2,717 research outputs found
Transverse rectification of disorder-induced fluctuations in a driven system
We study numerically the overdamped motion of particles driven in a two
dimensional ratchet potential. In the proposed design, of the so-called
geometrical-ratchet type, the mean velocity of a single particle in response to
a constant force has a transverse component that can be induced by the presence
of thermal or other unbiased fluctuations. We find that additional quenched
disorder can strongly enhance the transverse drift at low temperatures, in
spite of reducing the transverse mobility. We show that, under general
conditions, the rectified transverse velocity of a driven particle fluid is
equivalent to the response of a one dimensional flashing ratchet working at a
drive-dependent effective temperature, defined through generalized Einstein
relations.Comment: 4.5 pages, 3 fig
Effect of time delay on feedback control of a flashing ratchet
It was recently shown that the use of feedback control can improve the
performance of a flashing ratchet. We investigate the effect of a time delay in
the implementation of feedback control in a closed-loop collective flashing
ratchet, using Langevin dynamics simulations. Surprisingly, for a large
ensemble, a well-chosen delay time improves the ratchet performance by allowing
the system to synchronize into a quasi-periodic stable mode of oscillation that
reproduces the optimal average velocity for a periodically flashing ratchet.
For a small ensemble, on the other hand, finite delay times significantly
reduce the benefit of feedback control for the time-averaged velocity, because
the relevance of information decays on a time scale set by the diffusion time
of the particles. Based on these results, we establish that experimental use of
feedback control is realistic.Comment: 6 pages, 6 figures, to appear in Europhysics Letter
Symmetry of two terminal, non-linear electric conduction
The well-established symmetry relations for linear transport phenomena can
not, in general, be applied in the non-linear regime. Here we propose a set of
symmetry relations with respect to bias voltage and magnetic field for the
non-linear conductance of two-terminal electric conductors. We experimentally
confirm these relations using phase-coherent, semiconductor quantum dots.Comment: 4 pages, 4 figure
Phase Ordering Dynamics of Theory with Hamiltonian Equations of Motion
Phase ordering dynamics of the (2+1)- and (3+1)-dimensional theory
with Hamiltonian equations of motion is investigated numerically. Dynamic
scaling is confirmed. The dynamic exponent is different from that of the
Ising model with dynamics of model A, while the exponent is the same.Comment: to appear in Int. J. Mod. Phys.
Screening of a HUVEC cDNA library with transplant-associated coronary artery disease sera identifies RPL7 as a candidate autoantigen associated with this disease.
A HUVEC cDNA library was screened with sera from two patients who had developed transplant-associated coronary artery disease (TxCAD) following cardiac transplantation. A total of six positive clones were isolated from a primary screen of 40 000 genes. Subsequent DNA sequence analysis identified these to be lysyl tRNA synthetase, ribosomal protein L7, ribosomal protein L9, beta transducin and TANK. Another gene whose product could not be identified showed homology to a human cDNA clone (DKFZp566M063) derived from fetal kidney. Full-length constructs of selected genes were expressed as his-tag recombinant fusion proteins and used to screen a wider patient base by ELISA to determine prevalence and association with TxCAD. Of these ribosomal protein L7 showed the highest prevalence (55.6%) with TxCAD sera compared to 10% non-CAD
A microfabricated ion trap with integrated microwave circuitry
We describe the design, fabrication and testing of a surface-electrode ion
trap, which incorporates microwave waveguides, resonators and coupling elements
for the manipulation of trapped ion qubits using near-field microwaves. The
trap is optimised to give a large microwave field gradient to allow
state-dependent manipulation of the ions' motional degrees of freedom, the key
to multiqubit entanglement. The microwave field near the centre of the trap is
characterised by driving hyperfine transitions in a single laser-cooled 43Ca+
ion.Comment: 4 pages, 5 figure
Araracuara, un nuevo género de Rhamnaceae de la Amazonía colombiana
Se describe e ilustra Araracuara Fern. Alonso, un nuevo género de
la familia Rhamnaceae conocido tan sólo de las mesetas de arenisca
de la Amazonía colombiana. Se discuten sus posibles afinidades en
la familia y se sugiere que estaríamos ante un género relíctico, relacionado
con el pantropical Colubrina y en menor medida con el
amazónico Ampelozizyphus. Se incluye una clave para los géneros
de Rhamnaceae de Colombia y un apéndice con una muestra representativa
de especies de los géneros estudiados, algunos de ellos
pobremente documentados de territorio colombiano.Peer reviewe
Improving the Socio-emotional Well-being of the Older Generation through the Implementation of Territorial Marketing
This article is based on the analysis of the possibility of using Berkman's conceptual model of mechanism of social networks influence on human health to improve the well-being of the older generation in Russia. The emphasis is put on the development of social contacts of older people through the implementation of territorial marketing. Objective and subjective indicators of well-being of older people are directly related to the characteristics and peculiarities of the territory where they live and carry out their activities (city, region, country). In this context, marketing of territory can be regarded as an activity aimed at creating and maintaining comfortable living conditions of different age groups, taking into considerations their characteristics. Special attention is paid to the social and emotional mechanisms of social support, social influence, social inclusion, social participation, interpersonal contacts and access to resources and benefits the territory of older generation. Specificity of older adults segmentation of the region (the city) is defined. The importance of active cooperation of various age groups identified in the process of territorial segmentation of the market is particularly stressed, in terms of improving the lives of older adults
Voltage rectification effects in mesoscopic superconducting triangles: experiment and modelling
The interaction of externally applied currents with persistent currents
induced by magnetic field in a mesoscopic triangle is investigated. As a
consequence of the superposition of these currents, clear voltage rectification
effects are observed. We demonstrate that the amplitude of the rectified signal
strongly depends on the configurations of the current leads with the lowest
signal obtained when the contacts are aligned along a median of the triangle.
When the contacts are aligned off-centered compared to the geometrical center,
the voltage response shows oscillations as a function of the applied field,
whose sign can be controlled by shifting the contacts. These results are in
full agreement with theoretical predictions for an analogous system consisting
of a closed loop with a finite number of identical Josephson junctions.Comment: 5 pages, 4 figures, published in Phys. Rev.
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