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Biomedical subjects

P M Roth

Publications and source records attributed to P M Roth.

7 recordsLinked to original sources
PubMed2000

Fine particles and oxidant pollution: developing an agenda for cooperative research.

This paper describes a background for the North American Research Strategy for Tropospheric Ozone (NARSTO) cooperative program integrating studies of O3 and PM2.5. It discusses several important aspects for rationalizing NARSTO's trinational investigative approach, including (1) an outlook on the state of knowledge about fine particles in the troposphere and their origins in Canada, Mexico, and the United States; (2) the need for enhancement and strengthening of key field measurements in relation to tropospheric chemistry and a health effects component; and (3) the use of a central theme for advancing air quality modeling using evolving techniques to integrate and guide key process-oriented field campaigns. The importance of organizing a scientific program to acquire "policy-relevant" information is stressed, noting cooperative research directions that address combined PM2.5 and O3 issues, illustrated through exploration of hypothetical pathways of PM2.5 response to choices of O3 and PM precursor emission reductions. The information needed for PM2.5 research is noted to intersect in many cases with those of O3, but diverge in other cases. Accounting for these distinctions is important for developing NARSTO's strategy over the next decade.

Air Pollution↗
PubMed2000

The use of ambient measurements to identify which precursor species limit aerosol nitrate formation.

A thermodynamic equilibrium model was used to investigate the response of aerosol NO3 to changes in concentrations of HNO3, NH3, and H2SO4. Over a range of temperatures and relative humidities (RHs), two parameters provided sufficient information for indicating the qualitative response of aerosol NO3. The first was the excess of aerosol NH4+ plus gas-phase NH3 over the sum of HNO3, particulate NO3, and particulate SO4(2-) concentrations. The second was the ratio of particulate to total NO3 concentrations. Computation of these quantities from ambient measurements provides a means to rapidly analyze large numbers of samples and identify cases in which inorganic aerosol NO3 formation is limited by the availability of NH3. Example calculations are presented using data from three field studies. The predictions of the indicator variables and the equilibrium model are compared.

Aerosols↗
PubMed1993

Evaluation of prenatal diagnosis of congenital heart disease.

Prenatal diagnosis performed by fetal ultrasound scan is now a routine part of antenatal care in many countries. That an increasing number of fetal anomalies may be detected on prenatal ultrasound is beyond doubt. What is possible is not, however, always practical, especially when congenital heart diseases (CHDs) are concerned and when whole antenatal populations are screened rather than high-risk groups. Thanks to our registry of congenital anomalies, a retrospective study was undertaken to evaluate the prenatal detection of CHDs by ultrasound scan in 131,760 consecutive pregnancies of known outcome from 1979 to 1988. Only 84 out of 912 malformed fetuses with CHDs without chromosomal anomalies were detected (9.2 per cent). The sensitivity of detection varied from around 38 per cent for malformations such as hypoplastic left heart and single ventricle to around 5 per cent for ventricular and atrial septal defects. The effectiveness of the detection of some forms of major congenital heart disease has increased dramatically since 1987 by including routine examination of the four-chamber view and of the inflow and outflow tracts of the fetal heart. Our results stress the need to obtain a definite clear four-chamber view, to perform scans at > or = 18 weeks of gestation, and to train sonographers in order to improve the prenatal detection of CHDs.

Female↗
PubMed1986

Effect of transcutaneous electrical nerve stimulation for controlling pain associated with orthodontic tooth movement.

Transcutaneous electrical nerve stimulation (TENS) was assessed for its effect on periodontal pain associated with orthodontic separation. Forty-five adult subjects were randomly assigned to a TENS group, a placebo TENS group, and a control group. They were further subdivided into intraoral and extraoral electrode placement, and 1-, 2-, and 3-day treatment duration groups. In each patient orthodontic separators were placed mesial and distal to the upper first molars, bilaterally. Subjects were asked to rate their discomfort every 12 hours for 4 days with a 10 cm visual analogue scale. The results showed a significant decrease in reported pain for those subjects in the TENS group at the 24-, 36-, and 48-hour assessment periods as compared to either the placebo or control group. In the control group postseparation discomfort continued through the 60-hour assessment period. The present study suggests that TENS is an effective nonpharmacologic method of controlling postadjustment tooth pain.

Adult↗