Conflicts between animals of the same species usually are of “limited war” type, not causing serious injury. This is often explained as due to group or species selection for behaviour benefiting the species rather than individuals. Game theory and computer simulation analyses show, however, that a “limited war” strategy benefits individual animals as well as the species.

The Logic of Animal Conflict

The contraction of Gaussian basis functions for use in molecular calculations is investigated by considering the effects of contraction on the energies and one‐electron properties of the water and nitrogen molecules. The emphasis is on obtaining principles which can be used to predict optimal contraction schemes for other systems without the necessity of such exhaustive calculations. Using these principles, contractions are predicted for the first‐row atoms.

Gaussian Basis Functions for Use in Molecular Calculations. III. Contraction of (10s6p) Atomic Basis Sets for the First‐Row Atoms

Infrared spectroscopy of proteins.

The major source of error in most ab initio calculations of molecular energies is the truncation of the one‐electron basis set. An open‐shell complete basis set (CBS) model chemistry, based on the unrestricted Hartree–Fock (UHF) zero‐order wave function, is defined to include corrections for basis set truncation errors. The total correlation energy for the first‐row atoms is calculated using the unrestricted Mo/ller–Plesset perturbation theory, the quadratic configuration interaction (QCI) method, and the CBS extrapolation. The correlation energies of the atoms He, Li, Be, B, C, N, O, F, and Ne, calculated using atomic pair natural orbital (APNO) basis sets, vary from 85.1% to 95.5% of the experimental correlation energies. However, extrapolation using the asymptotic convergence of the pair natural orbital expansions retrieves from 99.3% to 100.6% of the experimental correlation energies for these atoms. The total extrapolated energies (ESCF+Ecorrelation) are then in agreement with experiment to within ±0...

A complete basis set model chemistry. II. Open‐shell systems and the total energies of the first‐row atoms

fold thickness. A simple method of assessing quantitatively the fat content of the human body, which could be used not only in laboratories and in hospital, but in field studies and in general medical practice, would be invaluable. Methods in use at present, based on measurements of body density, body water or body potassium, can be applied only in the laboratory and usually to small numbers of subjects. Several previous papers have suggested relationships between one of the accepted methods of determining body fat and a simpler technique which could be widely applied. As early as 1921, Matiegka (1921) formulated an equation for calculating body fat from measurements of surface area and six skinfold thicknesses. Brotek & Keys (1951) were the first to use the relationship between skinfold thickness and body density for assessing fat content. The skinfolds chosen were not ideal and their formula has not been widely used. Pascale, Grossman, Sloane & Frankel (1956) in the USA produced an equation, and PaPizkovL (1961 a) in Czechoslovakia a nomogram, for predicting fat content from skinfold thicknesses. Steinkamp, Cohen, Gaffey, McKay, Bron, Siri, Sargent & Isaacs (196 j) gave predictive equations based on measurements of body circumferences and skinfold thicknesses on 167 subjects in California. The only comparable attempt on a British population, to our knowledge, is a study on twenty-four hospital patients, measurements being made of total body water and skinfold thickness (Fletcher, 1962). Information about a wide range of body types in population groups in Britain is required. The present paper describes a study on 105 young adults and 86 adolescents. By means of results from measurements by anthropometry including skinfold thicknesses and body density, an attempt has been made to formulate simple equations for the prediction of the quantity of fat in the body. The subjects were of varying body build-thin, intermediate, plump, but very few were obese.

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The assessment of the amount of fat in the human body from measurements of skinfold thickness

Reflection of light is a surface phenomenon—it is strongly dependent on the nature of the surface and can therefore be used to study surfaces. If the surface is flat and smooth, the nature of the reflection is called specular, i.e., mirrorlike, and obeys the simple law that the angle of incidence equals the angle of reflection.

Joseph G. Hoffman

Papers

Internal Reflection Spectroscopy

Physical Techniques in Biological Research

Advances in Biological and Medical Physics

Quantum Theory of Atoms, Molecules and the Solid State: A Tribute to John C. Slater

The Natural Radiation Environment