Physical Sciences and Mathematics Commons^™

Symmetric Criticality In Classical Field Theory, Charles G. Torre

Charles G. Torre

This is a brief overview of work done by Ian Anderson, Mark Fels, and myself on symmetry reduction of Lagrangians and Euler-Lagrange equations, a subject closely related to Palais’ Principle of Symmetric Criticality. After providing a little history, I describe necessary and sufficient conditions on a group action such that reduction of a group-invariant Lagrangian by the symmetry group yields the correct symmetry-reduced Euler-Lagrange equations.

Symmetric Criticality In Classical Field Theory, Charles G. Torre

Charles G. Torre

This is a presentation made at the XIX Fall Workshop on Geometry and Physics, held at Porto, Portugal in September 2010. It is a brief overview of work done by Ian Anderson, Mark Fels, and myself on symmetry reduction of Lagrangians and Euler-Lagrange equations, a subject closely related to Palais’ Principle of Symmetric Criticality. After providing a little history, I describe necessary and sufficient conditions on a group action such that reduction of a group-invariant Lagrangian by the symmetry group yields the correct symmetry-reduced Euler-Lagrange equations

An Entrepreneurial Approach To Librarianship, Flora G. Shrode, Jennifer R. Duncan, Wendy Holliday

Flora Shrode

Librarians from Utah State University explain recent efforts to encourage subject librarians to take a more holistic view of their roles. We are shifting from a traditional emphasis primarily on collection development and refocusing on natural connections between collections, instruction, liaison, and reference service. The poster provides background about Utah State University’s situation and explains our approach to analyzing local needs and culture to inform development of a new organizational structure. We describe our vision of subject librarianship, the process by which we assessed librarians’ ideas and goals for performing as subject librarians, and the actions we are taking to …

Duskside F-Region Dynamo Currents: Itsrelationship With Prereversal Enhancement Of Vertical Plasma Drift, P. Park, H. Luhr, Bela G. Fejer, K. W. Mim

Bela G. Fejer

From magnetic field observations by CHAMP we estimate F-region dynamo current densities near the sunset terminator during solar maximum years from 2001 to 2002. The dynamo currents are compared with the pre-reversal enhancement (PRE) of vertical plasma drift as observed by ROCSAT-1. The seasonal-longitudinal variation of PRE can be largely related to the F-region dynamo current density, with the correlation coefficient reaching 0.74. The correlation can be further improved if we consider a zonal gradient of the E-region Pedersen conductivity, which also depends on season and longitude. It is widely accepted that the Fregion dynamo drives PRE near sunset. For …

Lunar Dependent Equatorial Ionospheric Effects During Sudden Stratosphericwarmings, Bela G. Fejer, M. E. Olson, J. L. Chau, C. Stolle, H. Luhr, L. P. Goncharenko, K. Yumoto, T. Nagatsuma

Bela G. Fejer

[1] We have used plasma drift and magnetic field measurements during the 2001–2009 December solstices to study, for the first time, the longitudinal dependence of equatorial ionospheric electrodynamic perturbations during sudden stratospheric warmings. Jicamarca radar measurements during these events show large dayside downward drift (westward electric field) perturbations followed by large morning upward and afternoon downward drifts that systematically shift to later local times. Ground-based magnetometer measurements in the American, Indian, and Pacific equatorial regions show strongly enhanced electrojet currents in the morning sector and large reversed currents (i.e., counterelectrojets) in the afternoon sector with onsets near new and full …

Quiet Variability Of Equatorial E × B Drifts During A Sudden Stratospheric Warning Event, J. L. Chau, Bela G. Fejer, L. P. Goncharenko

Bela G. Fejer

[1] We present strong evidence that during the January 2008 minor sudden stratospheric warming (SSW) event, the equatorial vertical E × B drifts exhibit a unique and distinctive daytime pattern. We do not think one event causes the other, however both events might be related through the global effects of planetary waves. The drifts were measured by the Jicamarca Incoherent scatter radar located under the magnetic equator. We have observed an anomalous temporal variation of the vertical E × B drifts during the minor SSW event, showing a semidiurnal variation with very large amplitudes lasting for several days. Large differences …

Climatology Of Early Night Equatorial Spread F Over Jicamarca, N. P. Chapagain, Bela G. Fejer

Bela G. Fejer

[1] We use radar observations from 1996 to 2006 to study the climatology of postsunset equatorial 3-m spread F irregularities over Jicamarca during all seasons. We show that the spread F onset times do not change with solar flux and that their onset heights, which occur near the altitude of the evening F region velocity vortex, increase linearly from about 260 to 400 km from solar minimum to solar maximum. Higher onset heights generally lead to stronger radar echoes. During the equinox, spread F onset occurs near vertical drift evening reversal times, while during the December solstice, they occur near …

Arkosic Rocks From The San Andreas Fault Observatory At Depth (Safod)Borehole, Central California, S. D. Springer, J. P. Evans, J. I. Garver, D. Kirschner, Susanne U. Janecke

Susanne U. Janecke

http://lithosphere.geoscienceworld.org/content/1/4/206 The San Andreas Fault Observatory at Depth (SAFOD) drill hole encountered indurated, high-seismic-velocity arkosic sedimentary rocks west of the active trace of the San Andreas fault in central California. The arkosic rocks are juxtaposed against granitic rocks of the Salinian block to the southwest and against fine-grained Great Valley Group and Jurassic Franciscan rocks to the northeast. We identify three distinct lithologic units using cuttings, core petrography, electrical resistivity image logs, zircon fission-track analyses, and borehole-based geophysical logs. The upper arkose occurs from 1920 to 2530 m measured depth (mmd) in the borehole and is composed of five structural …

Overviewand Summary Of The Spread F Experiment (Spreadfex), D. C. Fritts, M. A. Abdu, B. R. Batista, I. S. Batista, P. P. Batista, R. Buritii, B. R. Clemesha, J. Comberiate, T. Dautermann, E. De Paula, B. J. Fechine, Bela G. Fejer, D. Gobbi, J. Haase, F. Kalamabadi, B. Laughman, P. P. Lima, H. L. Liu, A. Medeiros, D. Pautet, F. Sao Sabbas, J. H.A. Sobral, P. Stamus, H. Takahashi, M. J. Taylor, S. L. Vadas, C. Wrasse

Bela G. Fejer

We provide here an overview of, and a summary of results arising from, an extensive experimental campaign (the Spread F Experiment, or SpreadFEx) performed from September to November 2005, with primary measurements in Brazil. The motivation was to define the potential role of neutral atmosphere dynamics, specifically gravity wave motions propagating upward from the lower atmosphere, in seeding Rayleigh-Taylor instability (RTI) and plasma bubbles extending to higher altitudes. Campaign measurements focused on the Brazilian sector and included ground-based optical, radar, digisonde, and GPS measurements at a number of fixed and temporary sites. Related data on convection and plasma bubble structures …

Gathering Leadership Momentum Across Great Distances: Creating An Online Community Of Practice, Erin L. Davis, Danielle Theiss-White

Erin Davis

At the 2007 Mountain Plains Library Association Leadership (MPLA) Institute, held in New Mexico, USA, eight academic librarians formed an online multi-state, multigenerational community of practice. MPLA is a twelve-state library association within the United States. Using Google Groups™, the members formed an online environment called the MPLA Community of Practice for continuing development of the leadership skills presented at the Institute. These early-career librarians represent diverse educational backgrounds and work in libraries serving varied populations with differing disciplinary emphases.

The group meets monthly with each member preparing and facilitating online discussions, complete with personal assessments, topical readings, and questions. …

Seasonal And Longitudinal Dependence Of Equatorialdisturbance Vertical Plasma Drifts, Bela G. Fejer, J. W. Jensen, S. Y. Su

Bela G. Fejer

[1] We used equatorial measurements from the ROCSAT-1 satellite to determine the seasonal and longitudinal dependent equatorial F region disturbance vertical plasma drifts. Following sudden increases in geomagnetic activity, the prompt penetration vertical drifts are upward during the day and downward at night, and have strong local time dependence at all seasons. The largest prompt penetration drifts near dusk and dawn occur during June solstice. The daytime disturbance dynamo drifts are small at all seasons. They are downward near dusk with largest (smallest) values during equinox (June solstice); the nighttime drifts are upward with the largest magnitudes in the postmidnight …

Quiet Time Equatorial F Region Vertical Plasma Drift Model Derived From Rocsat-1 Observations, Bela G. Fejer, J. W. Jensen, S. Y. Su

Bela G. Fejer

[1] We have used five years of measurements on board the ROCSAT-1 satellite to develop a detailed quiet time global empirical model for equatorial F region vertical plasma drifts. This model describes the local time, seasonal and longitudinal dependence of the vertical drifts for an altitude of 600 km under moderate and high solar flux conditions. The model results are in excellent agreement with measurements from the Jicamarca radar and also from other ground-based and in situ probes. We show that the longitudinal dependence of the daytime and nighttime vertical drifts is much stronger than reported earlier, especially during December …

F3 Layerduring Penetration Electric Field, N. Balan, H. Alleyne, S. V. Thampi, K. Lynn, Y. Otsuka, Bela G. Fejer, M. A. Abdu

Bela G. Fejer

[1] The occurrence of an additional layer, called F3 layer, in the equatorial ionosphere at American, Indian, and Australian longitudes during the super double geomagnetic storm of 7–11 November 2004 is presented using observations and modeling. The observations show the occurrence, reoccurrence, and quick ascent to the topside ionosphere of unusually strong F3 layer in Australian longitude during the first super storm (8 November) and in Indian longitude during the second super storm (10 November), all with large reductions in peak electron density (Nmax) and total electron content (GPS-TEC). The unusual F3 layers can arise mainly from unusually strong fluctuations …

Relation Between The Occurrence Rate Of Esf And The Verticalplasma Drift Velocity At Sunset Derived Form Global Observations, C. Stolle, H. Luhr, Bela G. Fejer

Bela G. Fejer

In this study, we investigate two global climatological data sets; the occurrence rate of Equatorial Spread- F (ESF), associated with equatorial plasma irregularities, at 400 km altitude obtained from CHAMP observations, and the evening equatorial vertical plasma drift, vz, from ROCSAT-1 measurements. First, as retrieved for a solar flux level of F10.7=150, the longitudinal variation of the two independently derived quantities correlates between 84% and 93% in the seasons December solstice, equinox and June solstice. The highest correlation is found for the solstice seasons when vz is integrated over local time around the prereversal enhancement (PRE) and displaced 6 towards …

Gravity Wave And Tidalinfluences On Equatorial Spread F Based On Observations During The Spread F Experiment(Spreadfex), D. C. Fritts, S. L. Vadas, D. M. Riggin, M. A. Abdu, I. S. Batista, H. Takahashi, A. Medeiros, F. Kalamabadi, H. L. Liu, Bela G. Fejer, M. J. Taylor, F. Vargas

Bela G. Fejer

The Spread F Experiment, or SpreadFEx, was performed from September to November 2005 to define the potential role of neutral atmosphere dynamics, primarily gravity waves propagating upward from the lower atmosphere, in seeding equatorial spread F (ESF) and plasma bubbles extending to higher altitudes. A description of the SpreadFEx campaign motivations, goals, instrumentation, and structure, and an overview of the results presented in this special issue, are provided by Fritts et al. (2008a). The various analyses of neutral atmosphere and ionosphere dynamics and structure described in this special issue provide enticing evidence of gravity waves arising from deep convection in …

Eocene To Oligocene Provenance And Drainage In Extensional Basinsof Southwest Montana And East-Central Idaho, C. N. Stroup, P. K. Link, Susanne U. Janecke, C. M. Fanning, G. M. Yaxley

Susanne U. Janecke

No abstract provided.

Early Pleistocene Initiation Andstructural Complexity Of The San Jacinto And San Felipe Fault Zones, Susanne U. Janecke, R. J. Dorsey, B. Belgarde

Susanne U. Janecke

No abstract provided.

Age And Structure Of The Sanjacinto And San Felipe Fault Zones, And Their Lifetime Slip Rates, Susanne U. Janecke, R. J. Dorsey, B. Belgarde

Susanne U. Janecke

No abstract provided.

Equatorial Ionospheric Electric Fields During The November 2004 Magnetic Storm, Bela G. Fejer, J. W. Jensen, T. Kikuchi, M. A. Abdu, J. L. Chau

Bela G. Fejer

[1] We use radar measurements from the Jicamarca Radio Observatory, magnetometer observations from the Pacific sector and ionosonde data from Brazil to study equatorial ionospheric electric fields during the November 2004 geomagnetic storm. Our data show very large eastward and westward daytime electrojet current perturbations with lifetimes of about an hour (indicative of undershielding and overshielding prompt penetration electric fields) in the Pacific equatorial region during the November 7 main phase of the storm, when the southward IMF, the solar wind and reconnection electric fields, and the polar cap potential drops had very large and nearly steady values. This result …

Continuous Laser‐Excited Photothermal Spectrometry Of CdsXSe1‐X Doped Glasses, Oluwatosin Dada, Matthew R. Jorgensen, Stephen E. Bialkowski

Stephen E. Bialkowski

Photothermal lens measurements and finite element modeling are used to examine the physical changes taking place in optical filter glasses. Colored glass and neutral density filters are found to have a strong positive temperature-dependent refractive index change. The overall positive refractive index change is thought to be a consequence of complex counteracting factors: stress-induced birefringence, polarizability, structural network, and temperature-dependent carrier density changes in the CdS_xSe_1–x microcrystals that produce optical properties of these glasses. Finite element analysis (FEA) modeling is used to examine the temperature profiles and the goodness of the semi-infinite thermal diffusion solution normally used …

Longitudinal Dependence Of Middle And Low Latitude Zonal Plasmadrifts Measured By De-2, J. Jensen, Bela Fejer

Bela G. Fejer

We used ion drift observations from the DE-2 satellite to study for the first time the longitudinal variations of middle and low latitude F region zonal plasma drifts during quiet and disturbed conditions. The quiet-time middle latitude drifts are predominantly westward; the low latitude drifts are westward during the day and eastward at night. The daytime quiet-time drifts do not change much with longitude; the nighttime drifts have strong season dependent longitudinal variations. In the dusk-premidnight period, the equinoctial middle latitude westward drifts are smallest in the European sector and the low latitude eastward drifts are largest in the American-Pacific …

Low-Temperature Charge Transport In Ga-Acceptor Nanowires Implanted By Focused-Ion Beams, S. J. Robinson, C. L. Perkins, T. -C. Shen, J. R. Tucker, T. Schenkel, X. W. Wang, T. P. Ma

T. -C. Shen

Ga-acceptor nanowires were embedded in crystalline Si using focused-ion beams. The dc current-voltage characteristics of these wires after annealing are highly nonlinear at low temperatures. A conductance threshold of less than 50mV is observed independent of Ga⁺ dosage and implant beam overlap. These features suggest a Coulomb blockade transport mechanism presumably caused by a network of Ga precipitates in the substrate. This granular scenario is further supported by measurements of gated nanowires. Nanowires with metallic conductance at low temperatures could be achieved by reducing the current density of the focused-ion beams.

Discontinuities In Stream Nutrient Uptake Below Lakesin Mountain Drainage Networks, Michelle A. Baker

Michelle A. Baker

In many watersheds, lakes and streams are hydrologically linked in spatial patterns that influence material transport and retention. We hypothesized that lakes affect stream nutrient cycling via modifications to stream hydrogeomorphology, source‐waters, and biological communities. We tested this hypothesis in a lake district of the Sawtooth Mountains, Idaho. Uptake of NO3− and PO4−3 was compared among 25 reaches representing the following landscape positions: lake inlets and outlets, reaches >1‐km downstream from lakes, and reference reaches with no nearby lakes. We quantified landscape‐scale hydrographic and reach‐scale hydrogeomorphic, source‐water, and biological variables to characterize these landscape positions and analyze relationships to nutrient …

Cenozoic Extensional Processes And Tectonics In The Northern Rocky Mountains, Susanne U. Janecke

Susanne U. Janecke

Extension has shaped the crust of the Northern Rocky Mountains for more than a billion years. Rifting produced the Belt basin shortly after 1.5 Ga and initiated the Paleozoic passive margin. Mesozoic to early Cenozoic convergence pro-duced the Cordilleran fold-and-thrust belt, the uplifts of the Rocky Mountain foreland (Laramide) and an unusually broad Challis arc in the northern Rocky Mountains. The struc-tural grain of the contractional belts, basement features, and the rheology of the Idaho batho-lith influenced the locus, kinematics and ge-ometry of the >55 m.y. of extension that fol-lowed. Sparse data suggest that extension may have begun in the …

Evolution Of Equatorial Ionospheric Bubbles During A Large Auroral Electrojet Increase In The Recovery Phase Of A Magnetic Storm, M. J. Keskinen, S. L. Ossakow, Bela G. Fejer, J. Emmert

Bela G. Fejer

[1] We present a model and observations of the evolution of equatorial ionospheric bubbles during a large auroral electrojet (AE) index increase in the recovery phase of a geomagnetic storm. Using a three-dimensional time-dependent numerical simulation model, we find, for the 19–21 October 1998 storm, that the equatorial bubble evolution is different during storm time as compared to quiet time conditions. We have found that the storm time vertical drift in conjunction with reduced off-equatorial E region shorting is the primary mechanism that distinguishes the large AE increase recovery phase storm time evolution from the quiet time case. Comparison of …

Electron Transport In Laterally Confined Phosphorus Δ-Layers In Silicon, S. J. Robinson, J. S. Kline, H. J. Wheelwright, J. R. Tucker, C. L. Yang, R. R. Du, B. E. Volland, I. W. Rangelow, T. -C. Shen

T. -C. Shen

Two-dimensional electron systems fabricated from a single layer of P-donors have been lithographically confined to nanometer scale in lateral directions. The electronic transport of such quasi-one-dimensional systems with and without a perpendicular magnetic field was characterized at cryogenic temperatures. Experimental data fit well with two-dimensional weak localization and interaction theory when the phase coherence length is shorter than the smaller dimension of the confinement. Below a transition temperature the wire conductance saturates.

Climatology Of F Region Zonalplasma Drifts Over Jicamarca, Bela G. Fejer, J. R. Souza, A. S. Santos, A. E. Costa Pereira

Bela G. Fejer

[1] We use extensive incoherent scatter radar observations made at the Jicamarca Radio Observatory between 1970 and 2003 to study and model empirically the equatorial zonal plasma drifts near the F region peak using Bernstein polynomials as base functions. Our quiet-time model results confirm that the daytime drifts are westward and are nearly season and solar cycle independent. The nighttime drifts are eastward, have larger magnitudes, and increase strongly with solar flux, particularly near equinox and December solstice. Enhanced geomagnetic activity drives small eastward perturbation drifts during the day and much larger westward disturbance drifts at night. The nighttime drift …

Assimilative Modeling Of The Equatorial Ionosphere For Scintillation Forecasting: Modeling With Vertical Drifts, J. M. Retterer, D. T. Decker, W. S. Borer, R. E. Daniell, Bela G. Fejer

Bela G. Fejer

[1] Knowledge of the vertical plasma drift velocity observed by the Jicamarca incoherent radar in seven events is assimilated into a theoretical model for the ambient F region plasma density. Comparisons of the calculated plasma density model and the observed plasma density show that, apart from the signature effects of equatorial plasma bubbles, the ambient model captures much of the detail of the plasma density profiles. Rayleigh-Taylor growth rates calculated with the ambient model show a good correlation with the occurrence of spread F.

Evolution Of A Late Cenozoic Supradetachment Basin Above A Flat-On-Flat Detachment With A Folded Lateral Ramp, Se Idaho, A. N. Steely, Susanne U. Janecke, S. P. Long, S. C. Carney, R. Q. Oaks Jr., V. E. Langenheim, P. K. Link

Susanne U. Janecke

Uplift and exposure of the Bannock detachment system and the synextensionalbasin fi ll deposits of the Salt Lake Formation provide a unique exposure of the threedimensionalgeometries of a low-angle normal fault system and the stratal architectureof the overlying supradetachment basin. Within this system, structural andstratigraphic analyses, outcrop patterns, tephra geochronology, and geological crosssections document several important relationships: (1) the Bannock detachment systemdeveloped above the Sevier-age Cache-Pocatello culmination and resembles theSevier Desert detachment in its geometry, structural setting, and kinematic evolution;(2) the Bannock detachment system initiated and slipped at low angles; (3) fl aton-fl at, ramp-fl at, and lateral ramp geometries, …

Average Nighttime F Region Disturbance Neutral Winds Measured By Windi Uars: Initial Results, J. T. Emmert, Bela G. Fejer, G. G. Shepard, B. H. Solheim

Bela G. Fejer

[1] We use low- and mid-latitude wind data from the Wind Imaging Interferometer (WINDII) on board the Upper Atmosphere Research Satellite (UARS) to study the average response of nighttime upper thermospheric winds to geomagnetic activity. We calculate perturbation winds in magnetic coordinates and analyze them as a function of magnetic local time, latitude, geomagnetic activity, and solar EUV flux. The nighttime zonal disturbance winds are predominately westward, with the strongest effects extending from dusk at 70° to midnight at 45°. Westward disturbance winds are also observed throughout most of the night at low latitudes, where they change to eastward at …