999 resultados para ba


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This geochemical investigation utilizes Ba/Ca in the benthic foraminifer Cibicides wuellerstorfi from cores taken from the Bahama Banks and the Caribbean Sea to reconstruct changes in basal thermocline ventilation (800-1000 m) and middepth thermohaline circulation (1000-2000 m) in the western North Atlantic during the last glacial period, focusing on the deglacial transition. Previous studies show that an increase in ventilation of the North Atlantic subtropical gyre during the Last Glacial Maximum (LGM) caused a 30-60% decrease in labile nutrients within the thermocline layer. Using foraminiferal Ba/Ca as a proxy of refractory nutrients, increased ventilation during the LGM produced a depletion of less than 20% compared to Holocene values. Following glaciation, the production of Glacial North Atlantic Intermediate Water (GNAIW) shut down owing to the presence of meltwater in the surface ocean, which resulted in a decrease in ventilation, as seen by an enrichment of barium in the basal thermocline. GNAIW was subsequently replaced by barium-rich southern component water in the middepth western North Atlantic. Foraminiferal Ba/Ca data suggest a 38% contribution from southern component water to a depth as shallow as 1475 m and a 14% contribution at 1123 m during deglaciation.

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Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

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O presente trabalho surge no âmbito do mestrado em Ciências da Educação - Especialização em Utilização Pedagógica das Tecnologias da Informação e Comunicação, da Escola Superior e Ciências Sociais do Instituto Politécnico de Leiria, no ano lectivo 2013/2014. Seguindo uma metodologia qualitativa, de índole descritiva e exploratória, procurámos estudar as interações entre pares e adultos aquando da utilização do software educativo “O Meu Baú dos Brinquedos” (Faria, P. & Faria, C., 2001) – software vencedor do XI Concurso Nacional de Software Educacional, no âmbito do programa Nónio Século XXI. Para a realização deste estudo, contámos com a participação de duas crianças de 5 anos do Jardim de Infância da rede pública de Oliveira do Hospital que, ao longo de 2 sessões, interagiram entre si e com a investigadora aquando da utilização do software em análise. Recorrendo ao registo videográfico, sua transcrição e posterior análise de conteúdo foi possível inferir que o software em estudo poderá estimular a interação entre pares (principalmente através da comunicação não verbal), promovendo o desenvolvimento e a aprendizagem de crianças ao nível da área de comunicação e expressão do domínio da matemática (Ministério da Educação, 1997a), nomeadamente na discussão de atividades e na resolução de problemas. Estes dados, ainda que exploratórios, darão indicações sobre o potencial pedagógico dos videojogos / softwares educativos para a educação pré-escolar.

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Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

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Lead isotopic compositions and Pb and Ba concentrations have been measured in ice cores from Law Dome, East Antarctica, covering the past 6500 years. 'Natural' background concentrations of Pb (ab. 0.4 pg/g) and Ba (ab. 1.3 pg/g) are observed until 1884 AD, after which increased Pb concentrations and lowered 206Pb/207Pb ratios indicate the influence of anthropogenic Pb. The isotopic composition of 'natural' Pb varies within the range 206Pb/207Pb=1.20-1.25 and 208Pb/207Pb=2.46-2.50, with an average rock and soil dust Pb contribution of 8-12%. A major pollution event is observed at Law Dome between 1884 and 1908 AD, elevating the Pb concentration four-fold and changing 206Pb/207Pb ratios in the ice to ab. 1.12. Based on Pb isotopic systematics and Pb emission statistics, this is attributed to Pb mined at Broken Hill and smelted at Broken Hill and Port Pirie, Australia. Anthropogenic Pb inputs are at their greatest from 1900 to 1910 and from ab. 1960 to ab. 1980. During the 20th century, Ba concentrations are consistently higher than 'natural' levels and are attributed to increased dust production, suggesting the influence of climate change and/or changes in land coverage with vegetation.

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Pb and Ba concentrations and Pb isotopic compositions are reported for firn core and snow pit samples from Victoria Land, Antarctica, dating from 1872 AD to 1994 AD. From variations in Pb/Ba ratios and Pb isotopic compositions, two periods of major Pb enhancements were identified, from 1891 to 1908 AD and from 1948 to 1994 AD. The earlier pollution event is attributed to Pb emissions from non-ferrous metal production and coal combustion in the Southern Hemisphere and is in excellent agreement with coincident pollution inputs reported in firn/ice cores from two other regions of Antarctica, at Coats Land and Law Dome. Using Pb isotopic systematics, it was calculated that ~50% of Pb deposited in Victoria Land in 1897 originated from anthropogenic emission sources. The more recent period of Pb enhancements, from 1948 to 1994 AD, corresponds to the introduction and widespread use of gasoline alkyl Pb additives in automobiles in the Southern Hemisphere, with anthropogenic Pb inputs averaging 60% of total Pb but with large uncertainty. Intra- and inter-annual variations in Pb concentrations and isotopic compositions were evaluated in snow pits samples corresponding to the period 1991-1994. Substantial variations in Pb/ Ba and 206Pb/207Pb ratios were detected but the absence of a regular seasonal pattern for these parameters suggests that the transport and deposition of aerosols to the Antarctic ice sheet are complex and vary from year to year.

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A record of Pb isotopic compositions and Pb and Ba concentrations are presented for the EPICA Dome C ice core covering the past 220 ky, indicating the characteristics of dust and volcanic Pb deposition in central East Antarctica. Lead isotopic compositions are also reported in a suite of soil and loess samples from the Southern Hemisphere (Australia, Southern Africa, Southern South America, New Zealand, Antarctica) in order to evaluate the provenance of dust present in Antarctic ice. Lead isotopic compositions in Dome C ice support the contention that Southern South America was an important source of dust in Antarctica during the last two glacial maxima, and furthermore suggest occasional dust contributions from local Antarctic sources. The isotopic signature of Pb in Antarctic ice is altered by the presence of volcanic Pb, inhibiting the evaluation of glacial-interglacial changes in dust sources and the evaluation of Australia as a source of dust to Antarctica. Consequently, an accurate evaluation of the predominant source(s) of Antarctic dust can only be obtained from glacial maxima, when dust-Pb concentrations were greatest. These data confirm that volcanic Pb is present throughout Antarctica and is emitted in a physical phase that is free from Ba, while dust Pb is transported within a matrix containing Ba and other crustal elements.

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Extremely broad emission wings at Hβ and Hα have been found in VLT-FLAMES Tarantula Survey data for five very luminous BA supergiants in or near 30 Doradus in the Large Magellanic Cloud. The profiles of both lines are extremely asymmetrical, which we have found to be caused by very broad diffuse interstellar bands (DIBs) in the longward wing of Hβ and the shortward wing of Hα. These DIBs are well known to interstellar but not to many stellar specialists, so that the asymmetries may be mistaken for intrinsic features. The broad emission wings are generally ascribed to electron scattering, although we note difficulties for that interpretation in some objects. Such profiles are known in some Galactic hyper/supergiants and are also seen in both active and quiescent Luminous Blue Variables (LBVs). No prior or current LBV activity is known in these 30 Dor stars, although a generic relationship to LBVs is not excluded; subject to further observational and theoretical investigation, it is possible that these very luminous supergiants are approaching the LBV stage for the first time. Their locations in the HRD and presumed evolutionary tracks are consistent with that possibility. The available evidence for spectroscopic variations of these objects is reviewed, while recent photometric monitoring does not reveal variability. A search for circumstellar nebulae has been conducted, with an indeterminate result for one of them.

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Syftet med denna studie var att undersöka hur medarbetarna på BA (fiktivt namn) upplever organisationens interna Employer Branding-arbete samt att belysa de aspekter som eventuellt skiljer strategi mot upplevelse. Det gjordes ett målinriktat urval av organisation medan valet av deltagare var ett slumpmässigt urval vilket resulterade i åtta respondenter (n= 8). Studien var en kvalitativ fallstudie med ett psykologiskt angreppssätt och innehöll en ostrukturerad intervju som tillsammans med dokumentation utgjorde intervjuguiden för den primära datainsamlingen genom åtta semistrukturerade intervjuer med medarbetarna. Fördelningen av urvalet var fyra kvinnor och fyra män med varierade yrkesroller inom en bemanningsdivision. Både den ostrukturerade intervjun och de semistrukturerade intervjuerna analyserades med hjälp av analysmetoden tematisk analys. Studiens resultat visade att BA:s interna Employer Branding och medarbetarnas upplevelser i stora drag överensstämde. Värderingar och interna karriärmöjligheter var centrala aspekter som både organisationen och respondenterna belyste. 

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An algorithm based on a Bayesian network classifier was adapted to produce 10-day burned area (BA) maps from the Long Term Data Record Version 3 (LTDR) at a spatial resolution of 0.05° (~5 km) for the North American boreal region from 2001 to 2011. The modified algorithm used the Brightness Temperature channel from the Moderate Resolution Imaging Spectroradiometer (MODIS) band 31 T31 (11.03 μm) instead of the Advanced Very High Resolution Radiometer (AVHRR) band T3 (3.75 μm). The accuracy of the BA-LTDR, the Collection 5.1 MODIS Burned Area (MCD45A1), the MODIS Collection 5.1 Direct Broadcast Monthly Burned Area (MCD64A1) and the Burned Area GEOLAND-2 (BA GEOLAND-2) products was assessed using reference data from the Alaska Fire Service (AFS) and the Canadian Forest Service National Fire Database (CFSNFD). The linear regression analysis of the burned area percentages of the MCD64A1 product using 40 km × 40 km grids versus the reference data for the years from 2001 to 2011 showed an agreement of R2 = 0.84 and a slope = 0.76, while the BA-LTDR showed an agreement of R2 = 0.75 and a slope = 0.69. These results represent an improvement over the MCD45A1 product, which showed an agreement of R2 = 0.67 and a slope = 0.42. The MCD64A1, BA-LTDR and MCD45A1 products underestimated the total burned area in the study region, whereas the BA GEOLAND-2 product overestimated it by approximately five-fold, with an agreement of R2 = 0.05. Despite MCD64A1 showing the best overall results, the BA-LTDR product proved to be an alternative for mapping burned areas in the North American boreal forest region compared with the other global BA products, even those with higher spatial/spectral resolution

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In the paper, I make references to the psychological process of passing from childhood to adulthood. In contemporary times, this process is spread in time, its boundaries are blurry and it is difficult to find in it the primordial initiation rituals known among primitive tribes. I call these phenomena the Sleeping Beauty syndrome, and compare the contemporary rites of passage from childhood to adulthood to this very fairy tale, in particular to its psychological readings. The theoretical framework for my considerations is based on a selection of anthropological rite concepts and elements of methodological concepts of studying fairy tales, such as structural and psychoanalytical approaches. My psychopedagogical analysis of the Sleeping Beauty fairy tale through the category rite of passage thus begins with defining this category underlining the possibility of using it in various sciences and referring to the fairy tale as a contemporary space for ritual initiation experience.