with Prof. Jon D. Levenson / Fulton Hall 511

No description available.

Conservation efforts to increase duck production have led the United States Fish and Wildlife Service to restore grasslands with multi-species (3-5) mixtures of cool season vegetation often termed dense nesting cover (DNC). The effectiveness of DNC to increase duck production has been variable, and maintenance of the cover type is expensive. In an effort to decrease the costs of maintaining DNC and support a more diverse community of wildlife, restoration of multi-species (16-32) plantings of native plants has been explored. Understanding the mechanisms of nest site selection for nesting ducks within these plantings is important in estimating the efficiency of this cover at providing duck nesting habitat and determining appropriate management techniques. I investigated the vegetation characteristics between the 2 aforementioned cover types in the prairie pothole region of North Dakota, USA to see if native plantings provide the same vegetative structure to nesting hens as DNC. I also determined the nest density and nest success of upland nesting waterfowl in the cover types to determine if restored native plantings are providing the same nesting opportunity as DNC. Within each cover type I identified vegetation characteristics at nest sites of the 5 most common nesting species and compared them to random locations and within species to identify species specific factors in nest site selection. I located 3,524 nests (1,313 in restored-native vegetation and 2,211 in DNC) of 8 species in 2010-11. Native plantings had an average of 6.17 (SE = 1.61) nests/ha while DNC had an average of 6.71 (0.96) nests/ha. Nest densities were not different between cover types for the 5 most common nesting species. In 2010, nest success differed between cover types with restored-native plantings having 48.36% (SE = 2.4) and DNC having 42.43% (2.1) success. In 2011, restored-native planting success dropped considerably to 13.92% (1.7) while DNC success was similar to 2010 at 37.10% (1.7) The variability in nest success appeared to be impacted by late season success, as native plantings had similar success early in the nesting season, but much lower success later in the nesting season in both years. Vegetation data indicated no structural difference between cover types in 2010; however, a difference was detected during the late sampling period in 2011, with native plantings having shorter vegetation at random locations than DNC during this sampling period. In general ducks selected nest sites with greater leaf litter and denser, taller cover compared to random sites, however, vegetation density and height selection varied among species. Gadwall and mallards selected the tallest, densest vegetation, with northern pintail, blue-winged teal, and northern shovelers selecting vegetation of intermediate height and density. My results indicate native plantings are able to support similar densities of nests, but have great variability in nest success from year to year. In years with low nest success, native plantings may create an ecological sink as hens were not able to identify low quality patches and nested in similar densities despite lower success.

A successful restoration of vision should allow the blind to look, to see and to understand. The engineering of a microelectronic vision prosthesis has come a long way over the last forty years, but the understanding of how the restored form of vision would be interpreted and functionally applied to everyday living has made little progress until recent times. Prosthetic vision is not what most people think it would be; it is a visual scene composed of relatively large, isolated, spots of light so-called "phosphenes", very much like a magnified pictorial print. This thesis dissertation seeks to obtain a complete survey of the visual description of phosphenes from the human trial reports in the literature, simulate it, obtain a measure of the functional capacity of such visual perception, and explain the measured performance against design aspects of phosphene presentation, human perception, cognition and behaviour. Specifically, "visual acuity" (VA) was assessed on normally sighted subjects (N=15) administered with "simulated prosthetic vision". VA is a functional measure of vision highly correlated to many daily activities. Aggregating the results from the study with the other VA studies in prosthetic vision, it is shown that in general, the density of the phosphene field determines the affordable VA; however, design aspects relating to the phosphene field lattice (0.03 10gMAR with the hexagonal lattice as opposed to a square lattice) and image processing routines (0.15 10gMAR at optimised settings) can be further fine-tuned to improve VA performance. Significant performance improvement also arose from learning (0.13 10gMAR over ten visitations) and visual scanning adaptation (0.20 10gMAR with a circular scanning strategy). Performance improvements are likely related to various preferences and perceptual preferences of the human visual system. A rehabilitation program targeting the appropriate behavioural adaptation coupled with image processing routine optimised for image comprehension should provide a vision prosthesis recipient with the best functional experience to restored vision.

No description available.

<p> Peatlands are an important component of the global carbon cycle, storing 23 g C m-2 yr-1 to comprise a global carbon pool of approximately 455 Pg. Peat drainage and harvesting results in removal of surface vegetation, thereby reducing gross photosynthesis to zero. Moreover, lowering the water table increases carbon oxidation. Consequently, peatland drainage and mining can reduce or eliminate the carbon sink function of the peatland. In the first part of this study, net ecosystem CO2 exchange was studied in a natural (NATURAL), two-year (YOUNG) and seven-year (OLD) post cutover peatland near Ste. Marguerite Marie, Quebec during the summer of 1998. Although the NATURAL site was a source of CO2 during the study season, CO2 emissions were 270 to 300% higher in the cutover sites (138, 363, and 399 g CO2-C m-2; NATURAL, YOUNG and OLD, respectively). Active restoration practices and natural re-vegetation of peatlands have the potential to return these ecosystems to net carbon sinks by increasing net ecosystem production (NEP) and therefore decreasing CO2 emissions to the atmosphere. Net ecosystem CO2 exchange in a natural (NATURAL) peatland and a partly restored peatland (REST) near Ste. Marguerite Marie, Quebec, was compared with a naturally re-vegetated peatland (RVEG) near Riviere-du-Loup, Quebec. Ecophysiological parameters indicate that the REST site was more than twice as productive as the natural LAWNS and three times as the RVEG site (GPmax=18.0, 8.3, and 6.5 g CO2 m-2 d-1, respectively). These results indicate that active restoration improves carbon sequestration over natural re-vegetation but that the net carbon sink function at both sites has not been restored. The presence of Sphagnum cover at the RVEG site resulted in a significant decrease in net ecosystem respiration (NER), indicating the potential for decreasing soil respiration at restored cutover sites through increasing the volumetric soil moisture content.</p> / Thesis / Master of Science (MSc)

ABSTRACT The effects of restoration on dissolved organic carbon (DOC) dynamics were examined at the Boi~-des-Bel peatland. This study included both laboratory measurements of DOC production by different peatland vegetative components and field measurements of DOC dynamics within a recently restored, a cutover and a natural peatland. Shrub and herbaceous plant material were found to be the most significant producers of DOC in the short term. Moss, peat and straw samples had a high potential to release DOC ;;ontinuously under warm, moist and aerobic conditions. On a short timescale, all components have the potential to release the three dissolved organic matter (DOM) fractions examined with humic acid (HA) most prominently being produced by shrubs and herbaceous plants and hydrophilic (HPI) and hydrophobic (HPO) fractions by mosses, peat and straw. Comparison of growing season results over three study years at the restored and cutover site indicated that DOC concentrations increased after restoration while DOC export decreased due to lowered runoff caused by the blockage of drainage ditches. Compared to the natural peatland, both the restored and the cutover site had a more humic DOM character. No difference could be found between the character of DOM released from the restored and cutover sites. The most active layer of DOM production was the top 75 em where the water iii table fluctuated during the season. Water storage units such as pools and ditches also play an important role in DOM export from the site. Spring snowmelt was found to be the most significant DOC export event of the study season in 2001, when export values were significantly larger than those measured during the growing season. Solubility of the different DOM fractions was the main controlling factor on the DOM character seen at the outflows. Storm events contributed significantly to the summer DOC output. DOC dynamics were affected by antecedent moisture conditions and differences emerged between the restored and cutover site during this period. The results of this study emphasize the importance of managing water table fluctuations and the restoration (reestablishment) of Sphagnum species in order to improve the retention of DOM within cutover peatlands. / Thesis / Master of Science (MS)

On July 8th, 1980, Raymond Carver wrote an impassioned letter to his editor, Gordon Lish, begging him to cancel the publication of what would soon become Carver’s minimalist masterpiece, What We Talk About When We Talk About Love. Carver argues in his letter that Lish’s heavily-edited versions of his original stories were bound to cause Carver's death. Despite his anxieties, Carver’s authorial demise didn’t come until 2009, 21 years following his physical death, when the unedited versions of the What We Talk About stories appeared in a posthumous collection called Beginners. Beginners excises Lish’s excisions, exposing a Raymond Carver at odds with his minimalist identity. The “restored” text also displaces Carver as the sole author of his work. We learn from Carver’s effacement that any cultural construction of an author is an erroneous effigy. Beginners exemplifies how textual restorations deflate cultural myths as they work with original texts to enrich our understanding

A preservação e a restauração de dentes severamente debilitados sem suporte dentinário no terço cervical do canal radicular é um procedimento difícil e de prognóstico duvidoso. Avaliou-se, por meio de ciclagem mecânica e compressão, a resistência à fratura e o padrão de fratura de raízes íntegras e fragilizadas, reconstruídas internamente com resina composta (Z 250) e pinos de fibra de vidro (Reforpost). Trinta caninos superiores humanos com anatomia radicular semelhante foram divididos em três grupos de acordo com a espessura do terço cervical: grupo I - raízes íntegras sem simulação de enfraquecimento e grupos II e III simularam raízes parcial e amplamente enfraquecidas. Estas foram reconstruídas através de preenchimento com resina composta fotopolimerizável por meio de um pino translumínico (Luminex). Todos os grupos tiveram coroas totais metálicas cimentadas sobre os núcleos em resina composta. Os pinos e coroas foram cimentados com cimento resinoso dual. Os corpos de prova foram submetidos à 250.000 ciclos numa freqüência de 2.6 Hz e carga de 3Kg. Posteriormente, os mesmos foram carregados numa máquina de ensaio universal à uma velocidade de carga de 0,5 mm/min até sua fratura. Em ambos os testes a angulação de carga foi de 135º em relação ao longo eixo do dente sobre a face palatina. Os valores de resistência à fratura foram: Grupo I-57,83Kgf; Grupo II-41,80 Kgf; Grupo III-41,93 Kgf. A análise de variância (ANOVA) (p<0,05) a um critério mostrou diferença estatisticamente significante entre os grupos. A comparação individual das médias revelou diferença somente entre o grupo I e os grupos II e III. O percentual de raízes com prognóstico favorável após a fratura foi: Grupo I -80%; Grupo II -40%; Grupo III -30%. Raízes fragilizadas foram menos resistentes à fratura e apresentaram menos fraturas favoráveis a reabilitação do que aa raízes íntegras. / The preservation and restoration of severely weakened pulpless teeth is a difficult and unpredictable procedure. This study evaluated the resistance to fracture and fracture patterns of weakened roots after restoration with glass fiber post, filling core of composite resin and total metallic crown submitted to cyclical and compressive load. Thirty upper canine teeth with similar dimensions were selected, being endodontic treatment performed. Samples were embedded and placed in a positioning jig. The teeth were divided into three groups in agreement with their cervical third thickness: group I (no weaken); Groups II (1.0mm) and III (0.5mm) simulated roots partial and largely weakened. The roots of groups II and III were reconstructed with composite resin through transparent plastic post (Luminex System-Dentatus). All groups received nickel-chrome cast metallic crowns. Both posts and crowns were cemented with a dual resinous cement. The specimens were impacted at 45 degrees to the long axis of the tooth with a force of 30 N at a frequency of 2.6 Hz for a total of 250.000 impacts. After were taken to the Universal Testing Machine for the fracture resistance test in a 135º and 0,5 mm/min speed. The fracture resistance values were: Group I -54,71 Kgf; Group II -40,04 Kgf; Group III -44,56 Kgf. Result show statistically significant differences in relation to the root conditions (ANOVA at one criterion p < 0,05). The samples with a favorable repair were: Group I -100%; Group II - 40%; Group III - 30%. The presence of more bulk of dentinal structure increased the resistance to fracture.

<p>Whether through sea level rise, farmland abandonment, or wetland restoration, agricultural soils in coastal areas will be inundated at increasing rates, renewing connections to sensitive surface waters and raising critical questions related to environmental tradeoffs. Wetland restoration in particular is often implemented not only to promote wildlife habitat, but also to improve water quality through nutrient removal, especially in agricultural catchments. The microbial process of denitrification is the central mechanism of nitrogen removal in wetlands and flooded soils, and can be seen as a potential environmental benefit of flooding agricultural lands. While denitrification undoubtedly can remove nitrogen from soil and surface water, higher soil moisture or flooding in wetland soils can also increase the production of greenhouse gases, specifically nitrous oxide and methane, representing a potential environmental tradeoff. Understanding the likely benefits of denitrification and the likely greenhouse gas costs of wetland restoration could help inform environmental policies concerning wetland restoration. </p> <p>Determining whether restored wetlands are larger sources of greenhouse gases compared to contrasting land use types (agriculture and forested wetlands) was the first goal of this dissertation (Chapter 2). We measured gas fluxes from soil and water to the atmosphere, and related environmental variables, in four sites over two years to estimate fluxes of the three major greenhouse gases. We found that carbon dioxide was the major contributor to the radiative balance across all sites, but that in the agricultural site and one of the forested wetland reference sites, nitrous oxide was the second most important contributor. Many studies have shown that methane is more important that nitrous oxide in most freshwater wetlands, as we found in the other forested wetland reference site and in flooded parts of the restored wetland. Overall, we did not find higher greenhouse gas fluxes in the restored wetland compared to agricultural soils or forested wetlands.</p> <p>The controls over nitrous oxide are especially complex, because it can be produced by two complementary processes, nitrification and denitrification, which generally occur under different conditions in the environment. In Chapter 3, we determined the soil and environmental factors that best predicted nitrous oxide fluxes for a subset of our data encompassing gas fluxes measured in November 2007. We found that soil temperature and soil carbon dioxide flux, along with ammonium availability and denitrification potential, were good predictors of nitrous oxide (adj R<super>2</super>=0.81). Although the nitrous oxide model did not perform as well when applied to data from another sampling period, we expect to further develop our modeling efforts to include possible non-linear temperature effects and a larger range of environmental conditions. </p> <p>In Chapter 4, we present results of a stable isotope tracer experiment to determine the relative contribution of nitrification and denitrification to nitrous oxide fluxes in these different land use types, and to determine the response of these processes to changing soil moisture. We added two forms of nitrogen-15 to intact soil cores to distinguish nitrification from denitrification, and subjected the cores to drainage or to a simulated rain event. We found that across the range of soil moisture, the fraction of nitrous oxide produced by denitrification did not change, but within each soil type there was a response to the simulated rain. In mineral soils, the nitrous oxide fraction increased with increasing soil moisture, with the highest mole fraction [N₂O/(N₂+N₂O)] in the agricultural soils, while in the organic soils there was no change or even a decrease. The fraction of nitrous oxide derived from coupled nitrification-denitrification increased with increasing soil moisture, and was much higher than that from denitrification alone in the more organic soils. This suggests that, in these saturated acid-organic soils, nitrification plays an important and underappreciated role in contributing to nitrous oxide fluxes from freshwater wetlands. The results from the laboratory experiment were consistent with patterns we saw in the field and help explain the differential contribution of nitrification and denitrification to nitrous oxide fluxes in different land use types in coastal plain wetlands of North Carolina. </p> <p>Overall, we found that both nitrification and denitrification contribute to nitrous oxide fluxes in coastal plain wetlands in North Carolina, and that nitrification is an especially important source in acid-organic soils under both field-moist and saturated conditions. Although freshwater wetlands, with an average nitrous oxide mole fraction of 0.08, are generally seen as being insignificant sources of nitrous oxide, our study sites ranged from 0.10 to 0.30, placing them closer to agricultural fields (0.38; Schlesinger 2009). Although the ecosystems in our study produced more nitrous oxide than expected for freshwater wetlands, we found no significant tradeoff between the local water quality benefits conferred by denitrification and the global greenhouse gas costs in the restored wetland. These results suggest that, from a nitrogen perspective, wetland restoration in coastal agricultural lands has a net environmental benefit.</p> / Dissertation