Showing papers by "Karlsruhe Institute of Technology published in 1988"

The Role of Chlorophyll Fluorescence in The Detection of Stress Conditions in Plants

Abstract: (1988). The Role of Chlorophyll Fluorescence in The Detection of Stress Conditions in Plants. C R C Critical Reviews in Analytical Chemistry: Vol. 19, No. sup1, pp. S29-S85.

Role of underrelaxation in momentum interpolation for calculation of flow with nonstaggered grids

Abstract: (1988). ROLE OF UNDERRELAXATION IN MOMENTUM INTERPOLATION FOR CALCULATION OF FLOW WITH NONSTAGGERED GRIDS. Numerical Heat Transfer: Vol. 13, No. 1, pp. 125-132.

A progress report on the status of the COLUMBUS MRCI program system

Abstract: The COLUMBUS program system is a collection of Fortran programs for performing general multireference single- and double-excitation configuration interaction (MRSDCI) wave function optimization based on the graphical unitary group approach. The program system also includes integral generation, SCF and MCSCF orbital optimization, integral transformation, and wave function analysis programs. The original program system was written in 1980 to 1981. Since that time, it has evolved into one of the most popular MRSDCI program systems used in the computational chemistry community. The discussion of this evolution will include the exploitation of efficient matrix-matrix and matrix-vector product computational kernels, the use of generally contracted symmetry-adapted orbital basis sets, general Hamiltonian diagonalization procedures, energy-based internal walk selection, flexible DRT specification, improved coupling-coefficient evaluation methods, coupled-pair functional and multireference CPF capabilities, and density matrix construction. The numerous versions of the program system that are maintained at different sites and on different computers are now in the process of being merged. The source code for this combined version will be made available to the computational chemistry community. The source code for a specific computer may be generated from the source code for another computer by a single pass through a simple filter utility that is included with the program system. The directly supported computers will initially include various models of VAX, Cray, FPS, IBM, CDC, and ETA machines with the addition of other machines shortly thereafter. The ongoing developments of the COLUMBUS system that are discussed include a new method for computing analytic energy gradients for MRSDCI wave functions. This effective-density-matrix based method avoids the “coupled perturbed MCSCF” solutions for each coordinate direction, avoids the transformation of any derivative-integral quantities from the AO to the MO basis, avoids the transformation of the coupling coefficients from the MO to the AO basis, allows a subset of the MCSCF doubly occupied orbitals to be frozen in the CI wave function, and allows the MRSDCI wave function to be generated from general reference CSFs that are not necessarily related to the MCSCF expansion CSFs.

Faster 4 × 4 matrix method for uniaxial inhomogeneous media

Abstract: An exact representation of the transfer matrix for stratified homogeneous uniaxial media is derived. It can be used to calculate optical quantities such as reflectance and transmittance by means of Berreman’s 4 × 4 matrix method, permitting calculations for thick homogeneous slabs such as polarizers in one single step without the commonly used truncated series expansion. When the dielectric tensor of an inhomogeneous medium varies continuously with the normal to the plane of stratification, the medium is divided into thin slabs. The transfer matrix of the whole medium is then obtained by multiplying the transfer matrices of all slabs. Treating each slab as homogeneous gives satisfactory results, as shown in an example of a periodic structure for which an analytic solution is known.

In Vivo Chlorophyll Fluorescence as a Tool for Stress Detection in Plants

Abstract: A definition of stress to plants and a general stress concept are presented including a list of possible major natural and anthropogenic stress factors. It is shown that the white light or laser-induced chlorophyll fluorescence of predarkened leaves is a very suitable tool for early stress detection in plants as well as for regeneration studies. The different chlorophyll fluorescence parameters to be measured are: variable fluorescence (ratio fmax/fo), the vitality index (fluorescence decrease ratio, Rfd-values), the stress adaption index Ap, the fluorescence spectra (ratio F690/F735) and the photochemical Q- and non-photochemical E-quenching (qQ and qE). Some examples of the measurement of these parameters under stress conditions are given.

Multiple distributions for biased random test patterns

Abstract: An efficient method has been presented to compute multiple distributions for random patterns, which can be applied successively. Using multiple distributions, all combinational circuits can be made random-testable, and complete fault coverage is provided by a few thousands of random patterns. The differently weighted random test sets can be applied to scan path circuits using an external chip, combining the advantages of a low cost test and of high fault coverage. Several facts about testing by random patterns have been proven. It has been shown that the number of random patterns required for a certain fault coverage can be computed without regarding the pseudorandom property and with the independence assumption for fault detection. >

Effects of the separating shear layer on the reattachment flow structure part 2: Reattachment length and wall shear stress

Abstract: Measurements of reattachment length of a separated flow behind a backward-facing step for a range of Reynolds numbers (8000 < ReH < 40,000) and initial boundary-layer thickness (0 < δ/H < 2) were performed with the purpose of explaining the scatter in existing (high quality) data sets and to understand the effect of the initial shear-layer structure on the reattachment zone. The reattachment length for the case of laminar boundary layers upstream of the step were 30% smaller than when the boundary layer upstream of the step was turbulent. Measured values of the mean wall shear stress in the reattachment zone were also measurably affected by the upstream boundary-layer state. The (rms) levels of fluctuating wall stress were not sensitive to boundary-layer state, but rather to δ/H, as was the case for the pressure profiles in part 1 (Adams and Johnston 1988).

Molecular cloning, heterologous expression, and primary structure of the structural gene for the copper enzyme nitrous oxide reductase from denitrifying Pseudomonas stutzeri.

Abstract: The nos genes of Pseudomonas stutzeri are required for the anaerobic respiration of nitrous oxide, which is part of the overall denitrification process. A nos-coding region of ca. 8 kilobases was cloned by plasmid integration and excision. It comprised nosZ, the structural gene for the copper-containing enzyme nitrous oxide reductase, genes for copper chromophore biosynthesis, and a supposed regulatory region. The location of the nosZ gene and its transcriptional direction were identified by using a series of constructs to transform Escherichia coli and express nitrous oxide reductase in the heterologous background. Plasmid pAV5021 led to a nearly 12-fold overexpression of the NosZ protein compared with that in the P. stutzeri wild type. The complete sequence of the nosZ gene, comprising 1,914 nucleotides, together with 282 nucleotides of 5'-flanking sequences and 238 nucleotides of 3'-flanking sequences was determined. An open reading frame coded for a protein of 638 residues (Mr, 70,822) including a presumed signal sequence of 35 residues for protein export. The presequence is in conformity with the periplasmic location of the enzyme. Another open reading frame of 2,097 nucleotides, in the opposite transcriptional direction to that of nosZ, was excluded by several criteria from representing the coding region for nitrous oxide reductase. Codon usage for nosZ of P. stutzeri showed a high G + C content in the degenerate codon position (83.9% versus an average of 60.2%) and relaxed codon usage for the Glu codon, characteristic features of Pseudomonas genes from other species. E. coli nitrous oxide reductase was purified to homogeneity. It had the Mr of the P. stutzeri enzyme but lacked the copper chromophore.

Enclathration of helium in ice II: the first helium hydrate

Abstract: The hydrates of the heavier noble gases Ar, Kr and Xe are easy to prepare, and they crystallize in two different structures1. The corresponding hydrates of He and Ne apparently do not exist. We now find by neutron powder diffraction experiments that, when applying He gas pressures of > 0.28 GPa, a gas hydrate with the idealized formula He · 6D20 is formed. The He content varies with the applied He pressure as expected of an ideal solution behaviour with a Langmuir constant of 0.07 (1) GPa−1. The host lattice of this first well-characterized He-clathrate is very similar to ice II. The He enclathration stabilizes the ice II structural framework and hampers the formation of ice III, V and IX.

Physical training intervention in female shift workers: I. The effects of intervention on fitness, fatigue, sleep, and psychosomatic symptoms.

Abstract: A physical training intervention was carried out on 75 nurses and nursing aides working irregular shifts to determine the effects of such an intervention on health, sleep-wakefulness and adaptation to shiftwork. The study design and changes in physical fitness, fatigue, sleep and psychosomatic symptoms are examined. Training (T) and control (C) groups were built randomly from matched sets of subjects. Questionnaire, laboratory and field studies were done before and after a controlled physical training programme lasting four months. Maximal oxygen consumption and muscle strength increased and heart rates at rest and at work decreased significantly in the T but not in the C group. General fatique during the shift cycle, and fatigue during the night shifts were reduced, whereas fatigue during the evening shifts increased owing to the intervention. Sleep length increased slightly and musculoskeletal symptoms were reduced. The results suggest that moderate physical training increases the physical fitness of fe...

A similarity approach to turbulent sediment-laden flows in open channels

Abstract: A basis is developed for a similarity treatment of the coupled mean fields in turbulent open-channel flows over a flat sand bed in equilibrium with a suspension of sand. Hypotheses involving multiple scales, asymptotic similarity, and matching over an overlapping region are made instead of the traditional dependence on eddy diffusion and Reynolds analogies. Velocity measurements using the laser-Doppler technique in experiments with well-sorted natural sands showed that, contrary to the implications of previous models, the effect of suspended sediment on the mean velocity profile may, over a variety of laboratory conditions, be confined to a layer adjacent to the bed. This is interpreted within the similarity framework in terms of the existence of an inner lengthscale, differing from either the viscous or the grain scale, associated with the presence of sediment. The suggested lengthscales and concentration scales are examined in light of the experimental results.

Concepts, processing and results

Abstract: Investigations have been carried out in the Wadi Araba–Jordan Graben area to trace the relationship between diagnostic signals received from Landsat Thematic Mapper (TM) data and several mineralized ground districts To meet the objectives, different approaches, involving ratioing, principal component analysis and IHS-decorrelation processing, are used to enhance diagnostic features associated with hydrothermally altered areas Using ratio techniques the best suited approach is given by a colour combination of band ratios 5/7, 4/3 and 7/4 In principle, comparable results can be generated by a combination of the principle components (PCs) 2, 4 and 3 in this succession However, the ratio and PC approaches often fail to accentuate clearly the diagnostic features Main reasons are attributable to similarities in relative intensities of vegetation and minerals and to disadvantages that arise through the techniques themselves Decorrelated and filtered colour composites of TM bands 1, 4 and 7 have pr

Image sequences—ten (octal) years—from phenomenology towards a theoretical foundation

Abstract: Many investigations of image sequences can be understood on the basis of a few concepts for which computational approaches become increasingly available. The estimation of optical flow fields is discussed, exhibiting a common foundation for feature-based and differential approaches. The interpretation of optical flow fields is mostly concerned so far with approaches which infer the 3-D structure of a rigid point configuration in 3-D space and its relative motion with respect to the image sensor from an image sequence. The combination of stereo and motion provides additional incentives to evaluate image sequences, especially for the control of robots and autonomous vehicles. Advances in all these areas lead to the desire to describe the spatio-temporal development recorded by an image sequence not only at the level of geometry, but also at higher conceptual levels, for example by natural language descriptions.

O-Sr isotopic variations in Miocene granitoids from the Aegean: evidence for an origin by combined assimilation and fractional crystallization

Abstract: Sr, O, and D/H isotopic compositions have been analyzed in Miocene metaluminous to slightly peraluminous (I-type) granitoids of the central Aegean. Individual plutonic complexes display significant variations in their δ18O and initial87Sr/86Sr compositions.δD and δ18O compositions of minerals and whole-rocks are mostly in the magmatic range. Some samples from Naxos and Mykonos/Delos show low δD and δ18O values characteristic of meteoric-water-hydrothermal interaction, but as a whole the changes in δ18O and Sr isotopic compositions as a result of hydrothermal alteration were slight, even in instances where marked alteration is petrographically observable. Consequently, the bulk-rock variations of δ18O from 8.1‰ to 12.0‰ and of87Sr/86Sr from 0.70438 to 0.71450 may be regarded as primary and indicative of the conditions of their evolution. Heterogeneous isotopic compositions observed in the individual plutons of Serifos, Ikaria, Samos and Kos may be caused by the multiple intrusion of chemically and isotopically distinct magma pulses, with high viscosities and relatively rapid consolidation in most cases preventing complete homogenization. The granitoids of Serifos, Ikaria and Kos display weak correlations between the initial87Sr/86Sr and δ18O and 1/Sr. The granitoid province shows a positive correlation between87Sr/86Sr and δ18O and a non-linear relationship between87Sr/86Sr and 1/Sr, whereby 1/Sr increases more rapidly than the isotopic ratio as the degree of fractionation of the rocks increases. It is argued that assimilation of older continental material by mantle-derived arc magmas with combined fractionation (AFC) is the most plausible model to explain the chemical and isotopic characteristics of the granitoids and the geological situation in which rock-types trend from granodiorites in the (south)west, near the inferred Oligocene-Miocene suture, to granites in the center and monzonites in the (north)east of the province.

Combustion and Diffusion Flames at High Pressures to 2000 bar

Abstract: The combustion of methane with oxygen in supercritical homogeneous aqueous fluids has been investigated and stationary diffusion flames generated to pressures of 2000 bar. A reaction autoclave with sapphire windows contains high pressure homogeneous mixtures of water and methane to 500°C. A typical mixture composition is 70 to 30 mole percent of H2O and CH4. A quasi-circular fluid flow permits the steady injection of oxygen through a 0.5 mm nozzle at rates of 1 — 10 mm3 s−1 at constant pressures. — Above 400°C spontaneous ignition of flames occurred. The flames were observed and recorded with microscope and video camera. Emission spectra in the UV-region were obtained and samples could be taken for analysis. Below about 400°C flame-less oxidation is detected. The stationary diffusion flames are cone-shaped and typically about 3 mm high. Flame examples for pressures between 300 and 2000 bar are shown. Preliminary temperatures derived from OH-spectra are close to 3200 K. — Water can be replaced by argon.

Progressive Taxation and Redistributive Taxation: Different Labels for the Same Product?

Abstract: The paper examines different approaches to measure tax progressivity. In particular the distributional aspect of taxation is considered in some depth. For each member of a parametric class of inequality concepts, including more than only the relative and the absolute view of inequality, a necessary and sufficient condition for a tax function to be inequality reducing with respect to this concept for all admissible pre-tax income distributions is derived, both in strong and weak form. Only three very natural properties are required to prove this result: each tax liability is less than the corresponding pre-tax income, taxation does not reverse ranks on the income scale, and inequality is reduced if a rich gives to a poor such that they do not interchange their ranks. A definition of tax progressivity based on the shown equivalence is suggested. It is demonstrated that inequality reducing taxation is equivalent to progressive taxation in the sense of an increasing average tax rate if and only if the concept of relative inequality is used.

The chlorophyll fluorescence ratio f690/f735 as a possible stress indicator

Abstract: The chlorophyll fluorescence emission spectra, as excited by blue and red light including laser light, were determined depending on the chlorophyll content and the photosynthetic activity of leaves and needles. The fluorescence-emission spectra exhibit two maxima or a shoulder in the 690 nm and the 735 nm region. The corresponding fluorescence ratio F690/F735 for green leaves is higher (values of 0.8 to 1.1) when excited with blue light (range 400 to 500 nm) than excited with light in the yellow to red wavelength region (525 to 633 nm), which only yields values for F690/F735 of 0.5 to 0.7. The values for the ratio F690/F735 are drastically increased with decreasing chlorophyll content of leaves and to a lower degree also by a decline of photosynthetic activity (e.g. herbicide treatment, needles of damaged forest trees) no matter whether the fluorescence is excited by red or blue light. Since stress induces a lower chlorophyll content as well as lower rates of photosynthesis, the ratio F690/F735 can be taken as indicator of stress to plants. The application of the ratio F690/F735 in detecting stress to terrestrial vegetation via remote sensing of the chlorophyll fluorescence is discussed.

Defects in cytochrome cd1-dependent nitrite respiration of transposon Tn5-induced mutants from Pseudomonas stutzeri

Abstract: Mutants with defective respiratory nitrite utilization (Nir- phenotype) were obtained by transposon Tn5 insertion into genomic DNA of the ZoBell strain of Pseudomonas stutzeri. Three representative mutants were characterized with respect to their activities of nitrite and nitric oxide reduction, cytochrome cd 1 content, and pattern of soluble c-type cytochromes. Mutant strain MK201 over-produced cytochrome c 552 about fourfold by comparison with the wild type, but possessed an in vitro functional cytochrome cd 1. Mutant strain MK202 lacked cytochrome cd 1 and, simultaneously, had low amounts of cytochrome c 552 and the split α-peak c-type cytochrome. Strain MK203 synthesized nitrite reductase defective in the heme d 1 prosthetic group. Irrespective of these biochemically distinct Nir- phenotypes, all mutants preserved the nitric oxidereducing capability of the wild type. The mutant characteristics demonstrate that cytochrome cd 1 is essential for nitrite respiration of P. stutzeri and establish the presence of a nitric oxide-reducing system distinct from cytochrome cd 1. They also indicate the functional or regulatory interdependence of c-type cytochromes.