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  • Cell & Developmental Biology  (2)
  • Life and Medical Sciences  (2)
  • 12.38.Qk Experimental tests  (1)
  • 1
    ISSN: 1434-601X
    Schlagwort(e): 12.38.Qk Experimental tests ; 13.40.-f Electromagnetic processes and properties ; 13.60.Le Meson production
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract. An experiment on the radiative π{+}-meson photoproduction from the proton ( γp → γπ{+}n) was carried out at the Mainz Microtron MAMI in the kinematic region 537MeV 〈 Eγ 〈 817MeV, 140°≤ $ \theta_{{\gamma \gamma ^{\prime }}}^{{{{\rm cm}}}}$ ≤180°. The π{+}-meson polarizabilities have been determined from a comparison of the data with the predictions of two different theoretical models, the first one being based on an effective pole model with pseudoscalar coupling while the second one is based on diagrams describing both resonant and nonresonant contributions. The validity of the models has been verified by comparing the predictions with the present experimental data in the kinematic region where the pion polarizability contribution is negligible ( s1 〈 5mπ2) and where the difference between the predictions of the two models does not exceed 3%. In the region, where the pion polarizability contribution is substantial ( 5 〈 s1/mπ2 〈 15, -12 〈 t/mπ2 〈 - 2), the difference $\ensuremath{(\alpha -\beta )_{\pi^{+}}}$ of the electric (α) and the magnetic (β) polarizabilities has been determined. As a result we find $\ensuremath{(\alpha -\beta )_{\pi^{+}}=(11.6\pm 1.5_{{\rm stat}}\pm 3.0_{{\rm syst}}\pm 0.5_{{\rm mod}})\times 10^{-4}{}{\rm fm^{3}}}$ . This result is at variance with recent calculations in the framework of chiral perturbation theory.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 180 (1984), S. 81-103 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The distribution of the ganglia and nerves of the stomatogastric nervous system and the innervation of the extrinsic and intrinsic muscles are described. Median unpaired frontal and hypocerebral ganglia and paired ingluvial ganglia are present. The anterior pharynx is innervated by branches of the frontal nerve and by the anterior and posterior pharyngeal nerves, originating from the frontal ganglion. The posterior pharyngeal nerves are linked to nerves innervating the posterior part of the pharynx which have their origin in the hypocerebral ganglion, the anterior portion of which has previously been regarded as part of the recurrent nerve. Paired esophageal nerves run the length of the esophagus and crop between the hypocerebral and and ingluvial ganglia, innervating the muscularis by serial side branches. From each ingluvial ganglion runs an ingluvial nerve which innervates the gizzard and a cecal nerve which innervates the midgut and its ceca. At the posterior end of the midgut there is a poorly developed nerve ring. Nerves running posteriorly from this nerve ring link the stomatogastric nervous system with the proctodeal innervation from the terminal abdominal ganglion.Multipolar peripheral neurons are present on the muscularis of the whole of the foregut, rather randomly distributed on the crop and gizzard but forming fairly definite groupings at some points on the pharynx. Though of varied appearance, these cells could not be divided into discrete morphological categories. Peripheral neurons on the midgut are of different and characteristic morphology, though a few cells of the same appearance as those of the foregut occur at the midgut-hindgut boundary. Nerve fibers on the gut almost invariably terminate on the fibers of the muscularis.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 180 (1984), S. 105-124 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The anatomy of neurons of the stomatogastric nervous system of Ascheta domesticus was studied using heavy metal iontophoresis through cut nerve ends followed by silver intensification. Nineteen categories of neuron are described and compared with neurons known from the stomatogastric nervous system of other insects. Possible functions for the neurons are suggested. Motor neuron candidates are suggested for all parts of the gut served by the stomatogastric nervous system, and axons of sensory neurons of the anterior pharynx are located. There are four neuron types that cannot readily be assigned motor, sensory, or interneuron functions: large dorsal cells of the frontal ganglion; the two neurons of the nervus connectivus, and two categories of neurons in the median neurosecretory cell group of the pars intercerebralis, the axons of which are contained in the stomatogastric nerves.
    Zusätzliches Material: 18 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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