2,722 research outputs found
Investigation of natural environment by space means. Geobotany, Geomorphology, soil sciences, agricultural lands, landscape study
Reports given by Soviet specialists at a meeting of Socialist countries on remote sensing of the earth using aerospace methods are presented
Photovoltage in curved 1D systems
Curvature of quantum wire results in intrasubband absorption of
IR radiation that induces stationary photovoltage in presence of circular
polarization. This effect is studied in ballistic (collisionless) and kinetic
regimes. The consideration is concentrated on quantum wires with curved central
part. It is shown, that if mean free path is shorter than length of the curved
part the photovoltage does not depend on the wire shape, but on the total angle
of rotation of wire tangent. It is not the case when mean free path is finite
or large. This situation was studied for three specific shapes of wires: "hard
angle", "open book" and "-like".Comment: 12 pages, 1 figur
The algebra of extended peaks
Building up on our previous works regarding -deformed -partitions, we
introduce a new family of subalgebras for the ring of quasisymmetric functions.
Each of these subalgebras admits as a basis a -analogue to Gessel's
fundamental quasisymmetric functions where is equal to a complex root of
unity. Interestingly, the basis elements are indexed by sets corresponding to
an intermediary statistic between peak and descent sets of permutations that we
call extended peak.Comment: 12 pages; extended abstract submitted for FPSAC. Longform papers on
the project are still forthcomin
X-ray Reflection Spectroscopy of the Black Hole GX 339-4: Exploring the Hard State with Unprecedented Sensitivity
We analyze {\it simultaneously} six composite {\it RXTE} spectra of GX 339--4
in the hard state comprising 77 million counts collected over 196 ks. The
source spectra are ordered by luminosity and spanthe range 1.6\% to 17\% of the
Eddington luminosity. Crucially, using our new tool {\tt pcacorr}, we
re-calibrate the data to a precision of 0.1\%, an order of magnitude
improvement over all earlier work. Using our advanced reflection model {\tt
relxill}, we target the strong features in the component of emission reflected
from the disk, namely, the relativistically-broadened Fe K emission line, the
Fe K edge and the Compton hump. We report results for two joint fits to the six
spectra: For the first fit, we fix the spin parameter to its maximal value
() and allow the inner disk radius to vary. Results
include (i) precise measurements of , with evidence that the disk
becomes slightly truncated at a few percent of Eddington; and (ii) an
order-of-magnitude swing with luminosity in the high energy cutoff, which
reaches keV at our lowest luminosity. For the second fit, we make the
standard assumption in estimating spin that the inner edge of the accretion
disk is located at the innermost stable circular orbit () and find (90\% confidence,
statistical). For both fits, and at the same level of statistical confidence,
we estimate that the disk inclination is deg and that the Fe
abundance is super-solar, .Comment: Accepted for publication in ApJ, 20 pages, 13 figure
The enriched -monomial basis of the quasisymmetric functions
We construct a new family of quasisymmetric functions for each element
of the base ring. We call them the "enriched -monomial quasisymmetric
functions". When is invertible, this family is a basis of
. It generalizes Hoffman's "essential quasi-symmetric
functions" (obtained for ) and Hsiao's "monomial peak functions" (obtained
for ), but also includes the monomial quasisymmetric functions as a
limiting case.
We describe these functions by several
formulas, and compute their products, coproducts and antipodes. The product
expansion is given by an exotic variant of the shuffle product which we call
the "stufufuffle product" due to its ability to pick several consecutive
entries from each composition. This "stufufuffle product" has previously
appeared in recent work by Bouillot, Novelli and Thibon, generalizing the
"block shuffle product" from the theory of multizeta values.Comment: 106 pages. A shortened version for more advanced readers will soon be
submitted. Comments are welcome
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