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2016

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Articles 1 - 30 of 86

Full-Text Articles in Physical Sciences and Mathematics

Wave Motion Induced By Turbulent Shear Flows Over Growing Stokes Waves, Shahrdad Sajjadi, Serena Robertson, Rebecca Harvey, Mary Brown Dec 2016

Wave Motion Induced By Turbulent Shear Flows Over Growing Stokes Waves, Shahrdad Sajjadi, Serena Robertson, Rebecca Harvey, Mary Brown

Publications

The recent analytical of multi-layer analyses proposed by Sajjadi et al. (J Eng Math 84:73, 2014) (SHD14 therein) is solved numerically for atmospheric turbulent shear flows blowing over growing (or unsteady) Stokes (bimodal) water waves, of low-to-moderate steepness. For unsteady surface waves, the amplitude a(t)∝ekcita(t)∝ekcit, where kcikci is the wave growth factor, k is the wavenumber, and cici is the complex part of the wave phase speed, and thus, the waves begin to grow as more energy is transferred to them by the wind. This will then display the critical height to a point, where ...


Quantifying Gravity Wave Momentum Fluxes With Mesosphere Temperature Mappers And Correlative Instrumentation, David C. Fritts, Pierre-Dominique Pautet, Katrina Bossert, Michael J. Taylor, Bifford P. Williams, Hiroyuki Iimura, Tao Yuan, Nicholas J. Mitchell, Gunter Stober Dec 2016

Quantifying Gravity Wave Momentum Fluxes With Mesosphere Temperature Mappers And Correlative Instrumentation, David C. Fritts, Pierre-Dominique Pautet, Katrina Bossert, Michael J. Taylor, Bifford P. Williams, Hiroyuki Iimura, Tao Yuan, Nicholas J. Mitchell, Gunter Stober

Publications

An Advanced Mesosphere Temperature Mapper and other instruments at the Arctic Lidar Observatory for Middle Atmosphere Research in Norway (69.3°N) and at Logan and Bear Lake Observatory in Utah (42°N) are used to demonstrate a new method for quantifying gravity wave (GW) pseudo-momentum fluxes accompanying spatially and temporally localized GW packets. The method improves on previous airglow techniques by employing direct characterization of the GW temperature perturbations averaged over the OH airglow layer and correlative wind and temperature measurements to define the intrinsic GW properties with high confidence. These methods are applied to two events, each of ...


Ionospheric Signatures Of Gravity Waves Produced By The 2004 Sumatra And 2011 Tohoku Tsunamis: A Modeling Study, Michael P. Hickey, Yonghui Yu, Wenqing Wang Dec 2016

Ionospheric Signatures Of Gravity Waves Produced By The 2004 Sumatra And 2011 Tohoku Tsunamis: A Modeling Study, Michael P. Hickey, Yonghui Yu, Wenqing Wang

Publications

Ionospheric fluctuations inferred from observations of total electron content have previously been attributed to tsunamis and have confirmed the strong coupling between Earth’s ocean and ionosphere via atmospheric gravity waves (AGWs). To further advance our understanding of this wave coupling process we employ a linear full-wave model and a nonlinear time-dependent model to examine the ionospheric response to the AGW perturbations induced by the 2004 Sumatra and the 2011 Tohoku tsunamis. In the 2004 case, our modeling analyses reveal that one component of the propagating AGWs becomes dynamically unstable in the E-region ionosphere at a range exceeding 2000 km ...


The Rate Of Binary Black Hole Mergers Inferred From Advanced Ligo Observations Surrounding Gw150914, B. P. Abbott, K. Gill, B. Hughey, M. J. Szczepańczyk, M. Zanolin, Et Al. Dec 2016

The Rate Of Binary Black Hole Mergers Inferred From Advanced Ligo Observations Surrounding Gw150914, B. P. Abbott, K. Gill, B. Hughey, M. J. Szczepańczyk, M. Zanolin, Et Al.

Publications

A transient gravitational-wave signal, GW150914, was identified in the twin Advanced LIGO detectors on 2015 September 2015 at 09:50:45 UTC. To assess the implications of this discovery, the detectors remained in operation with unchanged configurations over a period of 39 days around the time of the signal. At the detection statistic threshold corresponding to that observed for GW150914, our search of the 16 days of simultaneous two-detector observational data is estimated to have a false-alarm rate (FAR) of


Tests Of Lorentz Symmetry In The Gravitational Sector, Aurélien Hees, Quentin G. Bailey, Adrien Bourgoin, Hélène Pihan-Le Bars, Christine Guerlin, Christophe Le Poncin-Lafitte Dec 2016

Tests Of Lorentz Symmetry In The Gravitational Sector, Aurélien Hees, Quentin G. Bailey, Adrien Bourgoin, Hélène Pihan-Le Bars, Christine Guerlin, Christophe Le Poncin-Lafitte

Publications

Lorentz symmetry is one of the pillars of both General Relativity and the Standard Model of particle physics. Motivated by ideas about quantum gravity, unification theories and violations of CPT symmetry, a significant effort has been put the last decades into testing Lorentz symmetry. This review focuses on Lorentz symmetry tests performed in the gravitational sector. We briefly review the basics of the pure gravitational sector of the Standard-Model Extension (SME) framework, a formalism developed in order to systematically parametrize hypothetical violations of the Lorentz invariance. Furthermore, we discuss the latest constraints obtained within this formalism including analyses of the ...


Supplement: The Rate Of Binary Black Hole Mergers Inferred From Advanced Ligo Observations Surrounding Gw150914, B. P. Abbott, K. Gill, B. Hughey, M. J. Szczepańczyk, M. Zanolin, Et Al. Dec 2016

Supplement: The Rate Of Binary Black Hole Mergers Inferred From Advanced Ligo Observations Surrounding Gw150914, B. P. Abbott, K. Gill, B. Hughey, M. J. Szczepańczyk, M. Zanolin, Et Al.

Publications

This article provides supplemental information for a Letter reporting the rate of (BBH) coalescences inferred from 16 days of coincident Advanced LIGO observations surrounding the transient (GW) signal GW150914. In that work we reported various rate estimates whose 90% confidence intervals fell in the range 2–600 Gpc−3 yr−1. Here we give details on our method and computations, including information about our search pipelines, a derivation of our likelihood function for the analysis, a description of the astrophysical search trigger distribution expected from merging BBHs, details on our computational methods, a description of the effects and our model ...


Results Of The Deepest All-Sky Survey For Continuous Gravitational Waves On Ligo S6 Data Running On The Einstein@Home Volunteer Distributed Computing Project, B. P. Abbott, K. Gill, B. Hughey, M. J. Szczepańczyk, Michele Zanolin, Et Al. Nov 2016

Results Of The Deepest All-Sky Survey For Continuous Gravitational Waves On Ligo S6 Data Running On The Einstein@Home Volunteer Distributed Computing Project, B. P. Abbott, K. Gill, B. Hughey, M. J. Szczepańczyk, Michele Zanolin, Et Al.

Publications

We report results of a deep all-sky search for periodic gravitational waves from isolated neutron stars in data from the S6 LIGO science run. The search was possible thanks to the computing power provided by the volunteers of the Einstein@Home distributed computing project.


Observation And Modeling Of Gravity Wave Propagation Through Reflection And Critical Layers Above Andes Lidar Observatory At Cerro Pachón, Chile, Bing Cao, Christopher J. Heale, Yafang Guo, Alan Z. Liu, Jonathan B. Snively Nov 2016

Observation And Modeling Of Gravity Wave Propagation Through Reflection And Critical Layers Above Andes Lidar Observatory At Cerro Pachón, Chile, Bing Cao, Christopher J. Heale, Yafang Guo, Alan Z. Liu, Jonathan B. Snively

Publications

A complex gravity wave event was observed from 04:30 to 08:10 UTC on 16 January 2015 by a narrow-band sodium lidar and an all-sky airglow imager located at Andes Lidar Observatory (ALO) in Cerro Pachón (30.25∘S, 70.73∘W), Chile. The gravity wave packet had a period of 18–35 min and a horizontal wavelength of about 40–50 km. Strong enhancements of the vertical wind perturbation, exceeding10 m s−1, were found at ∼90 km and ∼103 km, consistent with nearly evanescent wave behavior near a reflection layer. A reduction in vertical wavelength was found ...


Synchrony In A Boolean Network Of The L-Arabinose Operon In Escherichia Coli, Andy Jenkins, Matthew Macauley Nov 2016

Synchrony In A Boolean Network Of The L-Arabinose Operon In Escherichia Coli, Andy Jenkins, Matthew Macauley

Publications

The lactose operon in Escherichia coli was the first known gene regulatory network, and it is frequently used as a prototype for new modeling paradigms. Historically, many of these modeling frameworks use differential equations. More recently, Stigler and Veliz-Cuba proposed a Boolean network model that captures the bistability of the system and all of the biological steady states. In this paper, we model the well-known arabinose operon in E. coli with a Boolean network. This has several complex features not found in the lac operon, such as a protein that is both an activator and repressor, a DNA looping mechanism ...


Improved Analysis Of Gw150914 Using A Fully Spin-Precessing Waveform Model, B. P. Abbott, K. Gill, B. Hughey, M. J. Szczepańczyk, M. Zanolin, Et Al. Oct 2016

Improved Analysis Of Gw150914 Using A Fully Spin-Precessing Waveform Model, B. P. Abbott, K. Gill, B. Hughey, M. J. Szczepańczyk, M. Zanolin, Et Al.

Publications

This paper presents updated estimates of source parameters for GW150914, a binary black-hole coalescence event detected by the Laser Interferometer Gravitational-wave Observatory (LIGO) in 2015 [Abbott et al. Phys. Rev. Lett. 116, 061102 (2016).]. Abbott et al. [Phys. Rev. Lett. 116, 241102 (2016).] presented parameter estimation of the source using a 13-dimensional, phenomenological precessing-spin model (precessing IMRPhenom) and an 11-dimensional nonprecessing effective-one-body (EOB) model calibrated to numerical-relativity simulations, which forces spin alignment (nonprecessing EOBNR). Here, we present new results that include a 15-dimensional precessing-spin waveform model (precessing EOBNR) developed within the EOB formalism. (See article for remainder of abstract.)


Magnetic Reconnection With A Fast Perpendicular Sheared Flow, Xuanye Ma, Antonius Otto, Peter A. Delamere Oct 2016

Magnetic Reconnection With A Fast Perpendicular Sheared Flow, Xuanye Ma, Antonius Otto, Peter A. Delamere

Publications

Magnetic reconnection at the Earth's low‐latitude magnetopause near the flank region is likely associated with a large sheared flow, being frequently quasi‐perpendicular to the antiparallel magnetic field components. The magnitude of a fast sheared flow can be super‐Alfvénic and even overcome the local fast mode speed. A scaling analysis implies a contradiction between the Walén relation and the balance of the total pressure for magnetic reconnection with a supercritical perpendicular sheared flow. This study uses one‐ and two‐dimensional magnetohydrodynamic (MHD) simulations to demonstrate that the traditional reconnection layer violates the Walén relation but still maintains ...


Measuring The Impact Of Pollution Closures On Commercial Shellfish Harvest: The Case Of Soft-Shell Clams In Machias Bay, Maine, Keith S. Evans, Kevin Athearn, Xuan Chen, Kathleen P. Bell, Tora Johnson Oct 2016

Measuring The Impact Of Pollution Closures On Commercial Shellfish Harvest: The Case Of Soft-Shell Clams In Machias Bay, Maine, Keith S. Evans, Kevin Athearn, Xuan Chen, Kathleen P. Bell, Tora Johnson

Publications

Temporary closures of polluted coastal waters to shellfish harvesting protect human health but also generate broad socioeconomic impacts on rural, fishing-dependent communities. Improved understanding of these impacts could help coastal managers prioritize investments to protect water quality and mitigate the effects of coastal pollution. Using a regression model of monthly landings, we explore the impact of temporary closures on the commercial harvest of soft-shell clams (Mya arenaria) in the Machias Bay region of Maine (USA). We find that economic losses are significant and depend heavily on tidal activity, and the size, frequency and timing of closures. Over the nine-year sample ...


Book Review: The International Atlas Of Mars Exploration: From Spirit To Curiosity: V.2: 2004 To 2014, T. D. Oswalt Oct 2016

Book Review: The International Atlas Of Mars Exploration: From Spirit To Curiosity: V.2: 2004 To 2014, T. D. Oswalt

Publications

This document is Dr. Oswalt’s review of The International Atlas of Mars Exploration: from Spirit to Curiosity : V.2: 2004 to 2014 by Philip J. Stooke. 444p bibl index, 9781107030930 $145.00, 9781139344470 LC Call Number: 1000


The Wrecks Of Lake Champlain, Gary C. Kessler Oct 2016

The Wrecks Of Lake Champlain, Gary C. Kessler

Publications

Despite the dozens of historically significant wrecks in the lake, only nine are open for diving as part of the Lake Champlain Underwater Historic Preserve. For visitors to the area, five of the wrecks are easily accessible from Burlington, with four being in the immediate vicinity of Burlington Bay. This article will focus on these five wrecks.


Dynamics Of Orographic Gravity Waves Observed In The Mesosphere Over Auckland Islands During The Deep Propagating Gravity Wave Experiment (Deepwave), Stephen D. Eckermann, Dave Broutman, Jun Ma, James D. Doyle, Pierre-Dominique Pautet, Michael J. Taylor, Katrina Bossert, Bifford P. Williams, David C. Fritts, Ronald B. Smith Sep 2016

Dynamics Of Orographic Gravity Waves Observed In The Mesosphere Over Auckland Islands During The Deep Propagating Gravity Wave Experiment (Deepwave), Stephen D. Eckermann, Dave Broutman, Jun Ma, James D. Doyle, Pierre-Dominique Pautet, Michael J. Taylor, Katrina Bossert, Bifford P. Williams, David C. Fritts, Ronald B. Smith

Publications

On 14 July 2014 during the Deep Propagating Gravity Wave Experiment (DEEPWAVE), aircraft remote sensing instruments detected large-amplitude gravity wave oscillations within mesospheric airglow and sodium layers at altitudes z ~ 78–83 km downstream of the Auckland Islands, located ~1000 km south of Christchurch, New Zealand. A high-altitude reanalysis and a three-dimensional Fourier gravity wave model are used to investigate the dynamics of this event. At 0700 UTC when the first observations were made, surface flow across the islands’ terrain generated linear three-dimensional wave fields that propagated rapidly to z ~ 78 km, where intense breaking occurred in a narrow layer ...


Anisotropic Cubic Curvature Couplings, Quentin G. Bailey Sep 2016

Anisotropic Cubic Curvature Couplings, Quentin G. Bailey

Publications

To complement recent work on tests of spacetime symmetry in gravity, cubic curvature couplings are studied using an effective field theory description of spacetime-symmetry breaking. The associated mass-dimension-eight coefficients for Lorentz violation studied do not result in any linearized gravity modifications and instead are revealed in the first nonlinear terms in an expansion of spacetime around a flat background. We consider effects on gravitational radiation through the energy loss of a binary system and we study two-body orbital perturbations using the post-Newtonian metric. Some effects depend on the internal structure of the source and test bodies, thereby breaking the weak ...


Directly Comparing Gw150914 With Numerical Solutions Of Einstein's Equations For Binary Black Hole Coalescence, B. P. Abbott, K. Gill, B. Hughey, M. J. Szczepańczyk, M. Zanolin, Et Al. Sep 2016

Directly Comparing Gw150914 With Numerical Solutions Of Einstein's Equations For Binary Black Hole Coalescence, B. P. Abbott, K. Gill, B. Hughey, M. J. Szczepańczyk, M. Zanolin, Et Al.

Publications

We compare GW150914 directly to simulations of coalescing binary black holes in full general relativity, including several performed specifically to reproduce this event. Our calculations go beyond existing semianalytic models, because for all simulations—including sources with two independent, precessing spins—we perform comparisons which account for all the spin-weighted quadrupolar modes, and separately which account for all the quadrupolar and octopolar modes. Consistent with the posterior distributions reported by Abbott et al. [Phys. Rev. Lett. 116, 241102 (2016)] (at the 90% credible level), we find the data are compatible with a wide range of nonprecessing and precessing simulations. Follow-up ...


Bayesian Analysis Of Two Stellar Populations In Galactic Globular Clusters – Iii. Analysis Of 30 Clusters, R. Wagner-Kaiser, D. C. Stenning, A Sarajedini, Ted Von Hippel, D. A. Van Dyk, E. Robinson, W. H. Jefferys Sep 2016

Bayesian Analysis Of Two Stellar Populations In Galactic Globular Clusters – Iii. Analysis Of 30 Clusters, R. Wagner-Kaiser, D. C. Stenning, A Sarajedini, Ted Von Hippel, D. A. Van Dyk, E. Robinson, W. H. Jefferys

Publications

We use Cycle 21 Hubble Space Telescope (HST) observations and HST archival ACS Treasury observations of 30 Galactic globular clusters to characterize two distinct stellar populations. A sophisticated Bayesian technique is employed to simultaneously sample the joint posterior distribution of age, distance, and extinction for each cluster, as well as unique helium values for two populations within each cluster and the relative proportion of those populations. We find the helium differences among the two populations in the clusters fall in the range of ∼0.04 to 0.11. Because adequate models varying in carbon, nitrogen, and oxygen are not presently ...


Noncrossing Partitions, Toggles, And Homomesies, David Einstein, Miriam Farber, Emily Gunawan, Michael Joseph, Matthew Macauley, James Propp, Simon Rubinstein-Salzedo Sep 2016

Noncrossing Partitions, Toggles, And Homomesies, David Einstein, Miriam Farber, Emily Gunawan, Michael Joseph, Matthew Macauley, James Propp, Simon Rubinstein-Salzedo

Publications

We introduce n(n−1)/2 natural involutions (“toggles”) on the set S of noncrossing partitions π of size n, along with certain composite operations obtained by composing these involutions. We show that for many operations T of this kind, a surprisingly large family of functions f on S (including the function that sends π to the number of blocks of π) exhibits the homomesy phenomenon: the average of f over the elements of a T -orbit is the same for all T -orbits. We can apply our method of proof more broadly to toggle operations back on the collection ...


Ermakov Equation And Camassa-Holm Waves, Haret C. Rosu, Stefan C. Mancas Sep 2016

Ermakov Equation And Camassa-Holm Waves, Haret C. Rosu, Stefan C. Mancas

Publications

From the works of authors of this article, it is known that the solution of the Ermakov equation is an important ingredient in the spectral problem of the Camassa-Holm equation. Here, we review this interesting issue and consider in addition more features of the Ermakov equation which have an impact on the behavior of the shallow water waves as described by the Camassa-Holm equation.


On Safety Assessment Of Novel Approach To Robust Uav Flight Control In Gusty Environments, Vladimir Golubev, Petr Kazarin, William Mackunis, Sherry Borener, Derek Hufty Sep 2016

On Safety Assessment Of Novel Approach To Robust Uav Flight Control In Gusty Environments, Vladimir Golubev, Petr Kazarin, William Mackunis, Sherry Borener, Derek Hufty

Publications

In a follow-up to our previous study, the current work examines the gust-induced “cone of uncertainty” in a small unmanned aerial vehicle’s (UAV) flight trajectory addressed in the context of safety assessments of UAV operations. Such analysis is a critical facet of the integration of unmanned aerial systems (UAS) into the National Airspace System (NAS), particularly in terminal airspace. The paper describes a predictive, robust feedback-loop flight control model that is applicable to various classes of UAVs and unsteady flight-path scenarios. The control design presented in this paper extends previous research results by demonstrating asymptotic (zero steady-state error) altitude ...


Book Review: How Do You Find An Exoplanet?, T. D. Oswalt Sep 2016

Book Review: How Do You Find An Exoplanet?, T. D. Oswalt

Publications

This document is Dr. Oswalt’s review of How Do You Find an Exoplanet? by John Asher Johnson. Princeton, 2016 178p bibl index afp, 9780691156811 $35.00, 9781400873999


Systems Modeling To Improve The Hydro-Ecological Performance Of Diked Wetlands, Omar Alminagorta, David E. Rosenberg, Karin M. Kettenring Sep 2016

Systems Modeling To Improve The Hydro-Ecological Performance Of Diked Wetlands, Omar Alminagorta, David E. Rosenberg, Karin M. Kettenring

Publications

Water scarcity and invasive vegetation threaten arid-region wetlands and wetland managers seek ways to enhance wetland ecosystem services with limited water, labor, and financial resources. While prior systems modeling efforts have focused on water management to improve flow-based ecosystem and habitat objectives, here we consider water allocation and invasive vegetation management that jointly target the concurrent hydrologic and vegetation habitat needs of priority wetland bird species. We formulate a composite weighted usable area for wetlands (WU) objective function that represents the wetland surface area that provides suitable water level and vegetation cover conditions for priority bird species. Maximizing the WU ...


New Halo White Dwarf Candidates In The Sloan Digital Sky Survey, Kyra Dame, A. Gianninas, Mukremin Kilic, Jeffrey A. Munn, Warren R. Brown, Kurtis A. Williams, Ted Von Hippel, Hugh C. Harris Aug 2016

New Halo White Dwarf Candidates In The Sloan Digital Sky Survey, Kyra Dame, A. Gianninas, Mukremin Kilic, Jeffrey A. Munn, Warren R. Brown, Kurtis A. Williams, Ted Von Hippel, Hugh C. Harris

Publications

We present optical spectroscopy and near-infrared photometry of 57 faint (g = 19–22) high proper motion white dwarfs identified through repeat imaging of ≈3100 deg2 of the Sloan Digital Sky Survey footprint by Munn et al. We use ugriz and JHphotometry to perform a model atmosphere analysis, and identify 10 ultracool white dwarfs with Teff < 4000 K, including the coolest pure H atmosphere white dwarf currently known, J1657+2638, with Teff = 3550 ± 100 K. The majority of the objects with cooling ages larger than 9 Gyr display thick disc kinematics and constrain the age of the thick disc to ≥11 Gyr. There are four white dwarfs in our sample with large tangential ...


Combined Search For Lorentz Violation In Short-Range Gravity, Cheng-Gang Shao, Yu-Jie Tan, Wen-Hai Tan, Shan-Qing Yang, Jun Luo, Michael Edmund Tobar, Quentin G. Bailey, Et Al. Aug 2016

Combined Search For Lorentz Violation In Short-Range Gravity, Cheng-Gang Shao, Yu-Jie Tan, Wen-Hai Tan, Shan-Qing Yang, Jun Luo, Michael Edmund Tobar, Quentin G. Bailey, Et Al.

Publications

Short-range experiments testing the gravitational inverse-square law at the submillimeter scale offer uniquely sensitive probes of Lorentz invariance. (See article for remainder of abstract.)


Leveraging The Power Of Place In Citizen Science For Effective Conservation Decision Making, Gregory Newman, M. Chandler, M. Clyde, B. Mcgreavy, M. Haklay, H. Ballard, S. Gray, R. Scarpino, D. Mellor, J. Gallo Aug 2016

Leveraging The Power Of Place In Citizen Science For Effective Conservation Decision Making, Gregory Newman, M. Chandler, M. Clyde, B. Mcgreavy, M. Haklay, H. Ballard, S. Gray, R. Scarpino, D. Mellor, J. Gallo

Publications

Many citizen science projects are place-based - built on in-person participation and motivated by local conservation. When done thoughtfully, this approach to citizen science can transform humans and their environment. Despite such possibilities, many projects struggle to meet decision-maker needs, generate useful data to inform decisions, and improve social-ecological resilience. Here, we define leveraging the ‘power of place’ in citizen science, and posit that doing this improves conservation decision making, increases participation, and improves community resilience. First, we explore ‘place’ and identify five place dimensions: social-ecological, narrative and name-based, knowledge-based, emotional and affective, and performative. We then thematically analyze 134 case ...


Cytoplasmic Dynein Binding, Run Length, And Velocity Are Guided By Long-Range Electrostatic Interactions, Lin Li, Joshua Alper, Emil Alexov Aug 2016

Cytoplasmic Dynein Binding, Run Length, And Velocity Are Guided By Long-Range Electrostatic Interactions, Lin Li, Joshua Alper, Emil Alexov

Publications

Dyneins are important molecular motors involved in many essential biological processes, including cargo transport along microtubules, mitosis, and in cilia. Dynein motility involves the coupling of microtubule binding and unbinding to a change in the configuration of the linker domain induced by ATP hydrolysis, which occur some 25 nm apart. This leaves the accuracy of dynein stepping relatively inaccurate and susceptible to thermal noise. Using multi-scale modeling with a computational focusing technique, we demonstrate that the microtubule forms an electrostatic funnel that guides the dynein’s microtubule binding domain (MTBD) as it finally docks to the precise, keyed binding location ...


Current Sheet Flapping Motions In The Tailwind Flow Of Magnetic Reconnection, Mingyu Wu, Quanming Lu, Martin Volwerk, Zoltán Vörös, Xuanye Ma, Shui Wang Aug 2016

Current Sheet Flapping Motions In The Tailwind Flow Of Magnetic Reconnection, Mingyu Wu, Quanming Lu, Martin Volwerk, Zoltán Vörös, Xuanye Ma, Shui Wang

Publications

The feature and origin of current sheet flapping motions are one of most interesting issues of magnetospheric dynamics. In this paper we report the flapping motion of the current sheet detected in the tailward flow of a magnetic reconnection event on 7 February 2009. This flapping motion with frequency about 12 mHz was accompanied by magnetic turbulence. The observations by the tail‐elongated fleet of five Time History of Events and Macroscale Interactions during Substorms probes indicate that these flapping oscillations were rather confined within the tailward flow than were due to a global process. This flapping motion could be ...


Completeness Of The Nearby White Dwarf Sample: Let Us Count The Ways, Terry D. Oswalt, Jay Holberg, Edward M. Sion Jul 2016

Completeness Of The Nearby White Dwarf Sample: Let Us Count The Ways, Terry D. Oswalt, Jay Holberg, Edward M. Sion

Publications

We have recently extended our ongoing survey of the local white dwarf population, effectively doubling the sample volume. Based upon the latest distance determinations, Holberg et al. (2016) estimated the present 20 pc and 25 pc samples were about 86 and 68 percent complete, respectively. Here we examine how the completeness of the 25 pc sample depends upon other observables such as apparent magnitude, proper motion, photometric color index, etc. The results may provide additional clues to why “Sirius-Like systems” are underrepresented in the extended 25 pc sample and how additional nearby single white dwarf stars may be found.


Planning For Sustainability In Small Municipalities: The Influence Of Interest Groups, Growth Patterns, And Institutional Characteristics, Vanessa R. Levesque, Kathleen P. Bell, Aram J K Calhoun Jul 2016

Planning For Sustainability In Small Municipalities: The Influence Of Interest Groups, Growth Patterns, And Institutional Characteristics, Vanessa R. Levesque, Kathleen P. Bell, Aram J K Calhoun

Publications

How and why small municipalities promote sustainability through planning efforts is poorly understood. We analyzed ordinances in 451 Maine municipalities and tested theories of policy adoption using regression analysis.We found that smaller communities do adopt programs that contribute to sustainability relevant to their scale and context. In line with the political market theory, we found that municipalities with strong environmental interests, higher growth, and more formal governments were more likely to adopt these policies. Consideration of context and capacity in planning for sustainability will help planners better identify and benefit from collaboration, training, and outreach opportunities.