Search results for "SCOPE"
showing 10 items of 2420 documents
Educación compensatoria : efectos recientes de un estudio clásico (High-Scope)
2014
Este artículo analiza dos estudios que prueban la tesis de que la educación de los desfavorecidos sociales en la edad temprana -3 y 4 años- merece la pena a corto y largo plazo. Para ello se analizan dos estudios preescolares complementarios –Perry y Curriculum -, de la Fundación High/Scope en los 60, evaluados en diversos momentos intermedios, el primero hasta alcanzar los 40 años y el segundo 23. Se describen los estudios y programas educativos, se analizan cuestiones metodológicas ligadas al seguimiento (muestra, validez, variables), se muestran los hallazgos, los tempranos específicamente escolares y otros de naturaleza distinta en la edad adulta. Finalmente se discute la modificabilida…
Chimney and Periscope Grafts Observed Over 2 Years After Their Use to Revascularize 169 Renovisceral Branches in 77 Patients With Complex Aortic Aneu…
2013
Purpose: To evaluate the performance of periscope and/or chimney grafts (CPGs) in the endovascular treatment of pararenal or thoracoabdominal aneurysms using off-the-shelf devices. Methods: Between February 2002 and August 2012, 77 consecutive patients (62 men; mean age 7369 years) suffering from pararenal aortic (n¼55), thoracoabdominal (n¼16), or arch to visceral artery aneurysms (n¼6) were treated with aortic stent-graft implantation requiring chimney and/or periscope grafts to maintain side branch perfusion. CPGs were planned in advance and were not used as bailout. A standardized follow-up protocol including computed tomographic angiography, laboratory testing, and clinical examination…
FIB-FESEM and EMPA results on Antoninianus silver coins for manufacturing and corrosion processes
2018
[EN] A set of ancient Antoninianus silver coins, dating back between 249 and 274¿A.D. and minted in Rome, Galliae, Orient and Ticinum, have been characterized. We use, for the first time, a combination of nano-invasive (focused ion beam-field emission scanning electron microscopy-X-ray microanalysis (FIB-FESEM-EDX), voltammetry of microparticles (VIMP)) and destructive techniques (scanning electron microscopy (SEM-EDX) and electron microprobe analysis (EMPA)) along with non-invasive, i.e., micro-Raman spectroscopy. The results revealed that, contrary to the extended belief, a complex Ag-Cu-Pb-Sn alloy was used. The use of alloys was common in the flourishing years of the Roman Empire. In th…
Mēdlera teleskopa fotogrāfija tomēr eksistē!
2020
Agrāk domāja, ka Latvijas Universitātes Astronomiskā torņa pirmā teleskopa fotogrāfija nav saglabājusies. Veicot rūpīgus meklējumus Latvijas Universitātes Muzejā, tika atrasta vienīgā teleskopa fotogrāfija. Video paskaidro, kā tā tika atrasta.
Search for cosmic sources in neutrino telescopes and time calibration in the ANTARES neutrino telescope
2018
Aunque la astronomía de neutrinos es una disciplina muy reciente, está resultando ser muy en un estado estimulante. Los diversos resultados publicados por la colaboración IceCube han mostrado la existencia de un flujo de neutrinos cósmicos de altas energías, del cual se desconoce su origen, y del que no se ha observado una dirección privilegiada. El telescopio de neutrinos ANTARES ha sido capaz de excluir la posibilidad de que algunos de los eventos observados por IceCube se hayan producido por una fuente puntual en la región del centro galáctico. Además, el último análisis de flujos difusos de ANTARES muestra un resultado compatible con el flujo observado por IceCube. Actualmente, existen …
Changes in surface stress, morphology and chemical composition of silica and silicon nitride surfaces during the etching by gaseous HF acid
2007
International audience; HF acid attack of SiO2 and Si3N4 substrates is analyzed to improve the sensitivity of a sensor based on inicrocantilever. Ex situ analysis of the etching using XPS, SIMS and AFM show significant changes in the anisotropy and the rate of the etching of the oxides on SiO2 and Si3N4 surface. Those differences influence the kinetic evolution of the plastic bending deflection of the cantilever coated with SiO2 and Si3N4 layer, respectively. The linear dependence between the HF concentration and the Si3N4 cantilever bending corresponds to a deep attack of the layer whereas the nonlinear behavior observed for SiO2 layer can be explained by a combination of deep and lateral …
Detecting the stimulated decay of axions at radio frequencies
2018
Assuming axion-like particles account for the entirety of the dark matter in the Universe, we study the possibility of detecting their decay into photons at radio frequencies. We discuss different astrophysical targets, such as dwarf spheroidal galaxies, the Galactic Center and halo, and galaxy clusters. The presence of an ambient radiation field leads to a stimulated enhancement of the decay rate; depending on the environment and the mass of the axion, the effect of stimulated emission may amplify the photon flux by serval orders of magnitude. For axion-photon couplings allowed by astrophysical and laboratory constraints(and possibly favored by stellar cooling), we find the signal to be wi…
Energy conversion efficiency in betavoltaic cells based on the diamond Schottky diode with a thin drift layer
2020
The HPHT diamond Schottky diode was assembled as a Metal/Intrinsic/p-doped structure betavoltaic cell (BC) with a very thin (1 μm) drift layer and tested under 5–30 keV electron beam irradiation using a scanning electron microscope (SEM). The effect of the β-radiation energy and the backscattering of electrons on the energy conversion was studied. From the results obtained, it is shown that, the efficiency of the investigated BC increases from 1.01 to 3.75% with the decrease of β-particle energy from 30 to 5 keV due to an increase of the electron beam absorption in a thin drift layer. Maximum efficiency is achieved when the electron beam energy is close to the average β-decay energy of 3H. …
New Polylactic Acid Composites Reinforced with Artichoke Fibers
2015
In this work, artichoke fibers were used for the first time to prepare poly(lactic acid) (PLA)-based biocomposites. In particular, two PLA/artichoke composites with the same fiber loading (10% w/w) were prepared by the film-stacking method: the first one (UNID) reinforced with unidirectional long artichoke fibers, the second one (RANDOM) reinforced by randomly-oriented long artichoke fibers. Both composites were mechanically characterized in tensile mode by quasi-static and dynamic mechanical tests. The morphology of the fracture surfaces was analyzed through scanning electron microscopy (SEM). Moreover, a theoretical model, i.e., Hill's method, was used to fit the experimental Young's modu…
Follicle Cells of Styela plicata Eggs (Ascidiacea)
2001
Styela plicata eggs are surrounded by large follicle cells that at LM appear as highly vacuolated and columnar in shape; at the apical end of each cell lies a very large and clear vacuole, half of which extends inward. Electron microscope observations show a Single layer of largely spaced box-like follicle cells; the close cell-cell contact at their base is realized by interdigitations. The cell surface shows a peculiar structure, more developed in the latero-basal regions, consisting of a complex of membrane extensions, i.e. microvilli, filopodia and lamellipodia. Filopodia irradiate in all directions towards the adjacent cells and the outermost vitelline coat, thus creating a complex netw…