Showing papers by "Karlsruhe Institute of Technology published in 1992"

Technological interweavement: a means of achieving innovation success

Abstract: In this paper, results are presented of an empirical study of the Lake Constance region covering a sample of 848 manufacturing companies. Based upon multivariate analyses, the paper documents that the mobilization of external resources and know-how is a critical factor for a firm’s technological innovation success which in turn is the main determinant of commercial innovation success. The findings show that there are three kinds of technology-oriented external relationships, which prove to be of special importance: close contacts with customers, linkages to universities and research institutes and R&D-cooperations with other companies. innovation-pressure and raising expenditures for R&D accompanied by shortening product-life-cycles and time based competition. Especially in regard to innovation, relationships have potentials shown neither by market nor by hierar~hy:~ 0 Synergy effects of value: The combination of internal and external resources can result in a multicompetence-effect, which facilitates the development of products of superior quality. Furthermore, relationships constitute an instrument to reduce redundancies (e.g. parallel research activities) and accelerate innovation processes.

The crystal barrel spectrometer at LEAR

Abstract: The crystal Barrel spectrometer used at LEAR, CERN to study the products of pd annihilations is described. A 1380 element array of Csl crystals measures photons from the decay of π0, η, η′ and ω mesons. A segmented drift chamber in a 1.5T magnetic field is used to identify and measure charged particles. A fast on-line trigger on charged and neutral multiplicities and on the invariant mass of secondary particles is available. The performance of the detector is discussed.

Tobacco and alcohol and the risk of head and neck cancer

Abstract: We carried out two case-control studies on the relative risk of head and neck cancer in association with tobacco and alcohol consumption. The first study carried out at the ENT Department of the University hospitals of Heidelberg and Giessen (FRG) comprised 200 male patients with squamous cell cancer of the head and neck and 800 control subjects matched for sex, age, and residential area (1:4 matching design). Of the tumour patients, 4.5% had never smoked, in contrast to 29.5% of the control group. The average tobacco and alcohol consumption of the patients was approximately twice as high as in the control subjects. The highest alcohol and tobacco consumption was observed in patients suffering from oropharyngeal cancer. Tobacco and alcohol increased the risk of head and neck cancer in a dose-dependent fashion and acted as independent risk factors. In heavy smokers (> 60 pack-years) a relative risk of 23.4 (alcohol adjusted) was calculated. Combined alcohol and tobacco consumption showed a synergistic effect. The risk ratio increased more in a multiplicative than in an additive manner. Oral and laryngeal cancer were associated with the highest tobacco-associated risk values. The highest ethanol-associated risk values were associated with oropharyngeal and laryngeal cancer. The second study was carried out at the ENT Department of the University of Heidelberg on 164 males with squamous cell carcinoma of the larynx and 656 control subjects matched for sex, age and residential area (1:4 matching design). Of the cases, 4.2% had never smoked, compared with 28.5% of the control subjects. The risk of laryngeal cancer by tobacco consumption was dose dependent, reaching a maximum value of 9.1 (adjusted for alcohol) for a consumption of more than 50 tobacco-years (TY). The relative risk of laryngeal cancer associated with alcohol intake was also dose dependent, reaching a value of 9.0 (adjusted for tobacco) for a mean daily consumption of more than 75 g alcohol. An analysis of subsite specific risks showed that heavy smokers (> 50 TY) carried a nearly ten times higher risk of supraglottic cancer than of glottic cancer. The risk of supraglottic cancer from alcohol consumption was also higher than that of glottic cancer.

Direct computation of second-order SCF properties of large molecules on workstation computers with an application to large carbon clusters

Abstract: The ab initio SCF computation of second-order properties of large molecules (with 50 atoms or more) on workstation computers is demonstrated for static dipole polarizabilities and nuclear magneting shieldings. The magnetic shieldings are calculated on the basis of gauge including atomic orbitals (GIAO). Algorithmic advances (semi-direct algorithms with efficient integral pre-screening, and use of a quadratically convergent functional for the polarizabilities) are presented together with an illustrative application to the fullerenes C60 and C70.

Estimation procedure for the Weibull parameters used in the local approach

Abstract: The local approach was recently proposed by Beremin and Mudry for evaluating the statistical behaviour of toughness results of materials. This approach introduces a stress parameter σ w , termed the Weibull stress, as a measure of the fracture resistance of materials instead of the conventional toughness parameters such as K c, δ c and J cl (critical stress intensity factor, CTOD and J-integral, respectively). The Weibull stress σ w obeys the Weibull distribution with the two parameters m and σ u (the shape and the scale parameter, respectively). The first parameter m is normally estimated to be 22 irrespective of the kind of material. In this paper a procedure for the determination of the Weibull parameters m and σ u is developed. This procedure consists of the determination of the plastic zone ahead of the crack tip, from which cleavage fracture originates, and of the maximum likelihood estimation of the parameters m and σ u based on the stress distribution in the plastic zone. Calculations using this procedure confirm that the distribution of the Weibull stress σ w is a material property independent of specimen thickness, and in particular that the shape parameter m depends on the material, e.g. m≃12 for a German reactor pressure vessel steel (20 Mn Mo Ni 5 5). Using these parameters for the distribution of the Weibull stress the size effect in fracture toughness values is predicted and an improved agreement between theory and experiments is obtained compared to the Weakest Link model.

A comparative EPR investigation of the multicopper proteins nitrous‐oxide reductase and cytochrome c oxidase

Abstract: The multicopper proteins, nitrous-oxide reductase (N2OR) and cytochrome c oxidase (COX), were investigated by EPR spectroscopy at microwave frequencies 2.4-35 GHz. Our results support a Cu-Cu interaction in COX and N2OR. At least 10 lines in the 2.7-GHz, 12 lines in the 4.6-GHz and 14 lines in the 9.2 GHz spectra were resolved for N2OR. Eight copper lines at 2.7 GHz, about nine lines at 4.6 GHz and about six lines at 9.2 GHz were resolved for COX. Simulations of the EPR spectra were consistent with most of the resonances of the multiline spectra, including regions in the center of the spectra where overlap of the three seven-line patterns is proposed. These simulations indicated that Cu-Cu interaction, in a mixed-valence [Cu(1.5) ... Cu(1.5)], S = 1/2 site is consistent with, if not proof of, the unusual spectral features observed for N2OR and COX.

On the choice of orbitals for symmetry breaking problems with application to NO3

Abstract: The suitability of using approximate Brueckner determinants in coupled‐cluster (CC) studies of orbital symmetry‐breaking problems is explored. At least for the cases considered here [NO3(2A’2), N2(2Σg+) and NO2(2B2)], the Brueckner reference function, which by definition does not mix with single excitations in the CC wave function, preserves symmetry exactly. Furthermore, these solutions do not appear to be sensitive to the initial guess, as the same symmetric solutions are obtained starting with either symmetry‐broken or symmetry‐constrained initial guesses. The same behavior is not observed for Brueckner determinants obtained from configuration interaction calculations, where symmetry‐broken solutions are found. An evaluation of the merits of basing CC calculations on Brueckner determinants [B–CC] and quasirestricted Hartree–Fock [QRHF] reference functions (which also can be chosen to preserve symmetry exactly) is presented. Calculations carried out on the NO3 radical predict a C2v equilibrium geometry ...

Model-Based Object Tracking in Traffic Scenes

Abstract: This contribution addresses the problem of detection and tracking of moving vehicles in image sequences from traffic scenes recorded by a stationary camera. In order to exploit the a priori knowledge about the shape and the physical motion of vehicles in traffic scenes, a parameterized vehicle model is used for an intraframe matching process and a recursive estimator based on a motion model is used for motion estimation. The initial guess about the position and orientation for the models are computed with the help of a clustering approach of moving image features. Shadow edges of the models are taken into account in the matching process. This enables tracking of vehicles under complex illumination conditions and within a small effective field of view. Results on real world traffic scenes are presented and open problems are outlined.

The development of a functional digestive system in the African catfish, Clarias gariepinus (Burchell).

Abstract: The morphological and physiological development of the intestine, stomach, liver and pancreas of the African catfish, Clarius guriepinus (Burchell 1822), was investigated from hatching until 9 days after the start of exogenous feeding by histological, histochemical and immunohistochemical procedures. During the yolk sac period, lasting 48 hours at 30 C, the digestive system develops from a rather undifferentiated system into a distinct liver and pancreas and a segmented intestine (parts I to III). Insulin and glucagon producing cells were clearly found in the endocrine pancreatic islets from 14 hours after hatching onwards, while at the start of exogenous feeding, the exocrine pancreas showed an intense zymogen colouration. Exogenous feeding started three days after fertilization, i.e., 48 hours after hatching. At that moment, the rearing temperature was lowered to 27.5 C. The first day of feeding was referred to as day zero, changing into day 1 when the first 24 hours of feeding were completed. From the start of exogenous feeding onwards, aminopeptidase, non-specific esterase and ATP-ase were detected in the digestive system. Morphologically, the stomach was completed at day 4 of exogenous feeding. Gastric acid secretion started on day 4 and lead to a pH below 3.3 in the stomach on day 5. During the first four days of exogenous feeding, C-t-gastrin immunopositive cells were found throughout the gut, including the gastric epithelium. After day 4, the C-t-gastrin cells were only detected in the anterior intestine. The completeness of the stomach development was also marked by the appearance of non-specific esterase activity in the stomach epithelial cells on day 5. All data together clearly indicate that in Clarius gariepinus, the ontogeny of a functional digestive system has been completed on day 5 after the start of exogenous feeding, marking thereby the end of the larval period.

Derived amino acid sequences of the nosZ gene (respiratory N2O reductase) from Alcaligenes eutrophus, Pseudomonas aeruginosa and Pseudomonas stutzeri reveal potential copper-binding residues. Implications for the CuA site of N2O reductase and cytochrome-c oxidase.

Abstract: The nosZ genes encoding the multicopper enzyme nitrous oxide reductase of Alcaligenes eutrophus H16 and the type strain of Pseudomonas aeruginosa were cloned and sequenced for structural comparison of their gene products with the homologous product of the nosZ gene from Pseudomonas stutzeri [Viebrock, A. & Zumft, W. G. (1988) J. Bacteriol. 170, 4658–4668] and the subunit II of cytochrome-c oxidase (COII). Both types of enzymes possess the CuA binding site. The nosZ genes were identified in cosmid libraries by hybridization with an internal 1.22-kb PstI fragment (NS220) of nosZ from P. stutzeri. The derived amino acid sequences indicate unprocessed gene products of 70084 Da (A. eutrophus) and 70695 Da (P. aeruginosa). The N-terminal sequences of the NosZ proteins have the characteristics of signal peptides for transport. A homologous domain, extending over at least 50 residues, is shared among the three derived NosZ sequences and the CuA binding region of 32 COII sequences. Only three out of nine cysteine residues of the NosZ protein (P. stutzeri) are invariant. Cys618 and Cys622 are assigned to a binuclear center, A, which is thought to represent the CuA site of NosZ and is located close to the C terminus. Two conserved histidines, one methionine, one aspartate, one valine and two aromatic residues are also part of the CuA consensus sequence, which is the domain homologous between the two enzymes. The CuA consensus sequence, however, lacks four strictly conserved residues present in all COII sequences. Cys165 is likely to be a ligand of a second binuclear center, Z, for which we assume mainly histidine coordination. Of 23 histidine residues in NosZ (P. stutzeri), 14 are invariant, 7 of which are in regions with a degree of conservation well above the 50% positional identity between the Alcaligenes and Pseudomonas sequences. Conserved tryptophan residues are located close to several potential copper ligands. Trp615 may contribute to the observed quenching of fluorescence when the CuA site is occupied.

A versatile wave propagation model for the VHF/UHF range considering three-dimensional terrain

Abstract: A polarimetric wave propagation model for field strength forecasting and coverage prediction in the VHF/UHF frequency range is presented. The model uses a digital terrain data bank and considers multipath propagation. Based on the uniform geometrical theory of diffraction (UTD) and physical optics an approach is described for calculating the propagation effects in natural 3-D terrain, given by topological and morphographical data. The method for field strength forecasting is described and methods for the analysis of the predicted multipath signal are discussed. It is shown how the complex probability density function (PDF) for the receiver field strength and the field strength delay spectrum can be derived. Methods for further evaluation of the transmitting channel characteristics are discussed. >

Evidence from ultra-high-pressure marbles for recycling of sediments into the mantle

Abstract: ROCKS of crustal origin metamorphosed at ultra-high pressures (P>2.5 GPa) have been described from several orogenic belts1–5. In the western Alps, for example, ultra-high pressure rocks originally equilibrated at about 750 °C and 3.5 GPa (ref. 1). During decompression, these rocks were cooled considerably and therefore did not pass through the granulite stability field. Here we describe ultra-high-pressure metasediments that have equilibrated at higher temperatures (> 1,100 °C) and followed a different exhumation path. A calcsilicate marble from the Bohemian massif contains clinopyroxenes with potassium-rich feldspar exsolutions. Potassium contents in the original clinopyroxenes indicate crystallization at pressures above 3–4 GPa (refs 6, 7). The high peak pressures and temperatures inferred for this rock, and its association with high-temperature peridotites and high-pressure granulites, suggest that carbonate sediments were subducted into the upper mantle, equilibrated at mantle conditions and were then emplaced in the crust along with mantle rocks. Our observations thus support suggestions based on less direct evidence (such as mass-balance considerations in orogenic belts8, and ocean-island basalt geochemistry9,10) that a limited amount of sediment must be recycled into the mantle.

Building integrated software development environments. Part I: tool specification

Abstract: The conceptual modeling approach of the IPSEN (Integrated Project Support Environment) project for building highly integrated environments is based on using attributed graphs to model and implement arbitrary object structures, in particular all kinds of software documents and their relationships. A language based on graph grammars, called PROGRESS (PROgrammed Graph REwriting SyStems), and a suitable method for the application of this language, called graph grammar engineering, have been developed over the last ten years. This language and method are being extensively used for specifying the complex graph structures of internal document representations as well as for specifying the functionality of all tools (editors, browsers, analyzers, debuggers) working on these internal rpresentations. This paper explains the language and the method for applying the language based on a pragmatic nontrivial example of a software production process and its corresponding documents. In particular, it is shown why and how a graph grammar-based strongly typed language is perfectly suitable to formally specify highly integrated software tools. In addition, it is shown that the implementation of these tools (i.e., an environment composed of these tools) is systematically being derived from the formal specifications.

On workload characterization of relational database environments

Abstract: A relational database workload analyzer (REDWAR) is developed to characterize the workload in a DB2 environment. This is applied to study a production DB2 system where a structured query language (SQL) trace for a two-hour interval and an image copy of the database catalog were obtained. The results of the workload study are summarized. The structure and complexity of SQL statements, the makeup and run-time behavior of transactions/queries, and the composition of relations and views are discussed. The results obtained provide the important information needed to build a benchmark workload to evaluate the alternative design tradeoffs of database systems. >

Verification of a generalized Planck law for luminescence radiation from silicon solar cells

Abstract: A generalization of Planck's radiation law based on the principle of detailed balance predicts the emission of luminescence radiation from absorption data for direct transitions in semiconductors. Its validity for indirect transitions is questionable due to the participation of phonons. We have tested the validity for the indirect transitions in Si by measuring absolute values of the emission intensity from Si solar cells under forward bias at room temperature and find good agreement with theoretical predictions based on existing absorption data. The generalized Planck law, thus verified for the indirect transitions in Si, allows to determine the performance of solar cell materials from measuring the absolute intensity of their emission of luminescence radiation when irradiated by the sun.

A novel ozone sensor for direct eddy flux measurements

Abstract: A small, lightweight (1.5 kg) and fast-response ozone sensor for direct eddy flux measurements has been built. The basis for detection is the chemiluminescence of an organic dye adsorbed on dry silica gel in the reaction with ozone. The chemiluminescence is monitored with a cheap and small blue-sensitive photomultiplier. At a flow rate of 100 l min-1 the ozone sensor has a 90% response time of significantly better than 0.1 s with a detection limit lower than 50 ppt at S/N=3. There are no interferences from other atmospheric trace gases like NOx, H2O2 and PAN. Water vapour and SO2 enhance the chemiluminescence efficiency of the ozone sensor. Since their response times are 22 seconds and 30 minutes, respectively, no correlation between rapid ozone fluctuations and those of these two trace gases is noticed by the ozone sensor when operating at a frequency of 10 Hz.

Increase of the chlorophyll fluorescence ratio F690/F735 during the autumnal chlorophyll breakdown.

Abstract: The chlorophyll content and the fluorescence induction kinetics at two wavelengths (690 nm and 735 nm) have been measured in leaves of nine common broadleaf tree species during the autumnal chlorophyll breakdown. The ratio of the chlorophyll fluorescence maxima F690/F735 was determined at fluorescence maximum (fm) and at steady-state conditions (fs) by the laser-induced fluorescence emission using the two-wavelength fluorometer. The ratio F690/F735 increases with the leaf discolouring during the autumnal chlorophyll breakdown. The relationship between the chlorophyll content and the ratio F690/F735 can be expressed by a power function (curvilinear relationship) which is valid for all the species examined. In most cases the ratio F690/F735 measured in the upper leaf side is lower than that in the lower leaf side, but the trend is the same along the decreasing chlorophyll content. The ratio F690/F735 is always higher at maximum fluorescence than at steady-state fluorescence in the upper as well as lower leaf side and these values are well fitted in a linear correlation. This study confirms the usefulness of the ratio F690/F735 as a suitable non-destructive indicator of the in-vivo chlorophyll content, especially at medium and low chlorophyll content.