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  • 1
    Digitale Medien
    Digitale Medien
    On the stability of wavelet and Gabor frames (Riesz bases) (1999)
    Springer
    The journal of Fourier analysis and applications 5 (1999), S. 105-125 
    Details
    ISSN: 1531-5851
    Schlagwort(e): 26B05 ; 42B10 ; 42C99 ; frame ; Gabor system ; Riesz basis ; stability ; wavelet
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract If the sequence of functions ϕj, k is a wavelet frame (Riesz basis) or Gabor frame (Riesz basis), we obtain its perturbation system ψj,k which is still a frame (Riesz basis) under very mild conditions. For example, we do not need to know that the support of ϕ or ψ $$(\hat \phi or\hat \psi )$$ is compact as in [14]. We also discuss the stability of irregular sampling problems. In order to arrive at some of our results, we set up a general multivariate version of Littlewood-Paley type inequality which was originally considered by Lemarié and Meyer [17], then by Chui and Shi [9], and Long [16].
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01274192
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  • 2
    Digitale Medien
    Digitale Medien
    Reachability of locational Nash equilibria (1998)
    Springer
    OR spectrum 20 (1998), S. 101-107 
    Details
    ISSN: 1436-6304
    Schlagwort(e): Competitive location model ; Nash equilibria ; stability ; reachability ; Wettbewerbsmodelle in der Standorttheorie ; Nash Gleichgewicht ; Stabilität ; Erreichbarkeit
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung In der Arbeit werden die Standorte von Duopolisten in einem Baum untersucht. Unter der Annahme festgesetzter Preise werden notwendige und hinreichende Bedingungen für Nash Gleichgewichte für Standorte auf Bäumen hergeleitet. Unter Verwendung dieser Bedingungen wird dann gezeigt, daß — angenommen Nash Gleichgewichte existieren — diese in einem wiederholt angewandten sequentiellen Standortfindungsprozeß, in dem beide Duopolisten als Zielfunktion kurzfristige Gewinnmaximierung haben, auch erreicht werden.
    Notizen: Abstract This paper examines the location of duopolists on a tree. Given parametric prices, we first delineate necessary and sufficient conditions for locational Nash equilibria on trees. Given these conditions, we then show that Nash equilibria, provided they exist, can be reached in a repeated sequential relocation process in which both facilities follow short-term profit maximization objectives.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01539861
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  • 3
    Digitale Medien
    Digitale Medien
    Reachability of locational Nash equilibria (1998)
    Springer
    OR spectrum 20 (1998), S. 101-107 
    Details
    ISSN: 1436-6304
    Schlagwort(e): Key words: Competitive location model ; Nash equilibria ; stability ; reachability ; Schlüsselwörter: Wettbewerbsmodelle in der Standorttheorie ; Nash Gleichgewicht ; Stabilität ; Erreichbarkeit
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung. In der Arbeit werden die Standorte von Duopolisten in einem Baum untersucht. Unter der Annahme festgesetzter Preise werden notwendige und hinreichende Bedingungen für Nash Gleichgewichte für Standorte auf Bäumen hergeleitet. Unter Verwendung dieser Bedingungen wird dann gezeigt, daß– angenommen Nash Gleichgewichte existieren – diese in einem wiederholt angewandten sequentiellen Standortfindungsprozeß, in dem beide Duopolisten als Zielfunktion kurzfristige Gewinnmaximierung haben, auch erreicht werden. “Equilibrium is a place in heaven, but how do we get there from here?”
    Notizen: Abstract. This paper examines the location of duopolists on a tree. Given parametric prices, we first delineate necessary and sufficient conditions for locational Nash equilibria on trees. Given these conditions, we then show that Nash equilibria, provided they exist, can be reached in a repeated sequential relocation process in which both facilities follow short-term profit maximization objectives.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002910050058
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  • 4
    Digitale Medien
    Digitale Medien
    Money demand stability: Evidence from Spain (1998)
    Springer
    Empirical economics 23 (1998), S. 387-400 
    Details
    ISSN: 1435-8921
    Schlagwort(e): Key words: Money demand ; cointegration ; stability ; regime shift ; JEL classification: E41 ; C22
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Wirtschaftswissenschaften
    Notizen: Abstract. Using several tests for structural stability in regressions with I(1) variables and for the existence of cointegration in models with regime shifts, the empirical evidence on the existence of a structural break in the Spanish long-run demand for broad money (ALP2) is analysed.  The results indicate that shifts affecting the demand for ALP2 in recent years have substantially altered its long-run properties. As to the cause of this structural break, emphasis is placed on the role played by the increasing openness of the Spanish financial system to international markets as obstacles to free capital movements have progressively disappeared.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001810050027
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  • 5
    Digitale Medien
    Digitale Medien
    Discrete stability of the Differential System Method evaluated with geostatistical techniques (1998)
    Springer
    Stochastic environmental research and risk assessment 12 (1998), S. 191-204 
    Details
    ISSN: 1436-3259
    Schlagwort(e): Keywords: groundwater flow ; inverse problems ; stability ; geostatistical interpolation ; kriging.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung , Energietechnik , Geographie , Geologie und Paläontologie
    Notizen: Abstract The Differential System Method (DSM) permits identification of the physical parameters of finite-difference groundwater flow models in a confined aquifer when piezometric head and source terms are known at each point of the finite-difference lattice for at least two independent flow situations for which the hydraulic gradients are not parallel. Since piezometric head data are usually few and sparse, interpolation of the measured data onto a regular grid can be performed with geostatistical techniques. We apply kriging to the sparse data of a synthetic aquifer to evaluate the stability of the DSM with respect to uncorrelated measurement errors and interpolation errors. The numerical results show that the DSM is stable.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s004770050017
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  • 6
    Digitale Medien
    Digitale Medien
    Selektive Partnerwahl der Aaskrähe (Corvus corone) in der Hybridisierungszone von Rabenkrähe (C. c. corone) und Nebelkrähe (C. c. cornix) (1998)
    Springer
    Journal of ornithology 139 (1998), S. 173-177 
    Details
    ISSN: 1439-0361
    Schlagwort(e): mate choice ; taxonomy ; phenotypic hybrids ; fitness ; decision rule
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Die als Unterarten klassifizierten europäischen Formen der Aaskrähe, Rabenkrähe und Nebelkrähe, besiedeln verschiedene, aneinandergrenzende Verbreitungsgebiete und hybridisieren in der Kontaktzone. Die Nachkommen von Mischpaaren sind fruchtbar und können sowohl mit anderen Hybriden als auch mit Raben- und Nebelkrähen erfolgreich brüten. Trotzdem kommt es zu keiner völligen Vermischung der Formen und/oder Verlagerung der Verbreitungsgebiete. Vor diesem Hintergrund untersuchten wir die Partnerwahl von Aaskrähen in der Hybridisierungszone auf der nordfriesischen Insel Amrum und stellten fest, daß Partner gleichen Phänotyps häufiger miteinander verpaart waren, als stochastisch zu erwarten gewesen wäre. Unsere Daten bestätigen vergleichbare Studien aus Hybridisierungszonen in Italien und Sibirien. Wir schließen daraus, daß phänotypisch selektive Partnerwahl bei der Aaskrähe ein allgemeines Phänomen sein könnte und diskutieren, warum dieses Verhalten anfitness-relevante Parameter gekoppelt sein sollte. Um welche es sich dabei handeln könnte, wurde bisher nicht hinreichend untersucht und muß deshalb offen bleiben.
    Notizen: Summary Carrion Crow and Hooded Crow are regarded as subspecies of the Crow. They show frequent hybridisation along the adjacent borders of their distribution. Mixed pairs produce fertile offspring which are able to breed successfully with both hybrids and mates of either phenotype. However, hybridisation does not lead to phenotypic changes of Carrion and Hooded Crows in general nor in their distinct distribution. We studied the mating behaviour of Crows in the hybrid zone on the Island of Amrum (Schleswig-Holstein, Germany) and found evidence that Crows may prefer mates of the same phenotype. Our data confirm previous studies which reported assortative mating with respect to plumage coloration from hybrid zones in Italy and Siberia. We discuss why this behaviour should be related tofitness traits which in our opinion have not yet been studied adequately nor identified.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01651226
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  • 7
    Digitale Medien
    Digitale Medien
    A Two-Patch Model of Gambian Sleeping Sickness: Application to Vector Control Strategies in a Village and Plantations (1998)
    Springer
    Acta biotheoretica 46 (1998), S. 207-222 
    Details
    ISSN: 1572-8358
    Schlagwort(e): Epidemiology ; sleeping sickness ; vector controls ; differential equations ; spacialization ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A compartmental model is described for the spread of Gambian sleeping sickness in a spatially heterogeneous environment in which vector and human populations migrate between two "patches": the village and the plantations. The number of equilibrium points depends on two "summary parameters": gr the proportion removed among human infectives, and R0, the basic reproduction number. The origin is stable for R0 〈1 and unstable for R0 〉1. Control strategies are assessed by studying the mix of vector control between the two patches that bring R0 below 1. The results demonstrate the importance of vector control in the plantations. For example if 20 percent of flies are in the village and the blood meal rate in the village is 10 percent, then a 20 percent added vector mortality in the village must be combined with a 9 percent added mortality in the plantations in order to bring R0 below 1. The results are quite insentive to the blood meal rate in the village. Optimal strategies (that minimize the total number of flies trapped in both patches) are briefly discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1001776926167
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  • 8
    Digitale Medien
    Digitale Medien
    Stability and Instability of Fourth-Order Solitary Waves (1998)
    Springer
    Journal of dynamics and differential equations 10 (1998), S. 151-188 
    Details
    ISSN: 1572-9222
    Schlagwort(e): Fourth-order solitary waves ; stability ; instability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract We study ground-state traveling wave solutions of a fourth-order wave equation. We find conditions on the speed of the waves which imply stability and instability of the solitary waves. The analysis depends on the variational characterization of the ground states rather than information about the linearized operator.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1022644629950
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  • 9
    Digitale Medien
    Digitale Medien
    Stability of Semilinear Delay Equations with Positive Solutions (1997)
    Springer
    Positivity 1 (1997), S. 319-330 
    Details
    ISSN: 1572-9281
    Schlagwort(e): delay equations ; stability ; positive solutions ; spectral growth condition
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract We prove stability for a semilinear delay equation, whose nonlinearity is majorized by a linear positive operator. The key ingredients are a spectral condition, positivity of solutions to the linear problem, and lattice properties of the Banach space.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1009725823213
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  • 10
    Digitale Medien
    Digitale Medien
    Some Results on Stability of Retarded Functional Differential Equations Using Dichotomic Map Techniques (1998)
    Springer
    Positivity 2 (1998), S. 229-238 
    Details
    ISSN: 1572-9281
    Schlagwort(e): asymptotic stability ; dichotomic maps ; retarded functional differential equation ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract This paper deals with the study of the stability of nonautonomous retarded functional differential equations using the theory of dichotomic maps. After some preliminaries, we prove the theorems on simple and asymptotic stability. Some examples are given to illustrate the application of the method. Main results about asymptotic stability of the equation $$x'(t) = - b(t)x(t - r)$$ and of itsnonlinear generalization $$x'(t) = b(t)f(x(t - r))$$ are established.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1009742807025
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  • 11
    Digitale Medien
    Digitale Medien
    A Taxonomy of Evolutionary Algorithms in Combinatorial Optimization (1999)
    Springer
    Journal of heuristics 5 (1999), S. 145-158 
    Details
    ISSN: 1572-9397
    Schlagwort(e): evolutionary algorithms ; genetic algorithms ; taxonomy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract This paper shows how evolutionary algorithms can be described in a concise, yet comprehensive and accurate way. A classification scheme is introduced and presented in a tabular form called TEA (Table of Evolutionary Algorithms). It distinguishes between different classes of evolutionary algorithms (e.g., genetic algorithms, ant systems) by enumerating the fundamental ingredients of each of these algorithms. At the end, possible uses of the TEA are illustrated on classical evolutionary algorithms.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1009625526657
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  • 12
    Digitale Medien
    Digitale Medien
    On the stability of a partially accessible multi‐station queue with state‐dependent routing (1998)
    Springer
    Queueing systems 29 (1998), S. 55-73 
    Details
    ISSN: 1572-9443
    Schlagwort(e): multi‐server queue ; customer class ; state‐dependent routing ; stability ; Markov chain ; fluid limit
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik
    Notizen: Abstract We consider a multi‐station queue with a multi‐class input process when any station is available for the service of only some (not all) customer classes. Upon arrival, any customer may choose one of its accessible stations according to some state‐dependent policy. We obtain simple stability criteria for this model in two particular cases when service rates are either station‐ or class‐independent. Then, we study a two‐station queue under general assumptions on service rates. Our proofs are based on the fluid approximation approach.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1019175812444
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  • 13
    Digitale Medien
    Digitale Medien
    A stability criterion via fluid limits and its application to a polling system (1999)
    Springer
    Queueing systems 32 (1999), S. 131-168 
    Details
    ISSN: 1572-9443
    Schlagwort(e): stability ; positive recurrence ; fluid limit ; polling system ; exhaustive service policy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik
    Notizen: Abstract We introduce a generalized criterion for the stability of Markovian queueing systems in terms of stochastic fluid limits. We consider an example in which this criterion may be applied: a polling system with two stations and two heterogeneous servers.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1019187004209
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  • 14
    Digitale Medien
    Digitale Medien
    Stability of relative equilibria in arbitrary axisymmetric gravitational and magnetic fields (1999)
    Springer
    Celestial mechanics and dynamical astronomy 74 (1999), S. 19-57 
    Details
    ISSN: 1572-9478
    Schlagwort(e): stability ; Hamiltonian ; two centers ; oblate planet ; galactic disks ; dipole
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Relative equilibria occur in a wide variety of physical applications, including celestial mechanics, particle accelerators, plasma physics, and atomic physics. We derive sufficient conditions for Lyapunov stability of circular orbits in arbitrary axisymmetric gravitational (electrostatic) and magnetic fields, including the effects of local mass (charge) and current density. Particularly simple stability conditions are derived for source‐free regions, where the gravitational field is harmonic (∇2U = 0) or the magnetic field irrotational (∇ × B = 0). In either case the resulting stability conditions can be expressed geometrically (coordinate‐free) in terms of dimensionless stability indices. Stability bounds are calculated for several examples, including the problem of two fixed centers, the J2 planetary model, galactic disks, and a toroidal quadrupole magnetic field.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1008388105585
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  • 15
    Digitale Medien
    Digitale Medien
    Unrestricted Planar Problem of a Symmetric Body and a Point Mass. Triangular Libration Points and Their Stability (1999)
    Springer
    Celestial mechanics and dynamical astronomy 75 (1999), S. 251-285 
    Details
    ISSN: 1572-9478
    Schlagwort(e): unrestricted problem ; rotational motion ; rigid body dynamics ; libration points ; stability ; resonances
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract We present an analysis of the model introduced by Kokoriev and Kirpichnikov (1988) for the study of unrestricted planar motion of a point mass and a symmetric rigid body whose gravity field is approximated by two point masses (a dumb-bell model). To show possible generalization of the model, we give a systematic derivation of equations of motion for a more general unrestricted problem of a point and a rigid body possessing a plane of dynamical symmetry. We give a simple description of bifurcation of triangular libration points, and we perform an analysis of their linear stability. We propose to extend the model of Kokoriev and Kirpichnikov (1988) to a case when the symmetric body is oblate. In the proposed model the gravity field of moving and rotating body is approximated by two complex masses at complex distance (a complex dumb-bell model). An analysis of bifurcation of the triangular libration points in this model is also presented.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1008337017789
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  • 16
    Digitale Medien
    Digitale Medien
    Stability-Like Properties of Differential Inclusions (1997)
    Springer
    Set-valued analysis 5 (1997), S. 73-88 
    Details
    ISSN: 1572-932X
    Schlagwort(e): differential inclusion ; invariance ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract The properties of invariance, stability, asymptotic stability and attainability of a given compact set $$K \subset \mathbb{R}^n $$ with respect to a differential inclusion, have weak and strong versions: the weak version requires existence of a trajectory with the corresponding property, while the strong one requires this property for all trajectories. The following statement is proven in the paper (under slight restrictions) for each of the above-mentioned properties: if K has the weak property with respect to $$\dot x \in F(x) $$ , then there is a (regulation) mapping G such that G(x) ⊂ F(x) ∀ x and G has the strong property with respect to $${\dot x}$$ ε G(x). In addition, certain regularity of the set of solutions of the last inclusion is claimed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1008683223676
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  • 17
    Digitale Medien
    Digitale Medien
    Optimization and Stability Results Through Cone Lower Semicontinuity (1997)
    Springer
    Set-valued analysis 5 (1997), S. 365-375 
    Details
    ISSN: 1572-932X
    Schlagwort(e): set-valued mappings ; vector optimization ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract We establish optimization results for set-valued mappings, with the image space given by a topological vector space partially ordered by a cone. Moreover, we obtain stability results relative to parametrized optimization problems. We use a weak semicontinuity concept related to the order structure of the image space and show how compactness assumptions used in previous papers can be lightened.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1008653120360
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  • 18
    Digitale Medien
    Digitale Medien
    The Stability of Self-Organized Rule-Following Work Teams (1999)
    Springer
    Computational & mathematical organization theory 5 (1999), S. 5-30 
    Details
    ISSN: 1572-9346
    Schlagwort(e): network models ; organization theory ; rule following ; self organized ; stability ; work teams ; work routine
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract Self-organized rule-following systems are increasingly relevant objects of study in organization theory due to such systems&2018; capacity to maintain control while enabling decentralization of authority. This paper proposes a network model for such systems and examines the stability of the networks&2018; repetitive behavior. The networks examined are Ashby nets, a fundamental class of binary systems: connected aggregates of nodes that individually compute an interaction rule, a binary function of their three inputs. The nodes, which we interpret as workers in a work team, have two network inputs and one self-input. All workers in a given team follow the same interaction rule. We operationalize the notion of stability of the team&2018;s work routine and determine stability under small perturbations for all possible rules these teams can follow. To study the organizational concomitants of stability, we characterize the rules by their memory, fluency, homogeneity, and autonomy. We relate these measures to work routine stability, and find that stability in ten member teams is enhanced by rules that have low memory, high homogeneity, and low autonomy.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1009689326098
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  • 19
    Digitale Medien
    Digitale Medien
    Piecewise linear test functions for stability and instability of queueing networks (1997)
    Springer
    Queueing systems 27 (1997), S. 205-226 
    Details
    ISSN: 1572-9443
    Schlagwort(e): multiclass queueing networks ; ergodicity ; stability ; performance analysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik
    Notizen: Abstract We develop the use of piecewise linear test functions for the analysis of stability of multiclass queueing networks and their associated fluid limit models. It is found that if an associated LP admits a positive solution, then a Lyapunov function exists. This implies that the fluid limit model is stable and hence that the network model is positive Harris recurrent with a finite polynomial moment. Also, it is found that if a particular LP admits a solution, then the network model is transient.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1019166115653
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  • 20
    Digitale Medien
    Digitale Medien
    On the guaranteed throughput and efficiency of closed re-entrant lines (1998)
    Springer
    Queueing systems 28 (1998), S. 33-54 
    Details
    ISSN: 1572-9443
    Schlagwort(e): queueing networks ; throughput ; closed networks ; efficiency ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik
    Notizen: Abstract A closed network is said to be “guaranteed efficient” if the throughput converges under all non-idling policies to the capacity of the bottlenecks in the network, as the number of trapped customers increases to infinity. We obtain a necessary condition for guaranteed efficiency of closed re-entrant lines. For balanced two-station systems, this necessary condition is almost sufficient, differing from it only by the strictness of an inequality. This near characterization is obtained by studying a special type of virtual station called “alternating visit virtual station”. These special virtual stations allow us to relate the necessary condition to certain indices arising in heavy traffic studies using a Brownian network approximation, as well as to certain policies proposed as being extremal with respect to the asymptotic loss in the throughput. Using the near characterization of guaranteed efficiency we also answer the often pondered question of whether an open network or its closed counterpart has greater throughput - the answer is that neither can assure a greater guaranteed throughput.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1019199022922
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  • 21
    Digitale Medien
    Digitale Medien
    Stability of a three‐station fluid network (1999)
    Springer
    Queueing systems 33 (1999), S. 293-325 
    Details
    ISSN: 1572-9443
    Schlagwort(e): stability ; fluid models ; multiclass queueing networks ; piecewise linear Lyapunov functions ; linear Lyapunov functions ; monotone global stability ; static buffer priority disciplines
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik
    Notizen: Abstract This paper studies the stability of a three‐station fluid network. We show that, unlike the two‐station networks in Dai and Vande Vate [18], the global stability region of our three‐station network is not the intersection of its stability regions under static buffer priority disciplines. Thus, the “worst” or extremal disciplines are not static buffer priority disciplines. We also prove that the global stability region of our three‐station network is not monotone in the service times and so, we may move a service time vector out of the global stability region by reducing the service time for a class. We introduce the monotone global stability region and show that a linear program (LP) related to a piecewise linear Lyapunov function characterizes this largest monotone subset of the global stability region for our three‐station network. We also show that the LP proposed by Bertsimas et al. [1] does not characterize either the global stability region or even the monotone global stability region of our three‐station network. Further, we demonstrate that the LP related to the linear Lyapunov function proposed by Chen and Zhang [11] does not characterize the stability region of our three‐station network under a static buffer priority discipline.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1019184331042
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  • 22
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    Digitale Medien
    Discrete time semigroup transformations with random perturbations (1997)
    Springer
    Journal of dynamics and differential equations 9 (1997), S. 463-505 
    Details
    ISSN: 1572-9222
    Schlagwort(e): Difference equations ; random perturbation ; averaging ; diffusion approximation ; randomly perturbed iterations ; stability ; 3SR60 ; 60H15 ; 60J99
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract Let (X, ℬ) and (Y,C) be two measurable spaces withX being a linear space. A system is determined by two functionsf(X): X→ X andϕ:X×Y→X, a (small) positive parameterε and a homogeneous Markov chain {y n } in (Y,C) which describes random perturbations. States of the system, say {x n ɛ ∈X, n=0, 1,⋯}, are determined by the iteration relations:x n+1 ɛ =f(x n ɛ )+ɛϕ(x n ɛ ,Yn+1) forn≥0, wherex 0 ɛ =x 0 is given. Here we study the asymptotic behavior of the solutionx n ɛ asε → 0 andn → ∞ under various assumptions on the data. General results are applied to some problems in epidemics, genetics and demographics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02227491
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  • 23
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    Digitale Medien
    On Stability and Boundedness for Lipschitzian Differential Inclusions: The Converse of Lyapunov's Theorems (1997)
    Springer
    Set-valued analysis 5 (1997), S. 377-390 
    Details
    ISSN: 1572-932X
    Schlagwort(e): differential inclusions ; stability ; boundedness of solutions ; Lyapunov functions
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract For Lipschitzian differential inclusions, we prove that the existence of suitable Lyapunov functions is necessary for uniform stability and uniform boundedness of solutions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1008603707291
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  • 24
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    Digitale Medien
    Implicit Multifunction Theorems (1999)
    Springer
    Set-valued analysis 7 (1999), S. 209-238 
    Details
    ISSN: 1572-932X
    Schlagwort(e): nonsmooth analysis ; subdifferentials ; coderivatives ; implicit function theorem ; solvability ; stability ; open mapping theorem ; metric regularity ; multidirectional mean value inequality
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract We prove a general implicit function theorem for multifunctions with a metric estimate on the implicit multifunction and a characterization of its coderivative. Traditional open covering theorems, stability results, and sufficient conditions for a multifunction to be metrically regular or pseudo-Lipschitzian can be deduced from this implicit function theorem. We prove this implicit multifunction theorem by reducing it to an implicit function/solvability theorem for functions. This approach can also be used to prove the Robinson–Ursescu open mapping theorem. As a tool for this alternative proof of the Robinson–Ursescu theorem, we also establish a refined version of the multidirectional mean value inequality which is of independent interest.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1008775413250
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  • 25
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    Digitale Medien
    Stability and performance analysis of rate-based feedback flow controlled ATM networks (1998)
    Springer
    Queueing systems 29 (1998), S. 129-159 
    Details
    ISSN: 1572-9443
    Schlagwort(e): rate-based feedback control ; ATM networks ; stability ; optimal algorithms
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik
    Notizen: Abstract Motivated by ABR class of service in ATM networks, we study a continuous time queueing system with a feedback control of the arrival rate of some of the sources. The feedback about the queue length or the total workload is provided at regular intervals (variations on it, especially the traffic management specification TM 4.0, are also considered). The propagation delays can be nonnegligible. For a general class of feedback algorithms, we obtain the stability of the system in the presence of one or more bottleneck nodes in the virtual circuit. Our system is general enough that it can be useful to study feedback control in other network protocols. We also obtain rates of convergence to the stationary distributions and finiteness of moments. For the single botterneck case, we provide algorithms to compute the stationary distributions and the moments of the sojourn times in different sets of states. We also show analytically (by showing continuity of stationary distributions and moments) that for small propagation delays, we can provide feedback algorithms which have higher mean throughput, lower probability of overflow and lower delay jitter than any open loop policy. Finally these results are supplemented by some computational results.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1019127929282
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  • 26
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    Digitale Medien
    Dynamic scheduling in multiclass queueing networks: Stability under discrete-review policies (1999)
    Springer
    Queueing systems 31 (1999), S. 171-206 
    Details
    ISSN: 1572-9443
    Schlagwort(e): scheduling ; open multiclass queueing networks ; discrete-review policies ; fluid models ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik
    Notizen: Abstract This paper describes a family of discrete-review policies for scheduling open multiclass queueing networks. Each of the policies in the family is derived from what we call a dynamic reward function: such a function associates with each queue length vector q and each job class k a positive value r k (q), which is treated as a reward rate for time devoted to processing class k jobs. Assuming that each station has a traffic intensity parameter less than one, all policies in the family considered are shown to be stable. In such a policy, system status is reviewed at discrete points in time, and at each such point the controller formulates a processing plan for the next review period, based on the queue length vector observed. Stability is proved by combining elementary large deviations theory with an analysis of an associated fluid control problem. These results are extended to systems with class dependent setup times as well as systems with alternate routing and admission control capabilities.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1019106213778
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  • 27
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    Digitale Medien
    On the stability of retrial queues (1997)
    Springer
    Queueing systems 26 (1997), S. 343-363 
    Details
    ISSN: 1572-9443
    Schlagwort(e): retrial queues ; stability ; ergodicity ; renovation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik
    Notizen: Abstract We consider the following Type of problems. Calls arrive at a queue of capacity K (which is called the primary queue), and attempt to get served by a single server. If upon arrival, the queue is full and the server is busy, the new arriving call moves into an infinite capacity orbit, from which it makes new attempts to reach the primary queue, until it finds it non-full (or it finds the server idle). If the queue is not full upon arrival, then the call (customer) waits in line, and will be served according to the FIFO order. If λ is the arrival rate (average number per time unit) of calls and μ is one over the expected service time in the facility, it is well known that μ 〉 λ is not always sufficient for stability. The aim of this paper is to provide general conditions under which it is a sufficient condition. In particular, (i) we derive conditions for Harris ergodicity and obtain bounds for the rate of convergence to the steady state and large deviations results, in the case that the inter-arrival times, retrial times and service times are independent i.i.d. sequences and the retrial times are exponentially distributed; (ii) we establish conditions for strong coupling convergence to a stationary regime when either service times are general stationary ergodic (no independence assumption), and inter-arrival and retrial times are i.i.d. exponentially distributed; or when inter-arrival times are general stationary ergodic, and service and retrial times are i.i.d. exponentially distributed; (iii) we obtain conditions for the existence of uniform exponential bounds of the queue length process under some rather broad conditions on the retrial process. We finally present conditions for boundedness in distribution for the case of nonpatient (or non persistent) customers.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1019193527040
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  • 28
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    Digitale Medien
    Recurrence and transience properties of some neural networks: an approach via fluid limit models (1999)
    Springer
    Queueing systems 32 (1999), S. 99-130 
    Details
    ISSN: 1572-9443
    Schlagwort(e): neural network ; inhibition ; stability ; Markov process ; fluid limit ; Harris-recurrence ; transience
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik
    Notizen: Abstract The subject of the paper is the stability analysis of some neural networks consisting of a finite number of interacting neurons. Following the approach of Dai [5] we use the fluid limit model of the network to derive a sufficient condition for positive Harris-recurrence of the associated Markov process. This improves the main result in Karpelevich et al. [11] and, at the same time, sheds some new light on it. We further derive two different conditions that are sufficient for transience of the state process and illustrate our results by classifying some examples according to positive recurrence or transience.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1019135020138
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  • 29
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    Digitale Medien
    Window flow control in FIFO networks with cross traffic (1999)
    Springer
    Queueing systems 32 (1999), S. 195-231 
    Details
    ISSN: 1572-9443
    Schlagwort(e): window flow control ; TCP ; stability ; multiclass networks ; stationary ergodic point processes ; (max,+)-linear system
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik
    Notizen: Abstract We focus on window flow control as used in packet-switched communication networks. The approach consists in studying the stability of a system where each node on the path followed by the packets of the controlled connection is modeled by a FIFO (First-In-First-Out) queue of infinite capacity which receives in addition some cross traffic represented by an exogenous flow. Under general stochastic assumptions, namely for stationary and ergodic input processes, we show the existence of a maximum throughput allowed by the flow control. Then we establish bounds on the value of this maximum throughput. These bounds, which do not coincide in general, are reached by time-space scalings of the exogenous flows. Therefore, the performance of the window flow control depends not only on the traffic intensity of the cross flows, but also on fine statistical characteristics such as the burstiness of these flows. These results are illustrated by several examples, including the case of a nonmonotone, nonconvex and fractal stability region.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1019191105117
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  • 30
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    Digitale Medien
    Numerical computation of stability and detection of Hopf bifurcations of steady state solutions of delay differential equations (1999)
    Springer
    Advances in computational mathematics 10 (1999), S. 271-289 
    Details
    ISSN: 1572-9044
    Schlagwort(e): delay differential equations ; steady state solutions ; stability ; 34K20 ; 65J10
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract The characteristic equation of a system of delay differential equations (DDEs) is a nonlinear equation with infinitely many zeros. The stability of a steady state solution of such a DDE system is determined by the number of zeros of this equation with positive real part. We present a numerical algorithm to compute the rightmost, i.e., stability determining, zeros of the characteristic equation. The algorithm is based on the application of subspace iteration on the time integration operator of the system or its variational equations. The computed zeros provide insight into the system’s behaviour, can be used for robust bifurcation detection and for efficient indirect calculation of bifurcation points.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1018986817622
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  • 31
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    Digitale Medien
    A New Approach to Backward Error Analysis of Lu Factorization (1999)
    Springer
    BIT 39 (1999), S. 385-402 
    Details
    ISSN: 1572-9125
    Schlagwort(e): Gaussian elimination ; stability ; backward error analysis ; growth factor
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract A new backward error analysis of LU factorization is presented. It allows to obtain a sharper upper bound for the forward error and a new definition of the growth factor that we compare with the well known Wilkinson growth factor for some classes of matrices. Numerical experiments show that the new growth factor is often of order approximately log2 n whereas Wilkinson's growth factor is of order n or $$\sqrt n$$ .
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1022358300517
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  • 32
    Digitale Medien
    Digitale Medien
    Multiwavelet approximation methods for pseudodifferential equations on curves. Stability and convergence analysis (1998)
    Springer
    Advances in computational mathematics 9 (1998), S. 145-171 
    Details
    ISSN: 1572-9044
    Schlagwort(e): periodic pseudodifferential equations ; multiwavelets ; splines with multiple knots ; generalized Galerkin–Petrov schemes ; boundary element methods ; error analysis ; stability ; Strang–Fix condition ; 65J10 ; 65N30 ; 65N35 ; 65R20 ; 47G30 ; 45P05 ; 41A25 ; 41A30 ; 41A15
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract We develop a stability and convergence analysis of Galerkin–Petrov schemes based on a general setting of multiresolution generated by several refinable functions for the numerical solution of pseudodifferential equations on smooth closed curves. Particular realizations of such a multiresolution analysis are trial spaces generated by biorthogonal wavelets or by splines with multiple knots. The main result presents necessary and sufficient conditions for the stability of the numerical method in terms of the principal symbol of the pseudodifferential operator and the Fourier transforms of the generating multiscaling functions as well as of the test functionals. Moreover, optimal convergence rates for the approximate solutions in a range of Sobolev spaces are established.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1018977120831
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  • 33
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    Digitale Medien
    Stability of Hypersurfaces with Constant $$r$$ -Mean Curvature (1997)
    Springer
    Annals of global analysis and geometry 15 (1997), S. 277-297 
    Details
    ISSN: 1572-9060
    Schlagwort(e): mean curvature ; $$r$$ -mean curvature ; sphere ; stability ; stable
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract We deal with compact hypersurfaces immersed in space forms with constant $$r$$ -mean curvature. They are critical points for a variational problem. We show they are stable if and only if they are geodesic spheres, generalizing results on constant curvature hypersurfaces.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1006514303828
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  • 34
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    Digitale Medien
    Stability Concepts in Topological Dynamics by Nonstandard Methods (1997)
    Springer
    Acta applicandae mathematicae 49 (1997), S. 35-54 
    Details
    ISSN: 1572-9036
    Schlagwort(e): dynamical systems ; stability ; pseudo orbit tracing property ; nonstandard analysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract It is known that it is not possible to introduce C0 -structural stability for whole systems in topological dynamics. Using the methods of Nonstandard Analysis, we suggest four different purely topological stability concepts for dynamical systems on compact subsets of Rn. Classically these amount to considering the space of all systems on a given subset of Rn as the fundamental entity when deforming a continuous system (instead of the space of all continuous systems as is normally done in topological dynamics). For two of the introduced stability concepts, we will show that all minimal flows are stable in this sense. Besides this, we will show that one of our stability concepts is related to what is called the pseudo orbit tracing property in a recently published book by Aoki and Hiraide and compare some of our results to the theory of dynamical systems as presented there.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1005840309425
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  • 35
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    Digitale Medien
    Stability and Geometry of Third-Order Resonances in four-Dimensional Symplectic Mappings (1997)
    Springer
    Celestial mechanics and dynamical astronomy 67 (1997), S. 181-204 
    Details
    ISSN: 1572-9478
    Schlagwort(e): Hamiltonian systems ; symplectic mappings ; normal forms ; resonances ; stability ; three degrees of freedom
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract We analyze four-dimensional symplectic mappings in the neighbourhood of an elliptic fixed point whose eigenvalues are close to satisfy a third-order resonance. Using the perturbative tools of resonant normal forms, the geometry of the orbits and the existence of elliptic or hyperbolic one-dimensional tori (fixed lines) is worked out. This allows one to give an analytical estimate of the stability domain when the resonance is unstable. A comparison with numerical results for the four-dimensional Hénon mapping is given.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1008288826727
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  • 36
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    Digitale Medien
    Runge–Kutta–Nyström‐type parallel block predictor–corrector methods (1999)
    Springer
    Advances in computational mathematics 10 (1999), S. 115-133 
    Details
    ISSN: 1572-9044
    Schlagwort(e): Runge–Kutta–Nyström methods ; predictor–corrector methods ; stability ; parallelism ; 65M12 ; 65M20
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract This paper describes the construction of block predictor–corrector methods based on Runge–Kutta–Nyström correctors. Our approach is to apply the predictor–corrector method not only with stepsize h, but, in addition (and simultaneously) with stepsizes a i h, i = 1 ...,r. In this way, at each step, a whole block of approximations to the exact solution at off‐step points is computed. In the next step, these approximations are used to obtain a high‐order predictor formula using Lagrange or Hermite interpolation. Since the block approximations at the off‐step points can be computed in parallel, the sequential costs of these block predictor–corrector methods are comparable with those of a conventional predictor–corrector method. Furthermore, by using Runge–Kutta–Nyström corrector methods, the computation of the approximation at each off‐step point is also highly parallel. Numerical comparisons on a shared memory computer show the efficiency of the methods for problems with expensive function evaluations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1018930732643
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  • 37
    Digitale Medien
    Digitale Medien
    Existence and Stability of L4,5 In The Relativistic Restricted Three-Body Problem (1997)
    Springer
    Celestial mechanics and dynamical astronomy 69 (1997), S. 271-281 
    Details
    ISSN: 1572-9478
    Schlagwort(e): restricted three-body problem ; libration points ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The existence and stability of triangular libration points in the relativistic restricted three-body problem has been studied. It is found that L4,5 are unstable in the whole range 0 ≤ µ ≤ 1/2 in contrast to the classical restricted three-body problem where they are stable for 0 〈 µ 〈 µ0, where µ is the mass parameter and µ0 = 0.03852....
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1008271021060
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  • 38
    Digitale Medien
    Digitale Medien
    Long Time Stability for the Main Problem of Artificial Satellites (1997)
    Springer
    Celestial mechanics and dynamical astronomy 69 (1997), S. 317-330 
    Details
    ISSN: 1572-9478
    Schlagwort(e): artificial satellite ; Nekhoroshev's theory ; normal form ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract We investigate the significance of long time stabilty predictions in the light of Nekhoroshev's theory by studying the orbits of artificial satellites. As a simplified model problem we consider the so-called J2problem for an earth's satellite, neglecting luni-solar perturbations and nonconservative effects. We consider a wide range of orbits, excluding those which are too close to the critical inclination. Most of the orbits turn out to be stable for times larger than the estimated age of the solar system, thus proving that, as far as dissipation can be neglected, stability in Nekhoroshev's sense may be effective for physically realistic systems.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1008277122375
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  • 39
    Digitale Medien
    Digitale Medien
    Nonlinear Stability of the Lagrangian Libration Points in the Chermnykh Problem (1998)
    Springer
    Celestial mechanics and dynamical astronomy 70 (1998), S. 41-58 
    Details
    ISSN: 1572-9478
    Schlagwort(e): three-body problem ; libration points ; stability ; normal forms.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract In this paper we consider the problem of motion of an infinitesimal point mass in the gravity field of an uniformly rotating dumb-bell. The aim of our study is to investigate Liapunov stability of Lagrangian libration points of this problem. We analyze the stability of libration points in the whole range of parameters ω, μ of the problem. In particular, we consider all resonance cases when the order of resonance is not greater than five.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1008250207046
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  • 40
    Digitale Medien
    Digitale Medien
    Exponential Integrators for Quantum-Classical Molecular Dynamics (1999)
    Springer
    BIT 39 (1999), S. 620-645 
    Details
    ISSN: 1572-9125
    Schlagwort(e): Numerical integrator ; oscillatory solutions ; Schrödinger equation ; quantum-classical coupling ; error bounds ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract We study time integration methods for equations of mixed quantum-classical molecular dynamics in which Newtonian equations of motion and Schrödinger equations are nonlinearly coupled. Such systems exhibit different time scales in the classical and the quantum evolution, and the solutions are typically highly oscillatory. The numerical methods use the exponential of the quantum Hamiltonian whose product with a state vector is approximated using Lanczos' method. This allows time steps that are much larger than the inverse of the highest frequencies. We describe various integration schemes and analyze their error behaviour, without assuming smoothness of the solution. As preparation and as a problem of independent interest, we study also integration methods for Schrödinger equations with time-dependent Hamiltonian.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1022335122807
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  • 41
    Digitale Medien
    Digitale Medien
    Three Dimensional Laser Simulation Code on a Desktop Personal Computer (1999)
    Springer
    Optical review 6 (1999), S. 28-36 
    Details
    ISSN: 1349-9432
    Schlagwort(e): optical propagation equation ; stability ; picosecond pulse ; 3-dimensional computation ; Fresnel’s distribution ; fast Fourier transform
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract We present a new simulation code able to simulate the entire propagation of laser pulse, from the amplifiers level up to the focusing stage. This algorithm has some new characteristics that we intend to present. It computes the three-dimensional optical propagation equation using no approximation other than its picosecond expression. The stability has been carefully studied so that it can be applied to any geometry. This is a great improvement since, up to now only cylindrical geometry was accessible for accuracy. In this paper we also present a method using Fast Fourier Transform able to evaluate with a high accuracy, Fresnel’s distribution of a focused laser pulse. The advantages provided by our algorithm are its rapidity and its high physical understanding of the focusing phenomena.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s10043-999-0028-1
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  • 42
    Digitale Medien
    Digitale Medien
    On a spherical integral transformation and sections of star bodies (1998)
    Springer
    Monatshefte für Mathematik 126 (1998), S. 117-124 
    Details
    ISSN: 1436-5081
    Schlagwort(e): 52A20 ; 52A22 ; star bodies ; spherical integral transformations ; convex bodies ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract LetK be ad-dimensional star body (with respect to the origino). It is known that the (d−1)-dimensional volume of the intersections ofK with the hyperplanes througho does not uniquely determineK. Uniqueness can only be achieved under additional assumptions, such as central symmetry. Here it is pointed out that if one uses, instead of intersections by hyperplanes, intersections by half-planes that containo on the boundary, then, without any additional assumptions, the volume of these intersections determinesK uniquely. This assertion, and more general results of this kind, together with stability estimates, are obtained from uniqueness results and estimates concerning a particular spherical integral transformation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01473582
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  • 43
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    Digitale Medien
    Ethene hydroformylation on Co/SiO2 catalysts (1998)
    Springer
    Catalysis letters 53 (1998), S. 97-101 
    Details
    ISSN: 1572-879X
    Schlagwort(e): ethene hydroformylation ; heterogeneous catalysts ; cobalt catalysts ; gas‐phase deposition ; dispersion ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The results from ethene hydroformylation at 173°C showed that a Co(acac)3/SiO2 catalyst prepared from Co(acac)3 precursor by gas‐phase deposition was three times as active as a catalyst prepared by impregnation from cobalt nitrate, but oxo‐selectivities were similar. The high propanal selectivities on the Co(acac)3/SiO2 seem to be related to the presence of highly dispersed active sites favouring CO insertion. As dispersion is decreased from 23 to 8% due to increasing metal content (from 5 to 16 wt%), oxo‐selectivity decreased from 39 to 25%. The activity of Co(acac)3/SiO2 remained unchanged during 68 h on stream. The gas‐phase deposition technique described here is a promising method for the preparation of active, selective and stable heterogeneous hydroformylation catalysts.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1019053805618
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  • 44
    Digitale Medien
    Digitale Medien
    Preparation of model catalysts by laser interference nanolithography followed by metal cluster deposition (1998)
    Springer
    Catalysis letters 56 (1998), S. 1-6 
    Details
    ISSN: 1572-879X
    Schlagwort(e): nanolithography ; model catalyst ; palladium ; copper ; stability ; spin-coating ; SEM ; AFM ; XPS
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Metal clusters arranged on nanostructured oxidized silicon wafers are presented as new model catalyst systems. A photoresist layer spun on top of a wafer was patterned by laser interference exposure. The grid obtained after removing the exposed parts of the resist is used as an etching mask. Hollows with diameters of 300 nm and depths between 50 and 60 nm were etched into the oxide layer using wet chemical methods. Two methods were applied to deposit metal clusters (Pd or Cu) in a defined way within the hollows. The particles ranged from 10 to 50 nm in height and from 80 to 200 nm in diameter. The model catalyst systems were characterized by atomic force microscopy and X-ray photoelectron spectroscopy. The method presented here allows us to produce 4 inch wafers that are covered completely by nanometer-sized structures in a reasonable period of time.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1019080222823
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  • 45
    Digitale Medien
    Digitale Medien
    On the rotating rod with variable cross section (1997)
    Springer
    Archive of applied mechanics 67 (1997), S. 447-456 
    Details
    ISSN: 1432-0681
    Schlagwort(e): Key words rotation ; stability ; energy criterion ; variational analysis ; functional analysis ; eigenvalue problem
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Summary Stability of a heavy rotating rod with a variable cross section is studied by energy method. Bifurcation points for the system of equilibrium equations are analyzed. It is shown that for the case when the rotation speed exceeds the critical one, the trivial solution ceases to be the minimizer of the potential energy, so that rod loses stability, according to the energy criteria. Also, a new estimate of the maximal rod deflection in the post-critical state is obtained.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s004190050130
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  • 46
    Digitale Medien
    Digitale Medien
    Global dynamical behavior of a three-body system with flexible connection in the gravitational field (1999)
    Springer
    Archive of applied mechanics 69 (1999), S. 47-54 
    Details
    ISSN: 1432-0681
    Schlagwort(e): Key words Bifurcation ; stability ; multibody system dynamics ; singularity theory ; Liapunov's direct method
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Summary In this paper, the global behavior of relative equilibrium states of a three-body satellite with flexible connection under the action of the gravitational torque is studied. With geometric method, the conditions of existence of nontrivial solutions to the relative equilibrium equations are determined. By using reduction method and singularity theory, the conditions of occurrence of bifurcation from trivial solutions are derived, which agree with the existence conditions of nontrivial solutions, and the bifurcation is proved to be pitchfork-bifurcation. The Liapunov stability of each equilibrium state is considered, and a stability diagram in terms of system parameters is presented.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s004190050203
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  • 47
    Digitale Medien
    Digitale Medien
    Autonomous Intelligent Cruise Control with Actuator Delays (1998)
    Springer
    Journal of intelligent and robotic systems 23 (1998), S. 27-43 
    Details
    ISSN: 1573-0409
    Schlagwort(e): autonomous control ; actuator delays ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Maschinenbau
    Notizen: Abstract In this paper, we consider the control design problem of vehicle following systems with actuator delays. An upper bound for the time delays is first constructed to guarantee the vehicle stability. Second, sufficient conditions are presented to avoid slinky-effects in the vehicle following. Next, zero steady state achieved by the proposed controller is proven. Finally, simulations are given to examine our claims.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1007946007601
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  • 48
    Digitale Medien
    Digitale Medien
    Sensitivity and Stability of the Classifications of Returns to Scale in Data Envelopment Analysis (1999)
    Springer
    Journal of productivity analysis 12 (1999), S. 55-75 
    Details
    ISSN: 1573-0441
    Schlagwort(e): Data envelopment analysis (DEA) ; returns to scale (RTS) ; sensitivity ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Wirtschaftswissenschaften
    Notizen: Abstract Sensitivity of the returns to scale (RTS) classifications in data envelopment analysis is studied by means of linear programming problems. The stability region for an observation preserving its current RTS classification (constant, increasing or decreasing returns to scale) can be easily investigated by the optimal values to a set of particular DEA-type formulations. Necessary and sufficient conditions are determined for preserving the RTS classifications when input or output data perturbations are non-proportional. It is shown that the sensitivity analysis method under proportional data perturbations can also be used to estimate the RTS classifications and discover the identical RTS regions yielded by the input-based and the output-based DEA methods. Thus, our approach provides information on both the RTS classifications and the stability of the classifications. This sensitivity analysis method can easily be applied via existing DEA codes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1007803207538
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  • 49
    Digitale Medien
    Digitale Medien
    Identity of Fusarium nygamai isolates with long and short microconidial chains from millet, sorghum and soil in Africa (1997)
    Springer
    Mycopathologia 140 (1997), S. 171-176 
    Details
    ISSN: 1573-0832
    Schlagwort(e): Africa ; Fusarium ; F. moniliforme ; grain ; Lesotho ; mating population ; Nigeria ; taxonomy ; Zimbabwe
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Several Fusarium species have been found associated with millet and sorghum in Nigeria, Lesotho and Zimbabwe. Amongst these, some isolates were originally identified as short- and long-chained types of F. nygamai. However, there was some question as to the correct identification of the long chained types. This study reclassified some of the isolates with long microconidial chains as F. moniliforme. Morphologically, these strains do not produce chlamydospores like F. nygamai, but produce swollen hyphal cells or resistant hyphae. The isolates in this study were crossed with the mating-type tester strains of Gibberella fujikuroi (F. moniliforme and G. nygamai (F. nygamai). Of the isolates with long chains of microconidia and other characteristics of F. moniliforme, 36% crossed with mating population ''A'' of G. fujikuroi. Of the isolates with characteristics of F. nygamai, 65% crossed with the testers used to produce the teleomorph of F. nygamai. Mating tests support the separation of the sample population into F. moniliforme and F. nygamai. The results of this study show that genetics can be an aid in resolving some problems in fungal taxonomy.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1006863825469
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  • 50
    Digitale Medien
    Digitale Medien
    Can the ecosystem mimic hypotheses be applied to farms in African savannahs? (1999)
    Springer
    Agroforestry systems 45 (1999), S. 131-158 
    Details
    ISSN: 1572-9680
    Schlagwort(e): competition ; fertility ; microclimate ; risk ; stability ; water
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract The first ecosystem mimic hypothesis suggests clear advantages if man-made land use systems do not deviate greatly in their resource use patterns from natural ecosystems typical of a given climatic zone. The second hypothesis claims that additional advantages will accrue if agroecosystems also maintain a substantial part of the diversity of natural systems. We test these hypotheses for the savannah zone of sub-Saharan Africa, with its low soil fertility and variable rainfall. Where annual food crops replace the natural grass understorey of savannah systems, water use will decrease and stream and groundwater flow change, unless tree density increases relative to the natural situation. Increasing tree density, however, will decrease crop yields, unless the trees meet specific criteria. Food crop production in the parkland systems may benefit from lower temperatures under tree canopies, but water use by trees providing this shade will prevent crops from benefiting. In old parkland trees that farmers have traditionally retained when opening fields for crops, water use per unit shade is less than in most fast growing trees introduced for agroforestry trials. Strong competition between plants adapted to years with different rainfall patterns may stabilise total system productivity -- but this will be appreciated by a farmer only if the components are of comparable value. The best precondition for farmers to maintain diversity in their agroecosystem hinges on the availability of a broad basket of choices, without clear winners or 'best bets'.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1006245605705
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  • 51
    Digitale Medien
    Digitale Medien
    Candida novakii, sp. nov. a new anamorphic yeast species of ascomycetous affinity (1997)
    Springer
    Antonie van Leeuwenhoek 71 (1997), S. 375-378 
    Details
    ISSN: 1572-9699
    Schlagwort(e): Candida novakii ; taxonomy ; yeasts
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Two strains of an undescribed species of the genus Candida were isolated from decaying wood of Quercus sp. A description of the new species Candida novakii is given.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1000238205640
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  • 52
    Digitale Medien
    Digitale Medien
    Verrucomicrobia div. nov., a new division of the Bacteria containing three new species of Prosthecobacter (1997)
    Springer
    Antonie van Leeuwenhoek 72 (1997), S. 29-38 
    Details
    ISSN: 1572-9699
    Schlagwort(e): phylogeny ; prosthecobacter ; taxonomy ; Verrucomicrobia ; Verrucomicrobiae
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Four strains of nonmotile, prosthecate bacteria were isolated in the 1970s and assigned to the genus Prosthecobacter. These strains were compared genotypically by DNA/DNA reassociation and 16S rDNA based phylogenetic analyses. Genotypic comparisons were complemented with phenotypic characterizations. Together, these studies clearly indicate each Prosthecobacter strain represents a novel species of bacteria. We propose three new species of Prosthecobacter, P. dejongeii strain FC1, P. vanneervenii strain FC2, and P. debontii strain FC3; P. fusiformis is reserved for the type strain of the genus, strain FC4. Additionally, we propose the genera Prosthecobacter and Verrucomicrobium, currently members of the order Verrucomicrobiales, to comprise a novel higher order taxonomic group, the division Verrucomicrobia div. nov. and the class Verrumicrobiae class nov. Many novel members of the Verrucomicrobia, as revealed by molecular ecology studies, await isolation and description.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1000348616863
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  • 53
    Digitale Medien
    Digitale Medien
    Studies on keratinophilic fungi. Ix: Neoarachnotheca gen. nov. and a new species of Nannizziopsis (1997)
    Springer
    Antonie van Leeuwenhoek 72 (1997), S. 149-158 
    Details
    ISSN: 1572-9699
    Schlagwort(e): keratinophilic fungi ; Neoarachnotheca ; Neoarachnotheca keratinophila ; Nannizziopsis tropicalis ; Onygenales ; taxonomy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Neoarachnotheca is proposed as a new genus of Onygenales. The outstanding generic characteristics are white, spherical ascomata with a wall formed by a network of hyphae and spherical, subhyaline ascospores with an irregular sheath. Nt. keratinophila, the type species, characterized by wavy peridial hyphae has been isolated from marine and river sediments and Myriodontium keratinophilum is its anamorph. Nannizziopsis tropicalis is proposed as a new species based on a strain isolated from soil in Burundi. RFLPs analysis of ITS and 5.8S rDNA support these proposals. The differences with related genera are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1000394118040
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  • 54
    Digitale Medien
    Digitale Medien
    Dipodascus capitatus, Dipodascus spicifer and Geotrichum clavatum: Genomic characterization (1998)
    Springer
    Antonie van Leeuwenhoek 74 (1998), S. 229-235 
    Details
    ISSN: 1572-9699
    Schlagwort(e): Dipodascus capitatus ; D.spicifer ; Geotrichum clavatum ; yeast ; taxonomy ; DNA heterogeneity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The G+C contents of 25 strains of Dipodascus capitatus, Dipodascus spicifer and Geotrichum clavatum were found to be heterogeneous on basis of derivative graphs of the melting profiles. Strains showing similar derivative graphs of the melting curve exhibited high levels of DNA homology (80-100%); strains showing dissimilar derivative graphs exhibited low levels of DNA homology (5 to 45%). Being considered separate taxa on basis of these parameters, D. capitatus, D. spicifer and G. clavatum could be identified by a combination of the key characteristics growth on xylose, cellobiose, salicin and arbutin.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1001762024710
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  • 55
    Digitale Medien
    Digitale Medien
    Stable Quasicrystalline Ground States (1997)
    Springer
    Journal of statistical physics 88 (1997), S. 691-711 
    Details
    ISSN: 1572-9613
    Schlagwort(e): Quasicrystals ; nonperiodic tilings ; classical lattice-gas models ; ground states ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract We give strong evidence that noncrystalline materials such as quasicrystals or incommensurate solids are not exceptions, but rather are generic in some regions of phase space. We show this by constructing classical lattice-gas models with translation-invariant finite-range interactions and with a unique quasiperiodic ground state which is stable against small perturbations of two-body potentials. More generally, we provide a criterion for stability of nonperiodic ground states.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/B:JOSS.0000015168.25151.22
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  • 56
    Digitale Medien
    Digitale Medien
    Renormalization of the Chapman–Enskog Expansion: Isothermal Fluid Flow and Rosenau Saturation (1998)
    Springer
    Journal of statistical physics 91 (1998), S. 285-305 
    Details
    ISSN: 1572-9613
    Schlagwort(e): Chapman–Enskog expansion ; Burnett equation ; Boltzmann equation ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract This paper continues the author's study of procedures for rewriting the well-known Chapman–Enskog expansion used in the kinetic theory of gases. The usual Chapman–Enskog expansion, when used in isothermal fluid motion, will introduce nonlinear instability at super-Burnett order O(ε3) truncation. The procedure given here eliminates the truncation instability and produces the desired dissipation inequality.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1023048322851
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  • 57
    Digitale Medien
    Digitale Medien
    Classical Lattice-Gas Models of Quasicrystals (1999)
    Springer
    Journal of statistical physics 95 (1999), S. 835-850 
    Details
    ISSN: 1572-9613
    Schlagwort(e): quasicrystals ; nonperiodic tilings ; classical lattice-gas models ; nonperiodic ground states ; nonperiodic Gibbs states ; stability ; frustration
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract One of the fundamental problems of quasicrystals is to understand their occurrence in microscopic models of interacting particles. We review here recent attempts to construct stable quasicrystalline phases. In particular, we compare two recently constructed classical lattice-gas models with translation-invariant interactions and without periodic ground-state configurations. The models are based on nonperiodic tilings of the plane by square-like tiles. In the first model, all interactions can be minimized simultaneously. The second model is frustrated; its nonperiodic ground state can arise only by the minimization of the energy of competing interactions. We put forward some hypotheses concerning stabilities of nonperiodic ground states. In particular, we introduce two criteria, the so-called strict boundary conditions, and prove their equivalence to the zero-temperature stability of ground states against small perturbations of potentials of interacting particles. We discuss the relevance of these conditions for the low-temperature stability, i.e., for the existence of thermodynamically stable nonperiodic equilibrium states.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1004542115011
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  • 58
    Digitale Medien
    Digitale Medien
    Non-Self-Similar Behavior in the LSW Theory of Ostwald Ripening (1999)
    Springer
    Journal of statistical physics 95 (1999), S. 867-902 
    Details
    ISSN: 1572-9613
    Schlagwort(e): kinetics of phase transitions ; domain coarsening ; asymptotic behavior ; self-similarity ; stability ; chaos
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The classical Lifshitz–Slyozov–Wagner theory of domain coarsening predicts asymptotically self-similar behavior for the size distribution of a dilute system of particles that evolve by diffusional mass transfer with a common mean field. Here we consider the long-time behavior of measure-valued solutions for systems in which particle size is uniformly bounded, i.e., for initial measures of compact support. We prove that the long-time behavior of the size distribution depends sensitively on the initial distribution of the largest particles in the system. Convergence to the classically predicted smooth similarity solution is impossible if the initial distribution function is comparable to any finite power of distance to the end of the support. We give a necessary criterion for convergence to other self-similar solutions, and conditional stability theorems for some such solutions. For a dense set of initial data, convergence to any self-similar solution is impossible.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1004546215920
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  • 59
    Digitale Medien
    Digitale Medien
    Identification of Taxa in the Genus shape Beta using ITS1 Sequence Information (1998)
    Springer
    Plant molecular biology reporter 16 (1998), S. 147-155 
    Details
    ISSN: 1572-9818
    Schlagwort(e): allele-specific PCR ; Beta ; ITS1 ; plant identification ; rDNA ; taxonomy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Sequence variation in the ITS1 locus of the nuclear ribosomal DNA in beets has previously been used to reconstruct phylogeny of the species in the genus Beta. We have developed protocols that allow the identification of Beta taxa by use of taxon-specific primers. Beta sections, species and subspecies can be identified. Differences within the ITS1 region of a single base can be exploited for species identification. The results from this study not only provide effective methods for wild beet identification, but also indicate the potential use of the techniques in other crops.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1007416817736
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  • 60
    Digitale Medien
    Digitale Medien
    The taxonomic impediment in orthopteran research and conservation (1998)
    Springer
    Journal of insect conservation 2 (1998), S. 151-159 
    Details
    ISSN: 1572-9753
    Schlagwort(e): Orthoptera ; biodiversity ; taxonomy ; conservation.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Wissenschaftskunde und Wissenschaftsorganisation, Hochschul- und Universitätswesen, Museumswissenschaft
    Notizen: Abstract It is estimated that only 10–15% of the world's insect fauna has been described and named. Efforts to inventory insect biodiversity are hampered by this taxonomic impediment, which is compounded by the logistical problems of an insufficient taxonomic workforce and their remote location in museums thousands of miles from the areas of highest biodiversity. Compared to most other invertebrate groups however, the taxonomic impediment is relatively benign in the order Orthoptera. This is a small to medium-sized order (approximately 20 000 described species) which is well known taxonomically, owing to the group's agricultural importance worldwide. Furthermore, orthopteran taxonomists are now fortunate to have a published up-to-date catalogue of all known species, which has just become accessible as a regularly updated database on the World Wide Web. Whilst new information technology, in the form of e-mail networks, World Wide Web sites and CD-ROM information archives, is already enhancing communication between specialists and helping to reduce the logistical problems of documenting orthopteran biodiversity, a major reinvestment in basic taxonomic research is needed if we are to reduce the existing taxonomic impediment significantly. There is general agreement that an internationally coordinated approach will be necessary and priorities must be set to tackle the biodiversity/systematics crisis. In the future, the Orthoptera can make an important contribution to invertebrate faunal surveys and have potential as an indicator taxon. Furthermore, the Orthoptera Species File establishes a taxonomic framework which could be readily enlarged to include geographic data and phenology of species from existing museum specimens.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1009633811789
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  • 61
    Digitale Medien
    Digitale Medien
    Biological control of pigweeds (Amaranthus retroflexus, L. A. Powellii, S. Watson and A. bouchonii Thell.) with phytophagous insects, fungal pathogens and crop management (1997)
    Springer
    Integrated pest management reviews 2 (1997), S. 51-59 
    Details
    ISSN: 1572-9745
    Schlagwort(e): Biological control ; insects ; pathogens ; germination ; taxonomy ; genetic variability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Pigweeds (Amaranthus spp.) are of economic importance worldwide. In Europe, Amaranthus retroflexus is one of the ten weed species of greatest economic importance. It is a serious problem weed in several field crops (e.g. maize), as well as in vegetables, orchards and grape vines. It is an annual spreading by seeds which have a long viabilityand are dispersed principally by wind and water, but also by machinery. There is great variability in seed germination which renders control with post-emergence herbicides difficult. In addition, triazine herbicide-resistant populations occur in ten European countries. The aim of this subproject of COST action 816 is to investigate the possibilities of classical and inundative biological control of Amaranthus spp., to characterize potentialbiological control agents and to develop methods for their integration with current phytosanitary measures in the target crops. The project was initiated with an extended literaturesurvey followed by field surveys for insects and pathogens associated with Amaranthus spp. in several European countries. Promising isolates of fungal pathogens have been tested ondetached leaves and whole plants, and initial studies on the application of pathogens causing damping off in seedlings have been made. Further, the variability of different provenances ofAmaranthus spp. in response to fungal attack has been investigated
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1018480429706
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  • 62
    Digitale Medien
    Digitale Medien
    Stable Sampled-data Adaptive Control of Robot Arms Using Neural Networks (1997)
    Springer
    Journal of intelligent and robotic systems 20 (1997), S. 131-155 
    Details
    ISSN: 1573-0409
    Schlagwort(e): robot adaptive control ; basis function-like networks ; stability ; discrete variable structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Maschinenbau
    Notizen: Abstract Stable neural network-based sampled-data indirect and direct adaptivecontrol approaches, which are the integration of a neural network (NN)approach and the adaptive implementation of the discrete variable structurecontrol, are developed in this paper for the trajectory tracking control ofa robot arm with unknown nonlinear dynamics. The robot arm is assumed tohave an upper and lower bound of its inertia matrix norm and its states areavailable for measurement. The discrete variable structure control servestwo purposes, i.e., one is to force the system states to be within the stateregion in which neural networks are used when the system goes out of neuralcontrol; and the other is to improve the tracking performance within the NNapproximation region. Main theory results for designing stable neuralnetwork-based sampled data indirect and direct adaptive controllers aregiven, and the extension of the proposed control approaches to the compositeadaptive control of a flexible-link robot is discussed. Finally, theeffectiveness of the proposed control approaches is illustrated throughsimulation studies.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1007900125801
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  • 63
    Digitale Medien
    Digitale Medien
    Robust Regulator for Flexible-Joint Robots Using Integrator Backstepping (1998)
    Springer
    Journal of intelligent and robotic systems 22 (1998), S. 23-38 
    Details
    ISSN: 1573-0409
    Schlagwort(e): robot dynamic model ; stiffness matrix ; constant disturbance ; integrator backstepping ; Liapunov functions ; Barbalat lemma ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Maschinenbau
    Notizen: Abstract A robust regulator for flexible-joint robots is proposed, which yields constant torque disturbance rejection acting on the links. The design uses the integrator backstepping technique [4,5] to cancel nonlinearities and disturbance not in the range space of the control. Stability of the closed loop system is shown using iterative Liapunov functions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1007947416837
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  • 64
    Digitale Medien
    Digitale Medien
    Forward Assembly Planning Based on Stability (1997)
    Springer
    Journal of intelligent and robotic systems 19 (1997), S. 411-436 
    Details
    ISSN: 1573-0409
    Schlagwort(e): assembly planning ; stability ; robot ; forward ; operations
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Maschinenbau
    Notizen: Abstract The paper presents an approach to sequence planning consisting in determining assembly sequences defined in terms of mating and non-mating operations and based on a dynamic expansion of the assembly tree obtained using a knowledge base management system. The planner considers the case of a single-robot assembly workcell. The use of stability and the detailed definition of sequences also by means of several non-mating operations are shown to be powerful instruments in the control of the tree expansion. Forward assembly planning has been chosen, in order to minimize the number of stability checks. Backtracking is avoided by combining precedence relations and stability analysis. Hard and soft constrains are introduced to drive the tree expansion. Hard constraints are precedence relations and stability analysis. All operations are associated to costs, which are used as soft constraints. The operation based approach enables one to manage even non-mating operations and to easily overcome the linearity constraint. Costs enable the planner to manage the association among tools and components. The first section of the paper concerns Stability Analysis that is subdivided into Static and Dynamic Stability Analysis. The former is mainly involved in analyzing gravity effects; the latter is mainly involved in evaluate inertia effects due to manipulation. Stability Analysis is implemented in a simplified form. Fundamental assumptions are: no rotational equilibrium condition is considered; for each reaction force only direction and versus, but not magnitude, are considered; friction is neglected. The second section discusses the structure of the planner and its implementation. The planner is a rule based system. Forward chaining and hypothetical reasoning are the inference strategies used. The knowledge base and the data base of the system are presented and the advantages obtained using a rule based system are discussed. The third section shows two planning examples, showing the performance of the system in a simple case and in an industrial test case, the assembly of a microwave branching filter composed of 26 components.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1007928631050
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  • 65
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    Digitale Medien
    Stable Neuro-Adaptive Control for Robots with the Upper Bound Estimation on the Neural Approximation Errors (1999)
    Springer
    Journal of intelligent and robotic systems 26 (1999), S. 91-100 
    Details
    ISSN: 1573-0409
    Schlagwort(e): robots ; neural networks ; adaptiveness ; stability ; approximation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Maschinenbau
    Notizen: Abstract An indirect adaptive control approach is developed in this paper for robots with unknown nonlinear dynamics using neural networks (NNs). A key property of the proposed approach is that the actual joint angle values in the control law are replaced by the desired joint angles, angle velocities and accelerators, and the bound on the NN reconstruction errors is assumed to be unknown. Main theoretical results for designing such a neuro-controller are given, and the control performance of the proposed controller is verified with simulation studies.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1008195720685
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  • 66
    Digitale Medien
    Digitale Medien
    Taxonomy and the Personal Equation: The Historical Fates of Charles Girard and Louis Agassiz (1999)
    Springer
    Journal of the history of biology 32 (1999), S. 509-555 
    Details
    ISSN: 1573-0387
    Schlagwort(e): Louis Agassiz ; Spencer Baird ; Charles Girard ; reputation ; taxonomy ; ichthyology ; Museum of Comparative Zoology ; Smithsonian Institution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geschichte
    Notizen: Abstract The reputations of scientists among their contemporaries depend not only on accomplishment, but also on interactions affected by influence and personality. The historical lore of most fields of scientific endeavor preserve these reputations, often through the identification of founders, innovators, and prolific workers whose contributions are considered fundamental to progress in the field. Historians frequently rely on the historical lore of scientists to guide their studies of the development of ideas, exhibiting justifiable caution in reassessing reputations in the light of current knowledge. However, the transmission of historical lore can obscure the relative importance of accomplishment, influence and personality in shaping contemporary reputations, leaving the historian to either accept reputations at face value or attempt to reconstruct the context in which they were created. The science of taxonomy, because of its rules of priority, leaves a relatively accurate record of historical accomplishment through the persistence of taxa in catalogues and faunal guides. These records allow the modern historian an unbiased means to assess the relative accomplishments of historical figures and therefore a means to critically reassess reputations independent of personality and influence. In the historical lore of North American ichthyology, Louis Agassiz at Harvard and Spencer Baird at the Smithsonian emerge as central figures in the early development of the field during the mid-1800s, contributing not only through the quality and quantity of their science, but also through their roles as institutional leaders and mentors to workers who followed. Charles Girard, originally a student of Agassiz's and later a coworker with Baird, receives little notice in the history of ichthyology, and his reputation is that of a minor player in the initial description of the North American fish fauna, and one whose work appears to have been flawed or even careless when compared to his contemporaries. However, a review of both contemporary and modern taxonomic works reveals that Girard's productivity far exceeded that of either Agassiz or Baird. Furthermore, an examination of the tendency of Girard and his contemporaries to introduce synonymous names into the literature, which might reflect careless or uncritical work, suggests that Girard was among the more accomplished workers of hisera, including Agassiz and Baird. Girard's low ranking in the folklore of North American ichthyology, therefore, can not be attributed to discernible shortcomings in his scientific work, but rather to a public and private campaign of criticism waged by Agassiz after Girard's departure from Harvard. While Agassiz's dispute with Girard stemmed from their personal interactions, he expressed them as criticisms of Girard's work, and thus helped shape Girard's scientific reputation as it has been transmitted through the lore of ichthyology. This case study reveals how scientific reputation may not always rest on accomplishment, but can be influenced by personal interactions obscured by time but nonetheless important to history.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1004784904703
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  • 67
    Digitale Medien
    Digitale Medien
    Emergence of symmetric, modular, and reciprocal connections in recurrent networks with Hebbian learning (1999)
    Springer
    Biological cybernetics 81 (1999), S. 211-225 
    Details
    ISSN: 1432-0770
    Schlagwort(e): Key words: Hebbian learning rule ; attractor dynamics ; symmetric connections ; multiplicative normalization ; self-organization ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Informatik , Physik
    Notizen: Abstract. While learning and development are well characterized in feedforward networks, these features are more difficult to analyze in recurrent networks due to the increased complexity of dual dynamics – the rapid dynamics arising from activation states and the slow dynamics arising from learning or developmental plasticity. We present analytical and numerical results that consider dual dynamics in a recurrent network undergoing Hebbian learning with either constant weight decay or weight normalization. Starting from initially random connections, the recurrent network develops symmetric or near-symmetric connections through Hebbian learning. Reciprocity and modularity arise naturally through correlations in the activation states. Additionally, weight normalization may be better than constant weight decay for the development of multiple attractor states that allow a diverse representation of the inputs. These results suggest a natural mechanism by which synaptic plasticity in recurrent networks such as cortical and brainstem premotor circuits could enhance neural computation and the generation of motor programs.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s004220050557
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  • 68
    Digitale Medien
    Digitale Medien
    Shear band spacing in gradient-dependent thermoviscoplastic materials (1999)
    Springer
    Computational mechanics 23 (1999), S. 8-19 
    Details
    ISSN: 1432-0924
    Schlagwort(e): Keywords: Material characteristic length ; strain-rate gradient ; dominant growth rate ; viscoplastic material ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract We study thermomechanical deformations of a viscoplastic body deformed in simple shear. The strain gradients are taken as independent kinematic variables and the corresponding higher order stresses are included in the balance laws, and the equation for the yield surface. Three different functional relationships, the power law, and those proposed by Wright and Batra, and Johnson and Cook are used to relate the effective strain rate to the effective stress and temperature. Effects of strain hardening of the material and elastic deformations are neglected. The homogeneous solution of the problem is perturbed and the stability of the problem linear in the perturbation variables is studied. Following Wright and Ockendon's postulate that the wavelength whose initial growth rate is maximum determines the minimum spacing between adjacent shear bands, the shear band spacing is computed. It is found that the minimum shear band spacing is very sensitive to the thermal softening coefficient/exponent, the material characteristic length and the nominal strain-rate. Approximate analytical expressions for the critical wave length for heat conducting nonpolar materials and locally adiabatic deformations of gradient dependent materials are also derived.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s004660050381
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  • 69
    Digitale Medien
    Digitale Medien
    Thermogravimetric studies of the synthesis of cas from gypsum, CaSo4·2H2O and phosphogypsum (1997)
    Springer
    Journal of thermal analysis and calorimetry 49 (1997), S. 1501-1507 
    Details
    ISSN: 1572-8943
    Schlagwort(e): calcium sulphide ; gypsum ; oxidation ; phosphogypsum ; reduction ; stability ; thermogravimetry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Using a heating rate of 2°C min−1, CaS reacts with oxygen in air from 700°C to form CaSO4, with a complete conversion at 1100°C. Synthesis of CaS from the reaction between CaSO4 containing compounds and carbon compounds in air would not be possible, as the carbon reacts from 600°C with oxygen in the air to give CO2. Heating stoichiometric amounts of carbon and pure CaSO4, synthetic gypsum or phosphogypsum in a nitrogen atmosphere, results in the formation of CaS from 850°C. Using a heating rate of 10°C min−1, the formation of CaS is completed at 1080°C. Addition of 5% Fe2O3 as a catalyst lowers the starting temperature of the reaction to 750°C. Activation energy values at different fraction reaction values (α) differ between 340 and 400 kJ mol−1. The relationship between the activation energy values and conversion (α) indicates that the reaction proceeds via multiple steps.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01983709
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  • 70
    Digitale Medien
    Digitale Medien
    Thermal decomposition of the magnesium, zinc, lead and niobium chelates derived from 8-quinolinol (1997)
    Springer
    Journal of thermal analysis and calorimetry 50 (1997), S. 625-632 
    Details
    ISSN: 1572-8943
    Schlagwort(e): DSC ; NMR ; 8-quinolinol compounds ; TG-DTG ; stability ; thermal decomposition
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Solid M-Ox compounds, whereM represents Mg(II), Zn(II), Pb(II) and NbO(III), and Ox is 8-quinolinol, have been prepared. Thermogravimetry, derivative thermogravimetry (TG, DTG), differential scanning calorimetry (DSC), nuclear magnetic resonance (NMR) and infrared absorption spectra (IR) have been used to characterize and to study the thermal stability and thermal decomposition of these compounds.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01979034
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  • 71
    Digitale Medien
    Digitale Medien
    Thermal Analysis, Microcalorimetry and Combined Techniques for the Study of Pharmaceuticals (1999)
    Springer
    Journal of thermal analysis and calorimetry 56 (1999), S. 1285-1304 
    Details
    ISSN: 1572-8943
    Schlagwort(e): amorphous state ; combined techniques ; drug design ; drug product development ; drug substance ; drug technology ; DSC ; excipients ; failure investigations ; hydrates ; MDSC ; microcalorimetry ; pharmaceuticals ; polymorphism ; polymers ; preformulation ; process optimization ; purity ; quality control ; solvates ; stability ; sub-ambient DSC ; TG ; temperature resolved X-ray diffraction ; water interactions ; thermal microscopy ; water sorption-desorption
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Modern thermal analysis, microcalorimetry and new emerging combined techniques which deliver calorimetric, microscopic and spectroscopic data offer a powerful analytical battery for the study of pharmaceuticals. These techniques are very useful in all steps of development of new drug products as well as methods for quality control in production. The characterization of raw materials enables to understand the relationships between polymorphs, solvates and hydrates and to choose the proper development of new drug products with very small amount of material in a very short time. Information on stability, purity is valuable for new entities as well as for marketed drug substances from different suppliers. Excipients which vary from single organic or inorganic entity to complexes matrixes or polymers need to be characterized and properly controlled. The thermodynamic phase-diagrams are the basis of the studies of drug-excipients interactions. They are very useful for the development of new delivery systems. A great number of new formulations need proper knowledge of the behaviour of the glass transition temperature of the components. Semi-liquid systems, interactions in aqueous media are also successfully studied by these techniques.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1010194020563
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  • 72
    Digitale Medien
    Digitale Medien
    Evaluation of the stability of substituted InF3 glasses by differential thermal analysis (1997)
    Springer
    Journal of thermal analysis and calorimetry 50 (1997), S. 807-814 
    Details
    ISSN: 1572-8943
    Schlagwort(e): DTA ; stability ; substituted InF3 glasses
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The thermal properties and devitrification behaviour of substituted InF3 glasses were studied by means of differential thermal analysis. A comparison of various simple quantitative methods to assess the level of stability of multicomponent fluoride glass systems was also made. Most of these methods are based on critical temperatures. In this paper, a new parameter,k d(T), is introduced to the stability criteria. The stabilities of several substituted InF3 glasses were evaluated experimentally and correlated with the activation energies of crystallization via this new kinetic criterion and compared with those evaluated by other criteria.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01979210
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  • 73
    Digitale Medien
    Digitale Medien
    Ignitability of Polymers Related to Polymer Properties and Different Steady States of Combustion Theoretical Approach (1999)
    Springer
    Journal of thermal analysis and calorimetry 55 (1999), S. 727-739 
    Details
    ISSN: 1572-8943
    Schlagwort(e): ignition ; polymer combustion modelling ; stability ; steady state
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract A mathematical model of ignition and burning of organic polymers was used for evaluation and quantification of the tendency of polymers to ignition. The model permits investigation of the influence of one parameter of the polymer on the others. It was found that the model could be used for the verification of the ignitability method developed by Miller et al. [1]. Different steady states of combustion were found when using the model proposed. There is a characteristic steady state for normal flaming combustion, another for non-flaming combustion, and there are also unstable steady states that have no real physical meaning.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1010157011275
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  • 74
    Digitale Medien
    Digitale Medien
    Thermodynamics of a 24-Mer Triple Helix Formation and Stability (1999)
    Springer
    Journal of thermal analysis and calorimetry 56 (1999), S. 1177-1184 
    Details
    ISSN: 1572-8943
    Schlagwort(e): differential scanning calorimetry ; DNA triple helix ; oligonucleotides ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract In this work we report a thermodynamic characterization of stability and melting behaviour of two 24-mer DNA triplexes. The third strand, that binds the Watson-Crick double helix with Hoogsteen hydrogen bonds, contains 3′-3′ phosphodiester junction that determines the polarity inversion. The target double helix is composed of adjacent and alternate fragments of oligopurine-oligopyrimidine tracts. The two helices differ from the substitution of the cytosine, involved in the junction, with the thymine. Calorimetric data reported here provide a quantitative measure of the influence of pH and base modification on the stability of a DNA triplex.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1010117431041
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  • 75
    Digitale Medien
    Digitale Medien
    Rapid isolation of muscle and heart mitochondria, the lability of oxidative phosphorylation and attempts to stabilize the process in vitro by taurine, carnitine and other compounds (1997)
    Springer
    Molecular and cellular biochemistry 174 (1997), S. 61-66 
    Details
    ISSN: 1573-4919
    Schlagwort(e): heart mitochondria ; lability ; muscle mitochondria ; oxidative phosphorylation ; stability ; taurine
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: Abstract We modified the isolation procedure of muscle and heart mitochondria. In human muscle, this resulted in a 3.4 fold higher yield of better coupled mitochondria in half the isolation time. In a preparation from rat muscle we studied factors that affected the stability of oxidative phosphorylation (oxphos) and found that it decreased by shaking the preparation on a Vortex machine, by exposure to light and by an increase in storage temperature. The decay was found to be different for each substrate tested. The oxidation of ascorbate was most stable and less sensitive to the treatments. When mitochondria were stored in the dark and the cold, the decrease in oxidative phosphorylation followed first order kinetics. In individual preparations of muscle and heart mitochondria, protection of oxidative phosphorylation was found by adding candidate stabilizers, such as desferrioxamine, lazaroids, taurine, carnitine, phosphocreatine, N-acetylcysteine, Trolox-C and ruthenium red, implying a role for reactive oxygen species and calcium-ions in the in vitro damage at low temperature to oxidative phosphorylation. In heart mitochondria oxphos with pyruvate and palmitoylcarnitine was most labile followed by glutamate, succinate and ascorbate.We studied the effect of taurine, hypotaurine, carnitine, and desferrioxamine on the decay of oxphos with these substrates. 1 mM taurine (n = 6) caused a significant protection of oxphos with pyruvate, glutamate and palmitoylcarnitine, but not with the other substrates. 5 mM L-carnitine (n = 6), 1 mM hypotaurine (n = 3) and 0.1 mM desferrioxamine (n = 3) did not protect oxphos with any of the substrates at a significant level. These experiments were undertaken in the hope that the in vitro stabilizers can be used in future treatment of patients with defects in oxidative phosphorylation. (Mol Cell Biochem 174: 61–66, 1997)
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1006803807814
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  • 76
    Digitale Medien
    Digitale Medien
    Markov Control Processes with the Expected Total Cost Criterion: Optimality, Stability, and Transient Models (1999)
    Springer
    Acta applicandae mathematicae 59 (1999), S. 229-269 
    Details
    ISSN: 1572-9036
    Schlagwort(e): (discrete-time) Markov control processes ; expected total cost ; value iteration ; policy iteration ; stability ; transient control models
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract This paper studies the expected total cost (ETC) criterion for discrete-time Markov control processes on Borel spaces, and possibly unbounded cost-per-stage functions. It presents optimality results which include conditions for a control policy to be ETC-optimal and for the ETC-value function to be a solution of the dynamic programming equation. Conditions are also given for the ETC-value function to be the limit of the α-discounted cost value function as α ↑ 1, and for the Markov control process to be `stable" in the sense of Lagrange and almost surely. In addition, transient control models are fully analized. The paper thus provides a fairly complete, up-dated, survey-like presentation of the ETC criterion for Markov control processes on Borel spaces.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1006368714127
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  • 77
    Digitale Medien
    Digitale Medien
    Resilience in the Dynamics of Economy-Environment Systems (1998)
    Springer
    Environmental and resource economics 11 (1998), S. 503-520 
    Details
    ISSN: 1573-1502
    Schlagwort(e): biodiversity ; dynamics ; resilience ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik , Wirtschaftswissenschaften
    Notizen: Abstract The ecological concept of resilience has begun to inform analysis of change in economy-environment systems. The linkages between resilience and the stability of dynamical systems are discussed, along with its role in understanding of the evolution of such systems. Particular linkages discussed include those between resilience, biodiversity and the sustainability of alternative states. Recent developments in modelling the resilience of joint economy-environment systems suggest the advantages of analysing change in the system as a Markov process, the transition probabilities between states offering a natural measure of the resilience of the system in such states. It is argued that this ‘emergent property’ of the collaboration between ecology and economics has far-reaching implications for the way we think about, model and manage the environmental sustainability of economic development.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1008255614276
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  • 78
    Digitale Medien
    Digitale Medien
    Influence of Taxonomy, Ecology, and Seasonality in River Stage on Fish Contamination Risks in Floodplain Swamps of the Lower Mississippi River (1998)
    Springer
    Ecotoxicology 7 (1998), S. 325-334 
    Details
    ISSN: 1573-3017
    Schlagwort(e): contamination risks ; fish ; Mississippi River ; ecological factors ; taxonomy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract We compared contamination levels in fish from contaminated and uncontaminated floodplain swamps of the lower Mississippi River to assess differences in contamination risks between swamps, across different taxonomic and ecological groupings of fishes within and between swamps, and with seasonality in river stage. Fish tissue levels of inorganic contaminants were substantially lower than environmental levels in both swamps, suggesting either that fish were not uptaking these contaminants, or they were effectively eliminating the contaminants from their bodies. Tissue levels of organic contaminants were high relative to environmental levels, suggesting that these contaminants were bioaccumulating. Organic contaminants were significantly higher in fish from the contaminated swamp (Devil's Swamp) than in fish from a reference swamp up river (Tunica Swamp). Because the organic contaminants were largely confined to sediments, we expected bottom-oriented fishes to have higher concentrations than pelagic fishes. Assuming that uptake was primarily through the food chain, we expected top predators to exhibit higher concentrations than low-level consumers. We also expected year- round swamp residents to exhibit higher accumulations than more transitory users of backswamp habitat. However, organic contaminant levels did not differ in the directions expected for any of these groupings. We did observe differences in organic contaminant levels within and between swamps for different taxonomic groupings of fishes (species and genera). Some taxa occupying low to middle positions in the food web (e.g., gizzard shad, Lepomis spp.) exhibited higher concentrations than taxa near the top of the food web. Within Devil's Swamp, organic contaminant levels were significantly higher at low river stage, when fish were confined to the swamp, than at high river stage, when fish were free to move between the river and the swamp. We caught more species and more fish per unit effort in Devil's Swamp than in Tunica Swamp, contrary to expectations if contaminants in the former were negatively impacting population and community structure. Species richness differences between swamps were a consequence of catch differences, with higher catch corresponding to inclusion of more rare species. The lower catch in Tunica Swamp may have resulted from physical modifications of its waterways to support agriculture and hunting. The results of this study underscore the importance in factoring information on the taxonomy and ecology of organisms, and seasonal changes in environmental conditions, into assessments of contamination risks.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1008811713427
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  • 79
    Digitale Medien
    Digitale Medien
    Coating of Sol Particles for Membrane Applications (1997)
    Springer
    Journal of sol gel science and technology 8 (1997), S. 523-527 
    Details
    ISSN: 1573-4846
    Schlagwort(e): UF membranes ; alumina ; zirconia coating ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract For improving chemical and thermal stability of γ -Al2O3 membranes boehmite (AlOOH) sol-particles are coated with Zr4+-species with two techniques. These techniques are heterogeneous precipitation (HP-method) and “surface-reaction-followed-by-polycondensation” (SRPC-method). A continuous coating layer is formed at relative low Zr4+-concentration, about one monolayer coverage of boehmite particles, and with the HP-method. For larger concentrations and for the SRPC-method small particles (order 1 nm) of Zr4+-species are formed on the surface of the boehmite particles. After drying and calcination up to 1000°C no continuous layer of a zirconia phase could be detected for all samples. However the thermal stability of the porous structure is improved. Phase transitions of alumina occur at temperatures of 1100°C and the porous structure of the membrane material is then destabilized.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1018318815719
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  • 80
    Digitale Medien
    Digitale Medien
    Coating of sol particles for membrane applications (1997)
    Springer
    Journal of sol gel science and technology 8 (1997), S. 523-527 
    Details
    ISSN: 1573-4846
    Schlagwort(e): UF membranes ; alumina ; zirconia coating ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract For improving chemical and thermal stability of γ-Al2O3 membranes boehmite (AlOOH) sol-particles are coated with Zr4+-species with two techniques. These techniques are heterogeneous precipitation (HP-method) and “surface-reaction-followed-by-polycondensation” (SRPC-method). A continuous coating layer is formed at relative low Zr4+-concentration, about one monolayer coverage of boehmite particles, and with the HP-method. For large concentrations and for the SRPC-method small particles (order 1 nm) of Zr4+-species are formed on the surface of the boehmite particles. After drying and calcination up to 1000°C no continuous layer of a zirconia phase could be detected for all samples. However the thermal stability of the porous structure is improved. Phase transitions of alumina occur at temperatures of 1100°C and the porous structure of the membrane material is then destabilized.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02436893
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  • 81
    Digitale Medien
    Digitale Medien
    Bicelle-based liquid crystals for NMR-measurement of dipolar couplings at acidic and basic pH values (1999)
    Springer
    Journal of biomolecular NMR 13 (1999), S. 187-191 
    Details
    ISSN: 1573-5001
    Schlagwort(e): alignment ; bicelle ; dipolar coupling ; liquid crystal ; pH ; stability ; ubiquitin
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract It is demonstrated that mixtures of ditetradecyl- phosphatidylcholine or didodecyl-phoshatidylcholine and dihexyl- phosphatidylcholine in water form lyotropic liquid crystalline phases under similar conditions as previously reported for bicelles consisting of dimyristoyl-phosphatidylcholine (DMPC) and dihexanoyl- phosphatidylcholine (DHPC). The carboxy-ester bonds present in DMPC and DHPC are replaced by ether linkages in their alkyl analogs, which prevents acid- or base-catalyzed hydrolysis of these compounds. 15N-1H dipolar couplings measured for ubiquitin over the 2.3–10.4pH range indicate that this protein retains a backbone conformation which is very similar to its structure at pH 6.5 over this entire range.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1008395916985
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  • 82
    Digitale Medien
    Digitale Medien
    Lanceispora amphibia gen. et sp. nov., a new amphisphaeriaceous ascomycete inhabiting senescent and fallen leaves of mangrove (1997)
    Springer
    Mycoscience 38 (1997), S. 207-213 
    Details
    ISSN: 1618-2545
    Schlagwort(e): Bruguiera gymnorrhiza ; ecology ; Lanceispora amphibia ; mangrove ; taxonomy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Lanceispora amphibia gen. et sp. nov. in the Amphisphaeriaceae is described from senescent and fallen leaves ofBruguiera gymnorrhiza in mangrove forests in the Southwest Islands, Japan. The fungus produces immersed ascomata in leaf tissue, cylindrical asci with an apical ring staining blue with iodine, and oblanceolate ascospores with a septum above the middle. Studies on the fungal succession on the mangrove leaves revealed thatL. amphibia infects senescent leaves on the tree and inhabits intertidal fallen leaves, showing the highest frequency of occurrence at the late stage of decomposition. In culture the optimal conditions for hyphal growth were 20 ppt salinity and 30°C, and those for sexual reproduction were 10 ppt salinity and 25°C. Growth at 0 ppt (fresh water) was depressed. The fungus has amphibious habits, growing on the tree and in intertidal water; and it is adapted to the high osmotic conditions in leaf tissues of the mangrove tree and to the subtropical, brackish water environment of mangrove forests.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02460855
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  • 83
    Digitale Medien
    Digitale Medien
    Taxonomical studies on ovariicolous ustomycetes on caryophyllaceae I.Ustilago jehudana andUstilago moenchiae-manticae (1997)
    Springer
    Mycoscience 38 (1997), S. 323-328 
    Details
    ISSN: 1618-2545
    Schlagwort(e): Bauhinus ; Microbotryum ; taxonomy ; Ustilago ; ustomycetes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A study of the type specimen ofUstilago jehudana resulted in the correction of the diagnosis. The sori are localized in the host gynoecium but not in the anthers. Morphological characters of the sori and ustospores of the later describedU. moenchiae-manticae are identical with these ofU. jehudana. Ustilago moenchiae-manticae is reduced here to a synonym ofU. jehudana. The smut is reported as new to Bulgaria on a new host, viz.,Moenchia erecta. A new combination,Bauhinus jehudanus, is proposed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02464090
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  • 84
    Digitale Medien
    Digitale Medien
    Morphology and molecular phylogeny ofTretopileus sphaerophorus, a synnematous hyphomycete with basidiomycetous affinities (1998)
    Springer
    Mycoscience 39 (1998), S. 21-30 
    Details
    ISSN: 1618-2545
    Schlagwort(e): Aphyllophorales ; ribosomalDNA ; synnematous hyphomycete ; taxonomy ; Tretopileus sphaerophorus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Tretopileus sphaerophorus, a synnematous hyphomycete with basidiomycetous affinities was newly isolated from the decaying petiole and peduncle ofCocos nucifera collected in Depok, Indonesia. The species produced first a bulbil as a propagule on the top of a synnema. After the bulbil had fallen, the synnema proliferated about seven times to produce new bulbils, each time making conspicuous nodes at the upper part. By careful morphological observation, clamp connections were confirmed on the hyphae in the specimens and culture. In culture, each hyphal cell with or without a clamp was found to be dikaryotic by DAPI nuclear staining. Germination of the bulbils occurred first from projecting hyphal tips on their upper surface, which have been treated as germ pores. The inner structure of the bulbils, the hyaline mucus of the bulbils, and conidium-like hyphal fragments were also examined. Phylogenetically,T. sphaerophorus was inferred to be related to the Aphyllophorales based on the nuclear encoded small subunit (18S) rDNA using the homology search system (FASTA) and the neighbour-joining method.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02461574
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  • 85
    Digitale Medien
    Digitale Medien
    The order phyllachorales: Taxonomic review (1998)
    Springer
    Mycoscience 39 (1998), S. 97-104 
    Details
    ISSN: 1618-2545
    Schlagwort(e): Loculoascomycetes ; phyllachoraceae ; phyllachorales ; taxonomy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The order Phyllachorales contains ascomycetous fungi of considerable economic importance. The group is represented mostly by foliar parasites which produce perithecia under a clypeus, inside a stroma, or do not produce any stromatic tissue. A major taxonomic problem with this order is the lack of reliable morphological characters that clearly delimit the entire group. The main purpose of this review is to provide a clear picture of the taxonomic relationships of the order Phyllachorales, along with a key to the most important genera in the family Phyllachoraceae.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02461586
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  • 86
    Digitale Medien
    Digitale Medien
    Mycena auricoma, a new species ofMycena sectionRadiatae from Japan, andMycena spinosissima, a new record in Japan (1999)
    Springer
    Mycoscience 40 (1999), S. 73-80 
    Details
    ISSN: 1618-2545
    Schlagwort(e): Mycena auricoma ; Mycena sect.Radiatae ; Mycena spinosissima ; taxonomy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Two lignicolous species ofMycena (Agaricales, Basidiomycetes) are described and illustrated from eastern, Japan:Mycena auricoma sp. nov., forming ephemeral coprinoid basidiomata and belonging to sectionRadiatae, was found on a dead fallen twig ofQuercus serrata. It appears to close to a Malaysian species,“Trogia” crinipelliformis. Mycena spinosissima in sectionSacchariferae, new to Japan, was collected from dead bark ofAphananthe aspera, a dead fallen inflorescence ofCryptomeria japonica, and a dead fallen twig ofQuercus serrata.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02465677
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  • 87
    Digitale Medien
    Digitale Medien
    Macrocyst formation in three dictyostelid species,Dictyostelium monochasioides, Polysphondylium candidum, andP. pseudo-candidum (1999)
    Springer
    Mycoscience 40 (1999), S. 359-361 
    Details
    ISSN: 1618-2545
    Schlagwort(e): cellular slime molds ; dictyostelids ; macrocyst ; mating system ; taxonomy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Macrocyst formation in the sexual cycle was found in three dictyostelid species:Dictyostelium monochasioides, Polysphondylium candidum, andP. pseudo-candidum. Mating tests suggested thatD. monochasioides andP. pseudocandidum were heterothallic andP. candidum was homothallic. The primary walls of macrocysts had partially or fully degenerated, while the inner walls, believed to be tertiary walls, showed an undulate structure.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02463881
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  • 88
    Digitale Medien
    Digitale Medien
    A pseudospectral method for vorticity equations on spherical surface (1997)
    Springer
    Acta mathematicae applicatae sinica 13 (1997), S. 176-187 
    Details
    ISSN: 1618-3932
    Schlagwort(e): Spherical surface ; pseudospectral method ; vorticity equations ; stability ; convergence
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract The pseudospectral method for solving vorticity equations on spherical surface is discussed. An interpolation procedure, which is different from the usual ones, is proposed. Based on such an interpolation, the pseudospectral scheme is constructed. Its generalized stability and convergence are analyzed rigorously. The theoretical analysis and computational skills can also be applied to other nonlinear partial differential equations defined on spherical surface.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02015139
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  • 89
    Digitale Medien
    Digitale Medien
    A synopsis of the genusScleromitrula (=Verpatinia) (Ascomycotina: Helotiales: Sclerotiniaceae) (1997)
    Springer
    Mycoscience 38 (1997), S. 55-69 
    Details
    ISSN: 1618-2545
    Schlagwort(e): discomycetes ; ITS rDNA phylogeny ; morphology ; taxonomy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The systematics ofScleromitrula andVerpatinia of the family Sclerotiniaceae is reevaluated on the basis of morphological, cultural and molecular criteria.Scleromitrula shiraiana, Verpatinia species andCiborinia candolleana share gross morphological, microanatomical and cultural features which clearly distinguish them from the closely relatedCiborinia andRutstroemia species. Phylogenetic analyses of sequences from the internal transcribed spacer region (ITS1, ITS2, and the 5.8S gene) of nuclear ribosomal DNA demonstrate that the stipitate-capitate specimens ofScleromitrula andVerpatinia species plus the stipitate-cupulateCiborinia candolleana constitute a monophyletic clade separate from a clade including the type species ofCiborinia. Scleromitrula is emended to includeS. shiraiana, the new speciesS. rubicola, C. candolleana, and specimens formerly assigned toVerpatinia. A key to the accepted species ofScleromitrula is provided.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02464969
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  • 90
    Digitale Medien
    Digitale Medien
    Ypsilonidium bananisporum sp. nov. (Ceratobasidiales) from Iriomote Island, Japan (1997)
    Springer
    Mycoscience 38 (1997), S. 71-73 
    Details
    ISSN: 1618-2545
    Schlagwort(e): Ceratobasidiaceae ; Japan ; taxonomy ; Ypsilonidium bananisporum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Ypsilonidium bananisporum sp. nov. belonging to Ceratobasidiales is described and illustrated. This fungus has all the characteristics of the genusYpsilonidium including reticulate-hypochnoid basidiomes, broad hyphae branching at right angles, broadly clavate basidia with two sterigmata, and basidiospores germinating by repetition. It differs from all hitherto known species in the genus by producing suballantoid to banana-shaped basidiospores, measuring 19.5–22×5.5–6 μm.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02464970
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  • 91
    Digitale Medien
    Digitale Medien
    Myxomycetes from Israel IV (1997)
    Springer
    Mycoscience 38 (1997), S. 87-89 
    Details
    ISSN: 1618-2545
    Schlagwort(e): Israel ; Mycomycetes ; Physarales ; Stemonitales ; taxonomy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Ten taxa of myxomycetes growing mainly withEucalyptus, oak and pine are described. They were found in Upper Galilee, Mt. Carmel and Central parts of the country and all are new to Israel.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02464974
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  • 92
    Digitale Medien
    Digitale Medien
    Mycoleptodiscus terrestris from black pepper roots in the Dominican Republic (1997)
    Springer
    Mycoscience 38 (1997), S. 91-94 
    Details
    ISSN: 1618-2545
    Schlagwort(e): hyphomycetes ; identification ; taxonomy ; Tuberculariaceae ; Tuberculariales
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Mycoleptodiscus terrestris from black pepper roots in the Dominican Republic is described together with some notes and photomicrographs.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02464975
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  • 93
    Digitale Medien
    Digitale Medien
    Microsphaeropsis rugospora, a new species from Japanese soil (1997)
    Springer
    Mycoscience 38 (1997), S. 429-431 
    Details
    ISSN: 1618-2545
    Schlagwort(e): coelomycete ; Japan ; Microsphaeropsis rugospora ; soil fungus ; taxonomy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Beschreibung / Inhaltsverzeichnis: Abstract In an exploratory survey of soil-borne mitosporic fungi as producers of secondary metabolites useful to the pharmaceutical industry, a pale yellow pycnidial coelomycete was encountered and isolated on potato-dextrose agar. The fungus was characterized as follows: rapid growth on common media, conidiomata which are non-pulvinate, semi-immersed to immersed, nearly globose, glabrous, with a slightly papillate ostiole; pale yellowish brown, translucent, membranaceous peridium; discrete, ampulliform, monophialidic conidiogenous cells; and onecelled, dark brown, globose, thick-walled, rugose conidia which germinate very easily. In accordance with this profile, our isolate is included in the genusMicrosphaeropsis Höhnel. (Morgan-Jones, 1974a, b; Sutton, 1977, 1980; Morgan-Jones and White, 1987; Heiny et al., 1992; Katumoto, 1992). However, it proved to be sufficiently different from all described species ofMicrosphaeropsis to warrant its description as a new species.
    Notizen: Abstract A new species ofMicrosphaeropsis (Sphaeropsidales, Coelomycetes),M. rugospora, is described and illustrated. This fungus is characterized by its rapid growth on common media such as oatmeal and potato-carrot agars; semi-immersed to immersed, nearly globose, papillate pycnidias; pale yellowish brown, translucent, membranaceous peridium; monophialidic, ampulliform conidiogenous cells; and one-celled, dark brown, globose conidia ornamented with distinct tubercles. The holotype was isolated from the cultivated soil in Tanegashima Island, southern Japan.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02461683
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  • 94
    Digitale Medien
    Digitale Medien
    On some species ofMycogloea (1998)
    Springer
    Mycoscience 39 (1998), S. 31-36 
    Details
    ISSN: 1618-2545
    Schlagwort(e): Mycogloea ; Platygloea ; Platygloeaceae ; Platygloeales ; taxonomy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Three new species ofMycogloea are described and illustrated; they are:M. amethystina from Canada,M. nipponica, from Japan, andM. bullata from Thailand.Mycogloea tahitiensis is reported from Japan and additional undescribed taxa in the genus are briefly noted. Some characteristics of the genus are discussed, and a key is provided for six species recognized at this time.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02461575
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  • 95
    Digitale Medien
    Digitale Medien
    Cryptophiale sphaerospora sp. nov. occurring onJanetia synnematosa (1999)
    Springer
    Mycoscience 40 (1999), S. 189-191 
    Details
    ISSN: 1618-2545
    Schlagwort(e): bamboo fungus ; hyperparasitism ; hyphomycetes ; mycoparasites ; taxonomy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Cryptophiale sphaerospora sp. nov. is described and illustrated based on a single collection attached to a synnematous fungus,Janetia synnematosa, from a dead bamboo culm. It differs from other species ofCryptophiala in having spherical to subspherical conidia and a cerebroid layer of phialides. The overall morohology of this species is smaller than that of previously described species.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02464297
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  • 96
    Digitale Medien
    Digitale Medien
    Different levels of morphometric variation in three heterogamous dogrose species (Rosa sect.Caninae, Rosaceae) (1997)
    Springer
    Plant systematics and evolution 204 (1997), S. 207-224 
    Details
    ISSN: 1615-6110
    Schlagwort(e): Rosaceae ; Rosa sect.Caninae ; Systematics ; taxonomy ; genetic variation ; hemisexual ; apomixis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Difficulties in delimiting well-defined entities in the dogroses (Rosa sect.Caninae) has resulted in very variable taxonomic treatments. The present study was undertaken to provide a background for taxonomy as well as plant breeding. Morphometric diversity was analysed on seedlings obtained from field collections in South Sweden of three species,Rosa dumalis, R. rubiginosa andR. villosa. A canonical variates analysis showed that the three species are relatively distinct whereas two subspecies ofR. dumalis were less well discriminated. Analyses of variance demonstrated that intraspecific variation is pronounced inR. dumalis and, to a lesser extent, inR. villosa.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00989206
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  • 97
    Digitale Medien
    Digitale Medien
    Anchusella, a new genus ofBoraginaceae from the Central-Eastern Mediterranean (1997)
    Springer
    Plant systematics and evolution 205 (1997), S. 241-264 
    Details
    ISSN: 1615-6110
    Schlagwort(e): Boraginaceae ; Boragineae ; Anchusella ; A. variegata ; A. cretica ; Lycopsis ; Anchusa ; Mediterranean flora ; macromorphology ; micromorphology ; karyology ; taxonomy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The two closely related speciesLycopsis variegata andAnchusa cretica, formerly placed inAnchusa subg.Rivinia, were compared with the type species ofLycopsis andAnchusa, on the basis of a set of macro and microcharacters. The presence of only two fertile stamens as well as other peculiar characters in flower structure, androecium, gynoecium, pollen and fruit, supports the institution of the new genusAnchusella, consisting ofA. variegata andA. cretica. Karyological and eco-chorological aspects are consistent with morphological data in pointing to the autonomy of this genus, which appears characterized by autapomorphic, advanced traits.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01464408
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  • 98
    Digitale Medien
    Digitale Medien
    Comparative HPLC analysis of seed albumins fromVicia faba andV. kalakhensis (Fabaceae) (1997)
    Springer
    Plant systematics and evolution 208 (1997), S. 1-9 
    Details
    ISSN: 1615-6110
    Schlagwort(e): Fabaceae ; Vicia faba ; V. kalakhensis ; Seed albumins ; HPLC ; taxonomy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Previously reported electrophoretic seed albumin data have shown an unexpected association ofVicia faba withV. kalakhensis. In the present work, seed albumins ofV. faba (subsp.paucijuga and subsp.faba) were compared with those ofV. kalakhensis using ionexchange (IE) and reversed-phase (RP) high-performance liquid chromatography (HPLC). Two subspecies ofV. faba displayed similar seed albumin profiles. On the other hand, seed albumin profiles ofV. faba andV. kalakhensis showed no major protein peak in common either in IE-HPLC or RP-HPLC chromatograms. The reported differences in seed albumin composition ofV. faba andV. kalakhensis are consistent with other taxonomical data showingV. faba to be genetically distant from the wild relatives.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00986078
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  • 99
    Digitale Medien
    Digitale Medien
    Electrophoretic seed albumin patterns inVicia species of sectt.Hypechusa andPeregrinae (Fabaceae) (1997)
    Springer
    Plant systematics and evolution 208 (1997), S. 239-248 
    Details
    ISSN: 1615-6110
    Schlagwort(e): Fabaceae ; Vicia ; sect.Hypechusa ; sect.Peregrinae ; Electrophoresis ; seed albumins ; taxonomy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract This work is a continuation of electrophoretic investigations aimed at revealing a wild relative ofVicia faba. Electrophoretic analysis (PAGE) of seed albumins covered 52 accessions representing eightVicia species of sect.Hypechusa and two species of sect.Peregrinae. Most of the examined species showed an intraspecific variation due to differences between accessions and/or individual variation within accessions. In spite of the intraspecific variation, marked interspecific differences were recorded. However, none of the investigated species displayed electrophoretic seed albumin patterns similar to those reported earlier forV. faba. Contribution of the obtained results to characterization of the examined taxa is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00985444
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  • 100
    Digitale Medien
    Digitale Medien
    Phylogenetic relationships betweenVicia faba (Fabaceae) and related species inferred from chloroplasttrnL sequences (1998)
    Springer
    Plant systematics and evolution 212 (1998), S. 247-259 
    Details
    ISSN: 1615-6110
    Schlagwort(e): Fabaceae ; Vicia faba ; trnL intron ; PCR-sequencing ; taxonomy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The chloroplasttrnL intron from 46 differentVicia accessions, representing five of the nine sections of the genusVicia subg.Vicia sensuMaxted (1991a) were amplified by the Polymerase Chain Reaction (PCR) using oligonucleotide primers homologous to conserved regions intrnL. The products fell into two distinct groups; those of approximately 250 nt and those of around 450 nt in length. Of these, products from 17 differentVicia species were cloned and their nucleotide sequences determined. Multiple alignments were assembled and phylogenetic trees constructed by the weighted least-squares distance method. ALathyrus latifolius trnL intron sequence was used as an outgroup. The resulting trees clearly group and separate the sectt.Narbonensis, Bithynica andFaba species but were less able to distinguish species from sectt.Hypechusa andPeregrinae. Based on these sequence data,V. faba appears to be more distant from sect.Narbonensis than sectt.Hypechusa andPeregrinae. The results are in general agreement with a recent treatment ofVicia subg.Vicia (Maxted 1993) and lend further support to placingV. faba in the monospecific sect.Faba.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01089741
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