Showing papers by "University of Kiel published in 1991"

Automata on infinite objects

Abstract: Publisher Summary This chapter focuses on finite automata on infinite sequences and infinite trees. The chapter discusses the complexity of the complementation process and the equivalence test. Deterministic Muller automata and nondeterministic Buchi automata are equivalent in recognition power. Any nonempty Rabin recognizable set contains a regular tree and shows that the emptiness problem for Rabin tree automata is decidable. The chapter discusses the formulation of two interesting generalizations of Rabin's Tree Theorem and presents some remarks on the undecidable extensions of the monadic theory of the binary tree. A short overview of the work that studies the fine structure of the class of Rabin recognizable sets of trees is also presented in the chapter. Depending on the formalism in which tree properties are classified, the results fall in three categories: monadic second-order logic, tree automata, and fixed-point calculi.

The determination of the seismic quality factor q from vsp data: a comparison of different computational methods1

Abstract: Ten methods for the computation of attenuation have been investigated, namely: amplitude decay, analytical signal, wavelet modelling, phase modelling, frequency modelling, rise-time, pulse amplitude, matching technique, spectral modelling and spectral ratio. In particular, we have studied the reliability of each of these methods in estimating correct values of Q using three synthetic VSP seismograms for plane P-waves with different noise contents. The investigations proved that no single method is generally superior. Rather, some methods are more suitable than others in specific situations depending on recording, noise or geology. The analytical signal method has been demonstrated to be superior if true amplitude recordings are available. Otherwise spectral modelling or, in the ‘ noise-free’ case the spectral ratio method, is optimal. Finally, two field VSPs in sediments are investigated. Only in the case of the highest quality VSP can significant information be deduced from the computed attenuation.

Arabidopsis thaliana as a new model host for plant‐parasitic nematodes

Abstract: Summary We have established culture conditions for successful infection and development of several economically important cyst-forming and root-knot nematodes on Arabidopsis thaliana under monoxenic conditions. Complete life cycles were obtained with the sedentary cyst nematodes Heterodera schachtii, H. trifolii, H. cajani and the root-knot nematodes Meloidogyne incognita and M. arenariaas well as with the migratory nematode Pratylenchus penetrans. In contrast, H. goettingiana and Globodera rostochiensis were unable to develop on Arabidopsis roots. Tissue-culture quality agar and medium conditions optimized for hydroponic root culture were essential for successful infections. Detailed in-vivo observations were made inside Arabidopsis roots during the early infection stages of M. incognita and during complete development of H. schachtii. Seventy-four different ecotypes of Arabidopsis were screened for their susceptibility towards H. schachtii resulting in a range of infection rates. None of the ecotypes tested showed complete resistance in vitro. The use of Arabidopsis as a host for plant-parasitic nematodes will provide a new model system for the molecular genetic analysis of this interaction.

Ontogeny of the calcium binding protein parvalbumin in the rat nervous system.

Abstract: In the adult rat brain, the calcium-binding protein parvalbumin is preferentially associated with spontaneously fast-firing, metabolically active neurons and coexists with gamma-amino-butyric acid (GABA) in cortical inhibitory interneurons. Whether this is so in developing neurons has not been explored. To this end, we have used parvalbumin immunohistochemistry to study expression of this protein in the rat nervous system during pre- and postnatal life. Our results indicate that parvalbumin first appears at embryonic day 13 in sensory system of the spinal cord, in the vestibular (VIII), the trigeminal (V) and the visuomotor (III, IV, VI) systems, and develops rapidly during the following days. In these locations the expression of parvalbumin coincides with the beginning of physiological activity in nerve cells. In the gamma-aminobutyric acid (GABA)-containing interneurons of the cerebral cortex and the hippocampus, as well as in the Purkinje cells of the cerebellum, parvalbumin only appears postnatally. It lags behind the development of GABA-immunoreactivity by 1 to 2 weeks. The beginning of its expression, in the cerebellum at least, coincides with the arrival of excitatory synaptic input and the onset of spontaneous activity. Thus, during the development of the nervous system, the expression of parvalbumin is subordinate to the establishment of physiological activity.

Hydrographic Structure of the Convection Regime in the Gulf of Lions: Winter 1987

Abstract: Deep winter convection in the northwestern Mediterranean (Gulf of Lions) and the subsequent formation of Mediterranean Deep Water were observed using advanced oceanographic instrumentation during a six-week long experiment in 1987. The severe 1987 European winter forced an intense outbreak of the Mistral, a cold, dry wind blowing down the Rhone valley, in mid-January. Surface cooling and evaporation were of sufficient intensity to cause an initial episode of deep convection shortly before the experiment described here began. However, several more Mistral events took place during the experiment. During several cruises into the area, CTD and absolute horizontal velocity profiles were measured in the mixed area over the Rhone fan as well as across the southern front of this region; in addition, continuous records of shipboard meteorological and oceanographic parameters (air temperature, surface salinity, etc.) were made. An early-February Mistral apparently did not produce enough surface cooling to ...

Malignant peripheral neuroectodermal tumor and its necessary distinction from ewing's Sarcoma. A report from the kiel pediatric tumor registry

Abstract: A new classification scheme is proposed for the differential diagnosis of Ewing's sarcoma and malignant peripheral neuroectodermal tumor (MPNT) based on conventional light microscopic and immunohistochemical findings. The presence of Homer-Wright rosettes and/or the expression of at least two neural markers is diagnostic of MPNT Ewing's sarcoma. Ewing's sarcoma was diagnosed in cases lacking Homer-Wright rosettes and expressing no neural marker or only one in immunohistochemistry. Using this “new” approach considerable differences were found between both tumor types. Although most MPNT were located in the thoracopulmonary region, Ewing's sarcoma was located predominantly in the pelvis and extremities. The mean age of MPNT patients was greater than that of Ewing's sarcoma patients. Most importantly, however, was a statistically significant difference in prognosis: disease-free survival in Ewing's sarcoma patients at 7.5 years follow-up was 60% compared with 45% in MPNT patients (P = 0.026). The detection of HNK-1 in MPNT indicated a more aggressive biologic behavior, and the expression of protein S-100 appeared to be correlated with a more favorable clinical course. Cancer 68:2251–2259, 1991.

Intercalation and exchange reactions of clay minerals and non-clay layer compounds

Abstract: Presently, a large variety of layered materials are synthesized that are able to intercalate neutral guest molecules or to exchange inorganic and organic ions for interlayer ions. Several of these materials are also found as minerals.

The influence of numerical advection schemes on the results of ocean general circulation models

Abstract: The dependence of results from coarse-resolution models of the North Atlantic circulation on the numerical advection algorithm is studied. In particular, the sensitivity of parameters relevant for climate simulations as e.g., meridional transport of mass and heat and main thermocline thickness is investigated. Three algorithms were considered: (a) a central difference scheme with constant values for horizontal and vertical diffusion, (b) an upstream scheme with no explicit diffusion, and (c) a flux-corrected transport (FCT) scheme with constant and strictly isopycnal diffusion. The temporal evolution of the three models on time scales of centuries is markedly different, the upstream scheme resulting in much shorter adjustment time whereas the central difference scheme is slower and controlled by vertical diffusion rather than advection. In the steady state, the main thermocline structure is much less diffusive in the FCT calculation which also has much lower heat transport. Both horizontal circulation and overturning in the meridional-vertical plane are strongest in the upstream-model. The results are discussed in terms of the effective vertical (diapycnal) mixing in the different models. A significant increase in vertical resolution would be required to eliminate the high sensitivity due to the numerical algorithms, and allow physically motivated mixing formulations to become effective.

Reduction of Deepwater Formation in the Greenland Sea During the 1980s: Evidence from Tracer Data

Abstract: Hydrographic observations and measurements of the concentrations of chlorofluorocarbons (CFCs) have suggested that the formation of Greenland Sea Deep Water (GSDW) slowed down considerably during the 1980s Such a decrease is related to weakened convection in the Greenland Sea and thus could have significant impact on the properties of the waters flowing over the Scotland-Iceland-Greenland ridge system into the deep Atlantic Study of the variability of GSDW formation is relevant for understanding the impact of the circulation in the European Polar seas on regional and global deep water characteristics New long-term multitracer observations from the Greenland Sea show that GSDW formation indeed was greatly reduced during the 1980s A box model of deepwater formation and exchange in the European Polar seas tuned by the tracer data indicates that the reduction rate of GSDW formation was about 80 percent and that the start date of the reduction was between 1978 and 1982

Optimal Embeddings of Chaotic Attractors from Topological Considerations

Abstract: Guided by topological considerations, a new method is introduced to obtain optimal delay coordinates for data from chaotic dynamic systems. By determining simultaneously the minimal necessary embedding dimension as well as the proper delay time we achieve optimal reconstructions of attractors. This can be demonstrated, e.g., by reliable dimension estimations from limited data series.

Chlorofluoromethane and oxygen in the Eastern Mediterranean

Abstract: CFM-12 (chlorofluoromethane, CCl2F2) data from the 1987 expedition of the F.S. Meteor in the Eastern Mediterranean are presented and discussed in the context of simultaneous oxygen and hydrographic measurements. Taken together, these data strongly suggest that the Adriatic is the only substantial source of bottom and deep water for the Eastern Mediterranean, in that no signatures of Aegean-derived water are found in the Levantine and Ionian Basins below about 1200 m depth. On the basis of a CFM-12 budget, the time-averaged inflow rate of Adriatic deep water into the Ionian is estimated to be 0.3 ± 0.1 Sv. The lowest CFM-12 and oxygen concentrations are found in the deep water between 2800 and 1200 m depth. This water mass is considered the oldest water in the Eastern Mediterranean and appears to be renewed by upwelling of bottom water. A lens of high CFM-12 water centered near 700 m depth is observed at a single station (Sta. 756) south of Crete. According to multi-parameter water analysis this water originates in the Aegean (about 300 m depth). The form of the θ-S relation and the fact that the anomalous water was only observed at one station suggest that inflow of Aegean water occurs in the form of isolated lenses. The salinity distribution in 700 m depth, together with the anomaly at Sta. 756, indicates that water from the Aegean spreads out in the western Levantine and the Ionian between about 500 and 1200 m depth. We propose to denote this water mass Cretan Intermediate Water. Atlantic Water has CFM-12 concentrations in equilibrium with 1987 atmospheric concentrations everywhere in the Eastern Mediterranean, and oversaturations for both CFM-12 and oxygen are found in the seasonal thermocline above it. In contrast, Levantine Intermediate Water (LIW) is undersaturated for both oxygen and CFM-12, even in the presumed formation areas in the northeast Levantine.

A method to predict the mechanical strength of agricultural soils

Abstract: During a 3-year period the physical and mechanical properties of 37 typical, differently textured and structured agricultural soils in Bavaria were determined in order to predict their mechanical compressibility and trafficability. The soil physical properties (bulk density, pore size distribution, saturated hydraulic conductivity, air permeability and penetration resistance) and the soil mechanical properties (pre-consolidation load and the shear strength parameters angle of internal friction and cohesion), were determined on undisturbed, differently pre-dried soil samples (60 and 300 hPa water tension). In order to quantify the changes in soil physical properties affected by loading, all soil physical parameters were measured before and after loading by the confined compression test (load range 10–800 kPa). It was found that in homogeneous, non-structured soils, such as sands and silts with low clay content ( 15%, w/w), stability increased with increasing degree of aggregation (coherent > prismatic > blocky > subangular blocky), due to higher values of the angle of internal friction between the aggregates and higher values for the cohesion within the dense, stable aggregates. The mechanical soil strength, which is determined as the value of the pre-consolidation load, could be predicted by multiple regression analysis with a high degree of significance, when the shear parameters angle of internal friction and cohesion (load range 0–400 kPa) were included as independent variables.

A logistic mixture distribution model for polychotomous item responses

Abstract: The polychotomous Rasch model is generalized to a mixture distribution model. It is assumed that the observed data are generated by two or more latent classes of individuals so that within each class the polychotomous Rasch model holds but with different parameters between the classes. Hence, the proposed model is also a generalization of latent class analysis which allows for quantitative individual differences within the classes. A parameter estimation procedure is outlined, employing conditional inference methods for the item parameters within classes and the EM-algorithm for unmixing the data. The application of the model and control of model fit are illustrated by means of real data and simulated data.

Epstein–Barr virus and carcinomas: Undifferentiated carcinomas but not squamous cell carcinomas of the nasopharynx are regularly associated with the virus

Abstract: The Epstein-Barr virus (EBV) is consistently associated with undifferentiated nasopharyngeal carcinoma (NPC). There is, however, conflicting evidence as to whether squamous cell NPCs are also EBV-associated. Moreover, it has been proposed that other epithelial tumours, particularly thymomas and thymic carcinomas, should be included in the group of EBV-associated neoplasias. However, since the viral DNA in these studies was demonstrated only in extracted DNA, the cellular origin of the viral DNA is uncertain. We have therefore investigated 152 epithelial tumours from various sites for the presence of EBV-DNA by in situ hybridization with 35S-labelled probes. Sixty-eight of 77 undifferentiated NPCs showed an EBV-specific autoradiographic signal, thus confirming the strong association of this tumour type with EBV even in geographical areas where undifferentiated NPC is not endemic. None of eight squamous cell NPCs showed an EBV-specific signal. All of 15 carcinomas with a similar morphology to undifferentiated NPC but from different anatomic sites (thymus, tonsil, breast) were EBV-negative as were 9 thymomas, 26 squamous cell carcinomas of the palatine tonsil, and 14 cervical carcinomas. Our results therefore suggest a unique association of EBV with undifferentiated NPC and support concepts assigning different biological properties to undifferentiated NPC as compared with squamous cell NPC.

Scheduling of Project Networks by Job Assignment

Abstract: A recurring problem in project management involves the allocation of scarce resources to the individual jobs comprising the project. In many situations such as audit scheduling, the resources correspond to individuals skilled labour. This naturally leads to an assignment type project scheduling problem, i.e. a project has to be processed by assigning one of several individuals resources to each job. In this paper we consider the nonpreemptive variant of a resource-constrained project job-assignment problem, where job durations as well as costs depend upon the assigned resource. Regarding precedence relations as well as release dates and deadlines, the question arises, to which jobs resources should be assigned in order to minimize overall costs. For solving this time-resource-cost-tradeoff problem we present a hybrid brand and bound/dynamic programming algorithm with a rather efficient Monte Carlo type heuristic upper bounding technique as well as various relaxation procedures for determining lower bounds. Computational results are presented as well.

Hydrothermal activity and metallogenesis in the Lau back-arc basin

Abstract: IN 1989, the submersible Nautile discovered one of the most active hydrothermal fields on the modern ocean floor, in the Lau back-arc basin (Fig. 1). The field contains high-temperature white and black smokers, and as we report here, its characteristics contrast strongly with those of the hydrothermal fields found at normal mid-ocean ridges. The main differences are the acidity (pH as low as 2), chemistry and temperature (up to 400 °C) of the hydrothermal fluids, the composition of the ore deposits, and the volcanic and tectonic environments. The fluids also have very high concentrations of trace metals, and primary gold is present in the accompanying mineral deposits. Our data show that these back-arc deposits in the Lau Basin are intermediate between typical mid-ocean-ridge mineralization and massive sulphide deposits of the Kuroko type.

Poroelasticity: parameters reviewed

Abstract: SUMMARY Deformation of porous rocks is investigated by experts of various fields. This is probably the reason why poroelastic parameters are neither uniformly defined nor represented by standard symbols in the literature, and why inconsistencies have appeared in some publications. This paper is intended to clarify the use of material properties in order to facilitate application of poroelasticity theory. The key parameters referenced from a selection of mostly recent papers are: drained and undrained moduli and Poisson ratios, grain and pore compressibilities, the coefficient of effective stress, the Skemption ratio (pore pressure parameter), storage parameters, the Darcy conductivity, and the hydraulic diffusivity. The latter parameter governs the diffusional behaviour of poroelastic processes, as has been demonstrated by Rice & Cleary (1976). Herein, their formulation of the theory is used. References to Biot's (1941) parameters, which may be more familiar to some researchers, are given for completeness. A variety of extensions of the theory that have been elaborated by others is outlined in the last section.

Chemotherapy compared with bone marrow transplantation for adults with acute lymphoblastic leukemia in first remission.

Abstract: ▪ Objective: To compare efficacy of intensive postremission chemotherapy with allogeneic bone marrow transplantation in adults with acute lymphoblastic leukemia (ALL) in first remission. ▪ Design: ...

Glacial pCO2 Reduction by the World Ocean: Experiments With the Hamburg Carbon Cycle Model

Abstract: Possible mechanisms for the 80 ppm reduction of atmospheric CO2 partial pressure during the last glaciation were investigated using the Hamburg Ocean Carbon Cycle Model. The three-dimensional carbon cycle model is based on the velocity field of the Hamburg Large-Scale Geostrophic Ocean General Circulation Model and uses the same grid as that model. The horizontal resolution (3.5° × 3.5°) is lower than the length scale of narrow upwelling belts which could not be represented adequately in this study, but the large-scale features of the ocean carbon cycle are reproduced rather well. Sensitivity experiments were carried out to investigate the role of chemical and biological parameters (nutrient cycling, composition of biogenic particulate matter, CO2 solubility) and different circulation regimes for the atmospheric CO2 content. The model responses were compared to deep-sea sediment core records and ice core data from the last glaciation. Each experiment was compared with observed average tracer patterns during 18–65 kyr B.P. It was found that none of the sensitivity experiments alone could explain all observed tracer changes (atmospheric pCO2, Δδ13Cplanktonic-benthic, δ13Cbenthic differences, CaCO3 corrosivity indices) simultaneously, even in a qualitative sense. Thus according to the model none of the scenarios tested proves to be completely acceptable. The residual discrepancies between the observed and modeled tracer records can probably be attributed to the as yet inadequate reconstruction of the glacial ocean circulation. It is therefore suggested that more effort should be devoted to realistically reproducing the ice age ocean circulation field making use of the forthcoming glacial radiocarbon data base. The residuals between the realistically modeled and observed carbon cycle tracers (δ13C, CaCO3 saturation) should then reveal more clearly the real cause for the observed pCO2 decrease in the glacial atmosphere.

Hysterectomy via laparotomy or pelviscopy. A new CASH method without colpotomy

Abstract: Total Hysterectomy has been until non performed by extracervical "enucleation" of the fascia of the uterine corpus with amputation of the vagina. The new method leaves the extrafascial highly vascularised vascular stem, the corresponding nerves and the topography of the ureter untouched. It is limited to an intrafascial cylindriform enucleation of the cervix. The diameter of the cervical cylinder can be determined beforehand by vaginal sonography. Punching-out is effected from a new instrument C.U.R.T. (= calibrated uterine resection tool) of 10-20 mm diameter. A cervicohaemostaser provides for safe transvaginal haemostasis in the residual cervix. The transvaginal sexual sensations of the patient are not impaired due to the fact that the cardinal ligaments are preserved as well as the nerve supply of the cervical fascia. Suspension of the cervical fascia at the supporting ligaments of the uterus can be performed in an ideal manner. Pelviscopic extirpation of the uterus is done in the classical way used in abdominal hysterectomy with ligature and suture. Morcellated cylinders of 2-3 cms in diameter, of the cervix and corpus uteri and even of myomas up to the size of a child's head, will suffice for relevant histological examination. The physical stress to which the patient is exposed is about the same as in routine surgical pelviscopy. The abdominal space remains practically unopened in pelviscopic transabdominal hysterectomy. Pelviscopic transabdominal hysterectomy with and without adnexae according to the CASH technique corresponds to surgery performed with a minimum of invasiveness. It is fully sufficient as regards cancer prophylaxis with respect to cervical or endometrial cancer.

Hydrothermal activity in the Lau back-arc basin:Sulfides and water chemistry

Abstract: The submersible Nautile completed 22 dives during the Nautilau cruise (R/V Nadir, April 17-May 10, 1989) for a detailed investigation of the southern Lau basin near Tonga. The objective of the scientific team from France, Germany, and Tonga was to understand the process of sea-floor ore formation associated with hydrothermal circulation along the Valu Fa back-arc ridge behind the Tonga- Kermadec trench. The four diving areas, between lat 21°25′S and 22°40′S in water ∼2000 m deep, were selected on the basis of results from cruises of the R/V JeanCharcot and R/V Sonne. The Nadir cruise provided proof of hydrothermal activity—in all four areas, over more than 100 km—as indicated by the widespread occurrence of hydrothermal deposits and by heat flow, conductivity, and temperature measurements near the sea bottom. The most spectacular findings were high-temperature white and black smokers and associated fauna and ore deposits. Hydrothermal water chemistry and sulfide composition data presented here indicate that this hydrothermal field is very different from the hydrothermal fields in oceanic ridges. This difference is seen in the water chemistry of the hydrothermal fluid (pH = 2 and high metal content) and the chemical composition of sulfides (enrichment in Ba, As, and Pb).