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  • 1
    Electronic Resource
    Electronic Resource
    Photoemission of spinpolarized electrons from strained GaAsP (1996)
    Springer
    Applied physics 63 (1996), S. 203-206 
    Details
    ISSN: 1432-0630
    Keywords: 79.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Strained layer GaAs.95P.05 photo cathodes are presented, which emit electron beams spinpolarized to a degree of P = 75% typically. Quantum yields around QE = 0.4% are observed routinely. The figure of merit P2 × QE = 2.3 × 10−3 is comparable to that of the best strained layer cathodes reported in literature. The optimum wavelength of irradiating light around 830 nm is in convenient reach of Ti:sapphire lasers or diode lasers respectively. The cathodes are produced using MOCVD-techniques. A GaAs.55P.45-GaAs.85P.15 superlattice structure prevents the migration of dislocations from the substrate and bottom layers to the strained overlayer. The surface is protected by an arsenic layer so that no chemical cleaning is necessary before installation into vacuum. The source of polarized electrons attached to the Mainz race track microtron MAMI works with such cathodes now. More than 1000 hours beamtime have been performed successfully.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01567651
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  • 2
    Electronic Resource
    Electronic Resource
    New chest imaging techniques: a comparison of five analogue and digital methods (1992)
    Springer
    European radiology 2 (1992), S. 335-341 
    Details
    ISSN: 1432-1084
    Keywords: Radiography ; digital — Lung ; radiography — Images ; quality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In recent years new analogue and digital techniques have become available for chest imaging. This study compares conventional film/screen, asymmetric film/screen (InSight), equalization (Amber), storage phosphor and digital image intensifier techniques by phantom exposures and patient examinations. The quality of chest images of 43 patients was classified by seven observers in four different hospitals. According to the results of phantom measurements and a previous study, digital image intensifier radiography was excluded from the patient examinations because of its low image quality. The Amber system had the best image quality. Images of the storage phosphor system were of good quality in both mediastinal and peripheral fields of the chest. Compared to conventional film/screen, the asymmetric film/screen (InSight) was graded higher in the mediastinal field, but lower in the peripheral field.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00175438
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  • 3
    Electronic Resource
    Electronic Resource
    Isolation and biological activity of aspidospermine and quebrachamine from an Aspidosperma tree source
    Amsterdam : Elsevier
    Journal of Pharmaceutical and Biomedical Analysis 12 (1994), S. 1283-1287 
    Details
    ISSN: 0731-7085
    Keywords: Aspidospermine ; indoleolkaloids ; liquid chromatography. ; quebrachamine
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0731-7085(94)00066-2
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  • 4
    Electronic Resource
    Electronic Resource
    First measurement of the electric formfactor of the neutron in the exclusive quasielastic scattering of polarized electrons from polarized ^3He
    Amsterdam : Elsevier
    Physics Letters B 327 (1994), S. 201-207 
    Details
    ISSN: 0370-2693
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0370-2693(94)90718-8
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  • 5
    Electronic Resource
    Electronic Resource
    G-Proteins in alpha1-adrenoceptor mediated prostatic smooth muscle contraction (1994)
    Springer
    Urological research 22 (1994), S. 143-146 
    Details
    ISSN: 1434-0879
    Keywords: BPH ; α1-adrenoreceptor ; pertussis toxin ; G-proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The role of signal transducing guanine-nucleotide binding proteins (G-proteins) in α1-receptor mediated smooth muscle contractions was investigated in human hyperplastic prostatic tissue. The selective α1-receptor agonist phenylephrine (PE) evoked dose dependent contractions antagonized by the α1-receptor blockers prazosin (EC50 10 nM) and YM 617 (EC50 3 nM). Application of nifedipine (1–10,000 nM), a blocker of voltage-dependentl-type Ca2--channels (VDCC), inhibited the PE evoked contraction up to 65.4%. Pretreating the tissue strips with pertussis toxin (PTX, exotoxin from Bordetella pertussis; 5–25 μg/ml), inactivating a subpopulation of G-proteins, inhibited the PE induced contractions up to 73.9%. PTX pretreatment had no effect on contractions elicited by 125 mMK-. Application of nifedipine to PTX pretreated tissue led to an additional inhibition of 13.7%. Our findings demonstrate the involvement of PTX-sensitive G-proteins in the signal transduction pathway of α1-receptor induced contractions of prostatic smooth muscle. The remaining contractility of PTX pretreated tissue suggests additional participation of PTX insensitive mechanisms in α1-receptor mediated prostatic smooth muscle contractions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00571840
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  • 6
    Electronic Resource
    Electronic Resource
    Variable effects of iodinated contrast media on different rabbit arteries in vitro (1997)
    Springer
    Urological research 25 (1997), S. S21 
    Details
    ISSN: 1434-0879
    Keywords: Iodinated contrast media ; Diatrizoate ; Iohexol ; Isolated arteries ; Organ bath Vasoconstriction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Vasoconstriction caused by iodinated contrast media (CM) has been considered specific for the renal artery only. We examined the vascular effect of CM in rabbit carotid, aorta, renal, iliac, mesenteric and celiac arteries and found that other arteries also respond with a contraction to CM. Isolated arterial rings were exposed to diatrizoate (high osmolar CM), iohexol (low osmolar CM) or glucose solution, and the isometric contraction response was expressed as percentage of an initial KCl control contraction. Diatrizoate evoked contractions of 82% (carotid), 63% (aorta), 30% (renal), 24% (iliac), 28% (mesenteric) and 18% (celiac), respectively. Iohexol caused contractions of 31% (carotid), 24% (aorta), 15% (renal) and 14% (iliac), whereas the mesenteric and celiac arteries were relaxed by iohexol. A high osmolar glucose solution elicited contractions of 78%, 77%,11%, 27%, 3% and 5%, respectively, in the arteries. CM have contraction potency in arterial vasculature other than the renal artery.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00942043
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  • 7
    Electronic Resource
    Electronic Resource
    Role of intracellular Ca2+ stores in smooth muscle contractions of the guinea pig vas deferens (1993)
    Springer
    Urological research 21 (1993), S. 319-323 
    Details
    ISSN: 1434-0879
    Keywords: α1-adrenoceptor ; Benign prostatic hyperplasia ; Ca2+ channels ; Intracellular Ca2+ stores ; Vas deferens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Guinea pig vas deferens was used as an animal model for alpha-1 adrenoceptor (α1-receptor) mediated contractions in human hyperplastic prostatic tissue. The selective α1-receptor agonist, phenylephrine (PE), induced fully reversible, dose-dependent contractions antagonized by increasing concentrations of the α1-receptor blockers prazosin (1–100 nM) and YM 617 (0.1–10 nM). Removal of extracellular Ca2+ reduced PE-evoked contractions in a time-dependent manner. Nifedipine (1–1000 nM), a blocker of voltage-dependent L-type Ca2+ channels (VDCC), inhibited the PE-induced response by up to 65%. Removal of extracellular Ca2+ abolished the α1-agonist reactivity in a time-dependent fashion. To elucidate the participation of intracellular Ca2+ stores in α1-receptor contractions, the tissue was pretreated with ryanodine (10 μM) or thapsigargin (0.1 μM), established inhibitors of Ca2+ release from intracellular pools. Both substances reduced the PE contractions by up to 80%. Nifedipine suppressed the remaining contractions completely. This provides evidence that Ca2+ influx through VDCC and Ca2+ release from intracellular stores contribute to α1-receptor contractions in the guinea pig vas deferens and may be important in obstructive benign prostatic hyperplasia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296828
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  • 8
    Electronic Resource
    Electronic Resource
    Ryanodine-sensitive intracellular Ca2+ stores in isolated rabbit penile erectile tissue (1995)
    Springer
    Urological research 22 (1995), S. 393-398 
    Details
    ISSN: 1434-0879
    Keywords: Penile erection ; Smooth muscle ; Calcium channel blocker ; Intracellular calcium ; Ryanodine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Norepinephrine release from adrenergic nerve terminals leads to a rise in intracellular Ca2+, which promotes penile smooth muscle contraction and detumescence. Ca2+ sources are the extracellular space and sarcoplasmic Ca2+ stores. To elucidate the role of intracellular stores strips from rabbit erectile tissue were investigated in an organ bath study. Contractions were elicited by phenylephrine (PE) and electrical stimulation. Incubation in Ca2+-free solution as well as exposure to nifedipine did not abolish electrical or PE-induced contraction. Ryanocline (10-5 mol/l), a functional blocker of sarcoplasmic Ca2+ channels, significantly reduced PE response. In the presence of caffeine (10-3 mol/l) the effect was significantly enhanced. Addition of nifedipine nearly abolished the contraction. These results provide evidence for intracellular Ca2+ pools in cavernosal tissue and indicate that the α1-adrenoceptor-induced contraction requires the opening of voltage-gated Ca2+ channels and the release of Ca2+ from intracellular stores.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296883
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  • 9
    Electronic Resource
    Electronic Resource
    Comparative regulation of α1-adrenergic receptor mediated contraction in urogenitally derived smooth muscle (1997)
    Springer
    Urological research 25 (1997), S. S13 
    Details
    ISSN: 1434-0879
    Keywords: Smooth muscle tone ; EGF ; α 1-Adrenoceptor-mediated contraction ; Benign prostatic hyperplasia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Contractility of smooth muscle within mammalian urogenital organ systems has an established role in physiological/pathophysiological functioning of the component structures. Our aim was to examine the direct effect of epidermal growth factor (EGF) on smooth muscle tone as well as its indirect effects in regulatingα 1-adrenoceptor-mediated contraction of the prostate, the vas deferens and renal arteries. Tissues were mounted isometrically, under controlled conditions, and changes in tension in response to treatment with phenylephrine (PE) with or without pretreatment with EGF were recorded on a physiological recorder via force transducers. In the rabbit prostate, EGF potentiated the magnitude of contraction to PE. The potentiation appeared to be dependent on cyclo-oxygenase products. In the human prostate, EGF potentiated the contractile response to PE. EGF had no effect on the PE-induced contraction of the rabbit renal artery and vas deferens. EGF alone did not alter smooth muscle tone in any of the above-mentioned tissues. The main finding of this study is the difference in the regulation by EGF of theα 1-adrenoceptor-mediated response in smooth muscle of the prostate, from that by the vas deferens and renal artery. The reasons for this difference in response remain to be elucidated. This study may form the basis for further investigation into receptor transregulation and its relevance to symptomatic benign prostatic hyperplasia (BPH).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00942042
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  • 10
    Electronic Resource
    Electronic Resource
    First measurement of the polarisation transfer on the proton in the reactions $$H(\vec e,e'\vec p)$$ and $$D(\vec e,e'\vec p)$$ (1995)
    Springer
    The European physical journal 352 (1995), S. 211-214 
    Details
    ISSN: 1434-601X
    Keywords: 13.40.Fn ; 25.30.Bf
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The measurement of the polarisation transfer to the proton in the reactions $$H(\vec e,e'\vec p)$$ and $$D(\vec e,e'\vec p)$$ performed with longitudinally polarised electrons in quasi-free kinematics is presented. The coincidence measurement was executed atQ 2≈8fm −2 using the 855 MeV, c.w. beam of the Mainz Microtron MAMI. The recoil polarisation was determined by means of a carbon analyser. The experiment shows that the binding of the nucleon does not modify the polarisationP x of the recoil proton within an error ofΔ P x/Px≈10%. The measured polarisation agrees with recent theoretical predictions. Implications for the measurement of the electric form factor of the neutron using the $$D(\vec e,e'\vec n)$$ reaction are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01298910
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