572 research outputs found
Hasse--Schmidt derivations versus classical derivations
In this paper we survey the notion and basic results on multivariate
Hasse--Schmidt derivations over arbitrary commutative algebras and we associate
to such an object a family of classical derivations. We study the behavior of
these derivations under the action of substitution maps and we prove that, in
characteristic , the original multivariate Hasse--Schmidt derivation can be
recovered from the associated family of classical derivations. Our
constructions generalize a previous one by M. Mirzavaziri in the case of a base
field of characteristic .Comment: Dedicated to L\^e D\~ung Tr\'ang; final version; 2 references added;
minor corrections. arXiv admin note: text overlap with arXiv:1807.10193,
arXiv:1903.0898
Hasse--Schmidt modules versus integrable connections
We prove that, in characteristic 0, any Hasse-Schmidt module structure can be
recovered from its underlying integrable connection, and consequently
Hasse--Schmidt modules and modules endowed with an integrable connection
coincide.Comment: 20 pages; comments are welcome. arXiv admin note: text overlap with
arXiv:1810.08075, arXiv:1807.1019
Keeping watch over Colombia’s slumbering volcanoes
The Volcanological and Seismological Observatories of Manizales, Pasto and Popayan (Colombian Geological Survey) monitor and study the active volcanoes of Colombia using seismological, geodetic, geochemical and other techniques. Since 2009, permanent GNSS stations have been installed to complement classical geodetic measurements (e.g., tilt, EDM). At the moment, there are a total of 20 GNSS stations installed at Nevado del Ruiz, Cerro Machín, Puracé and Galeras volcanoes.
Nevado del Ruiz has remained the most dynamic of the active Colombian volcanoes since its tragic eruption of 13 November 1985. The most significant deformation occurred between 2007 and 2012, when inflation, associated with magma migration and several small to moderate explosive eruptions in 2012 (VEI less or equal to 3), was observed.
Galeras has experienced more than 25 moderate Vulcanian eruptions (VEI less or equal to 3) since 1989. In particular, the deformation network detected significant signals associated with magma migration and the extrusion of lava domes in 1991, 2005, 2008 and 2012.
Puracé volcano has been the site of more than 10 minor eruptive episodes (VEI=2) in the past century, most recently in 1977. Monitoring of this volcano started in 1994. Unrest at Puracé since that time has been characterized by significant increases in seismic activity but with little or no deformation.
We employ GAMIT/GLOBK to process GPS data from the monitoring network with support from the Volcano Disaster Assistance Program (U.S. Geological Survey). Additionally, differential processing is carried out using the commercial package Trimble 4D Control. Preliminary results for 2012 show no significant deformation at Puracé and Galeras volcanoes. On the other hand, the time series from Nevado del Ruiz shows a minor inflation (2-4 cm/yr) associated with the eruptive activity of 2012
USE OF SYNTHETIC TANINES DURING THE SKIN CURTITION PROCESS OF Cavia porcellus (CUY) IN FINE PELETERY
The Cavia porcellus skin (Cuy), after receiving a tanning process, using synthetic tannins, becomes a high quality leather, very suitable in the articles manufacture of high quality. Its main objective was the evaluation of different levels of synthetic tannin (6, 7, 8%) during the tanning process of guinea pig skins with hair; using 48 skins, with an average mass of 200 g each. The experimental units modeled with a Completely Random Design (DCA. Once the experimental phase was completed, it observed that the most skin tanning suitable level the guinea pig (retaining hair) is 6 % of synthetic tanning agent; it´s supported by the excellent results the tests performed. The physical resistance evaluation determined that the best tensile strength (1945.75 N/cm2) it´s reached whit 6 % of synthetic tannin and the best percentage of elongation (89.69 %) achieved with the use of 7 % of tannin (which fully meet the requirements quality the Spanish Leather Association). The most efficient sensorial characteristics obtained with 6 % of tannin: fullness 4.88; softness 4.63 and roundness 4.75 points, respectively; producing a very soft, flexible skin and above all with the fullness suitable for the fine articles manufacture.
Keywords: tanning, skins, guinea pig, synthetic tannins.
Resumen
La piel del Cavia porcellus (Cuy), después de curtida, empleando taninos sintéticos, se convierte en un cuero de alta calidad, muy adecuado en la peletería fina. Esta investigación tuvo por objetivo fundamental la evaluación de diferentes niveles de tanino sintético (6, 7, 8 %) durante el proceso de curtición de pieles de cuyes con pelo; utilizando para ello un total de 48 pieles, con una masa promedio de 200 g cada una. Las unidades experimentales fueron modeladas con un Diseño Completamente al Azar (DCA). Una vez culminada la fase experimental, se pudo constatar que el nivel más adecuado para la curtición de la piel de cuy (conservando el pelo) es del 6 % de curtiente sintético; lo cual quedó avalado por los excelentes resultados de las pruebas practicadas. La evaluación de las resistencias físicas determinó que la mejor resistencia a la tensión (1945,75 N/cm2) se alcanzó al curtir con 6 % de tanino sintético, y el mejor porcentaje de elongación (89,69 %), se logró con la utilización de 7 % de tanino (que satisfacen completamente con las exigencias de calidad de la Asociación Española del Cuero). Las características sensoriales más eficientes fueron logradas al curtir las pieles con 6 % de tanino: llenura 4,88; blandura 4,63 y redondez 4,75 puntos, respectivamente; produciéndose una piel muy suave, flexible y sobre todo con la llenura adecuada para la confección de artículos de peletería fina.
Palabras Clave: Clave: curtición, pieles, cuy, taninos sintéticos
Algebraic computation of some intersection D-modules
Let be a complex analytic manifold, a locally
quasi-homogeneous free divisor, an integrable logarithmic connection with
respect to and the local system of the horizontal sections of on
. In this paper we give an algebraic description in terms of of the
regular holonomic D-module whose de Rham complex is the intersection complex
associated with . As an application, we perform some effective computations
in the case of quasi-homogeneous plane curves.Comment: 18 page
Design and analysis of flow control algorithms for data networks
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1997.Includes bibliographical references (leaves 110-112).by Paolo L. Naváez Guarnieri.M.S
Human myeloid dendritic cells treated with supernatants of rotavirus infected Caco-2 cells induce a poor Th1 response
Q3Q2154-161We have previously shown that human myeloid dendritic cells treated with purified rotavirus induce an allogenic Th1 response. To determine if rotavirus in the context of an intestinal microenvironment modulates the function of dendritic cells, we treated these cells with supernatants from non-infected or infected Caco-2 cells and studied their capacity to promote Th1 or Th2 responses. Dendritic cells treated with supernatants from rotavirus-infected Caco-2 cells promoted a significantly lower Th1 response, in comparison with those treated with purified rotavirus. We wanted to establish if TGF-beta 1, induced, or TSLP, not induced, during rotavirus infection, could mediate this effect. Neutralization of TGF-beta but not TSLP in the supernatant prior to treatment of dendritic cells increased their capacity to promote a Th1 response. The results suggest that the TGF-beta 1 induced by rotavirus could be an immune evasion mechanism, and may partially explain the poor rotavirus-specific T cell response we have previously evidenced. (C) 2011 Elsevier Inc. All rights reserved
Galaxy properties from J-PAS narrow-band photometry
We study the consistency of the physical properties of galaxies retrieved
from SED-fitting as a function of spectral resolution and signal-to-noise ratio
(SNR). Using a selection of physically motivated star formation histories, we
set up a control sample of mock galaxy spectra representing observations of the
local universe in high-resolution spectroscopy, and in 56 narrow-band and 5
broad-band photometry. We fit the SEDs at these spectral resolutions and
compute their corresponding the stellar mass, the mass- and luminosity-weighted
age and metallicity, and the dust extinction. We study the biases,
correlations, and degeneracies affecting the retrieved parameters and explore
the r\^ole of the spectral resolution and the SNR in regulating these
degeneracies. We find that narrow-band photometry and spectroscopy yield
similar trends in the physical properties derived, the former being
considerably more precise. Using a galaxy sample from the SDSS, we compare more
realistically the results obtained from high-resolution and narrow-band SEDs
(synthesized from the same SDSS spectra) following the same spectral fitting
procedures. We use results from the literature as a benchmark to our
spectroscopic estimates and show that the prior PDFs, commonly adopted in
parametric methods, may introduce biases not accounted for in a Bayesian
framework. We conclude that narrow-band photometry yields the same trend in the
age-metallicity relation in the literature, provided it is affected by the same
biases as spectroscopy; albeit the precision achieved with the latter is
generally twice as large as with the narrow-band, at SNR values typical of the
different kinds of data.Comment: 26 pages, 15 figures. Accepted for publication in MNRA
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