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  • 1
    Electronic Resource
    Electronic Resource
    Untersuchung der Grundlagen für das Sintern von Kunststoffen (1980)
    Springer
    Rheologica acta 19 (1980), S. 633-641 
    Details
    ISSN: 1435-1528
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Summary The mechanisms which cause polymer particles in thermoplastics sintering to coalesce are considered with the aid of calculations and model tests. The tests were carried out with PP, PTFE, PMMA, and UHMPE, varying the external compressive forces, the temperature, and the particle dimensions. The coalescence described theoretically in terms of an energy balance, the Hertz surface pressure, and timedependent material data is confirmed to a high degree experimentally. Apart from that, investigations were carried out with real mouldings and on the healing of pores. The results can be presented as a nomogram or as a program for a table calculator.
    Notes: Zusammenfassung Die Mechanismen, die zum Zusammenwachsen von Polymerpartikeln beim Sintern mit thermoplastischen Kunststoffen führen, werden anhand von Berechnungen und Modellversuchen betrachtet. Die Untersuchungen wurden an PP, PTFE, PMMA und UHMPE bei Variation der äußeren Druckkräfte, der Temperatur und der Teilchenabmessungen durchgeführt. Das mittels Energieansatz, Hertzscher Flächenpressung und zeitabhängiger Stoffgrößen theoretisch beschriebene Zusammenfließen wird mit guter Übereinstimmung im Experiment bestätigt. Weiterhin werden Untersuchungen an realen Formteilen und zum Ausheilen von Poren beschrieben. Die Ergebnisse lassen sich komprimiert in Nomogrammform oder als Tischrechnerprogramm darstellen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01517517
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  • 2
    Electronic Resource
    Electronic Resource
    Sociality and the Rate of rDNA Sequence Evolution in Wasps (Vespidae) and Honeybees (Apis) (1998)
    Springer
    Journal of molecular evolution 47 (1998), S. 606-612 
    Details
    ISSN: 1432-1432
    Keywords: Key words: Vespidae —Apis— Mitochondrial DNA — Nuclear DNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. Sequence data of mitochondrial 16S ribosomal DNA (mt-rDNA) and nuclear 28S ribosomal DNA (nuc-rDNA) were compared in two honeybee species (Apis mellifera and Apis dorsata) and a selection of 22 wasp species (Vespidae) with different levels of sociality. The averge substitution rates in mt-rDNA and nuc-rDNA were almost-equal in solitary species. In species with larger nests, however, the difference between the nuclear and the mitochondrial substitution rate significantly increased. The average substitution ratio, ψ (nucleotide substitutions in mt-rDNA/nucleotide substitutions in nuc-rDNA) was 1.48 ± 0.12 (SE) among the solitary Eumeninae, 3.70 ± 0.15 among five primitive social Stenogastrinae species, 3.24 ± 0.20 among five Polistinae species, 5.76 ± 0.33 among nine highly eusocial Vespinae, and 12.7 in the two Apis species. The high egg-laying rate and the effective population size skew between the sexes may contribute to the rise of the substitution ratio in the highly eusocial species. Drift and bottleneck effects in the mitochondrial DNA pool during speciation events as well as polyandry may further enhance this phenomenon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00006417
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  • 3
    Electronic Resource
    Electronic Resource
    Identified nonspiking interneurons in leg reflexes and during walking in the stick insect (1994)
    Springer
    Journal of comparative physiology 174 (1994), S. 685-700 
    Details
    ISSN: 1432-1351
    Keywords: Nonspiking interneurons ; Common inhibitor ; Walking ; Local and intersegmental reflexes ; Motor pattern
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract In the stick insect Carausius morosus identified nonspiking interneurons (type E4) were investigated in the mesothoracic ganglion during intraand intersegmental reflexes and during searching and walking. In the standing and in the actively moving animal interneurons of type E4 drive the excitatory extensor tibiae motoneurons, up to four excitatory protractor coxae motoneurons, and the common inhibitor 1 motoneuron (Figs. 1–4). In the standing animal a depolarization of this type of interneuron is induced by tactile stimuli to the tarsi of the ipsilateral front, middle and hind legs (Fig. 5). This response precedes and accompanies the observed activation of the affected middle leg motoneurons. The same is true when compensatory leg placement reflexes are elicited by tactile stimuli given to the tarsi of the legs (Fig. 6). During forward walking the membrane potential of interneurons of type E4 is strongly modulated in the step-cycle (Figs.8–10). The peak depolarization occurs at the transition from stance to swing. The oscillations in membrane potential are correlated with the activity profile of the extensor motoneurons and the common inhibitor 1 (Fig. 9). The described properties of interneuron type E4 in the actively behaving animal show that these interneurons are involved in the organization and coordination of the motor output of the proximal leg joints during reflex movements and during walking.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00192718
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  • 4
    Electronic Resource
    Electronic Resource
    Boekbespreking (1952)
    Springer
    De economist 100 (1952), S. 375-390 
    Details
    ISSN: 1572-9982
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02287639
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  • 5
    Electronic Resource
    Electronic Resource
    Mitochondrial DNA variation in social wasps (Hymenoptera, Vespidae) (1990)
    Springer
    Cellular and molecular life sciences 46 (1990), S. 1068-1072 
    Details
    ISSN: 1420-9071
    Keywords: Vespinae ; mitochondrial DNA ; restriction fragment length polymorphism (RFLP)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Patterns of restriction fragment length polymorphisms (RFLP) of European Vespinae were more similar within genera than between them. Distance trees were constructed that support the hypothesis of monophyly of the generaVespula andDolichovespula. Within the genusVespula, V. germanica was more closely related toV. rufa than toV. vulgaris. The position of the genusVespa remained uncertain due to the precision limits of the RFLP technique.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01940676
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  • 6
    Electronic Resource
    Electronic Resource
    The depressor trochanteris motoneurones and their role in the coxo-trochanteral feedback loop in the stick insect Carausius morosus (1986)
    Springer
    Biological cybernetics 55 (1986), S. 25-34 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract The innervation pattern of the coxal part of the depressor trochanteris muscle is described. This muscle is located inside the coxa cavity and is innervated by motoneurones contained in nerve C2. Serial sections of nerve C2 reveal that nerve C2 contains 3 large neurones (8, 5, and 3 μm in diameter) in addition to many small neurones. In extracellular nerve recordings from nerve C2 3 large spikes could be recorded, which can easily be classified according to their amplitudes. Combined intracellular muscle recordings and extracellular nerve recordings revealed the physiological characteristics of these motoneurones, which are referred to here as the “fast depressor trochanteris” (FDTr) motoneurone and the spontaneously active “slow depressor trochanteris” (SDTr) motoneurone. The third motoneurone could be identified as an inhibitory motoneurone. Because this motoneurone was also found in nerves nl2, nl3, nl5 and in nerve C1 (to the levator trochanteris muscle) it is referred to here as the “common inhibitor” (CI) motoneurone. The hypothesis that the trochanteral hairplate (trHP) is the only effective feedback transducer for the coxo-trochanteral control loop (Schmitz 1984, 1986) is confirmed by the nerve recordings from nerve C2, because no reflex response was measured after ablation of the trHP. In addition, shaving the trHP reduces the activity of the spontaneously active SDTr motoneurone. The frequency responses of the excitatory depressor motoneurones show that the spontaneous activity of the SDTr motoneurone is modulated by the stimulus over a wide range of stimulus frequencies up to 100 Hz and that the FDTr motoneurone is reflexly activated during the same phase of the stimulus as the SDTr motoneurone. Up to 20 Hz the maximum of the motoneurone activity leads the maximum of the movement by about 60 to 80 deg. This shows that nonlinear highpass filter properties of the coxotrochanteral control system, described on the basis of force measurements in an earlier paper (Schmitz 1986), can be found already on the level of the motoneurones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00363975
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  • 7
    Electronic Resource
    Electronic Resource
    Properties of the feedback system controlling the coxa-trochanter joint in the stick insect Carausius morosus (1986)
    Springer
    Biological cybernetics 55 (1986), S. 35-42 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract The angle of the coxa-trochanter (C-T) joint in the stick insect Carausius morosus is controlled by a negative feedback mechanism. It is shown that the trochanteral hair plate alone functions as the feedback transducer and that the rhomboid hair plate is not involved in the feedback loop. The properties of the C-T control system were investigated by means of force measurements. The results cannot be adequately described in all details by either a fractional differentiator model, a model which fits many sensory systems, or a nonlinear bandpass filter, a model which fits the force response of the femur-tibia feedback loop. The fractional differentiator model adequately describes the frequency response of the open-loop system to sinusoidal stimulation with 34 deg stimulus amplitude. However, the responses to sinusoidal and steplike stimulation with 10 deg stimulus amplitude do not fit this model. They are better described by the model of a nonlinear bandpass filter. The possible contribution of mechanical properties of the musculature and the joint to the total force response is discussed. It is suggested that cocontractions occurring at higher stimulus frequencies alters the muscle properties and enables the animal to respond to stimulus frequencies above the upper corner frequency of the active feedback loop.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00363976
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  • 8
    Electronic Resource
    Electronic Resource
    Central projections of leg sense organs inCarausius morosus (Insecta, Phasmida) (1991)
    Springer
    Zoomorphology 111 (1991), S. 19-33 
    Details
    ISSN: 1432-234X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The present study describes the central projections of leg proprioceptors important in resistance reflexes and in the control of leg movement in the stick insect. The following proprioceptors were studied: the femoral chordotonal organ and the campaniform sensilla on the proximal femur, the hair plate, the hair field and three groups of campaniform sensilla on the trochanter, and the two hair plates and four hair rows on the coxa. For comparison, single tactile hairs on the sternum, coxa, trochanter, and femur were also investigated. Afferent fibers were backfilled with cobalt and the central projections were studied in wholemounts and in sections. Results are compared with those from other insects and arthropods. Results for all three thoracic ganglia are similar. Projections of all the proprioceptors are confined to the ipsilateral half of the segmental ganglion. They all terminate in four common target areas — two each in the lateral and in the intermediate part of the hemiganglion. The two lateral areas lie rostrally and caudally in dorsal neuropile occupied by motoneuron processes. The two intermediate areas lie rostrally and caudally in midventral neuropile lateral to the ventral intermediate tract (VIT). These intermediate areas include part of the ventral coarse-grained neuropile (vcN). Target areas of different proprioceptors overlap considerably, but the intermediate projections of the campaniform sensilla lie slightly closer together than those of the other organs. In addition to these four areas, the afferent fibers of the femoral chordotonal organ (fCO) project to two medial target areas extending into neuropile medial to the VIT. Afferent fibers from the various sense organs reach these common target areas using different pathways, but these pathways share some common elements. Afferent fibers from one organ can follow several alternative pathways to the common target areas. The intermediate areas are reached by projections which form a rostral and a caudal prong extending medially in midventral neuropile. Fibers enter these rostral and caudal prongs either along the lateral margin of the ganglion (a path referred to as a lateral longitudinal bundle) or by crossing from one to the other through coarse-grained neuropile occupying the central core of each hemiganglion (a path referred to as an intermediate longitudinal bundle). Collaterals entering the dorsolateral target areas rise either directly along the margin of the neuropile or from the intermediate longitudinal bundle. The medial target areas of the fCO projections are reached by a third branch which proceeds from the margin of the ganglion medioventrally between the anterior and posterior prongs and then bifurcates. Fibers from different organs follow different routes to reach common target areas. In addition, fibers from the same organ vary in their distribution among alternative pathways. Projections from tactile hairs on the sternum, coxa, trochanter, and femur are quite different from those of the proprioceptive hairs. They proceed medially along the ventral margin of the ganglion to terminate in a loose plexus within medial parts of the ventral association center.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01632707
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  • 9
    Electronic Resource
    Electronic Resource
    Untersuchungen zum Einfluß von Defekten auf die Resonanzfrequenz bei Holz (1998)
    Springer
    Holz als Roh- und Werkstoff 56 (1998), S. 124-124 
    Details
    ISSN: 1436-736X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001070050281
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  • 10
    Electronic Resource
    Electronic Resource
    In vivo expression of a full-length cDNA copy of potato leafroll virus (PLRV) in protoplasts and transgenic plants (1997)
    Springer
    Molecular genetics and genomics 253 (1997), S. 609-614 
    Details
    ISSN: 1617-4623
    Keywords: Key words Potato leafroll virus  ;  Replication  ;  Solanum tuberosum  ;  Transgenic plants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A full-length cDNA copy (PLRVfl) of potato leafroll virus (PLRV) was constructed and examined in vivo for its biological activities by transient expression experiments with plasmid DNA or in vitro transcribed RNA. In addition, PLRVfl cDNA was stably introduced into the genome of potato plants by Agrobacterium-mediated leaf disc transformation. Both transient and stable expression of PLRVfl resulted in the synthesis of genomic and subgenomic PLRV RNAs. Transgenic plants accumulated the 17-kDa movement protein and displayed the typical symptoms of PLRV infection. This is the first example of the constitutive expression of a phloem-limited virus in planta.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004380050363
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