SUMMAEY The theoretical basis of the log likelihood ratio test (the G‐test) is described, and instructions and tables are given for its use as a test of heterogeneity in contingency tables. There is a marked saving in computation time over the customary Karl Pearson test. It is a pleasure to thank Miss Mary Wheeler and Miss Madge Wight for the major part of the computations.
A provisional yardstick of human calorie requirements has been provided by a report from the Nutrition Division of the Food and Agricultural Organization (F.A.O.) of the United Nations (1950). In a world beset with food shortages and an increasing population this is of great practical importance.The report draws attention to several gaps in fundamental physiological knowledge. Thus the variation in the Basal Metabolic Rates (B.M.R.), the foundation upon which standards for human energy requirements have been built, is not well-defined in different population groups. Recently Quenouille, Boyne, Fisher & Leitch (1951) have made a new assessment of normal B.M.R. standards in relation to sex, stature, age, climate and race. Robertson & Reid (1952) have made measurements of the B.M.R.'S of a large series of the British people. These authors have discussed body size, age, sex and race in relation to B.M.R.'S. We now have a good body of data on this subject, but there is little or no data of the effect of these factors on the metabolism during muscular activities. If metabolic variations of the same order occurred during exercise, they would profoundly affect the food requirements of a population.In the present investigation we have studied the energy expenditure of fifty persons of varying size and age, male and female, European and Asiatic, during the carrying out of two different standard muscular activities. The first one was a stepping test in which there was measurable external work performed in raising the body weight and the second was walking, an ordinary everyday activity. In these two activities the movements involved are those to which the subjects are of necessity accustomed in every-day life, and so should be little affected by training or practice.A statistical analysis of our data shows that energy expenditure during stepping or walking can be very closely predicted from a knowledge of body weight, and that no significant increase in precision is gained by also taking PH. CXXI. 15
IT is an old observation that when fumaric acid, maleic acid or malic acid is heated in the presence of ammonia in a sealed tube to 2000 a conversion to aspartic acid occurs. There has been no evidence, however, that such a conversion can take place under biological conditions. Experiments which will be described in this paper show that l-aspartic acid is formed in a solution containing sodium fumarate, ammonium chloride and resting bacteria, no amino-acid being synthesised in the absence of the bacteria. The yield of l-aspartic acid, obtained under certain conditions, has been as high as 60 % of the fumaric acid taken. A small amount of aspartic acid is synthesised from malic acid but none, under our experimental conditions, from maleic acid. The results of experiments on oxidations, etc., in the animal body make it highly probable that the production of a-hydroxy-acids from a-amino-acids takes place via the a-ketonic acids. It will be shown in this paper, however, that aspartic acid in presence of resting bacteria rapidly liberates ammonia with the formation of fumaric acid. It is known that the latter slowly gives rise to malic acid (in presence of bacteria); hence it follows that aspartic acid presents an instance of an a-amino-acid proceeding to the corresponding hydroxy-acid via the unsaturated acid. Whether this is true in the animal body or with plant tissues still remains to be determined. Raistrick [1917] showed that in the case of organisms of the coli-typhosus group histidine produces the corresponding unsaturated acid, urocanic acid. With aspartic acid, it will be shown, a similar reaction occurs reversibly, the following equilibrium being established: 1-aspartic acid = fumaric acid + ammonia, and it is possible to obtain the equilibrium constant of this reaction. It is by no means a general phenomenon, however, that an a-amino-acid, in contact with B. coli, gives up ammonia to form the corresponding unsaturated acid. Under conditions such that aspartic acid readily loses ammonia to form fumaric acid, no liberation of ammonia has been observed to occur from 36-2
1. The Introduction (pp. 67–73) describes the course of infant mortality in England and Wales over the past century, and critically reviews arguments advanced to prove that variations in the infant mortality rate (i.m.) are caused by genetic differences with respect to viability.2. The i.m. in county boroughs shows a 2-yearly cycle of variability, affecting places with high mortalities.3. We have devised and tested various social indices and have selected five which gave the highest joint covariance with infant mortality in county boroughs during the 11 years 1928–38. These indices are:H, percentage of families living more than 1 person per room.U, percentage of men unemployed.P, percentage of occupied males in the Registrar-General's Social Classes IV and V.F, percentage of women employed on manufacturing processes.L, latitude.4. We have computed multiple regression equations involving i.m. and the five indices for each of the 11 years, and two summarizing equations. The regressions plus sampling variance account for about 80% of the total variance in infant mortality. The regression is linear.5. Latitude does not affect infant mortality in Class I. For this and other reasons we regard the latitude effect as expressing miscellaneous poverty indices omitted from our equations.6. The regression equations enable us to divide the population into various strata with characteristic average infant mortality rates. These include:‘Better off’ (all poverty indices = 0) i.m.=23·1Overcrowded poor i.m. = 108Unemployed overcrowded poor i.m. = 153Babies whose mothers work in industry suffer an additional mortality risk of at least 35 per 1000, and possibly more. The figure 23·1 is the i.m. rate that would prevail if our five poverty symptoms could be eliminated.7. In county boroughs two-thirds of infant deaths would be avoided by the abolition of conditions defined by our indices. Of the preventable deaths, one-third are associated with overcrowding, one-quarter with low-paid occupations, one-fifth with unemployment, and one-eighth with industrial employment of women. In England and Wales, over 250,000 deaths in 11 years, about 63% of the total, can be attributed to adverse social conditions.We have to thank the Rockefeller Foundation for a personal grant to one of us (J. W.) out of an allocation for research work in Prof. Lancelot Hogben's Department, and the Halley Stewart Trust for a grant for mechanical computing equipment. Our thanks are also due to the various members of the Zoology Department in the University of Birmingham who assisted in computing at various times, and especially to Prof. Hogben for his unfailing interest, advice and support.
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