819 research outputs found
Creole women traders in the nineteenth century
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
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
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
Call number: LD2668 .T4 1930 W4
Differences in intelligence and their relation to position in family
Thesis (Ed.M.)--Boston University This item was digitized by the Internet Archive
Survey of the savings banks of Boston
Thesis (M.B.A.)--Boston Universit
The Need for American Ethnic Studies at Predominantly White Institutions (I): African American and Native American Studies
This session will provide a straightforward account of what ethnic studies is and the current state of ethnic studies
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