Search

High-spin states in Ba-124 were investigated in two experiments using the Ni-64(Ni-64, 4n)Ba-124 reaction at three different beam energies. In-beam gamma-ray coincidences were measured with the Euroball and Gammasphere detector arrays. In the experiment with Euroball, the CsI detector array Diamant was employed to discriminate against charged-particle channels. Six new rotational bands were observed in Ba-124, and previously known bands were extended to higher spins. One of the bands shows a transition from collective to noncollective behavior at high spins. Configuration assignments are suggested on the basis of comparison with cranked shell model and cranked Nilsson-Strutinsky calculations.

ECOTOX is als module ontworpen voor BONANZA, een decision-support systeem (DSS) voor de risicobeoordeling van nutriënten en zware metalen voor de flora en fauna in natuurterreinen. In de huidige vorm richt de module zich specifiek op de berekening van de ecologische effecten van zware metalen op het ecosysteem en op de terrestrische fauna met gebruik van locatiespecifieke databases en bodemchemische modellen. De resultaten worden gevisualiseerd in kaarten, grafieken of opzoektabellen. Relevante modelsoorten zijn receptor van bodemverontreiniging en kunnen zowel bepaalde natuurdoelsoorten van de Ecologische Hoofdstructuur zijn als beschermde soorten en sleutelsoorten. De risicoberekeningen geschieden langs een drietal parallelle sporen, te weten: (i) een statistische risicobenadering voor een generieke samenstelling van terrestrische organismen; (ii) een deterministische modellering van effecten op dieren op basis van soortspecifieke voedselkeuze, en (iii) de modellering van de lange-termijn gevolgen voor de grootte van de populatie. De module ondersteunt de geïntegreerde beoordeling van actuele en potentiële ecologische risico’s in verontreinigde natuurgebieden en draagt bij aan technisch-wetenschappelijk en economisch verant¬woorde besluitvorming ten aanzien van de ontwikkeling en het beheer van natuur in verontreinigde gebieden

Dit rapport beschrijft een onderzoek naar de populatie-ecologie van regenwormen (Oligochaeta, Lumbricidae) in de Afferdensche en Deestsche Waarden (ADW), een uiterwaarde van de rivier de Waal. Ondanks het feit dat de bodem in dit gebied is verontreinigd en elk jaar overstromingen plaatsvinden komen regenwormen er in een grote soortsdiversiteit en in grote aantalsdichtheden voor. Afhankelijk van de bodemgesteldheid omvat de totale gemiddelde populatie een biomassa van 1500 kg per hectare. De uiterwaarden vormen hiermee een belangrijk voedselzoekgebied voor vermivore (wormenetende) faunasoorten en dragen als zodanig bij aan de totale biodiversiteit van de natuur in Nederland. Om de ecologische betekenis van multipele stress in beeld te brengen is onderzoek verricht naar de invloed van potentieel sturende omgevingsfactoren, waaronder hoogteligging, textuur en verontreiniging van de bodem, nutriëntengehalten en bodemvocht. Uit (multivariate) statistische analyse bleek dat de hydrodynamiek van het gebied en het bodemvochtgehalte belangrijke sturende variabelen vormden voor de soortsdiversiteit en populatiedichtheden, terwijl de aanwezige metaalverontreiniging in dit opzicht van mindere betekenis was. Vanuit het oogpunt van praktische toepasbaarheid leveren de resultaten belangrijke aanknopingspunten op voor het bodem- en natuurbeheer van de uiterwaarden in Nederland.

The occurrence of the earthworm Allolobophora cupulifera in the Netherlands (Oligochaeta: Lumbricidae) First records are described of the occurrence of the earthworm Allolobophora cupulifera (Tétry, 1937) in the Netherlands. One population of this rare species was found in a grassland site on peaty clay soil in the Kortenbroek polder along the river Lek in the south-western part of the Netherlands. Another population was found in a grassland site on clay loam soil in the Afferdensche en Deestsche Waarden, a flood plain area (river foreland) of the river Waal in the centre of the Netherlands. The finding in moist habitats situated near water agrees with an ecological classification of A. cupulifera as a hygrophilous and relatively acid-tolerant riparian species. The species occurs at relatively low numbers in small localized sites. According to the presently reported findings, together with the available literature, it may be suggested that the distribution of the species incorporates the whole Rhine estuary. Its range extends to the island of Fynn in Denmark in the north and to Marseille (France) in the south. The eastern border is formed by the region of Bonn and the valley of the river Mosel. There are no reports from Great Britain. An anomalous specimen of the species is described.

De monitoring betreft de afbraak van PAK, minerale olie; en het gedrag van zware metalen. De species zijn afkomstig van de Geulhaven (Rotterdam), de havens van Wemeldinge en Zierikzee, de Petroleumhaven (Amsterdam)

De Broekpolder bij Vlaardingen is in de jaren zestig en zeventig opgespoten met zwaar verontreinigd Rotterdams havenslib. Vooral zware metalen en cyclodieeninsecticiden (drins) komen in hoge concentraties voor. Dit kan een belemmering vormen voor plannen om een gedeelte van de Broekpolder te bestemmen voor natuur- en landschapsontwikkeling door het uitzetten van grote grazers, zoals Schotse Hooglanders. In dit rapport wordt nagegaan of extensieve begrazing in de Broekpolder tot gezondheidsrisico's voor de dieren kan leiden. Bij de risicoberekeningen wordt de inname van gronddeeltjes, vegetatie en oppervlaktewater en de daarin aanwezige verontreiniging in beschouwing genomen. Geconcludeerd wordt dat extensieve begrazing in de door de gemeente Vlaardingen daarvoor aangewezen delen van de Broekpolder wel toelaatbaar is, mits uitgegaan wordt van een gespreid begrazingsbeheer.

Het relatieve effect van verkeersmortaliteit en blootstelling aan zware metalen (effect op de voortplanting) op de veranderingen van regionale populatie-aantallen van dassen. Met de verkeersdruk kon geen statistisch verband worden aangetoond; wat betreft zware metalen zijn vooral populaties in de nabijheid van de grote rivieren kwetsbaar

The highest-spin discrete states (I ∼ 60ℏ and Ex ∼ 30MeV) in normal deformed nuclei have been observed in the rare-earth isotope 156Dy using the GAMMASPHERE spectrometer. The quadrupole moments for a variety of configurations, including the 9/2+[404] (g9/2) proton, 1/2+[660] (i13/2) and 1/2-[541] (f7/2, h9/2) neutron orbitals, were measured in a wide range of ∼ 130 nuclei.

Om het risico op verspreiding en het ecotoxicologische risico van de chroom- en arseenverontreiniging van de vloeivelden `Zandleij' in Tilburg te bepalen is een literatuuronderzoek uitgevoerd naar de chemie en ecotoxicologie van beide elementen. De oxidatietoestand van chroom en arseen is van groot belang voor hun mobiliteit en toxiciteit. De oxidatietoestand hangt af van bodemeigenschappen zoals pH en organisch stofgehalte. In de delen met hoge concentraties Cr kunnen toxische effecten verwacht worden voor de bodemfauna. Dit is bevestigd met een verkennend experiment met regenwormen. Het effect op de vegetatie is waarschijnlijk gering. De kans op verspreiding is onder de huidige omstandigheden klein.

Om het ecologisch risico vast te stellen van een verontreiniging met chroom, arseen en zware metalen in de bodem van de voormalige vloeivelden is een gecombineerd ecotoxicologisch en bodemchemisch onderzoek uitgevoerd. Uit het ecotoxicologisch onderzoek bleek geen aantoonbaar negatief effect van de verontreiniging op regenwormen en gras. Uit het bodemchemisch onderzoek blijkt dat de actuele beschikbaarheid van de verontreiniging met chroom en arseen gering is. De actuele beschikbaarheid van de metalen Zn, Cd en Cu bleek echter in de sterk verontreinigde delen relatief hoog te zijn. Onder de huidige omstandigheden worden geen duidelijk negatieve effecten verwacht. Bij een toekomstig gebruik van het gebied als bos zal zonder tegenmaatregelen de bodem verzuren met als gevolg een stijging van de beschikbaarheid van Cr, Zn, Cu en Zn.

The present study of contact chemoreception in Pieris brassicae L. is divided into three major parts, viz. 1. behavioural analyses, 2. the identification and description of sense organs and 3. investigations concerning the sensory physiology. In a separate section some of the results were put into a coherent discussion.In the behavioural studies the food selection behaviour was investigated as well as the behavioural responses to single or combined chemical stimuli (Chapter 3 and 4). It was found that the preference order for certain food plants can be strongly influenced by previous experience. Herein the time of experience, the species of food plant concerned and the choice-situation itself are playing an important rôle. The various experiments indicated that modifications in preferences were related to learning processes rather than to changes in the physiology of the relevant sense organs. In extirpation experiments it was found that the very subtle discriminative capacity and the possibility to induce preference modification remain unaffected by bilateral maxillectomy.With respect to the above phenomenon the studies of the behaviour to chemical stimuli were performed with larvae reared on a meridic diet. The food intake behaviour of the larvae on this diet was used for deriving several response parameters, among which were frequency and time intervals of mouth part movement and measurement of quantities of food ingested. Only sucrose and D-glucose appeared to be able to induce an actual food ingestion. Fructose and other mono-, di- or trisaccharides were completely ineffective. From the stimulus- response relationships investigated it was deduced that sucrose is a much more effective stimulus than glucose. The relationship between stimulus intensity and behavioural response was also studied in relation to starvation of the experimental animals.Other types of chemical stimuli, such as mustard oil glucosides, amino acids, salts and ascorbic acid are unable to induce food intake but show a positive interaction when mixed sub-optimally stimulating concentrations of sucrose. It was found that the stimulus-response relationships established for mustard oil glucosides differed in an essential way from those established for the remaining compounds. Several indications were found that the maxillary palpi exert an endogenous inhibiting effect on the onset of food intake.The larvae demonstrated a high sensitivity to alkaloids and steroids which inhibited food intake. For these inhibitors the relationships between stimulus intensity and behavioural response were quantitatively analysed in relation to different types of feeding substrates. In ablation experiments it was found that bilateral maxillectomy or galeaectomy resulted in a loss of responsiveness to mustard oil glucosides. However, this was not the case after bilateral palpectomy. The sensitivity to sucrose, glucose, alkaloids or steroids was not affected by bilateral maxillectomy.Chapter 5 concerns the identification and description of the structure of a number of sense organs which play an important rôle in food discrimination. The structure of the maxillary sensilla styloconica was electron-microscopically investigated. The medial and the lateral sensilla styloconica contain five bipolar neurons each. Four neurons possess distal processes which stand in contact with the external environment by a pore opening of about 190 mμdiameter. The fifth cell, which is a mechanoreceptor, has a dendrite which terminates without modification at the base of the flexible papilla at the end of the sense organ. In all five dendrites the transitional region from inner and outer segment is characterized by the presence of a modified ciliary connecting structure with two basal bodies. The axonema contains peripheral doublets according to a '9 + 0' configuration. The base of the scolopale, the proximal segments of the dendrites, the perikarya and a part of the axons are enveloped by the trichogen cell. The distal parts of the trichogen cell is surrounded by two tormogen cells.On the basis of the results of several behavioural experiments investigation was made of the localisation of sense organs in the buccal cavity. In the epipharynx three types of sense organs were found, viz. setae, sensilla campaniformia and papilla-like organs. Each seta and sensillum campaniformium is innervated by one sense cell. Each of the papilla-like organs contains three bipolar neurons of which the dendrites terminate in a small papilla of approximately 0.5 mμdiameter and 0.5 0.7μlong. Of both sensilla campaniformia and papilla-like organs one pair is present in the epipharynx.Other sense organs which possibly could contribute to the highly developed discriminative capacity were found in the incisor cusps of the mandibles. Herein a number of pore canals are present which each are associated with one pair of bipolar sense cells. Electronmicroscopic investigation showed that the dendrites run to the distal termination of the pore canals. Several ultra-structural features of the pore canal organs suggested a resemblance to the structure of scolopidia.In the investigations on the sensory physiology (Chapter 6) the epipharyngeal papilla-like organs were identified as chemoreceptive sense organs. Of the three bipolar neurons of each sensillum two were electrophysiologically characterized as a salt sensitive cell and a sugar sensitive cell. The third receptor responded specifically to stimulation with solutions of some alkaloids and steroids. The papilla-like organs do not contain any receptors sensitive to mustard oil glucosides. On the basis of responses to stimulation with different stimulus qualities and intensities it was concluded that the salt sensitive cells in the medial sensilla styloconica and the papilla-like organs are functionally almost identical. This was also true for the receptors sensitive to stimulation with alkaloids and steroids which were present in the same sense organs. To a certain extent the sugar sensitive cells in the papilla-like organs appeared to correspond functionally to the receptors in the lateral sensilla styloconica. Although both types of receptors were specifically sensitive to sucrose and glucose the stimulus-response relationships were quantitatively somewhat different. In both cases, however, it appeared that sucrose provided a more effective stimulus than glucose. In view of theoretical considerations it was assumed that the cell membrane of the sugar sensitive receptors in the lateral sensilla styloconica and the papilla-like organs possess one type of receptor site with two subunits. Each receptor site would be occupied by one molecule of sucrose or two molecules of glucose. In the medial sensilla styloconica a sugar receptor was identified having a broader sensitivity spectrum, which included sucrose, glucose, fucose and fructose as effective stimuli.The presence of sodium or calcium chloride in the stimulating solution could strongly influence the responsiveness of the sugar sensitive receptors. In contrast to sodium chloride the effect of calcium chloride was exclusively inhibitory. A corresponding effect of calcium chloride was observed with regard to the responsiveness of the receptors sensitive to alkaloids and steroids.Concerning some receptor cells in the medial sensilla styloconica and the papilla- like organs it appeared that an absolute receptor specificity could not be assumed under all conditions of stimulation.In Chapter 7 the possible causal relations between quantitative electrophysiological events in chemoreceptor cells and various measurable behavioural responses to chemical stimuli are dealt with. Several aspects and problems related to such a study were discussed briefly. In situations in which chemical stimuli were presented individually a reasonable qualitative and quantitative correspondance was determined for distinct behavioural responses and the electrical activity of the relevant chemoreceptors. This, however, was valid only for the behavioural response to sucrose and glucose and the response characteristics of the sugar receptors in lateral sensilla styloconica and the papillalike organs. At lower concentrations a deviation from a direct proportionality between both stimulus-response relationships was found, which was ascribed to the endogenous inhibiting influence exerted by the palpi. A good correspondance was apparent when the quantitative stimulus-response relationships of maxillectomized larvae were compared with the electrophysiological response characteristics of the sugar receptor in the papilla-like organs. The fundamental significance of the sugar sensitive receptors in inducing food intake was, among others, also deduced from the fact that a suppression of the responsiveness of the sugar receptors by calcium chloride resulted in a proportional reduction in food intake. On the basis of the results of different experiments the hypothesis was advanced that the actual ingestion of food into the foregut is controlled by the sense organs located in the epipharynx, whereas biting responses are under control of the sense organs in the maxillae. Herein the mustard oil glucosides are belonging to stimuli which exclusively elicit biting responses.The functional significance of the various chemoreceptors located in the maxillae can show large relative differences. Thus the sugar receptor which was electrophysiologically identified in the medial sensilla styloconica was inconsequential in influencing biting responses. Some receptors, such as the salt sensitive receptors, may evoke a stimulation as well as an inhibition of behavioural responses, depending on the stimulus intensity.In situations in which, combinations of different stimulus qualities were presented the influence of the integrating mechanisms in the central nervous system on the quantitative behavioural responses was studied. Apart from the existence of positive interactions demonstrated for certain stimulus qualities, it was found that negative interactions were apparent in behavioural responses to specific inhibiting stimuli relative to the stimulating value of the feeding substrate. This means that the larvae reacted more sharply to small differences in stimulus intensities of specific inhibitors in the presence of a highly stimulating substrate than when the substrate possessed a lower stimulating value. An electrical activity in the alkaloid sensitive receptors approaching saturation level was related to the occurrence of an absolute inhibition of food intake.