Showing papers by "Johannes Kepler University of Linz published in 1983"
TL;DR: In this paper, the temperature dependence of the impedance at frequencies between 100 Hz and 5 MHz and of the dc resistance of single perovskite in the temperature range between 300 and 1300 K were investigated.
Abstract: The temperature dependence of the impedance at frequencies between 100 Hz and 5 MHz and of the dc resistance of SrTiO3 and BaTiO3 single crystals are investigated in the temperature range between 300 and 1300 K. An anomalous behaviour of the capacitance can be explained phenom-enologically as due to the combined effects of bulk and surface properties. The analysis of the results yields strong evidence that the electric transport in this temperature range is mainly electronic, while ionic contributions play only a minor role. The results seem to be typical for oxidic perovskites and are expected to yield a better understanding of these systems, especially of their transport properties.
Die Temperaturabhangigkeit der Impedanz im Frequenzbereich zwischen 100 Hz und 5 MHz und des Gleichstromwiderstandes von SrTiO3- und BaTiO3-Einkristallen wird fur Temperaturen zwischen 300 und 1300 K untersucht. Ein anomales Verhalten der Kapazitat kann phanomeno-logisch durch kombinierte Einflusse von Volumen- und Grenzschichteigenschaften erklart werden. Die Analyse der Ergebnisse liefert starke Hinweise dafur, das der elektrische Transportmechanismus in diesem Temperaturbereich im wesentlichen elektronischer Natur ist und ionische Beitrage nur von untergeordneter Bedeutung sind. Die Ergebnisse scheinen beispielhaft fur alle oxidischen Perovskite zu sein und lassen ein besseres Verstandnis dieser Systeme, insbesondere ihrer Trans-porteigenschaften, erwarten.
128 citations
TL;DR: In a retrospective study, on a sample of 1021 patients with carcinoma of the lips, oral cavity and oropharynx, the clinically available factors at the time of the patient's first admission are analysed with reference to their prognostic relevance to create a prognostic index.
94 citations
23 May 1983
TL;DR: In this paper, it is shown how the critical-pair/completion approach can be extended to general rings and a set of reduction axioms is given, under which the correctness of the algorithm can be proven and which are preserved when passing from a ring R to the polynomial ring R[x1,...,,xn].
Abstract: In 1965, the author introduced a "critical-pair/completion" algorithm that starts from a finite set F of polynomials in K[x1,...,xn] (K a field) and produces a set G of polynomials such that the ideals generated by F and G are identical, but G is in a certain standard form (G is a "Grobner-basis"), for which a number of important decision and computability problems in polynomial ideal theory can be solved elegantly. In this paper, it is shown how the critical-pair/completion approach can be extended to general rings. One of the difficulties lies in the fact that, in general, the generators of an ideal in a ring do not naturally decompose into a "head" and a "rest" (left-hand side and right-hand side). Thus, the crucial notions of "reduction" and "critical pair" must be formulated in a new way that does not depend on any "rewrite" nature of the generators. The solution of this problem is the starting point of the paper. Furthermore, a set of reduction axioms is given, under which the correctness of the algorithm can be proven and which are preserved when passing from a ring R to the polynomial ring R[x1,...,,xn]. Z[x1,...,xn] is an important example of a ring in which the critical-pair/completion approach is possible.
83 citations
TL;DR: The two essential ideas of this algorithm are: the consideration of certain "critical pairs" associated with elements in E and the successive "completion" of E by adjoining the difference of normal forms of critical pairs.
Abstract: Given a finite set E of multivariate polynomials, the second author's 1965 algorithm constructs a set E' of polynomials such that E and E' generate the same ideal congruence, but E' has the additional property that the congruence can be decided by "reduction to normal forms w.r.t. E'." The two essential ideas of this algorithm are: the consideration of certain "critical pairs" associated with elements in E and the successive "completion" of E by adjoining the difference of normal forms of critical pairs.
80 citations
TL;DR: In this article, the influence of laser irradiance, substrate material and scanning velocity on deposition rate and widths of patterns has been investigated, and the lateral dimensions of the deposits can be as small as 1 μm.
Abstract: Polycrystalline Ni has been grown by decomposition of Ni(CO)4 using different wavelengths of the visible radiation of a Kr+ laser. The influence of laser irradiance, substrate material and scanning velocity on deposition rate and widths of patterns has been investigated. The deposition rates achieved are typically several μm/s, and the lateral dimensions of the deposits can be as small as 1 μm.
71 citations
TL;DR: In this article, the authors define two geometric concepts of a Banach space, property α and β, which generalize in a certain way the geometric situation of l andc o. They show that many Banach spaces may (3+e)-equivalently be renormed to have property α.
Abstract: We define two geometric concepts of a Banach space, property α and β, which generalize in a certain way the geometric situation ofl andc
o. These properties have been used by J. Lindenstrauss and J. Partington in the study of norm attaining operators. J. Partington has shown that every Banach space may (3+e)-equivalently be renormed to have property β. We show that many Banach spaces (e.g., every WCG space) may (3+e)-equivalently be renormed to have property α. However, an example due to S. Shelah shows that not every Banach space is isomorphic to a Banach space with property α.
65 citations
28 Mar 1983
TL;DR: In this paper, upper bounds for the degrees and the number of polynomials occuring in Grobner-bases of ideal polynomial ideals are given, and all the bounds are shown to be tight.
Abstract: In the bivariate case, upper bounds for the degrees and the number of polynomials occuring in Grobner-bases of polynomial ideals are given. In the case of the total degree ordering of monomials, the upper bound for the degrees is linear in the maximal degree of the polynomials in the given basis of the ideal. In the general case, the upper bound for the degrees is quadratic. The upper bound for the number of polynomials is linear in the minimal degree of the polynomials in the given basis. All the bounds are shown to be tight. The relevance of these bounds for constructive polynomial ideal theory is indicated.
59 citations
TL;DR: In this paper, the authors show that the evidence for a Stokes shift may be satisfactorily explained by a distribution of zero-phonon energies only, which suggests that the radiative states may be rigid.
Abstract: Many experimental data on the 1.4-eV photoluminescence of $a$-Si:H have been interpreted by the assumption of a Stokes shift of up to 0.5 eV. We show that the evidence for a Stokes shift may be satisfactorily explained by a distribution of zero-phonon energies only. This suggests that the radiative states may be rigid and so that there is no evidence for a significant disorder-induced electron-phonon interaction in the tail states of amorphous silicon.
55 citations
TL;DR: In this paper, a force field model constructed for the conformational analysis of polypyrrolic systems is reviewed and compared to experimental data where available for dipyr-rolic compounds such as pyrromethenes, dipyrromethanes, and pyrronethenones, for tripyrrins and for various verdinoid and rubinoid bile pigments.
54 citations
TL;DR: In this article, 60 adults from the city of Linz took part in an experiment where they read a story, The War of the Ghosts, in pairs, and were required to reproduce it either jointly, in dyads, or singly, and either immediately following or one week later.
Abstract: Sixty adults from the city of Linz took part in this experiment. They read a story—The War of the Ghosts—in pairs, and were required to reproduce it either jointly, in dyads, or singly, and either immediately following or one week later. In addition they were asked a number of specific questions about the story, and gave various ratings of confidence and completeness. As predicted, social (dyadic) performance increased confidence, completeness and the incidence of implicational errors (errors which do not contradict the original). Delay significantly diminished confidence. Analyses of confidence for right and wrong answers indicated that subjective testimonial validity was substantial in all conditions. Analyses of objective testimonial validity showed that dyads are more trustworthy than individuals when they are correct, but are less trustworthy when they happen to be wrong. They overall conjidence I accuracy correlation across conditions of +0.6 masks the fact that the greatest obstacle to valid testimony is inappropriate confidence in wrong answers, especially in dyads, and especially immediately after the event. The incidence of implicational errors was highly related positively to measures of confidence and accuracy, whereas confusional errors were independent. Implicational errors are regarded as an especially important element in schematic recall, and are an important aspect of the superiority of social performance.
50 citations
TL;DR: In this article, the redox behavior of LiClO4, NaClO 4, KClO2, RbClO3, RbCo2, CsClO 2, TiClO 3, BaCo2, Zn(CF3SO3) 2, ZnCo2 2, ClO 2 ·2 H2O, (Et4N)3 Fe(CN)6, (Bu4N),3 Fe
TL;DR: Reference cross sections, i.e., accurate cross sections obtained by averaging all the relevant published data points, are useful for practical applications and for comparison with theories as mentioned in this paper, and they can be calculated for one type of projectile by using the data from a large range of target atomic numbers, after normalizing the data by the Brandt-Lapicki theory.
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01 Feb 1983TL;DR: The dependence of the conductivity prefactor sigma 0 on the activation energy in a-Si:H has been determined by measuring the Staebler-Wronski effect.
Abstract: The dependence of the conductivity prefactor sigma 0 on the activation energy Ea in a-Si:H has been determined by measuring the Staebler-Wronski effect (1977, 1980) in undoped and n-doped glow discharge a-Si:H samples and by comparing DC conductivity measurements in differently n-doped samples in defined states. A very exact linear dependence of ln sigma 0 on Ea as described by the Meyer-Neldel rule is observed, with good quantitative agreement between the parameters for the two cases. On the basis of these results it is proposed that the Meyer-Neldel rule is fundamental in a-Si:H, by which it is meant that it has to be taken into account in any model for the electronic transport properties of this material, and that it should not be explained by a model specific to a-Si:H.
TL;DR: In this article, single crystal rods of silicon have been grown by laser-induced chemical vapor deposition (LCVD) using visible light and they were reported to be the first reported single crystals of any material grown by LCVD.
Abstract: Single crystal rods of silicon have been grown by laser-induced chemical vapor deposition (LCVD) using visible light. We believe these to be the first reported single crystals of any material grown by LCVD.
TL;DR: In this article, a computational method is used to estimate the uncertainties transmitted from this data base into results of thick-target PIXE analyses with reference to particular specimen types using beams of 2-3 MeV protons.
TL;DR: In this paper, the voltammetric behavior of several mono-and disaccharides has been investigated and the properties of the electrodes were studied in a stationary system, in a flow-injection system and in combination with high-performance liquid chromatography.
Abstract: In order to develop new sensitive detectors for the determination of sugars after HPLC-separation, the voltammetric behaviour of several mono- and disaccharides has been investigated. Nickel electrodes turned out to be well suited for this problem. The properties of the electrodes were studied in a stationary system, in a flow-injection system and in combination with high-performance liquid chromatography. Parameters for optimisation are discussed and the application to the detection of several sugars is shown.
TL;DR: The globally convergent algorithm, well-established for the solution of nonlinear equations is extended to restricted optimization problems, and the hypotheses for the convergence of the algorithm may be secured for the class of convex problems.
Abstract: The continuation method, well-established for the solution of nonlinear equations is extended to restricted optimization problems. Only the locally active restrictions are considered along the homotopy path. It is assumed that there are only finitely many critical points, i. e. that there are only finitely many changes of the index set of active restrictions. The globally convergent algorithm which we present proceeds in three stages:
For the class of convex problems, the hypotheses for the convergence of the algorithm may be secured. The algorithm is applied to several examples.
TL;DR: In this article, a set of model compounds substituted with methyl groups in positions 7,8,12 and 13 were prepared to elucidate the tautomerism within the pyrromethene moiety of unsymmetrical bilatrienes and of 2,3-dihydrobilatrienen-abc.
Abstract: A set of model compounds substituted with methyl groups in positions 7,8,12 and 13 were prepared to elucidate the tautomerism within the pyrromethene moiety of unsymmetrical bilatrienes and of 2,3-dihydrobilatrienes-abc. Configurational and 1H-NMR signal assignments were achieved using NOE difference spectra, coupling phenomena and comparison to the spectra of compounds substituted with ethyl groups in strategic positions. By application of resolution enhancement and the COSY-technique a characteristic coupling pattern between the methyl groups of a pyrrole ring which is different from the one observed for the pyrrolenin ring could be documented using derivatives with fixed tautomeric structure (N-methylation). All unsymmetrical bilatrienes and 2,3-dihydrobilatrienes-abc investigated are shown to be single tautomers — the position of the proton (N22, N23) obviously is governed by an optimisation of intramolecular hydrogen bonding.
01 Jan 1983
TL;DR: In contrast to this standard CVD technique, laser-induced chemical vapor deposition (LCVD) allows local deposition of materials within the focus of a laser as discussed by the authors, and thus it may become an alternative method in cases where at present material patterns are produced by conventional CVD techniques and photolithographic methods.
Abstract: Chemical vapor deposition (CVD) is a widely used technique for the production of thin films of metals, semiconductors, and insulators [1]. In the standard procedure the chemical reaction is thermally activated near or on the hot surface of the substrate, where deposition takes place. Normally, the substrate is directly and uniformly heated and one obtains an extended uniform film of the deposited material. In contrast to this standard CVD technique, laser-induced chemical vapor deposition (LCVD) allows local deposition of materials within the focus of a laser. Therefore, LCVD may become an alternative method in cases where at present material patterns are produced by standard CVD techniques and photolithographic methods.. While the production of microstructures according to these standard techniques requires several different steps, LCVD allows one-step deposition or direct writing of structures with lateral dimensions down to at least 1 µm. Because of the high deposition rates achieved in pyrolytic LCVD, the production of three-dimensional structures of micron size is also possible.
TL;DR: In this article, the crystal structure of (Z,Z, Z)-19, 24-dihydro-1-methoxy-19-oxo-2,7,13,18-tetramethyl-3,8,12, 17tetraethyl-22H-bilin was determined at 101 K by X-ray diffraction methods: space group PĪ, a = 9.532(2), b = 12.189(4), c = 13.984(4)A, α = 114.
TL;DR: Using fixed tautomeric structures of 3,4-dihydropyrromethenones and 2,3-Dihydrobilatrienes-abc (N- and O-alkylation) a prevalence of the lactam and bis-lactam form over lactimes by several orders of magnitude could be deduced as discussed by the authors.
Abstract: Using fixed tautomeric structures of 3,4-dihydropyrromethenones and 2,3-dihydrobilatrienes-abc (N- and O-alkylation) a prevalence of the lactam and bis-lactam form over lactimes by several orders of magnitude could be deduced. Although there are complications arising from side reactions of the pyrrolidinone fragment, protonation equilibria provided valuable clues for this result which is nicely complemented by NMR-, IR and UV-VIS data.
TL;DR: In this article, the suitability of local temperature measurements by cw Raman spectroscopy for the CH4/H2 CVD system has been established and the temperature profiles in a model reactor were derived from H2 pure rotational lines and from hot bands of thev1 vibrational band of CH4.
Abstract: The suitability of local temperature measurements by cw Raman spectroscopy for the CH4/H2 CVD system has been established. The temperature profiles in a model reactor were derived from H2 pure rotational lines and from hot bands of thev1 vibrational band of CH4. Experimental results are presented for substrate temperatures of 773 K and of 1473 K. High accuracy of measurement and excellent agreement with theoretical solutions for the temperature field within the reactor were found.
TL;DR: In this article, a simple high resolution charge sensitive preamplifier for surface barrier detectors (SBD) is described which uses drain feedback for charge restoration, and it is shown that electronic noise can be reduced from 5 keV to 0.5 keV if one cools the SBD to 77 K and the field effect transistor (FET) to about 100 K.
TL;DR: The spectroscopic properties of the various diastereomers of five compounds were recorded and are discussed with respect to their utility in structural studies of the natural pigment system as mentioned in this paper, however, they could only be prepared for thermodynamic reasons.
Abstract: 2,3-Dihydrobilatrienes-abc substituted analogous to the natural chromophor of phytochrome may exhibit diastereomerism at the exocyclic double bond of the unsaturated lactam ring. Their properties are comparable to the previouslystudied bilatriene-abc diastereomers. At the exocyclic double bond of the saturated lactam ring however, diastereomers could only be prepared for thermodynamic reasons. The spectroscopic properties of the various diastereomers of five compounds were recorded and are discussed with respect to their utility in structural studies of the natural pigment system.
TL;DR: In this article, a renormalized field theory applied to the model of Siggia and Nelson is used to explain the observable critical and precritical temperature dependence of the mass diffusion, thermal conductivity, and dynamic structure factor of helium mixtures.
Abstract: The critical dynamics of the $\ensuremath{\lambda}$ transition in $^{3}\mathrm{He}$-$^{4}\mathrm{He}$ mixtures are studied by means of renormalized field theory applied to the model of Siggia and Nelson. A diagonal representation for the equations of motion is introduced, which greatly simplifies the computations in two-loop order. A universal connection is found with the asymptotic critical dynamics of pure $^{4}\mathrm{He}$ in all orders of perturbation theory. The observable critical dynamics of helium mixtures are dominated by nonuniversal crossover effects which can be properly described only within a nonlinear renormalization-group approach. The theory is applied to explain the observable critical and precritical temperature dependence of the mass diffusion $D$, of the thermal conductivity $\ensuremath{\kappa}$, of the thermal diffusion ratio ${k}_{T}$, and of the dynamic structure factor for $T\ensuremath{\ge}{T}_{\ensuremath{\lambda}}(X)$. Recent experimental data for the transport coefficients at the molar $^{3}\mathrm{He}$ concentration $X=0.05$ by Gestrich and Meyer are used to identify the nonuniversal parameters of the theory in the range $X\ensuremath{\ll}1$. Consistency with the dynamics of pure $^{4}\mathrm{He}$ ($X=0$) is verified. Predictions without adjustable parameters are made for the dynamic structure factor and the transport coefficients in very dilute mixtures. The Siggia-Kawasaki problem concerning the leading $X$ dependence of $\ensuremath{\kappa}({T}_{\ensuremath{\lambda}})$ in the $X\ensuremath{\rightarrow}0$ limit is resolved. It is demonstrated that Siggia's prediction $\ensuremath{\kappa}({T}_{\ensuremath{\lambda}})\ensuremath{\sim}{X}^{\ensuremath{-}1}$ is correct but not observable. Theoretical extrapolations to $Xg0.05$ without adjustable parameters are presented and compared with measured transport coefficients at $X=0.11 \mathrm{and} 0.15$. The overall agreement is satisfactory. Deviations of order 15% exist with the thermal conductivity $\ensuremath{\kappa}$ at $X=0.15$. This may be attributed to dynamic effects arising from the singular specific heat and mass susceptibility, which are not included in the present analysis.
01 Jan 1983
TL;DR: This chapter is devoted to the arithmetic Operations, essentially addition, multiplication, exponentiation, division, gcd calculation and evaluation, on the basic algebraic domains.
Abstract: This chapter is devoted to the arithmetic Operations, essentially addition, multiplication, exponentiation, division, gcd calculation and evaluation, on the basic algebraic domains. The algorithms for these basic domains are those most frequently used in any Computer algebra system. Therefore the best known algorithms, from a computational point of view, are presented. The basic domains considered here are the rational integers, the rational numbers, integers modulo m, Gaussian integers, polynomials, rational functions, power series, finite fields and P-adic numbers. Bounds on the maximum, minimum and average Computing time (t +, t -, t*) for the various algorithms are given.
TL;DR: In this paper, 3,4-Dihydropyrromethenones and 2,3-dihydrobilatrienes-abc are deprotonated with a characteristicpKa value of about 11-12 at the NH of the saturated lactam ring.
Abstract: 3,4-Dihydropyrromethenones and 2,3-dihydrobilatrienes-abc are deprotonated with a characteristicpKa value of about 11–12 at the NH of the saturated lactam ring. This deprotonation step depends on the availability of stabilisation by hydrogen bonding and charge delocalisation. This was deduced bypKa measurements of 20 derivates bearing methyl groups at certain N-positions to block deprotonation selectively. Moreover, a1H-NMR shift criterion was established to detect the deprotonation site. Fluorescence data are given for several 2,3-dihydrobilatrienes-abc; a crossover of relative acidity and basicity in the excited state was observed in the case of a “normal” 2,3-dihydrobilatriene-abc by applying aForster cycle.
TL;DR: In this paper, the authors used a monolithic Laue triple crystal arrangement and prism deflection between the crystal plates for the observation of the Fraunhofer diffraction at 5 mm and 2.5 mm wide slits.
Abstract: Triple Laue-rocking curves show a very narrow central peak whose half width is in the order of 0.001 sec of arc. This phenomena has been calculated numerically and analytically. The experiments have been done using a monolithic Laue triple crystal arrangement and prism deflection between the crystal plates. The high angular resolution has been used for the observation of the Fraunhofer diffraction at 5 mm and 2.5 mm wide slits. The applicability of this technique to other investigations in the fields of neutron-matter and neutron-field interactions is discussed.
TL;DR: Fuzzy-valued fuzzy measures are defined in an axiomatic way and shown that they can be characterized by a suitable family of ordinary measures and Markov kernels.