Este artículo describe un uso particular de marcación de foco en español, construido con el relativo lo que y el verbo ser en dos variantes: lo que es y lo que viene siendo. Con el análisis de 106 ...ejemplos obtenidos del Corpus michoacano del español, se explica cómo esta construcción, derivada de las perífrasis de relativo, se convierte en un focalizador dentro de una estructura monoclausal. Su uso se encontró fundamentalmente en situaciones de comunicación dialógica oral en el ámbito público, con un grado de formalidad intermedio; no así en situaciones completamente coloquiales ni en situaciones de alta formalidad.
This paper describes the use of a special focus marker in Spanish, constructed with the relative lo que and the verb ser in two variants: lo que es and lo que viene siendo. With 106 examples obtained from the Corpus michoacano del español, the paper explains how this construction, deriving from cleft sentences, becomes a focus marker within a monoclausal structure. This usage is mainly attested in oral dialogical discourse in the public sphere, where there is a medium level of formality; it is not in colloquial discourse, nor in highly formal situations.
Se presenta una propuesta de proyecto de bajo costo para que alumnos de temprana edad se motiven por el estudio de la física en el área de la electricidad, los circuitos eléctricos y la programación ...de microcontroladores a través de la integración de elementos de bajo costo para animar visualmente prendas textiles y artículos de uso cotidiano. Durante el desarrollo del proyecto se parte desde el uso de los conceptos de la ley de Ohm y el estrecho vínculo que existe entre la representación de un número binario en el lenguaje Arduino hasta salida de voltaje del microcontrolador para encender o apagar cada uno de los ledes que se programan de manera secuencial. A project for early age students is proposed in order to motivate the study of physics, mainly for the electricity area, electrical circuits and microcontroller programming through the integration of low-cost elements to animate visually textiles and common daily items. It includes the use of the concepts related to the Ohm law and the link that exists between the representation of a binary number in the Arduino language with the physical voltage output of the microcontroller to turn on or off each one of the led as result of a programming sequence. PACS: Laboratory computer use (uso de computadoras de laboratorio), 01.50.Le; Demonstration experiments and apparatus (experimentos demostrativos y aparatos), 01.50.My; Laboratory experiments and apparatus (experimentos de laboratorio y aparatos), 01.50.Pa
Durante las últimas décadas, el mundo se ha expuesto a una serie de amenazas por brotes virales emergentes de diferente índole, los cuales, sólo al estudiarlos en detalle, surge la posibilidad
de ...comprender su verdadero impacto, no sólo de forma inmediata, si no también, a largo plazo.
Recientemente, el 12 de diciembre de 2019, la Comisión Municipal de Salud de Wuhan, en la República Popular de China, hizo público un reporte de 27 casos humanos quienes cursaron con una neumonía viral, de los cuales 7 pacientes se encontraban en condiciones críticas, la cual tenía como etiología un nuevo patógeno humano con alta capacidad zoonótica, conocido provisionalmente como Coronavirus novel 2019 (2019-nCoV), y unas semanas después como Enfermedad por Coronavirus 2019 (COVID-19) causada por el virus SARS-CoV-2.
Two novel styrene-containing meta-carborane derivatives substituted at the second carbon cluster atom (C
) with either a methyl (Me) or a phenyl (Ph) group are introduced herein along with a new set ...of stilbene-containing ortho- (o-) and meta- (m-) carborane dyads. The latter set of compounds have been prepared from styrene-containing carborane derivatives via a Heck coupling reaction. High regioselectivity has been achieved for these compounds by using a combination of palladium complexes Pd
(dba)
/Pd(t-Bu
P)
as a catalytic system, yielding exclusively E isomers. All compounds have been fully characterised and the crystal structures of seven of them were analysed by X-ray diffraction. The absorption spectra of these compounds are similar to those of their respective fluorophore groups (styrene or stilbene), showing a very small influence of the substituent (Me or Ph) linked to the second C
atom or the cluster isomer (o- or m-). On the other hand, fluorescence spectroscopy revealed high emission intensities for Me-o-carborane derivatives, whereas their Ph-o-carborane analogues evidenced an almost total lack of fluorescence, confirming the significant role of the substituent bound to the adjacent C
in o-carboranes. In contrast, all the m-carborane derivatives display similar photoluminescence (PL) behavior regardless of the substituent attached to the second C
, demonstrating its small influence on emission properties. Additionally, m-carborane derivatives are significantly more fluorescent than their o-counterparts, reaching quantum yield values as high as 30.2%. Regarding solid state emission, only stilbene-containing Ph-o-carborane derivatives, which showed very low fluorescence in solution, exhibited notable PL emission in films attributed to aggregation-induced emission. DFT calculations were performed to successfully complement the photoluminescence studies, supporting the experimentally observed photophysical behavior of the styrene and stilbene-containing carborane derivatives. In conclusion, in this work it is proved that it is possible to tailor the PL properties of carborane-stilbene dyads by changing the C
substituent and the carborane isomer.
Resumen Introducción y Objetivos La creciente población anciana y el uso amplio de la endoscopia por cápsula han llevado a una cantidad mayor de procedimientos en aquellos pacientes. El objetivo del ...presente estudio fue valorar la utilidad de la endoscopia por cápsula en pacientes mayores. Materiales y Métodos Se clasificó a todos los pacientes consecutivos en nuestro centro sometidos a cápsula endoscópica (CE) dentro del periodo de tiempo 2004-2016 como mayores (≥75 años) y más jóvenes. Los hallazgos y el rendimiento de diagnóstico se valoraron comparativamente. Resultados De 2,311 pacientes (edad promedio: 59.5 ± 19.23 años, 44.48% hombres), 648 se encontraban en el grupo de mayores y 1,663 en el grupo de más jóvenes. El tiempo de tránsito gástrico fue más corto en los pacientes mayores ( p=0.001 ), mientras que el tiempo de tránsito del intestino delgado fue más corto en el grupo de pacientes más jóvenes ( p<0.001 ). El rendimiento de diagnóstico global fue más alto en los ancianos (50.66% vs . 41.19%, p<0.001 ). El sangrado gastrointestinal de origen oscuro fue la indicación más frecuente para la endoscopia por cápsula en los ancianos (90.4% vs. 53.77%, p<0.001 ), logrando un rendimiento de diagnóstico más alto que en la población más joven (51.47% vs. 42.76%, p=0.002 ), mientras que la enfermedad de Crohn, sospecha o conocimiento de neoplasmas/pólipos, síndrome de malabsorción, y dolor abdominal fueron las indicaciones en el grupo de pacientes más jovenes. Tales indicaciones fueron poco comunes en el grupo de mayores. Se diagnosticó con mayor frecuencia las lesiones vasculares y el sangrado activo en los pacientes mayores, mientras que las úlceras/erosiones y la atrofia muscular fueron más comúnes en los pacientes más jóvenes ( p<0.001 ). Conclusiones La endoscopia por cápsula logró un rendimiento de diagnóstico global más alto en los pacientes ancianos. La indicación de sangrado gastrointestinal de origen oscuro para endoscopia por cápsula fue mucho más frecuente en el grupo de edad avanzada y presentó un rendimiento de diagnóstico mayor.
Polylactic acid (PLA)-based products can be found in a wide range of industrial applications due to their favorable performances. Unfortunately, neat PLA also exhibits some limitations which could be ...overcome by blending, composites or self-reinforced compounding. On the other hand, the mechanical characterization of PLA during in vitro degradation process has been generally limited to some basic mechanical tests which can be improved by the application of fracture mechanics analysis. The PLA matrix was reinforced (2.5 to 20 wt.%) with hydroxyapatite (HA) and processed as film or fiber in order to be experimentally evaluated. The evolution of mechanical performance during in vitro degradation was characterized by stress-based analysis and fracture mechanics. The composites displayed similar particle size distributions and more frequent agglomeration at large filler content. The film with 2.5% HA showed an enhanced crack resistance followed by a drastic drop at shorter immersion times linked to a premature matrix degradation. Fibers displayed higher tensile performance, compared to films, and faster degradation in accordance with thinner cross section. The performed characterizations indicated hydrolysis of PLA controlled by autocatalytic random scission and marginal end scission. Experimental behavior also showed an energy–stress transition, with the filler volume fraction, to define the most sensitive mechanical parameter. The whole performance during in vitro degradation can be described by three stages: (i) running-in, (ii) steady and (iii) severe. Particularly, the combination of composition, compounding method and evaluated mechanical parameter defines the presence or not of these three different stages along the in vitro degradation process.
Graphical Abstract
En el marco teórico de la β-convergencia, este trabajo investiga el proceso de convergencia regional entre los estados mexicanos más y menos expuestos a la globalización. El método aplica mínimos ...cuadrados ponderados y pruebas anidadas para hacer comparaciones interregionales. Después de controlar por diferencias en el estado estacionario, se encuentra convergencia regional a tasas entre 1.2% y 4.6% durante 1940-2015. En la etapa abierta, la velocidad de convergencia se elevó entre los estados más expuestos a la globalización, pero se frenó entre los menos expuestos. Además, avances en educación y salud han sido determinantes para el crecimiento regional.
ABSTRACT
We present here the second part of a project that aims at solving the controversy regarding the issue of the bar effect on the radial distribution of metals in the gas-phase of spiral ...galaxies. In Paper I, we presented a compilation of more than 2800 H ii regions belonging to 51 nearby galaxies for which we derived chemical abundances and radial abundance profiles from a homogeneous methodology. In this paper, we analyse the derived gas-phase radial abundance profiles of 12+log (O/H) and log (N/O), for barred and unbarred galaxies separately, and find that the differences in slope between barred and unbarred galaxies depend on galaxy luminosity. This is due to a different dependence of the abundance gradients (in dex kpc−1) on luminosity for the two types of galaxies: in the galaxy sample under consideration the gradients appear to be considerably shallower for strongly barred galaxies in the whole luminosity range, while profile slopes for unbarred galaxies become steeper with decreasing luminosity. Therefore, we only detect differences in slope for the lower luminosity (lower mass) galaxies (MB ≳ −19.5 or M* ≲ 1010.4 M⊙). We discuss the results in terms of the disc evolution and radial mixing induced by bars and spiral arms. Our results reconcile previous discrepant findings that were biased by the luminosity (mass) distribution of the sample galaxies and possibly by the abundance diagnostics employed.
We report on anomalously long duration (2 ms) count rate bursts following the impact of cosmic ray showers near a 7.62 cm x⊘7.62 cm LaBr3 scintillation detector at the High Altitude Water Cherenkov ...array in Mexico, previously described by Stenkin et al. (2001), and termed “neutron bursts.” The largest burst produced 198 counts within 2 ms in our LaBr3 detector. We simulate the neutron burst albedo flux (that is, secondary emissions from an extensive air shower core impacting the ground), and show that (1) the characteristic spectra and count rates are well explained by neutron absorption in the ground and (2) any cosmic ray secondary that produces neutrons, either through hadron inelastic collisions, or photoneutron production by gamma‐rays, produces the same characteristic spectra. This implies that other natural phenomena that produce downward beams of gamma‐rays, like Terrestrial gamma ray flashes, should produce a similar “neutron burst” signature from the photoneutron reactions occurring in the soil.
Plain Language Summary
When very large cosmic ray showers (CRS) impact the ground, neutrons are produced in the soil that will rattle around until they become captured by soil particles and release energetic gamma‐rays. This produces a slow explosion of particles emanating from the ground following a CRS impact, and is termed a 'neutron burst'. We present recent observations of neutron bursts from a hand held sized gamma‐ray detector at the High Altitude Water Cherenkov (HAWC) array in Mexico, that exhibit interesting spectral features (the presence of positron annihilation), and an interesting time structure (hundreds of counts within a few ms). Our simulations indicate that Terrestrial gamma‐ray flashes (TGFs, bursts of gamma‐rays associated with lightning) should also produce these neutron bursts. An implication of this work is that existing deployments of ground based TGF instruments, comprised of small gamma‐ray detectors, can additionally be used to observe signatures of large cosmic ray showers on clear days.
Key Points
We report on fairweather count rate bursts with 2 ms duration following the impact of a large cosmic ray shower near a small scintillation detector at HAWC
Simulations show that the spectra and decay time can be produced by either hadronic interactions, or photoneutron reactions from gamma‐rays
These results imply that downward TGFs could produce a similar delayed neutron signature in the soil near ground based detectors
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