8,342 research outputs found
Adjusting the tasseled cap brightness and greenness factors for atmospheric path radiance and absorption on a pixel by pixel basis
A radiative transfer model was used to convert ground measured reflectances into the radiance at the top of the atmosphere, for several levels of atmospheric path radiance. The radiance in MSS7 (0.8 to 1.1 m) was multiplied by the transmission fraction for atmospheres having different levels of precipitable water. The radiance values were converted to simulated LANDSAT digital counts for four path radiance levels and four levels of precipitable water. These values were used to calculate the Kauth-Thomas brightness, greenness, yellowness, and nonsuch factors. Brightness was affected by surface conditions and path radiance. Greenness was affected by surface conditions, path radiance, and precipitable water. Yellowness was affected by path radiance and nonsuch by precipitable water, and both factors changed only slightly with surface conditions. Yellowness and nonsuch were used to adjust brightness and greenness to produce factors that were affected only by surface conditions such as soils and vegetation, and not by path radiance and precipitable water
A priori probability that a qubit-qutrit pair is separable
We extend to arbitrarily coupled pairs of qubits (two-state quantum systems)
and qutrits (three-state quantum systems) our earlier study (quant-ph/0207181),
which was concerned with the simplest instance of entangled quantum systems,
pairs of qubits. As in that analysis -- again on the basis of numerical
(quasi-Monte Carlo) integration results, but now in a still higher-dimensional
space (35-d vs. 15-d) -- we examine a conjecture that the Bures/SD (statistical
distinguishability) probability that arbitrarily paired qubits and qutrits are
separable (unentangled) has a simple exact value, u/(v Pi^3)= >.00124706, where
u = 2^20 3^3 5 7 and v = 19 23 29 31 37 41 43 (the product of consecutive
primes). This is considerably less than the conjectured value of the Bures/SD
probability, 8/(11 Pi^2) = 0736881, in the qubit-qubit case. Both of these
conjectures, in turn, rely upon ones to the effect that the SD volumes of
separable states assume certain remarkable forms, involving "primorial"
numbers. We also estimate the SD area of the boundary of separable qubit-qutrit
states, and provide preliminary calculations of the Bures/SD probability of
separability in the general qubit-qubit-qubit and qutrit-qutrit cases.Comment: 9 pages, 3 figures, 2 tables, LaTeX, we utilize recent exact
computations of Sommers and Zyczkowski (quant-ph/0304041) of "the Bures
volume of mixed quantum states" to refine our conjecture
Author Correction: Embodiment in a Child-Like Talking Virtual Body Influences Object Size Perception, Self-Identification, and Subsequent Real Speaking
Correction to: Scientific Reports https://doi.org/10.1038/s41598-017-09497-3, published online 29 August 201
Coupled modelling of subglacial hydrology and calving-front melting at Store Glacier, West Greenland
Abstract. We investigate the subglacial hydrology of Store Glacier in West Greenland,
using the open-source, full-Stokes model Elmer/Ice in a novel 3D application
that includes a distributed water sheet, as well as discrete channelised
drainage, and a 1D model to simulate submarine plumes at the calving front.
At first, we produce a baseline winter scenario with no surface meltwater.
We then investigate the hydrological system during summer, focussing
specifically on 2012 and 2017, which provide examples of high and low
surface-meltwater inputs, respectively. We show that the common assumption
of zero winter freshwater flux is invalid, and we find channels over 1 m2
in area occurring up to 5 km inland in winter. We also find that the production of
water from friction and geothermal heat is sufficiently high to drive
year-round plume activity, with ice-front melting averaging 0.15 m d−1.
When the model is forced with seasonally averaged surface melt from summer,
we show a hydrological system with significant distributed sheet activity
extending 65 and 45 km inland in 2012 and 2017, respectively; while
channels with a cross-sectional area higher than 1 m2 form as far as 55 and 30 km inland. Using daily values for the surface melt as forcing, we
find only a weak relationship between the input of surface meltwater and the
intensity of plume melting at the calving front, whereas there is a strong
correlation between surface-meltwater peaks and basal water pressures. The
former shows that storage of water on multiple timescales within the
subglacial drainage system plays an important role in modulating subglacial
discharge. The latter shows that high melt inputs can drive high basal water
pressures even when the channelised network grows larger. This has
implications for the future velocity and mass loss of Store Glacier, and the
consequent sea-level rise, in a warming world.
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Testing Spatial Noncommutativity via Magnetic Hyperfine Structure Induced by Fractional Angular Momentum of Rydberg System
An approach to solve the critical problem of testing quantum effects of
spatial noncommutativity is proposed. Magnetic hyperfine structures in a
Rydberg system induced by fractional angular momentum originated from spatial
noncommutativity are discussed. The orders of the corresponding magnetic
hyperfine splitting of spectrum lie within the
limits of accuracy of current experimental measurements. Experimental tests of
physics beyond the standard model are the focus of broad interest. We note that
the present approach is reasonable achievable with current technology. The
proof is based on very general arguments involving only the deformed
Heisenberg-Weyl algebra and the fundamental property of angular momentum. Its
experimental verification would constitute an advance in understanding of
fundamental significance, and would be a key step towards a decisive test of
spatial noncommutativity.Comment: 11 pages, no figure
Realistic Tight Binding Model for the Electronic Structure of II-VI Semiconductors
We analyze the electronic structure of group II-VI semiconductors obtained
within LMTO approach in order to arrive at a realistic and minimal tight
binding model, parameterized to provide an accurate description of both valence
and conduction bands. It is shown that a nearest-neighbor model is
fairly sufficient to describe to a large extent the electronic structure of
these systems over a wide energy range, obviating the use of any fictitious
orbital. The obtained hopping parameters obey the universal scaling law
proposed by Harrison, ensuring transferability to other systems. Furthermore,
we show that certain subtle features in the bonding of these compounds require
the inclusion of anion-anion interactions in addition to the nearest-neighbor
cation-anion interactions.Comment: 9 pages, 9 figure
Molecular Gas, Dust and Star Formation in Galaxies: II. Dust properties and scalings in \sim\ 1600 nearby galaxies
We aim to characterize the relationship between dust properties. We also aim
to provide equations to estimate accurate dust properties from limited
observational datasets.
We assemble a sample of 1,630 nearby (z<0.1) galaxies-over a large range of
Mstar, SFR - with multi-wavelength observations available from wise, iras,
planck and/or SCUBA. The characterization of dust emission comes from SED
fitting using Draine & Li dust models, which we parametrize using two
components (warm and cold ). The subsample of these galaxies with global
measurements of CO and/or HI are used to explore the molecular and/or atomic
gas content of the galaxies.
The total Lir, Mdust and dust temperature of the cold component (Tc) form a
plane that we refer to as the dust plane. A galaxy's sSFR drives its position
on the dust plane: starburst galaxies show higher Lir, Mdust and Tc compared to
Main Sequence and passive galaxies. Starburst galaxies also show higher
specific Mdust (Mdust/Mstar) and specific Mgas (Mgas/Mstar). The Mdust is more
closely correlated with the total Mgas (atomic plus molecular) than with the
individual components. Our multi wavelength data allows us to define several
equations to estimate Lir, Mdust and Tc from one or two monochromatic
luminosities in the infrared and/or sub-millimeter.
We estimate the dust mass and infrared luminosity from a single monochromatic
luminosity within the R-J tail of the dust emission, with errors of 0.12 and
0.20dex, respectively. These errors are reduced to 0.05 and 0.10 dex,
respectively, if the Tc is used. The Mdust is correlated with the total Mism
(Mism \propto Mdust^0.7). For galaxies with Mstar 8.5<log(Mstar/Msun) < 11.9,
the conversion factor \alpha_850mum shows a large scatter (rms=0.29dex). The SF
mode of a galaxy shows a correlation with both the Mgass and Mdust: high
Mdust/Mstar galaxies are gas-rich and show the highest SFRs.Comment: 24 pages, 28 figures, 6 tables, Accepted for publication in A&
From presence to consciousness through virtual reality
Immersive virtual environments can break the deep, everyday connection between where our senses tell us we are and where we are actually located and whom we are with. The concept of 'presence' refers to the phenomenon of behaving and feeling as if we are in the virtual world created by computer displays. In this article, we argue that presence is worthy of study by neuroscientists, and that it might aid the study of perception and consciousness
Bioprocess modelling of biohydrogen production by Rhodopseudomonas palustris: Model development and effects of operating conditions on hydrogen yield and glycerol conversion efficiency
This research explores the photofermentation of glycerol to hydrogen by Rhodopseudomonas palus-
tris, with the objective to maximise hydrogen production. Two piecewise models are designed to
simulate the entire growth phase of R. palustris; a challenge that few dynamic models can accomplish.
The parameters in both models were fitted by the present batch experiments through the
solution of the underlying optimal control problems by means of stable and accurate discretisation
techniques. It was found that an initial glutamate to glycerol ratio of 0.25 was optimal, and
was independent of the initial biomass concentration. The glycerol conversion efficiency was found
to depend on initial biomass concentration and its computational peak is 64.4%. By optimising
a 30-day industrially relevant batch process, the hydrogen productivity was improved to be 37.7
mL·g biomass-1·hr-1 and the glycerol conversion efficiency was maintained at 58%. The models can
then be applied as the connection to transfer biohydrogen production from laboratory scale into
industrial scale.Authors N. Xiao and
Dr. K. T. Mahbubani are funded through the KACST-Cambridge Center for Advanced Material
Manufacture, the author E. A. del Rio-Chanona is found by CONACyT scholarship No. 522530
from the Secretariat of Public Education and the Mexican government.This is the accepted manuscript. The final version is available from Elsevier at http://www.sciencedirect.com/science/article/pii/S0009250915001815
On the Origin of the -4.4 eV Band in CdTe(100)"
We calculate the bulk- (infinite system), (100)-bulk-projected- and
(100)-Surface-projected Green's functions using the Surface Green's Function
Matching method (SGFM) and an empirical tight-binding hamiltonian with
tight-binding parameters (TBP) that describe well the bulk band structure of
CdTe. In particular, we analyze the band (B--4) arising at --4.4 eV from the
top of the valence band at according to the results of Niles and
H\"ochst and at -4.6 eV according to Gawlik {\it et al.} both obtained by
Angle-resolved photoelectron spectroscopy (ARPES). We give the first
theoretical description of this band.Comment: 17 pages, Rev-TEX, CIEA-Phys. 02/9
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