The dynamical behaviour of shallow-marine dunes

In the period 1995-1999, a detailed morpho- and sediment dynamical investigation was carried out in the western Belgian near coastal area, in water depths of -3 to -15 m MLLWS. Through chronosequential bathymetrical and digital side-scan sonar registrations supplemented by intensive samplings, a quantitative monitoring of the most dynamic zones was accomplished. Although, the area is generally devoid of bedforms, well-constraint zones of very large dunes occur where the bed shear stresses are highest. Since, suspended load accounts for more than 80 %, the dimensions seem to be largely controlled by the amount of the total load actually taking part in bedform development. A clear differentiation exists between the morphology of the dunes and their surficial sediments, the troughs being up to 0.30 phi finer than the crests. During the observation period, the similarities in crestline positions were more striking than the differences and showed a maximum shift of only 20 m. The data set allowed to differentiate the vulnerability of the area to varying hydro-meteorological conditions and showed that the area recovers fairly quickly from stormy periods

Morphological evolution of the Kwinte Bank central depression before and after the cessation of aggregate extraction

Analyses of the records of ships registers and Electronic Monitoring Systems, of the trailer suction hopper dredgers, operating on the Belgian Continental Shelf, reveal that since the beginning of extraction in 1976, 75% of the total extracted volume originates from only one sandbank, the Kwinte Bank. At present, two morphologically-distinguished depressions are observed along the two most dredged areas of this sandbank: one in the central; and one in the northern part of the bank. In order to limit the impact of sand extraction on the bathymetry, the central depression of the Kwinte Bank was closed for exploitation, in February 2003. An understanding of the morphological evolution of this central depression is based upon data obtained: (a) from November 1999, until the closure for extraction in February 2003; and (b) on the subsequent post-dredging evolution, until June 2005. During this 5-year period, a total of 17 surveys were carried out with a multibeam echosounder over the area of the central depression (KBMA) and over a reference zone on an adjacent non-exploited sandbank. The resulting time-series of bathymetrical digital terrain models, together with backscatter strength maps, permit a detailed comparison of the bathy-morphological and sedimentary evolution of both of the monitored areas. Since the commencement of multibeam monitoring in 1999, an overall deepening (by 0.5m) of the entire KBMA monitoring zone is observed, until the cessation of dredging, in February 2003. Subsequently, the deepening slowed down and the variation in sediment volumes became similar to that of the adjacent non-exploited sandbank. From this, marine aggregate extraction appears to have only a local impact

Rarita-Schwinger Type Operators on Spheres and Real Projective Space

In this paper we deal with Rarita-Schwinger type operators on spheres and real projective space. First we define the spherical Rarita-Schwinger type operators and construct their fundamental solutions. Then we establish that the projection operators appearing in the spherical Rarita-Schwinger type operators and the spherical Rarita-Schwinger type equations are conformally invariant under the Cayley transformation. Further, we obtain some basic integral formulas related to the spherical Rarita-Schwinger type operators. Second, we define the Rarita-Schwinger type operators on the real projective space and construct their kernels and Cauchy integral formulas.Comment: 21 pages. arXiv admin note: text overlap with arXiv:1106.358

Investigation of the natural sand transport on the Belgian Continental shelf: BUDGET (<u>B</u>eneficial <u>u</u>sage of <u>d</u>ata and <u>g</u>eo-<u>e</u>nvironmental <u>t</u>echniques)

On the Belgian continental shelf (BCS), a variety of sediment dynamical studies have been performed both by governmental organisations and research institutions. Each study proposed to achieve a better insight in the sediment dynamical processes taking place on a specific spatial scale and during a particular time period. However, all these studies contain a piece of information, which contribute to the global sediment dynamical behaviour of the sediments of the BCS.In the course of the project, an overview has been produced of all these studies. Most of the data has been re-evaluated and the results were compiled in a synthesis map to characterise the natural sand transport on the Belgian continental shelf. The map indicates the general nature of the surficial sediments superimposed with the occurrence of larger bedforms. Additionally, areas are indicated where the thickness of the quaternary deposits is less than 2.5 mas these sediments might take part in the sediment transport process. To illustrate the hydrodynamics of the BCS, current ellipses have been selected based on modelling results on a 750 mgrid resolution and locations were indicated where current meter or other hydrodynamic data has been collected. Towards the directions of sediment transport, a variety of arrows are drawn whereby a distinction is made between transport vectors based on geo-environmental methods and those based on in-situ sediment transport measurements and on modelling results. If available, quantities are added uniformised in tonnes/m/day.The study also included a critical analysis of the data and methods used. The deduction of residual transport directions was evaluated on the basis of the asymmetry of bedforms, tracer experiments, sediment differentiation, current and suspended sediment concentration measurements and based on numerical sediment transport modelling. Evaluation criteria were set-up regarding the different space and time scales involved. The influence of hydro-meteorological conditions on the sediment dynamics was discussed.The results allowed defining gaps in the present knowledge and including recommendations for future research and propositions for an integrated research programme on the Belgian continental shelf. Main emphasis is put on an efficient mapping of the seafloor including the set-up of an automated characterisation of seabed sediments albeit combined with a suitable sampling strategy. Regarding hydrodynamical and sand transport measurements, the development of a multi-sensor bottom frame is recommended including a realistic quantification of sediment fluxes through the water column.To enhance the efficiency and practical use of seabed data, the set-up of an overall Geographical Information System (GIS) is highly recommended including guidelines and protocols on the prerequisites of mapping and sampling projects since this would largely facilitate the set-up and evaluation of environmental impact assessments. The project largely benefited from contributions from foreign researchers from France, England and the Netherlands

The Glasgow Voice Memory Test: Assessing the ability to memorize and recognize unfamiliar voices

One thousand one hundred and twenty subjects as well as a developmental phonagnosic subject (KH) along with age-matched controls performed the Glasgow Voice Memory Test, which assesses the ability to encode and immediately recognize, through an old/new judgment, both unfamiliar voices (delivered as vowels, making language requirements minimal) and bell sounds. The inclusion of non-vocal stimuli allows the detection of significant dissociations between the two categories (vocal vs. non-vocal stimuli). The distributions of accuracy and sensitivity scores (d’) reflected a wide range of individual differences in voice recognition performance in the population. As expected, KH showed a dissociation between the recognition of voices and bell sounds, her performance being significantly poorer than matched controls for voices but not for bells. By providing normative data of a large sample and by testing a developmental phonagnosic subject, we demonstrated that the Glasgow Voice Memory Test, available online and accessible fromall over the world, can be a valid screening tool (~5 min) for a preliminary detection of potential cases of phonagnosia and of “super recognizers” for voices

All quiet on the sea bottom front? Lessons from the morphodynamic monitoring

The impact of the construction of the offshore wind farms on the turbidity was local and temporary, with no significant difference between the before and after situation. Erosion pits were formed, both around gravity based foundations and monopiles, though erosion protection provided the necessary stability. Dredging/filling works were more complex than expected. Large volumes of sand were lost and sand pits did not refill naturally. In dune migrating areas the coverage of export cables could not be guaranteed. As a result they are now buried 1 m below the base of the dunes

Ideal versus corrected body weight for dosage of sugammadex in morbidly obese patients

Summary To date, the dosing of sugammadex is based on real body weight without taking fat content into account. We compared the reversal of profound rocuronium-induced neuromuscular blockade in morbidly obese patients using doses of sugammadex based on four different weight corrections. One hundred morbidly obese patients, scheduled for laparoscopic bariatric surgery under propofolsufentanil anaesthesia, were randomly assigned four groups: ideal body weight; ideal body weight + 20%; ideal body weight + 40%; and real body weight. Patients received sugammadex 2 mg.k