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  • Articles  (117)
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  • 1995-1999  (117)
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  • 1998  (60)
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  • 1
    Electronic Resource
    Electronic Resource
    Reachability of locational Nash equilibria (1998)
    Springer
    OR spectrum 20 (1998), S. 101-107 
    Details
    ISSN: 1436-6304
    Keywords: Competitive location model ; Nash equilibria ; stability ; reachability ; Wettbewerbsmodelle in der Standorttheorie ; Nash Gleichgewicht ; Stabilität ; Erreichbarkeit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Description / Table of Contents: 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.
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01539861
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  • 2
    Electronic Resource
    Electronic Resource
    Reachability of locational Nash equilibria (1998)
    Springer
    OR spectrum 20 (1998), S. 101-107 
    Details
    ISSN: 1436-6304
    Keywords: Key words: Competitive location model ; Nash equilibria ; stability ; reachability ; Schlüsselwörter: Wettbewerbsmodelle in der Standorttheorie ; Nash Gleichgewicht ; Stabilität ; Erreichbarkeit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Description / Table of Contents: 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?”
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002910050058
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  • 3
    Electronic Resource
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    Money demand stability: Evidence from Spain (1998)
    Springer
    Empirical economics 23 (1998), S. 387-400 
    Details
    ISSN: 1435-8921
    Keywords: Key words: Money demand ; cointegration ; stability ; regime shift ; JEL classification: E41 ; C22
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001810050027
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  • 4
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    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
    Keywords: Keywords: groundwater flow ; inverse problems ; stability ; geostatistical interpolation ; kriging.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004770050017
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  • 5
    Electronic Resource
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    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
    Keywords: Epidemiology ; sleeping sickness ; vector controls ; differential equations ; spacialization ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1001776926167
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  • 6
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    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
    Keywords: Fourth-order solitary waves ; stability ; instability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022644629950
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  • 7
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    Stability of Semilinear Delay Equations with Positive Solutions (1997)
    Springer
    Positivity 1 (1997), S. 319-330 
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    ISSN: 1572-9281
    Keywords: delay equations ; stability ; positive solutions ; spectral growth condition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009725823213
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  • 8
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    Some Results on Stability of Retarded Functional Differential Equations Using Dichotomic Map Techniques (1998)
    Springer
    Positivity 2 (1998), S. 229-238 
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    ISSN: 1572-9281
    Keywords: asymptotic stability ; dichotomic maps ; retarded functional differential equation ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009742807025
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  • 9
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    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
    Keywords: multi‐server queue ; customer class ; state‐dependent routing ; stability ; Markov chain ; fluid limit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: 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.
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    URL: http://dx.doi.org/10.1023/A:1019175812444
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  • 10
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    Stability-Like Properties of Differential Inclusions (1997)
    Springer
    Set-valued analysis 5 (1997), S. 73-88 
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    ISSN: 1572-932X
    Keywords: differential inclusion ; invariance ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: 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.
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    URL: http://dx.doi.org/10.1023/A:1008683223676
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  • 11
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    Optimization and Stability Results Through Cone Lower Semicontinuity (1997)
    Springer
    Set-valued analysis 5 (1997), S. 365-375 
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    ISSN: 1572-932X
    Keywords: set-valued mappings ; vector optimization ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008653120360
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  • 12
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    Piecewise linear test functions for stability and instability of queueing networks (1997)
    Springer
    Queueing systems 27 (1997), S. 205-226 
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    ISSN: 1572-9443
    Keywords: multiclass queueing networks ; ergodicity ; stability ; performance analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019166115653
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  • 13
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    On the guaranteed throughput and efficiency of closed re-entrant lines (1998)
    Springer
    Queueing systems 28 (1998), S. 33-54 
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    ISSN: 1572-9443
    Keywords: queueing networks ; throughput ; closed networks ; efficiency ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019199022922
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  • 14
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    Discrete time semigroup transformations with random perturbations (1997)
    Springer
    Journal of dynamics and differential equations 9 (1997), S. 463-505 
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    ISSN: 1572-9222
    Keywords: Difference equations ; random perturbation ; averaging ; diffusion approximation ; randomly perturbed iterations ; stability ; 3SR60 ; 60H15 ; 60J99
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02227491
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  • 15
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    On Stability and Boundedness for Lipschitzian Differential Inclusions: The Converse of Lyapunov's Theorems (1997)
    Springer
    Set-valued analysis 5 (1997), S. 377-390 
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    ISSN: 1572-932X
    Keywords: differential inclusions ; stability ; boundedness of solutions ; Lyapunov functions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract For Lipschitzian differential inclusions, we prove that the existence of suitable Lyapunov functions is necessary for uniform stability and uniform boundedness of solutions.
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    URL: http://dx.doi.org/10.1023/A:1008603707291
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  • 16
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    Stability and performance analysis of rate-based feedback flow controlled ATM networks (1998)
    Springer
    Queueing systems 29 (1998), S. 129-159 
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    ISSN: 1572-9443
    Keywords: rate-based feedback control ; ATM networks ; stability ; optimal algorithms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019127929282
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  • 17
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    On the stability of retrial queues (1997)
    Springer
    Queueing systems 26 (1997), S. 343-363 
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    ISSN: 1572-9443
    Keywords: retrial queues ; stability ; ergodicity ; renovation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: 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.
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    URL: http://dx.doi.org/10.1023/A:1019193527040
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  • 18
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    Multiwavelet approximation methods for pseudodifferential equations on curves. Stability and convergence analysis (1998)
    Springer
    Advances in computational mathematics 9 (1998), S. 145-171 
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    ISSN: 1572-9044
    Keywords: 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
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: 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.
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    URL: http://dx.doi.org/10.1023/A:1018977120831
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  • 19
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    Stability of Hypersurfaces with Constant $$r$$ -Mean Curvature (1997)
    Springer
    Annals of global analysis and geometry 15 (1997), S. 277-297 
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    ISSN: 1572-9060
    Keywords: mean curvature ; $$r$$ -mean curvature ; sphere ; stability ; stable
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006514303828
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    Stability Concepts in Topological Dynamics by Nonstandard Methods (1997)
    Springer
    Acta applicandae mathematicae 49 (1997), S. 35-54 
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    ISSN: 1572-9036
    Keywords: dynamical systems ; stability ; pseudo orbit tracing property ; nonstandard analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: 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.
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    URL: http://dx.doi.org/10.1023/A:1005840309425
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  • 21
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    Stability and Geometry of Third-Order Resonances in four-Dimensional Symplectic Mappings (1997)
    Springer
    Celestial mechanics and dynamical astronomy 67 (1997), S. 181-204 
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    ISSN: 1572-9478
    Keywords: Hamiltonian systems ; symplectic mappings ; normal forms ; resonances ; stability ; three degrees of freedom
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: 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.
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    URL: http://dx.doi.org/10.1023/A:1008288826727
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    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 
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    ISSN: 1572-9478
    Keywords: restricted three-body problem ; libration points ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: 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....
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    URL: http://dx.doi.org/10.1023/A:1008271021060
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    Long Time Stability for the Main Problem of Artificial Satellites (1997)
    Springer
    Celestial mechanics and dynamical astronomy 69 (1997), S. 317-330 
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    ISSN: 1572-9478
    Keywords: artificial satellite ; Nekhoroshev's theory ; normal form ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: 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.
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    URL: http://dx.doi.org/10.1023/A:1008277122375
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  • 24
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    Nonlinear Stability of the Lagrangian Libration Points in the Chermnykh Problem (1998)
    Springer
    Celestial mechanics and dynamical astronomy 70 (1998), S. 41-58 
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    ISSN: 1572-9478
    Keywords: three-body problem ; libration points ; stability ; normal forms.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: 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.
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    URL: http://dx.doi.org/10.1023/A:1008250207046
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    On a spherical integral transformation and sections of star bodies (1998)
    Springer
    Monatshefte für Mathematik 126 (1998), S. 117-124 
    Details
    ISSN: 1436-5081
    Keywords: 52A20 ; 52A22 ; star bodies ; spherical integral transformations ; convex bodies ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: 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.
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    Ethene hydroformylation on Co/SiO2 catalysts (1998)
    Springer
    Catalysis letters 53 (1998), S. 97-101 
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    ISSN: 1572-879X
    Keywords: ethene hydroformylation ; heterogeneous catalysts ; cobalt catalysts ; gas‐phase deposition ; dispersion ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: 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.
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    URL: http://dx.doi.org/10.1023/A:1019053805618
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    Preparation of model catalysts by laser interference nanolithography followed by metal cluster deposition (1998)
    Springer
    Catalysis letters 56 (1998), S. 1-6 
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    ISSN: 1572-879X
    Keywords: nanolithography ; model catalyst ; palladium ; copper ; stability ; spin-coating ; SEM ; AFM ; XPS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: 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.
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    URL: http://dx.doi.org/10.1023/A:1019080222823
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    On the rotating rod with variable cross section (1997)
    Springer
    Archive of applied mechanics 67 (1997), S. 447-456 
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    ISSN: 1432-0681
    Keywords: Key words rotation ; stability ; energy criterion ; variational analysis ; functional analysis ; eigenvalue problem
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: 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.
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    URL: http://dx.doi.org/10.1007/s004190050130
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    Autonomous Intelligent Cruise Control with Actuator Delays (1998)
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    Journal of intelligent and robotic systems 23 (1998), S. 27-43 
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    ISSN: 1573-0409
    Keywords: autonomous control ; actuator delays ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: 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.
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    Stable Quasicrystalline Ground States (1997)
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    Journal of statistical physics 88 (1997), S. 691-711 
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    ISSN: 1572-9613
    Keywords: Quasicrystals ; nonperiodic tilings ; classical lattice-gas models ; ground states ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: 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.
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    URL: http://dx.doi.org/10.1023/B:JOSS.0000015168.25151.22
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    Renormalization of the Chapman–Enskog Expansion: Isothermal Fluid Flow and Rosenau Saturation (1998)
    Springer
    Journal of statistical physics 91 (1998), S. 285-305 
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    ISSN: 1572-9613
    Keywords: Chapman–Enskog expansion ; Burnett equation ; Boltzmann equation ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: 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.
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    URL: http://dx.doi.org/10.1023/A:1023048322851
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    Stable Sampled-data Adaptive Control of Robot Arms Using Neural Networks (1997)
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    Journal of intelligent and robotic systems 20 (1997), S. 131-155 
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    ISSN: 1573-0409
    Keywords: robot adaptive control ; basis function-like networks ; stability ; discrete variable structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: 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.
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    Robust Regulator for Flexible-Joint Robots Using Integrator Backstepping (1998)
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    Journal of intelligent and robotic systems 22 (1998), S. 23-38 
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    ISSN: 1573-0409
    Keywords: robot dynamic model ; stiffness matrix ; constant disturbance ; integrator backstepping ; Liapunov functions ; Barbalat lemma ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: 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.
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    Forward Assembly Planning Based on Stability (1997)
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    Journal of intelligent and robotic systems 19 (1997), S. 411-436 
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    ISSN: 1573-0409
    Keywords: assembly planning ; stability ; robot ; forward ; operations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: 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.
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    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 
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    ISSN: 1572-8943
    Keywords: calcium sulphide ; gypsum ; oxidation ; phosphogypsum ; reduction ; stability ; thermogravimetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: 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.
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    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 
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    ISSN: 1572-8943
    Keywords: DSC ; NMR ; 8-quinolinol compounds ; TG-DTG ; stability ; thermal decomposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: 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.
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    Evaluation of the stability of substituted InF3 glasses by differential thermal analysis (1997)
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    Journal of thermal analysis and calorimetry 50 (1997), S. 807-814 
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    ISSN: 1572-8943
    Keywords: DTA ; stability ; substituted InF3 glasses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: 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.
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    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 
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    ISSN: 1573-4919
    Keywords: heart mitochondria ; lability ; muscle mitochondria ; oxidative phosphorylation ; stability ; taurine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: 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)
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    Resilience in the Dynamics of Economy-Environment Systems (1998)
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    Environmental and resource economics 11 (1998), S. 503-520 
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    ISSN: 1573-1502
    Keywords: biodiversity ; dynamics ; resilience ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Economics
    Notes: 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.
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    Coating of Sol Particles for Membrane Applications (1997)
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    Journal of sol gel science and technology 8 (1997), S. 523-527 
    Details
    ISSN: 1573-4846
    Keywords: UF membranes ; alumina ; zirconia coating ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: 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.
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    Coating of sol particles for membrane applications (1997)
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    Journal of sol gel science and technology 8 (1997), S. 523-527 
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    ISSN: 1573-4846
    Keywords: UF membranes ; alumina ; zirconia coating ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: 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.
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    A pseudospectral method for vorticity equations on spherical surface (1997)
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    Acta mathematicae applicatae sinica 13 (1997), S. 176-187 
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    ISSN: 1618-3932
    Keywords: Spherical surface ; pseudospectral method ; vorticity equations ; stability ; convergence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: 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.
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    Stability of linear time variant dynamic systems with multiple time delays (1998)
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    Acta mechanica Sinica 14 (1998), S. 274-282 
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    ISSN: 1614-3116
    Keywords: time delay ; stability ; frozen time approach ; retarded dynamic systems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract By means of the frozen time approach and the Kronecker product, two criteria of asymptotic stability are derived for the linear, time variant dynamic systems with either short time delays or with weak feedback involving arbitrary time delays, respectively. It is found that the asymptotic stability of these retarded dynamic systems is governed by the maximal and minimal singular values of the coefficient matrices and their time derivatives.
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    Periodic vibro-impacts and their stability of a dual component system (1997)
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    Acta mechanica Sinica 13 (1997), S. 366-376 
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    ISSN: 1614-3116
    Keywords: vibro-impact ; stability ; multiplicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The coexisting periodic impacting motions and their multiplicity of a kind of dual component systems under harmonic excitation are analytically derived. The stability condition of a periodic impacting motion is given by analyzing the propagation of small, arbitrary perturbation from that motion. In numerical simulations, the periodic impacting motions are classified according to the system states before and after an impact. The numerical results show that there exist many types of vibro-impacts and the bifurcation of periodic vibro-impacts is not smooth.
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    The stability of viscous liquid jets in a swirling gas (1998)
    Springer
    Acta mechanica Sinica 14 (1998), S. 226-233 
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    ISSN: 1614-3116
    Keywords: jet ; stability ; dispersion equation ; swirling gas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Based on the linear analysis of stability, a dispersion equation is deduced which delineates the evolution of a general 3-dimensional disturbance on the free surface of an incompressible viscous liquid jet injected into a gas with swirl. Here, the dimensionless parameterJ e is again introduced, in the meantime, another dimensionless parameterE called as circulation is also introduced to represent the relative swirling intensity. With respect to the spatial growing disturbance mode, the numerical results obtained from solving the dispersion equation reveal the following facts. First, at the same value ofE, in pace with the changing ofJ e , the variation of disturbance and the critical disturbance mode still keep the same characters. Second, the present results are the same as that of S.P. Lin whenJ e 〉1; but in the range ofJ e 〈1, it's no more the case, the swirl decreases the axisymmetric disturbance, yet increases the asymmetric disturbance, furthermore the swirl may make the character of the most unstable disturbance mode changed (axisymmetric or asymmetric); the above action of the swirl becomes much stronger whenJ e ≪1.
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    Progressive stable interpolation (1997)
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    Numerical algorithms 14 (1997), S. 343-359 
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    ISSN: 1572-9265
    Keywords: progressive interpolation ; stability ; spline ; shape parameters ; geometric continuity ; 41A05 ; 41A15 ; 65D05 ; 65D07
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract In this paper, we study several interpolating and smoothing methods for data which are known “progressively”. The algorithms proposed are governed by recurrence relations and our principal goal is to study their stability. A recurrence relation will be said stable if the spectral radius of the associated matrix is less than one. The iteration matrices depend on shape parameters which come either from the connection at the knots, or from the nature of the interpolant between two knots. We obtain various stability domains. Moving the parameters inside these domains leads to interesting shape effects.
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    Stable environments and fragile communities: does history determine the resilience of avian rain-forest communities to habitat degradation? (1997)
    Springer
    Biodiversity and conservation 6 (1997), S. 423-433 
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    ISSN: 1572-9710
    Keywords: Biodiversity ; stability ; rain-forest ; logging ; fragmentation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract By comparing results from studies on the response of bird communities to selective logging and fragmentation of tropical moist forest and assessing whether different local faunas are differently affected, this paper examines whether communities in areas of unstable ecoclimatic histories may be more robust to change than those which evolved in places which were paleoecologically stable. Studies on selective logging in Asia and forest fragmentation in Latin America do not confidently demonstrate differences in the resilience of bird communities between stable and unstable areas. However, studies of selective logging and forest fragmentation in Africa give much stronger evidence for differences in fragility of local avifaunas, which correspond to what would be predicted from the paleoecological stability. Unfortunately, the currently available studies do not provide a basis for rigorous testing of the hypothesis. Comparison is constrained by lack of suitable controls, incomparable census methods, inadequate description of the disturbance regimes, and differences in the intensity of disturbance. It is suggested that well coordinated studies in many different areas, with good and standardized documentation of many habitat variables, may have considerable importance.
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    Competing Models of Stability in Complex, Evolving Systems: Kauffman vs. Simon (1998)
    Springer
    Biology and philosophy 13 (1998), S. 541-554 
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    ISSN: 1572-8404
    Keywords: complex natural system ; stability ; evolvability ; decomposable hierarchy ; genetic network ; Random NK Boolean Network
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Philosophy
    Notes: Abstract I criticize Herbert Simon's argument for the claim that complex natural systems must constitute decomposable, mereological or functional hierarchies. The argument depends on certain assumptions about the requirements for the successful evolution of complex systems, most importantly, the existence of stable, intermediate stages in evolution. Simon offers an abstract model of any process that succeeds in meeting these requirements. This model necessarily involves construction through a decomposable hierarchy, and thus suggests that any complex, natural, i.e., evolved, system is constituted by a decomposable hierarchy. I argue that Stuart Kauffman's recent models of genetic regulatory networks succeed in specifying processes that could meet Simon's requirements for evolvability without requiring construction through a decomposable hierarchy. Since Kauffman's models are at least as plausible as Simon's model, Simon's argument that complex natural systems must constitute decomposable, mereological or functional hierarchies does not succeed.
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    On an inverse initial-boundary value problem for a one-dimensional hyperbolic system of differential equations (1997)
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    Acta mathematicae applicatae sinica 13 (1997), S. 33-44 
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    ISSN: 1618-3932
    Keywords: Inverse problem ; hyperbolic equations ; eigenvalue problem ; spectral function ; integral kernel ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract In this paper, the inverse boundary value problem of the hyperbolic system of first-order differential equations is discussed. The estimate of the solution and the quantitative analysis about its stability are obtained, and some stability criteria are established.
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    Pharmaceutical development of a parenteral lyophilized formulation of the investigational antitumor neuropeptide antagonist [Arg6, D-Trp7,9, MePhe8]-Substance P {6-11} (1998)
    Springer
    Investigational new drugs 16 (1998), S. 99-111 
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    ISSN: 1573-0646
    Keywords: Antagonist G ([Arg6, D-Trp7,9,,MePhe 8 ]-Substance P {6-11}) ; analytical characterization ; parenteral formulation ; stability ; oxidative degradation products
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract The aim of this study was to develop a stable parenteral dosage form for the investigational cytotoxic drug [Arg6, D-Trp7,9, MePhe8]-Substance P {6-11} (Substance P Antagonist G; Antagonist G). Antagonist G bulk drug was structurally and analytically characterized. The drug exhibits excellent aqueous solubility, although relatively poor aqueous stability characteristics. Lyophilization was, therefore, selected as the manufacturing process. Differential scanning calorimetry studies were conducted to determine the freeze-drying cycle parameters which resulted in a stable, lyophilized formulation of Antagonist G. The prototype, containing 50 mg Antagonist G per vial, was found to be the optimal formulation in terms of solubility, length of the freeze-drying cycle, stability, and dosage requirements in the planned phase I clinical trials. Quality control of the freeze-dried formulation showed that the manufacturing process does not change the integrity of Antagonist G. Shelf life studies demonstrated that the formulation is stable for at least 3 years, when stored at 2–8°C in a dark environment. Oxidative degradation products of Antagonist G were isolated and structurally characterized by mass spectrometry, nuclear magnetic resonance spectroscopy, and infrared spectroscopy.
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    The auto-adjustable damping method for solving nonlinear equations (1998)
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    Applied mathematics and mechanics 19 (1998), S. 163-168 
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    ISSN: 1573-2754
    Keywords: nonlinear equation ; stability ; Newton's method ; auto-adjustable damping method ; the vector of damping factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Mathematics , Physics
    Notes: Abstract The general approach for solving the nonlinear equations is linearizing the equations and forming various iterative procedures, then executing the numerical simulation. For the strongly nonlinear problems, the solution obtained in the iterative process is always difficult, even divergent due to the numerical instability. It can not fulfill the engineering requirements. Newton's method and its variants can not settle this problem. As a result, the application of numerical simulation for the strongly nonlinear problems is limited. An auto-adjustable damping method has been presented in this paper. This is a further improvement of Newton's method with damping factor. A set of vector of damping factor is introduced. This set of vector can be adjusted continuously during the iterative process in accordance with the judgement and adjustment. An effective convergence coefficient and quichening coefficient are employed to relax the restricted requirements for the initial values and to shorten the iterative process. Then, the numerical stability will be ensured for the solution of complicated strongly nonlinear equations. Using this method, some complicated strongly nonlinear heat transfer problems in airplanes and aeroengines have been numerically simulated successfully. It can be used for the numerical simulation of strongly nonlinear problems in engineering such as nonlinear hydrodynamics and aerodynamics, heat transfer and structural dynamic response etc.
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    Disturbances to a rotating fluid with a sphere moving along the axis of rotation (1998)
    Springer
    Applied mathematics and mechanics 19 (1998), S. 861-867 
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    ISSN: 1573-2754
    Keywords: rotating fluids ; motion of body ; small disturbances ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Mathematics , Physics
    Notes: Abstract In this paper, the disturbances to a uniformly rotating ideal fluid with a sphere moving steadily along the axis of rotation are analysed by using linearization theory, the equations of disturbance, pressure and disturbance stream function governing the stability of motion are derived based on the assumption that the flow is rotational symmetric. The equation of disturbance stream function is analysed with the method of normal modes, and the constraints on wave number and wave velocity of the nontrivial neutral disturbances are established and the exact expression of the neutral disturbances are obtained. The conclusion is drawn that three are three kinds of possible forms of neutral disturbances.
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    Bifurcations in Spherical MHD Models (1998)
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    Studia geophysica et geodaetica 42 (1998), S. 320-327 
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    ISSN: 1573-1626
    Keywords: MHD ; stability ; bifurcations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Physics
    Notes: Abstract A series of numerical studies on the behaviour of magnetic fields and motions in a spherical body of an electrically conducting incompressible fluid have been carried out. The magnetic field was assumed to be maintained by a given electromotive force inside the body and to continue as a potential field in outer space. In view of the motion an external forcing was taken into account, and boundary conditions were considered which correspond to a stress-free surface. The stability of several steady states has been studied as well as the evolutions starting from unstable states. In this paper a configuration with a poloidal magnetic field and a differential rotation, both symmetric about the same axis, is considered. This configuration is stable only for sufficiently small Hartmann numbers but evolves, if disturbed, in the case of larger Hartmann numbers toward a non-axisymmetric state. In this case the well-known symmetrization effect of differential rotation in magnetic fields is destroyed.
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    The stability in neural networks with interneuronal transmission delays (1998)
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    Applied mathematics and mechanics 19 (1998), S. 457-462 
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    ISSN: 1573-2754
    Keywords: neural networks ; equilibrium ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Mathematics , Physics
    Notes: Abstract In this paper, some sufficient conditions are obtained for the global asymptotic stability of the equilibrium of neural networks with interneuronal transmission delays of the type $$x'_i (t) = - b_i x_i (t) + \sum\limits_{j = 1}^n {\omega _{\ddot y} f_j (x_j (t - \tau _j )) + p_i (t 〉 0;i = 1,2, \cdots ,n)} $$
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    On the way to eternity; the success of an aquatic laboratory microecosystem (1997)
    Springer
    Aquatic ecology 31 (1997), S. 29-35 
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    ISSN: 1573-5125
    Keywords: Daphnia ; microcosm ; three compartment microecosystem ; threshold food concentration ; stability ; state space
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A microecosystem consisting of three subsystems roughly representing the trophic levels of autotrophs, herbivores and decomposers was developed. A recirculating flow of water connected the three subsystems. Analysis of the data over a period of 7500 days indicates that the system has remained in the same state and has the prospect of being ‘immortal’. The Daphnia population showed periods of large oscillations, but also long periods of almost constant numbers. External factors were responsible for the initiation of the oscillations. The threshold food level for population increase was lower than mostly is found for individual growth, indicating adaptation to low food concentrations.
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    Timed Petri Nets in Hybrid Systems: Stability and Supervisory Control (1998)
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    Discrete event dynamic systems 8 (1998), S. 137-173 
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    ISSN: 1573-7594
    Keywords: hybrid systems ; switched systems ; timed Petri nets ; stability ; supervisory control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract In this paper, timed Petri nets are used to model and control hybrid systems. Petri nets are used instead of finite automata primarily because of the advantages they offer in dealing with concurrency and complexity issues. A brief overview of existing results on hybrid systems that are based on Petri nets is first presented. A class of timed Petri nets named programmable timed Petri nets (PTPN) is then used to model hybrid systems. Using the PTPN, the stability and supervisory control of hybrid systems are addressed and efficient algorithms are introduced. In particular, we present sufficient conditions for the uniform ultimate boundness of hybrid systems composed of multiple linear time invariant plants which are switched between using a logical rule described by a Petri net. This paper also examines the supervisory control of a hybrid system in which the continuous state is transfered to a region of the state space in a way that respects safety specifications on the plant's discrete and continuous dynamics.
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    Some Ergodic Results on Stochastic Iterative Discrete Events Systems (1997)
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    Discrete event dynamic systems 7 (1997), S. 209-232 
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    ISSN: 1573-7594
    Keywords: Stochastic recurrence equations ; performance evaluation ; ergodicity ; stability ; subadditive ergodic theory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract This paper deals with the asymptotic behavior of the stochastic dynamics of discrete event systems. In this paper we focus on a wide class of models arising in several fields and particularly in computer science. This class of models may be characterized by stochastic recurrence equations in ℝK of the form T(n+1) = φ n+1(T(n)) where φ n is a random operator monotone and 1—linear. We establish that the behaviour of the extremas of the process T(n) are linear. The results are an application of the sub-additive ergodic theorem of Kingman. We also give some stability properties of such sequences and a simple method of estimating the limit points.
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    Modified Conjugate Gradient Method for the Solution of Ax=b (1998)
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    Journal of scientific computing 13 (1998), S. 173-183 
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    ISSN: 1573-7691
    Keywords: Modified conjugate gradient method ; conjugate gradient method ; Krylov space ; convergence rate ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract In this note, we examine a modified conjugate gradient procedure for solving $$A\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{x} = \underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{b}$$ in which the approximation space is based upon the Krylov space ( $$A\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{x} = \underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{b}$$ ) associated with $$\sqrt A$$ and $$\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{b}$$ . We show that, given initial vectors $$\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{b}$$ and $$\sqrt A \underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{b}$$ (possibly computed at some expense), the best fit solution in $$K^k \sqrt A ,\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{b}$$ can be computed using a finite-term recurrence requiring only one multiplication by A per iteration. The initial convergence rate appears, as expected, to be twice as fast as that of the standard conjugate gradient method, but stability problems cause the convergence to be degraded.
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    A New ADI Scheme for Solving Three-Dimensional Parabolic Differential Equations (1997)
    Springer
    Journal of scientific computing 12 (1997), S. 361-369 
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    ISSN: 1573-7691
    Keywords: Alternating-direction implicit ; difference scheme ; stability ; convergence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract A new alternating-direction implicit (ADI) scheme for solving three-dimensional parabolic differential equations has been developed based on the idea of regularized difference scheme. It is unconditionally stable and second-order accurate. Further, it overcomes the drawback of the Douglas scheme and is to be very well to simulate fast transient phenomena and to efficiently capture steady state solutions of parabolic differential equations. Numerical example is illustrated.
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    Splitting Methods for Three-Dimensional Transport Models with Interaction Terms (1997)
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    Journal of scientific computing 12 (1997), S. 215-231 
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    ISSN: 1573-7691
    Keywords: Transport models ; shallow water ; splitting methods ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract We investigate the use of splitting methods for the numerical integration of three-dimensional transport-chemistry models. In particular, we investigate various possibilities for the time discretization that can take advantage of the parallelization and vectorization facilities offered by multi-processor vector computers. To suppress wiggles in the numerical solution, we use third-order, upwind-biased discretization of the advection terms, resulting in a five-point coupling in each direction. As an alternative to the usual splitting functions, such as co-ordinate splitting or operator splitting, we consider a splitting function that is based on a three-coloured hopscotch-type splitting in the horizontal direction, whereas full coupling is retained in the vertical direction. Advantages of this splitting function are the easy application of domain decomposition techniques and unconditional stability in the vertical, which is an important property for transport in shallow water. The splitting method is obtained by combining the hopscotch-type splitting function with various second-order splitting formulae from the literature. Although some of the resulting methods are highly accurate, their stability behaviour (due to horizontal advection) is quite poor. Therefore we also discuss several new splitting formulae with the aim to improve the stability characteristics. It turns out that this is possible indeed, but the price to pay is a reduction of the accuracy. Therefore, such methods are to be preferred if accuracy is less crucial than stability; such a situation is frequently encountered in solving transport problems. As part of the project TRUST (Transport and Reactions Unified by Splitting Techniques), preliminary versions of the schemes are implemented on the Cray C98 4256 computer and are available for benchmarking.
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    A Generalized Peaceman–Rachford ADI Scheme for Solving Two-Dimensional Parabolic Differential Equations (1997)
    Springer
    Journal of scientific computing 12 (1997), S. 353-360 
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    ISSN: 1573-7691
    Keywords: Alternating-direction implicit ; difference scheme ; stability ; convergence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract A generalized Peaceman–Rachford alternating-direction implicit (ADI) scheme for solving two-dimensional parabolic differential equations has been developed based on the idea of regularized difference scheme. It is to be very well to simulate fast transient phenomena and to efficiently capture steady state solutions of parabolic differential equations. Numerical example is illustrated.
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    The Dynamics of Nonlinear Relaxation Labeling Processes (1997)
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    Journal of mathematical imaging and vision 7 (1997), S. 309-323 
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    ISSN: 1573-7683
    Keywords: relaxation labeling processes ; consistency ; growth transformations ; Liapunov functions ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract We present some new results which definitively explain thebehavior of the classical, heuristic nonlinear relaxation labelingalgorithm of Rosenfeld, Hummel, and Zucker in terms of theHummel-Zucker consistency theory and dynamical systems theory. Inparticular, it is shown that, when a certain symmetry condition is met,the algorithm possesses a Liapunov function which turns out to be (thenegative of) a well-known consistency measure. This follows almostimmediately from a powerful result of Baum and Eagon developed in thecontext of Markov chain theory. Moreover, it is seen that most of theessential dynamical properties of the algorithm are retained when thesymmetry restriction is relaxed. These properties are also shown tonaturally generalize to higher-order relaxation schemes. Someapplications and implications of the presented results are finallyoutlined.
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    Constrained Learning in Neural Networks: Application to Stable Factorization of 2-D Polynomials (1998)
    Springer
    Neural processing letters 7 (1998), S. 5-14 
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    ISSN: 1573-773X
    Keywords: constrained learning ; factorization ; feedforward networks ; IIR filters ; polynomials ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract Adaptive artificial neural network techniques are introduced and applied to the factorization of 2-D second order polynomials. The proposed neural network is trained using a constrained learning algorithm that achieves minimization of the usual mean square error criterion along with simultaneous satisfaction of multiple equality and inequality constraints between the polynomial coefficients. Using this method, we are able to obtain good approximate solutions for non-factorable polynomials. By incorporating stability constraints into the formalism, our method can be successfully used for the realization of stable 2-D second order IIR filters in cascade form.
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    Functional responses of adaptive consumers and community stability with emphasis on the dynamics of plant-herbivore systems (1997)
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    Evolutionary ecology 11 (1997), S. 773-784 
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    ISSN: 1573-8477
    Keywords: adaptive behaviour ; community dynamics ; functional response ; regulation ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A comparatively recent focus in consumer–resource theory has been the examination of whether adaptive foraging by consumers, manifested through the functional response, can stabilize consumer–resource dynamics. We offer a brief synthesis of progress on this body of theory and identify the conditions likely to lead to stability. We also fill a gap in our understanding by analysing the potential for adaptively foraging herbivores, which are constrained by time available to feed and digestive capacity, to stabilize dynamics in a single-herbivore/two-plant resource system. Because foraging parameters of the adaptive functional response scale allometrically with herbivore body size, we parameterized our model system using published foraging data for an insect, a small mammal and a large mammal spanning four orders of magnitude in body size, and examined numerically the potential for herbivores to stabilize the consumer–resource interactions. We found in general that the herbivore–plant equilibrium will be unstable for all biologically realistic herbivore population densities. The instability arose for two reasons. First, each herbivore exhibited destabilizing adaptive consumer functional responses (i.e. density-independent or inversely density-dependent) whenever they selected a mixed diet. Secondly, the numerical response of herbivores, based on our assumption of density-independent herbivore population growth, results in herbivores reaching densities that enable them to exploit their resource populations to extinction. Our results and those of studies we reviewed indicate that, in general, adaptive consumers are unlikely to stabilize the dynamics of consumer–resource systems solely through the functional response. The implications of this for future work on consumer–resource theory are discussed.
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    On the Global Dynamics of a Controlled Viscous Burgers' Equation (1998)
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    Journal of dynamical and control systems 4 (1998), S. 457-519 
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    ISSN: 1573-8698
    Keywords: Boundary control ; nonlinear distributed parameter system ; center manifold theorem ; stability ; local attractors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract In this paper we consider a boundary control problem for a forced Burgers' equation in a Hilbert state space consisting of square integrable functions on a finite interval. Our first main result consists in proving the global in time existence of solutions of the closed loop boundary control system for arbitrary L 2 initial data and quite general forcing terms (disturbances). For the unforced problem, our main interest is in stability of equilibria, while for the forced problem we are interested in steady state behavior of solutions. We note that the uncontrolled (open loop), unforced problem is not asymptotically stable on L 2. However, for positive gains we show that the unforced closed loop system is globally Lyapunov stable and locally exponentially stable. In addition, for nonzero stationary forcing, we show that there is a local absorbing ball and that the corresponding nonlinear semigroup is compact for all t 〉 0. Using this fact, we are able to deduce several consequences regarding the existence and properties of local attractors. Our method of proof is based on a systematic investigation of the smoothing properties of the controlled dynamics. In particular we establish various regularity results for the dynamics of the closed loop system.
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    Control of Discrete Fuzzy Systems: Uncertainty and Guaranteed Performance (1998)
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    Dynamics and control 8 (1998), S. 83-106 
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    ISSN: 1573-8450
    Keywords: fuzzy modeling ; robust control ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Robust control designs for a discrete Takagi and Sugeno (T-S) fuzzy model are proposed. The T-S fuzzy model contains (possibly fast) time-varying uncertainty. First, a switching-type robust control is shown to stabilize the T-S fuzzy model asymptotically. Second, a saturation-type robust control is shown to render the T-S model practically stable. In both designs, only the bound of uncertainty is needed. The effectiveness of proposed designs is analyzed rigorously and illustrated by simulations.
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    Almost-periodic solutions to systems of differential equations with fast and slow time in the degenerate case (1998)
    Springer
    Mathematical notes 63 (1998), S. 396-400 
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    ISSN: 1573-8876
    Keywords: ordinary differential equations ; fast and slow time ; periodic solutions ; existence ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract We consider a system of ordinary first-order differential equations. The right-hand sides of the system are proportional to a small parameter and depend almost periodically on fast time and periodically on slow time. With this system, we associate the system averaged over fast time. We assume that the averaged system has a structurally unstable periodic solution. We prove a theorem on the existence and stability of almost periodic solutions of the original system.
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    A generalization of the Tikhonov theorem for singularly perturbed differential inclusions (1997)
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    Journal of dynamical and control systems 3 (1997), S. 291-319 
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    ISSN: 1573-8698
    Keywords: 34D15 ; 34E15 ; 34A60 ; 93C73 ; 93D20 ; 49N99 ; Singular perturbation ; differential inclusion ; control systems ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract We study the continuity properties of the bundle of solutions to a differential inclusion subject to a singular perturbation, i.e., with respect to a scalar parameter ɛ multiplying a part of the derivatives. We give conditions under which every solution of the singularly perturbed inclusion is close, in a certain sense and for a sufficiently small ɛ, to a solution of the degenerate inclusion obtained for ɛ=0. These conditions include both stability and structural requirements (the later having no counterpart in the case of a differential equation). The main result obtained generalizes the well-known Tikhonov theorem for singularly perturbed differential equations.
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    Isothermal and Nonisothermal Decomposition of Thymopentin and Its Analogs in Aqueous Solution (1998)
    Springer
    Pharmaceutical research 15 (1998), S. 1702-1707 
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    ISSN: 1573-904X
    Keywords: stability ; isothermal ; nonisothermal ; thymopentin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The degradation kinetics of thymopentin (RKDVY) and its analogs (RKDVW and RPDVY) in aqueous solution was studied by isothermal and nonisothermal methods. Methods. The isothermal decomposition of thymopentin and its analogs was investigated as a function of pH (2−10), temperature (37, 57, and 80°C) and ionic strength (μ = 0.02 to 1). Nonisothermal decomposition studies were performed using a linear temperature programmer. The temperature increasing rate was set to 0.25°C per hour and the temperature interval varied from 40 to 88°C. Results. The decomposition of thymopentin and its analogs followed first order kinetics. The dependence of the rate constant on temperature followed a linear Arrhenius plot. This indicated that the degradation mechanism of thymopentin and its analogs might be the same within the temperature range studied. The energies of activation were found to be in close agreement for the isothermal and nonisothermal studies, suggesting that the nonisothermal studies may save considerable amount of time in the early stages of drug development. The logK-pH profile of thymopentin suggests that maximum stability is achieved in the pH range of 6−8. Conclusions. These results indicate that the nonisothermal methodology provides an attractive alternative to isothermal methods, as it requires a much lower amount of both material and time, to determine the peptide stability and to estimate the shelf-life for peptide pharmaceutical preparations.
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    URL: http://dx.doi.org/10.1023/A:1011952511091
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    The Stability of Recombinant Human Growth Hormone in Poly(lactic-co-glycolic acid) (PLGA) Microspheres (1997)
    Springer
    Pharmaceutical research 14 (1997), S. 420-425 
    Details
    ISSN: 1573-904X
    Keywords: growth hormone ; stability ; poly(lactic-co-glycolic acid) ; microencapsulation ; degradation ; sustained release
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The development of a sustained release formulation for recombinant human growth hormone (rhGH) as well as other proteins requires that the protein be stable at physiological conditions during its in vivo lifetime. Poly(lactic-co-glycolic acid) (PLGA) microspheres may provide an excellent sustained release formulation for proteins, if protein stability can be maintained. Methods. rhGH was encapsulated in PLGA microspheres using a double emulsion process. Protein released from the microspheres was assessed by several chromatrographic assays, circular dichroism, and a cell-based bioassay. The rates of aggregation, oxidation, diketopiperazine formation, and deamidation were then determined for rhGH released from PLGA microspheres and rhGH in solution (control) during incubation in isotonic buffer, pH 7.4 and 37°C. Results. rhGH PLGA formulations were produced with a low initial burst (〈20%) and a continuous release of rhGH for 30 days. rhGH was released initially from PLGA microspheres in its native form as measured by several assays. In isotonic buffer, pH 7.4 and 37°C, the rates of rhGH oxidation, diketopiperazine formation, and deamidation in the PLGA microspheres were equivalent to the rhGH in solution, but aggregation (dimer formation) occured at a slightly faster rate for protein released from the PLGA microspheres. This difference in aggregation rate was likely due to the high protein concentration used in the encapsulation process. The rhGH released was biologically active throughout the incubation at these conditions which are equivalent to physiological ionic strength and pH. Conclusions. rhGH was successfully encapsulated and released in its fully bioactive form from PLGA microspheres over 30 days. The chemical degradation rates of rhGH were not affected by the PLGA microspheres, indicating that the internal environment of the microspheres was similar to the bulk solution. After administration, the microspheres should become fully hydrated in the subcutaneous space and should experience similar isotonic conditions and pH. Therefore, if a protein formulation provides stability in isotonic buffer, pH 7.4 and 37°C, it should allow for a safe and efficacious sustained release dosage form in PLGA microspheres.
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    Solvent Effects on the Solubility and Physical Stability of Human Insulin-Like Growth Factor I (1997)
    Springer
    Pharmaceutical research 14 (1997), S. 606-612 
    Details
    ISSN: 1573-904X
    Keywords: hIGF-I ; benzyl alcohol ; preferential interaction ; stability ; preservative
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The solubility and physical stability of human Insulin-like Growth Factor I (hIGF-I) were studied in aqueous solutions with different excipients. Methods. The solubility of hIGF-I was determined by UV-absorption and quantification of light blocking particles. The physical stability of hIGF-I was studied with differential scanning calorimetry (DSC) and circular dichroism (CD) spectroscopy. Results. Human IGF-I precipitated at low temperature in the presence of 140 mM benzyl alcohol and 145 mM sodium chloride. CD data showed that the tertiary structure of hIGF-I during these conditions was perturbed compared to that in 5 mM phosphate buffer. In the presence of benzyl alcohol 290 mM mannitol stabilized hIGF-I. Sodium chloride or mannitol by themselves had no effect on either the solubility or the tertiary structure. Benzyl alcohol was attracted to hIGF-I, whereas sodium chloride was preferentially excluded. The attraction of benzyl alcohol was reinforced by sodium chloride leading to salting-out of hIGF-I. The CD-data indicated interactions of benzyl alcohol with phenylalanine in hIGF-I. Thermal denaturation of hIGF-I occurred in all solutions with sodium chloride, whereas mannitol or benzyl alcohol had no effect on the thermal stability. The thermal stability of hlGF-I was thus decreased in 145 mM sodium chloride although it was excluded from hIGF-I. Conclusions. The self-association and thermal aggregation of hIGF-I is driven by hydrophobic interactions. Benzyl alcohol is attracted to hIGF-I and induces changes in the tertiary structure causing hydrophobic attraction of the protein at low temperatures.
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    Diffusion of innovations in globally stable Walrasian equilibrium (1997)
    Springer
    Journal of economics 66 (1997), S. 1-22 
    Details
    ISSN: 1617-7134
    Keywords: diffusion of innovations ; Walrasian equilibrium ; stability ; O31
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract When all products in the economy are weak gross substitutes, preferences are homothetic, and firms face menu costs then all prices in an industry move together at the same rate. In the closed-loop Nash noncooperative equilibrium, all firms invest in productivity and reduce real prices. As a result, in the case of quadratic menu costs, the outputs of industries and the economy go up along S-shaped time paths characteristic of diffusion of innovations.
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    A dynamic Stackelberg model with production-adjustment costs (1997)
    Springer
    Journal of economics 66 (1997), S. 271-282 
    Details
    ISSN: 1617-7134
    Keywords: Stackelberg model ; dynamic oligopoly ; stability ; C62 ; C73 ; D43
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract We investigate the (dynamic) stability of a stackelberg oligopoly model of a market of a homogeneous good, with output competition, one Stackelberg leader and a number of identical followers. We assume that each firm incurs quadratic production-adjustment costs if it changes its output. We present a simple necessary and sufficient condition for stability of the model. Using the condition, we compare the stability of this model with the stability of two related Cournot models in which all firms present are followers. It turns out that the Stackelberg model is “more stable” than these two Cournot models.
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    Developing elite durum wheat landrace selections (composites) for Ethiopian peasant farm use: Raising productivity while keeping diversity alive (1998)
    Springer
    Euphytica 102 (1998), S. 323-328 
    Details
    ISSN: 1573-5060
    Keywords: Triticum turgidum ; farmers' varieties ; genetic diversity ; composite ; stability ; durum wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The Ethiopian peasant farms are characterized by highly varied micro-environments differing in characteristics such as topography, soil type, water, temperature and fertility. The bulk of the durum wheat planting material currently in use on these farms is largely represented by traditional farmers' varieties/landraces. These traditional farmers' varieties/landraces generally, are stable but low yielding, and often fail to adequately meet the level of productivity essential for production beyond subsistence level, unless they are enhanced to improve their competitiveness with modern varieties in respect to yield. Improving the productivity of landraces, while maintaining an appreciable level of genetic diversity is crucial to yield stability. This could be achieved by developing composites that are formed by bulking together three or more potentially high yielding spikes (agrotypes) that vary for various morphologic and agronomic characteristics, but due to their similarity in plant height, maturity, glume color and seed color give the composite a uniform field appearance like a modern variety.
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    Joint regression vs AMMI analysis of genotype-environment interactions for cereals in Italy (1997)
    Springer
    Euphytica 94 (1997), S. 53-62 
    Details
    ISSN: 1573-5060
    Keywords: adaptation ; AMMI ; cereals ; genotype-environment interaction ; joint regression ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Joint regression and Additive Main effects and Multiplicative Interaction (AMMI) models were compared for i) capacity of describing genotype-location (GL) and genotype-environment (GE) interaction effects (environments = location-season combinations), assessed in terms of estimated variance of heterogeneity of genotype regressions and of the sum of the variances of significant interaction principal component (PC) axes, and ii) repeatability between cropping seasons of measures of genotype stability across locations. These measures were Finlay and Wilkinson's regression coefficient for joint regression, and the Euclidean distance from the origin of significant interaction PC axes (D) and the absolute value of PC 1 score (| PC 1 |) for AMMI. Shukla's stability variance (σsup2;) was considered in addition. The study included three data sets for durum wheat, two for maize and one each for bread wheat and oat. Relationships between climatic variables and GL interaction occurrence were also assessed. AMMI proved distinctly more valuable in six data sets for description of GE effects and in four for description of GL effects over seasons. Its superiority was not crop-specific and tended to occur when more, distinct environmental constraints affected genotype responses. When both methods were appropriate, they provided a similar ordination of sites and genotypes for GL effects. The models that adequately described GL interaction over seasons generally provided also stability measures that were moderately repeatable between seasons. D was better repeatable than | PC 1 | and σ& 2; in a few cases. Ordination of locations on GL interaction PC 1 tended to be consistent both between wheat and between maize data sets having either no seasons or no genotypes in common.
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    Do body and fin form affect the abilities of fish to stabilize swimming during maneuvers through vertical and horizontal tubes? (1998)
    Springer
    Environmental biology of fishes 53 (1998), S. 365-371 
    Details
    ISSN: 1573-5133
    Keywords: Carassius auratus ; Metynnis hypsauchen ; Pterophyllum scalare ; goldfish ; angelfish ; silver dollar ; swimming ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Goldfish, Carassius auratus, silver dollar, Metynnis hypsauchen, and angelfish, Pterophyllum scalare were induced to swim through narrow vertical and horizontal tubes ranging in length from 0 to 20 cm (approximately 0 to 3 times total fish length, FL). The ability to stabilize the body while negotiating these confined spaces was quantified as (1) the minimum width of vertical (wv) and horizontal (wh) tubes traversed, where width is the smaller cross-sectional dimension of the tube, (2) the ratio wv/wh, and (3) transit speed through the tubes. Tube width was expressed as relative width, obtained by dividing tube width by fish length. Minimum relative widths traversed increased from 0.15 to 0.19 in the order silver dollar 〉 angelfish 〉 goldfish for vertical tubes and from 0.17 to 0.18 in the order goldfish=silver dollar 〉 angelfish for horizontal tubes. wv/wh increased from 0.91 to 1.10 in the order silver dollar=angelfish 〉 goldfish. Minimum tube widths generally increased with tube length for vertical tubes. Although significant differences in relative minimum widths among species were found, these were small. In contrast, for horizontal tubes, there was no significant effect of tube length on minimum tube width for any species. Large differences were found in transit speed. Transit speed generally decreased as the tube length increased. The slope of the relationship between transit speed and tube length varied among species generally increasing from − 0.41 to − 1.16 for horizontal tubes in the order goldfish 〉 silver dollar 〉 angelfish and from − 0.42 to − 1.07 in the order silver dollar 〉 goldfish 〉 angelfish for vertical tubes. As a result, goldfish usually took longest to traverse tubes of zero length but the shortest time to traverse the longest tubes. In contrast, angelfish traversed short tubes in the least time and long tubes in the greatest time. Deeper bodied angelfish swam slowly and traversed tubes with difficulty because they required experience during each trial to replace median and paired fin with body and caudal fin swimming. According to our data, goldfish were best able to swim in confined spaces.
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    Formation and properties of HCO-10 vesicles (1997)
    Springer
    Colloid & polymer science 275 (1997), S. 155-161 
    Details
    ISSN: 1435-1536
    Keywords: Key words HCO-10 ; vesicles ; encapsulation ; stability ; solubilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  The characteristics of poly(oxyethylene) hydrogenated caster oil ether (HCO-10) vesicles were studied for the standpoints of encapsulation efficiency, stability, solubilization and permeability or barrier efficiency. The vesicles of 5% HCO-10 had 6.24% of calcein-entrapment efficiency and 240 nm of mean diameter. The stability of HCO-10 vesicle suspensions was dependent on their concentrations. In the vesicle suspensions of 10% HCO-10 or more, both the size of the vesicles and the fluidity of the suspensions obviously varied with incubation time, indicating that a flocculation occurred; whereas, the vesicle suspension of 5% HCO-10 was relatively stable. The solubilization process of HCO-10 vesicles by SDS was similar to that of EggPC liposomes. The rate constants for permeation of Cl ion and calcein were 2.46×10-3 s-1 and 5.79×10-5 s-1, respectively, suggesting that HCO-10 vesicles possessed some barrier potential for Cl ion and calcein although they were smaller than those of liposomes. Furthermore, the efflux of the solute such as calcein from HCO-10 vesicles was maximum at 37 °C, where the vesicle membrane was presumably destabilized by dehydration of EOs in HCO-10 molecules.
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    The synthesis of polymer suspension with narrow particle size distribution for immunochemical investigations (1998)
    Springer
    Colloid & polymer science 276 (1998), S. 1068-1077 
    Details
    ISSN: 1435-1536
    Keywords: Key words Heterophase polymerization ; emulsion ; polymer particle ; stability ; styrene conversion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  Heterophase polymerization of styrene in the presence of di-p-tolyl-o-carbalkoxyphenylcarbinol (DTC) soluble in monomer and insoluble in water, as stabilizer, was investigated. The factors affecting polymer particle diameter, their size distribution and stability were investigated. It was suggested that polymer particles are formed from monomer droplets. The polystyrene suspension with narrow particle size distribution synthesized in the presence of DTC, was used for immunochemical research.
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    The behavior of ferric oxide hydrosols in the presence of urea (1997)
    Springer
    Colloid & polymer science 105 (1997), S. 38-40 
    Details
    ISSN: 1435-1536
    Keywords: α-haematite hydrosols ; stability ; urea ; ionic adsorption sequence ; water structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The effect of urea on the stability of α-haematite hydrosols in the presence of various monovalent ions was studied on each side of the pzc (pH 8.2) by measurements of the critical coagulation concentration (CCC) of the hydrosol. It was observed that for pHs lower than the pzc, the effect of urea depends strongly on the nature of coagulating ion and on the pH:The CCC values of IO 3 − increases with urea concentrations but those of ClO 4 − and Cl− decreases. For pHs higher than the pzc, an inversion of the cationic adsorption sequence was observed. This behavior is in a good agreement with the well-known action of urea on the structure of water and also with the general property of the α-haematite water interface.
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    Stability of viscoelastic flow around periodic arrays of cylinders (1997)
    Springer
    Rheologica acta 36 (1997), S. 367-383 
    Details
    ISSN: 1435-1528
    Keywords: Viscoelastic flow ; arrays of cylinders ; stability ; porous media
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract Low Reynolds number flow of Newtonian and viscoelastic Boger fluids past periodic square arrays of cylinders with a porosity of 0.45 and 0.86 has been studied. Pressure drop measurements along the flow direction as a function of flow rate as well as flow visualization has been performed to investigate the effect of fluid elasticity on stability of this class of flows. It has been shown that below a critical Weissenberg number (Wec), the flow in both porosity cells is a two-dimensional steady flow, however, pressure fluctuations appear above Wec which is 2.95±0.25 for the 0.45 porosity cell and 0.95±0.08 for the higher porosity cell. Specifically, in the low porosity cell as the Weissenberg number is increased above Wec a transition between a steady two-dimensional to a transient three-dimensional flow occurs. However, in the high porosity cell a transition between a steady two-dimensional to a steady three-dimensional flow consisting of periodic cellular structures along the length of the cylinder in the space between the first and the second cylinder occurs while past the second cylinder another transition to a transient three-dimensional flow occurs giving rise to time- dependent cellular structures of various wavelengths along the length of the cylinder. Overall, the experiments indicate that viscoelastic flow past periodic arrays of cylinders of various porosities is susceptible to purely elastic instabilities. Moreover, the instability observed in lower porosity cells where a vortex is present between the cylinders in the base flow is amplifieds spatially, that is energy from the mean flow is continuously transferred to the disturbance flow along the flow direction. This instability gives rise to a rapid increase in flow resistance. In higher porosity cells where a vortex between the cylinders is not present in the base flow, the energy associated with the disturbance flow is not greatly changed along the flow direction past the second cylinder. In addition, it has been shown that in both flow cells the instability is a sensitive function of the relaxation time of the fluid. Hence, the instability in this class of flows is a strong function of the base flow kinematics (i.e., curvature of streamlines near solid surfaces), We and the relaxation time of the fluid.
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    Stability of viscoelastic flow around periodic arrays of cylinders (1997)
    Springer
    Rheologica acta 36 (1997), S. 367-383 
    Details
    ISSN: 1435-1528
    Keywords: Key words Viscoelastic flow ; arrays of cylinders ; stability ; porous media
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract Low Reynolds number flow of Newtonian and viscoelastic Boger fluids past periodic square arrays of cylinders with a porosity of 0.45 and 0.86 has been studied. Pressure drop measurements along the flow direction as a function of flow rate as well as flow visualization has been performed to investigate the effect of fluid elasticity on stability of this class of flows. It has been shown that below a critical Weissenberg number (We c ), the flow in both porosity cells is a two-dimensional steady flow, however, pressure fluctuations appear above We c which is 2.95±0.25 for the 0.45 porosity cell and 0.95±0.08 for the higher porosity cell. Specifically, in the low porosity cell as the Weissenberg number is increased above We c a transition between a steady two-dimensional to a transient three-dimensional flow occurs. However, in the high porosity cell a transition between a steady two-dimensional to a steady three-dimensional flow consisting of periodic cellular structures along the length of the cylinder in the space between the first and the second cylinder occurs while past the second cylinder another transition to a transient three-dimensional flow occurs giving rise to time- dependent cellular structures of various wavelengths along the length of the cylinder. Overall, the experiments indicate that viscoelastic flow past periodic arrays of cylinders of various porosities is susceptible to purely elastic instabilities. Moreover, the instability observed in lower porosity cells where a vortex is present between the cylinders in the base flow is amplified spatially, that is energy from the mean flow is continuously transferred to the disturbance flow along the flow direction. This instability gives rise to a rapid increase in flow resistance. In higher porosity cells where a vortex between the cylinders is not present in the base flow, the energy associated with the disturbance flow is not greatly changed along the flow direction past the second cylinder. In addition, it has been shown that in both flow cells the instability is a sensitive function of the relaxation time of the fluid. Hence, the instability in this class of flows is a strong function of the base flow kinematics (i.e., curvature of streamlines near solid surfaces), We and the relaxation time of the fluid.
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    Money demand stability: Evidence from Spain (1998)
    Springer
    Empirical economics 23 (1998), S. 387-400 
    Details
    ISSN: 1435-8921
    Keywords: Money demand ; cointegration ; stability ; regime shift ; E41 ; C22
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: 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.
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    A reaction-diffusion equation for a cyclic system with three components (1997)
    Springer
    Journal of statistical physics 87 (1997), S. 1145-1164 
    Details
    ISSN: 1572-9613
    Keywords: Fisher-Kolmogorov equation ; traveling fronts ; fixed points ; population dynamics ; bifurcations ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The one-dimensional reaction-diffusion equations for the process (D) $$A + B \to 2A,B + C \to 2B,C + A \to 2C$$ are extended to include the counteracting reactions (R) $$A + 2B \to 3B,B + 2C \to 3C,C + 2A \to 3A$$ which have a reaction rate α relative to the direct process (D). This process can be seen as a three-component version of the reaction which is described by the Fisher-Kolmogorov equation. The fixed points of the equations are studied as a function of α. It is shown that the equations admit solutions which consist of a series of traveling fronts. Other solutions exist which are traveling periodic waves. A very remarkable fact is that for these waves exact expressions can be constructed.
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    Small-Angle Neutron Scattering Studies of Vesicle Stability (1998)
    Springer
    International journal of thermophysics 19 (1998), S. 461-470 
    Details
    ISSN: 1572-9567
    Keywords: small-angle neutron scattering ; stability ; vesicles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Small-angle neutron scattering (SANS) was used to investigate the structure of mixed colloids of egg yolk phosphatidylcholine (EYPC) with the bile salt, cholylglycine (CG), in D2O as a function of pressure (P) and temperature (T). At atmospheric pressure, the system forms an isotropic phase of mixed, single-bilayer vesicles (SLVs). Increasing the external hydrostatic pressure brought about significant changes in particle morphology. At T=25°C, application of a pressure of 3.5 MPa resulted in collapse of the SLVs. A further increase in P, up to 51.8 MPa, resulted in a transition from a phase of ordered (stacked), collapsed vesicles to one of stacked, ribbon-like particles. A similar collapse of the vesicles was observed at a higher temperature (T=37°C) with increasing P, but at this temperature, no ribbon phase was found at the highest pressure explored.
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    Properties of Optical Phase-Locked Loop Based on Four Wave Mixing in Semiconductor Laser Amplifiers (1998)
    Springer
    International journal of infrared and millimeter waves 19 (1998), S. 1721-1734 
    Details
    ISSN: 1572-9559
    Keywords: optical phase-locked loop ; stability ; phase jitter ; four-wave mixing ; semiconductor laser amplifier
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In this paper, the properties of the optical phase-locked loop(PLL) based on the four-wave mixing in the semiconductor laser amplifiers (SLAs) are discussed. The components that achieve the function of detecting the bit phase of the input optical signal are concerned and discussed in detail together as a function module named as the optical bit phase detector referred to the general electronic PLL. Therefore, most of the properties of the optical PLL can be analyzed by applying the general phase-locked theory. Here the stability of the optical PLL is discussed. It's shown that the variance of input signal power in the practical application will cause optical PLL system unstable because of its long loop delay. The influence on the output phase jitter of the optical PLL is also investigated.
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    Seeding date effects on rough rice yield and head rice and selection for stability (1998)
    Springer
    Euphytica 102 (1998), S. 151-161 
    Details
    ISSN: 1573-5060
    Keywords: Oryza sativa ; head rice ; seeding date ; rice ; rough rice yield ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The rice (Oryza sativa L.) crop in Arkansas is seeded from late March through early June each year. Farmers need new rice cultivars that not only produce both high rough rice yields and high head rice across this range of seeding dates but do so consistently. Thus, a seeding date study was conducted during 1994 and 1995 at Stuttgart, Arkansas, to study seeding date effects on rough rice yield and head rice and selection for stability. Fourteen rice cultivars were seeded at five dates ranging from late March through mid-June. Kang's yield-stability statistic was used to select cultivars for both high rough rice yields and high head rice as well as stability for both traits. Plant stands from March seedings of each year were significantly lower than for the later seeding dates. Maturity (days to 50 percent heading) was extended at the early seeding dates. Some rice cultivars, such as ‘LaGrue’, had lower and more variable head rice when seeded early. In the June seeding dates each year, ‘Kaybonnet’ produced rough rice yields that were more consistent with yields when planted at the earlier planting dates. ‘Bengal’, ‘Cypress’, ‘Kaybonnet’, and ‘Newbonnet’ were cultivars selected by Kang's stability statistic, which was targeted to select cultivars with stable, high rough rice yields and stable, high head rice. The validity of using Kang's yield-stability statistic for cultivar selection is also evident empirically by the adaptation and wide use of these four cultivars by southern U.S. rice producers. These results indicate that seeding date studies and stability analyses would be useful tools for rice breeders to identify cultivars that will be readily adapted and grown by rice producers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018344615296
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    Breeding for yield and quality in durum wheat (1998)
    Springer
    Euphytica 100 (1998), S. 15-18 
    Details
    ISSN: 1573-5060
    Keywords: biparental mating ; stability ; Triticum durum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Three populations of an intervarietal durum wheat cross IWP5308/PDW208, F5, F5BIP1 (population derived after intermating in F2) and F5BIP2 (population derived after intermating in BIPF1), were evaluated under three different agronomic environments for mean performance and stability of genotypes for grain yield, yield components and protein content. Though the biparental progenies indicated a higher mean performance, they did not differ significantly from progenies of the pedigree method for almost all characters. The biparental progenies, however, produced a higher number of stable genotypes for grain yield per plant, grains per ear and protein content. The F5 population had a higher number of stable genotypes for 1000 grain weight and number of tillers per plant. The BIP progenies also had a higher number of genotypes with above average mean performance, and many were significantly higher than the checks WH896 and WH542, compared with F5 progenies. Hence, in spite of high G x E interactions, the use of cycles of biparental mating and selection of top yielding lines on the basis of yield components can enable selection of stable genotypes with high protein content. Number of tillers per plant and 1000 grain weight were the yield component characters which made maximum contribution to phenotypic stability of the genotypes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018335402010
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    Stability of performance of tetraploid wheat landraces in the Ethiopian highland (1998)
    Springer
    Euphytica 102 (1998), S. 301-308 
    Details
    ISSN: 1573-5060
    Keywords: adaptation ; correlations ; genotype-environment interaction ; landraces ; performance ; stability ; tetraploid wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Plant breeding has always been concerned with genotype-environment interaction. Normally high and stable performance are desirable attributes of cultivars. However, this is practically difficult to achieve where environmental variations are high and unpredictable and significant genotype-environment interactions occur. Stability of performance of 13 landraces evaluated at 4 different locations for 3 years in the highlands of Ethiopia was investigated. The testing locations have different climatic and edaphic conditions providing the conditions necessary for the assessment of stability. Stability parameters like b, s2d, s2, r2 and cv which are in common use were employed. Grain yield and 1000-kernel weight were the agronomic traits considered for the stability analysis. There were differences in the ranks of genotypes across the locations. Significant main environmental as well as interaction effects were observed showing the importance of genotype-environment interaction in both traits. Many of the landraces evaluated are rated as stable for these traits within the environmental conditions prevailing in these highland locations. Genotypes with specific adaptation to poor and favourable conditions were also identified. Certain genotypes showed similar manners of adaptation and stability for both of the traits. Grain yield showed low correlations with the stability parameters showing the possibility of attaining high yield and stability. Correlations between the stability parameters were mainly positive and significant for grain yield. Only a few of these correlations were found to be significant for kernel weight. The good adaptability of landraces should be exploited in the improvement of their yield potential.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018361309207
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  • 89
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    Isozyme polymorphism of Rosa spp. and cultivar identification (1997)
    Springer
    Euphytica 98 (1997), S. 11-19 
    Details
    ISSN: 1573-5060
    Keywords: cluster analysis ; cultivar identification ; electrophoresis ; isozyme ; Rosa spp ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In order to study the polymorphism of the enzyme systems of rose cultivars, experimental conditions were determined to simultaneously extract three systems: esterase (EST), leucine aminopeptidase (LAP) and superoxide dismutase (SOD) which gave up to 9, 7 and 9 bands, respectively. The influence of environmental conditions on the polymorphism level was taken into account. Finally, the computation of the Jaccard distances from the distribution of the isozyme bands led to the improvement of the identification process within an Ancient Rose cultivar collection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003052031309
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  • 90
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    Dissolved oxygen and thermal regimes of a Ugandan crater lake (1998)
    Springer
    Hydrobiologia 385 (1998), S. 201-211 
    Details
    ISSN: 1573-5117
    Keywords: hypoxia ; anoxic hypolimnion ; volcanic crater lake ; stratification ; productivity ; heat budget ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This paper quantifies the temporal pattern of thermal stratification and deoxygenation in Lake Nkuruba, a small (3 ha), deep (maximum depth = 38 m) crater lake in western Uganda. Dissolved oxygen penetrated to an average depth of 9 m and a maximum depth of 15 m below which the lake was permanently anoxic over the 2 years of study. Although surface oxygen levels were correlated with both surface water temperature and rainfall, seasonal cycles of dissolved oxygen were not well-defined and may have been obscured by the high frequency of short-term fluctuations and by inter-annual variations caused by shifts in rainfall. Surface water temperature averaged 23.3±0.7 °C (S.D.) and varied directly with air temperature. Both diurnal changes and top-bottom temperature differentials were small averaging 1.7±0.7 °C and 1.6±0.8 °C, respectively. Thermal stability ranged from 101.3 to 499.9 g-cm cm-2 and was positively related to surface water temperature suggesting that this small protected lake responds rapidly to short-term meteorological changes. Because contribution to the annual heat exchange cycle was confined to upper waters, the lake's annual heat budget was low, 1,073.8 cal cm-2 yr-1. However, net primary productivity was relatively high averaging 1.3 g C m-2d-1. The region where Lake Nkuruba is situated experienced a very strong earthquake (6.2 on the Richter scale) on 4 February, 1994. Subsequently, water levels dropped markedly in the lake, falling 3.14 m over a 5-month period.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003527016384
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  • 91
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    Dissolved oxygen and thermal regimes of a Ugandan crater lake (1998)
    Springer
    Hydrobiologia 385 (1998), S. 201-211 
    Details
    ISSN: 1573-5117
    Keywords: hypoxia ; anoxic hypolimnion ; volcanic crater lake ; stratification ; productivity ; heat budget ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This paper quantifies the temporal pattern of thermal stratification and deoxygenation in Lake Nkuruba, a small (3 ha), deep (maximum depth = 38 m) crater lake in western Uganda. Dissolved oxygen penetrated to an average depth of 9 m and a maximum depth of 15 m below which the lake was permanently anoxic over the 2 years of study. Although surface oxygen levels were correlated with both surface water temperature and rainfall, seasonal cycles of dissolved oxygen were not well-defined and may have been obscured by the high frequency of short-term fluctuations and by inter-annual variations caused by shifts in rainfall. Surface water temperature averaged 23.3±0.7 °C (S.D.) and varied directly with air temperature. Both diurnal changes and top-bottom temperature differentials were small averaging 1.7±0.7 °C and 1.6±0.8 °C, respectively. Thermal stability ranged from 101.3 to 499.9 g-cm cm-2 and was positively related to surface water temperature suggesting that this small protected lake responds rapidly to short-term meteorological changes. Because contribution to the annual heat exchange cycle was confined to upper waters, the lake's annual heat budget was low, 1,073.8 cal cm-2 yr-1. However, net primary productivity was relatively high averaging 1.3 g C m-2d-1. The region where Lake Nkuruba is situated experienced a very strong earthquake (6.2 on the Richter scale) on 4 February, 1994. Subsequently, water levels dropped markedly in the lake, falling 3.14 m over a 5-month period.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003527016384
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    Optimal Control of Nonlinear Fredholm Integral Equations (1998)
    Springer
    Journal of optimization theory and applications 97 (1998), S. 707-729 
    Details
    ISSN: 1573-2878
    Keywords: Nonlinear integral equations ; optimal control in L p-spaces ; relaxation ; existence ; stability ; nonconcentration ; optimality conditions ; Pontryagin maximum principle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract Optimal control problems with nonlinear equations usually do not possess optimal solutions, so that their natural (i.e., continuous) extension (relaxation) must be done. The relaxed problem may also serve to derive first-order necessary optimality condition in the form of the Pontryagin maximum principle. This is done here for nonlinear Fredholm integral equations and problems coercive in an L p-space of controls with p〈+∞. Results about a continuous extension of the Uryson operator play a key role.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022650427993
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    Lagrange's theorem for a class of nonholonomic systems and its application (1998)
    Springer
    Applied mathematics and mechanics 19 (1998), S. 135-146 
    Details
    ISSN: 1573-2754
    Keywords: nonholonomic system ; Lagrange's theorem ; manifold ; stability ; Liapunov's direct method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Mathematics , Physics
    Notes: Abstract The stability problem for the manifold of equilibrium positions of a class of nonholonomic systems is studied in this paper. Based on Liapunov's direct method and the definition of stability. Lagrange's theorem of holonomic systems is extended to a class of nonholonomic conservative systems and dissipative systems, and a new expression is made to the relation between asymptotic stability for the manifold of equilibrium positions of this class of nonholonomic systems and dissipative forces. Two examples are finally given to illustrate the application of the theorems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02457681
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    Biodiversity and environmental stability (1997)
    Springer
    Biodiversity and conservation 6 (1997), S. 315-323 
    Details
    ISSN: 1572-9710
    Keywords: biodiversity ; endemism ; stability ; conservation ; proceedings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Although levels of biological diversity may seem to be equivalent in different areas, diversity is created and maintained by a range of different ]processes: overlap of habitat on gradients; a dynamic mosaic of communities; and accumulation and evolution of taxa in extremely stable areas. These different communities will respond in very different ways to disturbance. The most fragile are those whose component taxa are genetically adapted to the stability of a predictable environment. These areas are often under pressure from local rural populations and require intensive local conservation management actions. In other areas, where diversity is adapted to dynamism, communities are more resilient to disturbance and conservation can be best effected by policy instruments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018304522320
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    Making Beliefs Coherentl. The Subtraction and Addition Strategies. (1998)
    Springer
    Journal of logic, language and information 7 (1998), S. 143-163 
    Details
    ISSN: 1572-9583
    Keywords: Belief revision ; consolidation ; coherence ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Linguistics and Literary Studies , Computer Science
    Notes: Abstract The notion of epistemic coherence is interpreted as involving not only consistency but also stability. The problem how to consolidate a belief system, i.e., revise it so that it becomes coherent, is studied axiomatically as well as in terms of set-theoretical constructions. Representation theorems are given for subtractive consolidation (where coherence is obtained by deleting beliefs) and additive consolidation (where coherence is obtained by adding beliefs).
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    URL: http://dx.doi.org/10.1023/A:1008274704871
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    Stable, recombinant expression of human insulin-like growth factor binding protein-1 (hIGFBP-1) in Chinese hamster ovary (CHO) cells (1997)
    Springer
    Cytotechnology 24 (1997), S. 193-200 
    Details
    ISSN: 1573-0778
    Keywords: CHO cells ; DHFR ; IGFBP-1 ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Stable expression of human insulin-like growth factor of binding protein-1 (hIGFBP-1)at high levels has been achieved in Chinese hamster ovary (CHO) cells by co-transfection and subsequent co-amplification of expression vectors containing the hIGFBP-1 cDNA and a dihydrofolate reductase (DHFR) cDNA gene into DHFR-deficient cells. Stepwise selection of the DHFR+ transformants in increasing concentrations of methotrexate (MTX) generated cells which had high copy numbers of the hIGFBP-1 gene (around 100 copies in cells amplified in medium containing 100 nM MTX). Expression of hIGFBP-1 in mixed clones was found to increase with increasing copy number and an apparent correlation between intra- and extracellular levels of hIGFBP-1 produced by these cells was observed. It was further observed that continuous cultivation over eight months in medium supplemented with 100 nM MTX increased the production of hIGFBP-1 25 times. The productivity did not increase further after five more months cultivation in MTX containing medium. A subcloning of this cell line gave clones with an even higher productivity. Further amplification in 500 nM or 1 uM MTX did not increase the hIGFBP-1 production.
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    URL: http://dx.doi.org/10.1023/A:1007999512662
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    Geographical patterns of old and young species in African forest biota: the significance of specific montane areas as evolutionary centres (1997)
    Springer
    Biodiversity and conservation 6 (1997), S. 325-346 
    Details
    ISSN: 1572-9710
    Keywords: Tropical Africa ; speciation ; stability ; diversity ; forests
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A widely accepted paradigm for speciation in tropical forests, the refuge theory, requires periodic habitat fragmentation driven by global climatic fluctuations to provide conditions for allopatric speciation. This implies that comparative species richness in refugia is due to loss of diverse communities in areas affected by climatic cycles. In this study we compare distribution patterns of bird and plant taxa which we consider to be of either deep phylogenetic lineages or recent radiations. It is demonstrated that lowland areas which have been postulated as Pleistocene refugia are dominated by species which represent lineages of pre-Pleistocene age. Since variations in species richness within these forest tracts reflect currently apparent environmental variables which might be considered to determine carrying capacity, we do not need to postulate that richness is the result of changes in forest cover in the past. Recently diversified taxa of plants and birds are found mainly at the periphery of the main rain forest blocks and in habitat islands outside them. Here, peak concentrations of young restricted-range species are often congruent with clusters of old and biogeographically relictual species. It is suggested that this reflects special intrinsic environmental properties of these areas, in the form of long-term environmental stability caused mainly by persistent orographic rain or mist. In this case, richness is not necessarily due to extinction outside these areas. Stability not only enables survival of relictual taxa, but also promotes morphological differentiation of radiating taxa, leading to aggregates of taxa of restricted distribution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018356506390
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    Effect of Ionic Strength on Solution Stability of PNU-67590A, A Micellar Prodrug of Methylprednisolone (1997)
    Springer
    Pharmaceutical research 14 (1997), S. 1181-1185 
    Details
    ISSN: 1573-904X
    Keywords: stability ; ionic strength ; pH ; critical micelle concentration ; self-micellization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. PNU-67590A is a water-soluble micellar prodrug of methyl-prednisolone (MP). The major products of degradation of PNU-67590A are MP by hydrolysis and methylprednisolone 17-suleptanate (17-E) by 21 → 17 acyl migration. The effect of ionic strength on micelle formation and stability of PNU-67590A in aqueous solution was examined. Methods. PNU-67590A solutions at pH 2 and 8 and ionic strength of 0.05, 0.1, 0.2, and 0.4 M were maintained at 25°C in the dark to measure MP and 17-E levels over time. Results. The rate of degradation of micellar PNU-67590A at pH 8 was less than that of monomeric PNU-67590A, and vice versa at pH 2. Increase in ionic strength decreased both the critical micelle concentration of PNU-67590A and the degradation of micelle PNU-67590A at both pHs, resulting in improved overall stability of PNU-67590A. Conclusions. Formulation of PNU-67590A in a concentrated solution with high ionic strength will maximize stability and shelf-life.
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    URL: http://dx.doi.org/10.1023/A:1012150722729
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    Nasal Absorption Kinetic Behavior of Azetirelin and Its Enhancement by Acylcarnitines in Rats (1998)
    Springer
    Pharmaceutical research 15 (1998), S. 77-81 
    Details
    ISSN: 1573-904X
    Keywords: azetirelin ; thyrotropin-releasing hormone analog ; stability ; nasal absorption ; acylcarnitines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The long-term stability and nasal absorption characteristics of a basic nasal formulation of azetirelin, a thyrotropin-releasing hormone analog and its absorption enhancement by incorporation of acylcarnitines in the formulation were investigated. Methods. The long-term stability of basic nasal azetirelin formulations at 25° C was predicted by calculation from the Arrhenius plot of the data on 6 months' storage at 40, 50 and 60° C. Nasal azetirelin absorption characteristics were kinetically examined by intranasal administration to rats, determination of plasma azetirelin level by radioimmunoassay, and fitting the data to a two-compartment model including absorption rate. Results. Basic nasal azetirelin formulations of pH 4.0 and pH 5.1 were predicted to be highly stable. Residual azetirelin after 2 years storage at 25° C was greater than 95%. Nasal absorption characteristics of this formulation in the pH 4.0−6.3 range showed pH-dependency, with pH 4.0 showing the highest absolute bioavailability (Bioav) of 17.1%. This nasal Bioav was 21 times greater than that of oral administration (0.8%). Acylcarnitines with 12 or more carbon atoms in the acyl chain greatly enhanced nasal absorption of azetirelin: Bioavs with lauroylcarnitine chloride (LCC) and palmitoylcarnitine chloride were 96.9% and 72.9%, respectively. This enhancement by LCC plateaued at the low concentration of 0.1%. Conclusions. The basic nasal azetirelin formulation at pH 4.0 is stable and shows adequate absorption, with nasal absorption having greater Bioav than oral absorption. The 12-carbon acylate LCC was the strongest enhancer among acylcarnitines and provided near-total delivery of the administered dose to the blood.
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    URL: http://dx.doi.org/10.1023/A:1011952804479
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  • 100
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    Interleukin-1 Receptor (IL-1R) Liquid Formulation Development Using Differential Scanning Calorimetry (1998)
    Springer
    Pharmaceutical research 15 (1998), S. 200-208 
    Details
    ISSN: 1573-904X
    Keywords: IL-1R type I ; microcalorimetry ; protein formulation ; stability ; aggregation ; preservatives ; far-uv circular dichroism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To elucidate the solution conditions that confer stability of aqueous IL-1R using differential scanning calorimetry (DSC). Methods. Optimal pH conditions were determined by monitoring degradation products encountered during accelerated studies (at elevated temperatures) using SDS-PAGE. At the pH optimum, DSC screened for excipients that enhanced thermal stability by shifting the Tm to higher values. Using SEC the relationship between thermal unfolding and stability was investigated by considering if lower Tm's in the presence of preservatives correlated with degradation products at 37°C over time. The degree of aggregation relative to that of a control determined the level of stability achieved. Results. Circular dichroism (CD) measurements confirmed molecular modeling studies showing IL-1R to be about 39% β-sheet. Two major transitions characterized the DSC data with Tm's observed near 47°C and 66°C. Among 21 excipients screened, NaCl exhibited the greatest stabilizing influences based on shifting the low temperature transition to 53°C. The low temperature transition was later found to comprise two transitions, yielding a total of three melting transitions for IL-1R. High Tm's arising from the presence of preservatives correlated with the order of stability (i.e., 0.065% phenol 〉 0.1% m-Cresol 〉 0.9% benzyl alcohol). Conclusions. The three melting transitions are consistent in origin with the cooperative unfolding of three unique immunoglobulin-like domains of IL-1R. Optimal stability was achieved in 20 mM sodium citrate at pH 6 with sufficient NaCl to attain the tonicity of human serum. A correlation between the predicted ranking of stability and the extent of aggregation was demonstrated using DSC.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1011902215383
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