Efectos de cortocircuito en transformadores verificados con el análisis de respuesta en frecuencia

En el presente trabajo, se expone un caso de estudio de pruebas de SFRA en un transformador de distribución previo y posterior a un ensayo de cortocircuito de laboratorio. Los resultados y conclusiones verifican la importancia que reviste la prueba de SFRA para determinar (diagnóstico) cambios en la condición mecánica al cabo de un evento de cortocircuito.Instituto de Investigaciones Tecnológicas para Redes y Equipos Eléctricos (IITREE

Effectiveness of the application of massage therapy and kinesitherapy by parents on premature neonates: a research protocol

Aim: The study aims to analyse the efficacy of massage therapy and kinesitherapy applied by parents of premature infants admitted to hospital. Background: Premature newborns suffer early somatic deprivation that has adverse effects on their growth and development and that also has a negative impact on the emotional state of their parents. Massage therapy and kinesitherapy is beneficial in alleviating somatic deficit and facilitates the bond between parents and newborns. Design: A quasi-experimental community intervention trial will be conducted in a neonatology unit. Methods: This study will compare the benefits of a 15-min massage protocol applied by parents with the usual medical and nursing care given by neonatal units for premature babies. The evaluation of neuromotor development will take place through the Spanish Premie-Neuro scale. The determination of weight, size, and head circumference will be based on the unit's usual procedures. Discussion: If the implementation of a massage therapy and kinesitherapy protocol is effective in promoting the growth and development of hospitalized premature infants, the results of this study could give an impetus for the inclusion of somatic stimulation in the usual nursing care given for preterm infants. Impact: Prematurity and its associated morbidity pose a major global public health problem. Somatic and kinaesthetic stimulation has beneficial effects on anthropometric and neuromotor development in preterm infants. The results will have a positive impact on premature neonates and their families, both during the hospitalization, and a positive socio-economic effect throughout their lives (education, work, disability).SIWe thank the Neonatal Care Unit of the León University Hospital for taking part in this project, as well as all the nurses who participated for their efforts and dedication in collecting data. We are especially grateful to the premature newborns and their family members who kindly contributed to this study with their participation

Evaluation of the qualitative and quantitative effectiveness of three media of centrifugation (Maxifreeze, Cushion Fluid Equine, and PureSperm 100) in preparation of fresh or frozen-thawed brown bear spermatozoa

P. 1119-1128Centrifugation is a crucial procedure in sperm cryopreservation protocols of brown bear (Ursus arctos), because the semen must be processed to increase sperm concentration and/or clean urine-contaminated samples. The efficacy of three media for centrifugation (Maxifreeze [IMV technologies, L'Aigle, France], Cushion Fluid Equine (Minitübe, Tiefenbach, Germany), and PureSperm [Nidacon, Gothenburg, Sweden]) on the quality of bear spermatozoa was evaluated. In experiment one, two cushioned media used for protecting against mechanical stress during centrifugation were analyzed. In experiment two, a density gradient based on PureSperm was assessed in relation to the maximum retrieval and the quality of fresh spermatozoa, and the freezability of the spermatozoa selected in this density gradient was studied in experiment three. Finally, the selection of frozen-thawed sperm using PureSperm was analyzed in experiment four. Our results indicate that the use of dense isotonic cushion solutions (Maxifreeze, Cushion Fluid Equine) in centrifugation did not improve the quality of recovered spermatozoa compared with standard centrifugation. However, a density gradient prepared with PureSperm improved the quality of spermatozoa in fresh semen and frozen-thawed semen, but the spermatozoa selected from the fresh sample with this density gradient did not show a better resistance to freezing with this density gradient in comparison with the control sample.S

The antioxidant effects of soybean lecithin- or low-density lipoprotein-based extenders for the cryopreservation of brown-bear (Ursus arctos) spermatozoa

P. 1185-1193Egg yolk low-density lipoproteins (LDL) and soybean lecithin were evaluated as replacements for egg yolk in extenders used for the cryopreservation of brown-bear spermatozoa. The motility, viability and acrosomal status of post-thawed spermatozoa were analysed, and an egg-yolk extender was used as a control. The total antioxidant capacity of these extenders was tested. Soybean lecithin showed an effect that was dependent on the soybean concentration (2%, 3.5% and 5%) and source (Type A: 24% l-α-phosphatidylcholine, and Type B: 14–23% l-α-phosphatidylcholine). Only semen cryopreserved with 5% Type A soybean exhibited a sperm motility similar to that of semen cryopreserved in egg-yolk-based extender after thawing, although the sperm viability and acrosome status were not as high. Semen frozen in an extender containing LDL (10–15%) exhibited improved sperm viability in comparison with the control, but sperm motility was lower. The LDL-based extender exhibited a higher anti-oxidant activity than the egg-yolk extender and soy lecithin-based extenders. The extenders with higher anti-oxidant activity showed improvements in frozen sperm viability but lower semen motility. These results indicate that soybean lecithin did not have the same protective effect as egg yolk during the freezing of brown-bear spermatozoa but suggest that LDL (10–15%) could be a useful substitute for egg yolk in these extenders

Quality of frozen-thawed semen in brown bear is not affected by timing of glycerol addition

P. 1561-1565We have tested several freezing protocols for brown bear semen, modifying the time when glycerol was added (before and after cooling to 5 °C). No differences were found among protocols, indicating a good tolerance of brown bear semen to glycerol. This finding indicates that freezing protocols for brown bear semen could be modified to fit practical solutions which would facilitate preparation of the seminal samples in the field with the addition of glycerol at ambient temperature.S

Decentralized Control of Offshore Wind Farms Connected to Diode-Based HVdc Links

This paper presents a novel decentralized control for offshore wind farms connected to the onshore grid through a high-voltage dc link by means of a diode rectifier. The proposed control system is implemented in each wind turbine generator system (WTGS). The capacitor placed at the filter of the wind turbine front-end converter is used for the proposed control implementation. Frequency control is achieved by aligning the capacitor voltage vector along a reference axis rotating at the reference frequency. Then, a frequency-reactive power droop control allows the synchronization of all the WTGSs. On the other hand, this droop strategy also leads to total reactive power sharing among WTGSs without relying on communications. An additional secondary frequency control is also implemented to compensate the frequency deviation caused by the droop control. The proposed control system has been validated by simulation and results demonstrate the appropriate performance even during start-up and faults

The addition of heat shock protein HSPA8 to cryoprotective media improves the survival of brown bear (Ursus arctos) spermatozoa during chilling and after cryopreservation

P. 541-550The Cantabrian brown bear survives as a small remnant population in northern Spain and semen cryopreservation for future artificial insemination is one of the measures being implemented for conservation of this species. As part of this program we investigated the value of adding heat shock protein A8 (HSPA8) to media (N-[Tris(hydroxymethyl)methyl]-2-aminoethanesulfonic acid-TRIS-fructose with 20% egg yolk) used for chilling and cryopreserving the spermatozoa. Semen samples from eight brown bears were obtained by electroejaculation during the breeding season. In experiment 1, we tested three concentrations of HSPA8 (0.5, 1, and 5 μg/mL) to determine whether sperm motility (computer assisted sperm analysis system) and sperm survival could be improved during refrigeration (5 °C) up to 48 hours. Results showed that sperm viability (test with propidium iodide) was improved by the addition of 0.5 and 5 μg/mL HSPA8. In experiment 2, HSPA8 was added to the cryopreservation media (6% final glycerol concentration) before the freezing process. Though there were no differences in sperm viability immediately after thawing (analyses to 0 hours), plasma membrane permeability (test with YO-PRO-1) was significantly lower by the presence of HSPA8 (1 μg/mL) and acrosomal damage (test with peanut agglutinin-fluorescein isothiocyanate conjugate) was reduced by higher concentrations of HSPA8 (1 and 5 μg/mL) (analyses after thermal stress test incubating over 2 hours to 37 °C). In experiment 3, results of a simple progression test carried out through artificial mucus (hyaluronic acid 4 mg/mL) showed a significant decrease in the total number of sperm able to swim a distance of 0.5 to 2 cm through a capillary tube for all HSPA8-based extenders. Nevertheless, the distance traveled by the vanguard spermatozoa, which represent a highly motile subpopulation, was restored by the inclusion of 1 and 5 μg/mL HSPA8 in the cryopreservation media. Thus, the HSPA8 addition to extender improves the quality of brown bear (Ursus arctos) sperm during chilling (viability) and after cryopreservation (number of sperm with damaged acrosomes and “apoptotic-like” changes)S

An unsaturated four-coordinate dimethyl dimolybdenum complex with a molybdenum-molybdenum quadruple bond

We describe the synthesis and the molecular and electronic structures of the complex [Mo2Me2{mu-HC(NDipp)(2)}(2)] (2; Dipp=2,6-iPr(2)C(6)H(3)), which contains a dimetallic core with an Mo-Mo quadruple bond and features uncommon four-coordinate geometry and has a fourteen-electron count for each molybdenum atom. The coordination polyhedron approaches a square pyramid, with one of the molybdenum atoms nearly co-planar with the basal square plane, in which the trans coordination position with respect to the Mo-Me bond is vacant. The other three sites are occupied by two trans nitrogen atoms of different amidinate ligands and the methyl group. The second Mo atom occupies the apex of the pyramid and forms an Mo-Mo bond of length 2.080(1) angstrom, consistent with a quadruple bond. Compound 2 reacts with tetrahydrofuran (THF) and trimethylphosphine to yield the mono-adducts [Mo2Me(mu-Me){mu-HC(NDipp)(2)}(2)(L)] (3 center dot THF and 3 center dot PMe3, respectively) with one terminal and one bridging methyl group. In contrast, 4-dimethylaminopyridine (dmap) forms the bis-adduct [Mo2Me2{mu-HC(NDipp)(2)}(2)(dmap)(2)] (4), with terminally coordinated methyl groups. Hydrogenolysis of complex 2 leads to the bis(hydride) [Mo2H2{mu-HC(NDipp)(2)}(2)(thf)(2)] (5 center dot THF) with elimination of CH4. Computational, kinetic, and mechanistic studies, which included the use of D-2 and of complex 2 labelled with C-13 (99%) at the Mo-CH3 sites, supported the intermediacy of a methyl-hydride reactive species. A computational DFT analysis of the terminal and bridging coordination of the methyl groups to the Mo Mo core is also reported

New data about the geomorphological and paleoenvironmental evolution of the Cantabrian Coast during MIS 6-4: the Cobiḥeru Natural Monument (Asturias)

Se proporcionan nuevos datos sobre la geomorfología y evolución paleoambiental de la Costa Cantábrica durante el MIS 6–4 a partir del modelo espeleogenético de la Cueva de Cobḥi eru, incluyendo: (1) la identificación de 2 fases de relleno de la cueva relacionadas con condiciones más frías y etapas de nivel del mar bajo a 60–70 y 130–150 ka, (2) el inicio de un descenso del nivel del Mar Cantábrico en la transición entre el MIS 5-4, (3) la presencia de un ambiente abierto con poca vegetación en torno a 65 ka (MIS 4), (4) el descubrimiento del Elona quimperiana más antiguo, indicando el desarrollo de bosque caducifolio húmedo hace más de 350 ka, y (5) la relación entre la erosión de los abanicos torrenciales que cubrían el karst y la entrada de fauna fría a las cuevas de la costa de AsturiasNew data about the geomorphology and paleoenvironmental evolution of the Cantabrian Coast for the MIS 6-4 interval is derived from the speleogenetical model of the Cobḥi eru Cave. This data includes: (1) the identification of 2 phases of cave sedimentary infill related to cold conditions and global sea-level lowstand at ca. 60–70 and 130–150 ka, (2) set the timing for the beginning of sea-level lowering in the Cantabrian Sea in MIS 5-4 transition , (3) evidence of an open landscape with scarce vegetation around 65 ka (MIS 4), (4) the discovery of the oldest Elona quimperiana site, which suggest the development of wet deciduous forest in this coastal setting prior to 350 ka, and (5) to establish a link between karst exhumation due to erosion of overlying fluvial sediments and the introduction of the cold-adapted fauna in the coast caves of Asturia

Aproximación del alumno al diseño por ordenador de conjuntos mecánicos reales

Proyecto de Innovación Docente en la asignatura Diseño Asistido por ComputadorEste Proyecto de Innovación Docente ha sido llevado a cabo en el curso académico 2004-05con los alumnos de la asignatura de“Diseño Asistido por Computador” de 2º de IngenieríaTécnica Industrial (Mecánica), que se imparte en el primer cuatrimestre. En él se ha inducido alos alumnos al trabajo en grupo sobre un problema de modelado virtual de un conjunto mecánico real, para el que es necesarioaprender y aplicar las herramientas básicas propiasde la asignatura. Además, el alumno puede, como ha ocurrido en muchos casos, profundizar de forma autodidacta en el empleo de algunas herramientas derivadas que por su complejidad o extensión, no se desarrollan en el marco teórico de la asignatura. La consecución de este doble objetivo ha supuestoun acercamiento al crédito europeo ECTS, basado en el trabajorealizado por el estudiante en su proceso de aprendizaje. El análisis de losresultados académicos y de las encuestas realizadas a los alumnos tras la experiencia, permiten emitir una valoración positiva de la metodología docente propuesta