1,242 research outputs found
Directional emission of stadium-shaped micro-lasers
The far-field emission of two dimensional (2D) stadium-shaped dielectric
cavities is investigated. Micro-lasers with such shape present a highly
directional emission. We provide experimental evidence of the dependance of the
emission directionality on the shape of the stadium, in good agreement with ray
numerical simulations. We develop a simple geometrical optics model which
permits to explain analytically main observed features. Wave numerical
calculations confirm the results.Comment: 4 pages, 8 figure
Implications of Growing Biofuels Demands on Northeast Livestock Feed Costs
The relationship between complete-feed prices and commodity feedstock prices are estimated to analyze the effect of higher commodity prices on feed costs, with particular attention towards the price effects and substitutability of corn distillers dried grains with solubles (DDGS). Assuming the historical positive correlation between corn and DDGS prices, each 0.45 and $0.67 across livestock sectors. A negative price correlation would offset some of the cost increases, but under most scenarios feed costs are expected to be at or above those experienced in 2007.Agricultural Finance,
Étude en microscopie électronique à balayage de l'installation de deux souches de Xanthomonas campestris pv manihotis sur feuilles de vitroplants de manioc
L'installation de 2 souches de Xanthomonas campestris pv manihotis, agressive (XCM17) et non agressive (XCM4), est suivie conjointement par numération et par microscopie électronique à balayage, sur des vitroplants de manioc. Les observations réalisées en microscopie électronique à balayage confirment la dynamique de population des 2 souches et permettent aussi de localiser les bactéries à la surface des tissus. Immédiatement après inoculation, l'aspect et la répartition des bactéries à la surface du limbe sont identiques quelle que soit la souche. Six jours après inoculation, la souche non agressive (XCM4) qui ne se multiplie pas ou peu à la surface du limbe n'entraîne pas d'altération des tissus foliaires. L'observation décèle la présence d'un voile recouvrant les cellules bactériennes. Dans les mêmes conditions, la souche agressive (XCM17) se multiplie rapidement ; on note la présence d'amas bactériens à proximité des stomates et les tissus présentent des altérations importantes. La méthode d'inoculation mise au point sur vitroplants de manioc permet de reproduire les symptômes caractéristiques de la maladie et de retrouver le comportement attendu des variétés utilisées. La culture in vitro fournit un matériel commode pour l'étude par différentes techniques des premières étapes de l'infection
A First Comparison of Millimeter Continuum and Mg II Ultraviolet Line Emission from the Solar Chromosphere
We present joint observations of the Sun by the Atacama Large
Millimeter/submillimeter Array (ALMA) and the Interface Region Imaging
Spectrograph (IRIS). The observations were made of a solar active region on
2015 December 18 as part of the ALMA science verification effort. A map of the
Sun's continuum emission of size was obtained by ALMA at a
wavelength of 1.25 mm (239 GHz) using mosaicing techniques. A contemporaneous
map of size was obtained in the Mg II h doublet line at
2803.5\AA\ by IRIS. Both mm/submm continuum emission and ultraviolet
(UV) line emission are believed to originate from the solar chromosphere and
both have the potential to serve as powerful and complementary diagnostics of
physical conditions in this poorly understood layer of the solar atmosphere.
While a clear correlation between mm- brightness temperature and
the Mg II h line radiation temperature is observed the slope is ,
perhaps as a result of the fact that these diagnostics are sensitive to
different parts of the chromosphere and/or the Mg II h line source function
includes a scattering component. There is a significant offset between the mean
(1.25 mm) and mean (Mg II), the former being
greater than the latter. Partitioning the maps into "sunspot", "quiet regions",
and "plage regions" we find that the slope of the scatter plots between the
IRIS Mg II h line and the ALMA brightness temperature is 0.4
(sunspot), 0.56 (quiet regions), and 0.66 (plage regions). We suggest that this
change may be caused by the regional dependence of the formation heights of the
IRIS and ALMA diagnostics, and/or the increased degree of coupling between the
UV source function and the local gas temperature in the hotter, denser gas in
plage regions.Comment: 8 pages, 2 figure
Silicon-on ceramic process: Silicon sheet growth and device development for the large-area silicon sheet task of the low-cost solar array project
The technical feasibility of producing solar-cell-quality sheet silicon to meet the Department of Energy (DOE) 1986 overall price goal of $0.70/watt was investigated. With the silicon-on-ceramic (SOC) approach, a low-cost ceramic substrate is coated with large-grain polycrystalline silicon by unidirectional solidification of molten silicon. This effort was divided into several areas of investigation in order to most efficiently meet the goals of the program. These areas include: (1) dip-coating; (2) continuous coating designated SCIM-coating, and acronym for Silicon Coating by an Inverted Meniscus (SCIM); (3) material characterization; (4) cell fabrication and evaluation; and (5) theoretical analysis. Both coating approaches were successful in producing thin layers of large grain, solar-cell-quality silicon. The dip-coating approach was initially investigated and considerable effort was given to this technique. The SCIM technique was adopted because of its scale-up potential and its capability to produce more conventiently large areas of SOC
Circular dielectric cavity and its deformations
The construction of perturbation series for slightly deformed dielectric
circular cavity is discussed in details. The obtained formulae are checked on
the example of cut disks. A good agreement is found with direct numerical
simulations and far-field experiments.Comment: 17 pages, 12 figure
A novel metric for coronal MHD models
[1] In the interest of quantitatively assessing the capabilities of coronal MHD models, we have developed a metric that compares the structures of the white light corona observed with SOHO LASCO C2 to model predictions. The MAS model is compared to C2 observations from two Carrington rotations during solar cycle 23, CR1913 and CR1984, which were near the minimum and maximum of solar activity, respectively, for three radial heights, 2.5 R⊙, 3.0 R⊙, and 4.5 R⊙. In addition to simulated polarization brightness images, we create a synthetic image based on the field topology along the line of sight in the model. This open-closed brightness is also compared to LASCO C2 after renormalization. In general, the model\u27s magnetic structure is a closer match to observed coronal structures than the model\u27s density structure. This is expected from the simplified energy equations used in current global corona MHD models
Low level of virological failure and drug resistance among patients receiving antiretroviral treatment under programme conditions in Maputo, Mozambique
Mexico AIDS Conference 200
Does the Name Matter? Developing Brands for Patented Fruit Varieties
WP 2011-16 August 2011JEL Classification Codes: M37; Q13Brands have largely been absent for fresh produce products; however, apples are one notable exception whereby varieties partially take the place of brands. Studying the role of brands in this market is particularly interesting given the introduction of several patented or socalled managed apple varieties. We develop an experiment to examine consumer response to a suite of apple varieties; treatments employ different branding strategies using different names for a new managed variety included in the experiment. Results suggest that the name does influence consumer valuation of the new variety and existing managed varieties, but has little impact on markets for traditional apple varieties
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