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  • 1
    Electronic Resource
    Electronic Resource
    A neural model of the dynamic activation of memory (1993)
    Springer
    Biological cybernetics 68 (1993), S. 455-463 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract We study an Attractor Neural Network that stores natural concepts, organized in semantic classes. The concepts are represented by distributed patterns over a space of attributes, and are related by both semantic and episodic associations. While semantic relations are expressed through an hierarchical coding over the attribute space, episodic links are realized via specific synaptic projections. Due to dynamic thresholds expressing neuronal fatigue, the network's behavior is characterized by convergence toward the concept patterns on a short time scale, and by transitions between the various patterns on a longer time scale. In its baseline, undamaged state, the network manifests semantic, episodic, and random transitions, and demonstrates the phenomen of priming. Modeling possible pathological changes, we have found that increasing the ‘noise’ level or the rate of neuronal fatigue decreases the frequency of semantic transitions. When neurons characterized by large synaptic connectivity are deleted, semantic transitions decay before the episodic ones, in accordance with the findings in patients with Alzheimer's disease.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00198778
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  • 2
    Electronic Resource
    Electronic Resource
    Time behavior of topological ordering in self-organizing feature mapping (1997)
    Springer
    Biological cybernetics 77 (1997), S. 419-427 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract. The dynamics of the feature maps created by Kohonen's algorithm is studied by analyzing the wave number and frequency-dependent spectral density of synaptic fluctuations. This so-called dynamical spectral density, which is well known in nonequilibrium statistical physics, constitutes a complete record of the time and length scales involved in the evolution of the map, the pertinent information being of much practical interest for the study of the convergence properties and the design of effective parameter cooling strategies. We derive explicit theoretical expressions for the dynamical spectral density based on the Fokker-Planck description of the stochastic process of learning and study in some detail the folding phenomena observed in the feature map as a consequence of a dimensional conflict between input and output space. By comparisons with extensive numerical simulations the Fokker-Planck picture is found to describe both the space and the time behavior of the map very well as soon as the dimensional conflict is well below a certain critical value. Results for the time and length scales involved in the evolution of the map are given both below and above the critical value of the dimensional conflict. Moreover exploiting a certain analogy of the feature map with an elastic net we propose a new quantitative criterion measuring the topographic (neighborhood preserving) properties of the map in terms of the spectral density of the elastic tensions in the net. By way of examples we demonstrate how topological defects such as twists and kinks lead to characteristic elastic tensions that are revealed immediately by the spectral analysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004220050401
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  • 3
    Electronic Resource
    Electronic Resource
    Quinidine-digoxin interaction: Evidence for involvement of an extrarenal mechanism (1982)
    Springer
    European journal of clinical pharmacology 21 (1982), S. 281-285 
    Details
    ISSN: 1432-1041
    Keywords: quinidine ; digoxin ; anuria ; haemodialysis ; serum digoxin ; plasma quinidine ; protein binding ; extrarenal digoxin clearance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The influence of quinidine 750 mg per day for one week on serum digoxin concentration (SDC) was evaluated in digitalized anuric patients on chronic haemodialysis. During quinidine administration the SDC increased markedly, from 0.84±0.37 to 1.58±0.72 ng/ml (p〈0.01), a comparable effect to that reported previously in patients with normal renal function. Neither in vitro nor in vivo did quinidine alter the serum protein binding of digoxin. The increase in SDC in anuric patients indicates a decrease in the extrarenal clearance of digoxin, which means that mechanisms other than of renal origin are also involved in the interaction of quinidine and digoxin. There was great interindividual variability in the extent of the quinidine-induced rise in SDC. Regardless of the state of renal function, careful monitoring of digitalized patients seems mandatory once quinidine treatment is initiated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00637614
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  • 4
    Electronic Resource
    Electronic Resource
    Proteins and glycoproteins of monkey and human platelets. Comparison by high resolution two-dimensional gel electrophoresis
    Amsterdam : Elsevier
    Comparative Biochemistry and Physiology -- Part B: Biochemistry and 74 (1983), S. 825-830 
    Details
    ISSN: 0305-0491
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0305-0491(83)90153-0
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  • 5
    Electronic Resource
    Electronic Resource
    -mesons in dense nuclear matter
    Amsterdam : Elsevier
    Nuclear Physics, Section A 545 (1992), S. 267-269 
    Details
    ISSN: 0375-9474
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0375-9474(92)90466-W
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  • 6
    Electronic Resource
    Electronic Resource
    Growth and characterization of Bi"2Sr"2CaCu"2O"8"+"δ and Bi"2Sr"2CuO"6"+"γ single crystals
    Amsterdam : Elsevier
    Physica C: Superconductivity and its applications 203 (1992), S. 180-192 
    Details
    ISSN: 0921-4534
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0921-4534(92)90525-H
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  • 7
    Electronic Resource
    Electronic Resource
    Variation of Seed Glucosinolates in Lines of Brassica napus (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Plant breeding 105 (1990), S. 0 
    Details
    ISSN: 1439-0523
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The glucosinolate (GSL) pattern of 93 resynthesized (resyn) repeseed lines was examined over three years, and five stable genotypes with distinct GSL profiles were identified. Typically the resyn B. napus profile exhibited progoitrin as the main GSL, but contained sinigrin. The different GSL patterns of the four deviating lines are discussed with respect to the proposed biosynthetic pathway. Within the resyn and further extensive breeding materias, screening for low indolyl GSL contents resulted in finding one genotype with an extremely low 4-hydroxy-gluco-brassicin and glucobrassicin content. Furthermore, other lines were identified, over a wide range of indolyl GSL contents. The values were stable over two years.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1439-0523.1990.tb00449.x
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  • 8
    Electronic Resource
    Electronic Resource
    Field and high-temperature dependence of the long term charge loss in erasable programmable read only memories: Measurements and modeling (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 4522-4540 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: High-temperature charge transport across an oxide-nitride-oxide sandwich of erasable programmable read only memories is mainly governed by the oxide conductivity as experimentally determined. It was verified in the examined devices that charge loss is not due to mobile ions. Since hole injection from the control gate into the nitride can be blocked by a 70-A(ring)-thick top oxide we conjecture that charge loss is due to leakage of electrons; however, the observed leakage current is too large to be explained by pure electrode-limited charge transport (Richardson emission and direct tunneling). It was also verified that field gain on asperities and along edges cannot increase the charge loss current to the required range. Numerical evaluation of trap tunneling and resonant tunneling indicated that both mechanisms are weakly temperature dependent while charge loss has a typical activation energy of 1.2 eV in the range of 250–350 °C. Consequently, a multiphonon-assisted tunneling mechanism is proposed where electrons stored on the floating gate tunnel to oxide traps, then are emitted into the nitride. The coupling of the trap level to oxide phonons results in virtual energy levels in the oxide which allow for more effective transition paths. As a consequence of the electron-phonon coupling, the emission occurs close to the oxide conduction-band edge at temperatures between 250 and 350 °C, producing a strong temperature dependence for the mechanism. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.359414
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  • 9
    Electronic Resource
    Electronic Resource
    Alpha particle losses from Tokamak Fusion Test Reactor deuterium–tritium plasmas (1996)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 3 (1996), S. 1875-1880 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Because alpha particle losses can have a significant influence on tokamak reactor viability, the loss of deuterium–tritium alpha particles from the Tokamak Fusion Test Reactor (TFTR) [K. M. McGuire et al., Phys. Plasmas 2, 2176 (1995)] has been measured under a wide range of conditions. In TFTR, first orbit loss and stochastic toroidal field ripple diffusion are always present. Other losses can arise due to magnetohydrodynamic instabilities or due to waves in the ion cyclotron range of frequencies. No alpha particle losses have yet been seen due to collective instabilities driven by alphas. Ion Bernstein waves can drive large losses of fast ions from TFTR, and details of those losses support one element of the alpha energy channeling scenario. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.871983
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  • 10
    Electronic Resource
    Electronic Resource
    Investigation of the influence of edge structure on the micromagnetic behavior of small magnetic elements (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 2994-2999 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Thin film elements of a soft magnetic nickel–iron alloy have been fabricated with structured edges in order to determine their effect on the magnetization reversal processes. Lorentz microscopy was used to study acicular elements with different edge structures and these were compared with standard elements with straight edges. The presence of the structured edges results in deviations of the magnetization along the length of the elements in the remanent state. Switching processes are described for a number of different elements and the effect of structuring the edges is discussed. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.372289
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