Science.gov

Sample records for beaver valley-2 reactor

  1. Beaver herbivory on aquatic plants.

    PubMed

    Parker, John D; Caudill, Christopher C; Hay, Mark E

    2007-04-01

    Herbivores have strong impacts on marine and terrestrial plant communities, but their impact is less well studied in benthic freshwater systems. For example, North American beavers (Castor canadensis) eat both woody and non-woody plants and focus almost exclusively on the latter in summer months, yet their impacts on non-woody plants are generally attributed to ecosystem engineering rather than herbivory. Here, we excluded beavers from areas of two beaver wetlands for over 2 years and demonstrated that beaver herbivory reduced aquatic plant biomass by 60%, plant litter by 75%, and dramatically shifted plant species composition. The perennial forb lizard's tail (Saururus cernuus) comprised less than 5% of plant biomass in areas open to beaver grazing but greater than 50% of plant biomass in beaver exclusions. This shift was likely due to direct herbivory, as beavers preferentially consumed lizard's tail over other plants in a field feeding assay. Beaver herbivory also reduced the abundance of the invasive aquatic plant Myriophyllum aquaticum by nearly 90%, consistent with recent evidence that native generalist herbivores provide biotic resistance against exotic plant invasions. Beaver herbivory also had indirect effects on plant interactions in this community. The palatable plant lizard's tail was 3 times more frequent and 10 times more abundant inside woolgrass (Scirpus cyperinus) tussocks than in spatially paired locations lacking tussocks. When the protective foliage of the woolgrass was removed without exclusion cages, beavers consumed nearly half of the lizard's tail leaves within 2 weeks. In contrast, leaf abundance increased by 73-93% in the treatments retaining woolgrass or protected by a cage. Thus, woolgrass tussocks were as effective as cages at excluding beaver foraging and provided lizard's tail plants an associational refuge from beaver herbivory. These results suggest that beaver herbivory has strong direct and indirect impacts on populations and

  2. Beaver assisted river valley formation

    USGS Publications Warehouse

    Westbrook, C.J.; Cooper, D.J.; Baker, B.W.

    2011-01-01

    We examined how beaver dams affect key ecosystem processes, including pattern and process of sediment deposition, the composition and spatial pattern of vegetation, and nutrient loading and processing. We provide new evidence for the formation of heterogeneous beaver meadows on riverine system floodplains and terraces where dynamic flows are capable of breaching in-channel beaver dams. Our data show a 1.7-m high beaver dam triggered overbank flooding that drowned vegetation in areas deeply flooded, deposited nutrient-rich sediment in a spatially heterogeneous pattern on the floodplain and terrace, and scoured soils in other areas. The site quickly de-watered following the dam breach by high stream flows, protecting the deposited sediment from future re-mobilization by overbank floods. Bare sediment either exposed by scouring or deposited by the beaver flood was quickly colonized by a spatially heterogeneous plant community, forming a beaver meadow. Many willow and some aspen seedlings established in the more heavily disturbed areas, suggesting the site may succeed to a willow carr plant community suitable for future beaver re-occupation. We expand existing theory beyond the beaver pond to include terraces within valleys. This more fully explains how beavers can help drive the formation of alluvial valleys and their complex vegetation patterns as was first postulated by Ruedemann and Schoonmaker in 1938. ?? 2010 John Wiley & Sons, Ltd.

  3. The Buried Town of Beaver.

    ERIC Educational Resources Information Center

    Jostad, Karen

    Local history as source material for environmental education is uniquely portrayed in this resource kit. Utilizing a Winona County Historical Society publication, "The Beaver Story" and accompanied by a teacher's guide, "The Buried Town of Beaver," and other teaching aids, a case study of the area can be developed. Based on the reminiscences of…

  4. The Beaver Creek story

    USGS Publications Warehouse

    Doyle, W.H.; Whitworth, B.G.; Smith, G.F.; Byl, T.D.

    1996-01-01

    Beaver Creek watershed in West Tennessee includes about 95,000 acres of the Nation's most productive farmland and most highly erodible soils. In 1989 the U.S. Geological Survey, in cooperation with the Tennessee Department of Agriculture, began a study to evaluate the effect of agricultural activities on water quality in the watershed and for best management practices designed to reduce agricultural nonpoint-source pollution. Agrichemical monitoring included testing the soils, ground water, and streams at four farm sites ranging from 27 to 420 acres. Monitoring stations were operated downstream to gain a better understanding of the water chemistry as runoff moved from small ditches into larger streams to the outlet of the Beaver Creek watershed. Prior to the implementation of best management practices at one of the farm study sites, some storms produced an average suspended-sediment concentration of 70,000 milligrams per liter. After the implementation of BMP's, however, the average value never exceeded 7,000 milligrams per liter. No-till crop production was the most effective best management practice for conserving soil on the farm fields tested. A natural bottomland hardwood wetland and a constructed wetland were evaluated as instream resource-management systems. The wetlands improved water quality downstream by acting as a filter and removing a significant amount of nonpoint-source pollution from the agricultural runoff. The constructed wetland reduced the sediment, pesticide, and nutrient load by approximately 50 percent over a 4-month period. The results of the Beaver Creek watershed study have increased the understanding of the effects of agriculture on water resources. Study results also demonstrated that BMP's do protect and improve water quality.

  5. Can Viral Videos Help Beaver Restore Streams?

    NASA Astrophysics Data System (ADS)

    Castro, J. M.; Pollock, M. M.; Lewallen, G.; Jordan, C.; Woodruff, K.

    2015-12-01

    Have you watched YouTube lately? Did you notice the plethora of cute animal videos? Researchers, including members of our Beaver Restoration Research team, have been studying the restoration potential of beaver for decades, yet in the past few years, beaver have gained broad acclaim and some much deserved credit for restoration of aquatic systems in North America. Is it because people can now see these charismatic critters in action from the comfort of their laptops? While the newly released Beaver Restoration Guidebook attempts to answer many questions, sadly, this is not one of them. We do, however, address the use of beaver (Castor canadensis) in stream, wetland, and floodplain restoration and discuss the many positive effects of beaver on fluvial ecosystems. Our team, composed of researchers from NOAA National Marine Fisheries Service, US Fish and Wildlife Service, US Forest Service, and Portland State University, has developed a scientifically rigorous, yet accessible, practitioner's guide that provides a synthesis of the best available science for using beaver to improve ecosystem functions. Divided into two broad sections -- Beaver Ecology and Beaver Restoration and Management -- the guidebook focuses on the many ways in which beaver improve habitat, primarily through the construction of dams that impound water and retain sediment. In Beaver Ecology, we open with a discussion of the general effects that beaver dams have on physical and biological processes, and we close with "Frequently Asked Questions" and "Myth Busters". In Restoration and Management, we discuss common emerging restoration techniques and methods for mitigating unwanted beaver effects, followed by case studies from pioneering practitioners who have used many of these beaver restoration techniques in the field. The lessons they have learned will help guide future restoration efforts. We have also included a comprehensive beaver ecology library of over 1400 references from scientific journals

  6. Habitat Suitability Index Models: Beaver

    USGS Publications Warehouse

    Allen, Arthur W.

    1982-01-01

    Habitat preferences of the beaver (Castor canadensis) are described in this publication, which is one of a series of Habitat Suitability Index (HSI) models. Habitat use information is presented in a synthesis of the literature on the species-habitat requirements of the beaver, followed by the development of the HSI model. The model is designed to provide information for use in impact assessment and habitat management activities, and should be used in conjunction with habitat evaluation procedures previously developed by the Fish and Wildlife Service. This revised model updates the original publication dated September 1982.

  7. Early postglacial beavers in southeastern New England

    USGS Publications Warehouse

    Kaye, C.A.

    1962-01-01

    Wood cut by Castor canadensis(?) has been found at or near the base of five peat deposits studied in open exposure. Beavers apparently entered the region about 12,000 years ago and rapidly occupied most low-lying places. Many existing bogs may be the result of early dams. The disturbance of pond sediments by beavers probably affects pollen stratigraphy. Charred wood in early beaver structures indicates forest fires and the possibility that the climate was drier than it is today.

  8. Left panel of panoramic overview of Beaver River Bridge and ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Left panel of panoramic overview of Beaver River Bridge and New Brighton, looking NE from Patterson Heights, abuts PA-511-2 - Pittsburgh, Fort Wayne & Chicago Railway, Beaver River Bridge, Spanning Beaver River along line of Second Avenue, New Brighton, Beaver County, PA

  9. Right panel of panoramic overview of Beaver River Bridge and ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Right panel of panoramic overview of Beaver River Bridge and New Brighton, looking SE from Patternson Heights, abuts PA-511-1. - Pittsburgh, Fort Wayne & Chicago Railway, Beaver River Bridge, Spanning Beaver River along line of Second Avenue, New Brighton, Beaver County, PA

  10. 63. REACTOR CHAMBER (BASF) FROM NORTH SHOWING NEUTRON SHIELD TANK ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    63. REACTOR CHAMBER (BASF) FROM NORTH SHOWING NEUTRON SHIELD TANK AND REACTOR PIPING (LOCATION RRR) - Shippingport Atomic Power Station, On Ohio River, 25 miles Northwest of Pittsburgh, Shippingport, Beaver County, PA

  11. Captive care and welfare considerations for beavers.

    PubMed

    Campbell-Palmer, Róisín; Rosell, Frank

    2015-01-01

    Beavers (Castor spp.) tend not to be a commonly held species and little published material exists relating to their captive care. We review published material and discuss husbandry issues taking into account the requirements of wild beavers. As social mammals with complex chemical communication systems and with such an ability to modify their environments, studies of wild counterparts suggest the captive requirements of beavers may actually be more sophisticated than generally perceived. Common field techniques may have practical application in the captive setting. Their widespread utilisation in conservation, including reintroductions, translocations and habitat management, also requires components of captive care. As welfare science advances there is increasing pressure on captive collections to improve standards and justify the keeping of animals. Conservation science is increasingly challenged to address individual welfare standards. Further research focusing on the captive care of beavers is required.

  12. A Seniors' Program for Beaver County

    ERIC Educational Resources Information Center

    Taylor, Donald F.

    1973-01-01

    Programs for seniors are needed, according to the assistant director of continuing education at the Community College of Beaver County (Pennsylvania); the question revolves around who will pay. (Editor)

  13. 1. INTAKE CHANNEL LOOKING NORTHEAST; WATER FROM BEAVER BROOK ENTERS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. INTAKE CHANNEL LOOKING NORTHEAST; WATER FROM BEAVER BROOK ENTERS THE INTAKE CHANNEL HERE. - Hondius Water Line, 1.6 miles Northwest of Park headquarters building & 1 mile Northwest of Beaver Meadows entrance station, Estes Park, Larimer County, CO

  14. Experimental habitat scenting inhibits colonization by beaver,Castor canadensis.

    PubMed

    Gregory Welsh, R; Muller-Schwarze, D

    1989-03-01

    Unoccupied beaver (Castor canadensis) sites in New York State were for two years experimentally scented with a mixture of beaver castoreum and anal gland secretion. These sites were colonized less often than unscented control sites. The beaver is the first mammal to have been shown experimentally to use intraspecific odor cues when settling in vacant habitat. Territorial pheromones may be useful as repellents for beaver or other rodents.

  15. Water resources of Beaver Valley, Utah

    USGS Publications Warehouse

    Lee, Willis Thomas

    1908-01-01

    Location and extent of area examined. Beaver Valley is located in Beaver County, in southwestern Utah, about 175 miles south of Salt Lake. It lies between the Tushar Mountains on the east and the Beaver Mountains on the west. The principal town of the valley is Beaver, which is most conveniently reached from Milford, a station on the San Pedro, Los Angeles and Salt Lake Railroad. The valley, together with its neighboring highlands, occupies the eastern third of Beaver County, an area of about 1,200 square miles. A large part of this area, however, is rocky upland and unproductive desert, the tillable land comprising a comparatively small area in the immediate vicinity of the streams.Purpose and scope of work. The purpose of this paper is to present information concerning the waters of Beaver Valley and to point out ways and means of increasing their usefulness. The presence of a large amount of water in Beaver Valley results from local topograhic conditions, the water being supplied by precipitation in the highland to the east. Its conservation and distribution result from geologic conditions, the water being held in loose gravel and sand, which are more or less confined between ridges of consolidated rocks. The rock basins were formed partly by erosion and partly by faulting and surface deformation. In order to accomplish the purpose in view it is therefore necessary to describe the geographic and geologic conditions in Beaver Valley and neighboring regions.The investigation included the determination of the flow of streams and springs, of the manner of occurrence and quantity of the underground waters as shown by the geologic and geographic conditions of the region and by the distribution of springs and wells, and of the chemical character of the waters with reference to their adaptability to domestic use and to irrigation. The chemical data were obtained (a) by field assays, which are approximately correct and probably of sufficient accuracy to be of value in

  16. Mandibular incisor apicoectomy in a Canadian Beaver.

    PubMed

    Steenkamp, Gerhard; Venter, Leon; Crossley, David; Buss, Peter

    2009-01-01

    A 52-month-old Canadian beaver was presented for treatment of lip trauma resulting from overgrowth of the right mandibular incisor tooth following earlier loss of the right maxillary incisor tooth. Extraction of the affected tooth was considered, but rejected due to the length of the embedded portion of rodent mandibular incisor teeth. The lip injury was managed by crown reduction (odontoplasty) of the overgrowing incisor tooth pending a more permanent treatment plan. A 2-cm apicoectomy of the right mandibular incisor tooth was performed to arrest growth of the tooth when the beaver was 82-months-old. The remainder of the tooth continued to erupt and was completely expelled during a 9-month period with one additional odontoplasty being required. The beaver continued to feed normally with just the left maxillary and mandibular incisor teeth until its death at 118-months, with odontoplasty performed twice on the remaining incisor teeth during the 30-months following exfoliation.

  17. Biology Today: Of Wishbones, Beavers & Blinking.

    ERIC Educational Resources Information Center

    Flannery, Maura, Ed.

    1989-01-01

    Provided is a discussion of items covering a variety of fascinating biological topics which include: the elasticity of the furcula of starlings in flight, beavers increasing the greenhouse effect, effective invaders, traveling birds, the cuckoo deception, competitive sperm, hearing springs, heat and sight, blinking as punctuation, mutations, and…

  18. Beavers-Timberlawn Family Evaluation Scale.

    ERIC Educational Resources Information Center

    Brock, Gregory W.

    1986-01-01

    Critiques the Beavers-Timberlawn Family Evaluation Scale (BT), a measure designed to be used in conjunction with other scales to more fully identify the health/competence of a family. Reviews the assessment tool's strengths and limitations. Finds the BT to be an important contribution to clinical work. (ABB)

  19. Biology Today: Of Wishbones, Beavers & Blinking.

    ERIC Educational Resources Information Center

    Flannery, Maura, Ed.

    1989-01-01

    Provided is a discussion of items covering a variety of fascinating biological topics which include: the elasticity of the furcula of starlings in flight, beavers increasing the greenhouse effect, effective invaders, traveling birds, the cuckoo deception, competitive sperm, hearing springs, heat and sight, blinking as punctuation, mutations, and…

  20. 72. VISITOR'S CENTER, MODEL OF BOILER CHAMBER, AUXILIARY CHAMBER, REACTOR ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    72. VISITOR'S CENTER, MODEL OF BOILER CHAMBER, AUXILIARY CHAMBER, REACTOR AND CANAL (LOCATION T) - Shippingport Atomic Power Station, On Ohio River, 25 miles Northwest of Pittsburgh, Shippingport, Beaver County, PA

  1. Competition favors elk over beaver in a riparian willow ecosystem

    USGS Publications Warehouse

    Baker, B.W.; Peinetti, H.R.; Coughenour, M.C.; Johnson, T.L.

    2012-01-01

    Beaver (Castor spp.) conservation requires an understanding of their complex interactions with competing herbivores. Simulation modeling offers a controlled environment to examine long-term dynamics in ecosystems driven by uncontrollable variables. We used a new version of the SAVANNA ecosystem model to investigate beaver (C. Canadensis) and elk (Cervus elapses) competition for willow (Salix spp.). We initialized the model with field data from Rocky Mountain National Park, Colorado, USA, to simulate a 4-ha riparian ecosystem containing beaver, elk, and willow. We found beaver persisted indefinitely when elk density was or = 30 elk km_2. The loss of tall willow preceded rapid beaver declines, thus willow condition may predict beaver population trajectory in natural environments. Beaver were able to persist with slightly higher elk densities if beaver alternated their use of foraging sites in a rest-rotation pattern rather than maintained continuous use. Thus, we found asymmetrical competition for willow strongly favored elk over beaver in a simulated montane ecosystem. Finally, we discuss application of the SAVANNA model and mechanisms of competition relative to beaver persistence as metapopulations, ecological resistance and alternative state models, and ecosystem regulation.

  2. Where and How Wolves (Canis lupus) Kill Beavers (Castor canadensis)

    PubMed Central

    Gable, Thomas D.; Windels, Steve K.; Bruggink, John G.; Homkes, Austin T.

    2016-01-01

    Beavers (Castor canadensis) can be a significant prey item for wolves (Canis lupus) in boreal ecosystems due to their abundance and vulnerability on land. How wolves hunt beavers in these systems is largely unknown, however, because observing predation is challenging. We inferred how wolves hunt beavers by identifying kill sites using clusters of locations from GPS-collared wolves in Voyageurs National Park, Minnesota. We identified 22 sites where wolves from 4 different packs killed beavers. We classified these kill sites into 8 categories based on the beaver-habitat type near which each kill occurred. Seasonal variation existed in types of kill sites as 7 of 12 (58%) kills in the spring occurred at sites below dams and on shorelines, and 8 of 10 (80%) kills in the fall occurred near feeding trails and canals. From these kill sites we deduced that the typical hunting strategy has 3 components: 1) waiting near areas of high beaver use (e.g., feeding trails) until a beaver comes near shore or ashore, 2) using vegetation, the dam, or other habitat features for concealment, and 3) immediately attacking the beaver, or ambushing the beaver by cutting off access to water. By identifying kill sites and inferring hunting behavior we have provided the most complete description available of how and where wolves hunt and kill beavers. PMID:27992441

  3. Where and How Wolves (Canis lupus) Kill Beavers (Castor canadensis).

    PubMed

    Gable, Thomas D; Windels, Steve K; Bruggink, John G; Homkes, Austin T

    2016-01-01

    Beavers (Castor canadensis) can be a significant prey item for wolves (Canis lupus) in boreal ecosystems due to their abundance and vulnerability on land. How wolves hunt beavers in these systems is largely unknown, however, because observing predation is challenging. We inferred how wolves hunt beavers by identifying kill sites using clusters of locations from GPS-collared wolves in Voyageurs National Park, Minnesota. We identified 22 sites where wolves from 4 different packs killed beavers. We classified these kill sites into 8 categories based on the beaver-habitat type near which each kill occurred. Seasonal variation existed in types of kill sites as 7 of 12 (58%) kills in the spring occurred at sites below dams and on shorelines, and 8 of 10 (80%) kills in the fall occurred near feeding trails and canals. From these kill sites we deduced that the typical hunting strategy has 3 components: 1) waiting near areas of high beaver use (e.g., feeding trails) until a beaver comes near shore or ashore, 2) using vegetation, the dam, or other habitat features for concealment, and 3) immediately attacking the beaver, or ambushing the beaver by cutting off access to water. By identifying kill sites and inferring hunting behavior we have provided the most complete description available of how and where wolves hunt and kill beavers.

  4. The geomorphic influences of beaver dams and failures of beaver dams

    NASA Astrophysics Data System (ADS)

    Butler, David R.; Malanson, George P.

    2005-10-01

    Uncounted millions of beaver ponds and dams existed in North America prior to European contact and colonization. These ponds acted as sediment traps that contained tens to hundreds of billions of cubic meters of sediment that would otherwise have passed through the fluvial system. Removal of beavers by overtrapping in the 16th-19th centuries severely reduced their number and the number of ponds and dams. Dam removal altered the fluvial landscape of North America, inducing sediment evacuation and entrenchment in concert with widespread reduction in the wetlands environments. Partial recovery of beaver populations in the 20th century has allowed reoccupation of the entirety of the pre-contact range, but at densities of only one-tenth the numbers. Nevertheless, modern beaver ponds also trap large volumes of sediment in the high hundred millions to low billions of cubic meters range. Failure of beaver dams is a more common phenomenon than often assumed in the literature. During the past 20 years, numerous cases of dam failure have been documented that resulted in outburst floods. These floods have been responsible for 13 deaths and numerous injuries, including significant impacts on railway lines.

  5. Rapid surface-water volume estimations in beaver ponds

    NASA Astrophysics Data System (ADS)

    Karran, Daniel J.; Westbrook, Cherie J.; Wheaton, Joseph M.; Johnston, Carol A.; Bedard-Haughn, Angela

    2017-02-01

    Beaver ponds are surface-water features that are transient through space and time. Such qualities complicate the inclusion of beaver ponds in local and regional water balances, and in hydrological models, as reliable estimates of surface-water storage are difficult to acquire without time- and labour-intensive topographic surveys. A simpler approach to overcome this challenge is needed, given the abundance of the beaver ponds in North America, Eurasia, and southern South America. We investigated whether simple morphometric characteristics derived from readily available aerial imagery or quickly measured field attributes of beaver ponds can be used to approximate surface-water storage among the range of environmental settings in which beaver ponds are found. Studied were a total of 40 beaver ponds from four different sites in North and South America. The simplified volume-area-depth (V-A-h) approach, originally developed for prairie potholes, was tested. With only two measurements of pond depth and corresponding surface area, this method estimated surface-water storage in beaver ponds within 5 % on average. Beaver pond morphometry was characterized by a median basin coefficient of 0.91, and dam length and pond surface area were strongly correlated with beaver pond storage capacity, regardless of geographic setting. These attributes provide a means for coarsely estimating surface-water storage capacity in beaver ponds. Overall, this research demonstrates that reliable estimates of surface-water storage in beaver ponds only requires simple measurements derived from aerial imagery and/or brief visits to the field. Future research efforts should be directed at incorporating these simple methods into both broader beaver-related tools and catchment-scale hydrological models.

  6. 78 FR 28780 - Proposed Flood Elevation Determinations for Beaver County, Pennsylvania (All Jurisdictions)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-16

    ... Beaver County, Pennsylvania (All Jurisdictions) AGENCY: Federal Emergency Management Agency, DHS. ACTION... proposed rule concerning proposed flood elevation determinations for Beaver County, Pennsylvania (All...

  7. Yersinia enterocolitica strains isolated from beavers (Castor fiber).

    PubMed

    Platt-Samoraj, A; Syczyło, K; Bancerz-Kisiel, A; Szczerba-Turek, A; Giżejewska, A; Szweda, W

    2015-01-01

    Pseudocloacal swabs and palatine tonsils from beavers have been examined for the Yersinia enterocolitica presence. Thirty-six samples from 24 beavers were collected and subjected to bacteriological examinations including sero- and biotypisation. Amplicons confirmed by PCR as Y. enterocolitica were sequenced. Positive samples originated from 4 out of the 24 beavers (16.7 %) and all the strains belonged to biotype 1A. The study suggested that Y. enterocolitica could be isolated from beavers, which may therefore be treated as a reservoir, a significant factor of water contamination and a vector of the Y. enterocolitica.

  8. REACTOR

    DOEpatents

    Szilard, L.

    1963-09-10

    A breeder reactor is described, including a mass of fissionable material that is less than critical with respect to unmoderated neutrons and greater than critical with respect to neutrons of average energies substantially greater than thermal, a coolant selected from sodium or sodium--potassium alloys, a control liquid selected from lead or lead--bismuth alloys, and means for varying the quantity of control liquid in the reactor. (AEC)

  9. REACTOR

    DOEpatents

    Christy, R.F.

    1961-07-25

    A means is described for co-relating the essential physical requirements of a fission chain reaction in order that practical, compact, and easily controllable reactors can be built. These objects are obtained by employing a composition of fissionsble isotope and moderator in fluid form in which the amount of fissionsble isotcpe present governs the reaction. The size of the reactor is no longer a critical factor, the new criterion being the concentration of the fissionable isotope.

  10. Alteration of stream temperature by natural and artificial beaver dams.

    PubMed

    Weber, Nicholas; Bouwes, Nicolaas; Pollock, Michael M; Volk, Carol; Wheaton, Joseph M; Wathen, Gus; Wirtz, Jacob; Jordan, Chris E

    2017-01-01

    Beaver are an integral component of hydrologic, geomorphic, and biotic processes within North American stream systems, and their propensity to build dams alters stream and riparian structure and function to the benefit of many aquatic and terrestrial species. Recognizing this, beaver relocation efforts and/or application of structures designed to mimic the function of beaver dams are increasingly being utilized as effective and cost-efficient stream and riparian restoration approaches. Despite these verities, the notion that beaver dams negatively impact stream habitat remains common, specifically the assumption that beaver dams increase stream temperatures during summer to the detriment of sensitive biota such as salmonids. In this study, we tracked beaver dam distributions and monitored water temperature throughout 34 km of stream for an eight-year period between 2007 and 2014. During this time the number of natural beaver dams within the study area increased by an order of magnitude, and an additional 4 km of stream were subject to a restoration manipulation that included installing a high-density of Beaver Dam Analog (BDA) structures designed to mimic the function of natural beaver dams. Our observations reveal several mechanisms by which beaver dam development may influence stream temperature regimes; including longitudinal buffering of diel summer temperature extrema at the reach scale due to increased surface water storage, and creation of cool-water channel scale temperature refugia through enhanced groundwater-surface water connectivity. Our results suggest that creation of natural and/or artificial beaver dams could be used to mitigate the impact of human induced thermal degradation that may threaten sensitive species.

  11. Alteration of stream temperature by natural and artificial beaver dams

    PubMed Central

    Bouwes, Nicolaas; Pollock, Michael M.; Volk, Carol; Wheaton, Joseph M.; Wathen, Gus; Wirtz, Jacob; Jordan, Chris E.

    2017-01-01

    Beaver are an integral component of hydrologic, geomorphic, and biotic processes within North American stream systems, and their propensity to build dams alters stream and riparian structure and function to the benefit of many aquatic and terrestrial species. Recognizing this, beaver relocation efforts and/or application of structures designed to mimic the function of beaver dams are increasingly being utilized as effective and cost-efficient stream and riparian restoration approaches. Despite these verities, the notion that beaver dams negatively impact stream habitat remains common, specifically the assumption that beaver dams increase stream temperatures during summer to the detriment of sensitive biota such as salmonids. In this study, we tracked beaver dam distributions and monitored water temperature throughout 34 km of stream for an eight-year period between 2007 and 2014. During this time the number of natural beaver dams within the study area increased by an order of magnitude, and an additional 4 km of stream were subject to a restoration manipulation that included installing a high-density of Beaver Dam Analog (BDA) structures designed to mimic the function of natural beaver dams. Our observations reveal several mechanisms by which beaver dam development may influence stream temperature regimes; including longitudinal buffering of diel summer temperature extrema at the reach scale due to increased surface water storage, and creation of cool—water channel scale temperature refugia through enhanced groundwater—surface water connectivity. Our results suggest that creation of natural and/or artificial beaver dams could be used to mitigate the impact of human induced thermal degradation that may threaten sensitive species. PMID:28520714

  12. REACTOR

    DOEpatents

    Roman, W.G.

    1961-06-27

    A pressurized water reactor in which automatic control is achieved by varying the average density of the liquid moderator-cooiant is patented. Density is controlled by the temperature and power level of the reactor ftself. This control can be effected by the use of either plate, pellet, or tubular fuel elements. The fuel elements are disposed between upper and lower coolant plenum chambers and are designed to permit unrestricted coolant flow. The control chamber has an inlet opening communicating with the lower coolant plenum chamber and a restricted vapor vent communicating with the upper coolant plenum chamber. Thus, a variation in temperature of the fuel elements will cause a variation in the average moderator density in the chamber which directly affects the power level of the reactor.

  13. REACTORS

    DOEpatents

    Spitzer, L. Jr.

    1961-10-01

    Thermonuclear reactors, methods, and apparatus are described for controlling and confining high temperature plasma. Main axial confining coils in combination with helical windings provide a rotational transform that avoids the necessity of a figure-eight shaped reactor tube. The helical windings provide a multipolar helical magnetic field transverse to the axis of the main axial confining coils so as to improve the effectiveness of the confining field by counteracting the tendency of the more central lines of force in the stellarator tube to exchange positions with the magnetic lines of force nearer the walls of the tube. (AEC)

  14. 33 CFR 117.705 - Beaver Dam Creek.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Beaver Dam Creek. 117.705 Section 117.705 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements New Jersey § 117.705 Beaver Dam Creek. The draw of...

  15. 33 CFR 117.705 - Beaver Dam Creek.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Beaver Dam Creek. 117.705 Section 117.705 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements New Jersey § 117.705 Beaver Dam Creek. The draw of...

  16. 33 CFR 117.705 - Beaver Dam Creek.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Beaver Dam Creek. 117.705 Section 117.705 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements New Jersey § 117.705 Beaver Dam Creek. The draw of...

  17. 33 CFR 117.705 - Beaver Dam Creek.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Beaver Dam Creek. 117.705 Section 117.705 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements New Jersey § 117.705 Beaver Dam Creek. The draw of...

  18. 33 CFR 117.705 - Beaver Dam Creek.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Beaver Dam Creek. 117.705 Section 117.705 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements New Jersey § 117.705 Beaver Dam Creek. The draw of...

  19. Geotagging Digital Collections: BeaverTracks Mobile Project

    ERIC Educational Resources Information Center

    Griggs, Kim

    2011-01-01

    BeaverTracks Historical Locations and Walking Tour is a mobile project at Oregon State University (OSU), where the author serves as programmer/analyst. It connects the past to the present by linking historic images to current campus locations. The goal of BeaverTracks is to showcase and bring attention to OSU Libraries' digital collections as well…

  20. Geotagging Digital Collections: BeaverTracks Mobile Project

    ERIC Educational Resources Information Center

    Griggs, Kim

    2011-01-01

    BeaverTracks Historical Locations and Walking Tour is a mobile project at Oregon State University (OSU), where the author serves as programmer/analyst. It connects the past to the present by linking historic images to current campus locations. The goal of BeaverTracks is to showcase and bring attention to OSU Libraries' digital collections as well…

  1. Hydraulic characteristics and dynamics of beaver dams in a Midwestern U.S. agricultural waershed

    Treesearch

    M.C. McCullough; D.E. Eisenhauer; M.G. Dosskey; D.M. Admiraal

    2006-01-01

    Populations of Noth America beaver (castor canadensis) have increased in the past decades throughout the Midwestern U.S., leading to an increase in the frequency of beaver dams in small streams. Beaver dams form ponds and slow water velocity. Multiple dams create a stair-step effect on the water surface profile. The hydraulic and geomorphic influence of beaver dams on...

  2. Modeling a beaver population on the Prescott Peninsula, Massachusetts: Feasibility of LANDSAT as an input

    NASA Technical Reports Server (NTRS)

    Finn, J. T.; Howard, R.

    1981-01-01

    A preliminary dynamic model of beaver spatial distribution and population growth was developed. The feasibility of locating beaver ponds on LANDSAT digital tapes, and of using this information to provide initial conditions of beaver spatial distribution for the model, and to validate model predictions is discussed. The techniques used to identify beaver ponds on LANDSAT are described.

  3. 103. PWR2 CORE SUPPORT FLANGE BEING SEATED ON REACTOR VESSEL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    103. PWR-2 CORE SUPPORT FLANGE BEING SEATED ON REACTOR VESSEL FLANGE, APRIL 14, 1964 - Shippingport Atomic Power Station, On Ohio River, 25 miles Northwest of Pittsburgh, Shippingport, Beaver County, PA

  4. Quantifying the multiple, environmental benefits of reintroducing the Eurasian Beaver

    NASA Astrophysics Data System (ADS)

    Brazier, Richard; Puttock, Alan; Graham, Hugh; Anderson, Karen; Cunliffe, Andrew; Elliott, Mark

    2016-04-01

    Beavers are ecological engineers with an ability to modify the structure and flow of fluvial systems and create complex wetland environments with dams, ponds and canals. Consequently, beaver activity has potential for river restoration, management and the provision of multiple environmental ecosystem services including biodiversity, flood risk mitigation, water quality and sustainable drinking water provision. With the current debate surrounding the reintroduction of beavers into the United Kingdom, it is critical to monitor the impact of beavers upon the environment. We have developed and implemented a monitoring strategy to quantify the impact of reintroducing the Eurasian Beaver on multiple environmental ecosystem services and river systems at a range of scales. First, the experimental design and preliminary results will be presented from the Mid-Devon Beaver Trial, where a family of beavers has been introduced to a 3 ha enclosure situated upon a first order tributary of the River Tamar. The site was instrumented to monitor the flow rate and quality of water entering and leaving the site. Additionally, the impacts of beavers upon riparian vegetation structure, water/carbon storage were investigated. Preliminary results indicate that beaver activity, particularly the building of ponds and dams, increases water storage within the landscape and moderates the river response to rainfall. Baseflow is enhanced during dry periods and storm flow is attenuated, potentially reducing the risk of flooding downstream. Initial analysis of water quality indicates that water entering the site (running off intensively managed grasslands upslope), has higher suspended sediment loads and nitrate levels, than that leaving the site, after moving through the series of beaver ponds. These results suggest beaver activity may also act as a means by which the negative impact of diffuse water pollution from agriculture can be mitigated thus providing cleaner water in rivers downstream

  5. The Genetic Legacy of Multiple Beaver Reintroductions in Central Europe

    PubMed Central

    Frosch, Christiane; Kraus, Robert H. S.; Angst, Christof; Allgöwer, Rainer; Michaux, Johan; Teubner, Jana; Nowak, Carsten

    2014-01-01

    The comeback of the Eurasian beaver (Castor fiber) throughout western and central Europe is considered a major conservation success. Traditionally, several subspecies are recognised by morphology and mitochondrial haplotype, each linked to a relict population. During various reintroduction programs in the 20th century, beavers from multiple source localities were released and now form viable populations. These programs differed in their reintroduction strategies, i.e., using pure subspecies vs. mixed source populations. This inhomogeneity in management actions generated ongoing debates regarding the origin of present beaver populations and appropriate management plans for the future. By sequencing of the mitochondrial control region and microsatellite genotyping of 235 beaver individuals from five selected regions in Germany, Switzerland, Luxembourg, and Belgium we show that beavers from at least four source origins currently form admixed, genetically diverse populations that spread across the study region. While regional occurrences of invasive North American beavers (n = 20) were found, all but one C. fiber bore the mitochondrial haplotype of the autochthonous western Evolutionary Significant Unit (ESU). Considering this, as well as the viability of admixed populations and the fact that the fusion of different lineages is already progressing in all studied regions, we argue that admixture between different beaver source populations should be generally accepted. PMID:24827835

  6. Reactor

    DOEpatents

    Evans, Robert M.

    1976-10-05

    1. A neutronic reactor having a moderator, coolant tubes traversing the moderator from an inlet end to an outlet end, bodies of material fissionable by neutrons of thermal energy disposed within the coolant tubes, and means for circulating water through said coolant tubes characterized by the improved construction wherein the coolant tubes are constructed of aluminum having an outer diameter of 1.729 inches and a wall thickness of 0.059 inch, and the means for circulating a liquid coolant through the tubes includes a source of water at a pressure of approximately 350 pounds per square inch connected to the inlet end of the tubes, and said construction including a pressure reducing orifice disposed at the inlet ends of the tubes reducing the pressure of the water by approximately 150 pounds per square inch.

  7. The Beaver's Phylogenetic Lineage Illuminated by Retroposon Reads.

    PubMed

    Doronina, Liliya; Matzke, Andreas; Churakov, Gennady; Stoll, Monika; Huge, Andreas; Schmitz, Jürgen

    2017-03-03

    Solving problematic phylogenetic relationships often requires high quality genome data. However, for many organisms such data are still not available. Among rodents, the phylogenetic position of the beaver has always attracted special interest. The arrangement of the beaver's masseter (jaw-closer) muscle once suggested a strong affinity to some sciurid rodents (e.g., squirrels), placing them in the Sciuromorpha suborder. Modern molecular data, however, suggested a closer relationship of beaver to the representatives of the mouse-related clade, but significant data from virtually homoplasy-free markers (for example retroposon insertions) for the exact position of the beaver have not been available. We derived a gross genome assembly from deposited genomic Illumina paired-end reads and extracted thousands of potential phylogenetically informative retroposon markers using the new bioinformatics coordinate extractor fastCOEX, enabling us to evaluate different hypotheses for the phylogenetic position of the beaver. Comparative results provided significant support for a clear relationship between beavers (Castoridae) and kangaroo rat-related species (Geomyoidea) (p < 0.0015, six markers, no conflicting data) within a significantly supported mouse-related clade (including Myodonta, Anomaluromorpha, and Castorimorpha) (p < 0.0015, six markers, no conflicting data).

  8. Holocene beaver damming, fluvial geomorphology, and climate in Yellowstone National Park, Wyoming

    NASA Astrophysics Data System (ADS)

    Persico, Lyman; Meyer, Grant

    2009-05-01

    We use beaver-pond deposits and geomorphic characteristics of small streams to assess long-term effects of beavers and climate change on Holocene fluvial activity in northern Yellowstone National Park. Although beaver damming has been considered a viable mechanism for major aggradation of mountain stream valleys, this has not been previously tested with stratigraphic and geochronologic data. Thirty-nine radiocarbon ages on beaver-pond deposits fall primarily within the last 4000 yr, but gaps in dated beaver occupation from ~ 2200-1800 and 950-750 cal yr BP correspond with severe droughts that likely caused low to ephemeral discharges in smaller streams, as in modern severe drought. Maximum channel gradient for reaches with Holocene beaver-pond deposits decreases with increasing basin area, implying that stream power limits beaver damming and pond sediment preservation. In northern Yellowstone, the patchy distribution and cumulative thickness of mostly < 2 m of beaver-pond deposits indicate that net aggradation forced by beaver damming is small, but beaver-enhanced aggradation in some glacial scour depressions is greater. Although 20th-century beaver loss and dam abandonment caused significant local channel incision, most downcutting along alluvial reaches of the study streams is unrelated to beaver dam abandonment or predates historic beaver extirpation.

  9. Beavers as Agents of Biogeomorphic Change: A Review and Suggestions for Teaching Exercises.

    ERIC Educational Resources Information Center

    Butler, David R.

    1991-01-01

    Discusses beavers and their geomorphic impacts on their environment. Considers dam building, bank burrowing, and canal building. Suggests using the beaver as a classroom and field trip example to illustrate animals' effects on the physical landscape. Provides a review of published works on beavers in their roles as geomorphic agents. (DK)

  10. Beavers as Agents of Biogeomorphic Change: A Review and Suggestions for Teaching Exercises.

    ERIC Educational Resources Information Center

    Butler, David R.

    1991-01-01

    Discusses beavers and their geomorphic impacts on their environment. Considers dam building, bank burrowing, and canal building. Suggests using the beaver as a classroom and field trip example to illustrate animals' effects on the physical landscape. Provides a review of published works on beavers in their roles as geomorphic agents. (DK)

  11. The Beaver: A Marine Education Infusion Unit. Northern New England Marine Education Project.

    ERIC Educational Resources Information Center

    Maine Univ., Orono. Coll. of Education.

    This interdisciplinary unit is intended for use with third grade classes. It examines the history and economics of man's relationships to the beaver. It investigates the natural history of the beaver, its anatomy, range, food sources, and the skills it employs to modify its environment by building dams. The structure of beaver dams is examined.…

  12. Habitat and conservation status of the beaver in the Sierra San Luis Sonora, Mexico

    Treesearch

    Karla Pelz Serrano; Eduardo Ponce Guevara; Carlos A. Lopez Gonzalez

    2005-01-01

    The status of beaver (Castor canadensis) in northeastern Sonora, Mexico, is uncertain. We surveyed the Cajon Bonito River to assess the beaver’s status and habitat and found five colonies. Limiting factors appear to be pollution due to animal waste, deforestation of riparian trees, and human exploitation. Beavers did not appear to require habitat...

  13. A Review of Techniques for Minimizing Beaver and White-Tailed Deer Damage in Southern Hardwoods

    Treesearch

    Edward P. Hill; Douglas N. Lasher; R. Blake. Roper

    1978-01-01

    Methods of reducing beaver and deer damage to hardwood forest resources are reviewed. Beaver controls considered were poisons, chemosterilants, predators, and trapping. Population reduction through trapping with 330 conibear traps for two weeks during two successive years effectively eliminates beaver from small watersheds and shows greater promise for control than...

  14. Beaver colony density trends on the Chequamegon-Nicolet National Forest, 1987-2013

    Treesearch

    Christine A. Ribic; Deahn M. Donner; Albert J. Beck; David J. Rugg; Sue Reinecke; Dan Eklund; Christopher A. Lepczyk

    2017-01-01

    The North American beaver (Castor canadensis) is a managed species in the United States. In northern Wisconsin, as part of the state-wide beaver management program, the Chequamegon-Nicolet National Forest removes beavers from targeted trout streams on U.S. Forest Service lands. However, the success of this management program has not been evaluated...

  15. Woody plants selected by beavers in the Appalacian Ridge and Valley Province

    Treesearch

    Hewlette S. Crawford; R. G. Hooper; R. F. Harlow

    1976-01-01

    The availability of woody plants and the selection of plants by beavers along mountain streams was studied in four areas of the Appalachian Ridge and Valley Province in Virginia. Beavers' choice of woody plants varied between areas. Many species of woody plants were cut by beavers. They climbed slopes with gradients up to 80 percent to cut trees. Large as well as...

  16. Energy requirements of beavers (Castor canadensis) swimming underwater.

    PubMed

    Allers, D; Culik, B M

    1997-01-01

    Energy requirements of beavers (Castor canadensis) swimming voluntarily underwater were investigated in Neumünster Zoo (Germany) in a covered, still-water swim channel with oxygen and carbon dioxide respirometry. During the experiments, all activities of the beavers were monitored and recorded. While at rest within their thermoneutral zone on land (17 degrees C), beavers had a respiratory quotient of 0.95 and a resting metabolic rate of 1.58 W kg-1. When resting in water, energy requirements rose to 2.31 W kg-1. When swimming underwater in the channel, beavers preferred a mean speed of 0.64 m s-1, and their energy requirements rose to 2.64 W kg-1. Cost of transport, however, was minimal at 0.9 m s-1 and amounted to 0.36 J N-1 m-1. Although beavers must compromise form and function to operate on water and on land, their energy requirements while diving amount to only 1.65 times the resting metabolic rate and compare well with those of accomplished swimmers such as aquatic mammals and birds.

  17. Red maple (Acer rubrum) inhibits feeding by beaver (Castor canadensis).

    PubMed

    Müller-Schwarze, D; Schulte, B A; Sun, L; Müller-Schwarze, A; Müller-Schwarze, C

    1994-08-01

    At many beaver (Castor canadensis) sites at Allegany State Park in New York State, red maple (Acer rubrum) is the only or one of the few tree species left standing at the ponds' edges. The relative palatability of red maple (RM) was studied in three ways. (1) At seven beaver sites, the available and utilized trees were recorded and an electivity index (E) computed. Of 15 tree species, RM ranked second or fourth lowest. (2) In experiment I, RM, sugar maple (A. saccharum, SM), and quaking aspen (Populus tremuloides) logs were presented cafeteria style at 10 colonies. RM was the least preferred. (3) Bark of RM was extracted with solvents. Aspen logs were painted (experiment II) or soaked (experiment III) with this RM extract and presented to beaver cafeteria-style, along with aspen and RM controls. This treatment rendered aspen logs less palatable, indicating that a chemical factor had been transferred.

  18. Yersinia pseudotuberculosis septicemia in a beaver from Washington State.

    PubMed

    Gaydos, Joseph K; Zabek, Erin; Raverty, Stephen

    2009-10-01

    An emaciated, free-ranging, sub-adult, male beaver (Castor canadensis) was found dead and was necropsied. Microscopically, the beaver had acute necrotizing hepatitis and splenitis with florid lobulated colonies of extracellular coccobacilli. Intravascular septic emboli were identified in lung, small intestine, and kidney, and discrete ulcers with scattered superficial extracellular accumulation of coccobacilli were noted on tail margins and plantar surfaces of the hind feet. Yersinia pseudotuberculosis was cultured on Columbia blood and MacConkey agar and identified by API 20E. Based on the pathology and acute mortality described in this case, as well as historical reports of Y. pseudotuberculosis related mortality in other beavers, this species could serve as a public health sentinel for localized occurrences of this bacterium.

  19. A subsurface model of the beaver meadow complex

    NASA Astrophysics Data System (ADS)

    Nash, C.; Grant, G.; Flinchum, B. A.; Lancaster, J.; Holbrook, W. S.; Davis, L. G.; Lewis, S.

    2015-12-01

    Wet meadows are a vital component of arid and semi-arid environments. These valley spanning, seasonally inundated wetlands provide critical habitat and refugia for wildlife, and may potentially mediate catchment-scale hydrology in otherwise "water challenged" landscapes. In the last 150 years, these meadows have begun incising rapidly, causing the wetlands to drain and much of the ecological benefit to be lost. The mechanisms driving this incision are poorly understood, with proposed means ranging from cattle grazing to climate change, to the removal of beaver. There is considerable interest in identifying cost-effective strategies to restore the hydrologic and ecological conditions of these meadows at a meaningful scale, but effective process based restoration first requires a thorough understanding of the constructional history of these ubiquitous features. There is emerging evidence to suggest that the North American beaver may have had a considerable role in shaping this landscape through the building of dams. This "beaver meadow complex hypothesis" posits that as beaver dams filled with fine-grained sediments, they became large wet meadows on which new dams, and new complexes, were formed, thereby aggrading valley bottoms. A pioneering study done in Yellowstone indicated that 32-50% of the alluvial sediment was deposited in ponded environments. The observed aggradation rates were highly heterogeneous, suggesting spatial variability in the depositional process - all consistent with the beaver meadow complex hypothesis (Polvi and Wohl, 2012). To expand on this initial work, we have probed deeper into these meadow complexes using a combination of geophysical techniques, coring methods and numerical modeling to create a 3-dimensional representation of the subsurface environments. This imaging has given us a unique view into the patterns and processes responsible for the landforms, and may shed further light on the role of beaver in shaping these landscapes.

  20. RESEARCH: Attitudes of Private- and Public-Land Managers in Wyoming, USA, Toward Beaver.

    PubMed

    McKINSTRY; ANDERSON

    1999-01-01

    / A mail survey concerning beaver (Castor canadensis) management in Wyoming, USA, was sent to 5265 private-land managers and 124 public-land managers during 1993. The survey was developed in response to increasing interest in beaver management and beaver reintroduction possibilities. Private-land managers responding to the survey supplied information on 62,859 km2 of land area and 20,037 km of streams. Primary concerns about beaver damage centered on (in decreasing order of importance) blocked irrigation ditches, girdled timber, blocked culverts, and flooded pastures, roads, crops, and timber. Primary benefits that landowners perceive that beaver give them were, in order of importance, elevated water tables, increased riparian vegetation, and increased stock-watering opportunities. Public-land managers also listed these benefits and detriments among their top concerns for beaver. Over 45% of landowners with beaver on their property and all of the public-land managers displayed an interest in a beaver reintroduction program and in more proactive beaver management. KEY WORDS: Beaver; Beaver management; Castor canadensis; Landowners; Mail surveys; Wildlife values; Wildlife damage

  1. Mites of the genus Schizocarpus Trouessart, 1896 (Acariformes: Chirodiscidae) from the North American beavers (Castor canadensis) in Russia.

    PubMed

    Bochkov, A V; Saveljev, A P

    2014-01-01

    Four native species of parasitic mites belonging to the genus Schizocarpus Trouessart, 1896 (Acariformes: Chirodiscidae) are recorded on the North American beaver Castor canadensis Kuhl, 1820 (Rodentia: Castoridae) from Russia. Totally ten beavers from all three main geographically isolated populations of in Russia (Leningrad Province, Voronezh Biosphere Reserve (beaver farm) and Khabarovsk Territory) were examined. Additionally, in captivity (Voronezh beaver farm) eight species were recorded switched from the Eurasian beaver Castor fiber Linnaeus, 1758 on C. canadensis.

  2. Do beavers promote the invasion of non-native Tamarix in the Grand Canyon riparian zone

    USGS Publications Warehouse

    Mortenson, S.G.; Weisberg, P.J.; Ralston, B.E.

    2008-01-01

    Beavers (Castor canadensis Kuhl) can influence the competitive dynamics of plant species through selective foraging, collection of materials for dam creation, and alteration of hydrologic conditions. In the Grand Canyon National Park, the native Salix gooddingii C.R.Ball (Goodding's willow) and Salix exigua Nutt. (coyote willow) are a staple food of beavers. Because Salix competes with the invasive Tamarix ramosissima Ledeb., land mangers are concerned that beavers may cause an increase in Tamarix through selective foraging of Salix. A spatial analysis was conducted to assess whether the presence of beavers correlates with the relative abundance of Salix and Tamarix. These methods were designed to detect a system-wide effect of selective beaver foraging in this large study area (367 linear km of riparian habitat). Beavers, Salix, and Tamarix co-occurred at the broadest scales because they occupied similar riparian habitat, particularly geomorphic reaches of low and moderate resistivity. Once the affinity of Salix for particular reach types was accounted for, the presence of Salix was independent of beaver distribution. However, there was a weak positive association between beaver presence and Salix cover. Salix was limited to geomorphic settings with greater sinuosity and distinct terraces, while Tamarix occurred in sinuous and straighter sections of river channel (cliffs, channel margins) where it dominated the woody species composition. After accounting for covariates representing river geomorphology, the proportion of riparian surfaces covered by Tamarix was significantly greater for sites where beavers were present. This indicates that either Tamarix and beavers co-occur in similar habitats, beavers prefer habitats that have high Tamarix cover, or beavers contribute to Tamarix dominance through selective use of its native woody competitors. The hypothesis that beaver herbivory contributes to Tamarix dominance should be considered further through more

  3. Responses of beaver (Castor canadensis Kuhl) to predator chemicals.

    PubMed

    Engelhart, A; Müller-Schwarze, D

    1995-09-01

    Free-ranging beaver (Castor canadensis) in two different beaver populations in New York State were exposed to predator chemicals to test feeding inhibition. Solvent extracts of feces were applied to stem sections of aspen, the preferred food tree of beavers, permitting smelling and tasting the samples. Predator odors were from wolf (Canis lupus), coyote (Canis latrans), dog (Canis familiaris), black bear (Ursus americanus), river otter (Lutra canadensis), lynx (Lynx canadensis), and African lion (Panthera leo). The experiment was repeated. The predator odors reduced feeding compared to untreated or solvent-treated controls. One population consumed 17.0% of the samples with predator odor and 27.0% of the controls in summer, and 48.4% and 60.0%, respectively, in autumn. The other population accepted 3.15% of the predator odor samples and 11.05% of the controls in summer. Coyote, lynx, and river otter odors had the strongest effects. Diesel oil and bitter-tasting neem extract had weaker effects. Predator odors are promising as feeding repellents for beaver.

  4. Changes in local mosquito fauna following beaver (Castor canadensis) activity.

    PubMed

    Butts, W L

    1986-09-01

    A marked decrease in anthropophilic temporary water mosquito populations subsequent to impoundment of extensive areas of larval development by beavers is documented. Absence to date of development of other mosquito species in the permanent water thus established is noted and discussed relative to current characteristics of the site.

  5. Signs in Speare's "The Sign of the Beaver."

    ERIC Educational Resources Information Center

    Moseley, Ann

    1995-01-01

    Describes the use of signs in Elizabeth George Speare's "The Sign of the Beaver," in which a settler youth and a young Indian learn to communicate by signs, and how the signs reveal much about each character's culture. Summarizes the plot elements of the book, including characters who are not as sympathetic to the Indian point of view.…

  6. A rare Uroglena bloom in Beaver Lake, Arkansas, spring 2015

    USGS Publications Warehouse

    Green, William R.; Hufhines, Brad

    2017-01-01

    A combination of factors triggered a Uroglena volvox bloom and taste and odor event in Beaver Lake, a water-supply reservoir in northwest Arkansas, in late April 2015. Factors contributing to the bloom included increased rainfall and runoff containing increased concentrations of dissolved organic carbon, followed by a stable pool, low nutrient concentrations, and an expansion of lake surface area and littoral zone. This was the first time U. volvox was identified in Beaver Lake and the first time it was recognized as a source of taste and odor. Routine water quality samples happened to be collected by the US Geological Survey and the Beaver Water District throughout the reservoir during the bloom—. Higher than normal rainfall in March 2015 increased the pool elevation in Beaver Lake by 2.3 m (by early April), increased the surface area by 10%, and increased the littoral zone by 1214 ha; these conditions persisted for 38 days, resulting from flood water being retained behind the dam. Monitoring programs that cover a wide range of reservoir features, including dissolved organic carbon, zooplankton, and phytoplankton, are valuable in explaining unusual events such as this Uroglena bloom.

  7. Normal ocular features, conjunctival microflora and intraocular pressure in the Canadian beaver (Castor canadensis).

    PubMed

    Cullen, C L

    2003-12-01

    The aim of the study was to assess the ocular features, normal conjunctival bacterial and fungal flora, and intraocular pressure (IOP) in the Canadian beaver (Castor canadensis). Sixteen, apparently healthy beavers with no evidence of ocular disease, and live-trapped in regions throughout Prince Edward Island. The beavers were sedated with intramuscular ketamine (12-15 mg/kg). Two culture specimens were obtained from the ventral conjunctival sac of both eyes of 10/16 beavers for aerobic and anaerobic bacterial and fungal identifications. The anterior ocular structures of all beavers were evaluated using a transilluminator and slit lamp biomicroscope. Palpebral fissure length (11/16 beavers), and horizontal and vertical corneal diameters (10/16 beavers) were measured. IOPs were measured in both eyes of 11/16 beavers using applanation tonometry. Both eyes of 3/16 beavers and one eye of 1/16 beavers were dilated using topical tropicamide prior to sedation to effect timely maximal dilation. Culture specimens and IOPs were not evaluated in these four animals. Indirect ophthalmoscopy was performed on 7/8 eyes of these four beavers. Conjunctival specimens from all eyes cultured positively for one or more isolates of aerobic bacteria. The most common isolate was Micrococcus spp. (five beavers; 9/20 eyes). Other isolates included a Gram-positive coccobacilli-like organism (four beavers; 7/20 eyes), Aeromonas hydrophila (three beavers; 4/20 eyes), Staphylococcus spp. (three beavers; 4/20 eyes), Gram positive bacilli (one beaver; 2/20 eyes), Enterobacter spp. (two beavers; 2/20 eyes), Streptococcus spp. (two beavers; 2/20 eyes), aerobic diphtheroids (one beaver; 1/20 eyes), and Pseudomonas spp. (one beaver; 1/20 eyes). Clostridium sordellii (one beaver; 1/20 eyes) and Peptostreptococcus spp. (one beaver; 1/20 eyes) were the sole anaerobic bacteria isolated. All conjunctival specimens were negative for growth of fungi. Ophthalmic examinations revealed the normal beaver eye and

  8. Colonial Era Impoundment of the Northeastern United States: Beaver Trapping and Low- head Dam Construction

    NASA Astrophysics Data System (ADS)

    Salant, N.; Bain, D.; Brandt, S.

    2008-12-01

    Hydrologic systems of the northeastern United States were transformed by European settler activities. The colonial economy shifted engineered water structures from beaver dams to human dams built for power generation. While the geomorphic effects of human-constructed dams have recently garnered considerable attention, few studies have investigated how intensive trapping for the fur trade, the near extermination of the Northeast beaver population, and the consequent loss of beaver ponds altered the regional water balance. Although reconstructions of colonial beaver populations have been made, none link the decline in beavers to its hydrologic impact. Beaver population models based on pre-colonial population estimates, historic harvest rates, and current-day population dynamics were used to simulate the corresponding decrease in pond numbers over time. Beaver populations declined dramatically during the seventeenth century, with harvest rates estimated at 2,000-10,000 beavers per year, resulting in expatriation in some sub-regions by the early 1700s. Using contemporary estimates of beaver pond volumes, the calculated loss in pond storage between 1600 and 1840 was approximately 17 million cubic meters of water and sediment, considerably larger than estimated storage gains from dam construction in the same period, suggesting that beaver eradication was a major driver of hydrologic change during the colonial era.

  9. Impact of Beaver Pond Colonization History on Methylmercury Concentrations in Surface Water.

    PubMed

    Levanoni, Oded; Bishop, Kevin; Mckie, Brendan G; Hartman, Göran; Eklöf, Karin; Ecke, Frauke

    2015-11-03

    Elevated concentrations of methylmercury (MeHg) in freshwater ecosystems are of major environmental concern in large parts of the northern hemisphere. Beaver ponds have been identified as a potentially important source of MeHg. The role of beavers might be especially pronounced in large parts of Europe, where beaver populations have expanded rapidly following near-extirpation. This study evaluates the role of the age and colonization history (encompassing patterns of use and reuse) of ponds constructed by the Eurasian beaver Castor fiber in regulating MeHg concentrations in Swedish streams. In 12 beaver systems located in three regions, we quantified MeHg concentrations together with other relevant parameters on five occasions per year in 2012-2013. Five were pioneer systems, inundated for the first time since beaver extirpation, and seven were recolonized, with dams reconstructed by newly recolonizing beavers. MeHg concentrations in pioneer but not in recolonized beaver systems were up to 3.5 fold higher downstream than upstream of the ponds, and varied between seasons and years. Our results show that pioneer inundation by beavers can increase MeHg concentrations in streams, but that this effect is negligible when dams are reconstructed on previously used ponds. We therefore expect that the recovery and expansion of beavers in the boreal system will only have a transitional effect on MeHg in the environment.

  10. Impacts of beaver dams on hydrologic and temperature regimes in a mountain stream

    NASA Astrophysics Data System (ADS)

    Majerova, M.; Neilson, B. T.; Schmadel, N. M.; Wheaton, J. M.; Snow, C. J.

    2015-01-01

    Beaver dams affect hydrologic processes, channel complexity, and stream temperature by increasing inundated areas and influencing groundwater-surface water interactions. We explored the impacts of beaver dams on hydrologic and temperature regimes at different spatial and temporal scales within a mountain stream in northern Utah over a three-year period spanning pre- and post-beaver colonization. Using continuous stream discharge, stream temperature, synoptic tracer experiments, and groundwater elevation measurements we documented pre-beaver conditions in the first year of the study. In the second year, we captured the initial effects of three beaver dams, while the third year included the effects of ten dams. After beaver colonization, reach scale discharge observations showed a shift from slightly losing to gaining. However, at the smaller sub-reach scale, the discharge gains and losses increased in variability due to more complex flow pathways with beaver dams forcing overland flow and increasing surface and subsurface storage. At the reach scale, temperatures were found to increase by 0.38 °C (3.8%), which in part is explained by a 230% increase in mean reach residence time. At the smallest, beaver dam scale, there were notable increases in the thermal heterogeneity where warmer and cooler niches were created. Through the quantification of hydrologic and thermal changes at different spatial and temporal scales, we document increased variability during post-beaver colonization and highlight the need to understand the impacts of beaver dams on stream ecosystems and their potential role in stream restoration.

  11. Agreement Between Community College of Beaver County and Community College of Beaver County Society of the Faculty (PSEA/NEA). September 1, 1972 to August 31, 1974.

    ERIC Educational Resources Information Center

    Beaver County Community Coll., Monaca, PA.

    This document contains the agreement between the Community College of Beaver County and the Community College of Beaver County Society of the Faculty for the period from September 1, 1972 through August 31, 1974. Contained in the articles of the agreement are sections covering academic freedom, grievance procedures, rights of faculty, use of…

  12. Prevalence of Microsporidia, Cryptosporidium spp., and Giardia spp. in beavers (Castor canadensis) in Massachusetts.

    PubMed

    Fayer, Ronald; Santín, Mónica; Trout, James M; DeStefano, Stephen; Koenen, Kiana; Kaur, Taranjit

    2006-12-01

    Feces from 62 beavers (Castor canadensis) in Massachusetts were examined by fluorescence microscopy (IFA) and polymerase chain reaction (PCR) for Microsporidia species, Cryptosporidium spp., and Giardia spp. between January 2002 and December 2004. PCR-positive specimens were further examined by gene sequencing. Protist parasites were detected in 6.4% of the beavers. All were subadults and kits. Microsporidia species were not detected. Giardia spp. was detected by IFA from four beavers; Cryptosporidium spp. was also detected by IFA from two of these beavers. However, gene sequence data for the ssrRNA gene from these two Cryptosporidium spp.-positive beavers were inconclusive in identifying the species. Nucleotide sequences of the TPI, ssrRNA, and beta-giardin genes for Giardia spp. (deposited in GenBank) indicated that the four beavers were excreting Giardia duodenalis Assemblage B, the zoonotic genotype representing a potential source of waterborne Giardia spp. cysts.

  13. BAYLISASCARIS PROCYONIS LARVA MIGRANS IN TWO CAPTIVE NORTH AMERICAN BEAVERS (CASTOR CANADENSIS).

    PubMed

    Desprez, Isabelle; Yabsley, Michael J; Fogelson, Susan B; Hicks, Jill A; Barber, Renee; Sladakovic, Izidora; Secrest, Scott A; Divers, Stephen J; Mayer, Jörg

    2017-03-01

    Baylisascaris procyonis larva migrans was diagnosed in two North American beavers ( Castor canadensis ) belonging to a zoological park in Clarke County, Georgia. Both beavers presented with neurological signs. One beaver died naturally and despite attempted treatment, the other beaver was euthanatized because of severe clinical signs and poor prognosis. Histologic evaluation of the beavers revealed evidence of parasitic migration characterized by several lesions, including eosinophilic granulomas in various organs, as well as necrotizing eosinophilic and lymphoplasmacytic to granulomatous polioencephalitis, leukoencephalitis and cervical leukomyelitis. This represents the first confirmed case of B. procyonis larva migrans in beaver and the first non-raccoon ( Procyon lotor ) host in the southeastern United States. This report highlights the need for clinicians and diagnosticians to consider baylisascariasis in animals with compatible clinical signs. Preventative measures should be considered for captive animals, because early diagnosis of B. procyonis is challenging, and treatment is often unrewarding.

  14. Prevalence of Microsporidia, Cryptosporidium spp., and Giardia spp. in beavers (Castor canadensis) in Massachusetts

    USGS Publications Warehouse

    Fayer, R.; Santin, M.; Trout, J.M.; DeStefano, S.; Koenen, K.; Kaur, T.

    2006-01-01

    Feces from 62 beavers (Castor canadensis) in Massachusetts were examined by fluorescence microscopy (IFA) and polymerase chain reaction (PCR) for Microsporidia species, Cryptosporidium spp., and Giardia spp. between January 2002 and December 2004. PCR-positive specimens were further examined by gene sequencing. Protist parasites were detected in 6.4% of the beavers. All were subadults and kits. Microsporidia species were not detected. Giardia spp. was detected by IFA from four beavers; Cryptosporidium spp. was also detected by IFA from two of these beavers. However, gene sequence data for the ssrRNA gene from these two Cryptosporidium spp.-positive beavers were inconclusive in identifying the species. Nucleotide sequences of the TPI, ssrRNA, and ??-giardin genes for Giardia spp. (deposited in GenBank) indicated that the four beavers were excreting Giardia duodenalis Assemblage B, the zoonotic genotype representing a potential source of waterborne Giardia spp. cysts. Copyright 2006 by American Association of Zoo Veterinarians.

  15. Beaver Activity, Holocene Climate and Riparian Landscape Change Across Stream Scales in the Greater Yellowstone Ecosystem

    NASA Astrophysics Data System (ADS)

    Levine, R.; Meyer, G. A.

    2013-12-01

    Beaver (Castor canadensis) have been part of the fluvial and riparian landscape across much of North America since the Pleistocene, increasing channel habitat complexity and expanding riparian landscapes. The fur trade, however, decimated beaver populations by the 1840s, and other human activities have limited beaver in many areas, including parts of the Greater Yellowstone Ecosystem (GYE). Understanding fluctuations in beaver occupation through the Holocene will aid in understanding the natural range of variability in beaver activity as well as climatic and anthropogenic impacts to fluvial systems. We are developing a detailed chronology of beaver-assisted sedimentation and overall fluvial activity for Odell and Red Rock Creeks (basin areas 83 and 99 km2) in Centennial Valley (CV), Montana, to augment related studies on the long-term effects of beaver on smaller GYE fluvial systems (basin areas 0.1-50 km2). In developing the CV chronology, we use the presence of concentrations of beaver-chewed sticks as a proxy for beaver occupancy. Beaver-stick deposits are found in paleochannel and fluvial terrace exposures. The relative ages of exposures were determined by elevation data from airborne LiDAR and ground surveys. Numerical ages were obtained from 36 14C ages (~30 more are pending) of beaver-stick wood collected during investigation of the stratigraphy. Most beaver-stick deposits are associated with ~ 1 meter of fine-grained sediment, interpreted as overbank deposits, commonly overlying gravelly sand or pebble gravel channel deposits which is consistent with enhanced overbank sedimentation associated with active beaver dams in CV streams. The CV deposits differ from those on smaller GYE streams where beaver-stick deposits are associated with abandoned dams (berms), infilled ponds and laminated sediments. The lack of pond-related deposition associated with CV beaver-stick deposits is consistent with frequent dam breaching (≤ 5 years) in the modern channel of Odell

  16. Fire effects on the Point Reyes Mountain Beaver at Point Reyes National Seashore, California

    USGS Publications Warehouse

    Fellers, Gary M.; Pratt, David; Griffin, Jennifer L.

    2004-01-01

    In October 1995, a wildlands fire burned 5,000 ha on the Point Reyes peninsula, California, USA. In most of the nonforested areas, the fire effectively cleared the ground of litter and vegetation and revealed thousands of Point Reyes mountain beaver (Aplodontia rufa phaea) burrow openings. In the first 6 months after the fire, we surveyed burned coastal scrub and riparian habitat to (1) count the number of burrow openings that existed at the time of the fire, and (2) evaluate whether signs of post-fire mountain beaver activity were evident. We estimated that only 0.4–1.7% of mountain beavers within the burn area survived the fire and immediate post-fire period. We monitored mountain beaver activity for 5 years at 8 sites where mountain beavers survived, and found little or no recovery. We estimate that the mountain beaver population will take 15–20 years post-fire to recover.

  17. Beaver Colony Density Trends on the Chequamegon-Nicolet National Forest, 1987 - 2013.

    PubMed

    Ribic, Christine A; Donner, Deahn M; Beck, Albert J; Rugg, David J; Reinecke, Sue; Eklund, Dan

    2017-01-01

    The North American beaver (Castor canadensis) is a managed species in the United States. In northern Wisconsin, as part of the state-wide beaver management program, the Chequamegon-Nicolet National Forest removes beavers from targeted trout streams on U.S. Forest Service lands. However, the success of this management program has not been evaluated. Targeted removals comprise only 3% of the annual beaver harvest, a level of effort that may not affect the beaver population. We used colony location data along Forest streams from 1987-2013 (Nicolet, northeast Wisconsin) and 1997-2013 (Chequamegon, northwest Wisconsin) to assess trends in beaver colony density on targeted trout streams compared to non-targeted streams. On the Chequamegon, colony density on non-targeted trout and non-trout streams did not change over time, while colony density on targeted trout streams declined and then stabilized. On the Nicolet, beaver colony density decreased on both non-targeted streams and targeted trout streams. However, colony density on targeted trout streams declined faster. The impact of targeted trapping was similar across the two sides of the Forest (60% reduction relative to non-targeted trout streams). Exploratory analyses of weather influences found that very dry conditions and severe winters were associated with transient reductions in beaver colony density on non-targeted streams on both sides of the Forest. Our findings may help land management agencies weigh more finely calibrated beaver control measures against continued large-scale removal programs.

  18. Beaver Colony Density Trends on the Chequamegon-Nicolet National Forest, 1987 – 2013

    PubMed Central

    Ribic, Christine A.; Donner, Deahn M.; Beck, Albert J.; Reinecke, Sue; Eklund, Dan

    2017-01-01

    The North American beaver (Castor canadensis) is a managed species in the United States. In northern Wisconsin, as part of the state-wide beaver management program, the Chequamegon-Nicolet National Forest removes beavers from targeted trout streams on U.S. Forest Service lands. However, the success of this management program has not been evaluated. Targeted removals comprise only 3% of the annual beaver harvest, a level of effort that may not affect the beaver population. We used colony location data along Forest streams from 1987–2013 (Nicolet, northeast Wisconsin) and 1997–2013 (Chequamegon, northwest Wisconsin) to assess trends in beaver colony density on targeted trout streams compared to non-targeted streams. On the Chequamegon, colony density on non-targeted trout and non-trout streams did not change over time, while colony density on targeted trout streams declined and then stabilized. On the Nicolet, beaver colony density decreased on both non-targeted streams and targeted trout streams. However, colony density on targeted trout streams declined faster. The impact of targeted trapping was similar across the two sides of the Forest (60% reduction relative to non-targeted trout streams). Exploratory analyses of weather influences found that very dry conditions and severe winters were associated with transient reductions in beaver colony density on non-targeted streams on both sides of the Forest. Our findings may help land management agencies weigh more finely calibrated beaver control measures against continued large-scale removal programs. PMID:28081271

  19. Tool-use in a display behaviour by Eurasian beavers (Castor fiber).

    PubMed

    Thomsen, Liat R; Campbell, Ruairidh D; Rosell, Frank

    2007-10-01

    Tool use is rare amongst rodents and has never been recorded in connection with agonistic displays. We witnessed a behaviour, stick display (StD), involving tool use in free-living Eurasian beavers (Castor fiber) that we conclude is a display behaviour. Two beavers were the main performers of the signal that was observed in at least six beavers from three families. Beavers reacted to displays by increased evasive and agonistic behaviours compared with their usual behavioural patterns when at territory borders. The behaviour was almost exclusively seen between rivals at territory borders. We suggest that the display is used in agonistic encounters, mainly in a territorial context.

  20. Virulence factors genes in enterococci isolated from beavers (Castor fiber).

    PubMed

    Lauková, Andrea; Strompfová, Viola; Kandričáková, Anna; Ščerbová, Jana; Semedo-Lemsaddek, Teresa; Miltko, Renata; Belzecki, Grzegorz

    2015-03-01

    Only limited information exists concerning the microbiota in beaver (Castor fiber). This study has been focused on the virulence factors genes detection in enterococci from beavers. In general, animals are not affected by enterococcal infections, but they can be a reservoir of, e.g. pathogenic strains. Moreover, detection of virulence factors genes in enterococci from beavers was never tested before. Free-living beavers (12), male and female (age 4-5 years) were caught in the north-east part of Poland. Sampling of lower gut and faeces was provided according to all ethical rules for animal handling. Samples were treated using a standard microbiological method. Pure bacterial colonies were identified by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) identification system. Virulence factors genes-gelE (gelatinase), agg (aggregation), cylA (cytolysin A), efaAfs (adhesin Enterococcus faecalis), efaAfm (adhesin Enterococcus faecium) and esp (surface protein) were tested by PCR. Moreover, gelatinase and antibiotic phenotypes were tested. Species detected were Enterococcus thailandicus, E. faecium, E. faecalis and Enterococcus durans. In literature, enterococcal species distribution was never reported yet up to now. Strains were mostly sensitive to antibiotics. Vancomycin-resistant E. faecalis EE9Tr1 possess cylA, efaAfs, esp and gelE genes. Strains were aggregation substance genes absent. Adhesin E. faecium (efaAfm) gene was detected in two of three E. faecium strains, but it was present also in E. thailandicus. Esp gene was present in EE9Tr1 and E. durans EDTr92. The most detected were gelE, efaAfm genes; in EF 4Hc1 also gelatinase phenotype was found. Strains with virulence factors genes will be tested for their sensitivity to antimicrobial enterocins.

  1. Comparison of isoflurane and sevoflurane for anesthesia in beaver.

    PubMed

    Breck, Stewart W; Gaynor, James S

    2003-04-01

    We compared the hemodynamic and respiratory effects, recovery time, and cost of two gas inhalants (isoflurane and sevoflurane) for anesthetic induction and maintenance of beaver (Castor canadensis) during surgery to implant radio transmitters in the peritoneal cavity. Heart rate, respiratory rate, relative hemoglobin saturation with oxygen (SpO2), and body temperature were measured every 5 min for the first 45 min, and arterial blood gas was measured once, 25 min into the anesthetic procedure. Induction for either agent was smooth and rapid. Heart rate and respiratory rate both decreased during the procedure though neither was lower than baseline values reported in the literature for beaver. Relative hemoglobin saturation with oxygen, body temperature, and blood gas variables did not differ between each anesthetic regime. Both inhalants caused slight respiratory acidosis. Recovery time from anesthesia was highly variable (1-178 min) but did not differ statistically between drugs. Sevoflurane costs ($22.30/60 min) were much higher than isoflurane costs ($3.50/60 min). We recommend isoflurane or sevoflurane for anesthetic induction and maintenance of beaver because of the lack of physiologic differences.

  2. Auxiliary feedwater system risk-based inspection guide for the Beaver Valley, Units 1 and 2 nuclear power plants

    SciTech Connect

    Lloyd, R.C.; Vehec, T.A.; Moffitt, N.E.; Gore, B.F.; Vo, T.V.; Rossbach, L.W.; Sena, P.P. III

    1993-02-01

    In a study sponsored by the US Nuclear Regulatory Commission (NRC), Pacific Northwest Laboratory has developed and applied a methodology for deriving plant-specific risk-based inspection guidance for the auxiliary feedwater (AFW) system at pressurized water reactors that have not undergone probabilistic risk assessment (PRA). This methodology uses existing PRA results and plant operating experience information. Existing PRA-based inspection guidance information recently developed for the NRC for various plants was used to identify generic component failure modes. This information was then combined with plant-specific and industry-wide component information and failure data to identify failure modes and failure mechanisms for the AFW system at the selected plants. Beaver Valley Units 1 and 2 were selected as two of a series of plants for study. The product of this effort is a prioritized listing of AFW failures which have occurred at the plant and at other PWRs. This listing is intended for use by NRC inspectors in the preparation of inspection plans addressing AFW risk-important components at Beaver Valley Units 1 and 2.

  3. Cross-species transmission of Giardia spp.: inoculation of beavers and muskrats with cysts of human, beaver, mouse, and muskrat origin.

    PubMed Central

    Erlandsen, S L; Sherlock, L A; Januschka, M; Schupp, D G; Schaefer, F W; Jakubowski, W; Bemrick, W J

    1988-01-01

    Giardia cysts isolated from humans, beavers, mice, and muskrats were tested in cross-species transmission experiments for their ability to infect either beavers or muskrats. Giardia cysts, derived from multiple symptomatic human donors and used for inoculation of beavers or muskrats, were shown to be viable by incorporation of fluorogenic dyes, excystation, and their ability to produce infections in the Mongolian gerbil model. Inoculation of beavers with 5 x 10(5) Giardia lamblia cysts resulted in the infection of 75% of the animals (n = 8), as judged by the presence of fecal cysts or intestinal trophozoites at necropsy. The mean prepatent period was 13.1 days. An infective dose experiment, using 5 x 10(1) to 5 x 10(5) viable G. lamblia cysts collected by fluorescence-activated cell sorting, demonstrated that doses of between, less than 50, and less than 500 viable cysts were required to produce infection in beavers. Scanning electron microscopy of beaver small intestine revealed that attachment of G. lamblia trophozoites produced lesions in the microvillous border. Inoculation of muskrats with G. lamblia cysts produced infections when the dose of cysts was equal to or greater than 1.25 x 10(5). The inoculation of beavers with Giardia ondatrae or Giardia muris cysts did not produce any infection; however, the administration to muskrats of Giardia cysts of beaver origin resulted in the infection of 62% of the animals (n = 8), with a prepatent period of 5 days. Our results demonstrated that beavers and muskrats could be infected with Giardia cysts derived from humans, but only by using large numbers of cysts.(ABSTRACT TRUNCATED AT 250 WORDS) Images PMID:3063208

  4. Impacts of beaver dams on hydrologic and temperature regimes in a mountain stream

    NASA Astrophysics Data System (ADS)

    Majerova, M.; Neilson, B. T.; Schmadel, N. M.; Wheaton, J. M.; Snow, C. J.

    2015-08-01

    Beaver dams affect hydrologic processes, channel complexity, and stream temperature in part by inundating riparian areas, influencing groundwater-surface water interactions, and changing fluvial processes within stream systems. We explored the impacts of beaver dams on hydrologic and temperature regimes at different spatial and temporal scales within a mountain stream in northern Utah over a 3-year period spanning pre- and post-beaver colonization. Using continuous stream discharge, stream temperature, synoptic tracer experiments, and groundwater elevation measurements, we documented pre-beaver conditions in the first year of the study. In the second year, we captured the initial effects of three beaver dams, while the third year included the effects of ten dams. After beaver colonization, reach-scale (~ 750 m in length) discharge observations showed a shift from slightly losing to gaining. However, at the smaller sub-reach scale (ranging from 56 to 185 m in length), the discharge gains and losses increased in variability due to more complex flow pathways with beaver dams forcing overland flow, increasing surface and subsurface storage, and increasing groundwater elevations. At the reach scale, temperatures were found to increase by 0.38 °C (3.8 %), which in part is explained by a 230 % increase in mean reach residence time. At the smallest, beaver dam scale (including upstream ponded area, beaver dam structure, and immediate downstream section), there were notable increases in the thermal heterogeneity where warmer and cooler niches were created. Through the quantification of hydrologic and thermal changes at different spatial and temporal scales, we document increased variability during post-beaver colonization and highlight the need to understand the impacts of beaver dams on stream ecosystems and their potential role in stream restoration.

  5. Beaver Dam Effects on Gravel Transport Patterns - a Case Study

    NASA Astrophysics Data System (ADS)

    Bunte, K.; Swingle, K. W.; Potyondy, J. P.; Abt, S. R.

    2011-12-01

    Beaver dams are numerous in mountain streams, but little is known about gravel transport in those streams. The dams may be fully functioning and retain all incoming sediment or partially permeable to sediment or be almost completely removed. Beaver dams in their various states of preservation can have a profound influence on stream morphology and bedload transport. During the spring of 2011, the authors made a time series study of bedload transport in a mountain stream dominated by beavers dams. Dams occurred with a frequency of one every 50 feet and showed a range of decay and fluvial influence. Gravel transport was sampled with bedload traps over a 2-month long snowmelt highflow season. The reach-average gradient was 0.03 and stream widths ranged from 3 to 8 m. The stream bed was incised 0.5 to 1.5 m deep into a floodplain and typically trapezoidal in its cross-sectional shape. Much of the floodplain consisted of filled-in beaver dams. Partially breached dams that were permeable to gravel transport acted as an obstacle, forcing the flow around sharp bends. Complex hydraulic conditions developed in the vicinity of the bends with backwater eddies upstream and downstream of the remnant dam. Wake eddies at the downstream side of dam remnants caused gravel deposits. The tortuous channel course around the bends caused strong secondary currents that forced gravel transport into a narrow pathway along one of the banks causing a strong lateral concentration of transport. The pathway had a bed of fine and medium gravel, while the remainder of the bed consisted mostly of coarse gravel and cobbles that became immobile shortly after peak flows. Tracer experiments indicated that most of the mobile gravel traveled along that bankward path, even though flow velocities and depths were considerably smaller than in the stream center. Over the highflow season, flows increased to about 160% of the 1.5 year recurrence interval (Q1.5) within about a week and then remained within the

  6. CARBON TRACE GASES IN LAKE AND BEAVER POND ICE NEAR THOMPSON, MANITOBA, CANADA

    EPA Science Inventory

    Concentrations of CO2, CO, and CH4 were measured in beaver pond and lake ice in April 1996 near Thompson, Manitoba to derive information on possible impacts of ice melting on corresponding atmospheric trace gas concentrations. CH4 concentrations in beaver pond and lake ice ranged...

  7. 76 FR 13344 - Beaver Creek Landscape Management Project, Ashland Ranger District, Custer National Forest...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-11

    ... Forest Service Beaver Creek Landscape Management Project, Ashland Ranger District, Custer National Forest... Environmental Impact Statement for the Beaver Creek Landscape Management Project in the Federal Register (75 FR... Creek Landscape Management Project was published in the Federal Register on October 15, 2010 (75...

  8. Habitat characteristics at den sites of the Point Arena mountain beaver (Aplodontia rufa nigra)

    Treesearch

    William J. Zielinski; John E. Hunter; Robin Hamlin; Keith M. Slauson; M. J. Mazurek

    2010-01-01

    The Point Arena mountain beaver (Aplodontia rufa nigra) is a federally listed endangered species, but has been the subject of few studies. Mountain beavers use burrows that include a single subterranean den. Foremost among the information needs for this subspecies is a description of the above-ground habitat features associated with dens. Using...

  9. Manipulating beaver (Castor canadensis) feeding responses to invasive tamarisk (Tamarix spp.).

    PubMed

    Kimball, Bruce A; Perry, Kelly R

    2008-08-01

    To evaluate methods for promoting consumption of tamarisk plants by beavers (Castor canadensis), we determined the feeding responses by captive beavers to diets that contained tannins and sodium chloride (hereafter referred to as tamarisk diet). In two-choice tests, beavers consumed equivalent quantities of tamarisk diet and control diet. Treatment with polyethylene glycol and fructose did not increase beaver preferences for the tamarisk diet. When offered the choice of control diet and casein hydrolysate-treated control diet, beavers strongly avoided the latter, showing feeding deterring activity of casein hydrolysate. However, when tamarisk diet was the alternative to the deterrent treatment, beavers consumed similar quantities of the two diets. Finally, beaver foraging preferences for actual plant cuttings were assessed. Casein hydrolysate application to cuttings of black poplar (Populus nigra) and Scouler's willow (Salix scouleriana) reduced browsing of these highly preferred species and promoted a marked increase in browsing of tamarisk (Tamarix ramosissima). These results suggest that casein hydrolysate treatment of desirable riparian plant species such as Salix and Populus may promote beaver foraging of invasive tamarisk.

  10. 76 FR 51469 - CSX Transportation, Inc.-Abandonment Exemption-in Beaver County, PA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-18

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF TRANSPORTATION Surface Transportation Board CSX Transportation, Inc.--Abandonment Exemption--in Beaver County, PA CSX..., between milepost PLK 0.0 and milepost PLK 2.39, in Koppel, Beaver County, Pa. The line traverses...

  11. CARBON TRACE GASES IN LAKE AND BEAVER POND ICE NEAR THOMPSON, MANITOBA, CANADA

    EPA Science Inventory

    Concentrations of CO2, CO, and CH4 were measured in beaver pond and lake ice in April 1996 near Thompson, Manitoba to derive information on possible impacts of ice melting on corresponding atmospheric trace gas concentrations. CH4 concentrations in beaver pond and lake ice ranged...

  12. An ecosystem engineer, the beaver, increases species richness at the landscape scale.

    PubMed

    Wright, Justin P; Jones, Clive G; Flecker, Alexander S

    2002-06-01

    Ecosystem engineering - the physical modification of habitats by organisms - has been proposed as an important mechanism for maintaining high species richness at the landscape scale by increasing habitat heterogeneity. Dams built by beaver (Castor canadensis) dramatically alter riparian landscapes throughout much of North America. In the central Adirondacks, New York, USA, ecosystem engineering by beaver leads to the formation of extensive wetland habitat capable of supporting herbaceous plant species not found elsewhere in the riparian zone. We show that by increasing habitat heterogeneity, beaver increase the number of species of herbaceous plants in the riparian zone by over 33% at a scale that encompasses both beaver-modified patches and patches with no history of beaver occupation. We suggest that ecosystem engineers will increase species richness at the landscape scale whenever there are species present in a landscape that are restricted to engineered habitats during at least some stages of their life cycle.

  13. Alteration of hydrogeomorphic processes by invasive beavers in southern South America.

    PubMed

    Westbrook, Cherie J; Cooper, David J; Anderson, Christopher B

    2017-01-01

    The North American beaver (Castor canadensis) is an invasive species in southern Patagonia, introduced in 1946 as part of a program by the Argentine government to augment furbearers. Research focus has turned from inventorying the beaver's population and ecosystem impacts toward eradicating it from the region and restoring degraded areas. Successful restoration, however, requires a fuller determination of how beavers have altered physical landscape characteristics, and of what landscape features and biota need to be restored. Our goal was to identify changes to the physical landscape by invasive beaver. We analyzed channel and valley morphology in detail at one site in each of the three major forest zones occurring on the Argentine side of Tierra del Fuego's main island. We also assessed 48 additional sites across the three forest biomes on the island to identify a broader range of aquatic habitat occupied and modified by beaver. Beaver build dams with Nothofagus tree branches on streams, which triggered mineral sediment accretion processes in the riparian zone, but not in ways consistent with the beaver meadow theory and only at a few sites. At the majority of sites, beavers actively excavated peat and mineral sediment, moved thousands of cubic meters of sediment within their occupied landscapes and used it to build dams. Beaver were also common in fen ecosystems where pond formation inundated and drowned peat forming mosses and sedges, and triggered a massive invasion of exotic plant species. Results highlight that restoration of fen ecosystems is a previously unrecognized but pressing and challenging restoration need in addition to reforestation of Nothofagus riparian forests. We recommend that decision-makers include the full ecosystem diversity of the Fuegian landscape in their beaver eradiation and ecosystem restoration plans. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Beaver Ponds Increase Methylmercury and Nutrients Concentrations in Canadian Shield Streams

    NASA Astrophysics Data System (ADS)

    Roy, V.; Amyot, M.; Carignan, R.

    2007-12-01

    Beaver populations and the number of beaver dams are currently increasing in many Canadian regions. Since natural and anthropogenic impoundments have historically been identified as sources of the potent neurotoxin methylmercury (MeHg), beaver dams could also increase MeHg levels in streams. During summer 2006, we collected water samples upstream and downstream from twenty beaver dams of the Laurentians, located on the Canadian Shield. Samples were analysed for total Hg, MeHg and other chemical variables including DOC, TP, TDP, TN, and major ions. Significant increases of nutrients (DOC, TP, TDP, TN) and ammonium concentrations and depletions of oxygen, nitrate and sulphate concentrations between inlet and outlet show that beaver ponds provide environmental conditions that can favour methylation of inorganic mercury. Heterogeneity of the ratio MeHg/THg at the outlet among our sites was well explained by the estimated age of the impoundment, with methylation capacity of beaver ponds decreasing with age. Further, the geographic location of beaver ponds influenced water chemistry at the outlet, as we observed a dichotomy between northern and southern sites; these differences were based mainly on forest composition. On average, beaver impoundments increased MeHg concentrations by 5.7 fold, total Hg concentrations by 1.6 fold and nutrients concentrations by 2-3 fold. Overall, our results suggest that beaver dams may considerably increase MeHg and nutrients levels in downstream ecosystems. The impact of beavers on the cycling of contaminants and nutrients in boreal watersheds should therefore be considered in the management of their populations.

  15. Habitat Evaluation Procedures (HEP) Report; Beaver Lake, Technical Report 2005.

    SciTech Connect

    Entz, Ray

    2005-05-01

    On August 14, 2003, the Habitat Evaluation Procedure (HEP) was used to determine baseline habitat suitability on the Beaver Lake property, an acquisition completed by the Kalispel Tribe of Indians in November 2002. Evaluation species and appropriate models include bald eagle, black-capped chickadee, Canada goose, mallard, muskrat, yellow warbler, and white-tailed deer. Habitat Suitability Index (HSI) values were visually estimated and agreed upon by all HEP team members. The Beaver Lake Project provides a total of 232.26 Habitat Units (HUs) for the species evaluated. Conifer forest habitat provides 136.58 HUs for bald eagle, black-capped chickadee, mallard, and white-tailed deer. Forested wetland habitat provides 20.02 HUs for bald eagle, black-caped chickadee, mallard, and white-tailed deer. Scrub-shrub wetland habitat provides 7.67 HUs for mallard, yellow warbler, and white-tailed deer. Grassland meadow provides 22.69 HUs for Canada goose and mallard. Emergent wetlands provide 35.04 HUs for Canada goose, mallard, and muskrat. Open water provided 10.26 HUs for Canada goose, mallard, and muskrat. The objective of using HEP at the Beaver Lake Project and other protected properties is to document the quality and quantity of available habitat for selected wildlife species. In this way, HEP provides information on the relative value of the same area at future points in time so that the effect of management activities on wildlife habitat can be quantified. When combined with other tools, the baseline HEP will be used to determine the most effective on-site management, restoration, and enhancement actions to increase habitat suitability for targeted species. The same process will be replicated every five years to quantitatively evaluate the effectiveness of management strategies in improving and maintaining habitat conditions while providing additional crediting to BPA for enhanced habitat values.

  16. The beaver Anchitheriomys from the Miocene of Central Europe

    SciTech Connect

    Stefen, C.; Mors, T.

    2008-09-15

    New finds of teeth and mandibles of Anchitheriomys from the Hambach opencast lignite mine in Northwest Germany and the first detailed descriptions of other mandibles from South Germany and Switzerland allow a review of the Central European specimens of this rare beaver genus. The metric variation of cheek teeth and especially the great differences in dimensions of incisors can be much better assessed. The observed range in size can be attributed to ontogenetic changes, and all material is assigned to Anchitheriomys suevicus. Stratigraphically, this species is restricted to the early middle Miocene, European Mammalian Neogene biozones MN 5-6.

  17. Influence of Beaver Dams on Channel Complexity, Hydrology, and Temperature Regime in a Mountainous Stream

    NASA Astrophysics Data System (ADS)

    Majerova, M.; Neilson, B. T.; Schmadel, N. M.; Wheaton, J. M.; Snow, C. J.

    2013-12-01

    Beaver dams and beaver activity affect hydrologic processes, sediment transport, channel complexity and water quality of streams. Beaver ponds, which form behind beaver dams, increase in-channel water storage affecting the timing and volume of flow and resulting in the attenuation and flattening of the hydrograph. Channel complexity also increases the potential for transient storage (both surface and subsurface) and influences stream temperature. Impacts of beaver dams and beaver activity on stream responses are difficult to quantify because responses are dynamic and spatially variable. Few studies have focused on the reach scale temporal influences on stream responses and further research is needed particularly in quantifying the influence of beaver dams and their role in shaping the stream habitat. This study explores the changing hydrology and temperature regime of Curtis Creek, a mountainous stream located in Northern Utah, in a 560 m long reach where groundwater exchanges and temperature differences were observed over a three-year period. We have collected continuous stream discharge, stream temperature data and performed tracer experiments. During the first year, we were able to capture the pre-beaver activity. In the second year, we captured the impacts of some beaver activity with only a few dams built in the reach, while the third year included the effects of an entire active beaver colony. By the end of the study period, a single thread channel had been transformed into a channel with side channels and backwaters at multiple locations therefore increasing channel complexity. The cumulative influence of beaver dams on reach scale discharge resulted in a slightly losing reach that developed into a gaining reach. At the smaller sub-reach scale, both losing to gaining and gaining to losing transformations were observed. Temperature differences showed a warming effect of beaver dams at the reach scale. The reach stream temperature difference increased on

  18. Influence of beaver activity on summer growth and condition of age-2 Atlantic salmon parr

    USGS Publications Warehouse

    Sigourney, Douglas B.; Letcher, B.H.; Cunjak, R.A.

    2006-01-01

    The activity of beavers Castor canadensis in freshwater environments can have considerable localized impacts on the physical and biological components of riparian ecosystems. By changing the habitat of a stream, beaver dams can cause spatial variation in growth opportunity that may have direct consequences for the growth of resident fish. In a small stream in eastern Canada, we studied the effects of an ephemeral beaver pond on the growth and maturity of age-2 Atlantic salmon Salmo salar parr tagged with passive integrated transponder tags. Water temperature remained relatively uniform throughout the study site. We found very little movement of recaptured fish in the study site. Fish that were recaptured in the beaver pond displayed faster summer growth rates in both length and mass than fish that were recaptured immediately above or below the pond. We also found that parr in the pond maintained relatively high condition factors, whereas fish above and below the pond appeared to decrease in condition factor throughout the summer. In addition to growth, the maturation rates of age-2 males were higher above the dam than below. This study demonstrates the effect a beaver dam can have on individual growth rates. By influencing growth during sensitive periods, the beaver pond may also influence individual life history pathways. This information could be an important component in ecosystem models that predict the effect of beaver population dynamics on the growth of individual salmonids at the landscape scale. ?? Copyright by the American Fisheries Society 2006.

  19. Modeling Potential Surface and Shallow Groundwater Storage Provided by Beaver Ponds Across Watersheds

    NASA Astrophysics Data System (ADS)

    Hafen, K.; Wheaton, J. M.; Macfarlane, W.

    2016-12-01

    Damming of streams by North American Beaver (Castor canadensis) has been shown to provide a host of potentially desirable hydraulic and hydrologic impacts. Notably, increases in surface water storage and groundwater storage may alter the timing and delivery of water around individual dams and dam complexes. Anecdotal evidence suggests these changes may be important for increasing and maintaining baseflow and even helping some intermittent streams flow perennially. In the arid west, these impacts could be particularly salient in the face of climate change. However, few studies have examined the hydrologic impacts of beaver dams at scales large enough to provide insight for water management, in part because understanding or modeling these impacts at large spatial scales has been precluded by uncertainty concerning the number of beaver dams a drainage network can support. Using the recently developed Beaver Restoration Assessment Tool (BRAT) to identify possible densities and spatial configurations of beaver dams, we developed a model that predicts the area and volume of surface water storage associated with dams of various sizes, and applied this model at different dam densities across multiple watersheds (HUC12) in northern Utah. We then used model results as inputs to the MODFLOW groundwater model to identify the subsequent changes to shallow groundwater storage. The spatially explicit water storage estimates produced by our approach will be useful in evaluating potential beaver restoration and conservation, and will also provide necessary information for developing hydrologic models to specifically identify the effects beaver dams may have on water delivery and timing.

  20. Ground water in the alluvium of Beaver Creek basin, Oklahoma

    USGS Publications Warehouse

    Hart, D.L.

    1961-01-01

    Beaver Creek is an 857 square-mile area in south-central Oklahoma. The tributaries head at an altitude as high as 1,400 feet and the mouth of Beaver Creek is at an altitude of 804 feet. Alluvial material has been deposited along all the major streams in the basin. The alluvium contains a high percentage of clay and fine sand and ranges in thickness from a few inches to 50 feet. Replenishment of water in the alluvium is from precipitation, lateral seepage and runoff from adjoining areas, and infiltration from the streams during high flows. The town of Ryan and Waurika have constructed municipal water-supply wells topping the alluvium and residents of the town of Sugden have private wells topping the alluvium. The other major use of ground water is transpiration by trees, which are very dense where the alluvial plain is wide. In the northern part of the basin the alluvium is thin and only domestic water supplies are available. (available as photostat copy only)

  1. Transition to independence by subadult beavers (Castor canadensis) in an unexploited, exponentially growing population

    USGS Publications Warehouse

    DeStefano, S.; Koenen, Kiana K. G.; Henner, C.M.; Strules, J.

    2006-01-01

    We conducted a 4-year study of beavers Castor canadensis to compare the movements, survival and habitat of adults established in existing colonies to juveniles dispersing to new sites in a region with high beaver densities along a suburban-rural gradient. Estimates of annual survival were high for adult and juvenile beavers. Of nine known mortalities, seven (78%) were juveniles. Mortalities occurred during spring-summer, and none during fall-winter. There was a trend toward higher-to-lower survival along the suburban-rural gradient, respectively. Human-induced mortality (e.g. trapping and shooting) was higher in rural areas, whereas nonhuman-induced mortality (e.g. disease, accidents) was higher in suburban areas. Fifteen (14 subadults and one adult) beavers moved from natal colonies to other areas. The average dispersal distance for subadults was 4.5 km (SE = 1.0) along streams or rivers, or 3.5 km (SE = 0.7) straight-line point-to-point. Most dispersal movements were made in spring (April-June). In two cases, individual subadults made return movements from their dispersal sites back to their natal colonies. Dispersal sites tended to be in smaller, shallower wetlands or streams and in areas with higher overstorey canopy closure compared with natal colonies. Woody vegetation usually preferred by beavers for food tended to be less common at dispersal sites than at natal colonies. In regions with high densities of beaver, dispersing juveniles are likely to attempt to colonize lower quality sites. High densities of beavers also lead to more human-beaver conflicts and, in Massachusetts, the pest control management options in place during the past decade have been ineffectual at controlling population levels. Alternately, in regions with no beavers or very low densities and where reintroductions are being attempted, the landscape matrix surrounding release sites should include suitable sites for dispersing young to establish colonies.

  2. Haematology and Serum Biochemistry Parameters and Variations in the Eurasian Beaver (Castor fiber)

    PubMed Central

    Girling, Simon J.; Campbell-Palmer, Roisin; Pizzi, Romain; Fraser, Mary A.; Cracknell, Jonathan; Arnemo, Jon; Rosell, Frank

    2015-01-01

    Haematology parameters (N = 24) and serum biochemistry parameters (N = 35) were determined for wild Eurasian beavers (Castor fiber), between 6 months – 12 years old. Of the population tested in this study, N = 18 Eurasian beavers were from Norway and N = 17 originating from Bavaria but now living extensively in a reserve in England. All blood samples were collected from beavers via the ventral tail vein. All beavers were chemically restrained using inhalant isoflurane in 100% oxygen prior to blood sampling. Results were determined for haematological and serum biochemical parameters for the species and were compared between the two different populations with differences in means estimated and significant differences being noted. Standard blood parameters for the Eurasian beaver were determined and their ranges characterised using percentiles. Whilst the majority of blood parameters between the two populations showed no significant variation, haemoglobin, packed cell volume, mean cell haemoglobin and white blood cell counts showed significantly greater values (p<0.01) in the Bavarian origin population than the Norwegian; neutrophil counts, alpha 2 globulins, cholesterol, sodium: potassium ratios and phosphorus levels showed significantly (p<0.05) greater values in Bavarian versus Norwegian; and potassium, bile acids, gamma globulins, urea, creatinine and total calcium values levels showed significantly (p<0.05) greater values in Norwegian versus Bavarian relict populations. No significant differences were noted between male and female beavers or between sexually immature (<3 years old) and sexually mature (≥3 years old) beavers in the animals sampled. With Eurasian beaver reintroduction encouraged by legislation throughout Europe, knowledge of baseline blood values for the species and any variations therein is essential when assessing their health and welfare and the success or failure of any reintroduction program. This is the first study to produce base

  3. Impact of beaver ponds on river discharge and sediment deposition along the Chevral River, Ardennes, Belgium

    NASA Astrophysics Data System (ADS)

    Nyssen, Jan; Frankl, Amaury; Pontzeele, Jolien; De Visscher, Maarten; Billi, Paolo

    2013-04-01

    With the recovery of the European beaver (Castor fiber) and their capacity to engineer fluvial landscapes, questions arise as to how they influence river discharge and sediment transport. The Chevral river (Ardennes, Belgium) contains two beaver dam sequences which appeared in 2004 and count now about 30 dams. Flow discharges and sediment fluxes were measured at the in- and outflow of each dam sequence. Volumes of sediment deposited behind the dams were measured. Between 2004 and 2011, peak flows were topped off, and the magnitude of extreme events decreased. 1710 m³ of sediment were deposited behind the beaver dams, with an average sediment thickness of 25 cm. The thickness of the sediment layer is related to the area of the beaver ponds. Along the stream, beaver pond sediment thickness displayed a sinusoidal deposition pattern, in which ponds with thick sediment layers were preceded by a series of ponds with thinner sediment layers. A downstream textural coarsening in the dam sequences was also observed, probably due to dam failures subsequent to surges. Differences in sediment flux between the in- and outflow at the beaver pond sequence were related to the river hydrograph, with deposition taking place during the rising limbs and slight erosion during the falling limbs. The seven-year-old sequences have filtered 190 tons of sediment out of the Chevral river, which is of the same order of magnitude as the 374 tons measured in pond deposits, with the difference between the values corresponding to beaver excavations (60 tons), inflow from small tributaries, and runoff from the valley flanks. Hydrogeomorphic effects of C. fiber and C. canadensis activity are similar in magnitude. The detailed analysis of changes to hydrology in beaver pond sequences confirms the potential of beavers to contribute to river and wetland restoration and catchment management.

  4. Haematology and Serum Biochemistry Parameters and Variations in the Eurasian Beaver (Castor fiber).

    PubMed

    Girling, Simon J; Campbell-Palmer, Roisin; Pizzi, Romain; Fraser, Mary A; Cracknell, Jonathan; Arnemo, Jon; Rosell, Frank

    2015-01-01

    Haematology parameters (N = 24) and serum biochemistry parameters (N = 35) were determined for wild Eurasian beavers (Castor fiber), between 6 months - 12 years old. Of the population tested in this study, N = 18 Eurasian beavers were from Norway and N = 17 originating from Bavaria but now living extensively in a reserve in England. All blood samples were collected from beavers via the ventral tail vein. All beavers were chemically restrained using inhalant isoflurane in 100% oxygen prior to blood sampling. Results were determined for haematological and serum biochemical parameters for the species and were compared between the two different populations with differences in means estimated and significant differences being noted. Standard blood parameters for the Eurasian beaver were determined and their ranges characterised using percentiles. Whilst the majority of blood parameters between the two populations showed no significant variation, haemoglobin, packed cell volume, mean cell haemoglobin and white blood cell counts showed significantly greater values (p<0.01) in the Bavarian origin population than the Norwegian; neutrophil counts, alpha 2 globulins, cholesterol, sodium: potassium ratios and phosphorus levels showed significantly (p<0.05) greater values in Bavarian versus Norwegian; and potassium, bile acids, gamma globulins, urea, creatinine and total calcium values levels showed significantly (p<0.05) greater values in Norwegian versus Bavarian relict populations. No significant differences were noted between male and female beavers or between sexually immature (<3 years old) and sexually mature (≥3 years old) beavers in the animals sampled. With Eurasian beaver reintroduction encouraged by legislation throughout Europe, knowledge of baseline blood values for the species and any variations therein is essential when assessing their health and welfare and the success or failure of any reintroduction program. This is the first study to produce base

  5. Hydrological and geomorphological consequences of beavers activity in the Struga Czechowska valley (Tuchola Pinewood Forest, Poland)

    NASA Astrophysics Data System (ADS)

    Brykała, Dariusz; Gierszewski, Piotr; Błaszkiewicz, Mirosław; Kordowski, Jarosław; Tyszkowski, Sebastian; Słowiński, Michał; Kaszubski, Michał; Brauer, Achim

    2016-04-01

    Since last years, after the process of beavers' (Castor fiber) reintroduction to the Polish environment, on the Struga Czechowska river (Tuchola Pinewood Forest, Poland) was observed large beaver activity, especially along the outlet from the Lake Głęboczek. It expresses in relief transformation of the valley bottom and its slopes. Created by beavers small ponds functioning as local sediment traps. Periodically the dams were destroyed. This led to rapid water drainage. The effects of such events were observed in the period between December 2014 and May 2015. Inventory of beaver dams along the Struga Czechowska river, which had made in 2015, shows that dams were distributed on average every 50 m. There were 30 dams on three sections of river. Only 6 were built there in 2015, and the remaining were older and abandoned, but one-third of them still damming water of stream. The average water damming by beaver dams amounts 0.2 m, and maximum 0.6 m. The width of the beaver dams reached there almost always the value of 3 m, and their height reached average up to 0.8 m was identical to the bankfull depth. Cascade character of the beaver dams operation has its consequences in functioning of erosional and accumulation parts of watercourses (alternately). Analysis of hydrograph of the Struga Czechowska water levels shows, that since December 2014 there were nine rapid drainages of beaver ponds located above the paleolake Trzechowskie. Damaged dams were very quickly rebuilt, and water in ponds was again stored. The average time of restoration the dam amounts 10 hours, and maximum 3 days. Rapid flows from beaver ponds resulted in intensive bottom and lateral erosion of stream channel and a creation of soil falls on the slopes of valley below destroyed dams. Products of erosion were accumulated along watercourse at a distance of 200 meters, and then in the stream channel in form of sandy bars. Especially intensive accumulation occurred at flat surface of paleolake. Maximum

  6. Holocene Beaver Effects on Small Streams in Yellowstone and Implications for Stream Restoration

    NASA Astrophysics Data System (ADS)

    Persico, L. P.; Meyer, G.

    2005-12-01

    It has been asserted that beaver ( Castor canadensis) damming has sustained long-term aggradation and exerted a dominant control on the morphology of small streams over much of North America. However, data on the temporal and spatial dimensions of beaver influence are extremely limited. Using beaver pond deposits and berms (abandoned dams), we document geomorphic effects of beavers on first- to fourth-order streams in semiarid-subhumid northern Yellowstone National Park, USA. Beavers were ubiquitous in the early 20th century, but are currently rare. Some formerly dammed streams have become ephemeral in recent droughts, suggesting that climate may be a significant factor controlling beaver occupation. Radiocarbon dating of wood preserved in pond deposits and berms shows notable periods of beaver activity 3655-3855, 1555-955, and 455-150 cal yr BP, but a distinct lack of activity 950-700 cal yr BP during the Medieval Climatic Anomaly, a time of severe multidecadal droughts in Yellowstone and the western USA. The spatial scale over which beavers incurred significant aggradation is controlled largely by geomorphic settings conducive to damming. Low-gradient (0.07 to 0.001) reaches with contributing areas of 4 to 70 km2 are typical for dam sites. Reaches with downstream valley constrictions are most susceptible to aggradation. Only a small fraction of the total stream length in the study area has experienced significant aggradation attributable to beaver damming, as shown by accumulations of sand and finer sediment of up to 3 m, thicker than typical overbank sediments. These sediments locally contain evidence of ponding in laminations, gleying, and high organic content. Many reaches show no evidence of any net aggradation since deglaciation. Many beaver-aggraded reaches are now incised, typically 1.5-2 m and up to 3 m. Some reaches have early Holocene (ca. 10150-8000 cal yr BP) terraces with treads ~2 m above current bankfull level, underlain by both gravelly and fine

  7. Simulation modeling to understand how selective foraging by beaver can drive the structure and function of a willow community

    USGS Publications Warehouse

    Peinetti, H.R.; Baker, B.W.; Coughenour, M.B.

    2009-01-01

    Beaver-willow (Castor-Salix) communities are a unique and vital component of healthy wetlands throughout the Holarctic region. Beaver selectively forage willow to provide fresh food, stored winter food, and construction material. The effects of this complex foraging behavior on the structure and function of willow communities is poorly understood. Simulation modeling may help ecologists understand these complex interactions. In this study, a modified version of the SAVANNA ecosystem model was developed to better understand how beaver foraging affects the structure and function of a willow community in a simulated riparian ecosystem in Rocky Mountain National Park, Colorado (RMNP). The model represents willow in terms of plant and stem dynamics and beaver foraging in terms of the quantity and quality of stems cut to meet the energetic and life history requirements of beaver. Given a site where all stems were equally available, the model suggested a simulated beaver family of 2 adults, 2 yearlings, and 2 kits required a minimum of 4 ha of willow (containing about10 stems m-2) to persist in a steady-state condition. Beaver created a willow community where the annual net primary productivity (ANPP) was 2 times higher and plant architecture was more diverse than the willow community without beaver. Beaver foraging created a plant architecture dominated by medium size willow plants, which likely explains how beaver can increase ANPP. Long-term simulations suggested that woody biomass stabilized at similar values even though availability differed greatly at initial condition. Simulations also suggested that willow ANPP increased across a range of beaver densities until beaver became food limited. Thus, selective foraging by beaver increased productivity, decreased biomass, and increased structural heterogeneity in a simulated willow community.

  8. Changes in local mosquito fauna following beaver (Castor canadensis) activity--an update.

    PubMed

    Butts, W L

    1992-09-01

    Drastic reduction of populations of univoltine temporary pool mosquitoes followed impoundment of breeding areas by beavers. Mosquito populations persist at very low levels over a 10-year period with no evidence of mosquito development in the impoundment.

  9. Beaver-mediated methane emission: The effects of population growth in Eurasia and the Americas.

    PubMed

    Whitfield, Colin J; Baulch, Helen M; Chun, Kwok P; Westbrook, Cherie J

    2015-02-01

    Globally, greenhouse gas budgets are dominated by natural sources, and aquatic ecosystems are a prominent source of methane (CH(4)) to the atmosphere. Beaver (Castor canadensis and Castor fiber) populations have experienced human-driven change, and CH(4) emissions associated with their habitat remain uncertain. This study reports the effect of near extinction and recovery of beavers globally on aquatic CH4 emissions and habitat. Resurgence of native beaver populations and their introduction in other regions accounts for emission of 0.18-0.80 Tg CH(4) year(-1) (year 2000). This flux is approximately 200 times larger than emissions from the same systems (ponds and flowing waters that became ponds) circa 1900. Beaver population recovery was estimated to have led to the creation of 9500-42 000 km(2) of ponded water, and increased riparian interface length of >200 000 km. Continued range expansion and population growth in South America and Europe could further increase CH(4) emissions.

  10. Nitrogen budget of a subarctic stream altered by beaver (Castor canadensis).

    PubMed

    Naiman, Robert J; Melillo, Jerry M

    1984-05-01

    Beaver (Castor canadensis) influence stream ecosystems through their wood cutting and dam building activities. To quantify this influence we have used measured rates of nitrogen dynamics to construct a nitrogen budget for a section of a second order stream in eastern Québec and a beaver dam in that stream. The budget demonstrates the importance of sediment accumulations and an expanded wetted area to the annual nitrogen economy and to pathways of nitrogen cycling. Major changes after impoundment (per unit area) include a reduction in allochthonous nitrogen and an increase in nitrogen fixation by sediment microbes. Overall, the beaver-modified section accumulated ∼10(3) times more nitrogen than before alteration. The ecosystem implications of beaver activity suggest that current concepts of patterns and processes in running waters require modification.

  11. Electrofishing method improves evaluation of amphibian larvae abundance: a case of "beaver rivers".

    PubMed

    Dgebuadze, Yury Y; Bashinskiy, Ivan V

    2017-07-01

    There are many locations in Russia where Eurasian beaver (Castor fiber) populations have been restored. As a keystone species, beavers provide wide-ranging direct and indirect impacts on aquatic ecosystems. In particular, beaver-created ponds are sites for spawning and nursery places for tadpoles of the brown frogs (genus Rana). Because of such impacts, study techniques for assessing aquatic organism abundance are being developed. We compared two methods for estimating tadpole abundance: traditional catches by dipnet and electrofishing. Our results show that the dipnet catch data for the shallower ponds with larger water surface area were five times lower than that obtained by electrofishing. Therefore, we conclude that dipnet catches are not suitable for comparing the relative abundance of tadpoles in the two beaver ponds that were studied. © 2016 International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and John Wiley & Sons Australia, Ltd.

  12. Immunoblotting for the serodiagnosis of alveolar echinococcosis in alive and dead Eurasian beavers (Castor fiber).

    PubMed

    Gottstein, B; Frey, C F; Campbell-Palmer, R; Pizzi, R; Barlow, A; Hentrich, B; Posautz, A; Ryser-Degiorgis, M-P

    2014-09-15

    A novel species-specific anti-beaver-IgG-alkaline-phosphatase conjugate was synthesized for the development of a new serological test for echinococcosis in beavers. Two different ELISAs conventionally used for human Echinococcus multilocularis serology (Em18-ELISA and Em2-ELISA) yielded diagnostic sensitivities of 0% and 46%, respectively. In contrast, the subsequently developed immunoblotting assay gave an 85% diagnostic sensitivity (11 out of 13 beavers with alveolar echinococcosis were immunoblotting-positive, i.e. showed reactivity with a specific 21 Mr band), and maximal specificity. In conclusion, this immunoblotting assay should be the method of choice for use in serological studies on E. multilocularis in Eurasian beavers, and the test proved suitable to investigate both animals alive and post-mortem.

  13. Modeling the Capacity of Riverscapes to Support Dam-Building Beaver

    NASA Astrophysics Data System (ADS)

    Macfarlane, W.; Wheaton, J. M.

    2012-12-01

    Beaver (Castor canadensis) dam-building activities lead to a cascade of aquatic and riparian effects that increase the complexity of streams. As a result, beaver are increasingly being used as a critical component of passive stream and riparian restoration strategies. We developed the spatially-explicit Beaver Assessment and Restoration Tool (BRAT) to assess the capacity of the landscape in and around streams and rivers to support dam-building activity for beaver. Capacity was assessed in terms of readily available nation-wide GIS datasets to assess key habitat capacity indicators: water availability, relative abundance of preferred food/building materials and stream power. Beaver capacity was further refined by: 1) ungulate grazing capacity 2) proximity to human conflicts (e.g., irrigation diversions, settlements) 3) conservation/management objectives (endangered fish habitat) and 4) projected benefits related to beaver re-introductions (e.g., repair incisions). Fuzzy inference systems were used to assess the relative importance of these inputs which allowed explicit incorporation of uncertainty resulting from categorical ambiguity of inputs into the capacity model. Results indicate that beaver capacity varies widely within the study area, but follows predictable spatial patterns that correspond to distinct River Styles and landscape units. We present a case study application and verification/validation data from the Escalante River Watershed in southern Utah, and show how the models can be used to help resource managers develop and implement restoration and conservation strategies employing beaver that will have the greatest potential to yield increases in biodiversity and ecosystem services.

  14. Scrub-shrub bird habitat associations at multiple spatial scales in beaver meadows in Massachusetts

    USGS Publications Warehouse

    Chandler, R.B.; King, D.I.; DeStefano, S.

    2009-01-01

    Most scrub-shrub bird species are declining in the northeastern United States, and these declines are largely attributed to regional declines in habitat availability. American Beaver (Castor canadensis; hereafter “beaver”) populations have been increasing in the Northeast in recent decades, and beavers create scrub-shrub habitat through their dam-building and foraging activities. Few systematic studies have been conducted on the value of beaver-modified habitats for scrub-shrub birds, and these data are important for understanding habitat selection of scrub-shrub birds as well as for assessing regional habitat availability for these species. We conducted surveys in 37 beaver meadows in a 2,800-km2 study area in western Massachusetts during 2005 and 2006 to determine the extent to which these beaver-modified habitats are used by scrub-shrub birds, as well as the characteristics of beaver meadows most closely related to bird use. We modeled bird abundance in relation to microhabitat-, patch-, and landscape-context variables while adjusting for survey-specific covariates affecting detectability using N-mixture models. We found that scrub-shrub birds of regional conservation concern occupied these sites and that birds responded differently to microhabitat, patch, and landscape characteristics of beaver meadows. Generally, scrub-shrub birds increased in abundance along a gradient of increasing vegetation complexity, and three species were positively related to patch size. We conclude that these habitats can potentially play an important role in regional conservation of scrub-shrub birds and recommend that conservation priority be given to larger beaver meadows with diverse vegetation structure and composition.

  15. Channel aggradation by beaver dams on a small agricultural stream in Eastern Nebraska

    Treesearch

    M.C. McCullough; J.L. Harper; D.E. Eisenhauer; M.G. Dosskey

    2004-01-01

    We assessed the effect of beaver dams on channel gradation of an incised stream in an agricultural area of eastern Nebraska. A topographic survey was conducted of a reach of Little Muddy Creek where beaver are known to have been building dams for twelve years. Results indicating that over this time period the thalweg elevation has aggraded an average of 0.65 m by...

  16. The chromosomes of the Canadian Beaver Castor canadensis.

    PubMed

    Genest, F B; Morisset, P; Patenaude, R P

    1979-03-01

    A chromosome analysis of 24 Canadian beavers, Castor canadensis Kuhl (12 males and 12 females), captured in Laurentides Park, Qébec, has been performed from preparations of blood lymphocyte and skin cultures. The chromosome number was found to be 2n = 40. Measurements were made to determine relative lengths and arm ratios of chromosomes, which are metacentric or submetacentric. Results are in agreement with those already published regarding the chromosome number, but differ in the identification of the X chromosome, and in the morphology of the Y and some autosomes. C- ad G-banding techniques allowed the precise identification of individual chromosome pairs. A detailed idiogram of G-bands is presented.

  17. Rodents for comparative aging studies: from mice to beavers

    PubMed Central

    Bozzella, Michael J.; Seluanov, Andrei

    2008-01-01

    After humans, mice are the best-studied mammalian species in terms of their biology and genetics. Gerontological research has used mice and rats extensively to generate short- and long-lived mutants, study caloric restriction and more. Mice and rats are valuable model organisms thanks to their small size, short lifespans and fast reproduction. However, when the goal is to further extend the already long human lifespan, studying fast aging species may not provide all the answers. Remarkably, in addition to the fast-aging species, the order Rodentia contains multiple long-lived species with lifespans exceeding 20 years (naked mole-rat, beavers, porcupines, and some squirrels). This diversity opens great opportunities for comparative aging studies. Here we discuss the evolution of lifespan in rodents, review the biology of slow-aging rodents, and show an example of how the use of a comparative approach revealed that telomerase activity coevolved with body mass in rodents. PMID:19424861

  18. Pheromonal activity of single castoreum constituents in beaver,Castor canadensis.

    PubMed

    Müller-Schwarze, D; Houlihan, P W

    1991-04-01

    Behavioral activity of single components of beaver castoreum was demonstrated for the first time. In four experiments samples were presented to free-ranging beaver in their family territories. First, responses to whole castoreum and anal gland secretion (AGS) from males and females were tested. Second, 24 compounds, known to be constituents of beaver castoreum, were individually screened for activity. Four of these consistently released immediate responses during the observation periods. These are the phenols 4-ethylphenol and 1,2-dihydroxybenzene and the ketones acetophenone and 3-hydroxyacetophenone. In the most complete responses, the beaver sniffed from the water, were attracted to the odor, swam toward its source, went on land, and then approached, sniffed, pawed, and scent-marked the artificial scent mound. 4-Ethoxyphenol, a compound not yet found in castoreum, also released these responses. Five additional compounds resulted in a few delayed visits to the samples during the night following the observations, as evidenced by destroyed scent mounds. These are 4-methyl-1,2-dihydroxybenzene, 4-methoxyacetophenone, 5-methoxysalicylic acid, salicylaldehyde, and 3-hydroxybenzoic acid. Third, mixtures of 24 and six compounds were tested. Responses to these mixtures could be as strong as those to whole castoreum. Fourth, the four regularly active compounds were tested in two additional beaver populations and proved to be active there, too. The response was strongest in the densest beaver population.

  19. Giardia in beaver (Castor canadensis) and nutria (Myocastor coypus) from east Texas.

    PubMed

    Dunlap, Brett G; Thies, Monte L

    2002-12-01

    We examined the prevalence of Giardia sp. infection in nuisance beaver (Castor canadensis) and nutria (Myocastor coypus) in east Texas. From October 1992 through September 1993, 100 beaver and 30 nutria were collected in routine wildlife management activities conducted by the U.S. Department of Agriculture-Animal and Plant Health Inspection Service-Texas Animal Damage Control Service. Fecal and duodenal mucoid samples were preserved from each animal. Fecal samples were examined for the occurrence of Giardia sp. cysts using the Merifluor immunoassay detection kit: 30 beaver (30.0%) and 20 nutria (66.7%) were positive for Giardia sp. Duodenal mucoid samples were examined for Giardia sp. trophozoites using trichrome staining. with 26 beaver (26.0%) and 20 nutria (73.3%) testing positive. Combining both techniques resulted in 33 beaver (33.0%) and 22 nutria (73.3%) testing positive for Giardia sp. We found no relationship between Giardia sp. and host age, sex, river system, habitat, county, or season in beaver. However, a relationship was found when season and habitat were considered together. No relationship was found between Giardia sp. and age, river system, habitat, county, or season in nutria: however, more males (87.5%) were infected than females (46.4%).

  20. The hydrological modeling in terms of determining the potential European beaver effect

    NASA Astrophysics Data System (ADS)

    Szostak, Marta; Jagodzińska, Jadwiga

    2017-06-01

    The objective of the paper was the hydrological analysis, in terms of categorizing main watercourses (based on coupled catchments) and marking areas covered by potential impact of the occurrence and activities of the European beaver Castor fiber. At the analysed area - the Forest District Głogów Małopolski there is a population of about 200 beavers in that Forest District. Damage inflicted by beavers was detected on 33.0 ha of the Forest District, while in the area of 13.9 ha the damage was small (below 10%). The monitoring of the beavers' behaviour and the analysis of their influence on hydrology of the area became an important element of using geoinformationtools in the management of forest areas. ArcHydro ArcGIS Esri module was applied, as an integrated set of tools for hydrographical analysis and modelling. Further steps of the procedure are hydrologic analyses such as: marking river networks on the DTM, filling holes, making maps of the flow direction, making the map of the accumulation flow, defining and segmentation of streams, marking elementary basins, marking coupled basins, making dams in the places, where beavers occur and localization of the area with a visible impact of damming. The result of the study includes maps prepared for the Forest District: the map of main rivers and their basins, categories of watercourses and compartments particularly threatened by beaver's foraging.

  1. Beaver lodge distributions and damage assessments in a forested wetland ecosystem in the southern United States

    USGS Publications Warehouse

    King, S.L.; Keeland, B.D.; Moore, J.L.

    1998-01-01

    Caddo Lake, USA, a Ramsar Wetland of International Importance, is a lacustrine wetland complex consisting of stands of flooded baldcypress intermixed with open water and emergent wetland habitats. Recently, concern has been expressed over a perceived increase in the beaver population and the impact of beaver on the long-term sustainability of the baldcypress ecosystem. We used intensive beaver lodge surveys to determine the distribution and relative abundance of beaver and the amount, type, and distribution of beaver damage to mature trees and seedlings at Caddo Lake. A total of 229 lodges were located with a combination of aerial and boat/ground surveys. Most lodges were located in open water and edge habitats. About 95% of the lodges were occupied by beaver or nutria. Some form of damage was exhibited by one or more trees near 85% of the lodges. Intensive damage assessments around 35 lodges indicated that most damage to trees, baldcypress in particular, was restricted to peeling or stripping of bark which is believed to have minimal effect on tree survival. Surveys of regeneration indicated that baldcypress seedlings were very abundant; however, over 99.9% were less than 30 cm tall. The lack of recruitment into the larger size classes appears to be a result of high stand densities and water management practices. At this time, the young age and density of the baldcypress forests suggest that recruitment is not a major concern and herbivore damage appears to be having a minimal effect on the forest.

  2. Design to monitor trend in abundance and presence of American beaver (Castor canadensis) at the national forest scale.

    PubMed

    Beck, Jeffrey L; Dauwalter, Daniel C; Gerow, Kenneth G; Hayward, Gregory D

    2010-05-01

    Wildlife conservationists design monitoring programs to assess population dynamics, project future population states, and evaluate the impacts of management actions on populations. Because agency mandates and conservation laws call for monitoring data to elicit management responses, it is imperative to design programs that match the administrative scale for which management decisions are made. We describe a program to monitor population trends in American beaver (Castor canadensis) on the US Department of Agriculture, Black Hills National Forest (BHNF) in southwestern South Dakota and northeastern Wyoming, USA. Beaver have been designated as a management indicator species on the BHNF because of their association with riparian and aquatic habitats and its status as a keystone species. We designed our program to monitor the density of beaver food caches (abundance) within sampling units with beaver and the proportion of sampling units with beavers present at the scale of a national forest. We designated watersheds as sampling units in a stratified random sampling design that we developed based on habitat modeling results. Habitat modeling indicated that the most suitable beaver habitat was near perennial water, near aspen (Populus tremuloides) and willow (Salix spp.), and in low gradient streams at lower elevations. Results from the initial monitoring period in October 2007 allowed us to assess costs and logistical considerations, validate our habitat model, and conduct power analyses to assess whether our sampling design could detect the level of declines in beaver stated in the monitoring objectives. Beaver food caches were located in 20 of 52 sampled watersheds. Monitoring 20 to 25 watersheds with beaver should provide sufficient power to detect 15-40% declines in the beaver food cache index as well as a twofold decline in the odds of beaver being present in watersheds. Indices of abundance, such as the beaver food cache index, provide a practical measure of

  3. Downstream Influences of Beaver Impoundments on the Biogeochemical Characteristics of a New England Stream

    NASA Astrophysics Data System (ADS)

    Moulton, L. A.; Bubier, J.; Kyker-Snowman, T.

    2001-05-01

    A study was conducted from June to August 2000 in a tributary stream of the Quabbin Reservoir, water supply to metropolitan Boston, to investigate the effects of beaver (Castor canadensis) populations on stream water quality. Spatial and temporal trends of parameters including NH4+, NO3-, PO43-, DOC, dissolved oxygen, pH and specific conductivity in the water column were examined in three branches of the same stream. Two of the branches had varying levels of impoundment by beaver and the third had no recent history of beaver alteration. Historically almost every stream system in New England was altered by beaver, but populations reached almost extinction levels with hunting by early settlers. After reintroduction and elimination of natural predators, the populations are again growing, and their effects on ecosystems are coming under question. Studies have shown that beavers alter their local environment by facilitating a shift of nutrient storage from upland forest to the sediments of a pond by altering the entire ecosystems hydrologic regime. In some cases there are no differences between nutrient levels entering and exiting a pond system, but many studies have shown that beaver ponds facilitate nutrient transformations, sequester NO3- and PO43- and increase exports of NH4+ and DOC to downstream systems. Although wetland systems are generally thought to be beneficial to downstream ecosystems, it is not known to what extent beaver activities alter downstream nutrient levels. Preliminary analysis of temporal trends in nutrient concentrations show an overall increase in NO3- from the beginning of June to the end of August in Underhill Brook. There were no significant changes in DOC, little change in PO43- levels, and either no change or a decrease in specific conductivity. Between-branch comparisons showed that the least change took place in the branch unaltered by beaver, and the greatest in the branch with the most area altered by beaver. Nutrient gradients

  4. Collaborating with beaver: An affordable, process-based approach to stream restoration

    NASA Astrophysics Data System (ADS)

    Pollock, M. M.; Jordan, C.; Bouwes, N. W.; Volk, C.; Tattam, I.

    2009-12-01

    We review the initial results of a long-term restoration and monitoring project to restore the lower 32 km of Bridge Creek, an incised and degraded tributary to the John Day River in eastern Oregon, USA. The goal of the project is to cause a detectable population-level benefit to the anadromous steelhead trout (Oncorhynchus mykiss) that use this system. The project takes a process-based restoration approach that involves installing a series of beaver dam support structures designed to mimic beaver dams and to assist beaver (Castor canadensis) in the construction of stable dams. Currently beaver are active in the system, but the lack of structure in the incised stream trench prevents them from establishing dams that last more than one or two years. The lack of stream sinuosity and lack of access to a floodplain concentrates flow forces within the confined incision trench and the dams are regularly breached during high flows in spring or summer. A major goal of this project is to have the beaver do the bulk of the restoration work while we facilitate establishing stable beaver colonies in this degraded stream system such that the small population can expand. As such, the project is not an “engineered” approach to stream restoration with a spatially fixed outcome. Providing some short term assistance to set in motion natural processes by which the stream restores its natural dynamics is the expected outcome. Initial results suggest that increasing the number of beaver dams facilitate stream geomorphic changes that include sediment retention, stream bed aggradation, increased stream sinuosity, pool formation, increased stream length, reduced stream slope, reduced bed shear stress and a shift in the bed composition from cobble towards gravel. The beaver dams also raise water tables in the alluvial aquifer, expand the riparian forest and reduce stream temperatures. Beaver Dam Support Structure colonized by beaver shortly after installation. A plunge pool has formed

  5. A Model of Beaver Meadow Complex Evolution in the Silvies River Basin, Oregon.

    NASA Astrophysics Data System (ADS)

    Nash, C.; Grant, G.; Campbell, S. D.

    2014-12-01

    There is increasing evidence to suggest that the pervasive incision seen in the American West is due, in part, to the removal of beaver (Castor canadensis) in the first half of the 19th century. New restoration strategies for these systems focus on the reintroduction of beaver and construction of beaver dam analogs. Such dams locally raise streams beds and water tables, reconnect incised channels to their former floodplains, trap sediment, increase hydraulic diversity, and promote riparian vegetation. However, the geomorphic and hydrologic impacts of both the original beaver dams and their analogs are poorly understood. Observations in the Silvies River basin in Oregon, USA - an upland, semi-arid catchment with extremely high historic beaver populations and a presently recovering population, inform a conceptual model for valley floor evolution with beaver dams. The evolution of the beaver dam complex is characterized by eight stages of morphologic adjustment: water impoundment, sediment deposition, pond filling, multi-thread meadow creation, dam breaching, channel incision, channel widening, and floodplain development. Well-constructed beaver dams, given sufficient time and sediment flux, will evolve from a series of ponds to a multi-threaded channel flowing through a wet meadow complex. If a dam in the system fails, due to overtopping, undercutting, lack of maintenance, or abandonment, the upstream channel will concentrate into a single channel and incise, followed over time by widening once critical bank heights are exceeded. From stratigraphic, dendrochronologic, and geomorphic measurements, we are constraining average timescales associated with each stage's duration and transitional period. Measured sedimentation rates behind modern beaver dam analogs on five stream systems permit calculation of sediment flux over recent time periods, and aid in developing regional rates of sediment deposition over a range of drainage areas and gradients. Stratigraphic and

  6. Do beaver dams reduce habitat connectivity and salmon productivity in expansive river floodplains?

    PubMed Central

    Kuzishchin, Kirill V.; Stanford, Jack A.

    2016-01-01

    Beaver have expanded in their native habitats throughout the northern hemisphere in recent decades following reductions in trapping and reintroduction efforts. Beaver have the potential to strongly influence salmon populations in the side channels of large alluvial rivers by building dams that create pond complexes. Pond habitat may improve salmon productivity or the presence of dams may reduce productivity if dams limit habitat connectivity and inhibit fish passage. Our intent in this paper is to contrast the habitat use and production of juvenile salmon on expansive floodplains of two geomorphically similar salmon rivers: the Kol River in Kamchatka, Russia (no beavers) and the Kwethluk River in Alaska (abundant beavers), and thereby provide a case study on how beavers may influence salmonids in large floodplain rivers. We examined important rearing habitats in each floodplain, including springbrooks, beaver ponds, beaver-influenced springbrooks, and shallow shorelines of the river channel. Juvenile coho salmon dominated fish assemblages in all habitats in both rivers but other species were present. Salmon density was similar in all habitat types in the Kol, but in the Kwethluk coho and Chinook densities were 3–12× lower in mid- and late-successional beaver ponds than in springbrook and main channel habitats. In the Kol, coho condition (length: weight ratios) was similar among habitats, but Chinook condition was highest in orthofluvial springbrooks. In the Kwethluk, Chinook condition was similar among habitats, but coho condition was lowest in main channel versus other habitats (0.89 vs. 0.99–1.10). Densities of juvenile salmon were extremely low in beaver ponds located behind numerous dams in the orthofluvial zone of the Kwethluk River floodplain, whereas juvenile salmon were abundant in habitats throughout the entire floodplain in the Kol River. If beavers were not present on the Kwethluk, floodplain habitats would be fully interconnected and theoretically

  7. Do beaver dams reduce habitat connectivity and salmon productivity in expansive river floodplains?

    PubMed

    Malison, Rachel L; Kuzishchin, Kirill V; Stanford, Jack A

    2016-01-01

    Beaver have expanded in their native habitats throughout the northern hemisphere in recent decades following reductions in trapping and reintroduction efforts. Beaver have the potential to strongly influence salmon populations in the side channels of large alluvial rivers by building dams that create pond complexes. Pond habitat may improve salmon productivity or the presence of dams may reduce productivity if dams limit habitat connectivity and inhibit fish passage. Our intent in this paper is to contrast the habitat use and production of juvenile salmon on expansive floodplains of two geomorphically similar salmon rivers: the Kol River in Kamchatka, Russia (no beavers) and the Kwethluk River in Alaska (abundant beavers), and thereby provide a case study on how beavers may influence salmonids in large floodplain rivers. We examined important rearing habitats in each floodplain, including springbrooks, beaver ponds, beaver-influenced springbrooks, and shallow shorelines of the river channel. Juvenile coho salmon dominated fish assemblages in all habitats in both rivers but other species were present. Salmon density was similar in all habitat types in the Kol, but in the Kwethluk coho and Chinook densities were 3-12× lower in mid- and late-successional beaver ponds than in springbrook and main channel habitats. In the Kol, coho condition (length: weight ratios) was similar among habitats, but Chinook condition was highest in orthofluvial springbrooks. In the Kwethluk, Chinook condition was similar among habitats, but coho condition was lowest in main channel versus other habitats (0.89 vs. 0.99-1.10). Densities of juvenile salmon were extremely low in beaver ponds located behind numerous dams in the orthofluvial zone of the Kwethluk River floodplain, whereas juvenile salmon were abundant in habitats throughout the entire floodplain in the Kol River. If beavers were not present on the Kwethluk, floodplain habitats would be fully interconnected and theoretically

  8. Food processing by animals: do beavers leach tree bark to improve palatability?

    PubMed

    Müller-Schwarze, D; Brashear, H; Kinnel, R; Hintz, K A; Lioubomirov, A; Skibo, C

    2001-05-01

    Beavers store and consume tree parts in the bodies of water where they live. We examined whether such soaking renders food more palatable by leaching out undesirable compounds. In experiment 1, saplings of red maple, Acer rubrum (RM), were first soaked in a pond for periods of 2, 18, and 36 days, then offered to free-ranging beavers. Soaking for two days rendered RM slightly more acceptable to beavers. To further examine the time window around two days, RM sticks were soaked in distilled water in the laboratory for 1, 2, 4, and 6 days before presenting them to beavers (experiment 2). In experiment 3, twigs of three species were placed on land. Beavers placed RM in the water for 1 to 3 days before consuming the twigs. In experiment 4, sticks were provided in the water at Cranberry Lake Biological Station (CLBS). Most quaking aspen (QA) was consumed during the first night, and most witch hazel, Hamamelis virginiana (WH), during the third night. At Allegany State Park (ASP), no such difference was found. Twigs were provided in the water in experiment 5. At ASP, WH was taken after three days in the water, and at CLBS little WH was consumed, and only during the third night. A meta-analysis of all experiments shows that relatively more WH is consumed after two days than any other species. Experiment 6 traced the time beavers left their own harvested branches in the water. Unlike other tree species, WH remained in the water for two to four days before being consumed. Experiment 7 measured the phenolics leached into water from RM twigs and small pieces of bark soaked for 10 and 8 days, respectively. Shredded bark lost 50-60% of leachable phenolics into the water, and twigs 70-80%. We conclude that beavers can use water to leach undesirable compounds from their food. Although this effect was not robust, our study is the first of its kind.

  9. Trends in Rocky Mountain amphibians and the role of beaver as a keystone species

    USGS Publications Warehouse

    Hossack, Blake R.; Gould, William R.; Patla, Debra A.; Muths, Erin L.; Daley, Rob; Legg, Kristin; Corn, P. Stephen

    2015-01-01

    Despite prevalent awareness of global amphibian declines, there is still little information on trends for many widespread species. To inform land managers of trends on protected landscapes and identify potential conservation strategies, we collected occurrence data for five wetland-breeding amphibian species in four national parks in the U.S. Rocky Mountains during 2002–2011. We used explicit dynamics models to estimate variation in annual occupancy, extinction, and colonization of wetlands according to summer drought and several biophysical characteristics (e.g., wetland size, elevation), including the influence of North American beaver (Castor canadensis). We found more declines in occupancy than increases, especially in Yellowstone and Grand Teton national parks (NP), where three of four species declined since 2002. However, most species in Rocky Mountain NP were too rare to include in our analysis, which likely reflects significant historical declines. Although beaver were uncommon, their creation or modification of wetlands was associated with higher colonization rates for 4 of 5 amphibian species, producing a 34% increase in occupancy in beaver-influenced wetlands compared to wetlands without beaver influence. Also, colonization rates and occupancy of boreal toads (Anaxyrus boreas) and Columbia spotted frogs (Rana luteiventris) were ⩾2 times higher in beaver-influenced wetlands. These strong relationships suggest management for beaver that fosters amphibian recovery could counter declines in some areas. Our data reinforce reports of widespread declines of formerly and currently common species, even in areas assumed to be protected from most forms of human disturbance, and demonstrate the close ecological association between beaver and wetland-dependent species.

  10. Ecosystem engineering by invasive exotic beavers reduces in-stream diversity and enhances ecosystem function in Cape Horn, Chile.

    PubMed

    Anderson, Christopher B; Rosemond, Amy D

    2007-11-01

    Species invasions are of global significance, but predicting their impacts can be difficult. Introduced ecosystem engineers, however, provide an opportunity to test the underlying mechanisms that may be common to all invasive engineers and link relationships between changes in diversity and ecosystem function, thereby providing explanatory power for observed ecological patterns. Here we test specific predictions for an invasive ecosystem engineer by quantifying the impacts of habitat and resource modifications caused by North American beavers (Castor canadensis) on aquatic macroinvertebrate community structure and stream ecosystem function in the Cape Horn Biosphere Reserve, Chile. We compared responses to beavers in three habitat types: (1) forested (unimpacted) stream reaches, (2) beaver ponds, and (3) sites immediately downstream of beaver dams in four streams. We found that beaver engineering in ponds created taxonomically simplified, but more productive, benthic macroinvertebrate assemblages. Specifically, macroinvertebrate richness, diversity and number of functional feeding groups were reduced by half, while abundance, biomass and secondary production increased three- to fivefold in beaver ponds compared to forested sites. Reaches downstream of beaver ponds were very similar to natural forested sections. Beaver invasion effects on both community and ecosystem parameters occurred predominantly via increased retention of fine particulate organic matter, which was associated with reduced macroinvertebrate richness and diversity (via homogenization of benthic microhabitat) and increased macroinvertebrate biomass and production (via greater food availability). Beaver modifications to macroinvertebrate community structure were largely confined to ponds, but increased benthic production in beaver-modified habitats adds to energy retention and flow for the entire stream ecosystem. Furthermore, the effects of beavers on taxa richness (negative) and measures of

  11. Influence of Beaver-Induced Complexity on Storage of Organic Carbon and Sediment in Colorado Mountain Streams

    NASA Astrophysics Data System (ADS)

    Laurel, D.; Wohl, E.

    2016-12-01

    Beaver meadows (complexes of multiple different aged beaver dams and ponds) influence the storage of water, sediment, and nutrients. Although beaver meadows compose only a small fraction of catchment area, they provide a potentially large role in retaining these fluxes in mountain watersheds. Multiple dams and ponds in beaver meadows increase overbank flows leading to an anastomosing stream channel planform, and deposition of fine sediment along with particulate organic carbon. An earlier study estimated a range of cumulative carbon stored in 27 beaver meadows east of the continental divide in Rocky Mountain National Park. Storage ranged from 735,800 to 2.8 x 106 Mg carbon, with the high value estimating storage if all the meadows had active beaver (historic conditions pre-European settlement) and the lower value estimating current conditions where many of the meadows are abandoned. We combined geomorphic surveys, soil depth probing by rebar, and soil cores analyzed for carbon content to investigate the influence of beaver activity, meadow size, and meadow placement within the drainage on catchment-scale fluxes of fine sediment and organic carbon. We found carbon storage in floodplain soils to be highly variable across both active and abandoned meadows; however, active beaver meadows store more carbon on average than abandoned meadows. In addition, active meadows with high levels of beaver activity (multiple colonies) stored greater volumes of fine sediment behind dams and in ponds. These results have implications for the restoration potential of abandoned beaver meadows in mountain environments to store greater volumes of sediment and more organic carbon if beaver are successfully reintroduced.

  12. Unusual fatty acids in the depot fat of the Canadian beaver (Castor canadensis).

    PubMed

    Käkelä, R; Hyvärinen, H; Vainiotalo, P

    1996-03-01

    Unusual fatty acids in the adipose tissue of the Canadian beaver were analysed by argentation thin-layer chromatography, gas-liquid chromatography and gas chromatography-mass spectrometry of several adducts and spectroscopic measurements. The total proportion of trans-octadecenoic fatty acids and the distribution of double bonds in these acids resembled those of ruminant fats. Because trans-11-18:1 was the main trans-18:1 isomer of beaver fat and a conjugated diene cis-9, trans-11-18:2 was also detected, it can be deduced that linoleic acid (cis-9, cis-12-18:2) is biohydrogenated in the beaver. The ideas that microbial processes intervene before normal absorption and fatty acid metabolism of the beaver is also supported by the larger amounts of anteiso odd-chain fatty acids with respect to the corresponding iso acids in the beaver depots. In addition, the distribution of double bonds in the cis-octadecenoic acids was wide, as it is in the depot fats of ruminants.

  13. Histological Evaluation of Selected Organs of the Eurasian Beavers (Castor fiber) Inhabiting Poland.

    PubMed

    Dolka, I; Giżejewska, A; Giżejewski, Z; Kluciński, W; Kołodziejska, J

    2015-10-01

    There is a general scarcity of data on the histological structure of major organs in the Eurasian beaver (Castor fiber). This study presents the histological characteristics of beaver organs such as the liver, spleen, cardiac muscle, lungs and kidneys. Tissue samples were collected from 21 beavers and analysed. Selected samples of tail tissue were additionally examined. Tissue samples were placed in neutral buffered formalin and embedded in paraffin. 4-μm-thick sections were stained with haematoxylin and eosin, and other staining techniques were also used. Scant amounts of inter-lobular connective tissue were found in the liver. Ion or copper deposition was not observed, but scattered cytoplasmic glycogen deposits were present in hepatocytes. Our results suggest that beavers have defensive rather than storage spleens. Interestingly, the presence of melanin in splenic red pulp was noted. The histological structure of the examined organs closely resembled that of other rodent species. According to our knowledge, this is the first study evaluating the histological structure of beaver organs. Nevertheless, precise characterization of the evaluated organs requires further work with the involvement of accurate and reliable techniques, such as molecular biology or electron microscopy methods.

  14. Do Eurasian beavers smear their pelage with castoreum and anal gland secretion?

    PubMed

    Rosell, Frank

    2002-08-01

    The scent-matching hypothesis postulates that scent marks provide an olfactory link between a resident owner and his territory, and that this enables intruding animals to recognize the chance of escalated conflicts. However, it is unclear if Eurasian beavers (Castor fiber) mark their own pelage with castoreum from their castor sacs (i.e., the same material used in territorial marking); and/or if beavers mark their pelage with anal gland secretion (AGS) from the anal glands to waterproof the pelage and to act as a "living-scent mark." Chemical analysis (gas chromatography and mass spectrometry) of hair samples from 22 live-trapped beavers revealed that castoreum compounds were not present in any samples, AGS compounds were found from 3 animals (13.6%) around the cloaca, and the compound squalene was found in all the samples. Beavers may release castoreum directly into the water when it meets an intruder. Thereby, the "scent mark" in the water can provide an olfactory link between a resident owner and his territory. Squalene, in contrast to AGS, may be essential for keeping beaver pelts water-repellant.

  15. Beaver ponds increase methylmercury concentrations in Canadian shield streams along vegetation and pond-age gradients.

    PubMed

    Roy, Virginie; Amyot, Marc; Carignan, Richard

    2009-08-01

    Beaver impoundments flood forested areas and may be important production sites for methylmercury (MeHg) because of the resulting enhanced microbial activity and oxygen depletion. The influence of 17 beaver impoundments on streamwater chemistry (total mercury (THg), MeHg, nutrients, cations, and anions)] was investigated by sampling sites located along vegetation and pond-age gradients in southwestern Quebec (Canada). Recently inundated beaver ponds (< 10 years old) and those located in coniferous watersheds had the highest MeHg concentrations (range, 0.10-4.53 ng L(-1)) and greatest methylation efficiencies (% THg as MeHg; range, 10-74%). High heterotrophic activity likely occurred in the beaver ponds as suggested by depletions of dissolved oxygen, sulfate and nitrite-nitrate concentrations, and increases in nutrients (e.g., dissolved organic carbon, total phosphorus, and total nitrogen) in outlets compared to inlets. Acidic waters at coniferous sites may have stimulated more MeHg production than in mixed woodland regions. Lower methylation efficiencies in older ponds (> 20 years old) may be due to the degradation of less labile organic matter as ponds age. Beavers actively alter watersheds by building impoundments, and our findings indicate that this landscape disturbance may be a significant source of MeHg to downstream water bodies.

  16. Geology of the central Mineral Mountains, Beaver County, Utah

    SciTech Connect

    Sibbett, B.S.; Nielson, D.L.

    1980-03-01

    The Mineral Mountains are located in Beaver and Millard Counties, southwestern Utah. The range is a horst located in the transition zone between the Basin and Range and Colorado Plateau geologic provinces. A multiple-phase Tertiary pluton forms most of the range, with Paleozoic rocks exposed on the north and south and Precambrian metamorphic rocks on the west in the Roosevelt Hot Springs KGRA (Known Geothermal Resource Area). Precambrian banded gneiss and Cambrian carbonate rocks have been intruded by foliated granodioritic to monzonitic rocks of uncertain age. The Tertiary pluton consists of six major phases of quartz monzonitic to leucocratic granitic rocks, two diorite stocks, and several more mafic units that form dikes. During uplift of the mountain block, overlying rocks and the upper part of the pluton were partially removed by denudation faulting to the west. The interplay of these low-angle faults and younger northerly trending Basin and Range faults is responsible for the structural control of the Roosevelt Hot Springs geothermal system. The structural complexity of the Roosevelt Hot Springs KGRA is unique within the range, although the same tectonic style continues throughout the range. During the Quaternary, rhyolite volcanism was active in the central part of the range and basaltic volcanism occurred in the northern portion of the map area. The heat source for the geothermal system is probably related to the Quaternary rhyolite volcanic activity.

  17. Bioactivity of beaver castoreum constituents using principal components analysis.

    PubMed

    Schulte, B A; Müller-Schwarze, D; Tang, R; Webster, F X

    1995-07-01

    North American beaver (Castor canadensis) were observed to sniff from the water and make land visits to some synthetic chemical components of castoreum placed on experimental scent mounds (ESM). In previous analysis, the elicitation (presence/absence), completeness, and/or strength (number, duration) of these key responses served as separate measures of biological activity. In this paper, we used principal components analysis (PCA) to combine linearly six related measures of observed response and one index of overnight visitation calculated over all trials. The first principal component accounted for a majority of the variation and allowed ranking of the samples based on their composite bioactivity. A second PCA, based only on response trials (excluding trials with no responses), showed that responses to the synthetic samples, once elicited, did not vary greatly in completeness or strength. None of the samples evoked responses as complete or strong as the castoreum control. Castoreum also elicited more multiple land visits (repeated visits to the ESM by the same individual or by more than one family member) than the synthetic samples, indicating that an understanding of the castoreum chemosignal requires consideration of responses by the family unit, and not just the land visit by the initial responder.

  18. Economics of Beaver-Herter extraction process revealed

    SciTech Connect

    Not Available

    1986-09-01

    The Herter process is a surface-mined solvent extraction process which utilizes fatty acids as the solvent. The uniqueness of the Herter process if that it provides a low energy method of separating the fatty acids from the recovered oil for subsequent recycling. The Herter process recovers the fatty acid by saponification, followed by migration of the soap to the aqueous phase, and then desaponification of the resulting soap phase again followed by phase separation. The formation of a hydrocarbon-soap-water emulsion limits the process unless carefully controlled by the addition of an alcohol cosolvent. Addition of the short-chain alcohol limits emulsification and allows a meaningful separation to be accomplished. The modified process is known as the Beaver-Herter process. A bench-scale model of the process has recently been completed and has demonstrated the technical feasibility of the process. A computer model has been designed to evaluate the economic feasibility of the process on a site specific basis. This paper summarizes the process, the site selection (Oklahoma), and the economic analysis.

  19. Mapping wetlands on beaver flowages with 35-mm photography

    USGS Publications Warehouse

    Kirby, R.E.

    1976-01-01

    Beaver flowages and associated wetlands on the Chippewa National Forest, north-central Minnesota, were photographed from the ground and from the open side window of a small high-wing monoplane. The 35-mm High Speed Ektachrome transparencies obtained were used to map the cover-type associations visible on the aerial photographs. Nearly vertical aerial photos were rectified by projecting the slides onto a base map consisting ofcontrol points located by plane-table survey. Maps were prepared by tracing the recognizable stands of vegetation in the rectified projection at the desired map scale. Final map scales ranging from 1:260 to 1:571 permitted identification and mapping of 26 cover-type associations on 10 study flowages in 1971. This cover-mapping technique was economical and substituted for detailed ground surveys. Comparative data from 10 flowages were collected serially throughout the entire open-water season. Although developed for analysis of waterfowl habitat, the technique has application to other areas of wildlife management and ecological investigation.

  20. Characterization of the North American beaver (Castor canadensis) papillomavirus genome.

    PubMed

    Rogovskyy, Artem S; Chen, Zigui; Burk, Robert D; Bankhead, Troy

    2014-01-10

    The papillomaviruses comprise a large group of viruses that cause proliferations of the stratified squamous epithelium of skin and mucosa in a variety of animals. An earlier report identified a novel papillomavirus of the North American beaver, Castor canadensis (CcanPV1) that was associated with cutaneous exophytic lesions. In the current study, we determined the sequence of the complete 7435 basepair genome of CcanPV1. The genome contains an Upstream Regulatory Region located between the end of L1 and the start of E6, and seven canonical papillomavirus open reading frames encoding five early (E6, E7, E1, E2, and E4) and two late (L2 and L1) proteins. No E5 open reading frame was detected. Phylogenetic analysis of the CcanPV1 genome places the virus between the genera Kappapapillomavirus and Mupapillomavirus. Analyses of the papillomavirus genomes detected in different species of the order Rodentia indicate these viruses do not form a monophyletic clade. Copyright © 2013 Elsevier B.V. All rights reserved.

  1. Ground-water data: Beaver, Escalante, Cedar City, and Parowan Valleys; parts of Washington, Iron, Beaver, and Millard Counties, Utah

    USGS Publications Warehouse

    Sandberg, George W.

    1963-01-01

    This report is intended to serve two purposes: (1) to make available to the public basic ground-water data useful in planning and studying development of water resources, and (2) to supplement an interpretive report that will be published later.Records were collected during the period 1935-62 by the U.S. Geological Survey in cooperation with the Utah State Engineer as part of the investigation of ground-water conditions in the Beaver, Escalante, Cedar City, and Parowan Walleys. This report will include records collected subsequent to data published in earlier reports listed in the bibliography. The interpretive material will be published in a companion report by George W. Sandberg.This report is most useful in predicting conditions likely to be found in areas that are being considered as well sites. The person considering the new well can spot the proposed site on plate 1 and examine the records of nearby wells as shown in the tables and figure 2. From table 1 he can note such things as diameter, depth, water level, yield, use of water, and depth to aquifers in wells in the vicinity, and from the well logs in table 3 he can note the type of material that yields water to the wells. Table 2 gives several years record of yields and pumping levels of irrigation wells, and in table 4 are the chemical analyses of water from wells and springs. Figure 2 shows the historic fluctuations and trends of water levels in the four valleys. If the reader decides from his examination that conditions are favorable, he can place an application to drill a well with the State Engineer. During the past several years, however, the State Engineer has rejected new applications to appropriate water in major portions of Beaver Valley, Milford and Beryl-Enterprise districts in Escalante Valley, and Cedar City Valley. Anyone seeking to initiate a new ground-water right in any of these areas should obtain information from the State Engineer's Office in either Salt Lake City or Cedar City to

  2. 78 FR 41805 - In the Matter of FirstEnergy Nuclear Operating Company; Beaver Valley Power Station; Independent...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-11

    ... COMMISSION In the Matter of FirstEnergy Nuclear Operating Company; Beaver Valley Power Station; Independent... fingerprinting for unescorted access to FirstEnergy Nuclear Operating Company. FOR FURTHER INFORMATION CONTACT: L..., the NRC is providing notice in the matter of FirstEnergy Nuclear Operating Company, Beaver Valley...

  3. Development of a reliable method for determining sex for a primitive rodent, the Point Arena mountain beaver (Aplodontia rufa nigra)

    Treesearch

    Kristine L. Pilgrim; William J. Zielinski; Fredrick V. Schlexer; Michael K. Schwartz

    2012-01-01

    The mountain beaver (Aplodontia rufa) is a primitive species of rodent, often considered a living fossil. The Point Arena mountain beaver (Aplodontia rufa nigra) is an endangered subspecies that occurs in a very restricted range in northern California. Efforts to recover this taxon have been limited by the lack of knowledge on their demography, particularly sex and age...

  4. 77 FR 71189 - AES Beaver Valley, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-29

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission AES Beaver Valley, LLC; Supplemental Notice That Initial Market- Based Rate...-referenced proceeding, of AES Beaver Valley, LLC's application for market-based rate authority, with...

  5. Beaver dams and overbank floods influence groundwater-surface water interactions of a Rocky Mountain riparian area

    USGS Publications Warehouse

    Westbrook, C.J.; Cooper, D.J.; Baker, B.W.

    2006-01-01

    Overbank flooding is recognized by hydrologists as a key process that drives hydrogeomorphic and ecological dynamics in mountain valleys. Beaver create dams that some ecologists have assumed may also drive riparian hydrologic processes, but empirical evidence is lacking. We examined the influence of two in-channel beaver dams and a 10 year flood event on surface inundation, groundwater levels, and flow patterns in a broad alluvial valley during the summers of 2002-2005. We studied a 1.5 km reach of the fourth-order Colorado River in Rocky Mountain National Park (RMNP), Colorado, USA. The beaver dams and ponds greatly enhanced the depth, extent, and duration of, inundation associated with floods; they also elevate the water table during both high and low flows. Unlike previous studies we found the main effects of beaver on hydrologic processes occurred downstream of the dam rather than being confined to the near-pond area. Beaver dams on the Colorado River caused river water to move around them as surface runoff and groundwater seepage during both high- and low-flow periods. The beaver dams attenuated the expected water table decline in the drier summer months for 9 and 12 ha of the 58 ha study area. Thus we provide empirical evidence that beaver can influence hydrologic processes during the peak flow and low-flow periods on some streams, suggesting that beaver can create and maintain hydrologic regimes suitable for the formation and persistence of wetlands. Copyright 2006 by the American Geophysical Union.

  6. Coupled stream and population dynamics: Modeling the role beaver (Castor canadensis) play in generating juvenile steelhead (Oncorhynchus mykiss) habitat

    NASA Astrophysics Data System (ADS)

    Jordan, C.; Bouwes, N.; Wheaton, J. M.; Pollock, M.

    2013-12-01

    Over the past several centuries, the population of North American Beaver has been dramatically reduced through fur trapping. As a result, the geomorphic impacts long-term beaver occupancy and activity can have on fluvial systems have been lost, both from the landscape and from our collective memory such that physical and biological models of floodplain system function neither consider nor have the capacity to incorporate the role beaver can play in structuring the dynamics of streams. Concomitant with the decline in beaver populations was an increasing pressure on streams and floodplains through human activity, placing numerous species of stream rearing fishes in peril, most notably the ESA listing of trout and salmon populations across the entirety of the Western US. The rehabilitation of stream systems is seen as one of the primary means by which population and ecosystem recovery can be achieved, yet the methods of stream rehabilitation are applied almost exclusively with the expected outcome of a static idealized stream planform, occasionally with an acknowledgement of restoring processes rather than form and only rarely with the goal of a beaver dominated riverscape. We have constructed an individual based model of trout and beaver populations that allows the exploration of fish population dynamics as a function of stream habitat quality and quantity. We based the simulation tool on Bridge Creek (John Day River basin, Oregon) where we have implemented a large-scale restoration experiment using wooden posts to provide beavers with stable platforms for dam building and to simulate the dams themselves. Extensive monitoring captured geomorphic and riparian changes, as well as fish and beaver population responses; information we use to parameterize the model as to the geomorphic and fish response to dam building beavers. In the simulation environment, stream habitat quality and quantity can be manipulated directly through rehabilitation actions and indirectly

  7. Assessment of a new Bacteroidales marker targeting North American beaver (Castor canadensis) fecal pollution by real-time PCR.

    PubMed

    Marti, Romain; Zhang, Yun; Tien, Yuan-Ching; Lapen, David R; Topp, Edward

    2013-11-01

    In many settings wildlife can be a significant source of fecal pathogen input into surface water. The North American beaver (Castor canadensis) is a zoonotic reservoir for several human pathogens including Cryptosporidium spp. and Giardia spp. In order to specifically detect fecal pollution by beavers, we have developed and validated a beaver-specific Bacteroidales marker, designated Beapol01, based on the 16S rRNA gene. The marker is suitable for quantifying pollution using real-time PCR. The specificity and sensitivity of the marker was excellent, Beaver signal was detected in water of a mixed-activity watershed harbouring this rodent. Overall, Beapol01 will be useful for a better understanding of fecal source inputs in drainage basins inhabited by the beaver. © 2013.

  8. Impact of beaver dams on abundance and distribution of anadromous salmonids in two lowland streams in Lithuania.

    PubMed

    Virbickas, Tomas; Stakėnas, Saulius; Steponėnas, Andrius

    2015-01-01

    European beaver dams impeded movements of anadromous salmonids as it was established by fishing survey, fish tagging and redd counts in two lowland streams in Lithuania. Significant differences in abundancies of other litophilic fish species and evenness of representation by species in the community were detected upstream and downstream of the beaver dams. Sea trout parr marked with RFID tags passed through several successive beaver dams in upstream direction, but no tagged fish were detected above the uppermost dam. Increase in abundances of salmonid parr in the stream between the beaver dams and decrease below the dams were recorded in November, at the time of spawning of Atlantic salmon and sea trout, but no significant changes were detected in the sections upstream of the dams. After construction of several additional beaver dams in the downstream sections of the studied streams, abundance of Atlantic salmon parr downstream of the dams decreased considerably in comparison with that estimated before construction.

  9. Impact of Beaver Dams on Abundance and Distribution of Anadromous Salmonids in Two Lowland Streams in Lithuania

    PubMed Central

    Virbickas, Tomas; Stakėnas, Saulius; Steponėnas, Andrius

    2015-01-01

    European beaver dams impeded movements of anadromous salmonids as it was established by fishing survey, fish tagging and redd counts in two lowland streams in Lithuania. Significant differences in abundancies of other litophilic fish species and evenness of representation by species in the community were detected upstream and downstream of the beaver dams. Sea trout parr marked with RFID tags passed through several successive beaver dams in upstream direction, but no tagged fish were detected above the uppermost dam. Increase in abundances of salmonid parr in the stream between the beaver dams and decrease below the dams were recorded in November, at the time of spawning of Atlantic salmon and sea trout, but no significant changes were detected in the sections upstream of the dams. After construction of several additional beaver dams in the downstream sections of the studied streams, abundance of Atlantic salmon parr downstream of the dams decreased considerably in comparison with that estimated before construction. PMID:25856377

  10. Ecosystem experiment reveals benefits of natural and simulated beaver dams to a threatened population of steelhead (Oncorhynchus mykiss)

    PubMed Central

    Bouwes, Nicolaas; Weber, Nicholas; Jordan, Chris E.; Saunders, W. Carl; Tattam, Ian A.; Volk, Carol; Wheaton, Joseph M.; Pollock, Michael M.

    2016-01-01

    Beaver have been referred to as ecosystem engineers because of the large impacts their dam building activities have on the landscape; however, the benefits they may provide to fluvial fish species has been debated. We conducted a watershed-scale experiment to test how increasing beaver dam and colony persistence in a highly degraded incised stream affects the freshwater production of steelhead (Oncorhynchus mykiss). Following the installation of beaver dam analogs (BDAs), we observed significant increases in the density, survival, and production of juvenile steelhead without impacting upstream and downstream migrations. The steelhead response occurred as the quantity and complexity of their habitat increased. This study is the first large-scale experiment to quantify the benefits of beavers and BDAs to a fish population and its habitat. Beaver mediated restoration may be a viable and efficient strategy to recover ecosystem function of previously incised streams and to increase the production of imperiled fish populations. PMID:27373190

  11. Flood of August 27-28, 1977, West Cache Creek and Blue Beaver Creek, southwestern Oklahoma

    USGS Publications Warehouse

    Corley, Robert K.; Huntzinger, Thomas L.

    1979-01-01

    This report documents a major storm which occurred August 27-28, 1977, in southwest Oklahoma near the communities of Cache and Faxon, OK. Blue Beaver Creek and West Cache Creek and their tributaries experienced extensive flooding that caused an estimated $1 million in damages. Reported rainfall amounts of 8 to 12 inches in 6 hours indicate the storm had a frequency in excess of the 100-year rainfall. Peak discharges on Blue Beaver Creek near Cache and West Cache Creek near Faxon were 13,500 cubic feet per second and 45,700 cubic feet per second respectively. The estimated flood frequency was in excess of 100 years on Blue Beaver Creek and in excess of 50 years on West Cache Creek. Unit runoff on small basins were in excess of 2000 cubic feet per second per square mile. Surveyed highwater marks were used to map the flooded area. (USGS)

  12. Sedimentation rates and patterns in beaver ponds in a mountain environment

    NASA Astrophysics Data System (ADS)

    Butler, David R.; Malanson, George P.

    1995-09-01

    Sediment depth was measured at several sites within each of eight beaver ponds in Glacier National Park, Montana, and sediment samples wen; collected from five of these ponds. Accumulation rates of sediments far exceeded published rates from boreal forest landscapes in eastem and central North America. Pond area strongly predicts volume of sedimentation. Textural differences illustrated spatial variations associated with position in a pond and along a pond sequence. Organic matter content was significantly higher in older ponds, and has ramifications for the development of the benthos and the long-term storage of matter in ponds. The role of beavers as biogeomorphic agents is profound, but requires further elucidation to distinguish between fluvial sediment deposition in ponds and sediment deposition associated with beaver excavational activity.

  13. Bacterial and Archaeal Diversity in the Gastrointestinal Tract of the North American Beaver (Castor canadensis)

    PubMed Central

    Gruninger, Robert J.; McAllister, Tim A.; Forster, Robert J.

    2016-01-01

    The North American Beaver (Castor canadensis) is the second largest living rodent and an iconic symbol of Canada. The beaver is a semi-aquatic browser whose diet consists of lignocellulose from a variety of plants. The beaver is a hindgut fermenter and has an enlarged ceacum that houses a complex microbiome. There have been few studies examining the microbial diversity in gastrointestinal tract of hindgut fermenting herbivores. To examine the bacterial and archaeal communities inhabiting the gastrointestinal tract of the beaver, the microbiome of the ceacum and feaces was examined using culture-independent methods. DNA from the microbial community of the ceacum and feaces of 4 adult beavers was extracted, and the16S rRNA gene was sequenced using either bacterial or archaeal specific primers. A total of 1447 and 1435 unique bacterial OTUs were sequenced from the ceacum and feaces, respectively. On average, the majority of OTUs within the ceacum were classified as Bacteroidetes (49.2%) and Firmicutes (47.6%). The feaces was also dominated by OTUs from Bacteroidetes (36.8%) and Firmicutes (58.9%). The composition of bacterial community was not significantly different among animals. The composition of the ceacal and feacal microbiome differed, but this difference is due to changes in the abundance of closely related OTUs, not because of major differences in the taxonomic composition of the communities. Within these communities, known degraders of lignocellulose were identified. In contrast, to the bacterial microbiome, the archaeal community was dominated by a single species of methanogen, Methanosphaera stadtmanae. The data presented here provide the first insight into the microbial community within the hindgut of the beaver. PMID:27227334

  14. Bacterial and Archaeal Diversity in the Gastrointestinal Tract of the North American Beaver (Castor canadensis).

    PubMed

    Gruninger, Robert J; McAllister, Tim A; Forster, Robert J

    2016-01-01

    The North American Beaver (Castor canadensis) is the second largest living rodent and an iconic symbol of Canada. The beaver is a semi-aquatic browser whose diet consists of lignocellulose from a variety of plants. The beaver is a hindgut fermenter and has an enlarged ceacum that houses a complex microbiome. There have been few studies examining the microbial diversity in gastrointestinal tract of hindgut fermenting herbivores. To examine the bacterial and archaeal communities inhabiting the gastrointestinal tract of the beaver, the microbiome of the ceacum and feaces was examined using culture-independent methods. DNA from the microbial community of the ceacum and feaces of 4 adult beavers was extracted, and the16S rRNA gene was sequenced using either bacterial or archaeal specific primers. A total of 1447 and 1435 unique bacterial OTUs were sequenced from the ceacum and feaces, respectively. On average, the majority of OTUs within the ceacum were classified as Bacteroidetes (49.2%) and Firmicutes (47.6%). The feaces was also dominated by OTUs from Bacteroidetes (36.8%) and Firmicutes (58.9%). The composition of bacterial community was not significantly different among animals. The composition of the ceacal and feacal microbiome differed, but this difference is due to changes in the abundance of closely related OTUs, not because of major differences in the taxonomic composition of the communities. Within these communities, known degraders of lignocellulose were identified. In contrast, to the bacterial microbiome, the archaeal community was dominated by a single species of methanogen, Methanosphaera stadtmanae. The data presented here provide the first insight into the microbial community within the hindgut of the beaver.

  15. Oxygen isotopic determination of climatic variation using phosphate from beaver bone, tooth enamel, and dentine

    NASA Astrophysics Data System (ADS)

    Stuart-Williams, Hilary Le Q.; Schwarcz, Henry P.

    1997-06-01

    The δ 18O of Canadian beaver ( Castor canadensis) teeth should reflect variations in the isotopic composition of the water in which the beavers live, as their incisors grow rapidly and continuously. We observe seasonal variations in phosphate δ 18O using samples of enamel taken along the length of single teeth. In the spring the δ 18O of the enamel being deposited gradually declines, reflecting a retarded input of δ 18O depleted winter water. After mid-year, enamel δ 18O is higher than average (as represented by the δ 18O of bone phosphate from the same animal) and passes through a maximum in late summer or early fall. Overall, the amplitude of seasonal excursions in enamel δ 18O (4‰) is much smaller than the expected summer-winter range in the δ 18O of meteoric water (> 10‰). This is because hydrologic mixing processes, gradual admixing of environmental water with beaver body water, long-term plant growth, and oxygen inputs of relatively constant value (particularly atmospheric oxygen) tend to even out summer-winter differences in the δ 18O of oxygen inputs to the beaver. The δ 18O of bone from adult beavers was uniform at 11.9 ± 0.5‰ over the study area. Analyses of a Sangamon age giant beaver ( Castoroides ohioensis) incisor from Hopwood Farm, Illinois, show a slightly larger 5.5‰ seasonal cycle of δ 18O with an average enamel δ 18O of 18‰. This suggests that average temperatures were warmer during the Sangamon than today and that seasonal temperature differences and/or relative humidity variations were larger.

  16. Resurgent beaver ponds in the northeastern United States: implications for greenhouse gas emissions.

    PubMed

    Lazar, Julia G; Addy, Kelly; Welsh, Molly K; Gold, Arthur J; Groffman, Peter M

    2014-11-01

    Beaver ponds, a wetland type of increasing density in the northeastern United States, vary spatially and temporally, creating high uncertainty in their impact to greenhouse gas (GHG) emissions. We used floating static gas chambers to assess diffusive fluxes of methane (CH), carbon dioxide (CO), and nitrous oxide (NO) from the air-water interface of three beaver ponds (0.05-8 ha) in Rhode Island from fall 2012 to summer 2013. Gas flux was based on linear changes of gas concentrations in chambers over 1 h. Our results show that these beaver ponds generated considerable CH and CO emissions. Methane flux (18-556 mg m d) showed no significant seasonal differences, but the shallowest pond generated significantly higher CH flux than the other ponds. Carbon dioxide flux (0.5-22.0 g m d) was not significantly different between sites, but it was significantly higher in the fall, possibly due to the degradation of fresh leaves. Nitrous oxide flux was low (0-2.4 mg m d). Overall, CH and CO comprised most of the global warming potential, 61 and 38%, respectively. The shallowness of the beaver ponds may have limited the time needed for CH oxidation to CO before CH escaped to the atmosphere. Beaver dams also increase the aerial extent of hydric soils, which may transform riparian areas from upland GHG sinks to wetland GHG sources thereby changing the net global warming potential. Further studies tracking the pattern and conditions of beaver pond creation and abandonment will be essential to understanding their role as GHG sources. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  17. Using ecosystem engineers as tools in habitat restoration and rewilding: beaver and wetlands.

    PubMed

    Law, Alan; Gaywood, Martin J; Jones, Kevin C; Ramsay, Paul; Willby, Nigel J

    2017-12-15

    Potential for habitat restoration is increasingly used as an argument for reintroducing ecosystem engineers. Beaver have well known effects on hydromorphology through dam construction, but their scope to restore wetland biodiversity in areas degraded by agriculture is largely inferred. Our study presents the first formal monitoring of a planned beaver-assisted restoration, focussing on changes in vegetation over 12years within an agriculturally-degraded fen following beaver release, based on repeated sampling of fixed plots. Effects are compared to ungrazed exclosures which allowed the wider influence of waterlogging to be separated from disturbance through tree felling and herbivory. After 12years of beaver presence mean plant species richness had increased on average by 46% per plot, whilst the cumulative number of species recorded increased on average by 148%. Heterogeneity, measured by dissimilarity of plot composition, increased on average by 71%. Plants associated with high moisture and light conditions increased significantly in coverage, whereas species indicative of high nitrogen decreased. Areas exposed to both grazing and waterlogging generally showed the most pronounced change in composition, with effects of grazing seemingly additive, but secondary, to those of waterlogging. Our study illustrates that a well-known ecosystem engineer, the beaver, can with time transform agricultural land into a comparatively species-rich and heterogeneous wetland environment, thus meeting common restoration objectives. This offers a passive but innovative solution to the problems of wetland habitat loss that complements the value of beavers for water or sediment storage and flow attenuation. The role of larger herbivores has been significantly overlooked in our understanding of freshwater ecosystem function; the use of such species may yet emerge as the missing ingredient in successful restoration. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights

  18. Beaver-mediated lateral hydrologic connectivity, fluvial carbon and nutrient flux, and aquatic ecosystem metabolism

    NASA Astrophysics Data System (ADS)

    Wegener, Pam; Covino, Tim; Wohl, Ellen

    2017-06-01

    River networks that drain mountain landscapes alternate between narrow and wide valley segments. Within the wide segments, beaver activity can facilitate the development and maintenance of complex, multithread planform. Because the narrow segments have limited ability to retain water, carbon, and nutrients, the wide, multithread segments are likely important locations of retention. We evaluated hydrologic dynamics, nutrient flux, and aquatic ecosystem metabolism along two adjacent segments of a river network in the Rocky Mountains, Colorado: (1) a wide, multithread segment with beaver activity; and, (2) an adjacent (directly upstream) narrow, single-thread segment without beaver activity. We used a mass balance approach to determine the water, carbon, and nutrient source-sink behavior of each river segment across a range of flows. While the single-thread segment was consistently a source of water, carbon, and nitrogen, the beaver impacted multithread segment exhibited variable source-sink dynamics as a function of flow. Specifically, the multithread segment was a sink for water, carbon, and nutrients during high flows, and subsequently became a source as flows decreased. Shifts in river-floodplain hydrologic connectivity across flows related to higher and more variable aquatic ecosystem metabolism rates along the multithread relative to the single-thread segment. Our data suggest that beaver activity in wide valleys can create a physically complex hydrologic environment that can enhance hydrologic and biogeochemical buffering, and promote high rates of aquatic ecosystem metabolism. Given the widespread removal of beaver, determining the cumulative effects of these changes is a critical next step in restoring function in altered river networks.

  19. Wood-Beaver modification improves fatty acid process for tar sands

    SciTech Connect

    Not Available

    1987-03-01

    The original Herter process uses fatty acids as a solvent to recover bitumen from a tar sand. An improvement to the original process, known as the Beaver-Herter process, utilizes short-chain alcohols as a cosolvent to enhance the phase separation steps and to improve the saponification and desaponification reactions. The latest modification, known as the Wood-Beaver process, judiciously utilizes phase behavior to further improve the recovery of the fatty acids from the solvated mixture at greatly reduced chemical costs. This paper describes the latest modified process, discusses a conceptual design for a demonstration plant, and summarizes the equipment costs. 3 figures, 3 tables.

  20. Beaver dams and channel sediment dynamics on Odell Creek, Centennial Valley, Montana, USA

    NASA Astrophysics Data System (ADS)

    Levine, Rebekah; Meyer, Grant A.

    2014-01-01

    Beaver dams in streams are generally considered to increase bed elevation through in-channel sediment storage, thus, reintroductions of beaver are increasingly employed as a restoration tool to repair incised stream channels. Here we consider hydrologic and geomorphic characteristics of the study stream in relation to in-channel sediment storage promoted by beaver dams. We also document the persistence of sediment in the channel following breaching of dams. Nine reaches, containing 46 cross-sections, were investigated on Odell Creek at Red Rock Lakes National Wildlife Refuge, Centennial Valley, Montana. Odell Creek has a snowmelt-dominated hydrograph and peak flows between 2 and 10 m3 s- 1. Odell Creek flows down a fluvial fan with a decreasing gradient (0.018-0.004), but is confined between terraces along most of its length, and displays a mostly single-thread, variably sinuous channel. The study reaches represent the overall downstream decrease in gradient and sediment size, and include three stages of beaver damming: (1) active; (2) built and breached in the last decade; and (3) undammed. In-channel sediment characteristics and storage were investigated using pebble counts, fine-sediment depth measurements, sediment mapping and surveys of dam breaches. Upstream of dams, deposition of fine (≤ 2 mm) sediment is promoted by reduced water surface slope, shear stress and velocity, with volumes ranging from 48 to 182 m3. High flows, however, can readily transport suspended sediment over active dams. Variations in bed-sediment texture and channel morphology associated with active dams create substantial discontinuities in downstream trends and add to overall channel heterogeneity. Observations of abandoned dam sites and dam breaches revealed that most sediment stored above beaver dams is quickly evacuated following a breach. Nonetheless, dam remnants trap some sediment, promote meandering and facilitate floodplain development. Persistence of beaver dam sediment

  1. Isolation and characterization of microsatellite loci in the beaver (Castor canadensis).

    PubMed

    Crawford, J; Liu, Z; Nelson, T; Nielsen, C; Bloomquist, C

    2008-05-01

    We have isolated and characterized 10 microsatellite loci in the beaver (Castor canadensis). Sixty individuals from southern and central Illinois were screened at each locus. All loci exhibited moderate levels of polymorphism, ranging from five to 13 alleles per locus with average heterozygosity ranging from 0.317 to 0.867. Locus Cca5 deviated significantly from HWE (P < 0.001). The locus pair Cca4/Cca5 was shown to be in linkage disequilibrium in southern Illinois, but not in the central Illinois population. The remaining eight loci will be useful in investigations of mating and kinship patterns in beaver populations in Illinois. © 2007 Eastern Illinois University.

  2. Systemic toxoplasmosis in a five-month-old beaver, (Castor canadensis).

    PubMed

    Forzán, María J; Frasca, Salvatore

    2004-03-01

    A 5-mo-old orphan beaver, Castor canadensis, died of severe systemic toxoplasmosis during rehabilitation. Histologic lesions included lymphohistiocytic encephalitis, myocarditis, and interstitial pneumonia with multinucleated cells. Intracytoplasmic cysts containing tachyzoites and bradyzoites identified as Toxoplasma gondii by immunohisto-chemistry were present in macrophages, type-II pneumocytes, and endothelial cells. Immunohistochemistry using a polyclonal morbillivirus antibody and transmission electron microscopy of lung revealed no evidence of concurrent paramyxoviral infection, as commonly found in carnivores with toxoplasmosis. Toxoplasmosis may affect young beavers in rehabilitation and zoological settings.

  3. BOREAS TGB-5 Dissolved Organic Carbon Data from NSA Beaver Ponds

    NASA Technical Reports Server (NTRS)

    Bourbonniere, Rick; Hall, Forrest G. (Editor); Conrad, Sara K. (Editor)

    2000-01-01

    The BOReal Ecosystem-Atmosphere Study Trace Gas Biogeochemistry (BOREAS TGB-5) team collected several data sets related to carbon and trace gas fluxes and concentrations in the Northern Study Area (NSA). This data set contains concentrations of dissolved organic and inorganic carbon species from water samples collected at various NSA sites. In particular, this set covers the NSA Tower Beaver Pond Site and the NSA Gillam Road Beaver Pond Site, including data from all visits to open water sampling locations during the BOREAS field campaigns from April to September 1994. The data are provided in tabular ASCII files.

  4. Seasonal variation in diel carbon dynamics, Beaver Creek, Alaska

    NASA Astrophysics Data System (ADS)

    Dornblaser, M.; Striegl, R. G.

    2013-12-01

    Aquatic carbon (C) dynamics are relatively well studied for boreal river systems at basin and catchment scales, but are less well know for intermediate tributaries as they transform, transport, and degas C. Lack of easy access to remote northern rivers and streams hinders the collection of high frequency data that can shed light on short time scale C dynamics. However, recent advances in sensor technology have improved our ability to gather such information. We present sensor data for Beaver Creek, Alaska, an intermediate-sized tributary to the Yukon River, focusing on diel time scale patterns that would be unattainable through discrete sampling alone. Dissolved carbon dioxide partial pressure (pCO2) exhibited a diel pattern throughout the open water season, with the greatest amplitude in mid-summer. In early summer, pCO2 peaked in early evening, possibly due to a concentration effect. Coincidentally, this early season was the only period when discharge (Q) exhibited a diel pattern, with flow maxima in early morning and minima in early evening. This suggests an evapotranspiration (ET) signal during this period. In mid and late-summer, pCO2 peaked near 6:00 am, fitting with expected photosynthesis/respiration (P/R) effects. However, while oxygen also exhibited a diel pattern consistent with P/R, the daily amplitude was small, and stream metabolism rates were low, suggesting that pCO2 was largely driven by physical factors. Fluorescent dissolved organic matter (FDOM) also exhibited diel patterns throughout the open water season, with greatest amplitude occurring in early summer. For much of the season, FDOM exhibited minima in early evening, suggesting photo degradation. In addition to the diel pattern, FDOM exhibited a response to changing Q, with lag times ranging from about 6 hours (early season) to 24 hours (late season).

  5. Retinal emboli and cardiovascular disease: the Beaver Dam Eye Study.

    PubMed Central

    Klein, Ronald; Klein, Barbara E K; Moss, Scot E; Meuer, Stacy M

    2003-01-01

    PURPOSE: To describe the 10-year incidence of retinal emboli, the associated risk factors, and the relationship of retinal emboli to stroke and ischemic heart disease mortality. METHODS: The Beaver Dam Eye Study (n = 4,926) is a population-based study of persons 43 to 86 years of age. Retinal emboli were detected at baseline (1988-1990) and at a 5-year (1993-1995) and a 10-year (1998-2000) follow-up by grading of stereoscopic 30 degrees color fundus photographs using standardized protocols. Cause-specific mortality was determined from death certificates. RESULTS: The 10-year cumulative incidence of retinal emboli was 1.5%. While adjusting for age and sex, the incidence of retinal emboli was associated with increased pulse pressure (odds ratio [OR] 4th versus 1st quartile range, 2.42; 95% confidence interval (CI), 0.98-5.97; P test of trend = .03), higher serum total cholesterol (OR, 2.77; 95% CI, 1.06-7.23; P = .03), higher leukocyte count (OR, 2.28; 95% CI, 1.04-4.96; P = .05), smoking status (OR current versus never smoker, 4.60: 95% CI, 2.08-10.16; P < .001), and a history of coronary artery bypass surgery (OR, 7.17; 95% CI, 3.18-16.18; P < .001) at baseline. While controlling for age, sex, and systemic factors, a significantly higher hazard of dying with a mention of stroke on the death certificate was found in people with retinal emboli (hazard ratio, 2.40; 95% CI, 1.16-4.99) compared with those without. CONCLUSIONS: The data show an association of smoking and cardiovascular disease with the incidence of retinal emboli. Also, persons with retinal emboli are at increased risk of stroke-related death. PMID:14971575

  6. Beaver dams, sediment dynamics and morphological change, Odell Creek, southwest Montana

    NASA Astrophysics Data System (ADS)

    Levine, R.; Meyer, G. A.

    2012-12-01

    Beaver (Castor canadensis) were historically part of riverine systems across North America, and enhancement of beaver populations is increasingly considered an important remedy for stream degradation problems such as incised channels. However, how beaver affect fluvial processes and resulting morphology in different fluvial environments and on various channel types requires further attention. We examine the effects of beaver damming on Odell Creek, a relatively high-energy piedmont stream in the upper Missouri River basin of southwest Montana, where air photo and real-time observations indicate that main-channel dams typically persist for only a few years. Odell Creek has a basin area of 46 km2, a snowmelt-dominated hydrograph, and peak flows of 2-10 m3s-1. Odell Creek is broadly incised along most of its length within a late Pleistocene fluvial fan surface, with mean floodplain width between confining terraces of 240 m. Channel gradient declines downstream from 0.018 - 0.004, and mean channel width for 46 cross-sections is 8.1 m. We examined the geomorphic effects of active beaver dams and the persistence of dam-induced changes in nine study reaches representing downstream channel variability and variations in dam history. In-channel sediment characteristics and storage were investigated using pebble counts, fine sediment surveys and bed sediment mapping. Discharges exceeding bankfull during 2011 spring runoff breached three active dams within reaches surveyed in 2009 and 2010, allowing for repeat channel cross-section and sediment surveys. Channel geometry and sediment analyses were also conducted at several other active and breached dam sites. Volumes of fine (≤ 2 mm) sediment stored upstream of active beaver dams ranged from 40 - 135 m3. Observations and surveys of abandoned dam sites and dam breaches revealed that the majority of sediment stored upstream of beaver dams is quickly evacuated following a breach. However, while general aggradation from damming

  7. Surface water of Beaver Creek Basin, in South-Central Oklahoma

    USGS Publications Warehouse

    Laine, L.L.; Murphy, J.J.

    1962-01-01

    Annual discharge from Beaver Creek basin is estimated to have averaged 217,000 acre-feet during a 19-year base period, water years 1938-56, equivalent to an average annual runoff depth of 4.7 inches over the 857 square-mile drainage area. About 55,000 acre-feet per year comes from Little Beaver Creek basin, a tributary drainage of 195 square miles. Yearly streamflow is highly variable. The discharge of Little Beaver Creek near Duncan during 13-year period of record (water years 1949-61) has ranged from 86,530 acre-feet in calendar year 1957 to 4,880 acre-feet in 1956, a ratio of almost 18 to 1. Highest runoff within a year tends to occur in the spring months of May and June, a 2-month period that, on the average, accounts for more than half of the annual discharge of Little Beaver Creek near Duncan. The average monthly runoff during record was lowest in January. Variation in daily streamflow is such that while the average discharge for the 13-year period of record was 50.1 cfs (cubic feet per second), the daily discharge was more than 6 cfs only about half of the time. There was no flow at the site 19 percent of the time during the period. Some base runoff usually exists in the headwaters of Beaver and Little Beaver Creeks, and in the lower reaches of Beaver Creek. Low flow in Cow Creek tends to be sustained by waste water from Duncan, where water use in 1961 averaged 4 million gallons per day. In the remainder of the basin, periods of no flow occur in most years. The surface water of Beaver Creek basin is very hard but in general is usable for municipal, agricultural and industrial purposes. The chemical character of the water is predominantly a calcium, magnesium bicarbonate type of water in the lower three quarters of the basin, except in Cow Creek where oil-field brines induce a distinct sodium, calcium chloride characteristic at low and medium flows. A calcium sulfate type of water occurs in most of the northern part of the basin except in headwater areas

  8. First year results from an experimental study of the ecohydrologic benefits of beaver and beaver dam analogue restoration techniques in Childs Meadow, CA

    NASA Astrophysics Data System (ADS)

    Yarnell, S. M.; Pope, K.; Podolak, K.; Wolf, E.; Burnett, R.

    2016-12-01

    Due to extensive livestock grazing and widespread removal of beaver and willows, headwater meadows have transformed from multi-thread channels with seasonally active floodplains into single thread, incised channels that store less carbon, retain less water, and are lower in habitat quality for a diverse suite of meadow-dependent wildlife. Meadow restoration techniques often include willow planting and cattle exclosures; however, few studies have rigorously tested the long-term efficacy of these methods or evaluated alternative restoration techniques such as reintroduction of beaver or installation of beaver dam analogues (BDAs). This project seeks to evaluate the installation of BDAs as a restoration technique in Childs Meadow, a heavily grazed meadow in the Cascade Range representative of low-gradient meadows across northern California. Using a before-after-control-impact study design, the study tests the impacts of two restoration techniques (willow planting with cattle exclusion and willow planting with cattle exclusion and BDAs) on hydrology, carbon sequestration, and sensitive species. Results will be compared with measurements in an unrestored section of the meadow that currently supports an active beaver population and two imperiled species (Cascades Frog and Willow Flycatcher). One specific project objective is to measure the response of hydrogeomorphic conditions (e.g. groundwater, surface water, temperature, habitat) and Cascades Frog and Willow Flycatcher to restorative actions. Pre-treatment data was collected in summer 2015, a cattle exclosure was established and willows were planted in fall 2015, and installation of the BDAs is planned for fall 2016. Three years of post-implementation monitoring will be completed to assess impacts of the treatments. Here, we will present our sampling design and first year results following initiation of the treatments.

  9. Seasonal foraging responses of beavers to sodium-enhanced foods: An experimental assessment with field feeding trials

    USGS Publications Warehouse

    Strules, Jennifer; Destefano, Stephen

    2015-01-01

    Salt drive is a seasonal phenomenon common to several classes of wild herbivores. Coincident with shifts of nutrient quality when plants resume growth in the spring, sodium is secondarily lost as surplus potassium is excreted. The beaver (Castor canadensis) is an herbivore whose dietary niche closely follows that of other herbivores that are subject to salt drive, but no published studies to date have assessed the likelihood of its occurrence. To quantify if beavers experience seasonal salt drive, we designed a field experiment to measure the foraging responses of beavers to sodium-enhanced foods. We used sodium-treated (salted) and control (no salt) food items (aspen [Populus tremuloides] and pine [Pinus spp.] sticks) during monthly feeding trials at beaver-occupied wetlands. If conventional ontogeny of salt drive was operant, we expected to observe greater utility of sodium-treated food items by beavers in May and June. Further, if water lilies (Nymphaea spp. and Nuphar spp.) supply beavers with sodium to meet dietary requirements as is widely speculated, we expected foraging responses to sodium-treated food items at wetlands where water lilies were absent to be greater than at wetlands where water lily was present. Aspen was selected by beavers in significantly greater amounts than pine. There was no difference between the mean percent consumed of salted and control aspen sticks by beavers at lily and non-lily wetlands, and no differences in temporal consumption associated with salted or control pine sticks at either wetland type. Salted pine was consumed in greater amounts than unsalted pine. We propose that the gastrointestinal or renal physiology of beavers may preclude solute loss, thereby preventing salt drive.

  10. A global review on the influence of beavers (Castor fiber, Castor canadensis) on river and floodplain dynamics

    NASA Astrophysics Data System (ADS)

    Larsen, Annegret; Lane, Stuart; Larsen, Joshua

    2017-04-01

    Beavers (Castor fiber, Castor canadensis) have the ability to actively engineer their habitat, which they can do most effectively in lower order streams and their floodplains. Hence, this engineering has the potential to alter the hydrology, geomorphology, biogeochemistry, and ecology of river systems and the feedbacks between them. Thus, the beaver is often referred to as an 'ecosystem engineer' and is reflected in their recognition as a key species when restoring ecosystems. This capacity to engineer low order streams also shapes a range of positive and negative perceptions on their influence. On the one hand they may be perceived as capable of undermining existing river engineering schemes and the land use of associated floodplains, and on the other hand beavers may provide an alternative to traditional 'hard' engineering, potentially improving river restoration success. The aim of this review is to summarize research to date on the impacts of beavers on stream and floodplain hydrology, geomorphology, water-quality and ecology, and the feedbacks between them. Our review shows that: (1) research has been focused heavily on North American streams, with far less research outside this North American context; (2) there is a tendency to investigate beaver impacts from the perspective of individual disciplines, to the detriment of considering broader process feedbacks, notably at the interface of hydro-geomorphology and riparian ecology; (3) it remains unclear to which extent beavers genuinely engineered streams prior to human impact, pointing to the need for longer term (millennium scale) studies on how beavers have changed river-floodplain systems. Crucially, we conclude that the investigation of the effects of beavers on streams and floodplains, especially in a longer-term, and their use for river restoration can only be understood through the thorough investigation of antecedent hydro-geomorphic conditions which takes account of the ways in which beavers and humans

  11. Estimating abundance and survival in the endangered Point Arena Mountain beaver using noninvasive genetic methods

    Treesearch

    William J. Zielinski; Fredrick V. Schlexer; T. Luke George; Kristine L. Pilgrim; Michael K. Schwartz

    2013-01-01

    The Point Arena mountain beaver (Aplodontia rufa nigra) is federally listed as an endangered subspecies that is restricted to a small geographic range in coastal Mendocino County, California. Management of this imperiled taxon requires accurate information on its demography and vital rates. We developed noninvasive survey methods, using hair snares to sample DNA and to...

  12. Multiple resource evaluations on the Beaver Creek watershed: An Annotated Bibliography (1956-1996)

    Treesearch

    M. B. Baker; P. F. Ffolliott

    1998-01-01

    The Beaver Creek experimental watershed, located in north-central Arizona, was established in 1956 in response to public concerns that the flow of streams and the amount of livestock forage on watersheds in the Salt-Verde River Basins were being reduced by increasing densities of ponderosa pine saplings and pinyon-juniper trees. Natural resource responses to the...

  13. Recycling at Penn State's Beaver Stadium. "Recycle on the Go" Success Story

    ERIC Educational Resources Information Center

    US Environmental Protection Agency, 2009

    2009-01-01

    With a 13-year-old recycling program, The Pennsylvania State University's (Penn State) Beaver Stadium in the past diverted nearly 30 tons of recyclables per year from local landfills. A new initiative to promote recycling in the stadium's tailgating area has helped Penn State more than triple its old recycling record, collecting 112 tons in 2008.…

  14. Some morphological, physiological and behavioral specializations in North American beavers (Castor canadensis).

    PubMed

    Carlson, M; Welker, W I

    1976-01-01

    In order to gain insight into the functional properties of the tail in North American beavers (Castor canadensis) we (1) examined morphological features of skeletal, muscular, vascular, cutaneous and neural structures; (2) determined the segmental organization of spinal roots and certain stimulus-response features of receptive fields of single dorsal root fibers; (3) mapped the main somatic sensory area (SI) of the cerebral neocortex, and (4) attempted to relate these findings to observations of tail behavior in living beavers. The behavioral observations revealed the beaver capable of forceful yet discrete movements of the tail in water. A morphological correlate of these motor skills was the distinct segmentally organized pattern of serial muscle tendon arrangements and spinal sensory and motor innervation. Neither the receptors innervating the scales or hairs of the tail, the stimulus-response properties of single dorsal root afferents, nor the representation of the tail in SI suggested unusual cutaneous sensory capabilities associated with the morphological and behavioral specializations exhibited by the beaver's tail.

  15. Anatomy of the heart in the North American beaver (Castor canadensis).

    PubMed

    Bisaillon, A

    1982-01-01

    The gross anatomy of the heart of the North American beaver (Castor canadensis) is described following the dissection of nine specimens of both sexes ranging in body weight from 10 to 26 kg. The general characteristics of the beaver heart are similar to those of other mammals. However, variations in details of anatomy exist, especially for the right atrium. The right auricle is divided into 2 appendages, one on each side of the ascending aorta. The orifices of the 3 venae cavae are guarded by a well developed valvular system. Other variations in relative size and shape exist and for these points the heart of the beaver is more closely related to that of aquatic than to that of terrestrial mammals. The heart has the form of a widened cone being transversely broad and flat from one surface to the other. The apex of the organ is formed by both ventricles except in 2 specimens in which only the left ventricle participates in its formation. The right ventricle in the beaver being relatively long and narrow, its general proportions approximate those found in the seals.

  16. Influence of flooding, freezing, and American beaver herbivory on survival of planted oak seedlings

    Treesearch

    Johnathan T. Reeves; Andrew W. Ezell; John D. Hodges; Emily B. Schultz; Andrew B. Self

    2016-01-01

    Good seedlings, proper planting, and competition control normally result in successful hardwood planting. However, other factors can have serious impact on planting success, such as the impact of flooding, freezing, and the American beaver (Castor canadensis). In 2014, three planting stocks of Nuttall oak (Quercus nuttallii) and Shumard oak (

  17. Reproductive characteristics of the Point Arena mountain beaver (Aplodontia rufa nigra)

    Treesearch

    William Zielinski; M. J. Mazurek

    2016-01-01

    Little is known about the ecology and life history of the federally endangered Point Arena mountain beaver (Aplodontia rufa nigra). The distribution of this primitive burrowing rodent is disjunct from the balance of the species’ range and occurs in a unique maritime environment of coastal grasslands and forests. Fundamental to protecting this taxon...

  18. A Feasibility Study for Consolidating and/or Coordinating Technical Procedures in Beaver County Pennsylvania Libraries.

    ERIC Educational Resources Information Center

    Fry, James W.

    In 1977 the Public Library Commission, in conjunction with the State Library of Pennsylvania, received a Library Services and Construction Act, Title III Grant to conduct a feasibility study of technical service operations in various types of libraries within Beaver County. Its objectives were to: (1) analyze existing library materials purchasing…

  19. From Impasse to "Lockout": Community College of Beaver County, September 1976. Special Report #30.

    ERIC Educational Resources Information Center

    Bacon, Janet Novotny

    This document analyzes the events and circumstances surrounding the collective negotiations between faculty and administration at the Community College of Beaver County (Pennsylvania) during the summer of 1976; the impasse that resulted concerning the issue of retrenchment; the Board's refusal to accept a faculty offer to continue negotiations…

  20. Beaver dams maintain fish biodiversity by increasing habitat heterogeneity throughout a low-gradient stream network

    USGS Publications Warehouse

    Smith, Joseph M.; Mather, Martha E.

    2013-01-01

    In summary, within a stream network, beaver dams maintained fish biodiversity by altering in-stream habitat and increasing habitat heterogeneity. Understanding the relationship between habitat heterogeneity and biodiversity can advance basic freshwater ecology and provide science-based support for applied aquatic conservation

  1. Tom Beaver, Creek Television Reporter. With Teacher's Guide. Native Americans of the Twentieth Century.

    ERIC Educational Resources Information Center

    Minneapolis Public Schools, MN.

    A biography for elementary school students presents an account of an American Indian television reporter, Tom Beaver (Creek), and includes a map of Oklahoma showing the location of Indian tribes. A teacher's guide following the biography contains information about the Creek tribe and the history of television, learning objectives and directions…

  2. Development and characterization of microsatellite markers in the Point Arena mountain beaver Aplodontia rufa nigra

    Treesearch

    Kristine L. Pilgrim; William J. Zielinski; Mary J. Mazurek; Frederick V. Schlexer; Michael K. Schwartz

    2006-01-01

    The Point Arena mountain beaver (Aplodontia rufa nigra) is an endangered subspecies. Efforts to recover this sub-species will be aided by advances in molecular genetics, specifically the ability to estimate population size using noninvasive genetic sampling. Here we report on the development of nine polymorphic loci for the Point Arena mountain...

  3. Establishment of a health surveillance program for reintroduction of the Eurasian beaver (Castor fiber) into Scotland.

    PubMed

    Goodman, Gidona; Girling, Simon; Pizzi, Romain; Meredith, Anna; Rosell, Frank; Campbell-Palmer, Roisin

    2012-10-01

    In 2009 and 2010 16 Norwegian Eurasian beavers (Castor fiber) were reintroduced to Knapdale, Scotland as part of a 5-yr reintroduction trial (Scottish Beaver Trial). Despite numerous reintroduction programs throughout Europe there is no published information concerning recommended health surveillance during beaver reintroduction and only one publication describing causes of mortality. We describe the establishment of a health surveillance program based on International Union of Conservation of Nature (IUCN) and governmental guidelines, and report preliminary results based on the fecal and blood samples following the completion of the first stage of reintroduction. Animals underwent at least one general anesthetic to allow collection of fecal and blood samples and a thorough clinical examination. No bacterial enteric pathogens such as Salmonella spp., Campylobacter spp., or Yersinia pseudotuberculosis were isolated, nor were Giardia spp. or Cryptosporidium spp. However, numerous helminths including Travassosius rufus and Stichorchis subtriquetrus were detected. Five animals were positive for Leptospira antibodies. This included Leptospira saxkoebing, Leptospira canicola, Leptospira copenhageni, Leptospira icterohaemorrhagiae, Leptospira autumnalis, and Leptospira javanica. The highest loss of animals (20%) was during the statutory 6-mo rabies quarantine period. No common cause of death was determined. The rabies quarantine conditions were waived for four remaining animals, three of which were introduced to the wild successfully. The authors recommend the shortest possible quarantine period when introducing beavers, but allowing for the minimum recommended IUCN 35 days to allow for implementation of the initial stage of the health surveillance program, examination of animals, sample collection, and processing.

  4. Long-Term Hydrological Reconstruction From a Beaver Meadow Using Testate Amoebae

    NASA Astrophysics Data System (ADS)

    Von Ness, K.; Loisel, J.; Karran, D. J.; Westbrook, C.; Kohlmeyer, C.

    2016-12-01

    Beaver ponds contribute up to 0.8 Tg/yr of atmospheric methane (CH4) globally (Whitfield et al., 2014) and were found to be the largest CH4 emitters among all the wetland types in boreal environments (Roulet et al., 1992). However, the sources and underlying mechanisms of carbon emission and sequestration in beaver ponds requires further elucidation. Here we present the historical development of a beaver meadow located in the Sibbald Research Wetland in the Rocky Mountains of Kananaskis Provincial Park, Alberta, Canada. We use a combination of testate amoebae, plant macrofossils, and other geochemical proxies to provide high-resolution reconstructions along three peat cores extracted in hydrologically distinct portions of the meadow. To our knowledge, this is the first attempt at reconstructing long-term hydrological conditions in these systems. Testate amoebae (Protozoa: Rhizopoda) are single-celled organisms that inhabit moist substrates and produce a decay-resistant test. As each taxon generally occupies a discrete ecological niche related to soil moisture and pH, testate amoebae are good indicators of past and ongoing hydrological change. Preliminary analysis of testate amoebae assemblages downcore suggests that this proxy is suitable to reconstruct hydrological changes in meadows, with wetter and drier communities being in good agreement with wetter and drier plant macrofossil assemblages. The nitrogen isotopic signature of peat samples (ongoing) will be used as a proxy for changes in nutrient input; it could become a proxy for past beaver activity.

  5. Determinants of Retinal Venular Diameter: the Beaver Dam Eye Study

    PubMed Central

    Myers, Chelsea E.; Klein, Ronald; Knudtson, Michael D.; Lee, Kristine E.; Gangnon, Ronald; Wong, Tien Y.; Klein, Barbara E. K.

    2012-01-01

    Objective To describe how retinal venular diameter changes over time for an individual and to examine differences in these changes among people with different risk profiles. Design Population-based cohort study. Participants 4600 persons aged 43–86 years from the Beaver Dam Eye Study who participated in at least 1 examination and had venular diameter measured in the right eye. Methods Data from 4 examinations over 15 years were analyzed. Retinal venular diameter was measured from photographs at each examination by computer-assisted methods and summarized as the central retinal venular equivalent (CRVE). Associations of risk factors to concurrent CRVE measurements and changes in CRVE over time were determined using multivariate analyses. Main Outcome Measure CRVE. Results CRVE tended to narrow with age. Mean CRVE was about 5 µm smaller (225 vs. 230 µm) for the average 70-year-old compared to the average 50-year-old, and was about 13 µm smaller (217 vs. 230 µm) for the average 85-year-old compared to the average 50-year-old. Male sex (beta estimate [β]=5.34; 95% confidence interval [CI] 3.58, 6.90), current smoking (β=9.38; 95% CI 8.26, 10.49), and higher white blood cell count (per 1000/µL: β=0.95; 95% CI 0.74, 1.16) were independently associated with larger concurrent CRVE while higher mean arterial blood pressure (per 5 mmHg: β=−0.36; 95% CI −0.50, −0.23) and higher high-density lipoprotein cholesterol (per 10 mg/dL: β=−0.89; 95% CI −1.15, −0.63) were independently associated with smaller concurrent CRVE. History of cardiovascular disease (β=−0.16; 95% CI −0.26, −0.06) and presence of chronic kidney disease (β=−0.20; 95% CI −0.34, −0.05) were associated with a greater decrease in CRVE over time. Conclusions These data show that retinal venular diameter tended to narrow with age, and that concurrent venular diameter is independently associated with sex, blood pressure, high-density lipoprotein cholesterol, white blood cell

  6. De Novo Genome and Transcriptome Assembly of the Canadian Beaver (Castor canadensis).

    PubMed

    Lok, Si; Paton, Tara A; Wang, Zhuozhi; Kaur, Gaganjot; Walker, Susan; Yuen, Ryan K C; Sung, Wilson W L; Whitney, Joseph; Buchanan, Janet A; Trost, Brett; Singh, Naina; Apresto, Beverly; Chen, Nan; Coole, Matthew; Dawson, Travis J; Ho, Karen; Hu, Zhizhou; Pullenayegum, Sanjeev; Samler, Kozue; Shipstone, Arun; Tsoi, Fiona; Wang, Ting; Pereira, Sergio L; Rostami, Pirooz; Ryan, Carol Ann; Tong, Amy Hin Yan; Ng, Karen; Sundaravadanam, Yogi; Simpson, Jared T; Lim, Burton K; Engstrom, Mark D; Dutton, Christopher J; Kerr, Kevin C R; Franke, Maria; Rapley, William; Wintle, Richard F; Scherer, Stephen W

    2017-02-09

    The Canadian beaver (Castor canadensis) is the largest indigenous rodent in North America. We report a draft annotated assembly of the beaver genome, the first for a large rodent and the first mammalian genome assembled directly from uncorrected and moderate coverage (< 30 ×) long reads generated by single-molecule sequencing. The genome size is 2.7 Gb estimated by k-mer analysis. We assembled the beaver genome using the new Canu assembler optimized for noisy reads. The resulting assembly was refined using Pilon supported by short reads (80 ×) and checked for accuracy by congruency against an independent short read assembly. We scaffolded the assembly using the exon-gene models derived from 9805 full-length open reading frames (FL-ORFs) constructed from the beaver leukocyte and muscle transcriptomes. The final assembly comprised 22,515 contigs with an N50 of 278,680 bp and an N50-scaffold of 317,558 bp. Maximum contig and scaffold lengths were 3.3 and 4.2 Mb, respectively, with a combined scaffold length representing 92% of the estimated genome size. The completeness and accuracy of the scaffold assembly was demonstrated by the precise exon placement for 91.1% of the 9805 assembled FL-ORFs and 83.1% of the BUSCO (Benchmarking Universal Single-Copy Orthologs) gene set used to assess the quality of genome assemblies. Well-represented were genes involved in dentition and enamel deposition, defining characteristics of rodents with which the beaver is well-endowed. The study provides insights for genome assembly and an important genomics resource for Castoridae and rodent evolutionary biology. Copyright © 2017 Lok et al.

  7. Stichorchis subtriquetrus (Digenea: Paramphistomatidae) from Eurasian beaver (Castor fiber) in the Czech Republic.

    PubMed

    Máca, Ondřej; Pavlásek, Ivan; Vorel, Aleš

    2015-08-01

    Between March 2012 and April 2014, we performed post-mortem parasitological examinations of 11 Eurasian beavers (Castor fiber Linnaeus, 1758) from the basins of four main rivers (Dyje, Labe, Morava, Vltava) in the Czech Republic. The cause of death of five adult animals was unknown, three adult animals died after being hit by cars, while one young and one adult as a result of serious injuries and one juvenile male drowned. The trematode Stichorchis subtriquetrus (Rudolphi, 1814) Lühe, 1909 was only found in the caecum body and caecum apex of nine beavers (82%), with no significant differences in parasite intensity among beavers. The highest number of trematodes (271) occurred in an adult female in July 2013; while a range of 1-57 individuals were found in other positive beavers. S. subtriquetrus size in both parts of the caecum was 11.0-17.0 × 5.5-8.0 mm (mean 14.3 × 6.9 mm). Results demonstrated that for the optimal detection of eggs, it was necessary to examine at least 10 g of faeces with a new modified method of sedimentation. The size range of 30 eggs was 157.1-182.5 × 99.3-109.8 μm (mean 168.0 × 104.4 μm). There were no differences in prevalence and seasonal occurrence of S. subtriquetrus between male and female beavers. We did not find any other intestinal endoparasites or tissue parasites (Sarcocystis spp., Trichinella spp.).

  8. De Novo Genome and Transcriptome Assembly of the Canadian Beaver (Castor canadensis)

    PubMed Central

    Lok, Si; Paton, Tara A.; Wang, Zhuozhi; Kaur, Gaganjot; Walker, Susan; Yuen, Ryan K. C.; Sung, Wilson W. L.; Whitney, Joseph; Buchanan, Janet A.; Trost, Brett; Singh, Naina; Apresto, Beverly; Chen, Nan; Coole, Matthew; Dawson, Travis J.; Ho, Karen; Hu, Zhizhou; Pullenayegum, Sanjeev; Samler, Kozue; Shipstone, Arun; Tsoi, Fiona; Wang, Ting; Pereira, Sergio L.; Rostami, Pirooz; Ryan, Carol Ann; Tong, Amy Hin Yan; Ng, Karen; Sundaravadanam, Yogi; Simpson, Jared T.; Lim, Burton K.; Engstrom, Mark D.; Dutton, Christopher J.; Kerr, Kevin C. R.; Franke, Maria; Rapley, William; Wintle, Richard F.; Scherer, Stephen W.

    2017-01-01

    The Canadian beaver (Castor canadensis) is the largest indigenous rodent in North America. We report a draft annotated assembly of the beaver genome, the first for a large rodent and the first mammalian genome assembled directly from uncorrected and moderate coverage (< 30 ×) long reads generated by single-molecule sequencing. The genome size is 2.7 Gb estimated by k-mer analysis. We assembled the beaver genome using the new Canu assembler optimized for noisy reads. The resulting assembly was refined using Pilon supported by short reads (80 ×) and checked for accuracy by congruency against an independent short read assembly. We scaffolded the assembly using the exon–gene models derived from 9805 full-length open reading frames (FL-ORFs) constructed from the beaver leukocyte and muscle transcriptomes. The final assembly comprised 22,515 contigs with an N50 of 278,680 bp and an N50-scaffold of 317,558 bp. Maximum contig and scaffold lengths were 3.3 and 4.2 Mb, respectively, with a combined scaffold length representing 92% of the estimated genome size. The completeness and accuracy of the scaffold assembly was demonstrated by the precise exon placement for 91.1% of the 9805 assembled FL-ORFs and 83.1% of the BUSCO (Benchmarking Universal Single-Copy Orthologs) gene set used to assess the quality of genome assemblies. Well-represented were genes involved in dentition and enamel deposition, defining characteristics of rodents with which the beaver is well-endowed. The study provides insights for genome assembly and an important genomics resource for Castoridae and rodent evolutionary biology. PMID:28087693

  9. National Dam Inspection Program, Big Beaver Dam (Pa No Name Number 14, NDI Number PA 00258, PennDER Number 4-11), Ohio River Basin, Tributary of Clark’s Run, Beaver County, Pennsylvania. Phase I Inspection Report,

    DTIC Science & Technology

    1980-02-01

    the Allegheny Group , Pennsylvanian System. These members consist of cyclic sequences of shale, sandstone, limestone, and coal. It is estimated that the...4, GEOLOGIC MAP Blg Beaver Dom NDI No. PA 00258 Beaver County c Reproduced from Greater Pittsburgh Region Geologic Map. -A% 0 4 Compiled by W. R...Wagner and others, 1975 N Scale: One Inch Equals Approximately Two Miles See Legend, Next Page GEOLOGY MAP LEGEND GROUP FORMATION DESCRIPTION Alluvium

  10. Analysis of ambient conditions and simulation of hydrodynamics and water-quality characteristics in Beaver Lake, Arkansas, 2001 through 2003

    USGS Publications Warehouse

    Galloway, Joel M.; Green, W. Reed

    2006-01-01

    Beaver Lake is a large, deep-storage reservoir located in the upper White River Basin in northwestern Arkansas. The purpose of this report is to describe the ambient hydrologic and water-quality conditions in Beaver Lake and its inflows and describe a two-dimensional model developed to simulate the hydrodynamics and water quality of Beaver Lake from 2001 through 2003. Water-quality samples were collected at the three main inflows to Beaver Lake; the White River near Fayetteville, Richland Creek at Goshen, and War Eagle Creek near Hindsville. Nutrient concentrations varied among the tributaries because of land use and contributions of nutrients from point sources. The median concentrations of total ammonia plus organic nitrogen were greater for the White River than Richland and War Eagle Creeks. The greatest concentrations of nitrite plus nitrate and total nitrogen, however, were observed at War Eagle Creek. Phosphorus concentrations were relatively low, with orthophosphorus and dissolved phosphorus concentrations mostly below the laboratory reporting limit at the three sites. War Eagle Creek had significantly greater median orthophosphorus and total phosphorus concentrations than the White River and Richland Creek. Dissolved organic-carbon concentrations were significantly greater at the White River than at War Eagle and Richland Creeks. The White River also had significantly greater turbidity than War Eagle Creek and Richland Creek. The temperature distribution in Beaver Lake exhibits the typical seasonal cycle of lakes and reservoirs located within similar latitudes. Beaver Lake is a monomictic system, in which thermal stratification occurs annually during the summer and fall and complete mixing occurs in the winter. Isothermal conditions exist throughout the winter and early spring. Nitrogen concentrations varied temporally, longitudinally, and vertically in Beaver Lake for 2001 through 2003. Nitrite plus nitrate concentrations generally decreased from the

  11. Classification of the alterations of beaver dams to headwater streams in northeastern Connecticut, U.S.A.

    NASA Astrophysics Data System (ADS)

    Burchsted, Denise; Daniels, Melinda D.

    2014-01-01

    Of the many types of barriers to water flow, beaver dams are among the smallest, typically lasting less than a decade and rarely exceeding 1.5 m in height. They are also among the most frequent and common obstructions in rivers, with a density often exceeding ten dams per km, a frequency of construction within a given network on a time scale of years, and a historic extent covering most of North America. Past quantification of the geomorphologic impact of beaver dams has primarily been limited to local impacts within individual impoundments and is of limited geographic scope. To assess the impact of beaver dams at larger scales, this study examines channel shape and sediment distribution in thirty river reaches in northeastern Connecticut, U.S.A. The study reaches fall within the broader categories of impounded and free-flowing segments, leaving a third segment class of beaver meadows requiring additional study. Each of the study reaches were classified at the reach scale as free-flowing, valley-wide beaver pond, in-channel beaver pond, and downstream of beaver dam. The bankfull channel width to depth ratios and channel widths normalized by watershed area vary significantly across the study reach classes. Additionally, reaches modified by beaver dams have finer sediment distributions. This paper provides the first quantitative geomorphic descriptions of the in-channel beaver pond and reaches downstream of beaver dams. Given the different channel shapes and sediment distributions, we infer that geomorphic processes are longitudinally decoupled by these frequent barriers that control local base level. These barriers generate heterogeneity within a river network by greatly increasing the range of channel morphology and by generating patches controlled by different processes. Therefore, in spite of the small size of individual beaver dams, the cumulative effect of multiple dams has the potential to modify processes at larger spatial scales. To improve assessment of the

  12. Eurasian beaver activity increases water storage, attenuates flow and mitigates diffuse pollution from intensively-managed grasslands.

    PubMed

    Puttock, Alan; Graham, Hugh A; Cunliffe, Andrew M; Elliott, Mark; Brazier, Richard E

    2017-01-15

    Beavers are the archetypal keystone species, which can profoundly alter ecosystem structure and function through their ecosystem engineering activity, most notably the building of dams. This can have a major impact upon water resource management, flow regimes and water quality. Previous research has predominantly focused on the activities of North American beaver (Castor canadensis) located in very different environments, to the intensive lowland agricultural landscapes of the United Kingdom and elsewhere in Europe. Two Eurasian beavers (Castor fiber) were introduced to a wooded site, situated on a first order tributary, draining from intensively managed grassland. The site was monitored to understand impacts upon water storage, flow regimes and water quality. Results indicated that beaver activity, primarily via the creation of 13 dams, has increased water storage within the site (holding ca. 1000m(3) in beaver ponds) and beavers were likely to have had a significant flow attenuation impact, as determined from peak discharges (mean 30±19% reduction), total discharges (mean 34±9% reduction) and peak rainfall to peak discharge lag times (mean 29±21% increase) during storm events. Event monitoring of water entering and leaving the site showed lower concentrations of suspended sediment, nitrogen and phosphate leaving the site (e.g. for suspended sediment; average entering site: 112±72mgl(-1), average leaving site: 39±37mgl(-1)). Combined with attenuated flows, this resulted in lower diffuse pollutant loads in water downstream. Conversely, dissolved organic carbon concentrations and loads downstream were higher. These observed changes are argued to be directly attributable to beaver activity at the site which has created a diverse wetland environment, reducing downstream hydrological connectivity. Results have important implications for beaver reintroduction programs which may provide nature based solutions to the catchment-scale water resource management issues

  13. Cardiovascular effects of halothane anesthesia after diazepam and ketamine administration in beavers (Castor canadensis) during spontaneous or controlled ventilation.

    PubMed

    Greene, S A; Keegan, R D; Gallagher, L V; Alexander, J E; Harari, J

    1991-05-01

    Fourteen adult beavers (Castor canadensis) weighing 16.5 +/- 4.14 kg (mean +/- SD) were anesthetized for surgical implantation of radio telemetry devices. Beavers were anesthetized with diazepam (0.1 mg/kg) and ketamine (25 mg/kg) administered IM, which provided smooth anesthetic induction and facilitated tracheal intubation. Anesthesia was maintained with halothane in oxygen via a semiclosed circle anesthetic circuit. Values for heart rate, respiratory rate, esophageal temperature, direct arterial blood pressure, end-tidal halothane concentration, and end-tidal CO2 tension were recorded every 15 minutes during the surgical procedure. Arterial blood samples were collected every 30 minutes to determine pH, PaO2, and PaCO2. Values for plasma bicarbonate, total CO2, and base excess were calculated. Ventilation was spontaneous in 7 beavers and controlled to maintain normocapnia (PaCO2 approx 40 mm of Hg) in 7 others. Vaporizer settings were adjusted to maintain a light surgical plane of anesthesia. Throughout the surgical procedure, all beavers had mean arterial pressure less than 60 mm of Hg and esophageal temperature less than 35 C. Mean values for arterial pH, end-tidal CO2, PaO2, and PaCO2 were significantly (P less than 0.05) different in spontaneously ventilating beavers, compared with those in which ventilation was controlled. Respiratory acidosis during halothane anesthesia was observed in spontaneously ventilating beavers, but not in beavers maintained with controlled ventilation. All beavers recovered unremarkably from anesthesia.

  14. Using occupancy models to accommodate uncertainty in the interpretation of aerial photograph data: status of beaver in Central Oregon, USA

    USGS Publications Warehouse

    Pearl, Christopher A.; Adams, Michael J.; Haggerty, Patricia K.; Urban, Leslie

    2015-01-01

    Beavers (Castor canadensis) influence habitat for many species and pose challenges in developed landscapes. They are increasingly viewed as a cost-efficient means of riparian habitat restoration and water storage. Still, information on their status is rare, particularly in western North America. We used aerial photography to evaluate changes in beaver occupancy between 1942–1968 and 2009 in upper portions of 2 large watersheds in Oregon, USA. We used multiple observers and occupancy modeling to account for bias related to photo quality, observers, and imperfect detection of beaver impoundments. Our analysis suggested a slightly higher rate of beaver occupancy in the upper Deschutes than the upper Klamath basin. We found weak evidence for beaver increases in the west and declines in eastern parts of the study area. Our study presents a method for dealing with observer variation in photo interpretation and provides the first assessment of the extent of beaver influence in 2 basins with major water-use challenges. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

  15. The role of beaver in shaping steelhead trout (Oncorhynchus mykiss) habitat complexity and thermal refugia in a central Oregon stream

    NASA Astrophysics Data System (ADS)

    Consolati, F.; Wheaton, J. M.; Neilson, B. T.; Bouwes, N.; Pollock, M. M.

    2012-12-01

    The incised and degraded habitat of Bridge Creek, tributary to the John Day River in central Oregon, is thought to be limiting the local population of ESA-listed steelhead trout (Oncorhynchus mykiss). Restoration efforts for this watershed are aimed to improve their habitat through reconnecting the channel with portions of its former floodplain (now terraces) to increase stream habitat complexity and the extent of riparian vegetation. This is being done via the installation of over a hundred beaver dam support (BDS) structures that are designed to either mimic beaver dams or support existing beaver dams. The overall objective of this study is to determine if the BDS structures have had an effect on stream channel habitat complexity and thermal refugia in selected sections of Bridge Creek. Analysis of stream temperature data in restoration treatment and control areas will show the effects of beaver dams on stream temperature. Analysis of aerial imagery and high resolution topographic data will exhibit how the number and types of geomorphic units have changed after the construction of beaver dams. Combined, the results of this research are aimed to increase our understanding of how beaver dams impact fish habitat and stream temperature.

  16. Effects of mountain beaver management and thinning on 15-year-old Douglas fir growth and survival.

    PubMed

    Campbell, Dan L; Engeman, Richard M; Farley, James P

    2015-07-01

    We examined 4-year growth of 15-year-old damaged and undamaged Douglas fir (Pseudotsuga menzesii) after integrating temporary population reductions of mountain beaver (Aplodontia rufa) with thinning in a pre-commercial hand-planted plantation in western Washington. Five treatment combinations were considered: (1) trapping mountain beavers in an unthinned area, (2) trapping before thinning to 65 trees/ha (160 trees/ac), (3) no trapping and thinning to 65 trees/ha, (4) no trapping and thinning to 146 trees/ha (360 trees/ac), and (5) no trapping and no thinning. Removal of ≥ 90 % of mountain beavers temporarily reduced mountain beaver activity whether the stand was unthinned or thinned. Diameter growth at breast height (dbh) was greater for undamaged trees than for damaged trees in thinned areas. Tree height growth was greatest in trapped areas whether thinned or not. No differences were detected in 4-year survival between trees damaged aboveground and those without aboveground damage, which may be related to undetected root damage to trees without aboveground damage. Basal diameter growth and dbh growth were greatest for areas thinned to 65 trees/ha. Seventy-eight percent of stomachs from mountain beaver trapped in winter contained Douglas fir root or stem materials. Overall, short-term removal of mountain beavers integrated with pre-commercial thinning promoted growth of crop trees.

  17. Managed flood effects on beaver pond habitat in a desert riverine ecosystem, bill williams river, Arizona USA

    USGS Publications Warehouse

    Andersen, D.C.; Shafroth, P.B.; Pritekel, C.M.; O'Neill, M. W.

    2011-01-01

    The ecological effects of beaver in warm-desert streams are poorly documented, but potentially significant. For example, stream water and sediment budgets may be affected by increased evaporative losses and sediment retention in beaver ponds. We measured physical attributes of beaver pond and adjacent lotic habitats on a regulated Sonoran Desert stream, the Bill Williams River, after ???11 flood-free months in Spring 2007 and Spring 2008. Neither a predicted warming of surface water as it passed through a pond nor a reduction in dissolved oxygen in ponds was consistently observed, but bed sediment sorted to finest in ponds as expected. We observed a river segment-scale downstream rise in daily minimum stream temperature that may have been influenced by the series of ??100 beaver ponds present. Channel cross-sections surveyed before and after an experimental flood (peak flow 65 m3/s) showed net aggradation on nine of 13 cross-sections through ponds and three of seven through lotic reaches. Our results indicate that beaver affect riverine processes in warm deserts much as they do in other biomes. However, effects may be magnified in deserts through the potential for beaver to alter the stream thermal regime and water budget. ?? Society of Wetland Scientists 2011.

  18. Spatial variation in fish assemblages across a beaver-influenced successional landscape

    USGS Publications Warehouse

    Schlosser, I.J.; Kallemeyn, L.W.

    2000-01-01

    Beavers are increasingly viewed as “ecological engineers,” having broad effects on physical, chemical, and biological attributes of north-temperate landscapes. We examine the influence of both local successional processes associated with beaver activity and regional geomorphic boundaries on spatial variation in fish assemblages along the Kabetogama Peninsula in Voyageurs National Park, northern Minnesota, USA. Fish abundance and species richness exhibited considerable variation among drainages along the peninsula. Geological barriers to fish dispersal at outlets of some drainages has reduced fish abundance and species richness. Fish abundance and species richness also varied within drainages among local environments associated with beaver pond succession. Fish abundance was higher in upland ponds than in lowland ponds, collapsed ponds, or streams, whereas species richness was highest in collapsed ponds and streams. Cluster analyses based on fish abundance at sites classified according to successional environment indicated that four species (northern redbelly dace, Phoxinus eos; brook stickleback, Culaea inconstans; finescale dace, P. neogaeus; and fathead minnow, Pimephales promelas), were predominant in all successional environments. Several less abundant species were added in collapsed ponds and streams, with smaller size classes of large lake species (e.g., black crappie, Pomoxis nigromaculatus; smallmouth bass, Micropertus dolomieui; yellow perch, Perca flavescens; and burbot, Lota lota) being a component of these less abundant species. The addition of smaller size classes of large lake species indicates that dispersal of early life-history stages from Kabetogama Lake played a role in determining the species richness and composition of less abundant species in successional environments on the peninsula. Furthermore, collapsed-pond and stream environments closer to Kabetogama Lake had higher species richness than similar successional sites located farther

  19. Beaver response to recurrent alien scents: scent fence or scent match?

    PubMed

    Sun; MÜller-schwarze

    1998-06-01

    By repeatedly presenting an alien scent to territory-owning beavers, Castor canadensis, we tested two competing hypotheses about the function of scent marking: scent fence and scent matching. The scent-fence hypothesis predicts that territory owners should respond increasingly strongly over time towards a recurrent alien scent because of the ineffectiveness of previous responses. The scent-matching hypothesis predicts that the intensity of response should be the same or decrease because, without the presence of the intruding signaller coupled with the chemical signal, the presence of the scent itself does not advertise the ownership of a territory. The response level of resident beaver families was stable to strangers' anal gland secretions (AGSs) and decreased to strangers' castoreum during a period of 6 days. These results support the scent-matching hypothesis but not the scent-fence hypothesis. Copyright 1998 The Association for the Study of Animal Behaviour. Copyright 1998 The Association for the Study of Animal Behaviour.

  20. Phenolic compounds from male castoreum of the North American beaver,Castor canadensis.

    PubMed

    Tang, R; Webster, F X; Müller-Schwarze, D

    1993-07-01

    North American beaver (Castor canadensis) mark their territories with castoreum, the contents of their castor sacs. In their territories, beaver respond with scent marking to experimental scent marks consisting of castoreum, or selected single components. In part, the unique odor of castoreum is due to large amounts of phenolic compounds. Purified phenolic components were analyzed by GC, GC-MS, and NMR; identifications were confirmed by comparing the spectra of synthetic phenols with those of the isolated phenols. Of the 15 phenols reported elsewhere, only five were confirmed in our analysis; the other 10 phenolic compounds are either absent or are not volatile enough to be detected by our methods. In addition, 10 phenolic compounds have been identified in this study that were not reported in the previous papers concerning the constitution of castoreum.

  1. Thyroid follicular carcinoma with pulmonary metastases in a beaver (Castor canadensis).

    PubMed

    Anderson, W I; Schlafer, D H; Vesely, K R

    1989-10-01

    An 11-yr-old female beaver (Castor canadensis) died after a 3 1/2 mo course of intermittent diarrhea, lethargy and anorexia. A postmortem examination revealed both a necrotizing ulcerative colitis and bilaterally enlarged thyroid glands. Histologically, the necrotizing colitis was similar to that caused by canine or feline parvovirus. Thyroid glands were multilobulated. Lobules were composed of irregularly arranged, variably sized follicles, some of which contained colloid. Follicles were lined by a pleomorphic population of tall cuboidal to columnar epithelial cells. Capsular invasion was present. Similar cells, forming follicles were present within the pulmonary parenchyma. This is the first documented case of a thyroid follicular carcinoma with pulmonary metastases in a beaver.

  2. Beavers indicate metal pollution away from industrial centers in northeastern Poland.

    PubMed

    Giżejewska, Aleksandra; Spodniewska, Anna; Barski, Dariusz; Fattebert, Julien

    2015-03-01

    Heavy metals are persistent environmental contaminants, and wild animals are increasingly exposed to the harmful effects of compounds of anthropogenic origin, even in areas distant from industrial centers. We used atomic absorption spectrometry to determine levels of cadmium (Cd), lead (Pb), copper (Cu), and zinc (Zn) in liver and kidney of wild Eurasian beavers (Castor fiber) in Poland. Cd concentrations in liver (0.21 ± 0.44 μg/g) and in kidney (2.81 ± 4.52 μg/g) were lower in juvenile than in adult beavers. Pb concentrations in liver (0.08 ± 0.03 μg/g) and kidney (0.08 ± 0.03 μg/g) were similar among all individuals, while both Cu and Zn levels were higher in liver (Cu 9.2 ± 4.5 μg/g; Zn 35.7 ± 3.5 μg/g) than in kidney (Cu 3.7 ± 1.1 μg/g; Zn 21.5 ± 2.7 μg/g). Cu levels also differed between juveniles and adults. We reviewed the literature reporting metal concentrations in beavers. Our results indicate metal contamination in beavers away from important industrial emission sources and suggest the natural environment should be regularly monitored to ensure their levels are below recommended, legal values.

  3. Gross anatomy of the arterial supply of the stomach of the North American beaver (Castor canadensis).

    PubMed

    Bisaillon, A; Bhérer, J

    1979-01-01

    The arterial pattern of the stomach of the North American beaver is studied by dissection of height specimens. The arrangement of the arteries resembles the typical mammalian pattern, although some variations are described. For example, the celiac artery gives off two large vessels, the cardiac and fundic arteries, which supply the corresponding regions of the stomach. Also, the right gastric artery originates from the gastroduodenal vessel instead of the hepatic artery.

  4. Beaver Brook, Keene, New Hampshire. Flood Damage Reduction Project. Detailed Project Report for Water Resources Development.

    DTIC Science & Technology

    1984-02-01

    feet to the upper limit of the urban flood plain around Gif fin Street. Although most of the land in this reach is occupied by the Woodland Cemetery...lands of the Woodland Cemetery and enters the medium to high-density residential neighborhood between Beaver Street and Chiurch Street. Here the...the Gilsum Town Line. A tentative location for the stream gage is in the upper reach of the Woodland Cemetery, downstream of George Street, where a

  5. Geochemical map of the Wet Beaver Roadless Area, Coconino and Yavapai counties, Arizona

    USGS Publications Warehouse

    Gerstel, W.J.

    1985-01-01

    The geochemical survey of the Wet Beaver Roadless Area was conducted in May 1982 by the U.S. Geological Survey to aid in a mineral resource appraisal of the area. A total of 64 stream-sediment samples, 30 heavy-mineral concentrates from stream sediment, 7 rock samples, and 7 water samples was collected by S.C. Rose, D.E. Hendzel, and W.J. Gerstel, with helicopter support from Jack Ruby, pilot for Helicopters Unlimited.

  6. Spatial spread of Eurasian beavers in river networks: a comparison of range expansion rates.

    PubMed

    Barták, Vojtěch; Vorel, Aleš; Símová, Petra; Puš, Vladimír

    2013-05-01

    1. Accurately measuring the rate of spread for expanding populations is important for reliably predicting their future spread, as well as for evaluating the effect of different conditions and management activities on that rate of spread. 2. Although a number of methods have been developed for such measurement, all these are designed only for one- or two-dimensional spread. Species dispersing along rivers, however, require specific methods due to the distinctly branching structure of river networks. 3. In this study, we analyse data regarding Eurasian beavers' modern recolonization of the Czech Republic. We developed a new methodology for quantifying spread of species dispersing along streams based on representation of the river network by means of a weighted graph. 4. We defined two different network-based spread rate measures, one estimating the rate of range expansion, with the range defined as the total length of occupied streams, and the second, named range diameter, quantifying the progress along one or several main streams. In addition, we estimated the population growth rates, and, dividing the population size by the range size, we measured the density of beaver records within their overall range. Using linear regression, we compared four beaver populations under different environmental conditions in terms of each of these measures. Finally, we discuss the differences between our method and the classical approaches. 5. Our method provided substantially higher spread rate values than did the classical methods. Both population growth and range expansion were found to follow logistic growth. In cases of there being no considerable barriers in dispersal routes, the rate of progress along main streams did not differ significantly among populations. In homogeneous environments, population densities remained relatively constant over time even though overall population sizes increased. This indicates that at large spatial scales, the population growth of beavers

  7. Hydrogeology of the Beaver Kill Basin in Sullivan, Delaware, and Ulster Counties, New York

    USGS Publications Warehouse

    Reynolds, Richard J.

    2000-01-01

    The hydrogeology of the 299-square-mile Beaver Kill basin in the southwestern Catskill Mountains of southeastern New York is depicted in a surficial geologic map and five geologic sections, and is summarized through an analysis of low-flow statistics for the Beaver Kill and its major tributary, Willowemoc Creek. Surficial geologic data indicate that the most widespread geologic units within the basin are ablation and lodgment till. Large masses of ablation till as much as 450 feet thick were deposited as lateral embankments within the narrow Beaver Kill and Willowemoc Creek valleys and have displaced the modern stream courses by as much as 1,000 feet from the preglacial bedrock-valley axis.Low-flow statistics for the Beaver Kill and Willowemoc Creeks indicate that the base flows (discharges that are exceeded 90 percent of the time) of these two streams—0.36 and 0.39 cubic feet per square mile,respectively—are the highest of 13 Catskill Mountain streams studied. High base flows elsewhere in the glaciated northeastern United States are generally associated with large stratified-drift aquifers, however, stratified drift in these two basins accounts for only about 5 percent and 4.4 percent of their respective surface areas, respectively. The high base flows in these two basins appear to correlate with an equally high percentage of massive sandstone members of the Catskill Formation, which underlies the entire region. Ground-water seepage from these sandstone members may be responsible for the high base flows of these two streams.

  8. Hydrogeology of the Beaver Kill basin in Sullivan, Delaware, and Ulster Counties, New York

    USGS Publications Warehouse

    Reynolds, Richard J.

    2000-01-01

    The hydrogeology of the 299-square-mile Beaver Kill basin in the southwestern Catskill Mountains of southeastern New York is depicted in a surficial geologic map and five geologic sections, and is summarized through an analysis of low-flow statistics for the Beaver Kill and its major tributary, Willowemoc Creek. Surficial geologic data indicate that the most widespread geologic units within the basin are ablation and lodgment till. Large masses of ablation till as much as 450 feet thick were deposited as lateral embankments within the narrow Beaver Kill and Willowemoc Creek valleys and have displaced the modern stream courses by as much as 1,000 feet from the preglacial bedrock-valley axis. Low-flow statistics for the Beaver Kill and Willowemoc Creeks indicate that the base flows (discharges that are exceeded 90 percent of the time) of these two streams--0.36 and 0.39 cubic feet per square mile,respectively--are the highest of 13 Catskill Mountain streams studied. High base flows elsewhere in the glaciated northeastern United States are generally associated with large stratified-drift aquifers, however, stratified drift in these two basins accounts for only about 5 percent and 4.4 percent of their respective surface areas, respectively. The high base flows in these two basins appear to correlate with an equally high percentage of massive sandstone members of the Catskill Formation, which underlies the entire region. Ground-water seepage from these sandstone members may be responsible for the high base flows of these two streams.

  9. Do transmitters affect survival and body condition of American beavers Castor canadensis?

    USGS Publications Warehouse

    Smith, Joshua B.; Windels, Steve K.; Wolf, Tiffany; Klaver, Robert W.; Belant, Jerrold L.

    2016-01-01

    One key assumption often inferred with using radio-equipped individuals is that the transmitter has no effect on the metric of interest. To evaluate this assumption, we used a known fate model to assess the effect of transmitter type (i.e. tail-mounted or peritoneal implant) on short-term (one year) survival and a joint live—dead recovery model and results from a mark—recapture study to compare long-term (eight years) survival and body condition of ear-tagged only American beavers Castor canadensis to those equipped with radio transmitters in Voyageurs National Park, Minnesota, USA. Short-term (1-year) survival was not influenced by transmitter type (wi = 0.64). Over the 8-year study period, annual survival was similar between transmitter-equipped beavers (tail-mounted and implant transmitters combined; 0.76; 95% CI = 0.45–0.91) versus ear-tagged only (0.78; 95% CI = 0.45–0.93). Additionally, we found no difference in weight gain (t9 = 0.25, p = 0.80) or tail area (t11 = 1.25, p = 0.24) from spring to summer between the two groups. In contrast, winter weight loss (t22 = - 2.03, p = 0.05) and tail area decrease (t30 = - 3.04, p = 0.01) was greater for transmitterequipped (weight = - 3.09 kg, SE = 0.55; tail area = - 33.71 cm2, SE = 4.80) than ear-tagged only (weight = - 1.80 kg, SE = 0.33; tail area = - 12.38 cm2, SE = 5.13) beavers. Our results generally support the continued use of transmitters on beavers for estimating demographic parameters, although we recommend additional assessments of transmitter effects under different environmental conditions.

  10. Aeromagnetic map of the Wet Beaver Roadless Area, Yavapai and Coconino counties, Arizona

    USGS Publications Warehouse

    Martin, R.A.

    1986-01-01

    The western boundary of the roadless area and the mouth of Wet Beaver Creek canyon are accessible by Forest Service roads from either Camp Verde or the Sedona interchange on Interstate Highway 17. Various points along the canyon rim and the area boundary can be reached by unimproved roads, jeep trails, and pack trails. The canyon floor is accessible only on foot; in several places, deep pools require a swim or steep climb and descent for traverse of the canyon.

  11. Fast Reactors

    NASA Astrophysics Data System (ADS)

    Esposito, S.; Pisanti, O.

    The following sections are included: * Elementary Considerations * The Integral Equation to the Neutron Distribution * The Critical Size for a Fast Reactor * Supercritical Reactors * Problems and Exercises

  12. Beaver impoundments in temperate forests as sources of atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Yavitt, Joseph B.; Fahey, Timothy J.

    1994-06-01

    Beaver impoundments trap large amounts of organic matter, and remineralization of the organic matter to CO2 could make them a significant source of atmospheric CO2. Measurements in two beaver impoundments in the Adirondack Park of New York State indicated that: (i) during the ice-free season CO2 emission averaged 197 mmol m-2d-1 (ii) concentrations of dissolved inorganic carbon (DIC) in the water column were always >100 µM, reaching >1000 µM beneath ice cover and in midsummer; and (iii) the rate of CO2 production by sediment samples from beneath the water column could exceed 300 mmol m-2d-1 in midsummer. The CO2 emitted from the impoundments to the atmosphere is supplied both by the sediments beneath the impoundment and by transport into the water column from the surrounding uplands. If beaver impoundments cover 3% of the landscape in north temperate forests then the magnitude of the presumed CO2 sink in this landscape would be reduced by 7% compared with estimates based only on the terrestrial component.

  13. Parameterization of the ACRU model for estimating biophysical and climatological change impacts, Beaver Creek, Alberta

    NASA Astrophysics Data System (ADS)

    Forbes, K. A.; Kienzle, S. W.; Coburn, C. A.; Byrne, J. M.

    2006-12-01

    Multiple threats, including intensification of agricultural production, non-renewable resource extraction and climate change, are threatening Southern Alberta's water supply. The objective of this research is to calibrate/evaluate the Agricultural Catchments Research Unit (ACRU) agrohydrological model; with the end goal of forecasting the impacts of a changing environment on water quantity. The strength of this model is the intensive multi-layered soil water budgeting routine that integrates water movement between the surface and atmosphere. The ACRU model was parameterized using data from Environment Canada's climate database for a twenty year period (1984-2004) and was used to simulate streamflow for Beaver Creek. The simulated streamflow was compared to Environment Canada's historical streamflow database to validate the model output. The Beaver Creek Watershed, located in the Porcupine Hills southwestern Alberta, Canada contains a heterogeneous cover of deciduous, coniferous, native prairie grasslands and forage crops. In a catchment with highly diversified land cover, canopy architecture cannot be overlooked in rainfall interception parameterization. Preliminary testing of ACRU suggests that streamflows were sensitive to varied levels of leaf area index (LAI), a representative fraction of canopy foliage. Further testing using remotely sensed LAI's will provide a more accurate representation of canopy foliage and ultimately best represent this important element of the hydrological cycle and the associated processes which govern the natural hydrology of the Beaver Creek watershed.

  14. Beaver (Castor canadensis) responses to major phenolic and neutral compounds in castoreum.

    PubMed

    Schulte, B A; Müller-Schwarze, D; Tang, R; Webster, F X

    1994-12-01

    North American beaver (Castor canadensis) mark their territories with castoreum, a chemically complex secretion from their castor sacs. The phenolic and neutral fractions of castoreum have been shown to elicit specific behavioral responses from beavers in a field setting. Our objective was to identify compounds/mixtures that evoked responses similar to those stimulated by castoreum. We assayed recently identified phenolic compounds, some phenolics that had been determined to be biologically active in previous studies, the neutral compound borneol, and combinations of phenolic compounds, neutral compounds, and the two combined. Biological activity was measured by the elicitation and extent of specific responses and their strength (duration, frequency, and proportion of beavers responding). Generally, single compounds stimulated fewer responses than mixtures. A 26-compound mixture of phenolic and neutral compounds elicited responses in a similar proportion of trials as castoreum. However, responses to castoreum were stronger than to any synthetic sample. Further investigation of different measures of response, namely, elicitation, completeness, and strength, are deemed necessary to fully decipher the design of social odors.

  15. Habitat Evaluation Procedures (HEP) Report : West Beaver Lake, 2004-2005 Technical Report.

    SciTech Connect

    Entz, Ray

    2005-02-01

    On September 7, 2004, the Habitat Evaluation Procedure (HEP) was used to determine baseline habitat suitability on the West Beaver Lake property, an acquisition completed by the Kalispel Tribe of Indians in September 2004. Evaluation species and appropriate models include bald eagle, black-capped chickadee, mallard, muskrat, and white-tailed deer. Habitat Suitability Index (HSI) values were visually estimated and agreed upon by all HEP team members. The West Beaver Lake Project provides a total of 103.08 Habitat Units (HUs) for the species evaluated. Emergent wetland habitat provides 7.17 HUs for mallard and muskrat. Conifer forest habitat provides 95.91 HUs for bald eagle, black-capped chickadee, mallard, and white-tailed deer. The objective of using HEP at the West Beaver Lake Project and other protected properties is to document the quality and quantity of available habitat for selected wildlife species. In this way, HEP provides information on the relative value of the same area at future points in time so that the effect of management activities on wildlife habitat can be quantified. When combined with other tools, the baseline HEP will be used to determine the most effective on-site management, restoration, and enhancement actions to increase habitat suitability for targeted species. The same process will be replicated every five years to quantitatively evaluate the effectiveness of management strategies in improving and maintaining habitat conditions while providing additional crediting to BPA for enhanced habitat values.

  16. A novel papillomavirus isolated from proliferative skin lesions of a wild American beaver (Castor canadensis).

    PubMed

    Rogovskyy, Artem S; Baszler, Timothy V; Bradway, Daniel S; Bruning, Darren L; Davitt, Christine M; Evermann, James F; Burk, Robert D; Chen, Zigui; Mansfield, Kristin G; Haldorson, Gary J

    2012-07-01

    Cutaneous papillomatosis was diagnosed in an adult American beaver (Castor canadensis). Gross lesions included numerous exophytic, roughly circular, lightly pigmented lesions on hairless areas of fore and hind feet and the nose. The most significant histopathologic findings were multifocal papilliform hyperplasia of the superficial stratified squamous epithelium, with multifocal koilocytes, and multiple cells with large, darkly basophilic intranuclear inclusion bodies. A virus with properties consistent with papillomavirus (PV) was recovered by virus isolation of skin lesions, utilizing rabbit and feline kidney cell lines. The presence of the virus was confirmed by PV-specific polymerase chain reaction. The partial sequences of E1 and L1 genes did not closely match those of any PVs in GenBank, suggesting that this might be a new type of PV. Partial E1 and L1 nucleotide sequences of the beaver papillomavirus (hereafter, ARbeaver-PV1) were used to create a phylogenetic tree employing the complete E1 and L1 open reading frame nucleotide sequences of 68 PVs. The phylogenetic tree placed the ARbeaver-PV1 in a clade that included the Mupapillomavirus (HPV1 and HPV63) and Kappapapillomavirus (OcPV1 and SfPV1) genera. The present article confirms the papillomaviral etiology of cutaneous exophytic lesions in the beaver.

  17. Using Seismic Refraction and Ground Penetrating Radar (GPR) to Characterize the Valley Fill in Beaver Meadows, Rocky Mountain National Park

    NASA Astrophysics Data System (ADS)

    Kramer, N.; Harry, D. L.; Wohl, E. E.

    2010-12-01

    This study is one of the first to use near surface geophysical techniques to characterize the subsurface stratigraphy in a high alpine, low gradient valley with a past glacial history and to obtain a preliminary grasp on the impact of Holocene beaver activity. Approximately 1 km of seismic refraction data and 5 km of GPR data were collected in Beaver Meadows, Rocky Mountain National Park. An asymmetric wedge of sediment ranging in depth from 0-20 m transverse to the valley profile was identified using seismic refraction. Complementary analysis of the GPR data suggests that the valley fill can be subdivided into till deposited during the Pleistocene glaciations and alluvium deposited during the Holocene. Two main facies were identified in the GPR profiles through pattern recognition. Facie Fd, which consists of chaotic discontinuous reflectors with an abundance of diffractions, is interpreted to be glacial till. Facie Fc, which is a combination of packages of complex slightly continuous reflectors interfingered with continuous horizontal to subhorizontal reflectors, is interpreted to be post-glacial alluvium and includes overbank, pond and in-channel deposits. Fc consistently overlies Fd throughout the study area and is no more than 7 m thick in the middle of the valley. The thickness of Holocene sedimentation (<7 m) is much less than the total amount of valley fill identified in the seismic refraction survey (0-20 m). A subfacie of Fc, Fch, which has reflectors with long periods was identified within Fc and is interpreted to be ponded sediments. The spatial distribution of facie Fch, along with: slight topographical features resembling buried beaver dams, a high abundance of fine sediment including silts and clays, historical records of beavers, and the name "Beaver Meadows" all suggest that Holocene beaver activity played a large role in sediment accumulation at this site, despite the lack of surficial relict beaver dams containing wood.

  18. Fluvial wood function downstream of beaver versus man-made dams in headwater streams in Massachusetts, USA

    NASA Astrophysics Data System (ADS)

    David, G. C.; DeVito, L. F.; Munz, K. T.; Lisius, G.

    2014-12-01

    Fluvial wood is an essential component of stream ecosystems by providing habitat, increasing accumulation of organic matter, and increasing the processing of nutrients and other materials. However, years of channel alterations in Massachusetts have resulted in low wood loads despite the afforestation that has occurred since the early 1900s. Streams have also been impacted by a large density of dams, built during industrialization, and reduction of the beaver population. Beavers were reintroduced to Massachusetts in the 1940s and they have since migrated throughout the state. Beaver dams impound water, which traps sediment and results in the development of complex channel patterns and more ecologically productive and diverse habitats than those found adjacent to man-made dams. To develop better management practices for dam removal it is essential that we understand the geomorphic and ecologic function of wood in these channels and the interconnections with floodplain dynamics and stream water chemistry. We investigate the connections among fluvial wood, channel morphology, floodplain soil moisture dynamics, and stream water chemistry in six watersheds in Massachusetts that have been impacted by either beaver or man-made dams. We hypothesize that wood load will be significantly higher below beaver dams, subsequently altering channel morphology, water chemistry, and floodplain soil moisture. Reaches are surveyed up- and downstream of each type of dam to better understand the impact dams have on the fluvial system. Surveys include a longitudinal profile, paired with dissolved oxygen and ammonium measurements, cross-section and fluvial wood surveys, hydraulic measurements, and floodplain soil moisture mapping. We found that dissolved oxygen mirrored the channel morphology, but did not vary significantly between reaches. Wood loads were significantly larger downstream of beaver dams, which resulted in significant changes to the ammonium levels. Floodplain soil moisture

  19. Beaver dams, hydrological thresholds, and controlled floods as a management tool in a desert riverine ecosystem, Bill Williams River, Arizona

    USGS Publications Warehouse

    Andersen, D.C.; Shafroth, P.B.

    2010-01-01

    Beaver convert lotic stream habitat to lentic through dam construction, and the process is reversed when a flood or other event causes dam failure. We investigated both processes on a regulated Sonoran Desert stream, using the criterion that average current velocity is < 0.2 m s-1 in a lentic reach. We estimated temporal change in the lotic:lentic stream length ratio by relating beaver pond length (determined by the upstream lentic-lotic boundary position) to dam size, and coupling that to the dam-size frequency distribution and repeated censuses of dams along the 58-km river. The ratio fell from 19:1 when no beaver dams were present to < 3:1 after 7 years of flows favourable for beaver. We investigated the dam failure-flood intensity relationship in three independent trials (experimental floods) featuring peak discharge ranging from 37 to 65 m3 s-1. Major damage (breach ??? 3-m wide) occurred at ??? 20% of monitored dams (n = 7-86) and a similar or higher proportion was moderately damaged. We detected neither a relationship between dam size and damage level nor a flood discharge threshold for initiating major damage. Dam constituent materials appeared to control the probability of major damage at low (attenuated) flood magnitude. We conclude that environmental flows prescribed to sustain desert riparian forest will also reduce beaver-created lentic habitat in a non-linear manner determined by both beaver dam and flood attributes. Consideration of both desirable and undesirable consequences of ecological engineering by beaver is important when optimizing environmental flows to meet ecological and socioeconomic goals. ?? 2010 John Wiley & Sons, Ltd.

  20. NEUTRONIC REACTOR

    DOEpatents

    Fermi, E.; Zinn, W.H.; Anderson, H.L.

    1958-09-16

    Means are presenied for increasing the reproduction ratio of a gaphite- moderated neutronic reactor by diminishing the neutron loss due to absorption or capture by gaseous impurities within the reactor. This means comprised of a fluid-tight casing or envelope completely enclosing the reactor and provided with a valve through which the casing, and thereby the reactor, may be evacuated of atmospheric air.

  1. The Use of Acceleration to Code for Animal Behaviours; A Case Study in Free-Ranging Eurasian Beavers Castor fiber.

    PubMed

    Graf, Patricia M; Wilson, Rory P; Qasem, Lama; Hackländer, Klaus; Rosell, Frank

    2015-01-01

    Recent technological innovations have led to the development of miniature, accelerometer-containing electronic loggers which can be attached to free-living animals. Accelerometers provide information on both body posture and dynamism which can be used as descriptors to define behaviour. We deployed tri-axial accelerometer loggers on 12 free-ranging Eurasian beavers Castor fiber in the county of Telemark, Norway, and on four captive beavers (two Eurasian beavers and two North American beavers C. canadensis) to corroborate acceleration signals with observed behaviours. By using random forests for classifying behavioural patterns of beavers from accelerometry data, we were able to distinguish seven behaviours; standing, walking, swimming, feeding, grooming, diving and sleeping. We show how to apply the use of acceleration to determine behaviour, and emphasise the ease with which this non-invasive method can be implemented. Furthermore, we discuss the strengths and weaknesses of this, and the implementation of accelerometry on animals, illustrating limitations, suggestions and solutions. Ultimately, this approach may also serve as a template facilitating studies on other animals with similar locomotor modes and deliver new insights into hitherto unknown aspects of behavioural ecology.

  2. Genetic characterisation of Toxoplasma gondii isolates from European beavers (Castor fiber) and European wildcats (Felis silvestris silvestris).

    PubMed

    Herrmann, D C; Wibbelt, G; Götz, M; Conraths, F J; Schares, G

    2013-01-16

    Six free-ranging European beavers (Castor fiber) from Berlin greater metropolitan area and twelve European wildcats (Felis silvestris silvestris) originating from the German Federal State of Saxony-Anhalt were found dead and their carcasses were submitted for necropsy. Brain and lung samples were analysed for the presence of Toxoplasma gondii DNA. Histo-pathologic analysis of one beaver revealed several cyst-like protozoal structures in parts of the brain. Tissue DNA isolated from all animal samples was analysed by a specific T. gondii-PCR. Two beavers and four wildcats tested T. gondii-positive. DNA of the parasites was further analysed by PCR-RFLP typing using nine markers (nSAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1 and Apico). Only T. gondii type II alleles were detected, except for the Apico locus, where type I alleles were observed in two isolates from beavers and in three from wild cats. The results of this study indicate that type II T. gondii (including type II variant strain) is the most common genotype infecting wildcats and beavers from Germany.

  3. The Use of Acceleration to Code for Animal Behaviours; A Case Study in Free-Ranging Eurasian Beavers Castor fiber

    PubMed Central

    Graf, Patricia M.; Wilson, Rory P.; Qasem, Lama; Hackländer, Klaus; Rosell, Frank

    2015-01-01

    Recent technological innovations have led to the development of miniature, accelerometer-containing electronic loggers which can be attached to free-living animals. Accelerometers provide information on both body posture and dynamism which can be used as descriptors to define behaviour. We deployed tri-axial accelerometer loggers on 12 free-ranging Eurasian beavers Castor fiber in the county of Telemark, Norway, and on four captive beavers (two Eurasian beavers and two North American beavers C. canadensis) to corroborate acceleration signals with observed behaviours. By using random forests for classifying behavioural patterns of beavers from accelerometry data, we were able to distinguish seven behaviours; standing, walking, swimming, feeding, grooming, diving and sleeping. We show how to apply the use of acceleration to determine behaviour, and emphasise the ease with which this non-invasive method can be implemented. Furthermore, we discuss the strengths and weaknesses of this, and the implementation of accelerometry on animals, illustrating limitations, suggestions and solutions. Ultimately, this approach may also serve as a template facilitating studies on other animals with similar locomotor modes and deliver new insights into hitherto unknown aspects of behavioural ecology. PMID:26317623

  4. Fatty acids in extremity tissues of Finnish beavers (Castor canadensis and Castor fiber) and muskrats (Ondatra zibethicus).

    PubMed

    Käkelä, R; Hyvärinen, H

    1996-01-01

    Site-specific differences in fatty acid composition of adipose tissues from Finnish beavers (Castor canadensis and Castor fiber) and muskrats (Ondatra zibethicus) were studied by gas liquid chromatography. In the total lipids of heterothermic extremities the proportions of potentially endogenous (delta 9-desaturated) monoenoic fatty acids were 1.5-fold and those of the saturated fatty acids 0.5-fold the proportions of subcutaneous or inner depots. Thus the role of delta 9-desaturation in the biochemical adaptation of the extremity tissues is discussed. Dietary polyunsaturated fatty acids, with the exception of 18:3 omega 3 in the beavers, did not accumulate selectively in the extremity tissues. The liver of the muskrat (which also eats fish and mussels) contained high proportions of 22:6 omega 3, which was a minor component in the beaver (exclusively a herbivore).

  5. Effects of a beaver pond on runoff processes: comparison of two headwater catchments

    USGS Publications Warehouse

    Burns, Douglas A.; McDonnell, Jeffery J.

    1998-01-01

    Natural variations in concentrations of 18O, D, and H4SiO4 in two tributary catchments of Woods Lake in the west-central Adirondack Mountains of New York were measured during 1989–1991 to examine runoff processes and their implications for the neutralization of acidic precipitation by calcium carbonate treatment. The two catchments are similar except that one contained a 1.3 ha beaver pond. Evaporation from the beaver pond caused a seasonal decrease in the slope of the meteoric water line in stream water from the catchment with a beaver pond (WO2). No corresponding change in slope of the meteoric water line was evident in stream water from the other catchment (WO4), nor in ground water nor soil water from either catchment, indicating that evaporative fractionation was not significant. Application of a best-fit sine curve to δ18O data indicated that base flow in both catchments had a residence time of about 100 days. Ground water from a well finished in thick till had the longest residence time (160 days); soil water from the O-horizon and B-horizon had residence times of 63 and 80 days, respectively. Water previously stored within each catchment (pre-event water) was the predominant component of streamflow during spring snowmelt and during spring and autumn rainfall events, but the proportion of streamflow that consisted of pre-event water differed significantly in the two catchments. The proportion of event water (rain and snowmelt) in WO2 was smaller than at WO4 early in the spring snowmelt of March 13–17, 1990, but the proportions of source water components for the two catchments were almost indistinguishable by the peak flow on the third day of the melt. The event water was further separated into surface-water and subsurface-water components by utilizing measured changes in H4SiO4 concentrations in stream water during the snowmelt. Results indicated that subsurface flow was the dominant pathway by which event water reached the stream except during the

  6. Measuring Taste Impairment in Epidemiologic Studies – The Beaver Dam Offspring Study

    PubMed Central

    Cruickshanks, KJ; Schubert, CR; Snyder, DJ; Bartoshuk, LM; Huang, GH; Klein, BEK; Klein, R; Nieto, FJ; Pankow, JS; Tweed, TS; Krantz, EM; Moy, GS

    2008-01-01

    Taste or gustatory function may play an important role in determining diet and nutritional status and therefore indirectly impact health. Yet there have been few attempts to study the spectrum of taste function and dysfunction in human populations. Epidemiological studies are needed to understand the impact of taste function and dysfunction on public health, to identify modifiable risk factors, and to develop and test strategies to prevent clinically significant dysfunction. However, measuring taste function in epidemiological studies is challenging and requires repeatable, efficient methods which can measure change over time. Insights gained from translating laboratory-based methods to a population-based study, the Beaver Dam Offspring Study (BOSS) will be shared. In this study, a generalized labeled magnitude scale (gLMS) method was used to measure taste intensity of filter paper disks saturated with salt, sucrose, citric acid, quinine, or 6-n-propylthiouracil and a gLMS measure of taste preferences was administered. In addition, a portable, inexpensive camera system to capture digital images of fungiform papillae and a masked grading system to measure the density of fungiform papillae were developed. Adult children of participants in the population-based Epidemiology of Hearing Loss Study in Beaver Dam, Wisconsin are eligible for this on-going study. The parents were residents of Beaver Dam and 43–84 years of age in 1987–88; offspring range in age from 21–84 years in 2005–2008. Methods will be described in detail and preliminary results about the distributions of taste function in the BOSS cohort will be presented. PMID:19686191

  7. Habitat Evaluation Procedures (HEP) Report; West Beaver Lake Project, Technical Report 2005

    SciTech Connect

    Entz, Ray

    2005-05-01

    On September 7, 2004, the Habitat Evaluation Procedure (HEP) was used to determine baseline habitat suitability on the West Beaver Lake property, an acquisition completed by the Kalispel Tribe of Indians in September 2004. Evaluation species and appropriate models include bald eagle, black-capped chickadee, mallard, muskrat, and white-tailed deer. Habitat Suitability Index (HSI) values were visually estimated and agreed upon by all HEP team members. The West Beaver Lake Project provides a total of 82.69 Habitat Units (HUs) for the species evaluated. Emergent wetland habitat provides 8.80 HUs for mallard, muskrat, and Canada goose. Conifer forest habitat provides 70.33 HUs for bald eagle, black-capped chickadee, mallard, and white-tailed deer. Open water provides 3.30 HUs for mallard, muskrat, and Canada goose. The objective of using HEP at the West Beaver Lake Project and other protected properties is to document the quality and quantity of available habitat for selected wildlife species. In this way, HEP provides information on the relative value of the same area at future points in time so that the effect of management activities on wildlife habitat can be quantified. When combined with other tools, the baseline HEP will be used to determine the most effective on-site management, restoration, and enhancement actions to increase habitat suitability for targeted species. The same process will be replicated every five years to quantitatively evaluate the effectiveness of management strategies in improving and maintaining habitat conditions while providing additional crediting to BPA for enhanced habitat values.

  8. Sexual dimorphism in territorial scent marking by adult Eurasian beavers (Castor fiber).

    PubMed

    Rosell, Frank; Thomsen, Liat R

    2006-06-01

    Mammalian scent marking is often associated with territorial defense. However, males and females may demonstrate different activity patterns and play different roles. Female mammals nurture the young during lactation, while males purportedly perform other tasks more frequently, such as territorial maintenance and defense. This paper investigates the contribution made by mated pairs of adult males and females to territorial scent-marking in the obligate monogamous Eurasian beavers (Castor fiber). We hypothesized that both sexes should show territorial behavior, and predicted that they deposit a higher proportion of scent marks at borders. We also hypothesized that a sexual dimorphism exists due to reproductive constraints on the females, and predicted that males should invest significantly more in scent-marking behavior than females during summer. We obtained behavioral data by radio tracking six mated pairs of Eurasian beavers during spring and summer 2000-2001 on two rivers in southeastern Norway. Our results showed that both males and females clustered their scent marks near territorial borders, but males deposited a larger number of scent marks than females and spent more time at borders. Males were also found to have a higher scent marking rate and scent marks per night than females during summer, but not during spring. Overall, scent marks per night were higher in males than females. We conclude that both males and females Eurasian beavers carry out territorial behavior by scent marking, but males carry a larger part of the territorial defense during summer when females lactate. Our results are discussed in the light of the codefense hypothesis.

  9. Simulation of hydrodynamics, temperature, and dissolved oxygen in Beaver Lake, Arkansas, 1994-1995

    USGS Publications Warehouse

    Haggard, Brian; Green, W. Reed

    2002-01-01

    The tailwaters of Beaver Lake and other White River reservoirs support a cold-water trout fishery of significant economic yield in northwestern Arkansas. The Arkansas Game and Fish Commission has requested an increase in existing minimum flows through the Beaver Lake dam to increase the amount of fishable waters downstream. Information is needed to assess the impact of additional minimum flows on temperature and dissolved-oxygen qualities of reservoir water above the dam and the release water. A two-dimensional, laterally averaged hydrodynamic, thermal and dissolved-oxygen model was developed and calibrated for Beaver Lake, Arkansas. The model simulates surface-water elevation, currents, heat transport and dissolved-oxygen dynamics. The model was developed to assess the impacts of proposed increases in minimum flows from 1.76 cubic meters per second (the existing minimum flow) to 3.85 cubic meters per second (the additional minimum flow). Simulations included assessing (1) the impact of additional minimum flows on tailwater temperature and dissolved-oxygen quality and (2) increasing initial water-surface elevation 0.5 meter and assessing the impact of additional minimum flow on tailwater temperatures and dissolved-oxygen concentrations. The additional minimum flow simulation (without increasing initial pool elevation) appeared to increase the water temperature (<0.9 degrees Celsius) and decrease dissolved oxygen concentration (<2.2 milligrams per liter) in the outflow discharge. Conversely, the additional minimum flow plus initial increase in pool elevation (0.5 meter) simulation appeared to decrease outflow water temperature (0.5 degrees Celsius) and increase dissolved oxygen concentration (<1.2 milligrams per liter) through time. However, results from both minimum flow scenarios for both water temperature and dissolved oxygen concentration were within the boundaries or similar to the error between measured and simulated water column profile values.

  10. Collection of short papers on Beaver Creek watershed studies in West Tennessee, 1989-94

    USGS Publications Warehouse

    Doyle, W. Harry.; Baker, Eva G.

    1995-01-01

    In 1989, the U.S. Geological Survey began a scientific investigation to evaluate the effect of agricultural activities on water quality and the effectiveness of agricultural best management practices in the Beaver Creek watershed, West Tennessee. The project is being conducted jointly with other Federal, State, county agencies, the farming community, and academic institutions, in support of the U.S. Department of Agriculture's Hydrologic Unit Area program. The Beaver Creek project has evolved into a long-term watershed assessment and monitoring program. In 1991, a grant was received to develop and evaluate sampling strategies for higher order streams. During the summer of 1992, a reconnaissance of water-quality conditions for the shallow aquifers in Shelby, Tipton, Fayette, and Haywood Counties was conducted and included 89 domestic wells in the Beaver Creek watershed. Results from this effort lead to the development of a 1-year program to evaluate cause- and-effect relations that can explain the observed water-quality conditions for the shallow aquifers in the watershed. In 1992 the USGS, in cooperation with the Soil Conservation Service and the Shelby County Soil Conservation District, began an evaluation of in-stream processes and in-stream resource-management systems. In 1993, a biomonitoring program was established in the watershed. This collection of eight articles and abstracts was originally published in the American Water Resources Association National Symposium on Water Quality Proceedings for the national conference held in Chicago in 1994 and describes what has been learned in the study to date.

  11. 77 FR 34297 - Approval and Promulgation of Air Quality Implementation Plans; Pennsylvania; Pittsburgh-Beaver...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-11

    ....8 10.8 11.7 Allegheny 42-003-0093 North Park 13.0 (*) 9.6 11.3 Allegheny 42-003-0095 Moon 13.6 (*) 9....8 11.7 11.1 Allegheny 42-003-0093 North Park (*) 9.6 10.5 10.1 Allegheny 42-003-0095 Moon (*) 9.4 11...-0095 Moon ** Allegheny 42-003-1008 Harrison *11.6 Allegheny 42-003-1301 North Braddock *12.3 Beaver 42...

  12. Beaver impoundments in temperate forests as sources of atmospheric CO{sub 2}

    SciTech Connect

    Yavitt, Y.B.; Fahey, T.J.

    1994-06-01

    The authors report on measurements of carbon dioxide fluxes from two beaver ponds in the Adirondacks in New York. They measured emissions of carbon dioxide on ice free days, concentrations of dissolved organic carbon in the water, both with and without ice cover, and estimated carbon dioxide production rates from sediments below the water column. The CO{sub 2} emitted from the ponds comes both from release from pond components, and from flow in from the drainage area. Their results show that the ponds are a significantly more intense source of CO{sub 2}, than the corresponding land surface areas.

  13. Constituent concentrations, loads, and yields to Beaver Lake, Arkansas, water years 1999-2008

    USGS Publications Warehouse

    Bolyard, Susan E.; De Lanois, Jeanne L.; Green, W. Reed

    2010-01-01

    Beaver Lake is a large, deep-storage reservoir used as a drinking-water supply and considered a primary watershed of concern in the State of Arkansas. As such, information is needed to assess water quality, especially nutrient enrichment, nutrient-algal relations, turbidity, and sediment issues within the reservoir system. Water-quality samples were collected at three main inflows to Beaver Lake: the White River near Fayetteville, Richland Creek at Goshen, and War Eagle Creek near Hindsville. Water-quality samples collected over the period represented different flow conditions (from low to high). Constituent concentrations, flow-weighted concentrations, loads, and yields from White River, Richland Creek, and War Eagle Creek to Beaver Lake for water years 1999-2008 were documented for this report. Constituents include total ammonia plus organic nitrogen, dissolved nitrite plus nitrate nitrogen, dissolved orthophosphorus (soluble reactive phosphorus), total phosphorus, total nitrogen, dissolved organic carbon, total organic carbon, and suspended sediment. Linear regression models developed by computer program S-LOADEST were used to estimate loads for each constituent for the 10-year period at each station. Constituent yields and flow-weighted concentrations for each of the three stations were calculated for the study. Constituent concentrations and loads and yields varied with time and varied among the three tributaries contributing to Beaver Lake. These differences can result from differences in precipitation, land use, contributions of nutrients from point sources, and variations in basin size. Load and yield estimates varied yearly during the study period, water years 1999-2008, with the least nutrient and sediment load and yields generally occurring in water year 2006, and the greatest occurring in water year 2008, during a year with record amounts of precipitation. Flow-weighted concentrations of most constituents were greatest at War Eagle Creek near Hindsville

  14. Decoupling the Stationary Navier-Stokes-Darcy System with the Beavers-Joseph-Saffman Interface Condition

    DOE PAGES

    Cao, Yong; Chu, Yuchuan; He, Xiaoming; ...

    2013-01-01

    This paper proposes a domain decomposition method for the coupled stationary Navier-Stokes and Darcy equations with the Beavers-Joseph-Saffman interface condition in order to improve the efficiency of the finite element method. The physical interface conditions are directly utilized to construct the boundary conditions on the interface and then decouple the Navier-Stokes and Darcy equations. Newton iteration will be used to deal with the nonlinear systems. Numerical results are presented to illustrate the features of the proposed method.

  15. Practical aspects of registration the transformation of a river valley by beavers using terrestrial laser scanning

    NASA Astrophysics Data System (ADS)

    Tyszkowski, Sebastian; Błaszkiewicz, Mirosław; Brykała, Dariusz; Gierszewski, Piotr; Kaczmarek, Halina; Kordowski, Jarosław; Słowiński, Michał

    2016-04-01

    Activity of beavers (Castor fiber) often significantly affects the environment in which they life. The most commonly observed effect of their being in environment is construction of beaver dams and formation a pond upstream. However, in case of a sudden break of a dam and beaver pond drainage, the valley below the dam may also undergo remodelling. The nature and magnitude of these changes depends on the quantity of water and its energy as well as on the geological structure of the valley. The effects of such events can be riverbank erosion, and the deposition of the displaced of erosion products in the form of sandbars or fans. The material can also be accumulated in local depressions or delivered to water bodies. Such events may occur multiple times in the same area. To assess their impact on the environment it is important to quantify the displaced material. The study of such transformations was performed within a small valley of the river of Struga Czechowska (Tuchola Pinewood Forest, Poland). The valley is mainly cut in sands and gravels. Its steep banks are overgrown with bushes and trees. The assessment of changes in morphology were based on the event of the beaver pond drainage of 2015. The study uses the measurements from the terrestrial laser scanning (scanner Riegl VZ-4000). The measurements were performed before and after the event. Each of the two models obtained for comparison was made up of more than 20 measurement stations. Point clouds were joined by Multi-Station Adjustment without placing in the terrain any objects of reference. During measurements attention was paid to the changes in morphology of both riverbed and valley surrounding. The paper presents the example of the recorded changes as well as the measurement procedure. Moreover, the aspects of fieldwork and issues related to post-processing, such as merging, filtering of point clouds and detection of changes, are also presented. This study is a contribution to the Virtual Institute of

  16. Depositional Model for a Beaver Pond Complex in a Piedmont Stream Valley

    NASA Astrophysics Data System (ADS)

    Rachide, S. P.; Diemer, J. A.

    2016-12-01

    The North American beaver (Castor canadensis) often construct closely-spaced ponds on suitable sections of streams. Over time avulsive processes form an intricate network of shallow anabranching streams that connect a multitude of ponds, referred to here as a beaver pond complex (BPC). According to Polvi and Wohl (2012), BPCs evolve through four stages. Their model, resulting from the study of an alpine stream dominated by meltwater, focused on changes in valley planform, increased channel complexity, and the effects of floodplain sediment storage during the growth of a BPC. A revised depositional model for a multi-generation BPC is presented here, based on data collected at Mill Creek, in the Piedmont of North Carolina. The field data, comprising geolocated maps, cores and probes, were collected between March 2011 and October 2014 and were supplemented by 12 aerial images of the field area taken from January 1993 to October 2014. The revised BPC depositional model comprises several stages of development that include initial beaver occupation, followed by an interval of fast-paced pond creation and increasing channel complexity, a stage of slowing growth of the BPC, followed by cycles of dam breaching and repair, and an abandonment phase. An additional stage may include later reoccupation of an abandoned BPC to produce a multi-generation BPC. The areas affected by, and durations of, these stages are likely dictated by several variables including: geologic controls, local climate, hydrologic regime, beaver population size, and resource availability. Rare large precipitation events that led to the breaching of dams were likely the most impactful variable in the evolution of the Mill Creek BPC. Field observations indicate that beaching events affected the Mill Creek BPC more frequently than could be inferred from the 12 aerial images of the site. Therefore, aerial imagery should be used in conjunction with field-based investigations in order to more accurately

  17. BOILING REACTORS

    DOEpatents

    Untermyer, S.

    1962-04-10

    A boiling reactor having a reactivity which is reduced by an increase in the volume of vaporized coolant therein is described. In this system unvaporized liquid coolant is extracted from the reactor, heat is extracted therefrom, and it is returned to the reactor as sub-cooled liquid coolant. This reduces a portion of the coolant which includes vaporized coolant within the core assembly thereby enhancing the power output of the assembly and rendering the reactor substantially self-regulating. (AEC)

  18. NEUTRONIC REACTOR

    DOEpatents

    Daniels, F.

    1959-10-27

    A reactor in which at least a portion of the moderator is in the form of movable refractory balls is described. In addition to their moderating capacity, these balls may serve as carriers for fissionable material or fertile material, or may serve in a coolant capacity to remove heat from the reactor. A pneumatic system is used to circulate the balls through the reactor.

  19. NUCLEAR REACTOR

    DOEpatents

    Treshow, M.

    1961-09-01

    A boiling-water nuclear reactor is described wherein control is effected by varying the moderator-to-fuel ratio in the reactor core. This is accomplished by providing control tubes containing a liquid control moderator in the reactor core and providing means for varying the amount of control moderatcr within the control tubes.

  20. CONVECTION REACTOR

    DOEpatents

    Hammond, R.P.; King, L.D.P.

    1960-03-22

    An homogeneous nuclear power reactor utilizing convection circulation of the liquid fuel is proposed. The reactor has an internal heat exchanger looated in the same pressure vessel as the critical assembly, thereby eliminating necessity for handling the hot liquid fuel outside the reactor pressure vessel during normal operation. The liquid fuel used in this reactor eliminates the necessity for extensive radiolytic gas rocombination apparatus, and the reactor is resiliently pressurized and, without any movable mechanical apparatus, automatically regulates itself to the condition of criticality during moderate variations in temperature snd pressure and shuts itself down as the pressure exceeds a predetermined safe operating value.

  1. Research reactors

    SciTech Connect

    Tonneson, L.C.; Fox, G.J.

    1996-04-01

    There are currently 284 research reactors in operation, and 12 under construction around the world. Of the operating reactors, nearly two-thirds are used exclusively for research, and the rest for a variety of purposes, including training, testing, and critical assembly. For more than 50 years, research reactor programs have contributed greatly to the scientific and educational communities. Today, six of the world`s research reactors are being shut down, three of which are in the USA. With government budget constraints and the growing proliferation concerns surrounding the use of highly enriched uranium in some of these reactors, the future of nuclear research could be impacted.

  2. Morphology of an Early Oligocene beaver Propalaeocastor irtyshensis and the status of the genus Propalaeocastor

    PubMed Central

    Li, Lüzhou; Lu, Xiaoyu

    2017-01-01

    The Early to Late Oligocene Propalaeocastor is the earliest known beaver genus from Eurasia. Although many species of this genus have been described, these species are defined based on very fragmentary specimens. Propalaeocastor irtyshensis from the Early Oligocene Irtysh River Formation in northwestern Xinjiang, China is one of the earliest-known members of Propalaeocastor. This species is defined on a single maxillary fragment. We revise the diagnosis of P. irtyshensis and the genus Propalaeocastor, based on newly discovered specimens from the Irtysh River Formation. The dental morphology of P. irtyshensis is very similar to other early castorids. The caudal palatine foramen of P. irtyshensis is situated in the maxillary-palatine suture. This is a feature generally accept as diagnostic character for the castorids. On the other hand, P. irtyshensis has two upper premolars, a rudimentarily developed sciuromorph-like zygomatic plate, and a relatively large protrogomorph-like infraorbital foramen. Some previous researchers suggested that Propalaeocastor is a junior synonym of Steneofiber, while other took it as a valid genus. Our morphological comparison and phylogenetic analysis suggest that Propalaeocastor differs from Steneofiber and is a valid genus. We also suggest that Agnotocastor aubekerovi, A. coloradensis, A. galushai, A. readingi, Oligotheriomys primus, and “Steneofiber aff. dehmi” should be referred to Propalaeocastor. Propalaeocastor is the earliest and most basal beaver. The origin place of Propalaeocastor and castorids is uncertain. The Early Oligocene radiation of castorids probably is propelled by the global climate change during the Eocene-Oligocene transition. PMID:28533963

  3. A case of maloccluded incisor teeth in a beaver: castor canadensis.

    PubMed

    Kim, Joong-hyun; Lee, Jae Yeong; Han, Tae-Sung; Han, Kyu-bo; Kang, Seong Soo; Bae, Chun Sik; Choi, Seok Hwa

    2005-06-01

    A three-year-old female beaver (Castor canadensis) was referred to the Veterinary Teaching Hospital of Chungbuk National University. It had been raised in the Cheong-ju zoo and had a history of malocclusion caused by improper feeding. General anesthesia was induced, and preoperative intraoral dental radiographs of the rostal maxillary and mandibular dentition were taken and lateral and ventrodorsal extraoral radiographs of the cheek teeth were also taken. The radiographs were negative for apical pathology and revealed a normal appearance of the cheek teeth. The lesion was likely to be related to the excessive length of the maxillary and mandibular incisors. Odontoplasty was performed to reduce overgrowth of the crowns of the incisors. Sequential transverse sections were removed until the crown was reduced by approximately its original length. The pulp chamber was not approached during the operation, as confirmed by postoperative intraoral radiographic evaluation of the incisors. Recovery from anesthesia was uneventful and the beaver returned to normal masticatory activities immediately after the operation.

  4. Neutral compounds from male castoreum of North American beaver,Castor canadensis.

    PubMed

    Tang, R; Webster, F X; Müller-Schwarze, D

    1995-11-01

    North American beavers (Castor canadensis) mark their territories with castoreum, the strong-smelling paste in their castor sacs. In their own territories, beavers respond with scent marking to experimental scent marks that consist of strange castoreum (or selected components). In part, the unique odor of castoreum is due to large amounts of phenolic compounds and neutral compounds. Purified neutral compounds were analyzed by GC. GC-MS, and NMR; identities of the neutral compounds were confirmed by comparing the properties of authentic compounds with those of the isolated compounds. We identified 13 neutral compounds that had not been reported before for castoreum. Most of these are oxygen-containing monoterpenes. Of the nine neutral compounds reported by Lederer (1949), only three are confirmed in our analysis; the other six neutral compounds are either absent or are not volatile enough to be detected by our methods. Eight compounds-6-methyl-l-heptanol, 4,6-dimethyl-l-heptanol, isopinocamphone, pinocamphone, two linalool oxides, and their acetates-were synthesized for structure identification and bioassays.

  5. Structure and function of a benthic invertebrate stream community as influenced by beaver (Castor canadensis).

    PubMed

    McDowell, Donald M; Naiman, Robert J

    1986-03-01

    Beaver (Castor canadensis) affect the benthic invertebrate community of small woodland streams in Quebec through habitat modifications. Their activities influence community structure through the replacement of lotic taxa by lentic forms and community function by increasing the absolute importance of collectors and predators while decreasing the relative importance of shredders and scrapers in impounded sites. At our study site during the 1983 ice-free season, standing stocks of coarse particulate organic matter (>1 mm) were 2-5 times greater (P<0.05) in impounded sites than riffle sites in spring and summer. Fine (212 μm-1 mm) and very fine (0.5 μm-212 μm) particulate organic matter were 3-10 times greater (P<0.05) in impounded sites in all seasons. Chlorophyll a standing stocks did not differ statistically among sites. Total density and biomass of invertebrates in impoundments were 2-5 times greater (P<0.05) than riffle sites in spring and summer, but statistically similar in autumn. Generic diversity (H') was greater (P<0.05) in unaltered sites in autumn. Non-impounded sites were dominated by Simuliidae, Tanytarsini chironomids, scraping mayflies and net spinning caddisflies while impounded sites were characterized by Tanypodinae and Chironomini chironomids, predacious odonates, Tubificidae, and filtering pelycopods. Our results suggest that current paradigms applied to lotic ecosystems need to be reevaluated to incorporate the influence of beaver upon invertebrate communities.

  6. Nuclear and mitochondrial genetic structure in the Eurasian beaver (Castor fiber) – implications for future reintroductions

    PubMed Central

    Senn, Helen; Ogden, Rob; Frosch, Christiane; Syrůčková, Alena; Campbell-Palmer, Roisin; Munclinger, Pavel; Durka, Walter; Kraus, Robert H S; Saveljev, Alexander P; Nowak, Carsten; Stubbe, Annegret; Stubbe, Michael; Michaux, Johan; Lavrov, Vladimir; Samiya, Ravchig; Ulevicius, Alius; Rosell, Frank

    2014-01-01

    Many reintroduction projects for conservation fail, and there are a large number of factors that may contribute to failure. Genetic analysis can be used to help stack the odds of a reintroduction in favour of success, by conducting assessment of source populations to evaluate the possibility of inbreeding and outbreeding depression and by conducting postrelease monitoring. In this study, we use a panel of 306 SNP (single nucleotide polymorphism) markers and 487–489 base pairs of mitochondrial DNA control region sequence data to examine 321 individuals from possible source populations of the Eurasian beaver for a reintroduction to Scotland. We use this information to reassess the phylogenetic history of the Eurasian beavers, to examine the genetic legacy of past reintroductions on the Eurasian landmass and to assess the future power of the genetic markers to conduct ongoing monitoring via parentage analysis and individual identification. We demonstrate the capacity of medium density genetic data (hundreds of SNPs) to provide information suitable for applied conservation and discuss the difficulty of balancing the need for high genetic diversity against phylogenetic best fit when choosing source population(s) for reintroduction. PMID:25067948

  7. Nuclear and mitochondrial genetic structure in the Eurasian beaver (Castor fiber) - implications for future reintroductions.

    PubMed

    Senn, Helen; Ogden, Rob; Frosch, Christiane; Syrůčková, Alena; Campbell-Palmer, Roisin; Munclinger, Pavel; Durka, Walter; Kraus, Robert H S; Saveljev, Alexander P; Nowak, Carsten; Stubbe, Annegret; Stubbe, Michael; Michaux, Johan; Lavrov, Vladimir; Samiya, Ravchig; Ulevicius, Alius; Rosell, Frank

    2014-06-01

    Many reintroduction projects for conservation fail, and there are a large number of factors that may contribute to failure. Genetic analysis can be used to help stack the odds of a reintroduction in favour of success, by conducting assessment of source populations to evaluate the possibility of inbreeding and outbreeding depression and by conducting postrelease monitoring. In this study, we use a panel of 306 SNP (single nucleotide polymorphism) markers and 487-489 base pairs of mitochondrial DNA control region sequence data to examine 321 individuals from possible source populations of the Eurasian beaver for a reintroduction to Scotland. We use this information to reassess the phylogenetic history of the Eurasian beavers, to examine the genetic legacy of past reintroductions on the Eurasian landmass and to assess the future power of the genetic markers to conduct ongoing monitoring via parentage analysis and individual identification. We demonstrate the capacity of medium density genetic data (hundreds of SNPs) to provide information suitable for applied conservation and discuss the difficulty of balancing the need for high genetic diversity against phylogenetic best fit when choosing source population(s) for reintroduction.

  8. Deglacial and lake level fluctuation history recorded in cores, Beaver Lake, Upper Peninsula, Michigan

    USGS Publications Warehouse

    Fisher, Timothy G.; Whitman, Richard L.

    1999-01-01

    Sediment cores collected from the littoral and pelagic zones of Beaver Lake, Michigan record fluctuations in the water level of Lake Superior. Beaver Lake is a small 300 ha lake in Pictured Rocks National Lakeshore (PRNL) now separated from Lake Superior by a dune-capped barrier bar. Cores were collected using a vibracorer from a lake-ice platform in February 1997. A 2.85 m long core in 10 m of water contains well-sorted sand, rhythmites, peat, interbedded sand and gyttja, and is capped with 1 m of massive gyttja. A 9480 BP AMS age from the basal sand provides a minimum deglacial date for the area. Further analysis indicates a sand-dominated depositional environment from a low lake stand at approximately 8500 BP to present. An approximate 8800 BP red to gray sediment color transition records either the cessation of meltwater input from Lake Agassiz or receding ice, while a younger similarly colored transition, 6600 BP in age, likely records sediment reworking in the coastal zone. Four AMS ages on peat range from 8520 to 7340 BP and are indicative of the Houghton low phase. Burial of the peat by stratified sand and gyttja after 7340 BP indicates a rising lake level. Peat at a higher level in the lake basin, encountered in shallow littoral cores, ranges in age from 6800 to 6420 BP, which estimates a 0.91 m rise/century in lake level to the Nipissing level by 5000 BP.

  9. Morphology of an Early Oligocene beaver Propalaeocastor irtyshensis and the status of the genus Propalaeocastor.

    PubMed

    Li, Lüzhou; Li, Qiang; Lu, Xiaoyu; Ni, Xijun

    2017-01-01

    The Early to Late Oligocene Propalaeocastor is the earliest known beaver genus from Eurasia. Although many species of this genus have been described, these species are defined based on very fragmentary specimens. Propalaeocastor irtyshensis from the Early Oligocene Irtysh River Formation in northwestern Xinjiang, China is one of the earliest-known members of Propalaeocastor. This species is defined on a single maxillary fragment. We revise the diagnosis of P. irtyshensis and the genus Propalaeocastor, based on newly discovered specimens from the Irtysh River Formation. The dental morphology of P. irtyshensis is very similar to other early castorids. The caudal palatine foramen of P. irtyshensis is situated in the maxillary-palatine suture. This is a feature generally accept as diagnostic character for the castorids. On the other hand, P. irtyshensis has two upper premolars, a rudimentarily developed sciuromorph-like zygomatic plate, and a relatively large protrogomorph-like infraorbital foramen. Some previous researchers suggested that Propalaeocastor is a junior synonym of Steneofiber, while other took it as a valid genus. Our morphological comparison and phylogenetic analysis suggest that Propalaeocastor differs from Steneofiber and is a valid genus. We also suggest that Agnotocastor aubekerovi, A. coloradensis, A. galushai, A. readingi, Oligotheriomys primus, and "Steneofiber aff. dehmi" should be referred to Propalaeocastor. Propalaeocastor is the earliest and most basal beaver. The origin place of Propalaeocastor and castorids is uncertain. The Early Oligocene radiation of castorids probably is propelled by the global climate change during the Eocene-Oligocene transition.

  10. Small geographic range but not panmictic: how forests structure the endangered Point Arena mountain beaver (Aplodontia rufa nigra)

    Treesearch

    William J. Zielinski; Fredrick V. Schlexer; Sean A. Parks; Kristine L. Pilgrim; Michael K. Schwartz

    2012-01-01

    The landscape genetics framework is typically applied to broad regions that occupy only small portions of a species' range. Rarely is the entire range of a taxon the subject of study. We examined the landscape genetic structure of the endangered Point Arena mountain beaver (Aplodontia rufa nigra), whose isolated geographic range is found in a...

  11. 78 FR 13384 - In the Matter of FirstEnergy Nuclear Operating Co. (Beaver Valley Units 1 and 2); Confirmatory...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-27

    ... Matter of FirstEnergy Nuclear Operating Co. (Beaver Valley Units 1 and 2); Confirmatory Order Modifying License I FirstEnergy Nuclear Operating Company (FENOC, the licensee) is the holder of Renewed Facility... From the Federal Register Online via the Government Publishing Office NUCLEAR REGULATORY...

  12. Reconnaissance investigation of high-calcium marble in the Beaver Creek area, St. Lawrence County, New York

    USGS Publications Warehouse

    Brown, C. Ervin

    1978-01-01

    Three belts of marble of the Grenville Series were mapped in the Beaver Creek drainage basin, St. Lawrence County, N.Y. One of these, on the west side of Beaver Creek, consists of coarsely crystalline pure calcitic marble that occurs in a zone at least 10 by 0.8 km in extent. Samples of marble show CaCO3 content to be greater than 93 percent, and some samples contain greater than 96 percent, and only small amounts of MgO and Fe203 are present. Marble in two other belts to the east of Beaver Creek are variable in composition, but locally have high content of calcium carbonate material. The marble deposit west of Beaver Creek has a chemical composition favorable for specialized chemical, industrial, and metallurgical uses. Another favorable aspect of the deposit is its proximity to inexpensive water transportation on the St. Lawrence Seaway only 27.5 km away by road, at Ogdensburg, N.Y.

  13. Optimal central-place foraging by beavers: Tree-size selection in relation to defensive chemicals of quaking aspen.

    PubMed

    Basey, John M; Jenkins, Stephen H; Busher, Peter E

    1988-07-01

    At a newly occupied pond, beavers preferentially felled aspen smaller than 7.5 cm in diameter and selected against larger size classes. After one year of cutting, 10% of the aspen had been cut and 14% of the living aspen exhibited the juvenile growth form. A phenolic compound which may act as a deterrent to beavers was found in low concentrations in aspen bark, and there was no significant regression of relative concentration of this compound on tree diameter. At a pond which had been intermittently occupied by beavers for over 20 years, beavers selected against aspen smaller than 4.5 cm in diameter, and selected in favor of aspen larger than 19.5 cm in diameter. After more than 28 years of cutting at this site, 51% of the aspen had been cut and 49% of the living aspen were juvenileform. The phenolic compound was found in significantly higher concentrations in aspen bark than at the newly occupied site, and there was a significant negative regression of relative concentration on tree diameter. The results of this study show that responses to browsing by trees place constraints on the predictive value of standard energy-based optimal foraging models, and limitations on the use of such models. Future models should attempt to account for inducible responses of plants to damage and increases in concentrations of secondary metabolites through time.

  14. Leave It to Beaver. Merchants Millpond State Park: An Environmental Education Learning Experience Designed for Grades 4-6.

    ERIC Educational Resources Information Center

    Williams, Floyd K.

    This learning packet, one in a group of eight, was developed by the Merchants Millpond State Park in North Carolina to teach students in grades 4-6 about the habitat and lifestyle of the beaver. Loose-leaf pages are presented in nine sections that contain: (1) introductions to the North Carolina State Parks System, the Merchants Millpond State…

  15. A range-wide occupancy estimate and habitat model for the endangered Point Arena mountain beaver (Aplodontia rufa nigra)

    Treesearch

    William J. Zielinski; Fredrick V. Schlexer; Jeffrey R. Dunk; Matthew J. Lau; James J. Graham

    2015-01-01

    The mountain beaver (Aplodontia rufa) is notably the most primitive North American rodent with a restricted distribution in the Pacific Northwest based on its physiological limits to heat stress and water needs. The Point Arena subspecies (A. r. nigra) is federally listed as endangered and is 1 of 2 subspecies that have extremely...

  16. The Relationship between Market and Accounting Determined Risk Measures: Reviewing and Updating the Beaver, Kettler, Scholes (1970) Study

    ERIC Educational Resources Information Center

    Jarvela, Michael; Kozyra, James; Potter, Carla

    2009-01-01

    The association between market-determined risk measures and accounting-determined risk measures was originally explored in the 1970s by Beaver, Kettler, and Scholes (BKS). The results of the BKS (1970) study suggest that accounting information is usefulness in assessing firm specific risk. Since BKS, there have been few studies conducted to…

  17. Major histocompatibility complex monomorphism and low levels of DNA fingerprinting variability in a reintroduced and rapidly expanding population of beavers.

    PubMed Central

    Ellegren, H; Hartman, G; Johansson, M; Andersson, L

    1993-01-01

    Loss of genetic variation due to population bottlenecks may be a severe threat for the survival of endangered species. Assessment and maintenance of genetic variability are thus crucial for conservation programs related to endangered populations. Scandinavian beavers went through an extensive bottleneck during the last century due to overhunting. In Sweden the species became extirpated but in Norway extinction was avoided by legal protection. Following reintroductions of small numbers of remaining Norwegian animals in 1922-1939, the Swedish population has increased tremendously, now harboring 100,000 animals. We show here that this viable population of beavers possesses extremely low levels of genetic variability at DNA fingerprinting loci and monomorphism at major histocompatibility complex (MHC) class I and class II loci. A similar pattern was also evident among Norwegian beavers but low levels of genetic variability were not a characteristic of the species since Russian conspecifics displayed substantial DNA fingerprinting polymorphism. However, the Russian animals were monomorphic at MHC loci, indicating that the European beaver is exceptional in its low level of MHC variability. The results demonstrate that a conservation program can be successful despite low levels of genetic variation in the founder population. Images Fig. 2 PMID:8367476

  18. 75 FR 25876 - Notice of Intent To Prepare Resource Management Plans for the Beaver Dam Wash and Red Cliffs...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-10

    ... and NEPA. 2. The BLM will use current scientific information, research, technologies, and results of... that will enhance or restore impaired systems. 3. The Joshua Tree Instant Study Area within the Beaver... and Scenic River proposals will not be evaluated or analyzed in this plan amendment process....

  19. The Relationship between Market and Accounting Determined Risk Measures: Reviewing and Updating the Beaver, Kettler, Scholes (1970) Study

    ERIC Educational Resources Information Center

    Jarvela, Michael; Kozyra, James; Potter, Carla

    2009-01-01

    The association between market-determined risk measures and accounting-determined risk measures was originally explored in the 1970s by Beaver, Kettler, and Scholes (BKS). The results of the BKS (1970) study suggest that accounting information is usefulness in assessing firm specific risk. Since BKS, there have been few studies conducted to…

  20. An 11 000-year-long record of fire and vegetation history at Beaver Lake, Oregon, central Willamette Valley

    Treesearch

    Megan K. Walsh; Christopher A. Pearl; Cathy Whitlock; Patrick J. Bartlein; Marc A. Worona

    2010-01-01

    High-resolution macroscopic charcoal and pollen analysis were used to reconstruct an 11 000-year-long record of fire and vegetation history from Beaver Lake, Oregon, the first complete Holocene paleoecological record from the floor of the Willamette Valley. In the early Holocene (ca 11 000-7500 calendar years before present [cal yr BP]), warmer, drier summers than at...

  1. Holocene planform change in broad valleys in the Southern Rocky Mountains: the role of vegetation type and beaver in shaping long-term channel complexity

    NASA Astrophysics Data System (ADS)

    Polvi-Pilgrim, L. E.; Wohl, E.

    2012-04-01

    Over the past decade, researchers have shown the importance of streambank vegetation in forming meandering channels. Recent work has also showed the importance of beaver in creating a more heterogeneous landscape, in terms of channel planform and complexity, sedimentation, and riparian vegetation. Streambank vegetation and beavers interact as ecosystem engineers to determine long-term channel planform, floodplain processes, and complexity. We use studies of Holocene beaver aggradation and effects on channel complexity, in addition to measurements of added bank strength by various riparian vegetation types, to predict Holocene planform change in broad (>200 m, disconnected from hillslopes), high-elevation (>2300 m) valleys of the Colorado Front Range in the Southern Rocky Mountains. Sediment core analyses and shallow subsurface geophysical measurements indicate that post-glacial beaver-related aggradation is significant. Additionally, historical and field evidence from the last century, when the beaver population steadily declined, shows that beaver contribute to the formation of a complex, multi-thread channel network. Streambank vegetation in the Colorado Front Range can be categorized based on its ability to provide added strength to the streambank, where riparian or rhizomatous shrubs and trees provide more strength than xeric trees or non-rhizomatous graminoids and herbs, depending on the bank texture and hydrologic conditions. Assuming a snowmelt-dominated flow regime in a gravel-bed channel system, four planform regimes are identified based on beaver populations and the abundance and presence of xeric or riparian vegetation. Following deglaciation, without beaver or bank-stabilizing vegetation, (1) a braided channel formed. The introduction of riparian vegetation and a more stable flow regime triggered a transition to (2) a meandering channel, which in turn provided habitat for beaver, allowing the formation of (3) a complex multi-thread channel system. The

  2. Morphological and neuroanatomical study of the mammary gland in the immature and mature European beaver (Castor fiber).

    PubMed

    Franke-Radowiecka, Amelia; Giżejewski, Zygmunt; Klimczuk, Magdalena; Dudek, Agnieszka; Zalecki, Michal; Jurczak, Andrzej; Kaleczyc, Jerzy

    2016-10-01

    This study investigated general morphology and immunohistochemical properties of nerve fibres supplying the mammary gland (MG) in the European beaver. The microscopic analysis of the beaver mammary gland revealed the presence of morphological structures which are characteristic for mammals. There were no distinct differences in the morphological features of the mammary gland between the juvenile and non-pregnant mature beaver. The nerve fibres were visualized using antibodies against protein gene product 9.5 (PGP) and biologically active substances including β-hydroxylase tyrosine (DβH), neuropeptide Y (NPY), calcitonine gene-related peptide (CGRP) and substance P (SP). The study has revealed that the MG in the juvenile and mature beaver is richly supplied with PGP-immunoreactive (PGP-IR) nerve fibres. The most abundant innervation was observed in the nipple and less numerous nerve terminals supplied the glandular tissue. Double-labelling immunohistochemistry disclosed that the majority of PGP-IR nerve fibres associated with blood vessels and smooth muscle cells in both the nipple and glandular tissue were also DßH-IR. However, these nerve terminals were less numerous in the glandular tissue than in the nipple. Most of the DßH-IR axons associated with arteries and smooth muscle cells in the entire gland also stained for NPY. Small number of DßH/NPY-IR fibres supplied veins. CGRP-IR fibres were more abundant than those expressing SP. No distinct differences in the distribution and immunohistochemical characteristic of nerve fibres were observed between the juvenile and adult animals. The distribution and immunohistochemical properties of nerve fibres supplying the gland in the beaver remind those previously described in other mammalian species.

  3. NEUTRONIC REACTOR

    DOEpatents

    Fraas, A.P.; Mills, C.B.

    1961-11-21

    A neutronic reactor in which neutron moderation is achieved primarily in its reflector is described. The reactor structure consists of a cylindrical central "island" of moderator and a spherical moderating reflector spaced therefrom, thereby providing an annular space. An essentially unmoderated liquid fuel is continuously passed through the annular space and undergoes fission while contained therein. The reactor, because of its small size, is particularly adapted for propulsion uses, including the propulsion of aircraft. (AEC)

  4. REACTOR COOLING

    DOEpatents

    Quackenbush, C.F.

    1959-09-29

    A nuclear reactor with provisions for selectively cooling the fuel elements is described. The reactor has a plurality of tubes extending throughout. Cylindrical fuel elements are disposed within the tubes and the coolant flows through the tubes and around the fuel elements. The fuel elements within the central portion of the reactor are provided with roughened surfaces of material. The fuel elements in the end portions of the tubes within the reactor are provlded with low conduction jackets and the fuel elements in the region between the central portion and the end portions are provided with smooth surfaces of high heat conduction material.

  5. Central place foraging by beavers (Castor canadensis): a test of foraging predictions and the impact of selective feeding on the growth form of cottonwoods (Populus fremontii).

    PubMed

    McGinley, Mark A; Whitham, Thomas G

    1985-07-01

    Several predictions of central place foraging theory were tested. As predicted, beavers foraged more selectively at increasing distance from the central place. With increasing distance from the river's edge, beavers cut fewer branches and deleted small branches from their diet. Large branches were favored at all distances, which differs from patterns observed in previous studies of beaver foraging. This difference, however, is expected and supports Schoener's (1979) predictions which are based on differences between provisioning costs and item size.The selective harvesting of branches predicted by foraging theory affects plant growth form and may influence plant reproductive patterns. High rates of branch removal caused cottonwoods to develop a shrubby architecture. The importance of selective branch choice by beavers on patterns of cottonwood reproduction (i.e., delayed sexual maturity and induced cloning) is discussed.

  6. Hyporheic Exchange in a Stream Dammed by Beaver: A 1D Simulation with Spatial Energy Head Gradients and Heterogeneous Hydraulic Conductivity as Drivers

    NASA Astrophysics Data System (ADS)

    Fairfax, E. J.; Small, E. E.

    2016-12-01

    Hyporheic exchange, the exchange of water between streams and adjacent subsurface sediments, is an important process connecting groundwater and surface water. Knowing the location and magnitude of hyporheic exchange is useful in evaluating fish spawning habitats, biogeochemical processes, and capacity for aquifer recharge of a given stream. Hyporheic exchange through the streambed is driven by variations in longitudinal head gradient and spatial heterogeneity in hydraulic conductivity. Beaver damming directly effects these two drivers. Beaver dams are efficient flow obstructions that cause significant upstream ponding. Both the flow obstruction itself (the beaver dam) and the pool of deeper water (the beaver pond) increase streambed pressure. Increased streambed pressure alters the energy head gradients within the stream and drives enhanced hyporheic exchange. Additionally, several studies in the literature have found increased sedimentation rates within beaver ponds, particularly of finer particles and organic material that otherwise might not settle out of a faster-moving, undammed stream. This means sediment aggradation along the longitudinal profile of a stream-dam-pond system varies in both volume and type. Nonuniform volume of aggraded sediment further changes streambed topography, and in turn energy head gradients. Nonuniform sediment type results in heterogeneous hydraulic conductivity - the other driver of enhanced hyporheic exchange. We use a 1D model of hyporheic exchange based on Laplace's Equation and Darcy's Equation for a system at steady-state. We utilize observed and theoretical streambed profiles in streams dammed by beaver to explore how the hyporheic exchange in a stream might change through time after a beaver dam is built. The model produces a series of steady-state snapshots of the stream-dam-pond system through time. The simulations demonstrate that on relatively short timescales (months-years) beaver damming can lead to more pronounced

  7. Mitochondrial Genomes Reveal Slow Rates of Molecular Evolution and the Timing of Speciation in Beavers (Castor), One of the Largest Rodent Species

    PubMed Central

    Horn, Susanne; Durka, Walter; Wolf, Ronny; Ermala, Aslak; Stubbe, Annegret; Stubbe, Michael; Hofreiter, Michael

    2011-01-01

    Background Beavers are one of the largest and ecologically most distinct rodent species. Little is known about their evolution and even their closest phylogenetic relatives have not yet been identified with certainty. Similarly, little is known about the timing of divergence events within the genus Castor. Methodology/Principal Findings We sequenced complete mitochondrial genomes from both extant beaver species and used these sequences to place beavers in the phylogenetic tree of rodents and date their divergence from other rodents as well as the divergence events within the genus Castor. Our analyses support the phylogenetic position of beavers as a sister lineage to the scaly tailed squirrel Anomalurus within the mouse related clade. Molecular dating places the divergence time of the lineages leading to beavers and Anomalurus as early as around 54 million years ago (mya). The living beaver species, Castor canadensis from North America and Castor fiber from Eurasia, although similar in appearance, appear to have diverged from a common ancestor more than seven mya. This result is consistent with the hypothesis that a migration of Castor from Eurasia to North America as early as 7.5 mya could have initiated their speciation. We date the common ancestor of the extant Eurasian beaver relict populations to around 210,000 years ago, much earlier than previously thought. Finally, the substitution rate of Castor mitochondrial DNA is considerably lower than that of other rodents. We found evidence that this is correlated with the longer life span of beavers compared to other rodents. Conclusions/Significance A phylogenetic analysis of mitochondrial genome sequences suggests a sister-group relationship between Castor and Anomalurus, and allows molecular dating of species divergence in congruence with paleontological data. The implementation of a relaxed molecular clock enabled us to estimate mitochondrial substitution rates and to evaluate the effect of life history traits

  8. Mitochondrial genomes reveal slow rates of molecular evolution and the timing of speciation in beavers (Castor), one of the largest rodent species.

    PubMed

    Horn, Susanne; Durka, Walter; Wolf, Ronny; Ermala, Aslak; Stubbe, Annegret; Stubbe, Michael; Hofreiter, Michael

    2011-01-28

    Beavers are one of the largest and ecologically most distinct rodent species. Little is known about their evolution and even their closest phylogenetic relatives have not yet been identified with certainty. Similarly, little is known about the timing of divergence events within the genus Castor. We sequenced complete mitochondrial genomes from both extant beaver species and used these sequences to place beavers in the phylogenetic tree of rodents and date their divergence from other rodents as well as the divergence events within the genus Castor. Our analyses support the phylogenetic position of beavers as a sister lineage to the scaly tailed squirrel Anomalurus within the mouse related clade. Molecular dating places the divergence time of the lineages leading to beavers and Anomalurus as early as around 54 million years ago (mya). The living beaver species, Castor canadensis from North America and Castor fiber from Eurasia, although similar in appearance, appear to have diverged from a common ancestor more than seven mya. This result is consistent with the hypothesis that a migration of Castor from Eurasia to North America as early as 7.5 mya could have initiated their speciation. We date the common ancestor of the extant Eurasian beaver relict populations to around 210,000 years ago, much earlier than previously thought. Finally, the substitution rate of Castor mitochondrial DNA is considerably lower than that of other rodents. We found evidence that this is correlated with the longer life span of beavers compared to other rodents. A phylogenetic analysis of mitochondrial genome sequences suggests a sister-group relationship between Castor and Anomalurus, and allows molecular dating of species divergence in congruence with paleontological data. The implementation of a relaxed molecular clock enabled us to estimate mitochondrial substitution rates and to evaluate the effect of life history traits on it.

  9. Cadmium in beavers translocated from the Elbe River to the Rhine/Meuse estuary, and the possible effect on population growth rate.

    PubMed

    Nolet, B A; Dijkstra, V A; Heidecke, D

    1994-08-01

    Beavers (Castor fiber) from the Middle Elbe region were re-introduced in the Biesbosch, The Netherlands, and estuary contaminated with cadmium (Cd) by the rivers Rhine and Meuse. The Middle Elbe region was also polluted with Cd, but the beavers released in the Biesbosch originated from two relatively clean habitats within this region. The Biesbosch population grew slower than other released beaver populations in Europe, and it was hypothesized that Cd intoxication was responsible for this. The beavers fed primarily on the bark and leaves of willow and poplar trees, which contained great concentrations of Cd. The average Cd concentration in the food (6.9 micrograms/g(dry)) was above the maximum tolerable concentration for large domestic herbivores. The Cd concentrations of the kidneys and hair of the beavers were correlated with those in the bark of the trees. The Cd concentration in the hair increased threefold after the release in the Biesbosch, and the geometric mean Cd kidney concentration was 55 micrograms/g(dry). Using three different models, an average Cd kidney concentration in the beavers of > 100 micrograms/g(dry) was predicted in the Biesbosch in the near future. Such a concentration causes kidney damage in some other mammals. Beaver kidneys fro the Mulde, a tributary of the Elbe, contained on average 467 micrograms Cd/g(dry), the greatest concentration reported in herbivores. Nevertheless, the fertility along the Mulde was high, due to the fact that it is an otherwise optimal beaver habitat. Furthermore, the low fertility in the Biesbosch was due to a small fraction of successful breeding pairs. We conclude that the initial low population growth rate in the Biesbosch was probably not caused by contamination with Cd. However, future effects on the individual (reproductive) life span cannot be ruled out.

  10. Municipal waterborne giardiasis: an epidemilogic investigation. Beavers implicated as a possible reservoir.

    PubMed

    Dykes, A C; Juranek, D D; Lorenz, R A; Sinclair, S; Jakubowski, W; Davies, R

    1980-02-01

    In March 1976, 128 persons in Camas, Washington, had laboratory-confirmed giardiasis. A questionnaire survey of 498 Camas residents revealed that 3.8% had clinical giardiasis, while none of 318 residents in a control town were ill. No associations between illness and sex, pet ownership, travel, time spent in wilderness areas, public gatherings, or food preference were found. Giardia cysts were recovered from raw water entering the city water treatment system via two streams and also from two storage reservoirs containing chlorinated and filtered stream water. Failure to remove Giardia cysts was attributed to the water plants' inadequate flocculation, coagulation, and sedimentation combined with deterioration of the filter media. Investigation of the watershed revealed no signs of human fecal contamination. Animal trapping in the watershed area yielded three beavers (Castor canadensis) infected with Giardia that were infective for specific pathogen-free beagle pups.

  11. Prevalence of agglutinating antibodies to Toxoplasma gondii and Sarcocystis neurona in beavers (Castor canadensis) from Massachusetts

    USGS Publications Warehouse

    Jordan, C.N.; Kaur, T.; Koenen, K.; DeStefano, S.; Zajac, A.M.; Lindsay, D.S.

    2005-01-01

    The present study examined the seroprevalence of Toxoplasma gondii and Sarcocystls neurona in a population of beavers (Castor canadensis) from Massachusetts. Sixty-two blood samples were collected during the field seasons over 3 consecutive years from different animals. Blood was collected onto filter paper and shipped to the Department of Biomedical Sciences, Virginia Tech, Blacksburg, Virginia, for parasite testing. The samples were tested at dilutions of 1:25, 1:50, and 1:100 against each parasite antigen by modified agglutination tests to determine whether antibodies to either parasite were present in the blood. Six of 62 samples (10%) were positive for T. gondii, with 2 samples having titers of 1:25 and 4 having titers of 1:50. Four of 62 samples (6%) were positive for S. neurona, with 2 samples having titers of 1:25 and 2 having titers of 1:50. ?? American Society of Pathologists 2005.

  12. Prevalence of agglutinating antibodies to Toxoplasma gondii and Sarcocystis neurona in beavers (Castor canadensis) from Massachusetts.

    PubMed

    Jordan, Carly N; Kaur, Taranjit; Koenen, Kiana; DeStefano, Stephen; Zajac, Anne M; Lindsay, David S

    2005-10-01

    The present study examined the seroprevalence of Toxoplasma gondii and Sarcocystis neurona in a population of beavers (Castor canadensis) from Massachusetts. Sixty-two blood samples were collected during the field seasons over 3 consecutive years from different animals. Blood was collected onto filter paper and shipped to the Department of Biomedical Sciences, Virginia Tech, Blacksburg, Virginia, for parasite testing. The samples were tested at dilutions of 1:25, 1:50, and 1:100 against each parasite antigen by modified agglutination tests to determine whether antibodies to either parasite were present in the blood. Six of 62 samples (10%) were positive for T. gondii, with 2 samples having titers of 1:25 and 4 having titers of 1:50. Four of 62 samples (6%) were positive for S. neurona, with 2 samples having titers of 1:25 and 2 having titers of 1:50.

  13. Diagnostic x-ray exposure and lens opacities: the Beaver Dam Eye Study.

    PubMed Central

    Klein, B E; Klein, R; Linton, K L; Franke, T

    1993-01-01

    The Beaver Dam Eye Study is a population-based study of common age-related eye diseases. During the standardized medical history, the 4926 subjects were asked whether they had ever had a chest x-ray, computerized axial tomography (CAT) scan of the head, other x-rays of the head, x-rays of the abdomen, or other diagnostic x-rays. The eye examination included photographs of the lenses of the eyes, which were subsequently graded according to protocol. Nuclear sclerosis and posterior subcapsular opacity were significantly associated with CAT scans. If these relationships are causal, it would highlight the importance of minimizing such exposure to the lens of the eye. PMID:8460743

  14. Distributed Temperature Sensing of hyporheic flux patterns in varied space and time around beaver dams

    NASA Astrophysics Data System (ADS)

    Briggs, M.; Lautz, L. K.; McKenzie, J. M.

    2010-12-01

    Small dams enhance hyporheic interaction by creating punctuated head differentials along streams, thereby affecting redox conditions and nutrient cycling in the streambed. As beaver populations return, they create dams that alter hyporheic flowpaths locally, an effect which may integrate at the reach scale to produce a net hydrological and ecological functional change. Streambed heterogeneity around beaver dams combines with varied morphology, head differentials and stream velocities to create patterns of hyporheic seepage flux that vary in both space and time. Heat has been used as a groundwater tracer for many years, but it’s dependence on spatially disperse point measurements has only recently been resolved by the development of Distributed Temperature Sensing (DTS) fiber-optic technology. Modified applications of DTS include wrapping the fiber around a mandrel to increase spatial resolution dramatically. Wrapped configurations can be installed vertically in the streambed to provide data for heat transport modeling of vertical hyporheic flux. The vertically continuous dataset generated with DTS may be more informative regarding subsurface heterogeneity than more commonly used spatially discrete thermocouples. We installed a total of nine wrapped DTS rods with 1.4 cm vertical spatial resolution above two beaver dams in Cherry Creek, a tributary of the Little Popo Agie River in Lander, Wyoming, USA. Data was collected over 20 min periods in dual-ended mode continuously for one month (10-Jul to 10-Aug 2010) during baseflow recession, as discharge dropped from 384 Ls-1 to 211 Ls-1. The temperature rods were installed to at least 0.75 m depth within bed sediments at varied distances upstream of the dams in diverse stream morphological units, which ranged from gravel bars to clay lined pools. Diurnal fluctuations in stream temperature were generally between 4.5 and 5.5 oC in amplitude, imparting a strong potential signal for propagation into the bed due to advective

  15. [Introduction of species and microevolution: the European beaver, raccoon dog, and American mink].

    PubMed

    Korablev, N P; Korablev, M P; Korablev, P N

    2011-01-01

    Nine skull samples of the beaver Castor fiber, six samples of the raccoon dog Nyctereutes procyonoides, and six samples of the American mink Neovison vison were studied using phenetic and craniometric methods. Analysis of the phenofund structure suggests that in all of the studied species the emergence of novel character variations does not lead to their fixation with a significant frequency. Considerable morphological variability emerges in the contact zone of different autochtonous populations, of wild and breeding forms, as well as in geographically and reproductively isolated small groups of individuals. Morphological differences of introduced animals fit into the conception of species polymorphism and are smoothed over when separate colonies merge into metapopulations, which does not lead to the emergence of novel stable taxa.

  16. NEUTRONIC REACTOR

    DOEpatents

    Wigner, E.P.

    1958-04-22

    A nuclear reactor for isotope production is described. This reactor is designed to provide a maximum thermal neutron flux in a region adjacent to the periphery of the reactor rather than in the center of the reactor. The core of the reactor is generally centrally located with respect tn a surrounding first reflector, constructed of beryllium. The beryllium reflector is surrounded by a second reflector, constructed of graphite, which, in tune, is surrounded by a conventional thermal shield. Water is circulated through the core and the reflector and functions both as a moderator and a coolant. In order to produce a greatsr maximum thermal neutron flux adjacent to the periphery of the reactor rather than in the core, the reactor is designed so tbat the ratio of neutron scattering cross section to neutron absorption cross section averaged over all of the materials in the reflector is approximately twice the ratio of neutron scattering cross section to neutron absorption cross section averaged over all of the material of the core of the reactor.

  17. Reactor building

    SciTech Connect

    Hista, J. C.

    1984-09-18

    Reactor building comprising a vessel shaft anchored in a slab which is peripherally locked. This reactor building comprises a confinement enclosure within which are positioned internal structures constituted by an internal structure floor, a vessel shaft, a slab being positioned between the general floor and the internal structure floor, the vesse

  18. NEUTRONIC REACTOR

    DOEpatents

    Metcalf, H.E.; Johnson, H.W.

    1961-04-01

    BS>A nuclear reactor incorporating fuel rods passing through a moderator and including tubes of a material of higher Thermal conductivity than the fuel in contact with the fuel is described. The tubes extend beyond the active portion of the reactor into contant with a fiuld coolant.

  19. Hydrologic analysis of the proposed Badger-Beaver Creeks Artificial-Recharge Project : Morgan County, Colorado

    USGS Publications Warehouse

    Burns, Alan W.

    1980-01-01

    A hydrologic analysis of the proposed Badger-Beaver Creeks artificial-recharge project in Morgan County, Colo., was made with the aid of three digital computer models: A canal-distribution model, a ground-water flow model, and a stream-aquifer model. Statistical summaries of probable diversions from the South Platte River based on a 27-year period of historical flows indicate that an average-annual diversion of 96,000 acre-feet and a median-annual diversion of 43,000 acre-feet would be available. Diversions would sustain water in ponds for waterfowl habitat for an average of about five months per year, with a miximum pond surface area of about 300 acres with the median diversions and a maximum pond surface area of about 1,250 acres at least one-half of the years with the historic diversions. If the annual diversion were 43,000 acre-feet, recharge to the two alluvial aquifers would raise water levels sufficiently to create flowing streams in the channels of Beaver and Badger Creeks while allowing an increase in current ground-water pumping. The only area of significant waterlogging would be along the proposed delivery canal on the west edge of Badger Creek valley. If the total water available were diverted, the aquifer system could not transmit the water fast enough to the irrigation areas to avoid considerable waterlogging in the recharge areas. The impact of the proposed project on the South Platte River basin would be minimal once the ground-water system attained steady-state conditions, but that may take decades with a uniform diversion of the 43,000 acre-feet annually. (USGS)

  20. 226Ra and other radionuclides in water, vegetation, and tissues of beavers (Castor canadensis) from a watershed containing U tailings near Elliot Lake, Canada.

    PubMed

    Clulow, F V; Mirka, M A; Davé, N K; Lim, T P

    1991-01-01

    Radionuclide levels were measured in tissues, gut contents, diet items, and water at site of capture, of adult beavers from the Serpent River drainage basin which contains U tailings at Elliot Lake, Ontario, and from nearby control sites. Levels of (226)Ra in beaver bone, muscle and kidney were highest in animals from locations close to U tailings; liver levels did not vary by site. Environmental (226)Ra levels were within ranges previously reported at these or similar locations elsewhere; levels in beaver gut contents reflected levels in diet items. Concentration ratios exceeded unity only between some vegetation items and beaver bone at the Elliot Lake site and were less than 0.19 between vegetation and other tissues. In two beavers with tissue levels of (226)Ra higher than other sampled, neither (232)Th nor (230)Th were detected in bone, muscle or liver tissues. U-238 was measurable in bone, muscle and liver, (228)Th in bone, (210)Po bone, muscle and liver; and (210)Pb was measurable only in bone. Estimated yearly intakes of radionuclides by people eating beavers were calculated to be below current allowable levels set by the Canadian regulatory authorities.

  1. Fire effects on the Point Reyes Mountain Beaver (Aplodontia rufa phaea) at Point Reyes National Seashore, 10 years after the Vision Fire

    USGS Publications Warehouse

    Fellers, Gary M.; Osbourn, Michael

    2009-01-01

    The 1995 Vision Fire burned 5000 ha and destroyed 40% of the habitat of the Point Reyes Mountain Beaver (Aplodontia rufa phaea). Surveys immediately post-fire and in 2000 showed that only 0.4 to 1.7% of Mountain Beavers within the burn area survived. In 2000, dense, ground-hugging Blue-blossom Ceanothus (Ceanothus thrysiflorus) appeared to make coastal scrub thickets much less suitable for Mountain Beavers even though the number of burrows at our 11 study sites had returned to 88% of pre-fire numbers. In 2005 (10 y post-fire), the habitat appeared to be better for Mountain Beavers; Blue-blossom Ceanothus had diminished and vegetation more typical of northern coastal scrub, such as Coyote Brush (Baccharis pilularis) overstory with a lower layer of herbaceous vegetation, had greatly increased; but the number of Mountain Beaver burrows had declined to 52% of pre-fire numbers and there was little change in the number of sites occupied between our 2000 and 2005 surveys. With the expected successional changes in thicket structure, Mountain Beaver populations are likely to recover further, but there will probably be considerable variation in how each population stabilizes.

  2. Ambient conditions and fate and transport simulations of dissolved solids, chloride, and sulfate in Beaver Lake, Arkansas, 2006--10

    USGS Publications Warehouse

    Green, W. Reed

    2013-01-01

    Beaver Lake is a large, deep-storage reservoir located in the upper White River Basin in northwestern Arkansas, and was completed in 1963 for the purposes of flood control, hydroelectric power, and water supply. Beaver Lake is affected by point and nonpoint sources of minerals, nutrients, and sediments. The City of Fayetteville discharges about half of its sewage effluent into the White River immediately upstream from the backwater of the reservoir. The City of West Fork discharges its sewage effluent into the West Fork of the White River, and the City of Huntsville discharges its sewage effluent into a tributary of War Eagle Creek. A study was conducted to describe the ambient conditions and fate and transport of dissolved solids, chloride, and sulfate concentrations in Beaver Lake. Dissolved solids, chloride, and sulfate are components of wastewater discharged into Beaver Lake and a major concern of the drinking water utilities that use Beaver Lake as their source. A two-dimensional model of hydrodynamics and water quality was calibrated to include simulations of dissolved solids, chloride, and sulfate for the period January 2006 through December 2010. Estimated daily dissolved solids, chloride, and sulfate loads were increased in the White River and War Eagle Creek tributaries, individually and the two tributaries together, by 1.2, 1.5, 2.0, 5.0, and 10.0 times the baseline conditions to examine fate and transport of these constituents through time at seven locations (segments) in the reservoir, from upstream to downstream in Beaver Lake. Fifteen dissolved solids, chloride, and sulfate fate and transport scenarios were compared to the baseline simulation at each of the seven downstream locations in the reservoir, both 2 meters (m) below the surface and 2 m above the bottom. Concentrations were greater in the reservoir at model segments closer to where the tributaries entered the reservoir. Concentrations resulting from the increase in loading became more diluted

  3. Characterizing the morphological complexity of North American beaver (Castor canadensis) habitats using ground-based LiDAR

    NASA Astrophysics Data System (ADS)

    Welsh, S. B.; Wheaton, J. M.; Bouwes, N. W.; Pollock, M. M.; Demeurichy, K. G.

    2009-12-01

    Beavers (Castor canadensis) are frequently referred to as ‘ecosystem engineers’ in part because of the profound influence their dams and associated networks of dens, side-channels and pools have on habitat heterogeneity and the complexity of the environments they occupy. Recently, beaver have been incorporated into stream restoration efforts to help reconnect incised streams to their floodplains and improve physical habitat for fish and other species of concern. Although these ecosystem engineers produce rich and complex habitats, they do not provide as-built drawings of their work and the dynamic habitats they construct are very difficult to survey and characterize for monitoring their effectiveness. Traditional ground-based topographic, vegetation and habitat surveys are often inadequate to properly characterize such habitats or detect change. Similarly, traditional remotely sensed data may lack the resolution and accuracy to detect important changes through time. To better understand the character and dynamics of these complex habitats created by beaver, we will present some data and new techniques for describing their structure using a hybrid ground-based and remote-sensing technology: ground-based LiDaR (a.k.a. terrestrial laser scanning - TLS). Specifically, we are seeking to use this data to explore the feedbacks between key components - beaver, riparian vegetation, channel complexity and their collective influence on salmonid habitat. The combination of high resolution and high accuracy 3D point clouds from TLS data provides new opportunities for characterizing physical habitat and detecting changes with repeat surveys. However, TLS also presents significant methodological challenges in how we manage and analyze data, which may be 2 to 5 orders of magnitude greater in size then traditional ground-based or remotely sensed data sets. Preliminary data and analyses from algorithms under on-going development will be presented. The data is from the first year

  4. Compact Reactor

    NASA Astrophysics Data System (ADS)

    Williams, Pharis E.

    2007-01-01

    Weyl's Gauge Principle of 1929 has been used to establish Weyl's Quantum Principle (WQP) that requires that the Weyl scale factor should be unity. It has been shown that the WQP requires the following: quantum mechanics must be used to determine system states; the electrostatic potential must be non-singular and quantified; interactions between particles with different electric charges (i.e. electron and proton) do not obey Newton's Third Law at sub-nuclear separations, and nuclear particles may be much different than expected using the standard model. The above WQP requirements lead to a potential fusion reactor wherein deuterium nuclei are preferentially fused into helium nuclei. Because the deuterium nuclei are preferentially fused into helium nuclei at temperatures and energies lower than specified by the standard model there is no harmful radiation as a byproduct of this fusion process. Therefore, a reactor using this reaction does not need any shielding to contain such radiation. The energy released from each reaction and the absence of shielding makes the deuterium-plus-deuterium-to-helium (DDH) reactor very compact when compared to other reactors, both fission and fusion types. Moreover, the potential energy output per reactor weight and the absence of harmful radiation makes the DDH reactor an ideal candidate for space power. The logic is summarized by which the WQP requires the above conditions that make the prediction of DDH possible. The details of the DDH reaction will be presented along with the specifics of why the DDH reactor may be made to cause two deuterium nuclei to preferentially fuse to a helium nucleus. The presentation will also indicate the calculations needed to predict the reactor temperature as a function of fuel loading, reactor size, and desired output and will include the progress achieved to date.

  5. Compact Reactor

    SciTech Connect

    Williams, Pharis E.

    2007-01-30

    Weyl's Gauge Principle of 1929 has been used to establish Weyl's Quantum Principle (WQP) that requires that the Weyl scale factor should be unity. It has been shown that the WQP requires the following: quantum mechanics must be used to determine system states; the electrostatic potential must be non-singular and quantified; interactions between particles with different electric charges (i.e. electron and proton) do not obey Newton's Third Law at sub-nuclear separations, and nuclear particles may be much different than expected using the standard model. The above WQP requirements lead to a potential fusion reactor wherein deuterium nuclei are preferentially fused into helium nuclei. Because the deuterium nuclei are preferentially fused into helium nuclei at temperatures and energies lower than specified by the standard model there is no harmful radiation as a byproduct of this fusion process. Therefore, a reactor using this reaction does not need any shielding to contain such radiation. The energy released from each reaction and the absence of shielding makes the deuterium-plus-deuterium-to-helium (DDH) reactor very compact when compared to other reactors, both fission and fusion types. Moreover, the potential energy output per reactor weight and the absence of harmful radiation makes the DDH reactor an ideal candidate for space power. The logic is summarized by which the WQP requires the above conditions that make the prediction of DDH possible. The details of the DDH reaction will be presented along with the specifics of why the DDH reactor may be made to cause two deuterium nuclei to preferentially fuse to a helium nucleus. The presentation will also indicate the calculations needed to predict the reactor temperature as a function of fuel loading, reactor size, and desired output and will include the progress achieved to date.

  6. NUCLEAR REACTOR

    DOEpatents

    Moore, R.V.; Bowen, J.H.; Dent, K.H.

    1958-12-01

    A heterogeneous, natural uranium fueled, solid moderated, gas cooled reactor is described, in which the fuel elements are in the form of elongated rods and are dlsposed within vertical coolant channels ln the moderator symmetrically arranged as a regular lattice in groups. This reactor employs control rods which operate in vertical channels in the moderator so that each control rod is centered in one of the fuel element groups. The reactor is enclosed in a pressure vessel which ls provided with access holes at the top to facilitate loading and unloadlng of the fuel elements, control rods and control rod driving devices.

  7. Trends in base flows and extreme flows in the Beaver Kill Basin, Catskill Mountains, New York, 1915-94

    USGS Publications Warehouse

    Baldigo, Barry P.

    1999-01-01

    The increases in peak stormflows in the lower Beaver Kill basin through the period of record may have increased the rates of bed-sediment erosion (degradation) and deposition and accelerated changes in stream-channel morphology, however, these possible effects were not examined. Suggestions for further investigation of the effects of NY 17 and of other factors on hydrology, channel morphology, fish habitat, and fish populations in the Beaver Kill Basin include (1) addition of streamflow gages or a creststage gage network at critical locations, (2) a review of engineering records and other aerial photographs for indications of changes in channel morphology, (3) compilation of temperature data and modeling spatial extent and magnitude of stressful summer temperatures (to selected trout species), and (4) confirming the extent and severity of toxic thermal episodes using in-situ fish toxicity tests.

  8. Stream flow, salmon and beaver dams: roles in the structuring of stream fish communities within an anadromous salmon dominated stream.

    PubMed

    Mitchell, Sean C; Cunjak, Richard A

    2007-11-01

    The current paradigm of fish community distribution is one of a downstream increase in species richness by addition, but this concept is based on a small number of streams from the mid-west and southern United States, which are dominated by cyprinids. Further, the measure of species richness traditionally used, without including evenness, may not be providing an accurate reflection of the fish community. We hypothesize that in streams dominated by anadromous salmonids, fish community diversity will be affected by the presence of the anadromous species, and therefore be influenced by those factors affecting the salmonid population. Catamaran Brook, New Brunswick, Canada, provides a long-term data set to evaluate fish community diversity upstream and downstream of an obstruction (North American beaver Castor canadensis dam complex), which affects distribution of Atlantic salmon Salmo salar. The Shannon Weiner diversity index and community evenness were calculated for sample sites distributed throughout the brook and over 15 years. Fish community diversity was greatest upstream of the beaver dams and in the absence of Atlantic salmon. The salmon appear to depress the evenness of the community but do not affect species richness. The community upstream of the beaver dams changes due to replacement of slimy sculpin Cottus cognatus by salmon, rather than addition, when access is provided. Within Catamaran Brook, location of beaver dams and autumn streamflow interact to govern adult Atlantic salmon spawner distribution, which then dictates juvenile production and effects on fish community. These communities in an anadromous Atlantic salmon dominated stream do not follow the species richness gradient pattern shown in cyprinid-dominated streams and an alternative model for stream fish community distribution in streams dominated by anadromous salmonids is presented. This alternative model suggests that community distribution may be a function of semipermeable obstructions

  9. Geochemistry of stream-sediment samples from the Santa Renia Fields and Beaver Peak quadrangles, northern Carlin Trend, Nevada

    USGS Publications Warehouse

    Theodore, Ted G.; Kotlyar, Boris B.; Berger, Vladimir I.; Moring, Barry C.; Singer, Donald A.; Edstrom, Sven A.

    1999-01-01

    A broad west-to-east increase of many metal concentrations has been found in stream sediments during a reconnaissance investigation conducted in conjunction with geologic studies in the Santa Renia Fields and Beaver Peak 7–1/2 minute quadrangles near the northern end of the Carlin trend of gold deposits in the Tuscarora Mountains. This regional increase in metal concentrations coincides with a dramatic change in landform wherein high concentrations of metals in stream sediments appear to correlate directly with areas of high elevations and steep slopes in the Beaver Peak quadrangle. Robust erosion combined with high flow rates in streams from these higher elevations are envisaged to have contributed significantly to increased metal concentrations in the stream sediments by an enhanced presence of minerals with high specific gravities and a correspondingly diminished presence of minerals with low specific gravities. Minerals with low specific gravities probably have been preferentially flushed down stream because of high transporting capacities for sediment by streams in the Beaver Peak quadrangle. In addition, the Carlin trend, a generally northwest-alignment of gold deposits in the Santa Renia Fields quadrangle, is well outlined by arsenic concentrations that include a maximum of approximately 54 parts per million. Further, a weakly developed distal-to-proximal metal zonation towards these gold deposits appears to be defined respectively in plots showing distributions of thallium, arsenic, antimony, and zinc. A broad area of high metal concentrations—including sharply elevated abundances of Ag, As, Au, Cd, Co, Cu, Mn, Ni, P, Sb, Sc, Te, V, and especially Zn—near the southeast corner of the Beaver Peak quadrangle primarily could be the result of stratiform mineralized rocks in the Ordovician Vinini Formation or Devonian Slaven Chert, or the result of a subsequent Mesozoic or Tertiary epigenetic overprint.

  10. NEUTRONIC REACTOR

    DOEpatents

    Fermi, E.

    1960-04-01

    A nuclear reactor is described consisting of blocks of graphite arranged in layers, natural uranium bodies disposed in holes in alternate layers of graphite blocks, and coolant tubes disposed in the layers of graphite blocks which do not contain uranium.

  11. NEUTRONIC REACTORS

    DOEpatents

    Wigner, E.P.

    1960-11-22

    A nuclear reactor is described wherein horizontal rods of thermal- neutron-fissionable material are disposed in a body of heavy water and extend through and are supported by spaced parallel walls of graphite.

  12. NEUTRONIC REACTOR

    DOEpatents

    Anderson, H.L.

    1960-09-20

    A nuclear reactor is described comprising fissionable material dispersed in graphite blocks, helium filling the voids of the blocks and the spaces therebetween, and means other than the helium in thermal conductive contact with the graphite for removing heat.

  13. Reactor apparatus

    DOEpatents

    Echtler, J. Paul

    1981-01-01

    A reactor apparatus for hydrocracking a polynuclear aromatic hydrocarbonaceous feedstock to produce lighter hydrocarbon fuels by contacting the hydrocarbonaceous feedstock with hydrogen in the presence of a molten metal halide catalyst.

  14. Chemical Reactors.

    ERIC Educational Resources Information Center

    Kenney, C. N.

    1980-01-01

    Describes a course, including content, reading list, and presentation on chemical reactors at Cambridge University, England. A brief comparison of chemical engineering education between the United States and England is also given. (JN)

  15. NEUTRONIC REACTOR

    DOEpatents

    Hurwitz, H. Jr.; Brooks, H.; Mannal, C.; Payne, J.H.; Luebke, E.A.

    1959-03-24

    A reactor of the heterogeneous, liquid cooled type is described. This reactor is comprised of a central region of a plurality of vertically disposed elongated tubes surrounded by a region of moderator material. The central region is comprised of a central core surrounded by a reflector region which is surrounded by a fast neutron absorber region, which in turn is surrounded by a slow neutron absorber region. Liquid sodium is used as the primary coolant and circulates through the core which contains the fuel elements. Control of the reactor is accomplished by varying the ability of the reflector region to reflect neutrons back into the core of the reactor. For this purpose the reflector is comprised of moderator and control elements having varying effects on reactivity, the control elements being arranged and actuated by groups to give regulation, shim, and safety control.

  16. Reactor Engineering

    NASA Astrophysics Data System (ADS)

    Lema, Juan M.; López, Carmen; Eibes, Gemma; Taboada-Puig, Roberto; Moreira, M. Teresa; Feijoo, Gumersindo

    In this chapter, the engineering aspects of processes catalyzed by peroxidases will be presented. In particular, a discussion of the existing technologies that utilize peroxidases for different purposes, such as the removal of recalcitrant compounds or the synthesis of polymers, is analyzed. In the first section, the essential variables controlling the process will be investigated, not only those that are common in any enzymatic system but also those specific to peroxidative reactions. Next, different reactor configurations and operational modes will be proposed, emphasizing their suitability and unsuitability for different systems. Finally, two specific reactors will be described in detail: enzymatic membrane reactors and biphasic reactors. These configurations are especially valuable for the treatment of xenobiotics with high and poor water solubility, respectively.

  17. NUCLEAR REACTOR

    DOEpatents

    Miller, H.I.; Smith, R.C.

    1958-01-21

    This patent relates to nuclear reactors of the type which use a liquid fuel, such as a solution of uranyl sulfate in ordinary water which acts as the moderator. The reactor is comprised of a spherical vessel having a diameter of about 12 inches substantially surrounded by a reflector of beryllium oxide. Conventionnl control rods and safety rods are operated in slots in the reflector outside the vessel to control the operation of the reactor. An additional means for increasing the safety factor of the reactor by raising the ratio of delayed neutrons to prompt neutrons, is provided and consists of a soluble sulfate salt of beryllium dissolved in the liquid fuel in the proper proportion to obtain the result desired.

  18. NUCLEAR REACTOR

    DOEpatents

    Sherman, J.; Sharbaugh, J.E.; Fauth, W.L. Jr.; Palladino, N.J.; DeHuff, P.G.

    1962-10-23

    A nuclear reactor incorporating seed and blanket assemblies is designed. Means are provided for obtaining samples of the coolant from the blanket assemblies and for varying the flow of coolant through the blanket assemblies. (AEC)

  19. REACTOR SHIELD

    DOEpatents

    Wigner, E.P.; Ohlinger, L.E.; Young, G.J.; Weinberg, A.M.

    1959-02-17

    Radiation shield construction is described for a nuclear reactor. The shield is comprised of a plurality of steel plates arranged in parallel spaced relationship within a peripheral shell. Reactor coolant inlet tubes extend at right angles through the plates and baffles are arranged between the plates at right angles thereto and extend between the tubes to create a series of zigzag channels between the plates for the circulation of coolant fluid through the shield. The shield may be divided into two main sections; an inner section adjacent the reactor container and an outer section spaced therefrom. Coolant through the first section may be circulated at a faster rate than coolant circulated through the outer section since the area closest to the reactor container is at a higher temperature and is more radioactive. The two sections may have separate cooling systems to prevent the coolant in the outer section from mixing with the more contaminated coolant in the inner section.

  20. Castor sacs and anal glands of the north american beaver (Castor canadensis): their histology, development, and relationship to scent communication.

    PubMed

    Walro, J M; Svendsen, G E

    1982-05-01

    Both sexes of beavers possess a pair of castor sacs and a pair of anal glands located in paired subcutaneous cavities between the pelvis and the base of the tail. The castor sacs are not glandular in the histological sense, hence references to these structures as preputial glands or castor glands are misnomers. The wall of the castor sacs is plicate and comprised of three distinct zones: an outer layer of vascular connective tissue, a two-to five-cell-thick layer of mitotic epithelial cells, and several densely packed layers of cornified epithelium which grade into more widely separated sheets toward the lumen. Monocultures of a gram-positive facultatively anaerobic bacterium were present in the lumen of all castor sac preparations. Differences in the frequency of castoreum deposition were not attributable to differences in the structure of the castor sacs. The anal glands of beavers are holocrine sebaceous glands. These glands develop more rapidly than the castor sacs. Anal gland tissue from embryos exhibited cellular characteristics associated with the production of sebum. Secretory activity was evident in all preparations. The relationship of castoreum and anal gland secretion to scent communication among beavers is discussed.

  1. High rates of energy expenditure and water flux in free-ranging Point Reyes mountain beavers Aplodontia rufa phaea

    USGS Publications Warehouse

    Crocker, D.E.; Kofahl, N.; Fellers, G.D.; Gates, N.B.; Houser, D.S.

    2007-01-01

    We measured water flux and energy expenditure in free-ranging Point Reyes mountain beavers Aplodontia rufa phaea by using the doubly labeled water method. Previous laboratory investigations have suggested weak urinary concentrating ability, high rates of water flux, and low basal metabolic rates in this species. However, free-ranging measurements from hygric mammals are rare, and it is not known how these features interact in the environment. Rates of water flux (210 ?? 32 mL d-1) and field metabolic rates (1,488 ?? 486 kJ d-1) were 159% and 265%, respectively, of values predicted by allometric equations for similar-sized herbivores. Mountain beavers can likely meet their water needs through metabolic water production and preformed water in food and thus remain in water balance without access to free water. Arginine-vasopressin levels were strongly correlated with rates of water flux and plasma urea : creatinine ratios, suggesting an important role for this hormone in regulating urinary water loss in mountain beavers. High field metabolic rates may result from cool burrow temperatures that are well below lower critical temperatures measured in previous laboratory studies and suggest that thermoregulation costs may strongly influence field energetics and water flux in semifossorial mammals. ?? 2007 by The University of Chicago. All rights reserved.

  2. High rates of energy expenditure and water flux in free-ranging Point Reyes mountain beavers Aplodontia rufa phaea.

    PubMed

    Crocker, Daniel E; Kofahl, Nathan; Fellers, Gary D; Gates, Natalie B; Houser, Dorian S

    2007-01-01

    We measured water flux and energy expenditure in free-ranging Point Reyes mountain beavers Aplodontia rufa phaea by using the doubly labeled water method. Previous laboratory investigations have suggested weak urinary concentrating ability, high rates of water flux, and low basal metabolic rates in this species. However, free-ranging measurements from hygric mammals are rare, and it is not known how these features interact in the environment. Rates of water flux (210+/-32 mL d(-1)) and field metabolic rates (1,488+/-486 kJ d(-1)) were 159% and 265%, respectively, of values predicted by allometric equations for similar-sized herbivores. Mountain beavers can likely meet their water needs through metabolic water production and preformed water in food and thus remain in water balance without access to free water. Arginine-vasopressin levels were strongly correlated with rates of water flux and plasma urea : creatinine ratios, suggesting an important role for this hormone in regulating urinary water loss in mountain beavers. High field metabolic rates may result from cool burrow temperatures that are well below lower critical temperatures measured in previous laboratory studies and suggest that thermoregulation costs may strongly influence field energetics and water flux in semifossorial mammals.

  3. Hydrologic Change during the Colonial Era of the United States: Beavers and the Energy Cost of Impoundments (Invited)

    NASA Astrophysics Data System (ADS)

    Green, M. B.; Bain, D. J.; Arrigo, J. S.; Duncan, J. M.; Kumar, S.; Parolari, A.; Salant, N.; Vorosmarty, C. J.; Aloysius, N. R.; Bray, E. N.; Ruffing, C. M.; Witherell, B. B.

    2009-12-01

    Europeans colonized North America in the early 17th century with intentions ranging between long-term inhabitation and quick extraction of resources for economic gain in Europe. Whatever the intentions, the colonists relied on the landscape for resources resulting in dramatic change to the forest and fur-bearing mammal population. We demonstrate that initial exploitation of North American forest and furs caused a substantial decrease in mean water residence time (τ) between 1600 and 1800 A.D. That loss, which regionally changed from 51 to 41 days, contrasts with conventional wisdom that humans tend to diminish variability in water resources by increasing storage capacity and thus increasing τ. The loss of τ resulted from over-hunted beaver for the hat market in Europe. Analysis suggests that colonial era demographics and economics did not allow human resource allocation to impoundment construction on a level matching the historic beaver effort. However, the τ appears to have regionally increased during the 19th century, suggesting that humans eventually began replacing the water storage lost with the beaver. The analysis highlights the energy cost of impounding water, which is likely to continue to be an important factor given the increasing need for stable water resources and finite energy resources.

  4. NEUTRONIC REACTORS

    DOEpatents

    Vernon, H.C.

    1959-01-13

    A neutronic reactor of the heterogeneous, fluid cooled tvpe is described. The reactor is comprised of a pressure vessel containing the moderator and a plurality of vertically disposed channels extending in spaced relationship through the moderator. Fissionable fuel material is placed within the channels in spaced relationship thereto to permit circulation of the coolant fluid. Separate means are provided for cooling the moderator and for circulating a fluid coolant thru the channel elements to cool the fuel material.

  5. NUCLEAR REACTOR

    DOEpatents

    Anderson, C.R.

    1962-07-24

    A fluidized bed nuclear reactor and a method of operating such a reactor are described. In the design means are provided for flowing a liquid moderator upwardly through the center of a bed of pellets of a nentron-fissionable material at such a rate as to obtain particulate fluidization while constraining the lower pontion of the bed into a conical shape. A smooth circulation of particles rising in the center and falling at the outside of the bed is thereby established. (AEC)

  6. NUCLEAR REACTOR

    DOEpatents

    Breden, C.R.; Dietrich, J.R.

    1961-06-20

    A water-soluble non-volatile poison may be introduced into a reactor to nullify excess reactivity. The poison is removed by passing a side stream of the water containing the soluble poison to an evaporation chamber. The vapor phase is returned to the reactor to decrease the concentration of soluble poison and the liquid phase is returned to increase the concentration of soluble poison.

  7. NUCLEAR REACTOR

    DOEpatents

    Grebe, J.J.

    1959-07-14

    High temperature reactors which are uniquely adapted to serve as the heat source for nuclear pcwered rockets are described. The reactor is comprised essentially of an outer tubular heat resistant casing which provides the main coolant passageway to and away from the reactor core within the casing and in which the working fluid is preferably hydrogen or helium gas which is permitted to vaporize from a liquid storage tank. The reactor core has a generally spherical shape formed entirely of an active material comprised of fissile material and a moderator material which serves as a diluent. The active material is fabricated as a gas permeable porous material and is interlaced in a random manner with very small inter-connecting bores or capillary tubes through which the coolant gas may flow. The entire reactor is divided into successive sections along the direction of the temperature gradient or coolant flow, each section utilizing materials of construction which are most advantageous from a nuclear standpoint and which at the same time can withstand the operating temperature of that particular zone. This design results in a nuclear reactor characterized simultaneously by a minimum critiral size and mass and by the ability to heat a working fluid to an extremely high temperature.

  8. Research reactors - an overview

    SciTech Connect

    West, C.D.

    1997-03-01

    A broad overview of different types of research and type reactors is provided in this paper. Reactor designs and operating conditions are briefly described for four reactors. The reactor types described include swimming pool reactors, the High Flux Isotope Reactor, the Mark I TRIGA reactor, and the Advanced Neutron Source reactor. Emphasis in the descriptions is placed on safety-related features of the reactors. 7 refs., 7 figs., 2 tabs.

  9. Echinococcus multilocularis Detection in Live Eurasian Beavers (Castor fiber) Using a Combination of Laparoscopy and Abdominal Ultrasound under Field Conditions.

    PubMed

    Campbell-Palmer, Róisín; Del Pozo, Jorge; Gottstein, Bruno; Girling, Simon; Cracknell, John; Schwab, Gerhard; Rosell, Frank; Pizzi, Romain

    2015-01-01

    Echinococcus multilocularis is an important pathogenic zoonotic parasite of health concern, though absent in the United Kingdom. Eurasian beavers (Castor fiber) may act as a rare intermediate host, and so unscreened wild caught individuals may pose a potential risk of introducing this parasite to disease-free countries through translocation programs. There is currently no single definitive ante-mortem diagnostic test in intermediate hosts. An effective non-lethal diagnostic, feasible under field condition would be helpful to minimise parasite establishment risk, where indiscriminate culling is to be avoided. This study screened live beavers (captive, n = 18 or wild-trapped in Scotland, n = 12) and beaver cadavers (wild Scotland, n = 4 or Bavaria, n = 11), for the presence of E. multilocularis. Ultrasonography in combination with minimally invasive surgical examination of the abdomen by laparoscopy was viable under field conditions for real-time evaluation in beavers. Laparoscopy alone does not allow the operator to visualize the parenchyma of organs such as the liver, or inside the lumen of the gastrointestinal tract, hence the advantage of its combination with abdominal ultrasonography. All live beavers and Scottish cadavers were largely unremarkable in their haematology and serum biochemistry with no values suspicious for liver pathology or potentially indicative of E. multilocularis infection. This correlated well with ultrasound, laparoscopy, and immunoblotting, which were unremarkable in these individuals. Two wild Bavarian individuals were suspected E. multilocularis positive at post-mortem, through the presence of hepatic cysts. Sensitivity and specificity of a combination of laparoscopy and abdominal ultrasonography in the detection of parasitic liver cyst lesions was 100% in the subset of cadavers (95%Confidence Intervals 34.24-100%, and 86.7-100% respectively). For abdominal ultrasonography alone sensitivity was only 50% (95%CI 9.5-90.6%), with

  10. Hydrogeology, water quality, and ground-water development alternatives in the Beaver-Pasquiset ground-water reservoir, Rhode Island

    USGS Publications Warehouse

    Dickerman, D.C.; Ozbilgin, M.M.

    1985-01-01

    In a 23 sq mi study area, the Beaver-Pasquiset groundwater reservoir within the Pawcatuck River basin in southern Rhode Island, stratified drift is the only principal geologic unit capable of producing yields > 350 gal/min. Transmissivity of the aquifer ranges from 7,200 to 24,300 sq ft/day. Water table conditions prevail in the aquifer, which is in good hydraulic connection with perennial streams and ponds. A digital model of two-dimensional groundwater flow was used to simulate the interaction between surface water and groundwater, and to evaluate the impact of alternative schemes of groundwater development on groundwater levels, pond levels, and streamflow in the Beaver-Pasquiset groundwater reservoir. Transient simulations of theoretical pumpage were made for a drought period (1963-66) and a wet period (1976-78). The areas most favorable for development of high-capacity wells (350 gal/min or more) are along the Beaver River and near Pasquiset Pond. The water is soft and generally contains < 100 mg/L dissolved solids. Locally, groundwater contains elevated concentrations of iron and manganese (7.5 and 3.7 mg/L, respectively), southeast of Pasquiset Pond, and will require treatment if used for public supply. The groundwater reservoir was simulated with a two-dimensional finite-difference model using a block-centered grid consisting of 33 rows and 75 columns. Differences between measured and simulated water table altitudes for the final steady state run for 21 selected observation wells averaged +0.07 ft. Combined pumping rates for simulation of groundwater development alternatives at eight sites ranged from 3.25 to 7.00 Mgal/d. Pumping rates for individual wells ranged from 0.25 to 1.50 Mgal/d. Transient simulations suggest that the Beaver-Pasquiset groundwater reservoir is capable of sustaining a pumping rate of 4.25 Mgal/d during years of average groundwater recharge with minimal impact on groundwater levels, pond levels, and streamflow. During extreme drought

  11. Echinococcus multilocularis Detection in Live Eurasian Beavers (Castor fiber) Using a Combination of Laparoscopy and Abdominal Ultrasound under Field Conditions

    PubMed Central

    Gottstein, Bruno; Cracknell, John; Schwab, Gerhard; Rosell, Frank

    2015-01-01

    Echinococcus multilocularis is an important pathogenic zoonotic parasite of health concern, though absent in the United Kingdom. Eurasian beavers (Castor fiber) may act as a rare intermediate host, and so unscreened wild caught individuals may pose a potential risk of introducing this parasite to disease-free countries through translocation programs. There is currently no single definitive ante-mortem diagnostic test in intermediate hosts. An effective non-lethal diagnostic, feasible under field condition would be helpful to minimise parasite establishment risk, where indiscriminate culling is to be avoided. This study screened live beavers (captive, n = 18 or wild-trapped in Scotland, n = 12) and beaver cadavers (wild Scotland, n = 4 or Bavaria, n = 11), for the presence of E. multilocularis. Ultrasonography in combination with minimally invasive surgical examination of the abdomen by laparoscopy was viable under field conditions for real-time evaluation in beavers. Laparoscopy alone does not allow the operator to visualize the parenchyma of organs such as the liver, or inside the lumen of the gastrointestinal tract, hence the advantage of its combination with abdominal ultrasonography. All live beavers and Scottish cadavers were largely unremarkable in their haematology and serum biochemistry with no values suspicious for liver pathology or potentially indicative of E. multilocularis infection. This correlated well with ultrasound, laparoscopy, and immunoblotting, which were unremarkable in these individuals. Two wild Bavarian individuals were suspected E. multilocularis positive at post-mortem, through the presence of hepatic cysts. Sensitivity and specificity of a combination of laparoscopy and abdominal ultrasonography in the detection of parasitic liver cyst lesions was 100% in the subset of cadavers (95%Confidence Intervals 34.24–100%, and 86.7–100% respectively). For abdominal ultrasonography alone sensitivity was only 50% (95%CI 9.5–90.6%), with

  12. Instream investigations in the Beaver Creek Watershed in West Tennessee, 1991-95

    USGS Publications Warehouse

    Byl, T.D.; Carney, K.A.

    1996-01-01

    The U.S. Geological Survey (USGS), in cooperation with the Tennessee Department of Agriculture, began a long-term scientific investigation in 1989 to evaluate the effect of agricultural activities on water quality and the effectiveness of agricultural best management practices in the Beaver Creek watershed, West Tennessee. In 1993 as a part of this study, the USGS, in cooperation with the Natural Resources Conservation Service, Shelby County Soil Conservation District, and the Tennessee Soybean Promotion Board, began an evaluation of the physical, chemical, biological and hydrological factors that affect water quality in streams and wetlands, and instream resource-management systems to treat agricultural nonpoint-source runoff and improve water quality. The purpose of this report is to present the results of three studies of stream and wetland investigations and a study on the transport of aldicarb from an agricultural field in the Beaver Creek watershed. A natural bottomland hardwood wetland and an artificially constructed wetland were evaluated as instream resource-management systems. These two studies showed that wetlands are an effective way to improve the quality of agricultural nonpoint-source runoff. The wetlands reduced concentrations and loads of suspended sediments, nutrients, and pesticides in the streams. A third paper documents the influence of riparian vegetation on the biological structure and water quality of a small stream draining an agricultural field. A comparison of the upper reach lined with herbaceous plants and the lower reach with mature woody vegetation showed a more stable biological community structure and Water- quality characteristics in the woody reach than in the herbaceous reach. The water-quality characteristics monitored were pH, temperature, dissolved oxygen, and specific conductance. The herbaceous reach had a greater diversity and abundance of organisms during spring and early summer, but the abundance dropped by approximately

  13. The coal deposits of the Alkali Butte, the Big Sand Draw, and the Beaver Creek fields, Fremont County, Wyoming

    USGS Publications Warehouse

    Thompson, Raymond M.; White, Vincent L.

    1952-01-01

    Large coal reserves are present in three areas located between 12 and 20 miles southeast of Riverton, Fremont County, central Wyoming. Coal in two of these areas, the Alkali Butte coal field and the Big Sand Draw coal field, is exposed on the surface and has been developed to some extent by underground mining. The Beaver Creek coal field is known only from drill cuttings and cores from wells drilled for oil and gas in the Beaver Creek oil and gas field.These three coal areas can be reached most readily from Riverton, Wyo. State Route 320 crosses Wind River about 1 mile south of Riverton. A few hundred yards south of the river a graveled road branches off the highway and extends south across the Popo Agie River toward Sand Draw oil and gas field. About 8 miles south of the highway along the Sand Draw road, a dirt road bears east and along this road it is about 12 miles to the Bell coal mine in the Alkali Butte coal field. Three miles southeast of the Alkali Butte turn-off, 3 miles of oiled road extends southwest into the Beaver Creek oil and gas field. About 6 miles southeast of the Beaver Creek turn-off, in the valley of Little Sand Draw Creek, a dirt road extends east 1. mile and then southeast 1 mile to the Downey mine in the Big Sand Draw coal field. Location of these coal fields is shown on figure 1 with their relationship to the Wind River basin and other coal fields, place localities, and wells mentioned in this report. The coal in the Alkali Butte coal field is exposed partly on the Wind River Indian Reservation in Tps. 1 and 2 S., R. 6 E., and partly on public land. Coal in the Beaver Creek and Big Sand Draw coal fields is mainly on public land. The region has a semiarid climate with rainfall averaging less than 10 in. per year. When rain does fall the sandy-bottomed stream channels fill rapidly and are frequently impassable for a few hours. Beaver Creek, Big Sand Draw, Little Sand Draw, and Kirby Draw and their smaller tributaries drain the area and flow

  14. NEUTRONIC REACTOR

    DOEpatents

    Ohlinger, L.A.; Wigner, E.P.; Weinberg, A.M.; Young, G.J.

    1958-09-01

    This patent relates to neutronic reactors of the heterogeneous water cooled type, and in particular to a fuel element charging and discharging means therefor. In the embodiment illustrated the reactor contains horizontal, parallel coolant tubes in which the fuel elements are disposed. A loading cart containing a magnzine for holding a plurality of fuel elements operates along the face of the reactor at the inlet ends of the coolant tubes. The loading cart is equipped with a ram device for feeding fuel elements from the magazine through the inlot ends of the coolant tubes. Operating along the face adjacent the discharge ends of the tubes there is provided another cart means adapted to receive irradiated fuel elements as they are forced out of the discharge ends of the coolant tubes by the incoming new fuel elements. This cart is equipped with a tank coataining a coolant, such as water, into which the fuel elements fall, and a hydraulically operated plunger to hold the end of the fuel element being discharged. This inveation provides an apparatus whereby the fuel elements may be loaded into the reactor, irradiated therein, and unloaded from the reactor without stopping the fiow of the coolant and without danger to the operating personnel.

  15. The impacts of Phalaris arundinacea (reed canary grass) invasion on wetland plant richness in the Oregon Coast Range, USA, depend on beavers

    USGS Publications Warehouse

    Perkins, T.; Wilson, M.

    2005-01-01

    Invasive plants can threaten diversity and ecosystem function. We examined the relationship between the invasive Phalaris arundinacea (reed canarygrass) and species richness in beaver wetlands in Oregon, USA. Four basins (drainages) were chosen and three sites each of beaver impoundments, unimpounded areas and areas upstream of debris jams were randomly chosen in each basin for further study (n = 36). Analysis of covariance (ANCOVA) showed that the relationship between Phalaris and species richness differed significantly (p = 0.01) by site type. Dam sites (beaver impoundments) exhibited a strong inverse relationship between Phalaris and species richness (bD = a??0.15), with one species lost for each 7% increase in Phalaris cover. In contrast, there was essentially no relationship between Phalaris cover and species richness in jam sites (debris jam impoundments formed by flooding; bJ = +0.01) and unimpounded sites (bU = a??0.03). The cycle of beaver impoundment and abandonment both disrupts the native community and provides an ideal environment for Phalaris, which once established tends to exclude development of herbaceous communities and limits species richness. Because beaver wetlands are a dominant wetland type in the Coast Range, Phalaris invasion presents a real threat to landscape heterogeneity and ecosystem function in the region.

  16. NUCLEAR REACTOR

    DOEpatents

    Christy, R.F.

    1958-07-15

    A nuclear reactor of the homogeneous liquid fuel type is described wherein the fissionable isotope is suspended or dissolved in a liquid moderator such as water. The reactor core is comprised essentially of a spherical vessel for containing the reactive composition surrounded by a reflector, preferably of beryllium oxide. The reactive composition may be an ordinary water solution of a soluble salt of uranium, the quantity of fissionable isotope in solution being sufficient to provide a critical mass in the vessel. The liquid fuel is stored in a tank of non-crtttcal geometry below the reactor vessel and outside of the reflector and is passed from the tank to the vessel through a pipe connecting the two by air pressure means. Neutron absorbing control and safety rods are operated within slots in the reflector adjacent to the vessel.

  17. NEUTRONIC REACTOR

    DOEpatents

    Metcalf, H.E.

    1957-10-01

    A reactor of the type which preferably uses plutonium as the fuel and a liquid moderator, preferably ordinary water, and which produces steam within the reactor core due to the heat of the chain reaction is described. In the reactor shown the fuel elements are essentially in the form of trays and are ventically stacked in spaced relationship. The water moderator is continuously supplied to the trays to maintain a constant level on the upper surfaces of the fuel element as it is continually evaporated by the heat. The steam passes out through the spaces between the fuel elements and is drawn off at the top of the core. The fuel elements are clad in aluminum to prevent deterioration thereof with consequent contamimation of the water.

  18. REACTOR CONTROL

    DOEpatents

    Fortescue, P.; Nicoll, D.

    1962-04-24

    A control system employed with a high pressure gas cooled reactor in which a control rod is positioned for upward and downward movement into the neutron field from a position beneath the reactor is described. The control rod is positioned by a coupled piston cylinder releasably coupled to a power drive means and the pressurized coolant is directed against the lower side of the piston. The coolant pressure is offset by a higher fiuid pressure applied to the upper surface of the piston and means are provided for releasing the higher pressure on the upper side of the piston so that the pressure of the coolant drives the piston upwardly, forcing the coupled control rod into the ncutron field of the reactor. (AEC)

  19. NEUTRONIC REACTORS

    DOEpatents

    Wigner, E.P.; Young, G.J.

    1958-10-14

    A method is presented for loading and unloading rod type fuel elements of a neutronic reactor of the heterogeneous, solld moderator, liquid cooled type. In the embodiment illustrated, the fuel rods are disposed in vertical coolant channels in the reactor core. The fuel rods are loaded and unloaded through the upper openings of the channels which are immersed in the coolant liquid, such as water. Unloading is accomplished by means of a coffer dam assembly having an outer sleeve which is placed in sealing relation around the upper opening. A radiation shield sleeve is disposed in and reciprocable through the coffer dam sleeve. A fuel rod engaging member operates through the axial bore in the radiation shield sleeve to withdraw the fuel rod from its position in the reactor coolant channel into the shield, the shield snd rod then being removed. Loading is accomplished in the reverse procedure.

  20. Bioconversion reactor

    DOEpatents

    McCarty, Perry L.; Bachmann, Andre

    1992-01-01

    A bioconversion reactor for the anaerobic fermentation of organic material. The bioconversion reactor comprises a shell enclosing a predetermined volume, an inlet port through which a liquid stream containing organic materials enters the shell, and an outlet port through which the stream exits the shell. A series of vertical and spaced-apart baffles are positioned within the shell to force the stream to flow under and over them as it passes from the inlet to the outlet port. The baffles present a barrier to the microorganisms within the shell causing them to rise and fall within the reactor but to move horizontally at a very slow rate. Treatment detention times of one day or less are possible.

  1. Catalytic reactor

    SciTech Connect

    Aaron, Timothy Mark; Shah, Minish Mahendra; Jibb, Richard John

    2009-03-10

    A catalytic reactor is provided with one or more reaction zones each formed of set(s) of reaction tubes containing a catalyst to promote chemical reaction within a feed stream. The reaction tubes are of helical configuration and are arranged in a substantially coaxial relationship to form a coil-like structure. Heat exchangers and steam generators can be formed by similar tube arrangements. In such manner, the reaction zone(s) and hence, the reactor is compact and the pressure drop through components is minimized. The resultant compact form has improved heat transfer characteristics and is far easier to thermally insulate than prior art compact reactor designs. Various chemical reactions are contemplated within such coil-like structures such that as steam methane reforming followed by water-gas shift. The coil-like structures can be housed within annular chambers of a cylindrical housing that also provide flow paths for various heat exchange fluids to heat and cool components.

  2. POWER REACTOR

    DOEpatents

    Zinn, W.H.

    1958-07-01

    A fast nuclear reactor system ls described for producing power and radioactive isotopes. The reactor core is of the heterogeneous, fluid sealed type comprised of vertically arranged elongated tubular fuel elements having vertical coolant passages. The active portion is surrounded by a neutron reflector and a shield. The system includes pumps and heat exchangers for the primary and secondary coolant circuits. The core, primary coolant pump and primary heat exchanger are disposed within an irapenforate tank which is filled with the primary coolant, in this case a liquid metal such as Na or NaK, to completely submerge these elements. The tank is completely surrounded by a thick walled concrete shield. This reactor system utilizes enriched uranium or plutonium as the fissionable material, uranium or thorium as a diluent and thorium or uranium containing less than 0 7% of the U/sup 235/ isotope as a fertile material.

  3. Re-Evaluation of Sinocastor (Rodentia: Castoridae) with Implications on the Origin of Modern Beavers

    PubMed Central

    Rybczynski, Natalia; Ross, Elizabeth M.; Samuels, Joshua X.; Korth, William W.

    2010-01-01

    The extant beaver, Castor, has played an important role shaping landscapes and ecosystems in Eurasia and North America, yet the origins and early evolution of this lineage remain poorly understood. Here we use a geometric morphometric approach to help re-evaluate the phylogenetic affinities of a fossil skull from the Late Miocene of China. This specimen was originally considered Sinocastor, and later transferred to Castor. The aim of this study was to determine whether this form is an early member of Castor, or if it represents a lineage outside of Castor. The specimen was compared to 38 specimens of modern Castor (both C. canadensis and C. fiber) as well as fossil specimens of C. fiber (Pleistocene), C. californicus (Pliocene) and the early castorids Steneofiber eseri (early Miocene). The results show that the specimen falls outside the Castor morphospace and that compared to Castor, Sinocastor possesses a: 1) narrower post-orbital constriction, 2) anteroposteriorly shortened basioccipital depression, 3) shortened incisive foramen, 4) more posteriorly located palatine foramen, 5) longer rostrum, and 6) longer braincase. Also the specimen shows a much shallower basiocciptal depression than what is seen in living Castor, as well as prominently rooted molars. We conclude that Sinocastor is a valid genus. Given the prevalence of apparently primitive traits, Sinocastor might be a near relative of the lineage that gave rise to Castor, implying a possible Asiatic origin for Castor. PMID:21085579

  4. Gross anatomy of the cardiac blood vessels in the North American beaver (Castor canadensis).

    PubMed

    Bisaillon, A

    1981-01-01

    The cardiac arteries and veins are described in the North American beaver (Castor canadensis) following the injection of the vessels of 15 hearts with either latex, vinyl plastic or barium sulfate. The left coronary artery gives off the typical circumflex and paraconal interventricular branches which supply the left atrium and ventricle and part of the right ventricle and interventricular septum. The right coronary artery vascularizes the right atrium and ventricule and by means of its subsinuosal interventricular branch, part of the left ventricle and interventricular septum. The paraconal interventricular branch of the left coronary artery lies within the myocardium and is not visible on the surface of the heart. There are no intercoronary anastomoses between the right and left vessels. The major cardiac veins open into the terminal end of the left cranial vena cava. Unlike the arteries, there are venous anastomoses interconnecting the great cardiac vein and the middle cardiac vein. It is concluded that the cardiac blood vessels in Castor canadensis are typically mammalian and resemble those of both land and aquatic mammals.

  5. Management by assertion: beavers and songbirds at Lake Skinner (Riverside County, California).

    PubMed

    Longcore, Travis; Rich, Catherine; Müller-Schwarze, Dietland

    2007-04-01

    Management of ecological reserve lands should rely on the best available science to achieve the goal of biodiversity conservation. "Adaptive Resource Management" is the current template to ensure that management decisions are reasoned and that decisions increase understanding of the system being managed. In systems with little human disturbance, certain management decisions are clear; steps to protect native species usually include the removal of invasive species. In highly modified systems, however, appropriate management steps to conserve biodiversity are not as readily evident. Managers must, more than ever, rely upon the development and testing of hypotheses to make rational management decisions. We present a case study of modern reserve management wherein beavers (Castor canadensis) were suspected of destroying habitat for endangered songbirds (least Bell's vireo, Vireo bellii pusillus, and southwestern willow flycatcher, Empidonax traillii extimus) and for promoting the invasion of an exotic plant (tamarisk, Tamarix spp.) at an artificial reservoir in southern California. This case study documents the consequences of failing to follow the process of Adaptive Resource Management. Managers made decisions that were unsupported by the scientific literature, and actions taken were likely counterproductive. The opportunity to increase knowledge of the ecosystem was lost. Uninformed management decisions, essentially "management by assertion," undermine the long-term prospects for biodiversity conservation.

  6. Re-evaluation of Sinocastor (Rodentia: Castoridae) with implications on the origin of modern beavers.

    PubMed

    Rybczynski, Natalia; Ross, Elizabeth M; Samuels, Joshua X; Korth, William W

    2010-11-15

    The extant beaver, Castor, has played an important role shaping landscapes and ecosystems in Eurasia and North America, yet the origins and early evolution of this lineage remain poorly understood. Here we use a geometric morphometric approach to help re-evaluate the phylogenetic affinities of a fossil skull from the Late Miocene of China. This specimen was originally considered Sinocastor, and later transferred to Castor. The aim of this study was to determine whether this form is an early member of Castor, or if it represents a lineage outside of Castor. The specimen was compared to 38 specimens of modern Castor (both C. canadensis and C. fiber) as well as fossil specimens of C. fiber (Pleistocene), C. californicus (Pliocene) and the early castorids Steneofiber eseri (early Miocene). The results show that the specimen falls outside the Castor morphospace and that compared to Castor, Sinocastor possesses a: 1) narrower post-orbital constriction, 2) anteroposteriorly shortened basioccipital depression, 3) shortened incisive foramen, 4) more posteriorly located palatine foramen, 5) longer rostrum, and 6) longer braincase. Also the specimen shows a much shallower basiocciptal depression than what is seen in living Castor, as well as prominently rooted molars. We conclude that Sinocastor is a valid genus. Given the prevalence of apparently primitive traits, Sinocastor might be a near relative of the lineage that gave rise to Castor, implying a possible Asiatic origin for Castor.

  7. Depositional environmental and geologic age of neogene rocks at Cape Aliaksin, Beaver Bay, Alaska Peninsula

    SciTech Connect

    Armentrout, J.M.

    1985-04-01

    Neogene sandstone and conglomerate cropping out along the eastern end of Beaver Bay at Cape Aliaksin have been assigned to the Unga Conglomerate Member of the Bear Lake formation. New data suggest that this correlation may be incorrect. The fossil assemblage includes gastropods, pelecypods, barnacles, and echionoids indicative of a shallow marine, cold-water biofacies. Taxa indicate a strong similarity to the fossil assemblage of the Tachilni Formation and the upper Bear Lake Formation, both assigned to the late Miocene Graysian Molluscan stage, approximately 12 Ma to 3 Ma. Teeth of the desmostylian (sea cows) Desmostylus sp. cf. D. hesperus have been collected from the Cape Aliaksin beds. D. Hesperus is known from North Pacific rocks assigned to the late early to early late Miocene, approximately 18 ma to 10 Ma. The Unga Conglomerate is in part typified by the middle Miocene pelecypod Mytilus gratacapi and an associated fauna unlike that of the Cape Aliaksin beds. It is suggested that the Cape Aliaksin beds are younger than the Unga Conglomerate, and are correlative to the upper Bear Lake Formation and Tachilni Formation rocks of early late Miocene age.

  8. NEUTRONIC REACTOR

    DOEpatents

    Fermi, E.; Szilard, L.

    1957-09-24

    Reactors of the type employing plates of natural uranium in a moderator are discussed wherein the plates are um-formly disposed in parallel relationship to each other thereby separating the moderator material into distinct and individual layers. Each plate has an uninterrupted sunface area substantially equal to the cross-sectional area of the active portion of the reactor, the particular size of the plates and the volume ratio of moderator to uranium required to sustain a chain reaction being determinable from the known purity of these materials and other characteristics such as the predictable neutron losses due to the formation of radioactive elements of extremely high neutron capture cross section.

  9. NEUTRONIC REACTOR

    DOEpatents

    Wigner, E.P.; Weinberg, A.W.; Young, G.J.

    1958-04-15

    A nuclear reactor which uses uranium in the form of elongated tubes as fuel elements and liquid as a coolant is described. Elongated tubular uranium bodies are vertically disposed in an efficient neutron slowing agent, such as graphite, for example, to form a lattice structure which is disposed between upper and lower coolant tanks. Fluid coolant tubes extend through the uranium bodies and communicate with the upper and lower tanks and serve to convey the coolant through the uranium body. The reactor is also provided with means for circulating the cooling fluid through the coolant tanks and coolant tubes, suitable neutron and gnmma ray shields, and control means.

  10. Neutronic reactor

    DOEpatents

    Carleton, John T.

    1977-01-25

    A graphite-moderated nuclear reactor includes channels between blocks of graphite and also includes spacer blocks between adjacent channeled blocks with an axis of extension normal to that of the axis of elongation of the channeled blocks to minimize changes in the physical properties of the graphite as a result of prolonged neutron bombardment.

  11. Sonochemical Reactors.

    PubMed

    Gogate, Parag R; Patil, Pankaj N

    2016-10-01

    Sonochemical reactors are based on the generation of cavitational events using ultrasound and offer immense potential for the intensification of physical and chemical processing applications. The present work presents a critical analysis of the underlying mechanisms for intensification, available reactor configurations and overview of the different applications exploited successfully, though mostly at laboratory scales. Guidelines have also been presented for optimum selection of the important operating parameters (frequency and intensity of irradiation, temperature and liquid physicochemical properties) as well as the geometric parameters (type of reactor configuration and the number/position of the transducers) so as to maximize the process intensification benefits. The key areas for future work so as to transform the successful technique at laboratory/pilot scale into commercial technology have also been discussed. Overall, it has been established that there is immense potential for sonochemical reactors for process intensification leading to greener processing and economic benefits. Combined efforts from a wide range of disciplines such as material science, physics, chemistry and chemical engineers are required to harness the benefits at commercial scale operation.

  12. NEUTRONIC REACTORS

    DOEpatents

    Anderson, H.L.

    1958-10-01

    The design of control rods for nuclear reactors are described. In this design the control rod consists essentially of an elongated member constructed in part of a neutron absorbing material and having tube means extending therethrough for conducting a liquid to cool the rod when in use.

  13. NEUTRONIC REACTOR

    DOEpatents

    Creutz, E.C.; Ohlinger, L.A.; Weinberg, A.M.; Wigner, E.P.; Young, G.J.

    1959-10-27

    BS>A reactor cooled by water, biphenyl, helium, or other fluid with provision made for replacing the fuel rods with the highest plutonium and fission product content without disassembling the entire core and for promptly cooling the rods after their replacement in order to prevent build-up of heat from fission product activity is described.

  14. Neutronic reactor

    DOEpatents

    Wende, Charles W. J.

    1976-08-17

    A safety rod for a nuclear reactor has an inner end portion having a gamma absorption coefficient and neutron capture cross section approximately equal to those of the adjacent shield, a central portion containing materials of high neutron capture cross section and an outer end portion having a gamma absorption coefficient at least equal to that of the adjacent shield.

  15. Proximate weather patterns and spring green-up phenology effect Eurasian beaver (Castor fiber) body mass and reproductive success: the implications of climate change and topography.

    PubMed

    Campbell, Ruairidh D; Newman, Chris; Macdonald, David W; Rosell, Frank

    2013-04-01

    Low spring temperatures have been found to benefit mobile herbivores by reducing the rate of spring-flush, whereas high rainfall increases forage availability. Cold winters prove detrimental, by increasing herbivore thermoregulatory burdens. Here we examine the effects of temperature and rainfall variability on a temperate sedentary herbivore, the Eurasian beaver, Castor fiber, in terms of inter-annual variation in mean body weight and per territory offspring production. Data pertain to 198 individuals, over 11 years, using capture-mark-recapture. We use plant growth (tree cores) and fAPAR (a satellite-derived plant productivity index) to examine potential mechanisms through which weather conditions affect the availability and the seasonal phenology of beaver forage. Juvenile body weights were lighter after colder winters, whereas warmer spring temperatures were associated with lighter adult body weights, mediated by enhanced green-up phenology rates. Counter-intuitively, we observed a negative association between rainfall and body weight in juveniles and adults, and also with reproductive success. Alder, Alnus incana, (n = 68) growth rings (principal beaver food in the study area) exhibited a positive relationship with rainfall for trees growing at elevations >2 m above water level, but a negative relationship for trees growing <0.5 m. We deduce that temperature influences beavers at the landscape scale via effects on spring green-up phenology and winter thermoregulation. Rainfall influences beavers at finer spatial scales through topographical interactions with plant growth, where trees near water level, prone to water logging, producing poorer forage in wetter years. Unlike most other herbivores, beavers are an obligate aquatic species that utilize a restricted 'central-place' foraging range, limiting their ability to take advantage of better forage growth further from water during wetter years. With respect to anthropogenic climate change, interactions between

  16. An 11 000-year-long record of fire and vegetation history at Beaver Lake, Oregon, central Willamette Valley

    NASA Astrophysics Data System (ADS)

    Walsh, Megan K.; Pearl, Christopher A.; Whitlock, Cathy; Bartlein, Patrick J.; Worona, Marc A.

    2010-05-01

    High-resolution macroscopic charcoal and pollen analysis were used to reconstruct an 11 000-year-long record of fire and vegetation history from Beaver Lake, Oregon, the first complete Holocene paleoecological record from the floor of the Willamette Valley. In the early Holocene (ca 11 000-7500 calendar years before present [cal yr BP]), warmer, drier summers than at present led to the establishment of xeric woodland of Quercus, Corylus, and Pseudotsuga near the site. Disturbances (i.e., floods, fires) were common at this time and as a result Alnus rubra grew nearby. High fire frequency occurred in the early Holocene from ca 11 200-9300 cal yr BP. Riparian forest and wet prairie developed in the middle Holocene (ca 7500 cal yr BP), likely the result of a decrease in the frequency of flooding and a shift to effectively cooler, wetter conditions than before. The vegetation at Beaver Lake remained generally unchanged into the late Holocene (from 4000 cal yr BP to present), with the exception of land clearance associated with Euro-American settlement of the valley (ca 160 cal yr BP). Middle-to-late Holocene increases in fire frequency, coupled with abrupt shifts in fire-episode magnitude and charcoal composition, likely indicate the influence anthropogenic burning near the site. The paleoecological record from Beaver Lake, and in particular the general increase in fire frequency over the last 8500 years, differs significantly from other low-elevation sites in the Pacific Northwest, which suggests that local controls (e.g., shifts in vegetation structure, intensification of human land-use), rather than regional climatic controls, more strongly influenced its environmental history.

  17. An 11 000-year-long record of fire and vegetation history at Beaver Lake, Oregon, central Willamette Valley

    USGS Publications Warehouse

    Walsh, Megan K.; Pearl, Christopher A.; Whitlock, Cathy; Bartlein, Patrick J.; Worona, Marc A.

    2010-01-01

    High-resolution macroscopic charcoal and pollen analysis were used to reconstruct an 11??000-year-long record of fire and vegetation history from Beaver Lake, Oregon, the first complete Holocene paleoecological record from the floor of the Willamette Valley. In the early Holocene (ca 11??000-7500 calendar years before present [cal??yr??BP]), warmer, drier summers than at present led to the establishment of xeric woodland of Quercus, Corylus, and Pseudotsuga near the site. Disturbances (i.e., floods, fires) were common at this time and as a result Alnus rubra grew nearby. High fire frequency occurred in the early Holocene from ca 11??200-9300??cal??yr??BP. Riparian forest and wet prairie developed in the middle Holocene (ca 7500??cal??yr??BP), likely the result of a decrease in the frequency of flooding and a shift to effectively cooler, wetter conditions than before. The vegetation at Beaver Lake remained generally unchanged into the late Holocene (from 4000??cal??yr??BP to present), with the exception of land clearance associated with Euro-American settlement of the valley (ca 160??cal??yr BP). Middle-to-late Holocene increases in fire frequency, coupled with abrupt shifts in fire-episode magnitude and charcoal composition, likely indicate the influence anthropogenic burning near the site. The paleoecological record from Beaver Lake, and in particular the general increase in fire frequency over the last 8500??years, differs significantly from other low-elevation sites in the Pacific Northwest, which suggests that local controls (e.g., shifts in vegetation structure, intensification of human land-use), rather than regional climatic controls, more strongly influenced its environmental history. ?? 2010 Elsevier Ltd.

  18. Sunlight and the 10-year incidence of age-related maculopathy: the Beaver Dam Eye Study.

    PubMed

    Tomany, Sandra C; Cruickshanks, Karen J; Klein, Ronald; Klein, Barbara E K; Knudtson, Michael D

    2004-05-01

    To examine the association of sunlight exposure and indicators of sun sensitivity with the 10-year incidence of age-related maculopathy (ARM). Population-based cohort study. We included persons aged 43 to 86 years at the baseline examination from 1988 to 1990, living in Beaver Dam, Wis, of whom 3684 persons underwent 5-year follow-up and 2764 underwent 10-year follow-up. Data on sun exposure and indicators of sun sensitivity were obtained from a standardized questionnaire administered at baseline and/or follow-up. We determined ARM status by grading stereoscopic color fundus photographs using the Wisconsin Age-Related Maculopathy Grading System. Incidence and progression of ARM. While controlling for age and sex, we found that participants exposed to the summer sun for more than 5 hours a day during their teens, in their 30s, and at the baseline examination were at a higher risk of developing increased retinal pigment (risk ratio [RR], 2.99; 95% confidence interval [CI], 1.18-7.60; P =.02) and early ARM (RR, 2.20; 95% CI, 1.02-4.73; P =.04) [corrected] by 10 years than those exposed less than 2 hours per day during the same periods. In participants reporting the highest summer sun exposure levels in their teens and 30s, the use of hats and sunglasses at least half the time during the same periods was associated with a decreased risk of developing soft indistinct drusen (RR, 0.55; 95% CI, 0.33-0.90; P =.02) and retinal pigment epithelial depigmentation (RR, 0.51; 95% CI, 0.29-0.91; P =.02). Participants who experienced more than 10 severe sunburns during their youth were more likely than those who experienced 1 or no burn to develop drusen with a 250-microm diameter or larger (RR, 2.52; 95% CI, 1.29-4.94 [corrected] P =.01) by the 10-year examination. No relationships were found between UV-B exposure, winter leisure time spent outdoors, skin sun sensitivity, or number of bad sunburns experienced by the time of the baseline examination and the 10-year incidence and

  19. The influence of mean climate trends and climate variance on beaver survival and recruitment dynamics.

    PubMed

    Campbell, Ruairidh D; Nouvellet, Pierre; Newman, Chris; Macdonald, David W; Rosell, Frank

    2012-09-01

    Ecologists are increasingly aware of the importance of environmental variability in natural systems. Climate change is affecting both the mean and the variability in weather and, in particular, the effect of changes in variability is poorly understood. Organisms are subject to selection imposed by both the mean and the range of environmental variation experienced by their ancestors. Changes in the variability in a critical environmental factor may therefore have consequences for vital rates and population dynamics. Here, we examine ≥90-year trends in different components of climate (precipitation mean and coefficient of variation (CV); temperature mean, seasonal amplitude and residual variance) and consider the effects of these components on survival and recruitment in a population of Eurasian beavers (n = 242) over 13 recent years. Within climatic data, no trends in precipitation were detected, but trends in all components of temperature were observed, with mean and residual variance increasing and seasonal amplitude decreasing over time. A higher survival rate was linked (in order of influence based on Akaike weights) to lower precipitation CV (kits, juveniles and dominant adults), lower residual variance of temperature (dominant adults) and lower mean precipitation (kits and juveniles). No significant effects were found on the survival of nondominant adults, although the sample size for this category was low. Greater recruitment was linked (in order of influence) to higher seasonal amplitude of temperature, lower mean precipitation, lower residual variance in temperature and higher precipitation CV. Both climate means and variance, thus proved significant to population dynamics; although, overall, components describing variance were more influential than those describing mean values. That environmental variation proves significant to a generalist, wide-ranging species, at the slow end of the slow-fast continuum of life histories, has broad implications for

  20. Landscape consequences of natural gas extraction in Beaver and Butler Counties, Pennsylvania, 2004-2010

    USGS Publications Warehouse

    Roig-Silva, Coral M.; Slonecker, E. Terry; Milheim, Lesley E.; Malizia, Alexander R.

    2013-01-01

    Increased demands for cleaner burning energy, coupled with the relatively recent technological advances in accessing unconventional hydrocarbon-rich geologic formations, have led to an intense effort to find and extract natural gas from various underground sources around the country. One of these sources, the Marcellus Shale, located in the Allegheny Plateau, is currently undergoing extensive drilling and production. The technology used to extract gas in the Marcellus Shale is known as hydraulic fracturing and has garnered much attention because of its use of large amounts of fresh water, its use of proprietary fluids for the hydraulic-fracturing process, its potential to release contaminants into the environment, and its potential effect on water resources. Nonetheless, development of natural gas extraction wells in the Marcellus Shale is only part of the overall natural gas story in this area of Pennsylvania. Conventional natural gas wells, which sometimes use the same technique, are commonly located in the same general area as the Marcellus Shale and are frequently developed in clusters across the landscape. The combined effects of these two natural gas extraction methods create potentially serious patterns of disturbance on the landscape. This document quantifies the landscape changes and consequences of natural gas extraction for Beaver County and Butler County in Pennsylvania between 2004 and 2010. Patterns of landscape disturbance related to natural gas extraction activities were collected and digitized using National Agriculture Imagery Program (NAIP) imagery for 2004, 2005/2006, 2008, and 2010. The disturbance patterns were then used to measure changes in land cover and land use using the National Land Cover Database (NLCD) of 2001. A series of landscape metrics is also used to quantify these changes and is included in this publication.

  1. Ground-water-quality data for selected wells in the Beaver Creek watershed, West Tennessee

    USGS Publications Warehouse

    Williams, S.D.

    1996-01-01

    In 1993 the U.S. Geological Survey, in cooperation with the Tennessee Department of Environment and Conservation (TDEC), began an investigation of the quality of ground water in the Beaver Creek watershed in West Tennessee. A total of 408 water samples were collected from 91 wells during 5 sampling periods in 1994. Water samples were analyzed for selected water-quality properties, fecal coliform and streptococci bacteria, nutrients, and major inorganic constituents. Selected well- construction data and information on potential sources of contamination were also collected for the 91 wells sampled. Nitrate concentrations (measured as NO3) ranged from a detection limit of 0.1 to 91 milligrams per liter (mg/L). Nitrate concentrations exceeding 13 mg/L were detected in 71 of the samples collected. Nitrate concentrations in water samples collected from three wells exceeded the TDEC primary drinking water standard of 44 mg/L for nitrate (measured as NO3). Nitrite (measured as NO2), ammonium (measured as NH4), and orthophosphate (measured as PO4) concentrations in samples were generally less than 0.1 mg/L (detection limit). Fecal coliform bacteria were detected in 33 of the 408 water samples collected. Samples from 21 of the 91 wells contained fecal coliform bacteria during one or more of the five sampling periods. Fecal streptococci bacteria were detected in 123 of the 408 samples. Samples from 59 wells contained fecal streptococci bacteria during one or more of the five sampling periods.

  2. But What About Trees and Beavers? Simplicity, Complexity and Benchmarks for Landscape Evolution Models

    NASA Astrophysics Data System (ADS)

    Armitage, J. J.

    2016-12-01

    We cannot see the forest because of the trees. There is perhaps some truth in this joke when it comes to the study of surface processes. The surface of the Earth is shaped by multiple processes on multiple scales. This is a statement of the obvious. The deformation of the mantle deep within the interior of the Earth is controlled by multiple processes on multiple scales. Likewise, obvious. For studies of the Earth's interior it is accepted that we can approximate the deformation of the mantle by a viscous flow law. The exact form of this flow is uncertain, yet the basic assumption is considered reasonable, and so numerical models are benchmarked against laboratory experiments and applied to Earth-scale questions. For surface processes, or landscape evolution models (LEMs), such an accepted basic starting point does not exist. There is no accepted approximation for sediment transport. No LEM is benchmarked, no benchmark exists. Instead we have a tendency to focus on things we can see: trees or even beavers. In this presentation I will explore the behaviour two classic idealised LEMs, the stream power law and a sediment transport model first proposed by Smith and Bretherton. I will show that that these models behave in a diagnostically different manner to change in surface run-off, where the response time is a function of slope and water flux exponents. The observation that the system response has a form that is a function of the assumed transport law could provide a benchmark for such simple numerical models, as a similar response is observed in laboratory scale experiments. This could then be the starting point for introducing complexity.

  3. Linkage Analysis of Quantitative Refraction and Refractive Errors in the Beaver Dam Eye Study

    PubMed Central

    Duggal, Priya; Lee, Kristine E.; Cheng, Ching-Yu; Klein, Ronald; Bailey-Wilson, Joan E.; Klein, Barbara E. K.

    2011-01-01

    Purpose. Refraction, as measured by spherical equivalent, is the need for an external lens to focus images on the retina. While genetic factors play an important role in the development of refractive errors, few susceptibility genes have been identified. However, several regions of linkage have been reported for myopia (2q, 4q, 7q, 12q, 17q, 18p, 22q, and Xq) and for quantitative refraction (1p, 3q, 4q, 7p, 8p, and 11p). To replicate previously identified linkage peaks and to identify novel loci that influence quantitative refraction and refractive errors, linkage analysis of spherical equivalent, myopia, and hyperopia in the Beaver Dam Eye Study was performed. Methods. Nonparametric, sibling-pair, genome-wide linkage analyses of refraction (spherical equivalent adjusted for age, education, and nuclear sclerosis), myopia and hyperopia in 834 sibling pairs within 486 extended pedigrees were performed. Results. Suggestive evidence of linkage was found for hyperopia on chromosome 3, region q26 (empiric P = 5.34 × 10−4), a region that had shown significant genome-wide evidence of linkage to refraction and some evidence of linkage to hyperopia. In addition, the analysis replicated previously reported genome-wide significant linkages to 22q11 of adjusted refraction and myopia (empiric P = 4.43 × 10−3 and 1.48 × 10−3, respectively) and to 7p15 of refraction (empiric P = 9.43 × 10−4). Evidence was also found of linkage to refraction on 7q36 (empiric P = 2.32 × 10−3), a region previously linked to high myopia. Conclusions. The findings provide further evidence that genes controlling refractive errors are located on 3q26, 7p15, 7p36, and 22q11. PMID:21571680

  4. Linkage analysis of quantitative refraction and refractive errors in the Beaver Dam Eye Study.

    PubMed

    Klein, Alison P; Duggal, Priya; Lee, Kristine E; Cheng, Ching-Yu; Klein, Ronald; Bailey-Wilson, Joan E; Klein, Barbara E K

    2011-07-13

    Refraction, as measured by spherical equivalent, is the need for an external lens to focus images on the retina. While genetic factors play an important role in the development of refractive errors, few susceptibility genes have been identified. However, several regions of linkage have been reported for myopia (2q, 4q, 7q, 12q, 17q, 18p, 22q, and Xq) and for quantitative refraction (1p, 3q, 4q, 7p, 8p, and 11p). To replicate previously identified linkage peaks and to identify novel loci that influence quantitative refraction and refractive errors, linkage analysis of spherical equivalent, myopia, and hyperopia in the Beaver Dam Eye Study was performed. Nonparametric, sibling-pair, genome-wide linkage analyses of refraction (spherical equivalent adjusted for age, education, and nuclear sclerosis), myopia and hyperopia in 834 sibling pairs within 486 extended pedigrees were performed. Suggestive evidence of linkage was found for hyperopia on chromosome 3, region q26 (empiric P = 5.34 × 10(-4)), a region that had shown significant genome-wide evidence of linkage to refraction and some evidence of linkage to hyperopia. In addition, the analysis replicated previously reported genome-wide significant linkages to 22q11 of adjusted refraction and myopia (empiric P = 4.43 × 10(-3) and 1.48 × 10(-3), respectively) and to 7p15 of refraction (empiric P = 9.43 × 10(-4)). Evidence was also found of linkage to refraction on 7q36 (empiric P = 2.32 × 10(-3)), a region previously linked to high myopia. The findings provide further evidence that genes controlling refractive errors are located on 3q26, 7p15, 7p36, and 22q11.

  5. Olfactory impairment in an adult population: the Beaver Dam Offspring Study.

    PubMed

    Schubert, Carla R; Cruickshanks, Karen J; Fischer, Mary E; Huang, Guan-Hua; Klein, Barbara E K; Klein, Ronald; Pankow, James S; Nondahl, David M

    2012-05-01

    The objective of this study was to determine the prevalence of olfactory impairment and associated risk factors and the effects of olfactory impairment on dietary choices and quality of life. Odor identification was measured in 2838 participants aged 21-84 years (mean 49 years) in the Beaver Dam Offspring Study. The overall prevalence of olfactory impairment was 3.8%, increased with age (from 0.6% in those<35 years to 13.9% among those≥65 years) and was more common in men than women. In a multivariate model age (odds ratio [OR]=1.48, 95% confidence interval [CI]=1.33, 1.64 for every 5-year increase), nasal polyps or deviated septum (OR=2.69, 95% CI=1.62, 4.48), ankle-brachial index<0.9 (OR=3.62, 95% CI=1.45, 9.01), and smoking (women only) (OR=2.43, 95% CI=1.19, 4.98 ever smoked vs. never) were associated with an increased odds of olfactory impairment, whereas higher household income, ≥$50,000 versus <$50,000 per year, was associated with a decreased odds of olfactory impairment (OR=0.48, 95% CI=0.31, 0.73). Participants with olfactory impairment were less likely to report that food tasted as good as it used to, or that they experienced food flavors the same. There was no association between olfactory impairment and general health-related quality of life, depressive symptoms, or dietary choices. The prevalence of olfactory impairment was low in this largely middle-aged cohort, and some factors associated with olfactory impairment are potentially modifiable.

  6. The influence of hydrologic connectivity on ecosystem metabolism and nitrate uptake in an active beaver meadow

    NASA Astrophysics Data System (ADS)

    Wegener, P.; Covino, T. P.; Wohl, E.; Kampf, S. K.; Lacy, S.

    2015-12-01

    Wetlands have been widely demonstrated to provide important watershed services, such as the sequestration of carbon (C) and removal of nitrate (NO3-) from through-flowing water. Hydrologic connectivity (degree of water and associated material exchange) between floodplain water bodies (e.g., side channels, ponds) and the main channel influence rates of C accumulation and NO3- uptake, and the degree to which wetlands contribute to enhanced water quality at the catchment scale. However, environmental engineers have largely ignored the role of hydrologic connectivity in providing essential ecosystem services, and constructed wetlands are commonly built using compacted clay and berms that result in less groundwater and surface water exchange than observed in natural wetlands. In a study of an active beaver meadow (multithreaded, riparian wetland) in Rocky Mountain National Park, CO, we show how shifts in hydrology (connectivity, residence times, flow paths) from late spring snowmelt (high connectivity) to autumn/winter baseflow (low connectivity) influence ecosystem metabolism metrics (e.g., gross primary production, ecosystem respiration, and net ecosystem productivity) and NO3- uptake rates. We use a combination of mixing analyses, tracer tests, and hydrometric methods to evaluate shifts in surface and subsurface hydrologic connections between floodplain water bodies from snowmelt to baseflow. In the main channel and three floodplain water bodies, we quantify metabolism metrics and NO3- uptake kinetics across shifting flow regimes. Results from our research indicate that NO3- uptake and metabolism dynamics respond to changing levels of hydrologic connectivity to the main channel, emphasizing the importance of incorporating connectivity in wetland mitigation practices that seek to enhance water quality at the catchment scale.

  7. NUCLEAR REACTOR

    DOEpatents

    Grebe, J.J.

    1959-12-15

    A reactor which is particularly adapted tu serve as a heat source for a nuclear powered alrcraft or rocket is described. The core of this reactor consists of a porous refractory modera;or body which is impregnated with fissionable nuclei. The core is designed so that its surface forms tapered inlet and outlet ducts which are separated by the porous moderator body. In operation a gaseous working fluid is circulated through the inlet ducts to the surface of the moderator, enters and passes through the porous body, and is heated therein. The hot gas emerges into the outlet ducts and is available to provide thrust. The principle advantage is that tremendous quantities of gas can be quickly heated without suffering an excessive pressure drop.

  8. REACTOR UNLOADING

    DOEpatents

    Leverett, M.C.

    1958-02-18

    This patent is related to gas cooled reactors wherein the fuel elements are disposed in vertical channels extending through the reactor core, the cooling gas passing through the channels from the bottom to the top of the core. The invention is a means for unloading the fuel elements from the core and comprises dump values in the form of flat cars mounted on wheels at the bottom of the core structure which support vertical stacks of fuel elements. When the flat cars are moved, either manually or automatically, for normal unloading purposes, or due to a rapid rise in the reproduction ratio within the core, the fuel elements are permtted to fall by gravity out of the core structure thereby reducing the reproduction ratio or stopping the reaction as desired.

  9. NEUTRONIC REACTOR

    DOEpatents

    Wade, E.J.

    1958-09-16

    This patent relates to a reflector means for a neutronic reactor. A reflector comprised of a plurality of vertically movable beryllium control members is provided surrounding the sides of the reactor core. An absorber of fast neutrons comprised of natural uramum surrounds the reflector. An absorber of slow neutrons surrounds the absorber of fast neutrons and is formed of a plurality of beryllium blocks having natural uranium members distributcd therethrough. in addition, a movable body is positioned directly below the core and is comprised of a beryllium reflector and an absorbing member attached to the botiom thereof, the absorbing member containing a substance selected from the goup consisting of natural urantum and Th/sup 232/.

  10. REACTOR MONITORING

    DOEpatents

    Bugbee, S.J.; Hanson, V.F.; Babcock, D.F.

    1959-02-01

    A neutron density inonitoring means for reactors is described. According to this invention a tunnel is provided beneath and spaced from the active portion of the reactor and extends beyond the opposite faces of the activc portion. Neutron beam holes are provided between the active portion and the tunnel and open into the tunnel near the middle thereof. A carriage operates back and forth in the tunnel and is adapted to convey a neutron detector, such as an ion chamber, and position it beneath one of the neutron beam holes. This arrangement affords convenient access of neutron density measuring instruments to a location wherein direct measurement of neutron density within the piles can be made and at the same time affords ample protection to operating personnel.

  11. Nuclear reactor

    DOEpatents

    Wade, Elman E.

    1979-01-01

    A nuclear reactor including two rotatable plugs and a positive top core holddown structure. The top core holddown structure is divided into two parts: a small core cover, and a large core cover. The small core cover, and the upper internals associated therewith, are attached to the small rotating plug, and the large core cover, with its associated upper internals, is attached to the large rotating plug. By so splitting the core holddown structures, under-the-plug refueling is accomplished without the necessity of enlarging the reactor pressure vessel to provide a storage space for the core holddown structure during refueling. Additionally, the small and large rotating plugs, and their associated core covers, are arranged such that the separation of the two core covers to permit rotation is accomplished without the installation of complex lifting mechanisms.

  12. NUCLEAR REACTOR

    DOEpatents

    Treshow, M.

    1958-08-19

    A neuclear reactor is described of the heterogeneous type and employing replaceable tubular fuel elements and heavy water as a coolant and moderator. A pluraltty of fuel tubesa having their axes parallel, extend through a tank type pressure vessel which contatns the liquid moderator. The fuel elements are disposed within the fuel tubes in the reaetive portion of the pressure vessel during normal operation and the fuel tubes have removable plug members at each end to permit charging and discharging of the fuel elements. The fuel elements are cylindrical strands of jacketed fissionable material having helical exterior ribs. A bundle of fuel elements are held within each fuel tube with their longitudinal axes parallel, the ribs serving to space them apart along their lengths. Coolant liquid is circulated through the fuel tubes between the spaced fuel elements. Suitable control rod and monitoring means are provided for controlling the reactor.

  13. Neutronic reactor

    DOEpatents

    Lewis, Warren R.

    1978-05-30

    A graphite-moderated, water-cooled nuclear reactor including a plurality of rectangular graphite blocks stacked in abutting relationship in layers, alternate layers having axes which are normal to one another, alternate rows of blocks in alternate layers being provided with a channel extending through the blocks, said channeled blocks being provided with concave sides and having smaller vertical dimensions than adjacent blocks in the same layer, there being nuclear fuel in the channels.

  14. NUCLEAR REACTORS

    DOEpatents

    Long, E.; Ashby, J.W.

    1958-09-16

    ABS>A graphite moderator structure is presented for a nuclear reactor compriscd of an assembly of similarly orientated prismatic graphite blocks arranged on spaced longitudinal axes lying in common planes wherein the planes of the walls of the blocks are positioned so as to be twisted reintive to the planes of said axes so thatthe unlmpeded dtrect paths in direction wholly across the walls of the blocks are limited to the width of the blocks plus spacing between the blocks.

  15. NUCLEAR REACTOR

    DOEpatents

    Grebe, J.J.

    1961-01-24

    A core structure for neutronic reactors adapted for the propulsion of aircraft and rockets is offered. The core is designed for cooling by gaseous media, and comprises a plurality of hollow tapered tubular segments of a porous moderating material impregniated with fissionable fuel nested about a common axis. Alternate ends of the segments are joined. In operation a coolant gas passes through the porous structure and is heated.

  16. NUCLEAR REACTORS

    DOEpatents

    Koch, L.J.; Rice, R.E. Jr.; Denst, A.A.; Rogers, A.J.; Novick, M.

    1961-12-01

    An active portion assembly for a fast neutron reactor is described wherein physical distortions resulting in adverse changes in the volume-to-mass ratio are minimized. A radially expandable locking device is disposed within a cylindrical tube within each fuel subassembly within the active portion assembly, and clamping devices expandable toward the center of the active portion assembly are disposed around the periphery thereof. (AEC)

  17. REACTOR CONTROL

    DOEpatents

    Ruano, W.J.

    1957-12-10

    This patent relates to nuclear reactors of the type which utilize elongited rod type fuel elements immersed in a liquid moderator and shows a design whereby control of the chain reaction is obtained by varying the amount of moderator or reflector material. A central tank for containing liquid moderator and fuel elements immersed therein is disposed within a surrounding outer tank providing an annular space between the two tanks. This annular space is filled with liquid moderator which functions as a reflector to reflect neutrons back into the central reactor tank to increase the reproduction ratio. Means are provided for circulating and cooling the moderator material in both tanks and additional means are provided for controlling separately the volume of moderator in each tank, which latter means may be operated automatically by a neutron density monitoring device. The patent also shows an arrangement for controlling the chain reaction by injecting and varying an amount of poisoning material in the moderator used in the reflector portion of the reactor.

  18. Space reactors

    NASA Astrophysics Data System (ADS)

    Ranken, W. A.

    1983-01-01

    Progress in design studies and technology for the SP-100 Project - successor to the Space Power Advanced Reactor (SPAR) Project - is reported for the period October 1, 1981 to March 31, 1982. The basis for selecting a high-temperature, UO2-fueled, heat-pipe-cooled reactor with a thermoelectric conversion system as the 100/kW-sub e/ reference design has been reviewed. Although no change has been made in the general concept, design studies have been done to investigate various reactor/conversion system coupling methods and core design modifications. Thermal and mechanical finite element modeling and three dimensional Monte Carlo analysis of a core with individual finned fuel elements are reported. Studies of unrestrained fuel irradiation data are discussed that are relevant both to the core modeling work and to the design and fabrication of the first in-pile irradiation test, which is also reported. Work on lithium-filled core heat pipe development is described, including the attainment of 15.6 kW/sub t/ operation at 1525 K for a 2-m-long heat pipe with a 15.7-mm outside diameter. The successful operation of a 5.5-m-long, lightweight potassium/titanium heat pipe at 760 K is described, and test results of a thermoelectric module with GaP-modified SiGe thermoelectric elements are presented.

  19. Socio-ecological features other than sex affect habitat selection in the socially obligate monogamous Eurasian beaver.

    PubMed

    Steyaert, Sam M J G; Zedrosser, Andreas; Rosell, Frank

    2015-12-01

    Habitat selection is a context-dependent mechanism, in which both the internal state as well as external factors affect the behavior and decisions of an individual. This is well known for polygamous mammals, which are typically sexually dimorphic, and often express great variability in behavior and habitat selection between individuals as well between the sexes. Among monogamous mammals, however, variability in habitat selection should be explained by group characteristics and the presence of offspring rather than by sex. We evaluated this hypothesis in a socially monogamous rodent, the Eurasian beaver (Castor fiber), in a saturated Norwegian population. For the first time in this species we applied GPS tracking devices (N = 22 adult beavers, in 15 territories, 2009-2013), and used resource selection functions (i) to document population-wide habitat selection and the importance of 'territory' therein, and (ii) to evaluate which socio-ecological factors explained potential individual differences in habitat selection. We found that variation in habitat selection was stronger between territories than between years or individuals nested by territory. We identified that family size and the presence of kits, but not sex, explained individual variation in habitat selection. Adults with kits and/or larger families tended to exhibit low risk-taking behavior (avoiding human-related variables such as roads, buildings, and agricultural land), and stayed close to their main lodge (parental care). Our results show that habitat selection is a context-dependent mechanism even in a species which expresses very little behavioral and morphological dimorphism.

  20. Isolation and antimicrobial susceptibility of Streptococcus castoreus isolated from carcasses of European beavers (Castor fiber) in Germany.

    PubMed

    Schulze, Christoph; Kutzer, Peter; Winterhoff, Nora; Engelhardt, Andreas; Bilk, Sabine; Teubner, Jens

    2015-01-01

    Streptococcus (S.) castoreus was isolated from seven beavers (Castor fiber), which were found dead in the federal state of Brandenburg, Germany, and submitted to the Berlin-Brandenburg State laboratory for post mortem diagnostics. The isolates originated from various inflammatory processes where they were associated with other Gram negative and Gram positive aerobic and/or anaerobic bacteria (i. e. Actinobacillus sp., species of the Actinomycetaceae family, coliform bacteria, Fusobacterium sp., Prevotella sp.), but also from cloacal swabs. Testing their antimicrobial susceptibility, all S. castoreus isolates and the type strain S. castoreus (DSM 17536) were classified as being susceptible to penicillin G, ampicillin, amoxicillin-clavulanic acid, 1st generation cephalosporins, erythromycin, tetracycline, and chloramphenicole but intermediate to gentamicin. Considering both the polymicrobial flora isolated from the inflamed tissues and the fact that antimicrobials of a narrow spectrum (namely penicillins, 1st generation cephalosporins, macrolids and lincosamids) can be toxic to rodents, chloramphenicol might be a suitable drug for treatment of beavers suffering from S. castoreus (mixed)-bacterial infections.

  1. Light and Electron Microscopy of the European Beaver (Castor fiber) Stomach Reveal Unique Morphological Features with Possible General Biological Significance

    PubMed Central

    Petryński, Wojciech; Palkowska, Katarzyna; Prusik, Magdalena; Targońska, Krystyna; Giżejewski, Zygmunt; Przybylska-Gornowicz, Barbara

    2014-01-01

    Anatomical, histological, and ultrastructural studies of the European beaver stomach revealed several unique morphological features. The prominent attribute of its gross morphology was the cardiogastric gland (CGG), located near the oesophageal entrance. Light microscopy showed that the CGG was formed by invaginations of the mucosa into the submucosa, which contained densely packed proper gastric glands comprised primarily of parietal and chief cells. Mucous neck cells represented <0.1% of cells in the CGG gastric glands and 22–32% of cells in the proper gastric glands of the mucosa lining the stomach lumen. These data suggest that chief cells in the CGG develop from undifferentiated cells that migrate through the gastric gland neck rather than from mucous neck cells. Classical chief cell formation (i.e., arising from mucous neck cells) occurred in the mucosa lining the stomach lumen, however. The muscularis around the CGG consisted primarily of skeletal muscle tissue. The cardiac region was rudimentary while the fundus/corpus and pyloric regions were equally developed. Another unusual feature of the beaver stomach was the presence of specific mucus with a thickness up to 950 µm (in frozen, unfixed sections) that coated the mucosa. Our observations suggest that the formation of this mucus is complex and includes the secretory granule accumulation in the cytoplasm of pit cells, the granule aggregation inside cells, and the incorporation of degenerating cells into the mucus. PMID:24727802

  2. Light and electron microscopy of the European beaver (Castor fiber) stomach reveal unique morphological features with possible general biological significance.

    PubMed

    Ziółkowska, Natalia; Lewczuk, Bogdan; Petryński, Wojciech; Palkowska, Katarzyna; Prusik, Magdalena; Targońska, Krystyna; Giżejewski, Zygmunt; Przybylska-Gornowicz, Barbara

    2014-01-01

    Anatomical, histological, and ultrastructural studies of the European beaver stomach revealed several unique morphological features. The prominent attribute of its gross morphology was the cardiogastric gland (CGG), located near the oesophageal entrance. Light microscopy showed that the CGG was formed by invaginations of the mucosa into the submucosa, which contained densely packed proper gastric glands comprised primarily of parietal and chief cells. Mucous neck cells represented <0.1% of cells in the CGG gastric glands and 22-32% of cells in the proper gastric glands of the mucosa lining the stomach lumen. These data suggest that chief cells in the CGG develop from undifferentiated cells that migrate through the gastric gland neck rather than from mucous neck cells. Classical chief cell formation (i.e., arising from mucous neck cells) occurred in the mucosa lining the stomach lumen, however. The muscularis around the CGG consisted primarily of skeletal muscle tissue. The cardiac region was rudimentary while the fundus/corpus and pyloric regions were equally developed. Another unusual feature of the beaver stomach was the presence of specific mucus with a thickness up to 950 µm (in frozen, unfixed sections) that coated the mucosa. Our observations suggest that the formation of this mucus is complex and includes the secretory granule accumulation in the cytoplasm of pit cells, the granule aggregation inside cells, and the incorporation of degenerating cells into the mucus.

  3. Nuclear Reactors. Revised.

    ERIC Educational Resources Information Center

    Hogerton, John F.

    This publication is one of a series of information booklets for the general public published by the United States Atomic Energy Commission. Among the topics discussed are: How Reactors Work; Reactor Design; Research, Teaching, and Materials Testing; Reactors (Research, Teaching and Materials); Production Reactors; Reactors for Electric Power…

  4. Changes in flow in the Beaver-North Canadian River basin upstream from Canton Lake, western Oklahoma

    USGS Publications Warehouse

    Wahl, Kenneth L.; Tortorelli, Robert L.

    1997-01-01

    This report presents the results of an evaluation of hydrologic data for the Beaver-North Canadian River basin upstream from Canton Lake in western Oklahoma. It examines the climatic and hydrologic data for evidence of trends. The hydrologic data examined includes total annual flow, base flow, and annual peak discharges. This study was conducted to determine if there is evidence of trends present in hydrologic and climatic data. All available streamflow-gaging station data, with at least 10 or more years of record, were examined for trends. In addition, the data were divided into an 'early' period (ending in 1971), representing conditions before ground-water levels had declined appreciably, and a 'recent' period (1978-1994), reflecting the condition of declining ground-water levels, including the effects of storage reservoirs. Tests for trend, moving averages, and comparisons of median and average flows for an early period (ending in 1971) with those for the recent period (1978-1994) show that the total annual volume of flow and the magnitudes of instantaneous annual peak discharges measured at most gaging stations in the Beaver- North Canadian River basin have decreased in recent years. Precipitation records for the panhandle, however, show no corresponding changes. The changes in flow are most pronounced in the headwaters upstream from Woodward, but also are evident at Woodward and near Seiling, which represents the inflow to Canton Lake. The average annual discharge decreased between the early period and the recent period by the following amounts: near Guymon, 18,000 acre-feet; at Beaver, 68,000 acre-feet; at Woodward, 72,000 acre-feet; and near Seiling, 63,000 acre-feet. These decreases, expressed as a percentage of the average flows for the early period, were 91 percent near Guymon, 82 percent at Beaver, 49 percent at Woodward, and 37 percent near Seiling. The medians of the annual peak discharges decreased from the early period to the recent period by the

  5. Antigen detection, rabies virus isolation, and Q-PCR in the quantification of viral load in a natural infection of the North American beaver (Castor canadensis).

    PubMed

    Morgan, Shannon M D; Pouliott, Craig E; Rudd, Robert J; Davis, April D

    2015-01-01

    All mammals are believed susceptible to rabies virus infection, yet transmission from nonreservoir hosts to humans is uncommon. However, interactions between nonreservoir hosts and humans occur frequently and risk of exposure increases where rabies is enzootic. We describe rabies and apparent pantropism of rabies virus in a beaver (Castor canadensis).

  6. The influence of fall-spawning coho salmon (Oncorhynchus kisutch) on growth and production of juvenile coho salmon rearing in beaver ponds on the Copper River Delta, Alaska.

    Treesearch

    Dirk W. Lang; Gordon H. Reeves; James D. Hall; Mark S. Wipfli

    2006-01-01

    This study examined the influence of fall-spawning coho salmon (Oncorhynchrcs kisutch) on the density, growth rate, body condition, and survival to outmigration of juvenile coho salmon on the Copper River Delta, Alaska, USA. During the fall of 1999 and 2000, fish rearing in beaver ponds that received spawning salmon were compared with fish from...

  7. A Study to Determine the Acceptance and Effectiveness of an Experimental Mobile Unit Which Serves Milford, Beaver, Delta, and Fillmore in Southern Utah.

    ERIC Educational Resources Information Center

    Widmer, Grant W.

    The study determined the acceptance by high school students of a mobile-classroom approach to the teaching of electronics. Also investigated was the effectiveness of this teaching method with high school students in the southern Utah communities of Milford, Beaver, Delta, and Fillmore during the 1968-69 school year. As ascertained by the attitude…

  8. Nuclear reactor

    DOEpatents

    Pennell, William E.; Rowan, William J.

    1977-01-01

    A nuclear reactor in which the core components, including fuel-rod assemblies, control-rod assemblies, fertile rod-assemblies, and removable shielding assemblies, are supported by a plurality of separate inlet modular units. These units are referred to as inlet module units to distinguish them from the modules of the upper internals of the reactor. The modular units are supported, each removable independently of the others, in liners in the supporting structure for the lower internals of the reactor. The core assemblies are removably supported in integral receptacles or sockets of the modular units. The liners, units, sockets and assmblies have inlet openings for entry of the fluid. The modular units are each removably mounted in the liners with fluid seals interposed between the opening in the liner and inlet module into which the fluid enters and the upper and lower portion of the liner. Each assembly is similarly mounted in a corresponding receptacle with fluid seals interposed between the openings where the fluid enters and the lower portion of the receptacle or fitting closely in these regions. As fluid flows along each core assembly a pressure drop is produced along the fluid so that the fluid which emerges from each core assembly is at a lower pressure than the fluid which enters the core assembly. However because of the seals interposed in the mountings of the units and assemblies the pressures above and below the units and assemblies are balanced and the units are held in the liners and the assemblies are held in the receptacles by their weights as they have a higher specific gravity than the fluid. The low-pressure spaces between each module and its liner and between each core assembly and its module is vented to the low-pressure regions of the vessel to assure that fluid which leaks through the seals does not accumulate and destroy the hydraulic balance.

  9. NUCLEAR REACTORS

    DOEpatents

    Long, E.; Ashley, J.W.

    1958-12-16

    A graphite moderator structure is described for a gas-cooled nuclear reactor having a vertical orlentation wherein the structure is physically stable with regard to dlmensional changes due to Wigner growth properties of the graphite, and leakage of coolant gas along spaces in the structure is reduced. The structure is comprised of stacks of unlform right prismatic graphite blocks positioned in layers extending in the direction of the lengths of the blocks, the adjacent end faces of the blocks being separated by pairs of tiles. The blocks and tiles have central bores which are in alignment when assembled and are provided with cooperatlng keys and keyways for physical stability.

  10. ELECTRONUCLEAR REACTOR

    DOEpatents

    Lawrence, E.O.; McMillan, E.M.; Alvarez, L.W.

    1960-04-19

    An electronuclear reactor is described in which a very high-energy particle accelerator is employed with appropriate target structure to produce an artificially produced material in commercial quantities by nuclear transformations. The principal novelty resides in the combination of an accelerator with a target for converting the accelerator beam to copious quantities of low-energy neutrons for absorption in a lattice of fertile material and moderator. The fertile material of the lattice is converted by neutron absorption reactions to an artificially produced material, e.g., plutonium, where depleted uranium is utilized as the fertile material.

  11. REACTOR COMPONETN

    DOEpatents

    Creutz, E.C.

    1959-10-27

    A reactor fuel element comprised of a slug of fissionable material disposed in a sheath of corrosion resistantmaterial is described. The sheath is in the form of a tubular container closed at one end and is in tight-fitting engagement with the peripheral sunface of the slug. An inner cap is insented into the open end of the sheath against the slug, which end is then bent around the inner cap and welded thereto. An outer cap is then welded around its peripheny to the bent portion of the container.

  12. Photocatalytic reactor

    DOEpatents

    Bischoff, B.L.; Fain, D.E.; Stockdale, J.A.D.

    1999-01-19

    A photocatalytic reactor is described for processing selected reactants from a fluid medium comprising at least one permeable photocatalytic membrane having a photocatalytic material. The material forms an area of chemically active sites when illuminated by light at selected wavelengths. When the fluid medium is passed through the illuminated membrane, the reactants are processed at these sites separating the processed fluid from the unprocessed fluid. A light source is provided and a light transmitting means, including an optical fiber, for transmitting light from the light source to the membrane. 4 figs.

  13. Application of a Two-Dimensional Reservoir Water-Quality Model of Beaver Lake, Arkansas, for the Evaluation of Simulated Changes in Input Water Quality, 2001-2003

    USGS Publications Warehouse

    Galloway, Joel M.; Green, W. Reed

    2007-01-01

    Beaver Lake is considered a primary watershed of concern in the State of Arkansas. As such, information is needed to assess water quality, especially nutrient enrichment, nutrient-algal relations, turbidity, and sediment issues within the system. A previously calibrated two-dimensional, laterally averaged model of hydrodynamics and water quality was used for the evaluation of changes in input nutrient and sediment concentrations on the water quality of the reservoir for the period of April 2001 to April 2003. Nitrogen and phosphorus concentrations were increased and decreased and tested independently and simultaneously to examine the nutrient concentrations and algal response in the reservoir. Suspended-solids concentrations were increased and decreased to identify how solids are distributed in the reservoir, which can contribute to decreased water clarity. The Beaver Lake model also was evaluated using a conservative tracer. A conservative tracer was applied at various locations in the reservoir model to observe the fate and transport and how the reservoir might react to the introduction of a conservative substance, or a worst-case spill scenario. In particular, tracer concentrations were evaluated at the locations of the four public water-supply intakes in Beaver Lake. Nutrient concentrations in Beaver Lake increased proportionally with increases in loads from the three main tributaries. An increase of 10 times the calibrated daily input nitrogen and phosphorus in the three main tributaries resulted in daily mean total nitrogen concentrations in the epilimnion that were nearly 4 times greater than the calibration concentrations at site L2 and more than 2 times greater than the calibrated concentrations at site L5. Increases in daily input nitrogen in the three main tributaries independently did not correspond in substantial increases in concentrations of nitrogen in Beaver Lake. The greatest proportional increase in phosphorus occurred in the epilimnion at sites

  14. Geochemistry of groundwater in the Beaver and Camas Creek drainage basins, eastern Idaho

    USGS Publications Warehouse

    Rattray, Gordon W.; Ginsbach, Michael L.

    2014-01-01

    The U.S. Geological Survey (USGS), in cooperation with the U.S. Department of Energy, is studying the fate and transport of waste solutes in the eastern Snake River Plain (ESRP) aquifer at the Idaho National Laboratory (INL) in eastern Idaho. This effort requires an understanding of the natural and anthropogenic geochemistry of groundwater at the INL and of the important physical and chemical processes controlling the geochemistry. In this study, the USGS applied geochemical modeling to investigate the geochemistry of groundwater in the Beaver and Camas Creek drainage basins, which provide groundwater recharge to the ESRP aquifer underlying the northeastern part of the INL. Data used in this study include petrology and mineralogy from 2 sediment and 3 rock samples, and water-quality analyses from 4 surface-water and 18 groundwater samples. The mineralogy of the sediment and rock samples was analyzed with X-ray diffraction, and the mineralogy and petrology of the rock samples were examined in thin sections. The water samples were analyzed for field parameters, major ions, silica, nutrients, dissolved organic carbon, trace elements, tritium, and the stable isotope ratios of hydrogen, oxygen, carbon, sulfur, and nitrogen. Groundwater geochemistry was influenced by reactions with rocks of the geologic terranes—carbonate rocks, rhyolite, basalt, evaporite deposits, and sediment comprised of all of these rocks. Agricultural practices near and south of Dubois and application of road anti-icing liquids on U.S. Interstate Highway 15 were likely sources of nitrate, chloride, calcium, and magnesium to groundwater. Groundwater geochemistry was successfully modeled in the alluvial aquifer in Camas Meadows and the ESRP fractured basalt aquifer using the geochemical modeling code PHREEQC. The primary geochemical processes appear to be precipitation or dissolution of calcite and dissolution of silicate minerals. Dissolution of evaporite minerals, associated with Pleistocene Lake

  15. Geochemistry of Groundwater in the Beaver and Camas Creek Drainage Basins, Idaho

    NASA Astrophysics Data System (ADS)

    Rattray, G.

    2013-12-01

    The U.S. Geological Survey, in cooperation with the U.S. Department of Energy, is studying the fate and transport of waste solutes in the eastern Snake River Plain (ESRP) aquifer at the Idaho National Laboratory (INL) in eastern Idaho. This effort requires an understanding of the natural and anthropogenic geochemistry of groundwater at the INL and of the important physical and chemical processes controlling the geochemistry. In this study, the USGS applied geochemical modeling to investigate the geochemistry of groundwater in the Beaver and Camas Creek drainage basins, which provide groundwater recharge to the ESRP aquifer underlying the northeastern part of the INL. Data used in this study include petrology and mineralogy from two sediment and three rock samples and water-quality analyses from four surface-water and 18 groundwater samples. The mineralogy of the sediment and rock samples was analyzed with X-ray diffraction and the mineralogy and petrology of the rock samples were examined in thin sections. The water samples were analyzed for field parameters, major ions, nutrients, dissolved organic carbon, trace elements, tritium, and the stable isotope ratios of hydrogen, oxygen, carbon, sulfur, and nitrogen. The groundwater geochemistry was influenced by reactions with rocks of the geologic terranes--carbonate rocks, rhyolite, basalt, evaporite deposits, and sediment comprised of all of these rocks. Agricultural practices near and south of Dubois and application of road anti-icing liquids on U.S. Interstate Highway15 were a source of nitrate, chloride, calcium, and magnesium to groundwater. Groundwater geochemistry was successfully modeled in the alluvial aquifer in Camas Meadows and the ESRP aquifer using the geochemical modeling code PHREEQC. The primary geochemical processes appear to be precipitation of calcite and dissolution of silicate minerals. Dissolution of evaporite minerals, associated with Pleistocene Lake Terreton, is an important contributor of

  16. Hybrid adsorptive membrane reactor

    NASA Technical Reports Server (NTRS)

    Tsotsis, Theodore T. (Inventor); Sahimi, Muhammad (Inventor); Fayyaz-Najafi, Babak (Inventor); Harale, Aadesh (Inventor); Park, Byoung-Gi (Inventor); Liu, Paul K. T. (Inventor)

    2011-01-01

    A hybrid adsorbent-membrane reactor in which the chemical reaction, membrane separation, and product adsorption are coupled. Also disclosed are a dual-reactor apparatus and a process using the reactor or the apparatus.

  17. Hybrid adsorptive membrane reactor

    DOEpatents

    Tsotsis, Theodore T [Huntington Beach, CA; Sahimi, Muhammad [Altadena, CA; Fayyaz-Najafi, Babak [Richmond, CA; Harale, Aadesh [Los Angeles, CA; Park, Byoung-Gi [Yeosu, KR; Liu, Paul K. T. [Lafayette Hill, PA

    2011-03-01

    A hybrid adsorbent-membrane reactor in which the chemical reaction, membrane separation, and product adsorption are coupled. Also disclosed are a dual-reactor apparatus and a process using the reactor or the apparatus.

  18. Seasonal differences in the testicular transcriptome profile of free-living European beavers (Castor fiber L.) determined by the RNA-Seq method

    PubMed Central

    Paukszto, Łukasz; Jastrzębski, Jan P.; Czerwińska, Joanna; Chojnowska, Katarzyna; Kamińska, Barbara; Kurzyńska, Aleksandra; Smolińska, Nina; Giżejewski, Zygmunt; Kamiński, Tadeusz

    2017-01-01

    The European beaver (Castor fiber L.) is an important free-living rodent that inhabits Eurasian temperate forests. Beavers are often referred to as ecosystem engineers because they create or change existing habitats, enhance biodiversity and prepare the environment for diverse plant and animal species. Beavers are protected in most European Union countries, but their genomic background remains unknown. In this study, gene expression patterns in beaver testes and the variations in genetic expression in breeding and non-breeding seasons were determined by high-throughput transcriptome sequencing. Paired-end sequencing in the Illumina HiSeq 2000 sequencer produced a total of 373.06 million of high-quality reads. De novo assembly of contigs yielded 130,741 unigenes with an average length of 1,369.3 nt, N50 value of 1,734, and average GC content of 46.51%. A comprehensive analysis of the testicular transcriptome revealed more than 26,000 highly expressed unigenes which exhibited the highest homology with Rattus norvegicus and Ictidomys tridecemlineatus genomes. More than 8,000 highly expressed genes were found to be involved in fundamental biological processes, cellular components or molecular pathways. The study also revealed 42 genes whose regulation differed between breeding and non-breeding seasons. During the non-breeding period, the expression of 37 genes was up-regulated, and the expression of 5 genes was down-regulated relative to the breeding season. The identified genes encode molecules which are involved in signaling transduction, DNA repair, stress responses, inflammatory processes, metabolism and steroidogenesis. Our results pave the way for further research into season-dependent variations in beaver testes. PMID:28678806

  19. Control Means for Reactor

    DOEpatents

    Manley, J. H.

    1961-06-27

    An apparatus for controlling a nuclear reactor includes a tank just below the reactor, tubes extending from the tank into the reactor, and a thermally expansible liquid neutron absorbent material in the tank. The liquid in the tank is exposed to a beam of neutrons from the reactor which heats the liquid causing it to expand into the reactor when the neutron flux in the reactor rises above a predetermincd danger point. Boron triamine may be used for this purpose.

  20. NEUTRONIC REACTOR

    DOEpatents

    Stewart, H.B.

    1958-12-23

    A nuclear reactor of the type speclfically designed for the irradiation of materials is discussed. In this design a central cyllndrical core of moderating material ls surrounded by an active portlon comprlsed of an annular tank contalning fissionable material immersed ln a liquid moderator. The active portion ls ln turn surrounded by a reflector, and a well ls provided in the center of the core to accommodate the materlals to be irradiated. The over-all dimensions of the core ln at least one plane are equal to or greater than twice the effective slowing down length and equal to or less than twlce the effective diffuslon length for neutrons in the core materials.

  1. NEUTRONIC REACTOR

    DOEpatents

    Daniels, F.

    1962-12-18

    A power plant is described comprising a turbine and employing round cylindrical fuel rods formed of BeO and UO/sub 2/ and stacks of hexagonal moderator blocks of BeO provided with passages that loosely receive the fuel rods so that coolant may flow through the passages over the fuels to remove heat. The coolant may be helium or steam and fiows through at least one more heat exchanger for producing vapor from a body of fluid separate from the coolant, which fluid is to drive the turbine for generating electricity. By this arrangement the turbine and directly associated parts are free of particles and radiations emanating from the reactor. (AEC)

  2. NEUTRONIC REACTOR

    DOEpatents

    McGarry, R.J.

    1958-04-22

    Fluid-cooled nuclear reactors of the type that utilize finned uranium fuel elements disposed in coolant channels in a moderater are described. The coolant channels are provided with removable bushings composed of a non- fissionable material. The interior walls of the bushings have a plurality of spaced, longtudinal ribs separated by grooves which receive the fins on the fuel elements. The lands between the grooves are spaced from the fuel elements to form flow passages, and the size of the now passages progressively decreases as the dlstance from the center of the core increases for the purpose of producing a greater cooling effect at the center to maintain a uniform temperature throughout the core.

  3. Nuclear reactor neutron shielding

    DOEpatents

    Speaker, Daniel P; Neeley, Gary W; Inman, James B

    2017-09-12

    A nuclear reactor includes a reactor pressure vessel and a nuclear reactor core comprising fissile material disposed in a lower portion of the reactor pressure vessel. The lower portion of the reactor pressure vessel is disposed in a reactor cavity. An annular neutron stop is located at an elevation above the uppermost elevation of the nuclear reactor core. The annular neutron stop comprises neutron absorbing material filling an annular gap between the reactor pressure vessel and the wall of the reactor cavity. The annular neutron stop may comprise an outer neutron stop ring attached to the wall of the reactor cavity, and an inner neutron stop ring attached to the reactor pressure vessel. An excore instrument guide tube penetrates through the annular neutron stop, and a neutron plug comprising neutron absorbing material is disposed in the tube at the penetration through the neutron stop.

  4. Reactor and method of operation

    DOEpatents

    Wheeler, John A.

    1976-08-10

    A nuclear reactor having a flattened reactor activity curve across the reactor includes fuel extending over a lesser portion of the fuel channels in the central portion of the reactor than in the remainder of the reactor.

  5. Nuclear reactor

    DOEpatents

    Yant, Howard W.; Stinebiser, Karl W.; Anzur, Gregory C.

    1977-01-01

    A nuclear reactor, particularly a liquid-metal breeder reactor, whose upper internals include outlet modules for channeling the liquid-metal coolant from selected areas of the outlet of the core vertically to the outlet plenum. The modules are composed of a highly-refractory, high corrosion-resistant alloy, for example, INCONEL-718. Each module is disposed to confine and channel generally vertically the coolant emitted from a subplurality of core-component assemblies. Each module has a grid with openings, each opening disposed to receive the coolant from an assembly of the subplurality. The grid in addition serves as a holdown for the assemblies of the corresponding subplurality preventing their excessive ejection upwardly from the core. In the region directly over the core the outlet modules are of such peripheral form that they nest forming a continuum over the core-component assemblies whose outlet coolant they confine. Each subassembly includes a chimney which confines the coolant emitted by its corresponding subassemblies to generally vertical flow between the outlet of the core and the outlet plenum. Each subplurality of assemblies whose emitted coolant is confined by an outlet module includes assemblies which emit lower-temperature coolant, for example, a control-rod assembly, or fertile assemblies, and assemblies which emit coolant of substantially higher temperature, for example, fuel-rod assemblies. The coolants of different temperatures are mixed in the chimneys reducing the effect of stripping (hot-cold temperature fluctuations) on the remainder of the upper internals which are composed typically of AISI-304 or AISI-316 stainless steel.

  6. A SIMULINK environment for flight dynamics and control analysis: Application to the DHC-2 Beaver. Part 1: Implementation of a model library in SIMULINK. Part 2: Nonlinear analysis of the Beaver autopilot

    NASA Technical Reports Server (NTRS)

    Rauw, Marc O.

    1993-01-01

    The design of advanced Automatic Aircraft Control Systems (AACS's) can be improved upon considerably if the designer can access all models and tools required for control system design and analysis through a graphical user interface, from within one software environment. This MSc-thesis presents the first step in the development of such an environment, which is currently being done at the Section for Stability and Control of Delft University of Technology, Faculty of Aerospace Engineering. The environment is implemented within the commercially available software package MATLAB/SIMULINK. The report consists of two parts. Part 1 gives a detailed description of the AACS design environment. The heart of this environment is formed by the SIMULINK implementation of a nonlinear aircraft model in block-diagram format. The model has been worked out for the old laboratory aircraft of the Faculty, the DeHavilland DHC-2 'Beaver', but due to its modular structure, it can easily be adapted for other aircraft. Part 1 also describes MATLAB programs which can be applied for finding steady-state trimmed-flight conditions and for linearization of the aircraft model, and it shows how the built-in simulation routines of SIMULINK have been used for open-loop analysis of the aircraft dynamics. Apart from the implementation of the models and tools, a thorough treatment of the theoretical backgrounds is presented. Part 2 of this report presents a part of an autopilot design process for the 'Beaver' aircraft, which clearly demonstrates the power and flexibility of the AACS design environment from part 1. Evaluations of all longitudinal and lateral control laws by means of nonlinear simulations are treated in detail. A floppy disk containing all relevant MATLAB programs and SIMULINK models is provided as a supplement.

  7. A SIMULINK environment for flight dynamics and control analysis: Application to the DHC-2 Beaver. Part 1: Implementation of a model library in SIMULINK. Part 2: Nonlinear analysis of the Beaver autopilot

    NASA Technical Reports Server (NTRS)

    Rauw, Marc O.

    1993-01-01

    The design of advanced Automatic Aircraft Control Systems (AACS's) can be improved upon considerably if the designer can access all models and tools required for control system design and analysis through a graphical user interface, from within one software environment. This MSc-thesis presents the first step in the development of such an environment, which is currently being done at the Section for Stability and Control of Delft University of Technology, Faculty of Aerospace Engineering. The environment is implemented within the commercially available software package MATLAB/SIMULINK. The report consists of two parts. Part 1 gives a detailed description of the AACS design environment. The heart of this environment is formed by the SIMULINK implementation of a nonlinear aircraft model in block-diagram format. The model has been worked out for the old laboratory aircraft of the Faculty, the DeHavilland DHC-2 'Beaver', but due to its modular structure, it can easily be adapted for other aircraft. Part 1 also describes MATLAB programs which can be applied for finding steady-state trimmed-flight conditions and for linearization of the aircraft model, and it shows how the built-in simulation routines of SIMULINK have been used for open-loop analysis of the aircraft dynamics. Apart from the implementation of the models and tools, a thorough treatment of the theoretical backgrounds is presented. Part 2 of this report presents a part of an autopilot design process for the 'Beaver' aircraft, which clearly demonstrates the power and flexibility of the AACS design environment from part 1. Evaluations of all longitudinal and lateral control laws by means of nonlinear simulations are treated in detail. A floppy disk containing all relevant MATLAB programs and SIMULINK models is provided as a supplement.

  8. Methane fluxes in wetland and forest soils, beaver ponds, and low-order streams of a temperate forest ecosystem

    NASA Astrophysics Data System (ADS)

    Yavitt, J. B.; Lang, G. E.; Sexstone, A. J.

    1990-12-01

    This study was conducted to determine whether temperate wetlands and forests play important roles in the global balances of atmospheric methane. Flux measurements for methane in several different wetland, forest, and open-water (e.g., beaver pond and low-order stream) sites were determined using collection chambers placed over the soil- or water-air interface. All of the sites were located in the Appalachian Mountain region of West Virginia and western Maryland. Between June 1987 and April 1989 the wetland sites acted as small sources of atmospheric methane, with emission rates for methane usually lower than 200 mg CH4/sq m per day; consumption of atmospheric methane in the wetland soils was observed frequently.

  9. Effects of nonlinear model response on allocation of streamflow depletion: exemplified by the case of Beaver Creek, USA

    NASA Astrophysics Data System (ADS)

    Ahlfeld, David P.; Schneider, James C.; Spalding, Charles P.

    2016-11-01

    Anomalies found when apportioning responsibility for streamflow depletion are examined. The anomalies arise when responsibility is assigned to the two states that contribute to depletion of Beaver Creek in the Republican River Basin in the United States. The apportioning procedure for this basin presumes that the sum of streamflow depletions, computed by comparing simulation model runs with and without groundwater pumping from individual states, approximates the streamflow depletion when both states are pumping. In the case study presented here, this presumed superposition fails dramatically. The stream drying and aquifer-storage depletion, as represented in the simulation model used for allocation, are examined in detail to understand the hydrologic and numerical basis for the severe nonlinear response. Users of apportioning procedures that rely on superposition should be aware of the presence and likely magnitude of nonlinear responses in modeling tools.

  10. Methane fluxes in wetland and forest soils, beaver ponds, and low-order streams of a temperate forest ecosystem

    NASA Technical Reports Server (NTRS)

    Yavitt, J. B.; Lang, G. E.; Sexstone, A. J.

    1990-01-01

    This study was conducted to determine whether temperate wetlands and forests play important roles in the global balances of atmospheric methane. Flux measurements for methane in several different wetland, forest, and open-water (e.g., beaver pond and low-order stream) sites were determined using collection chambers placed over the soil- or water-air interface. All of the sites were located in the Appalachian Mountain region of West Virginia and western Maryland. Between June 1987 and April 1989 the wetland sites acted as small sources of atmospheric methane, with emission rates for methane usually lower than 200 mg CH4/sq m per day; consumption of atmospheric methane in the wetland soils was observed frequently.

  11. Methane fluxes in wetland and forest soils, beaver ponds, and low-order streams of a temperate forest ecosystem

    NASA Technical Reports Server (NTRS)

    Yavitt, J. B.; Lang, G. E.; Sexstone, A. J.

    1990-01-01

    This study was conducted to determine whether temperate wetlands and forests play important roles in the global balances of atmospheric methane. Flux measurements for methane in several different wetland, forest, and open-water (e.g., beaver pond and low-order stream) sites were determined using collection chambers placed over the soil- or water-air interface. All of the sites were located in the Appalachian Mountain region of West Virginia and western Maryland. Between June 1987 and April 1989 the wetland sites acted as small sources of atmospheric methane, with emission rates for methane usually lower than 200 mg CH4/sq m per day; consumption of atmospheric methane in the wetland soils was observed frequently.

  12. Reactor safety method

    DOEpatents

    Vachon, Lawrence J.

    1980-03-11

    This invention relates to safety means for preventing a gas cooled nuclear reactor from attaining criticality prior to start up in the event the reactor core is immersed in hydrogenous liquid. This is accomplished by coating the inside surface of the reactor coolant channels with a neutral absorbing material that will vaporize at the reactor's operating temperature.

  13. Retinal thickness measured by spectral-domain optical coherence tomography in eyes without retinal abnormalities: the Beaver Dam Eye Study.

    PubMed

    Myers, Chelsea E; Klein, Barbara E K; Meuer, Stacy M; Swift, Maria K; Chandler, Charles S; Huang, Yijun; Gangaputra, Sapna; Pak, Jeong W; Danis, Ronald P; Klein, Ronald

    2015-03-01

    To examine relationships of age, sex, and systemic and ocular conditions with retinal thickness measured by spectral-domain ocular coherence tomography (SD OCT) in participants without retinal disease. Longitudinal study. setting: Population-based cohort. study population: Persons aged 43-86 years living in Beaver Dam, Wisconsin in 1988-1990. observation procedures: Retinal thickness was measured via SD OCT at the Beaver Dam Eye Study examination in 2008-2010. Retinal disease was determined by ophthalmoscopy, fundus photography, or SD OCT. main outcome measures: Retinal thickness from the inner limiting membrane to the Bruch membrane. The retina was thickest in the inner circle (mean 334.5 μm) and thinnest in the center subfield (285.4 μm). Mean retinal thickness decreased with age in the inner circle (P < .0001) and outer circle (P < .0001). Adjusting for age, eyes in men had thicker retinas than eyes in women in the center subfield (P < .001) and inner circle (P < .001). Sex, axial length/corneal curvature ratio, and peak expiratory flow rate were associated with center subfield thickness. Sex and peak expiratory flow rate were associated with retinal thickness in the inner circle. Alcohol consumption, age, axial length/corneal curvature ratio, cataract surgery, ocular perfusion pressure, and peak expiratory flow rate were associated with retinal thickness in the outer circle. This study provides data for retinal thickness measures in eyes of individuals aged 63 years and older without retinal disease. This information may be useful for clinical trials involving the effects of interventions on retinal thickness and for comparisons with specific retinal diseases affecting the macula. Copyright © 2015 Elsevier Inc. All rights reserved.

  14. Two new species of Eimeria (Apicomplexa: Eimeriidae) from the mountain beaver, Aplodontia rufa (Rodentia: Aplodontiidae), from Oregon.

    PubMed

    McAllister, Chris T; Duszynski, Donald W; McKown, Richard D

    2013-06-01

    Two mountain beavers, Aplodontia rufa , were collected in Lincoln County, Oregon, and examined for coccidia. Both were infected with 2 new species of Eimeria. Oocysts of Eimeria chitkoae n. sp. were ellipsoidal with a bilayered wall and measured (L × W) 24.5 × 20.2 μm, with a shape index (SI) of 1.2. Both micropyle and oocyst residuum were absent, but a polar granule of several fragments was present. Sporocysts were ovoidal, 12.5 × 7.9 μm, SI was 1.6. Stieda and substieda bodies were present, but a parastieda body was absent; a sporocyst residuum was present, composed of a cluster of moderately coarse granules with many scattered fine granules. Stout sporozoites were 14.7 × 2.9 μm in situ, with spheroidal anterior and posterior refractile bodies. Oocysts of Eimeria lewisi n. sp. were ovoidal, with a smooth single-layered wall, and measured 13.7 × 7.8 μm, SI was 1.7. A micropyle and oocyst residuum were absent, but 1-2 polar granule(s) were present. Sporocysts were 6.6 × 4.2 μm, with SI of 1.6. A Stieda body was present, but substieda and parastieda bodies were absent; a sporocyst residuum was present, composed of a small cluster of several granules. Sporozoites were granular, 8.2 × 1.8 μm in situ, with a posterior refractile body. These are the first coccidians reported from the mountain beaver.

  15. Topics on distance correlation, feature screening and lifetime expectancy with application to Beaver Dam eye study data

    NASA Astrophysics Data System (ADS)

    Kong, Jing

    This thesis includes 4 pieces of work. In Chapter 1, we present the work with a method for examining mortality as it is seen to run in families, and lifestyle factors that are also seen to run in families, in a subpopulation of the Beaver Dam Eye Study that has died by 2011. We find significant distance correlations between death ages, lifestyle factors, and family relationships. Considering only sib pairs compared to unrelated persons, distance correlation between siblings and mortality is, not surprisingly, stronger than that between more distantly related family members and mortality. Chapter 2 introduces a feature screening procedure with the use of distance correlation and covariance. We demonstrate a property for distance covariance, which is incorporated in a novel feature screening procedure based on distance correlation as a stopping criterion. The approach is further implemented to two real examples, namely the famous small round blue cell tumors data and the Cancer Genome Atlas ovarian cancer data Chapter 3 pays attention to the right censored human longevity data and the estimation of lifetime expectancy. We propose a general framework of backward multiple imputation for estimating the conditional lifetime expectancy function and the variance of the estimator in the right censoring setting and prove the properties of the estimator. In addition, we apply the method to the Beaver Dam eye study data to study human longevity, where the expected human lifetime are modeled with smoothing spline ANOVA based on the covariates including baseline age, gender, lifestyle factors and disease variables. Chapter 4 compares two imputation methods for right censored data, namely the famous Buckley-James estimator and the backward imputation method proposed in Chapter 3 and shows that backward imputation method is less biased and more robust with heterogeneity.

  16. Analysis of Neogene deformation between Beaver, Utah, and Barstow, California: suggestions for altering the extensional paradigm

    USGS Publications Warehouse

    Anderson, R. Ernest; Beard, L. Sue; Mankinen, Edward A.; Hillhouse, John W.

    2013-01-01

    For more than two decades, the paradigm of large-magnitude (~250 km), northwest-directed (~N70°W) Neogene extensional lengthening between the Colorado Plateau and Sierra Nevada at the approximate latitude of Las Vegas has remained largely unchallenged, as has the notion that the strain integrates with coeval strains in adjacent regions and with plate-boundary strain. The paradigm depends on poorly constrained interconnectedness of extreme-case lengthening estimated at scattered localities within the region. Here we evaluate the soundness of the inferred strain interconnectedness over an area reaching 600 km southwest from Beaver, Utah, to Barstow, California, and conclude that lengthening is overestimated in most areas and, even if the estimates are valid, lengthening is not interconnected in a way that allows for published versions of province-wide summations. We summarize Neogene strike slip in 13 areas distributed from central Utah to Lake Mead. In general, left-sense shear and associated structures define a broad zone of translation approximately parallel to the eastern boundary of the Basin and Range against the Colorado Plateau, a zone we refer to as the Hingeline shear zone. Areas of steep-axis rotation (ranging to 2500 km2) record N-S shortening rather than unevenly distributed lengthening. In most cases, the rotational shortening and extension-parallel folds and thrusts are coupled to, or absorb, strike slip, thus providing valuable insight into how the discontinuous strike-slip faults are simply parts of a broad zone of continuous strain. The discontinuous nature of strike slip and the complex mixture of extensional, contractional, and steep-axis rotational structures in the Hingeline shear zone are similar to those in the Walker Lane belt in the west part of the Basin and Range, and, together, the two record southward displacement of the central and northern Basin and Range relative to the adjacent Colorado Plateau. Understanding this province

  17. Analysis of Neogene deformation between Beaver, Utah and Barstow, California: Suggestions for altering the extensional paradigm

    USGS Publications Warehouse

    Anderson, R. Ernest; Beard, Sue; Mankinen, Edward A.; Hillhouse, John W.

    2013-01-01

    For more than two decades, the paradigm of large-magnitude (~250 km), northwest-directed (~N70°W) Neogene extensional lengthening between the Colorado Plateau and Sierra Nevada at the approximate latitude of Las Vegas has remained largely unchallenged, as has the notion that the strain integrates with coeval strains in adjacent regions and with plate-boundary strain. The paradigm depends on poorly constrained interconnectedness of extreme-case lengthening estimated at scattered localities within the region. Here we evaluate the soundness of the inferred strain interconnectedness over an area reaching 600 km southwest from Beaver, Utah, to Barstow, California, and conclude that lengthening is overestimated in most areas and, even if the estimates are valid, lengthening is not interconnected in a way that allows for published versions of province-wide summations.We summarize Neogene strike slip in 13 areas distributed from central Utah to Lake Mead. In general, left-sense shear and associated structures define a broad zone of translation approximately parallel to the eastern boundary of the Basin and Range against the Colorado Plateau, a zone we refer to as the Hingeline shear zone. Areas of steep-axis rotation (ranging to 2500 km2) record N-S shortening rather than unevenly distributed lengthening. In most cases, the rotational shortening and extension-parallel folds and thrusts are coupled to, or absorb, strike slip, thus providing valuable insight into how the discontinuous strike-slip faults are simply parts of a broad zone of continuous strain. The discontinuous nature of strike slip and the complex mixture of extensional, contractional, and steep-axis rotational structures in the Hingeline shear zone are similar to those in the Walker Lane belt in the west part of the Basin and Range, and, together, the two record southward displacement of the central and northern Basin and Range relative to the adjacent Colorado Plateau. Understanding this province

  18. Self-Reported Hearing Difficulties Among Adults With Normal Audiograms: The Beaver Dam Offspring Study

    PubMed Central

    Tremblay, Kelly L.; Pinto, Alex; Fischer, Mary E.; Klein, Barbara E. K.; Klein, Ronald; Levy, Sarah; Tweed, Ted S.; Cruickshanks, Karen J.

    2016-01-01

    Objective Clinicians encounter patients who report experiencing hearing difficulty (HD) even when audiometric thresholds fall within normal limits. When there is no evidence of audiometric hearing loss, it generates debate over possible biomedical and psychosocial etiologies. It is possible that self-reported HDs relate to variables within and/or outside the scope of audiology. The purpose of this study is to identify how often, on a population basis, people with normal audiometric thresholds self-report HD and to identify factors associated with such HDs. Design This was a cross-sectional investigation of participants in the Beaver Dam Offspring Study. HD was defined as a self-reported HD on a four-item scale despite having pure-tone audiometric thresholds within normal limits (<20 dB HL0.5, 1, 2, 3, 4, 6, 8 kHz bilaterally, at each frequency). Distortion product otoacoustic emissions and word-recognition performance in quiet and with competing messages were also analyzed. In addition to hearing assessments, relevant factors such as sociodemographic and lifestyle factors, environmental exposures, medical history, health-related quality of life, and symptoms of neurological disorders were also examined as possible risk factors. The Center for Epidemiological Studies-Depression was used to probe symptoms associated with depression, and the Medical Outcomes Study Short-Form 36 mental score was used to quantify psychological stress and social and role disability due to emotional problems. The Visual Function Questionnaire-25 and contrast sensitivity test were used to query vision difficulties. Results Of the 2783 participants, 686 participants had normal audiometric thresholds. An additional grouping variable was created based on the available scores of HD (four self-report questions), which reduced the total dataset to n = 682 (age range, 21–67 years). The percentage of individuals with normal audiometric thresholds who self-reported HD was 12.0% (82 of 682). The

  19. Nuclear reactor

    DOEpatents

    Thomson, Wallace B.

    2004-03-16

    A nuclear reactor comprising a cylindrical pressure vessel, an elongated annular core centrally disposed within and spaced from the pressure vessel, and a plurality of ducts disposed longitudinally of the pressure vessel about the periphery thereof, said core comprising an annular active portion, an annular reflector just inside the active portion, and an annular reflector just outside the active a portion, said annular active portion comprising rectangular slab, porous fuel elements radially disposed around the inner reflector and extending the length of the active portion, wedge-shaped, porous moderator elements disposed adjacent one face of each fuel element and extending the length of the fuel element, the fuel and moderator elements being oriented so that the fuel elements face each other and the moderator elements do likewise, adjacent moderator elements being spaced to provide air inlet channels, and adjacent fuel elements being spaced to provide air outlet channels which communicate with the interior of the peripheral ducts, and means for introducing air into the air inlet channels which passes through the porous moderator elements and porous fuel elements to the outlet channel.

  20. Leptin plasma concentrations, leptin gene expression, and protein localization in the hypothalamic-pituitary-gonadal and hypothalamic-pituitary-adrenal axes of the European beaver (Castor fiber).

    PubMed

    Chojnowska, Katarzyna; Czerwinska, Joanna; Kaminski, Tadeusz; Kaminska, Barbara; Kurzynska, Aleksandra; Bogacka, Iwona

    2017-01-01

    The European beaver (Castor fiber) is the largest seasonal free-living rodent in Eurasia. Since the physiology and endocrine system of this species remains unknown, the present study aimed to determine plasma leptin concentrations and the expression of the leptin gene and protein in the hypothalamic-pituitary-gonadal and hypothalamic-pituitary-adrenal (HPG and HPA) axes of beavers during breeding (April), postbreeding (July), and prebreeding (November) seasons. Leptin plasma concentrations did not change in females, whereas in males, leptin plasma concentrations were higher in July than those in April. The presence of leptin mRNA and protein was found in all examined tissues. In females, leptin mRNA expression in the hypothalamus, pituitary, ovaries, and myometrium was markedly higher in July than that in April. In males, leptin mRNA levels varied across the examined tissues of the HPG and HPA. Leptin synthesis increased in the hypothalamus during breeding and postbreeding seasons, but seasonal changes were not observed in the pituitary. In turn, testicular leptin levels were higher during breeding and prebreeding stages. Seasonal differences in the concentrations of leptin mRNA were also observed in the adrenal cortex. In males, leptin mRNA levels were higher in November than those in April or July. In females, leptin synthesis increased in the adrenal cortex during pregnancy relative to other seasons. This is the first ever study to demonstrate seasonal differences in leptin expression in beaver tissues, and our results could suggest that leptin is involved in the regulation of the HPG and HPA axes during various stages of the reproductive cycle in beavers. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. Tokamak reactor studies

    SciTech Connect

    Baker, C.C.

    1981-01-01

    This paper presents an overview of tokamak reactor studies with particular attention to commercial reactor concepts developed within the last three years. Emphasis is placed on DT fueled reactors for electricity production. A brief history of tokamak reactor studies is presented. The STARFIRE, NUWMAK, and HFCTR studies are highlighted. Recent developments that have increased the commercial attractiveness of tokamak reactor designs are discussed. These developments include smaller plant sizes, higher first wall loadings, improved maintenance concepts, steady-state operation, non-divertor particle control, and improved reactor safety features.

  2. Presence of Antibodies to Leptospira spp. in Black-tailed Prairie Dogs ( Cynomys ludovicianus ) and Beavers ( Castor canadensis ) in Northwestern Mexico.

    PubMed

    López-Pérez, Andrés M; Carreón-Arroyo, Gerardo; Atilano, Daniel; Vigueras-Galván, Ana L; Valdez, Carlos; Toyos, Daniel; Mendizabal, Daniel; López-Islas, Jonathan; Suzán, Gerardo

    2017-10-01

    Leptospires are widespread spirochete bacteria that infect mammals, including rodents and humans. We investigated the presence of Leptospira antibodies in two species of rodents from San Pedro River Basin (SPRB) in northwestern Mexico as part of the black-tailed prairie dog ( Cynomys ludovicianus ) monitoring plan and the North American beaver ( Castor canadensis ) reintroduction program. We sampled a total of 26 black-tailed prairie dogs and three beavers during October-November 2015. We detected antibodies against Leptospira spp. by microagglutination test in 12 (46%) prairie dogs and in two (67%) beavers. The antibody titers for seropositive rodents varied from 1:100 to 1:200, but none of the animals showed clinical signs of disease. We found seven Leptospira spp. serogroups (Autumnalis, Australis, Bataviae, Canicola, Celledoni, Grippotyphosa, and Sejroe) circulating in rodent species in SPRB. We did not find any differences between sex and age concerning Leptospira-positive rodents. Our findings suggest the presence of endemic cycles and potential risks of Leptospira infection in both species from SPRB. Although the impact of this infection on threatened species remains unclear, human activities and environmental stress might facilitate the emergence or reemergence of leptospirosis disease as has been reported elsewhere.

  3. Suspended-sediment and turbidity responses to sediment and turbidity reduction projects in the Beaver Kill, Stony Clove Creek, and Warner Creek, Watersheds, New York, 2010–14

    USGS Publications Warehouse

    Siemion, Jason; McHale, Michael R.; Davis, Wae Danyelle

    2016-12-05

    Suspended-sediment concentrations (SSCs) and turbidity were monitored within the Beaver Kill, Stony Clove Creek, and Warner Creek tributaries to the upper Esopus Creek in New York, the main source of water to the Ashokan Reservoir, from October 1, 2010, through September 30, 2014. The purpose of the monitoring was to determine the effects of suspended-sediment and turbidity reduction projects (STRPs) on SSC and turbidity in two of the three streams; no STRPs were constructed in the Beaver Kill watershed. During the study period, four STRPs were completed in the Stony Clove Creek and Warner Creek watersheds. Daily mean SSCs decreased significantly for a given streamflow after the STRPs were completed. The most substantial decreases in daily mean SSCs were measured at the highest streamflows. Background SSCs, as measured in water samples collected in upstream reference stream reaches, in all three streams in this study were less than 5 milligrams per liter during low and high streamflows. Longitudinal stream sampling identified stream reaches with failing hillslopes in contact with the stream channel as the primary sediment sources in the Beaver Kill and Stony Clove Creek watersheds.

  4. Hybrid plasmachemical reactor

    SciTech Connect

    Lelevkin, V. M. Smirnova, Yu. G.; Tokarev, A. V.

    2015-04-15

    A hybrid plasmachemical reactor on the basis of a dielectric barrier discharge in a transformer is developed. The characteristics of the reactor as functions of the dielectric barrier discharge parameters are determined.

  5. Attrition reactor system

    SciTech Connect

    Scott, Charles D.; Davison, Brian H.

    1993-01-01

    A reactor vessel for reacting a solid particulate with a liquid reactant has a centrifugal pump in circulatory flow communication with the reactor vessel for providing particulate attrition, resulting in additional fresh surface where the reaction can occur.

  6. Attrition reactor system

    SciTech Connect

    Scott, C.D.; Davison, B.H.

    1993-09-28

    A reactor vessel for reacting a solid particulate with a liquid reactant has a centrifugal pump in circulatory flow communication with the reactor vessel for providing particulate attrition, resulting in additional fresh surface where the reaction can occur. 2 figures.

  7. Period meter for reactors

    DOEpatents

    Rusch, Gordon K.

    1976-01-06

    An improved log N amplifier type nuclear reactor period meter with reduced probability for noise-induced scrams is provided. With the reactor at low power levels a sampling circuit is provided to determine the reactor period by measuring the finite change in the amplitude of the log N amplifier output signal for a predetermined time period, while at high power levels, differentiation of the log N amplifier output signal provides an additional measure of the reactor period.

  8. NEUTRONIC REACTOR POWER PLANT

    DOEpatents

    Metcalf, H.E.

    1962-12-25

    This patent relates to a nuclear reactor power plant incorporating an air-cooled, beryllium oxide-moderated, pebble bed reactor. According to the invention means are provided for circulating a flow of air through tubes in the reactor to a turbine and for directing a sidestream of the circu1ating air through the pebble bed to remove fission products therefrom as well as assist in cooling the reactor. (AEC)

  9. NUCLEAR REACTOR CONTROL SYSTEM

    DOEpatents

    Epler, E.P.; Hanauer, S.H.; Oakes, L.C.

    1959-11-01

    A control system is described for a nuclear reactor using enriched uranium fuel of the type of the swimming pool and other heterogeneous nuclear reactors. Circuits are included for automatically removing and inserting the control rods during the course of normal operation. Appropriate safety circuits close down the nuclear reactor in the event of emergency.

  10. Improved vortex reactor system

    DOEpatents

    Diebold, James P.; Scahill, John W.

    1995-01-01

    An improved vortex reactor system for affecting fast pyrolysis of biomass and Refuse Derived Fuel (RDF) feed materials comprising: a vortex reactor having its axis vertically disposed in relation to a jet of a horizontally disposed steam ejector that impels feed materials from a feeder and solids from a recycle loop along with a motive gas into a top part of said reactor.

  11. Advanced Test Reactor Tour

    SciTech Connect

    Miley, Don

    2011-01-01

    The Advanced Test Reactor at Idaho National Laboratory is the foremost nuclear materials test reactor in the world. This virtual tour describes the reactor, how experiments are conducted, and how spent nuclear fuel is handled and stored. For more information about INL research, visit http://www.facebook.com/idahonationallaboratory.

  12. Advanced Test Reactor Tour

    ScienceCinema

    Miley, Don

    2016-07-12

    The Advanced Test Reactor at Idaho National Laboratory is the foremost nuclear materials test reactor in the world. This virtual tour describes the reactor, how experiments are conducted, and how spent nuclear fuel is handled and stored. For more information about INL research, visit http://www.facebook.com/idahonationallaboratory.

  13. NEUTRONIC REACTOR SHIELDING

    DOEpatents

    Borst, L.B.

    1961-07-11

    A special hydrogenous concrete shielding for reactors is described. In addition to Portland cement and water, the concrete essentially comprises 30 to 60% by weight barytes aggregate for enhanced attenuation of fast neutrons. The biological shields of AEC's Oak Ridge Graphite Reactor and Materials Testing Reactor are particular embodiments.

  14. High solids fermentation reactor

    DOEpatents

    Wyman, Charles E.; Grohmann, Karel; Himmel, Michael E.; Richard, Christopher J.

    1993-01-01

    A fermentation reactor and method for fermentation of materials having greater than about 10% solids. The reactor includes a rotatable shaft along the central axis, the shaft including rods extending outwardly to mix the materials. The reactor and method are useful for anaerobic digestion of municipal solid wastes to produce methane, for production of commodity chemicals from organic materials, and for microbial fermentation processes.

  15. High solids fermentation reactor

    DOEpatents

    Wyman, Charles E.; Grohmann, Karel; Himmel, Michael E.; Richard, Christopher J.

    1993-03-02

    A fermentation reactor and method for fermentation of materials having greater than about 10% solids. The reactor includes a rotatable shaft along the central axis, the shaft including rods extending outwardly to mix the materials. The reactor and method are useful for anaerobic digestion of municipal solid wastes to produce methane, for production of commodity chemicals from organic materials, and for microbial fermentation processes.

  16. Efficient Silicon Reactor

    NASA Technical Reports Server (NTRS)

    Bates, H. E.; Hill, D. M.; Jewett, D. N.

    1983-01-01

    High-purity silicon efficiently produced and transferred by continuous two-cycle reactor. New reactor operates in relatively-narrow temperature rate and uses large surfaces area to minimize heat expenditure and processing time in producing silicon by hydrogen reduction of trichlorosilane. Two cycles of reactor consists of silicon production and removal.

  17. Reactor vessel support system

    DOEpatents

    Golden, Martin P.; Holley, John C.

    1982-01-01

    A reactor vessel support system includes a support ring at the reactor top supported through a box ring on a ledge of the reactor containment. The box ring includes an annular space in the center of its cross-section to reduce heat flow and is keyed to the support ledge to transmit seismic forces from the reactor vessel to the containment structure. A coolant channel is provided at the outside circumference of the support ring to supply coolant gas through the keyways to channels between the reactor vessel and support ledge into the containment space.

  18. Nuclear reactor overflow line

    DOEpatents

    Severson, Wayne J.

    1976-01-01

    The overflow line for the reactor vessel of a liquid-metal-cooled nuclear reactor includes means for establishing and maintaining a continuous bleed flow of coolant amounting to 5 to 10% of the total coolant flow through the overflow line to prevent thermal shock to the overflow line when the reactor is restarted following a trip. Preferably a tube is disposed concentrically just inside the overflow line extending from a point just inside the reactor vessel to an overflow tank and a suction line is provided opening into the body of liquid metal in the reactor vessel and into the annulus between the overflow line and the inner tube.

  19. Thorium fueled reactor

    NASA Astrophysics Data System (ADS)

    Sipaun, S.

    2017-01-01

    Current development in thorium fueled reactors shows that they can be designed to operate in the fast or thermal spectrum. The thorium/uranium fuel cycle converts fertile thorium-232 into fissile uranium-233, which fissions and releases energy. This paper analyses the characteristics of thorium fueled reactors and discusses the thermal reactor option. It is found that thorium fuel can be utilized in molten salt reactors through many configurations and designs. A balanced assessment on the feasibility of adopting one reactor technology versus another could lead to optimized benefits of having thorium resource.

  20. Extreme clonal uniformity of Phoxinus eos/neogaeus gynogens (pisces: Cyprinidae) among variable habitats in northern Minnesota beaver ponds.

    PubMed Central

    Elder, J F; Schlosser, I J

    1995-01-01

    Genetic surveys of parthenogenetic vertebrate populations have demonstrated a common pattern of relatively high degrees of clonal variation and the coexistence of numerous clones. In striking contrast, the Phoxinus eos/Phoxinus neogaeus/hybrid gynogen complex of cyprinid fishes exhibits no clonal variation within a northern Minnesota drainage characterized by successional beaver ponds. Gynogens were sampled from three habitats in each of four different pond types in a single drainage in Voyageurs National Park, Minnesota. The abundance of gynogens relative to sexual dace varied with pond type, being least common in deep upland ponds and most common in shallow, collapsed, lowland ponds (13.4% and 48.6%, respectively). Simple-sequence multilocus DNA fingerprinting of 464 individual gynogens detected one, and only one, clone. DNA fingerprints, generated sequentially by using three oligonucleotide probes, (CAC)5, (GACA)4, and the Jeffreys' 33.15 probe, all revealed the same unprecedented lack of variation. The extreme lack of clonal diversity in these gynogens across a range of habitat types does not fit the general pattern of high clonal diversity found within populations of other vertebrate parthenogens. Images Fig. 1 Fig. 2 PMID:7761438

  1. Identification of Novel Genetic Loci for Intraocular Pressure: A Genomewide Scan of the Beaver Dam Eye Study

    PubMed Central

    Duggal, Priya; Klein, Alison P.; Lee, Kristine E.; Klein, Ronald; Klein, Barbara E. K.; Bailey-Wilson, Joan E.

    2008-01-01

    Clinical Relevance Glaucoma is a leading cause of blindness in the world, and the identification of genes that contribute to this disease is essential. Elevated intraocular pressure (IOP) is a principal risk factor for primary open-angle glaucoma (POAG), and an intriguing quantitative trait that may strongly influence the development of disease. Objectives The objective of this study was to identify genetic loci that control IOP. Methods We performed a genomewide scan of IOP, using 486 pedigrees ascertained through a population based cohort, the Beaver Dam Eye Study. Linkage analysis was performed using the modified Haseman-Elston regression models and variance components linkage analysis. Results Seven regions of interest were identified on chromosomes 2, 5, 6, 7, 12, 15 and 19. The novel linkage region on chromosome 19p had an empirical multipoint pvalue of 6.1×10−5. Two of the regions (2 and 19) are especially interesting since each has been identified as potential linkage regions for blood pressure. Conclusions The results of this genomewide scan provide evidence that a quantitative trait locus (QTL) may influence elevated IOP and may co-localize with blood pressure loci. These loci may control systemic pressure reflected in the eye and vascular system. PMID:17210855

  2. Health-hazard evaluation report HETA 88-274-1924, Office of Employment Security, Beaver Falls, Pennsylvania

    SciTech Connect

    Roper, P.; Savery, H.

    1988-09-01

    In response to a request from the Pennsylvania Social Services Union, an evaluation was made of possible hazardous working conditions at the Office of Employment Security, located in Beaver Falls, Pennsylvania. Employees had complained of dizziness; coughing; burning of the eyes, nose and throat; recurring respiratory infections; and other symptoms. The 30 employees handled unemployment benefits claims and operated a job placement service. Potential sources of air contaminants in the building included a dry toner type photocopier, fiberglass insulation inside the air supply ductwork, tobacco smoking, cleaning compounds, office furnishings and supplies, and building construction materials. No carbon-monoxide or nitrogen-dioxide levels were detected. No evidence was found to support any causal relationship between work related experiences and the symptoms expressed by the workers. The authors recommend that specific actions be taken to ensure the HVAC system is operating optimally, that parking of vehicles in the alley where the air intakes are located is prevented, and that certain ergonomic recommendations for operators of video-display units are adopted to lessen their muscle fatigue and general discomfort.

  3. High temperature reactors

    NASA Astrophysics Data System (ADS)

    Dulera, I. V.; Sinha, R. K.

    2008-12-01

    With the advent of high temperature reactors, nuclear energy, in addition to producing electricity, has shown enormous potential for the production of alternate transport energy carrier such as hydrogen. High efficiency hydrogen production processes need process heat at temperatures around 1173-1223 K. Bhabha Atomic Research Centre (BARC), is currently developing concepts of high temperature reactors capable of supplying process heat around 1273 K. These reactors would provide energy to facilitate combined production of hydrogen, electricity, and drinking water. Compact high temperature reactor is being developed as a technology demonstrator for associated technologies. Design has been also initiated for a 600 MWth innovative high temperature reactor. High temperature reactor development programme has opened new avenues for research in areas like advanced nuclear fuels, high temperature and corrosion resistant materials and protective coatings, heavy liquid metal coolant technologies, etc. The paper highlights design of these reactors and their material related requirements.

  4. Spinning fluids reactor

    DOEpatents

    Miller, Jan D; Hupka, Jan; Aranowski, Robert

    2012-11-20

    A spinning fluids reactor, includes a reactor body (24) having a circular cross-section and a fluid contactor screen (26) within the reactor body (24). The fluid contactor screen (26) having a plurality of apertures and a circular cross-section concentric with the reactor body (24) for a length thus forming an inner volume (28) bound by the fluid contactor screen (26) and an outer volume (30) bound by the reactor body (24) and the fluid contactor screen (26). A primary inlet (20) can be operatively connected to the reactor body (24) and can be configured to produce flow-through first spinning flow of a first fluid within the inner volume (28). A secondary inlet (22) can similarly be operatively connected to the reactor body (24) and can be configured to produce a second flow of a second fluid within the outer volume (30) which is optionally spinning.

  5. Reactor water cleanup system

    DOEpatents

    Gluntz, Douglas M.; Taft, William E.

    1994-01-01

    A reactor water cleanup system includes a reactor pressure vessel containing a reactor core submerged in reactor water. First and second parallel cleanup trains are provided for extracting portions of the reactor water from the pressure vessel, cleaning the extracted water, and returning the cleaned water to the pressure vessel. Each of the cleanup trains includes a heat exchanger for cooling the reactor water, and a cleaner for cleaning the cooled reactor water. A return line is disposed between the cleaner and the pressure vessel for channeling the cleaned water thereto in a first mode of operation. A portion of the cooled water is bypassed around the cleaner during a second mode of operation and returned through the pressure vessel for shutdown cooling.

  6. Reactor water cleanup system

    DOEpatents

    Gluntz, D.M.; Taft, W.E.

    1994-12-20

    A reactor water cleanup system includes a reactor pressure vessel containing a reactor core submerged in reactor water. First and second parallel cleanup trains are provided for extracting portions of the reactor water from the pressure vessel, cleaning the extracted water, and returning the cleaned water to the pressure vessel. Each of the cleanup trains includes a heat exchanger for cooling the reactor water, and a cleaner for cleaning the cooled reactor water. A return line is disposed between the cleaner and the pressure vessel for channeling the cleaned water thereto in a first mode of operation. A portion of the cooled water is bypassed around the cleaner during a second mode of operation and returned through the pressure vessel for shutdown cooling. 1 figure.

  7. Neutron fluxes in test reactors

    SciTech Connect

    Youinou, Gilles Jean-Michel

    2017-01-01

    Communicate the fact that high-power water-cooled test reactors such as the Advanced Test Reactor (ATR), the High Flux Isotope Reactor (HFIR) or the Jules Horowitz Reactor (JHR) cannot provide fast flux levels as high as sodium-cooled fast test reactors. The memo first presents some basics physics considerations about neutron fluxes in test reactors and then uses ATR, HFIR and JHR as an illustration of the performance of modern high-power water-cooled test reactors.

  8. HORIZONTAL BOILING REACTOR SYSTEM

    DOEpatents

    Treshow, M.

    1958-11-18

    Reactors of the boiling water type are described wherein water serves both as the moderator and coolant. The reactor system consists essentially of a horizontal pressure vessel divided into two compartments by a weir, a thermal neutronic reactor core having vertical coolant passages and designed to use water as a moderator-coolant posltioned in one compartment, means for removing live steam from the other compartment and means for conveying feed-water and water from the steam compartment to the reactor compartment. The system further includes auxiliary apparatus to utilize the steam for driving a turbine and returning the condensate to the feed-water inlet of the reactor. The entire system is designed so that the reactor is self-regulating and has self-limiting power and self-limiting pressure features.

  9. High energy reactor neutrinos

    NASA Astrophysics Data System (ADS)

    Raper, Neill

    We present the first measurement of a nonzero reactor neutrino flux with energies above 8 MeV. Measurements are taken with the Daya Bay Reactor Neutrino Experiments detectors, using the Guangdong Nuclear Power Station as a source. Disagreement between data and theory regarding rate and shape of reactor neutrino spectra have made the need for direct measurement clear. Data are especially useful at high energies, where far fewer isotopes contribute. Neutrino candidates are correlated to reactor power and reactor power is extrapolated to zero in order to separate neutrino events from background. We find evidence of reactor neutrinos up to ˜12.5 MeV at 1.92 sigma above 0 and include a survey of isotopes likely to be contributing neutrinos in this energy range.

  10. Hybrid reactors. [Fuel cycle

    SciTech Connect

    Moir, R.W.

    1980-09-09

    The rationale for hybrid fusion-fission reactors is the production of fissile fuel for fission reactors. A new class of reactor, the fission-suppressed hybrid promises unusually good safety features as well as the ability to support 25 light-water reactors of the same nuclear power rating, or even more high-conversion-ratio reactors such as the heavy-water type. One 4000-MW nuclear hybrid can produce 7200 kg of /sup 233/U per year. To obtain good economics, injector efficiency times plasma gain (eta/sub i/Q) should be greater than 2, the wall load should be greater than 1 MW.m/sup -2/, and the hybrid should cost less than 6 times the cost of a light-water reactor. Introduction rates for the fission-suppressed hybrid are usually rapid.

  11. Effects of reintroduced beaver (Castor canadensis) on riparian bird community structure along the upper San Pedro River, southeastern Arizona and northern Sonora, Mexico

    USGS Publications Warehouse

    Johnson, Glenn E.; van Riper, Charles

    2014-01-01

    Chapter 1.—We measured bird abundance and richness along the upper San Pedro River in 2005 and 2006, in order to document how beavers (Castor canadensis) may act as ecosystem engineers after their reintroduction to a desert riparian area in the Southwestern United States. In areas where beavers colonized, we found higher bird abundance and richness of bird groups, such as all breeding birds, insectivorous birds, and riparian specialists, and higher relative abundance of many individual species—including several avian species of conservation concern. Chapter 2.—We conducted bird surveys in riparian areas along the upper San Pedro River in southeastern Arizona (United States) and northern Sonora (Mexico) in order to describe factors influencing bird community dynamics and the distribution and abundance of species, particularly those of conservation concern. These surveys were also used to document the effects of the ecosystem-altering activities of a recently reintroduced beavers (Castor canadensis). Chapter 3.—We reviewed Southwestern Willow Flycatcher (Empidonax traillii extimus) nest records and investigated the potential for future breeding along the upper San Pedro River in southeastern Arizona, where in July 2005 we encountered the southernmost verifiable nest attempt for the species. Continued conservation and management of the area’s riparian vegetation and surface water has potential to contribute additional breeding sites for this endangered Willow Flycatcher subspecies. Given the nest record along the upper San Pedro River and the presence of high-density breeding sites to the north, the native cottonwood-willow forests of the upper San Pedro River could become increasingly important to E. t. extimus recovery, especially considering the anticipated effect of the tamarisk leaf beetle (Diorhabda carinulata) on riparian habitat north of the region.

  12. Improved vortex reactor system

    DOEpatents

    Diebold, J.P.; Scahill, J.W.

    1995-05-09

    An improved vortex reactor system is described for affecting fast pyrolysis of biomass and Refuse Derived Fuel (RDF) feed materials comprising: a vortex reactor having its axis vertically disposed in relation to a jet of a horizontally disposed steam ejector that impels feed materials from a feeder and solids from a recycle loop along with a motive gas into a top part of said reactor. 12 figs.

  13. The Integral Fast Reactor

    SciTech Connect

    Chang, Y.I.

    1988-01-01

    The Integral Fast Reactor (IFR) is an innovative liquid metal reactor concept being developed at Argonne National Laboratory. It seeks to specifically exploit the inherent properties of liquid metal cooling and metallic fuel in a way that leads to substantial improvements in the characteristics of the complete reactor system. This paper describes the key features and potential advantages of the IFR concept, with emphasis on its safety characteristics. 3 refs., 4 figs., 1 tab.

  14. NEUTRONIC REACTOR CONTROL

    DOEpatents

    Dreffin, R.S.

    1959-12-15

    A control means for a nuclear reactor is described. Particularly a device extending into the active portion of the reactor consisting of two hollow elements coaxially disposed and forming a channel therebetween, the cross sectional area of the channel increasing from each extremity of the device towards the center thereof. An element of neutron absorbing material is slidably positionable within the inner hollow element and a fluid reactor poison is introduced into the channel defined by the two hollow elements.

  15. NEUTRONIC REACTOR SYSTEM

    DOEpatents

    Goett, J.J.

    1961-01-24

    A system is described which includes a neutronic reactor containing a dispersion of fissionable material in a liquid moderator as fuel and a conveyor to which a portion of the dispersion may be passed and wherein the self heat of the slurry evaporates the moderator. Means are provided for condensing the liquid moderator and returning it to the reactor and for conveying the dried fissionable material away from the reactor.

  16. FLOW SYSTEM FOR REACTOR

    DOEpatents

    Zinn, W.H.

    1963-06-11

    A reactor is designed with means for terminating the reaction when returning coolant is below a predetermined temperature. Coolant flowing from the reactor passes through a heat exchanger to a lower reservoir, and then circulates between the lower reservoir and an upper reservoir before being returned to the reactor. Means responsive to the temperature of the coolant in the return conduit terminate the chain reaction when the temperature reaches a predetermined minimum value. (AEC)

  17. University Reactor Sharing Program

    SciTech Connect

    Dr. W.D. Reece

    1999-09-01

    The University Reactor Sharing Program provides funding for reactor experimentation to institutions that do not normally have access to a research reactor. Research projects supported by the program include items such as dating geological material to producing high current super conducting magnets. The funding also gives small colleges and universities the opportunity to use the facility for teaching courses in nuclear processes; specifically neutron activation analysis and gamma spectroscopy.

  18. Long-term rise of the Water Table in the Northeast US: Climate Variability, Land-Use Change, or Angry Beavers?

    NASA Astrophysics Data System (ADS)

    Boutt, D. F.

    2011-12-01

    The scientific evidence that humans are directly influencing the Earth's natural climate is increasingly compelling. Numerous studies suggest that climate change will lead to changes in the seasonality of surface water availability thereby increasing the need for groundwater development to offset those shortages. Research suggests that the Northeast region of the U.S. is experiencing significant changes to its' natural climate and hydrologic systems. Previous analysis of a long-term regional compilation of the water table response to the last 60 years of climate variability in New England documented a wide range of variability. The investigation evaluated the physical mechanisms, natural variability and response of aquifers in New England using 100 long term groundwater monitoring stations with 20 or more years of data coupled with 67 stream gages, 75 precipitation stations, and 43 temperature stations. Groundwater trends were calculated as normalized anomalies and analyzed with respect to regional compiled precipitation, temperature, and streamflow anomalies to understand the sensitivity of the aquifer systems to change. Interestingly, a trend and regression analysis demonstrate that water level fluctuations are producing statistically significant results with increasing water levels over at least the past thirty years at most (80 out of 100) well sites. In this contribution we investigate the causal mechanisms behind the observed ground water level trends using site-by-site land-use change assessments, cluster analysis, and spatial analysis of beaver populations (a possible proxy for beaver activity). Regionally, average annual precipitation has been slightly increasing since 1900, with 95% of the stations having statistically significant positive trends. Despite this, no correlation is observed between the magnitude of the annual precipitation trends and the magnitude of the groundwater level changes. Land-use change throughout the region has primarily taken

  19. Pressurized fluidized bed reactor

    DOEpatents

    Isaksson, Juhani

    1996-01-01

    A pressurized fluid bed reactor power plant includes a fluidized bed reactor contained within a pressure vessel with a pressurized gas volume between the reactor and the vessel. A first conduit supplies primary gas from the gas volume to the reactor, passing outside the pressure vessel and then returning through the pressure vessel to the reactor, and pressurized gas is supplied from a compressor through a second conduit to the gas volume. A third conduit, comprising a hot gas discharge, carries gases from the reactor, through a filter, and ultimately to a turbine. During normal operation of the plant, pressurized gas is withdrawn from the gas volume through the first conduit and introduced into the reactor at a substantially continuously controlled rate as the primary gas to the reactor. In response to an operational disturbance of the plant, the flow of gas in the first, second, and third conduits is terminated, and thereafter the pressure in the gas volume and in the reactor is substantially simultaneously reduced by opening pressure relief valves in the first and third conduits, and optionally by passing air directly from the second conduit to the turbine.

  20. Remote Reactor Monitoring

    SciTech Connect

    Bernstein, Adam; Dazeley, Steve; Dobie, Doug; Marleau, Peter; Brennan, Jim; Gerling, Mark; Sumner, Matthew; Sweany, Melinda

    2014-10-21

    The overall goal of the WATCHMAN project is to experimentally demonstrate the potential of water Cerenkov antineutrino detectors as a tool for remote monitoring of nuclear reactors. In particular, the project seeks to field a large prototype gadolinium-doped, water-based antineutrino detector to demonstrate sensitivity to a power reactor at ~10 kilometer standoff using a kiloton scale detector. The technology under development, when fully realized at large scale, could provide remote near-real-time information about reactor existence and operational status for small operating nuclear reactors out to distances of many hundreds of kilometers.

  1. Pressurized fluidized bed reactor

    DOEpatents

    Isaksson, J.

    1996-03-19

    A pressurized fluid bed reactor power plant includes a fluidized bed reactor contained within a pressure vessel with a pressurized gas volume between the reactor and the vessel. A first conduit supplies primary gas from the gas volume to the reactor, passing outside the pressure vessel and then returning through the pressure vessel to the reactor, and pressurized gas is supplied from a compressor through a second conduit to the gas volume. A third conduit, comprising a hot gas discharge, carries gases from the reactor, through a filter, and ultimately to a turbine. During normal operation of the plant, pressurized gas is withdrawn from the gas volume through the first conduit and introduced into the reactor at a substantially continuously controlled rate as the primary gas to the reactor. In response to an operational disturbance of the plant, the flow of gas in the first, second, and third conduits is terminated, and thereafter the pressure in the gas volume and in the reactor is substantially simultaneously reduced by opening pressure relief valves in the first and third conduits, and optionally by passing air directly from the second conduit to the turbine. 1 fig.

  2. HOMOGENEOUS NUCLEAR POWER REACTOR

    DOEpatents

    King, L.D.P.

    1959-09-01

    A homogeneous nuclear power reactor utilizing forced circulation of the liquid fuel is described. The reactor does not require fuel handling outside of the reactor vessel during any normal operation including complete shutdown to room temperature, the reactor being selfregulating under extreme operating conditions and controlled by the thermal expansion of the liquid fuel. The liquid fuel utilized is a uranium, phosphoric acid, and water solution which requires no gus exhaust system or independent gas recombining system, thereby eliminating the handling of radioiytic gas.

  3. Membrane reactors at Degussa.

    PubMed

    Wöltinger, Jens; Karau, Andreas; Leuchtenberger, Wolfgang; Drauz, Karlheinz

    2005-01-01

    The review covers the development of membrane reactor technologies at Degussa for the synthesis of fine chemicals. The operation of fed-batch or continuous biocatalytic processes in the enzyme membrane reactor (EMR) is well established at Degussa. Degussa has experience of running EMRs from laboratory gram scale up to a production scale of several hundreds of tons per year. The transfer of the enzyme membrane reactor from biocatalysis to chemical catalysis in the chemzyme membrane reactor (CMR) is discussed. Various homogeneous catalysts have been investigated in the CMR, and the scope and limitation of this new technique is discussed.

  4. Assessment of conservation easements, total phosphorus, and total suspended solids in West Fork Beaver Creek, Minnesota, 1999-2012

    USGS Publications Warehouse

    Christensen, Victoria G.; Kieta, Kristen A.

    2014-01-01

    This study examined conservation easements and their effectiveness at reducing phosphorus and solids transport to streams. The U.S. Geological Survey cooperated with the Minnesota Board of Water and Soil Resources and worked collaboratively with the Hawk Creek Watershed Project to examine the West Fork Beaver Creek Basin in Renville County, which has the largest number of Reinvest In Minnesota land retirement contracts in the State (as of 2013). Among all conservation easement programs, a total of 24,218 acres of agricultural land were retired throughout Renville County, and 2,718 acres were retired in the West Fork Beaver Creek Basin from 1987 through 2012. Total land retirement increased steadily from 1987 until 2000. In 2000, land retirement increased sharply because of the Minnesota River Conservation Reserve Enhancement Program, then leveled off when the program ended in 2002. Streamflow data were collected during 1999 through 2011, and total phosphorus and total suspended solids data were collected during 1999 through 2012. During this period, the highest peak streamflow of 1,320 cubic feet per second was in March 2010. Total phosphorus and total suspended solids are constituents that tend to increase with increases in streamflow. Annual flow-weighted mean total-phosphorus concentrations ranged from 0.140 to 0.759 milligrams per liter, and annual flow-weighted mean total suspended solids concentrations ranged from 21.3 to 217 milligrams per liter. Annual flow-weighted mean total phosphorus and total suspended solids concentrations decreased steadily during the first 4 years of water-quality sample collection. A downward trend in flow-weighted mean total-phosphorus concentrations was significant from 1999 through 2008; however, flow-weighted total-phosphorus concentrations increased substantially in 2009, and the total phosphorus trend was no longer significant. The high annual flow-weighted mean concentrations for total phosphorus and total suspended solids

  5. Sunlight and the 5-year incidence of early age-related maculopathy: the beaver dam eye study.

    PubMed

    Cruickshanks, K J; Klein, R; Klein, B E; Nondahl, D M

    2001-02-01

    To investigate the relation of sunlight exposure and indicators of sun sensitivity with the 5-year incidence of early age-related maculopathy (ARM). Longitudinal, population-based study. Participants (aged 43-86 years at baseline) in the Beaver Dam Eye Study were reexamined from 1993 to 1995, 5 years after the baseline examination. Questionnaire data about sunlight exposure and sun sensitivity were obtained at baseline. Additional information about earlier life patterns of exposure was ascertained at follow-up. Stereoscopic color fundus photographs were graded to determine the presence of ARM at the 5-year follow-up in eyes free from signs of early ARM at the baseline examination. Leisure time spent outdoors while persons were teenagers (aged 13-19 years) and in their 30s (aged 30-39 years) was significantly associated with the risk of early ARM (odds ratio, 2.09; 95% confidence interval, 1.19-3.65). There was a slight, but nonsignificant, protective effect associated with use of hats and sunglasses while persons were teenagers and in their 30s (odds ratio, 0.72; 95% confidence interval, 0.50-1.03). People with red or blond hair were slightly more likely to develop early ARM than people with darker hair (odds ratio, 1.33; 95% confidence interval, 0.97-1.83). There were no associations between estimated ambient UV-B exposure or markers of sun sensitivity and the incidence of early ARM. Exposure to sunlight may be associated with the development of early ARM.

  6. Stabilization of potential rock slides station 66+00 to station 162+00, US route 51, Beaver County, PA

    SciTech Connect

    Kilburg, J.A.; Perry, D.R.; Posney, K.

    1985-01-01

    Numerous rock slope failures have occurred in major road cuts in Southwestern Pennsylvania over the past several years. Most of these cuts have existed for 25 to 30 years. The obvious hazard to motorists, pedestrians, and the roadway itself has prompted the Pennsylvania Department of Transportation to undertake a comprehensive study of several major cut slopes to determine their stability, both present and long term, and to formulate plans for remedial work where it is considered necessary. A detailed study was completed recently of five large cuts along a two mile stretch of US Route 51 next to the Ohio River in Beaver County, Pennsylvania. The study combined structural geology data and computer models of existing and proposed cut slope configurations. Results of the investigation indicate that the slope will not undergo major failures involving large quantities of rock. Rather, failures will be localized and will involve several cubic yards to several hundred cubic yards of rock. Types of rock failures that occur on this series of road cuts are dominantly plane failures along joint surfaces, with rock falls and joint controlled wedge failures being minor in abundance. Plane failures occur in sandy shale and sandstone beds on joints that are parallel to the Ohio River. The road cuts were made along these joints rather than by well planned rock slope engineering methods. The strike of the joints is parallel to the strike of local fold axes suggesting structural control of the formation of joints. Measures recommended to reduce the potential of rock slides include flattering the slopes, rock bolts, anchored wire mesh, shotcrete, buttresses, and drainage systems.

  7. NEUTRONIC REACTOR SYSTEM

    DOEpatents

    Treshow, M.

    1959-02-10

    A reactor system incorporating a reactor of the heterogeneous boiling water type is described. The reactor is comprised essentially of a core submerged adwater in the lower half of a pressure vessel and two distribution rings connected to a source of water are disposed within the pressure vessel above the reactor core, the lower distribution ring being submerged adjacent to the uppcr end of the reactor core and the other distribution ring being located adjacent to the top of the pressure vessel. A feed-water control valve, responsive to the steam demand of the load, is provided in the feedwater line to the distribution rings and regulates the amount of feed water flowing to each distribution ring, the proportion of water flowing to the submerged distribution ring being proportional to the steam demand of the load. This invention provides an automatic means exterior to the reactor to control the reactivity of the reactor over relatively long periods of time without relying upon movement of control rods or of other moving parts within the reactor structure.

  8. REFLECTOR FOR NEUTRONIC REACTORS

    DOEpatents

    Fraas, A.P.

    1963-08-01

    A reflector for nuclear reactors that comprises an assembly of closely packed graphite rods disposed with their major axes substantially perpendicular to the interface between the reactor core and the reflector is described. Each graphite rod is round in transverse cross section at (at least) its interface end and is provided, at that end, with a coaxial, inwardly tapering hole. (AEC)

  9. NEUTRONIC REACTOR BURIAL ASSEMBLY

    DOEpatents

    Treshow, M.

    1961-05-01

    A burial assembly is shown whereby an entire reactor core may be encased with lead shielding, withdrawn from the reactor site and buried. This is made possible by a five-piece interlocking arrangement that may be easily put together by remote control with no aligning of bolt holes or other such close adjustments being necessary.

  10. N Reactor hydrogen control

    SciTech Connect

    Shuford, D.H.; Kripps, L.J.

    1988-08-01

    Following the accident at the Chernobyl nuclear power reactor in the Soviet Union, a number of reviews were conducted of the N Reactor. Hydrogen generation during postulates severe accidents and the possibility of resulting hydrogen deflagrations/detonations that could affect confinement integrity were issues raised in several reviews, along with recommendations for adding hydrogen mitigation features. To respond to these reviews, an N Reactor Safety Enhancement Program and a subsequent Accelerated Safety Enhancement Program were initiated to address all post-Chernobyl N Reactor review findings. The Safety Enhancement Program and Accelerated Safety Enhancement Program efforts involving hydrogen control included the following: Calculate the potential hydrogen source for a range of severe accidents at the N Reactor to establish an acceptable design basis for the hydrogen mitigation system; Analyze the N Reactor confinement hydrogen mixing capability to identify areas of concern and to the verify effectiveness of the hydrogen mitigation system; Select, design, and construct a hydrogen mitigation system to enhance the N Reactor capability to accommodate possible hydrogen generation from postulated severe accidents; Provide post-accident hydrogen monitoring as an operator aid in assessing confinement conditions. In additions, it was necessary to verify that incorporation of the hydrogen mitigation system had no adverse impact N Reactor safety (e.g., radiological consequence analyses). 77 refs., 25 figs., 10 tabs.

  11. Polymerization Reactor Engineering.

    ERIC Educational Resources Information Center

    Skaates, J. Michael

    1987-01-01

    Describes a polymerization reactor engineering course offered at Michigan Technological University which focuses on the design and operation of industrial polymerization reactors to achieve a desired degree of polymerization and molecular weight distribution. Provides a list of the course topics and assigned readings. (TW)

  12. The Integral Fast Reactor

    SciTech Connect

    Till, C.E.; Chang, Y.I. ); Lineberry, M.J. )

    1990-01-01

    Argonne National Laboratory, since 1984, has been developing the Integral Fast Reactor (IFR). This paper will describe the way in which this new reactor concept came about; the technical, public acceptance, and environmental issues that are addressed by the IFR; the technical progress that has been made; and our expectations for this program in the near term. 5 refs., 3 figs.

  13. Polymerization Reactor Engineering.

    ERIC Educational Resources Information Center

    Skaates, J. Michael

    1987-01-01

    Describes a polymerization reactor engineering course offered at Michigan Technological University which focuses on the design and operation of industrial polymerization reactors to achieve a desired degree of polymerization and molecular weight distribution. Provides a list of the course topics and assigned readings. (TW)

  14. Light water reactor program

    SciTech Connect

    Franks, S.M.

    1994-12-31

    The US Department of Energy`s Light Water Reactor Program is outlined. The scope of the program consists of: design certification of evolutionary plants; design, development, and design certification of simplified passive plants; first-of-a-kind engineering to achieve commercial standardization; plant lifetime improvement; and advanced reactor severe accident program. These program activities of the Office of Nuclear Energy are discussed.

  15. Status of French reactors

    SciTech Connect

    Ballagny, A.

    1997-08-01

    The status of French reactors is reviewed. The ORPHEE and RHF reactors can not be operated with a LEU fuel which would be limited to 4.8 g U/cm{sup 3}. The OSIRIS reactor has already been converted to LEU. It will use U{sub 3}Si{sub 2} as soon as its present stock of UO{sub 2} fuel is used up, at the end of 1994. The decision to close down the SILOE reactor in the near future is not propitious for the start of a conversion process. The REX 2000 reactor, which is expected to be commissioned in 2005, will use LEU (except if the fast neutrons core option is selected). Concerning the end of the HEU fuel cycle, the best option is reprocessing followed by conversion of the reprocessed uranium to LEU.

  16. REACTOR FUEL SCAVENGING MEANS

    DOEpatents

    Coffinberry, A.S.

    1962-04-10

    A process for removing fission products from reactor liquid fuel without interfering with the reactor's normal operation or causing a significant change in its fuel composition is described. The process consists of mixing a liquid scavenger alloy composed of about 44 at.% plutoniunm, 33 at.% lanthanum, and 23 at.% nickel or cobalt with a plutonium alloy reactor fuel containing about 3 at.% lanthanum; removing a portion of the fuel and scavenger alloy from the reactor core and replacing it with an equal amount of the fresh scavenger alloy; transferring the portion to a quiescent zone where the scavenger and the plutonium fuel form two distinct liquid layers with the fission products being dissolved in the lanthanum-rich scavenger layer; and the clean plutonium-rich fuel layer being returned to the reactor core. (AEC)

  17. Reactor Operations Management Plan

    SciTech Connect

    Rice, P.D.

    1991-12-05

    The K-Reactor last operated in April 1988. At that time, K-Reactor was one of three operating reactors at the Savannah River Site (SRS). Following an incident in P-Reactor in August 1988, it was decided to discontinue SRS reactor operation and conduct an extensive program to upgrade operating practices and plant hardware prior to restart of any of the reactors. The K-reactor was the first of three reactors scheduled to resume production. At the present time, it is the only reactor with planned restart. WSRC assumed management of SRS on April 1, 1989. WSRC established the Safety Basis for Restart and a listing of the actions planned to satisfy the Safety Basis. In consultation with DOE, it was determined that proper management of the restart activities would require a single plan that integrated the numerous activities. The plan was entitled the Reactor Operations Management Plan and is referred to simply as the ROMP. The initial version of ROMP was produced in July of 1989. Subsequent modifications led to Revision 3 which was approved by DOE in May, 1990. Other changes were made in a formal change process, resulting in the latest version, Revision 5, being issued in October, 1990. The ROMP contains three key parts: first, the Restart Safety Basis; second, a description of the process for addressing new technical issues and a listing of the established workscope and the associated acceptance criteria; and three, a schedule for executing the work. I will discuss the first two areas, along with the closure process used to assure the intent of ROMP was met. The ROMP activities are all complete and I will not discuss schedule further.

  18. Comparative morphological study on the stereo-structure of the lingual papillae and their connective tissue cores of the American beaver (Castor canadensis).

    PubMed

    Shindo, Junji; Yoshimura, Ken; Kobayashi, Kan

    2006-02-01

    The lingual papillae and the connective tissue cores (CTC) of the American beaver were examined by light and scanning electron microscopy. The tongue of American beaver was about 9 cm in length, 3.5 cm in width, and has a lingual prominence. Four types of papillae (filiform, fungiform, vallate and foliate papillae) were observed. The filiform papillae can be classified into three types (filiform, large filiform and dorm-like papillae). Filiform papillae distributed on the anterior tongue and posterior of the lingual prominence consisted of a posterior thick main process and several small accessory processes. After removal of the epithelium, the CTCs of the filiform papillae had U-shaped, horseshoe-like primary cores with 10-15 rod-shaped small accessory cores. Large filiform papillae were distributed at the anterior margin of the lingual prominence. Dome-like papillae were distributed at the top of lingual prominence. Fungiform papillae were observed two types. Fungiform papillae, which were distributed at the anterior tongue, were round shaped. Fungiform papillae of the posterior of the lingual prominence were large and surrounded with a papillary groove. At the posterior of the tongue, three vallate papillae were arranged in a triangular pattern. Foliate papillae were on 22 to 25 parallel ridges and grooves.

  19. Interannual and long-term changes in the trophic state of a multibasin lake: Effects of morphology, climate, winter aeration, and beaver activity

    USGS Publications Warehouse

    Robertson, Dale; Rose, William; Reneau, Paul C.

    2016-01-01

    Little St. Germain Lake (LSG), a relatively pristine multibasin lake in Wisconsin, USA, was examined to determine how morphologic (internal), climatic (external), anthropogenic (winter aeration), and natural (beaver activity) factors affect the trophic state (phosphorus, P; chlorophyll, CHL; and Secchi depth, SD) of each of its basins. Basins intercepting the main flow and external P sources had highest P and CHL and shallowest SD. Internal loading in shallow, polymictic basins caused P and CHL to increase and SD to decrease as summer progressed. Winter aeration used to eliminate winterkill increased summer internal P loading and decreased water quality, while reductions in upstream beaver impoundments had little effect on water quality. Variations in air temperature and precipitation affected each basin differently. Warmer air temperatures increased productivity throughout the lake and decreased clarity in less eutrophic basins. Increased precipitation increased P in the basins intercepting the main flow but had little effect on the isolated deep West Bay. These relations are used to project effects of future climatic changes on LSG and other temperate lakes.

  20. Unusual odd-chain and trans-octadecenoic fatty acids in tissues of feral European beaver (Castorfiber), Eurasian badger (Melesmeles) and raccoon dog (Nyctereutesprocyonoides).

    PubMed

    Martysiak-Zurowska, Dorota; Zalewski, Kazimierz; Kamieniarz, Robert

    2009-06-01

    The fatty acid (FA) composition of depot adipose tissues in the raccoon dog (Nyctereutesprocyonoides) and the European beaver (Castorfiber) differs from that reported for the lipids of other monogastric animals, especially with regard to the presence of trans-octadecenoic acids. The concentrations of pentadecanoic acid 15:0 (PA) and heptadecanoic acid 17:0 (HA) in the lipids of the tested animals ranged from 0.23 to 0.79% and from 0.33 to 2.35% of total FAs, respectively. The total content of their monounsaturated cis isomers varied from 0.12 to 2.75% for pentadecanoic acid (c-PA) and from 0.38 to 2.45% for heptadecanoic acid (c-HA). It is interesting that the tissues of European beavers and raccoon dogs contained also trans isomers of octadecenoic acid C18:1 (t-OA) including vaccenic acid C18:1,11t (VA), typical of ruminants. The presence of FAs with an uneven number of carbon atoms and trans-octadecenoic acids in depot adipose tissue is indicative of the process of hydrogenation of polyunsaturated fatty acids (linoleic acid and alpha-linolenic acid) in the digestive tract. The tissues of badgers also contained t-OA (from below 0.05% in the liver to 0.44% in the kidneys), but no VA was found.

  1. REACTOR BASE, SOUTHEAST CORNER. INTERIOR WILL CONTAIN REACTOR TANK, COOLING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    REACTOR BASE, SOUTHEAST CORNER. INTERIOR WILL CONTAIN REACTOR TANK, COOLING WATER PIPES, COOLING AIR DUCTS, AND SHIELDING. INL NEGATIVE NO. 776. Unknown Photographer, 10/1950 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

  2. Nuclear reactor control column

    DOEpatents

    Bachovchin, Dennis M.

    1982-01-01

    The nuclear reactor control column comprises a column disposed within the nuclear reactor core having a variable cross-section hollow channel and containing balls whose vertical location is determined by the flow of the reactor coolant through the column. The control column is divided into three basic sections wherein each of the sections has a different cross-sectional area. The uppermost section of the control column has the greatest cross-sectional area, the intermediate section of the control column has the smallest cross-sectional area, and the lowermost section of the control column has the intermediate cross-sectional area. In this manner, the area of the uppermost section can be established such that when the reactor coolant is flowing under normal conditions therethrough, the absorber balls will be lifted and suspended in a fluidized bed manner in the upper section. However, when the reactor coolant flow falls below a predetermined value, the absorber balls will fall through the intermediate section and into the lowermost section, thereby reducing the reactivity of the reactor core and shutting down the reactor.

  3. Reactor Safety Research Programs

    SciTech Connect

    Edler, S. K.

    1981-07-01

    This document summarizes the work performed by Pacific Northwest Laboratory (PNL) from January 1 through March 31, 1981, for the Division of Reactor Safety Research within the U.S. Nuclear Regulatory Commission (NRC). Evaluations of nondestructive examination (NDE) techniques and instrumentation are reported; areas of investigation include demonstrating the feasibility of determining the strength of structural graphite, evaluating the feasibility of detecting and analyzing flaw growth in reactor pressure boundary systems, examining NDE reliability and probabilistic fracture mechanics, and assessing the integrity of pressurized water reactor (PWR) steam generator tubes where service-induced degradation has been indicated. Experimental data and analytical models are being provided to aid in decision-making regarding pipeto- pipe impacts following postulated breaks in high-energy fluid system piping. Core thermal models are being developed to provide better digital codes to compute the behavior of full-scale reactor systems under postulated accident conditions. Fuel assemblies and analytical support are being provided for experimental programs at other facilities. These programs include loss-ofcoolant accident (LOCA) simulation tests at the NRU reactor, Chalk River, Canada; fuel rod deformation, severe fuel damage, and postaccident coolability tests for the ESSOR reactor Super Sara Test Program, Ispra, Italy; the instrumented fuel assembly irradiation program at Halden, Norway; and experimental programs at the Power Burst Facility, Idaho National Engineering Laboratory (INEL). These programs will provide data for computer modeling of reactor system and fuel performance during various abnormal operating conditions.

  4. Slurry reactor design studies

    SciTech Connect

    Fox, J.M.; Degen, B.D.; Cady, G.; Deslate, F.D.; Summers, R.L. ); Akgerman, A. ); Smith, J.M. )

    1990-06-01

    The objective of these studies was to perform a realistic evaluation of the relative costs of tublar-fixed-bed and slurry reactors for methanol, mixed alcohols and Fischer-Tropsch syntheses under conditions where they would realistically be expected to operate. The slurry Fischer-Tropsch reactor was, therefore, operated at low H{sub 2}/CO ratio on gas directly from a Shell gasifier. The fixed-bed reactor was operated on 2.0 H{sub 2}/CO ratio gas after adjustment by shift and CO{sub 2} removal. Every attempt was made to give each reactor the benefit of its optimum design condition and correlations were developed to extend the models beyond the range of the experimental pilot plant data. For the methanol design, comparisons were made for a recycle plant with high methanol yield, this being the standard design condition. It is recognized that this is not necessarily the optimum application for the slurry reactor, which is being proposed for a once-through operation, coproducing methanol and power. Consideration is also given to the applicability of the slurry reactor to mixed alcohols, based on conditions provided by Lurgi for an Octamix{trademark} plant using their standard tubular-fixed reactor technology. 7 figs., 26 tabs.

  5. NUCLEAR REACTOR FUEL SYSTEMS

    DOEpatents

    Thamer, B.J.; Bidwell, R.M.; Hammond, R.P.

    1959-09-15

    Homogeneous reactor fuel solutions are reported which provide automatic recombination of radiolytic gases and exhibit large thermal expansion characteristics, thereby providing stability at high temperatures and enabling reactor operation without the necessity of apparatus to recombine gases formed by the radiolytic dissociation of water in the fuel and without the necessity of liquid fuel handling outside the reactor vessel except for recovery processes. The fuels consist of phosphoric acid and water solutions of enriched uranium, wherein the uranium is in either the hexavalent or tetravalent state.

  6. NEUTRONIC REACTOR CONTROL

    DOEpatents

    Metcalf, H.E.

    1958-10-14

    Methods of controlling reactors are presented. Specifically, a plurality of neutron absorber members are adjustably disposed in the reactor core at different distances from the center thereof. The absorber members extend into the core from opposite faces thereof and are operated by motive means coupled in a manner to simultaneously withdraw at least one of the absorber members while inserting one of the other absorber members. This feature effects fine control of the neutron reproduction ratio by varying the total volume of the reactor effective in developing the neutronic reaction.

  7. Microfluidic electrochemical reactors

    SciTech Connect

    Nuzzo, Ralph G; Mitrovski, Svetlana M

    2011-03-22

    A microfluidic electrochemical reactor includes an electrode and one or more microfluidic channels on the electrode, where the microfluidic channels are covered with a membrane containing a gas permeable polymer. The distance between the electrode and the membrane is less than 500 micrometers. The microfluidic electrochemical reactor can provide for increased reaction rates in electrochemical reactions using a gaseous reactant, as compared to conventional electrochemical cells. Microfluidic electrochemical reactors can be incorporated into devices for applications such as fuel cells, electrochemical analysis, microfluidic actuation, pH gradient formation.

  8. Nuclear reactor reflector

    DOEpatents

    Hopkins, R.J.; Land, J.T.; Misvel, M.C.

    1994-06-07

    A nuclear reactor reflector is disclosed that comprises a stack of reflector blocks with vertical water flow passages to cool the reflector. The interface between blocks is opposite support points for reactor fuel rods. Water flows between the reflector and the reactor barrel from passages in a bottom block. The top block contains a flange to limit this flow and the flange has a slot to receive an alignment pin that is welded to the barrel. The pin is held in the slot by two removable shims. Alignment bars extend the length of the stack in slots machined in each block when the stack is assembled. 12 figs.

  9. Nuclear reactor reflector

    DOEpatents

    Hopkins, Ronald J.; Land, John T.; Misvel, Michael C.

    1994-01-01

    A nuclear reactor reflector is disclosed that comprises a stack of reflector blocks with vertical water flow passages to cool the reflector. The interface between blocks is opposite support points for reactor fuel rods. Water flows between the reflector and the reactor barrel from passages in a bottom block. The top block contains a flange to limit this flow and the flange has a slot to receive an alignment pin that is welded to the barrel. The pin is held in the slot by two removable shims. Alignment bars extend the length of the stack in slots machined in each block when the stack is assembled.

  10. COOLED NEUTRONIC REACTOR

    DOEpatents

    Binner, C.R.; Wilkie, C.B.

    1958-03-18

    This patent relates to a design for a reactor of the type in which a fluid coolant is flowed through the active portion of the reactor. This design provides for the cooling of the shielding material as well as the reactor core by the same fluid coolant. The core structure is a solid moderator having coolant channels in which are disposed the fuel elements in rod or slug form. The coolant fluid enters the chamber in the shield, in which the core is located, passes over the inner surface of said chamber, enters the core structure at the center, passes through the coolant channels over the fuel elements and out through exhaust ducts.

  11. REACTOR CONTROL SYSTEM

    DOEpatents

    MacNeill, J.H.; Estabrook, J.Y.

    1960-05-10

    A reactor control system including a continuous tape passing through a first coolant passageway, over idler rollers, back through another parallel passageway, and over motor-driven rollers is described. Discrete portions of fuel or poison are carried on two opposed active sections of the tape. Driving the tape in forward or reverse directions causes both active sections to be simultaneously inserted or withdrawn uniformly, tending to maintain a more uniform flux within the reactor. The system is particularly useful in mobile reactors, where reduced inertial resistance to control rod movement is important.

  12. Retrofit Russian research reactors

    SciTech Connect

    Mabe, W.

    1993-04-01

    A likely source for enriched uranium for production of a gun-type bomb might be a research reactor. A state or terrorist organization would find the technical process for separating uranium from the reactor fuel plates is simple and well-published. An unguarded research reactor could be found in the former Soviet Union. Russia and the former republics have seen an increasing number of terrorist incidents, including hijackings and bombings. Recognizing the danger, Russia and the U.S. have explored means of safeguarding former Soviet weapons materials. This article describes some of the plans to reduce the risk of nuclear materials being obtained for illicit weapons production.

  13. Fast Breeder Reactor studies

    SciTech Connect

    Till, C.E.; Chang, Y.I.; Kittel, J.H.; Fauske, H.K.; Lineberry, M.J.; Stevenson, M.G.; Amundson, P.I.; Dance, K.D.

    1980-07-01

    This report is a compilation of Fast Breeder Reactor (FBR) resource documents prepared to provide the technical basis for the US contribution to the International Nuclear Fuel Cycle Evaluation. The eight separate parts deal with the alternative fast breeder reactor fuel cycles in terms of energy demand, resource base, technical potential and current status, safety, proliferation resistance, deployment, and nuclear safeguards. An Annex compares the cost of decommissioning light-water and fast breeder reactors. Separate abstracts are included for each of the parts.

  14. Spherical torus fusion reactor

    DOEpatents

    Martin Peng, Y.K.M.

    1985-10-03

    The object of this invention is to provide a compact torus fusion reactor with dramatic simplification of plasma confinement design. Another object of this invention is to provide a compact torus fusion reactor with low magnetic field and small aspect ratio stable plasma confinement. In accordance with the principles of this invention there is provided a compact toroidal-type plasma confinement fusion reactor in which only the indispensable components inboard of a tokamak type of plasma confinement region, mainly a current conducting medium which carries electrical current for producing a toroidal magnet confinement field about the toroidal plasma region, are retained.

  15. CONTROL FOR NEUTRONIC REACTOR

    DOEpatents

    Lichtenberger, H.V.; Cameron, R.A.

    1959-03-31

    S>A control rod operating device in a nuclear reactor of the type in which the control rod is gradually withdrawn from the reactor to a position desired during stable operation is described. The apparatus is comprised essentially of a stop member movable in the direction of withdrawal of the control rod, a follower on the control rod engageable with the stop and means urging the follower against the stop in the direction of withdrawal. A means responsive to disengagement of the follower from the stop is provided for actuating the control rod to return to the reactor shut-down position.

  16. Orexin receptor expression in the hypothalamic-pituitary-adrenal and hypothalamic-pituitary-gonadal axes of free-living European beavers (Castor fiber L.) in different periods of the reproductive cycle.

    PubMed

    Czerwinska, Joanna; Chojnowska, Katarzyna; Kaminski, Tadeusz; Bogacka, Iwona; Smolinska, Nina; Kaminska, Barbara

    2017-01-01

    Orexins are hypothalamic neuropeptides acting via two G protein-coupled receptors in mammals: orexin receptor 1 (OX1R) and orexin receptor 2 (OX2R). In European beavers, which are seasonally breeding animals, the presence and functions of orexins and their receptors remain unknown. Our study aimed to determine the expression of OXR mRNAs and the localization of OXR proteins in hypothalamic-pituitary-adrenal/gonadal (HPA/HPG) axes in free-living beavers. The expression of OXR genes (OX1R, OX2R) and proteins was found in all analysed tissues during three periods of beavers' reproductive cycle (April, July, November). The expression of OXR mRNAs in the beaver HPA axis varied seasonally (P<0.05). The levels of OX1R mRNA also differed between the sexes (P<0.05). In the mediobasal hypothalamus, OX1R transcript content increased in pregnant females in April (P<0.05) and OX2R expression increased in males in July (P<0.05). In the pituitary and adrenals, OX1R mRNA levels were relatively constant in females and peaked in July in males (P<0.05), whereas the OX2R was most highly expressed in males in November and in females in April (P<0.05). In gonads, OX1R expression did not fluctuate between seasons or sexes, but transcript levels were elevated in the testes in November and in the ovaries in July (P<0.05). In turn, OX2R mRNA levels varied between the sexes (P<0.05) and were higher in females (July and November) than in males (P<0.05). The circannual variations in OXR mRNA levels in HPA and HPG axes suggest that the expression of these receptors is associated with sex-specific changes in beavers' reproductive activity and their environmental adaptations.

  17. NEUTRONIC REACTOR STRUCTURE

    DOEpatents

    Daniels, F.

    1961-10-24

    A reactor core, comprised of vertical stacks of hexagonal blocks of beryllium oxide having axial cylindrical apertures extending therethrough and cylindrical rods of a sintered mixture of uranium dioxide and beryllium oxide, is described. (AEC)

  18. Reactor Neutrino Spectra

    NASA Astrophysics Data System (ADS)

    Hayes, Anna C.; Vogel, Petr

    2016-10-01

    We present a review of the antineutrino spectra emitted from reactors. Knowledge of these spectra and their associated uncertainties is crucial for neutrino oscillation studies. The spectra used to date have been determined either by converting measured electron spectra to antineutrino spectra or by summing over all of the thousands of transitions that make up the spectra, using modern databases as input. The uncertainties in the subdominant corrections to β-decay plague both methods, and we provide estimates of these uncertainties. Improving on current knowledge of the antineutrino spectra from reactors will require new experiments. Such experiments would also address the so-called reactor neutrino anomaly and the possible origin of the shoulder observed in the antineutrino spectra measured in recent high-statistics reactor neutrino experiments.

  19. Packed Bed Reactor Experiment

    NASA Image and Video Library

    The purpose of the Packed Bed Reactor Experiment in low gravity is to determine how a mixture of gas and liquid flows through a packed bed in reduced gravity. A packed bed consists of a metal pipe ...

  20. NEUTRONIC REACTOR FUEL COMPOSITION

    DOEpatents

    Thurber, W.C.

    1961-01-10

    Uranium-aluminum alloys in which boron is homogeneously dispersed by adding it as a nickel boride are described. These compositions have particular utility as fuels for neutronic reactors, boron being present as a burnable poison.

  1. Catalytic Hydrogenation Retrofit Reactor

    SciTech Connect

    2001-02-01

    New Fixed-Bed Catalyst System Provides Significant Reduction in Energy and Hazard Exposure. Hydrogenation is an essential industrial reaction that is often performed using a slurry catalyst system in large stirred-tank reactors.

  2. Molten metal reactors

    SciTech Connect

    Bingham, Dennis N; Klingler, Kerry M; Turner, Terry D; Wilding, Bruce M

    2013-11-05

    A molten metal reactor for converting a carbon material and steam into a gas comprising hydrogen, carbon monoxide, and carbon dioxide is disclosed. The reactor includes an interior crucible having a portion contained within an exterior crucible. The interior crucible includes an inlet and an outlet; the outlet leads to the exterior crucible and may comprise a diffuser. The exterior crucible may contain a molten alkaline metal compound. Contained between the exterior crucible and the interior crucible is at least one baffle.

  3. Compact power reactor

    DOEpatents

    Wetch, Joseph R.; Dieckamp, Herman M.; Wilson, Lewis A.

    1978-01-01

    There is disclosed a small compact nuclear reactor operating in the epithermal neutron energy range for supplying power at remote locations, as for a satellite. The core contains fuel moderator elements of Zr hydride with 7 w/o of 93% enriched uranium alloy. The core has a radial beryllium reflector and is cooled by liquid metal coolant such as NaK. The reactor is controlled and shut down by moving portions of the reflector.

  4. K-Reactor readiness

    SciTech Connect

    Rice, P.D.

    1991-12-04

    This document describes some of the more significant accomplishments in the reactor restart program and details the magnitude and extent of the work completed to bring K-Reactor to a state of restart readiness. The discussion of restart achievements is organized into the three major categories of personnel, programs, and plant. Also presented is information on the scope and extent of internal and external oversight of the efforts, as well as some details on the startup plan.

  5. Future reactor experiments

    SciTech Connect

    Wen, Liangjian

    2015-07-15

    The non-zero neutrino mixing angle θ{sub 13} has been discovered and precisely measured by the current generation short-baseline reactor neutrino experiments. It opens the gate of measuring the leptonic CP-violating phase and enables the neutrino mass ordering. The JUNO and RENO-50 proposals aim at resolving the neutrino mass ordering using reactors. The experiment design, physics sensitivity, technical challenges as well as the progresses of those two proposed experiments are reviewed in this paper.

  6. K-Reactor readiness

    SciTech Connect

    Rice, P.D.

    1991-12-04

    This document describes some of the more significant accomplishments in the reactor restart program and details the magnitude and extent of the work completed to bring K-Reactor to a state of restart readiness. The discussion of restart achievements is organized into the three major categories of personnel, programs, and plant. Also presented is information on the scope and extent of internal and external oversight of the efforts, as well as some details on the startup plan.

  7. NEUTRONIC REACTOR CONSTRUCTION AND OPERATION

    DOEpatents

    West, J.M.; Weills, J.T.

    1960-03-15

    A method is given for operating a nuclear reactor having a negative coefficient of reactivity to compensate for the change in reactor reactivity due to the burn-up of the xenon peak following start-up of the reactor. When it is desired to start up the reactor within less than 72 hours after shutdown, the temperature of the reactor is lowered prior to start-up, and then gradually raised after start-up.

  8. F Reactor Inspection

    ScienceCinema

    Grindstaff, Keith; Hathaway, Boyd; Wilson, Mike

    2016-07-12

    Workers from Mission Support Alliance, LLC., removed the welds around the steel door of the F Reactor before stepping inside the reactor to complete its periodic inspection. This is the first time the Department of Energy (DOE) has had the reactor open since 2008. The F Reactor is one of nine reactors along the Columbia River at the Department's Hanford Site in southeastern Washington State, where environmental cleanup has been ongoing since 1989. As part of the Tri-Party Agreement, the Department completes surveillance and maintenance activities of cocooned reactors periodically to evaluate the structural integrity of the safe storage enclosure and to ensure confinement of any remaining hazardous materials. "This entry marks a transition of sorts because the Hanford Long-Term Stewardship Program, for the first time, was responsible for conducting the entry and surveillance and maintenance activities," said Keith Grindstaff, Energy Department Long-Term Stewardship Program Manager. "As the River Corridor cleanup work is completed and transitioned to long-term stewardship, our program will manage any on-going requirements."

  9. F Reactor Inspection

    SciTech Connect

    Grindstaff, Keith; Hathaway, Boyd; Wilson, Mike

    2014-10-29

    Workers from Mission Support Alliance, LLC., removed the welds around the steel door of the F Reactor before stepping inside the reactor to complete its periodic inspection. This is the first time the Department of Energy (DOE) has had the reactor open since 2008. The F Reactor is one of nine reactors along the Columbia River at the Department's Hanford Site in southeastern Washington State, where environmental cleanup has been ongoing since 1989. As part of the Tri-Party Agreement, the Department completes surveillance and maintenance activities of cocooned reactors periodically to evaluate the structural integrity of the safe storage enclosure and to ensure confinement of any remaining hazardous materials. "This entry marks a transition of sorts because the Hanford Long-Term Stewardship Program, for the first time, was responsible for conducting the entry and surveillance and maintenance activities," said Keith Grindstaff, Energy Department Long-Term Stewardship Program Manager. "As the River Corridor cleanup work is completed and transitioned to long-term stewardship, our program will manage any on-going requirements."

  10. Reactor Safety Research Programs

    SciTech Connect

    Dotson, CW

    1980-08-01

    This document summarizes the work performed by Pacific Northwest laboratory from October 1 through December 31, 1979, for the Division of Reactor Safety Research within the Nuclear Regulatory Commission. Evaluation of nondestructive examination (NDE) techniques and instrumentation are reported; areas of investigation include demonstrating the feasibilty of determining structural graphite strength, evaluating the feasibilty of detecting and analyzing flaw growth in reactor pressure boundary systems, examining NDE reliability and probabilistic fracture mechanics, and assessing the remaining integrity of pressurized water reactor steam generator tubes where service-induced degradation has been indicated. Test assemblies and analytical support are being provided for experimental programs at other facilities. These programs include the loss-of-coolant accident simulation tests at the NRU reactor, Chalk River, Canada; the fuel rod deformation and post-accident coolability tests for the ESSOR Test Reactor Program, lspra, Italy; the blowdown and reflood tests in the test facility at Cadarache, France; the instrumented fuel assembly irradiation program at Halden, Norway; and the experimental programs at the Power Burst Facility, Idaho National Engineering Laboratory. These programs will provide data for computer modeling of reactor system and fuel performance during various abnormal operating conditions.

  11. Moon base reactor system

    NASA Technical Reports Server (NTRS)

    Chavez, H.; Flores, J.; Nguyen, M.; Carsen, K.

    1989-01-01

    The objective of our reactor design is to supply a lunar-based research facility with 20 MW(e). The fundamental layout of this lunar-based system includes the reactor, power conversion devices, and a radiator. The additional aim of this reactor is a longevity of 12 to 15 years. The reactor is a liquid metal fast breeder that has a breeding ratio very close to 1.0. The geometry of the core is cylindrical. The metallic fuel rods are of beryllium oxide enriched with varying degrees of uranium, with a beryllium core reflector. The liquid metal coolant chosen was natural lithium. After the liquid metal coolant leaves the reactor, it goes directly into the power conversion devices. The power conversion devices are Stirling engines. The heated coolant acts as a hot reservoir to the device. It then enters the radiator to be cooled and reenters the Stirling engine acting as a cold reservoir. The engines' operating fluid is helium, a highly conductive gas. These Stirling engines are hermetically sealed. Although natural lithium produces a lower breeding ratio, it does have a larger temperature range than sodium. It is also corrosive to steel. This is why the container material must be carefully chosen. One option is to use an expensive alloy of cerbium and zirconium. The radiator must be made of a highly conductive material whose melting point temperature is not exceeded in the reactor and whose structural strength can withstand meteor showers.

  12. Moon base reactor system

    NASA Technical Reports Server (NTRS)

    Chavez, H.; Flores, J.; Nguyen, M.; Carsen, K.

    1989-01-01

    The objective of our reactor design is to supply a lunar-based research facility with 20 MW(e). The fundamental layout of this lunar-based system includes the reactor, power conversion devices, and a radiator. The additional aim of this reactor is a longevity of 12 to 15 years. The reactor is a liquid metal fast breeder that has a breeding ratio very close to 1.0. The geometry of the core is cylindrical. The metallic fuel rods are of beryllium oxide enriched with varying degrees of uranium, with a beryllium core reflector. The liquid metal coolant chosen was natural lithium. After the liquid metal coolant leaves the reactor, it goes directly into the power conversion devices. The power conversion devices are Stirling engines. The heated coolant acts as a hot reservoir to the device. It then enters the radiator to be cooled and reenters the Stirling engine acting as a cold reservoir. The engines' operating fluid is helium, a highly conductive gas. These Stirling engines are hermetically sealed. Although natural lithium produces a lower breeding ratio, it does have a larger temperature range than sodium. It is also corrosive to steel. This is why the container material must be carefully chosen. One option is to use an expensive alloy of cerbium and zirconium. The radiator must be made of a highly conductive material whose melting point temperature is not exceeded in the reactor and whose structural strength can withstand meteor showers.

  13. Mechanisms and Magnitude of Cenozoic Crustal Extension in the Vicinity of Lake Mead, Nevada and the Beaver Dam Mountains, Utah: Geochemical, Geochronological,Thermochronological and Geophysical Constraints

    NASA Astrophysics Data System (ADS)

    Almeida, Rafael V.

    The central Basin and Range Province of Nevada and Utah was one of the first areas in which the existence of widespread low-angle normal faults or detachments was first recognized. The magnitude of associated crustal extension is estimated by some to be large, in places increasing original line lengths by as much as a factor of four. However, rock mechanics experiments and seismological data cast doubt on whether these structures slipped at low inclination in the manner generally assumed. In this dissertation, I review the evidence for the presence of detachment faults in the Lake Mead and Beaver Dam Mountains areas and place constraints on the amount of extension that has occurred there since the Miocene. Chapter 1 deals with the source-provenance relationship between Miocene breccias cropping out close to Las Vegas, Nevada and their interpreted source at Gold Butte, currently located 65 km to the east. Geochemical, geochronological and thermochronological data provide support for that long-accepted correlation, though with unexpected mismatches requiring modification of the original hypothesis. In Chapter 2, the same data are used to propose a refinement of the timing of ~1.45 Ga anorogenic magmatism, and the distribution of Proterozoic crustal boundaries. Chapter 3 uses geophysical methods to address the subsurface geometry of faults along the west flank of the Beaver Dam Mountains of southwestern Utah. The data suggest that the range is bounded by steeply inclined normal faults rather than a regional-scale detachment fault. Footwall folding formerly ascribed to Miocene deformation is reinterpreted as an expression of Cretaceous crustal shortening. Fission track data presented in Chapter 4 are consistent with mid-Miocene exhumation adjacent to high-angle normal faults. They also reveal a protracted history dating back to the Pennsylvanian-Permian time, with implications for the interpretation of other basement-cored uplifts in the region. A key finding of this

  14. Synthesis of monthly and annual streamflow records (water years 1950-2003) for Big Sandy, Clear, Peoples, and Beaver Creeks in the Milk River basin, Montana

    USGS Publications Warehouse

    Parrett, Charles

    2006-01-01

    To address concerns expressed by the State of Montana about the apportionment of water in the St. Mary and Milk River basins between Canada and the United States, the International Joint Commission requested information from the United States government about water that originates in the United States but does not cross the border into Canada. In response to this request, the U.S. Geological Survey synthesized monthly and annual streamflow records for Big Sandy, Clear, Peoples, and Beaver Creeks, all of which are in the Milk River basin in Montana, for water years 1950-2003. This report presents the synthesized values of monthly and annual streamflow for Big Sandy, Clear, Peoples, and Beaver Creeks in Montana. Synthesized values were derived from recorded and estimated streamflows. Statistics, including long-term medians and averages and flows for various exceedance probabilities, were computed from the synthesized data. Beaver Creek had the largest median annual discharge (19,490 acre-feet), and Clear Creek had the smallest median annual discharge (6,680 acre-feet). Big Sandy Creek, the stream with the largest drainage area, had the second smallest median annual discharge (9,640 acre-feet), whereas Peoples Creek, the stream with the second smallest drainage area, had the second largest median annual discharge (11,700 acre-feet). The combined median annual discharge for the four streams was 45,400 acre-feet. The largest combined median monthly discharge for the four creeks was 6,930 acre-feet in March, and the smallest combined median monthly discharge was 48 acre-feet in January. The combined median monthly values were substantially smaller than the average monthly values. Overall, synthesized flow records for the four creeks are considered to be reasonable given the prevailing climatic conditions in the region during the 1950-2003 base period. Individual estimates of monthly streamflow may have large errors, however. Linear regression was used to relate

  15. The effect of vegetation and beaver dams on geomorphic recovery rates of incised streams in the semi-arid regions of the Columbia River basin, USA.

    NASA Astrophysics Data System (ADS)

    Pollock, M.; Beechie, T.; Jordan, C.

    2005-05-01

    Channel incision is a common occurrence in semi-arid regions of the Columbia River basin and throughout the world, where a fragile balance between climate, vegetation and geology makes channels susceptible to changes in hillslope erosion, stream discharge and sediment yield. Incision is defined as a rapid downcutting and lowering of the stream bed such that it reduces the frequency and duration of flooding onto the adjacent floodplain. We are studying the feasibility of restoring incised streams throughout the interior Columbia River basin. We hypothesize that under proper land use management, it is possible for them to aggrade such that they reconnect to their former floodplains within relatively short time frames. Theoretical and empirical evidence suggests that over decadal time scales, changes to land management that excludes grazing and allows riparian vegetation to become established can cause significant fill within the incised valleys. Preliminary modeling suggests that factors most affecting the length of time for an incised valley to completely aggrade and reconnect to its pre-incision floodplain are the depth of the incision, sediment production in the watershed, the amount and type of riparian vegetation, and the extent of beaver dam construction. While most natural resource and fisheries managers are aware of widespread incision throughout the Columbia River basin, the extent of incision within the range of the Pacific salmon is largely undocumented. However, we do know many incised streams that historically supported salmon no longer do so, and that habitat conditions are severely degraded in these incised streams. The historical record shows that numerous salmon-bearing streams in the semi-arid region of the interior Columbia River basin once contained narrow and deep, slowly meandering channels lined with cottonwoods, willows and/or sedges, contained numerous beaver dams, contained abundant and easily accessible off-channel habitat on the floodplain

  16. Reactor Safety Planning for Prometheus Project, for Naval Reactors Information

    SciTech Connect

    P. Delmolino

    2005-05-06

    The purpose of this letter is to submit to Naval Reactors the initial plan for the Prometheus project Reactor Safety work. The Prometheus project is currently developing plans for cold physics experiments and reactor prototype tests. These tests and facilities may require safety analysis and siting support. In addition to the ground facilities, the flight reactor units will require unique analyses to evaluate the risk to the public from normal operations and credible accident conditions. This letter outlines major safety documents that will be submitted with estimated deliverable dates. Included in this planning is the reactor servicing documentation and shipping analysis that will be submitted to Naval Reactors.

  17. REACTOR GROUT THERMAL PROPERTIES

    SciTech Connect

    Steimke, J.; Qureshi, Z.; Restivo, M.; Guerrero, H.

    2011-01-28

    Savannah River Site has five dormant nuclear production reactors. Long term disposition will require filling some reactor buildings with grout up to ground level. Portland cement based grout will be used to fill the buildings with the exception of some reactor tanks. Some reactor tanks contain significant quantities of aluminum which could react with Portland cement based grout to form hydrogen. Hydrogen production is a safety concern and gas generation could also compromise the structural integrity of the grout pour. Therefore, it was necessary to develop a non-Portland cement grout to fill reactors that contain significant quantities of aluminum. Grouts generate heat when they set, so the potential exists for large temperature increases in a large pour, which could compromise the integrity of the pour. The primary purpose of the testing reported here was to measure heat of hydration, specific heat, thermal conductivity and density of various reactor grouts under consideration so that these properties could be used to model transient heat transfer for different pouring strategies. A secondary purpose was to make qualitative judgments of grout pourability and hardened strength. Some reactor grout formulations were unacceptable because they generated too much heat, or started setting too fast, or required too long to harden or were too weak. The formulation called 102H had the best combination of characteristics. It is a Calcium Alumino-Sulfate grout that contains Ciment Fondu (calcium aluminate cement), Plaster of Paris (calcium sulfate hemihydrate), sand, Class F fly ash, boric acid and small quantities of additives. This composition afforded about ten hours of working time. Heat release began at 12 hours and was complete by 24 hours. The adiabatic temperature rise was 54 C which was within specification. The final product was hard and displayed no visible segregation. The density and maximum particle size were within specification.

  18. Prevalence and Degree of Hearing Loss Among Males in the Beaver Dam Cohort: A Comparison of Veterans and Non-Veterans

    PubMed Central

    Wilson, Richard H.; Noe, Colleen M.; Cruickshanks, Karen J.; Wiley, Terry L.; Nondahl, David M.

    2010-01-01

    The Epidemiology of Hearing Loss Study (EHLS) conducted in Beaver Dam, Wisconsin, was a population-based study that focused on the prevalence of hearing loss among 3,753 participants between 1993 and 1996. This paper reports the results of several auditory measures from 999 veteran and 590 non-veteran males 48 to 92 years of age included in the EHLS. The auditory measures included pure-tone thresholds, tympanometry and acoustic reflexes, word recognition in quiet and in competing message, and the Hearing Handicap Inventory for the Elderly (HHIE-S). Hearing loss in the auditory domains of pure-tone thresholds, word recognition in quiet, and word recognition in competing message increased with age but were not significantly different for the veterans and non-veterans. There were no significant differences between participant groups on the HHIE-S with mixed differences regarding hearing-aid usage. PMID:20848364

  19. Reconnaissance of ground-water quality at selected wells in the Beaver Creek watershed, Shelby, Fayette, Tipton, and Haywood counties, West Tennessee, July to August 1992

    USGS Publications Warehouse

    Fielder, A.M.; Roman-Mas, A. J.; Bennett, M.W.

    1994-01-01

    A reconnaissance of water-quality conditions of the water-table aquifer in the Beaver Creek watershed and other rural areas of Shelby, Fayette, Tipton, and Haywood Counties, Tennessee, was conducted during July and August 1992. The reconnaissance was conducted by the U.S. Geological Survey, in cooperation with the Tennessee Department of Agriculture and the University of Tennessee Agricultural Extension Service. The report presents data of selected water-quality constituents and properties of water samples collected from 398 domestic wells, located primarily in rural areas. Nitrate concentrations exceeded 10 milligrams per liter in water from 73 of the 398 wells. Fecal coliform and fecal streptococci bacteria were detected in water from 21 and 118 wells, respectively.

  20. [Patterns of morphological variability in reintroduced populations with two beaver subspecies Castor fiber orientoeuropaeus and Castor fiber belorussicus (Castoridae, Rodentia) as an example].

    PubMed

    Korablev, N P; Korablev, P N

    2012-01-01

    Taking as an example two beaver subspecies (Castor fiber orientoeuropaeus and Castor fiber belorussicus) with documented history of population formation, the patterns of morphological variability in translocated groups of mammals are studied. The variability of quantitative and qualitative traits in the formed populations is not characterized by a single direction. The main trend consists in increasing of adaptive norms diversity as related to body size. There observed a slight increase in the level of fluctuating asymmetry, reduction in polymorphism of nonmetric traits, and increase in fraction of rare aberrations. All these may be caused by inbreeding taking place during the period of prapopulations formation. The results of the study allow for considering the intraspecific differentiation as a consequence of adaptive variability (adaptatiogenesis) or subspecies hybridization. As for stochastic processes (genetic drift, founder effect), they seem to not influence the morphological variability significantly. The differences between discrete and dimensional traits are indicative of population groups' peculiarity.