Comparisons of aging services in Canada and the United States reveal similarities and differences in the structure and function of the two systems. In both countries, adult day services (ADS) is an integral component in the array of services available to older adults. In this study, I compared structural characteristics of programs, participant characteristics, and examined the National Adult Day Services Association classification model of ADS in demographically similar areas of Canada and the United States. Directors of 47 ADS programs in demographically similar provinces and states in Atlantic Canada, Maine, and Vermont responded to a mailed survey. Adult day services programs in each province and state exhibited some unique structural and participant characteristics. Statistically significant differences emerged between ADS programs in the two countries on the following structural variables: town population, center affiliation, center location, levels of government support, participant fees, organizational structure, hours of operation, months of attendance, hours attended per day, service frequency, and service provision. Participant characteristics that significantly varied between the two countries involved educational level and functional characteristics. A minority of programs exhibited a match between participant needs and services provided. However, very few programs belonged to the most mismatched category of providing core services to intensive level participants. The findings of this study support the importance of individual programs providing services appropriate to meet the needs of participants rather than adhering to a predetermined model of care. / Ph. D.

Sustaining the global population depends upon modern agricultural practices reliant on large inputs of nitrogen (N) fertilizer, but export of excess N from agroecosystems has negative environmental consequences, such as accelerated eutrophication and associated water quality degradation. The challenges posed by diffuse and widespread nutrient pollution in agricultural drainage waters necessitate cost-effective, adaptable, and reliable solutions. In this context, enhanced denitrification approaches developed over the last several decades have produced denitrifying bioreactors that harness the ability of ubiquitous soil microorganisms to convert bioavailable N into inert N gas, thereby removing bioavailable N from an ecosystem. Denitrifying bioreactors are edge-of-field structures that consist of organic carbon substrate and support the activity of denitrifying soil bacteria that remove N from intercepted nutrient-enriched drainage waters. The potential to improve bioreactor performance and expand their application beyond the Midwest to the agriculturally significant Mid-Atlantic region was investigated with a three-pronged approach: 1) a pilot study investigating controls on N removal, 2) a laboratory study investigating controls on emission of greenhouse gases nitrous oxide (N2O), methane (CH4), and carbon dioxide (CO2), and 3) a field study of one of the first denitrifying bioreactors implemented in the Atlantic Coastal Plain. The pilot and laboratory studies tested the effect of amending woodchip bioreactors with biochar, an organic carbon pyrolysis product demonstrated to enhance microbial activity. The pilot-scale study provides evidence that either hardwood- of softwood-feedstock biochar may increase N removal in woodchip bioreactors, particularly under higher N loading. The results from the laboratory experiment suggest the particular pine-feedstock biochar tested may induce greater greenhouse gas emissions, particularly of the intermediate product of denitrification and potent GHG nitrous oxide. The field study evaluated performance of a biochar-amended woodchip bioreactor installed on a working farm. Two years of monitoring data demonstrated that the bioreactor successfully removed N from drainage waters, but at relatively low rates constrained by low N loading that occurred in the absence of fertilizer application during continuous soy cropping at the site (10.0 kg NO3--N ha-1 yr-1 or 4.86 g NO3- -N m-3 d-1 on the basis of bed volume reached the bioreactor.) Removal rates averaged 0.41 g m-3 d-1 (8.6% removal efficiency), significantly lower than average rates in systems receiving greater N loading in the Midwest, and more similar to installations in the Maryland Coastal Plain. Greenhouse gas fluxes were within the range reported for other bioreactors, and of the N removed an average of only 0.16% was emitted from the bed surface as N2O. This case study provides useful measurements of bioreactor operation under low N loading that informs the boundaries of bioreactor utility, and may have particular regional relevance. The pilot and field studies suggest that wood-based biochars may enhance N removal and may not produce problematic quantities of greenhouse gases, respectively. However, the laboratory study raises the need for caution when considering the costs and benefits amending woodchip bioreactors with biochar and accounting for the effect on greenhouse gas emissions in this calculation, because the tested pine biochar significantly increased these emissions. / PHD / Modern agricultural relies on nitrogen (N) fertilizer to produce enough food for the global population, but losses of excess N from farmland has negative environmental consequences. Even with advances in best practices to reduce the environmental impact of agriculture, such as nutrient management planning where the right fertilizer is applied at the right rate at the right time, crops cannot use fertilizer with perfect efficiency and a portion will be lost to the environment. A relatively new agricultural best management practice removes this excess N before it enters surface water bodies by intercepting drainage water with high N levels at the edge of the field, slowing it down, to give the tiny creatures living in the soil the chance to use this N as energy. These naturally occurring soil bacteria remove the N fertilizer from the water by transforming it into harmless N gas that makes up nearly 80% of the atmosphere. These denitrifying bioreactors, named after the microbial N removal mechanism, are becoming established management practices in the Midwest, but they have not yet been widely adopted in other agriculturally significant regions, such as the Mid-Atlantic. In an effort to design more effective and flexible bioreactors, the effect of amending woodchip bioreactors with a charcoal-like material previously shown to increase the activity N-removing bacteria was tested and found to modestly increase N removal with sufficiently high drainage water N concentrations. However, a laboratory test of the effect of biochar on production of a harmful intermediate product of denitrification, the potent greenhouse gas nitrous oxide, found higher emissions from the biochar treatments than the woodchips alone, suggesting the N removal benefits may v not outweigh the costs. To evaluate performance under field conditions, a biochar-amendment woodchip bioreactor was installed in the Virginia Coastal Plain, and monitored for two years. N removal was significantly lower than reported rates, but this was due to a relatively low amount of N in the drainage waters. However, measuring performance under sub-optimal conditions provides useful information for determining the limits to conditions for which bioreactors are useful.

Thesis advisor: Jeremy Shakun / Thesis advisor: Tony Wang / To better understand ice sheet and nutrient cycling dynamics in the North Atlantic, three geochemical paleo-proxies have been analyzed in Pleistocene marine sediments: cosmogenic nuclides (10Be and 26Al) in ice-rafted debris (IRD), 40Ar/39Ar in IRD, and foraminifera-bound nitrogen isotopes (FB-δ15N). For Chapter 1, we analyzed 10Be and 26Al concentrations in quartz separates of IRD from last-glacial North Atlantic sediments and used these data to constrain the history of Laurentide Ice Sheet (LIS) cover over Canada during the Pleistocene. While LIS history is well constrained since the Last Glacial Maximum (LGM) (~20,000 years ago), there is little evidence available from earlier times. 26Al/10Be ratios are depressed in these samples, the result of long-term decay under cover, which we suggest is best explained by a persistent LIS over much of the last million years. This finding implies that the LIS did not fully disappear during many Pleistocene interglacials, making the current ice-free Holocene interglacial relatively unique. For Chapter 2, we synthesized 3,762 40Ar/39Ar ages from North Atlantic IRD, including 670 new analyses. 595 of these single-grain analyses come from some of the same sample intervals as Chapter 1. These 40Ar/39Ar ages in IRD, a tracer of IRD provenance, clarify changes in North Atlantic ice sheet extent during the past few glacial cycles. Comparison of 40Ar/39Ar ages with hypothesized ice margins and cosmogenic nuclide data (from Chapter 1) aid in our interpretations. For last-glacial samples, results suggest ice sheets around the basin may have been in a retracted state during Marine Isotope Stage (MIS) 3 (~29-57 ka), an interval of debated ice extent for the LIS. Our synthesis also allows us to present the first complete records 40Ar/39Ar ages in IRD during Heinrich intervals – times when the LIS exhibited iceberg discharge events. These results support the suggestion made by previous work that Heinrich events 3 and 6 are anomalous relative to other intervals. 40Ar/39Ar analyses from earlier glacial periods – the first yet published – highlight that IRD provenance data may be reflecting iceberg survivability in addition to changes in ice extent. Lastly, analyzing cosmogenic nuclides and 40Ar/39Ar ages in IRD from the same sample intervals indicates that both proxies may be used to infer changes in ice sheet provenance; this is the first time cosmogenic nuclides in IRD have been considered in this way. For Chapter 3, we analyzed FB-δ15N at Site U1313 in North Atlantic samples during the Plio-Pleistocene to reconstruct marine nutrient cycling. In the North Atlantic, nutrient cycling is known to play an important role in regulating surface ocean productivity and CO2 drawdown via photosynthesis. We nevertheless lack a complete understanding of nutrient cycling evolution for the Plio-Pleistocene, during which Northern Hemisphere ice sheets and climate exhibited dramatic fluctuations. We find increasing FB-δ15N values at the transition from the Pliocene to the Pleistocene. Additionally, FB-δ15N values are generally higher during glacials compared to interglacials. We suggest these observations can best be explained by an expansion or increase of N2 fixation in the North Atlantic during warmer intervals (interglacials, Pliocene) and a retraction or decrease of N2 fixation during cold intervals (Pleistocene glacials). Considered alongside previously published paleo-proxy data from Site U1313 we suggest these changes in nutrient cycling reflect climate-driven migrations of the North Atlantic Current. In Chapter 4, I reflect upon how I have worked to integrate broader impacts into my Ph.D. work. Using a combined approach, I focused on fostering an inclusive environment within paleoclimate research spaces as well as engaging non-scientists in paleoclimate-and Earth science-related activities. These approaches ranged from K-12 partnership activities to mentoring students to more experimental avenues, such as a collaborative art project. I have evaluated the success of this work using a combination of quantitative metrics and subjective assessments. Participating in these efforts was also crucial for reminding me of the importance of making science accessible to everyone as well as for helping me hone my mentorship and science communication skills. / Thesis (PhD) — Boston College, 2024. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Earth and Environmental Sciences.

Thesis (M.S.)--Boston University / PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / 2999-01-01

Thesis (M.S.)--Boston University / PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / 2999-01-01

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Heinrich Events (HEs) define intervals of major ice rafting from the Laurentide Ice Sheet (LIS) into the North Atlantic during that last glacial period. The discovery of potential European-sourced precursors to HEs suggest that the smaller, but climactically sensitive, European ice sheets (EIS) may have played a role in the triggering of HEs and their impact on global climates. Environmental magnetism has proved itself to be a useful, rapid and non-destructive tool in the identification and quantification of provenance in sediments from various depositional environments. In this work, environmental magnetic analyses are applied to marine sediment records from the European margin of the NE Atlantic and known to contain ice-rafted debris (IRD) from both LIS and EIS sources. The primary aim in the work of this thesis is to evaluate the methodology as a means of distinguishing IRD provenance. From the data obtained here it is possible to identify several magnetic events that correspond to the HEs and other layers of detrital material and which correlate well to previous standard petrological analyses performed on the same core materials. Magnetic signatures differ within the HEs, suggesting a changing balance of input from multiple sources as opposed to a single LIS source. The data suggest a phasing of these compositional differences through individual HEs. The potential of using environmental magnetic techniques in the identification of IRD provenance within marine sediments is discussed, as is the significance of the observed provenance variations within the cores studied.

Salmonid alphaviruses (SAV) are a group of viruses that have recently emerged as a serious threat to the salmonid aquaculture industry in Europe. Over recent years, diseases caused by SAV have severely hampered the Scottish, Irish and Norwegian Atlantic salmon industry, and are considered to be among the major economically important viral diseases affecting the industry at present. Amongst the six subtypes characterised so far, Salmonid alphavirus 1 (SAV1) causes severe pathology in the heart, pancreas and the skeletal muscle of Atlantic salmon leading to death and growth retardation in the affected fish. The biochemical characteristics of the virus and the sequential pathology of the diseases caused by SAV have been described; however the mechanisms responsible for causing the disease and the host defence mechanisms against the virus are poorly defined. This thesis therefore examined the pathogenesis of SAV infection at the cellular and molecular level in vivo in salmon and in vitro in salmonid cells, with a special emphasis on host immune defence mechanisms against the virus. SAV was first isolated from Chinook salmon embryo-214 (CHSE-214) cells in 1995 in Ireland. Several cell lines have since been used to grow the virus. In the present study, three established salmonid cell lines, Chum salmon heart -1 (CHH-1), CHSE-214 and Salmon head kidney -1 (SHK-1) were evaluated for their ability to support the isolation of SAV-1 from infected fish tissue, with CHH-1 cells giving the fastest cytopathic effect (CPE) during primary isolation. The CPE appeared as localised cell-rounding on CHH-1 and CHSE-214 cells, although in SHK-1 cells, the cells were seen to slough off the monolayer relatively later than with the other two cell lines during the infection. The host response to SAV infection was evaluated by experimentally infecting Atlantic salmon parr using a cell culture-adapted virus isolate. A quantitative reverse transcription polymerase chain reaction (qRT-PCR) was developed to examine the virus load in the fish, from which it was found that the highest viral RNA copy number was detected at 5 day post infection (d.p.i), of the 90 day experimental infection period. Characteristic pathological lesions were only seen in the pancreas and the heart but not in the skeletal muscles of the infected fish. A gene expression study using qRT-PCR revealed the rapid induction of interferon (INF) and INF-associated genes in the head kidney of the infected fish compared to the control fish. The Mx protein was found to be highly expressed in the heart and the mucous membranes of infected fish by immunohistochemistry. Interestingly, the pathological changes that were seen occurred some time after the peak expression of genes associated with the INF-1-pathway. When the host-virus interaction of Atlantic salmon infected with SAV was examined using a microarray, a potent first line defence response was observed, together with the signatures of early activation of the adaptive immune response during the initial stages of the infection. Genes associated with transcription, translation and lipid metabolism were significantly differentially expressed in virus infected fish compared to control fish. A large array of antiviral genes was significantly expressed, amongst which were some of the genes also described in mammalian alphavirus infections. Genes associated with apoptosis and anti-apoptosis were also seen to be differentially regulated showing the complexity of the host-virus interaction. Collectively, all of these findings suggest that a non-specific antiviral immune response takes place providing rapid immune protection during the early stages of SAV infection in salmon. In the study on morphogenesis of SAV in salmonid cells using electron microscopy (EM), a rapid internalization of virus into the cells and generation of replication complexes using the secretory pathway of the cell, similar to mammalian alphavirus replication was observed. The mature viruses were released through surface projections, acquiring envelopes from the host cell membrane. From the ultrastructural studies of the salmonid cells infected with SAV, a progressive chromatin marginalisation and condensation could be seen, leading to cellular fragmentation, forming membrane bound apoptotic bodies, characteristic of progressive apoptosis. The activation of caspase-3 in the cytoplasm and genomic DNA damage were also seen in the infected fish cells, indicating that apoptosis is the main cause of cell death during SAV infection. The results of this study have increased our knowledge and understanding of the cellular and molecular mechanisms involved in the pathogenesis of SAV infection, emphasising the importance of the first line defence mechanisms against SAV infection in salmon. This has given an interesting insight into the host mechanisms used to combat the virus during infection, and will undoubtedly be useful for designing new vaccines and management strategies for prevention and control of this important disease

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