Showing papers by "University of Kiel published in 1986"

Molecular stratigraphy: a new tool for climatic assessment

Abstract: Variations in sea-surface temperatures over the past 500,000 years are inferred from the relative abundance behaviour of two organic compounds, C37 alkenones over the upper 8 metres of a sediment core from the eastern equatorial Atlantic. This molecular record, ascribed to contributions from prymnesiophyte algae, correlates well with the variations in the δ18 signal for the calcareous skeletons of certain planktonic foraminifera, thus providing the first demonstration of a new stratigraphical technique, which may be especially valuable where methods based on carbonate δ18 fail.

Recent Research on Selective Exposure to Information

Abstract: Publisher Summary This chapter highlights the recent research on the selective exposure to information. The term “selective exposure” implies several assumptions concerning the decision-making process. It assumes that the seeking out of decision relevant information does not cease once a decision is made. This notion also implies that this post-decisional information seeking and evaluation is not impartial but, rather, is biased by certain factors activated during the decision-making process. This chapter discusses the fundamental theses of dissonance theory as it relates to selective exposure and gives a short overview of the early research. This chapter describes new research, including the experiments designed to specify those factors most important in influencing informational selectivity: the effects of choice and commitment on selective information seeking, selectivity and refutability of arguments, the amount of available information and its usefulness, the usefulness of decision reversibility, as well as the intensity of dissonance. This chapter reports the results on some additional variables-cost of information, the reliability of dissonant information, and the effects of personality.

Heavy metal species, mobility and availability in soils

Abstract: The ecological effects of heavy metals in soils are closely related to their content and species distribution in the solid and liquid phases of soils. Methods for the determination of metal species in both phases are described and critically evaluated. In connection with the possible binding mechanisms of heavy metals in soils the concept of specific and nonspecific adsorption is discussed. Recent results indicate that the adsorption of heavy metals on soil particles is not only restricted to the formation of surface complexes but can also take place in the structure of minerals. Diffusion processes of heavy metals into soil minerals are described for goethite. In order to assess metal mobility and availability in soils, the concentration of the species in the soil solution or in comparable aqueous equilibrium solutions of soil samples, and the transfer of metals from solid pools to the liquid phase, and vice versa, have to be assessed. Methods for the determination of the amount of plant-available heavy metals are described and the associated problems discussed.

Functional properties of spinal visceral afferents supplying abdominal and pelvic organs, with special emphasis on visceral nociception

Abstract: Publisher Summary This chapter discusses the functional and the morphological properties of the spinal visceral afferent neurons, supplying the abdominal and pelvic organs. These neurons are involved in the regulation of the visceral functions, in sensations and in various spinal and supraspinal reflexes. Special emphasis has been placed on the visceral nociception and pain. The spatial resolution of the sensations that can be elicited from the viscera is relatively vague and can be fully explained, by the segmental width of the afferent inflow from each viscus. Most spinal visceral afferent units have various common functional properties: they are silent or display a low rate of ongoing activity; their axons are unmyelinated or thinly myelinated (conduction velocity below 2 m/second and mostly below 20 m/second, respectively); their receptive fields consist of from 1-9 mechanosensitive sites located in the mesenteries on the serosal surface or on the walls of the organs; local pressure in their receptive fields elicits slowly adapting responses; they respond to distensions and contractions of the viscera and to stretching of their mechanosensitive endings; they respond to various chemical stimuli applied in their receptive fields.

Specification-oriented semantics for communicating processes

Abstract: A process P satisfies a specification S if every observation we can make of the behaviour of P is allowed by S. We use this idea of process correctness as a starting point for developing a specific form of denotational semantics for processes, called here specification — oriented semantics. This approach serves as a uniform framework for generating and relating a series of increasingly sophisticated denotational models for Communicating Processes. These models differ in the underlying structure of their observations which influences both the number of representable language operators and the induced notion of process correctness. Safety properties are treated by all models; the more sophisticated models also permit proofs of certain liveness properties. An important feature of the models is a special hiding operator which abstracts from internal process activity. This allows large processes to be composed hierarchically from networks of smaller ones in such a way that proofs of the whole are constructed from proofs of its components. We also show the consistency of our denotational models w.r.t. a simple operational semantics based on transitions which make internal process activity explicit.

Primary production and sedimentation during spring in the Antarctic Peninsula region

Abstract: Phytoplankton biomass and composition, primary productivity (in situ simulated and in vitro incubations) and sedimentation rates (measured with free-drifting sediment traps suspended at 100 m depth) were recorded in the Bransfield Strait area of the Antarctic Peninsula during November to December 1980. Three distinct and persistent zones were encountered: low biomass comprising flagellates and diatoms in the Drake Passage and Scotia Sea (zone I): high to moderate biomass of Phaeocystis and diatoms in the northern and central Bransfield Strait (zone II); and moderate biomass (Thalassiosira spp. in the process of forming resting spores) in the vertically homogeneous water on the northern Antarctic Peninsula shelf (zone III). Nutrient concentrations were high throughout; zooplankton grazing relative to phytoplankton biomass and production was heavy in zone I but negligible in the other 2 zones. Rates of primary production in zones I, II, and III averaged 230, 1660 and 830 mg C m−2 d−1, respectively. Assimilation numbers were low throughout (< 1 mg Chl a)−1 h−1) and growth physiology of the zonal phytoplankton assemblages was basically similar. Sedimentation rates recorded by 2 traps in zone II were low (97 and 138 mg C m−2 d−1) and higher (546 mg C m−2 d−1) in a third trap which collected mostly euphausiid faeces. Sedimentation was heaviest in zone III (450 to 1400 mg C m−2 d−1) where collections of the 3 traps deployed were dominated by intact diatom frustules (Thalassiosira spp.). Spore formation and heavy sedimentation of diatoms thus also occurs at the end of Antarctic blooms in spite of high ambient nutrients. As approximately two-thirds of the diatoms in traps were resting spores, we suggest that sinking of cells represents a seeding strategy which ensures regional persistence of neritic assemblages. Species-specific differences in seeding strategies may well be important in determining spatial and temporal patterns of Antarctic phytoplankton abundance. This aspect of phytoplankton biology is likely to have far-reaching implications, not previously considered, for the structure of Antarctic food webs.

The implication of a plastid-derived factor in the transcriptional control of nuclear genes encoding the light-harvesting chlorophyll a/b protein

Abstract: In carotenoid-deficient albina mutants of barley and in barley plants treated with the herbicide Norflurazon the light-dependent accumulation of the mRNA for the light-harvesting chlorophyll a/b protein (LHCP) is blocked. Thus, the elimination of a functional chloroplast, either as a result of mutation or as a result of herbicide treatment, can lead to the specific suppression of the expression of a nuclear gene encoding a plastid-localized protein. These results confirm and extend earlier observations on maize [Mayfield and Taylor (1984) Eur. J. Biochem. 144, 79–84]. The inhibition of mRNA accumulation appears to be specific for the LHCP; the mRNAs encoding the small subunit of ribulose-1,5-bisphosphate carboxylase and the NADPH:protochlorophyllide oxidoreductase are relatively unaffected. The failure of the albina mutants and of Norflurazon-treated plants to accumulate the LHCP mRNA is not exclusively caused by an instability of the transcript but rather by the inability of the plants to enhance the rate of transcription of the LHCP genes during illumination. Several chlorophyll-deficient xantha mutants of barley, which are blocked after protoporphyrin IX or Mg-protoporphyrin, and the chlorophyll-b-less mutant chlorina f2 accumulate the LHCP mRNA to almost normal levels during illumination. Thus, if any of the reactions leading to chlorophyll formation is involved in the control of LHCP mRNA accumulation it should be one between the formation of protochlorophyllide and the esterification of chlorophyllide a. While the nature of the regulatory factor(s) has not been identified our results suggest that, in addition to phytochrome (Pfr), plastid-dependent factors are required for a continuous light-dependent transcription of nuclear genes encoding the LHCP.

Distribution of biogenic silica and quartz in recent deep-sea sediments

Abstract: All available quartz and biogenic silica concentrations from deep-sea surface sediments were intercalibrated, plotted, and contoured on a calcium-carbonate-free basis. The maps show highest concentrations of biogenic silica (opal) along the west African coast, along equatorial divergences in all oceans, and at the Polar Front in the southern Indian Ocean. These are all areas where upwelling is strong and there is high biological productivity. Quartz in pelagic sediments deposited far from land is generally eolian in origin. Its distribution reflects dominant wind systems in the Pacific, but in much of the Atlantic and Indian oceans the distribution pattern is strongly modified by turbidite deposition and bottom current processes.

Functional characteristics of lumbar visceral afferent fibres from the urinary bladder and the urethra in the cat

Abstract: Neural activity of lumbar visceral afferents supplying the urinary bladder and urethra was analyzed systematically in the cat. The afferent fibres were isolated either from the white rami L3 and L4 in a preparation with closed peritoneal cavity, or from the lumbar splanchnic nerves in a preparation with open peritoneal cavity and investigated for various functional parameters. Seventy five single units and 9 multiunit bundles were analyzed. 1) About 50% of the afferent units had some ongoing activity (0.2 to 1 imp/s). Two thirds of the afferent axons were thin myelinated (conduction velocity 3–15 m/s), the rest were presumably unmyelinated (conduction velocity below 2 m/s). 2) The receptive fields of the afferent units consisted —with one exception — of single mechanosensitive sites on the surface of the bladder and urethra. Most receptive fields were situated on the dorsal side of the bladder. 3) Afferents with receptive fields on or in the bladder wall responded in a graded manner to passive distension and isovolumetric contraction at intravesical pressures ranging from about 10 to 70 mm Hg. The thresholds for exciting the afferent units ranged from less than 10 mm Hg to about 30 mm Hg intravesical pressure, most of them being less than 20 mm Hg. Generally, the discharge rate of the afferent units gave a reliable representation of the intravesical pressure to the lumbar spinal cord. 4) Urethral units exhibited either no responses to the graded distensions and contractions of the urinary bladder, or responded with low discharge rates at higher intravesical pressures. 5) The results do not support the notion that noxious events in the urinary bladder are encoded by “specific” nociceptive visceral afferents to the lumbar spinal cord but possibly by some other mechanism of encoding.

Operational Petri net semantics for CCSP

Abstract: We provide a Petri net semantics for a subset of CCSP, the union of Milner's CCS and Hoare's CSP. It assigns to each process term in the subset a labelled, one-safe place/transition net. As opposed to many other approaches to Petri net semantics, our definition is operational as it is based on Plotkin-style transition rules. These rules are inspired by work of Degano, DeNicola and Montanari, but differ in the way they model the interplay of the central concepts in CCSP: concurrency, nondeterminism and recursion. To discuss these differences, we propose criteria for a good Petri net semantics for CCSP.

Localization of NADPH‐protochlorophyllide oxidoreductase in dark‐grown wheat (Triticum aestivum) by immuno‐electron microscopy before and after transformation of the prolamellar bodies

Abstract: The localization of NADPH-protochlorophyllide oxidoreductase (PChlide reductase, EC 1.6.99.–) in dark-grown and in irradiated dark-grown leaves of wheat (Triticum aestivum L. cv. Walde) was investigated by subjecting thin sections of Lowicryl K4M-embedded leaf pieces to a monospecific antiserum raised against PChlide reductase followed by protein A-gold. A well-preserved antigenicity of the tissue was achieved by polymerizing the resin under UV-light at low temperature. In dark-grown leaves PChlide reductase was found in prolamellar bodies only. In leaves irradiated for 30 min with white light PChlide reductase was found not only in the transformed prolamellar bodies but also to a large extent in connection with the prothylakoids. The localization of PChlide reductase is discussed in relation to fluorescence emission spectra of the dark-grown and greening leaves. We conclude that the light-dependent transformation of protochlorophyllide to chlorophyllide initiates a translocation of PChlide reductase from the prolamellar bodies to the prothylakoids.

Chemical composition of the peptidoglycan-free cell envelopes of budding bacteria of the Pirella/Planctomyces group

Abstract: Cell envelopes were prepared from freeze-dried cells of 8 strains of budding bacteria belonging to the Pirella/Planctomyces group. Treatment with 10% sodium dodecylsulfate (SDS) (30 min, 100°C) allowed the isolation of stable cell sacculi which still maintained the original cell shape. The chemical analysis showed, as the main component, protein which was unusually rich in proline and cystine. Except for Planctomyces maris IFAM 1317 (where this protein comprised 62.6% of the total envelope dry weight) the corresponding values for the other strains varied from 75 to 82%. Amino sugars and neutral sugars were present only in small amounts and uronic acids were not found. The ash content varied from 5 to 10% of the dry weight, except for IFAM 1317 which had 19% ash. The high content of cystine indicated a high degree of crosslinking of the cell envelopes through disulfide bonds. Our data show that bacteria of the Pirella/Planctomyces group possess a similar cell wall composition.

Three morphologically distinct types of interface develop between adult host and fetal brain transplants: implications for scar formation in the adult central nervous system.

Abstract: The development of the host/graft interface of cerebellar and cerebral transplants was studied 1-60 days after operation. Grafts from fetal Wistar rats were transplanted to a cavity over the superior colliculus of adult rats by removing parts of the overlying cortex and hippocampus according to the Bjorklund/Stenevi technique. In sham-operated control rats, in which a cavity was made in the brain but no graft was implanted, the parenchyma bordering the entire cavity developed a complete glial-meningeal scar within 2 weeks after operation consisting of multilayered glial processes, a basal lamina, and fibroblasts (meningeal cells). A similar interface also developed between graft and host in the most superficial parts of the transplantation cavity. In the basal parts of the transplantation cavity, the host/graft interface consisted either of an incomplete sheet of astrocyte processes aligned in parallel to each other but without a covering basal lamina or of completely fused neuropil without any morphological signs of separation between host and transplant. It is concluded that these three zones of host/graft interface are established by differential interaction between the growing transplant and the host cicatrix. At the basal host/graft parenchymatous interface the fetal transplant interferes with the normal adult cicatrization process of the host, possibly by either releasing inhibitory factors or by preventing contact between the astroglia of the host and fibroblasts (meningeal cells). In white matter regions of the transplantation cavity, voluminous cysts developed, both in sham-operated controls and in graft recipients, which were invaded by transplanted neurons.

A New Synthesis Algorithm for the MIMOLA Software System

Abstract: The MIMOLA software system is a system for the design of digital processors The system includes subsystems for retargetable microcode generation, automatic generation of self-test programs and a synthesis subsystem This paper describes the synthesis part of the system, which accepts a PASCAL-like, high-level program as specification and produces a register transfer structure Because of the complexity of this design process, a set of sub-problems is identified and algorithms for their solution are indicated These algorithms include a flexible statement decomposition, statement scheduling, register assignment, module selection and optimizations of interconnections and instruction word length

Thermochemistry of MgAl2O4‐Al8/3O4 Defect Spinels

Abstract: Solution calorimetry of MgAl2O4-Al8/3O4 solid solutions was performed in a molten 2PbO · B2O3 solvent at 975 K. The results indicate small negative heats of mixing, relative to spinel standard states for both end-members. These data were combined with information on the energetics of the α-γ transition in Al2O3 and on the MgAl2O4-Al8/3O4 (MgO-Al2O3) subsolidus phase relations to estimate the partial molar entropy of mixing of γ-Al8/3O4 in the solid solution. This entropy is much less positive than that calculated from several models for the configurational entropy of mixing of magnesium, aluminum, and vacancies on octahedral and/or tetrahedral sites. The data suggest a good deal of local order to be present in the solid solutions, consistent with negative enthalpies of mixing and entropies of mixing far less than ideal configurational values.

Effects of NH+4‐N and NO+3‐N on growth and metabolism of Sphagnum magellanicum

Abstract: Photosynthetic CO2-fixation, chlorophyll content, growth rate and nitrate reductase activity were used to examine the influence of NH+4-N and NO−3-N on Sphagnum magellanicum cultivated under defined conditions in phytotrons. NO−3-concentrations up to 322 μM were found to be favourable. Increased NH+4 concentrations, however, resulted in growth inhibition and decreased chlorophyll content at concentrations ≧ 255 μM; e.g. 600 μM NH+4 caused a 20% reduction of nitrate reductase activity and net photosynthesis. For raised bog Sphagna an improved standard nutrient solution is proposed with the following ion concentrations (μM): 55 Na+; 17 K+; 95 NH+4; 22 Ca2+; 22 Mg2+; 2 Fe3+; 20 Cl−; 100 NO−3; 57 SO2-4; 7.4 H2PO−4; trace elements: A-Z solution (Hoagland) 50 μl 1000 ml−1; pH 5.8.

Phytoplankton growth and krill grazing during spring in the Bransfield Strait, Antarctica — Implications from sediment trap collections

Abstract: Phytoplankton primary production, biomass, species composition and sedimentation of organic matter (using a moored and a free drifting sediment trap) were measured in eastern Bransfield Strait during spring 1983. Biomass and primary production increased from low levels in late November (1 mgChla m-3 and 400 mgC m-2 d-1) to bloom levels by the end of December (5 mgChla m-3 and 1000 mgC m-2 d-1). The moored trap was deployed at 323 m depth for 22.5 days, and collected 2968 mgC and 67.6 mg chlorophyll a and derivatives per m2 (132 and 3.0 mg m-2 d-1), of which 90% was in the form of krill faeces. These figures are regarded as egestion of krill, and using ingestion: egestion ratios from the literature, grazing loss of phytoplankton by krill was estimated at 45% of the primary production during a period of 3 weeks. Large-scale surveys of phytoplankton standing stock indicate that the build-up of blooms during spring is apparently not controlled by krill grazing. It is therefore suggested that the intense grazing that must have occurred over the trap during the period of deployment was only of local importance.

Germ cell tumours of childhood. Report of 170 cases including 59 pure and partial yolk-sac tumours.

Abstract: 170 germ cell tumours of childhood and adolescence were studied by light microscopy and immunohistochemistry. The male-to-female ratio was 1:1.3. 52 (30.6%) tumours were benign (mature teratoma), 30 (17.6%) potentially malignant (immature teratoma), and 88 (51.8%) unequivocally malignant. The main locations were ovary, testis and sacrococcygeal region. 92 tumours were located in a gonad, 78 tumours in extragonadal sites (ratio: 1.2:1). Of the frankly malignant tumours 40 were yolk-sac tumours (YST) and an additional 19 tumours of more than one histological type contained a YST component. Therefore, 67% of the malignant tumours had a YST component. Children with immature teratoma and pure YST showed the lowest median age (5 and 24 months, respectively), while children with germinomas of various locations had the highest median age (153 months). A festoon pattern was the predominant histological feature in all YST and in the YST component of mixed germ cell tumours. Hyaline globules were found in 33/37 YST and in 16/17 YST components. Immunohistochemically, alpha 1-fetoprotein (AFP) was demonstrated in 18/22 YST and in 6/7 YST components of mixed germ cell tumours. Hyaline globules were mostly AFP-negative (only 5 cases with AFP-positive globules in addition to many AFP-negative globules). In 3 cases beta-HCG-positive giant cells were seen. In most YST prekeratin intermediate filaments could be demonstrated in the epithelial cells. Follow-up data, available from 51 cases of YST and tumours with YST components showed disease-free survival in 37 cases (72.5%). 10 patients (19.6%) died of disease, and 4 patients (7.8%) are living with disease. The comparably high rate of survivors reflects the effectiveness of modern therapy, particularly polychemotherapy, in addition to surgery.

A monoclonal antibody that detects myoepithelial cells in exocrine glands, basal cells in other epithelia and basal and suprabasal cells in certain hyperplastic tissues.

Abstract: Myoepithelial and luminal cells of human exocrine glands can be positively identified with two different monoclonal antibodies. Myoepithelial cells including those of the salivary gland, mammary gland and sweat gland are positively identified by an antibody CKB1. This antibody does not stain luminal cells, but stains the basal cell layer of certain human stratified epithelia and a few basal cells in simple epithelia. Thus myoepithelial cells and basal cells have certain common features. Luminal cells can be positively stained with the CK5 monoclonal keratin antibody specific for keratin polypeptide 18; this antibody does not stain myoepithelial cells. Of interest is that CKB1 also appears to stain basal and suprabasal cells in certain hyperplastic conditions.