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Biomedical subjects

G J Frost

Publications and source records attributed to G J Frost.

At least 19 recordsLinked to original sources
PubMed2003

Fossil-fueled power plants as a source of atmospheric carbon monoxide.

Elevated carbon monoxide (CO) mixing ratios in excess of those derived from emissions inventories have been observed in plumes from one gas- and coal-fired power plant and three of four lignite coal-fired electric utility power plants observed in east and central Texas. Observations of elevated CO on days characterized by differing wind directions show that CO emissions from the lignite plants were relatively constant over time and cannot be ascribed to separate sources adjacent to the power plants. These three plants were found to be emitting CO at rates 22 to 34 times those tabulated in State and Federal emissions inventories. Elevated CO emissions from the gas- and coal-fired plant were highly variable on time scales of hours to days, in one case changing by a factor of 8 within an hour. Three other fossil-fueled power plants, including one lignite-fired plant observed during this study, did not emit substantial amounts of CO, suggesting that a combination of plant operating conditions and the use of lignite coal may contribute to the enhanced emissions. Observed elevated CO emissions from the three lignite plants, if representative of average operating conditions, represent an additional 30% of the annual total CO emissions from point sources for the state of Texas.

Air Pollutants↗
PubMed2003

Direct measurements of urban OH reactivity during Nashville SOS in summer 1999.

Emissions of volatile chemicals control the hydroxyl radical (OH), the atmosphere's main cleansing agent, and thus the production of secondary pollutants. Accounting for all of these chemicals can be difficult, especially in environments with mixed urban and forest emissions. The first direct measurements of the atmospheric OH reactivity, the inverse of the OH lifetime, were made as part of the Southern Oxidant Study (SOS) at Cornelia Fort Airpark in Nashville, TN in summer 1999. Measured OH reactivity was typically 11 s(-1). Measured OH reactivity was 1.4 times larger than OH reactivity calculated from the sum of the products of measured chemical concentrations and their OH reaction rate coefficients. This difference is statistically significant at the 1sigma uncertainty level of both the measurements and the calculations but not the 2sigma uncertainty level. Measured OH reactivity was 1.3 times larger than the OH reactivity from a model that uses measured ambient concentrations of volatile organic compounds (VOCs), NO, NO2, SO2, and CO. However, it was within approximately 10% of the OH reactivity from a model that includes hydrocarbon measurements made in a Nashville tunnel and scaled to the ambient CO at Cornelia Fort Airpark. These comparisons indicate that 30% of the OH reactivity in Nashville may come from short-lived highly reactive VOCs that are not usually measured in field intensive studies or by US EPA's Photochemical Assessment Monitoring Stations.

Air Pollutants↗
PubMed2001

Observations of ozone formation in power plant plumes and implications for ozone control strategies.

Data taken in aircraft transects of emissions plumes from rural U.S. coal-fired power plants were used to confirm and quantify the nonlinear dependence of tropospheric ozone formation on plume NO(x) (NO plus NO(2)) concentration, which is determined by plant NO(x) emission rate and atmospheric dispersion. The ambient availability of reactive volatile organic compounds, principally biogenic isoprene, was also found to modulate ozone production rate and yield in these rural plumes. Differences of a factor of 2 or greater in plume ozone formation rates and yields as a function of NO(x) and volatile organic compound concentrations were consistently observed. These large differences suggest that consideration of power plant NO(x) emission rates and geographic locations in current and future U.S. ozone control strategies could substantially enhance the efficacy of NO(x) reductions from these sources.

Journal Article↗
PubMed1991

The use of the objective structured clinical examination as an audit of teaching and student performance.

A four year experience of the Objective Structured Clinical Examination in Child Health of 301 students in 18 separate examination diets was analysed to determine student competence in several clinical examinations including cardiovascular and central nervous system, developmental examination, history of asthma and in answering multiple choice questions relating to factual information. Using criterion reference assessment, student performance was related to individual knowledge, quality of teaching, examination design and teacher expectation. Variable levels of expectation and achievement were noted for different clinical items. Staff expectation of student performance was found to be higher than achieved in 39%, the same in 55% and in only 6% did students perform better than was anticipated. The value of using Criterion Reference Assessment System, based on a standard comprehensive examination, is discussed in relation to influencing examination design and efficiency of teaching medical students.

Achievement↗
PubMed1986

A comparison between the neurological and intellectual abnormalities in children and adults with congenital hypothyroidism.

Standardised intellectual, motor and behavioural tests have been undertaken in a group of 73 children and 43 adults with congenital hypothyroidism in a regional study in the north of England. These provide comprehensive data with which to compare the results of studies of children diagnosed by screening and indicate the degree of abnormalities persisting into adult life in those patients diagnosed before screening was introduced. The mean IQ scores of the hypothyroid children and adults were 1-2 standard deviations (SD) below the population means. Longitudinal IQ data indicate persistence of intellectual abnormalities, though there was an increase in IQ score in several patients. The mean motor scores were reduced by 1-2 SD in the children and 1-3 SD in the adults. Behavioural problems and personality difficulties mainly of a neurotic nature also persisted into adult life.

Adolescent↗
PubMed1986

Dietary carbohydrate deficits and hypoglycaemia in the young diabetic on holiday.

On two British Diabetic Association Educational Holidays, 67 children aged 6-9 years had their diabetic management analysed and hypoglycaemic episodes recorded. The average pre-camp carbohydrate prescription of the children was found to be 44 g below minimal recommended values. Hypoglycaemic episodes were more frequent in those with greater carbohydrate deficits and morning insulin doses in excess of 0.7 U/kg. The management of the young diabetic at camp should include a pre-camp analysis with appropriate adjustment of diet and insulin to minimize hypoglycaemic crises. Guideline figures are proposed for average age-related carbohydrate intake.

Blood Glucose↗
PubMed1986

Diagnosis of exocrine pancreatic insufficiency in cystic fibrosis by use of fluorescein dilaurate test.

In the fluorescein dilaurate test fluorescein dilaurate is cleaved by the pancreas specific cholesterol ester hydrolase activity and the liberated fluorescein is absorbed and excreted in the urine. Fluorescein recovery is a reflection of exocrine pancreatic function. The test was evaluated in 14 patients with cystic fibrosis and 16 healthy volunteers. The test was well tolerated by patients, was easy to perform, and gave significantly lower values in the patients suffering from cystic fibrosis. The result of the pancreolauryl test was also correlated with the result of the faecal chymotrypsin test in 11 of the patients suffering from cystic fibrosis. A positive correlation was found between the two test results. The test is a practical and reliable index of pancreatic exocrine function and may have a useful role as a screening procedure.

Adolescent↗
PubMed1985

Management of patients with congenital hypothyroidism.

The biochemical state and treatment of 73 children and 44 adults up to the age of 40 with proved congenital hypothyroidism were assessed in a regional study in the north of England. The findings showed that a substantial proportion of the patients were having inappropriate treatment or were not taking their treatment regularly and that in some of these there were clinical effects.

Adolescent↗
PubMed1985

Pseudo-precocious puberty caused by bilateral idiopathic testicular hyperplasia.

A boy aged two years presenting with advanced development of the genitalia, but with prepubertal testes, and accelerated growth is described. Investigation indicated pseudo-precocious puberty, due to idiopathic interstitial cell hyperplasia. Difficulties in interpretation of the hormonal studies were encountered due to an aberrant left testicular vein. This rare condition which has been called Testotoxicosis is probably due to an inborn error of metabolism not yet identified.

Child, Preschool↗