Susan E. H. Sakimoto

GEST Associate Research Scientist

Geodynamics Branch, NASA/Goddard Space Flight Center,

curiousier and curiousier...picture of lava

" checking the lava plumbing system..."

Email : Susan.E.Sakimoto.1@gsfc.nasa.gov

Education:

Whitman College

M.A. Earth and Planetary Sciences, Johns Hopkins University, 1991

Ph.D. Earth and Planetary Sciences (Geophysics), Johns Hopkins University, January, 1995

Thesis Advisor: Maria T. Zuber

Research Interests:

Modeling geophysical processes in terrestrial volcanism and planetary geology and geophysics, specifically:

Lava flow and cooling with analytic and computational fluid dynamics approaches
Hydrovolcanism--morphology of landforms and eruption modeling
Topographic expression and emplacement of volcanic and impact landforms

Research Experience

2000-present   GEST Associate Research Scientist, NASA/Goddard
1999-2000      USRA Associate Research Scientist II, NASA/Goddard
1997-1999      USRA Assistant Research Scientist, NASA/Goddard
1995-1997      National Research Council Resident Research Associate, NASA/Goddard
1990-1994     NASA Graduate Research Fellow, Johns Hopkins University
1989-1990     Gilman Research Fellow, Johns Hopkins University

Teaching Experience

1999-2001 Faculty member for KECK Geology Consortium
MARS 2000 Sophomore Research Project at NASA/Goddard Space Flight Center

1998-present     Instructor in Earth and Space Sciences, Maryland Space Grant Consortium and the
                         Johns Hopkins School of Professional Studies in Business & Education, Masters of Science in Education Program
                         Understanding and Teaching the Solar System (for Secondary Inservice Science Teachers)
                                      (Spring Semester 1998-present) click HERE for registration and class information)

1995 Instructor, Space Sciences, Maryland Space Grant Consortium, Johns Hopkins University
Space Sciences (Team-taught course for Inservice Teachers)

1989-1993        Teaching Assistant, Johns Hopkins University, Earth and Planetary Sciences Department
                         Guided Tour of the Planets,   (Undergraduate Distribution Course)
                         Geodynamics   (Graduate Course)
                         Nature of the Solid Earth    (Graduate Course, TA for two years)

Professional Involvement and Community Service

Chair, Geological Society of America Planetary Geology Division (click HERE to visit the division web page)
Local Host and Organizer, Fourteenth KECK Research Symposium in Geology, April 2001, NASA/Goddard
Member, AGU, GSA, IAVCEI, Sigma Xi
Lunar and Planetary Science Conference Program Committee, 1999, 2001
Geological Society of America Joint Technical Program Committee, 2000, 2001, 2002
NASA/Goddard 921/926 Seminar Series Coordinator
Science Advisor, Earth and Sky Radio Series
Curricullum Design Committee 1998-1999, Maryland Space Grant Consortium and the Johns HopkinsUniversity Masters of Science in Education Program in Earth and Space Sciences
Reviewer, assorted professional journals, NASA (MDAP, PG&G) and NSF (Petrology & Geochemistry) programs

Recent Stuff:

In press (as of 11/2001)

S.E.H. Sakimoto

Frey, H., K.M. Shockey, E.L. Frey, J.H. Roark, S.E.H. Sakimoto, Ancient Lowlands on Mars, in press, Geophysical Research Letters.

A S.E.H. Sakimoto and T.K.P. Gregg paper on channeled lava flows is out in JGR-Solid Earth, and the link to it is: JGR-Solid Earth Link to PDF File. If you do not have a JGR subscription with online access, the full reference is in the recent publications list below.
The Mars 2000 KECK Sophomore Research Project held during summer 2000 in the Geodynamics Branch went well. Follow the link to get a project description and pictures.
Our (Garvin et al.) paper on Topographic Evidence for Geologically Recent Near-Polar Volcanism on Mars is out in the June 2000 ICARUS. Click link to get a pdf file.
Our paper on North Polar Region Craterforms on Mars came out in the April 2000 ICARUS issue. Click link to get a pdf file.
Recent results on the Mars Borealis Volcanic field (near the north pole) were presented at the Second International Conference on Mars Polar Science and Exploration. in Reykjavik, Iceland August 21-25th, 2000. Get a copy of the abstract in pdf form by following this link: Mars Polar Conference Abstract.
Have you visited the Geodynamics Branch and wanted to take home Jim Roark's data visualization software for MOLA data? Now you can... see this link: Interactive Graphcs To ols for MOLA data

Research Descriptions

(Research is supported by grants from NSF Earth Sciences Division, NASA Mars Data Analysis Program and MOLA Science Team Mission funds.)

Near-polar volcanism on Mars

We have been studying polar volcanic features on Mars with the goal of understanding possible volcano-ice or volcano-water (hydromagmatic) features on Mars. Our primary measurement tool is the Mars Orbiter Laser Alimeter. We compare these features to terrestrial volcanic and hydromagmatic features, and model a range of possible eruption processes. Preliminary results for te feature below are reported in the June issue of Icarus Topographic Evidence for Geologically Recent Near-Polar Volcanism on Mars.Recent results for the whole Mars Borealis Volcanic field were presented at the Second International Conference on Mars Polar Science and Exploration. You can get a copy of the abstract in pdf form by following this link: Mars Polar Conference Abstract.

Perspective view of a Mars Cratered Cone

Perspective view of a Mars Cratered Cone. This is a high resolution Viking Orbiter Image over a lower resolution Mars DigitalImage Mosaic draped over a MOLA-derived Digital Elevation Map. The bright deposits are frost on the volcano flank and crater interior.

Emplacement and cooling of lava tubes, domes, and channels

We use analytic and computational fluid dynamics methods to model the flow and cooling of volcanic flows on the terrestrial planets. Increasingly physical realistic models are constructed by coupling the heat and fluid flow solutions with a variety of rheologies to model eruption in different planetary environments. We try to increase our understanding of the relationships between flow processes, composition, and morphology for lava tubes, domes, channels, and surface flows on the Earth, Venus, and Mars. Current work includes temperature-dependent non-Newtonian lava tube flow, Bingham channel flow, and temperature-dependent models of previous laboratory lava flow analogs.

Venus volcanic domes

"Venus volcanic domes (D=20 km) and lava plains near Alpha Regio"

Volcanic resurfacing and planetary thermal evolution.

Volcanism is a major process in planetary resurfacing and cooling, and a central issue in planetary volcanism is the rates at which lava was erupted and emplaced, and how much heat was associated with the eruption. Large areas of the surfaces of Earth, Venus, and Mars are thought to be covered by basaltic plains volcanism, and there are several basic issues that can be addressed by modeling the emplacement and cooling of these lavas: How far and how fast can the lavas travel in different cooling regimes? Are numerous eruptive centers required for the observed distribution? What was the heat flux from the flows to the atmosphere and how long was it sustained? To what extent are the different volcanic plains styles controlled by the eruptive center locations and sizes, and to what extent are they controlled by different cooling rates of the lavas after eruption? What constraints on the planetary resurfacing and cooling rates can be inferred from the lava eruption rates?

Since lava tube flow is a large component of basaltic plains and shield volcanism, we can assess the flow rates and maximum flow distances for different tube sizes and lava compositions in different planetary cooling environments. We use these--combined with estimations of the minimum number of tube-fed flows necessary to resurface a region from a single or multiple eruptive centers--in order to constrain the resurfacing and heat flux rates for regional and planetary thermal evolution.

PuuOo tube system skylight

"PuuOo tube system skylight at 2450', 1995 Kilauea eruption."

Rheologic models for temperature-dependent and non-Newtonian lava.

The known dependence of the cooling lava rheology on both temperature and shear rate has often challenged the accuracy of lava flow modeling. Frequently, either or both of the temperature or the shear rate dependencies is neglected because of either lack of rheological data or simplicity requirements in reaching a solution. However, recent advances in computational solutions have allowed coupled heat and velocity lava flow models, which can handle a variety of complex rheologies. This work is a compilation of existing field, laboratory and theoretical work on the behavior of cooling basaltic lava into a working model of a shear and temperature dependent basalt rheology. ower law flow curves are fit to field and laboratory data for basaltic lava for temperatures ranging from superliquidus to 55% solid. Theoretical constraints are used to determine the general fit parameters where data is unavailable. Both Kilauea-type basalts and the cooler Etna-type basalts are considered. A three-part fit to the data is used to cover the three general regimes of behavior a cooling lava is likely to pass through. For superliquidus to approximately 20% crystals, a standard Newtonian fit with an exponential temperature dependence is used. For 20% to 55% volume crystals, a (shear-rate dependent) power law is fit to the data with a linear temperature dependence for both the power law exponent and the power law coefficient. For 55% volume crystals and higher, the melts is assumed to be crystal-rich enough to behave as an effective solid. We find that the temperature dependence of the model produces flow field results significntly different from isothermal Newtonian models, and that for lavas erupted with high crystallinities the shear rate dependence is as important as the temperature dependence.

Computational Fluid Dynamics analysis of planetary lava flows

This work is part of a study modeling the flow and cooling of volcanic flows on the terrestrial planets in order to better understand both lava flow processes and their role in the thermal evolution of the interiors and atmospheres of the terrestrial planets. For example, we used the CFD program NEKTON (product of Fluent Inc.)to calculate the full three dimensional solution for Bingham flow down a slope and check some of the simplyifing assumptions in a previous analytic analysis that is often used for estimating rheology and flow rate in planetary lava flows. We found that the initial assumptions are problematic--the assumption of a parabolic flow profile along with an assumed criteria for levee depth actually implicitly assumes the relationship between flow width, yield strength, and levee width, rather than deriving it. In the full three-dimensional flow solution (figure 1), the shear stress on the levee walls from the channel prevent stationary levees from forming unless the levee has either a substantially higher viscosity or yield strength than the channel. For example, the CFD solution for Mauna Loa 1942 flow with the parabolic flow cross section and rheology assumed by Hulme (1974) shows that most of the predicted stationary levee area is moving downstream at up to 1/6th of the central channel flow speed (Sakimoto et al., 1996), and that the Hulme method overestimates the 3-D solution's flow rate by a factor of five. Other CFD analyses of lava flows in progress include lava tube flow and lava dome extrusion and emplacement.

Z velocity component contour plot

Figure 1. CFD results for the velocity in the downhill direction for a single Bingham fluid with a parabolic cross-section

Planetary mantle flow and topographic responses.

Previous work includes viscous convective flow models of the effects the subduction of a buoyant ridge would have on the overlying plate topography and volcanism (Sakimoto and Bills, 1994, EOS Trans.).

Instrument development:

The Laser Velocity/Range Finder for Active Lava Flows is a new non-coherent laser instrument approach using a fiber optic Fabry Perot filter to measure the doppler shift of the returned signal. The goal is a footprint resolution of 1-3 cm and a velocity resolution of 1 cm/s. The resulting lava velocity profiles will be used to measure determine lava flow properties that cannot be measured directly in the field, and are essential for modeling emplacement and cooling of lava on the terrestrial planets. The PI is Pamela Millar of the Laser Remote Sensing Branch, and the Co-I is Susan Sakimoto. 1996 Summer student help is provided by Gretchen Schroeder from Bucknell University. J. Kauahikaua of the Hawaii Volcano Observatory is providing field testing advice. The Laser Velocity/Range Finder for Active Lava Flows is funded by the NASA/Goddard Director's Discretionary Fund.

Susan taking laser ranging measurements

"Laser ranger measurements at a lava tube skylight"

Follow this link for information on my sidekicks: Jackie and Katrina and a link to the OTHER Dr. Sakimoto at NASA/HQ

Recent Publications:

Burr, D. M., A.S. McEwen, S.E.H. Sakimoto, Recent aqueous floods from the Cerberus Fossae, Mars, in press, Geophysical Research Letters.

Frey, H., K.M. Shockey, E.L. Frey, J.H. Roark, S.E.H. Sakimoto, Ancient Lowlands on Mars, in press, Geophysical Research Letters.

Sakimoto, S.E.H. and T.K.P. Gregg, 2001, Channeled flow: Analytic solutions, laboratory experiments, and applications to lava flows, Journal of Geophysical ResearchóSolid Earth, Vol. 106., No. B5 (May), p. 8629-8648.

Garvin, J.B., S.E.H. Sakimoto, J.J. Frawley, and C.C. Schnetzler, North Polar Region Craterforms on Mars: Geometric Characteristics from the Mars Orbiter Laser Altimeter, Icarus, 144 (April), 329-352, 2000.
(click HERE for pdf version of this reprint)

Garvin, J.B., S.E.H. Sakimoto, J.J. Frawley, C.C. Schnetzler, and H.M. Wright, Topographic Evidence for geologically recent near-polar volcanism on Mars, Icarus, 145 (June), 648-652, 2000.
(click HERE for pdf version of this reprint)

Grosfils, E.B., J.C. Aubele, L.S. Crumpler, T.K.P. Gregg, and S.E.H. Sakimoto, 2000, Volcanism on Earth's seafloor and Venus, in Environmental Effects on Volcanic Eruptions: From Deep Oceans to Deep Space, edited by J.R. Zimbelman, and T.K.P. Gregg, Plenum Publishing, New York, pp. 266.

Barlow, N.G., J.M. Boyce, F.M. Costard, R.A. Craddock, J.B. Garvin, S.E.H. Sakimoto, R.O. Kuzmin, D.J. Roddy, L.A. Soderblom, 2000, Standardizing the nomenclature of martian impact crater ejecta morphologies, in press, Journal of Geophysical Research-Planets.

Sakimoto, S.E.H., H.V. Frey, J.B. Garvin, and J.H. Roark, 1999, Topography, roughness, layering, and slope properties of the Medusae Fossae Formation from Mars Orbiter Laser Altimeter (MOLA) and Mars Orbiter Camera (MOC) data, J. Geophys. Res., 104 (E10), 24141-24154.

Frey, H., S. Sakimoto, and J. Roark, 1999, Discovery of a 450 km diameter, multi-ring basin on Mars through analysis of MOLA topographic data, Geophysical Research Letters, V26 (no. 12), 1657-1660

Sakimoto, S.E.H., and M.T. Zuber, 1998, Flow and convective cooling in lava tubes , Journal of Geophysical Research?Solid Earth, 103 (B11), 27465ó27487.

Frey, H.V., S.E.H. Sakimoto, and J.H. Roark, 1998, The MOLA topographic signature at the crustal dichotomy boundary zone on Mars, Geophys. Res. Letts., 25 (24), 4409-4412.

Sakimoto, S.E.H., Baloga, S.M., and J. Crisp, 1997, Eruption constraints on tube-fed planetary lava flows, Journal of Geophysical Research-Planets, 102 (E3), 6597-6613.

Sakimoto, S. E. H. and M. T. Zuber, 1995, The spreading of variable viscosity axisymmetric radial gravity currents: applications to the emplacement of Venusian 'pancake' domes, Journal of Fluid Mechanics, 301, 65-77.

Sakimoto, S. E. H. and M. T. Zuber, 1995, Effects of planetary thermal structure on the ascent and cooling of magma on Venus. Journal of Volcanology and Geothermal Research, 64, 53-60.

Belt, E.S., S.E.H. Sakimoto, and B.W. Rockwell, 1992, A drainage diversion hypothesis for the origin of widespread coal beds in the Williston Basin; Examples from Paleocene strata, eastern Montana, in: Coal Geology of Montana, M.A. Sholes and S. Vuke-Foster, editors, Montana Bureau of Mines and Geology Special Publication 102, Butte, MT.

Selected Recent Abstracts: (§= graduate student author; * =undergraduate author)

Sakimoto, S.E.H., S.J. Riedel, D. Burr, Geologically Recent Martian Volcanism and Flooding in Elysium Planitia and Cerberus Rupes: Plains Style Eruptions and Related Water Release? Geological Society of America Meeting, November 5-8, 2001.

Frey, H.V., K.M. Shockey, J. Roark, E.L. Frey, and S.E.H. Sakimoto, Ancient Lowlands on Mars: Buried Impact Basins and the Age of the Crustal Dichotomy, Geological Society of America Meeting, November 5-8, 2001.

Sakimoto, S. E. H. , J. B. Garvin, B. A. Bradley, M. Wong, and J. J. Frawley, Small martian north polar volcanoes: Topographic implications for eruption styles, LPSC XXXII, CDROM, abstract #1808, 2001.

§Wong, M.P., S.E.H. Sakimoto, and J.B. Garvin, MOLA Topography of small volcanoes in Tempe Terra and Ceraunius Fossae, Mars: Implications for eruptive style, LPSC XXXII, CDROM, abstract #1563, 2001.

§Bradley, B. A., and S.E.H. Sakimoto, Interactions of the Medusae Fossae Formation (MFF), Fluvial Channels, and the Dichotomy Boundary Southeast of Nicholson Crater, Mars, LPSC XXXII, CDROM, abstract #1335, 2001.

Grosfils, E.B. and S.E.H. Sakimoto, Topographic constraints on magma reservoir volume and depth for small near-polar volcanoes in the northern plains of Mars, LPSC XXXII, CDROM, abstract #1111, 2001.

Gregg, T.K.P., D.A. Crown, and S.E.H. Sakimoto, Evolution and Erosion of Tyrrhena and Hadriaca Paterae, Mars: New Insights from MOC and MOLA, LPSC XXXII, CDROM, abstract #1628, 2001.

Frey, H.V., E.L. Frey, S.E.H. Sakimoto, K. Shockey, and J. Roark, A Very Large Population of Likely Buried Impact Basins in the Northern Lowlands of Mars Revealed by MOLA Data, LPSC XXXII, CDROM, abstract #1680, 2001.

Grosfils E.B., S.E.H. Sakimoto, C.V. Mendelson and J.E. Bleacher, The KECK "Mars 2000" Project: Using Mars Orbiter Laser Altimeter data to assess geological processes and regional stratigraphy near Orcus Patera and Marte Valles on Mars, LPSC XXXII, CDROM, abstract #1110, 2001.

*Carter, B.L., H. Frey, S.E.H. Sakimoto, and J. Roark Constraints on Gusev Basin Infill from the Mars Orbiter Laser Altimeter (MOLA) Topography, LPSC XXXII, CDROM, abstract #2042, 2001.

*Riedel, S. J., S.E.H. Sakimoto, B. A. Bradley, and A. DeWet, Lava tube flow models at Alba Patera, Mars: Topographic constraints on eruption rates, LPSC XXXII, CDROM, abstract #1954, 2001.

*Yoburn, J.B., R. Yazzie, E.B. Grosfils, S.E.H. Sakimoto, C.V. Mendelson and J.E. Bleacher, Age Relationships and chronology for the Orcus Patera region of Mars, LPSC XXXII, CDROM, abstract #1077, 2001.

*Silver M.H., A.S. Gendaszek, E B. Grosfils, S.E.H. Sakimoto, C.V. Mendelson, and J.E. Bleacher , Wrinkle ridge formation north of Orcus Patera, Mars, LPSC XXXII, CDROM, abstract #1043, 2001.

*Therkelsen J. P., S. S. Santiago, E. B. Grosfils, S. E. H. Sakimoto, C.V. Mendelson, J. E. Bleacher , Eruption Constraints for a young channelized lava flow, Marte Valles, Mars, LPSC XXXII, CDROM, abstract #1112, 2001.

*Moller, S.C., K.E. Poulter, E.B. Grosfils, S.E.H. Sakimoto, C.V. Mendelson, and J.E. Bleacher, Morphology of the Marte Valles channel system, Mars, LPSC XXXII, CDROM, abstract #1382, 2001.

*van der Kolk D.A., K.L. Tribbett, E.B. Grosfils, S.E.H. Sakimoto, C.V. Mendelson and J.E. Bleacher, Orcus Patera, Mars: Impact crater or volcanic caldera?, LPSC XXXII, CDROM, abstract #1085, 2001.

§Bradley, B. A., and S. E. H. Sakimoto, Investigation of parallel valleys in the Medusae Fossae Formation south of Marte Valles, Mars, Geological Society of America Meeting, November 13-16, 2000.

Grosfils, E. B., S.E.H. Sakimoto, C.V. Mendelson, and J.E. ?Bleacher, The Mars 2000 Sophomore Keck Project: Using Mars Global Surveyor and Viking data to assess the geology of the Cerberus Plains region near Orcus Patera, Geological Society of America Meeting, November 13-16, 2000.

Sakimoto, S. E. H., T.K.P. Gregg, and D.A. Crown, MOLA Topography of the Tyrrhena Patera lava flow field, Mars: Initial results and implications for lava flow emplacement, Geological Society of America Meeting, November 13-16, 2000.

Zimbelman, J. R., S. E. H. Sakimoto, and H. Frey, Evidence for a Fluvial Contribution to the Complex Story of the Medusae Fossae Formation on Mars, Geological Society of America Meeting, November 13-16, 2000.

Sakimoto, S.E.H., J.B. Garvin, M. §Wong, and H. ?Wright, Topography of small volcanoes at the margin of the Mars north polar cap, 2nd Int. Conf. on Mars Polar Science and Exploration, Reykjavik, Iceland, Aug. 21-25, 2000.

Sakimoto, S E H, H Frey, M §Wong, MOLA Topography of Large Volcanic Channels or Tubes from Syrtis Major into Isidis Basin, Mars, Spring AGU, 2000.

*Bleacher, J.E., J.B. Garvin, and S.E.H. Sakimoto, South polar pedestal craters on Mars: Implications for the south polar erosional regimes from Mars Orbiter Laser Altimeter (MOLA) data, LPSC XXXI, Houston, TX, CDROM, Abstract # 1964, 2000.

*Bradley, B.A., E.B. Grosfils, and S.E.H. Sakimoto, Boundaries and stratigraphy of the Medusae Fossae Formation and Elysium Basin materials using Mars Orbiter Laser Altimeter (MOLA) data, LPSC XXXI, Houston, TX, CDROM, Abstract # 2055, 2000.

Garvin, J.B., S.E.H. Sakimoto, J.J. Frawley, and C. Schnetzler, Global geometric properties of martian impact craters: An assessment from Mars Orbiter Laser Altimeter (MOLA) Digital Elevation models, LPSC XXXI, Houston, TX, CDROM, Abstract # 1619, 2000.

Gregg, T.K.P., and S.E.H. Sakimoto, Marte Valles lava channel flow rates and rheology from MOC and MOLA data, LPSC XXXI, Houston, TX, CDROM, Abstract # 1758, 2000.

§Matias, A., J.B. Garvin, and S.E.H. Sakimoto, Mid-latitude simple to transitional impact craters on Mars: From Viking images and Mars Orbiter Laser Altimeter (MOLA) topographic data, LPSC XXXI, Houston, TX, CDROM, Abstract # 1787, 2000.

Sakimoto, S.E.H., J.B. Garvin, and H. §Wright, Topography of small volcanic edifices in the Mars northern polar region from Mars Orbiter Laser Altimeter Observations, LPSC XXXI, Houston, TX, CDROM, #1971, 2000.

§Wright, H.M., S.E.H. Sakimoto, and J.B. Garvin, Morphology of some small Mars north polar volcanic edifices from Viking images and MOLA topography, LPSC XXI, Houston, TX, CDROM, Abstract # 1894, 2000.

Sakimoto, S.E.H., H.V. Frey, and J.R. Zimbelman, Medusae Fossae Formation, Mars: MOLA topographic constraints on photogeologic interpretations of complex materials, Geological Society of America October 1999 Denver meeting, October 25-28, 1999.

Sakimoto, S.E.H., and T.K.P. Gregg, Lava flow emplacement in tubes, channels, and sheets, EOS Trans. AGU, vol. 80, p. F1100, 1999 (invited).

Sakimoto, S.E.H. and J.B.Garvin, Martian Polar Impact Craters: A Preliminary Assessment using Mars Orbiter Laser Altimeter (MOLA), 5th International Conference on Mars, Pasadena, CA, July 19-23, 1999.

Garvin, J.B., S.E.H. Sakimoto, C. Schnetzler, and J.J. Frawley, Global Geometric Properties of Martian Impact Craters: A Preliminary Assessment using Mars Orbiter Laser Altimeter (MOLA) Topography, 5th International Conference on Mars, Pasadena, CA, July 19-23, 1999.

Sakimoto, S.E.H., and J.B. Garvin, Topography of Impact Structures on the Northern Polar Cap of Mars, LPSC XXX Houston, TX, March 15-19th , CDROM, Abstract #1993, 1999.

Garvin, J.B. and S.E.H. Sakimoto, Near-Polar Cratered Cones on Mars: MOLA Measurements and Implications for Volcanic Origins, LPSC XXX, Houston, TX, March 15-19th , CDROM, Abstract #1492, 1999.

§Matias, A., J.B. Garvin, and S.E.H. Sakimoto, Mid-Latitude vs. Polar-Latitude Transitional Impact Craters: Geometric Properties from Mars Orbiter Laser Altimeter, LPSC XXX Houston, TX, March 15-19th , CDROM, Abstract # 2008, 1999.

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