21,692 research outputs found
A phenomenological analysis of azimuthal asymmetries in unpolarized semi-inclusive deep inelastic scattering
We present a phenomenological analysis of the cos-phi and cos-2phi
asymmetries in unpolarized semi-inclusive deep inelastic scattering, based on
the recent multidimensional data released by the COMPASS and HERMES
Collaborations. In the TMD framework, valid at relatively low transverse
momenta, these asymmetries arise from intrinsic transverse momentum and
transverse spin effects, and from their correlations. The role of the Cahn and
Boer-Mulders effects in both azimuthal moments is explored up to order 1/Q. As
the kinematics of the present experiments is dominated by the low-Q^2 region,
higher-twist contributions turn out to be important, affecting the results of
our fits.Comment: 18 pages, 5 figures, one paragraph added at the end of Section IV,
one reference added. PRD versio
Low-temperature transport through a quantum dot between two superconductor leads
We consider a quantum dot coupled to two BCS superconductors with same gap
energies . The transport properties are investigated by means of
infinite- noncrossing approximation. In equilibrium density of states, Kondo
effect shows up as two sharp peaks around the gap bounds. Application of a
finite voltage bias leads these peaks to split, leaving suppressed peaks near
the edges of energy gap of each lead. The clearest signatures of the Kondo
effect in transport are three peaks in the nonlinear differential conductance:
one around zero bias, another two at biases . This result is
consistent with recent experiment. We also predict that with decreasing
temperature, the differential conductances at biases anomalously
increase, while the linear conductance descends.Comment: replaced with revised versio
Dispersionless motion in a driven periodic potential
Recently, dispersionless (coherent) motion of (noninteracting) massive
Brownian particles, at intermediate time scales, was reported in a sinusoidal
potential with a constant tilt. The coherent motion persists for a finite
length of time before the motion becomes diffusive. We show that such coherent
motion can be obtained repeatedly by applying an external zero-mean square-wave
drive of appropriate period and amplitude, instead of a constant tilt. Thus,
the cumulative duration of coherent motion of particles is prolonged. Moreover,
by taking an appropriate combination of periods of the external field, one can
postpone the beginning of the coherent motion and can even have coherent motion
at a lower value of position dispersion than in the constant tilt case.Comment: 4 pages, 4 figure
Noise rectification by a superconducting loop with two weak links
We consider a superconducting loop with two weak links that encloses a
magnetic flux. The weak links are unequal and are treated as Josephson
junctions with non-sinusoidal phase dependence. We devise a model that takes
into account the fluctuation of the critical currents, due to the fluctuations
of the order parameter in the weak links. These fluctuations are important near
the onset of superconductivity; in this regime they may significantly weaken
and eventually disconnect the superconducting loop. As a consequence of these
fluctuations and of the resistive noise in the junctions, the average dc
voltage does not vanish. Our model can be easily extended to provide a
qualitative description of a recent experiment.Comment: version accepted by PR
Spin analog of the controlled Josephson charge current
We propose a controlled Josephson spin current across the junction of two
non-centrosymmetric superconductors like CePt_3Si. The Josephson spin current
arises due to direction dependent tunneling matrix element and different
momentum dependent phases of the triplet components of the gap function. Its
modulation with the angle \xi between the noncentrosymmetric axes of two
superconductors is proportional to \sin \xi. This particular dependence on \xi
may find application of the proposed set-up in making a Josephson spin switch.Comment: 4 pages, 1 figure; title is changed; article is rewritte
Increasing empathic accuracy through practice and feedback in a clinical interviewing course
Accurate empathy, long argued to be important in psychotherapy, now is an object of social-cognitive research. Graduate-level psychology students viewed brief portions of a therapy session and inferred the thoughts and feelings of the client. Accuracy scores were the rated similarity of their inferences to the client\u27s reported thoughts and feelings. Throughout the semester course in interviewing, experimental participants practiced such judgments with feedback, while controls did not. Both groups\u27 accuracy increased from pre-to post-test on inferred feelings, in part because the post-test was easier. Nonetheless experimental participants on the post-test had greater accuracy of inferred feelings than controls. Women were more accurate than men in inferences for thoughts at post-test. Implications for training and future research are discussed
Running-phase state in a Josephson washboard potential
We investigate the dynamics of the phase variable of an ideal underdamped
Josephson junction in switching current experiments. These experiments have
provided the first evidence for macroscopic quantum tunneling in large
Josephson junctions and are currently used for state read-out of
superconducting qubits. We calculate the shape of the resulting macroscopic
wavepacket and find that the propagation of the wavepacket long enough after a
switching event leads to an average voltage increasing linearly with time.Comment: 6 pages, 3 figure
Statistics of voltage fluctuations in resistively shunted Josephson junctions
The intrinsic nonlinearity of Josephson junctions converts Gaussian current
noise in the input into non-Gaussian voltage noise in the output. For a
resistively shunted Josephson junction with white input noise we determine
numerically exactly the properties of the few lowest cumulants of the voltage
fluctuations, and we derive analytical expressions for these cumulants in
several important limits. The statistics of the voltage fluctuations is found
to be Gaussian at bias currents well above the Josephson critical current, but
Poissonian at currents below the critical value. In the transition region close
to the critical current the higher-order cumulants oscillate and the voltage
noise is strongly non-Gaussian. For coloured input noise we determine the third
cumulant of the voltage.Comment: 9 pages, 5 figure
Designing arrays of Josephson junctions for specific static responses
We consider the inverse problem of designing an array of superconducting
Josephson junctions that has a given maximum static current pattern as function
of the applied magnetic field. Such devices are used for magnetometry and as
Terahertz oscillators. The model is a 2D semilinear elliptic operator with
Neuman boundary conditions so the direct problem is difficult to solve because
of the multiplicity of solutions. For an array of small junctions in a passive
region, the model can be reduced to a 1D linear partial differential equation
with Dirac distribution sine nonlinearities. For small junctions and a
symmetric device, the maximum current is the absolute value of a cosine Fourier
series whose coefficients (resp. frequencies) are proportional to the areas
(resp. the positions) of the junctions. The inverse problem is solved by
inverse cosine Fourier transform after choosing the area of the central
junction. We show several examples using combinations of simple three junction
circuits. These new devices could then be tailored to meet specific
applications.Comment: The article was submitted to Inverse Problem
Water governance in France: institutional framework, stakeholders, arrangements and process
The enforcement of the European Water Framework Directive (WFD) is not such an administrative issue in France as it is in other countries, since competent authorities (water agencies) already have jurisdiction over major watersheds (districts). As far as the WFD implementation is concerned, setting and reaching objectives of water quality (good status) and implementing cost recovery policy are more challenging for France and will require necessary changes and adjustments. Water in France is not managed according to its ownership, but its uses. In this chapter, after (i) an overview of the water governance institutional framework, (ii) the water governance arrangements is tackled: the main stakeholders is described and key issues of the current process of making decision are dealt with, in the general context of implementing the WFD. The original institutional tools developed to integrate different water uses for the sake of ecosystems preservation are also considered
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