No abstract

Extreme-ultraviolet to x-ray free-electron lasers (FELs) in operation for scientific applications are up to now single-user facilities. While most FELs generate around 100 photon pulses per second, FLASH at DESY can deliver almost two orders of magnitude more pulses in this time span due to its superconducting accelerator technology. This makes the facility a prime candidate to realize the next step in FELs-dividing the electron pulse trains into several FEL lines and delivering photon pulses to several users at the same time. Hence, FLASH has been extended with a second undulator line and self-amplified spontaneous emission (SASE) is demonstrated in both FELs simultaneously. FLASH can now deliver MHz pulse trains to two user experiments in parallel with individually selected photon beam characteristics. First results of the capabilities of this extension are shown with emphasis on independent variation of wavelength, repetition rate, and photon pulse length.

A search for a supersymmetric partner of the top quark (t 1 ) has been performed by the OPAL experiment i n e + e collisions at LEP. The integrated luminosity of the data sample analysed was 69.1 pb 1 , which corresponds to 1.6810 6 produced Z 0 ! q q e v ents. Not 1 candidates have been found. This study excludes the existence of thet 1 with a mass below 45.1 GeV at 95% C.L., where the mixing angle of left-and right-handed partners is smaller than 0.85 rad or greater than 1.15 rad, and the mass dierence between thet 1 and the lightest neutralino is greater than 5 GeV.

The purpose of this anatomical study was to explore the morphological variations of the semitendinosus and gracilis tendons in length and cross-section and the statistical relationship between length, cross-section, and body height. We studied the legs of 93 humans in 136 cadavers. In 43 specimens (46.2%) it was possible to harvest the tendons from both legs. We found considerable differences in the length and cross-section of the semitendinosus and the gracilis tendons with a significant correlation between the two. A correlation between the length of the femur, reflecting height, and the length of the tendons was only observed in specimens harvested from women. The reason for this gender difference was unclear. Additionally, there was a correlation between the cross-sectional area of the tendons and the length of the femur. Surgeons should be aware of the possibility of encountering insufficient length of tendon when undertaking reconstructive surgery as a result of anatomical variations between patients.

Background: Posterolateral tibial plateau shear fractures often require buttress plating, which can be performed through a posterolateral approach. The purpose of this study was to provide accurate data about the inferior limit of dissection.Methods: Forty unpaired cadaver adult lower limbs were used. The anterior tibial artery was identified because it coursed through the interosseous membrane. The perpendicular distance from the lateral joint line and fibula head to this landmark was measured.Results: The anterior tibial artery coursed through the interosseous membrane at 46.3 6 9.0 mm (range 27-62 mm) distal to the lateral tibial plateau and 35.7 6 9.0 mm (range 17-50 mm) distal to the fibula head.Conclusions: Displaced posterolateral tibial plateau fractures require anatomic reduction and stabilization with a buttress plate. This can be achieved by gaining access to the posterolateral tibial cortex. The distal limit of this dissection can be as little as 27 mm distal to the lateral tibial plateau. Dissection in this region should be carried out with caution.