761 research outputs found
Pre-processing Algorithm for Rectification of Geometric Distortions in Satellite Images
A number of algorithms have been reported to process and remove geometric distortions in satellite images. Ortho-correction, geometric error correction, radiometric error removal, etc are a few important examples. These algorithm require supplementary meta-information of the satellite images such as ground control points and correspondence, sensor orientation details, elevation profile of the terrain, etc to establish corresponding transformations. In this paper, a pre-processing algorithm has been proposed which removes systematic distortions of a satellite image and thereby removes the blank portion of the image. It is an input-to-output mapping of image pixels, where the transformation computes the coordinate of each output pixel corresponding to the input pixel of an image. The transformation is established by the exact amount of scaling, rotation and translation needed for each pixel in the input image so that the distortion induced during the recording stage is corrected.Defence Science Journal, 2011, 61(2), pp.174-179, DOI:http://dx.doi.org/10.14429/dsj.61.42
Bound State Wave Functions through the Quantum Hamilton - Jacobi Formalism
The bound state wave functions for a wide class of exactly solvable
potentials are found utilizing the quantum Hamilton-Jacobi formalism. It is
shown that, exploiting the singularity structure of the quantum momentum
function, until now used only for obtaining the bound state energies, one can
straightforwardly find both the eigenvalues and the corresponding
eigenfunctions. After demonstrating the working of this approach through a
number of solvable examples, we consider Hamiltonians, which exhibit broken and
unbroken phases of supersymmetry. The natural emergence of the eigenspectra and
the wave functions, in both the unbroken and the algebraically non-trivial
broken phase, demonstrates the utility of this formalism.Comment: replaced with the journal versio
Optical absorption and photoluminescence spectroscopy of the growth of silver nanoparticles
Results obtained from the optical absorption and photoluminescence (PL)
spectroscopy experiments have shown the formation of excitons in the
silver-exchanged glass samples. These findings are reported here for the first
time. Further, we investigate the dramatic changes in the photoemission
properties of the silver-exchanged glass samples as a function of postannealing
temperature. Observed changes are thought to be due to the structural
rearrangements of silver and oxygen bonding during the heat treatments of the
glass matrix. In fact, photoelectron spectroscopy does reveal these chemical
transformations of silver-exchanged soda glass samples caused by the thermal
effects of annealing in a high vacuum atmosphere. An important correlation
between temperature-induced changes of the PL intensity and thermal growth of
the silver nanoparticles has been established in this Letter through precise
spectroscopic studies.Comment: 15 pages,4 figures,PDF fil
Sinusoidal Excitations in Two Component Bose-Einstein Condensates
The non-linear coupled Gross-Pitaevskii equation governing the dynamics of
the two component Bose-Einstein condensate (TBEC) is shown to admit pure
sinusoidal, propagating wave solutions in quasi one dimensional geometry. These
solutions, which exist for a wide parameter range, are then investigated in the
presence of a harmonic oscillator trap with time dependent scattering length.
This illustrates the procedure for coherent control of these modes through
temporal modulation of the parameters, like scattering length and oscillator
frequency. We subsequently analyzed this system in an optical lattice, where
the occurrence of an irreversible phase transition from superfluid to insulator
phase is seen.Comment: 6 pages, 1 figur
Canonical steering ellipsoids of pure symmetric multiqubit states with two distinct spinors and volume monogamy of steering
Quantum steering ellipsoid formalism provides a faithful representation of
all two-qubit states and helps in obtaining correlation properties of the state
through the steering ellipsoid. The steering ellipsoids corresponding to the
two-qubit subsystems of permutation symmetric -qubit states is analysed
here. The steering ellipsoids of two-qubit states that have undergone local
operations on both the qubits so as to bring the state to its canonical form
are the so-called canonical steering ellipsoids. We construct and analyze the
geometric features of the canonical steering ellipsoids corresponding to pure
permutation symmetric -qubit states with two distinct spinors. Depending on
the degeneracy of the two spinors in the pure symmetric -qubit state, there
arise several families which cannot be converted into one another through
Stochastic Local Operations and Classical Communications (SLOCC). The canonical
steering ellipsoids of the two-qubit states drawn from the pure symmetric
-qubit states with two distinct spinors allow for a geometric visualization
of the SLOCC-inequivalent class of states. We show that the states belonging to
the W-class correspond to oblate spheroid centered at with
fixed semiaxes lengths and . The states belonging to
all other SLOCC inequivalent families correspond to ellipsoids centered at the
origin of the Bloch sphere. We also explore volume monogamy relations of states
belonging to these families, mainly the W-class of states.Comment: 13 pages, 13 figures; Revised version; Comments welcom
Arabidopsis DOF Transcription Factors Act Redundantly to Reduce CONSTANS Expression and Are Essential for a Photoperiodic Flowering Response
SummaryFlowering of Arabidopsis is induced by long summer days (LDs). The transcriptional regulator CONSTANS (CO) promotes flowering, and its transcription is increased under LDs. We systematically misexpressed transcription factors in companion cells and identified several DOF proteins that delay flowering by repressing CO transcription. Combining mutations in four of these, including CYCLING DOF FACTOR 2 (CDF2), caused photoperiod-insensitive early flowering by increasing CO mRNA levels. CO transcription is promoted to differing extents by GIGANTEA (GI) and the F-box protein FKF1. We show that GI stabilizes FKF1, thereby reducing CDF2 abundance and allowing transcription of CO. Despite the crucial function of GI in wild-type plants, introducing mutations in the four DOF-encoding genes into gi mutants restored the diurnal rhythm and light inducibility of CO. Thus, antagonism between GI and DOF transcription factors contributes to photoperiodic flowering by modulating an underlying diurnal rhythm in CO transcript levels
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