1,806 research outputs found

    The dynamics of cryosorption pumping

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    Dynamics of cryosorption pumping of air, argon, and hydrogen by activated charcoa

    Fidelity for imperfect postselection

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    We describe a simple measure of fidelity for mixed state postselecting devices. The measure is most appropriate for postselection where the task performed by the output is only effected by a specific state.Comment: 8 Pages, 8 Figure

    Magnetic activity on AB Doradus: Temporal evolution of starspots and differential rotation from 1988 to 1994

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    Surface brightness maps for the young K0 dwarf AB Doradus are reconstructed from archival data sets for epochs spanning 1988 to 1994. By using the signal-to-noise enhancement technique of Least-Squares Deconvolution, our results show a greatly increased resolution of spot features than obtained in previously published surface brightness reconstructions. These images show that for the exception of epoch 1988.96, the starspot distributions are dominated by a long-lived polar cap, and short-lived low to high latitude features. The fragmented polar cap at epoch 1988.96 could indicate a change in the nature of the dynamo in the star. For the first time we measure differential rotation for epochs with sufficient phase coverage (1992.05, 1993.89, 1994.87). These measurements show variations on a timescale of at least one year, with the strongest surface differential rotation ever measured for AB Dor occurring in 1994.86. In conjunction with previous investigations, our results represent the first long-term analysis of the temporal evolution of differential rotation on active stars.Comment: accepted by MNRAS 18 pages 18 figure

    Forestry Benefits from Land Use Planning

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    Land planning has become in our country the proper thing to do. Planning for land use is not a new procedure in many sections of the nation. The name only is new. We have adopted various means of designating specifically the use of areas of rural land. For many years there have been areas quarantined to prevent spread of animal or plant diseases; game preserves are older than some of the states; herd district areas were early formulated on the open range; more than half a century ago areas of land were set aside for their natural phenomena and reserved for public use; and, of course, all of us are accustomed to the forest areas being established for the growing of timber

    Essays On Labor And Corporate Finance

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    This dissertation consists of two chapters that relate labor issues and corporate finance. In the first chapter, I investigate the impact of restricting labor mobility on two components of growth: entrepreneurship and capital investment. To identify the mechanism, I combine LinkedIn\u27s database of employment histories with staggered changes in the enforceability of non-compete agreements that come mostly from state supreme court rulings. Stronger enforceability leads to a substantial decline in employee departures, especially in knowledge-intensive occupations, and reduces entrepreneurship in corresponding sectors. However, these shocks increase the investment rate at existing knowledge-intensive firms. I estimate a state of median size gains $50 million in capital investment from publicly-held knowledge-intensive firms, but loses almost 200 small firms entering knowledge-intensive sectors. In the second chapter, I explore a specific mechanism through which corporate social responsibility (CSR), and in particular pro-employee policies, may benefit companies. I propose that socially responsible behavior generates public goodwill toward the firm, which can be redeemed when the company needs public approval, such as when applying for public contracts. To provide causal support for this mechanism, I use the staggered state passage of Other Constituency (OC) laws, which allow directors to orient policies toward non-shareholder constituents. Following the passage of OC laws, employee safety and health measures systematically improve, indicating more employee-oriented behavior. At the same time, firms incorporated in these states systematically become more likely to obtain public contracts and obtain contracts of higher value

    Values Examination in Art Curricula Construction from Owatonna to Today

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    In developing curricula and educational policy, arts educators must participate with students, parents and other members of the community in dialectic processes of values examination. Failure to do so can often result in the development of curricula and policies which send unintended and unacceptable signals about the purposes and importance of the arts in our society. A critical analysis of the Owatonna Art Education Project (1933- 38), together with a review of current curricula and educational policies indicate a need for the use of these processes, arts educators may be unaware of the signals that they are sending through curricula and policy

    Retrodiction as a tool for micromaser field measurements

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    We use retrodictive quantum theory to describe cavity field measurements by successive atomic detections in the micromaser. We calculate the state of the micromaser cavity field prior to detection of sequences of atoms in either the excited or ground state, for atoms that are initially prepared in the excited state. This provides the POM elements, which describe such sequences of measurements.Comment: 20 pages, 4(8) figure

    Spurious 'active longitudes' in parametric models of heavily spotted eclipsing binaries

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    In this paper, size distributions of starspots extrapolated from the case of the Sun, are modelled on the eclipsing binary SV Cam to synthesise images of stellar photospheres with high spot filling factors. These spot distributions pepper the primary's surface with spots, many of which are below the resolution capabilities of eclipse mapping and Doppler imaging techniques. The lightcurves resulting from these modelled distributions are used to determine the limitations of image reconstruction from photometric data. Surface brightness distributions reconstructed from these lightcurves show distinctive spots on the primary star at its quadrature points. It is concluded that two-spot modelling or chi-squared minimisation techniques are more susceptible to spurious structures being generated by systematic errors, arising from incorrect assumptions about photospheric surface brightness, than simple Fourier analysis of the light-curves.Comment: 5 pages, 18 figures, MNRAS in pres

    An evaluation of the New Choices for Youth Right Here Project in Newham Sixth Form College

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    Right Here Newham is a five year project that is part of the national Right Here initiative funded by Paul Hamlyn Foundation and managed jointly by the Foundation and the Mental Health Foundation (2009 -2014). The initiative aims to develop new approaches to supporting the mental health and wellbeing of young people aged 16 to 25 years by early intervention and the participation of young people in all aspects of project development and manage is integral to its approach. The evaluation consisted of making observations of the drama classes and Men’s group discussions in the final few weeks of the project, and interviewing the students involved. It had been hoped to identify and interview students who had been involved in the earlier work of the project in the college but this was not possible. The evaluation aims to capture the detail of how the project worked and to give some indication of how the participants felt about the project and the impact it was having on their lives

    Constraining the Circumbinary Envelope of Z CMa via imaging polarimetry

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    Z CMa is a complex binary system, composed of a Herbig Be and an FU Ori star. The Herbig star is surrounded by a dust cocoon of variable geometry, and the whole system is surrounded by an infalling envelope. Previous spectropolarimetric observations have reported a preferred orientation of the polarization angle, perpendicular to the direction of a large, parsec-sized jet associated with the Herbig star. The variability in the amount of polarized light has been associated to changes in the geometry of the dust cocoon that surrounds the Herbig star. We aim to constrain the properties of Z CMa by means of imaging polarimetry at optical wavelengths. Using ExPo, a dual-beam imaging polarimeter which operates at optical wavelengths, we have obtained imaging (linear) polarimetric data of Z CMa. Our observations were secured during the return to quiescence after the 2008 outburst. We detect three polarized features over Z CMa. Two of these features are related to the two jets reported in this system: the large jet associated to the Herbig star, and the micro-jet associated to the FU Ori star. Our results suggest that the micro-jet extends to a distance ten times larger than reported in previous studies. The third feature suggests the presence of a hole in the dust cocoon that surrounds the Herbig star of this system. According to our simulations, this hole can produce a pencil beam of light that we see scattered off the low-density envelope surrounding the system.Comment: Accepted for publication in A\&
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