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In this study, technetium-99 ((99)Tc)-hexamethylpropyleneamine-oxine single-photon emission computed tomography (SPECT) was performed on 13 children with classic lissencephaly (nine with epileptic seizures, four without seizures). Focal or multifocal hypoperfusions were observed in 12 patients. The hypoperfused areas observed on SPECT scanning did not correlate with the localization of agyric-pachygyric regions in all patients. The distribution of perfusion abnormalities by SPECT and the localization of agyria-pachygyria as detected by magnetic resonance imaging did not correlate strongly. All nine patients with seizures and three of the four patients without seizures had focal or multifocal cerebral blood flow abnormalities on the SPECT scans. The presence of brain perfusion abnormalities detected by SPECT and the occurrence of epileptic seizures did not have a significant relationship. These results suggest that the role of SPECT studies in classic lissencephaly is not clearly defined. More sophisticated methods are needed to clarify the correlation between structural and functional abnormalities of patients diagnosed with lissencephaly.

In this paper, the longitudinal vibrations of a follower which is the linear active component of a cam mechanism is studied as if it has a constant cross section. The basic Bernoulli method is applied to solve the partial differential equation which is supplied by taking the viscous damping factor into consideration and by adding a new term. For the first time, in addition to the viscous damping, in this investigation, the internal damping term has been imposed to the motion of the follower. The resultant integration constants are determined by using the boundary conditions, and the eigen frequencies are calculated. As a result, two different families of eigen frequencies are remained. The results are formed as computer graphics to be easily understandable.

Zusammenfassung In der vorliegenden Arbeit werden die Biegeschwingungen der Antriebswelle des Kurvengetriebes mit Stoβel untersucht. In dem betrachteten Modell werden Torsionsdeformationen vernachlassigt. Die Bewegungsdifferentialgleichung wird in allgemeiner Form hergeleitet, vereinfacht und gelost. Die gefundenen Resultate werden bildich dargestellt und diskutiert.

This study deals with the torsional vibrations on the camshafts in force closed cam mechanisms. On the cam mechanisms with reciprocating followers, the variable torque which is produced by force exerted to the cam from the follower, will create torsional vibrations on the camshaft. A dynamic model of the camshaft was established and some nondimensional parameters which can be used to characterize dynamic behaviour of a camshaft were obtained. Torsional vibrations of camshafts are parametric and self-induced vibrations. The governing nonlinear differential equations were solved numerically. Vibrations of camshafts with a flat-faced follower differ from ones with a roller follower because of the friction between cam and follower. Vibrations on the camshaft affect the follower motion and contact force.