Algebraically special perturbations of the Schwarzschild solution in higher dimensions

We study algebraically special perturbations of a generalized Schwarzschild solution in any number of dimensions. There are two motivations. First, to learn whether there exist interesting higher-dimensional algebraically special solutions beyond the known ones. Second, algebraically special perturbations present an obstruction to the unique reconstruction of general metric perturbations from gauge-invariant variables analogous to the Teukolsky scalars and it is desirable to know the extent of this non-uniqueness. In four dimensions, our results generalize those of Couch and Newman, who found infinite families of time-dependent algebraically special perturbations. In higher dimensions, we find that the only regular algebraically special perturbations are those corresponding to deformations within the Myers-Perry family. Our results are relevant for several inequivalent definitions of "algebraically special".Comment: 23 pages, no figures. v2: references added; discussion improved; matches published versio

Following in Her Footsteps? Women's Choices of College Majors and Faculty Gender Composition

It is frequently asserted that a college's female undergraduate enrollment in the sciences and engineering can be increased by raising female representation on the faculties in these areas. Despite the widespread acceptance of this proposition, it does not appear to have been subjected to any kind of serious statistical analysis. In this paper, we assemble panel data from three rather different educational institutions, and use them to examine the relationship between the gender composition of the students in an academic department and the gender composition of its faculty at the time the students were choosing their majors. We find no evidence for the conventional view that an increase in the share of females on a department's faculty leads to an increase in its share of female majors.

Will the Real Excess Burden Please Stand Up? (Or, Seven Measures in Search of a Concept)

It is well understood that a tax which distorts relative prices generates a welfare cost or "excess burden" in addition to any associated transfer of resources, but there remains considerable controversy and confusion with respect to procedures for measuring this excess burden. The purpose of this paper is to clarify matters concerning what is one of the most basic concepts in welfare economics. We describe and evaluate a number of alternative conceptual experiments which might lie behind an excess burden calculation, showing how these notions can be represented graphically and algebraically and how they can be approximated numerically.

Tension is Dimension

We propose a simple universal formula for the tension of a D-brane in terms of a regularized dimension of the associated conformal field theory statespace.Comment: 18 pages, harvmac (b), one ref added, one typo fixe

Initial Experiences of Building Secure Access to Patient Confidential Data via the Internet

A project to enable health care professionals (GPs, practice nurses and diabetes nurse specialists) to access, via the Internet, confidential patient data held on a secondary care (hospital) diabetes information system, has been implemented. We describe the application that we chose to distribute (a diabetes register); the security mechanisms we used to protect the data (a public key infrastructure with strong encryption and digitally signed messages, plus a firewall); the reasons for the implementation decisions we made; the validation testing that we performed and the preliminary results of the pilot implementation

Trade studies for nuclear space power systems

As human visions of space applications expand and as we probe further out into the universe, our needs for power will also expand, and missions will evolve which are enabled by nuclear power. A broad spectrum of missions which are enhanced or enabled by nuclear power sources have been defined. These include Earth orbital platforms, deep space platforms, planetary exploration, and terrestrial resource exploration. The recently proposed Space Exploration Initiative (SEI) to the Moon and Mars has more clearly defined these missions and their power requirements. Presented here are results of recent studies of radioisotope and nuclear reactor energy sources, combined with various energy conversion devices for Earth orbital applications, SEI lunar/Mars rovers, surface power, and planetary exploration