1,721,681 research outputs found
Theory and Methods in Political Science
No full textA broad-ranging and pluralistic textbook which highlights the rich variety of approaches to studying politics. Written by an international team of experts, this fully revised fourth edition offers cutting-edge coverage from fundamental to contemporary issues. Integrating guides to further reading and clear examples of how research methods can be applied, it enables readers to feel confident about taking their study of politics forward.
An ideal foundation for study and research in political science, this textbook will be essential to students at any stage of their degree. It serves as core reading on undergraduate and postgraduate political analysis, theory and method courses. In addition, in demonstrating how independent research is undertaken in political science, the book allows students and early career researchers to begin thinking about formulating their own research agendas
Program refinement using a Universal Law : Language specification and prototype tool
No full textThe refinement calculus introduced by Back [Bac78], Morgan [Mor88a], Morris [Mor87] and others, combines specifications and programs into a single language and allows the development of a program from its specification to proceed in a number of small steps. The subject of this thesis is the definition of a specification and programming language based on the refinement calculus. A prototype tool has been developed from a formal language definition and simple examples are used to evaluate the language and tool.One difference from existing refinement systems is the use of a universal refinement law and a simple compiler-style tool, rather than many laws and interactive tools. Most of the benefits of the refinement calculus are maintained while the change of programming method is smaller than that required to use an interactive refinement system. The size of refinement steps can be varied and complex derivations of obvious developments avoided. Context is propagated automatically, allowing Back's generalisation of the familiar assignment statement to be used for specification.The use of subtypes and dependent types is another feature distinguishing this work. Subtypes and dependent types are integrated smoothly into the programming language and are shown to provide an accurate model of the runtime constraints of a programming language.Some have argued that formal methods are necessary to achieve safe programmable systems, but to date this has not been borne out by experience. However, achieving dependable software is expensive, suggesting that the use of formal methods should be directed towards reducing costs. This vision can be realised only by exploiting theories such as the refinement calculus pragmatically, aiming to enhance existing practices, with flexibility in matters such as the degree of rigour and the order of development steps. The work described in this thesis is intended to be a step in this direction.</p
Marsh David C. The changing social structure of England and Wales 1871-1951
No full textH. J. Marsh David C. The changing social structure of England and Wales 1871-1951. In: Population, 15ᵉ année, n°5, 1960. p. 915
Opening the 1 Hz axion window
No full textAbstract
An axion-like particle (ALP) with mass mϕ ∼ 10−15 eV oscillates with frequency ∼1 Hz. This mass scale lies in an open window of astrophysical constraints, and appears naturally as a consequence of grand unification (GUT) in string/M-theory. However, with a GUT-scale decay constant such an ALP overcloses the Universe, and cannot solve the strong CP problem. In this paper, we present a two axion model in which the 1 Hz ALP constitutes the entirety of the dark matter (DM) while the QCD axion solves the strong CP problem but contributes negligibly to the DM relic density. The mechanism to achieve the correct relic densities relies on low-scale inflation (mϕ ≲ Hinf ≲ 1 MeV), and we present explicit realisations of such a model. The scale in the axion potential leading to the 1 Hz axion generates a value for the strong CP phase which oscillates around
θ
¯
QCD
∼
10
−
12
, within reach of the proton storage ring electric dipole moment experiment. The 1 Hz axion is also in reach of near future laboratory and astrophysical searches
Black hole spin constraints on the mass spectrum and number of axionlike fields
No full textAstrophysical observations of spinning BHs, which span , can be used to exclude the existence of certain massive bosons via the superradiance phenomenon. In this work, we explore for the first time how these measurements can be used to constrain properties of statistical distributions for the masses of multiple bosonic fields. Quite generally, our methodology excludes {\rm ax}\gtrsim 30 for certain scenarios of interest realised approximately as mass distributions in M-theory, including the QCD axion, grand unified theories, and fuzzy dark matter
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