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  • 1
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Chromatography A 36 (1968), S. 120-123 
    ISSN: 0021-9673
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Chromatography A 64 (1972), S. 327-340 
    ISSN: 0021-9673
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0040-6090
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1351
    Keywords: Key words Olfaction ; Crustacea ; Sensory filters ; Electrophysiology ; Invertebrate ; AbbreviationsASW artificial sea water ; Hyp trans-4-hydroxy-l-proline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract To understand how chemoreceptor organs may extract temporal information from odor plumes, we investigated the frequency filter properties of lobster chemoreceptor cells. We used rapid stimulation and high-resolution stimulus measurement for accurate stimulus control and recorded extracellular responses from chemoreceptors in the lobster lateral antennule in situ. We tested 16 hydroxyproline-sensitive cells with a series of ten 100-ms pulses at 10, 100 and 1000 μmol l−1 at stimulation frequencies from 0.5 Hz to 4 Hz. Receptor cell responses could accurately encode 10 μmol l−1, but not 100 or 1000 μmol l−1 pulses, delivered at rates of 4 Hz. Flicker-fusion frequency and synchronization with the stimulus pulse train were concentration dependent: performance rates above 1 Hz became poorer both with increasing pulse amplitude and frequency. Flicker fusion frequency was 3 Hz for 100 μmol l−1 pulses and 2 Hz for 1000 μmol l−1 pulses. Individual cells showed differences in their stimulus pulse following capabilities, as measured by the synchronization coefficient. These individual differences may form a basis for coding temporal features of an odor plume in an across-fiber pattern.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-2021
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract Electrical conductivities of Ni2SiO4, Fe2SiO4, and MgSiO3 were measured on synthetic powders in the temperature range 340° to 1,100° C and at pressures up to 20 kbars. For ternary compounds such as olivines and pyroxenes the control of two further variables, like the chemical activities of two components are needed, besides temperature and pressure. The activities of the corresponding binary oxides were controlled by equilibrating the samples with their neighbour-phases. Control of the oxygen partial pressure was achieved by buffer techniques. From the slopes of the lg σ vs. 1/T lines the activation energies were calculated for 10 kbar: 0.56 eV and 2.7 eV for Ni2SiO4 in equilibrium with SiO2 and Ni/NiO-buffer for the temperature range 500°–800°C and 800°–1,000°C resp. 0.52 eV for Fe2SiO4 in equilibrium with SiO2 and metallic iron, and 0.38 eV in equilibrium with SiO2 and magnetite; 1.11 eV for MgSiO3 in equilibrium with SiO2, and 1.25 eV in equilibrium with Mg2SiO4.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 174 (1994), S. 803-811 
    ISSN: 1432-1351
    Keywords: Temporal filters ; Flicker fusion ; Stimulus measurement ; Lobster olfaction ; Crustacean
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract 1. We developed a high resolution, on-line stimulus measurement system for accurate control of chemical stimulus applications for Homarus americanus lateral antennule chemoreceptors. Focal stimulus presentations in an electrophysiological preparation with the receptor sensilla intact were measured at small spatial (30 μm) and time (5 ms) scales. 2. We tested 15 receptor cells with ten 100 ms pulses of 104 M hydroxyproline at 0.5, 1, 2 and 4 Hz and with a single 8 s square pulse. Individual cells showed differences in their capabilities to resolve pulses (“flicker fusion”). At 2 Hz stimulation, some cells could follow stimulus pulses while others could not. At 4 Hz, 3 cells could still encode individual stimulus pulses accurately. The population resolved pulses up to 2 Hz; at 4 Hz, the population response to a pulse series approximated the response to a square pulse. 3. Repetitive stimulation caused a gradual decrease in the number of spikes and a gradual increase in first spike latency (“cumulative adaptation”). Increased stimulation frequency resulted in greater cumulative adaptation. 4. Since individual differences in adaptation and disadaptation rates of the receptor cells could not be attributed to measured stimulus variability in situ, lobster chemoreceptor cell populations have intrinsic temporal diversity which, we hypothesize, could be used to analyze pulsatile stimuli that occur in natural turbulent odor plumes.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 172 (1993), S. 81-90 
    ISSN: 1432-1351
    Keywords: Spontaneous reactions ; Learning behaviour ; Chemosensory stimuli ; Goldfish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The present behavioural experimental paradigm made use of the responsiveness of goldfish to natural and non-familiar chemosensory stimuli in the context of feeding. With the exception of Tubifex food extract, which was spontaneously preferred, goldfish exhibited no spontaneously recordable response to low concentrations of the stimuli tested. Training experiments using non-familiar stimuli (amyl acetate, α-ionone, β-phenylethanol, 10-6, 10-7 M) required 2–3 months of daily training prior to the animals reaching a 70% positive response level for discrimination. This discrimination was dependent upon a functioning olfactory system as no responses were recorded after bilateral exclusion of olfaction, e.g. dissection of olfactory nerve or olfactory tracts. Amino acids (Ala, Arg, Gln, Gly, Lys), more natural stimuli than those listed above, were preferred when applied at concentrations 〈 10-5 M. Goldfish were able to discriminate amino acid odours applied at 10-6 or 10-7 M, but these stimuli elicited no spontaneous response below 10-5 M. Ten to twenty reinforcements were sufficient to achieve discrimination between amino acids, which again was eliminated after bilateral exclusion of olfactory pathways. In contrast to the 4-week period for long-term memory to non-familiar odours, long-term memory for amino acids lasted at least 3 months.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 175 (1994), S. 95-105 
    ISSN: 1432-1351
    Keywords: Chemoreceptor ; Response reliability ; Intensity coding ; Hydroxy-L-proline ; Lobster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract 1. To determine reliability of stimulus intensity coding we measured the response variability of 30 hydroxy-L-proline sensitive chemoreceptor cells from antennules of Homarus americanus. First, cells were tested with 5 repeated presentations of 10-5 M and l0-4 M hydroxy-L-proline. Then a stimulus response function was determined in each cell from l0-6to 5 × l0-4 M in half log steps. 2. Population mean responses to repetitive stimulation showed little variability and mean stimulus response functions increased monotonically. In contrast, most individual cells showed a high response variability and no single cell stimulus-response function increased monotonically. The greatest response variability occurred between different cells. 3. Mean response magnitude of a 30 cell population allowed reliable discrimination between 10-5 M and l0-4 M hydroxy-L-proline for each of the 5 repetitions. It also allowed discrimination of all concentrations of hydroxy-L-proline tested. Across-fiber response patterns also differed significantly with concentration while they remained relatively stable with repetition of the same stimulus. 4. We applied different analytical methods to test the reliability of response magnitude and across-fiber pattern as possible codes for intensity discrimination. We demonstrated that a random population of rather unreliable receptor cells could provide remarkably reliable intensity information to the CNS based on response magnitude or across-fiber pattern.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Naturwissenschaften 53 (1966), S. 506-506 
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Naturwissenschaften 46 (1959), S. 401-401 
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
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