43,327 research outputs found
Evolution of emotions on networks leads to the evolution of cooperation in social dilemmas
We show that the resolution of social dilemmas in random graphs and scale-free networks is facilitated by
imitating not the strategy of better-performing players but, rather, their emotions. We assume sympathy and
envy to be the two emotions that determine the strategy of each player in any given interaction, and we define
them as the probabilities of cooperating with players having a lower and a higher payoff, respectively. Starting
with a population where all possible combinations of the two emotions are available, the evolutionary process
leads to a spontaneous fixation to a single emotional profile that is eventually adopted by all players. However,
this emotional profile depends not only on the payoffs but also on the heterogeneity of the interaction network.
Homogeneous networks, such as lattices and regular random graphs, lead to fixations that are characterized by
high sympathy and high envy, while heterogeneous networks lead to low or modest sympathy but also low envy.
Our results thus suggest that public emotions and the propensity to cooperate at large depend, and are in fact
determined by, the properties of the interaction network
Inducing ferromagnetism and Kondo effect in platinum by paramagnetic ionic gating
Electrically controllable magnetism, which requires the field-effect
manipulation of both charge and spin degrees of freedom, has attracted growing
interests since the emergence of spintronics. In this work, we report the
reversible electrical switching of ferromagnetic (FM) states in platinum (Pt)
thin films by introducing paramagnetic ionic liquid (PIL) as the gating media.
The paramagnetic ionic gating controls the movement of ions with magnetic
moments, which induces itinerant ferromagnetism on the surface of Pt films with
large coercivity and perpendicular anisotropy mimicking the ideal
two-dimensional Ising-type FM state. The electrical transport of the induced FM
state shows Kondo effect at low temperature suggesting spatially separated
coexistence of Kondo scattering beneath the FM interface. The tunable FM state
indicates that paramagnetic ionic gating could serve as a versatile method to
induce rich transport phenomena combining field effect and magnetism at
PIL-gated interfaces.Comment: 17 pages, 4 figure
Real-time cavity QED with single atoms
We report the first measurement of the real-time evolution of the complex field amplitude brought on by single atom transits. We show the variation in time of both quadrature amplitudes (simultaneously recorded) of the light transmitted through the cavity, as well the resultant optical phase for a single atom transit event. In this particular measurement, the cavity and laser were both detuned by 10 MHz from the Cs resonance
DNA-decorated graphene chemical sensors
Graphene is a true two dimensional material with exceptional electronic
properties and enormous potential for practical applications. Graphene's
promise as a chemical sensor material has been noted but there has been
relatively little work on practical chemical sensing using graphene, and in
particular how chemical functionalization may be used to sensitize graphene to
chemical vapors. Here we show one route towards improving the ability of
graphene to work as a chemical sensor by using single stranded DNA as a
sensitizing agent. The resulting broad response devices show fast response
times, complete and rapid recovery to baseline at room temperature, and
discrimination between several similar vapor analytes.Comment: 7 pages, To appear in Applied Physics Letter
Two Dimensional Ising Superconductivity in Gated MoS
The Zeeman effect, which is usually considered to be detrimental to
superconductivity, can surprisingly protect the superconducting states created
by gating a layered transition metal dichalcogenide. This effective Zeeman
field, which is originated from intrinsic spin orbit coupling induced by
breaking in-plane inversion symmetry, can reach nearly a hundred Tesla in
magnitude. It strongly pins the spin orientation of the electrons to the
out-of-plane directions and protects the superconductivity from being destroyed
by an in-plane external magnetic field. In magnetotransport experiments of
ionic-gate MoS transistors, where gating prepares individual
superconducting state with different carrier doping, we indeed observe a spin-
protected superconductivity by measuring an in-plane critical field
far beyond the Pauli paramagnetic limit. The
gating-enhanced is more than an order of magnitude larger
compared to the bulk superconducting phases where the effective Zeeman field is
weakened by interlayer coupling. Our study gives the first experimental
evidence of an Ising superconductor, in which spins of the pairing electrons
are strongly pinned by an effective Zeeman field
Extreme Nonlinear Optics in a Femtosecond Enhancement Cavity
Intrinsic to the process of high-order harmonic generation is the creation of
plasma and the resulting spatiotemporal distortions of the driving laser pulse.
Inside a high finesse cavity where the driver pulse and gas medium are reused,
this can lead to optical bistability of the cavity-plasma system, accumulated
self-phase modulation of the intracavity pulse, and coupling to higher order
cavity modes. We present an experimental and theoretical study of these effects
and discuss their implications for power scaling of intracavity high-order
harmonic generation and extreme ultraviolet frequency combs
Far Ultraviolet Spectroscopic Explorer Observations of a Supernova Remnant in the Line of Sight to HD 5980 in the Small Magellanic Cloud
We report a detection of far ultraviolet absorption from the supernova
remnant SNR 0057 - 7226 in the Small Magellanic Cloud (SMC). The absorption is
seen in the Far Ultraviolet Spectroscopic Explorer (FUSE) spectrum of the
LBV/WR star HD 5980. Absorption from O VI 1032 and C III 977 is seen at a
velocity of +300 km/s with respect to the Galactic absorption lines, +170 km/s
with respect to the SMC absorption. The O VI 1038 line is contaminated by H_2
absorption, but is present. These lines are not seen in the FUSE spectrum of
Sk80, only ~1' (~17 pc) away from HD 5980. No blue-shifted O VI 1032 absorption
from the SNR is seen in the FUSE spectrum. The O VI 1032 line in the SNR is
well described by a Gaussian with FWHM=75 km/s. We find log N(O
VI)=14.33-14.43, which is roughly 50% of the rest of the O VI column in the SMC
(excluding the SNR) and greater than the O VI column in the Milky Way halo
along this sight line. The N(C IV)/N(O VI) ratio for the SNR absorption is in
the range of 0.12-0.17, similar to the value seen in the Milky Way disk, and
lower than the halo value, supporting models in which SNRs produce the highly
ionized gas close to the plane of the Galaxy, while other mechanisms occur in
the halo. The N(C IV)/N(O VI) ratio is also lower than the SMC ratio along this
sight line, suggesting that other mechanisms contribute to the creation of the
global hot ionized medium in the SMC. The O VI, C IV, and Si IV apparent column
density profiles suggest the presence of a multi-phase shell followed by a
region of higher temperature gas.Comment: 7 pages, 3 figures, 2 tables, uses emulateapj5.sty. Accepted for
publication in ApJ Letter
Statistical Models of Reconstructed Phase Spaces for Signal Classification
This paper introduces a novel approach to the analysis and classification of time series signals using statistical models of reconstructed phase spaces. With sufficient dimension, such reconstructed phase spaces are, with probability one, guaranteed to be topologically equivalent to the state dynamics of the generating system, and, therefore, may contain information that is absent in analysis and classification methods rooted in linear assumptions. Parametric and nonparametric distributions are introduced as statistical representations over the multidimensional reconstructed phase space, with classification accomplished through methods such as Bayes maximum likelihood and artificial neural networks (ANNs). The technique is demonstrated on heart arrhythmia classification and speech recognition. This new approach is shown to be a viable and effective alternative to traditional signal classification approaches, particularly for signals with strong nonlinear characteristics
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