Showing papers by "University of Kiel published in 1992"

Recent developments in modeling preferences: Uncertainty and ambiguity

Abstract: In subjective expected utility (SEU), the decision weights people attach to events are their beliefs about the likelihood of events. Much empirical evidence, inspired by Ellsberg (1961) and others, shows that people prefer to bet on events they know more about, even when their beliefs are held constant. (They are averse to ambiguity, or uncertainty about probability.) We review evidence, recent theoretical explanations, and applications of research on ambiguity and SEU.

Cytokine RANTES released by thrombin-stimulated platelets is a potent attractant for human eosinophils.

Abstract: Thrombin stimulation of human platelets results in the release of a preformed proteinaceous human eosinophil (Eo)-chemotactic activity. By the use of different high-performance liquid chromatography techniques, two Eo-chemotactic polypeptides (EoCPs), tentatively termed EoCP-1 and EoCP-2, were purified to homogeneity. Upon SDS-PAGE analysis, these chemotaxins showed molecular masses near 8 kD. NH2-terminal amino acid sequence analysis revealed identical sequences for both EoCP-1 and EoCP-2, which are also identical to that of RANTES, a cytokine that structurally belongs to the interleukin 8 superfamily of leukocyte selective attractants, and that is known to be a "memory-type" T lymphocyte-selective attractant. In the major Eo chemotaxin, EoCP-1, the residues 4 and 5, which in EoCP-2 were found to be serine residues, could not be identified. Electrospray mass spectrometry (ESP-MS) of EoCPs revealed for EoCP-2 a molecular mass of 7,862.8 +/- 1.1 daltons, which is 15.8 mass units higher than the calculated value of RANTES, indicating that EoCP-2 is identical to the full-length cytokine, and oxygenation, probably at methionine residue number 64, has taken place. Upon ESP-MS, EoCP-1 showed an average molecular mass of 8,355 +/- 10 daltons, suggesting O-glycosylation at these serine residues. Both natural forms of RANTES showed strong Eo-chemotactic activity (ED50 = 2 nM) with optimal chemotactic migration at concentrations near 10 nM, however, there were no significant migratory responses with human neutrophils. Chemotactic activity of RANTES for human Eos could be confirmed using recombinant material, which has been found to be as active as the natural forms. Since RANTES gene expression has been detected in activated T lymphocytes, and recombinant RANTES was shown to be a "memory" T lymphocyte-selective attractant, it is now tempting to speculate about an important role of RANTES in clinical situations such as allergene-induced late-phase skin reactions in atopic subjects or asthma, where in affected tissues both memory T cells and Eos are characteristic.

Ecology of sea ice biota 2. Global significance.

Abstract: The sea ice does not only determine the ecology of ice biota, but it also influences the pelagic systems under the ice cover and at ice edges. In this paper, new estimates of Arctic and Antarctic production of biogenic carbon are derived, and differences as well as similarities between the two oceans are examined. In ice-covered seas, high algal concentrations (blooms) occur in association with several types of conditions. Blooms often lead to high sedimentation of intact cells and faecal pellets. In addition to ice-related blooms, there is progressive accumulation of organic matter in Arctic multi-year ice, whose fate may potentially be similar to that of blooms. A fraction of the carbon fixed by microalgae that grow in sea ice or in relation to it is exported out of the production zone. This includes particulate material sinking out of the euphotic zone, and also material passed on to the food web. Pathways through which ice algal production does reach various components of the pelagic and benthic food webs, and through them such top predators as marine mammals and birds, are discussed. Concerning global climate change and biogeochemical fluxes of carbon, not all export pathways from the euphotic zone result in the sequestration of carbon for periods of hundreds of years or more. This is because various processes, that take place in both the ice and the water column, contribute to mineralize organic carbon into CO2 before it becomes sequestered. Processes that favour the production and accumulation of biogenic carbon as well as its export to deep waters and sequestration are discussed, together with those that influence mineralization in the upper ice-covered ocean.

Sea surface wind stress and drag coefficients: The hexos results

Abstract: Turbulent fluxes have been measured in the atmospheric surface layer from a boom extending upwind from the Dutch offshore research platform Meetpost Noordwijk (MPN) during HEXMAX (Humidity Exchange over the Sea Main Experiment) in October–November, 1986. We started out to study eddy flux of water vapour, but discrepancies among simultaneous measurements made with three different anemometers led us to develop methods to correct eddy correlation measurements of wind stress for flow distortion by nearby objects. We then found excellent agreement among the corrected wind stress data sets from the three anemometers on the MPN boom and with eddy correlation measurements from a mast on a tripod. Inertial-dissipation techniques gave reliable estimates of wind stress from turbulence spectra, both at MPN and at a nearby ship. The data cover a range of wave ages and the results yield new insights into the variation of sea surface wind stress with sea state; two alternative formulas are given for the nondimensional surface roughness as a function of wave age.

The Production of New and Similar Vowels by Adult German Learners of English

Abstract: The study reported in this paper examined the effect of second language (L2) experience on the production of L2 vowels for which acoustic counterparts are either present or absent in the first language (L1). The hypothesis being tested was that amount of L2 experience would not affect L1 German speakers' production of the “similar” English vowels /i, l, ∈/, whereas English language experience would enable L1 Germans to produce an English-like /ae/, which has no counterpart in German. The predictions were tested in two experiments that compared the production of English /i, l, ∈, ae/ by two groups of L1 German speakers differing in English language experience and an L1 English control group. An acoustic experiment compared the three groups for spectral and temporal characteristics of the English vowels produced in /bVt/ words. The same tokens were assessed for intelligibility in a labeling experiment. The results of both experiments were largely consistent with the hypothesis. The experienced L2 speakers did not produce the similar English vowels /i, l, ∈/ more intelligibly than the inexperienced L2 speakers, not did experience have a positive effect on approximating the English acoustic norms for these similar vowels. The intelligibility results for the new vowel /ae/ did not clearly support the model. However, the acoustic comparisons showed that the experienced but not the inexperienced L2 speakers produced the new vowel /ae/ in much the same way as the native English speakers.

Ecology of sea ice biota - 1. Habitat, terminology, and methodology

Abstract: Polar regions are covered by extensive sea ice that is inhabited by a variety of plants and animals. The environments where the organisms live vary depending on the structure and age of the ice. Many terms have been used to describe the habitats and the organisms. We here characterize the habitats and communities and suggest some standard terms for them. We also suggest routine sampling methods and reporting units for measurements of biological and chemical variables. © 1992 Springer-Verlag GmbH & Co. KG.

The parasitic behaviour of second-stage juveniles of Meloidogyne incognita in roots of Arabidopsis thaliana

Abstract: The parasitic behaviour of second-stage juveniles (J2) of Meloidogyne incognita in roots of Arabidopsis thaliana was recorded at 25 ± 1 °C with the aid of video-enhanced contrast light microscopy and time lapse techniques. The J2 invaded the root primarily in the region of elongation, close to the meristematic zone. Invasion was achieved, in most cases, by destroying epidermal and subepidermal cells, while intercellular invasion between epidermal cells was less frequent. Inside the root the J2 oriented themselves always in the direction of the root-tip and migrated towards it between cortical and meristematic cells without causing any damage. Occasional attempts at intracellular migration through cortical cells were observed but these failed due to insurmountable barriers. When the J2 reached the apex of the root, they turned round and migrated backwards between the cells towards the differentiating vascular cylinder. Within the differentiated cylinder migration eventually stopped and giant-cell induction was initiated. After a period of induction, the J2 became surrounded by young multinucleate giant-cells within about 24 h. A characteristic behavioural pattern, composed of continuous head and stylet movements, interspersed by periods of stylet-tip protrusion and metacorpal bulb pumping, was maintained throughout all phases of parasitism, also when the J2 fed from the young giant-cells.

Calcitonin in phantom limb pain: a double-blind study.

Abstract: Salmon calcitonin (s-CT) has been shown to be a valuable analgesic in phantom limb pain (PLP) in several case reports. To evaluate these findings a double-blind crossover comparison of s-CT treatment versus placebo was initiated. Twenty-one out of 161 patients who had undergone major amputations and developed severe PLP 0-7 days after surgery were included in the study. For each patient a matched pair of infusions was prepared containing either 200 IU of s-CT or placebo. Group I (n = 11) was first given s-CT and group II (n = 10) placebo. When PLP reached a level of more than 3 on a numeric analogue scale (NAS) the first infusion was administered. The second infusion (crossover) or more infusions were given when the pain level again exceeded more than 3 on NAS. Using s-CT infusion, PLP was eased from a median of 7 to 4 on NAS in both groups (P less than 0.001), regardless of whether s-CT or placebo was given first. Placebo, however, did not change pain scores (median 7 on NAS, P greater than 0.1). In the s-CT group, but not in the placebo group, 4 individuals remained pain free without a second infusion. Any further treatment was performed with s-CT. One week after the first PLP treatment 19 patients (90%) had pain relief of more than 50%, 16 (76%) were completely pain free, and 15 (71%) never experienced PLP again. One year later 8 out of the 13 surviving patients (62%) still had more than 75% PLP relief. After 2 years PLP exceeded 3 on NAS in 5 individuals (42%), and the remaining 12 patients presented the same PLP as after 1 year. In conclusion, s-CT is a valuable treatment for PLP in the early postoperative period.

The identification of leaf thionin as one of the main jasmonate-induced proteins of barley (Hordeum vulgare).

Abstract: Jasmonic acid (JA) and its methyl ester (JA-Me) are able to introduce the accumulation of several specific polypeptides in cut leaf segments of barley. Two of the most prominent JA-induced proteins of M r 15 000 and 23 000 have been characterized by isolating and sequencing complete cDNA sequences. While the sequence of the M r 23 000 polypeptide shows no similarity to published sequences, the sequence of the M r 15 000 polypeptide corresponds to the higher-molecular-weight precursor of a leaf thionin previously characterized. Transcripts for the M r 23 000 and M r 15 000 polypeptides accumulate in leaf segments shortly after the beginning of JA treatment. JA and JA-Me induce the appearance of the two proteins not only in leaf segments but also in intact barley seedlings. However, in seedlings the accumulation of JA-induced proteins occurs much more slowly and requires high concentrations of volatile JA-Me. Thus, in barley it seems unlikely that volatile JA-Me is involved in the interaction between different members of this species, as has been proposed recently for tomato seedlings.

Occurrence of sialic acids in Drosophila melanogaster.

Abstract: Sialylated oligosaccharides, which are cell type-specific and developmentally regulated, have been implicated in a variety of complex biological events. Their broad functional importance is reflected by their presence in a wide variety of phyla extending from Echinodermata through higher vertebrates. Here, sialic acids are detected throughout development in an insect, Drosophila. Homopolymers of alpha 2,8-linked sialic acid, polysialic acid, are developmentally regulated and only expressed during early Drosophila development.

Molecular record of secular sea surface temperature changes on 100-year timescales for glacial terminations I, II and IV

Abstract: HIGH-RESOLUTION palaeoclimate records based on oxygen isotope data have provided important insights into climate variability and rates of natural climate change on about a thousand-year timescale1–3. Little is known4, however, about the variation of climate and of palaeoceanographic conditions throughout the Quaternary on timescales of less than 1,000 years (at frequencies far greater than those of the Milankovitch orbital cycles). Here we show that such high time resolution is possible from molecular stratigraphic studies based on 'biomarker' organic molecules (alkenones). We have sampled alkenone stratigraphic records at 70- to 200-yr intervals across glacial terminations I, II and IV in sediment cores from OOP site 658, off northwest Africa5. Sea surface temperatures (SSTs) derived from the alkenone (Uk37) index6–8vary rapidly beyond the range of analytical noise by up to 2.5 °C in 300 yr, showing hitherto unknown cycles with about 600-yr periodicities. Some of the changes parallel similar events in the oxygen isotope stratigraphy. SST oscillations may be linked, in part, to abrupt breakdowns in Atlantic deep-water ventilation resulting from meltwater events of Quaternary glacial terminations3,9,10.

The Interprocedural Coincidence Theorem

Abstract: We present an interprocedural generalization of the well-known (intraprocedural) Coincidence Theorem of Kam and Ullman, which provides a sufficient condition for the equivalence of the meet over all paths (MOP) solution and the maximal fixed point (MFP) solution to a data flow analysis problem This generalization covers arbitrary imperative programs with recursive procedures, global and local variables, and formal value parameters In the absence of procedures, it reduces to the classical intraprocedural version In particular, our stack-based approach generalizes the coincidence theorems of Barth and Sharir/Pnueli for the same setup, which do not properly deal with local variables of recursive procedures

Simultaneous fluorescence immunophenotyping and interphase cytogenetics: a contribution to the characterization of tumor cells.

Abstract: In immunocytochemical studies, the phenotypic evaluation of tumor cells is often complicated by accompanying normal cells, representing the original tissue or infiltrating leukocytes. This holds particularly true for tissues with a great morphological and immunophenotypical variability, such as bone marrow. A method that identifies mitotic tumor cells by chromosomal aberrations and permits the subsequent immunophenotypical analysis was a first progress, demonstrated by Teerenhovi et al. However, the results are usually hampered by the low number of analyzable mitoses. We demonstrate here a method that simultaneously combines immunophenotyping and in situ hybridization with centromere-specific probes. Using our method, numerically aberrant tumor cells can be identified by interphase cytogenetics and subsequently analyzed immunophenotypically. Since all interphase cells can be analyzed, we are not limited by the number and banding quality of analyzable mitoses.

Eddy dynamics in a primitive equation model: Sensitivity to horizontal resolution and friction

Abstract: A primitive equation model of an idealized ocean basin, driven by simple, study wind and buoyancy forcing at the surface, is used to study the dynamics of mesoscale eddies. Model statistics of a six-year integration using a fine grid (1/6° × 0.2°), with reduced coefficients of horizontal friction, are compared to those using a coarser grid (1/3° × 0.4°), but otherwise identical configuration. Eddy generation in both model cases is primarily due to the release of mean potential energy by baroclinic instability. Horizontal Reynolds stresses become significant near the midlatitude jet of the fine-grid case, with a tendency for preferred energy transfers from the eddies to the mean flow. Using the finer resolution, eddy kinetic energy nearly doubles at the surface of the subtropical gyre, and increases by factors of 3–4 over the jet region and in higher latitudes. The spatial characteristics of the mesoscale fluctuations are examined by calculating zonal wavenumber spectra and velocity autocorrelation functions. With the higher resolution, the dominant eddy scale remains approximately the same in the subtropical gyre but decreases by a factor of 2 in the subpolar areas. The wavenumber spectra indicate a strong influence of the model friction in the coarse-grid case, especially in higher latitudes. Using the coarse grid, there is almost no separation between the energetic eddy scale and the scale where friction begins to dominate, leading to steep spectra beyond the cutoff wavenumber. Using the finer resolution an inertial subrange with a k−3 power law begins to emerge in all model regions outside the equatorial belt. Despite the large increase of eddy intensity in the fine-grid model, effects on the mean northward transport of heat are negligible. Strong eddy fluxes of heat across the midlatitude jet are almost exactly compensated by changes of the heat transport due to the mean flow.

Science teachers’ use of analogies: observations from classroom practice

Abstract: The study was designed to examine how science teachers used analogies during their regular teaching routines to enable students to comprehend scientific concepts. A total of 40 lessons taught by seven different teachers were observed and analysed using an interpretive research methodology to develop four generalized observations. In this study the science teachers used few analogies, though both simple and enriched types were observed in their teaching. Interviews following classroom observations revealed that the teachers were knowledgeable about some of the beneficial and detrimental aspects of analogy use, and they considered that they used both analogies and examples as a regular part of their teaching, though it was observed that often they did not differentiate between examples and analogies. The research suggests that effective use of analogies in regular classroom science teaching needs to be based on a well‐prepared teaching repertoire of analogies, using specific content in specific contexts and...

R&D cooperation between firms—a perceived transaction cost perspective

Abstract: Transaction cost is considered as an explanatory variable for the choice between markets and various organizational arrangements for performing some predefined tasks, such as engaging in private R&D. With respect to R&D cooperation between firms, we show that the perception of high transaction cost is related to certain characteristics of the firm and to the type of R&D task. We also show a relationship between the perception of transaction cost and the perceived success of the cooperation. The analysis sheds light on various determinants of transaction costs.

The boundary currents in the western Argentine Basin

Abstract: A quasi-synoptic hydrographic data set enclosing the Brazil-Falkland (Malvinas) Confluence Zone is used to investigate the absolute geostrophic volume transports of the western boundary currents in the region. Water mass characteristics provide a basis for adjusting geostrophic shears near the continental margin at 38°S, and the depth-integrated southward transport there, comprised of the Brazil Current and deep boundary flow, is estimated to be 68 Sv (1 Sv = 10 6 m 3 s −1 ). Of this, 26 Sv are thermocline water, 18 Sv are Antarctic Intermediate Water, and 24 Sv are deep waters of circumpolar and North Atlantic origin. Assuming the bottom flow is parallel to the steep bathymetry at the western boundary of the Argentine Basin, a geostrophic transport of 143 Sv is found to move seaward across the 4600-m isobath between the latitudes of 38° and 46°S. Top-to-bottom northward transports in the region of the Falkland Current are then solved as residual quantities from mass balances for enclosed areas. The likelihood of significant northward bottom velocities in deep western boundary currents there, combined with there being no apparent reversals within the water column in the direction of flow, makes such a procedure necessary. The resulting estimates for the depth-integrated northward transports in the Falkland Current region are 75 Sv at 42°S and 88 Sv at 46°S. Approximately 60 and 70 Sv, respectively are contained in the upper 2000 m as a direct extension of the northern Antarctic Circumpolar Current, while 34 and 40 Sv are contained in the density range of surface and intermediate waters. The northward transports in layers beneath the 2000-m level belong to the deep western boundary currents of the southern Argentine Basin. These numbers for the Falkland Current region are much larger than the 10–20 Sv values typically found in the literature, but they are consistent with other information such as the volume transport in the upper 2000 m of the northern Antarctic Circumpolar Current in Drake Passage, velocities of surface drifters in the Falkland Current, and the full-depth circulation in the interior of the Argentine Basin.