Case studies of clear air turbulence using the diagnostic Richardson Number Tendency formulation

The results of four case studies of clear air turbulence (CAT) using the diagnostic Richardson number tendency (DRT) formulation are highlighted. The performance of this technique in resolving regions of documented CAT encounters is encouraging. Its operational adaptability appears particularly attractive in that input data can be supplied by the currently operational rawinsonde system. Two CAT indices are calculated deterministically, sensing synoptic scale changes in static stability and vertical wind shear conductive for supporting mesoscale CAT layers. These two indices reveal volumes of the troposphere which act as source regions for patches of CAT. The first, the time to reach the critical Richardson number necessary for the initiation of turbulent conditions, was first used by Oard (1974). A second index is devised which is an adaptation of Roach's (1970) work relating synoptic scale and mesoscale energetical coupling and gives more information on the relative intensity of these source regions. The output from the DRT computer module highlights specific regions of the atmosphere which can be interpreted operationally in terms of a CAT encounter probability

A concept for a fuel efficient flight planning aid for general aviation

A core equation for estimation of fuel burn from path profile data was developed. This equation was used as a necessary ingredient in a dynamic program to define a fuel efficient flight path. The resultant algorithm is oriented toward use by general aviation. The pilot provides a description of the desired ground track, standard aircraft parameters, and weather at selected waypoints. The algorithm then derives the fuel efficient altitudes and velocities at the waypoints

Design and performance of a multicentre, randomized controlled trial of teleconsulting.

We have designed and performed a multicentre, randomized controlled trial of teleconsulting. The trial investigated the effectiveness and cost implications in rural and inner-city settings of using videoconferencing as an alternative to general practitioner referral to a hospital specialist. The participating general practitioners referred a total of 3170 patients who satisfied the entry criteria. Of these, 1040 (33%) failed to provide consent or otherwise refused to participate in the trial. Of the patients recruited to the trial, a total of 1902 (91%) completed and returned the baseline questionnaire. Although the trial was successful in recruiting sufficient patients and in obtaining high questionnaire response rates, the findings will require careful interpretation to take account of the limits which the protocol placed on the ability of general practitioners to select patients for referral

Study of an attitude control system for the astronaut maneuvering unit final report, dec. 1963 - jul. 1964

Attitude control system for astronaut maneuvering unit

Joint teleconsultations (virtual outreach) versus standard outpatient appointments for patients referred by their general practitioner for a specialist opinion: a randomised trial.

BACKGROUND: The current model of general practitioner referral of patients to hospital specialists in the UK is sometimes associated with unnecessary duplication of investigations and treatments. We aimed to compare joint teleconsultations between general practitioners, specialists, and patients (virtual outreach) with standard outpatient referral. METHODS: Virtual outreach services were established in London and Shrewsbury. The general practitioners referred 3170 patients, of whom 2094 consented to participate in the study and were eligible for inclusion. 1051 patients were randomly assigned virtual outreach, and 1043 standard outpatient appointments. We followed up the patients for 6 months after their index consultation. The primary outcome measure was the offer of a follow-up outpatient appointment. Analysis was by intention to treat. FINDINGS: More patients in the virtual outreach group than the standard group were offered a follow-up appointment (502 [52%] vs 400 [41%], odds ratio 1.52 [95% CI 1.27-1.82], p<0.0001). Significant differences in effects were observed between the two sites (p=0.009) and across different specialties (p<0.0001). Virtual outreach increased the offers of follow-up appointments more in Shrewsbury than in London, and more in ear, nose, and throat surgery and orthopaedics than in the other specialties. Fewer tests and investigations were ordered in the virtual outreach group by an average of 0.79 per patient (0.37-1.21, p=0.0002). Patients' satisfaction (analysed per protocol) was greater after a virtual outreach consultation than after a standard outpatient consultation (mean difference 0.33 scale points [95% CI 0.23-0.43], p<0.0001), with no heterogeneity between specialties or sites. INTERPRETATION: The trial showed that allocation of patients to virtual outreach consultations is variably associated with increased offers of follow-up appointments according to site and specialty, but leads to significant increases in patients' satisfaction and substantial reductions in tests and investigations. Efficient operation of such services will require appropriate selection of patients, significant service reorganisation, and provision of logistical support

External and internal noise surveys of London primary schools

Internal and external noise surveys have been carried out around schools in London, UK, to provide information on typical levels and sources to which children are exposed while at school. Noise levels were measured outside 142 schools, in areas away from flightpaths into major airports. 86% of the schools surveyed were exposed to noise from road traffic, the average external noise level outside a school being 57 dB LAeq. Detailed internal noise surveys have been carried out in 140 classrooms in 16 schools, together with classroom observations. It was found that noise levels inside classrooms depend upon the activities in which the children are engaged, with a difference of 20 dB LAeq between the 'quietest' and 'noisiest' activities. The average background noise level in classrooms exceeds the level recommended in current standards. The number of children in the classroom was found to affect noise levels. External noise influenced internal noise levels only when children were engaged in the quietest classroom activities. The effects of the age of the school buildings and types of window upon internal noise were examined but results were inconclusive

A demonstration of unified TDRS/GPS tracking and orbit determination

We describe results from an experiment in which TDRS and GPS satellites were tracked simultaneously from a small (3 station) ground network in the western United States. We refer to this technique as 'GPS-like tracking' (GLT) since the user satellite - in this case TDRS - is essentially treated as a participant in the GPS constellation. In the experiment, the TDRS K(sub space-to-ground link (SGL) was tracked together with GPS L-band signals in enhanced geodetic-quality GPS receivers (TurboRogue). The enhanced receivers simultaneously measured and recorded both the TDRS SGL and the GPS carrier phases with sub-mm precision, enabling subsequent precise TDRS orbit determination with differential GPS techniques. A small number of calibrated ranging points from routine operations at the TDRS ground station (White Sands, NM) were used to supplement the GLT measurements in order to improve determination of the TDRS longitude. Various tests performed on TDRS ephemerides derived from data collected during this demonstration - including comparisons with the operational precise orbit generated by NASA Goddard Space Flight Center - provide evidence that the TDRS orbits have been determined to better than 25 m with the GLT technique