RESUMO
The motion of line defects (dislocations) has been studied for more than 60 years, but the maximum speed at which they can move is unresolved. Recent models and atomistic simulations predict the existence of a limiting velocity of dislocation motion between the transonic and subsonic ranges at which the self-energy of dislocation diverges, though they do not deny the possibility of the transonic dislocations. We used femtosecond x-ray radiography to track ultrafast dislocation motion in shock-compressed single-crystal diamond. By visualizing stacking faults extending faster than the slowest sound wave speed of diamond, we show the evidence of partial dislocations at their leading edge moving transonically. Understanding the upper limit of dislocation mobility in crystals is essential to accurately model, predict, and control the mechanical properties of materials under extreme conditions.
RESUMO
BACKGROUND: The analysis of the different operative reconstructions of patellar tendon ruptures has not been reported. A critical review of the existing literature was performed to identify the different operative techniques and the post-operative outcomes in acute, chronic and post-total knee arthroplasty (TKA) patellar tendon rupture repairs. METHODS: Using PRISMA guidelines, a review of the English-written literature published after 1947 was performed using the MEDLINE, PubMed and Cochrane libraries in November 2013 to retrieve case series with the keywords "Patellar tendon" AND "Rupture" AND "Repair" in their title or abstract. RESULTS: Forty-one manuscripts, reporting on 503 patients were analysed. Three-hundred-and-fifty-four acute repairs described eight different operative techniques. One-hundred-and-forty-nine chronic repairs described eight different operative techniques. Sixty-eight post-TKA repairs described nine different operative techniques. Six acute, four chronic and seven post-TKA repair operative techniques reported failures. In acute repair, using a primary repair method augmented with cerclage wire, Dall-Miles cable or non-absorbable sutures reported the best clinical results, with a 2% failure rate. Alternatively, for chronic and post-TKA repair, autogeneous grafts were significantly better than primary repair (p=0.0252, 0.0038 respectively). CONCLUSION: Acute surgical repair of a patellar tendon rupture using augmented primary repair is associated with the best post-operative outcomes. In chronic and post-TKA repair, autogeneous grafts produce best post-operative outcomes. Immediate post-operative mobilisation should be considered in all repairs. Future papers reporting on patellar operative repairs should have a standardised scoring method of functional outcome to allow more comprehensive comparison and evaluation.