4,216 research outputs found
Species-Specific Flight Styles of Flies are Reflected in the Response Dynamics of a Homolog Motion-Sensitive Neuron
Full text linkGeurten BRH, Kern R, Egelhaaf M. Species-Specific Flight Styles of Flies are Reflected in the Response Dynamics of a Homolog Motion-Sensitive Neuron. Frontiers in Integrative Neuroscience. 2012;6:11.Hoverflies and blowflies have distinctly different flight styles. Yet, both species have been shown to structure their flight behavior in a way that facilitates extraction of 3D information from the image flow on the retina (optic flow). Neuronal candidates to analyze the optic flow are the tangential cells in the third optical ganglion – the lobula complex. These neurons are directionally selective and integrate the optic flow over large parts of the visual field. Homolog tangential cells in hoverflies and blowflies have a similar morphology. Because blowflies and hoverflies have similar neuronal layout but distinctly different flight behaviors, they are an ideal substrate to pinpoint potential neuronal adaptations to the different flight styles. In this article we describe the relationship between locomotion behavior and motion vision on three different levels: (1) We compare the different flight styles based on the categorization of flight behavior into prototypical movements. (2) We measure the species-specific dynamics of the optic flow under naturalistic flight conditions. We found the translational optic flow of both species to be very different. (3) We describe possible adaptations of a homolog motion-sensitive neuron. We stimulate this cell in blowflies (Calliphora) and hoverflies (Eristalis) with naturalistic optic flow generated by both species during free flight. The characterized hoverfly tangential cell responds faster to transient changes in the optic flow than its blowfly homolog. It is discussed whether and how the different dynamical response properties aid optic flow analysis
Optomotor course control in flies with largely asymmetric visual input
Full text linkKern R, Egelhaaf M. Optomotor course control in flies with largely asymmetric visual input. Journal of Comparative Physiology A. 2000;186(1):45-55
Wilm Pelters : Lessings Standort. Sinndeutung der Geschichte als Kern seines Denkens, 1972
No full textKrebs Roland. Wilm Pelters : Lessings Standort. Sinndeutung der Geschichte als Kern seines Denkens, 1972. In: Dix-huitième Siècle, n°7, 1975. p. 405
A remotely controlled lightweight MRI compatible ultrasonic actuator for micrometer positioning of electrodes during neuroethological primate research.
No full textInterview with Roland Abraham
No full textInterview with Roland Abraham, who is a former director of the Minnesota Extension Service. He is the author of Helping People Help Themselves: Agricultural Extension in Minnesota, 1879 to 1979. Abraham talks about how he got to the university and about the Minnesota Extension Service.Abraham, Roland H.; Pflaum, Ann M.. (1999). Interview with Roland Abraham. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/47871
Chasing Behavior and Optomotor Following in Free-Flying Male Blowflies: Flight Performance and Interactions of the Underlying Control Systems
Full text linkTrischler C, Kern R, Egelhaaf M. Chasing Behavior and Optomotor Following in Free-Flying Male Blowflies: Flight Performance and Interactions of the Underlying Control Systems. Frontiers in Behavioral Neuroscience. 2010;4:1-13
The death of William Golding: authorship and creativity in darkness visible and the paper men
Full text linkIn the seventies and eighties William Golding was deeply responsive to the critical, anti-authorial ethos that followed the publication of Roland Barthes's "La mort de I'auteur" (1968). In Darkness Visible (1979) and The Paper Men (1984) he investigates means by which to reaffirm authorial presence. Working through paradox, he performs the authorial death in these novels, and establishes language’s inadequacy as a means of conveying absolute meaning, authorial "vision," truth or revelation. Having done so he nonetheless gestures towards the divine, towards the possibility of a vatic communication. In this manner the novels work upon principles of contradiction and collapse. What remains is a discourse of hope, promise, desire, without means of substantiating such optimism. Thus Golding might be said to have practiced a form of negative theology, and to have anticipated in this respect some recent trends in literary theory
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
On the remote sensing of oceanic and atmospheric convection in the Greenland Sea by synthetic aperture radar
No full textIn this paper we discuss characteristic properties of radar signatures of oceanic and atmospheric convection features in the Greenland Sea. If the water surface is clean (no surface films or ice coverage), oceanic and atmospheric features can become visible in radar images via a modulation of the surface roughness, and their radar signatures can be very similar. For an unambiguous interpretation and for the retrieval of quantitative information on current and wind variations from radar imagery with such signatures, theoretical models of current and wind phenomena and their radar imaging mechanisms must be utilized. We demonstrate this approach with the analysis of some synthetic aperture radar (SAR) images acquired by the satellites ERS-2 and RADARSAT-1. In once case, an ERS-2 SAR image an a RADARSAT-1 ScanSAR image exhibit pronounced cell-like signatures with length scales on the order of 10-20 km and modulation depths of about 5-6 dB and 9-10 dB, respectively. Simulations with a numerical SAR imagaing model and various input current and wind fields reveal that the signatures in both images can be expained consistently by wind variations on the order of±2.5 ms, but not by surface current variations on realistic orders of magnitude. Accordingly, the observed features must be atmospheric convection cells. This is confirmed by visible typical cloud patterns in a NOAA AVHRR image of the test scenario. In another case, the presence of an oceanic convective chimney is obvious from in situ data, but no signatures of it are visible in an ERS-2 SAR image. We show by numerical simulations with an oceanic convection model and our SAR imaging model that this is consistent with theoretical predictions, since the current gradients associated with the observed chimney are not sufficiently strong to give rise to significant signatures in an ERS-2 SAR image under the given conditions. Further model results indicate that it should be generally difficult to observe oceanic convection features in the Greenland Sea with ERS-2 or RADARSAT-1 SAR, since their signatures resulting from pure wave-current interaction will be too weak to become visible in the noisy SAR images in most cases. This situation will improve with the availability of future high-resolution SARs such as RADARSAT-2 SAR in fine resolution mode (2004) and TerraSAR-X (2005) which will offer significantly reduced speckle noise fluctuations at comparable spatial resolutions and thus a much better visibility of small image variations on spatial scales on the order of a few hundred meters
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