Experimental demonstration of the mechanism of steady-state microbunching.

The use of particle accelerators as photon sources has enabled advances in science and technology. Currently the workhorses of such sources are storage-ring-based synchrotron radiation facilities and linear-accelerator-based free-electron lasers. Synchrotron radiation facilities deliver photons with high repetition rates but relatively low power, owing to their temporally incoherent nature.

Transverse resonance island buckets for synchrotron-radiation based electron time-of-flight spectroscopy.

At the Metrology Light Source (MLS), the compact electron storage ring of the Physikalisch-Technische Bundesanstalt (PTB) with a circumference of 48 m, a specific operation mode with two stable closed orbits for stored electrons was realized by transverse resonance island buckets. One of these orbits is closing only after three turns. In combination with single-bunch operation, the new mode was applied for electron time-of-flight spectroscopy with an interval of the synchrotron radiation pulses which is three times the revolution period at the MLS of 160 ns.

Enhancing the sensitivity of nano-FTIR spectroscopy.

Synchrotron radiation-based nano-FTIR spectroscopy utilizes the highly brilliant and ultra-broadband infrared (IR) radiation provided by electron storage rings for the infrared spectroscopic characterization of samples at the nanoscale. In order to exploit the full potential of this approach we investigated the influence of the properties of the radiation source, such as the electron bunch shape and spectral bandwidth of the emitted radiation, on near-field infrared spectra of silicon-carbide (SiC). The adapted configuration of the storage ring optics enables a modification of the transverse electron bunch profile allowing an increase of the measured near-field signal amplitude.

A model describing stable coherent synchrotron radiation in storage rings.

We present a model describing high power stable broadband coherent synchrotron radiation (CSR) in the terahertz frequency region in an electron storage ring. The model includes distortion of bunch shape from the synchrotron radiation (SR), which enhances higher frequency coherent emission, and limits to stable emission due to an instability excited by the SR wakefield. It gives a quantitative explanation of several features of the recent observations of CSR at the BESSY II storage ring.

Brilliant, coherent far-infrared (THz) synchrotron radiation.

A new technology for generating steady state, brilliant, broadband, coherent, far-infrared (FIR) radiation in electron storage rings is presented, suitable for FIR spectroscopy. An FIR power increase of up to 100 000 compared to the normal, incoherent synchrotron radiation in the range of approximately 5 to approximately 40 cm(-1) could be achieved. The source is up to 1000 times more brillant compared to a standard Hg arc lamp.

A constraint-based approach to modelling the mobility of the human knee joint.

A model of knee mobility able to predict the range and pattern of movement in the unloaded joint was proposed by Wilson et al. (J. Biomech.

Steady-state far-infrared coherent synchrotron radiation detected at BESSY II.

At BESSY II it is demonstrated that far-infrared coherent synchrotron radiation (CSR) can be generated by a controlled, steady-state process at storage rings. As an indication for coherent emission, the radiated power grows with the square of the beam current. The spectrum was analyzed by an interferometer in the 1-mm to 0.

In vitro evaluation of the resistance to dislocation of a meniscal-bearing total knee prosthesis between 30 degrees and 90 degrees of knee flexion.

An increased incidence of dislocation is the most important potential disadvantage introduced by the use of meniscal-bearing prostheses. The aim of this in vitro study was to measure the resistance to dislocation of a meniscal-bearing total knee arthroplasty in various circumstances and to establish which anatomic structures contribute to bearing stability. The prosthesis was implanted into cadaver knee specimens mounted in a 6 df rig.

The components of passive knee movement are coupled to flexion angle.

Movement of the unloaded knee has been described in several studies by an "envelope of passive flexion", a description that does not describe or explain the widely reported coupling of internal tibial rotation to flexion. The objective of the current study was to show that the envelope of passive knee flexion can be reduced to a coupled path. Two hypotheses were tested: (1) in normal knees flexed passively, internal/external rotation, abduction/adduction and all three components of translation are coupled to flexion angle, and (2) the tibia rotates internally as the knee is flexed passively.

Ligaments and articular contact guide passive knee flexion.

The aim of this study was to test the hypothesis that the coupled features of passive knee flexion are guided by articular contact and by the isometric fascicles of the ACL, PCL and MCL. A three-dimensional mathematical model of the knee was developed, in which the articular surfaces in the lateral and medial compartments and the isometric fascicles in the ACL, PCL and MCL were represented as five constraints in a one degree-of-freedom parallel spatial mechanism. Mechanism analysis techniques were used to predict the path of motion of the tibia relative to the femur.

Pericardioperitoneal shunt: an alternative treatment for malignant pericardial effusion.

The treatment of 37 consecutive cases of symptomatic malignant pericardial effusion over a period of 13 years was retrospectively analyzed. The most common diagnoses were lung cancer (59%) and breast cancer (11%). In the most recent 4 patients, the Denver pleuroperitoneal shunt was used to drain the pericardial effusion into the peritoneal cavity.