Extreme Domain Wall Speeds under Ultrafast Optical Excitation.

Time-resolved ultrafast EUV magnetic scattering was used to test a recent prediction of >10 km/s domain wall speeds by optically exciting a magnetic sample with a nanoscale labyrinthine domain pattern. Ultrafast distortion of the diffraction pattern was observed at markedly different timescales compared to the magnetization quenching. The diffraction pattern distortion shows a threshold dependence with laser fluence, not seen for magnetization quenching, consistent with a picture of domain wall motion with pinning sites. Supported by simulations, we show that a speed of ≈66 km/s for highly curved domain walls can explain the experimental data. While our data agree with the prediction of extreme, nonequilibrium wall speeds locally, it differs from the details of the theory, suggesting that additional mechanisms are required to fully understand these effects.

Clinical Implications of a One-hand Versus Two-hand Technique in the Silfverskiöld Test for Gastrocnemius Equinus.

Introduction Isolated gastrocnemius equinus contracture has been associated with several foot and ankle pathologies within the literature. The Silfverskiöld test is commonly used to identify isolated gastrocnemius contracture, however, the proper technique for performing the test has been scrutinized. The purpose of this study was to determine if there is a clinical significance in the ankle dorsiflexion that is obtained when the examination is performed incorrectly with a single hand versus the correct two-hand technique. Methods Thirty consecutive new patients with conditions associated with gastrocnemius equinus were included in the study. The Silfverskiöld test was performed with a two-hand technique and a single-hand technique. The amount of dorsiflexion obtained with the knee in full extension was measured and recorded using an extendable goniometer for each technique, with the arms aligned with the fifth metatarsal and fibular head. Results The average amount of dorsiflexion that was obtained with the two-hand technique with the knee in full extension was 76.3°±4.2°. When the one-hand technique was utilized the average amount of dorsiflexion obtained with the knee in full extension was 88.4°±4.2°. This was found to be statistically significant (p<0.01). Conclusion This study demonstrates that if the Silfverskiöld test is not performed correctly, the diagnosis of an isolated gastrocnemius contracture could be underappreciated. Accordingly, it may be important to perform the test with two hands in order to neutralize the hindfoot, midfoot, and forefoot, so that the dorsiflexion motion is through the tibiotalar joint alone.

Establishing the reliability and concurrent validity of physical performance tests using virtual reality equipment for community-dwelling healthy elders.

PURPOSE: The aim of this study was to determine the reliability and concurrent validity of commonly used physical performance tests using the OmniVR Virtual Rehabilitation System for healthy community-dwelling elders. METHOD: Participants (N = 40) were recruited by the authors and were screened for eligibility. The initial method of measurement was randomized to either virtual reality (VR) or clinically based measures (CM). Physical performance tests included the five times sit to stand, Timed Up and Go (TUG), Forward Functional Reach (FFR) and 30-s stand test. A random number generator determined the testing order. The test-re-test reliability for the VR and CM was determined. Furthermore, concurrent validity was determined using a Pearson product moment correlation (Pearson r). RESULTS: The VR demonstrated excellent reliability for 5 × STS intraclass correlation coefficient (ICC) = 0.931(3,1), FFR ICC = 0.846(3,1) and the TUG ICC = 0.944(3,1). The concurrent validity data for the VR and CM (ICC 3, k) were moderate for FFR ICC = 0.682, excellent 5 × STS ICC = 0.889 and excellent for the TUG ICC = 0.878. The concurrent validity of the 30-s stand test was good ICC = 0.735(3,1). CONCLUSIONS: This study supports the use of VR equipment for measuring physical performance tests in the clinic for healthy community-dwelling elders. IMPLICATIONS FOR REHABILITATION: Virtual reality equipment is not only used to treat balance impairments but it is also used to measure and determine physical impairments through the use of physical performance tests. Virtual reality equipment is a reliable and valid tool for collecting physical performance data for the 5 × STS, FFR, TUG and 30-s stand test for healthy community-dwelling elders.