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  • Coleoptera  (83)
  • stability  (82)
  • Springer  (165)
  • Institute of Physics
  • 1995-1999
  • 1990-1994  (165)
  • 1940-1944
  • 1993  (98)
  • 1990  (67)
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  • 1995-1999
  • 1990-1994  (165)
  • 1940-1944
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  • 1
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    Computing 51 (1993), S. 271-292 
    ISSN: 1436-5057
    Keywords: 65N15 ; 65N99 ; 35A40 ; Box method ; boundary value problem ; finite volume method ; variational formulation ; stability ; error bounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Box-Methoden (Finite-Volumen-Methoden) sind verbreitete Verfahren zur Lösung physikalischer Erhaltungsgleichungen, insbesondere in der Strömungsmechanik. In dieser Arbeit werden zwei Methoden für elliptische Differentialgleichungen untersucht, die Diagonal-Boxen und die Schwerpunkt-Boxen. Da die Box-Methoden im Sinne von Petrov-Galerkin-Verfahren interpretiert werden können, erhält man vergleichbar zur Finiten-Element-Methode eine variationsrechnerische Stabilitäts- und Fehleranalyse. Damit werdenO(h)- undO(h 2)-Fehlerabschätzungen hergeleitet. Lokale Eigenwertprobleme führen zu Stabilitätsaussagen. Allerdings ergibt sich eine Abhängigkeit von der Anzahl und Art gestörter Vierecke. Insbesondere die Diagonal-Boxen sind anfällig für lokale Störungen.
    Notes: Abstract Box schemes (finite volume methods) are widely used in fluiddynamics, especially for the solution of conservation laws. In this paper two box-schemes for elliptic equations are analysed with respect to quadrilateral meshes. Using a variational formulation, we gain stability theorems for two different box methods, namely the so-called diagonal boxes and the centre boxes. The analysis is based on an elementwise eigenvalue problem. Stability can only be guaranteed under additional assumptions on the geometry of the quadrilaterals. For the diagonal boxes unsuitable elements can lead to global instabilities. The centre boxes are more robust and differ not so much from the finite element approach. In the stable case, convergence results up to second order are proved with well-known techniques.
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  • 2
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    European journal of nutrition 29 (1990), S. 219-228 
    ISSN: 1436-6215
    Keywords: Vitamin K ; Menadion ; Menadiol ; Bioverfügbarkeit ; Stabilität ; Geflügel ; vitamin K ; menadione ; menadiol ; bioavailability ; stability ; poultry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Summary A bioassay of vitamin K is described, based on the prothrombin clotting time of 3-week-old, vitamin-K-depleted, and cumatetralyl-sensitized male broiler chicks, using a homologous thrombokinase preparation. With this test it could be shown that the diacetate and dibutyrate esters of menadiol are vitamin-K-active. The bioactivity of menadione from these menadiolesters amounted to about 70 % of the standard menadione from a coated menadione sodium bisulfite (Dohyfral). Menadiol seems to be temperature-resistant under such conditions, whereby two uncoated MSB preparations lost about 60 % of their activity.
    Notes: Zusammenfassung In einem biologischen Testverfahren an Cumatetralyl sensibilisierten Küken konnte in 3 Versuchen anhand des Parameters Thromboplastinzeit mit homologer Thrombokinase gezeigt werden, da\ Menadioldiacetat und Menadioldibutyrat Vitamin-K-wirksam sind. Die biologische Wirksamkeit von Menadion aus diesen Menadiolestern betrug ca. 70 % der Menadionaktivität aus gecoatetem Menadionbisulfit (Dohyfral®). Im Gegensatz zu 2 ungeschützten MSB-Präparationen, welche bei Wärmebelastung ca. 60 % ihrer ursprünglichen Wirkung verloren, waren die Menadiolester temperaturstabil.
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  • 3
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    Mathematical programming 47 (1990), S. 117-141 
    ISSN: 1436-4646
    Keywords: Bifurcation ; singularity ; parametric programming ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract The structure of solutions to the nonlinear parametric programming problem with a one dimensional parameter is analyzed in terms of the bifurcation behavior of the curves of critical points and the persistence of minima along these curves. Changes in the structure of the solution occur at singularities of a nonlinear system of equations motivated by the Fritz John first-order necessary conditions. It has been shown that these singularities may be completely partitioned into seven distinct classes based upon the violation of one or more of the following: a complementarity condition, a constraint qualification, and the nonsingularity of the Hessian of the Lagrangian on a tangent space. To apply classical bifurcation techniques to these singularities, a further subdivision of each case is necessary. The structure of curves of critical points near singularities of lowest (zero) codimension within each case is analyzed, as well as the persistence of minima along curves emanating from these singularities. Bifurcation behavior is also investigated or discussed for many of the subcases giving rise to a codimension one singularity.
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  • 4
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    Mathematical programming 61 (1993), S. 197-214 
    ISSN: 1436-4646
    Keywords: Epi-convergence ; epi-distance ; stability ; convex optimization ; approximate solutions ; subgradients ; level sets
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract We prove that theε-optimal solutions of convex optimization problems are Lipschitz continuous with respect to data perturbations when these are measured in terms of the epi-distance. A similar property is obtained for the distance between the level sets of extended real valued functions. We also show that these properties imply that theε-subgradient mapping is Lipschitz continuous.
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  • 5
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    Computing 44 (1990), S. 187-196 
    ISSN: 1436-5057
    Keywords: 65M10 ; Spectral method ; stability ; stability threshold
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Zur numerischen Lösung einer nichtlinearen Differentialgleichung dritter Ordnung, herrührend aus einem Strömungsproblem bei Gasteilchen, wird ein zeitdiskreter Pseudo-spektral-Algorithmus vorgeschlagen. Stabilität und Konvergenz des neuen Differenzenverfahrens werden analysiert. Numerische Vergleiche mit bestehenden Differenzenschemata sprechen klar zugunsten des neuen Verfahrens.
    Notes: Abstract A time-discrete pseudospectral algorithm is suggested for the numerical solution of a nonlinear third order equation arising in fluidization. The nonlinear stability and convergence of the new scheme are analyzed. Numerical comparisons with available finite-difference methods are also reported which clearly indicate the superiority of the new scheme.
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  • 6
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    Entomologia experimentalis et applicata 69 (1993), S. 13-20 
    ISSN: 1570-7458
    Keywords: Artificial diets ; Coccinellidae ; rearing ; biological control ; Chilocorus spp. ; Coleoptera
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Promising diets were screened and the most successful modified with additives used in artificial diets for other entomophagous insects. Two suitable diets were obtained, one for adults and one for larvae ofChilocorus nigritus (Fabricius) (Coleoptera: Coccinellidae). They were still inferior to natural prey and not adequate as the sole food source for rearing consecutive generations. They are valuable as substitute food in the insectary during shortages of natural prey. Oleander scaleAspidiotus nerii Bouché andAsterolecanium miliaris (Boisduval) were evaluated as natural prey forC. nigritus and two other potential biocontrol agents in southern Africa,C. bipustulatus (Linnaeus) andC. infernalis Mulsant.A. nerii andA. miliaris were suitable for all life stages ofC. nigritus and adults ofC. bipustulatus andC. infernalis. A. miliaris was inadequate for larvae ofC. bipustulatus andC. infernalis.
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  • 7
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    Entomologia experimentalis et applicata 66 (1993), S. 161-169 
    ISSN: 1570-7458
    Keywords: avoidance behaviour ; capture efficiency ; Coleoptera ; time-lapse video ; visual recording
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Pitfall trap capture forSitophilus oryzae (L.),S. zeamais (Motschulsky),S. granarius (L.),Tribolium confusum (Duval),T. castaneum (Herbst);Oryzaephilus surinamensis (L.),Cryptolestes pusillus (Schonherr),Rhyzopertha dominica (Fabr.), andProstephanus truncatus (Horn) in millet was assessed by visual and time-lapse video recordings. The behaviour of different beetle species in arenas containing millet was monitored over 24 h and the frequency of encounters with the trap rim resulting in capture recorded. The capture efficiency of four types of pitfall traps (i.e. polystyrene, polythene, glass and tin-plated steel can) with rims exposed or submerged below the millet surface level were compared. Capture was related to beetle size, locomotory rate, and beetle behaviour at the trap rim as well as trap design and placement. The lighter and smaller species were least captured. Glass jars were more effective than plastic and metal containers. Traps placed with their rims submerged below the grain surface level were more efficient than those with rims exposed. Capture rate was unrelated to trap size. The frequency of encounters with trap rims was not correlated with capture rate. Three types of avoidance behaviours at the trap rims i.e. probing, skirting and spontaneous retreat, were related to capture rate, spontaneous retreat being the most effective escape mechanism and probing least.
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  • 8
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    Entomologia experimentalis et applicata 66 (1993), S. 191-196 
    ISSN: 1570-7458
    Keywords: Leptinotarsa decemlineata (Say) ; Coleoptera ; Chrysomelidae ; distribution ; diapause ; overwintering ; mortality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 9
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    Journal of intelligent manufacturing 4 (1993), S. 183-198 
    ISSN: 1572-8145
    Keywords: Assembly planning ; subassembly ; liaison graph ; geometric reasoning ; assembly cost ; stability ; partial-order graph
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The distribution of assembly workstations enables assembly operations to be done in parallel, while the multiple routing of parts in flexible assembly systems allows the opportunistic scheduling of assembly operations. This paper presents an assembly planning system, called the Assembly Coplanner, which automatically constructs an assembly partial order and generates a set of assembly instructions from a liaison graph representation of an assembly based on the extraction of preferred subassemblies. Assembly planning in Coplanner is carried out by the co-operation of multiple planning agents, such as the geometric reasoner, the physical reasoner, the resource manager and the plan coordinator, under the constraints of finding a cost-effective assembly plan in a flexible assembly system. The Coplanner identifies spatial parallelism in assembly as a means of constructing temporal parallelism among assembly operations. This is achieved in the following way: (1) the selection of a set of tentative subassemblies by decomposing a liaison graph into a set of subgraphs based on feasibility and difficulty of disassembly; (2) the evaluation of each of the tentative subassemblies in terms of assembly cost represented by subassembly selection indices; and (3) the construction of a hierarchical partial order graph (HPOG) as an assembly plan. A case study applying the Coplanner to a mechanical assembly is illustrated in this paper.
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  • 10
    ISSN: 1572-8900
    Keywords: Chemiluminescence ; oxidation ; stability ; acrylonitrile-butadiene-styrene (ABS) ; ABS/polycarbonate blend
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The thermal oxidative stability of various ABS/PC compounds was studied by means of the chemiluminescence technique. Similarly to pure ABS, Irganox 1076 and Irganox MD 1024 perform as moderate antioxidants in ABS/PC and (ABS/PC + lubricant) blends. Neither Tinuvin 144, Irgaphos 168, nor their mixture affects the durability of the ABS/PC blend. At the same time, (Irgaphos 168 + Tinuvin 144) in combination with Irganoxes was found to provide a noticeable enhancement in durability to the (ABS/PC + lubricant) system. Titanium dioxide pigments by themselves have only a slight influence on the oxidative stability of the ABS/PC blend. Durability of the (ABS/PC + pigment) and (ABS/PC + lubricant) systems was found to be the same and the overall protective effect of Irganox 1076 was similar in both the (ABS/PC + lubricant) and the (ABS/PC + lubricant + pigment) systems. Certain modifiers significantly improve the durability of the ABS/PC compounds, although their function may differ in the systems with and without pigments.
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  • 11
    ISSN: 1572-8900
    Keywords: Chemiluminescence ; oxidation ; stability ; acrylonitrile-butadiene-styrene (ABS)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The influence of lubricants, UV stabilizers, antioxidants, and metal deactivators on the resistance of ABS to thermal oxidation was studied by means of the chemiluminescence technique. Neither of the additives seems to affect significantly the induction period of oxidation. At the same time, the influence of various additives on the oxidation rate constant is remarkably different: the introduction of lubricants and UV stabilizers increases its value, while antioxidants and metal deactivators have the opposite effect. For the particular systems studied durability is decreased in samples containing the lubricant and UV stabilizers and increased in samples stabilized with the antioxidant and metal deactivator.
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  • 12
    ISSN: 1572-8889
    Keywords: Coleoptera ; Scarabaeidae ; Cotinis nitida (L.) ; beetle flight ; pheromone bioassay
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 13
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    Queueing systems 13 (1993), S. 87-110 
    ISSN: 1572-9443
    Keywords: Manufacturing systems ; semiconductor manufacturing ; thin film lines ; re-entrant lines ; scheduling policies ; queueing networks ; buffer priority policies ; due date policies ; stability ; stochastic control ; mean delay ; variance of delay ; machine failures ; set-up times
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract Traditionally, manufacturing systems have mainly been treated as either job shops or flow shops. In job shops, parts may arrive with random routes, with each route having a low volume. In flow shops, the routes are fixed and acyclic, as in assembly lines. With the advent of semiconductor manufacturing plants, and more recently, thin film lines, this dichotomy needs to be expanded to consider another class of systems, which we call “re-entrant lines”. The distinguishing feature of these manufacturing systems is that parts visit some machines more than once at different stages of processing. Scheduling problems arise because several parts at different stages of processing may be in contention with each other for service at the same machine. There may be uncertainties in the form of random service or set-up times, as well as random machine failures and repairs. The goal of scheduling is to improve performance measures such as mean sojourn time in the system, which is also known as the mean “cycle-time”, or the variance of the cycle-time. In this paper we provide a tutorial account of some recent results in this field. We describe several scheduling policies of interest, and provide some results concerning their stability and performance. Several open problems are suggested.
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  • 14
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    Celestial mechanics and dynamical astronomy 56 (1993), S. 45-50 
    ISSN: 1572-9478
    Keywords: Restricted problem ; stability ; planets of double stars
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Numerical simulations are made within the framework of the plane restricted three-body problem, in order to find out if stable orbits for planets around one of the two components in double stars can exist. For any given set of initial parameters (the mass ratio of the two stars and the eccentricity of their orbit around each other), the phase-space of initial positions and velocities is systematically explored. In previous works, systematic exploration of the circular model as well as studies of more realistic (elliptic) cases such as Sun-Jupiter and the nearby α Centauri and Sirius systems, large stable planetary orbits were found to exist around both components of the binary, up to distances from each star of the order or more than half the binary's periastron separation. The first results presented here for the η Coronae Borealis system confirm the previous studies.
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  • 15
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    Journal of dynamics and differential equations 5 (1993), S. 625-671 
    ISSN: 1572-9222
    Keywords: Scalar reaction-diffusion equation ; singular perturbation methods ; internal layer ; Neumann layer ; stability ; 35K57 ; 35B25 ; 35B35
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract The multiple existences and their stability properties of stationary solutions with a single transition layer in some scalar reaction-diffusion equation are shown. Each solution is constructed by using classical singular perturbation methods and its stability property is determined by a simple algebraic quantity, say index, appearing in the construction of a solution.
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  • 16
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    Annals of operations research 27 (1990), S. 343-369 
    ISSN: 1572-9338
    Keywords: Bifurcation ; singularities ; continuation ; parametric nonlinear programming ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Notes: Abstract Bifurcation and continuation techniques are introduced as a class of methods for investigating the parametric nonlinear programming problem. Motivated by the Fritz John first-order necessary conditions, the parametric programming problem is first reformulated as a closed system of nonlinear equations which contains all Karush-Kuhn-Tucker and Fritz John points, both feasible and infeasible solutions, and relative minima, maxima, and saddle points. Since changes in the structure of the solution set and critical point type can occur only at singularities, necessary and sufficient conditions for the existence of a singularity are developed in terms of the loss of a complementarity condition, the linear dependence constraint qualification, and the singularity of the Hessian of the Lagrangian on a tangent space. After a brief introduction to elementary bifurcation theory, some simple singularities in this parametric problem are analyzed for both branching and persistence of local minima. Finally, a brief introduction to numerical continuation and bifurcation procedures is given to indicate how these facts can be used in a numerical investigation of the problem.
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    Queueing systems 14 (1993), S. 159-175 
    ISSN: 1572-9443
    Keywords: Queueing networks ; nonproduct form networks ; stability ; stochastic continuity ; functional limit theorems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract A finite number of nodes, each with a single server and infinite buffers, is considered in discrete time. The service may be FIFO and the service times are constant. The external arrivals and the routing decision variables form a general stationary sequence. Stability of the system is proved under these assumptions. Extension to multiple servers at a node and general stationary distributions holds. If the external input is i.i.d. and the routing is Markovian then stochastic ordering, continuity of stationary distributions, rates of convergence, a functional CLT and a functional LIL and various other limit theorems for the queue length process are also proved. Generalizations to multiple servers at nodes, customers with priority, multiple customer classes, general service length and Markov modulated external arrival cases are discussed.
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    Journal of dynamics and differential equations 5 (1993), S. 189-218 
    ISSN: 1572-9222
    Keywords: Equivariant bifurcation ; symmetry ; singularity ; equivariant jets and transversality ; normal forms ; universal unfolding ; stability ; structural stability ; 58F14 ; 58E07 ; 58C27
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract The theoretical machinery from singularity theory introduced by Golubitsky, Stewart, and Schaeffer, to study equivariant bifurcation problems, is completed and expanded while generalized to the multiple parameter context. In this setting the finite determinacy theorems or normal forms, the stability of equivariant bifurcation problems, and the structural stability of the universal unfolding are discussed.
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  • 19
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    Set-valued analysis 1 (1993), S. 393-402 
    ISSN: 1572-932X
    Keywords: Primary: 49J40, 65K10, 47A55, 47H05, 65L20 ; Variational inequality ; perturbation ; unbounded and nonsmooth operators ; convex sets ; Hausdorff distance ; regularization ; monotonicity ; convergence ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract The stability and convergence of the solutions of perturbed and regularized variational inequality to the solutions of the primary (unstable a priori) variational inequality with proper monotone operator are investigated. All the objects of inequality: the operatorA, the right-hand partf and the set of constrains Ω are to be perturbed. At the same time no assumptions of boundedness and smoothness of the operatorA are used. The connection between the parameters of perturbations, which guarantees strong convergence of approximate solutions, is established. It is proved that the existence of the solution to the unperturbed variational inequality is necessary and sufficient condition for convergence of the regularized perturbed inequality solutions.
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    Queueing systems 6 (1990), S. 335-351 
    ISSN: 1572-9443
    Keywords: State-dependent service and interarrival times ; Lindley equation ; recursive stochastic equations ; stability ; stochastic comparisons ; normal approximations ; scheduling arrivals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract We consider a modification of the standardG/G/1 queue with unlimited waiting space and the first-in first-out discipline in which the service times and interarrival times depend linearly and randomly on the waiting times. In this model the waiting times satisfy a modified version of the classical Lindley recursion. We determine when the waiting-time distributions converge to a proper limit and we develop approximations for this steady-state limit, primarily by applying previous results of Vervaat [21] and Brandt [4] for the unrestricted recursionY n+1=C n Y n +X n . Particularly appealing for applications is a normal approximation for the stationary waiting time distribution in the case when the queue only rarely becomes empty. We also consider the problem of scheduling successive interarrival times at arrival epochs, with the objective of achieving nearly maximal throughput with nearly bounded waiting times, while making the interarrival time sequence relatively smooth. We identify policies depending linearly and deterministically upon the work in the system which meet these objectives reasonably well; with these policies the waiting times are approximately contained in a specified interval a specified fraction of time.
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    Journal of dynamics and differential equations 5 (1993), S. 105-128 
    ISSN: 1572-9222
    Keywords: Delay system ; stability ; relative variance ; dynamical disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract A new approach to the study of delay systems, applicable to physiological control systems and other systems where little information about the time delays is available, is examined. The method is based on the fact that stability information can be deduced from the statistical properties of the probability distribution that encodes the structure of the time delay. The main statistical variables used are the usual expectation parameter,E, and a modified variance, calledrelative variance and denotedR, that is invariant under time scale changes. Recent work of the author has shown that stability often improves asR increases whileE remains fixed. A four-parameter family of delay models is analysed in this paper, and the (E, R) pair is found to be a reliable indicator of stability over the global parameter domain of the family.
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    Journal of solution chemistry 22 (1993), S. 1151-1158 
    ISSN: 1572-8927
    Keywords: Molecular complexes ; solvent effect ; stability ; solid CT complexes ; nicotine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Interaction of nicotine with tetracyanoethylene and iodine was investigated spectrophotometrically and found to form strong CT complexes (n−π and n-σ*, respectively). The donor site involved in CT interaction is the pyrrolidine nitrogen. The nicotine-I2 complex exists as the ionic structure (nicotine) I+-I 3 − . Formation constants of the CT complexes in various solvents were determined from 10 to 25°C and are discussed in terms of the nature of the electron acceptor and solvent polarity. Solid CT complexes were synthesized and were characterized by microchemical analysis and infrared spectra techniques.
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    Annals of global analysis and geometry 11 (1993), S. 387-395 
    ISSN: 1572-9060
    Keywords: Curvatures of hypersurfaces ; Reilly's inequality ; stability ; 53 A 10 ; 53 C 42
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract We generalize Reilly's inequality for the first eigenvalue of immersed submanifolds ofIR m +1 and the total (squared) mean curvature, to hypersurfaces ofIR m +1 and the first eigenvalue of the higher order curvatures. We apply this to stability problems. We also consider hypersurfaces in hyperbolic space.
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    BIT 33 (1993), S. 332-350 
    ISSN: 1572-9125
    Keywords: AMS(MOS): 65L06 ; Multistep collocation method ; continuous solution ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract This paper describes an implementation of multistep collocation methods, which are applicable to stiff differential problems, singular perturbation problems, and D.A.E.s of index 1 and 2. These methods generalize one-step implicit Runge-Kutta methods as well as multistep one-stage BDF methods. We give numerical comparisons of our code with two representative codes for these methods, RADAU5 and LSODE.
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    Entomologia experimentalis et applicata 54 (1990), S. 219-224 
    ISSN: 1570-7458
    Keywords: Diabrotica virgifera virgifera ; Coleoptera ; Chrysomelidae ; corn ; life-stage occurrence ; planting date
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Dans les conditions de l'est du Sud Dakota (USA), 3 dates de semailles de maïs et 3 dates de contamination avec des œufs de D. virgifera virgifera LeConte ont servi à imposer ou à empêcher la synchronisation des éclosions des œufs et par conséquent des développements ultérieurs. Les dates médianes d'apparition de chacun des 3 stades larvaires et des imagos ont été déterminées en relation avec les unités de température et le nombre de jours depuis la contamination. Aucune différence significative entre les dates médianes d'apparition n'a été mise en évidence par utilisation des unités de température; par contre, ces différences deviennent significatives lorsque l'on utilise le nombre de jours depuis la contamination. Des paramètres fiables sont nécessaires pour prédire la présence des différentes stades de cet insecte. En dépit des différentes conditions imposées pour cette étude, la méthode la moins capricieuse pour prédire l'apparition d'un stade larvaire et l'émergence des adultes est la somme de températures avec une base de 11°C.
    Notes: Abstract Under field conditions in eastern South Dakota, USA three different planting dates of corn and three times of egg infestation were used to imposed synchronous and asynchronous timing of corn growth and Diabrotica virgifera virgifera LeConte egg hatch and subsequent development. Median occurrence of each of the three larval stages and of the adult stage for each of the infestation-planting treatments was determined by relating occurrence to thermal units and to days after infestation. No significant differences were found among the treatments for median occurrence of each life stage when the thermal unit approach was used. However, significant differences were found among treatments for median occurrence when the day after infestation approach was used. Consistent parameters are needed for prediction of the occurrence of life stages of this insect. Despite the various imposed conditions, this study indicates that the least variable method of predicting life stage occurrence and adult emergence of D. v. virgifera was the use of thermal unit accumulations (base 11°C).
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    Entomologia experimentalis et applicata 68 (1993), S. 9-13 
    ISSN: 1570-7458
    Keywords: bioassay ; behavioural response ; Coleoptera ; carob extract ; stored product
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    Topics: Biology
    Notes: Abstract The behavioural responses ofCryptolestes pusillus Oryzaephilus surinamensis andProstephanus truncatus to different doses of carob extract were assessed in a two-choice pitfall bioassay and in plastic grain probe traps. The extract evoked a quick directional response and induced high beetle attraction to treated pitfall arenas compared with the controls. Overall, the extract improved probe trap efficiency by about 50% compared to unbaited probes. Beetle response was dose-dependent with the medium dose of 10 μl probably eliciting optimum response.
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    Annals of global analysis and geometry 11 (1993), S. 221-235 
    ISSN: 1572-9060
    Keywords: Second variation formula ; Morse index ; stability ; 53C
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    Topics: Mathematics
    Notes: Abstract Iff is a minimal, isometric immersion of the Riemannian manifoldM of dimensionn in a Riemannian manifold $$\overline M$$ of dimensionm and ifI N is the „differential Jacobi operator” acting on the cross sections of the normal bundleN(M), we obtain some information on the Morse index and on the stability ofM through a detailed geometric analysis of the immersionf obtained when considering the higher fundamental forms off.
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    BIT 30 (1990), S. 332-346 
    ISSN: 1572-9125
    Keywords: 65D05 ; polynomial interpolaton ; Newton form ; stability ; Leja points ; ordering of interpolation points
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    Topics: Mathematics
    Notes: Abstract The Newton form is a convenient representation for interpolation polynomials. Its sensitivity to perturbations depends on the distribution and ordering of the interpolation points. The present paper bounds the growth of the condition number of the Newton form when the interpolation points are Leja points for fairly general compact sets K in the complex plane. Because the Leja points are defined recursively, they are attractive to use with the Newton form. If K is an interval, then the Leja points are distributed roughly like Chebyshev points. Our investigation of the Newton form defined by interpolation at Leja points suggests an ordering scheme for arbitrary interpolation points.
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    Celestial mechanics and dynamical astronomy 49 (1990), S. 219-231 
    ISSN: 1572-9478
    Keywords: n-body problem ; stability ; relative equilibrium
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    Topics: Physics
    Description / Table of Contents: Abstract We prove in this paper the instability, for all n ⩾ 4, of the configurations of relative equilibrium in the n-body problem where the n bodies submitted to newtonian mutual attractions are at the vertices of a regular polypon with n sides. For this proof we show that the equations of variations projected to the n bodies plan P have at least two conjugate characteristic exponents with a strictly positive real part; while these equations projected to an orthogonal axis to P have some solutions with secular terms.
    Notes: Resumé On démontre dans cet article l'instabilité, pour tout n ⩾ 4, des configurations d'équilibre relatif dans le problème des n corps, oú les n corps soumises aux attractions newtonniennes mutuelles se trouvent aux sommets d'un polygone régulier de n cotés. La preuve consiste à montrer que les équations aux variations, projetées sur le plan P des n corps, possèdent au moins deux exposants caractéristiques complexes connugués dont la parr'e réelle est strictement positive; alors que ces equations projetées sur un axe orthogonal à P possèdent des solutions ayant des termes séculaires.
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    Celestial mechanics and dynamical astronomy 56 (1993), S. 323-324 
    ISSN: 1572-9478
    Keywords: chaos ; stability ; asteroids
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    Celestial mechanics and dynamical astronomy 57 (1993), S. 59-94 
    ISSN: 1572-9478
    Keywords: asteroids ; libration ; proper elements ; stability ; chaos ; families
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    Topics: Physics
    Notes: Abstract I have computed proper elements for 174 asteroids in the 1 : 1 resonance with Jupiter, that is for all the reliable orbits available (numbered and multi-opposition). The procedure requires numerical integration, under the perturbations by the four major planets, for 1,000,000 years; the output is digitally filtered and compressed into a “synthetic theory” (as defined within theLONGSTOP project). The proper modes of oscillation of the variables related to eccentricity, perihelion, inclination and node define proper elements. A third proper element is defined as the amplitude of the oscillation of the semimajor axis associated with the libration period; because of the strong nonlinearity of the problem, this component cannot be determined by a simple Fourier transform to the frequency domain. I therefore give another definition, which results in very good stability with time. For 87% of the computed orbits, the stability of the proper elements-at least over 1M yr-is within the following bounds: 0.001AU in semimajor axis, 0.0025 in eccentricity and sine of inclination. Half of the cases with degraded stability of the proper elements are found to be chaotic, with e-folding times between 16,000 and 660,000yr; in some other cases, chaotic behaviour does not result in a significantly decreased stability of the proper elements (stable chaos). The accuracy and stability of these proper elements is good enough to allow a search for asteroid families; however, the dynamical structure of the Trojan belt is very different from the one of the main belt, and collisional events among Trojans can result in a distribution of fragments difficult to identify. The occurrence of couples of Trojans with very close proper elements is proven not to be statistically significant in almost all cases. As the only exception, the couple 1583 Antilochus — 3801 Thrasimedes is significant; however, it is not easy to account for it by a conventional collisional theory. The Menelaus group is confirmed as a strong candidate collisional family; Teucer and Sarpedon could be considered as significant clusters. A number of other clumps are detected (by the same automated clustering method used for the main belt by Zappalà et al., 1990, 1992), but the total number of Trojans with reliable orbits is not large enough to detect many significant candidate families.
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    Celestial mechanics and dynamical astronomy 49 (1990), S. 249-264 
    ISSN: 1572-9478
    Keywords: Solar sails ; radiation pressure ; stability
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    Topics: Physics
    Notes: Abstract The form of the solar radiation pressure on a heliocentric orbiting solar sail is obtained for a finite angular sized and limb darkened solar disk by the use of the radiation pressure tensor. It is found that the usual inverse square variation of the solar radiation pressure is modified by the finite angular size, and to a lesser extent by the solar limb darkening. The actual magnitude of the modification is in itself small, except at close heliocentric distances. However, its existence has implications for the dynamical stability of solar sails both in parked and circular orbital configurations and for the accuracy of trajectory calculations, particularly for sails in the inner solar system.
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    Celestial mechanics and dynamical astronomy 55 (1993), S. 249-259 
    ISSN: 1572-9478
    Keywords: Asteroid ; libration ; resonance ; stability
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    Topics: Physics
    Notes: Abstract This paper investigates the stability of the motion in the averaged planar general three-body problem in the case of first-order resonance. The equations of the averaged motion of bodies near the resonance surface is obtained and is analytically integrated by quadratures. The stability of the averaged motion is analytically investigated in relation to the semi-major axes, the eccentricities and the resonance phases. An autonomous second-order equation is obtained for the deviation of semiaxes from the resonance surface. This equation has an energy integral and is analytically integrated by quadratures. The quasi-periodic dependence on time with two-frequency basis of the averaged motion of bodies is found. The basic frequencies are analytically calculated. With the help of the mean functionals calculated along integral curves of the averaged problem the new analytic first integrals are constructed with coefficients periodic in time. The analytic conditions of librations of resonance phases are obtained.
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    Celestial mechanics and dynamical astronomy 55 (1993), S. 323-330 
    ISSN: 1572-9478
    Keywords: Periodic orbits ; rigid body dynamics ; stability
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    Topics: Physics
    Notes: Abstract The equations of motion of a rigid body about a fixed point in a central Newtonian field is reduced to the equation of plane motion under the action of potential and gyroscopic forces, using the isothermal coordinates on the inertia ellipsoid. The construction of periodic solutions near the equilibrium points, by using the Lipaunov theorem of holomorphic integral, is obtained and the necessary and sufficient conditions for the stability of the system are given.
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    Celestial mechanics and dynamical astronomy 55 (1993), S. 351-367 
    ISSN: 1572-9478
    Keywords: Sitnikov's problem ; invariant rotational curves ; stability
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    Topics: Physics
    Notes: Abstract The Sitnikov's Problem is a Restricted Three-Body Problem of Celestial Mechanics depending on a parameter, the eccentricity,e. The Hamiltonian,H(z, v, t, e), does not depend ont ife=0 and we have an integrable system; ife is small the KAM Theory proves the existence of invariant rotational curves, IRC. For larger eccentricities, we show that there exist two complementary sequences of intervals of values ofe that accumulate to the maximum admissible value of the eccentricity, 1, and such that, for one of the sequences IRC around a fixed point persist. Moreover, they shrink to the planez=0 ase tends to 1.
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    BIT 33 (1993), S. 74-84 
    ISSN: 1572-9125
    Keywords: 65J10 ; 65M12 ; Analytic semigroup ; Banach space ; rational approximation ; A-acceptable ; A(θ)-acceptable ; stability ; Crank-Nicolson method
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    Topics: Mathematics
    Notes: Abstract It is shown thatA-acceptable and, more generally,A(θ)-arational approximations of bounded analytic semigroups in Banach space are stable. The result applies, in particular, to the Crank-Nicolson method.
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    BIT 33 (1993), S. 285-303 
    ISSN: 1572-9125
    Keywords: 65L05 ; stiffness ; stability ; pseudospectra
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    Topics: Mathematics
    Notes: Abstract It is argued that even for a linear system of ODEs with constant coefficients, stiffness cannot properly be characterized in terms of the eigenvalues of the Jacobian, because stiffness is a transient phenomenon whereas the significance of eigenvalues is asymptotic. Recent theory from the numerical solution of PDEs is adapted to show that a more appropriate characterization can be based upon pseudospectra instead of spectra. Numerical experiments with an adaptive ODE solver illustrate these findings.
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    Aquatic sciences 52 (1990), S. 330-344 
    ISSN: 1420-9055
    Keywords: Flood ; phytoplankton succession ; reversion ; stability
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    Topics: Biology
    Notes: Abstract The effect of the August 1987 River Reuss flood event on the phytoplankton biocoenosis in Lake Uri (Urnersee, part of Lake Lucerne, Switzerland) was investigated firstly by comparing biological, chemical and physical data sampled before the event with equivalent data sampled after the event; and secondly by comparing the phytoplankton succession in 1987 with that occurring in the “floodfree” year 1989. As a consequence of the flood, the physical and chemical environment of the phytoplankton was found to have undergone a change which resulted in an alteration in the composition of the phytoplankton community. The phytoplankton community existing previous to the flood event, which had been dominated byTabellaria fenestrata sensu Husted 1930 (K-strategist), was replaced by a biocoenosis characterized mainly by various species of flagellates, which represent a typical spring successional stage (r-strategists). After the externally-imposed perturbation, the return to stable physical and chemical conditions was followed by the re-establishment of the successional stage which had existed before the flood (termed “reversion” by Reynolds, 1980).
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    Cellular and molecular life sciences 46 (1990), S. 700-704 
    ISSN: 1420-9071
    Keywords: Coleoptera ; Tenebrionidae ; Tribolium confusum ; defesive secretion ; biosynthesis of 1-alkenes ; oxidative decarboxylation ; anti-elimination
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    Topics: Biology , Medicine
    Notes: Summary The terminally unsaturated hydrocarbons of the defensive secretion ofTribolium confusum are biosynthesized from fatty acids by oxidative decarboxylation. The process involves an enantiospecific cleavage of the C−H bond of thepro-(S) C(3)−H atom and simultaneous decarboxylation of the acid into an 1-alkene and carbon dioxide via ananti-periplanar transition state geometry (anti-elimination). The stereochemistry of this biotranformation is identical in all respects with the same reaction in higher plants. The mechanism seems to be of general importance for the biosynthesis of many vinylic substructures of natural products from oxygen-containing precursors.
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    Cellular and molecular life sciences 49 (1993), S. 171-174 
    ISSN: 1420-9071
    Keywords: Coleoptera ; Meloidae ; Epicauta funebris ; chemical defense ; biosynthesis ; terpenoid
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    Topics: Biology , Medicine
    Notes: Abstract Cantharidin, a potent defensive chemical, is present in all ten life stages of the blister beetleEpicauta funebris. The first five larval stages accumulate cantharidin as they feed and grow in size. When disturbed, they exude cantharidin in a milky oral fluid, not in hemolymph which adult beetles reflexively discharge from leg joints. Two subsequent larval stages and the pupa do not feed, grow, regurgitate, or change in their defensive reserves (110 μg cantharidin/insect, regardless of sex). Adult beetles kept in isolation for 60–90 d exhibit a pronounced sexual dimorphism in cantharidin production: the male biosynthesizes about 17 mg of the toxin, representing 10% of his live weight, whereas the female actually loses most of her defensive reserves. But in the wild a female beetle repeatedly acquires cantharidin as copulatory gifts from her mates.
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    Cellular and molecular life sciences 49 (1993), S. 272-275 
    ISSN: 1420-9071
    Keywords: Semiochemical ; pheromone ; host selection ; competition ; Coleoptera ; Scolytidae
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    Topics: Biology , Medicine
    Notes: Abstract Bark beetles,Ips typographus andPityogenes chalcographus, attracted by synthetic or natural pheromone to Norway spruce logs,Picea abies, preferred to colonize uninfested logs rather than logs occupied by these beetles, probably as a means of avoiding intra-and interspecific competition. The aggregation pheromone components ofP. chalcographus, chalcogran and methyl (E, Z)-2,4-decadienoate, inhibited the attraction response ofI. typographus to its pheromone components (methyl butenol andcis-verbenol), while the converse was not true. However, verbenone released from colonized bark inhibited pheromonal response ofP. chalcographus.
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    Entomologia experimentalis et applicata 56 (1990), S. 15-21 
    ISSN: 1570-7458
    Keywords: Coleoptera ; Chrysomelidae ; corn rootworms ; age-specific survival ; age-specific fecundity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé D. virgifera virgifera LeConte a été placé sur des régimes nutritifs mimant l'évolution des tissus du maïs disponsibles dans le champ lorsque les insectes éclosent est aux stades suivants du maïs: 1) après émergence de l'épi mâle, mais avant l'apparition des barbes et l'émission du pollen; 2) lors de la présence de barbes et de l'émission de pollen; 3) après la pollinisation et quand les barbes ont bruni. Un quatrième régime a été fourni pendant toute l'expérience comprenant des barbes vertes, du pollen et des feuilles. Les pontes moyennes des femelles pendant les 12 semaines de l'étude on été 125, 235, 179 et 441 pour les régimes 1, 2, 3 et 4. Les dates de mort de la moitié des adultes a été 7,2, 7,2, 6,7 et 8,8 semaines pour respectivement les mêmes régimes. Les femelles du régime 1 pondent à un âge plus avancé que les femelles des régimes 2 et 3. L'influence des changements de la qualité alimentaire du maïs au fur et à mesure du vieillissement des plantes et deDiabrotica, a été déterminée par la survie au bout de 48 heures d'insectes éclos depuis peu et d'autres maintenus en cage sur des lots de maïs à différents stades poussant en serre depuis des temps plus ou moins longs. Plus les plantes sont âgées, plus la survie des 2 groupes deDiabrotica diminue, mais plus vite chez les lots d'insectes âgés.
    Notes: Abstract Adult corn rootworm beetles,Diabrotica virgifera virgifera LeConte, were maintained on three dietary regimes which mimicked the progression of corn tissues that would be available in the field for beetles eclosing when corn was in the following growth stages: (A) after tassels had emerged but prior to silking and pollen shed; (B) while plants were silking and shedding pollen; and (C) after pollination was complete and silks had turned brown. A fourth regime (D) was established in which green corn silks, pollen, and leaves were provided throughout the study. The mean number of eggs laid per female over the 12-week duration of the study was 125, 235, 179, and 441 for regimes A, B, C, and D, respectively. Median length of life was 7.2, 7.2, 6.7, and 8.8 weeks for regimes A, B, C, and D respectively. Beetles in regime A laid a greater proportion of their eggs at an older age than did beetles from regimes B and C. To further investigate the influences on survival of changes in food quality of corn as plants and beetles aged, newly-eclosed beetles and beetles that had been maintained in caged plots of corn growing in a greenhouse for various lengths of time were caged on corn at different stages of growth, and the proportion of beetles surviving for 48 h was determined. Survival decreased as plants aged for both groups of beetles, but decreased at a faster rate for old than for young beetles.
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    Journal of intelligent and robotic systems 3 (1990), S. 259-289 
    ISSN: 1573-0409
    Keywords: Nonlinear decoupling ; feedback linearization ; functional analysis ; elastic robots ; robustness ; stability ; pole assignment ; nonlinear systems ; robot control
    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 robustness analysis and synthesis for incomplete nonlinear decoupling for a class of nonlinear systems is discussed. Rigid and elastic-joint robot models belong to this class. For the elastic case, a transformation facilitates the robustness analysis under a weak assumption. Charts with H 1- and H ∞- norms of closed-loop disturbance transfer functions of the nonlinear-decoupled system are presented for a robust pole assignment.
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    K-Theory 7 (1993), S. 333-367 
    ISSN: 1573-0514
    Keywords: Locally flat embedding ; pointed Hermitian module ; splitting ; stability
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    Topics: Mathematics
    Notes: Abstract We prove an existence result for topologically locally flat embeddings of 2-spheres in simply connected 4-manifolds. This topological result is deduced from a splitting theorem for pointed Hermitian modules over a cyclic group ring. A stability result for such modules is also proved. This applies to the isotopy classification of locally flat embeddings.
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    Multidimensional systems and signal processing 4 (1993), S. 91-101 
    ISSN: 1573-0824
    Keywords: Bilinear transformation ; polynomial ; stability
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    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The paper presents a unified approach to calculation, for a given, nominal,G-stable polynomial, a corresponding stability region in the space of perturbed coefficients
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    Multidimensional systems and signal processing 4 (1993), S. 331-354 
    ISSN: 1573-0824
    Keywords: two-dimensional discrete-time systems ; two-dimensional digital filters ; bivariate polynomials ; stability ; Bistritz tabular form ; Jury tabular form ; Schur-Cohn minors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract In determining root distribution of univariate polynomials with real or complex-valued coefficients, the Bistritz tabular form offers a significant computational advantage. Stability studies of two-dimensional (2-D) discrete-time systems involve univariate polynomials possessing parameter-dependent coefficients, where the parameter takes values on the unit circle in the complex plane. This paper investigates the application of Bistritz tabular form in determining stability of 2-D discrete-time systems, and for this purpose we present two algorithms. Both algorithms utilize a recent result that has established the relationship between Schur-Cohn minors and the entries of the Bistritz tabular form corresponding to a given polynomial. A comparison between the use of the modified Jury table and the Bistritz table in stability checking of 2-D discrete-time systems is also presented.
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    Journal of superconductivity 6 (1993), S. 55-57 
    ISSN: 1572-9605
    Keywords: Superconductivity ; Bi-2223 ; stability
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    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract A general acid-base equilibrium theory was proposed to explain the formation and stability of the Bi-2223 phase based on the Lewis acid-base theory, and principle of metallurgical physical chemistry. The acid-base nature of oxide was defined according to the electrostatic force between cation and oxygen anion. A series of experimental facts were systematically explained based on the theory: substitution of Bi for Ca in. the Pb-free 2223 phase, and the effect of substitution of the high-valent cation for Bi3+; oxygen-pressure atmosphere, and the heat-schocking technique on the formation and stability of the 2223 phase.
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  • 48
    ISSN: 1423-0445
    Keywords: toxin sequestration ; predation ; human dietary hazard ; cantharidin ; Coleoptera ; Meloidae ; Epicauta vittata ; Rana ; Hirudo ; Nerodia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Frogs(Rana pipiens) fed on blister beetles (Meloidae) or cantharidin, retain cantharidin systemically. After cessation of feeding, they void the compound relatively quickly. Systemic cantharidin does not protect frogs against ectoparasitic feeding by leeches(Hirudo medicinalis) or predation by snakes(Nerodia sipedon). As suggested by our data, and from reports in the early literature, ingestion of cantharidin-containing frogs can pose a health threat to humans.
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  • 49
    ISSN: 1423-0445
    Keywords: pheromone ; attractant ; triene ; tetraene ; hydrocarbon ; Insecta ; Coleoptera ; Nitidulidae ; Carpophilus freemani
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Males ofCarpophilus freemani Dobson (Coleoptera: Nitidulidae) produce an aggregation pheromone to which both sexes fly in a wind-tunnel bioassay. The major pheromone component (ca. 30 ng per male per day in volatile collections) was identified as (2E,4E,6E)-5-ethyl-3-methyl-2,4,6-nonatriene. A minor component, (2E,4E,6E,8E)-7-ethyl-3,5-dimethyl-2,4,6,8-undecatetraene, was 3–10% as abundant as the major triene and was 5–20% as active when compared at relative doses ranging from natural proportions to 1:1. These compounds act synergistically: a mixture of major and minor components in natural proportions attracted more than twice as many beetles as the major component alone, and the mixture fully accounted for the activity of male-derived volatile collections. Six other male-derived conjugated hydrocarbons, ranging from 2% down to 0.04% as abundant as the major component, were also identified. These are (in order of decreasing bioassay activity when compared on an equal-weight basis): (3E,5E,7E)-6-ethyl-4-methyl-3,5,7-decatriene, (2E,4E,6E)-5-ethyl-3-me-thyl-2,4,6-octatriene, (3E,5E,7E,9E)-8-ethyl-4,6-dimethyl-3, 5,7,9-dodecatetraene, (2E,4E,6E,8E)-3,5,7-trimethyl-2,4,6, 8-undecatetraene, (3E,5E,7E)-5-ethyl-7-methyl-3,5,7-undecatriene, and (2E,4E,6E)-3,5-dimethyl-2,4,6-nonatriene. All structure identifications were confirmed by synthesis. In the wind tunnel, the pheromone acted synergistically with “host”-type volatiles such as propyl acetate, valeric acid, and ethanol. This concept was verified by fields tests in California, in which there was dramatic synergism between the pheromone and fermenting host materials. Pheromone biosynthesis is discussed.
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  • 50
    ISSN: 1423-0445
    Keywords: secretion-grooming ; pygidial glands ; chemical defence against microorganisms ; respiration ; aquatic beetles ; Coleoptera ; Hydradephaga ; Gyrinidae ; Haliplidae ; Noteridae ; Hygrobiidae ; Dytiscidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary All Hydradephaga investigated so far crawl onto land when exposed to an increase in water temperature and light intensity and spread the secretion from their pygidial glands over the body surface (“secretion-grooming”). The secretions have antimicrobial properties and are mainly applied to hydrofuge body regions important for aquatic respiration. Experimental prevention of secretion-grooming leads to the loss of the respiratory air bubble and a significant increase in mortality. These findings support the view that the secretion-grooming of adephagous aquatic beetles, like in some aquatic Heteroptera, inhibits the growth of microor-ganisms, thus preventing the contamination and wetting of the cuticular respiratory structures. Thus it keeps functional the air-retaining hydrophobous body regions essential for aquatic respiration. A model is presented on how secretion-grooming may have evolved in the Hydradephaga. Other possible functions of the pygidial gland secretions are discussed.
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    Chemoecology 4 (1993), S. 29-32 
    ISSN: 1423-0445
    Keywords: chemical defence ; alkaloids ; predation ; Coleoptera ; Coccinellidae ; Adalia bipunctata ; Coccinella septempunctata ; Hymenoptera ; Formicidae ; Lasius niger
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Garden black ants,Lasius niger L., in a laboratory colony, attacked three species of live ladybirds found near their nest, killing the smaller two species. A second colony was offered artificial diets containing crushed ladybirds of two species, and the ants' choice of feeding site noted. Both the diets were aversive compared to control, but that containing 7spot,Coccinella septempunctata L., was more aversive than the diet containing 2spot,Adalia bipunctata L. The implications of this lesser protection for 2spots in terms of the chemical defence of the species are discussed.
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    Cellular and molecular life sciences 46 (1990), S. 1209-1211 
    ISSN: 1420-9071
    Keywords: Pheromone ; E-myrcenol ; ipsdienol ; Ips duplicatus ; Coleoptera ; Scolytidae ; Picea abies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Males of the Eurasian bark beetleIps duplicatus, when feeding in host Norway spruce (Picea abies (L.) Karst.), produced and released ipsdienol andE-myrcenol, which we show to be aggregation pheromone components. Bioassays using walking beetles indicated thatE-myrcenol in synergistic combination with ipsdienol is essential for attraction. Synergism ofE-myrcenol and ipsdienol released at natural rates in the forest was also demonstrated with a new technique using mechanical slow-rotation of sticky traps.
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  • 53
    ISSN: 1423-0445
    Keywords: chemical defense ; predator-prey interaction ; synergism ; Coleoptera ; Staphylinidae ; Oxytelinae ; Bledius ; Carabidae ; Dyschirius ; Pogonus ; Dichirotrichus ; Formicinae ; Cataglyphis ; Dermaptera ; Labidura
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    Topics: Biology
    Notes: Summary The adaptation of defensive secretions to their target organisms was examined for the abdominal gland secretions ofBledius furcatus, B. spectabilis andB. arenarius. Therefore the target organisms of the secretion of theseBledius species (i.e. their predators) had to be identified. At the collection sites examined these were the earwigLabidura riparia, the antCataglyphis bicolor, the flyLispe candicans, different carabids of the generaPogonus, Dichirotrichus, Dyschirius, Bembidion andCalathus and the wading birdsHaematopus ostralegus andCalidris alba. The secretion of the abdominal glands contains the toxin ptoluquinone dissolved in eitherγ-dodecalactone and 1-undecene (B. furcatus andB. spectabilis) or in octanoic acid and octyloctanoate (B. arenarius). The ratio of these solvents is species-specific. Application experiments using some of the natural insect predators (L. riparia, C. bicolor, Pogonus, Di. gustavii, Dyschirius) revealed that these solvent ratios provided a more effective deterrent than other possible ratios. Thus by combining the solvents in certain ratios, the capability of cuticular penetration and therefore the effectiveness of the defensive secretions are adapted to their natural targets.
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  • 54
    ISSN: 1432-1939
    Keywords: Coleoptera ; Herbivory ; Host selection ; Maternal effect ; Paternal effect
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    Topics: Biology
    Notes: Abstract The natural host of Ophraella notulata is Iva frutescens (Asteraceae); its close relative feeds on a related plant, Ambrosia artemisiifolia. We reared beetles on both plants, obtained progeny from the four possible crosses (two sexes X two parental hosts), and reared the progeny on both plant species. Survival to the imaginal stage of progeny reared on Iva varied with both maternal and paternal host. Hatchling feeding response to both plants showed a maternal host X paternal host interaction. Consumption of Ambrosia by adult beetles was, counter to expectation, higher for progeny of Iva-reared males than Ambrosia-reared males. Oviposition response, although based on too few data to be definitive, was peculiar: parental host did not affect oviposition on Ambrosia; on Iva daughters of Iva-reared males laid significantly more eggs than did daughters of Ambrosia-reared males, but only if they had been reared on Iva; those reared on Ambrosia displayed the reverse pattern. We discuss the possibility that nongenetic paternal transmission of host plant effects may explain these results, but offer a somewhat uncomfortable hypothesis of selection as a preferable explanation. An important outcome of the experiment is that it provided no evidence of maternal effects of host plant on offspring feeding or oviposition.
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  • 55
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    Journal of nonlinear science 3 (1993), S. 477-539 
    ISSN: 1432-1467
    Keywords: nearly integrable systems ; spectral transform ; attractors ; traveling waves ; stability ; numerical methods
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    Topics: Mathematics , Physics
    Notes: Summary In this paper we rigorously show the existence and smoothness inε of traveling wave solutions to a periodic Korteweg-deVries equation with a Kuramoto-Sivashinsky-type perturbation for sufficiently small values of the perturbation parameterε. The shape and the spectral transforms of these traveling waves are calculated perturbatively to first order. A linear stability theory using squared eigenfunction bases related to the spectral theory of the KdV equation is proposed and carried out numerically. Finally, the inverse spectral transform is used to study the transient and asymptotic stages of the dynamics of the solutions.
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  • 56
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    Journal of nonlinear science 3 (1993), S. 307-327 
    ISSN: 1432-1467
    Keywords: bifurcation ; saddle node ; Hopf ; stability ; robustness ; optimization ; numerical methods ; transcritical ; pitchfork ; extended systems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Summary Engineering and physical systems are often modeled as nonlinear differential equations with a vector λ of parameters and operated at a stable equilibrium. However, as the parameters λ vary from some nominal value λ0, the stability of the equilibrium can be lost in a saddle-node or Hopf bifurcation. The spatial relation in parameter space of λ0 to the critical set of parameters at which the stable equilibrium bifurcates determines the robustness of the system stability to parameter variations and is important in applications. We propose computing a parameter vector λ* at which the stable equilibrium bifurcates which is locally closest in parameter space to the nominal parameters λ0. Iterative and direct methods for computing these locally closest bifurcations are described. The methods are extensions of standard, one-parameter methods of computing bifurcations and are based on formulas for the normal vector to hypersurfaces of the bifurcation set. Conditions on the hypersurface curvature are given to ensure the local convergence of the iterative method and the regularity of solutions of the direct method. Formulas are derived for the curvature of the saddle node bifurcation set. The methods are extended to transcritical and pitchfork bifurcations and parametrized maps, and the sensitivity to λ0 of the distance to a closest bifurcation is derived. The application of the methods is illustrated by computing the proximity to the closest voltage collapse instability of a simple electric power system.
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  • 57
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    Acta applicandae mathematicae 32 (1993), S. 59-88 
    ISSN: 1572-9036
    Keywords: 47A56 ; 47A55 ; 15A54 ; 35A30 ; 34A30 ; Operator-valued functions ; matrices ; nonself-adjoint operators ; spectrum perturbation ; eigenvalues ; stability
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    Topics: Mathematics
    Notes: Abstract A survey is presented of estimates for a norm of matrix-valued and operator-valued functions obtained by the author. These estimates improve the Gel'fand-Shilov estimate for regular functions of matrices and Carleman's estimates for resolvents of matrices and compact operators. From the estimates for resolvents, the well-known result for spectrum perturbations of self-adjoint operators is extended to quasi-Hermitian operators. In addition, the classical Schur and Brown's inequalities for eigenvalues of matrices are improved. From estimates for the exponential function (semigroups), bounds for solution norms of nonlinear differential equations are derived. These bounds give the stability criteria which make it possible to avoid the construction of Lyapunov functions in appropriate situations.
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  • 58
    ISSN: 1573-1561
    Keywords: Pheromone ; pinyon pine ; bark beetle ; cross-attraction ; Ips hoppingi ; Ips confusus ; Coleoptera ; Scolytidae ; Pinus discolor ; Pinus edulis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Females of a pinyon pine bark beetle,Ips hoppingi Lanier, were less attracted by the aggregation pheromone produced by conspecific males than by the pheromone produced by the neighboring sibling species,I. confusus (LeConte). Cross-attraction was elicited by males infesting the regional pinyon pine hosts (P. discolor andP. edulis) of eitherIps species in south-eastern Arizona. Pheromonal specificity has not accompanied speciation in this species pair.
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  • 59
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    Journal of chemical ecology 16 (1990), S. 3383-3392 
    ISSN: 1573-1561
    Keywords: Monochamus alternatus Hope ; Coleoptera ; Cerambycidae ; female ; Pinus densiflora ; Pinus thunbergii ; attractants ; (+)-juniperol ; (+)-pimaral ; sesquiterpenes ; diterpenes
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract A sesquiterpene and a diterpene were isolated from sound pines and identified as (+)-juniperol and (+)-pimaral, respectively. The combination of these compounds in a certain ratio induced a significant laboratory flight response by the female cerambycid beetle,Monochamus alternatus Hope. Individual compounds elicited a limited response only.
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  • 60
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    Journal of chemical ecology 16 (1990), S. 2203-2216 
    ISSN: 1573-1561
    Keywords: Yponomeuta cagnagellus ; caterpillars ; Lepidoptera ; Yponomeutidae ; trail following ; chemical marker ; trail pheromone ; stability ; pheromone secretory site
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Trail following in lepidopterous larvae is often attributed to chemical markers, but only a few clear-cut examples are found in the literature. In this paper evidence is presented for a chemical basis of the trail following behaviour ofYponomeuta cagnagellus. (Lepidoptera: Yponomeutidae) The marker is shown to be very persistent under laboratory conditions and is water soluble. Several possible secretory sites were investigated, and it is concluded that the marker is probably secreted together with the silk from the labial gland. Problems associated with the demonstration of trail markers in caterpillars are discussed.
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  • 61
    ISSN: 1573-1561
    Keywords: Coleoptera ; Staphylinidae ; Staphylinina ; chemical defense ; abdominal glands ; iridoids ; iridodial ; ketones ; cyclic compounds ; spiroacetals
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Forty-one volatile constituents have been characterized from the abdominal defensive glands of 13 Staphylinina rove beetle species (Staphylinidae). The major secretion component, a rapidly polymerizing iridoid dialdehyde (in most cases iridodial), is mainly accompanied by variable amounts of some iridoid lactones, traces of actinidine, some possible monoterpene precursors, short-chain ketones, cyclic compounds, and spiroacetals. The secretion mixtures even of single Staphylinina genera are very heterogenously composed of a variety of active substances with different structures. This situation may be a typical feature of iridoid defense systems based upon a primary fixative major compound and clearly differs from other chemical defense systems (for example the quinone system) which have a toxic main component.
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  • 62
    ISSN: 1573-1561
    Keywords: Glucosinolate ; sinigrin ; glucobrassicin ; sulfur ; crucifer ; Brassica juncea ; B. napus ; flea beetle ; Phyllotreta cruciferae ; Coleoptera ; Chrysomelidae ; feeding ; cotyledon
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Sinigrin (allyl glucosinolate), the major glucosinolate in the cotyledons ofBrassica juncea cv. Cutlass, occurred in the highest concentration and amount at seedling emergence and declined during growth. Glucobrassicin (3-indolylmethyl glucosinolate), the major glucosinolate in the cotyledons ofB. napus cv. Westar, occurred in the lowest concentration and amount at seedling emergence. The amount of glucobrassicin per cotyledon pair increased about fourfold during 14 days of growth, but its concentration remained relatively unchanged because of “dilution” by increasing cotyledon biomass. These different glucosinolate profiles indicate a different metabolic control and different biological function for sinigrin and glucobrassicin. The flea beetle,Phyllotreta cruciferae Goeze, does not discriminate between cotyledons having sinigrin or glucobrassicin since the two crucifers were fed upon equally in choice tests. Restricting the concentration of sulfur in the nutrient medium accelerated the decline of sinigrin inB. juncea cv. Cutlass but did not alter the feeding rate ofP. cruciferae compared to controls. Sulfur restriction reduced glucobrassicin inB. napus cv. Westar to undetectable levels and somewhat reduced the feeding rate of P.Cruciferae. Nevertheless,P. cruciferae still fed actively on cotyledons ofB. napus cv. Westar depleted of glucosinolates and severely damaged many of them. Since glucosinolate type and concentration had little effect on feeding response, reduction or elimination of foliar glucosinolates alone would not seem a useful strategy for protecting seedlings of these two crucifers from flea beetle damage.
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  • 63
    ISSN: 1573-1561
    Keywords: Colorado potato beetle ; Leptinotarsa decemlineata ; Coleoptera ; Chrysomelidae ; S. berthaultii ; S. tuberosum ; trichome ; antifeedant ; resistance
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The leaf extract fromS. berthaultii Hawkes (PI 473340) contains exudate from trichomes (type B). Consumption ofS. tuberosum var. Norchip foliage by the Colorado potato beetleLeptinotarsa decemlineata (Say) was reduced when treated with the leaf extract. The leaf extract from a resistantS. berthaultii clone without type B trichome had no antifeedant activity. It suggests that more than one mechanism of resistance to the Colorado potato beetle exists inS. berthaultii.
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  • 64
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    Journal of chemical ecology 16 (1990), S. 1921-1925 
    ISSN: 1573-1561
    Keywords: Lesser grain borer ; Rhyzopertha dominica (F) ; Coleoptera ; Bostrichidae ; aggregation pheromone ; chiral synthesis
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract (S)-(+)-1-Methylbutyl (E)-2-methyl-2-pentenoate,1, and (S)-(+)-1-methylbutyl (E)-2,4-dimethyl-2-pentenoate2, the aggregation pheromone for lesser grain borerRhyzopertha dominica (F). were synthesized from crotylaldehyde in an overall yield of 30%. The chiral intermediate6 was prepared in 90% enantiomer excess, employing the Sharpless asymmetric epoxidation.
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  • 65
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    Journal of chemical ecology 16 (1990), S. 2589-2604 
    ISSN: 1573-1561
    Keywords: Trypodendron lineatum ; ambrosia beetle ; Coleoptera ; Scolytidae ; semiochemicals ; flight behavior ; wind tunnel ; drainpipe trap
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The responses of the striped ambrosia beetle,Trypodendron lineatum (Olivier) (Coleoptera: Scolytidae), to modified drainpipe traps baited with the host attractant ethanol, the aggregation pheromone lineatin, both alone and in combination, were studied in a wind tunnel. Exposure of males to ethanol increased their frequency of steady, upwind flight; however, only lineatin was effective in inducing them to land on and enter the traps. In contrast, exposure of females to either ethanol or lineatin alone resulted in an increased frequency of trap landing and entry. Both compounds released simultaneously did not significantly increase the frequency of trap landing and entry for either sex. These responses are consistent with the life history strategies used by both sexes to seek and colonize suitable host material.
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  • 66
    ISSN: 1573-1561
    Keywords: Encelia farinosa ; Asteraceae ; Trirhabda geminata ; Coleoptera ; Chrysomelidae ; feeding preferences ; acidic deposition ; plant stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Container grownEncelia farinosa were exposed to three 3-hr episodes of acidic fog (pH 2.5) typical of events in southern California. Adults and larvae of the specialist leaf-feeding herbivore,Trirhabda geminata, preferred to feed on the acidic-treated foliage compared to control fogged (pH 6.3–6.5) foliage. Previous feeding damage on the plants did not affect feeding preference. The acidic-fogged foliage was significantly higher in total nitrogen and soluble protein but not different from control-treated tissue in water content. Stress on native populations of this drought-deciduous shrub caused by atmospheric pollutants may also result in altered feeding ecology of the beetle.
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  • 67
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    Journal of chemical ecology 19 (1993), S. 395-410 
    ISSN: 1573-1561
    Keywords: Oreina gloriosa ; Coleoptera ; Chrysomelidae ; chemical defense ; cardenolides ; quantitative variation ; aging ; HPLC
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The defensive secretion of the alpine chrysomelidOreina gloriosa is a complex mixture of mainly cardenolides and tyrosine betaine. Individually sampled secretions of adult laboratory-reared and field-collected beetles were analyzed by reverse-phase HPLC; 16 secretion components were quantified. Quantities and concentrations of different components were significantly affected by the age, sex, and reproductive status of individual beetles. Aging was correlated with marked increases (up to 4.4-fold) and decreases (up to 2.7-fold) of quantities and concentrations of several components. Differences between the sexes were smaller, but quantities of all components and concentrations of several components were larger in laboratory-reared females than in males. There was less of one component of the secretion in mated than unmated females, but the concentrations of four secretion components were higher (up to 1.6-fold) in mated females.
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  • 68
    ISSN: 1573-1561
    Keywords: Rapeseed ; Brassica spp. ; allyl isothiocyanate ; glucosinolates ; allelochemicals ; Limonius californicus (Mann.) ; Coleoptera ; Elateridae ; toxicity ; sublethal effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Acute toxicity of soil amended with allyl isothiocyanate (AITC) to three size classes ofLimonius californicus (Mann.) wireworms was determined in the laboratory. Wireworms were exposed to AITC at initial concentrations of 120–300 nmol/g soil for one day. During this time, extractable AITC concentrations decreased by 66 to 93 %. Probit analysis estimated LC50 values of 238 and 226 nmol/g soil at one day posttreatment for medium and large wireworms, respectively. For small wireworms, LC50 values decreased from 211 to 157 nmol/g soil during 1–137 days posttreatment. Sublethal concentrations of AITC significantly reduced feeding activity of treated wireworms at three posttreatment times and over the entire 137 days. Wireworm weight was not significantly affected by AITC. The potential exists to use glucosinolate-containing plant tissue as an isothiocyanate (ITC) source to reduce crop damage caused byL. californicus wireworms.
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  • 69
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    Journal of chemical ecology 19 (1993), S. 1219-1231 
    ISSN: 1573-1561
    Keywords: Host recognition behavior ; entomopathogenic nematodes ; feces ; Spodoptera exigua ; Lepidoptera ; Noctuidae ; Popillia japonica ; Coleoptera ; Scarabaeidae ; Blattella germanica ; Blatteria ; BlattellidaeAcheata domesticus ; Orthoptera ; Gryllidae
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Host recognition by entomopathogenic nematodes may occur through contact with insects' excretory products, cuticle, or gut contents. We analyzed the behavioral responses of four species of entomopathogenic nematodes during contact with feces of natural or experimental hosts. Host recognition by nematodes was manifested in alterations in the frequency and/or duration of one or more search parameters including forward crawling, headwaving, body-waving, stopping, backward crawling, head-rubbing, and headthrusting.Heterorhabditis bacteriophora andSteinernema glaseri showed behavioral responses to contact with feces of their natural hosts,Spodoptera exigua (Lepidoptera) andPopillia japonica (Coleoptera), and to the experimental hosts,Acheata domesticus (Orthoptera) andBlatella germanica (Blatteria).Steinernema carpocapsae responded only toB. germanica feces, whereas5. scapterisci did not significantly respond to any of the insect species. During contact with cockroach feces, all nematodes, exceptS. scapterisci, showed avoidance behavior. We suggest that ammonia present in cockroach feces is inhibitory to nematodes. Specific host recognition by entomopathogenic nematodes may be an important mechanism to maintain host affinities.
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  • 70
    ISSN: 1573-1561
    Keywords: Holotrichia parallela ; large black chafer ; scarab beetle ; Coleoptera ; Scarabaeidae ; isoleucine methyl ester ; linalool ; sex pheromone ; circabidian periodicity ; pheromone titer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract (R)-(−)-Linalool was identified as a minor component sex pheromone of the scarab beetleHolotrichia parallela (Coleoptera: Scarabaeidae). Field evaluations revealed that, although not attractive per se, (R)-(−)-linalool enhances the attractiveness of the major sex pheromone,L-isoleucine methyl ester (LIME). Analyses of the pheromone titers in the glands of field-collected females demonstrated the occurrence of peak levels of 48-hr (“circabidian”) periodicity. The levels of LIME in the glands of 45-day-old virgin females increased over three times from the scototo the photophase of a calling day, but the amounts of (R)-(−)-linalool did not significantly change. Virgin females had in average two times more LIME and 3.6 times more (R)-(−)-linalool than the average amount found in the field-captured beetles throughout the season.
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  • 71
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    Journal of chemical ecology 19 (1993), S. 1453-1459 
    ISSN: 1573-1561
    Keywords: Anomala schonfeldti ; Popillia japonica ; scarab beetle ; Coleoptera ; Scarabaeidae ; 2-(E)-nonenol ; sex pheromone ; mark-and-recapture ; field test ; mass trapping
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Synthetic 2-(E)-nonenol, previously identified as the sex pheromone ofAnomala schonfeldti (Coleoptera: Scarabaeidae), is demonstrated to be very attractive to males in the field. Nevertheless, no significant differences were found between treatments with 1, 5, 10, and 20 mg dosages. Males ofA. schonfeldti were more significantly attracted to traps at 30 cm high than at 90 cm. Although the observed behavior seemed to indicate a trend of more attraction to buried traps than those placed at 30 cm, there was no statistical difference between the two treatments. Pheromone-baited traps caught significantly more beetles than traps containing three virgin females. Over 70% of released beetles were recaptured in six traps surrounding the point of release and separated from each other by 50 m, suggesting a possible use of the pheromone (in combination with floral compounds) in mass trapping.
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  • 72
    ISSN: 1573-1561
    Keywords: Coleoptera ; Staphylinidae ; Tenebrionidae ; larvae ; defensive glands ; quinone ; naphthoquinone ; taxonomy
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The abdominal glands of three bark-inhabiting larvae of generaBolitochara, Leptusa (Staphylinidae), andHypophloeus (Tenebrionidae) were studied chemically and morphologically. Behavior of the larvae indicated that secretion is emitted only after severe disturbance of the larvae. These mechanical contacts may also occur incidentally with coinhabiting nonpredatory arthropods when the beetle larvae move within small interstices under bark. Depending on the species, the secretions contained 1,4-benzoquinone derivatives and three 6-alkyl-naphthoquinones dissolved within various alkanes, alkenes, ethyl-, isopropyl-, and isoamylesters. More erratically distributed gland constituents also detected were acetophenone, benzyl propionate, and methyl hydroxybenzoate. In the laboratory, synthetic quinone-containing solutions simulating those found inLeptusa andBolitochara larvae acted as strong topical irritants and caused further damage to last-stageCalliphora vomitoria larvae if hydrocarbons or esters were used as solvents. The natural secretions ofHypophloeus versipellis elicited considerable mortality in two subcortical sciarid larvae cooccurring with tenebrionid larvae. Bioassay and secretion chemistry of the Staphylinidae/Tenebrionidae larval secretions indicated that they are typical defensive secretions that act topically. Morphological data characterized Bolitocharini larvae as possessing protuberant abdominal tergites supplied with an interiorly situated gland reservoir. After mechanical contact, the defensive secretion is topically applied to other arthropods by dabbing this tergal protuberance on targets. The defensive gland ofHypophloeus versipellis is unusual in possessing a movable reservoir opening situated at the anterior border of tergite IX. By this peculiar gland morphologyHypophloeus larvae are capable of shooting secretion droplets frontally from their slightly depressed dorsal abdominal surface without bending their abdominal tips dorsally. This seems an adaptation to the interstitial habitat of the larvae. The types of defensive glands and their phylogenetic value in Aleocharinae/Tenebrionidae larvae are discussed.
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  • 73
    ISSN: 1573-1561
    Keywords: Hylastes cunicularius ; Hylastes brunneus ; Hylastes opacus ; Dryocoetes autographus ; Hylobius abietis ; Hylobius pinastri ; α-pinene ; terpenes ; turpentine ; ethanol ; ground traps ; Coleoptera ; Scolytidae ; Curculionidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Responses of threeHylastes species,Dryocoetes autographus, and twoHylobius species to terpenes and ethanol were studied in field experiments on clear-cut forest sites in Sweden using baited ground traps.α-Pinene alone did not attract any of the six species. A terpene blend (spruce turpentine consisting mainly ofα-pinene,β-pinene, and 3-carene) attractedHylastes cunicularius, H. brunneus, andHylobius abietis in some experiments, but not in others. The attractiveness of ethanol also varied; the only species consistently attracted wasH. abietis. Baits containing both terpenes and ethanol, particularly the combination of spruce turpentine and ethanol, were attractive to all species exceptHylobius pinastri. InH. abietis, the terpene plus ethanol/ ethanol catch ratios increased during early summer. Seasonal differences in catch levels were observed inH. cunicularius andH. abietis. The addition ofα-pinene reduced the attractiveness of the combination of spruce turpentine and ethanol toH. cunicularius, H. opacus, andD. autographus. The differences in response to the volatiles between species are probably related to differences in reproductive behavior and host preferences.
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  • 74
    ISSN: 1573-5028
    Keywords: antinutritional factor ; pea lectin ; site-directed mutagenesis ; stability
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    Topics: Biology
    Notes: Abstract Legume lectins are considered to be antinutritional factors (ANF) in the animal feeding industry. Inactivation of ANF is an important element in processing of food. In our study on the stability ofPisum sativum L. lectin (PSL), a conserved hydrophobic amino acid (Val103) in a surface loop was replaced with alanine. The mutant lectin, PSL V103A, showed a decrease in unfolding temperature (T m ) by some 10 °C in comparison with wild-type (wt) PSL, and the denaturation energy (ΔH) is only about 55% of that of wt PSL. Replacement of an adjacent amino acid (Phe104) with alanine did not result in a significant difference in stability in comparison with wt PSL. Both mutations did not change the sugarbinding properties of the lectin, as compared with wt PSL and with PSL from pea seeds, at ambient temperatures. The double mutant, PSL V103A/F104A, was produced inEscherichia coli, but could not be isolated in an active (i.e. sugar-binding) form. Interestingly, the mutation in PSL V103A reversibly affected sugar-binding at 37 °C, as judged from haemagglutination assays. These results open the possibility of production of lectins that are activein planta at ambient temperatures, but are inactive and possibly non-toxic at 37 °C in the intestines of mammals.
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  • 75
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    Acta mechanica Sinica 9 (1993), S. 277-288 
    ISSN: 1614-3116
    Keywords: generalized hybrid/mixed model ; element formulation ; equilibrium ; orthogonality ; least energy fit ; convergence ; stability ; coordinate invariance ; distortion insensitivity ; accuracy
    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 the modified three-field Hu-Washizu principle, this paper establishes a theoretical foundation and general convenient formulations to generate convergent stable generalized hybrid/mixed element (GH/ME) model which is invariant with respect to coordinate, insensitive to geometric distortion and suitable for improved stress computation. In the two proposed formulations, the stress equilibrium and orthogonality constraints are imposed through incompatible displacement and internal strain modes respectively. The proposed model by the general formulations in this paper is characterized by including assumed stress/strain, assumed stress, variable-node, singular, compatible and incompatible GH/ME models. When using regular meshes or the constant values of the isoparametric Jacobian Det in the assumed strain interpolation, the incompatible GH/ME model degenerates to the hybrid/mixed element model. Both general and concrete guidelines for the optimal selection of element shape functions are suggested. By means of the GH/ME theory in this paper, a family of new GH/ME can be and have been easily constructed. The software can also be developed conveniently because all the standard subroutines for the corresponding isoparametric displacement elements can be utilized directly.
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  • 76
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    Acta mechanica Sinica 6 (1990), S. 15-21 
    ISSN: 1614-3116
    Keywords: transition ; compliant wall ; stability
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract In a previous paper[1], a method has been developed to study the stability characteristics of laminar boundary layers over compliant walls. In this paper, the effect of double layered compliant wall and Kramer type compliant wall on delaying the transition is investigated, and it is shown that there does exist the possibility to delay the transition by applying such compliant walls.
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  • 77
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    Applied mathematics and mechanics 14 (1993), S. 95-100 
    ISSN: 1573-2754
    Keywords: discrete large-scale systems ; stability ; Liapunov function
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Mathematics , Physics
    Notes: Abstract In this paper, we directly use the linear norm Liapunov function to investigate the stability of the linear discrete large-scale systems and obtain some criteria for the asymptotic stability of such a system.
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  • 78
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    Applied mathematics and mechanics 14 (1993), S. 981-982 
    ISSN: 1573-2754
    Keywords: Burgers shock wave ; infinitesimal disturbance ; stability ; asymptotically stable
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Mathematics , Physics
    Notes: Abstract This paper considers the stability of the Burgers shock wave solution with respect to infinitesimal disturbance. It is found that the Burgers shock wave is asymptotically stable in the Liapunov sense.
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  • 79
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    Pharmaceutical research 10 (1993), S. 156-159 
    ISSN: 1573-904X
    Keywords: aspirin ; hydroxypropyl-β-cyclodextrin ; complexation ; stability ; activation energies
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    Topics: Chemistry and Pharmacology
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  • 80
    ISSN: 1573-904X
    Keywords: CI-981 ; HMG-CoA reductase inhibitor ; stability ; solubility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The pH dependence of the interconversion kinetics, equilibrium, and solubilities of the lactone and hydroxyacid forms of the HMG-CoA reductase inhibitor, CI-981 ([R-(R*,R*)]-2-(4-fluorophenyl)-β,δ-dihydroxy-5-(l-methylethyl)-3-phenyl-4-[(phenylamino)carbonyl]-lH-pyrrole-l-hepatonic acid), are important considerations when chosing and developing one of the forms of these compounds. Over a pH range of 2.1 to 6.0 and at 30°C, the apparent solubility of the sodium salt of CI-981 (i.e., the hydroxyacid form) increases about 60-fold, from 20.4 µg/mL to 1.23 mg/mL, and the profile yields a pK a for the terminal carboxyl group of 4.46. In contrast, over a pH range of 2.3 to 7.7 and also at 30°C, the apparent solubility of the lactone form of CI-981 varies little, and the mean solubility is 1.34 (±0.53) µg/mL. The kinetics of interconversion and the equilibrium between the hydroxyacid and the lactone forms have been studied as a function of pH, buffer concentration, and temperature at a fixed ionic strength (0.5 M) using a stability-indicating HPLC assay. The acid-catalyzed reaction is reversible, whereas the base-catalyzed reaction can be treated as an irreversible reaction. More specifically, at pH 〈6, an equilibrium favoring the hydroxyacid form is established, whereas at pH 〉6, the equilibrium reaction is no longer detectable and greatly favors the hydroxyacid form. The rate constant for lactone formation, k 1 is well described by specific acid-catalyzed and spontaneous lactonization pathways, whereas the rate constant for lactone hydrolysis (or hydroxyacid formation), k 2, is well described by specific acid-, water-, and specific base-catalyzed pathways.
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  • 81
    ISSN: 1573-904X
    Keywords: emulsions ; stability ; field-flow fractionation ; size distribution
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    Topics: Chemistry and Pharmacology
    Notes: Abstract The combination of sedimentation field-flow fractionation (SedFFF) and photon correlation spectroscopy (PCS) is shown to provide a detailed record of the droplet sizes present in fat emulsions commonly used in parenteral nutrition. The technique presented has been used to record size distribution data for a particular emulsion (Liposyn-II), demonstrating its high stability and lot-to-lot uniformity. The technique is also able to demonstrate how additions of small amounts of electrolytes [0.45% (w/v) NaCl, 0.05% (w/v) CaCl2] tend to destabilize the emulsion, suggesting some caution in the use of total parenteral nutrition (TPN) mixtures. In contrast, a 1:1 mixture with human serum caused no sign of instability in the Liposyn-II. Using the emulsion as a carrier for lipophilic drugs necessitates adding solutions of the drug in nonaqueous solvents, such as DMSO (dimethyl sulfoxide). This solvent's destabilizing effect results in a droplet coalescence that becomes severe after 3–5 days following a 10% (v/v) addition, while a 5% (v/v) addition reaches the same level of coalescence in 10 days.
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  • 82
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    Pharmaceutical research 10 (1993), S. 1174-1180 
    ISSN: 1573-904X
    Keywords: aspartame ; stability ; pH – rate profile ; peptide ester ; hydrolysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The kinetics of demethylation of aspartame and L-phenylalanine methyl ester were studied in aqueous solution at 25°C over the pH range 0.27–11.5. The pseudo-first-order rate constant for aspartame was resolved into individual contributions from methyl ester hydrolysis and diketopiperazine formation. pH – rate profiles were quantitatively described by chemically reasonable kinetic schemes. Aspartame is maximally stable at pH 4 (t 90 = 53 days at 25°C); phe-nylalanine methyl ester, at pH 3. The potentiometrically measured pK a values were pK a1 3.19 and pK a2 7.87 fr aspartame and pKa 7.11 for phenylalanine methyl ester.
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  • 83
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    Pharmaceutical research 10 (1993), S. 1466-1470 
    ISSN: 1573-904X
    Keywords: p-chloro-m-xylenol ; 4-chloro-3,5-dimethylphenol (PCMX) ; radiolabel synthesis ; isotopes ; stability ; reaction kinetics ; in vitro studies
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    Topics: Chemistry and Pharmacology
    Notes: Abstract The synthesis, reaction kinetics, and pH stability of isotopically labeled p-chloro-m-xylenol (PCMX) were evaluated. While base catalysis was more rapid than acid catalysis, the latter allowed the use of a cosolvent for deuterium and tritium labeling using as little as 250 µL labeled water. Both acid and base catalysis were markedly more rapid than that reported previously for the deuteration of PCMX and related phenols. Isotopic labeling occurred only at the 2 and 6 ring positions, ortho to the phenolic group of PCMX. No deuterium loss was observed after storage for 21 days at 37°C over a pH range of 2 – 14. Isotopic loss was observed only below pH 2. The prepared 3H-labeled PCMX had a specific activity of 1.18 mCi/mmol, a radiochemical purity of 99.0%, and a chemical purity exceeding 99.0%, with a high stability during prolonged cold storage.
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  • 84
    ISSN: 1573-904X
    Keywords: α-chymotrypsin ; fatty acid ; insulin ; mixed micelles ; proteolytic degradation ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The proteolytic degradation of porcine zinc insulin by α-chymotrypsin was previously found to depend markedly on the state of insulin aggregation (Pharm. Res. 9:864–869, 1992). In this study, the effect of bile salt-unsaturated fatty acid mixed micelles on α-chymotryptic degradation of insulin was further characterized. The incorporation of linoleic acid has greatly accelerated insulin degradation with the apparent first order rate constant being linearly related to the concentration of linoleic acid. At a 10 mM linoleic acid concentration solubilized in 10 mM sodium glycocholate, the proteoly tic degradation rate constant increased by 16 times, which could not be explained solely by the mechanism of insulin oligomer dissociation. Further, this effect is significantly reduced when the free carboxylic group of linoleic acid is methylated. The catalytic role of mixed micelles on chemical degradation of insulin was found to depend on the concentration of linoleic acid incorporated. When solubilized in the form of mixed micelles, linoleic acid chemically catalyzes peptide bond cleavage in a concentration-dependent manner.
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  • 85
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    Plant systematics and evolution 173 (1990), S. 143-157 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Winteraceae ; Zygogynum ; Lepidoptera ; Micropterigidae ; Sabatinca ; Coleoptera ; Pollination biology ; coevolution ; floral volatiles ; parallel radiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Flower visitors on 12 species of New CaledonianWinteraceae were studied. The visitors were two species of ancestral moths (Sabatinca; Micropterigidae), three species of weevils (Palontus; Curculionidae), and a species of thrips. Behavior observations and pollen records suggest that the beetles and occasionally the moths serve as pollinators ofZygogynum and Exospermum, andBelliolum is pollinated primarily by thrips. The floral volatiles are simple in composition, usually dominated by short esters. Preliminary experiments showed that ethyl acetate elicited alighting, and a distinctive huddling behavior was elicited by artificially mixed fragrance. The host associations of otherSabatinca andPalontus spp. do not support the hypothesis that theWinteraceae have radiated in association with their pollinators. The available evidence supports the notion of opportunistic isolated host colonizations at some point in the radiation of the pollinator groups.
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  • 86
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    Colloid & polymer science 271 (1993), S. 793-798 
    ISSN: 1435-1536
    Keywords: Cholesterol colloids ; surfactants ; surface charge ; zeta potential ; stability ; shape ; size ; viscosity
    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 Cholesterol colloids stabilised by Tween 20 (Colloid I), SDS-Et4 NBr (Colloid II), and CTAB-Nac (Colloid III) were prepared. Moving boundary electrophoresis established Colloid III to be positively charged with a zeta potential of 12.2 mV. Addition of 5 mmol dm−3 Na2SO4 and 0.1 mmol dm−3 bilirubin dye (Na-salt) decreased the zeta potential to 9.7 mV and 9.5 mV, respectively, by screening the surface charge of the colloidal particles. Higher concentrations of Na2SO4 and bilirubin (Na-salt) made making electrophoretic measurements difficult, and such a situation was also faced in the case of Colloid II even without external addition of an electrolyte. Addition of several electrolytes revealed that Colloids II and II were coagulated by the neutralisation of their positive charge, but Colloid I was destabilised by salting-out effect. Measured intrinsic viscosity values and electron microscopic measurements supported overall spherical shape of the colloid particles. Colloid II exibited structural viscosity; higher concentration of NaSO4 decreased the viscosities of Colloid II and II by electroviscous effect which helped indirect determination of the electrokinetic potential (23.7 mV) of Colloid II.
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  • 87
    ISSN: 1573-5044
    Keywords: Datura stramonium ; hairy roots ; hyoscyamine ; tropane alkaloids ; scopolamine ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The aim of this paper was the screening of the variability of growth patterns, biomass and tropane alkaloid production of 500 hairy root lines ofDatura stramonium. Data on the long term stability in alkaloid production of these lines for more than 5 years are also provided. In an effort to obtain high alkaloid-producing root clones, it is demonstrated that systematic selection is necessary. Comparisons are made, mainly concerning alkaloid production and its stability, with normal root cultures initiated from the same mother plants when necessary. Hairy root cultures were found to have a hyoscyamine and scopolamine bioproductivity of 2 orders of magnitude higher than mother plants.
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  • 88
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    Euphytica 71 (1993), S. 231-238 
    ISSN: 1573-5060
    Keywords: sweet potato ; Ipomoea batatas ; stability ; joint regression analysis ; G x E interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Two experiments, each involving a set of 10 sweet potato clones, were conducted for three years at 4 sites (Ekona, Ebolowa, Nkolbisson, and Bambui Plain) in Cameroon. Data obtained were subjected to analysis of variance to determine the presence of genotype x environment (G x E) interactions, and to regression analysis to assess the performance of clones across anvironments. Environments were assessed in two ways: (i) the mean response of all clones (dependent assessment), and (ii) the average performance of a different set of clones (independent assessment). The first experiment (Expt 1) produced higher yields but had fewer stable clones than the second (Expt 2). The analysis of variance revealed that the clones interacted significantly with environments for all traits. The study has identified high yielding and stable sweet potato clones for distribution to growers in the major areas of cultivation in the tountry. Despite slight differences in numbers of clones judged stable by the various regression indices in the two methods of environmental assessments, the rankings of clones on the basis of their linear regression coefficients were similar. In a developing country like Cameroon, with limited resources and where sophisticated equipment for obtaining physical or biological measures of the environment may be lacking, the mean performance of genotypes may still be the most reliable measure of environment in evaluating the stability of performance of crop cultivars.
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  • 89
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    Euphytica 49 (1990), S. 243-247 
    ISSN: 1573-5060
    Keywords: hybrid rice ; cytoplasmic genetic male sterile line ; fertility restorer ; heterosis ; heterobeltiosis ; standard heterosis ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary One hundred and thirtysix hybrids were developed utilizing four cytoplasmic genetic male sterile lines (V 20A, Zhen Shan 97A, IR 46829A and IR 46830A) and 34 effective restorers. Heterosis, heterobeltiosis and standard heterosis were found to be significant for grain yield and other yield attributing characters in most of the hybrids. The heterosis for grain yield was mainly due to the significant heterosis for the number of spikelets per panicle, test weight and total dry matter accumulation. Interestingly, it was found that most of the higher yielding hybrids were accompanied by significant negative heterosis for harvest index. Hybrids shorter than the shortest parent and earlier than the earliest parent were not observed; hybrids with intermediate to tall plant height having nonlodging habit could be developed. Eighteen hybrids gave more than 20% grain yield than the standard checks. These were evaluated for their stable and consistent yield performance over four seasons. The results on analysis for stability parameters indicated that the hybrids V 20A × Himdhan and Zhen Shan 97A × Mahsuri were stable over environments.
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  • 90
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    Hydrobiologia 204-205 (1990), S. 15-16 
    ISSN: 1573-5117
    Keywords: community ; disturbance ; harvesting ; population ; recruitment ; seaweed ; stability
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    Topics: Biology
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  • 91
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    Hydrobiologia 190 (1990), S. 263-266 
    ISSN: 1573-5117
    Keywords: Sediments ; stability ; sedimentation ; infauna
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    Topics: Biology
    Notes: Abstract Secretions produced by the two estuarine benthic invertebrates Corophium volutator and Nereis diversicolor stabilise sediments by increasing their shear strength, and reduce sedimentation of previously resuspended particles. The secretions consist of 1 to 2 μm threads which bind the particles together. They are used by both species in the production of complex burrow systems in the top 15 cm of sediment. The burrow systems have been demonstrated by a new resin impregnation technique. These results have widespread implications for the stability and erosion of estuarine sediments.
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  • 92
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    Geotechnical and geological engineering 11 (1993), S. 81-105 
    ISSN: 1573-1529
    Keywords: Rock discontinuities ; uniaxial compression ; fracture mechanics ; stability ; scale effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Summary Five series of test blocks of Pendeli marble with artificially created discontinuities of different crack densities (simulating three mutually orthogonal joint sets) were tested in uniaxial compression in order to study the effect of discontinuities on: (a) the compressive strength and the modulus of elasticity, and (b) certain fracture energy parameters expressed by the ratio W A/W V, where W A is the surface energy and W V the volume elastic strain energy. Mathematical relationships are derived similar to those suggested by other authors relating strength parameters to crack densities. Such relationships clearly show a reduction in strength with increased crack density. The experimental results obtained permit the extension of Persson's relation (which refers to ideal intact rock) to the more realistic case of discontinuous rock mass by introducing the appropriate term that takes into consideration the effect of rock mass discontinuities on the energy ratio W A/W V. A comparison between laboratory results and field observations was subsequently carried out assuming the rock mass to behave as a linearly elastic material, obeying the Hoek and Brown failure criterion. This comparison showed that laboratory results can be extended to larger scale. Furthermore, in order to predict the in situ strength and stability of a rock mass in uniaxial compression (which is of major importance in underground excavations) certain concepts are proposed based on laboratory tests, in situ investigations and first principles of linear elastic fracture mechanics.
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  • 93
    ISSN: 1573-1561
    Keywords: Repellency ; volatile fatty acids ; propionic acid ; butyric acid ; valeric acid ; yellow mealworm ; Tenebrio molitor ; Coleoptera ; Tenebrionidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Frass of late-instar larvae ofTenebrio molitor L. contained 0.0889 g of butyric acid, 0.0279 g of propionic acid, and 0.0175 g of valeric acid per 100 g. Grouped larvae were strongly repelled by butyric acid at the 10−1 M concentration. Lower concentrations of butyric acid were less repellent. Valeric acid was repellent at 10−1 M to 10−3 M concentrations, below which no tested concentration, including one identical to that occurring in prepared solutions of frass found to be attractive, displayed any effect. Propionic acid was repellent at the concentration in prepared solutions of frass, which were strongly attractive. Concentrations of 10−1 M, 10−3 M, and 10−4 M propionic acid were also found to be repellent. The implications of the repellency of these compounds to groups of mealworm larvae are discussed, with particular reference to the interaction between these frass components and others that have already been studied.
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  • 94
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    Journal of chemical ecology 16 (1990), S. 757-772 
    ISSN: 1573-1561
    Keywords: Cotton ; Gossypium spp ; boll weevil ; Anthonomus grandis ; Coleoptera ; Curculionidae ; oviposition ; plant-insect interaction ; terpenoids ; sugars
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Several cottonGossypium spp. race stocks have been identified that possess resistance to the boll weevilAnthonomus grandis Boh. because oviposition is decreased. In this work, a number of known cotton constituents that influence stimulation of feeding and attractancy for this insect were found to have little or no influence on oviposition. These include gossypol, β-bis-abolol, caryophyllene, some fatty acids and their methyl esters, some wax esters, flavonoids, condensed tannins, and chrysanthemin. Analysis of cotton bud surfaces showed that the content of volatile terpenoids was generally higher in resistant lines, but bioassays did not show decreased oviposition in the presence of the terpenoids. The sugars (glucose, fructose, and sucrose) found in anthers, uniformly stimulated oviposition in the bioassay, and their content was higher in susceptible lines. These results suggest that a major basis of resistance to boll weevils as related to oviposition may be the decreased content of sugars in resistant lines. The analysis of free sugars in the anthers, and perhaps also the analysis of bud surface terpenoids, may provide a basis for selection or genetic production of cotton lines resistant to the boll weevil.
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  • 95
    ISSN: 1573-1561
    Keywords: Pheromone ; bark beetle ; Coleoptera ; Scolytidae ; Pityogenes chalcographus ; methyl (E,Z)-2,4-decadienoate ; chalcogran ; Picea abies ; synergist ; subtractive-combination bioassay ; two-dimensional fractionation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Capillary gas chromatography with columns of different polarity and two-dimensional fractionation of effluents were used with novel subtrac-tive-combination bioassays to rigorously isolate host- and insect-produced pheromone synergists of the bark beetlePityogenes chalcographus (Coleop-tera: Scolytidae). Methyl (E,Z)-2,4-decadienoate (E,Z-MD) and the previously identified chalcogran were found to be synergistically attractive to both sexes.E,Z-MD was produced sex-specifically in males, and only when they had fed on host-plant tissue. A Norway spruce monoterpene fraction (including α-pinene, β-pinene, and camphene) increased the attractive response to the pheromone components. Dose-response curves forE,Z-MD and chalcogran in the laboratory bioassay indicated the two components are highly synergistic. The isolation methods are important for further progress in identifying certain semiochemical synergists found in trace amounts in complex chemical mixtures, such as when insects must feed in host plants in order to produce pheromone.
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  • 96
    ISSN: 1573-1561
    Keywords: Oviposition deterrent ; serricorone ; cigarette beetle ; Lasioderma serricorne ; Coleoptera ; Anobiidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Oviposition deterrents of the cigarette beetle,Lasioderma serricorne, were isolated from its adult body extract and found to be identical to (2S,3R,1'S)-2,3-dihydro-3,5-dimethyl-2-ethyl-6-(l′-methyl-2′-oxobutyl)-4H-pyran-4-one (α-serricorone) and its l′R-epimer (β-serricorone) by spectroscopic evidence. Serricorone was previously found as one of the minor sex pheromone components of the same insect, and hence indicating bi-functional nature. The presence of two isomers in the body was proved by careful treatment. Each of them exhibited the same level of oviposition deterring activity, which was less potent than the crude body extract at an increased concentration.
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  • 97
    ISSN: 1573-1561
    Keywords: Perennial ryegrass ; Lolium perenne ; Gramineae ; Argentine stem weevil ; Listronotus bonariensis ; Coleoptera ; Curculionidae ; Acremonium lolii ; endophyte ; feeding deterrent ; peramine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Peramine, a pyrrolopyrazine alkaloid produced by the fungal endophyte of perennial ryegrassAcremonium lolii, deterred the feeding of both adults and larvae of the graminacious herbivore, the Argentine stem weevil (Listronotus bonariensis), at 0.1 μg/g and 10 μg/g, respectively. In a no-choice test fewer stem weevil larvae fed and developed on diet containing as little as 2 μg/g peramine. The proportion of larvae which did not develop beyond the first instar was higher on diet containing peramine and appeared to be due to a higher proportion of larvae which did not feed. For larvae which fed on the peramine-containing diet, feeding scores and times to pupation were not significantly different from those of controls. A number of simple peramine analogues showed feeding-deterrent activity against adult weevils, indicating the importance of the pyrrolopyrazine ring system of peramine in determining feeding-deterrent activity.
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  • 98
    ISSN: 1573-1561
    Keywords: Cylas formicarius elegantulus (Summers) ; Coleoptera ; Curculionidae ; sex pheromone ; sweetpotato weevil ; mark-release-recapture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Studies were conducted to determine the effects of sex pheromone dosage and lure age on movement of male sweetpotato weevils (SPW),Cylas formicarius elegantulus (Summers), using mark-release-recapture techniques. SPW trap counts from various downwind distances were compared for dosages ranging from 0.01 to 10.0 μg and lure ages ranging from fresh (0 days old) to 64 days old. The percentages of male SPW recaptured decreased with an increase in release distance and decreased with a decrease in dosage at each corresponding distance. Most SPW were caught within the first 16-hr period. Slopes of percent recapture vs. release distance for the two higher dosages (10 μg and 1.0 μg) differed from those of the two lower dosages (0.1 and 0.01 μg) but did not differ from each other. Intercepts were similar among the three higher dosages. Slopes did not differ among the five lure ages examined. Intercepts differed between fresh (0 days old) and 24-day-old septa at 16 hr and between fresh (0 days old) and 34-day-old septa at 40 hr. Previous exposure to pheromone (conditioning) did not increase percentages of SPW recaptured. Results indicate that male SPW are capable of traversing distances of at least 280 m in 16 hr. The pheromone tested in this study appears to be effective at dosages lower than any other coleopteran sex-pheromone system. Incorporation of this pheromone into a SPW management system may effectively reduce the use of insecticides.
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  • 99
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    Journal of chemical ecology 16 (1990), S. 2519-2531 
    ISSN: 1573-1561
    Keywords: Kairomone ; β-phellandrene ; ipsdienol ; monoterpenes ; Ips pini ; Coleoptera ; Scolytidae ; predators ; competition ; primary attraction ; dose response
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The responses ofIps pini (Scolytidae) to multiple-funnel traps baited with the pheromone, ipsdienol, and various monoterpenes were determined in stands of lodgepole pine in southern and central British Columbia.Ips pini was attracted to both ipsdienol and β-phellandrene, demonstrating that β-phellandrene is a kairomone for this species.Lasconotus complex (Colydiidae) and aCorticeus sp. (Tenebrionidae) were attracted to both ipsdienol and β-phellandrene. TheCorticeus sp. exhibited a synergistic response to the combination of ipsdienol and β-phellandrene; the responses of the other two species to the combination were additive. The predators,Thanasimus undatulus, Enoclerus sphegeus, andE. lecontei (Cleridae), were attracted to ipsdienol-baited traps, whileMonochamus clamator (Cerambycidae) andDendroctonus ponderosae (Scolytidae) were attracted to β-phellandrene. Attraction of all eight species increased with increasing release rates of ipsdienol and/or β-phellandrene.
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  • 100
    ISSN: 1573-1561
    Keywords: Oryzaephilus surinamensis (L.) ; Coleoptera ; Cucujidae ; population density ; culture age ; semiochemicals ; oviposition ; larval volatiles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract After 20 days in a high-density culture containing many larvae, female sawtoothed grain beetles,Oryzaephilus surinamensis (L.), laid half as many eggs in a 24-hr oviposition bioassay as females held for six days in the same culture, or for six or 20 days in a low-density culture. Oviposition by females held for six days in a high-density culture was reduced to a similar extent when they were exposed in the oviposition bioassay to an oat flake treated with an extract of Porapak Q-captured larval volatiles (equivalent to 5000 larval hours). A retained suppression of oviposition rate after prolonged exposure to larvae or an induced reduction caused by short-term exposure to larval volatiles both could be of adaptive advantage in reducing the risk of oviposition in an already densely populated habitat.
    Type of Medium: Electronic Resource
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