1,602 research outputs found
ALMA 690 GHz observations of IRAS 16293-2422B: Infall in a highly optically-thick disk
We present sensitive, high angular resolution ( 0.2 arcsec)
submillimeter continuum and line observations of IRAS 16293-2422B made with the
Atacama Large Millimeter/Submillimeter Array (ALMA). The 0.45 mm continuum
observations reveal a single and very compact source associated with IRAS
16293-2422B. This submillimeter source has a deconvolved angular size of about
400 {\it milli-arcseconds} (50 AU), and does not show any inner structure
inside of this diameter. The HCN, HCN, and CHOH line
emission regions are about twice as large as the continuum emission and reveal
a pronounced inner depression or "hole" with a size comparable to that
estimated for the submillimeter continuum. We suggest that the presence of this
inner depression and the fact that we do not see inner structure (or a flat
structure) in the continuum is produced by very optically thick dust located in
the innermost parts of IRAS 16293-2422B. All three lines also show pronounced
inverse P-Cygni profiles with infall and dispersion velocities larger than
those recently reported from observations at lower frequencies, suggesting that
we are detecting faster, and more turbulent gas located closer to the central
object. Finally, we report a small east-west velocity gradient in IRAS
16293-2422B that suggests that its disk plane is likely located very close to
the plane of the sky.Comment: Accepted to ApJ
PERFORMANCE OF ARTHROBOTRYS SPP., ALONE AND IN COMBINATION WITH PAECILOMYCES LILACINUS, AS BIOCONTROLLERS OF MELOIDOGYNE INCOGNITA IN TOMATO
PERFORMANCE OF ARTHROBOTRYS SPP., ALONE AND IN COMBINATION WITH PAECILOMYCES LILACINUS, AS BIOCONTROLLERS OF MELOIDOGYNE INCOGNITA IN TOMAT
Al/Fe-, Al/Cu- and Al/(Fe-Cu)-pillared clays: Structural features at low Atomic Active Metal Ratios (AMR)
A set of Al/Fe-, Al/Cu- and Al/(Fe-Cu)-pillared clays were prepared from a Colombian bentonite in sodium or natural (Ca/Mg) form as starting materials. The effect of the loading of the second metal(s) (Fe and/or Cu) related to Al (AMR) in the intercalating solutions at low range of values ≤ 10%, on the main physicochemical properties was investigated. The insertion of the active metals rose almost linearly with AMR for both binary, Al/Fe- and Al/Cu- mixed metal systems. For the three-metal Al/(Fe-Cu)- mixed system, the stabilization of copper behaved randomly as a function of AMR, while the stabilization of Fe was almost not affected by the presence of Cu. On the basis of the ionic radii of the metals involved, a possible competition of the two active metals for the octahedral sites available in the Al13 polycationic structure is proposed for the three-metal system (ionic radii values: Al3+ = 0.68 Å; Fe3+ = 0.67 Å; Cu2+ = 0.73 Å), but also as a good explanation for the efficiency of stabilization for iron around 15 times higher than copper in the binary metal systems. A clear dependence of the compensation of the cationic exchange capacity by polycations with the AMR value was found only for the system Al/Fe-, which was explained in terms of the opposite changes in the final pH obtained in the intercalating solutions, induced by the active metals in the Keggin-like polycations. The change in the basal spacings obtained in the XRD patterns from oriented glasses as a function of AMR was interpreted in terms of the opposite effect expected on the molecular size of the polycations as higher amounts of Fe or Cu would isomorphically substitute Al into the Al13 framework, allowing to propose that both, iron and copper are able to carry out such a substitution, although in different extent. The hydrogen consumption in the H2-TPR analysis of the materials was mainly distributed between two broad peaks: one from about 250ºC to 580ºC, and a second one from about 750ºC to 950ºC. Despite the several metal oxide species that are possible to form, the first signal in samples modified with the Al/Fe- system may correspond with the sequential overlapped reduction of Fe2O3 in up to three steps: (1) Fe2O3 → Fe3O4; (2) Fe3O4 → FeO; and (3) FeO → Fe, and to two sequential reduction effects in the range of 210-260 ºC for Cu2+→ Cu+ and Cu+→ Cu0 at higher temperatures of ca. 400 ºC to 700 ºC. In the Al/Fe- system two shoulders were observed at around 600ºC and 850ºC, whose intensity grow as the active metal loading increases, seem to be related to two kinds of metal sites repeatedly claimed in the literature as responsible for the high catalytic activity displayed by these materials in Fenton-like reactions; Fe “decorating” Al pillars and true mixed Al/Fe pillars, respectively. The textural analysis of the natural modified samples suggest that at AMR below 5.0 %, a discrete maximum exist for the systems Al/Fe- and Al/Cu- over which the sorption capacity starts to be significantly affected. Simultaneous thermal analysis (DSC/TGA) demonstrated that the addition of a second metal in the intercalating system enhanced more the fraction of physisorbed water and decreased the maximum temperature for such a thermal event than intercalation with simple Al- polycations. SEM micrographs showed significant changes in morphology of the particles as AMR increased from 2.0 to 5.0%; as the amount of iron and/or copper added to the system increased, a greater amount of tiny particles deposited on the clay surface was seen, may be corresponding with external oxide aggregates. Likewise, the ratio Fe/Al obtained from the semi-quantitative surface chemical EDX analysis of the samples modified with the system Al/Fe- indicated that the AMR increasing also leads to higher fraction of the iron inserted represented in intercalated, possibly less aggregated mixed species in the materials. Acknowledgements: Financial support from MEC and FEDER funds (Ref. MAT2007-66439-C02)
The Kuramoto model: A simple paradigm for synchronization phenomena
Synchronization phenomena in large populations of interacting elements are the subject of intense research efforts in physical, biological, chemical, and social systems. A successful approach to the problem of synchronization consists of modeling each member of the population as a phase oscillator. In this review, synchronization is analyzed in one of the most representative models of coupled phase oscillators, the Kuramoto model. A rigorous mathematical treatment, specific numerical methods, and many variations and extensions of the original model that have appeared in the last few years are presented. Relevant applications of the model in different contexts are also included
Respuesta ósea al implante del compuesto beta-fosfato tricálcico-colágeno (ß-ftc-c). Estudio «in vivo» en conejos
Se ha estudiado la correlación entre los hallazgos histológicos y las imágenes radiológicas
de un compuesto de beta-fosfato tricálcico y colágeno (ß-FTC-C) después de su implantación
en defectos óseos creados experimentalmente en 21 conejos de 4 Kg de peso
medio. Bajo anestesia general los defectos óseos creados en ambos fémures se rellenaron con
un cilindro de 4,5 x 6 mm del compuesto. Los animales fueron sacrificados a la semana y 1, 2,
4 y 12 meses del postoperatorio. Las muestras obtenidas fueron sometidas a estudio radiográfico
e histológico. Microscópicamente se comprobó que el compuesto a lo largo del período de
implantación sufrió un proceso de reabsorción progresiva mediado por células de estirpe macrofágica
y que se correspondió con una disminución de la densidad radiológica y cambios en
su morfología. A los doce meses del postoperatorio se observaron escasos restos del material,
hecho que se corresponde con la desaparición del implante en la placa radiográfica.The correlation between histologic and radiological findings was studied after
implantation of a composite (ß-FTC-C) into osseus defects which were experimentally induced
in 21 rabbits. Under general anaesthetic osseus defects were made in both femurs and filled
in with a 4,5 x 6 mm composite cylinder. The animals were killed at the first week and,
one, two, four and twelve months after surgery. X-ray study and microscopic examination
were made in all the specimens. Troughout the implantation period, it was microscopically
proven that the composite showed a progressive reabsortion process, mediated by cells of
macrophagus lineage. A decrease in radiologic density and changes in its morphology were
also observed. At the end of the study (twelve months), limited traces of the material could
be seen, in correlation with the images of the X-ray films which revealed the total absence of
the composite implant
Sipuncula inhabiting the coral Oculina patagonica in the western Mediterranean Sea
Background: We analyzed the sipunculan fauna inhabiting the scleractinian coral Oculina patagonica in the Marine Reserve of Tabarca Island (western Mediterranean). Results: Five sipunculan species were collected from 2011 to 2014: Phascolosoma stephensoni, P. granulatum, P. cf. agassizii, Aspidosiphon misakiensis, and Golfingia vulgaris. All five species were reported for the first time inhabiting O. patagonica; with P. cf. agassizii being a new record for the Iberian Peninsula. The average abundance of sipunculans inhabiting the coral was 468.75 ± 158.04 ind m−2, representing the second most abundant taxonomic group, in biomass, after Mollusca. Conclusions: Sipunculan diversity was low comparing with tropical reefs, but species abundances were higher than in soft-bottom nearby areas and community structure appears to be more homogeneous. There may be a considerable contribution to the erosion of the coral skeleton by sipunculans
Glimpse: A gaze-based measure of temporal salience
Temporal salience considers how visual attention varies over time. Although visual salience
has been widely studied from a spatial perspective, its temporal dimension has been mostly ignored,
despite arguably being of utmost importance to understand the temporal evolution of attention
on dynamic contents. To address this gap, we proposed GLIMPSE, a novel measure to compute
temporal salience based on the observer-spatio-temporal consistency of raw gaze data. The measure
is conceptually simple, training free, and provides a semantically meaningful quantification of
visual attention over time. As an extension, we explored scoring algorithms to estimate temporal
salience from spatial salience maps predicted with existing computational models. However, these
approaches generally fall short when compared with our proposed gaze-based measure. GLIMPSE
could serve as the basis for several downstream tasks such as segmentation or summarization of
videos. GLIMPSE’s software and data are publicly available
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