Use of source apportionment model for designing acid deposition mitigating strategies in Massachusetts

The Commonwealth of Massachusetts promulgated an Act limiting S2 emissions from large sources that burn fuel at a rate greater than or equal to 100 million Btu (MBtu) of fuel input per hour. The Act requires that by 1995 the average emission rate at such facilities be less than or equal to 1.2 lb SO2 per MBtu fuel input. Because of their size, almost all power plants in Massachusetts could be subject to emission reductions. Since the average 1980-1982 annual emission rate of Massachusetts power plants was 1.84 lb S02/MBtu ("base case"), the Act requires the annual average emission rate of power plants to diminish by 35%. We use a source apportionment model to estimate the wet sulfate deposition to typical sensitive Massachusetts receptors from Massachusetts power plants, separately for the summer (April-September) and winter (October-March) half-years. We find that the summer wet deposition is about twice the winter deposition, although summer and winter SO2 emissions are approximately equal. Therefore, to reduce sulfate deposition, t is more effective to reduce emissions in the summer months rather than in winter. Using the seasonal source apportionment model we find that an annual wet deposition reduction equal to that resulting from the Act could be accomplished if only summer emission rates were reduced to 0.86 lb SO /MBtu, with winter emission rates remaining at 1.84 lb S02/MBtu. The resulging annual average emission rate is 1.35 lb SO /MBtu, 27% less than the base value. As 1980-1982 average annual emissions rom power plants amounted to 270,000 tons of SO annually, a summer emission control program would save about 21,000 tons of S emission reduction without sacrificing wet deposition protection. Te summer emission reduction could be acomplished by substituting lower sulfur content fuels, including natural gas, for higher sulfur content fuels.New England Power Company under the Electric Utility Program at the Energy Laborator

Ground-level ozone in eastern North America : its formation and transport

Ozone (Os), a natural component of the troposphere, is augmented by photochemical processes involving manmade emissions of nitrogen oxides (NOx) and volatile organic compounds (VOCs). Sufficiently high concentrations of ozone are detrimental to the respiratory system. Ozone exposure also reduces crop yields and damages forests. This study attempts to explain the underlying factors which contribute to observed ozone levels.Long range transport models of three species - NOx, VOCs and ozone - are developed for eastern North America. The seasonally averaged models include the essential physical and chemical processes in a relatively simple framework. NOx and VOCs are treated as primary species, i.e., they are modeled from their introduction into the atmosphere to their point of removal. Detailed emission inventories serve as input to the precursor models. Ozone is considered a secondary species because it is not directly emitted. Rather, its production is assumed to be a function of ambient NO, and VOCs levels.Measured concentrations, available for NO 2 and ozone, are compared with model predictions and aid in determining adjustable model parameters. Predicted NOx concentrations are consistent with rural observations but underestimate sites influenced by nearby sources at which the long range assumptions break down. Local models which properly treat proximate sources account for the discrepancy. The VOCs model, having no measurements for verification, adopts parameters consistent with the NOx model and known chemical properties. Both biogenic and manmade emissions contribute to ambient VOCs levels. Biogenic emissions are found to be more important over most of ENA; anthropogenic sources of VOCs are dominant only in urban areas.Consistent with empirical patterns, the ozone model predicts small regional gradients and hence a limited dependence on NOx and VOCs precursors. The natural background component is determined to be two-thirds of average ozone levels. Regional transport is significant; ozone lifetimes are estimated to be of the order of a day. The high background level and insensitivity to precursors suggests that significant reductions of average ozone concentrations will be difficult to achieve

Evidence for Domesticated and Wild Populations of Saccharomyces cerevisiae

Saccharomyces cerevisiae is predominantly found in association with human activities, particularly the production of alcoholic beverages. S. paradoxus, the closest known relative of S. cerevisiae, is commonly found on exudates and bark of deciduous trees and in associated soils. This has lead to the idea that S. cerevisiae is a domesticated species, specialized for the fermentation of alcoholic beverages, and isolates of S. cerevisiae from other sources simply represent migrants from these fermentations. We have surveyed DNA sequence diversity at five loci in 81 strains of S. cerevisiae that were isolated from a variety of human and natural fermentations as well as sources unrelated to alcoholic beverage production, such as tree exudates and immunocompromised patients. Diversity within vineyard strains and within saké strains is low, consistent with their status as domesticated stocks. The oldest lineages and the majority of variation are found in strains from sources unrelated to wine production. We propose a model whereby two specialized breeds of S. cerevisiae have been created, one for the production of grape wine and one for the production of saké wine. We estimate that these two breeds have remained isolated from one another for thousands of years, consistent with the earliest archeological evidence for winemaking. We conclude that although there are clearly strains of S. cerevisiae specialized for the production of alcoholic beverages, these have been derived from natural populations unassociated with alcoholic beverage production, rather than the opposite

Feasibility and cost of converting oil- and coal-fired utility boilers to intermittent use of natural gas

The continuous or intermittent use of natural gas in place of oil or coal in existing utility boilers would reduce emissions of sulfur and thereby the concentration of sulfate ions in precipitation. This report examines the technological feasibility and capital cost of retrofitting oil and coal fired utility boilers to burn intermittently natural gas and the parent fuel. Using extensive studies of the retrofitting of such boilers to burn synthetic gas of low to moderate heating value (LBG), it is found that natural gas closely simulates the combustion properties of LBG of medium heating value. Based upon this comparison, it is concluded that little or no modifications to the boiler are required to achieve the same boiler rating as when burning the original fuel, and that only a small efficiency penalty must be paid. Examination of the history of four eastern utility boiler conversions from oil to natural gas confirms these performance estimates, and shows that conversion costs for in-plant equipment are very small, less than 19 $(1985)/KW in all instances, while conversion times are less than one year (with little down time beyond that required for annual maintenance). Pipelining costs will vary with the local conditions.American Gas Associatio

Economics of seasonal gas substitution in coal- and oil-fired power plants

American Gas Associatio

Using whole-genome sequences of the LG/J and SM/J inbred mouse strains to prioritize quantitative trait genes and nucleotides

Background The laboratory mouse is the most commonly used model for studying variation in complex traits relevant to human disease. Here we present the whole-genome sequences of two inbred strains, LG/J and SM/J, which are frequently used to study variation in complex traits as diverse as aging, bone-growth, adiposity, maternal behavior, and methamphetamine sensitivity. Results We identified small nucleotide variants (SNVs) and structural variants (SVs) in the LG/J and SM/J strains relative to the reference genome and discovered novel variants in these two strains by comparing their sequences to other mouse genomes. We find that 39% of the LG/J and SM/J genomes are identical-by-descent (IBD). We characterized amino-acid changing mutations using three algorithms: LRT, PolyPhen-2 and SIFT. We also identified polymorphisms between LG/J and SM/J that fall in regulatory regions and highly informative transcription factor binding sites (TFBS). We intersected these functional predictions with quantitative trait loci (QTL) mapped in advanced intercrosses of these two strains. We find that QTL are both over-represented in non-IBD regions and highly enriched for variants predicted to have a functional impact. Variants in QTL associated with metabolic (231 QTL identified in an F16 generation) and developmental (41 QTL identified in an F34generation) traits were interrogated and we highlight candidate quantitative trait genes (QTG) and nucleotides (QTN) in a QTL on chr13 associated with variation in basal glucose levels and in a QTL on chr6 associated with variation in tibia length. Conclusions We show how integrating genomic sequence with QTL reduces the QTL search space and helps researchers prioritize candidate genes and nucleotides for experimental follow-up. Additionally, given the LG/J and SM/J phylogenetic context among inbred strains, these data contribute important information to the genomic landscape of the laboratory mouse

A Phosphomimetic Mutation Stabilizes SOD1 and Rescues Cell Viability in the Context of an ALS-Associated Mutation

The majority of amyotrophic lateral sclerosis (ALS)-related mutations in the enzyme Cu,Zn superoxide dismutase (SOD1), as well as a post-translational modification, glutathionylation, destabilize the protein and lead to a misfolded oligomer that is toxic to motor neurons. The biophysical role of another physiological SOD1 modification, T2-phosphorylation, has remained a mystery. Here, we find that a phosphomimetic mutation, T2D, thermodynamically stabilizes SOD1 even in the context of a strongly SOD1-destabilizing mutation, A4V, one of the most prevalent and aggressive ALS-associated mutations in North America. This stabilization protects against formation of toxic SOD oligomers and positively impacts motor neuron survival in cellular assays. We solve the crystal structure of T2D-SOD1 and explain its stabilization effect using discrete molecular dynamics (DMD) simulations. These findings imply that T2-phosphorylation may be a plausible innate cellular protection response against SOD1-induced cytotoxicity, and stabilizing the SOD1 native conformation might offer us viable pharmaceutical strategies against currently incurable ALS

Sigma factor n, liaison to an ntrC and rpoS dependent regulatory pathway controlling acid resistance and the LEE in enterohemorrhagic Escherichia coli

Enterohemorrhagic Escherichia coli (EHEC) is dependent on acid resistance for gastric passage and low oral infectious dose, and the locus of enterocyte effacement (LEE) for intestinal colonization. Mutation of rpoN, encoding sigma factor N (σ(N)), dramatically alters the growth-phase dependent regulation of both acid resistance and the LEE. This study reports on the determinants of σ(N)-directed acid resistance and LEE expression, and the underlying mechanism attributable to this phenotype. Glutamate-dependent acid resistance (GDAR) in TW14359ΔrpoN correlated with increased expression of the gadX-gadW regulatory circuit during exponential growth, whereas upregulation of arginine-dependent acid resistance (ADAR) genes adiA and adiC in TW14359ΔrpoN did not confer acid resistance by the ADAR mechanism. LEE regulatory (ler), structural (espA and cesT) and effector (tir) genes were downregulated in TW14359ΔrpoN, and mutation of rpoS encoding sigma factor 38 (σ(S)) in TW14359ΔrpoN restored acid resistance and LEE genes to WT levels. Stability, but not the absolute level, of σ(S) was increased in TW14359ΔrpoN; however, increased stability was not solely attributable to the GDAR and LEE expression phenotype. Complementation of TW14359ΔrpoN with a σ(N) allele that binds RNA polymerase (RNAP) but not DNA, did not restore WT levels of σ(S) stability, gadE, ler or GDAR, indicating a dependence on transcription from a σ(N) promoter(s) and not RNAP competition for the phenotype. Among a library of σ(N) enhancer binding protein mutants, only TW14359ΔntrC, inactivated for nitrogen regulatory protein NtrC, phenocopied TW14359ΔrpoN for σ(S) stability, GDAR and ler expression. The results of this study suggest that during exponential growth, NtrC-σ(N) regulate GDAR and LEE expression through downregulation of σ(S) at the post-translational level; likely by altering σ(S) stability or activity. The regulatory interplay between NtrC, other EBPs, and σ(N)-σ(S), represents a mechanism by which EHEC can coordinate GDAR, LEE expression and other cellular functions, with nitrogen availability and physiologic stimuli.Microbiology and Molecular Genetic

Real-Time On-Board Airborne Demonstration of High-Speed On-Board Data Processing for Science Instruments (HOPS)

The project called High-Speed On-Board Data Processing for Science Instruments (HOPS) has been funded by NASA Earth Science Technology Office (ESTO) Advanced Information Systems Technology (AIST) program since April, 2012. The HOPS team recently completed two flight campaigns during the summer of 2014 on two different aircrafts with two different science instruments. The first flight campaign was in July, 2014 based at NASA Langley Research Center (LaRC) in Hampton, VA on the NASA's HU-25 aircraft. The science instrument that flew with HOPS was Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) CarbonHawk Experiment Simulator (ACES) funded by NASA's Instrument Incubator Program (IIP). The second campaign was in August, 2014 based at NASA Armstrong Flight Research Center (AFRC) in Palmdale, CA on the NASA's DC-8 aircraft. HOPS flew with the Multifunctional Fiber Laser Lidar (MFLL) instrument developed by Excelis Inc. The goal of the campaigns was to perform an end-to-end demonstration of the capabilities of the HOPS prototype system (HOPS COTS) while running the most computationally intensive part of the ASCENDS algorithm real-time on-board. The comparison of the two flight campaigns and the results of the functionality tests of the HOPS COTS are presented in this paper