1,376 research outputs found
Characterization of viral determinants of herpes simplex virus type 1 pathogenesis by bioimagery
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Oxygen isotope ratios of large cosmic spherules: Carbonaceous and ordinary chondrite parent bodies
A new micrometeorite collection from Antarctica and its preliminary characterization by magnetic methods
Effect of nicotinamide on RNA and DNA synthesis and on poly(ADP-ribose) polymerase activity in normal and phytohemagglutinin stimulated human lymphocytes
Spatio-temporal variability of the North Sea cod recruitment in relation to temperature and zooplankton
The North Sea cod (Gadus morhua, L.) stock has continuously declined over the past four decades linked with overfishing
and climate change. Changes in stock structure due to overfishing have made the stock largely dependent on its
recruitment success, which greatly relies on environmental conditions. Here we focus on the spatio-temporal variability of
cod recruitment in an effort to detect changes during the critical early life stages. Using International Bottom Trawl Survey
(IBTS) data from 1974 to 2011, a major spatio-temporal change in the distribution of cod recruits was identified in the late
1990s, characterized by a pronounced decrease in the central and southeastern North Sea stock. Other minor spatial
changes were also recorded in the mid-1980s and early 1990s. We tested whether the observed changes in recruits
distribution could be related with direct (i.e. temperature) and/or indirect (i.e. changes in the quantity and quality of
zooplankton prey) effects of climate variability. The analyses were based on spatially-resolved time series, i.e. sea surface
temperature (SST) from the Hadley Center and zooplankton records from the Continuous Plankton Recorder Survey. We
showed that spring SST increase was the main driver for the most recent decrease in cod recruitment. The late 1990s were
also characterized by relatively low total zooplankton biomass, particularly of energy-rich zooplankton such as the copepod
Calanus finmarchicus
, which have further contributed to the decline of North Sea cod recruitment. Long-term spatially-
resolved observations were used to produce regional distribution models that could further be used to predict the
abundance of North Sea cod recruits based on temperature and zooplankton food availability.Publicado
57Fe Mössbauer spectroscopy studies of chondritic meteorites from the Atacama Desert, Chile: Implications for weathering processes
Some terrestrial areas have climatic and geomorphologic features that favor the preservation, and therefore, accumulation of meteorites. The Atacama Desert in Chile is among the most important of such areas, known as dense collection areas. This desert is the driest on Earth, one of the most arid, uninhabitable locals with semi-arid, arid and hyper-arid conditions. The meteorites studied here were collected from within the dense collection area of San Juan at the Central Depression and Coastal Range of Atacama Desert. [superscript 57]Fe Mössbauer spectroscopy was used for quantitative analysis of the degree of weathering of the meteorites, through the determination of the proportions of the various Fe-bearing phases and in particular the amount of oxidized iron in the terrestrial alteration products. The abundance of ferric ions in weathered chondrites can be related to specific precursor compositions and to the level of terrestrial weathering. The aim of the study was the identification, quantification and differentiation of the weathering products in the ordinary chondrites found in the San Juan area of Atacama Desert
MAJOR AND TRACE ELEMENTS AND OXYGEN ISOTOPES IN DIFFERENTIATED COSMIC SPHERULES RELATED TO VESTA-LIKE ASTEROIDS
Transantarctic Mountain microtektites: New petrographic data, water content, and Nd and Sr isotopic composition
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