598 research outputs found
Assessment of MISR and MODIS cloud top heights through inter-comparison with a back-scattering lidar at SIRTA
One year of back-scattering lidar cloud boundaries and optical depth were analysed for coincident inter-comparison with the latest processed versions of the NASA-TERRA MISR stereo and MODIS CO2-slicing operational cloud top heights. Optically thin clouds were found to be accurately characterised by the MISR cloud top height product as long as no other cloud was present at lower altitude. MODIS cloud top heights were generally found within the cloud extent retrieved by lidar; agreement improved as cloud optical depth increased and when CO2-slicing was the only technique used for the retrieval. The difference between Lidar and MISR cloud top heights was found to lie between −0.1 and 0.4 km for low clouds and between 0.1 and 3.1 km for high clouds. The difference between Lidar and MODIS cloud top heights was found to lie between −1.2 and 1.5 km for low clouds and between −1.4 and 2.7 km for high clouds
Aharonov-Bohm cages in the GaAlAs/GaAs system
Aharonov-Bohm oscillations have been observed in a lattice formed by a two
dimensional rhombus tiling. This observation is in good agreement with a recent
theoretical calculation of the energy spectrum of this so-called T3 lattice. We
have investigated the low temperature magnetotransport of the T3 lattice
realized in the GaAlAs/GaAs system. Using an additional electrostatic gate, we
have studied the influence of the channel number on the oscillations amplitude.
Finally, the role of the disorder on the strength of the localization is
theoretically discussed.Comment: 6 pages, 11 EPS figure
A V-shape superconducting artificial atom based on two inductively coupled transmons
Circuit quantum electrodynamics systems are typically built from resonators
and two-level artificial atoms, but the use of multi-level artificial atoms
instead can enable promising applications in quantum technology. Here we
present an implementation of a Josephson junction circuit dedicated to operate
as a V-shape artificial atom. Based on a concept of two internal degrees of
freedom, the device consists of two transmon qubits coupled by an inductance.
The Josephson nonlinearity introduces a strong diagonal coupling between the
two degrees of freedom that finds applications in quantum non-demolition
readout schemes, and in the realization of microwave cross-Kerr media based on
superconducting circuits.Comment: 5 pages, 3 figure
Regional ion channel gene expression heterogeneity and ventricular fibrillation dynamics in human hearts.
RATIONALE: Structural differences between ventricular regions may not be the sole determinant of local ventricular fibrillation (VF) dynamics and molecular remodeling may play a role. OBJECTIVES: To define regional ion channel expression in myopathic hearts compared to normal hearts, and correlate expression to regional VF dynamics. METHODS AND RESULTS: High throughput real-time RT-PCR was used to quantify the expression patterns of 84 ion-channel, calcium cycling, connexin and related gene transcripts from sites in the LV, septum, and RV in 8 patients undergoing transplantation. An additional eight non-diseased donor human hearts served as controls. To relate local ion channel expression change to VF dynamics localized VF mapping was performed on the explanted myopathic hearts right adjacent to sampled regions. Compared to non-diseased ventricles, significant differences (p<0.05) were identified in the expression of 23 genes in the myopathic LV and 32 genes in the myopathic RV. Within the myopathic hearts significant regional (LV vs septum vs RV) expression differences were observed for 13 subunits: Nav1.1, Cx43, Ca3.1, Cavalpha2delta2, Cavbeta2, HCN2, Na/K ATPase-1, CASQ1, CASQ2, RYR2, Kir2.3, Kir3.4, SUR2 (p<0.05). In a subset of genes we demonstrated differences in protein expression between control and myopathic hearts, which were concordant with the mRNA expression profiles for these genes. Variability in the expression of Cx43, hERG, Na(+)/K(+) ATPase ss1 and Kir2.1 correlated to variability in local VF dynamics (p<0.001). To better understand the contribution of multiple ion channel changes on VF frequency, simulations of a human myocyte model were conducted. These simulations demonstrated the complex nature by which VF dynamics are regulated when multi-channel changes are occurring simultaneously, compared to known linear relationships. CONCLUSIONS: Ion channel expression profile in myopathic human hearts is significantly altered compared to normal hearts. Multi-channel ion changes influence VF dynamic in a complex manner not predicted by known single channel linear relationships
Alteration of superconductivity of suspended carbon nanotubes by deposition of organic molecules
We have altered the superconductivity of a suspended rope of single walled
carbon nanotubes, by coating it with organic polymers. Upon coating, the normal
state resistance of the rope changes by less than 20 percent. But
superconductivity, which on the bare rope shows up as a substantial resistance
decrease below 300 mK, is gradualy suppressed. We correlate this to the
suppression of radial breathing modes, measured with Raman Spectroscopy on
suspended Single and Double-walled carbon nanotubes. This points to the
breathing phonon modes as being responsible for superconductivity in carbon
nanotubes
Computer-Assisted Generation of Patterns and Virtual Reality Techniques for Fashion Design
We present a methodology for the design of aesthetic patterns and their visualization on virtual clothes. Generated patterns are directly mapped on the dress of a virtual mannequin. Furthermore, patterns sets may be interactively mapped on the virtual dress using a specific 3D interaction technique called Back-and-Forth. Pattern generation involves different mathematical approaches such as iterated function systems (IFS) and nonlinear trajectory models. Both model parameters and color space exploration is performed through a simple user interface. This work contributes to promote both computer assistance in the context of mass customization for fashion design
Probing Spin-Charge Separation in Tunnel-Coupled Parallel Quantum Wires
Interactions in one-dimensional (1D) electron systems are expected to cause a
dynamical separation of electronic spin and charge degrees of freedom. A
promising system for experimental observation of this non-Fermi-liquid effect
consists of two quantum wires coupled via tunneling through an extended uniform
barrier. Here we consider the minimal model of an interacting 1D electron
system exhibiting spin-charge separation and calculate the differential
tunneling conductance as well as the density-density response function. Both
quantities exhibit distinct strong features arising from spin-charge
separation. Our analysis of these features within the minimal model neglects
interactions between electrons of opposite chirality and applies therefore
directly to chiral 1D electron systems realized, e.g., at the edge of integer
quantum-Hall systems. Physical insight gained from our results is useful for
interpreting current experiment in quantum wires as our main conclusions still
apply with nonchiral interactions present. In particular, we discuss the effect
of charging due to applied voltages, and the possibility to observe spin-charge
separation in a time-resolved experiment.Comment: 9 pages, 3 figures, expanded version with many detail
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