Bibliothek

feed icon rss

Ihre E-Mail wurde erfolgreich gesendet. Bitte prüfen Sie Ihren Maileingang.

Leider ist ein Fehler beim E-Mail-Versand aufgetreten. Bitte versuchen Sie es erneut.

Vorgang fortführen?

Exportieren
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 337 (1990), S. 451-463 
    ISSN: 1434-601X
    Schlagwort(e): 13.30.Eg ; 12.40.Aa ; 14.20.Gk
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Within the framework of the constituent quark model we discuss the effects of different types of meson-baryon-baryon vertex operators on the form factors and the coupling strengths of the lowest-lying positive and negative parity non-strange baryons. We compare the quark pair creation model (3P0-model) with the SU(6)-model in which mesons are treated as elementary fields that directly couple to the quarks. The latter model is employed both in the so-called static limit and in a modification motivated by Galilei invariance. It is demonstrated that the inclusion of non-static effects simulates some features of the3P0 vertex. Especially the reaction πN→ππN is found to be very sensitive to the different assumptions on the dynamics of theq¯q pair creation process. More indirect hints for the internal structure of the mesons might be obtained from the predicted asymmetry for the two form factors ofN→Δ+π andΔ→N+π, which occurs in the3P0-model, only.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 2
    ISSN: 1435-1463
    Schlagwort(e): Positron emission tomography ; (18F)methylspiperone ; clozapine ; haloperidol ; D2 dopamine receptors ; schizophrenia
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Four schizophrenic patients were investigated with dynamic positron emission tomography (PET) using (18F)fluorodeoxyglucose (FDG) and (18F)methylspiperone (MSP) as tracers. Two schizophrenics were on haloperidol therapy at the time of MSP PET. The other two schizophrenics were treated with clozapine, in one of them MSP PET was carried out twice with different daily doses (100 mg and 450 mg respectively). Neuroleptic serum levels were measured in all patients. Results were compared with MSP PET of two drug-free male control subjects and with a previous fluoroethylspiperone (FESP) study of normals. Three hours after tracer injection specific binding of MSP was observed in the striatum in all cases. The striatum to cerebellum ratio was used to estimate the degree of neuroleptic-caused striatal D2 dopamine receptor occupancy. In the haloperidol treated patients MSP binding was significantly decreased, whereas in the clozapine treated patients striatum to cerebellum ratio was normal. Even the increase of clozapine dose in the same patient had no influence on this ratio. Despite the smaller number of patients the study shows for the first time in humans that striatal MSP binding reflects the different D2 dopamine receptor affinities of clozapine and haloperidol.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 3
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 326 (1987), S. 413-420 
    ISSN: 1434-601X
    Schlagwort(e): 12.40.Qq ; 13.30.Eg ; 14.20.−c
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Within the framework of the non-relativistic quark model (NRQM) we discuss the influence of the coupling between baryonic excitations and meson fields. This leads to the interpretation of the baryon resonances as bound (q)3-configurations embedded in the corresponding meson-baryon continua. This concept is formulated analytically and applied to the description of the low-lying (N=0)- and (N=1)-multiplets with strangeness (S=0) and (S=−1). It turns out that the effects of this coupling are comparable in size to the effects induced by the hyperfine interaction. In particular, a remarkable cancellation of the spin-orbit forces of theqq-interaction and the meson-baryon interaction is observed. The implications of the strong baryon-meson coupling on the baryon-baryon interaction and on the formulation of the Hamiltonian for a multibaryon system are briefly discussed.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
Schließen ⊗
Diese Webseite nutzt Cookies und das Analyse-Tool Matomo. Weitere Informationen finden Sie hier...