Energy relaxation in graphene and its measurement with supercurrent

We study inelastic energy relaxation in graphene for low energies to find out how electrons scatter with acoustic phonons and other electrons. By coupling the graphene to superconductors, we create a strong dependence of the measured signal, i.e.,\ critical Josephson current, on the electron population on different energy states. Since the relative population of high- and low-energy states is determined by the inelastic scattering processes, the critical current becomes an effective probe for their strength. We argue that the electron-electron interaction is the dominant relaxation method and, in our model of two-dimensional electron-electron scattering, we find a scattering time $\tau_{e-e}=5... 13$ ps at T=500 mK, 1-2 orders of magnitude smaller than predicted by theory.Comment: 10 pages, 13 figures submitted to Physical Review

Reliability and Validity of The Finnish Version of The Boston Carpal Tunnel Questionnaire among Surgically Treated Carpal Tunnel Syndrome Patients

Background and Aims: The Boston Carpal Tunnel Questionnaire is the most commonly used outcome measure in the assessment of carpal tunnel syndrome. The purpose of this study was to translate the original Boston Carpal Tunnel Questionnaire into Finnish and validate its psychometric properties. Materials and Methods: We translated and culturally adapted the Boston Carpal Tunnel Questionnaire into Finnish. Subsequently, 193 patients completed the Finnish version of the Boston Carpal Tunnel Questionnaire, 6-Item CTS Symptoms Scale, and EuroQol 5 Dimensions 12 months after carpal tunnel release. The Boston Carpal Tunnel Questionnaire was re-administered after a 2-week interval. We calculated construct validity, internal consistency, test-retest reliability, and coefficient of repeatability. We also examined floor and ceiling effects. Results: The cross-cultural adaptation required only minor modifications to the questions. Both subscales of the Boston Carpal Tunnel Questionnaire (Symptom Severity Scale and Functional Status Scale) correlated significantly with the CTS-6 and EuroQol 5 Dimensions, indicating good construct validity. The Cronbach's alpha was 0.93 for both the Symptom Severity Scale and Functional Status Scale, indicating high internal consistency. Test-retest reliability was excellent, with an intraclass correlation coefficient greater than 0.8 for both scales. The coefficient of repeatability was 0.80 for the Symptom Severity Scale and 0.68 for the Functional Status Scale. We observed a floor effect in the Functional Status Scale in 28% of participants. Conclusion: Our study shows that the present Finnish version of the Boston Carpal Tunnel Questionnaire is reliable and valid for the evaluation of symptom severity and functional status among surgically treated carpal tunnel syndrome patients. However, owing to the floor effect, the Functional Status Score may have limited ability to detect differences in patients with good post-operative outcomes.Peer reviewe

Temperature dependence of surface reconstructions of Au on Pd(110)

Surface reconstructions of Au film on Pd(110) substrate are studied using a local Einstein approximation to quasiharmonic theory with the Sutton-Chen interatomic potential. Temperature dependent surface free energies for different coverages and surface structures are calculated. Experimentally observed transformations from $(1\times1)$ to $(1 \times 2)$ and $(1 \times 3)$ structures can be explained in the framework of this model. Also conditions for Stranski-Krastanov growth mode are found to comply with experiments. The domain of validity of the model neglecting mixing entropy is analyzed.Comment: 7 pages, REVTeX two-column format, 3 postscript figures available on request from [email protected] To appear in Phys. Rev. Letter

Assessment of the structural validity of three foot and ankle specific patient-reported outcome measures

Background: The structural validity of the Lower extremity functional scale (LEFS), the Visual analogue scale foot and ankle (VAS-FA), and the Western Ontario and McMaster Universities osteoarthritis index (WOMAC) has not been compared earlier in patients after foot and ankle surgery. Methods: Altogether 165 previously operated patients completed the foot and ankle specific instruments, the 15D health-related quality of life (HRQoL) instrument, and general health (VAS). Results: The LEFS, the VAS-FA and the WOMAC had slight differences in their measurement properties. The VAS-FA had the best targeting and coverage. All three foot and ankle measures accounted for mobility and usual activities when compared to the different aspects of generic HRQoL. Conclusions: The LEFS, the VAS-FA and the WOMAC have relatively similar psychometric properties among foot and ankle patients, yet the VAS-FA provides the best targeting and coverage. (C) 2019 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.Peer reviewe

Photoelectron spectra of aluminum cluster anions: Temperature effects and ab initio simulations

Photoelectron (PES) spectra from aluminum cluster anions (from 12 to 15 atoms) at various temperature regimes, were studied using ab-initio molecular dynamics simulations and experimentally. The calculated PES spectra, obtained via shifting of the simulated electronic densities of states by the self-consistently determined values of the asymptotic exchange-correlation potential, agree well with the measured ones, allowing reliable structural assignments and theoretical estimation of the clusters' temperatures.Comment: RevTex, 3 gif figures. Scheduled for Oct 15, 1999, issue of Phys. Rev. B as Rapid Communicatio

Diffusion processes and growth on stepped metal surfaces

We study the dynamics of adatoms in a model of vicinal (11m) fcc metal surfaces. We examine the role of different diffusion mechanisms and their implications to surface growth. In particular, we study the effect of steps and kinks on adatom dynamics. We show that the existence of kinks is crucially important for adatom motion along and across steps. Our results are in agreement with recent experiments on Cu(100) and Cu(1,1,19) surfaces. The results also suggest that for some metals exotic diffusion mechanisms may be important for mass transport across the steps.Comment: 3 pages, revtex, complete file available from ftp://rock.helsinki.fi/pub/preprints/tft/ or at http://www.physics.helsinki.fi/tft/tft_preprints.html (to appear in Phys. Rev. B Rapid Comm.

Common Origin for Surface Reconstruction and the Formation of Chains of Metal Atoms

During the fracture of nanocontacts gold spontaneously forms freely suspended chains of atoms, which is not observed for the iso-electronic noble metals Ag and Cu. Au also differs from Ag and Cu in forming reconstructions at its low-index surfaces. Using mechanically controllable break junctions we show that all the 5d metals that show similar reconstructions (Ir, Pt and Au) also form chains of atoms, while both properties are absent in the 4d neighbor elements (Rh, Pd, Ag), indicating a common origin for these two phenomena. A competition between s and d bonding is proposed as an explanation

Enhanced user performance in an image gallery application with a mobile autostereoscopic touch display

In this study, we explored how stereoscopic depth affects performance and user experience in a mobile device with an autostereoscopic touch display. Participants conducted a visual search task with an image gallery application on three layouts with different depth ranges. The task completion times were recorded, and the participants were asked to rate their experiences. The results revealed that the image search times were facilitated by a mild depth effect and that too great a depth slowed search times and decreased user-experience ratings. © 2014 Elsevier B.V. All rights reserved

Spectroscopy with random and displaced random ensembles

Due to the time reversal invariance of the angular momentum operator J^2, the average energies and variances at fixed J for random two-body Hamiltonians exhibit odd-even-J staggering, that may be especially strong for J=0. It is shown that upon ensemble averaging over random runs, this behaviour is reflected in the yrast states. Displaced (attractive) random ensembles lead to rotational spectra with strongly enhanced BE2 transitions for a certain class of model spaces. It is explained how to generalize these results to other forms of collectivity.Comment: 4 pages, 4 figure

Origin of anomalously long interatomic distances in suspended gold chains

The discovery of long bonds in gold atom chains has represented a challenge for physical interpretation. In fact, interatomic distances frequently attain 3.0-3.6 A values and, distances as large as 5.0 A may be seldom observed. Here, we studied gold chains by transmission electron microscopy and performed theoretical calculations using cluster ab initio density functional formalism. We show that the insertion of two carbon atoms is required to account for the longest bonds, while distances above 3 A may be due to a mixture of clean and one C atom contaminated bonds.Comment: 4 pages, 4 Postscript figures, to be published in Physical Review Letter