5,922 research outputs found
ESMO Minimum Clinical Recommendations for diagnosis, treatment and follow-up of pancreatic cancer
Temporal solitons in optical microresonators
Dissipative solitons can emerge in a wide variety of dissipative nonlinear
systems throughout the fields of optics, medicine or biology. Dissipative
solitons can also exist in Kerr-nonlinear optical resonators and rely on the
double balance between parametric gain and resonator loss on the one hand and
nonlinearity and diffraction or dispersion on the other hand. Mathematically
these solitons are solution to the Lugiato-Lefever equation and exist on top of
a continuous wave (cw) background. Here we report the observation of temporal
dissipative solitons in a high-Q optical microresonator. The solitons are
spontaneously generated when the pump laser is tuned through the effective zero
detuning point of a high-Q resonance, leading to an effective red-detuned
pumping. Red-detuned pumping marks a fundamentally new operating regime in
nonlinear microresonators. While usually unstablethis regime acquires unique
stability in the presence of solitons without any active feedback on the
system. The number of solitons in the resonator can be controlled via the pump
laser detuning and transitions to and between soliton states are associated
with discontinuous steps in the resonator transmission. Beyond enabling to
study soliton physics such as soliton crystals our observations open the route
towards compact, high repetition-rate femto-second sources, where the operating
wavelength is not bound to the availability of broadband laser gain media. The
single soliton states correspond in the frequency domain to low-noise optical
frequency combs with smooth spectral envelopes, critical to applications in
broadband spectroscopy, telecommunications, astronomy and low phase-noise
microwave generation.Comment: Includes Supplementary Informatio
Hamiltonian equation of motion and depinning phase transition in two-dimensional magnets
Based on the Hamiltonian equation of motion of the theory with
quenched disorder, we investigate the depinning phase transition of the
domain-wall motion in two-dimensional magnets. With the short-time dynamic
approach, we numerically determine the transition field, and the static and
dynamic critical exponents. The results show that the fundamental Hamiltonian
equation of motion belongs to a universality class very different from those
effective equations of motion.Comment: 6 pages, 7 figures, have been accept by EP
Correlation in states of two identical particles
We identify the correlation in a state of two identical particles as the
residual information beyond what is already contained in the 1-particle reduced
density matrix, and propose a correlation measure based on the maximum entropy
principle. We obtain the analytical results of the correlation measure, which
make it computable for arbitrary two-particle states. We also show that the
degrees of correlation in the same two-particle states with different particle
types will decrease in the following order: bosons, fermions, and
distinguishable particles.Comment: 3.6 page
Cardiac remodeling accompanied by increased arrhythmia susceptibility in a dog model of chronic high-intensity endurance training : [abstract]
Anisotropic and strong negative magneto-resistance in the three-dimensional topological insulator Bi2Se3
We report on high-field angle-dependent magneto-transport measurements on
epitaxial thin films of Bi2Se3, a three-dimensional topological insulator. At
low temperature, we observe quantum oscillations that demonstrate the
simultaneous presence of bulk and surface carriers. The magneto- resistance of
Bi2Se3 is found to be highly anisotropic. In the presence of a parallel
electric and magnetic field, we observe a strong negative longitudinal
magneto-resistance that has been consid- ered as a smoking-gun for the presence
of chiral fermions in a certain class of semi-metals due to the so-called axial
anomaly. Its observation in a three-dimensional topological insulator implies
that the axial anomaly may be in fact a far more generic phenomenon than
originally thought.Comment: 6 pages, 4 figure
Discrete Symmetries and Localization in a Brane-world
Discrete symmetries are studied in warped space-times with one extra
dimension. In particular, we analyze the compatibility of five- and
four-dimensional charge conjugation, parity, time reversal and the orbifold
symmetry Z_2 with localization of fermions on the four-dimensional brane-world
and Lorentz invariance. We then show that, when a suitable topological scalar
field (the ``kink'') is included, fermion localization is a consequence of
(five-dimensional) CPT invariance.Comment: REVTeX, 8 pages, 1 EPS figure include
Axiomatic formulations of nonlocal and noncommutative field theories
We analyze functional analytic aspects of axiomatic formulations of nonlocal
and noncommutative quantum field theories. In particular, we completely clarify
the relation between the asymptotic commutativity condition, which ensures the
CPT symmetry and the standard spin-statistics relation for nonlocal fields, and
the regularity properties of the retarded Green's functions in momentum space
that are required for constructing a scattering theory and deriving reduction
formulas. This result is based on a relevant Paley-Wiener-Schwartz-type theorem
for analytic functionals. We also discuss the possibility of using analytic
test functions to extend the Wightman axioms to noncommutative field theory,
where the causal structure with the light cone is replaced by that with the
light wedge. We explain some essential peculiarities of deriving the CPT and
spin-statistics theorems in this enlarged framework.Comment: LaTeX, 13 pages, no figure
The massive analytic invariant charge in QCD
The low energy behavior of a recently proposed model for the massive analytic
running coupling of QCD is studied. This running coupling has no unphysical
singularities, and in the absence of masses displays infrared enhancement. The
inclusion of the effects due to the mass of the lightest hadron is accomplished
by employing the dispersion relation for the Adler D function. The presence of
the nonvanishing pion mass tames the aforementioned enhancement, giving rise to
a finite value for the running coupling at the origin. In addition, the
effective charge acquires a "plateau-like" behavior in the low energy region of
the timelike domain. This plateau is found to be in agreement with a number of
phenomenological models for the strong running coupling. The developed
invariant charge is applied in the processing of experimental data on the
inclusive lepton decay. The effects due to the pion mass play an
essential role here as well, affecting the value of the QCD scale parameter
extracted from these data. Finally, the massive analytic running
coupling is compared with the effective coupling arising from the study of
Schwinger-Dyson equations, whose infrared finiteness is due to a dynamically
generated gluon mass. A qualitative picture of the possible impact of the
former coupling on the chiral symmetry breaking is presented.Comment: 13 pages, 7 figures, revtex
Depinning transition and thermal fluctuations in the random-field Ising model
We analyze the depinning transition of a driven interface in the 3d
random-field Ising model (RFIM) with quenched disorder by means of Monte Carlo
simulations. The interface initially built into the system is perpendicular to
the [111]-direction of a simple cubic lattice. We introduce an algorithm which
is capable of simulating such an interface independent of the considered
dimension and time scale. This algorithm is applied to the 3d-RFIM to study
both the depinning transition and the influence of thermal fluctuations on this
transition. It turns out that in the RFIM characteristics of the depinning
transition depend crucially on the existence of overhangs. Our analysis yields
critical exponents of the interface velocity, the correlation length, and the
thermal rounding of the transition. We find numerical evidence for a scaling
relation for these exponents and the dimension d of the system.Comment: 6 pages, including 9 figures, submitted for publicatio
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