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Conventional clinical histopathology analysis is based on bright-field microscopy of thinly sliced tissue specimens. Although bright-field microscopy is a simple and robust method for examining microscope slides, preparing the slides needed is a lengthy and labor-intensive process. Slide-free histopathology technologies address this problem by directly imaging intact, minimally processed tissue samples using advanced optical imaging systems, bypassing the extended workflow now required for preparation of tissue sections. This manuscript explains the technical basis of slide-free microscopy, reviews common slide-free optical microscopy techniques, and discusses the opportunities and challenges involved in clinical implementation.

Despite their long history as a forest dominant, the importance of Quercus (oak) species is declining under contemporary disturbance regimes in many parts of the world. This is cause for concern considering the great economic and ecological value of this genus. While many chronosequence studies have shown that clearcutting has accelerated the loss of Quercus species in forests of eastern North America, long-term repeated measures studies are needed to understand how topo-edaphic variables and disturbance history influence the persistence of the genus in post-harvest stands. In 1988, a study was implemented on the Hoosier National Forest (HNF) in southern Indiana, USA to examine the fate of Quercus species and their competitors within developing stands following clearcut harvests. Permanent plots were established in six harvest units in Quercus-Carya (oak-hickory) forests using a stratified design to capture a variety of physiographic and edaphic conditions. Pre-harvest plot data were collected in 1988 and plots were resampled in 2011, allowing documentation of shifts in species composition over a 23-year period (1988–2011). Aerial photos from the 1930s were used to determine canopy cover and likely historic land-use within each stand prior to incorporation into the HNF. To characterize edaphic conditions, soil samples were collected and analyzed for chemical characteristics in 2011. Non-metric multidimensional scaling (NMS) and multiple linear regression using fixed and mixed-effect models were used to examine species composition along topo-edaphic and historic canopy cover gradients. We observed drastic declines in the importance of Quercus alba (white oak), Quercus velutina (black oak), and Quercus prinus (chestnut oak) across all stands following harvest. During the same time period, we observed large increases in the importance of other species, with Acer rubrum (red maple) showing large increases on the driest sites and Liriodendron tulipifera (tulip-poplar) displaying the greatest increase across all sites. In pre-harvest stands, Q. prinus was confined to the poorest sites and displayed the strongest association of all species with historically closed canopies in both pre and post-harvest stands. In post-harvest stands, the diminished importance of Q. alba was associated with low soil nitrogen levels and historically open canopies. L. tulipifera and Prunus serotina (black cherry) were associated with more nutrient-rich mesic sites in post-harvest stands. Populus grandidentata (bigtooth aspen) in post-harvest stands was associated with historically closed canopies and low cation exchange capacity.

High-temperature damage evolution in pure W and W-5Re has been studied by combining transmission electron microscopy and in-situ irradiations with 10 keV He+ ions. The irradiations covered a temperature range of Tirr = 773–1473 K and a fluence range of (4.5–15) × 1019 He+/m2. In pure W, detailed characterizations have shown that damage evolution is highly dependent upon the foil thickness. Regions of thickness

Invasive woody plant species are a threat to biodiversity and ecosystem function in forests of the eastern U.S., due in part to their effects on soil properties and nutrient cycling. Controlling invasive shrubs can benefit the ecosystem at multiple scales, but these species tend to resprout when cut, and post-cutting flushes of root exudates have been linked to accelerated decomposition of soil organic matter (SOM), a rhizosphere priming effect. We removed the invasive shrub Lonicera maackii (Rupr.) Herder (Amur honeysuckle) from forested sites in central Indiana, USA, using cut-stump and forestry mulching head treatments. For two growing seasons after the initial removal treatments, we compared the soil chemistry and microbial community function of bulk and honeysuckle rhizosphere soils in shrub removal areas to those in invaded reference areas. Microbial activity measured using multiple substrate induced respiration (MSIR) in bulk soils was generally lower in removal areas than reference areas the first year, coinciding with relatively elevated responses in the rhizosphere soils of resprouting shrubs. Elevated SOM and organic C in rhizosphere soils of resprouting shrubs suggested a flush of rhizodeposits from cutting and regrowth. However, bulk soil chemistry responses to shrub removal did not show any evidence of a rhizosphere priming effect, but instead reflected the reduced effects of honeysuckle on throughfall precipitation chemistry—higher ammonium and lower magnesium. Nonetheless, changes in bulk soil chemistry between years were driven by the chemical characteristics of rhizosphere soil associated with resprouting honeysuckle. This study is the first to document the potential for invasive shrub control to affect soil properties through rhizodeposition by the target species.

Declines in the diversity of herbaceous and woody plant species in the understory of eastern North American hardwood forests are increasingly common. Forest managers are tasked with maintaining and/or promoting species diversity and resilience; however, the success of these efforts depends on a robust understanding of past and future system dynamics and identification and application of appropriate silvicultural interventions. We review how historical timber harvesting and land use, increases in deer population sizes, invasive species, and contemporary forest management practices interact to erode ecological memory and increase resilience debt of hardwood forests of eastern North America. The erosion of ecological memory and growing resilience debt in these forests pose significant challenges for forest managers because they alter the response of forests to management from the understory to overstory. Differences in how much ecological memory these systems retain, as well as the mosaic of interacting factors influencing contemporary dynamics, preclude a one size fits all management approach. That being said, our review has identified a host of common factors and pathways that can be manipulated. The approach we propose requires a more thoughtful understanding of the forest understory as the foundation upon which resilient systems are built. Which silvicultural levers will have the greatest utility clearly depend on the ecological context of the forest, and a willingness to experiment and adapt. We offer a conceptual model and recommendations for managers confronting novel plant communities and uncertain system dynamics.

Hickories (Carya spp.) are common species in eastern US forests. Despite being a noted component of the most prevalent forest type in the eastern US, remarkably little is known about the ecology and silvics of the genera, especially compared to oaks (Quercus spp.). To improve our understanding about the dynamics of hickories in stand development and forest succession, we used a variety of datasets from oak-hickory forests of the Central Hardwood Region to assess growth, physiology, and demography. Our findings suggest that hickories may have a conservative root-centered growth strategy that exceeds that of oaks, with highly plastic physiology. This allows for long-term persistence of hickories in the mid and understory while being responsive to favorable increases in available light. The reproduction dynamics of hickories suggest a gradual and consistent recruitment to the mid and overstory in contrast to the single, unimodal age distribution of oaks following historic disturbance. This is achieved by periods of higher growth rates and lower mortality rates, especially in subordinate canopy positions when compared to oaks. These findings suggest that contemporary removal of historic disturbance regimes may continue to support hickory recruitment to the overstory, but active forest management is necessary to maintain the oak-hickory forest type in the Central Hardwood Region.

Little is known about fuel characteristics and dynamics in GBBP communities, and current monitoring programs inadequately quantify the surface and canopy fuels of this system. Using the Forest Inventory Analysis (FIA) plot variables of tree species, height, diameter at breast height (DBH), canopy base height (CBH), coarse (CWD) and fine (FWD) woody debris counts, and canopy fuels measurements, this paper examines the effects of climate-induced changes to fuel loading, fire hazard and risk on predicted changes in fire behavior and severity. Field transects were installed using FIA protocols along environmental gradients. Plots were located every 22 chains or ∼440 m along random transects on Mt. Washington in the Great Basin National Park (GBNP) and in the nearby Mt. Moriah Wilderness, NV. Additional plots were installed at Notch Peak (UT), Cave Mountain (NV), and Wheeler Peak (GBNP, NV). Linear regression showed that all classes of FWD decreased with elevation, and only 1000-h fuels remained constant across elevational transects. This, combined with lower CBH and foliar moisture and increasing temperatures due to climate change, increases fire potential at the Great Basin bristlecone pine treeline, threatening the oldest individuals of this iconic species. New information about discontinuous fuels will aid in management of high elevation alpine treeline forests.

Mountain pine beetle (MPB; Dendroctonus ponderosae Hopkins) causes extensive tree mortality in whitebark pine (Pinus albicaulis Engelm) forests. Previous studies conducted in lodgepole pine (Pinus contorta Douglas), Douglas-fir (Pseudotsuga menziesii (mirb.) Franco), and Engelmann spruce (Picea engelmanni Parry ex. Engelm) have shown that litter, duff, and 1-h (

We resampled plots from a repeated measures study implemented on the Hoosier National Forest (HNF) in southern Indiana in 1988 to investigate the influence of site and seedling physical attributes on height growth and establishment success of oak species (Quercus spp.) reproduction in stands regenerated by the clearcut method. Before harvest, an array of physical attributes were documented for individual stems of advance reproduction. Across all surveys, the same characteristics were remeasured in years 6, 12, and 23 for all reproduction types (advance reproduction, stump sprouts, and new seedlings). In order to characterize topo-edaphic conditions, soil samples were collected and analyzed in 2011, and slope aspect, slope percent, and slope position were measured in the field. Random Forest (RF) analysis was used to determine the best physical and environmental predictors of height growth for oak species and their competitors in developing stands. Overall, advance reproduction of oak species fared poorly following harvests. Sprout-origin oak stems proved stronger competitors in developing stands, although their abundance relative to competing species was quite low. Advance and sprout origin maple (Acer spp.) stems, along with new seedlings of black cherry (Prunus serotina Ehrh.) and yellow-poplar (Liriodendron tulipifera L.), quickly overtopped oak advance reproduction and established dominance in the developing canopy. The height of stems during prior sampling periods was the best overall predictor of stem height in subsequent sampling periods. Species was also an important predictor of stem height. Comparatively, environmental variables were poor predictors of height growth of individual stems throughout the study, although more mesic aspects, greater cation exchange capacity, and greater soil magnesium saturation were associated with greater height of non-sprout origin stems from species groups other than oak or hickory in year 6. Our results suggest that overstory removal has driven stand demographics towards species favored by infrequent large-scale disturbance events such as clearcutting. Without post-harvest treatments to control competitors, oak regeneration on more mesic sites is unlikely to recruit into developing stands.

Ungulate browsing limits forest regeneration on many reforestation and restoration sites. Silviculture can be used to mitigate the effects of ungulate damage by promoting rapid early growth of planted seedlings, but benefits may depend upon site characteristics and ungulate browse pressure. We studied the interactions among browsing by white-tailed deer (Odocoileus virginianus), use of genetically select seed sources, controlled-release fertilization (CRF) at planting, and site type (harvest openings and plantations) in a nine-year hardwood forest regeneration study. The experiment consisted of paired deer exclosure and control plots, with fertilization and seed source, established at two reforested clearcut sites and three afforested agricultural field sites in Indiana, USA. Our objectives were to examine treatment effects on growth (height and diameter), survival, and stem quality of four temperate deciduous hardwood species (northern red oak, white oak, black walnut, and black cherry). For all species, fencing had the greatest significant positive influence on survival (non-fenced: 50–72%, fenced: 71–75% by year 8) and growth (81–178% greater height and 90–167% greater diameter by year 8), as well as stem quality ratings. Fencing also increased (by 50–78%) the probability that black cherry and black walnut at afforested sites (as well as northern red oak at both site types) would reach free-to-grow status by year 5. We observed gains in height and diameter from CRF only during the first three years for fenced black cherry (11% greater height and 14% greater diameter in year 3), and for white oak regardless of fencing (13% greater height and 10% greater diameter in year 3). Genetically select seed sources had the greatest and most consistent growth benefit for black walnut (81% greater height and 50% greater diameter by year 8). Early growth was improved in genetically select P. serotina vs. non-select sources (11% greater height in year 3) but differences faded by the fifth growing season, while superior growth of genetically select Q. rubra began to manifest only after year 5 (16% greater height 21% greater diameter by year 8). In addition, select northern red oaks had an 8% greater probability of reaching free-to-grow status by year 5 and black walnuts at afforested sites had a 13% greater probability of reaching free-to-grow status. Without protection from herbivory, genetically improved sources did not realize their full potential for enhanced growth. Our results from this nine-year-long hardwood plantation experiment confirm that without browse protection, additional silvicultural treatments are unlikely to improve regeneration performance.

The displacement damage induced in W and W-5 wt.% Re and W-5 wt.% Ta alloys by 2 MeV W+ irradiation to doses 3.3 × 1017-2.5 × 1019 W+/m2 at temperatures ranging from 300 to 750 °C has been characterised by transmission electron microscopy. An automated sizing and counting approach based on Image J (a Java-based image processing programme developed at the National Institutes of Health) [1] has been performed for all near-bulk irradiation data. In all cases the damage comprised dislocation loops, mostly of interstitial type, with Burgers vectors b = 1/2〈1 1 1〉 (>60%) and b = 〈1 0 0〉. The diameters of loops did not exceed 20 nm with most being ≤6 nm diameter. The loop number density varied between 1022 and 1023 loops/m3. With increasing irradiation temperature, the loop size distributions shifted towards larger sizes, and there was a substantial decrease in loop number densities. The damage microstructure was less sensitive to dose than to temperature. Under the same irradiation conditions, loop number densities in the W-Re and W-Ta alloys were higher than in pure W but loops were smaller. In grains with normals close to z = 〈0 0 1〉, loop strings developed in pure W at temperatures ≥500 °C and doses ≥1.2 dpa, but such strings were not observed in the W-Re or W-Ta alloys. However, in other grain orientations complex structures appeared in all materials and dense dislocation networks formed at higher doses.

Storm events that increase flow rates can disturb sediments and produce overland runoff in watersheds with animal agriculture, and, thus, can increase surface water concentrations of fecal bacteria and risk to public health. We tested the hypothesis that strategically designed and placed ponds in watersheds with animal agriculture would attenuate downstream fluxes of fecal bacteria. We measured concentrations and fluxes of fecal indicator bacteria (commensal Escherichia coli and fecal enterococci) and manure pathogens (Salmonella and E. coli 0157:H7) in in- and outflows of Bishop Pond in the Southern Piedmont of Georgia during three storm events and in- and outflow concentrations and fluxes of fecal indicator bacteria at Ponds A and C in the Coastal Plain of Georgia during two storm events. Mean concentrations and fluxes of fecal indicator bacteria associated with pond in- and outflow during hydrograph rise, peak, fall, and 5-days after peak flow at Bishop Pond were significantly greater than their mean base flow concentrations and fluxes. In storm flow Bishop Pond significantly reduced the outflow concentrations and fluxes of fecal indicator bacteria compared with corresponding inflow measurements. Unlike fecal indicator bacteria, Bishop Pond appeared not to reduce outflow concentrations and fluxes of Salmonella or E. coli 0157:H7. At Ponds A and C in the Coastal Plain mean in- and outflow concentrations and fluxes of the fecal indicator bacteria associated with the hydrograph rise and peak flows of the storms were not different. Bishop Pond, with a length to width ratio of 3.3, attenuated downstream fluxes of fecal bacteria. In contrast, Ponds A and C were not effective at reducing downstream fluxes of fecal bacteria under storm flow conditions. The ineffectiveness of Ponds A and C may be attributed to their having length to width ratios of 1.2 and 2.5, respectively, both of which are below the minimum for effective pond performance. Our results indicated that in the humid Southeast an appropriately placed and configured pond in watersheds with animal agriculture can reduce storm flow loads of fecal indicator bacteria but not necessarily pathogenic E. coli 0157:H7.

Defect microstructures formed in ion-irradiated metals, for example iron or tungsten, often exhibit patterns of spatially ordered nano-scale dislocation loops. We show that such ordered dislocation loop structures may form spontaneously as a result of Brownian motion of loops, biased by the angular-dependent elastic interaction between the loops. Patterns of spatially ordered loops form once the local density of loops produced by ion irradiation exceeds a critical threshold value., 6 pages, 5 figures

Deleterious effects of overabundant deer populations within natural areas have been well documented and hunting programs have been initiated to control populations and facilitate the recovery of vegetation communities. However, few studies have examined whether recovery has occurred following sustained hunting. Hunting was initiated during the 1990s to reduce overabundant deer populations in Indiana state parks. In 2010, we resampled 108 plots established in 1996/97 across 15 state parks and five historically-hunted reference areas to quantify changes in herbaceous-layer vegetation. Species cover was measured along three, 10 m line transects nested within each plot. Data were pooled for all parks and reference areas. We calculated species richness (S), evenness (E), and Shannon-Weiner diversity (H′) in 1996/97 and 2010. Compositional changes between sample intervals and contemporary composition across environmental gradients were examined using nonmetric multidimensional scaling (NMS). We observed greater increases in herbaceous-layer cover in parks than in reference areas. S and H′ increased significantly in parks, but not reference areas. NMS ordinations revealed unidirectional changes in species composition between parks and their respective reference areas with the composition of parks becoming more similar to that of reference areas through time. Park size, cumulative deer harvest, initial deer abundance, and recent average of harvest/hunter effort were significantly correlated ( p r | > 0.5 for at least one axis). Browse-sensitive functional groups increased in cover while that of exotic species decreased. Changes were most pronounced for tree seedlings, which displayed a sixfold increase in cover within parks between sample intervals. These results suggest that hunting has allowed recovery of degraded vegetation communities.

Home-based telemental health (TMH) treatments have the potential to address current and future health needs of military service members, veterans, and their families, especially for those who live in rural or underserved areas. The use of home-based TMH treatments to address the behavioral health care needs of U.S. military healthcare beneficiaries is not presently considered standard of care in the Military Health System. The feasibility, safety, and clinical efficacy of home-based TMH treatments must be established before broad dissemination of home-based treatment programs can be implemented. This paper describes the design, methodology, and protocol of a clinical trial that compares in-office to home-based Behavioral Activation for Depression (BATD) treatment delivered via web-based video technology for service members and veterans with depression. This grant funded three-year randomized clinical trial is being conducted at the National Center for Telehealth and Technology at Joint-base Lewis-McChord and at the Portland VA Medical Center. Best practice recommendations regarding the implementation of in-home telehealth in the military setting as well as the cultural and contextual factors of providing in-home care to active duty and veteran military populations are also discussed.

Georgia farmers are increasing preemergence applications of soil residual herbicides to control glyphosate resistant weeds. To improve efficacy these herbicides are often activated by post-application irrigation. Broiler litter is commonly applied to fields before these herbicides. The herbicide wetting-in practice increases surface soil water content and may increase runoff and transport of broiler litter borne fecal bacteria into surface waters during subsequent storm events. Our objective was to determine differences in loads of fecal bacteria, Escherichia coli and Salmonella spp., in runoff from conventional tillage (CT) and no-till (NT) systems after herbicides were watered into an Ultisol fertilized with broiler litter. On replicated 6 m 2 -plots ( n = 3) simulated rainfall was applied for 70 min with composite runoff samples collected every 5 min and analyzed for E. coli and Salmonella spp. Although total runoff volume from the CT plots was significantly greater than from NT plots, no significant differences in total load of E. coli and Salmonella or the percent of total loads of E. coli and Salmonella recovered in runoff between tillage systems were observed. Total percentage of Salmonella recovered in runoff from both tillage systems was, however, four log 10 orders of magnitude greater than the percentage of E. coli that was recovered. Difference in percentage recovered between the fecal indicator bacterium, E. coli , and the pathogen, Salmonella , underscores an apparent difference in hydrologic transport characteristics of these two fecal bacteria and casts doubts on the efficacy of E. coli as an indicator of risk to public health.

Widespread outbreaks of the mountain pine beetle (Dendroctonus ponderosae Hopkins) in the lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) forests of North America have produced stands with significant levels of recent tree mortality. The needle foliage from recently attacked trees typically turns red within one to two years of attack indicating successful colonization by the beetle and tree death. Attempts to model crown fire potential in these stands have assumed that the moisture content of dead foliage responds similarly to changes in air temperature and relative humidity as other fine, dead surface fuels. However, this assumption has not been verified. In this exploratory study we sampled the moisture content of dead foliage on an hourly basis through two different diurnal cycles during the fire season and compared the results to measurements of 10-h fuel moisture indicator sticks and predictions made from models used to estimate dead fuel moisture in the USA, Canada, and Australia. The observed degree of variation in dead foliar moisture content was small (6.9-14.5%) with a mean value of ~10%. All existing models performed poorly, but measurements of 10-h fuel moisture and a modified version of an existing model where timelags were extended to ~20-h had the best fit to the data. The results from our study suggest that the dead foliage on attacked trees does not respond similarly to changing environmental conditions as other fine, dead surface fuels as has been assumed. This in turn has important implications for wildland fire suppression operations, including firefighter safety, and in modeling fire behavior, and solicits the need for further research. Diurnal changes in foliage moisture of MPB-attacked trees are presented.Moisture content of red needles displays little variability across the diurnal cycle.Common models of dead fuel moisture are not appropriate.A modified model and 10-h fuel moisture measurements had the best fit to the data.

Salmonella and Campylobacter prevalence in stream networks of the Satilla River Basin (SRB) were monitored monthly from August 2007 to August 2009 to study relationships between these pathogens and land use, presence of poultry houses and wastewater treatment plant (WWTP) discharge. Salmonella and Campylobacter were detected at all 10 stream sites and the three sites at the sole wastewater treatment plant (WWTP) in the study area. In all, 43% (129/299) and 62% (96/156) of samples were positive for Salmonella and Campylobacter , respectively, with detection frequency increasing in downstream sites with more poultry production and influence of WWTP discharge. Both Salmonella and Campylobacter detection frequencies were positively associated with the number of poultry houses in the subwatersheds, but agricultural land use as a proportion of the watershed was not a significant predictor of either pathogen. Fecal indicator bacterial levels were assessed and evaluated for their ability to predict the presence of pathogens. Of those examined, enterococci was most predictive; of the 129 samples positive for Salmonella , 88% (113/129) were detected when enterococci were above EPA single sample threshold (61 CFU 100 ml -1 ); and of the 96 samples positive for Campylobacter , 90% (86/96) were detected when enterococci levels exceeded this level. Comparatively, Escherichia coli concentrations were above EPA single sample thresholds in 38% (49/129) of the positive Salmonella samples. Detection of the pathogens throughout the watershed indicated that there was potential for waterborne transmission especially in downstream areas that were more likely to have recreational users.

Because of the devastation caused by the combined impacts of the balsam woolly adelgid ( Adelges piceae ; BWA, a non-native insect) and chronic acid deposition, Picea-Abies (spruce-fir) forests are one of the most threatened vegetation communities in North America. Endemic Abies fraseri (Fraser fir), the dominant overstory species in these forests, has experienced near complete overstory mortality as result of the adelgid. Observed forest regeneration patterns suggest high spatial variability, with dense patches of Rubus spp. (blackberry), A. fraseri , and deciduous regeneration repeating across the landscape. To quantify the spatial variability and density of A. fraseri , Picea rubens (red spruce), and deciduous regeneration in these forests, we sampled 60 randomly selected plots within Picea-Abies forests of Great Smoky Mountains National Park (GSMNP). As a measure of local variability in regeneration, we used regeneration density within 30 1 × 1 m subplots per plot to calculate a coefficient of within-plot variation for each species. Despite the impacts of the BWA and chronic acid deposition, A. fraseri remained an important component of southern Appalachian Picea-Abies forests at elevations above 1750 m. Density of A. fraseri in all size classes was associated with time since disturbance by BWA infestation. On plots where A. fraseri regeneration occurred, its local variability (among 30 subplots) was significantly greater than that of P. rubens or deciduous species. Regression models attributed this local-scale variability in A. fraseri regeneration to the influence of elevation, Rubus spp. cover, B-horizon nitrogen concentration, and O-horizon calcium to aluminum ratio. We propose that co-occurring gradients of BWA-induced mortality and acid deposition have created patches of increased light and nitrogen availability, which have increased competition from ruderal species such as Rubus spp. Additionally, our results suggest that high soil aluminum content relative to calcium may exclude A. fraseri from certain locations, further contributing to the local variability of A. fraseri regeneration.

Among emerging adult populations, the increasingly prevalent use of online social media, such as Facebook, and its relationship to individual personality traits and interpersonal relationships are of growing interest to researchers. The current study sought to investigate how attachment style, personality traits based on the Five Factor Model, and self-esteem were related to perceptions of interpersonal competency and Facebook use. Using data collected from 463 emerging adults in college, we conducted three hierarchical multiple linear regression models which suggested that (a) extraversion was positively related to Facebook use, (b) attachment style, extraversion, agreeableness, and openness were positively related to two aspects of interpersonal competency, and (c) Facebook use was negatively related to competence with initiating interpersonal relationships. Future directions for research and practical implications are also discussed.

Anthropogenic deposition of sulfur (S) and nitrogen (N) contributes substantially to soil acidity in some forest regions and hence studies have focused on modeling and quantifying depositions in landscapes. The resulting acidity can change the soil chemical balance, nutrient availability, microbial communities, and at a broader scale, ecosystem functioning. In this study, a 16S PCR-DGGE (polymerase chain reaction-denaturing gradient gel electrophoresis) approach was used to measure the bacterial diversity and identify the dominant bacterial species along a soil acidity gradient in high elevation spruce–fir forests of Great Smoky Mountains National Park (GSMNP). Sample sites were selected based upon modeled S deposition class (6–14, 15–23, 23–32, and 33–41 kg ha −1 ). Collected soils were analyzed for pH, C, N, Ca, Al, S, CEC, and base saturation. Average soil pH in the O, A, and B horizons were 3.6, 3.6 and 3.9, respectively. Modeled S deposition was found to be an unreliable predictor of soil S content as well as most other soil chemical properties. DGGE profiles of bacterial partial 16S rRNA genes revealed minor differences in bacterial diversity while communities were similar, dominated by members of phylum Actinobacteria, Acidobacteria, Planctomycetes, Proteobacteria, and Chloroflexi . Dominance of acidophilic bacterial species, often found in highly acidic environment such as acid-mine drainage and sphagnum bogs, suggests that the poorly buffered soils that are endemic to southern Appalachian spruce–fir forests are saturated with acidity. Our results suggest that stricter air quality standards have not resulted in shift to less acid-tolerant bacteria.

In the Southeastern Coastal Plain (USA) farmers with access to irrigation commonly water in herbicides following their preemergence application to improve efficacy of the herbicide. This practice increases near surface soil water content and may promote increased runoff during subsequent storm events. The objective of our study was to determine differences in P and N runoff from conventional tillage (CT) and no tillage (NT) systems when herbicides were watered into loamy sand Ultisols fertilized with broiler litter. Simulated rain with variable intensity was applied for 70 min with runoff samples collected every 5 min and analyzed for total P and N, PO 4 3− , NH 4 + and NO 3 − . Results indicated the no-tillage treatment lost significantly more PO 4 3− and NH 4 + than the conventional tillage treatment. However, total P and N and NO 3 − runoff losses were significantly less in the no-tillage treatment. The proportion of total P and N leached through NT residues was 5.6% and 22% of the P and N applied as broiler litter, and the proportion of total P and N in runoff was 0.8% and 1.2% of the P and N applied in broiler litter. Overall 3.4 times more N and 2.7 more P were lost in runoff from the CT treatments than for the NT treatments. Reduced tillage was found to reduce N and P losses when combined with watering-in of surface applied broiler litter.

Declining forest health attributed to associations between extensive bark beetle-caused tree mortality, accumulations of hazardous fuels, wildfire, and climate change have catalyzed changes in forest health and wildfire protection policies of land management agencies. These changes subsequently prompted research to investigate the extent to which bark beetle-altered fuel complexes affect fire behavior. Although not yet rigorously quantified, the results of the investigations, in addition to a growing body of operational experience, indicate that predictable changes in surface, ladder and canopy fuel character- istics do occur over the course of a bark beetle rotation. Input of these changes in fuel characteristics into conventional fire behavior modeling systems can readily provide predictions of potential fire behavior, including the likelihood of crowning. However, several factors limit the direct application of these mod- eling systems in their current form and consequently, they may largely under predict fire potential in such stands. This presents a concern where extreme fire behavior involving both crowning and spotting coupled with flammable fuel conditions can pose serious challenges to incident management and threa- ten the safety of firefighters and the general public alike. In this paper, we review the nature and char- acteristics of bark beetle-altered fuel complexes in the conifer forests of the Interior West and the challenges of understanding the effects on extreme fire behavior, including the initiation and spread of crown fires. We also discuss how emerging fire management plans in the U.S. have begun to integrate wildfire management and other forest health objectives with the specific goal of achieving biodiversity and ecosystem resiliency while simultaneously reducing the existence of hazardous fuel complexes.

Herbivores exert a strong influence on the species composition and richness of plant communities, but the magnitude of their effect on belowground communities remains poorly understood. While an increasing number of studies acknowledge the importance of documenting belowground effects of herbivores, very few of these evaluate variation in the strength of the response from aboveground to belowground communities. Our study documents the long-term consequences of sustained deer herbivory for plant and arthropod communities adjacent to 15 exclosures that have been in place since 1996. We hypothesized that herbivory would alter the composition and diversity of communities, but the strength of the effects of herbivory would weaken from plants, to leaf-litter invertebrates, and to belowground microarthropod communities. First, we found that herbivory negatively impacted plant seedling and sapling abundance and performance, reduced the abundance of ants and the taxonomic richness of arthropods in the litter layer and reduced the richness of soil microarthropod communities. Second, in contrast to our hypothesis, the magnitude of effect size did not vary among trophic levels, indicating that effects of deer herbivory cascade from plants to the leaf-litter and soil arthropod communities with equal strength. While much recent research has focused on how specific traits of plants may mediate the effects of herbivory on associated species, our results suggest that indirect effects of herbivory might influence many components of belowground communities.

Animal agriculture in watersheds produces manure bacteria that may contaminate surface waters and put public health at risk. We measured fecal indicator bacteria (commensal Escherichia coli and fecal enterococci) and manure pathogens (Salmonella and E. coli 0157:H7), and physical-chemical parameters in pond inflow, within pond, pond outflow, and pond sediments in three ponds in agricultural watersheds. Bishop Pond with perennial inflow and outflow is located in the Piedmont, and Ponds A and C with ephemeral inflow and outflow in the Coastal Plain of Georgia. Bromide and chloride tracer experiments at Bishop Pond reflected a residence time much greater than that estimated by two models, and indicated that complete mixing within Bishop Pond was never obtained. The long residence time meant that fecal bacteria were exposed to solar UV-radiation and microbial predation. At Bishop Pond outflow concentrations of fecal indicator bacteria were significantly less than inflow concentrations; such was not observed at Ponds A and C. Both Salmonella and E. coli 0157:H7 were measured when concomitant concentrations of commensal E. coli were below the criterion for surface water impairment indicating problems with the effectiveness of indicator organisms. Bishop Pond improved down stream water quality; whereas, Ponds A and C with ephemeral inflow and outflow and possibly greater nutrient concentrations within the two ponds appeared to be less effective in improving down stream water quality.

We used pre- and post-burn fire effects data from six prescribed burns to examine post-burn threshold effects of stand structure (understory density, overstory density, shrub cover, duff depth, and total fuel load) on the regeneration of yellow pine (Pinus subgenus Diploxylon) seedlings and cover of herbaceous vegetation in six prescribed-fire management units located within western Great Smoky Mountains National Park (GSMNP) in east Tennessee, USA. We also evaluated the utility of the Keetch–Byram Drought Index (KBDI) as a predictor of post-burn stand and fuel conditions by comparing post-burn stand variables for different ranges of KBDI (23–78; more wet, and 328–368; more dry). We found that yellow pine seedlings were effectively absent in post-burn forests until overstory density was reduced over 40%, understory density was reduced over 80%, and post-burn shrub cover was 10% or less. We also observed that a reduction in total fuels of 60% and a post-burn duff layer depth of less than four cm were required for successful regeneration of yellow pine. Total herbaceous species cover exhibited near identical responses with increased cover following an 80% reduction in understory density and a post-burn duff depth of less than 4 cm. We observed strong positive relationships between high KBDI values and burn severity, changes in forest structure, reductions in fuels, and post-burn yellow pine reproduction. We observed continuous recruitment of yellow pine seedlings 5 years after fire in high KBDI burns while low KBDI burns showed little change in yellow pine density through time. An intense outbreak of the southern pine beetle (SPB; Dendroctonus frontalis) occurred within 2 years of our high KBDI burns and reduced shading resulting from overstory mortality likely enhanced the survival of yellow pine seedlings. The results of this study provide targets for the application of prescribed fire to restore yellow pine in the southern Appalachians. Continued research and monitoring will help determine how prescribed fire can best be applied in combination with other disturbance agents such as SPB to perpetuate yellow pine forests.

Forest degradation in protected areas has been monitored around the world with remote sensing data, but degradation processes undetectable by widely used satellite sensors have been largely overlooked. Increased human pressures and socioeconomic development make forest protection more challenging, particularly for forest ecosystems that lie across national borders because of the differences in national socioeconomic policies and conditions within them. Here with Landsat data, Google Earth images, and field observations, we show that, in two adjacent biosphere reserves across the border of China and North Korea, over one half of primary forest landscapes have been deteriorated by exploitive uses, including seed harvesting and systematic logging. The combined effects of detectable and hidden degradation pro- cesses have further damaged forest ecosystems in the core areas in the two biosphere reserves, threaten- ing sustainable biodiversity conservation in the region. It is urgent to develop cross-border collaborative conservation strategies that can help combat both detectable and hidden degradation processes at a regional scale.

Exotic pests and pathogens can cause extensive mortality of native species resulting in cascading effects within an ecosystem. As ecosystems lose species to exotic enemies, ecosystem function may be disrupted if the ecological roles are not filled by the remaining species. To illustrate this concept, this paper examines the impacts of an exotic fungus (Discula dectructiva) on flowering dogwood (Cornus florida), historically a common understory tree species in eastern U.S. hardwood forests. Recent studies indicate that dogwood plays an important role in the health and ecological integrity of forest ecosystems throughout the eastern U.S. by increasing the availability of calcium in the biota-rich surface horizons of forest soils. However, Discula destructiva causes a disease, dogwood anthracnose, which can rapidly kill dogwood trees. This paper also illustrates how past fire has increased dogwood density and improved tree health in areas infected with anthracnose, suggesting that prescribed fire may offer a tool for land managers to maintain dogwood as a component in eastern U.S. hardwood forests by shifting the “ideal” disturbance regime of this previously fire-intolerant species.

We investigated the population age structure and spatial patterning of a common understory perennial, Trillium erectum var. album, in primary and post-logging secondary (industrially logged in the early 1900s) cove forests of the southern Appalachian Mountains. Within each of 8 T. erectum populations (4 in primary forest and 4 in secondary forest), we mapped the locations of all T. erectum plants in a 10 m × 10 m plot located within the center of each population. We recorded the height and life stage of each plant and excavated a randomly selected subset for age determination. Trillium erectum populations in primary forests displayed a somewhat stronger and more consistent spatial structure than those found in secondary forests. However, aside from being on-average younger due to a higher concentration of juveniles, age structures of secondary forest populations were similar to those of primary forests and both forest types had similar maximum plant ages. Our results, when considered with the life history of the species, suggest that logging did not eliminate T. erectum from secondary forests. Rather, residual plants and patches of plants that survived logging provided the propagules needed to expand and reestablish populations following logging. This relatively rapid recovery stands in stark contrast to the slow recovery observed by others in post-agricultural secondary forest. When considered in the context of other studies of post-disturbance recovery in secondary forests, our results suggest that the full history of a site must be carefully considered when examining the impacts of disturbance on forest perennial herbs.

The evolution of radiation damage under heavy-ion irradiation in thin foils of pure bcc Fe has been investigated by simulation and experiment. Simulations showed that vacancy loops are about as mobile as interstitial loops, and can be lost to the surface of a foil. Consistent with this, in situ real-time dynamic observations of the damage evolution showed that loops, many of which are believed to be of vacancy nature, were mobile and were often lost during irradiation. Atomistic simulations of vacancy defects in Fe showed that spherical voids, rather than vacancy loops, represent the lowest energy configurations for clusters of vacancies of any size. The simulations also indicated that the stability of loops strongly varies depending on their size. Closed loops above a critical diameter (∼2 nm) are highly metastable due to the difficulty of their transformation into voids. The greater stability of voids explains why the loop yield in Fe and other ferritic materials is very low.

Soil microbial communities under three agricultural management systems (conventionally tilled cropland, hayed pasture, and grazed pasture) and two fertilizer systems (inorganic fertilizer and poultry litter) were compared to that of a w150-y-old forest near Watkinsville, Georgia. Both 16S rRNA gene clone libraries and phospholipid fatty acid (PLFA) analyses indicated that the structure and composition of bacterial communities in the forest soil were significantly different than in the agricultural soils. Within the agricultural soils, the effect of fertilizer amendment on bacterial communities was more dramatic than either land use or season. Fertilizer amendment altered the abundance of more bacterial groups throughout the agricultural soils. In addition, the changes in the composition of bacterial groups were more pronounced in cropland than in pastures. There was much less seasonal variation between the soil libraries. Community-level differences were associated with differences in soil pH, mineralizable carbon and nitrogen, and extractable nutrients. Bacterial community diversity exhibited a complex relationship with the land use intensity in these agro-ecosystems. The pastures had the highest bacterial diversity and could be characterized as having an intermediate degree of intervention compared to low intervention in forest and high intervention in cropland. Changes in bacterial diversity could be attributed to the abundance of a few operational taxonomic units (OTUs). The microdiversity of abundant OTUs in both forest and cropland was consistent with an increase in abundance of many phenotypically similar species rather than a single species for each OTU. Soil microbial communities were significantly altered by long-term agricultural management systems, especially fertilizer amendment, and these results provide a basis for promoting conservation agricultural systems.

Cornus florida L. has long been hypothesized to increase calcium (Ca) mineralization in eastern forests because of its high foliar Ca concentration, quick foliar decomposition rate, and abundance. This hypothesis, however, has not been proven. We sampled 68 10 m × 10 m plots in two forest types, cove hardwood and oak hardwood, to quantify the influence of C. florida density on initial exchangeable Ca and Ca mineralization in the mineral soil and forest floor. C. florida density was classified into three levels in each forest type (zero = 0 stems ha −1 , low = 200–300 stems ha −1 , and high ≥600 stems ha −1 ). We found significantly greater levels of initial exchangeable Ca in high density plots than in low density plots in both forest types in both the forest floor and mineral soil ( P C. florida plots (cove hardwood, high density 3.3 g Ca kg −1 year −1 versus zero density 0.6 g Ca kg −1 year −1 , P = 0.04 and oak hardwood, high density 2.4 g Ca kg −1 year −1 versus zero density 1.1 g Ca kg −1 year −1 , P = 0.09). These results indicate that the loss of C. florida due to dogwood anthracnose has altered the Ca cycle and may negatively affect the health of eastern hardwood forests.

The application of poultry litter to agricultural fields can provide plant nutrients for crops and forage production, but fecal bacteria and the sex hormones estradiol and testosterone are components of litter that can be detrimental to the environment. Our objective was to determine if applications of poultry litter to small watersheds would contribute to the load of fecal bacteria and sex hormones to soil and runoff. We, therefore, investigated the fate and transport of fecal bacteria, estradiol and testosterone from surface applied poultry litter to four small watersheds. Poultry litter was applied to meet the nitrogen requirements of pearl millet (Pennisetum glaucum L.) in 2000 and grain sorghum [Sorgham bicolor (L.) Moench] in 2001. Neither Salmonella nor Campylobacter were detected in the litter but the fecal indicator bacteria were. The average load of total coliforms,Escherichia coli, and fecal enterococci applied with the litter was 12.2, 11.9, and 12.7 log10 cells ha(−1), respectively. The average load of estradiol and testosterone was 3.1 and 0.09 mg ha(-1), respectively.Runoff events first occurred seven months after the first litter application in 2000, and three weeks after the second application in 2001.Only for the 25 July 2001 runoff event three weeks after the second litter application, were the concentrations of total coliforms, E. coli,and fecal enterococci in runoff greater than background concentrations which were on average 5.2, 1.1, and 2.9 log10 MPN 100 ml(−1),respectively [corrected]. Average background levels of total coliforms, fecal enterococci,and E. coli in surface soil were 8.2, 7.9, and 3.5 log (10) cells kg(−1) soil. At the rate of litter application the concentrations of estradiol and testosterone in the litter did not appear to impact the background levels in the soil and runoff. Because concentrations of sex hormones in litter from other broiler operations are known to be greater than in the litter we applied, further study on the connection between concentrations of sex hormones in poultry litter and operational practices is recommended.

A novel technique for the quantification of the iron content of copper precipitates in ferritic steels is presented. Energy-filtered (EF) imaging has been used to extract elemental maps with high spatial resolution. These maps contain enough information to attempt the quantification of the signal produced by the precipitates when either a line profile is measured across them or the whole image signal is integrated. Assumptions such as sphericity of the precipitates and composition variations are discussed. Special attention to the assessment of drift on the information extracted from EF images has been taken. Minimum detectability and optimum acquisition conditions are discussed. © 2005 Elsevier B.V. All rights reserved.

Chronic herbivory by white-tailed deer (Odocoileus virginianus Zimmerman) can have profound impacts on the function and structure of forest ecosystems. We examined the combined influence of intense herbivory associated with a deer population eruption and chronic herbivory by the post eruption population on the spring flora of Cades Cove, Great Smoky Mountains National Park. During the 1970s the deer population reached a peak of 43 deer per km2, from which it has slowly declined in recent decades. To examine the influence of intense herbivory, we compared the abundance and flowering rates of early flowering plants in Cades Cove to a nearby reference site with similar bedrock geology, vegetation, and disturbance history but contrasting history of deer abundance. Our results suggest that significant changes (p ⩽ 0.05) in the diversity, evenness, and species richness of the spring flora occurred during the eruptive phase. Trillium spp. and other liliaceous species appeared to be disproportionately impacted. Comparisons between control and exclosure plots established after the deer population eruption indicate that recovery has been largely restricted to species that were able to persist under intense herbivory. These species have increased in number in exclosures, suggesting continued impacts by deer on the plant community outside the exclosures. Little to no recolonization by browse sensitive species was observed. Consequently, to restore the natural diversity of early flowering plants once present in Cades Cove, active restoration may be necessary in addition to maintaining deer densities below current levels.

We examined the influence of topography and anthropogenic disturbance associated with European settlement in the southern Appalachian Mountains of Tennessee on contemporary distributions of coarse woody debris in western Great Smoky Mountains National Park. Coarse woody debris (≥10 cm diameter) was sampled on 63 permanent 20 m × 50 m plots, which were classified into one of five anthropogenic disturbance history classes based on published accounts: concentrated settlement, corporate logging, diffuse disturbance, diffuse disturbance with large residual trees present, or primary forest (no documented history of anthropogenic disturbance). Former concentrated settlement areas contained significantly less down deadwood (DDW) than areas with a history of less intense disturbance ( P 3 ha −1 ) and highly decayed (39.2 ± 16.2 m 3 ha −1 ) DDW than areas with a history of anthropogenic disturbance prior to Park Service acquisition in the 1930s (87.1 ± 15.5 and 21.1 ± 5.3 m 3 ha −1 , respectively). Large diameter DDW was most abundant in primary forests (90.1 ± 46.0 m 3 ha −1 ) and least common in forests with a history of concentrated settlement (7.3 ± 3.0 m 3 ha −1 ). Within a disturbance history class, the greatest levels of DDW were found on more mesic sites and/or higher elevations. Our results suggest that areas with a history of anthropogenic disturbance may require well over a century to recover coarse woody debris distributions found in areas of primary forest.

There has been significant interest in the empirical performance of the Purchasing Power Parity (PPP) hypothesis. Initial studies were, in general, unfavorable for PPP. These results led researchers into two directions. One branch of the literature employed price data for a limited range or goods (e.g., fruits or clothing). A second branch has reevaluated the performance of PPP with more powerful methods. In this paper we combine these two branches of the literature. We use consumer price sub-indices data and recently developed panel cointegration techniques to test weak PPP. Our results are suggestive that the failure of PPP can be attributed to inclusion of non-traded goods in the overall index.

Rhizobial symbionts were isolated from the surface (0–0.5 M) and phreatic (3.9–5.0 M) root environments of a mature mesquite woodland in the Sonoran Desert of Southern California, and from variable depths (0–12 m) of non-phreatic mesquite ecosystems in the Chihuahuan Desert of New Mexico. They were tested for their ability to tolerate high salinity, and respire NO 3 − as mechanisms of free-living survival. Sixteen of 25 isolates were grown in yeast-extract mannitol (YEM) broth at NaCl concentrations of 2 (basal concentration), 100, 300, 500 and 600 mM, and their specific growth rates, cell dry weight and lag times were determined. Twenty of the 25 isolates were also grown in YEM broth under anaerobic conditions with or without 10 mM KNO 3 . Three categories of NaCl salinity responses were observed: (1) eight isolates showed decreased specific growth rates at NaCl concentrations of 100, 300 and 500 mM, but they nevertheless remained viable at 500 mM NaCl concentration; (2) the specific growth rate of six isolates increased significantly at 100 and 300 mM NaCl; and (3) specific growth rates of two isolates were significantly greater than the base-rate at all concentrations of NaCl. Five of 11 of the Bradyrhizobium isolates tested respired NO 3 − , but showed no growth. Seven Rhizobium isolates, three from the deep (3.9–5 m) phreatic rhizobial community, and four from the surface community denitrified NO 3 − but only the isolates from the phreatic community displayed anaerobic growth. Long-term interactions between rhizobial and bradyrhizobial communities and the surface and phreatic root environments of the mature Sonoran Desert mesquite woodland appear to have selected for strains of NO 3 − respiring rhizobia, general salt tolerance of both rhizobial and bradyrhizobial symbionts, and strains of weak facultative halophilic bradyrhizobia. These survival characteristics of mesquite rhizobia may be important regarding mesquite's establishment and long-term productivity in marginal desert soils, and may provide novel types of rhizobia for food crops growing in harsh environments.

This study examined climate factors associated with major avalanche years on the Wasatch Plateau in south-central Utah. Dendro-ecological methods were used to date the occurrence of avalanche events in 16 avalanche paths during the period of 1928–1996. From this information, the probability of avalanche occurrence in each path for each year was calculated, and used to distinguish major avalanche years. The resulting avalanche chronologies indicated that 14 large widespread avalanche events occurred on the Wasatch Plateau between 1928 and 1996. Logistic regression and classification tree analyses were used to examine relationships between climate variables and the probability of major avalanche years. The results of logistic regression analysis showed that mean January snowfall was significantly related (p

The interaction between soil types, temperature, and soil water potential may have differential effects on the survival of Cryptosporidium parvum oocysts in the terrestrial environment. We examined the effects of three soil types (a silty clay loam, silt loam, and loamy sand), three temperatures (4, 20, and 30 °C), and three soil water potentials (−0.033, −0.5 and −1.5 MPa) on the inactivation kinetics of oocysts. Sentinel chambers were filled with air-dried and sieved soil, brought to the appropriate soil water potential, and inoculated with 2×106 freshly purified oocysts. The inoculated chambers were buried in the same bulk soil at the appropriate water potentials and incubated at one of the three temperatures. Triplicate chambers were removed from the bulk soil on days 0, 22, 43, 84 and 156. Sentinel oocysts were extracted, and assayed for potential infectivity by the dye permeability method. Oocysts suspended in sterile distilled water and incubated with the sentinel chambers were used as controls for the effect of temperature. The soil water potentials investigated did not affect oocyst inactivation at any temperature or with any of the three soil types. Rates of oocyst inactivation increased significantly between 4 and 20 °C, but not between 20 and 30 °C with the exception of oocysts incubated in the silty clay loam. Oocyst survival appeared to be significantly greater in the silt loam soil than in the two other soil types when incubated at 20 °C; and at 30 °C oocyst survival was significantly less in the silt clay loam than in the other two soil types. Rates of sentinel oocyst inactivation at all three soil water potentials were significantly lower than the control oocysts in water at the three test temperatures. Thus oocyst survival in soil was not affected by the water potentials between −0.033 and −1.5 MPa; it was affected by soil texture; but temperature appeared to be the factor most affecting oocyst survival. In the critical ambient range of temperature in temperate climates oocysts may survive for months in agricultural soil, and pose a threat to surface waters.

Standardization activities in the United States for continuous fiber-reinforced ceramic composites (CFCCs) are reviewed. This brief review focuses on the development of test standards by subcommittee C28.07 of the American Society for Testing and Materials (ASTM) on the drafting of a section of a design code for ceramic and ceramic matrix composite components as part of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code, and on the development of a set of volumes on ceramic matrix composites for Military Handbook 17 on composites. The participation of the US in the international harmonization of standards for CFCCs is also reviewed.

Between 1993 and 1995 we sampled woody vegetation (seedling, sapling, and overstory) on 150 plots in Fagus–Acer saccharum/Arisaema Mesic Slope and Quercus alba–Acer saccharum/Parthenocissus Dry-Mesic Slope forests to determine how species composition and diversity of these forests responded to management. We sampled four different treatments, clear-cuts, group selections, single tree selections and uncut 80–100 year-old reference stands. Results suggest that clear-cut and group selection openings greatly increase the importance of Liridodendron tulpifera L. (tulip popular) on both Ecological Landtype Phases (ELTP's, dry and mesic slopes). Single tree selection has accelerated succession by greatly increasing the importance of Acer saccharum Marsh (sugar maple). Quercus sp. were more important in clear-cuts and group selections on dry-mesic slopes than on mesic slopes. The seedling and sapling layers of clear-cuts, group selections and single tree selections on both ELTP's were dominated by A. saccharum, suggesting this species will eventually dominate both ELTP's in the absence of disturbance. Single tree selection openings on both ELTP's had much lower overstory species richness and diversity than clear-cuts, group selections, or reference stands. This suggests that the predominant use of single tree selection harvest will greatly reduce woody species richness and diversity across a forest landscape. A mixture of selection and larger clear-cut openings may be needed to maintain the woody species diversity of forest landscapes in the Central Hardwood Region by creating condition that allow regeneration of both tolerant and intolerant species.

Grain boundary-interface dihedral angles in Al2O3/SiC and Al2O3/TiN nanocomposites have been measured from TEM micrographs, and the ratio of the particle/matrix interfacial energy γi to the alumina grain boundary energy γgb has been calculated on the basis of an energy balance condition. The average ratio, γi/γgb, was found to be 1.21 for Al2O3/SiC and 0.80 for Al2O3/TiN. These results, together with estimates of surface energies, have been used to estimate interfacial fracture energies. It is found that the interfacial fracture energy between SiC and alumina is more than twice the alumina grain boundary fracture energy, i.e. SiC nanoparticles strengthen grain boundaries. The dominant factor in this result is the greater surface energy of SiC compared with Al2O3. Despite the higher surface energy of TiN and the lower γi/γgb ratio for Al2O3/TiN, it is found experimentally that TiN particles weaken grain boundaries instead of strengthening them. The detrimental factor is believed to be the formation of TiO2 at the interfaces. The weakening is consistent with a lower interfacial fracture energy. The present work indicates the importance of interfacial properties, which should not be ignored in modelling.

We empirically assess the importance of two sources of real exchange rate movements. In models where PPP holds only among traded goods, real exchange rate variation results from relative price movements within countries. An alternative explanation relies on hysteretic price-setting and nominal exchange rate changes. Using disaggregated price data from 11 OECD nations, we find some support for the non-traded goods models. For example, prices of haircuts in Canada and the United States are unrelated in the long run. We find stronger evidence to support models that emphasize sticky prices, transportation costs, or other impediments to frictionless trade.

The effects of rate-dependent inelastic deformation were observed during tensile static, dynamic, and cyclic fatigue testing of a hot-isotatically pressed, monolithic, polycrystalline silicon nitride in ambient air at temperatures of 1150, 1260 and 1370°C. Constant stresses in static fatigue ranged from 50 to 300 MPa. Stress rates in dynamic fatigue ranged from 10−4 to 101 MPa/s. Waveforms in cyclic fatigue included trapezoid, triangle and sine at a stress ratio, R, of 0.1, frequencies of 0.1 and 10 Hz, and maximum stresses ranging from 75 to 325 MPa. At 1150°C, all fatigue results showed a similar slow crack growth failure mechanism with no separate cyclic fatigue mechanism. However, at 1260 and 1370°C the failure mechanism was multi-faceted. For both temperatures, the failure in static fatigue was dominated by the accumulation of diffusion-controlled creep cavities. In dynamic fatigue, the inelastic deformation exhibited by non-linear stress-strain curves supported the conclusion of failure by slow crack growth alone at high stress rates and by a mixture of slow crack growth and creep damage at low stress rates. Under cyclic loading, ‘enhanced’ times to failure, attributed to viscous rate effects, occurred regardless of waveform or frequency. The stress rate was related to the stress at the onset to non-linearity, σ0, indicating a quasi-endurance limit below which cyclic fatigue had little ‘enhancing’ effect. Creep compliance relations indicated non-linear viscoelastic (or viscoplastic) behavior, leading to speculation on the role of this behavior in producing the ‘enhanced’ cyclic fatigue resistance.

A critical review is given of the conventional imaging techniques used in transmission electron microscopy to characterise radiation damage microstructures. Particular emphasis is given to the limitations of some of these techniques. The techniques are illustrated by examples.