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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    OR spectrum 16 (1994), S. 47-52 
    ISSN: 1436-6304
    Schlagwort(e): Vector optimization ; approximately efficient solutions ; stability ; Vektoroptimierung ; Näherungslösungen ; Stabilität
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Wir führen ein Konzept für Näherungslösungen in der Vektoroptimierung ein und vergleichen dieses mit einem neuen Konzept aus [8]. Weiterhin untersuchen wir Beziehungen zwischen der Menge der Näherungslösungen eines Vektoroptimierungsproblems und den Näherungslösungen eines entsprechenden parametrischen Ersatzproblems. Schließlich beweisen wir Stabilitätseigenschaften des skalaren Ersatzproblems.
    Notizen: Abstract We introduce a concept for approximately efficient solutions in vector optimization and compare it with another recent concept given in [8]. Further, we study relations between the set of approximately efficient solutions of a vector optimization problem and the approximate solutions of a corresponding parametric surrogate optimization problem. Finally, we prove stability properties for the scalar surrogate problem.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Entomologia experimentalis et applicata 71 (1994), S. 185-192 
    ISSN: 1570-7458
    Schlagwort(e): Lepidoptera ; Pyralidae ; Indianmeal moth ; semiochemicals ; attraction ; oviposition
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Substrates contaminated by wandering fifth instar larvae ofPlodia interpunctella (Hübner) (Lepidoptera: Pyralidae) elicit oviposition by conspecific female moths, and larval rearing diet enhances oviposition and also induces upwind flight. Two-choice oviposition assays determined that four-day-old gravid femaleP. interpunctella preferred to lay eggs on dishes containing cornmeal-based rearing diet compared to empty dishes. Pieces of cheesecloth contaminated by fifth instar larvae elicited more oviposition than untreated cheesecloth or dishes with food. The combination of larval contamination and food was preferred over food only or larval contamination only in both two- and four-choice experiments. The factor(s) in larval contamination responsible for eliciting oviposition in female moths was extracted in hexane, confirming that organic semiochemicals are responsible for the effect. The oviposition-eliciting activity of larval contamination was retained on cheesecloth for up to 30 days following treatment with larvae, suggesting the active component(s) is stable and of low relative volatility. In two-choice windtunnel bioassays female moths initiated flight only when rearing food was present in one of the treatments, and they displayed the highest landing responses to a combination of larval contamination and food. Earlier work onP. interpunctella and related pyralid species found that larval contamination due to secretions from the mandibular glands acted as both a spacing pheromone for wandering larvae and as a kairomone for host-seeking parasitoid wasps. The present study suggests that the same or a similar secretion acts as an oviposition-eliciting pheromone for conspecific females.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Entomologia experimentalis et applicata 72 (1994), S. 173-180 
    ISSN: 1570-7458
    Schlagwort(e): feeding performance ; diapausing propensity ; genetic correlation ; heritability ; host-range ; insect-plant interactions ; Lepidoptera ; Tortricidae
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Evolutionary constraints on the ability of herbivores to efficiently use a set of phytochemically similar hosts, while maintaining a high performance on phytochemically different hosts, are central in explaining the predominance of host specialization in phytophagous insects. Such feeding trade-offs could be manifested within insect populations as negative genetic correlations in fitness on different host species. We tested the hypothesis that feeding trade-offs were present within a population of the obliquebanded leafroller,Choristoneura rosaceana (Harris). Components of fitness were measured in families originating from an apple orchard that were fed on four host-plant species in the laboratory. Under the conditions of this experiment, all across-host genetic correlations were strongly positive, suggesting that this population comprised true generalists. With the exception of diapausing propensity, the heritability of the fitness components tended to be lower in caterpillars fed on apple leaves than in insects fed other hosts. This suggests a constraint on the selective response of the fitness components in the orchard environment.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Entomologia experimentalis et applicata 72 (1994), S. 25-31 
    ISSN: 1570-7458
    Schlagwort(e): diapause induction ; photoperiod ; temperature ; Phyllonorycter blancardella ; spotted tentiform leafminer ; Lepidoptera ; Gracillariidae
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The role of photoperiod and temperature in the induction of overwintering diapause inPhyllonorycter blancardella (F.) (Lepidoptera: Gracillariidae) was examined in the laboratory and field using leafminers from commercial apple orchards in Ontario, Canada.P. blancardella exhibited a long-day response to photoperiod: long daylengths resulted in uninterrupted development whereas short daylengths induced diapause. The estimated critical photoperiod for diapause induction was L14.25∶D9.75. The larvae of leafminers destined to enter diapause took ca. 3× longer to complete development than the larvae of non-diapausing leafminers. The development prolonging effect of photoperiod decreased with decreasing daylength. Temperature modified the diapause inducing effect of photoperiod. At L14.25∶D9.75, diapause incidence was similar at 15 and 20°C but was lower at 25°C. Photoperiod also altered the normal relationship between development rate and temperature. At L14.25∶D9.75, the duration of larval development of diapausing leafminers was similar at 15, 20 and 25°C. Temperature alone is unlikely to have a role in the induction of diapause because leafminers exposed to natural late summer and fall temperature regimes and L16∶D8 did not enter diapause.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    ISSN: 1570-7458
    Schlagwort(e): Lepidoptera ; Pyralidae ; Ectomyelois ceratoniae ; carob moth ; host-finding ; Phoenix dactylifera ; dates ; gas chromatography-electrophysiology ; mass spectrometry ; wind tunnel ; attraction ; volatiles ; headspace
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Four volatile compounds emitted from fungus-infected date fruit,Phoenix dactylifera L., were identified using coupled gas chromatographic-electroantennographic recordings, coupled gas chromatographic-mass spectrometric analysis, electroantennographic assays of synthetic standards, and wind tunnel bioassays. These compounds were ethyl hexanoate, ethanol, acetaldehyde, and 2-phenylethanol. Wind tunnel bioassays showed that ethyl hexanoate was capable of stimulating upwind flight and landing on the source by mated female carob moths,Ectomyelois ceratoniae (Zeller). Addition of both ethanol and acetaldehyde to ethyl hexanoate resulted in an increase in attraction to a level similar to that found for date fruits. No such effect was noted for additions of 2-phenylethanol at the dosages tested. In this study, it appears that ethyl hexanoate is a dominant olfactory stimulant and attractant for mated female carob moths, and represents a novel compound with regard to previously identified lepidopteran host odor attractants.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Entomologia experimentalis et applicata 70 (1994), S. 295-298 
    ISSN: 1570-7458
    Schlagwort(e): forest tent caterpillar moth ; Malacosoma disstria ; fluctuating asymmetry ; survival ability ; pest management ; Lepidoptera
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Fluctuating asymmetry of the first tarsal segment of the proleg of the forest tent caterpiller mothMalacosoma disstria Hbn. (Lepidoptera: Lasiocampidae) was significantly inversely related to survival ability in the lab. The monitoring of population levels of fluctuating asymmetry could have important implications in pest management of this and other species by providing an indication of the health of a population.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Entomologia experimentalis et applicata 71 (1994), S. 33-39 
    ISSN: 1570-7458
    Schlagwort(e): Helicoverpa zea ; Noctuidae ; Lepidoptera ; Eucelatoria bryani ; Tachinidae ; Diptera ; host-parasitoid relationship ; host regulation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The parasitoidEucelatoria bryani Sabrosky regulates the larval behavior of its hostHelicoverpa zea (Boddie). Parasitized third, fourth and fifth instars burrow into the soil 0.7–3.4 days earlier than unparasitized larvae that normally enter the soil to pupate at the end of the fifth and final larval instar. Parasitized third instars molt once then burrow as fourth instars, one instar earlier than normal. WhenE. bryani pupariated on the soil surface in the field, none survived to the adult stage. However,E. bryani adults emerged from 49.2% of hosts that had burrowed into the soil. By accelerating the timing ofH. zea burrowing behavior and causing host larvae to enter the soil before death,E. bryani ensures its pupariation in an environment with improved protection against natural enemies and lethal temperatures.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Entomologia experimentalis et applicata 71 (1994), S. 271-277 
    ISSN: 1570-7458
    Schlagwort(e): Lepidoptera ; Papilionidae ; Zerynthia ; Aristolochia ; herbivory ; phenology ; nutritional indices
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The main host plants of the butterflyZerynthia rumina L. (Lepidoptera: Papilionidae) in southern Spain occur in different habitats and in general do not grow sympatrically. Therefore, each single local butterfly population uses the particular host available within its range.Aristolochia longa L. is a tuberous perennial herb available only in the spring, whileA. baetica L. is an evergreen perennial vine with indeterminate growth. However, because of the toughness of older leaves, newly hatched larvae feed only on new leaves ofA. baetica, and most of these leaves are produced well before the larvae hatch. In laboratory experiments, caterpillars feeding on either new or matureA. longa leaves grew faster and converted food into biomass more efficiently than those feeding on newA. baetica leaves. These differences are related to variation in nutritional quality among the host plants. Estimates of butterfly abundance were lower in sites whereZ. rumina usesA. baetica, compared with those where the host isA. longa. The potential differential effect of these two food plants on the densities of local butterfly populations relying on them is discussed here.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    ISSN: 1570-7458
    Schlagwort(e): Lepidoptera ; Tortricidae ; Choristoneura fumiferana ; juvenile hormone analog ; fenoxycarb ; postembryonic development
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Journal of insect behavior 7 (1994), S. 605-632 
    ISSN: 1572-8889
    Schlagwort(e): Heliothis ; Lepidoptera ; Noctuidae ; pheromone ; visual feedback
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract MaleHeliothis virescens (F.) (Lepidoptera: Noctuidae) were made to fly into a uniformly white and translucent tube within a large wind tunnel while responding to sex pheromone. Different visual patterns placed within the tube greatly affected the ability of the male moths to maintain upwind progress or remain oriented to the wind while in contact with the plume. Over 89% of males attempting to fly through a blank tube, lacking visual patterns, became disoriented, the males gaining or losing altitude and repeatedly hitting the sides of the tube. Patterns of 20–40 dots placed on the sides of the tube at or slightly above plume level resulted in high levels of sustained upwind flight (47–74%) relative to patterns placed directly below (30–40%), directly above (35%), or slightly below the level of the flight path (26–44%). Optimal upwind progression in pheromone-responding males occurred when image motion could be resolved both transversely (T), orthogonally to the longitudinal axis of the body relative to the horizontal plane of the environment, and longitudinally (L), along the body axis. Even very sparse patterns (single rows of dots) could elicit high levels of sustained upwind flight (53–63%) when positioned within the tube such that the males' movements would create both L and T image motion. However, successful negotiation of the tube was also unexpectedly facilitated by patterns apparently providing no horizontal transverse component for flying males but providing longitudinal flow while centering the moth in the plume through a symmetrical left-right input (4–40%).
    Materialart: Digitale Medien
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  • 11
    ISSN: 1572-8889
    Schlagwort(e): parasitoid ; foraging behavior ; Hymenoptera ; Cotesia ; Lepidoptera ; Pieris ; host location ; solitary ; gregarious ; specialist ; generalist
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract In the present study we apply a comparative approach, in combination with experimentation, to study behavior of two parasitoid species that attack caterpillar hosts with different feeding strategies (gregarious or solitary). In a semifield setup, consisting of clean cabbage plants and plants infested with one of two host species, the foraging behavior of the specialistCotesia rubecula, on obligate parasitoid of solitarily feedingPieris rapae larvae, was compared to that of the generalistCotesia glomerata, a polyphagous parasitoid of several Pieridae species (mainly the gregariously feedingPieris brassicae).Cotesia glomerata displayed equal propensity to search for and parasitize larvae of both host species. AlthoughC. glomerata exhibited a relatively plastic foraging behavior in that it searched differently under different host distribution conditions, its behavior seems more adapted to search for gregariously feeding hosts. Females exhibited a clear “area-restricted” search pattern and were more successful in finding the gregariously feeding caterpillars.Cotesia rubecula showed a higher propensity to search forP. rapae than forP. brassicae, i.e., females left the foraging setup significantly earlier when their natural hostP. rapae was not present.C. rubecula showed a more fixed foraging behavior, which seems adapted to foraging for solitarily feeding host larvae. In a setup with onlyP. rapae larvae, the foraging strategies of the two parasitoid species were quite similar. In a choice situationC. glomerata did not show a preference for one of the host species, whileCotesia rubecula showed a clear preference for its natural host species. The latter was shown by several behavioral parameters such as the number of first landings, allocation of search time, and percentage parasitization.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 12
    Digitale Medien
    Digitale Medien
    Springer
    Journal of insect behavior 7 (1994), S. 885-889 
    ISSN: 1572-8889
    Schlagwort(e): Lepidoptera ; Noctuidae ; Mamestra brassicae ; male scents ; hair-pencils ; courtship
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 13
    Digitale Medien
    Digitale Medien
    Springer
    Journal of dynamics and differential equations 6 (1994), S. 37-51 
    ISSN: 1572-9222
    Schlagwort(e): Celestial mechanics ; relative equilibria ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract A criterion for the linear stability of relative equilibria of the Newtoniann-body problem is found in the case whenn−1 of the masses are small. Several stable periodic orbits of the problem are presented as examples.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 14
    Digitale Medien
    Digitale Medien
    Springer
    Queueing systems 15 (1994), S. 279-288 
    ISSN: 1572-9443
    Schlagwort(e): Sample-path ; point processes ; workload ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik
    Notizen: Abstract In this paper, by exploiting recent results on the pathwise behavior of the workload process in single server, work conserving queues of theG/G/1/∞ type, we show that the workload of multiserver, work conserving queues ofG/G/m/∞ (m〈∞) (andG/G/∞) queues satisfies an o(t) growth condition, provided that the time average of the work brought into the system is less thanm form 〈 ∞ (and finite form=∞).
    Materialart: Digitale Medien
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  • 15
    Digitale Medien
    Digitale Medien
    Springer
    Queueing systems 16 (1994), S. 115-137 
    ISSN: 1572-9443
    Schlagwort(e): Polling systems ; stability ; stochastic continuity ; general arrival process ; functional limit theorems.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik
    Notizen: Abstract The stability of a polling system with exhaustive service and a finite number of users, each with infinite buffers is considered. The arrival process is more general than a Poisson process and the system is not slotted. Stochastic continuity of the stationary distributions, rates of convergence and functional limit theorems for the queue length and waiting time processes have also been proved. The results extend to the gated service discipline.
    Materialart: Digitale Medien
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  • 16
    Digitale Medien
    Digitale Medien
    Springer
    Celestial mechanics and dynamical astronomy 58 (1994), S. 203-213 
    ISSN: 1572-9478
    Schlagwort(e): libration points ; resonances ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The stability of the triangular libration points in the case when the first and the second order resonances appear was investigated. It was proved that the first order resonances do not cause instability. The second order resonances may lead to instability. Domains of the instability in the two-dimensional parameter space were determined.
    Materialart: Digitale Medien
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  • 17
    Digitale Medien
    Digitale Medien
    Springer
    Journal of dynamics and differential equations 6 (1994), S. 639-658 
    ISSN: 1572-9222
    Schlagwort(e): Symmetry ; parabolic equations ; positive solutions ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract Symmetry properties of positive solutions of a Dirichlet problem for a strongly nonlinear parabolic partial differential equation in a symmetric domainD ⊂ R n are considered. It is assumed that the domainD and the equation are invariant with respect to a group {Q} of transformations ofD. In examples {Q} consists of reflections or rotations. The main result of the paper is the theorem which states that any compact inC(D) negatively invariant set which consists of positive functions consists ofQ-symmetric functions. Examples of negatively invariant sets are (in autonomous case) equilibrium points, omega-limit sets, alpha-limit sets, unstable sets of invariant sets, and global attractors. Application of the main theorem to equilibrium points gives the Gidas-Ni-Nirenberg theorem. Applying the theorem to omega-limit sets, we obtain the asymptotical symmetrization property. That means that a bounded solutionu(t) asr→∞ approaches subspace of symmetric functions. One more result concerns properties of eigenfunctions of linearizations of the equations at positive equilibrium points. It is proved that all unstable eigenfunctions are symmetric.
    Materialart: Digitale Medien
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  • 18
    Digitale Medien
    Digitale Medien
    Springer
    Queueing systems 15 (1994), S. 211-238 
    ISSN: 1572-9443
    Schlagwort(e): polling system ; stability ; Markov chain ; stochastic monotonicity ; heavy traffic ; nonpreemptive local priority
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik
    Notizen: Abstract This paper deals with the stability of periodic polling models with a mixture of service policies. Customers arrive according to independent Poisson processes. The service times and the switchover times are independent with general distributions. The necessary and sufficient condition for the stability of such polling systems is established. The proof is based on the stochastic monotonicity of the state process at the polling instants. The stability of only a subset of the queues is also analyzed and, in case of heavy traffic, the order of explosion of the queues is given. The results are valid for a model with set-up times, and also when there is a local priority rule at the queues.
    Materialart: Digitale Medien
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  • 19
    Digitale Medien
    Digitale Medien
    Springer
    Queueing systems 17 (1994), S. 317-345 
    ISSN: 1572-9443
    Schlagwort(e): Single-server queue ; spatially distributed arrival points ; travelling server ; Brownian motion ; embedded Markov chain ; stability ; Tweedie's lemma ; regenerative processes ; stochastic decomposition ; equilibrium equations ; mean queue length
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik
    Notizen: Abstract Consider a queueing system where customers arrive at a circle according to a homogeneous Poisson process. After choosing their positions on the circle, according to a uniform distribution, they wait for a single server who travels on the circle. The server's movement is modelled by a Brownian motion with drift. Whenever the server encounters a customer, he stops and serves this customer. The service times are independent, but arbitrarily distributed. The model generalizes the continuous cyclic polling system (the diffusion coefficient of the Brownian motion is zero in this case) and can be interpreted as a continuous version of a Markov polling system. Using Tweedie's lemma for positive recurrence of Markov chains with general state space, we show that the system is stable if and only if the traffic intensity is less than one. Moreover, we derive a stochastic decomposition result which leads to equilibrium equations for the stationary configuration of customers on the circle. Steady-state performance characteristics are determined, in particular the expected number of customers in the system as seen by a travelling server and at an arbitrary point in time.
    Materialart: Digitale Medien
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  • 20
    Digitale Medien
    Digitale Medien
    Springer
    Celestial mechanics and dynamical astronomy 59 (1994), S. 345-374 
    ISSN: 1572-9478
    Schlagwort(e): Lagrangian points ; stability ; oblate primary
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The non-linear stability of the libration pointL 4 in the restricted problem has been studied when there are perturbations in the potentials between the bodies. It is seen that the pointL 4 is stable for all mass ratios in the range of linear stability except for three mass ratios depending upon the perturbing functions. The theory is applied to the following four cases: (i) There are no perturbations in the potentials (classical problem). (ii) Only the bigger primary is an oblate spheroid whose axis of symmetry is perpendicular to the plane of relative motion (circular) of the primaries. (iii) Both the primaries are oblate spheroids whose axes of symmetry are perpendicular to the plane of relative motion (circular) of the primaries. (iv) The primaries are spherical in shape and the bigger is a source of radiation.
    Materialart: Digitale Medien
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  • 21
    Digitale Medien
    Digitale Medien
    Springer
    Journal of dynamics and differential equations 6 (1994), S. 447-486 
    ISSN: 1572-9222
    Schlagwort(e): Free boundary problems ; gasless combustion ; stability ; Hopf bifurcation ; 35R35 ; 35B40 ; 80A25
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract In this paper, we analyze a simple free boundary model associated with solid combustion and some phase transition processes. There is strong evidence that this “one-phase” model captures all major features of dynamical behavior of more realistic (and complicated) combustion and phase transition models. The principal results concern the dynamical behavior of the model as a bifurcation parameter (which is related to the activation energy in the case of combustion) varies. We prove that the basic uniform front propagation is asymptotically stable against perturbations for the bifurcation parameter above the instability threshold and that a Hopf bifurcation takes place at the threshold value. Results of numerical simulations are presented which confirm that both supercritical and subcritical Hofp bifurcation may occur for physically reasonable nonlinear kinetic functions.
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  • 22
    Digitale Medien
    Digitale Medien
    Springer
    Journal of dynamics and differential equations 6 (1994), S. 325-334 
    ISSN: 1572-9222
    Schlagwort(e): Nonlinear Schrödinger equations ; anisotropic standing waves ; stability ; concentration compactness principle ; Davey-Stewartson system ; 35Q35 ; 35B35
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract We study the stability of standing waves for a nonlinear Schrödinger equation, which derives from the generalized Davey-Stewartson system in the elliptic-elliptic case. We prove the existence of stable standing waves under certain conditions.
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  • 23
    Digitale Medien
    Digitale Medien
    Springer
    Journal of dynamics and differential equations 6 (1994), S. 631-637 
    ISSN: 1572-9222
    Schlagwort(e): stability ; fixed point index ; periodic solutions
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract In this paper, we prove that a stable isolated fixed point of an orientation preserving local homeomorphism onR 2 has fixed point index 1. We also give a number of applications to differential equations. In particular, we deduce that a number of existence methods for producing periodic solutions of differential equations in the plane always produce unstable solutions.
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  • 24
    ISSN: 1572-8889
    Schlagwort(e): Tanacetum vulgare ; Tansy ; Lobesia botrana ; European grapevine moth ; Asteracea ; Lepidoptera ; Tortricidae ; oviposition ; behavior ; nonhost plant ; semiochemicals ; plant odor ; olfaction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Females ofLobesia botrana Den. et Schiff. (Lepidoptera Tortricidae) are attracted in natural conditions by volatiles released by a nonhost plant: tansy (Tanacetum vulgare L.; Asteracea). We have shown that both tansy flowers and their odor inhibit oviposition behavior and mating behavior and reduce adult longevity. The mean number of eggs laid per female isolated with tansy flowers was reduced by up to 50% every 2 days during the 6 days of exposure. This reduction was maintained after the tansy was removed. In the presence of tansy essential oil, the egg-laying reduction ranged from about 30 to 80% according to the odor concentration. The number of spermatophores found in females isolated with tansy flowers was also reduced twofold compared to the control treatment, indicating that the presence of tansy reduced mating activity. This mating activity is strongly reduced, by two-thirds, when adults face the highest dose of essential oil compared to controls. The number of eggs laid by the controls cannot be explained by the number of spermatophores. Therefore, the reduction in oviposition has been attributed to the presence of tansy flowers or to the tansy odor. Tansy flowers and tansy odor increased male mortality during the exposure (10% in the control, 50% in the tansy treatment, and up to 98% in the odor treatment). The highest rates of male mortality occurred during the 4- to 6-day period of exposure to flowers or odor. Repellence resulting in sustained locomotor activity is a possible cause of such a mortality. Female mortality was increased only in response to the highest dose of odor. This increase might be due to egg retention, and not directly to a plant effect. We discuss the effects of tansy flower odor on different patterns relative to the reproductive behavior ofL. botrana and, especially, on oviposition behavior in the ecological context of plant selection and polyphagy.
    Materialart: Digitale Medien
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  • 25
    Digitale Medien
    Digitale Medien
    Springer
    Celestial mechanics and dynamical astronomy 60 (1994), S. 307-315 
    ISSN: 1572-9478
    Schlagwort(e): Asteroid ; libration ; resonance ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract It is known that an abridged case of the averaged planar general three-body problem, at first-order resonance, is analytically integrated, using an expansion of the disturbing function linear in the eccentricities. There exist different methods with the help of which the integration can be performed. For the first time Sessin and Ferraz-Mello in the years 1981–88 (Sessin, 1981, 1983; Ferraz-Mello and Sessin, 1984; Ferraz-Mello, 1987, 1988) did an analytic integration for the restricted elliptic three-body problem, in terms of the variablesK andH (K=ΣD j e j cos (ψ1−π j ),H=ΣD j e j sin (ψ1−π j ),D j = const, wheree j and π j are, respectively, the eccentricity and the longitude of the periapsis of thei-th planet, ψ1 is the Delaunay's anomaly), which is inconvenient for the analytical investigation of the evolution of the major semi-axesa j , the eccentricitiese j and the resonance phases ϕ j =ψ1−π j . Later, a different method for the analytical integration of the general three-body problem, in the variablesa j ,e j and ϕ j , was considered by the author (Shinkin, 1993). A disadvantage of both methods is the fact that they use non-canonical changes of variables. But there exists a third very beautiful canonical method of analytical integration of the general planetary problem, which is briefly considered in the present paper and allows us to describe the bifurcations of separatrices (i.e. appearance, disappearance, splitting and confluence of separatrices) separating the domains of libration and circulation of the resonance phase on the phase plane in the averaged planar general three-body problem at first-order resonance. The bifurcation parameter is analytically found and plays an important role in a qualitative description of all kinds of motion in the examined problem.
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  • 26
    Digitale Medien
    Digitale Medien
    Springer
    Acta applicandae mathematicae 37 (1994), S. 129-136 
    ISSN: 1572-9036
    Schlagwort(e): 35B35 ; 35Q30 ; 76N10 ; stability ; Navier-Stokes equations ; compressible fluids
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract We prove that the uniform stability at permanently acting disturbances of a given solution of the Navier-Stokes equations for viscous compressible isothermic fluid is a consequence of the uniform exponential stability of the zero solution of so-called linearized equations.
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  • 27
    Digitale Medien
    Digitale Medien
    Springer
    Celestial mechanics and dynamical astronomy 60 (1994), S. 249-271 
    ISSN: 1572-9478
    Schlagwort(e): Chaos ; periodic orbits ; stability ; asymptotic curves ; homoclinic points ; heteroclinic points
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract We study the structure of chaos in a simple Hamiltonian system that does no have an escape energy. This system has 5 main periodic orbits that are represented on the surface of section $$(y,\dot y)$$ by the points (1)O(0,0), (2)C 1,C 2(±y c, 0), (3)B 1,B 2(O,±1) and (4) the boundary $$y^2 + \dot y^2 = 1$$ . The periodic orbits (1) and (4) have infinite transitions from stability (S) to instability (U) and vice-versa; the transition values of ε are given by simple approximate formulae. At every transitionS →U a set of 4 asymptotic curves is formed atO. For larger ε the size and the oscillations of these curves grow until they destroy the closed invariant curves that surroundO, and they intersect the asymptotic curves of the orbitsC 1,C 2 at infinite heteroclinic points. At every transitionU →S these asymptotic curves are duplicated and they start at two unstable invariant points bifurcating fromO. At the transition itself the asymptotic curves fromO are tangent to each other. The areas of the lobes fromO increase with ε; these lobes increase even afterO becomes stable again. The asymptotic curves of the unstable periodic orbits follow certain rules. Whenever there are heteroclinic points the asymptotic curves of one unstable orbit approach the asymptotic curves of another unstable orbit in a definite way. Finally we study the tangencies and the spirals formed by the asymptotic curves of the orbitsB 1,B 2. We find indications that the number of spiral rotations tends to infinity as ε → ∞. Therefore new tangencies between the asymptotic curves appear for arbitrarily large ε. As a consequence there are infinite new families of stable periodic orbits that appear for arbitrarily large ε.
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  • 28
    Digitale Medien
    Digitale Medien
    Springer
    Celestial mechanics and dynamical astronomy 60 (1994), S. 99-129 
    ISSN: 1572-9478
    Schlagwort(e): Sitnikov motions ; periodic orbits ; stability ; bifurcations
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract In this paper we deal with the circular Sitnikov problem as a subsystem of the three-dimensional circular restricted three-body problem. It has a first analytical part where by using elliptic functions we give the analytical expressions for the solutions of the circular Sitnikov problem and for the period function of its family of periodic orbits. We also analyze the qualitative and quantitative behavior of the period function. In the second numerical part, we study the linear stability of the family of periodic orbits of the Sitnikov problem, and of the families of periodic orbits of the three-dimensional circular restricted three-body problem which bifurcate from them; and we follow these bifurcated families until they end in families of periodic orbits of the planar circular restricted three-body problem. We compare our results with the previous ones of other authors on this problem. Finally, the characteristic curves of some bifurcated families obtained for the mass parameter close to 1/2 are also described.
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  • 29
    Digitale Medien
    Digitale Medien
    Springer
    BIT 34 (1994), S. 62-79 
    ISSN: 1572-9125
    Schlagwort(e): AMS(MOS) 65D30 ; 65B05 ; adaptive ; cubature ; singularity ; extrapolation ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract A new approach to the integration of vertex singularities is described. This approach is based on a non-uniform subdivision of the region of integration and the technique fits well to the subdivision strategy used in many adaptive algorithms. A nice feature with this approach is that it can be used in any dimension and on any region of integration which can be subdivided into subregions of the same form. The strategy can be applied both to vertex singularities and internal point singularities. In the latter case this can be done without an initial subdivision of the region in order to put the singular point in a vertex. It turns out that the technique has excellent numerical stability properties.
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  • 30
    Digitale Medien
    Digitale Medien
    Springer
    Cellular and molecular life sciences 50 (1994), S. 176-181 
    ISSN: 1420-9071
    Schlagwort(e): Cardiac glycoside loss ; Danaus plexippus ; aging ; breakdown of chemical defense ; three trophic level interactions ; automimicry ; Lepidoptera ; Asclepias
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Monarch butterflies (Danaus plexippus) are unpalatable to various vertebrate predators because their larvae sequester bitter and emetic cardiac glycosides (CGs) from milkweed plants (Asclepias spp.). Here we show that the concentration of the defensive CGs decrease as individual butterflies age, regardless of the CGs' initial amounts or specific chemical structures. Consequently, individual monarch butterflies can change from being unpalatable models to palatable mimics during their lifetime. Since monarchs breed continuously over the spring and summer in North America, freshly emerged adult butterflies may serve as noxious models for older individuals which become automimics as they age.
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  • 31
    Digitale Medien
    Digitale Medien
    Springer
    Catalysis letters 28 (1994), S. 25-31 
    ISSN: 1572-879X
    Schlagwort(e): vanadia/alumina ; stability ; NO x selective reduction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Changes of the V2O5/Al3O3 catalyst aged for up to 10 years under real conditions of the selective catalytic reduction of NO x by ammonia (SCR) at the tail gases of the nitric acid plant were characterized by51V NMR spectroscopy, porosimetry, temperature programmed reduction (TPR) and catalytic activity measurements. The catalytic activity and the redox properties of the catalyst were found intact. Only small variations of the ratio of the octahedral and tetrahedral vanadia species were documented by51V NMR on aged catalyst.
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  • 32
    Digitale Medien
    Digitale Medien
    Springer
    OR spectrum 15 (1994), S. 197-203 
    ISSN: 1436-6304
    Schlagwort(e): Inventory ; dynamic programming ; stability ; Lagerhaltung ; Dynamische Optimierung ; Stabilität
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Die Menge der Kostenparameter, für die eine optimale Lösung des dynamischen Losgrößenmodells optimal bleibt wird hier Stabilitätsregion genannt. Die Größe einer solchen Menge kann als Maß der Robustheit einer Lösung angesehen werden. Es ist zu erwarten, daß die Stabilitätsregionen mit wachsendem Zeithorizont schrumpfen und daß sie in diesem Sinne monoton sind. In der vorliegenden Arbeit werden verschiedene hinreichende Bedingungen für diese Monotonie untersucht. Die Bedingungen setzen unter anderem die Existenz von Planungs- und Vorhersage-Horizonten voraus und verallgemeinern so Ergebnisse einer früheren Arbeit, in der Aussagen für gewöhnliche Planungs-Horizonte vorgestellt wurden.
    Notizen: Abstract The set of cost inputs for which an optimal solution of the dynamic lot size model remains valid is called stability region. The size of this region may be viewed as a measure of robustness of a solution. It is an expectation that the stability regions shrink with growing time horizons and that they are monotonous in this sense. In the present paper several sufficient conditions implying monotonicity will be studied. The conditions cover the existence of planning and forecast horizons and generalize the results of a previous paper in wich monotonicity results were presented for the case of ordinary planning horizons.
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  • 33
    Digitale Medien
    Digitale Medien
    Springer
    Meccanica 29 (1994), S. 195-210 
    ISSN: 1572-9648
    Schlagwort(e): Chetaev functional ; pendulum ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Beschreibung / Inhaltsverzeichnis: Sommario Si considera il problema di stabilità di punti di equilibrio di un pendolo fisico con un filo inestensibile appeso ad esso dal punto di vista del teorema di Lagrange sulla stabilità e sulla sua inversione. Difficoltà specifiche relative allo studio di un sistema meccanico di dimensione infinita sono discusse. Si suggerisce un nuovo metodo per lo studio della stabilità rispetto a due metriche. L'influenza di fenomeni di risonanza sul moto del sistema ridotto (linearizzato) è considerata.
    Notizen: Abstract The problem of stability of equilibria of a physical pendulum with a nonstretchable thread attached to it is considered from the standpoint of the Lagrange theorem on stability and its inversion. Specific difficulties which one faces when studying an infinite dimensional mechanical system are discussed. A new approach to the study of stability with respect to two metrics is suggested. The influence of resonant phenomena on the motion of the shortened (linearized) system is considered.
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  • 34
    Digitale Medien
    Digitale Medien
    Springer
    Chemoecology 5-6 (1994), S. 75-77 
    ISSN: 1423-0445
    Schlagwort(e): larval host plants ; distribution ; Lepidoptera ; Noctuidae ; Othreis fullonia
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The adult fruit piercing moth,Othreis fullonia, a native of the indo-Malaysian region, causes severe damage to fruits grown throughout the tropical and subtropical belt from Africa through Asia and Australia to the Pacific Islands. Plants of the family Menispermaceae and the genusErythrina (Fabaceae) serve as larval hosts but the adult moths prefer Menispermaceae plants for oviposition. In Africa, Asia and Australia, the moth does not lay eggs onErythrina since members of the Menispermaceae are abundant. However in the insular Pacific region, where most islands have few or no species of Menispermaceae, the introduced fruit piercing moth utilizesErythrina as an alternate larval host, and either depletes, endangers or causes the possible extinction of Menispermaceae.
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  • 35
    ISSN: 1423-0445
    Schlagwort(e): oviposition ; stimulants ; deterrents ; glucosinolates ; Lepidoptera ; Pieridae ; Pieris rapae ; Pieris napi oleracea ; Alliaria petiolata
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Differential acceptance of garlic mustard,Alliaria petiolata byPieris rapae L. andP. napi oleracea is explained by their differential sensitivities to oviposition stimulants and deterrents in the plant. Fractions containing the stimulants and deterrents were isolated by solvent partitioning between water and n-butanol and by open-column chromatography followed by HPLC.P. napi oleracea showed no preference when offered a choice ofA. petiolata or cabbage, but was strongly stimulated to oviposit by post-butanol water extracts ofA. petiolata. The most abundant glucosinolate in this extract was identified as sinigrin, which could explain the high degree of stimulatory activity.P. rapae preferred cabbage plants overA. petiolata, and the relatively low stimulatory activity was also associated with the glucosinolate-containing aqueous extract. However, this species was strongly stimulated by a fraction that contained small amounts of glucotropaeolin along with unknown compounds. Deterrents to both species were found in the butanol extract fromA. petiolata, andP. napi oleracea was more sensitive thanP. rapae to these deterrents. Some HPLC fractions from the BuOH extract were strongly deterrent toP. napi oleracea, but were inactive toP. rapae. The ecological significance of these behavioral differences between the twoPieris species is discussed.
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  • 36
    Digitale Medien
    Digitale Medien
    Springer
    Chemoecology 5-6 (1994), S. 127-138 
    ISSN: 1423-0445
    Schlagwort(e): sequestration ; defence substances ; toxic substances ; pheromones ; host selection ; aristolochic acids ; pyrrolizidine alkaloids ; grayanotoxins ; cyanoglycosides ; Lepidoptera
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary A number of aposematic butterfly and moth species sequester toxic substances from their host plants. Some of these insects can detect the toxic compounds during food assessment. Some pipevine swallowtails use aristolochic acids among the host finding cues during oviposition and larval feeding and accumulate the toxins in the body tissues throughout all life stages. Likewise, a danaine butterfly,Idea leuconoe, which sequesters high concentrations of pyrrolizidine alkaloids in the body, lays eggs in response to the specific alkaloid components contained in the apocynad host. Insect species sharing the same poisonous host plants may differ in the degree of sequestration of toxins. Two closely ralated aposematic geometrid moth species,Arichanna gaschkevitchii andA. melanaria, sequester a series of highly toxic diterpenoids (grayanotoxins) in different degrees, while a cryptic geometrid species,Biston robstus, does not sequester the toxins, illustrating the diversity in adaptation mechanisms even within the same subfamily. By contrast, a number of lepidopteran species store the same compounds though feeding upon taxonomically diverse plant species. A bitter cyanoglycoside, sarmentosin, was characterised from several moth species in the Geometridae, Zygaenidae and Yponomeutidae, and from the apollo butterflies,Parnassius spp. (Papilionidae), although each species feeds on different groups of plants. Interspecific similarities and differences in life history and ecology are discussed in relation to variable characteristics of sequestration of plant compounds among these lepidopteran insects.
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  • 37
    Digitale Medien
    Digitale Medien
    Springer
    Chemoecology 5-6 (1994), S. 101-117 
    ISSN: 1423-0445
    Schlagwort(e): cardenolides ; cardiac glycosides ; chemical defence induction ; latex ; parasitism ; predation ; sequestration ; Insecta ; Diptera ; Tachinidae ; Lepidoptera ; Nymphalidae ; Danainae ; Danaus plexippus ; Asclepiadaceae
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The contribution of Miriam Rothschild to the “monarch cardenolide story” is reviewed in the light of the 1914 challenge by the evolutionary biologist, E.B. Poulton for North American chemists to explain the chemical basis of unpalatability in monarch butterflies and their milkweed host plants. This challenge had lain unaccepted for nearly 50 years until Miriam Rothschild took up the gauntlet and showed with the help of many able colleagues that monarchs are aposematically coloured because they sequester toxic cardenolides from milkweed host plants for use as a defence against predators. By virtue of Dr Rothschild's inspiration and industry, and subsequently that of Lincoln Brower and his colleagues, this tritrophic interaction has become a familiar paradigm for the evolution of chemical defences and warning colouration. We now know that the cardenolide contents of different milkweeds vary quantitatively, qualitatively and spatially, both within and among species and we are starting to appreciate the implications of such variation. However, as Dr Rothschild has pointed out in her publications, cardenolides have sometimes blinded us to reality and it is curious how little evidence there is for a defensive function to cardenolides in plants — especially against adapted specialists such as the monarch. Thus the review will conclude with a discussion of the significance of temporal variation and induction of cardenolide production in plants, the “lethal plant defence paradox” and an emphasis on the dynamics of the cardenolide-mediated interaction between milkweeds and monarch larvae.
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  • 38
    Digitale Medien
    Digitale Medien
    Springer
    Chemoecology 5-6 (1994), S. 139-146 
    ISSN: 1423-0445
    Schlagwort(e): biochemistry of plants ; sequestration by insects ; transformation by insects ; pyrrolizidine alkaloids ; alkaloidN-oxides ; Asteraceae ; Senecio ; Lepidoptera ; Arctiidae ; Tyria ; Creatonotos
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Among alkaloids the pyrrolizidine alkaloids (PAs) play a unique role in the interactions between plants and adapted insects. InSenecio spp. (Asteraceae) PAs are synthesized in the roots as alkaloidN-oxides which are specifically translocated into shootsvia the phloem-path and channeled to the preferred sites of storage (e.g. inflorescences) where they are stored in the cell vacuoles. In differentSenecio spp. senecionineN-oxide is produced as the common product of biosynthesis, which subsequentlyvia a number of simple but specific reactions is transformed into typical speciesspecific PA-patterns. Insects from diverse taxa sequester PAs for their own defense. Lepidopterans (e.g. arctiids such asTyria jacobaeae andCreatonotos transiens) may hydrolyze plant acquired ester-PAs and convert the resulting necine base into insect-specific PAs by esterification with an acid of their own metabolism. Adapted arctiids and the grasshopperZonocerus take up PAs in the state of the tertiary amine.N-Oxides are reduced in the guts prior to uptake. In the bodies the tertiary PAs are rapidlyN-oxidized by a specific mixed-function oxigenase and are maintained in theN-oxide state. The importance of the reversible interconversion of the nontoxicN-oxide (pro-toxine) into the toxic tertiary alkaloid is discussed as the specific feature of PAs in plant-insect interactions.
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  • 39
    Digitale Medien
    Digitale Medien
    Springer
    Chemoecology 5-6 (1994), S. 167-171 
    ISSN: 1423-0445
    Schlagwort(e): inhibition ; indigestibility ; defence ; alkaloid ; glycosidases ; Lepidoptera
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Glycosidase inhibitors are widespread in plants and can be sequestered by Lepidoptera, for which they can presumably serve as defences by making the insects indigestible to a range of potential predators. As a result of this study of eight British species of moth and butterfly it was found that glycosidase inhibitors in the insects could then be detected in the larval food plants which were not previously known to contain them; however, some were only detectable in the plants after concentration. In some cases the inhibition of specific glycosidases by Lepidoptera was detected even though the insects had not apparently acquired them from their food plants. Inhibition ofβ-N-acetylglucosaminidase was observed in most of the adult Lepidoptera analysed but further work is required to identify the inhibitors, though they are likely to be nitrogen-containing compounds. Weak anti-HIV activity was also observed in the glycosidase-inhibiting fractions ofAcherontia atropos and the plantUrtica dioica.
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  • 40
    Digitale Medien
    Digitale Medien
    Springer
    Chemoecology 5-6 (1994), S. 13-18 
    ISSN: 1423-0445
    Schlagwort(e): predation ; plant-insect interactions ; tritrophic level interactions ; iridoid glycosides ; catalpol ; Lepidoptera ; Nymphalidae ; Junonia coenia ; Hymenoptera ; Formicidae ; Camponotus floridanus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary We investigated the role of the iridoid glycoside, catalpol, as a deterrent to the predator,Camponotus floridanus. Four laboratory colonies of this ant were offered buckeye caterpillars (Junonia coenia: Nymphalidae) raised on diets with and without catalpol. The same colonies were offered sugar-water solutions containing varying concentrations of catalpol, in both no-choice and choice tests. Regardless of diet, buckeye caterpillars appeared to be morphologically protected from predation by the ants, possibly because of their large spines or tough cuticle. However, buckeyes raised on diets with catalpol had high concentrations of catalpol in their hemolymph; extracts of this high-catalpol hemolymph proved to be an effective deterrent to the ants. When starved ants were not given the choice of food items, they were more likely to consume sucrose solutions that contained 5 mg catalpol/ml or 10 mg catalpol/ml than they were to consume solutions with 20 mg catalpol/ml. When they were given a choice of sugar solution or a sugar solution containing catalpol, the ants avoided solutions with catalpol at any of these concentrations. Ant colony responses to catalpol in sucrose solutions varied considerably over time and among colonies.
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  • 41
    Digitale Medien
    Digitale Medien
    Springer
    Chemoecology 5-6 (1994), S. 26-36 
    ISSN: 1423-0445
    Schlagwort(e): chemoreception ; olfaction ; plant volatiles ; electroantennogram ; combined GC-EAG ; evolutionary adaptation ; Lepidoptera ; Papilionidae ; Papilio polyxenes ; Papilio machaon hippocrates ; Papilio troilus ; Apiaceae ; Daucus carota ; Pastinaca sativa ; Asteraceae ; Artemisia dracunculus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Antennae of femalePapilio butterflies perceive many volatile plant constituents with widely differing, constituent-specific sensitivities. We compared the responses of threePapilio species to volatiles from host and non-host plants to assess species-specificity and the degree of evolutionary conservatism in olfactory responses. Since previous studies had demonstrated that the polar constituents in odor fromDaucus carota stimulate oviposition behavior inPapilio polyxenes, we collected headspace volatiles fromD. carota, Pastinaca sativa (both Apiaceae) andArtemisia dracunculus (Asteraceae) and separated the polar fraction of these volatiles by gas chromatography. GC-coupled electroantennograms (GC-EAG) were recorded from the speciesPapilio polyxenes, P. machaon hippocrates andP. troilus. In addition, the responses of the three species to five compounds known as generally occurring constituents of plant odor were recorded. The relative sensitivities for these compounds were nearly identical in all threePapilio species. The response spectra to the separated plant volatiles also showed considerable similarities among the species. From the limited set of GC peaks evoking a response in one of the species, 64% (D. carota), 44% (P. sativa) and 29% (A. dracunculus) also evoked a response in both of the other species. The responses of the two closely related Apiaceae feeders (P. polyxenes, P. m. hippocrates) to volatiles fromD. carota were more similar to each other than was either to the response ofP. troilus, which feeds on Lauraceae. However, this was not true for the responses to volatiles fromP. sativa. The least congruence among the three species was found in the responses to volatiles fromA. dracunculus, a non-host for all of them. The differences and similarities found in the response profiles of the threePapilio species are discussed with respect to evolutionary adaptation to host odor versus evolutionary conservatism in adaptation of olfactory receptors.
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  • 42
    Digitale Medien
    Digitale Medien
    Springer
    Journal of nonlinear science 4 (1994), S. 449-470 
    ISSN: 1432-1467
    Schlagwort(e): solitary waves ; stability ; nonlinear dispersive wave equations ; model equations for long waves ; Korteweg-de Vries-type equations ; regularized long-wave equations ; nonlinear Schrödinger equations ; 35B35 ; 35B40 ; 35Q35 ; 35Q51 ; 35Q53 ; 35Q55 ; 35S10 ; 76B15 ; 76B25 ; 76E30 ; 86A05
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Physik
    Notizen: Summary After a review of the existing state of affairs, an improvement is made in the stability theory for solitary-wave solutions of evolution equations of Korteweg-de Vries-type modelling the propagation of small-amplitude long waves. It is shown that the bulk of the solution emerging from initial data that is a small perturbation of an exact solitary wave travels at a speed close to that of the unperturbed solitary wave. This not unexpected result lends credibility to the presumption that the solution emanating from a perturbed solitary wave consists mainly of a nearby solitary wave. The result makes use of the existing stability theory together with certain small refinements, coupled with a new expression for the speed of propagation of the disturbance. The idea behind our result is also shown to be effective in the context of one-dimensional regularized long-wave equations and multidimensional nonlinear Schrödinger equations.
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  • 43
    ISSN: 1572-8951
    Schlagwort(e): Diazafluorenone ; Schiff-base amphiphiles ; monolayer ; bilayer ; membrane ; stability ; electrochemical oscillations ; chemical sensor
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract A new kind of diazafluorenone Schiff base amphiphile has been synthesized from 1,10-phenanthroline. The superior self-assembling properties of the amphiphiles are advantageous for forming surface monolayer and bilayer membranes (BLMs). BLMs formed with these amphiphiles possess very good stability and electrochemical oscillations. The possibility is suggested of developing a new type of chemical sensor with the ability to distinguish various metal ions from the patterns of electrochemical oscillations.
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  • 44
    Digitale Medien
    Digitale Medien
    Springer
    Acta applicandae mathematicae 34 (1994), S. 71-81 
    ISSN: 1572-9036
    Schlagwort(e): 60F55 ; 60G10 ; 60K15 ; Coupling ; marked-point processes ; regeneration ; stationarity ; stability ; maximal coupling
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract Criteria for semi-, wide-sense-, traditional regeneration and a coupling construction of stochastic processes with embedded point processes are presented.
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  • 45
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical ecology 20 (1994), S. 231-238 
    ISSN: 1573-1561
    Schlagwort(e): Trichoplusia ni ; Lepidoptera ; Noctuidae ; sex pheromone ; behavior ; evolution ; sexual selection
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Male cabbage looper moths,Trichoplusia ni, from two colonies in which all females express an abnormal sex pheromone production phenotype were evaluated in a laboratory wind tunnel for upwind flight responses to the normal and abnormal sex pheromones. The abnormal sex pheromone blend consisted of 20 times as much (Z)-9-tetradecenyl acetate and 30-fold less (Z)-5-dodecenyl acetate compared to the normal pheromone blend. Initially, these males exhibited poor behavioral responses to the abnormal sex pheromone and maximum responses to the normal pheromone blend, indicating that there was no linkage between signal production and response. After 49 generations of laboratory rearing, males from the mutant colonies maintained good responses to the normal pheromone and increased their behavioral response to the abnormal sex pheromone to the same levels as for the normal pheromone. Over the same period, normal males maintained their preference for the normal pheromone. These results indicated that evolution had occurred in mutant colonies in favor of greater male responsiveness to the abnormal sex pheromone, resulting in the broadening of the response spectrum to pheromone blend ratios. This evolution presumably resulted from a mating advantage to those males that did not discriminate against mutant-type females in the mutant colonies.
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  • 46
    ISSN: 1573-1561
    Schlagwort(e): Pieris rapae ; Pieris napi oleracea ; Lepidoptera ; Pieridae ; Barbarea vulgaris ; oviposition ; stimulants ; glucosinolates ; glucobarbarin ; glucobrassicin
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract The closely related butterflies,Pieris rapae andP. napi oleracea, readily laid eggs onBarbarea vulgaris in greenhouse cages. When offered a choice between cabbage andB. vulgaris, P. rapae showed no preference, butP. napi oleracea preferredB. vulgaris. Bioassays of extracts ofB. vulgaris foliage revealed the presence of oviposition deterrent(s) in l-butanol extracts as well as stimulants in the postbutanol water extracts. However, the deterrent effect was apparently outweighed by the strong stimulatory effect in the whole plants. The postbutanol water extract was preferred over an equivalent cabbage extract by both species, but more significantly in the case ofP. napi oleracea. The stimulants were isolated by open column chromatography and HPLC, and the activity was associated with three glucosinolates.P. napi oleracea was more sensitive thanP. rapae to the natural concentration of compounds1 and3, whereas both species were strongly stimulated to oviposit by natural concentrations of compound2. Compounds1 and2 were identified as (2R)-glucobarbarin and (2S)-glucobarbarin, respectively, and3 was identified as glucobrassicin, on the basis of their UV, mass, and NMR spectra. When the pure compounds were tested at the same concentrations applied to bean plants, the (2R)-glucobarbarin at 0.2 mg/plant was preferred over a standard cabbage extract by both butterfly species. However, at a dose of 0.02 mg/plant,P. rapae preferred the cabbage extract whereasP. napi oleracea still preferred the (2R)-glucobarbarin. No such difference in response of the two species to the same two concentrations of (2S)-glucobarbarin was obtained. The results indicate a distinct difference in sensitivity of these butterflies to the epimers of glucobarbarin, and the differences in behavioral responses of the two butterfly species depend to a large extent on the concentration of stimulant present.
    Materialart: Digitale Medien
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  • 47
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical ecology 20 (1994), S. 1039-1051 
    ISSN: 1573-1561
    Schlagwort(e): Pieris rapae ; Pieris napi oleracea ; Lepidoptera ; Pieridae ; oviposition ; deterrents ; cardenolides
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Oviposition responses ofPieris rapae andP. napi oleracea to 18 cardenolides were compared under the same conditions. Effects of different concentrations of selected cardenolides were also tested. Most of the compounds were deterrent to oviposition by both insects, but to significantly different degrees.P. rapae were strongly deterred by K-strophanthoside, K-strophanthin-β, cymarin, convallatoxin, oleandrin, erysimoside, erychroside, and gitoxigenin. The most deterrent compounds forP. napi oleracea were erychroside, cymarin, erysimoside, convallatoxin, and K-strophanthoside. Strophanthidin-based glycosides were more deterrent than digitoxigenin-based ones, and the number and type of sugar substitutions can have profound effects on activity. Both similarities and contrasts were found in responses ofP. rapae andP. napi oleracea to these cardenolides. Cymarin was equally deterrent to bothPieris species at all concentrations tested. However, when compared withP. rapae, P. napi oleracea was less sensitive to most of the cardenolides.P. napi oleracea was insensitive to K-strophanthin-β and oleandrin at 0.5 × 10−4 M, which were highly deterrent toP. rapae.
    Materialart: Digitale Medien
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  • 48
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical ecology 20 (1994), S. 1063-1073 
    ISSN: 1573-1561
    Schlagwort(e): Oxime ether ; NMR data ; pheromone mimics ; ESG studies ; structure-response relationships ; turnip moth ; Agrotis segetum Schiff. ; Lepidoptera ; Noctuidae
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Oxime ether analogs of sex pheromone components of the turnip moth (Agrotis segetum Schiff.) were synthesized by the acidolytic opening of cyclic enol ethers withO-alkyl hydroxylamine hydrochlorides. The compounds varying in chain lengths and in the position of the C=N double bond were studied by electrophysiological single sensillum recordings (electrosen-sillography: ESG). The ESG data indicate in general reduced receptor interaction of all analogs investigated in comparison with natural pheromone components of the turnip moth. The data also show that the grade of decrease of receptor interaction depends on specific structural changes within the molecule. The results demonstrate high complementary pheromone-receptor relationships, predominantly depending on the position of the unsaturated group in the chain, whereas analogs with other structural changes are still recognized as a pheromone-like compound by the receptor.
    Materialart: Digitale Medien
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  • 49
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical ecology 20 (1994), S. 1825-1841 
    ISSN: 1573-1561
    Schlagwort(e): Epiphyas postvittana ; Lepidoptera ; Tortricidae ; electroantennogram ; pheromone ; dispenser ; apple ; mating ; disruption ; atmospheric concentration
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract The absorption and release of the pheromone ofEpiphyas postvititana (Lepidoptera: Tortricidae),E 11–14: OAc andE,E 9, 11–14: OAc (95:5) by apple leaves was studied using electroantennograms (EAG) and sticky traps baited with pheromone-treated leaves. Leaves exposed to an airstream containing pheromone reached a constant level of pheromone release within 3 min. Release occurred over a period greater than 24 hr, following removal of leaves from the pheromone-saturated environment. Pheromone-treated leaves were effective as lures in sticky traps for at least three nights, although the average catch per night decrease logarithmically with time. In the field, pheromone was detected by EAG on leaves harvested from up to 25 cm away from a central point source of pheromone. The shape of a surface representing equal pheromone re-release from leaves around a central point source was defined by interpolation from a three-dimensional transect. Leaves harvested from 5 cm under the dispensers showed the highest pheromone release rate. Leaves downwind of the dispensers also had higher release of pheromone. In a treated orchard, significantly higher EAG measurements were recorded in the rows of trees that contained dispensers, compared to grass interrows or untreated trees. The implications of foliar pheromone adsorption and release on atmospheric concentrations and insect behavior require further investigation.
    Materialart: Digitale Medien
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  • 50
    ISSN: 1573-1561
    Schlagwort(e): Lepidoptera ; Tortricidae ; Acleris variana ; sex pheromone ; (E)-11,13-tetradecadienal
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract (E)-11,13-Tetradecadienal (E11,13–14:Ald) is the major sex pheromone component of the eastern blackheaded budworm (EBB),Acleris variana (Fern.). The compound was identified in female pheromone gland extracts by coupled gas chromatographic-electroantennographic detection (GC-EAD), coupled GC-mass spectrometry in selected ion monitoring mode, and retention index calculations of candidate pheromone components.E11,13–14:Ald alone as trap bait was very attractive to male EBB. Addition of the corresponding diene alcohol or acetate or both did not enhance attraction. (Z)-11,13-Tetradecadienal in binary combination with (E)-11,13–14:Ald neither enhanced nor reduced trap catches. Increasing the amounts of pheromone from 0.01 to 10 µg increased trap catches, but increase of pheromone quantity above 100 µg proportionately reduced attraction. Stabilization of slowly polymerizingE11,13–14:Ald and development of a sustained, adequate release rate is required for pheromone-based monitoring of EBB populations.
    Materialart: Digitale Medien
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  • 51
    ISSN: 1573-5028
    Schlagwort(e): alcohol dehydrogenase ; cDNA ; enzyme ; tepary ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The zinc-binding long-chain alcohol dehydrogenases from plants and animals exhibit a considerable level of amino acid sequence conservation. While the functional importance of many of the conserved residues is known, the role of others has not yet been determined. We have identified a naturally occurring Adh-1 allele in the legume Phaseolus acutifolius with several unusual characteristics. Individuals homozygous for this allele, Adh-1CN, possess a single isozyme starch gel electrophoretic pattern suggestive of a null allele, and exhibit ADH enzyme activity levels ca. 60% lower than the standard wild-type Adh-1F line. Interestingly, analysis of Adh-1CN homozygotes on an alternative gel system indicates that Adh-1CN does encode a polypeptide capable of forming functional homo- and heterodimers. However, the levels of ADH activity displayed by these isozymes are far lower than those observed for the corresponding wild type ADH-1F isozymes. Dialysis experiments indicate that isozymes containing the ADH-1CN polypeptide are inactivated by slightly acidic conditions, which may explain the apparent null phenotype on starch gels. Elevated temperatures cause a similar loss of enzyme activity. The deduced amino acid sequences of ADH-1CN and ADH-1F were obtained from their corresponding cDNA clones, and the only significant difference detected between the two is a single amino acid replacement substitution. Residue 144 is occupied by phenylalanine in the ADH-1F polypeptide, whereas serine occupies this position in the ADH-1CN polypeptide. The proximity of residue 144 to the catalytic zinc in the substrate-binding pocket, coupled with the fact that it is integral to a defined hydrophobic core of the ADH polypeptide, may explain the observed disruptive effect that the serine substitution has on both the activity and stability of the ADH-1CN polypeptide. It also provides an explanation for the maintenance of phenylalanine or the structurally similar tyrosine at this residue in Zn-binding long-chain ADHs.
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  • 52
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 32 (1994), S. 395-426 
    ISSN: 1432-1416
    Schlagwort(e): Uniform persistence ; stability ; Lyapunov functional ; level-crossing
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract Dynamical characteristics of an integrodifferential system modelling two species competition with hereditary effects are investigated; in particular we derive sufficient conditions for the persistence of the species, existence of an attracting periodic solution and ‘level-crossings’ of solutions about the periodic solution.
    Materialart: Digitale Medien
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  • 53
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 32 (1994), S. 515-520 
    ISSN: 1432-1416
    Schlagwort(e): Gametophytic incompatibility ; model ; equilibrium ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract The deterministic dynamics of the classical single-locus multiple-allele model of gametophytic incompatibility is analyzed with the intention to prove the conjecture that the symmetric state (uniform distribution of genotypes) is the only polymorphic equilibrium and that this equilibrium is globally asymptotically stable in the interior of the frequency simplex. It is shown that the minimum allelic frequency increases strictly over the generations as long as a uniform allelic distribution is not realized. Hence, the minimum allelic frequency is a Ljapunov function for the invariant set of genotypic frequencies characterized by a uniform allelic distribution. Within this set, the uniform genotypic distribution is approached in an exponential fashion, which proves the assertion. An evolutionary optimization rule associated with the global convergence to the symmetric state is implied by the fact that at this state the overall amount of pollen elimination resulting from incompatible crosses is minimized.
    Materialart: Digitale Medien
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  • 54
    ISSN: 1573-9171
    Schlagwort(e): dysprosium(III) ; aminobenzoic acids ; complex ; structure ; stability ; paramagnetic birefringence
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Steric structures of dysprosium(III) aminobenzoate complexes with the 1∶1 and 1∶2 molar ratio in aqueous solutions were determined on the basis of pH-metric and paramagnetic birefringence data. An increase in conjugation observed for the series of the acids,viz., benzoic,meta-, ortho-, andpara-aminobenzoic acids, results in the increased stability of the complexes with the 1∶1 and 1∶2 composition. In the case ofpara-aminobenzoic acid, the polyhedra [DyL(H2O)6]2+ and [DyL2(H2O)4]+ are cubes with the ligands coordinated to one and two edges, respectively. In the case ofmeta-aminobenzoic acid, the polyhedra [DyL(H2O)6]2+ and [DyL2(H2O)4]+ are a dodecahedron with the ligand coordinated to one edge and a square anti-prism with the ligands coordinated to two edges, respectively. In the case ofortho-aminobenzoic acid, both the 1∶1 and 1∶2 complexes have structures that are intermediate between the structures ofmeta- andpara-aminobenzoic acids.
    Materialart: Digitale Medien
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  • 55
    Digitale Medien
    Digitale Medien
    Springer
    Acta mechanica Sinica 10 (1994), S. 311-325 
    ISSN: 1614-3116
    Schlagwort(e): finite deformation ; rigid-perfect plasticity ; stability ; extremum principles ; plastic limit analysis ; post-yield analysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract The post yield behavior of rigid-perfectly plastic solids at the collapse load is studied based on the finite deformation theory. By using the general duality theory developed by Gao-Strang (1989), a global stability criteria is proposed and a pair of dual extremum principles, expressed in terms of displacements, displacement rates and the Kirchhoff stresses are established for plastic collapse analysis. It is proved that under large deformations, the existence of the plastic limit state at the collapse load depends on the directional derivative of a so-called complementary gap function. The application to the nonlinear plastic collapse theory yields a pair of dual bounding theorems for limit loading factor associated with any transient displacement of the deformed body when the global extremum criteria are satisfied.
    Materialart: Digitale Medien
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  • 56
    Digitale Medien
    Digitale Medien
    Springer
    Numerical algorithms 8 (1994), S. 201-220 
    ISSN: 1572-9265
    Schlagwort(e): Automatic ; adaptive ; cubature ; singularity ; extrapolation ; stability ; 65D30 ; 65-04 ; 65B05
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract We describe an automatic cubature algorithm for functions that have a singularity on the surface of the integration region. The algorithm combines an adaptive subdivision strategy with extrapolation. The extrapolation uses a non-uniform subdivision that can be directly incorporated into the subdivision strategy used for the adaptive algorithm. The algorithm is designed to integrate a vector function over ann-dimensional rectangular region and a FORTRAN implementation is included.
    Materialart: Digitale Medien
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  • 57
    ISSN: 1573-0646
    Schlagwort(e): carzelesin (U-80,244) ; analytical characterization ; parenteral formulation ; stability ; degradation products
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The aim of this study was to design a parenteral dosage form for the investigational cytotoxic drag carzelesin. A stable formulation in PET (Polyethylene glycol 400/absolute ethanol/Tween 80, 6:3:1, v/v/v) was developed. The prototype, containing 0.50 mg carzelesin in 2.0 ml PET formulation, was found to be the optimal formulation in terms of solubility, stability and dosage requirements in phase I clinical trials. Quality control of the formulation showed that the pharmaceutical preparation of carzelesin in PET is not negatively influenced by the manufacturing process. Shelf life studies demonstrated that the formulation is stable for at least 1 year, when stored at −30°C in the dark. In addition, the stability of carzelesin in the PET formulation is discussed as a function of temperature, additives and after dilution in infusion fluids.
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  • 58
    ISSN: 1573-904X
    Schlagwort(e): peptides ; liquid crystals ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 59
    Digitale Medien
    Digitale Medien
    Springer
    Pharmaceutical research 11 (1994), S. 764-771 
    ISSN: 1573-904X
    Schlagwort(e): chimeric antibody ; protein ; stability ; multiple freezing and thawing ; aggregation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Chimeric L6 is a mouse–human monoclonal antibody specific for tumor cell-associated antigens. The factors affecting the physical and chemical stability of chimeric L6 were assessed at elevated temperatures (30–60°C) and by multiple freezing and thawing. Three routes of degradation were observed: chemical degradation to smaller molecular weight species, irreversible aggregation, and formation of a reversible dimer. The specific pathway depended on the stress condition applied and the pH, with maximal overall stability to both thermal stress and multiple freezing/thawing observed at about pH 5.5. Other factors including antibody concentration, buffer concentration, NaCl concentration, and agitation had minimal influence on the stability. Commonly used sugars, polyhydric alcohols, and amino acids effectively prevented freeze/thaw-induced aggregation.
    Materialart: Digitale Medien
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  • 60
    Digitale Medien
    Digitale Medien
    Springer
    Pharmaceutical research 11 (1994), S. 1698-1703 
    ISSN: 1573-904X
    Schlagwort(e): cyclodextrin ; equilibrium model ; nasal delivery ; peptides ; peptidase ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Leucine enkephalin (YGGFL) undergoes rapid degradation in sheep nasal mucosa to yield GGFL which is further degraded to FL. The activity of the nasal mucosal homogenate against YGGFL and GGFL (t1/212 and 7 min) was significantly greater than that observed with a nasal wash fluid (t1/2 40 and 13 min). The effect of cyclodextrins on the rate of degradation of FGG and YGGFL by leucine aminopeptidase (LAP) and of GGF by carboxypeptidase A (CPA) was monitored. Little effect was observed with FGG (with LAP) but the half-life of YGGFL (with LAP) was extended from ~44 min to ~75 min in the presence of a 25-fold excess of β-cyclodextrin. The stability of GGF (with CPA) was also enhanced; an effect was observable with a 5-fold excess of cyclodextrin and the half-life could be extended by 40–75%. An equation is presented which allows the estimation of the concentration of free peptide in the peptide-cyclodextrin solutions.
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  • 61
    Digitale Medien
    Digitale Medien
    Springer
    Pharmaceutical research 11 (1994), S. 206-212 
    ISSN: 1573-904X
    Schlagwort(e): taxol ; mixed micelles ; liposomes ; formulation ; solubility ; stability ; antitumor activity ; acute toxicity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Taxol is a promising antitumor agent with poor water solubility. Intravenous administration of a current taxol formulation in a non-aqueous vehicle containing Cremophor EL may cause allergic reactions and precipitation upon aqueous dilution. In this study a novel approach to formulate taxol in aqueous medium for i.v. delivery is described. The drug is solubilized in bile salt (BS)/phospholipid (PC) mixed micelles. The solubilization potential of the mixed micelles increased as the total lipid concentration and the molar ratio of PC/BS increased. Precipitation of the drug upon dilution was avoided by the spontaneous formation of drug-loaded liposomes from mixed micelles. The formulation can be stored in a freeze-dried form as mixed micelles to achieve optimum stability, and liposomes can be prepared by simple dilution just before administration. As judged by a panel of cultured cell lines, the cytotoxic activity of taxol was retained when formulated as a mixed-micellar solution. Further, for the same solubilization potential, the mixed-micellar vehicle appeared to be less toxic than the standard nonaqueous vehicle of taxol containing Cremorphor EL.
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  • 62
    Digitale Medien
    Digitale Medien
    Springer
    Evolutionary ecology 8 (1994), S. 150-171 
    ISSN: 1573-8477
    Schlagwort(e): bottom-up effects ; food chain ; functional response ; limit cycle ; predator ; prey ; stability ; topdown effects ; trophic structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary This article investigates the mean abundances of trophic levels in simple models of two- and three-level food chains as a function of the rate of input of nutrients. The analysis concentrates on cases in which the equilibrium point with all species present is unstable. In most of the models, the instability arises because the consumer species become satiated when food density is high. In unstable two-level systems, bottom level abundance generally increases with increased nutrient input. The abundance of the second level may decrease with increased input. Changes in the intrinsic rate of increase and carrying capacity of the bottom level can have qualitatively opposite effects on trophic level abundances. Refuges for or immigration of the bottom level usually cause both levels to increase in mean abundance with an increased carrying capacity. A variety of different predator—prey models are discussed briefly and the results suggest that increased nutrient input will often increase the abundance of both levels; however, several circumstances can cause the top level to decrease. In three-level systems, an increased carrying capacity can cause extinction of the top level. Extinction may or may not be conditional on the initial densities of the three levels. These results may help explain the observed lack of correlation between productivity and the number of trophic levels in natural food webs, as well as the lack of very long food chains. The results suggest that patterns of abundances across productivity gradients cannot be used to assess the importance of top-down vs bottom-up effects.
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  • 63
    Digitale Medien
    Digitale Medien
    Springer
    Colloid & polymer science 272 (1994), S. 1166-1173 
    ISSN: 1435-1536
    Schlagwort(e): Gel-emulsions ; ESR spin-probe method ; order parameter ; isotropic hyperfine splitting constant ; correlation time ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract W/O gel-emulsions (high-internal-phase-volume-ratio emulsions) form in water (or brine) /tetraethyleneglycol dodecyl ether/heptane system above the HLB (hydrophile-lipophile balance) temperature of the system. A salt, which largely decreases cloud temperature in a water-nonionic surfactant system, makes the surfactant film rigid and the gel-emulsions hence become very stable. The effect of aded salt on the apparent order parameter “S”, and the isotropic hyperfine splitting constant “a N” in gel-emulsions was determined by the ESR spin probe method using 5-doxyl stearic acid as the spin probe. The apparent order parameter “S”, and the isotropic hyperfine splitting constant “a N” increase with increasing salinity in Na2SO4, CaCl2, and NaCl systems. It is considered that the surfactant molecules are tightly packed in these systems and this tendency is highly related to the stability of gel-emulsions. The salt dehydrates the hydrophilic moiety of surfactant and hence the lateral interactions of surfactant molecular layer at the water-oil interface increases. The observed difference in the apparent order parameter between the ordinary emulsions and the gel-emulsions suggests that most of the surfactant molecules are adsorbed at the oil-water interface (the surface of the water droplet) in gel-emulsions.
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  • 64
    ISSN: 1435-1536
    Schlagwort(e): Microgel ; poly(N-isopropyl-acrylamide) ; surface methylation ; stability ; aggregation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract The stability of thermoreversible microgel particles of poly(N-isopropylacrylamide) having carboxylate surface charge groups has been studied in the presence of electrolyte and non-adsorbing polymer. Methylation of the surface charge groups leads to a decrease in the electrophoretic mobility of the particles and also the interparticle electrostatic repulsive potential, resulting in the material becoming more susceptible to flocculation. The Hamaker constant of the microgel particles increases with the decrease in the hydrodynamic size of the particles following heating. This brings about an increase in the van der Waals attractive energy which results in the particles aggregating in the presence of sufficient electrolyte. Under conditions of flow through membranes, where shearing forces are operative, the flocculation observed following the heating of the dispersions results in the blockage of pores.
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  • 65
    ISSN: 1573-1561
    Schlagwort(e): Lepidoptera ; Noctuidae ; Diachrysia chrysitis ; Diachrysia tutti ; pheromones ; sibling taxa ; electroantennographic responses ; biosynthesis ; cross-attraction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract The noctuid sibling taxaDiachrysia chrysitis s. str. andD. tutti, of yet uncertain taxonomic status, have previously been shown to possess differences in morphology and to be attracted to different mixtures of the two presumed pheromone components (Z)-5-decenyl acetate and (Z)-7-decenyl acetate. TypicalD. tutti males (clearly broken forewing marking) are known to respond to a 2: 100 mixture of the two isomers, whereasD. chrysitis males (unbroken marking) are attracted to a 100: 10 mixture. We investigated female pheromone production and male electroantennographic (EAG) response inDiachrysia families raised in the laboratory from field-collected gravid females. Extracts of individual females from typicalD. tutti andD. chrysitis families were subjected to gas chromatography with simultaneous flame ionization and electroantennographic detection. All females produced mixtures of Z5- and Z7-10:OAc, but femaleD. chrysitis produced predominantly Z5-10:OAc and the antennae of their brothers responded more strongly to the Z5 peak than to the Z7-10:OAc peak, whereas the opposite was true forD. tutti families. The pheromone components were shown to be biosynthesized from hexadecanoic and tetradecanoic acid, respectively by Z11-desaturation followed by chain shortening, reduction, and acetylation. The EAG responses of males trapped with the typicalD. tutti andD. chrysitis blends, as well as with an intermediate blend, were investigated. Males trapped with theD. tutti mixture almost exclusively had a clearly broken wing marking and showed strongest EAG response to Z7-10:OAc. The intermediate blend and theD. chrysitis mixture gave more mixed catches, but with a prevalence of males with an unbroken (or almost unbroken) wing marking and with a higher mean response to Z5-10:OAc. Some males with typicalD. tutti EAG responses were attracted in the field to theD. chrysitis pheromone. In the flight tunnel someD. chrysitis males were attracted also to theD. tutti mixture. This indicates that cross attraction may take place between the two taxa under natural conditions.
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  • 66
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical ecology 20 (1994), S. 171-181 
    ISSN: 1573-1561
    Schlagwort(e): Codling moth ; Cydia pomonella ; Lepidoptera ; Tortricidae ; communication disruption ; mating disruption ; sex pheromone ; (E,E)-8,10-dodecadien-1-ol ; (E,Z)-8,10-dodecadien-1-ol ; (Z,E)-8,10-dodecadien-1-ol ; dodecan-1-ol ; tetradecan-1-ol
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract In a small section of an apple orchard, six traps were placed each in control and test areas and baited with live virgin female codling moths. Gray elastomer septa were used to dispense communication disruptants around the traps. Dyed male codling moths were released in control and test areas, and the numbers of males captured in control and test traps were compared. In 1991, linear regression curves of percent communication disruption versus logarithm of dose were obtained for three compositions: (E,E)-8,10-dodecadien-1-ol, codlemone (1); codlemone + dodecan-1-ol + tetradecan-1-ol (2); and an equilibrium mixture of the four isomers of 8,10-dodecadien-1-ol (30, (61%EE, 14%ZE, 20%EZ, and 5%ZZ). All three regressions gaver 2 values greater than 0.90. At the 95% confidence limits, slopes and intercepts of compositions 1 and 2 were equivalent, and different from that of composition 3, which produced the greatest percentages of disruption at all doses. In 1992, five treatments were compared at a single dose: 1, 3, none (4), (Z,E)-8,10-dodecadien-1-ol (5), (E,Z)-8,10-dodecadien-1-ol (6). Compositions 5 and 6 gave the greatest and similar percentages of disruption and were different from codlemone (1) and 4 (95% confidence), but not from composition 3. Communication disruption produced by composition 3 was greater than (codlemone), which was greater than 4.
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  • 67
    ISSN: 1573-1561
    Schlagwort(e): Lepidoptera ; Tortricidae ; Cydia pomonella ; codling moth ; sex pheromone ; halogenated analogs ; isosteric replacements ; EAG ; single sensillum recording ; field trapping ; structure-activity relationship ; codlemone
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Pest monitoring and control of the codling moth,Cydia pomonella L., have been developed using the main pheromone component of this species, (E,E)-8,10-dodecadienol (codlemone). However, the activity of codlemone is not satisfactory for pest control by mating disruption. Thus, we have synthesized halogenated analogs of codlemone to see if they could be used as new agents for pest control of the codling moth. Their biological activity was measured by electrophysiological techniques. In EAG screening, codlemone was the most active compound. F(10,11)-codlemone [(E,E)-10,11-difluoro-8,10-dodecadienol] and Cl-codlemone [(E,E)-11-chloro-8,10-undecadienol] elicited significant EAG responses, F(10,11)-codlemone triggering responses not significantly different from responses to codlemone. EAG cross-adaptation experiments and single sensillum recordings revealed that these compounds were detected by the same receptor neuron type as codlemone. No competitive inhibition with codlemone was observed from nonactive compounds. In field trapping, F(10,11)-codlemone and Cl-codlemone were more attractive to male codling moths than codlemone itself. Possible explanations of this activity are discussed.
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  • 68
    ISSN: 1573-1561
    Schlagwort(e): Citrus jambhiri ; Trichoplusia ni ; Lepidoptera ; Noctuidae ; bergapten ; furanocoumarins ; phototoxins ; plant-herbivore interactions ; psoralen ; ultraviolet-B radiation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Projected decreases in stratospheric ozone may result in increases in shortwave ultraviolet (UVB) irradiation at the earth's surface. Furanocoumarins, phototoxic compounds found inCitrus jambhiri foliage, increase in concentration when these plants are grown under enhanced UVB. Survivorship schedules ofTrichoplusia ni (Lepidoptera: Noctuidae) caterpillars reared on plants in the presence and absence of enhanced UVB regimes differ significantly; larvae develop more slowly in early life when reared on plants exposed to increased UVB. This same developmental pattern is observed whenT. ni larvae are reared on artificial diets amended with ecologically appropriate amounts of furanocoumarins. Thus, anthropogenically derived changes in stratospheric ozone and concomitant changes in UV light quality at the earth's surface may influence ecological interactions between insects and their host plants by altering secondary metabolism and hence foliage quality for herbivores.
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  • 69
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical ecology 20 (1994), S. 639-650 
    ISSN: 1573-1561
    Schlagwort(e): Soybean ; lipoxygenase ; peroxidase ; polyphenol oxidase ; trypsin inhibitor ; ascorbate oxidase ; oxidative stress ; Lepidoptera ; Noctuidae ; Helicoverpa zea ; corn earworm ; Cerotoma trifurcata ; bean leaf beetle ; Coleoptera ; Chrysomelidae ; Spissistilus festinus ; three-cornered alfalfa hopper ; Homoptera ; Membracidae ; induced resistance ; interspecific competition
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Variation in induced responses in soybean is shown to be dependent, in part, upon herbivore species. Herbivory by the phloem-feeding three-cornered alfalfa hopper caused increases in the activities of several oxidative enzymes including lipoxygenases, peroxidases, ascorbate oxidase, and polyphenol oxidase. Bean leaf beetle defoliation caused increased lipoxygenase activity, but had little effect upon peroxidase, polyphenol oxidase, ascorbate oxidase, or trypsin inhibitor levels in either field or greenhouse studies. In one field experiment, prior herbivory by the bean leaf beetle subsequently reduced the suitability of foliage to the corn earwormHelicoverpa zea. The contribution of these findings to emerging theories of insect-plant interactions is discussed.
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  • 70
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical ecology 20 (1994), S. 745-751 
    ISSN: 1573-1561
    Schlagwort(e): Sex pheromone ; (E)-11-hexadecenal ; (E)-11-hexadecen-1-yl acetate ; Palpita unionalis ; Lepidoptera ; Pyralidae ; Pyrustinae ; Anisodes sp. ; Geometridae ; jasmine moth
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract (E)-11-Hexadecenal and (E)-11-hexadecen-1-yl acetate were found in abdomen tip extracts from females of the jasmine mothPalpita unionalis (Hübn). The identification was based on capillary GC analyses, mass spectrometry, and laboratory and field tests. In laboratory bioassays, both components elicited a low level of upwind flight by males. The two components when tested separately in the field were inactive, but the blend of the two components at a ratio of (3:7) was highly attractive to males. Traps baited with 1 mg of the two-component blend were competitive to traps baited with five virgin females. The addition of Z isomers components reduced male capture.
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  • 71
    ISSN: 1573-1561
    Schlagwort(e): Lepidoptera ; Tortricidae ; Spilonota ocellana ; eye-spotted bud moth ; sex pheromone ; (Z)-8-tetradecenyl acetate and (Z)-8-tetradecenyl alcohol
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Response of male eye-spotted bud moth,Spilonota ocellana (Denis and Schiffermüller), to different ratios of synthetic sex pheromone components, (Z)-8-tetradecenyl acetate (Z8-14:OAc) and (Z)-8-tetradecenyl alcohol (Z8-14:OH), were compared in four North American locations and in one location in The Netherlands. In British Columbia, Nova Scotia, Michigan, and The Netherlands, a 99:1 blend ofZ8-14:OAc andZ8-14:OH captured significantly more maleS. ocellana thanZ8-14:OAc alone or binary blends containing 10–50%Z8-14:OH. In Ontario, where population sizes were low compared to the other four locations, trends in trap catches were similar, and there was no indication that maleS. ocellana responded differently to the tested pheromone blends. A 99:1 blend ofZ8-14:OAc andZ8-14:OH should be most effective in pheromone-based control programs ofS. ocellana in North America and in The Netherlands. Our results confirm earlier studies that a 99:1 blend ofZ8-14:OAc andZ8-14:OH captures significantly more maleS. ocellana thanZ8-14:OAc alone. However, our finding that a 99:1 blend ofZ8-14:OAc andZ8-14:OH is significantly more attractive than binary blends containing 10–50%Z8-14:OH differs from previous findings in Germany and Switzerland.
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  • 72
    ISSN: 1573-1561
    Schlagwort(e): Plutella xylostella ; Lepidoptera ; Plutellidae ; Brassica ; host plant attraction ; EAG ; bioassay ; host plant location ; plant volatiles ; mustard oils ; isothiocyanates
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Olfactory attraction of female diamondback moths (Plutella xylostella) to odors of intact and homogenized host plants, as well as individual compounds characteristic of host plants, were investigated by behavioral and electrophysiological methods. Moths were attracted to odors ofBrassica juncea andB. napus seedlings in a Y-tube bioassay. Solvent fractions of homogenizedB. juncea leaves were attractive to moths whether or not isothiocyanates (IC) were present. Moths were attracted in Y-tube bioassays and to field traps baited with individual ICs. Volatiles fromB. juncea andB. napus elicited an electroantennogram (EAG) response and were attractive in the Y-tube bioassay. Allyl IC was shown to be the attractive component in homogenized plant volatiles but was found to be virtually absent from intact plant volatiles. Gas chromatographic fractionation of intact plant volatiles revealed a terpene-containing fraction to be most attractive to the moths. We were unable to isolate individual attractive compounds from this fraction. Our results suggest that certain elements of this fraction, possibly in combination, are important olfactory cues for host-plant finding by the diamondback moth with mustard oils playing an important and possibly synergistic role, particularly when plants are damaged.
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  • 73
    ISSN: 1573-1561
    Schlagwort(e): Cucurbitaceae ; Cucurbita pepo ; Insecta ; Lepidoptera ; Pyralidae ; Diaphania ; oviposition ; nitidalis ; pickleworm moth ; egg laying ; visitations ; stimulation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Fourteen volatile compounds occurring in leaf trichomes of yellow squash (Cucurbita pepo L. cv. Early Prolific Straightneck) were identified. These compounds accounted for 83.5% of the volatile matrix. Ubiquitous constituents of the epidermis (myristic, palmitic, and stearic acids,n-tricosane, andn-pentacosane) accounted for 73.7%; these compounds were not bioassayed. The volatileso-,m-, andp-xylene, toluene, 2-heptanone, (R)-(+)- and (S)-(−)-limonene, and germacrene D were tested for their influence on attraction and oviposition by the pickleworm moth (Diaphania nitidalis Stoll.). No single compound, except germacrene D, was attractive. (R)-(+)-Limonene and 2-heptanone were weakly repellent. Mixtures of the highly volatile fractions were as attractive as volatiles emanating from whole, intact leaves. Oviposition levels on treated artificial sites corresponded with levels of visitation. Oviposition was significantly stimulated by “whole-leaf” volatiles, and (S)-(−)-limonene caused a slight but significant reduction.
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  • 74
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical ecology 20 (1994), S. 2127-2138 
    ISSN: 1573-1561
    Schlagwort(e): Attacus atlas ; biogenic amines ; chemical defense ; defensive glands of caterpillars ; histamine ; Lepidoptera ; Saturniidae
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract The ability ofAttacus atlas caterpillars to spray a defensive secretion seems to be due to the fine structure of the integumental glands that produce it. The giant gland cells are fixed to stable cuticular rings surrounding the gland openings and tightly closed by cuticular lids. Probably by increasing hemolymph pressure, the lids are blasted off and the secretion spouts out. The fluid contains several aromatics, biogenic amines (e.g., acetylcholine, histamine), glycerol, and trehalose and exhibits tyrosinase activity. Deterrent effects of caterpillar secretion and hemolymph on predatory ants could be shown. Presumably the spraying process serves to apply the secretion to sensitive sites of vertebrate target organisms.
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  • 75
    ISSN: 1573-1561
    Schlagwort(e): Lepidoptera ; Pieridae ; Hymenoptera ; Braconidae ; cabbage ; Brussels sprouts ; behavior ; tritrophic interactions ; green-leaf volatiles ; herbivore-induced synomones ; elicitor ; caterpillar regurgitant ; Brassica oleracea ; Pieris brassicae ; Cotesia glomerata ; parasitoid ; wasp
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Induction of plant defense in response to herbivory includes the emission of synomones that attract the natural enemies of herbivores. We investigated whether mechanical damage to Brussels sprouts leaves (Brassica oleracea var.gemmifera) is sufficient to obtain attraction of the parasitoidCotesia glomerata or whether feeding byPieris brassicae caterpillars elicits the release of synomones not produced by mechanically damaged leaves. The response of the parasitoidCotesia glomerata to different types of simulated herbivory was observed. Flight-chamber dual-choice tests showed that mechanically damaged cabbage leaves were less attractive than herbivore-damaged leaves and mechanically damaged leaves treated with larval regurgitant. Chemical analysis of the headspace of undamaged, artificially damaged, caterpillar-infested, and caterpillar regurgitant-treated leaves showed that the plant responds to damage with an increased release of volatiles. Greenleaf volatiles and several terpenoids are the major components of cabbage leaf headspace. Terpenoids are emitted in analogous amounts in all treatments, including undamaged leaves. On the other hand, if the plant is infested by caterpillars or if caterpillar regurgitant is applied to damaged leaves, the emission of green-leaf volatiles is highly enhanced. Our data are in contrast with the induction of more specific synomones in other plant species, such as Lima bean and corn.
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  • 76
    Digitale Medien
    Digitale Medien
    Springer
    World journal of microbiology and biotechnology 10 (1994), S. 406-409 
    ISSN: 1573-0972
    Schlagwort(e): Bacillus cereus-diarrhoeal-type enterotoxin ; Bacillus thuringiensis ; Coleoptera ; Diptera ; Lepidoptera ; thuringiensin
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Abstract At moderate concentration, 23 of 40 strains of Bacillus thuringiensis isolated from Sweden were toxic to Trichoplusia ni and five were toxic to Aedes aegypti. Five of the strains were toxic to Diabrotica undecimpunctata at high concentration, two were toxic to Heliothis virescens at low concentration and five produced thuringiensin (formerly called β-exotoxin). No strain was toxic towards the beet armyworm Spodoptera exigua at low concentration. Twenty-three of the strains produced a B. cereus-diarrhoeal-type enterotoxin.
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  • 77
    Digitale Medien
    Digitale Medien
    Springer
    Geotechnical and geological engineering 12 (1994), S. 113-121 
    ISSN: 1573-1529
    Schlagwort(e): Greywacke ; normal stress ; rockfill ; shear strength ; stability ; triaxial testing
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie
    Notizen: Summary Accurate stability analysis must consider the variation of the angle of friction of rockfill with the confining pressure. In reality, with increasing depth of a rockfill dam, the apparent friction angle decreases, whereas near the surface it tends to be higher. Conventional methods which employ a constant friction angle throughout the depth of a rockfill shell often yield a lower factor of safety (conservative) for shallow slip planes. On the contrary, they produce a higher factor of safety for deepseated slips subjected to increased normal (confining) stresses. This paper compares the constant friction angle approach with the variable friction angle method based on the stability analysis of a large rockfill dam, and the associated practical implications are discussed. In the latter analysis, the effect of normal stress on the friction angle of rockfill is incorporated through experimental observations.
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  • 78
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical ecology 20 (1994), S. 125-133 
    ISSN: 1573-1561
    Schlagwort(e): Bombyx mori ; Lepidoptera ; Bombiridae ; silkworm ; larvae ; ecdysone ; 20-hydroxyecdysone ; feeding behavior ; electrophysiology ; sensilla response ; chemoreceptors
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract The feeding and gustatory responses to ecdysone and 20-hydroxyecdysone were investigated in the silkworm,Bombyx mori. 20-Hydroxyecdysone reduced feeding response strongly in fourth- and fifth-instar larvae, whereas ecdysone had no effect on feeding response. 20-Hydroxyecdysone stimulated the R receptor, the receptor to feeding deterrents, to a great degree. By contrast, ecdysone was much less effective for stimulating the R receptor. These results indicate that ecdysone and 20-hydroxyecdysone have different effects on feeding response due to different interactions with mouthpart chemoreceptors.
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  • 79
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical ecology 20 (1994), S. 183-198 
    ISSN: 1573-1561
    Schlagwort(e): Induced resistance ; protein quality ; Helicoverpa zea ; soybean ; Glycine max ; protease inhibitor ; lipoxygenase ; Lepidoptera ; noctuidae
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Resistance in soybean toHelicoverpa zea is comprised of both constitutive and inducible factors. In this study, we investigated the induction of resistance byH. zea in both greenhouse and field studies. In a greenhouse experiment, fourth-instarH. zea growth rates were reduced by 39% after 24 hr feeding and by 27% after 48 hr when larvae fed on previously wounded V3 foliage (cv. Forrest) compared with undamaged foliage. In a field study, the weight gain by larvae was more than 52% greater when larvae fed for 72 hr on undamaged R2/R3 soybean plants (cv. Braxton) compared to those that fed on previously wounded plants. A significant component of the induced resistance is due to a decline in the nutritional quality of foliar protein following foliar damage byH. zea. Foliar protein was extracted from damaged and undamaged foliage and incorporated into artificial diets. Larval growth was reduced 26% after four days and 49% after seven days on diets containing protein from damaged plants compared to larvae feeding on foliar protein from undamaged plants. Chemical analyses of protein quality also indicated a decline in quality in damaged plants compared to unwounded plants. Increases in lipoxygenase activity (53%), lipid peroxidation products (20%), and trypsin inhibitor content (34%) were observed in protein from wounded plants. Moreover, a 5.9% loss in free amines and 19% loss in total thiols occurred in protein from wounded plants. Larval feeding causes a significant increase in foliar lipoxygenase activity that varied among genotypes. Lipoxygenase isozymes were measured at pH 5.5, pH 7.0, and pH 8.5 in V3 stage plants of Forrest, Hark, D75-1069, and PI 417061 genotypes. Lipoxygenase activity in each genotype was significantly increased after 72 hr of larval feeding at each pH level tested, with the exception of lipoxygenase isozymes at pH 5.5 in genotype PI 417061. Larval feeding on R2/R3 stage plants (field-grown cv. Braxton) for six days also increased foliar lipoxygenase activity.
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  • 80
    ISSN: 1573-1561
    Schlagwort(e): Lepidoptera ; Geometridae ; Lambdina athasaria ; Lambdina fiscellaria fiscellaria ; Lambdina fiscellaria lugubrosa ; sex pheromone ; synergism ; 7,11-dimethylheptadecane ; 7-methylheptadecane ; 5,11-dimethylheptadecane
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Two methylated hydrocarbons, 7-methylheptadecane (7) and 7,11-dimethylheptadecane (7,11), are female sex pheromone components of the spring hemlock looper (SHL),Lambdina athasaria (Walker). Compounds extracted from female pheromone glands were identified by coupled gas chromatographic-electroantennographic detection (GC-EAD) and coupled GC-mass spectrometry (GC-MS) in selected ion monitoring mode. In field trapping experiments, (7) and (7,11) by themselves were behaviorally inactive, but in combination attracted numerous male moths. (5,11)-Dimethylheptadecane (5,11) was detected in female SHL pheromone gland extracts, but did not enhance attraction to the binary blend of (7) and (7,11). The sex pheromone of SHL is related to that of congeneric eastern hemlock looper (EHL),Lambdina fiscellaria fiscellaria (Guen.) [(5,11) and 2,5-dimethylheptadecane (2,5)] and western hemlock looper (WHL),L.f. lugubrosa (Hulst) [(5,11), (2,5) and (7)]. Specificity of the pheromonal blend, spatial separation of coseasonal EHL and WHL, and temporal separation of sympatric EHL and SHL contribute to reproductive isolation.
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  • 81
    ISSN: 1573-1561
    Schlagwort(e): Cranberry fruitworm ; Lepidoptera ; Pyralidae ; Acrobasis vaccinii ; sex pheromone ; (E,Z)-8,10-pentadecadien-l-ol acetate ; (E)-9-pentadecen-l-ol acetate
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract The following compounds and (approximate ratios) were identified in sex pheromone gland extracts of femaleAcrobasis vaccinii Riley by comparison of gas chromatography-mass spectrometric traces with those of synthetic standards: (E,Z)-, (Z,E)-, (Z,Z), and (E,E)-8, 10-pentadecadien-l-ol acetates (100:1:2:12), a dodecen-l-ol acetate (8), (Z)-8-, (Z)-9-, and (E)-9-pentadecen-l-ol acetates (3:23:4), two heptadecen-l-ol acetates (4:4), tetradecyl, pentadecyl, hexadecyl, and heptadecyl acetates (3:15:10:8), dodecan-l-ol (6), tetradecan-l-ol (5), and hexadecan-l-ol (23). The amount of (E,Z)-8, 10-pentadecadien-l-ol acetate (E8,Z10–15:Ac) in the extract was about 0.5 ng/female. Electroantennographic analysis of gas chromatographic fractions of female sex pheromone gland extract showed that the fraction containingE8,Z10–15:Ac elicited the greatest response. Alone,E8,Z10–15:Ac failed to elicit upwind flight of males in flight-tunnel tests, and traps baited with it did not catch males in field experiments. WhenE8,Z10–15:Ac was combined with (E)-9-pentadecen-l-ol acetate (100:4), male upwind flight response in flight-tunnel tests was equivalent to those obtained with extract of female sex pheromone glands (synthetic, 62%; natural, 51%), but the percent of males flying upwind that contacted the source was lower (synthetic, 47%; natural, 88%). The lower percent of source contact elicited by the synthetic pheromone could be a result of the difference in isomer ratios of 8,10–15:Ac in the natural and synthetic pheromone or could indicate that the synthetic pheromone is incomplete. Traps baited with the 100:4 combination caught large numbers of males in field experiments.
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  • 82
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical ecology 20 (1994), S. 395-405 
    ISSN: 1573-1561
    Schlagwort(e): Douglas fir ; Pseudotsuga menziesii ; galactose ; terpenes ; sugars ; carbohydrates ; resistance ; western spruce budworm ; mortality ; Choristoneura occidentalis ; Lepidoptera ; Tortricidae
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract The current year's growth of Douglas fir contains galactose, unusual in that this carbohydrate makes up 78.7% of the total carbohydrate fraction. An agar diet study was undertaken to determine the effects of galactose, other carbohydrates, and terpenes on western spruce budworm larval mortality, growth rate, and adult biomas production. All concentrations of the carbohydrates and terpenes tested, as well as other mineral elements not tested, were typical of the current year's foliage of Douglas fir. In experiment I, the diet containing 5.61% total carbohydrate did not significantly affect larval mortality when compared to the control diet. However, diets containing 9.45% and 15% total carbohydrate concentrations significantly increased larval mortality 64% and 96.1%, respectively, when compared to the control. Also in experiment I, terpenes alone (78.9% morality) and terpenes in combination with 9.45% and 15% total carbohydrates significantly increased larval mortality (97.2% and 100%, respectively) when compared to mortality on the control diet (44%). To determine which carbohydrate was causing the adverse effect, 6% glucose, 6% fructose, and 6% galactose were placed individually and in combination with terpenes in diets in experiment II. The 6% galactose diet significantly increased larval mortality and reduced growth rate when compared to the control, glucose, and fructose diets. Glucose resulted in 16% less larval mortality, significantly enhanced female larval growth rate and pupal weight, but did not affect male larval growth rate and pupal weight, when compared to the control. Fructose resulted in a significant decrease in larval mortality and a general trend of enhanced female and male larval growth rate and pupal weight. Larval mortality on terpenes alone was not significantly different from the control, but terpenes with 6% galactose increased larval mortality and decreased female and male growth rate and pupal weight significantly when compared to glucose-terpene and fructose-terpene diets. No significant interactions were found between carbohydrates and terpenes in either experiment.
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  • 83
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical ecology 20 (1994), S. 579-591 
    ISSN: 1573-1561
    Schlagwort(e): Aldehydes ; formulation ; 10,12-hexadecadienal ; 10,12,14-hexadecatrienal ; moth ; Manduca sexta ; Lepidoptera ; Sphingidae ; tobacco hornworm ; trapping
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract In field experiments traps were baited with live females or with a two-, four-, or eight-component blend of the 16-carbon aldehydes previously identified as components of the sex pheromone emitted by femaleManduca sexta moths. The blends were formulated on rubber septa. Traps baited with a blend of all eight aldehydes captured moreM. sexta males than any other treatment. Septa loaded with 600 μg of the eight-component blend were attractive to males for about seven days in the field. Septa loaded with the eight-component blend and stored in a refrigerator at 4°C for a year released the conjugated diene and triene aldehydes at the same rate as freshly prepared septa and were equally attractive in the field.
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  • 84
    ISSN: 1573-1561
    Schlagwort(e): Sex pheromone ; attraction inhibitor ; behavioral antagonist ; mating disruption ; air permeation ; field EAG ; Cydia nigricana ; Tortricidae ; Lepidoptera ; pea moth ; (E,E)-8,10-dodecadien-1-yl acetate
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Synthetic sex pheromone of the pea mothCydia nigricana, (E,E)-8,10-dodecadien-1-yl acetate (E8,E10–12: Ac), was applied in polyethylene dispensers at a rate of 30 g/ha and 600 dispensers/ha in a 0.6-ha pea field. The release rate ofE8,E10–12: Ac was 140 mg/ha/day after six days, and 82 mg/ha/day after 20 days. Aerial concentrations ofE8,E10–12: Ac, as measured by a portable EAG apparatus, ranged from 2 ± 2 to 7 ± 3 ng/m3. The antennal signal was high and rather constant within pea canopy, but was lower and fluctuated strongly above canopy. Initially, 〉99% isomerically pureE8,E10–12: Ac was released, and male moths were attracted to dispensers. After nine days, isomeric blend composition had equilibrated to approx. 92%E8,E10–12: Ac and 8% of the inhibitory isomersE,Z-,Z,E-, andZ8,Z10–12: Ac. Males were then repelled from the pheromone-permeated field. Traps baited with 100 µgE8,E10–12: Ac caught 258 ± 133C. nigricana males/trap in the control, but no males at all in the disruption field.
    Materialart: Digitale Medien
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  • 85
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical ecology 20 (1994), S. 929-942 
    ISSN: 1573-1561
    Schlagwort(e): Centaurea maculosa ; sesquiterpene lactone ; cnicin ; host-plant selection ; oviposition behavior ; antifeedant ; attractant ; Spodoptera littoralis ; Agapeta zoegana ; Stenodes straminea ; Pterolonche inspersa ; Lepidoptera ; Noctuidae ; Cochylidae ; Pterolonchidae
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract The sesquiterpene lactone cnicin was extracted fromCentaurea maculosa andCentaurea vallesiaca. We examined its effects on the ovipositional response and larval development of generalist and specialist insect herbivores associated withC. maculosa. For the oviposition trials, three plant species (C. maculosa, Achillea millefolium, andCichorium intybus), half of which were sprayed with 3% of cnicin, were exposed to the specialist mothsStenodes straminea, Agapeta zoegana, andPterolonche inspersa in field cages. All three species significantly preferredC. maculosa to other plants andP. inspersa significantly preferred cnicin-sprayed plants to untreated plants for oviposition. Tested over all species, cnicin significantly increased the number of eggs laid on a given plant. A larval diet test examined the toxicity of cnicin for larvae of the generalist noctuid mothSpodoptera littoralis. Cnicin concentrations of 3% and 6% were lethal and 1% and 0.5% seriously inhibited growth and development. The larvae of theC. maculosa specialistStenodes straminea survived at 6% cnicin, but none of the pupae hatched.Agapeta zoegana was able to survive at 1% and 3% cnicin. Both specialists had difficulties with the artificial diet, but weight increase and survival was not further reduced when cnicin was present compared with on the control diet. In conclusion, cnicin influenced host recognition by the specialist species, and larvae of the generalist did not survive on natural levels of cnicin. Growth and survival of the specialist were not influenced by cnicin but were considerably hampered on artificial diet.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 86
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical ecology 20 (1994), S. 1025-1037 
    ISSN: 1573-1561
    Schlagwort(e): Pieris rapae ; Pieris napi oleracea ; Lepidoptera ; Pieridae ; oviposition ; stimulants ; glucosinolates
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract The relative activities of 10 glucosinolates in stimulating oviposition byP. rapae andP. napi oleracea were compared under the same conditions. When tested at the same concentration, the structurally different glucosinolates stimulated both butterfly species to widely varying degrees. In most cases,P. rapae was more sensitive to aromatic and indole glucosinolates than to aliphatic representatives. This species responded even less to alkyl thio and sulfinyl glucosinolates. However,P. napi oleracea responded strongly to these aliphatic and sulfur-containing members of the group, and the relative activities of aromatic and aliphatic glucosinolates did not show a clear pattern for this species.P. napi oleracea was much more sensitive to low concentrations of sinigrin than wasP. rapae. The threshold concentration for response ofP. napi oleracea to sinigrin was 10−8 M, which was 100 times lower than forP. rapae, butP. rapae was more sensitive thanP. napi oleracea to changes in glucosinolate concentrations. For bothPieris species, an optimal concentration was reached, above which the response remained constant or tended to decrease.
    Materialart: Digitale Medien
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  • 87
    ISSN: 1573-1561
    Schlagwort(e): Cotesia rubecula ; Hymenoptera ; Braconidae ; Lepidoptera ; Pieridae ; Plutellidae ; Pieris rapae ; Brassica oleracea ; Plutella xylostella ; Phaselus vulgaris ; Geranium molle ; tritrophic interactions ; infochemicals ; volatiles
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract The role of airborne infochemicals in host selection by the parasitoidCotesia rubecula (Marshal) (Hymenoptera: Braconidae) was examined in a wind tunnel. To elucidate the role of volatile chemicals in attractingC. rubecula to cabbage infested by the host [Pieris rapae L. (Lepidoptera: Pieridae)], the potential sources of volatiles related toP. rapae infestation on cabbage were tested individually. The responses of females to nonhost plant species, bean and geranium, as well as to frass of a nonhost lepidopteran were also examined.C. rubecula was attracted to cabbage previously infested byP. rapae and to frass and regurgitate ofP. rapae. No attraction was observed to larvae ofP. rapae alone. Females were also attracted to mechanically damaged cabbage, cabbage previously infested byPlutella xylostella L. (Lepidoptera: Plutellidae) (a nonhost lepidopteran herbivore), and cabbage previously infested by snails (a nonhost, noninsect herbivore). Intact cabbage, bean, and geranium plants elicited no attraction. A low frequency of attraction was observed to mechanically damaged bean and geranium. Attraction was also observed to frass ofP. xylostella. Volatiles from cabbage related to damage, and volatiles from frass and regurgitate of the host seem to play an important role in guidingC. rubecula to plants infested by its host.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 88
    ISSN: 1573-1561
    Schlagwort(e): Cotesia rubecula ; Hymenoptera ; Braconidae ; Lepidoptera ; Pieridae ; Plutellidae ; Pieris rapae ; Plutella xylostella ; Helix aspera ; Brassica oleracea ; Phaseolus vulgaris ; tritrophic interactions ; synomones ; infochemicals
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract The responses of the parasitoidCotesia rubecula to differently damaged cabbages were recorded during a series of choice tests. To determine if flyingC. rubecula can discriminate differences in the blend of volatiles emitted by cabbages damaged by different causes and how plant volatiles released from a distant source affect the searching behavior ofC. rubecula once searching on a plant, wasps were presented with a choice of plants located one behind the other and separated by a distance of 15 cm. The sources of damage were: cabbage damaged by the host (Pieris rapae), by a nonhost lepidopteran herbivore (Plutella xylostella), by a nonhost, noninsect herbivore (snail), and by mechanical means. The results showed that the site of first landing and the time spent searching on the leaves was influenced by the type of damage inflicted on plants. Wasps preferred to land on cabbages damaged by host and nonhost species of Lepidoptera over those damaged by snails and mechanical means. No preference was observed for first landing between cabbages damaged by the two species of Lepidoptera or between cabbages damaged by snails and mechanical means. Cabbage damaged byP. rapae was searched most intensively, followed by cabbage damaged byP. xylostella, cabbage damaged by snails, and cabbage damaged by mechanical means.C. rubecula differentiates between the volatile blends emitted by differently damaged cabbages, and it is attracted to volatiles related to recent lepidopteran damage. Wasps searched longer on freshly damaged than on leaves with older damage.
    Materialart: Digitale Medien
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  • 89
    ISSN: 1573-1561
    Schlagwort(e): Galleria mellonella ; Apis mellifera ; Pyralidae ; Apidae ; Lepidoptera ; Hymenoptera ; greater wax moth ; honeybee ; propolis ; plant resins ; phenolics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Bee propolis is a sticky amalgamation of plant resins collected by honeybees (Apis mellifera L.) and used in the hive for filling cracks and repairing combs. Propolis contains a diversity of compounds of plant origin, and is reported to have medicinal, antimicrobial, insecticidal, and phytotoxic properties. We examined the physical and chemical composition of North American samples of bee propolis from several sites in North America and tested for bioactivity against larvae of the greater wax moth (Galleria mellonella L.), a common apiary pest. The amount of methanol-extractable resin in samples from Ohio and Georgia ranged from 24% to 79% by weight. Propolis collected from hives in Ohio was more chemically diverse (over 30 compounds detected by paper chromatography) than material from south Georgia (fewer than 10 major compounds) and contained a lower proportion of methanol-insoluble beeswax. The paper chromatographic surveys revealed little variation in the chemical profile of specific hives over a six-month period and no differences between propolis from adjacent hives. Four flavonoids were identified from propolis collected in Ohio: kaempferol, galangin, 3,3′-dimethoxyquercetin and 3-methoxykaempferol. When mixed into artificial diet, fractionated propolis reduced larval growth of the greater wax moth, but not dramatically. An array of phenolics reported from propolis (caffeic acid, chrysin, ferulic acid, galangin, kaempferol, and quercetin) were bioassayed individually for effects on larvae, but none reduced larval growth at the concentrations tested, suggesting that wax moths are tolerant of some phenolics in their diet.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 90
    ISSN: 1573-1561
    Schlagwort(e): Pieris rapae ; Lepidoptera ; Pieridae ; Plutellidae ; Plutella xylostella ; Cotesia rubecula ; Hymenoptera ; Braconidae ; Brassica oleracea capitata ; infochemicals ; plant volatiles
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract To elucidate the identity of the volatile compounds that could be involved in the searching behavior of the parasitoidCotesia rubecula Marshall (Hymenoptera: Braconidae), the volatiles released by cabbage and frass of Lepidoptera feeding on cabbage were collected and analyzed using a gas chromatograph-mass spectrometer. The volatiles emitted by intact cabbage were α-pinene, β-pinene, myrcene, 1,8-cineole,n-hexyl acetate,cis-3-hexen-1-yl acetate, and dimethyl trisulfide. Mechanical damage on an intact plant induced the release of two more compounds,trans-2-hexenal and 1-methoxy-3-methylene-2-pentanone. Current feeding by larvae ofPieris rapae L. (Pieridae) induced the plant to release all the compounds released after mechanical damage and additionally 4-methyl-3-pentenal and allyl isothiocyanate. Current feeding by larvae ofPlutella xylostella L. (Plutellidae) induced the plant to release all the compounds present after mechanical damage and additionally allyl isothiocyanate. The volatiles emitted after feeding by the lepidopterans had ceased were the same as those emitted by cabbage damaged by mechanical means. The blend of volatiles emitted by frass was comprised of plant chemicals, mainly sulfur compounds. Frass ofP. rapae emitted allyl isothiocyanate, methyl isothiocyanate, methyl propyl sulfide, dimethyl trisulfide,S-methyl methane thiosulfinate, 4-methyl-3-pentenal,trans-2-hexenal, and 2,3-dihydro-4-methyl furan. Frass ofP. xylostella emitted only dimethyl trisulfide andS-methyl methane thiosulfinate. The blend of volatiles emitted by frass is herbivore-species specific.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 91
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical ecology 20 (1994), S. 1985-2001 
    ISSN: 1573-1561
    Schlagwort(e): Lepidoptera ; Lasiocampidae ; Malacosoma disstria ; Orgyia leucostigma ; larva ; tannin ; tannic acid ; peritrophic membrane ; oxidation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Final-instarMalacosoma disstria fed artificial diets containing tannic acid develop lethal pupal deformities. We examined some of the factors potentially underlying tannin sensitivity in this species, including the permeability of the peritrophic envelope to tannic acid and the chemical fate of tannic acid in the gut. Tannic acid does not penetrate the peritrophic envelope ofM. disstria, demonstrating that the containment of tannic acid within the endoperitrophic space is not sufficient to protect an insect herbivore from the adverse effects of ingested tannins. Ingested tannic acid undergoes extensive chemical modification in the midgut. Only 19–21 % of the high molecular weight components of the tannic acid ingested was recovered in the frass. Of two possible chemical fates of ingested tannic acid, oxidation is the predominant chemical transformation, whereas little hydrolysis occurs. Measurements of gut redox parameters showed that conditions in the midgut favor the oxidation of phenols. However, similar conditions occur in the midguts ofOrgyia leucostigma, in which no oxidation occurs. Therefore, oxidizing gut redox conditions do not necessarily lead to polyphenol oxidation in lepidopteran larvae. We conclude that the sensitivity ofM. disstria to ingested tannins is a consequence of their oxidation in the midgut.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 92
    ISSN: 1573-1561
    Schlagwort(e): Apiaceae ; Peucedanum ; Lepidoptera ; Noctuidae ; Spodoptera littoralis ; HPLC ; preparative isolation ; furocoumarins ; furanocoumarins ; pyranocoumarins ; growth inhibition ; dietary utilization ; plant chemical diversity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Peucedanum arenarium Waldst. & Kit.,P. austriacum (Jacq.) Koch,P. coriaceum Reichenb.,P. longifolium Waldst. & Kit,P. officinale L.,P. oreoselinum (L.) Moench,P. ostruthium L., andP. palustre (L.) Moench accumulate different structural types of coumarins including simple coumarins, linear furanocoumarins, linear dihydropyranocoumarins, angular dihydrofuranocoumarins and angular dihydropyranocoumarins. Linear furanocoumarins, known for various biological activities, include some well-known antifeedants, such as bergapten, isopimpinellin, and xanthotoxin. The aim of this investigation was to screen the diverse coumarins fromPeucedanum for insecticidal activity. LC was used to analyze and isolate coumarins for the bioassays. A growth inhibition bioassay with 17 derivatives, comprising all structural types fromPeucedanum, carried out withSpodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae) as test organism, indicated the majority of the linear furanocoumarins and the angular dihydrofuranocoumarin athamantin as active compounds. Oxygenation of the prenyl residue of linear furanocoumarins decreased activity. Further formation of an ester with angelic acid even resulted in complete inactivity. Five active linear furanocoumarins, bergapten, isopimpinellin, xanthotoxin, isoimperatorin, and imperatorin, and two linear furanocoumarins with a substituted furan ring, peucedanin and 8-methoxypeucedanin, were compared in a dietary utilization bioassay. Relative growth rate (RGR) and relative consumption rate (RCR) divided the tested coumarins in three groups of similar activity. Isopimpinellin and peucedanin slightly decreased RGR and RCR of the treated larvae, and xanthotoxin, isoimperatorin, and 8-methoxypeucedanin heavily decreased RGR and RCR. Bergapten and imperatorin differed by the lowest RGR values and rather high RCR values. The effects caused by these two coumarins indicate specific postingestive toxicity. The results obtained in this study add to the reputation of coumarins to be an effective chemical defense, postulating that chemical diversity is a necessary trait for well-defended plants.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 93
    ISSN: 1573-1561
    Schlagwort(e): Lepidoptera ; Pyralidae ; Chilo partellus ; spotted stem borer ; female sex pheromone ; (Z)-11-hexadecenal ; (Z)-11-hexadecen-1-ol ; multicomponent pheromones ; signal integrity ; dispensing technique ; trap efficiency ; proximity effect
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract The effect of proximity of the release points of the two pheromone components (Z)-11-hexadecenal and (Z)-11-hexadecen-1-ol of the spotted stem borer,Chilo partellus (Lepidoptera: Pyralidae) on behavior of the males and on trapping efficiency was investigated. Separating the dispensers of the two components in the trap by a mere 3 cm resulted in a threefold decrease in trap performance, compared to very close release of the components. The result is attributed to possible distortion of the pheromone signal, resulting in confused behavior ofC. partellus males in the vicinity of the trap. The ethological and practical implications of the phenomenon are discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 94
    Digitale Medien
    Digitale Medien
    Springer
    Multidimensional systems and signal processing 5 (1994), S. 307-318 
    ISSN: 1573-0824
    Schlagwort(e): Eigenvalue ; matrix ; polytope ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract A simple geometric test can be applied to evaluateG-stability of a polytope of matrices. In case of a regionG being a convex subset of the complex plane, it suffices to assume that four (for some regions even less) corner points of a certain rectangle are contained inG.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 95
    Digitale Medien
    Digitale Medien
    Springer
    Euphytica 75 (1994), S. 215-220 
    ISSN: 1573-5060
    Schlagwort(e): PCR ; polymorphisms ; DNA ; RAPDs ; rye ; Secale cereale ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Cultivar specific DNA profiles in rye were revealed by polymerase chain reaction (PCR) using randomly amplified polymorphic DNA (RAPD) sequences. Ten base primers were used for the amplification of genomic DNA of rye cultivars by PCR. RAPD analysis was found to be reproducible among samples between PCR runs. When amplification profiles of different rye cultivars were compared using various primers, the overall profiles were cultivar specific. However, not all primers revealed polymorphisms. These primers appear to amplify conserved sequences in all rye cultivars. Intracultivar studies were conducted on two of the cultivars. In the cultivar Imperial, no polymorphisms were observed among ten plants analyzed with five primers. In the cultivar Balboa, polymorphisms were observed among fifty plants with four of the ten primers analyzed. Despite the small amount of intracultivar variability, RAPD analysis has the potential to be a rapid and reliable method of cultivar identification in this outcrossing species.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 96
    Digitale Medien
    Digitale Medien
    Springer
    Euphytica 77 (1994), S. 221-230 
    ISSN: 1573-5060
    Schlagwort(e): Variety trials ; progeny testing ; timothy ; stability ; G × E interactions ; adaptation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary A joint breeding project for the northern areas of Scandinavia and Iceland was initiated in 1981 under the auspices of the Nordic Council of Ministers. Initially, efforts concentrated on cooperative trials in which both early and more advanced breeding material was tested at a number of experimental stations in the northern regions. This was followed by a joint breeding programme for timothy with the primary aim of developing varieties that possess broad adaptation to a range of Nordic climates and managements and can be grown throughout the northernmost part of Scandinavia. Each of the five national breeding stations originally provided 12 timothy genotypes for the project giving a total of 60 genotypes. The parental genotypes were compared as spaced plants at all five stations and their polycross progeny were grown under sward conditions at the same sites. On the basis of results obtained from these field trials parent clones have been selected and intercrossed to form synthetic populations.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 97
    Digitale Medien
    Digitale Medien
    Springer
    Journal of optimization theory and applications 81 (1994), S. 277-296 
    ISSN: 1573-2878
    Schlagwort(e): Robust control ; min-max techniques ; synthesis methods ; stability ; multivariable control systems
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract An important (some say, the major) reason for using feedback control is the presence of uncertain parameters which are a natural part of any real dynamical model. In this paper, we consider uncertain constant parameters in a time-invariant linear plant and announce some new results concerning robust compensator synthesis. Using the min-max principle, we derive necessary conditions for fixed-order linear robust controllers assuring asymptotic stability or relative stability. These necessary conditions are an extension of the Lagrange multiplier method. This is achieved using a cost function based on the inverse of the so-called critical constraint. We present both matrix and polynomial versions; the latter allows controllers of fixed structure. We suggest a probability-one homotopy algorithm and solve some examples from the literature.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 98
    Digitale Medien
    Digitale Medien
    Springer
    Applied mathematics and mechanics 15 (1994), S. 1035-1045 
    ISSN: 1573-2754
    Schlagwort(e): mutual interference system ; bounded ; extermination equilibrium ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Mathematik , Physik
    Notizen: Abstract This paper considers a typical mutual interference system of four-dimensional species, its bounded, extermination stability are studied, and their necessary-sufficient condition are given, and their ecology meaning set forth.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 99
    Digitale Medien
    Digitale Medien
    Springer
    Applied mathematics and mechanics 15 (1994), S. 923-928 
    ISSN: 1573-2754
    Schlagwort(e): stability ; multi-scale perturbation method ; bifurcation from infinity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Mathematik , Physik
    Notizen: Abstract This paper applies the multi-scale perturbation method suggested by Ref. [3] to investigate the linear stability behavior of distorted plane Couette flow. Using this method, the unstable Tollmien-Schlichting wave in plane Couette flow can be found. but not the most unstable mode. By comparing the results of this paper with those of Ref. [3], the effectiveness of this method is investigated.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 100
    Digitale Medien
    Digitale Medien
    Springer
    Periodica mathematica Hungarica 29 (1994), S. 81-87 
    ISSN: 1588-2829
    Schlagwort(e): Primary 39 ; Secondary 58F ; Generalized logistic ; stability ; difference equations
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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