706 resultados para 924
Resumo:
Forty-one samples from the lower section (between approximately 370 and 495.5 mbsf) drilled at ODP Site 738 (southern Kerguelen Plateau) were analyzed for their palynomorph content. The majority proved to be palynologically barren. Twenty-one species and subspecies of dinoflagellate cysts were recorded, however, from the eight samples that proved productive. The irregular distribution of the cysts makes accurate age determinations difficult, particularly for the lower part of the succession. However, species recovered from Cores 119-738C-21R to 119-738C-23R indicate a latest Maastrichtian age.
Resumo:
An integrated instrument package for measuring and understanding the surface radiation budget of sea ice is presented, along with results from its first deployment. The setup simultaneously measures broadband fluxes of upwelling and downwelling terrestrial and solar radiation (four components separately), spectral fluxes of incident and reflected solar radiation, and supporting data such as air temperature and humidity, surface temperature, and location (GPS), in addition to photographing the sky and observed surface during each measurement. The instruments are mounted on a small sled, allowing measurements of the radiation budget to be made at many locations in the study area to see the effect of small-scale surface processes on the large-scale radiation budget. Such observations have many applications, from calibration and validation of remote sensing products to improving our understanding of surface processes that affect atmosphere-snow-ice interactions and drive feedbacks, ultimately leading to the potential to improve climate modelling of ice-covered regions of the ocean. The photographs, spectral data, and other observations allow for improved analysis of the broadband data. An example of this is shown by using the observations made during a partly cloudy day, which show erratic variations due to passing clouds, and creating a careful estimate of what the radiation budget along the observed line would have been under uniform sky conditions, clear or overcast. Other data from the setup's first deployment, in June 2011 on fast ice near Point Barrow, Alaska, are also shown; these illustrate the rapid changes of the radiation budget during a cold period that led to refreezing and new snow well into the melt season.
Resumo:
With a 6-channel integrating nephelometer spectral scattering properties of the atmospheric aerosol have been measured during the third part of the Atlantic Expedition 1969. A meridional cross section of light scattering integrals in the wavelength range 0.475 µm to 0.924 µm was recorded reaching from 10° S to 60° N along 30° W. With a new algorithm the time series of hourly scattering spectra was inverted yielding a first meridional cross section of the median radius of the number size distribution in situ. Three air mass regimes could be distinguished in the course of the experiment, the first one being the extremely clean air of the SE-trade south of the ITC. An abrupt increase in light scattering marked the hemispheric change when the ship entered the NE-trade which was heavily loaded with Sahara dust. North of the trade region the ship sailed through maritime North Atlantic air masses with highly variable light scattering and a slow decrease in median radius with latitude.
Resumo:
La herramienta de descubrimiento que ha dado lugar al llamado catálogo de próxima generación o NextGen es una interfaz ensamblada a la base de datos del catálogo en línea, que proporciona opciones similares a las de los motores de búsqueda de la World Wide Web. Entre las características más importantes se pueden mencionar: búsqueda por palabras claves del usuario, corrección de ortografía, asociación de palabras por prefijos y sufijos, gradación por relevancia, búsqueda booleana guiada, navegación facetada, ofrecimiento de ítems relacionados, servicios personalizados como MiCuenta o MiBiblioteca, opciones de diseño, características de la Web social como etiquetado o folksonomía, inclusión de reseñas, anotaciones o calificaciones por parte de los usuarios, aportes de la producción propia, creación de grupos de interés, etc. El desafío que se presenta es repensar el catálogo de modo que contribuya a descubrir la información del modo más eficiente posible, con inclusión de resúmenes, notas de contenido o vínculo al texto completo de los documentos. Existen experiencias basadas en programas comerciales como el catálogo de las bibliotecas de la North Carolina State University (Sirsi/Dynyx + interfaz Endeca) y otras con recursos open source como la de BRAC University de Bangladesh (Koha + Vufind). Se considera que esta última experiencia puede ser de interés para las bibliotecas de nuestro medio.