When multiple sclerosis (MS) presents late in life (after the age of 50), it frequently gives diagnostic difficulty. In a large MS clinic population (N = 838), 9.4% of the patients had late onset of MS. Slow deterioration of motor function characterized the initial symptoms and subsequent course of this group of older patients. Progression of disability was more rapid than in younger patients. Evoked response studies and CSF electrophoresis were of high diagnostic yield in the older patient group. Reasons for the differing clinical features in the late-onset patients are discussed. We suggest that the age-of-onset criterion for MS be raised to 60 in adequately investigated cases.

No abstract

This paper is concerned with the use of spectral analysis to analyze data generated by computer simulation experiments with models of economic systems. An example model serves to illustrate two different applications of spectral analysis. First, spectral analysis is used to construct confidence bands and to test hypotheses for the purpose of comparing the results of the use of two or more alternative economic policies. Second, spectral analysis is employed as a technique for validating an econometric model.

The purpose of this study is to examine quantitatively the branching characteristics of the coronary arteries. Branching angles and vessel diameters were measured in a total of 175 arterial bifurcations in the coronary beds of rats, and the results are compared with those of 350 bifurcations in other parts of the cardiovascular system of the same species. Significant differences are found in the values of branch diameters and branching angles, both being found generally lower in the coronary bed than in other parts of the system. On statistical grounds these differences are found to have very high significance levels, with P values less than 0.02 in the case of branching angles and much less than 0.001 in the case of branch diameters. On physiological grounds, the differences are such as to place the coronary arteries further away from the "theoretical optimum" than are vessels in other parts of the cardiovascular system. The theoretical optimum represents branching angles and branch diameters which make arterial bifurcations more efficient physiologically.

No abstract