Colin Clark (1905-89) Economist and Agricultural Economist

In 1986 the Oxford University Institute of Agricultural Economics was amalgamated into Queen Elizabeth House. The Institute, which came into being in 1913, achieved considerable distinction for its work on the problems of British agriculture under the Directorships of C.S.Orwin and A.W. Ashby. The third Director (1953-69) was of a somewhat different stamp. Colin Clark (1905-89), though without formal training in economics, had established himself as a pioneer of national accounting techniques in the Cambridge of the 1930s (he was mentioned in Keynes' General Theory) and progressed to write one of the classic studies of growth (Conditions of Economic Progress). His name appeared prominently in the Meier and Seers book on 'Pioneers of Development' and there have been many other testaments to his international reputation. The Oxford period witnessed famous controversies on population and food supply, the publication (with Margaret Haswell) of 'The Economics of Subsistence Agriculture', and much other work on a wide range of subjects by no means confined to agricultural issues. The essay which is reprinted below originally appeared in the Italian journal Rivista di Economia Agraria (June 1995) as part of a series on major figures in agricultural economics, and was presented at an Agricultural Economics Society conference (Edinburgh, 1998). It is also the basis for a shorter entry in the Dictionary of National Biography, 1981-90 Supplement. The writer spent a considerable part of his early career as one of Colin Clark's research assistants. A number of people have been kind enough to suggest that the essay should have greater accessibility.

Secondary dispersion of sulphur from sulphide deposits in the Notre Dame Bay area, Newfoundland

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Biomagnetic methodologies for the noninvasive investigations of the human brain (Magnobrain)

Magnetoencephalography (MEG) non-invasively infers the distribution of electric currents in the brain by measuring the magnetic fields they induce. Its superb spatial and temporal resolution provides a solid basis for the `functional imaging¿ of the brain provided it is integrated with other brain imaging techniques. MAGNOBRAIN is an applied research project that developed tools to integrate MEG with MRI and EEG. These include: (1) software for MEG oriented MRI feature extraction; (2) the Brain Data Base (BDB) which is a reference library of information on the brain used for more realistic and biologically meaningful functional localisations through MEG and EEG; and (3) a database of normative data (age and sex matched) for the interpretation of MEG. It is expected that these tools will evolve into a medical informatics environment that will aid the planning of neurosurgical operations as well as contribute to the exploration of mental function including the study of perception and cognition

Viewpoint: Education in older America

The graying of America is a phrase increasingly used by researchers, educators, social service and health professionals, politicians, and policy makers at all levels of government

Oscillatory solutions in conservation laws related to nonexistence of weak self-similar Riemann solutions

We study Riemann solutions of inviscid systems of conservation laws obtained as a viscous limit of an associated parabolic system. This limit depends on the positive definite viscosity matrix. Specifically, we consider Riemann problems with shock initial data, i.e., the initial data for which the right and left states correspond to a Lax admissible shock. We are particularly interested in what happens with a Riemann solution if this shock does not admit a viscous profile due to the presence of a Hopf bifurcation and limit cycles in the dynamical system associated to the viscous entropy criterion;We focus our study on two classes of models: the shallow water equations and a three-phase flow model arising in petroleum engineering. For these models with Riemann data in the strictly hyperbolic region, it is proved that there exists no weak self-similar Riemann solution. Instead, numerical simulations provide solutions exhibiting continuously generated oscillations. We prove that the limit of these oscillatory solutions, as the viscosity goes to zero, satisfies the system of conservation laws in a measure-valued sense. We conjecture that in the three-phase flow model this solution corresponds to interspersing of different phases

A note on partial vertical integration

A simple model is constructed to show how partial vertical integration may emerge as an equilibrium market structure in a world characterized by rationing, differences in the reservation prices of buyers, and in the risk attitudes of buyers and sellers. The buyers with the high reservation prices turn out to be vertically integrated