7,070 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

    Recent developments in nanostructured materials for high-performance thermoelectrics

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    This highlight discusses recent trends in the search for new high-efficiency thermoelectric materials. Thermoelectric materials offer considerable attractions in the pursuit of a more efficient use of existing energy resources, as they may be used to construct power-generation devices that allow useful electrical power to be extracted from otherwise waste heat. Here, we focus on the significant enhancements in thermoelectric performance that have been achieved through nanostructuring. The principal factor behind the improved performance appears to be increased phonon scattering at interfaces. This results in a substantial reduction in the lattice contribution to thermal conductivity, a low value of which is a key requirement for improved thermoelectric performance

    Greening of the Solid Waste Management in Batangas City

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    Management of solid wastes in the Philippines has long been a responsibility of the Local Government Units in the country since the enactment of Republic Act 9003 also known as the Ecological Solid Waste Management Act of 2002. In support to the local government of Batangas City, this study was conducted to propose a plan of action that will enhance the level of implementation of solid waste management in the city, lessen the harmful effects to the environment and health of the people and find solutions to problems encountered in its implementation .  The descriptive survey method was used with 204 respondents taken by stratified sampling from selected 69 barangays. A Likert scale instrument was used to measure the level of implementation of solid waste management practices of the residents and the problems encountered by the residents in the implementation of solid waste management practices. A checklist determine the effects of the implementation of solid waste management practices to the environment and health of the people Data analysis made use of frequency distribution, weighted mean and ANOVA. From the findings gathered on the level of implementation of solid waste management and the observed effects to the environment and health of the people including the problems encountered in its implementation, a plan of action was proposed with the hope of enhancing the level of implementation of solid waste management thereby lessening its harmful effects and problems to health and environment. Keywords: level of implementation /solid waste / solid waste managemen

    Ball milling as an effective route for the preparation of doped bornite: synthesis, stability and thermoelectric properties

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    Bornite, Cu5FeS4, is a naturally-occuring mineral with an ultralow thermal conductivity and potential for thermoelectric power generation. We describe here a new, easy and scalable route to synthesise bornite, together with the thermoelectric behaviour of manganese-substituted derivatives, Cu5Fe1-xMnxS4 (0 ≤ x ≤ 0.10). The electrical and thermal transport properties of Cu5Fe1-xMnxS4 (0 ≤ x ≤ 0.10), which are p-type semiconductors, were measured from room temperature to 573 K. The stability of bornite was investigated by thermogravimetric analysis under inert and oxidising atmospheres. Repeated measurements of the electrical transport properties confirm that bornite is stable up to 580 K under an inert atmosphere, while heating to 890 K results in rapid degradation. Ball milling leads to a substantial improvement in the thermoelectric figure of merit of unsusbtituted bornite (ZT = 0.55 at 543 K), when compared to bornite prepared by conventional high-temperature synthesis (ZT < 0.3 at 543 K). Manganese-substituted samples have a ZT comparable to that of unsubstituted bornite
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