3,547 research outputs found
Shedding light on the taxonomic diversity of the south american miocene caimans: the status of Melanosuchus fisheri (Crocodylia, Alligatoroidea)
Melanosuchus niger Spix is distributed throughout the Amazon River basin today. The extinct Melanosuchus fisheri Medina from the late Miocene of Venezuela was erected based on two almost complete, but heavily deformed skulls (the holotype MCNC 243 and the referred specimen MCZ 4336), which show morphological differences from each other. The comparison indicates that only the holotype can be referred to Melanosuchus Gray. We propose MCZ 4336 is a representative of the caimanine Globidentosuchus brachyrostris Scheyer, Aguilera, Delfino, Fortier, Carlini, Sánchez, Carrillo-Briceño, Quiroz and Sãnchez-Villagra. Although the taxonomy of M. fisheri is taken into question herein, the classification of the holotype still sustains the hypothesis that the genus is registered in South America since the late Miocene
Tuning the carrier injection barrier of hybrid metal–organic interfaces on rare earth-gold surface compounds
Magnetic hybrid metal-organic interfaces possess a great potential in areas such as organic spintronics and quantum information processing. However, tuning their carrier injection barriers on-demand is fundamental for the implementation in technological devices. We have prepared hybrid metal-organic interfaces by the adsorption of copper phthalocyanine CuPc on REAu2 surfaces (RE = Gd, Ho and Yb) and studied their growth, electrostatics and electronic structure. CuPc exhibits a long-range commensurability and a vacuum level pinning of the molecular energy levels. We observe a significant effect of the RE valence of the substrate on the carrier injection barrier of the hybrid metal-organic interface. CuPc adsorbed on trivalent RE-based surfaces (HoAu2 and GdAu2) exhibits molecular level energies that may allow injection carriers significantly closer to an ambipolar injection behavior than in the divalent case (YbAu2)
Relationship between solar radiation on watercore on apple fruit assessed with MRI
This work is a preliminary studio of the possibility of assess a relationship between solar radiation and watercore development on apple fruit, during maturation, using a non destructive method such as Magnetic Resonance Imaging (MRI). For such purpose, several low cost solar radiation sensors were designed for the trial and placed at 2 different heights (1.5 and 2.5 m) on 6 adult ?Esperiega? apple trees, in a commercial orchard in Ademuz (Valencia). Sensors were connected along 27 days, during the end of the growth period and start of the fruit maturation process, and radiation measurements of the a-Si sensors were recorded every 1 minute. At the end of this period, fruits from the upper and the lower part of the canopy of each tree were harvested. In all, 152 apples were collected and images with MRI. A Principal Component Analysis, perfomed over the histograms of the images, as well as segmentation methods were performed on the MR images in order to find a pattern involving solar radiation and watercore incidence
Assessment of watercore development in apples with MRI: Effect offruit location in the canopy
tWatercore distribution inside apple fruit (block or radial), and its incidence (% of tissue) were relatedto the effect of solar radiation inside the canopy as measured by a set of low-cost irradiation sensors.221 samples were harvested in two seasons from the top and the bottom of the canopy and submittedto the non-invasive and non-destructive technique of magnetic resonance imaging (MRI) in order toobtain 20 inner tomography slices from each fruit and analyze the damaged areas using an interactive3D segmentation method. The number of fruit corresponding to each type of damage and the relevantpercentage were calculated and it was found that apples from the top of the tree were mainly of the radialtype (84%) and had more watercore (approx. 5% more) than apples from the bottom (65% radial). From theimage segmentation, the Euler number, a morphometric parameter, was extracted from the segmentedimages and related to the type of watercore symptoms. Apples with block watercore were grouped inEuler numbers between −400 and 400 with a small evolution. For apples with radial development, theEuler number was highly negative: up to −1439. Significant differences were also found regarding sugarcomposition, with higher fructose and total sugar contents in apples from the upper canopy, compared tothose in the lower canopy location. In the seasons studied (2011 and 2012), significantly higher sorbitoland lower sucrose and fructose contents were found in watercore-affected tissue compared to the healthytissue of affected apples and also compared to healthy apples
The yield of air fluorescence induced by electrons
The fluorescence yield for dry air and pure nitrogen excited by electrons is
calculated using a combination of well-established molecular properties and
experimental data of the involved cross sections. Particular attention has been
paid to the role of secondary electrons from ionization processes. At high
pressure and high energy, observed fluorescence turns out to be proportional to
the ionization cross section which follows the Born-Bethe law. Predictions on
fluorescence yields in a very wide interval of electron energies (eV - GeV) and
pressures (1 and 1013 hPa) as expected from laboratory measurements are
presented. Experimental results at energies over 1 MeV are in very good
agreement with our calculations for pure nitrogen while discrepancies of about
20% are found for dry air, very likely associated to uncertainties in the
available data on quenching cross sections. The relationship between
fluorescence emission, stopping power and deposited energy is discussed.Comment: 27 pages, 12 figures, 64 references. Accepted in Astroparticle
Physic
Epidemiología de las fracturas de la extremidad proximal del fémur en asturias
Hemos realizado un estudio epidemiológico de las fracturas de fémur proximal
en personas mayores de 50 años, atendidas en nuestro Hospital durante los años 1990-92.
Se valoraron un total de 355 casos. En el período estudiado se observó que las fracturas más
numerosas fueron la cervicales, no encontrando diferencias significativas en los ingresos según
el período estacional. La edad media de presentación fue de 81 años. La tasa de incidencia
fue muy semejante a las otras provincias españolas y menor que la encontrada en los países
del Norte de Europa, Inglaterra y Estados Unidos.We have performed an epidemiologic study on the incidence of proximal femoral
fractures in patients older than 50 years, all reviewed in our Hospital from 1990 to 1992.
We included 355 patients. Femoral neek fractures were the most frequent lesions. No significant
differences in the hospital admissions were found during all the year's seasons. The mean
age of presentation was 81 years. The incidence rate was similar to the rest of Spain, and less
than in North Europe, England and United States
Dimensiones Pedagógicas del Laboratorio de Tizas de Jorge Oteiza
Dimensiones Pedagógicas del Laboratorio de Tizas de Jorge Oteiz
- …