44,679 research outputs found
Frequency-dependent ratchet effect in superconducting films with a tilted washboard pinning potential
The influence of an ac current of arbitrary amplitude and frequency on the
mixed-state dc-voltage-ac-drive ratchet response of a superconducting film with
a dc current-tilted uniaxial cosine pinning potential at finite temperature is
theoretically investigated. The results are obtained in the single-vortex
approximation, i.e., for non-interacting vortices, within the frame of an exact
solution of the appropriate Langevin equation in terms of a matrix continued
fraction. Formulas for the dc voltage ratchet response and absorbed power in ac
response are discussed as functions of ac current amplitude and frequency as
well as dc current induced tilt in a wide range of corresponding dimensionless
parameters. Special attention is paid to the physical interpretation of the
obtained results in adiabatic and high-frequency ratchet responses taking into
account both running and localized states of the (ac+dc)-driven vortex motion
in a washboard pinning potential. Our theoretical results are discussed in
comparison with recent experimental work on the high-frequency ratchet response
in nanostructured superconducting films [B. B. Jin et al., Phys. Rev. B 81
(2010) 174505].Comment: 13 pages, 11 figure
Z boson production in proton-lead collisions at the LHC accounting for transverse momenta of initial partons
We perform a calculation of inclusive boson production in proton-lead
collisions at the LHC taking into account the transverse momenta of the initial
partons. We use the framework of -factorization combining transverse
momentum dependent parton distributions (TMDs) with off-shell matrix elements.
In order to do it we need to construct appropriate TMDs for lead nuclei which
is done using the parton branching method. Our computations are compared with
data from CMS taken at TeV. The results are in good agreement
with the measurements especially the transverse momentum distribution of the
boson.Comment: 17 pages, 12 figure
Calculation of the Z+jet cross section including transverse momenta of initial partons
We perform calculations of Z+jet cross-section taking into account the
transverse momenta of the initial partons. Transverse Momentum Dependent (TMD)
parton densities obtained with the Parton Branching method are used and higher
order corrections are included via TMD parton showers in the initial state. The
predictions are compared to measurements of forward Z+jet production of the
LHCb collaboration at TeV. We show that the results obtained in
kT-factorization are in good agreement with results obtained from a NLO
calculation matched with traditional parton showers. We also demonstrate that
in the forward rapidity region, kT-factorization and hybrid factorization
predictions agree with each other.Comment: 16 pages, 8 figure
New Candidates for Topological Insulators : Pb-based chalcogenide series
Here, we theoretically predict that the series of Pb-based layered
chalcogenides, PbBiSe and PbSbTe, are possible
new candidates for topological insulators. As increases, the phase
transition from a topological insulator to a band insulator is found to occur
between and 3 for both series. Significantly, among the new topological
insulators, we found a bulk band gap of 0.40eV in PbBiSe which is one
of the largest gap topological insulators, and that PbSbTe is
located in the immediate vicinity of the topological phase boundary, making its
topological phase easily tunable by changing external parameters such as
lattice constants. Due to the three-dimensional Dirac cone at the phase
boundary, massless Dirac fermions also may be easily accessible in
PbSbTe
Refugees, trauma and adversity-activated development
The nature of the refugee phenomenon is examined and the position of mental health professionals is located in relation to it. The various uses of the word 'trauma' are explored and its application to the refugee context is examined. It is proposed that refugees' response to adversity is not limited to being traumatized but includes resilience and Adversity-Activated Development (AAD). Particular emphasis is given to the distinction between resilience and AAD. The usefulness of the 'Trauma Grid' in the therapeutic process with refugees is also discussed. The Trauma Grid avoids global impressions and enables a more comprehensive and systematic way of identifying the individual refugee's functioning in the context of different levels, i.e. individual, family, community and society/culture. Finally, I discuss implications for therapeutic work with refugees
NRG for the bosonic single-impurity Anderson model: Dynamics
The bosonic single-impurity Anderson model (B-SIAM) is studied to understand
the local dynamics of an atomic quantum dot (AQD) coupled to a Bose-Einstein
condensation (BEC) state, which can be implemented to probe the entanglement
and the decoherence of a macroscopic condensate. Our recent approach of the
numerical renormalization group (NRG) calculation for the B-SIAM revealed a
zero-temperature phase diagram, where a Mott phase with local depletion of
normal particles is separated from a BEC phase with enhanced density of the
condensate. As an extension of the previous work, we present the calculations
of the local dynamical quantities of the B-SIAM which reinforce our
understanding of the physics in the Mott and the BEC phases.Comment: 12 pages, 13 figure
Characteristics of Feedback that Influence Student Confidence and Performance during Mathematical Modeling
This study focuses on characteristics of written feedback that influence studentsâ performance and confidence in addressing the mathematical complexity embedded in a Model-Eliciting Activity (MEA). MEAs are authentic mathematical modeling problems that facilitate studentsâ iterative development of solutions in a realistic context. We analyzed 132 first-year engineering studentsâ confidence levels and mathematical model scores on aMEA(pre and post feedback), along with teaching assistant feedback given to the students. The findings show several examples of affective and cognitive feedback that students reported that they used to revise their models. Studentsâ performance and confidence in developing mathematical models can be increased when they are in an environment where they iteratively develop models based on effective feedback
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