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An increased awareness of sustainability among the population leads, from an industrial point of view, to efforts to act more ecologically as well as to the aim for lower production costs and an increased efficiency. With this in mind, a new process has been developed for foaming without blowing agents in rotational molding. Process related air inclusions in the polymer melt are expanded to form the cell structure by means of vacuum application. In the presented study, the influence of different particle sizes as well as the arising potential of deploying microgranules in the otherwise powder-based process is investigated with regard to the resulting foam cells. The results confirm that particle size and form greatly influence the existence and size of air inclusions in the polymer melt. It could be proven that these differences, caused by the particle characteristics, propagate during the foaming process and lead to different cell morphologies in the resultant foam. Furthermore, it is indicated that qualitative predictions of the resulting cell dimensions can be made on the basis of bulk density measurements and the analysis of the sintering behaviour of the initial particles.

In Yellowstone National Park (YNP), Ospreys (Pandion haliaetus) feed primarily on cutthroat trout (Oncorhynchus clarki bouvieri) and cutthroat trout represent approximately 23% of prey consumed by Bald Eagles (Haliaeetus leucocephalus) during the breeding season (Swenson 1978, Journal of Wildlife Management 42:87–90; Swenson et al. 1986, Wildlife Monographs 95:3–46). The introduction of exotic lake trout (Salvelinus namaycush) to Yellowstone Lake during the late 1980s caused substantial declines in populations of cutthroat trout. Historically, more than half of all breeding pairs of Ospreys and Bald Eagles in YNP have nested near and foraged at Yellowstone Lake and the decline in cutthroat trout numbers may affect rates of reproduction for these two species. We studied the relationship between an index of cutthroat trout abundance and spring weather on Osprey (1987–2009) and Bald Eagle (1987–2007) reproduction. We documented steep declines in an index of cutthroat trout abundance, Osprey producti...

Intracortical bone remodeling is persistent throughout life, leading to age related increases in osteon population density (OPD). Intracortical porosity also increases with age in many mammals including humans, contributing to bone fragility and fracture risk. Unbalanced bone resorption and formation during disuse (e.g., physical inactivity) also increases intracortical porosity. In contrast, hibernating bears are a naturally occurring model for the prevention of both age-related and disuse osteoporoses. Intracortical bone remodeling is decreased during hibernation, but resorption and formation remain balanced. Black bears spend 0.25-7 months in hibernation annually depending on climate and food availability. We found longer hibernating bears demonstrate lower OPD and higher cortical bone mineralization than bears with shorter hibernation durations, but we surprisingly found longer hibernating bears had higher intracortical porosity. However, bears from three different latitudes showed age-related decreases in intracortical porosity, indicating that regardless of hibernation duration, black bears do not show the disuse- or age-related increases in intracortical porosity which is typical of other animals. This ability to prevent increases in intracortical porosity likely contributes to their ability to maintain bone strength during prolonged periods of physical inactivity and throughout life. Improving our understanding of the unique bone metabolism in hibernating bears will potentially increase our ability to develop treatments for age- and disuse-related osteoporoses in humans.

Anthropogenic changes in landscape composition or configuration have the potential to increase the abundance of generalist species, often resulting in cascading effects on other trophic levels and ecosystem function. The selection or utilization of individual patches of habitat, however, may vary in both time and space, as a result of patch and landscape attributes as well as dynamic abiotic factors (i.e., snowfall). We hypothesized that the use of high-quality habitat would be most strongly influenced by snow at local scales and by composition and the configuration of the landscape at greater spatial scales. To test this, we examined white-tailed deer ( Odocoileus virginianus (Zimmermann, 1780)) selection of eastern hemlock ( Tsuga canadensis (L.) Carrière) patches as winter habitat over a 3-year period. Patch-level attributes were poor predictors of patch use in areas with strong gradients in abiotic factors relevant to the energetics of movement or forage acquisition. Additionally, heterogeneity in the greater landscape (3000 m radius buffer) served to increase use, while homogeneity appeared to decrease use. Our results suggest that interactions between deer migratory behavior, interannual variation in winter severity, and landscape context might provide spatial and temporal refugia for hemlock regeneration; a better understanding of which could aide conservation and restoration.

To assess and improve existing monitoring protocols for sharp-tailed grouse (Tympanuchus phasianellus) in the eastern Upper Peninsula of Michigan, we used data from 58 radio-collared grouse (46 M, 12 F) monitored within 3 openland landscape types: a xeric, conifer-dominated site, a wetland-dominated site, and a site dominated by low-intensity agriculture. We used lek counts and radio telemetry to determine lek attendance rates, factors affecting lek attendance rates, lek fidelity, and inter-sexual variation in these parameters. Our analysis indicated lek attendance varied with respect to sex of bird, day of year, time after sunrise, and wind speed. Peak male lek attendance rates exceeded those of females by up to 40%, and peak lekking activity for both males and females occurred during the second and third weeks of April. Male lekking activity occurred earlier and was sustained longer than that of females. Lekking activity was negatively related to time of day and wind speed. We observed strong lek fidelity as radio-collared birds attended a primary lek 94% of the time, indicating a low probability of multiple counting of individual birds. We also proposed a method to adjust lek count data for the probability that birds are on a lek during lek counts. Our proposed method can be used by researchers and managers to improve estimates of the number of birds attending a lek by reducing the negative bias associated with observed counts.

Osteoarthritis (OA) is a widespread degenerative disease of skeletal joints and is often associated with senescence in vertebrates. OA commonly results from excessive or abnormal mechanical loading of weight-bearing joints ('wear-and-tear'), arising from heavy long-term use or specific injuries; yet, in the absence of injury, the aetiology of OA remains obscure. We show that poor nutritional conditions experienced by moose (Alces alces) early in life are linked to greater prevalence of OA during senescence as well as reduced life expectancy. Moreover, we also found a negative relationship between kill rate by wolves (Canis lupus) and prevalence of OA, suggesting a potential connection between senescence of prey and the population ecology of predator-prey systems. This association between OA and early malnutrition also provides a basis for explaining the observation in anthropology that OA became more prevalent in native Americans as their diet become poorer - the result of relying more on corn and agriculture and less on hunting and gathering.

Disuse typically causes an imbalance in bone formation and bone resorption, leading to losses of cortical and trabecular bone. In contrast, bears maintain balanced intracortical remodeling and prevent cortical bone loss during disuse (hibernation). Trabecular bone, however, is more detrimentally affected than cortical bone in other animal models of disuse. Here we investigated the effects of hibernation on bone remodeling, architectural properties, and mineral density of grizzly bear (Ursus arctos horribilis) and black bear (Ursus americanus) trabecular bone in several skeletal locations. There were no differences in bone volume fraction or tissue mineral density between hibernating and active bears or between pre- and post-hibernation bears in the ilium, distal femur, or calcaneus. Though indices of cellular activity level (mineral apposition rate, osteoid thickness) decreased, trabecular bone resorption and formation indices remained balanced in hibernating grizzly bears. These data suggest that bears prevent bone loss during disuse by maintaining a balance between bone formation and bone resorption, which consequently preserves bone structure and strength. Further investigation of bone metabolism in hibernating bears may lead to the translation of mechanisms preventing disuse induced bone loss in bears into novel treatments for osteoporosis.

Disuse typically uncouples bone formation from resorption, leading to bone loss which compromises bone mechanical properties and increases the risk of bone fracture. Previous studies suggest that bears can prevent bone loss during long periods of disuse (hibernation), but small sample sizes have limited the conclusions that can be drawn regarding the effects of hibernation on bone structure and strength in bears. Here we quantified the effects of hibernation on structural, mineral, and mechanical properties of black bear (Ursus americanus) cortical bone by studying femurs from large groups of male and female bears (with wide age ranges) killed during pre-hibernation (fall) and post-hibernation (spring) periods. Bone properties that are affected by body mass (e.g. bone geometrical properties) tended to be larger in male compared to female bears. There were no differences (p > 0.226) in bone structure, mineral content, or mechanical properties between fall and spring bears. Bone geometrical properties differed by less than 5% and bone mechanical properties differed by less than 10% between fall and spring bears. Porosity (fall: 5.5 ± 2.2%, spring: 4.8 ± 1.6%) and ash fraction (fall: 0.694 ± 0.011, spring: 0.696 ± 0.010) also showed no change (p > 0.304) between seasons. Statistical power was high (>72%) for these analyses. Furthermore, bone geometrical properties and ash fraction (a measure of mineral content) increased with age and porosity decreased with age. These results support the idea that bears possess a biological mechanism to prevent disuse and age-related osteoporoses.

Black bears (Ursus americanus) may not develop disuse osteoporosis during long periods of disuse (i.e. hibernation) because they may be able to maintain bone formation. Previously, we found that cortical bone bending strength was not compromised with age in black bears tibias, despite annual periods of disuse. Here we showed that cortical bone tensile strength (166–198 MPa) also does not decrease with age (2–14 years) in black bear tibias. There were also no significant age-related changes in cortical bone porosity in black bear tibias. It is likely that the ability of black bears to maintain bone formation during hibernation keeps bone porosity low (2.3–8.6%) with aging, notwithstanding annual periods of disuse. This low porosity likely preserves ultimate stress with aging. Female bears give birth and nurse during hibernation; however, we found no significant differences between male and female tensile material properties, mineral content, or porosity. Our findings support the idea that black bears, which hibernate 5–7 months annually, have evolved biological mechanisms to mitigate the adverse effects of disuse on bone porosity and strength.

Gray wolves (Canis lupus) in upper Michigan, USA, have been monitored since 1991 when breeding activity in mainland Michigan was documented for the first time since 1954. Based on winter track counts, the mean annual rate of increase in abundance was 19% from 1995 to 2002, with the population reaching an estimated 278 animals in 2002. Our objectives were to (1) increase the efficiency of wolf management in Michigan by evaluating alternative and less extensive sampling approaches for population estimation, and (2) evaluate habitat for wolves based on occupancy after a decade of recovery. For the first analysis, we created 22 discrete sampling units that cover upper Michigan, and we evaluated abundance estimates based on various sampling plans using known distribution and populations from the 2000–2002 winter track surveys. We evaluated each plan based on the precision, bias, and confidence interval coverage. A random sampling plan with regression estimator returned the most precise estimates, but ...

Identifying scales of pattern in ecological systems and coupling patterns to processes that create them are ongoing challenges. We examined the utility of three techniques (lacunarity, spectral, and wavelet analysis) for detecting scales of pattern of ecological data. We compared the information obtained using these methods for four datasets, including: surface temperature across space (linear transect), surface temperature across time, understory plant diversity across space (linear transect), and a simulated series of known structure. For temperature and plant diversity across the transect, we expected to find dominant scales of pattern of approximately 220 m and, for plant diversity scales of pattern of >450 m, corresponding to management activities on the study landscapes. For temperature across time, we predicted a dominant scale of 24 h. The simulated data included a sine wave with a known period of 9.9 units, an edge at approximately 30 units, and a random component. The different analyses provided unique but complementary information. Lacunarity and spectral analyses were most consistent with each other across datasets, both indicating a dominant scale of pattern at 400–500 m (coarser than expected) for the transect temperature series, a lack of dominant scale in the pattern of understory diversity, and scales of pattern at 1.8–5.1 and 8.5–11.1 units (≈wavelength) for the simulated data series. Spectral analysis best approximated an expected, 24 h period in the temporal temperature series. Wavelet variance detected finer scales of pattern (240 m) in transect temperature and suggested patterns in plant diversity at scales of 460 and 1100 m. By retaining locational information, only the wavelet transform and associated position variance detected the abrupt edge in the simulated data series. Wavelet analysis also emphasized variability, even within cyclic phenomena, not identified by spectral or lacunarity analyses, and suggested hierarchical structure in the pattern of understory plant diversity. The appropriate technique for assessing scales of pattern depends on the type of data available, the question being asked, and the detail of information desired. This comparison highlighted the importance of: (1) using multiple techniques to examine scales of pattern in ecological data; (2) interpreting analysis results in concert with examination and ecological knowledge of the original data; and (3) utilizing results to direct subsequent descriptive and experimental examination of features or processes inducing scales of pattern.

The increasing popularity of brown bear (Ursus arctos) viewing at Brooks River in Katmai National Park, Alaska has resulted in overcrowded facilities, increasing bear-human conflicts, displacement of bears from important habitats, and degradation of cultural resources. To partially address these issues, the National Park Service (NPS) constructed a 300-m-long elevated boardwalk with interconnected viewing platforms in August 2000. To determine what effects the new structures might have on individual bears, we observed bear movements and behaviors before and after construction. We used direct observations and motion-detection cameras to construct temporal-spatial profiles of bear activity. Although bear numbers were similar (59 bears in 2000 and 56 bears in 2001) and bear activity within the greater Brooks River area did not differ (P = 0.62, n = 29) between the 2 years of this study, trail crossings in the vicinity of the new structures decreased 78% (7,436 crossings in 2000 and 1,646 crossings i...

Wolf (Canis lupus) impacts on prey are a central post-wolf-reintroduction issue in the greater Yellowstone ecosystem (GYE) of the western United States. Further, estimates of wolf kill rates, used to understand these impacts, can be biased due to unrecovered kills. In Yellowstone National Park (YNP), visibility of wolves allowed us to combine independent aerial and ground observations and use a double-count method to estimate the probability of recovering kills. We consequently used these data to adjust estimates of wolf kill rates. We conducted monitoring annually from 1995 to 2000 during 2 30-day periods in early (15 Nov–14 Dec) and late winter (Mar). Estimated recovery rates of wolf kills for ground and aerial crews were 50% and 45%, respectively, although we determined that this varied by location (distance from road) and possibly age (calf or adult) of the kill. The estimated combined recovery rate was 73%. Estimated wolf kill rates were higher in late winter (2.2 kills/wolf/month) compared ...

We analyzed the leadership behavior of breeding and nonbreeding gray wolves (Canis lupus) in three packs during winter in 1997–1999. Scent-marking, frontal leadership (time and frequency in the lead while traveling), initiation of activity, and nonfrontal leadership were recorded during 499 h of ground-based observations in Yellowstone National Park. All observed scent-marking (N = 158) was done by breeding wolves, primarily dominant individuals. Dominant breeding pairs provided most leadership, consistent with a trend in social mammals for leadership to correlate with dominance. Dominant breeding wolves led traveling packs during 64% of recorded behavior bouts (N = 591) and 71% of observed travel time (N = 64 h). During travel, breeding males and females led packs approximately equally, which probably reflects high parental investment by both breeding male and female wolves. Newly initiated behaviors (N = 104) were prompted almost 3 times more often by dominant breeders (70%) than by nonbreeders (25%). Dominant breeding females initiated pack activities almost 4 times more often than subordinate breeding females (30 vs. 8 times). Although one subordinate breeding female led more often than individual nonbreeders in one pack in one season, more commonly this was not the case. In 12 cases breeding wolves exhibited nonfrontal leadership. Among subordinate wolves, leadership behavior was observed in subordinate breeding females and other individuals just prior to their dispersal from natal packs. Subordinate wolves were more often found leading packs that were large and contained many subordinate adults.

The instrumented falling weight perforation impact behavior of coinjection-molded multipolypropylene sandwich plaques of various compositions having a β-phase isotactic polypropylene (PP) homopolymer core was studied at room temperature and respectively. The results were compared with those achieved on injection-molded monomaterial plaques of α- and β-polymorphs. It was found that the coinjection strategy is beneficial only if the skin-forming α-phase PP has a markedly lower molecular weight than the β-nucleated core PP. Sandwich plaques with PP copolymer skins exhibited an outstanding perforation impact resistance. The coinjection strategy for extrusion grade PPs yielded no improvement. Perforation impact at showed a prominent toughness reduction of the multipolypropylene plaques which became comparable with that of the monolayer plaques.

Summary Understanding landscape organization across scales is vital for determining the impacts of management and retaining structurally and functionally diverse ecosystems. We studied the relationships of a functional variable, decomposition, to microclimatic, vegetative and structural features at multiple scales in two distinct landscapes of northern Wisconsin, USA. We hoped to elucidate any characteristic resolutions of structure-process relationships on these landscapes, and to determine the validity of extrapolation of structure-process associations across scales and management regimes. We used a combination of ANOVA, wavelet, canonical discriminant, and correlation analyses and asked specifically whether: 1) specific combinations of microclimatic, structural, and vegetative features were consistently associated with differences in decomposition among management zones along transects (i.e., within landscapes); and 2) factors influencing decomposition were consistent among resolutions of analysis and depths within and between landscapes. Decomposition was greater on the pine barrens than the small block transect and greater at 4 cm depth than at the surface for both landscapes. Significant differences in decomposition occurred among management patches for both transects and depths, except 4 cm along the pine barrens. In general decomposition was faster for patch types with greater overstory cover at 1 cm (both transects) and lower at 4 cm (small block). Canonical discriminant analysis also separated management patches by overstory cover for both transects. Secondary vectors also separated patches along both transects by microclimate, independent from overstory effects on those variables. Dominant resolutions in the patterns of decomposition differed between transects and depths: 80 m (pine barrens, 1 cm); 500 m (pine barrens 4 cm); 160 m (small block, 1 cm); and 750 m (small block, 4 cm). At the 1 cm depth, the strongest correlations of wavelet transforms of decomposition with structural, microclimatic, and vegetation variables often differed in resolution from those dominant in the decomposition patterns. At the 4 cm depths, many of the strongest correlations occurred at the maximum resolutions examined. Although many important correlates differed between transects and depths within a transect, there were some consistencies. On both transects, surface and soil temperatures were strongly correlated (|r| > 0.40) with decomposition; soil temperatures were stronger correlates along the small block. The direction of association between decomposition and temperatures changed with depth, being negative at 1 cm and positive at 4 cm for both transects. Overstory was an important correlate (|r| > 0.50) for 3 of 4 transect-depth combinations. On both transects, correlations between decomposition and overstory peaked at different resolutions and were different signs (positive at 1 cm and negative at 4 cm) for the two decomposition depths. Along the pine barrens but not the small block, there were two peaks of resolutions of correlation that appeared consistently across variables. Thus, correlates of decomposition changed with scale as well as depth and management regime. This suggests that factors other than management may still be maintaining decomposition patterns on the landscapes. Further, patterns in and relationships to process variables should be examined at multiple scales to develop a comprehensive understanding of the mechanisms driving functional heterogeneity. Das Verstandnis der Landschaftsorganisation ist entscheidend fur die Bestimmung der Auswirkungen von Management und fur den Erhalt von strukturell und funktionell diversen Okosystemen. Wir untersuchten die Beziehungen zwischen einer funktionellen Variablen, der Zersetzung, und mikroklimatischen, Vegetations- und Struktureigenschaften auf multiplen Skalen in zwei unterschiedlichen Landschaften im nordlichen Wisconsin, USA. Wir hofften, charakteristische Losungen fur Struktur-Prozes-Beziehungen in den Landschaften aufzuklaren, sowie die Gultigkeit von Extrapolationen von Struktur-Prozess-Beziehungen uber Skalen und Management-Regimes zu bestimmen. Wir nutzten eine Kombination von ANOVA, “wavelet”-, kanonischer Diskriminanz- und Korrelationsanalysen und fragten uns insbesondere: (1) ob spezielle Kombinationen von mikroklimatischen, strukturellen und Vegetationseigenschaften durchweg mit Unterschieden in der Zersetzung zwischen den Managementzonen entlang der Transekte (d.h. innerhalb der Landschaften) verbunden waren; und (2) ob es bei verschiedenen Auflosungen der Analysen und Tiefen innerhalb und zwischen den Landschaften durchgangige Faktoren waren, die die Zersetzung beeinflusten. Die Zersetzung war in den beiden Landschaften in den Kieferodlandern groser als in den “small block”-Transekten; und in 4 cm Tiefe groser als an der Oberflache. Signifikante Unterschiede in der Zersetzung traten zwischen “Management-patches” sowohl fur die Transekte als auch die Tiefen auf; mit Ausnahme der 4 cm Tiefe in den Kieferodlandern. Im Allgemeinen war die Zersetzung in den “patch”-Typen mit groserer Oberholz-Deckung (overstorey) bei 1 cm schneller (beide Transekte), und bei 4 cm geringer (“small block”-Transekt). Die Kanonische Diskriminanzanalyse trennte ebenfalls gemanagte “patches” nach der Oberholz-Deckung bei beiden Transekten. Sekundare Vektoren) trennten ebenfalls “patches” nach dem Mikroklima, unabhangig vom Oberholz-Einfluss auf diese Variablen. Die dominanten Auflosungen in den Mustern der Zersetzung unterschieden sich zwischen den Transekten und Tiefen: 80 m (Kieferodlander, 1cm), 500 m (Kieferodlander, 4 cm), 160 m (“small block”-Transekt, 1 cm) und 750 m (“small block”-Transekt, 4 cm). Bei 1 cm Tiefe unterschieden sich die starksten Korrelationen der “wavelet”-Transformation der Zersetzung mit strukturellen, mikroklimatischen und Vegetationsvariablen haufig in der Auflosung von denen, die dominant in den Zersetzungsmustern waren. Bei 4 cm Tiefe fanden sich viele der starksten Korrelationen bei der maximalen betrachteten Auflosung. Obwohl sich viele, wichtige korrelierende Variablen (correlates) zwischen den Transekten und den Tiefen innerhalb eines Transektes unterschieden, gab es einige Gemeinsamkeiten. Auf beiden Transekten waren Oberflachen- und Bodentemperatur stark mit der Zersetzung korreliert (|r| > 0.40); die Bodentemperaturen waren die starker korrelierenden Variablen entlang des “small block”-Transekts. Die Richtung der Beziehung zwischen der Zersetzung und der Temperatur anderte sich mit der Tiefe und war negativ in 1 cm und positiv in 4 cm Tiefe bei beiden Transekten. Oberholz war eine wichtige korrelierende Variable (|r| > 0.50) bei 3 von 4 Transekt-Tiefen-Kombinationen. Bei beiden Transekten erreichten die Korrelationen zwischen Zersetzung und Oberholz ihren Hohepunkt bei verschiedenen Auflosungen und zeigten unterschiedliche Vorzeichen fur die beiden Zersetzungstiefen (positiv bei 1 cm, negativ bei 4 cm Tiefe). Entlang der Kieferodlander, jedoch nicht entlang des “small block”-Transekts, gab es zwei Hohepunkte der Auflosung der Korrelation, die bei den Variablen durchweg auftraten. Somit anderten sich die korrelierenden Variablen sowohl mit der Skala als auch mit der Tiefe und dem Management-Regime. Das legt nahe, dass andere Faktoren als das Management die Zersetzungs-Muster in den Landschaften aufrechterhalten. Weiterhin sollten Muster in und Beziehungen zwischen den Prozes-Variablen auf multiplen Skalen untersucht werden, um ein umfassendes Verstandnis der Mechanismen zu entwickeln, die die funktionelle Heterogenitat vorantreiben.

In this study, Advanced Very High Resolution Radiometer (AVHRR) remote sensing reflectance ( Rrs), imagery from 1987‐1993 is used to study changes in water clarity before and after zebra mussels (Dreissena polymorpha) were discovered in Saginaw Bay, Lake Huron. Spatial and temporal trends in the data indicate distinct and persistent increases in water clarity in the inner bay after the first large recruitment of zebra mussels in the fall of 1991. The pre-Dreissena imagery show that turbidity in the inner bay was influenced by the Saginaw River discharge in spring, biological production (plankton) in summer, and wind-driven resuspension in fall, with highest turbidity in spring and fall. Spatial patterns in the post- Dreissena images were more similar regardless of season, with low reflectances in the shallow regions of the inner bay where zebra mussel densities were highest. A regression model based on point data from 24 sampling stations over the 7-yr period indicates that reflectances varied significantly by site and zebra mussel densities, as well as seasonally. Trends in observed and predicted values of reflectances followed similar patterns at each station—highest values were found during 1991 and lowest during 1992 at all stations, with slightly higher Rrs in 1993 compared to 1992. Whereas AVHRR Rrs highlight the value of historical imagery for reconstructing seasonal and interannual turbidity patterns in near-shore waters, a new generation of operational ocean color satellites, such as SeaWiFS (Sea-viewing Wide Field-of-view Sensor) and the newly launched MODIS (moderate resolution imaging spectroradiometer), now provide for routine monitoring of important biological and physical processes from space.

Landscape management requires an understanding of the distribution of habitat patches in space and time. Regions of edge influence can form dominant components of both managed and naturally patchy ecosystems. However, the boundaries of these regions are spatially and temporally dynamic. Further, areas of edge influence can be defined by either biotic (e.g. overstory cover) vs. abiotic (e.g. microclimate) characteristics, or structural (e.g. vegetation height) vs. functional (e.g. decomposition rates) features. Edges defined by different characteristics are not always concordant; the degree of spatial concurrence varies with time. Thus, edge effects are difficult to generalize or quantify across a landscape. We examined temperature at eight times of the day across the edge between a clearing and a 50-year-old pine stand. We used simple, nonlinear equations to model and predict temperature gradients across this edge over time. The depth of edge influence (DEI) on temperature varied from 0 to 40 m, depending on the patch type and time of day. Two equations were required to model adequately (r 2 >0.50) patterns of temperature at all eight times of the day. Model fit was best at night (r 2 a0.97) and lowest in the afternoon (r 2 a0.50). Parameters for the models could be predicted from local, reference weather conditions. However, these linear relationships varied among parameters and with time of day (0.29r 2 0.99). Model validation was weak, with mean absolute percent error >10% for all day-time combinations. The models tended to underestimate DEI for both patch types, though edge depth was more accurately predicted in the closed-canopy stand than in the clearing. The difference between observed and predicted edge effects was highest at midday in the clearing and during the morning under closed canopy. The models predicted the location of peak temperature and the slope of temperature change (i.e. pattern of temperature variation) across the edge and the range of temperature better than actual values. We suggest that this approach may, therefore, be useful for characterizing edge dynamics if a wider range of local weather conditions could be monitored during initial data collection. The empirical evidence for temporal changes in position and intensity of abiotic edge effects emphasized the need to quantify these dynamics across time and space for sound planning at the landscape scale. # 1999 Elsevier Science B.V. All rights reserved.

Growth of northern red oak (Quercus rubra L.) seedlings in relation to colonization by indigenous ectomycorrhizal (ECM) fungi was studied in oak and pine stands in northern Lower Michigan that were subjected to overstory and understory manipulations. Two stand types (oak and pine), three blocks of each stand type, four canopy cover treatments (clearcut, 25% cover (50% cover in the first year), 75% cover and uncut), and two understory treatments (shrub removal and untreated control) were involved in the experiment. Northern red oak acorns from a common seed source were sown in May 1991 to simulate natural regeneration. Seedling growth and its relation to percent ECM were evaluated for the first two growing seasons. A significantly larger root-collar diameter of northern red oak seedlings was found in pine stands than in oak stands for the first growing season (P < 0.001). However, this difference could not be explained by overall ECM colonization. Seedling growth and ECM colonization were not affected by the shrub removal treatment during the first two growing seasons. In contrast, northern red oak seedling size and weight were strongly influenced by the overstory treatment, with lower levels of canopy cover resulting in larger seedlings. Seedlings had the greatest percent ECM in the partial cover treatment (25-50%) and the lowest percent ECM in the clearcut. After accounting for the effects of canopy cover, the relationship between total biomass of northern red oak seedlings and percent ECM was positively correlated (P = 0.001) during the first growing season and negatively correlated (P = 0.038) during the second growing season. A positive relationship between root/shoot ratio and percent ECM also existed in the first year (P = 0.003) in both oak and pine stands, but only in the oak stands in the second year (P = 0.039). These results indicate that ECM promoted more root development than shoot development, particularly underpartial canopy cover (25%-50%) treatments, where the greatest percent ECM and largest root/shoot ratio were found. Moreover, our results suggest that these partial canopy cover treatments provide a favorable balance between ECM abundance and northern red oak seedling development in both oak and pine stands on intermediate quality sites, and may lead to northern red oak regeneration success on such sites. North. J. Appl. For. 15(4):182-190.

This paper deals with the computation, production and test results of a rotor for brushless dc motors, consisting of two different permanent magnetic materials as well as having three different magnetic field areas. The main advantage of this highly integrated system of low costs is the implementation of two additional magnetic traces for commutation and speed detection into one single unit.

Intracortical bone remodeling is persistent throughout life, leading to age related increases in osteon population density (OPD). Intracortical porosity also increases with age in many mammals including humans, contributing to bone fragility and fracture risk. Unbalanced bone resorption and formation during disuse (e.g., physical inactivity) also increases intracortical porosity. In contrast, hibernating bears are a naturally occurring model for the prevention of both age-related and disuse osteoporoses. Intracortical bone remodeling is decreased during hibernation, but resorption and formation remain balanced. Black bears spend 0.25-7 months in hibernation annually depending on climate and food availability. We found longer hibernating bears demonstrate lower OPD and higher cortical bone mineralization than bears with shorter hibernation durations, but we surprisingly found longer hibernating bears had higher intracortical porosity. However, bears from three different latitudes showed age-related decreases in intracortical porosity, indicating that regardless of hibernation duration, black bears do not show the disuse- or age-related increases in intracortical porosity which is typical of other animals. This ability to prevent increases in intracortical porosity likely contributes to their ability to maintain bone strength during prolonged periods of physical inactivity and throughout life. Improving our understanding of the unique bone metabolism in hibernating bears will potentially increase our ability to develop treatments for age- and disuse-related osteoporoses in humans.

Mental stress elicits a robust and consistent forearm vasodilation, but vascular reactivity in the calf remains inconsistent. It has been reported that calf vascular responses to MS may be sex dependent. Muscle sympathetic nerve activity (MSNA) is an important contributor to calf blood flow (CBF), yet the relations between sex, limb blood flow, and MSNA reactivity to mental stress have not been explored. We hypothesized that mental stress would elicit more dramatic vasodilation of the limbs in women and that this might be explained by reduced MSNA reactivity and/or blunted sympathetic vascular transduction. We measured heart rate (HR), mean arterial pressure (MAP), CBF, calf vascular conductance (CVC), forearm blood flow (FBF), forearm vascular conductance (FVC), and MSNA concurrently in 18 men (age: 23 ± 2 yr) and 16 women (age: 24 ± 2 yr) during 5 min of supine baseline and 5 min of mental stress. Mental stress elicited similar increases in MAP (Δ10 ± 1 vs. Δ11 ± 1 mmHg), HR (Δ16 ± 2 vs. Δ17 ± 2 beats/min), FBF (Δ81 ± 16% vs. Δ83 ± 15%), and FVC (Δ62 ± 13% vs. Δ65 ± 13%) in men and women, respectively. In contrast, CBF (Δ16 ± 8% vs. Δ37 ± 9%, P = 0.036) and CVC (Δ4 ± 7% vs. Δ24 ± 8%, P = 0.036) responses were exaggerated in women compared with men. Changes in FVC were significantly correlated with changes in CVC in women ( r = 0.681, P = 0.004) but not in men. MSNA reactivity to mental stress was not different between men and women; however, changes in CVC were negatively correlated with increases of MSNA in men ( r = −0.411, P = 0.045) but not in women. In conclusion, our data suggest different patterns of calf vascular reactivity to mental stress in men and women that might relate, in part, to altered vascular transduction of MSNA.

Transmitters were implanted in three adult, one yearling, and one kit beaver (Castor canadensis) in northern Minnesota and upper Michigan to determine if core body temperature (Tb) declined in winter. Beaver Tb and activity were automatically recorded from late autumn through early spring. In late October through early November, mean daily Tb of adults was 36.3 °C (range 34.5–37.6 °C), with a mean daily Tb fluctuation of 1.4 °C. From fall to winter adult beaver Tb declined at a mean rate of 0.01 °C/day, and the mean daily winter (17 November – 15 April) Tb was 35.3 °C (range 32.5–38.8 °C). Mean daily winter Tb fluctuation was 2.5 °C. In early March, mean adult daily Tb began increasing at a rate of 0.03 °C/day. Tb and activity were positively correlated, except for the kit beaver, which did not undergo a significant Tb decline during winter. The yearling beaver Tb declined at a slower rate than adult Tb, and its Tb was intermediate between that of the kit and the three adults. Continued body growth in winter in young beavers is probably enhanced by high body temperature. For adult beavers, reduced body temperature in winter may be an adaptation that facilitates survival during extreme resource scarcity.

Bovet claims that Smith et al. (D.W. Smith, R.O. Peterson, T.D. Drummer, and D.S. Sheputis, 1991. Can. J. Zool. 69: 2178–2182) and Dyck and MacArthur (A.P. Dyck and R.A. MacArthur, 1992. Can. J. Zool. 70: 1668–1672) analyzed their data on activity and body temperature of beavers (Castor canadensis) incorrectly because they ignored the likelihood that northern beavers in winter have activity rhythms with periods >24 h. The analysis by Smith et al. was in fact appropriate for demonstrating seasonal changes in body temperature and its correlation with activity. These are important issues because researchers have obtained conflicting results and because seasonal changes in activity and body temperature have implications for colony energetics in the context of food-hoarding behavior and social organization.

Collateral thermal damage and residual char formation have severely limited the use of conventional lasers in the surgical preparation of bony tissue. Thermal damage from lasers can be minimized by selecting a wavelength that is strongly absorbed and by reducing the laser pulse duration. In contrast to the fixed wavelengths and microsecond pulse intervals of conventional lasers, the Vanderbilt free electron laser (FEL) can be set at wavelengths ranging from 2.1 to 9.8 microm, and the pulse duration can be reduced to a series of 1 to 2 picosecond (ps) micropulses delivered in succession over intervals of 4 microsecond macropulses. The purpose of this study was to compare the morphologic and chemical changes induced in the near-surface region of bone following exposure to the FEL at 3.0, 6.1, and 6.45 microm wavelengths. The selected wavelengths coincide with the vibrational modes of proteins and water within bone.Under general anesthesia, laser incisions were made in the tibias of 14 skeletally mature rabbits. Laser parameters included 22.5+/-2.5 mJ/pulse delivered in individual 4 microsecond macropulses at a repetition rate of 30 Hz, focused to 200 microm and 500 microm spot sizes. Laser incisions were made using a computer-assisted surgical program, and control incisions were created with a bone saw. Rabbits were euthanized after the final incision, tibias recovered, and non-decalcified specimens processed for light microscopy. Separate samples were prepared for FTIR (Fourier transform infrared) photoacoustic spectroscopic analysis.The light microscopy sections of the ablation defects created at the differing wavelengths showed similar features, i.e., 2 zones of collateral damage, a zone generally10 mm of extensive thermal damage, and a wider zone of empty lacunae. In comparing treated and untreated surfaces, the spectral differences were limited to a relative decrease in intensity of the amide II and III absorption peaks in all laser-treated surfaces.Spectroscopic and histologic results indicated minimal thermal damage to bone ablated at 3.0, 6.1, and 6.45 microm wavelengths using the FEL (Fourier transform infrared) at the specified parameters. The FTIR photoacoustic spectroscopic results suggest that the char layer is limited to an area less than approximately 6 microm from the surface.

In some line transect surveys, the population of interest consists of groups or clusters of individuals rather than single items. If group size influences the probability of detecting a group, then the observed group size data are size-biased. This can lead to overestimation of the true mean group size and hence could lead to overestimation of the density of individuals. Our method of line transect sampling incorporates group size as a covariate in line transect detection functions. We applied our method to shipboard surveys of sea otter (Enhydra lutris) and to surveys of pellet groups from barren ground caribou (Rangifer tarandus granti). Group size influence varied in the sea otter surveys. Our method of estimation adequately adjusted for size bias when it was present. Estimates of pellet group density were unaffected by significant size bias. J. WILDL. MANAGE. 54(3):511-514 Many factors can influence the detectability of items in line transect and other surveys of biological populations (e.g., Caughley 1974, Bayliss and Giles 1985, Gasaway et al. 1985). A particular problem occurs when the population consists of groups of items, and the size of the group influences its chance of detection (Quinn 1979, Rao et al. 1981, Drummer and McDonald 1987). We illustrate the procedure proposed by Drummer and McDonald (1987) in which group size is used as a covariate in existing line transect detection functions. Note that our method can also be used more generally to adjust estimates of the mean and total of any auxiliary variable that influences detectability in line transect sur

SUMMARY Line transect sampling is used to estimate the number of individuals in a study area. It is usually assumed that the detections of individuals constitute independent events, and that the probability of detecting an item is a function of its perpendicular distance from the transect. However, certain species of plants/animals tend to aggregate, or cluster, thus possibly violating the assumption of independence. Also, larger clusters may tend to have a higher probability of detection, thus distorting the observed probability distribution of cluster sizes. This can cause overestimation of the true population size. A similar problem occurs if the experimenter is using line transect data to estimate the mean and total amount of some attribute of the items, and this attribute influences the item's probability of detection. Bivariate detection functions that incorporate the cluster size, or another attribute, as a covariate are proposed. Estimators of total population size and of the moments of the additional variate are derived using the theory of weighted distributions. An application of the method to a shipboard survey of minke whales is provided. Line transect sampling is traditionally used to estimate the total number of items in a study area. It is usually assumed that the probability of detecting an item is a function of its perpendicular distance from the transect. See Burnham, Anderson, and Laake (1980) for a comprehensive review of line transect estimation procedures. The primary application of the proposed procedure is for the case when the population consists of groups, or clusters, of individuals. In order to estimate the density of individuals per unit area, the experimenter will need an estimate of mean group size. However, if group size influences delectability, the observed mean group size is a biased estimator of the mean. Also, an experimenter may desire to use line transect surveys to estimate some attribute of the items other than their density (number) per unit area. For example, if the item under study is a particular shrub species, the experimenter may require an estimate of the mean height of the plants in the study area. If larger plants have a greater chance of being detected from the transect, then these data are size-biased toward larger plants. Thus, the observed mean height may be a poor estimate of the true mean. The line transect estimator of density that is based solely on the observed distances from the transect to the items may also be biased. It is important to determine whether the additional variable(s) of interest influences an item's probability of detection. If this is the case, then estimates of the characteristics of this variable must be adjusted for the size-biased sampling phenomenon.