2,598 research outputs found
Evaluation of Skylab EREP data for land resource management
There are no author-identified significant results in this report
Band gap bowing in NixMg1-xO.
Epitaxial transparent oxide NixMg1-xO (0 ≤ x ≤ 1) thin films were grown on MgO(100) substrates by pulsed laser deposition. High-resolution synchrotron X-ray diffraction and high-resolution transmission electron microscopy analysis indicate that the thin films are compositionally and structurally homogeneous, forming a completely miscible solid solution. Nevertheless, the composition dependence of the NixMg1-xO optical band gap shows a strong non-parabolic bowing with a discontinuity at dilute NiO concentrations of x 0.074 and account for the anomalously large band gap narrowing in the NixMg1-xO solid solution system
Radon measurements in underground workplaces in the Campus of the University of Alicante
Las medidas del gas radiactivo radón en lugares de trabajo subterráneos del Campus de la Universidad de Alicante fueron realizadas mediante dispositivos E-PERM® de corto plazo durante el invierno de 2010 y el verano de 2011. Las concentraciones de radón obtenidas muestran valores máximos de 73,8 Bq/m3 en invierno y 84,0 Bq/m3 en verano, así como una media aritmética de 30,3 Bq/m3. Aunque no se abordan concentraciones medias anuales, todos los resultados se encuentran por debajo de los valores recogidos en la Recomendación 90/143/EURATOM de la Comisión Europea relativa a la protección de la población contra los peligros de una exposición al radón en el interior de edificios así como los establecidos por la Instrucción IS-33 del Consejo de Seguridad Nuclear en lugares de trabajo, contribuyendo a la evaluación de la distribución de radón a nivel nacional y prestando atención a los problemas que este gas puede ocasionar en espacios subterráneos.Measurements of radioactive radon gas in underground workplaces in the Campus of the University of Alicante were performed using short period E-PERM® devices during the winter of 2010 and summer of 2011. The obtained radon concentrations show maximum values of 73.8 Bq/m3 in winter and 84.0 Bq/m3 in summer, and an arithmetic mean of 30.3 Bq/m3. Despite not considering annual mean concentrations, results are below those included in 90/143/Euratom European Commission Recommendation on the protection of the public against the dangers of radon exposure inside buildings, as well as those established by the Nuclear Security Council IS-33 Instruction in workplaces, contributing to the evaluation of the national distribution of radon and paying attention to radon problems in underground spaces.El presente trabajo ha sido elaborado bajo la concesión a su autora de una Ayuda de Posgrado para la Formación de Profesorado Universitario (FPU) del Programa Nacional de Formación de Recursos Humanos de Investigación, (referencia AP2010-2272) y es parte del Proyecto “Desarrollo y Validación de una Metodología de Clase Mundial para la Evaluación e Intercomparación del Nivel de Sostenibilidad en la Edificación” (referencia IPT-380000-2010-16), del Plan Nacional del I+D+I del Ministerio de Ciencia Innovación, financiado con fondos FEDER
Spatially resolved spectroscopy of the globular cluster RZ 2109 and the nature of its black hole
We present optical HST/STIS spectroscopy of RZ 2109, a globular cluster in
the elliptical galaxy NGC 4472. This globular cluster is notable for hosting an
ultraluminous X-ray source as well as associated strong and broad [OIII] 4959,
5007 emission. We show that the HST/STIS spectroscopy spatially resolves the
[OIII] emission in RZ 2109. While we are unable to make a precise determination
of the morphology of the emission line nebula, the best fitting models all
require that the [OIII] 5007 emission has a half light radius in the range 3-7
pc. The extended nature of the [OIII] 5007 emission is inconsistent with
published models that invoke an intermediate mass black hole origin. It is also
inconsistent with the ionization of ejecta from a nova in the cluster. The
spatial scale of the nebula could be produced via the photoionization of a
strong wind driven from a stellar mass black hole accreting at roughly its
Eddington rate.Comment: 7 pages, 4 figures - accepted for publication in Ap
Oblique Propagation and Refraction of Gravity Waves Over the Andes Observed by GLORIA and ALIMA During the SouthTRAC Campaign
Gravity waves (GW) carry energy and momentum from the troposphere to the middle atmosphere and have a strong influence on the circulation there. Global atmospheric models cannot fully resolve GWs, and therefore rely on highly simplified GW parametrizations that, among other limitations, account for vertical wave propagation only and neglect refraction. This is a major source of uncertainty in models, and leads to well-known problems, such as the late break-up of polar vortex due to the “missing” GW drag around 60°S. To investigate these phenomena, GW observations over Southern Andes were performed during SouthTRAC aircraft campaign. This paper presents measurements from a SouthTRAC flight on 21 September 2019, including 3-D tomographic temperature data of the infrared limb imager GLORIA (8–15 km altitude) and temperature profiles of the ALIMA lidar (20–80 km altitude). GLORIA observations revealed multiple overlapping waves of different wavelengths. 3-D wave vectors were determined from the GLORIA data and used to initialize a GW ray-tracer. The ray-traced GW parameters were compared with ALIMA observations, showing good agreement between the instruments and direct evidence of oblique (partly meridional) GW propagation. ALIMA data analysis confirmed that most waves at 25–40 km altitudes were indeed orographic GWs, including waves seemingly upstream of the Andes. We directly observed horizontal GW refraction, which has not been achieved before SouthTRAC. Refraction and oblique propagation caused significant meridional transport of horizontal momentum as well as horizontal momentum exchange between waves and the background flow all along the wave paths, not just in wave excitation and breaking regions
Variation in Sex Allocation and Floral Morphology in an Expanding Distylous Plant Hybrid Complex
Premise of research. Sex allocation, the relative energy devoted to producing pollen, ovules, and floral displays, can significantly affect reproductive output and population dynamics. In this study, we investigated floral morphology and gamete production in bisexual, distylous plants from a self-incompatible hybrid complex (Piriqueta cistoides ssp. caroliniana Walter [Arbo]; Turneraceae). Sampling focused on two parent types (C, V) and their stable hybrid derivative (H). Since H morphotypes are heterotic for growth and fruit production, we hypothesized that they would produce larger flowers with more gametes. We also anticipated that plants with long styles (long morphs) would produce less pollen than short morphs, since long-morph pollen is larger.
Methodology. Over two consecutive summers, flowers were collected from 1465 individual plants in 28 field populations. Floral parameters were measured digitally, and each flower’s pollen number, ovule number, and stigma-anther separation was quantified under a dissecting microscope. Gamete production (n = 332) and stigma-anther separation (n = 119) were also quantified for plants from a greenhouse accession.
Pivotal results. Floral display differed among morphotypes, with H plants producing the largest flowers and C plants displaying the least petal separation. Hybrid morphotypes produced significantly more pollen than parental morphotypes, and pollen quantity was significantly greater for long morphs. Ovule production, however, was greatest for V flowers. Stigma-anther separation differed between years and style morphs (greater for short morphs) but not among morphotypes or within a single season.
Conclusions. Differences in pollen production between morphs were not consistent with trade-offs in pollen size and number or selection for increased male function in short morphs. Greater stigma-anther separation in short morphs supported the hypothesis of selection to reduce pollen interference. Enhanced floral display and pollen production followed other heterotic traits observed in H morphotypes. The superior ability of H morphotypes to attract pollinators and sire seeds might partially explain this hybrid zone’s continuing expansion
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