108 research outputs found
Tailed U-Net: Multi-Scale Music Representation Learning
Self-supervised learning has steadily been gaining traction in recent years. In music information retrieval (MIR), one promising recent application of self-supervised learning is the CLMR framework (contrastive learning of musical representations). CLMR has shown good performance, achieving results on par with state-of-the-art end-to-end classification models, but it is strictly an encoding framework. It suffers the characteristic limitation of any encoder that it cannot explicitly combine multi-timescale information, whereas a characteristic feature of human audio perception is that we tend to perceive all frequencies simultaneously. To this end, we propose a generalization of CLMR that learns to extract and explicitly combine representations across different frequency resolutions, which we coin the tailed U-Net (TUNe). TUNe architectures combine multi-timescale information during a decoding phase, similar to U-Net architectures used in computer vision and source separation, but have a tail added to reduce sample-level information to a smaller pre-defined number of representation dimensions. The size of the decoding phase is a hyperparameter, and in the case of a zero-layer decoding phase, TUNe reduces to CLMR. The best TUNe architectures, however, require less training time to match CLMR performance, have superior transfer learning performance, and are competitive with state-of-the-art models even at dramatically reduced dimensionalities
Anatomía vascular de los tendones peroneos en el tobillo
Estudiamos la vasculación de los tendones peroneos en el tobillo de 26 miembros inferiores de fetos humanos a término mediante disección. Previamente sometemos a los especímenes a inyección de látex teñido por arteria femoral y posteriormente fijamos en formaldehído.Peer Reviewe
Impact of terrestrial mining and intensive agriculture in pollution of estuarine surface sediments: Spatial distribution of trace metals in the Gulf of Uraba, Colombia
The Gulf of Uraba (northwestern Colombia) is a geostrategic region, rich in biodiversity and natural resources. Its economy is mainly based on agribusinesses and mining activities. In this research is determined the impact of these activities in bottom surface sediments of the estuary. Thus, grain size, total organic carbon, total nitrogen, carbonates, Ag, Al, Ca, Cr, Cu, Fe, Hg, Mg, Mn, Ni, Pb and Zn concentrations from 17 surface sediment samples were obtained and enrichment factors (EF) as well as geo-accumulation indices (Igeo) were calculated to determine the contamination level in the gulf. EF and Igeo values revealed that the estuary is extremely contaminated with Ag and moderately contaminated with Zn. Therefore, the observed enrichment of Ag may be explained as a residue of the extraction of gold and platinum-group metals and the enrichment with Zn associated mainly to pesticides used in banana plantations. (C) 2016 Elsevier Ltd. All rights reserved
First report of Tomato torrado virus on weed hosts in Spain
Alfaro Fernández, AO.; Córdoba-Sellés, C.; Cebrián, M.; Herrera-Vásquez, J.; Sanchez Navarro, JA.; Juárez, M.; Espino, A.... (2088). First report of Tomato torrado virus on weed hosts in Spain. Plant Disease. 92(5):831-831. https://doi.org/10.1094/pdis-92-5-0831b83183192
A mechanism for randomness
We investigate explicit functions that can produce truly random numbers. We
use the analytical properties of the explicit functions to show that certain
class of autonomous dynamical systems can generate random dynamics. This
dynamics presents fundamental differences with the known chaotic systems. We
present realphysical systems that can produce this kind of random time-series.
We report theresults of real experiments with nonlinear circuits containing
direct evidence for this new phenomenon. In particular, we show that a
Josephson junction coupled to a chaotic circuit can generate unpredictable
dynamics. Some applications are discussed.Comment: Accepted in Physics Letters A (2002). 11 figures (.eps
Graviton Excitations and Lorentz-Violating Gravity with Cosmological Constant
Motivated by the interest raised by the problem of Lorenz-symmetry violating
gauge theories in connetion with gravity models, this contribution sets out to
provide a general method to systematically study the excitation spectrum of
gravity actions which include a Lorentz-symmetry breaking Chern-Simons-type
action term for the spin connection. A complete set of spin-type operators is
found which accounts for the (Lorentz) violation parameter to all orders and
graviton propagators are worked out in a number of different situations
Caracterización morfoagronómica de cacao criollo (Theobroma cacao L.) y su incidencia en la selección de germoplasma promisorio en áreas de presencia natural en El Salvador
En El Salvador el cultivo de cacao, se proyecta como un rubro nuevo de producción agrícola tanto en el ámbito nacional como internacional, constituyendo una oportunidad para el desarrollo económico de productores interesados en este cultivo; por tal motivo se realizó un proceso de prospección de esta especie entre el período de octubre 2013 a junio 2014, iniciando colectas de frutos y material vegetativo de cacao en áreas de presencia natural de la especie. El objetivo fue identificar in situ árboles de cacao para la caracterización morfoagronómica, utilizando descriptores adaptados al catálogo de cultivares de cacao del Perú, CATIE y FEDECACAO, se identificaron zonas donde había presencia de la especie, en los municipios de Caluco, en Sonsonate; el Salitre, Ciudad Delgado y Planes de Renderos, San Salvador; Tenancingo, Cuscatlán; San Pedro Nonualco y Santa María Ostuma, La Paz; Ciudad Victoria, Cabañas y Jucuapa, Usulután. Se caracterizaron 21 árboles; cada uno con sus respectivos atributos cualitativos y cuantitativos como: altura del árbol, forma y tamaño de hojas, frutos, semillas y flores. Cada árbol muestreado, fue georeferenciado, con el fin de ubicarlo y generar el mapa de distribución de los mismos a nivel nacional. Asimismo, en el laboratorio de Química Agrícola de la Facultad de Ciencias Agronómicas, se realizó análisis bromatológicos a muestras de frutos, determinando: grasa, proteína, ceniza, hierro, zinc, humedad total, humedad parcial y materia seca. Como resultados de esta investigación, se inició una colección de cacao con atributos sobresalientes, los mayores porcentajes de grasa lo obtuvieron los árboles codificados como: UES-PDP-19, con 56.4%; UES-SPN-7 con 50.67% y UES-SPN-8 con 50.29%; y los mayores porcentajes de proteína se identificaron para las accesiones, UES-SLT-16, con 27.38%; UES-TNG-18, con 23.36%; y UES-SAL-3 con 21.31%; parámetros que son importantes al momento de hacer programas de producción, mejoramiento genético y en la preservación de este germoplasma
Search for varying constants of nature from astronomical observation of molecules
The status of searches for possible variation in the constants of nature from
astronomical observation of molecules is reviewed, focusing on the
dimensionless constant representing the proton-electron mass ratio
. The optical detection of H and CO molecules with large
ground-based telescopes (as the ESO-VLT and the Keck telescopes), as well as
the detection of H with the Cosmic Origins Spectrograph aboard the Hubble
Space Telescope is discussed in the context of varying constants, and in
connection to different theoretical scenarios. Radio astronomy provides an
alternative search strategy bearing the advantage that molecules as NH
(ammonia) and CHOH (methanol) can be used, which are much more sensitive to
a varying than diatomic molecules. Current constraints are
for redshift , corresponding to
look-back times of 10-12.5 Gyrs, and for
, corresponding to half the age of the Universe (both at 3
statistical significance). Existing bottlenecks and prospects for future
improvement with novel instrumentation are discussed.Comment: Contribution to Workshop "High Performance Clocks in Space" at the
International Space Science Institute, Bern 201
Radiological Study of Water for Human Use and Consumption in Rural Areas of the Central Zone of the State of Veracruz, Mexico
A study and spatiotemporal radiological characterization of water for human use and consumption in the main rural populations of the center of the State of Veracruz was carried out, covering 22 municipalities. The objective was to estimate the annual effective dose as a function of the concentration of gross alpha and beta activity. For this purpose, a low background proportional flux detection system calibrated with NIST-traceable radioactive standards was used. Sampling included only wells, springs, and lagoons in rural areas that supply water to these populations. The decision was based on the fact that these do not have a physicochemical treatment and was carried out during the dry and rainy seasons, which became factors of impact on the radiological material. The analysis included the results of 195 samples from 22 municipalities which showed ranges in the gross alpha of 0.052-0.95 BqL-1 with a mean of 0.376 ±0.101BqL-1 and a gross beta of 0.034-1.48 BqL-1 with a mean of 0.389 ±0.108 BqL-1. The comparison of the values obtained with respect to those of other countries and their complement with analysis of variance showed that there was a significant difference, particularly, for the results of gross alpha in the municipality of Alto Lucero de Gutierrez Barrios and gross beta in Nautla and Tecolutla in dry and rainy seasons (at a probability of p≤0.05 with the Tukey-Kramer HSD statistical test). A correlation between gross alpha and gross beta was also performed with an r of -0.18 and -0.44 in dry and rainy seasons. This means that among the radionuclides, the major sources of beta radiation are uranium and thorium decay series radionuclides. For the determination of gross alpha, the municipalities in the mountainous zones showed lower values of this activity than the municipalities in the coastal zone. Gross alpha activity values of 0.95 ± 0.11 BqL-1 were detected in the municipality of Alto Lucero de Gutiérrez Barrios in the locality of Arroyo Agrio, which exceeded the limit of the Official Mexican Standard
The Milky Way Bulge: Observed properties and a comparison to external galaxies
The Milky Way bulge offers a unique opportunity to investigate in detail the
role that different processes such as dynamical instabilities, hierarchical
merging, and dissipational collapse may have played in the history of the
Galaxy formation and evolution based on its resolved stellar population
properties. Large observation programmes and surveys of the bulge are providing
for the first time a look into the global view of the Milky Way bulge that can
be compared with the bulges of other galaxies, and be used as a template for
detailed comparison with models. The Milky Way has been shown to have a
box/peanut (B/P) bulge and recent evidence seems to suggest the presence of an
additional spheroidal component. In this review we summarise the global
chemical abundances, kinematics and structural properties that allow us to
disentangle these multiple components and provide constraints to understand
their origin. The investigation of both detailed and global properties of the
bulge now provide us with the opportunity to characterise the bulge as observed
in models, and to place the mixed component bulge scenario in the general
context of external galaxies. When writing this review, we considered the
perspectives of researchers working with the Milky Way and researchers working
with external galaxies. It is an attempt to approach both communities for a
fruitful exchange of ideas.Comment: Review article to appear in "Galactic Bulges", Editors: Laurikainen
E., Peletier R., Gadotti D., Springer Publishing. 36 pages, 10 figure
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