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Sample records for grizzly bears electronic

  1. Grizzly bear

    Science.gov (United States)

    Schwartz, C.C.; Miller, S.D.; Haroldson, M.A.; Feldhamer, G.; Thompson, B.; Chapman, J.

    2003-01-01

    The grizzly bear inspires fear, awe, and respect in humans to a degree unmatched by any other North American wild mammal. Like other bear species, it can inflict serious injury and death on humans and sometimes does. Unlike the polar bear (Ursus maritimus) of the sparsely inhabited northern arctic, however, grizzly bears still live in areas visited by crowds of people, where presence of the grizzly remains physically real and emotionally dominant. A hike in the wilderness that includes grizzly bears is different from a stroll in a forest from which grizzly bears have been purged; nighttime conversations around the campfire and dreams in the tent reflect the presence of the great bear. Contributing to the aura of the grizzly bear is the mixture of myth and reality about its ferocity. unpredictable disposition, large size, strength, huge canines, long claws, keen senses, swiftness, and playfulness. They share characteristics with humans such as generalist life history strategies. extended periods of maternal care, and omnivorous diets. These factors capture the human imagination in ways distinct from other North American mammals. Precontact Native American legends reflected the same fascination with the grizzly bear as modern stories and legends (Rockwell 1991).

  2. Eastern slopes grizzly bear project

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-01-01

    The cumulative effects of human activities on the grizzly bears in the central Canadian Rockies are not well known. As a result, a project was initiated in 1994 to address the urgent requirement for accurate scientific information on the habitat and populations of grizzly bears in the area of the Banff National Park and Kananaskis Country. This area is probably the most heavily used and developed area where the grizzly still survives. The information gathered throughout the course of this study will be used to better protect and manage the bears and other sensitive carnivores in the region. Using telemetry, researchers are monitoring 25 grizzly bears which were radio-collared in a 22,000 square-kilometer area in the upper Bow Valley drainage of the eastern Alberta slopes. The researchers involved in the project are working with representatives from Husky Oil and Talisman Energy on the sound development of the Moose Mountain oil and gas field without adversely affecting the grizzly bear population. Information collected over seven years indicated that the grizzly bears have few and infrequent offspring. Using the information gathered so far, the location of the Moose Mountain to Jumping Pound pipeline was carefully selected, since the bears recover very slowly from high mortality, and also considering that the food and cover had already been compromised by the high number of roads, trails and other human activities in the area. The status of the population and habitat of the grizzly bear will be assessed upon the conclusion of the field research phase in 2001. Models will be updated using the data obtained during eight years and will assist in the understanding of complex variables that affect grizzly bears.

  3. Geophagy by yellowstone grizzly bears

    Science.gov (United States)

    Mattson, D.J.; Green, G.I.; Swalley, R.

    1999-01-01

    We documented 12 sites in the Yellowstone ecosystem where grizzly bears (Ursus arctos horribilis) had purposefully consumed soil (an activity known as geophagy). We also documented soil in numerous grizzly bear feces. Geophagy primarily occurred at sites barren of vegetation where surficial geology had been modified by geothermal activity. There was no evidence of ungulate use at most sites. Purposeful consumption of soil by bears peaked first from March to May and again from August to October, synchronous with peaks in consumption of ungulate meat and mushrooms. Geophageous soils were distinguished from ungulate mineral licks and soils in general by exceptionally high concentrations of potassium (K) and high concentrations of magnesium (Mg) and sulphur (S). Our results do not support the hypotheses that bears were consuming soil to detoxify secondary compounds in grazed foliage, as postulated for primates, or to supplement dietary sodium, as known for ungulates. Our results suggest that grizzly bears could have been consuming soil as an anti-diarrheal.

  4. Myrmecophagy by Yellowstone grizzly bears

    Science.gov (United States)

    Mattson, D.J.

    2001-01-01

    I used data collected during a study of radio-marked grizzly bears (Ursus arctos horribilis) in the Yellowstone region from 1977 to 1992 to investigate myrmecophagy by this population. Although generally not an important source of energy for the bears (averaging 8 mm long) nested in logs over small ants (6 mm long) nested under stones. Optimal conditions for consumption of ants occurred on the warmest sites with ample substrate suitable for ant nests. For ants in mounds, this occurred at low elevations at non-forested sites. For ants in logs, this occurred at low elevations or on southerly aspects where there was abundant, large-diameter, well-decomposed woody debris under an open forest canopy. Grizzly bears selected moderately decomposed logs 4a??5 dm in diameter at midpoint. Ants will likely become a more important food for Yellowstone's grizzly bears as currently important foods decline, owing to disease and warming of the regional climate.

  5. Eastern slopes grizzly bear project : project update

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2002-01-01

    This report updates a study to examine the cumulative effects of human activities on the grizzly bears in the central Canadian Rockies. The project was initiated in 1994 to acquire accurate scientific information on the habitat and populations of grizzly bears in the area of the Banff National Park and Kananaskis Country. This area is probably the most heavily used and developed area where the grizzly still survives. The information gathered throughout the course of the study is used to better protect and manage the bears and other sensitive carnivores in the region. Using telemetry, researchers monitored 25 grizzly bears which were radio-collared in a 22,000 square-kilometer area in the upper Bow Valley drainage of the eastern Alberta slopes. The researchers worked with representatives from Husky Oil and Rigel Energy on the development of the Moose Mountain oil and gas field without adversely affecting the grizzly bear population. Information collected over eight years indicates that the grizzly bears have few and infrequent offspring. Using the information gathered thus far, the location of the Moose Mountain to Jumping Pound pipeline was carefully selected, since the bears suffer from high mortality, and the food and cover had already been compromised by the high number of roads, trails and other human activities in the area. The research concluded in November 2001 provides sufficient information to accurately asses the status of the grizzly bear population and habitat. The data will be analyzed and integrated in 2002 into models that reflect the variables affecting grizzly bears and a final report will be published.

  6. North Cascades Grizzly Bear Ecosystem Evaluation

    Data.gov (United States)

    Oak Ridge National Laboratory — We conducted a 6-year evaluation of the North Cascades Grizzly Bear Ecosystem (NCGBE) in north-central Washington to determine the suitability of the area to support...

  7. Yellowstone grizzly bear investigations: Annual report of the Interagency Grizzly Bear Study Team, 2006

    Science.gov (United States)

    Schwartz, Charles C.; Haroldson, Mark A.; West, Karrie K.

    2007-01-01

    The contents of this Annual Report summarize results of monitoring and research from the 2006 field season. The report also contains a summary of nuisance grizzly bear (Ursus arctos horribilis) management actions.

  8. Yellowstone grizzly bear investigations: Annual report of the Interagency Grizzly Bear Study Team, 2001

    Science.gov (United States)

    Schwartz, Charles C.; Haroldson, Mark A.

    2001-01-01

    The contents of this Annual Report summarize results of monitoring and research from the 2001 field season. The report also contains a summary of nuisance grizzly bear (Ursus arctos horribilis) management actions.

  9. The paradigm of grizzly bear restoration in North America

    Science.gov (United States)

    Schwartz, C. C.; Maehr, David S.; Noss, Reed F.; Larkin, J.L.

    2002-01-01

    Grizzly bear restoration and recovery is a controversial, highly politicized process. By 1959, when the Craigheads began their pioneering work on Yellowstone grizzly bears, the species had been reduced to a remnant of its historic range. Prior to the colonization of North America by Europeans, the grizzly lived in relatively pristine habitats with aboriginal Native Americans. As civilization expanded, humans changed the face of the landscape, converting grizzly bear habitat to farms and ranches. People killed grizzlies to protect livestock and eliminate a perceived threat to human safety. In concert, habitat loss and direct human-caused mortality had effectively eliminated the grizzly from 95 percent of its historic range in the conterminous United States by the 1920s (Servheen 1989). Grizzly bear numbers had been reduced nearly 98 percent by 1975 when the species was listed as threatened under the Endangered Species Act (ESA) (USFWS 1993).

  10. Demography of the Yellowstone grizzly bears

    Science.gov (United States)

    Pease, C.M.; Mattson, D.J.

    1999-01-01

    We undertook a demographic analysis of the Yellowstone grizzly bears (Ursus arctos) to identify critical environmental factors controlling grizzly bear vital rates, and thereby to help evaluate the effectiveness of past management and to identify future conservation issues. We concluded that, within the limits of uncertainty implied by the available data and our methods of data analysis, the size of the Yellowstone grizzly bear population changed little from 1975 to 1995. We found that grizzly bear mortality rates are about double in years when the whitebark pine crop fails than in mast years, and that the population probably declines when the crop fails and increases in mast years. Our model suggests that natural variation in whitebark pine crop size over the last two decades explains more of the perceived fluctuations in Yellowstone grizzly population size than do other variables. Our analysis used demographic data from 202 radio-telemetered bears followed between 1975 and 1992 and accounted for whitebark pine (Pinus albicaulis) crop failures during 1993-1995. We used a maximum likelihood method to estimate demographic parameters and used the Akaike Information Criteria to judge the significance of various independent variables. We identified no independent variables correlated with grizzly bear fecundity. In order of importance, we found that grizzly bear mortality rates are correlated with season, whitebark pine crop size (mast vs. nonmast year), sex, management-trapping status (never management-trapped vs. management-trapped once or more), and age. The mortality rate of bears that were management-trapped at least once was almost double that of bears that were never management-trapped, implying a source/sink (i.e., never management-trapped/management-trapped) structure. The rate at which bears move between the source and sink, estimated as the management-trapping rate (h), is critical to estimating the finite rate of increase, I>I?. We quantified h by

  11. Grizzly bear diet shifting on reclaimed mines

    Directory of Open Access Journals (Sweden)

    Bogdan Cristescu

    2015-07-01

    Full Text Available Industrial developments and reclamation change habitat, possibly altering large carnivore food base. We monitored the diet of a low-density population of grizzly bears occupying a landscape with open-pit coal mines in Canada. During 2009–2010 we instrumented 10 bears with GPS radiocollars and compared their feeding on reclaimed coal mines and neighboring Rocky Mountains and their foothills. In addition, we compared our data with historical bear diet for the same population collected in 2001–2003, before extensive mine reclamation occurred. Diet on mines (n=331 scats was dominated by non-native forbs and graminoids, while diets in the Foothills and Mountains consisted primarily of ungulates and Hedysarum spp. roots respectively, showing diet shifting with availability. Field visitation of feeding sites (n=234 GPS relocation clusters also showed that ungulates were the main diet component in the Foothills, whereas on reclaimed mines bears were least carnivorous. These differences illustrate a shift to feeding on non-native forbs while comparisons with historical diet reveal emergence of elk as an important bear food. Food resources on reclaimed mines attract bears from wilderness areas and bears may be more adaptable to landscape change than previously thought. The grizzly bear’s ready use of mines cautions the universal view of this species as umbrella indicative of biodiversity.

  12. Dietary breadth of grizzly bears in the Greater Yellowstone Ecosystem

    Science.gov (United States)

    Gunther, Kerry A.; Shoemaker, Rebecca; Frey, Kevin L.; Haroldson, Mark A.; Cain, Steven L; van Manen, Frank T.; Fortin, Jennifer K.

    2014-01-01

    Grizzly bears (Ursus arctos) in the Greater Yellowstone Ecosystem (GYE) are opportunistic omnivores that eat a great diversity of plant and animal species. Changes in climate may affect regional vegetation, hydrology, insects, and fire regimes, likely influencing the abundance, range, and elevational distribution of the plants and animals consumed by GYE grizzly bears. Determining the dietary breadth of grizzly bears is important to document future changes in food resources and how those changes may affect the nutritional ecology of grizzlies. However, no synthesis exists of all foods consumed by grizzly bears in the GYE. We conducted a review of available literature and compiled a list of species consumed by grizzly bears in the GYE. We documented >266 species within 200 genera from 4 kingdoms, including 175 plant, 37 invertebrate, 34 mammal, 7 fungi, 7 bird, 4 fish, 1 amphibian, and 1 algae species as well as 1 soil type consumed by grizzly bears. The average energy values of the ungulates (6.8 kcal/g), trout (Oncorhynchus spp., 6.1 kcal/g), and small mammals (4.5 kcal/g) eaten by grizzlies were higher than those of the plants (3.0 kcal/g) and invertebrates (2.7 kcal/g) they consumed. The most frequently detected diet items were graminoids, ants (Formicidae), whitebark pine seeds (Pinus albicaulis), clover (Trifolium spp.), and dandelion (Taraxacum spp.). The most consistently used foods on a temporal basis were graminoids, ants, whitebark pine seeds, clover, elk (Cervus elaphus), thistle (Cirsium spp.), and horsetail (Equisetum spp.). Historically, garbage was a significant diet item for grizzlies until refuse dumps were closed. Use of forbs increased after garbage was no longer readily available. The list of foods we compiled will help managers of grizzly bears and their habitat document future changes in grizzly bear food habits and how bears respond to changing food resources.

  13. Grizzly West: A Failed Attempt to Reintroduce Grizzly Bears in the Mountain West

    Directory of Open Access Journals (Sweden)

    Douglas M. Richardson

    2016-05-01

    Full Text Available Reviewed: Grizzly West: A Failed Attempt to Reintroduce Grizzly Bears in the Mountain West. By Michael M. Dax. Lincoln, NE: University of Nebraska Press, 2015. x + 289 pp. US$ 37.50. ISBN 978-0-8032-6673-5.

  14. Effects of exotic species on Yellowstone's grizzly bears

    Science.gov (United States)

    Reinhart, D.P.; Haroldson, Mark A.; Mattson, D.J.; Gunther, Kerry A.

    2001-01-01

    Humans have affected grizzly bears (Ursus arctos horribilis) by direct mortality, competition for space and resources, and introduction of exotic species. Exotic organisms that have affected grizzly bears in the Greater Yellowstone Area include common dandelion (Taraxacum officinale), nonnative clovers (Trifolium spp.), domesticated livestock, bovine brucellosis (Brucella abortus), lake trout (Salvelinus namaycush), and white pine blister rust (Cronartium ribicola). Some bears consume substantial amounts of dandelion and clover. However, these exotic foods provide little digested energy compared to higher-quality bear foods. Domestic livestock are of greater energetic value, but use of this food by bears often leads to conflicts with humans and subsequent increases in bear mortality. Lake trout, blister rust, and brucellosis diminish grizzly bears foods. Lake trout prey on native cutthroat trout (Oncorhynchus clarkii) in Yellowstone Lake; white pine blister rust has the potential to destroy native whitebark pine (Pinus albicaulis) stands; and management response to bovine brucellosis, a disease found in the Yellowstone bison (Bison bison) and elk (Cervus elaphus), could reduce populations of these 2 species. Exotic species will likely cause more harm than good for Yellowstone grizzly bears. Managers have few options to mitigate or contain the impacts of exotics on Yellowstones grizzly bears. Moreover, their potential negative impacts have only begun to unfold. Exotic species may lead to the loss of substantial highquality grizzly bear foods, including much of the bison, trout, and pine seeds that Yellowstone grizzly bears currently depend upon.

  15. Grizzly bear habitat selection is scale dependent.

    Science.gov (United States)

    Ciarniello, Lana M; Boyce, Mark S; Seip, Dale R; Heard, Douglas C

    2007-07-01

    The purpose of our study is to show how ecologists' interpretation of habitat selection by grizzly bears (Ursus arctos) is altered by the scale of observation and also how management questions would be best addressed using predetermined scales of analysis. Using resource selection functions (RSF) we examined how variation in the spatial extent of availability affected our interpretation of habitat selection by grizzly bears inhabiting mountain and plateau landscapes. We estimated separate models for females and males using three spatial extents: within the study area, within the home range, and within predetermined movement buffers. We employed two methods for evaluating the effects of scale on our RSF designs. First, we chose a priori six candidate models, estimated at each scale, and ranked them using Akaike Information Criteria. Using this method, results changed among scales for males but not for females. For female bears, models that included the full suite of covariates predicted habitat use best at each scale. For male bears that resided in the mountains, models based on forest successional stages ranked highest at the study-wide and home range extents, whereas models containing covariates based on terrain features ranked highest at the buffer extent. For male bears on the plateau, each scale estimated a different highest-ranked model. Second, we examined differences among model coefficients across the three scales for one candidate model. We found that both the magnitude and direction of coefficients were dependent upon the scale examined; results varied between landscapes, scales, and sexes. Greenness, reflecting lush green vegetation, was a strong predictor of the presence of female bears in both landscapes and males that resided in the mountains. Male bears on the plateau were the only animals to select areas that exposed them to a high risk of mortality by humans. Our results show that grizzly bear habitat selection is scale dependent. Further, the

  16. Foothills model forest grizzly bear study : project update

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2002-01-01

    This report updates a five year study launched in 1999 to ensure the continued healthy existence of grizzly bears in west-central Alberta by integrating their needs into land management decisions. The objective was to gather better information and to develop computer-based maps and models regarding grizzly bear migration, habitat use and response to human activities. The study area covers 9,700 square km in west-central Alberta where 66 to 147 grizzly bears exist. During the first 3 field seasons, researchers captured and radio collared 60 bears. Researchers at the University of Calgary used remote sensing tools and satellite images to develop grizzly bear habitat maps. Collaborators at the University of Washington used trained dogs to find bear scat which was analyzed for DNA, stress levels and reproductive hormones. Resource Selection Function models are being developed by researchers at the University of Alberta to identify bear locations and to see how habitat is influenced by vegetation cover and oil, gas, forestry and mining activities. The health of the bears is being studied by researchers at the University of Saskatchewan and the Canadian Cooperative Wildlife Health Centre. The study has already advanced the scientific knowledge of grizzly bear behaviour. Preliminary results indicate that grizzlies continue to find mates, reproduce and gain weight and establish dens. These are all good indicators of a healthy population. Most bear deaths have been related to poaching. The study will continue for another two years. 1 fig.

  17. Whitebark pine, grizzly bears, and red squirrels

    Science.gov (United States)

    Mattson, D.J.; Kendall, K.C.; Reinhart, D.P.; Tomback, D.F.; Arno, S.F.; Keane, R.E.

    2001-01-01

    Appropriately enough, much of this book is devoted to discussing management challenges and techniques. However, the impetus for action—the desire to save whitebark pine (Pinus albicaulis)—necessarily arises from the extent to which we cherish it for its beauty and its connections with other things that we value. Whitebark pine is at the hub of a fascinating web of relationships. It is the stuff of great stories (cf. Quammen 1994). One of the more interesting of these stories pertains to the dependence of certain grizzly bear (Ursus arctos horribilis) populations on its seeds, and the role that red squirrels (Tamiasciurus hudsonicus) play as an agent of transfer between tree and bear.

  18. Grizzly bears and mining in the Cheviot region

    Energy Technology Data Exchange (ETDEWEB)

    Symbaluk, M.; Archibald, T. [Foothills Research Inst., Hinton, AB (Canada)

    2008-07-01

    This presentation described a grizzly bear research program conducted by the Foothill Research Institute at the Cheviot mine. The research program uses a satellite land classification protocol and remote sensing tools to map and identify the grizzly bear habitat. Modelling is also conducted to predict bear probabilities. Global information systems (GIS) are used to evaluate bear responses to human activities. Grizzly bear health and wellness is also assessed as part of the programs. Land maps are combined with global positioning systems (GPS) and resource selection function (RSF) models in order to map grizzly bear distribution. Data obtained from the program is used to inform decision-making and support policy development. Previous studies predicted that the grizzly bear population would disappear from the Cheviot mine area after 20 years of its being in operation. The research program provided real data to test predictions made during previous environmental assessments. Grizzly bear populations have actually increased in the mining area. It was concluded that the bears have moved more freely through industrial landscapes than previously predicted. tabs., figs.

  19. How much lox is a grizzly bear worth?

    Science.gov (United States)

    Chase, Jonathan

    2012-01-01

    Using grizzly bears as surrogates for "salmon ecosystem" function, the authors develop a generalizable ecosystem-based management framework that enables decision makers to quantify ecosystem-harvest tradeoffs between wild and human recipients of natural resources like fish.

  20. Trophic cascades from wolves to grizzly bears in Yellowstone.

    Science.gov (United States)

    Ripple, William J; Beschta, Robert L; Fortin, Jennifer K; Robbins, Charles T

    2014-01-01

    We explored multiple linkages among grey wolves (Canis lupus), elk (Cervus elaphus), berry-producing shrubs and grizzly bears (Ursus arctos) in Yellowstone National Park. We hypothesized competition between elk and grizzly bears whereby, in the absence of wolves, increases in elk numbers would increase browsing on berry-producing shrubs and decrease fruit availability to grizzly bears. After wolves were reintroduced and with a reduced elk population, we hypothesized there would be an increase in the establishment of berry-producing shrubs, such as serviceberry (Amelanchier alnifolia), which is a major berry-producing plant. We also hypothesized that the percentage fruit in the grizzly bear diet would be greater after than before wolf reintroduction. We compared the frequency of fruit in grizzly bear scats to elk densities prior to wolf reintroduction during a time of increasing elk densities (1968-1987). For a period after wolf reintroduction, we calculated the percentage fruit in grizzly bear scat by month based on scats collected in 2007-2009 (n = 778 scats) and compared these results to scat data collected before wolf reintroduction. Additionally, we developed an age structure for serviceberry showing the origination year of stems in a northern range study area. We found that over a 19-year period, the percentage frequency of fruit in the grizzly diet (6231 scats) was inversely correlated (P wolves and other large carnivores on elk, a reduced and redistributed elk population, decreased herbivory and increased production of plant-based foods that may aid threatened grizzly bears. © 2013 The Authors. Journal of Animal Ecology © 2013 British Ecological Society.

  1. Grizzly bear nutrition and ecology studies in Yellowstone National Park

    Science.gov (United States)

    Robbins, Charles T.; Schwartz, Charles C.; Gunther, Kerry A.; Servheen, Christopher

    2006-01-01

    T HE CHANCE TO SEE a wild grizzly bear is often the first or second reason people give for visiting Yellow - stone National Park. Public interest in bears is closely coupled with a desire to perpetuate this wild symbol of the American West. Grizzly bears have long been described as a wilderness species requiring large tracts of undisturbed habitat. However, in today’s world, most grizzly bears live in close proximity to humans (Schwartz et al. 2003). Even in Yellowstone National Park, the impacts of humans can affect the long-term survival of bears (Gunther et al. 2002). As a consequence, the park has long supported grizzly bear research in an effort to understand these impacts. Most people are familiar with what happened when the park and the State of Montana closed open-pit garbage dumps in the late 1960s and early 1970s, when at least 229 bears died as a direct result of conflict with humans. However, many may not be as familiar with the ongoing changes in the park’s plant and animal communities that have the potential to further alter the park’s ability to support grizzly bears.

  2. Consumption of pondweed rhizomes by Yellowstone grizzly bears

    Science.gov (United States)

    Mattson, D.J.; Podruzny, S.R.; Haroldson, M.A.

    2005-01-01

    Pondweeds (Potamogeton spp.) are common foods of waterfowl throughout the Northern Hemisphere. However, consumption of pondweeds by bears has been noted only once, in Russia. We documented consumption of pondweed rhizomes by grizzly bears (Ursus arctos) in the Yellowstone region, 1977-96, during investigations of telemetry locations obtained from 175 radiomarked bears. We documented pondweed excavations at 25 sites and detected pondweed rhizomes in 18 feces. We observed grizzly bears excavating and consuming pondweed on 2 occasions. All excavations occurred in wetlands that were inundated during and after snowmelt, but dry by late August or early September of most years. These wetlands were typified by the presence of inflated sedge (Carex vesicaria) and occurred almost exclusively on plateaus of Pliocene-Pleistocene detrital sediments or volcanic rhyolite flows. Bears excavated wetlands with pondweeds when they were free of standing water, most commonly during October and occasionally during spring prior to the onset of terminal snowmelt. Most excavations were about 4.5 cm deep, 40 cubic decimeter (dm3) in total volume, and targeted the thickened pondweed rhizomes. Starch content of rhizomes collected near grizzly bear excavations averaged 28% (12% SD; n = 6). These results add to the documented diversity of grizzly bear food habits and, because pondweed is distributed circumboreally, also raise the possibility that consumption of pondweed by grizzly bears has been overlooked in other regions.

  3. Density dependence, whitebark pine, and vital rates of grizzly bears

    Science.gov (United States)

    van Manen, Frank T.; Haroldson, Mark A.; Bjornlie, Daniel D; Ebinger, Michael R.; Thompson, Daniel J.; Costello, Cecily M; White, Gary C.

    2016-01-01

    Understanding factors influencing changes in population trajectory is important for effective wildlife management, particularly for populations of conservation concern. Annual population growth of the grizzly bear (Ursus arctos) population in the Greater Yellowstone Ecosystem, USA has slowed from 4.2–7.6% during 1983–2001 to 0.3–2.2% during 2002–2011. Substantial changes in availability of a key food source and bear population density have occurred. Whitebark pine (Pinus albicaulis), the seeds of which are a valuable but variable fall food for grizzly bears, has experienced substantial mortality primarily due to a mountain pine beetle (Dendroctonus ponderosae) outbreak that started in the early 2000s. Positive growth rates of grizzly bears have resulted in populations reaching high densities in some areas and have contributed to continued range expansion. We tested research hypotheses to examine if changes in vital rates detected during the past decade were more associated with whitebark pine decline or, alternatively, increasing grizzly bear density. We focused our assessment on known-fate data to estimate survival of cubs-of-the-year (cubs), yearlings, and independent bears (≥2 yrs), and reproductive transition of females from having no offspring to having cubs. We used spatially and temporally explicit indices for grizzly bear density and whitebark pine mortality as individual covariates. Models indicated moderate support for an increase in survival of independent male bears over 1983–2012, whereas independent female survival did not change. Cub survival, yearling survival, and reproductive transition from no offspring to cubs all changed during the 30-year study period, with lower rates evident during the last 10–15 years. Cub survival and reproductive transition were negatively associated with an index of grizzly bear density, indicating greater declines where bear densities were higher. Our analyses did not support a similar relationship for the

  4. Grizzly bear corticosteroid binding globulin: Cloning and serum protein expression.

    Science.gov (United States)

    Chow, Brian A; Hamilton, Jason; Alsop, Derek; Cattet, Marc R L; Stenhouse, Gordon; Vijayan, Mathilakath M

    2010-06-01

    Serum corticosteroid levels are routinely measured as markers of stress in wild animals. However, corticosteroid levels rise rapidly in response to the acute stress of capture and restraint for sampling, limiting its use as an indicator of chronic stress. We hypothesized that serum corticosteroid binding globulin (CBG), the primary transport protein for corticosteroids in circulation, may be a better marker of the stress status prior to capture in grizzly bears (Ursus arctos). To test this, a full-length CBG cDNA was cloned and sequenced from grizzly bear testis and polyclonal antibodies were generated for detection of this protein in bear sera. The deduced nucleotide and protein sequences were 1218 bp and 405 amino acids, respectively. Multiple sequence alignments showed that grizzly bear CBG (gbCBG) was 90% and 83% identical to the dog CBG nucleotide and amino acid sequences, respectively. The affinity purified rabbit gbCBG antiserum detected grizzly bear but not human CBG. There were no sex differences in serum total cortisol concentration, while CBG expression was significantly higher in adult females compared to males. Serum cortisol levels were significantly higher in bears captured by leg-hold snare compared to those captured by remote drug delivery from helicopter. However, serum CBG expression between these two groups did not differ significantly. Overall, serum CBG levels may be a better marker of chronic stress, especially because this protein is not modulated by the stress of capture and restraint in grizzly bears.

  5. Cannibalism and predation on black bears by grizzly bears in the Yellowstone ecosystem, 1975-1990

    Science.gov (United States)

    Mattson, D.J.; Knight, R.R.; Blanchard, B.M.

    1992-01-01

    We documented one instance of an adult male grizzly bear preying upon a black bear and four instances where circumstantial evidence suggested that grizzly bears (two cubs-of-the-year, one yearling female that was injured, and one adult male) had been preyed upon by conspecifics. We also examined feces of grizzly bears for bear remains. Remains of bears tended to be more common in spring feces and did not differ in frequency between early and late years of the study. Our observations generally support existing hypotheses concerning cannibalism among bears.

  6. Chromatographic (TLC) differentiation of grizzly bear and black bear scats

    Science.gov (United States)

    Picton, Harold D.; Kendall, Katherine C.

    1994-01-01

    While past work concluded that thin-layer chromatography (TLC) was inadequate for the separation of grizzly (Ursus arctos horribilis) and black bear (U. americanus) scats, our study found differences adequate for species separation. A key was constructed using 19 of 40 data points recorded on each(N)=356 profiles of 178) know-species scat. Accuracy was best for late summer scats (94%). Methods for specimen preparation, analysis, and reading the TLC profiles are discussed. Factors involved in scat variation were tested.

  7. Habitat use and behavior of grizzly bears in the Arctic National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report covers habitat use and behavior of grizzly bears in the Arctic National Wildlife Refuge. Habitat use and behavior of grizzly bears (Ursus arctos) wer2...

  8. Disseminated pleomorphic myofibrosarcoma in a grizzly bear (Ursus arctos horribilis).

    Science.gov (United States)

    Mete, A; Woods, L; Famini, D; Anderson, M

    2012-01-01

    The pathological and diagnostic features of a widely disseminated pleomorphic high-grade myofibroblastic sarcoma are described in a 23-year-old male brown bear (Ursus arctos horribilis). Firm, solid, white to tan neoplastic nodules, often with cavitated or soft grey-red necrotic centres, were observed throughout most internal organs, subcutaneous tissues and skeletal muscles on gross examination. Microscopically, the tumour consisted of pleomorphic spindle cells forming interlacing fascicles with a focal storiform pattern with large numbers of bizarre polygonal multinucleate cells, frequently within a collagenous stroma. Immunohistochemistry, Masson's trichrome stain and transmission electron microscopy designated the myofibroblast as the cell of origin. This is the first case of a high-grade myofibrosarcoma in a grizzly bear.

  9. Parasites in grizzly bears from the central Canadian Arctic.

    Science.gov (United States)

    Gau, R J; Kutz, S; Elkin, B T

    1999-07-01

    Standardized flotation techniques were used to survey 56 grizzly bear (Ursus arctos) fecal samples for parasites. The samples were collected during the spring and autumn of 1995 and 1996 in the central Arctic of the Northwest Territories (Canada). Parasites of the genera Nematodirus, gastrointestinal coccidia, and an unidentified first stage protostrongylid larva are reported for the first time from grizzly bear feces in North America. Parasites of the genera Diphyllobothrium and Baylisascaris also were collected. Prevalence of gastrointestinal parasites were significantly different between the spring and autumn seasons (31% and 58% respectively). Thus, we provide evidence supporting the theory that bears void gastrointestinal parasites before hibernation.

  10. Grizzly bear density in Glacier National Park, Montana

    Science.gov (United States)

    Kendall, K.C.; Stetz, J.B.; Roon, David A.; Waits, L.P.; Boulanger, J.B.; Paetkau, David

    2008-01-01

    We present the first rigorous estimate of grizzly bear (Ursus arctos) population density and distribution in and around Glacier National Park (GNP), Montana, USA. We used genetic analysis to identify individual bears from hair samples collected via 2 concurrent sampling methods: 1) systematically distributed, baited, barbed-wire hair traps and 2) unbaited bear rub trees found along trails. We used Huggins closed mixture models in Program MARK to estimate total population size and developed a method to account for heterogeneity caused by unequal access to rub trees. We corrected our estimate for lack of geographic closure using a new method that utilizes information from radiocollared bears and the distribution of bears captured with DNA sampling. Adjusted for closure, the average number of grizzly bears in our study area was 240.7 (95% CI = 202–303) in 1998 and 240.6 (95% CI = 205–304) in 2000. Average grizzly bear density was 30 bears/1,000 km2, with 2.4 times more bears detected per hair trap inside than outside GNP. We provide baseline information important for managing one of the few remaining populations of grizzlies in the contiguous United States.

  11. 78 FR 29774 - Endangered and Threatened Wildlife and Plants; Draft Revised Supplement to the Grizzly Bear...

    Science.gov (United States)

    2013-05-21

    ... the Grizzly Bear Recovery Plan; Extension of Public Comment Period AGENCY: Fish and Wildlife Service... Grizzly Bear Recovery Plan in the greater Yellowstone area. If you have previously submitted comments... Revised Supplement to the Grizzly Bear Recovery Plan is available at...

  12. 78 FR 17708 - Endangered and Threatened Wildlife and Plants; Draft Revised Supplement to the Grizzly Bear...

    Science.gov (United States)

    2013-03-22

    ... the Grizzly Bear Recovery Plan AGENCY: Fish and Wildlife Service, Interior. ACTION: Notice of document... availability of a draft Revised Supplement to the Grizzly Bear Recovery Plan. Specifically, this supplement..., Grizzly bears (Ursus arctos horribilis) are federally listed as threatened under the Endangered...

  13. Predicting grizzly bear density in western North America.

    Directory of Open Access Journals (Sweden)

    Garth Mowat

    Full Text Available Conservation of grizzly bears (Ursus arctos is often controversial and the disagreement often is focused on the estimates of density used to calculate allowable kill. Many recent estimates of grizzly bear density are now available but field-based estimates will never be available for more than a small portion of hunted populations. Current methods of predicting density in areas of management interest are subjective and untested. Objective methods have been proposed, but these statistical models are so dependent on results from individual study areas that the models do not generalize well. We built regression models to relate grizzly bear density to ultimate measures of ecosystem productivity and mortality for interior and coastal ecosystems in North America. We used 90 measures of grizzly bear density in interior ecosystems, of which 14 were currently known to be unoccupied by grizzly bears. In coastal areas, we used 17 measures of density including 2 unoccupied areas. Our best model for coastal areas included a negative relationship with tree cover and positive relationships with the proportion of salmon in the diet and topographic ruggedness, which was correlated with precipitation. Our best interior model included 3 variables that indexed terrestrial productivity, 1 describing vegetation cover, 2 indices of human use of the landscape and, an index of topographic ruggedness. We used our models to predict current population sizes across Canada and present these as alternatives to current population estimates. Our models predict fewer grizzly bears in British Columbia but more bears in Canada than in the latest status review. These predictions can be used to assess population status, set limits for total human-caused mortality, and for conservation planning, but because our predictions are static, they cannot be used to assess population trend.

  14. Predicting grizzly bear density in western North America.

    Science.gov (United States)

    Mowat, Garth; Heard, Douglas C; Schwarz, Carl J

    2013-01-01

    Conservation of grizzly bears (Ursus arctos) is often controversial and the disagreement often is focused on the estimates of density used to calculate allowable kill. Many recent estimates of grizzly bear density are now available but field-based estimates will never be available for more than a small portion of hunted populations. Current methods of predicting density in areas of management interest are subjective and untested. Objective methods have been proposed, but these statistical models are so dependent on results from individual study areas that the models do not generalize well. We built regression models to relate grizzly bear density to ultimate measures of ecosystem productivity and mortality for interior and coastal ecosystems in North America. We used 90 measures of grizzly bear density in interior ecosystems, of which 14 were currently known to be unoccupied by grizzly bears. In coastal areas, we used 17 measures of density including 2 unoccupied areas. Our best model for coastal areas included a negative relationship with tree cover and positive relationships with the proportion of salmon in the diet and topographic ruggedness, which was correlated with precipitation. Our best interior model included 3 variables that indexed terrestrial productivity, 1 describing vegetation cover, 2 indices of human use of the landscape and, an index of topographic ruggedness. We used our models to predict current population sizes across Canada and present these as alternatives to current population estimates. Our models predict fewer grizzly bears in British Columbia but more bears in Canada than in the latest status review. These predictions can be used to assess population status, set limits for total human-caused mortality, and for conservation planning, but because our predictions are static, they cannot be used to assess population trend.

  15. Potential energetic effects of mountain climbers on foraging grizzly bears

    Science.gov (United States)

    White, D.; Kendall, K.C.; Picton, H.D.

    1999-01-01

    Most studies of the effects of human disturbance on grizzly bears (Ursus arctos horribilis) have not quantified the energetic effects of such interactions. In this study, we characterized activity budgets of adult grizzly bears as they foraged on aggregations of adult army cutworm moths (Euxoa auxiliaris) in the alpine of Glacier National Park, Montana, during 1992, 1994, and 1995. We compared the activity budgets of climber-disturbed bears to those of undisturbed bears to estimate the energetic impact of climber disturbance. When bears detected climbers, they subsequently spent 53% less time foraging on moths, 52% more time moving within the foraging area, and 23% more time behaving aggressively, compared to when they were not disturbed. We estimated that grizzly bears could consume approximately 40,000 moths/day or 1,700 moths/hour. At 0.44 kcal/moth, disruption of moth feeding cost bears approximately 12 kcal/minute in addition to the energy expended in evasive maneuvers and defensive behaviors. To reduce both climber interruption of bear foraging and the potential for aggressive bear-human encounters, we recommend routing climbers around moth sites used by bears or limiting access to these sites during bear-use periods.

  16. Coefficients of Productivity for Yellowstone's Grizzly Bear Habitat

    Science.gov (United States)

    Mattson, David John; Barber, Kim; Maw, Ralene; Renkin, Roy

    2004-01-01

    This report describes methods for calculating coefficients used to depict habitat productivity for grizzly bears in the Yellowstone ecosystem. Calculations based on these coefficients are used in the Yellowstone Grizzly Bear Cumulative Effects Model to map the distribution of habitat productivity and account for the impacts of human facilities. The coefficients of habitat productivity incorporate detailed information that was collected over a 20-year period (1977-96) on the foraging behavior of Yellowstone's bears and include records of what bears were feeding on, when and where they fed, the extent of that feeding activity, and relative measures of the quantity consumed. The coefficients also incorporate information, collected primarily from 1986 to 1992, on the nutrient content of foods that were consumed, their digestibility, characteristic bite sizes, and the energy required to extract and handle each food. Coefficients were calculated for different time periods and different habitat types, specific to different parts of the Yellowstone ecosystem. Stratifications included four seasons of bear activity (spring, estrus, early hyperphagia, late hyperphagia), years when ungulate carrion and whitebark pine seed crops were abundant versus not, areas adjacent to (bear activity in each region, habitat type, and time period were incorporated into calculations, controlling for the effects of proximity to human facilities. The coefficients described in this report and associated estimates of grizzly bear habitat productivity are unique among many efforts to model the conditions of bear habitat because calculations include information on energetics derived from the observed behavior of radio-marked bears.

  17. How much lox is a grizzly bear worth?

    Directory of Open Access Journals (Sweden)

    Jonathan Chase

    Full Text Available Using grizzly bears as surrogates for "salmon ecosystem" function, the authors develop a generalizable ecosystem-based management framework that enables decision makers to quantify ecosystem-harvest tradeoffs between wild and human recipients of natural resources like fish.

  18. Science and management of Rocky Mountain grizzly bears

    Science.gov (United States)

    Mattson, D.J.; Herrero, S.; Wright, R.G.; Pease, C.M.

    1996-01-01

    The science and management of grizzly bears (Ursus arctos horribilis) in the Rocky Mountains of North America have spawned considerable conflict and controversy. Much of this can be attributed to divergent public values, but the narrow perceptions and incomplete and fragmented problem definitions of those involved have exacerbated an inherently difficult situation. We present a conceptual model that extends the traditional description of the grizzly bear conservation system to include facets of the human domain such as the behavior of managers, elected officials, and the public. The model focuses on human-caused mortality, the key determinant of grizzly bear population growth in this region and the interactions and feedback loops among humans that have a major potential influence on bear mortality. We also briefly evaluate existing information and technical methods relevant to understanding this complex human-biophysical system. We observe not only that the extant knowledge is insufficient for prediction (and in some cases for description), but also that traditional positivistic science alone is not adequate for dealing with the problems of grizzly bear conservation. We recommend changes in science and management that could improve learning and responsiveness among the involved individuals and organizations, clarify some existing uncertainty, and thereby increase the effectiveness of grizzly bear conservation and management. Although adaptive management is a promising approach, we point out some keya??as yet unfulfilleda??contingencies for implementation of a method such as this one that relies upon social processes and structures that promote open learning and flexibility in all facets of the policy process.

  19. Response of Yellowstone grizzly bears to changes in food resources: A synthesis. Final report to the Interagency Grizzly Bear Committee and Yellowstone Ecosystem Subcommittee

    Science.gov (United States)

    ,; van Manen, Frank T.; Cecily M, Costello; Haroldson, Mark A.; Daniel D, Bjornlie; Michael R, Ebinger; Kerry A, Gunther; Mary Frances, Mahalovich; Daniel J, Thompson; Megan D, Higgs; Irvine, Kathryn M.; Kristin, Legg; Daniel, Tyers; Landenburger, Lisa; Steven L, Cain; Frey, Kevin L.; Aber, Bryan C.; Schwartz, Charles C.

    2013-01-01

    The Yellowstone grizzly bear (Ursus arctos) was listed as a threatened species in 1975 (Federal Register 40 FR:31734-31736). Since listing, recovery efforts have focused on increasing population size, improving habitat security, managing bear mortalities, and reducing bear-human conflicts. The Interagency Grizzly Bear Committee (IGBC; partnership of federal and state agencies responsible for grizzly bear recovery in the lower 48 states) and its Yellowstone Ecosystem Subcommitte (YES; federal, state, county, and tribal partners charged with recovery of grizzly bears in the Greater Yelowston Ecosystem [GYE]) tasked the Interagency Grizzly Bear Study Team to provide information and further research relevant to three concerns arising from the 9th Circuit Court of Appeals November 2011 decision: 1) the ability of grizzly bears as omnivores to find alternative foods to whitebark pine seeds; 2) literature to support their conclusions; and 3) the non-intuitive biological reality that impacts can occur to individuals without causing the overall population to decline. Specifically, the IGBC and YES requested a comprehensive synthesis of the current state of knowledge regarding whitebark pinbe decline and individual and population-level responses of grizzly bears to changing food resources in the GYE. This research was particularly relevant to grizzly bear conservation given changes in the population trajectory observed during the last decade.

  20. Acquired arteriovenous fistula in a grizzly bear (Ursus arctos horribilis).

    Science.gov (United States)

    Tuttle, Allison D; MacLean, Robert A; Linder, Keith; Cullen, John M; Wolfe, Barbara A; Loomis, Michael

    2009-03-01

    A captive adult male grizzly bear (Ursus arctos horribilis) was evaluated due to multifocal wounds of the skin and subcutaneous tissues sustained as a result of trauma from another grizzly bear. On presentation, one lesion that was located in the perineal region seemed to be a deep puncture with purple tissue protruding from it. This perineal wound did not heal in the same manner or rate as did the other wounds. Twenty-five days after initial detection, substantial active hemorrhage from the lesion occurred and necessitated anesthesia for examination of the bear. The entire lesion was surgically excised, which later proved curative. An acquired arteriovenous fistula was diagnosed via histopathology. Arteriovenous fistulas can develop after traumatic injury and should be considered as a potential complication in bears with nonhealing wounds.

  1. MEDULLOBLASTOMA IN A GRIZZLY BEAR (URSUS ARCTOS HORRIBLIS).

    Science.gov (United States)

    Mitchell, Jeffrey W; Thomovsky, Stephanie A; Chen, Annie V; Layton, Arthur W; Haldorson, Gary; Tucker, Russell L; Roberts, Gregory

    2015-09-01

    A 3-yr-old female spayed grizzly bear (Ursus arctos horribilis) was evaluated for seizure activity along with lethargy, inappetence, dull mentation, and aggressive behavior. Magnetic resonance (MR) examination of the brain revealed a contrast-enhanced right cerebellar mass with multifocal smaller nodules located in the left cerebellum, thalamus, hippocampus, and cerebrum with resultant obstructive hydrocephalus. Cerebrospinal fluid analysis revealed mild mononuclear pleocytosis, with differentials including inflammatory versus neoplastic processes. Blood and cerebrospinal fluid were also submitted for polymerase chain reaction and agar gel immunodiffusion to rule out infectious causes of meningitis/encephalitis. While awaiting these results, the bear was placed on steroid and antibiotic therapy. Over the next week, the bear deteriorated; she died 1 wk after MR. A complete postmortem examination, including immunohistochemisty, revealed the cerebellar mass to be a medulloblastoma. This is the only case report, to the authors' knowledge, describing a medulloblastoma in a grizzly bear.

  2. Trend of the Yellowstone Grizzly Bear Population

    Directory of Open Access Journals (Sweden)

    L. L. Eberhardt

    2010-01-01

    Full Text Available Yellowstone's grizzlies (Ursus arctos have been studied for more than 40 years. Radiotelemetry has been used to obtain estimates of the rate of increase of the population, with results reported by Schwartz et al. (2006. Counts of females with cubs-of-the-year “unduplicated” also provide an index of abundance and are the primary subject of this report. An exponential model was fitted to n=24 such counts, using nonlinear leastsquares. Estimates of the rate of increase, r, were about 0.053. 95% confidence intervals, were obtained by several different methods, and all had lower limits substantially above zero, indicating that the population has been increasing steadily, in contrast to the results of Schwartz et al. (2006, which could not exclude a decreasing population. The grizzly data have been repeatedly mis-used in current literature for reasons explained here.

  3. Contrasting activity patterns of sympatric and allopatric black and grizzly bears

    Science.gov (United States)

    Schwartz, C.C.; Cain, S.L.; Podruzny, S.; Cherry, S.; Frattaroli, L.

    2010-01-01

    The distribution of grizzly (Ursus arctos) and American black bears (U. americanus) overlaps in western North America. Few studies have detailed activity patterns where the species are sympatric and no studies contrasted patterns where populations are both sympatric and allopatric. We contrasted activity patterns for sympatric black and grizzly bears and for black bears allopatric to grizzly bears, how human influences altered patterns, and rates of grizzlyblack bear predation. Activity patterns differed between black bear populations, with those sympatric to grizzly bears more day-active. Activity patterns of black bears allopatric with grizzly bears were similar to those of female grizzly bears; both were crepuscular and day-active. Male grizzly bears were crepuscular and night-active. Both species were more night-active and less day-active when ???1 km from roads or developments. In our sympatric study area, 2 of 4 black bear mortalities were due to grizzly bear predation. Our results suggested patterns of activity that allowed for intra- and inter-species avoidance. National park management often results in convergence of locally high human densities in quality bear habitat. Our data provide additional understanding into how bears alter their activity patterns in response to other bears and humans and should help park managers minimize undesirable bearhuman encounters when considering needs for temporal and spatial management of humans and human developments in bear habitats. ?? 2010 The Wildlife Society.

  4. Microsatellite analysis of paternity and reproduction in Arctic grizzly bears.

    Science.gov (United States)

    Craighead, L; Paetkau, D; Reynolds, H V; Vyse, E R; Strobeck, C

    1995-01-01

    We report data from analyses of microsatellite loci of 30 grizzly bear family groups which demonstrate that each cub in a litter can be sired independently, and we derive estimates of maximum reproductive success for males, from an Arctic population in northwestern Alaska that is minimally affected by human activities. These analyses were made possible by the use of single-locus primers that amplified both of an individual's alleles at eight microsatellite loci and by detailed knowledge of maternal/offspring relationships that allowed the identification of paternal alleles. No single male was responsible for more than approximately 11% of known offspring, and no more than 49% of breeding-age males successfully bred. These data contribute to an understanding of the genetic and demographic basis of male reproductive success, which is of vital importance in the maintenance of small, isolated grizzly bear populations.

  5. Oil and gas planning and development in Alberta : new approaches to integrate grizzly bear conservation

    Energy Technology Data Exchange (ETDEWEB)

    Stenhouse, G. [Foothills Model Forest Grizzly Bear Research Program, AB (Canada)

    2007-07-01

    This paper reported on a grizzly bear research program that was initiated in the province of Alberta to provide new knowledge and tools to ensure the long term survival of grizzly bears on a multiple use landscape. The Foothills Model Forest (FMF) Grizzly Bear Research Program was formed by scientists from across Canada from a variety of scientific disciplines. A strong partner base has been created to allow the FMF's research efforts to span the entire current distribution of grizzly bear habitat in Alberta. The FMF has provided new large scale seamless maps of grizzly bear habitat and, using detailed grizzly bear GPS movement data, has constructed and tested models that can identify key grizzly bear habitat. This presentation focused on the results of 9 years of applied research and described the new tools and models that are now available to program partners in Alberta. The products are currently being used by both industry and government in Alberta as new standards in landscape management planning in grizzly bear habitat. The author suggested that the approach taken with grizzly bears in Alberta could be used and adapted for a variety of wildlife species in the north. figs.

  6. New challenges for grizzly bear management in Yellowstone National Park

    Science.gov (United States)

    van Manen, Frank T.; Gunther, Kerry A.

    2016-01-01

    A key factor contributing to the success of grizzly bear Ursus arctos conservation in the Greater Yellowstone Ecosystem has been the existence of a large protected area, Yellowstone National Park. We provide an overview of recovery efforts, how demographic parameters changed as the population increased, and how the bear management program in Yellowstone National Park has evolved to address new management challenges over time. Finally, using the management experiences in Yellowstone National Park, we present comparisons and perspectives regarding brown bear management in Shiretoko National Park.

  7. Energy homeostasis regulatory peptides in hibernating grizzly bears.

    Science.gov (United States)

    Gardi, János; Nelson, O Lynne; Robbins, Charles T; Szentirmai, Eva; Kapás, Levente; Krueger, James M

    2011-05-15

    Grizzly bears (Ursus arctos horribilis) are inactive for up to 6 months during hibernation. They undergo profound seasonal changes in food intake, body mass, and energy expenditure. The circa-annual regulation of metabolism is poorly understood. In this study, we measured plasma ghrelin, leptin, obestatin, and neuropeptide-Y (NPY) levels, hormones known to be involved in the regulation of energy homeostasis, in ten grizzly bears. Blood samples were collected during the active summer period, early hibernation and late hibernation. Plasma levels of leptin, obestatin, and NPY did not change between the active and the hibernation periods. Plasma total ghrelin and desacyl-ghrelin concentrations significantly decreased during the inactive winter period compared to summer levels. The elevated ghrelin levels may help enhance body mass during pre-hibernation, while the low plasma ghrelin concentrations during hibernation season may contribute to the maintenance of hypophagia, low energy utilization and behavioral inactivity. Our results suggest that ghrelin plays a potential role in the regulation of metabolic changes and energy homeostasis during hibernation in grizzly bears.

  8. Salmon-Eating Grizzly Bears Exposed to Elevated Levels of Marine Derived Persistent Organic Pollutants

    Science.gov (United States)

    Christensen, J. R.; Ross, P. S.; Whiticar, M. J.

    2004-12-01

    The coastal grizzly bears of British Columbia (BC, Canada) rely heavily on salmon returning from the Pacific Ocean, whereas interior bears do not have access to or readily utilize this marine-derived food source. Since salmon have been shown to accumulate persistent organic pollutants (POPs) from the North Pacific Ocean, we hypothesized that salmon consumption by grizzly bears would be reflected by an increase in the POP burden. To test this hypothesis we collected hair and fat tissue from grizzlies at various locations around BC to compare salmon-eating (coastal) grizzlies to non-salmon-eating (interior) grizzlies. We characterized the feeding habits for each bear sampled by measuring the stable carbon and nitrogen isotope signature of their hair. The positive relationship between 13C/12C and 15N/14N isotopic ratios suggests that the majority of the meat portion of the diet of coastal grizzlies is coming from salmon, rather than from terrestrial or freshwater sources. By contrast, stable isotope ratios revealed that interior bears have an almost exclusive vegetarian diet with no marine influence. As hypothesized, the coastal grizzly bears have significantly greater OC pesticide and lower-brominated PBDE congener body burden than the interior grizzlies. We also found a positive relationship between C and N isotope ratios and these same POP contaminants in bear tissue. Overall, these results demonstrate that Pacific salmon represents a significant vector delivering both OC pesticides and PBDEs to BC coastal grizzly bears.

  9. Exploitation of pocket gophers and their food caches by grizzly bears

    Science.gov (United States)

    Mattson, D.J.

    2004-01-01

    I investigated the exploitation of pocket gophers (Thomomys talpoides) by grizzly bears (Ursus arctos horribilis) in the Yellowstone region of the United States with the use of data collected during a study of radiomarked bears in 1977-1992. My analysis focused on the importance of pocket gophers as a source of energy and nutrients, effects of weather and site features, and importance of pocket gophers to grizzly bears in the western contiguous United States prior to historical extirpations. Pocket gophers and their food caches were infrequent in grizzly bear feces, although foraging for pocket gophers accounted for about 20-25% of all grizzly bear feeding activity during April and May. Compared with roots individually excavated by bears, pocket gopher food caches were less digestible but more easily dug out. Exploitation of gopher food caches by grizzly bears was highly sensitive to site and weather conditions and peaked during and shortly after snowmelt. This peak coincided with maximum success by bears in finding pocket gopher food caches. Exploitation was most frequent and extensive on gently sloping nonforested sites with abundant spring beauty (Claytonia lanceolata) and yampah (Perdieridia gairdneri). Pocket gophers are rare in forests, and spring beauty and yampah roots are known to be important foods of both grizzly bears and burrowing rodents. Although grizzly bears commonly exploit pocket gophers only in the Yellowstone region, this behavior was probably widespread in mountainous areas of the western contiguous United States prior to extirpations of grizzly bears within the last 150 years.

  10. Serologic survey for Trichinella spp. in grizzly bears from Alaska.

    Science.gov (United States)

    Zarnke, R L; Gamble, R; Heckert, R A; Ver Hoef, J

    1997-07-01

    Blood was collected from 878 grizzly bears (Ursus arctos) in seven geographic areas of Alaska from 1973 to 1987. An enzyme-linked immunosorbent assay procedure was used to test sera for evidence of exposure to Trichinella spp. Serum antibody prevalence ranged from 5% (10 positive of 196 tested) in the Southern Region of the state to 83% (355 of 430 tested) in the Northern Region. These major discrepancies may be a result of differing food habits of bears in the major geographic areas. Prevalence was higher in older age cohorts. Neither year-of-collection nor sex had a significant effect on prevalence.

  11. Use of naturally occurring mercury to determine the importance of cutthroat trout to Yellowstone grizzly bears

    Science.gov (United States)

    Felicetti, L.A.; Schwartz, C.C.; Rye, R.O.; Gunther, K.A.; Crock, J.G.; Haroldson, M.A.; Waits, L.; Robbins, C.T.

    2004-01-01

    Spawning cutthroat trout (Oncorhynchus clarki (Richardson, 1836)) are a potentially important food resource for grizzly bears (Ursus arctos horribilis Ord, 1815) in the Greater Yellowstone Ecosystem. We developed a method to estimate the amount of cutthroat trout ingested by grizzly bears living in the Yellowstone Lake area. The method utilized (i) the relatively high, naturally occurring concentration of mercury in Yellowstone Lake cutthroat trout (508 ± 93 ppb) and its virtual absence in all other bear foods (6 ppb), (ii) hair snares to remotely collect hair from bears visiting spawning cutthroat trout streams between 1997 and 2000, (iii) DNA analyses to identify the individual and sex of grizzly bears leaving a hair sample, (iv) feeding trials with captive bears to develop relationships between fish and mercury intake and hair mercury concentrations, and (v) mercury analyses of hair collected from wild bears to estimate the amount of trout consumed by each bear. Male grizzly bears consumed an average of 5 times more trout/kg bear than did female grizzly bears. Estimated cutthroat trout intake per year by the grizzly bear population was only a small fraction of that estimated by previous investigators, and males consumed 92% of all trout ingested by grizzly bears.

  12. Serologic survey of Toxoplasma gondii in grizzly bears (Ursus arctos) and black bears (Ursus americanus), from Alaska, 1988 to 1991.

    Science.gov (United States)

    Chomel, B B; Zarnke, R L; Kasten, R W; Kass, P H; Mendes, E

    1995-10-01

    We tested 644 serum samples from 480 grizzly bears and 40 black bears from Alaska (USA), collected between 1988 and 1991, for Toxoplasma gondii antibodies, using a commercially available latex agglutination test (LAT). A titer > or = 64 was considered positive. Serum antibody prevalence for T. gondii in grizzly bears (Ursus arctos) was 18% (87 of 480). Prevalence ranged from 9% (seven of 77) on Kodiak Island to 28% (15 of 54) in northern Alaska. Prevalence was directly correlated to age. No grizzly bears grizzly bears captured north of the Arctic Circle. Antibody prevalence in black bears (Ursus americanus) from Interior Alaska was 15% (six of 40), similar to the prevalence in grizzly bears from the same area (13%; five of 40).

  13. Methods to estimate distribution and range extent of grizzly bears in the Greater Yellowstone Ecosystem

    Science.gov (United States)

    Haroldson, Mark A.; Schwartz, Charles C.; , Daniel D. Bjornlie; , Daniel J. Thompson; , Kerry A. Gunther; , Steven L. Cain; , Daniel B. Tyers; Frey, Kevin L.; Aber, Bryan C.

    2014-01-01

    The distribution of the Greater Yellowstone Ecosystem grizzly bear (Ursus arctos) population has expanded into areas unoccupied since the early 20th century. Up-to-date information on the area and extent of this distribution is crucial for federal, state, and tribal wildlife and land managers to make informed decisions regarding grizzly bear management. The most recent estimate of grizzly bear distribution (2004) utilized fixed-kernel density estimators to describe distribution. This method was complex and computationally time consuming and excluded observations of unmarked bears. Our objective was to develop a technique to estimate grizzly bear distribution that would allow for the use of all verified grizzly bear location data, as well as provide the simplicity to be updated more frequently. We placed all verified grizzly bear locations from all sources from 1990 to 2004 and 1990 to 2010 onto a 3-km × 3-km grid and used zonal analysis and ordinary kriging to develop a predicted surface of grizzly bear distribution. We compared the area and extent of the 2004 kriging surface with the previous 2004 effort and evaluated changes in grizzly bear distribution from 2004 to 2010. The 2004 kriging surface was 2.4% smaller than the previous fixed-kernel estimate, but more closely represented the data. Grizzly bear distribution increased 38.3% from 2004 to 2010, with most expansion in the northern and southern regions of the range. This technique can be used to provide a current estimate of grizzly bear distribution for management and conservation applications.

  14. Fire, red squirrels, whitebark pine, and Yellowstone grizzly bears

    Science.gov (United States)

    Podruzny, Shannon; Reinhart, D.P.; Mattson, David J.

    1999-01-01

    Whitebark pine (Pinus albicaulis) habitats are important to Yellowstone grizzly bears (Ursus arctos) as refugia and sources of food. Ecological relationships between whitebark pine, red squirrels (Tamiasciurus hudsonicus), and grizzly bear use of pine seeds on Mt. Washburn in Yellowstone National Park, Wyoming, were examined during 1984-86. Following large-scale fires in 1988, we repeated the study in 1995-97 to examine the effects of fire on availability of whitebark pine seed in red squirrel middens and on bear use of middens. Half of the total length of the original line transects burned. We found no red squirrel middens in burned areas. Post-fire linear-abundance (no./km) of active squirrel middens that were pooled from burned and unburned areas decreased 27% compared to pre-fire abundance, but increased in unburned portions of some habitat types. Mean size of active middens decreased 54% post-fire. Use of pine seeds by bears (linear abundance of excavated middens) in pooled burned and unburned habitats decreased by 64%, likely due to the combined effects of reduced midden availability and smaller midden size. We discourage any further large-scale losses of seed producing trees from management-prescribed fires or timber harvesting until the effects of fire on ecological relationships in the whitebark pine zone are better understood.

  15. Physiologic responses of grizzly bears to different methods of capture.

    Science.gov (United States)

    Cattet, Marc R; Christison, Katina; Caulkett, Nigel A; Stenhouse, Gordon B

    2003-07-01

    The physiologic effects of two methods of capture, chemical immobilization of free-ranging (FR) bears by remote injection from a helicopter and physical restraint (PR) by leg-hold snare prior to chemical immobilization, were compared in 46 grizzly bears (Ursus arctos) handled during 90 captures between 1999 and 2001. Induction dosages and times were greater for FR bears than PR bears, a finding consistent with depletion of, or decreased sensitivity to, catecholamines. Free-ranging bears also had higher rectal temperatures 15 min following immobilization and temperatures throughout handling that correlated positively with induction time. Physically restrained bears had higher white blood cell counts, with more neutrophils and fewer lymphocytes and eosinophils, than did FR bears. This white blood cell profile was consistent with a stress leukogram, possibly affected by elevated levels of serum cortisol. Serum concentrations of alanine aminotransferase, aspartate aminotransferase, and creatine kinase were higher in PR bears that suggested muscle injury. Serum concentrations of sodium and chloride also were higher in PR bears and attributed to reduced body water volume through water deprivation and increased insensible water loss. Overall, different methods of capture resulted in different patterns of physiologic disturbance. Reducing pursuit and drug induction times should help to minimize increase in body temperature and alteration of acid-base balance in bears immobilized by remote injection. Minimizing restraint time and ensuring snare-anchoring cables are short should help to minimize loss of body water and prevent serious muscle injury in bears captured by leg-hold snare.

  16. Trophic cascades from wolves to grizzly bears or changing abundance of bears and alternate foods?

    Science.gov (United States)

    Barber-Meyer, Shannon M.

    2015-01-01

    This is a Forum article commenting on: Ripple, W. J., Beschta, R. L., Fortin, J. K., & Robbins, C. T. (2014) Trophic cascades from wolves to grizzly bears in Yellowstone. Journal of Animal Ecology, 83, 223–233. Comparisons Ripple et al. (2014) used to demonstrate increased fruit availability and consumption by grizzly bears post-wolf reintroduction are flawed and tenuous at best. Importantly, a more parsimonious (than trophic cascades) hypothesis, not sufficiently considered by Ripple et al., exists and is better supported by available data I review.

  17. Trophic cascades from wolves to grizzly bears or changing abundance of bears and alternate foods?

    Science.gov (United States)

    Barber-Meyer, Shannon M

    2015-05-01

    This is a Forum article commenting on: Ripple, W. J., Beschta, R. L., Fortin, J. K., & Robbins, C. T. (2014) Trophic cascades from wolves to grizzly bears in Yellowstone. Journal of Animal Ecology, 83, 223-233. Comparisons Ripple et al. (2014) used to demonstrate increased fruit availability and consumption by grizzly bears post-wolf reintroduction are flawed and tenuous at best. Importantly, a more parsimonious (than trophic cascades) hypothesis, not sufficiently considered by Ripple et al., exists and is better supported by available data I review.

  18. Serologic survey for Toxoplasma gondii in grizzly bears from Alaska.

    Science.gov (United States)

    Zarnke, R L; Dubey, J P; Kwok, O C; Ver Hoef, J M

    1997-04-01

    Blood samples were collected from 892 grizzly bears (Ursus arctos) in Alaska (USA) from 1973 to 1987. Sera were tested for evidence of exposure to Toxoplasma gondii by means of the modified agglutination test. Two hundred twenty sera (25%) had titers > or = 25, the minimum threshold titer. Six hundred seventy-two sera (75%) had titers < 25. Antibody prevalence ranged from 9% (18 positive of 196 tested) in southern areas to 37% (162 of 433 tested) in northern areas. There was no readily apparent explanation for these discrepancies in location-specific prevalence.

  19. Distribution of grizzly bears in the Greater Yellowstone Ecosystem, 2004

    Science.gov (United States)

    Schwartz, C.C.; Haroldson, M.A.; Gunther, K.; Moody, D.

    2006-01-01

    The US Fish and Wildlife Service (USFWS) proposed delisting the Yellowstone grizzly bear (Ursus arctos horribilis) in November 2005. Part of that process required knowledge of the most current distribution of the species. Here, we update an earlier estimate of occupied range (1990–2000) with data through 2004. We used kernel estimators to develop distribution maps of occupied habitats based on initial sightings of unduplicated females (n = 481) with cubs of the year, locations of radiomarked bears (n = 170), and spatially unique locations of conflicts, confrontations, and mortalities (n = 1,075). Although each data set was constrained by potential sampling bias, together they provided insight into areas in the Greater Yellowstone Ecosystem (GYE) currently occupied by grizzly bears. The current distribution of 37,258 km2 (1990–2004) extends beyond the distribution map generated with data from 1990–2000 (34,416 km2 ). Range expansion is particularly evident in parts of the Caribou–Targhee National Forest in Idaho and north of Spanish Peaks on the Gallatin National Forest in Montana.

  20. Body and diet composition of sympatric black and grizzly bears in the Greater Yellowstone Ecosystem

    Science.gov (United States)

    Schwartz, Charles C.; Fortin, Jennifer K.; Teisberg, Justin E.; Haroldson, Mark A.; Servheen, Christopher; Robbins, Charles T.; van Manen, Frank T.

    2013-01-01

    The Greater Yellowstone Ecosystem (GYE) has experienced changes in the distribution and availability of grizzly bear (Ursus arctos) food resources in recent decades. The decline of ungulates, fish, and whitebark pine seeds (Pinus albicaulis) has prompted questions regarding their ability to adapt. We examined body composition and diet of grizzly bears using bioelectrical impedance and stable isotopes to determine if 1) we can detect a change in diet quality associated with the decline in either ungulates or whitebark pine, and 2) the combined decline in ungulates, fish, and pine seeds resulted in a change in grizzly bear carrying capacity in the GYE. We contrasted body fat and mass in grizzly bears with a potential competitor, the American black bear (Ursus americanus), to address these questions. Grizzly bears assimilated more meat into their diet and were in better body condition than black bears throughout the study period, indicating the decline in ungulate resources did not affect grizzly bears more than black bears. We also found no difference in autumn fat levels in grizzly bears in years of good or poor pine seed production, and stable isotope analyses revealed this was primarily a function of switching to meat resources during poor seed-producing years. This dietary plasticity was consistent over the course of our study. We did not detect an overall downward trend in either body mass or the fraction of meat assimilated into the diet by grizzly bears over the past decade, but we did detect a downward trend in percent body fat in adult female grizzly bears after 2006. Whether this decline is an artifact of small sample size or due to the population reaching the ecological carrying capacity of the Yellowstone ecosystem warrants further investigation.

  1. Bacterial populations and metabolites in the feces of free roaming and captive grizzly bears.

    Science.gov (United States)

    Schwab, Clarissa; Cristescu, Bogdan; Boyce, Mark S; Stenhouse, Gordon B; Gänzle, Michael

    2009-12-01

    Gut physiology, host phylogeny, and diet determine the composition of the intestinal microbiota. Grizzly bears (Ursus arctos horribilis) belong to the Order Carnivora, yet feed on an omnivorous diet. The role of intestinal microflora in grizzly bear digestion has not been investigated. Microbiota and microbial activity were analysed from the feces of wild and captive grizzly bears. Bacterial composition was determined using culture-dependent and culture-independent methods. The feces of wild and captive grizzly bears contained log 9.1 +/- 0.5 and log 9.2 +/- 0.3 gene copies x g(-1), respectively. Facultative anaerobes Enterobacteriaceae and enterococci were dominant in wild bear feces. Among the strict anaerobes, the Bacteroides-Prevotella-Porphyromonas group was most prominent. Enterobacteriaceae were predominant in the feces of captive grizzly bears, at log 8.9 +/- 0.5 gene copies x g(-1). Strict anaerobes of the Bacteroides-Prevotella-Porphyromonas group and the Clostridium coccoides cluster were present at log 6.7 +/- 0.9 and log 6.8 +/- 0.8 gene copies x g(-1), respectively. The presence of lactate and short-chain fatty acids (SCFAs) verified microbial activity. Total SCFA content and composition was affected by diet. SCFA composition in the feces of captive grizzly bears resembled the SCFA composition of prey-consuming wild animals. A consistent data set was obtained that associated fecal microbiota and metabolites with the distinctive gut physiology and diet of grizzly bears.

  2. Demography and genetic structure of a recovering grizzly bear population

    Science.gov (United States)

    Kendall, K.C.; Stetz, J.B.; Boulanger, J.; Macleod, A.C.; Paetkau, David; White, Gary C.

    2009-01-01

    Grizzly bears (brown bears; Ursus arctos) are imperiled in the southern extent of their range worldwide. The threatened population in northwestern Montana, USA, has been managed for recovery since 1975; yet, no rigorous data were available to monitor program success. We used data from a large noninvasive genetic sampling effort conducted in 2004 and 33 years of physical captures to assess abundance, distribution, and genetic health of this population. We combined data from our 3 sampling methods (hair trap, bear rub, and physical capture) to construct individual bear encounter histories for use in Huggins-Pledger closed mark-recapture models. Our population estimate, N?? = 765 (95% CI = 715-831) was more than double the existing estimate derived from sightings of females with young. Based on our results, the estimated known, human-caused mortality rate in 2004 was 4.6% (95% CI = 4.2-4.9%), slightly above the 4% considered sustainable; however, the high proportion of female mortalities raises concern. We used location data from telemetry, confirmed sightings, and genetic sampling to estimate occupied habitat. We found that grizzly bears occupied 33,480 km2 in the Northern Continental Divide Ecosystem (NCDE) during 1994-2007, including 10,340 km beyond the Recovery Zone. We used factorial correspondence analysis to identify potential barriers to gene flow within this population. Our results suggested that genetic interchange recently increased in areas with low gene flow in the past; however, we also detected evidence of incipient fragmentation across the major transportation corridor in this ecosystem. Our results suggest that the NCDE population is faring better than previously thought, and they highlight the need for a more rigorous monitoring program.

  3. Grizzly bear hair reveals toxic exposure to mercury through salmon consumption.

    Science.gov (United States)

    Noël, Marie; Spence, Jody; Harris, Kate A; Robbins, Charles T; Fortin, Jennifer K; Ross, Peter S; Christensen, Jennie R

    2014-07-01

    Mercury obtained from the diet accumulates in mammalian hair as it grows thus preserving a record of mercury intake over the growth period of a given hair segment. We adapted a microanalysis approach, using laser ablation inductively coupled plasma mass spectrometry, to characterize temporal changes in mercury exposure and uptake in wild and captive grizzly bears. Captive grizzlies fed diets containing known and varied amounts of mercury provided data to allow prediction of Hg ingestion rates in wild bears. Here, we show, for the first time, that 70% of the coastal grizzly bears sampled had Hg levels exceeding the neurochemical effect level proposed for polar bears. In a context where the international community is taking global actions to reduce Hg emissions through the "Minamata Convention on Mercury", our study provides valuable information on the exposure to mercury of these grizzly bears already under many threats.

  4. Extirpations of grizzly bears in the contiguous United States of America, 1850-2000

    Science.gov (United States)

    Mattson, David J.; Merrill, Troy

    2002-01-01

    We investigated factors associated with the distribution of grizzly bears (Ursus arctos horribilis) in 1850 and their extirpation during 1850–1920 and 1920–1970 in the contiguous United States. We used autologistic regression to describe relations between grizzly bear range in 1850, 1920, and 1970 and potential explanatory factors specified for a comprehensive grid of cells, each 900 km2 in size. We also related persistence, 1920–1970, to range size and shape. Grizzly bear range in 1850 was positively related to occurrence in mountainous ecoregions and the ranges of oaks (Quercus spp.), piñon pines (Pinus edulis and P. monophylla), whitebark pine (P. albicaulis), and bison (Bos bison) and negatively related to occurrence in prairie and hot desert ecoregions. Relations with salmon (Oncorynchus spp.) range and human factors were complex. Persistence of grizzly bear range, 1850–1970, was positively related to occurrence in the Rocky Mountains, whitebark pine range, and local size of grizzly bear range at the beginning of each period, and negatively related to number of humans and the ranges of bison, salmon, and piñon pines. We speculate that foods affected persistence primarily by influencing the frequency of contact between humans and bears. With respect to current conservation, grizzly bears survived from 1920 to 1970 most often where ranges at the beginning of this period were either larger than 20,000 km2 or larger than 7,000 km2 but with a ratio of perimeter to area of grizzly bear range would be as extensive as it is now. Although grizzly bear range in the Yellowstone region is currently the most robust of any to potential future increases in human lethality, bears in this region are threatened by the loss of whitebark pine.

  5. Grizzly Bear Aware: Conflict Resolution and Habitat Restoration in the Centennial Valley and Southwest Montana

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The project will take a three pronged approach to implement conservation actions that prevent or reduce Grizzly Bear human conflicts, enhance habitats and improve...

  6. Prevalence of Trichinella spp. in black bears, grizzly bears, and wolves in the Dehcho Region, Northwest Territories, Canada, including the first report of T. nativa in a grizzly bear from Canada.

    Science.gov (United States)

    Larter, Nicholas C; Forbes, Lorry B; Elkin, Brett T; Allaire, Danny G

    2011-07-01

    Samples of muscle from 120 black bears (Ursus americanus), 11 grizzly bears (Ursus arctos), and 27 wolves (Canis lupus) collected in the Dehcho Region of the Northwest Territories from 2001 to 2010 were examined for the presence of Trichinella spp. larvae using a pepsin-HCl digestion assay. Trichinella spp. larvae were found in eight of 11 (73%) grizzly bears, 14 of 27 (52%) wolves, and seven of 120 (5.8%) black bears. The average age of positive grizzly bears, black bears, and wolves was 13.5, 9.9, and approximately 4 yr, respectively. Larvae from 11 wolves, six black bears, and seven grizzly bears were genotyped. Six wolves were infected with T. nativa and five with Trichinella T6, four black bears were infected with T. nativa and two with Trichinella T6, and all seven grizzly bears were infected with Trichinella T6 and one of them had a coinfection with T. nativa. This is the first report of T. nativa in a grizzly bear from Canada. Bears have been linked to trichinellosis outbreaks in humans in Canada, and black bears are a subsistence food source for residents of the Dehcho region. In order to assess food safety risk it is important to monitor the prevalence of Trichinella spp. in both species of bear and their cohabiting mammalian food sources.

  7. Grizzly bear-human conflicts in the Yellowstone Ecosystem, 1992-2000

    Science.gov (United States)

    Gunther, K.A.; Haroldson, M.A.; Cain, S.L.; Copeland, J.; Frey, K.; Schwartz, C.C.

    2004-01-01

    For many years, the primary strategy for managing grizzly bears (Ursus arctos) that came into conflict with humans in the Greater Yellowstone Ecosystem (GYE) was to capture and translocate the offending bears away from conflict sites. Translocation usually only temporarily alleviated the problems and most often did not result in long-term solutions. Wildlife managers needed to be able to predict the causes, types, locations, and trends of conflicts to more efficiently allocate resources for pro-active rather than reactive management actions. To address this need, we recorded all grizzly bear-human conflicts reported in the GYE during 1992-2000. We analyzed trends in conflicts over time (increasing or decreasing), geographic location on macro- (inside or outside of the designated Yellowstone Grizzly Bear Recovery Zone [YGBRZ]) and micro- (geographic location) scales, land ownership (public or private), and relationship to the seasonal availability of bear foods. We recorded 995 grizzly bear-human conflicts in the GYE. Fifty-three percent of the conflicts occurred outside and 47% inside the YGBRZ boundary. Fifty-nine percent of the conflicts occurred on public and 41% on private land. Incidents of bears damaging property and obtaining anthropogenic foods were inversely correlated to the abundance of naturally occurring bear foods. Livestock depredations occurred independent of the availability of bear foods. To further aid in prioritizing management strategies to reduce conflicts, we also analyzed conflicts in relation to subsequent human-caused grizzly bear mortality. There were 74 human-caused grizzly bear mortalities during the study, primarily from killing bears in defense of life and property (43%) and management removal of bears involved in bear-human conflicts (28%). Other sources of human-caused mortality included illegal kills, electrocution by downed power-lines, mistaken identification by American black bear (Ursus americanus) hunters, and vehicle strikes

  8. Contrafreeloading in grizzly bears: implications for captive foraging enrichment.

    Science.gov (United States)

    McGowan, Ragen T S; Robbins, Charles T; Alldredge, J Richard; Newberry, Ruth C

    2010-01-01

    Although traditional feeding regimens for captive animals were focused on meeting physiological needs to assure good health, more recently emphasis has also been placed on non-nutritive aspects of feeding. The provision of foraging materials to diversify feeding behavior is a common practice in zoos but selective consumption of foraging enrichment items over more balanced "chow" diets could lead to nutrient imbalance. One alternative is to provide balanced diets in a contrafreeloading paradigm. Contrafreeloading occurs when animals choose resources that require effort to exploit when identical resources are freely available. To investigate contrafreeloading and its potential as a theoretical foundation for foraging enrichment, we conducted two experiments with captive grizzly bears (Ursus arctos horribilis). In Experiment 1, bears were presented with five foraging choices simultaneously: apples, apples in ice, salmon, salmon in ice, and plain ice under two levels of food restriction. Two measures of contrafreeloading were considered: weight of earned food consumed and time spent working for earned food. More free than earned food was eaten, with only two bears consuming food extracted from ice, but all bears spent more time manipulating ice containing salmon or apples than plain ice regardless of level of food restriction. In Experiment 2, food-restricted bears were presented with three foraging choices simultaneously: apples, apples inside a box, and an empty box. Although they ate more free than earned food, five bears consumed food from boxes and all spent more time manipulating boxes containing apples than empty boxes. Our findings support the provision of contrafreeloading opportunities as a foraging enrichment strategy for captive wildlife.

  9. The natural food habits of grizzly bears in Yellowstone National Park, 1973-74

    Science.gov (United States)

    Mealey, Stephen Patrick

    1980-01-01

     The natural food habits of grizzly bears (Ursus arctos horribilis Ord) in Yellowstone National Park were investigated in 1973-74 to identify the grizzly's energy sources and trophic level(s), nutrient use, and distribution. Food consumption was determined by scat analysis and field observations. Food quality and digestibility were estimated by chemical analysis. Grizzlies were distributed in 3 distinctive feeding economies: valley/plateau, a grass/rodent economy where grizzlies were intensive diggers; mountain, primarily a grass/springbeauty/root economy where grizzlies were casual diggers; and lake, primarily a fish/grass economy where grizzlies were fishers. The economies occured in areas with fertile soils; distribution of bears within each was related to the occurrence of succulent plants. The feeding cycle in the valley/plateau and mountain economies followed plant phenology. Grizzlies fed primarily on meat before green-up and on succulent herbs afterwards; meat, corms, berries, and nuts became important during the postgrowing season. Succulent grasses and sedges with an importance value percentage of 78.5 were the most important food items consumed. Protein from animal tissue was more digestible than protein from plant tissue. Storage fats were more digestible than structural fats. Food energy and digestibility were directly related. Five principle nutrient materials (listed with their percentage digestibilities) contributed to total energy intake: protein from succulent herbs, 42.8; protein and fat from animal material, 78.1; fat and protein from pine nuts, 73.6; starch, 78.8; and sugar from berries and fruits, digestibility undetermined. Protein from succulent herbs, with a nutritive value percentage of 77.3, was the grizzlies' primary energy source. Because succulent, preflowering herbs had higher protein levels than dry, mature herbs, grizzly use of succulent herbs guaranteed them the highest source of herbaceous protein. Low protein digestibility of

  10. Seasonal habitat use and selection by grizzly bears in Northern British Columbia

    Science.gov (United States)

    Milakovic, B.; Parker, K.L.; Gustine, D.D.; Lay, R.J.; Walker, A.B.D.; Gillingham, M.P.

    2012-01-01

    We defined patterns of habitat use and selection by female grizzly bears (Ursus arctos) in the Besa-Prophet watershed of northern British Columbia. We fitted 13 adult females with Geographic Positioning System (GPS) radio-collars and monitored them between 2001 and 2004. We examined patterns of habitat selection by grizzly bears relative to topographical attributes and 3 potential surrogates of food availability: land-cover class, vegetation biomass or quality (as measured by the Normalized Difference Vegetation Index), and selection value for prey species themselves (moose [Alces alces], elk [Cervus elaphus], woodland caribou [Rangifer tarandus], Stone's sheep [Ovis dalli stonei]). Although vegetation biomass and quality, and selection values for prey were important in seasonal selection by some individual bears, land-cover class, elevation, aspect, and vegetation diversity most influenced patterns of habitat selection across grizzly bears, which rely on availability of plant foods and encounters with ungulate prey. Grizzly bears as a group avoided conifer stands and areas of low vegetation diversity, and selected for burned land-cover classes and high vegetation diversity across seasons. They also selected mid elevations from what was available within seasonal ranges. Quantifying relative use of different attributes helped place selection patterns within the context of the landscape. Grizzly bears used higher elevations (1,595??31 m SE) in spring and lower elevations (1,436??27 m) in fall; the range of average elevations used among individuals was highest (500 m) during the summer. During all seasons, grizzly bears most frequented aspects with high solar gain. Use was distributed across 10 land-cover classes and depended on season. Management and conservation actions must maintain a diverse habitat matrix distributed across a large elevational gradient to ensure persistence of grizzly bears as levels of human access increase in the northern Rocky Mountains

  11. Spatial patterns of breeding success of grizzly bears derived from hierarchical multistate models.

    Science.gov (United States)

    Fisher, Jason T; Wheatley, Matthew; Mackenzie, Darryl

    2014-10-01

    Conservation programs often manage populations indirectly through the landscapes in which they live. Empirically, linking reproductive success with landscape structure and anthropogenic change is a first step in understanding and managing the spatial mechanisms that affect reproduction, but this link is not sufficiently informed by data. Hierarchical multistate occupancy models can forge these links by estimating spatial patterns of reproductive success across landscapes. To illustrate, we surveyed the occurrence of grizzly bears (Ursus arctos) in the Canadian Rocky Mountains Alberta, Canada. We deployed camera traps for 6 weeks at 54 surveys sites in different types of land cover. We used hierarchical multistate occupancy models to estimate probability of detection, grizzly bear occupancy, and probability of reproductive success at each site. Grizzly bear occupancy varied among cover types and was greater in herbaceous alpine ecotones than in low-elevation wetlands or mid-elevation conifer forests. The conditional probability of reproductive success given grizzly bear occupancy was 30% (SE = 0.14). Grizzly bears with cubs had a higher probability of detection than grizzly bears without cubs, but sites were correctly classified as being occupied by breeding females 49% of the time based on raw data and thus would have been underestimated by half. Repeated surveys and multistate modeling reduced the probability of misclassifying sites occupied by breeders as unoccupied to grizzly bear occupancy varied across the landscape. Those patches with highest probabilities of breeding occupancy-herbaceous alpine ecotones-were small and highly dispersed and are projected to shrink as treelines advance due to climate warming. Understanding spatial correlates in breeding distribution is a key requirement for species conservation in the face of climate change and can help identify priorities for landscape management and protection.

  12. Exertional myopathy in a grizzly bear (Ursus arctos) captured by leghold snare.

    Science.gov (United States)

    Cattet, Marc; Stenhouse, Gordon; Bollinger, Trent

    2008-10-01

    We diagnosed exertional myopathy (EM) in a grizzly bear (Ursus arctos) that died approximately 10 days after capture by leghold snare in west-central Alberta, Canada, in June 2003. The diagnosis was based on history, post-capture movement data, gross necropsy, histopathology, and serum enzyme levels. We were unable to determine whether EM was the primary cause of death because autolysis precluded accurate evaluation of all tissues. Nevertheless, comparison of serum aspartate aminotransferase and creatine kinase concentrations and survival between the affected bear and other grizzly bears captured by leghold snare in the same research project suggests EM also occurred in other bears, but that it is not generally a cause of mortality. We propose, however, occurrence of nonfatal EM in grizzly bears after capture by leghold snare has potential implications for use of this capture method, including negative effects on wildlife welfare and research data.

  13. Cardiac function adaptations in hibernating grizzly bears (Ursus arctos horribilis).

    Science.gov (United States)

    Nelson, O Lynne; Robbins, Charles T

    2010-03-01

    Research on the cardiovascular physiology of hibernating mammals may provide insight into evolutionary adaptations; however, anesthesia used to handle wild animals may affect the cardiovascular parameters of interest. To overcome these potential biases, we investigated the functional cardiac phenotype of the hibernating grizzly bear (Ursus arctos horribilis) during the active, transitional and hibernating phases over a 4 year period in conscious rather than anesthetized bears. The bears were captive born and serially studied from the age of 5 months to 4 years. Heart rate was significantly different from active (82.6 +/- 7.7 beats/min) to hibernating states (17.8 +/- 2.8 beats/min). There was no difference from the active to the hibernating state in diastolic and stroke volume parameters or in left atrial area. Left ventricular volume:mass was significantly increased during hibernation indicating decreased ventricular mass. Ejection fraction of the left ventricle was not different between active and hibernating states. In contrast, total left atrial emptying fraction was significantly reduced during hibernation (17.8 +/- 2.8%) as compared to the active state (40.8 +/- 1.9%). Reduced atrial chamber function was also supported by reduced atrial contraction blood flow velocities and atrial contraction ejection fraction during hibernation; 7.1 +/- 2.8% as compared to 20.7 +/- 3% during the active state. Changes in the diastolic cardiac filling cycle, especially atrial chamber contribution to ventricular filling, appear to be the most prominent macroscopic functional change during hibernation. Thus, we propose that these changes in atrial chamber function constitute a major adaptation during hibernation which allows the myocardium to conserve energy, avoid chamber dilation and remain healthy during a period of extremely low heart rates. These findings will aid in rational approaches to identifying underlying molecular mechanisms.

  14. Confronting uncertainty in wildlife management: performance of grizzly bear management.

    Directory of Open Access Journals (Sweden)

    Kyle A Artelle

    Full Text Available Scientific management of wildlife requires confronting the complexities of natural and social systems. Uncertainty poses a central problem. Whereas the importance of considering uncertainty has been widely discussed, studies of the effects of unaddressed uncertainty on real management systems have been rare. We examined the effects of outcome uncertainty and components of biological uncertainty on hunt management performance, illustrated with grizzly bears (Ursus arctos horribilis in British Columbia, Canada. We found that both forms of uncertainty can have serious impacts on management performance. Outcome uncertainty alone--discrepancy between expected and realized mortality levels--led to excess mortality in 19% of cases (population-years examined. Accounting for uncertainty around estimated biological parameters (i.e., biological uncertainty revealed that excess mortality might have occurred in up to 70% of cases. We offer a general method for identifying targets for exploited species that incorporates uncertainty and maintains the probability of exceeding mortality limits below specified thresholds. Setting targets in our focal system using this method at thresholds of 25% and 5% probability of overmortality would require average target mortality reductions of 47% and 81%, respectively. Application of our transparent and generalizable framework to this or other systems could improve management performance in the presence of uncertainty.

  15. Confronting uncertainty in wildlife management: performance of grizzly bear management.

    Science.gov (United States)

    Artelle, Kyle A; Anderson, Sean C; Cooper, Andrew B; Paquet, Paul C; Reynolds, John D; Darimont, Chris T

    2013-01-01

    Scientific management of wildlife requires confronting the complexities of natural and social systems. Uncertainty poses a central problem. Whereas the importance of considering uncertainty has been widely discussed, studies of the effects of unaddressed uncertainty on real management systems have been rare. We examined the effects of outcome uncertainty and components of biological uncertainty on hunt management performance, illustrated with grizzly bears (Ursus arctos horribilis) in British Columbia, Canada. We found that both forms of uncertainty can have serious impacts on management performance. Outcome uncertainty alone--discrepancy between expected and realized mortality levels--led to excess mortality in 19% of cases (population-years) examined. Accounting for uncertainty around estimated biological parameters (i.e., biological uncertainty) revealed that excess mortality might have occurred in up to 70% of cases. We offer a general method for identifying targets for exploited species that incorporates uncertainty and maintains the probability of exceeding mortality limits below specified thresholds. Setting targets in our focal system using this method at thresholds of 25% and 5% probability of overmortality would require average target mortality reductions of 47% and 81%, respectively. Application of our transparent and generalizable framework to this or other systems could improve management performance in the presence of uncertainty.

  16. Wolves trigger a trophic cascade to berries as alternative food for grizzly bears.

    Science.gov (United States)

    Ripple, William J; Beschta, Robert L; Fortin, Jennifer K; Robbins, Charles T

    2015-05-01

    This is a Forum article in response to: Barber-Meyer, S. (2015) Trophic cascades from wolves to grizzly bears or changing abundance of bears and alternate foods? Journal of Animal Ecology, 83, doi: 10.1111/1365-2656.12338. We used multiple data sets and study areas as well as several lines of evidence to investigate potential trophic linkages in Yellowstone National Park. Our results suggest that a trophic cascade from wolves to elk to berry production to berry consumption by grizzly bears may now be underway in the Park.

  17. Temporal, spatial, and environmental influences on the demographics of grizzly bears in the Greater Yellowstone Ecosystem

    Science.gov (United States)

    Schwartz, Charles C.; Haroldson, Mark A.; White, Gary C.; Harris, Richard B.; Cherry, Steve; Keating, Kim A.; Moody, Dave; Servheen, Christopher

    2006-01-01

    During the past 2 decades, the grizzly bear (Ursus arctos) population in the Greater Yellowstone Ecosystem (GYE) has increased in numbers and expanded in range. Understanding temporal, environmental, and spatial variables responsible for this change is useful in evaluating what likely influenced grizzly bear demographics in the GYE and where future management efforts might benefit conservation and management. We used recent data from radio-marked bears to estimate reproduction (1983–2002) and survival (1983–2001); these we combined into models to evaluate demographic vigor (lambda [λ]). We explored the influence of an array of individual, temporal, and spatial covariates on demographic vigor.

  18. USE OF SULFUR AND NITROGEN STABLE ISOTOPES TO DETERMINE THE IMPORTANCE OF WHITEBARK PINE NUTS TO YELLOWSTONE GRIZZLY BEARS

    Science.gov (United States)

    Whitebark pine (Pinus albicaulis) is a masting species that produces relatively large, fat and protein-rich nuts that are consumed by grizzly bears (Ursus arctos horribilis). Trees produce abundant nut crops in some years and poor crops in other years. Grizzly bear survival in ...

  19. Nature vs. Nurture: Evidence for Social Learning of Conflict Behaviour in Grizzly Bears.

    Science.gov (United States)

    Morehouse, Andrea T; Graves, Tabitha A; Mikle, Nate; Boyce, Mark S

    2016-01-01

    The propensity for a grizzly bear to develop conflict behaviours might be a result of social learning between mothers and cubs, genetic inheritance, or both learning and inheritance. Using non-invasive genetic sampling, we collected grizzly bear hair samples during 2011-2014 across southwestern Alberta, Canada. We targeted private agricultural lands for hair samples at grizzly bear incident sites, defining an incident as an occurrence in which the grizzly bear caused property damage, obtained anthropogenic food, or killed or attempted to kill livestock or pets. We genotyped 213 unique grizzly bears (118 M, 95 F) at 24 microsatellite loci, plus the amelogenin marker for sex. We used the program COLONY to assign parentage. We evaluated 76 mother-offspring relationships and 119 father-offspring relationships. We compared the frequency of problem and non-problem offspring from problem and non-problem parents, excluding dependent offspring from our analysis. Our results support the social learning hypothesis, but not the genetic inheritance hypothesis. Offspring of problem mothers are more likely to be involved in conflict behaviours, while offspring from non-problem mothers are not likely to be involved in incidents or human-bear conflicts themselves (Barnard's test, p = 0.05, 62.5% of offspring from problem mothers were problem bears). There was no evidence that offspring are more likely to be involved in conflict behaviour if their fathers had been problem bears (Barnard's test, p = 0.92, 29.6% of offspring from problem fathers were problem bears). For the mother-offspring relationships evaluated, 30.3% of offspring were identified as problem bears independent of their mother's conflict status. Similarly, 28.6% of offspring were identified as problem bears independent of their father's conflict status. Proactive mitigation to prevent female bears from becoming problem individuals likely will help prevent the perpetuation of conflicts through social learning.

  20. Nature vs. nurture: Evidence for social learning of conflict behaviour in grizzly bears

    Science.gov (United States)

    Morehouse, Andrea T.; Graves, Tabitha A.; Mikle, Nathaniel; Boyce, Mark S.

    2016-01-01

    The propensity for a grizzly bear to develop conflict behaviours might be a result of social learning between mothers and cubs, genetic inheritance, or both learning and inheritance. Using non-invasive genetic sampling, we collected grizzly bear hair samples during 2011–2014 across southwestern Alberta, Canada. We targeted private agricultural lands for hair samples at grizzly bear incident sites, defining an incident as an occurrence in which the grizzly bear caused property damage, obtained anthropogenic food, or killed or attempted to kill livestock or pets. We genotyped 213 unique grizzly bears (118 M, 95 F) at 24 microsatellite loci, plus the amelogenin marker for sex. We used the program COLONY to assign parentage. We evaluated 76 mother-offspring relationships and 119 father-offspring relationships. We compared the frequency of problem and non-problem offspring from problem and non-problem parents, excluding dependent offspring from our analysis. Our results support the social learning hypothesis, but not the genetic inheritance hypothesis. Offspring of problem mothers are more likely to be involved in conflict behaviours, while offspring from non-problem mothers are not likely to be involved in incidents or human-bear conflicts themselves (Barnard’s test, p = 0.05, 62.5% of offspring from problem mothers were problem bears). There was no evidence that offspring are more likely to be involved in conflict behaviour if their fathers had been problem bears (Barnard’s test, p = 0.92, 29.6% of offspring from problem fathers were problem bears). For the mother-offspring relationships evaluated, 30.3% of offspring were identified as problem bears independent of their mother’s conflict status. Similarly, 28.6% of offspring were identified as problem bears independent of their father’s conflict status. Proactive mitigation to prevent female bears from becoming problem individuals likely will help prevent the perpetuation of conflicts through social learning.

  1. The impact of roads on the demography of grizzly bears in Alberta.

    Science.gov (United States)

    Boulanger, John; Stenhouse, Gordon B

    2014-01-01

    One of the principal factors that have reduced grizzly bear populations has been the creation of human access into grizzly bear habitat by roads built for resource extraction. Past studies have documented mortality and distributional changes of bears relative to roads but none have attempted to estimate the direct demographic impact of roads in terms of both survival rates, reproductive rates, and the interaction of reproductive state of female bears with survival rate. We applied a combination of survival and reproductive models to estimate demographic parameters for threatened grizzly bear populations in Alberta. Instead of attempting to estimate mean trend we explored factors which caused biological and spatial variation in population trend. We found that sex and age class survival was related to road density with subadult bears being most vulnerable to road-based mortality. A multi-state reproduction model found that females accompanied by cubs of the year and/or yearling cubs had lower survival rates compared to females with two year olds or no cubs. A demographic model found strong spatial gradients in population trend based upon road density. Threshold road densities needed to ensure population stability were estimated to further refine targets for population recovery of grizzly bears in Alberta. Models that considered lowered survival of females with dependant offspring resulted in lower road density thresholds to ensure stable bear populations. Our results demonstrate likely spatial variation in population trend and provide an example how demographic analysis can be used to refine and direct conservation measures for threatened species.

  2. Trichinellosis acquired in Nunavut, Canada in September 2009: meat from grizzly bear suspected.

    Science.gov (United States)

    Houzé, S; Ancelle, T; Matra, R; Boceno, C; Carlier, Y; Gajadhar, A A; Dupouy-Camet, J

    2009-11-05

    Five cases of trichinellosis with onset of symptoms in September 2009, were reported in France, and were probably linked to the consumption of meat from a grizzly bear in Cambridge Bay in Nunavut, Canada. Travellers should be aware of the risks of eating raw or rare meat products in arctic regions, particularly game meat such as bear or walrus meat.

  3. Moose, caribou, and grizzly bear distribution in relation to road traffic in Denali National Park, Alaska

    Science.gov (United States)

    Yost, A.C.; Wright, R.G.

    2001-01-01

    Park managers are concerned that moose (Alces alces), caribou (Rangifer tarandus), and grizzly bears (Ursus arctos) may be avoiding areas along the 130 km road through Denali National Park as a result of high traffic volume, thus decreasing opportunities for visitors to view wildlife. A wildlife monitoring system was developed in 1996 that used 19 landscape level viewsheds, stratified into four sections based on decreasing traffic along the road corridor. Data were collected from 22 samplings of all viewsheds during May-August in 1996 and 1997. In 1997, nine backcountry viewsheds were established in three different areas to determine whether density estimates for each species in the backcountry were higher than those for the same animals in similar road-corridor areas. Densities higher than those in the road corridor were found in one backcountry area for moose and in two backcountry areas for grizzly bears. None of the backcountry areas showed a higher density of caribou. We tested hypotheses that moose, caribou, and grizzly bear distributions were unrelated to the road and traffic. Moose sightings were lower than expected within 300 m of the road. More caribou and grizzly bears than expected occurred between 601 and 900 m from the road, while more moose and fewer caribou than expected occurred between 900 and 1200 m from the road. Bull moose in stratum 1 were distributed farther from the road than bulls and cows in stratum 4; cows in stratum 1 and bulls in stratum 2 were distributed farther from the road than cows in stratum 4. Grizzly bears in stratum 2 were distributed farther from the road than bears in stratum 3. The distribution of moose sightings suggests traffic avoidance, but the spatial pattern of preferred forage may have had more of an influence. Caribou and grizzly bear distributions indicated no pattern of traffic avoidance.

  4. Titin isoform switching is a major cardiac adaptive response in hibernating grizzly bears.

    Science.gov (United States)

    Nelson, O Lynne; Robbins, Charles T; Wu, Yiming; Granzier, Henk

    2008-07-01

    The hibernation phenomenon captures biological as well as clinical interests to understand how organs adapt. Here we studied how hibernating grizzly bears (Ursus arctos horribilis) tolerate extremely low heart rates without developing cardiac chamber dilation. We evaluated cardiac filling function in unanesthetized grizzly bears by echocardiography during the active and hibernating period. Because both collagen and titin are involved in altering diastolic function, we investigated both in the myocardium of active and hibernating grizzly bears. Heart rates were reduced from 84 beats/min in active bears to 19 beats/min in hibernating bears. Diastolic volume, stroke volume, and left ventricular ejection fraction were not different. However, left ventricular muscle mass was significantly lower (300 +/- 12 compared with 402 +/- 14 g; P = 0.003) in the hibernating bears, and as a result the diastolic volume-to-left ventricular muscle mass ratio was significantly greater. Early ventricular filling deceleration times (106.4 +/- 14 compared with 143.2 +/- 20 ms; P = 0.002) were shorter during hibernation, suggesting increased ventricular stiffness. Restrictive pulmonary venous flow patterns supported this conclusion. Collagen type I and III comparisons did not reveal differences between the two groups of bears. In contrast, the expression of titin was altered by a significant upregulation of the stiffer N2B isoform at the expense of the more compliant N2BA isoform. The mean ratio of N2BA to N2B titin was 0.73 +/- 0.07 in the active bears and decreased to 0.42 +/- 0.03 (P = 0.006) in the hibernating bears. The upregulation of stiff N2B cardiac titin is a likely explanation for the increased ventricular stiffness that was revealed by echocardiography, and we propose that it plays a role in preventing chamber dilation in hibernating grizzly bears. Thus our work identified changes in the alternative splicing of cardiac titin as a major adaptive response in hibernating grizzly

  5. Persistent organic pollutants in British Columbia grizzly bears: consequence of divergent diets.

    Science.gov (United States)

    Christensen, Jennie R; MacDuffee, Misty; Macdonald, Robie W; Whiticar, Michael; Ross, Peter S

    2005-09-15

    Nitrogen and carbon stable isotope signatures in growing hair reveal that while some British Columbia grizzly bears (Ursus arctos horribilis) rely entirely on terrestrial foods, others switch in late summer to returning Pacific salmon (Oncorynchus spp.). Implications for persistent organic pollutant (POP) concentrations and patterns measured in the two feeding groups of grizzly bears were profound. While the bears consuming a higher proportion of terrestrial vegetation ("interior" grizzlies) exhibited POP patterns dominated bythe more volatile organochlorine (OC) pesticides and the heavier polybrominated diphenyl ethers (PBDEs: e.g., BDE-209), the bears consuming salmon were dominated by the more bioaccumulative POPs (e.g., DDT, chlordanes, and BDE-47). The ocean-salmon-bear pathway appeared to preferentially select for those contaminants with intermediate partitioning strength from water into lipid (log Kow approximately 6.5). This pattern reflects an optimum contaminant log Kow range for atmospheric transport, deposition into the marine environment, uptake into marine biota, accumulation through the food web, and retention in the bear tissues. We estimate that salmon deliver 70% of all OC pesticides, up to 85% of the lower brominated PBDE congeners, and 90% of PCBs found in salmon-eating grizzly bears, thereby inextricably linking these terrestrial predators to contaminants from the North Pacific Ocean.

  6. Population growth of Yellowstone grizzly bears: Uncertainty and future monitoring

    Science.gov (United States)

    Harris, R.B.; White, Gary C.; Schwartz, C.C.; Haroldson, M.A.

    2007-01-01

    Grizzly bears (Ursus arctos) in the Greater Yellowstone Ecosystem of the US Rocky Mountains have recently increased in numbers, but remain vulnerable due to isolation from other populations and predicted reductions in favored food resources. Harris et al. (2006) projected how this population might fare in the future under alternative survival rates, and in doing so estimated the rate of population growth, 1983–2002. We address issues that remain from that earlier work: (1) the degree of uncertainty surrounding our estimates of the rate of population change (λ); (2) the effect of correlation among demographic parameters on these estimates; and (3) how a future monitoring system using counts of females accompanied by cubs might usefully differentiate between short-term, expected, and inconsequential fluctuations versus a true change in system state. We used Monte Carlo re-sampling of beta distributions derived from the demographic parameters used by Harris et al. (2006) to derive distributions of λ during 1983–2002 given our sampling uncertainty. Approximate 95% confidence intervals were 0.972–1.096 (assuming females with unresolved fates died) and 1.008–1.115 (with unresolved females censored at last contact). We used well-supported models of Haroldson et al. (2006) and Schwartz et al. (2006a,b,c) to assess the strength of correlations among demographic processes and the effect of omitting them in projection models. Incorporating correlations among demographic parameters yielded point estimates of λ that were nearly identical to those from the earlier model that omitted correlations, but yielded wider confidence intervals surrounding λ. Finally, we suggest that fitting linear and quadratic curves to the trend suggested by the estimated number of females with cubs in the ecosystem, and using AICc model weights to infer population sizes and λ provides an objective means to monitoring approximate population trajectories in addition to demographic

  7. Persistent or not persistent? Polychlorinated biphenyls are readily depurated by grizzly bears (Ursus arctos horribilis).

    Science.gov (United States)

    Christensen, Jennie R; Letcher, Robert J; Ross, Peter S

    2009-10-01

    Major pharmacokinetic processes influencing polychlorinated biphenyl (PCB) accumulation in mammals include uptake, biotransformation, respiration, and excretion. We characterized some of the factors underlying PCB accumulation/loss by evaluating PCB concentrations and patterns in pre- and posthibernation grizzly bears (Ursus arctos horribilis) and their prey. The PCB congeners with vicinal meta- and para-chlorine unsubstituted hydrogen positions consistently showed loss both before and during hibernation, supporting the idea of a dominant role for biotransformation. Retention of all other studied congeners relative to that of PCB 194 varied widely (from bears do not eat or excrete. We estimate that grizzly bears retain less than 10% of total PCBs taken up from their diet. Our results suggest that for grizzly bears, depuration of PCBs via biotransformation is important (explaining approximately 40% of loss), but that nonbiotransformation processes, such as excretion, may be more important (explaining approximately 60% of loss). These findings, together with the approximately 91% loss of the persistent PCB 153 congener relative to PCB 194 in grizzly bears, raise important questions about how one defines persistence of PCBs in wildlife and may have bearing on the interpretation of food-web biomagnification studies.

  8. Grizzly Bear Noninvasive Genetic Tagging Surveys: Estimating the Magnitude of Missed Detections.

    Science.gov (United States)

    Fisher, Jason T; Heim, Nicole; Code, Sandra; Paczkowski, John

    2016-01-01

    Sound wildlife conservation decisions require sound information, and scientists increasingly rely on remotely collected data over large spatial scales, such as noninvasive genetic tagging (NGT). Grizzly bears (Ursus arctos), for example, are difficult to study at population scales except with noninvasive data, and NGT via hair trapping informs management over much of grizzly bears' range. Considerable statistical effort has gone into estimating sources of heterogeneity, but detection error-arising when a visiting bear fails to leave a hair sample-has not been independently estimated. We used camera traps to survey grizzly bear occurrence at fixed hair traps and multi-method hierarchical occupancy models to estimate the probability that a visiting bear actually leaves a hair sample with viable DNA. We surveyed grizzly bears via hair trapping and camera trapping for 8 monthly surveys at 50 (2012) and 76 (2013) sites in the Rocky Mountains of Alberta, Canada. We used multi-method occupancy models to estimate site occupancy, probability of detection, and conditional occupancy at a hair trap. We tested the prediction that detection error in NGT studies could be induced by temporal variability within season, leading to underestimation of occupancy. NGT via hair trapping consistently underestimated grizzly bear occupancy at a site when compared to camera trapping. At best occupancy was underestimated by 50%; at worst, by 95%. Probability of false absence was reduced through successive surveys, but this mainly accounts for error imparted by movement among repeated surveys, not necessarily missed detections by extant bears. The implications of missed detections and biased occupancy estimates for density estimation-which form the crux of management plans-require consideration. We suggest hair-trap NGT studies should estimate and correct detection error using independent survey methods such as cameras, to ensure the reliability of the data upon which species management and

  9. Predatory behavior of grizzly bears feeding on elk calves in Yellowstone National Park

    Science.gov (United States)

    French, Steven P.; French, Marilynn G.

    1990-01-01

    Grizzly bears (Ursus arctos horribilis) were observed preying on elk calves (Cervus elaphus) on 60 occasions in Yellowstone National Park, with 29 confirmed kills. Some bears were deliberate predators and effectively preyed on elk calves for short periods each spring, killing up to 1 calf daily. Primary hunting techniques were searching and chasing although some bears used a variety of techniques during a single hunt. They hunted both day and night and preyed on calves in the open and in the woods. Excess killing occurred when circumstances permitted. One bear caught 5 calves in a 15-minute interval. Elk used a variety of antipredator defenses and occasionally attacked predacious bears. The current level of this feeding behavior appears to be greater than previously reported. This is probably related to the increased availability of calves providing a greater opportunity for learning, and the adaptation of a more predatory behavior by some grizzly bears in Yellowstone.

  10. Interactions between wolves and female grizzly bears with cubs in Yellowstone National Park

    Science.gov (United States)

    Gunther, Kerry A.; Smith, Douglas W.

    2004-01-01

    Gray wolves (Canis lupus) were extirpated from Yellowstone National Park (YNP) by the 1920s through predator control actions (Murie 1940,Young and Goldman 1944, Weaver 1978), then reintroduced into the park from 1995 to 1996 to restore ecological integrity and adhere to legal mandates (Bangs and Fritts 1996, Phillips and Smith 1996, Smith et al. 2000). Prior to reintroduction, the potential effects of wolves on the region’s threatened grizzly bear (Ursus arctos) population were evaluated (Servheen and Knight 1993). In areas where wolves and grizzly bears are sympatric, interspecific killing by both species occasionally occurs (Ballard 1980, 1982; Hayes and Baer 1992). Most agonistic interactions between wolves and grizzly bears involve defense of young or competition for carcasses (Murie 1944, 1981; Ballard 1982; Hornbeck and Horejsi 1986; Hayes and Mossop 1987; Kehoe 1995; McNulty et al. 2001). Servheen and Knight (1993) predicted that reintroduced wolves could reduce the frequency of winter-killed and disease-killed ungulates available for bears to scavenge, and that grizzly bears would occasionally usurp wolf-killed ungulate carcasses. Servheen and Knight (1993) hypothesized that interspecific killing and competition for carcasses would have little or no population level effect on either species.

  11. Genetic analysis of individual origins supports isolation of grizzly bears in the Greater Yellowstone Ecosystem

    Science.gov (United States)

    Haroldson, Mark A.; Schwartz, Charles; Kendall, Katherine C.; Gunther, Kerry A.; Moody, David S.; Frey, Kevin L.; Paetkau, David

    2010-01-01

    The Greater Yellowstone Ecosystem (GYE) supports the southernmost of the 2 largest remaining grizzly bear (Ursus arctos) populations in the contiguous United States. Since the mid-1980s, this population has increased in numbers and expanded in range. However, concerns for its long-term genetic health remain because of its presumed continued isolation. To test the power of genetic methods for detecting immigrants, we generated 16-locus microsatellite genotypes for 424 individual grizzly bears sampled in the GYE during 1983–2007. Genotyping success was high (90%) and varied by sample type, with poorest success (40%) for hair collected from mortalities found ≥1 day after death. Years of storage did not affect genotyping success. Observed heterozygosity was 0.60, with a mean of 5.2 alleles/marker. We used factorial correspondence analysis (Program GENETIX) and Bayesian clustering (Program STRUCTURE) to compare 424 GYE genotypes with 601 existing genotypes from grizzly bears sampled in the Northern Continental Divide Ecosystem (NCDE) (FST  =  0.096 between GYE and NCDE). These methods correctly classified all sampled individuals to their population of origin, providing no evidence of natural movement between the GYE and NCDE. Analysis of 500 simulated first-generation crosses suggested that over 95% of such bears would also be detectable using our 16-locus data set. Our approach provides a practical method for detecting immigration in the GYE grizzly population. We discuss estimates for the proportion of the GYE population sampled and prospects for natural immigration into the GYE.

  12. Serological survey of selected canine viral pathogens and zoonoses in grizzly bears (Ursus arctos horribilis) and black bears (Ursus americanus) from Alaska.

    Science.gov (United States)

    Chomel, B B; Kasten, R W; Chappuis, G; Soulier, M; Kikuchi, Y

    1998-12-01

    Between 1988 and 1991, 644 serum samples were collected from 480 grizzly bears (Ursus arctos horribilis) and 40 black bears (Ursus americanus) from Alaska, United States of America, and were tested for selected canine viral infections and zoonoses. Antibody prevalence in grizzly bears was 0% for parvovirus, 8.3% (40/480) for distemper, 14% (68/480) for infectious hepatitis, 16.5% (79/480) for brucellosis, 19% (93/480) for tularaemia and 47% (225/478) for trichinellosis. In black bears, prevalence ranged from 0% for distemper and parvovirus to 27.5% for trichinellosis and 32% for tularaemia. Antibody prevalence for brucellosis (2.5%) and tularaemia (32%) were identical for grizzly bears and black bears from the geographical area of interior Alaska. Links between differences in prevalence and the origin of the grizzly bears were observed. Antibodies to canine distemper virus and infectious hepatitis virus were mainly detected in grizzly bears from Kodiak Island and the Alaskan Peninsula. Brucellosis antibodies were prevalent in grizzly bears from western and northern Alaska, whereas tularaemia antibodies were detected in grizzly bears from interior Alaska and the Arctic. There was a strong gradient for antibodies to Trichinella spp. from southern to northern Alaska. For most diseases, antibody prevalence increased with age. However, for several infections, no antibodies were detected in grizzly bears aged from 0 to 2 years, in contrast to the presence of those infections in black bears. Grizzly bears served as excellent sentinels for surveillance of zoonotic infections in wildlife in Alaska.

  13. The impact of roads on the demography of grizzly bears in Alberta.

    Directory of Open Access Journals (Sweden)

    John Boulanger

    Full Text Available One of the principal factors that have reduced grizzly bear populations has been the creation of human access into grizzly bear habitat by roads built for resource extraction. Past studies have documented mortality and distributional changes of bears relative to roads but none have attempted to estimate the direct demographic impact of roads in terms of both survival rates, reproductive rates, and the interaction of reproductive state of female bears with survival rate. We applied a combination of survival and reproductive models to estimate demographic parameters for threatened grizzly bear populations in Alberta. Instead of attempting to estimate mean trend we explored factors which caused biological and spatial variation in population trend. We found that sex and age class survival was related to road density with subadult bears being most vulnerable to road-based mortality. A multi-state reproduction model found that females accompanied by cubs of the year and/or yearling cubs had lower survival rates compared to females with two year olds or no cubs. A demographic model found strong spatial gradients in population trend based upon road density. Threshold road densities needed to ensure population stability were estimated to further refine targets for population recovery of grizzly bears in Alberta. Models that considered lowered survival of females with dependant offspring resulted in lower road density thresholds to ensure stable bear populations. Our results demonstrate likely spatial variation in population trend and provide an example how demographic analysis can be used to refine and direct conservation measures for threatened species.

  14. Grizzly bear (Ursus arctos horribilis) locomotion: gaits and ground reaction forces.

    Science.gov (United States)

    Shine, Catherine L; Penberthy, Skylar; Robbins, Charles T; Nelson, O Lynne; McGowan, Craig P

    2015-10-01

    Locomotion of plantigrade generalists has been relatively little studied compared with more specialised postures even though plantigrady is ancestral among quadrupeds. Bears (Ursidae) are a representative family for plantigrade carnivorans, they have the majority of the morphological characteristics identified for plantigrade species, and they have the full range of generalist behaviours. This study compared the locomotion of adult grizzly bears (Ursus arctos horribilis Linnaeus 1758), including stride parameters, gaits and analysis of three-dimensional ground reaction forces, with that of previously studied quadrupeds. At slow to moderate speeds, grizzly bears use walks, running walks and canters. Vertical ground reaction forces demonstrated the typical M-shaped curve for walks; however, this was significantly more pronounced in the hindlimb. The rate of force development was also significantly higher for the hindlimbs than for the forelimbs at all speeds. Mediolateral forces were significantly higher than would be expected for a large erect mammal, almost to the extent of a sprawling crocodilian. There may be morphological or energetic explanations for the use of the running walk rather than the trot. The high medial forces (produced from a lateral push by the animal) could be caused by frontal plane movement of the carpus and elbow by bears. Overall, while grizzly bears share some similarities with large cursorial species, their locomotor kinetics have unique characteristics. Additional studies are needed to determine whether these characters are a feature of all bears or plantigrade species.

  15. Possible effects of elk harvest on fall distribution of grizzly bears in the Greater Yellowstone Ecosystem

    Science.gov (United States)

    Haroldson, M.A.; Schwartz, C.C.; Cherry, S.; Moody, D.

    2004-01-01

     The tradition of early elk (Cervus elaphus) hunting seasons adjacent to Yellowstone National Park (YNP), USA, provides grizzly bears (Ursus arctos horribilis) with ungulate remains left by hunters. We investigated the fall (Aug–Oct) distribution of grizzly bears relative to the boundaries of YNP and the opening of September elk hunting seasons. Based on results from exact tests of conditional independence, we estimated the odds of radiomarked bears being outside YNP during the elk hunt versus before the hunt. Along the northern boundary, bears were 2.40 times more likely to be outside YNP during the hunt in good whitebark pine (Pinus albicaulis) seed-crop years and 2.72 times more likely in poor seed-crop years. The level of confidence associated with 1-sided confidence intervals with a lower endpoint of 1 was approximately 94% in good seed-crop years and 61% in poor years. Along the southern boundary of YNP, radiomarked bears were 2.32 times more likely to be outside the park during the hunt in good whitebark pine seed-crop years and 4.35 times more likely in poor seed-crop years. The level of confidence associated with 1-sided confidence intervals with a lower endpoint of 1 was approximately 93% in both cases. Increased seasonal bear densities and human presence in early hunt units increases potential for conflicts between bears and hunters. Numbers of reported hunting-related grizzly bear mortalities have increased in the Greater Yellowstone Ecosystem (GYE) during the last decade, and nearly half of this increase is due to bear deaths occurring in early hunt units during September. Human-caused grizzly bear mortality thresholds established by the U.S. Fish and Wildlife Service (USFWS) have not been exceeded in recent years. This is because agency actions have reduced other sources of human-caused mortalities, and because population parameters that mortality thresholds are based on have increased. Agencies must continue to monitor and manage hunter

  16. Estimating grizzly and black bear population abundance and trend in Banff National Park using noninvasive genetic sampling.

    Directory of Open Access Journals (Sweden)

    Michael A Sawaya

    Full Text Available We evaluated the potential of two noninvasive genetic sampling methods, hair traps and bear rub surveys, to estimate population abundance and trend of grizzly (Ursus arctos and black bear (U. americanus populations in Banff National Park, Alberta, Canada. Using Huggins closed population mark-recapture models, we obtained the first precise abundance estimates for grizzly bears (N= 73.5, 95% CI = 64-94 in 2006; N= 50.4, 95% CI = 49-59 in 2008 and black bears (N= 62.6, 95% CI = 51-89 in 2006; N= 81.8, 95% CI = 72-102 in 2008 in the Bow Valley. Hair traps had high detection rates for female grizzlies, and male and female black bears, but extremely low detection rates for male grizzlies. Conversely, bear rubs had high detection rates for male and female grizzlies, but low rates for black bears. We estimated realized population growth rates, lambda, for grizzly bear males (λ= 0.93, 95% CI = 0.74-1.17 and females (λ= 0.90, 95% CI = 0.67-1.20 using Pradel open population models with three years of bear rub data. Lambda estimates are supported by abundance estimates from combined hair trap/bear rub closed population models and are consistent with a system that is likely driven by high levels of human-caused mortality. Our results suggest that bear rub surveys would provide an efficient and powerful means to inventory and monitor grizzly bear populations in the Central Canadian Rocky Mountains.

  17. Estimating grizzly and black bear population abundance and trend in Banff National Park using noninvasive genetic sampling.

    Science.gov (United States)

    Sawaya, Michael A; Stetz, Jeffrey B; Clevenger, Anthony P; Gibeau, Michael L; Kalinowski, Steven T

    2012-01-01

    We evaluated the potential of two noninvasive genetic sampling methods, hair traps and bear rub surveys, to estimate population abundance and trend of grizzly (Ursus arctos) and black bear (U. americanus) populations in Banff National Park, Alberta, Canada. Using Huggins closed population mark-recapture models, we obtained the first precise abundance estimates for grizzly bears (N= 73.5, 95% CI = 64-94 in 2006; N= 50.4, 95% CI = 49-59 in 2008) and black bears (N= 62.6, 95% CI = 51-89 in 2006; N= 81.8, 95% CI = 72-102 in 2008) in the Bow Valley. Hair traps had high detection rates for female grizzlies, and male and female black bears, but extremely low detection rates for male grizzlies. Conversely, bear rubs had high detection rates for male and female grizzlies, but low rates for black bears. We estimated realized population growth rates, lambda, for grizzly bear males (λ= 0.93, 95% CI = 0.74-1.17) and females (λ= 0.90, 95% CI = 0.67-1.20) using Pradel open population models with three years of bear rub data. Lambda estimates are supported by abundance estimates from combined hair trap/bear rub closed population models and are consistent with a system that is likely driven by high levels of human-caused mortality. Our results suggest that bear rub surveys would provide an efficient and powerful means to inventory and monitor grizzly bear populations in the Central Canadian Rocky Mountains.

  18. Density, distribution, and genetic structure of grizzly bears in the Cabinet-Yaak Ecosystem

    Science.gov (United States)

    Macleod, Amy C.; Boyd, Kristina L; Boulanger, John; Royle, J. Andrew; Kasworm, Wayne F.; Paetkau, David; Proctor, Michael F; Annis, Kim; Graves, Tabitha A.

    2016-01-01

    The conservation status of the 2 threatened grizzly bear (Ursus arctos) populations in the Cabinet-Yaak Ecosystem (CYE) of northern Montana and Idaho had remained unchanged since designation in 1975; however, the current demographic status of these populations was uncertain. No rigorous data on population density and distribution or analysis of recent population genetic structure were available to measure the effectiveness of conservation efforts. We used genetic detection data from hair corral, bear rub, and opportunistic sampling in traditional and spatial capture–recapture models to generate estimates of abundance and density of grizzly bears in the CYE. We calculated mean bear residency on our sampling grid from telemetry data using Huggins and Pledger models to estimate the average number of bears present and to correct our superpopulation estimates for lack of geographic closure. Estimated grizzly bear abundance (all sex and age classes) in the CYE in 2012 was 48–50 bears, approximately half the population recovery goal. Grizzly bear density in the CYE (4.3–4.5 grizzly bears/1,000 km2) was among the lowest of interior North American populations. The sizes of the Cabinet (n = 22–24) and Yaak (n = 18–22) populations were similar. Spatial models produced similar estimates of abundance and density with comparable precision without requiring radio-telemetry data to address assumptions of geographic closure. The 2 populations in the CYE were demographically and reproductively isolated from each other and the Cabinet population was highly inbred. With parentage analysis, we documented natural migrants to the Cabinet and Yaak populations by bears born to parents in the Selkirk and Northern Continental Divide populations. These events supported data from other sources suggesting that the expansion of neighboring populations may eventually help sustain the CYE populations. However, the small size, isolation, and inbreeding documented by this study

  19. Yellowstone grizzly bear mortality, human habituation, and whitebark pine seed crops

    Science.gov (United States)

    Mattson, David J.; Blanchard, Bonnie M.; Knight, Richard R.

    1992-01-01

    The Yellowstone grizzly bear (Ursus arctos horribilis) population may be extirpated during the next 100-200 years unless mortality rates stabilize and remain at acceptable low levels. Consequently, we analyzed relationships between Yellowstone grizzly bear mortality and frequency of human habituation among bears and size of the whitebark pine (Pinus albicaulis) seed crop. During years of large seed crops, bears used areas within 5 km of roads and 8 km of developments half as intensively as during years of small seed crops because whitebark pine's high elevation distribution is typically remote from human facilities. On average, management trappings of bears were 6.2 times higher, mortality of adult females 2.3 times higher, and mortality of subadult males 3.3 times higher during years of small seed crops. We hypothesize that high mortality of adult females and subadult males during small seed crop years was a consequence of their tendency to range closest (of all sex-age cohorts) to human facilities; they also had a higher frequency of human habituation compared with adult males. We also hypothesize that low morality among subadult females during small seed crop years was a result of fewer energetic stressors compared with adult females and greater familiarity with their range compared with subadult males; mortality was low even though they ranged close to humans and exhibited a high frequency of human habituation. Human-habituated and food-conditioned bears were 2.9 times as likely to range within 4 km of developments and 3.1 times as often killed by humans compared with nonhabituated bears. We argue that destruction of habituated bears that use native foods near humans results in a decline in the overall ability of bears to use available habitat; and that the number and extent of human facilities in occupied grizzly bear habitat needs to be minimized unless habituated bears are preserved and successful ways to manage the associated risks to humans are developed.

  20. Whitebark pine, population density, and home-range size of grizzly bears in the greater yellowstone ecosystem.

    Science.gov (United States)

    Bjornlie, Daniel D; Van Manen, Frank T; Ebinger, Michael R; Haroldson, Mark A; Thompson, Daniel J; Costello, Cecily M

    2014-01-01

    Changes in life history traits of species can be an important indicator of potential factors influencing populations. For grizzly bears (Ursus arctos) in the Greater Yellowstone Ecosystem (GYE), recent decline of whitebark pine (WBP; Pinus albicaulis), an important fall food resource, has been paired with a slowing of population growth following two decades of robust population increase. These observations have raised questions whether resource decline or density-dependent processes may be associated with changes in population growth. Distinguishing these effects based on changes in demographic rates can be difficult. However, unlike the parallel demographic responses expected from both decreasing food availability and increasing population density, we hypothesized opposing behavioral responses of grizzly bears with regard to changes in home-range size. We used the dynamic changes in food resources and population density of grizzly bears as a natural experiment to examine hypotheses regarding these potentially competing influences on grizzly bear home-range size. We found that home-range size did not increase during the period of whitebark pine decline and was not related to proportion of whitebark pine in home ranges. However, female home-range size was negatively associated with an index of population density. Our data indicate that home-range size of grizzly bears in the GYE is not associated with availability of WBP, and, for female grizzly bears, increasing population density may constrain home-range size.

  1. Whitebark pine, population density, and home-range size of grizzly bears in the greater yellowstone ecosystem.

    Directory of Open Access Journals (Sweden)

    Daniel D Bjornlie

    Full Text Available Changes in life history traits of species can be an important indicator of potential factors influencing populations. For grizzly bears (Ursus arctos in the Greater Yellowstone Ecosystem (GYE, recent decline of whitebark pine (WBP; Pinus albicaulis, an important fall food resource, has been paired with a slowing of population growth following two decades of robust population increase. These observations have raised questions whether resource decline or density-dependent processes may be associated with changes in population growth. Distinguishing these effects based on changes in demographic rates can be difficult. However, unlike the parallel demographic responses expected from both decreasing food availability and increasing population density, we hypothesized opposing behavioral responses of grizzly bears with regard to changes in home-range size. We used the dynamic changes in food resources and population density of grizzly bears as a natural experiment to examine hypotheses regarding these potentially competing influences on grizzly bear home-range size. We found that home-range size did not increase during the period of whitebark pine decline and was not related to proportion of whitebark pine in home ranges. However, female home-range size was negatively associated with an index of population density. Our data indicate that home-range size of grizzly bears in the GYE is not associated with availability of WBP, and, for female grizzly bears, increasing population density may constrain home-range size.

  2. Use of pine nuts by grizzly and black bears in the Yellowstone area

    Science.gov (United States)

    Kendall, Katherine C.

    1983-01-01

    The large seeds (pine nuts) of whitebark pine are commonly eaten in the spring (March-May) and fall (September-November) by grizzly and black bears in Yellowstone National Park and adjacent areas (Craighead and Craighead 1972, Blanchard 1978, Mealey 1980) and western Montana (Tisch 1961; J. Sumner and J. J. Craighead, unpubl. rep., Montant Coop. Wildl. Res. Unit, Univ. Montana, Missoula, 1973). Similar nuts from limber pine are eaten by grizzly bears on the east Rocky Mountain Front of northwestern Montana (Schallenberger and Jonkel, annual rep., Border Grizzly Project, Univ. Montana, Missoula, 1980). The nuts of the European stone pine (P. cembra) are an important food for brown bears (U. arctos) throughout the taiga zone in the Soviet Union (Pavlov and Zhdanov 1972, Ustinov 1972, Yazan 1972). Both the production of whitebark pine cones (Forcella 1977, Blanchard 1978, Mealey 1980) and the quantity of nuts consumed by bears vary annually (Mealey 1975, Blancard 1978). Pine nuts are also an important food for red squirrels in whitebark forests. In fall, squirrels remove cones from trees and cache them in middens. Bears as well as other mammalian and avian seed predators compete with squirrels for whitebark nuts (Forcella 1977, Tomback 1977). Confusion about the ripening process of whitebark pine cones has resulted in errors in the literature on the availability of pine nuts as a bear food. Whitebark cones are indehiscent and do not disintegrate (Tomback 1981). Vertebrate foraging probably leaves few, if any, seed-bearing cones on trees by late fall; the cones remaining abscise sometime thereafter (Tomback 1981). Because cones do not abscise or release their seed in fall, bears may obtain pine nuts in 2 ways. Black bears may climb whitebark pine trees and break off cone-bearing brnahces to feed on cones (Tisch 1961, Mealey 1975, Forcella 1977); or both black bears and grizzly bears may raid squirrel caches to feed on pine nuts (Tisch 1961, Craighead and Craighead 1972

  3. Idiosyncratic responses of grizzly bear habitat to climate change based on projected food resource changes.

    Science.gov (United States)

    Roberts, David R; Nielsen, Scott E; Stenhouse, Gordon B

    2014-07-01

    Climate change vulnerability assessments for species of conservation concern often use species distribution and ecological niche modeling to project changes in habitat. One of many assumptions of these approaches is that food web dependencies are consistent in time and environmental space. Species at higher trophic levels that rely on the availability of species at lower trophic levels as food may be sensitive to extinction cascades initiated by changes in the habitat of key food resources. Here we assess climate change vulnerability for Ursus arctos (grizzly bears) in the southern Canadian Rocky Mountains using projected changes to 17 of the most commonly consumed plant food items. We used presence-absence information from 7088 field plots to estimate ecological niches and to project changes in future distributions of each species. Model projections indicated idiosyncratic responses among food items. Many food items persisted or even increased, although several species were found to be vulnerable based on declines or geographic shifts in suitable habitat. These included Hedysarum alpinum (alpine sweet vetch), a critical spring and autumn root-digging resource when little else is available. Potential habitat loss was also identified for three fruiting species of lower importance to bears: Empetrum nigrum (crowberry), Vaccinium scoparium (grouseberry), and Fragaria virginiana (strawberry). A general trend towards uphill migration of bear foods may result in higher vulnerability to bear populations at low elevations, which are also those that are most likely to have human-bear conflict problems. Regardless, a wide diet breadth of grizzly bears, as well as wide environmental niches of most food items, make climate change a much lower threat to grizzly bears than other bear species such as polar bears and panda bears. We cannot exclude, however, future alterations in human behavior and land use resulting from climate change that may reduce survival rates.

  4. Landscape conditions predisposing grizzly bears to conflicts on private agricultural lands in the western USA

    Science.gov (United States)

    Wilson, S.M.; Madel, M.J.; Mattson, D.J.; Graham, J.M.; Merrill, T.

    2006-01-01

    We used multiple logistic regression to model how different landscape conditions contributed to the probability of human-grizzly bear conflicts on private agricultural ranch lands. We used locations of livestock pastures, traditional livestock carcass disposal areas (boneyards), beehives, and wetland-riparian associated vegetation to model the locations of 178 reported human-grizzly bear conflicts along the Rocky Mountain East Front, Montana, USA during 1986-2001. We surveyed 61 livestock producers in the upper Teton watershed of north-central Montana, to collect spatial and temporal data on livestock pastures, boneyards, and beehives for the same period, accounting for changes in livestock and boneyard management and beehive location and protection, for each season. We used 2032 random points to represent the null hypothesis of random location relative to potential explanatory landscape features, and used Akaike's Information Criteria (AIC/AICC) and Hosmer-Lemeshow goodness-of-fit statistics for model selection. We used a resulting "best" model to map contours of predicted probabilities of conflict, and used this map for verification with an independent dataset of conflicts to provide additional insights regarding the nature of conflicts. The presence of riparian vegetation and distances to spring, summer, and fall sheep or cattle pastures, calving and sheep lambing areas, unmanaged boneyards, and fenced and unfenced beehives were all associated with the likelihood of human-grizzly bear conflicts. Our model suggests that collections of attractants concentrated in high quality bear habitat largely explain broad patterns of human-grizzly bear conflicts on private agricultural land in our study area. ?? 2005 Elsevier Ltd. All rights reserved.

  5. Use of sulfur and nitrogen stable isotopes to determine the importance of whitebark pine nuts to Yellowstone grizzly bears

    Science.gov (United States)

    Felicetti, L.A.; Schwartz, C.C.; Rye, R.O.; Haroldson, M.A.; Gunther, K.A.; Phillips, D.L.; Robbins, C.T.

    2003-01-01

    Whitebark pine (Pinus albicaulis) is a masting species that produces relatively large, fat- and protein-rich nuts that are consumed by grizzly bears (Ursus arctos horribilis). Trees produce abundant nut crops in some years and poor crops in other years. Grizzly bear survival in the Greater Yellowstone Ecosystem is strongly linked to variation in pine-nut availability. Because whitebark pine trees are infected with blister rust (Cronartium ribicola), an exotic fungus that has killed the species throughout much of its range in the northern Rocky Mountains, we used stable isotopes to quantify the importance of this food resource to Yellowstone grizzly bears while healthy populations of the trees still exist. Whitebark pine nuts have a sulfur-isotope signature (9.2 ?? 1.3??? (mean ?? 1 SD)) that is distinctly different from those of all other grizzly bear foods (ranging from 1.9 ?? 1.7??? for all other plants to 3.1 ?? 2.6??? for ungulates). Feeding trials with captive grizzly bears were used to develop relationships between dietary sulfur-, carbon-, and nitrogen-isotope signatures and those of bear plasma. The sulfur and nitrogen relationships were used to estimate the importance of pine nuts to free-ranging grizzly bears from blood and hair samples collected between 1994 and 2001. During years of poor pine-nut availability, 72% of the bears made minimal use of pine nuts. During years of abundant cone availability, 8 ?? 10% of the bears made minimal use of pine nuts, while 67 ?? 19% derived over 51% of their assimilated sulfur and nitrogen (i.e., protein) from pine nuts. Pine nuts and meat are two critically important food resources for Yellowstone grizzly bears.

  6. Comparison of methanol and isopropanol as wash solvents for determination of hair cortisol concentration in grizzly bears and polar bears.

    Science.gov (United States)

    Kroshko, Thomas; Kapronczai, Luciene; Cattet, Marc R L; Macbeth, Bryan J; Stenhouse, Gordon B; Obbard, Martyn E; Janz, David M

    2017-01-01

    Methodological differences among laboratories are recognized as significant sources of variation in quantification of hair cortisol concentration (HCC). An important step in processing hair, particularly when collected from wildlife, is the choice of solvent used to remove or "wash" external hair shaft cortisol prior to quantification of HCC. The present study systematically compared methanol and isopropanol as wash solvents for their efficiency at removing external cortisol without extracting internal hair shaft cortisol in samples collected from free-ranging grizzly bears and polar bears. Cortisol concentrations in solvents and hair were determined in each of one to eight washes of hair with each solvent independently. •There were no significant decreases in internal hair shaft cortisol among all eight washes for either solvent, although methanol removed detectable hair surface cortisol after one wash in grizzly bear hair whereas hair surface cortisol was detected in all eight isopropanol washes.•There were no significant differences in polar bear HCC washed one to eight times with either solvent, but grizzly bear HCC was significantly greater in hair washed with isopropanol compared to methanol.•There were significant differences in HCC quantified using different commercial ELISA kits commonly used for HCC determinations.

  7. Modeling survival: application of the Andersen-Gill model to Yellowstone grizzly bears

    Science.gov (United States)

    Johnson, Christopher J.; Boyce, Mark S.; Schwartz, Charles C.; Haroldson, Mark A.

    2004-01-01

     Wildlife ecologists often use the Kaplan-Meier procedure or Cox proportional hazards model to estimate survival rates, distributions, and magnitude of risk factors. The Andersen-Gill formulation (A-G) of the Cox proportional hazards model has seen limited application to mark-resight data but has a number of advantages, including the ability to accommodate left-censored data, time-varying covariates, multiple events, and discontinuous intervals of risks. We introduce the A-G model including structure of data, interpretation of results, and assessment of assumptions. We then apply the model to 22 years of radiotelemetry data for grizzly bears (Ursus arctos) of the Greater Yellowstone Grizzly Bear Recovery Zone in Montana, Idaho, and Wyoming, USA. We used Akaike's Information Criterion (AICc) and multi-model inference to assess a number of potentially useful predictive models relative to explanatory covariates for demography, human disturbance, and habitat. Using the most parsimonious models, we generated risk ratios, hypothetical survival curves, and a map of the spatial distribution of high-risk areas across the recovery zone. Our results were in agreement with past studies of mortality factors for Yellowstone grizzly bears. Holding other covariates constant, mortality was highest for bears that were subjected to repeated management actions and inhabited areas with high road densities outside Yellowstone National Park. Hazard models developed with covariates descriptive of foraging habitats were not the most parsimonious, but they suggested that high-elevation areas offered lower risks of mortality when compared to agricultural areas.

  8. Immobilization of grizzly bears (Ursus arctos) with dexmedetomidine, tiletamine, and zolazepam.

    Science.gov (United States)

    Teisberg, Justin E; Farley, Sean D; Nelson, O Lynne; Hilderbrand, Grant V; Madel, Michael J; Owen, Patricia A; Erlenbach, Joy A; Robbins, Charles T

    2014-01-01

    Safe and effective immobilization of grizzly bears (Ursus arctos) is essential for research and management. Fast induction of anesthesia, maintenance of healthy vital rates, and predictable recoveries are priorities. From September 2010 to May 2012, we investigated these attributes in captive and wild grizzly bears anesthetized with a combination of a reversible α2 agonist (dexmedetomidine [dexM], the dextrorotatory enantiomer of medetomidine) and a nonreversible N-methyl-d-aspartate (NMDA) agonist and tranquilizer (tiletamine and zolazepam [TZ], respectively). A smaller-than-expected dose of the combination (1.23 mg tiletamine, 1.23 mg zolazepam, and 6.04 µg dexmedetomidine per kg bear) produced reliable, fast ataxia (3.7 ± 0.5 min, x̄±SE) and workable anesthesia (8.1 ± 0.6 min) in captive adult grizzly bears. For wild bears darted from a helicopter, a dose of 2.06 mg tiletamine, 2.06 mg zolazepam, and 10.1 µg dexmedetomidine/kg produced ataxia in 2.5 ± 0.3 min and anesthesia in 5.5 ± 1.0 min. Contrary to published accounts of bear anesthesia with medetomidine, tiletamine, and zolazepam, this combination did not cause hypoxemia or hypoventilation, although mild bradycardia (bears during the active season. With captive bears, effective dose rates during hibernation were approximately half those during the active season. The time to first signs of recovery after the initial injection of dexMTZ was influenced by heart rate (Pgrizzly bears, especially during helicopter capture operations.

  9. The Bear Facts: Implications of Whitebark Pine Loss for Yellowstone Grizzlies

    OpenAIRE

    Willcox, Louisa

    2009-01-01

    Whitebark pine is a foundation species, and barometer of the health of high elevation forests ecosystems in the West. It provides food and cover for numerous wildlife species, including the Clark’s nutcracker, crossbill, grosbeak, red squirrel and chipmunk. Whitebark pine is particularly important in the Greater Yellowstone Ecosystem (GYE), where it provides an essential food source for the imperiled Yellowstone grizzly bear. We will review the current scientific knowledge about the relations...

  10. Insights into the regulation of muscle metabolism and growth in mice and hibernating grizzly bears

    OpenAIRE

    Mugahid (Megahed), Douaa (Doaa)

    2015-01-01

    Mechanotransduction plays an important role in the regulation of muscle growth and metabolic signalling in striated muscle. Muscle disuse reduces mechanical input to the muscle, which results in a loss of muscle mass. Here I describe how titin's mechanically activated kinase domain affects muscle growth and metabolism via p62 and Akt signalling. I also demonstrate how changes in metabolic and growth signalling in hibernating grizzly bear help maintain muscle mass under conditio...

  11. Grizzly bears (Ursus arctos horribilis) and black bears (Ursus americanus) prevent trabecular bone loss during disuse (hibernation).

    Science.gov (United States)

    McGee-Lawrence, Meghan E; Wojda, Samantha J; Barlow, Lindsay N; Drummer, Thomas D; Castillo, Alesha B; Kennedy, Oran; Condon, Keith W; Auger, Janene; Black, Hal L; Nelson, O Lynne; Robbins, Charles T; Donahue, Seth W

    2009-12-01

    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.

  12. Diet and Macronutrient Optimization in Wild Ursids: A Comparison of Grizzly Bears with Sympatric and Allopatric Black Bears.

    Science.gov (United States)

    Costello, Cecily M; Cain, Steven L; Pils, Shannon; Frattaroli, Leslie; Haroldson, Mark A; van Manen, Frank T

    2016-01-01

    When fed ad libitum, ursids can maximize mass gain by selecting mixed diets wherein protein provides 17 ± 4% of digestible energy, relative to carbohydrates or lipids. In the wild, this ability is likely constrained by seasonal food availability, limits of intake rate as body size increases, and competition. By visiting locations of 37 individuals during 274 bear-days, we documented foods consumed by grizzly (Ursus arctos) and black bears (Ursus americanus) in Grand Teton National Park during 2004-2006. Based on published nutritional data, we estimated foods and macronutrients as percentages of daily energy intake. Using principal components and cluster analyses, we identified 14 daily diet types. Only 4 diets, accounting for 21% of days, provided protein levels within the optimal range. Nine diets (75% of days) led to over-consumption of protein, and 1 diet (3% of days) led to under-consumption. Highest protein levels were associated with animal matter (i.e., insects, vertebrates), which accounted for 46-47% of daily energy for both species. As predicted: 1) daily diets dominated by high-energy vertebrates were positively associated with grizzly bears and mean percent protein intake was positively associated with body mass; 2) diets dominated by low-protein fruits were positively associated with smaller-bodied black bears; and 3) mean protein was highest during spring, when high-energy plant foods were scarce, however it was also higher than optimal during summer and fall. Contrary to our prediction: 4) allopatric black bears did not exhibit food selection for high-energy foods similar to grizzly bears. Although optimal gain of body mass was typically constrained, bears usually opted for the energetically superior trade-off of consuming high-energy, high-protein foods. Given protein digestion efficiency similar to obligate carnivores, this choice likely supported mass gain, consistent with studies showing monthly increases in percent body fat among bears in this

  13. Diet and macronutrient optimization in wild ursids: A comparison of grizzly bears with sympatric and allopatric black bears

    Science.gov (United States)

    Costello, Cecily M; Cain, Steven L; Pils, Shannon R; Frattaroli, Leslie; Haroldson, Mark A.; van Manen, Frank T.

    2016-01-01

    When fed ad libitum, ursids can maximize mass gain by selecting mixed diets wherein protein provides 17 ± 4% of digestible energy, relative to carbohydrates or lipids. In the wild, this ability is likely constrained by seasonal food availability, limits of intake rate as body size increases, and competition. By visiting locations of 37 individuals during 274 bear-days, we documented foods consumed by grizzly (Ursus arctos) and black bears (Ursus americanus) in Grand Teton National Park during 2004–2006. Based on published nutritional data, we estimated foods and macronutrients as percentages of daily energy intake. Using principal components and cluster analyses, we identified 14 daily diet types. Only 4 diets, accounting for 21% of days, provided protein levels within the optimal range. Nine diets (75% of days) led to over-consumption of protein, and 1 diet (3% of days) led to under-consumption. Highest protein levels were associated with animal matter (i.e., insects, vertebrates), which accounted for 46–47% of daily energy for both species. As predicted: 1) daily diets dominated by high-energy vertebrates were positively associated with grizzly bears and mean percent protein intake was positively associated with body mass; 2) diets dominated by low-protein fruits were positively associated with smaller-bodied black bears; and 3) mean protein was highest during spring, when high-energy plant foods were scarce, however it was also higher than optimal during summer and fall. Contrary to our prediction: 4) allopatric black bears did not exhibit food selection for high-energy foods similar to grizzly bears. Although optimal gain of body mass was typically constrained, bears usually opted for the energetically superior trade-off of consuming high-energy, high-protein foods. Given protein digestion efficiency similar to obligate carnivores, this choice likely supported mass gain, consistent with studies showing monthly increases in percent body fat among bears in

  14. Diet and Macronutrient Optimization in Wild Ursids: A Comparison of Grizzly Bears with Sympatric and Allopatric Black Bears.

    Directory of Open Access Journals (Sweden)

    Cecily M Costello

    Full Text Available When fed ad libitum, ursids can maximize mass gain by selecting mixed diets wherein protein provides 17 ± 4% of digestible energy, relative to carbohydrates or lipids. In the wild, this ability is likely constrained by seasonal food availability, limits of intake rate as body size increases, and competition. By visiting locations of 37 individuals during 274 bear-days, we documented foods consumed by grizzly (Ursus arctos and black bears (Ursus americanus in Grand Teton National Park during 2004-2006. Based on published nutritional data, we estimated foods and macronutrients as percentages of daily energy intake. Using principal components and cluster analyses, we identified 14 daily diet types. Only 4 diets, accounting for 21% of days, provided protein levels within the optimal range. Nine diets (75% of days led to over-consumption of protein, and 1 diet (3% of days led to under-consumption. Highest protein levels were associated with animal matter (i.e., insects, vertebrates, which accounted for 46-47% of daily energy for both species. As predicted: 1 daily diets dominated by high-energy vertebrates were positively associated with grizzly bears and mean percent protein intake was positively associated with body mass; 2 diets dominated by low-protein fruits were positively associated with smaller-bodied black bears; and 3 mean protein was highest during spring, when high-energy plant foods were scarce, however it was also higher than optimal during summer and fall. Contrary to our prediction: 4 allopatric black bears did not exhibit food selection for high-energy foods similar to grizzly bears. Although optimal gain of body mass was typically constrained, bears usually opted for the energetically superior trade-off of consuming high-energy, high-protein foods. Given protein digestion efficiency similar to obligate carnivores, this choice likely supported mass gain, consistent with studies showing monthly increases in percent body fat among

  15. Implications of a high-energy and low-protein diet on the body composition, fitness, and competitive abilities of black (Ursus americanus) and grizzly (Ursus arctos) bears

    National Research Council Canada - National Science Library

    McLellan, B.N

    2011-01-01

    ...% of the summer diet of both species were fruits that are low in protein. Body composition measurements showed bears loose fat during spring, gained fat during summer, and grizzly bears were leaner than black bears...

  16. Plant consumption by grizzly bears reduces biomagnification of salmon-derived polychlorinated biphenyls, polybrominated diphenyl ethers, and organochlorine pesticides.

    Science.gov (United States)

    Christensen, Jennie R; Yunker, Mark B; MacDuffee, Misty; Ross, Peter S

    2013-04-01

    The present study characterizes the uptake and loss of persistent organic pollutants (POPs) in grizzly bears (Ursus arctos horribilis) by sampling and analyzing their terrestrial and marine foods and fecal material from a remote coastal watershed in British Columbia, Canada. The authors estimate that grizzly bears consume 341 to 1,120 µg of polychlorinated biphenyls (PCBs) and 3.9 to 33 µg of polybrominated diphenyl ethers daily in the fall when they have access to an abundant supply of returning salmon. The authors also estimate that POP elimination by grizzly bears through defecation is very low following salmon consumption (typically 100% for PCBs and organochlorine pesticides). Excretion of individual POPs is largely driven by a combination of fugacity (differences between bear and food concentrations) and the digestibility of the food. The results of the present study are substantiated by a principal components analysis, which also demonstrates a strong role for log KOW in governing the excretion of different POPs in grizzly bears. Collectively, the present study's results reveal that grizzly bears experience a vegetation-associated drawdown of POPs previously acquired through the consumption of salmon, to such an extent that net biomagnification is reduced.

  17. Linking landscape characteristics to local grizzly bear abundance using multiple detection methods in a hierarchical model

    Science.gov (United States)

    Graves, T.A.; Kendall, K.C.; Royle, J. Andrew; Stetz, J.B.; Macleod, A.C.

    2011-01-01

    Few studies link habitat to grizzly bear Ursus arctos abundance and these have not accounted for the variation in detection or spatial autocorrelation. We collected and genotyped bear hair in and around Glacier National Park in northwestern Montana during the summer of 2000. We developed a hierarchical Markov chain Monte Carlo model that extends the existing occupancy and count models by accounting for (1) spatially explicit variables that we hypothesized might influence abundance; (2) separate sub-models of detection probability for two distinct sampling methods (hair traps and rub trees) targeting different segments of the population; (3) covariates to explain variation in each sub-model of detection; (4) a conditional autoregressive term to account for spatial autocorrelation; (5) weights to identify most important variables. Road density and per cent mesic habitat best explained variation in female grizzly bear abundance; spatial autocorrelation was not supported. More female bears were predicted in places with lower road density and with more mesic habitat. Detection rates of females increased with rub tree sampling effort. Road density best explained variation in male grizzly bear abundance and spatial autocorrelation was supported. More male bears were predicted in areas of low road density. Detection rates of males increased with rub tree and hair trap sampling effort and decreased over the sampling period. We provide a new method to (1) incorporate multiple detection methods into hierarchical models of abundance; (2) determine whether spatial autocorrelation should be included in final models. Our results suggest that the influence of landscape variables is consistent between habitat selection and abundance in this system. ?? 2011 The Authors. Animal Conservation ?? 2011 The Zoological Society of London.

  18. Home range size variation in female arctic grizzly bears relative to reproductive status and resource availability.

    Directory of Open Access Journals (Sweden)

    Mark A Edwards

    Full Text Available The area traversed in pursuit of resources defines the size of an animal's home range. For females, the home range is presumed to be a function of forage availability. However, the presence of offspring may also influence home range size due to reduced mobility, increased nutritional need, and behavioral adaptations of mothers to increase offspring survival. Here, we examine the relationship between resource use and variation in home range size for female barren-ground grizzly bears (Ursus arctos of the Mackenzie Delta region in Arctic Canada. We develop methods to test hypotheses of home range size that address selection of cover where cover heterogeneity is low, using generalized linear mixed-effects models and an information-theoretic approach. We found that the reproductive status of female grizzlies affected home range size but individually-based spatial availability of highly selected cover in spring and early summer was a stronger correlate. If these preferred covers in spring and early summer, a period of low resource availability for grizzly bears following den-emergence, were patchy and highly dispersed, females travelled farther regardless of the presence or absence of offspring. Increased movement to preferred covers, however, may result in greater risk to the individual or family.

  19. Home range size variation in female arctic grizzly bears relative to reproductive status and resource availability.

    Science.gov (United States)

    Edwards, Mark A; Derocher, Andrew E; Nagy, John A

    2013-01-01

    The area traversed in pursuit of resources defines the size of an animal's home range. For females, the home range is presumed to be a function of forage availability. However, the presence of offspring may also influence home range size due to reduced mobility, increased nutritional need, and behavioral adaptations of mothers to increase offspring survival. Here, we examine the relationship between resource use and variation in home range size for female barren-ground grizzly bears (Ursus arctos) of the Mackenzie Delta region in Arctic Canada. We develop methods to test hypotheses of home range size that address selection of cover where cover heterogeneity is low, using generalized linear mixed-effects models and an information-theoretic approach. We found that the reproductive status of female grizzlies affected home range size but individually-based spatial availability of highly selected cover in spring and early summer was a stronger correlate. If these preferred covers in spring and early summer, a period of low resource availability for grizzly bears following den-emergence, were patchy and highly dispersed, females travelled farther regardless of the presence or absence of offspring. Increased movement to preferred covers, however, may result in greater risk to the individual or family.

  20. Assessment of pesticide residues in army cutworm moths (Euxoa auxiliaris) from the Greater Yellowstone Ecosystem and their potential consequences to foraging grizzly bears (Ursus arctos horribilis).

    Science.gov (United States)

    Robison, Hillary L; Schwartz, Charles C; Petty, Jim D; Brussard, Peter F

    2006-09-01

    During summer, a grizzly bear (Ursus arctos horribilis) in the Greater Yellowstone Ecosystem (GYE) (USA) can excavate and consume millions of army cutworm moths (Euxoa auxiliaris) (ACMs) that aggregate in high elevation talus. Grizzly bears in the GYE were listed as threatened by the US Fish and Wildlife Service in 1975 and were proposed for delisting in 2005. However, questions remain about key bear foods. For example, ACMs are agricultural pests and concern exists about whether they contain pesticides that could be toxic to bears. Consequently, we investigated whether ACMs contain and transport pesticides to bear foraging sites and, if so, whether these levels could be toxic to bears. In 1999 we collected and analyzed ACMs from six bear foraging sites. ACMs were screened for 32 pesticides with gas chromatography with electron capture detection (GC-ECD). Because gas chromatography with tandem mass spectrometry (GC-MS/MS) can be more sensitive than GC-ECD for certain pesticides, we revisited one site in 2001 and analyzed these ACMs with GC-MS/MS. ACMs contained trace or undetectable levels of pesticides in 1999 and 2001, respectively. Based on chemical levels in ACMs and numbers of ACMs a bear can consume, we calculated the potential of chemicals to reach physiological toxicity. These calculations indicate bears do not consume physiologically toxic levels of pesticides and allay concerns they are at risk from pesticides transported by ACMs. If chemical control of ACMs changes in the future, screening new ACM samples taken from bear foraging sites may be warranted.

  1. Grizzly bear management in Yellowstone National Park: The heart of recovery in the Yellowstone Ecosystem

    Science.gov (United States)

    Schwartz, C.C.; Gunther, K.; McCullough, Dale R.; Kaji, Koichi; Yamanaka, Masami

    2006-01-01

    Grizzly bear (Ursus arctos) management in the Greater Yellowstone Ecosystem (GYE) in the past quarter century has resulted in more than doubling of the population from around 200 to more than 500, expansion of range back into habitats where the bear has extirpated more than a century ago, and a move toward removal from the U.S. Endangered Species list. At the center of this success story are the management programs in Yellowstone National Park (YNP). Regulations that restrict human activity, camping, and food storage, elimination of human food and garbage as attractants, and ranger attendance of roadside bears have all resulted in the population of grizzlies in YNP approaching carrying capacity. Recent studies suggest, however, that YNP alone is too small to support the current population, making management beyond the park boundary important and necessary to the demographics of the population as a whole. Demographic analyses suggest a source-sink dynamic exists within the GYE, with YNP and lands outside the park within the Grizzly Bear Recovery Zone (RZ) representing source habitats, whereas lands beyond the RZ constitute sinks. The source-sink demography in the GYE is indicative of carnivore conservation issues worldwide where many national parks or preserves designed to protect out natural resources are inadequate in size or shape to provide all necessary life history requirements for these wide-ranging species. Additionally, wide-ranging behavior and long-distance dispersal seem inherent to large carnivores, so mortality around the edges is virtually inevitable, and conservation in the GYE is inextricably linked to management regimes not only within YNP, but within the GYE as a whole. We discuss those needs here.

  2. Hibernation-associated changes in persistent organic pollutant (POP) levels and patterns in British Columbia grizzly bears (ursus arctos horribilis).

    Science.gov (United States)

    Christensen, Jennie R; MacDuffee, Misty; Yunker, Mark B; Ross, Peter S

    2007-03-15

    We hypothesized that depleted fat reserves in grizzly bears (Ursus arctos horribilis) following annual hibernation would reveal increases in persistent organic pollutant (POP) concentrations compared to those present in the fall. We obtained fat and hair from British Columbia grizzly bears in early spring 2004 to compare with those collected in fall 2003, with the two tissue types providing contaminant and dietary information, respectively. By correcting for the individual feeding habits of grizzlies using a stable isotope-based approach, we found that polychlorinated biphenyls (sigmaPCBs) increased by 2.21x, polybrominated diphenylethers (sigmaPBDEs) increased by 1.58x, and chlordanes (sigmaCHL) by 1.49x in fat following hibernation. Interestingly, individual POPs elicited a wide range of hibernation-associated concentration effects (e.g., CB-153, 2.25x vs CB-169, 0.00x), resulting in POP pattern convergence in a PCA model of two distinct fall feeding groups (salmon-eating vs non-salmon-eating) into a single spring (post-hibernation) group. Our results suggest that diet dictates contaminant patterns during a feeding phase, while metabolism drives patterns during a fasting phase. This work suggests a duality of POP-associated health risks to hibernating grizzly bears: (1) increased concentrations of some POPs during hibernation; and (2) a potentially prolonged accumulation of water-soluble, highly reactive POP metabolites, since grizzly bears do not excrete during hibernation.

  3. Genetic analysis reveals demographic fragmentation of grizzly bears yielding vulnerably small populations.

    Science.gov (United States)

    Proctor, Michael F; McLellan, Bruce N; Strobeck, Curtis; Barclay, Robert M R

    2005-11-22

    Ecosystem conservation requires the presence of native carnivores, yet in North America, the distributions of many larger carnivores have contracted. Large carnivores live at low densities and require large areas to thrive at the population level. Therefore, if human-dominated landscapes fragment remaining carnivore populations, small and demographically vulnerable populations may result. Grizzly bear range contraction in the conterminous USA has left four fragmented populations, three of which remain along the Canada-USA border. A tenet of grizzly bear conservation is that the viability of these populations requires demographic linkage (i.e. inter-population movement of both sexes) to Canadian bears. Using individual-based genetic analysis, our results suggest this demographic connection has been severed across their entire range in southern Canada by a highway and associated settlements, limiting female and reducing male movement. Two resulting populations are vulnerably small (bear populations may be more threatened than previously thought and that conservation efforts must expand to include international connectivity management. They also demonstrate the ability of genetic analysis to detect gender-specific demographic population fragmentation in recently disturbed systems, a traditionally intractable yet increasingly important ecological measurement worldwide.

  4. Respect for Grizzly Bears: an Aboriginal Approach for Co-existence and Resilience

    Directory of Open Access Journals (Sweden)

    D. Scott. Slocombe

    2009-06-01

    Full Text Available Aboriginal peoples’ respect for grizzly bear (Ursus arctos is widely acknowledged, but rarely explored, in wildlife management discourse in northern Canada. Practices of respect expressed toward bears were observed and grouped into four categories: terminology, stories, reciprocity, and ritual. In the southwest Yukon, practices in all four categories form a coherent qualitative resource management system that may enhance the resilience of the bear-human system as a whole. This system also demonstrates the possibility of a previously unrecognized human role in maintaining productive riparian ecosystems and salmon runs, potentially providing a range of valued social-ecological outcomes. Practices of respect hold promise for new strategies to manage bear-human interactions, but such successful systems may be irreducibly small scale and place based.

  5. Grizzly bear population vital rates and trend in the Northern Continental Divide Ecosystem, Montana

    Science.gov (United States)

    Mace, R.D.; Carney, D.W.; Chilton-Radandt, T.; Courville, S.A.; Haroldson, M.A.; Harris, R.B.; Jonkel, J.; McLellan, B.; Madel, M.; Manley, T.L.; Schwartz, C.C.; Servheen, C.; Stenhouse, G.; Waller, J.S.; Wenum, E.

    2012-01-01

    We estimated grizzly bear (Ursus arctos) population vital rates and trend for the Northern Continental Divide Ecosystem (NCDE), Montana, between 2004 and 2009 by following radio-collared females and observing their fate and reproductive performance. Our estimates of dependent cub and yearling survival were 0.612 (95% CI = 0.300–0.818) and 0.682 (95% CI = 0.258–0.898). Our estimates of subadult and adult female survival were 0.852 (95% CI = 0.628–0.951) and 0.952 (95% CI = 0.892–0.980). From visual observations, we estimated a mean litter size of 2.00 cubs/litter. Accounting for cub mortality prior to the first observations of litters in spring, our adjusted mean litter size was 2.27 cubs/litter. We estimated the probabilities of females transitioning from one reproductive state to another between years. Using the stable state probability of 0.322 (95% CI = 0.262–0.382) for females with cub litters, our adjusted fecundity estimate (mx) was 0.367 (95% CI = 0.273–0.461). Using our derived rates, we estimated that the population grew at a mean annual rate of approximately 3% (λ = 1.0306, 95% CI = 0.928–1.102), and 71.5% of 10,000 Monte Carlo simulations produced estimates of λ > 1.0. Our results indicate an increasing population trend of grizzly bears in the NCDE. Coupled with concurrent studies of population size, we estimate that over 1,000 grizzly bears reside in and adjacent to this recovery area. We suggest that monitoring of population trend and other vital rates using radioed females be continued.

  6. Impacts of rural development on Yellowstone wildlife: linking grizzly bear Ursus arctos demographics with projected residential growth

    Science.gov (United States)

    Schwartz, Charles C.; Gude, Patricia H.; Landenburger, Lisa; Haroldson, Mark A.; Podruzny, Shannon

    2012-01-01

    Exurban development is consuming wildlife habitat within the Greater Yellowstone Ecosystem with potential consequences to the long-term conservation of grizzly bears Ursus arctos. We assessed the impacts of alternative future land-use scenarios by linking an existing regression-based simulation model predicting rural development with a spatially explicit model that predicted bear survival. Using demographic criteria that predict population trajectory, we portioned habitats into either source or sink, and projected the loss of source habitat associated with four different build out (new home construction) scenarios through 2020. Under boom growth, we predicted that 12 km2 of source habitat were converted to sink habitat within the Grizzly Bear Recovery Zone (RZ), 189 km2 were converted within the current distribution of grizzly bears outside of the RZ, and 289 km2 were converted in the area outside the RZ identified as suitable grizzly bear habitat. Our findings showed that extremely low densities of residential development created sink habitats. We suggest that tools, such as those outlined in this article, in addition to zoning and subdivision regulation may prove more practical, and the most effective means of retaining large areas of undeveloped land and conserving grizzly bear source habitat will likely require a landscape-scale approach. We recommend a focus on land conservation efforts that retain open space (easements, purchases and trades) coupled with the implementation of ‘bear community programmes’ on an ecosystem wide basis in an effort to minimize human-bear conflicts, minimize management-related bear mortalities associated with preventable conflicts and to safeguard human communities. Our approach has application to other species and areas, and it has illustrated how spatially explicit demographic models can be combined with models predicting land-use change to help focus conservation priorities.

  7. Macronutrient optimization and seasonal diet mixing in a large omnivore, the grizzly bear: a geometric analysis.

    Directory of Open Access Journals (Sweden)

    Sean C P Coogan

    Full Text Available Nutrient balance is a strong determinant of animal fitness and demography. It is therefore important to understand how the compositions of available foods relate to required balance of nutrients and habitat suitability for animals in the wild. These relationships are, however, complex, particularly for omnivores that often need to compose balanced diets by combining their intake from diverse nutritionally complementary foods. Here we apply geometric models to understand how the nutritional compositions of foods available to an omnivorous member of the order Carnivora, the grizzly bear (Ursus arctos L., relate to optimal macronutrient intake, and assess the seasonal nutritional constraints on the study population in west-central Alberta, Canada. The models examined the proportion of macronutrients that bears could consume by mixing their diet from food available in each season, and assessed the extent to which bears could consume the ratio of protein to non-protein energy previously demonstrated using captive bears to optimize mass gain. We found that non-selective feeding on ungulate carcasses provided a non-optimal macronutrient balance with surplus protein relative to fat and carbohydrate, reflecting adaptation to an omnivorous lifestyle, and that optimization through feeding selectively on different tissues of ungulate carcasses is unlikely. Bears were, however, able to dilute protein intake to an optimal ratio by mixing their otherwise high-protein diet with carbohydrate-rich fruit. Some individual food items were close to optimally balanced in protein to non-protein energy (e.g. Hedysarum alpinum roots, which may help explain their dietary prevalence. Ants may be consumed particularly as a source of lipids. Overall, our analysis showed that most food available to bears in the study area were high in protein relative to lipid or carbohydrate, suggesting the lack of non-protein energy limits the fitness (e.g. body size and reproduction and

  8. Macronutrient optimization and seasonal diet mixing in a large omnivore, the grizzly bear: a geometric analysis.

    Science.gov (United States)

    Coogan, Sean C P; Raubenheimer, David; Stenhouse, Gordon B; Nielsen, Scott E

    2014-01-01

    Nutrient balance is a strong determinant of animal fitness and demography. It is therefore important to understand how the compositions of available foods relate to required balance of nutrients and habitat suitability for animals in the wild. These relationships are, however, complex, particularly for omnivores that often need to compose balanced diets by combining their intake from diverse nutritionally complementary foods. Here we apply geometric models to understand how the nutritional compositions of foods available to an omnivorous member of the order Carnivora, the grizzly bear (Ursus arctos L.), relate to optimal macronutrient intake, and assess the seasonal nutritional constraints on the study population in west-central Alberta, Canada. The models examined the proportion of macronutrients that bears could consume by mixing their diet from food available in each season, and assessed the extent to which bears could consume the ratio of protein to non-protein energy previously demonstrated using captive bears to optimize mass gain. We found that non-selective feeding on ungulate carcasses provided a non-optimal macronutrient balance with surplus protein relative to fat and carbohydrate, reflecting adaptation to an omnivorous lifestyle, and that optimization through feeding selectively on different tissues of ungulate carcasses is unlikely. Bears were, however, able to dilute protein intake to an optimal ratio by mixing their otherwise high-protein diet with carbohydrate-rich fruit. Some individual food items were close to optimally balanced in protein to non-protein energy (e.g. Hedysarum alpinum roots), which may help explain their dietary prevalence. Ants may be consumed particularly as a source of lipids. Overall, our analysis showed that most food available to bears in the study area were high in protein relative to lipid or carbohydrate, suggesting the lack of non-protein energy limits the fitness (e.g. body size and reproduction) and population density

  9. The effects of automated scatter feeders on captive grizzly bear activity budgets.

    Science.gov (United States)

    Andrews, Nathan L P; Ha, James C

    2014-01-01

    Although captive bears are popular zoo attractions, they are known to exhibit high levels of repetitive behaviors (RBs). These behaviors have also made them particularly popular subjects for welfare research. To date, most research on ursid welfare has focused on various feeding methods that seek to increase time spent searching for, extracting, or consuming food. Prior research indicates an average of a 50% reduction in RBs when attempts are successful and, roughly, a 50% success rate across studies. This research focused on decreasing time spent in an RB while increasing the time spent active by increasing time spent searching for, extracting, and consuming food. The utility of timed, automated scatter feeders was examined for use with captive grizzly bears (Ursis arctos horribilis). Findings include a significant decrease in time spent in RB and a significant increase in time spent active while the feeders were in use. Further, the bears exhibited a wider range of behaviors and a greater use of their enclosure.

  10. Grizzly bear monitoring by the Heiltsuk people as a crucible for First Nation conservation practice

    Directory of Open Access Journals (Sweden)

    William G. Housty

    2014-06-01

    Full Text Available Guided by deeply held cultural values, First Nations in Canada are rapidly regaining legal authority to manage natural resources. We present a research collaboration among academics, tribal government, provincial and federal government, resource managers, conservation practitioners, and community leaders supporting First Nation resource authority and stewardship. First, we present results from a molecular genetics study of grizzly bears inhabiting an important conservation area within the territory of the Heiltsuk First Nation in coastal British Columbia. Noninvasive hair sampling occurred between 2006 and 2009 in the Koeye watershed, a stronghold for grizzly bears, salmon, and Heiltsuk people. Molecular demographic analyses revealed a regionally significant population of bears, which congregate at the Koeye each salmon-spawning season. There was a minimum of 57 individual bears detected during the study period. Results also pointed to a larger than expected source geography for salmon-feeding bears in the study area (> 1000 km², as well as early evidence of a declining trend in the bear population potentially explained by declining salmon numbers. Second, we demonstrate and discuss the power of integrating scientific research with a culturally appropriate research agenda developed by indigenous people. Guided explicitly by principles from Gvi'ilas or customary law, this research methodology is coupled with Heiltsuk culture, enabling results of applied conservation science to involve and resonate with tribal leadership in ways that have eluded previous scientific endeavors. In this context, we discuss the effectiveness of research partnerships that, from the outset, create both scientific programs and integrated communities of action that can implement change. We argue that indigenous resource management requires collaborative approaches like ours, in which science-based management is embedded within a socially and culturally appropriate

  11. Carnivore re-colonisation: Reality, possibility and a non-equilibrium century for grizzly bears in the southern Yellowstone ecosystem

    Science.gov (United States)

    Pyare, Sanjay; Cain, S.; Moody, D.; Schwartz, C.; Berger, J.

    2004-01-01

    Most large native carnivores have experienced range contractions due to conflicts with humans, although neither rates of spatial collapse nor expansion have been well characterised. In North America, the grizzly bear (Ursus arctos) once ranged from Mexico northward to Alaska, however its range in the continental USA has been reduced by 95-98%. Under the U. S. Endangered Species Act, the Yellowstone grizzly bear population has re-colonised habitats outside Yellowstone National Park. We analysed historical and current records, including data on radio-collared bears, (1) to evaluate changes in grizzly bear distribution in the southern Greater Yellowstone Ecosystem (GYE) over a 100-year period, (2) to utilise historical rates of re-colonisation to project future expansion trends and (3) to evaluate the reality of future expansion based on human limitations and land use. Analysis of distribution in 20-year increments reflects range reduction from south to north (1900-1940) and expansion to the south (1940-2000). Expansion was exponential and the area occupied by grizzly bears doubled approximately every 20 years. A complementary analysis of bear occurrence in Grand Teton National Park also suggests an unprecedented period of rapid expansion during the last 20-30 years. The grizzly bear population currently has re-occupied about 50% of the southern GYE. Based on assumptions of continued protection and ecological stasis, our model suggests total occupancy in 25 years. Alternatively, extrapolation of linear expansion rates from the period prior to protection suggests total occupancy could take > 100 years. Analyses of historical trends can be useful as a restoration tool because they enable a framework and timeline to be constructed to pre-emptively address the social challenges affecting future carnivore recovery. ?? 2004 The Zoological Society of London.

  12. Detecting grizzly bear use of ungulate carcasses using global positioning system telemetry and activity data.

    Science.gov (United States)

    Ebinger, Michael R; Haroldson, Mark A; van Manen, Frank T; Costello, Cecily M; Bjornlie, Daniel D; Thompson, Daniel J; Gunther, Kerry A; Fortin, Jennifer K; Teisberg, Justin E; Pils, Shannon R; White, P J; Cain, Steven L; Cross, Paul C

    2016-07-01

    Global positioning system (GPS) wildlife collars have revolutionized wildlife research. Studies of predation by free-ranging carnivores have particularly benefited from the application of location clustering algorithms to determine when and where predation events occur. These studies have changed our understanding of large carnivore behavior, but the gains have concentrated on obligate carnivores. Facultative carnivores, such as grizzly/brown bears (Ursus arctos), exhibit a variety of behaviors that can lead to the formation of GPS clusters. We combined clustering techniques with field site investigations of grizzly bear GPS locations (n = 732 site investigations; 2004-2011) to produce 174 GPS clusters where documented behavior was partitioned into five classes (large-biomass carcass, small-biomass carcass, old carcass, non-carcass activity, and resting). We used multinomial logistic regression to predict the probability of clusters belonging to each class. Two cross-validation methods-leaving out individual clusters, or leaving out individual bears-showed that correct prediction of bear visitation to large-biomass carcasses was 78-88 %, whereas the false-positive rate was 18-24 %. As a case study, we applied our predictive model to a GPS data set of 266 bear-years in the Greater Yellowstone Ecosystem (2002-2011) and examined trends in carcass visitation during fall hyperphagia (September-October). We identified 1997 spatial GPS clusters, of which 347 were predicted to be large-biomass carcasses. We used the clustered data to develop a carcass visitation index, which varied annually, but more than doubled during the study period. Our study demonstrates the effectiveness and utility of identifying GPS clusters associated with carcass visitation by a facultative carnivore.

  13. Grizzly bears exhibit augmented insulin sensitivity while obese prior to a reversible insulin resistance during hibernation.

    Science.gov (United States)

    Nelson, O Lynne; Jansen, Heiko T; Galbreath, Elizabeth; Morgenstern, Kurt; Gehring, Jamie Lauren; Rigano, Kimberly Scott; Lee, Jae; Gong, Jianhua; Shaywitz, Adam J; Vella, Chantal A; Robbins, Charles T; Corbit, Kevin C

    2014-08-01

    The confluence of obesity and diabetes as a worldwide epidemic necessitates the discovery of new therapies. Success in this endeavor requires translatable preclinical studies, which traditionally employ rodent models. As an alternative approach, we explored hibernation where obesity is a natural adaptation to survive months of fasting. Here we report that grizzly bears exhibit seasonal tripartite insulin responsiveness such that obese animals augment insulin sensitivity but only weeks later enter hibernation-specific insulin resistance (IR) and subsequently reinitiate responsiveness upon awakening. Preparation for hibernation is characterized by adiposity coupled to increased insulin sensitivity via modified PTEN/AKT signaling specifically in adipose tissue, suggesting a state of "healthy" obesity analogous to humans with PTEN haploinsufficiency. Collectively, we show that bears reversibly cope with homeostatic perturbations considered detrimental to humans and describe a mechanism whereby IR functions not as a late-stage metabolic adaptation to obesity, but rather a gatekeeper of the fed-fasting transition.

  14. Detecting grizzly bear use of ungulate carcasses using global positioning system telemetry and activity data

    Science.gov (United States)

    Ebinger, Michael R.; Haroldson, Mark A.; van Manen, Frank T.; Costello, Cecily M; Bjornlie, Daniel D; Thompson, Daniel J.; Gunther, Kerry A.; Fortin, Jennifer K.; Teisberg, Justin E.; Pils, Shannon R; White, P J; Cain, Steven L; Cross, Paul C.

    2016-01-01

    Global positioning system (GPS) wildlife collars have revolutionized wildlife research. Studies of predation by free-ranging carnivores have particularly benefited from the application of location clustering algorithms to determine when and where predation events occur. These studies have changed our understanding of large carnivore behavior, but the gains have concentrated on obligate carnivores. Facultative carnivores, such as grizzly/brown bears (Ursus arctos), exhibit a variety of behaviors that can lead to the formation of GPS clusters. We combined clustering techniques with field site investigations of grizzly bear GPS locations (n = 732 site investigations; 2004–2011) to produce 174 GPS clusters where documented behavior was partitioned into five classes (large-biomass carcass, small-biomass carcass, old carcass, non-carcass activity, and resting). We used multinomial logistic regression to predict the probability of clusters belonging to each class. Two cross-validation methods—leaving out individual clusters, or leaving out individual bears—showed that correct prediction of bear visitation to large-biomass carcasses was 78–88%, whereas the false-positive rate was 18–24%. As a case study, we applied our predictive model to a GPS data set of 266 bear-years in the Greater Yellowstone Ecosystem (2002–2011) and examined trends in carcass visitation during fall hyperphagia (September–October). We identified 1997 spatial GPS clusters, of which 347 were predicted to be large-biomass carcasses. We used the clustered data to develop a carcass visitation index, which varied annually, but more than doubled during the study period. Our study demonstrates the effectiveness and utility of identifying GPS clusters associated with carcass visitation by a facultative carnivore.

  15. Multiple data sources improve DNA-based mark-recapture population estimates of grizzly bears.

    Science.gov (United States)

    Boulanger, John; Kendall, Katherine C; Stetz, Jeffrey B; Roon, David A; Waits, Lisette P; Paetkau, David

    2008-04-01

    A fundamental challenge to estimating population size with mark-recapture methods is heterogeneous capture probabilities and subsequent bias of population estimates. Confronting this problem usually requires substantial sampling effort that can be difficult to achieve for some species, such as carnivores. We developed a methodology that uses two data sources to deal with heterogeneity and applied this to DNA mark-recapture data from grizzly bears (Ursus arctos). We improved population estimates by incorporating additional DNA "captures" of grizzly bears obtained by collecting hair from unbaited bear rub trees concurrently with baited, grid-based, hair snag sampling. We consider a Lincoln-Petersen estimator with hair snag captures as the initial session and rub tree captures as the recapture session and develop an estimator in program MARK that treats hair snag and rub tree samples as successive sessions. Using empirical data from a large-scale project in the greater Glacier National Park, Montana, USA, area and simulation modeling we evaluate these methods and compare the results to hair-snag-only estimates. Empirical results indicate that, compared with hair-snag-only data, the joint hair-snag-rub-tree methods produce similar but more precise estimates if capture and recapture rates are reasonably high for both methods. Simulation results suggest that estimators are potentially affected by correlation of capture probabilities between sample types in the presence of heterogeneity. Overall, closed population Huggins-Pledger estimators showed the highest precision and were most robust to sparse data, heterogeneity, and capture probability correlation among sampling types. Results also indicate that these estimators can be used when a segment of the population has zero capture probability for one of the methods. We propose that this general methodology may be useful for other species in which mark-recapture data are available from multiple sources.

  16. Human perspectives and conservation of grizzly bears in Banff National Park, Canada.

    Science.gov (United States)

    Chamberlain, Emily C; Rutherford, Murray B; Gibeau, Michael L

    2012-06-01

    Some conservation initiatives provoke intense conflict among stakeholders. The need for action, the nature of the conservation measures, and the effects of these measures on human interests may be disputed. Tools are needed to depolarize such situations, foster understanding of the perspectives of people involved, and find common ground. We used Q methodology to explore stakeholders' perspectives on conservation and management of grizzly bears (Ursus arctos horribilis) in Banff National Park and the Bow River watershed of Alberta, Canada. Twenty-nine stakeholders participated in the study, including local residents, scientists, agency employees, and representatives of nongovernmental conservation organizations and other interest groups. Participants rank ordered a set of statements to express their opinions on the problems of grizzly bear management (I-IV) and a second set of statements on possible solutions to the problems (A-C). Factor analysis revealed that participants held 4 distinct views of the problems: individuals associated with factor I emphasized deficiencies in goals and plans; those associated with factor II believed that problems had been exaggerated; those associated with factor III blamed institutional flaws such as disjointed management and inadequate resources; and individuals associated with factor IV blamed politicized decision making. There were 3 distinct views about the best solutions to the problems: individuals associated with factor A called for increased conservation efforts; those associated with factor B wanted reforms in decision-making processes; and individuals associated with factor C supported active landscape management. We connected people's definitions of the problem with their preferred solutions to form 5 overall problem narratives espoused by groups in the study: the problem is deficient goals and plans, the solution is to prioritize conservation efforts (planning-oriented conservation advocates); the problem is flawed

  17. Geographic pattern of serum antibody prevalence for Brucella spp. in caribou, grizzly bears, and wolves from Alaska, 1975-1998.

    Science.gov (United States)

    Zarnke, Randall L; Ver Hoef, Jay M; DeLong, Robert A

    2006-07-01

    Blood samples were collected from 2,635 caribou (Rangifer tarandus), 1,238 grizzly bears (Ursus arctos), and 930 wolves (Canis lupus) from throughout mainland Alaska during 1975-98. Sera were tested for evidence of exposure to Brucella spp. Serum antibody prevalences were highest in the northwestern region of the state. In any specific area, antibody prevalences for caribou and wolves were of a similar magnitude, whereas antibody prevalence for bears in these same areas were two to three times higher.

  18. Effect of season and high ambient temperature on activity levels and patterns of grizzly bears (Ursus arctos.

    Directory of Open Access Journals (Sweden)

    Michelle L McLellan

    Full Text Available Understanding factors that influence daily and annual activity patterns of a species provides insights to challenges facing individuals, particularly when climate shifts, and thus is important in conservation. Using GPS collars with dual-axis motion sensors that recorded the number of switches every 5 minutes we tested the hypotheses: 1. Grizzly bears (Ursus arctos increase daily activity levels and active bout lengths when they forage on berries, the major high-energy food in this ecosystem, and 2. Grizzly bears become less active and more nocturnal when ambient temperature exceeds 20°C. We found support for hypothesis 1 with both male and female bears being active from 0.7 to 2.8 h longer in the berry season than in other seasons. Our prediction under hypothesis 2 was not supported. When bears foraged on berries on a dry, open mountainside, there was no relationship between daily maximum temperature (which varied from 20.4 to 40.1°C and the total amount of time bears were active, and no difference in activity levels during day or night between warm (20.4-27.3°C and hot (27.9-40.1°C days. Our results highlight the strong influence that food acquisition has on activity levels and patterns of grizzly bears and is a challenge to the heat dissipation limitation theory.

  19. Effect of season and high ambient temperature on activity levels and patterns of grizzly bears (Ursus arctos).

    Science.gov (United States)

    McLellan, Michelle L; McLellan, Bruce N

    2015-01-01

    Understanding factors that influence daily and annual activity patterns of a species provides insights to challenges facing individuals, particularly when climate shifts, and thus is important in conservation. Using GPS collars with dual-axis motion sensors that recorded the number of switches every 5 minutes we tested the hypotheses: 1. Grizzly bears (Ursus arctos) increase daily activity levels and active bout lengths when they forage on berries, the major high-energy food in this ecosystem, and 2. Grizzly bears become less active and more nocturnal when ambient temperature exceeds 20°C. We found support for hypothesis 1 with both male and female bears being active from 0.7 to 2.8 h longer in the berry season than in other seasons. Our prediction under hypothesis 2 was not supported. When bears foraged on berries on a dry, open mountainside, there was no relationship between daily maximum temperature (which varied from 20.4 to 40.1°C) and the total amount of time bears were active, and no difference in activity levels during day or night between warm (20.4-27.3°C) and hot (27.9-40.1°C) days. Our results highlight the strong influence that food acquisition has on activity levels and patterns of grizzly bears and is a challenge to the heat dissipation limitation theory.

  20. Cooperative Recovery Initiative (2016) Grizzly Bear Aware: Conflict Resolution and Habitat Restoration in the Centennial Valley and Southwest Montana Interim Report

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The project will take a three pronged approach to implement conservation actions that prevent or reduce Grizzly Bear human conflicts, enhance habitats and improve...

  1. Fast carnivores and slow herbivores: differential foraging strategies among grizzly bears in the Canadian Arctic.

    Science.gov (United States)

    Edwards, Mark A; Derocher, Andrew E; Hobson, Keith A; Branigan, Marsha; Nagy, John A

    2011-04-01

    Categorizing animal populations by diet can mask important intrapopulation variation, which is crucial to understanding a species' trophic niche width. To test hypotheses related to intrapopulation variation in foraging or the presence of diet specialization, we conducted stable isotope analysis (δ(13)C, δ(15)N) on hair and claw samples from 51 grizzly bears (Ursus arctos) collected from 2003 to 2006 in the Mackenzie Delta region of the Canadian Arctic. We examined within-population differences in the foraging patterns of males and females and the relationship between trophic position (derived from δ(15)N measurements) and individual movement. The range of δ(15)N values in hair and claw (2.0-11.0‰) suggested a wide niche width and cluster analyses indicated the presence of three foraging groups within the population, ranging from near-complete herbivory to near-complete carnivory. We found no linear relationship between home range size and trophic position when the data were continuous or when grouped by foraging behavior. However, the movement rate of females increased linearly with trophic position. We used multisource dual-isotope mixing models to determine the relative contributions of seven prey sources within each foraging group for both males and females. The mean bear dietary endpoint across all foraging groups for each sex fell toward the center of the mixing polygon, which suggested relatively well-mixed diets. The primary dietary difference across foraging groups was the proportional contribution of herbaceous foods, which decreased for both males and females from 42-76 to 0-27% and 62-81 to 0-44%, respectively. Grizzlies of the Mackenzie Delta live in extremely harsh conditions and identifying within-population diet specialization has improved our understanding of varying habitat requirements within the population.

  2. Using grizzly bears to assess harvest-ecosystem tradeoffs in salmon fisheries.

    Science.gov (United States)

    Levi, Taal; Darimont, Chris T; Macduffee, Misty; Mangel, Marc; Paquet, Paul; Wilmers, Christopher C

    2012-01-01

    Implementation of ecosystem-based fisheries management (EBFM) requires a clear conceptual and quantitative framework for assessing how different harvest options can modify benefits to ecosystem and human beneficiaries. We address this social-ecological need for Pacific salmon fisheries, which are economically valuable but intercept much of the annual pulse of nutrient subsidies that salmon provide to terrestrial and aquatic food webs. We used grizzly bears, vectors of salmon nutrients and animals with densities strongly coupled to salmon abundance, as surrogates for "salmon ecosystem" function. Combining salmon biomass and stock-recruitment data with stable isotope analysis, we assess potential tradeoffs between fishery yields and bear population densities for six sockeye salmon stocks in Bristol Bay, Alaska, and British Columbia (BC), Canada. For the coastal stocks, we find that both bear densities and fishery yields would increase substantially if ecosystem allocations of salmon increase from currently applied lower to upper goals and beyond. This aligning of benefits comes at a potential cost, however, with the possibility of forgoing harvests in low productivity years. In contrast, we detect acute tradeoffs between bear densities and fishery yields in interior stocks within the Fraser River, BC, where biomass from other salmon species is low. There, increasing salmon allocations to ecosystems would benefit threatened bear populations at the cost of reduced long-term yields. To resolve this conflict, we propose an EBFM goal that values fisheries and bears (and by extension, the ecosystem) equally. At such targets, ecosystem benefits are unexpectedly large compared with losses in fishery yields. To explore other management options, we generate tradeoff curves that provide stock-specific accounting of the expected loss to fishers and gain to bears as more salmon escape the fishery. Our approach, modified to suit multiple scenarios, provides a generalizable method

  3. Using grizzly bears to assess harvest-ecosystem tradeoffs in salmon fisheries.

    Directory of Open Access Journals (Sweden)

    Taal Levi

    Full Text Available Implementation of ecosystem-based fisheries management (EBFM requires a clear conceptual and quantitative framework for assessing how different harvest options can modify benefits to ecosystem and human beneficiaries. We address this social-ecological need for Pacific salmon fisheries, which are economically valuable but intercept much of the annual pulse of nutrient subsidies that salmon provide to terrestrial and aquatic food webs. We used grizzly bears, vectors of salmon nutrients and animals with densities strongly coupled to salmon abundance, as surrogates for "salmon ecosystem" function. Combining salmon biomass and stock-recruitment data with stable isotope analysis, we assess potential tradeoffs between fishery yields and bear population densities for six sockeye salmon stocks in Bristol Bay, Alaska, and British Columbia (BC, Canada. For the coastal stocks, we find that both bear densities and fishery yields would increase substantially if ecosystem allocations of salmon increase from currently applied lower to upper goals and beyond. This aligning of benefits comes at a potential cost, however, with the possibility of forgoing harvests in low productivity years. In contrast, we detect acute tradeoffs between bear densities and fishery yields in interior stocks within the Fraser River, BC, where biomass from other salmon species is low. There, increasing salmon allocations to ecosystems would benefit threatened bear populations at the cost of reduced long-term yields. To resolve this conflict, we propose an EBFM goal that values fisheries and bears (and by extension, the ecosystem equally. At such targets, ecosystem benefits are unexpectedly large compared with losses in fishery yields. To explore other management options, we generate tradeoff curves that provide stock-specific accounting of the expected loss to fishers and gain to bears as more salmon escape the fishery. Our approach, modified to suit multiple scenarios, provides a

  4. Influence of whitebark pine decline on fall habitat use and movements of grizzly bears in the Greater Yellowstone Ecosystem.

    Science.gov (United States)

    Costello, Cecily M; van Manen, Frank T; Haroldson, Mark A; Ebinger, Michael R; Cain, Steven L; Gunther, Kerry A; Bjornlie, Daniel D

    2014-05-01

    When abundant, seeds of the high-elevation whitebark pine (WBP; Pinus albicaulis) are an important fall food for grizzly bears (Ursus arctos) in the Greater Yellowstone Ecosystem. Rates of bear mortality and bear/human conflicts have been inversely associated with WBP productivity. Recently, mountain pine beetles (Dendroctonus ponderosae) have killed many cone-producing WBP trees. We used fall (15 August-30 September) Global Positioning System locations from 89 bear years to investigate temporal changes in habitat use and movements during 2000-2011. We calculated Manly-Chesson (MC) indices for selectivity of WBP habitat and secure habitat (≥500 m from roads and human developments), determined dates of WBP use, and documented net daily movement distances and activity radii. To evaluate temporal trends, we used regression, model selection, and candidate model sets consisting of annual WBP production, sex, and year. One-third of sampled grizzly bears had fall ranges with little or no mapped WBP habitat. Most other bears (72%) had a MC index above 0.5, indicating selection for WBP habitats. From 2000 to 2011, mean MC index decreased and median date of WBP use shifted about 1 week later. We detected no trends in movement indices over time. Outside of national parks, there was no correlation between the MC indices for WBP habitat and secure habitat, and most bears (78%) selected for secure habitat. Nonetheless, mean MC index for secure habitat decreased over the study period during years of good WBP productivity. The wide diet breadth and foraging plasticity of grizzly bears likely allowed them to adjust to declining WBP. Bears reduced use of WBP stands without increasing movement rates, suggesting they obtained alternative fall foods within their local surroundings. However, the reduction in mortality risk historically associated with use of secure, high-elevation WBP habitat may be diminishing for bears residing in multiple-use areas.

  5. Grizzly bear predation links the loss of native trout to the demography of migratory elk in Yellowstone

    Science.gov (United States)

    Middleton, Arthur D.; Morrison, Thomas A.; Fortin, Jennifer K.; Robbins, Charles T.; Proffitt, Kelly M.; White, P.J.; McWhirter, Douglas E.; Koel, Todd M.; Brimeyer, Douglas G.; Fairbanks, W. Sue; Kauffman, Matthew J.

    2013-01-01

    The loss of aquatic subsidies such as spawning salmonids is known to threaten a number of terrestrial predators, but the effects on alternative prey species are poorly understood. At the heart of the Greater Yellowstone ecosystem, an invasion of lake trout has driven a dramatic decline of native cutthroat trout that migrate up the shallow tributaries of Yellowstone Lake to spawn each spring. We explore whether this decline has amplified the effect of a generalist consumer, the grizzly bear, on populations of migratory elk that summer inside Yellowstone National Park (YNP). Recent studies of bear diets and elk populations indicate that the decline in cutthroat trout has contributed to increased predation by grizzly bears on the calves of migratory elk. Additionally, a demographic model that incorporates the increase in predation suggests that the magnitude of this diet shift has been sufficient to reduce elk calf recruitment (4–16%) and population growth (2–11%). The disruption of this aquatic–terrestrial linkage could permanently alter native species interactions in YNP. Although many recent ecological changes in YNP have been attributed to the recovery of large carnivores—particularly wolves—our work highlights a growing role of human impacts on the foraging behaviour of grizzly bears.

  6. Grizzly bear predation links the loss of native trout to the demography of migratory elk in Yellowstone.

    Science.gov (United States)

    Middleton, Arthur D; Morrison, Thomas A; Fortin, Jennifer K; Robbins, Charles T; Proffitt, Kelly M; White, P J; McWhirter, Douglas E; Koel, Todd M; Brimeyer, Douglas G; Fairbanks, W Sue; Kauffman, Matthew J

    2013-07-07

    The loss of aquatic subsidies such as spawning salmonids is known to threaten a number of terrestrial predators, but the effects on alternative prey species are poorly understood. At the heart of the Greater Yellowstone ecosystem, an invasion of lake trout has driven a dramatic decline of native cutthroat trout that migrate up the shallow tributaries of Yellowstone Lake to spawn each spring. We explore whether this decline has amplified the effect of a generalist consumer, the grizzly bear, on populations of migratory elk that summer inside Yellowstone National Park (YNP). Recent studies of bear diets and elk populations indicate that the decline in cutthroat trout has contributed to increased predation by grizzly bears on the calves of migratory elk. Additionally, a demographic model that incorporates the increase in predation suggests that the magnitude of this diet shift has been sufficient to reduce elk calf recruitment (4-16%) and population growth (2-11%). The disruption of this aquatic-terrestrial linkage could permanently alter native species interactions in YNP. Although many recent ecological changes in YNP have been attributed to the recovery of large carnivores--particularly wolves--our work highlights a growing role of human impacts on the foraging behaviour of grizzly bears.

  7. Evaluation of rules to distinguish unique female grizzly bears with cubs in Yellowstone

    Science.gov (United States)

    Schwartz, C.C.; Haroldson, M.A.; Cherry, S.; Keating, K.A.

    2008-01-01

    The United States Fish and Wildlife Service uses counts of unduplicated female grizzly bears (Ursus arctos) with cubs-of-the-year to establish limits of sustainable mortality in the Greater Yellowstone Ecosystem, USA. Sightings are dustered into observations of unique bears based on an empirically derived rule set. The method has never been tested or verified. To evaluate the rule set, we used data from radiocollared females obtained during 1975-2004 to simulate populations under varying densities, distributions, and sighting frequencies. We tested individual rules and rule-set performance, using custom software to apply the rule-set and duster sightings. Results indicated most rules were violated to some degree, and rule-based dustering consistently underestimated the minimum number of females and total population size derived from a nonparametric estimator (Chao2). We conclude that the current rule set returns conservative estimates, but with minor improvements, counts of unduplicated females-with-cubs can serve as a reasonable index of population size useful for establishing annual mortality limits. For the Yellowstone population, the index is more practical and cost-effective than capture-mark-recapture using either DNA hair snagging or aerial surveys with radiomarked bears. The method has useful application in other ecosystems, but we recommend rules used to distinguish unique females be adapted to local conditions and tested.

  8. Diet and environment shape fecal bacterial microbiota composition and enteric pathogen load of grizzly bears.

    Directory of Open Access Journals (Sweden)

    Clarissa Schwab

    Full Text Available BACKGROUND: Diet and environment impact the composition of mammalian intestinal microbiota; dietary or health disturbances trigger alterations in intestinal microbiota composition and render the host susceptible to enteric pathogens. To date no long term monitoring data exist on the fecal microbiota and pathogen load of carnivores either in natural environments or in captivity. This study investigates fecal microbiota composition and the presence of pathogenic Escherichia coli and toxigenic clostridia in wild and captive grizzly bears (Ursus arctos and relates these to food resources consumed by bears. METHODOLOGY/PRINCIPAL FINDINGS: Feces were obtained from animals of two wild populations and from two captive animals during an active bear season. Wild animals consumed a diverse diet composed of plant material, animal prey and insects. Captive animals were fed a regular granulated diet with a supplement of fruits and vegetables. Bacterial populations were analyzed using quantitative PCR. Fecal microbiota composition fluctuated in wild and in captive animals. The abundance of Clostridium clusters I and XI, and of C. perfringens correlated to regular diet protein intake. Enteroaggregative E. coli were consistently present in all populations. The C. sordellii phospholipase C was identified in three samples of wild animals and for the first time in Ursids. CONCLUSION: This is the first longitudinal study monitoring the fecal microbiota of wild carnivores and comparing it to that of captive individuals of the same species. Location and diet affected fecal bacterial populations as well as the presence of enteric pathogens.

  9. The influence of sulfur and hair growth on stable isotope diet estimates for grizzly bears.

    Science.gov (United States)

    Mowat, Garth; Curtis, P Jeff; Lafferty, Diana J R

    2017-01-01

    Stable isotope ratios of grizzly bear (Ursus arctos) guard hair collected from bears on the lower Stikine River, British Columbia (BC) were analyzed to: 1) test whether measuring δ34S values improved the precision of the salmon (Oncorhynchus spp.) diet fraction estimate relative to δ15N as is conventionally done, 2) investigate whether measuring δ34S values improves the separation of diet contributions of moose (Alces alces), marmot (Marmota caligata), and mountain goat (Oreamnos americanus) and, 3) examine the relationship between collection date and length of hair and stable isotope values. Variation in isotope signatures among hair samples from the same bear and year were not trivial. The addition of δ34S values to mixing models used to estimate diet fractions generated small improvement in the precision of salmon and terrestrial prey diet fractions. Although the δ34S value for salmon is precise and appears general among species and areas, sulfur ratios were strongly correlated with nitrogen ratios and therefore added little new information to the mixing model regarding the consumption of salmon. Mean δ34S values for the three terrestrial herbivores of interest were similar and imprecise, so these data also added little new information to the mixing model. The addition of sulfur data did confirm that at least some bears in this system ate marmots during summer and fall. We show that there are bears with short hair that assimilate >20% salmon in their diet and bears with longer hair that eat no salmon living within a few kilometers of one another in a coastal ecosystem. Grizzly bears are thought to re-grow hair between June and October however our analysis of sectioned hair suggested at least some hairs begin growing in July or August, not June and, that hair of wild bears may grow faster than observed in captive bears. Our hair samples may have been from the year of sampling or the previous year because samples were collected in summer when bears were

  10. Re-evaluation of Yellowstone grizzly bear population dynamics not supported by empirical data: response to Doak & Cutler

    Science.gov (United States)

    van Manen, Frank T.; Ebinger, Michael R.; Haroldson, Mark A.; Harris, Richard B.; Higgs, Megan D.; Cherry, Steve; White, Gary C.; Schwartz, Charles C.

    2014-01-01

    Doak and Cutler critiqued methods used by the Interagency Grizzly Bear Study Team (IGBST) to estimate grizzly bear population size and trend in the Greater Yellowstone Ecosystem. Here, we focus on the premise, implementation, and interpretation of simulations they used to support their arguments. They argued that population increases documented by IGBST based on females with cubs-of-the-year were an artifact of increased search effort. However, we demonstrate their simulations were neither reflective of the true observation process nor did their results provide statistical support for their conclusion. They further argued that survival and reproductive senescence should be incorporated into population projections, but we demonstrate their choice of extreme mortality risk beyond age 20 and incompatible baseline fecundity led to erroneous conclusions. The conclusions of Doak and Cutler are unsubstantiated when placed within the context of a thorough understanding of the data, study system, and previous research findings and publications.

  11. Despotism and risk of infanticide influence grizzly bear den-site selection.

    Directory of Open Access Journals (Sweden)

    Nathan S Libal

    Full Text Available Given documented social dominance and intraspecific predation in bear populations, the ideal despotic distribution model and sex hypothesis of sexual segregation predict adult female grizzly bears (Ursus arctos will avoid areas occupied by adult males to reduce risk of infanticide. Under ideal despotic distribution, juveniles should similarly avoid adult males to reduce predation risk. Den-site selection and use is an important component of grizzly bear ecology and may be influenced by multiple factors, including risk from conspecifics. To test the role of predation risk and the sex hypothesis of sexual segregation, we compared adult female (n = 142, adult male (n = 36, and juvenile (n = 35 den locations in Denali National Park and Preserve, Alaska, USA. We measured elevation, aspect, slope, and dominant land cover for each den site, and used maximum entropy modeling to determine which variables best predicted den sites. We identified the global model as the best-fitting model for adult female (area under curve (AUC = 0.926 and elevation as the best predictive variable for adult male (AUC = 0.880 den sites. The model containing land cover and elevation best-predicted juvenile (AUC = 0.841 den sites. Adult females spatially segregated from adult males, with dens characterized by higher elevations (mean= 1,412 m, SE = 52 and steeper slopes (mean = 21.9°, SE = 1.1 than adult male (elevation: mean = 1,209 m, SE = 76; slope: mean = 15.6°, SE = 1.9 den sites. Juveniles used a broad range of landscape attributes but did not avoid adult male denning areas. Observed spatial segregation by adult females supports the sex hypothesis of sexual segregation and we suggest is a mechanism to reduce risk of infanticide. Den site selection of adult males is likely related to distribution of food resources during spring.

  12. Despotism and risk of infanticide influence grizzly bear den-site selection.

    Science.gov (United States)

    Libal, Nathan S; Belant, Jerrold L; Leopold, Bruce D; Wang, Guiming; Owen, Patricia A

    2011-01-01

    Given documented social dominance and intraspecific predation in bear populations, the ideal despotic distribution model and sex hypothesis of sexual segregation predict adult female grizzly bears (Ursus arctos) will avoid areas occupied by adult males to reduce risk of infanticide. Under ideal despotic distribution, juveniles should similarly avoid adult males to reduce predation risk. Den-site selection and use is an important component of grizzly bear ecology and may be influenced by multiple factors, including risk from conspecifics. To test the role of predation risk and the sex hypothesis of sexual segregation, we compared adult female (n = 142), adult male (n = 36), and juvenile (n = 35) den locations in Denali National Park and Preserve, Alaska, USA. We measured elevation, aspect, slope, and dominant land cover for each den site, and used maximum entropy modeling to determine which variables best predicted den sites. We identified the global model as the best-fitting model for adult female (area under curve (AUC) = 0.926) and elevation as the best predictive variable for adult male (AUC = 0.880) den sites. The model containing land cover and elevation best-predicted juvenile (AUC = 0.841) den sites. Adult females spatially segregated from adult males, with dens characterized by higher elevations (mean= 1,412 m, SE = 52) and steeper slopes (mean = 21.9°, SE = 1.1) than adult male (elevation: mean = 1,209 m, SE = 76; slope: mean = 15.6°, SE = 1.9) den sites. Juveniles used a broad range of landscape attributes but did not avoid adult male denning areas. Observed spatial segregation by adult females supports the sex hypothesis of sexual segregation and we suggest is a mechanism to reduce risk of infanticide. Den site selection of adult males is likely related to distribution of food resources during spring.

  13. Prioritizing Sites for Protection and Restoration for Grizzly Bears (Ursus arctos) in Southwestern Alberta, Canada.

    Science.gov (United States)

    Braid, Andrew C R; Nielsen, Scott E

    2015-01-01

    As the influence of human activities on natural systems continues to expand, there is a growing need to prioritize not only pristine sites for protection, but also degraded sites for restoration. We present an approach for simultaneously prioritizing sites for protection and restoration that considers landscape patterns for a threatened population of grizzly bears (Ursus arctos) in southwestern Alberta, Canada. We considered tradeoffs between bottom-up (food resource supply) and top-down (mortality risk from roads) factors affecting seasonal habitat quality for bears. Simulated annealing was used to prioritize source-like sites (high habitat productivity, low mortality risk) for protection, as well as sink-like sites (high habitat productivity, high mortality risk) for restoration. Priority source-like habitats identified key conservation areas where future developments should be limited, whereas priority sink-like habitats identified key areas for mitigating road-related mortality risk with access management. Systematic conservation planning methods can be used to complement traditional habitat-based methods for individual focal species by identifying habitats where conservation actions (both protection and restoration) have the highest potential utility.

  14. Prioritizing Sites for Protection and Restoration for Grizzly Bears (Ursus arctos in Southwestern Alberta, Canada.

    Directory of Open Access Journals (Sweden)

    Andrew C R Braid

    Full Text Available As the influence of human activities on natural systems continues to expand, there is a growing need to prioritize not only pristine sites for protection, but also degraded sites for restoration. We present an approach for simultaneously prioritizing sites for protection and restoration that considers landscape patterns for a threatened population of grizzly bears (Ursus arctos in southwestern Alberta, Canada. We considered tradeoffs between bottom-up (food resource supply and top-down (mortality risk from roads factors affecting seasonal habitat quality for bears. Simulated annealing was used to prioritize source-like sites (high habitat productivity, low mortality risk for protection, as well as sink-like sites (high habitat productivity, high mortality risk for restoration. Priority source-like habitats identified key conservation areas where future developments should be limited, whereas priority sink-like habitats identified key areas for mitigating road-related mortality risk with access management. Systematic conservation planning methods can be used to complement traditional habitat-based methods for individual focal species by identifying habitats where conservation actions (both protection and restoration have the highest potential utility.

  15. Estimating total human-caused mortality from reported mortality using data from radio-instrumented grizzly bears

    Science.gov (United States)

    Cherry, S.; Haroldson, M.A.; Robison-Cox, J.; Schwartz, C.C.

    2002-01-01

    Tracking mortality of the Yellowstone grizzly bear (Ursus arctos horribilis) is an essential issue of the recovery process. Problem bears removed by agencies are well documented. Deaths of radiocollared bears are known or, in many cases, can be reliably inferred. Additionally, the public reports an unknown proportion of deaths of uncollared bears. Estimating the number of non-agency human-caused mortalities is a necessary element that must be factored into the total annual mortality. Here, we describe a method of estimating the number of such deaths from records of reported human-caused bear mortalities. We used a hierarchical Bayesian model with a non-informative prior distribution for the number of deaths. Estimates of reporting rates developed from deaths of radio-instrumented bears from 1983 to 2000 were used to develop beta prior probability distributions that the public will report a death. Twenty-seven known deaths of radio-instrumented bears occurred during this period with 16 reported. Additionally, fates of 23 radio-instrumented bears were unknown and are considered possible unreported mortalities. We describe 3 ways of using this information to specify prior distributions on the probability a death will be reported by the public. We estimated total deaths of noninstrumented bears in running 3-year periods from 1993 to 2000. Thirty-nine known deaths of non-instrumented bears were reported during this period, ranging from 0 to 7/year. Seven possible mortalities were recorded. We applied the method to both sets of mortality data. Results from this method can be combined with agency removals and deaths of collared bears to produce defensible estimates of total mortality over relevant periods and to incorporate uncertainty when evaluating mortality limits established for the Yellowstone grizzly bear population. Assumptions and limitations of this procedure are discussed.

  16. Estimating numbers of females with cubs-of-the-year in the Yellowstone grizzly bear population

    Science.gov (United States)

    Keating, K.A.; Schwartz, C.C.; Haroldson, M.A.; Moody, D.

    2001-01-01

    For grizzly bears (Ursus arctos horribilis) in the Greater Yellowstone Ecosystem (GYE), minimum population size and allowable numbers of human-caused mortalities have been calculated as a function of the number of unique females with cubs-of-the-year (FCUB) seen during a 3- year period. This approach underestimates the total number of FCUB, thereby biasing estimates of population size and sustainable mortality. Also, it does not permit calculation of valid confidence bounds. Many statistical methods can resolve or mitigate these problems, but there is no universal best method. Instead, relative performances of different methods can vary with population size, sample size, and degree of heterogeneity among sighting probabilities for individual animals. We compared 7 nonparametric estimators, using Monte Carlo techniques to assess performances over the range of sampling conditions deemed plausible for the Yellowstone population. Our goal was to estimate the number of FCUB present in the population each year. Our evaluation differed from previous comparisons of such estimators by including sample coverage methods and by treating individual sightings, rather than sample periods, as the sample unit. Consequently, our conclusions also differ from earlier studies. Recommendations regarding estimators and necessary sample sizes are presented, together with estimates of annual numbers of FCUB in the Yellowstone population with bootstrap confidence bounds.

  17. Testing landscape modeling approaches for environmental impact assessment of mining land use on grizzly bears (Ursus arctos horribilis) in the foothills region of west central Alberta

    Energy Technology Data Exchange (ETDEWEB)

    Symbaluk, M.D. [Elk Valley Coal Corp., Hinton, AB (Canada). Cardinal River Operations

    2008-07-01

    The Cheviot open pit coal mine is located on the front range of the Rocky Mountains in Alberta. The environmental impact assessment (EIA) requirements for the mining project included an assessment of the cumulative effects of past, existing, and immanent activities on a 3040 km{sup 2} study area radiating approximately 25 km around the proposed project area. The grizzly bear was identified as a flagship valued ecosystem component (VEC) for assessing the regional cumulative effects of the proposed Cheviot project. In this portion of the study, a grizzly bear habitat effectiveness model was used to monitor grizzly bear response to mining land use in the study area. An investigation of grizzly bear movement paths prior to and during mine disturbances demonstrated that mining land use does not present significant barriers to grizzly bear activities. The study demonstrated the importance of using inductive modelling tools at appropriate scales, as well as the use of site-specific empirical data. It was concluded that continued monitoring of mining sites is needed to ensure that adaptive management processes are improved. A review of the Cheviot cumulative environmental effects (CEA) process was also provided. 17 refs., 1 fig.

  18. Morphological variability and molecular identification of Uncinaria spp. (Nematoda: Ancylostomatidae) from grizzly and black bears: new species or phenotypic plasticity?

    Science.gov (United States)

    Catalano, Stefano; Lejeune, Manigandan; van Paridon, Bradley; Pagan, Christopher A; Wasmuth, James D; Tizzani, Paolo; Duignan, Pádraig J; Nadler, Steven A

    2015-04-01

    The hookworms Uncinaria rauschi Olsen, 1968 and Uncinaria yukonensis ( Wolfgang, 1956 ) were formally described from grizzly ( Ursus arctos horribilis) and black bears ( Ursus americanus ) of North America. We analyzed the intestinal tracts of 4 grizzly and 9 black bears from Alberta and British Columbia, Canada and isolated Uncinaria specimens with anatomical traits never previously documented. We applied morphological and molecular techniques to investigate the taxonomy and phylogeny of these Uncinaria parasites. The morphological analysis supported polymorphism at the vulvar region for females of both U. rauschi and U. yukonensis. The hypothesis of morphological plasticity for U. rauschi and U. yukonensis was confirmed by genetic analysis of the internal transcribed spacers (ITS-1 and ITS-2) of the nuclear ribosomal DNA. Two distinct genotypes were identified, differing at 5 fixed sites for ITS-1 (432 base pairs [bp]) and 7 for ITS-2 (274 bp). Morphometric data for U. rauschi revealed host-related size differences: adult U. rauschi were significantly larger in black bears than in grizzly bears. Interpretation of these results, considering the historical biogeography of North American bears, suggests a relatively recent host-switching event of U. rauschi from black bears to grizzly bears which likely occurred after the end of the Wisconsin glaciation. Phylogenetic maximum parsimony (MP) and maximum likelihood (ML) analyses of the concatenated ITS-1 and ITS-2 datasets strongly supported monophyly of U. rauschi and U. yukonensis and their close relationship with Uncinaria stenocephala (Railliet, 1884), the latter a parasite primarily of canids and felids. Relationships among species within this group, although resolved by ML, were unsupported by MP and bootstrap resampling. The clade of U. rauschi, U. yukonensis, and U. stenocephala was recovered as sister to the clade represented by Uncinaria spp. from otariid pinnipeds. These results support the absence of strict

  19. Development and application of an antibody-based protein microarray to assess physiological stress in grizzly bears (Ursus arctos).

    Science.gov (United States)

    Carlson, Ruth I; Cattet, Marc R L; Sarauer, Bryan L; Nielsen, Scott E; Boulanger, John; Stenhouse, Gordon B; Janz, David M

    2016-01-01

    A novel antibody-based protein microarray was developed that simultaneously determines expression of 31 stress-associated proteins in skin samples collected from free-ranging grizzly bears (Ursus arctos) in Alberta, Canada. The microarray determines proteins belonging to four broad functional categories associated with stress physiology: hypothalamic-pituitary-adrenal axis proteins, apoptosis/cell cycle proteins, cellular stress/proteotoxicity proteins and oxidative stress/inflammation proteins. Small skin samples (50-100 mg) were collected from captured bears using biopsy punches. Proteins were isolated and labelled with fluorescent dyes, with labelled protein homogenates loaded onto microarrays to hybridize with antibodies. Relative protein expression was determined by comparison with a pooled standard skin sample. The assay was sensitive, requiring 80 µg of protein per sample to be run in triplicate on the microarray. Intra-array and inter-array coefficients of variation for individual proteins were generally bears. This suggests that remotely delivered biopsy darts could be used in future sampling. Using generalized linear mixed models, certain proteins within each functional category demonstrated altered expression with respect to differences in year, season, geographical sampling location within Alberta and bear biological parameters, suggesting that these general variables may influence expression of specific proteins in the microarray. Our goal is to apply the protein microarray as a conservation physiology tool that can detect, evaluate and monitor physiological stress in grizzly bears and other species at risk over time in response to environmental change.

  20. 75 FR 63434 - Kootenai National Forest, Lincoln County, Montana; Grizzly Vegetation and Transportation...

    Science.gov (United States)

    2010-10-15

    ... on the threatened Cabinet-Yaak grizzly bears which inhabit the area. Regarding the Grizzly Vegetation... Situation 1 lands which require the agency to ``favor the needs of the grizzly bear when grizzly habitat and... the grizzly bear analysis. DATES: Under 40 CFR 1502.9(c)(4), there is no formal scoping period...

  1. Changing numbers of spawning cutthroat trout in tributary streams of Yellowstone Lake and estimates of grizzly bears visiting streams from DNA

    Science.gov (United States)

    Haroldson, M.A.; Gunther, K.A.; Reinhart, D.P.; Podruzny, S.R.; Cegelski, C.; Waits, L.; Wyman, T.C.; Smith, J.

    2005-01-01

    Spawning Yellowstone cutthroat trout (Oncorhynchus clarki) provide a source of highly digestible energy for grizzly bears (Ursus arctos) that visit tributary streams to Yellowstone Lake during the spring and early summer. During 1985–87, research documented grizzly bears fishing on 61% of the 124 tributary streams to the lake. Using track measurements, it was estimated that a minimum of 44 grizzly bears fished those streams annually. During 1994, non-native lake trout (Salvelinus namaycush) were discovered in Yellowstone Lake. Lake trout are efficient predators and have the potential to reduce the native cutthroat population and negatively impact terrestrial predators that use cutthroat trout as a food resource. In 1997, we began sampling a subset of streams (n = 25) from areas of Yellowstone Lake surveyed during the previous study to determine if changes in spawner numbers or bear use had occurred. Comparisons of peak numbers and duration suggested a considerable decline between study periods in streams in the West Thumb area of the lake. The apparent decline may be due to predation by lake trout. Indices of bear use also declined on West Thumb area streams. We used DNA from hair collected near spawning streams to estimate the minimum number of bears visiting the vicinity of spawning streams. Seventy-four individual bears were identified from 429 hair samples. The annual number of individuals detected ranged from 15 in 1997 to 33 in 2000. Seventy percent of genotypes identified were represented by more than 1 sample, but only 31% of bears were documented more than 1 year of the study. Sixty-two (84%) bears were only documented in 1 segment of the lake, whereas 12 (16%) were found in 2–3 lake segments. Twenty-seven bears were identified from hair collected at multiple streams. One bear was identified on 6 streams in 2 segments of the lake and during 3 years of the study. We used encounter histories derived from DNA and the Jolly-Seber procedure in Program MARK

  2. Multiple estimates of effective population size for monitoring a long-lived vertebrate: An application to Yellowstone grizzly bears

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    Kamath, Pauline L.; Haroldson, Mark A.; Luikart, Gordon; Paetkau, David; Whitman, Craig L.; van Manen, Frank T.

    2015-01-01

    Effective population size (Ne) is a key parameter for monitoring the genetic health of threatened populations because it reflects a population's evolutionary potential and risk of extinction due to genetic stochasticity. However, its application to wildlife monitoring has been limited because it is difficult to measure in natural populations. The isolated and well-studied population of grizzly bears (Ursus arctos) in the Greater Yellowstone Ecosystem provides a rare opportunity to examine the usefulness of different Ne estimators for monitoring. We genotyped 729 Yellowstone grizzly bears using 20 microsatellites and applied three single-sample estimators to examine contemporary trends in generation interval (GI), effective number of breeders (Nb) and Ne during 1982–2007. We also used multisample methods to estimate variance (NeV) and inbreeding Ne (NeI). Single-sample estimates revealed positive trajectories, with over a fourfold increase in Ne (≈100 to 450) and near doubling of the GI (≈8 to 14) from the 1980s to 2000s. NeV (240–319) and NeI (256) were comparable with the harmonic mean single-sample Ne (213) over the time period. Reanalysing historical data, we found NeV increased from ≈80 in the 1910s–1960s to ≈280 in the contemporary population. The estimated ratio of effective to total census size (Ne/Nc) was stable and high (0.42–0.66) compared to previous brown bear studies. These results support independent demographic evidence for Yellowstone grizzly bear population growth since the 1980s. They further demonstrate how genetic monitoring of Ne can complement demographic-based monitoring of Nc and vital rates, providing a valuable tool for wildlife managers.

  3. Multiple estimates of effective population size for monitoring a long-lived vertebrate: an application to Yellowstone grizzly bears.

    Science.gov (United States)

    Kamath, Pauline L; Haroldson, Mark A; Luikart, Gordon; Paetkau, David; Whitman, Craig; van Manen, Frank T

    2015-11-01

    Effective population size (N(e)) is a key parameter for monitoring the genetic health of threatened populations because it reflects a population's evolutionary potential and risk of extinction due to genetic stochasticity. However, its application to wildlife monitoring has been limited because it is difficult to measure in natural populations. The isolated and well-studied population of grizzly bears (Ursus arctos) in the Greater Yellowstone Ecosystem provides a rare opportunity to examine the usefulness of different N(e) estimators for monitoring. We genotyped 729 Yellowstone grizzly bears using 20 microsatellites and applied three single-sample estimators to examine contemporary trends in generation interval (GI), effective number of breeders (N(b)) and N(e) during 1982-2007. We also used multisample methods to estimate variance (N(eV)) and inbreeding N(e) (N(eI)). Single-sample estimates revealed positive trajectories, with over a fourfold increase in N(e) (≈100 to 450) and near doubling of the GI (≈8 to 14) from the 1980s to 2000s. N(eV) (240-319) and N(eI) (256) were comparable with the harmonic mean single-sample N(e) (213) over the time period. Reanalysing historical data, we found N(eV) increased from ≈80 in the 1910s-1960s to ≈280 in the contemporary population. The estimated ratio of effective to total census size (N(e) /N(c)) was stable and high (0.42-0.66) compared to previous brown bear studies. These results support independent demographic evidence for Yellowstone grizzly bear population growth since the 1980s. They further demonstrate how genetic monitoring of N(e) can complement demographic-based monitoring of N(c) and vital rates, providing a valuable tool for wildlife managers.

  4. Decreased bone turnover with balanced resorption and formation prevent cortical bone loss during disuse (hibernation) in grizzly bears (Ursus arctos horribilis).

    Science.gov (United States)

    McGee, Meghan E; Maki, Aaron J; Johnson, Steven E; Nelson, O Lynne; Robbins, Charles T; Donahue, Seth W

    2008-02-01

    Disuse uncouples bone formation from resorption, leading to increased porosity, decreased bone geometrical properties, and decreased bone mineral content which compromises bone mechanical properties and increases fracture risk. However, black bear bone properties are not adversely affected by aging despite annual periods of disuse (i.e., hibernation), which suggests that bears either prevent bone loss during disuse or lose bone and subsequently recover it at a faster rate than other animals. Here we show decreased cortical bone turnover during hibernation with balanced formation and resorption in grizzly bear femurs. Hibernating grizzly bear femurs were less porous and more mineralized, and did not demonstrate any changes in cortical bone geometry or whole bone mechanical properties compared to active grizzly bear femurs. The activation frequency of intracortical remodeling was 75% lower during hibernation than during periods of physical activity, but the normalized mineral apposition rate was unchanged. These data indicate that bone turnover decreases during hibernation, but osteons continue to refill at normal rates. There were no changes in regional variation of porosity, geometry, or remodeling indices in femurs from hibernating bears, indicating that hibernation did not preferentially affect one region of the cortex. Thus, grizzly bears prevent bone loss during disuse by decreasing bone turnover and maintaining balanced formation and resorption, which preserves bone structure and strength. These results support the idea that bears possess a biological mechanism to prevent disuse osteoporosis.

  5. First report of Taenia arctos (Cestoda: Taeniidae) from grizzly (Ursus arctos horribilis) and black bears (Ursus americanus) in North America.

    Science.gov (United States)

    Catalano, Stefano; Lejeune, Manigandan; Verocai, Guilherme G; Duignan, Pádraig J

    2014-04-01

    The cestode Taenia arctos was found at necropsy in the small intestine of a grizzly (Ursus arctos horribilis) and a black bear (Ursus americanus) from Kananaskis Country in southwestern Alberta, Canada. The autolysis of the tapeworm specimens precluded detailed morphological characterization of the parasites but molecular analysis based on mitochondrial DNA cytochrome c oxidase subunit 1 gene confirmed their identity as T. arctos. This is the first report of T. arctos from definitive hosts in North America. Its detection in Canadian grizzly and black bears further supports the Holarctic distribution of this tapeworm species and its specificity for ursids as final hosts. Previously, T. arctos was unambiguously described at its adult stage in brown bears (Ursus arctos arctos) from Finland, and as larval stages in Eurasian elk (Alces alces) from Finland and moose (Alces americanus) from Alaska, USA. Given the morphological similarity between T. arctos and other Taenia species, the present study underlines the potential for misidentification of tapeworm taxa in previous parasitological reports from bears and moose across North America. The biogeographical history of both definitive and intermediate hosts in the Holarctic suggests an ancient interaction between U. arctos, Alces spp., and T. arctos, and a relatively recent host-switching event in U. americanus.

  6. Natural landscape features, human-related attractants, and conflict hotspots: A spatial analysis of human-grizzly bear conflicts

    Science.gov (United States)

    Wilson, S.M.; Madel, M.J.; Mattson, D.J.; Graham, J.M.; Burchfield, J.A.; Belsky, J.M.

    2005-01-01

    There is a long history of conflict in the western United States between humans and grizzly bears (Ursus arctos) involving agricultural attractants. However, little is known about the spatial dimensions of this conflict and the relative importance of different attractants. This study was undertaken to better understand the spatial and functional components of conflict between humans and grizzly bears on privately owned agricultural lands in Montana. Our investigations focused on spatial associations of rivers and creeks, livestock pastures, boneyards (livestock carcass dump sites), beehives, and grizzly bear habitat with reported human-grizzly bear conflicts during 1986-2001. We based our analysis on a survey of 61 of 64 livestock producers in our study in the Rocky Mountain East Front, Montana. With the assistance of livestock and honey producers, we mapped the locations of cattle and sheep pastures, boneyards, and beehives. We used density surface mapping to identify seasonal clusters of conflicts that we term conflict hotspots. Hotspots accounted for 75% of all conflicts and encompassed approximately 8% of the study area. We also differentiated chronic (4 or more years of conflicts) from non-chronic hotspots (fewer than 4 years of conflict). The 10 chronic hotpots accounted for 58% of all conflicts. Based on Monte Carlo simulations, we found that conflict locations were most strongly associated with rivers and creeks followed by sheep lambing areas and fall sheep pastures. Conflicts also were associated with cattle calving areas, spring cow-calf pastures, summer and fall cattle pastures, and boneyards. The Monte Carlo simulations indicated associations between conflict locations and unprotected beehives at specific analysis scales. Protected (fenced) beehives were less likely to experience conflicts than unprotected beehives. Conflicts occurred at a greater rate in riparian and wetland vegetation than would be expected. The majority of conflicts occurred in a

  7. Staying cool in a changing landscape: the influence of maximum daily ambient temperature on grizzly bear habitat selection.

    Science.gov (United States)

    Pigeon, Karine E; Cardinal, Etienne; Stenhouse, Gordon B; Côté, Steeve D

    2016-08-01

    To fulfill their needs, animals are constantly making trade-offs among limiting factors. Although there is growing evidence about the impact of ambient temperature on habitat selection in mammals, the role of environmental conditions and thermoregulation on apex predators is poorly understood. Our objective was to investigate the influence of ambient temperature on habitat selection patterns of grizzly bears in the managed landscape of Alberta, Canada. Grizzly bear habitat selection followed a daily and seasonal pattern that was influenced by ambient temperature, with adult males showing stronger responses than females to warm temperatures. Cutblocks aged 0-20 years provided an abundance of forage but were on average 6 °C warmer than mature conifer stands and 21- to 40-year-old cutblocks. When ambient temperatures increased, the relative change (odds ratio) in the probability of selection for 0- to 20-year-old cutblocks decreased during the hottest part of the day and increased during cooler periods, especially for males. Concurrently, the probability of selection for 21- to 40-year-old cutblocks increased on warmer days. Following plant phenology, the odds of selecting 0- to 20-year-old cutblocks also increased from early to late summer while the odds of selecting 21- to 40-year-old cutblocks decreased. Our results demonstrate that ambient temperatures, and therefore thermal requirements, play a significant role in habitat selection patterns and behaviour of grizzly bears. In a changing climate, large mammals may increasingly need to adjust spatial and temporal selection patterns in response to thermal constraints.

  8. Spatial analysis of factors influencing long-term stress in the grizzly bear (Ursus arctos population of Alberta, Canada.

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    Mathieu L Bourbonnais

    Full Text Available Non-invasive measures for assessing long-term stress in free ranging mammals are an increasingly important approach for understanding physiological responses to landscape conditions. Using a spatially and temporally expansive dataset of hair cortisol concentrations (HCC generated from a threatened grizzly bear (Ursus arctos population in Alberta, Canada, we quantified how variables representing habitat conditions and anthropogenic disturbance impact long-term stress in grizzly bears. We characterized spatial variability in male and female HCC point data using kernel density estimation and quantified variable influence on spatial patterns of male and female HCC stress surfaces using random forests. Separate models were developed for regions inside and outside of parks and protected areas to account for substantial differences in anthropogenic activity and disturbance within the study area. Variance explained in the random forest models ranged from 55.34% to 74.96% for males and 58.15% to 68.46% for females. Predicted HCC levels were higher for females compared to males. Generally, high spatially continuous female HCC levels were associated with parks and protected areas while low-to-moderate levels were associated with increased anthropogenic disturbance. In contrast, male HCC levels were low in parks and protected areas and low-to-moderate in areas with increased anthropogenic disturbance. Spatial variability in gender-specific HCC levels reveal that the type and intensity of external stressors are not uniform across the landscape and that male and female grizzly bears may be exposed to, or perceive, potential stressors differently. We suggest observed spatial patterns of long-term stress may be the result of the availability and distribution of foods related to disturbance features, potential sexual segregation in available habitat selection, and may not be influenced by sources of mortality which represent acute traumas. In this wildlife

  9. Spatial analysis of factors influencing long-term stress in the grizzly bear (Ursus arctos) population of Alberta, Canada.

    Science.gov (United States)

    Bourbonnais, Mathieu L; Nelson, Trisalyn A; Cattet, Marc R L; Darimont, Chris T; Stenhouse, Gordon B

    2013-01-01

    Non-invasive measures for assessing long-term stress in free ranging mammals are an increasingly important approach for understanding physiological responses to landscape conditions. Using a spatially and temporally expansive dataset of hair cortisol concentrations (HCC) generated from a threatened grizzly bear (Ursus arctos) population in Alberta, Canada, we quantified how variables representing habitat conditions and anthropogenic disturbance impact long-term stress in grizzly bears. We characterized spatial variability in male and female HCC point data using kernel density estimation and quantified variable influence on spatial patterns of male and female HCC stress surfaces using random forests. Separate models were developed for regions inside and outside of parks and protected areas to account for substantial differences in anthropogenic activity and disturbance within the study area. Variance explained in the random forest models ranged from 55.34% to 74.96% for males and 58.15% to 68.46% for females. Predicted HCC levels were higher for females compared to males. Generally, high spatially continuous female HCC levels were associated with parks and protected areas while low-to-moderate levels were associated with increased anthropogenic disturbance. In contrast, male HCC levels were low in parks and protected areas and low-to-moderate in areas with increased anthropogenic disturbance. Spatial variability in gender-specific HCC levels reveal that the type and intensity of external stressors are not uniform across the landscape and that male and female grizzly bears may be exposed to, or perceive, potential stressors differently. We suggest observed spatial patterns of long-term stress may be the result of the availability and distribution of foods related to disturbance features, potential sexual segregation in available habitat selection, and may not be influenced by sources of mortality which represent acute traumas. In this wildlife system and others

  10. A Comparison of Grizzly Bear Demographic Parameters Estimated from Non-Spatial and Spatial Open Population Capture-Recapture Models.

    Directory of Open Access Journals (Sweden)

    Jesse Whittington

    Full Text Available Capture-recapture studies are frequently used to monitor the status and trends of wildlife populations. Detection histories from individual animals are used to estimate probability of detection and abundance or density. The accuracy of abundance and density estimates depends on the ability to model factors affecting detection probability. Non-spatial capture-recapture models have recently evolved into spatial capture-recapture models that directly include the effect of distances between an animal's home range centre and trap locations on detection probability. Most studies comparing non-spatial and spatial capture-recapture biases focussed on single year models and no studies have compared the accuracy of demographic parameter estimates from open population models. We applied open population non-spatial and spatial capture-recapture models to three years of grizzly bear DNA-based data from Banff National Park and simulated data sets. The two models produced similar estimates of grizzly bear apparent survival, per capita recruitment, and population growth rates but the spatial capture-recapture models had better fit. Simulations showed that spatial capture-recapture models produced more accurate parameter estimates with better credible interval coverage than non-spatial capture-recapture models. Non-spatial capture-recapture models produced negatively biased estimates of apparent survival and positively biased estimates of per capita recruitment. The spatial capture-recapture grizzly bear population growth rates and 95% highest posterior density averaged across the three years were 0.925 (0.786-1.071 for females, 0.844 (0.703-0.975 for males, and 0.882 (0.779-0.981 for females and males combined. The non-spatial capture-recapture population growth rates were 0.894 (0.758-1.024 for females, 0.825 (0.700-0.948 for males, and 0.863 (0.771-0.957 for both sexes. The combination of low densities, low reproductive rates, and predominantly negative

  11. A Comparison of Grizzly Bear Demographic Parameters Estimated from Non-Spatial and Spatial Open Population Capture-Recapture Models.

    Science.gov (United States)

    Whittington, Jesse; Sawaya, Michael A

    2015-01-01

    Capture-recapture studies are frequently used to monitor the status and trends of wildlife populations. Detection histories from individual animals are used to estimate probability of detection and abundance or density. The accuracy of abundance and density estimates depends on the ability to model factors affecting detection probability. Non-spatial capture-recapture models have recently evolved into spatial capture-recapture models that directly include the effect of distances between an animal's home range centre and trap locations on detection probability. Most studies comparing non-spatial and spatial capture-recapture biases focussed on single year models and no studies have compared the accuracy of demographic parameter estimates from open population models. We applied open population non-spatial and spatial capture-recapture models to three years of grizzly bear DNA-based data from Banff National Park and simulated data sets. The two models produced similar estimates of grizzly bear apparent survival, per capita recruitment, and population growth rates but the spatial capture-recapture models had better fit. Simulations showed that spatial capture-recapture models produced more accurate parameter estimates with better credible interval coverage than non-spatial capture-recapture models. Non-spatial capture-recapture models produced negatively biased estimates of apparent survival and positively biased estimates of per capita recruitment. The spatial capture-recapture grizzly bear population growth rates and 95% highest posterior density averaged across the three years were 0.925 (0.786-1.071) for females, 0.844 (0.703-0.975) for males, and 0.882 (0.779-0.981) for females and males combined. The non-spatial capture-recapture population growth rates were 0.894 (0.758-1.024) for females, 0.825 (0.700-0.948) for males, and 0.863 (0.771-0.957) for both sexes. The combination of low densities, low reproductive rates, and predominantly negative population growth

  12. Evaluating estimators for numbers of females with cubs-of-the-year in the Yellowstone grizzly bear population

    Science.gov (United States)

    Cherry, S.; White, G.C.; Keating, K.A.; Haroldson, Mark A.; Schwartz, Charles C.

    2007-01-01

    Current management of the grizzly bear (Ursus arctos) population in Yellowstone National Park and surrounding areas requires annual estimation of the number of adult female bears with cubs-of-the-year. We examined the performance of nine estimators of population size via simulation. Data were simulated using two methods for different combinations of population size, sample size, and coefficient of variation of individual sighting probabilities. We show that the coefficient of variation does not, by itself, adequately describe the effects of capture heterogeneity, because two different distributions of capture probabilities can have the same coefficient of variation. All estimators produced biased estimates of population size with bias decreasing as effort increased. Based on the simulation results we recommend the Chao estimator for model M h be used to estimate the number of female bears with cubs of the year; however, the estimator of Chao and Shen may also be useful depending on the goals of the research.

  13. Stress and reproductive hormones in grizzly bears reflect nutritional benefits and social consequences of a salmon foraging niche.

    Directory of Open Access Journals (Sweden)

    Heather M Bryan

    Full Text Available Physiological indicators of social and nutritional stress can provide insight into the responses of species to changes in food availability. In coastal British Columbia, Canada, grizzly bears evolved with spawning salmon as an abundant but spatially and temporally constrained food source. Recent and dramatic declines in salmon might have negative consequences on bear health and ultimately fitness. To examine broadly the chronic endocrine effects of a salmon niche, we compared cortisol, progesterone, and testosterone levels in hair from salmon-eating bears from coastal BC (n = 75 with the levels in a reference population from interior BC lacking access to salmon (n = 42. As predicted, testosterone was higher in coastal bears of both sexes relative to interior bears, possibly reflecting higher social density on the coast mediated by salmon availability. We also investigated associations between the amount of salmon individual bears consumed (as measured by stable isotope analysis and cortisol and testosterone in hair. Also as predicted, cortisol decreased with increasing dietary salmon and was higher after a year of low dietary salmon than after a year of high dietary salmon. These findings at two spatial scales suggest that coastal bears might experience nutritional or social stress in response to on-going salmon declines, providing novel insights into the effects of resource availability on fitness-related physiology.

  14. Stress and reproductive hormones in grizzly bears reflect nutritional benefits and social consequences of a salmon foraging niche.

    Science.gov (United States)

    Bryan, Heather M; Darimont, Chris T; Paquet, Paul C; Wynne-Edwards, Katherine E; Smits, Judit E G

    2013-01-01

    Physiological indicators of social and nutritional stress can provide insight into the responses of species to changes in food availability. In coastal British Columbia, Canada, grizzly bears evolved with spawning salmon as an abundant but spatially and temporally constrained food source. Recent and dramatic declines in salmon might have negative consequences on bear health and ultimately fitness. To examine broadly the chronic endocrine effects of a salmon niche, we compared cortisol, progesterone, and testosterone levels in hair from salmon-eating bears from coastal BC (n = 75) with the levels in a reference population from interior BC lacking access to salmon (n = 42). As predicted, testosterone was higher in coastal bears of both sexes relative to interior bears, possibly reflecting higher social density on the coast mediated by salmon availability. We also investigated associations between the amount of salmon individual bears consumed (as measured by stable isotope analysis) and cortisol and testosterone in hair. Also as predicted, cortisol decreased with increasing dietary salmon and was higher after a year of low dietary salmon than after a year of high dietary salmon. These findings at two spatial scales suggest that coastal bears might experience nutritional or social stress in response to on-going salmon declines, providing novel insights into the effects of resource availability on fitness-related physiology.

  15. Dietary protein content alters energy expenditure and composition of the mass gain in grizzly bears (Ursus arctos horribilis).

    Science.gov (United States)

    Felicetti, Laura A; Robbins, Charles T; Shipley, Lisa A

    2003-01-01

    Many fruits contain high levels of available energy but very low levels of protein and other nutrients. The discrepancy between available energy and protein creates a physiological paradox for many animals consuming high-fruit diets, as they will be protein deficient if they eat to meet their minimum energy requirement. We fed young grizzly bears both high-energy pelleted and fruit diets containing from 1.6% to 15.4% protein to examine the role of diet-induced thermogenesis and fat synthesis in dealing with high-energy-low-protein diets. Digestible energy intake at mass maintenance increased 2.1 times, and composition of the gain changed from primarily lean mass to entirely fat when the protein content of the diet decreased from 15.4% to 1.6%. Daily fat gain was up to three times higher in bears fed low-protein diets ad lib., compared with bears consuming the higher-protein diet and gaining mass at the same rate. Thus, bears eating fruit can either consume other foods to increase dietary protein content and reduce energy expenditure, intake, and potentially foraging time or overeat high-fruit diets and use diet-induced thermogenesis and fat synthesis to deal with their skewed energy-to-protein ratio. These are not discrete options but a continuum that creates numerous solutions for balancing energy expenditure, intake, foraging time, fat accumulation, and ultimately fitness, depending on food availability, foraging efficiency, bear size, and body condition.

  16. Interthalamic hematoma secondary to cerebrovascular atherosclerosis in an aged grizzly bear (Ursus arctos horribilis) with primary cardiac schwannoma.

    Science.gov (United States)

    Miller, Andrew David; McDonough, Sean

    2008-12-01

    A 38-year-old intact female Grizzly bear (Ursus arctos horribilis) was evaluated for progressive seizure activity, pale mucous membranes, deficient pupillary light and menace responses, and irregular shallow respiration. Because of poor response to treatment, the animal was euthanized. Gross examination revealed abundant hemorrhage in both lateral ventricles; a large, encapsulated mass within the rostral interthalamic region; and a well-demarcated, round white mass in the apex of the right ventricle. Histologic examination of the interthalamic mass revealed a resolving hematoma composed of stratified layers of fibrin and white blood cells that was surrounded by a thick fibrous capsule. Most meningeal and intraparenchymal blood vessels had multifocal degeneration, fragmentation, and fraying of the internal elastic lamina with prominent intimal proliferations and plaques. The plaques were formed by small numbers of lipid-laden macrophages (foam cells) that were intermixed with occasional lymphocytes and plasma cells. The cardiac mass was composed of pallisading and interlacing spindle cells with parallel nuclei and abundant, pale eosinophilic cytoplasm consistent with a schwannoma.

  17. Positive Reinforcement Training for Blood Collection in Grizzly Bears (Ursus arctos horribilis) Results in Undetectable Elevations in Serum Cortisol Levels: A Preliminary Investigation.

    Science.gov (United States)

    Joyce-Zuniga, Nicole M; Newberry, Ruth C; Robbins, Charles T; Ware, Jasmine V; Jansen, Heiko T; Nelson, O Lynne

    2016-01-01

    Training nonhuman animals in captivity for participation in routine husbandry procedures is believed to produce a lower stress environment compared with undergoing a general anesthetic event for the same procedure. This hypothesis rests largely on anecdotal evidence that the captive subjects appear more relaxed with the trained event. Blood markers of physiological stress responses were evaluated in 4 captive grizzly bears (Ursus arctos horribilis) who were clicker-trained for blood collection versus 4 bears who were chemically immobilized for blood collection. Serum cortisol and immunoglobulin A (IgA) and plasma β-endorphin were measured as indicators of responses to stress. Plasma β-endorphin was not different between the groups. Serum IgA was undetectable in all bears. Serum cortisol was undetectable in all trained bears, whereas chemically immobilized bears had marked cortisol elevations (p positive reinforcement training for routine health procedures to minimize anxiety.

  18. Mating-related behaviour of grizzly bears inhabiting marginal habitat at the periphery of their North American range.

    Science.gov (United States)

    Edwards, Mark A; Derocher, Andrew E

    2015-02-01

    In comparison to core populations, peripheral populations have low density and recruitment, and are subject to different selective pressures, such as environmental conditions, food type and availability, predation, disease, etc., which may result in behavioural modifications to mating. We test the roam-to-mate hypothesis for a peripheral population of grizzly bears (Ursus arctos) at the northern extent of their North American range, in Canada's Arctic. If bears are roaming-to-mate, we predicted greater range size and daily displacement, and more linear movements for receptive animals during the mating period compared to post-mating. In contrast to our predictions, we found that in general range size and displacement increased from mating to post-mating regardless of reproductive status. When considered across both periods, females with cubs-of-the-year had smaller range use metrics than other reproductive groups, which we attribute to a counter-strategy against sexually selected infanticide and the reduced mobility of cubs. Linearity of movements remained near zero during both periods across all groups, suggesting tortuous movements more characteristic of foraging than of mate-searching. We suggest that for this population, finding quality habitat takes precedence over mate-searching in this marginal Arctic landscape. Alternatively, a more monogamous mating system and sequestering behaviour may have obscured movement differences between the two periods. The behavioural differences in mating that we observed from what is typical of core populations may reflect local adaptation to marginal conditions and could benefit the species in the face of ongoing environmental change.

  19. Genetic relationships of grizzly bears (Ursus arctos) in the Prudhoe Bay region of Alaska: inference from microsatellite DNA, mitochondrial DNA, and field observations.

    Science.gov (United States)

    Cronin, M; Shideler, R; Hechtel, J; Strobeck, C; Paetkau, D

    1999-01-01

    Grizzly bears are abundant in the region of the Prudhoe Bay oil fields in northern Alaska. We used field observations and molecular genetic data to identify parent-offspring and sibling relationships among bears in this region. We determined genotypes at 14 microsatellite DNA loci and the cytochrome b gene of mitochondrial DNA (mtDNA) for 36 bears. We identified 17 possible mother-offspring pairs and 8 possible father-offspring pairs. This includes verification of the relationships of 14 mother-offspring pairs identified from field observations. Three additional mother-offspring pairs and all eight father-offspring pairs were determined from genetic and age data. Relatedness coefficients based on numbers of shared alleles between individuals were as expected: approximately 0.50 for parent-offspring and sibling pairs and approximately 0.75 for a father-offspring pair resulting from a father-daughter mating. The level of genetic variation (mean number of alleles per locus = 6.6, mean heterozygosity = 70%) and allele frequencies in grizzly bears in the Prudhoe Bay region are similar to those in other parts of the species' range.

  20. Landscape features and attractants that predispose grizzly bears to risk of conflicts with humans: A spatial and temporal analysis on privately owned agricultural land

    Science.gov (United States)

    Wilson, Seth Mark

    Grizzly bear (Ursus arctos) deaths in the US tend to be concentrated on the periphery of core habitats. These deaths were often preceded by conflicts with humans. Management removals of "nuisance" and or habituated grizzly bears are a leading cause of death in many populations. This exploratory study focuses on the conditions that lead to human-grizzly bear conflicts on private lands near core habitat. I examined spatial associations among reported human-grizzly bear conflicts during 1986--2001, landscape features, and agricultural-attractants in north-central Montana. I surveyed 61 of a possible 64 active livestock related land users and I used geographic information system (GIS) techniques to collect information on cattle and sheep pasture locations, seasons of use, and bone yard (carcass dumps) and beehive locations. I used GIS spatial analyses, univariate tests, and logistic regression models to explore the associations among conflicts, landscape features, and attractants. A majority (75%) of conflicts were found in distinct seasonal conflict hotspots. Conflict hotspots with spatial overlap were associated with riparian vegetation, bone yards, and beehives in close proximity to one another and accounted for 62% of all conflicts. Consistently available seasonal attractants in overlapping hotspots such as calving areas, sheep lambing areas and spring, summer, and fall sheep and cattle pastures appear to perpetuate the occurrence of conflicts. I found that lambing areas and spring and summer sheep pastures were strongly associated with conflict locations as were cattle calving areas, spring cow/calf pastures, fall pastures, and bone yards. Logistic regression modeling revealed that the presence of riparian vegetation within a 1.6 km search radius strongly influenced the likelihood of conflict. After controlling for riparian vegetation, I found that unmanaged bone yards, unfenced and fenced beehives, all increased the odds of conflict. For every 1 km moved away

  1. Environmental factors and habitat use influence body condition of individuals in a species at risk, the grizzly bear.

    Science.gov (United States)

    Bourbonnais, Mathieu L; Nelson, Trisalyn A; Cattet, Marc R L; Darimont, Chris T; Stenhouse, Gordon B; Janz, David M

    2014-01-01

    Metrics used to quantify the condition or physiological states of individuals provide proactive mechanisms for understanding population dynamics in the context of environmental factors. Our study examined how anthropogenic disturbance, habitat characteristics and hair cortisol concentrations interpreted as a sex-specific indicator of potential habitat net-energy demand affect the body condition of grizzly bears (n = 163) in a threatened population in Alberta, Canada. We quantified environmental variables by modelling spatial patterns of individual habitat use based on global positioning system telemetry data. After controlling for gender, age and capture effects, we assessed the influence of biological and environmental variables on body condition using linear mixed-effects models in an information theoretical approach. Our strongest model suggested that body condition was improved when patterns of habitat use included greater vegetation productivity, increased influence of forest harvest blocks and oil and gas well sites, and a higher percentage of regenerating and coniferous forest. However, body condition was negatively affected by habitat use in close proximity to roads and in areas where potential energetic demands were high. Poor body condition was also associated with increased selection of parks and protected areas and greater seasonal vegetation productivity. Adult females, females with cubs-of-year, juvenile females and juvenile males were in poorer body condition compared with adult males, suggesting that intra-specific competition and differences in habitat use based on gender and age may influence body condition dynamics. Habitat net-energy demand also tended to be higher in areas used by females which, combined with observed trends in body condition, could affect reproductive success in this threatened population. Our results highlight the importance of considering spatiotemporal variability in environmental factors and habitat use when assessing

  2. Population fragmentation and inter-ecosystem movements of grizzly bears in Western Canada and the Northern United States

    Science.gov (United States)

    Proctor, M.F.; Paetkau, David; McLellan, B.N.; Stenhouse, G.B.; Kendall, K.C.; Mace, R.D.; Kasworm, W.F.; Servheen, C.; Lausen, C.L.; Gibeau, M.L.; Wakkinen, W.L.; Haroldson, M.A.; Mowat, G.; Apps, C.D.; Ciarniello, L.M.; Barclay, R.M.R.; Boyce, M.S.; Schwartz, C.C.; Strobeck, C.

    2012-01-01

    Population fragmentation compromises population viability, reduces a species ability to respond to climate change, and ultimately may reduce biodiversity. We studied the current state and potential causes of fragmentation in grizzly bears over approximately 1,000,000 km 2 of western Canada, the northern United States (US), and southeast Alaska. We compiled much of our data from projects undertaken with a variety of research objectives including population estimation and trend, landscape fragmentation, habitat selection, vital rates, and response to human development. Our primary analytical techniques stemmed from genetic analysis of 3,134 bears, supplemented with radiotelemetry data from 792 bears. We used 15 locus microsatellite data coupled withmeasures of genetic distance, isolation-by-distance (IBD) analysis, analysis of covariance (ANCOVA), linear multiple regression, multi-factorial correspondence analysis (to identify population divisions or fractures with no a priori assumption of group membership), and population-assignment methods to detect individual migrants between immediately adjacent areas. These data corroborated observations of inter-area movements from our telemetry database. In northern areas, we found a spatial genetic pattern of IBD, although there was evidence of natural fragmentation from the rugged heavily glaciated coast mountains of British Columbia (BC) and the Yukon. These results contrasted with the spatial pattern of fragmentation in more southern parts of their distribution. Near the Canada-US border area, we found extensive fragmentation that corresponded to settled mountain valleys andmajor highways. Genetic distances across developed valleys were elevated relative to those across undeveloped valleys in central and northern BC. In disturbed areas, most inter-area movements detected were made by male bears, with few female migrants identified. North-south movements within mountain ranges (Mts) and across BC Highway 3 were more common

  3. Using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to characterize copper, zinc and mercury along grizzly bear hair providing estimate of diet

    Energy Technology Data Exchange (ETDEWEB)

    Noël, Marie, E-mail: marie.noel@stantec.com [Stantec Consulting Ltd. 2042 Mills Road, Unit 11, Sidney BC V8L 4X2 (Canada); Christensen, Jennie R., E-mail: jennie.christensen@stantec.com [Stantec Consulting Ltd. 2042 Mills Road, Unit 11, Sidney BC V8L 4X2 (Canada); Spence, Jody, E-mail: jodys@uvic.ca [School of Earth and Ocean Sciences, Bob Wright Centre A405, University of Victoria, PO BOX 3065 STN CSC, Victoria, BC V8W 3V6 (Canada); Robbins, Charles T., E-mail: ctrobbins@wsu.edu [School of the Environment and School of Biological Sciences, Washington State University, Pullman, WA 99164-4236 (United States)

    2015-10-01

    We enhanced an existing technique, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), to function as a non-lethal tool in the temporal characterization of trace element exposure in wild mammals. Mercury (Hg), copper (Cu), cadmium (Cd), lead (Pb), iron (Fe) and zinc (Zn) were analyzed along the hair of captive and wild grizzly bears (Ursus arctos horribilis). Laser parameters were optimized (consecutive 2000 μm line scans along the middle line of the hair at a speed of 50 μm/s; spot size = 30 μm) for consistent ablation of the hair. A pressed pellet of reference material DOLT-2 and sulfur were used as external and internal standards, respectively. Our newly adapted method passed the quality control tests with strong correlations between trace element concentrations obtained using LA-ICP-MS and those obtained with regular solution-ICP-MS (r{sup 2} = 0.92, 0.98, 0.63, 0.57, 0.99 and 0.90 for Hg, Fe, Cu, Zn, Cd and Pb, respectively). Cross-correlation analyses revealed good reproducibility between trace element patterns obtained from hair collected from the same bear. One exception was Cd for which external contamination was observed resulting in poor reproducibility. In order to validate the method, we used LA-ICP-MS on the hair of five captive grizzly bears fed known and varying amounts of cutthroat trout over a period of 33 days. Trace element patterns along the hair revealed strong Hg, Cu and Zn signals coinciding with fish consumption. Accordingly, significant correlations between Hg, Cu, and Zn in the hair and Hg, Cu, and Zn intake were evident and we were able to develop accumulation models for each of these elements. While the use of LA-ICP-MS for the monitoring of trace elements in wildlife is in its infancy, this study highlights the robustness and applicability of this newly adapted method. - Highlights: • LA-ICP-MS provides temporal trace metal exposure information for wild grizzly bears. • Cu and Zn temporal exposures provide

  4. Using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to characterize copper, zinc and mercury along grizzly bear hair providing estimate of diet.

    Science.gov (United States)

    Noël, Marie; Christensen, Jennie R; Spence, Jody; Robbins, Charles T

    2015-10-01

    We enhanced an existing technique, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), to function as a non-lethal tool in the temporal characterization of trace element exposure in wild mammals. Mercury (Hg), copper (Cu), cadmium (Cd), lead (Pb), iron (Fe) and zinc (Zn) were analyzed along the hair of captive and wild grizzly bears (Ursus arctos horribilis). Laser parameters were optimized (consecutive 2000 μm line scans along the middle line of the hair at a speed of 50 μm/s; spot size=30 μm) for consistent ablation of the hair. A pressed pellet of reference material DOLT-2 and sulfur were used as external and internal standards, respectively. Our newly adapted method passed the quality control tests with strong correlations between trace element concentrations obtained using LA-ICP-MS and those obtained with regular solution-ICP-MS (r(2)=0.92, 0.98, 0.63, 0.57, 0.99 and 0.90 for Hg, Fe, Cu, Zn, Cd and Pb, respectively). Cross-correlation analyses revealed good reproducibility between trace element patterns obtained from hair collected from the same bear. One exception was Cd for which external contamination was observed resulting in poor reproducibility. In order to validate the method, we used LA-ICP-MS on the hair of five captive grizzly bears fed known and varying amounts of cutthroat trout over a period of 33 days. Trace element patterns along the hair revealed strong Hg, Cu and Zn signals coinciding with fish consumption. Accordingly, significant correlations between Hg, Cu, and Zn in the hair and Hg, Cu, and Zn intake were evident and we were able to develop accumulation models for each of these elements. While the use of LA-ICP-MS for the monitoring of trace elements in wildlife is in its infancy, this study highlights the robustness and applicability of this newly adapted method.

  5. Audubon Wildlife Adventures. Grizzly Guidebook. School Edition.

    Science.gov (United States)

    National Audubon Society, Washington, DC.

    This program introduces the young computer players to the world of the grizzly bear, the largest land carnivore in North America. Through a series of four interactive stories, players learn of the bear's habits and human activities that have brought it close to extinction. Playing the part of a park ranger, a research biologist or a natural…

  6. Insights into the latent multinomial model through mark-resight data on female grizzly bears with cubs-of-the-year

    Science.gov (United States)

    Higgs, Megan D.; Link, William; White, Gary C.; Haroldson, Mark A.; Bjornlie, Daniel D

    2013-01-01

    Mark-resight designs for estimation of population abundance are common and attractive to researchers. However, inference from such designs is very limited when faced with sparse data, either from a low number of marked animals, a low probability of detection, or both. In the Greater Yellowstone Ecosystem, yearly mark-resight data are collected for female grizzly bears with cubs-of-the-year (FCOY), and inference suffers from both limitations. To overcome difficulties due to sparseness, we assume homogeneity in sighting probabilities over 16 years of bi-annual aerial surveys. We model counts of marked and unmarked animals as multinomial random variables, using the capture frequencies of marked animals for inference about the latent multinomial frequencies for unmarked animals. We discuss undesirable behavior of the commonly used discrete uniform prior distribution on the population size parameter and provide OpenBUGS code for fitting such models. The application provides valuable insights into subtleties of implementing Bayesian inference for latent multinomial models. We tie the discussion to our application, though the insights are broadly useful for applications of the latent multinomial model.

  7. Increased cardiac alpha-myosin heavy chain in left atria and decreased myocardial insulin-like growth factor (Igf-I) expression accompany low heart rate in hibernating grizzly bears.

    Science.gov (United States)

    Barrows, N D; Nelson, O L; Robbins, C T; Rourke, B C

    2011-01-01

    Grizzly bears (Ursus arctos horribilis) tolerate extended periods of extremely low heart rate during hibernation without developing congestive heart failure or cardiac chamber dilation. Left ventricular atrophy and decreased left ventricular compliance have been reported in this species during hibernation. We evaluated the myocardial response to significantly reduced heart rate during hibernation by measuring relative myosin heavy-chain (MyHC) isoform expression and expression of a set of genes important to muscle plasticity and mass regulation in the left atria and left ventricles of active and hibernating bears. We supplemented these data with measurements of systolic and diastolic function via echocardiography in unanesthetized grizzly bears. Atrial strain imaging revealed decreased atrial contractility, decreased expansion/reservoir function (increased atrial stiffness), and decreased passive-filling function (increased ventricular stiffness) in hibernating bears. Relative MyHC-α protein expression increased significantly in the atrium during hibernation. The left ventricle expressed 100% MyHC-β protein in both groups. Insulin-like growth factor (IGF-I) mRNA expression was reduced by ∼50% in both chambers during hibernation, consistent with the ventricular atrophy observed in these bears. Interestingly, mRNA expression of the atrophy-related ubiquitin ligases Muscle Atrophy F-box (MAFBx) and Muscle Ring Finger 1 did not increase, nor did expression of myostatin or hypoxia-inducible factor 1α (HIF-1α). We report atrium-specific decreases of 40% and 50%, respectively, in MAFBx and creatine kinase mRNA expression during hibernation. Decreased creatine kinase expression is consistent with lowered energy requirements and could relate to reduced atrial emptying function during hibernation. Taken together with our hemodynamic assessment, these data suggest a potential downregulation of atrial chamber function during hibernation to prevent fatigue and dilation

  8. The salmon bears: giants of the great bear rainforest

    National Research Council Canada - National Science Library

    McAllister, I; Read, N

    2010-01-01

    The Salmon Bears explores the delicate balance that exists between the grizzly, black and spirit bears of the Great Bear Rainforest and their natural environment on the central coast of British Columbia...

  9. Grizzly Usage and Theory Manual

    Energy Technology Data Exchange (ETDEWEB)

    Spencer, B. W. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Backman, M. [Univ. of Tennessee, Knoxville, TN (United States); Chakraborty, P. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Schwen, D. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Zhang, Y. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Huang, H. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Bai, X. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Jiang, W. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-03-01

    Grizzly is a multiphysics simulation code for characterizing the behavior of nuclear power plant (NPP) structures, systems and components (SSCs) subjected to a variety of age-related aging mechanisms. Grizzly simulates both the progression of aging processes, as well as the capacity of aged components to safely perform. This initial beta release of Grizzly includes capabilities for engineering-scale thermo-mechanical analysis of reactor pressure vessels (RPVs). Grizzly will ultimately include capabilities for a wide range of components and materials. Grizzly is in a state of constant development, and future releases will broaden the capabilities of this code for RPV analysis, as well as expand it to address degradation in other critical NPP components.

  10. Anodic oxidation of stilbenes bearing electron-withdrawing ring substituents

    Energy Technology Data Exchange (ETDEWEB)

    Halas, Summer M.; Okyne, Kwame; Fry, Albert J

    2003-06-15

    A number of disubstituted stilbenes bearing either two strong electron-withdrawing groups or one electron-withdrawing and one electron-donating group were synthesized and anodically oxidized in a divided cell in methanol at a carbon anode. A variety of types of products were obtained, most of which have never been observed upon oxidation of alkenes not bearing electron-withdrawing groups. A mechanistic scheme involving 2-methoxy-1,2-diarylethyl cations as key intermediates can account for all of the observed products. The nature of the products from each alkene is strongly correlated with the sum of the Hammett {sigma}{sup +} values of the ring substituents.

  11. Bears, Big and Little. Young Discovery Library Series.

    Science.gov (United States)

    Pfeffer, Pierre

    This book is written for children 5 through 10. Part of a series designed to develop their curiosity, fascinate them and educate them, this volume describes: (1) the eight species of bears, including black bear, brown bear, grizzly bear, spectacled bear, sun bear, sloth bear, polar bear, and giant panda; (2) geographical habitats of bears; (3)…

  12. GRIZZLY/FAVOR Interface Project Report

    Energy Technology Data Exchange (ETDEWEB)

    Dickson, Terry L [ORNL; Williams, Paul T [ORNL; Yin, Shengjun [ORNL; Klasky, Hilda B [ORNL; Tadinada, Sashi [ORNL; Bass, Bennett Richard [ORNL

    2013-06-01

    As part of the Light Water Reactor Sustainability (LWRS) Program, the objective of the GRIZZLY/FAVOR Interface project is to create the capability to apply GRIZZLY 3-D finite element (thermal and stress) analysis results as input to FAVOR probabilistic fracture mechanics (PFM) analyses. The one benefit of FAVOR to Grizzly is the PROBABILISTIC capability. This document describes the implementation of the GRIZZLY/FAVOR Interface, the preliminary verification and tests results and a user guide that provides detailed step-by-step instructions to run the program.

  13. Bear

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The famous physicist made for his scholars this riddle. A fellow encountered a bear in a wasteland. There was nobody else there. Both were frightened and ran away. Fellow to the north, bear to the west. Suddenly the fellow stopped, aimed his gun to the south and shot the bear. What colour was the bear?

  14. In bear country: peaceful co-existence with a touchy wilderness icon starting to look possible

    Energy Technology Data Exchange (ETDEWEB)

    Podlubny, J.

    2002-10-07

    How oil and gas companies have harnessed location data maps and satellite communication technology to help resource developers to map out new roads and pipelines in the grizzly bear habitat of western Alberta is described. The high-tech approach is part of the Foot Hills Model Forest Grizzly Bear Study project, operating out of Hinton, Alberta, which focuses on the effects of industrial activity on the Alberta grizzly bear. Since the project's inception three years ago a library of data has been collected with a tool known as the GPS collar. This collar attached to more than 70 bears enabled scientists to add new dimensions of precision and intimacy to the tracking of grizzly bears. The maps created from data captured by the collars have been used by forestry and oil and gas industry personnel to help establish working relationships with grizzly bears by using the information as a guide to decisions on which routes are best suited for road and pipeline projects, i.e. which ones can be forecast to have the least effect on bears. The study is the first that has generated scientific information which is being used in a practical way to help preserve grizzly bears in the wild. At least one pipeline route has been changed when the company found out, through the mapping technology, that an area affected by the originally proposed route was an important grizzly bear habitat. The information also has been used in conjunction with developing new roads, mining locations and other activities that involve grizzly bear habitats. In addition to these practical industry-related applications the study also focuses on collecting new information about grizzly bears, clearing up bear myths, making discoveries about bear DNA, creating new trapping techniques and the best drugs to use when putting on collars and ear tags.

  15. Recycling of metal bearing electronic scrap in a plasma furnace

    Science.gov (United States)

    Jarosz, Piotr; Małecki, Stanisław; Gargul, Krzysztof

    2011-12-01

    The recycling of electronic waste and the recovery of valuable components are large problems in the modern world economy. This paper presents the effects of melting sorted electronic scrap in a plasma furnace. Printed circuit boards, cables, and windings were processed separately. The characteristics of the obtained products (i.e., alloy metal, slag, dust, and gases) are presented. A method of their further processing in order to obtain commercial products is proposed. Because of the chemical composition and physical properties, the waste slag is environmentally inert and can be used for the production of abrasives. Process dusts containing large amounts of carbon and its compounds have a high calorific value. That makes it possible to use them for energy generation. The gas has a high calorific value, and its afterburning combined with energy recovery is necessary.

  16. TRANSMISSION ELECTRON MICROSCOPY STUDY OF HELIUM BEARING FUSION WELDS

    Energy Technology Data Exchange (ETDEWEB)

    Tosten, M; Michael Morgan, M

    2008-12-12

    A transmission electron microscopy (TEM) study was conducted to characterize the helium bubble distributions in tritium-charged-and-aged 304L and 21Cr-6Ni-9Mn stainless steel fusion welds containing approximately 150 appm helium-3. TEM foils were prepared from C-shaped fracture toughness test specimens containing {delta} ferrite levels ranging from 4 to 33 volume percent. The weld microstructures in the low ferrite welds consisted mostly of austenite and discontinuous, skeletal {delta} ferrite. In welds with higher levels of {delta} ferrite, the ferrite was more continuous and, in some areas of the 33 volume percent sample, was the matrix/majority phase. The helium bubble microstructures observed were similar in all samples. Bubbles were found in the austenite but not in the {delta} ferrite. In the austenite, bubbles had nucleated homogeneously in the grain interiors and heterogeneously on dislocations. Bubbles were not found on any austenite/austenite grain boundaries or at the austenite/{delta} ferrite interphase interfaces. Bubbles were not observed in the {delta} ferrite because of the combined effects of the low solubility and rapid diffusion of tritium through the {delta} ferrite which limited the amount of helium present to form visible bubbles.

  17. Grizzly Substation Fiber Optics : Environmental Assessment.

    Energy Technology Data Exchange (ETDEWEB)

    United States. Bonneville Power Administration.

    1998-02-01

    This notice announces BPA`s decision to construct, operate, and maintain the Grizzly Substation Fiber Optic Project (Project). This Project is part of a continuing effort by BPA to complete a regionwide upgrade of its existing telecommunications system. The US Forest Service and BPA jointly prepared the Grizzly Substation Fiber Optic Project Environmental Assessment (EA) (DOE/EA-1241) evaluating the potential environmental impacts of the Proposed Action, the Underground Installation Alternative, and the No Action Alternative. Based on the analysis in the EA, the US Forest Service and BPA have determined that the Proposed Action is not a major Federal action significantly affecting the quality of the human environment, within the meaning of the National Environmental Policy Act (NEPA) of 1969. Therefore, the preparation of an Environmental Impact Statement (EIS) is not required and BPA is issuing this FONSI. The US Forest Service has separately issued a FONSI and Decision Notice authorizing BPA to construct, operate, and maintain the Project within the Crooked River National Grassland (Grassland).

  18. Genetic connectivity for two bear species at wildlife crossing structures in Banff National Park.

    Science.gov (United States)

    Sawaya, Michael A; Kalinowski, Steven T; Clevenger, Anthony P

    2014-04-01

    Roads can fragment and isolate wildlife populations, which will eventually decrease genetic diversity within populations. Wildlife crossing structures may counteract these impacts, but most crossings are relatively new, and there is little evidence that they facilitate gene flow. We conducted a three-year research project in Banff National Park, Alberta, to evaluate the effectiveness of wildlife crossings to provide genetic connectivity. Our main objective was to determine how the Trans-Canada Highway and crossing structures along it affect gene flow in grizzly (Ursus arctos) and black bears (Ursus americanus). We compared genetic data generated from wildlife crossings with data collected from greater bear populations. We detected a genetic discontinuity at the highway in grizzly bears but not in black bears. We assigned grizzly bears that used crossings to populations north and south of the highway, providing evidence of bidirectional gene flow and genetic admixture. Parentage tests showed that 47% of black bears and 27% of grizzly bears that used crossings successfully bred, including multiple males and females of both species. Differentiating between dispersal and gene flow is difficult, but we documented gene flow by showing migration, reproduction and genetic admixture. We conclude that wildlife crossings allow sufficient gene flow to prevent genetic isolation.

  19. Immobilization of Wyoming bears using carfentanil and xylazine.

    Science.gov (United States)

    Kreeger, Terry J; Bjornlie, Dan; Thompson, Dan; Clapp, Justin; Clark, Colby; Hansen, Cole; Huizenga, Matt; Lockwood, Sam

    2013-07-01

    Seven grizzly (Ursus arctos; four male, three female) and three black (Ursus americanus; two male, one female) bears caught in culvert traps or leg snares were immobilized in northwestern Wyoming with carfentanil and xylazine at doses, respectively, of 0.011 ± 0.001 and 0.12 ± 0.01 mg/kg for grizzly bears and 0.014 ± 0.002 and 0.15 ± 0.04 mg/kg for black bears. These drugs were antagonized with 1 mg/kg naltrexone and 2 mg/kg tolazoline. Induction and recovery times, respectively, were 4.3 ± 0.5 and 7.1 ± 0.8 min for grizzly bears and 5.2 ± 0.4 and 9.1 ± 2.2 min for black bears. Inductions were smooth and uneventful. Recoveries were characterized initially by increased respiration followed by raising of the head, which quickly led to a full recovery, with the bears recognizing and avoiding humans and moving away, maneuvering around obstacles. All bears experienced respiratory depression, which did not significantly improve with supplemental oxygen on the basis of pulse oximetry (P=0.56). Rectal temperatures were normothermic. Carfentanil-xylazine immobilization of bears provided significant advantages over other drug regimens, including small drug volumes, predictable inductions, quick and complete recoveries, and lower costs. On the basis of these data, both grizzly and black bears can be immobilized effectively with 0.01 mg/kg carfentanil and 0.1 mg/kg xylazine.

  20. Contrasting past and current numbers of bears visiting Yellowstone cutthroat trout streams

    Science.gov (United States)

    Haroldson, Mark A.; Schwartz, Charles C.; , JUSTIN E. TEISBERG; , Kerry A. Gunther; , JENNIFER K. FORTIN; , CHARLES T. ROBBINS

    2014-01-01

    Spawning cutthroat trout (Oncorhynchus clarkii bouvieri) were historically abundant within tributary streams of Yellowstone Lake within Yellowstone National Park and were a highly digestible source of energy and protein for Yellowstone’s grizzly bears (Ursus arctos) and black bears (U. americanus). The cutthroat trout population has subsequently declined since the introduction of non-native lake trout (Salvelinus namaycush), and in response to effects of drought and whirling disease (Myxobolus cerebralis). The trout population, duration of spawning runs, and indices of bear use of spawning streams had declined in some regions of the lake by 1997–2000. We initiated a 3-year study in 2007 to assess whether numbers of spawning fish, black bears, and grizzly bears within and alongside stream corridors had changed since 1997– 2000. We estimated numbers of grizzly bears and black bears by first compiling encounter histories of individual bears visiting 48 hair-snag sites along 35 historically fished streams.We analyzed DNA encounter histories with Pradel-recruitment and Jolly-Seber (POPAN) capture-mark-recapture models. When compared to 1997–2000, the current number of spawning cutthroat trout per stream and the number of streams with cutthroat trout has decreased. We estimated that 48 (95% CI¼42–56) male and 23 (95% CI¼21–27) female grizzly bears visited the historically fished tributary streams during our study. In any 1- year, 46 to 59 independent grizzly bears (8–10% of estimated Greater Yellowstone Ecosystem population) visited these streams. When compared with estimates from the 1997 to 2000 study and adjusted for equal effort, the number of grizzly bears using the stream corridors decreased by 63%. Additionally, the number of black bears decreased between 64% and 84%. We also document an increased proportion of bears of both species visiting front-country (i.e., near human development) streams. With the recovery of cutthroat trout, we suggest bears

  1. Characterization of plutonium-bearing wastes by chemical analysis and analytical electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Behrens, R.G. [Los Alamos National Lab., NM (United States); Buck, E.C.; Dietz, N.L.; Bates, J.K.; Van Deventer, E.; Chaiko, D.J. [Argonne National Lab., IL (United States)

    1995-09-01

    This report summarizes the results of characterization studies of plutonium-bearing wastes produced at the US Department of Energy weapons production facilities. Several different solid wastes were characterized, including incinerator ash and ash heels from Rocky Flats Plant and Los Alamos National Laboratory; sand, stag, and crucible waste from Hanford; and LECO crucibles from the Savannah River Site. These materials were characterized by chemical analysis and analytical electron microscopy. The results showed the presence of discrete PuO{sub 2}PuO{sub 2{minus}x}, and Pu{sub 4}O{sub 7} phases, of about 1{mu}m or less in size, in all of the samples examined. In addition, a number of amorphous phases were present that contained plutonium. In all the ash and ash heel samples examined, plutonium phases were found that were completely surrounded by silicate matrices. Consequently, to achieve optimum plutonium recovery in any chemical extraction process, extraction would have to be coupled with ultrafine grinding to average particle sizes of less than 1 {mu}m to liberate the plutonium from the surrounding inert matrix.

  2. Crystal Plasticity Model of Reactor Pressure Vessel Embrittlement in GRIZZLY

    Energy Technology Data Exchange (ETDEWEB)

    Chakraborty, Pritam [Idaho National Laboratory (INL), Idaho Falls, ID (United States); Biner, Suleyman Bulent [Idaho National Laboratory (INL), Idaho Falls, ID (United States); Zhang, Yongfeng [Idaho National Laboratory (INL), Idaho Falls, ID (United States); Spencer, Benjamin Whiting [Idaho National Laboratory (INL), Idaho Falls, ID (United States)

    2015-07-01

    The integrity of reactor pressure vessels (RPVs) is of utmost importance to ensure safe operation of nuclear reactors under extended lifetime. Microstructure-scale models at various length and time scales, coupled concurrently or through homogenization methods, can play a crucial role in understanding and quantifying irradiation-induced defect production, growth and their influence on mechanical behavior of RPV steels. A multi-scale approach, involving atomistic, meso- and engineering-scale models, is currently being pursued within the GRIZZLY project to understand and quantify irradiation-induced embrittlement of RPV steels. Within this framework, a dislocation-density based crystal plasticity model has been developed in GRIZZLY that captures the effect of irradiation-induced defects on the flow stress behavior and is presented in this report. The present formulation accounts for the interaction between self-interstitial loops and matrix dislocations. The model predictions have been validated with experiments and dislocation dynamics simulation.

  3. The history of effective population size and genetic diversity in the Yellowstone grizzly (Ursus arctos): implications for conservation.

    Science.gov (United States)

    Miller, Craig R; Waits, Lisette P

    2003-04-01

    Protein, mtDNA, and nuclear microsatellite DNA analyses have demonstrated that the Yellowstone grizzly bear has low levels of genetic variability compared with other Ursus arctos populations. Researchers have attributed this difference to inbreeding during a century of anthropogenic isolation and population size reduction. We test this hypothesis and assess the seriousness of genetic threats by generating microsatellite data for 110 museum specimens collected between 1912 and 1981. A loss of variability is detected, but it is much less severe than hypothesized. Variance in allele frequencies over time is used to estimate an effective population size of approximately 80 across the 20th century and >100 currently. The viability of the population is unlikely to be substantially reduced by genetic factors in the next several generations. However, gene flow from outside populations will be beneficial in avoiding inbreeding and the erosion of genetic diversity in the future.

  4. 3D J-Integral Capability in Grizzly

    Energy Technology Data Exchange (ETDEWEB)

    Benjamin Spencer; Marie Backman; Pritam Chakraborty; William Hoffman

    2014-09-01

    This report summarizes work done to develop a capability to evaluate fracture contour J-Integrals in 3D in the Grizzly code. In the current fiscal year, a previously-developed 2D implementation of a J-Integral evaluation capability has been extended to work in 3D, and to include terms due both to mechanically-induced strains and due to gradients in thermal strains. This capability has been verified against a benchmark solution on a model of a curved crack front in 3D. The thermal term in this integral has been verified against a benchmark problem with a thermal gradient. These developments are part of a larger effort to develop Grizzly as a tool that can be used to predict the evolution of aging processes in nuclear power plant systems, structures, and components, and assess their capacity after being subjected to those aging processes. The capabilities described here have been developed to enable evaluations of Mode- stress intensity factors on axis-aligned flaws in reactor pressure vessels. These can be compared with the fracture toughness of the material to determine whether a pre-existing flaw would begin to propagate during a pos- tulated pressurized thermal shock accident. This report includes a demonstration calculation to show how Grizzly is used to perform a deterministic assessment of such a flaw propagation in a degraded reactor pressure vessel under pressurized thermal shock conditions. The stress intensity is calculated from J, and the toughness is computed using the fracture master curve and the degraded ductile to brittle transition temperature.

  5. Roadside bear viewing opportunities in Yellowstone National Park: characteristics, trends, and influence of whitebark pine

    Science.gov (United States)

    Haroldson, Mark A.; Gunther, Kerry

    2014-01-01

    Opportunities for viewing grizzly bears (Ursus arctos) and American black bears (U. americanus) from roadways in Yellowstone National Park (YNP) have increased in recent years. Unlike the panhandling bears common prior to the 1970s, current viewing usually involves bears feeding on natural foods. We define roadside bear viewing opportunities that cause traffic congestion as ‘‘bear-jams.’’ We investigated characteristics of bear-jams and their frequency relative to whitebark pine (Pinus albicaulis) cone production, an important fall food for bears, during 1990–2004. We observed a difference in diel distribution of bear-jams between species (x2=70.609, 4 df, Ptimes higher during poor cone crop years than good. We suggest that native foods found in road corridors may be especially important to some individual bears during years exhibiting poor whitebark pine crops. We discuss management implications of threats to whitebark pine and increasing habituation of bears to people.

  6. The importance of meat, particularly salmon, to body size, population productivity, and conservation of North American brown bears.

    Science.gov (United States)

    G.V. Hilderbrand; C.C. Schwartz; C.T. Robbins; M.E. Hanley Jacoby; S.M. Arthur; C. Servheen

    1999-01-01

    We hypothesized that the relative availability of meat, indicated by contribution to the diet, would be positively related to body size and population productivity of North American brown, or grizzly, bears (Ursus arctos). Dietary contributions of plant matter and meat derived from both terrestrial and marine sources were quantified by stable-...

  7. Visual sensing of fluoride ions by dipyrrolyl derivatives bearing electron-withdrawing groups

    Indian Academy of Sciences (India)

    Tamal Ghosh; Bhaskar G Maiya

    2004-01-01

    Two new, easy-to-prepare dipyrrolyl derivatives endowed with electron-withdrawing quinone or dicyano functionalities in their architecture permit the detection of fluoride ions under visual (naked-eye) as well as optical (absorption and fluorescence) and electrochemical conditions in organic solvents.

  8. Thrombin generation assay and transmission electron microscopy: a useful combination to study tissue factor-bearing microvesicles.

    Science.gov (United States)

    Gheldof, Damien; Hardij, Julie; Cecchet, Francesca; Chatelain, Bernard; Dogné, Jean-Michel; Mullier, François

    2013-01-01

    Patients with cancer have a 7- to 10-fold increased risk of developing venous thromboembolism. Circulating microvesicles could be a useful predictive biomarker for venous thromboembolism in cancer. Validated and standardised techniques that could be used to determine the complete microvesicle phenotype are required. These were two-fold: a) to characterise tissue factor (TF)-bearing microvesicles released by cultured breast cancer cells MDA-MB-231 by flow cytometry (FCM), transmission electron microscopy (TEM) and thrombin generation assay (TGA); and b) to validate the sensitivity and variability intra/inter-assay of TGA as a useful method to study the procoagulant activity (PCA) of microvesicles. Cultured breast cancer cells MDA-MB-231 were incubated for 45 minutes at 37°C. Samples were then centrifuged or not at 4,500 g for 15 minutes, and cells and MVs or MV-containing supernatants were used for TEM, FCM and TGA. In activity assays, microvesicles (i.e. cell-depleted supernatants) were incubated with anti-TF antibodies or with annexin V to assess the contribution of TF and phospholipids to the PCA. Alternatively, supernatants were filtered through 0.1, 0.22, 0.45 or 0.65 µm membranes and subjected to TGA. The majority of the PCA was associated with microvesicles smaller than 0.1 µm, and the mean microvesicle size estimated by TEM after 10,000 g centrifugation was 121±54 nm with a majority of vesicles between 100 and 200 nm. Microvesicles derived from 5,000 MDA-MB-231cells/ml were sufficient to significantly increase the thrombin generation of normal pooled plasma. TEM, FCM and filtration coupled to TGA represent a useful combination to study the PCA of TF-bearing microvesicles, whatever their size. And it will be interesting to implement these techniques in patients.

  9. Ortho effect in electron ionization mass spectrometry of N-acylanilines bearing a proximal halo substituent.

    Science.gov (United States)

    Jariwala, Freneil B; Figus, Margaret; Attygalle, Athula B

    2008-08-01

    Electron ionization (EI) mass spectra are not very helpful for characterizing ortho, meta, and para isomers of underivatized haloanilines since their spectra are virtually identical. In contrast, when the amino group of chloro-, bromo-, or iodoanilines is transformed to an N-formyl, N-acetyl, or N-benzoyl derivative, the spectra of the derivatives reveal a highly dramatic loss of a halogen radical, instead of an HX elimination usually expected from an "ortho effect." For example, the spectra of N-formyl, N-acetyl, and N-benzoyl derivatives of ortho isomers of chloro-, bromo-, and iodoanilines show a very prominent peak at m/z 120, 134, and 196, respectively, for the loss of the corresponding halogen atom.

  10. Reactor Pressure Vessel Integrity Assessments with the Grizzly Aging Simulation Code

    Energy Technology Data Exchange (ETDEWEB)

    Spencer, Benjamin; Backman, Marie; Hoffman, William; Chakraborty, Pritam

    2015-08-01

    Grizzly is a simulation tool being developed at Idaho National Laboratory (INL) as part of the US Department of Energy’s Light Water Reactor Sustainability program to provide improved safety assessments of systems, components, and structures in nuclear power plants subjected to age-related degradation. Its goal is to provide an improved scientific basis for decisions surrounding license renewal, which would permit operation of commercial nuclear power plants beyond 60 years. Grizzly is based on INL’s MOOSE framework, which enables multiphysics simulations in a parallel computing environment. It will address a wide variety of aging issues in nuclear power plant systems, components, and structures, modelling both the aging processes and the ability of age-degraded components to perform safely. The reactor pressure vessel (RPV) was chosen as the initial application for Grizzly. Grizzly solves tightly coupled equations of heat conduction and solid mechanics to simulate the global response of the RPV to accident conditions, and uses submodels to represent regions with pre-existing flaws. Domain integrals are used to calculate stress intensity factors on those flaws. A physically based empirical model is used to evaluate material embrittlement, and is used to evaluate whether crack growth would occur. Grizzly can represent the RPV in 2D or 3D, allowing it to evaluate effects that require higher dimensionality models to capture. Work is underway to use lower length scale models of material evolution to inform engineering models of embrittlement. This paper demonstrates an application of Grizzly to RPV failure assessment, and summarizes on-going work.

  11. Modeling multi-scale resource selection for bear rub trees in northwestern Montana

    Science.gov (United States)

    Morgan Henderson, Matthew J.; Hebblewhite, Mark; Mitchell, Michael S.; Stetz, Jeffrey B.; Kendall, Katherine C.; Carlson, Ross T.

    2015-01-01

    Both black (Ursus americanus) and grizzly bears (U. arctos) are known to rub on trees and other objects, producing a network of repeatedly used and identifiable rub sites. In 2012, we used a resource selection function to evaluate hypothesized relationships between locations of 887 bear rubs in northwestern Montana, USA, and elevation, slope angle, density of open roads and distance from areas of heightened plant-productivity likely containing forage for bears. Slope and density of open roads were negatively correlated with rub presence. No other covariates were supported as explanatory variables. We also hypothesized that bear rubs would be more strongly associated with closed roads and developed trails than with game trails. The frequencies of bear rubs on 30 paired segments of developed tracks and game trails were not different. Our results suggest bear rubs may be associated with bear travel routes, and support their use as “random” sampling devices for non-invasive spatial capture–recapture population monitoring.

  12. 75 FR 14496 - Endangered and Threatened Wildlife and Plants; Reinstatement of Protections for the Grizzly Bear...

    Science.gov (United States)

    2010-03-26

    ... Convention on International Trade of Endangered Species of Wild Fauna and Flora (CITES). List of Subjects in 50 CFR Part 17 Endangered and threatened species, Exports, Imports, Reporting and recordkeeping... reinstating the regulatory protections under the Endangered Species Act of 1973 (ESA), as amended, for......

  13. DNA Fingerprinting to monitor grizzly bear populations in the Greater Glacier Area

    Science.gov (United States)

    Kendall, Katherine; Dave, Schirokauer; Peterson, Kris; Waits, Lisette P.

    2001-01-01

    A study area of 8,100 km² (2 million acres) was established where 126 8 x 8 km (64 km²) grid cells were identified for placement of traps. Trapping was carried out during five 2- week trap sessions. Some 620 hair traps were placed in the field; samples were retrieved between May 19th and August 12th, 1998. Approximately 7,200 hair samples were collected that year. Hair was found at 80% of the traps where the average number of hair samples per trap site was 14. Forty percent of the samples had 5 or more hair follicles. Preliminary results of sampling indicate that DNA was extracted from 90-100% of the hair samples (N=300). Eight hundred miles of trail were surveyed between June 1 and October 9. Thirteen hundred hair samples were collected from rub trees along trails. Seven hundred scat samples were collected from trails.

  14. Use of isotopic sulfur to determine whitebark pine consumption by Yellowstone bears: a reassessment

    Science.gov (United States)

    Schwartz, Charles C.; Teisberg, Justin E.; Fortin, Jennifer K.; Haroldson, Mark A.; Servheen, Christopher; Robbins, Charles T.; van Manen, Frank T.

    2014-01-01

    Use of naturally occurring stable isotopes to estimate assimilated diet of bears is one of the single greatest breakthroughs in nutritional ecology during the past 20 years. Previous research in the Greater Yellowstone Ecosystem (GYE), USA, established a positive relationship between the stable isotope of sulfur (δ34S) and consumption of whitebark pine (Pinus albicaulis) seeds. That work combined a limited sample of hair, blood clots, and serum. Here we use a much larger sample to reassess those findings. We contrasted δ34S values in spring hair and serum with abundance of seeds of whitebark pine in samples collected from grizzly (Ursus arctos) and American black bears (U. americanus) in the GYE during 2000–2010. Although we found a positive relationship between δ34S values in spring hair and pine seed abundance for grizzly bears, the coefficients of determination were small (R2 ≤ 0.097); we failed to find a similar relationship with black bears. Values of δ34S in spring hair were larger in black bears and δ34S values in serum of grizzly bears were lowest in September and October, a time when we expect δ34S to peak if whitebark pine seeds were the sole source of high δ34S. The relationship between δ34S in bear tissue and the consumption of whitebark pine seeds, as originally reported, may not be as clean a method as proposed. Data we present here suggest other foods have high values of δ34S, and there is spatial heterogeneity affecting the δ34S values in whitebark pine, which must be addressed.

  15. Reactor Pressure Vessel Fracture Analysis Capabilities in Grizzly

    Energy Technology Data Exchange (ETDEWEB)

    Spencer, Benjamin [Idaho National Lab. (INL), Idaho Falls, ID (United States); Backman, Marie [Univ. of Tennessee, Knoxville, TN (United States); Chakraborty, Pritam [Idaho National Lab. (INL), Idaho Falls, ID (United States); Hoffman, William [Univ. of Idaho, Moscow, ID (United States)

    2015-03-01

    Efforts have been underway to develop fracture mechanics capabilities in the Grizzly code to enable it to be used to perform deterministic fracture assessments of degraded reactor pressure vessels (RPVs). Development in prior years has resulted a capability to calculate -integrals. For this application, these are used to calculate stress intensity factors for cracks to be used in deterministic linear elastic fracture mechanics (LEFM) assessments of fracture in degraded RPVs. The -integral can only be used to evaluate stress intensity factors for axis-aligned flaws because it can only be used to obtain the stress intensity factor for pure Mode I loading. Off-axis flaws will be subjected to mixed-mode loading. For this reason, work has continued to expand the set of fracture mechanics capabilities to permit it to evaluate off-axis flaws. This report documents the following work to enhance Grizzly’s engineering fracture mechanics capabilities for RPVs: • Interaction Integral and -stress: To obtain mixed-mode stress intensity factors, a capability to evaluate interaction integrals for 2D or 3D flaws has been developed. A -stress evaluation capability has been developed to evaluate the constraint at crack tips in 2D or 3D. Initial verification testing of these capabilities is documented here. • Benchmarking for axis-aligned flaws: Grizzly’s capabilities to evaluate stress intensity factors for axis-aligned flaws have been benchmarked against calculations for the same conditions in FAVOR. • Off-axis flaw demonstration: The newly-developed interaction integral capabilities are demon- strated in an application to calculate the mixed-mode stress intensity factors for off-axis flaws. • Other code enhancements: Other enhancements to the thermomechanics capabilities that relate to the solution of the engineering RPV fracture problem are documented here.

  16. Diet and Macronutrient Optimization in Wild Ursids: A Comparison of Grizzly Bears with Sympatric and Allopatric Black Bears

    National Research Council Canada - National Science Library

    Costello, Cecily M; Cain, Steven L; Pils, Shannon; Frattaroli, Leslie; Haroldson, Mark A; van Manen, Frank T

    2016-01-01

    ...% of digestible energy, relative to carbohydrates or lipids. In the wild, this ability is likely constrained by seasonal food availability, limits of intake rate as body size increases, and competition...

  17. Anatomical mercury speciation in bay scallops by thio-bearing chelating resin concentration and GC-electron capture detector determination.

    Science.gov (United States)

    Zhang, Qihua; Yang, Guipeng

    2014-01-01

    The highly toxic methyl-, ethyl- and phenylmercury species that may exist in the three main anatomical parts - the adductor muscle, the mantle and the visceral mass - of bay scallops (Argopecten irradias) were quantitatively released by cupric chloride, zinc acetate, sodium chloride and hydrochloric acid (HCl) under ultrasonic extraction. After centrifugation, the mercury species in the supernatant were concentrated by thio (SH)-bearing chelating resins, eluted with HClO4 and HCl and extracted with toluene. Separation was achieved by capillary GC equipped with programmed temperatures, a constant nitrogen flow and detected by a micro-electron capture detector (μECD). Under optimised conditions, the LODs for methyl-, ethyl- and phenylmercury in bay scallop samples were 1.1, 0.65 and 0.80 ng g(-1), respectively. The maximum RSD for three replicate determinations of methyl-, ethyl- and phenylmercury in bay scallop samples were 13.7%, 14.0% and 11.2%, respectively. In the concentration range of 4-200 ng g(-1) in bay scallop samples, the calibration graphs were linear with correlation coefficients not less than 0.997. Recoveries for spiked samples were in the range of 92.7-103.5% (methylmercury), 87.5-108.3% (ethylmercury) and 91.6-106.0% (phenylmercury), respectively. The method was verified by the determination of methylmercury in a CRM GBW10029 (Total Mercury and Methyl Mercury in Fish Tissue), with results in good agreement with the certified values. Methylmercury - the only existing species in bay scallops - was successfully determined by the method.

  18. Initial Probabilistic Evaluation of Reactor Pressure Vessel Fracture with Grizzly and Raven

    Energy Technology Data Exchange (ETDEWEB)

    Spencer, Benjamin [Idaho National Lab. (INL), Idaho Falls, ID (United States); Hoffman, William [Univ. of Idaho, Moscow, ID (United States); Sen, Sonat [Idaho National Lab. (INL), Idaho Falls, ID (United States); Rabiti, Cristian [Idaho National Lab. (INL), Idaho Falls, ID (United States); Dickson, Terry [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Bass, Richard [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-10-01

    The Grizzly code is being developed with the goal of creating a general tool that can be applied to study a variety of degradation mechanisms in nuclear power plant components. The first application of Grizzly has been to study fracture in embrittled reactor pressure vessels (RPVs). Grizzly can be used to model the thermal/mechanical response of an RPV under transient conditions that would be observed in a pressurized thermal shock (PTS) scenario. The global response of the vessel provides boundary conditions for local models of the material in the vicinity of a flaw. Fracture domain integrals are computed to obtain stress intensity factors, which can in turn be used to assess whether a fracture would initiate at a pre-existing flaw. These capabilities have been demonstrated previously. A typical RPV is likely to contain a large population of pre-existing flaws introduced during the manufacturing process. This flaw population is characterized stastistically through probability density functions of the flaw distributions. The use of probabilistic techniques is necessary to assess the likelihood of crack initiation during a transient event. This report documents initial work to perform probabilistic analysis of RPV fracture during a PTS event using a combination of the RAVEN risk analysis code and Grizzly. This work is limited in scope, considering only a single flaw with deterministic geometry, but with uncertainty introduced in the parameters that influence fracture toughness. These results are benchmarked against equivalent models run in the FAVOR code. When fully developed, the RAVEN/Grizzly methodology for modeling probabilistic fracture in RPVs will provide a general capability that can be used to consider a wider variety of vessel and flaw conditions that are difficult to consider with current tools. In addition, this will provide access to advanced probabilistic techniques provided by RAVEN, including adaptive sampling and parallelism, which can dramatically

  19. Functional and comparative study of lingual papillae in four species of bear (Ursidae) by scanning electron microscopy.

    Science.gov (United States)

    Pastor, J F; Barbosa, M; de Paz, F J; García, M; Ferrero, E

    2011-10-01

    The eight current species of bear (Ursidae) are widely distributed throughout Europe, Asia, and America. They are mainly encountered in the northern hemisphere, except for the spectacled bear and the sun bear, which are also found in the south of the equator. Adaptations of the masticatory apparatus (teeth, tongue, and musculature) to diet are one of the factors that imply the greatest structural changes in the cranium. This diet may be carnivorous, herbivorous, melliferous, or insectivorous, with one type of food predominating according to the time of year. The way in which food is eaten determines the morphology of the lingual surface; generally speaking, all bears put their mouth to the food, which, initially, they lick or they let the food stick to their tongue, as occurs when insects are eaten. As in all mammals, a distinction can be made between mechanical and gustatory papillae and the development and distribution of which depend on the species and their eating habits. In this study of the complete tongues of four species of adult bears, we describe the morphology of the lingual surfaces, the different types of papillae, their characteristics, and topographic distribution. It was seen that there were five main types of lingual papillae: filiform, conical, fungiform, foliate, and vallate. Morphology of the microgrooves and pores was similar to that observed in other mammals. In general, there were no great differences among the four species of bears studied, perhaps due to the similarity in the kind of food they consume in captivity.

  20. Investigation of synthesized Be-bearing silicate glass as laboratory reference sample at X-ray electron probe microanalysis of silicates

    Science.gov (United States)

    Belozerova, Olga Yu.; Mikhailov, Mikhail A.; Demina, Tamara V.

    2017-01-01

    The article discusses estimates of the stability and homogeneity in Be-Mg-Al-silicate glass produced by the authors and its applicability as a laboratory reference sample for X-ray electron probe microanalysis (EPMA) of Be-bearing silicate matters: crystals and quenching melt (glasses), silicates and oxides. The results were obtained using Superprobe-733 and Superprobe JXA-8200 (JEOL Ltd, Japan) devices. The sample homogeneity was studied on macro (10-100 μm) and micro (1-10 μm) levels and was evaluated by the scheme of dispersion analysis. The applicability of Be-bearing silicate glass as a reference sample for Mg, Al, Si determinations was tested on the international certified reference glasses and laboratory reference samples of minerals with a known composition. The obtained experimental metrological characteristics correspond to the "applied geochemistry" type of analysis (second category) and suggest that Be-bearing silicate glass is appropriate as a laboratory reference sample for EPMA of Be-bearing silicate matters, silicates and oxides. Using Be-Mg-Al-silicate glass as a reference sample we obtained satisfactory data on the composition of both some minerals including cordierite and beryllium cordierite, beryllium indialite, beryl and metastable phases (chrysoberyl, compounds with structure of β-quartz and petalite).

  1. The Grizzly Lake complex (Yellowstone Volcano, USA): Mixing between basalt and rhyolite unraveled by microanalysis and X-ray microtomography

    Science.gov (United States)

    Morgavi, Daniele; Arzilli, Fabio; Pritchard, Chad; Perugini, Diego; Mancini, Lucia; Larson, Peter; Dingwell, Donald B.

    2016-09-01

    Magma mixing is a widespread petrogenetic process. It has long been suspected to operate in concert with fractional crystallization and assimilation to produce chemical and temperature gradients in magmas. In particular, the injection of mafic magmas into felsic magma chambers is widely regarded as a key driver in the sudden triggering of what often become highly explosive volcanic eruptions. Understanding the mechanistic event chain leading to such hazardous events is a scientific goal of high priority. Here we investigate a mingling event via the evidence preserved in mingled lavas using a combination of X-ray computed microtomographic and electron microprobe analyses, to unravel the complex textures and attendant chemical heterogeneities of the mixed basaltic and rhyolitic eruption of Grizzly Lake in the Norris-Mammoth corridor of the Yellowstone Plateau volcanic field (YVF). We observe evidence that both magmatic viscous inter-fingering of magmas and disequilibrium crystallization/dissolution processes occur. Furthermore, these processes constrain the timescale of interaction between the two magmatic components prior to their eruption. X-ray microtomography images show variegated textural features, involving vesicle and crystal distributions, filament morphology, the distribution of enclaves, and further textural features otherwise obscured in conventional 2D observations and analyses. Although our central effort was applied to the determination of mixing end members, analysis of the hybrid portion has led to the discovery that mixing in the Grizzly Lake system was also characterized by the disintegration and dissolution of mafic crystals in the rhyolitic magma. The presence of mineral phases in both end member, for example, forsteritic olivine, sanidine, and quartz and their transport throughout the magmatic mass, by a combination of both mixing dynamics and flow imposed by ascent of the magmatic mass and its eruption, might have acted as a "geometric

  2. Journal bearing

    Science.gov (United States)

    Menke, John R.; Boeker, Gilbert F.

    1976-05-11

    1. An improved journal bearing comprising in combination a non-rotatable cylindrical bearing member having a first bearing surface, a rotatable cylindrical bearing member having a confronting second bearing surface having a plurality of bearing elements, a source of lubricant adjacent said bearing elements for supplying lubricant thereto, each bearing element consisting of a pair of elongated relatively shallowly depressed surfaces lying in a cylindrical surface co-axial with the non-depressed surface and diverging from one another in the direction of rotation and obliquely arranged with respect to the axis of rotation of said rotatable member to cause a flow of lubricant longitudinally along said depressed surfaces from their distal ends toward their proximal ends as said bearing members are rotated relative to one another, each depressed surface subtending a radial angle of less than 360.degree., and means for rotating said rotatable bearing member to cause the lubricant to flow across and along said depressed surfaces, the flow of lubricant being impeded by the non-depressed portions of said second bearing surface to cause an increase in the lubricant pressure.

  3. Magnetic bearings grow more attractive

    Science.gov (United States)

    1993-10-01

    Advances in materials and electronics have enabled designers to devise simpler, smaller magnetic bearings. As a result, costs have dropped, widening the applications for these very-low-friction devices. Avcon (Advanced Controls Technology) has patented a permanent-magnet bias actively controlled bearing. Here high-energy rare earth permanent-magnet materials supply the basic bearing load levitation, while servo-driven electromagnets generate stabilization and centering forces for motion contol. Previous heavy-duty magnetic bearings used electromagnets entirely for suspension and control, which led to large bearings and control systems with higher power requirements. Avcon has developed several types of permanent-magnet bias bearings. The simplest is the radial repulsion bearing. Avcon's homopolar permanent-magnet bias active bearing is the most versatile of the company's designs.

  4. Gene flow between insular, coastal and interior populations of brown bears in Alaska.

    Science.gov (United States)

    Paetkau, D; Shields, G F; Strobeck, C

    1998-10-01

    The brown bears of coastal Alaska have been recently regarded as comprising from one to three distinct genetic groups. We sampled brown bears from each of the regions for which hypotheses of genetic uniqueness have been made, including the bears of the Kodiak Archipelago and the bears of Admiralty, Baranof and Chichagof (ABC) Islands in southeast Alaska. These samples were analysed with a suite of nuclear microsatellite markers. The 'big brown bears' of coastal Alaska were found to be part of the continuous continental distribution of brown bears, and not genetically isolated from the physically smaller 'grizzly bears' of the interior. By contrast, Kodiak brown bears appear to have experienced little or no genetic exchange with continental populations in recent generations. The bears of the ABC Islands, which have previously been shown to undergo little or no female-mediated gene flow with mainland populations, were found not to be genetically isolated from mainland bears. The data from the four insular populations indicate that female and male dispersal can be reduced or eliminated by water barriers of 2-4 km and 7 km in width, respectively.

  5. Fracture Capabilities in Grizzly with the extended Finite Element Method (X-FEM)

    Energy Technology Data Exchange (ETDEWEB)

    Dolbow, John [Idaho National Lab. (INL), Idaho Falls, ID (United States); Zhang, Ziyu [Idaho National Lab. (INL), Idaho Falls, ID (United States); Spencer, Benjamin [Idaho National Lab. (INL), Idaho Falls, ID (United States); Jiang, Wen [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-09-01

    Efforts are underway to develop fracture mechanics capabilities in the Grizzly code to enable it to be used to perform deterministic fracture assessments of degraded reactor pressure vessels (RPVs). A capability was previously developed to calculate three-dimensional interaction- integrals to extract mixed-mode stress-intensity factors. This capability requires the use of a finite element mesh that conforms to the crack geometry. The eXtended Finite Element Method (X-FEM) provides a means to represent a crack geometry without explicitly fitting the finite element mesh to it. This is effected by enhancing the element kinematics to represent jump discontinuities at arbitrary locations inside of the element, as well as the incorporation of asymptotic near-tip fields to better capture crack singularities. In this work, use of only the discontinuous enrichment functions was examined to see how accurate stress intensity factors could still be calculated. This report documents the following work to enhance Grizzly’s engineering fracture capabilities by introducing arbitrary jump discontinuities for prescribed crack geometries; X-FEM Mesh Cutting in 3D: to enhance the kinematics of elements that are intersected by arbitrary crack geometries, a mesh cutting algorithm was implemented in Grizzly. The algorithm introduces new virtual nodes and creates partial elements, and then creates a new mesh connectivity; Interaction Integral Modifications: the existing code for evaluating the interaction integral in Grizzly was based on the assumption of a mesh that was fitted to the crack geometry. Modifications were made to allow for the possibility of a crack front that passes arbitrarily through the mesh; and Benchmarking for 3D Fracture: the new capabilities were benchmarked against mixed-mode three-dimensional fracture problems with known analytical solutions.

  6. Magnetic Bearing

    Science.gov (United States)

    1996-01-01

    AVCON, Inc. produces advanced magnetic bearing systems for industrial use, offering a unique technological approach based on contract work done at Marshall Space Flight Center and Lewis Research Center. Designed for the turbopump of the Space Shuttle main engine, they are now used in applications such as electric power generation, petroleum refining, machine tool operation and natural gas pipelines. Magnetic bearings support moving machinery without physical contact; AVCON's homopolar approach is a hybrid of permanent and electromagnets which are one-third the weight, smaller and more power- efficient than previous magnetic bearings.

  7. Foil bearings

    Science.gov (United States)

    Elrod, David A.

    1993-01-01

    The rolling element bearings (REB's) which support many turbomachinery rotors offer high load capacity, low power requirements, and durability. Two disadvantages of REB's are: (1) rolling or sliding contact within the bearing has life-limiting consequences; and (2) REB's provide essentially no damping. The REB's in the Space Shuttle Main Engine (SSME) turbopumps must sustain high static and dynamic loads, at high speeds, with a cryogenic fluid as lubricant and coolant. The pump end ball bearings limit the life of the SSME high pressure oxygen turbopump (HPOTP). Compliant foil bearing (CFB) manufacturers have proposed replacing turbopump REB's with CFB's CFB's work well in aircraft air cycle machines, auxiliary power units, and refrigeration compressors. In a CFB, the rotor only contracts the foil support structure during start up and shut down. CFB damping is higher than REB damping. However, the load capacity of the CFB is low, compared to a REB. Furthermore, little stiffness and damping data exists for the CFB. A rotordynamic analysis for turbomachinery critical speeds and stability requires the input of bearing stiffness and damping coefficients. The two basic types of CFB are the tension-dominated bearing and the bending-dominated bearing. Many investigators have analyzed and measured characteristics of tension-dominated foil bearings, which are applied principally in magnetic tape recording. The bending-dominated CFB is used more in rotating machinery. This report describes the first phase of a structural analysis of a bending-dominated, multileaf CFB. A brief discussion of CFB literature is followed by a description and results of the present analysis.

  8. Foil bearings

    Science.gov (United States)

    Elrod, David A.

    1993-11-01

    The rolling element bearings (REB's) which support many turbomachinery rotors offer high load capacity, low power requirements, and durability. Two disadvantages of REB's are: (1) rolling or sliding contact within the bearing has life-limiting consequences; and (2) REB's provide essentially no damping. The REB's in the Space Shuttle Main Engine (SSME) turbopumps must sustain high static and dynamic loads, at high speeds, with a cryogenic fluid as lubricant and coolant. The pump end ball bearings limit the life of the SSME high pressure oxygen turbopump (HPOTP). Compliant foil bearing (CFB) manufacturers have proposed replacing turbopump REB's with CFB's CFB's work well in aircraft air cycle machines, auxiliary power units, and refrigeration compressors. In a CFB, the rotor only contracts the foil support structure during start up and shut down. CFB damping is higher than REB damping. However, the load capacity of the CFB is low, compared to a REB. Furthermore, little stiffness and damping data exists for the CFB. A rotordynamic analysis for turbomachinery critical speeds and stability requires the input of bearing stiffness and damping coefficients. The two basic types of CFB are the tension-dominated bearing and the bending-dominated bearing. Many investigators have analyzed and measured characteristics of tension-dominated foil bearings, which are applied principally in magnetic tape recording. The bending-dominated CFB is used more in rotating machinery. This report describes the first phase of a structural analysis of a bending-dominated, multileaf CFB. A brief discussion of CFB literature is followed by a description and results of the present analysis.

  9. Electron spin resonance (ESR) dating of hominid-bearing deposits in the Caverna delle Fate, Ligure, Italy

    Science.gov (United States)

    Falgueres, Christophe; Yokoyama, Yuji; Bibron, Roland

    1990-07-01

    Stalagmitic floors interstratified with Mousterian deposits from the Caverna delle Fate (Italy) have been dated by the electron spin resonance (ESR) method. Three samples dated fall between 60,000 and 74,000 yr and indicate the age of the Mousterian deposits. They are in good agreement with ages determined by nondestructive γ-ray spectrometry of the human remains from 231Pa/ 235U and 230Th /234U ratios, which are, respectively, 75,000 -14,000+21,000 and 82,000 -25,000+36,000 yr. These dates are consistent with the morphological characteristics of the bones as Neanderthal remains.

  10. Advanced Identification and Quantification of In-Bearing Minerals by Scanning Electron Microscope-Based Image Analysis.

    Science.gov (United States)

    Bachmann, Kai; Frenzel, Max; Krause, Joachim; Gutzmer, Jens

    2017-06-01

    The identification and accurate characterization of discrete grains of rare minerals in sulfide base-metal ores is usually a cumbersome procedure due to the small grain sizes (typically mineral assemblages in the material. In this article, a new strategy for finding and identifying indium minerals, and quantifying their composition and abundance is presented, making use of mineral liberation analysis (MLA) and electron probe microanalysis (EPMA). The method was successfully applied to polymetallic massive sulfide ores from the Neves-Corvo deposit in Portugal. The presence of roquesite and sakuraiite could be systematically detected, their concentration quantified by MLA measurements, and their identity later confirmed by EPMA analyses. Based on these results, an almost complete indium deportment could be obtained for the studied samples. This validates the approach taken, combining automated mineralogy data with electron microprobe analysis. A similar approach could be used to find minerals of other common minor and trace elements in complex base-metal sulfide ores, for example Se, Ge, Sb, or Ag, thus permitting the targeted development of resource technologies suitable for by-product recovery.

  11. Hydrodynamic bearings

    CERN Document Server

    Bonneau, Dominique; Souchet, Dominique

    2014-01-01

    This Series provides the necessary elements to the development and validation of numerical prediction models for hydrodynamic bearings. This book describes the rheological models and the equations of lubrication. It also presents the numerical approaches used to solve the above equations by finite differences, finite volumes and finite elements methods.

  12. Monitoring and mitigating measures to reduce potential impacts of oil and gas exploration and development on bears in the Inuvik region

    Energy Technology Data Exchange (ETDEWEB)

    Branigan, M. [Government of the Northwest Territories, Inuvik, NT (Canada). Dept. of Environment and Natural Resources

    2007-07-01

    The Inuvik Region consists of the Northwest Territories portion of the Inuvialuit Settlement Region and the Gwich'in Settlement Area. The range of grizzly bears, polar bears and black bears extends to different parts of the region. The potential impact of development depends on the season of the development and the species of bear found in the footprint. As such, monitoring and mitigation measures should take this into consideration. This presentation focused on the potential impacts and current practices to monitor and mitigate the impacts in the region. Mitigation measures currently used include: communication with stakeholders; waste management guidelines; use of wildlife monitors to identify key habitat and den sites and to deter bears; minimum flight altitudes; and safety training. Suggestions for additional mitigation measures were also presented. figs.

  13. Synthesis, Properties, and Light-Emitting Electrochemical Cell (LEEC) Device Fabrication of Cationic Ir(III) Complexes Bearing Electron-Withdrawing Groups on the Cyclometallating Ligands.

    Science.gov (United States)

    Pal, Amlan K; Cordes, David B; Slawin, Alexandra M Z; Momblona, Cristina; Ortı, Enrique; Samuel, Ifor D W; Bolink, Henk J; Zysman-Colman, Eli

    2016-10-17

    The structure-property relationship study of a series of cationic Ir(III) complexes in the form of [Ir(C^N)2(dtBubpy)]PF6 [where dtBubpy = 4,4'-di-tert-butyl-2,2'-bipyridine and C^N = cyclometallating ligand bearing an electron-withdrawing group (EWG) at C4 of the phenyl substituent, i.e., -CF3 (1), -OCF3 (2), -SCF3 (3), -SO2CF3 (4)] has been investigated. The physical and optoelectronic properties of the four complexes were comprehensively characterized, including by X-ray diffraction analysis. All the complexes exhibit quasireversible dtBubpy-based reductions from -1.29 to -1.34 V (vs SCE). The oxidation processes are likewise quasireversible (metal + C^N ligand) and are between 1.54 and 1.72 V (vs SCE). The relative oxidation potentials follow a general trend associated with the Hammett parameter (σ) of the EWGs. Surprisingly, complex 4 bearing the strongest EWG does not adhere to the expected Hammett behavior and was found to exhibit red-shifted absorption and emission maxima. Nevertheless, the concept of introducing EWGs was found to be generally useful in blue-shifting the emission maxima of the complexes (λem = 484-545 nm) compared to that of the prototype complex [Ir(ppy)2(dtBubpy)]PF6 (where ppy = 2-phenylpyridinato) (λem = 591 nm). The complexes were found to be bright emitters in solution at room temperature (ΦPL = 45-66%) with microsecond excited-state lifetimes (τe = 1.14-4.28 μs). The photophysical properties along with density functional theory (DFT) calculations suggest that the emission of these complexes originates from mixed contributions from ligand-centered (LC) transitions and mixed metal-to-ligand and ligand-to-ligand charge transfer (LLCT/MLCT) transitions, depending on the EWG. In complexes 1, 3, and 4 the (3)LC character is prominent over the mixed (3)CT character, while in complex 2, the mixed (3)CT character is much more pronounced, as demonstrated by DFT calculations and the observed positive solvatochromism effect. Due to the

  14. Light Water Reactor Sustainability Program Grizzly Year-End Progress Report

    Energy Technology Data Exchange (ETDEWEB)

    Benjamin Spencer; Yongfeng Zhang; Pritam Chakraborty; S. Bulent Biner; Marie Backman; Brian Wirth; Stephen Novascone; Jason Hales

    2013-09-01

    The Grizzly software application is being developed under the Light Water Reactor Sustainability (LWRS) program to address aging and material degradation issues that could potentially become an obstacle to life extension of nuclear power plants beyond 60 years of operation. Grizzly is based on INL’s MOOSE multiphysics simulation environment, and can simultaneously solve a variety of tightly coupled physics equations, and is thus a very powerful and flexible tool with a wide range of potential applications. Grizzly, the development of which was begun during fiscal year (FY) 2012, is intended to address degradation in a variety of critical structures. The reactor pressure vessel (RPV) was chosen for an initial application of this software. Because it fulfills the critical roles of housing the reactor core and providing a barrier to the release of coolant, the RPV is clearly one of the most safety-critical components of a nuclear power plant. In addition, because of its cost, size and location in the plant, replacement of this component would be prohibitively expensive, so failure of the RPV to meet acceptance criteria would likely result in the shutting down of a nuclear power plant. The current practice used to perform engineering evaluations of the susceptibility of RPVs to fracture is to use the ASME Master Fracture Toughness Curve (ASME Code Case N-631 Section III). This is used in conjunction with empirically based models that describe the evolution of this curve due to embrittlement in terms of a transition temperature shift. These models are based on an extensive database of surveillance coupons that have been irradiated in operating nuclear power plants, but this data is limited to the lifetime of the current reactor fleet. This is an important limitation when considering life extension beyond 60 years. The currently available data cannot be extrapolated with confidence further out in time because there is a potential for additional damage mechanisms (i

  15. Photophysical Properties and Electronic Structure of Porphyrins Bearing Zero to Four meso-Phenyl Substituents: New Insights into Seemingly Well Understood Tetrapyrroles.

    Science.gov (United States)

    Mandal, Amit Kumar; Taniguchi, Masahiko; Diers, James R; Niedzwiedzki, Dariusz M; Kirmaier, Christine; Lindsey, Jonathan S; Bocian, David F; Holten, Dewey

    2016-12-15

    Six free base porphyrins bearing 0-4 meso substituents have been examined by steady-state and time-resolved absorption and fluorescence spectroscopy in both toluene and N,N-dimethylformamide (DMF). The lifetime of the lowest singlet excited state (S1) decreases with an increase in the number of meso-phenyl groups; the values in toluene are H2P-0 (15.5 ns) > H2P-1 (14.9 ns) > H2P-2c (14.4 ns) > H2P-2t (13.8 ns) ∼ H2P-3 (13.8 ns) > H2P-4 (12.8 ns), where "H2P" refers to the core free base porphyrin, the numerical suffix indicates the number of meso-phenyl groups, and "c" and "t" refer to cis and trans, respectively. The opposite trend is found for the fluorescence quantum yield; the values in toluene are H2P-0 (0.049) radiative and nonradiative (internal conversion and intersystem crossing) rate constants for S1 decay increase with the increasing number of meso-phenyl groups. The increase in the rate constant for fluorescence parallels an increase in oscillator strength of the S0 → S1 absorption manifold. The trend is reproduced by time-dependent density functional theory calculations. The calculations within the context of the four-orbital model reveal that the enhanced S0 ↔ S1 radiative probabilities derive from a preferential effect of the meso-phenyl groups to raise the energy of the highest occupied molecular orbital, which underpins a parallel bathochromic shift in the S0 → S1 absorption wavelength. Polarizations of the S1 and S2 excited states with respect to molecular structural features (e.g., the central proton axis) are analyzed in the context of historical conventions for porphyrins versus chlorins and bacteriochlorins, where some ambiguity exists, including for porphine, one of the simplest tetrapyrroles. Collectively, the study affords fundamental insights into the photophysical properties and electronic structure of meso-phenylporphyrins that should aid their continued widespread use as benchmarks for tetrapyrrole-based architectures in

  16. Microstructure, mechanical, and thermal properties of the Sn-1Ag-0.5Cu solder alloy bearing Fe for electronics applications

    Energy Technology Data Exchange (ETDEWEB)

    Shnawah, Dhafer Abdul-Ameer, E-mail: dhafer_eng@yahoo.com [Department of Mechanical Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia); Said, Suhana Binti Mohd [Department of Electrical Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia); Sabri, Mohd Faizul Mohd; Badruddin, Irfan Anjum [Department of Mechanical Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia); Che Faxing [Institute of Microelectronics, A-STAR (Agency for Science, Technology and Research), 11 Science Park Road, Singapore Science Park II, Singapore 117685 (Singapore)

    2012-08-15

    This work investigates the effect of Fe addition on the microstructural, mechanical, and thermal properties of the Sn-1Ag-0.5Cu (SAC105) solder alloy. The addition of Fe leads to the formation of large circular FeSn{sub 2} intermetallic compound (IMC) particles, which produce a weak interface with the {beta}-Sn matrix. The addition of Fe also leads to the inclusion of Fe in the Ag{sub 3}Sn and Cu{sub 6}Sn{sub 5} IMC particles. Moreover, Fe-bearing solders have been shown to form large primary {beta}-Sn grains. The weak interface between the large FeSn{sub 2} IMC particles and the {beta}-Sn matrix together with the presence of the large primary {beta}-Sn grains results in a significant reduction on the elastic modulus and yield strength of the Fe-bearing solders. Moreover, the improved plasticity of the large primary {beta}-Sn grains causes the Fe-bearing solders to exhibit large total elongation. The addition of Fe also significantly reduces the effect of aging. After aging at 100 Degree-Sign C and 180 Degree-Sign C, it has been observed that the Fe-bearing solders significantly suppress the coarsening of the Ag{sub 3}Sn IMC particles; consequently, they exhibit stable mechanical properties. This effect can be attributed to the inclusion of Fe in the Ag{sub 3}Sn IMC particles. In addition, fracture surface analysis indicates that the addition of Fe to the SAC105 solder alloy does not affect the mode of fracture, and all tested solders exhibited large ductile-dimples on the fracture surface. Moreover, the addition of Fe did not produce any significant effect on the melting behavior. As a result, the use conditions of the Fe-bearing solders are consistent with the conditions for conventional Sn-Ag-Cu solder alloys.

  17. Comparative analysis of fecal microbiota and intestinal microbial metabolic activity in captive polar bears.

    Science.gov (United States)

    Schwab, Clarissa; Gänzle, Michael

    2011-03-01

    The composition of the intestinal microbiota depends on gut physiology and diet. Ursidae possess a simple gastrointestinal system composed of a stomach, small intestine, and indistinct hindgut. This study determined the composition and stability of fecal microbiota of 3 captive polar bears by group-specific quantitative PCR and PCR-DGGE (denaturing gradient gel electrophoresis) using the 16S rRNA gene as target. Intestinal metabolic activity was determined by analysis of short-chain fatty acids in feces. For comparison, other Carnivora and mammals were included in this study. Total bacterial abundance was approximately log 8.5 DNA gene copies·(g feces)-1 in all 3 polar bears. Fecal polar bear microbiota was dominated by the facultative anaerobes Enterobacteriaceae and enterococci, and the Clostridium cluster I. The detection of the Clostridium perfringens α-toxin gene verified the presence of C. perfringens. Composition of the fecal bacterial population was stable on a genus level; according to results obtained by PCR-DGGE, dominant bacterial species fluctuated. The total short-chain fatty acid content of Carnivora and other mammals analysed was comparable; lactate was detected in feces of all carnivora but present only in trace amounts in other mammals. In comparison, the fecal microbiota and metabolic activity of captive polar bears mostly resembled the closely related grizzly and black bears.

  18. Eco-Heroes out of Place and Relations: Decolonizing the Narratives of "Into the Wild" and "Grizzly Man" through Land Education

    Science.gov (United States)

    Korteweg, Lisa; Oakley, Jan

    2014-01-01

    Eco-heroic quests for environmental communion continue to be represented, mediated, and glorified through film and media narratives. This paper examines two eco-heroic quests in the Alaskan "wilderness" that have been portrayed in two Hollywood motion pictures: the movies "Grizzly Man" and "Into the Wild". Both films…

  19. Contributions of vital rates to growth of a protected population of American black bears

    Science.gov (United States)

    Mitchell, M.S.; Pacifici, L.B.; Grand, J.B.; Powell, R.A.

    2009-01-01

    Analyses of large, long-lived animals suggest that adult survival generally has the potential to contribute more than reproduction to population growth rate (??), but because survival varies little, high variability in reproduction can have a greater influence. This pattern has been documented for several species of large mammals, but few studies have evaluated such contributions of vital rates to ?? for American black bears (Ursus americanus). We used variance-based perturbation analyses (life table response experiments, LTRE) and analytical sensitivity and elasticity analyses to examine the actual and potential contributions of variation of vital rates to variation in growth rate (??) of a population of black bears inhabiting the Pisgah Bear Sanctuary in the southern Appalachian Mountains of North Carolina, using a 22-year dataset. We found that recruitment varied more than other vital rates; LTRE analyses conducted over several time intervals thus indicated that recruitment generally contributed at least as much as juvenile and adult survival to observed variation in ??, even though the latter 2 vital rates had the greater potential to affect ??. Our findings are consistent with predictions from studies on polar bears (U. maritimus) and grizzly bears (U. arctos), but contrast with the few existing studies on black bears in ways that suggest levels of protection from human-caused mortality might explain whether adult survival or recruitment contribute most to variation in ?? for this species. We hypothesize that ?? is most strongly influenced by recruitment in protected populations where adult survival is relatively high and constant, whereas adult survival will most influence ?? for unprotected populations. ?? 2009 International Association for Bear Research and Management.

  20. Axial Halbach Magnetic Bearings

    Science.gov (United States)

    Eichenberg, Dennis J.; Gallo, Christopher A.; Thompson, William K.

    2008-01-01

    Axial Halbach magnetic bearings have been investigated as part of an effort to develop increasingly reliable noncontact bearings for future high-speed rotary machines that may be used in such applications as aircraft, industrial, and land-vehicle power systems and in some medical and scientific instrumentation systems. Axial Halbach magnetic bearings are passive in the sense that unlike most other magnetic bearings that have been developed in recent years, they effect stable magnetic levitation without need for complex active control.

  1. Electronic State of Sodium trans-[Tetrachloridobis(1H-indazole)ruthenate(III)] (NKP-1339) in Tumor, Liver and Kidney Tissue of a SW480-bearing Mouse

    Science.gov (United States)

    Blazevic, Amir; Hummer, Alfred A.; Heffeter, Petra; Berger, Walter; Filipits, Martin; Cibin, Giannantonio; Keppler, Bernhard K.; Rompel, Annette

    2017-01-01

    Ruthenium complexes are promising candidates for anticancer agents, especially NKP-1339 (sodium trans-[tetrachloridobis(1H-indazole)ruthenate(III)]), which is on the edge to clinical applications. The anticancer mechanism seems to be tightly linked to the redox chemistry but despite progress in human clinical trials the in vivo Ru oxidation state and the coordination of Ru remains unclear. The Ru-based anticancer drug NKP-1339 was studied applying XANES (Cl K- and Ru L2,3-edges) in tumor, kidney and liver tissue of a SW480 bearing mouse. Based on coordination charge and 3D XANES plots containing a series of model compounds as well as pre-edge analysis of the ligand Cl K-edge it is suggested that NKP-1339 remains in its +III oxidation state after 24 hours and at least one of the four chlorido ligands remain covalently bound to the Ru ion showing a biotransformation from RuIIIN2Cl4 to RuIIIClx(N/O)6‑x (X = 1 or 2).

  2. Cryogenic Hybrid Magnetic Bearing

    Science.gov (United States)

    Meeks, Crawford R.; Dirusso, Eliseo; Brown, Gerald V.

    1994-01-01

    Cryogenic hybrid magnetic bearing is example of class of magnetic bearings in which permanent magnets and electromagnets used to suspend shafts. Electromagnets provide active control of position of shaft. Bearing operates at temperatures from -320 degrees F (-196 degrees C) to 650 degrees F (343 degrees C); designed for possible use in rocket-engine turbopumps, where effects of cryogenic environment and fluid severely limit lubrication of conventional ball bearings. This and similar bearings also suitable for terrestrial rotating machinery; for example, gas-turbine engines, high-vacuum pumps, canned pumps, precise gimbals that suspend sensors, and pumps that handle corrosive or gritty fluids.

  3. TOPICAL REVIEW: Superconducting bearings

    Science.gov (United States)

    Hull, John R.

    2000-02-01

    The physics and technology of superconducting bearings is reviewed. Particular attention is given to the use of high-temperature superconductors (HTSs) in rotating bearings. The basic phenomenology of levitational forces is presented, followed by a brief discussion of the theoretical models that can be used for conceptual understanding and calculations. The merits of various HTS bearing designs are presented, and the behaviour of HTS bearings in typical situations is discussed. The article concludes with a brief survey of various proposed applications for HTS bearings.

  4. Good neighbours: even bears kept happy by the new approach to wilderness project

    Energy Technology Data Exchange (ETDEWEB)

    Stonehouse, D.

    2000-04-01

    Experiences gained by Husky Oil and Rigel Energy drilling a successful exploratory well in Kananaskis country, Calgary's wilderness playground, are described. 'Fitting in' with the character of 'K-country' entailed developing a plan acceptable to recreational users, aboriginal groups, government agencies, and environmentalists. The result was a landmark effort in industrial adaptation to nature: the Eastern Slope Grizzly Bear Project, a major cumulative effects assessment, which is now gaining acceptance as an industry model. The assessment involved surveying the distribution of deer, elk, moose, sheep, rare plants, breeding birds and fish species and the tracking and mapping of the movements of bears, to get a complete picture of the health of the eastern slope habitat, and to provide the foundation for assessing development and land use. The study showed Husky Oil how to proceed without doing environmental damage. It influenced the manner in which the field was delineated, it altered production tests, it forced reinjection of fluids and gas during well testing rather than hauling it away in trucks, it determined the type and route for the access road and later the location of the pipeline, all in an effort to stay clear of high quality ungulate and bear habitat. It was time consuming and expensive, but according to company officials, well worth it. Development was also influenced by traditional land use and preservation of native cultural resources; for example, the pipeline was rerouted to avoid archaeological sites.

  5. Teddy Bear Stories

    DEFF Research Database (Denmark)

    van Leeuwen, Theo; Caldas-Coulthardt, Carmen

    2014-01-01

    This paper presents a semiotic analysis of a key cultural artefact, the teddy bear. After introducing the iconography of the teddy bear, it analyses different kinds of stories to show how teddy bears are endowed with meaning in everyday life: stories from children's books, reminiscenses by adults...... about their childhood teddy bears, and children's accounts of what they do with teddy bears, both written for school and told 'out of school', The chapter sees teddy bears as artefacts that provide a cultural channeling for the child's need of a transitional object and argues that the meanings of teddy...... bears have traditionally centred on interpersonal relations within the nuclear family, but have recently been institutionalized and commercialized....

  6. EcoBears

    DEFF Research Database (Denmark)

    Nielsen, Nick; Pedersen, Sandra Bleuenn; Sørensen, Jens Ager

    2015-01-01

    In this paper, we introduce the EcoBears concept that aims to augment household appliances with functional and aesthetic features to promote their "use'' and "longevity of use'' to prevent their disposal. The EcoBears also aim to support the communication of environmental issues in the home setting....... We present our initial design and implementation of the EcoBears that consist of two bear modules (a mother and her cub). We also present our preliminary concept validations and lessons learned to be considered for future directions....

  7. Nature of the lowest electron transitions in styryl bases benzothiazole derivatives and analogues bearing para-methoxy and -trifluoromethyl substituents in phenylyne moiety

    Science.gov (United States)

    Navozenko, O. M.; Naumenko, A. P.; Yashchuk, V. M.; Bricks, J. L.; Slominskii, Yu. L.; Ryabitskii, A. B.; Kachkovsky, O. D.

    2016-06-01

    Combined quantum-chemical and spectral investigation of cyanine bases derivatives of thiastyryls as well as their analogues with dimethylamino, metoxy and trifluorine-methyl substituents has been fulfilled. The calculations have shown that going from cationic styryl/metoxystyryl to the corresponding neutral bases is accompanied by substantial change of the equilibrium molecular geometry and charge distribution at atoms, while the experimental absorption band undergoes the essential hypsochromic shift. It is established that introducing on the donor groups in the bases causes negligible change of the carbon-carbon bond and atomic charges in the main chromophore, in contrast to the substantial changes of the magnitude and direction state dipole moments in both ground and excited states. It is found that the bases with the donor groups in benzthiazole moiety and with acceptor CF3 substituent demonstrate the inversion of the direction of the dipole moment. Based on the spectral and quantum-chemical study, one has proposed that some widening of the spectral bands is connected with the vibronic interaction, not with the second electron transition.

  8. Damper bearing rotordynamics

    Science.gov (United States)

    Elrod, David A.

    1990-01-01

    High side loads reduce the life of the Space Shuttle Main Engine (SSME) High Pressure Oxygen Turbopump (HPOTP) bearings. High stiffness damper seals were recommended to reduce the loads on the pump and turbine end bearings in the HPOTP. The seals designed for use on the pump end are expected to adequately reduce the bearing loads; the predicted performance of the planned turbine end seal is marginal. An alternative to the suggested turbine end seal design is a damper bearing with radial holes from the pressurized center of the turbopump rotor, feeding a smooth land region between two rough-stator/smooth-rotor annular seals. An analysis was prepared to predict the leakage and rotor dynamic coefficients (stiffness, damping, and added mass) of the damper bearing. Governing equations of the seal analysis modified to model the damper bearing; differences between the upstream conditions of the damper bearing and a typical annular seal; prediction of the damper bearing analysis; and assumptions of the analysis which require further investigation are described.

  9. Touchdown Ball-Bearing System for Magnetic Bearings

    Science.gov (United States)

    Kingsbury, Edward P.; Price, Robert; Gelotte, Erik; Singer, Herbert B.

    2003-01-01

    The torque-limited touchdown bearing system (TLTBS) is a backup mechanical-bearing system for a high-speed rotary machine in which the rotor shaft is supported by magnetic bearings in steady-state normal operation. The TLTBS provides ball-bearing support to augment or supplant the magnetic bearings during startup, shutdown, or failure of the magnetic bearings. The TLTBS also provides support in the presence of conditions (in particular, rotational acceleration) that make it difficult or impossible to control the magnetic bearings or in which the magnetic bearings are not strong enough (e.g., when the side load against the rotor exceeds the available lateral magnetic force).

  10. Ultra-precision bearings

    CERN Document Server

    Wardle, F

    2015-01-01

    Ultra-precision bearings can achieve extreme accuracy of rotation, making them ideal for use in numerous applications across a variety of fields, including hard disk drives, roundness measuring machines and optical scanners. Ultraprecision Bearings provides a detailed review of the different types of bearing and their properties, as well as an analysis of the factors that influence motion error, stiffness and damping. Following an introduction to basic principles of motion error, each chapter of the book is then devoted to the basic principles and properties of a specific type of bearin

  11. GRIZZLY Model of Multi-Reactive Species Diffusion, Moisture/Heat Transfer and Alkali-Silica Reaction for Simulating Concrete Aging and Degradation

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Hai [Idaho National Lab. (INL), Idaho Falls, ID (United States); Spencer, Benjamin W. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Cai, Guowei [Vanderbilt Univ., Nashville, TN (United States)

    2015-09-01

    Concrete is widely used in the construction of nuclear facilities because of its structural strength and its ability to shield radiation. The use of concrete in nuclear power plants for containment and shielding of radiation and radioactive materials has made its performance crucial for the safe operation of the facility. As such, when life extension is considered for nuclear power plants, it is critical to have accurate and reliable predictive tools to address concerns related to various aging processes of concrete structures and the capacity of structures subjected to age-related degradation. The goal of this report is to document the progress of the development and implementation of a fully coupled thermo-hydro-mechanical-chemical model in GRIZZLY code with the ultimate goal to reliably simulate and predict long-term performance and response of aged NPP concrete structures subjected to a number of aging mechanisms including external chemical attacks and volume-changing chemical reactions within concrete structures induced by alkali-silica reactions and long-term exposure to irradiation. Based on a number of survey reports of concrete aging mechanisms relevant to nuclear power plants and recommendations from researchers in concrete community, we’ve implemented three modules during FY15 in GRIZZLY code, (1) multi-species reactive diffusion model within cement materials; (2) coupled moisture and heat transfer model in concrete; and (3) anisotropic, stress-dependent, alkali-silica reaction induced swelling model. The multi-species reactive diffusion model was implemented with the objective to model aging of concrete structures subjected to aggressive external chemical attacks (e.g., chloride attack, sulfate attack, etc.). It considers multiple processes relevant to external chemical attacks such as diffusion of ions in aqueous phase within pore spaces, equilibrium chemical speciation reactions and kinetic mineral dissolution/precipitation. The moisture

  12. Gear bearing drive

    Science.gov (United States)

    Weinberg, Brian (Inventor); Mavroidis, Constantinos (Inventor); Vranish, John M. (Inventor)

    2011-01-01

    A gear bearing drive provides a compact mechanism that operates as an actuator providing torque and as a joint providing support. The drive includes a gear arrangement integrating an external rotor DC motor within a sun gear. Locking surfaces maintain the components of the drive in alignment and provide support for axial loads and moments. The gear bearing drive has a variety of applications, including as a joint in robotic arms and prosthetic limbs.

  13. Rolling bearing analysis

    CERN Document Server

    Harris, Tedric A

    2001-01-01

    One of the most well-known experts in the field brings cutting-edge research to practitioners in the new edition of this important reference. Covers the improved mathematical calculations for rolling bearing endurance developed by the American Society of Mechanical Engineers and the Society of Lubrication and Tribology Engineers. Updated with new material on Condition-Based Maintenance, new testing methods, and new bearing materials.

  14. My Little Teddy Bear

    Institute of Scientific and Technical Information of China (English)

    钱佳楠

    2005-01-01

    @@ As Valentine's Day came closer,every shop was full of colourful gifts such as cookies in the shape of heart, chocolates,Teddy Bears and so on.When I step into a shop on February 14th,I felt most lonely as I was alone.With mv eves fixed on a lovely Teddy Bear, I wished that someone could send me this stuffed toy.

  15. Ball Bearing Stacking Automation System

    Directory of Open Access Journals (Sweden)

    Shafeequerrahman S . Ahmed

    2013-01-01

    Full Text Available This document is an effort to introduce the concept of automation in small scale industries and or small workshops that are involved in the manufacturing of small objects such as nuts, bolts and ball bearing in this case. This an electromechanical system which includes certain mechanical parts that involves one base stand on which one vertical metallic frame is mounted and hinged to this vertical stand is an in humanized effort seems inadequate in this era making necessary the use of Electronics, Computer in the manufacturing processes leading to the concept of Automated Manufacturing System (AMS.The ball bearing stack automation is an effort in this regard. In our project we go for stack automation for any object for example a ball bearing, be that is still a manual system there. It will be microcontroller based project control system equipped with microcontroller 89C51 from any manufacturer like Atmel or Philips. This could have been easily implemented if a PLC could be used for manufacturing the staking unit but I adopted the microcontroller based system so that some more modification in the system can be effected at will as to use the same hardware .Although a very small object i.e. ball bearig or small nut and fixture will be tried to be stacked, the system with more precision and more power handling capacity could be built for various requirements of the industry. For increasing more control capacity, we can use another module of this series. When the bearing is ready, it will be sent for packing. This is sensed by an inductive sensor. The output will be proceeds by PLC and microcontroller card which will be driving the assembly in order to put it into pads or flaps. This project will also count the total number of bearings to be packed and will display it on a LCD for real time reference and a provision is made using a higher level language using hyper terminal of the computer

  16. Magnetic Bearing Consumes Low Power

    Science.gov (United States)

    Studer, P. A.

    1982-01-01

    Energy-efficient linear magnetic bearing maintains a precise small separation between its moving and stationary parts. Originally designed for cryogenic compressors on spacecraft, proposed magnetic bearing offers an alternative to roller or gas bearing in linear motion system. Linear noncontacting bearing operates in environments where lubricants cannot be used.

  17. Wear Analysis of Wind Turbine Gearbox Bearings

    Energy Technology Data Exchange (ETDEWEB)

    Blau, Peter Julian [ORNL; Walker, Larry R [ORNL; Xu, Hanbing [ORNL; Parten, Randy J [ORNL; Qu, Jun [ORNL; Geer, Tom [ORNL

    2010-04-01

    The objective of this effort was to investigate and characterize the nature of surface damage and wear to wind turbine gearbox bearings returned from service in the field. Bearings were supplied for examination by S. Butterfield and J. Johnson of the National Wind Technology Center (NREL), Boulder, Colorado. Studies consisted of visual examination, optical and electron microscopy, dimensional measurements of wear-induced macro-scale and micro-scale features, measurements of macro- and micro-scale hardness, 3D imaging of surface damage, studies of elemental distributions on fracture surfaces, and examinations of polished cross-sections of surfaces under various etched and non-etched conditions.

  18. Pitfalls in comparing modern hair and fossil bone collagen C and N isotopic data to reconstruct ancient diets: a case study with cave bears (Ursus spelaeus).

    Science.gov (United States)

    Bocherens, Hervé; Grandal-d'Anglade, Aurora; Hobson, Keith A

    2014-01-01

    Stable isotope analyses provide one of the few means to evaluate diet of extinct taxa. However, interpreting isotope data from bone collagen of extinct animals based on isotopic patterns in different tissues of modern animal proxies is precarious. For example, three corrections are needed before making comparisons of recent hair and ancient bone collagen: calibration of carbon-13 variations in atmospheric CO2, different isotopic discrimination between diet-hair keratin and diet-bone collagen, and time averaging of bone collagen versus short-term record in hair keratin. Recently, Robu et al. [Isotopic evidence for dietary flexibility among European Late Pleistocene cave bears (Ursus spelaeus). Can J Zool. 2013;91:227-234] published an article comparing extant carbon (δ(13)C) and nitrogen (δ(15)N) stable isotopic data of European cave bear bone collagen with those of Yellowstone Park grizzly bear hair in order to test the prevailing assumption of a largely vegetarian diet among cave bears. The authors concluded that cave bears were carnivores. This work is unfortunately unfounded as the authors failed to consider the necessary corrections listed above. When these corrections are applied to the Romanian cave bears, these individuals can be then interpreted without involving consumption of high trophic-level food, and environmental changes are probably the reason for the unusual isotopic composition of these cave bears in comparison with other European cave bears, rather than a change of diet. We caution researchers to pay careful attention to these factors when interpreting feeding ecology of extinct fauna using stable isotope techniques.

  19. Tribology of alternative bearings.

    Science.gov (United States)

    Fisher, John; Jin, Zhongmin; Tipper, Joanne; Stone, Martin; Ingham, Eileen

    2006-12-01

    The tribological performance and biological activity of the wear debris produced has been compared for highly cross-linked polyethylene, ceramic-on-ceramic, metal-on-metal, and modified metal bearings in a series of in vitro studies from a single laboratory. The functional lifetime demand of young and active patients is 10-fold greater than the estimated functional lifetime of traditional polyethylene. There is considerable interest in using larger diameter heads in these high demand patients. Highly cross-linked polyethylene show a four-fold reduction in functional biological activity. Ceramic-on-ceramic bearings have the lowest wear rates and least reactive wear debris. The functional biological activity is 20-fold lower than with highly cross-linked polyethylene. Hence, ceramic-on-ceramic bearings address the tribological lifetime demand of highly active patients. Metal-on-metal bearings have substantially lower wear rates than highly cross-linked polyethylene and wear decreases with head diameter. Bedding in wear is also lower with reduced radial clearance. Differential hardness ceramic-on-metal bearings and the application of ceramic-like coatings reduce metal wear and ion levels.

  20. Lidar-Based Mapping of Late Quaternary Faulting Along the Grizzly Valley Fault, Walker Lane Seismic Belt, California

    Science.gov (United States)

    Hitchcock, C. S.; Hoirup, D. F.; Barry, G.; Pearce, J.; Glick, F.

    2012-12-01

    The Grizzly Valley fault (GVF) is located within the northern Walker Lane, a zone of right-lateral shear between the Sierra Nevada and the Basin and Range in Plumas County. The GVF extends southeasterly from near Mt. Ingalls along the eastern side of Lake Davis. It may partially connect with the Hot Creek fault within Sierra Valley and extend south to Loyalton with an overall approximate length of 50 km. Comparison of high-resolution topography developed from LiDAR data with published bedrock geologic mapping documents the presence of geomorphic features that provide information on fault activity of the GVF. Field mapping verified tectonically deformed and offset late Quaternary surfaces identified on bare-earth LiDAR imagery across the GVF within glacial deposits on the eastern margin of Lake Davis, and alluvial deposits in Sierra Valley. Along the GVF, conspicuous geomorphic and hydrologic features include scarps in alluvial surfaces, elongated depressions aligned with adjacent linear escarpments, truncated bedrock spurs, closed depressions, linear swales, right-lateral deflections of creeks and river courses, and shutter ridges, as well as springs and linear seeps consistent with right-lateral strike-slip faulting. The discontinuous nature of observed fault traces combined with the apparent down-to-the-west offset of alluvial surfaces at the southern and northern ends of the eastern margin of Lake Davis are consistent with a broad bend or step over in the fault. Scarp profiles of apparently faulted surfaces extracted from LiDAR data document vertical offsets of up to 14 m. Our study suggest that the GVF is an oblique, right-lateral fault that has been active in the late Quaternary. This study complements on-going investigations by DWR to assess the impact of seismic hazards on State Water Project infrastructure.

  1. Radial Halbach Magnetic Bearings

    Science.gov (United States)

    Eichenberg, Dennis J.; Gallo, Christopher A.; Thompson, William K.

    2009-01-01

    Radial Halbach magnetic bearings have been investigated as part of an effort to develop increasingly reliable noncontact bearings for future high-speed rotary machines that may be used in such applications as aircraft, industrial, and land-vehicle power systems and in some medical and scientific instrumentation systems. Radial Halbach magnetic bearings are based on the same principle as that of axial Halbach magnetic bearings, differing in geometry as the names of these two types of bearings suggest. Both radial and axial Halbach magnetic bearings are passive in the sense that unlike most other magnetic bearings that have been developed in recent years, they effect stable magnetic levitation without need for complex active control. Axial Halbach magnetic bearings were described in Axial Halbach Magnetic Bearings (LEW-18066-1), NASA Tech Briefs, Vol. 32, No. 7 (July 2008), page 85. In the remainder of this article, the description of the principle of operation from the cited prior article is recapitulated and updated to incorporate the present radial geometry. In simplest terms, the basic principle of levitation in an axial or radial Halbach magnetic bearing is that of the repulsive electromagnetic force between (1) a moving permanent magnet and (2) an electric current induced in a stationary electrical conductor by the motion of the magnetic field. An axial or radial Halbach bearing includes multiple permanent magnets arranged in a Halbach array ("Halbach array" is defined below) in a rotor and multiple conductors in the form of wire coils in a stator, all arranged so the rotary motion produces an axial or radial repulsion that is sufficient to levitate the rotor. A basic Halbach array (see Figure 1) consists of a row of permanent magnets, each oriented so that its magnetic field is at a right angle to that of the adjacent magnet, and the right-angle turns are sequenced so as to maximize the magnitude of the magnetic flux density on one side of the row while

  2. Partial tooth gear bearings

    Science.gov (United States)

    Vranish, John M. (Inventor)

    2010-01-01

    A partial gear bearing including an upper half, comprising peak partial teeth, and a lower, or bottom, half, comprising valley partial teeth. The upper half also has an integrated roller section between each of the peak partial teeth with a radius equal to the gear pitch radius of the radially outwardly extending peak partial teeth. Conversely, the lower half has an integrated roller section between each of the valley half teeth with a radius also equal to the gear pitch radius of the peak partial teeth. The valley partial teeth extend radially inwardly from its roller section. The peak and valley partial teeth are exactly out of phase with each other, as are the roller sections of the upper and lower halves. Essentially, the end roller bearing of the typical gear bearing has been integrated into the normal gear tooth pattern.

  3. The Little Bear

    Institute of Scientific and Technical Information of China (English)

    林战峰; 乐伟国

    2007-01-01

    @@ 一、故事内容 A little bear has a magic stick.It can make his wishes come true. One day,the little bear is walking in the forest.He sees a bird.It is flying in the sky.It has two beautiful wings."I want two beautiful wings.I wish I can fly like a bird,"he says to the magic stick.Two beautiful wings come out from his back and he can fly like a bird now.He is very happy.

  4. Modular gear bearings

    Science.gov (United States)

    Vranish, John M. (Inventor)

    2009-01-01

    A gearing system using modular gear bearing components. Each component is composed of a core, one or more modules attached to the core and two or more fastening modules rigidly attaching the modules to the core. The modules, which are attached to the core, may consist of gears, rollers or gear bearing components. The core orientation affects the orientation of the modules attached to the core. This is achieved via the keying arrangement of the core and the component modules that attach to the core. Such an arrangement will also facilitate the phase tuning of gear modules with respect to the core and other gear modules attached to the core.

  5. Experimental investigations of active air bearings

    DEFF Research Database (Denmark)

    Santos, Ilmar; Morosi, Stefano

    2012-01-01

    Along with traditional oil lubrication, increasing demand for high-speed applications has renewed attention to gas bearings technology. Traditional aerostatic and aerodynamic gas lubrication has been widely used in a variety of applications, ranging from high-speed spindles to micro and meso......-scale turbomachinery. The present paper deals with experimental rotordynamic testing of a flexible rotor supported by hybrid aerostaticaerodynamic gas journal bearing equipped with an electronic radial air injection system. From a rotordynamic point of view there are two phenomena that limit the widespread...... of traditional gas lubrication: 1) Low damping makes operation across critical speed dangerous, as even low level of unbalance can generate large vibration responses. This is especially problematic for gas bearing applications, which often operate in the supercritical region. Moreover, 2) An upper bound...

  6. Hybrid superconductor magnet bearings

    Science.gov (United States)

    Chu, Wei-Kan

    1995-01-01

    Hybrid superconductor magnet bearings (HSMB's) utilize high temperature superconductors (HTS's) together with permanent magnets to form a frictionless interface between relatively rotating parts. They are low mass, stable, and do not incur expenditure of energy during normal operation. There is no direct physical contact between rotor and stator, and hence there is no wear and tear. However, just as any other applications of HTS's, it requires a very cold temperature to function. Whereas this might be perceived as a disadvantage on earth, it is of no great concern in space or on the moon. To astronomers, the moon is an excellent site for an observatory, but the cold and dusty vacuum environment on the moon precludes the use of mechanical bearings on the telescope mounts. Furthermore, drive mechanisms with very fine steps, and hence bearings with extremely low friction are needed to track a star from the moon, because the moon rotates very slowly. All aspects considered, the HSMB is about the only candidate that fits in naturally. Here, we present a design for one such bearing, capable of supporting a telescope that weighs about 3 lbs on Earth.

  7. Silver Bear for Screenplay

    Institute of Scientific and Technical Information of China (English)

    LIU YUNYUN

    2010-01-01

    @@ Chinese director Wang Quan'an won the Silver Bear Prize at the 60th Berlin International Film Festival that lasted during February 11 to 21 tor the best screenplay for his movie Apart Together.The film also opened the festival.

  8. Magnetic bearings for cryogenic turbomachines

    Science.gov (United States)

    Iannello, Victor; Sixsmith, Herbert

    1991-01-01

    Magnetic bearings offer a number of advantages over gas bearings for the support of rotors in cryogenic turboexpanders and compressors. Their performance is relatively independent of the temperature or pressure of the process gas for a large range of conditions. Active magnetic bearing systems that use capacitive sensors have been developed for high speed compressors for use in cryogenic refrigerators. Here, the development of a magnetic bearing system for a miniature ultra high speed compressor is discussed. The magnetic bearing has demonstrated stability at rotational speeds exceeding 250,000 rpm. This paper describes the important features of the magnetic bearing and presents test results demonstrating its performance characteristics.

  9. Government Risk-Bearing

    CERN Document Server

    1993-01-01

    The u.s. government bulks large in the nation's financial markets. The huge volume of government-issued and -sponsored debt affects the pricing and volume ofprivate debt and, consequently, resource allocation between competing alternatives. What is often not fully appreciated is the substantial influence the federal government wields overresource allocation through its provisionofcreditandrisk-bearing services to the private economy. Because peopleand firms generally seekto avoid risk, atsomeprice they are willing to pay another party to assume the risk they would otherwise face. Insurance companies are a class of private-sector firms one commonly thinks of as providing these services. As the federal government has expanded its presence in the U.S. economy during this century, it has increasingly developed programs aimed at bearing risks that the private sector either would not take on at any price, or would take on but atapricethoughtto besogreatthatmostpotentialbeneficiarieswouldnotpurchase the coverage. To...

  10. Centrifugally decoupling touchdown bearings

    Science.gov (United States)

    Post, Richard F

    2014-06-24

    Centrifugally decoupling mechanical bearing systems provide thin tensioned metallic ribbons contained in a support structure. This assembly rotates around a stationary shaft being centered at low speeds by the action of the metal ribbons. Tension springs are connected on one end to the ribbons and on the other end to the support structure. The ribbons pass through slots in the inner ring of the support structure. The spring preloading thus insures contact (or near-contact) between the ribbons and the shaft at rotation speeds below the transition speed. Above this speed, however, the centrifugal force on the ribbons produces a tensile force on them that exceeds the spring tensile force so that the ribbons curve outward, effectively decoupling them from mechanical contact with the shaft. They still remain, however, in position to act as a touchdown bearing in case of abnormally high transverse accelerations.

  11. Trend of Self-bearing Motors(Magnetic Bearings)

    OpenAIRE

    上野, 哲; Satoshi, UENO; 立命館大学

    2008-01-01

    This paper introduces a trend of a self-bearing motor that combines the functions of a motor and active magnetic bearing. The self-bearing motor has advantages, such as miniaturization, low cost, and high speed rotation in addition to the advantages of the active magnetic bearing. Various types of self-bearing motors such as a radial type, axial type, permanent magnet type, induction type, and reluctance type, have been proposed. In this paper, technologies and applications of the self-bearin...

  12. Leakage-free journal bearings

    Science.gov (United States)

    Pinkus, O.; Etsion, I.

    1976-01-01

    A new concept of a journal bearing is developed which prevents side leakage of the lubricant, thus eliminating the need for sealing and collecting this leakage. The cooling of the bearing is accomplished by the prevailing circumferential flow. An analysis is performed and solutions are given for the bearing geometries and inlet pressures required to achieve the above purpose.

  13. Tribological Behavior of Journal Bearing Material under Different Lubricants

    Directory of Open Access Journals (Sweden)

    S. Baskar

    2014-06-01

    Full Text Available The friction and wear behavior of journal bearing material has been investigated using pin on disc wear tester with three different lubricating oils i.e. synthetic lubricating oil (SAE20W40, chemically modified rapeseed oil (CMRO, chemically modified rapeseed oil with Nano CuO. Wear tests were carried out at maximum load of 200 N and sliding speeds of 2 – 10 m/s. The results showed that the friction and wear behavior of the journal bearing material have changed according to the sliding conditions and lubricating oils. The journal bearing material has a lower friction coefficient for CMRO with Nano CuO than other two oils. Higher wear of journal bearing material was observed in SAE 20W40 and CMRO. Worn surfaces of the journal bearing material with three lubricating oils were examined using scanning electron microscope (SEM and wear mechanisms were discussed.

  14. Vibration analysis of a bearing integrated sensor module

    Science.gov (United States)

    Suryavanshi, Abhijit P.; Gao, Robert X.

    2001-12-01

    Implementing a reliable condition monitoring system for bearing fault diagnosis and prognosis poses a big challenge to the industry. This challenge stems from the fact that bearing failure is statistical in nature, and thus contains elements of uncertainty and unpredictability. To achieve high accuracy in bearing diagnosis in spite of this inherent variance, reliable data acquisition and analysis techniques are needed. This paper focuses on the vibration analysis of a wireless transmitter module with an integrated sensor that is embedded into the bearing outer raceway for high signal-to-noise ratio data acquisition. A mechatronic design of the sensor module under severe space constraints is presented. The paper also analyses an optimizing scheme for the placement of sensor module substrate supports to reduce vibration transmitted from the bearing to the on-board electronics.

  15. Anti-backlash gear bearings

    Science.gov (United States)

    Vranish, John M. (Inventor)

    2009-01-01

    A gear bearing having a first gear and a second gear, each having a plurality of teeth. Each gear operates on two non-parallel surfaces of the opposing gear teeth to perform both gear and bearing functions simultaneously. The gears are moving at substantially the same speed at their contact points. The gears may be roller gear bearings or phase-shifted gear bearings, and may be arranged in a planet/sun system or used as a transmission. One preferred embodiment discloses and describes an anti-backlash feature to counter ''dead zones'' in the gear bearing movement.

  16. Damping Bearings In High-Speed Turbomachines

    Science.gov (United States)

    Von Pragenau, George L.

    1994-01-01

    Paper presents comparison of damping bearings with traditional ball, roller, and hydrostatic bearings in high-speed cryogenic turbopumps. Concept of damping bearings described in "Damping Seals and Bearings for a Turbomachine" (MFS-28345).

  17. Aerospace applications of magnetic bearings

    Science.gov (United States)

    Downer, James; Goldie, James; Gondhalekar, Vijay; Hockney, Richard

    1994-01-01

    Magnetic bearings have traditionally been considered for use in aerospace applications only where performance advantages have been the primary, if not only, consideration. Conventional wisdom has been that magnetic bearings have certain performance advantages which must be traded off against increased weight, volume, electric power consumption, and system complexity. These perceptions have hampered the use of magnetic bearings in many aerospace applications because weight, volume, and power are almost always primary considerations. This paper will review progress on several active aerospace magnetic bearings programs at SatCon Technology Corporation. The magnetic bearing programs at SatCon cover a broad spectrum of applications including: a magnetically-suspended spacecraft integrated power and attitude control system (IPACS), a magnetically-suspended momentum wheel, magnetic bearings for the gas generator rotor of a turboshaft engine, a vibration-attenuating magnetic bearing system for an airborne telescope, and magnetic bearings for the compressor of a space-rated heat pump system. The emphasis of these programs is to develop magnetic bearing technologies to the point where magnetic bearings can be truly useful, reliable, and well tested components for the aerospace community.

  18. Nanoprecipitation in bearing steels

    Energy Technology Data Exchange (ETDEWEB)

    Barrow, A.T.W. [SKF University Technology Centre, Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB2 3QZ (United Kingdom); Rivera-Diaz-del-Castillo, P.E.J., E-mail: pejr2@cam.ac.uk [SKF University Technology Centre, Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB2 3QZ (United Kingdom)

    2011-11-15

    {theta}-phase is the main hardening species in bearing steels and appears in both martensitically and bainitically hardened microstructures. This work presents a survey of the microstrucural features accompanying nanoprecipitation in bearing steels. Nanoprecipitate structures formed in 1C-1.5Cr wt.% with additions of Cr, Mn, Mo, Si and Ni are studied. The work is combined with thermodynamic calculations and neural networks to predict the expected matrix composition, and whether this will transform martensitically or bainitically. Martensite tetragonality, composition and the amount of retained austenite are related to hardness and the type of nanoprecipitate structures in martensitic grades. The {theta}-phase volume fraction, the duration of the bainite to austenite transformation and the amount of retained austenite are related to hardness and a detailed quantitative description of the precipitate nanostructures. Such description includes compositional studies using energy-dispersive spectroscopy, which shows that nanoprecipitate formation takes place under paraequilibrium. Special attention is devoted to a novel two-step bainite tempering process which shows maximum hardness; we prove that this is the most effective process for incorporating solute into the precipitates, which are finer than those resulting from one-step banitic transformation processes.

  19. 78 FR 26064 - Endangered and Threatened Wildlife and Plants; Draft Conservation Strategy for the Northern...

    Science.gov (United States)

    2013-05-03

    ... for the Northern Continental Divide Ecosystem Grizzly Bear AGENCY: Fish and Wildlife Service, Interior... Divide Ecosystem grizzly bear (Ursus arctos horriblis) population for public review and input. The strategy will be the post- delisting management plan for the NCDE grizzly bears and their habitat....

  20. Computational design of rolling bearings

    CERN Document Server

    Nguyen-Schäfer, Hung

    2016-01-01

    This book comprehensively presents the computational design of rolling bearings dealing with many interdisciplinary difficult working fields. They encompass elastohydrodynamics (EHD), Hertzian contact theory, oil-film thickness in elastohydrodynamic lubrication (EHL), bearing dynamics, tribology of surface textures, fatigue failure mechanisms, fatigue lifetimes of rolling bearings and lubricating greases, Weibull distribution, rotor balancing, and airborne noises (NVH) in the rolling bearings. Furthermore, the readers are provided with hands-on essential formulas based on the up-to-date DIN ISO norms and helpful examples for computational design of rolling bearings. The topics are intended for undergraduate and graduate students in mechanical and material engineering, research scientists, and practicing engineers who want to understand the interactions between these working fields and to know how to design the rolling bearings for automotive industry and many other industries.

  1. Prototype testing of magnetic bearings

    Science.gov (United States)

    Plant, David P.; Jayaraman, Chaitanya P.; Frommer, David A.; Kirk, James A.; Anand, Davinder K.

    1987-01-01

    The testing and evaluation of the performance of a magnetic bearing assembly for flywheel energy storage applications are discussed. The experimental set up for determining the passive radial stiffness, active radial stiffness, and curent force sensitivity of the coils follows the method developed by Frommer (1986). Magnetic bearings design should preclude saturation and current limiting in the desired operating range, so that the system will be linear. A larger linear range will lead to a more stable magnetic bearing.

  2. Grease lubrication in rolling bearings

    CERN Document Server

    Lugt, Piet M

    2012-01-01

    The definitive book on the science of grease lubrication for roller and needle bearings in industrial and vehicle engineering. Grease Lubrication in Rolling Bearings provides an overview of the existing knowledge on the various aspects of grease lubrication (including lubrication systems) and the state of the art models that exist today. The book reviews the physical and chemical aspects of grease lubrication, primarily directed towards lubrication of rolling bearings. The first part of the book covers grease composition, properties and rheology, including thermal

  3. Failure analysis of a bearing in a helicopter turbine engine due to electrical discharge damage

    Directory of Open Access Journals (Sweden)

    Michael K. Budinski

    2014-10-01

    Full Text Available This article documents the metallurgical evaluation of a rolling element bearing that failed due to electrical discharge damage. This rolling element bearing was used in a helicopter turbine engine that failed in-flight, resulting in a hard landing of the helicopter. Optical and electron microscopy as well as energy dispersive spectroscopy were used to evaluate the bearing. Pitting and material transfer on the external bearing races bearing and mating surfaces revealed that the electrical discharge damage occurred while the engine's components were not rotating.

  4. Cyanines Bearing Quaternary Azaaromatic Moieties

    OpenAIRE

    Sbliwa, Wanda; Matusiak, Grazyna; Bachowska, Barbara

    2006-01-01

    Selected cyanines bearing quaternary azaaromatic moieties are presented, showing their monomers, dimers and polymers, as well as their possible applications. Cyanines having NLO properties are also briefly described.

  5. Hydrostatic and hybrid bearing design

    CERN Document Server

    Rowe, W B

    1983-01-01

    Hydrostatic and Hybrid Bearing Design is a 15-chapter book that focuses on the bearing design and testing. This book first describes the application of hydrostatic bearings, as well as the device pressure, flow, force, power, and temperature. Subsequent chapters discuss the load and flow rate of thrust pads; circuit design, flow control, load, and stiffness; and the basis of the design procedures and selection of tolerances. The specific types of bearings, their design, dynamics, and experimental methods and testing are also shown. This book will be very valuable to students of engineering des

  6. Novel Integration Radial and Axial Magnetic Bearing

    Science.gov (United States)

    Blumenstock, Kenneth; Brown, Gary

    2000-01-01

    Typically, fully active magnetically suspended systems require one axial and two radial magnetic bearings. Combining radial and axial functions into a single device allows for more compact and elegant packaging. Furthermore, in the case of high-speed devices such as energy storage flywheels, it is beneficial to minimize shaft length to keep rotor mode frequencies as high as possible. Attempts have been made to combine radial and axial functionality, but with certain drawbacks. One approach requires magnetic control flux to flow through a bias magnet reducing control effectiveness, thus resulting in increased resistive losses. This approach also requires axial force producing magnetic flux to flow in a direction into the rotor laminate that is undesirable for minimizing eddy-current losses resulting in rotational losses. Another approach applies a conical rotor shape to what otherwise would be a radial heteropolar magnetic bearing configuration. However, positional non-linear effects are introduced with this scheme and the same windings are used for bias, radial, and axial control adding complexity to the controller and electronics. For this approach, the amount of axial capability must be limited. It would be desirable for an integrated radial and axial magnetic bearing to have the following characteristics; separate inputs for radial and axial control for electronics and control simplicity, all magnetic control fluxes should only flow through their respective air gaps and should not flow through any bias magnets for minimal resistive losses, be of a homopolar design to minimize rotational losses, position related non-linear effects should be minimized, and dependent upon the design parameters, be able to achieve any radial/axial force or power ratio as desired. The integrated radial and axial magnetic bearing described in this paper exhibits all these characteristics. Magnetic circuit design, design equations, and magnetic field modeling results will be presented.

  7. Novel Integrated Radial and Axial Magnetic Bearing

    Science.gov (United States)

    Blumenstock, Kenneth A.; Brown, Gary L.; Powers, Edward I. (Technical Monitor)

    2000-01-01

    Typically, fully active magnetically suspended systems require one axial and two radial magnetic bearings. Combining radial and axial functions into a single device allows for more compact and elegant packaging. Furthermore, in the case of high-speed devices such as energy storage flywheels, it is beneficial to minimize shaft length to keep rotor mode frequencies as high as possible. Attempts have been made to combine radial and axial functionality, but with certain drawbacks. One approach requires magnetic control flux to flow through a bias magnet reducing control effectiveness, thus resulting in increased resistive losses. This approach also requires axial force producing magnetic flux to flow in a direction into the rotor laminate that is undesirable for minimizing eddy-current losses resulting in rotational losses. Another approach applies a conical rotor shape to what otherwise would be a radial heteropolar magnetic bearing configuration. However, positional non-linear effects are introduced with this scheme and the same windings are used for bias, radial, and axial control adding complexity to the controller and electronics. For this approach, the amount of axial capability must be limited. It would be desirable for an integrated radial and axial magnetic bearing to have the following characteristics, separate inputs for radial and axial control for electronics and control simplicity, all magnetic control fluxes should only flow through their respective air gaps and should not flow through any bias magnets for minimal resistive losses, be of a homopolar design to minimize rotational losses, position related non-linear effects should be minimized, and dependent upon the design parameters, be able to achieve any radial/axial force or power ratio as desired. The integrated radial and axial magnetic bearing described in this paper exhibits all these characteristics. Magnetic circuit design, design equations, and analysis results will be presented.

  8. Patterns of risk of cancer in patients with metal-on-metal hip replacements versus other bearing surface types: a record linkage study between a prospective joint registry and general practice electronic health records in England.

    Directory of Open Access Journals (Sweden)

    Arief Lalmohamed

    Full Text Available BACKGROUND: There are concerns that metal-on-metal hip implants may cause cancer. The objective of this study was to evaluate patterns and timing of risk of cancer in patients with metal-on-metal total hip replacements (THR. METHODS: In a linkage study between the English National Joint Registry (NJR and the Clinical Practice Research Datalink (CPRD, we selected all THR surgeries (NJR between 2003 and 2010 (n = 11,540. THR patients were stratified by type of bearing surface. Patients were followed up for cancer and Poisson regression was used to derive adjusted relative rates (RR. RESULTS: The risk of cancer was similar in patients with hip resurfacing (RR 0.69; 95% Confidence Interval [CI] 0.39-1.22 or other types of bearing surfaces (RR 0.96; 95% CI 0.64-1.43 compared to individuals with stemmed metal-on-metal THR. The pattern of cancer risk over time did not support a detrimental effect of metal hip implants. There was substantial confounding: patients with metal-on-metal THRs used fewer drugs and had less comorbidity. CONCLUSIONS: Metal-on-metal THRs were not associated with an increased risk of cancer. There were substantial baseline differences between the different hip implants, indicating possibility of confounding in the comparisons between different types of THR implants.

  9. High-Performance Ball Bearing

    Science.gov (United States)

    Bursey, Roger W., Jr.; Haluck, David A.; Olinger, John B.; Owen, Samuel S.; Poole, William E.

    1995-01-01

    High-performance bearing features strong, lightweight, self-lubricating cage with self-lubricating liners in ball apertures. Designed to operate at high speed (tens of thousands of revolutions per minute) in cryogenic environment like liquid-oxygen or liquid-hydrogen turbopump. Includes inner race, outer race, and cage keeping bearing balls equally spaced.

  10. Permanent-Magnet Meissner Bearing

    Science.gov (United States)

    Robertson, Glen A.

    1994-01-01

    Permanent-magnet meissner bearing features inherently stable, self-centering conical configuration. Bearing made stiffer or less stiff by selection of magnets, springs, and spring adjustments. Cylindrical permanent magnets with axial magnetization stacked coaxially on rotor with alternating polarity. Typically, rare-earth magnets used. Magnets machined and fitted together to form conical outer surface.

  11. High-Performance Ball Bearing

    Science.gov (United States)

    Bursey, Roger W., Jr.; Haluck, David A.; Olinger, John B.; Owen, Samuel S.; Poole, William E.

    1995-01-01

    High-performance bearing features strong, lightweight, self-lubricating cage with self-lubricating liners in ball apertures. Designed to operate at high speed (tens of thousands of revolutions per minute) in cryogenic environment like liquid-oxygen or liquid-hydrogen turbopump. Includes inner race, outer race, and cage keeping bearing balls equally spaced.

  12. Superconducting bearings for flywheel applications

    DEFF Research Database (Denmark)

    Abrahamsen, A.B.

    2001-01-01

    A literature study on the application of superconducting bearings in energy storage flywheel systems. The physics of magnetic levitation and superconductors are presented in the first part of the report, followed by a discussion of the literature found onthe applications of superconducting bearings...

  13. What about the Javan Bear?

    NARCIS (Netherlands)

    Jentink, F.A.

    1898-01-01

    The other day I read in a dutch popular periodical a paper dealing with the different species of Bears and their geographical distribution. To my great surprise the Malayan Bear was mentioned from Java: the locality Java being quite new to me I wrote to the author of that paper and asked him some in

  14. Grizzly Staus Report

    Energy Technology Data Exchange (ETDEWEB)

    Spencer, Benjamin [Idaho National Lab. (INL), Idaho Falls, ID (United States); Zhang, Yongfeng [Idaho National Lab. (INL), Idaho Falls, ID (United States); Chakraborty, Pritam [Idaho National Lab. (INL), Idaho Falls, ID (United States); Backman, Marie [Idaho National Lab. (INL), Idaho Falls, ID (United States); Hoffman, William [Idaho National Lab. (INL), Idaho Falls, ID (United States); Schwen, Daniel [Idaho National Lab. (INL), Idaho Falls, ID (United States); Biner, S. Bulent [Idaho National Lab. (INL), Idaho Falls, ID (United States); Bai, Xianming [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2014-09-01

    This report summarizes work during FY 2014 to develop capabilities to predict embrittlement of reactor pressure vessel steel, and to assess the response of embrittled reactor pressure vessels to postulated accident conditions. This work has been conducted a three length scales. At the engineering scale, 3D fracture mechanics capabilities have been developed to calculate stress intensities and fracture toughnesses, to perform a deterministic assessment of whether a crack would propagate at the location of an existing flaw. This capability has been demonstrated on several types of flaws in a generic reactor pressure vessel model. Models have been developed at the scale of fracture specimens to develop a capability to determine how irradiation affects the fracture toughness of material. Verification work has been performed on a previously-developed model to determine the sensitivity of the model to specimen geometry and size effects. The effects of irradiation on the parameters of this model has been investigated. At lower length scales, work has continued in an ongoing to understand how irradiation and thermal aging affect the microstructure and mechanical properties of reactor pressure vessel steel. Previously-developed atomistic kinetic monte carlo models have been further developed and benchmarked against experimental data. Initial work has been performed to develop models of nucleation in a phase field model. Additional modeling work has also been performed to improve the fundamental understanding of the formation mechanisms and stability of matrix defects caused.

  15. Space Station alpha joint bearing

    Science.gov (United States)

    Everman, Michael R.; Jones, P. Alan; Spencer, Porter A.

    1987-01-01

    Perhaps the most critical structural system aboard the Space Station is the Solar Alpha Rotary Joint which helps align the power generation system with the sun. The joint must provide structural support and controlled rotation to the outboard transverse booms as well as power and data transfer across the joint. The Solar Alpha Rotary Joint is composed of two transition sections and an integral, large diameter bearing. Alpha joint bearing design presents a particularly interesting problem because of its large size and need for high reliability, stiffness, and on orbit maintability. The discrete roller bearing developed is a novel refinement to cam follower technology. It offers thermal compensation and ease of on-orbit maintenance that are not found in conventional rolling element bearings. How the bearing design evolved is summarized. Driving requirements are reviewed, alternative concepts assessed, and the selected design is described.

  16. AN INVESTIGATION OF MAGNETIC BEARING SYSTEMS

    Directory of Open Access Journals (Sweden)

    Gürcan SAMTAŞ

    2007-02-01

    Full Text Available The magnetic bearing consists of levitating a shaft so that it is free to rotate about its axis. The magnetic bearing has the advantages of being very quiet work and very cleanliness because there is no mechanical friction or lubricants. The shaft has two permanent magnets attached to it. These two magnets determine a straight line rotation axis of the rotor shaft. The magnets are radially levitated and centered within a cavity by a passive permanent magnetic field in the adding stator housing assembly. The levitation and centering of the shaft axially is stabilized by a closed loop electronic servo circuit that regulates an electromagnetic field in the stator housing that pushes and pulls on the shaft magnets. The rotor weight can be between one gram and forty five thousand, four hundred grams. In 1985, the first magnetic bearing was developed that it had used to applications of gas turbines and other compressors. In these days, they can be used by many applications which are Medical, Transportation, Machine and Tools Industry, Aerospace, Vacuum and Clean room Environments... etc.

  17. Get fit with the Grizzlies: a community-school-home initiative to fight childhood obesity led by a professional sports organization.

    Science.gov (United States)

    Irwin, Carol; Irwin, Richard; Richey, Phyllis; Miller, Maureen; Boddie, Justin; Dickerson, Teresa

    2012-01-01

    Professional sports organizations in the United States have notable celebrity status, and several teams have used this "star power" to collaborate with local schools toward the goal of affecting childhood obesity (e.g., NFL Play 60). Program effectiveness is unknown owing to the absence of comprehensive evaluations for any of these initiatives. In 2006, the Memphis Grizzlies, the city's National Basketball Association (NBA) franchise, launched "Get Fit with the Grizzlies," a 6-week, curricular addition focusing on nutrition and physical activity for the 4th and 5th grades in Memphis City Schools. The health-infused mini-unit was delivered by the physical education teachers during their classes. National and local sponsors whose business objectives matched the "Get Fit" objectives were solicited to fund the program. Here we highlight the program evaluation results from the first year of "Get Fit" and the Journal of School Health article. However, the "Get Fit" program has now taken place in Memphis area schools for 5 years. During the 2010-11 school-year, "Get Fit" evolved into a new program called "Healthy Home Court" with Kellogg's as the primary sponsor. "Healthy Home Court" included the original fitness part of the program and added a breakfast component at high schools where data indicated great need. Kellogg's sponsored special "carts" with healthy breakfast options (i.e., fruit, protein bars) for students to grab and eat. This program matched their existing program "Food Away from Home." Research supports the objectives of these programs and has shown that breakfast consumption can have a positive impact on academic achievement, behavior in school, and overall health status. Survey research employed over the first 4 years measured health knowledge acquisition and health behavior change using a matched pre/post test design (n=2210) in randomly chosen schools (n=18) from all elementary schools in the Memphis area. McNemar's test for significance (<05) was

  18. Magnetic Bearings at Draper Laboratory

    Science.gov (United States)

    Kondoleon, Anthony S.; Kelleher, William P.; Possel, Peter D.

    1996-01-01

    Magnetic bearings, unlike traditional mechanical bearings, consist of a series of components mated together to form a stabilized system. The correct design of the actuator and sensor will provide a cost effective device with low power requirements. The proper choice of a control system utilizes the variables necessary to control the system in an efficient manner. The specific application will determine the optimum design of the magnetic bearing system including the touch down bearing. Draper for the past 30 years has been a leader in all these fields. This paper summarizes the results carried out at Draper in the field of magnetic bearing development. A 3-D radial magnetic bearing is detailed in this paper. Data obtained from recently completed projects using this design are included. One project was a high radial load (1000 pound) application. The second was a high speed (35,000 rpm), low loss flywheel application. The development of a low loss axial magnetic bearing is also included in this paper.

  19. EFFECT OF BEARING MACROGEOMETRY ON BEARING PERFORMANCE IN ELASTOHYDRODYNAMIC LUBRICATION

    Directory of Open Access Journals (Sweden)

    Emin GÜLLÜ

    2000-01-01

    Full Text Available During manufacturing, ideal dimension and mutual positioning of machine elements proposed in project desing can be achieved only within certain range of tolerances. These tolerances, being classified in two groups, related to micro and macro geometry of machine elements, don't have to effect the functioning of these elements. So, as for all machine elements, investigation of the effects of macro and micro tolerances for journal bearings is important. In this study, we have investigated the effect of macro geometric irregularities of journal bearings on performance characteristics. In this regard, we have studied the change of bearing performance in respect to deviation from ideal circle for an elliptic shaft with small ovality rolling in circular journal bearing.

  20. Non-contacting "snubber bearing" for passive magnetic bearing systems

    Energy Technology Data Exchange (ETDEWEB)

    Post, Richard F

    2017-08-22

    A new non-contacting magnetic "snubber" bearing is provided for application to rotating systems such as vehicular electromechanical battery systems subject to frequent accelerations. The design is such that in the equilibrium position the drag force of the snubber is very small (milliwatts). However in a typical case, if the rotor is displaced by as little as 2 millimeters a large restoring force is generated without any physical contact between the stationary and rotating parts of the snubber bearing.

  1. Effect of Bearing Defects

    Science.gov (United States)

    1974-12-01

    or wash them in a suitable solvent. ( ) •To Install 1. Draw 2 cc’s of 2000 centistoke silicone fluid into a hypodermic syringe (without needle ). Put...millimeters per minor division. 2. Theory of Operation Fig. 1 shows the complete Mark III Running Torque Tester. Left to right is the electronic...vibration and performance. 0 - 92 - SECTION I I II. Theory of the VANT The MPB VANT (vibration and noise tester) is of the moving coil design with a

  2. Berkeley extreme-ultraviolet airglow rocket spectrometer - BEARS

    Science.gov (United States)

    Cotton, D. M.; Chakrabarti, S.

    1992-01-01

    The Berkeley EUV airglow rocket spectrometer (BEARS) instrument is described. The instrument was designed in particular to measure the dominant lines of atomic oxygen in the FUV and EUV dayglow at 1356, 1304, 1027, and 989 A, which is the ultimate source of airglow emissions. The optical and mechanical design of the instrument, the detector, electronics, calibration, flight operations, and results are examined.

  3. A Passive Magnetic Bearing Flywheel

    Science.gov (United States)

    Siebert, Mark; Ebihara, Ben; Jansen, Ralph; Fusaro, Robert L.; Morales, Wilfredo; Kascak, Albert; Kenny, Andrew

    2002-01-01

    A 100 percent passive magnetic bearing flywheel rig employing no active control components was designed, constructed, and tested. The suspension clothe rotor was provided by two sets of radial permanent magnetic bearings operating in the repulsive mode. The axial support was provided by jewel bearings on both ends of the rotor. The rig was successfully operated to speeds of 5500 rpm, which is 65 percent above the first critical speed of 3336 rpm. Operation was not continued beyond this point because of the excessive noise generated by the air impeller and because of inadequate containment in case of failure. Radial and axial stiffnesses of the permanent magnetic bearings were experimentally measured and then compared to finite element results. The natural damping of the rotor was measured and a damping coefficient was calculated.

  4. Gas bearing operates in vacuum

    Science.gov (United States)

    Perkins, G. S.

    1975-01-01

    Bearing has restrictions to reduce air leaks and is connected to external pumpout facility which removes exhausted air. Token amount of air which is lost to vacuum is easily removed by conventional vacuum pump.

  5. Mixed-mu superconducting bearings

    Energy Technology Data Exchange (ETDEWEB)

    Hull, John R. (Hinsdale, IL); Mulcahy, Thomas M. (Western Springs, IL)

    1998-01-01

    A mixed-mu superconducting bearing including a ferrite structure disposed for rotation adjacent a stationary superconductor material structure and a stationary permanent magnet structure. The ferrite structure is levitated by said stationary permanent magnet structure.

  6. Segmented Hybrid Gasostatic Bearing Optimization

    Directory of Open Access Journals (Sweden)

    Prodan Nikolay Vasilevich

    2014-07-01

    Full Text Available The purpose of research-development of methods of numerical optimization rotatable support pads gasostatic hybrid bearing. In the world‘s aerospace engineering the gas-dynamic bearings are currently most common. They are characterized by the supporting layer of different designs, which ensures the workability of the rotors during starts and stops. The main problem of this bearing type, apart from the construction complexity is the wear of this supporting layer. Gas-static bearing has no such defect, since there is no physical contact between solid surfaces. This study presents the results of the hybrid bearing’s calculation, combining both technologies. The slotted nozzle of non-conventional shape that mirrors the solution of Reynolds equation’s isoline is studied. The dependences of the main parameters on the speed of the shaft’s rotation are discussed. The aerodynamic resistance of pads for different regimes of operation is investigated.

  7. Bear study, Karluk Lake, 1956

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Based on observations, 117 bears were estimated to live in the Karluk Lake area. The estimate was lower than estimates from 1952, and 1954-1955. Annual loss to...

  8. Nonlinear Control of Magnetic Bearings

    Institute of Scientific and Technical Information of China (English)

    Khac Duc Do; Dang Hoe Nguyen; Thanh Binh Nguyen

    2010-01-01

    In this paper, recent results controling nonlinear systems with output tracking error constraints are applied to the design of new tracking controllers for magnetic bearings. The proposed controllers can force the rotor to track a bounded and sufficiently smooth refer-ence trajectory asymptotically and guarantee non-contactedness be-tween the rotor and the stator of the magnetic bearings. Simulation results are included to illustrate the effectiveness of the proposed con-trollers.

  9. 77 FR 70423 - Black Bear Hydro Partners, LLC and Black Bear Development Holdings, LLC and Black Bear SO, LLC...

    Science.gov (United States)

    2012-11-26

    ... Energy Regulatory Commission Black Bear Hydro Partners, LLC and Black Bear Development Holdings, LLC and Black Bear SO, LLC; Notice of Application for Partial Transfer of Licenses, and Soliciting Comments and Motions To Intervene On October 25, 2012, Black Bear Hydro Partners, LLC, sole licensee (transferor)...

  10. Superconductor bearings, flywheels and transportation

    Science.gov (United States)

    Werfel, F. N.; Floegel-Delor, U.; Rothfeld, R.; Riedel, T.; Goebel, B.; Wippich, D.; Schirrmeister, P.

    2012-01-01

    This paper describes the present status of high temperature superconductors (HTS) and of bulk superconducting magnet devices, their use in bearings, in flywheel energy storage systems (FESS) and linear transport magnetic levitation (Maglev) systems. We report and review the concepts of multi-seeded REBCO bulk superconductor fabrication. The multi-grain bulks increase the averaged trapped magnetic flux density up to 40% compared to single-grain assembly in large-scale applications. HTS magnetic bearings with permanent magnet (PM) excitation were studied and scaled up to maximum forces of 10 kN axially and 4.5 kN radially. We examine the technology of the high-gradient magnetic bearing concept and verify it experimentally. A large HTS bearing is tested for stabilizing a 600 kg rotor of a 5 kWh/250 kW flywheel system. The flywheel rotor tests show the requirement for additional damping. Our compact flywheel system is compared with similar HTS-FESS projects. A small-scale compact YBCO bearing with in situ Stirling cryocooler is constructed and investigated for mobile applications. Next we show a successfully developed modular linear Maglev system for magnetic train operation. Each module levitates 0.25t at 10 mm distance during one-day operation without refilling LN2. More than 30 vacuum cryostats containing multi-seeded YBCO blocks are fabricated and are tested now in Germany, China and Brazil.

  11. Magnetic bearings with zero bias

    Science.gov (United States)

    Brown, Gerald V.; Grodsinsky, Carlos M.

    1991-01-01

    A magnetic bearing operating without a bias field has supported a shaft rotating at speeds up to 12,000 rpm with the usual four power supplies and with only two. A magnetic bearing is commonly operated with a bias current equal to half of the maximum current allowable in its coils. This linearizes the relation between net force and control current and improves the force slewing rate and hence the band width. The steady bias current dissipates power, even when no force is required from the bearing. The power wasted is equal to two-thirds of the power at maximum force output. Examined here is the zero bias idea. The advantages and disadvantages are noted.

  12. P-Fluorous Phosphines as Electron-Poor/Fluorous Hybrid Functional Ligands for Precious Metal Catalysts: Synthesis of Rh(I, Ir(I, Pt(II, and Au(I Complexes Bearing P-Fluorous Phosphine Ligands

    Directory of Open Access Journals (Sweden)

    Shin-ichi Kawaguchi

    2017-01-01

    Full Text Available P-Fluorous phosphine (R2PRf, in which the perfluoroalkyl group is directly bonded to the phosphorus atom, is a promising ligand because it has a hybrid functionality, i.e., electron-poor and fluorous ligands. However, examples of P-fluorous phosphine–metal complexes are still rare, most probably because the P-fluorous group is believed to decrease the coordination ability of the phosphines dramatically. In contrast, however, we have succeeded in synthesizing a series of P-fluorous phosphine–coordinated metal complexes such as rhodium, iridium, platinum, and gold. Furthermore, the electronic properties of R2PnC10F21 are investigated by X-ray analysis of PtCl2(Ph2PnC10F212 and the infrared CO stretching frequency of RhCl(CO(R2PnC10F212. IrCl(CO(Ph2PnC10F212- and AuCl(R2PnC10F21-catalyzed reactions are also demonstrated.

  13. j200sf.m77t and j200sf.h77t: MGD77T data and header files for single-beam bathymetry data for field activity J-2-00-SF in Grizzly Bay, San Pablo Bay from 03/22/2000 to 03/27/2000

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Single-beam bathymetry data along with GPS navigation data was collected as part of the U.S. Geological Survey cruise J-2-00-SF. The cruise was conducted in Grizzly...

  14. j299sf.m77t and j299sf.h77t: MGD77T data and header files for single-beam bathymetry data for field activity J-2-99-SF in Grizzly Bay, San Francisco Bay from 02/24/1999 to 03/08/1999

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Single-beam bathymetry data along with DGPS navigation data was collected as part of the U.S. Geological Survey cruise J-2-99-SF. The cruise was conducted in Grizzly...

  15. j200sf.m77t and j200sf.h77t: MGD77T data and header files for single-beam bathymetry data for field activity J-2-00-SF in Grizzly Bay, San Pablo Bay from 03/22/2000 to 03/27/2000

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Single-beam bathymetry data along with GPS navigation data was collected as part of the U.S. Geological Survey cruise J-2-00-SF. The cruise was conducted in Grizzly...

  16. j299sf.m77t and j299sf.h77t: MGD77T data and header files for single-beam bathymetry data for field activity J-2-99-SF in Grizzly Bay, San Francisco Bay from 02/24/1999 to 03/08/1999

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Single-beam bathymetry data along with DGPS navigation data was collected as part of the U.S. Geological Survey cruise J-2-99-SF. The cruise was conducted in Grizzly...

  17. j399sf.m77t and j399sf.h77t: MGD77T data and header files for single-beam bathymetry data for field activity J-3-99-SF in Grizzly Bay, San Francisco Bay from 11/08/1999 to 11/18/1999

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Single-beam bathymetry data along with DGPS navigation data was collected as part of the U.S. Geological Survey cruise J-3-99-SF. The cruise was conducted in Grizzly...

  18. j100sf.m77t and j100sf.h77t: MGD77T data and header files for single-beam bathymetry data for field activity J-1-00-SF in Grizzly Bay and Suisun Bay from 03/13/2000 to 03/14/2000

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Single-beam bathymetry data along with GPS navigation data was collected as part of the U.S. Geological Survey cruise J-1-00-SF. The cruise was conducted in Grizzly...

  19. j399sf.m77t and j399sf.h77t: MGD77T data and header files for single-beam bathymetry data for field activity J-3-99-SF in Grizzly Bay, San Francisco Bay from 11/08/1999 to 11/18/1999

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Single-beam bathymetry data along with DGPS navigation data was collected as part of the U.S. Geological Survey cruise J-3-99-SF. The cruise was conducted in Grizzly...

  20. BEARS: Radioactive ion beams at LBNL

    Energy Technology Data Exchange (ETDEWEB)

    Powell, J.; Guo, F.Q. [Lawrence Berkeley National Lab., CA (United States); Haustein, P.E. [Brookhaven National Lab., Upton, NY (United States). Chemistry Dept.] [and others

    1998-07-01

    BEARS (Berkeley Experiments with Accelerated Radioactive Species) is an initiative to develop a radioactive ion-beam capability at Lawrence Berkeley National Laboratory. The aim is to produce isotopes at an existing medical cyclotron and to accelerate them at the 88 inch Cyclotron. To overcome the 300-meter physical separation of these two accelerators, a carrier-gas transport system will be used. At the terminus of the capillary, the carrier gas will be separated and the isotopes will be injected into the 88 inch Cyclotron`s Electron Cyclotron Resonance (ECR) ion source. The first radioactive beams to be developed will include 20-min {sup 11}C and 70-sec {sup 14}O, produced by (p,n) and (p,{alpha}) reactions on low-Z targets. A test program is currently being conducted at the 88 inch Cyclotron to develop the parts of the BEARS system. Preliminary results of these tests lead to projections of initial {sup 11}C beams of up to 2.5 {times} 10{sup 7} ions/sec and {sup 14}O beams of 3 {times} 10{sup 5} ions/sec.

  1. INVERSE ELECTRON TRANSFER IN PEROXYOXALATE CHEMIEXCITATION USING EASILY REDUCIBLE ACTIVATORS

    NARCIS (Netherlands)

    Bartoloni, Fernando Heering; Monteiro Leite Ciscato, Luiz Francisco; Augusto, Felipe Alberto; Baader, Wilhelm Josef

    2010-01-01

    INVERSE ELECTRON TRANSFER IN PEROXYOXALATE CHEMIEXCITATION USING EASILY REDUCIBLE ACTIVATORS. Chemiluminescence properties of the peroxyoxalate reaction in the presence of activators bearing electron withdrawing substituents were studied, to evaluate the possible occurrence of an inverse electron tr

  2. INVERSE ELECTRON TRANSFER IN PEROXYOXALATE CHEMIEXCITATION USING EASILY REDUCIBLE ACTIVATORS

    NARCIS (Netherlands)

    Bartoloni, Fernando Heering; Monteiro Leite Ciscato, Luiz Francisco; Augusto, Felipe Alberto; Baader, Wilhelm Josef

    2010-01-01

    INVERSE ELECTRON TRANSFER IN PEROXYOXALATE CHEMIEXCITATION USING EASILY REDUCIBLE ACTIVATORS. Chemiluminescence properties of the peroxyoxalate reaction in the presence of activators bearing electron withdrawing substituents were studied, to evaluate the possible occurrence of an inverse electron tr

  3. INVERSE ELECTRON TRANSFER IN PEROXYOXALATE CHEMIEXCITATION USING EASILY REDUCIBLE ACTIVATORS

    NARCIS (Netherlands)

    Bartoloni, Fernando Heering; Monteiro Leite Ciscato, Luiz Francisco; Augusto, Felipe Alberto; Baader, Wilhelm Josef

    2010-01-01

    INVERSE ELECTRON TRANSFER IN PEROXYOXALATE CHEMIEXCITATION USING EASILY REDUCIBLE ACTIVATORS. Chemiluminescence properties of the peroxyoxalate reaction in the presence of activators bearing electron withdrawing substituents were studied, to evaluate the possible occurrence of an inverse electron

  4. Losses of Superconductor Journal Bearing

    Science.gov (United States)

    Han, Y. H.; Hull, J. R.; Han, S. C.; Jeong, N. H.; Oh, J. M.; Sung, T. H.

    2004-06-01

    A high-temperature superconductor (HTS) journal bearing was studied for rotational loss. Two HTS bearings support the rotor at top and bottom. The rotor weight is 4 kg and the length is about 300 mm. Both the top and bottom bearings have two permanent magnet (PM) rings with an iron pole piece separating them. Each HTS journal bearing is composed of six pieces of superconductor blocks of size 35×25×10 mm. The HTS blocks are encased in a cryochamber through which liquid nitrogen flows. The inner spool of the cryochamber is made from G-10 to reduce eddy current loss, and the rest of the cryochamber is stainless steel. The magnetic field from the PM rings is < 10 mT on the stainless part. The rotational drag was measured over the same speed range at several chamber pressures. Results indicate that a chamber pressure of 0.4 mtorr is sufficiently low to minimize windage loss, and the 10 mT design criterion for the magnetic field on the stainless part of the cryochamber is too high.

  5. The correct "ball bearings" data.

    Science.gov (United States)

    Caroni, C

    2002-12-01

    The famous data on fatigue failure times of ball bearings have been quoted incorrectly from Lieblein and Zelen's original paper. The correct data include censored values, as well as non-fatigue failures that must be handled appropriately. They could be described by a mixture of Weibull distributions, corresponding to different modes of failure.

  6. High performance rolling element bearing

    Science.gov (United States)

    Bursey, Jr., Roger W. (Inventor); Olinger, Jr., John B. (Inventor); Owen, Samuel S. (Inventor); Poole, William E. (Inventor); Haluck, David A. (Inventor)

    1993-01-01

    A high performance rolling element bearing (5) which is particularly suitable for use in a cryogenically cooled environment, comprises a composite cage (45) formed from glass fibers disposed in a solid lubricant matrix of a fluorocarbon polymer. The cage includes inserts (50) formed from a mixture of a soft metal and a solid lubricant such as a fluorocarbon polymer.

  7. Beth Starts Like Brown Bear!

    Science.gov (United States)

    Fawcett, Gay

    1994-01-01

    Recounts a reading teacher's illuminating experience with a first grader who enjoyed reading Bill Martin's "Brown Bear" books, despite being labeled as dyslexic. Dyslexia is an elusive condition that is biological in origin and distinct from other reading problems. New research shows that reading difficulties, including dyslexia, occur as part of…

  8. Control concepts for active magnetic bearings

    Science.gov (United States)

    Siegwart, Roland; Vischer, D.; Larsonneur, R.; Herzog, R.; Traxler, Alfons; Bleuler, H.; Schweitzer, G.

    1992-01-01

    Active Magnetic Bearings (AMB) are becoming increasingly significant for various industrial applications. Examples are turbo-compressors, centrifuges, high speed milling and grinding spindles, vibration isolation, linear guides, magnetically levitated trains, vacuum and space applications. Thanks to the rapid progress and drastic cost reduction in power- and micro-electronics, the number of AMB applications is growing very rapidly. Industrial uses of AMBs leads to new requirements for AMB-actuators, sensor systems, and rotor dynamics. Especially desirable are new and better control concepts to meet demand such as low cost AMB, high stiffness, high performance, high robustness, high damping up to several kHz, vibration isolation, force-free rotation, and unbalance cancellation. This paper surveys various control concepts for AMBs and discusses their advantages and disadvantages. Theoretical and experimental results are presented.

  9. Characterization of Fault Size in Bearings

    Science.gov (United States)

    2014-12-23

    0.3 and 1.2 mm into the outer-race of the bearing, which simulates realistic faults that often can be found in damaged bearings. A 3D dynamic model ...3 4. MODEL DESCRIPTION A 3D dynamic ball bearing model was developed to study the effect of faults on the bearing dynamic behavior. The aim of the...understanding of the effects of fault size on the bearing dynamics. The research methodology combines dynamic modeling of the faulty bearing with

  10. Journal and Wave Bearing Impedance Calculation Software

    Science.gov (United States)

    Hanford, Amanda; Campbell, Robert

    2012-01-01

    The wave bearing software suite is a MALTA application that computes bearing properties for user-specified wave bearing conditions, as well as plain journal bearings. Wave bearings are fluid film journal bearings with multi-lobed wave patterns around the circumference of the bearing surface. In this software suite, the dynamic coefficients are outputted in a way for easy implementation in a finite element model used in rotor dynamics analysis. The software has a graphical user interface (GUI) for inputting bearing geometry parameters, and uses MATLAB s structure interface for ease of interpreting data. This innovation was developed to provide the stiffness and damping components of wave bearing impedances. The computational method for computing bearing coefficients was originally designed for plain journal bearings and tilting pad bearings. Modifications to include a wave bearing profile consisted of changing the film thickness profile given by an equation, and writing an algorithm to locate the integration limits for each fluid region. Careful consideration was needed to implement the correct integration limits while computing the dynamic coefficients, depending on the form of the input/output variables specified in the algorithm.

  11. Health assessment of cooling fan bearings using wavelet-based filtering.

    Science.gov (United States)

    Miao, Qiang; Tang, Chao; Liang, Wei; Pecht, Michael

    2012-12-24

    As commonly used forced convection air cooling devices in electronics, cooling fans are crucial for guaranteeing the reliability of electronic systems. In a cooling fan assembly, fan bearing failure is a major failure mode that causes excessive vibration, noise, reduction in rotation speed, locked rotor, failure to start, and other problems; therefore, it is necessary to conduct research on the health assessment of cooling fan bearings. This paper presents a vibration-based fan bearing health evaluation method using comblet filtering and exponentially weighted moving average. A new health condition indicator (HCI) for fan bearing degradation assessment is proposed. In order to collect the vibration data for validation of the proposed method, a cooling fan accelerated life test was conducted to simulate the lubricant starvation of fan bearings. A comparison between the proposed method and methods in previous studies (i.e., root mean square, kurtosis, and fault growth parameter) was carried out to assess the performance of the HCI. The analysis results suggest that the HCI can identify incipient fan bearing failures and describe the bearing degradation process. Overall, the work presented in this paper provides a promising method for fan bearing health evaluation and prognosis.

  12. Health Assessment of Cooling Fan Bearings Using Wavelet-Based Filtering

    Directory of Open Access Journals (Sweden)

    Qiang Miao

    2012-12-01

    Full Text Available As commonly used forced convection air cooling devices in electronics, cooling fans are crucial for guaranteeing the reliability of electronic systems. In a cooling fan assembly, fan bearing failure is a major failure mode that causes excessive vibration, noise, reduction in rotation speed, locked rotor, failure to start, and other problems; therefore, it is necessary to conduct research on the health assessment of cooling fan bearings. This paper presents a vibration-based fan bearing health evaluation method using comblet filtering and exponentially weighted moving average. A new health condition indicator (HCI for fan bearing degradation assessment is proposed. In order to collect the vibration data for validation of the proposed method, a cooling fan accelerated life test was conducted to simulate the lubricant starvation of fan bearings. A comparison between the proposed method and methods in previous studies (i.e., root mean square, kurtosis, and fault growth parameter was carried out to assess the performance of the HCI. The analysis results suggest that the HCI can identify incipient fan bearing failures and describe the bearing degradation process. Overall, the work presented in this paper provides a promising method for fan bearing health evaluation and prognosis.

  13. Operating procedures, Pilot polar bear survey

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Distance will be measured from the "center" of the sighting (polar bear, group of bears, group of walrus, etc.) to the flight line along a perpendicular projection...

  14. Rolling Element Bearing Stiffness Matrix Determination (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Y.; Parker, R.

    2014-01-01

    Current theoretical bearing models differ in their stiffness estimates because of different model assumptions. In this study, a finite element/contact mechanics model is developed for rolling element bearings with the focus of obtaining accurate bearing stiffness for a wide range of bearing types and parameters. A combined surface integral and finite element method is used to solve for the contact mechanics between the rolling elements and races. This model captures the time-dependent characteristics of the bearing contact due to the orbital motion of the rolling elements. A numerical method is developed to determine the full bearing stiffness matrix corresponding to two radial, one axial, and two angular coordinates; the rotation about the shaft axis is free by design. This proposed stiffness determination method is validated against experiments in the literature and compared to existing analytical models and widely used advanced computational methods. The fully-populated stiffness matrix demonstrates the coupling between bearing radial, axial, and tilting bearing deflections.

  15. Live-trapping and handling brown bear

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — In recent years bears have become increasingly important as big game animals. The brown bears (Ursus middendorfi) on the Kodiak National Wildlife Refuge, Kodiak...

  16. Live-trapping and handling brown bear

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This paper reports techniques developed to live trap and handle brown bears on the Kodiak National Wildlife Refuge. The brown bears (Ursus middendorffi) on the...

  17. Goose Eggs Could Save Polar Bears

    Institute of Scientific and Technical Information of China (English)

    孙淑敏

    2009-01-01

    Polar bears could avoid extinction despitemany starving to death in coming years, ac-cording to scientists and other observers whohave discovered that some of the bears havefound a new food source--goose and duckeggs.

  18. Brown bear telemetry and trapping: Special report

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Brown bear studies were continued during the 1967 field season with emphasis on development of techniques for instrumenting bears with radio transmitters and...

  19. Stable isotopes to detect food-conditioned bears and to evaluate human-bear management

    Science.gov (United States)

    Hopkins, John B.; Koch, Paul L.; Schwartz, Charles C.; Ferguson, Jake M.; Greenleaf, Schuyler S.; Kalinowski, Steven T.

    2012-01-01

    We used genetic and stable isotope analysis of hair from free-ranging black bears (Ursus americanus) in Yosemite National Park, California, USA to: 1) identify bears that consume human food, 2) estimate the diets of these bears, and 3) evaluate the Yosemite human–bear management program. Specifically, we analyzed the isotopic composition of hair from bears known a priori to be food-conditioned or non-food-conditioned and used these data to predict whether bears with an unknown management status were food-conditioned (FC) or non-food-conditioned (NFC). We used a stable isotope mixing model to estimate the proportional contribution of natural foods (plants and animals) versus human food in the diets of FC bears. We then used results from both analyses to evaluate proactive (population-level) and reactive (individual-level) human–bear management, and discussed new metrics to evaluate the overall human–bear management program in Yosemite. Our results indicated that 19 out of 145 (13%) unknown bears sampled from 2005 to 2007 were food-conditioned. The proportion of human food in the diets of known FC bears likely declined from 2001–2003 to 2005–2007, suggesting proactive management was successful in reducing the amount of human food available to bears. In contrast, reactive management was not successful in changing the management status of known FC bears to NFC bears, or in reducing the contribution of human food to the diets of FC bears. Nine known FC bears were recaptured on 14 occasions from 2001 to 2007; all bears were classified as FC during subsequent recaptures, and human–bear management did not reduce the amount of human food in the diets of FC bears. Based on our results, we suggest Yosemite continue implementing proactive human–bear management, reevaluate reactive management, and consider removing problem bears (those involved in repeated bear incidents) from the population.

  20. Advanced Active-Magnetic-Bearing Thrust-Measurement System

    Science.gov (United States)

    Imlach, Joseph; Kasarda, Mary; Blumber, Eric

    2008-01-01

    An advanced thrust-measurement system utilizes active magnetic bearings to both (1) levitate a floating frame in all six degrees of freedom and (2) measure the levitation forces between the floating frame and a grounded frame. This system was developed for original use in measuring the thrust exerted by a rocket engine mounted on the floating frame, but can just as well be used in other force-measurement applications. This system offers several advantages over prior thrust-measurement systems based on mechanical support by flexures and/or load cells: The system includes multiple active magnetic bearings for each degree of freedom, so that by selective use of one, some, or all of these bearings, it is possible to test a given article over a wide force range in the same fixture, eliminating the need to transfer the article to different test fixtures to obtain the benefit of full-scale accuracy of different force-measurement devices for different force ranges. Like other active magnetic bearings, the active magnetic bearings of this system include closed-loop control subsystems, through which the stiffness and damping characteristics of the magnetic bearings can be modified electronically. The design of the system minimizes or eliminates cross-axis force-measurement errors. The active magnetic bearings are configured to provide support against movement along all three orthogonal Cartesian axes, and such that the support along a given axis does not produce force along any other axis. Moreover, by eliminating the need for such mechanical connections as flexures used in prior thrust-measurement systems, magnetic levitation of the floating frame eliminates what would otherwise be major sources of cross-axis forces and the associated measurement errors. Overall, relative to prior mechanical-support thrust-measurement systems, this system offers greater versatility for adaptation to a variety of test conditions and requirements. The basic idea of most prior active-magnetic-bearing

  1. Grease lubrication mechanisms in bearing seals

    OpenAIRE

    2011-01-01

    Rolling bearings contain seals to keep lubricant inside and contaminants outside the bearing system. These systems are often lubricated with grease; the grease acts as a lubricant for the bearing and seal and improves the sealing efficiency. In this thesis, the influence of lubricating grease on bearing seal performance is studied. Rheological properties of the grease, i.e. shear stress and normal stress difference, are evaluated and related to the lubricating and sealing performance of the s...

  2. Thin film superconductor magnetic bearings

    Science.gov (United States)

    Weinberger, Bernard R.

    1995-12-26

    A superconductor magnetic bearing includes a shaft (10) that is subject to a load (L) and rotatable around an axis of rotation, a magnet (12) mounted to the shaft, and a stator (14) in proximity to the shaft. The stator (14) has a superconductor thin film assembly (16) positioned to interact with the magnet (12) to produce a levitation force on the shaft (10) that supports the load (L). The thin film assembly (16) includes at least two superconductor thin films (18) and at least one substrate (20). Each thin film (18) is positioned on a substrate (20) and all the thin films are positioned such that an applied magnetic field from the magnet (12) passes through all the thin films. A similar bearing in which the thin film assembly (16) is mounted on the shaft (10) and the magnet (12) is part of the stator (14) also can be constructed.

  3. Bearing-Mounting Concept Accommodates Thermal Expansion

    Science.gov (United States)

    Nespodzany, Robert; Davis, Toren S.

    1995-01-01

    Pins or splines allow radial expansion without slippage. Design concept for mounting rotary bearing accommodates differential thermal expansion between bearing and any structure(s) to which bearing connected. Prevents buildup of thermal stresses by allowing thermal expansion to occur freely but accommodating expansion in such way not to introduce looseness. Pin-in-slot configuration also maintains concentricity.

  4. Fractal analysis of polar bear hairs

    Directory of Open Access Journals (Sweden)

    Wang Qing-Li

    2015-01-01

    Full Text Available Hairs of a polar bear (Ursus maritimus are of superior properties such as the excellent thermal protection. Why do polar bears can resist such cold environment? The paper concludes that its fractal porosity plays an important role, and its fractal dimensions are very close to the golden mean, 1.618, revealing the possible optimal structure of polar bear hair.

  5. Cryptosporidiosis in a black bear in Virginia.

    Science.gov (United States)

    Duncan, R B; Caudell, D; Lindsay, D S; Moll, H D

    1999-04-01

    Cryptosporidiosis has not been previously reported in black bears in North America, either free-roaming or captive. However, oocysts have been documented in two captive Malayan sun bears (Helarctos malayanus) located in zoological parks in Taiwan. Developmental stages of Cryptosporidium parvum were observed in tissue sections from the small intestine of a black bear cub found dead in Virginia (USA).

  6. Fault Tolerant Homopolar Magnetic Bearings

    Science.gov (United States)

    Li, Ming-Hsiu; Palazzolo, Alan; Kenny, Andrew; Provenza, Andrew; Beach, Raymond; Kascak, Albert

    2003-01-01

    Magnetic suspensions (MS) satisfy the long life and low loss conditions demanded by satellite and ISS based flywheels used for Energy Storage and Attitude Control (ACESE) service. This paper summarizes the development of a novel MS that improves reliability via fault tolerant operation. Specifically, flux coupling between poles of a homopolar magnetic bearing is shown to deliver desired forces even after termination of coil currents to a subset of failed poles . Linear, coordinate decoupled force-voltage relations are also maintained before and after failure by bias linearization. Current distribution matrices (CDM) which adjust the currents and fluxes following a pole set failure are determined for many faulted pole combinations. The CDM s and the system responses are obtained utilizing 1D magnetic circuit models with fringe and leakage factors derived from detailed, 3D, finite element field models. Reliability results are presented vs. detection/correction delay time and individual power amplifier reliability for 4, 6, and 7 pole configurations. Reliability is shown for two success criteria, i.e. (a) no catcher bearing contact following pole failures and (b) re-levitation off of the catcher bearings following pole failures. An advantage of the method presented over other redundant operation approaches is a significantly reduced requirement for backup hardware such as additional actuators or power amplifiers.

  7. Improvement of journal bearing operation at heavy misalignment using bearing flexibility and compliant liners

    DEFF Research Database (Denmark)

    Thomsen, Kim; Klit, Peder

    2012-01-01

    A flexure journal bearing design is proposed that will improve operational behaviour of a journal bearing at pronounced misalignment. Using a thermoelastohydrodynamic model, it is shown that the proposed flexure journal bearing has vastly increased the hydrodynamic performance compared to the stiff...... bearing when misaligned. The hydrodynamic performance is evaluated on lubricant film thickness, pressure and temperature. Furthermore, the influence of a compliant bearing liner is investigated and it is found that it increases the hydrodynamic performance when applied to a stiff bearing, whereas...... the liner has practically no influence on the flexure journal bearing's performance....

  8. Automated Assistance for Designing Active Magnetic Bearings

    Science.gov (United States)

    Imlach, Joseph

    2008-01-01

    MagBear12 is a computer code that assists in the design of radial, heteropolar active magnetic bearings (AMBs). MagBear12 was developed to help in designing the system described in "Advanced Active-Magnetic-Bearing Thrust-Measurement System". Beyond this initial application, MagBear12 is expected to be useful for designing AMBs for a variety of rotating machinery. This program incorporates design rules and governing equations that are also implemented in other, proprietary design software used by AMB manufacturers. In addition, this program incorporates an advanced unpublished fringing-magnetic-field model that increases accuracy beyond that offered by the other AMB-design software.

  9. Shaft Center Orbit in Dynamically Loaded Bearings

    DEFF Research Database (Denmark)

    Klit, Peder

    The aim of this work is to demonstrate how to utilize the bearings damping coefficients to estimate the orbit for a dynamically loaded journal bearing. The classical method for this analysis was developed by Booker in 1965 and described further in 1972. Several authors have refined this method over...... Jorgen W. Lund pointed out in lecture notes that the dynamic damping coefficients of the bearing could be used to find the shaft orbit for dynamically loaded bearings. For simplicity the "Short-Width-Journal-Bearing Theory" is used as a basis for finding the damping coefficients in this work...

  10. Pratt and Whitney cryogenic turbopump bearing experience

    Science.gov (United States)

    Poole, W. E.; Bursey, R. W., Jr.

    1988-01-01

    Successful, reusable bearings require lubrication, traditionally, a transfer film from sacrificial cage wear. Early testing included materials screening programs to identify suitable cryogenic cage materials. A specially developed element tester that simulated the function of a ball bearing cage was used. Suitable materials must provide lubrication with an acceptably low wear rate, without abrading contacting surfaces. The most promising materials were tested in full scale bearings at speeds up to 4 MDN. Teflon, filled with 40 percent bronze powder, was the best performing material. A variety of bearings were designed and successfully tested in LH2 and LOX. Bearings with bronze filled Teflon cages were successfully tested for 150 hrs. In overload tests, the same design was tested for 5 hrs at maximum Hertz stresses above 450 ksi and an additional 5 hrs with a maximum Hertz stress exceeding 500 ksi. Four bearings were tested in LOX for 25 hrs, with a maximum time per bearing of 10 hrs.

  11. Integration of magnetic bearings in the design of advanced gas turbine engines

    Science.gov (United States)

    Storace, Albert F.; Sood, Devendra K.; Lyons, James P.; Preston, Mark A.

    1994-01-01

    Active magnetic bearings provide revolutionary advantages for gas turbine engine rotor support. These advantages include tremendously improved vibration and stability characteristics, reduced power loss, improved reliability, fault-tolerance, and greatly extended bearing service life. The marriage of these advantages with innovative structural network design and advanced materials utilization will permit major increases in thrust to weight performance and structural efficiency for future gas turbine engines. However, obtaining the maximum payoff requires two key ingredients. The first key ingredient is the use of modern magnetic bearing technologies such as innovative digital control techniques, high-density power electronics, high-density magnetic actuators, fault-tolerant system architecture, and electronic (sensorless) position estimation. This paper describes these technologies. The second key ingredient is to go beyond the simple replacement of rolling element bearings with magnetic bearings by incorporating magnetic bearings as an integral part of the overall engine design. This is analogous to the proper approach to designing with composites, whereby the designer tailors the geometry and load carrying function of the structural system or component for the composite instead of simply substituting composites in a design originally intended for metal material. This paper describes methodologies for the design integration of magnetic bearings in gas turbine engines.

  12. Current leads and magnetic bearings

    Science.gov (United States)

    Hull, J. R.

    1993-10-01

    Since the discovery of high temperature superconductors (HTS's), Argonne National Laboratory (ANL) has been active in a broad spectrum of activities in developing these materials for applications. Work at every stage of development has involved industrial collaboration in order to accelerate commercialization. While most of the development work has been devoted to improving the properties of current-carrying wires, some effort has been devoted to applications that can utilize HTS's with properties available now or in the near future. In this paper, advances made in the area of current leads and magnetic bearings are discussed.

  13. Bearing Health Assessment Based on Chaotic Characteristics

    Directory of Open Access Journals (Sweden)

    Chen Lu

    2013-01-01

    Full Text Available Vibration signals extracted from rotating parts of machinery carry a lot of useful information about the condition of operating machine. Due to the strong non-linear, complex and non-stationary characteristics of vibration signals from working bearings, an accurate and reliable health assessment method for bearing is necessary. This paper proposes to utilize the selected chaotic characteristics of vibration signal for health assessment of a bearing by using self-organizing map (SOM. Both Grassberger-Procaccia algorithm and Takens' theory are employed to calculate the characteristic vector which includes three chaotic characteristics, such as correlation dimension, largest Lyapunov exponent and Kolmogorov entropy. After that, SOM is used to map the three corresponding characteristics into a confidence value (CV which represents the health state of the bearing. Finally, a case study based on vibration datasets of a group of testing bearings was conducted to demonstrate that the proposed method can reliably assess the health state of bearing.

  14. Analysis of bearing steel exposed to rolling contact fatigue

    Science.gov (United States)

    Hansen, K. T.; Fæster, S.; Natarajan, A.; Mishin, O. V.; Danielsen, H. K.; Jensen, D. Juul; Klit, P.

    2017-07-01

    The objective of this work is to characterize fatigue damage in roller bearings under conditions of high load and slippage. A test rig constructed for rolling contact fatigue tests of rings is described, and test results are presented for rings taken from two spherical roller bearings. The preparation of the rings and the loading situation are explained. Test conditions are chosen with the aim of achieving pitting formation at the contacting surfaces. During testing the contact pressure, torque and the rotational speed are monitored and recorded. After testing the tested rings have been characterized using X-ray tomography and scanning electron microscopy. The observations confirm that rolling contact fatigue testing at high loads leads to pitting failure at the contacting surfaces. The pitting mostly appears on one side of the contact, attributed to a non-uniform contact pressure in the axial direction.

  15. Analysis of bearing steel exposed to rolling contact fatigue

    DEFF Research Database (Denmark)

    Hansen, K. T.; Fæster, Søren; Natarajan, Anand

    2017-01-01

    The objective of this work is to characterize fatigue damage in roller bearings under conditions of high load and slippage. A test rig constructed for rolling contact fatigue tests of rings is described, and test results are presented for rings taken from two spherical roller bearings....... The preparation of the rings and the loading situation are explained. Test conditions are chosen with the aim of achieving pitting formation at the contacting surfaces. During testing the contact pressure, torque and the rotational speed are monitored and recorded. After testing the tested rings have been...... characterized using X-ray tomography and scanning electron microscopy. The observations confirm that rolling contact fatigue testing at high loads leads to pitting failure at the contacting surfaces. The pitting mostly appears on one side of the contact, attributed to a non-uniform contact pressure in the axial...

  16. Powder-Metallurgical Bearings For Turbopumps

    Science.gov (United States)

    Bhat, B. N.; Humphries, T. S.; Thom, R. L.; Moxson, V.; Friedman, G. I.; Dolan, F. J.; Shipley, R. J.

    1993-01-01

    Bearings fabricated by powder metallurgy developed for use in machines subjected to extremes of temperature, rolling-contact cyclic stresses, and oxidizing or otherwise corrosive fluids. Bearings also extend operating lives of other machines in which bearings required to resist extreme thermal, mechanical, and chemical stresses. One alloy exhibiting outstanding properties was MRC-2001. Resistance to fatigue, stress corrosion cracking, and wear found superior to that of 440C stainless steel.

  17. Electromechanical properties of radial active magnetic bearings

    OpenAIRE

    Antila, Matti

    1998-01-01

    Nonideal properties of the electromagnetic actuators in radial active magnetic bearings are studied. The two dimensional nonlinear stationary finite element method is used to determine the linearised parameters of a radial active magnetic bearing. The method is verified on two test machines. The accuracy is 10-15 % in the magnetic saturation region. The effect of magnetic saturation on the bearing dynamics is studied based on the root locus diagrams of the closed loop system. These diagrams s...

  18. Are organohalogen contaminants a bears (Ursus maritimus)?

    DEFF Research Database (Denmark)

    Sonne, Christian; Dietz, Rune; Leifsson, PS

    2006-01-01

    Tissues of polar bears (Ursus maritimus) from East Greenland contain the highest concentrations of organohalogen contaminants (OHCs) among subpopulations of any mammalian species in the Arctic. Negative associations also have been found between OHC concentrations and bone mineral density and liver...... histology parameters for this subpopulation of polar bears. The present study examined the OHC concentrations and adverse effects on renal tissue for 75 polar bears collected during 1999 to 2002. Specific lesions were diffuse glomerular capillary wall thickening, mesangial glomerular deposits, tubular...

  19. Axial force calculation of passive magnetic bearing

    National Research Council Canada - National Science Library

    Vučković Ana N; Raičević Nebojša B; Ilić Saša S; Aleksić Slavoljub R; Perić Mirjana T

    2014-01-01

    .... Configuration like this one resembles the one passive magnetic bearing has. Force calculation is performed using semi analytical approach based on fictitious magnetization charges and discretization technique...

  20. Permanent Magnetic Bearing for Spacecraft Applications

    Science.gov (United States)

    Morales, Winfredo; Fusaro, Robert; Kascak, Albert

    2008-01-01

    A permanent, totally passive magnetic bearing rig was designed, constructed, and tested. The suspension of the rotor was provided by two sets of radial permanent magnetic bearings operating in the repulsive mode. The axial support was provided by jewel bearings on both ends of the rotor. The rig was successfully operated to speeds of 5500 rpm using an air impeller. Radial and axial stiffnesses of the permanent magnetic bearings were experimentally measured and then compared to finite element results. The natural damping of the rotor was measured and a damping coefficient was calculated.

  1. Prospects for P-bearing molecules in cometary atmospheres

    Science.gov (United States)

    Boice, Daniel; de Almeida, Amaury

    Phosphorus is a key element in all known forms of life and phosphorus-bearing compounds have been observed in space. Phosphorus is ubiquitous in meteorites, albeit in small quantities, with phosphates being found in stoney meteorites and phosphides have been identified in iron meteorites. It has been detected as part of the dust component in comet Halley but searches for P-bearing species in the gas phase in comets have been unsuccessful. Based of its moderate cosmic abundance (eighteenth most abundant element, [P]/[N] = 4 x 10-3 ) and the positive identification of P-bearing species in the interstellar medium (such as, PN, PC, HCP and PO), we would expect simple molecules, diatomics (like PH, PO, PC, PS), triatomics (like HCP and PH2 ), and possibly other polyatomics (like phosphine PH3 and diphosphine P2 H4 ), to exist in cometary ices, hence released into the gas phase upon ice sublimation. Our fluid dynamics model with chemistry of cometary comae (SUISEI) has been adapted to study this problem. SUISEI produces cometocentric abundances of the coma gas species; velocities of the bulk gas, light atomic and molecular hydrogen with escape, and electrons; gas and electron temperatures; column densities to facilitate comparison with observations; coma energy budget quantities; attenuation of the solar irradiance; and other quantities that can be related readily to observations. We present results from the first quantitative study of phosphorus-bearing molecules in comets to identify likely species containing phosphorus to aid in future searches for this important element in comets, possibly shedding light on issues of comet formation (time and place) and matters of the prebiotic to biotic evolution of life. Acknowledgements. This work was supported by the NSF Planetary Astronomy Program.

  2. Antimicrobial Cu-bearing stainless steel scaffolds.

    Science.gov (United States)

    Wang, Qiang; Ren, Ling; Li, Xiaopeng; Zhang, Shuyuan; Sercombe, Timothy B; Yang, Ke

    2016-11-01

    Copper-bearing stainless steel scaffolds with two different structures (Body Centered Cubic and Gyroid labyrinth) at two solid fractions (25% and 40%) were fabricated from both 316L powder and a mixture of 316L and elemental Cu powder using selective laser melting, and relative 316L scaffolds were served as control group. After processing, the antimicrobial testing demonstrated that the 316L-Cu scaffolds presented excellent antimicrobial activity against Escherichia coli and Staphylococcus aureus, and the cell viability assay indicated that there was no cytotoxic effect of 316L-Cu scaffolds on rat marrow mesenchymal stem cells. As such, these have the potential to reduce implant-associated infections. The Cu was also found to homogeneously distribute within the microstructure by scanning electronic microcopy. The addition of Cu would not significantly affect its strength and stiffness compared to 316L scaffold, and the stiffness of all the scaffolds (3-20GPa) is similar to that of bone and much less than that of bulk stainless steel. Consequently, fabrication of such low stiffness porous structures, especially coupled with the addition of antimicrobial Cu, may provide a new direction for medical stainless steels.

  3. Gearbox Reliability Collaborative Bearing Calibration

    Energy Technology Data Exchange (ETDEWEB)

    van Dam, J.

    2011-10-01

    NREL has initiated the Gearbox Reliability Collaborative (GRC) to investigate the root cause of the low wind turbine gearbox reliability. The GRC follows a multi-pronged approach based on a collaborative of manufacturers, owners, researchers and consultants. The project combines analysis, field testing, dynamometer testing, condition monitoring, and the development and population of a gearbox failure database. At the core of the project are two 750kW gearboxes that have been redesigned and rebuilt so that they are representative of the multi-megawatt gearbox topology currently used in the industry. These gearboxes are heavily instrumented and are tested in the field and on the dynamometer. This report discusses the bearing calibrations of the gearboxes.

  4. Evaluation of bearing configurations using the single bearing tester in liquid nitrogen

    Science.gov (United States)

    Jett, T.; Hall, P.; Thom, R.

    1991-01-01

    Various bearing configurations were tested using the Marshall Space Flight Center single bearing tester with LN2 as the cryogenic coolant. The baseline was one Rocketdyne phase one high pressure oxidizer turbopump (HPOTP) pump end 45-mm bore bearing. The bearing configurations that were tested included a Salox/M cage configuration, a silicon nitride ball configuration, an elongated cage configuration, and a Bray 601 grease configuration.

  5. Rotor-Bearing Dynamics Technology Design Guide. Part 4. Cylindrical Roller Bearings

    Science.gov (United States)

    1979-12-01

    ýbluck ,,lb.,mb i Tapered Roller Bearings Roller Beating Stiffness Tapered Roller Bearing Stiffness Turbine Bearings VRoller Bearings Rotordynamics ...input for rotordynamic response programs. The complete stiffness matrix is calculated including centrifugal effects. Considerations such as elastohydro...those parts directly connected with preparation of input for the rotordynamic response programs (Part 1(5) of the revised series) were retained. The

  6. State Space Formulation of Nonlinear Vibration Responses Collected from a Dynamic Rotor-Bearing System: An Extension of Bearing Diagnostics to Bearing Prognostics

    Directory of Open Access Journals (Sweden)

    Peter W. Tse

    2017-02-01

    Full Text Available Bearings are widely used in various industries to support rotating shafts. Their failures accelerate failures of other adjacent components and may cause unexpected machine breakdowns. In recent years, nonlinear vibration responses collected from a dynamic rotor-bearing system have been widely analyzed for bearing diagnostics. Numerous methods have been proposed to identify different bearing faults. However, these methods are unable to predict the future health conditions of bearings. To extend bearing diagnostics to bearing prognostics, this paper reports the design of a state space formulation of nonlinear vibration responses collected from a dynamic rotor-bearing system in order to intelligently predict bearing remaining useful life (RUL. Firstly, analyses of nonlinear vibration responses were conducted to construct a bearing health indicator (BHI so as to assess the current bearing health condition. Secondly, a state space model of the BHI was developed to mathematically track the health evolution of the BHI. Thirdly, unscented particle filtering was used to predict bearing RUL. Lastly, a new bearing acceleration life testing setup was designed to collect natural bearing degradation data, which were used to validate the effectiveness of the proposed bearing prognostic method. Results show that the prediction accuracy of the proposed bearing prognostic method is promising and the proposed bearing prognostic method is able to reflect future bearing health conditions.

  7. Fault diagnosis of the rolling bearing with optical fiber Bragg grating vibration sensor

    Science.gov (United States)

    Wei, Peng; Dai, Zejing; Zheng, Leilei; Li, Ming

    2016-10-01

    Fault diagnosis of the rolling bearing means a lot for property and life safety. In this paper the Fiber Bragg Grating (FBG) vibration sensor and resonance demodulation technology are used in the fault diagnosis of the rolling bearing. Traditionally, the vibration signals are measured by the resistance strain gauge, accelerometer, etc. But those traditional electronic sensors are usually influenced by the industry electromagnetic noise. But the FBG vibration sensor is totally different. It has a lot of advantages such as small volume, light weight, easy connection and so on. And the high industry electromagnetic noise means nothing to the FBG sensors. In this paper, we use the FBG vibration and temperature sensors to measure the fast strain and temperature signal of the rolling bearing. In order to extract the fault signals from strong background noise, the resonant demodulation technology is used to analyze and process the vibration signals collected by the FBG sensors. In order to verify the reliability of the FBG vibration sensor and resonance demodulation technology applied in the fault diagnosis of the rolling bearing, several experiments are done. Five FBG vibration sensors are attached on the different parts of the rolling bearing to verify its function and its influence on the fault diagnosis of the rolling bearing. The results of the experiments show that the FBG vibration sensor method could be used in fault diagnosis of the rolling bearing. The repetitive experiments show the reliability of the FBG vibration sensors method.

  8. 14 CFR 23.623 - Bearing factors.

    Science.gov (United States)

    2010-01-01

    ... Bearing factors. (a) Each part that has clearance (free fit), and that is subject to pounding or vibration, must have a bearing factor large enough to provide for the effects of normal relative motion. (b) For control surface hinges and control system joints, compliance with the factors prescribed in §§ 23.657 and...

  9. Precision instrumentation for rolling element bearing characterization

    Science.gov (United States)

    Marsh, Eric R.; Vigliano, Vincent C.; Weiss, Jeffrey R.; Moerlein, Alex W.; Vallance, R. Ryan

    2007-03-01

    This article describes an instrument to measure the error motion of rolling element bearings. This challenge is met by simultaneously satisfying four requirements. First, an axial preload must be applied to seat the rolling elements in the bearing races. Second, one of the races must spin under the influence of an applied torque. Third, rotation of the remaining race must be prevented in a way that leaves the radial, axial/face, and tilt displacements free to move. Finally, the bearing must be fixtured and measured without introducing off-axis loading or other distorting influences. In the design presented here, an air bearing reference spindle with error motion of less than 10 nm rotates the inner race of the bearing under test. Noninfluencing couplings are used to prevent rotation of the bearing outer race and apply an axial preload without distorting the bearing or influencing the measurement. Capacitive displacement sensors with 2 nm resolution target the nonrotating outer race. The error motion measurement repeatability is shown to be less than 25 nm. The article closes with a discussion of how the instrument may be used to gather data with sufficient resolution to accurately estimate the contact angle of deep groove ball bearings.

  10. Can polar bear hairs absorb environmental energy?

    Directory of Open Access Journals (Sweden)

    He Ji-Huan

    2011-01-01

    Full Text Available A polar bear (Ursus maritimus has superior ability to survive in harsh Arctic regions, why does the animal have such an excellent thermal protection? The present paper finds that the unique labyrinth cavity structure of the polar bear hair plays an important role. The hair can not only prevent body temperature loss but can also absorb energy from the environment.

  11. Can polar bear hairs absorb environmental energy?

    OpenAIRE

    He Ji-Huan; Wang Qing-Li; Sun Jie

    2011-01-01

    A polar bear (Ursus maritimus) has superior ability to survive in harsh Arctic regions, why does the animal have such an excellent thermal protection? The present paper finds that the unique labyrinth cavity structure of the polar bear hair plays an important role. The hair can not only prevent body temperature loss but can also absorb energy from the environment.

  12. Movie Director Bags a Silver Bear

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Chinese director and film writer Wang Xiaoshuai has walked away with the Silver Bear award at the 58th Berlin International Film Festival for best script of Zuo You, or In Love We Trust. Back in 2001, Wang won his first Silver Bear award for directing Beijing

  13. Shaft Center Orbit in Dynamically Loaded Bearings

    DEFF Research Database (Denmark)

    Klit, Peder

    2005-01-01

    The aim of this work is to demonstrate how to utilize the bearings damping coe±cients to estimate the orbit for a dynamically loaded journal bearing. The classical method for this analysis was developed by Booker in 1965 [1]and described further in 1972 [2]. Several authors have re¯ned this method...... seventies Jorgen W. Lund pointed out in lecture notes that the dynamic damping coe±cients of the bearing could be used to ¯nd the shaft orbit for dynamically loaded bearings. For simplicity the "Short-Width-Journal-Bearing Theory" is used as a basis for ¯nding the damping coe±cients in this work...

  14. Trends in Controllable Oil Film Bearings

    DEFF Research Database (Denmark)

    Santos, Ilmar

    2011-01-01

    This work gives an overview about the theoretical and experimental achievements of mechatronics applied to oil film bearings, with the aim of: controlling the lateral vibration of flexible rotating shafts; modifying bearing dynamic characteristics, as stiffness and damping properties; increasing...... the rotational speed ranges by improving damping and eliminating instability problems, for example, by compensating cross-coupling destabilizing effects; reducing startup torque and energy dissipation in bearings; compensating thermal effects. It is shown that such controllable bearings can act as "smart......" components and be applied to rotating machines with the goal of avoiding unexpected stops of plants, performing rotordynamic tests and identifying model parameters "on site". Emphasis is given to the controllable lubrication (active lubrication) applied to different types of oil film bearings, i...

  15. 77 FR 33230 - Notice of Intent To Prepare an Environmental Impact Statement for Proposed Strategies for Lake...

    Science.gov (United States)

    2012-06-05

    ...), recreation, fishing, cultural resources, socioeconomic conditions, grizzly bears, aquatic birds... seq.), and is in the exercise of authority delegated to the Assistant Secretary--Indian Affairs,...

  16. Geology and geomorphology of Bear Lake Valley and upper Bear River, Utah and Idaho

    Science.gov (United States)

    Reheis, M.C.; Laabs, B.J.C.; Kaufman, D.S.

    2009-01-01

    Bear Lake, on the Idaho-Utah border, lies in a fault-bounded valley through which the Bear River flows en route to the Great Salt Lake. Surficial deposits in the Bear Lake drainage basin provide a geologic context for interpretation of cores from Bear Lake deposits. In addition to groundwater discharge, Bear Lake received water and sediment from its own small drainage basin and sometimes from the Bear River and its glaciated headwaters. The lake basin interacts with the river in complex ways that are modulated by climatically induced lake-level changes, by the distribution of active Quaternary faults, and by the migration of the river across its fluvial fan north of the present lake. The upper Bear River flows northward for ???150 km from its headwaters in the northwestern Uinta Mountains, generally following the strike of regional Laramide and late Cenozoic structures. These structures likely also control the flow paths of groundwater that feeds Bear Lake, and groundwater-fed streams are the largest source of water when the lake is isolated from the Bear River. The present configuration of the Bear River with respect to Bear Lake Valley may not have been established until the late Pliocene. The absence of Uinta Range-derived quartzites in fluvial gravel on the crest of the Bear Lake Plateau east of Bear Lake suggests that the present headwaters were not part of the drainage basin in the late Tertiary. Newly mapped glacial deposits in the Bear River Range west of Bear Lake indicate several advances of valley glaciers that were probably coeval with glaciations in the Uinta Mountains. Much of the meltwater from these glaciers may have reached Bear Lake via groundwater pathways through infiltration in the karst terrain of the Bear River Range. At times during the Pleistocene, the Bear River flowed into Bear Lake and water level rose to the valley threshold at Nounan narrows. This threshold has been modified by aggradation, downcutting, and tectonics. Maximum lake

  17. A Hybrid Nonlinear Control Scheme for Active Magnetic Bearings

    Science.gov (United States)

    Xia, F.; Albritton, N. G.; Hung, J. Y.; Nelms, R. M.

    1996-01-01

    A nonlinear control scheme for active magnetic bearings is presented in this work. Magnet winding currents are chosen as control inputs for the electromechanical dynamics, which are linearized using feedback linearization. Then, the desired magnet currents are enforced by sliding mode control design of the electromagnetic dynamics. The overall control scheme is described by a multiple loop block diagram; the approach also falls in the class of nonlinear controls that are collectively known as the 'integrator backstepping' method. Control system hardware and new switching power electronics for implementing the controller are described. Various experiments and simulation results are presented to demonstrate the concepts' potentials.

  18. A multifunctional load-bearing solid-state supercapacitor.

    Science.gov (United States)

    Westover, Andrew S; Tian, John W; Bernath, Shivaprem; Oakes, Landon; Edwards, Rob; Shabab, Farhan N; Chatterjee, Shahana; Anilkumar, Amrutur V; Pint, Cary L

    2014-06-11

    A load-bearing, multifunctional material with the simultaneous capability to store energy and withstand static and dynamic mechanical stresses is demonstrated. This is produced using ion-conducting polymers infiltrated into nanoporous silicon that is etched directly into bulk conductive silicon. This device platform maintains energy densities near 10 W h/kg with Coulombic efficiency of 98% under exposure to over 300 kPa tensile stresses and 80 g vibratory accelerations, along with excellent performance in other shear, compression, and impact tests. This demonstrates performance feasibility as a structurally integrated energy storage material broadly applicable across renewable energy systems, transportation systems, and mobile electronics, among others.

  19. THE STRUCTURAL ANALYSIS OF STEEL SILOS WITH CYLINDRICAL-WALL BEARING AND PROFILE-STEEL BEARING

    Directory of Open Access Journals (Sweden)

    Zhengjun Tang

    2015-04-01

    Full Text Available The silos are widely used in bulk material in many fields such as agriculture, mining, chemical, electric power storage, etc. Thin metal cylindrical silo shells are vulnerable to buckling failure caused by the compressive wall friction force. In this paper, the structural analysis of two types of steel silo with cylindrical-wall bearing and profile-steel bearing is implemented by Abaqus finite element analysis. The results indicate that under the same loading conditions, steel silos with profile-steel bearing and cylindrical-Wall bearing have similar values in Mises stress, but the steel silo with profile-steel bearing has a smaller radial displacement and a better capability of buckling resistance. Meanwhile, the total steel volumes reduced 8.0% comparing to the steel silo with cylindrical-wall bearing. Therefore, steel soil with profile-steel bearing not only has a less steel volumes but also a good stability.

  20. Radiation tolerance in water bears.

    Science.gov (United States)

    Horikawa, D. D.; Sakashita, T.; Katagiri, C.; Watanabe, M.; Nakahara, Y.; Okuda, T.; Hamada, N.; Wada, S.; Funayama, T.; Kobayashi, Y.

    Tardigrades water bears are tiny invertebrates forming a phylum and inhabit various environments on the earth Terrestrial tardigrades enter a form called as anhydrobiosis when the surrounding water disappears Anhyydrobiosis is defined as an ametabolic dry state and followed by recovering their activity when rehydrated Anhydrobiotic tardigrades show incredible tolerance to a variety of extreme environmental conditions such as temperatures -273 r C to 151 r C vacuum high pressure 600 MPa and chemicals that include alcohols and methyl bromide In these views there have been some discussions about their potential for surviving outer space In the present study we demonstrated the survival limit not merely against gamma-rays but against heavy ions in the tardigrade Milnesium tardigradum in order to evaluate the effects of radiations on them The animals were exposure to 500 to 7000 Gy of gamma-rays or 500 to 8000 Gy of heavy ions 4 He in their hydrated or anhydrobiotic state The results showed that both of hydrated and anhydrobiotic animals have high radio-tolerance median lethal dose LD50 48 h of gamma-rays or heavy ions in M tardigradum was more than 4000 Gy indicating that this species is categorized into the most radio-tolerant animals We suggest that tardigrades will be suitable model animals for extremophilic multicellular organisms and may provide a survival strategy in extraterrestrial environments

  1. Electronics and electronic systems

    CERN Document Server

    Olsen, George H

    1987-01-01

    Electronics and Electronic Systems explores the significant developments in the field of electronics and electronic devices. This book is organized into three parts encompassing 11 chapters that discuss the fundamental circuit theory and the principles of analog and digital electronics. This book deals first with the passive components of electronic systems, such as resistors, capacitors, and inductors. These topics are followed by a discussion on the analysis of electronic circuits, which involves three ways, namely, the actual circuit, graphical techniques, and rule of thumb. The remaining p

  2. Minimization and identification of conducted emission bearing current in variable speed induction motor drives using PWM inverter

    Indian Academy of Sciences (India)

    A Ramachandran; M Channa Reddy; Ranjan Moodithaya

    2008-10-01

    The recent increase in the use of speed control of ac induction motor for variable speed drive using pulse width modulation (PWM) inverter is due to the advent of modern power electronic devices and introduction of microprocessors. There are many advantages of using ac induction motor for speed control applicatons in process and aerospace industries, but due to fast switching of the modern power electronic devices, the parasitic coupling produces undesirable effects. The undesirable effects include radiated and conducted electromagnetic interference (EMI) which adversely affect nearby computers, electronic/electrical instruments and give rise to the flow of bearing current in the induction motor. Due to the flow of bearing current in the induction motor, electrical discharge machining takes place in the inner race of the bearing which reduces the life of the bearing. In high power converters and inverters, the conducted and radiated emissions become a major concern. In this paper, identification of bearing current due to conducted emission, the measurement of bearing current in a modified induction motor and to minimize the bearing current are discussed. The standard current probe, the standard line impedance stabilization network (LISN)), the electronics interface circuits are used to measure high frequency common mode current, bearing current and to minimize the conducted noise from the system. The LISN will prevent the EMI noise entering the system from the supply source by conductive methods, at the same time prevents the EMI generated if any due to PWM, fast switching in the system, will not be allowed to enter the supply line. For comparing the results with Federal Communications Commission (FCC) and Special Committee on Radio Interference (CISPR) standards, the graphs are plotted with frequency Vs, line voltage in $dB{_\\mu} V$, common mode voltage in $dB{_\\mu} V$ and the bearing current in $dB_{\\mu} A$ with out and with minimizing circuits.

  3. Polar bears and sea ice habitat change

    Science.gov (United States)

    Durner, George M.; Atwood, Todd C.; Butterworth, Andy

    2017-01-01

    The polar bear (Ursus maritimus) is an obligate apex predator of Arctic sea ice and as such can be affected by climate warming-induced changes in the extent and composition of pack ice and its impacts on their seal prey. Sea ice declines have negatively impacted some polar bear subpopulations through reduced energy input because of loss of hunting habitats, higher energy costs due to greater ice drift, ice fracturing and open water, and ultimately greater challenges to recruit young. Projections made from the output of global climate models suggest that polar bears in peripheral Arctic and sub-Arctic seas will be reduced in numbers or become extirpated by the end of the twenty-first century if the rate of climate warming continues on its present trajectory. The same projections also suggest that polar bears may persist in the high-latitude Arctic where heavy multiyear sea ice that has been typical in that region is being replaced by thinner annual ice. Underlying physical and biological oceanography provides clues as to why polar bear in some regions are negatively impacted, while bears in other regions have shown no apparent changes. However, continued declines in sea ice will eventually challenge the survival of polar bears and efforts to conserve them in all regions of the Arctic.

  4. Passive Magnetic Bearing With Ferrofluid Stabilization

    Science.gov (United States)

    Jansen, Ralph; DiRusso, Eliseo

    1996-01-01

    A new class of magnetic bearings is shown to exist analytically and is demonstrated experimentally. The class of magnetic bearings utilize a ferrofluid/solid magnet interaction to stabilize the axial degree of freedom of a permanent magnet radial bearing. Twenty six permanent magnet bearing designs and twenty two ferrofluid stabilizer designs are evaluated. Two types of radial bearing designs are tested to determine their force and stiffness utilizing two methods. The first method is based on the use of frequency measurements to determine stiffness by utilizing an analytical model. The second method consisted of loading the system and measuring displacement in order to measure stiffness. Two ferrofluid stabilizers are tested and force displacement curves are measured. Two experimental test fixtures are designed and constructed in order to conduct the stiffness testing. Polynomial models of the data are generated and used to design the bearing prototype. The prototype was constructed and tested and shown to be stable. Further testing shows the possibility of using this technology for vibration isolation. The project successfully demonstrated the viability of the passive magnetic bearing with ferrofluid stabilization both experimentally and analytically.

  5. Space Telescope Fine Guidance Sensor Bearing Anomaly

    Science.gov (United States)

    Loewenthal, S.; Esper, J.; Pan, J.; Decker, J.

    1996-01-01

    Early in 1993, a servo motor within one of three Fine Guidance Sensors (FGS) aboard the Hubble Space Telescope (HST) reached stall torque levels on several occasions. Little time was left to plan replacement during the first servicing mission, scheduled at the end of '93. Accelerated bearing life tests confirmed that a small angle rocking motion, known as Coarse Track (CT), accelerated bearing degradation. Saturation torque levels were reached after approximately 20 million test cycles, similar to the flight bearings. Reduction in CT operation, implemented in flight software, extended FGS life well beyond the first servicing mission. However in recent years, bearing torques have resumed upward trends and together with a second, recent bearing torque anomaly has necessitated a scheduled FGS replacement during the upcoming second servicing mission in '97. The results from two series of life tests to quantify FGS bearing remaining life, discussion of bearing on-orbit performance, and future plans to service the FGS servos are presented in this paper.

  6. Genomic sequencing of Pleistocene cave bears

    Energy Technology Data Exchange (ETDEWEB)

    Noonan, James P.; Hofreiter, Michael; Smith, Doug; Priest, JamesR.; Rohland, Nadin; Rabeder, Gernot; Krause, Johannes; Detter, J. Chris; Paabo, Svante; Rubin, Edward M.

    2005-04-01

    Despite the information content of genomic DNA, ancient DNA studies to date have largely been limited to amplification of mitochondrial DNA due to technical hurdles such as contamination and degradation of ancient DNAs. In this study, we describe two metagenomic libraries constructed using unamplified DNA extracted from the bones of two 40,000-year-old extinct cave bears. Analysis of {approx}1 Mb of sequence from each library showed that, despite significant microbial contamination, 5.8 percent and 1.1 percent of clones in the libraries contain cave bear inserts, yielding 26,861 bp of cave bear genome sequence. Alignment of this sequence to the dog genome, the closest sequenced genome to cave bear in terms of evolutionary distance, revealed roughly the expected ratio of cave bear exons, repeats and conserved noncoding sequences. Only 0.04 percent of all clones sequenced were derived from contamination with modern human DNA. Comparison of cave bear with orthologous sequences from several modern bear species revealed the evolutionary relationship of these lineages. Using the metagenomic approach described here, we have recovered substantial quantities of mammalian genomic sequence more than twice as old as any previously reported, establishing the feasibility of ancient DNA genomic sequencing programs.

  7. Journal bearing impedance descriptions for rotordynamic applications

    Science.gov (United States)

    Childs, D.; Moes, H.; Van Leeuwen, H.

    1976-01-01

    The paper deals with the development of analytic descriptions for plain circumferentially-symmetric fluid journal bearings, which are suitable for use in rotor dynamic analysis. The bearing impedance vector is introduced, which defines the bearing reaction force components as a function of the bearing motion. Impedances are derived directly for the Ocvirk (short) and Sommerfeld (long) bearings, and the relationships between the impedance vector and the more familiar mobility vector are developed and used to derive analytic impedance for finite-length bearings. The static correctness of the finite-length cavitating impedance is verified. Analytic stiffness and damping coefficient definitions are derived in terms of an impedance vector for small motion around an equilibrium position and demonstrated for the finite-length cavitating impedance. Nonlinear transient rotordynamic simulations are presented for the short pi and 2-pi impedances and the finite-length cavitating impedance. It is shown that finite-length impedance yields more accurate results for substantially less computer time than the short-bearing numerical-pressure-integration approach.

  8. Active magnetic bearings - a step towards smart rotating machinery

    Energy Technology Data Exchange (ETDEWEB)

    Nordmann, R.; Aenis, M.; Knopf, E.; Strassburger, S. [Darmstadt Univ. of Technology, Darmstadt (Germany)

    2000-07-01

    In the field of rotating machinery the number of applications of rotating systems running in active magnetic bearings (AMB's) is increasing. In comparison to conventional bearings magnetic bearings are a typical mechatronic product consisting of mechanical, electrical and electronic components. Such systems have the ability to pick up changes in its environment by sensors and to react to the system or process by means of actuators after an appropriate information processing carried out in a microprocessor. Nowadays, rotors in active magnetic bearings already offer a variety of advantages compared to conventional systems. Some of them are the tuning possibilities for stiffness and damping, the absence of friction and wear, the high running speeds, the vibration isolation and possible unbalance compensation, However, there is much more potential in such systems with respect to a smart behavior. With the mechatronic structure of a rotating machinery in AMB's consisting of built-in control, sensors, microprocessors, actuators and last but not least built-in software different novel features like identification, diagnosis, prognosis and correction can be realised. In this way it will be possible to design new machines with higher performance, higher reliability and a longer lifetime. This paper particularly describes a Smart Machine Technology for rotating machines with AMB's and concentrates on the mentioned smart features of identification, diagnosis and correction. After a general description of the smart technology followed by a presentation of the necessary development tools three applications will show the usefulness of this new technology. (Author)

  9. Geomaterials related to photovoltaics: a nanostructured Fe-bearing kuramite, Cu3SnS4

    Science.gov (United States)

    Di Benedetto, Francesco; Bencistà, Ilaria; D'Acapito, Francesco; Frizzera, Silvia; Caneschi, Andrea; Innocenti, Massimo; Lavacchi, Alessandro; Montegrossi, Giordano; Oberhauser, Werner; Romanelli, Maurizio; Dittrich, Herbert; Pardi, Luca A.; Tippelt, Gerold; Amthauer, Georg

    2016-09-01

    The successful synthesis of nanoparticles of Fe-bearing kuramite, (Cu,Fe)3SnS4, is reported in this study. Nanocrystalline powders were obtained through a mild, environmentally friendly and scalable solvothermal approach, in a single run. The sample was the object of a multidisciplinary investigation, including X-ray diffraction and absorption, scanning electron microscopy and microanalysis, electron paramagnetic resonance, diffuse reflectance and Mössbauer spectroscopy as well as SQUID magnetometry. The nanoparticles consist of pure Fe-bearing kuramite, exhibiting tetragonal structure. The valence state of the metal cations was assessed to be Cu+, Sn4+ and Fe3+. The material presents a band gap value of 1.6 eV, which is fully compatible with solar cell applications. The uptake of Fe by nanokuramite opens a compositional field where the physical properties can be tuned. We thus foster the application of Fe-bearing nanokuramite for photovoltaics and energy storage purposes.

  10. Failure Analysis and Thermochemical Surface Engineering of Bearings in the Wind Turbine Drivetrain

    DEFF Research Database (Denmark)

    West, Ole H.E.; Dahl, Kristian Vinter; Christiansen, Thomas Lundin

    A critical premature failure mode of rolling element bearings inside the wind turbine drivetrain is associated with the formation of so called white etching cracks (WECs). So far there is no consensus on the root cause of WEC failure and the exact influence of different drivers and their combinat......A critical premature failure mode of rolling element bearings inside the wind turbine drivetrain is associated with the formation of so called white etching cracks (WECs). So far there is no consensus on the root cause of WEC failure and the exact influence of different drivers...... and their combinations is not well understood. Various types of failed rolling element bearings from different positions inside the wind turbine drivetrain were investigated. Both conventional techniques as reflected light microscopy (RLM), scanning (SEM) and transmission (TEM) electron microscopy as well as electron...

  11. Genetics Home Reference: Beare-Stevenson cutis gyrata syndrome

    Science.gov (United States)

    ... Health Conditions Beare-Stevenson cutis gyrata syndrome Beare-Stevenson cutis gyrata syndrome Enable Javascript to view the ... Download PDF Open All Close All Description Beare-Stevenson cutis gyrata syndrome is a genetic disorder characterized ...

  12. Active magnetic bearings applied to industrial compressors

    Science.gov (United States)

    Kirk, R. G.; Hustak, J. F.; Schoeneck, K. A.

    1993-01-01

    The design and shop test results are given for a high-speed eight-stage centrifugal compressor supported by active magnetic bearings. A brief summary of the basic operation of active magnetic bearings and the required rotor dynamics analysis are presented with specific attention given to design considerations for optimum rotor stability. The concerns for retrofits of magnetic bearings in existing machinery are discussed with supporting analysis of a four-stage centrifugal compressor. The current status of industrial machinery in North America using this new support system is presented and recommendations are given on design and analysis requirements for successful machinery operation of either retrofit or new design turbomachinery.

  13. Hydrostatic, aerostatic and hybrid bearing design

    CERN Document Server

    Rowe, W Brian

    2012-01-01

    Solve your bearing design problems with step-by-step procedures and hard-won performance data from a leading expert and consultant Compiled for ease of use in practical design scenarios, Hydrostatic, Aerostatic and Hybrid Bearing Design provides the basic principles, design procedures and data you need to create the right bearing solution for your requirements. In this valuable reference and design companion, author and expert W. Brian Rowe shares the hard-won lessons and figures from a lifetime's research and consultancy experience. Coverage includes: Clear e

  14. Microeconomic analysis of military aircraft bearing restoration

    Science.gov (United States)

    Hein, G. F.

    1976-01-01

    The risk and cost of a bearing restoration by grinding program was analyzed. A microeconomic impact analysis was performed. The annual cost savings to U.S. Army aviation is approximately $950,000.00 for three engines and three transmissions. The capital value over an indefinite life is approximately ten million dollars. The annual cost savings for U.S. Air Force engines is approximately $313,000.00 with a capital value of approximately 3.1 million dollars. The program will result in the government obtaining bearings at lower costs at equivalent reliability. The bearing industry can recover lost profits during a period of reduced demand and higher costs.

  15. Titanium carbide coatings for aerospace ball bearings

    Science.gov (United States)

    Boving, Hans J.; Haenni, Werner; Hintermann, HANS-E.

    1988-01-01

    In conventional ball bearings, steel to steel contacts between the balls and the raceways are at the origin of microwelds which lead to material transfer, surface roughening, lubricant breakdown, and finally to a loss in the bearing performances. To minimize the microwelding tendencies of the contacting partners it is necessary to modify their surface materials; the solid to solid collisions themselves are difficult to avoid. The use of titanium carbide coated steel balls can bring spectacular improvements in the performances and lifetimes of both oil-grease lubricated and oil-grease free bearings in a series of severe applications.

  16. Rotor Vibration Reduction via Active Hybrid Bearings

    DEFF Research Database (Denmark)

    Nicoletti, Rodrigo; Santos, Ilmar

    2002-01-01

    The use of fluid power to reduce and control rotor vibration in rotating machines is investigated. An active hybrid bearing is studied, whose main objective is to reduce wear and vibration between rotating and stationary machinery parts. By injecting pressurised oil into the oil film, through...... orifices machined in the bearing pads, one can alter the machine dynamic characteristics, thus enhancing its operational range. A mathematical model of the rotor-bearing system, as well as of the hydraulic system, is presented. Numerical results of the system frequency response show good agreement...

  17. On Controllable Elastohydrodynamic Fluid Film Bearings

    DEFF Research Database (Denmark)

    Haugaard, Martin Asger

    This thesis gives a theoretical description of the active tilting-pad journal bearing (ATPJB). It provides the qualified reader with the tools to model an ATPJB, while staying clear of pitfalls. The model is based on well known techniques and allows for local stability analyses, harmonic stationary...... are performed for a tilting-pad journal bearing (TPJB) and an ATPJB under static conditions, followed by a generalisation to dynamic conditions (transient as well as stationary harmonic). These analyses will be of interest to experimentalists, since they permit experiments performed on scaled down test rigs...... the addition of a control system may just as well harm rotor-bearing performance as improve it....

  18. Conical Magnetic Bearing Development and Magnetic Bearing Testing for Extreme Temperature Environments

    Science.gov (United States)

    Keith, Theo G., Jr.; Jansen, Mark

    2004-01-01

    The main proposed research of this grant were: to design a high-temperature, conical magnetic bearing facility, to test the high-temperature, radial magnetic bearing facility to higher speeds, to investigate different backup bearing designs and materials, to retrofit the high-temperature test facility with a magnetic thrust bearing, to evaluate test bearings at various conditions, and test several lubricants using a spiral orbit tribometer. A high-temperature, conical magnetic bearing facility has been fully developed using Solidworks. The facility can reuse many of the parts of the current high-temperature, radial magnetic bearing, helping to reduce overall build costs. The facility has the ability to measure bearing force capacity in the X, Y, and Z directions through a novel bearing mounting design. The high temperature coils and laminations, a main component of the facility, are based upon the current radial design and can be fabricated at Texas A&M University. The coil design was highly successful in the radial magnetic bearing. Vendors were contacted about fabrication of the high temperature lamination stack. Stress analysis was done on the laminations. Some of the components were procured, but due to budget cuts, the facility build up was stopped.

  19. Asymmetric synthesis of cyclopentanes bearing four contiguous stereocenters via an NHC-catalyzed Michael/Michael/esterification domino reaction† †Electronic supplementary information (ESI) available: Experimental procedures and characterization date (NMR, IR, MS, HPLC). CCDC 1437686. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c5cc09581f Click here for additional data file. Click here for additional data file.

    Science.gov (United States)

    Shu, Tao; Ni, Qijian; Song, Xiaoxiao; Zhao, Kun; Wu, Tianyu; Puttreddy, Rakesh; Rissanen, Kari

    2016-01-01

    An NHC-catalyzed Michael/Michael/esterification domino reaction via homoenolate/enolate intermediates for the asymmetric synthesis of tetrasubstituted cyclopentanes bearing four contiguous stereocenters is described. A variety of α,β-unsaturated aldehydes and 2-nitroallylic acetates react well with good domino yields and high stereoselectivities. PMID:26750327

  20. Vibration Characteristics of Hydrodynamic Fluid Film Pocket Journal Bearings

    Directory of Open Access Journals (Sweden)

    N. S. Feng

    2010-01-01

    Full Text Available Theoretical analyses of hydrodynamic fluid film bearings with different bearing profiles rely on solutions of the Reynolds equation. This paper presents an approach used for analysing the so-called pocket bearings formed from a combination of offset circular bearing profiles. The results show that the variation of the dynamic bearing characteristics with different load inclinations for the pocket bearings is less than that for the elliptic bearing counterpart. It is shown that the natural frequencies as well as the critical speeds, and hence the vibrational behaviour, can also be significantly different for an industrial rotor supported by the different bearings.

  1. International Space Station Alpha's bearing, motor, and roll ring module developmental testing and results

    Science.gov (United States)

    Obrien, David L.

    1994-01-01

    This paper presents the design and developmental testing associated with the bearing, motor, and roll ring module (BMRRM) used for the beta rotation axis on International Space Station Alpha (ISSA). The BMRRM with its controllers located in the electronic control unit (ECU), provides for the solar array pointing and tracking functions as well as power and signal transfer across a rotating interface.

  2. Magnetic bearings: A key technology for advanced rocket engines?

    Science.gov (United States)

    Girault, J. PH.

    1992-01-01

    For several years, active magnetic bearings (AMB) have demonstrated their capabilities in many fields, from industrial compressors to control wheel suspension for spacecraft. Despite this broad area, no significant advance has been observed in rocket propulsion turbomachinery, where size, efficiency, and cost are crucial design criteria. To this respect, Societe Europeenne de Propulsion (SEP) had funded for several years significant efforts to delineate the advantages and drawbacks of AMB applied to rocket propulsion systems. Objectives of this work, relative technological basis, and improvements are described and illustrated by advanced turbopump layouts. Profiting from the advantages of compact design in cryogenic environments, the designs show considerable improvements in engine life, performances, and reliability. However, these conclusions should still be tempered by high recurrent costs, mainly due to the space-rated electronics. Development work focused on this point and evolution of electronics show the possibility to decrease production costs by an order of magnitude.

  3. A Ruthenium(III)-Oxyl Complex Bearing Strong Radical Character.

    Science.gov (United States)

    Shimoyama, Yoshihiro; Ishizuka, Tomoya; Kotani, Hiroaki; Shiota, Yoshihito; Yoshizawa, Kazunari; Mieda, Kaoru; Ogura, Takashi; Okajima, Toshihiro; Nozawa, Shunsuke; Kojima, Takahiko

    2016-11-02

    Proton-coupled electron-transfer oxidation of a Ru(II) -OH2 complex, having an N-heterocyclic carbene ligand, gives a Ru(III) -O(.) species, which has an electronically equivalent structure of the Ru(IV) =O species, in an acidic aqueous solution. The Ru(III) -O(.) complex was characterized by spectroscopic methods and DFT calculations. The oxidation state of the Ru center was shown to be close to +3; the Ru-O bond showed a lower-energy Raman scattering at 732 cm(-1) and the Ru-O bond length was estimated to be 1.77(1) Å. The Ru(III) -O(.) complex exhibits high reactivity in substrate oxidation under catalytic conditions; particularly, benzaldehyde and the derivatives are oxidized to the corresponding benzoic acid through C-H abstraction from the formyl group by the Ru(III) -O(.) complex bearing a strong radical character as the active species.

  4. Development of alternatives to lead-bearing solders

    Energy Technology Data Exchange (ETDEWEB)

    Vianco, P.T. [Sandia National Labs., Albuquerque, NM (United States)

    1993-07-01

    Soldering technology, using tin-lead alloys has had a significant role in the packaging of highly functional, low cost electronic devices. The elimination of lead from all manufactured products, whether through legislation or tax incentives, will impact the electronics community which uses lead-containing solders. In response to these proposed measures, the National Center for Manufacturing Sciences has established a multi-year program involving participants from industry, academia, and the national laboratories with the objective to identify potential replacements for lead-bearing solders. Selection of candidate alloys is based upon the analysis of materials properties, manufacturability, modeling codes for reliability prediction, as well as toxicological properties and resource availability, data developed in the program.

  5. Oxidation of ultra low carbon and silicon bearing steels

    Energy Technology Data Exchange (ETDEWEB)

    Suarez, Lucia [CTM - Technologic Centre, Materials Technology Area, Manresa, Barcelona (Spain)], E-mail: lucia.suarez@ctm.com.es; Rodriguez-Calvillo, Pablo [CTM - Technologic Centre, Materials Technology Area, Manresa, Barcelona (Spain)], E-mail: pablo.rodriguez@ctm.com.es; Houbaert, Yvan [Department of Materials Science and Engineering, University of Ghent (Belgium)], E-mail: Yvan.Houbaert@UGent.be; Colas, Rafael [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon (Mexico)], E-mail: rcolas@mail.uanl.mx

    2010-06-15

    Oxidation tests were carried out in samples from an ultra low carbon and two silicon bearing steels to determine the distribution and morphology of the oxide species present. The ultra low carbon steel was oxidized for short periods of time within a chamber designed to obtain thin oxide layers by controlling the atmosphere, and for longer times in an electric furnace; the silicon steels were reheated only in the electric furnace. The chamber was constructed to study the behaviour encountered during the short period of time between descaling and rolling in modern continuous mills. It was found that the oxide layers formed on the samples reheated in the electric furnace were made of different oxide species. The specimens treated in the chamber had layers made almost exclusively of wustite. Selected oxide samples were studied by scanning electron microscopy to obtain electron backscattered diffraction patterns, which were used to identify the oxide species in the layer.

  6. The polar bear and its protection

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — No census has been made of the polar bear population and indeed the general movements of the animals within their range are poorly known. At present it is not...

  7. Bear Lake-Minidoka - Phragmites Control

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Bear Lake: Phragmites patches were sprayed on the refuge & north of the lake proper. Minidoka: patches along the Snake River & Lake Walcott were treated with...

  8. Mercury biomagnification in polar bears ( Ursus maritimus)

    Science.gov (United States)

    Horton, T. W.; Blum, J. D.; Xie, Z.; Hren, M.; Chamberlain, C. P.

    2007-12-01

    Mercury biomagnification occurs in a variety of ecosystems resulting in greater potential for toxicological effects in higher-level trophic feeders. However, Hg transport pathways through different foodweb channels are not well known, particularly in high-latitude systems affected by atmospheric Hg deposition associated with snow and ice. Stable carbon and nitrogen isotope ratios and Hg concentrations determined for 26 late 19th and early 20th century polar bear hair specimens collected from cataloged museum collections elucidate relationships between high latitude marine foodweb structure and Hg transport pathways. Nitrogen and carbon isotopic compositions suggest that polar bears derive nutrition from both open water (pelagic) and ice associated (sympagic) foodweb channels. Correlation between Hg concentrations and nitrogen isotope compositions indicate mercury biomagnification occurred in most of the polar bears investigated. Interpretation of stable isotope based foodweb structure in concert with Hg concentrations further suggests that Hg biomagnification occurred to a greater degree in polar bears participating in pelagic foodweb channels.

  9. AX-5 space suit bearing torque investigation

    Science.gov (United States)

    Loewenthal, Stuart; Vykukal, Vic; Mackendrick, Robert; Culbertson, Philip, Jr.

    1990-01-01

    The symptoms and eventual resolution of a torque increase problem occurring with ball bearings in the joints of the AX-5 space suit are described. Starting torques that rose 5 to 10 times initial levels were observed in crew evaluation tests of the suit in a zero-g water tank. This bearing problem was identified as a blocking torque anomaly, observed previously in oscillatory gimbal bearings. A large matrix of lubricants, ball separator designs and materials were evaluated. None of these combinations showed sufficient tolerance to lubricant washout when repeatedly cycled in water. The problem was resolved by retrofitting a pressure compensated, water exclusion seal to the outboard side of the bearing cavity. The symptoms and possible remedies to blocking are discussed.

  10. Polar bear research in Alaska, spring 1982

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — An investigation of the ecology and population dynamics of Alaskan polar bears has continued since 1967. As part of that program, U.S. Fish and Wildlife Service...

  11. Polar bear research in Alaska, spring 1981

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — An investigation of the ecology and population dynamics of Alaskan polar bears has continued since 1967. As part of that program, U.S. Fish and Wildlife Service...

  12. Telemetry techniques used on Kodiak brown bear

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report summarizes the results of a study on the techniques used to monitor the movements of Kodiak brown bears instrumented with radio transmitters. Methods...

  13. LIGHT-WEIGHT LOAD-BEARING STRUCTURE

    DEFF Research Database (Denmark)

    2009-01-01

    The invention relates to a light-weight load-bearing structure (1) with optimized compression zone (2), where along one or more compression zones (2) in the structure (1) to be cast a core (3) of strong concrete is provided, which core (3) is surrounded by concrete of less strength (4) compared...... to the core (3) of strong concrete. The invention also relates to a method of casting of light-weight load-bearing structures (1) with optimized compression zone (2) where one or more channels, grooves, ducts, pipes and/or hoses (5) formed in the load-bearing structure (1) serves as moulds for moulding one...... or more cores (3) of strong concrete in the light-weight load-bearing structure (1)....

  14. Active Magnetic Bearings – Magnetic Forces

    DEFF Research Database (Denmark)

    Kjølhede, Klaus

    2006-01-01

    Parameter identification procedures and model validation are major steps towards intelligent machines supported by active magnetic bearings (AMB). The ability of measuring the electromagnetic bearing forces, or deriving them from measuring the magnetic flux, strongly contributes to the model...... validation and leads to novel approaches in identifying crucial rotor parameters. This is the main focus of this paper, where an intelligent AMB is being developed with the aim of aiding the accurate identification of damping and stiffness coefficients of journal bearings and seals. The main contribution...... of the magnetic forces are led by using different experimental tests: (I) by using hall sensors mounted directly on the poles (precise measurements of the magnetic flux) and by an auxiliary system, composed of strain gages and flexible beams attached to the rotor; (II) by measuring the input current and bearing...

  15. Novel nano bearings constructed by physical adsorption

    Science.gov (United States)

    Zhang, Yongbin

    2015-09-01

    The paper proposes a novel nano bearing formed by the physical adsorption of the confined fluid to the solid wall. The bearing is formed between two parallel smooth solid plane walls sliding against one another, where conventional hydrodynamic lubrication theory predicted no lubricating effect. In this bearing, the stationary solid wall is divided into two subzones which respectively have different interaction strengths with the lubricating fluid. It leads to different physical adsorption and slip properties of the lubricating fluid at the stationary solid wall respectively in these two subzones. It was found that a significant load-carrying capacity of the bearing can be generated for low lubricating film thicknesses, because of the strong physical adsorption and non-continuum effects of the lubricating film.

  16. Cavitation Peening of Aerospace Bearings Project

    Data.gov (United States)

    National Aeronautics and Space Administration — High-value bearings are a critical part of the safety, reliability, cost and performance of modern aircraft. A typical passenger jet will have 100 to 175 high-valve...

  17. RUBBER BEARINGS FOR DOWN-HOLE PUMPS

    Energy Technology Data Exchange (ETDEWEB)

    Bob Sullivan Mammoth Pacific, L.P.

    2005-09-07

    Synopsis of project activity: 1998--Awarded cost share grant from DOE. 1st Qtr 1999--Developed fail safe lubricating system. 2nd Qtr 1999--Performed first large scale test with nitrile based bearings. It failed due to material swelling. Failure was blamed on improper tolerance. 3rd Qtr 1999--Material tests were performed with autoclaves and exposure tests to Casa Diablo fluids. Testing of Viton materials began. Alternate bearing designs were developed to limit risk of improper tolerances. 4th Qtr 1999--Site testing indicated a chemical attack on the bearing material caused the test failure and not improper bearing tolerance. 1st Qtr 2000--The assistance of Brookhaven National Laboratory was obtained in evaluating the chemical attack. The National Laboratory also began more elaborate laboratory testing on bearing materials. 2nd Qtr 2000--Testing indicated Viton was an inappropriate material due to degradation in Casa Diablo fluid. Testing of EPDM began. 3rd Qtr 2001--EPDM bearings were installed for another large scale test. Bearings failed again due to swelling. Further testing indicated that larger then expected oil concentrations existed in lubricating water geothermal fluid causing bearing failure. 2002-2003--Searched for and tested several materials that would survive in hot salt and oil solutions. Kalrez{reg_sign}, Viton{reg_sign}ETP 500 and Viton{reg_sign}GF were identified as possible candidates. 2003-2005--Kalrez{reg_sign}has shown superior resistance to downhole conditions at Casa Diablo from among the various materials tested. Viton ETP-500 indicated a life expectancy of 13 years and because it is significantly less expensive then Kalrez{reg_sign}, it was selected as the bearing material for future testing. Unfortunately during the laboratory testing period Dupont Chemical chose to stop manufacturing this specific formulation and replaced it with Viton ETP 600S. The material is available with six different fillers; three based on zinc oxide and three

  18. Active magnetic bearings for optimum turbomachinery design

    Science.gov (United States)

    Hustak, J.; Kirk, R. G.; Schoeneck, K. A.

    1985-01-01

    The design and shop test results are given for a high speed eight stage centrifugal compressor supported by active magnetic bearings. A brief summary of the rotor dynamics analysis is presented with specific attention given to design considerations for optimum rotor stability. The concerns for retrofit of magnetic bearings in existing machinery are discussed with supporting analysis of a four stage centrifugal compressor. Recommendations are given on design and analysis requirements for successful machinery operation of either retrofit or new design turbomachinery.

  19. Silicon Nitride Balls For Cryogenic Bearings

    Science.gov (United States)

    Butner, Myles F.; Ng, Lillian W.

    1990-01-01

    Resistance to wear greater than that of 440C steel. Experiments show lives of ball bearings immersed in liquid nitrogen or liquid oxygen increased significantly when 440C steel balls (running on 440C steel races) replaced by balls of silicon nitride. Developed for use at high temperatures, where lubrication poor or nonexistent. Best wear life of any bearing tested to date and ball material spalls without fracturing. Plans for future tests call for use of liquid oxygen as working fluid.

  20. Flywheel energy storage with superconductor magnetic bearings

    Energy Technology Data Exchange (ETDEWEB)

    Weinberger, Bernard R. (Avon, CT); Lynds, Jr., Lahmer (Glastonbury, CT); Hull, John R. (Hinsdale, IL)

    1993-01-01

    A flywheel having superconductor bearings has a lower drag to lift ratio that translates to an improvement of a factor of ten in the rotational decay rate. The lower drag results from the lower dissipation of melt-processed YBCO, improved uniformity of the permanent magnet portion of the bearings, operation in a different range of vacuum pressure from that taught by the art, and greater separation distance from the rotating members of conductive materials.

  1. Passive magnetic bearings for vehicular electromechanical batteries

    Energy Technology Data Exchange (ETDEWEB)

    Post, R

    1996-03-01

    This report describes the design of a passive magnetic bearing system to be used in electromechanical batteries (flywheel energy storage modules) suitable for vehicular use. One or two such EMB modules might, for example, be employed in a hybrid-electric automobile, providing efficient means for power peaking, i.e., for handling acceleration and regenerative braking power demands at high power levels. The bearing design described herein will be based on a ''dual-mode'' operating regime.

  2. Contact fatigue in rolling-element bearings

    CSIR Research Space (South Africa)

    Fernandes, PJL

    1997-06-01

    Full Text Available to that encountered along the pitch-line of gear teeth \\[1\\]. In the early stages of damage, pure rolling forms a highly polished surface, as shown in the case of a bearing cup from a large thrust (a) (b) Fig. 1. Schematic... the inner ring of a thrust bearing \\[5\\]. Extensive surface damage, probably resulting from the action of solid particles entrapped in the lubricating fluid, is clearly noticeable, as is the through- crack emanating from...

  3. Active magnetic bearings used as exciters for rolling element bearing outer race defect diagnosis.

    Science.gov (United States)

    Xu, Yuanping; Di, Long; Zhou, Jin; Jin, Chaowu; Guo, Qintao

    2016-03-01

    The active health monitoring of rotordynamic systems in the presence of bearing outer race defect is considered in this paper. The shaft is assumed to be supported by conventional mechanical bearings and an active magnetic bearing (AMB) is used in the mid of the shaft location as an exciter to apply electromagnetic force to the system. We investigate a nonlinear bearing-pedestal system model with the outer race defect under the electromagnetic force. The nonlinear differential equations are integrated using the fourth-order Runge-Kutta algorithm. The simulation and experimental results show that the characteristic signal of outer race incipient defect is significantly amplified under the electromagnetic force through the AMBs, which is helpful to improve the diagnosis accuracy of rolling element bearing׳s incipient outer race defect. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

  4. Effects of fluid inertia and bearing flexibility on the performance of finite length journal bearing

    Science.gov (United States)

    Javorova, Juliana; Alexandrov, Vassil

    2017-02-01

    The paper describes the theoretical study concerning the effect of lubricant inertia forces and deformability of the bearing elastic layer on the performance of a plane journal bearing. The problem is investigated for a Newtonian lubricant under isothermal and isoviscous conditions. The analysis considers the generalized Reynolds equation governing the flow of lubricant in the clearance space and the linear elasticity equation governing the displacement field in the bearing shell. An iterative numerical procedure with successive over relaxation is used to pressure distribution within the lubricated conjunction. Bearing performance characteristics have been presented for typically selected values of generalized Reynolds number Re* and elasticity parameters of the elastic liner. It has been observed that the combined effect of fluid inertia forces and bearing flexibility affects the performance characteristics of dynamically loaded journal bearing.

  5. Rotordynamics and bearing design of turbochargers

    Science.gov (United States)

    Chen, Wen Jeng

    2012-05-01

    Turbochargers have gained significant attention in recent years. They are already widely used in automotive, locomotive, and marine applications with diesel engines. They are also applied in the aerospace application to increase the engine performance now. The turbochargers used in automotive and aerospace industry are very light-weight with operating speeds above 100,000 rpm. The turbochargers used in locomotive and marine applications are relatively heavy in size and power compared to the automotive and aerospace applications, and the maximum continuous operating speeds are around 30,000 rpm depending on the diesel engine power rating. Floating ring bushings, semi-floating dampers, ball bearings, and ball bearings with dampers are commonly used in automotive applications for small turbochargers. However, these bearings may not be appropriate for large turbochargers in locomotive and marine applications. Instead, multi-lobed bearings with and without squeeze film dampers are commonly used in these heavy-duty turbochargers. This paper deals with the rotordynamic characteristics of larger turbochargers in locomotive and marine applications. Various bearing designs are discussed. Bearing design parameters are studied and optimal values are suggested. Test results are also presented to support the analytical simulation.

  6. Bearing and gear steels for aerospace applications

    Science.gov (United States)

    Zaretsky, Erwin V.

    1990-01-01

    Research in metallurgy and processing for bearing and gear steels has resulted in improvements in rolling-element bearing and gear life for aerospace application by a factor of approximately 200 over that obtained in the early 1940's. The selection and specification of a bearing or gear steel is dependent on the integration of multiple metallurgical and physical variables. For most aerospace bearings, through-hardened VIM-VAR AISI M-50 steel is the material of preference. For gears, the preferential material is case-carburized VAR AISI 9310. However, the VAR processing for this material is being replaced by VIM-VAR processing. Since case-carburized VIM-VAR M-50NiL incorporates the desirable qualities of both the AISI M-50 and AISI 9310 materials, optimal life and reliability can be achieved in both bearings and gears with a single steel. Hence, this material offers the promise of a common steel for both bearings and gears for future aerospace applications.

  7. Performance of a continuous flow ventricular assist device: magnetic bearing design, construction, and testing.

    Science.gov (United States)

    Allaire, P; Hilton, E; Baloh, M; Maslen, E; Bearnson, G; Noh, D; Khanwilkar, P; Olsen, D

    1998-06-01

    A new centrifugal continuous flow ventricular assist device, the CFVAD III, which is fully magnetic bearing suspended, has been developed. It has only one moving part (the impeller), has no contact (magnetic suspension), is compact, and has minimal heating. A centrifugal impeller of 2 inch outer diameter is driven by a permanent magnet brushless DC motor. This paper discusses the design, construction, testing, and performance of the magnetic bearings in the unit. The magnetic suspension consists of an inlet side magnetic bearing and an outlet side magnetic bearing, each divided into 8 pole segments to control axial and radial displacements as well as angular displacements. The magnetic actuators are composed of several different materials to minimize size and weight while having sufficient load capacity to support the forces on the impeller. Flux levels in the range of 0.1 T are employed in the magnetic bearings. Self sensing electronic circuits (without physical sensors) are employed to determine the impellar position and provide the feedback control signal needed for the magnetic bearing control loops. The sensors provide position sensitivity of approximately 0.025 mm. A decentralized 5 axis controller has been developed using modal control techniques. Proportional integral derivative controls are used for each axis to levitate the magnetically supported impeller.

  8. A Wide Bandwidth Model for the Electrical Impedance of Magnetic BearingS

    Science.gov (United States)

    Meeker, David C.; Maslen, Eric H.; Noh, Myounggyu D.

    1996-01-01

    Magnetic bearings are often designed using magnetic circuit theory. When these bearings are built, however, effects not included in the usual circuit theory formulation have a significant influence on bearing performance. Two significant sources of error in the circuit theory approach are the neglect of leakage and fringing effects and the neglect of eddy current effects. This work formulates an augmented circuit model in which eddy current and flux leakage and fringing effects are included. Through the use of this model, eddy current power losses and actuator bandwidth can be derived. Electrical impedance predictions from the model are found to be in good agreement with experimental data from a typical magnetic bearing.

  9. Fault Tolerant Magnetic Bearing Testing and Conical Magnetic Bearing Development for Extreme Temperature Environments

    Science.gov (United States)

    Keith, Theo G., Jr.; Clark, Daniel

    2004-01-01

    During the six month tenure of the grant, activities included continued research of hydrostatic bearings as a viable backup-bearing solution for a magnetically levitated shaft system in extreme temperature environments (1000 F), developmental upgrades of the fault-tolerant magnetic bearing rig at the NASA Glenn Research Center, and assisting in the development of a conical magnetic bearing for extreme temperature environments, particularly turbomachinery. It leveraged work from the ongoing Smart Efficient Components (SEC) and the Turbine-Based Combined Cycle (TBCC) program at NASA Glenn Research Center. The effort was useful in providing technology for more efficient and powerful gas turbine engines.

  10. Magnetic bearings for a high-performance optical disk buffer, volume 1

    Science.gov (United States)

    Hockney, Richard; Adler, Karen; Anastas, George, Jr.; Downer, James; Flynn, Frederick; Goldie, James; Gondhalekar, Vijay; Hawkey, Timothy; Johnson, Bruce

    1990-01-01

    The innovation investigated in this project was the application of magnetic bearing technology to the translator head of an optical-disk data storage device. Both the capability for space-based applications and improved performance are expected to result. The phase 1 effort produced: (1) detailed specifications for both the translator-head and rotary-spindel bearings; (2) candidate hardware configurations for both bearings with detail definition for the translator head; (3) required characteristics for the magnetic bearing control loops; (4) position sensor selection; and (5) definition of the required electronic functions. The principal objective of Phase 2 was the design, fabrication, assembly, and test of the magnetic bearing system for the translator head. The scope of work included: (1) mechanical design of each of the required components; (2) electrical design of the required circuitry; (3) fabrication of the component parts and bread-board electronics; (4) generation of a test plan; and (5) integration of the prototype unit and performance testing. The project has confirmed the applicability of magnetic bearing technology to suspension of the translator head of the optical disk device, and demonstrated the achievement of all performance objectives. The magnetic bearing control loops perform well, achieving 100 Hz nominal bandwidth with phase margins between 37 and 63 degrees. The worst-case position resolution is 0.02 micron in the displacement loops and 1 micron rad in the rotation loops, The system is very robust to shock disturbances, recovering smoothly even when collisions occur between the translator and frame. The unique start-up/shut-down circuit has proven very effective.

  11. Transient Vibration Prediction for Rotors on Ball Bearings Using Load-dependent Non-linear Bearing Stiffness

    Science.gov (United States)

    Fleming, David P.; Poplawski, J. V.

    2002-01-01

    Rolling-element bearing forces vary nonlinearly with bearing deflection. Thus an accurate rotordynamic transient analysis requires bearing forces to be determined at each step of the transient solution. Analyses have been carried out to show the effect of accurate bearing transient forces (accounting for non-linear speed and load dependent bearing stiffness) as compared to conventional use of average rolling-element bearing stiffness. Bearing forces were calculated by COBRA-AHS (Computer Optimized Ball and Roller Bearing Analysis - Advanced High Speed) and supplied to the rotordynamics code ARDS (Analysis of Rotor Dynamic Systems) for accurate simulation of rotor transient behavior. COBRA-AHS is a fast-running 5 degree-of-freedom computer code able to calculate high speed rolling-element bearing load-displacement data for radial and angular contact ball bearings and also for cylindrical and tapered roller beatings. Results show that use of nonlinear bearing characteristics is essential for accurate prediction of rotordynamic behavior.

  12. Polar bears: the fate of an icon.

    Science.gov (United States)

    Fitzgerald, Kevin T

    2013-11-01

    Polar bears are one of the most iconic animals on our planet. Worldwide, even people who would never see one are drawn to these charismatic arctic ice hunters. They are the world's largest terrestrial carnivore, and despite being born on land, they spend most of their lives out on the sea ice and are considered a marine mammal. Current global studies estimate there are around 20,000 animals in some 19 discrete circumpolar populations. Aside from pregnant females denning in the winter months to give birth, the white bears do not hibernate. They spend their winters on the sea ice hunting seals, an activity they are spectacularly adapted for. Research on these animals is incredibly difficult because of the inhospitable surroundings they inhabit and how inaccessible they make the bears. For many years, the sum of our understanding of the natural history of polar bears came from tracks, scats, the remains of their kills, abandoned dens, and anecdotal observations of native hunters, explorers, and early biologists. Nonetheless, the last 40 years have seen a much better picture of their biology emerge thanks to, first, dedicated Canadian researchers and, later, truly international efforts of workers from many countries. Veterinarians have contributed to our knowledge of the bears by delivering and monitoring anesthesia, obtaining blood samples, performing necropsies, investigating their reproduction, conducting radiotelemetry studies, and examining their behavior. Recently, new technologies have been developed that revolutionize the study of the lives and natural history of undisturbed polar bears. These advances include better satellite radiotelemetry equipment and the development of remote-controlled miniature devices equipped with high-definition cameras. Such new modalities provide dramatic new insights into the life of polar bears. The remarkable degree of specialized adaptation to life on the sea ice that allowed the bears to be successful is the very reason that

  13. Critical Pressures of the Thrust Bearing Using a Magnetic Fluid

    OpenAIRE

    長屋, 幸助; 武田, 定彦; 佐藤, 淳; 井開, 重男; 関口, 肇; 斉藤, 登

    1990-01-01

    This paper proposes a thrust bearing lubricated by a magnetic fluid under a magnetic field. The critical pressures of the bearing versus the magnitude of the magnetic flux densities have been investigated experimentally. It is clarified that the critical pressures of the proposed bearing are larger than those of the normal lubricant bearing under high speeds.

  14. Wear numbers for ball cup and journal bearings

    NARCIS (Netherlands)

    Ligterink, D.J.; Moes, H.

    1980-01-01

    A wear number is defined for ball cup bearings and for journal bearings where the cup and the cylindrical bearing are made of soft material. This dimensionless wear number provides a relation between the following five quantities: the radius of the ball or the length of the journal bearing in millim

  15. 49 CFR 230.102 - Tender plain bearing journal boxes.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Tender plain bearing journal boxes. 230.102... Locomotives and Tenders Running Gear § 230.102 Tender plain bearing journal boxes. Plain bearing journal boxes... expected to damage the bearing; or have a detrimental effect on the lubrication of the journal and...

  16. Identifying lubricant options for compressor bearing designs

    Science.gov (United States)

    Karnaz, J.; Seeton, C.; Dixon, L.

    2017-08-01

    Today’s refrigeration and air conditioning market is not only driven by the environmental aspects of the refrigerants, but also by the energy efficiency and reliability of system operation. Numerous types of compressor designs are used in refrigeration and air conditioning applications which means that different bearings are used; and in some cases, multiple bearing types within a single compressor. Since only one lubricant is used, it is important to try to optimize the lubricant to meet the various demands and requirements for operation. This optimization entails investigating different types of lubricant chemistries, viscosities, and various formulation options. What makes evaluating these options more challenging is the refrigerant which changes the properties of the lubricant delivered to the bearing. Once the lubricant and refrigerant interaction are understood, through various test methods, then work can start on collaborating with compressor engineers on identifying the lubricant chemistry and formulation options. These interaction properties are important to the design engineer to make decisions on the adequacy of the lubricant before compressor tests are started. This paper will discuss the process to evaluate lubricants for various types of compressors and bearing design with focus on what’s needed for current refrigerant trends. In addition, the paper will show how the lubricant chemistry choice can be manipulated through understanding of the bearing design and knowledge of interaction with the refrigerant to maximize performance. Emphasis will be placed on evaluation of synthetic lubricants for both natural and synthetic low GWP refrigerants.

  17. Nonlinear vibrations and stability of aerostatic bearing

    Directory of Open Access Journals (Sweden)

    Kozánek J.

    2008-12-01

    Full Text Available Bearings based on aerostatic principle belong to the new machine elements advantageous for low- and high-speed applications, but their dynamic and stability properties are not yet sufficiently known. This paper presents a new elaborated method and gained results of theoretical investigation of dynamic properties of aerostatic bearing in general dimensionless form. It is aimed also as a supporting tool for diagnostic and identification methods used at developing of new bearings proposed by TECHLAB, Prague for industrial applications. Mathematical model expresses nonlinear and evolutive properties in the entire area of bearing clearance, contains sufficient number of free parameters in functions of restoring and damping forces and can therefore describe all types of motions occurring in gas bearings as periodic, quasi-periodic, including beats and instability, which can leads to chaotic and self-excited vibrations. The influence of non-diagonal elements of stiffness and damping matrices of linearized model on the spectral properties and the stability of system is investigated, too.

  18. Bearing tester data compilation, analysis and reporting and bearing math modeling, volume 1

    Science.gov (United States)

    Marshall, D. D.; Montgomery, E. E.; New, L. S.; Stone, M. A.; Tiller, B. K.

    1984-01-01

    Thermal and mechanical models of high speed angular contact ball bearings operating in LOX and LN2 were developed and verified with limited test data in an effort to further understand the parameters that determine or effect the SSME turbopump bearing operational characteristics and service life. The SHABERTH bearing analysis program which was adapted to evaluate shaft bearing systems in cryogenics is not capable of accommodating varying thermal properties and two phase flow. A bearing model with this capability was developed using the SINDA thermal analyzer. Iteration between the SHABERTH and the SINDA models enable the establishment of preliminary bounds for stable operation in LN2. These limits were established in terms of fluid flow, fluid inlet temperature, and axial load for a shaft speed of 30,000 RPM.

  19. Oxford phase III meniscal bearing fracture: case report.

    Science.gov (United States)

    Lim, Hong-Chul; Shon, Won-Yong; Kim, Seung-Ju; Bae, Ji-Hoon

    2014-01-01

    Meniscal bearing fracture is a rare complication of phase III Oxford unicompartmental knee replacement (UKR). We report a case of a meniscal bearing fracture that occurred 7 years after phase III Oxford medial UKR. The meniscal bearing showed uneven delamination of the polyethylene in the thinnest articular surface and an impingement lesion. This lesion initiated a fatigue crack that propagated to cause failure of the meniscal bearing. This is the first report of a meniscal bearing fracture without a posterior marker wire.

  20. Wear numbers for ball cup and journal bearings

    OpenAIRE

    Ligterink, D.J.; Moes, H.

    1980-01-01

    A wear number is defined for ball cup bearings and for journal bearings where the cup and the cylindrical bearing are made of soft material. This dimensionless wear number provides a relation between the following five quantities: the radius of the ball or the length of the journal bearing in millimetres, the wear modulus in newtons per square millimetre, the maximum wear depth rate of the cup or the cylindrical bearing in millimetres per second, the force between the mating surfaces in newto...

  1. Higher forgotten joint score for fixed-bearing than for mobile-bearing total knee arthroplasty.

    Science.gov (United States)

    Thienpont, E; Zorman, D

    2016-08-01

    To compare the postoperative subjective outcome for fixed- and mobile-bearing total knee arthroplasty (TKA) by using the forgotten joint score (FJS-12), a new patient-reported outcome score of 12 questions evaluating the potential of a patient to forget about his operated joint. The hypothesis of this study was that a mobile-bearing TKA would have a higher level of forgotten joint than a fixed-bearing model of the same design. A retrospective cohort study was conducted in 100 patients who underwent TKA at least 1 year [mean (SD) 18 (5) months] before with either a fixed-bearing (N = 50) or a mobile-bearing (N = 50) TKA from the same implant family. Clinical outcome was evaluated with the knee society score and patient-reported outcome with the forgotten joint score. No difference was observed for demographics in between both study groups. The mean (SD) postoperative FJS-12 for the fixed-bearing TKA was 71 (28) compared to a mean (SD) of 56.5 (30) for the mobile-bearing TKA. The clinical relevance of the present retrospective study is that it shows for the first time a significant difference between fixed- and mobile-bearing TKA by using a new patient-reported outcome score. The hypothesis that mobile-bearing TKA would have a higher degree of forgotten joint than a fixed-bearing TKA could not be confirmed. A level I prospective study should be set up to objectivise these findings. IV.

  2. Conceptual Design and Feasibility of Foil Bearings for Rotorcraft Engines: Hot Core Bearings

    Science.gov (United States)

    Howard, Samuel A.

    2007-01-01

    Recent developments in gas foil bearing technology have led to numerous advanced high-speed rotating system concepts, many of which have become either commercial products or experimental test articles. Examples include oil-free microturbines, motors, generators and turbochargers. The driving forces for integrating gas foil bearings into these high-speed systems are the benefits promised by removing the oil lubrication system. Elimination of the oil system leads to reduced emissions, increased reliability, and decreased maintenance costs. Another benefit is reduced power plant weight. For rotorcraft applications, this would be a major advantage, as every pound removed from the propulsion system results in a payload benefit.. Implementing foil gas bearings throughout a rotorcraft gas turbine engine is an important long-term goal that requires overcoming numerous technological hurdles. Adequate thrust bearing load capacity and potentially large gearbox applied radial loads are among them. However, by replacing the turbine end, or hot section, rolling element bearing with a gas foil bearing many of the above benefits can be realized. To this end, engine manufacturers are beginning to explore the possibilities of hot section gas foil bearings in propulsion engines. This overview presents a logical follow-on activity by analyzing a conceptual rotorcraft engine to determine the feasibility of a foil bearing supported core. Using a combination of rotordynamic analyses and a load capacity model, it is shown to be reasonable to consider a gas foil bearing core section. In addition, system level foil bearing testing capabilities at NASA Glenn Research Center are presented along with analysis work being conducted under NRA Cooperative Agreements.

  3. Trace fossils in coal-bearing sequences

    Energy Technology Data Exchange (ETDEWEB)

    Pollard, J.E.

    1988-03-01

    In the past decade trace fossils have been recorded extensively from coal-bearing sediments, differing widely in facies, age and location. Westphalian or Stephanian 'coal-measures' in Britain, Europe and Eastern Canada contain an ichnofauna produced by invertebrates and/or vertebrates in upper delta plain sediments. This contrasts with the marine-related lower delta plain ichnofaunas known from Pennsylvanian rocks of the United States and Permian Gondwana 'coal-measures' of South Africa. Deltaic complexes of Middle Jurassic age in the North Sea basin and Upper Cretaceous age in North America contain marine trace fossils and dinosaur footprints in coastal coal- bearing facies. These case histories illustrate the importance of trace fossils both in facies analysis of coal-bearing sequences and in recording the presence of animals rarely known as body fossils in such clastic sediments. 80 refs., 5 figs.

  4. High Performance Magnetic Bearings for Aero Applications

    Science.gov (United States)

    Allaire, P. E.; Knospe, C. R.; Williams, R. D.; Lewis, D. W.; Barrett, L. E.; Maslen, E. H.; Humphris, R. R.

    1997-01-01

    Several previous annual reports were written and numerous papers published on the topics for this grant. That work is not repeated here in this final report. Only the work completed in the final year of the grant is presented in this final report. This final year effort concentrated on power loss measurements in magnetic bearing rotors. The effect of rotor power losses in magnetic bearings are very important for many applications. In some cases, these losses must be minimized to maximize the length of time the rotating machine can operate on a fixed energy or power supply. Examples include aircraft gas turbine engines, space devices, or energy storage flywheels. In other applications, the heating caused by the magnetic bearing must be removed. Excessive heating can be a significant problem in machines as diverse as large compressors, electric motors, textile spindles, and artificial heart pumps.

  5. STABILITY OF ROTOR-BEARING SYSTEMS

    Directory of Open Access Journals (Sweden)

    Uğur YÜCEL

    2003-03-01

    Full Text Available In various industrial applications there is a need for higher speed, yet reliably operating rotating machinery. A key factor in achieving this type of machinery continues to be the ability to accurately predict the dynamic response and stability of a rotor-bearing system. This paper introduces and explains the nature of rotordynamic phenomena from comparatively simple analytic models. Starting with the most simple rotor model that is supported in two rigid bearings at its ends, the more realistic and more involved cases are considered by incorporating the effects of flexible bearings. Knowledge of these phenomena is fundamental to an understanding of the behavior of complex models, which corresponds to the real rotors of turbomachines.

  6. Hydrolyzable polyureas bearing hindered urea bonds.

    Science.gov (United States)

    Ying, Hanze; Cheng, Jianjun

    2014-12-10

    Hydrolyzable polymers are widely used materials that have found numerous applications in biomedical, agricultural, plastic, and packaging industrials. They usually contain ester and other hydrolyzable bonds, such as anhydride, acetal, ketal, or imine, in their backbone structures. Here, we report the first design of hydrolyzable polyureas bearing dynamic hindered urea bonds (HUBs) that can reversibly dissociate to bulky amines and isocyanates, the latter of which can be further hydrolyzed by water, driving the equilibrium to facilitate the degradation of polyureas. Polyureas bearing 1-tert-butyl-1-ethylurea bonds that show high dynamicity (high bond dissociation rate), in the form of either linear polymers or cross-linked gels, can be completely degraded by water under mild conditions. Given the simplicity and low cost for the production of polyureas by simply mixing multifunctional bulky amines and isocyanates, the versatility of the structures, and the tunability of the degradation profiles of HUB-bearing polyureas, these materials are potentially of very broad applications.

  7. The ultimate bearing capacity of ice beams

    Directory of Open Access Journals (Sweden)

    Li Liang

    2013-02-01

    Full Text Available It is usually proposed that bearing capacity of the ice beam during its interaction with a sloping hydraulic structure is exhausted when tensile stresses in the beam’s cross-section reach some limit. But besides the tensile stress there is a compressive stress during the interaction with a sloping structure. This can change our estimations of the ultimate bearing capacity and load exerted on the structure. The purpose of the study was to estimate influence of the longitudinal compressive stress on the ice beam’s ultimate bearing capacity. The solution was obtained with the program complex LS-DYNA. Results of the mathematical modeling were compared with data of physical experiments conducted by Sodhi. Good correlation of the results gave possibility to conduct wide numerical experiments and to suggest corrections to the existing methodology.

  8. Powder metallurgy bearings for advanced rocket engines

    Science.gov (United States)

    Fleck, J. N.; Killman, B. J.; Munson, H.E.

    1985-01-01

    Traditional ingot metallurgy was pushed to the limit for many demanding applications including antifriction bearings. New systems require corrosion resistance, better fatigue resistance, and higher toughness. With conventional processing, increasing the alloying level to achieve corrosion resistance results in a decrease in other properties such as toughness. Advanced powder metallurgy affords a viable solution to this problem. During powder manufacture, the individual particle solidifies very rapidly; as a consequence, the primary carbides are very small and uniformly distributed. When properly consolidated, this uniform structure is preserved while generating a fully dense product. Element tests including rolling contact fatigue, hot hardness, wear, fracture toughness, and corrosion resistance are underway on eleven candidate P/M bearing alloys and results are compared with those for wrought 440C steel, the current SSME bearing material. Several materials which offer the promise of a significant improvement in performance were identified.

  9. Robust Bearing Estimation for 3-Component Stations

    Energy Technology Data Exchange (ETDEWEB)

    Claassen, John P.

    1999-06-03

    A robust bearing estimation process for 3-component stations has been developed and explored. The method, called SEEC for Search, Estimate, Evaluate and Correct, intelligently exploits the in- herent information in the arrival at every step of the process to achieve near-optimal results. In particular, the approach uses a consistent framework to define the optimal time-frequency windows on which to make estimates, to make the bearing estimates themselves, to construct metrics helpful in choosing the better estimates or admitting that the bearing is immeasurable, andjinally to apply bias corrections when calibration information is available to yield a single final estimate. The method was applied to a small but challenging set of events in a seismically active region. The method demonstrated remarkable utility by providing better estimates and insights than previously available. Various monitoring implications are noted fiom these findings.

  10. Robust bearing estimation for 3-component stations

    Energy Technology Data Exchange (ETDEWEB)

    CLAASSEN,JOHN P.

    2000-02-01

    A robust bearing estimation process for 3-component stations has been developed and explored. The method, called SEEC for Search, Estimate, Evaluate and Correct, intelligently exploits the inherent information in the arrival at every step of the process to achieve near-optimal results. In particular the approach uses a consistent framework to define the optimal time-frequency windows on which to make estimates, to make the bearing estimates themselves, to construct metrics helpful in choosing the better estimates or admitting that the bearing is immeasurable, and finally to apply bias corrections when calibration information is available to yield a single final estimate. The algorithm was applied to a small but challenging set of events in a seismically active region. It demonstrated remarkable utility by providing better estimates and insights than previously available. Various monitoring implications are noted from these findings.

  11. Bear bile: dilemma of traditional medicinal use and animal protection

    Directory of Open Access Journals (Sweden)

    Nagamatsu Tadashi

    2009-01-01

    Full Text Available Abstract Bear bile has been used in Traditional Chinese Medicine (TCM for thousands of years. Modern investigations showed that it has a wide range of pharmacological actions with little toxicological side effect and the pure compounds have been used for curing hepatic and biliary disorders for decades. However, extensive consumption of bear bile made bears endangered species. In the 1980's, bear farming was established in China to extract bear bile from living bears with "Free-dripping Fistula Technique". Bear farming is extremely inhumane and many bears died of illness such as chronic infections and liver cancer. Efforts are now given by non-governmental organizations, mass media and Chinese government to end bear farming ultimately. At the same time, systematic research has to be done to find an alternative for bear bile. In this review, we focused on the literature, laboratory and clinical results related to bear bile and its substitutes or alternative in English and Chinese databases. We examined the substitutes or alternative of bear bile from three aspects: pure compounds derived from bear bile, biles from other animals and herbs from TCM. We then discussed the strategy for stopping the trading of bear bile and issues of bear bile related to potential alternative candidates, existing problems in alternative research and work to be done in the future.

  12. Grouted Pile and Its Bearing Capacity

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The grouting method applied in bored pile is an improvement to the conventional bored pile. Load tests have proved that grouting under the bored pile tip is an effective method to enhance the bearing capacity of the pile and to reduce the pile settlement. In this paper, the grouting technology is described and pile-load test results are discussed. In order to put the grouting method into design practice, the authors analyze the working mechanism of soil compaction. And, based on the theory of cavities expansion in soil mass, approximate formulae are proposed for estimating the bearing capacity of the grouted pile. The theoretical prediction agrees well with the load test results.

  13. Coated Conductors for the Magnetic Bearing Application

    Science.gov (United States)

    Sass, Felipe; Dias, Daniel Henrique Nogueira; Sotelo, Guilherme Gonçalves; Júnior, Rubens de Andrade

    The second generation (2G) of superconductor wires have been considered for several applications lately. This work presents a preliminary study of superconducting magnetic bearings (SMB) using 2G wires as passive levitators. A superconducting block using stacked 2G wires was built to evaluate the magnetic bearing behavior, thought levitation force measurements, when a permanent magnet cylinder approaches or moves away from the block. The superconducting block was compared with an YBCO bulk with nearly the same dimensions and the results show a promising potential for this application.

  14. Cavitation wear resistance of engine bearing materials

    Science.gov (United States)

    Rac, Aleksandar

    1994-04-01

    The resistance to cavitation erosion of aluminum alloy, and cast and sinte-red lead-bronze, materials which are most frequently used for engine bearings, has been evaluated. The tests were carried out in motor oil at a temperature of 80 C, using a magnetostrictive vibratory tester (20 kHz). The results showed that the cavitation erosion resistance was the greatest in cast lead-bronze. On the contrary, sintered lead-bronze, though of the same chemical composition, had the greatest erosion rate. Additionally, the investigation of the overlay plated bearings showed the overlay was nonresistive to this type of wear.

  15. Carbothermic Reduction of Titanium-Bearing Blast Furnace Slag

    Science.gov (United States)

    Zhen, Yu-Lan; Zhang, Guo-Hua; Chou, Kuo-Chih

    2016-03-01

    The carbothermic reduction experiments were carried out for titanium-bearing blast furnace slag in Panzhihua Iron and Steel Company in argon atmosphere at high temperatures. The effects of reduction temperature, isothermal treatment time and carbon content on the formation of TiC were studied by X-ray diffraction (XRD) and scanning electron microscope (SEM). The XRD pattern results showed that MgAl2O4 phase disappeared and the main phase of the reduced sample was TiC when the reduction temperature was higher than 1,773 K. The SEM pictures showed that the reduction rate of the titanium-bearing blast furnace slag could be increased by enhancing the temperature and the C content (carbon ratio ≤1.0). Furthermore, it was also found that TiC had the tendency of concentrating around the iron. The effects of additives such as Fe and CaCl2 on the formation of TiC were also studied in the present study.

  16. Microstructure and Properties of Laser Additive Manufacturing TC Bearing

    Directory of Open Access Journals (Sweden)

    YANG Jiao-xi

    2016-07-01

    Full Text Available In order to solve the problem of uneven wear of TC bearing that conventional method brought and improve its service life,wear-resistant coating was fabricated on the surface of steel parts matrix with the method of laser additive manufacture. The Cr3C2/Fe based alloy was deposited by laser cladding technique on the inner-sleeve cylindrical and outer-sleeve bore of TC bearing with two different process parameters. The high-performance coating was obtained respectively, of cracks free,no pores and with good metallurgical quality. The morphology of the laser cladding coating was observed by scanning electronic microscope (SEM,the composition was analyzed by EDS,the phase transformation was characterized by XRD. The wear resistance,corrosion resistance and hardness of the laser cladding layer were tested by friction and wear tester,salt spray test chamber and digital micro-hardness tester respectively. The results show that the average micro-hardness of composite coating is HV700. The wear resistance of the composite coating is about 3 times as much as the Ni-based alloy. The corrosion resistance is close to 316L stainless steel.

  17. Dynamic Analysis of a Rotor-Bearing-SFD System with the Bearing Inner Race Defect

    Directory of Open Access Journals (Sweden)

    Junhong Zhang

    2017-01-01

    Full Text Available In this paper, the dynamic behavior of a rotor-bearing-SFD system with the inner race defect of bearing is investigated. The contact force between the rolling element and the race is calculated in Hertzian contact and elastohydrodynamic lubrication condition. The supporting force of the SFD is simulated by integrating the pressure distribution derived from Reynolds’s equation. The equations of motion of the rotor-bearing-SFD system are derived and solved using the fourth-order Runge-Kutta method. The dynamic behavior and the fault characteristics are analyzed with two configurations of the SFD: (1 mounted on the unfaulted bearing and (2 mounted on the faulty bearing. According to the analysis of time-frequency diagram, waterfall plot, and spectral diagram, the results show that the characteristics of inner race defects on bearing frequencies are related to the characteristic multiple frequency of the inner race defect and the fundamental frequency. The speed and defect width have different influence on the distribution and amplitude of frequency. The SFD can enhance the system stability under the bearing fault but the enhancement decreases with the increasing speed. Meanwhile, the beneficial effect of the SFD varies according to the mounted position in the rotor system.

  18. Impact of Fixed-Bearing and Mobile-Bearing Tibial Insert in Unicondylar Knee Arthroplasty

    Directory of Open Access Journals (Sweden)

    Mehmet Faruk Çatma

    2016-06-01

    Full Text Available INTRODUCTION: The aim of the study is to investigate the impact of fixed or mobile-bearing tibial inserts on patellofemoral arthrosis and evaluate which one to be preferred for patients with patellofemoral arthrosis. METHODS: Operated in our clinic between January 2009 and February 2013, 33 with patellofemoral arthritis together with anteromedial compartment arthritis were included in the study. Patellofemoral joints of patients were evaluated according to the scoring system defined by Fulkerson-Shea. RESULTS: Unicondylar knee arthroplasty with fixed-bearing tibial insertsand 22 (66,6% (male: 3, female: 19 and unicondylar knee arthroplasty with mobile-bearing tibial inserts 11 (33,9 % (male: 2, female: 9 were implanted.Average knee flexion was found to be 116,5 (100-135 degrees in 22 patients with mobile-bearing tibial inserts, and 114,5 (95-135 in 11 patients with fixed-bearing tibial inserts. DISCUSSION AND CONCLUSION: Patellofemoral arthrosis is an important factor for unicondylar knee arthroplasty prognosis and one of the determinants of patient satisfaction. Significantly less patellofemoral complaints were seen with UKA with fixed-bearing tibial insert compared to mobile-bearing tibial insert.

  19. Local Attitudes towards Bear Management after Illegal Feeding and Problem Bear Activity

    Directory of Open Access Journals (Sweden)

    David Fraser

    2013-09-01

    Full Text Available The “pot bears” received international media attention in 2010 after police discovered the intentional feeding of over 20 black bears during the investigation of an alleged marijuana-growing operation in Christina Lake, British Columbia, Canada. A two-phase random digit dialing survey of the community was conducted in 2011 to understand local perspectives on bear policy and management, before and after a summer of problem bear activity and government interventions. Of the 159 households surveyed in February 2011, most had neutral or positive attitudes towards bears in general, and supported the initial decision to feed the food-conditioned bears until the autumn hibernation. In contrast to wildlife experts however, most participants supported relocating the problem bears, or allowing them to remain in the area, ahead of killing; in part this arose from notions of fairness despite the acknowledged problems of relocation. Most locals were aware of the years of feeding but did not report it, evidently failing to see it as a serious form of harm, even after many bears had been killed. This underscores the importance of preventive action on wildlife feeding and the need to narrow the gap between public and expert opinion on the likely effects of relocation versus killing.

  20. 75 FR 72784 - Helena National Forest; Montana; Blackfoot Travel Plan EIS

    Science.gov (United States)

    2010-11-26

    ... for grizzly bear security and habitat within the recovery zone. Proposed Action The Helena National... the Continental Divide National Scenic Trail, the Helmville-Gould trail, grizzly bear, elk, and bull... notice was published in the Federal Register on October 29, 2010, FR Doc. 2010- 27353 (75 FR...

  1. Lubricant replacement in rolling element bearings for weapon surety devices

    Energy Technology Data Exchange (ETDEWEB)

    Steinhoff, R.; Dugger, M.T.; Varga, K.S. [Sandia National Laboratories, Albuquerque, NM (United States)

    1996-05-01

    Stronglink switches are a weapon surety device that is critical to the nuclear safety theme in modem nuclear weapons. These stronglink switches use rolling element bearings which contain a lubricant consisting of low molecular weight polytetrafluoroethylene (PTFE) fragments. Ozone-depleting solvents are used in both the manufacture and application of this lubricant. An alternate bearing lubrication for stronglink switches is needed that will provide long-term chemical stability, low migration and consistent performance. Candidates that were evaluated include bearings with sputtered MoS{sub 2} on the races and retainers, bearings with TiC-coated balls, and bearings with Si{sub 3}N{sub 4} balls and steel races. These candidates were compared to the lubricants currently used which are bearings lubricated with PTFE fragments of low molecular weight in a fluorocarbon solvent. The candidates were also compared to bearings lubricated with a diester oil which is representative of bearing lubricants used in industrial applications. Evaluation consisted of cycling preloaded bearings and subjecting them to 23 gRMS random vibration. All of the candidates are viable substitutes for low load application where bearing preload is approximately 1 pound. For high load applications where the bearing preload is approximately 10 pounds, bearings with sputtered MoS{sub 2} on the races and retainers appear to be the best substitutes. Bearings with TiC-coated balls also appear to be a viable candidate but these bearings did not perform as well as the sputtered MoS{sub 2}.

  2. Iron(III)-bearing clay minerals enhance bioreduction of nitrobenzene by Shewanella putrefaciens CN32.

    Science.gov (United States)

    Luan, Fubo; Liu, Yan; Griffin, Aron M; Gorski, Christopher A; Burgos, William D

    2015-02-03

    Iron-bearing clay minerals are ubiquitous in the environment, and the clay-Fe(II)/Fe(III) redox couple plays important roles in abiotic reduction of several classes of environmental contaminants. We investigated the role of Fe-bearing clay minerals on the bioreduction of nitrobenzene. In experiments with Shewanella putrefaciens CN32 and excess electron donor, we found that the Fe-bearing clay minerals montmorillonite SWy-2 and nontronite NAu-2 enhanced nitrobenzene bioreduction. On short time scales (<50 h), nitrobenzene reduction was primarily biologically driven, but at later time points, nitrobenzene reduction by biologically formed structural Fe(II) in the clay minerals became increasingly important. We found that chemically reduced (dithionite) iron-bearing clay minerals reduced nitrobenzene more rapidly than biologically reduced iron-bearing clay minerals despite the minerals having similar structural Fe(II) concentrations. We also found that chemically reduced NAu-2 reduced nitrobenzene faster as compared to chemically reduced SWy-2. The different reactivity of SWy-2 versus NAu-2 toward nitrobenzene was caused by different forms of structural clay-Fe(II) in the clay minerals and different reduction potentials (Eh) of the clay minerals. Because most contaminated aquifers become reduced via biological activity, the reactivity of biogenic clay-Fe(II) toward reducible contaminants is particularly important.

  3. Microstructure and Properties of Cast B-Bearing High Speed Steel

    Science.gov (United States)

    Fu, Hanguang; Ma, Shengqiang; Hou, Jianqiang; Lei, Yongping; Xing, Jiandong

    2013-04-01

    Microstructure, mechanical properties, and wear resistance of B-bearing high-speed steel (HSS) roll material containing 0.90-1.00% C, 1.3-1.5% B, 0.8-1.5% W, 0.8-1.5% Mo, 4.6-5.0% Cr, 1.0-1.2% V, and 0.15-0.20% Ti were studied by means of the optical microscopy (OM), the scanning electron microscopy (SEM), x-ray diffraction (XRD), hardness, impact toughness, and pin-on-disk abrasion tests. The results showed that as-cast structure of B-bearing HSS consisted of α-Fe-, M23(B,C)6-, M3(B0.7C0.3)-, and M2(B,C)-type borocarbides, a small quantity of retained austenite, and a small amount of TiC. The hardness and impact toughness values of as-cast B-bearing HSS reached 65-67 HRC and 80-85 kJ/cm2, respectively. There were many M23(B,C)6-precipitated phases in the matrix after tempering, and then, with increasing temperature, the amount of precipitated phases increased considerably. Hardness of B-bearing HSS gradually decreased with the increasing tempering temperature, and the change of tempering temperature had no obvious effect on impact toughness. B-bearing HSS tempered at 500 °C has excellent wear resistance, which can be attributed to the effect of boron.

  4. An investigation into failure analysis of interfering part of a steam turbine journal bearing

    Directory of Open Access Journals (Sweden)

    M. Mehdizadeh

    2014-10-01

    Full Text Available Journal bearings as so sensitive parts of steam turbines are very susceptible to failure through different mechanisms of wear, fatigue and crush during service conditions. Failure occurring through these mechanisms lead to turbine completely shut down as a result of interfering in working conditions of bearing different parts. In this research, failed interfered part of a journal bearing related to a 320,000 kW steam turbine was examined. Failure analysis investigations were performed by utilizing of stereographic, optical microscopy, scanning electron microscopy (SEM, energy-dispersive X-ray spectroscopy (EDS analysis and hardness test. Surface crush, large amounts of surface cracks, no noticeable changes of failed surface chemical composition and microstructure with significant hardness improvement were the main obtained results. The studies were revealed that the bearing part loosing and inappropriate clearance can produce relative displacements under cyclic gradient loading. This condition was detrimental for the service life of turbine journal bearing via failure through fretting fatigue mechanism.

  5. A Hydrostatic Bearing Test System for Measuring Bearing Load Using Magnetic-Fluid Lubricants.

    Science.gov (United States)

    Weng, Huei Chu; Chen, Lu-Yu

    2016-05-01

    This paper conducts a study on the design of a hydrostatic bearing test system. It involves the determination of viscous properties of magnetic-fluid lubricants. The load of a hydrostatic thrust bearing using a water-based magnetite nanofluid of varying volume flow rate is measured under an applied external induction field via the test system. Results reveal that the presence of nanoparticles in a carrier liquid would cause an enhanced bearing load. Such an effect could be further magnified by increasing the lubricant volume flow rate or the external induction field strength.

  6. NANO-BEARING: THE DESIGN OF A NEW TYPE OF AIR BEARING WITH FLEXURE STRUCTURE

    Institute of Scientific and Technical Information of China (English)

    KO Pui Hang; DU Ruxu

    2007-01-01

    A new type of air bearing with flexure structure is introduced. The new bearing is designed for precision mechanical engineering devices such as mechanical watch movement. The new design uses the flexure structure to provide 3D damping to absorb shocks from all directions. Two designs are presented: one has 12 T-shape slots in the radian direction while the other has 8 spiral slots in the radian direction. Both designs have flexure mountings on the axial directions. Based on the finite element analysis (FEA), the new bearing can reduce the vibration (displacement) by as much as 8.37% and hence, can better protect the shafts.

  7. Tests of Lead-bronze Bearings in the DVL Bearing-testing Machine

    Science.gov (United States)

    Fischer, G

    1940-01-01

    The lead-bronze bearings tested in the DVL machine have proven themselves very sensitive to load changes as in comparison with bearings of light metal. In order to prevent surface injuries and consequently running interruptions, the increase of the load has to be made in small steps with sufficient run-in time between steps. The absence of lead in the running surface, impurities in the alloy (especially iron) and surface irregularities (pores) decreases the load-carrying capacity of the bearing to two or three times that of the static load.

  8. Fault Tolerant Magnetic Bearing for Turbomachinery

    Science.gov (United States)

    Choi, Benjamin; Provenza, Andrew

    2001-01-01

    NASA Glenn Research Center (GRC) has developed a Fault-Tolerant Magnetic Bearing Suspension rig to enhance the bearing system safety. It successfully demonstrated that using only two active poles out of eight redundant poles from each radial bearing (that is, simply 12 out of 16 poles dead) levitated the rotor and spun it without losing stability and desired position up to the maximum allowable speed of 20,000 rpm. In this paper, it is demonstrated that as far as the summation of force vectors of the attracting poles and rotor weight is zero, a fault-tolerant magnetic bearing system maintained the rotor at the desired position without losing stability even at the maximum rotor speed. A proportional-integral-derivative (PID) controller generated autonomous corrective actions with no operator's input for the fault situations without losing load capacity in terms of rotor position. This paper also deals with a centralized modal controller to better control the dynamic behavior over system modes.

  9. Horizontal Air Bearing Experiment Number 1

    Energy Technology Data Exchange (ETDEWEB)

    Clauson, T.L.

    1999-08-31

    The Horizontal Air Bearing Experiment No.1 is a series of tests intended to further the understanding of rotational dynamics. A simple experimental assembly is rotated using the Horizontal Air Bearing and allowed to spin freely as the internal rotational damping is measured. The low friction of the bearing effectively isolates the test assembly, allowing the internal damping of the test object to be evaluated. The experimental assembly is composed of an aluminum ball within a spherical cavity. A flanged pipe section and an auxiliary adapter plate secure the assembly to the Air Bearing interface plate. Three aluminum balls are interchanged to vary test parameters. The aluminum balls are free to move independently as the entire assembly rotates. The aluminum balls vary in diameter and/or surface finish. While the diameter and surface finish is varied, the space between the ball and socket is dry. To examine the effect of viscosity, the space is filled with a lubricant while the ball diameter and surface finish is held constant.

  10. The economics of roadside bear viewing

    Science.gov (United States)

    Richardson, Leslie; Rosen, Tatjana; Gunther, Kerry; Schwartz, Chuck

    2014-01-01

    Viewing bears along roadside habitats is a popular recreational activity in certain national parks throughout the United States. However, safely managing visitors during traffic jams that result from this activity often requires the use of limited park resources. Using unique visitor survey data, this study quantifies economic values associated with roadside bear viewing in Yellowstone National Park, monetary values that could be used to determine whether this continued use of park resources is warranted on economic grounds. Based on visitor expenditure data and results of a contingent visitation question, it is estimated that summer Park visitation would decrease if bears were no longer allowed to stay along roadside habitats, resulting in a loss of 155 jobs in the local economy. Results from a nonmarket valuation survey question indicate that on average, visitors to Yellowstone National Park are willing to pay around $41 more in Park entrance fees to ensure that bears are allowed to remain along roads within the Park. Generalizing this value to the relevant population of visitors indicates that the economic benefits of allowing this wildlife viewing opportunity to continue could outweigh the costs of using additional resources to effectively manage these traffic jams.

  11. On Controllable Elastohydrodynamic Fluid Film Bearings

    DEFF Research Database (Denmark)

    Haugaard, Martin Asger

    This thesis gives a theoretical description of the active tilting-pad journal bearing (ATPJB). It provides the qualified reader with the tools to model an ATPJB, while staying clear of pitfalls. The model is based on well known techniques and allows for local stability analyses, harmonic stationa...

  12. Heavy Bearings Exploitation Energy and Reduction Methods

    Science.gov (United States)

    Szekely, V. G.; Cioară, R.

    2016-11-01

    The global trend of resource conservation so as “not to compromise the ability of future generation's development” is the fundamental basis of the concept of sustainable development. Concordant with this, the energy efficiency of products is increasingly discussed and frequently taken into account in the design stage. In more cases a product is more appreciated and more attractive as the energy consumption and its associated materials are lower. In the production stage, said consumption advantages primarily the manufacturer, particularly through low consumption thereof. In the operational phase, low energy and materials consumption represents an user advantage and it's a major argument in the decision to purchase and use a particular product. Heavy bearings are frequent products used in wind turbines that are producing non-conventional “clean” energy, as windmills. An enhanced energy efficiency bearing contributes to the enhancement of the overall efficiency of the wind turbines. Based on a suitable mathematical model, this paper identifies and recommends courses of action to reduce the operating energy of heavy bearing through the “cage” - which is the subject of a much larger research - with the highest priority. The identified actions may constitute from a set of requirements for the design stage of the heavy bearing predominantly oriented towards innovation-invention.

  13. Angular-momentum-bearing modes in fission

    Energy Technology Data Exchange (ETDEWEB)

    Moretto, L.G.; Peaslee, G.F.; Wozniak, G.J.

    1989-03-01

    The angular-momentum-bearing degrees of freedom involved in the fission process are identified and their influence on experimental observables is discussed. The excitation of these modes is treated in the ''thermal'' limit, and the resulting distributions of observables are calculated. Experiments demonstrating the role of these modes are presented and discussed. 61 refs., 12 figs.

  14. Load Bearing Equipment for Bone and Muscle

    Science.gov (United States)

    Shackelford, Linda; Griffith, Bryan

    2015-01-01

    Resistance exercise on ISS has proven effective in maintaining bone mineral density and muscle mass. Exploration missions require exercise with similar high loads using equipment with less mass and volume and greater safety and reliability than resistance exercise equipment used on ISS (iRED, ARED, FWED). Load Bearing Equipment (LBE) uses each exercising person to create and control the load to the partner.

  15. Ball bearing measurement with white light interferometry

    Science.gov (United States)

    Schmit, Joanna; Han, Sen; Novak, Erik

    2009-06-01

    Requirements on high-performance of ball bearings in terms of the loads they experience and their reliability are increasing as the automotive, aerospace, and power generation industries look to cut costs, reduce emissions, and improve efficiency. Most bearings are evaluated with a stylus profiler or with a bright field scopes or microscopes for form, roughness, and defect classification. Two-dimensional stylus measurements captures only very localized surface profiles unless multiple scans are performed which slow the measurement time unacceptably; this leads to inadequate sampling and sometimes greatly varying results based on location and directionality of the line scan. Bright field microscopes deliver only the lateral information about defects but not their depth, volume or surface roughness. White light interferometry can be very successfully utilized in the measurement of full field form, roughness and defect detection and is gaining adoption. They provide rapid, accurate, three-dimensional imaging compatible with the newly developed ISO 3D surface parameters which are expected to rapidly displace traditional 2D metrics. These surface parameters allow for better characterization of surface structure and better understanding of the production process and bearing and race wear. New 3D filtering techniques allow effective separation of form, waviness, and roughness for highly accurate and repeatable bearing qualification.

  16. MAGNETIC FLUID BEARINGS OF MINING EQUIPMENT

    Directory of Open Access Journals (Sweden)

    I. Gorlov

    2012-01-01

    Full Text Available The paper considers a problem pertaining to selection friction pair materials for plain bearings of mining equipment which are lubricated with  nano-dispersed magnetic oil. Methodology for equipment tests, technology for obtaining new anti-friction materials (polymer, ceramic, amorphous and investigation results are presented in the paper.

  17. Load-Bearing Capacity of Roof Trusses

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Damkilde, Lars; Munch-Andersen, J.

    2004-01-01

    systems such as roof trusses are established and statistical characteristics of the load bearing capacity are determined. The results show that there is a significant increase in the characteristic (nominal) value and a reduction in the coefficient of variation (COV) for typical loads such as permanent...

  18. Extended Life Testing of Duplex Ball Bearings

    Science.gov (United States)

    Mobley, Jeffrey; Robertson, Michael; Hodges, Charles

    2016-01-01

    Sierra Nevada Corporation’s Space Systems performed bearing life testing for the Scan Mirror Motor/Encoder Assembly (SMMA), part of the Scan Mirror Assembly on-board the Aerosol Polarimetry Sensor (APS) on the NASA Glory Spacecraft. The baseline bearing life test duration extended beyond the launch date for the Glory Spacecraft; a risk that the program was willing to undertake with the understanding that if any anomalies or failures occurred before the required life was achieved, then the mission objectives or operating profile could be modified on orbit to take those results into account. Even though the Glory Spacecraft failed to reach orbit during its launch in March of 2011, the bearing life testing was continued through a mutual understanding of value between Sierra Nevada Corporation and our customer; with a revised goal of testing to failure rather than completing a required number of life cycles. Life testing thus far has not only exceeded the original mission required life, but has also exceeded the published test data for Cumulative Degradation Factor (CDF) from NASA/CR-2009-215681. Many lessons were learned along the way regarding long life testing. The bearing life test has been temporarily suspended due to test support equipment issues.

  19. Bearings and Seals. FOS: Fundamentals of Service.

    Science.gov (United States)

    John Deere Co., Moline, IL.

    This manual on bearings and seals is one of a series of power mechanics texts and visual aids for use in training for the servicing of automotive and off-the-road farm and industrial machines. Materials provide basic information and illustrations for use by vocational students and teachers as well as shop servicemen and laymen. Focusing on…

  20. Active Magnetic Bearings. Postgraduate Seminar on Electromechanics

    Energy Technology Data Exchange (ETDEWEB)

    Lantto, E.; Tommila, V.; Arkkio, A.

    2007-07-01

    The papers in the seminar on electromagnetics are published only as power point slides. The titles of the different papers are: Introduction to magnetic bearings, Magnetic field and forces, Actuators, amplifiers and sensors, System theory, rotordynamics and control, Diagnostics, applications and standardisation.

  1. Annular Pressure Seals and Hydrostatic Bearings

    Science.gov (United States)

    2006-11-01

    affecting the rotordynamics of liquid turbopumps, in particular those handling large density fluids. Highlights on the bulk-flow analysis of annular seals... rotordynamic stability. Hydrostatic bearings rely on external fluid pressurization to generate load support and large centering stiffnesses, even in...SEALS IN PUMP APPLICATIONS Seal rotordynamic characteristic have a primary influence on the stability response of high-performance turbomachinery [1

  2. Carbide Dissolution during Intercritical Austenitization in Bearing Steel

    Institute of Scientific and Technical Information of China (English)

    LI Hui; MI Zhenli; ZHANG Xiaolei; TANG Di; WANG Yide

    2014-01-01

    In order to investigate the carbide dissolution mechanism of high carbon-chromium bearing steel during the intercritical austenitization, the database of TCFE7 of Thermo-calc and MOBFE of DICTRA software were used to calculate the elements diffusion kinetic and the evolution law of volume fraction of carbide. DIL805A dilatometer was used to simulate the intercritical heat treatment. The microstructure was observed by scanning electron microscopy(SEM), and the micro-hardness was tested. The experimental results indicate that the dissolution of carbide is composed of two stages:initial austenite growth governed by carbon diffusion which sharply moves up the micro-hardness of quenched martensite, and subsequent growth controlled by diffusion of Cr elements in M3C. The volume fraction of M3C decreases with the increasing holding time, and the metallographic analysis shows a great agreement with values calculated by software.

  3. Magnetic Bearing Controller Improvements for High Speed Flywheel System

    Science.gov (United States)

    Dever, Timothy P.; Brown, Gerald V.; Jansen, Ralph H.; Kascak, Peter E.; Provenza, Andrew J.

    2003-01-01

    A magnetic bearing control system for a high-speed flywheel system is described. The flywheel utilizes a five axis active magnetic bearing system, using eddy current sensors for position feedback to the bearing controller. Magnetic bearing controller features designed to improve flywheel operation and testing are described. Operational improvements include feed forward control to compensate for rotor imbalance, moving notch filtering to compensate for synchronous and harmonic rotational noise, and fixed notching to prevent rotor bending mode excitation. Testing improvements include adding safe gain, bearing current hold, bearing current zero, and excitation input features. Performance and testing improvements provided by these features are measured and discussed.

  4. Direct Model Reference Adaptive Control for a Magnetic Bearing

    Energy Technology Data Exchange (ETDEWEB)

    Durling, Mike [Rensselaer Polytechnic Inst., Troy, NY (United States)

    1999-11-01

    A Direct Model Reference Adaptive Controller (DMRAC) is applied to a magnetic bearing test stand. The bearing of interest is the MBC 500 Magnetic Bearing System manufactured by Magnetic Moments, LLC. The bearing model is presented in state space form and the system transfer function is measured directly using a closed-loop swept sine technique. Next, the bearing models are used to design a phase-lead controller, notch filter and then a DMRAC. The controllers are tuned in simulations and finally are implemented using a combination of MATLAB, SIMULINK and dSPACE. The results show a successful implementation of a DMRAC on the magnetic bearing hardware.

  5. Grievous Temporal and Occipital Injury Caused by a Bear Attack

    Directory of Open Access Journals (Sweden)

    Sampath Chandra Prasad

    2013-01-01

    Full Text Available Bear attacks are reported from nearly every part of the world. The chance of a human encountering a bear increases as the remote bear territory diminishes. The sloth bear is one of the three species of bears found in India, which inhabits the forests of India and its neighboring countries. Here we describe a teenager who came to us with a critical injury involving the face, temporal and occipital bones inflicted by a sloth bear attack. He underwent a temporal exploration, facial nerve decompression, pinna reconstruction, and occipital bone repair to save him from fatality.

  6. Blade Bearing Friction Estimation of Operating Wind Turbines

    DEFF Research Database (Denmark)

    Perisic, Nevena; Pedersen, Bo Juul; Kirkegaard, Poul Henning

    2012-01-01

    Blade root bearing on a wind turbine (WTG) enables pitching of blades for power control and rotor braking and is a WTG critical component. As the size of modern WTGs is constantly increasing, this leads to relatively less rigid bearings, more sensitive to deformations, thus WTG operational...... reliability can be increased by continuous monitoring of blade bearing. High blade bearing friction is undesirable, as it may be associated with excessive heating of the surfaces, damage and/or inefficient operation. Thus, continuous observation of bearing friction level is crucial for blade bearing health...

  7. A Spaceflight Magnetic Bearing Equipped Optical Chopper with Six-Axis Active Control

    Science.gov (United States)

    Blumenstock, Kenneth A.; Lee, Kenneth Y.; Schepis, Joseph P.

    1998-01-01

    This paper describes the development of an ETU (Engineering Test Unit) rotary optical chopper with magnetic bearings. An ETU is required to be both flight-like, nearly identical to a flight unit without the need for material certifications, and demonstrate structural and performance integrity. A prototype breadboard design previously demonstrated the feasibility of meeting flight performance requirements using magnetic bearings. The chopper mechanism is a critical component of the High Resolution Dynamics Limb Sounder (HIRDLS) which will be flown on EOS-CHEM (Earth Observing System-Chemistry). Particularly noteworthy are the science requirements which demand high precision positioning and minimal power consumption along with full redundancy of coils and sensors in a miniature, lightweight package. The magnetic bearings are unique in their pole design to minimize parasitic losses and utilize collocated optical sensing. The motor is of an unusual disk-type ironless stator design. The ETU design has evolved from the breadboard design. A number of improvements have been incorporated into the ETU design. Active thrust control has been added along with changes to improve sensor stability, motor efficiency, and touchdown and launch survivability. It was necessary to do all this while simultaneously reducing the mechanism volume. Flight-like electronics utilize a DSP (Digital Signal Processor) and contain all sensor electronics and drivers on a single five inch by nine inch circuit board. Performance test results are reported including magnetic bearing and motor rotational losses.

  8. Hard electronics; Hard electronics

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    In the fields of power conversion devices and broadcasting/communication amplifiers, high power, high frequency and low losses are desirable. Further, for electronic elements in aerospace/aeronautical/geothermal surveys, etc., heat resistance to 500degC is required. Devices which respond to such hard specifications are called hard electronic devices. However, with Si which is at the core of the present electronics, the specifications cannot fully be fulfilled because of the restrictions arising from physical values. Accordingly, taking up new device materials/structures necessary to construct hard electronics, technologies to develop these to a level of IC were examined and studied. They are a technology to make devices/IC of new semiconductors such as SiC, diamond, etc. which can handle higher temperature, higher power and higher frequency than Si and also is possible of reducing losses, a technology to make devices of hard semiconducter materials such as a vacuum microelectronics technology using ultra-micro/high-luminance electronic emitter using negative electron affinity which diamond, etc. have, a technology to make devices of oxides which have various electric properties, etc. 321 refs., 194 figs., 8 tabs.

  9. Submicro-battery effect and selective bio-oxidation model of gold-bearing arsenopyrite by Thiobacillus ferrooxidans

    Institute of Scientific and Technical Information of China (English)

    杨洪英; 杨立; 赵玉山; 陈刚; 吕久吉; 范有静

    2002-01-01

    Through the study by electronic probe it was found that many new cracks and holes appear on the surface of gold-bearing arsenopyrite crystal oxidized by Thiobacillus ferrooxidans, which are along with some directions. Then the selective bio-oxidation model of gold-bearing arsenopyrite was set up. The selective bio-oxidation resulting from the submicro-battery effect of gold/ arsenopyrite mineral pairs naturally forms in the gold-bearing arsenopyrite crystal. Thiobacillus ferrooxidans has priority to oxidize the place of gold-rich and oxidizes selectedly along with the crystal border, crystal face and crack. The bacteria oxidation process of gold-bearing arsenopyrite is divided into three stages: the first stage is the surface oxidation, the second stage is restraining oxidation and the third stage is the filament oxidation, bacteria oxidize along with cracks of arsenopyrite.

  10. Kenai Peninsula Brown Bear Studies : Report of the Interagency Brown Bear Study Team, 1986

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report summarizes work conducted during the 1986 field season on brown bear (Ursus arctos) from the Kenai Peninsula, Alaska. Ground surveys were conducted to...

  11. Rotor Bearing System Analysis Using the Transfer Matrix Method with Thickness Assumption of Disk and Bearing

    CERN Document Server

    Ghasemalizadeh, Omid; Sadeghi, Hossein; Ahmadian, Mohammad Taghi

    2013-01-01

    One of the methods to find the natural frequencies of rotating systems is the application of the transfer matrix method. In this method the rotor is modeled as several elements along the shaft which have their own mass and moment of inertia. Using these elements, the entire continuous system is discretized and the corresponding differential equation can be stated in matrix form. The bearings at the end of the shaft are modeled as equivalent spring and dampers which are applied as boundary conditions to the discretized system. In this paper the dynamics of a rotor-bearing system is analyzed, considering the gyroscopic effect. The thickness of the disk and bearings is also taken into account. Continuous model is used for shaft. Results Show that, the stiffness of the shaft and the natural frequencies of the system increase, while the amplitude of vibration decreases as a consequence of increasing the thickness of the bearing.

  12. Adaptation of the hindlimbs for climbing in bears.

    Science.gov (United States)

    Sasaki, Motoki; Endo, Hideki; Wiig, Oystein; Derocher, Andrew E; Tsubota, Toshio; Taru, Hajime; Yamamoto, Masako; Arishima, Kazuyoshi; Hayashi, Yoshihiro; Kitamura, Nobuo; Yamada, Junzo

    2005-04-01

    The hindlimbs of the Malayan sun bear (Helarctos malayanus), the polar bear (Ursus maritimus), the brown bear (Ursus arctos) and the giant panda (Ailuropoda melanoleuca) have been anatomically and osteometrically studied. The Musculus tibialis cranialis of the Malayan sun bear and the giant panda possessed a well-developed rich fleshy portion until the distal end of the tibia. In the polar bear and the brown bear, however, the fleshy portion of the M. tibialis cranialis was not developed until the distal end of the tibia. The tendon of the M. tibialis cranialis inserting on the proximal end of the Ossa metatarsalia was shorter in the Malayan sun bear and the giant panda than in the polar bear and the brown bear. In the Malayan sun bear and the giant panda, moreover, the M. popliteus was attached more distally to the tibia than in the polar bear and the brown bear. The stable dorsiflexion and supination of the foot and the efficient pronation of the crus are important for skillful tree climbing. The present study suggests that the Malayan sun bear and the giant panda have hindlimbs especially adapted to tree climbing by the well-developed fleshy portion of the M. tibialis cranialis reaching the distal end of the tibia, its short tendon, and the M. popliteus inserting near the distal end of the tibia.

  13. Electronic Cigarettes

    Science.gov (United States)

    ... New FDA Regulations Text Size: A A A Electronic Cigarettes Electronic cigarettes (e-cigarettes) are battery operated products designed ... more about: The latest news and events about electronic cigarettes on this FDA page Electronic cigarette basics ...

  14. THE STRUCTURAL ANALYSIS OF STEEL SILOS WITH CYLINDRICAL-WALL BEARING AND PROFILE-STEEL BEARING

    OpenAIRE

    Zhengjun Tang; Daibiao Zhou; Chenwei Peng; Wenping Wu

    2015-01-01

    The silos are widely used in bulk material in many fields such as agriculture, mining, chemical, electric power storage, etc. Thin metal cylindrical silo shells are vulnerable to buckling failure caused by the compressive wall friction force. In this paper, the structural analysis of two types of steel silo with cylindrical-wall bearing and profile-steel bearing is implemented by Abaqus finite element analysis. The results indicate that under the same loading conditions, steel silos with prof...

  15. The Electron

    Energy Technology Data Exchange (ETDEWEB)

    Thomson, George

    1972-01-01

    Electrons are elementary particles of atoms that revolve around and outside the nucleus and have a negative charge. This booklet discusses how electrons relate to electricity, some applications of electrons, electrons as waves, electrons in atoms and solids, the electron microscope, among other things.

  16. Rolling element bearing diagnostics—A tutorial

    Science.gov (United States)

    Randall, Robert B.; Antoni, Jérôme

    2011-02-01

    This tutorial is intended to guide the reader in the diagnostic analysis of acceleration signals from rolling element bearings, in particular in the presence of strong masking signals from other machine components such as gears. Rather than being a review of all the current literature on bearing diagnostics, its purpose is to explain the background for a very powerful procedure which is successful in the majority of cases. The latter contention is illustrated by the application to a number of very different case histories, from very low speed to very high speed machines. The specific characteristics of rolling element bearing signals are explained in great detail, in particular the fact that they are not periodic, but stochastic, a fact which allows them to be separated from deterministic signals such as from gears. They can be modelled as cyclostationary for some purposes, but are in fact not strictly cyclostationary (at least for localised defects) so the term pseudo-cyclostationary has been coined. An appendix on cyclostationarity is included. A number of techniques are described for the separation, of which the discrete/random separation (DRS) method is usually most efficient. This sometimes requires the effects of small speed fluctuations to be removed in advance, which can be achieved by order tracking, and so this topic is also amplified in an appendix. Signals from localised faults in bearings are impulsive, at least at the source, so techniques are described to identify the frequency bands in which this impulsivity is most marked, using spectral kurtosis. For very high speed bearings, the impulse responses elicited by the sharp impacts in the bearings may have a comparable length to their separation, and the minimum entropy deconvolution technique may be found useful to remove the smearing effects of the (unknown) transmission path. The final diagnosis is based on "envelope analysis" of the optimally filtered signal, but despite the fact that this

  17. Hard electronics; Hard electronics

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-03-01

    Hard material technologies were surveyed to establish the hard electronic technology which offers superior characteristics under hard operational or environmental conditions as compared with conventional Si devices. The following technologies were separately surveyed: (1) The device and integration technologies of wide gap hard semiconductors such as SiC, diamond and nitride, (2) The technology of hard semiconductor devices for vacuum micro- electronics technology, and (3) The technology of hard new material devices for oxides. The formation technology of oxide thin films made remarkable progress after discovery of oxide superconductor materials, resulting in development of an atomic layer growth method and mist deposition method. This leading research is expected to solve such issues difficult to be easily realized by current Si technology as high-power, high-frequency and low-loss devices in power electronics, high temperature-proof and radiation-proof devices in ultimate electronics, and high-speed and dense- integrated devices in information electronics. 432 refs., 136 figs., 15 tabs.

  18. Assessing the redox properties of iron-bearing clay minerals using homogeneous electrocatalysis

    Energy Technology Data Exchange (ETDEWEB)

    Gorski, Christopher A., E-mail: Christopher.gorski@eawag.ch [Environmental Chemistry, Eawag, Swiss Federal Institute of Aquatic Science and Technology, Uberlandstrasse 133, P.O. Box 611, 8600 Duebendorf (Switzerland); Sander, Michael; Aeschbacher, Michael [Institute of Biogeochemistry and Pollutant Dynamics (IBP), ETH Zurich, Universitaetstrasse 16, 8092 Zuerich (Switzerland); Hofstetter, Thomas B. [Environmental Chemistry, Eawag, Swiss Federal Institute of Aquatic Science and Technology, Uberlandstrasse 133, P.O. Box 611, 8600 Duebendorf (Switzerland)] [Institute of Biogeochemistry and Pollutant Dynamics (IBP), ETH Zurich, Universitaetstrasse 16, 8092 Zuerich (Switzerland)

    2011-06-15

    Iron-bearing clay minerals are ubiquitous in the environment and have been shown to play important roles in several biogeochemical processes. Previous efforts to characterize the Fe{sup 2+}-Fe{sup 3+} redox couple in clay minerals using electrochemical techniques have been limited by experimental difficulties due to inadequate reactivity between clay minerals and electrodes. The current work overcomes this limitation by utilizing organic electron transfer mediators that rapidly transfer electrons with both the Fe-bearing clay minerals and electrodes. Here, an Fe-rich source clay mineral (ferruginous smectite, SWa-1) is examined with respect to what fraction of structural Fe participates in oxidation/reduction reactions and the relationship between bulk Fe{sup 2+}/Fe{sup 3+} ratios to the reduction potential (E{sub h}).

  19. Investigation of tribological and mechanical properties of metal bearings

    Indian Academy of Sciences (India)

    Bekir Sadik Ünlü

    2009-08-01

    Copper, aluminum and tin–lead based alloys are widely used as journal bearing materials in tribological applications. Bronze and brass are widely used as journal bearing materials for copper based alloys. Zamacs find applications as journal bearing materials for zinc based alloys, while duralumines are chosen as journal bearing materials for aluminum based alloys. In addition, white metals are widely used as journal bearing materials for tin–lead based alloys. These alloys ensure properties expected from journal bearings. In this study, tribological and mechanical properties of these journal bearings manufactured by metals were investigated. SAE 1050 steel shaft was used as counter abrader. Experiments were carried out in every 30 min for a total of 150 min by using radial journal bearing wear test rig.

  20. Land protection plan : Bear River Watershed Conservation Area

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The U.S. Fish and Wildlife Service is establishing a conservation area for the Bear River watershed in Idaho, Utah, and Wyoming. The Bear River Watershed...