The airborne lava-seawater interaction plume at Kilauea Volcano, Hawaii

Petrology igneous metamorphic and volcanic studies; medm0

Consistent modeling of the geodetic precession in Earth rotation

A highly precise model for the motion of a rigid Earth is indispensable to reveal the effects of non-rigidity in the rotation of the Earth from observations. To meet the accuracy goal of modern theories of Earth rotation of 1 microarcsecond (muas) it is clear, that for such a model also relativistic effects have to be taken into account. The largest of these effects is the so called geodetic precession. In this paper we will describe this effect and the standard procedure to deal with it in modeling Earth rotation up to now. With our relativistic model of Earth rotation Klioner et al. (2001) we are able to give a consistent post-Newtonian treatment of the rotational motion of a rigid Earth in the framework of General Relativity. Using this model we show that the currently applied standard treatment of geodetic precession is not correct. The inconsistency of the standard treatment leads to errors in all modern theories of Earth rotation with a magnitude of up to 200 muas for a time span of one century.Comment: 6 pages, 4 figures, 1 table, published in the Proceedings of the VII Hotine-Marussi Symposium, Chapter 4

A new method of alpha ray measurement using a Quadrupole Mass Spectrometer

We propose a new method of alpha($\alpha$)-ray measurement that detects helium atoms with a Quadrupole Mass Spectrometer(QMS). A demonstration is undertaken with a plastic-covered $^{241}$Am $\alpha$-emitting source to detect $\alpha$-rays stopped in the capsule. We successfully detect helium atoms that diffuse out of the capsule by accumulating them for one to 20 hours in a closed chamber. The detected amount is found to be proportional to the accumulation time. Our method is applicable to probe $\alpha$-emitting radioactivity in bulk material.Comment: 8 pages, 6 figure

A Fourier transform spectrometer for visible and near ultra-violet measurements of atmospheric absorption

The development of a prototype, ground-based, Sun-pointed Michelson interferometric spectrometer is described. Its intended use is to measure the atmospheric amount of various gases which absorb in the near-infrared, visible, and near-ultraviolet portions of the electromagnetic spectrum. Preliminary spectra which contain the alpha, 0.8 micrometer, and rho sigma tau water vapor absorption bands in the near-infrared are presented to indicate the present capability of the system. Ultimately, the spectrometer can be used to explore the feasible applications of Fourier transform spectroscopy in the ultraviolet where grating spectrometers were used exclusively

Bubble wall perturbations coupled with gravitational waves

We study a coupled system of gravitational waves and a domain wall which is the boundary of a vacuum bubble in de Sitter spacetime. To treat the system, we use the metric junction formalism of Israel. We show that the dynamical degree of the bubble wall is lost and the bubble wall can oscillate only while the gravitational waves go across it. It means that the gravitational backreaction on the motion of the bubble wall can not be ignored.Comment: 23 pages with 3 eps figure

Quantum Mechanical Carrier of the Imprints of Gravitation

We exhibit a purely quantum mechanical carrier of the imprints of gravitation by identifying for a relativistic system a property which (i) is independent of its mass and (ii) expresses the Poincare invariance of spacetime in the absence of gravitation. This carrier consists of the phase and amplitude correlations of waves in oppositely accelerating frames. These correlations are expressed as a Klein-Gordon-equation-determined vector field whose components are the ``Planckian power'' and the ``r.m.s. thermal fluctuation'' spectra. The imprints themselves are deviations away from this vector field.Comment: 8 pages, RevTex. Html version of this and related papers on accelerated frames available at http://www.math.ohio-state.edu/~gerlac

On the exciton binding energy in a quantum well

We consider a model describing the one-dimensional confinement of an exciton in a symmetrical, rectangular quantum-well structure and derive upper and lower bounds for the binding energy $E_b$ of the exciton. Based on these bounds, we study the dependence of $E_b$ on the width of the confining potential with a higher accuracy than previous reports. For an infinitely deep potential the binding energy varies as expected from $1 Ry$ at large widths to $4 Ry$ at small widths. For a finite potential, but without consideration of a mass mismatch or a dielectric mismatch, we substantiate earlier results that the binding energy approaches the value $1 Ry$ for both small and large widths, having a characteristic peak for some intermediate size of the slab. Taking the mismatch into account, this result will in general no longer be true. For the specific case of a $Ga_{1-x}Al_{x}As/GaAs/Ga_{1-x}Al_{x}As$ quantum-well structure, however, and in contrast to previous findings, the peak structure is shown to survive.Comment: 32 pages, ReVTeX, including 9 figure