Strict Theory Research Articles

Mesure absolue de l'Activité des radionuclides par la méthode des coïncidences β-γ etude d'une méthode de correction automatique des erreurs instrumentales

ABSOLUTE MEASUREMENT OF THE ACTIVITY OF RADIONUCLIDES BY THE β-γ COINCIDENCE METHOD. STUDY OF A METHOD FOR AUTOMATICALLY CORRECTING INSTRUMENT ERRORS After a consideration of the strict theory of the arrangement known as the live-time integrator, it is shown how this may be applied to coincidence measurements in order to ascertain the various counting losses due to the dead times of the two channels, whatever the nature of these dead times. It is likewise shown for two particular cases that the proposed method also allows corrections to be made for instrumental coincidences. The experimental study which follows the theoretical section enables us to confirm deductions drawn from theory in the case of non-cumulative dead times.

Performance, Purpose, and Permission

In this paper we attempt to formulate logical foundations for a theory of actions or performance. Human beings act in various ways, and their actions are intimately interrelated with their use of language. But precisely how actions and the use of language are interrelated is not very clear. One of the reasons is perhaps that we have no precise vocabulary in terms of which such interrelations may be handled. There is need for developing a systematic theory in which different kinds of actions may be discussed, contrasted, and compared. Then the various interrelations between actions and linguistic usage may perhaps be discussed rather more carefully and thoroughly than heretofore.Although much important preliminary work has been done in the analysis of actions, no one it seems has attempted to develop a strict logical theory for such analysis. A few tentative and programmatic steps were taken in the author's Toward a Systematic Pragmatics.1 Let us attempt here to improve those and take a few more. Any first attempts of this kind are of course fraught with difficulties. There inevitably will be some oversimplification or some overelaboration here or there. Ultimately of course we are interested in interrelating performance with various notions from syntax, semantics, and quantitative pragmatics.2 But this is not easy and only a few tentative suggestions toward such a development can be given here.In § 1 the distinction between action-kinds and action-events is drawn, and the character of the primitive or primitives needed for the theory of performance is discussed. In § 2 some further notions are then defined. Certain Rules of Performance are suggested in § 3. In § 4 there is discussion of the somewhat tenuous notion of acceptance as a basis for action. In § 5 the fundamental notions required for Parsons and Shils’ theory of social action is discussed briefly. In § 6 we attempt to define the two basic notions required in Leonard's recent papers concerning authorship and purpose. Finally, in § 7, the theory of performance is interrelated with von Wright's deontic logic, in which such notions as permission and obligation are considered.

Measurement of absolute viscosity by the falling sphere method

The Stokes formula for calculation of viscosity of a fluid fails badly when applied over the range 10 to 10,000 poises under ordinary conditions. Many viscosity data based on this relation which is valid only for a medium infinite in extent appear seriously in error. Several published corrections also fail but the Faxen relation, based on strict hydrodynamic theory, gives results in good agreement with values obtained by the improved capillary tube technique. Viscosity measurements on glycerol and “Viscous Oil” by the falling sphere method agree with values reported by Armour & Co., and by the Bureau of Standards over the range 7 to 3660 poises with maximum differences of less than 1%. Considerable practical as well as scientific interest attaches to the findings above since the requirements of apparatus and technique for measurement of absolute viscosities over a wide range with high accuracy are simple, inexpensive and generally available. The method is especially well suited for the range 10 poises and upwards and has been used in commercial research.

Relativistic Theory of the Photoelectric Effect. Part I. Theory of theK-Absorption of X-rays. Part II. Photoelectric Absorption of Ultragamma Radiation

Part I: A strict theory of the absorption of x-rays is developed on the basis of relativistic quantum electrodynamics. The theory is applied to the absorption of x-rays by a Dirac electron in the field of a nucleus. Corrections to the non-relativistic theory are appreciable only for heavy elements, where the present calculations give a $K$-discontinuity twenty percent smaller than the earlier ones. The agreement with experiment is not improved.Part II: The theory is applied to the calculation of the absorption of quanta whose energy is larger than the proper energy $m{c}^{2}$ of the electron. The cross section for absorption is here given approximately by $\ensuremath{\sigma}\ensuremath{\sim}2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}22}{Z}^{5}\ensuremath{\lambda}.$ This result is applied to account for the excess absorption over that predicted by the Klein-Nishina formula found experimentally for the gamma-rays of ThC\ensuremath{''} by Chao and Tarrant. The theory is in fairly good agreement with experiment for Cu, but disagrees violently with it for Pb. An examination of the approximations made in deriving and applying the theoretical result shows that they cannot have introduced this discrepancy. There is thus a definite conflict between electrodynamical theory and experiment.

Isostasy: A Critical Review

The underlying theory pertaining to the shape of the earth is briefly reviewed. The operations and results that have led to the theory of isostasy are given. Hopfner's recent inquiry into the problem is cited in which he has shown that by means of strict potential theory isostatic reductions are highly questionable, and, furthermore, that there is no need to postulate an isostatic state in order to account for gravity data. High points of geologic and seismologic data are also cited. The conclusion is that the theory of isostasy. rests upon a much more insecure foundation than has heretofore been supposed.

Paid-up Policies and Surrender Value

The principles upon which surrender values should be calculated are discussed at length in papers by Mr. Macfadyen (J. I. A., xvii, 381); Mr. Crisford (J. I. A., xxi, 301); and Mr. Fulford (J. I. A., xxxv, 199), but none of the methods proposed appear entirely satisfactory in practice, and I have therefore attempted to devise a scheme which shall not only give results in reasonable accordance with strict theory, but also prove simple and easily worked in its practical application.