Chiral Green's Functions in Superconformal Field Theory

By solving the Ward identities in a superconformal field theory we find the unique three-point Green's functions composed of chiral superfields for N = 1,2,3,4 supersymmetry. We show that the N=1 four-point function with R-charge equal to one is uniquely determined by the Ward identities up to the specification of four constants. We discuss why chiral Green's functions above three-points, with total R-charge greater than N, are not uniquely determined.Comment: 32 pages, no figures, LaTeX2e forma

High impact activities in parks: best management practice and future research

Off-road driving, horseriding, rock climbing and similar activities can be lucrative for tour operators and important for local recreational groups, but contentious for management of national parks and protected areas, both because of safety and liability and because of potentially high environmental impacts. These include spreading weeds and pathogens, starting fires and crushing bird nests on beaches, amongst many others. In Australia as elsewhere, off-road vehicles and horses are allowed only in some places in some parks, and often only under permit. We have very little reliable scientific information to-date on just how serious these impacts may be, and on how well they might be managed through minimal-impact practices such as vehicle washdowns, stockfeed processing and seasonal closures. Such information can only be obtained through site specific ecological studies of the plants, animals and watercourses likely to be affected, differentiating tourism impacts from natural causes and fluctuations. This report examines management strategies for these activities worldwide and in Australia. Suggestions for best management practice and future research agendas are set

Spiral Structure Based Limits on the Disk Mass of the Low Surface Brightness Galaxies UGC 6614 and F568-6

Upper limits for the disk mass-to-light ratios for the low surface brightness galaxies UGC 6614 and F568-6 (Malin 2) are estimated by considering the minimum velocity perturbations in the HI velocity field that should result from the spiral structure observed in the R band images. The weak observed response in the $\phi$ velocity component limits the mass-to-light ratios of the disk within a scale length to M/L <~ 3 and 6 for UGC 6614 for F568-6 respectively (in solar units) based upon azimuthal variations observed in the R band images. These limits are sufficiently strong to require a significant dark matter component even in the central regions of these galaxies. Our limits furthermore imply that this dark matter component cannot be in the form of a cold disk since a cold disk would necessarily be involved in the spiral structure. However, a more massive disk could be consistent with the observations because of a non-linear gas response or if the gas is driven by bar-like distortions instead of spiral structure. To produce the large observed arm/interarm HI density variations it is likely that the spiral arm potential perturbation is sufficiently strong to produce shocks in the gas. For a forcing that is greater than 2% of the axisymmetric force, M/L >~ 1 is required in both galaxies in the outer regions. These lower limits imply that the stellar surface density is at least of the same order as the gas surface density. This is consistent with the large scale morphology of the spiral structure, and the stability of the gas disk, both which suggest that a moderate stellar component is required to produce the observed spiral structure. (Shortened abstract)Comment: AAS Latex, Postscript and jpeg Figures, Accepted for publication in A

Pilot Sensitivity to Simulator Flight Dynamics Model Formulation for Stall Training

A piloted simulation study was performed in the Cockpit Motion Facility at the National Aeronautics and Space Administration Langley Research Center. The research was motivated by the desire to reduce the commercial transport airplane fatal accident rate due to in-flight loss of control. The purpose of this study, which focused on a generic T-tail transport airplane, was to assess pilot sensitivity to flight dynamics model formulation used during a simulator stall recognition and recovery training/demonstration profile. To accomplish this, the flight dynamics model was designed with many configuration options. The model options were based on recently acquired static and dynamic stability and control data from sources that included wind tunnel, water tunnel, and computational fluid dynamics. The results, which are specific to a transport airplane stall recognition and recovery guided demonstration scenario, showed the two most important aerodynamic effects (other than stick pusher) to model were stall roll- off and the longitudinal static stability characteristic associated with the pitch break

Vacuum Photon Splitting in Lorentz-Violating Quantum Electrodynamics

Radiative corrections arising from Lorentz violation in the fermion sector induce a nonzero amplitude for vacuum photon splitting. At one loop, the on-shell amplitude acquires both CPT-even and CPT-odd contributions forbidden in conventional electrodynamics.Comment: 4 pages, minor wording changes, references added, accepted in Physical Review Letter