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1998

University of New Hampshire

Articles 1 - 30 of 39

Full-Text Articles in Physical Sciences and Mathematics

Wet Deposition In A Global Size-Dependent Aerosol Transport Model: 2. Influence Of The Scavenging Scheme On 210pb Vertical Profiles, Surface Concentrations, And Deposition, W Guelle, Y J. Balkanski, Jack E. Dibb, M Schulz, F Dulac Nov 1998

Wet Deposition In A Global Size-Dependent Aerosol Transport Model: 2. Influence Of The Scavenging Scheme On 210pb Vertical Profiles, Surface Concentrations, And Deposition, W Guelle, Y J. Balkanski, Jack E. Dibb, M Schulz, F Dulac

Earth Sciences

The main atmospheric sink for submicron aerosols is wet removal. Lead 210, the radioactive decay product of 222Rn, attaches immediately after being formed to submicron particles. Here we compare the effects of three different wet-scavenging schemes used in global aerosol simulations on the 210Pb aerosol distribution using an off-line, size-resolved, global atmospheric transport model. We highlight the merits and shortcomings of each scavenging scheme at reproducing available measurements, which include concentrations in surface air and deposition, as well as vertical profiles observed over North America and western and central North Pacific. We show that model-measurement comparison of total …

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Soluble Species In Aerosol And Snow And Their Relationship At Glacier 1, Tien Shan, China, Junying Sun, Dahe Qin, Paul A. Mayewski, Jack E. Dibb, Sallie I. Whitlow, Zhongqin Lee, Qinzhao Yang Nov 1998

Soluble Species In Aerosol And Snow And Their Relationship At Glacier 1, Tien Shan, China, Junying Sun, Dahe Qin, Paul A. Mayewski, Jack E. Dibb, Sallie I. Whitlow, Zhongqin Lee, Qinzhao Yang

Earth Sciences

Simultaneous sampling of aerosol (n = 20) and snow (n = 114) was made at Glacier 1, Tien Shan, between May 19 and June 29, 1996. Similar temporal patterns of some major ion (calcium, magnesium, potassium, sodium, chloride, and sulfate) concentrations between snow and aerosol show that snow chemistry basically reflects changes in the chemistry of the atmosphere. This gives us confidence in the reconstruction of past atmospheric change using some snow data. There are no significant correlations between aerosol and snow samples for ammonium and nitrate. This suggests that post-depositional and/or post-collection processes may alter ammonium and nitrate concentrations …

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Nitric Acid Scavenging By Mineral And Biomass Burning Aerosols, A Tabazadeh, M Z. Jacobson, H B. Singh, O Brian Toon, J S. Lin, R B. Chatfield, A N. Thakur, R. Talbot, Jack E. Dibb Nov 1998

Nitric Acid Scavenging By Mineral And Biomass Burning Aerosols, A Tabazadeh, M Z. Jacobson, H B. Singh, O Brian Toon, J S. Lin, R B. Chatfield, A N. Thakur, R. Talbot, Jack E. Dibb

Earth Sciences

The abundance of gas phase nitric acid in the upper troposphere is overestimated by global chemistry-transport models, especially during the spring and summer seasons. Recent aircraft data obtained over the central US show that mineral aerosols were abundant in the upper troposphere during spring. Chemical reactions on mineral dust may provide an important sink for nitric acid. In regions where the mineral dust abundance is low in the upper troposphere similar HNO3 removal processes may occur on biomass burning aerosols. We propose that mineral and biomass burning aerosols may provide an important global sink for gas phase nitric acid, …

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Development Of A Hard X-Ray Polarimeter For Astrophysics, Mark L. Mcconnell, John R. Macri, M Mcclish, James M. Ryan, D J. Forrest, W T. Vestrand Nov 1998

Development Of A Hard X-Ray Polarimeter For Astrophysics, Mark L. Mcconnell, John R. Macri, M Mcclish, James M. Ryan, D J. Forrest, W T. Vestrand

Space Science Center

We have been developing a Compton scatter polarimeter for measuring the linear polarization of hard X-rays (100-300 keV) from astrophysical sources. A laboratory prototype polarimeter has been used to successfully demonstrate the reliability of our Monte Carlo simulation code and to demonstrate our ability to generate a polarized photon source in the lab. Our design concept places a self-containedpolarimeter module on the front-end of a a 5-inch position sensitive PMT (PSPMT). We are currently working on the fabrication of a science model based on this PSPMT concept. Although the emphasis of our development effort is towards measuring hard X-rays from …

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Cusp Energetic Ions: A Bow Shock Source, S. W. Chang, J. D. Scudder, S. A. Fuselier, J. F. Fennell, K. J. Trattner, J. S. Pickett, Harlan E. Spence, J. D. Menietti, W. K. Peterson, R. P. Lepping, R. Friedel Oct 1998

Cusp Energetic Ions: A Bow Shock Source, S. W. Chang, J. D. Scudder, S. A. Fuselier, J. F. Fennell, K. J. Trattner, J. S. Pickett, Harlan E. Spence, J. D. Menietti, W. K. Peterson, R. P. Lepping, R. Friedel

Physics & Astronomy

Recent interpretations of cusp energetic ions observed by the POLAR spacecraft have suggested a new energization process in the cusp [Chen et al., 1997; 1998]. Simultaneous enhancement of H+, He+2, and O>+2 fluxes indicates that they are of solar wind origin. In the present study, we examine H+ and He+2 energy spectra from 20 eV to several 100 keV measured by the Hydra, Toroidal Imaging Mass-Angle Spectrograph (TIMAS), and Charge and Mass Magnetospheric Ion Composition Experiment (CAMMICE) on POLAR. The combined spectrum for each species is shown to be continuous with a …

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The Limits Of Spatial Resolution Achievable Using A 30khz Multibeam Sonar: Model Predictions And Field Results, John E. Hughes Clarke, James V. Gardner, Mike Torresan, Larry A. Mayer Sep 1998

The Limits Of Spatial Resolution Achievable Using A 30khz Multibeam Sonar: Model Predictions And Field Results, John E. Hughes Clarke, James V. Gardner, Mike Torresan, Larry A. Mayer

Center for Coastal and Ocean Mapping

A Simrad EM300 multibeam sonar was used to attempt to resolve small (-5m high) targets in 450m of water. The targets had previously been surveyed using a deeply towed 59 kHz sidescan sonar. Using multisector active yaw, pitch and roll compensation, together with dynamically altering angular sectors, the sonar is capable of maintaining sounding densities of as tight as 10m spacing in these water depths. This is significantly smaller than the largest dimension of the projected beam footprints (1 6-64m). The observed data suggest that the targets are intermittently resolved. The field results compare well to the output of a …

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The Global Response Of Relativistic Radiation Belt Electrons To The January 1997 Magnetic Cloud, G. D. Reeves, D. N. Baker, R. D. Belian, J. B. Blake, T. E. Cayton, J. F. Fennell, R. H.W. Friedel, M. M. Meier, R. S. Selesnick, Harlan E. Spence Sep 1998

The Global Response Of Relativistic Radiation Belt Electrons To The January 1997 Magnetic Cloud, G. D. Reeves, D. N. Baker, R. D. Belian, J. B. Blake, T. E. Cayton, J. F. Fennell, R. H.W. Friedel, M. M. Meier, R. S. Selesnick, Harlan E. Spence

Physics & Astronomy

In January 1997 a large fleet of NASA and US military satellites provided the most complete observations to date of the changes in >2 MeV electrons during a geomagnetic storm. Observations at geosynchronous orbit revealed a somewhat unusual two-peaked enhancement in relativistic electron fluxes [ Reeves et al., 1998]. In the heart of the radiation belts at L ≈ 4, however, there was a single enhancement followed by a gradual decay. Radial profiles from the POLAR and GPS satellites revealed three distinct phases. (1) In the acceleration phase electron fluxes increased simultaneously at L ≈ 4–6. (2) During the …

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Table Of Contents Volume Nine, Number Four, Fall 1998, Risk Editorial Board Sep 1998

Table Of Contents Volume Nine, Number Four, Fall 1998, Risk Editorial Board

RISK: Health, Safety & Environment (1990-2002)

Table of contents for the journal RISK: Health, Safety & Environment (ISSN: 1073-8673)

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Public Perception Of Risk Management In Environmental Controversies: A U.K. Case Study, Maria Simosi, Peter T. Allen Sep 1998

Public Perception Of Risk Management In Environmental Controversies: A U.K. Case Study, Maria Simosi, Peter T. Allen

RISK: Health, Safety & Environment (1990-2002)

Drs. Simosi and Allen focus on issues arising from an environmental dispute in the U.K. Their case study findings are discussed in the context of existing environmental decision-making procedures in the U.K.

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Contesting Legal Procedures Of Risk Management In Belgium: A Case Study, Tomke Lask Sep 1998

Contesting Legal Procedures Of Risk Management In Belgium: A Case Study, Tomke Lask

RISK: Health, Safety & Environment (1990-2002)

Dr. Lask evaluates legal procedures for dealing with siting problems in Belgium in the context of an actual conflict, and discusses how citizens' dissatisfaction with governmental systems has resulted in increased involvement in environmental issues.

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Reassessing Public Meetings As Participation In Risk Management Decisions, Katherine A. Mccomas, Clifford W. Scherer Sep 1998

Reassessing Public Meetings As Participation In Risk Management Decisions, Katherine A. Mccomas, Clifford W. Scherer

RISK: Health, Safety & Environment (1990-2002)

Using a U.S. case study, Ms. McComas and Dr. Scherer discuss how reliance on public meetings as tools for risk communication in public policy decisions affects relationships between stakeholders and risk managers.

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Mediation In Environmental Conflicts: The Belgian Methodology, Catherine Zwetkoff Sep 1998

Mediation In Environmental Conflicts: The Belgian Methodology, Catherine Zwetkoff

RISK: Health, Safety & Environment (1990-2002)

Dr. Zwetkoff analyzes the effectiveness and feasibility of using traditional ADR techniques to resolve environmental disputes in Belgium.

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Coronal Mass Ejections, Magnetic Clouds, And Relativistic Magnetospheric Electron Events: Istp, D. N. Baker, T. I. Pulkkinen, X. Li, S. G. Kanekal, J. B. Blake, R. S. Selesnick, M. G. Henderson, G. D. Reeves, Harlan E. Spence, G. Rostoker Aug 1998

Coronal Mass Ejections, Magnetic Clouds, And Relativistic Magnetospheric Electron Events: Istp, D. N. Baker, T. I. Pulkkinen, X. Li, S. G. Kanekal, J. B. Blake, R. S. Selesnick, M. G. Henderson, G. D. Reeves, Harlan E. Spence, G. Rostoker

Physics & Astronomy

The role of high-speed solar wind streams in driving relativistic electron acceleration within the Earth's magnetosphere during solar activity minimum conditions has been well documented. The rising phase of the new solar activity cycle (cycle 23) commenced in 1996, and there have recently been a number of coronal mass ejections (CMEs) and related “magnetic clouds” at 1 AU. As these CME/cloud systems interact with the Earth's magnetosphere, some events produce substantial enhancements in the magnetospheric energetic particle population while others do not. This paper compares and contrasts relativistic electron signatures observed by the POLAR, SAMPEX, Highly Elliptical Orbit, and geostationary …

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The Discovery Of Trapped Energetic Electrons In The Outer Cusp, R. B. Sheldon, Harlan E. Spence, J. D. Sullivan, T. A, Fritz, Jiasheng Chen Jun 1998

The Discovery Of Trapped Energetic Electrons In The Outer Cusp, R. B. Sheldon, Harlan E. Spence, J. D. Sullivan, T. A, Fritz, Jiasheng Chen

Physics & Astronomy

We report on the POLAR/CEPPAD discovery of a trapped, 60°<θ<120° pitch angle electron population in the outer cusp (7−9+ Re), whose energetic electron component extends from below 30 keV to ∼2 MeV. Because the time variability in the outer cusp precludes mapping with POLAR, we have carried out test particle simulations using the Tsyganenko 1996 model (T96) to demonstrate the trapping of these energy electrons in the outer cusp region and the resonant frequencies of its trapped motion. We discuss the boundaries and regions of the cusp trap and show that it is analogous to the dipole trap. We show that the phase space densities observed there are equal or greater than the phase space densities observed in the radiation belts at constant magnetic moment, thus allowing the possibility of diffusive filling of the radiation belts from the cusp

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Table Of Contents Volume Nine, Number Three, Summer 1998, Risk Editorial Board Jun 1998

Table Of Contents Volume Nine, Number Three, Summer 1998, Risk Editorial Board

RISK: Health, Safety & Environment (1990-2002)

Table of contents for the journal RISK: Health, Safety & Environment (ISSN: 1073-8673)

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Review Of: Allan Mazur, A Hazardous Inquiry: The Rashomon Effect At Love Canal, Thomas G. Field Jr. Jun 1998

Review Of: Allan Mazur, A Hazardous Inquiry: The Rashomon Effect At Love Canal, Thomas G. Field Jr.

RISK: Health, Safety & Environment (1990-2002)

Review of: Allan Mazur, A Hazardous Inquiry: The Rashomon Effect at Love Canal (Harvard University Press 1998). Abbreviations,, appendices: Chron- ology and The Basics of Toxicology, bibliography, chronology, figures, index, photos, references. LC 97-44639; ISBN 0-674-74833-6 [255+xiv pp. $26.00 Cloth, 79 Garden Street; Cambridge MA 02138.]

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Nuclear Waste And Native America: The Mrs Siting Exercise, M. V. Rajeev Gowda, Doug Easterling Jun 1998

Nuclear Waste And Native America: The Mrs Siting Exercise, M. V. Rajeev Gowda, Doug Easterling

RISK: Health, Safety & Environment (1990-2002)

Drs. Gowda & Easterling provide cross-cultural perspectives on issues of risk perception, equity and policy as they affect nuclear waste storage on Native American sites.

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Review Of: Charles R. Bennett, Risks In The Environment: How To Assess Them, Penny Dean Jun 1998

Review Of: Charles R. Bennett, Risks In The Environment: How To Assess Them, Penny Dean

RISK: Health, Safety & Environment (1990-2002)

Review of: Charles R. Bennett, Risks in the Environment: How to Assess Them (Burloak Publications 1996). Appendices, references for the appendices, prologue. ISBN 0-9680438-0-1 [305 pp. Paper $23.95. 277 Belvenia Rd., Burlington, Ontario.]

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Review Of: Leonard W. Doob, Sustainers And Sustainability, Courtney J. Merrill Jun 1998

Review Of: Leonard W. Doob, Sustainers And Sustainability, Courtney J. Merrill

RISK: Health, Safety & Environment (1990-2002)

Review of: Leonard W. Doob, Sustainers and Sustainability (Praeger Publishers 1995). Bibliography, index, notes. LC 95-7982; ISBN 0-275-95314-9 [167 pp. $52.95 Cloth, .88 Post Road West, Westport, CT 06881.]

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Influence Of Vertical Transport On Free Tropospheric Aerosols Over The Central Usa In Springtime, R. Talbot, Jack E. Dibb, M Loomis May 1998

Influence Of Vertical Transport On Free Tropospheric Aerosols Over The Central Usa In Springtime, R. Talbot, Jack E. Dibb, M Loomis

Earth Sciences

Measurements of the atmospheric aerosol chemical composition during the Subsonic Aircraft: Contrail and Cloud Effects Special Study (SUCCESS) indicate substantial vertical transport of boundary layer aerosol to the free troposphere over the south-central United States during springtime. Mixing ratios of water-soluble aerosol Ca 2+ at 6 - 12 km altitude exhibited a median mixing ratio of 20 pptv, with 15% of the measurements > 100 pptv and a maximum of ! 235 pptv. In air parcels with enhanced Ca 2+, the ratios K+/Ca 2+, Mg2+/Ca 2+, and Na+/Ca 2+ in the bulk aerosol were distinctly characteristic of those in limestone and/or …

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Tropospheric Sulfate Distribution During Success: Contributions From Jet Exhaust And Surface Sources, Jack E. Dibb, R. Talbot, M Loomis May 1998

Tropospheric Sulfate Distribution During Success: Contributions From Jet Exhaust And Surface Sources, Jack E. Dibb, R. Talbot, M Loomis

Earth Sciences

The distribution of SO4= aerosol over the central US during SUCCESS indicates that surface sources of SO4= and SO2 in the western US caused SO4= enhancements up to 10 km altitude. The mean (median) SO4= mixing ratio in the mid- and upper-troposphere increased from 24 (16) pptv over the Pacific ocean to 58 (29) pptv over the central plains. Above 10 km the SO4=mixing ratio was essentially the same in both regions, and also when the geographic classifications were further partitioned into upper tropospheric and lower stratospheric categories …

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Relationship Between Continuous Aerosol Measurements And Firn Core Chemistry Over A 10-Year Period At The South Pole, M H. Bergin, E A. Meyerson, Jack E. Dibb, Paul A. Mayewski Apr 1998

Relationship Between Continuous Aerosol Measurements And Firn Core Chemistry Over A 10-Year Period At The South Pole, M H. Bergin, E A. Meyerson, Jack E. Dibb, Paul A. Mayewski

Earth Sciences

Before ice core chemistry can be used to estimate past atmospheric chemistry it is necessary to establish an unambiguous link between concentrations of chemical species in the air and snow. For the first time a continuous long-term record of aerosol properties (aerosol light scattering coefficient, σsp, and Ångström exponent, å) at the South Pole are compared with the chemical record from a high resolution firn core (∼10 samples per year) covering the period from 1981 to 1991. Seasonal signals in å, associated with winter minima due to coarse mode seasalt and summer maxima due to accumulation mode sulfate …

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Involving Others: Towards An Ethical Concept Of Risk, Christoph Rehmann-Sutter Mar 1998

Involving Others: Towards An Ethical Concept Of Risk, Christoph Rehmann-Sutter

RISK: Health, Safety & Environment (1990-2002)

Dr. Rehman-Sutter argues for a juridical concept of risk as it relates to an ethic of care. He also contrasts his view with traditional economic risk analysis.

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Hunting And Exposure: Estimating Risk And Future Use At Nuclear Production Sites, Jessica Sanchez, Joanna Burger Mar 1998

Hunting And Exposure: Estimating Risk And Future Use At Nuclear Production Sites, Jessica Sanchez, Joanna Burger

RISK: Health, Safety & Environment (1990-2002)

The authors advocate specific criteria for informed decisions about the future use - of contaminated nuclear sites. They also compare the implications of official recommendations for one site with results from a study.

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Table Of Contents Volume Nine, Number Two, Spring 1998, Risk Editorial Board Mar 1998

Table Of Contents Volume Nine, Number Two, Spring 1998, Risk Editorial Board

RISK: Health, Safety & Environment (1990-2002)

Table of contents for the journal RISK: Health, Safety & Environment (ISSN: 1073-8673)

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Through A Lens Darkly--Superfund Spectacles On Public Participation At Brownfield Sites, Kris Wernstedt, Robert Hersh Mar 1998

Through A Lens Darkly--Superfund Spectacles On Public Participation At Brownfield Sites, Kris Wernstedt, Robert Hersh

RISK: Health, Safety & Environment (1990-2002)

The authors discuss the recent trend in brownfield site development against a backdrop of Superfund experience and explore current barriers to public participation.

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The Value Of Preventing Cryptosporidium Contamination, Patricia Kocagil, Nadia Demarteau, Ann Fisher, James S. Shortle Mar 1998

The Value Of Preventing Cryptosporidium Contamination, Patricia Kocagil, Nadia Demarteau, Ann Fisher, James S. Shortle

RISK: Health, Safety & Environment (1990-2002)

The authors evaluate the need for preventing illnesses and fatalities caused by Cryptospiridium contamination of water supplies based on the impacts of recent and likely future outbreaks.

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Ampte/Cce‐Scatha Simultaneous Observations Of Substorm‐Associated Magnetic Fluctuations, S. Ohtani, K. Takahashi, T. Higuchi, A. T. Y. Lui, Harlan E. Spence, J. F. Fennell Mar 1998

Ampte/Cce‐Scatha Simultaneous Observations Of Substorm‐Associated Magnetic Fluctuations, S. Ohtani, K. Takahashi, T. Higuchi, A. T. Y. Lui, Harlan E. Spence, J. F. Fennell

Physics & Astronomy

This study examines substorm-associated magnetic field fluctuations observed by the AMPTE/CCE and SCATHA satellites in the near-Earth tail. Three tail reconfiguration events are selected, one event on August 28, 1986, and two consecutive events on August 30, 1986. The fractal analysis was applied to magnetic field measurements of each satellite. The result indicates that (1) the amplitude of the fluctuation of the north-south magnetic component is larger, though not overwhelmingly, than the amplitudes of the other two components and (2) the magnetic fluctuations do have a characteristic timescale, which is several times the proton gyroperiod. In the examined events the …

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Air-Snow Exchange Of Hno3 And Noy At Summit, Greenland, Jack E. Dibb, R. Talbot, J W. Munger, Daniel J. Jacob, S M. Fan Feb 1998

Air-Snow Exchange Of Hno3 And Noy At Summit, Greenland, Jack E. Dibb, R. Talbot, J W. Munger, Daniel J. Jacob, S M. Fan

Earth Sciences

Ice core records of NO3− deposition to polar glaciers could provide unrivaled information on past photochemical status and N cycling dynamics of the troposphere, if the ice core records could be inverted to yield concentrations of reactive N oxides in the atmosphere at past times. Limited previous investigations at Summit, Greenland, have suggested that this inversion may be difficult, since the levels of HNO3 and aerosol-associated NO3− over the snow are very low in comparison with those of NO3− in the snow. In addition, it appears that some fraction of the NO3 …

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Risk Regulation And The Faces Of Uncertainty, Vern R. Walker Jan 1998

Risk Regulation And The Faces Of Uncertainty, Vern R. Walker

RISK: Health, Safety & Environment (1990-2002)

Dr. Walker addresses the difficulty of regulators' working with potentially inaccurate information and clarifies related aspects of decision making by presenting a taxonomy for the kinds of uncertainty inherent in necessarily incomplete data.

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