14,369 research outputs found
Semiempirical Modeling of Reset Transitions in Unipolar Resistive-Switching based Memristors
We have measured the transition process from the high to low resistivity states, i.e., the reset process of resistive switching based memristors based on Ni/HfO2/Si-n+ structures, and have also developed an analytical model for their electrical characteristics. When the characteristic curves are plotted in the current-voltage (I-V) domain a high variability is observed. In spite of that, when the same curves are plotted in the charge-flux domain (Q-phi), they can be described by a simple model containing only three parameters: the charge (Qrst) and the flux (rst) at the reset point, and an exponent, n, relating the charge and the flux before the reset transition. The three parameters can be easily extracted from the Q-phi plots. There is a strong correlation between these three parameters, the origin of which is still under study
Harvesting Excitons Through Plasmonic Strong Coupling
Exciton harvesting is demonstrated in an ensemble of quantum emitters coupled
to localized surface plasmons. When the interaction between emitters and the
dipole mode of a metallic nanosphere reaches the strong coupling regime, the
exciton conductance is greatly increased. The spatial map of the conductance
matches the plasmon field intensity profile, which indicates that transport
properties can be tuned by adequately tailoring the field of the plasmonic
resonance. Under strong coupling, we find that pure dephasing can have
detrimental or beneficial effects on the conductance, depending on the
effective number of participating emitters. Finally, we show that the exciton
transport in the strong coupling regime occurs on an ultrafast timescale given
by the inverse Rabi splitting (fs), orders of magnitude faster than
transport through direct hopping between the emitters.Comment: 5 pages, 3 figure
U B V R I Photometry of Stellar Structures throughout the Disk of the Barred Galaxy NGC 3367
We report new detailed surface U, B, V, R, and I photometry of 81 stellar
structures in the disk of the barred galaxy NGC 3367. The images show many
different structures indicating that star formation is going on in the most
part of the disk. NGC 3367 is known to have a very high concentration of
molecular gas distribution in the central regions of the galaxy and bipolar
synchrotron emission from the nucleus with two lobes (at 6 kpc) forming a
triple structure similar to a radio galaxy. We have determined the U, B, V, R,
and I magnitudes and U - B, B - V, U - V, and V - I colors for the central
region (nucleus), a region which includes supernovae 2003 AA, and 79 star
associations throughout NGC 3367. Estimation of ages of star associations is
very difficult due to several factors, among them: filling factor, metallicity,
spatial distribution of each structure and the fact that we estimated the
magnitudes with a circular aperture of 16 pixels in diameter, equivalent to
kpc. However, if the colors derived for NGC 3367 were similar to
the colors expected of star clusters with theoretical evolutionary star tracks
developed for the LMC and had a similar metallicity, NGC 3367 show 51 percent
of the observed structures with age type SWB I (few tens of Myrs), with seven
sources outside the bright surface brightness visible disk of NGC 3367.Comment: Accepted for publication (abr 2007) in The Astronomical Journal (July
2007 issue
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