6,014 research outputs found

    Seasonal Variation of Essential Oil Yield and Composition of Sage (Salvia officinalis L.) Grown in Castilla - La Mancha (Central Spain)

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    Links between phenology, yield and composition of the essential oil of common sage, Salvia officinalis L., grown in Guadalajara (Central Spain) were determined in the different phases of the biological cycle during one year. Data showed an average yield about 1.0%. The analysis of the oil components was carried out by GC-FID and GC/MS. The main oil constituent was alpha thujone (40.1 - 46.5%). Other identified compounds are beta pinene (2.6 - 4.5%), cineole (3.5 - 8.7%), beta thujone (4.1 - 5.6%), camphor (4.1 - 8.0%), borneol (1.3 - 3.7%), alpha humulene (3.8 - 7.3%), viridiflorol (3.4-12.6%) and manool (0.1-4.5%). The highest yield of oil was obtained in the period of full flowering and the highest concentration of alpha thujone in the period of initial flowering

    Un enfoque de trabajo en el aula : la actividad científica escolar

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    La investigación que se presenta tiene como objetivo analizar la actividad científica escolar que se desarrolla con un grupo de estudiantes de 14 y 15 años mientras trabajaban el tema de la nutrición en un Instituto de Educación Secundaria de Barcelona (España). La profesora utiliza diversas modalidades educativas, realiza experimentos, explica, presenta un vídeo a sus estudiantes. A través de esas actividades, obtiene textos, resúmenes e informes de prácticas; estos materiales constituyen los datos para nuestra investigación. El análisis de las producciones de los estudiantes nos sirve para interpretar cómo se construye la actividad científica escolar a partir de sus cuatro elementos fundamentales: la experiencia, los modelos teóricos, las metas y los lenguajes. En esta comunicación se presentan resultados empíricos en relación con el análisis de una intervención didáctica centrada en la habilidad cognitivolingüística del resumen

    An Effective Field Theory Look at Deep Inelastic Scattering

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    This talk discusses the effective field theory view of deep inelastic scattering. In such an approach, the standard factorization formula of a hard coefficient multiplied by a parton distribution function arises from matching of QCD onto an effective field theory. The DGLAP equations can then be viewed as the standard renormalization group equations that determines the cut-off dependence of the non-local operator whose forward matrix element is the parton distribution function. As an example, the non-singlet quark splitting functions is derived directly from the renormalization properties of the non-local operator itself. This approach, although discussed in the literature, does not appear to be well known to the larger high energy community. In this talk we give a pedagogical introduction to this subject.Comment: 11 pages, 1 figure, To appear in Modern Physics Letters

    Dynamics of entanglement in quantum computers with imperfections

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    The dynamics of the pairwise entanglement in a qubit lattice in the presence of static imperfections exhibits different regimes. We show that there is a transition from a perturbative region, where the entanglement is stable against imperfections, to the ergodic regime, in which a pair of qubits becomes entangled with the rest of the lattice and the pairwise entanglement drops to zero. The transition is almost independent of the size of the quantum computer. We consider both the case of an initial maximally entangled and separable state. In this last case there is a broad crossover region in which the computer imperfections can be used to create a significant amount of pairwise entanglement.Comment: 4 pages, 4 figure

    Is there an association between daytime napping, cognitive function, and brain volume? A Mendelian randomization study in the UK Biobank

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    OBJECTIVES: Daytime napping has been associated with cognitive function and brain health in observational studies. However, it remains elusive whether these associations are causal. Using Mendelian randomization, we studied the relationship between habitual daytime napping and cognition and brain structure. METHODS: Data were from UK Biobank (maximum n = 378,932 and mean age = 57 years). Our exposure (daytime napping) was instrumented using 92 previously identified genome-wide, independent genetic variants (single-nucleotide polymorphisms, SNPs). Our outcomes were total brain volume, hippocampal volume, reaction time, and visual memory. Inverse-variance weighted was implemented, with sensitivity analyses (Mendelian randomization-Egger and Weighted Median Estimator) for horizontal pleiotropy. We tested different daytime napping instruments to ensure the robustness of our results. RESULTS: Using Mendelian randomization, we found an association between habitual daytime napping and larger total brain volume (unstandardized ß = 15.80 cm3 and 95% CI = 0.25; 31.34) but not hippocampal volume (ß = −0.03 cm3 and 95% CI = −0.13;0.06), reaction time (expß = 1.01 and 95% CI = 1.00;1.03), or visual memory (expß = 0.99 and 95% CI = 0.94;1.05). Additional analyses with 47 SNPs (adjusted for excessive daytime sleepiness), 86 SNPs (excluding sleep apnea), and 17 SNPs (no sample overlap with UK Biobank) were largely consistent with our main findings. No evidence of horizontal pleiotropy was found. CONCLUSIONS: Our findings suggest a modest causal association between habitual daytime napping and larger total brain volume. Future studies could focus on the associations between napping and other cognitive or brain outcomes and replication of these findings using other datasets and methods

    El movimiento MAKER desde la perspectiva digital: los docentes y la construcción de recursos educativos

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    La presente propuesta, se centra en la posibilidad de que el docente asuma el reto de construir sus recursos educativos, usarlos en sus clases y compartirlos con otros docentes, para lo cual requiere ante todo su creatividad, entusiasmo y conocimientos básicos en el uso de software de autor. Esto también aplica para los estudiantes, ya que el manejo de este tipo de herramientas informáticas les permite aprender colaborativamente construyendo recursos para compartir con sus compañeros, aprender juntos y hacer procesos de coevaluación permanentes
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