The presence of fields with negative mass–squared typically leads to some form of instability in standard field theories. The observation that, at least in the light–cone gauge, strings propagating… (More)

This paper considers the spacetimes describing pp-waves propagating on extremal non-dilatonic branes. It is shown that an observer moving along a geodesic will experience infinite curvature at the… (More)

OBJECTIVES
The Emergency Severity Index version 4 (ESI v.4) is a triage system, which demonstrates reliability in adult populations, however, it has not been extensively studied in pediatrics. The… (More)

We argue that the trace structure of the non–abelian Born–Infeld action can be fixed by demanding that the action be linearised by certain energy– minimising BPS–like configurations. It is shown how… (More)

We comment on the recent papers by Costa et al and Emparan, which show how one might generate supergravity solutions describing certain dielectric branes in ten dimensions. The “basic” such solutions… (More)

We discuss plane wave backgrounds of string theory and their relation to Gödel–like universes. This involves a twisted compactification along the direction of propagation of the wave, which induces… (More)

Up to overall harmonic factors, the D8-brane solution of the massive type IIA supergravity theory is the product of nine–dimensional Minkowski space (the worldvolume) with the real line (the… (More)

We attempt to settle the issue as to what is the correct non–abelian generalisation of the Born–Infeld action, via a consideration of the two–loop β–function for the non–abelian background gauge… (More)

Matrix string theory is equivalent to type IIA superstring theory in the light-cone gauge, together with extra degrees of freedom representing D-brane states. It is therefore the appropriate… (More)

Just as the single fluxbrane is quantum mechanically unstable to the nucleation of a locally charged spherical brane, so intersecting fluxbranes are unstable to various decay modes. Each individual… (More)