Estimated effects of temperature on secondary organic aerosol concentrations

The temperature-dependence of secondary organic aerosol (SOA) concentrations is explored using an absorptive-partitioning model under a variety of simplified atmospheric conditions. Experimentally determined partitioning parameters for high yield aromatics are used. Variation of vapor pressures with temperature is assumed to be the main source of temperature effects. Known semivolatile products are used to define a modeling range of vaporization enthalpy of 10-25 kcal/mol-1. The effect of diurnal temperature variations on model predictions for various assumed vaporization enthalpies, precursor emission rates, and primary organic concentrations is explored. Results show that temperature is likely to have a significant influence on SOA partitioning and resulting SOA concentrations. A 10 degrees C decrease in temperature is estimated to increase SOA yields by 20-150%, depending on the assumed vaporization enthalpy. In model simulations, high daytime temperatures tend to reduce SOA concentrations by 16-24%, while cooler nighttime temperatures lead to a 22-34% increase, compared to constant temperature conditions. Results suggest that currently available constant temperature partitioning coefficients do not adequately represent atmospheric SOA partitioning behavior. Air quality models neglecting the temperature dependence of partitioning are expected to underpredict peak SOA concentrations as well as mistime their occurrence.

Children with psychiatric disorders who are frequent attenders to primary care

Child psychiatric disorder has been found to be linked to enhanced primary care attendance. We studied the somatic and psychological associations of psychiatric disorder amongst frequent (four or more consultations a year) primary care attending school children. We compared 32 children aged 7-12 years with a psychiatric disorder with 77 non-disordered (also frequently attending) children. Psychiatric disorder was not associated with type of presenting complaint at the surgery nor with chronic physical illness. However disordered children were more likely to be described by their mothers as handicapped by existing physical problems, in poor health, with low energy levels and likely to experience physical symptoms under stress. Problems in social relationships and educational difficulties were reported in more disordered children; more of them came from broken homes and had mothers who reported other psycho-social and health stresses and showed characteristic health beliefs. The findings indicate that knowledge about the child's general physical well-being and relationships and about maternal mental health may assist in the primary care identification and management of psychiatric disorders of frequently attending schoolchildren.

Psychiatric morbidity among children who are frequent attenders in general practice

This two-part cross-sectional study set out to determine the frequency and nature of psychiatric disorder among children aged seven to 12 years who were frequent attenders at one of two general practices. The first part of the study was an interview survey with a sample of 109 children who attended frequently (four or more times in one year) and 23 children who had not attended in one year. Descriptive information from a structured parental interview was used to diagnose childhood psychiatric disorder. The second part of the study was a postal survey with a sample of 194 children selected independently of frequency of attendance. The children's score on a parental screening questionnaire was used to determine probable psychiatric disorder. The response rates were 78% and 75% for the interview and postal studies, respectively. Of the children aged seven to 12 years registered with the two practices 21% were found to be frequent attenders. Attendances by frequent attenders accounted for 51% of all attendances in this age group. Psychiatric disorder was more common among frequent attenders than non-attenders (29% versus 9%, P < 0.05). Most of the psychiatric disorders were of an emotional nature (63%). The postal survey revealed that 15% of the children in this age group had a probable psychiatric disorder. It can therefore be estimated that 40% of children in the population with psychiatric disorder were frequent attenders.(ABSTRACT TRUNCATED AT 250 WORDS)

Improving the skills of established general practitioners: the long-term benefits of group teaching

This study set out to determine the long-term benefits of teaching psychiatric interview skills. Nine established general practitioners, eight of whom were also trainers, took part some 18 months after attending a problem-based interviewing course. Interview skills were assessed by rating behaviour during 10-minute videorecorded simulated consultations with role-players, recorded before and after training and at follow-up. The finding of an earlier study that, in terms of the course model, training successfully modified the doctor's behaviour, was largely replicated. In addition, not only were acquired skills maintained but further change took place during the follow-up period, change that can be seen as improvement in terms of the course model.