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  • Springer  (37)
  • Springer Nature  (8)
  • American Institute of Physics (AIP)  (7)
  • American Association for the Advancement of Science (AAAS)
  • 1985-1989  (53)
  • 1987  (53)
  • 1
    Electronic Resource
    Electronic Resource
    The responses of the spotted alfalfa aphid to variation between plants of an aphid-resistant lucerne cultivar (1987)
    Springer
    Entomologia experimentalis et applicata 44 (1987), S. 177-185 
    Details
    ISSN: 1570-7458
    Keywords: spotted alfalfa aphid ; Therioaphis trifolii ; aphid-resistant plants ; lucerne = alfalfa ; Medicago sativa ; variation ; bioassay ; antibiosis non-preference ; inter-plant movement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé L'étude de la multiplication initiale des effectifs de T. trifolii, élevés au laboratoire sur pousses de différents pieds de luzerne, a servi de test d'antibiose pour les cultures en plein champ. La distribution de l'antibiose, dans des échantillons importants de plantes appartenant à des cultivars sélectionnés pour leur résistance aux pucerons, a présenté une forme en J, c'est-à-dire que la majorité des plantes était très résistante, quelques unes apparemment sensibles, et un certain nombre intermédiaires entre ces deux extrêmes. Pour un niveau donné d'antibiose, la reproduction, la mortalité et ainsi la distribution initiale en âges dans les populations de pucerons ont été généralement identiques. La multiplication végétative de plantes présentant un gradient de résistance à l'intérieur d'un cultivar et l'utilisation d'un plan de distribution des boutures ont permis l'étude de ce qui semble être l'effet de l'hétérogénéité spatiale sur la résistance des cultures aux attaques de pucerons. La simulation d'une invasion de la culture par les pucerons en plaçant des adulte sur toutes les boutures d'un rang ne pouvait donner une explication de la croissance de la population que si les pucerons se déplacaient le long du rang pour découvrir et exploiter les pieds les plus sensibles. Une distribution par taches, comme on peut l'envisager dans un champ, ne devrait pas gêner les pucerons, car bien que les mouvements d'évasion soient stimulés par les niveaux de résistance élevés (de non-préférence), on peut en déduire que les pucerons se déplaceront sur des plantes très résistantes, eventuellement pour atteindre des plantes moins résistantes placées derriere.
    Notes: Abstract Initial population growth of spotted alfalfa aphid reared on shoots cut from individual lucerne plants, was tested and used as a realistic bioassay of antibiosis. Within cultivars selected for aphid-resistance there was a J-shaped distribution of antibiosis between plants of the crop, the majority being highly resistant, a few apparently susceptible and a proportion partly-resistant. For a given level of antibiosis, reproduction, mortality and thus initial age distribution of aphid populations were generally similar. Vegetative cloning of plants from the range of resistance available in a cultivar has allowed studies of the likely effect of spatial variation of resistance in crops on aphid infestations, using experimental arrays of cut shoots. Simulation of aphid invasion of crops by the placement of adults on all shoots of an array gave results explicable only if the aphids moved through the array to find and breed on the more susceptible plants. A patchy arrangement of these, as might be expected in a field crop, would not hinder the aphids, for although movement off a plant is stimulated by higher resistance (non-preference) levels, it was inferred that aphids will move onto higher resistance plants, eventually to reach lower resistance plants beyond.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00367627
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  • 2
    Electronic Resource
    Electronic Resource
    Time-of-flight x-ray photoconductivity of HgI2 (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 62 (1987), S. 4308-4310 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Time-of-flight photoconductivity measurements were performed on HgI2 using a penetrating, pulsed x-ray source, simulating the operation of photoconductive x-ray detectors. By examining a variety of HgI2 samples, a wide range of electron and hole mobilities were observed, but in all cases hole transport was highly localized, limiting the collection of the photocarriers in HgI2 detectors. The intrinsic photocarrier generation and recombination processes differed from classical Onsager and Langevin mechanisms observed in low-mobility photoconductors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.339059
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  • 3
    Electronic Resource
    Electronic Resource
    Intrusions in the active layer of channeled-substrate-planar laser diodes (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 62 (1987), S. 1093-1096 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Channeled-substrate-planar laser diodes from various wafers were observed to develop a node or dark spot in their near-field patterns after failure during lifetesting. "Node'' devices from each wafer were angle lapped and stained in an attempt to uncover a physical mechanism for this common failure symptom. Optical microscopic examination of the beveled cross sections revealed that an intrusion, in the form of a spike at the tip of the zinc diffusion front, had penetrated into the active layer of these diodes. The node observed in the near-field pattern appears to be in a position corresponding to the location of the spike in the active region. In addition, cathodoluminescence measurements on other "node'' diodes revealed a dark line region approximately 2 μm wide running parallel to and in the middle of the 5-μm contact stripe. We believe that this dark line region is representative of an area of nonradiative recombination which occurs in the portion of the active layer containing the intrusion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.339740
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  • 4
    Electronic Resource
    Electronic Resource
    Thin-film palladium and silver alloys and layers for metal-insulator-semiconductor sensors (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 62 (1987), S. 1074-1083 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The addition of Ag to Pd in the gate metal of a metal-insulator-semiconductor gas sensing diode can improve the performance and change the selectivity of the sensors for a variety of reactions. Data on the response of diodes with 12 different ratios of Ag to Pd in alloys and layers of Pd and Ag to hydrogen and other gases are reported. Diodes with as much as 32% Ag respond very well to H2 gas and the films are much more durable to high hydrogen exposure than pure Pd films. Improvements in the rate of response and aging behavior are found for certain Ag combinations; others give poorer performance. The presence of Ag on the surface changes the catalytic activity in some cases and examples of H2 mixed with O2 and/or NO2, propylene oxide, ethylene, and formic acid are given. Such selectivity forms the basis for miniature chemical sensor arrays which could analyze complex gas mixtures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.339738
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  • 5
    Electronic Resource
    Electronic Resource
    Electromagnetic resonance enhanced photoabsorption in planar metal–oxide–metal tunnel junction detectors (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 2022-2029 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present calculations of surface plasmon and guided wave enhanced light absorption in the metal electrodes of planar aluminum–aluminum oxide–silver and aluminum–aluminum oxide–aluminum tunnel junctions. We consider excitation, under conditions of attenuated total reflection, of both the "fast'' and "slow'' surface plasmons of the junction, and of TE and TM guided modes supported by a dielectric film adjoining the junction. We find that 〉97% absorption may be obtained at resonance in a single electrode of a practical device, the thickness of which is only a fraction of the expected photocarrier mean free path, and show how the angular width of the absorption peak may be varied by changing the adjacent dielectric media. We also show how resonant absorption may be used in a biased planar device for the detection of radiation at normal incidence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.337999
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  • 6
    Electronic Resource
    Electronic Resource
    Spin-wave polarization in single domain uranium selenide (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 3412-3414 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Spin waves in ferromagnetic USe have been measured by inelastic neutron scattering. Previous measurements on a multidomain USe sample show that the spin wave branch has a zone center frequency of ≈9 THz, and that the spin waves are intrinsically broad. New measurements on a single domain sample show that, in addition, the spin wave is unpolarized. This behavior is unlike that of a classical ferromagnet, in which the polarization is transverse, but similar to behavior observed in some singlet ground state systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.338763
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  • 7
    Electronic Resource
    Electronic Resource
    Islands of stability and complex universality relations (1987)
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 28 (1987), S. 60-63 
    Details
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: For complex mappings of the type z→λz(1−z), universality constants α and δ can be defined along islands of stability lying on filamentary sequences in the complex λ plane. As the end of the filament is approached, asymptotic values αN∼λN−1∞, δN/α2N∼1 are attained, where μ∞=λ∞(λ∞−2)/4, is associated with the limiting form of the universal function for that sequence, g(z)=1−μ∞z2. These results are complex generalizations of the real mapping case (applying to tangent bifurcations and windows of stability) where μ∞=2 and δ/α2→ (2)/(3) correspond to the filament running along the real axis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.527808
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  • 8
    Electronic Resource
    Electronic Resource
    ESR study of optically enhanced phase transition in (BEDT–TTF)3Ta2F11 (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 86 (1987), S. 1780-1788 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have identified an optically enhanced magnetic phase transition in the newly synthesized organic molecular charge transfer salt, (BEDT–TTF)3Ta2F11 (BEDT–TTF 3/4 bis-ethylenedithiolotetrathiafulvalene) by ESR absorption measurements in the X band microwave region. At room temperature, only a doublet state ESR absorption is observed, but below 30 K several triplet ESR absorptions appear. The orientation dependence of the ESR absorption under illumination at energies near the band gaps in the material (640 nm, T=12 to 5 K, H0〈0.34 T) indicates that there are rapid spin exchange processes with times τe〈10−8 s near 7 to 5 K along certain crystallographic directions with a temperature dependence suggesting spin-lattice relaxation times which proceed via Van Vleck "direct processes.'' This, to our knowledge, is the first case where the magnetic properties of a charge transfer salt are altered by the interaction with photons of energy equal to the band gaps in a low dimensional solid, providing a new, interesting way to investigate these materials.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.452178
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  • 9
    Electronic Resource
    Electronic Resource
    Piezoelectric activity in films of poly(1-bicyclobutanecarbonitrile) (1987)
    Springer
    Polymer bulletin 17 (1987), S. 135-136 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract We observed significant piezoelectric activity in cast films of poly(1-bicyclobutanecarbonitrile).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00256878
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  • 10
    Electronic Resource
    Electronic Resource
    The influence of temperature and photoperiod on the development, survival and reproduction of the sowthistle aphid, Hyperomyzus lactucae (1987)
    Springer
    Entomologia experimentalis et applicata 43 (1987), S. 31-38 
    Details
    ISSN: 1570-7458
    Keywords: development rate ; survival ; reproduction ; intrinsic rate of increase ; effect of temperature ; effect of photoperiod ; physiological time ; temperature limits ; Hyperomyzus lactucae ; Aphididae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé La durée du développement, le taux de survie et la fécondité en fonction de l'âge ont été suivis chez les virginipares aptères et ailés du puceron: Hyperomyzus lactucae L., élevé sur Sonchus oleraceus L., et soumis à différentes conditions de température et de lumière. A l'intérieur de la gamme de températures moyennes de 12,5 à 24°C, la vitesse de développement et le rythme de reproduction augmentent, tandis que la longévité et la fécondité totale diminuent. La relation entre la température et la durée du développement est presque linéaire, avec un seuil théorique de développement évalué à environ 2°C. Le taux intrinsèque d'accroissement est lié positivement à la température calculée sur une base quotidienne, mais la relation est inversée quand la température est mesurée sur une échelle physiologique. Pour des conditions d'élevage identiques, les ailés ont eu, dans l'ensemble, une durée de développement plus longue, un taux de reproduction et une fécondité totale plus faibles que les aptères. La comparaison des performances des pucerons sous thermopériodes ou températures constantes, ou entre les générations en conditions identiques, a montré (1) que les conditions subies par l'embryon dans la mère conditionnent la survie et le développement; (2) que les limites des températures tolérables changent en fonction du type et de l'amplitude des fluctuations de température. A 22°C, des modifications de la photopériode, dans la gamme; 12D:12L à 8D:16L, ont eu peu d'effet sur les performances des pucerons.
    Notes: Abstract The development time, survivorship and age-specific fecundity of apterous and alate virginoparae of the sowthistle aphid, Hyperomyzus lactucae (L.) (Homoptera: Aphididae), reared on Sonchus oleraceus L., were measured under various temperature and light regimes. Within the temperature range of daily means of 12.5–24°C, speed of development and reproductive rate increased, while life span and total fecundity decreased, with an increase in temperature. The relationship between temperature and rate of development was nearly linear, with a notional development threshold estimated at about 2°C. The intrinsic rate of increase (rm) was positively correlated with temperature when calculated on a daily basis, but was inversely related to temperature when measured on a physiological time scale. Alatae generally had a longer development time, and achieved a lower reproductive rate and life-time fecundity, than apterae reared under identical conditions. Comparison of aphid performance under constant and alternating temperature regimes, and between successive generations under the same regime, showed that (1) the conditions experienced by the aphid as an embryo within its mother are important in determining survival and development and (2) tolerable temperature limits vary with the pattern and amplitude of the fluctuations of temperature. At 22°C, changes of photoperiod within the range of 12D:12L to 8D:16L had little effect on aphid performance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00350372
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