Evaluation of low wind modeling approaches for two tall-stack databases

The performance of the AERMOD air dispersion model under low wind speed conditions, especially for applications with only one level of meteorological data and no direct turbulence measurements or vertical temperature gradient observations, is the focus of this study. The analysis documented in this paper addresses evaluations for low wind conditions involving tall stack releases for which multiple years of concurrent emissions, meteorological data, and monitoring data are available. AERMOD was tested on two field-study databases involving several SO₂ monitors and hourly emissions data that had sub-hourly meteorological data (e.g., 10-min averages) available using several technical options: default mode, with various low wind speed beta options, and using the available sub-hourly meteorological data. These field study databases included (1) Mercer County, a North Dakota database featuring five SO₂ monitors within 10 km of the Dakota Gasification Company’s plant and the Antelope Valley Station power plant in an area of both flat and elevated terrain, and (2) a flat-terrain setting database with four SO₂ monitors within 6 km of the Gibson Generating Station in southwest Indiana. Both sites featured regionally representative 10-m meteorological databases, with no significant terrain obstacles between the meteorological site and the emission sources. The low wind beta options show improvement in model performance helping to reduce some of the overprediction biases currently present in AERMOD when run with regulatory default options. The overall findings with the low wind speed testing on these tall stack field-study databases indicate that AERMOD low wind speed options have a minor effect for flat terrain locations, but can have a significant effect for elevated terrain locations. The performance of AERMOD using low wind speed options leads to improved consistency of meteorological conditions associated with the highest observed and predicted concentration events. The available sub-hourly modeling results using the Sub-Hourly AERMOD Run Procedure (SHARP) are relatively unbiased and show that this alternative approach should be seriously considered to address situations dominated by low-wind meander conditions.

Implications: AERMOD was evaluated with two tall stack databases (in North Dakota and Indiana) in areas of both flat and elevated terrain. AERMOD cases included the regulatory default mode, low wind speed beta options, and use of the Sub-Hourly AERMOD Run Procedure (SHARP). The low wind beta options show improvement in model performance (especially in higher terrain areas), helping to reduce some of the overprediction biases currently present in regulatory default AERMOD. The SHARP results are relatively unbiased and show that this approach should be seriously considered to address situations dominated by low-wind meander conditions.     

Atmospheric H2O2 measurement: comparison of cold trap method with impinger bubbling method.

Collection of atmospheric H2O2 was performed by a cold trap method using dry ice-acetone as the refrigerant. The air was drawn by a pump into a glass gas trap immersed in the dry ice-acetone slush in a dewar flask at a flow rate of 2.5 l min-1 for approximately 2 h. Collection efficiency was > 99% and negligible interferences by O3, SO2 or organic matter with the collected H2O2 in the trap were observed. This method was compared with the air impinger bubbling method which has been previously described (Kok et al., 1978a, b, Envir. Sci. Technol. 12, 1072-1080). The measured total peroxide (H2O2 + organic peroxide) values in a series of aim samples collected by the impinger bubbling method (0.06-3.7 ppb) were always higher than those obtained by the cold trap method (0.02-1.2 ppb). Laboratory experiments suggest that the difference in values between the two methods probably results from the aqueous phase generation of H2O2 and organic peroxide in the impinger solution by a reaction of atmospheric O3 with olefinic and aromatic compounds. If these O3-organic compound reactions which occur in the impinger also occur in aqueous droplets in the atmosphere, the process could be very important for aqueous phase generation of H2O2 in clouds and rainwater.     

Modeling negative affectivity and job stress: a contingency‐based approach

Understanding the role of negative affectivity (NA) in relations between job stressors and resultant strains has been a major source of research interest in the organizational literature for almost two decades. In this study, we propose a contingency approach, whereby the role of NA depends on the nature of the strain construct under investigation. Specifically, we predicted that perceived job stressors would fully mediate the relationship between NA and turnover intentions, while job stressors would only partially mediate the relationship between NA and job and life satisfaction, and job stressors would be unrelated to depression once NA was taken into account. The relative fit of these four models is tested utilizing data from two divergent samples (sales representatives and managers) employing both self‐ and informant reports of strain measures where feasible. Hypotheses regarding the specified nature of the NA → stressor → strain relationship generally were supported and replicated across samples. In addition, an alternate model specifying that NA moderates the relationship between stressors and strains was not supported for any strain variable. Copyright © 2004 John Wiley & Sons, Ltd.     

Control of molecular weight distribution of the biopolymer pullulan produced byAureobasidium pullulans

The influence of carbon, nitrogen, and phosphate source, along with concentration, was determined for effect on the weight average molecular weight, molecular weight distribution, and yield of pullulan produced byAureobasidium pullulans NRRL-Y 6220. Batch systems, scale-up batch, and continuous fermentations of 1 L and 10 L were also evaluated as were processing variables, including solvents, and extraction conditions. Products with weight average molecular weight from 1.0 × 10⁵ to 4.0 × 10⁶ were produced in 100-g quantities by varying fermentation conditions such as constituents of the culture medium, pH, and length of incubation. Three sets of culture conditions were defined for the formation of low (<5.0×10⁵), medium (1.0–2.0×10⁶), and high (>2.0×10⁶) weight average molecular weight polymer. These defined molecular weight fractions of pullulan were used in further studies in producing films and fibers.     

Is “feeling good” good enough? Differentiating discrete positive emotions at work

Overwhelming evidence demonstrates the benefits of positive affect for various life and work outcomes. However, the relevant organizational research almost exclusively has focused on general positive affect, thereby implying that all positive affect has consistent and equal relationships with other work variables. The purposes of this theoretical paper are to review and highlight research from basic psychology demonstrating the unique nature and correlates of specific positive emotions and to translate those ideas and findings into the organizational context. Specifically, we discuss three discrete positive emotions—pride, interest, and gratitude—and offer propositions regarding their differential effects on relevant workplace outcomes and regarding the differential antecedents of them. Our hope is that this paper stimulates future research on this topic, and we offer specific research strategies and ideas to facilitate those endeavors. Copyright © 2014 John Wiley & Sons, Ltd.     

Prenatal diagnosis of congenital enzymopenic methaemoglobinaemia with mental retardation due to generalized cytochrome b5 reductase deficiency: First report of two cases

Prenatal diagnosis of congenital enzymopenic methaemoglobinaemia (CEM) with mental retardation was performed in two fetuses at risk for generalized NADH-cytochrome b₅ reductase deficiency. In the first case the enzyme activity of cultured amniotic cells was in the heterozygous to normal range. The mother delivered a normal baby with normal enzyme activity in cord blood cells. In the second case, the amniotic cells were almost completely enzyme deficient. The pregnancy was terminated, and the diagnosis of homozygous NADH-cytochrome b₅ reductase deficiency was confirmed in cord blood cells, in several different tissues and in cultured fibroblasts from the aborted fetus.