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  • 1
    Electronic Resource
    Electronic Resource
    The wind-orientation of walking carrion beetles (1989)
    Springer
    Journal of comparative physiology 164 (1989), S. 775-786 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The wind-orientation of carrion beetles (Necrophorus humator F.) was studied by use of a locomotion-compensator. 1. Beetles walking on a horizontal surface for periods of several minutes in a dark environment without an air current and other orientational stimuli seldom keep straight paths. They walk along individually different circular paths (Fig. 1). The mean walking speed is 5.6±1.0 cm/s. The mean of the angular velocity reaches maximally 25 °/s for individual beetles (mean angular velocity of the analysed population of 152 beetles: 1.9±9.3 °/s). The distribution of the mean walking directions of the population shows that the beetles display no preference for one direction (Fig. 3 A). The instantaneous value of the individual angular velocity is independent of the instantaneous walking direction. 2. During exposure to an air current the individual beetles keep straight and stable courses with any orientation relative to the direction of air flow (Fig. 4). The mean walking directions of 76 individuals point in all directions but there is a weak preference of windward tracks (Fig. 3B). 3. Wind orientated walking starts at a threshold wind velocity of about 5 cm/s (Fig. 6). The walking tracks straighten with increasing air current velocity. This leads to a narrowing of the distribution of the instantaneous walking directions around the preferred walking direction (Fig. 7C). This narrowing is due to an increase in the slope of the characteristic curve (angular velocity as a function of walking direction) of the wind-orientation system. 4. Twenty percent of the beetles show a spontaneous change of their anemotactic course during walks of 5 min duration. Neither the time of the change, its position on the track or the direction of the new course are predictable. There is, however, a slight preference for 90±20° changes in the walking direction (Fig. 8). 5. The antennae (Fig. 9) act as the only sense organs responsible for the wind orientation. The capability for wind orientated walks is lost after ablation of both flagella (Fig. 10).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00616749
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  • 2
    Electronic Resource
    Electronic Resource
    Aerodynamic and mechanical properties of the antennae as air-current sense organs inLocusta migratoria (1980)
    Springer
    Journal of comparative physiology 139 (1980), S. 357-366 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. The antennae of locusts (Locusta migratoria) project forward during flight, thus exposing the flagella to frontal air currents (Fig. 1). Aerodynamic forces (drag) acting on the flagella generate a torque (T) in the joint between the proximal flagellar segment and pedicel (where mechanoreceptors involved in flight control are located). The torque which is produced by pressure and frictional forces of the air during flight (Fig. 4) is related to air speed (V A ;T =b ·V A 1.44; Figs. 5 and 6) and to antennal angle (γ;T betweenT∼ sin2γ andT∼ Sin γ; Fig. 2). The aerodynamic properties of an antenna-shaped glass rod (Fig. 3) are similar to those of flagella: the drag coefficients of both decrease with increasing Reynolds number (Fig. 7). 2. Torque in the pedicellar-flagellar joint produces a deviation (β) which is a function of air speed (Figs. 10, 11 and 12). In flying locusts, bothT (Fig. 9) and β (Fig. 12) are opposed by active forward movements of the flagellum, arising from the antennal-positioning reaction (Figs. 1 and 8). β does not exceed the linear range of the mechanical characteristic of the pedicellar-flagellar joint (Fig. 13) and is less than 1 ° (Fig. 12). 3. The mechanical-directional characteristic of the antenna is asymmetric, i.e., the absolute value of the passive antennal deflection (ω) depends on the direction in which the flagellum is bent (Fig. 14). Forces of the same magnitude cause greater deflections (ω) forward than backward. However, the pedicellar-flagellar joint possesses a lower resistance to a backward bending, which is the effect of air currents during flight.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00610466
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  • 3
    Electronic Resource
    Electronic Resource
    The phasic influence of self-generated air current modulations on the locust flight motor (1983)
    Springer
    Journal of comparative physiology 150 (1983), S. 427-438 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. Using high speed film analysis (500 frames/s) to investigate the head nodding movement during tethered flight inLocusta shows that the position of the wind-sensitive head hairs with respect to the flight direction is altered by 5.5° in the rhythm of the wing beat (Fig. 2). 2. Wind measurements in the region of the hair fields demonstrate that the wind reaching the hairs during flight is modulated by the animal's own wing beat. The modulation has a peak-to-peak value of 0.6–1.0 m/s (Fig. 3). 3. An airstream with its speed modulated by these values was used to stimulate the wind-sensitive hairs to analyse the steady-state response during tethered flight in animals with the antennae removed (Fig. 1). In these entrainment experiments absolute coordination (a relation of locked phase) between the wind modulation and the flight oscillator is found in a range of about 3 Hz around the intrinsic flight frequency. At frequencies both above and below this range, relative coordination (a relation of preferred phase) is obtained (Figs. 4–7). 4. The dynamic response to step changes in the modulation frequency was tested. There is an immediate reaction, but it takes several wing beats to reach the new steady-state (Fig. 8). 5. When flight was elicited while a modulated wind stream was already blowing, the first wing beat occurred in a preferred phase with respect to the stimulus modulation (Figs. 10 and 11). 6. To understand the generation of the flight pattern, the whole flight oscillator must be considered as a cooperative system of central neuronal, sensory (proprioceptive) and mechanical components (Fig. 12).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00609569
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  • 4
    Electronic Resource
    Electronic Resource
    Travelling air vortex rings as potential communication signals in a cricket (1987)
    Springer
    Journal of comparative physiology 160 (1987), S. 79-88 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. Crickets of the non-stridulating speciesPhaeophilacris spectrum (Phalangopsidae) generate travelling air vortex rings, which might serve as a hitherto unknown method of non-acoustic communication involving air particle movements. 2. The males produce a series of forward wing flicks during courtship and single wing flicks during aggressive encounters (Figs. 1, 2). In simulation experiments with moving wing pairs (Fig. 3) travelling vortex rings were visualized by using TiCl4 smoke or tracer particles in the air flow field (Fig. 4). 3. The vortex rings have an initial diameter of about 2 cm, increasing to 5 cm, and travel a maximum distance of 15 cm, depending on wing size and wing flick duration. Both wing size and flick duration determine the Reynolds number (Fig. 6). 4. Generally the velocity of propagation of vortex rings (from an initial velocity of about 40 cm/s) decays exponentially with distance (Fig. 5B). 5. The internal structure of the vortex rings, as visualized with tracer particles (Fig. 8), reveals a typical rotational velocity field. Particle velocities approach 15 cm/s (Fig. 9). 6. The physical basis of vortex ring generation by wing flicks and their possible communication role are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00613443
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  • 5
    Electronic Resource
    Electronic Resource
    The course control system of beetles walking in an air-current field (1991)
    Springer
    Journal of comparative physiology 169 (1991), S. 671-683 
    Details
    ISSN: 1432-1351
    Keywords: Anemotaxis ; Carrion beetles ; Course control ; Menotaxis ; Necrophorus humator ; Wind-orientation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The wind-orientated walk of carrion beetles Necrophorus humator F. was analysed under closed-loop conditions with a walking compensator and under openloop conditions with a paired tread wheel (Fig. 1). 1. On the walking compensator an animal runs stable courses with a preferred direction relative to an air current (velocity =; 100 cm/s, Fig. 2B-D). A change in the air-current direction causes a corresponding adjustment of the mean walking direction (Fig. 3). Such course adjustment works best for changes in the air-current direction by an absolute value of 90° (Table 2). 2. Under closed-loop conditions the animal shows deviations of less than ± 45° around its preferred direction relative to the wind (Fig. 2B-D). The characteristic curve which describes the animal's angular velocity as a function of the animal's walking direction relative to the air-current stimulus is therefore revealed only in this angular range (Fig. 3, top). 3. Under open-loop conditions, however, complete characteristic curves can be obtained because the animal's walking reaction in response to any given angle of air-current stimulus is measurable on the paired tread wheel (Fig. 4). The characteristic curves are approximately sinusoidal functions. They can either show a shift parallel to the ordinale by a superimposed direction-independent constant angular velocity alone or, at the same time, they can independently exhibit an angular shift along the abscissa (Fig. 5). 4. The walking tracks straighten with increasing air-current velocity (Fig. 6A, insets), i.e. the animal more rapidly compensates deviations from a preferred course. This corresponds to higher amplitudes of the characterisic curve and steeper slopes at the negative zero-crossing point under open- as well as under closed-loop conditions (Fig. 6). 5. Walking in an air-current field can be explained by a model of the course control system using a feedback loop (Fig. 7). This model operates according to a sinusoidal characteristic function on which is superimposed a Gaussian white noise process of angular velocity which is independent of walking direction. The model produces realistic walking tracks in an air-current field (Fig. 8).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00194896
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  • 6
    Electronic Resource
    Electronic Resource
    Aerodynamic and mechanical properties of the antennae as air-current sense organs inLocusta migratoria (1987)
    Springer
    Journal of comparative physiology 161 (1987), S. 671-680 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The antennae of locusts,Locusta migratoria, act as vibration-sensitive air-current sense organs, by measuring deflections of the flagellum with the mechanoreceptors of the pedicellus. We analyzed the mechanical properties of the flagellum and its dynamic characteristics which are both a prerequisite for the evaluation of the adequate stimulus for the pedicellar mechanoreceptors and their possible role in flight control. 1. The locust antenna has a resonant frequency between 70–132 Hz when the flagellum is vibrated by head movements (Figs. 2, 3). Vibrations of 20 Hz (wing-beat frequency) cause only small amplitude deflections. A superimposed steady air stream has little effect on flagellar vibrations whereas a reduction of the antennal angle (γ) corresponding to the locust's antennal-positioning reaction during flight causes a reduction of the vibration amplitude (Fig. 4). 2. Kármán vortices behind the flagellum have frequencies in the range 1.5–6 kHz and are not sufficient to cause flagellar vibrations. 3. Flagellar vibrations are also produced by turbulent air streams (Figs. 1, 5, 8). In flying locusts the beating wings generate velocity modulations of the oncoming air stream with an amplitude (peak-to-peak) of 0.1–0.3 m/s in the region of the antennae (Fig. 6). Such modulations cause flagellar vibrations with amplitudes (aboutβ=0.03°, Fig. 7) which are known to be above threshold for the pedicellar sensilla campaniformia. The sensitivity of the flagellum for air current modulations at wing-beat frequency corresponds to a frequency response curve which exhibits amplitudes at 20 Hz to be nearly as large as at the resonant frequency of 125–180 Hz (Fig. 9a). The deviation of the flagellum shows a phase lag relative to the air particle velocity which is small near 20 Hz and reaches −90° at resonance (Fig. 9b). 4. Free flagellar vibrations are aperiodically damped (Fig. 10b), or 2–3 oscillations are superimposed on the aperiodic decay (Fig. 10a).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00605008
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  • 7
    Electronic Resource
    Electronic Resource
    Activity of Command Fibres in Free-Ranging Crayfish, Orconectes limosus Raf. (1997)
    Springer
    Naturwissenschaften 84 (1997), S. 408-410 
    Details
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001140050419
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  • 8
    Electronic Resource
    Electronic Resource
    Das Nervensystem des Flußkrebsmagens (1997)
    Weinheim : Wiley-Blackwell
    Biologie in unserer Zeit 27 (1997), S. 56-64 
    Details
    ISSN: 0045-205X
    Keywords: Life and Medical Sciences
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Seit jeher hat den Menschen die Frage fasziniert, wie Lebewesen ihre Umwelt wahrnehmen und wodurch ein bestimmtes Verhalten verursacht wird. Heute weiß man, daß die Informationsverarbeitung im Zentralnervensystem die Grundlage des Verhaltens ist. Von besonderer Bedeutung ist dabei die Verschaltung einzelner Nervenzellen in neuronalen Netzwerken, da sie den koordinierten Ablauf einer Bewegung gewährleisten.Diese Netzwerke interessieren zunehmend die öffentlichkeit, seit interdisziplinäre Forschergruppen aus den Bereichen Medizin, Biologie, Informatik und Ingenieurwissenschaften versuchen, die Funktionsprinzipien biologischer Netzwerke nachzuahmen. Mit Hilfe lernfähiger, sich selbst vernetzender Schaltungen sollen technische neuronale Netze zukünftig in der Lage sein, die Auswertung von Satellitenoder Personenbildern zu übernehmen Außerdem besteht die Hoffnung, bessere neuronale Prothesen zu entwickeln, die Patienten die Fähigkeit zum Hören, Sehen oder Laufen Zurückgeben Können.Komplizierten Bewegungsmustern, wie Laufen, Schwimmen, Sprechen und Schreiben, liegen durch die Evolution angepaßte neuronale Aktivitätsmuster zugrunde. Diese Erregungsmuster werden von miteinander vernetzten Nervenzellen im Zentralnervensystem generiert und kontrolliert. Die Untersuchung von einigen Modellsystemen in der Neurobiologie hat gezeigt, daß biologische Netzwerke auf gemeinsamen Bausteinen oder Funktionsprinzipien basieren.Ein hervorragendes Modellsystem zur Untersuchung dieser universellen Bausteine ist das stomatogastrische Nervensystem der Krebse [1] (griech. stoma - Mund, gastër - Magen). Dieses System wurde von einer Reihe internationaler Forschergruppen ausgewählt, da es nicht nur im Tier (Abbildung 1), sondern auch außerhalb des Tieres die neuronale Aktivität für vier verschiedene, rhythmische Bewegungen erzeugen kann.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/biuz.960270118
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  • 9
    Electronic Resource
    Electronic Resource
    Das Experiment: Neurophysiologische Versuche am intakten Regenwurm. Tierschutz durch Alternativen (1990)
    Weinheim : Wiley-Blackwell
    Biologie in unserer Zeit 20 (1990), S. 308-313 
    Details
    ISSN: 0045-205X
    Keywords: Life and Medical Sciences
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Der zuckende Froschschenkel gilt als das klassische Präparat zur Erforschung von Nervenfunktion und Muskelkontraktion. Am Froschbein mit seinem Ischiasnerven konnte Galvani um 1790 zeigen, daß es elektrische Vorgänge sind, die bei der Funktion von Nerven und Muskeln eine Rolle spielen. Sein Zeitgenosse und Kollege Volta benutzte ein solches Präparat als damals empfindlichstes „Meßinstrument“ fur schwache Ströme und schuf damit die Grundlagen zur Elektrizitätslehre. Diese historische Bedeutung ist ein Grund dafür, daß auch heute noch viele Biologie- und Medizinstudentinnen derartige Froschpräparate anfertigen müssen, um die Grundlagen der Funktionsweise von Nerven und Muskeln zu erlernen.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/biuz.19900200617
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