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  • 1
    Electronic Resource
    Electronic Resource
    A submillimeter polychromator for plasma spectroscopy (1996)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 67 (1996), S. 3108-3116 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A 12-channel grating polychromator for the measurement of electron cyclotron emission on the Frascati tokamak upgrade (FTU) has been built. Three gratings can be exchanged remotely, to allow the instrument to cover three different spectral ranges (between 200 and 600 GHz) which correspond to the second harmonic of electron cyclotron emission for tokamak magnetic fields of 4, 6, and 8 T. Three sets of low-pass filters, whose cut-off frequencies are optimized for each grating, are used to cut the high diffraction orders. In order to exchange the filters together with the grating it was necessary to integrate the groups of filters with the polychromator itself. This has been done reducing the grating sizes and assembling them all closely on a moveable structure. The exchange of gratings and filters can be performed remotely via computer in few seconds without any lost of the alignment. InSb cryogenic hot-electron bolometers are used as detectors. The cryostat hold-time is more than 30 days. Spectral resolution λ/δλ is about 40 corresponding to a spatial resolution of δR≈2.3 cm. The minimum detectable temperature is about 10 eV at 20 kHz bandwidth. The spatial structure and temporal evolution of several kinds of fast temperature perturbations (as the ones due to magnetohydrodynamic activity, temperature fall during pellet injection and plasma disruption) have been measured on FTU by means of this diagnostic system. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1147436
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  • 2
    Electronic Resource
    Electronic Resource
    Long-term Potentiation of NMDA Receptor-mediated EPSP in Guinea-pig Hippocampal Slices (1991)
    Oxford, UK : Blackwell Publishing Ltd
    European journal of neuroscience 3 (1991), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Hippocampal slices from guinea-pigs were used to examine the long-term potentiation (LTP) of the N-methyl-D-aspartate (NMDA)-mediated excitatory postsynaptic potential (EPSP). lntracellular recordings were performed from CA1 pyramidal neurons in the presence of 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, 5–10 μM) and picrotoxin (50 μM). In these experimental conditions test stimuli applied at low frequency (0.1 Hz) to the Schaffer collateral - commissural pathway evoked a prolonged EPSP (150–200 ms). To obtain this CNQX-resistant EPSP, stimulus intensities had to be raised above the level required to evoke an EPSP of comparable amplitude in physiological solution. Tetanic stimulation (two trains of 100 Hz, 1 s every 20 s) led to a potentiation of the CNQX-resistant EPSP, and this potentiated response was abolished with d-(-)-2-amino-5-phosphonovaleric acid (50μM). The potentiation of the NMDA receptor-mediated EPSP was more pronounced for strong than for weak test stimuli, and was suppressed when test EPSPs were evoked during membrane hyperpolarization. These results suggest that NMDA receptor-mediated responses can undergo LTP, and hence can contribute to the maintenance of LTP.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-9568.1991.tb00096.x
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  • 3
    Electronic Resource
    Electronic Resource
    Ontogeny of queen attraction to workers in the antCataglyphis cursor (Hymenoptera: Formicidae) (1991)
    Springer
    Insectes sociaux 38 (1991), S. 293-305 
    Details
    ISSN: 1420-9098
    Keywords: Ontogeny ; Formicidae ; learning ; queen attractant cues ; queen recognition ; Cataglyphis cursor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The behaviour ofCataglyphis cursor workers towards queens at 15 days, one month or two months after worker emergence was tested. Workers reared entirely with their own maternal queen were tested with this queen or with an unfamiliar alien queen. Workers transferred within 48 h of emerging to a new definitive nest with an alien queen were tested with this queen or with the original maternal queen. The degree of attraction to each of these queens and the workers' behavioural repertoire were measured and analysed. The results showed the following: 1) The attractiveness of queens and the workers' queen recognition behaviour were linked. 2) Although unfamiliar alien queens hardly attract workers, familiar alien queens were as attractive as maternal queens, and induced the same strongly marked and unique worker response, indicating that workers learn queen attractant cues in the days immediately after emergence. 3) Agonistic reactions were observed, but workers continued to be attracted to their maternal queen even after developing an attraction response to an alien queen with which they had been reared. These results agree with the proposal that queens produce two kinds of pheromones, those that attract workers and those that mediate recognition of queens by workers. These results show the ability of workers to discriminate between queens. Workers are attracted to any queen, but recognize as nestmates only maternal or alien queens with which they have been maintained. 4) The differential in worker attraction and recognition from 15 days to 2 months and its modifications by post-imaginal experience illustrate worker behavioural ontogeny, which is a basis of social discrimination.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01314915
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of dopamine, D-1 and D-2 dopaminergic agonists on the excitability of hippocampal CA1 pyramidal cells in guinea pig (1990)
    Springer
    Experimental brain research 83 (1990), S. 124-130 
    Details
    ISSN: 1432-1106
    Keywords: Dopamine ; D-1 and D-2 agonists ; Afterhyperpolarization ; Hippocampal slices ; Guinea pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In hippocampal pyramidal cells (HPCs), Dopamine (DA) application (1 μM) produced, in 50% of recorded cells, an hyperpolarization of the resting membrane potential (r.m.p.) and an increase of the afterhyperpolarization (AHP) amplitude and duration in 79% of recorded cells. DA-induced effects on both the r.m.p. and AHP were mimicked by bath application of a D-l selective agonist, SKF 38393 (20 μM). In addition, we have observed that a D-l selective antagonist such as SCH 23390 (1 μ,M) abolished the action of both DA and SKF 38393. In contrast, the activation of D-2 receptors through LY 171555 (10 μm) produced, in 50% of cells, a depolarization of the r.m.p. and a depression of the AHP in 67% of recorded cells. These results suggest that the effects observed in hippocampal pyramidal neurons after DA application of micromolar concentration are mediated by D-1 subtype of receptors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00232200
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  • 5
    Electronic Resource
    Electronic Resource
    Epileptiform activity in rat hippocampal slices isolated after local septal lesioning by ibotenic acid (1991)
    Springer
    Neurophysiology 23 (1991), S. 410-416 
    Details
    ISSN: 1573-9007
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In surviving slices of rat hippocampus, isolated from 1 to 4 weeks after septal lesioning by ibotenic acid, extracellular and intracellular responses were recorded in region CA3. Spontaneous and evoked epileptiform focal discharges are described, synchronous with paroxysmal depolarization shifts (PDS) of the membrane potential and with burst activity of cells. It is shown that the development of synchronized population reactions and PDS have an "all or nothing" character. The values of the resting potential and input resistance of the neurons did not differ significantly from those of cells in the control group of slices. Histological analysis showed destruction of neurons in the dorsal part of the septum, with cells of the medial septum being unaffected. The role of intraseptal mechanisms in the generation of epileptiform activity in region CA3 of hippocampal slices is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01052445
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  • 6
    Electronic Resource
    Electronic Resource
    Change in neuronal excitability in hippocampal sections of rats isolated after the destruction of the medial septal area (1992)
    Springer
    Neuroscience and behavioral physiology 22 (1992), S. 39-44 
    Details
    ISSN: 1573-899X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The influence of chronic destruction of the medial septal area (MSA) on focal potentials (FP) of field CA 1 evoked by stimulation of Schaffer collaterals was studied in experiments on viable sections of the the hippocampus of rats. The preparation, incubation, and pickup of FP of the sections of the control and experimental groups were carried out in identical conditions using traditional methods. The amplitude-temporal of population EPSP and population spikes, their interdependance, and their dependance on the strength of the stimulating current were assessed using automated data analysis. It was demonstrated that coagulation of the MSA is accompanied by an increase in the excitability of neuronal complexes of the lateral portion of field CA 1 which is manifested by the generation of multiple rhythmic discharges and the development of spike activity of the cells at a lower intensity of the synoptic inflow. It is hypothesized that destruction of the MSA leads to a relative attenuation of inhibitory control in the neuronal systems of field CA 1,the elements of which are depolarized with anomalous synchronicity and generate rhythmic impulse trains.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01186666
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