Direct Detection of Gravity Waves through High-Precision Astrometry

It is generally accepted that a first ever direct detection of gravity waves would herald a new era in astronomy and in fundamental physics. Ever since the early sixties, increasingly larger human and material resources are being invested in the detection effort. Unfortunately, the gravity wave effects one has had to exploit so far are extraordinarily small and are usually very many orders of magnitude smaller than the noise involved. The detectors that are presently at the most advanced stage of development hope to register extremely rare, instantaneous longitudinal shifts that are expected to be orders of magnitude smaller than one Fermi. However, it was recently shown that gravity waves can manifest themselves through much larger effects than previously envisaged. One of these new effects is the periodic, apparent shift in a star's angular position due to a foreground gravity wave source. The comparative largeness of this effect stems from its being proportional not to the inverse of the gravity wave source's distance to the Earth, but to the inverse of its distance to the star's line of sight. In certain optimal but not unrealistic cases, the amplitude of this effect can reach the critical bar of one micro-arcsecond, thus raising the prospect that the long awaited first direct detection of gravity waves could be achieved by a high precision astrometry space mission such as GAIA.Comment: 11 pages, latex, no figure

Gravity-Wave Watching

It is suggested that gravity waves could, in several cases, be detected by means of already (or shortly to be) available technology, independently of current efforts of detection. The present is a follow-up on a recently suggested detection strategy based on gravity-wave-induced deviations of null geodesics. The new development is that a way was found to probe the waves close to the source, where they are several orders of magnitude larger than on the Earth. The effect translates into apparent shifts in stellar angular positions that could be as high as $10^{-7}$ arcsec, which is just about the present theoretical limit of detectability. (Calculation improved; results unchanged.)Comment: 17pp, plain LaTeX, UBCTP-93-00

Induced-gravity Inflation and the Density Perturbation Spectrum

Recent experimental determinations of the spectral index describing the scalar mode spectrum of density perturbations encourage comparison with predictions from models of the very early universe. Unlike extended inflation, Induced-gravity Inflation predicts a power spectrum with $0.98 \leq n_s \leq 1.00$, in close agreement with the experimental measurements.Comment: 11pp, no figures. Plain LaTeX. HUTP-94/A011. Revised edition -- Forthcoming in Physics Letters

A comparative immunohistochemical study of Ki-67 expression in adenomatoid odontogenic tumour, unicystic ameloblastoma and dentigerous cyst

Magister Chirurgiae Dentium - MChDThe aim of this study was to investigate the biological profile oftheAOT by comparing the Ki-67 proliferative indices of the AOT, Unicystic Ameloblastoma (UA) and Dentigerous Cyst (DC) using ImmunoRatio® software. Adenomatoid Odontogenic Tumours (AOTs) are classified as benign epithelial odontogenic neoplasms with mature fibrous stroma, without odontogenic mesenchyme. However these lesions, like odontomes, occur almost exclusively during the final period of odontogenesis, and clinically behave like self-limiting hamartomatous lesions. Histologically they seem to arise from the lining of dental follicle

Determination of heat transfer coefficient for hot stamping process

© 2015 The Authors.The selection of the heat transfer coefficient is one of the most important factors that determine the reliability of FE simulation results of a hot stamping process, in which the formed component is held within cold dies until fully quenched. The quenching process could take up to 10. seconds. In order to maximise the production rate, the optimised quenching parameters should be identified to achieve the highest possible quenching rate and to reduce the quenching time. For this purpose, a novel-testing rig for the Gleeble 3800 thermo- mechanical simulator was designed and manufactured, with an advanced control system for temperature and contact pressure. The effect of contact pressure on the heat transfer coefficient was studied. The findings of this research will provide useful guidelines for the selection of the heat transfer coefficient in simulations of hot stamping processes and useful information for the design of hot stamping processes

Application Of The Differential Quadrature Method To Problems In Engineering Mechanics

The numerical solution of linear and nonlinear partial differential equations plays a prominent role in many areas of engineering and physical sciences. In many cases all that is desired is a moderately accurate solution at a few grid points that can be calculated rapidly. The standard finite difference method currently in use have the characteristic that the solution must be calculated with a large number of mesh points in order to obtain moderately accurate results at the points of interest. Consequently, both the computing time and storage required often prohibit the calculation. Furthermore, the mathematical techniques involved in the finite difference schemes or in the Fourier transform methods, are often quite sophisticated and thus not easily learned or used.The differential quadrature method (DQM) is a numerical solution technique, which has been presented in this thesis. This method is a simple and direct technique, which can be applied in a large number of cases to circumvent the difficulties of programming complex algorithms for the computer, as well as excessive use of storage and computer time. The initial and/or boundary value problems can be solved by this method directly and efficiently. The accuracy of the differential quadrature (DQ) method depends mainly on the accuracy of the weighting coefficient computation, which is a vital key of the method. In this thesis, the technique has been illustrated with the solution of six partial differential equations arising in Heat transfer, Poisson and Torsion problem with accurate weighting coefficient computation and two types of mesh· points distribution (equally spaced and unequally spaced). In all cases, the obtained DQ numerical results are of good accuracy with the exact solutions and hence show the potentiality of the method. It is also shown that the obtained DQ results in this thesis either agree very well or improved than those of some similar published results. This method is a vital alternative to the conventional numerical methods, such as finite difference and finite element methods. It is expected that this technique can be applied in a large number of cases in science and engineering to circumvent both the above-mentioned conventional difficulties

Generalized slow-roll inflation

The slow-roll approximation to inflation is ultimately justified by the presence of inflationary attractors for the orbits of the solutions of the dynamical equations in phase space. There are many indications that the inflaton field couples nonminimally to the spacetime curvature: the existence of attractor points for inflation with nonminimal coupling is demonstrated, subject to a condition on the inflaton potential and the value of the coupling constant.Comment: 14 pages, LaTeX, some typos correcte