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  • Springer  (61.397)
  • Institute of Physics  (11.196)
  • 1990-1994  (72.593)
  • 1970-1974
  • 1950-1954
  • 1991  (72.593)
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  • 1990-1994  (72.593)
  • 1970-1974
  • 1950-1954
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  • 101
    Digitale Medien
    Digitale Medien
    A general study of maximal robust stability regions (1991)
    Springer
    Circuits, systems and signal processing 10 (1991), S. 15-30 
    Details
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract In the study of robust stability, the largest coefficient region of a given stable polynomial that guarantees stability preservation under perturbation of coefficients is to be determined. A general consideration including both Hurwitz and Schur polynomials is treated in this paper. For this purpose, the notion ofperturbation constant is introduced. As a consequence of our results, we also introduce a general Kharitonov-type stability test which is based on testing the stability and perturbation constant of a single polynomial.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01183238
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  • 102
    Digitale Medien
    Digitale Medien
    CAS-CAS transform for 2-D signals: A few applications (1991)
    Springer
    Circuits, systems and signal processing 10 (1991), S. 163-173 
    Details
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract A few applications of a separable Hartley-like (CAS-CAS) transform in two-dimensional (2-D) signal processing is presented. The applications discussed include (i) the interpolation of signals, (ii) the computation of Hilbert transform, and (iii) the complex cepstrum computation. The computational advantage of the proposed methods over the algorithms using 2-D FFT are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01183769
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  • 103
    Digitale Medien
    Digitale Medien
    Efficient method for computing double matrix products (1991)
    Springer
    Circuits, systems and signal processing 10 (1991), S. 221-232 
    Details
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract We introduce an efficient method for computing matrix products of the formY=AXB, whereA andB are sparse and constant. We analyze the complexity of the method, develop quantitative criteria for determining when it can be used effectively, and demonstrate its use in a Kalman filter.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01183772
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  • 104
    Digitale Medien
    Digitale Medien
    Symmetric sine and cosine structures for trigonometric transforms (1991)
    Springer
    Circuits, systems and signal processing 10 (1991), S. 433-441 
    Details
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract In this paper we firstly define two new formulations, the symmetric sine structure (SSS) and the symmetric cosine structure (SCS). Then we propose a simple algorithm to realize one-dimensional SCS and SSS with sequence lengths equal to 2 m . We show that a 2m-length discrete Hartley transform can be realized through a 2 m−1-length SCS and a 2 m−1-length SSS, which achieves the same multiplicative complexity as the minimum number of multiplications reported in the literature. However, our approach gives the advantage of requiring less additions compared with conventional approaches. Furthermore, this approach can also be applied to realize a 2m-length real-valued discrete Fourier transform, which requires the lowest number of multiplications compared with conventional real-valued algorithms and needs no complex number operations as found in other real-valued algorithms.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01194881
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  • 105
    Digitale Medien
    Digitale Medien
    Sign algorithms for blind equalization and their convergence analysis (1991)
    Springer
    Circuits, systems and signal processing 10 (1991), S. 393-431 
    Details
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract In blind equalization a communication channel is adaptively equalized without resorting to the usual training sequence. In this paper we have introduced two new algorithms for blind equalization, which hard limit the equalizer input or the error at the output of the equalizer. These new algorithms are simple to implement and reduce the number of multiplications by approximately one-half. We show by way of simulations that the performance of the algorithm resulting from hardlimiting the error is comparable with the performance of the corresponding algorithm in which the error is not hardlimited. We formulate the new sign-error algorithm as a stochastic minimization of an error functional and demonstrate that the case of zero intersymbol interference corresponds to local minima of this error functional. We also present convergence analysis to predict the output mean square error in both these sign algorithms. Since the algorithms are highly nonlinear we incorporate several simplifying approximations and provide heuristic justifications for the validity of these approximations when the algorithms are operated in a typical practical environment. Computer simulations demonstrate the accuracy of the predicted convergence behavior.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01194880
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  • 106
    Digitale Medien
    Digitale Medien
    Robust stability and sensitivity of input-output systems over extended spaces (1991)
    Springer
    Circuits, systems and signal processing 10 (1991), S. 443-454 
    Details
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract This paper is the second part of [6] which is concerned with the sensitivity of general input-output systems over extended spaces. It is assumed that such systems, which need not be of feedback type, are governed by nonlinear operator equations relating the input, the state, and the output. These equations depend on a parameterA that can vary in a neighborhood of a nominal valueA 0. Essentially, a system is called insensitive if any truncation of its output depends continuously onA provided the input is fixed. The theorems derived provide sufficient conditions for insensitivity. A control system of a feedback-feedforward type and a dynamical system described by a linear vector differential equation on [0, ∞) are discussed as examples.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01194882
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  • 107
    Digitale Medien
    Digitale Medien
    On rational interpolation with positivity constraints (1991)
    Springer
    Circuits, systems and signal processing 10 (1991), S. 471-483 
    Details
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract The problem of interpolating a given set of points by means of a squared magnitude rational function of minimal degree is considered. In this way, the resulting interpolating function can be factorized to yield a stable and minimum-phase transference. It is shown that in the polynomial case a nonnegative solution is easily obtained by adding to the standard Hermite interpolation polynomial a suitable term of immediately higher degree. Concerning the general rational case, a computationally efficient procedure, based on a Hermite-type parametrization, is suggested. The positivity requirement may again be met by inserting suitable terms in the numerator and denominator polynomials. An example is worked out to show the practicality of the method.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01194884
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  • 108
    Digitale Medien
    Digitale Medien
    Index forThe Geneva Papers on Risk and Insurance, 1976 Through 1989 (1991)
    Springer
    The Geneva risk and insurance review 16 (1991), S. 75-102 
    Details
    ISSN: 1554-9658
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Wirtschaftswissenschaften
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00942858
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  • 109
    Digitale Medien
    Digitale Medien
    Reliability of risk management: Market insurance, self-insurance and self-protection reconsidered (1991)
    Springer
    The Geneva risk and insurance review 16 (1991), S. 45-58 
    Details
    ISSN: 1554-9658
    Schlagwort(e): Default Risk ; Reliability ; Risk Aversion ; Risk Management
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Wirtschaftswissenschaften
    Notizen: Abstract This paper examines the three main tools of risk management in a setting where reliability cannot be guaranteed. Thus, for example, insurers might be insolvent, sprinkler systems might be inoperative and alarm systems might be faulty. These types of nonreliability are shown to have significant consequences for risk management. In particular, the relationships between increased risk aversion and the use of the various risk management tools do not carry over from models with full reliability. Moreover, the well-known result of Ehrlich and Becker, that market insurance and selfinsurance are substitutes, is shown to fail in the presence of nonreliability risk.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00942856
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  • 110
    Digitale Medien
    Digitale Medien
    Multivariate risk aversion and uninsurable risks: Theory and applications (1991)
    Springer
    The Geneva risk and insurance review 16 (1991), S. 7-43 
    Details
    ISSN: 1554-9658
    Schlagwort(e): Multivariate Risk Aversion ; Uninsurable Risks ; Global Interpersonal Comparisons of Attitudes Towards Risk ; Multivariate Risk-Sharing ; Expected Utility ; Non-Expected Utility
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Wirtschaftswissenschaften
    Notizen: Abstract The objective of this paper is to develop conditions for global multivariate comparative risk aversion in the presence of uninsurable, or background, risks, and thus generalize Kihlstrom and Mirman [1974] and Karni [1979,1989]. We analyze von Neumann-Morgenstern (VNM) utility functionsas well as smooth preference functionals which are nonlinear in distribution but locally linear in probabilities. In each case we provide an economic application which illustrates how our theorems can be used. We analyze a risk sharing, a portfolio choice, and a labor supply problem for VNM utility functions, and the optimal allocation of effort to risky technologies in the presence of a random supply (or quality) of a public good for nonlinear preference functionals. We consider thecase where the random variables are mean-independent as well as the case where they are independent. In the labor supply application for VNM utility functions, we show that if the two risks are independent, the comparative statics effect of greater risk aversion on labor supply in the presence of a background non-wage income risk is determined by a monotonic relationship between labor supply and the wage rate under certainty. That is, we extend the applicability of the Diamond-Stiglitz [1974]-Kihlstrom-Mirman [1974]single-crossing property to the case where an independent background risk is present.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00942855
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  • 111
    Digitale Medien
    Digitale Medien
    Social insurance (1991)
    Springer
    The Geneva risk and insurance review 16 (1991), S. 113-131 
    Details
    ISSN: 1554-9658
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Wirtschaftswissenschaften
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02386300
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  • 112
    Digitale Medien
    Digitale Medien
    Social insurance and social security: A comment on Professor Atkinson's lecture (1991)
    Springer
    The Geneva risk and insurance review 16 (1991), S. 133-135 
    Details
    ISSN: 1554-9658
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Wirtschaftswissenschaften
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02386301
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  • 113
    Digitale Medien
    Digitale Medien
    Review article of Von Furstenberg'sActing under Uncertainty: Multidisciplinary Conceptions (1991)
    Springer
    The Geneva risk and insurance review 16 (1991), S. 201-203 
    Details
    ISSN: 1554-9658
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Wirtschaftswissenschaften
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02386307
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  • 114
    Digitale Medien
    Digitale Medien
    International P/L insurance output, input, and productivity comparisons (1991)
    Springer
    The Geneva risk and insurance review 16 (1991), S. 179-200 
    Details
    ISSN: 1554-9658
    Schlagwort(e): Divisia Index ; Productivity ; Insurance ; Translog
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Wirtschaftswissenschaften
    Notizen: Abstract This research provides (bilateral) divisia and multilateral divisia indexes of output, input, and productivity for the property-liability (P-L) insurance industry for the following countries: United States, West Germany, Switzerland, France, and Japan. The time period studied is 1975 to 1987. The results indicate that considerable diversity exists among different countries, with Japan showing the weakest productivity growth. The United States and West Germany are associated overall with high productivity.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02386306
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  • 115
    Digitale Medien
    Digitale Medien
    A nonchromatographic assay for sorbitol in chemically complex growth media containing sorbose (1991)
    Springer
    Journal of industrial microbiology and biotechnology 7 (1991), S. 57-61 
    Details
    ISSN: 1476-5535
    Schlagwort(e): Gluconobacter oxydans ; Sorbitol assay ; Sugar alcohols ; Lowry-Lopez interference assay
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Summary Microbiologists who lack gas-chromatographic equipment cannot easily study the microbial conversion of sorbitol to sorbose, because there is no other proven method for quantitatively measuring sorbitol in complex growth media. The purpose of this study was to determine if the polyol assay suggested by Mäkinen in 1980 could be used to measure sorbitol depletion in chemically complex bacteriological-culture media containing sorbose. After we pretreated the culture medium to remove interfering phosphate complexes and slightly modified Mäkinen's assay, we were able to detect 0.1 mg/ml differences in sorbitol concentrations that varied between 0.9 and 1.5 mg of sorbitol/ml. The presence of sorbose in the complex medium did not affect the assay. Growing cultures ofGluconobacter oxydans were used to test this assay, because these bacteria reportedly oxidize sorbitol to sorbose and quantitatively release the sorbose into the growth medium. When samples of the culture medium removed during growth were centrifuged to remove cells and precipitated to remove interfering substances then tested with the mofidied Mäkinen assay, these cultures showed a sorbitol depletion rate of 4.9 (±0.1) mg/ml h−1. The Fehling's assay on the same cultures showed a sorbose accumulation rate of 5.12 (±0.01) mg/ml h−1. We concluded that the modified Mäkinen phosphate-interference assay can be satisfactorily used to quantitatively screen cultures for their ability to oxidize sorbitol.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01575604
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  • 116
    Digitale Medien
    Digitale Medien
    Citric acid production from beet molasses by cell recycle ofAspergillus niger (1991)
    Springer
    Journal of industrial microbiology and biotechnology 7 (1991), S. 71-73 
    Details
    ISSN: 1476-5535
    Schlagwort(e): Citric acid ; Surface fermentation ; Substrate pH
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Summary Production of citric acid from beet molasses at a varying pH profile using cell recycle ofAspergillus niger was investigated. Best results in terms of citric acid concentration, yield, productivity and specific citric acid productivity were obtained with a substrate pH of 3.0.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01575606
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  • 117
    Digitale Medien
    Digitale Medien
    Announcement (1991)
    Springer
    Journal of industrial microbiology and biotechnology 7 (1991), S. 75-75 
    Details
    ISSN: 1476-5535
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01575607
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  • 118
    Digitale Medien
    Digitale Medien
    Expression of polyketide biosynthesis and regulatory genes in heterologous streptomycetes (1991)
    Springer
    Journal of industrial microbiology and biotechnology 7 (1991), S. 163-174 
    Details
    ISSN: 1476-5535
    Schlagwort(e): Hybrid antibiotics ; Polyketide biosynthesis ; Anthracyclines ; Actinorhodin ; Streptomycetes ; Interspecies gene cloning
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Summary There are now several examples showing that hybrid secondary metabolites can be produced as a result of interspecies cloning of antibiotic biosynthesis genes in streptomycetes. This paper reviews examples of hybrid secondary metabolite production, and examines the underlying biochemical and regulatory principles leading to the formation of hybrid anthraquinones by recombinant anthracycline-producing streptomycetes carrying actinorhodin biosynthesis genes. An anthraquinone, aloesaponarin II, was produced by cloning theactI, actIII, actIV, andactVII genes (pANT12) of actinorhodin biosynthesis pathway fromStreptomyces coelicolor in anthracycline producing streptomycetes.Streptomyces galilaeus strains 31 133 and 31 671, aclacinomycin and 2-hydroxyaklavinone producers, respectively, formed aloesaponarin II as their major polyketide product when transformed with pANT12. Subcloning experiments indicated that a 2.8-kbXhoI fragment containing only theactI andactVII loci was necessary for aloesaponarin II biosynthesis byS. galilaeus 31 133. WhenS. galilaeus 31 671 was transformed with theactI, actVII, andactIV genes, however, the recombinant strain produced two novel anthraquinones, desoxyerythrolaccin and 1-0-methyldesoxyerythrolaccin. WhenS. galilaeus 31671 was transformed with only the intactactIII gene (pANT45), aklavinone was formed exclusively. These experiments indicate a function for theactIII gene, which is the reduction of the keto group at C-9 from the carboxyl terminus of the assembled polyketide to the corresponding secondary alcohol. The effects of three regulatory loci,dauG, dnrR1, andasaA, on the production of natural and hybrid polyketides were also shown.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01575879
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  • 119
    Digitale Medien
    Digitale Medien
    The involvement of trehalose in yeast stress tolerance (1991)
    Springer
    Journal of industrial microbiology and biotechnology 7 (1991), S. 191-195 
    Details
    ISSN: 1476-5535
    Schlagwort(e): Yeast ; Trehalose ; Osmotolerance ; Viability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Summary A total of 12 yeast strains from various genera were examined for their ability to produce ethanol in the presence of high concentrations of glucose. From these studies, the yeastsTorulaspora delbrueckii andZygosaccharomyces rouxii were observed to the most osmotolerant. These osmotolerant yeast strains were also observed to possess high concentrations of intracellular trehalose. Futhermore, these strains were found to be tolerant to long-term storage at −20°C and to storage at 4°C in beer containing 5% (v/v) ethanol. Cells containing high trehalose levels at the time of freezing or cold storage exhibited the highest cell viabilities. Trehalose concentration was observed to increase during growth on glucose, reaching a maximum after 24–48 h. Increasing the incubation temperature from 21 to 40°C also resulted in an increase in intracellular trehalose content. These results suggest that trehalose plays a role in enhancing yeast survival under environmentally stressful conditions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01575882
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  • 120
    Digitale Medien
    Digitale Medien
    High-level secretion of biologically active aprotinin from the yeastPichia pastoris (1991)
    Springer
    Journal of industrial microbiology and biotechnology 7 (1991), S. 197-201 
    Details
    ISSN: 1476-5535
    Schlagwort(e): Secretion ; Proteolytic processing ; Protease inhibitor ; Pichia ; Yeast expression ; Aprotinin
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Summary A synthetic gene encoding aprotinin (bovine pancreatic trypsin, inhibitor) was fused to theSaccharomyces cerevisiae prepro alpha mating factor leader sequence at the dibasic amino acid processing site.Pichia pastoris strains were developed to'express one or multiple copies of a methanol-inducible expression cassette containing the gene fusion.P. pastoris containing a single copy of the vector secreed approximately 150 mg/l of immunoreactive protein. A construct bearing five copies of the expression cassette secreted 930 mg/l of aprotinin. The purified aprotinin molecule was equipoten with the native molecule in a trypsin inhibition assay. Protein sequence analysis showed that the alpha factor-aprotinin fusion was not processed at the basic amino acid residues Lys-Arg. Instead, recombinant aprotinin had additional N-terminal amino acids derived from prepro alpha factor. The N-terminal extension was variably 11 or 4 amino acids. Inclusion of the spacer DNA sequence encoding Glu and Ala between aprotinin and the Lys-Arg processing site led to the secretion of a biologically active aprotinin containing only a Glu-Ala N-terminal extension.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01575883
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  • 121
    Digitale Medien
    Digitale Medien
    Automatic whole broth multi-fermentor sampling (1991)
    Springer
    Journal of industrial microbiology and biotechnology 7 (1991), S. 215-220 
    Details
    ISSN: 1476-5535
    Schlagwort(e): Fermentation monitoring ; Automatic sampling ; Aseptic sampling
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Summary An efficient, aseptic method of obtaining whole broth fermentation samples was developed based on a piston-valve, a local sample loop, and an ability to drive the entire sample volume with sterile air through a sample line and into a remote tube. The configuration delivers 10-ml samples 10 m away with about 4 ml of broth wasted in the sampling process. An autosampler was enhanced and programmed to control acquisition into chilled tubes. The autosampler-based system represents a convenient way to provide frequent samples to profile intracellular and extracellular components for yeast and bacterial fermentations. A configuration to provide sampling from six fermentors with a multi-rack autosampler will be presented.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01575886
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  • 122
    Digitale Medien
    Digitale Medien
    Biological activity of a transforming growth factor-alpha-Pseudomonas exotoxin fusion protein in vitro and in vivo (1991)
    Springer
    Journal of industrial microbiology and biotechnology 7 (1991), S. 203-207 
    Details
    ISSN: 1476-5535
    Schlagwort(e): Epidermal growth factor ; Exotoxin ; Cancer
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Summary Transforming growth factor-alpha (TGFα)-pseudomonas exotoxin-40 (PE40) is a chimeric protein consisting of an N-terminal TGFα domain fused to a C-terminal 40-kDa segment of the pseudomonas exotoxin A protein. TGFα-PE40 exhibits the receptor binding activity of TGFα and the cell killing activity of PE40. In the current study, we report that a modified TGFα-PE40 derivative significantly prolongs the survival of nude mice bearing tumors derived from cell lines which express the epidermal growth factor receptor (EGFR). In addition, the therapeutic benefit of this protein is mediated by specific binding to the EGF receptor. These results indicate that a therapeutic window exists in vivo for the use of some growth factor-toxin fusion proteins as anticancer agents.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01575884
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  • 123
    Digitale Medien
    Digitale Medien
    Beijerinckia indica var.penicillanicum penicillin V acylase: enhanced enzyme production by catabolite repression-resistant mutant and effect of solvents on enzyme activity (1991)
    Springer
    Journal of industrial microbiology and biotechnology 7 (1991), S. 209-214 
    Details
    ISSN: 1476-5535
    Schlagwort(e): Penicillin V acylase ; Beijerinckia indica var.penicillanicum ; Mutation ; Solvent effect
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Summary Beijerinckia indica var.penicillanicum mutant UREMS-5, producing 168% more penicillin V acylase, was obtained by successive treatment with UV, γ-irradiation and ethylmethane sulfonate. Penicillin V acylase production by the mutant strain was resistant to catabolite repression by glucose. Incorporation of glucose, sodium glutamate and vegetable oils in the medium enhanced enzyme production. The maximum specific production of penicillin V acylase was 244 IU/g dry weight of cells. Effect of solvents on hydrolysis of penicillin V by soluble penicillin V acylase and whole cells was studied. Methylene chloride, chloroform and carbon tetrachloride significantly stimulated the rate of penicillin V hydrolysis by whole cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01575885
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  • 124
    Digitale Medien
    Digitale Medien
    Society for Industrial Microbiology (1991)
    Springer
    Journal of industrial microbiology and biotechnology 7 (1991), S. 227-228 
    Details
    ISSN: 1476-5535
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01575888
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  • 125
    Digitale Medien
    Digitale Medien
    Influence of impeller speed on citric acid production and selected enzyme activities of the TCA cycle (1991)
    Springer
    Journal of industrial microbiology and biotechnology 7 (1991), S. 221-225 
    Details
    ISSN: 1476-5535
    Schlagwort(e): Citric acid ; Aspergillus niger ; Submerged culture ; Stirred tank fermenter
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Summary The effect of impeller speed on citric acid production and selected enzyme activities of the TCA cycle was studied. The highest yield of citric acid (28 g/l) was obtained in culture agitated at lower speed (300 rpm). The activity of citrate synthase decreased with the increase of speed of agitation, while the activity of aconitase and isocitrate dehydrogenase increased with the increase in agitation speed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01575887
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  • 126
    Digitale Medien
    Digitale Medien
    Transposition and transduction of plasmid DNA inStreptomyces spp. (1991)
    Springer
    Journal of industrial microbiology and biotechnology 7 (1991), S. 229-234 
    Details
    ISSN: 1476-5535
    Schlagwort(e): Bacteriophage FP43 ; Tn5096 ; Tn5099 ; IS493 ; Streptomycete
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Summary To expand the application of molecular genetics to many different streptomycete species, we have been developing two potentially widely applicable methodologies: transposon mutagenesis and plasmid transduction. We constructed three transposons from theStreptomyces lividans insertion sequence IS493. Tn5096 and Tn5097 contain an apramycin resistance gene inserted in different orientations between the two open reading frames of IS493. These transposons transpose from different plasmids into many different sites in theStreptomyces griseofuscus chromosome and into its resident linear plasmids. Tn5099 contains a promoterlessxylE gene and a hygromycin-resistance gene inserted in IS493 close to one end. Tn5099 transposes inS. griseofuscus giving operon fusions in some cases that drive expression of thexylE gene product, catechol deoxygenase, giving yellow colonies in the presence of catechol. We have also developed plasmid vectors that can be transduced into many streptomycete species by bacteriophage FP43. We describe the characterization of FP43 and mapping of several bacteriophage functions. The region of cloned FP43 DNA essential for plasmid transduction includes the origin for headful packaging.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01577649
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  • 127
    Digitale Medien
    Digitale Medien
    Chloroperoxidase, a peroxidase with potential (1991)
    Springer
    Journal of industrial microbiology and biotechnology 7 (1991), S. 235-241 
    Details
    ISSN: 1476-5535
    Schlagwort(e): Chloroperoxidase ; Enzyme purification ; Enzyme immobilization
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Summary Chloroperoxidase is an extracellular heme glycoprotein produced by the imperfect fungusCaldariomyces fumago. The enzyme can catalyse chlorination reactions as well as act as a catalase or a peroxidase. As a peroxidase, it has a wide substrate specificity and we are interested in some applied aspects of this activity, requiring the production and purification of moderate quantities of the enzyme. High levels of chloroperoxidase are produced in a fructose synthetic medium, and highest enzyme production occurs in a low-shear environment. fungal pellets produce enzyme continuously at low medium replacement rates and at up to 0.6 g enzyme per 1: chloroperoxidase is essentially the only extracellular enzyme produced. Enzyme purification is uncomplicated and gives good yields of high purity. Pure enzyme is stable for weeks at room temperature and under pH control. Chloroperoxidase can be ionically bound to aminopropyl glass, then covalently immobilized by glutaraldehyde crosslinking. Immobilized preparations have been washed and re-used five times, and are most stable at pH 5.5-6. Like many peroxidases, chloroperoxidase will oxidize phenols and phenolics, often causing a precipitate, and can totally remove phenols at low aqueous concentrations. Chloroperoxidase incubation with the petroporphyrin component of crude oil asphaltene (fraction 5) causes a reduction or removal of the Soret band (410 nm) and the α-peak (573 nm). This petroporphyrin fraction is enriched with vanadium which poisons the chemical catalyst used in cracking crude oil.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01577650
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  • 128
    Digitale Medien
    Digitale Medien
    Polygalacturonate lyase production byThermomonospora curvata on protein-extracted lucerne fiber (1991)
    Springer
    Journal of industrial microbiology and biotechnology 7 (1991), S. 243-249 
    Details
    ISSN: 1476-5535
    Schlagwort(e): Actinomycete ; Exoenzyme ; Pectin ; Pectinase ; Protease ; Thermophile
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Summary Protein-extracted lucerne fiber was used as carbon and energy source for production of extracellular polygalacturonate lyase byThermomonospora curvata. The optimal fiber concentration was 1.5% (w/v); peal lyase activity in culture fluid occurred after 3 days growth at 53°C. During that time, lyase biosynthesis was controlled through induction; production was accelerated by adding small amounts of pectin or by grinding the fiber to 40-mesh particle size to release more inducer. After 3 days growth, lyase activity decreased; inactivation of the enzyme was delayed by the presence of 1 mM Ca or by inhibition of serine proteases with 0.05 mM phenylmethylsulfonyl fluoride. The molecular weight of the lyase produced during growth on the fiber was 35 kDa compared to 56 kDa for the enzyme produced on pure pectin. TheK m of the 35-kDa form was 0.54% pectin compared to 0.06% for the 56-kDa form. The smaller form was rapidly inactivated at 60°C, the optimal temperature for activity of the larger form.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01577651
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  • 129
    Digitale Medien
    Digitale Medien
    Purification and properties ofβ-fructofuranosidase fromAureobasidium sp. ATCC 20524 (1991)
    Springer
    Journal of industrial microbiology and biotechnology 7 (1991), S. 251-256 
    Details
    ISSN: 1476-5535
    Schlagwort(e): Fructooligosaccharide ; 1-Kestose ; Glycoprotein ; Fructosyl-transferring activity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Summary Purification and properties of two β-fructofuranosidases, which produce 1-kestose (1F-β-fructofuranosyl-sucrose) from sucrose, fromAureobasidium sp. ATCC 20524 are reported. The enzymes were purified to homogeneity by fractionations involving ethanol, calcium acetate and ammonium sulfate and DEAE-Cellulofine and Sephadex G-200 chromatography. Molecular weights of the enzymes were estimated to be about 318000 (P-1) and 346000 (P-2) daltons by gel filtration. The enzymes were glycoproteins that contained about 30% (w/v) (P-1) and 53% (w/v) (P-2) carbohydrate. The optimum pH for the enzymatic reactions were 4.5–5.5 (P-1) and 4.5–6 (P-2). The enzymes were stable over a wide pH range (4–9). The optimum reaction temperatures for both enzymes were 50–55°C and they retained more than 94% (P-1) and 98% (P-2) activities at 50°C after 15 min. TheK m values for sucrose were 0.47 M (P-1) and 0.65 M (P-2). The enzymes were inhibited by mercury, copper and lead ions as well asp-chloromercuribenzoate.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01577652
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  • 130
    Digitale Medien
    Digitale Medien
    Production of mycelial protein and cellulolytic enzymes from food wastes (1991)
    Springer
    Journal of industrial microbiology and biotechnology 7 (1991), S. 257-261 
    Details
    ISSN: 1476-5535
    Schlagwort(e): Grape waste ; Pressed apple pulp ; Single cell protein ; Cellulolytic fungi ; Cellulase
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Summary Extracted grape waster material and pressed apple pulp were tested as carbon sources forPenicillium funiculosum 515,Myrothecium verrucaria 9095 andAspergillus niger TMF-15. They were good growth substrates, especially forA. niger. When cultivated on mixed substrate in optimized nutrient medium,A. niger accumulated a product of 35% crude protein with a maximum productivity of 0.117 g protein/1/h and cellulose consumption of 90.92%.A. niger also produced the highest levels of cellulase activity. Maximum carboxymethyl cellulase and activity against filter paper were 494 units/l and 97 units/l, respectively.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01577653
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  • 131
    Digitale Medien
    Digitale Medien
    Activities ofβ-glucanases andβ-glucosidases during blastospore formation inSaccharomycopsis fibuligera (1991)
    Springer
    Journal of industrial microbiology and biotechnology 7 (1991), S. 263-268 
    Details
    ISSN: 1476-5535
    Schlagwort(e): Yeast ; β-Glucanase ; β-Glucosidase catabolite repression ; Sporulation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Summary The activities of three glycosidases, β-glucosidase and β(1,3)- and β(1,6)-glucanases have been monitored during growth and blastospore formation inSaccharomycopsis fibuligera. The assays were carried out on the cell-free culture and in a cell-free extract and a wall autolysate preparation from the growing cells. In complex medium containing 1% glucose an increase in the level of all three enzymes was associated with the transition from mycelium to blastospores. When the level of glucose was increased to 5% blastospore formation was repressed and the level of β-glucanases only increased at the end of the fermentation. The β-glucosidase activity increased during the growth phase. In a defined medium in which slow growth in a wholly yeast-like form was observed, growth was not associated with a high level of β-glucanase activity.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01577654
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  • 132
    Digitale Medien
    Digitale Medien
    Genetic control of flocculation inEscherichia coli (1991)
    Springer
    Journal of industrial microbiology and biotechnology 7 (1991), S. 279-286 
    Details
    ISSN: 1476-5535
    Schlagwort(e): Bacterial aggregation ; Induction ; Type 1 pili
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Summary Escherichia coli cells form flocs or aggregates by overproducing type 1 pili. When thepil operon is placed under the control of atac orlac promoter-operator sequence, the bacterial cells can be induced to form flocs by adding isopropyl-β-d-thiogalactopyranoside to the culture medium. This phenomenon of genetically induced flocculation can aid in the downstream processing of biological products. This paper describes the construction of two artificially controlled plasmids which cause cell flocculation. Cell aggregates 50 μm in mean diameter were obtained 1 h after the cells were induced.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01577656
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  • 133
    Digitale Medien
    Digitale Medien
    Continuous decolorization of bleached kraft effluents byCoriolus versicolor in the form of pellets (1991)
    Springer
    Journal of industrial microbiology and biotechnology 7 (1991), S. 269-277 
    Details
    ISSN: 1476-5535
    Schlagwort(e): Black liquor ; Mycelial pellet ; Ligninolytic activity ; Laccase ; Activity loss
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Summary Continuous decolorization of kraft black liquor by mycelial pellets ofCoriolus versicolor in the presence of glucose as co-substrate is discussed. A linear relationship was developed between the rate of decolorization and the liquor concentration. The rate constant was equal to 0.00961 gmyc−1 h−` at 22°C. During the continuous experiments the pellets exhibited no apparent loss of activity when the liquor concentration was in the range of 400 CU l−1 to 5000 CU l−1. However, in the repeated batch experiments a loss of activity was observed which was dependent on the initial liquor concentration. The half-life of pellets was equal to 4.7, 9.4 and 20.2 days for the initial liquor concentration of 1380, 31 780 and 6990 CU l−1, respectively. The production of the extracellular enzyme, laccase, was followed but could not be used as an indicator of the ligninolytic activity. The involvement of the intracellular enzymes ofC. versicolor in the decolorization process is described.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01577655
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  • 134
    Digitale Medien
    Digitale Medien
    Annoucements (1991)
    Springer
    Journal of industrial microbiology and biotechnology 7 (1991), S. 301-302 
    Details
    ISSN: 1476-5535
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01577659
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  • 135
    Digitale Medien
    Digitale Medien
    Influence of oxygen transfer rate and media composition on fermentation ofd-xylose byPichia stipitis NRRL Y-7124 (1991)
    Springer
    Journal of industrial microbiology and biotechnology 7 (1991), S. 287-291 
    Details
    ISSN: 1476-5535
    Schlagwort(e): Pichia stipitis ; Ethanol productivity ; Oxygen transfer rate ; Media composition ; Xylose
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Summary The optimization of ethanol production byPichia stipitis NRRL Y-7124 was analysed by ATP balance. Ethanol volumetric productivity was maximal (0.5–0.6 g/l h) only over a narrow range of oxygen transfer rates (3–5 mmol O2/l h). Trace element supplements increased ethanol volumetric productivity 20%. Biotin and thiamine did not significantly affect ethanol yield. Vitamins and trace elements were not synergistic. Organic nitrogen source from yeast extract was used for growth simultaneously to ammonia.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01577657
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  • 136
    Digitale Medien
    Digitale Medien
    Biochemical and physiological characterization of the efrotomycin fermentation (1991)
    Springer
    Journal of industrial microbiology and biotechnology 7 (1991), S. 293-299 
    Details
    ISSN: 1476-5535
    Schlagwort(e): Nocardia lactamdurans ; Secondary metabolism ; Protease ; Lipase
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Summary An efrotomycin fermentation was characterized through physical, chemical and biochemical studies. Growth of the actinomycete,Nocardia lactamdurans occurred during the first 50 h of the fermentation cycle at the expense of glucose, protein, and triglycerides. The initiation of efrotomycin biosynthesis was observed when glucose dropped to a low concentration. Upon glucose depletion, cell growth ceased and a switch in the respiratory quotient occurred. Efrotomycin biosynthesis was supported by the utilization of soybean oil and starch. Analysis of triglyceride metabolism showed that no diglycerides or monoglycerides accumulated during the fermentation. The activity of extracellular enzymes (lipase, protease, and amylase) increase during the cell growth phase and decreased significantly after 150 h. The concentrations of DNA, tetrahydro-vitamin K2 (a membrane component), and free amino acids in the supernatant increased dramatically late in the fermentation cycle (225 h), indicating massive cell lysis. During this same time period, a reduction in cellular respiratory activity and efrotomycin biosynthesis were observed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01577658
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  • 137
    Digitale Medien
    Digitale Medien
    Transcriptional organization and regulation of the nosiheptide resistance gene inStreptomyces actuosus (1991)
    Springer
    Journal of industrial microbiology and biotechnology 8 (1991), S. 1-12 
    Details
    ISSN: 1476-5535
    Schlagwort(e): Nosiheptide resistance ; Thiopeptide antibiotics ; Streptomyces ; Antitermination ; Regulation of transcription
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Summary The nosiheptide resistance gene (nshR) and a putative regulatory gene (nshA) are found together on a 2326 bpBamHI-PstI DNA fragment isolated fromStreptomyces actuosus ATCC 25421. The putative regulatory gene,nshA, situated upstream from the nosiheptide resistance gene in the 2326 bp DNA fragment, contains apparent DNA-binding and RNA-binding domains. Interruption ofnshA in the chromosome ofS. actuosus alters nosiheptide production, suggesting thatnshA is involved in regulation of nosiheptide biosynthesis. Two transcription initiation sites were found upstream ofnshA as demonstrated by high-resolution Sl nuclease mapping. A weak transcription start site fornshR was found which initiated transcription from the first nucleotide of the open reading frame. Although a stem-loop structure with apparent termination activity was found betweennshA andnshR, readthrough of transcription betweennshA andnshR was demonstrated by S1 nuclease mapping of the 3′ terminus of thenshA transcript. Time-course S1 experiments of the three promoters (nshA-pl, nshA-p2, nshR-p) indicated highly regulated differential expression of the promoters.nshA-p2 is a strong, constitutive promoter whereasnshA-pl being regulated temporally with maximal activity at 96 h. Approximately 30% of the totalnshA-p1/p2 transcript reads through the terminator and into thenshR gene, accounting for more than half of the total steady-statenshR transcript. The implications of the regulation ofnshA andnshR gene expression, as well as the expression of two other linked genes, are presented.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01575585
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  • 138
    Digitale Medien
    Digitale Medien
    Impact of present and future regulations on bioremediation (1991)
    Springer
    Journal of industrial microbiology and biotechnology 8 (1991), S. 13-22 
    Details
    ISSN: 1476-5535
    Schlagwort(e): Hazardous waste ; Regulation ; Bioremediation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Summary Innovative treatment technologies are in increasing demand to clean up the nation's existing environmental contamination. There also are mounting pressures for industry to minimize the production or generation of hazardous pollutants. Bioremediation is a viable, cost-effective treatment option for both field remediation and treatment in enclosed systems. The use of innovative treatment technologies is largely regulatory driven. Over the last two decades, at least a dozen Federal environmental statutes have been enacted and hundreds of regulations implemented to control releases of pollutants into the air, water and on land. These statutes not only have created markets for the use of treatment technologies, they also may regulate some aspect of the application of that technology. Regarding bioremediation, four statutes should be reviewed to determine if compliance is necessary before employing microorganisms in the field or in enclosed systems. This paper summarizes the Federal statutes (i.e., the Toxic Substances Control Act (TSCA); the Resource Conservation and Recovery Act (RCRA); the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA); and the Federal Plant Pest Act (FPPA)), and regulations that may impact the bioremediation industry; outlines potential markets for bioremediation that are being driven by regulations; and highlights, within the regulatory framework, promising applications for the bioremediation of hazardous wastes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01575586
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  • 139
    Digitale Medien
    Digitale Medien
    Production of pigments byMonascus purpureus in solid culture (1991)
    Springer
    Journal of industrial microbiology and biotechnology 8 (1991), S. 23-28 
    Details
    ISSN: 1476-5535
    Schlagwort(e): Pigment ; Solid culture ; Monascus purpureus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Summary The effect of physical and nutritional factors on the production of pigments byMonascus purpureus FRR 2190 was studied using cultures grown on both rice and a synthetic medium that was solidified with carrageenan and extruded into rice-like particles. Pigment yield was highly sensitive to physical parameters. Optimal pigment formation in rice cultures occurred at an initial pH of 6 and an initial moisture content of 56%. Lower moisture contents led to a large decrease in pigment concentration. Red and yellow pigment production on solidified gel media was increased up to three-fold compared to that of liquid cultures of the same medium composition, particularly when peptone was used as the sole nitrogen source. Solid state rice cultures gave the highest pigment yields.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01575587
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  • 140
    Digitale Medien
    Digitale Medien
    Production of antifungal metabolites by the ectomycorrhizal fungusPisolithus tinctorius strain SMF (1991)
    Springer
    Journal of industrial microbiology and biotechnology 8 (1991), S. 29-35 
    Details
    ISSN: 1476-5535
    Schlagwort(e): Ectomycorrhizal ; Pisolithus ; Antifungal ; Phenolic ; Fermentation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Summary An ectomycorrhizal fungus,Pisolithus tinctorius strain SMF, isolated from a basidiocarp removed from the roots of a recently fallen old growth fir in the Smoky Mountains of Tennessee, was characterized for its in vitro production of antifungal metabolites. On solid mediumP. tinctorius SMF strongly inhibited growth of strains ofFusarium solani, Geotrichum candidum, Phanerochaete chrysosporium, andVerticillium dahliae, all species known to be plant pathogens. Evidence from paired colony growth inhibition studies on agar plates indicated that production of antifungal agents byP. tinctorius SMF may be enhanced by close physical contact with other fungi. The antifungal activity ofP. tinctorius SMF was much greater than that of several culture collection strains ofP. tinctorius. The culture collection strains either showed no or very limited activity. The antifungal activity was associated with an apparently inducible metabolism ofP. tinctorius SMF and with the production of darkly colored water soluble phenolic metabolites. Small scale fermentation studies showed that the phenolics are readily producible by submerged culture fermentation. This is the first report of submerged culture production of antifungal metabolites by an ectomycorrhizal fungus.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01575588
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  • 141
    Digitale Medien
    Digitale Medien
    Improved ethanol yields through supplementation with excess assimilable nitrogen (1991)
    Springer
    Journal of industrial microbiology and biotechnology 8 (1991), S. 45-52 
    Details
    ISSN: 1476-5535
    Schlagwort(e): Excess assimilable nitrogen ; Very high gravity ; Ethanol ; Yield ; Fuel alcohol ; Brewing ; Enology
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Summary Very high gravity (VHG) worts of 24° Plato supplemented with various amounts of yeast extract (YE) were inoculated at two different levels with a commercial lager strain ofSaccharomyces cerevisiae, and the resultant beers and yeast crops were analyzed. Excess assimilable nitrogen did not result in higher viable yeast counts but did lead to increased rates of growth and increased accumulation of cell mass (partly due to higher cellular protein content). Fermentation (ethanol production) rates were significantly enhanced by YE supplementation up to 1.25% w/v, and the maximum ethanol concentrations seen were significantly higher as YE levels were increased (maximum effect at 0.75%), although YE itself was largely unfermentable. Lower ethanol yields in unsupplemented control worts could not be explained by increased carbon diversion to acetaldehyde, glycerol, or glycogen.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01575590
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  • 142
    Digitale Medien
    Digitale Medien
    The novel non-heme vanadium bromoperoxidase from marine algae: Phosphate inactivation (1991)
    Springer
    Journal of industrial microbiology and biotechnology 8 (1991), S. 37-43 
    Details
    ISSN: 1476-5535
    Schlagwort(e): Vanadium bromoperoxidase ; Phosphate inactivation ; Marine alga ; Chloramine ; Bromoperoxidase ; Chloroperoxidase
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Summary Vanadium bromoperoxidase is a naturally occurring vanadium-containing enzyme isolated from marine algae. V-BrPO catalyzes the oxidation of halides by hydrogen peroxide which can result in the halogenation of organic substrates. Bromoperoxidase activity is measured by the halogenation of monochlorodimedone (2-chloro-5,5-dimethyl-1,3-dimedone, MCD). In the absence of an organic substrate, V-BrPO catalyzes the halide-assisted disproportionation of hydrogen peroxide yielding dioxygen. The dioxygen formed is in the singlet excited state (1O2). V-BrPO is quite stable to thermal denaturation and denaturation by certain organic solvents which makes V-BrPO an excellent candidate for industrial applications. The stability of V-BrPO in the presence of strong oxidants and in the presence of phosphate is reported. Incubation of V-BrPO in phosphate buffer (1–100 mM at pH 6; 2–10 mM at pH 5) inactivates the enzyme. The inactivity can be fully restored by the addition of vanadate if excess phosphate is removed. The inactivation of V-BrPO by phosphate can be prevented by the presence of H2O2 (4–40 mM). We are currently investigating the mechanism of V-BrPO inactivation by phosphate. V-BrPO was not inactivated by HOCl (1 mM) nor H2O2. In addition V-BrPO was not inactivated under turnover conditions of 1 mM H2O2 with 0.1–1 M Cl− at pH 5 nor 2 mM H2O2 with 0.1 M Br−.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01575589
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  • 143
    Digitale Medien
    Digitale Medien
    Identification of lipolytic activity in a multitrophic population grown in wool-scour effluent (1991)
    Springer
    Journal of industrial microbiology and biotechnology 8 (1991), S. 53-58 
    Details
    ISSN: 1476-5535
    Schlagwort(e): Esterase ; Lipase ; Cholesterol esterase ; Wax esterase ; Lipolytic activity ; Wool-scour effluent
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Summary A multitrophic population established in wool-scour effluent produced esterase activity with specificity to steryl, wax and triacylglyceryl esters. The wax esterase activity peaked just prior to the esterase activity toward cholesteryl oleate andp-nitrophenol palmitate. The activity was present in both the extracellular and cell membrane fractions. Partial characterization revealed the presence of multiple esterase bands on native polyacrylamide gels. The bacterial esterase activity could be enhanced by the addition of mineral salts.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01575591
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  • 144
    Digitale Medien
    Digitale Medien
    Announcements (1991)
    Springer
    Journal of industrial microbiology and biotechnology 8 (1991), S. 69-70 
    Details
    ISSN: 1476-5535
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01575594
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  • 145
    Digitale Medien
    Digitale Medien
    Effect of pH on organic acid production byClostridium propionicum in test tube and fermentor cultures (1991)
    Springer
    Journal of industrial microbiology and biotechnology 8 (1991), S. 59-63 
    Details
    ISSN: 1476-5535
    Schlagwort(e): Clostridium propionicum ; pH ; Organic acids
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Summary Clostridum propionicum is a chemical autotroph that metabolizes alanine to propionic acid (reduction product) and acetic acid (oxidation product). The ratio of propionate/acetate predicted by the electron balance is 2:1. This study reports the effect of pH on growth and organic acid production by this organism when grown in both test tube cultures initially buffered from pH 7.0 to 5.0, and in fermentors maintained at pH 7.0 and 6.5. Highest growth and organic acid production was found at pH 7.0 in both cases. HPLC analysis showed that at pH 7.0, the ratios of propionate to acetate were 0.45:1 (stationary tube, 24 h). The highest ratio observed was 1.8:1 (stationary tube, pH 6.0, 24h). This tube produced 8.5% of the acids produced in the pH 7.0 culture tube. The identify of the major portion of the reduction products of the organism remains unknown.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01575592
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  • 146
    Digitale Medien
    Digitale Medien
    A novel antifungal from an Actinomadurae with preferential activity against the mycelial phase ofCandida albicans (1991)
    Springer
    Journal of industrial microbiology and biotechnology 8 (1991), S. 65-68 
    Details
    ISSN: 1476-5535
    Schlagwort(e): Antifungal ; Sch 40873 ; Candida albicans ; Mycelial
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Summary Sch 40873, a novel antifungal compound isolated from the fermentation broth of anActinomadura spp. was discovered in an assay designed to detect compounds with preferential activity against the invasive mycelial form ofCandida albicans. The geometric mean MIC of Sch 40873 against sevenCandida spp. in Sabouraud dextrose broth (yeast phase) was ≥58 μg/ml and in Eagles minimum essential medium (mycelial phase) was 〈0.03 μg/ml. Sch 40873 demonstrated slight in vivo topical activity in a hamster vaginal model.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01575593
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  • 147
    Digitale Medien
    Digitale Medien
    Thermostable enzymes for industrial applications (1991)
    Springer
    Journal of industrial microbiology and biotechnology 8 (1991), S. 71-81 
    Details
    ISSN: 1476-5535
    Schlagwort(e): Thermostable enzyme ; Xylanase ; Protease ; Lipase ; Glycosyl transferase
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Summary The variety of thermostable (TS) enzymes has been steadily increasing for use in industrial applications, mainly as replacements for thermolabile (TL) enzymes. For example, TS amylases fromBacillus licheniformis andBacillus stearothermophilus have replaced TL amylases fromBacillus subtilis. TS enzymes also have advantages in new areas such as cyclodextrin production. The TS cyclodextrin glycosyl transferase (CGTase) fromThermoanaerobacter sp. (95°C optimum) gives a higher productivity than the CGTase fromBacillus macerans (55°C optimum). In the area of enzymatic bleach boosting of wood pulps, a TS xylanase (Myceliophera thermophila) would be advantageous over a TL xylanase (Trichoderma reesei), due to the high temperature of the incoming pulp. Not all TS enzymes are from thermophiles; the mesophileCandida antarctica produces a TS lipase which has a temperature optimum of 90°C when immobilized. The characterization of these enzymes will be described along with comparisons to some newly described TS enzymes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01578757
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  • 148
    Digitale Medien
    Digitale Medien
    Activity of an insoluble antimicrobial quaternary amine complex in plastics (1991)
    Springer
    Journal of industrial microbiology and biotechnology 8 (1991), S. 83-89 
    Details
    ISSN: 1476-5535
    Schlagwort(e): Quaternary amine ; Insoluble antimicrobial in plastics ; Bacterial adherence ; Inhibition ofAspergillus niger
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Summary Growth and survival ofStaphylococcus aureus, Pseudomonas aeruginosa., Klebsiella pneumoniae andAspergillus niger were reduced by a low-solubility polysubstituted.-quaternary amine complex (InterseptR) processed into the matrices of ethylene vinyl acetate, polystyrene and polyethylene., Recoveries of challenge microorganisms from agar film overlays and determination of the effects of the complex on radiolabelled-leucine transport by adhered cells and bacterial biofilms were more suitable for assessing inhibitory efficacies than standard agar diffusion or serial dilution procedures.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01578758
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  • 149
    Digitale Medien
    Digitale Medien
    Use of continuous-flow UV-induced mutation technique to enhance chlorinated organic biodegradation (1991)
    Springer
    Journal of industrial microbiology and biotechnology 8 (1991), S. 99-106 
    Details
    ISSN: 1476-5535
    Schlagwort(e): Mutation ; UV ; Biodegradation ; Chlorinated organic compound
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Summary In this study, a continuous-flow UV-induced mutation (CUM) device and the CUM device coupled to a selector (CUMS) reactor were fabricated and tested for their ability to enhance the probability of obtaining populations capable of chlorinated organic biodegradation. A mixed culture of bacteria were used as the starting strain for both the CUM and CUMS processes. Populations were obtained from the CUM and CUMS systems capable of 4-chlorobenzoic acid, 2,4-dichlorobenzoic acid and chlorendic acid biodegradation. Non-UV irradiated population served as controls for the experiments and did not demonstrate chlorinated organic biodegradation over the test duration.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01578760
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  • 150
    Digitale Medien
    Digitale Medien
    Streptomycin-resistant mutant production in a continuous-flow UV mutation device (1991)
    Springer
    Journal of industrial microbiology and biotechnology 8 (1991), S. 107-112 
    Details
    ISSN: 1476-5535
    Schlagwort(e): Mutant production ; Continuous flow ; UV irradiation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Summary A continuous-flow UV-induced mutation device which incorporates starting strain cultivation, UV irradiation and mutant reproduction was conceptualized and tested in this study using streptomycin resistance as an indicator of mutant production. For the experimental conditions employed and populations used, the mutation frequency for streptomycin resistance ranged from 10−4 to 10−5 cfu/ml. These mutation frequencies are comparable with conventional batch UV mutation methods and represent a gain of 3 orders of magnitude over the spontaneous mutation frequency.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01578761
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  • 151
    Digitale Medien
    Digitale Medien
    Disturbance, starvation, and overfeeding stresses detected by microbial lipid biomarkers in high-solids high-yield methanogenic reactors (1991)
    Springer
    Journal of industrial microbiology and biotechnology 8 (1991), S. 91-98 
    Details
    ISSN: 1476-5535
    Schlagwort(e): Fatty acid ; Ether lipid ; Methanogen ; Clustering method ; Microbial stress
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Summary Microbial biomass and community structure of methanogenic anaerobic biomass reactors can be quantitatively monitored by signature, lipid analysis. The eubacterial and eukaryotic polar lipid fatty acids and the methanogen polar lipid ethers are reliable measures of their respective biomasses. The pattern of polar lipid fatty acids yields information on the community structure and metabolic state of the eubacteria and eukaryotes. These biomarker methods were applied over a 2-day feeding cycle of a highly productive batch-fed high-solids anaerobic biomass reactor. It was sampled before feeding, 6 h after feeding (disturbed)., at maximum gas production (healthy, 24 h), and after feedstock utilization (starved, 48h). Relative to the healthy condition, the disturbance of feeding significantly decreased eubacterial biomass and the proportion of unsaturated fatty acids, and increased branched fatty acids and the eubacterial stress biomarker,trans/cis 16: 1ω7. The starved condition was not significantly different from the healthy in biomass or proportions of fatty acids, but did show a significant increase in the proportion of the eubacterial stress biomarkertrans/cis 18: 1ω7. This reactor was compared to a second of the same design which had been overfed and showed significantly less productivity. The overfed reactor had a significantly lower methanogenic biomass,iso-branched fatty acids, and higher eubacterial stress markers Cy17:0 andtrans/cis 18: 1ω7 than the highly productive reactor.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01578759
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  • 152
    Digitale Medien
    Digitale Medien
    Mutants of a lovastatin-hyperproducingAspergillus terreus deficient in the production of sulochrin (1991)
    Springer
    Journal of industrial microbiology and biotechnology 8 (1991), S. 113-119 
    Details
    ISSN: 1476-5535
    Schlagwort(e): Microtiter fermentation ; Lovastatin ; Polyketide ; Strain improvement ; Screening
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Summary A lovastatin-hyperproducing culture ofAspergillus terreus was shown to produce several co-metabolites extracted from whole broth. The predominant co-metabolite was the benzophenone, sulochrin, reported to arise from a polyketide biosynthetic pathway. This compound was targeted for elimination by classical mutagenesis and screening. A surface culture method employing microtiter, plates was used to ferment mutants for the primary screen. Qualitative determinations of lovastatin and sulochrin production were achieved by high-performance thin-layer chromatography. A mutant, strain AH6, which produced lovastatin titers equivalent to the parent culture and no detectable sulochrin was isolated. In addition, a lovastatin-hyperproducing mutant designated CB4 was capable of producing 16% more lovastatin and 30% less sulochrin than the parent culture in shake flask fermentations. In a pilot-scale 250-gallon fermentation, strain CB4 gave a 20% increase in lovastatin titer while producing 83% less sulochrin than the parent culture.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01578762
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  • 153
    Digitale Medien
    Digitale Medien
    The use of particle concentration fluorescence immunoassay technology for the analysis of rDNA products (1991)
    Springer
    Journal of industrial microbiology and biotechnology 8 (1991), S. 121-125 
    Details
    ISSN: 1476-5535
    Schlagwort(e): Immunoassay ; Particle Concentration Fluorescence Immunoassay ; rDNA product analysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Summary The electrophoretic and immunological techniques typically used to detect potentially useful biopharmaceutical proteins are sensitive with detection limits in the nanogram range. However, quantitation of a recombinant protein can be cumbersome and involve large numbers of samples throughout process optimization schemes. Although electrophoretic methods (i.e., SDS-PAGE and Western blots) now avail themselves to quantitation by densitometry, these techniques are time consuming because of the lack of appropriate automated systems. Biological activity assays, when available, often require relatively pure material and are not suitable for analyzing and quantitating impure or semi-purified samples, typical of the fermentation milieu. The optimization of several rDNA-derived protein systems from both prokaryotic and eukaryotic hosts has been completed using PCFIA, a rapid, sensitive system with high throughput. The development of Particle Concentration Fluorescence Immunoassay (CFIA) procedures for several of these rDNA-derived proteins of interest as potential biopharmaceuticals (e.g., α-1-antitrypsin, tPA, soluble CD4, and a malaria vaccine candidate) are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01578763
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  • 154
    Digitale Medien
    Digitale Medien
    L-lysine production at 65°C by auxotrophic-regulatory mutants ofBacillus stearothermophilus (1991)
    Springer
    Journal of industrial microbiology and biotechnology 8 (1991), S. 127-131 
    Details
    ISSN: 1476-5535
    Schlagwort(e): Bacillus stearothermophilus ; L-Lysine production ; Aspartokinase activity ; Enzyme regulation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Summary The amino acid L-lysine was produced from auxotrophic-regulatory mutants ofBacillus stearothermophilus at a temperature of 60–65°C. One of the mutants (AEC 12 A5, S-(2-aminoethyl)-cysteiner, homoserine−), produced L-lysine at the concentration of 7.5 g/l in shaken flasks in minimal medium containing 5% glucose. Culture conditions for optimizing L-lysine production were not investigated. The aspartokinase activity of the wild strainB. stearothermophilus Zu 183 was inhibited by lysine alone and by threonine plus lysine. AEC resistant mutants showed an aspartokinase activity genetically desensitized to the feedback inhibition. Optimal temperature and pH of aspartokinase were 45°C and 9.5, respectively. The data provide significant evidence that mutants of the speciesB. stearothermophilus have a potential value for amino acid production.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01578764
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  • 155
    Digitale Medien
    Digitale Medien
    Elektrophoretische Untersuchungen der Superoxiddismutase-Isoenzyme beim hessischen Rotwild (Cervus elaphus L.) (1991)
    Springer
    European journal of wildlife research 37 (1991), S. 35-39 
    Details
    ISSN: 1439-0574
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Beschreibung / Inhaltsverzeichnis: Summary The enzyme superoxide dismutase (SOD, E.C. 1.15.1.1.) was investigated electrophoretically in 196 muscle-, heart- and liver samples of red deer from the forest Reinhardswald, a game preserve in Hessen, Western Germany. The banding patterns in the electropherograms can be interpreted as products of two loci, one of them coding for an enzyme of dimeric quarternary structure. The observed genotypic distribution does not fit Hardy-Weinberg expectations. An excess of heterozygotes is observed. This phenomenon is explained by a sample bias caused by deer management. This study is the basis for further wide ranging investigations, intended to evaluate consequences of wildlife management on the genetic structure of this deer population.
    Kurzfassung: Résumé L'enzyme Superoxiddismutase (SOD, E.C. 1.15.1.1.) a été étudié par électrophorèse continue et focalisation isoélectrique de 196 échantillons d'organes de cerfs provenant de la Réserve cynégétique de la Reinhardswald en Hesse. Les bandes électrophorétiques-types peuvent être interprétées comme étant le résultat de l'action de deux loci, le locus 1 codant un enzyme avec structure quaternaire dimérique. Un test de χ2 révèle que les fréquences observées du génotype s'écartent significativement des fréquences attendues, avec un excédent des hétérozygotes. Cette situation s'explique par le lâcher de cerfs hongrois dans la population autochtone avec, à chaque fois, des fréquences alléliques opposées et un tir sélectif. Ces recherches serviront à fonder des recherches ultérieures sur cette population en faisant appel à d'autres iso-enzymes afin de suivre les effets de la gestion cynégétique sur des paramètres génétiques.
    Notizen: Zusammenfassung Das Enzym Superoxiddismutase (SOD, E.C. 1.15.1.1.) wurde mittels der kontinuierlichen Elektrophorese und der isoelektrischen Fokussierung anhand von 196 Rotwild-Organproben aus dem Wildschutzgebiet Reinhardswald/Hessen untersucht. Das Bandenmuster im Elektropherogramm kann als das Produkt zweier Loci interpretiert werden, wobei Genort-1 ein Enzym mit dimerer Quartärstruktur codiert. Im Chi2-Test zeigt sich eine signifikante Abweichung der beobachteten von den erwarteten Genotyphäufigkeiten, ein Überschuß an Heterozygoten wurde beobachtet. Dieser Zustand ist durch das Aussetzen von ungarischem Rotwild in die autochthone Population mit jeweils entgegengerichteten Allelfrequenzen und selektivem Abschuß erklärbar. Die Untersuchungen dienen als Grundstein für nachfolgende Untersuchungen an dieser Population unter Verwendung weiterer Isoenzyme, um Auswirkungen des jagdlichen Managements auf genetische Parameter zu verfolgen.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02241645
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  • 156
    Digitale Medien
    Digitale Medien
    IV. Referate (1991)
    Springer
    European journal of wildlife research 37 (1991), S. 67-68 
    Details
    ISSN: 1439-0574
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02241651
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  • 157
    Digitale Medien
    Digitale Medien
    Untersuchungen zur genetischen Situation des Damwildes in Nordrhein-Westfalen (1991)
    Springer
    European journal of wildlife research 37 (1991), S. 69-77 
    Details
    ISSN: 1439-0574
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Beschreibung / Inhaltsverzeichnis: Summary In order to determine the genetic variability of fallow deer in hunting districts in Northrhine-Westphalia, 6 isoenzyme systems from liver tissue of 56 sample animals were analyzed using gel electrophoresis. Of the 11 gene loci studied, 8 were monomorphic. The average heterozygotic rate of all populations was 1.4 %, the average number of alleles per gene loci was 1.37. No significant differences were found among the populations. Measures concerning the management of fallow deer for hunting are discussed.
    Kurzfassung: Résumé Afin d'établir la variabilité génétique du Daim(Dama dama) sur le plan biochimique dans des territoires de Rhénanie-Westphalie, on a anlysé sur un ensemble de 56 individus six systèmes d'isoenzymes du tissu hépatique par électrophorèse. Des 11 loci géniques recensés, 8 étaient monomorphes. Le taux moyen d'hétérozygotie de toutes les populations s'élevait à 1,4 %, le nombre moyen d'allèles par locus génique à 1,37. Aucune différence significative ne fut décelée entre les populations. Une discussion porte sur les mesures de gestion cynégétique du Daim.
    Notizen: Zusammenfassung Um die biochemisch erfaßbare genetische Variabilität von Damwild (Dama dama) in Revieren in Nordrhein-Westfalen zu ermitteln, wurden bei insgesamt 56 Individuen sechs Isoenzymsysteme aus Lebergewebe gelelektrophoretisch analysiert. Von den erfaßten 11 Genorten waren 8 monomorph. Die durchschnittliche Heterozygotierate aller Populationen betrug 1,4 %, die durchschnittliche Anzahl Allele pro Genort 1,37. Es fanden sich keine signifikanten Unterschiede zwischen den Populationen. Maßnahmen zur jagdlichen Bewirtschaftung des Damwildes werden diskutiert.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02241671
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  • 158
    Digitale Medien
    Digitale Medien
    Evaluation of risk concepts in partial duration series (1991)
    Springer
    Stochastic environmental research and risk assessment 5 (1991), S. 1-16 
    Details
    ISSN: 1436-3259
    Schlagwort(e): Partial duration series ; unbiased risk ; Bayesian risk
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung , Energietechnik , Geographie , Geologie und Paläontologie
    Notizen: Abstract Conventional design practice aims at obtaining optimal estimates of floods with specified exceedance probabilities. Such estimates are, however, known on the average to be exceeded more frequently than expected. Alternatively, methods focusing on the expected exceedance probability can be used. Two different methods are considered here; the first is based on the sample distribution of true exceedance probabilities. The second is a Bayesian analogue using the likelihood function and a noninformative prior to describe the variability of exceedance probabilities. Appropriate analytical solutions are presented in both cases using the partial duration series approach.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01544174
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  • 159
    Digitale Medien
    Digitale Medien
    Derivation of bivariate probability density functions with exponential marginals (1991)
    Springer
    Stochastic environmental research and risk assessment 5 (1991), S. 55-68 
    Details
    ISSN: 1436-3259
    Schlagwort(e): Bivariate probability distribution ; random variables ; zero marginals ; Finch-Groblicki method
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung , Energietechnik , Geographie , Geologie und Paläontologie
    Notizen: Abstract A vivariate probability density function (pdf),f(x 1,x 2), admissible for two random variables (X 1,X 2), is of the form $$f(x_1 x_2 ) = f_1 (x_1 )f_2 (x_2 )[1 + \rho \{ F_1 (x_1 ),F_2 (x_2 )\} ]$$ where ρ(u, v) (u=F 1(x 1),v=F 2(x 2)) is any function on the unit square that is 0-marginal and bounded below by−1 andF 1(x 1) andF 2(x 2) are cumulative distribution functions (cdf) of marginal probability density functionsf 1(x 1) andf 2(x 2). The purpose of this study is to determinef(x 1,x 2) for different forms of ρ(u,v). By considering the rainfall intensity and the corresponding depths as dependent random variables, observed and computed probability distributionsF 1(x 1),F(x 1/x 2),F 2(x 2), andF(x 2/x 1) are compared for various forms of ρ(u,v). Subsequently, the best form of ρ(u,v) is specified.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01544178
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  • 160
    Digitale Medien
    Digitale Medien
    Entropy estimation of hydrological extremes (1991)
    Springer
    Stochastic environmental research and risk assessment 5 (1991), S. 77-87 
    Details
    ISSN: 1436-3259
    Schlagwort(e): Flood ; random ; distribution ; estimation ; probability ; entropy ; fractile constraints
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung , Energietechnik , Geographie , Geologie und Paläontologie
    Notizen: Abstract The method of Relative Entropy with Fractile constraints (REF method) is explained and applied to model extreme compound hydrological phenomena, such as extreme sea levels under storm conditions. Also presented is a simple method of Tail Entropy Approximation (TEA), which amounts to a correction of traditional statistical estimates for extreme observations. Distribution assumptions are necessary but downplayed in the REF method, relegating the prior distribution to the role of an extrapolation function. The estimates are objective in an information-theoretical sense. They also satisfy a strict requirement of self-consistency that is generally not satisfied by standard statistical methods: invariance under monotonic transformations of the random variable. Historical records of storm surge levels in the Netherlands and annual maximum tidal heights for Sheerness, UK, are used as examples. Comparison is made with distributions obtained using other methods. It is concluded that the tail entropy approximation provides simple, objective estimates of extremes in the tail beyond the range of observations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01544180
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  • 161
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    Digitale Medien
    On the use of Empirical Orthogonal Function (EOF) analysis in the simulation of random fields (1991)
    Springer
    Stochastic environmental research and risk assessment 5 (1991), S. 125-134 
    Details
    ISSN: 1436-3259
    Schlagwort(e): Empirical Orthogonal Function analysis ; random fields ; simulation ; non-homogeneous fields
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung , Energietechnik , Geographie , Geologie und Paläontologie
    Notizen: Abstract In several fields of Geophysics, such as Hydrology, Meteorology or Oceanography, it is often useful to generate random fields, displaying the same variabilitity as the observed variables. Usually, these synthetic data are used as forcing fields into numerical models, to test the sensitivity of their outputs to the variability of the inputs. Examples can be found in subsurface or surface Hydrology and in Meteorology with General Circulation Models (GCM). Different techniques have already been proposed, often based on the spectral representation of the random process, with, usually, assumptions of stationarity. This paper suggests that Empirical Orthogonal Function (EOF) analysis, which leads to the decomposition of the covariance kernel on the set of its eigen-functions, is a possible answer to this problem. The convergence and accuracy of the method are shown to depend mainly on the number of EOFs retained in the expansion of the covariance kemel. This result is confirmed by a comparison with the turning band method and a matrix technique. Furthermore, a synthetic example of non-homogencous fields shows the interest of EOF analysis in the direct simulation of such fields.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01543054
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  • 162
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    Digitale Medien
    A univariate model for long-term streamflow forecasting (1991)
    Springer
    Stochastic environmental research and risk assessment 5 (1991), S. 173-188 
    Details
    ISSN: 1436-3259
    Schlagwort(e): Entropy ; spectral analysis ; streamflow forecasting ; univariate model
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung , Energietechnik , Geographie , Geologie und Paläontologie
    Notizen: Abstract This paper, the first in a series of two, employs the principle of maximum entropy (POME) via maximum entropy spectral analysis (MESA) to develop a univariate model for long-term streamflow forecasting. Three cases of streamflow forecasting are investigated: forward forecasting, backward forecasting (or reconstruction) and intermittent forecasting (or filling in missing records). Application of the model is discussed in the second paper.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01544056
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  • 163
    Digitale Medien
    Digitale Medien
    Modeling kinetic non-equilibrium using the first two moments of the residence time distribution (1991)
    Springer
    Stochastic environmental research and risk assessment 5 (1991), S. 155-171 
    Details
    ISSN: 1436-3259
    Schlagwort(e): Kinetic non-equilibrium ; residence time ; spatially variable chemical reactions
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung , Energietechnik , Geographie , Geologie und Paläontologie
    Notizen: Abstract A method for simulating field scale transport of kinetically adsorbing solutes is described. The non-equilibrium adsorption is modeled as a birth and death process and is coupled with the particle tracking approach using the first two moments of the distribution of the particle residence time, i.e., the time that a solute particle stays in the liquid phase. A single residence time distribution, regardless of the initial and final phase, is demonstrated to yield an accurate description of chemical kinetics in the vast majority of field scale problems. The first two moments of the residence time distribution are derived as a function of chemical reaction rates and the transport time interval Δt. It is shown that the first moment of the residence time represents a measure of the speed of the chemical reaction relative to the transport time scale Δt which is chosen depending on the velocity field. The second moment of the residence time reflects the relative importance of the chemical kinetics versus local equilibrium conditions for the given transport time step Δt. The simulated spatial moments of the contaminant plume are compared in the one-dimensional case with available analytical solutions to demonstrate the accuracy of the proposed technique. A two-dimensional case for stratified formations is presented to study the transport behavior for heterogeneous velocity fields and variable distribution coefficient, hypothesized as being negatively correlated with hydraulic conductivity. The results show that the enhanced plume spreading and the statistics of the arrival time distribution appear to be more sensitive to the spatially variable distribution coefficient than to the kinetics alone. In fact, the second spatial moment was almost doubled in the case of spatially variable distribution coefficient.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01543057
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  • 164
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    Digitale Medien
    Stochastic partial differential equations in groundwater hydrology (1991)
    Springer
    Stochastic environmental research and risk assessment 5 (1991), S. 239-251 
    Details
    ISSN: 1436-3259
    Schlagwort(e): Parameter estimation ; maximum likelihood estimation ; stochastic partial differential equation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung , Energietechnik , Geographie , Geologie und Paläontologie
    Notizen: Abstract Part I of this series of two papers (Unny, 1989) dealt with the theoretical derivation of the moment equations for the stochastic partial differential equation in the water table depth forced by stochastic rainfall input. Part I also developed a maximum likelihood estimation procedure for parameter determination. The primary aim of the present manuscript is the application of the parameter estimation procedure to the Borden aquifer, an aquifer designated as an experimental site, where extensive field measurements have been carried out. Estimates of hydraulic conductivity and transmissivity for the Borden aquifer, derived from the maximum likelihood algorithm, have been compared with estimates obtained by “traditional” procedures. The paper also presents the simulated solution of the governing differential equation in the one dimensional problem applied to the Borden aquifer.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01544060
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  • 165
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    Digitale Medien
    Technical reports (1991)
    Springer
    Stochastic environmental research and risk assessment 5 (1991), S. 280-294 
    Details
    ISSN: 1436-3259
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung , Energietechnik , Geographie , Geologie und Paläontologie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01543136
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  • 166
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    Digitale Medien
    Drought monitoring (1991)
    Springer
    Stochastic environmental research and risk assessment 5 (1991), S. 261-266 
    Details
    ISSN: 1436-3259
    Schlagwort(e): Drought ; drought indices
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung , Energietechnik , Geographie , Geologie und Paläontologie
    Notizen: Abstract Drought detection, monitoring and indices are closely related to its definition. The specific definition chosen for a particular drought analysis will affect the procedures one uses in drought detection and monitoring. The traditional Palmer Drought Severity Index (PDSI) has been proven to be ineffective in regions of predominantly irrigated agriculture. The recently developed ALERT (Automated Local Evaluation in Real Time) system is proposed for use in monitoring the spatial and temporal variations of drought in real time. The ALERT system uses standardized instruments, radio frequencies, software and hardware. It was originally developed as a flash flood waming system by local flood control districts and the National Weather Service. However, now it has expanded to over 100 other uses in the areas of natural and man-made disaster detection and warning. The successful ALERT system indicates the need for the continued development of a national drought monitoring index that is applicable to a wide range of climate, hydrologic and water resource environments.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01543134
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  • 167
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    Digitale Medien
    An exact solution of solute transport by one-dimensional random velocity fields (1991)
    Springer
    Stochastic environmental research and risk assessment 5 (1991), S. 45-54 
    Details
    ISSN: 1436-3259
    Schlagwort(e): Solute transport ; random velocity ; Lagrangian description ; travel time ; nonlinear effects
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung , Energietechnik , Geographie , Geologie und Paläontologie
    Notizen: Abstract The problem of one-dimensional transport of passive solute by a random steady velocity field is investigated. This problem is representative of solute movement in porous media, for example, in vertical flow through a horizontally stratified formation of variable porosity with a constant flux at the soil surface. Relating moments of particle travel time and displacement, exact expressions for the advection and dispersion coefficients in the Focker-Planck equation are compared with the perturbation results for large distances. The first- and second-order approximations for the dispersion coefficient are robust for a lognormal velocity field. The mean Lagrangian velocity is the harmonic mean of the Eulerian velocity for large distances. This is an artifact of one-dimensional flow where the continuity equation provides for a divergence free fluid flux, rather than a divergence free fluid velocity.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01544177
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  • 168
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    Digitale Medien
    Stochastic overland flows (1991)
    Springer
    Stochastic environmental research and risk assessment 5 (1991), S. 89-104 
    Details
    ISSN: 1436-3259
    Schlagwort(e): Overland flows ; nonlinear SPDE ; evolutionary probability distributions
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung , Energietechnik , Geographie , Geologie und Paläontologie
    Notizen: Abstract A theoretical solution framework to the nonlinear stochastic partial differential equations (SPDE) of the kinematic wave and diffusion wave models of overland flows under stochastic inflows/outflows, stochastic surface roughness field and stochastic state of flows was obtained. This development was realized by means of an eigenfunction representation of the time-space overland flow depths, and by transforming the problem into the phase space. By using Van Kampen's lemma and the cumulant expansion theory of Kubo-Van Kampen-Fox, the deterministic partial differential equation (PDE) for the evolutionary probability density function (pdf) of overland flow depths was finally obtained. Once this deterministic PDE is solved for the time-varying pdf of overland flow depths, then the time-space varying pdf of overland flow depths can be obtained by a transformation given in the text. In this solution framework it is possible to incorporate the stochastic dynamic behavior of the parameters and of the forcing functions of the overland flow process. For example, not only the individual rainfall duration and fluctuating rain intensity characteristics but also the sequential behavior of rainfall patterns is incorporated into the evolutionary probability density function of overland flow depths.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01543052
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  • 169
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    Digitale Medien
    Effort associated with a class of random optimization methods (1991)
    Springer
    Mathematical programming 50 (1991), S. 91-98 
    Details
    ISSN: 1436-4646
    Schlagwort(e): 65K10 ; 62E15 ; 60F99 ; Random optimization ; expected length
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract When differentiability is not assumed random procedures can be successfully used to estimate the extreme values of a given function. For a class of such algorithms we treat the problem of estimating the mean effort.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01594927
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  • 170
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    Digitale Medien
    Limiting behavior of the affine scaling continuous trajectories for linear programming problems (1991)
    Springer
    Mathematical programming 50 (1991), S. 29-51 
    Details
    ISSN: 1436-4646
    Schlagwort(e): Interior-point methods ; linear programming ; Karmarkar's algorithm ; logarithmic barrier function ; affine scaling algorithms ; continuous trajectories for linear programming
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract We consider the continuous trajectories of the vector field induced by the primal affine scaling algorithm as applied to linear programming problems in standard form. By characterizing these trajectories as solutions of certain parametrized logarithmic barrier families of problems, we show that these trajectories tend to an optimal solution which in general depends on the starting point. By considering the trajectories that arise from the Lagrangian multipliers of the above mentioned logarithmic barrier families of problems, we show that the trajectories of the dual estimates associated with the affine scaling trajectories converge to the so called ‘centered’ optimal solution of the dual problem. We also present results related to asymptotic direction of the affine scaling trajectories. We briefly discuss how to apply our results to linear programs formulated in formats different from the standard form. Finally, we extend the results to the primal-dual affine scaling algorithm.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01594923
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  • 171
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    Digitale Medien
    Convergence of a generalized subgradient method for nondifferentiable convex optimization (1991)
    Springer
    Mathematical programming 50 (1991), S. 75-80 
    Details
    ISSN: 1436-4646
    Schlagwort(e): Subgradient method ; ε-subgradient ; nondifferentiable optimization
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract A generalized subgradient method is considered which uses the subgradients at previous iterations as well as the subgradient at current point. This method is a direct generalization of the usual subgradient method. We provide two sets of convergence conditions of the generalized subgradient method. Our results provide a larger class of sequences which converge to a minimum point and more freedom of adjustment to accelerate the speed of convergence.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01594925
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  • 172
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    Digitale Medien
    Concave minimization via conical partitions and polyhedral outer approximation (1991)
    Springer
    Mathematical programming 50 (1991), S. 259-274 
    Details
    ISSN: 1436-4646
    Schlagwort(e): Concave minimization ; global optimization ; nonlinear programming ; nonconvex programming ; branch-and-bound ; outer approximation ; cutting planes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract An algorithm is proposed for globally minimizing a concave function over a compact convex set. This algorithm combines typical branch-and-bound elements like partitioning, bounding and deletion with suitably introduced cuts in such a way that the computationally most expensive subroutines of previous methods are avoided. In each step, essentially only few linear programming problems have to be solved. Some preliminary computational results are reported.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01594938
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  • 173
    Digitale Medien
    Digitale Medien
    Use of dynamic trees in a network simplex algorithm for the maximum flow problem (1991)
    Springer
    Mathematical programming 50 (1991), S. 277-290 
    Details
    ISSN: 1436-4646
    Schlagwort(e): Algorithms ; complexity ; data structures ; dynamic trees ; graphs ; linear programming ; maximum flow ; network flow ; network optimization
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract Goldfarb and Hao (1990) have proposed a pivot rule for the primal network simplex algorithm that will solve a maximum flow problem on ann-vertex,m-arc network in at mostnm pivots and O(n 2 m) time. In this paper we describe how to extend the dynamic tree data structure of Sleator and Tarjan (1983, 1985) to reduce the running time of this algorithm to O(nm logn). This bound is less than a logarithmic factor larger than those of the fastest known algorithms for the problem. Our extension of dynamic trees is interesting in its own right and may well have additional applications.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01594940
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  • 174
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    Digitale Medien
    The primal-dual algorithm as a constraint-set-manipulation device (1991)
    Springer
    Mathematical programming 50 (1991), S. 343-357 
    Details
    ISSN: 1436-4646
    Schlagwort(e): Primal—dual algorithm ; continuity of value functional ; asymptotic feasibility ; constraint-set-manipulation ; entropy maximization
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract A general primal—dual algorithm for linearly constrained optimization problems is formulated in which the dual variables are updated by a dual algorithmic operator. Convergence is proved under the assumption that the dual algorithmic operator implies asymptotic feasibility of the primal iterates with respect to the linear constraints. A general result relating the minimal values of an infinite sequence of constrained problems to the minimal value of a limiting problem (constrained by the limit of the sequence of constraints sets) is established and invoked. The applicability of the general theory is demonstrated by analyzing a specific dual algorithmic operator. This leads to the “MART” algorithm for constrained entropy maximization used in image reconstruction from projections.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01594943
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  • 175
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    Digitale Medien
    An $$O(\sqrt n L)$$ iteration potential reduction algorithm for linear complementarity problems (1991)
    Springer
    Mathematical programming 50 (1991), S. 331-342 
    Details
    ISSN: 1436-4646
    Schlagwort(e): Potential reduction algorithm ; linear complementarity problem ; interior point algorithm ; Karmarkar's algorithm ; path of centers ; central trajectory
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract This paper proposes an interior point algorithm for a positive semi-definite linear complementarity problem: find an (x, y)∈ℝ 2n such thaty=Mx+q, (x,y)⩾0 andx T y=0. The algorithm reduces the potential function $$f(x,y) = (n + \sqrt n )\log x^T y - \sum\limits_{i = 1}^n {\log x_i y_i } $$ by at least 0.2 in each iteration requiring O(n 3) arithmetic operations. If it starts from an interior feasible solution with the potential function value bounded by $$O(\sqrt n L)$$ , it generates, in at most $$O(\sqrt n L)$$ iterations, an approximate solution with the potential function value $$ - O(\sqrt n L)$$ , from which we can compute an exact solution in O(n 3) arithmetic operations. The algorithm is closely related with the central path following algorithm recently given by the authors. We also suggest a unified model for both potential reduction and path following algorithms for positive semi-definite linear complementarity problems.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01594942
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  • 176
    Digitale Medien
    Digitale Medien
    Finite termination of the proximal point algorithm (1991)
    Springer
    Mathematical programming 50 (1991), S. 359-366 
    Details
    ISSN: 1436-4646
    Schlagwort(e): Sharp minima ; proximal point ; finite termination
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract This paper concerns the notion of a sharp minimum on a set and its relationship to the proximal point algorithm. We give several equivalent definitions of the property and use the notion to prove finite termination of the proximal point algorithm.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01594944
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  • 177
    Digitale Medien
    Digitale Medien
    Karmarkar's linear programming algorithm and Newton's method (1991)
    Springer
    Mathematical programming 50 (1991), S. 291-330 
    Details
    ISSN: 1436-4646
    Schlagwort(e): Karmarkar's algorithm ; modified Newton's method ; global Newton's method ; projective transformation ; logarithmic barrier function ; nonlinear optimization
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract This paper describes a full-dimensional version of Karmarkar's linear programming algorithm, theprojective scaling algorithm, which is defined for any linear program in ℝ n having a bounded, full-dimensional polytope of feasible solutions. If such a linear program hasm inequality constraints, then it is equivalent under an injective affine mappingJ:ℝ n →ℝ m to Karmarkar's original algorithm for a linear program in ℝ m havingm—n equality constraints andm inequality constraints. Karmarkar's original algorithm minimizes a potential functiong(x), and the projective scaling algorithm is equivalent to that version of Karmarkar's algorithm whose step size minimizes the potential function in the step direction. The projective scaling algorithm is shown to be a global Newton method for minimizing a logarithmic barrier function in a suitable coordinate system. The new coordinate system is obtained from the original coordinate system by a fixed projective transformationy = Ф(x) which maps the hyperplaneH opt ={x:〈c, x〉 =c 0} specified by the optimal value of the objective function to the “hyperplane at infinity”. The feasible solution set is mapped underФ to anunbounded polytope. Letf LB(y) denote the logarithmic barrier function associated to them inequality constraints in the new coordinate system. It coincides up to an additive constant with Karmarkar's potential function in the new coordinate system. Theglobal Newton method iterate y * for a strictly convex functionf(y) defined on a suitable convex domain is that pointy * that minimizesf(y) on the search ray {y+λ v N(y): λ≧0} wherev N(y) =−(∇2 f(y))−1(∇f(y)) is the Newton's method vector. If {x (k)} are a set of projective scaling algorithm iterates in the original coordinate system andy (k) =Ф(x (k)) then {y (k)} are a set of global Newton method iterates forf LB(y) and conversely. Karmarkar's algorithm with step size chosen to minimize the potential function is known to converge at least at a linear rate. It is shown (by example) that this algorithm does not have a superlinear convergence rate.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01594941
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  • 178
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    Digitale Medien
    Sequential quadratic programming for certain parameter identification problems (1991)
    Springer
    Mathematical programming 51 (1991), S. 281-305 
    Details
    ISSN: 1436-4646
    Schlagwort(e): Sequential quadratic programming ; parameter identification ; 65K10 ; 65H10 ; 49D37
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract We analyze the method of sequential quadratic programming for equality constrained minimization problems in Hilbert spaces of functions, and for the discrete approximations of such problems in the context of an elliptic parameter identification problem. We show how the discretization can be constructed so as to preserve the convergence behavior of the iterates for the infinite dimensional problem in the finite dimensional approximations. We use the structure of the parameter identification problem to reduce the size of the linear system for the SQP step and verify nondegeneracy of the constraints.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01586941
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  • 179
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    Digitale Medien
    Penalization in non-classical convex programming via variational convergence (1991)
    Springer
    Mathematical programming 51 (1991), S. 307-331 
    Details
    ISSN: 1436-4646
    Schlagwort(e): Convex programming ; epi-convergence ; Mosco-convergence ; penalization ; perturbation ; proximal regularization ; variational convergence
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract A penalty method for convex functions which cannot necessarily be extended outside their effective domains by an everywhere finite convex function is proposed and combined with the proximal method. Proofs of convergence rely on variational convergence theory.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01586942
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  • 180
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    Digitale Medien
    On rates of convergence and asymptotic normality in the multiknapsack problem (1991)
    Springer
    Mathematical programming 51 (1991), S. 349-358 
    Details
    ISSN: 1436-4646
    Schlagwort(e): 60F05 ; 60G50 ; 90C10 ; Multiknapsack value function ; Lagrangean relaxation ; asymptotic characterization ; uniform strong law of large numbers ; uniform law of the iterated logarithm ; Vapnik—Chervonenkis class ; asymptotic normality
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract In Meanti et al. (1990) an almost sure asymptotic characterization has been derived for the optimal solution value as function of the knapsack capacities, when the profit and requirement coefficients of items to be selected from are random variables. In this paper we establish a rate of convergence for this process using results from the theory of empirical processes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01586944
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  • 181
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    Digitale Medien
    Directional derivative estimates for the optimal value function of a quasidifferentiable programming problem (1991)
    Springer
    Mathematical programming 51 (1991), S. 333-348 
    Details
    ISSN: 1436-4646
    Schlagwort(e): Quasidifferential calculus ; nonlinear nonsmooth optimization ; stability theory ; decomposition
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract This paper is concerned with the optimal value function arising in the primal decomposition of a quasidifferentiable programming problem. In particular, estimates for the upper Dini directional derivative of this function are derived. They involve certain “Lagrange multipliers” occurring in the necessary minimum conditions to the lower level problems. This study generalizes some previously published results on this subject.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01586943
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  • 182
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    Digitale Medien
    The symmetric traveling salesman polytope and its graphical relaxation: Composition of valid inequalities (1991)
    Springer
    Mathematical programming 51 (1991), S. 359-400 
    Details
    ISSN: 1436-4646
    Schlagwort(e): Traveling salesman ; polytope ; facet ; composition of facets ; inequality ; graph ; Hamilton cycle ; tour
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract The graphical relaxation of the Traveling Salesman Problem is the relaxation obtained by requiring that the salesman visit each city at least once instead of exactly once. This relaxation has already led to a better understanding of the Traveling Salesman polytope in Cornuéjols, Fonlupt and Naddef (1985). We show here how one can compose facet-inducing inequalities for the graphical traveling salesman polyhedron, and obtain other facet-inducing inequalities. This leads to new valid inequalities for the Symmetric Traveling Salesman polytope. This paper is the first of a series of three papers on the Symmetric Traveling Salesman polytope, the next one studies the strong relationship between that polytope and its graphical relaxation, and the last one applies all the theoretical developments of the two first papers to prove some new facet-inducing results.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01586945
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  • 183
    Digitale Medien
    Digitale Medien
    Facets of two Steiner arborescence polyhedra (1991)
    Springer
    Mathematical programming 51 (1991), S. 401-419 
    Details
    ISSN: 1436-4646
    Schlagwort(e): Steiner trees ; arborescences ; polyhedral theory ; facets ; lifting and composition of facets
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract The Steiner arborescence (or Steiner directed tree) problem concerns the connection of a set of target vertices of a digraph to a given root vertex. This problem is known to be NP-hard. In the present paper we study the facial structure of two polyhedra associated with the problem. Several classes of valid inequalities are considered, and a new class with arbitrarily large coefficients is introduced. All these inequalities are shown to define distinct facets of both the Steiner polyhedra considered. This is achieved by exploiting two lifting theorems which also allow generalization of the new inequalities. Composition theorems are finally given and used to derive large families of new facet-inducing inequalities with exponentially large coefficients.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01586946
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  • 184
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    Digitale Medien
    Corrigenda (1991)
    Springer
    Mathematical programming 51 (1991), S. 421-421 
    Details
    ISSN: 1436-4646
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01586947
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  • 185
    Digitale Medien
    Digitale Medien
    Branch and bound with estimation based on pseudo-shadow-prices (1991)
    Springer
    Mathematical programming 52 (1991), S. 59-69 
    Details
    ISSN: 1436-4646
    Schlagwort(e): Integer programming ; branch and bound ; pseudo-shadow-prices
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract During a branch and bound search of an integer programme, variables may be declared fixed, and rows may be declared redundant. The purpose of this paper is to report some results from forcing such fixed variables out of the basis in every node of a branch and bound search. At the same time non-basic slacks at zero activity on redundant rows are forced into the basis. Both changes consume computer time, but result in a less dense basis and in some cases in better branching.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01582880
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  • 186
    Digitale Medien
    Digitale Medien
    Optimal schedule for cancer chemotherapy (1991)
    Springer
    Mathematical programming 52 (1991), S. 11-17 
    Details
    ISSN: 1436-4646
    Schlagwort(e): Modeling ; cancer ; optimization ; optimal control ; drug delivery
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract In this paper we consider the problems of modeling the tumor growth and optimize the chemotherapy treatment. A biologically based model is used with the goal of solving an optimization problem involving discrete delivery of antineoplastic drugs. Our model is formulated via compartmental analysis in order to take into account the cell cycle. The cost functional measures not only the final size of the tumor but also the total amount of drug delivered. We propose an algorithm based on the discrete maximum principle to solve the optimal drug schedule problem. Our numerical results show nice interpretations from the medical point of view.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01582876
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  • 187
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    Digitale Medien
    Application of sequential quadratic programming software program to an actual problem (1991)
    Springer
    Mathematical programming 52 (1991), S. 19-27 
    Details
    ISSN: 1436-4646
    Schlagwort(e): Nonlinear optimization ; sequential quadratic programming ; quadratic programming ; line search
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract We produced a nonlinear optimization software program which is based on a Sequential Quadratic Programming (SQP) method (Schittkowski, 1981a). Our program has several original characteristics: (1) automatic choice between two QP solvers, the Goldfarb—Idnani (GI) method (Goldfarb and Idnani, 1983) and the Least Squares (LS) method (Schittkowski, 1981b); (2) an augmented Lagrange function (Schittkowski, 1981a) as the objective function for line search; (3) adaptive Armijo method for line search; (4) direct definition of upper and lower bounds for variables and constraint functions; and (5) accurate numerical differentials. These characteristics ensure the reliability of our program for solving standard problems. In this paper, point (3) is described in detail. Then, the program is applied to an actual problem, the optimal placement of blocks. A model for this problem has been suggested by Sha and Dutton (1984), but it was unsuited to treatment by the SQP method. Thus we modify it to ensure program applicability.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01582877
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  • 188
    Digitale Medien
    Digitale Medien
    Uneven distribution of ventilation—perfusion ratios in lungs estimated by a modified Newton method (1991)
    Springer
    Mathematical programming 52 (1991), S. 1-9 
    Details
    ISSN: 1436-4646
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract The uneven distribution of ventilation—perfusion ratios ( $$\dot V_A /\dot Q$$ ) in diseased lungs is the major cause of arterial hypoxemia. Farhi and Yokoyama (1967) and Yokoyama and Farhi (1967) were the first who used physiologically inert gases as indicator gases to assess the uneven distribution of $$\dot V_A /\dot Q$$ Wagner and his coworkers in San Diego (1977b) extended the method and elaborated the multiple inert gas elimination technique in which blood flows in 50 compartments with different $$\dot V_A /\dot Q$$ were estimated based on data for 6 indicator gases. They analyzed the indicator gas data through an enforced smoothing technique with the ridge regression. To get smooth distributions, they introduced a weighting function for $$\dot V_A /\dot Q$$ compartments and an additional treatment for the non-negativity of the blood flow. The weighting function was empirically obtained. We analyzed the data without putting any weights on $$\dot V_A /\dot Q$$ compartments nor any additional treatment for non-negativity of blood flow. The analytical method in the present study was a modified Newton method, which is one of the enforced smoothing method. Our method was capable of recovering all distribution patterns that were found through the method reported by Wagner et al. (1977b).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01582875
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  • 189
    Digitale Medien
    Digitale Medien
    Optimization of pipe networks (1991)
    Springer
    Mathematical programming 52 (1991), S. 45-58 
    Details
    ISSN: 1436-4646
    Schlagwort(e): Gas and water distribution networks ; sequential linear programming ; trust regions ; sparse matrix techniques
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract The paper treats a piping system, where the layout of the network is given but the diameters of the pipes should be chosen among a small number of different values. The cost of realizing the system should be minimized while keeping the energy heads at the nodes above some lower limits. A new algorithm using successive linear programming is presented. The performance of the algorithm is illustrated by optimizing a network with 201 pipes and 172 nodes. It is concluded that the new algorithm seems to be very efficient and stable, and that it always finds a solution with a cost near the best possible.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01582879
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  • 190
    Digitale Medien
    Digitale Medien
    Approximate formulas of average distances associated with regions and their applications to location problems (1991)
    Springer
    Mathematical programming 52 (1991), S. 99-123 
    Details
    ISSN: 1436-4646
    Schlagwort(e): Location problem ; average distance
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract This study is concerned with the problem of measuring average distances between two points in two different coplanar regions. The objectives are: (1) to derive the approximated average distances associated with circular regions and to check their accuracy; and (2) to apply these approximated distances to location problems. Results show that the simple approximate formulas are accurate and useful. The approximated average distances can be applied to the analyses of varied kinds of movement phenomena in cities.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01582882
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  • 191
    Digitale Medien
    Digitale Medien
    Utilization of mathematical programming for public systems: An application to effective formation of integrated regional information networks (1991)
    Springer
    Mathematical programming 52 (1991), S. 71-98 
    Details
    ISSN: 1436-4646
    Schlagwort(e): Multiobjective approach ; group decision making ; regional utility function ; game theory ; nucleolus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract This paper concerns a methodological reflection on the multiobjective approach to public systems which involve group decision processes. Particular attention is given to an integrated program of regional systems which include value trade-offs between multiple objectives. Our intention is to combine the judgmental processes with the optimization processes in the “soft” public systems. A two-layer approach is applied. At the first layer, each regional program is formulated in mathematical programming based on a utility assessment with different regional characteristics. Each subsystem independently reflects its particular concern as a single agent. The dual optimal solutions obtained for each subsystem are treated as an index, or the theoretical prices, representing the value trade-offs among the multiple objectives. At the second layer, an effective formation of interregional cooperation for compromising the conflicting regional interests is examined. Ann-person cooperative game in the characteristic function form is used to evaluate the effectiveness of the cooperation. The characteristic function for the game is derived on the incremental value of the regional benefit after the formation of a cooperation. The nucleolus and the augmented nucleolus as the solution concepts of the cooperative game are used for indicating the effectiveness of the cooperation. Finally using alternative criteria, the results in assessing the best decisions are examined comparatively.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01582881
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  • 192
    Digitale Medien
    Digitale Medien
    On area-efficient drawings of rectangular duals for VLSI floor-plan (1991)
    Springer
    Mathematical programming 52 (1991), S. 29-43 
    Details
    ISSN: 1436-4646
    Schlagwort(e): VLSI-CAD ; floor-plan ; rectangular dual ; drawing of a rectangular dual ; lower bound estimation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract In this paper, we consider a problem to seek a rectangular dual $$\tilde D$$ and its area-efficient drawing such that $$\tilde D$$ can be drawn in the smallest area among all rectangular duals under the constraints imposed not only on the area and the minimum dimension of each face but also on the length of abutment between two adjacent faces. Since the problem is hard to solve, we tackle this problem in an exhaustive manner by using an algorithm to enumerate all the rectangular duals. In order to make this exhaustive method efficient, we propose the following two algorithms working under the constraints stated above; an algorithm to find an area-efficient drawing of a given rectangular dual, and an algorithm to estimate a lower bound to the area required to draw a given rectangular dual. We also show some esperimental results to demonstrate the effectiveness of the lower bound. The area-efficient drawing of $$\tilde D$$ can be used as a VLSI floor-plan by regarding each inner face of $$\tilde D$$ as an area for a block to be placed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01582878
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  • 193
    Digitale Medien
    Digitale Medien
    Exact penalty functions in proximal bundle methods for constrained convex nondifferentiable minimization (1991)
    Springer
    Mathematical programming 52 (1991), S. 285-302 
    Details
    ISSN: 1436-4646
    Schlagwort(e): Nondifferentiable minimization ; convex programming ; exact penalty functions ; numerical methods ; descent methods ; proximal bundle methods ; Primary 65K05 ; Secondary 90C25
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract This paper presents new versions of proximal bundle methods for solving convex constrained nondifferentiable minimization problems. The methods employϑ 1 orϑ ∞ exact penalty functions with new penalty updates that limit unnecessary penalty growth. In contrast to other methods, some of them are insensitive to problem function scaling. Global convergence of the methods is established, as well as finite termination for polyhedral problems. Some encouraging numerical experience is reported. The ideas presented may also be used in variable metric methods for smooth nonlinear programming.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01582892
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  • 194
    Digitale Medien
    Digitale Medien
    Lagrangean decomposition for integer nonlinear programming with linear constraints (1991)
    Springer
    Mathematical programming 52 (1991), S. 303-313 
    Details
    ISSN: 1436-4646
    Schlagwort(e): Integer nonlinear programming ; Lagrangean decomposition ; Lagrangean relaxation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract We present a Lagrangean decomposition to study integer nonlinear programming problems. Solving the dual Lagrangean relaxation we have to obtain at each iteration the solution of a nonlinear programming with continuous variables and an integer linear programming. Decreasing iteratively the primal—dual gap we propose two algorithms to treat the integer nonlinear programming.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01582893
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  • 195
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    Digitale Medien
    An analytical comparison of different formulations of the travelling salesman problem (1991)
    Springer
    Mathematical programming 52 (1991), S. 315-357 
    Details
    ISSN: 1436-4646
    Schlagwort(e): Travelling salesman problem ; problem formulations ; convex polyhedral cones ; polyhedra ; affine transformations
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract A transformation technique is proposed that permits one to derive the linear description of the imageX of a polyhedronZ under an affine linear transformation from the (given) linear description ofZ. This result is used to analytically compare various formulations of the asymmetric travelling salesman problem to the standard formulation due to Dantzig, Fulkerson and Johnson which are all shown to be “weaker formulations” in a precise setting. We also apply this transformation technique to “symmetrize” formulations and show, in particular, that the symmetrization of the standard asymmetric formulation results into the standard one for the symmetric version of the travelling salesman problem.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01582894
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  • 196
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    Digitale Medien
    Comparative analysis of affine scaling algorithms based on simplifying assumptions (1991)
    Springer
    Mathematical programming 52 (1991), S. 405-414 
    Details
    ISSN: 1436-4646
    Schlagwort(e): Linear programming ; primal and dual ; potential reduction algorithm ; affine scaling algorithm
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract We analyze several affine potential reduction algorithms for linear programming based on simplifying assumptions. We show that, under a strong probabilistic assumption regarding the distribution of the data in an iteration, the decrease in the primal potential function will be $$\Omega (\rho /\sqrt {log(n)} )$$ with high probability, compared to the guaranteedΩ(1). (ρ ⩾2n is a parameter in the potential function andn is the number of variables.) Under the same assumption, we further show that the objective reduction rate of Dikin's affine scaling algorithm is $$(1 - 1/\sqrt {log(n)} )$$ with high probability, compared to no guaranteed convergence rate.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01582897
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  • 197
    Digitale Medien
    Digitale Medien
    Global convergence of the affine scaling methods for degenerate linear programming problems (1991)
    Springer
    Mathematical programming 52 (1991), S. 377-404 
    Details
    ISSN: 1436-4646
    Schlagwort(e): Linear programming ; interior point methods ; affine scaling methods ; global analysis ; degenerate problems
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract In this paper we show the global convergence of the affine scaling methods without assuming any condition on degeneracy. The behavior of the method near degenerate faces is analyzed in detail on the basis of the equivalence between the affine scaling methods for homogeneous LP problems and Karmarkar's method. It is shown that the step-size 1/8, where the displacement vector is normalized with respect to the distance in the scaled space, is sufficient to guarantee the global convergence of the affine scaling methods.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01582896
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  • 198
    Digitale Medien
    Digitale Medien
    On lower bound updates in primal potential reduction methods for linear programming (1991)
    Springer
    Mathematical programming 52 (1991), S. 415-428 
    Details
    ISSN: 1436-4646
    Schlagwort(e): Interior point methods ; linear programming ; potential reduction methods ; Karmarkar's algorithm
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract We present a procedure for computing lower bounds for the optimal cost in a linear programming problem. Whenever the procedure succeeds, it finds a dual feasible slack and the associated duality gap. Although no projective transformations or problem restatements are used, the method coincides with the procedures by Todd and Burrell and by de Ghellinck and Vial when these procedures are applicable. The procedure applies directly to affine potential reduction algorithms, and improves on existent techniques for finding lower bounds.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01582898
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  • 199
    Digitale Medien
    Digitale Medien
    A combined phase I—phase II scaled potential algorithm for linear programming (1991)
    Springer
    Mathematical programming 52 (1991), S. 429-439 
    Details
    ISSN: 1436-4646
    Schlagwort(e): Linear programming ; potential function ; phase I ; phase II ; artificial variable
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract We develop an extension of the affinely scaled potential reduction algorithm which simultaneously obtains feasibility and optimality in a standard form linear program, without the addition of any “M” terms. The method, and its lower-bounding procedure, are particularly simple compared with previous interior algorithms not requiring feasibility.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01582899
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  • 200
    Digitale Medien
    Digitale Medien
    On the complexity of following the central path of linear programs by linear extrapolation II (1991)
    Springer
    Mathematical programming 52 (1991), S. 527-553 
    Details
    ISSN: 1436-4646
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract A class of algorithms is proposed for solving linear programming problems (withm inequality constraints) by following the central path using linear extrapolation with a special adaptive choice of steplengths. The latter is based on explicit results concerning the convergence behaviour of Newton's method to compute points on the central pathx(r), r〉0, and this allows to estimate the complexity, i.e. the total numberN = N(R, δ) of steps needed to go from an initial pointx(R) to a final pointx(δ), R〉δ〉0, by an integral of the local “weighted curvature” of the (primal—dual) path. Here, the central curve is parametrized with the logarithmic penalty parameterr↓0. It is shown that for large classes of problems the complexity integral, i.e. the number of stepsN, is not greater than constm α log(R/δ), whereα 〈 1/2 e.g.α = 1/4 orα = 3/8 (note thatα = 1/2 gives the complexity of zero order methods). We also provide a lower bound for the complexity showing that for some problems the above estimation can hold only forα ⩾ 1/3. As a byproduct, many analytical and structural properties of the primal—dual central path are obtained: there are, for instance, close relations between the weighted curvature and the logarithmic derivatives of the slack variables; the dependence of these quantities on the parameterr is described. Also, related results hold for a family of weighted trajectories, into which the central path can be embedded.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01582904
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