We analyze the full set of constraints on gluino-and photino-mediated SUSY contributions to FCNC and CP violating phenomena. We use the mass insertion method, hence providing a model-independent parameterization which can be readily applied in testing extensions of the MSSM. In addition to clarifying controversial points in the literature, we provide a more exhaustive analysis of the CP constraints, in particular concerning ε ′ /ε. As physically meaningful applications of our analysis, we study the implications in SUSY-GUT's and effective supergravities with flavour non-universality. This allows us to detail the domain of applicability and the correct procedure of implementation of the FC mass insertion approach.

The lobula giant motion detector (LGMD) in the locust visual system is a wide-field, motion-sensitive neuron that responds vigorously to objects approaching the animal on a collision course. We investigated the computation performed by LGMD when it responds to approaching objects by recording the activity of its postsynaptic target, the descending contralateral motion detector (DCMD). In each animal, peak DCMD activity occurred a fixed delay ␦ (15 Յ ␦ Յ 35 msec) after the approaching object had reached a specific angular threshold thres on the retina (15°Յ thres Յ 40°). thres was independent of the size or velocity of the approaching object. This angular threshold computation was quite accurate: the error of LGMD and DCMD in estimating thres (3.1-11.9°) corresponds to the angular separation between two and six ommatidia at each edge of the expanding object on the locust retina. It was also resistant to large amplitude changes in background luminosity, contrast, and body temperature. Using several experimentally derived assumptions, the firing rate of LGMD and DCMD could be shown to depend on the product (t Ϫ ␦) ⅐ e Ϫ␣(tϪ␦) , where (t) is the angular size subtended by the object during approach, (t) is the angular edge velocity of the object and the constant, and ␣ is related to the angular threshold size [␣ ϭ 1/tan( thres /2)]. Because LGMD appears to receive distinct input projections, respectively motion-and size-sensitive, this result suggests that a multiplication operation is implemented by LGMD. Thus, LGMD might be an ideal model to investigate the biophysical implementation of a multiplication operation by single neurons.

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Sensitivity of excitatory LGMD input to the speed of object motion. Figure S1 below illustrates an experiment that demonstrates the sensitivity of local excitatory input to theLGMD to the speed of object motion. In these experiments, a small black disk (see Krapp and Hengstenberg, Vis. Res., 1997, 37:225-234 for details) was moved at various speeds