A comparison of integration methods for atmospheric transport-chemistry problems

This paper is devoted to the time integration of atmospheric transport-chemistry problems. Due to the large number of species and the 3D nature off-the-shelf solvers are not feasible. This has led to the use of special techniques. Most popular is operator splitting. This paper presents a comparison between standard operator splitting, source splitting and approximate matrix factorization. All methods under consideration are comparable in costs measured step wise. The comparison is directed at real-life problems. For that purpose a regional air pollution model is used

Exploration of the InfoMall Concept Building on the Electronic InfoMall

This document describes: the InfoMall concept; how it is employed by the Northeast Parallel Architectures center (NPAC) as a technology transfer program, how it could be used by Rome Laboratory and by the United States Air Force Materiel Command (US AFMC). A description of the “Electronic InfoMall” system built on the World Wide Web as a pilot project for Rome Laboratory is also given as well as some experiences building WWW systems for academic, commerce and industry. It should be emphasized that this document is primarily a description of the potential uses of the InfoMall concept and the human interactive processes involved in InfoMall and is not primarily about the HPCC technologies that make the InfoMall process work. These technologies are well described elsewhere although we summarize their main features in this document

Surface Water Quality Modelling Considering Riparian Wetlands

Riparian wetlands are believed to play an important role in mitigating non-point source pol- lution, acting as physical and biochemical buffers between diffuse pollution sources and receiving waters. Many studies examined riparian wetlands at the field scale, but there is a dearth of re- search at the watershed scale, particularly in the region of Southern Ontario, where agricultural land use predominates. This study examined the impacts of riparian wetlands on surface water quality at the water- shed scale. A field study was conducted on two sub-watersheds at the northern headwaters of the Canagagigue Creek within the Grand River Watershed in Southern Ontario. The two watersheds were similar in area and land use but with differing riparian wetland extent adjacent to the sub- watershed main channels. A two-year study was conducted examining the hydrology, hydraulics, water quality and nutrient fluxes from the two sub-basins. Water quality data were obtained at the outlet of each sub-basin during base-flow conditions and during 16 rainfall and snow melt runoff events. The hydrology was simulated using the WatFlood model and the water quality (nitrate and total suspended solids) was simulated using an enhancedWatFlood/AGNPS model that was modified to account for continuous simulation, in-stream contaminant fate/transport and riparian wetland influences. The hydraulics and hydrological characteristics of the two basins were distinct. The basin without riparian wetland protection (“West Basin”) exhibited ephemeral tendencies, going dry for several months in the summer, whereas the basin with extensive riparian wetland protection (“East Basin”) showed a persistent base-flow throughout the year with a consistently more rapid hydrological response. This study showed higher nutrient concentrations including nitrate, total nitrogen (TN), and total phosphorus (TP) in the West basin than the East basin, attributed to the lack of riparian wetland protection in the West sub-basin. Total Suspended Solids (TSS) concentration were higher in the east sub-basin than the west sub-basin attributed to differences in sediment grain size distributions and differences in local stream bed slope. Constituent loading estimates from the two sub-basins were conducted on an event-basis and on an average monthly load basis. This study showed that during events most constituents (Nitrate, TP, and TSS) were discharged in greater quantities from the East sub-basin than the West sub-basin for both rainfall and snowmelt events. Event-based TN loading was also higher for the East sub-basin but the difference was not statistically significant. Monthly average loading was significantly higher in the East sub-basin than the West sub-basin for Nitrate, TN and TSS. Monthly average loading was higher in the East basin than the West basin for TP as well, but the difference was not statistically significant. In spite of the generally higher nutrient concentrations in the West sub- basin, the east sub-basin exhibits higher loads due to the differing hydrological conditions in that basin. The persistent stream flow in the East basin continuously transports nutrients of a lower concentration than the West, but the consistent flow dominates the loading calculations resulting in a greater constituent mass transported. The modelling of sediment and nitrogen loading was conducted over the study period. Sedi- ment modelling results showed that the dominant process in the model was in-channel transport with the calibrated model showing very little sensitivity to overland transport parameters and riparian wetland retention. The ability to hydrologically model the basin accurately dictated the performance of the sediment transport model. Nitrogen modelling results demonstrated an ability to generally simulate the nitrogen profiles trends during storm events. However, the WatFlood groundwater storage model provided limitations in terms matching the nutrient concentration variability observed in the measured data. The processes that dominated model performance were fertilizer loading and nitrogen mineralization coefficients, with the riparian wetlands playing a small role in nitrogen removal in the calibrated model

Role of Oxidative Conditions on the Formation of Aerosol and Organic Nitrates from the Reactions of Monoterpenes with NO3 and OH radicals

Monoterpenes are widely emitted biogenic volatile organic compounds, which react quickly in the atmosphere and the oxidized products of which can partition into secondary organic aerosol (SOA). Understanding the types of products that are formed, how they might react in the particle-phase, and the effect of oxidative conditions on these factors is key for improving atmospheric models. This thesis presents three studies of monoterpene oxidation, with an emphasis on the role of organic nitrates in SOA. First, the products for &Delta;-3-carene are outlined in detail from NO3 radical oxidation in a regime where self- and cross-reactions of alkylperoxy radicals (RO2) are the primary fate of RO2&rsquo;s. These products include a small amount of an ROOR gas- and particle-phase dimer, but the majority of the products contributing to SOA are acetal and hemiacetal dimers. Then, this work is expanded to two other cyclic monoterpenes (&alpha;-pinene and limonene) and an acyclic ocimene. When compared to previous work with &alpha;-pinene, it is clear that acetal and hemiacetal dimers and trimers dominate the SOA of cyclic monoterpenes. This is not the case for linear ocimene, which shows a small degree of oligomerization in the particle-phase. Finally, these five monoterpenes are then oxidized by OH radicals in the presence of NOx, another way to form organic nitrates in the atmosphere. The SOA collected from these reactions have a similar degree of nitrate retention but little to no oligomerization. In addition, the SOA is shown to hydrolyze during analysis, which has implications for the atmospheric conditions under which the organic nitrates will last. Together, these works provide insight into monoterpene derived organic nitrates and their fates.</p

Key Topics on End-of-Life Care for African Americans

Racial classifications of human populations are politically and socially determined. There is no biological or genetic basis for these racial classifications. Health behaviors may be influenced by culture and poverty. Disparities in health outcomes, sometimes resulting in higher mortality rates for African-Americans appear to influence end of life decision-making attitudes and behaviors. To improve the quality of end of life care in African-American communities, health care professionals must better understand and work to eliminate disparities in health care, increase their own skills, knowledge and confidence in palliative and hospice care, and improve awareness of the benefits and values of hospice and palliative care in their patients and families

Aerospace medicine and biology: A continuing bibliography with indexes (supplement 405)

This bibliography lists 225 reports, articles and other documents introduced into the NASA Scientific and Technical Information System during Sep. 1995. Subject coverage includes: aerospace medicine and physiology, life support systems and man/system technology, protective clothing, exobiology and extraterrestrial life, planetary biology, and flight crew behavior and performance