Comet-like mineralogy of olivine crystals in an extrasolar proto-Kuiper belt.

Some planetary systems harbour debris disks containing planetesimals such as asteroids and comets. Collisions between such bodies produce small dust particles, the spectral features of which reveal their composition and, hence, that of their parent bodies. A measurement of the composition of olivine crystals (Mg(2-2x)Fe(2x)SiO(4)) has been done for the protoplanetary disk HD 100546 (refs 3, 4) and for olivine crystals in the warm inner parts of planetary systems. The latter compares well with the iron-rich olivine in asteroids (x ≈ 0.29). In the cold outskirts of the ß Pictoris system, an analogue to the young Solar System, olivine crystals were detected but their composition remained undetermined, leaving unknown how the composition of the bulk of Solar System cometary olivine grains compares with that of extrasolar comets. Here we report the detection of the 69-micrometre-wavelength band of olivine crystals in the spectrum of ß Pictoris. Because the disk is optically thin, we can associate the crystals with an extrasolar proto-Kuiper belt a distance of 15-45 astronomical units from the star (one astronomical unit is the Sun-Earth distance), determine their magnesium-rich composition (x = 0.01 ± 0.001) and show that they make up 3.6 ± 1.0 per cent of the total dust mass. These values are strikingly similar to those for the dust emitted by the most primitive comets in the Solar System, even though ß Pictoris is more massive and more luminous and has a different planetary system architecture.

Intramedullary nailing in the treatment of open fractures of the tibia and fibula.

Intramedullary nailing of thirty acute displaced open fractures of the tibia and fibula resulted in union with only one superficial infection. The low incidence of sepsis is attributed to the use of the curved malleable Hodgkinson tibial nail which requires no reaming, renders the operation less difficult and traumatic, and interferes minimally with bone vascularity. Fibular nailing was an effective means of stabilizing nine of the twelve fractures close to the ankle joint.

Analysis of organophosphorus pesticides in rice by supercritical fluid extraction and quantitation using an atomic emission detector.

A rapid and sensitive method for the detection and quantitation of organophosphorus pesticides in rice has been developed. It uses extraction with methanol-modified supercritical carbon dioxide followed by quantitation by a gas chromatograph equipped with an atomic emission detector operating in the phosphorus and sulfur modes. Evaporative displacement of the collection solvent during the supercritical fluid extraction stage allows quantitation of the analyte down to 10 ng/g without any intermediate concentration steps.

Optimal signal-to-noise in digital phase lock amplifiers.

We derive an expression for the optimal signal-to-noise ratio for linear phase lock amplifiers. In its digital form the optimal method can be implemented by real-time signal processing techniques. We analyze in detail the case of detector-noise-limited systems finding that the optimal technique can be used to eliminate effectively the detector's time constant from the set of parameters determining the overall efficiency. This has important implications for optical detection system design. We also report an experimental verification of the optimal method, thus establishing its practicality.

Survival after free falls of 59 metres into water from the Sydney Harbour Bridge, 1930-1982.

Between 1930 and 1982, 92 persons fell from the Sydney Harbour Bridge into the water, 59 metres below. The major problem among survivors was pulmonary trauma, often with severe respiratory failure. The position of impact influenced survival, the feet-first vertical position being the most favourable. Mortality rate from the fall was 85%. Rapid clinical assessment of victims, especially with reference to pulmonary injury, and prompt institution of ventilatory support, where required, may reverse respiratory failure. Intra-abdominal injuries, spinal column or central nervous system involvement and peripheral fractures should all be suspected.

Ingestion of hashish oil-filled condoms.

Three cases of ingestion of condoms containing hashish oil are reviewed, these being the first reported in the Australian literature. Conservation management resulted in the uneventful passage per rectum of a total of 66 intact, drug-filled packages. There was no evidence of rupture of the condoms and ensuing intoxication, or of intestinal obstruction. Clear radiological evidence of a hashish oil-filled condom was present in only one of the three cases on admission to hospital. There are no recorded human fatalities from toxicity after cannabis ingestion, and drug-filled condoms will usually traverse the normal gastrointestinal tract spontaneously. A policy of non-intervention is advised only when the drug is known to be cannabis. Operative treatment is necessary in the presence of more potent substances such as cocaine, and also to relieve intestinal obstruction.

Three rare causes of extensor tendon rupture.

Three unusual cases of rupture of finger extensor tendons by attrition are reported. In one instance it was associated with long-standing nonunion of a scaphoid fracture, with a posttraumatic dorsal subluxation of the lower end of the ulna in another, and with a Madelung's deformity in the third. Extensor tendon rupture has not been previously recorded in the English-language literature after the first two conditions.

De Quervain's disease: surgical or nonsurgical treatment.

Ninety-one wrists in 82 consecutive patients with Quervain's disease were treated by the one surgeon between 1978 and 1987. The treatment of 79 wrists in 71 patients who had received their entire treatment from this surgeon is analyzed. Uniformity of injection technique is thus ensured. Initial treatment in 63 wrists was an injection of steroids and local anesthetic into the tendon sheath, which gave complete relief in 45 cases. Seven wrists received two injections before the pain abated. Only 11 of the 63 injected wrists had an operation. In 10 of these the extensor pollicis brevis tendon was in a separate compartment. It is concluded that injection of steroids is the preferred initial treatment in de Quervain's disease, giving complete and lasting relief in 80% of cases. If injection fails, it appears likely that the extensor pollicis brevis tendon lies in a separate compartment.

Envenomation by a King Island tiger snake (Notechis ater humphreysi).

A venomous King Island tiger snake (Notechis ater humphreysi)bit a herpetologist on the hand on the forty-eight floor of a Sydney city building. Prompt first-aid treatment, comprising the application of a wide constrictive bandage the length of the limb, combined with immobilisation, delayed central movement of the venom until resuscitative care and antivenom were available. The patient had received tiger-snake antivenom 16 years previously, and also suffered from atopic eczema. Administration of 6000 units of tiger-snake antivenom after parenteral administration of an antihistamine was uneventful. A transient rash on the second day and a mild urticarial rash on the twelfth day after envenomation may have been either serum reactions or allergic response to other medication.