255 research outputs found
Maximal Commutative Subalgebras Invariant for CP-Maps: (Counter-)Examples
We solve, mainly by counterexamples, many natural questions regarding maximal
commutative subalgebras invariant under CP-maps or semigroups of CP-maps on a
von Neumann algebra. In particular, we discuss the structure of the generators
of norm continuous semigroups on B(G) leaving a maximal commutative subalgebra
invariant and show that there exists Markov CP-semigroups on M_d without
invariant maximal commutative subalgebras for any d>2.Comment: After the elemenitation in Version 2 of a false class of examples in
Version 1, we now provide also correct examples for unital CP-maps and Markov
semigroups on M_d for d>2 without invariant masa
La (des)iranización de la política exterior de Estados Unidos: el futuro del acuerdo nuclear con Irán bajo la presidencia de Trump
Sumario:
I. Introducción.
II. Principales elementos del acuerdo nuclear.
III. El levantamiento de las sanciones.
IV. El futuro del acuerdo nuclear: ¿descertificación o «desiranización» de la política exterior de EEUU
PASTOR PALOMAR, Antonio: Las formas de manifestación del consentimiento para obligarse por tratados internacionales: análisis de la práctica española, Madrid, Biblioteca Diplomática Española (Sección Varios, 8), Ministerio de Asuntos Exteriores, 2001, 527 págs. [RECENSIÓN]
Comparative study of honey bee production with one and three queens by beehive in nueva imperial, IX region, Chile
In the Region of La Araucanía tests have been made where the production of honey of double queen beehives was compared to single queen beehives, with encouraging results. This motivated the accomplishment of this study in the zone of Nueva Imperial, which compared the conventional production of honey of triple queen systems and systems with one queen by beehive. For the accomplishment of this study 12 beehives were used, nine were grouped to form the triple queen systems and the remaining three with one queen were used as control. The research began on November 4th 2004, with weekly visits to control the factors that could affect the honey productions. The crop was made on January 11th 2005, reaching a honey production of 85 kg average for triple queens systems, which was significantly greater to the production obtained by the systems with a single queen which reached 19,17 kg of honey average.En la Región de La Araucanía se han realizado ensayos donde se comparó la producción de miel de colmenas doble reina y colmenas de una sola reina, con resultados alentadores. Esto motivó la realización de este estudio en la zona de Nueva Imperial, el cual comparó la producción de miel de sistemas de triple reina y sistemas convencionales con una reina por colmena. Para la realización de este estudio se utilizaron 12 colmenas, de las cuales nueve se agruparon para formar los sistemas triple reina, y las tres restantes con una reina fueron utilizadas como testigo. La investigación comenzó el 4 de noviembre del 2004, con visitas semanales, para controlar los factores que pudieran incidir en la producción de miel. La cosecha se realizó el 11 de enero de 2005, alcanzándose producciones promedio de 85 kg de miel para los sistemas triple reina, lo cual fue significativamente mayor a la producción lograda por los sistemas con una sola reina que alcanzaron 19,17 kg de miel promedio
Azadirachtin effectivity in embryogenesis inhibition of Aegorhinus superciliosus (Guérin) (Coleoptera: Curculionidae)
Raspberry is cultivated in the southern part of Chile mainly for export. Its fruit is severely affected by the raspberry weevil (RW) Aegorhinus superciliosus (Guérin), a Curculionidae native of Chile. Little is known about the biology RW and control measures. Conventional insecticides have been tried against the adult, however, their use has been hindered in the practice by the coincidence of the presence of the mature insect with flowering and fructification periods. Entomopathogenic fungi are being incorporated lately, but still not massively used. This work aimed to evaluate azadirachtin, using the commercial product Neem as a growth regulator. Six doses of Neem, 0.5, 1, 2, 3, 4, and 5 ml/L of water, were applied under laboratory conditions, maintaining a check with no insecticide. RW adults stayed confined on the foliage of raspberry bushes treated with Neem during five days and in thirty days during egglaying. Number of eggs, number of emerged larva, percentage of born larva, effectiveness; effective half dose (DE50) and ninety effective dose (DE90) were determined. Neem treatments had significantly lower egg-laying amount, lower emergence of larvae and greater effectiveness, compared to the untreated check. The lowest egg-laying number was obtained with 2 ml of Neem, however, 5 ml of Neem resulted in the smallest number and percent of emerged larvae. DE50 and DE90 were found to be 0.0290 and 8.923 ml of Neem for liter of water, respectively. It was concluded that Neem can significantly alter egg-laying and embryogenesis of the RW.La frambuesa es una fruta de exportación, cuyo cultivo en el sur de Chile es afectado seriamente por el curculiónido Aegorhinus
superciliosus (Guérin) o cabrito del frambueso (CF), insecto nativo de Chile.
La biología del CF es poco conocida y también su control. Se ha intentado reducir al adulto con insecticidas convencionales; sin
embargo, en la práctica se dificulta su uso por coincidir la presencia del insecto adulto con periodos de floración y cosecha de fruta.
Recientemente se están incorporando hongos entomopatógenos, pero aún no se aplican masivamente.
En este trabajo se experimentó con azadirachtina, utilizando el producto comercial Neem como regulador de crecimiento. Bajo
condiciones de laboratorio se aplicaron seis dosis de Neem: 1 ml; 2 ml; 3 ml; 4 ml; 5 ml; 6 ml de Neem por litro de agua. Además,
de un testigo sin insecticida.
Los adultos del CF se mantuvieron confinados con follaje de frambueso tratados con Neem durante cinco días y en postura por
treinta días. Durante este periodo se determinó: cantidad de huevos, cantidad de larvas emergidas, porcentaje de larvas nacidas,
grado de eficacia, dosis media efectiva (DE50) y dosis noventa efectiva (DE90).
Los tratamientos con Neem fueron significativamente diferentes al testigo, presentando menor postura, menor emergencia de larvas
y mayor grado de efectividad. Con 2 ml de Neem se obtuvo la menor postura; sin embargo, la dosis de 5 ml de Neem presentó la
menor cantidad de larvas emergidas y el menor porcentaje de emergencia de larvas. La DE50 se determinó en 0,0290 ml de Neem
y la DE90 en 8,923 ml de Neem por litro de agua.
Con los antecedentes expuestos se concluyó que el Neem tiene un efecto que altera la postura y la embriogénesis del CF
Massive Clumps in the NGC 6334 Star Forming Region
We report observations of dust continuum emission at 1.2 mm toward the star
forming region NGC 6334 made with the SEST SIMBA bolometer array. The
observations cover an area of square degrees with approximately
uniform noise. We detected 181 clumps spanning almost three orders of magnitude
in mass (3\Msun \Msun) and with sizes in the range 0.1--1.0 pc.
We find that the clump mass function is well fit with a power law
of the mass with exponent -0.6 (or equivalently ). The
derived exponent is similar to those obtained from molecular line emission
surveys and is significantly different from that of the stellar initial mass
function. We investigated changes in the mass spectrum by changing the
assumptions on the temperature distribution of the clumps and on the
contribution of free-free emission to the 1.2 mm emission, and found little
changes on the exponent. The Cumulative Mass Distribution Function is also
analyzed giving consistent results in a mass range excluding the high-mass end
where a power-law fit is no longer valid. The masses and sizes of the clumps
observed in NGC 6334 indicate that they are not direct progenitors of stars and
that the process of fragmentation determines the distribution of masses later
on or occurs at smaller spatial scales. The spatial distribution of the clumps
in NGC 6334 reveals clustering which is strikingly similar to that exhibited by
young stars in other star forming regions. A power law fit to the surface
density of companions gives .Comment: 16 pages, 11 figures, 4 tables. To appear in the Astrophysical
Journa
In situ assessment and minimization of nonlinear propagation effects for femtosecond-laser waveguide writing in dielectrics
The effect of nonlinear propagation on the shape of the focal volume has been assessed by in situ plasma emission imaging during the subsurface processing of a commercial phosphate glass. The sample was processed with an elliptically shaped femtosecond-laser beam at 1 kHz repetition rate and scanned transversely with respect to the writing beam axis. As a consequence, optimal conditions for minimizing undesirable nonlinear propagation effects during the production of optical waveguides by direct laser writing have been determined. Under these conditions, it is possible to induce structural transformations and still preserve the focal volume shape associated with the linear propagation regime. While at low pulse energy a single scan laser-written structure does not support a guided mode, the use of multiple scans with minimized nonlinear propagation effects enables the production of optical waveguides. The latter show a significantly improved performance in terms of the refractive index change and propagation losses when compared to single scan waveguides. © 2010 Optical Society of America.This work was partially supported by the University of Zaragoza under Project 223/88 and by the Spanish Ministry of Science and Innovation under TEC2008-01183 project. A. Ruiz de la Cruz and W. Gawelda acknowledge their I3P-CSIC postdoctoral contracts (co-funded by the European Social Fund). D. Puerto and A. Ferrer acknowledge their grants under Projects TEC 2005-00074 and TEC 2006-04538.Peer Reviewe
Magnetostratigraphy of the Cretaceous/Tertiary boundary and early Paleocene sedimentary sequence from the Chicxulub Impact Crater
Periodic Mesoporous Organosilica Nanorice
A periodic mesoporous organosilica (PMO) with nanorice morphology was successfully synthesized by a template assisted sol–gel method using a chain-type precursor. The PMO is composed of D and T sites in the ratio 1:2. The obtained mesoporous nanorice has a surface area of 753 m2 g−1, one-dimensional channels, and a narrow pore size distribution centered at 4.3 nm. The nanorice particles have a length of ca. 600 nm and width of ca. 200 nm
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