Biomedical subjects
Matthias Winter
Publications and source records attributed to Matthias Winter.
Stability analysis of Turing patterns generated by the Schnakenberg model.
We consider the following Schnakenberg model on the interval (-1,1): [formula see text] where D1 > 0, D2 > 0, B > 0. We rigorously show that the stability of symmetric N-peaked steady-states can be reduced to computing two matrices in terms of the diffusion coefficients D1, D2 and the number N of peaks. These matrices and their spectra are calculated explicitly and sharp conditions for linear stability are derived. The results are verified by some numerical simulations.
The intermetatarsal articular facet of the first metatarsal bone in humans: a derived trait unique within primates.
The occurrence and morphology of an intermetatarsal facet of the first metatarsal bone have been investigated in a series of 306 nonhuman primates representative of 40 genera, and in a series of 412 human metatarsal bones (dried bones) (215 left, 197 right). In nonhuman primates, no case of intermetatarsal facet was observed in the 306 first metatarsal bones studied. In humans, a well-defined intermetatarsal facet was observed in 127 out of the 412 bones (30.8%); no significant difference was observed between the left and right sides. The shape of the facet was elliptical, more or less elongated; it had a mean major axis (height) of 10.7 mm, and a mean minor axis (width) of 6.1 mm (extremes: 5 x 3 mm and 17 x 10 mm). The facet was located in the dorsal third of the lateral side of the first metatarsal in 103 out of 127 cases (81.1%), and in the middle third in 24 out of 127 cases (18.9%); it was never observed in the plantar third. The intermetatarsal facet was in connection with the proximal articular facet for the medial cuneiform in 68 out of 127 cases (53.5%), and it was separated from the proximal facet by a small nonarticular area or groove in 59 out of 127 cases (46.5%). The present observations suggest that the human first intermetatarsal facet is a derived trait unique within primates (autapomorphy) which is present in approximately one third of individuals. The appearance of this new articular facet in human evolution seems clearly related to the morphological modifications of the foot due to the acquisition of bipedalism, and more particularly to the loss of abductability of the hallux and its permanent adduction.
[Hemiatrophia faciei progressiva and tonic pupil].
BACKGROUND: A variety of infectious and autoimmune diseases are described in association with pupillotonia. To our knowledge there is only one report on pupillotonia associated with hemiatrophia faciei. We describe another patient with this rare association. The aim is to investigate possible associations between both diseases. PATIENT: A twenty five-year-old male patient with hemiatrophia faciei, epilepsy and pupillotonia of the right eye since his twelfth birthday was presented for the first time at the age of fourteen at our institution. The patient underwent a complete neurological and paediatric as well as otolaryngological investigation; there was also an investigation by the internist. The patient also underwent a complete serological investigation for infectious and autoimmune disorders as well as an investigation of the local and systemic vascular reactivity by the "Ocular cold pressor test". The follow-up time is 11 years. RESULTS: The clinical picture of our patient was an association of hemiatrophia faciei, epilepsy and pupillotonia. There was no evidence of a local hyperactivity of the sympathetic nervous system. The serological investigation showed an elevated value of antinuclear antibodies. CONCLUSIONS: We assume that in our case the pupillotonia as well as the hemiatrophia faciei and the epilepsy is caused by a common autoimmune factor. All other aetiologies for these three diseases were excluded. Furthermore, the occurrence of pupillotonia, hemiatrophia faciei and epilepsy was simultaneous.