The classification of lattice equations that are integrable in the sense of higher-dimensional consistency is extended by allowing directed edges. We find two cases that are not transformable via the 'admissible transformations' to the lattice equations in the existing classification.
By imposing special compatible similarity constraints on a class of integrable partial q-difference equations of KdV-type we derive a hierarchy of second-degree ordinary q-difference equations. The lowest (non-trivial) member of this hierarchy is a second-order second-degree equation which can be considered as an analogue of equations in the class studied… (More)
The study describes 51 patients, aged 10 to 57 years, who underwent spinal surgery (47) or interventional angiography (4). Multi-channel somatosensory evoked potential (SEP) monitoring was used to measure the functional integrity of the spinal cord. Alternating unilateral tibial SEPs permitted the detection of lateralised and milder abnormality. A… (More)