843 research outputs found
Tiller Dynamic of Guineagrass (\u3cem\u3ePanicum maximum\u3c/em\u3e) Under Defoliation
Guineagrass (Panicum maximum) is a perennial warm season bunchgrass native to Africa that has been introduced to many tropical areas. Its management is important because of its important role in animal production. Total production of herbage and the persistence of tufted grasses can be markedly reduced when the grass is defoliated too frequently and too intensively (Clavero, 1997). In order to determine the proper management for optimum production and long term persistence, it is important to study the effect of cutting practices on tiller dynamics of guineagrass
Magnetic field modulation of intense surface plasmon polaritons
We present correlated experimental and theoretical studies on the magnetic field modulation of Surface Plasmon Polaritons (SPPs) in Au/Co/Au trilayers. The trilayers were grown by sputter deposition on glass slides with the Co films placed at different distances from the surface and with different thickness. We show that it is possible to tailor Au/Co/Au trilayers with the critical thickness needed for optimum excitation of SPPs leading to large localized electromagnetic fields. The modification of the SPP wave vector by externally applied magnetic fields was investigated by measuring the magneto-optical activity in transverse configuration. In addition, using magneto-optics as a tool we determined the spatial distribution of the SPP generated electromagnetic fields within Au/Co/Au samples by analyzing the field-dependent optical response, demonstrating that it is possible to excite SPPs that exhibit large electromagnetic fields that are also magneto-optically active and therefore can be modulated by externally applied magnetic fields. (C)2010 Optical Society of Americ
Separation of Long-Crested Nonlinear Bichromatic Waves into Incident and Reflected Components
Methods for the separation of long-crested linear waves into incident and reflected waves
have existed for more than 40 years. The present paper presents a new method for the separation
of nonlinear bichromatic long-crested waves into incident and reflected components, as well as
into free and bound components. The new method is an extension of a recently proposed method
for the separation of nonlinear regular waves. The new methods include both bound and free
higher harmonics, which is important for nonlinear waves. The applied separation method covers
interactions to the third order, but can easily be extended to a higher orders. Synthetic tests, as well as
physical model tests, showed that the method accurately predict the bound amplitudes and incident
and reflected surface elevations of nonlinear bichromatic waves. The new method is important
in order to be able to describe the detailed characteristics of nonlinear bichromatic waves and
their reflection
Lactococcus garvieae endocarditis in a patient undergoing chronic hemodialysis. First case report in Chile and review of the literature
Indexación: Scopus; Scielo.Los casos reportados de infección por Lactococcus garvieae son escasos y sólo uno asociado a hemodiálisis. Comunicamos el caso de endocarditis infecciosa de curso fatal por L. garvieae en un paciente con una enfermedad renal crónica sometido a hemodiálisis y portador de diverticulosis colónica no complicada. Se realiza una revisión de los casos publicados y se discuten los actuales desafíos diagnósticos y terapéuticos de este patógeno, capaz de producir infecciones graves y potencialmente fatales en pacientes susceptibles. Este sería el segundo caso de infección asociada a hemodiálisis y el primero reportado en Chile.Reports of Lactococcus garvieae infections in humans are scarce, and only one of them in a patient under-going hemodialysis. We report the first case of Lactococcus garvieae infection in Chile, presenting as an infective endocarditis, ultimately fatal, in a patient with uncomplicated colonic diverticulosis and end stage renal failure undergoing chronic hemodialysis. We review the published cases and discuss the diagnostic and therapeutic challenges associated with this new, increasingly diagnosed pathogen, capable of producing serious infections in susceptible patients.https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0716-10182017000400397&lng=en&nrm=iso&tlng=e
The subjective metric of remembered colors: A Fisher-information analysis of the geometry of human chromatic memory.
In order to explore the metric structure of the space of remembered colors, a computer game was designed, where players with normal color vision had to store a color in memory, and later retrieve it by selecting the best match out of a continuum of alternatives. All tested subjects exhibited evidence of focal colors in their mnemonic strategy. We found no concluding evidence that the focal colors of different players tended to cluster around universal prototypes. Based on the Fisher metric, for each subject we defined a notion of distance in color space that captured the accuracy with which similar colors where discriminated or confounded when stored and retrieved from memory. The notions of distance obtained for different players were remarkably similar. Finally, for each player, we constructed a new color scale, in which colors are memorized and retrieved with uniform accuracy
Island-assisted interface alloying and magnetic polarization at submonolayer V/Cr(001) interfaces
Island-assisted interface alloying was observed during submonolayer deposition on Cr(001) substrates at 525 K. Scanning tunneling spectroscopy suggests atomic interchange at the center of the islands during the early stages of growth, giving rise to a Cr core in the center of the island and a gradually increasing V concentration toward the island rim. The existence of a VCr alloy with equiatomic composition is concluded by comparing tunneling spectra measured at the island rim with density-functional theory calculations. Coalescence of the initial islands gives rise to inhomogeneous alloying at monolayer coverage. Antiferromagnetic coupling between the islands and the Cr(001) substrate is found for coverages up to 0.50 atomic layers. At higher coverages, no magnetic contrast was observed
Implementación de un sistema de escenarios futuros sobre el mapa de usos de suelo de Andalucía.
La Consejería de Medio Ambiente (CMA) ha puesto en marcha un estudio para la generación de cartografía
prospectiva de usos de suelo en la Andalucía del siglo XXI. El objeto de este proyecto es explorar y analizar la posible
evolución a medio-largo plazo de los usos del suelo y sus implicaciones ambientales, en un contexto de cambio
global según diferentes escenarios. Los estudios prospectivos tales como, la construcción de escenarios, permiten
iluminar la toma de decisiones. La distribución de los usos de suelo influye en el crecimiento y desarrollo de nuestra
sociedad y representa un elemento importante para predecir los impactos ambientales.
Actualmente la CMA dispone de una cartografía con los más elevados niveles de detalle y precisión espacial, que
cumple los estándares cartográficos internacionales, y que cubre los últimos 50 años en la evolución de los usos del
suelo en nuestra región. El poder anticipar, bajo diferentes supuestos de desarrollo socioeconómico, la evolución y la
distribución de los usos del suelo en el futuro, supondría avanzar y complementar esta línea de trabajo. La
integración de estos factores se ha llevado a cabo mediante autómatas celulares utilizados para modelar los
cambios de uso y el desarrollo urbano.The Environmental Ministry of the Andalusian Regional Government has initiated a study to generate prospective
mapping of land uses in Andalusia in the XXI century. The goal of this project is to explore and analyze medium to
long- term land uses changes and their environmental implications according to different scenarios in the context of global change. Predicting land use change under such scenarios will provide valuable information to decision
makers. The distribution of the land uses influences in the growth and development of our society and thus
represents a crucial element to predict future environmental impacts.
The Environmental Ministry of Andalusia currently has maps available that depict land use changes in the region
over the past 50 years and contain the highest level of detail and spatial precision according to international
cartographic standards. The power to predict the growth and distribution of future land uses under different
assumptions of socioeconomic development will advance and complement this work. The integration of these factors
is carried out based on cellular automata applied to model land use changes and urban development
Roughness analysis applied to niobium thin films grown on MgO(001) surfaces for superconducting radio frequency cavity applications
This paper describes surface studies to address roughness issues inherent to thin film coatings deposited onto superconducting radio frequency (SRF) cavities. This is particularly relevant for multilayered thin film coatings that are being considered as a possible scheme to overcome technical issues and to surpass the fundamental limit of similar to 50 MV/m accelerating gradient achievable with bulk niobium. In 2006, a model by Gurevich [Appl. Phys. Lett. 88, 012511 (2006)] was proposed to overcome this limit that involves coating superconducting layers separated by insulating ones onto the inner walls of the cavities. Thus, we have undertaken a systematic effort to understand the dynamic evolution of the Nb surface under specific deposition thin film conditions onto an insulating surface in order to explore the feasibility of the proposed model. We examine and compare the morphology from two distinct Nb/MgO series, each with its own epitaxial registry, at very low growth rates and closely examine the dynamical scaling of the surface features during growth. Further, we apply analysis techniques such as power spectral density to the specific problem of thin film growth and roughness evolution to qualify the set of deposition conditions that lead to successful SRF coatings. DOI: 10.1103/PhysRevSTAB.16.02200
Order and phase nucleation in nonequilibrium nanocomposite Fe-Pt thin films with perpendicular magnetic anisotropy
We report on the time evolution of mass transport upon annealing nonequilibrium Fe-Pt nanocomposite films, leading to nucleation of L1(0) chemically ordered phase. The nonequilibrium nanocomposite films were fabricated by applying Fe(+) ion implantation to epitaxial Pt films grown on (001) MgO substrates, yielding Fe nanoclusters embedded in a Pt matrix at a tailored penetration depth. Time-resolved x-ray diffraction studies were carried out using synchrotron radiation, allowing determination of the activation energy for nucleation of the FePt L1(0) phase within the segregated nanoclusters during annealing. The growth of the segregated L1(0) ordered phase was modeled using ideal grain-size law and found to be dominated by strain-driven surface nucleation. The activation energies were found to correlate with the nanocluster size. Magnetic characterization of selected annealed samples indicates perpendicular magnetic anisotropy with high coercive field coincident with high value of the chemical order parameter of the ordered phase within the magnetic nanoclusters
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