The low energy expansion of the one-loop type II superstring amplitude

The one-loop four-graviton amplitude in either of the type II superstring theories is expanded in powers of the external momenta up to and including terms of order s^4 log s R^4, where R^4 denotes a specific contraction of four linearized Weyl tensors and s is a Mandelstam invariant. Terms in this series are obtained by integrating powers of the two-dimensional scalar field theory propagator over the toroidal world-sheet as well as the moduli of the torus. The values of these coefficients match expectations based on duality relations between string theory and eleven-dimensional supergravity.Comment: harvmac (b), 25 pages, 3 eps figures. v2: Factors of 2 corrected. Conclusion unchange

Will the new $100 bill decrease counterfeiting?

A current U.S. policy is to introduce a new style of currency that is harder to counterfeit, but not immediately to withdraw from circulation all of the old-style currency. This policy is analyzed in a random matching model of money, and its potential to decrease counterfeiting in the long run is shown. For various parameters of the model, three types of equilibria are found to occur. In only one does counterfeiting continue at its initial high level. In the other two, both genuine and counterfeit old-style money go out of circulation—immediately in one and gradually in the other. There are objectives and expectations that can reasonably be imputed to policymakers, under which the policy that they have chosen can make sense.Money

The inter- and intra-observer reliability of a locomotion scoring scale for sheep

A seven point locomotion scoring scale, ranging from 0 = normal locomotion to 6 = unable to stand or move, has been developed. To test the between and within observer reliability of the scale, 65 movie clips of sheep with normal and varying degrees of abnormal locomotion were made. Three observers familiar with sheep locomotion were trained to read the movie clips. Thirty clips were randomly selected and used to test between and within observer agreement. There was high inter-(intra-class correlation coefficient [ICC] = 0.93, weighted kappa [κw] = 0.93) and intra-(ICC = 0.90, κw = 0.91) observer reliability, with no evidence of observer bias. The main between score differences were for scores 0 (normal) and 1 (uneven posture and shortened stride but no head movement). The results indicate that the locomotion scoring scale using groups of defined observations for each point on the scale was reliable and may be a useful research tool to identify and monitor locomotion in individual sheep when used by trained observers

Remarks on the Classical Size of D-Branes

We discuss different criteria for `classical size' of extremal Dirichlet p-branes in type-II supergravity. Using strong-weak coupling duality, we find that the size of the strong-coupling region at the core of the (p<3)-branes, is always given by the asymptotic string scale, if measured in the weakly coupled dual string metric. We also point out how the eleven-dimensional Planck scale arises in the classical 0-brane solution, as well as the ten-dimensional Planck scale in the D-instanton solution.Comment: 8 pp, harvma

D-instanton partition functions

Duality arguments are used to determine D-instanton contributions to certain effective interaction terms of type II supergravity theories in various dimensions. This leads to exact expressions for the partition functions of the finite N D-instanton matrix model in d=4 and 6 dimensions that generalize our previous expression for the case d=10. These results are consistent with the fact that the Witten index of the T-dual D-particle process should only be non-vanishing for d=10.Comment: 20 pages, harvmac, typos corrected, reference adde

Supersymmetry Constraints on Type IIB Supergravity

Supersymmetry is used to derive conditions on higher derivative terms in the effective action of type IIB supergravity. Using these conditions, we are able to prove earlier conjectures that certain modular invariant interactions of order alpha' **3 relative to the Einstein-Hilbert term are proportional to eigenfunctions of the Laplace operator on the fundamental domain of SL(2,Z). We also discuss how these arguments generalize to terms of higher order in alpha', as well as to compactifications of supergravity.Comment: 31 pages, harvmac (b); minor correction

Formulating Light Cone QCD on the Lattice

We present the near light cone Hamiltonian $H$ in lattice QCD depending on the parameter $\eta$, which gives the distance to the light cone. Since the vacuum has zero momentum we can derive an effective Hamiltonian $H_{eff}$ from $H$ which is only quadratic in the momenta and therefore solvable by standard methods. An approximate ground state wave functional is determined variationally in the limit $\eta \to 0$.Comment: 48 pages, 8 figure

The Spectral Evolution of Transient Anomalous X-ray Pulsar XTE J1810--197

(Abridged) We present a multi-epoch spectral study of the Transient Anomalous X-ray Pulsar XTE J1810-197 obtained with the XMM X-ray telescope. Four observations taken over the course of a year reveal strong spectral evolution as the source fades from outburst. The origin of this is traced to the individual decay rates of the pulsar's spectral components. A 2-T fit at each epoch requires nearly constant temperatures of kT=0.25 & 0.67 keV while the component luminosities decrease exponentially with tau=900 & 300d, respectively. One possible interpretation is that the slowly decaying cooler component is the radiation from a deep heating event that affected a large fraction of the crust, while the hotter component is powered by external surface heating at the foot-points of twisted magnetic field lines, by magnetospheric currents that are decaying more rapidly. The energy-dependent pulse profile of XTE J1810-197 is well modeled at all epochs by the sum of a sine and triangle function. These profiles peak at the same phase, suggesting a concentric surface emission geometry. The spectral and pulse evolution together argue against the presence of a significant ``power-law'' contribution to the X-ray spectrum below 8 keV. The extrapolated flux is projected to return to the historic quiescent level, characterized by an even cooler blackbody spectrum, by the year 2007.Comment: 12 pages, 6 Figures, Latex, emulateapj. To appear in the Astrophysical Journa