Social hymenopterans such as bees and ants are central-place foragers; they regularly depart from and return to fixed positions in their environment. In returning to the starting point of their foraging excursion or to any other point, they could resort to two fundamentally different ways of navigation by using either egocentric or geocentric systems of reference. In the first case, they would rely on information continuously collected en route (path integration, dead reckoning), i.e. integrate all angles steered and all distances covered into a mean home vector. In the second case, they are expected, at least by some authors, to use a map-based system of navigation, i.e. to obtain positional information by virtue of the spatial position they occupy within a larger environmental framework. In bees and ants, path integration employing a skylight compass is the predominant mechanism of navigation, but geocentred landmark-based information is used as well. This information is obtained while the animal is dead-reckoning and, hence, added to the vector course. For example, the image of the horizon skyline surrounding the nest entrance is retinotopically stored while the animal approaches the goal along its vector course. As shown in desert ants (genus Cataglyphis), there is neither interocular nor intraocular transfer of landmark information. Furthermore, this retinotopically fixed, and hence egocentred, neural snapshot is linked to an external (geocentred) system of reference. In this way, geocentred information might more and more complement and potentially even supersede the egocentred information provided by the path-integration system. In competition experiments, however, Cataglyphis never frees itself of its homeward-bound vector - its safety-line, so to speak - by which it is always linked to home. Vector information can also be transferred to a longer-lasting (higher-order) memory. There is no need to invoke the concept of the mental analogue of a topographic map - a metric map - assembled by the insect navigator. The flexible use of vectors, snapshots and landmark-based routes suffices to interpret the insect's behaviour. The cognitive-map approach in particular, and the representational paradigm in general, are discussed.
Resonant cavity enhanced HgCdTe structures have been grown by molecular beam epitaxy, and photoconductors have been modelled and fabricated based on these structures. Responsivity has been measured and shows a peak responsivity of 8 × 10 4 V/W for a 50 × 50 µm 2 photoconductor at a temperature of 200K. The measured responsivity shows good agreement with the modelled responsivity across the midwave infrared window (3-5 µm). The measured responsivity is limited by surface recombination, which limits the effective lifetime to ≈ 15ns. The optical cut-off of the detector varies with temperature as modelled. There is strong agreement between modelled peak responsivity and measured peak responsivity with varying temperature from 80-300K.
Die kriminMistischen Ergebnisse bei der Aufldgrung der polnischen Grenel an Volksdeutschen ]assen sieh dahin zusammenfassen, dab sic in ihrer sehon bisher vorliegenden Gesamtheit den unerschfitterlichen Beweis ffir die furchtbarsten Massenverbrechen der Kriminalgeschich~e der letzten Jahrhunderte erbracht haben. Es erscheint mir wichtig, diese Tatsache angesichts der Feindpropaganda zu Beginn meiner Darlegungen besonders hervorzuheben.Meine Ausfiihrungen hierzu kSnnen in dem gestellten Rahmen se]bstverstgnd]ich diese kriminMistischen Ergebnisse nicht erseh5pfend darstellen oder erSrtern. Dazu ist das Gesamtergebnis sachlicher Mordaufklgrungstgtigkeit zu umfangreich und vielgestaltig.Die kriminMistische Bearbei~ung der an Volksdeutschen veriibten Greueltaten nahm innerhMb der ungeheuren polizeilichen Gesamtaufgaben naturgem/~B eine ihrer Bedeutung entsprechende Sonderstellung 1 geferat~.
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