinas españolas. En el año 2012 el entonces Ministerio de Agricultura, Alimentación y Medio Ambiente preparó para cada una de las cinco demarcaciones marinas de España un documento de evaluación inicial, definición de buen estado ambiental y establecimiento de objetivos ambientales, que son las primeras fases en la elaboración de las estrategias marinas. A pesar de las particularidades de cada una de las demarcaciones marinas, existen elementos comunes a las estrategias marinas, que se han recogido en este documento marco.Versión del edito
Subsistemas para análisis de textos
En este artículo se presenta el proyecto de investigación denominado Desarrollo de Sistemas de Análisis de Texto. Este proyecto se centra en el estudio, análisis y procesamiento de información textual y en el desarrollo de herramientas software que permitan agilizar y facilitar su exploración e inferencia de información. Se presenta desde un enfoque de sistemas y subsistemas, las partes principales proyecto y las herramientas que se están desarrollando para abordar el procesamiento de textos. Las líneas de investigación en la que se encuadra el proyecto es dentro de las áreas de lingüística computacional y de aprendizaje automático, para atacar problemas con orígenes de texto con y sin estructura definida.Eje: Agentes y sistemas inteligentes.Red de Universidades con Carreras en Informátic
Balancing porosity and mechanical properties of titanium samples to favor cellular growth against bacteria
Two main problems limit the success of titanium implants: bacterial infection, which restricts their osseointegration capacity; and the stiffness mismatch between the implant and the host cortical bone, which promotes bone resorption and risk of fracture. Porosity incorporation may reduce this difference in stiffness but compromise biomechanical behavior. In this work, the relationship between the microstructure (content, size, and shape of pores) and the antibacterial and cellular behavior of samples fabricated by the space-holder technique (50 vol % NH4HCO3 and three ranges of particle sizes) is established. Results are discussed in terms of the best biomechanical properties and biofunctional activity balance (cell biocompatibility and antibacterial behavior). All substrates achieved suitable cell biocompatibility of premioblast and osteoblast in adhesion and proliferation processes. It is worth to highlighting that samples fabricated with the 100–200 μm space-holder present better mechanical behavior—in terms of stiffness, microhardness, and yield strength—which make them a very suitable material to replace cortical bone tissues. Those results exposed the relationship between the surface properties and the race of bacteria and mammalian cells for the surface with the aim to promote cellular growth over bacteria.University of Seville (Spain) VI Plan Propio de Investigación y Transferencia—US 2018, I.3A
Assessment of natural ventilation strategy to decrease the risk of COVID 19 infection at a rural elementary school
Natural ventilation in low-budget elementary schools is the main focus to ensure the health and comfort of its occupants, specifically when looking at the global pandemic related to SARS-COV-2. This paper presents an experimental and novel study of natural ventilation in a public elementary school (Los Zumacales), with a particularly low economic budget. The study was carried out during the winter months of the Covid 19 pandemic. The school is located in the rural area of Castilla y León (North-Western Spain) far from high traffic roads. In this study, a methodology of measuring CO2 concentration was applied in nine classrooms in a school. The experimental study shows the level of natural ventilation in each classroom, expressed in Air Changes per Hour (ACH), using the Decay CO2 concentration method. The method is proven by comparing the experimental values of the obtained ACH with those determined by the most powerful methods to achieve appropriate ventilation levels. Thus, ensuring health protection protocol in rural schools, against the COVID 19 pandemic. Harvard guide and Spanish regulations (RITE), two widely recognized methods have been used together with the experimentally obtained standard by Rey et al. Only one classroom showed a value lower than 3 indicating poor ventilation. In this study, the degree of thermal comfort in the nine classrooms were also analyzed according to the EN15251 standard. An average indoor temperature of approximately 19 °C was obtained, and the relative humidity was stable and correct according to Spanish regulations. In addition, the risk of infection in each classroom was estimated following the international method recommended by the federation of European Heating, Ventilation, and Air Conditioning Associations (REHVA). The probability of infection in all the cases studied was less than 14%.Funding for open access charge: Universidad de Málaga/CBU
Structural, electronic and magnetic properties of Ti-doped polar and nonpolar GaN surfaces
Based on density functional theory, first-principles calculations were performed in order to study the titanium incorporation on polar and nonpolar GaN surfaces. The formation energy calculations indicate that Ti impurity atoms prefer to incorporate in surface layers (first and second) of GaN. It is also concluded that the incorporation of Ti atoms in Ga-substitutional sites are more energetically favorable compared with N-substitutional or interstitial sites on the polar and nonpolar GaN surfaces. For Ti-rich growth conditions, formation energy calculations show the formation of TixN layers on the a and c GaN surfaces, which corroborates recent experimental observations. Results also display that the 3d-Ti states are the responsible for the metallization of the surface on the c and m planes, forming an intermetallic alloy (TixN), which could be used as low-resistance ohmic contacts for GaN. In addition, the magnetic properties with Ti doping show magnetization of about 1.0 μB/Ti atom for the nonpolar GaN surfaces
Light with a self-torque: extreme-ultraviolet beams with time-varying orbital angular momentum
Twisted light fields carrying orbital angular momentum (OAM) provide powerful
capabilities for applications in optical communications, microscopy, quantum
optics and microparticle rotation. Here we introduce and experimentally
validate a new class of light beams, whose unique property is associated with a
temporal OAM variation along a pulse: the self-torque of light. Self-torque is
a phenomenon that can arise from matter-field interactions in electrodynamics
and general relativity, but to date, there has been no optical analog. In
particular, the self-torque of light is an inherent property, which is
distinguished from the mechanical torque exerted by OAM beams when interacting
with physical systems. We demonstrate that self-torqued beams in the
extreme-ultraviolet (EUV) naturally arise as a necessary consequence of angular
momentum conservation in non-perturbative high-order harmonic generation when
driven by time-delayed pulses with different OAM. In addition, the
time-dependent OAM naturally induces an azimuthal frequency chirp, which
provides a signature for monitoring the self-torque of high-harmonic EUV beams.
Such self-torqued EUV beams can serve as unique tools for imaging magnetic and
topological excitations, for launching selective excitation of quantum matter,
and for manipulating molecules and nanostructures on unprecedented time and
length scales.Comment: 24 pages, 4 figure
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