3,863 research outputs found
Ill-posedness of degenerate dispersive equations
In this article we provide numerical and analytical evidence that some
degenerate dispersive partial differential equations are ill-posed.
Specifically we study the K(2,2) equation and
the "degenerate Airy" equation . For K(2,2) our results are
computational in nature: we conduct a series of numerical simulations which
demonstrate that data which is very small in can be of unit size at a
fixed time which is independent of the data's size. For the degenerate Airy
equation, our results are fully rigorous: we prove the existence of a compactly
supported self-similar solution which, when combined with certain scaling
invariances, implies ill-posedness (also in )
On Unitarity Based Relations Between Various Lepton Family Violating Processes
Simple "unitarity inspired" relations between two- and three-body lepton
flavor violating decays are noted and discussed. In the absence of
cancellations, the existing strong bounds on and severly constrain two-body lepton flavor violating decays.Comment: 5 pages, 3 figure
Pollen dimorphism and dioecy in Vitis aestivalis
Problems of low production and sterile pollen in varieties of Vitis vinifera may be tracable to their ancestral relations with dioecious wild grapes.Like V. riparia, the wild summer grape V. aestivalis has dimorphic male and female flowers; but unlike V. riparia it also has dimorphic pollen grains with the pollen from the female flower being significantly smaller.It seems fairly certain that V. aestivalis is truly dioecious
Monte Carlo simulations of ordering in ferromagnetic-antiferromagnetic bilayers
Monte Carlo simulations have been used to study phase transitions on coupled
anisotropic ferro/antiferromagnetic (FM/AFM) films of classical Heisenberg
spins. We consider films of different thicknesses, with fully compensated
exchange across the FM/AFM interface. We find indications of a phase transition
on each film, occuring at different temperatures. It appears that both
transition temperatures depend on the film thickness.Comment: Revtex, 4 pages, 4 figure
Recommended from our members
Coordination of Geological and Engineering Research in Support of the Gulf Coast Co-Production Program - Final Report
At Northeast Hitchcock field, the presence of the Skolithos assemblage and other structures has supported the interpretation of shallow-marine, tidal, distributary-mouth-bar, and channel depositional environments for most of the major reservoir sandstones. Several shaly horizons exhibit characteristics of interdistributary bays, and the Frio A is capped by a thin sequence of crevasse splays and washover sands that represent the initiation of the transgression that overlapped the Frio in Anahuac times.
The high-energy depositional environment of reworked distributary-mouth-bar sandstones is the major control of the high porosity (around 30 percent) and permeability (around 1,000 millidarcies) in Frio A sandstones at Northeast Hitchcock field. Well-winnowed sandstones with high porosities and permeabilities contain abundant authigenic kaolinite and have served as preferential conduits for migrating acid waters and major fluid flow during co-production. Authigenic clay can create fluid production problems due to its delicate structure. Dislodged clay may obstruct pore throats at high production rates, necessitating the determination of a maximum safe rate of fluid production for co-produced wells.
Middle and lower Miocene barrier island sands, buried at depths from 3,500 to 6,800 feet in Northeast Hitchcock field, have the potential to receive large volumes of co-produced brines from the Frio 1-A reservoir. These sands exhibit high permeabilities exceeding 2,000 millidarcies, are internally homogeneous, and are laterally extensive in the field area. The 6,150-foot sand (lower Miocene) was chosen for initial brine disposal in the H.D.S. Thompson No. 3 brine-disposal well based on these criteria. The 3,780-foot sand (middle Miocene) is recommended for future up-hole brine disposal in the H.D.S. Thompson No. 3 well because it is shallower, requiring less injection pressure and lower costs for brine disposal.Bureau of Economic Geolog
Recommended from our members
Coordination of Geological and Engineering Research in Support of the Gulf Coast Co-Production Program
Shallow-marine sandstones in Northeast Hitchcock field having high porosities and
permeabilities contain abundant authigenic kaolinite and have acted as preferential conduits
for fluid migration. Authigenic clay creates fluid production problems because of
its delicate structure. Dislodged clay will obstruct pore throats at high production
rates. A maximum safe rate of fluid production will need to be determined for co-produced
wells.
Middle and lower Miocene barrier-island sands in Northeast Hitchcock field have the
potential for receiving large volumes of co-produced brines. These sands have permeabilities
in excess of 2,000 md, are internally homogeneous, and are laterally extensive in
the field area.
Detailed geologic analyses of two reservoirs in Seeligson field delineate heterogeneous, fluvial sandstones that probably contain isolated, undrained reservoir compartments.
Zone 15 can be subdivided into at least four genetic sandstones, and Zone 18-C can
be subdivided into two separate sandstones.
Two new pool discoveries (Miocene) in Tom O'Connor field developed during growth-fault
activity along the Vicksburg Fault Zone. Deposition of these sandstones, as part of an
offshore system during initial parasequence deposition, was confined between the Vicksburg
Fault Zone and the Tom O'Connor anticlinal crest.Bureau of Economic Geolog
Response of selected plant and insect species to simulated solid rocket exhaust mixtures and to exhaust components from solid rocket fuels
The effects of solid rocket fuel (SRF) exhaust on selected plant and and insect species in the Merritt Island, Florida area was investigated in order to determine if the exhaust clouds generated by shuttle launches would adversely affect the native, plants of the Merritt Island Wildlife Refuge, the citrus production, or the beekeeping industry of the island. Conditions were simulated in greenhouse exposure chambers and field chambers constructed to model the ideal continuous stirred tank reactor. A plant exposure system was developed for dispensing and monitoring the two major chemicals in SRF exhaust, HCl and Al203, and for dispensing and monitoring SRF exhaust (controlled fuel burns). Plants native to Merritt Island, Florida were grown and used as test species. Dose-response relationships were determined for short term exposure of selected plant species to HCl, Al203, and mixtures of the two to SRF exhaust
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