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  • 1
    Electronic Resource
    Electronic Resource
    Oxidative stress and neurodegenerative disorders (1998)
    Springer
    Journal of biomedical science 5 (1998), S. 401-414 
    Details
    ISSN: 1423-0127
    Keywords: Oxidative stress ; Reactive oxygen species ; Excitotoxicity ; Hydroxyl radical ; Peroxynitrite ; Antioxidants ; Polyphenols ; Neurodegenerative disorders ; Apoptosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Oxidative insults, whether over-excitation, excessive release of glutamate or ATP caused by stroke, ischemia or inflammation, exposure to ionizing radiation, heavy-metal ions or oxidized lipoproteins may initiate various signaling cascades leading to apoptotic cell death and neurodegenerative disorders. Among the various reactive oxygen species (ROS) generated in the living organism, hydroxyl and peroxynitrite are the most potent and can damage proteins, lipids and nucleic acids. It appears that some natural antioxidants (tocopherol, ascorbic acid and glutathione) and defense enzyme systems (superoxide dismutase, catalase and glutathione peroxidase) may provide some protection against oxidative damage. Recent findings indicate several polyphenols and antioxidant drugs (probucol, seligilline) are effective in protecting the cells from ROS attack. Further development of these antioxidant molecules may be of value in preventing the development of neurodegenerative diseases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02255928
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Theory of quantum dynamics in fermionic environment: An influence functional approach (1987)
    Springer
    Journal of statistical physics 47 (1987), S. 17-55 
    Details
    ISSN: 1572-9613
    Keywords: Path integral ; influence functional ; fermion bath ; real-time density matrix ; Grassmann algebra ; quantum Langevin equation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Quantum dynamics of a particle coupled to a fermionic environment is considered, with particular emphasis on the formulation of macroscopic quantum phenomena. The framework is based on a path integral formalism for the real-time density matrix. After integrating out of the fermion variables of the environment, we embed the whole environmental effects on the particle into the so-called influence functional in analogy to Feynman and Vernon's initial work. We then show that to the second order of the coupling constant, the exponent of the influence functional is in exact agreement with that due to a linear dissipative environment (boson bath). Having obtained this, we turn to a specific model in which the influence functional can be exactly evaluated in a long-time limit (long compared to the inverse of the cutoff frequency of the environmental spectrum). In this circumstance, we mainly address our attention to the quantum mechanical representation of the system-plus-environment from the known classical properties of the particle. It is shown that, in particular, the equivalence between the fermion bath and the boson bath is generally correct for a singlechannel coupling provided we make a simple mapping between the nonlinear interaction functions of the baths. Finally, generalizations of the model to more complicated situations are discussed and significant applications and connections to certain practically interesting problems are mentioned.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01009034
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    A new method for quantum processes in fermionic heat baths (1987)
    Springer
    Journal of statistical physics 49 (1987), S. 811-826 
    Details
    ISSN: 1572-9613
    Keywords: Adiabatic transformation ; fermion bath ; Grassmann algebra ; influence functional ; path integral ; real-time density matrix
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The general path-integral formalism for real-time dynamics for a quantum system in a fermionic environment proposed previously is investigated by using a new method called local adiabatic transformation. This method is based on the observation that in the long-time limit (the time scale of the system is much larger than that of the environment, typically characterized by the inverse of the cutoff frequency of the environment), most degrees of freedom of the environment will follow the dynamics adiabatically. This feature is utilized by transforming the original problem of coordinate coupling into a problem of velocity coupling. This is achieved by making some simple unitary transformation on the fermion field (before path-integrating out of that field). By doing perturbations on the new problem, all the previous important results are recovered. Further-more, generalizations to more realistic situations [for example, a particle traveling over a large distance and coupled to a Fermi gas through the phase factor exp(ik·R) (the coupling may involve many channels of angular momentum)] are considered and significant results obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01009357
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    Paper (German National Licenses)
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