Validation of a torsional balance for thrust measurements of Hall effect and microwave-based space propulsion systems.

A torsional thrust balance has been designed and validated by Surrey Space Centre and Added Value Solutions UK Ltd. in collaboration with the UK Space Agency. The thrust stand has been tested with two electric propulsion (EP) systems operating with xenon: the Halo thruster and the XJET thruster. The first consists of a low-power (<1 kW) Hall effect-based thruster, whose thrust level is between 3 and 20 mN, depending on the power of the system. The second is an electron cyclotron resonance thruster whose operative point is in the 0.3-1.5 mN thrust range. The thruster is mounted on a titanium rotating beam, whose movement is measured by an optical fiber displacement sensor. The thrusters' direct current electrical connections are routed through room temperature liquid metal pots and microwave power is transmitted via a wireless transfer system, minimizing friction effects. To reduce thermal issues during long thruster operations, the torsional thrust balance is designed with a water-cooling hub around the flex pivot. Noise from the laboratory environment is lessened by using four vibration-dampening spring systems as thrust balance feet. The tests on the two EP systems have shown accurate and repeatable results, demonstrating that the balance can be used to characterize different EP systems in the µN-mN thrust range.

A fibre-coupled UHV-compatible variable angle reflection-absorption UV/visible spectrometer.

We present a novel UV/visible reflection-absorption spectrometer for determining the refractive index, n, and thicknesses, d, of ice films. Knowledge of the refractive index of these films is of particular relevance to the astrochemical community, where they can be used to model radiative transfer and spectra of various regions of space. In order to make these models more accurate, values of n need to be recorded under astronomically relevant conditions, that is, under ultra-high vacuum (UHV) and cryogenic cooling. Several design considerations were taken into account to allow UHV compatibility combined with ease of use. The key design feature is a stainless steel rhombus coupled to an external linear drive (z-shift) allowing a variable reflection geometry to be achieved, which is necessary for our analysis. Test data for amorphous benzene ice are presented as a proof of concept, the film thickness, d, was found to vary linearly with surface exposure, and a value for n of 1.43 ± 0.07 was determined.

A multicentre randomized controlled trial of epidural corticosteroid injections for sciatica: the WEST study.

OBJECTIVE: To determine the effectiveness and predictors of response to lumbar epidural corticosteroid injections (ESI) in patients with sciatica. We performed a 12-month, multicentre, double-blind, randomized, placebo-controlled, parallel-group trial in four secondary pain-care clinics in the Wessex Region. METHODS: Two hundred and twenty-eight patients with a clinical diagnosis of unilateral sciatica of 1-18 months' duration were randomized to either three lumbar ESIs of triamcinolone acetonide or interligamentous saline injections at intervals of 3 weeks. The main outcome measure was the Oswestry low back pain disability questionnaire (ODQ). RESULTS: At 3 weeks, the ESI group demonstrated a transient benefit over the placebo group (patients achieving a 75% improvement in ODQ, 12.5 vs 3.7%; number needed to treat, 11.4). No benefit was demonstrated from 6 to 52 weeks. ESIs did not improve physical function, hasten return to work or reduce the need for surgery. There was no benefit of repeated ESIs over single injection. No clinical predictors of response were found. At the end of the study the majority of patients still had significant pain and disability regardless of intervention. CONCLUSIONS: In this pragmatic study, ESIs offered transient benefit in symptoms at 3 weeks in patients with sciatica, but no sustained benefits in terms of pain, function or need for surgery. Sciatica is a chronic condition requiring a multidisciplinary approach. To fully investigate the value of ESIs, they need to be evaluated as part of a multidisciplinary approach.

The pre-operative anaesthetic visit. Its value to the patient and the anaesthetist.

One hundred and thirty-two patients staying in hospital more than 24 h were visited pre- and postoperatively. Patients were asked a standard set of questions, and 39% could not remember accurately what they were asked. This has important medicolegal implications. In 15% of patients, information that significantly altered subsequent anaesthetic management was discovered, but in less than 3% would ignorance of the patient's condition have required postponement of the surgery. We conclude that the major reason for a pre-operative visit by an anaesthetist is that patients appreciate it, rather than it being medically necessary.

Delayed excitatory reaction following interaction of cocaine and monoamine oxidase inhibitor (phenelzine).

A case report is presented in which a patient receiving the monoamine oxidase inhibitor, phenelzine, developed a delayed excitatory reaction following administration of topical cocaine spray during anaesthesia for vocal cord surgery. The pharmacological basis of the drug interaction is discussed.

Transcutaneous electrical nerve stimulation after thoracotomy. Pain relief and peak expiratory flow rate--a trial of transcutaneous electrical nerve stimulation.

Forty patients scheduled to undergo thoracotomy were randomly allocated to receive either transcutaneous electrical nerve stimulation with intramuscular papaveretum (20 patients) or intramuscular papaveretum alone (20 patients) for postoperative pain relief. Total intramuscular analgesic requirements in the first 24 hours, time to satisfactory transfer to oral analgesia, antiemetic requirements and length of stay in hospital postoperatively were noted. Peak expiratory flow rate was compared pre- and postoperatively in the two groups. Use of nerve stimulation did not significantly alter the requirements for analgesia although there was a reduction in postoperative nausea and vomiting in the nerve stimulation group. There was no difference between the two groups with respect to changes in peak expiratory flow rate.