Surgical treatment of aspergillus spondylodiscitis.

Four cases of aspergillus spondylodiscitis were treated with operative debridement and fusion. In this rarely encountered mycotic infection of the spine in immunocompromised patients rapid destruction of the intervertebral disc and vertebral bodies can occur. In advanced cases antimycotic drug therapy is thought to be ineffective and a forcing indication for surgery exists when the destruction is progressive and spinal cord compression is imminent or manifest. Spinal instrumentation can be of help in maintaining or restoring spinal stability and maintaining spinal alignment. In our four patients the aspergillus spondylodiscitis was successfully eradicated and fusion achieved. In two of three patients with a neurologic deficit, this deficit disappeared. Two patients died within 6 months after the operative treatment, due to complications related to the underlying illness. One patient was left with a subtotal paraplegia.

Long-term results of rib perichondrial grafts for repair of cartilage defects in the human knee.

Eighty-eight patients with articular cartilage defects in the knee were treated by perichondrial arthroplasty between 1986 and 1992. An autogenous strip of costal perichondrium was fixed in place with fibrin glue, followed by immobilisation, continuous passive motion, and partial weightbearing. The results were evaluated using the Hospital for Special Surgery Score for knee function, radiographs, arthroscopy and the patient's subjective opinion. The results after a mean follow-up of 52 months were good in 38%, fair in 8% and poor in 55%. Previous drilling or shaving of a defect, concomitant osteoarthritis, older age and a long history of complaints proved to be contraindications. Good results were seen in 91% of isolated defects. Perichondrial arthroplasty can be beneficial in the repair of cartilage defects. It will reduce symptoms in carefully selected cases, and avoid more extensive operations for osteoarthritis.

Overcoming perspective elongation effects in laser-guide-star-aided adaptive optics.

Tracking the instantaneous position of the laser guide star removes its perspective elongation thus allowing an increased separation of the laser transmitter from its telescope.

Differential adaptive optics for astronomical interferometry.

Sometimes it suffices to make the wave-front distortions across individual telescopes equal rather than zero. This leads to the concept of differential adaptive optics.

Observing the sun with a fully tunable Lyot-Ohman filter.

We describe the properties of the Zeiss Universal Birefringent Filter and its optical and electronic interface with the Sacramento Peak Observatory'' vacuum telescope. The instrument permits observations of solar intensities, velocities, and/or magnetic fields in rapid succession in any Fraunhofer line in the 410-700-nm wavelength region with high spectral (0.004-0.013 nm) and high spatial (~1/3 sec of arc) resolution.

Narrow band filters based on magnetooptical effects.

The theory is developed for two types of narrow band filters. One is based on the Zeeman splitting of the line absorption coefficient; the other is based on the splitting of the anomalous dispersion curves in a Zeeman multiplet. The latter type filter is very similar to the Lyot-Ohman filter. It uses however the Macaluso Corbino effect instead of the linear birefringence of crystals. It is capable of giving very much narrower transmission profiles than the Lyot-Ohman filter and it has a very wide field.

A photoelectric focus and seeing monitor for solar telescopes.

A solar focus and seeing monitor is described which utilizes the properties of an image of the telescope objective formed after putting a knife edge next to the solar limb. In a very simple way simultaneous measurements are obtained for the telescope focus and for the image motion and blurring produced by the earth's atmosphere.