6,407 research outputs found
Determinación de la estructura genética de las poblaciones silvestres españolas de Castanea sativa mediante isoenzimas
The genetic variability within and among 17 wild Spanish chestnut stands was examined by isozyme analysis, with the goals of describing their geographic structure and designing conservation and management strategies. Measures of genetic diversity such as allelic richness, heterozygosity, polymorphism, F-statistics, D-statistics, gene flow, clustering using Nei’s genetic distances and a method based on an Monte Carlo Markov Chain algorithm and the contributions of each stand to diversity and allelic richness were all used. Wild Spanish chestnut populations displayed heterogeneity of allele frequencies between them, high levels of genetic diversity and high differentiation (Fst = 0.15) compared with populations from other western European countries such as France and Italy. The two clustering methods allowed the identification of three clusters: a Mediterranean cluster, a northern Spanish cluster and the southern Galician cluster. The highest heterozygosity and allelic richness were found in the North, especially in the southern Galician cluster. Several areas can be recommended for inclusion in the network of Conservation Units: Fraga de Catasós, representing the southern Galician cluster; Fragas do Eume, representing the northern Spanish cluster; and Hervás or El Tiemblo, representing the Mediterranean cluster.La variabilidad genética entre y dentro de 17 rodales de castaño silvestre muestreados en poblaciones españolas se examinó mediante el análisis de polimorfismos isoenzimáticos con la finalidad de describir la estructura geográfica y diseñar estrategias de conservación y manejo. Se calcularon la riqueza alélica, heterocigosidad, polimorfismo, la estadística F y D, el flujo genético y se realizaron análisis de agrupación de poblaciones utilizando la distancia genética de Nei y un método basado en el algoritmo Monte Carlo Markov Chain, y finalmente se calcularon las contribuciones de cada rodal a la diversidad y riqueza alélica.
Las poblaciones silvestres de castaño españolas presentaron heterogeneidad de frecuencias alélicas entre ellas, elevados niveles de diversidad genética y de diferenciación (Fst = 0.15) comparadas con otras poblaciones del Oeste de Europa. Se identificaron tres grupos de poblaciones: el grupo Mediterráneo, el grupo del Norte y del Sur de Galicia. La mayor heterocigosidad y riqueza alélica está en el Norte, principalmente en el grupo del Sur de Galicia. Se recomiendan varias áreas para incluir en la red de Unidades de Conservación: Fraga de Catasós, en representación del grupo Sur de Galicia; las Fragas do Eume, representando el grupo del Norte; y Hervás o el Tiemblo en representación del grupo Mediterráneo
Magnetic Surfaces in Stationary Axisymmetric General Relativity
In this paper a new method is derived for constructing electromagnetic
surface sources for stationary axisymmetric electrovac spacetimes endowed with
non-smooth or even discontinuous
Ernst potentials. This can be viewed as a generalization of some classical
potential theory results, since lack of continuity of the potential is related
to dipole density and lack of smoothness, to monopole density. In particular
this approach is useful for constructing the dipole source for the magnetic
field. This formalism involves solving a linear elliptic differential equation
with boundary conditions at infinity. As an example, two different models of
surface densities for the Kerr-Newman electrovac spacetime are derived.Comment: 15 page
Effect of plyometric training on sprint performance
El propósito del estudio fue investigar el efecto del entrenamiento pliométrico en la velocidad en estudiantes de la Facultad de Ciencias de la Actividad Física y del Deporte de la Universidad de León, en un periodo de entrenamiento de 4 semanas, con dos sesiones semanales, en una muestra formada por 18 sujetos (23 ± 1 año), divididos en dos grupos, el Grupo de Entrenamiento, compuesto por 13 sujetos y el Grupo Control, formado por 5 sujetos.
Los resultados analizados en un Test de velocidad de 30m. lisos revelaron diferencias significativas en el Grupo Entrenamiento después de las sesiones de entrenamiento, aumentando la velocidad de 0-10m. y de 0-30m. (p<0,05). En cuanto a la aceleración también se obtuvieron cambios significativos, con una mejora de 0-10m. (p<0,05). Estos resultados demuestran que el entrenamiento pliométrico puede aumentar la velocidad de 0-10m. y de 0-30m., reduciendo el tiempo en recorrer dicha distancia.The purpose of this study was to research on the effect of plyometric training on the velocity of students from the Faculty of the Sciences of Physical Activity and Sport of León University. The training lasted four weeks, with two sessions per week. Eighteen participants (23± 1 years of age) were assigned to two groups; a Training Group, composed of fifteen subjects and a Control Group, of five subjects.
The results, analyzed in a Velocity Test of a 30m sprint, revealed significant differences in the Training Group after the training sessions, the velocity having increased about 0-10m., 0-30m. (p<0,05). With regard to acceleration, significant differences were also observed, with an improvement of 0-10m. (p<0,05).
These results showed that plyometric training can increase the velocity about 0-10m. and 0-30m., reducing the time to cover said distance
Cotilo recubierto con hidroxiapatita de la artroplastia Omnifit: resultados a medio plazo
Las cúpulas acetabulares roscadas han mostrado malos resultados en períodos
medios de evolución. Aunque la sujeción inmediata es excelente, con el paso del tiempo
se ha comprobado la ausencia de fijación, mostrando un alto porcentaje de movilizaciones.
Una alternativa para evitar esos fracasos es el recubrimiento de estos cotilos con
hidroxiapatita. Hemos revisado clínica y radiográficamente 36 casos de artroplastias
Omnifit con cotilo roscado y recubierto de hidroxiapatita, con un tiempo medio de seguimiento
de 58 meses. Diez pacientes presentaban dolor en región inguinal. Sólo el 63,9% de
los cotilos se encontraban radiográficamente integrados, habiendo sufrido una clara movilización
seis que precisaron cirugía de revisión acetabular; otros siete mostraban signos
radiológicos de probable inestabilidad.
El recubrimiento con hidroxiapatita no asegura una buena fijación en los cotilos roscados
Omnifit por lo que recomendamos componentes acetabulares implantados a presión
con posibilidad de sujeción adicional con tornillos.The threaded acetabular cups have shown mid-term bad results. Though
the immediate fixation is excellent, as time goes by it has been proven the absence of fixation,
appearing a high percentage of mobilizations. An alternative to avoid those failures
is the hydroxyapatite coated implant. We have analysed clinically and radiographically
36 cases of Omnifit arthroplasties with cup threaded and coated with hydroxyapatite
with an average time of follow-up of 58 months. Ten patients had pain in the hip. Only
63.9% of the acetabular cups were found to be radiographically integrated, six having suffered
a clear mobilization requiring surgical review. Seven showed radiological signs of
probable instability. The hydroxytapatite coatings does not assure a good fixation in the
Omnifit threaded cups, therefore we recommend press fit acetabular components with
the possibility of additional fixation with screws
Working Environment in Nursing: Needs Improvement?
Background: Knowing the quality of life of professionals is important because it is related to job performance, better results, and greater productivity, which results in better patient care. Objective: To know the Professional Quality of Life perceived by the nurses at the Geriatric Hospital of Toledo (Spain). Method: A descriptive cross-section study was employed to measure the Professional Quality of Life of all healthcare nurses (69 in total) at the Geriatric Hospital of Toledo. The questionnaire used as a measuring instrument was the Professional Quality of Life - 35. The data obtained was analyzed by means of: descriptive statistics, single-factor ANOVA variance analysis, T Student tests, and simple and multiple regression analysis. The study was approved by both the research commission and the ethics commission at the Hospital Complex of Toledo. Participation in the study on behalf of the nursing staff was voluntary. Results: In total, 45 responses were obtained (65.2%). The overall mean score measured the perceived Professional Quality of Life to be low. In relation to the three dimensions evaluated in the study, the highest average found was in “intrinsic motivation,” followed by “workload”, and then “management support.” In the multivariate analysis, “management support” was shown as the most influential factor in the Professional Quality of Life with a 23% influence (P<0.001), followed by workload with 9% (P = 0.01). Conclusions: The professionals at the participating center perceive their workplace as having an elevated degree of responsibility, a large quantity of work, a high occurrence of rushes and fatigue, and all this with little support on behalf of management. Promotions are scarce or the policies for receiving a promotion are inadequate. The perception of Professional Quality of Life in nursing is low. The obtained results indicate a need for an organizing cultural change based on participation, motivation, and increased management support
Sphere rolling on the surface of a cone
We analyse the motion of a sphere that rolls without slipping on a conical
surface having its axis in the direction of the constant gravitational field of
the Earth. This nonholonomic system admits a solution in terms of quadratures.
We exhibit that the only circular of the system orbit is stable and furthermore
show that all its solutions can be found using an analogy with central force
problems. We also discuss the case of motion with no gravitational field, that
is, of motion on a freely falling cone.Comment: 12 pages, 2 figures, to be published in Eur J Phy
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