Manual for the Assessment, Location and Design of Reefwalking Activities

1985 Technical Report for the Great Barrier Reef Marine Park Authority. Financed by the Great Barrier Reef Marine Park Authority and undertaken with the co-operation of the School of Australian Environmental Studies, Griffith University

The Impact of Reef Walking at Hardy Reef

1984 report to Great Barrier Reef Marine Park Authority

Polarizing Bubble Collisions

We predict the polarization of cosmic microwave background (CMB) photons that results from a cosmic bubble collision. The polarization is purely E-mode, symmetric around the axis pointing towards the collision bubble, and has several salient features in its radial dependence that can help distinguish it from a more conventional explanation for unusually cold or hot features in the CMB sky. The anomalous "cold spot" detected by the Wilkinson Microwave Anisotropy Probe (WMAP) satellite is a candidate for a feature produced by such a collision, and the Planck satellite and other proposed surveys will measure the polarization on it in the near future. The detection of such a collision would provide compelling evidence for the string theory landscape.Comment: Published version. 15 pages, 8 figure

Primordial black holes in braneworld cosmologies: astrophysical constraints

In two recent papers we explored the modifications to primordial black hole physics when one moves to the simplest braneworld model, Randall--Sundrum type II. Both the evaporation law and the cosmological evolution of the population can be modified, and additionally accretion of energy from the background can be dominant over evaporation at high energies. In this paper we present a detailed study of how this impacts upon various astrophysical constraints, analyzing constraints from the present density, from the present high-energy photon background radiation, from distortion of the microwave background spectrum, and from processes affecting light element abundances both during and after nucleosynthesis. Typically, the constraints on the formation rate of primordial black holes weaken as compared to the standard cosmology if black hole accretion is unimportant at high energies, but can be strengthened in the case of efficient accretion.Comment: 17 pages RevTeX4 file with three figures incorporated; final paper in series astro-ph/0205149 and astro-ph/0208299. Minor changes to match version accepted by Physical Review

On Physical Equivalence between Nonlinear Gravity Theories

We argue that in a nonlinear gravity theory, which according to well-known results is dynamically equivalent to a self-gravitating scalar field in General Relativity, the true physical variables are exactly those which describe the equivalent general-relativistic model (these variables are known as Einstein frame). Whenever such variables cannot be defined, there are strong indications that the original theory is unphysical. We explicitly show how to map, in the presence of matter, the Jordan frame to the Einstein one and backwards. We study energetics for asymptotically flat solutions. This is based on the second-order dynamics obtained, without changing the metric, by the use of a Helmholtz Lagrangian. We prove for a large class of these Lagrangians that the ADM energy is positive for solutions close to flat space. The proof of this Positive Energy Theorem relies on the existence of the Einstein frame, since in the (Helmholtz--)Jordan frame the Dominant Energy Condition does not hold and the field variables are unrelated to the total energy of the system.Comment: 37 pp., TO-JLL-P 3/93 Dec 199

Initial Conditions for Inflation

Free scalar fields in de Sitter space have a one-parameter family of states invariant under the de Sitter group, including the standard thermal vacuum. We show that, except for the thermal vacuum, these states are unphysical when gravitational interactions are included. We apply these observations to the quantum state of the inflaton, and find that, at best, dramatic fine tuning is required for states other than the thermal vacuum to lead to observable features in the CMBR anisotropy.Comment: 31 pages, 4 figure

Spectrum of density fluctuations in Brans-Dicke chaotic inflation

In the context of Brans--Dicke theories, eternal inflation is described in such a way that the evolution of the inflaton field is determined by the value of the Planck mass in different regions of the universe. The Planck mass is given by the values of the Brans--Dicke field, which is coupled to the scalar curvature in the Lagrangian. We first calculate the joint probability distributions of the inflaton and Brans--Dicke fields, in order to compute the 3--volume ratios of homogeneous regions with arbitrary values of the fields still undergoing inflation with respect to thermalized regions. From these volume ratios one is able to extract information on the values of the fields measured by a typical observer for a given potential and, in particular, the typical value of the Planck mass at the end of inflation. In this paper, we investigate volume ratios using a regularization procedure suggested by Vilenkin, and the results are applied to powerlaw and double--well potentials. The spectrum of density fluctuations is calculated for generic potentials, and we discuss the likelihood of various scenarios that could tell us whether our region of the universe is typical or untypical depending on very general bounds on the evolution of the Brans--Dicke field.Comment: 26 pages, uuencoded compressed postscript file, two figures include

Psychosocial Outcomes in Orthognathic Surgery: A Review of the Literature

Objective: To identify and critically appraise the literature on the psychosocial outcomes of orthognathic surgery, reflect on the clinical and theoretical implications, and suggest avenues for future research. Design: A search of the literature was completed using the databases Web of Science, MEDLINE, and PsycINFO to identify English-language articles published since January 2001 that have reported a measure of psychosocial functioning posttreatment. Results: A total of 38 articles were eligible for inclusion in the review. The studies reported improvements in areas such as satisfaction with facial appearance, self-confidence, self-esteem, anxiety, and social functioning. Small percentages of patients were left dissatisfied or had difficulty adjusting to appearance change despite the absence of treatment complications. Gains in psychosocial functioning were maintained over several years, and satisfaction increased over time. Conclusions: There are consistent positive outcomes reported as a result of orthognathic surgery, but conclusions are limited by methodological issues in study design such as small sample sizes, limited use of control groups, and measures that fail to tap into relevant areas of psychosocial functioning. In addition, further exploration is required of processes such as adjustment to facial change and the role of psychological support during treatment