Michael Hannigan - Academia.edu (original) (raw)
Papers by Michael Hannigan
2013 IEEE 39th Photovoltaic Specialists Conference (PVSC), 2013
Environmental science & technology, Jan 19, 2014
To quantify and minimize the influence of gas/particle (G/P) partitioning on receptor-based sourc... more To quantify and minimize the influence of gas/particle (G/P) partitioning on receptor-based source apportionment using particle-phase semivolatile organic compound (SVOC) data, positive matrix factorization (PMF) coupled with a bootstrap technique was applied to three data sets mainly composed of "measured-total" (measured particle- + gas-phase), "particle-only" (measured particle-phase) and "predicted-total" (measured particle-phase + predicted gas-phase) SVOCs to apportion carbonaceous aerosols. Particle- (PM2.5) and gas-phase SVOCs were collected using quartz fiber filters followed by PUF/XAD-4/PUF adsorbents and measured using gas chromatography-mass spectrometry (GC-MS). Concentrations of gas-phase SVOCs were also predicted from their particle-phase concentrations using absorptive partitioning theory. Five factors were resolved for each data set, and the factor profiles were generally consistent across the three PMF solutions. Using a previous sour...
The Professional Protection Officer, 2010
Journal of the Air & Waste Management Association, 2013
In studies of coarse particulate matter (PM 10-2.5 ), mass concentrations are often estimated thr... more In studies of coarse particulate matter (PM 10-2.5 ), mass concentrations are often estimated through the subtraction of PM 2.5 from collocated PM 10 tapered element oscillating microbalance (TEOM) measurements. Though all field instruments have yet to be updated, the Filter Dynamic Measurement System (FDMS) was introduced to account for the loss of semivolatile material from heated TEOM filters. To assess errors in PM 10-2.5 estimation when using the possible combinations of PM 10 and PM 2.5 TEOM units with and without FDMS, data from three monitoring sites of the Colorado Coarse Rural-Urban Sources and Health (CCRUSH) study were used to simulate four possible subtraction methods for estimating PM 10-2.5 mass concentrations. Assuming all mass is accounted for using collocated TEOMs with FDMS, the three other subtraction methods were assessed for biases in absolute mass concentration, temporal variability, spatial correlation, and homogeneity. Results show collocated units without FDMS closely estimate actual PM 10-2.5 mass and spatial characteristics due to the very low semivolatile PM 10-2.5 concentrations in Colorado. Estimation using either a PM 2.5 or PM 10 monitor without FDMS introduced absolute biases of 2.4 µg/m 3 (25%) to -2.3 µg/m 3 (-24%), respectively. Such errors are directly related to the unmeasured semivolatile mass and alter measures of spatiotemporal variability and homogeneity, all of which have implications for the regulatory and epidemiology communities concerned about PM 10-2.5 . Two monitoring sites operated by the state of Colorado were considered for inclusion in the CCRUSH acute health effects study, but concentrations were biased due to sampling with an FDMS-equipped PM 2.5 TEOM and PM 10 TEOM not corrected for semivolatile mass loss. A regression-based model was developed for removing the error in these measurements by estimating the semivolatile concentration of PM 2.5 from total PM 2.5 concentrations. By estimating nonvolatile PM 2.5 concentrations from this relationship, PM 10-2.5 was calculated as the difference between nonvolatile PM 10 and PM 2.5 concentrations.
Atmospheric Environment, 2012
h i g h l i g h t s < Sources of carbonaceous PM2.5 were resolved using Positive Matrix Factoriza... more h i g h l i g h t s < Sources of carbonaceous PM2.5 were resolved using Positive Matrix Factorization, PMF. < A 7 factor solution was obtained for a set of data pooled across the 4 urban sites. < Spatial variability of factor contributions was assessed. < A bootstrap technique was coupled with PMF model for modeling uncertainty assessment. < PMF solutions for site-specific datasets were compared with the pooled data solution.
Atmospheric Environment, 2013
This study presents source apportionment results for PM 2.5 from applying positive matrix factori... more This study presents source apportionment results for PM 2.5 from applying positive matrix factorization (PMF) to a 32-month series of daily PM 2.5 compositional data from Denver, CO, including concentrations of sulfate, nitrate, bulk elemental carbon (EC) and organic carbon (OC), and 51 organic molecular markers (OMMs). An optimum 8-factor solution was determined primarily based on the interpretability of the PMF results and rate of matching factors from bootstrapped PMF solutions with those from the base case solution. These eight factors were identified as inorganic ion, n-alkane, EC/sterane, light n-alkane/polycyclic aromatic hydrocarbon (PAH), medium alkane/alkanoic acid, PAH, winter/methoxyphenol and summer/odd n-alkane. The inorganic ion factor dominated the reconstructed PM 2.5 mass (sulfate + nitrate + EC + OC) in cold periods (daily average temperature < 10 °C; 43.7% of reconstructed PM 2.5 mass) whereas the summer/odd n-alkane factor dominated in hot periods (> 20 °C; 53.1%). The two factors had comparable relative contributions of 26.5% and 27.1% in warm periods with temperatures between 10 °C and 20 °C. Each of the seven factors resolved in a previous study (Dutton et al., 2010b) using a 1-year data set from the same location matches one factor from the current work based on comparing factor profiles. Six out of the seven matched pairs of factors are linked to similar source classes as suggested by the strong correlations between factor contributions (r = 0.89 − 0.98). Temperature-stratified source apportionment was conducted for three subsets of the data in the current study, corresponding to the cold, warm and hot periods mentioned above. The cold period (7-factor) solution exhibited a similar distribution of reconstructed PM 2.5 mass as the full data set solution. The factor contributions of the warm period (7-factor) solution were well correlated with those from the full data set solution (r = 0.76 − 0.99). However, the reconstructed PM 2.5 mass was distributed more to inorganic ion, n-alkane and medium alkane/alkanoic acid factors in the warm period solution than in the full data set solution. For the hot period (6-factor) solution, PM 2.5 mass distribution was quite different from that of the full data set solution, as illustrated by regression slopes as low as 0.2 and as high as 4.8 of each matched pair of factors across the two solutions.
Atmospheric Environment, 2012
h i g h l i g h t s < Concentrations of PM 2.5 associated carbonaceous species were measured from... more h i g h l i g h t s < Concentrations of PM 2.5 associated carbonaceous species were measured from 4 urban sites in Denver. < Spatial variability was assessed using the Pearson correlation coefficient (r) and coefficient of divergence (COD). < Near-highway sites exhibited higher concentrations of EC, OC, PAHs, and steranes than residential sites. < Large uncertainties associated with sampling and species quantification will bias the estimation of r and CODs. < CODs derived from co-located samples are useful points of reference to analyze spatial variability of PM 2.5 species.
Atmospheric Environment, 2002
... Steven G. Brown a , 1 , Pierre Herckes a , Lowell Ashbaugh b , Michael P. Hannigan a , 2 , So... more ... Steven G. Brown a , 1 , Pierre Herckes a , Lowell Ashbaugh b , Michael P. Hannigan a , 2 , Sonia M. Kreidenweis a and Jeffrey L ... The Big Bend Regional Aerosol and Visibility Observational (BRAVO) Study was conducted in Big Bend National Park, Texas, July through October ...
Cell, 2003
Efficient chemotaxis requires directional sensing and cell polarization. We describe a signaling ... more Efficient chemotaxis requires directional sensing and cell polarization. We describe a signaling mechanism involving G beta gamma, PAK-associated guanine nucleotide exchange factor (PIX alpha), Cdc42, and p21-activated kinase (PAK) 1. This pathway is utilized by chemoattractants to regulate directional sensing and directional migration of myeloid cells. Our results suggest that G beta gamma binds PAK1 and, via PAK-associated PIX alpha, activates Cdc42, which in turn activates PAK1. Thus, in this pathway, PAK1 is not only an effector for Cdc42, but it also functions as a scaffold protein required for Cdc42 activation. This G beta gamma-PAK1/PIX alpha/Cdc42 pathway is essential for the localization of F-actin formation to the leading edge, the exclusion of PTEN from the leading edge, directional sensing, and the persistent directional migration of chemotactic leukocytes. Although ligand-induced production of PIP(3) is not required for activation of this pathway, PIP(3) appears to localize the activation of Cdc42 by the pathway.
Environmental science & technology, 2007
Size distributions of particulate hopanes, steranes, and polycyclic aromatic hydrocarbons (PAHs) ... more Size distributions of particulate hopanes, steranes, and polycyclic aromatic hydrocarbons (PAHs) were measured in the exhaust from four heavy-duty diesel vehicles (HDDVs) operated under idle, creep, transient, and two highspeed driving modes. Particulate matter was collected using a chassis dynamometer and a dilution sampling system equipped with cascade impactors and filter samplers. Samples were extracted using organic solvents and analyzed using gas chromatography-mass spectrometry. Size distributions of hopanes and steranes were functions of engine load conditions and vehicle technology. Hopanes and steranes peaked in size ranges larger than 0.18 µm aerodynamic particle diameter under light load conditions and less than 0.10 µm aerodynamic particle diameter under heavier load conditions. The eight hopane size distributions emitted from newer technology (>1998) vehicles were unimodal while the four hopane size distributions emitted from older technology vehicles (<1992) were bimodal. Similar trends between older and newer vehicles were not observed for sterane size distributions. The PAH composition emitted from HDDVs was a function of driving cycle and vehicle technology. Light driving cycles produced quantifiable emissions of 3, 4, 5, and 6 ring PAHs (including coronene). Heavier driving cycles produced only the 3 and 4 ring PAHs in quantifiable amounts. PM1.8 and PM0.1 source profiles constructed using the relative abundance of hopanes and steranes to total organic carbon were functions of vehicle load condition. Increasing load reduced the relative abundance of motor oil tracers in the PM1.8 size fraction and increased the abundance of these tracers in the PM0.1 size fraction. The relative abundances of PAHs in the PM0.1 and PM1.8 size fractions emitted from the oldest vehicle tested (1985 HDDV) were significantly higher than for any other vehicle tested.
Environmental science & technology, 2012
To evaluate the utility and consistency of different speciation data sets in source apportionment... more To evaluate the utility and consistency of different speciation data sets in source apportionment of PM(2.5), positive matrix factorization (PMF) coupled with a bootstrap technique for uncertainty assessment was applied to four different 1-year data sets composed of bulk species, bulk species and water-soluble elements (WSE), bulk species and organic molecular markers (OMM), and all species. The five factors resolved by using only the bulk species best reproduced the observed concentrations of PM(2.5) components. Combining WSE with bulk species as PMF inputs also produced five factors. Three of them were linked to soil, road dust, and processed dust, and together contributed 26.0% of reconstructed PM(2.5) mass. A 7-factor PMF solution was identified using speciated OMM and bulk species. The EC/sterane and summertime/selective aliphatic factors had the highest contributions to EC (39.0%) and OC (53.8%), respectively. The nine factors resolved by including all species as input data are consistent with those from the previous two solutions (WSE and bulk species, OMM and bulk species) in both factor profiles and contributions (r = 0.88-1.00). The comparisons across different solutions indicate that the selection of input data set may depend on the PM components or sources of interest for specific source-oriented health study.
Environmental health perspectives, 2012
Neurotoxicology and teratology, 2013
We modeled binge patterns of high-dose toluene abuse during gestation in rats.We examined the beh... more We modeled binge patterns of high-dose toluene abuse during gestation in rats.We examined the behavioral and morphological impact of prenatal toluene in offspring.Toluene caused poor perinatal outcome, malformations and neonatal death.Results suggest that gestational toluene abuse may yield similar outcomes in humans.Binge Toluene Exposure in Pregnancy and Pre-weaning Developmental Consequences in Rats. Bowen, S.E. and Hannigan, J.H. The persistent rate of abuse of inhaled organic solvents, especially among women of child-bearing age, raises the risk for teratogenic effects of maternal toluene abuse. In this study, timed-pregnant Sprague Dawley rats were exposed from Gestation Day (GD) 8 to GD20 to 12,000 or 8000 parts per million (ppm) toluene, or 0 ppm (controls) for 30 min twice daily, 60 min total daily exposure. Pups were assessed from postnatal day (PN) 4 to PN21 using a developmental battery measuring growth (i.e., body weight), maturational milestones (e.g., eye opening & incisor eruption), and biobehavioral development (e.g., negative geotaxis & surface righting). Pups exposed in utero to 12,000 ppm or 8000 ppm toluene weighed significantly less than the non-exposed control pups beginning at PN4 and PN12 (respectively) until PN21. Toluene resulted in significant increases in an index of poor perinatal outcome, specifically a composite of malformations, defined “runting” and neonatal death. No significant delays were observed in reaching maturational milestones. The results reveal that brief, repeated, prenatal exposure to high concentrations of toluene can cause growth retardation and malformations in rats. A comparison of the present, conservative results with findings in previous studies implies that binge patterns of toluene exposure in pregnant rats modeling human solvent abuse can result in developmental and morphological deficits in offspring. These results do not exclude the possibility that maternal toxicity as well as teratogenic effects of toluene may contribute to outcomes. The results suggest that abuse of inhaled organic solvents like toluene may result in similar early developmental outcomes in humans.
Journal of dentistry, 2013
Best practice a b s t r a c t
International journal of nursing studies, 2013
This paper critically discusses the challenges mental health nurses face in trying to achieve a b... more This paper critically discusses the challenges mental health nurses face in trying to achieve a balance between fulfilling biomedical and social roles. We suggest that dilemmas exist for nurses in attempting to combine both approaches in their practice.
QJM : monthly journal of the Association of Physicians, 2013
Background: Gout and serum uric acid are associated with mortality but their simultaneous contrib... more Background: Gout and serum uric acid are associated with mortality but their simultaneous contributions have not been fully evaluated in the general population. Purpose: To explore the independent and conjoint relationships of gout and uric acid with mortality in the US population. Methods: Mortality risks of gout and serum uric acid were determined for 15 773 participants, aged 20 years or older, in the Third National Health and Nutrition Examination Survey by linking baseline information collected during 1988-1994 with mortality data up to 2006. Multivariable Cox proportional hazards regression determined adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for each exposure and all analyses were conducted in 2011 and 2012. Results: Compared with subjects without a history of gout, the multivariable HR for subjects with gout were 1.42 (CI 1.12-1.82) for total and 1.58 (CI 1.13-2.19) for cardiovascular mortality. Adjusted HRs per 59.5 mmol/l (1 mg/dl) increase in uric acid were 1.16 (CI 1.10-1.22) for total and cardiovascular mortality and this pattern was consistent across disease categories. In the conjoint analysis, the adjusted HRs for mortality in the highest two uric acid quartiles were 1.64 (CI 1.08-2.51) and 1.77 (CI 1.23-2.55), respectively, for subjects with gout, and were 1.09 (CI 0.87-1.37) and 1.37 (CI (1.11-1.70), respectively, for subjects without gout, compared with those without gout in the lowest quartile. A similar pattern emerged for cardiovascular mortality. Conclusions: Gout and serum uric acid independently associate with total and cardiovascular mortality. These risks increase with rising uric acid concentrations.
Journal of exposure science & environmental epidemiology, 2013
The US Environmental Protection Agency air pollution monitoring data have been a valuable resourc... more The US Environmental Protection Agency air pollution monitoring data have been a valuable resource commonly used for investigating the associations between short-term exposures to PM2.5 chemical components and human health. However, the temporally sparse sampling on every third or sixth day may affect health effect estimation. We examined the impact of non-daily monitoring data on health effect estimates using daily data from the Denver Aerosol Sources and Health (DASH) study. Daily concentrations of four PM2.5 chemical components (elemental and organic carbon, sulfate, and nitrate) and hospital admission counts from 2003 through 2007 were used. Three every-third-day time series were created from the daily DASH monitoring data, imitating the US Speciation Trend Network (STN) monitoring schedule. A fourth, partly irregular, every-third-day time series was created by matching existing sampling days at a nearby STN monitor. Relative risks (RRs) of hospital admissions for PM2.5 components at lags 0-3 were estimated for each data set, adjusting for temperature, relative humidity, longer term temporal trends, and day of week using generalized additive models, and compared across different sampling schedules. The estimated RRs varied somewhat between the non-daily and daily sampling schedules and between the four non-daily schedules, and in some instances could lead to different conclusions. It was not evident which features of the data or analysis were responsible for the variation in effect estimates, although seeing similar variability in resampled data sets with relaxation of the every-third-day constraint suggests that limited power may have had a role. The use of non-daily monitoring data can influence interpretation of estimated effects of PM2.5 components on hospital admissions in time-series studies.
The Science of the total environment, 2013
PM10–2.5 is more variable than PM2.5, acting as the major driver for PM10 extremes.Either PM10–2.... more PM10–2.5 is more variable than PM2.5, acting as the major driver for PM10 extremes.Either PM10–2.5 or PM2.5 can be the major driver for mean PM10 depending on site.Harvest and planting affect PM10–2.5, but do not have a strong influence on PM2.5.Year-specific data of agricultural activities are essential for emission estimates.PM10–2.5 and PM2.5 from traffic sources seem to be emitted by different processes.The characteristics of concentrations of PM10–2.5, PM2.5, and PM10 at 77 sites in the United States are evaluated. PM10 concentrations show strong spatial variability, with highest levels occurring in the southwestern United States, driven primarily by PM10–2.5. PM10–2.5 and PM2.5 concentrations show different spatial patterns. The highest concentrations of PM10–2.5 were observed at sites in the southwestern US, leading to the highest PM10 concentrations there. The PM2.5 concentrations are the major contributors to the average PM10 concentrations at many sites in the eastern United States. Poor correlations were generally found between PM10–2.5 and PM2.5, suggesting that PM10–2.5 and PM2.5 are generally influenced by different sources. PM10–2.5 is generally more variable than PM2.5 because PM10–2.5 has a higher deposition velocity and is primarily emitted from mechanical processes (e.g. agricultural harvest and construction) that are more influenced by factors including human operation and wind speed leading to a strong episodic nature. As a result of its high variability, PM10–2.5 acts as the major driver for PM10 extremes. PM10–2.5 is significantly correlated with PM10 at all investigated sites, with the average correlation value R2 = 0.79. Correlations of PM2.5 with PM10 (average of 0.37) are overall considerably lower than those between PM10–2.5 and PM10. Different seasonal, weekly, and diurnal patterns were observed between PM10–2.5 and PM2.5 at agricultural, on-road traffic, quarrying, airport, and marine sites. At investigated agricultural sites, while the concentrations of PM2.5 are higher in winter when there are few agricultural activities, PM10–2.5 concentrations are lower in winter months than in summer and autumn months, with highest levels corresponding to harvest and planting. The harvest and planting signatures were not observed in PM2.5 concentrations at any of these sites, suggesting that agricultural activities do not have a strong influence on PM2.5 concentrations.
Neurotoxicology and Teratology, 2007
Gestational Toluene Exposure Effects on Spontaneous and Amphetamine-Induced Locomotor Behavior in... more Gestational Toluene Exposure Effects on Spontaneous and Amphetamine-Induced Locomotor Behavior in Rats. Bowen, S.E., Mohammadi, M.H., Batis, J.C., and Hannigan, J.H. Neurotoxicology and Teratology, XX, 2006. The abuse of volatile organic solvents (inhalants) continues to be a major health concern throughout the world. Toluene, which is found in many products such as glues and household cleaners, is among the most commonly abused organic solvents. The neurobehavioral teratogenic sequelae of solvent abuse (i.e., repeated, brief inhalation exposures to very high concentrations of solvents) have not been examined thoroughly. In a preclinical model of inhalant abuse, timed-pregnant Sprague-Dawley rats were exposed to 0, 8000, or 12,000 parts per million (ppm) for 15 min twice daily from gestation day 8 (GD8) through GD20. In the first experiment, separate groups of offspring were observed individually in an open-field on postnatal day 22 (PN22), PN42 or PN63. In the second experiment, other offspring given identical prenatal toluene exposures were observed in an “open-field” following an acute i.p. injection of amphetamine (0, 0.56, 1.78 mg/kg) on PN28. Automated measurements of distance traveled and ambulatory time were recorded. Prenatal toluene exposure resulted in small alterations in spontaneous activity compared to non-exposed rats. Prenatal exposure to 12,000 ppm toluene resulted in significant hyposensitivity to the locomotor stimulatory effects of the amphetamine challenge in male but not female rats on PN28. The results demonstrate that prenatal exposure to abuse patterns of high concentrations of toluene through inhalation can alter spontaneous and amphetamine-induced locomotor behavior in rats. The expression of these effects also appears to depend upon the postnatal age of testing. These results imply that abuse of organic solvents during pregnancy in humans may also produce long-lasting effects on biobehavioral development.
Journal of Thoracic and Cardiovascular Surgery, 2011
Integrin-linked kinase, which is relevant to neoplastic transformation, is highly expressed in ma... more Integrin-linked kinase, which is relevant to neoplastic transformation, is highly expressed in malignant pleural mesothelioma. Recently, detection of integrin-linked kinase in serum of patients with ovarian cancer has been reported. This study asks whether integrin-linked kinase can also be detected in serum of patients with malignant pleural mesothelioma and whether serum level has diagnostic or prognostic relevance for that disease.A sandwich enzyme-linked immunosorbent assay was designed to detect integrin-linked kinase and applied to serum samples from 46 patients with malignant pleural mesothelioma, 98 patients with other malignant chest disease, and 23 patients with benign chest disease. Integrin-linked kinase serum concentration and clinical data were correlated statistically.Median serum integrin-linked kinase concentration was significantly higher in malignant pleural mesothelioma (8.89 ng/mL) than in other malignant chest disease (0.66 ng/mL) or benign chest disease (0.78 ng/mL, P < .001). There was no relevant correlation of serum integrin-linked kinase with cell lysis parameters (R2 < 0.1). Serum integrin-linked kinase concentration greater than 2.48 ng/mL had diagnostic sensitivity of 80%, specificity of 95%, positive predictive value of 85.7%, negative predictive value of 92.7%, and overall accuracy of 91% for distinction between malignant pleural mesothelioma and other diseases. Serum integrin-linked kinase concentration in malignant pleural mesothelioma was independent of histologic subtype or asbestos exposure. There was no statistically significant impact of serum integrin-linked kinase concentration on prognosis.Integrin-linked kinase can be detected in serum of patients with malignant pleural mesothelioma and may be a diagnostic marker for the disease.
2013 IEEE 39th Photovoltaic Specialists Conference (PVSC), 2013
Environmental science & technology, Jan 19, 2014
To quantify and minimize the influence of gas/particle (G/P) partitioning on receptor-based sourc... more To quantify and minimize the influence of gas/particle (G/P) partitioning on receptor-based source apportionment using particle-phase semivolatile organic compound (SVOC) data, positive matrix factorization (PMF) coupled with a bootstrap technique was applied to three data sets mainly composed of "measured-total" (measured particle- + gas-phase), "particle-only" (measured particle-phase) and "predicted-total" (measured particle-phase + predicted gas-phase) SVOCs to apportion carbonaceous aerosols. Particle- (PM2.5) and gas-phase SVOCs were collected using quartz fiber filters followed by PUF/XAD-4/PUF adsorbents and measured using gas chromatography-mass spectrometry (GC-MS). Concentrations of gas-phase SVOCs were also predicted from their particle-phase concentrations using absorptive partitioning theory. Five factors were resolved for each data set, and the factor profiles were generally consistent across the three PMF solutions. Using a previous sour...
The Professional Protection Officer, 2010
Journal of the Air & Waste Management Association, 2013
In studies of coarse particulate matter (PM 10-2.5 ), mass concentrations are often estimated thr... more In studies of coarse particulate matter (PM 10-2.5 ), mass concentrations are often estimated through the subtraction of PM 2.5 from collocated PM 10 tapered element oscillating microbalance (TEOM) measurements. Though all field instruments have yet to be updated, the Filter Dynamic Measurement System (FDMS) was introduced to account for the loss of semivolatile material from heated TEOM filters. To assess errors in PM 10-2.5 estimation when using the possible combinations of PM 10 and PM 2.5 TEOM units with and without FDMS, data from three monitoring sites of the Colorado Coarse Rural-Urban Sources and Health (CCRUSH) study were used to simulate four possible subtraction methods for estimating PM 10-2.5 mass concentrations. Assuming all mass is accounted for using collocated TEOMs with FDMS, the three other subtraction methods were assessed for biases in absolute mass concentration, temporal variability, spatial correlation, and homogeneity. Results show collocated units without FDMS closely estimate actual PM 10-2.5 mass and spatial characteristics due to the very low semivolatile PM 10-2.5 concentrations in Colorado. Estimation using either a PM 2.5 or PM 10 monitor without FDMS introduced absolute biases of 2.4 µg/m 3 (25%) to -2.3 µg/m 3 (-24%), respectively. Such errors are directly related to the unmeasured semivolatile mass and alter measures of spatiotemporal variability and homogeneity, all of which have implications for the regulatory and epidemiology communities concerned about PM 10-2.5 . Two monitoring sites operated by the state of Colorado were considered for inclusion in the CCRUSH acute health effects study, but concentrations were biased due to sampling with an FDMS-equipped PM 2.5 TEOM and PM 10 TEOM not corrected for semivolatile mass loss. A regression-based model was developed for removing the error in these measurements by estimating the semivolatile concentration of PM 2.5 from total PM 2.5 concentrations. By estimating nonvolatile PM 2.5 concentrations from this relationship, PM 10-2.5 was calculated as the difference between nonvolatile PM 10 and PM 2.5 concentrations.
Atmospheric Environment, 2012
h i g h l i g h t s < Sources of carbonaceous PM2.5 were resolved using Positive Matrix Factoriza... more h i g h l i g h t s < Sources of carbonaceous PM2.5 were resolved using Positive Matrix Factorization, PMF. < A 7 factor solution was obtained for a set of data pooled across the 4 urban sites. < Spatial variability of factor contributions was assessed. < A bootstrap technique was coupled with PMF model for modeling uncertainty assessment. < PMF solutions for site-specific datasets were compared with the pooled data solution.
Atmospheric Environment, 2013
This study presents source apportionment results for PM 2.5 from applying positive matrix factori... more This study presents source apportionment results for PM 2.5 from applying positive matrix factorization (PMF) to a 32-month series of daily PM 2.5 compositional data from Denver, CO, including concentrations of sulfate, nitrate, bulk elemental carbon (EC) and organic carbon (OC), and 51 organic molecular markers (OMMs). An optimum 8-factor solution was determined primarily based on the interpretability of the PMF results and rate of matching factors from bootstrapped PMF solutions with those from the base case solution. These eight factors were identified as inorganic ion, n-alkane, EC/sterane, light n-alkane/polycyclic aromatic hydrocarbon (PAH), medium alkane/alkanoic acid, PAH, winter/methoxyphenol and summer/odd n-alkane. The inorganic ion factor dominated the reconstructed PM 2.5 mass (sulfate + nitrate + EC + OC) in cold periods (daily average temperature < 10 °C; 43.7% of reconstructed PM 2.5 mass) whereas the summer/odd n-alkane factor dominated in hot periods (> 20 °C; 53.1%). The two factors had comparable relative contributions of 26.5% and 27.1% in warm periods with temperatures between 10 °C and 20 °C. Each of the seven factors resolved in a previous study (Dutton et al., 2010b) using a 1-year data set from the same location matches one factor from the current work based on comparing factor profiles. Six out of the seven matched pairs of factors are linked to similar source classes as suggested by the strong correlations between factor contributions (r = 0.89 − 0.98). Temperature-stratified source apportionment was conducted for three subsets of the data in the current study, corresponding to the cold, warm and hot periods mentioned above. The cold period (7-factor) solution exhibited a similar distribution of reconstructed PM 2.5 mass as the full data set solution. The factor contributions of the warm period (7-factor) solution were well correlated with those from the full data set solution (r = 0.76 − 0.99). However, the reconstructed PM 2.5 mass was distributed more to inorganic ion, n-alkane and medium alkane/alkanoic acid factors in the warm period solution than in the full data set solution. For the hot period (6-factor) solution, PM 2.5 mass distribution was quite different from that of the full data set solution, as illustrated by regression slopes as low as 0.2 and as high as 4.8 of each matched pair of factors across the two solutions.
Atmospheric Environment, 2012
h i g h l i g h t s < Concentrations of PM 2.5 associated carbonaceous species were measured from... more h i g h l i g h t s < Concentrations of PM 2.5 associated carbonaceous species were measured from 4 urban sites in Denver. < Spatial variability was assessed using the Pearson correlation coefficient (r) and coefficient of divergence (COD). < Near-highway sites exhibited higher concentrations of EC, OC, PAHs, and steranes than residential sites. < Large uncertainties associated with sampling and species quantification will bias the estimation of r and CODs. < CODs derived from co-located samples are useful points of reference to analyze spatial variability of PM 2.5 species.
Atmospheric Environment, 2002
... Steven G. Brown a , 1 , Pierre Herckes a , Lowell Ashbaugh b , Michael P. Hannigan a , 2 , So... more ... Steven G. Brown a , 1 , Pierre Herckes a , Lowell Ashbaugh b , Michael P. Hannigan a , 2 , Sonia M. Kreidenweis a and Jeffrey L ... The Big Bend Regional Aerosol and Visibility Observational (BRAVO) Study was conducted in Big Bend National Park, Texas, July through October ...
Cell, 2003
Efficient chemotaxis requires directional sensing and cell polarization. We describe a signaling ... more Efficient chemotaxis requires directional sensing and cell polarization. We describe a signaling mechanism involving G beta gamma, PAK-associated guanine nucleotide exchange factor (PIX alpha), Cdc42, and p21-activated kinase (PAK) 1. This pathway is utilized by chemoattractants to regulate directional sensing and directional migration of myeloid cells. Our results suggest that G beta gamma binds PAK1 and, via PAK-associated PIX alpha, activates Cdc42, which in turn activates PAK1. Thus, in this pathway, PAK1 is not only an effector for Cdc42, but it also functions as a scaffold protein required for Cdc42 activation. This G beta gamma-PAK1/PIX alpha/Cdc42 pathway is essential for the localization of F-actin formation to the leading edge, the exclusion of PTEN from the leading edge, directional sensing, and the persistent directional migration of chemotactic leukocytes. Although ligand-induced production of PIP(3) is not required for activation of this pathway, PIP(3) appears to localize the activation of Cdc42 by the pathway.
Environmental science & technology, 2007
Size distributions of particulate hopanes, steranes, and polycyclic aromatic hydrocarbons (PAHs) ... more Size distributions of particulate hopanes, steranes, and polycyclic aromatic hydrocarbons (PAHs) were measured in the exhaust from four heavy-duty diesel vehicles (HDDVs) operated under idle, creep, transient, and two highspeed driving modes. Particulate matter was collected using a chassis dynamometer and a dilution sampling system equipped with cascade impactors and filter samplers. Samples were extracted using organic solvents and analyzed using gas chromatography-mass spectrometry. Size distributions of hopanes and steranes were functions of engine load conditions and vehicle technology. Hopanes and steranes peaked in size ranges larger than 0.18 µm aerodynamic particle diameter under light load conditions and less than 0.10 µm aerodynamic particle diameter under heavier load conditions. The eight hopane size distributions emitted from newer technology (>1998) vehicles were unimodal while the four hopane size distributions emitted from older technology vehicles (<1992) were bimodal. Similar trends between older and newer vehicles were not observed for sterane size distributions. The PAH composition emitted from HDDVs was a function of driving cycle and vehicle technology. Light driving cycles produced quantifiable emissions of 3, 4, 5, and 6 ring PAHs (including coronene). Heavier driving cycles produced only the 3 and 4 ring PAHs in quantifiable amounts. PM1.8 and PM0.1 source profiles constructed using the relative abundance of hopanes and steranes to total organic carbon were functions of vehicle load condition. Increasing load reduced the relative abundance of motor oil tracers in the PM1.8 size fraction and increased the abundance of these tracers in the PM0.1 size fraction. The relative abundances of PAHs in the PM0.1 and PM1.8 size fractions emitted from the oldest vehicle tested (1985 HDDV) were significantly higher than for any other vehicle tested.
Environmental science & technology, 2012
To evaluate the utility and consistency of different speciation data sets in source apportionment... more To evaluate the utility and consistency of different speciation data sets in source apportionment of PM(2.5), positive matrix factorization (PMF) coupled with a bootstrap technique for uncertainty assessment was applied to four different 1-year data sets composed of bulk species, bulk species and water-soluble elements (WSE), bulk species and organic molecular markers (OMM), and all species. The five factors resolved by using only the bulk species best reproduced the observed concentrations of PM(2.5) components. Combining WSE with bulk species as PMF inputs also produced five factors. Three of them were linked to soil, road dust, and processed dust, and together contributed 26.0% of reconstructed PM(2.5) mass. A 7-factor PMF solution was identified using speciated OMM and bulk species. The EC/sterane and summertime/selective aliphatic factors had the highest contributions to EC (39.0%) and OC (53.8%), respectively. The nine factors resolved by including all species as input data are consistent with those from the previous two solutions (WSE and bulk species, OMM and bulk species) in both factor profiles and contributions (r = 0.88-1.00). The comparisons across different solutions indicate that the selection of input data set may depend on the PM components or sources of interest for specific source-oriented health study.
Environmental health perspectives, 2012
Neurotoxicology and teratology, 2013
We modeled binge patterns of high-dose toluene abuse during gestation in rats.We examined the beh... more We modeled binge patterns of high-dose toluene abuse during gestation in rats.We examined the behavioral and morphological impact of prenatal toluene in offspring.Toluene caused poor perinatal outcome, malformations and neonatal death.Results suggest that gestational toluene abuse may yield similar outcomes in humans.Binge Toluene Exposure in Pregnancy and Pre-weaning Developmental Consequences in Rats. Bowen, S.E. and Hannigan, J.H. The persistent rate of abuse of inhaled organic solvents, especially among women of child-bearing age, raises the risk for teratogenic effects of maternal toluene abuse. In this study, timed-pregnant Sprague Dawley rats were exposed from Gestation Day (GD) 8 to GD20 to 12,000 or 8000 parts per million (ppm) toluene, or 0 ppm (controls) for 30 min twice daily, 60 min total daily exposure. Pups were assessed from postnatal day (PN) 4 to PN21 using a developmental battery measuring growth (i.e., body weight), maturational milestones (e.g., eye opening & incisor eruption), and biobehavioral development (e.g., negative geotaxis & surface righting). Pups exposed in utero to 12,000 ppm or 8000 ppm toluene weighed significantly less than the non-exposed control pups beginning at PN4 and PN12 (respectively) until PN21. Toluene resulted in significant increases in an index of poor perinatal outcome, specifically a composite of malformations, defined “runting” and neonatal death. No significant delays were observed in reaching maturational milestones. The results reveal that brief, repeated, prenatal exposure to high concentrations of toluene can cause growth retardation and malformations in rats. A comparison of the present, conservative results with findings in previous studies implies that binge patterns of toluene exposure in pregnant rats modeling human solvent abuse can result in developmental and morphological deficits in offspring. These results do not exclude the possibility that maternal toxicity as well as teratogenic effects of toluene may contribute to outcomes. The results suggest that abuse of inhaled organic solvents like toluene may result in similar early developmental outcomes in humans.
Journal of dentistry, 2013
Best practice a b s t r a c t
International journal of nursing studies, 2013
This paper critically discusses the challenges mental health nurses face in trying to achieve a b... more This paper critically discusses the challenges mental health nurses face in trying to achieve a balance between fulfilling biomedical and social roles. We suggest that dilemmas exist for nurses in attempting to combine both approaches in their practice.
QJM : monthly journal of the Association of Physicians, 2013
Background: Gout and serum uric acid are associated with mortality but their simultaneous contrib... more Background: Gout and serum uric acid are associated with mortality but their simultaneous contributions have not been fully evaluated in the general population. Purpose: To explore the independent and conjoint relationships of gout and uric acid with mortality in the US population. Methods: Mortality risks of gout and serum uric acid were determined for 15 773 participants, aged 20 years or older, in the Third National Health and Nutrition Examination Survey by linking baseline information collected during 1988-1994 with mortality data up to 2006. Multivariable Cox proportional hazards regression determined adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for each exposure and all analyses were conducted in 2011 and 2012. Results: Compared with subjects without a history of gout, the multivariable HR for subjects with gout were 1.42 (CI 1.12-1.82) for total and 1.58 (CI 1.13-2.19) for cardiovascular mortality. Adjusted HRs per 59.5 mmol/l (1 mg/dl) increase in uric acid were 1.16 (CI 1.10-1.22) for total and cardiovascular mortality and this pattern was consistent across disease categories. In the conjoint analysis, the adjusted HRs for mortality in the highest two uric acid quartiles were 1.64 (CI 1.08-2.51) and 1.77 (CI 1.23-2.55), respectively, for subjects with gout, and were 1.09 (CI 0.87-1.37) and 1.37 (CI (1.11-1.70), respectively, for subjects without gout, compared with those without gout in the lowest quartile. A similar pattern emerged for cardiovascular mortality. Conclusions: Gout and serum uric acid independently associate with total and cardiovascular mortality. These risks increase with rising uric acid concentrations.
Journal of exposure science & environmental epidemiology, 2013
The US Environmental Protection Agency air pollution monitoring data have been a valuable resourc... more The US Environmental Protection Agency air pollution monitoring data have been a valuable resource commonly used for investigating the associations between short-term exposures to PM2.5 chemical components and human health. However, the temporally sparse sampling on every third or sixth day may affect health effect estimation. We examined the impact of non-daily monitoring data on health effect estimates using daily data from the Denver Aerosol Sources and Health (DASH) study. Daily concentrations of four PM2.5 chemical components (elemental and organic carbon, sulfate, and nitrate) and hospital admission counts from 2003 through 2007 were used. Three every-third-day time series were created from the daily DASH monitoring data, imitating the US Speciation Trend Network (STN) monitoring schedule. A fourth, partly irregular, every-third-day time series was created by matching existing sampling days at a nearby STN monitor. Relative risks (RRs) of hospital admissions for PM2.5 components at lags 0-3 were estimated for each data set, adjusting for temperature, relative humidity, longer term temporal trends, and day of week using generalized additive models, and compared across different sampling schedules. The estimated RRs varied somewhat between the non-daily and daily sampling schedules and between the four non-daily schedules, and in some instances could lead to different conclusions. It was not evident which features of the data or analysis were responsible for the variation in effect estimates, although seeing similar variability in resampled data sets with relaxation of the every-third-day constraint suggests that limited power may have had a role. The use of non-daily monitoring data can influence interpretation of estimated effects of PM2.5 components on hospital admissions in time-series studies.
The Science of the total environment, 2013
PM10–2.5 is more variable than PM2.5, acting as the major driver for PM10 extremes.Either PM10–2.... more PM10–2.5 is more variable than PM2.5, acting as the major driver for PM10 extremes.Either PM10–2.5 or PM2.5 can be the major driver for mean PM10 depending on site.Harvest and planting affect PM10–2.5, but do not have a strong influence on PM2.5.Year-specific data of agricultural activities are essential for emission estimates.PM10–2.5 and PM2.5 from traffic sources seem to be emitted by different processes.The characteristics of concentrations of PM10–2.5, PM2.5, and PM10 at 77 sites in the United States are evaluated. PM10 concentrations show strong spatial variability, with highest levels occurring in the southwestern United States, driven primarily by PM10–2.5. PM10–2.5 and PM2.5 concentrations show different spatial patterns. The highest concentrations of PM10–2.5 were observed at sites in the southwestern US, leading to the highest PM10 concentrations there. The PM2.5 concentrations are the major contributors to the average PM10 concentrations at many sites in the eastern United States. Poor correlations were generally found between PM10–2.5 and PM2.5, suggesting that PM10–2.5 and PM2.5 are generally influenced by different sources. PM10–2.5 is generally more variable than PM2.5 because PM10–2.5 has a higher deposition velocity and is primarily emitted from mechanical processes (e.g. agricultural harvest and construction) that are more influenced by factors including human operation and wind speed leading to a strong episodic nature. As a result of its high variability, PM10–2.5 acts as the major driver for PM10 extremes. PM10–2.5 is significantly correlated with PM10 at all investigated sites, with the average correlation value R2 = 0.79. Correlations of PM2.5 with PM10 (average of 0.37) are overall considerably lower than those between PM10–2.5 and PM10. Different seasonal, weekly, and diurnal patterns were observed between PM10–2.5 and PM2.5 at agricultural, on-road traffic, quarrying, airport, and marine sites. At investigated agricultural sites, while the concentrations of PM2.5 are higher in winter when there are few agricultural activities, PM10–2.5 concentrations are lower in winter months than in summer and autumn months, with highest levels corresponding to harvest and planting. The harvest and planting signatures were not observed in PM2.5 concentrations at any of these sites, suggesting that agricultural activities do not have a strong influence on PM2.5 concentrations.
Neurotoxicology and Teratology, 2007
Gestational Toluene Exposure Effects on Spontaneous and Amphetamine-Induced Locomotor Behavior in... more Gestational Toluene Exposure Effects on Spontaneous and Amphetamine-Induced Locomotor Behavior in Rats. Bowen, S.E., Mohammadi, M.H., Batis, J.C., and Hannigan, J.H. Neurotoxicology and Teratology, XX, 2006. The abuse of volatile organic solvents (inhalants) continues to be a major health concern throughout the world. Toluene, which is found in many products such as glues and household cleaners, is among the most commonly abused organic solvents. The neurobehavioral teratogenic sequelae of solvent abuse (i.e., repeated, brief inhalation exposures to very high concentrations of solvents) have not been examined thoroughly. In a preclinical model of inhalant abuse, timed-pregnant Sprague-Dawley rats were exposed to 0, 8000, or 12,000 parts per million (ppm) for 15 min twice daily from gestation day 8 (GD8) through GD20. In the first experiment, separate groups of offspring were observed individually in an open-field on postnatal day 22 (PN22), PN42 or PN63. In the second experiment, other offspring given identical prenatal toluene exposures were observed in an “open-field” following an acute i.p. injection of amphetamine (0, 0.56, 1.78 mg/kg) on PN28. Automated measurements of distance traveled and ambulatory time were recorded. Prenatal toluene exposure resulted in small alterations in spontaneous activity compared to non-exposed rats. Prenatal exposure to 12,000 ppm toluene resulted in significant hyposensitivity to the locomotor stimulatory effects of the amphetamine challenge in male but not female rats on PN28. The results demonstrate that prenatal exposure to abuse patterns of high concentrations of toluene through inhalation can alter spontaneous and amphetamine-induced locomotor behavior in rats. The expression of these effects also appears to depend upon the postnatal age of testing. These results imply that abuse of organic solvents during pregnancy in humans may also produce long-lasting effects on biobehavioral development.
Journal of Thoracic and Cardiovascular Surgery, 2011
Integrin-linked kinase, which is relevant to neoplastic transformation, is highly expressed in ma... more Integrin-linked kinase, which is relevant to neoplastic transformation, is highly expressed in malignant pleural mesothelioma. Recently, detection of integrin-linked kinase in serum of patients with ovarian cancer has been reported. This study asks whether integrin-linked kinase can also be detected in serum of patients with malignant pleural mesothelioma and whether serum level has diagnostic or prognostic relevance for that disease.A sandwich enzyme-linked immunosorbent assay was designed to detect integrin-linked kinase and applied to serum samples from 46 patients with malignant pleural mesothelioma, 98 patients with other malignant chest disease, and 23 patients with benign chest disease. Integrin-linked kinase serum concentration and clinical data were correlated statistically.Median serum integrin-linked kinase concentration was significantly higher in malignant pleural mesothelioma (8.89 ng/mL) than in other malignant chest disease (0.66 ng/mL) or benign chest disease (0.78 ng/mL, P < .001). There was no relevant correlation of serum integrin-linked kinase with cell lysis parameters (R2 < 0.1). Serum integrin-linked kinase concentration greater than 2.48 ng/mL had diagnostic sensitivity of 80%, specificity of 95%, positive predictive value of 85.7%, negative predictive value of 92.7%, and overall accuracy of 91% for distinction between malignant pleural mesothelioma and other diseases. Serum integrin-linked kinase concentration in malignant pleural mesothelioma was independent of histologic subtype or asbestos exposure. There was no statistically significant impact of serum integrin-linked kinase concentration on prognosis.Integrin-linked kinase can be detected in serum of patients with malignant pleural mesothelioma and may be a diagnostic marker for the disease.