1,539 research outputs found
Competencia digital y redes personales de aprendizaje de estudiantes en educación obligatoria
Las lecciones de los maestros como recurso para la docencia en el grado de arquitectura
[Resumen] Dentro de la especificidad del aprendizaje de la arquitectura, las figuras de los maestros del Movimiento Moderno juegan un papel fundamental. Sin haberse pretendido como textos docentes o enseñanzas regladas, sus escritos y sobretodo, sus propuestas teóricas o materializadas se convierten en lecciones esenciales para la docencia en arquitectura, tanto en las materias de proyectos como en las de composición arquitectónica, desde el primer curso del grado en arquitectura
Short communication. In vitro oocyte maturation and fertilization rates in the Spanish Lidia bovine breed
The Lidia bovine breed is the most successful cattle breed on the Iberian Peninsula, also considered a hallmark of
Spanish tradition and image around the world. The aims of the study were to characterize the oocyte recovery rates
and to evaluate the effect of two standard in vitro maturation protocols on oocyte maturation (cumulus expansion and
nuclear maturation) and fertilization rates after in vitro fertilization in this breed. For this purpose, 261 ovaries from
Lidia cows were processed obtaining 1,125 viable cumulus oocyte complexes (COCs). The oocyte recovery rate obtained
(4.31 viable COCs per ovary) was lower than those described previously in other studied breeds. Maturation rates were
evaluated in two different oocyte maturation media with (M1) and without (M2) hormonal supplementation. The
percentage of COCs with expanded cumulus cells was significantly lower in M1 (74.35%) compared with M2 (82.25%).
Metaphase II (MII) rates (67.75% in M1 and 73.18% in M2) were similar to previous studies in different cattle
populations. M2 significantly improved the percentage of COCs with their cumulus cells expanded (p < 0.01) and
nuclear maturation rates (p < 0.05), but it did not affect the fertilization percentages obtained in this experiment. In
conclusion, our study suggests that oocytes of the Lidia cattle breed can be obtained, matured and fertilized following
standard protocols previously used in other cattle breeds
Compaction caused by soil tillage and seedbed preparation: effects on weed emergence in a barley crop
El objetivo principal de este trabajo fue evaluar los efectos de la compactación producida por la frecuencia de pases y el tipo de apero utilizado en la siembra del cereal, sobre la emergencia de las malas hierbas. Se utilizó un diseño en parcelas subdivididas con 4 repeticiones, con la labor primaria (fresa vs. cultivador) en parcelas principales y el pase de rulo (liso vs. pratenses) en subparcelas. Se tomaron datos de malas hierbas (densidad, biomasa) y de propiedades físicas del suelo (compactación, densidad aparente). Los resultados no han mostrado diferencias debidas a la labor primaria en ninguna de las variables analizadas, pero sí en función del tipo y frecuencia de pases de rulo, observándose menor densidad y biomasa de malas hierbas cuanto mayor era el número de pases de rulo, especialmente el liso, coincidiendo con los suelos más compactados. Sin embargo, parece existir un límite en el cual dejan de producirse efectos significativos debido a una sobrecompactación (e.g. doble pase de rulo y zona de rodada).The main objective of this work was to evaluate the effects of the compaction produced by the frequency of passes and the type of implement used in seedbed preparation, on weed emergence. A split-plot design with 4 replications was used, with the primary tillage (cultivator vs. rotary tiller) in main plots and rolling (flat roller vs. Cambridge roller) in subplots. Weeds data (density, biomass) and soil physical properties (compaction, bulk density) were assessed. The results showed no differences due to the primary tillage in any of the analyzed variables. However, the type and frequency of roller passes resulted in significant differences in weed abundance, with lower weed density and biomass when the number of roller passes was greater (especially flat roller), which coincided with the higher compaction. However, it seems to be a limit at which significant effects no longer occur due to an overcompaction (e.g. double roller pass and tractor wheel traffic)
Modeling hydrodynamics and biochemical reactions in a Flat Plate Bioreactor
Modeling the complex interactions between biochemical reactions and hydrodynamics is the key to optimize biofiltration systems performance. In this work, biological kinetics expressions were implemented into Computational Fluid Dynamics (CFD) model as transport equations, including convective and diffusive terms. Previously, activity within the biofilm of a flat plate bioreactor (FPB) was experimentally investigated measuring dissolved oxygen (DO) profiles by means of microsensors and under common operating conditions. Moreover, a mathematical model to describe mass transport and metabolic activity in the FPB was developed and their parameters were fitted from experimental results. Then, a CFD model, combining hydrodynamics and biochemical reactions, was developed and solved to simulate local transient flow and dynamic behaviors of biofilm growth and substrate (glucose) biodregradation in the FPB. The CFD simulation results were evaluated by studying hydrodynamics characterization in the FPB and comparing simulated DO profiles with experimental DO profiles within the biofilm section. The hydraulic behaviour corresponds to a laminar flow and simulated DO profiles illustrate a satisfactory agreement with experimental data for different biofilm densities. Glucose and oxygen biodegradation and biomass growth along the bioreactor were described using the CFD model.Peer ReviewedPostprint (published version
Ovarian follicular dynamics in repeat breeder cow: ultrasonography and progesterone level
The aim of this study was to examine follicular development patterns in eighteen repeat breeder cows through spontaneous oestrus cycles. Ovarian ultrasonographic examinations over 32 days after artificial insemination revealed that two follicular waves were the predominant patterns in animals with this syndrome (72.2 percent). Cycles with one or four waves rarely appeared. The ovulatory follicular diameter (day 0) was larger (p<0.01) in cycles with a small number of waves; no differences were detected between ovulatory and anovulatory dominant follicles. Progesterone plasmatic concentrations were determined by RIA and differences were not significant when cycles with two or three waves were compared. The number of follicular waves was higher (2 or 3 waves) with longer interovulatory intervals (22.3 ± 1.89 vs 23.0 ± 2.0; n.s.) and older cows (7.0 ± 2.64 vs 4.38 ± 1.66 years; p<0.05). Mean ovulatory follicular diameter was 1.78 ± 0.36 cm. It can be concluded that cows with the repeat breeder cow syndrome more frequently present two follicular wavesEl objetivo de este trabajo era caracterizar los patrones de desarrollo folicular en 18 vacas repetidoras de celos a lo largo de ciclos sexuales espontáneos. Se llevaron a cabo exámenes ecográficos de los ovarios durante 32 días posteriores a la inseminación, observándose que el patrón de dos ondas era el más frecuente en vacas repetidoras alcanzando un 72,2 p.100, mientras que los de 3 ondas estuvieron presentes en el 16,6 p.100 de los ciclos estudiados. Se registraron ciclos con 1 y 4 ondas, aunque esta condición es muy poco frecuente. El diámetro del folículo ovulatorio fue mayor en ciclos con menos número de ondas (p<0,01); no se detectaron diferencias entre folículos dominantes ovulatorios o anovulatorios. Las concentraciones de progesterona no mostraron diferencias entre los distintos patrones de crecimiento folicular. Se apreció que los ciclos con más ondas foliculares estaban acompañados de intervalos interovulatorios más largos y aparecía en vacas más viejas. El diámetro folicular ovulatorio medio alcanzó 1,78 ± 0,36 cm. Los resultados permiten afirmar que la dinámica folicular más frecuente en vacas repetidoras es la de dos ondas
Sol-gel coatings for protection and bioactivation of metals used in orthopaedic devices
The aim of this work is the production and characterisation of sol-gel coatings for protection and bioactivation of metals used as standard surgical implant materials, such as stainless steel 316 L (ASTM F138), Co based alloys (ASTM F75) and titanium alloy Ti-6A1-4V (ASTM F67). These films should both prevent degradation of the substrates by wear or corrosion, and bioactivate the material for inducing the formation of a hydroxyapatite (HA) rich layer onto the material surface, thereby permitting a natural bonding to living tissues. Formation of HA layers can be observed on performing in vitro tests by soaking the material in simulated body solutions. The work describes the development of coatings containing bioactive glass and glass-ceramic particles in hybrid methyl-triethoxysilane (MTES) and tetraethylorthosilicate (TEOS) acidic sol, applied by dip-coating to surgical alloys, AISI 316 L, ASTM F75 and ASTM 67, with the aim of accomplishing both high corrosion resistance of the metal in the body environment and adhesion of the implant to the surrounding tissue. The performance of the coated metal was evaluated in vitro by electrochemical techniques including potentiodynamic polarisation curves and electrochemical impedance spectroscopy, to follow the formation of hydroxyapatite on the surface, as well as the in vitro release of ions by plasma atomic emission spectroscopy (ICP-MS) after up to one year of immersion. In vivo behaviour was evaluated by subcutaneous tests and endomedullar implantation in Hokaido rats to study possible rejection reactions and natural bonding to living tissue.Peer Reviewe
Interrelationship Between Broadband NIRS Measurements of Cerebral Cytochrome C Oxidase and Systemic Changes Indicates Injury Severity in Neonatal Encephalopathy
Perinatal hypoxic ischaemic encephalopathy (HIE) is associated with severe neurodevelopmental problems and mortality. There is a clinical need for techniques to provide cotside assessment of the injury extent. This study aims to use non-invasive cerebral broadband near-infrared spectroscopy (NIRS) in combination with systemic physiology to assess the severity of HIE injury. Broadband NIRS is used to measure the changes in haemodynamics, oxygenation and the oxidation state of cytochrome c oxidase (oxCCO). We used canonical correlation analysis (CCA), a multivariate statistical technique, to measure the relationship between cerebral broadband NIRS measurements and systemic physiology. A strong relationship between the metabolic marker, oxCCO, and systemic changes indicated severe brain injury; if more than 60 % of the oxCCO signal could be explained by the systemic variations, then the neurodevelopmental outcome was poor. This boundary has high sensitivity and specificity (100 and 83 %, respectively). Broadband NIRS measured concentration changes of the oxidation state of cytochrome c oxidase has the potential to become a useful cotside tool for assessment of injury severity following hypoxic ischaemic brain injury
A quality of service assessment technique for large-scale management of multimedia flows
The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-540-75869-3_15Proceedings of 10th IFIP/IEEE International Conference on Management of Multimedia and Mobile Networks and Services, MMNS 2007, San José, USA, October 31 - November 2, 2007This paper presents the concept and preliminary experiments of a system for assessing on the Quality of Service of multimedia flows. The goal is to devise a mechanism that allows a service provider to take action whenever poor quality of service is detected in the delivery of multimedia flows. Such procedure is fully automatic since it is based on a goodness-of-fit test between source and destination packet interarrival histograms. If the null hypothesis of the test is accepted the flow is marked as in good standing, otherwise it is marked as anomalous and the network management system should take action in response. The proposed technique is analyzed in terms of hardware complexity and bandwidth consumption. The results show this technique is feasible and easily deployable at a minimum hardware and bandwidth expense.The authors would like to acknowledge the support of the Comunidad Autónoma de
Madrid to this work, under project e-Magerit (S-0505/TIC/000251)
Rheological properties of biofilms: steady and transient shear flow modeling
Premi al millor poster en la 7th Internacional Conference on Biotechniques for Air Pollution Control and BioenergyPeer ReviewedAward-winningPostprint (published version
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