Two scaling domains in multiple cracking phenomena

The fragmentation of two-phase composite systems such as coatings on substrates and fibers in matrices under uniaxial tension shows two regimes: the evolution of the mean fragment length with applied strain displays different power laws for small and for large strains. From theoretical arguments, we find that in both cases the scaling exponent depends on the shape parameter of the strength distribution. The exponent for large applied strains depends also, as we show, on the way (linear or nonlinear) in which the stress transfer between the two constituents takes place. We present experimental data on the sequential cracking of SiOx coatings on thermoplastic substrates that indeed show the two regimes; the detailed analysis of the data supports our theory.

[Osteoblastomas of the coccyx. Apropos of a case. Review of the literature]. / Les ostéoblastomes du coccyx. A propos d'une observation. Revue de la littérature.

A 24-year-old man presented with a painful and invalidating coccyx. Exploration revealed a bony lesion involving parts of 2nd and all of the 3rd coccygeal vertebrae. The pathology examination of the surgical specimen revealed the diagnosis of benign osteoblastoma of the coccyx. This exceptional localization required complete surgical resection going into healthy tissues to allow a full histological study and to ensure the absence of relapse. Post-operative follow-up was uneventful and the functional result was excellent.

[Traumatic lesions of the supra-hepaticocaval veins or lessons from failure. Apropos of 5 cases]. / Les lésions traumatiques des veines sus hépatico-caves ou les leçons de l'échec. A propos de 5 observations.

Strategic therapeutic principles in 5 cases of injury to supra-hepaticocaval veins were based on vascular exclusion of liver prior to any approach to the lesion. An approach to the intrapericardial inferior vena cava by sternotomy is proposed together with the use of an endocaval shunt introduced through the atrium.

Traumatic rupture of the thoracoabdominal aorta.

We report a case of traumatic rupture of the thoracoabdominal aorta that was successfully repaired 3 days following the accident. Associated lesions included rupture of the left renal and celiac arteries. This rare lesion should be suspected in the victims of violent hyperextension of the body with or without a fracture of the dorsolumbar spine. Aortography is diagnostic. Whenever possible preoperative angiographic visualisation of the spinal cord arterial supply should be performed.

[A comparative mechanical study of types of external fixator (author's transl)]. / Etude mécanique comparative de fixateurs externes. Le modèle du Service de Santé des Armées.

The authors have designed and original type of external fixator which can be used in the forces in case of armed conflict. Study has been directed towards a simple, strong and inexpensive apparatus which can be applied in emergency circumstances. Secondarily it can be replaced by another apparatus to allow compression, distraction or better reduction of a fracture without removal of the pins. The fixator should be applied as close as possible to bone and there should be three pins in each fragment, one close to the fracture, one distant and one intermediate. The best methods for the insertion of the pins have been tested.