Packing of elastic wires in spherical cavities.

We investigate the morphologies and maximum packing density of thin wires packed into spherical cavities. Using simulations and experiments, we find that ordered as well as disordered structures emerge, depending on the amount of internal torsion. We find that the highest packing densities are achieved in low torsion packings for large systems, but in high torsion packings for small systems. An analysis of both situations is given in terms of energetics and comparison is made to analytical models of DNA packing in viral capsids.

Biophysical parameters modification could overcome essential hearing gaps.

A majority of hearing defects are due to malfunction of the outer hair cells (OHCs), those cells within the mammalian hearing sensor (the cochlea) that provide an active amplification of the incoming signal. Malformation of the hearing sensor, ototoxic drugs, acoustical trauma, infections, or the effect of aging affect often a whole frequency interval, which leads to a substantial loss of speech intelligibility. Using an energy-based biophysical model of the passive cochlea, we obtain an explicit description of the dependence of the tonotopic map on the biophysical parameters of the cochlea. Our findings indicate the possibility that by suitable local modifications of the biophysical parameters by microsurgery, even very salient gaps of the tonotopic map could be bridged.

Tarsal tunnel syndrome: clinical and pathological results.

The tarsal tunnel syndrome is a complex entity. The condition results from a compression of the posterior tibial nerve, either at its terminal or collateral branches, at the tibio-astragalo-calcaneal canal of Richet. A retrospective study of 27 consecutive cases, treated by epi- or perineural neurolysis, illustrates the variability of the clinical picture but fails to confirm the complete and immediate success of the intervention, as reported by the majority of authors. However, the long-term follow-up shows a significant improvement in the terminal latencies of the posterior tibial nerve at 2 years post-surgery. A pathological study of 20 cadaveric feet discloses microscopic anomalies in 22 of the 120 nerve biopsy specimens.

Morphological phases of crumpled wire.

We find that in two dimensions wires can crumple into different morphologies and present the associated morphological phase diagram. Our results are based on experiments with different metallic wires and confirmed by numerical simulations using a discrete element model. We show that during crumpling, the number of loops increases according to a power law with different exponents in each morphology. Furthermore, we observe a power law divergence of the structure's bulk stiffness similar to what is observed in forced crumpling of membranes.

Natural computation measured as a reduction of complexity.

We argue that the deeper nature of computation is to reduce the statistical obstruction against prediction. From this, we derive an explicit measure of computation for general, artificial as well as natural, systems (electronic circuits, neurons, mechanical devices, etc.). The applicability and usefulness of this concept is demonstrated using well-studied families of dynamical systems, as well as experimental time series from cortical neurons.

Lisfranc's fracture-dislocations: etiology, radiology, and results of treatment. A review of 20 cases.

Tarsometatarsal fracture-dislocation is an uncommon but severe lesion. Since this diagnosis is over-looked in about 20% of cases, accurate radiographic examination is imperative. In the presence of suggestive clinical signs and negative standard roentgenograms, stress-films in eversion-pronation and inversion-supination are obtained under general anaesthesia. A review of 20 cases shows that plaster cast immobilization without reduction is unsatisfactory, often resulting in Südeck's atrophy and subsequent painful degenerative arthritis. Secondary fusion may be necessary to relieve symptoms. The treatment of choice is anatomic reduction and transfixation with Kirschner wires. The major complication is arterial damage with necrosis of the forefoot. Amputation may be necessary.

Posterior subtalar joint arthrography. A useful tool in the diagnosis of hindfoot disorders.

Obscure hindfoot disorders are often classified under the heading of sinus tarsi syndrome (STS). The diagnosis of STS is based upon subjective symptoms: tenderness over the lateral aperture of the sinus tarsi and hindfoot instability. Arthrography of the posterior subtalar joint is an objective parameter, identifying peri- or intraarticular pathology as the cause of symptoms. In 27 patients with STS, the pathologic arthrographic findings include less-marked microrecesses in the sinus tarsi region, ganglions at the anterior aspect of the subtalar joint, retraction of the joint recesses, a smooth and rounded appearance of the capsule, and a frozen subtalar joint. Through analysis of these films, the appropriate therapeutic approach can be outlined; infiltrations into the sinus tarsi itself, intraarticular corticosteroid injections, or subtalar arthrodesis for resistant cases are the procedures of choice. In the authors' experience, surgical curettage of the sinus tarsi has no place in the treatment of STS.