3,845 research outputs found
Análisis de la melodía: oraciones simples vs. compuestas
El objetivo de la investigación que aquí se presenta es comparar la melodía (Frecuencia Fundamental o F0) de un conjunto de oraciones simples (de conclusión y de no conclusión), coordinadas (copulativas y adversativas) y subordinadas (condicionales con si y causales con porque) delimitadas a partir de textos orales, elegidos al azar, emitidos en un estilo semiespontáneo por 43 informantes con un nivel de instrucción medio-alto o alto de las capitales de las Islas Canarias. Nuestro interés se ha centrado en la inflexión final (tonema) y en la dirección de la F0 en tres líneas de declinación trazadas a partir del punto de partida y el punto de llegada de las curvas de F0 (D1) y de los picos de altura tonal: la línea de altura tonal (D2) y la de los valles tonales (D3). El análisis acústico se efectuó con el CSL 4300 de Kay Elemetric Co.The aim of the following research is to compare the melody (the Fundamental Frequency or F0) in a set of simple conclusion and no conclusion sentences, of compound copulative and adversative clauses and of conditional and causal subordinated clauses. These sentences have been chosen at random and taken from semispontaneus speech by 43 middle-high or high level informants, from the very principal cities of the Canary Islands. Our interest has centred on the final inflexion tonema) and the direction of the F0 on three declination lines planned from the initial point to the arrival one of the F0 curves (D1), and from the Turning points: the Topline (D2) and the Baseline or Bottom line (D3). The acoustic analysis was carried out with the CSL 4300 of Kay Elemetric Co.El objetivo de la investigación que aquí se presenta es comparar la melodía (Frecuencia Fundamental o F0) de un conjunto de oraciones simples (de conclusión y de no conclusión), coordinadas (copulativas y adversativas) y subordinadas (condicionales con si y causales con porque) delimitadas a partir de textos orales, elegidos al azar, emitidos en un estilo semiespontáneo por 43 informantes con un nivel de instrucción medio-alto o alto de las capitales de las Islas Canarias. Nuestro interés se ha centrado en la inflexión final (tonema) y en la dirección de la F0 en tres líneas de declinación trazadas a partir del punto de partida y el punto de llegada de las curvas de F0 (D1) y de los picos de altura tonal: la línea de altura tonal (D2) y la de los valles tonales (D3). El análisis acústico se efectuó con el CSL 4300 de Kay Elemetric Co
Crystal defects and spin tunneling in single crystals of Mn12 clusters
The question addressed in this paper is that of the influence of the density of dislocations on the spin tunneling in Mn12 clusters. We have determined the variation in the mosaicity of fresh and thermally treated single crystals of Mn12 by analyzing the widening of low angle x-ray diffraction peaks. It has also been well established from both isothermal magnetization and relaxation experiments that there is a broad distribution of tunneling rates which is shifted to higher rates when the density of dislocations increases
Necrobiosis lipoidica developing within a surgical scar in a non-diabetic patient: Type III Koebner phenomenon (isomorphic response), Wolf's isotopic response or Ruocco's immunocompromised cutaneous district?
Sir, Necrobiosis lipoidica is a chronic granulomatous disease typically associated with diabetes mellitus. We report a case of necrobiosis lipoidica occurring in a surgical scar in a non-diabetic patient. We found only nine previous reports of necrobiosis lipoidica appearing after trauma or in surgical scars, as a manifestation of Type III Koebner phenomenon. Most of these were in diabetic patients..
Plasticity of Dendritic Spines. Not Only for Cognitive Processes
Excitatory synaptic transmission is associated with the input of “new” information at synaptic junctions established by dendritic spines. The role that each type of spine plays in the transmission of the synaptic impulses is different. Indeed, there is a close relationship between the shape of spines and the differential processing of the excitatory synaptic information that is relayed to them, influencing in turn the transmission of synaptic information related to several psychoneural processes
Pre-main sequence stars in the Lagoon Nebula (M8)
We report the discovery of new pre-main sequence (PMS) stars in the Lagoon
Nebula (M8) at a distance of 1.25 kpc, based on intermediate resolution spectra
obtained with the Boller & Chivens spectrograph at the 6.5-m Magellan I
telescope (Las Campanas Observatory, Chile). According to the spectral types,
the presence of emission lines and the lithium 6708A absorption line, we are
able to identify 27 classical T Tauri stars, 7 weak-lined T Tauri stars and 3
PMS emission objects with spectral type G, which we include in a separated
stellar class denominated "PMS Fe/Ge class". Using near-infrared photometry
either from 2MASS or from our own previous work we derive effective
temperatures and luminosities for these stars and locate them in the
Hertzsprung-Russell diagram, in order to estimate their masses and ages. We
find that almost all of our sample stars are younger than 3 10^6 years and span
over a range of masses between 0.8 and 2.5 Msun. A cross-correlation between
our spectroscopic data and the X-ray sources detected with the Chandra ACIS
instrument is also presented.Comment: 18 pages, 15 figures, MNRAS, in pres
A multi-wavelength view of the central kiloparsec region in the Luminous Infrared Galaxy NGC1614
The Luminous Infrared Galaxy NGC1614 hosts a prominent circumnuclear ring of
star formation. However, the nature of the dominant emitting mechanism in its
central ~100 pc is still under debate. We present sub-arcsecond angular
resolution radio, mid-infrared, Pa-alpha, optical, and X-ray observations of
NGC1614, aimed at studying in detail both the circumnuclear ring and the
nuclear region. The 8.4 GHz continuum emission traced by the Very Large Array
(VLA) and the Gemini/T-ReCS 8.7 micron emission, as well as the Pa-alpha line
emission, show remarkable morphological similarities within the star-forming
ring, suggesting that the underlying emission mechanisms are tightly related.
We used an HST/NICMOS Pa-alpha map of similar resolution to our radio maps to
disentangle the thermal free-free and non-thermal synchrotron radio emission,
from which we obtained the intrinsic synchrotron power-law for each individual
region within the central kpc of NGC1614. The radio ring surrounds a relatively
faint, steep-spectrum source at the very center of the galaxy, suggesting that
the central source is not powered by an AGN, but rather by a compact (r < 90
pc) starburst. Chandra X-ray data also show that the central kpc region is
dominated by starburst activity, without requiring the existence of an AGN. We
also used publicly available infrared data to model-fit the spectral energy
distribution of both the starburst ring and a putative AGN in NGC1614. In
summary, we conclude that there is no need to invoke an AGN to explain the
observed bolometric properties of the galaxy.Comment: 13 pages, 7 figures, 5 tables. Accepted for publication in Ap
Finishing lambs using an integral feed under a restricted-feeding program in an intensive production system in Northern Mexico
The objective of this study was to compare the productive performance of finishing lambs using an integral diet under a restricted-feeding program. Ten Dorper lambs were assigned to two homogenous groups according to live weight and age under a complete randomised block design. Group 1 was fed a traditional diet commonly used by the producer and group 2 was fed an integral feed restricted to 75% of dry matter requirement of lambs. The evaluated variables were: dry matter intake, initial and final live weight, daily weight gain, feed efficiency and body growth expressed in height, body length, thoracic diameter, cane length and cane width. A partial cost analysis was carried out to evaluate the economic viability. Lambs fed with the integral feed had better feed efficiency, higher dry matter intake, daily weight gain, height, body length and thoracic diameter when compared with the lambs fed the traditional diet. The use of an integral feed under a restricted-feeding program reduced the cost of finishing lambs by 2.46 dollars per head and finishing length by 120 days. Overall, providing an integral feed under a restricted-feeding program is a viable alternative for improving finishing lambs under intensive conditions in the Northern Mexico
Effect of high Al2O3 content on the microstructure and electrical properties of Co- and Ta-doped SnO2 varistors
Varistor behavior shows signifcant diferences when the addition levels of diferent dopants like In2O3, Cr2O3, and Al2O3
are changed, thus stimulating current investigations on the SnO2–Co3O4–Ta2O5 ceramic system. In this contribution, the
infuence of high additions of Al2O3 on the microstructure, structure and the electrical properties of SnO2–Co3O4–Ta2O5
varistors ([98.95-X]%SnO2–1% Co3O4–X% Al2O3–0.05% Ta2O5, where X=0, 0.05, 0.1, 1 or 2 mol%) is investigated. Characterization techniques such as thermal analysis, scanning electron microscopy and X-ray difraction with Rietveld refnement
were used for specimen analysis. The endothermic peaks in the ceramic system containing Al2O3 additions between 0.05
and 1% are ascribed to the formation of the Co2SnO4 and CoAl2O4 spinel type phases. Doping the ceramic system with 1
and 2 mol% Al2O3 leads to the formation of 1.163 and 3.449%, respectively, of the spinel phase Al2CoO4, which acts as a
grain growth inhibitor because grain size decreases in about 16% for both addition levels. The apparent grains homogeneity
and narrowest monomodal grain size distribution for the specimens with 2 mol% Al2O3 confrm the inhibitory role. With
the lowest level of Al2O3 (0.05 mol%) the nonlinearity coefcient reaches a maximum, after which it decreases and fades at
the highest alumina level. A remarkable decrease of about 50% in the leakage current from the reference specimen´s value
to that of the one with 0.05 mol% Al2O3 concurrently with an increase in about 40% in the nonlinearity coefcient favors
the potential use of alumina in the SnO2–Co3O4–Ta2O5 ceramic system.El comportamiento del varistor muestra diferencias significativas cuando los niveles de adición de diferentes dopantes como In2O3, Cr2O3 y Al2O3
se modifican, lo que estimula las investigaciones actuales sobre el sistema cerámico SnO2 – Co3O4 – Ta2O5. En esta contribución, el
Influencia de altas adiciones de Al2O3 en la microestructura, estructura y propiedades eléctricas de SnO2 – Co3O4 – Ta2O5
varistores ([98.95-X]% SnO2–1% Co3O4 – X% Al2O3–0.05% Ta2O5, donde X = 0, 0.05, 0.1, 1 o 2% mol) se investiga. Técnicas de caracterización como análisis térmico, microscopía electrónica de barrido y difracción de rayos X con refinamiento de Rietveld.
fueron utilizados para el análisis de muestras. Los picos endotérmicos en el sistema cerámico que contienen adiciones de Al2O3 entre 0.05
y 1% se atribuyen a la formación de las fases de tipo espinela Co2SnO4 y CoAl2O4. Dopando el sistema cerámico con 1
y 2 mol% de Al2O3 conduce a la formación de 1.163 y 3.449%, respectivamente, de la fase de espinela Al2CoO4, que actúa como un
inhibidor del crecimiento del grano porque el tamaño del grano disminuye en aproximadamente un 16% para ambos niveles de adición. La aparente homogeneidad de los granos.
y la distribución de tamaño de grano monomodal más estrecha para las muestras con 2% en moles de Al2O3 confirman el papel inhibidor. Con
el nivel más bajo de Al2O3 (0.05 mol%) el coeficiente de no linealidad alcanza un máximo, después de lo cual disminuye y se desvanece a
El nivel más alto de alúmina. Una disminución notable de aproximadamente el 50% en la corriente de fuga del valor de la muestra de referencia
al de aquel con 0.05 mol% Al2O3 concurrentemente con un aumento de aproximadamente 40% en los favores coeficientes no lineales
El uso potencial de alúmina en el sistema cerámico SnO2 – Co3O4 – Ta2O5
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