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  • 1
    Electronic Resource
    Electronic Resource
    Current-induced coupling between conductance channels in membranes (1980)
    Springer
    The European physical journal 37 (1980), S. 249-264 
    Details
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The driven system of conducting channels in a nerve membrane is investigated. A current flow generates a coupling between the channels: the current through a channel is influenced by the presence of other conducting channels via the deformation of the equipotential surfaces within the media adjacent to the membrane. We derive an integral equation for the membrane voltageV(s) (s in the membrane plane) and solve it for different membrane conductance distributionsγ(s) including models for stochastic distributions of conducting channels.V(s) is a nonlinear functional ofγ(s). The system of coupled channels is compared with an Ising model. The system exhibits a multi-channel interaction which can be characterized by two different rangesd int andD 1. For a mean channel distanced 0≫d int interaction effects are negligible, and ford 0≪D 1 all channel-voltages are equal and thus represent a “mean-field” for the channels. Increasing conductivity of the medium decreasesd int and increasesD 1. With experimental data on sodium channels in nerve membranes we find:d int≈d 0, i.e. a 50% decrease of the channel-voltages by the interaction, andD 1≈103⋯104 d 0, which indicates mean-field behaviour of the channels. In a subsequent paper we shall treat the statistics of channels which open and close stochastically under the influence of the local membrane voltage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01323039
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  • 2
    Electronic Resource
    Electronic Resource
    Statistical model of current-coupled ion channels in nerve membranes (1981)
    Springer
    The European physical journal 41 (1981), S. 153-164 
    Details
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A statistical model of a driven system is developed. Its microscopic elements are the ion channels through a nerve membrane. Their conductances are stochastically switching under the competing influences of thermal noise and local membrane voltage. A current flow through the membrane induces a coupling between the channels via the electrolytes surrounding the membrane. The long range of the coupling permits a generalized mean field theory for the stationary membrane current as a function of the applied electrode voltage. We derive analytically the macroscopic conductance-voltage-temperature relation for the spatially uniform current state. It shows analogues of first and second order phase transitions. The critical temperature diverges at a finite coupling strength. The theory fits sodium conductance characteristics measured on nerve axon membranes from various species by a variation of only the coupling strength. This supports the hypothesis that this simplest possible model for sodium channels is universal for all species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01293414
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  • 3
    Electronic Resource
    Electronic Resource
    Untersuchungen an Diazoverbindungen und Aziden, XLII. (Diazomethyl)cyclopropene durch elektrophile Diazoalkan-substitution (1982)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 2965-2980 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Investigations on Diazo Compounds and Azides, XLII. (Diazomethyl)cyclopropenes by Electrophilic Diazoalkane SubstitutionThe (diazomethyl)cyclopropenes 9 and 10 are formed via electrophilic diazoalkane substitution preferably of diazomethylphosphoryl compounds with cyclopropenylium salts. Either the diazomethyl compounds (7a-c) react with the cyclopropenylium salts 6a-e in the presence of triethylamine (method A) or the metallated diazo compounds 8a-d are combined with the cyclopropenylium bromides 6c-e (method B) (details see table 1). The (diazomethyl)cyclopropenes undergo a novel type of isomerization to pyridazines, partly without heating (9d-f → 11b-d), partly by refluxing in toluene (9a,g → 11a,e as well as 10e,f → 12a,b). The bicyclic betaines 15 and 17 are supposed to be intermediates. The diazomethyl compounds 9a and b yield the α,β- unsaturated ketones 20a and b by acid-catalyzed decomposition.
    Notes: Die (Diazomethyl)cyclopropene 9 und 10 entstehen durch elektrophile Substitution vorzugsweise von Diazomethylphosphorylverbindungen mit Cyclopropenyliumsalzen. Man setzt entweder die Diazomethylverbindungen selbst (7a-c) in Gegenwart von Triethylamin mit den Cyclopropenyliumsalzen 6a-e um (Methode A) oder läßt die metallierten Diazoverbindungen 8a-d mit den Cyclopropenyliumbromiden 6c-e reagieren (Methode B) (Details s. Tab. 1). Die (Diazomethyl)-cyclopropene gehen teils ohne Erwärmen (9d-f → 11b-d), teils beim Erhitzen in Toluol (9a,g → 11a,e sowie 10e,f → 12a,b) eine neuartige Isomerisierung zu Pyridazinen ein; Zwischenstufen sind vermutlich die bicyclischen Betaine 15 und 17. Die Diazomethylverbindungen 9a und b liefern bei der säurekatalysierten Zersetzung die α,β-ungesättigten Ketone 20a und b.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19821150904
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  • 4
    Electronic Resource
    Electronic Resource
    Neuronal plasticity in the afferent visual system (1975)
    Springer
    Psychological research 38 (1975), S. 147-174 
    Details
    ISSN: 1430-2772
    Source: Springer Online Journal Archives 1860-2000
    Topics: Psychology
    Notes: Summary The susceptability to, plastic changes of single units along the afferent visual pathway (optic tract/OT/, dorsal lateral geniculate body /LGB/) was investigated by means of classical conditioning procedures. These consisted of pairing either two light stimuli in different parts of the receptive field or pairing a light-spot with a non-visual stimulus. OT and LGB units were classified into dominant tonic and phasic groups on the basis of their response pattern to illumination of the receptive field center. 1) No consistent, reproducible modification was found in OT units (either in the tonic or in the phasic group) and in most LGB units with dominant tonic discharge pattern. 2) One-third of phasic LGB units (11% of the whole sample) with large, eccentric receptive fields exhibited consistent modifications of the response pattern during conditioning which persisted in some units for several minutes, in other units only for 20–30 seconds. 3) It has been suggested that the phasic (transient or Y-) system of the LGB incorporates plastic elements with a capability of short-term information storage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00308522
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  • 5
    Electronic Resource
    Electronic Resource
    Neuronal plasticity in the afferent visual system (1975)
    Springer
    Psychological research 38 (1975), S. 117-146 
    Details
    ISSN: 1430-2772
    Source: Springer Online Journal Archives 1860-2000
    Topics: Psychology
    Notes: Summary The effect of long lasting flicker stimulation on the excitatory responses of single units in the optic tract (OT), and the lateral geniculate body (LGB) of cat, was analysed with respect to changes in response strength. ON- and OFF-center units were stimulated with periodic light increments and decrements, respectively, in the receptive field center (RFC). OT units were classified into phasic and tonic, LGB units into phasic, tonic and intermediate, according to their response to a 500 msec stimulus. During the first 30 seconds of 1-Hz flicker stimulation, all OT units and over 90% of the LGB units exhibited a progressive decrease of their responses to roughly half the initial magnitude. The decay was significantly steeper in LGB units than in OT units. Trend analysis of the later responses (after 30 sec) revealed a further slow decrease in tonic LGB units, amounting to 20% in 10 minutes, but not in OT units. The recovery after 10 min of flicker stimulation took about 2–5 min. No systematic difference in the time course of responses was found between ON- and OFF-center units and between the phasic and tonic OT units. Part of the phasic and intermediate LGB units (about 20% of all LGB units) behaved differently in terms of fast habituation of a response component. The influence of intensity, frequency, and mode (increment or decrement) of stimulation was studied, leading to the conclusion that changes in light adaptation alone cannot account for the findings. The stronger decay of LGB units relative to the OT output is discussed either on the basis of passive, intrinsic geniculate processes (tonic units), or in terms of active, acculumating hyperpolarizing activity (phasic and intermediate units).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00308521
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  • 6
    Electronic Resource
    Electronic Resource
    Disparity sensitivity and receptive field incongruity of units in the cat striate cortex (1978)
    Springer
    Experimental brain research 31 (1978), S. 523-545 
    Details
    ISSN: 1432-1106
    Keywords: Visual cortex ; Binocular cells ; Stereoscopic mechanism ; Eye movement correction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Receptive field correspondence and binocular interaction were studied in the cat striate cortex using fundus photography for correction of residual eye drifts. 2. The scatter of incongruities (frequently called receptive field disparities) was found to be equal in horizontal and vertical direction (S.D. 0.5 °, N = 96). Incongruity was not correlated with field orientation. 3. Using binocular stimulation, disparity tuning and binocular facilitation were analysed quantitatively in 46 cells. Seven of these were disparity specific, i.e. showed marked facilitation critically dependent on disparity. 4. With monocular stimulation, three of the seven disparity specific cells could be driven only from one eye; one gave weak responses to both left and right monocular stimulation, and one no monocular responses at all. 5. The disparity specific cells preferred vertical or oblique orientations, and vertical disparity was less critical than horizontal disparity. The disparity tuning curves, plotted with reference to the experimentally determined horopter, showed peaks within 0.5 ° crossed and 0.2 ° uncrossed disparity. The smallest half-widths at half-amplitude were 0.25 °. Some of the curves were asymmetric, or step-like, with a steep slope at zero disparity. 6. It is concluded that stereoscopic depth may be signalled by disparity specific cells in area 17. These cells could account for stereoscopic acuity of a few min arc, if one assumes that depth is encoded in the amount of activity of single units, or in the graded imbalance of activity of antagonistic units. 7. It is argued that the distribution of incongruities does not reflect stereoscopic function because the disparity specific cells often cannot be plotted in both eyes, and most of the units that can be plotted are not disparity selective.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00239810
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  • 7
    Electronic Resource
    Electronic Resource
    Optical near-field excitation at the semiconductor band edge: Field distributions, anisotropic transitions and quadrupole enhancement (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 112 (2000), S. 7831-7838 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The optical near-field response of a three dimensional subwavelength aperture-semiconductor system is analyzed within a finite difference time domain scheme for Maxwell's and excitonic material equations. The analysis includes the field modification due to the high refractive index environment and the excitonic response to a near-field distribution. The resonant optical response is illustrated for anisotropic dipole transitions in quantum wells and the enhancement of the quadrupole transition in materials with dipole forbidden interband transitions. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.481387
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  • 8
    Electronic Resource
    Electronic Resource
    Synthesis and evaluation of mono-, di-, and trifluoroethenyl-GABA derivatives as GABA-T inhibitors (1987)
    s.l. : American Chemical Society
    Journal of medicinal chemistry 30 (1987), S. 267-272 
    Details
    ISSN: 1520-4804
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/jm00385a007
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  • 9
    Electronic Resource
    Electronic Resource
    An unfortunate book tour (2006)
    [s.l.] : Nature Publishing Group
    Nature 444 (2006), S. 400-400 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Johnny Morton stood in the trapezoid silhouette of the New York Public Library. Four marble statues of literary figures guarded the entryway under an awning propped up by gleaming black columns. Clarke, Wells, Verne, Bulgakov, all gazing westward across the plaza and beyond. Above this was the ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/444400a
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  • 10
    Electronic Resource
    Electronic Resource
    Jung and Religion (1977)
    Oxford, UK : Blackwell Publishing
    The @journal of analytical psychology 22 (1977), S. 0 
    Details
    ISSN: 1468-5922
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Psychology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1465-5922.1977.00175.x
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