18,127 research outputs found
Superlens made of a metamaterial with extreme effective parameters
We propose a superlens formed by an ultra-dense array of crossed metallic
wires. It is demonstrated that due to the anomalous interaction between crossed
wires, the structured substrate is characterized by an anomalously high index
of refraction and supports strongly confined guided modes with very short
propagation wavelengths. It is theoretically proven that a planar slab of such
structured material makes a superlens that may compensate for the attenuation
introduced by free-space propagation and restore the subwavelength details of
the source. The bandwidth of the proposed device can be quite significant since
the response of the structured substrate is non-resonant. The theoretical
results are fully supported by numerical simulations.Comment: Accepted for publication in Phys. Rev. B (in press
Doenças do trigo causada por Pseudomonas syringae Patovars.
bitstream/CNPT-2010/40599/1/p-co234.pd
Detection of new eruptions in the Magellanic Clouds LBVs R 40 and R 110
We performed a spectroscopic and photometric analysis to study new eruptions
in two luminous blue variables (LBVs) in the Magellanic Clouds. We detected a
strong new eruption in the LBV R40 that reached in 2016, which is
around mag brighter than the minimum registered in 1985. During this new
eruption, the star changed from an A-type to a late F-type spectrum. Based on
photometric and spectroscopic empirical calibrations and synthetic spectral
modeling, we determine that R\,40 reached ~K
during this new eruption. This object is thereby probably one of the coolest
identified LBVs. We could also identify an enrichment of nitrogen and r- and
s-process elements. We detected a weak eruption in the LBV R 110 with a maximum
of mag in 2011, that is, around mag brighter than in the
quiescent phase. On the other hand, this new eruption is about mag
fainter than the first eruption detected in 1990, but the temperature did not
decrease below 8500 K. Spitzer spectra show indications of cool dust in the
circumstellar environment of both stars, but no hot or warm dust was present,
except by the probable presence of PAHs in R\,110. We also discuss a possible
post-red supergiant nature for both stars
A predictive model for daily inoculum levels of Gibberella zeae in Passo Fundo, Brazil.
The deposition of spores of Gibberella zeae, the causal agent of Fusarium head blight of wheat, was monitored during 2008–2011, in Passo Fundo, RS, Brazil. The sampling was carried out in a 31-day period around wheat flowering. The numbers of colonies formed were related to meteorological variables. In this study, a hierarchical autoregressive binary data model was used. The model relates a binary response variable to potential covariates while accounting for dependence over discrete time points. This paper proposes an approach for both model parameter inference and prediction at future time points using the Markov chain Monte Carlo (MCMC). The developed model appeared to have a high degree of accuracy and may have implications in the disease control and risk-management planning
An infrared diagnostic for magnetism in hot stars
Magnetospheric observational proxies are used for indirect detection of
magnetic fields in hot stars in the X-ray, UV, optical, and radio wavelength
ranges. To determine the viability of infrared (IR) hydrogen recombination
lines as a magnetic diagnostic for these stars, we have obtained low-resolution
(R~1200), near-IR spectra of the known magnetic B2V stars HR 5907 and HR 7355,
taken with the Ohio State Infrared Imager/Spectrometer (OSIRIS) attached to the
4.1m Southern Astrophysical Research (SOAR) Telescope. Both stars show definite
variable emission features in IR hydrogen lines of the Brackett series, with
similar properties as those found in optical spectra, including the derived
location of the detected magnetospheric plasma. These features also have the
added advantage of a lowered contribution of stellar flux at these wavelengths,
making circumstellar material more easily detectable. IR diagnostics will be
useful for the future study of magnetic hot stars, to detect and analyze
lower-density environments, and to detect magnetic candidates in areas obscured
from UV and optical observations, increasing the number of known magnetic stars
to determine basic formation properties and investigate the origin of their
magnetic fields.Comment: 4 pages, accepted for publication in A&
Clinical, histological and prognostic features of a novel nail-bed lesion of cats: 41 cases
There is a distinct subset of lesions arising on the digits of cats, located at or close to the nail-bed epithelium, which are typically composed of proliferative fibroblast-like cells, multinucleate giant cells and areas of osseous metaplasia, but currently there is no published literature detailing the clinical or histological features of these lesions. This study identified 41 such cases from two large commercial diagnostic laboratories and assessed various histological and clinical features; 22 cases had additional follow-up data available
Ensaios preliminares e cooperativos de fungicidas - resultados obtidos no Centro Nacional de Pesquisa de Trigo no perÃodo 1988-1991.
bitstream/item/119426/1/FOL-05091.pdfTÃtulo da capa: Controle quÃmico de doenças do trigo: resultados de 1988 a 1991
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