Structure refinement from precession electron diffraction data.

Electron diffraction is a unique tool for analysing the crystal structures of very small crystals. In particular, precession electron diffraction has been shown to be a useful method for ab initio structure solution. In this work it is demonstrated that precession electron diffraction data can also be successfully used for structure refinement, if the dynamical theory of diffraction is used for the calculation of diffracted intensities.

[Posttraumatic infarction with a surgically treated floating thrombus of the left ventricle. Apropos of a case].

Forty-two days after severe thoracic trauma which had led to thrombosis of the left renal artery and to nephrectomy, a 22 year old patient developed anterior wall infarction. Echocardiography and coronary and left ventricular angiography showed distal occlusion of the left anterior descending artery and the presence of a large, mobile thrombus at the left ventricular apex. The thrombus was removed surgically without any complications but a small thrombus adherent to the ventricular scar was observed postoperatively.

[Echography in pneumopericardium. Value of the subxiphoid approach].

Para-sternal echocardiography proved impossible in a case of a large pneumopericardium caused by an oesophageo-pericardial fistula. However, M mode and sector scanning showed separation of the pericardium, giving non-homogeneous echoes, and shaded echographic areas caused by the interference of air which masked all recognisable structures. This occurred in time with systole, a sign which we associate with the pneumopericardium itself.