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Yamada K, Bixler B, Sakurai Y, Ashton PC, Sugiyama J, Arnold K, Begin J, Corbett L, Day-Weiss S, Galitzki N, Hill CA, Johnson BR, Jost B, Kusaka A, Koopman BJ, Lashner J, Lee AT, Mangu A, Nishino H, Page LA, Randall MJ, Sasaki D, Song X, Spisak J, Tsan T, Wang Y, Williams PA. The Simons Observatory: Cryogenic half wave plate rotation mechanism for the small aperture telescopes. Rev Sci Instrum 2024; 95:024504. [PMID: 38385955 DOI: 10.1063/5.0178066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Accepted: 02/01/2024] [Indexed: 02/23/2024]
Abstract
We present the requirements, design, and evaluation of the cryogenic continuously rotating half-wave plate (CHWP) for the Simons Observatory (SO). SO is a cosmic microwave background polarization experiment at Parque Astronómico de Atacama in northern Chile that covers a wide range of angular scales using both small (⌀0.42 m) and large (⌀6 m) aperture telescopes. In particular, the small aperture telescopes (SATs) focus on large angular scales for primordial B-mode polarization. To this end, the SATs employ a CHWP to modulate the polarization of the incident light at 8 Hz, suppressing atmospheric 1/f noise and mitigating systematic uncertainties that would otherwise arise due to the differential response of detectors sensitive to orthogonal polarizations. The CHWP consists of a 505 mm diameter achromatic sapphire HWP and a cryogenic rotation mechanism, both of which are cooled down to ∼50 K to reduce detector thermal loading. Under normal operation, the HWP is suspended by a superconducting magnetic bearing and rotates with a constant 2 Hz frequency, controlled by an electromagnetic synchronous motor. We find that the number of superconductors and the number of magnets that make up the superconducting magnetic bearing are important design parameters, especially for the rotation mechanism's vibration performance. The rotation angle is detected through an angular encoder with a noise level of 0.07 μrad s. During a cooldown process, the rotor is held in place by a grip-and-release mechanism that serves as both an alignment device and a thermal path. In this paper, we provide an overview of the SO SAT CHWP: its requirements, hardware design, and laboratory performance.
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Affiliation(s)
- K Yamada
- Department of Physics, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan
| | - B Bixler
- Department of Physics, University of California, San Diego, La Jolla, California 92093, USA
| | - Y Sakurai
- Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
- Kavli Institute for the Physics and Mathematics of the Universe (WPI), UTIAS, The University of Tokyo, Chiba 277-8583, Japan
| | - P C Ashton
- Kavli Institute for the Physics and Mathematics of the Universe (WPI), UTIAS, The University of Tokyo, Chiba 277-8583, Japan
- Physics Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Department of Physics, University of California, Berkeley, California 94720, USA
| | - J Sugiyama
- Department of Physics, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan
| | - K Arnold
- Department of Physics, University of California, San Diego, La Jolla, California 92093, USA
| | - J Begin
- Joseph Henry Laboratories of Physics, Jadwin Hall, Princeton University, Princeton, New Jersey 08544, USA
| | - L Corbett
- Physics Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Department of Physics, University of California, Berkeley, California 94720, USA
| | - S Day-Weiss
- Joseph Henry Laboratories of Physics, Jadwin Hall, Princeton University, Princeton, New Jersey 08544, USA
| | - N Galitzki
- Department of Physics, University of Texas at Austin, Austin, Texas 78722, USA
- Weinberg Institute for Theoretical Physics, Texas Center for Cosmology and Astroparticle Physics, Austin, Texas 78712, USA
| | - C A Hill
- Physics Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Department of Physics, University of California, Berkeley, California 94720, USA
| | - B R Johnson
- Department of Astronomy, University of Virginia, Charlottesville, Virginia 22904, USA
| | - B Jost
- Kavli Institute for the Physics and Mathematics of the Universe (WPI), UTIAS, The University of Tokyo, Chiba 277-8583, Japan
| | - A Kusaka
- Department of Physics, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan
- Kavli Institute for the Physics and Mathematics of the Universe (WPI), UTIAS, The University of Tokyo, Chiba 277-8583, Japan
- Physics Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - B J Koopman
- Wright Laboratory, Department of Physics, Yale University, New Haven, Connecticut 06520, USA
| | - J Lashner
- Wright Laboratory, Department of Physics, Yale University, New Haven, Connecticut 06520, USA
| | - A T Lee
- Physics Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Department of Physics, University of California, Berkeley, California 94720, USA
| | - A Mangu
- Department of Physics, University of California, Berkeley, California 94720, USA
| | - H Nishino
- Research Center for the Early Universe, School of Science, The University of Tokyo, Tokyo 113-0033, Japan
| | - L A Page
- Joseph Henry Laboratories of Physics, Jadwin Hall, Princeton University, Princeton, New Jersey 08544, USA
| | - M J Randall
- Department of Physics, University of California, San Diego, La Jolla, California 92093, USA
| | - D Sasaki
- Department of Physics, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan
| | - X Song
- Department of Physics, University of California, Berkeley, California 94720, USA
| | - J Spisak
- Department of Physics, University of California, San Diego, La Jolla, California 92093, USA
| | - T Tsan
- Department of Physics, University of California, San Diego, La Jolla, California 92093, USA
| | - Y Wang
- Joseph Henry Laboratories of Physics, Jadwin Hall, Princeton University, Princeton, New Jersey 08544, USA
| | - P A Williams
- Physics Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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Shroyer JE, Nelson M, Walters L, Johnson BR. A scalable cryogenic LED module for selectively illuminating kinetic inductance detector arrays. Rev Sci Instrum 2022; 93:113107. [PMID: 36461559 DOI: 10.1063/5.0103968] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Accepted: 10/30/2022] [Indexed: 06/17/2023]
Abstract
We present the design and measured performance of a light emitting diode (LED) module for spatially mapping kinetic inductance detector (KID) arrays in the laboratory. Our novel approach uses a multiplexing scheme that only requires seven wires to control 480 red LEDs, and the number of LEDs can be scaled up without adding any additional wires. This multiplexing approach relies on active surface mount components that can operate at cryogenic temperatures down to 10 K. Cryogenic tests in liquid nitrogen and inside our cryostat demonstrate that the multiplexer circuit works at 77 and 10 K, respectively. The LED module presented here is tailored for our millimeter-wave detector modules, but the approach could be adapted for use with other KID-based detector systems.
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Affiliation(s)
- J E Shroyer
- Department of Astronomy, University of Virginia, Charlottesville, Virginia 22904, USA
| | - M Nelson
- Department of Astronomy, University of Virginia, Charlottesville, Virginia 22904, USA
| | - L Walters
- Department of Astronomy, University of Virginia, Charlottesville, Virginia 22904, USA
| | - B R Johnson
- Department of Astronomy, University of Virginia, Charlottesville, Virginia 22904, USA
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Brambila A, Reed PB, Bridgham SD, Roy BA, Johnson BR, Pfeifer‐Meister L, Hallett LM. Disturbance: a double‐edged sword for restoration in a changing climate. Restor Ecol 2022. [DOI: 10.1111/rec.13675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | - Paul B. Reed
- Institute of Ecology and Evolution University of Oregon
| | | | - Bitty A. Roy
- Institute of Ecology and Evolution University of Oregon
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Reed PB, Pfeifer‐Meister LE, Roy BA, Johnson BR, Bailes GT, Nelson AA, Bridgham SD. Introduced annuals mediate climate‐driven community change in Mediterranean prairies of the Pacific Northwest, USA. DIVERS DISTRIB 2021. [DOI: 10.1111/ddi.13426] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Affiliation(s)
- Paul B. Reed
- Institute of Ecology and Evolution University of Oregon Eugene OR USA
| | | | - Bitty A. Roy
- Institute of Ecology and Evolution University of Oregon Eugene OR USA
| | - Bart R. Johnson
- Department of Landscape Architecture University of Oregon Eugene OR USA
| | - Graham T. Bailes
- Institute of Ecology and Evolution University of Oregon Eugene OR USA
| | - Aaron A. Nelson
- Institute of Ecology and Evolution University of Oregon Eugene OR USA
| | - Scott D. Bridgham
- Institute of Ecology and Evolution University of Oregon Eugene OR USA
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Mhuireach GÁ, Wilson H, Johnson BR. Urban Aerobiomes are Influenced by Season, Vegetation, and Individual Site Characteristics. Ecohealth 2021; 18:331-344. [PMID: 33170406 DOI: 10.1007/s10393-020-01493-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 10/02/2020] [Accepted: 10/04/2020] [Indexed: 06/11/2023]
Abstract
Exposure to biodiverse environments such as forests can benefit human well-being, and evidence suggests exposure to high microbial diversity may improve mental and immune health. However, the factors that drive microbial community assembly are poorly understood, as is the relationship between exposure to these communities and human health. We characterized airborne bacterial communities in two disparate types of urban greenspace (forest and grass) in late-spring 2017 at sites previously sampled in late-summer 2015 in Eugene-Springfield, Oregon, using high-throughput metabarcode sequencing. While all sites shared a core aerobiome in late-spring consisting of plant- and soil-associated genera, forests had significantly higher diversity than grass sites (F = 12, P = 0.004). Vegetation type explained 14% of the difference between forest and grass aerobiomes, yet individual site location explained 41% of the variation. These results were similar to but amplified over those from late summer, suggesting that both aerobiome diversity and vegetation-driven effects are higher when deciduous foliage is fresher and more active, temperatures cooler, and humidity higher. Continued exploration and hypothesis-driven research will enable development of mechanistic theory describing key drivers of urban aerobiome assembly and its relationship to human health, which, in turn, will help urban designers and planners create evidence-based salutogenic cities for future generations.
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Affiliation(s)
- Gwynne Á Mhuireach
- Department of Landscape Architecture, University of Oregon, 5250 University of Oregon, Eugene, OR, 97403, USA.
- Biology and the Built Environment (BioBE) Center, University of Oregon, Eugene, OR, USA.
- Institute for Health in the Built Environment, University of Oregon, Eugene, OR, USA.
| | - Hannah Wilson
- Biology and the Built Environment (BioBE) Center, University of Oregon, Eugene, OR, USA
- Division of Plant Sciences, University of Missouri, Columbia, MO, USA
| | - Bart R Johnson
- Department of Landscape Architecture, University of Oregon, 5250 University of Oregon, Eugene, OR, 97403, USA
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Reed PB, Bridgham SD, Pfeifer-Meister LE, Peterson ML, Johnson BR, Roy BA, Bailes GT, Nelson AA, Morris WF, Doak DF. Climate warming threatens the persistence of a community of disturbance-adapted native annual plants. Ecology 2021; 102:e03464. [PMID: 34236709 DOI: 10.1002/ecy.3464] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Revised: 03/29/2021] [Accepted: 05/13/2021] [Indexed: 01/15/2023]
Abstract
With ongoing climate change, populations are expected to exhibit shifts in demographic performance that will alter where a species can persist. This presents unique challenges for managing plant populations and may require ongoing interventions, including in situ management or introduction into new locations. However, few studies have examined how climate change may affect plant demographic performance for a suite of species, or how effective management actions could be in mitigating climate change effects. Over the course of two experiments spanning 6 yr and four sites across a latitudinal gradient in the Pacific Northwest, United States, we manipulated temperature, precipitation, and disturbance intensity, and quantified effects on the demography of eight native annual prairie species. Each year we planted seeds and monitored germination, survival, and reproduction. We found that disturbance strongly influenced demographic performance and that seven of the eight species had increasingly poor performance with warmer conditions. Across species and sites, we observed 11% recruitment (the proportion of seeds planted that survived to reproduction) following high disturbance, but just 3.9% and 2.3% under intermediate and low disturbance, respectively. Moreover, mean seed production following high disturbance was often more than tenfold greater than under intermediate and low disturbance. Importantly, most species exhibited precipitous declines in their population growth rates (λ) under warmer-than-ambient experimental conditions and may require more frequent disturbance intervention to sustain populations. Aristida oligantha, a C4 grass, was the only species to have λ increase with warmer conditions. These results suggest that rising temperatures may cause many native annual plant species to decline, highlighting the urgency for adaptive management practices that facilitate their restoration or introduction to newly suitable locations. Frequent and intense disturbances are critical to reduce competitors and promote native annuals' persistence, but even such efforts may prove futile under future climate regimes.
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Affiliation(s)
- Paul B Reed
- Institute of Ecology and Evolution, University of Oregon, Eugene, Oregon, 97403, USA
| | - Scott D Bridgham
- Institute of Ecology and Evolution, University of Oregon, Eugene, Oregon, 97403, USA
| | | | - Megan L Peterson
- Plant Biology Department, University of Georgia, Athens, Georgia, 30606, USA
| | - Bart R Johnson
- Department of Landscape Architecture, University of Oregon, Eugene, Oregon, 97403, USA
| | - Bitty A Roy
- Institute of Ecology and Evolution, University of Oregon, Eugene, Oregon, 97403, USA
| | - Graham T Bailes
- Institute of Ecology and Evolution, University of Oregon, Eugene, Oregon, 97403, USA
| | - Aaron A Nelson
- Institute of Ecology and Evolution, University of Oregon, Eugene, Oregon, 97403, USA
| | - William F Morris
- Biology Department, Duke University, Durham, North Carolina, 27708, USA
| | - Daniel F Doak
- Environmental Studies Program, University of Colorado Boulder, Boulder, Colorado, 80309, USA
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DeMarche ML, Bailes G, Hendricks LB, Pfeifer‐Meister L, Reed PB, Bridgham SD, Johnson BR, Shriver R, Waddle E, Wroton H, Doak DF, Roy BA, Morris WF. Latitudinal gradients in population growth do not reflect demographic responses to climate. Ecol Appl 2021; 31:e2242. [PMID: 33098736 PMCID: PMC7988552 DOI: 10.1002/eap.2242] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 07/03/2020] [Accepted: 07/07/2020] [Indexed: 06/09/2023]
Abstract
Spatial gradients in population growth, such as across latitudinal or elevational gradients, are often assumed to primarily be driven by variation in climate, and are frequently used to infer species' responses to climate change. Here, we use a novel demographic, mixed-model approach to dissect the contributions of climate variables vs. other latitudinal or local site effects on spatiotemporal variation in population performance in three perennial bunchgrasses. For all three species, we find that performance of local populations decreases with warmer and drier conditions, despite latitudinal trends of decreasing population growth toward the cooler and wetter northern portion of each species' range. Thus, latitudinal gradients in performance are not predictive of either local or species-wide responses to climate. This pattern could be common, as many environmental drivers, such as habitat quality or species' interactions, are likely to vary with latitude or elevation, and thus influence or oppose climate responses.
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Affiliation(s)
| | - Graham Bailes
- Institute of Ecology and EvolutionUniversity of OregonEugeneOregon97403USA
| | | | | | - Paul B. Reed
- Institute of Ecology and EvolutionUniversity of OregonEugeneOregon97403USA
| | - Scott D. Bridgham
- Institute of Ecology and EvolutionUniversity of OregonEugeneOregon97403USA
| | - Bart R. Johnson
- Department of Landscape ArchitectureUniversity of OregonEugeneOregon97403USA
| | - Robert Shriver
- Department of Natural Resources and Environmental ScienceUniversity of NevadaRenoNevada89557USA
| | - Ellen Waddle
- Environmental Studies ProgramUniversity of Colorado BoulderBoulderColorado80309USA
| | - Hannah Wroton
- Ecology and Evolutionary Biology DepartmentUniversity of Colorado BoulderColorado80309USA
| | - Daniel F. Doak
- Environmental Studies ProgramUniversity of Colorado BoulderBoulderColorado80309USA
| | - Bitty A. Roy
- Institute of Ecology and EvolutionUniversity of OregonEugeneOregon97403USA
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DeMarche ML, Bailes G, Hendricks LB, Pfeifer-Meister L, Reed PB, Bridgham SD, Johnson BR, Shriver R, Waddle E, Wroton H, Doak DF, Roy BA, Morris WF. Latitudinal gradients in population growth do not reflect demographic responses to climate. Ecol Appl 2021. [PMID: 33098736 DOI: 10.5061/dryad.2rbnzs7m0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Spatial gradients in population growth, such as across latitudinal or elevational gradients, are often assumed to primarily be driven by variation in climate, and are frequently used to infer species' responses to climate change. Here, we use a novel demographic, mixed-model approach to dissect the contributions of climate variables vs. other latitudinal or local site effects on spatiotemporal variation in population performance in three perennial bunchgrasses. For all three species, we find that performance of local populations decreases with warmer and drier conditions, despite latitudinal trends of decreasing population growth toward the cooler and wetter northern portion of each species' range. Thus, latitudinal gradients in performance are not predictive of either local or species-wide responses to climate. This pattern could be common, as many environmental drivers, such as habitat quality or species' interactions, are likely to vary with latitude or elevation, and thus influence or oppose climate responses.
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Affiliation(s)
- Megan L DeMarche
- Plant Biology Department, University of Georgia, Athens, Georgia, 30606, USA
| | - Graham Bailes
- Institute of Ecology and Evolution, University of Oregon, Eugene, Oregon, 97403, USA
| | - Lauren B Hendricks
- Department of Geography, University of Oregon, Eugene, Oregon, 97403, USA
| | | | - Paul B Reed
- Institute of Ecology and Evolution, University of Oregon, Eugene, Oregon, 97403, USA
| | - Scott D Bridgham
- Institute of Ecology and Evolution, University of Oregon, Eugene, Oregon, 97403, USA
| | - Bart R Johnson
- Department of Landscape Architecture, University of Oregon, Eugene, Oregon, 97403, USA
| | - Robert Shriver
- Department of Natural Resources and Environmental Science, University of Nevada, Reno, Nevada, 89557, USA
| | - Ellen Waddle
- Environmental Studies Program, University of Colorado Boulder, Boulder, Colorado, 80309, USA
| | - Hannah Wroton
- Ecology and Evolutionary Biology Department, University of Colorado Boulder, Colorado, 80309, USA
| | - Daniel F Doak
- Environmental Studies Program, University of Colorado Boulder, Boulder, Colorado, 80309, USA
| | - Bitty A Roy
- Institute of Ecology and Evolution, University of Oregon, Eugene, Oregon, 97403, USA
| | - William F Morris
- Biology Department, Duke University, Durham, North Carolina, 27710, USA
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Friedman DA, Johnson BR, Linksvayer TA. Distributed physiology and the molecular basis of social life in eusocial insects. Horm Behav 2020; 122:104757. [PMID: 32305342 DOI: 10.1016/j.yhbeh.2020.104757] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 03/30/2020] [Accepted: 04/06/2020] [Indexed: 12/24/2022]
Abstract
The traditional focus of physiological and functional genomic research is on molecular processes that play out within a single multicellular organism. In the colonial (eusocial) insects such as ants, bees, and termites, molecular and behavioral responses of interacting nestmates are tightly linked, and key physiological processes are regulated at the scale of the colony. Such colony-level physiological processes regulate nestmate physiology in a distributed fashion, through various social communication mechanisms. As a result of physiological decentralization over evolutionary time, organismal mechanisms, for example related to pheromone detection, hormone signaling, and neural signaling pathways, are deployed in novel contexts to influence nestmate and colony traits. Here we explore how functional genomic, physiological, and behavioral studies can benefit from considering the traits of eusocial insects in this light. We highlight functional genomic work exploring how nestmate-level and colony-level traits arise and are influenced by interactions among physiologically-specialized nestmates of various developmental stages. We also consider similarities and differences between nestmate-level (organismal) and colony-level (superorganismal) physiological processes, and make specific hypotheses regarding the physiology of eusocial taxa. Integrating theoretical models of distributed systems with empirical functional genomics approaches will be useful in addressing fundamental questions related to the evolution of eusociality and collective behavior in natural systems.
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Affiliation(s)
- D A Friedman
- University of California, Davis, Department of Entomology, Davis, CA 95616, United States of America.
| | - B R Johnson
- University of California, Davis, Department of Entomology, Davis, CA 95616, United States of America
| | - T A Linksvayer
- University of Pennsylvania, Department of Biology, Pennsylvania, PA 19104, United States of America
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Reed PB, Pfeifer‐Meister LE, Roy BA, Johnson BR, Bailes GT, Nelson AA, Boulay MC, Hamman ST, Bridgham SD. Prairie plant phenology driven more by temperature than moisture in climate manipulations across a latitudinal gradient in the Pacific Northwest, USA. Ecol Evol 2019; 9:3637-3650. [PMID: 30962915 PMCID: PMC6434541 DOI: 10.1002/ece3.4995] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 01/26/2019] [Indexed: 01/24/2023] Open
Abstract
Plant phenology will likely shift with climate change, but how temperature and/or moisture regimes will control phenological responses is not well understood. This is particularly true in Mediterranean climate ecosystems where the warmest temperatures and greatest moisture availability are seasonally asynchronous. We examined plant phenological responses at both the population and community levels to four climate treatments (control, warming, drought, and warming plus additional precipitation) embedded within three prairies across a 520 km latitudinal Mediterranean climate gradient within the Pacific Northwest, USA. At the population level, we monitored flowering and abundances in spring 2017 of eight range-restricted focal species planted both within and north of their current ranges. At the community level, we used normalized difference vegetation index (NDVI) measured from fall 2016 to summer 2018 to estimate peak live biomass, senescence, seasonal patterns, and growing season length. We found that warming exerted a stronger control than our moisture manipulations on phenology at both the population and community levels. Warming advanced flowering regardless of whether a species was within or beyond its current range. Importantly, many of our focal species had low abundances, particularly in the south, suggesting that establishment, in addition to phenological shifts, may be a strong constraint on their future viability. At the community level, warming advanced the date of peak biomass regardless of site or year. The date of senescence advanced regardless of year for the southern and central sites but only in 2018 for the northern site. Growing season length contracted due to warming at the southern and central sites (~3 weeks) but was unaffected at the northern site. Our results emphasize that future temperature changes may exert strong influence on the timing of a variety of plant phenological events, especially those events that occur when temperature is most limiting, even in seasonally water-limited Mediterranean ecosystems.
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Affiliation(s)
- Paul B. Reed
- Institute of Ecology and EvolutionUniversity of OregonEugeneOregon
- Environmental Studies ProgramUniversity of OregonEugeneOregon
| | | | - Bitty A. Roy
- Institute of Ecology and EvolutionUniversity of OregonEugeneOregon
| | - Bart R. Johnson
- Department of Landscape ArchitectureUniversity of OregonEugeneOregon
| | - Graham T. Bailes
- Institute of Ecology and EvolutionUniversity of OregonEugeneOregon
| | - Aaron A. Nelson
- Institute of Ecology and EvolutionUniversity of OregonEugeneOregon
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Pfeifer-Meister L, Gayton LG, Roy BA, Johnson BR, Bridgham SD. Greenhouse gas emissions limited by low nitrogen and carbon availability in natural, restored, and agricultural Oregon seasonal wetlands. PeerJ 2018; 6:e5465. [PMID: 30186683 PMCID: PMC6118202 DOI: 10.7717/peerj.5465] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Accepted: 07/27/2018] [Indexed: 11/20/2022] Open
Abstract
Wetlands are the major natural source of the greenhouse gas methane (CH4) and are also potentially an important source of nitrous oxide (N2O), though there is considerable variability among wetland types with some of the greatest uncertainty in freshwater mineral-soil wetlands. In particular, trace gas emissions from seasonal wetlands have been very poorly studied. We measured fluxes of CH4, N2O, and CO2(carbon dioxide), soil nutrients, and net primary productivity over one year in natural, restored, and agricultural seasonal wetland prairies in the Willamette Valley, Oregon, USA. We found zero fluxes for CH4 and N2O, even during periods of extended waterlogging of the soil. To explore this lack of emissions, we performed a laboratory experiment to examine the controls over these gases. In a fully-factorial design, we amended anaerobic soils from all wetlands with nitrate, glucose, and NaOH (to neutralize pH) and measured production potentials of N2, N2O, CH4, and CO2. We found that denitrification and N2O production were co-limited by nitrate and carbon, with little difference between the three wetland types. This co-limitation suggests that low soil carbon availability will continue to constrain N2O emissions and denitrification in these systems even when receiving relatively high levels of nitrogen inputs. Contrary to the results for N2O, the amended wetland soils never produced significant amounts of CH4 under any treatment. We hypothesize that high concentrations of alternative electron acceptors exist in these soils so that methanogens are noncompetitive with other microbial groups. As a result, these wetlands do not appear to be a significant source or sink of soil carbon and thus have a near zero climate forcing effect. Future research should focus on determining if this is a generalizable result in other seasonal wetlands.
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Affiliation(s)
- Laurel Pfeifer-Meister
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR, United States of America
| | - Laura G Gayton
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR, United States of America
| | - Bitty A Roy
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR, United States of America
| | - Bart R Johnson
- Department of Landscape Architecture, University of Oregon, Eugene, OR, United States of America
| | - Scott D Bridgham
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR, United States of America
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Johnson BR, Columbro F, Araujo D, Limon M, Smiley B, Jones G, Reichborn-Kjennerud B, Miller A, Gupta S. A large-diameter hollow-shaft cryogenic motor based on a superconducting magnetic bearing for millimeter-wave polarimetry. Rev Sci Instrum 2017; 88:105102. [PMID: 29092514 DOI: 10.1063/1.4990884] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In this paper, we present the design and measured performance of a novel cryogenic motor based on a superconducting magnetic bearing (SMB). The motor is tailored for use in millimeter-wave half-wave plate (HWP) polarimeters, where a HWP is rapidly rotated in front of a polarization analyzer or polarization-sensitive detector. This polarimetry technique is commonly used in cosmic microwave background polarization studies. The SMB we use is composed of fourteen yttrium barium copper oxide (YBCO) disks and a contiguous neodymium iron boron (NdFeB) ring magnet. The motor is a hollow-shaft motor because the HWP is ultimately installed in the rotor. The motor presented here has a 100 mm diameter rotor aperture. However, the design can be scaled up to rotor aperture diameters of approximately 500 mm. Our motor system is composed of four primary subsystems: (i) the rotor assembly, which includes the NdFeB ring magnet, (ii) the stator assembly, which includes the YBCO disks, (iii) an incremental encoder, and (iv) the drive electronics. While the YBCO is cooling through its superconducting transition, the rotor is held above the stator by a novel hold and release mechanism. The encoder subsystem consists of a custom-built encoder disk read out by two fiber optic readout sensors. For the demonstration described in this paper, we ran the motor at 50 K and tested rotation frequencies up to approximately 10 Hz. The feedback system was able to stabilize the rotation speed to approximately 0.4%, and the measured rotor orientation angle uncertainty is less than 0.15°. Lower temperature operation will require additional development activities, which we will discuss.
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Affiliation(s)
- B R Johnson
- Department of Physics, Columbia University, New York, New York 10027, USA
| | - F Columbro
- Dipartimento di Fisica, Università di Roma La Sapienza, 00185 Roma, Italy
| | - D Araujo
- Department of Physics, Columbia University, New York, New York 10027, USA
| | - M Limon
- Department of Physics, Columbia University, New York, New York 10027, USA
| | - B Smiley
- Department of Physics, Columbia University, New York, New York 10027, USA
| | - G Jones
- Department of Physics, Columbia University, New York, New York 10027, USA
| | | | - A Miller
- Department of Physics and Astronomy, University of Southern California, Los Angeles, California 90089, USA
| | - S Gupta
- Department of Physics, Columbia University, New York, New York 10027, USA
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Roos CI, Scott AC, Belcher CM, Chaloner WG, Aylen J, Bird RB, Coughlan MR, Johnson BR, Johnston FH, McMorrow J, Steelman T. Living on a flammable planet: interdisciplinary, cross-scalar and varied cultural lessons, prospects and challenges. Philos Trans R Soc Lond B Biol Sci 2017; 371:rstb.2015.0469. [PMID: 27216517 DOI: 10.1098/rstb.2015.0469] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/29/2016] [Indexed: 11/12/2022] Open
Abstract
Living with fire is a challenge for human communities because they are influenced by socio-economic, political, ecological and climatic processes at various spatial and temporal scales. Over the course of 2 days, the authors discussed how communities could live with fire challenges at local, national and transnational scales. Exploiting our diverse, international and interdisciplinary expertise, we outline generalizable properties of fire-adaptive communities in varied settings where cultural knowledge of fire is rich and diverse. At the national scale, we discussed policy and management challenges for countries that have diminishing fire knowledge, but for whom global climate change will bring new fire problems. Finally, we assessed major fire challenges that transcend national political boundaries, including the health burden of smoke plumes and the climate consequences of wildfires. It is clear that to best address the broad range of fire problems, a holistic wildfire scholarship must develop common agreement in working terms and build across disciplines. We must also communicate our understanding of fire and its importance to the media, politicians and the general public.This article is part of the themed issue 'The interaction of fire and mankind'.
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Affiliation(s)
- Christopher I Roos
- Department of Anthropology, Southern Methodist University, Dallas, TX 75275, USA
| | - Andrew C Scott
- Department of Earth Sciences, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK
| | - Claire M Belcher
- wildFIRE Lab, Hatherly Laboratories, University of Exeter, Exeter EX4 4PS, UK
| | - William G Chaloner
- Department of Earth Sciences, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK
| | - Jonathan Aylen
- Manchester Business School, University of Manchester, Manchester M13 9PL, UK
| | - Rebecca Bliege Bird
- Department of Anthropology, Pennsylvania State University, University Park, PA 16802, USA
| | - Michael R Coughlan
- Department of Anthropology, University of Georgia, Athens, GA 30602, USA
| | - Bart R Johnson
- Department of Landscape Architecture, University of Oregon, Eugene, OR 97401, USA
| | - Fay H Johnston
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania 7000, Australia
| | - Julia McMorrow
- School of Environment, Education, and Development, University of Manchester, Manchester M13 9PL, UK
| | - Toddi Steelman
- School of Environment and Sustainability, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5C8
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Mhuireach G, Johnson BR, Altrichter AE, Ladau J, Meadow JF, Pollard KS, Green JL. Urban greenness influences airborne bacterial community composition. Sci Total Environ 2016; 571:680-7. [PMID: 27418518 DOI: 10.1016/j.scitotenv.2016.07.037] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Revised: 07/01/2016] [Accepted: 07/06/2016] [Indexed: 05/06/2023]
Abstract
Urban green space provides health benefits for city dwellers, and new evidence suggests that microorganisms associated with soil and vegetation could play a role. While airborne microorganisms are ubiquitous in urban areas, the influence of nearby vegetation on airborne microbial communities remains poorly understood. We examined airborne microbial communities in parks and parking lots in Eugene, Oregon, using high-throughput sequencing of the bacterial 16S rRNA gene on the Illumina MiSeq platform to identify bacterial taxa, and GIS to measure vegetation cover in buffer zones of different diameters. Our goal was to explore variation among highly vegetated (parks) versus non-vegetated (parking lots) urban environments. A secondary objective was to evaluate passive versus active collection methods for outdoor airborne microbial sampling. Airborne bacterial communities from five parks were different from those of five parking lots (p=0.023), although alpha diversity was similar. Direct gradient analysis showed that the proportion of vegetated area within a 50m radius of the sampling station explained 15% of the variation in bacterial community composition. A number of key taxa, including several Acidobacteriaceae were substantially more abundant in parks, while parking lots had higher relative abundance of Acetobacteraceae. Parks had greater beta diversity than parking lots, i.e. individual parks were characterized by unique bacterial signatures, whereas parking lot communities tended to be similar to each other. Although parks and parking lots were selected to form pairs of nearby sites, spatial proximity did not appear to affect compositional similarity. Our results also showed that passive and active collection methods gave comparable results, indicating the "settling dish" method is effective for outdoor airborne sampling. This work sets a foundation for understanding how urban vegetation may impact microbial communities, with potential implications for designing neighborhoods and open space systems that foster better human health.
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Affiliation(s)
- Gwynne Mhuireach
- Department of Landscape Architecture, University of Oregon, Eugene, OR, United States; Institute for a Sustainable Environment, University of Oregon, Eugene, OR, United States; Biology and the Built Environment Center, Institute of Ecology and Evolution, University of Oregon, Eugene, OR, United States; Energy Studies in Buildings Laboratory, Department of Architecture, University of Oregon, Eugene, OR, United States.
| | - Bart R Johnson
- Department of Landscape Architecture, University of Oregon, Eugene, OR, United States; Institute for a Sustainable Environment, University of Oregon, Eugene, OR, United States
| | - Adam E Altrichter
- Biology and the Built Environment Center, Institute of Ecology and Evolution, University of Oregon, Eugene, OR, United States
| | - Joshua Ladau
- Gladstone Institutes, University of California, San Francisco, CA, United States
| | - James F Meadow
- Biology and the Built Environment Center, Institute of Ecology and Evolution, University of Oregon, Eugene, OR, United States
| | - Katherine S Pollard
- Gladstone Institutes, University of California, San Francisco, CA, United States; Division of Biostatistics, Institute for Human Genetics, Institute for Computational Health Sciences, University of California, San Francisco, CA 94158, United States
| | - Jessica L Green
- Biology and the Built Environment Center, Institute of Ecology and Evolution, University of Oregon, Eugene, OR, United States
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Wilson H, Johnson BR, Bohannan B, Pfeifer-Meister L, Mueller R, Bridgham SD. Experimental warming decreases arbuscular mycorrhizal fungal colonization in prairie plants along a Mediterranean climate gradient. PeerJ 2016; 4:e2083. [PMID: 27280074 PMCID: PMC4893335 DOI: 10.7717/peerj.2083] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2016] [Accepted: 05/04/2016] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND Arbuscular mycorrhizal fungi (AMF) provide numerous services to their plant symbionts. Understanding climate change effects on AMF, and the resulting plant responses, is crucial for predicting ecosystem responses at regional and global scales. We investigated how the effects of climate change on AMF-plant symbioses are mediated by soil water availability, soil nutrient availability, and vegetation dynamics. METHODS We used a combination of a greenhouse experiment and a manipulative climate change experiment embedded within a Mediterranean climate gradient in the Pacific Northwest, USA to examine this question. Structural equation modeling (SEM) was used to determine the direct and indirect effects of experimental warming on AMF colonization. RESULTS Warming directly decreased AMF colonization across plant species and across the climate gradient of the study region. Other positive and negative indirect effects of warming, mediated by soil water availability, soil nutrient availability, and vegetation dynamics, canceled each other out. DISCUSSION A warming-induced decrease in AMF colonization would likely have substantial consequences for plant communities and ecosystem function. Moreover, predicted increases in more intense droughts and heavier rains for this region could shift the balance among indirect causal pathways, and either exacerbate or mitigate the negative, direct effect of increased temperature on AMF colonization.
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Affiliation(s)
- Hannah Wilson
- Department of Biology, University of Oregon, Eugene, Oregon, United States
| | - Bart R. Johnson
- Department of Landscape Architecture, University of Oregon, Eugene, Oregon, United States
| | - Brendan Bohannan
- Institute of Ecology and Evolution, University of Oregon, Eugene, Oregon, United States
| | | | - Rebecca Mueller
- Department of Biology, University of Oregon, Eugene, Oregon, United States
| | - Scott D. Bridgham
- Institute of Ecology and Evolution, University of Oregon, Eugene, Oregon, United States
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Ganatra B, Johnson BR. Evidence-based practices can improve safety and timeliness of care for women needing safe termination of pregnancy. BJOG 2016; 123:1692. [PMID: 27146089 DOI: 10.1111/1471-0528.14118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- B Ganatra
- Department of Reproductive Health and Research including UNDP/UNFPA/UNICEF/WHO/World Bank Special Programme of Research, Development and Research Training in Human Reproduction (HRP), World Health Organization, Geneva, Switzerland
| | - B R Johnson
- Department of Reproductive Health and Research including UNDP/UNFPA/UNICEF/WHO/World Bank Special Programme of Research, Development and Research Training in Human Reproduction (HRP), World Health Organization, Geneva, Switzerland
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Vandegrift R, Roy BA, Pfeifer-Meister L, Johnson BR, Bridgham SD. The herbaceous landlord: integrating the effects of symbiont consortia within a single host. PeerJ 2015; 3:e1379. [PMID: 26557442 PMCID: PMC4636405 DOI: 10.7717/peerj.1379] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 10/14/2015] [Indexed: 11/20/2022] Open
Abstract
Plants are typically infected by a consortium of internal fungal associates, including endophytes in their leaves, as well as arbuscular mycorrhizal fungi (AMF) and dark septate endophytes (DSE) in their roots. It is logical that these organisms will interact with each other and the abiotic environment in addition to their host, but there has been little work to date examining the interactions of multiple symbionts within single plant hosts, or how the relationships among symbionts and their host change across environmental conditions. We examined the grass Agrostis capillaris in the context of a climate manipulation experiment in prairies in the Pacific Northwest, USA. Each plant was tested for presence of foliar endophytes in the genus Epichloë, and we measured percent root length colonized (PRLC) by AMF and DSE. We hypothesized that the symbionts in our system would be in competition for host resources, that the outcome of that competition could be driven by the benefit to the host, and that the host plants would be able to allocate carbon to the symbionts in such a way as to maximize fitness benefit within a particular environmental context. We found a correlation between DSE and AMF PRLC across climatic conditions; we also found a fitness cost to increasing DSE colonization, which was negated by presence of Epichloë endophytes. These results suggest that selective pressure on the host is likely to favor host/symbiont relationships that structure the community of symbionts in the most beneficial way possible for the host, not necessarily favoring the individual symbiont that is most beneficial to the host in isolation. These results highlight the need for a more integrative, systems approach to the study of host/symbiont consortia.
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Affiliation(s)
- Roo Vandegrift
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR, United States
| | - Bitty A. Roy
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR, United States
| | - Laurel Pfeifer-Meister
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR, United States
- Environmental Science Institute, University of Oregon, Eugene, OR, United States
| | - Bart R. Johnson
- Department of Landscape Architecture, University of Oregon, Eugene, OR, United States
| | - Scott D. Bridgham
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR, United States
- Environmental Science Institute, University of Oregon, Eugene, OR, United States
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Yospin GI, Bridgham SD, Neilson RP, Bolte JP, Bachelet DM, Gould PJ, Harrington CA, Kertis JA, Evers C, Johnson BR. A new model to simulate climate-change impacts on forest succession for local land management. Ecol Appl 2015; 25:226-242. [PMID: 26255370 DOI: 10.1890/13-0906.1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We developed a new climate-sensitive vegetation state-and-transition simulation model (CV-STSM) to simulate future vegetation at a fine spatial grain commensurate with the scales of human land-use decisions, and under the joint influences of changing climate, site productivity, and disturbance. CV-STSM integrates outputs from four different modeling systems. Successional changes in tree species composition and stand structure were represented as transition probabilities and organized into a state-and-transition simulation model. States were characterized based on assessments of both current vegetation and of projected future vegetation from a dynamic global vegetation model (DGVM). State definitions included sufficient detail to support the integration of CV-STSM with an agent-based model of land-use decisions and a mechanistic model of fire behavior and spread. Transition probabilities were parameterized using output from a stand biometric model run across a wide range of site productivities. Biogeographic and biogeochemical projections from the DGVM were used to adjust the transition probabilities to account for the impacts of climate change on site productivity and potential vegetation type. We conducted experimental simulations in the Willamette Valley, Oregon, USA. Our simulation landscape incorporated detailed new assessments of critically imperiled Oregon white oak (Quercus garryana) savanna and prairie habitats among the suite of existing and future vegetation types. The experimental design fully crossed four future climate scenarios with three disturbance scenarios. CV-STSM showed strong interactions between climate and disturbance scenarios. All disturbance scenarios increased the abundance of oak savanna habitat, but an interaction between the most intense disturbance and climate-change scenarios also increased the abundance of subtropical tree species. Even so, subtropical tree species were far less abundant at the end of simulations in CV-STSM than in the dynamic global vegetation model simulations. Our results indicate that dynamic global vegetation models may overestimate future rates of vegetation change, especially in the absence of stand-replacing disturbances. Modeling tools such as CV-STSM that simulate rates and direction of vegetation change affected by interactions and feedbacks between climate and land-use change can help policy makers, land managers, and society as a whole develop effective plans to adapt to rapidly changing climate.
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20
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Reynolds LL, Johnson BR, Pfeifer-Meister L, Bridgham SD. Soil respiration response to climate change in Pacific Northwest prairies is mediated by a regional Mediterranean climate gradient. Glob Chang Biol 2015; 21:487-500. [PMID: 25205511 DOI: 10.1111/gcb.12732] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Revised: 08/04/2014] [Accepted: 08/25/2014] [Indexed: 06/03/2023]
Abstract
Soil respiration is expected to increase with rising global temperatures but the degree of response may depend on soil moisture and other local factors. Experimental climate change studies from single sites cannot discern whether an observed response is site-dependent or generalizable. To deconvolve site-specific vs. regional climatic controls, we examined soil respiration for 18 months along a 520 km climate gradient in three Pacific Northwest, USA prairies that represents increasingly severe Mediterranean conditions from north to south. At each site we implemented a fully factorial combination of 2.5-3 °C warming and 20% added precipitation intensity. The response of soil respiration to warming was driven primarily by the latitudinal climate gradient and not site-specific factors. Warming increased respiration at all sites during months when soil moisture was not limiting. However, these gains were offset by reductions in respiration during seasonal transitions and summer drought due to lengthened periods of soil moisture limitation. The degree of this offset varied along the north-south climate gradient such that in 2011 warming increased cumulative annual soil respiration 28.6% in the northern site, 13.5% in the central site, and not at all in the southern site. Precipitation also stimulated soil respiration more frequently in the south, consistent with an increased duration of moisture limitation. The best predictors of soil respiration in nonlinear models were the Normalized Difference Vegetation Index (NDVI), antecedent soil moisture, and temperature but these models provided biased results at high and low soil respiration. NDVI was an effective integrator of climate and site differences in plant productivity in terms of their combined effects on soil respiration. Our results suggest that soil moisture limitation can offset the effect of warming on soil respiration, and that greater growing-season moisture limitation would constrain cumulative annual responses to warming.
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Affiliation(s)
- Lorien L Reynolds
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR, 97403, USA
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McCarrick H, Flanigan D, Jones G, Johnson BR, Ade P, Araujo D, Bradford K, Cantor R, Che G, Day P, Doyle S, Leduc H, Limon M, Luu V, Mauskopf P, Miller A, Mroczkowski T, Tucker C, Zmuidzinas J. Horn-coupled, commercially-fabricated aluminum lumped-element kinetic inductance detectors for millimeter wavelengths. Rev Sci Instrum 2014; 85:123117. [PMID: 25554282 DOI: 10.1063/1.4903855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We discuss the design, fabrication, and testing of prototype horn-coupled, lumped-element kinetic inductance detectors (LEKIDs) designed for cosmic microwave background studies. The LEKIDs are made from a thin aluminum film deposited on a silicon wafer and patterned using standard photolithographic techniques at STAR Cryoelectronics, a commercial device foundry. We fabricated 20-element arrays, optimized for a spectral band centered on 150 GHz, to test the sensitivity and yield of the devices as well as the multiplexing scheme. We characterized the detectors in two configurations. First, the detectors were tested in a dark environment with the horn apertures covered, and second, the horn apertures were pointed towards a beam-filling cryogenic blackbody load. These tests show that the multiplexing scheme is robust and scalable, the yield across multiple LEKID arrays is 91%, and the measured noise-equivalent temperatures for a 4 K optical load are in the range 26±6 μK√s.
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Affiliation(s)
- H McCarrick
- Department of Physics, Columbia University, New York, New York 10025, USA
| | - D Flanigan
- Department of Physics, Columbia University, New York, New York 10025, USA
| | - G Jones
- Department of Physics, Columbia University, New York, New York 10025, USA
| | - B R Johnson
- Department of Physics, Columbia University, New York, New York 10025, USA
| | - P Ade
- School of Physics and Astronomy, Cardiff University, Cardiff, Wales CF24 3AA, United Kingdom
| | - D Araujo
- Department of Physics, Columbia University, New York, New York 10025, USA
| | - K Bradford
- Department of Physics, Arizona State University, Tempe, Arizona 85287, USA
| | - R Cantor
- STAR Cryoelectronics, Santa Fe, New Mexico 87508, USA
| | - G Che
- Department of Physics, Arizona State University, Tempe, Arizona 85287, USA
| | - P Day
- Jet Propulsion Laboratory, Caltech, Pasadena, California 91109, USA
| | - S Doyle
- School of Physics and Astronomy, Cardiff University, Cardiff, Wales CF24 3AA, United Kingdom
| | - H Leduc
- Jet Propulsion Laboratory, Caltech, Pasadena, California 91109, USA
| | - M Limon
- Department of Physics, Columbia University, New York, New York 10025, USA
| | - V Luu
- Department of Physics, Columbia University, New York, New York 10025, USA
| | - P Mauskopf
- School of Physics and Astronomy, Cardiff University, Cardiff, Wales CF24 3AA, United Kingdom
| | - A Miller
- Department of Physics, Columbia University, New York, New York 10025, USA
| | | | - C Tucker
- School of Physics and Astronomy, Cardiff University, Cardiff, Wales CF24 3AA, United Kingdom
| | - J Zmuidzinas
- Jet Propulsion Laboratory, Caltech, Pasadena, California 91109, USA
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Pfeifer-Meister L, Bridgham SD, Little CJ, Reynolds LL, Goklany ME, Johnson BR. Pushing the limit: experimental evidence of climate effects on plant range distributions. Ecology 2013; 94:2131-7. [DOI: 10.1890/13-0284.1] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Rosa-Bray M, Wisdom C, Wada S, Johnson BR, Grifols-Roura V, Grifols-Lucas V. Prospective multicentre study of the effect of voluntary plasmapheresis on plasma cholesterol levels in donors. Vox Sang 2013; 105:108-15. [PMID: 23517282 PMCID: PMC3813983 DOI: 10.1111/vox.12031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Revised: 01/17/2013] [Accepted: 01/19/2013] [Indexed: 11/29/2022]
Abstract
Background and Objectives LDL apheresis is used to treat patients with familial hypercholesterolaemia, and low-volume plasmapheresis for plasma donation may similarly lower cholesterol levels in some donors. This study was designed to assess the effect of plasmapheresis on total, LDL and HDL cholesterol levels in a plasma donor population. Materials and Methods This was a prospective, unblinded longitudinal cohort study in which a blood sample was obtained for analysis before each donation. Data from 663 donors were analysed using a multivariable repeated measures regression model with a general estimating equations approach with changes in cholesterol as the primary outcome measure. Results The model predicted a significant decrease in total and LDL cholesterol for both genders and all baseline cholesterol levels (P < 0·01). The greatest total cholesterol decreases (women, −46·8 mg/dL; men, −32·2 mg/dL) were associated with high baseline levels and 2–4 days between donations. Small but statistically significant increases (P ≤ 0·01) in HDL cholesterol were predicted for donors with low baseline levels. Conclusions These results suggest that, in donors with elevated baseline cholesterol levels, total and LDL cholesterol levels may decrease during routine voluntary plasmapheresis.
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Affiliation(s)
- M Rosa-Bray
- Grifols, Plasma Operations, Los Angeles, CA, USA.
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de Almeida-Neto C, Goncalez TT, Birch RJ, de Carvalho SMF, Capuani L, Leão SC, Miranda C, Rocha PC, Carneiro-Proietti AB, Johnson BR, Wright DJ, Murphy EL, Custer B. Risk factors for human immunodeficiency virus infection among Brazilian blood donors: a multicentre case-control study using audio computer-assisted structured interviews. Vox Sang 2013; 105:91-9. [PMID: 23517235 DOI: 10.1111/vox.12028] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Revised: 01/09/2013] [Accepted: 01/13/2013] [Indexed: 11/30/2022]
Abstract
BACKGROUND Although risk factors for HIV infection are known, it is important for blood centres to understand local epidemiology and disease transmission patterns. Current risk factors for HIV infection in blood donors in Brazil were assessed. METHODS A case-control study was conducted at large public blood centres located in four major cities between April 2009 and March 2011. Cases were persons whose donations were confirmed positive by enzyme immunoassays followed by Western blot confirmation. Audio computer-assisted structured interviews (ACASI) were completed by all cases and controls. Multivariable logistic regression was used to estimate adjusted odds ratios (AORs) and associated 95% confidence intervals (CIs). RESULTS There were 341 cases, including 47 with recently acquired infection, and 791 controls. Disclosed risk factors for both females and males were sex with an HIV-positive person AOR 11.3, 95% CI (4.1, 31.7) and being an IVDU or sexual partner of an IVDU [AOR 4.65 (1.8, 11.7)]. For female blood donors, additional risk factors were having male sex partners who also are MSM [AOR 13.5 (3.1, 59.8)] and having unprotected sex with multiple sexual partners [AOR 5.19 (2.1, 12.9)]. The primary risk factor for male blood donors was MSM activity [AOR 21.6 (8.8, 52.9)]. Behaviours associated with recently acquired HIV were being a MSM or sex partner of MSM [13.82, (4.7, 40.3)] and IVDU [11.47, (3.0, 43.2)]. CONCLUSION Risk factors in blood donors parallel those in the general population in Brazil. Identified risk factors suggest that donor compliance with selection procedures at the participating blood centres is inadequate.
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Gambetta JM, Córcoles AD, Merkel ST, Johnson BR, Smolin JA, Chow JM, Ryan CA, Rigetti C, Poletto S, Ohki TA, Ketchen MB, Steffen M. Characterization of addressability by simultaneous randomized benchmarking. Phys Rev Lett 2012; 109:240504. [PMID: 23368295 DOI: 10.1103/physrevlett.109.240504] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Revised: 10/24/2012] [Indexed: 06/01/2023]
Abstract
The control and handling of errors arising from cross talk and unwanted interactions in multiqubit systems is an important issue in quantum information processing architectures. We introduce a benchmarking protocol that provides information about the amount of addressability present in the system and implement it on coupled superconducting qubits. The protocol consists of randomized benchmarking experiments run both individually and simultaneously on pairs of qubits. A relevant figure of merit for the addressability is then related to the differences in the measured average gate fidelities in the two experiments. We present results from two similar samples with differing cross talk and unwanted qubit-qubit interactions. The results agree with predictions based on simple models of the classical cross talk and Stark shifts.
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Affiliation(s)
- Jay M Gambetta
- IBM TJ Watson Research Center, Yorktown Heights, New York 10598, USA
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Pfeifer-Meister L, Johnson BR, Roy BA, Carreño S, Stewart JL, Bridgham SD. Restoring wetland prairies: tradeoffs among native plant cover, community composition, and ecosystem functioning. Ecosphere 2012. [DOI: 10.1890/es12-00261.1] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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28
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Magesan E, Gambetta JM, Johnson BR, Ryan CA, Chow JM, Merkel ST, da Silva MP, Keefe GA, Rothwell MB, Ohki TA, Ketchen MB, Steffen M. Efficient measurement of quantum gate error by interleaved randomized benchmarking. Phys Rev Lett 2012; 109:080505. [PMID: 23002731 DOI: 10.1103/physrevlett.109.080505] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2012] [Indexed: 06/01/2023]
Abstract
We describe a scalable experimental protocol for estimating the average error of individual quantum computational gates. This protocol consists of interleaving random Clifford gates between the gate of interest and provides an estimate as well as theoretical bounds for the average error of the gate under test, so long as the average noise variation over all Clifford gates is small. This technique takes into account both state preparation and measurement errors and is scalable in the number of qubits. We apply this protocol to a superconducting qubit system and find a bounded average error of 0.003 [0,0.016] for the single-qubit gates X(π/2) and Y(π/2). These bounded values provide better estimates of the average error than those extracted via quantum process tomography.
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Affiliation(s)
- Easwar Magesan
- Department of Applied Mathematics, University of Waterloo, Waterloo, Ontario, Canada
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29
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Dobbs MA, Lueker M, Aird KA, Bender AN, Benson BA, Bleem LE, Carlstrom JE, Chang CL, Cho HM, Clarke J, Crawford TM, Crites AT, Flanigan DI, de Haan T, George EM, Halverson NW, Holzapfel WL, Hrubes JD, Johnson BR, Joseph J, Keisler R, Kennedy J, Kermish Z, Lanting TM, Lee AT, Leitch EM, Luong-Van D, McMahon JJ, Mehl J, Meyer SS, Montroy TE, Padin S, Plagge T, Pryke C, Richards PL, Ruhl JE, Schaffer KK, Schwan D, Shirokoff E, Spieler HG, Staniszewski Z, Stark AA, Vanderlinde K, Vieira JD, Vu C, Westbrook B, Williamson R. Frequency multiplexed superconducting quantum interference device readout of large bolometer arrays for cosmic microwave background measurements. Rev Sci Instrum 2012; 83:073113. [PMID: 22852677 DOI: 10.1063/1.4737629] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
A technological milestone for experiments employing transition edge sensor bolometers operating at sub-Kelvin temperature is the deployment of detector arrays with 100s-1000s of bolometers. One key technology for such arrays is readout multiplexing: the ability to read out many sensors simultaneously on the same set of wires. This paper describes a frequency-domain multiplexed readout system which has been developed for and deployed on the APEX-SZ and South Pole Telescope millimeter wavelength receivers. In this system, the detector array is divided into modules of seven detectors, and each bolometer within the module is biased with a unique ∼MHz sinusoidal carrier such that the individual bolometer signals are well separated in frequency space. The currents from all bolometers in a module are summed together and pre-amplified with superconducting quantum interference devices operating at 4 K. Room temperature electronics demodulate the carriers to recover the bolometer signals, which are digitized separately and stored to disk. This readout system contributes little noise relative to the detectors themselves, is remarkably insensitive to unwanted microphonic excitations, and provides a technology pathway to multiplexing larger numbers of sensors.
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Affiliation(s)
- M A Dobbs
- Physics Department, McGill University, Montreal, Quebec H3A 2T8, Canada
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30
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Sun L, DiCarlo L, Reed MD, Catelani G, Bishop LS, Schuster DI, Johnson BR, Yang GA, Frunzio L, Glazman L, Devoret MH, Schoelkopf RJ. Measurements of quasiparticle tunneling dynamics in a band-gap-engineered transmon qubit. Phys Rev Lett 2012; 108:230509. [PMID: 23003936 DOI: 10.1103/physrevlett.108.230509] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2011] [Indexed: 06/01/2023]
Abstract
We have engineered the band gap profile of transmon qubits by combining oxygen-doped Al for tunnel junction electrodes and clean Al as quasiparticle traps to investigate energy relaxation due to quasiparticle tunneling. The relaxation time T1 of the qubits is shown to be insensitive to this band gap engineering. Operating at relatively low-E(J)/E(C) makes the transmon transition frequency distinctly dependent on the charge parity, allowing us to detect the quasiparticles tunneling across the qubit junction. Quasiparticle kinetics have been studied by monitoring the frequency switching due to even-odd parity change in real time. It shows the switching time is faster than 10 μs, indicating quasiparticle-induced relaxation has to be reduced to achieve T1 much longer than 100 μs.
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Affiliation(s)
- L Sun
- Department of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA
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31
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Paik H, Schuster DI, Bishop LS, Kirchmair G, Catelani G, Sears AP, Johnson BR, Reagor MJ, Frunzio L, Glazman LI, Girvin SM, Devoret MH, Schoelkopf RJ. Observation of high coherence in Josephson junction qubits measured in a three-dimensional circuit QED architecture. Phys Rev Lett 2011; 107:240501. [PMID: 22242979 DOI: 10.1103/physrevlett.107.240501] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2011] [Revised: 09/15/2011] [Indexed: 05/27/2023]
Abstract
Superconducting quantum circuits based on Josephson junctions have made rapid progress in demonstrating quantum behavior and scalability. However, the future prospects ultimately depend upon the intrinsic coherence of Josephson junctions, and whether superconducting qubits can be adequately isolated from their environment. We introduce a new architecture for superconducting quantum circuits employing a three-dimensional resonator that suppresses qubit decoherence while maintaining sufficient coupling to the control signal. With the new architecture, we demonstrate that Josephson junction qubits are highly coherent, with T2 ∼ 10 to 20 μs without the use of spin echo, and highly stable, showing no evidence for 1/f critical current noise. These results suggest that the overall quality of Josephson junctions in these qubits will allow error rates of a few 10(-4), approaching the error correction threshold.
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Affiliation(s)
- Hanhee Paik
- Department of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA
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32
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Schwan D, Ade PAR, Basu K, Bender AN, Bertoldi F, Cho HM, Chon G, Clarke J, Dobbs M, Ferrusca D, Güsten R, Halverson NW, Holzapfel WL, Horellou C, Johansson D, Johnson BR, Kennedy J, Kermish Z, Kneissl R, Lanting T, Lee AT, Lueker M, Mehl J, Menten KM, Muders D, Pacaud F, Plagge T, Reichardt CL, Richards PL, Schaaf R, Schilke P, Sommer MW, Spieler H, Tucker C, Weiss A, Westbrook B, Zahn O. Invited article: millimeter-wave bolometer array receiver for the Atacama pathfinder experiment Sunyaev-Zel'dovich (APEX-SZ) instrument. Rev Sci Instrum 2011; 82:091301. [PMID: 21974566 DOI: 10.1063/1.3637460] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The Atacama pathfinder experiment Sunyaev-Zel'dovich (APEX-SZ) instrument is a millimeter-wave cryogenic receiver designed to observe galaxy clusters via the Sunyaev-Zel'dovich effect from the 12 m APEX telescope on the Atacama plateau in Chile. The receiver contains a focal plane of 280 superconducting transition-edge sensor (TES) bolometers instrumented with a frequency-domain multiplexed readout system. The bolometers are cooled to 280 mK via a three-stage helium sorption refrigerator and a mechanical pulse-tube cooler. Three warm mirrors, two 4 K lenses, and a horn array couple the TES bolometers to the telescope. APEX-SZ observes in a single frequency band at 150 GHz with 1' angular resolution and a 22' field-of-view, all well suited for cluster mapping. The APEX-SZ receiver has played a key role in the introduction of several new technologies including TES bolometers, the frequency-domain multiplexed readout, and the use of a pulse-tube cooler with bolometers. As a result of these new technologies, the instrument has a higher instantaneous sensitivity and covers a larger field-of-view than earlier generations of Sunyaev-Zel'dovich instruments. The TES bolometers have a median sensitivity of 890 μK(CMB)√s (NEy of 3.5 × 10(-4) √s). We have also demonstrated upgraded detectors with improved sensitivity of 530 μK(CMB)√s (NEy of 2.2 × 10(-4) √s). Since its commissioning in April 2007, APEX-SZ has been used to map 48 clusters. We describe the design of the receiver and its performance when installed on the APEX telescope.
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Affiliation(s)
- D Schwan
- Department of Physics, University of California, Berkeley, California 94720, USA.
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33
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Chow JM, Córcoles AD, Gambetta JM, Rigetti C, Johnson BR, Smolin JA, Rozen JR, Keefe GA, Rothwell MB, Ketchen MB, Steffen M. Simple all-microwave entangling gate for fixed-frequency superconducting qubits. Phys Rev Lett 2011; 107:080502. [PMID: 21929152 DOI: 10.1103/physrevlett.107.080502] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Indexed: 05/31/2023]
Abstract
We demonstrate an all-microwave two-qubit gate on superconducting qubits which are fixed in frequency at optimal bias points. The gate requires no additional subcircuitry and is tunable via the amplitude of microwave irradiation on one qubit at the transition frequency of the other. We use the gate to generate entangled states with a maximal extracted concurrence of 0.88, and quantum process tomography reveals a gate fidelity of 81%.
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Affiliation(s)
- Jerry M Chow
- IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, USA
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34
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Bachelet D, Johnson BR, Bridgham SD, Dunn PV, Anderson HE, Rogers BM. Climate Change Impacts on Western Pacific Northwest Prairies and Savannas. Northwest Science 2011. [DOI: 10.3955/046.085.0224] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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35
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Dicarlo L, Reed MD, Sun L, Johnson BR, Chow JM, Gambetta JM, Frunzio L, Girvin SM, Devoret MH, Schoelkopf RJ. Preparation and measurement of three-qubit entanglement in a superconducting circuit. Nature 2010; 467:574-8. [PMID: 20882013 DOI: 10.1038/nature09416] [Citation(s) in RCA: 443] [Impact Index Per Article: 31.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2010] [Accepted: 08/09/2010] [Indexed: 11/09/2022]
Abstract
Traditionally, quantum entanglement has been central to foundational discussions of quantum mechanics. The measurement of correlations between entangled particles can have results at odds with classical behaviour. These discrepancies grow exponentially with the number of entangled particles. With the ample experimental confirmation of quantum mechanical predictions, entanglement has evolved from a philosophical conundrum into a key resource for technologies such as quantum communication and computation. Although entanglement in superconducting circuits has been limited so far to two qubits, the extension of entanglement to three, eight and ten qubits has been achieved among spins, ions and photons, respectively. A key question for solid-state quantum information processing is whether an engineered system could display the multi-qubit entanglement necessary for quantum error correction, which starts with tripartite entanglement. Here, using a circuit quantum electrodynamics architecture, we demonstrate deterministic production of three-qubit Greenberger-Horne-Zeilinger (GHZ) states with fidelity of 88 per cent, measured with quantum state tomography. Several entanglement witnesses detect genuine three-qubit entanglement by violating biseparable bounds by 830 ± 80 per cent. We demonstrate the first step of basic quantum error correction, namely the encoding of a logical qubit into a manifold of GHZ-like states using a repetition code. The integration of this encoding with decoding and error-correcting steps in a feedback loop will be the next step for quantum computing with integrated circuits.
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Affiliation(s)
- L Dicarlo
- Department of Physics, Yale University, New Haven, Connecticut 06511, USA.
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36
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Reed MD, DiCarlo L, Johnson BR, Sun L, Schuster DI, Frunzio L, Schoelkopf RJ. High-fidelity readout in circuit quantum electrodynamics using the Jaynes-Cummings nonlinearity. Phys Rev Lett 2010; 105:173601. [PMID: 21231043 DOI: 10.1103/physrevlett.105.173601] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2010] [Indexed: 05/30/2023]
Abstract
We demonstrate a qubit readout scheme that exploits the Jaynes-Cummings nonlinearity of a superconducting cavity coupled to transmon qubits. We find that, in the strongly driven dispersive regime of this system, there is the unexpected onset of a high-transmission "bright" state at a critical power which depends sensitively on the initial qubit state. A simple and robust measurement protocol exploiting this effect achieves a single-shot fidelity of 87% using a conventional sample design and experimental setup, and at least 61% fidelity to joint correlations of three qubits.
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Affiliation(s)
- M D Reed
- Departments of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA
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37
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Chow JM, Gambetta JM, Tornberg L, Koch J, Bishop LS, Houck AA, Johnson BR, Frunzio L, Girvin SM, Schoelkopf RJ. Randomized benchmarking and process tomography for gate errors in a solid-state qubit. Phys Rev Lett 2009; 102:090502. [PMID: 19392502 DOI: 10.1103/physrevlett.102.090502] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2008] [Indexed: 05/27/2023]
Abstract
We present measurements of single-qubit gate errors for a superconducting qubit. Results from quantum process tomography and randomized benchmarking are compared with gate errors obtained from a double pi pulse experiment. Randomized benchmarking reveals a minimum average gate error of 1.1+/-0.3% and a simple exponential dependence of fidelity on the number of gates. It shows that the limits on gate fidelity are primarily imposed by qubit decoherence, in agreement with theory.
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Affiliation(s)
- J M Chow
- Department of Physics, Yale University, New Haven, Connecticut 06520, USA
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38
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Copp JB, Johnson BR, Shaw A, Burbano MS, Narayanan B, Frank K, Kinnear D, Melcer H, Brischke K. A balancing act: the consulting engineers' pragmatic view of process modelling. Water Sci Technol 2009; 59:763-769. [PMID: 19237771 DOI: 10.2166/wst.2009.594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Modelling: what do we know, what do we want to know and why? The practical application of models to real projects is often circular because these questions weren't asked prior to making the decision to model the plant under study. Modelling wastewater treatment plants can provide insight into the inner workings of the process that might not be attainable any other way, but is that added process knowledge always needed or necessary and what criteria does one use to determine the level of effort required? These complex modelling decisions require education, communication, and improved understanding amongst both modellers and clients. This submission explores the use of models by consultants for consulting purposes and the balancing acts (time versus knowledge and cost versus benefit) that the consulting engineer must manage when embarking on any modelling project.
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Affiliation(s)
- J B Copp
- Primodal, Inc., 122 Leland Street, Hamilton, L8S 3A4, Ontario, Canada.
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39
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Houck AA, Schreier JA, Johnson BR, Chow JM, Koch J, Gambetta JM, Schuster DI, Frunzio L, Devoret MH, Girvin SM, Schoelkopf RJ. Controlling the spontaneous emission of a superconducting transmon qubit. Phys Rev Lett 2008; 101:080502. [PMID: 18764596 DOI: 10.1103/physrevlett.101.080502] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2008] [Indexed: 05/26/2023]
Abstract
We present a detailed characterization of coherence in seven transmon qubits in a circuit QED architecture. We find that spontaneous emission rates are strongly influenced by far off-resonant modes of the cavity and can be understood within a semiclassical circuit model. A careful analysis of the spontaneous qubit decay into a microwave transmission-line cavity can accurately predict the qubit lifetimes over 2 orders of magnitude in time and more than an octave in frequency. Coherence times T1 and T_{2};{*} of more than a microsecond are reproducibly demonstrated.
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Affiliation(s)
- A A Houck
- Departments of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA
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40
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Majer J, Chow JM, Gambetta JM, Koch J, Johnson BR, Schreier JA, Frunzio L, Schuster DI, Houck AA, Wallraff A, Blais A, Devoret MH, Girvin SM, Schoelkopf RJ. Coupling superconducting qubits via a cavity bus. Nature 2007; 449:443-7. [PMID: 17898763 DOI: 10.1038/nature06184] [Citation(s) in RCA: 221] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2007] [Accepted: 08/16/2007] [Indexed: 11/09/2022]
Abstract
Superconducting circuits are promising candidates for constructing quantum bits (qubits) in a quantum computer; single-qubit operations are now routine, and several examples of two-qubit interactions and gates have been demonstrated. These experiments show that two nearby qubits can be readily coupled with local interactions. Performing gate operations between an arbitrary pair of distant qubits is highly desirable for any quantum computer architecture, but has not yet been demonstrated. An efficient way to achieve this goal is to couple the qubits to a 'quantum bus', which distributes quantum information among the qubits. Here we show the implementation of such a quantum bus, using microwave photons confined in a transmission line cavity, to couple two superconducting qubits on opposite sides of a chip. The interaction is mediated by the exchange of virtual rather than real photons, avoiding cavity-induced loss. Using fast control of the qubits to switch the coupling effectively on and off, we demonstrate coherent transfer of quantum states between the qubits. The cavity is also used to perform multiplexed control and measurement of the qubit states. This approach can be expanded to more than two qubits, and is an attractive architecture for quantum information processing on a chip.
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Affiliation(s)
- J Majer
- Department of Applied Physics, Yale University, New Haven, Connecticut 06520, USA.
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41
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Houck AA, Schuster DI, Gambetta JM, Schreier JA, Johnson BR, Chow JM, Frunzio L, Majer J, Devoret MH, Girvin SM, Schoelkopf RJ. Generating single microwave photons in a circuit. Nature 2007; 449:328-31. [PMID: 17882217 DOI: 10.1038/nature06126] [Citation(s) in RCA: 339] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2007] [Accepted: 07/24/2007] [Indexed: 11/08/2022]
Abstract
Microwaves have widespread use in classical communication technologies, from long-distance broadcasts to short-distance signals within a computer chip. Like all forms of light, microwaves, even those guided by the wires of an integrated circuit, consist of discrete photons. To enable quantum communication between distant parts of a quantum computer, the signals must also be quantum, consisting of single photons, for example. However, conventional sources can generate only classical light, not single photons. One way to realize a single-photon source is to collect the fluorescence of a single atom. Early experiments measured the quantum nature of continuous radiation, and further advances allowed triggered sources of photons on demand. To allow efficient photon collection, emitters are typically placed inside optical or microwave cavities, but these sources are difficult to employ for quantum communication on wires within an integrated circuit. Here we demonstrate an on-chip, on-demand single-photon source, where the microwave photons are injected into a wire with high efficiency and spectral purity. This is accomplished in a circuit quantum electrodynamics architecture, with a microwave transmission line cavity that enhances the spontaneous emission of a single superconducting qubit. When the qubit spontaneously emits, the generated photon acts as a flying qubit, transmitting the quantum information across a chip. We perform tomography of both the qubit and the emitted photons, clearly showing that both the quantum phase and amplitude are transferred during the emission. Both the average power and voltage of the photon source are characterized to verify performance of the system. This single-photon source is an important addition to a rapidly growing toolbox for quantum optics on a chip.
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Affiliation(s)
- A A Houck
- Department of Applied Physics, Yale University, New Haven, Connecticut 06520, USA
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42
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Affiliation(s)
- B R Johnson
- Laboratories of the Engineering Experiment Station and the Department of Bacteriology of the Iowa State College, Ames, Iowa
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Abstract
The ADM 1 model has been implemented in a steady-state whole wastewater plant simulator. The ADM 1 model has been in use with good success for approximately 2 years on a wide range of wastewater treatment facilities. However, a number of modifications were necessary to allow it to be used in the context of municipal wastewater treatment. It was found that the model's use was greatly simplified if used in conjunction with a larger plant simulator to assist in the feed fractionation. It was also found that a better fit to actual operating data was achieved if some of the slowly biodegradable particulate fraction was partitioned into ADM particulate fractions other than the composite fraction. Another significant limitation of the model is in the absence of phosphorus modeling. The ADM model needs to have phosphorus handling for all the relevant fractions, and needs to include the handling of inorganic reactions such as struvite precipitation and metal phosphate/metal hydroxide precipitation. Activity effects on chemical equilibria are significant when considering phosphorus. Also of importance in wastewater treatment is the fate of sulfur compounds. This includes the generation of H2S in the digester gas and the fate of the sulfur species in the digested sludge (as a predictor of odour-generating potential).
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Shang Y, Johnson BR, Sieger R. Application of the IWA anaerobic digestion model (ADM1) for simulating full-scale anaerobic sewage sludge digestion. Water Sci Technol 2005; 52:487-92. [PMID: 16180468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
A steady-state implementation of the IWA Anaerobic Digestion Model No. 1 (ADM1) has been applied to the anaerobic digesters in two wastewater treatment plants. The two plants have a wastewater treatment capacity of 76,000 and 820,000 m3/day, respectively, with approximately 12 and 205 dry metric tons sludge fed to digesters per day. The main purpose of this study is to compare the ADM1 model results with full-scale anaerobic digestion performance. For both plants, the prediction of the steady-state ADM1 implementation using the suggested physico-chemical and biochemical parameter values was able to reflect the results from the actual digester operations to a reasonable degree of accuracy on all parameters. The predicted total solids (TS) and volatile solids (VS) concentration in the digested biosolids, as well as the digester volatile solids destruction (VSD), biogas production and biogas yield are within 10% of the actual digester data. This study demonstrated that the ADM1 is a powerful tool for predicting the steady-state behaviour of anaerobic digesters treating sewage sludges. In addition, it showed that the use of a whole wastewater treatment plant simulator for fractionating the digester influent into the ADM1 input parameters was successful.
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Affiliation(s)
- Y Shang
- CH2M HILL, 3 Hutton Centre Drive, Suite 200, Santa Ana, CA 92707, USA.
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Johnson BR, Goodwin S, Daigger GT, Crawford GV. A comparison between the theory and reality of full-scale step-feed nutrient removal systems. Water Sci Technol 2005; 52:587-96. [PMID: 16459837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Capacity enhancement and volume reduction benefits of step-feeding fully aerobic bioreactors has been well documented. Application of step-feed technology to biological nutrient removal (BNR) systems, particularly those removing nitrogen alone or both nitrogen and phosphorus, is relatively new to the industry. In recent years, a number of full-scale step-feed facilities have been brought into service. This paper reviews nine full-scale step-feed biological nutrient removal systems--both nitrogen removal alone, and nitrogen and phosphorus removal. The objective is to compare the theoretical benefits of such systems with their actual operation. The predicted benefits of reduced bioreactor volume or increased process capacity, reduced energy usage, more robust nitrification performance, and the flexibility to tune (or de-tune) nitrification efficiency were verified in full-scale systems. Equations are also presented that may be used in the prediction of step-feed benefits. There are two primary drivers for considering a step-feed biological reactor system: 1. Reduced bioreactor volume for a defined capacity or performance or increased process capacity given a fixed bioreactor volume. 2. More robust nitrification performance. Full-scale operation of these step-feed nutrient removal systems provides a real world basis for the claimed benefits of step-feed operation. These systems have uniformly shown additional capacity. A number of them have also exhibited more robust performance, especially during storms. Where possible, side-by-side comparisons of full-scale step-feed systems with non-step-feed systems have exhibited greater process reliability and flexibility.
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Affiliation(s)
- B R Johnson
- CH2M HILL, 700 Clearwater Lane, Boise, Idaho 83712, USA
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46
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Johnson BR, Weeks SM. Implants and endodontics. II. J Am Dent Assoc 2001; 132:722, 724. [PMID: 11433849 DOI: 10.14219/jada.archive.2001.0255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Land BR, Wyttenbach RA, Johnson BR. Tools for physiology labs: an inexpensive high-performance amplifier and electrode for extracellular recording. J Neurosci Methods 2001; 106:47-55. [PMID: 11248340 DOI: 10.1016/s0165-0270(01)00328-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The cost of electronic equipment can be a critical barrier to including neurophysiology exercises in biology teaching programs. We describe the construction of a simple and inexpensive AC preamplifier with performance comparable to that of commercial products. The amplifier consists of two integrated circuits in five stages: differential input, fixed gain, variable gain (100 or 1000), low-pass filter (5 or 20 kHz), and 50 or 60 Hz notch filter. We compared our amplifier with two commercial units, the A-M Systems Model 1700 and the Grass P15. The quality of extracellular recording from a typical student preparation (spontaneously active crayfish motor nerve) was the same for all three amplifiers, although our amplifier has slightly higher internal noise than the P15 and slightly lower common-mode rejection than the 1700 and P15. In addition, we describe a simple suction electrode for extracellular nerve recording. It is easily constructed from readily available materials and uses a disposable plastic pipette tip, instead of the traditional glass tip, to contact the nerve. This tip is easily replaced if broken or clogged, and can be adapted to different recording conditions by selecting a different tip size or stretching the plastic. Development of this equipment is part of an ongoing project to promote neuroscience education by expanding the neurophysiology options available to laboratory instructors.
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Affiliation(s)
- B R Land
- Department of Neurobiology and Behavior, Cornell University, Mudd Hall, Ithaca, NY 14853, USA
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Carrithers SL, Taylor B, Cai WY, Johnson BR, Ott CE, Greenberg RN, Jackson BA. Guanylyl cyclase-C receptor mRNA distribution along the rat nephron. Regul Pept 2000; 95:65-74. [PMID: 11062334 DOI: 10.1016/s0167-0115(00)00139-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Guanylin (GN) and uroguanylin (UGN) are two recently identified peptides that have been shown to affect water and electrolyte transport in both the intestine and the kidney. Mechanistically, the effects of both peptides are thought to be mediated by intracellular cGMP which results from ligand binding to a plasma membrane guanylyl cyclase-C (GC-C) receptor. To date, the specific intrarenal site(s) of GN and UGN action have not been established. To begin to address this issue, the present studies utilized semi-quantitative RT-PCR to assess the distribution of GC-C mRNA in specific microdissected segments of the rat nephron. GC-C mRNA expression was highest in the cortical collecting tubule, followed by the proximal convoluted tubule, medullary thick ascending limb and collecting tubule, and thin limbs of Henle's loop. Expression levels were significantly lower in all other segments tested, including the glomerulus. The renal tubular expression pattern for cGMP-dependent protein kinase II (cGK-II) mRNA, which is activated in response to GN/UGN-dependent cGMP accumulation, was similar to that for GC-C. Notably, both GN and UGN mRNAs were also expressed along the nephron. The highest levels of expression for both peptides were detected in the medullary collecting tubule. Lower, but comparable levels of GN and UGN expression also occurred in the cortical collecting tubule, cortical and medullary thick ascending limb, and thin limbs of Henles loop. In the proximal convoluted tubule, GN mRNA expression was also quite high, while UGN mRNA was almost undetectable. The presence of renal GC-C and cGK-II in the kidney are consistent with a proposed endocrine function for GN and UGN. In addition however, the present data suggest that intrarenally synthesized GN and UGN may also contribute to the regulation of renal tubular transport.
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Affiliation(s)
- S L Carrithers
- Division of Infectious Diseases, University of Kentucky and Lexington Veterans Affairs Medical Center, Research Service 151-CDD, 1101 VA Drive, VAMC-D309, 40506, Lexington, KY, USA.
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Johnson BR. Sexual violence: the perpetrator. New Dir Ment Health Serv 2000:73-8. [PMID: 10885267 DOI: 10.1002/yd.23320008609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
In addition to assessing and treating victims of sexual violence, mental health professionals are also called upon to provide similar services for sexually violent perpetrators. This chapter addresses these concerns along with the forensic issues surrounding those who commit sexual violence.
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Affiliation(s)
- B R Johnson
- University of Arizona College of Medicine, Department of Psychiatry, USA
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Abstract
In addition to taking steps to ensure their own safety, clinicians also have a role in predicting violence. In the past the clinician's ability to accurately assess the risk for violence has been seriously questioned. This chapter provides guidance for making acceptable predictions.
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Affiliation(s)
- B R Johnson
- University of Arizona College of Medicine, Department of Psychiatry, USA
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