Bulletin of the American Physical Society
15th Annual Meeting of the Northwest Section of the APS
Volume 59, Number 6
Thursday–Saturday, May 1–3, 2014; Seattle, Washington
Session C4: Applied and Multidisciplinary Physics |
Hide Abstracts |
Chair: John Orrell, Pacific Northwest National Laboratory Room: Alder Commons 106 |
Friday, May 2, 2014 1:30PM - 2:00PM |
C4.00001: Measuring and Mitigating Ionospheric Effects on Global Navigation Satellite Systems Invited Speaker: Susan Skone Global Navigation Satellite Systems (GNSS) such as GPS are employed by many users worldwide for purposes of recreation, vehicle navigation, and safety-critical aviation marine and applications (to name a few). The GNSS signals experience propagation delays and attenuation in the Earth's ionosphere - resulting in degradation of signal quality and positioning accuracy. Such effects must be mitigated, particularly for safety-critical systems, to ensure continuous service and integrity to meet system specifications. This presentation describes some of the major limitations and solutions for mitigating challenging ionospheric effects on GNSS. Ground-based and space-borne GNSS receivers may allow direct calibration of ionospheric parameters and therefore exploitation of GNSS as an ionospheric remote sensing tool. Applications include space weather, ionospheric profiling using radio occultation measurements and detection of natural hazards such as earthquakes and tsunamis using GNSS estimates of ionospheric total electron content. In recent years the GPS has been modernized with new signals and system capabilities. Additional GNSS include Galileo, GLONASS, QZSS and Beidou. The new generation GNSS receivers have multi-constellation and multi-frequency capabilities. This presentation explores the tremendous opportunity for increased observability and estimation of ionospheric properties using GNSS. [Preview Abstract] |
Friday, May 2, 2014 2:00PM - 2:12PM |
C4.00002: Toward a Rebirth of Laboratory-Based XANES Gerald Seidler, Neil Ball, Devon Mortensen, Joseph Pacold As a consequence of the necessary scarcity of synchrotron beamtime, advanced x-ray spectroscopies are nearly unique in having both high scientific and technical importance but also extremely low user access. This dilemma excludes the use of such methods in a wide variety of industrial applications and also negatively impacts fundamental and applied research in energy sciences. Building upon recent results with an inexpensive, prototype system [G.T. Seidler, et al., submitted Rev. Sci. Instrum. 2014] we are designing and constructing a laboratory-based user facility for the measurement of x-ray absorption near edge structure (XANES) for the K-edges of the 3d transition metals. This system will maintain 1-eV energy resolution from 5 keV to 10 keV with flux as high as 10M/sec. As such, it will be substantially comparable to the performance at synchrotron x-ray beamlines for transmission-mode XANES studies in electrical energy storage and catalysis. We will discuss the technical details behind this instrument and the plans for its operation under the auspices of the new shared user facility being developed by the UW Clean Energy Institute (CEI). First light for the CEI-XANES facility is scheduled to occur late in the summer of 2014. [Preview Abstract] |
Friday, May 2, 2014 2:12PM - 2:24PM |
C4.00003: Design and Fabrication of Compact, Portable X-Pinch Driver Based on 2 LTD Bricks at the Idaho Accelerator Center Roman Shapovalov, Rick Spielman, Wendland Beezhold The compact and portable $x$-pinch driver able to supply of about 200-kA peak current with about 150-ns rise time was proposed recently\footnote{R.V. Shapovalov, R.B. Spielman, W. Beezhold, ``Design and Projected Performance of a Compact, Portable Plasma-Radiation-Source Generator at the Idaho Accelerator Center,'' abstract submitted to ICOPS/BEAMS, Washington DC (2014).} and currently under fabrication at the Idaho Accelerator Center. This driver will be able to produce a very unique $x$-ray radiation source, which could be used in many applications in physics,\footnote{S. A. Pikuz et al., Rev. Sci. Instrum. \textbf{68}, 740 (1997).}$^,$\footnote{T. A. Shelkovenko et al., Rev. Sci. Instrum. \textbf{70}, 667 (1999).}$^,$\footnote{S. A. Pikuz et al., Phys. Plasmas \textbf{6}, 4272 (1999).} biology,\footnote{B. M. Song et al., Nuclear Science Symposium Medical Imaging Conference, Norfolk, VA 2002, p. 868.} and radiography.\footnote{F. N. Beg et al., Appl. Phys. Let. \textbf{89}, 101502 (2006).} In this work we present the short-circuit test results of our compact and portable x-pinch driver. [Preview Abstract] |
Friday, May 2, 2014 2:24PM - 2:36PM |
C4.00004: Evidence for mass dependent sulfur isotope fractionation revealed by Multiple Collector Inductively Coupled Mass Spectrometry Yahya Alfayfi, Michael Wieser, M. Musiani, C. Dubesky The determination of the isotopic abundance of sulfur isotopes, in particular of S-33, using gas source mass spectrometry is complicated by the presence of oxygen isotopes and isotopologues of sulfurdioxide and the majority of the published studies report only S-33 isotope amount ratios. However, it is desirable to obtain S-33 data, which can provide important information on the nature of mass-dependent processes responsible for the cycling of sulfur. In this study, a high mass resolution MC-ICP-MS was used to measure the three most abundant stable isotopes of sulfur, free from oxygen interferences. The reliability of the analytical method was verified using the international reference materials from IAEA. In addition, hair samples collected from wild animals were measured for their sulfur isotopic composition as part of a large study to explore the diet of wolves in west central Alberta. The accuracy of the S-33 and S-34 isotope amount ratios should enable the elucidation of food sources in the region affected by industrial activities. [Preview Abstract] |
Friday, May 2, 2014 2:36PM - 2:48PM |
C4.00005: Partitioning of copper isotopes reveals changes in metabolism due to prion protein expression in transgenic mice Kerri Miller, Catherine M. Keenan, Gary R. Martin, Keith A. Sharkey, Frank R. Jirik, Michael Wieser The partitioning of copper isotopes has provided a wealth of information regarding metal interactions in physical systems. Metabolic activities in animals can partition copper isotopes as the metal is assimilated into the body. Therefore variations in copper isotope abundances in organs and tissues may act as a biomarker for changes in metabolism and may vary in disease. Prion protein is a naturally occurring copper binding protein of importance in neurodegenerative conditions. Mice that lack prion, over express this protein and lack the copper binding motif are available and we used these animals to investigate whether changes in copper isotopic composition were present in the organs and tissues of these mice. The copper isotope amount ratios were measured using an MC-ICP-MS. Changes in the copper isotope amount ratios due to the presence of this protein or its ability to bind copper were observed, most notably in the kidneys and the colon. These results suggest that isotope abundance data may be an innovative tool for identifying alterations in biological homeostasis and may provide novel diagnostic approaches in disease. [Preview Abstract] |
Friday, May 2, 2014 2:48PM - 3:00PM |
C4.00006: Modern challenges and progress in the measurement of the atomic weights of the elements Adam Mayer, Michael Wieser Throughout history, the atomic weights of the elements had been regarded as constants of nature. However, in the late 1930s it was discovered that the atomic weights of some elements could vary naturally, either by radioactivity or by physical and chemical processes. This can lead to challenges in determining, and even defining, the atomic weight to an element. How do you define the weight of an element, when different samples have different weights? In this talk, I will discuss these challenges and how they are addressed by the International Union of Pure and Applied Chemistry when they publish the table of Atomic Weights. I will discuss the natural variability among some elements and how this variability changes how the atomic weight can be defined. I will also discuss how measurement bias can affect results, and how modern measurement techniques are used to correct the measurement biases based on reference materials traceable to organizations such as the National Institute of Standards and Technology. I will center this discussion around my own recently accepted atomic weight measurement for Molybdenum, which was referenced in the September 2013 issue of Popular Science. [Preview Abstract] |
Friday, May 2, 2014 3:00PM - 3:27PM |
C4.00007: Break
|
Friday, May 2, 2014 3:27PM - 3:57PM |
C4.00008: The Quantification of Auroral Patches: Musings of a Neuroscientist Invited Speaker: Simon Spanswick The aurora is a consequence of processes occurring in the near-Earth space environment. Details about auroral structure and behavior can provide clues about plasma processes occurring in regions of space that are rarely sampled by spacecraft. By using the aurora to indirectly measure aspects of plasma dynamics we can gain a system-level snapshot that would not otherwise be observable. One common type of aurora is patchy aurora, which refers to irregularly shaped ``blobs'' that form a characteristic patch pattern in auroral image data.~Patches are most often observed at mid- to low-auroral latitudes, equatorward of the peak in the proton aurora. One of the remarkable features of patchy aurora is the apparent coherent and relatively consistent shape of the patches, which can be present for minutes at a time in the field of view of a single all-sky camera. The structure of an individual patch is often maintained as it drifts in longitude through a camera field of view.~This behavior is thought to be a consequence of both plasma dynamics and structure in the region Earthward of the central plasma sheet. Here we describe a cross-disciplinary approach to quantifying auroral patches.~Statistics are derived from a collaboration between the fields of neuroscience and space physics.~Specifically, we employ a modified stereological approach to quantify length and orientation of patchy aurora. Stereological quantification has been successfully employed within the neurosciences to estimate the length, volume, or number of objects within a specific region of interest. One of the central tenets of stereology is the random, systematic sampling method, which has been demonstrated as both highly accurate and efficient. We adopt a modified stereological procedure, using random, systematic sampling to produce an unbiased estimate of patch length and orientation within the aurora.~ The output of this procedure can also be adapted to follow individual~patches and produce velocity fields in a given image.~These techniques allow us to quantify the evolution of both individual patches, and the patchy aurora region as a whole. We also discuss the future possibility of using this technique to produce a semi-automated convection map for specific events. We assert that these maps will provide a time-evolving picture of the 2D convection velocity in the ionosphere with excellent spatial and temporal resolution. [Preview Abstract] |
Friday, May 2, 2014 3:57PM - 4:09PM |
C4.00009: Molybdenum as a tracer to anthropogenic activity Alexander Tennant, Stephen Lane, Bernadette Proemse, Michael Wieser The trace metal molybdenum (Mo) is not very abundant in the environment, but has numerous applications in anthropogenic activities. For instance, Mo sulphide (MoS$_2$) is a component of diesel fuel. Mo is used as a catalyst in many engines and is believed to be the most efficient catalyst for the hydro-cracking of bitumen, and has even been found in the emissions of coal-fired power plants. Hence, anthropogenic activities may release Mo in larger amounts to the environment that may affect terrestrial and aquatic ecosystems (e.g. via its coupling with the N cycle). We have therefore investigated the potential of Mo concentration and isotopic abundances as a tracer of androgenic emissions. Using a method of elemental double spiking, we measured Mo concentrations and isotopic composition of aerosols throughout the city of Calgary, Alberta, Canada. Airborne Mo was collected at several locations, ranging from an isolated weather station to a busy bus garage where buses were left to idle for extended periods of time. Mo concentrations ranged from 0.07 ng/m$^3$ in the laboratory 19.0 ng/m$^3$ in the bus garage. The isotopic compositions were variable from throughout the sampling sites. These results suggest that Mo has the potential to be used as a tracer of anthropogenic activity. [Preview Abstract] |
Friday, May 2, 2014 4:09PM - 4:21PM |
C4.00010: Developing Analytical Technique to Measure Stable and Radiogenic Strontium Isotope Ratios Using Thermal Ionization Mass Spectrometry with a Sr Double Spike Method (TIMS-DS) Nadia Elhamel, Michael Wieser Variation in strontium isotope abundances is caused by mass dependent physical and chemical processes and the radiogenic decay of $^{87}$Rb to $^{87}$Sr. Up to now, most isotope abundance determinations have focused on the n($^{87}$Sr)/n($^{86}$Sr) ratio. It was assumed that changes in the n ($^{88}$Sr)/n ($^{86}$Sr) ratios would be very small. In addition, the custom has been to ignore variations in n($^{88}$Sr)/n($^{86}$Sr) ratios by assuming a fixed ratio, which was necessary to correct for instrumental mass biases. Recently, however, it was observed that small, but significant variations in the relative amounts of the non-radiogenic isotopes could have applications in geochemistry and archaeology. Therefore, an analytical method using a strontium double spike was developed to measure the both ratios on TIMS. Using this technique, the results obtained for the SRM987 reference material are in agreement with published data. However, IAPSO sea water standard measurement revealed an enrichment in the n($^{88}$Sr)/n($^{86}$Sr) ratio relative to SRM987 of 0.04 {\%} and an accurate n($^{87}$Sr)/n($^{86}$Sr) ratio of 0.709325(27), which is significantly different from the n($^{87}$Sr)/n($^{86}$Sr) ratio of 0.709191(37), which is found when assuming a fixed ratio. The use of a double spike method for measuring strontium isotopic composition will reveal important insights into mass dependent processes that occur as this element moves through a particular system as well as provide accurate data for the radiogenic strontium isotope ratio. [Preview Abstract] |
Friday, May 2, 2014 4:21PM - 4:33PM |
C4.00011: Identification of geographical origins of exotic wood using $^{87}$Sr/$^{86}$Sr isotope ratios as a forensic tool Amanda Kiilerich, Kerri Miller, Haiping Qi, Tyler Coplen, Michael Wieser Exotic rosewood species of the Amazon rainforest have desirable properties that have made them valuable for commercial use. Unsustainable logging has resulted in overexploitation. In effort to protect the endangered species they are illegal to trade and controlled by the Washington Convention (CITES). Despite united efforts of international trade officials to prevent trade and export of the species it is still an ongoing business. The goal of this study is to use variations in isotopic composition of strontium to assist in the identification of the geographical origin of wood samples. This can be used to target illegally logged wood and aid the effort to prevent the trade. The $^{87}$Sr/$^{86}$Sr isotope amount ratios in 25 samples have been analyzed using thermal ionization mass spectrometry. The samples were identified by their species and country of origin. The result of this study is the most recent expansion of a database consisting of more than 250 samples with ratios between 0.704174(4) and 0.790396(3) with typical external reproducibilities of the order 10 ppm. Of the different geographical locations represented by the set of samples many exhibit distinct isotopic fingerprints that facilitate the strontium isotopic abundances as a forensic tool. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700