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571.
572.
Two kinds of regional disparities can be distinguished in Belgium. First there is the internationally well‐known dispute between Flanders and Wallonia. Secondly, there are large disparities within the regions. Three policy levels deal with these disparities: the (Flemish) regional level, the national government level and the EEC level. The purpose of this paper is to sketch the regional problems in Belgium, to analyse the policies that deal with them, to consider the co‐ordination problems between them and to shed some light on the public choice aspects of government interventions. It is concluded that regional policy in Belgium is a highly politicised affair. Furthermore public attention paid to regional policies has outgrown the importance of our regional disparities. Even other forms of micro‐economic policy are jeopardised by regional disparities and the resulting pressure. 相似文献
573.
In 1984, 115 samples of the starfish Asterias rubens L. collected in the south-eastern part of Cadet Trench (Mecklenburg Bay/Western Baltic Sea) were analyzed for their contents of a few major (calcium, magnesium) and trace elements (cadmium, copper, iron, mercury, manganese, nickel, lead, selenium and zinc). Distinct differences were found between starfish from different stations, and these are attributed to the composition of the sediments acting as a substrate for their prey (mussels, snails). Except for cadmium, the concentrations of the elements studied all correlated negatively with the diameter and weight of the starfish.
Parallel analyses of starfish arms and the central discs of the same animals showed that iron, zinc, copper and mercury levels were 16 to 30% higher, and selenium, manganese, magnesium, calcium and lead were 4 to 9% higher in the arms. Cadmium concentrations were 20% higher in the central discs than in the arms.
Stock estimations (about 52,000 tons fresh weight) show that starfish play a significant role in the benthic ecosystem of the western Baltic Sea. They can consume up to 200,000 tons of mussels and clams (Mytilus edulis, Macoma baltica) a year and may therefore represent a notable factor in the trace metal balance of the region. 相似文献
Parallel analyses of starfish arms and the central discs of the same animals showed that iron, zinc, copper and mercury levels were 16 to 30% higher, and selenium, manganese, magnesium, calcium and lead were 4 to 9% higher in the arms. Cadmium concentrations were 20% higher in the central discs than in the arms.
Stock estimations (about 52,000 tons fresh weight) show that starfish play a significant role in the benthic ecosystem of the western Baltic Sea. They can consume up to 200,000 tons of mussels and clams (Mytilus edulis, Macoma baltica) a year and may therefore represent a notable factor in the trace metal balance of the region. 相似文献
574.
A. van der Veen A. P. Grootjans J. de Jong J. Rozema 《Journal of Coastal Conservation》1997,3(1):71-78
This study reports on a primary succession on a beach plain on the Dutch Wadden island of Schiermonnikoog. Vegetation succession started in 1959 when a sand dike was constructed to prevent structural erosion of the area by storm floods. Since then the sandy beach behind the dike has been protected from the direct influence of the North Sea. Heavy storms in 1972, however, created a large gap in the dike which has remained open since. Occasional storm floods during winter penetrate deeply into the area and salt water can cover parts of the beach plain for several months. This had a pronounced impact on the vegetation. Vegetation maps for six different years and data from a permanent plot have been used to reconstruct vegetation succession over a 42-yr period. Certain parts of the area seem to have changed little, while others have developed a grassland or scrub cover. The heavy storms and associated processes such as sand blowing, intensive flooding and increased salinity have created a disturbance/stress gradient of progressive and regressive succession across the beach plain. In certain places the vegetation cover has repeatedly been destroyed and succession re-initiated. It is concluded that the different stages of succession and associated diversity of plant species only can persist through the maintenance of the natural dynamics of the area. 相似文献
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578.
Acetylcholinesterase (AChE) gel electrophoresis was performed on samples of amniotic fluid and extraembryonic coelomic fluid obtained by high resolution transvaginal ultrasound-guided amniocentesis from 38 women between 8 and 12 weeks of pregnancy. AChE was positive in 33 per cent (12/36) of the amniotic fluid samples; the percentage of positive results decreased as gestation advanced. AChE was positive in 32 per cent (9/28) of the extraembryonic coelomic fluid samples. In 81 per cent (21/26) of matched samples, the AChE results were identical in the two fluids. Amniotic fluid and extraembryonic coelomic fluid AChE electrophoresis cannot be used to diagnose neural tube defects prior to 12 weeks of gestation. 相似文献
579.
580.
Twenty stomiatoid fish larvae (3.1 to 21,9 mm) belonging to the genera Bathophilus, Cyclothone, and Stomias were collected in plankton nets from surface waters over depths of 3 to 4 m from Biscayne Bay, Florida, USA. The adults are mesopelagic in the open water of the Florida Current and, therefore, these larvae were presumably advected in parcels of high salinity water into the shallows of Biscayne Bay by winds, tides, or currents. The presence of these larvae suggest that sewage discharged into the Florida Current may be recycling into coastal waters as well as into Biscayne Bay.Scientific Contribution No. 1403, University of Miami, Rosenstiel School of Marine and Atmospheric Science. The support of Environmental Protection Agency Contract FW QA 18050 DIU, Water Quality Office, Division of Water Quality Research is gratefully acknowledged. 相似文献