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2015

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Articles 2371 - 2400 of 12617

Full-Text Articles in Physical Sciences and Mathematics

An Adaptive Level Set Approach For Modeling Damage Due To Galvanic Corrosion, Joseph Wilder, Curtis Clemons, Dmitry Golovaty, Kevin Kreider, Gerald Young, R. Lillard Sep 2015

An Adaptive Level Set Approach For Modeling Damage Due To Galvanic Corrosion, Joseph Wilder, Curtis Clemons, Dmitry Golovaty, Kevin Kreider, Gerald Young, R. Lillard

Gerald W Young

This article presents an approach to solving problems related to galvanic corrosion that involve moving boundaries (due to preferential corrosion of one of the metals in the system). The method incorporates an adaptive (node based, finite difference) grid technique for the treatment of boundary-related singularities that arise in the calculation of the electric potential. Simulation of the time evolution of the damage done by the corroding interface is performed using of a level set formulation. An analysis of the convergence of the method and a comparison with experimental data from the literature are included.

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Fixed Point Theory For Non-Self Maps, Linda Saliga Sep 2015

Fixed Point Theory For Non-Self Maps, Linda Saliga

Linda Saliga

No abstract provided.

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Global Magnetic Confinement For The 1.5d Vlasov-Maxwell System, Toan Nguyen, Truyen Nguyen, Walter Strauss Sep 2015

Global Magnetic Confinement For The 1.5d Vlasov-Maxwell System, Toan Nguyen, Truyen Nguyen, Walter Strauss

Truyen V. Nguyen

We establish the global-in-time existence and uniqueness of classical solutions to the ``one and one-half'' dimensional relativistic Vlasov--Maxwell systems in a bounded interval, subject to an external magnetic field which is infinitely large at the spatial boundary. We prove that the large external magnetic field confines the particles to a compact set away from the boundary. This excludes the known singularities that typically occur due to particles that repeatedly bounce off the boundary. In addition to the confinement, we follow the techniques introduced by Glassey and Schaeffer, who studied the Cauchy problem without boundaries.

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One-Dimensional Pressureless Gas Systems With/Without Viscosity, Truyen Nguyen, Adrian Tudorascu Sep 2015

One-Dimensional Pressureless Gas Systems With/Without Viscosity, Truyen Nguyen, Adrian Tudorascu

Truyen V. Nguyen

A general global existence result for one-dimensional pressureless Euler/Euler-Poisson systems with or without viscosity is obtained by employing the “sticky particles” model. We first construct entropy solutions for some appropriate scalar conservation laws, then we show that these solutions encode all the information necessary to obtain solutions for the pressureless systems. Another novel contribution is the stability and uniqueness of solutions, which is obtained via a contraction principle in the Wasserstein metric.

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Critical Assessment Of Outcomes In Acute Aortic Dissection (Type A) At A Community Hospital: A 10 Year Review, Tim S. Misselbeck Md, James K. Wu Md, Stephen Deturk Ba, Michael F. Szwerc Md, Sanjay M. Mehta Md, Theodore G. Phillips Md, Gary W. Szydlowski Md, Raymond L. Singer Md Sep 2015

Critical Assessment Of Outcomes In Acute Aortic Dissection (Type A) At A Community Hospital: A 10 Year Review, Tim S. Misselbeck Md, James K. Wu Md, Stephen Deturk Ba, Michael F. Szwerc Md, Sanjay M. Mehta Md, Theodore G. Phillips Md, Gary W. Szydlowski Md, Raymond L. Singer Md

Raymond L Singer MD

No abstract provided.

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Conventional Isolated Aortic Valve Replacement In Octogenarians: A 10-Year Single Center Experience, James K. Wu Md, Justin D. Roberts Do, Gregory S. Troutman Bs, Michael J. Weiss Mph, Sanjay M. Mehta Md, Theodore G. Phillips Md, Michael F. Szwerc Md, Gary W. Szydlowski Md, Tim S. Misselbeck Md, Raymond L. Singer Md Sep 2015

Conventional Isolated Aortic Valve Replacement In Octogenarians: A 10-Year Single Center Experience, James K. Wu Md, Justin D. Roberts Do, Gregory S. Troutman Bs, Michael J. Weiss Mph, Sanjay M. Mehta Md, Theodore G. Phillips Md, Michael F. Szwerc Md, Gary W. Szydlowski Md, Tim S. Misselbeck Md, Raymond L. Singer Md

Raymond L Singer MD

No abstract provided.

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Putting The West Antarctic Ice Sheet Into Context, George H. Denton, Brenda L. Hall Sep 2015

Putting The West Antarctic Ice Sheet Into Context, George H. Denton, Brenda L. Hall

University of Maine Office of Research Administration: Grant Reports

This award supports a project to develop new insights into the cause and pattern of events during the last glacial termination in South America and Antarctica. One emerging view is that a warming Southern Ocean (SO), driven by a chain of events initiated in the Northern Hemisphere (NH) and tied to the interhemispheric climate seesaw of the last termination, was the underlying mechanism that drove the West Antarctic ice sheet (WAIS) from its Late Glacial Maximum (LGM) position back to present-day grounding lines. This ocean thermal forcing would have impacted WAIS by accelerating basal melt rates on fringing floating ice …

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Far From 'Easy' Spectroscopy With The 8Π And Griffin Spectrometers At Triumf-Isac, Steven W. Yates, P. E. Garrett, A. J. Radich, J. M. Allmond, C. Andreoiu, G. C. Ball, P. C. Bender, L. Bianco, V. Bildstein, H. Bidaman, R. Braid Sep 2015

Far From 'Easy' Spectroscopy With The 8Π And Griffin Spectrometers At Triumf-Isac, Steven W. Yates, P. E. Garrett, A. J. Radich, J. M. Allmond, C. Andreoiu, G. C. Ball, P. C. Bender, L. Bianco, V. Bildstein, H. Bidaman, R. Braid

Chemistry Faculty Publications

The 8π spectrometer, installed at the TRIUMF-ISAC facility, was the world's most sensitive γ-ray spectrometer dedicated to β-decay studies. A description is given of the 8π spectrometer and its auxiliary detectors including the plastic scintillator array SCEPTAR used for β-particle tagging and the Si(Li) array PACES for conversion electron measurements, its moving tape collector, and its data acquisition system. The recent investigation of the decay of 124Cs to study the nuclear structure of 124Xe, and how the β-decay measurements complemented previous Coulomb excitation studies, is highlighted, including the extraction of the deformation parameters for the excited 0+ …

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On Varieties Of Doubly Robust Estimators Under Missing Not At Random With An Ancillary Variable, Wang Miao, Eric Tchetgen Tchetgen Sep 2015

On Varieties Of Doubly Robust Estimators Under Missing Not At Random With An Ancillary Variable, Wang Miao, Eric Tchetgen Tchetgen

Harvard University Biostatistics Working Paper Series

No abstract provided.

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Magnetization Dynamics Of Imprinted Non-Collinear Spin Textures, Robert Streubel, Peter Fischer, Martin Kopte, Oliver G. Schmidt, Denys Makarov Sep 2015

Magnetization Dynamics Of Imprinted Non-Collinear Spin Textures, Robert Streubel, Peter Fischer, Martin Kopte, Oliver G. Schmidt, Denys Makarov

Robert Streubel Papers

We study the magnetization dynamics of non-collinear spin textures realized via imprint of the magnetic vortex state in soft permalloy into magnetically hard out-of-plane magnetized Co/Pd nanopatterned heterostructures. Tuning the interlayer exchange coupling between soft- and hard-magnetic subsystems provides means to tailor the magnetic state in the Co/Pd stack from being vortex- to donut-like with different core sizes. While the imprinted vortex spin texture leads to the dynamics similar to the one observed for vortices in permalloy disks, the donut-like state causes the appearance of two gyrofrequencies characteristic of the early and later stages of the magnetization dynamics. The dynamics …

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2d (0,2) Quiver Gauge Theories And D-Branes, Sebastian Franco, Dongwook Ghim, Sangmin Lee, Rak-Kyeong Seong, Daisuke Yokoyama Sep 2015

2d (0,2) Quiver Gauge Theories And D-Branes, Sebastian Franco, Dongwook Ghim, Sangmin Lee, Rak-Kyeong Seong, Daisuke Yokoyama

Publications and Research

We initiate a systematic study of 2d(0,2) quiver gauge theories on the world-volume of D1-branes probing singular toric Calabi-Yau 4-folds. We present an algorithm for efficiently calculating the classical mesonic moduli spaces of these theories, which cor-respond to the probed geometries. We also introduce a systematic procedure for constructing the gauge theories for arbitrary toric singularities by means of partial resolution, which translates to higgsing in the field theory. Finally, we introduce Brane Brick Models, a novel class of brane configurations that consist of D4-branes suspended from an NS5-brane wrap-ping a holomorphic surface, tessellating a 3-torus. Brane Brick Models are …

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Liquid Crystal Janus Emulsion Droplets: Preparation, Tumbling, And Swimming, J. Jeong, A. Gross, W.-S. Wei, F. Tu, D. Lee, Peter J. Collings, A. G. Yodh Sep 2015

Liquid Crystal Janus Emulsion Droplets: Preparation, Tumbling, And Swimming, J. Jeong, A. Gross, W.-S. Wei, F. Tu, D. Lee, Peter J. Collings, A. G. Yodh

Physics & Astronomy Faculty Works

This study introduces liquid crystal (LC) Janus droplets. We describe a process for the preparation of these droplets, which consist of nematic LC and polymer compartments. The process employs solvent-induced phase separation in emulsion droplets generated by microfluidics. The droplet morphology was systematically investigated and demonstrated to be sensitive to the surfactant concentration in the background phase, the compartment volume ratio, and the possible coalescence of multiple Janus droplets. Interestingly, the combination of a polymer and an anisotropic LC introduces new functionalities into Janus droplets, and these properties lead to unusual dynamical behaviors. The different densities and solubilities of the …

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The Noncommutative Geometry Of K-Graph C*-Algebras, David A. Pask, Adam Rennie, Aidan Sims Sep 2015

The Noncommutative Geometry Of K-Graph C*-Algebras, David A. Pask, Adam Rennie, Aidan Sims

Associate Professor Adam Rennie

This paper is comprised of two related parts. First we discuss which k-graph algebras have faithful gauge invariant traces, where the gauge action of T^k is the canonical one. We give a sufficient condition for the existence of such a trace, identify the C*-algebras of k-graphs satisfying this condition up to Morita equivalence, and compute their K-theory. For k-graphs with faithful gauge invariant trace, we construct a smooth (k,infinity)-summable semifinite spectral triple. We use the semifinite local index theorem to compute the pairing with K-theory. This numerical pairing can be obtained by applying the trace to a KK-pairing with values …

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A Pairwise Likelihood Augmented Estimator For The Cox Model Under Left-Truncation, Fan Wu, Sehee Kim, Jing Qin, Rajiv Saran, Yi Li Sep 2015

A Pairwise Likelihood Augmented Estimator For The Cox Model Under Left-Truncation, Fan Wu, Sehee Kim, Jing Qin, Rajiv Saran, Yi Li

The University of Michigan Department of Biostatistics Working Paper Series

Survival data collected from prevalent cohorts are subject to left-truncation and the analysis is challenging. Conditional approaches for left-truncated data under the Cox model are inefficient as they typically ignore the information in the marginal likelihood of the truncation times. Length-biased sampling methods can improve the estimation efficiency but only when the stationarity assumption of the disease incidence holds, i.e., the truncation distribution is uniform; otherwise they may generate biased estimates. In this paper, we propose a semi-parametric method for the Cox model under general left-truncation, where the truncation distribution is unspecified. Our approach is to make inference based on …

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Diurnal And Seasonal Variations Of No, No2 And Pm2.5 Mass As A Function Of Traffic Volumes Alongside An Urban Arterial, Christine M. Kendrick, Peter Koonce, Linda A. George Sep 2015

Diurnal And Seasonal Variations Of No, No2 And Pm2.5 Mass As A Function Of Traffic Volumes Alongside An Urban Arterial, Christine M. Kendrick, Peter Koonce, Linda A. George

Environmental Science and Management Faculty Publications and Presentations

Urban arterial corridors are landscapes that give rise to short and long-term exposures to transportation-related pollution. With high traffic volumes and a wide mix of road users, urban arterial environments are important targets for improved exposure assessment to traffic-related pollution. A common method to estimate exposure is to use traffic volumes as a proxy. The study presented here analyzes a unique yearlong dataset of simultaneous roadside air quality and traffic observations for a U.S. arterial to assess the reliability of using traffic volumes as a proxy for traffic-related exposure. Results show how the relationships of traffic volumes with NO and …

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One-Dimensional Approach To Modeling Damage Evolution In Galvanic Corrosion, Aaron Stenta, S. Basco, A. Smith, Curtis Clemons, Dimitry Golovaty, Kevin Kreider, Joseph Wilder, Gerald Young, Robert Lillard Sep 2015

One-Dimensional Approach To Modeling Damage Evolution In Galvanic Corrosion, Aaron Stenta, S. Basco, A. Smith, Curtis Clemons, Dimitry Golovaty, Kevin Kreider, Joseph Wilder, Gerald Young, Robert Lillard

Kevin L. Kreider

A one-dimensional mathematical model is developed to describe time-dependent damage evolution in well-mixed (spatially uniform species concentrations) galvanic systems using an IR drop approach. An asymptotic procedure taking advantage of disparity in length scales (thin film approximation for the electrolyte thickness) is used to derive the model. Limitations that result from the reduction of dimension are described, along with an analysis demonstrating the ability of the 1D model to capture physical phenomena, such as area ratio effects. Computed potential, current density, and corrosion damage profiles are compared and verified with experimental data available in the literature and 2D galvanic corrosion …

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An Adaptive Level Set Approach For Modeling Damage Due To Galvanic Corrosion, Joseph Wilder, Curtis Clemons, Dmitry Golovaty, Kevin Kreider, Gerald Young, R. Lillard Sep 2015

An Adaptive Level Set Approach For Modeling Damage Due To Galvanic Corrosion, Joseph Wilder, Curtis Clemons, Dmitry Golovaty, Kevin Kreider, Gerald Young, R. Lillard

Kevin L. Kreider

This article presents an approach to solving problems related to galvanic corrosion that involve moving boundaries (due to preferential corrosion of one of the metals in the system). The method incorporates an adaptive (node based, finite difference) grid technique for the treatment of boundary-related singularities that arise in the calculation of the electric potential. Simulation of the time evolution of the damage done by the corroding interface is performed using of a level set formulation. An analysis of the convergence of the method and a comparison with experimental data from the literature are included.

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Localized Corrosion Risk Assessment Using Markov Analysis, K Mccallum, J Zhao, M Workman, M Iannuzzi, M Kappes, Joe Payer, Curtis Clemons, S Chawla, Kevin Kreider, Nao Mimoto, Gerald Young Sep 2015

Localized Corrosion Risk Assessment Using Markov Analysis, K Mccallum, J Zhao, M Workman, M Iannuzzi, M Kappes, Joe Payer, Curtis Clemons, S Chawla, Kevin Kreider, Nao Mimoto, Gerald Young

Kevin L. Kreider

The objective of this work was to develop the foundation for an interactive corrosion risk management tool for assessing the probability of failure of equipment/infrastructure as a function of threats (such as pitting corrosion and coating degradation) and mitigation schemes (such as inhibitors and coatings). The application of this work was to assist with corrosion management and maintenance planning of equipment/infrastructure given dynamic changes in environmental conditions. Markov models are developed to estimate pitting damage accumulation density distributions as a function of input parameters for pit nucleation and growth rates. The input parameters are selected based upon characterization with experimental …

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One-Dimensional Approach To Modeling Damage Evolution In Galvanic Corrosion, Aaron Stenta, S. Basco, A. Smith, Curtis Clemons, Dimitry Golovaty, Kevin Kreider, Joseph Wilder, Gerald Young, Robert Lillard Sep 2015

One-Dimensional Approach To Modeling Damage Evolution In Galvanic Corrosion, Aaron Stenta, S. Basco, A. Smith, Curtis Clemons, Dimitry Golovaty, Kevin Kreider, Joseph Wilder, Gerald Young, Robert Lillard

Dimitry Golovaty

A one-dimensional mathematical model is developed to describe time-dependent damage evolution in well-mixed (spatially uniform species concentrations) galvanic systems using an IR drop approach. An asymptotic procedure taking advantage of disparity in length scales (thin film approximation for the electrolyte thickness) is used to derive the model. Limitations that result from the reduction of dimension are described, along with an analysis demonstrating the ability of the 1D model to capture physical phenomena, such as area ratio effects. Computed potential, current density, and corrosion damage profiles are compared and verified with experimental data available in the literature and 2D galvanic corrosion …

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On A Conjecture Of Gluck, James Cossey, Zoltan Halasi, Attila Maroti, Hung Nuguyen Sep 2015

On A Conjecture Of Gluck, James Cossey, Zoltan Halasi, Attila Maroti, Hung Nuguyen

James P. Cossey

Let F(G) and b(G) respectively denote the Fitting subgroup and the largest degree of an irreducible complex character of a finite group G. A well-known conjecture of D. Gluck claims that if G is solvable then |G:F(G)|≤b(G)2. We confirm this conjecture in the case where |F(G)| is coprime to 6. We also extend the problem to arbitrary finite groups and prove several results showing that the largest irreducible character degree of a finite group strongly controls the group structure.

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One-Dimensional Approach To Modeling Damage Evolution In Galvanic Corrosion, Aaron Stenta, S. Basco, A. Smith, Curtis Clemons, Dimitry Golovaty, Kevin Kreider, Joseph Wilder, Gerald Young, Robert Lillard Sep 2015

One-Dimensional Approach To Modeling Damage Evolution In Galvanic Corrosion, Aaron Stenta, S. Basco, A. Smith, Curtis Clemons, Dimitry Golovaty, Kevin Kreider, Joseph Wilder, Gerald Young, Robert Lillard

Curtis B. Clemons

A one-dimensional mathematical model is developed to describe time-dependent damage evolution in well-mixed (spatially uniform species concentrations) galvanic systems using an IR drop approach. An asymptotic procedure taking advantage of disparity in length scales (thin film approximation for the electrolyte thickness) is used to derive the model. Limitations that result from the reduction of dimension are described, along with an analysis demonstrating the ability of the 1D model to capture physical phenomena, such as area ratio effects. Computed potential, current density, and corrosion damage profiles are compared and verified with experimental data available in the literature and 2D galvanic corrosion …

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An Adaptive Level Set Approach For Modeling Damage Due To Galvanic Corrosion, Joseph Wilder, Curtis Clemons, Dmitry Golovaty, Kevin Kreider, Gerald Young, R. Lillard Sep 2015

An Adaptive Level Set Approach For Modeling Damage Due To Galvanic Corrosion, Joseph Wilder, Curtis Clemons, Dmitry Golovaty, Kevin Kreider, Gerald Young, R. Lillard

Curtis B. Clemons

This article presents an approach to solving problems related to galvanic corrosion that involve moving boundaries (due to preferential corrosion of one of the metals in the system). The method incorporates an adaptive (node based, finite difference) grid technique for the treatment of boundary-related singularities that arise in the calculation of the electric potential. Simulation of the time evolution of the damage done by the corroding interface is performed using of a level set formulation. An analysis of the convergence of the method and a comparison with experimental data from the literature are included.

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Localized Corrosion Risk Assessment Using Markov Analysis, K Mccallum, J Zhao, M Workman, M Iannuzzi, M Kappes, Joe Payer, Curtis Clemons, S Chawla, Kevin Kreider, Nao Mimoto, Gerald Young Sep 2015

Localized Corrosion Risk Assessment Using Markov Analysis, K Mccallum, J Zhao, M Workman, M Iannuzzi, M Kappes, Joe Payer, Curtis Clemons, S Chawla, Kevin Kreider, Nao Mimoto, Gerald Young

Curtis B. Clemons

The objective of this work was to develop the foundation for an interactive corrosion risk management tool for assessing the probability of failure of equipment/infrastructure as a function of threats (such as pitting corrosion and coating degradation) and mitigation schemes (such as inhibitors and coatings). The application of this work was to assist with corrosion management and maintenance planning of equipment/infrastructure given dynamic changes in environmental conditions. Markov models are developed to estimate pitting damage accumulation density distributions as a function of input parameters for pit nucleation and growth rates. The input parameters are selected based upon characterization with experimental …

Go to article

Localized Corrosion Risk Assessment Using Markov Analysis, K Mccallum, J Zhao, M Workman, M Iannuzzi, M Kappes, Joe Payer, Curtis Clemons, S Chawla, Kevin Kreider, Nao Mimoto, Gerald Young Sep 2015

Localized Corrosion Risk Assessment Using Markov Analysis, K Mccallum, J Zhao, M Workman, M Iannuzzi, M Kappes, Joe Payer, Curtis Clemons, S Chawla, Kevin Kreider, Nao Mimoto, Gerald Young

Nao Mimoto

The objective of this work was to develop the foundation for an interactive corrosion risk management tool for assessing the probability of failure of equipment/infrastructure as a function of threats (such as pitting corrosion and coating degradation) and mitigation schemes (such as inhibitors and coatings). The application of this work was to assist with corrosion management and maintenance planning of equipment/infrastructure given dynamic changes in environmental conditions. Markov models are developed to estimate pitting damage accumulation density distributions as a function of input parameters for pit nucleation and growth rates. The input parameters are selected based upon characterization with experimental …

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Alterations In Gene Array Patterns In Dendritic Cells From Aged Humans, Jia-Ning Cao, Anshu Agrawal, Edward Sharman, Zhenyu Jia, Sudhir Gupta Sep 2015

Alterations In Gene Array Patterns In Dendritic Cells From Aged Humans, Jia-Ning Cao, Anshu Agrawal, Edward Sharman, Zhenyu Jia, Sudhir Gupta

Zhenyu Jia

Dendritic cells (DCs) are major antigen-presenting cells that play a key role in initiating and regulating innate and adaptive immune responses. DCs are critical mediators of tolerance and immunity. The functional properties of DCs decline with age. The purpose of this study was to define the age-associated molecular changes in DCs by gene array analysis using Affymatrix GeneChips. The expression levels of a total of 260 genes (1.8%) were significantly different (144 down-regulated and 116 upregulated) in monocyte-derived DCs (MoDCs) from aged compared to young human donors. Of the 260 differentially expressed genes, 24% were down-regulated by more than 3-fold, …

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Topical Rapamycin Systematically Suppresses The Early Stages Of Pulsed Dye Laser-Induced Angiogenesis Pathways, Lin Gao, Sydney Phan, Dawnica Nadora, Margarita Chernova, Victor Sun, Salena Preciado, Brittany Ballew, Zhenyu Jia, Wangcun Jia, Gang Wang, Martin Mihm, J. Nelson, Wenbin Tan Sep 2015

Topical Rapamycin Systematically Suppresses The Early Stages Of Pulsed Dye Laser-Induced Angiogenesis Pathways, Lin Gao, Sydney Phan, Dawnica Nadora, Margarita Chernova, Victor Sun, Salena Preciado, Brittany Ballew, Zhenyu Jia, Wangcun Jia, Gang Wang, Martin Mihm, J. Nelson, Wenbin Tan

Zhenyu Jia

BACKGROUND: Administration of topical rapamycin (RPM) suppresses the regeneration and revascularization of photocoagulated blood vessels induced by pulsed dye laser (PDL). OBJECTIVE: To systematically elucidate the molecular pathophysiology of the inhibition of PDL-induced angiogenesis by topical RPM in a rodent model. METHODS: The mRNA expression profiles of 86 angiogenic genes and phosphorylation levels of ribosomal protein S6 kinase (P70S6K) in rodent skin were examined with or without topical RPM administration post-PDL exposure. RESULTS: The PDL-induced systematic increases in transcriptional levels of angiogenic genes showed a peak expression at days 3-7 post-PDL in rodent skin. Topical application of 1% RPM significantly …

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Transcultural Self-Efficacy Perceptions Of Baccalaureate Nursing Students, Margaret Halter, Faye Grund, Mark Fridline, Sharon See, Lisa Young, Carol Reece Sep 2015

Transcultural Self-Efficacy Perceptions Of Baccalaureate Nursing Students, Margaret Halter, Faye Grund, Mark Fridline, Sharon See, Lisa Young, Carol Reece

Mark Fridline PhD

Addressing the health care needs of a 21st-century nation that is experiencing increased diversity and disparity will require new models of educating future providers. The cultural competence and confidence model was the guiding framework in a study evaluating the influence of cultural educational offerings on the transcultural self-efficacy (TSE) perceptions in baccalaureate nursing students. The Transcultural Self-Efficacy Tool was used to measure perceived TSE in a pretest (N = 260), posttest (N = 236) study over an academic year. Significant changes were demonstrated in overall self-efficacy and on the cognitive, practical, and affective subscales. A classification and regression …

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Observations And Interpretation Of Gravity Wave Induced Fluctuations In The O I (557.7 Nm) Airglow, G. Schubert, R. L. Walterscheid, Michael P. Hickey Ph.D., C. A. Tepley Sep 2015

Observations And Interpretation Of Gravity Wave Induced Fluctuations In The O I (557.7 Nm) Airglow, G. Schubert, R. L. Walterscheid, Michael P. Hickey Ph.D., C. A. Tepley

Michael P. Hickey

Observations of fluctuations in the intensity and temperature of the O I (557.7 nm) airglow taken at Arecibo in 1989 are reported and interpreted on the assumption that they are caused by gravity waves propagating through the emission layer. The data give the magnitude of Krassovsky's ratio as 3.5 ± 2.2, at periods between about 5 and 10 hours. Comparison with theory shows that the gravity waves responsible for the measured airglow variations must have long wavelengths of several thousand kilometers. The observed phases of Krassovsky's ratio are in good agreement with theoretically predicted values at the long wavelengths and …

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Gravity Wave Propagation Directions Inferred From Satellite Observations Including Smearing Effects, Jason S. Brown, Michael P. Hickey Ph.D. Sep 2015

Gravity Wave Propagation Directions Inferred From Satellite Observations Including Smearing Effects, Jason S. Brown, Michael P. Hickey Ph.D.

Michael P. Hickey

We simulate space-based, sublimb viewing observations of airglow brightness fluctuations caused by atmospheric gravity wave interactions with the O2 atmospheric airglow, and we demonstrate that because of the geometry associated with such observations, the brightness fluctuations observed for the optically thick 0–0 band emission will always appear stronger for waves traveling toward the observer (the satellite). The effect should be most noticeable for waves having relatively small vertical wavelengths (∼10 km) and horizontal wavelengths of 50 km or greater. For waves of short (∼100 km) horizontal wavelength, the brightness fluctuation anisotropy with respect to viewing direction may also be evident …

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Further Investigations Of A Mesospheric Inversion Layer Observed In The Aloha-93 Campaign, Tai-Yin Huang, Michael P. Hickey Ph.D., Tai-Fu Tuan Sep 2015

Further Investigations Of A Mesospheric Inversion Layer Observed In The Aloha-93 Campaign, Tai-Yin Huang, Michael P. Hickey Ph.D., Tai-Fu Tuan

Michael P. Hickey

Temperature and wind data obtained from a Na wind/temperature lidar operated by the University of Illinois group during the Airborne Lidar and Observations of the Hawaiian Airglow (ALOHA-93) Campaign, previously analyzed by Huang et al. [1998] using an isothermal Brunt-Va¨isa¨la¨ frequency, have been reexamined to include temperature gradients in the calculation of the Richardson number. In the previous analysis using the isothermal Brunt-Va¨isa¨la¨ frequency the existence of convective instability could not be assessed. New analysis shows that the nonisothermal Richardson number preserves some features found previously, with some striking differences noticable at times between 0900 and 1030 UT. The nonisothermal …

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