7,215 research outputs found
Correlation of chlorophyll, suspended matter, and related parameters of waters in the lower Chesapeake Bay area to LANDSAT-1 imagery
The author has identified the following significant results. An effort to relate water parameters of the lower Chesapeake Bay area to multispectral scanner images of LANDSAT 1 has shown that some spectral bands can be correlated to water parameters, and has demonstrated the feasibility of synoptic mapping of estuaries by satellite. Bands 5 and 6 were shown to be useful for monitoring total particles. Band 5 showed high correlation with suspended sediment concentration. Attenuation coefficients monitored continuously by ship along three baselines were cross correlated with radiance values on three days. Improved correlations resulted when tidal conditions were taken into consideration. A contouring program was developed to display sediment variation in the lower Chesapeake Bay from the MSS bands
Evolution of the bilayer nu = 1 quantum Hall state under charge imbalance
We use high-mobility bilayer hole systems with negligible tunneling to
examine how the bilayer nu = 1 quantum Hall state evolves as charge is
transferred from one layer to the other at constant total density. We map
bilayer nu = 1 state stability versus imbalance for five total densities
spanning the range from strongly interlayer coherent to incoherent. We observe
competition between single-layer correlations and interlayer coherence. Most
significantly, we find that bilayer systems that are incoherent at balance can
develop spontaneous interlayer coherence with imbalance, in agreement with
recent theoretical predictions.Comment: 4 pages, 4 figure
Correlation of ERTS multispectral imagery with suspended matter and chlorophyll in lower Chesapeake Bay
The feasibility of using multispectral satellite imagery to monitor the characteristics of estuarine waters is being investigated. Preliminary comparisons of MSS imagery with suspended matter concentrations, particle counts, chlorophyll, transmittance and bathymetry have been made. Some visual correlation of radiance with particulates and chlorophyll has been established. Effects of bathymetry are present, and their relation to transmittance and radiance is being investigated. Greatest detail in suspended matter is revealed by MSS band 5. Near-surface suspended sediment load and chlorophyll can be observed in bands 6 and 7. Images received to date have partially defined extent and location of high suspensate concentrations. Net quantity of suspended matter in the lower Bay has been decreasing since the inception of the study, and represents the diminution of turbid flood waters carried into the Bay in late September, 1972. The results so far point to the utility of MSS imagery in monitoring estuarine water character for the assessment of siltation, productivity, and water types
Global warming - some perspectives
Here the authors critically review the IPCC’s claim that global warming is “very likely” caused by human activity: such a
description underestimates the likelihood of the warming being due to this mechanism. Next examined are known alternative “natural”
mechanisms which could give rise to the warming if, despite many claims, the man-made explanation was false because of
compensation effects (greenhouse gases versus aerosol effects). Also, a number of difficulties, as yet unresolved, in the human-induced
warming explanation are considered
Programmed buckling by controlled lateral swelling in a thin elastic sheet
Recent experiments have imposed controlled swelling patterns on thin polymer
films, which subsequently buckle into three-dimensional shapes. We develop a
solution to the design problem suggested by such systems, namely, if and how
one can generate particular three-dimensional shapes from thin elastic sheets
by mere imposition of a two-dimensional pattern of locally isotropic growth.
Not every shape is possible. Several types of obstruction can arise, some of
which depend on the sheet thickness. We provide some examples using the
axisymmetric form of the problem, which is analytically tractable.Comment: 11 pages, 9 figure
A coherent triggered search for single spin compact binary coalescences in gravitational wave data
In this paper we present a method for conducting a coherent search for single
spin compact binary coalescences in gravitational wave data and compare this
search to the existing coincidence method for single spin searches. We propose
a method to characterize the regions of the parameter space where the single
spin search, both coincident and coherent, will increase detection efficiency
over the existing non-precessing search. We also show example results of the
coherent search on a stretch of data from LIGO's fourth science run but note
that a set of signal based vetoes will be needed before this search can be run
to try to make detections.Comment: 14 pages, 4 figure
Charge Imbalance and Bilayer 2D Electron Systems at
We use interlayer tunneling to study bilayer 2D electron systems at over a wide range of charge density imbalance, ,
between the two layers. We find that the strongly enhanced tunneling associated
with the coherent excitonic phase at small layer separation can
survive at least up to an imbalance of = 0.5, i.e
= (3/4, 1/4). Phase transitions between the excitonic state and
bilayer states which lack significant interlayer correlations can be induced in
three different ways: by increasing the effective interlayer spacing ,
the temperature , or the charge imbalance, . We observe that
close to the phase boundary the coherent phase can be absent at
= 0, present at intermediate , but then absent again
at large , thus indicating an intricate phase competition between
it and incoherent quasi-independent layer states. At zero imbalance, the
critical shifts linearly with temperature, while at = 1/3
the critical is only weakly dependent on . At = 1/3 we
report the first observation of a direct phase transition between the coherent
excitonic bilayer integer quantum Hall phase and the pair of single
layer fractional quantized Hall states at = 2/3 and .Comment: 13 pages, 8 postscript figures. Final published versio
Surface Geometry of C60 on Ag(111)
The geometry of adsorbed C60 influences its collective properties. We report the first dynamical low-energy electron diffraction study to determine the geometry of a C60 monolayer, Ag(111)-(23×23)30°-C60, and related density functional theory calculations. The stable monolayer has C60 molecules in vacancies that result from the displacement of surface atoms. C60 bonds with hexagons down, with their mirror planes parallel to that of the substrate. The results indicate that vacancy structures are the rule rather than the exception for C60 monolayers on close-packed metal surfaces. © 2009 The American Physical Society
Telecommunications systems design techniques handbook
Handbook presents design and analysis of tracking, telemetry, and command functions utilized in these systems with particular emphasis on deep-space telecommunications. Antenna requirements are also discussed. Handbook provides number of tables outlining various performance criteria. Block diagrams and performance charts are also presented
Spin Susceptibility and Gap Structure of the Fractional-Statistics Gas
This paper establishes and tests procedures which can determine the electron
energy gap of the high-temperature superconductors using the model
with spinon and holon quasiparticles obeying fractional statistics. A simpler
problem with similar physics, the spin susceptibility spectrum of the spin 1/2
fractional-statistics gas, is studied. Interactions with the density
oscillations of the system substantially decrease the spin gap to a value of
, much less than the mean-field value of
. The lower few Landau levels remain visible, though broadened
and shifted, in the spin susceptibility. As a check of the methods, the
single-particle Green's function of the non-interacting Bose gas viewed in the
fermionic representation, as computed by the same approximation scheme, agrees
well with the exact results. The same mechanism would reduce the gap of the
model without eliminating it.Comment: 35 pages, written in REVTeX, 16 figures available upon request from
[email protected]
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