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The theory of the growth of the total first-order Raman stokes power with the corresponding depletion of the laser pump power in optical fibers is examined. Numerical solutions are given for circumstances where the losses at the pump and Stokes wavelengths are unequal. The nature of the power-coupling process and the depletion of the total power at all wavelengths can be described without a full analytical solution. The variation of the output power with respect to input power when the fiber length is a constant is also studied.

Granular cell myoblastoma is a relatively uncommon lesion of disputed histogenesis which is seen most frequently in the subcutaneous tissues and in the tongue (Strong, McDivitt and Brasfield, 1970). It rarely occurs in the bronchus; Weitzner and Oser in a search of the literature could only find 30 cases to which they added one of their own.Many authors have discussed the origin and nature of the lesion, some regarding it as nonneoplastic, either a degenerative reaction (Ewing, 1940; Willis, 1960) or a storage disorder (Azzopardi, 1956; Shear, 1960), but most regarding it as neoplastic. However, the latter disagree on the cellular origin of the neoplasm, the suggestions being neural (Ashburn and Rodger, 1952; Fisher and Wechsler, 1962), myogenic (Murphy, Dockerty and Broders, 1949), fibroblastic (Pearse, 1950) and mesenchymal (Toto and Restarski, 1967).Reviewing the available evidence and adding evidence of their own from electron microscopic studies, Garancis, Komorowski and Kuzma (1970) have favoured an origin from the Schwann cell and this remains the most popular hypothesis.In view of the rarity of the lesion in the bronchus we would like to discuss briefly the rather unusual bronchographic appearances.

In today’s competitive industrial environment, the quality of a product is no longer the major factor which influences purchase by a customer, it is simply a prerequisite for competing in the market. To compete and survive, the necessity is to provide the product at an affordable price, a target that can only be attained through actions such as improving the efficiency of manufacturing operations. In sheet metal industries, the cost of tooling contributes a considerable part to the overall manufacturing cost of a component. It is imperative to keep this cost down by ensuring the tool operates uninterrupted for long periods of time, achievable in one way by reducing the stress on the tool during punching by optimizing the clearance between the die and the punch. This paper deals with this problem using finite element techniques. Having created models of various punch configurations, one is able to analyze the effect of variations in tool geometry on punching force and tool deformation, a parameter highly relevant in assessing performance in terms of the accuracy of machined components. Computed results using FE models are compared against results obtained through experimentation. Due to the nature of the punching process being inherently noisy, consideration was given to noise levels, how they are affected by changes in tool geometry, and the subsequent effect on the workforce considering the fact that reducing stress on the operator could only improve quality and productivity. Finally, some suggestions are given as to how the efficiency of a punching tool and quality of the punched product can be improved.

The growth of the Raman Stokes spectrum in single-mode optical fibers is studied in circumstances where there is a significant variation of loss with wavelength. It is shown that the dependence of pump and total Stokes power with fiber length can be calculated from only two equations when an effective Stokes loss is used. The effective Stokes loss is calculated both analytically and numerically for a linear increase of loss with wavelength. Good agreement is found for the two methods of computation.

A notch in the inferior border of the left atrium has been observed in patients with a persistent left superior vena cava draining via the coronary sinus into the right atrium. It is suggested that the notch is due to the dilated coronary sinus.

Twenty-seven children who survived total correction of Fallot's tetralogy are reviewed and 14 with suspected complications were reinvestigated by cardiac catheterisation and contrast studies. There were three late deaths. Of the remaining 24, 16 are well and have no evidence of complications other than pulmonary incompetence. One child has moderate residual pulmonary stenosis; there has been some reopening of the ventricular septal defect in six, all with a residual right ventricular/pulmonary artery systolic gradient of between 20 and 53 mm Hg (one has since had further surgical repair). One child developed marked pulmonary incompetence.The plain X-ray and angiocardiographic appearances are described. Dilatation of the infundibulum of the right ventricle was an important feature. It varied from a slight convexity to aneurysm formation. It gave a reliable indication of persistently raised right ventricular pressure, indicating persistent outflow obstruction, reopening of the ventricular septal defect, or both. A rapid increase in size was followed by death in one, and by successful re-operation in another child.The appearance of the pulmonary valves on angiocardiography was unreliable in the diagnosis of persistent pulmonary stenosis following operation unless there was distinct doming of the valves. Recatheterisation is the only certain method of detecting significant residual stenosis.Distortion of the appearance of the left ventricular outflow tract in systole appeared to be without functional significance.