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5,407 results on '"Peterson, B. J."'

1. Developing a robust sensor for infrared imaging bolometers.

Author

Wurden, G. A., Partesotti, G., Reimold, F., Mukai, K., Peterson, B. J., and Federici, F.

Subjects
INFRARED imaging, METAL foils, SUBSTRATES (Materials science), BOLOMETERS, POWER density
Abstract

A new type of large area sensor for infrared imaging bolometers has been developed. It replaces the thin and fragile free-standing metal foils, which typically have been used, with a multi-layer coated sapphire (or diamond) substrate. Sapphire is transparent to mid-infrared wavelengths, is robust against transients, and can be thick enough to even be the vacuum window. The primary radiation absorber is still a thin deposited metal layer, but now it is partially insulated from the supporting sapphire substrate by a black (carbon-based) layer, which also acts as a blackbody remitter. Test results indicate 6× more noise equivalent power density (estimated NEPD = 23 W/m2 at 5 ms camera exposure time, foil temperature decay time 60 ms) for a 2 μm gold-coated sapphire disk compared to estimated NEP = 4 W/m2 at 1.8 ms exposure time, with foil decay time 420 ms, for a nominal 2.5 μm thick platinum-free-standing foil. [ABSTRACT FROM AUTHOR]

Published
2024
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10. Effects of Hypoxia in Developing Swine

Author

Gootman, P. M., Gootman, N., Buckley, B. J., Peterson, B. J., Steele, A. M., Sica, A. L., Gandhi, M. R., Acker, Helmut, editor, Trzebski, Andrzej, editor, and O’Regan, Ronan G., editor

Published
1990
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14. 3D effects of edge magnetic field configuration on divertor/scrape-off layer transport and optimization possibilities for a future reactor

Author

KOBAYASHI, Masahiro, Xu, Y., IDA, Katsumi, Corre, Y., Feng, Y., Schmitz, O., Frerichs, H., Tabares, F.L., Evans, T.E., Coenen, J.W., Liang, Y., Bader, A., ITOH, Kimitaka, YAMADA, Hiroshi, Ghendrih, Ph., Ciraolo, G., Tafalla, D., Lopez-Fraguas, A., Guo, H.Y., Cui, Z.Y., Reiter, D., Asakura, N., Wenzel, U., MORITA, Shigeru, OHNO, Noriyasu, Peterson, B. J., MASUZAKI, Suguru, KOBAYASHI, Masahiro, Xu, Y., IDA, Katsumi, Corre, Y., Feng, Y., Schmitz, O., Frerichs, H., Tabares, F.L., Evans, T.E., Coenen, J.W., Liang, Y., Bader, A., ITOH, Kimitaka, YAMADA, Hiroshi, Ghendrih, Ph., Ciraolo, G., Tafalla, D., Lopez-Fraguas, A., Guo, H.Y., Cui, Z.Y., Reiter, D., Asakura, N., Wenzel, U., MORITA, Shigeru, OHNO, Noriyasu, Peterson, B. J., and MASUZAKI, Suguru

Abstract

This paper assesses the three-dimensional (3D) effects of the edge magnetic field structure on divertor/scrape-off layer transport, based on an inter-machine comparison of experimental data and on the recent progress of 3D edge transport simulation. The 3D effects are elucidated as a consequence of competition between transports parallel ($\parallel $ ) and perpendicular ($\bot $ ) to the magnetic field, in open field lines cut by divertor plates, or in magnetic islands. The competition has strong impacts on divertor functions, such as determination of the divertor density regime, impurity screening and detachment control. The effects of magnetic perturbation on the edge electric field and turbulent transport are also discussed. Parameterization to measure the 3D effects on the edge transport is attempted for the individual divertor functions. Based on the suggested key parameters, an operation domain of the 3D divertor configuration is discussed for future devices., source:M. Kobayashi et al 2015 Nucl. Fusion 55 104021, source:https://doi.org/10.1088/0029-5515/55/10/104021

Published
2021

16. Preliminary design of a tangentially viewing imaging bolometer for NSTX-U

Author

Peterson, B. J., Sano, R., Reinke, M.L., Canik, J.M., Delgado-Aparicio, L. F., Lore, J. D., Mukai, K., Gray, T.K., van Eden, G.G., Jaworski, M.A., Peterson, B. J., Sano, R., Reinke, M.L., Canik, J.M., Delgado-Aparicio, L. F., Lore, J. D., Mukai, K., Gray, T.K., van Eden, G.G., and Jaworski, M.A.

Abstract

The infrared imaging video bolometer (IRVB) measures plasma radiated power images using a thin metal foil. Two different designs with a tangential view of NSTX-U are made assuming a 640 × 480 (1280 × 1024) pixel, 30 (105) fps, 50 (20) mK, IR camera imaging the 9 cm × 9 cm × 2 μm Pt foil. The foil is divided into 40 × 40 (64 × 64) IRVB channels. This gives a spatial resolution of 3.4 (2.2) cm on the machine mid-plane. The noise equivalent power density of the IRVB is given as 113 (46) μW/cm2 for a time resolution of 33 (20) ms. Synthetic images derived from Scrape Off Layer Plasma Simulation data using the IRVB geometry show peak signal levels ranging from ∼0.8 to ∼80 (∼0.36 to ∼26) mW/cm2.

Published
2016

19. A model of the Arctic Ocean carbon cycle

Author

Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences, Manizza, Manfredi, Follows, Michael J, Dutkiewicz, Stephanie, Hill, Christopher N, Menemenlis, D., McClelland, J. W., Peterson, B. J., Key, R. M., Hill, Christopher N., Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences, Manizza, Manfredi, Follows, Michael J, Dutkiewicz, Stephanie, Hill, Christopher N, Menemenlis, D., McClelland, J. W., Peterson, B. J., Key, R. M., and Hill, Christopher N.

Abstract

A three dimensional model of Arctic Ocean circulation and mixing, with a horizontal resolution of 18 km, is overlain by a biogeochemical model resolving the physical, chemical and biological transport and transformations of phosphorus, alkalinity, oxygen and carbon, including the air-sea exchange of dissolved gases and the riverine delivery of dissolved organic carbon. The model qualitatively captures the observed regional and seasonal trends in surface ocean PO₄, dissolved inorganic carbon, total alkalinity, and pCO₂. Integrated annually, over the basin, the model suggests a net annual uptake of 59 Tg C a⁻¹, within the range of published estimates based on the extrapolation of local observations (20-199 Tg C a⁻¹). This flux is attributable to the cooling (increasing solubility) of waters moving into the basin, mainly from the subpolar North Atlantic. The air-sea flux is regulated seasonally and regionally by sea-ice cover, which modulates both air-sea gas transfer and the photosynthetic production of organic matter, and by the delivery of riverine dissolved organic carbon (RDOC), which drive the regional contrasts in pCO₂ between Eurasian and North American coastal waters. Integrated over the basin, the delivery and remineralization of RDOC reduces the net oceanic CO₂ uptake by ∼10%., National Science Foundation (U.S.) (Grant ARC-0531119), National Science Foundation (U.S.) (Grant ARC-0806229)

Published
2018

24. Compatibility between high energy particle confinement and magnetohydrodynamic stability in the inward-shifted plasmas of the Large Helical Device

Author

KANEKO, O., KOMORI, A., YAMADA, H., OHYABU, N., KAWAHATA, K., NAKAMURA, Y., IDA, K., MURAKAMI, S., MUTOH, T., SAKAKIBARA, S., Masuzaki, S., Ashikawa, N., Emoto, M., Funaba, H., Goto, M., Idei, H., Ikeda, K., Inagaki, S., Inoue, N., Isobe, M., Khlopenkov, K., Kubo, S., Kumazawa, R., Minami, T., Miyazawa, J., Morisaki, T., Morita, S., Muto, S., Nagayama, Y., Nakajima, N., Nakanishi, H., Narihara, K., Nishimura, K., Noda, N., Notake, T., Kobuchi, T., Liang, Y., Ohdachi, S., Oka, Y., Osakabe, M., Ozaki, T., Peterson, B. J., Sagara, A., Saito, K., Sakamoto, R., Sasao, M., Sato, K., Sato, M., Seki, T., SHIMOZUKA, T., SHOJI, M., Suzuki, H., Takechi, M., Takeiri, Y., Tamura, N., Tanaka, K., Toi, K., Tokuzawa, T., Torii, Y., Tsumori, K., Yamada, I., Yamamoto, S., Yokoyama, M., Yoshimura, Y., Yoshinuma, M., Watanabe, K.Y., Watari, T., Xu, Y., Itoh, K., Matsuoka, K., Ohkubo, K., Ohtake, I., Satow, T., Sudo, S., Yamazaki, K., Hamada, Y., Motojima, O., Fujiwara, M., O., Kaneko, A., KOMORI, H., YAMADA, N., Ohyabu, K., Kawahata, Y., Nakamura, K., Ida, S., Murakami, T., Mutoh, S., Sakakibara, S., Masuzaki, N., Ashikawa, M., Emoto, H., Funaba, M., Goto, H., Idei, K., Ikeda, S., Inagaki, N., Inoue, M., Isobe, K., Khlopenkov, S., Kubo, R., Kumazawa, T., Minami, J., Miyazawa, T., Morisaki, S., Morita, S., Muto, Y., Nagayama, N., Nakajima, H., Nakanishi, K., Narihara, K., Nishimura, N., Noda, T., Notake, T., Kobuchi, Y., Liang, S., Ohdachi, Y., Oka, M., Osakabe, T., Ozaki, B.J., Peterson, A., Sagara, K., Saito, R., Sakamoto, M., Sasao, K., Sato, M., Sato, T., Seki, T., Shimozuma, M., Shoji, H., Suzuki, M., Takechi, Y., Takeiri, N., Tamura, K., Tanaka, K., Toi, T., Tokuzawa, Y., Torii, K., Tsumori, I., Yamada, S., Yamamoto, M., Yokoyama, Y., Yoshimura, M., Yoshinuma, K.Y., Watanabe, T., Watari, Y., Xu, K., Itoh, K., Matsuoka, K., Ohkubo, I., Ohtake, T., Satow, S., Sudo, K., Yamazaki, Y., Hamada, O., Motojima, and M., Fujiwara

Subjects
Physics, High energy particle, Cyclotron, Plasma, Condensed Matter Physics, Neutral beam injection, Magnetic field, law.invention, Large Helical Device, law, Physics::Plasma Physics, Magnetohydrodynamic drive, Magnetohydrodynamics, Atomic physics
Abstract

The experimentally optimized magnetic field configuration of the Large Helical Device [A. Iiyoshi et al., Nucl. Fusion 39, 1245 (1999)], where the magnetic axis is shifted inward by 15 cm from the early theoretical prediction, reveals 50% better global energy confinement than the prediction of the scaling law. This configuration has been investigated further from the viewpoints of high energy particle confinement and magnetohydrodynamic (MHD) stability. The confinement of high energy ions is improved as expected. The minority heating of ion cyclotron range of frequency was successful and the heating efficiency was improved by the inward shift. The confinement of passing particles by neutral beam injection was also improved under low magnetic field strength, and there could be obtained an almost steady high beta discharge up to 3% in volume average. This was a surprising result because the observed pressure gradient exceeded the Mercier unstable limit. The observed MHD activities became as high as beta but they did not grow enough to deteriorate the confinement of high energy ions or the performance of the bulk plasma, which was still 50% better than the scaling. According to these favorable results, better performance would be expected by increasing the heating power because the neoclassical transport can also be improved there.

Published
2002

25. Consistencies in the dietary and isotopic niche of spotted seatrout, Cynoscion nebulosus, across a salinity gradient within a coastal Louisiana estuary.

Author

MacRae PSD, Russell M, Cowan JH Jr, Fry B, Moyo S, and Polito MJ

Subjects
Animals, Louisiana, Perciformes physiology, Food Chain, Gastrointestinal Contents chemistry, Carbon Isotopes analysis, Nitrogen Isotopes analysis, Salinity, Estuaries, Diet
Abstract

Estuaries are essential habitats for recreational and commercial fish that are shaped by both natural and anthropogenic processes. In Louisiana a combination of climate change and planned coastal restoration actions is predicted to increase freshwater introduction to coastal estuaries. As such there is a need to quantify the relationships between estuarine fish ecology and salinity to aid in predicting how species will respond to shifts in salinity. We investigated the relative abundance and dietary niches of adult (24.5 ± 5.4 cm standard length) spotted seatrout Cynoscion nebulosus across varying salinity regimes (oligohaline, mesohaline, and polyhaline) within Barataria Bay, Louisiana, using a combination of net sampling and gut content and stable isotopes analysis. We found that the relative abundance of C. nebulosus was lowest at the oligohaline site, translating to approximately five fewer fish captured for every single psu decrease in a site's average annual salinity. In contrast, we found that diets and, to a lesser extent, isotopic niches had a high degree of overlap across sites with differing salinity regimes. Fish and penaeid shrimp were the most common and important prey taxa recovered from guts at all sites. The small isotopic differences found among sites were likely due to spatial variation in hydrogeochemical baselines, and the observed isotopic overlap provides support for the idea that C. nebulosus move between adjacent salinity regimes and forage throughout Barataria Bay. Our results contribute to a greater understanding of the salinity preference and trophic ecology of C. nebulosus that can aid in predicting their responses to future salinity and habitat changes within Barataria Bay associated with predicted climate change and planned coastal restoration actions., (© 2024 Fisheries Society of the British Isles.)

Published
2024
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29. Particulate organic carbon and nitrogen export from major Arctic rivers

Author

McClelland, J. W., primary, Holmes, R. M., additional, Peterson, B. J., additional, Raymond, P. A., additional, Striegl, R. G., additional, Zhulidov, A. V., additional, Zimov, S. A., additional, Zimov, N., additional, Tank, S. E., additional, Spencer, R. G. M., additional, Staples, R., additional, Gurtovaya, T. Y., additional, and Griffin, C. G., additional

Published
2016
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30. Modeling transport and fate of riverine dissolved organic carbon in the Arctic Ocean

Author

Massachusetts Institute of Technology. Center for Global Change Science, Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences, Manizza, Manfredi, Follows, Michael J., Dutkiewicz, Stephanie, Hill, Christopher N., McClelland, J. W., Menemenlis, Dimitris, Townsend-Small, A., Peterson, B. J., Follows, Michael J, Massachusetts Institute of Technology. Center for Global Change Science, Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences, Manizza, Manfredi, Follows, Michael J., Dutkiewicz, Stephanie, Hill, Christopher N., McClelland, J. W., Menemenlis, Dimitris, Townsend-Small, A., Peterson, B. J., and Follows, Michael J

Abstract

The spatial distribution and fate of riverine dissolved organic carbon (DOC) in the Arctic may be significant for the regional carbon cycle but are difficult to fully characterize using the sparse observations alone. Numerical models of the circulation and biogeochemical cycles of the region can help to interpret and extrapolate the data and may ultimately be applied in global change sensitivity studies. Here we develop and explore a regional, three-dimensional model of the Arctic Ocean in which, for the first time, we explicitly represent the sources of riverine DOC with seasonal discharge based on climatological field estimates. Through a suite of numerical experiments, we explore the distribution of DOC-like tracers with realistic riverine sources and a simple linear decay to represent remineralization through microbial degradation. The model reproduces the slope of the DOC-salinity relationship observed in the eastern and western Arctic basins when the DOC tracer lifetime is about 10 years, consistent with published inferences from field data. The new empirical parameterization of riverine DOC and the regional circulation and biogeochemical model provide new tools for application in both regional and global change studies., National Science Foundation (U.S.)

Published
2015

31. Western interior design awards

Author

Holec, LuAnn Thoma, Lueck, Odette, Peterson, B. J., Sechrist, Melinda, Bertelsen, Ann, Gregory, Daniel, and Whiteley, Peter O.

Subjects
Interior design -- Achievements and awards
Abstract

Winners in our first program sponsored with the American Society of Interior Designers hail from Arizona, California, New Mexico, and Texas Two years ago, Sunset journeyed to the headquarters of […]

Published
2000

32. An analysis of the carbon balance of the Arctic Basin from 1997 to 2006

Author

Massachusetts Institute of Technology. Center for Global Change Science, Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences, Manizza, Manfredi, Follows, Michael J., Prinn, Ronald G., McGuire, A. David, Hayes, D. J., Kicklighter, David, Zhuang, Q., Chen, M., Gurney, K. R., McClelland, J. W., Melillo, Jerry M., Peterson, B. J., Follows, Michael J, Prinn, Ronald G, Massachusetts Institute of Technology. Center for Global Change Science, Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences, Manizza, Manfredi, Follows, Michael J., Prinn, Ronald G., McGuire, A. David, Hayes, D. J., Kicklighter, David, Zhuang, Q., Chen, M., Gurney, K. R., McClelland, J. W., Melillo, Jerry M., Peterson, B. J., Follows, Michael J, and Prinn, Ronald G

Abstract

This study used several model-based tools to analyse the dynamics of the Arctic Basin between 1997 and 2006 as a linked system of land-ocean-atmosphere C exchange. The analysis estimates that terrestrial areas of the Arctic Basin lost 62.9 Tg C yr[superscript -1] and that the Arctic Ocean gained 94.1 Tg C yr[superscript -1]. Arctic lands and oceans were a net CO[subscript 2] sink of 108.9 Tg C yr[superscript -1], which is within the range of uncertainty in estimates from atmospheric inversions. Although both lands and oceans of the Arctic were estimated to be CO[subscript 2] sinks, the land sink diminished in strength because of increased fire disturbance compared to previous decades, while the ocean sink increased in strength because of increased biological pump activity associated with reduced sea ice cover. Terrestrial areas of the Arctic were a net source of 41.5 Tg CH[subscript 4] yr[superscript -1] that increased by 0.6 Tg CH[subscript 4] yr[superscript -1] during the decade of analysis, a magnitude that is comparable with an atmospheric inversion of CH[subscript 4]. Because the radiative forcing of the estimated CH[subscript 4] emissions is much greater than the CO[subscript 2] sink, the analysis suggests that the Arctic Basin is a substantial net source of green house gas forcing to the climate system., National Science Foundation (U.S.) (Arctic Carbon Cycle Synthesis Project ARC-0531047), National Science Foundation (U.S.) (Arctic Carbon Cycle Synthesis Project ARC-0531082), National Science Foundation (U.S.) (Arctic Carbon Cycle Synthesis Project ARC-0531119), National Science Foundation (U.S.) (Arctic Carbon Cycle Synthesis Project ARC-0554811)

Published
2014

34. Inter-biome comparison of factors controlling stream metabolism

Author

Mulholland, P. J., Fellows, C. S., Tank, J. L., Grimm, N. B., Webster, J. R., Hamilton, S. K., Martí, Eugènia, Ashkenas, L., Bowden, W. B., Dodds, W. K., McDowell, W. H., Paul, M. J., and Peterson, B. J.

Subjects
Metabolism, Primary production, Respiration, Stream, Inter-biome
Abstract

14 Páginas ; 6 Figuras ; 2 Tablas, 1. We studied whole-ecosystem metabolism in eight streams from several biomes in North America to identify controls on the rate of stream metabolism over a large geographic range. The streams studied had climates ranging from tropical to cool-temperate and from humid to arid and were all relatively uninfluenced by human disturbances. 2. Rates of gross primary production (GPP), ecosystem respiration (R) and net ecosystem production (NEP) were determined using the open-system, two-station diurnal oxygen change method. 3. Three general patterns in metabolism were evident among streams: (1) relatively high GPP with positive NEP (i.e. net oxygen production) in early afternoon, (2) moderate primary production with a distinct peak in GPP during daylight but negative NEP at all times and (3) little or no evidence of GPP during daylight and a relatively constant and negative NEP over the entire day. 4. Gross primary production was most strongly correlated with photosynthetically active radiation (PAR). A multiple regression model that included log PAR and stream water soluble reactive phosphorus (SRP) concentration explained 90% of the variation in log GPP. 5. Ecosystem respiration was significantly correlated with SRP concentration and size of the transient storage zone and, together, these factors explained 73% of the variation in R. The rate of R was poorly correlated with the rate of GPP. 6. Net ecosystem production was significantly correlated only with PAR, with 53% of the variation in log NEP explained by log PAR. Only Sycamore Creek, a desert stream in Arizona, had positive NEP (GPP: R > 1), supporting the idea that streams are generally net sinks rather than net sources of organic matter. 7. Our results suggest that light, phosphorus concentration and channel hydraulics are important controls on the rate of ecosystem metabolism in streams over very extensive geographic areas., The Ecosystems Program, National Science Foundation, to Virginia Tech (DEB-9628860). The research was conducted in part on the Oak Ridge National Environmental Research Park, Environmental Sciences Division, Office of Biological and Environmental Research, U.S. Department of Energy under contract DE-AC05–00OR2725 with University of Tennessee-Battelle LLC.

Published
2008

35. Fluid features of the stochastic layer transport in LHD

Author

Feng, Y., Kobayashi, M., Morisaki, T., Masuzaki, S., Miyazawa, J., Peterson, B. J., Morita, S., Shoji, M., Ida, K., Yamada, I., Narihara, K., Ashikawa, N., Yamada, H., Ohyabu, N., Komori, A., Morojima, O., Sardei, F., Reiter, D., and LHD Experimental Group

Published
2008

36. River export of nutrients and organic matter from the North Slope of Alaska to the Beaufort Sea.

Author

McClelland, J. W., Townsend-Small, A., Holmes, R. M., Pan, Feifei, Stieglitz, M., Khosh, M., and Peterson, B. J.

Subjects
NUTRIENT pollution of water, DISSOLVED organic matter, RIVERS
Abstract

While river-borne materials are recognized as important resources supporting coastal ecosystems around the world, estimates of river export from the North Slope of Alaska have been limited by a scarcity of water chemistry and river discharge data. This paper quantifies water, nutrient, and organic matter export from the three largest rivers (Sagavanirktok, Kuparuk, and Colville) that drain Alaska's North Slope and discusses the potential importance of river inputs for biological production in coastal waters of the Alaskan Beaufort Sea. Together these rivers export ∼297,000 metric tons of organic carbon and ∼18,000 metric tons of organic nitrogen each year. Annual fluxes of nitrate-N, ammonium-N, and soluble reactive phosphorus are approximately 1750, 200, and 140 metric tons per year, respectively. Constituent export from Alaska's North Slope is dominated by the Colville River. This is in part due to its larger size, but also because constituent yields are greater in the Colville watershed. River-supplied nitrogen may be more important to productivity along the Alaskan Beaufort Sea coast than previously thought. However, given the dominance of organic nitrogen export, the potential role of river-supplied nitrogen in support of primary production depends strongly on remineralization mechanisms. Although rivers draining the North Slope of Alaska make only a small contribution to overall river export from the pan-arctic watershed, comparisons with major arctic rivers reveal unique regional characteristics as well as remarkable similarities among different regions and scales. Such information is crucial for development of robust river export models that represent the arctic system as a whole. [ABSTRACT FROM AUTHOR]

Published
2014
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38. A global synthesis of predation on bivalves.

Author

Meira A, Byers JE, and Sousa R

Subjects
Animals, Ecosystem, Bivalvia physiology, Predatory Behavior physiology, Food Chain
Abstract

Predation is a dominant structuring force in ecological communities. In aquatic environments, predation on bivalves has long been an important focal interaction for ecological study because bivalves have central roles as ecosystem engineers, basal components of food webs, and commercial commodities. Studies of bivalves are common, not only because of bivalves' central roles, but also due to the relative ease of studying predatory effects on this taxonomic group. To understand patterns in the interactions of bivalves and their predators we synthesised data from 52 years of peer-reviewed studies on bivalve predation. Using a systematic search, we compiled 1334 studies from 75 countries, comprising 61 bivalve families (N = 2259), dominated by Mytilidae (29% of bivalves), Veneridae (14%), Ostreidae (8%), Unionidae (7%), and Dreissenidae and Tellinidae (6% each). A total of 2036 predators were studied, with crustaceans the most studied predator group (34% of predators), followed by fishes (24%), molluscs (17%), echinoderms (10%) and birds (6%). The majority of studies (86%) were conducted in marine systems, in part driven by the high commercial value of marine bivalves. Studies in freshwater ecosystems were dominated by non-native bivalves and non-native predator species, which probably reflects the important role of biological invasions affecting freshwater biodiversity. In fact, while 81% of the studied marine bivalve species were native, only 50% of the freshwater species were native to the system. In terms of approach, most studies used predation trials, visual analysis of digested contents and exclusion experiments to assess the effects of predation. These studies reflect that many factors influence bivalve predation depending on the species studied, including (i) species traits (e.g. behaviour, morphology, defence mechanisms), (ii) other biotic interactions (e.g. presence of competitors, parasites or diseases), and (iii) environmental context (e.g. temperature, current velocity, beach exposure, habitat complexity). There is a lack of research on the effects of bivalve predation at the population and community and ecosystem levels (only 7% and 0.5% of studies respectively examined impacts at these levels). At the population level, the available studies demonstrate that predation can decrease bivalve density through consumption or the reduction of recruitment. At the community and ecosystem level, predation can trigger effects that cascade through trophic levels or effects that alter the ecological functions bivalves perform. Given the conservation and commercial importance of many bivalve species, studies of predation should be pursued in the context of global change, particularly climate change, acidification and biological invasions., (© 2024 Cambridge Philosophical Society.)

Published
2024
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39. Factors affecting ammonium uptake in streams - an Inter.-biome perspective

Author

Webster, J. R., Mulholland, P. J., Tank, J. L., Valett, H. M., Dodds, W. K., Peterson, B. J., Bowden, W. B., Dahm, Clifford N., Findaly, S., Gregory, S. V., Grimm, N. B., Hamilton, S. K., Johnson, S. L., Martí, Eugènia, McDowell, W. H., Meyer, J. L., Morrall, D. D., Thomas, S. A., and Wollheim, W. M.

Subjects
Metabolism, Nitrogen, Biome, Transient storage, Stable isotope
Abstract

24 Páginas ; 10 Figuras ; 4 Tablas, 1. The Lotic Intersite Nitrogen eXperiment (LINX) was a coordinated study of the relationships between North American biomes and factors governing ammonium uptake in streams. Our objective was to relate inter-biome variability of ammonium uptake to physical, chemical and biological processes. 2. Data were collected from 11 streams ranging from arctic to tropical and from desert to rainforest. Measurements at each site included physical, hydraulic and chemical characteristics, biological parameters, whole-stream metabolism and ammonium uptake. Ammonium uptake was measured by injection of 15N-ammonium and downstream measurements of 15N-ammonium concentration. 3. We found no general, statistically significant relationships that explained the variability in ammonium uptake among sites. However, this approach does not account for the multiple mechanisms of ammonium uptake in streams. When we estimated biological demand for inorganic nitrogen based on our measurements of in-stream metabolism, we found good correspondence between calculated nitrogen demand and measured assimilative nitrogen uptake. 4. Nitrogen uptake varied little among sites, reflecting metabolic compensation in streams in a variety of distinctly different biomes (autotrophic production is high where allochthonous inputs are relatively low and vice versa). 5. Both autotrophic and heterotrophic metabolism require nitrogen and these biotic processes dominate inorganic nitrogen retention in streams. Factors that affect the relative balance of autotrophic and heterotrophic metabolism indirectly control inorganic nitrogen uptake., The LINX study was funded by a grant (DEB-9628860) from the National Science Foundation. Work in Alaska was also funded by the National Science Foundation (OPP-9615949), and the East Fork Little Miami River study was supported by Procter & Gamble. Work at several streams was made possible by collaboration with the U.S. Forest Service and NSF funded LTER studies. Work at Walker Branch, Tennessee, was also partially supported by the Walker Branch Watershed project, Environmental Sciences Division, Office of Biological and Environmental Research, U.S. Department of Energy under contract DE-AC05-00OR22725 with UT-Battelle, LLC.

Published
2003

40. Control of nitrogen export from watersheds by headwater streams

Author

Peterson, B. J., Wolheim, W., Mulholland, P. J., Webster, J. R., Meyer, J. L., Tank, J. L., Grimm, N. B., Martí, Eugènia, Bowden, W. B., Vallet, H. M., Hershey, A. E., McDowell, W. B., Dodds, W. K., Hamilton, S. K., Gregory, S., and D'Angelo, D. J.

Subjects
Geologic Sediments, Nitrogen, chemistry.chemical_element, Fresh Water, STREAMS, Absorption, chemistry.chemical_compound, Nutrient, Nitrate, Animals, Ammonium, Photosynthesis, Ecosystem, Hydrology, geography, Multidisciplinary, geography.geographical_feature_category, Nitrates, Bacteria, Ecology, Fungi, Eukaryota, Estuary, Stream metabolism, United States, Quaternary Ammonium Compounds, chemistry, Biofilms, Nitrification, Seasons, Oxidation-Reduction
Abstract

5 páginas ; 5 Figuras, A comparative 15N-tracer study of nitrogen dynamics in headwater streams from biomes throughout North America demonstrates that streams exert control over nutrient exports to rivers, lakes, and estuaries. The most rapid uptake and transformation of inorganic nitrogen occurred in the smallest streams. Ammonium entering these streams was removed from the water within a few tens to hundreds of meters. Nitrate was also removed from stream water but traveled a distance 5 to 10 times as long, on average, as ammonium. Despite low ammonium concentration in stream water, nitrification rates were high, indicating that small streams are potentially important sources of atmospheric nitrous oxide. During seasons of high biological activity, the reaches of headwater streams typically export downstream less than half of the input of dissolved inorganic nitrogen from their watersheds., NSF grants DEB-9628860, DEB-9810222, and OPP-9615949

Published
2001

41. Dissolved organic matter sources in large Arctic rivers

Author

Amon, R. M. W., Rinehart, A. J., Duan, S., Louchouarn, P., Prokushkin, A., Guggenberger, G., Bauch, Dorothea, Stedmon, C., Raymond, P. A., Holmes, R. M., McClelland, J. W., Peterson, B. J., Walker, S. A., Zhulidov, A. V., Amon, R. M. W., Rinehart, A. J., Duan, S., Louchouarn, P., Prokushkin, A., Guggenberger, G., Bauch, Dorothea, Stedmon, C., Raymond, P. A., Holmes, R. M., McClelland, J. W., Peterson, B. J., Walker, S. A., and Zhulidov, A. V.

Abstract

The biomarker composition of dissolved organic carbon (DOC) of the six largest Arctic rivers was studied between 2003 and 2007 as part of the PARTNERS Project. Samples were collected over seasonal cycles relatively close to the river mouths. Here we report the lignin phenol and p-hydroxybenzene composition of Arctic river DOC in order to identify major sources of carbon. Arctic river DOC represents an important carbon conduit linking the large pools of organic carbon in the Arctic/Subarctic watersheds to the Arctic Ocean. Most of the annual lignin discharge (>75%) occurs during the two month of spring freshet with extremely high lignin concentrations and a lignin phenol composition indicative of fresh vegetation from boreal forests. The three large Siberian rivers, Lena, Yenisei, and Ob, which also have the highest proportion of forests within their watersheds, contribute about 90% of the total lignin discharge to the Arctic Ocean. The composition of river DOC is also characterized by elevated levels of p-hydroxybenzenes, particularly during the low flow season, which indicates a larger contribution from mosses and peat bogs. The lignin composition was strongly related to the average 14C-age of DOC supporting the abundance of young, boreal-vegetation-derived leachates during spring flood, and older, soil-, peat-, and wetland-derived DOC during groundwater dominated low flow conditions, particularly in the Ob and Yukon Rivers. We observed significant differences in DOC concentration and composition between the rivers over the seasonal cycles with the Mackenzie River being the most unique, the Lena River being similar to the Yenisei, and the Yukon being most similar to the Ob. The observed relationship between the lignin phenol composition and watershed characteristics suggests that DOC discharge from these rivers could increase in a warmer climate under otherwise undisturbed conditions.

Published
2012
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42. Development of net-current free heliotron plasmas in the Large Helical Device

Author

Komori, A., Yamada, H., Sakakibara, S., Kaneko, O., Kawahata, K., Mutoh, T., Ohyabu, N., Imagawa, S., Ida, K., Nagayama, Y., Shimozuma, T., Watanabe, K. Y., Mito, T., Kobayashi, M., Nagaoka, K., Sakamoto, R., Yoshida, N., Ohdachi, S., Ashikawa, N., Feng, Y., Fukuda, T., Igami, H., Inagaki, S., Kasahara, H., Kubo, S., Kumazawa, R., Mitarai, O., Murakami, S., Nakamura, Yuji, Nishiura, M., Hino, T., Masuzaki, S., Tanaka, K., Toi, K., Weller, A., Yoshinuma, M., Narushima, Y., Ohno, N., Okamura, T., Tamura, N., Saito, K., Seki, T., Sudo, S., Tanaka, H., Tokuzawa, T., Yanagi, N., Yokoyama, M., Yoshimura, Y., Akiyama, T., Chikaraishi, H., Chowdhuri, M., Emoto, M., Ezumi, N., Funaba, H., Garcia, L., Goncharov, P., Goto, M., Ichiguchi, K., Ichimura, M., Idei, H., Ido, T., Iio, S., Ikeda, K., Irie, M., Isayama, A., Ishigooka, T., Isobe, M., Ito, T., Itoh, K., Iwamae, A., Hamaguchi, S., Hamajima, T., Kitajima, S., Kado, S., Kato, D., Kato, T., Kobayashi, S., Kondo, K., Masamune, S., Matsumoto, Y., Matsunami, N., Minami, T., Michael, C., Miura, H., Miyazawa, J., Mizuguchi, N., Morisaki, T., Morita, S., Motojima, G., Murakami, I., Muto, S., Nagasaki, K., Nakajima, N., Nakamura, Y., Nakanishi, H., Nakano, H., Narihara, K., Nishimura, A., Nishimura, H., Nishimura, K., Nishimura, S., Nishino, N., Notake, T., Obana, T., Ogawa, K., Oka, Y., Ohishi, T., Okada, H., Okuno, K., Ono, K., Osakabe, M., Osako, T., Ozaki, T., Peterson, B. J., Sakaue, H., Sasao, M., Satake, S., Sato, K., Sato, M., Shimizu, A., Shiratani, M., Shoji, M., Sugama, H., Suzuki, C., Suzuki, Y., Takahata, K., Takahashi, H., Takase, Y., Takeiri, Y., Takenaga, H., Toda, S., Todo, Y., Tokitani, M., Tsuchiya, H., Tsumori, K., Urano, H., Veshchev, E., Watanabe, F., Watanabe, T., Watanabe, T. H., Yamada, I., Yamada, S., Yamagishi, O., Yamaguchi, S., Yoshimura, S., Yoshinaga, T., Motojima, O., Komori, A., Yamada, H., Sakakibara, S., Kaneko, O., Kawahata, K., Mutoh, T., Ohyabu, N., Imagawa, S., Ida, K., Nagayama, Y., Shimozuma, T., Watanabe, K. Y., Mito, T., Kobayashi, M., Nagaoka, K., Sakamoto, R., Yoshida, N., Ohdachi, S., Ashikawa, N., Feng, Y., Fukuda, T., Igami, H., Inagaki, S., Kasahara, H., Kubo, S., Kumazawa, R., Mitarai, O., Murakami, S., Nakamura, Yuji, Nishiura, M., Hino, T., Masuzaki, S., Tanaka, K., Toi, K., Weller, A., Yoshinuma, M., Narushima, Y., Ohno, N., Okamura, T., Tamura, N., Saito, K., Seki, T., Sudo, S., Tanaka, H., Tokuzawa, T., Yanagi, N., Yokoyama, M., Yoshimura, Y., Akiyama, T., Chikaraishi, H., Chowdhuri, M., Emoto, M., Ezumi, N., Funaba, H., Garcia, L., Goncharov, P., Goto, M., Ichiguchi, K., Ichimura, M., Idei, H., Ido, T., Iio, S., Ikeda, K., Irie, M., Isayama, A., Ishigooka, T., Isobe, M., Ito, T., Itoh, K., Iwamae, A., Hamaguchi, S., Hamajima, T., Kitajima, S., Kado, S., Kato, D., Kato, T., Kobayashi, S., Kondo, K., Masamune, S., Matsumoto, Y., Matsunami, N., Minami, T., Michael, C., Miura, H., Miyazawa, J., Mizuguchi, N., Morisaki, T., Morita, S., Motojima, G., Murakami, I., Muto, S., Nagasaki, K., Nakajima, N., Nakamura, Y., Nakanishi, H., Nakano, H., Narihara, K., Nishimura, A., Nishimura, H., Nishimura, K., Nishimura, S., Nishino, N., Notake, T., Obana, T., Ogawa, K., Oka, Y., Ohishi, T., Okada, H., Okuno, K., Ono, K., Osakabe, M., Osako, T., Ozaki, T., Peterson, B. J., Sakaue, H., Sasao, M., Satake, S., Sato, K., Sato, M., Shimizu, A., Shiratani, M., Shoji, M., Sugama, H., Suzuki, C., Suzuki, Y., Takahata, K., Takahashi, H., Takase, Y., Takeiri, Y., Takenaga, H., Toda, S., Todo, Y., Tokitani, M., Tsuchiya, H., Tsumori, K., Urano, H., Veshchev, E., Watanabe, F., Watanabe, T., Watanabe, T. H., Yamada, I., Yamada, S., Yamagishi, O., Yamaguchi, S., Yoshimura, S., Yoshinaga, T., and Motojima, O.

Published
2009

43. Development of net-current free heliotron plasmas in the Large Helical Device

Author

20198245, 20237506, 50169116, Komori, A., Yamada, H., Sakakibara, S., Kaneko, O., Kawahata, K., Mutoh, T., Ohyabu, N., Imagawa, S., Ida, K., Nagayama, Y., Shimozuma, T., Watanabe, K. Y., Mito, T., Kobayashi, M., Nagaoka, K., Sakamoto, R., Yoshida, N., Ohdachi, S., Ashikawa, N., Feng, Y., Fukuda, T., Igami, H., Inagaki, S., Kasahara, H., Kubo, S., Kumazawa, R., Mitarai, O., Murakami, S., Nakamura, Yuji, Nishiura, M., Hino, T., Masuzaki, S., Tanaka, K., Toi, K., Weller, A., Yoshinuma, M., Narushima, Y., Ohno, N., Okamura, T., Tamura, N., Saito, K., Seki, T., Sudo, S., Tanaka, H., Tokuzawa, T., Yanagi, N., Yokoyama, M., Yoshimura, Y., Akiyama, T., Chikaraishi, H., Chowdhuri, M., Emoto, M., Ezumi, N., Funaba, H., Garcia, L., Goncharov, P., Goto, M., Ichiguchi, K., Ichimura, M., Idei, H., Ido, T., Iio, S., Ikeda, K., Irie, M., Isayama, A., Ishigooka, T., Isobe, M., Ito, T., Itoh, K., Iwamae, A., Hamaguchi, S., Hamajima, T., Kitajima, S., Kado, S., Kato, D., Kato, T., Kobayashi, S., Kondo, K., Masamune, S., Matsumoto, Y., Matsunami, N., Minami, T., Michael, C., Miura, H., Miyazawa, J., Mizuguchi, N., Morisaki, T., Morita, S., Motojima, G., Murakami, I., Muto, S., Nagasaki, K., Nakajima, N., Nakamura, Y., Nakanishi, H., Nakano, H., Narihara, K., Nishimura, A., Nishimura, H., Nishimura, K., Nishimura, S., Nishino, N., Notake, T., Obana, T., Ogawa, K., Oka, Y., Ohishi, T., Okada, H., Okuno, K., Ono, K., Osakabe, M., Osako, T., Ozaki, T., Peterson, B. J., Sakaue, H., Sasao, M., Satake, S., Sato, K., Sato, M., Shimizu, A., Shiratani, M., Shoji, M., Sugama, H., Suzuki, C., Suzuki, Y., Takahata, K., Takahashi, H., Takase, Y., Takeiri, Y., Takenaga, H., Toda, S., Todo, Y., Tokitani, M., Tsuchiya, H., Tsumori, K., Urano, H., Veshchev, E., Watanabe, F., Watanabe, T., Watanabe, T. H., Yamada, I., Yamada, S., Yamagishi, O., Yamaguchi, S., Yoshimura, S., Yoshinaga, T., Motojima, O., 20198245, 20237506, 50169116, Komori, A., Yamada, H., Sakakibara, S., Kaneko, O., Kawahata, K., Mutoh, T., Ohyabu, N., Imagawa, S., Ida, K., Nagayama, Y., Shimozuma, T., Watanabe, K. Y., Mito, T., Kobayashi, M., Nagaoka, K., Sakamoto, R., Yoshida, N., Ohdachi, S., Ashikawa, N., Feng, Y., Fukuda, T., Igami, H., Inagaki, S., Kasahara, H., Kubo, S., Kumazawa, R., Mitarai, O., Murakami, S., Nakamura, Yuji, Nishiura, M., Hino, T., Masuzaki, S., Tanaka, K., Toi, K., Weller, A., Yoshinuma, M., Narushima, Y., Ohno, N., Okamura, T., Tamura, N., Saito, K., Seki, T., Sudo, S., Tanaka, H., Tokuzawa, T., Yanagi, N., Yokoyama, M., Yoshimura, Y., Akiyama, T., Chikaraishi, H., Chowdhuri, M., Emoto, M., Ezumi, N., Funaba, H., Garcia, L., Goncharov, P., Goto, M., Ichiguchi, K., Ichimura, M., Idei, H., Ido, T., Iio, S., Ikeda, K., Irie, M., Isayama, A., Ishigooka, T., Isobe, M., Ito, T., Itoh, K., Iwamae, A., Hamaguchi, S., Hamajima, T., Kitajima, S., Kado, S., Kato, D., Kato, T., Kobayashi, S., Kondo, K., Masamune, S., Matsumoto, Y., Matsunami, N., Minami, T., Michael, C., Miura, H., Miyazawa, J., Mizuguchi, N., Morisaki, T., Morita, S., Motojima, G., Murakami, I., Muto, S., Nagasaki, K., Nakajima, N., Nakamura, Y., Nakanishi, H., Nakano, H., Narihara, K., Nishimura, A., Nishimura, H., Nishimura, K., Nishimura, S., Nishino, N., Notake, T., Obana, T., Ogawa, K., Oka, Y., Ohishi, T., Okada, H., Okuno, K., Ono, K., Osakabe, M., Osako, T., Ozaki, T., Peterson, B. J., Sakaue, H., Sasao, M., Satake, S., Sato, K., Sato, M., Shimizu, A., Shiratani, M., Shoji, M., Sugama, H., Suzuki, C., Suzuki, Y., Takahata, K., Takahashi, H., Takase, Y., Takeiri, Y., Takenaga, H., Toda, S., Todo, Y., Tokitani, M., Tsuchiya, H., Tsumori, K., Urano, H., Veshchev, E., Watanabe, F., Watanabe, T., Watanabe, T. H., Yamada, I., Yamada, S., Yamagishi, O., Yamaguchi, S., Yoshimura, S., Yoshinaga, T., and Motojima, O.

Published
2009

45. An analysis of the carbon balance of the Arctic Basin from 1997 to 2006 A. D. MCGUIRE ET AL. AN ANALYSIS OF THE CARBON BALANCE OF THE ARCTIC BASIN.

Author

MCGUIRE, A. D., HAYES, D .J ., KICKLIGHTER, D.W., MANIZZA, M., ZHUANG, Q., CHEN, M., FOLLOWS, M. J ., GURNEY, K. R., MCCLELLAND, J .W., MELILLO, J .M., PETERSON, B. J., and PRINN, R. G.

Subjects
CARBON, CARBON dioxide, GREENHOUSE gases, SEA ice
Abstract

This study used several model-based tools to analyse the dynamics of the Arctic Basin between 1997 and 2006 as a linked system of land-ocean-atmosphere C exchange. The analysis estimates that terrestrial areas of the Arctic Basin lost 62.9 Tg C yr and that the Arctic Ocean gained 94.1 Tg C yr. Arctic lands and oceans were a net CO sink of 108.9 Tg C yr, which is within the range of uncertainty in estimates from atmospheric inversions. Although both lands and oceans of the Arctic were estimated to be CO sinks, the land sink diminished in strength because of increased fire disturbance compared to previous decades, while the ocean sink increased in strength because of increased biological pump activity associated with reduced sea ice cover. Terrestrial areas of the Arctic were a net source of 41.5 Tg CH yr that increased by 0.6 Tg CH yr during the decade of analysis, a magnitude that is comparable with an atmospheric inversion of CH. Because the radiative forcing of the estimated CH emissions is much greater than the CO sink, the analysis suggests that the Arctic Basin is a substantial net source of green house gas forcing to the climate system. [ABSTRACT FROM AUTHOR]

Published
2010
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48. Flux and age of dissolved organic carbon exported to the Arctic Ocean: A carbon isotopic study of the five largest arctic rivers.

Author

Raymond, Peter A., McCleland, J. W., Holmes, R. M., Zhulidov, A. V., Mull, K., Peterson, B. J., Striegl, R. G., Aiken, G. R., and Gurtovaya, T. Y.

Subjects
GROUNDWATER flow, INTERNATIONAL trade, AEROSOLS, ATOMIZATION, FLUID dynamics, SALINE waters, LEACHING, SEAWATER
Abstract

The export and Δ14C-age of dissolved organic carbon (DOC) was determined for the Yenisey, Lena, Ob', Mackenzie, and Yukon rivers for 2004-2005. Concentrations of DOC elevate significantly with increasing discharge in these rivers, causing approximately 60% of the annual export to occur during a 2-month period following spring ice breakup. We present a total annual flux from the five rivers of 16 teragrams (Tg), and conservatively estimate that the total input of DOC to the Arctic Ocean is 25-36 Tg, which is ~5-20% greater than previous fluxes. These fluxes are also ~2.5 x greater than temperate rivers with similar watershed sizes and water discharge. Δ14C-DOC shows a clear relationship with hydrology. A small pool of DOC slightly depleted in Δ14C is exported with base flow. The large pool extorted with spring thaw is enriched in Δ14C with respect to current-day atmospheric Δ14C-CO2 values. A simple model predicts that ~50% of DOC exported during the arctic spring thaw is 1-5 years old, ~25% is 6-10 years in age, and 15% is 11-20 years old. The dominant spring melt period, a historically undersampled period, exports a large amount of young and presumably semilabile DOC to the Arctic Ocean. [ABSTRACT FROM AUTHOR]

Published
2007
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50. Food web interactions along seagrass–coral reef boundaries: Effects of piscivore reductions on cross-habitat energy exchange

Author

Valentine, J. F., Valentine, J. F., Heck Jr., K. L., Blackmon, D., Goecker, M. E., Christian, J., Kroutil, R. M., Kirsch, K. D., Peterson, B. J., Beck, M., Vanderklift, Mathew A., Valentine, J. F., Valentine, J. F., Heck Jr., K. L., Blackmon, D., Goecker, M. E., Christian, J., Kroutil, R. M., Kirsch, K. D., Peterson, B. J., Beck, M., and Vanderklift, Mathew A.

Abstract

Although early studies qualitatively documented the importance of cross-habitat energy transfers from seagrasses to coral reefs, such exchanges have yet to be quantified. Empirical evidence suggests that grazing by reef-associated herbivores along the coral reef–seagrass interface can be intense (e.g. conspicuous presence of bare-sand ‘halos’ surrounding coral reefs). This evidence must be interpreted with caution, however, as most of it comes from areas that have experienced sustained, intense overfishing. To quantify the impacts of piscivore removal on cross-habitat energy exchange at the coral reef–seagrass interface, we compared grazing intensity along fished and no-take reefs in the upper and lower Florida Keys. Using visual census techniques and direct measures of seagrass grazing, we documented the impacts of piscivore density on herbivory along the seagrass–coral reef interface. Grazing rates were greater than observed seagrass (Thalassia testudinum) production near reefs in the upper Keys, but less than 48% of production in the lower Keys. Analyses showed that these large differences were not related to regional differences in either herbivore density or species composition. Seagrass biomass was also lower near reefs in the upper Keys, where estimates of grazing were highest. Piscivores were dominated by transient predators (jacks and barracudas) whose densities varied with region and distance from reef, but not with protection from fishing. A nonsignificant negative correlation between great barracuda density and leaf losses from tethered shoots, coupled with the greater abundances of larger grazers near reefs, suggests that predation risk, rather than direct reductions in density, may limit grazers to intense feeding on seagrasses adjacent to reefs in the upper Keys. The large-scale variation in grazing intensity illustrates the need for more detailed quantifications of energy exchanges along the seagrass–coral reef boundary.

Published
2007

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