On the smoothness of static multi-black hole solutions of higher-dimensional Einstein-Maxwell theory

Previous work has shown that static multi-black hole solutions of higher-dimensional Einstein-Maxwell theory do not possess smooth horizons. We show that the lack of smoothness is worse than previously demonstrated. We consider solutions describing multiple black holes on a common axis. In five dimensions, the metric is generically twice, but not three times, continuously differentiable at the horizon. The Maxwell field is generically continuous, but not differentiable, at the horizon. In more than five dimensions, the metric is once, but not twice, continuously differentiable, and there is a parallely-propagated curvature singularity at the horizon. The Maxwell field strength is again continuous, but not differentiable, at the horizon.Comment: 19 pages; minor correction

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

Estate Taxes, Life Insurance, and Small Business

One criticism of the estate tax is that it prevents the owners of family businesses from passing their enterprises to their children. The problem is that it may be difficult to pay estate taxes without liquidating the business. A natural question is why individuals with such concerns do not purchase enough life insurance to meet their estate tax liabilities. This paper examines whether and how people use life insurance to deal with the estate tax. We find that, other things being the same, business owners purchase more life insurance than other individuals. However, on the margin, their insurance purchases are less responsive to estate tax considerations and they are less likely to have the wherewithal to meet estate tax liabilities out of liquid assets plus insurance.

The range of the tangential Cauchy-Riemann system on a CR embedded manifold

We prove that every compact, pseudoconvex, orientable, CR manifold of \C^n, bounds a complex manifold in the $C^\infty$ sense. In particular, the tangential Cauchy-Riemann system has closed range

Evanescent Black Holes

A renormalizable theory of quantum gravity coupled to a dilaton and conformal matter in two space-time dimensions is analyzed. The theory is shown to be exactly solvable classically. Included among the exact classical solutions are configurations describing the formation of a black hole by collapsing matter. The problem of Hawking radiation and backreaction of the metric is analyzed to leading order in a $1/N$ expansion, where $N$ is the number of matter fields. The results suggest that the collapsing matter radiates away all of its energy before an event horizon has a chance to form, and black holes thereby disappear from the quantum mechanical spectrum. It is argued that the matter asymptotically approaches a zero-energy ``bound state'' which can carry global quantum numbers and that a unitary $S$-matrix including such states should exist.Comment: 14 page

Solid State Physics

Contains research objectives

Solid State Physics

Contains research objectives