Showing papers by "University of Bonn published in 1990"

Applied Nonparametric Regression

Abstract: Preface Part I. Regression Smoothing: 1. Introduction 2. Basic idea of smoothing 3. Smoothing techniques Part II. The Kernel Method: 4. How close is the smooth to the true curve? 5. Choosing the smoothing parameter 6. Data sets with outliers 7. Smoothing with correlated data 8. Looking for special features (qualitative smoothing) 9. Incorporating parametric components and alternatives Part III. Smoothing in High Dimensions: 10. Investigating multiple regression by additive models Appendices References List of symbols and notation.

Supercompilers for parallel and vector computers

Abstract: Table of Contents * Supercomputer and Supercompilers * Supercomputer Architectures * Scalar Analysis * Data Dependence * Standard Transformations * Vectorization * Parallelization * Supercompilers and their Environments * Appendices

Genetic mapping of chronic childhood-onset spinal muscular atrophy to chromosome 5q1 1.2–13.3

Abstract: SPINAL muscular atrophy (SMA) describes a group of heritable degenerative diseases that selectively affect the α-motor neuron. Childhood-onset SMAs rank second in frequency to cystic fibrosis among autosomal recessive disorders, and are the leading cause of heritable infant mortality. Predictions that genetic heterogeneity underlies the differences between types of SMA, together with the aggressive nature of the most-severe infantile form, make linkage analysis of SMA potentially complex. We have now analysed 13 clinically heterogeneous SMA families. We find that 'chronic' childhood-onset SMA (including intermediate SMA or SMA type II, and Kugelberg–Welander or SMA type III) is genetically homogeneous, mapping to chromosomal region 5ql 1.27#150;13.3.

Migration and orientation in anuran amphibians

Abstract: In anuran amphibians migratory behaviour is constrained by the demands of water balance and thermoregulation. Therefore, the migratory range of anurans amounts to 15 km at most. Adult anurans perform migrations, if important habitat resources (e.g. sites for reproduction, nutrition and hibernation) are spatially separated. Site fidelity to these spatial units is a common feature of most anurans. These general considerations are exemplified in the common European toad Bufo bufo. Directed movements such as migrations towards a breeding or home site require mechanisms of orientation. The spatial range of the homing ability coincides widely with the natural migratory range of each species. Many sensory systems are involved in the perception of orientation stimuli: the auditory, the olfactory and the visual system as well as the still unidentified system of magneto-perception. Vocalization of conspecifics, odours of ponds, landmarks, the positions of sun, moon and stars, polarization patterns of the sky and th...

Shape of the red edge as vitality indicator for plants

Abstract: The shift of the red edge in the reflection spectra of vegetation targets is a known phenomenon documenting changes in the biological status of plants. In our study we analysed the variability of red edge reflection in dependency of differently managed field plots, The results indicate that the red edge is not fully described by the shift of the main inflection point, but has to be considered as a collection of several different and possibly independent features, each of them influenced by biological parameters of the plants. Thus, taking all features, the red edge as derived from high resolution spectra may provide enough information to detect small differences in the chemical and morphological status of plants.

Haemophilia B: database of point mutations and short additions and deletions, 7th edition.

Abstract: The seventh edition of the haemophilia B database lists in easily accessible form all known factor IX mutations due to small changes (base substitutions and short additions and/or deletions of <30 bp) identified in haemophilia B patients. The 1535 patient entries are ordered by the nucleotide number of their mutation. Where known, details are given on: factor IX activity, factor IX antigen in circulation, presence of inhibitor and origin of mutation. References to published mutations are given and the laboratories generating the data are indicated.

Human Recombinant DNA–Derived Antihemophilic Factor (Factor VIII) in the Treatment of Hemophilia A

Abstract: Background. Current treatment of hemophilia A, a hereditary disorder affecting approximately 1 in 10,000 males, relies on plasma-derived factor VIII concentrates. We tested the safety and efficacy of a recombinant factor VIII preparation for the treatment of this disorder. Methods. We conducted the investigation in three stages: comparing the pharmacokinetics of plasma-derived and recombinant factor VIII, assessing the efficacy of recombinant factor VIII for home therapy, and assessing its efficacy for major surgical procedures and hemorrhage. A total of 107 subjects with hemophilia, 20 of whom had not been treated previously, enrolled in the investigation. Results. The in vivo recovery and elimination half-lives of recombinant factor VIII equaled or exceeded those of plasma-derived factor VIII. Seventy-six subjects participated in a home-treatment program, using recombinant factor VIII for 69 to 807 days (median, 618); home diaries of 56 subjects treated for 5 months were analyzed. Of 540 bleedi...

Chva´tal closures for mixed integer programming problems

Abstract: Chvatal introduced the idea of viewing cutting planes as a system for proving that every integral solution of a given set of linear inequalities satisfies another given linear inequality. This viewpoint has proven to be very useful in many studies of combinatorial and integer programming problems. The basic ingredient in these cutting-plane proofs is that for a polyhedronP and integral vectorw, if max(wx|x ∈ P, wx integer} =t, thenwx ⩽ t is valid for all integral vectors inP. We consider the variant of this step where the requirement thatwx be integer may be replaced by the requirement that\(\bar wx\) be integer for some other integral vector\(\bar w\). The cutting-plane proofs thus obtained may be seen either as an abstraction of Gomory's mixed integer cutting-plane technique or as a proof version of a simple class of the disjunctive cutting planes studied by Balas and Jeroslow. Our main result is that for a given polyhedronP, the set of vectors that satisfy every cutting plane forP with respect to a specified subset of integer variables is again a polyhedron. This allows us to obtain a finite recursive procedure for generating the mixed integer hull of a polyhedron, analogous to the process of repeatedly taking Chvatal closures in the integer programming case. These results are illustrated with a number of examples from combinatorial optimization. Our work can be seen as a continuation of that of Nemhauser and Wolsey on mixed integer cutting planes.

An FTIR study of the catalytic activity of a 85:15 Pt:Ru alloy for methanol oxidation.

Abstract: In situ Fourier Transform Infrared Spectroscopy is used to study the catalytic properties of a Pt/Ru alloy as compared to pure platinum. Spectra taken at different potentials show the different behaviour of both metals with respect to methanol adsorption and oxidation. In the potential region below 700 mV the presence of Ru atoms increases the electrocatalytic activity of platinum. In the case of the alloy the poisoning adsorbate COad is adsorbed to a less extent and its seems to be weaker bonded to the Pt/Ru than to the Pt surface.

The biosynthesis of ectoine

Abstract: The biosynthetic pathway of the novel compatible solute ectoine (1,4,5,6-tetrahydro-2-methyl-4-pyrimidine carboxylic acid) was studied in the two extremely halophilic eubacteria Ectothiorhodospira halochloris and Halomonas elongata. The pathway starts with the phosphorylation of l-aspartate and shares its first two enzymatic steps with the biosynthesis of amino acids of the aspartate family: aspartokinase and l-aspartate-β-semialdehyde dehydrogenase. Evidence is presented for the presence of the enzymes l-diaminobutyric acid transaminase and l-diaminobutyric acid acetyl transferase and for the new enzyme the ring-forming ectoine synthase.

Degradation of dibenzothiophene by Brevibacterium sp.DO

Abstract: Dibenzothiophene, a polycyclic aromatic sulfur heterocycle, represents as a model compound the organic sulfur integrated in the macromolecular coal matrix. A pure culture of a Brevibacterium species was isolated, which is able to use dibenzothiophene as sole source of carbon, sulfur and energy for growth. During dibenzothiophene utilization sulfite was released in a stoichiometrical amount and was further oxidized to sulfate. Three metabolites of dibenzothiophene degradation were isolated and identified as dibenzothiophene-5-oxide, dibenzothiophene-5-dioxide and benzoate by cochromatography, UV spectroscopy and gas chromatographymass spectrometry analyses. Based on the identified metabolites a pathway for the degradation of dibenzothiophene by Brevibacterium sp. DO is proposed.

Amyotrophic lateral sclerosis: Macro–EMG and twitch forces of single motor units

Abstract: Macro-EMG potentials (MEP)s and twitch contractions (spike-triggered-averaging) of single motor units (MUs) have been recorded in the first dorsal interosseus muscle (FDI) of 10 control subjects and 20 patients with amyotrophic lateral sclerosis (ALS). MUs over the full range of voluntary recruitment thresholds were studied. Patients with slightly affected FDIs (5) mainly showed MUs with enlarged MEPs and increased twitch forces. In contrast, the patients with more severely affected FDIs (15) revealed decreased twitch forces, especially in the MUs with higher thresholds. The corresponding MEPs could be enlarged as well as normal. It appears that MU sprouting and the resulting increase of twitch force can compensate for the loss of motoneuron in early stages of ALS. In more advanced stages, however, a decline of the force of the surviving MUs, especially of those with higher thresholds, seems to contribute to the progressive muscle weakness, in addition to the corticospinal degeneration and the reduction in the number of motoneurons.

Solutions for the Two-Phase Stefan Problem with the Gibbs—Thomson Law for the Melting Temperature

Abstract: The coupling of the Stefan equation for the heat flow with the Gibbs-Thomson law relating the melting temperature to the mean curvature of the phase interface is considered. Solutions, global in time, are constructed which satisfy the natural a priori estimates. Mathematically the main difficulty is to prove a certain regularity in time for the temperature and the indicator function of the phase separately. A capacity type estimate is used to give an Lx bound for fractional time derivatives.

Global jet properties at 14–44 GeV center of mass energy in e + e − annihilation

Abstract: Jet properties ine + e − annihilation at center of mass energies of 14, 22, 35 and 43.7 GeV were studied with the data collected in the TASSO detector at PETRA, using the same evaluation procedures for all the energies. The total hadronic cross section ratio for the center of mass energy interval 39–47 GeV was determined to be ℛ=4.11±0.05 (stat)±0.18(syst.) at $$\langle \sqrt s \rangle = 43 - 7$$ GeV. Corrected distributions of global shape variables are presented as well as the inclusive charged particle distributions for scaled momentum and transverse momentum. The center of mass energy evolution of the average sphericity, thrust, aplanarity and particle momentum is shown.

Spatial distribution of growth rates and of epidermal cell lengths in the elongation zone during leaf development in Lolium perenne L.

Abstract: Relative elemental growth rates (REGR) and lengths of epidermal cells along the elongation zone of Lolium perenne L. leaves were determined at four developmental stages ranging from shortly after emergence of the leaf tip to shortly before cessation of leaf growth. Plants were grown at constant light and temperature. At all developmental stages the length of epidermal cells in the elongation zone of both the blade and sheath increased from 12 μm at the leaf base to about 550 μm at the distal end of the elongation zone, whereas the length of epidermal cells within the joint region only increased from 12 to 40 μm. Throughout the developmental stages elongation was confined to the basal 20 to 30 mm of the leaf with maximum REGR occurring near the center of the elongation zone. Leaf elongation rate (LER) and the spatial distributions of REGR and epidermal cell lengths were steady to a first approximation between emergence of the leaf tip and transition from blade to sheath growth. Elongation of epidermal cells in the sheath started immediately after the onset of elongation of the most proximal blade epidermal cells. During transition from blade to sheath growth the length of the blade and sheath portion of the elongation zone decreased and increased, respectively, with the total length of the elongation zone and the spatial distribution of REGR staying near constant, with exception of the joint region which elongated little during displacement through the elongation zone. Leaf elongation rate decreased rapidly during the phase when only the sheath was growing. This was associated with decreasing REGR and only a small decrease in the length of the elongation zone. Data on the spatial distributions of growth rates and of epidermal cell lengths during blade elongation were used to derive the temporal pattern of epidermal cell elongation. These data demonstrate that the elongation rate of an epidermal cell increased for days and that cessation of epidermal cell elongation was an abrupt event with cell elongation rate declining from maximum to zero within less than 10 h.

The role of trehalose as a substitute for nitrogen-containing compatible solutes (Ectothiorhodospira halochloris)

Abstract: The halophilic phototrophic bacterium Ectothiorhodospira halochloris is able to synthesize both nitrogen-containing (betaine, ectoine) and nitrogen-free (trehalose) compatible solutes. In the absence of external ammonium and under nitrogen-limited growth conditions ectoine was metabolized and trehalose partly replaced betaine. The cytoplasmic trehalose concentration did not exceeded 0.5 mol/kg water (approx. 30% of total compatible solutes). A decreasing content of betaine in cells growing under nitrogen limitation is a result of decreased biosynthesis. Apparently, the betaine pool cannot be used as a nitrogen source, not even in a situation of total nitrogen depletion.

Congruence of total and perfused capillary network in rat brains.

Abstract: In awake normocapnic rats, the density of the total and of the perfused capillary network was determined in 10 brain areas. The density of perfused capillaries was measured by using fluorescein isothiocyanate (FITC) globulin or Evans blue as intravenous marker and by fluorescent microscopy. The density of morphologically existing capillaries was determined according to either the histochemical alkaline phosphatase method or a newly developed immunohistochemical fluorescent method that allows marking of the capillary wall constituent fibronectin with a primary antibody directed against fibronectin. This antibody is made visible by a second FITC-coupled antibody (indirect immunofluorescence). Comparison of perfused and existing capillary counts revealed high congruence when fluorescent results were compared. In contrast, the alkaline phosphatase technique yielded capillary counts that were consistently 30% lower than the fibronectin and the FITC globulin counts. The identity of the perfused and the morphologically existing capillary network could be confirmed by a newly developed double-staining technique. First, the perfused capillaries were quantified by intravascular Evans blue. Then, the existing capillaries were relocated in the same measuring field by the fibronectin technique. Such double staining resulted in identical capillary counts in 97% of all cases. The following conclusions have been reached: 1) Fluorescent methods show a perfusion of virtually all capillaries in the brain of the awake normocapnic rat. 2) The alkaline phosphatase technique appears to underestimate the capillary density in the rat brain.

Activation of the epileptic focus by transcranial magnetic stimulation of the human brain

Abstract: To establish whether transcranial magnetic stimulation is able to activate the primary epileptic focus preferentially, 13 patients who had medically intractable complex partial seizures were examined prior to surgical therapy. Single or a series of magnetic stimuli were applied to various regions of the skull. The effects of transcranial magnetic stimulation were monitored via subdurally implanted electrodes. In the process of presurgical evaluation, the dosage of anticonvulsant medication had been reduced in all patients but one. Transcranial magnetic stimulation was able to activate the epileptic focus (or foci) in 12 of the 13 patients. Distinct patterns of focal activation were observed in 3 patients who had several foci. No epileptiform potentials were induced outside epileptic foci, which had been identified by corticographic recordings. In one patient a complex partial seizure that was induced was identical to her habitual seizures. In another patient, a complete transition from a nonactive theta focus to a self-sustained epileptic focus occurred. A facilitation of epileptiform afterdischarge was seen with sequential stimulation. No adverse effects were either reported by the patients or observed by the investigators. In summary transcranial magnetic stimulation is able to activate the epileptic focus (or foci) and consequently may be an additional tool for the localization of epileptic foci in presurgical evaluation.

A measurement of global event shape distributions in the hadronic decays of the Z 0

Abstract: We present measurements of global event shape distributions in the hadronic decays of theZ0. The data sample, corresponding to an integrated luminosity of about 1.3 pb−1, was collected with the OPAL detector at LEP. Most of the experimental distributions we present are unfolded for the finite acceptance and resolution of the OPAL detector. Through comparison with our unfolded data, we tune the parameter values of several Monte Carlo computer programs which simulate perturbative QCD and the hadronization of partons. Jetset version 7.2, Herwig version 3.4 and Ariadne version 3.1 all provide good descriptions of the experimental distributions. They in addition describe lower energy data with the parameter values adjusted at theZ0 energy. A complete second order matrix element Monte Carlo program with a modified perturbation scale is also compared to our 91 GeV data and its parameter values are adjusted. We obtained an unfolded value for the mean charged multiplicity of 21.28±0.04±0.84, where the first error is statistical and the second is systematic.

Optimizing weakly triangulated graphs

Abstract: A graph is weakly triangulated if neither the graph nor its complement contains a chordless cycle with five or more vertices as an induced subgraph. We use a new characterization of weakly triangulated graphs to solve certain optimization problems for these graphs. Specifically, an algorithm which runs inO((n + e)n3) time is presented which solves the maximum clique and minimum colouring problems for weakly triangulated graphs; performing the algorithm on the complement gives a solution to the maximum stable set and minimum clique covering problems. Also, anO((n + e)n4) time algorithm is presented which solves the weighted versions of these problems.

Glomerular Hyperfiltration Indicates Early Target Organ Damage in Essential Hypertension

Abstract: In 111 patients with essential hypertension (World Health Organization stage I or II), we examined the relationship between renal hemodynamics and left ventricular hypertrophy. Left ventricular structure was determined by two-dimensional guided M-mode echocardiography, renal blood flow by iodine I 131 aminohippuric acid clearance, and glomerular filtration rate by creatinine clearance. The glomerular filtration rate correlated with left ventricular mass (r=.52) and left ventricular cross-sectional area (r=.21). Conversely, at a similar age, body mass index, body surface area, and arterial pressure, hypertensive patients with left ventricular hypertrophy disclosed a higher glomerular filtration rate and filtration fraction than those without left ventricular hypertrophy, whereas renal blood flow and renal vascular resistance measurements were not significantly different. Thus, at similar levels of arterial pressure and renal blood flow, glomerular hyperfiltration was linked to early cardiac structural changes in essential hypertension. We conclude that, in a hypertensive patient with normal renal function, a high glomerular filtration rate may be an indicator for early target organ damage in essential hypertension. (JAMA. 1990;264:2775-2780)

Involvement of presynaptic H3 receptors in the inhibitory effect of histamine on serotonin release in the rat brain cortex.

Abstract: Rat brain cortex slices or synaptosomes preincubated with 3H-serotonin were superfused with physiological salt solution (which, in the case of slices, contained citalopram, an inhibitor of serotonin uptake), and the effects of histamine and related drugs on the evoked tritium overflow were studied. The electrically (3 Hz) evoked tritium overflow from slices was inhibited by histamine and the H3 receptor agonists R-(-)-alpha-methylhistamine and N alpha-methylhistamine (pIC12.5 values: 6.41, 7.28 and 6.12, respectively), but not affected by the H1 receptor agonist 2-(2-thiazolyl)ethylamine and the H2 receptor agonist dimaprit (each at 10 mumol/l). The concentration-response curve for histamine was shifted to the right by the H3 receptor antagonists impromidine, burimamide and thioperamide (apparent pA2 values: 7.45, 5.97 and 7.88, respectively); the concentration-response curve of serotonin for its inhibitory effect on the electrically evoked overflow was not affected by the three drugs (apparent pA2 values: less than 5.5, less than 5.5 and less than 6.5). Given alone, impromidine, thioperamide and a low concentration of burimamide facilitated the electrically evoked overflow. In slices superfused with K(+)-rich, Ca2(+)-free solution containing tetrodotoxin throughout and in synaptosomes superfused with Ca2(+)-free solution, histamine inhibited the overflow evoked by introduction of Ca2+ (in synaptosomes, simultaneously with an increased amount of K+). In either tissue, the effect of histamine was counteracted by thioperamide. The results provide evidence that exogenous and probably also endogenous histamine inhibits serotonin release in the rat brain cortex via presynaptic histamine H3 receptors.