Acoustic Scattering from Mud Volcanoes and Carbonate Mounts

Submarine mud volcanoes occur in many parts of the world’s oceans and form an aperture for gas and fluidized mud emission from within the earth’s crust. Their characteristics are of considerable interest to the geology, geophysics, geochemistry, and underwater acoustics communities. For the latter, mud volcanoes are of interest in part because they pose a potential source of clutter for active sonar. Close-range (single-interaction) scattering measurements from a mud volcano in the Straits of Sicily show scattering10–15dB above the background. Three hypotheses were examined concerning the scattering mechanism: (1) gas entrained in sediment at/near mud volcano, (2) gas bubbles and/or particulates (emitted) in the water column, (3) the carbonate bio-construction covering the mud volcano edifice. The experimental evidence, including visual, acoustic, and nonacoustic sensors, rules out the second hypothesis (at least during the observation time) and suggests that, for this particular mud volcano the dominant mechanism is associated with carbonate chimneys on the mud volcano. In terms of scattering levels, target strengths of 4–14dB were observed from 800to3600Hz for a monostatic geometry with grazing angles of 3–5°. Similar target strengths were measured for vertically bistatic paths with incident and scattered grazing angles of 3–5° and 33–50°, respectively

Error analysis of Dobson spectrophotometer measurements of the total ozone content

A study of techniques for measuring atmospheric ozone is reported. This study represents the second phase of a program designed to improve techniques for the measurement of atmospheric ozone. This phase of the program studied the sensitivity of Dobson direct sun measurements and the ozone amounts inferred from those measurements to variation in the atmospheric temperature profile. The study used the plane - parallel Monte-Carlo model developed and tested under the initial phase of this program, and a series of standard model atmospheres

Quantum Kinetic Theory III: Simulation of the Quantum Boltzmann Master Equation

We present results of simulations of a em quantum Boltzmann master equation (QBME) describing the kinetics of a dilute Bose gas confined in a trapping potential in the regime of Bose condensation. The QBME is the simplest version of a quantum kinetic master equations derived in previous work. We consider two cases of trapping potentials: a 3D square well potential with periodic boundary conditions, and an isotropic harmonic oscillator. We discuss the stationary solutions and relaxation to equilibrium. In particular, we calculate particle distribution functions, fluctuations in the occupation numbers, the time between collisions, and the mean occupation numbers of the one-particle states in the regime of onset of Bose condensation.Comment: 12 pages, 15 figure

INTERREGIONAL EFFECTS OF REDUCED TIMBER HARVESTS: THE IMPACT OF THE NORTHERN SPOTTED OWL LISTING IN RURAL AND URBAN OREGON

A core-periphery, multiregional, input-output model of western Oregon is used to estimate impacts of periphery timber harvest reductions resulting from listing of an endangered species. Under the most probable scenario, 31,620 total jobs would be lost in the two regions. Fourteen percent of this impact is absorbed in the core (Metro) region. Forty percent of periphery and 80% of Metro jobs lost are from service sectors, a result of important core-periphery trade in central place services. Explicit inclusion of unemployment benefits for displaced workers reduces employment loss estimates by 12% to 14%.Resource /Energy Economics and Policy,

THE ROLE OF AGRICULTURE IN OREGON'S ECONOMIC BASE: FINDINGS FROM A SOCIAL ACCOUNTING MATRIX

Most studies of a state’'s economic base count as “"basic”" only the “"traditional"” exports of goods, federal spending, and business investment. “"Nontraditional”" elements of the economic base (including exports of services, federal transfers to state/local governments and households, and extraregional property income) are typically ignored. We construct a social accounting matrix (SAM) for Oregon and estimate Oregon’'s economic base accounting for both traditional and nontraditional elements. Almost 20% of Oregon’'s jobs depend on extraregional income to households (including government transfers and outside property income), 11% depend on lumber and wood and paper products, and 8% depend on agriculture.Agribusiness,

Unraveling quantum dissipation in the frequency domain

We present a quantum Monte Carlo method for solving the evolution of an open quantum system. In our approach, the density operator evolution is unraveled in the frequency domain. Significant advantages of this approach arise when the frequency of each dissipative event conveys information about the state of the system.Comment: 4 pages, 4 Postscript figures, uses RevTe

Magnetic Fields in Star-Forming Molecular Clouds I. The First Polarimetry of OMC-3 in Orion A

The first polarimetric images of the OMC-3 region of the Orion A filamentary molecular cloud are presented. Using the JCMT, we have detected polarized thermal emission at 850 microns from dust along a 6' length of the dense filament. The polarization pattern is highly ordered and is aligned with the filament throughout most of the region. The plane-of-sky magnetic field direction is perpendicular to the measured polarization. The mean percentage polarization is 4.2% with a 1 sigma dispersion of 1%. This region is part of the integral-shaped filament, and active star formation is ongoing along its length. The protostellar outflow directions do not appear to be consistently correlated with the direction of the plane-of-sky field or the filament structure itself. Depolarization toward the filament center, previously detected in many other star-forming cores and protostars, is also evident in our data. (abstract abridged)Comment: 9 pages plus 2 figures (1 colour); accepted for publication in the March 10, 2000 issue (vol. 531 #2) of The Astrophysical Journa

Kinetics of Bose-Einstein Condensation in a Trap

The formation process of a Bose-Einstein condensate in a trap is described using a master equation based on quantum kinetic theory, which can be well approximated by a description using only the condensate mode in interaction with a thermalized bath of noncondensate atoms. A rate equation of the form n = 2W(n)[(1-exp((mu_n - mu)/kT))n + 1] is derived, in which the difference between the condensate chemical potential mu_n and the bath chemical potential mu gives the essential behavior. Solutions of this equation, in conjunction with the theoretical description of the process of evaporative cooling, give a characteristic latency period for condensate formation and appear to be consistent with the observed behavior of both rubidium and sodium condensate formation.Comment: 9 pages, Revte