Conformal mapping of ultrasonic crystals: confining ultrasound and cochlear-like wave guiding

Conformal mapping of a slab of a two-dimensional ultrasonic crystal generate a closed geometrical arrangement of ultrasonic scatterers with appealing acoustic properties. This acoustic shell is able to confine ultrasonic modes. Some of these internal resonances can be induced from an external wave source. The mapping of a linear defect produces a wave-guide that exhibits a spatial-frequency selection analogous to that characteristic of a synthetic "cochlea". Both, experimental and theoretical results are reported here.Comment: 4 pages, 4 figure

A semi-analytical perspective on massive galaxies at z∼0.55z\sim0.55

The most massive and luminous galaxies in the Universe serve as powerful probes to study the formation of structure, the assembly of mass, and cosmology. However, their detailed formation and evolution is still barely understood. Here we extract a sample of massive mock galaxies from the semi-analytical model of galaxy formation (SAM) GALACTICUS from the MultiDark-Galaxies, by replicating the CMASS photometric selection from the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS). The comparison of the GALACTICUS CMASS-mock with BOSS-CMASS data allows us to explore different aspects of the massive galaxy population at $0.5<z<0.6$, including the galaxy-halo connection and the galaxy clustering. We find good agreement between our modelled galaxies and observations regarding the galaxy-halo connection, but our CMASS-mock over-estimates the clustering amplitude of the 2-point correlation function, due to a smaller number density compared to BOSS, a lack of blue objects, and a small intrinsic scatter in stellar mass at fixed halo mass of $<0.1$ dex. To alleviate this problem, we construct an alternative mock catalogue mimicking the CMASS colour-magnitude distribution by randomly down-sampling the SAM catalogue. This CMASS-mock reproduces the clustering of CMASS galaxies within 1$\sigma$ and shows some environmental dependency of star formation properties that could be connected to the quenching of star formation and the assembly bias.Comment: 15 pages, 10 figures, 2 tables, submitted to MNRA

Caracterización de Quassia amara para su manejo sostenible en ecosistemas naturales y agroforestales en Costa Rica

Proyecto de Investigación (Código: 5402 – 2151 – 6201) Instituto Tecnológico de Costa Rica. Vicerrectoría de Investigación y Extensión (VIE). Escuela de Ingeniería en Agronomía, 2008El Hombre grande (Quassia amara) es una planta medicinal y tiene actividad biocida, la cual la hace ser de gran importancia en la producción de cultivos orgánicos. Sin embargo, existe una serie de limitaciones, como son la falta de una semilla apropiada para el establecimiento de las plantaciones. El objetivo principal de este proyecto fue caracterizar los genotipos de Quassia amara y su clonación. El estudio realizó una serie de evaluaciones para determinar la metodología para la micropropagación de esta planta, así como estudios preliminares de extracción de ADN para la caracterización molecular del hombre grande. Los resultados de estas investigaciones permitieron desarrollar una metodología para la extracción del ADN, pero no la caracterización molecular de los genotipos. Además, determinaron, que el explante recomendado para la micropropagación es el uso de nudos, la desinfección de estos explanes no se encuentra definida, el medio de cultivo para el establecimiento de nudos que dio el mejor resultado fue el medio de Gamborg o B5, suplementado con 1.5 mg/l de ANA

Tourmaline 40Ar/39Ar chronology of tourmaline-rich rocks from Central Iberia dates the main Variscan deformation phases

During crustal thickening, metapelites taken to depth release boron-bearing hydrothermal fluids because of progressive heating and dehydration. These fluids swiftly percolate upwards, especially if the crust is being actively deformed, to form tourmaline where the PT conditions and the chemical composition of the host-rock are favorable. The age of the so-formed tourmaline would record the age of the upward admittance of B-bearing fluids and, presumably, the age of the deformation. This process has been documented in the Martinamor Antiform of Central Iberia, a region where tourmaline-bearing rocks are particularly abundant. Metasomatic tourmaline from the Late Cambrian San Pelayo orthogneisses (zircon U-Pb age of 496 ± 5 Ma) yielded 40Ar/39Ar plateau ages at 370 ± 5 Ma and 342 ± 5 Ma. The first value represents the crystallization age of the tourmaline and is so far the most precise estimation of the age of crustal thickening in Central Iberia (D1). The second value reflects a partial loss of Ar caused by the second deformation phase (D2). Tourmaline from mylonitized and folded tourmalinites developed above D2 shear zones yield perturbed spectra with mean "plateau" ages of 347 ± 9 Ma and 342 ± 9 Ma which may represent either the resetting of older tourmaline or the formation of new tourmaline by focused boron metasomatism. After the metamorphic peak and simultaneously with the emplacement of the main granitoids of the Avila Batholith (310-315 Ma), another episode of boron metasomatism precipitated a new generation of tourmaline, which appears either concentrated in fine-layered tourmalinites (318 ± 2 Ma) or disseminated within Ediacaran-Cambrian metasediments (316 ± 2 Ma). The source of boron was the breakdown of previously formed tourmaline during melting reactions. Lastly, tourmaline from a leucogranitic body yielded a saddle-shaped age spectrum with a minimum age of ca. 296 Ma, roughly coeval with the youngest leucograni - tes. Although further work is required, our results suggest that tourmaline can be a useful chronological marker for dating deformation and magmatism

SWOT Analysis Applied to Wheat Straw Utilization as a Biofuel in Mexico

Wheat is one of the main crops worldwide with a production of 733 million of tons by 2015. By 2013, the wheat grain production in Mexico was 3,357,307 t. Wheat straw is generated as a biomass waste once the wheat is harvested. However, the agricultural biomass waste has acquired international relevance as a source of bioenergy. The utilization of bioenergy has significant environmental benefits, and also economic benefits because the biomass waste is valorized as biofuel. The use of wheat straw as raw material for any productive process presents diverse factors that must be considered. Among those factors are the low density of biomass, handling and high transportation cost, an attractive heating value, and the physicochemical characterization. Therefore, the aim of this work was to apply the SWOT analysis to wheat straw utilization as a biofuel in Mexico. The main findings highlighted an estimation of 4,612,950.23 t of wheat straw generated. The experimental results of proximate analysis were 64.42% volatile matter, 19.49% fixed carbon and 16.09% ash. The higher heating was 14.86 MJ/kg. An energy potential of 69 PJ per agricultural cycle was calculated, equivalent to 19% of the biomass energy share reported in Mexico’s National Energy Balance, by 2014

Wheat Straw Open Burning: Emissions and Impact on Climate Change

The state of Baja California, Mexico, is the second national wheat producer. Mexicali, the capital of Baja California, is the primary wheat producer, and it represents the most significant crop in the valley, with 90,609 ha of a cultivated surface by 2015; it leads to a wheat production of 585,334 t and a generation of 661,446 t of wheat straw as agricultural residue. The 15% of this waste has various uses. The 85% of wheat straw is open burnt in situ to prepare the farmland for the next agricultural cycle. Through the development of an emissions and energy model on iThink®, the emissions of 6,185 t of PM, 35,983 t of CO, and 1,125 t of CH4 considering a headfire burning or 3,373 t of PM, 30,360 t of CO, and 731 t of CH4 by backfire burning were estimated. Also, the wheat straw wasted energy was estimated at 8.15 PJ by 2015, with a lower heating value of 14.50 MJ/kg determined experimentally. The results highlight that for each hectare of harvested wheat, 6.205 t of wheat straw are generated and burnt. It represents the emission of pollutants and 89,972.50 MJ of wasted energy

Protective role of mindfulness, self-compassion and psychological flexibility on the burnout subtypes among psychology and nursing undergraduate students

Aims: To explore the relationship between mindfulness, self-compassion and psychological flexibility, and the burnout subtypes in university students of the Psychology and Nursing degrees, and to analyse possible risk factors for developing burnout among socio-demographic and studies-related characteristics. Design: Cross-sectional study conducted on a sample of 644 undergraduate students of Nursing and Psychology from two Spanish universities. Methods: The study was conducted between December 2015 and May 2016. Bivariate Pearson''s correlations were computed to analyse the association between mindfulness facets, self-compassion and psychological flexibility, and levels of burnout. Multivariate linear regression models and bivariate and multivariate binary logistic regressions were also computed. Results: The three subtypes of burnout presented significant correlations with psychological flexibility, self-compassion and some mindfulness facets. Psychological flexibility, self-compassion and the mindfulness facets of observing and acting with awareness were significantly associated to burnout. Among the risk factors, ‘year of study’ was the only variable to show significantly higher risk for every burnout subtype. Conclusion: The significant associations found between mindfulness, self-compassion, psychological flexibility and burnout levels underline the need of including these variables as therapeutic targets when addressing the burnout syndrome in university students. Impact. Undergraduate students, especially those of health sciences, often experience burnout. This study delves into the protective role of some psychological variables: mindfulness, self-compassion and psychological flexibility. These should be considered as potentially protective skills for developing burnout, and therefore, undergraduate students could be trained on these abilities to face their studies and their future profession to prevent experiencing burnout syndrome. © 2021 John Wiley & Sons Lt

IAA : Información y actualidad astronómica (44)

Sumario : La importancia de los cometas.-- Gamow, Alpher y el ylem.-- DECONSTRUCCIÓN Y otros ENSAYOS. El universo molecular.-- EL “MOBY DICK” DE... Alberto Molino (IAG).-- CIENCIA EN HISTORIAS...Tras la estela de Plateau.-- ACTUALIDAD.-- SALA LIMPIA.-- CIENCIA: PILARES E INCERTIDUMBRES. Explosiones de rayos gamma.N

Efecto de las fuentes de polen sobre el rendimiento en la extracción de aceite y perfil de ácidos grasos de las semillas de dátil (Phoenix dactylifera L.) cultivar Medjool de México

The present investigation aimed to assess the effect of pollen sources on the mass, dimension, oil content and fatty acid profile of the seeds from female palms of the Medjool date cultivar. The palms were pollinated with Deglet Noor, Khadrawy, Medjool and Zahidi cultivars. In addition, three palms were pollinated as the treatment control. The fatty acids were evaluated by gas chromatography-mass spectrometry. The surface morphology of date seed powder was examined using SEM, before and after n-hexane interaction. The seeds of the Medjool treatment had the greatest mass (1.42 g), but the lowest oil content (5.37% w/w); the control seeds showed smaller mass (1.21 g), but higher oil content (13.57% w/w). The proportion of fatty acids varied significantly among the treatments with respect to the control. The most abundant fatty acids were oleic (C18:1), lauric (C12:0), myristic (C14:0), palmitic (C16:0), linoleic (C18:2), and stearic (C18:0). Together these fatty acids presented a composition between 98.3 and 98.67% for treatments, and 99.0% for the control. The results indicate that the pollen sources from Deglet Noor, Khadrawy, Medjool and Zahidi cultivars had a significant effect on mass, dimension, oil content and fatty acid profile of the seeds of the date cultivar Medjool. The date seed oil could be used as edible oil, in food products, and in pharmaceutical and cosmetic applications.La presente investigación tuvo como objetivo evaluar el efecto de las fuentes de polen, sobre la masa, dimensión, contenido de aceite y el perfil de ácidos grasos de las semillas de dátil del cultivar Medjool. Las palmas hembras del cultivar Medjool fueron polinizadas con cultivares Deglet Noor, Khadrawy, Medjool y Zahidi. Además, tres palmas fueron polinizadas como tratamiento control. Los ácidos grasos se evaluaron por cromatografía de gases-espectrometría de masas. La morfología de la superficie del polvo de semillas de dátil se examinó utilizando un equipo SEM, antes y después de la interacción n-hexano. Las semillas del tratamiento Medjool resultaron con mayor masa (1,42 g), pero menor contenido de aceite (5,37% p/p); la semilla control, mostró una masa más pequeña (1,21 g), pero un mayor contenido de aceite (13,57% p/p). La composición de ácidos grasos varió significativamente entre los tratamientos con respecto al control. Los ácidos grasos mayoritarios fueron: oleico (C18:1), láurico (C12:0), mirístico (C14:0), palmítico (C16:0), linoleico (C18:2) and esteárico (C18:0). En total, estos ácidos grasos alcanzan una composición entre 98.3 y 98.67% para los tratamientos, y 99.0% para el control. Los resultados indican que la fuente de polen de los cultivares Deglet Noor, Khadrawy, Medjool y Zahidi tiene un efecto significativo sobre la masa, dimensión, contenido de aceite y el perfil de ácidos grasos de la semilla del cultivar de dátil Medjool. El aceite de la semilla de dátil, podría usarse como aceite comestible, productos alimenticios, aplicaciones farmacéuticas y cosméticas