Net Present Value from Complex Cash Flow Streams by Simulation

In models previously developed for the purpose of obtaining net present value from a stream of discounted cash flow increments, it is difficult to introduce complex economic, market and behavioral considerations without rendering the problem intractable computationally. Monte Carlo simulation with a digital computer, particularly in a simulation language, offers an attractive and feasible solution to the flexibility problem. This article illustrates the use of simulation techniques to find the net present value of a proposed project, together with its statistical distribution, when three types of phenomena are incorporated in the model: (1) long-term exponential market growth, (2) “non-instantaneous” response by the firm to price/elasticity fluctuations, and (3) imposition of arbitrary, yet reasonable, constraints on product output.     

Dihydrofolate reductase and thymidylate synthetase activities in the liver of rabbit foetuses during the haemapoietic period

Dihydrofolate reductase activity did not change with variations of mitotic rate in foetal rabbit haemopoietic tissue, whereas the activity of thymidylate synthetase declined with decrease in cell divisions. Both the activities were normal in the brachydactylia strain, in which a failure in folate metabolism was previously assumed.     

Comparison of mortality of patients with heart attacks admitted to a coronary care unit and an ordinary medical ward

During a 32-month period 2047 patients suspected of having heart attacks were admitted to hospital and were followed up prospectively. Out of 1480 eventually found to have definite or probable myocardial infarction, 483 had initially been admitted to an ordinary medical ward because of the shortage of coronary care unit (CCU) beds. More patients aged over 65 had been admitted to a ward than to a CCU, and more patients aged 65 or less had been admitted initially to a CCU. Within each age group, however, patients admitted initially to a CCU were clinically similar to those admitted initially to a ward. There was a higher proportion of successful resuscitations among patients admitted to a CCU, but there was no significant difference in mortality in either age group between patients admitted to a CCU and a ward.     

Fiberoptic transillumination: a new tool for the pediatric surgeon

Transillumination (TI) is a safe and reliable technique for evaluating masses or the presence of free air in the thorax or abdomen. TI can also be of help in the accurate placement of catheters or needles in the chest, abdomen, bladder, or vessels. Its use in several hundred cases has been documented by this report.     

Release of renal prostaglandins during endotoxin-induced hypotension

The appearance of prostaglandins in dog's blood during endotoxin-induced hypotension was studied by use of the dialysis modification of the blood bathed organ technique. An increase in prostaglandins, mainly E2 and F2alpha was found in renal venous blood, whereas no such increase was seen in blood from the abdominal aorta, the inferior vena cava or the femoral vein. Three possible trigger mechanisms for this increase i.e. hypotension, reduced flow and reflexogenic sympathetic stimulation, have been investigated. It is suggested that, in addition to these three factors, circulating hormones such as noradrenaline, angiotensin or bradykinin, play a role in this release mechanism. Administration of indomethacin produced a restoration of the systemic blood pressure to its pre-endotoxin value; concomitantly a disappearance of the prostaglandins from the circulation was observed. It is concluded that prostaglandins contribute to the hypotension induced by endotoxin. Whether they are beneficial or detrimental remains to be resolved.