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  • 1985-1989  (18)
  • 1975-1979  (15)
  • 1970-1974  (10)
  • 1945-1949  (2)
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  • 11
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The reaction64Ni(36S,34Si)66Zn atE=198 MeV has been used to measure the mass excess of34Si; a value of −19.971 −0.044 +0.037 MeV was obtained. This result which is in agreement with the previous value (−19.85±0.30 MeV) is in excellent agreement with recent shell-model mass predictions. The result is discussed within the context of the proposed region of deformation aroundZ=11,N=20.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 45 (1989), S. 215-222 
    ISSN: 1420-9071
    Keywords: Behavior ; learning ; leaf surface ; wax ; insects ; food selection ; secondary compounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Direct observations on the feeding behavior of insect herbivores are uncommon, but important. The important aspects of host-plant selection by phytophagous insects that have been revealed by such observations are the role of chemicals in the leaf surface, and learning. There are few detailed reports of behavior at the leaf surface, but these indicate that many, if not all, insects exhibit behavior pattenrs that can be interpreted as an examination of the quality of the surface and acceptance or rejection may follow without further testing. A number of experiments show that chemicals from the leaf surface commonly contribute to the acceptability or otherwise of a plant and in most cases so far the active chemicals are of widespread occurrence, not having a specific association with the host plant. Some experiments show that the association between surface chemicals and plant palatability is learned, but in other cases there is evidence of an innate response. Habituation to deterrent chemicals has been demonstrated in the laboratory, but not in the field. Food aversion learning also occurs and may be important in dietary switching by polyphagous insects.
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 16 (1973), S. 329-342 
    ISSN: 1570-7458
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Alle Hauptnerven des Mund- und Rachennervensystems wurden kontrolliert reseziert. Erst wenn die rückwärtigen Rachennerven zerschnitten werden, nehmen die Insekten wesentlich mehr Nahrung zu sich. Solche Insekten versuchen längere Zeit zu fressen. Wenn sich während des Fressens der Vorderdarm füllt, wird keine Nahrung an den Mitteldarm weitergegeben und sein Vorderende ist der letzte Teil, der sich vollständig ausdehnt. Nach Durchtrennung der rückwärtigen Rachennerven sind alle Teile des Vorderdarms offen-sichtlich mehr gedehnt. Eine solche erhöhte Nahrungsaufnahme tritt aber nicht ein, wenn die Nahrung relativ ungünstig ist. Das Abbinden des Kropfes verursacht beim nachträglichen Fressen keine übermäßige Ausdehnung des Vorderteiles. Die Nahrungsaufnahme hat keinen Unterschied im Körpervolumen zur Folge und das Durchtrennen des ventralen Nervenstranges bleibt ohne Einfluß auf die nachträglich aufgenommenen Nahrungsmengen. Das vergrößerte Darmvolumen wird durch Kollaps des Luftsackes kompensiert.
    Notes: Abstract During the course of a meal by insects with an empty gut, food is held in the foregut and the midgut remains empty. The last part of the foregut to fill is the extreme anterior end of the crop, and stretch receptors in this region control the amount eaten. Cutting the posterior pharyngeal nerves isolates these receptors from the frontal garglion and results in hyperphagia pharyngeal nerves isolates these receptors from the frontal garglion and results in hyperphagia during one meal. On unfavourable food, when smaller amounts are eaten, distension of the foregut is not involved in regulating meal size. Feedback from receptors in the body wall is not important in regulating meal size; most of the increase in gut volume resulting from feeding is taken up by the collapse of the air sacs so that there is little or no change in the body volume.
    Type of Medium: Electronic Resource
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  • 14
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 13 (1970), S. 363-376 
    ISSN: 1570-7458
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Die Funktionen der Maxillartaster von Locusta migratoria migratorioides (R. & F.), Schistocerca gregaria (Forskål) und Chortippus parallelus (Zett.) wurden unter Anwendung verschiedener Verfahren untersucht. Die Tasterbewegungen wurden kinematographisch analysiert und als Schlagen und Tasten klassifiziert; das letztere tritt hauptsächlich kurz vor und nach, aber ebenso gut auch während der Nahrungsaufnahme auf. Die Sensillen an den Tasterenden berühren beim Tasten häufig das Substrat. Vorausgesetzt, daß die Insekten nicht gehungert hatten, wurde Bellis allein nach Betasten abgelehnt; nach längerem Hungern erfolgte jedoch die Ablehnung erst nach Beißen. Weitere Versuche, bei denen Extrakte der Kutikula von Poa oder Bellis verwendet wurden, zeigten, daß Annahme oder Ablehnung von der chemischen Natur des Substrats abhängen, welches von den Tastern berührt wird. Betasten eines geeigneten Substrats führte nicht unmittelbar zum Beißen, ruft aber eine Verhaltensweise hervor, die ihrerseits das Beißen fördert. Daraus wird geschlossen, daß die von den Tastern wahrgenommenen chemischen Reize für die Nahrungswahl der Acrididen wichtig sind, wenn die Insekten normal fressen. Nach Hunger ruft mechanische Reizung der Taster oder anderer Mundteile Beißen auch beim Fehlen geeigneter chemischer Reize hervor. Die häufigen kurzen Kontakte der Palpen mit dem Substrat während des Tastens erlauben offenbar den Sensillen, einen beständigen Strom von Informationen an das Zentralnervensystem zu liefern, ohne selbst angepaßt (ermüdet) zu werden.
    Notes: Abstract The functions of the maxillary palps of acridids have been investigated in experiments with Locusta migratoria migratorioides (R. & F.), Schistocerca gregaria (Forsk.) and Chorthippus parallelus (Zett.). The palp makes small irregular flicking movements and more extensive rapid vibrations described as palpation. Both activities involve the same basic movements of the palp segments. Palpation is essentially related to feeding and in normally feeding insects the palps play an important role in food selection, but as starvation is prolonged they become unimportant. Selection depends on appropriate chemical stimulation from the cuticle on the surface of the leaf. Palpation on this leads to head lowering and to biting if appropriate tactile stimuli are then received. The control of biting is discussed. The frequent but very brief, contacts of the sensilla on the tips of the palps with the substratum during palpation may enable them to relay information to the central nervous system more or less continuously without adapting.
    Type of Medium: Electronic Resource
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  • 15
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 37 (1985), S. 306-306 
    ISSN: 1570-7458
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 16
    ISSN: 1438-1168
    Keywords: Tantalum ; Niobium ; Titanium ; Columbite ; Rutile ; Mineralogy ; Geochemistry ; Pegmatite ; Austria ; Ostalpen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Description / Table of Contents: Zusammenfassung Titan-Ferrocolumbit ist ein seltenes Akzessorium in den Spodumenpegmatiten der Weinebene, Kärnten, Österreich. Er enthält entmischten niobhaltigen Rutil und selten Einschlüsse von möglicherweise primärem Zinnstein. Die Zusammensetzung des TitanFerrocolumbits ist relativ homogen und weist die folgenden Elementverhältnisse auf. Mn/(Mn + Fe) 0,24 – 0,33, Ta/(Ta + Nb) 0,09 – 0,13 (Atomverhältnisse) und 0,47 – 0,88 Ti pro 12 Kationen (2,7 - 5,0Gew.%TiO2). Natürlich auftretende Kristalle sind strukturell merklich ungeordnet und erlangen durch Erhitzen einen höheren Ordnungsgrad. Die Mn/(Mn + Fe) sowie Ta/(Ta + Nb) Verhältnisse des niobhaltigen Rutil betragen 0,00 – 0,04 bzw. 0,26 – 0,38. Der niobhaitige Rutil ist im Vergleich zu Mn- und Nb-führendem Ferrocolumbit an Fe, Ta, Ti und Sn angereichert.—Die Seltenheit von Nb, Ta-Oxiden in den spodumenführenden Pegmatiten der südlichen Ostalpen steht in Übereinstimmung mit ihrer Zugehörigkeit zum Albit-Spodumen Typ der selten-Element-führenden Pegmatite (rare-element pegmatites).
    Notes: Summary Titanian ferrocolumbite is a rare accessory mineral in the spodumene-bearing pegmatites at Weinebene, Carinthia, Austria. It contains abundant exsolved niobian rutile and scarce inclusions of cassiterite that may be primary. The titanian ferrocolumbite is relatively homogeneous with Mn/(Mn + Fe) 0.24–0.33, Ta/(Ta + Nb) 0.09–0.13 (atomic ratios) and 0.47–0.88 Ti per 12 cations (2.7–5.0 wt.% TiO2). Natural specimens are considerably disordered but become more ordered on heating. Niobian rutile has Mn/(Mn + Fe) 0.00–0.04 and Ta/(Ta + Nb) 0.26–0.38; it concentrates Fe, Ta, Ti and Sn relative to the Mn- and Nb-enriched ferrocolumbite. The overall scarcity of Nb, Ta-oxide minerals in the spodumene-bearing pegmatites of southern Ostalpen conforms to their general features ranking them with the albite-spodumene type of rare-element pegmatites.
    Type of Medium: Electronic Resource
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  • 17
    Electronic Resource
    Electronic Resource
    Springer
    Solar physics 38 (1974), S. 415-417 
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 18
    Electronic Resource
    Electronic Resource
    Springer
    Solar physics 43 (1975), S. 337-350 
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The spectral composition and spatial distribution of equatorial coronal emission near 304 Å is examined. Spectral scans indicate that the predominant line is from Si xi. Comparisons of observations with calculations of intensity changes with altitude indicate that collisional excitation is important near the Sun but that photoexcitation becomes dominant beyond about 1.3 R ⊙ from the solar center. Observed and calculated intensities are in approximate agreement for abundances and electron densities that are within the range of observed values.
    Type of Medium: Electronic Resource
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  • 19
    Electronic Resource
    Electronic Resource
    Springer
    Solar physics 53 (1977), S. 435-444 
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Data obtained by the OSO-7 spectroheliograph on strong XUV lines of five, different Fe ions from the outer equatorial corona are presented. Interpretation of the data with a spherically symmetric model atmosphere gives average ion abundances for lines of sight at 0.3R ⊙ from the limb. Fe xvi is usually more abundant than Fe xv, xiv, xii and ix, but there are times when Fe xii is more abundant than the other ions. The deviation of measured relative abundances of Fe xii, xiv, and xvi from predictions of ionization equilibrium at one temperature seems to indicate that there are appreciable temperature variations along lines of sight. Element abundances are very uncertain since they appear to depend so heavily on likely but unknown density irregularities along lines of sight.
    Type of Medium: Electronic Resource
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  • 20
    Electronic Resource
    Electronic Resource
    Springer
    Solar physics 42 (1975), S. 487-496 
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The abundance of Fe relative to H is obtained by using resonantly scattered intensities of λ 284 of Fe XV that were measured with OSO-7 and resonantly scattered intensities of Lα of H I that were obtained by Gabriel (1971). Because of possible differences in electron densities along lines of sight for these non-simultaneous measurements and in relative calibrations, results are rather uncertain but still indicate that the average Fe abundance relative to H in the corona appears to be at least as large as a recent photospheric abundance. Some limitations in using this method for obtaining abundances are examined for future experiments with simultaneous measurements and well calibrated detectors.
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