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  • 1
    Electronic Resource
    Electronic Resource
    β-decay half-lives of very neutron-rich isotopes of elements from Ti to Ni (1998)
    Springer
    The European physical journal 1 (1998), S. 275-283 
    Details
    ISSN: 1434-601X
    Keywords: PACS:23.40.-s β decay, double β decay, electron and muon capture – 27.30.+t 20 ≤ A ≤ 38 – 27.50.+e 59 ≤ A ≤ 89
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: The unknown β-decay half-lives of 22 isotopes far off stability (5 〈 T Z 〈 10) in the region from Ti to Ni were measured at GSI, Darmstadt. The nuclei were produced in a fragmentation reaction of 500 A.MeV 86Kr-projectile impinging on a thick Be target. The isotopes of interest were separated and identified with the fragment separator, FRS, by a combination of Bρ,Z, and ToF techniques. An additional range separation was performed by a selective implantation into granular detectors. The spatial and time correlations of the implant with the consecutively detected β-particles were used to determine the unknown half-lives. For nuclei far off stability, β-decay chains were measured and analyzed as well, leading to an even more reliable evaluation of the lifetimes. The large discrepancies found between the measured and the theoretical values emphasize that most recent theoretical work is not an improvement over calculations made almost a decade ago.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100500050062
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  • 2
    Electronic Resource
    Electronic Resource
    Production of medium-weight isotopes by fragmentation in 750 A MeV 238U on 208Pb collisions (1998)
    Springer
    The European physical journal 2 (1998), S. 193-198 
    Details
    ISSN: 1434-601X
    Keywords: PACS:25.75.-q – 25.70.Mn – 21.10.Ft – 21.10.Gv – 27.50.+e – 27.50.+j – 24.10.Pa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: Projectile fragmentation of 238U in a lead target was investigated at a bombarding energy of 750 A MeV. Isotopic production cross sections of about 250 different projectile fragments in the element range Z= 30–53 were measured with the FRagment Separator (FRS). The magnetic selection and the kinematical analysis of the measured isotopes allowed to disentangle fission and fragmentation residues. The mass loss of these residues indicates a violent collision where a large amount of energy is dissipated. The position of the fragmentation corridor defined by the measured residues was used to determine an effective proton-evaporation barrier.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100500050108
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  • 3
    Electronic Resource
    Electronic Resource
    Fission of highly excited fragments from collisions of 750 A.MeV 238U-ions on 208Pb (1998)
    Springer
    The European physical journal 2 (1998), S. 179-191 
    Details
    ISSN: 1434-601X
    Keywords: PACS:25.85.-w Fission reactions – 25.75.-q Relativistic heavy-ion collosions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: Fragments of relativistic 750 A.MeV U-projectiles were investigated by using the fragment separator FRS for magnetic selection of reaction products including ray-tracing and ΔE-ToF techniques. For elements between Ge and Sb, measurements of isotopic yield distributions and velocities revealed three processes: fragmentation, low-energy fission, and high-energy fission. The last of these regimes is presently reported. First and second moments of distributions of mass numbers, atomic numbers and velocities of the corresponding fragments allowed us to identify 101 43Tc56 as the most probable fragment of a high energy symmetric fission reaction. Moreover, we could deduce a hypothetical mean fissioning fragmentation product 208Rn and its highly excited pre-fragmentation parent 227Ra produced in a primary abrasion reaction at an excitation energy of about 290 MeV.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100500050107
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  • 4
    Electronic Resource
    Electronic Resource
    Total charge-changing cross sections for neutron-deficient isotopes from58Ni fragmentation (1995)
    Springer
    The European physical journal 352 (1995), S. 69-75 
    Details
    ISSN: 1434-601X
    Keywords: 21.10.Ft ; 25.70.Np ; 27.40.+Z
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract At the projectile-fragment separator FRS of GSI, relativistic secondary beams of about 520 MeV/nucleon were produced by fragmentation of a primary beam of58Ni at 650 MeV/nucleon in a beryllium target. By means of aΔE—Bρ—TOF measurement, the fragments have been identified and their charge-changing probabilities in targets of CH2, C, Al, and Pb have been determined. We describe the results for the total charge-changing cross sections in this first paper, whereas a second article deals with the partial charge-changing cross sections. At the drip line, the measured charge-changing cross sections exhaust close to 100% of the total interaction cross sections as calculated with semiempirical models. The measurements at the proton drip line with low-Z targets indicate that only a very small increase of the cross sections may be observed, whereas the measurements with a lead target show that no significant increase of the total charge-changing cross sections is present which would be a hint for low-lying dipole strength. Our experimental data are compared to Glauber-type calculations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01292761
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  • 5
    Electronic Resource
    Electronic Resource
    Few-neutron removal from238U at relativistic energies (1995)
    Springer
    The European physical journal 352 (1995), S. 163-169 
    Details
    ISSN: 1434-601X
    Keywords: 24.30.Cz ; 25.75.+r
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract As part of a comprehensive study of uranium fragmentation at relativistic energies at the GSI projectile fragment separator, FRS, inclusive neutron-removal cross sections have been measured for severalxn channels at projectile energies of 600 and 950A MeV using targets of Al, Cu and Pb. The variation of the experimental cross sections with target nuclear charge is used to disentangle nuclear and electromagnetic contributions. The electromagnetic cross sections agree surprisingly well with a simple harmonic oscillator calculation of giant dipole resonances based on measured photonuclear cross sections and do not require an extra enhancement of the two-phonon giant dipole excitation as concluded from similar measurements with197Au.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01298903
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  • 6
    Electronic Resource
    Electronic Resource
    Production and identification of heavy Ni isotopes: evidence for the doubly magic nucleus 28 78 Ni (1995)
    Springer
    The European physical journal 352 (1995), S. 351-352 
    Details
    ISSN: 1434-601X
    Keywords: 21.60.C5 ; 27.50+e ; 25.85-w
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We report the first observation of the doubly magic nucleus78Ni50 and the heavy isotopes77Ni,73,74,75Co,80Cu. The isotopes were produced by nuclear fission in collisions of 750 A·MeV projectiles of238U on Be target nuclei. The fully-stripped fission products were separated in-flight by the fragment separator FRS and identified event-by-event by measuring the magnetic rigidity, the trajectory, the energy deposit, and the time of flight. Production cross-sections and fission yields for the new Ni-isotopes are given.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01299748
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  • 7
    Electronic Resource
    Electronic Resource
    Exploring the Conformational Behavior of Rigid Porphyrin-Quinone Systems by High-Temperature MD Simulations and Temperature-Dependent 1H-NMR Experiments (1996)
    Springer
    Journal of molecular modeling 2 (1996), S. 383-385 
    Details
    ISSN: 0948-5023
    Keywords: High-Temperature MD Simulations ; Confor-mational Analysis ; Porphyrin-Quinone Systems ; Photosynthesis Models
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Photoinduced electron transfer reactions play an important role in the primary step of the biological photosynthesis process. In an attempt to understand better the mechanism of the charge separation organic donor-acceptor molecules containing porphyrins and quinones were designed as photosynthesis models. In order to study the structure dependence of the photoinduced electron transfer twofold and fourfold bridged porphyrin-quinone systems with increasing donor-acceptor distance were synthesized (Figure 1) [1, 2, 3]. It was assumed that in these molecules the porphyrin and quinone should be linked in a rigid and well-defined orientation. To verify this assumption the conformational behavior of these systems was studied by high-temperature MD simulations in combination with conformational analysis of selected minimized structures [4, 5].
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s0089460020383
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  • 8
    Electronic Resource
    Electronic Resource
    Serotonerge Dysfunktion als Folge sozialer Isolation Bedeutung für die Entstehung von Aggression und Alkoholabhängigkeit (1999)
    Springer
    Der Nervenarzt 70 (1999), S. 780-789 
    Details
    ISSN: 1433-0407
    Keywords: Schlüsselwörter Serotonin ; Verhaltensinhibierendes System ; Impulsivität ; Aggression ; Depression ; Key words Serotonin ; Behavior inhibition system ; impulsivity ; Aggression ; Depression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Dysfunction of serotonergic neurotransmission has been associated with two different psychopathological syndromes – impulsive aggressivity resulting form a lack of stimulation of the “behavior inhibition system” on the one hand and the manifestation of clinical depression and compulsive syndromes on the other. The examination of primate behavior provides a model which may reconciliate these seemingly contradictory hypotheses. According to primate experiments, monoaminergic depletion results in anxious and desperate behavior only if the individual has previously been exposed to social isolation stress, which in turn induces a decrease in the central serotonin turnover rate. Young non-human primates who experience early social separation stress are anxious and fearful, while as adults they tend to be aggressive, consume excessive amounts of alcohol and are less intoxicated by alcohol intake. These observation indicate the importance of social separation stress in the pathogenesis of alcoholism and antisocial behavior and may point to prophylactic and pharmacological treatment strategies.
    Notes: Zusammenfassung Eine Dysfunktion serotonerger Transmission wurde mit zwei verschiedenen psychopathologischen Syndromen in Verbindung gebracht. Einerseits wurde der serotonergen Neurotransmission eine wesentliche Rolle in der Stimulation des “verhaltensinhibierenden Systems” zuerkannt und postuliert, daß ein verminderter Serotoninumsatz zur Enthemmung impulsiver und aggressiver Verhaltensweisen führt. Andererseits gibt es Hinweise auf die Bedeutung einer verminderten serotonergen Transmission in der Pathogenese der Depression und der Angsterkrankungen. Eine mögliche Deutung der vordergründig widersprüchlichen Befunde ergibt sich aus der Untersuchung serotonerger Transmission bei Primaten. Eine pharmakogen induzierte Verarmung an monoaminergen Neurotransmittern führt demnach nur dann zu depressionsanalogen Verhaltensweisen, wenn in der individuellen Entwicklung mehrfach Phasen sozialer Isolation durchlebt wurden. Umgekehrt ist soziale Isolation bei jungen Primaten mit einem verminderten Serotoninumsatz, verstärkter Ängstlichkeit und sozialer Inkompetenz assoziiert, während sich bei diesen Primaten im Erwachsenenalter eine erhöhte Aggressivität und Alkoholtoleranz und ein erhöhter freiwilliger Alkoholkonsum nachweisen lassen. Diese Befunde unterstreichen die Bedeutung von Streß- und Lernfaktoren in der Ausgestaltung der psychopathologischen Korrelate einer serotonergen Dysfunktion und verweisen auf mögliche prophylaktische und pharmakologische Behandlungsoptionen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001150050512
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  • 9
    Electronic Resource
    Electronic Resource
    Anhedonie – nosologieübergreifendes Korrelat einer Dysfunktion des dopaminergen Verstärkungssystems? (1999)
    Springer
    Der Nervenarzt 70 (1999), S. 391-398 
    Details
    ISSN: 1433-0407
    Keywords: Schlüsselwörter Anhedonie ; Dopaminerges Verstärkungssystem ; Negativsymptomatik ; „Incentive salience” ; Stimulus-induzierte Dopaminfreisetzung ; Key words Anhedonia ; Dopaminergic reward system ; Negative symptoms ; Incentive salience ; Stimulus-induced dopamine release
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary The dopaminergic reward system is activated by primary rewarding factors such as food, sexual activity and parental care. Its activation enhences the occurency of behaviors which induced the stimulation of dopaminergic neurotransmission. Indications of a dysfunction of the dopaminergic reward system are found in major depression, schizophrenia, and addictive disorders. It has been hypothesized that dysfunction of the dopaminergic reward system is associated with anhedonia, the inability to experience pleasure. However, animal studies indicate that a reduction of central dopaminergic neurotransission is associated with a de- crease in incentive salience of reward-indi-cating stimuli and not with anhedonia per se. Sensitization of dopaminergic neurotransmission, on the other hand, seems to induce cue-dependent craving in addicted patients. In schizophrenia, phasic, stimulus-dependent dopamine release in the striatum may play a role in the abnormal attribution of salience to previously neutral stimuli.
    Notes: Zusammenfassung Das dopaminerge Verstärkungssystem wird durch sog. primäre Verstärker wie Essen, sexuelle Aktivität und elterliches Fürsorgeverhalten angesprochen. Seine Aktivierung führt zum gehäuften Auftreten all jener Verhaltensweisen, die zu seiner Stimulation beigetragen haben. Hinweise auf Störungen zentraler dopaminerger Transmission finden sich bei so unterschiedlichen Krankheitsbildern wie der majoren Depression, der Schizophrenie und bei Abhängigkeitserkrankungen. Damit stellt sich die Frage, ob Anhedonie, der „Verlust der Lebensfreude”, als nosologieübergreifendes Korrelat einer Dysfunktion des dopaminergen Verstärkungssystems auftritt. In Tierversuchen ergaben sich Hinweise darauf, daß eine verminderte dopaminerge Neurotransmission mit einer reduzierten Aufmerksamkeitszuwendung gegenüber belohnungsanzeigenden Stimuli und nicht mit Anhedonie per se assoziiert ist. Demgegenüber induziert eine Sensitivierung des dopaminergen Systems bei Abhängigkeitserkrankungen möglicherweise das stimulus-abhängige Verlangen nach der Suchtsubstanz. Eine Enthemmung der phasischen, stimulus-induzierten Dopaminfreisetzung im Striatum könnte auch in der Pathogenese der Schizophrenie von Bedeutung sein und dazu führen, daß bislang neutralen Stimuli eine besondere Bedeutung zugeschrieben wird.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001150050454
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  • 10
    Electronic Resource
    Electronic Resource
    Psychopathologische Korrelate dopaminerger Dysfunktion bei alkoholabhängigen und schizophrenen Patienten (1999)
    Springer
    Der Nervenarzt 70 (1999), S. 399-407 
    Details
    ISSN: 1433-0407
    Keywords: Schlüsselwörter Dopaminerges Verstärkungssystem ; Anhedonie ; Alkoholabhängigkeit ; Dopaminhypothese der Schizophrenien ; Phasische versus tonische Dopaminfreisetzung ; Key words Dopaminergic reward system ; Anhedonia ; Alcohol dependence ; Dopamine hypothesis of schizophrenia ; Phasic versus tonic dopamine release
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary It has been suggested that anhedonia, the loss of pleasure, is associated with a dysfunction of the dopaminergic reward system in schizophrenic and alcohol-dependent patients. In a series of neuroendocrinological and brain imaging studies, we examined pre- and postsynaptic mechanisms of dopaminergic neurotransmission in non-human primates and in schizophrenic and alcohol-dependent patients. Among alcoholics, we found indicators of a sensitization of dopaminergic neurotransmission, which was associated with the relapse risk, but not with anhedonia or depression. Schizophrenics with neuroleptic blockade of striatal dopamine D2 receptors displayed psychomotor slowing and reduced motivation, but not anhedonia. Primate studies pointed to the importance of a temporo-cortical dysfunction in the pathogenesis of phasic dopaminergic dysregulation in the striatum. These observations indicate that a dysfunction of stimulus-dependent dopamine release may be associated with motivational deficits caused by a reduction in incentive salience, but not with anhedonia.
    Notes: Zusammenfassung Aufgrund von Tierversuchen war postuliert worden, daß Anhedonie das gemeinsame psychopathologische Korrelat einer Störung des dopaminergen Verstärkungssystems darstellt. In einer Serie neuroendokrinologischer und bildgebender Studien untersuchten wir prä- und postsynaptische Mechanismen der dopaminergen Neurotransmission bei Primaten sowie bei schizophrenen und alkoholabhängigen Patienten. Bei abstinenten alkoholabhängigen Patienten fanden sich Hinweise auf eine Sensitivierung der dopaminergen Neurotransmission, die mit dem Rückfallrisiko, nicht jedoch mit Anhedonie oder Depressivität assoziiert war. Schizophrene Patienten mit neuroleptikainduzierter Blockade der striären Dopamin-D2-Rezeptoren zeigten eine Motivationsstörung und psychomotorische Verlangsamung gegenüber medikationsfreien Patienten, aber keine Assoziation der Rezeptorblockade mit Anhedonie. Primatenstudien verwiesen auf die Rolle der temporofrontalen Kortices bei der Regulation der phasischen subkortikalen Dopaminfreisetzung. Unsere Befunde sprechen für die Annahme, daß eine Dysfunktion der stimulusabhängigen, striären Dopaminfreisetzung mit Motivationsstörungen, nicht jedoch mit Anhedonie, assoziiert ist.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001150050455
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