Search

Search Results

• 3081. [Article] Overstory composition and stand structure shifts within inter-mixed ponderosa pine and lodgepole pine stands of the south-central Oregon pumice zone

  Ponderosa pine (Pinus ponderosa) and lodgepole pine (Pinus contorta var. murrayana) forests of south-central Oregon have been extensively researched over the last century. However, little information has ...

  Citation × Citation Citation Abstract Copy Title: Overstory composition and stand structure shifts within inter-mixed ponderosa pine and lodgepole pine stands of the south-central Oregon pumice zone Author: Shuffield, Chaylon D. Ponderosa pine (Pinus ponderosa) and lodgepole pine (Pinus contorta var. murrayana) forests of south-central Oregon have been extensively researched over the last century. However, little information has been reported on overstory composition and stand structure shifts associated with fire exclusion within inter-mixed ponderosa pine and lodgepole pine stands of the south-central Oregon pumice zone. In recent time, the lack of disturbance history and quantitative information needed to reconstruct historic stand conditions has become a growing concern for many ecologists. The need to collect quantitative information from remnant old-growth stands is imperative to improve restoration activities, incorporate stand-level diversity, identify the degree of successional departure, and to ensure valuable data is archived for future reference and ecological analysis. In Chapter 1, an exhaustive search for published information on early land-use practices specific to our study area was performed to: (1) identify the degree of Native American influence on vegetation; (2) identify direct and indirect Euro-American disturbances involving the loss of natural processes; and (3) establish a reference period for appropriate representation of historic conditions. In Chapter 2, remnant old-growth stands were analyzed using dendrochronological techniques and statistical comparisons to quantify: (1) shifts in overstory composition and stand structure; (2) growth and development of ponderosa pine and lodgepole pine across time; and to (3) characterize the influence of climate and fire on species recruitment. Our analysis indicated successional trajectory shifts occurred shortly after the loss of Native American influence beginning around 1850 and associated affects of intensive grazing following 1880. Age reconstruction displayed an exponential pattern of recruitment between 1880 and 1950. Since 1850, our analysis revealed a reduction in average tree basal area growth and height development of understory ponderosa pine and lodgepole pine. Ponderosa pine greater than 150 years old accounted for less than 5.0% of the total contemporary density, but composed 45.0% of the total basal area. Lodgepole pine greater than 100 years old accounted for approximately 3.0% of the total contemporary density and composed 12.8% of the total basal area. Stand density for our study area averaged 25.3 trees per hectare for ponderosa pine greater than 53.3 centimeters diameter at 1.4 meters. We report low levels of lodgepole pine recruitment (2/hectare/decade) prior to 1880 and suggest the long-term development of less fire-resistant lodgepole pine has been favored since fire exclusion. Furthermore, contemporary settings support conditions associated to atypical mountain pine beetle outbreaks and fire behavior known to cause mortality of large diameter ponderosa pine. Restoration of remnant inter-mixed stands requires the aggressive removal of lodgepole pine and re-introduction of fire to provide long-term sustainability of ecosystem health and preservation of large diameter ponderosa pine. Title: Overstory composition and stand structure shifts within inter-mixed ponderosa pine and lodgepole pine stands of the south-central Oregon pumice zone Author: Shuffield, Chaylon D. Ponderosa pine (Pinus ponderosa) and lodgepole pine (Pinus contorta var. murrayana) forests of south-central Oregon have been extensively researched over the last century. However, little information has been reported on overstory composition and stand structure shifts associated with fire exclusion within inter-mixed ponderosa pine and lodgepole pine stands of the south-central Oregon pumice zone. In recent time, the lack of disturbance history and quantitative information needed to reconstruct historic stand conditions has become a growing concern for many ecologists. The need to collect quantitative information from remnant old-growth stands is imperative to improve restoration activities, incorporate stand-level diversity, identify the degree of successional departure, and to ensure valuable data is archived for future reference and ecological analysis. In Chapter 1, an exhaustive search for published information on early land-use practices specific to our study area was performed to: (1) identify the degree of Native American influence on vegetation; (2) identify direct and indirect Euro-American disturbances involving the loss of natural processes; and (3) establish a reference period for appropriate representation of historic conditions. In Chapter 2, remnant old-growth stands were analyzed using dendrochronological techniques and statistical comparisons to quantify: (1) shifts in overstory composition and stand structure; (2) growth and development of ponderosa pine and lodgepole pine across time; and to (3) characterize the influence of climate and fire on species recruitment. Our analysis indicated successional trajectory shifts occurred shortly after the loss of Native American influence beginning around 1850 and associated affects of intensive grazing following 1880. Age reconstruction displayed an exponential pattern of recruitment between 1880 and 1950. Since 1850, our analysis revealed a reduction in average tree basal area growth and height development of understory ponderosa pine and lodgepole pine. Ponderosa pine greater than 150 years old accounted for less than 5.0% of the total contemporary density, but composed 45.0% of the total basal area. Lodgepole pine greater than 100 years old accounted for approximately 3.0% of the total contemporary density and composed 12.8% of the total basal area. Stand density for our study area averaged 25.3 trees per hectare for ponderosa pine greater than 53.3 centimeters diameter at 1.4 meters. We report low levels of lodgepole pine recruitment (2/hectare/decade) prior to 1880 and suggest the long-term development of less fire-resistant lodgepole pine has been favored since fire exclusion. Furthermore, contemporary settings support conditions associated to atypical mountain pine beetle outbreaks and fire behavior known to cause mortality of large diameter ponderosa pine. Restoration of remnant inter-mixed stands requires the aggressive removal of lodgepole pine and re-introduction of fire to provide long-term sustainability of ecosystem health and preservation of large diameter ponderosa pine. Close

• 3082. [Article] Crustal shortening and tectonic evolution of the Salt Range in Northwest Himalaya, Pakistan

  The Salt Range is clearly the active participant in the scenario of the progressive southward migration of the Himalayan thrust front. It extends approximately 180 km ENE along strike and is underlain ...

  Citation × Citation Citation Abstract Copy Title: Crustal shortening and tectonic evolution of the Salt Range in Northwest Himalaya, Pakistan Author: Qayyum, Mazhar The Salt Range is clearly the active participant in the scenario of the progressive southward migration of the Himalayan thrust front. It extends approximately 180 km ENE along strike and is underlain by salt. This is manifested by its very narrow (<1°) cross-sectional taper and great (150 km) width. Integration of approximately 450 km of seismic reflection data with available surface geologic, magnetostratigraphic, and exploration well data help in delineating different tectonic features in the Salt Range. These studies reveal a concealed duplex structure under the roof sequence, help to determine the footwall and hangingwall geometries of the leading edge at different successive evolutionary stages, estimate the lateral extent of a basement normal fault, constrain the ages of different structural features, and define lateral variations in the deformational style within the leading edge. The above mentioned features have been synthesized to document an out-of-sequence evolutionary model of the Salt Range. The newly recognized, concealed duplex structure extends more than 40 km along the strike and gradually progrades southward along a décollement that first ramps within the Salt Range Formation and then across the platform sequence and follows the shaley horizons of overlying Murree Formation near the contact. This duplex structure is terminated along the two lateral ramps in the east and west. The northern ramp in the footwall of the roof sequence is localized by a basement normal fault in the central Salt Range, and changes its position and characteristics in the eastern and western Salt Range. In the western Salt Range, it is located 15 km farther south and is entirely within the sedimentary sequence. These two segments are linked by a lateral ramp that developed over the western culmination wall of the lateral ramp associated with the underlying duplex structure. In the eastern Salt Range, however, the northern ramp first continues within the sedimentary sequence beyond the end of the basement normal fault and farther east it changes into an oblique ramp. This oblique ramp is truncated by another N-S trending lateral ramp farther to the east. The monoclinal structure of the Chambal Ridge marks the southernmost extension of this lateral ramp. Along this lateral ramp the roof sequence steps down and joins the basal décollement. Due to the down stepping of the roof sequence the structural style also changes from fault-bend fold to fault propagated fold geometry. Because in fault-bend fold geometry the major component of shortening was accommodated across the northern ramp, very little shortening occurred within the roof sequence. In contrast, all the shortening in the east has been distributed over a region in a prograde fashion. Therefore, the thrust wedge is internally deformed into a fault propagated fold geometry to provide a surface topographic slope necessary to maintain a critical taper. The concealed duplex structure is the earliest structure of the Himalayan thrust front that was formed during 9-7 m.y., and further suggests that out of sequence thrusting has occurred over a region of 150 km during the past 9 m.y. Due to the development of a basement normal fault at 7 m.y., the thrust acquired a high friction front and was unable to move forward. Crustal shortening was then taken up by the Main Boundary Thrust zone in the north, which was quite active during this time. Between 5-6 m.y., the thrust wedge started to ramp over the basement normal fault, facilitated by the development of a thick salt pad on the down-thrown side, during 7-6 m.y. The newly built topography due to the ramping of the thrust wedge resisted the southwards propagation of the roof sequence and caused further out-of-sequence thrusting in the north but was not sufficient to stop its southward progradation. It was followed by the major horizontal translation of the roof sequence over the roof sequence flat. This study also suggests that 13° counter clockwise rotation has occurred along the northern ramp and the concealed duplex structure. Recognition of the concealed duplex structure and better understanding of the footwall geometry of the roof sequence also generates new prospects of oil exploration in the Salt Range. Title: Crustal shortening and tectonic evolution of the Salt Range in Northwest Himalaya, Pakistan Author: Qayyum, Mazhar The Salt Range is clearly the active participant in the scenario of the progressive southward migration of the Himalayan thrust front. It extends approximately 180 km ENE along strike and is underlain by salt. This is manifested by its very narrow (<1°) cross-sectional taper and great (150 km) width. Integration of approximately 450 km of seismic reflection data with available surface geologic, magnetostratigraphic, and exploration well data help in delineating different tectonic features in the Salt Range. These studies reveal a concealed duplex structure under the roof sequence, help to determine the footwall and hangingwall geometries of the leading edge at different successive evolutionary stages, estimate the lateral extent of a basement normal fault, constrain the ages of different structural features, and define lateral variations in the deformational style within the leading edge. The above mentioned features have been synthesized to document an out-of-sequence evolutionary model of the Salt Range. The newly recognized, concealed duplex structure extends more than 40 km along the strike and gradually progrades southward along a décollement that first ramps within the Salt Range Formation and then across the platform sequence and follows the shaley horizons of overlying Murree Formation near the contact. This duplex structure is terminated along the two lateral ramps in the east and west. The northern ramp in the footwall of the roof sequence is localized by a basement normal fault in the central Salt Range, and changes its position and characteristics in the eastern and western Salt Range. In the western Salt Range, it is located 15 km farther south and is entirely within the sedimentary sequence. These two segments are linked by a lateral ramp that developed over the western culmination wall of the lateral ramp associated with the underlying duplex structure. In the eastern Salt Range, however, the northern ramp first continues within the sedimentary sequence beyond the end of the basement normal fault and farther east it changes into an oblique ramp. This oblique ramp is truncated by another N-S trending lateral ramp farther to the east. The monoclinal structure of the Chambal Ridge marks the southernmost extension of this lateral ramp. Along this lateral ramp the roof sequence steps down and joins the basal décollement. Due to the down stepping of the roof sequence the structural style also changes from fault-bend fold to fault propagated fold geometry. Because in fault-bend fold geometry the major component of shortening was accommodated across the northern ramp, very little shortening occurred within the roof sequence. In contrast, all the shortening in the east has been distributed over a region in a prograde fashion. Therefore, the thrust wedge is internally deformed into a fault propagated fold geometry to provide a surface topographic slope necessary to maintain a critical taper. The concealed duplex structure is the earliest structure of the Himalayan thrust front that was formed during 9-7 m.y., and further suggests that out of sequence thrusting has occurred over a region of 150 km during the past 9 m.y. Due to the development of a basement normal fault at 7 m.y., the thrust acquired a high friction front and was unable to move forward. Crustal shortening was then taken up by the Main Boundary Thrust zone in the north, which was quite active during this time. Between 5-6 m.y., the thrust wedge started to ramp over the basement normal fault, facilitated by the development of a thick salt pad on the down-thrown side, during 7-6 m.y. The newly built topography due to the ramping of the thrust wedge resisted the southwards propagation of the roof sequence and caused further out-of-sequence thrusting in the north but was not sufficient to stop its southward progradation. It was followed by the major horizontal translation of the roof sequence over the roof sequence flat. This study also suggests that 13° counter clockwise rotation has occurred along the northern ramp and the concealed duplex structure. Recognition of the concealed duplex structure and better understanding of the footwall geometry of the roof sequence also generates new prospects of oil exploration in the Salt Range. Close

• 3083. [Article] Biomass and community structure of sporocarps formed by hypogeous ectomycorrhizal fungi within selected forest habitats of the H. J. Andrews Experimental Forest, Oregon

  This study characterizes the production of hypogeous sporocarps (broadly referred to as truffles) by ectomycorrhizal fungi within Douglas-fir dominated forests that are considered typical of those found ...

  Citation × Citation Citation Abstract Copy Title: Biomass and community structure of sporocarps formed by hypogeous ectomycorrhizal fungi within selected forest habitats of the H. J. Andrews Experimental Forest, Oregon Author: Luoma, Daniel L. This study characterizes the production of hypogeous sporocarps (broadly referred to as truffles) by ectomycorrhizal fungi within Douglas-fir dominated forests that are considered typical of those found on the west slopes of the central Cascade mountains in Oregon. Three aspects of sporocarp production are addressed: 1) the distribution of total biomass and biomass of each species by season and habitat, 2) analysis of sporocarp biomass from the perspective of community structure, and 3) correlation of biomass production with sporocarp number and selected forest floor parameters. Sporocarps with an equivalent dry standing biomass of 1.3 kg/ha were harvested from ten Douglas-fir stands in and near the H. J. Andrews Experimental forest. The maximum single stand sample biomass was equivalent to 9.9 kg/ha. Forty-seven species of hypogeous fungi were recorded during the study (although some collections are of uncertain taxonomic affinity and some taxa are of uncertain status). Fourteen species account for 93% of the total biomass. Five species account for 73% of the biomass (Elaphomyces granulatus, Gautieria monticola, Hysterangium coriaceum, Leucogaster rubescens, and Rhizopogon parksii). Individual species showed strong differential trends in seasonal production of sporocarp biomass, with spring and summer production being greater than fall in contrast to fall fruiting epigeous species. Many species showed differences in sporocarp production by habitat. Sporocarp production was evaluated in five Douglas-fir habitats, (wet old-growth, mesic old-growth, dry old-growth, mesic mature, and mesic young). The mesic mature forest habitat has the highest standing biomass value (2.2 kg/ha) of all the habitats. The dry old-growth forest habitat had the lowest (0.7 kg/ha). Analysis of the distribution of sample values indicates that samples of small total area overestimate biomass because of the strong skewing towards high values. Interspersion of the largest practical number of quadrats is required to reduce overestimation of standing biomass (expressed on a kg/ha basis) when localized concentrations of biomass are included in samples. Vegetation studies have shown that, for vascular plants, similar species combinations recur under similar habitat conditions. Also, species abundance and composition change more or less continuously over the landscape. This study found communities of hypogeous ectomycorrhizal fungi to be co-extensive with associated vascular plant communities and sensitive to subtle variations in habitats spanning wet-to-dry and young-to-old gradients. A profound dichotomy in seasonal fruiting pattern between spring and fall precludes the use of single season sampling to reveal fungal community structure. Furthermore, yearly variation in weather patterns causes variation in sporocarp biomass production that tends to obscure community structure responses to environmental gradients. When fungal data collected over a number of years from a stand are integrated, subsequent classification and ordination closely reflect the vascular plant classification and subtle responses to a moisture gradient. A fungal community guild structure was delineated that reflected the subtle variation in the studied habitats. The guild of hypogeous ectomycorrhizal has Rhizopogon parksii as the subterranean dominant counterpart to Pseudotsuga menziesii with Gautieria monticola nearly as wide spread and abundant. Changes in fungal community structure along the stand age gradient are noted, but the limited amount of replication in the present study makes this interpretation tentative. Within three old-growth stands ranging from wet to dry, sporocarp biomass and numbers of hypogeous sporocarps were assessed in relation to each other, coarse woody debris, forest floor litter, and other selected forest floor parameters by use of regression models. Significant regressions between forest floor parameters are also examined. Transformation of data values improved the normality of the distributions for most parameters. The regression of sporocarp biomass and number of sporocarps is significant, however, it is not a strong relationship and the use of numbers of sporocarps as a substitute for biomass is not recommended. The correlation between sporocarp biomass and forest floor depth was significant in the mesic old-growth stand only. Significant regression relationships between parameters are highly individualistic within each stand. Over all stands, a slight tendency for forest floor depth to increase with coarse woody debris cover was noted. Regression analysis may have been hampered by the old-growth status of all stands. Perhaps, due to centuries of development without catastrophic disturbance, within-stand variation in the chosen parameters has been reduced to the point that trends in the relations between selected parameters are difficult to detect. In designing future research, it would be advisable to include stands varying considerably in old-growth characteristics and to assess the degree to which "carry over" of characteristics into second growth stands affects sporocarp production. Title: Biomass and community structure of sporocarps formed by hypogeous ectomycorrhizal fungi within selected forest habitats of the H. J. Andrews Experimental Forest, Oregon Author: Luoma, Daniel L. This study characterizes the production of hypogeous sporocarps (broadly referred to as truffles) by ectomycorrhizal fungi within Douglas-fir dominated forests that are considered typical of those found on the west slopes of the central Cascade mountains in Oregon. Three aspects of sporocarp production are addressed: 1) the distribution of total biomass and biomass of each species by season and habitat, 2) analysis of sporocarp biomass from the perspective of community structure, and 3) correlation of biomass production with sporocarp number and selected forest floor parameters. Sporocarps with an equivalent dry standing biomass of 1.3 kg/ha were harvested from ten Douglas-fir stands in and near the H. J. Andrews Experimental forest. The maximum single stand sample biomass was equivalent to 9.9 kg/ha. Forty-seven species of hypogeous fungi were recorded during the study (although some collections are of uncertain taxonomic affinity and some taxa are of uncertain status). Fourteen species account for 93% of the total biomass. Five species account for 73% of the biomass (Elaphomyces granulatus, Gautieria monticola, Hysterangium coriaceum, Leucogaster rubescens, and Rhizopogon parksii). Individual species showed strong differential trends in seasonal production of sporocarp biomass, with spring and summer production being greater than fall in contrast to fall fruiting epigeous species. Many species showed differences in sporocarp production by habitat. Sporocarp production was evaluated in five Douglas-fir habitats, (wet old-growth, mesic old-growth, dry old-growth, mesic mature, and mesic young). The mesic mature forest habitat has the highest standing biomass value (2.2 kg/ha) of all the habitats. The dry old-growth forest habitat had the lowest (0.7 kg/ha). Analysis of the distribution of sample values indicates that samples of small total area overestimate biomass because of the strong skewing towards high values. Interspersion of the largest practical number of quadrats is required to reduce overestimation of standing biomass (expressed on a kg/ha basis) when localized concentrations of biomass are included in samples. Vegetation studies have shown that, for vascular plants, similar species combinations recur under similar habitat conditions. Also, species abundance and composition change more or less continuously over the landscape. This study found communities of hypogeous ectomycorrhizal fungi to be co-extensive with associated vascular plant communities and sensitive to subtle variations in habitats spanning wet-to-dry and young-to-old gradients. A profound dichotomy in seasonal fruiting pattern between spring and fall precludes the use of single season sampling to reveal fungal community structure. Furthermore, yearly variation in weather patterns causes variation in sporocarp biomass production that tends to obscure community structure responses to environmental gradients. When fungal data collected over a number of years from a stand are integrated, subsequent classification and ordination closely reflect the vascular plant classification and subtle responses to a moisture gradient. A fungal community guild structure was delineated that reflected the subtle variation in the studied habitats. The guild of hypogeous ectomycorrhizal has Rhizopogon parksii as the subterranean dominant counterpart to Pseudotsuga menziesii with Gautieria monticola nearly as wide spread and abundant. Changes in fungal community structure along the stand age gradient are noted, but the limited amount of replication in the present study makes this interpretation tentative. Within three old-growth stands ranging from wet to dry, sporocarp biomass and numbers of hypogeous sporocarps were assessed in relation to each other, coarse woody debris, forest floor litter, and other selected forest floor parameters by use of regression models. Significant regressions between forest floor parameters are also examined. Transformation of data values improved the normality of the distributions for most parameters. The regression of sporocarp biomass and number of sporocarps is significant, however, it is not a strong relationship and the use of numbers of sporocarps as a substitute for biomass is not recommended. The correlation between sporocarp biomass and forest floor depth was significant in the mesic old-growth stand only. Significant regression relationships between parameters are highly individualistic within each stand. Over all stands, a slight tendency for forest floor depth to increase with coarse woody debris cover was noted. Regression analysis may have been hampered by the old-growth status of all stands. Perhaps, due to centuries of development without catastrophic disturbance, within-stand variation in the chosen parameters has been reduced to the point that trends in the relations between selected parameters are difficult to detect. In designing future research, it would be advisable to include stands varying considerably in old-growth characteristics and to assess the degree to which "carry over" of characteristics into second growth stands affects sporocarp production. Close

• 3084. [Article] Crown structure, stand dynamics, and production ecology of two species mixtures in the central Oregon Cascades

  Knowledge of stand structure, stand dynamics, and production ecology of species mixtures lags well behind that of single-species, even-aged stands. Two mixed-species spacing trials in central Oregon allowed ...

  Citation × Citation Citation Abstract Copy Title: Crown structure, stand dynamics, and production ecology of two species mixtures in the central Oregon Cascades Author: Garber, Sean M. Knowledge of stand structure, stand dynamics, and production ecology of species mixtures lags well behind that of single-species, even-aged stands. Two mixed-species spacing trials in central Oregon allowed investigation of mixed-species dynamics in a controlled experimental setting. The first site, Pringle Butte, is a mixture of ponderosa pine (Pinus ponderosa Dougl. ex Laws.) and lodgepole pine (Pinus contorta Dougl. ex Loud.). The second site, Lookout Mountain, is a mixture of ponderosa pine and grand fir (Abies grandis (Dougl. ex D. Don) Lindl.). Both studies were planted in the early 1970's and established as replacement series under a split-plot design with spacing as the whole plot factor and species composition as the split-plot factor. Plot data have been collected since 1975. In the summer of 2001, 95 trees outside the plots were destructively sampled and 114 plots were intensively sampled. From these data the following were developed and assessed: (i) volume growth dynamics; (ii) models predicting individual tree vertical foliage distributions; (iii) models describing the profile of maximum branch diameter within a tree; and (iv) volume growth efficiency. In both studies, the least shade tolerant species had the fastest early growth rates. Over time, volume development depended on both spacing and composition; P. ponderosa was able to catch up with P. contorta within the mixtures and between the pure plots at Pringle Butte, whereas A. grandis still lags behind P. ponderosa, although its relative contribution increases with increasing spacing at Lookout Mountain. Relative yields of mixtures were greater than one, but significantly so only in the A. grandis - P. ponderosa mixtures. Branch leaf area equations indicate that, given branch diameter, position in the crown is an important factor in estimating leaf area. Tree leaf area was best predicted by the product of tree basal area and the ratio of crown length above breast height, a surrogate for sapwood area at crown base. Branch- and tree-level predictions differed significantly between sites for P. ponderosa. Relative vertical foliage distribution on individual trees of both A. grandis and P. ponderosa shifted up with an decrease in relative height, while increased spacing resulted in a downward shift in relative foliage distribution on P. ponderosa at Lookout Mountain. Spacing and competing species also affected absolute foliage distributions in a manner consistent with expected influence on crown length. For all species and spacings, profiles of maximum branch diameter were curvilinear, decreasing near the crown base. Tree variables such as diameter, height, and crown length were able to account for spacing. The effect of species composition on branch profiles was more difficult to assess. Profiles of maximum branch diameter increase with increasing spacing and tree relative height, but the effects of species composition depended on spacing in all species. More pronounced increases in maximum branch diameter profiles with increasing relative height within the crown were found in the subordinate species in mixtures than in adjacent pure plots and in its overtopping competitor. In contrast, the overtopping species had a larger spacing response in the pure plots than in mixed plots. The ratio of leaf biomass to crown biomass decreased with increasing spacing, but was also influenced by species composition. Growth efficiency decreased with increasing spacing, except in Abies grandis, which peaked at the intermediate spacing. Results suggest that plot growth efficiency peaks at intermediate densities depending on composition. At wider spacings, growth efficiency appears to be limited by greater allocation of carbon to branches for both construction and maintenance respiration. At tighter spacings, growth efficiency appears to be limited by competition among individuals, reducing resources per individual and promoting differentiation. In dense, differentiated stands, the poorest individuals contribute leaf area but little growth, reducing stand growth efficiency. Spacing and species composition play an important role in stand development and resulting crown structure. Mixtures can produce a more diverse array of stand structures and yield similar if not more volume than pure stands of the higher yielding species. Management of mixed-species stands must take into account the interactions between spacing and species' growth dynamics, but this same interaction opens possibilities for a wide variety of stand structures for a given species composition. Title: Crown structure, stand dynamics, and production ecology of two species mixtures in the central Oregon Cascades Author: Garber, Sean M. Knowledge of stand structure, stand dynamics, and production ecology of species mixtures lags well behind that of single-species, even-aged stands. Two mixed-species spacing trials in central Oregon allowed investigation of mixed-species dynamics in a controlled experimental setting. The first site, Pringle Butte, is a mixture of ponderosa pine (Pinus ponderosa Dougl. ex Laws.) and lodgepole pine (Pinus contorta Dougl. ex Loud.). The second site, Lookout Mountain, is a mixture of ponderosa pine and grand fir (Abies grandis (Dougl. ex D. Don) Lindl.). Both studies were planted in the early 1970's and established as replacement series under a split-plot design with spacing as the whole plot factor and species composition as the split-plot factor. Plot data have been collected since 1975. In the summer of 2001, 95 trees outside the plots were destructively sampled and 114 plots were intensively sampled. From these data the following were developed and assessed: (i) volume growth dynamics; (ii) models predicting individual tree vertical foliage distributions; (iii) models describing the profile of maximum branch diameter within a tree; and (iv) volume growth efficiency. In both studies, the least shade tolerant species had the fastest early growth rates. Over time, volume development depended on both spacing and composition; P. ponderosa was able to catch up with P. contorta within the mixtures and between the pure plots at Pringle Butte, whereas A. grandis still lags behind P. ponderosa, although its relative contribution increases with increasing spacing at Lookout Mountain. Relative yields of mixtures were greater than one, but significantly so only in the A. grandis - P. ponderosa mixtures. Branch leaf area equations indicate that, given branch diameter, position in the crown is an important factor in estimating leaf area. Tree leaf area was best predicted by the product of tree basal area and the ratio of crown length above breast height, a surrogate for sapwood area at crown base. Branch- and tree-level predictions differed significantly between sites for P. ponderosa. Relative vertical foliage distribution on individual trees of both A. grandis and P. ponderosa shifted up with an decrease in relative height, while increased spacing resulted in a downward shift in relative foliage distribution on P. ponderosa at Lookout Mountain. Spacing and competing species also affected absolute foliage distributions in a manner consistent with expected influence on crown length. For all species and spacings, profiles of maximum branch diameter were curvilinear, decreasing near the crown base. Tree variables such as diameter, height, and crown length were able to account for spacing. The effect of species composition on branch profiles was more difficult to assess. Profiles of maximum branch diameter increase with increasing spacing and tree relative height, but the effects of species composition depended on spacing in all species. More pronounced increases in maximum branch diameter profiles with increasing relative height within the crown were found in the subordinate species in mixtures than in adjacent pure plots and in its overtopping competitor. In contrast, the overtopping species had a larger spacing response in the pure plots than in mixed plots. The ratio of leaf biomass to crown biomass decreased with increasing spacing, but was also influenced by species composition. Growth efficiency decreased with increasing spacing, except in Abies grandis, which peaked at the intermediate spacing. Results suggest that plot growth efficiency peaks at intermediate densities depending on composition. At wider spacings, growth efficiency appears to be limited by greater allocation of carbon to branches for both construction and maintenance respiration. At tighter spacings, growth efficiency appears to be limited by competition among individuals, reducing resources per individual and promoting differentiation. In dense, differentiated stands, the poorest individuals contribute leaf area but little growth, reducing stand growth efficiency. Spacing and species composition play an important role in stand development and resulting crown structure. Mixtures can produce a more diverse array of stand structures and yield similar if not more volume than pure stands of the higher yielding species. Management of mixed-species stands must take into account the interactions between spacing and species' growth dynamics, but this same interaction opens possibilities for a wide variety of stand structures for a given species composition. Close

• 3085. [Article] An evaluation of a water, sanitation, and hygiene (WASH) program for rural communities in northern Afghanistan

  The Water, Sanitation and Hygiene (WASH) sector of international development works to increase access to sustainable, safe water and improved sanitation. Currently, at least 780 million people live without ...

  Citation × Citation Citation Abstract Copy Title: An evaluation of a water, sanitation, and hygiene (WASH) program for rural communities in northern Afghanistan Author: Costello, Denise H. The Water, Sanitation and Hygiene (WASH) sector of international development works to increase access to sustainable, safe water and improved sanitation. Currently, at least 780 million people live without clean drinking water and 2.5 billion without access to improved sanitation (UNICEF & World Health Organization, 2012). Lack of access to these human rights is a major cause of diarrheal disease, which annually kills nearly 760,000 children under the age of five. Many institutions, including the United Nations (UN), non-governmental organizations (NGOs), and local governments are working to resolve this inequality by increasing safe water access, providing sanitation facilities, and improving knowledge and practice of healthy hygiene behaviors. Implementing agencies often self-monitor their efforts and, due to funding challenges, only through the life of the project. This study attempts to evaluate the longer-term effectiveness of an NGO's WASH program in Balkh Province, Afghanistan by investigating five questions, post program 1) was access to safe drinking water improved; 2) how is the spatial distribution of households relative to water sources related to safety of stored drinking water; 3) was there an increase in WASH knowledge; 4) was there an increase in WASH practices; 5) was stored household drinking water safe for consumption? In August to September 2012, an evaluation was conducted of the longer-term effectiveness of a 2009 WASH program in northern Afghanistan. A total of 59 households from four villages took part in the follow-up survey that collected information regarding drinking water, sanitation, health behaviors, and storage or treatment of drinking water. With permission of the participants, drinking water samples were collected and tested for any presence of E. coli, an indicator of fecal contamination. Additionally, samples were taken and analyzed from 15 drinking water sources, 13 of which were public boreholes. Lastly, a Garmin GPS device was used to collect latitude and longitude location of important points during the field research. This information was used to conduct a spatial analysis of well distribution throughout the villages. Survey results showed increases in several beneficial health behaviors, such as using boreholes as the main source of household drinking water, having a specific place to wash hands after using toilet facilities, and having soap in that specific area. Also, based on results of the spatial analysis, access to improved water sources was increased. The practice of treating water in the home dropped significantly. Biosand Filter technology introduced during the WASH program had been adopted by only a small percentage of households. Of the 54 surveyed households that gave permission to sample, 40 had drinking water that tested positive for presence of E. coli. In contrast, a majority of borehole samples provided water that was free of E. coli. Lastly, by examining the spatial distribution of households, it was found that all households beyond 300m from a borehole had drinking water with a presence of E coli. These outcomes make two suggestions. One is that using "1000m from an improved source" as an indicator of accessibility may be too great a distance for households that must collect and carry water, especially when a closer, though contaminated, water option exists. The second is a need for longer term follow-up, especially as behavior change is one of the main goals of the program. More investigation into why families have not adopted handwashing and in home water treatment to a greater extent would be beneficial in creating a stronger WASH program that has greater health impacts. Extended programming is challenging when NGOs are reliant on external funding for program costs. Advocating to funders the importance of longer term monitoring and evaluation as well as reoccurring education programs, could be a vital next step. Title: An evaluation of a water, sanitation, and hygiene (WASH) program for rural communities in northern Afghanistan Author: Costello, Denise H. The Water, Sanitation and Hygiene (WASH) sector of international development works to increase access to sustainable, safe water and improved sanitation. Currently, at least 780 million people live without clean drinking water and 2.5 billion without access to improved sanitation (UNICEF & World Health Organization, 2012). Lack of access to these human rights is a major cause of diarrheal disease, which annually kills nearly 760,000 children under the age of five. Many institutions, including the United Nations (UN), non-governmental organizations (NGOs), and local governments are working to resolve this inequality by increasing safe water access, providing sanitation facilities, and improving knowledge and practice of healthy hygiene behaviors. Implementing agencies often self-monitor their efforts and, due to funding challenges, only through the life of the project. This study attempts to evaluate the longer-term effectiveness of an NGO's WASH program in Balkh Province, Afghanistan by investigating five questions, post program 1) was access to safe drinking water improved; 2) how is the spatial distribution of households relative to water sources related to safety of stored drinking water; 3) was there an increase in WASH knowledge; 4) was there an increase in WASH practices; 5) was stored household drinking water safe for consumption? In August to September 2012, an evaluation was conducted of the longer-term effectiveness of a 2009 WASH program in northern Afghanistan. A total of 59 households from four villages took part in the follow-up survey that collected information regarding drinking water, sanitation, health behaviors, and storage or treatment of drinking water. With permission of the participants, drinking water samples were collected and tested for any presence of E. coli, an indicator of fecal contamination. Additionally, samples were taken and analyzed from 15 drinking water sources, 13 of which were public boreholes. Lastly, a Garmin GPS device was used to collect latitude and longitude location of important points during the field research. This information was used to conduct a spatial analysis of well distribution throughout the villages. Survey results showed increases in several beneficial health behaviors, such as using boreholes as the main source of household drinking water, having a specific place to wash hands after using toilet facilities, and having soap in that specific area. Also, based on results of the spatial analysis, access to improved water sources was increased. The practice of treating water in the home dropped significantly. Biosand Filter technology introduced during the WASH program had been adopted by only a small percentage of households. Of the 54 surveyed households that gave permission to sample, 40 had drinking water that tested positive for presence of E. coli. In contrast, a majority of borehole samples provided water that was free of E. coli. Lastly, by examining the spatial distribution of households, it was found that all households beyond 300m from a borehole had drinking water with a presence of E coli. These outcomes make two suggestions. One is that using "1000m from an improved source" as an indicator of accessibility may be too great a distance for households that must collect and carry water, especially when a closer, though contaminated, water option exists. The second is a need for longer term follow-up, especially as behavior change is one of the main goals of the program. More investigation into why families have not adopted handwashing and in home water treatment to a greater extent would be beneficial in creating a stronger WASH program that has greater health impacts. Extended programming is challenging when NGOs are reliant on external funding for program costs. Advocating to funders the importance of longer term monitoring and evaluation as well as reoccurring education programs, could be a vital next step. Close

• 3086. [Article] “We’ll Be That Kid That You Think We Are” : The Influences of Stigma and Interactions with Important Adults on Youth Identity Development in a Rural Context

  Adolescence is a developmental stage marked by crystallization in individuals’ sense of identity (Erikson, 1994; Harter, 1999). Research on positive youth development stresses the ways in which thriving ...

  Citation × Citation Citation Abstract Copy Title: “We’ll Be That Kid That You Think We Are” : The Influences of Stigma and Interactions with Important Adults on Youth Identity Development in a Rural Context Author: Lile, Joy R. Adolescence is a developmental stage marked by crystallization in individuals’ sense of identity (Erikson, 1994; Harter, 1999). Research on positive youth development stresses the ways in which thriving trajectories during adolescence contribute to positive lifelong outcomes (Lerner & Overton, 2008; Scales, Benson, & Roehlkepartain, 2011) A symbolic interactionism perspective (Mead, 1934) describes how individuals interact with their social contexts to create meaning, which is then incorporated into their personal identities. Rural contexts can present risks and positive assets for youth during this stage. Rural areas are often marked by close-knit social networks (Elder & Conger, 2000), but can suffer from limited access to and unequal distribution of financial and social resources (Carr & Kefalas, 2009; Duncan & Coles, 1999). Poverty and income inequality in rural communities can create stigma (Goffman, 1963; Link & Phelan, 2001) which shapes how resources are distributed across social networks (Sherman, 2009). If rural, low-income youth experience marginalization and stigma due to their low-income status, these experiences may shape their identity development processes. Adult relationships increase in number and significance during middle and late adolescence (Csikszentmihalyi & Schneider, 2001) and positive relationships with adults are a developmental asset for youth (Benson, Scales, & Syvertsen, 2011). Sustained positive relationships with important adults can produce positive outcomes for adolescents, including improved emotional, social, and cognitive skills, as well as positive behavioral outcomes (Beam, Chen, & Greenberger, 2002; DuBois, Portillo, Rhodes, Silverthorn, & Valentine, 2011; Rhodes, Spencer, Keller, Liang, & Noam, 2006). However, low-income youth, especially those in rural settings, may be more isolated from interactions with adults in communities and institutions (Carr & Kefalas, 2009; Lareau, 2003). More research is needed to understand the role that important adults play in adolescent identity development in rural contexts, including the experiences of stigma and positive youth development outcomes. This study explored the effects of stigma and important adults on identity development of low-income adolescents living in a small rural community in Oregon. Data were collected in the rural community of Mountainside, Oregon. The sample includes semi-structured interviews with 16 low-income youth aged 16-18, eight mentors and important non-familial adults identified by youth, and 14 key informants who work in community-oriented professions. Two qualitative interviews were conducted with youth participants, and one interview was conducted with each mentor and key informant. Interviews were analyzed using open and focused coding, in order to address the research questions as well as explore emergent themes (Corbin & Strauss, 2008). Results focused on the construction of meaning around “low-income youth”, and subsequent influences on youth identity development and behaviors. Low-income youth respondents reported many positive strengths and capacities in their own lives, and seemed to hold largely positive self-concepts. Positive identities were supported by relationships with important adults within and outside of youths’ families. Adults in the sample held more pessimistic views of “low-income youth”, seeing them as a problem in the community, and describing their stigmatized status. Youth in the sample experienced constraints due to their low-income and stigmatized statuses which limited their identity development and future outlooks. The findings of this research both support and expand theoretical understandings of stigma, rurality, influences of important adults, and adolescent identity development in context. Implications for research and programming that encourage positive youth development in the contexts of education, family, and community are discussed. Title: “We’ll Be That Kid That You Think We Are” : The Influences of Stigma and Interactions with Important Adults on Youth Identity Development in a Rural Context Author: Lile, Joy R. Adolescence is a developmental stage marked by crystallization in individuals’ sense of identity (Erikson, 1994; Harter, 1999). Research on positive youth development stresses the ways in which thriving trajectories during adolescence contribute to positive lifelong outcomes (Lerner & Overton, 2008; Scales, Benson, & Roehlkepartain, 2011) A symbolic interactionism perspective (Mead, 1934) describes how individuals interact with their social contexts to create meaning, which is then incorporated into their personal identities. Rural contexts can present risks and positive assets for youth during this stage. Rural areas are often marked by close-knit social networks (Elder & Conger, 2000), but can suffer from limited access to and unequal distribution of financial and social resources (Carr & Kefalas, 2009; Duncan & Coles, 1999). Poverty and income inequality in rural communities can create stigma (Goffman, 1963; Link & Phelan, 2001) which shapes how resources are distributed across social networks (Sherman, 2009). If rural, low-income youth experience marginalization and stigma due to their low-income status, these experiences may shape their identity development processes. Adult relationships increase in number and significance during middle and late adolescence (Csikszentmihalyi & Schneider, 2001) and positive relationships with adults are a developmental asset for youth (Benson, Scales, & Syvertsen, 2011). Sustained positive relationships with important adults can produce positive outcomes for adolescents, including improved emotional, social, and cognitive skills, as well as positive behavioral outcomes (Beam, Chen, & Greenberger, 2002; DuBois, Portillo, Rhodes, Silverthorn, & Valentine, 2011; Rhodes, Spencer, Keller, Liang, & Noam, 2006). However, low-income youth, especially those in rural settings, may be more isolated from interactions with adults in communities and institutions (Carr & Kefalas, 2009; Lareau, 2003). More research is needed to understand the role that important adults play in adolescent identity development in rural contexts, including the experiences of stigma and positive youth development outcomes. This study explored the effects of stigma and important adults on identity development of low-income adolescents living in a small rural community in Oregon. Data were collected in the rural community of Mountainside, Oregon. The sample includes semi-structured interviews with 16 low-income youth aged 16-18, eight mentors and important non-familial adults identified by youth, and 14 key informants who work in community-oriented professions. Two qualitative interviews were conducted with youth participants, and one interview was conducted with each mentor and key informant. Interviews were analyzed using open and focused coding, in order to address the research questions as well as explore emergent themes (Corbin & Strauss, 2008). Results focused on the construction of meaning around “low-income youth”, and subsequent influences on youth identity development and behaviors. Low-income youth respondents reported many positive strengths and capacities in their own lives, and seemed to hold largely positive self-concepts. Positive identities were supported by relationships with important adults within and outside of youths’ families. Adults in the sample held more pessimistic views of “low-income youth”, seeing them as a problem in the community, and describing their stigmatized status. Youth in the sample experienced constraints due to their low-income and stigmatized statuses which limited their identity development and future outlooks. The findings of this research both support and expand theoretical understandings of stigma, rurality, influences of important adults, and adolescent identity development in context. Implications for research and programming that encourage positive youth development in the contexts of education, family, and community are discussed. Close

• 3087. [Article] Evolution of Turbulence, Heat Content, and Freshwater Lenses in the Diurnal Warm Layer

  Thorough understanding of the mechanisms controlling the temperature structure in the surface mixed layer of the ocean and, in particular, accurate values of sea surface temperature are critical for properly ...

  Citation × Citation Citation Abstract Copy Title: Evolution of Turbulence, Heat Content, and Freshwater Lenses in the Diurnal Warm Layer Author: Moulin, Aurélie J. Thorough understanding of the mechanisms controlling the temperature structure in the surface mixed layer of the ocean and, in particular, accurate values of sea surface temperature are critical for properly parameterizing air-sea heat exchange and quantifying the amount of heat redistributed below the surface. It is however difficult to obtain routine in-situ measurements of the sea surface temperature from oceanographic moorings or research vessels, and even more difficult to measure the detailed evolution of the temperature structure. Oceanographers instead rely on parameterizations of a diurnal warm layer forced by temperature profiles or time series to estimate the time-varying surface temperature structure. For the first time, the time-varying near-surface temperature structure, turbulence and surface heat fluxes were measured at the same time in the Indian Ocean during the DYNAMO field experiment. These measurements showed the abrupt termination of nighttime mixing at sunrise and subsequent decay during approximately one hour, they showed a rapid growth of turbulence thereafter as a balance of shear and buoyancy production and turbulent kinetic energy dissipation, and they showed an equilibrium state in the afternoon. Elevated turbulence were attributed to shear instabilities from the observation of temperature ramps in low-moderate wind conditions, but could not be distinguished from Langmuir circulations in higher winds. Distinct relationships of the vertical temperature gradient, wind speed and turbulence dissipation emerged when classifying data by presence of temperature ramps. These measurements also permitted a re-assessment of the vertical structure and physics of the diurnal warm layer with implications for heat budget assessment, therefore helping to identify weaknesses in current parameterizations. The shape of temperature profiles results from the ability of turbulence to export downward the heat deposited near the surface by exponentially attenuated subsurface solar radiation. When stratification was weak in the early morning surface heat was distributed over the top eight meters resulting in heat in excess of local solar radiation divergence. After complete restratification, surface heat was trapped above the mixed layer depth where it was both input from local divergence of the absorbed solar radiation and from the downwelling of surface heat through mixing. Below the mixed layer, the divergence of attenuated solar radiations was the only heat source. Shear instabilities at the base of the mixed layer entrain cooler fluid from below thereby deepening the mixed layer depth and distributing heat and momentum over a thicker layer. In late afternoon when net surface cooling exceeded the net heating from the divergence of penetrating solar radiation, the temperature structure was destabilized from above, mixing heat downward. The heat accumulated over the previous hours and stored in the mixed layer was then eroded both from above through convection and from below through shear instabilities. Our observations also permitted a detailed look at freshwater lenses deposited by strong localized precipitation, which can affect the heat content directly from the addition of cooler rainwater, but also indirectly by modifying the stratification of the upper ocean. Twenty-six lenses were identified, ten of which propagated at the internal wave speed and featured buoyant gravity current characteristics. The temperature and salinity anomalies of lenses were related to their age and rain volume precipitated, and they were either cooler or warmer than ambient water. This propensity to retain heat created a patchy temperature environment both at the surface and in the near-surface as pockets of warm and cool water were observed within lenses. Thermohaline anomalies were estimated to dissipate in three days on average, but up to 25 days, if the turbulent mixing of ambient water was the only source of heat and salt. Title: Evolution of Turbulence, Heat Content, and Freshwater Lenses in the Diurnal Warm Layer Author: Moulin, Aurélie J. Thorough understanding of the mechanisms controlling the temperature structure in the surface mixed layer of the ocean and, in particular, accurate values of sea surface temperature are critical for properly parameterizing air-sea heat exchange and quantifying the amount of heat redistributed below the surface. It is however difficult to obtain routine in-situ measurements of the sea surface temperature from oceanographic moorings or research vessels, and even more difficult to measure the detailed evolution of the temperature structure. Oceanographers instead rely on parameterizations of a diurnal warm layer forced by temperature profiles or time series to estimate the time-varying surface temperature structure. For the first time, the time-varying near-surface temperature structure, turbulence and surface heat fluxes were measured at the same time in the Indian Ocean during the DYNAMO field experiment. These measurements showed the abrupt termination of nighttime mixing at sunrise and subsequent decay during approximately one hour, they showed a rapid growth of turbulence thereafter as a balance of shear and buoyancy production and turbulent kinetic energy dissipation, and they showed an equilibrium state in the afternoon. Elevated turbulence were attributed to shear instabilities from the observation of temperature ramps in low-moderate wind conditions, but could not be distinguished from Langmuir circulations in higher winds. Distinct relationships of the vertical temperature gradient, wind speed and turbulence dissipation emerged when classifying data by presence of temperature ramps. These measurements also permitted a re-assessment of the vertical structure and physics of the diurnal warm layer with implications for heat budget assessment, therefore helping to identify weaknesses in current parameterizations. The shape of temperature profiles results from the ability of turbulence to export downward the heat deposited near the surface by exponentially attenuated subsurface solar radiation. When stratification was weak in the early morning surface heat was distributed over the top eight meters resulting in heat in excess of local solar radiation divergence. After complete restratification, surface heat was trapped above the mixed layer depth where it was both input from local divergence of the absorbed solar radiation and from the downwelling of surface heat through mixing. Below the mixed layer, the divergence of attenuated solar radiations was the only heat source. Shear instabilities at the base of the mixed layer entrain cooler fluid from below thereby deepening the mixed layer depth and distributing heat and momentum over a thicker layer. In late afternoon when net surface cooling exceeded the net heating from the divergence of penetrating solar radiation, the temperature structure was destabilized from above, mixing heat downward. The heat accumulated over the previous hours and stored in the mixed layer was then eroded both from above through convection and from below through shear instabilities. Our observations also permitted a detailed look at freshwater lenses deposited by strong localized precipitation, which can affect the heat content directly from the addition of cooler rainwater, but also indirectly by modifying the stratification of the upper ocean. Twenty-six lenses were identified, ten of which propagated at the internal wave speed and featured buoyant gravity current characteristics. The temperature and salinity anomalies of lenses were related to their age and rain volume precipitated, and they were either cooler or warmer than ambient water. This propensity to retain heat created a patchy temperature environment both at the surface and in the near-surface as pockets of warm and cool water were observed within lenses. Thermohaline anomalies were estimated to dissipate in three days on average, but up to 25 days, if the turbulent mixing of ambient water was the only source of heat and salt. Close

• 3088. [Article] Measuring protein metal binding via mass spectrometry : copper, zinc superoxide dismutase and amyotrophic lateral sclerosis

  Amyotrophic lateral sclerosis (ALS) is a devastating disease characterized by the progressive degeneration of motor neurons. Dominantly-inherited mutations to the antioxidant enzyme Cu,Zn superoxide dismutase ...

  Citation × Citation Citation Abstract Copy Title: Measuring protein metal binding via mass spectrometry : copper, zinc superoxide dismutase and amyotrophic lateral sclerosis Author: Rhoads, Timothy W. Amyotrophic lateral sclerosis (ALS) is a devastating disease characterized by the progressive degeneration of motor neurons. Dominantly-inherited mutations to the antioxidant enzyme Cu,Zn superoxide dismutase (SOD1) cause 3-6% of all ALS cases. The complete mechanism behind the toxicity of mutant SOD1 remains unclear, although significant evidence points to aberrant or incomplete metal-binding having a role in a toxic gain-of-function. However, the relevance of the metal-binding of SOD1 to mutant-SOD1-linked ALS remains controversial. Direct assessments of protein metal-binding from transgenic, SOD1-overexpressing rodent models of the disease are difficult to acquire due to the non-covalent nature of the interaction. The relatively small amount of disease-afflicted spinal cord tissue in which the motor neurons reside compounds the difficulty of measuring the protein metal binding of SOD1 from transgenic mice. This dissertation addresses the metals bound to SOD1 throughout the disease course in transgenic mice using a novel mass spectrometry assay. The methodology developed here offers the first detailed examination of partially unfolded intermediates of SOD1 present in the spinal cord of pre-symptomatic, symptomatic, and end-stage transgenic mice overexpressing the ALS-associated SOD1 mutation G93A (glycine mutated to alanine at position 93). These results were compared to age-matched transgenic mice expressing wild-type SOD1 that do not develop ALS symptoms. To extract SOD1 from relevant spinal cord tissue, a 300 μm necropsy punch was used to remove a small piece of tissue from the ventral or dorsal gray matter of a 1 mm-thick slice of spinal cord. Physiological salts that interfere with electrospray mass spectrometry were removed by binding the proteins to a C4 Ziptip®, a pipette tip containing hydrophobic, reversed-phase packing material. Washing the Ziptip-bound proteins with water eliminated interfering salts. Bound proteins could then be eluted into a mass spectrometer with low concentrations of acetonitrile plus formic acid. Electrospray ionization conditions were determined that could keep both copper and zinc bound to SOD1. Using a high-resolution Fourier transform-ion cyclotron resonance mass spectrometer, we used the assay to collect isotopically-resolved protein mass data. Theoretical protein isotope distributions were calculated from the empirical formulas of SOD1 and matched to the experimental data with a least squares fitting algorithm to determine the multiple intermediates of SOD1 present. Spinal cord tissue, wild-type in particular, was notable for containing significantly more one-metal SOD1 than any other tissue, despite having 3-fold less SOD1 than liver. We quantitatively compared the levels of soluble, partially unfolded intermediates of SOD1 from wild-type and G93A SOD1 spinal cords. Wild-type mouse spinal cord contained significantly more of all of the partially unfolded intermediates copper-deficient SOD1, disulfide reduced SOD1, and apo SOD1. The amount of zinc-containing SOD1 was exceptionally high in wild-type mice, comprising 60% of the total SOD1 in wild-type spinal cord. The larger amounts of these SOD1 intermediates in wild-type transgenic mice indicate that they are not directly responsible for toxicity in vivo. However, copper-containing, zinc-deficient SOD1 was the one species found in higher concentrations in G93A SOD1 spinal cord. The concentration was on average 0.6-0.8 μM in G93A spinal cord, compared to 0.1-0.3 μM zinc-deficient SOD1 found in the wild-type mouse spinal cord. A concentration above 0.5 μM zinc-deficient SOD1 was sufficient to induce motor neuron death in vitro. These results suggest that copper-containing, zinc-deficient SOD1 could be the toxic species responsible for motor neuron death in ALS. Title: Measuring protein metal binding via mass spectrometry : copper, zinc superoxide dismutase and amyotrophic lateral sclerosis Author: Rhoads, Timothy W. Amyotrophic lateral sclerosis (ALS) is a devastating disease characterized by the progressive degeneration of motor neurons. Dominantly-inherited mutations to the antioxidant enzyme Cu,Zn superoxide dismutase (SOD1) cause 3-6% of all ALS cases. The complete mechanism behind the toxicity of mutant SOD1 remains unclear, although significant evidence points to aberrant or incomplete metal-binding having a role in a toxic gain-of-function. However, the relevance of the metal-binding of SOD1 to mutant-SOD1-linked ALS remains controversial. Direct assessments of protein metal-binding from transgenic, SOD1-overexpressing rodent models of the disease are difficult to acquire due to the non-covalent nature of the interaction. The relatively small amount of disease-afflicted spinal cord tissue in which the motor neurons reside compounds the difficulty of measuring the protein metal binding of SOD1 from transgenic mice. This dissertation addresses the metals bound to SOD1 throughout the disease course in transgenic mice using a novel mass spectrometry assay. The methodology developed here offers the first detailed examination of partially unfolded intermediates of SOD1 present in the spinal cord of pre-symptomatic, symptomatic, and end-stage transgenic mice overexpressing the ALS-associated SOD1 mutation G93A (glycine mutated to alanine at position 93). These results were compared to age-matched transgenic mice expressing wild-type SOD1 that do not develop ALS symptoms. To extract SOD1 from relevant spinal cord tissue, a 300 μm necropsy punch was used to remove a small piece of tissue from the ventral or dorsal gray matter of a 1 mm-thick slice of spinal cord. Physiological salts that interfere with electrospray mass spectrometry were removed by binding the proteins to a C4 Ziptip®, a pipette tip containing hydrophobic, reversed-phase packing material. Washing the Ziptip-bound proteins with water eliminated interfering salts. Bound proteins could then be eluted into a mass spectrometer with low concentrations of acetonitrile plus formic acid. Electrospray ionization conditions were determined that could keep both copper and zinc bound to SOD1. Using a high-resolution Fourier transform-ion cyclotron resonance mass spectrometer, we used the assay to collect isotopically-resolved protein mass data. Theoretical protein isotope distributions were calculated from the empirical formulas of SOD1 and matched to the experimental data with a least squares fitting algorithm to determine the multiple intermediates of SOD1 present. Spinal cord tissue, wild-type in particular, was notable for containing significantly more one-metal SOD1 than any other tissue, despite having 3-fold less SOD1 than liver. We quantitatively compared the levels of soluble, partially unfolded intermediates of SOD1 from wild-type and G93A SOD1 spinal cords. Wild-type mouse spinal cord contained significantly more of all of the partially unfolded intermediates copper-deficient SOD1, disulfide reduced SOD1, and apo SOD1. The amount of zinc-containing SOD1 was exceptionally high in wild-type mice, comprising 60% of the total SOD1 in wild-type spinal cord. The larger amounts of these SOD1 intermediates in wild-type transgenic mice indicate that they are not directly responsible for toxicity in vivo. However, copper-containing, zinc-deficient SOD1 was the one species found in higher concentrations in G93A SOD1 spinal cord. The concentration was on average 0.6-0.8 μM in G93A spinal cord, compared to 0.1-0.3 μM zinc-deficient SOD1 found in the wild-type mouse spinal cord. A concentration above 0.5 μM zinc-deficient SOD1 was sufficient to induce motor neuron death in vitro. These results suggest that copper-containing, zinc-deficient SOD1 could be the toxic species responsible for motor neuron death in ALS. Close

• 3089. [Article] Transforming social relations : how caregiving sons "do" gender subversively

  In this dissertation, I explored how social relationships influence, and are influenced by, men's experiences of caregiving to their aging parents. Because of sociodemographic trends such as fewer siblings ...

  Citation × Citation Citation Abstract Copy Title: Transforming social relations : how caregiving sons "do" gender subversively Author: Hirayama, Ryo In this dissertation, I explored how social relationships influence, and are influenced by, men's experiences of caregiving to their aging parents. Because of sociodemographic trends such as fewer siblings in younger generations and the growth of women seeking professional careers, men are increasingly likely to be called upon to meet parental care needs. When assuming care responsibility for their parents, however, men must confront the gender ideology that defines family caregiving as "women's work." Positioning social relationships as a component of men's gendered experiences of parental caregiving, I addressed two research questions. First, I sought to understand the role of social relationships in caregiving sons' negotiation of masculinity. Second, I examined whether and how caregiving sons (re)organize their social networks so as to better manage care responsibility. In pursuing these questions, my ultimate goals were to identify (a) whether and how men's parental caregiving can subvert gender relations, and (b) whether and how social partners link men's experiences of parental caregiving to gendered structural arrangements. In this research, I focused on caregiving sons in Japan, where, despite an increase in sons who (are required to) take on the role of parental caregiver, men's parental caregiving is still seen as "atypical." This dissertation consists of three studies. In the first study, I sought to clarify how Japanese men typically view and carry out care responsibility for their parents in relation to traditional familial institutions, Ie, that are comprised of multiple norms regarding such dimensions as birth order, inheritance, and the family membership of married women. Using data from a nationally representative sample of men in Japan (N = 964), results of latent class analyses indicated that Japanese men can be classified into three groups according to level of conformity to each norm in the Ie tradition. Further, through multiple group regression analyses on men with at least one living parent in the sample (n = 553), I found family circumstances associated with their actual involvement in parental caregiving differ across the three groups. The results suggest possible sociohistorical changes in the influence of Ie ideas on Japanese men's views about and styles of parental caregiving. In the second study, from the perspective of doing gender, I examined how caregiving sons account for their atypical family role, with particular attention paid to their nonnormative use of normative conceptions of gender and family. Using a constructivist version of grounded theory applied to interview data from adult sons in Japan who are primary caregivers for their parents with dementia (N = 21), I found they attempt to legitimize their care responsibility by invoking (a) traditional Ie norms and (b) stereotypical ideas about masculinity/femininity, both of which have been used in the past to tie women to family caregiving. The findings suggest that sons might deconstruct normative conceptions in an attempt to frame their parental caregiving as accountable. In the final study grounded in social convoy theory, I examined (a) how Japanese caregiving sons perceive feedback about their caregiving from members of their social networks, and (b) how, in response, they reconstruct their social relationships. Using a constructivist version of grounded theory, I analyzed interview data from adult sons in the role of primary caregivers for their parents who have dementia (N = 21). Despite relatively frequent contact with colleagues, friends, and neighbors, to avoid possible negative reactions, sons rarely told these network members about their care experiences; thus, their parental caregiving was compartmentalized from other aspects of their social lives. The findings suggest that the restricted social relationships of caregiving sons are at least partly the product of their efforts to assume parental care responsibility in a society that marginalizes men's caregiving. In conclusion, although parental caregiving is a likely context in which men might destabilize the ideological basis for gender relations within attempts to do gender, their network members appear to compel them to confine such subversive gender performance within the caregiving setting. At the same time, the findings also suggest that men in younger generations may take on the role of parental caregiver in different social environments than that of their older counterparts. Building on these findings, I offer suggestions about how to approach both caregiving sons' and their social partners' ideas about gender such that these sons can be more open about their care experiences. Title: Transforming social relations : how caregiving sons "do" gender subversively Author: Hirayama, Ryo In this dissertation, I explored how social relationships influence, and are influenced by, men's experiences of caregiving to their aging parents. Because of sociodemographic trends such as fewer siblings in younger generations and the growth of women seeking professional careers, men are increasingly likely to be called upon to meet parental care needs. When assuming care responsibility for their parents, however, men must confront the gender ideology that defines family caregiving as "women's work." Positioning social relationships as a component of men's gendered experiences of parental caregiving, I addressed two research questions. First, I sought to understand the role of social relationships in caregiving sons' negotiation of masculinity. Second, I examined whether and how caregiving sons (re)organize their social networks so as to better manage care responsibility. In pursuing these questions, my ultimate goals were to identify (a) whether and how men's parental caregiving can subvert gender relations, and (b) whether and how social partners link men's experiences of parental caregiving to gendered structural arrangements. In this research, I focused on caregiving sons in Japan, where, despite an increase in sons who (are required to) take on the role of parental caregiver, men's parental caregiving is still seen as "atypical." This dissertation consists of three studies. In the first study, I sought to clarify how Japanese men typically view and carry out care responsibility for their parents in relation to traditional familial institutions, Ie, that are comprised of multiple norms regarding such dimensions as birth order, inheritance, and the family membership of married women. Using data from a nationally representative sample of men in Japan (N = 964), results of latent class analyses indicated that Japanese men can be classified into three groups according to level of conformity to each norm in the Ie tradition. Further, through multiple group regression analyses on men with at least one living parent in the sample (n = 553), I found family circumstances associated with their actual involvement in parental caregiving differ across the three groups. The results suggest possible sociohistorical changes in the influence of Ie ideas on Japanese men's views about and styles of parental caregiving. In the second study, from the perspective of doing gender, I examined how caregiving sons account for their atypical family role, with particular attention paid to their nonnormative use of normative conceptions of gender and family. Using a constructivist version of grounded theory applied to interview data from adult sons in Japan who are primary caregivers for their parents with dementia (N = 21), I found they attempt to legitimize their care responsibility by invoking (a) traditional Ie norms and (b) stereotypical ideas about masculinity/femininity, both of which have been used in the past to tie women to family caregiving. The findings suggest that sons might deconstruct normative conceptions in an attempt to frame their parental caregiving as accountable. In the final study grounded in social convoy theory, I examined (a) how Japanese caregiving sons perceive feedback about their caregiving from members of their social networks, and (b) how, in response, they reconstruct their social relationships. Using a constructivist version of grounded theory, I analyzed interview data from adult sons in the role of primary caregivers for their parents who have dementia (N = 21). Despite relatively frequent contact with colleagues, friends, and neighbors, to avoid possible negative reactions, sons rarely told these network members about their care experiences; thus, their parental caregiving was compartmentalized from other aspects of their social lives. The findings suggest that the restricted social relationships of caregiving sons are at least partly the product of their efforts to assume parental care responsibility in a society that marginalizes men's caregiving. In conclusion, although parental caregiving is a likely context in which men might destabilize the ideological basis for gender relations within attempts to do gender, their network members appear to compel them to confine such subversive gender performance within the caregiving setting. At the same time, the findings also suggest that men in younger generations may take on the role of parental caregiver in different social environments than that of their older counterparts. Building on these findings, I offer suggestions about how to approach both caregiving sons' and their social partners' ideas about gender such that these sons can be more open about their care experiences. Close

• 3090. [Article] Spatial and Temporal Effects of Large Truck-Involved Crash Injury Severities : A Mixed Logit Analysis

  Large truck-involved crashes have a significant impact on both the economy and society. They are associated with high injury severities, high crash costs and contribute to congestion in urban areas. Past ...

  Citation × Citation Citation Abstract Copy Title: Spatial and Temporal Effects of Large Truck-Involved Crash Injury Severities : A Mixed Logit Analysis Author: Pahukula, Jasmine Large truck-involved crashes have a significant impact on both the economy and society. They are associated with high injury severities, high crash costs and contribute to congestion in urban areas. Past studies have investigated the contributing factors of large truck-involved crashes, however a study isolating the spatial and temporal effects is lacking. This thesis aims to bridge that gap as well as provide practical applications to improve safety from a large truck perspective through two new frameworks. This thesis contains two standalone documents, each detailing the spatial and temporal transferability framework, separately. These frameworks provide additional information that can be utilized in the development of planning tools to ultimately improve safety. Random parameters logit models (i.e. mixed logit models) were utilized to help identify the contributing factors of large truck-involved crashes. One advantage of the mixed logit model is that it can account for the unobserved heterogeneity in the model which relaxes the independence of irrelevant alternatives (IIA) property. A series of log likelihood ratio tests were utilized to determine if transferability, spatial or temporal, was warranted. The first document details the spatial transferability framework which is demonstrated through a case study on large truck-involved crashes in urban areas in Oregon and Texas. Strict regulations imposed on the trucking industry limits the variability of heavy-vehicle configurations and enhance the standards for truck drivers (as opposed to passenger vehicle drivers). Encouraging consistency between large trucks is one way to improve safety and has also lead to the investigation of commonalities between large truck-involved crashes in two spatially distributed regions. The results of the log-likelihood ratio tests indicate that spatial transferability is not warranted between Oregon and Texas. Key differences were non-driver or 'uncontrollable' characteristics (e.g. weather, light conditions and time of day) while driver related characteristics (e.g. gender, age and restraint use) had similar impacts. Since the major differences include non-driver characteristics, perhaps a regional model with similar 'uncontrollable' characteristics is warranted. The second document illustrates the temporal transferability framework which is applied to large truck-involved crashes in urban areas in Texas. Traffic patterns, light conditions and driver behavior vary throughout the day and consequently can have a varied impact on large truck-involved crashes. The results of the log likelihood ratio tests indicate that temporal transferability is warranted and the database was divided into five time periods to be analyzed separately. Traffic flow, light conditions, surface conditions, month and percentage of trucks on the road were among the significant differences between the crash factors of each time period. The two proposed transferability frameworks, spatial and temporal, provide new information that can be integrated into safety planning tools and more sharply guide decision-makers. For example, the results of this thesis can help to pinpoint temporal or spatial-related countermeasures. In addition the results of this thesis can help in the allocation of limited resources (i.e. help prioritize projects), minimize economic loss and help decision makers improve safety from a large truck perspective (e.g. modify trucking regulations). Finally, this thesis provides a foundation for future research. As indicated in Chapter 2, a future study to evaluate the feasibility of a regional large truck-involved crash model between neighboring regions and the development of a national crash data reporting standard are potential ideas for future research. Chapter 3 stressed the importance of time of day on large truck-involved crashes which can serve as the basis to study the safety and economic impacts of time of day shifts of truck freight movements to off-peak periods. In summary, this thesis involves original research that expands the literature and provides a new foundation to analyze large truck-involved crashes. Title: Spatial and Temporal Effects of Large Truck-Involved Crash Injury Severities : A Mixed Logit Analysis Author: Pahukula, Jasmine Large truck-involved crashes have a significant impact on both the economy and society. They are associated with high injury severities, high crash costs and contribute to congestion in urban areas. Past studies have investigated the contributing factors of large truck-involved crashes, however a study isolating the spatial and temporal effects is lacking. This thesis aims to bridge that gap as well as provide practical applications to improve safety from a large truck perspective through two new frameworks. This thesis contains two standalone documents, each detailing the spatial and temporal transferability framework, separately. These frameworks provide additional information that can be utilized in the development of planning tools to ultimately improve safety. Random parameters logit models (i.e. mixed logit models) were utilized to help identify the contributing factors of large truck-involved crashes. One advantage of the mixed logit model is that it can account for the unobserved heterogeneity in the model which relaxes the independence of irrelevant alternatives (IIA) property. A series of log likelihood ratio tests were utilized to determine if transferability, spatial or temporal, was warranted. The first document details the spatial transferability framework which is demonstrated through a case study on large truck-involved crashes in urban areas in Oregon and Texas. Strict regulations imposed on the trucking industry limits the variability of heavy-vehicle configurations and enhance the standards for truck drivers (as opposed to passenger vehicle drivers). Encouraging consistency between large trucks is one way to improve safety and has also lead to the investigation of commonalities between large truck-involved crashes in two spatially distributed regions. The results of the log-likelihood ratio tests indicate that spatial transferability is not warranted between Oregon and Texas. Key differences were non-driver or 'uncontrollable' characteristics (e.g. weather, light conditions and time of day) while driver related characteristics (e.g. gender, age and restraint use) had similar impacts. Since the major differences include non-driver characteristics, perhaps a regional model with similar 'uncontrollable' characteristics is warranted. The second document illustrates the temporal transferability framework which is applied to large truck-involved crashes in urban areas in Texas. Traffic patterns, light conditions and driver behavior vary throughout the day and consequently can have a varied impact on large truck-involved crashes. The results of the log likelihood ratio tests indicate that temporal transferability is warranted and the database was divided into five time periods to be analyzed separately. Traffic flow, light conditions, surface conditions, month and percentage of trucks on the road were among the significant differences between the crash factors of each time period. The two proposed transferability frameworks, spatial and temporal, provide new information that can be integrated into safety planning tools and more sharply guide decision-makers. For example, the results of this thesis can help to pinpoint temporal or spatial-related countermeasures. In addition the results of this thesis can help in the allocation of limited resources (i.e. help prioritize projects), minimize economic loss and help decision makers improve safety from a large truck perspective (e.g. modify trucking regulations). Finally, this thesis provides a foundation for future research. As indicated in Chapter 2, a future study to evaluate the feasibility of a regional large truck-involved crash model between neighboring regions and the development of a national crash data reporting standard are potential ideas for future research. Chapter 3 stressed the importance of time of day on large truck-involved crashes which can serve as the basis to study the safety and economic impacts of time of day shifts of truck freight movements to off-peak periods. In summary, this thesis involves original research that expands the literature and provides a new foundation to analyze large truck-involved crashes. Close