Subharmonic resonance

Thesis (M.A.)--Boston University, 1949. This item was digitized by the Internet Archive

An analysis and extension of Eddington's unified theory of physics

Thesis (Ph.D.)--Boston UniversityThis thesis is divided into three parts. In the first part Eddington's algebra of E-numbers is outlined and the Dirac matrices are introduced. At this point .it becomes possible to relate specific entities that the two men treat in common. In particular, the derivation of the interchange operator from the point of view of wave tensor calculus is given in full. The reason for this method of treatment is that Eddington's interchange operator is more general than Dirac's, since it contains Dirac's interchange operator as one factor. The additional factor in Eddington's operator helps to form the basis of his nuclear theory. With the introduction of Lorentz rotations it becomes possible to show that many of the E-numbers have their exact counterpart in the work of Dirac. Part Two deals with certain general relationships which are shown to exist between the wave tensor calculus and the bra and ket vector algebra. Tho Heisenberg and Schrödinger formulations are presented. against the more general background or Dirac's algebra. Procedures are then set up to relate the bra and ket vectors to Eddington's wave vectors. Within the wave tensor algebra it is possible to build wave tensors of higher order from a group of wave vectors. One can, in turn, relate the elements of a second-rank wave tensor with a vector, and the element of a fourth-rank wave tensor with a second-rank tensor. This means that Dirac's bra and ket vectors can be related to a second-rank tensor. This is illustrated through the tenaors of electromagnetic theory and the Einstein law of gravitation. The purpose of Part Two is to show the tremendous scope possessed by the E-numbers. Part Three contains a more general type of discussion. Here, for example, the concept of an observable ia scrutinized from both Dirac's and Eddington's point of view. Although at first they look entirely different, they can be shown to be compatible. Eddington's argument for an absolute standard of length is also discussed. Here the particular application of Eddington's concept of a basic uncertainty in position appears. This argument applies to the field of quantum electrodynamics when one deals with an electron of zero dimensions. If the basic uncertainty in position is of the order of 10^-13 cm, then distances of less than this value cease to have physical significance, as their measurements cannot be taken. This helps to remove certain of the divergences inherent in a point particle theory. A step by step analysis leading to Eddington's exclusion principle is given, starting from the Pauli exclusion principle, because it gives insight as to the vantage point from which Eddington views physical theory

Cohort Profile: Burden of Obstructive Lung Disease (BOLD) study

The Burden of Obstructive Lung Disease (BOLD) study was established to assess the prevalence of chronic airflow obstruction, a key characteristic of chronic obstructive pulmonary disease, and its risk factors in adults (≥40 years) from general populations across the world. The baseline study was conducted between 2003 and 2016, in 41 sites across Africa, Asia, Europe, North America, the Caribbean and Oceania, and collected high-quality pre- and post-bronchodilator spirometry from 28 828 participants. The follow-up study was conducted between 2019 and 2021, in 18 sites across Africa, Asia, Europe and the Caribbean. At baseline, there were in these sites 12 502 participants with high-quality spirometry. A total of 6452 were followed up, with 5936 completing the study core questionnaire. Of these, 4044 also provided high-quality pre- and post-bronchodilator spirometry. On both occasions, the core questionnaire covered information on respiratory symptoms, doctor diagnoses, health care use, medication use and ealth status, as well as potential risk factors. Information on occupation, environmental exposures and diet was also collected

David Pocock's contributions and the legacy of Leavis

David Pocock (1928-2007) co-founded this journal with Louis Dumont, and it is easy to assume that they were intellectually more 'like-minded' than we believe was really the case. In the first part of this appreciation, we offer some biographical and intellectual context for Pocock's career. In the second, we identify the principal ways in which his sociological project did converge with Dumont's and the respects in which it seems fundamentally different. Both were deeply influenced by Evans-Pritchard; but much of their difference is explained, we suggest, by Pocock's prior loyalty to the teachings of the literary critic, F.R. Leavis. For good or ill, Pocock's more reflexive preoccupations and his concern with the moral complexity of social life chime better with, and indeed anticipate, subsequent theoretical trends in the discipline

European Atlas of Forest Tree Species

The European Atlas of Forest Tree Species is the first comprehensive publication of such a unique and essential environmental resource, that is, our trees. Leading scientists and forestry professionals have contributed in the many stages of the production of this atlas, through the collection of ground data on the location of tree species, elaboration of the distribution and suitability maps, production of the photographic material and compilation of the different chapters. The European Atlas of Forest Tree Species is both a scientific publication, in which researchers and forest specialists can find rigorous and up-to-date information on the many tree species of our forests, and a publication suited for education and the dissemination of information about the richness of our forests to our generation and future generations. Trees, as all other forms of life, adapt to the conditions in which they live. This adaptation is reflected in the shape of their leaves, their seeds, and their strategy for dissemination and expansion. Each chapter of the Atlas presents, in addition to the description of each tree species, high quality graphics and photographs showing the climatic preferences and singularities of the different species of trees