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  • 1985-1989  (8)
  • Chemistry  (4)
  • Adaptation  (2)
  • GC-MS  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Neural correlates of motion after-effects in cat striate cortical neurones: monocular adaptation (1988)
    Springer
    Experimental brain research 72 (1988), S. 1-20 
    Details
    ISSN: 1432-1106
    Keywords: Vision ; Visual cortex ; Adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Motion after-effects were elicited from striate cortical cells in lightly-anaesthetized cats, by adapting with square-wave gratings or randomly textured fields drifting steadily and continuously in preferred or null directions. The time-course and recovery of responsiveness following adaptation were assessed with moving bars, gratings or textured fields. Results were compared with controls in which the adapting stimulus was replaced by a uniform field of identical mean luminance, and also assessed in relation to the strength and time course of adaptation. Within 30–60 s adaptation, firing declined to a steady-state. Induced after-effects were direction-specific, and manifest as a transitory depression in response to the direction of prior adaptation, recovering to control levels in 30–60 s. Maximal after effects were induced by gratings of optimal drift velocity and spatial frequency. With rare exceptions after-effects were restricted to driven activity; no consistent effects on resting discharge were observed. The onset of adaptation, and the recovery period, were more rapid in simple cells, although after effects of comparable strength were elicited from simple and from standard complex cells. Special complex cells, including many of the more profoundly texture-sensitive neurones in the cortex, were more resistant to adaptation. The results support the conclusion that psychophysically measured adaptation and induced motion after-effect phenomena reflect the known properties of cortical neurones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00248495
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    The pattern specificity of velocity aftereffects (1985)
    Springer
    Experimental brain research 60 (1985), S. 71-78 
    Details
    ISSN: 1432-1106
    Keywords: Motion ; Velocity ; Visual cortex ; Adaptation ; Texture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Interactions between two different visual patterns, a coarse grating and a fine texture pattern, were investigated in the context of velocity aftereffects in human subjects. The perceived velocity shift, in which the perceived velocity of a moving test pattern is reduced following exposure to a similarly moving adaptation pattern, is apparent when the adaptation and test patterns are of the same or different types. The aftereffect transfers interocularly in both cases. The directional tuning of the aftereffect is broad, and has a different profile for texture adaptation than for bar adaptation. When adaptation is to a composite stimulus comprising independently moving bars and texture, the aftereffect varies according to the nature of the test pattern. The results are discussed with reference to interactions between the responses of neurones in feline striate cortex to the two types of pattern.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237020
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Volatile components of scent material from cotton-top tamarin (Saguinus o. oedipus) (1988)
    Springer
    Journal of chemical ecology 14 (1988), S. 1367-1384 
    Details
    ISSN: 1573-1561
    Keywords: Primate ; callitrichids ; Saguinus o. oedipus ; chemical communication ; scent marking ; chemical analysis ; GC-MS ; volatile composition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The first chemical analysis of the volatile components of scent material from the cotton-top tamarin,Saguinus o. oedipus is presented. In contrast to our previous findings in saddle-back tamarins (Saguinus fuscicollis), the chemical composition of the scent marks is quite variable. Analysis of secretion expressed manually from different areas of the scent pads of sedated animals shows individual and regional variability. Only three components (squalene, cholesterol, andp-methoxybenzaldehyde) were found in all scent mark samples analyzed. However, suprapubic secretions obtained from one sedated female contained, in addition, 12 butyrate esters as well as five acetate esters which were homologous to the butyrates. The butyrate esters have been previously identified in scent material fromSaguinus fuscicollis. The variability of the composition of the scent material is discussed in relation to the scent-marking behavior of the cotton-top tamarins. Behavioral studies tested the ability of the cotton-top tamarins to discriminate between scent marks from conspecifics and scent marks from saddle-back tamarins. The group of 12 subjects discriminated between the scent marks from both species in choice tests during which they could freely contact the scent samples. However, when scent marks were presented under a screen, so that the subjects could smell but not contact the stimuli, no discrimination was shown. Four individuals displayed more interest in the screened scent stimuli than all other subjects. When these animals were tested in a second experiment for their ability to discriminate between material from the two species on the basis of only volatile cues, it became evident that they were able to do so. These results indicate that volatile cues alone enable the tamarins to recognize scent marks from conspecifics, but that additional cues perceived during contact with the scent are important for its full attractiveness and/or informational content.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01020141
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Analysis of chemical signals in a primate species (Saguinus fuscicollis): Use of behavioral, chemical, and pattern recognition methods (1986)
    Springer
    Journal of chemical ecology 12 (1986), S. 513-531 
    Details
    ISSN: 1573-1561
    Keywords: Chemical communication ; scent marking ; pattern recognition ; Saguinus fuscicollis ; GC-MS ; primate ; tamarin ; skin secretions ; n-butyrate esters ; concentration profiles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Scent marking with specialized skin glands is a common behavior in the tamarin,Saguinus fuscicollis. The scent marks identify species, subspecies, gender, and individual, and they also contain information on the social position and hormonal condition of an animal. The marks are chemically complex, containing a large number of compounds. Analysis by means of gas chromatography-mass spectrometry has identified 16 major components (squalene and 15 esters of butyric acid). These compounds are present in the marks of males and females of two subspecies,Saguinus f. fuscicollis andSaguinus f. illigeri. Application of computerized pattern recognition techniques has shown that concentration patterns of some of the butyrates are diagnostic of the two subspecies while concentration patterns of other butyrates are diagnostic of males and females regardless of subspecies. Behavioral studies have shown that the concentration patterns of butyrates and squalene alone do not encode information on subspecies and gender. It is, however, likely that this information is partially encoded by these specific butyrate-squalene concentration patterns but that yet unidentified compounds in the scent marks serve as necessary synergists.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01020570
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Pumping characteristics of self-wiping twin-screw extruders - A theoretical and experimental study on biopolymer extrusion (1989)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 29 (1989), S. 433-440 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The flow of Newtonian and non-Newtonian fluids which obeys a power law relationship between shear stress and shear rate has been modeled in the melt conveying section of a self-wiping co-rotating twin-screw extruder using a finite element analysis of an unwound channel section. Predictions of throughput against pressure gradient are compared with experimentally obtained results for maize grits which is represented as a power law material. Rheological data applicable to extrusion simulation were obtained from capillary rheometry. Comparisons are reasonable with predicted characteristic showing similar behavior.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760290702
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Pressure losses in the packing stage of injection molding (1986)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 26 (1986), S. 1282-1289 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The pressure loss between the mold and the nozzle in the injection molding of bar and box moldings has been monitored. The pressure drop observed during filling of the mold is reduced during the packing stage but remains finite. This has been attributed in the literature to solidification of polymer across the cavity transducer and to melt relaxation phenomena. Experiments have been carried out with hot molds to prolong the packing stage at the expense of the ‘cooling’ stage. Under these circumstances the pressure drop is reduced but not eliminated. The observed pressure drop may be related to the viscosity of the melt and its dependence on pressure and temperature although strain-induced crystallization and the pressure dependence of the melting point can confer effects similar to the cooling stage.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760261808
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Stable isotope ratio analysis of leucine and ketoisocaproic acid in blood plasma by gas chromatography/mass spectrometry. Use of tertiary butyldimethylsilyl derivatives (1988)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 2 (1988), S. 14-16 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290020105
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    Paper (German National Licenses)
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  • 8
    Electronic Resource
    Electronic Resource
    Some features of the injection molding of short fiber reinforced thermoplastics in center sprue-gated cavities (1987)
    Brookfield, Conn. : Wiley-Blackwell
    Polymer Composites 8 (1987), S. 16-21 
    Details
    ISSN: 0272-8397
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: This paper describes an investigation into the fiber orientation in a number of center sprue fed cavities in short glass fiber filled polypropylene and nylon. The data have been interpreted in terms of a generalized five-layer structure resulting from the frozen skin formation and the high and low shear levels in the flowing melt. The implications for scaling up the mold size are discussed from the results obtained with different shot volumes. The fiber structure was observed to depend on location in the molding, local injection time, and injection rate. In addition the occurrence of fiber-free layers within the moldings using the filled polypropylene increases with an increase in shot volume, which produces an inherent ‘scale-up’ problem. Notwithstanding the mold geometry subtleties, the fiber orientation in all the moldings follows similar patterns and trends.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pc.750080104
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