819 research outputs found

    Creole women traders in the nineteenth century

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    African Studies Center Working Paper No. 27This paper focuses on how the Sierra Leone women organized their West African trade and how they responded to the special obstacles faced by female traders. It pays particular attention to the Liberated African women and follows their progress until the end of the nineteenth century

    Newman-Penrose quantities as valuable tools in astrophysical relativity

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    In this talk I will briefly outline work in progress in two different contexts in astrophysical relativity, i.e. the study of rotating star spacetimes and the problem of reliably extracting gravitational wave templates in numerical relativity. In both cases the use of Weyl scalars and curvature invariants helps to clarify important issues.Comment: 3 pages. Proceedings of 16th SIGRAV conference, Vietri, Italy, September 200

    Rotating neutron stars: an invariant comparison of approximate and numerical spacetime models

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    We compare three different models of rotating neutron star spacetimes: the Hartle-Thorne (HT) slow-rotation approximation at second order in rotation, the exact analytic vacuum solution of Manko et al. and a numerical solution of the full Einstein equations. We integrate the HT structure equations for five representative equations of state. Then we match the HT models to numerical solutions of the Einstein equations, imposing that the mass and angular momentum of the models be the same. We estimate the limits of validity of the HT expansion computing relative errors in the spacetime's quadrupole moment Q and in the ISCO radii. We find that ISCO radii computed in the HT approximation are accurate to better than 1%, even for the fastest observed ms pulsar. At the same rotational rates the accuracy on Q is of order 20%. In the second part of the paper we focus on the exterior vacuum spacetimes. We introduce a physically motivated `quasi-Kinnersley' Newman-Penrose frame. In this frame we evaluate the speciality index S, a coordinate-independent quantity measuring the deviation of each model from Petrov Type D. On the equatorial plane this deviation is smaller than 5%, even for the fastest rotating models. Our main conclusion is that the HT approximation is very reliable for most astrophysical applications.Comment: 19 pages, 9 figures, accepted in MNRAS; improved presentation, some new analytical results in Section 5.

    General and specific factors in the 1929-30 K.S.A.C. freshman tests

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    Call number: LD2668 .T4 1930 W4

    Differences in intelligence and their relation to position in family

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

    Survey of the savings banks of Boston

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    Thesis (M.B.A.)--Boston Universit

    The Need for American Ethnic Studies at Predominantly White Institutions (I): African American and Native American Studies

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    This session will provide a straightforward account of what ethnic studies is and the current state of ethnic studies
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