858 resultados para National Child Abuse and Neglect Data System.
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no.84 (1987:Sept.)
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no.112 (1988)
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no.99 (1988:Jan.)
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Among many other problems, the migration, humanitarian and policy crises in the European Union in 2015 and early 2016 have highlighted a pressing need for reliable, timely and comparable statistical data on migration, asylum and arrivals at national borders. In this fast-moving policy field, data production and the timeliness of dissemination have seen some improvements but the sources of data remain largely unchanged at national level. In this paper the author examines the reasons for some of the problems with the data for policy and for public discussion, and makes a set of recommendations that call for a complete and updated inventory of data sources and for an evaluation of the quality of data used for policy-making.
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Hydrogen isotope values (dD) of sedimentary terrestrial leaf wax such as n-alkanes or n-acids have been used to map and understand past changes in rainfall amount in the tropics because dD of precipitation is commonly assumed as the first order controlling factor of leaf wax dD. Plant functional types and their photosynthetic pathways can also affect leaf wax dD but these biological effects are rarely taken into account in paleo studies relying on this rainfall proxy. To investigate how biological effects may influence dD values we here present a 37,000-year old record of dD and stable carbon isotopes (d13C) measured on four n-alkanes (n-C27, n-C29, n-C31, n-C33) from a marine sediment core collected off the Zambezi River mouth. Our paleo d13C records suggest that each individual n-alkanes had different C3/C4 proportional contributions. n-C29 was mostly derived from a C3 dicots (trees, shrubs and forbs) dominant vegetation throughout the entire record. In contrast, the longer chain n-C33 and n-C31 were mostly contributed by C4 grasses during the Glacial period but shifted to a mixture of C4 grasses and C3 dicots during the Holocene. Strong correlations between dD and d13C values of n-C33 (correlation coefficient R2 = 0.75, n = 58) and n-C31 (R2 = 0.48, n = 58) suggest that their dD values were strongly influenced by changes in the relative contributions of C3/C4 plant types in contrast to n-C29 (R2 = 0.07, n = 58). Within regions with variable C3/C4 input, we conclude that dD values of n-C29 are the most reliable and unbiased indicator for past changes in rainfall, and that dD and d13C values of n-C31 and n-C33 are sensitive to C3/C4 vegetation changes. Our results demonstrate that a robust interpretation of palaeohydrological data using n-alkane dD requires additional knowledge of regional vegetation changes from which nalkanes are synthesized, and that the combination of dD and d13C values of multiple n-alkanes can help to differentiate biological effects from those related to the hydrological cycle.
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Acoustic and pelagic trawl data were collected during various pelagic surveys carried out by IFREMER in May between 2000 and 2012 (except 2001), on the eastern continental shelf of the Bay of Biscay (Pelgas series). The acoustic data were collected with a Simrad EK60 echosounder operating at 38 kHz (beam angle at -3 dB: 7°, pulse length set to 1.024 ms). The echosounder transducer was mounted on the vessel keel, at 6 m below the sea surface. The sampling design were parallel transects spaced 12 nm apart which were orientated perpendicular to the coast line from 20 m to about 200 m bottom depth. The nominal sailing speed was 10 knots and 3 knots on average during fishing operations. The scrutinising (species identification) of acoustic data was done by first characterising acoustic schools by type and then linking these types with the species composition of specific trawl hauls. The data set contains nautical area backscattering values, biomass and abundance estimates for blue whiting for one nautical mile long transect lines. Further information on the survey design, scrutinising and biomass estimation can be found in Doray et al. 2012.
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During the Paleocene-Eocene Thermal Maximum (PETM) about 56 million years ago, thousands of petagrams of carbon were released into the atmosphere and ocean in just a few thousand years, followed by a gradual sequestration over approximately 200,000 years. If silicate weathering is one of the key negative feedbacks that removed this carbon, a period of seawater calcium carbonate saturation greater than pre-event levels is expected during the event's recovery phase. In marine sediments, this should be recorded as a temporary deepening of the depth below which no calcite is preserved - the calcite compensation depth (CCD). Previous and new sedimentary records from sites that were above the pre-PETM calcite compensation depth show enhanced carbonate accumulation following the PETM. A new record from an abyssal site in the North Atlantic that lay below the pre-PETM calcite compensation depth shows a period of carbonate preservation beginning about 70,000 years after the onset of the PETM, providing the first direct evidence for an over-deepening of the calcite compensation depth. This record confirms an overshoot in ocean carbonate saturation during the PETM recovery. Simulations with two earth system models support scenarios for the PETM that involve both a large initial carbon release followed by prolonged low-level emissions, consistent with the timing of CCD deepening in our record. Our findings indicate that sequestration of these carbon emissions was most likely the result of both globally enhanced calcite burial above the calcite compensation depth and, at least in the North Atlantic, by a temporary over-deepening of the calcite compensation depth.
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Includes bibliographies.
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Mode of access: Internet.
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National Highway Traffic Safety Administration, Washington, D.C.
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Mode of access: Internet.
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National Highway Traffic Safety Administration, Washington, D.C.
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National Highway Traffic Safety Administration, Washington, D.C.
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Cover title.
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Shipping list no.: 95-0031-P.
