946 resultados para 13200-032


Relevância:

100.00% 100.00%

Publicador:

Relevância:

100.00% 100.00%

Publicador:

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Within the framework of the EU-funded BENGAL programme, the effects of seasonality on biogenic silica early diagenesis have been studied at the Porcupine Abyssal Plain (PAP), an abyssal locality located in the northeast Atlantic Ocean. Nine cruises were carried out between August 1996 and August 1998. Silicic acid (DSi) increased downward from 46.2 to 213 µM (mean of 27 profiles). Biogenic silica (BSi) decreased from ca. 2% near the sediment-water interface to <1% at depth. Benthic silicic acid fluxes as measured from benthic chambers were close to those estimated from non-linear DSi porewater gradients. Some 90% of the dissolution occurred within the top 5.5 cm of the sediment column, rather than at the sediment-water interface and the annual DSi efflux was close to 0.057 mol Si/m**2/yr. Biogenic silica accumulation was close to 0.008 mol Si/m**2/yr and the annual opal delivery reconstructed from sedimentary fluxes, assuming steady state, was 0.065 mol Si/m**2/yr. This is in good agreement with the mean annual opal flux determined from sediment trap samples, averaged over the last decade (0.062 mol Si/m**2/yr). Thus ca. 12% of the opal flux delivered to the seafloor get preserved in the sediments. A simple comparison between the sedimentation rate and the dissolution rate in the uppermost 5.5 cm of the sediment column suggests that there should be no accumulation of opal in PAP sediments. However, by combining the BENGAL high sampling frequency with our experimental results on BSi dissolution, we conclude that non-steady state processes associated with the seasonal deposition of fresh biogenic particles may well play a fundamental role in the preservation of BSi in these sediments. This comes about though the way seasonal variability affects the quality of the biogenic matter reaching the seafloor. Hence it influences the intrinsic dissolution properties of the opal at the seafloor and also the part played by non-local mixing events by ensuring the rapid transport of BSi particles deep into the sediment to where saturation is reached.

Relevância:

60.00% 60.00%

Publicador:

Relevância:

60.00% 60.00%

Publicador:

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This series of research vignettes is aimed at sharing current and interesting research findings from our team of international Entrepreneurship researchers. In this vignette, Dr Martin Bliemel and his research team consider a trade-off entrepreneurs face when managing their network: should they form stronger relationships to acquire key resources, or should they reach out to more potential partners to access new resources?

Relevância:

20.00% 20.00%

Publicador:

Resumo:

BIM as a suite of technologies has been enabled by the significant improvements in IT infrastructure, the capabilities of computer hardware and software, the increasing adoption of BIM, and the development of Industry Foundation Classes (IFC) which facilitate the sharing of information between firms. The report highlights the advantages of BIM, particularly the increased utility and speed, better data quality and enhanced fault finding in all construction phases. Additionally BIM promotes enhanced collaborations and visualisation of data mainly in the design and construction phase. There are a number of barriers to the effective implementation of BIM. These include, somewhat paradoxically, a single detailed model (which precludes scenarios and development of detailed alternative designs); the need for three different interoperability standards for effective implementation; added work for the designer which needs to be recognised and remunerated; the size and complexity of BIM, which requires significant investment in human capital to enable the realisation of its full potential. There are also a number of challenges to implementing BIM. The report has identified these as a range of issues concerning: IP, liability, risks and contracts, and the authenticity of users. Additionally, implementing BIM requires investment in new technology, skills training and development of news ways of collaboration. Finally, there are likely to be Trade Practices concerns as requiring certain technology owned by relatively few firms may limit

Relevância:

20.00% 20.00%

Publicador:

Resumo:

“Infirmitas Christi”. La debilidad de Cristo en el comentario agustiniano de los Salmos / Héctor Aguer -- Recuperando la Teología de la vida espiritual. IIda Parte / Juan Carlos Leardi -- “Los evangelios de la infancia” en una reciente publicación de Raymond E. Brown / Jorge Mejía -- Notas bibliográficas -- Crónica de la Facultad -- Índice del volumen XV

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Fundo da Assembleia Nacional Constituinte 1987/88 - Câmara dos Deputados, Centro de Documentação e Informação, Coordenação de Arquivo.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Servicios registrales