Grain-size trend analysis for the determination of non-biogenic sediment transport pathways on the Kwinte Bank (southern North Sea), in relation to sand dredging

Grain-size trend analysis is applied to the determination of sediment transport pathways over the Kwinte Bank, southern North Sea; which had been subjected to intensive dredging, within the context of the environmental impact of dredging activities. On the basis of the results of grain-size trend analysis, focused mainly upon the transportation of the non-biogenic sedimentary material (<2 mm), it appears that: (i) there is a main sediment pathway over the western (bank crest) and central (dredged area) part of the bank directed toward the NE; whilst a secondary pathway is established over its eastern gently-sloping flank, having a SE direction. Further, the present analysis shows that the area of the central (dredged) depression acts more as a ‘by-passing’ zone rather than as a depo-centre for the nonbiogenic sediments. Comparison undertaken with the results of an earlier investigation, for a non-dredged area at the northern end of the same bank, reveals that the depression due to dredging modifies significantly the sediment transport pathways; this may be attributed to a change in the seabed morphology which, in turn, modifies the nearbed hydrodynamics (related to tide and/or storm events)

Le traitement des eaux usées

L'article présente brièvement l'état de l'épuration des effluents des collectivités en France et au Québec. Il souligne ensuite quelques changements importants intervenus depuis dix ans dans le monde grâce aux progrès de la recherche et qui pourraient marquer l'avenir.En France, 95 % des agglomérations de plus de 10 000 équivalents-habitants disposent d'une station d'épuration. Le rythme de construction a atteint 730 installations nouvelles dans l'année 1976 mais il est redescendu à moins de 300/an. Sur les 11 310 stations de plus de 200 équivalents-habitants recensées, 5 % réalisent seulement un traitement primaire et la moitié en nombre, représentant plus de 60 % de la capacité de traitement utilisent le procédé des boues activées.Les investissements à réaliser entre 1994 et 2005 pour satisfaire aux exigences de la directive européenne du 21 mai 1991 sont évalués à environ 36 milliards de francs français, correspondant à la création de capacités de traitement supplémentaires de 17 millions d'équivalents-habitants et à des améliorations plus ou moins importantes d'un grand nombre de stations existantes.Au Québec, la construction des stations d'épuration s'est faite essentiellement dans les années 80 et 90. Aujourd'hui, près de 80 % de la population est desservie par des installations d'épuration, soit environ 4,9 millions d'habitants pour un débit hydraulique de 5,3 millions de m3/j.Parmi les 450 ouvrages municipaux ceux des Communautés Urbaines de Montréal et de Québec représentent, à eux seuls, près de 60 % de la capacité installée.Les stations physico-chimiques, bien que peu nombreuses, sont les plus importantes (6 stations pour 2,28 millions d'habitants) suivies par les boues activées (40 stations pour 0,69 million d'habitants) et la biofiltration (9 stations pour 0,75 million d'habitants). Environ 320 stations, de dimension plus modeste utilisent des étangs aérés, desservant en moyenne une population de 3 500 habitants.Sur le plan de l'évolution des techniques, la décennie écoulée a vu apparaître ou se confirmer des évolutions qui marqueront sans doute profondément la conception et l'exploitation des stations d'épuration dans les années à venir : - l'objectif maintenant presque généralisé d'éliminer les nutriments azote et phosphore et le développement rapide des techniques correspondantes;- la prise de conscience de l'importance des flux polluants véhiculés par les eaux pluviales et un début d'adaptation des stations d'épuration;- le développement limité mais réel des traitements anaérobies qui ont survécu à la démobilisation des surlendemains de la crise énergétique;- le fort développement des systèmes d'épuration biologique à culture fixée et notamment des biofiltres;- l'apparition prometteuse des membranes dans les systèmes d'épuration biologique permettant d'envisager de nouveaux objectifs de traitement;- la prise en compte de la fiabilité des systèmes d'épuration avec un poids de plus en plus important par rapport aux performances de pointe- une vision plus intégrée de la prévention des pollutions tant dans l'industrie (technologies propres) que dans les agglomérations (gestion intégrée de l'ensemble réseau-station d'épuration).This paper provides a brief discussion of the state of municipal wastewater treatment in France and Quebec. It then presents some important changes that have developed over the last ten years in the world and their potential influence on the future.In France, 95% of towns of more than 10 000 residents have a wastewater treatment plant. Construction of new plants reached 730 installations in 1976, but has since declined to less than 300/year. Among 11 310 sites of more of 200 inhabitants, 5 % utilize only primary treatment and 50 % utilize the activated sludge process which represents 60 % of the treatment capacity.In order to satisfy the European directive of May 21st 1991, approximately 36 billion French Francs should be invested between 1994 and 2005. This investment represents new wastewater treatment facilities for 17 million people.In Quebec, construction of wastewater treatment plants occurred mainly during the 80's and 90's. Today, nearly 80 % of the population is served by wastewater treatment plants, which represent approximately 4,9 million residents. This accounts for a flow rate of 5,3 million cubic meters per day.Among 450 municipal treatment plants, those of the urban communities of Montreal and Quebec represent nearly 60 % of the total wastewater treatment capacity of Quebec.Physico-chemical treatment plants are the most significant (6 plants for 2,28 million residents) followed by activated sludge process plants (40 plants for 0,69 million residents) and plants using biofilter technologies (9 plants for 0,75 million residents). A total of approximately 320 small treatment plants, serving an average of 3 500 residents, use the aerated lagoon treatment.Over the past decade technological developments have resulted in an evolution that will modify the design and operation of wastewater treatment plants in the future:- the more widespread use of techniques developed for the elimination of nitrogen and phosphorus; - the realization of the importance of polluting charges transported by pluvial waters; the beginning of the resultant wastewater treatment plant adaptations; - the limited development of anaerobic treatments that have survived the energy crisis; - the valuable development of biological fixed-culture systems for wastewater treatment and most notably, the biofilters; - the appearance of promising membrane technology in wastewater treatment systems, which could facilitate the definition of new treatment objectives; - the consideration the global reliability of the wastewater treatment systems instead of only peak performance; - a more integrated vision for the prevention of pollution in industry (clean technologies) as well as in the domestic environment (integrated management of sewerage system and wastewater treatment plant

Biological characteristics of orthopaedic implant surfaces

Výměna kyčelního a kolenního kloubu představuje neodmyslitelnou část ortopedie. S narůstajícím počtem primárních operací ovšem narůstá také počet pooperačních komplikací. Nejčastějším důvodem je hluboká infekce totální kloubní náhrady, která patří k nejobtížněji řešitelným komplikacím této jinak velmi úspěšné operace. První část této práce se zabývala stanovením primární odolnosti 14-ti typů nejčastěji užívaných alopatických materiálů, resp. jejich povrchových úprav vůči bakteriální kolonizaci mikrobiálními agens (Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, Enterococcus faecalis a Escherichia coli). Studované materiály zahrnovaly kovové slitiny na bázi CoCrNo, FeNiCr a Ti6A14V aplikované pro nosné části implantátu; dále polymerní a keramické materiály reprezentované ultravysokomolekulárním polyethylenem (UHMWPE) a oxidem hlinitým (Al2O3) využívané na konstrukce kluzných částí. Cílem bylo stanovení relací mezi povrchovou drsností a citlivosti vůči kolonizaci bakteriálními agens pro daný typ materiálu a dále sledování chování jednotlivých mikrobiálních agens na různých materiálech a posouzení jejich afinity k danému typu materiálu. Bylo zjištěno, že drsnost povrchu je určujícím faktorem při tvorbě biofilmu bez ohledu na typ materiálu v případech kmenů E. coli,...Total hip and knee arthroplasty surgeries form an integral part of orthopaedic practice. With an increase of the primary arthroplasty surgeries performed, comes also an increase in the number of complications. The most common complications of these otherwise very successful procedures is periprosthetic joint infections which are also one of the most difficult to treat. In the first part of the study, we evaluated the primary bacterial resistance of the 14 most commonly used materials in the construction of joint prostheses. More specifically, we concentrated on how their surface treatment resists colonisation by specific bacterial species (Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, Enterococcus faecalis and Escherichia coli). The studied materials included metal alloys that are commonly used in the weight bearing parts of implants - CoCrNo, FeNiCr and Ti6A14V - but also polymeric and ceramic materials used in the bearing materials, represented by ultra-high- molecular-weight polyethylene (UHMWPE) and aluminium oxide (Al2O3). Our aim was to assess the relationship between material surface roughness and the sensitivity to colonisation by specific bacterial strains and to evaluate their affinity to different materials. Previous studies have proven that the roughness of...1st Department of Orthopaedics First Faculty of Medicine and University Hospital MotolI. ortopedická klinika 1. LF UK a FN Motol1. lékařská fakultaFirst Faculty of Medicin

Delayed postural control during self-generated perturbations in the frail older adults

International audiencePurpose: The aim of this study was to investigate the coordination between posture and movement in pathological aging (frailty) in comparison with normal aging, with the hypothesis that in pathological aging, postural control evolves towards a more reactive mode for which the perturbation induced by the movement is not anticipated and leads to delayed and late postural adjustments. Methods: Elderly subjects performed rapid focal arm-raising movements towards a target, from an upright standing position in two stimuli conditions: simple reaction time and choice reaction time (CRT). Hand and center of pressure (CoP) kinematics were compared between a control group and a frail group of the same age. Results: In frail individuals, the entire movement was impaired and slowed down. In addition, postural adjustments that classically precede and accompany the focal arm movement were delayed and reduced, especially in the CRT condition in which the motor prediction is more limited. Finally, a correlation between the time to CoP maximal velocity and the timed up-and-go score was observed. Conclusion: In these patients, it was concluded that the control of the CoP displacement evolved from a proactive mode in which the perturbation associated with the arm movement is anticipated toward a more reactive mode in which the perturbation is compensated by late and delayed adjustments

Voluntary imitation in alzheimer's disease patients

Although Alzheimer's disease (AD) primarily manifests as cognitive deficits, the implicit sensorimotor processes that underlie social interactions, such as automatic imitation, seem to be preserved in mild and moderate stages of the disease, as is the ability to communicate with other persons. Nevertheless, when AD patients face more challenging tasks, which do not rely on automatic processes but on explicit voluntary mechanisms and require the patient to pay attention to external events, the cognitive deficits resulting from the disease might negatively affect patients' behavior. The aim of the present study was to investigate whether voluntary motor imitation, i.e., a volitional mechanism that involves observing another person's action and translating this perception into one's own action, was affected in patients with AD. Further, we tested whether this ability was modulated by the nature of the observed stimulus by comparing the ability to reproduce the kinematic features of a human demonstrator with that of a computerized-stimulus. AD patients showed an intact ability to reproduce the velocity of the observed movements, particularly when the stimulus was a human agent. This result suggests that high-level cognitive processes involved in voluntary imitation might be preserved in mild and moderate stages of AD and that voluntary imitation abilities might benefit from the implicit interpersonal communication established between the patient and the human demonstrator

European marine aggregates resources: Origins, usage, prospecting and dredging techniques

Marine aggregates (sand and gravel) are important mineral resources and traded commodities. Their significance is bound to increase further, due to increasing coastal zone development, stricter environmental regulation concerning land-won aggregates and increasing demand for beach replenishment material. Marine aggregate (MA) deposits can be differentiated into relict and modern deposits. The former consist of sedimentary material deposited in the past and under different environmental and sedimentary regimes than those existing presently (e.g. the gravel/ sand deposits of the Pleistocene buried river valleys of the northwestern European shelves). The latter are deposits, which have been formed and controlled by the modern hydro-and sediment dynamic conditions (e.g. the linear sand banks of the southern North Sea). The present contribution reviews the current state of affairs in 9 representative European Member States concerning the prospecting and extraction (dredging) techniques as well as the levels of production and usage. The review has shown a mixed record as, in some of the studied States, marine aggregate production is an important and streamlined activity, whereas other States have not yet developed efficient marine aggregate policies and industries. It has also shown that although attempts have been lately made to coordinate the field, the industry still faces problems, which hinder its sustainable development. These include (amongst others): lack of standardisation of the relevant information, difficulties in the access to information, non-coherent regulatory regimes and limited collaboration/coordination between the marine scientific research establishments and the marine aggregate industry. These issues should be addressed as quickly as possible in order to exploit effectively this important mineral resource

Un colloque sur la pluridisciplinariaté dans les problèmes d'environnement : quelques enseignements et orientations pour l'avenir

International audienceAn experiment has been carried out in Rennes (Brittany, West of France) in June 2000 to estimate atrazine and alachlor volatilisation fluxes after application over a maize crop. Fluxes were calculated using the classical aerodynamic micrometeorological method from vertical gradients of pesticide concentrations, temperature and wind speed. Volatilisation fluxes showed a diurnal pattern of the order of few ng/m2/s for atrazine and the order of a few 10 ng/m2/s for alachlor, leading to cumulated losses of approximately 0.1% of the theoretical application dose for atrazine and several-fold of that in the case of alachlor

Proceedings European Geothermal Congress

ABSTRACT As of today most of geothermal projects and the related feasibility studies have been realized on the basis of geological, 2D-seismic and hydrogeological data interpretation without considering the petrophysical and geomechanical properties at the micro scale. In this paper we want to point out the primary role of petrophysics in the reservoir analysis for a right identification of the structural lineaments and flow lines, to optimize the thermal efficiency of a geothermal project finalized to decrease the risk and the costs