Abstract. A Lagrangian approach has been used to assess the degree of chemically induced ozone loss in the Arctic lower stratosphere in winter 1991/1992. Trajectory calculations are used to identify air parcels probed by two ozonesondes at different points along the trajectories. A statistical analysis of the measured differences in ozone mixing ratio and the time the air parcel spent in sunlight between the measurements provides the chemical ozone loss. Initial results were first described by von der Gathen et al. [1995]. Here we present a more detailed description of the technique and a more comprehensive discussion of the results. Ozone loss rates of up to 10 ppbv per sunlit hour (or 54 ppbv per day) were found inside the polar vortex on the 475 K potential temperature surface (about 19.5 km in altitude) at the end of January. The period of rapid ozone loss coincides and slightly lags a period when temperatures were cold enough for type I polar stratospheric clouds to form. It is shown that the ozone loss occurs exclusively during the sunlit portions of the trajectories. The time evolution and vertical distribution of the ozone loss rates are discussed.

Frequent attenders with medically unexplained symptoms account for levels of service use and expenditure that are comparable with other frequent attenders, but the use and cost of medical investigations in this group are significantly greater.

A comparison has been conducted of the height and sharpness of the tropopause as revealed by temperature and ozone profiles. In the study, 628 ECC-type ozonesonde profiles from four stations in northern Europe were used. Two tropopauses were defined for each profile: a thermal tropopause and an ozone tropopause defined in terms of both mixing ratio and vertical gradient of mixing ratio. On average, the ozone tropopause lay 800 m below the thermal. Large differences in tropopause height were associated with indefinite thermal tropopauses which were, in turn, often associated with cyclonic conditions (some corresponding to profiles taken within the stratospheric polar vortex). On almost all profiles the thermal tropopause was the higher of the two, and of the 15 profiles that did not fit this pattern, two-thirds were associated with anticyclonic flow in the upper troposphere. It is also shown that the tropopause definition impacts greatly on the evaluation of the ozone content of the troposphere. Where the thermal tropopause is indefinite in character, on average 27% of the ozone found below the thermal tropopause lies above the ozone tropopause.

Objective To estimate the prevalence of medically unexplained symptoms in patients who most frequently attend outpatient services. Design Retrospective cohort study over three years with review of case notes. Setting Secondary care services in the South Thames (West) NHS region. Participants Outpatient attenders with new appointments in 1993. Main outcome measures Number of outpatient appointments, and number of consultation episodes for medically unexplained conditions. Results Medical records of 361 of 400 sampled frequent attenders were examined, and 971 consultation episodes were recorded. Ninety seven (27%) had one or more consultation episodes in which the condition was medically unexplained; 208 (21%) of the 971 consultation episodes were medically unexplained. Abdominal pain, chest pain, headache, and back pain were commonly found to be medically unexplained. Conclusions Medically unexplained symptoms present in most hospital specialties and account for a considerable proportion of consultations by frequent attenders in secondary care.

National Institute for Health Research Health Technology Assessment Programme.

This review found that psychologic morbidity was a major determinant of insomnia in HIV infection. Further study would be of value in clarifying the role of other factors, as well as measuring the impact of insomnia on functioning and quality of life in this population.

GPs consider the management of patients with MUS to be an important part of their workload, but there is a perception that effective management strategies are lacking. Psychiatrists need to offer greater support and training for GPs in this area of health care.

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