1,832 research outputs found
Using controlled source em methods to constrain physical properties of the uppermost seafloor: an example of instrumentation and a case study from a gas pock-mark offshore ireland
Determination of step--edge barriers to interlayer transport from surface morphology during the initial stages of homoepitaxial growth
We use analytic formulae obtained from a simple model of crystal growth by
molecular--beam epitaxy to determine step--edge barriers to interlayer
transport. The method is based on information about the surface morphology at
the onset of nucleation on top of first--layer islands in the submonolayer
coverage regime of homoepitaxial growth. The formulae are tested using kinetic
Monte Carlo simulations of a solid--on--solid model and applied to estimate
step--edge barriers from scanning--tunneling microscopy data on initial stages
of Fe(001), Pt(111), and Ag(111) homoepitaxy.Comment: 4 pages, a Postscript file, uuencoded and compressed. Physical Review
B, Rapid Communications, in press
A simple proof of Hardy-Lieb-Thirring inequalities
We give a short and unified proof of Hardy-Lieb-Thirring inequalities for
moments of eigenvalues of fractional Schroedinger operators. The proof covers
the optimal parameter range. It is based on a recent inequality by Solovej,
Soerensen, and Spitzer. Moreover, we prove that any non-magnetic Lieb-Thirring
inequality implies a magnetic Lieb-Thirring inequality (with possibly a larger
constant).Comment: 12 page
Real time thermal propagtors for massive gauge bosons
We derive Feynman rules for gauge theories exhibiting spontaneous symmetry
breaking using the real-time formalism of finite temperature field theory. We
also derive the thermal propagators where only the physical degrees of freedom
are given thermal boundary conditions. We analyse the abelian Higgs model and
find that these new propagators simplify the calculation of the thermal
contribution to the self energy.Comment: 7 pages, late
Withdrawal of water by industry in Illinois, 1970-1971
Includes bibliographical references (p. 17)
Recommended from our members
Permeability reduction by pyrobitumen, mineralization, and stress along large natural fractures in sandstones at 18,300 ft. depth: Destruction of a reservoir
Production of gas from the Frontier Formation at 18,300 R depth in the Frewen No. 4 Deep well, eastern Green River basin (Wyoming), was uneconomic despite the presence of numerous open natural fractures. Initial production tested at 500 MCFD, but dropped from 360 MCFD to 140 MCFD during a 10-day production test, and the well was abandoned. Examination of the fractures in the core suggests several probable reasons for this poor production. One factor is the presence of a hydrocarbon residue (carbon) which filled much of the porosity left in the smaller fractures after mineralization. An equally important factor is probably the reorientation of the in situ horizontal compressive stress to a trend normal to the main fractures, and which now acts to close fracture apertures rapidly during reservoir drawdown. This data set has unpleasant implications for the search for similar, deep fractured reservoirs
Proposed stratotype for the base of the Lawsonian Stage (Cambrian Stage 10) at the First Appearance Datum of Eoconodontus notchpeakensis (Miller) in the House Range, Utah, USA
Identity of the imaginary-time and real-time thermal propagators for scalar bound states in a one-generation Nambu-Jona-Lasinio model
By rigorous reanalysis of the results, we have proven that the propagators at
finite temperature for scalar bound states in one-generation fermion condensate
scheme of electroweak symmetry breaking are in fact identical in the
imaginary-time and the real-time formalism. This dismisses the doubt about
possible discrepancy between the two formalisms in this problem. Identity of
the derived thermal transformation matrices of the real-time matrix propagators
for scalar bound states without and with chemical potential and the ones for
corresponding elementary scalar particles shows similarity of thermodynamic
property between the two types of particles. Only one former inference is
modified, i.e. when the two flavors of fermions have unequal nonzero masses,
the amplitude of the composite Higgs particle will decay instead grow in time.Comment: 5 pages, revtex4, no figure
Ginzburg-Landau vortex dynamics with pinning and strong applied currents
We study a mixed heat and Schr\"odinger Ginzburg-Landau evolution equation on
a bounded two-dimensional domain with an electric current applied on the
boundary and a pinning potential term. This is meant to model a superconductor
subjected to an applied electric current and electromagnetic field and
containing impurities. Such a current is expected to set the vortices in
motion, while the pinning term drives them toward minima of the pinning
potential and "pins" them there. We derive the limiting dynamics of a finite
number of vortices in the limit of a large Ginzburg-Landau parameter, or \ep
\to 0, when the intensity of the electric current and applied magnetic field
on the boundary scale like \lep. We show that the limiting velocity of the
vortices is the sum of a Lorentz force, due to the current, and a pinning
force. We state an analogous result for a model Ginzburg-Landau equation
without magnetic field but with forcing terms. Our proof provides a unified
approach to various proofs of dynamics of Ginzburg-Landau vortices.Comment: 48 pages; v2: minor errors and typos correcte
Algae in Selected Illinois Streams, 1971-1976
During the 5-year period, October 1971 through September 1976, samples of water from 21 Illinois streams at 26 locations were collected monthly and examined to determine the concentration and genera of algae. Data have been evaluated for algal composition, density, diversity indices, and seasonal succession for each stream location. At most sampling locations, algal densities ranged from 500 to 2000 cts/ml. The 5-year geometric means extended from 880 to 1500 cts/ml. From 24 to 30 different algal genera were recovered from each station and, in all, 56 genera were detected. The average diversity index for each station ranged from 1.11 to 1.36 bits per individual. The highest density of 60,000 cts/ml occurred on July 11, 1975, in the Fox River at Algonquin. The diatoms Navicula and Cyclotella were the most frequently observed algae. In addition to these, the green algae Scenedesmus and Crucigenia and the diatom Melosira were often dominant. From sample to sample, season to season, and year to year, the genera found at any sampling station varied considerably. Generally, the annual maximum population occurred in the spring. However, the experience gained from this study supports the conclusion that it is impossible to predict algal density, composition, or succession in the flowing streams of Illinois.publishedpeer reviewedOpe
- …