5,136 research outputs found
Twenty years later: Still walking to Xanadu
Se analiza el poema "Kubla Khan" de Coleridge y su proceso creativo. En conjunto, el poema recuerda al antiguo mito griego de Prometeo, el semidiós que hizo al hombre de barro, robó el fuego del Olimpo. Finalmente fue castigado por su arrogancia y encadenado por Zeus. El espíritu humano es incompleto y lleno de fallos, por lo tanto, debe ser la verdadera ambición de cada genio poético elevarse por encima del hombre y obtener del cielo el toque de perfección que hace su trabajo atemporal y eterno.Coleridge's poem "Kubla Khan", and his creative process is analyzed. The poem reminds strongly of the ancient Greek myth of Prometheus, the demigod who made man from clay, stole fire from Olympus and taught men the use of it. Finally he was punished for his hubris and chained by Zeus. The normal human spirit is incomplete and full of faults. Therefore it must be the true ambition of every poetical genius to rise above man and to obtain from heaven the touch of perfection which alone makes his work timeless and everlasting
Quantum Spin Hall Insulator State in HgTe Quantum Wells
Recent theory predicted that the Quantum Spin Hall Effect, a fundamentally
novel quantum state of matter that exists at zero external magnetic field, may
be realized in HgTe/(Hg,Cd)Te quantum wells. We have fabricated such sample
structures with low density and high mobility in which we can tune, through an
external gate voltage, the carrier conduction from n-type to the p-type,
passing through an insulating regime. For thin quantum wells with well width d
< 6.3 nm, the insulating regime shows the conventional behavior of vanishingly
small conductance at low temperature. However, for thicker quantum wells (d >
6.3 nm), the nominally insulating regime shows a plateau of residual
conductance close to 2e^2/h. The residual conductance is independent of the
sample width, indicating that it is caused by edge states. Furthermore, the
residual conductance is destroyed by a small external magnetic field. The
quantum phase transition at the critical thickness, d = 6.3 nm, is also
independently determined from the magnetic field induced insulator to metal
transition. These observations provide experimental evidence of the quantum
spin Hall effect.Comment: 16 pages, 5 figure
Conductance plateau in quantum spin transport through an interacting quantum dot
Quantum spin transport is studied in an interacting quantum dot. It is found
that a conductance "plateau" emerges in the non-linear charge conductance by a
spin bias in the Kondo regime. The conductance plateau, as a complementary to
the Kondo peak, originates from the strong electron correlation and exchange
processes in the quantum dot, and can be regarded as one of the characteristics
in quantum spin transport.Comment: 5 pages, 5 figure
Decay in the Left-Right Supersymmetric Model
We calculate the rate of the decay and the electric dipole
moment of the electron in the left-right supersymmetric model when the breaking
of parity occurs at a considerably large scale. The low-energy flavor violation
in the model originates either from the nonvanishing remnants of the left-right
symmetry in the slepton mass matrix or from the direct flavor changing
lepton-slepton-neutralino interaction. The result is found to be large for the
masses of the supersymmetric particles not far from the electroweak scale and
already accessible at the current experimental accuracy. It also provides
nontrivial constraints of the lepton mixing in the model.Comment: 10 pages, LaTeX, 1 figur
Evaluation of aircraft microwave data for locating zones for well stimulation and enhanced gas recovery
Imaging radar was evaluated as an adjunct to conventional petroleum exploration techniques, especially linear mapping. Linear features were mapped from several remote sensor data sources including stereo photography, enhanced LANDSAT imagery, SLAR radar imagery, enhanced SAR radar imagery, and SAR radar/LANDSAT combinations. Linear feature maps were compared with surface joint data, subsurface and geophysical data, and gas production in the Arkansas part of the Arkoma basin. The best LANDSAT enhanced product for linear detection was found to be a winter scene, band 7, uniform distribution stretch. Of the individual SAR data products, the VH (cross polarized) SAR radar mosaic provides for detection of most linears; however, none of the SAR enhancements is significantly better than the others. Radar/LANDSAT merges may provide better linear detection than a single sensor mapping mode, but because of operator variability, the results are inconclusive. Radar/LANDSAT combinations appear promising as an optimum linear mapping technique, if the advantages and disadvantages of each remote sensor are considered
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