1,062 research outputs found
Macroscopic Noisy Bounded Confidence Models with Distributed Radical Opinions
In this article, we study the nonlinear Fokker-Planck (FP) equation that
arises as a mean-field (macroscopic) approximation of bounded confidence
opinion dynamics, where opinions are influenced by environmental noises and
opinions of radicals (stubborn individuals). The distribution of radical
opinions serves as an infinite-dimensional exogenous input to the FP equation,
visibly influencing the steady opinion profile. We establish mathematical
properties of the FP equation. In particular, we (i) show the well-posedness of
the dynamic equation, (ii) provide existence result accompanied by a
quantitative global estimate for the corresponding stationary solution, and
(iii) establish an explicit lower bound on the noise level that guarantees
exponential convergence of the dynamics to stationary state. Combining the
results in (ii) and (iii) readily yields the input-output stability of the
system for sufficiently large noises. Next, using Fourier analysis, the
structure of opinion clusters under the uniform initial distribution is
examined. Specifically, two numerical schemes for identification of
order-disorder transition and characterization of initial clustering behavior
are provided. The results of analysis are validated through several numerical
simulations of the continuum-agent model (partial differential equation) and
the corresponding discrete-agent model (interacting stochastic differential
equations) for a particular distribution of radicals
Field effect on surface states in a doped Mott-Insulator thin film
Surface effects of a doped thin film made of a strongly correlated material
are investigated both in the absence and presence of a perpendicular electric
field. We use an inhomogeneous Gutzwiller approximation for a single band
Hubbard model in order to describe correlation effects. For low doping, the
bulk value of the quasiparticle weight is recovered exponentially deep into the
slab, but with increasing doping, additional Friedel oscillations appear near
the surface. We show that the inverse correlation length has a power-law
dependence on the doping level. In the presence of an electrical field,
considerable changes in the quasiparticle weight can be realized throughout the
system. We observe a large difference (as large as five orders of magnitude) in
the quasiparticle weight near the opposite sides of the slab. This effect can
be significant in switching devices that use the surface states for transport
Cloning and expression of codon-optimized recombinant darbepoetin alfa in Leishmania tarentolae T7-TR
Darbepoetin alfa is an engineered and hyperglycosylated analog of recombinant human erythropoietin (EPO) which is used as a drug in treating anemia in patients with chronic kidney failure and cancer. This study desribes the secretory expression of a codon-optimized recombinant form of darbepoetin alfa in Leishmania tarentolae T7-TR. Synthetic codon-optimized gene was amplified by PCR and cloned into the pLEXSY-I-blecherry3 vector. The resultant expression vector, pLEXSYDarbo, was purified, digested, and electroporated into the L. tarentolae. Expression of recombinant darbepoetin alfa was evaluated by ELISA, reverse-transcription PCR (RT-PCR), Western blotting, and biological activity. After codon optimization, codon adaptation index (CAI) of the gene raised from 0.50 to 0.99 and its GC content changed from 56 to 58. Expression analysis confirmed the presence of a protein band at 40 kDa. Furthermore, reticulocyte experiment results revealed that the activity of expressed darbepoetin alfa was similar to that of its equivalent expressed in Chinese hamster ovary (CHO) cells. These data suggested that the codon optimization and expression in L. tarentolae host provided an efficient approach for high level expression of darbepoetin alfa. © 2015 Elsevier Ltd. All rights reserved
From Uncertainty Data to Robust Policies for Temporal Logic Planning
We consider the problem of synthesizing robust disturbance feedback policies
for systems performing complex tasks. We formulate the tasks as linear temporal
logic specifications and encode them into an optimization framework via
mixed-integer constraints. Both the system dynamics and the specifications are
known but affected by uncertainty. The distribution of the uncertainty is
unknown, however realizations can be obtained. We introduce a data-driven
approach where the constraints are fulfilled for a set of realizations and
provide probabilistic generalization guarantees as a function of the number of
considered realizations. We use separate chance constraints for the
satisfaction of the specification and operational constraints. This allows us
to quantify their violation probabilities independently. We compute disturbance
feedback policies as solutions of mixed-integer linear or quadratic
optimization problems. By using feedback we can exploit information of past
realizations and provide feasibility for a wider range of situations compared
to static input sequences. We demonstrate the proposed method on two robust
motion-planning case studies for autonomous driving
Expressing Measurement Uncertainty in OCL/UML Datatypes
Uncertainty is an inherent property of any measure or estimation performed in any physical setting, and therefore it needs to
be considered when modeling systems that manage real data. Although several modeling languages permit the representation of measurement uncertainty for describing certain system attributes, these aspects are not normally incorporated into their type systems. Thus, operating with uncertain values and propagating uncertainty are normally cumbersome processes, di cult to achieve at the model level. This paper proposes an extension of OCL and UML datatypes to incorporate data uncertainty coming from physical measurements or user estimations into the models, along with the set of operations de ned for the values of these types.Universidad de Málaga. Campus de Excelencia Internacional AndalucÃa Tech
Electrical field induced shift of the Mott Metal-Insulator transition in thin films
The ground state properties of a paramagnetic Mott insulator are investigated
in the presence of an external electrical field using the inhomogeneous
Gutzwiller approximation for a single band Hubbard model in a slab geometry.
The metal insulator transition is shifted towards higher Hubbard repulsions by
applying an electric field perpendicular to the slab. The spatial distribution
of site dependent quasiparticle weight shows that the quasiparticle weight is
maximum in few layers beneath the surface. Moreover only at higher Hubbard
repulsion, larger than the bulk critical U, the electric field will be totally
screened only for centeral cites. Our results show that by presence of an
electric field perpendicular to a thin film made of a strongly correlated
material, states near the surface will remain metallic while the bulk becomes
insulating after some critical U. In contrast, in the absence of the electric
field the surface becomes insulating before the bulk
Spin Fidelity for Three-qubit Greenberger-Horne-Zeilinger and W States Under Lorentz Transformations
Constructing the reduced density matrix for a system of three massive
spin particles described by a wave packet with Gaussian momentum
distribution and a spin part in the form of GHZ or W state, the fidelity for
the spin part of the system is investigated from the viewpoint of moving
observers in the jargon of special relativity. Using a numerical approach, it
turns out that by increasing the boost speed, the spin fidelity decreases and
reaches to a non-zero asymptotic value that depends on the momentum
distribution and the amount of momentum entanglement.Comment: 12pages, 2 figure
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