21,958 research outputs found

    On Sasaki-Einstein manifolds in dimension five

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    We prove the existence of Sasaki-Einstein metrics on certain simply connected 5-manifolds where until now existence was unknown. All of these manifolds have non-trivial torsion classes. On several of these we show that there are a countable infinity of deformation classes of Sasaki-Einstein structures.Comment: 18 pages, Exposition was expanded and a reference adde

    Nitrogen Chemistry Significant to Primordial Systems Semiannual Report, 1 Jul. - 31 Dec. 1966

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    Deoxygenation of benzoyl cyanide, studies of vinyl nitrenes and diene isocyanates, and other aspects of nitrogen chemistry significant to primordial biological system

    Elements of Design for Containers and Solutions in the LinBox Library

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    We describe in this paper new design techniques used in the \cpp exact linear algebra library \linbox, intended to make the library safer and easier to use, while keeping it generic and efficient. First, we review the new simplified structure for containers, based on our \emph{founding scope allocation} model. We explain design choices and their impact on coding: unification of our matrix classes, clearer model for matrices and submatrices, \etc Then we present a variation of the \emph{strategy} design pattern that is comprised of a controller--plugin system: the controller (solution) chooses among plug-ins (algorithms) that always call back the controllers for subtasks. We give examples using the solution \mul. Finally we present a benchmark architecture that serves two purposes: Providing the user with easier ways to produce graphs; Creating a framework for automatically tuning the library and supporting regression testing.Comment: 8 pages, 4th International Congress on Mathematical Software, Seoul : Korea, Republic Of (2014

    Unemployment and the UK Labour Market Before, During and After the Golden Age

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    During the ‘golden age’ of the 1950s and 1960s unemployment in Britain averaged 2 per cent. This was far lower than ever before or since and a number of hypotheses have been put forward to account for this unique period in labour market history. But there has been little attempt to isolate precisely how the determinants of wage setting and unemployment differed before, during and after the golden age. We estimate a two-equation model over the whole period from 1872 to 1999 using a newly constructed set of long-run labour market data. We find that the structure of real wage setting was different in the golden age, consistent with notions about the postwar consensus, but it did not result in wages that were significantly lower relative to productivity than during other eras. Rapid growth in productivity and world trade together with low interest rates did keep unemployment lower during the golden age than after the 1970s. But the key difference between the golden age and the periods before and after was shifts in labour demand that are not accounted for by any of the variables that are usually thought to determine the equilibrium unemployment rate

    Deoxygenation of organic nitrites

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    Organic nitrites deoxygenated in presence of tervalent phosphorus reagent

    Darwin-Lagrangian Analysis for the Interaction of a Point Charge and a Magnet: Considerations Related to the Controversy Regarding the Aharonov-Bohm and Aharonov-Casher Phase Shifts

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    The classical electromagnetic interaction of a point charge and a magnet is discussed by first calculating the interaction of point charge with a simple model magnetic moment and then suggesting a multiparticle limit. The Darwin Lagrangian is used to analyze the electromagnetic behavior of the model magnetic moment (composed of two oppositely charged particles of different mass in an initially circular orbit) interacting with a passing point charge. The changing mangetic moment is found to put a force back on a passing charge; this force is of order 1/c^2 and depends upon the magnitude of the magnetic moment. It is suggested that in the limit of a multiparticle magnetic toroid, the electric fields of the passing charge are screened out of the body of the magnet while the magnetic fields penetrate into the magnet. This is consistent with our understanding of the penetration of electromagnetic velocity fields into ohmic conductors. Conservation laws are discussed. The work corresponds to a classical electromagnetic analysis of the interaction which is basic to understanding the controversy over the Aharonov-Bohm and Aharonov-Casher phase shifts and represents a refutation of the suggestions of Aharonov, Pearle, and Vaidman.Comment: 33 page
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