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  • stability  (60)
  • Analytical Chemistry and Spectroscopy
  • Chemistry
  • Springer  (60)
  • 1995-1999  (60)
  • 1945-1949
  • 1998  (60)
Collection
Keywords
Publisher
Years
  • 1995-1999  (60)
  • 1945-1949
Year
  • 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
    Electronic Resource
    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
    Electronic Resource
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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
    Electronic Resource
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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
    Electronic Resource
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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 
    Details
    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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  • 8
    Electronic Resource
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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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019175812444
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  • 9
    Electronic Resource
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    On the guaranteed throughput and efficiency of closed re-entrant lines (1998)
    Springer
    Queueing systems 28 (1998), S. 33-54 
    Details
    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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  • 10
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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 
    Details
    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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  • 11
    Electronic Resource
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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 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018977120831
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  • 12
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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 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008250207046
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  • 13
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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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01473582
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  • 14
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    Ethene hydroformylation on Co/SiO2 catalysts (1998)
    Springer
    Catalysis letters 53 (1998), S. 97-101 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019053805618
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  • 15
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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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019080222823
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  • 16
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    Autonomous Intelligent Cruise Control with Actuator Delays (1998)
    Springer
    Journal of intelligent and robotic systems 23 (1998), S. 27-43 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007946007601
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  • 17
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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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1023048322851
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  • 18
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    Robust Regulator for Flexible-Joint Robots Using Integrator Backstepping (1998)
    Springer
    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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    URL: http://dx.doi.org/10.1023/A:1007947416837
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  • 19
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    Resilience in the Dynamics of Economy-Environment Systems (1998)
    Springer
    Environmental and resource economics 11 (1998), S. 503-520 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008255614276
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  • 20
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    Stability of linear time variant dynamic systems with multiple time delays (1998)
    Springer
    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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    URL: http://dx.doi.org/10.1007/BF02487763
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  • 21
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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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    URL: http://dx.doi.org/10.1007/BF02487757
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  • 22
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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 
    Details
    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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    URL: http://dx.doi.org/10.1023/A:1006567306546
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  • 23
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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 
    Details
    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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    URL: http://dx.doi.org/10.1023/A:1006041024109
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    The auto-adjustable damping method for solving nonlinear equations (1998)
    Springer
    Applied mathematics and mechanics 19 (1998), S. 163-168 
    Details
    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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    URL: http://dx.doi.org/10.1007/BF02457684
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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)
    Springer
    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)
    Springer
    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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    Timed Petri Nets in Hybrid Systems: Stability and Supervisory Control (1998)
    Springer
    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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    URL: http://dx.doi.org/10.1023/A:1008293802713
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    Modified Conjugate Gradient Method for the Solution of Ax=b (1998)
    Springer
    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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    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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    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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    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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    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 
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    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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    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 
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    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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    The synthesis of polymer suspension with narrow particle size distribution for immunochemical investigations (1998)
    Springer
    Colloid & polymer science 276 (1998), S. 1068-1077 
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    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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    Money demand stability: Evidence from Spain (1998)
    Springer
    Empirical economics 23 (1998), S. 387-400 
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    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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    Small-Angle Neutron Scattering Studies of Vesicle Stability (1998)
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    International journal of thermophysics 19 (1998), S. 461-470 
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    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 
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    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 
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    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.
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    Breeding for yield and quality in durum wheat (1998)
    Springer
    Euphytica 100 (1998), S. 15-18 
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    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.
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    Stability of performance of tetraploid wheat landraces in the Ethiopian highland (1998)
    Springer
    Euphytica 102 (1998), S. 301-308 
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    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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    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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    Electronic Resource
    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.
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    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.
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    URL: http://dx.doi.org/10.1023/A:1022650427993
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  • 47
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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.
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    URL: http://dx.doi.org/10.1007/BF02457681
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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 
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    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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  • 49
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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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  • 50
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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.
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    URL: http://dx.doi.org/10.1023/A:1011902215383
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    Stability of Nonaqueous Suspension Formulations of Plasma Derived Factor IX and Recombinant Human Alpha Interferon at Elevated Temperatures (1998)
    Springer
    Pharmaceutical research 15 (1998), S. 1090-1095 
    Details
    ISSN: 1573-904X
    Keywords: perfluorodecalin ; nonaqueous suspension ; protein ; alpha interferon ; factor IX ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To identify a suitable nonaqueous, parenterally acceptable suspending vehicle whereby a therapeutic protein is delivered as a stable flowable powder, making it amenable to delivery from sustained delivery systems maintained at body temperature. Methods. Formulations of plasma derived Factor IX (pdFIX) and recombinant human alpha interferon (rhα-lFN) were formulated as dry powders, suspended in various vehicles (perfluorodecalin, perfluorotributylamine, methoxyflurane, polyethylene glycol 400, soybean oil, tetradecane or octanol) and stored at 37°C. Stability was assessed by size exclusion chromatography, reverse phase chromatography, ion exchange chromatography, and bioassay, and was compared to the stability of dry powder formulations stored at 37°C and −80°C. Results. PdFIX was stable when stored at 37°C as a dry powder, or when the dry powder was suspended in the pharmaceutically acceptable vehicles perfluorodecalin or perfluorotributylamine. Suspensions of the powder in other pharmaceutically/parenterally acceptable vehicles such as soybean oil or PEG 400 resulted in aggregation and loss of bioactivity. A dry powder formulation of rhα-lFN suspended in perfluorodecalin was also stable at 37°C. Conclusions. This study shows the potential utility of perfluorinated hydrocarbons as nonaqueous suspending vehicles for long term in-vivo delivery of therapeutic proteins.
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    URL: http://dx.doi.org/10.1023/A:1011994514358
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    PEGylation Prevents the N-Terminal Degradation of Megakaryocyte Growth and Development Factor (1998)
    Springer
    Pharmaceutical research 15 (1998), S. 1822-1827 
    Details
    ISSN: 1573-904X
    Keywords: cytokine ; rHuMGDF ; PEGylation ; diketopiperazine ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. Determine the effect of PEGylation on in-vitro degradation for recombinant human Megakaryocyte Growth and Development Factor (rHuMGDF) in the neutral pH range. Methods. Degradation products were characterized by cation-exchange HPLC, N-terminal sequencing and mass spectrometry. Results. The main route of degradation was through non-enzymatic cyclization of the first two amino acids and subsequent cleavage to form a diketopiperazine and des(Ser, Pro)rHuMGDF. This reaction was prevented by alkylation of the N-terminus by polyethylene glycol (PEG). Conclusions. PEGylation of proteins is commonly performed to achieve increased in-vivo circulation half-lives. For rHuMGDF, an additional advantage of PEGylation was enhancedin-vitro shelf-life stability.
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    URL: http://dx.doi.org/10.1023/A:1011945704248
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    Symbolic Computation of Local Stability and Bifurcation Surfaces for Nonlinear Time-Periodic Systems (1998)
    Springer
    Nonlinear dynamics 17 (1998), S. 1-21 
    Details
    ISSN: 1573-269X
    Keywords: Symbolic computation ; stability ; bifurcation ; nonlinear ; time-periodic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract A new technique is presented for symbolic computation of local stability boundaries and bifurcation surfaces for nonlinear multidimensional time-periodic dynamical systems as an explicit function of the system parameters. This is made possible by the recent development of a symbolic computational algorithm for approximating the parameter-dependent fundamental solution matrix of linear time-periodic systems. By evaluating this matrix at the end of the principal period, the parameter-dependent Floquet Transition Matrix (FTM), or the linear part of the Poincaré map, is obtained. The subsequent use of well-known criteria for the local stability and bifurcation conditions of equilibria and periodic solutions enables one to obtain the equations for the bifurcation surfaces in the parameter space as polynomials of the system parameters. Further, the method may be used in conjunction with a series expansion to obtain perturbation-like expressions for the bifurcation boundaries. Because this method is not based on expansion in terms of a small parameter, it can be successfully applied to periodic systems whose internal excitation is strong. Also, the proposed method appears to be more efficient in terms of cpu time than the truncated point mapping method. Two illustrative example problems, viz., a parametrically excited simple pendulum and a double inverted pendulum subjected to a periodic follower force, are included.
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    URL: http://dx.doi.org/10.1023/A:1008284325276
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    On the Stability of Thermoelastic Materials (1998)
    Springer
    Journal of elasticity 53 (1998), S. 199-213 
    Details
    ISSN: 1573-2681
    Keywords: thermoelasticity ; stability ; strong ellipticity.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A notion of material stability is introduced and discussed in the setting of nonlinear thermoelasticity. Necessary and sufficient conditions are established for the stability of a general thermoelastic material. The adiabatic theory and the theory that accounts for heat conduction are considered separately.
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    URL: http://dx.doi.org/10.1023/A:1007513631783
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    Resonances of a Harmonically Forced Duffing Oscillator with Time Delay State Feedback (1998)
    Springer
    Nonlinear dynamics 15 (1998), S. 311-327 
    Details
    ISSN: 1573-269X
    Keywords: Time delay ; stability ; vibration control ; periodic motion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract The paper presents analytical and numerical studies of the primary resonance and the 1/3 subharmonic resonance of a harmonically forced Duffing oscillator under state feedback control with a time delay. By using the method of multiple scales, the first order approximations of the resonances are derived and the effect of time delay on the resonances is analyzed. The concept of an equivalent damping related to the delay feedback is proposed and the appropriate choice of the feedback gains and the time delay is discussed from the viewpoint of vibration control. In order to numerically solve the problem of history dependence prior to the start of excitation, the concepts of the Poincaré section and fixed points are generalized. Then, a modified shooting scheme associated with the path following technique is proposed to locate the periodic motion of the delayed system. The numerical results show the efficacy of the first order approximations of the resonances.
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    URL: http://dx.doi.org/10.1023/A:1008278526811
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    On the Stability of a Nonlinear Viscoelastic Rod Subjected to a Longitudinal Force in the Form of a Random Stationary Process (1998)
    Springer
    Mechanics of time-dependent materials 2 (1998), S. 335-349 
    Details
    ISSN: 1573-2738
    Keywords: Lyapunov exponents ; numerical methods ; random processes ; reliability ; rods ; stability ; viscoelasticity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The stability and reliability of a nonlinear viscoelastic rod under a stochastic excitation is investigated. The loads are assumed to be in the form of random stationary processes. The solution is obtained with the help of a numerical method, which is based on the method of the statistical simulation of random input processes and on the numerical solution of the system of nonlinear and linearized integro-differential equations. These equations describe a nonperturbed and perturbed motion of the rod. The estimation of the stability is carried out with the help of top Lyapunov exponents.
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    URL: http://dx.doi.org/10.1023/A:1009892927971
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    Parametrically Excited Non-Linear Traveling Beams with and without External Forcing (1998)
    Springer
    Nonlinear dynamics 17 (1998), S. 301-324 
    Details
    ISSN: 1573-269X
    Keywords: parametric excitation ; non-linear complex ; stability ; jump phenomena
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract The effects of parametric excitation on a traveling beam, both with and without an external harmonic excitation, have been studied including the non-linear terms. Non-linear, complex normal modes have been used for the response analysis. Detailed numerical results are presented to show the effects of non-linearity on the stability of the parametrically excited system. In the presence of both parametric and external harmonic excitations, the response characteristics are found to be similar to that of a Duffing oscillator. The results are sensitive to the relative strengths of and the phase difference between the two forms of excitations.
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    URL: http://dx.doi.org/10.1023/A:1008391503175
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    Global Stability Analysis of Cylindrical and Dual Offset Rotor Bearing Systems (1998)
    Springer
    Nonlinear dynamics 16 (1998), S. 187-202 
    Details
    ISSN: 1573-269X
    Keywords: Chaos ; stability ; offset ; bearings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract Extensive numerical simulation studies with a short bearing film model show that a balanced dual offset rotor bearing subjected to a fixed external load can improve bearing performance for load and speed conditions known to produce undesirable half-speed whirl in conventional zero-offset cylindrical systems. For specific values of dimensionless load, offset ratio, and load orientation, parametric changes in speed show that the dual offset bearing can undergo a variety of bifurcations which produce coexisting period 1–4 subharmonic, quasi-periodic, and chaotic attractors, all of which may be driven by lower-order dynamic processes. For a specific set of initial conditions, the transition to chaos via period doubling in the dual offset bearing actually produces lubricant films which are significantly thicker than those found in the corresponding cylindrical system.
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    URL: http://dx.doi.org/10.1023/A:1008256016459
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    Cα-methyl phenylglycine-based semi-synthetic ampicillin and cephalexin analogues (1998)
    Springer
    International journal of peptide research and therapeutics 5 (1998), S. 43-48 
    Details
    ISSN: 1573-3904
    Keywords: antibiotics ; biological activity ; N-carboxy anhydride ; penicillin ; stability ; Cα-tetrasubstituted α-amino acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Reaction of the N-carboxyanhydride from Cα-methyld-phenylglycine with either 6-aminopenicillanic acid or 7-amino-3-desacetoxy-cephalosporanic acid furnishes the corresponding ampicillin and cephalexin analogues. Neither the biological activity nor the chemical stability of these new semi-synthetic antibiotics are superior to those of their unmethylated counterparts.
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    URL: http://dx.doi.org/10.1007/BF02443539
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    Cα-Methyl phenylglycine-based semi-synthetic ampicillin and cephalexin analogues (1998)
    Springer
    International journal of peptide research and therapeutics 5 (1998), S. 43-48 
    Details
    ISSN: 1573-3904
    Keywords: antibiotics ; biological activity ; N-carboxy anhydride ; penicillin ; stability ; Cα-amino acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Reaction of the N-carboxyanhydride from Cα-methyl d-phenylglycine with either 6-aminopenicillanic acid or 7-amino-3-desacetoxy-cephalosporanic acid furnishes the corresponding ampicillin and cephalexin analogues. Neither the biological activity nor the chemical stability of these new semi-synthetic antibiotics are superior to those of their unmethylated counterparts.
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    URL: http://dx.doi.org/10.1023/A:1008806925287
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