An Overview of Gravitational-Wave Sources

We review current best estimates of the strength and detectability of the gravitational waves from a variety of sources, for both ground-based and space-based detectors, and we describe the information carried by the waves

Locating the magnetospheric ring current

Protons are studied in the global depression of the earth's horizontal magnetic field. It is shown that 10 to 100 keV protons dominate ring current energetics in two preferred regions of cyclotron instability, which serve as stable trapping boundaries for ring current protons. The only apparent means of removing this stably trapped belt of particles are considered to be by charge exchange interactions, or by outward expansion of the plasmapause to erode the ring current. Both of these processes require about two days, which is the characteristic decay period of the main phase depression. Questions whose answers are necessary to formulate a quantitative theory of geomagnetic storms which relates main phase depression to solar wind parameters are included

Unstable growth of unducted whistlers propagating at an angle to the geomagnetic field

Unstable growth rate of unducted whistler waves propagating at angle to geomagnetic fiel

The Role of Risk in the Decision to Produce Post-Decoupling - A Stochastic Budgeting Example

Under the Mac Sharry and Agenda 2000 reforms, direct payments comprised a significant portion of farmers' income in the EU. Farmers had to engage in production to receive these payments but the payments were relatively risk-free and therefore risk may not have played an important role in the production decision. This paper considers the effect of the decoupling of direct payments from production in the EU and in particular, on the role of production risk in the decision making process. In an environment where direct payments are completely decoupled from production, farmers may engage in an 'entitlement farming' system, that is retain their land only to activate the decoupled payment and not actually produce any tangible goods. This paper examines the effect of production risk on the economic trade off between 'entitlement farming' and conventional farming. A stochastic budgeting model is developed for two representative farms. The model is used to measure the probability that the returns to the 'entitlement farming' system could be higher than the profit emanating from a conventional farming system given production risk. The results show that for the less efficient representative farm, the probability of achieving a significantly higher profit by engaging in entitlement farming is 46 percent, while further analysis shows that there is a 9 percent probability that profits from conventional farming systems would be only marginally higher than the 'entitlement farming' option.Decoupling, Risk Analysis, Production Risk, Decision Analysis, Stochastic Modelling, Agricultural and Food Policy, Risk and Uncertainty, Q12, Q18,

Parton Distributions

I discuss our current understanding of parton distributions. I begin with the underlying theoretical framework, and the way in which different data sets constrain different partons, highlighting recent developments. The methods of examining the uncertainties on the distributions and those physical quantities dependent on them is analysed. Finally I look at the evidence that additional theoretical corrections beyond NLO perturbative QCD may be necessary, what type of corrections are indicated and the impact these may have on the uncertainties.Comment: Invited talk at "XXI International Symposium on Lepton and Photon Interactions at High Energies," (Fermilab, Chicago, August 2003). 12 pages, 21 figure

Uncertainty in Measurements of Distance

Ng and van Dam have argued that quantum theory and general relativity give a lower bound of L^{1/3} L_P^{2/3} on the uncertainty of any distance, where L is the distance to be measured and L_P is the Planck length. Their idea is roughly that to minimize the position uncertainty of a freely falling measuring device one must increase its mass, but if its mass becomes too large it will collapse to form a black hole. Here we show that one can go below the Ng-van Dam bound by attaching the measuring device to a massive elastic rod. Relativistic limitations on the rod's rigidity, together with the constraint that its length exceeds its Schwarzschild radius, imply that zero-point fluctuations of the rod give an uncertainty greater than or equal to L_P.Comment: 5 pages LaTe

The geometry of a naked singularity created by standing waves near a Schwarzschild horizon, and its application to the binary black hole problem

The most promising way to compute the gravitational waves emitted by binary black holes (BBHs) in their last dozen orbits, where post-Newtonian techniques fail, is a quasistationary approximation introduced by Detweiler and being pursued by Price and others. In this approximation the outgoing gravitational waves at infinity and downgoing gravitational waves at the holes' horizons are replaced by standing waves so as to guarantee that the spacetime has a helical Killing vector field. Because the horizon generators will not, in general, be tidally locked to the holes' orbital motion, the standing waves will destroy the horizons, converting the black holes into naked singularities that resemble black holes down to near the horizon radius. This paper uses a spherically symmetric, scalar-field model problem to explore in detail the following BBH issues: (i) The destruction of a horizon by the standing waves. (ii) The accuracy with which the resulting naked singularity resembles a black hole. (iii) The conversion of the standing-wave spacetime (with a destroyed horizon) into a spacetime with downgoing waves by the addition of a ``radiation-reaction field''. (iv) The accuracy with which the resulting downgoing waves agree with the downgoing waves of a true black-hole spacetime (with horizon). The model problem used to study these issues consists of a Schwarzschild black hole endowed with spherical standing waves of a scalar field. It is found that the spacetime metric of the singular, standing-wave spacetime, and its radiation-reaction-field-constructed downgoing waves are quite close to those for a Schwarzschild black hole with downgoing waves -- sufficiently close to make the BBH quasistationary approximation look promising for non-tidally-locked black holes.Comment: 12 pages, 6 figure

The Ioway in Missouri

Review of: "The Ioway in Missouri," by Greg Olson

Alien Registration- Thorne, Alberta C. (Houlton, Aroostook County)

https://digitalmaine.com/alien_docs/34893/thumbnail.jp