19,137 research outputs found
Suppression of dissipation in Nb thin films with triangular antidot arrays by random removal of pinning sites
The depinning current Ic versus applied magnetic field B close to the
transition temperature Tc of Nb thin films with randomly diluted triangular
arrays of antidots is investigated. % Our experiments confirm essential
features in Ic(B) as predicted by Reichhardt and Olson Reichhardt [Phys.Rev. B
76, 094512 (2007)]. % We show that, by introducing disorder into periodic
pinning arrays, Ic can be enhanced. % In particular, for arrays with fixed
density n_p of antidots, an increase in dilution Pd induces an increase in Ic
and decrease of the flux-flow voltage for B>Bp=n_p Phi_0.Comment: 5 pages, 4 figure
Behavioural clusters and predictors of performance during recovery from stroke
We examined the patterns and variability of recovery post-stroke in multiple behavioral domains. A large cohort of first time stroke patients with heterogeneous lesions was studied prospectively and longitudinally at 1-2 weeks, 3 months and one year post-injury with structural MRI to measure lesion anatomy and in-depth neuropsychological assessment. Impairment was described at all timepoints by a few clusters of correlated deficits. The time course and magnitude of recovery was similar across domains, with change scores largely proportional to the initial deficit and most recovery occurring within the first three months. Damage to specific white matter tracts produced poorer recovery over several domains: attention and superior longitudinal fasciculus II/III, language and posterior arcuate fasciculus, motor and corticospinal tract. Finally, after accounting for the severity of the initial deficit, language and visual memory recovery/outcome was worse with lower education, while the occurrence of multiple deficits negatively impacted attention recovery
Commensurability effects in superconducting Nb films with quasiperiodic pinning arrays
We study experimentally the critical depinning current Ic versus applied
magnetic field B in Nb thin films which contain 2D arrays of circular antidots
placed on the nodes of quasiperiodic (QP) fivefold Penrose lattices. Close to
the transition temperature Tc we observe matching of the vortex lattice with
the QP pinning array, confirming essential features in the Ic(B) patterns as
predicted by Misko et al. [Phys. Rev. Lett, vol.95, 177007 (2005)]. We find a
significant enhancement in Ic(B) for QP pinning arrays in comparison to Ic in
samples with randomly distributed antidots or no antidots.Comment: 4 pages, 3 figure
Variant supercurrent multiplets
In N = 1 rigid supersymmetric theories, there exist three standard
realizations of the supercurrent multiplet corresponding to the (i) old
minimal, (ii) new minimal and (iii) non-minimal off-shell formulations for N =
1 supergravity. Recently, Komargodski and Seiberg in arXiv:1002.2228 put
forward a new supercurrent and proved its consistency, although in the past it
was believed not to exist. In this paper, three new variant supercurrent
multiplets are proposed. Implications for supergravity-matter systems are
discussed.Comment: 11 pages; V2: minor changes in sect. 3; V3: published version; V4:
typos in eq. (2.3) corrected; V5: comments and references adde
Geometry-induced reduction of the critical current in superconducting nanowires
Reduction of the critical current in narrow superconducting NbN lines with
sharp and rounded bends with respect to the critical current in straight lines
was studied at different temperatures. We compare our experimental results with
the reduction expected in the framework of the London model and the
Ginsburg-Landau model. We have experimentally found that the reduction is
significantly less than either model predicts. We also show that in our NbN
lines the bends mostly contribute to the reduction of the critical current at
temperatures well below the superconducting transition temperature
Seeing motion and apparent motion
In apparent motion experiments, participants are presented with what is in fact a succession of two brief stationary stimuli at two different locations, but they report an impression of movement. Philosophers have recently debated whether apparent motion provides evidence in favour of a particular account of the nature of temporal experience. I argue that the existing discussion in this area is premised on a mistaken view of the phenomenology of apparent motion and, as a result, the space of possible philosophical positions has not yet been fully explored. In particular, I argue that the existence of apparent motion is compatible with an account of the nature of temporal experience that involves a version of direct realism. In doing so, I also argue against two other claims often made about apparent motion, viz. that apparent motion is the psychological phenomenon that underlies motion experience in the cinema, and that apparent motion is subjectively indistinguishable from real motion
- âŠ