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Biomedical subjects

W Lenne

Publications and source records attributed to W Lenne.

6 recordsLinked to original sources
PubMed1987

Generalization of the Tscherning theory: optimization of aspheric ophthalmic lenses.

The perfect single vision ophthalmic lens should be free from oblique astigmatism, mean oblique error, distortion and chromatism. At the same time, it should be aesthetic and comfortable. By means of third-order theory, we show that T scherning ellipses can be considered to correspond merely to the particular case in which the lens surface is spherical in the three-dimensional space defined by the conic constant epsilon, the power of the first surface D1, and the back vertex power D. Consideration is given to the best way of building a merit function for final optimization with a classical ray tracing optimization program on a computer.

Color Perception↗
PubMed1975

[Interpretation of the limits of survival during circulatory support in the dog].

A total cardiac supplementation through a simple by-pass of the left ventricle was performed on hearts in ventricular fibrillation on 51 dogs not treated with heparin. The right-sided circulation was passive to avoid introducing added disturbing parameters. A bi-valved supple prosthesis was set in motion by a pneumatic pump regulated on the left atrial pressure and the arterial tree proper rate. The 44 cases which survived from 7 to 27 hours were limited by a slow and regular lowering of the blood pressure without notable decrease of the output. This lowered pressure was due to the action of the atrial and pulmonary mechanical receptors responding to a left atrial hypertension, secondary to a mild leak of the inflow valve. The mild haemolysis and the total absence of thrombosis should be related with the rate-regulation of the pump on the arterial tree rate, thus providing a maximal yield.

Animals↗