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Richard Johnson

Publications and source records attributed to Richard Johnson.

27 records · Page 2Linked to original sources
PubMed2003

Forecasting peak daily ozone levels: part 2--A regression with time series errors model having a principal component trigger to forecast 1999 and 2002 ozone levels.

A modified time series approach, a Box-Jenkins regression with time series errors (RTSE) model plus a principal component (PC) trigger, has been developed to forecast peak daily 1-hr ozone (O3) in real time at the University of Wisconsin-Milwaukee North (UWM-N) during 1999 and 2002. The PC trigger acts as a predictor variable in the RTSE model. It tries to answer the question: will the next day be a possible high O3 day? To answer this question, three PC trigger rules were developed: (1) Hi-Low Checklist, (2) Discriminant Function Approach I, and (3) Discriminant Function Approach II. Also, a pure RTSE model without including the PC trigger and a persistence approach were tested for comparison. The RTSE model with DFA I successfully forecast the only two 1-hr federal exceedances (124 ppb), one in 1999 and one in 2002. In terms of the O3 100-ppb exceedances, 60-80% of the incorrect forecasts occurred with incorrect PC decisions. A few others may have been caused by unexpected O3-weather relations. When the three approaches used UWM-N data to forecast a 100-ppb exceedance somewhere in the Milwaukee, WI, metropolitan area, their performance was dramatically improved: the false alarm rate was reduced from 0.89 to 0.44, and the probability of detection was increased from 0.71 to 0.88.

Forecasting↗
PubMed2002

Suppression of tandem-multimer formation during genetic transformation of the mycotoxin-producing fungus Penicillium paxilli by disrupting an orthologue of Aspergillus nidulans uvsC.

An orthologue of Aspergillus nidulans uvsC and Saccharomyces cerevisiae RAD51 was cloned from the filamentous fungus, Penicillium paxilli. A mutation in uvsC causes UV sensitivity during germination. The product of RAD51 is involved in meiotic recombination and DNA damage repair. The deduced amino acid sequence of the product of this gene (Pprad51) shared 92% identity with UVSC. Site-specific disruption of pprad51 showed a significant effect for extra-cellular DNA integration. Transformation of the null mutant with pII99, which confers geneticin resistance, resulted in a shift from a predominance of direct repeats at a single site to single copies when compared with a control strain. A copy-number effect of integrated pII99 for geneticin selection was suggested as the frequency of direct repeat formation was less when selected at a lower concentration in the control strain. However, such an effect was not observed in the null mutant, further supporting an involvement of Pprad51 in direct repeat formation.

Aspergillus nidulans↗
PubMed2002

Development of case definitions for acute encephalopathy, encephalitis, and multiple sclerosis reports to the vaccine: Adverse Event Reporting System.

The Vaccine Adverse Event Reporting System (VAERS), administered by the FDA and CDC, is the U.S. system for surveillance of vaccine adverse events (AE). Acute encephalopathy age <18 months (EO < 18), age > or =18 months (EO > or = 18), encephalitis (EI), and multiple sclerosis (MS) after vaccination have been reported to VAERS, but reports often contain insufficient information to validate diagnoses. Standardized case definitions would enhance the utility of VAERS reports for AE surveillance. We developed practical case definitions for classification of VAERS reports, and three neurologists independently applied the definitions to reports submitted in 1993. Inter-observer agreement was assessed, and non-concordant classifications were reviewed in a follow-up conference call. Reports of EO < 18 (n = 8), EO > or = 18 (n = 20), EI (n = 15), and MS (n = 16) were classified as "definite" in 7% to 30% of the cases, while 26% to 51% of reports were thought to have insufficient information to make a classification. Agreement among reviewers was good to excellent, (kappa: 0.65 to 0.85) except for EO < 18 m for which it was marginal (kappa: 0.37). It is possible to develop reproducible case definitions for acute encephalopathy, encephalitis, and multiple sclerosis using a standardized approach. Application of standardized case definitions to VAERS reports documents the limited information in many reports, specifies data for supplemental collection, and indicates that VAERS reports should be cautiously interpreted. Development and application of case definitions for other adverse events reported after vaccination should enhance the value of vaccine safety databases. Published by Elsevier Science Inc.

Acute Disease↗
PubMed2002

Forecasting peak daily ozone levels--I. A regression with time series errors model having a principal component trigger to fit 1991 ozone levels.

This research was motivated by the need to warn the population of Milwaukee, WI, on high-ozone days. A statistical model for the peak daily 1-hr ozone level is proposed. A Regression with Time Series Errors (RTSE) model, which includes a principal component (PC) trigger, is the basis for forecasting the peak daily 1-hr ozone level. The RTSE model, with a PC trigger, is first employed to estimate daily peak ozone measured at the University of Wisconsin, Milwaukee-North (UWM-N), during the 1991 ozone season. The RTSE model uses peak daily temperature, morning vector average wind direction, and the PC trigger as predictor variables. The PC trigger was designed to summarize atmospheric circumstances when peak ozone was greater than 100 parts per billion (ppb). It is verified that the RTSE model, with a PC trigger, significantly improves the prediction of peak daily ozone, particularly peak ozone greater than 100 ppb. In comparison with the RTSE model without the PC trigger, the RTSE model with a PC trigger raised the R2 from 0.680 to 0.809. It is suggested that the RTSE model, with the PC trigger, is an adequate statistical model that has the potential for real-time ozone forecasting.

Air Pollutants↗