4,113 research outputs found

    Deep-water bottom current dynamics: processes, products & challenges

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    Contourites are deep-water sedimentary deposits created under the influence of predominantly along-slope bottom currents. They are considered to be excellent deep-water recorders of global climatic change. Over the last decade, the improvement of deep-water survey technology enabled better visualising and understanding their driving processes, recognizing these deposits in more complex areas and in shallower depositional environments (such as shallow seas and lakes). Unfortunately, there still is no uniform and unequivocal classification, since the coupling between geological and hydrographic processes is rather vaguely defined due to the lack of good “in-situ” observations, in contrast to shallow marine and river systems. This paper aims to introduce the challenges and potential benefits that are ahead of us in contourite research, and aspires to open a dialogue between the deep and shallow water sediment dynamic communities

    Introduction

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    Bloodstream yeast infections: a 15-month survey

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    A 15-month survey of 412 bloodstream yeast isolates from 54 Belgian hospitals was undertaken. Candida albicans was the most common species (47.3%) followed by C. glabrata (25.7%), C. parapsilosis (8.0%), C. tropicalis (6.8%) and Saccharomyces cerevisiae (5.1%). Common predisposing factors were antibacterial therapy (45%), hospitalization in intensive care units (34%), presence of in-dwelling catheters (32%), underlying cancer (23%) and major surgery (11%). Most patients had more than one predisposing factor. Fluconazole alone or in combination with another antifungal agent was the treatment of choice for 86.6% of the cases. Susceptibility testing revealed that 93.5% were susceptible to amphotericin B, 39.6% to itraconazole, 42.8% to fluconazole and 87% to voriconazole. Resistance to azoles was more common among C. glabrata isolates

    Het mysterie van zee- en oceaanbodems

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    A high-resolution magnetic record of drift sediments in the neighbourhood of mound provinces in the Porcupine Seabight

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    The Porcupine Seabight forms a deep embayment in the Atlantic margin, off the south-western coast of Ireland. Very-high resolution seismic profiling, acquired since 1997, revealed the presence of large (carbonate) mounds.In general, the mounds are surrounded by bottom-current related deposits. The changes of seismic characteristics within the uppermost unit are interpreted as phases in a slope parallel drift under changing oceanographic conditions.The magnetic susceptibility records of two giant piston cores (MD01-2450 and MD01-2452), taken respectively in the drift sediments at the SE-flank of a Belgica mound (eastern flank of the basin) and above a Magellan mound (northern flank of the basin), were analysed in order to provide a relative time frame and to investigate possible changes in paleoceanography and paleoclimatology.Core MD01-2450 enabled us to propose a relative dating of over 74 ka, which has been confirmed by comparing the intensity of the NRM (Natural Remanent Magnetization) to ARM (Anhysteretic Remanent Magnetization) ratio with known intensity data. Another very remarkable observation in this core is the presence of iron sulfides between 630 and 1080 cm depth. This local iron sulfide enrichment could be the result of an anaerobic process with sulfate reduction during a period of non-steady-state diagenesis.Core MD01-2452, located in the sediments on top of the buried Magellan mounds, shows more pronounced paleoclimatological changes than the core located at the SE-flank of the Belgica mound. Moreover, typical HL can be recognized very clearly from magnetic susceptibility and P-wave velocity data during the latest glacial. The influence of European HE in the northern part of the basin could be less than on the eastern flank. However, we should be bear in mind that currents seem to be much weaker in the Magellan province than in the Belgica province. These weaker currents can be responsible for better preserved and thus more pronounced paleoclimatological and paleoceanographic changes in the uppermost quaternary sediment layers
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