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2012

Dartmouth Scholarship

Articles 61 - 69 of 69

Full-Text Articles in Physical Sciences and Mathematics

3,3-Dimethyl-1,2,3,4-Tetra­Hydro­Cyclo­Penta­[B]Indole-1,2-Dione (Bruceolline E), Jason A. Jordon, Jeanese C. Badenock, Gordon W. Gribble, Jerry P. Jasinski, James A. Golen Jan 2012

3,3-Dimethyl-1,2,3,4-Tetra­Hydro­Cyclo­Penta­[B]Indole-1,2-Dione (Bruceolline E), Jason A. Jordon, Jeanese C. Badenock, Gordon W. Gribble, Jerry P. Jasinski, James A. Golen

Dartmouth Scholarship

The title compound, C13H11NO2, crystallizes with two mol­ecules in the asymmetric unit. The crystal packing is stabilized by N—H⋯O hydrogen bonds, which link the mol­ecules into chains along [10], and weak C—H⋯O inter­actions.

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Using Participatory Scenarios To Stimulate Social Learning For Collaborative Sustainable Development, Kris A. Johnson, Genya Dana, Nicholas R. Jordan, Kathy J. Draeger, Anne Kapuscinski Jan 2012

Using Participatory Scenarios To Stimulate Social Learning For Collaborative Sustainable Development, Kris A. Johnson, Genya Dana, Nicholas R. Jordan, Kathy J. Draeger, Anne Kapuscinski

Dartmouth Scholarship

Interdependent human and biophysical systems are highly complex and behave in unpredictable and uncontrollable ways. Social and ecological challenges that emerge from this complexity often defy straightforward solutions, and efforts to address these problems will require not only scientific and technological capabilities but also learning and adaptation. Scenarios are a useful tool for grappling with the uncertainty and complexity of social-ecological challenges because they enable participants to build adaptive capacity through the contemplation of multiple future possibilities. Furthermore, scenarios provide a platform for social learning, which is critical to acting in the face of uncertain, complex, and conflict-laden problems. We …

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Multi-Payload Measurement Of Transverse Velocity Shears In The Topside Ionosphere, E. T. Lundberg, P. M. Kintner, Kristina A. Lynch, M. R. Mella Jan 2012

Multi-Payload Measurement Of Transverse Velocity Shears In The Topside Ionosphere, E. T. Lundberg, P. M. Kintner, Kristina A. Lynch, M. R. Mella

Dartmouth Scholarship

Using a multi-payload sounding rocket mission, we present the first direct measurement of velocity shear in the topside auroral ionosphere. In regions of large, ∼200 mV/m, transient electric fields we directly measure differences in the plasma drift velocity. From these differences, shear frequencies reaching ±6Hz are measured. These directly measured shears are compared with the shear inferred from single payload measurements. It is shown this traditional measurement of shear overestimates the shear frequency by a factor of two for this event, highlighting the importance of the temporal component of near-DC electric field structures. Coincident with these strong fields and shears …

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Multipayload Interferometric Wave Vector Determination Of Auroral Hiss, E. T. Lundberg, P. M. Kintner, S. P. Powell, Kristina A. Lynch Jan 2012

Multipayload Interferometric Wave Vector Determination Of Auroral Hiss, E. T. Lundberg, P. M. Kintner, S. P. Powell, Kristina A. Lynch

Dartmouth Scholarship

We extend traditional, single payload, interferometric techniques to a multiple payload sounding rocket mission, and apply these techniques to measure the parallel and perpendicular wavelength of auroral VLF hiss from 8 kHz–20 kHz. We model the wavelength distribution of auroral hiss as a cone at a fixed angle with respect to the magnetic field that is isotropically distributed in the perpendicular plane. We apply this model to calculate the interferometric observables, coherency and phase, for a sounding rocket mission whose wave electric field receivers are on payloads that are separated 2–3 km along the magnetic field and 55–200 m across …

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Electron Temperature In The Cusp As Measured With The Scifer-2 Sounding Rocket, E. J. Lund, M. R. Lessard, F. Sigernes, D. A. Lorentzen, K. Oksavik, P. M. Kintner, Kristina A. Lynch, D. H. Huang, B. C. Zhang, H. G. Yang, Y. Ogawa Jan 2012

Electron Temperature In The Cusp As Measured With The Scifer-2 Sounding Rocket, E. J. Lund, M. R. Lessard, F. Sigernes, D. A. Lorentzen, K. Oksavik, P. M. Kintner, Kristina A. Lynch, D. H. Huang, B. C. Zhang, H. G. Yang, Y. Ogawa

Dartmouth Scholarship

It is expected that energy deposited by soft auroral electron precipitation in the ionosphere should result in heating of ionospheric electrons in that location, and this heating is an important step in the ion outflow process. We present coordinated observations from the SCIFER-2 sounding rocket in the cusp region overflying optical observing sites in Svalbard. The rocket payload included a sensor which is designed to measure the temperature of thermal electrons. We show that elevated electron temperatures measured in situ are correlated with electron precipitation as inferred from auroral emissions during the 60–120 s preceding the passage of the rocket. …

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Comparing Vhf Coherent Scatter From The Radar Aurora With Incoherent Scatter And All-Sky Auroral Imagery, D. Hysell, R. Miceli, J. Munk, D. Hampton, C. Heinselman, M. Nicolls, S. Powell, Kristina A. Lynch, M. Lessard Jan 2012

Comparing Vhf Coherent Scatter From The Radar Aurora With Incoherent Scatter And All-Sky Auroral Imagery, D. Hysell, R. Miceli, J. Munk, D. Hampton, C. Heinselman, M. Nicolls, S. Powell, Kristina A. Lynch, M. Lessard

Dartmouth Scholarship

VHF coherent scatter radar observations of an auroral substorm over Alaska are analyzed in the context of multibeam incoherent scatter plasma density and drifts data and green-line all-sky optical imagery. Coherent scatter arises from Farley Buneman waves which are excited in theEregion whenever the convection electric field is greater than about 20 mV/m. Aperture synthesis radar imaging and other aspects of the methodology facilitate the precise spatial registration of the coherent scatter with coincident optical and incoherent scatter radar measurements. Discrete auroral arcs were found to separate diffuse regions of coherent backscatter and, sometimes, to align with the …

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Structure And Dynamics Of The Nightside Poleward Boundary: Sounding Rocket And Ground-Based Observations Of Auroral Electron Precipitation In A Rayed Curtain, Kristina A. Lynch, D. Hampton, M. Mella, Bingzheng Zhang, H. Dahlgren, M. Disbrow, P. M. Kintner, M. Lessard, E. Lundberg, H. C. Stenbaek-Nielsen Jan 2012

Structure And Dynamics Of The Nightside Poleward Boundary: Sounding Rocket And Ground-Based Observations Of Auroral Electron Precipitation In A Rayed Curtain, Kristina A. Lynch, D. Hampton, M. Mella, Bingzheng Zhang, H. Dahlgren, M. Disbrow, P. M. Kintner, M. Lessard, E. Lundberg, H. C. Stenbaek-Nielsen

Dartmouth Scholarship

The Cascades2 auroral sounding rocket provides a case study for comparing multipoint in situ ionospheric observations of a nightside auroral poleward boundary intensification with ground-based optical observations of the same event. Cascades2 was launched northward from Poker Flat Alaska on 20 March 2009 at 11:04 UT. The 13 min flight reached an apogee of 564 km over the northern coast of Alaska. The experiment included a five-payload array of in situ instrumentation, ground cameras at three different points under the trajectory, multiple ground magnetometers, the Poker Flat Incoherent Scatter Radar (PFISR) radar, and the Time History of Events and Macroscale …

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A Reverberation Lag For The High-Ionization Component Of The Broad-Line Region In The Narrow-Line Seyfert 1 Mrk 335, C. J. Grier, B. M. Peterson, R. W. Pogge, K. D. Denney, M. C. Bentz, Paul Martini, S. G. Sergeev, S. Kaspi, Y. Zu, C. S. Kochanek, B. J. Shappee, C. Araya Salvo, T G. Beatty, J. C. Bird, D. J. Bord, G. A. Borman, X. Che, C. Chen Jan 2012

A Reverberation Lag For The High-Ionization Component Of The Broad-Line Region In The Narrow-Line Seyfert 1 Mrk 335, C. J. Grier, B. M. Peterson, R. W. Pogge, K. D. Denney, M. C. Bentz, Paul Martini, S. G. Sergeev, S. Kaspi, Y. Zu, C. S. Kochanek, B. J. Shappee, C. Araya Salvo, T G. Beatty, J. C. Bird, D. J. Bord, G. A. Borman, X. Che, C. Chen

Dartmouth Scholarship

We present the first results from a detailed analysis of photometric and spectrophotometric data on the narrow-line Seyfert 1 (NLS1) galaxy Mrk 335, collected over a 120 day span in the fall of 2010. From these data we measure the lag in the He ii λ 4686 broad emission line relative to the optical continuum to be 2.7 °æ 0.6 days and the lag in the Hβλ 4861 broad emission line to be 13.9 °æ 0.9 days. Combined with the line width, the He ii lag yields a black hole mass MBH = (2. 6 °æ 0. 8) °ø 107M …

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Effects Of Network Trace Sampling Methods On Privacy And Utility Metrics, Phillip A. Fazio, Keren Tan, David Kotz Jan 2012

Effects Of Network Trace Sampling Methods On Privacy And Utility Metrics, Phillip A. Fazio, Keren Tan, David Kotz

Dartmouth Scholarship

Researchers choosing to share wireless-network traces with colleagues must first anonymize sensitive information, trading off the removal of information in the interest of identity protection and the preservation of useful data within the trace. While several metrics exist to quantify this privacy-utility tradeoff, they are often computationally expensive. Computing these metrics using a \emphsample\/ of the trace could potentially save precious time. In this paper, we examine several sampling methods to discover their effects on measurement of the privacy-utility tradeoff when anonymizing network traces. We tested the relative accuracy of several packet and flow-sampling methods on existing privacy and utility …

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