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Portland State University

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2017

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Full-Text Articles in Physical Sciences and Mathematics

The Effect Of Rare Variants In Trem2 And Pld3 On Longitudinal Cognitive Function In The Wisconsin Registry For Alzheimer's Prevention, Corinne D. Engelman, Burcu F. Darst, Murat Bilgel, Eva Vasiljevic, Rebecca L. Koscik, Bruno M. Jedynak, Sterling C. Johnson Dec 2017

The Effect Of Rare Variants In Trem2 And Pld3 On Longitudinal Cognitive Function In The Wisconsin Registry For Alzheimer's Prevention, Corinne D. Engelman, Burcu F. Darst, Murat Bilgel, Eva Vasiljevic, Rebecca L. Koscik, Bruno M. Jedynak, Sterling C. Johnson

Mathematics and Statistics Faculty Publications and Presentations

Recent studies have found an association between functional variants in TREM2 and PLD3 and Alzheimer's disease (AD), but their effect on cognitive function is unknown. We examined the effect of these variants on cognitive function in 1449 participants from the Wisconsin Registry for Alzheimer's Prevention, a longitudinal study of initially asymptomatic adults, aged 36–73 years at baseline, enriched for a parental history of AD. A comprehensive cognitive test battery was performed at up to 5 visits. A factor analysis resulted in 6 cognitive factors that were standardized into z scores (∼N [0, 1]); the mean of these z scores was …


Classification Of Minimal Separating Sets In Low Genus Surfaces, J. J. P. Veerman, William Maxwell, Victor Rielly, Austin K. Williams Dec 2017

Classification Of Minimal Separating Sets In Low Genus Surfaces, J. J. P. Veerman, William Maxwell, Victor Rielly, Austin K. Williams

Mathematics and Statistics Faculty Publications and Presentations

Consider a surface S and let MS. If S \ M is not connected, then we say M separates S, and we refer to M as a separating set of S. If M separates S, and no proper subset of M separates S, then we say M is a minimal separating set of S. In this paper we use computational methods of combinatorial topology to classify the minimal separating sets of the orientable surfaces of genus g = 2 and g = 3. The classification for genus 0 and 1 was done …


Variational Geometric Approach To Generalized Differential And Conjugate Calculi In Convex Analysis, Boris S. Mordukhovich, Nguyen Mau Nam, R. Blake Rector, T. Tran Dec 2017

Variational Geometric Approach To Generalized Differential And Conjugate Calculi In Convex Analysis, Boris S. Mordukhovich, Nguyen Mau Nam, R. Blake Rector, T. Tran

Mathematics and Statistics Faculty Publications and Presentations

This paper develops a geometric approach of variational analysis for the case of convex objects considered in locally convex topological spaces and also in Banach space settings. Besides deriving in this way new results of convex calculus, we present an overview of some known achievements with their unified and simplified proofs based on the developed geometric variational schemes. Key words. Convex and variational analysis, Fenchel conjugates, normals and subgradients, coderivatives, convex calculus, optimal value functions.


Confined Photonic Mode Propagation Observed In Photoemission Electron Microscopy, Theodore Stenmark, Robert Campbell Word, Rolf Konenkamp Dec 2017

Confined Photonic Mode Propagation Observed In Photoemission Electron Microscopy, Theodore Stenmark, Robert Campbell Word, Rolf Konenkamp

Physics Faculty Publications and Presentations

Using photoemission electron microscopy (PEEM) we present a comparative analysis of the wavelength dependence of propagating fields in a simple optical slab waveguide and a thin film photonic crystal W1-type waveguide. We utilize an interferometric imaging approach for light in the near-ultraviolet regime where a 2-photon process is required to produce photoelectron emission. The typical spatial resolution in these experiments is < 30 nm. Electromagnetic theory and finite element simulations are shown to be in good agreement with the experimental observations. Our results indicate that multiphoton PEEM is a useful sub-wavelength characterization technique in thin film optics.


Managing Herbicide Resistance: Listening To The Perspectives Of The Practitioners, Jill Schroeder, David Shaw, Michael Barrett, Harold Coble, Amy Asmus, Raymond Jussaume, David E. Ervin Dec 2017

Managing Herbicide Resistance: Listening To The Perspectives Of The Practitioners, Jill Schroeder, David Shaw, Michael Barrett, Harold Coble, Amy Asmus, Raymond Jussaume, David E. Ervin

Economics Faculty Publications and Presentations

No abstract provided.


Multiple Methods Of Public Engagement: Disaggregating Socio-Spatial Data For Environmental Planning In Western Washington, Usa, Rebecca J. Mclain, David Banis, Alexa Todd, Lee Cerveny Dec 2017

Multiple Methods Of Public Engagement: Disaggregating Socio-Spatial Data For Environmental Planning In Western Washington, Usa, Rebecca J. Mclain, David Banis, Alexa Todd, Lee Cerveny

Geography Faculty Publications and Presentations

Highlights

• The effectiveness of participatory GIS approaches at engaging different publics was explored.

• Online surveys engaged urbanites; community workshops engaged rural residents.

• Urban and rural residents went to similar places but engaged in different activities.

• Use of multiple data collection methods will broaden public engagement.

• Mapping behavior studies are needed to improve understandings of PPGIS data quality.


Entropy Production And Volume Contraction In Thermostated Hamiltonian Dynamics, John D. Ramshaw Nov 2017

Entropy Production And Volume Contraction In Thermostated Hamiltonian Dynamics, John D. Ramshaw

Physics Faculty Publications and Presentations

Patra et al. [Int. J. Bifurcat. Chaos 26, 1650089 (2016)] recently showed that the time-averaged rates of entropy production and phase-space volume contraction are equal for several different molecular dynamics methods used to simulate nonequilibrium steady states in Hamiltonian systems with thermostated temperature gradients. This equality is a plausible statistical analog of the second law of thermodynamics. Here we show that those two rates are identically equal in a wide class of methods in which the thermostat variables z are determined by ordinary differential equations of motion (i.e., methods of the Nosé-Hoover or integral feedback control type). This …


Mixing Times Of Organic Molecules Within Secondary Organic Aerosol Particles: A Global Planetary Boundary Layer Perspective, Adrian M. Maclean, Christopher L. Butenhoff, James W. Grayson, Kelley Barsanti, Jose L. Jimenez, Allan K. Bertram Nov 2017

Mixing Times Of Organic Molecules Within Secondary Organic Aerosol Particles: A Global Planetary Boundary Layer Perspective, Adrian M. Maclean, Christopher L. Butenhoff, James W. Grayson, Kelley Barsanti, Jose L. Jimenez, Allan K. Bertram

Physics Faculty Publications and Presentations

When simulating the formation and life cycle of secondary organic aerosol (SOA) with chemical transport models, it is often assumed that organic molecules are well mixed within SOA particles on the timescale of 1 h. While this assumption has been debated vigorously in the literature, the issue remains unresolved in part due to a lack of information on the mixing times within SOA particles as a function of both temperature and relative humidity. Using laboratory data, meteorological fields, and a chemical transport model, we estimated how often mixing times are < 1 h within SOA in the planetary boundary layer (PBL), the region of the atmosphere where SOA concentrations are on average the highest. First, a parameterization for viscosity as a function of temperature and RH was developed for α-pinene SOA using room-temperature and low-temperature viscosity data for α-pinene SOA generated in the laboratory using mass concentrations of ∼ 1000 µg m−3. Based on this parameterization, the mixing times within α-pinene SOA are < 1 h for 98.5 % and 99.9 % of the occurrences in the PBL during January and July, respectively, when concentrations are significant (total organic aerosol concentrations are > 0.5 µg m−3 at the surface). Next, as a starting …


Deconstruction In Portland: Summary Of Activity, Emma Willingham, Peter Hulseman, Mike Paruszkiewicz Nov 2017

Deconstruction In Portland: Summary Of Activity, Emma Willingham, Peter Hulseman, Mike Paruszkiewicz

Northwest Economic Research Center Publications and Reports

On October 31st, 2016, the City of Portland instituted an ordinance requiring the deconstruction of all residential homes and duplexes built prior to 1917 or possessing a historical designation. Deconstruction is a relatively new industry, and with this local regulatory encouragement, several new contractors became certified to participate in the expanded market. This report provides background on the industry, largely from the 2016 report researched and written by the Northwest Economic Research Center (NERC) in anticipation of the requirement, and an examination of what has occurred in the year following the ordinance’s passage, using deconstruction and demolition permit data and …


Northwest Forest Plan The First 20 Years (1994-2013): Watershed Condition Status And Trend, Stephanie A. Miller, Sean N. Gordon, Peter Eldred, Ronald M. Beloin, Steve Wilcox, Mark Raggon, Heidi Andersen, Ariel Muldoon Nov 2017

Northwest Forest Plan The First 20 Years (1994-2013): Watershed Condition Status And Trend, Stephanie A. Miller, Sean N. Gordon, Peter Eldred, Ronald M. Beloin, Steve Wilcox, Mark Raggon, Heidi Andersen, Ariel Muldoon

Institute for Sustainable Solutions Publications and Presentations

We used two data sets to evaluate stream and upslope/riparian condition for sixth-field watersheds in each aquatic province within the Northwest Forest Plan (NWFP) area. The stream evaluation was based on stream sampling data collected from 2002 to the 2013 (214 watersheds) as part of an eight year repeating (rotating) sample design. We are currently halfway through our second rotation of stream sampling, and have repeated 110 watersheds since the second rotation began in 2009. The analysis presented in this report uses roughly half the number of watersheds as was originally intended by the sample design since re-visitation will not …


Building Planner Commitment: Are California’S Sb 375 And Oregon’S Sb 1059 Models For Climate-Change Mitigation?, Keith Bartholomew, David Proffitt Nov 2017

Building Planner Commitment: Are California’S Sb 375 And Oregon’S Sb 1059 Models For Climate-Change Mitigation?, Keith Bartholomew, David Proffitt

TREC Final Reports

California’s Sustainable Communities and Climate Protection Act (SB 375) and the Oregon Sustainable Transportation Initiative (SB 1059) have made them the first states in the nation to try and reduce greenhouse gas (GHG) emissions using the transportation-planning process. Evaluating how these pioneering laws have changed local planning processes – as well as plans themselves – in each state provides insight into the laws’ effectiveness at changing development patterns in a way that reduces GHG emissions, without waiting decades to see the effects in the built environment. Both states’ laws require metropolitan planning organizations (MPOs) and the municipalities that comprise them …


Using The Planning Process To Mitigate Climate Change, Keith Bartholomew Nov 2017

Using The Planning Process To Mitigate Climate Change, Keith Bartholomew

TREC Project Briefs

This research evaluates how Oregon’s SB 1059 and California’s SB 375 have integrated climate change mitigation strategies into local planning processes, and seeks to understand how transportation planning can help slow climate change.


Accessing Blue Spaces: Social And Geographic Factors Structuring Familiarity With, Use Of, And Appreciation Of Urban Waterways, Melissa Haeffner, Douglas Jackson-Smith, Martin Buchert, Jordan Risley Nov 2017

Accessing Blue Spaces: Social And Geographic Factors Structuring Familiarity With, Use Of, And Appreciation Of Urban Waterways, Melissa Haeffner, Douglas Jackson-Smith, Martin Buchert, Jordan Risley

Environmental Science and Management Faculty Publications and Presentations

Are urban waterways amenities, and if so, are there inequities in household access? While urban waterways represent a potential site for access to nature within the urban environment, there have been few studies on the accessibility and interactions with water features in particular, what we refer to as “blue spaces." This study drew on a sample of households in Northern Utah living in neighborhoods with a nearby river or canal to ask if local waterways provide positive impacts to households and if proximity to them increased the likelihood of households spending time at them and being familiar with them. We …


Ion Transport Across Biological Membranes By Carborane-Capped Gold Nanoparticles, Marcin P. Grzelczak, Stephen P. Danks, Robert C. Klipp, Domagoj Belic, Adnana Zaulet, Casper Kunstmann-Olsen, Dan F. Bradley, Tatsuya Tsukuda, Clara ViñAs, Francesc Teixidor, Jonathan J. Abramson, Mathias Brust Nov 2017

Ion Transport Across Biological Membranes By Carborane-Capped Gold Nanoparticles, Marcin P. Grzelczak, Stephen P. Danks, Robert C. Klipp, Domagoj Belic, Adnana Zaulet, Casper Kunstmann-Olsen, Dan F. Bradley, Tatsuya Tsukuda, Clara ViñAs, Francesc Teixidor, Jonathan J. Abramson, Mathias Brust

Physics Faculty Publications and Presentations

Carborane-capped gold nanoparticles (Au/carborane NPs, 2–3 nm) can act as artificial ion transporters across biological membranes. The particles themselves are large hydrophobic anions that have the ability to disperse in aqueous media and to partition over both sides of a phospholipid bilayer membrane. Their presence therefore causes a membrane potential that is determined by the relative concentrations of particles on each side of the membrane according to the Nernst equation. The particles tend to adsorb to both sides of the membrane and can flip across if changes in membrane potential require their repartitioning. Such changes can be made either with …


On The Temporal Effects Of Mobile Blockers In Urban Millimeter-Wave Cellular Scenarios, Margarita Gapeyenko, Mikhail Gerasimenko, Andrey Samuylov, Dmitri Moltchanov, Sarabjot Singh, Mustafa Riza Akdeniz, Ehsan Aryafar, Nageen Himayat, Sergey Andreev, Yevgeni Koucheryavy Nov 2017

On The Temporal Effects Of Mobile Blockers In Urban Millimeter-Wave Cellular Scenarios, Margarita Gapeyenko, Mikhail Gerasimenko, Andrey Samuylov, Dmitri Moltchanov, Sarabjot Singh, Mustafa Riza Akdeniz, Ehsan Aryafar, Nageen Himayat, Sergey Andreev, Yevgeni Koucheryavy

Computer Science Faculty Publications and Presentations

Millimeter-wave (mmWave) propagation is known to be severely affected by the blockage of the line-of-sight (LoS) path. In contrast to microwave systems, at shorter mmWave wavelengths such blockage can be caused by human bodies, where their mobility within environment makes wireless channel alternate between the blocked and non-blocked LoS states. Following the recent 3GPP requirements on modeling the dynamic blockage as well as the temporal consistency of the channel at mmWave frequencies, in this paper a new model for predicting the state of a user in the presence of mobile blockers for representative 3GPP scenarios is developed: urban micro cell …


An Analysis Of The Optimal Mix Of Global Energy Resources And The Potential Need For Geoengineering Using The Ceagom Model, John George Anasis, M. A. K. Khalil, George G. Lendaris, Christopher L. Butenhoff, Randall Bluffstone Oct 2017

An Analysis Of The Optimal Mix Of Global Energy Resources And The Potential Need For Geoengineering Using The Ceagom Model, John George Anasis, M. A. K. Khalil, George G. Lendaris, Christopher L. Butenhoff, Randall Bluffstone

Systems Science Faculty Publications and Presentations

Humanity faces tremendous challenges as a result of anthropogenic climate change caused by greenhouse gas emissions. The mix of resources deployed in order to meet the energy needs of a growing global population is key to addressing the climate change issue. The goal of this research is to examine the optimal mix of energy resources that should be deployed to meet a forecast global energy demand while still meeting desired climate targets. The research includes the unique feature of examining the role that geoengineering can play in this optimization. The results show that some form of geoengineering is likely to …


Data Envelopment Analysis Using Glpkapi In R, Konrad Miziolek, Jordan Beary, Shreyas Vasanth, Surekha Chanamolu, Rudraxi Mitra Oct 2017

Data Envelopment Analysis Using Glpkapi In R, Konrad Miziolek, Jordan Beary, Shreyas Vasanth, Surekha Chanamolu, Rudraxi Mitra

Engineering and Technology Management Student Projects

The work done here is primarily a wrapper function written to separate some of the more difficult-to-use glpkAPI functionality from the end-user. The user, when prompted, selects the appropriate configuration of the .mod file to the task (for example, output-oriented CRS), and the data file, as a .dat. The function then loads the required glpkAPI library, and carries forward the model. It allocates the problem and workspace, reads the model file and data file the user selects, builds the problem, and solves it. The function returns primal values, and, if dual = TRUE is selected, also returns dual weights.


Forest Collaborative Meeting Agenda, Addis Ababa, Ethiopia, Environment For Development (Efd) Initiative Oct 2017

Forest Collaborative Meeting Agenda, Addis Ababa, Ethiopia, Environment For Development (Efd) Initiative

Forest Collaborative Research

Agenda for the Environment for Development (EfD) Initiative Annual Meeting on 27-30 October 2017 at Capital Hotel, Addis Ababa, Ethiopia.


Formalizing The Panarchy Adaptive Cycle With The Cusp Catastrophe, Martin Zwick, Joshua Hughes Oct 2017

Formalizing The Panarchy Adaptive Cycle With The Cusp Catastrophe, Martin Zwick, Joshua Hughes

Systems Science Faculty Publications and Presentations

The panarchy adaptive cycle, a general model for change in natural and human systems, can be formalized by the cusp catastrophe of René Thom's topological theory. Both the adaptive cycle and the cusp catastrophe have been used to model ecological, economic, and social systems in which slow and small continuous changes in two control variables produce fast and large discontinuous changes in system behavior. The panarchy adaptive cycle, the more recent of the two models, has been used so far only for qualitative descriptions of typical dynamics of such systems. The cusp catastrophe, while also often employed qualitatively, is a …


Ideas & Graphs, Martin Zwick Oct 2017

Ideas & Graphs, Martin Zwick

Systems Science Faculty Publications and Presentations

A graph can specify the skeletal structure of an idea, onto which meaning can be added by interpreting the structure.

This paper considers graphs (but not hypergraphs) consisting of four nodes, and suggests meanings that can be associated with several different directed and undirected graphs.

Drawing on Bennett's "systematics," specifically on the Tetrad that systematics offers as a model of 'activity,' the analysis here shows that the Tetrad is versatile model of problem-solving, regulation and control, and other processes.


Finding Water Scarcity Amid Abundance Using Human–Natural System Models, William K. Jaeger, Adell Amos, Daniel P. Bigelow, Heejun Chang, David R. Conklin, Roy Haggerty, Christian Langpap, Kathleen Moore, Philip Mote, Anne W. Nolin, Andrew J. Plantinga, Cynthia L. Schwartz, Desiree Tullos, David P. Turner Oct 2017

Finding Water Scarcity Amid Abundance Using Human–Natural System Models, William K. Jaeger, Adell Amos, Daniel P. Bigelow, Heejun Chang, David R. Conklin, Roy Haggerty, Christian Langpap, Kathleen Moore, Philip Mote, Anne W. Nolin, Andrew J. Plantinga, Cynthia L. Schwartz, Desiree Tullos, David P. Turner

Geography Faculty Publications and Presentations

Water scarcity afflicts societies worldwide. Anticipating water shortages is vital because of water’s indispensable role in social-ecological systems. But the challenge is daunting due to heterogeneity, feedbacks, and water’s spatial-temporal sequencing throughout such systems. Regional system models with sufficient detail can help address this challenge. In our study, a detailed coupled human–natural system model of one such region identifies how climate change and socioeconomic growth will alter the availability and use of water in coming decades. Results demonstrate how water scarcity varies greatly across small distances and brief time periods, even in basins where water may be relatively abundant overall. …


Quantifying Resilience Of Multiple Ecosystem Services And Biodiversity In A Temperate Forest Landscape, Elena Cantarello, Adrian C. Newton, Phillip A. Martin, Paul M. Evans, Arjan Gosal, Melissa S. Lucash Oct 2017

Quantifying Resilience Of Multiple Ecosystem Services And Biodiversity In A Temperate Forest Landscape, Elena Cantarello, Adrian C. Newton, Phillip A. Martin, Paul M. Evans, Arjan Gosal, Melissa S. Lucash

Geography Faculty Publications and Presentations

Resilience is increasingly being considered as a new paradigm of forest management among scientists, practitioners, and policymakers. However, metrics of resilience to environmental change are lacking. Faced with novel disturbances, forests may be able to sustain existing ecosystem services and biodiversity by exhibiting resilience, or alternatively these attributes may undergo either a linear or nonlinear decline. Here we provide a novel quantitative approach for assessing forest resilience that focuses on three components of resilience, namely resistance, recovery, and net change, using a spatially explicit model of forest dynamics. Under the pulse set scenarios, we explored the resilience of nine ecosystem …


Random Walks On Digraphs, J.J.P. Veerman Oct 2017

Random Walks On Digraphs, J.J.P. Veerman

Mathematics and Statistics Faculty Publications and Presentations

Let V = {1, · · · n} be a vertex set and S a non-negative row-stochastic matrix (i.e. rows sum to 1). V and S define a digraph G = G(V, S) and a directed graph Laplacian L as follows. If (S)ij > 0 (in what follows we will leave out the parentheses) there is a directed edge j → i. Thus the ith row of S identifies the edges coming into vertex i and their weights. This set of vertices are collectively the neighbors of i, and is denoted by Ni . The diagonal elements Sii are chosen such …


Formalizing The Panarchy Adaptive Cycle With The Cusp Catastrophe [Presentation], Martin Zwick, Joshua Hughes Oct 2017

Formalizing The Panarchy Adaptive Cycle With The Cusp Catastrophe [Presentation], Martin Zwick, Joshua Hughes

Systems Science Faculty Publications and Presentations

The panarchy adaptive cycle, a general model for change in natural and human systems, can be formalized by the cusp catastrophe of René Thom's topological theory. Both the adaptive cycle and the cusp catastrophe have been used to model ecological, economic, and social systems in which slow and small continuous changes in two control variables produce fast and large discontinuous changes in system behavior. The panarchy adaptive cycle, the more recent of the two models, has been used so far only for qualitative descriptions of typical dynamics of such systems. The cusp catastrophe, while also often employed qualitatively, is a …


Values Mapping And Counter-Mapping In Contested Landscapes: An Olympic Peninsula (Usa) Case Study, Rebecca J. Mclain, Lee Cerveny, Kelly Biedenweg, David Banis Oct 2017

Values Mapping And Counter-Mapping In Contested Landscapes: An Olympic Peninsula (Usa) Case Study, Rebecca J. Mclain, Lee Cerveny, Kelly Biedenweg, David Banis

Geography Faculty Publications and Presentations

Indigenous peoples, local communities, and other groups can use counter-mapping to make land claims, identify areas of desired access, or convey cultural values that diverge from the dominant paradigm. While sometimes created independently, counter-maps also can be formulated during public participation mapping events sponsored by natural resource planning agencies. Public participation mapping elicits values, uses, and meanings of landscapes from diverse stakeholders, yet individuals and advocacy groups can use the mapping process as an opportunity to make visible strongly held values and viewpoints. We present three cases from the Olympic Peninsula in Washington State to illustrate how stakeholders intentionally used …


A Comparative Assessment Of Projected Meteorological And Hydrological Droughts: Elucidating The Role Of Temperature, Ali Ahmadalipour, Hamid Moradkhani, Mehmet C. Demirel Oct 2017

A Comparative Assessment Of Projected Meteorological And Hydrological Droughts: Elucidating The Role Of Temperature, Ali Ahmadalipour, Hamid Moradkhani, Mehmet C. Demirel

Civil and Environmental Engineering Faculty Publications and Presentations

The changing climate and the associated future increases in temperature are expected to have impacts on drought characteristics and hydrologic cycle. This paper investigates the projected changes in spatiotemporal characteristics of droughts and their future attributes over the Willamette River Basin (WRB) in the Pacific Northwest U.S. The analysis is performed using two subsets of downscaled CMIP5 global climate models (GCMs) each consisting of 10 models from two future scenarios (RCP4.5 and RCP8.5) for 30 years of historical period (1970–1999) and 90 years of future projections (2010–2099). Hydrologic modeling is conducted using the Precipitation Runoff Modeling System (PRMS) as a …


The Influence Of Recurrent Modes Of Climate Variability On The Occurrence Of Monthly Temperature Extremes Over South America, Paul C. Loikith, Judah Detzer, Carlos R. Mechoso, Huikyo Lee, Armineh Barkhordarian Sep 2017

The Influence Of Recurrent Modes Of Climate Variability On The Occurrence Of Monthly Temperature Extremes Over South America, Paul C. Loikith, Judah Detzer, Carlos R. Mechoso, Huikyo Lee, Armineh Barkhordarian

Geography Faculty Publications and Presentations

The associations between extreme temperature months and four prominent modes of recurrent climate variability are examined over South America. Associations are computed as the percent of extreme temperature months concurrent with the upper and lower quartiles of the El Niño–Southern Oscillation (ENSO), the Atlantic Niño, the Pacific Decadal Oscillation (PDO), and the Southern Annular Mode (SAM) index distributions, stratified by season. The relationship is strongest for ENSO, with nearly every extreme temperature month concurrent with the upper or lower quartiles of its distribution in portions of northwestern South America during some seasons. The likelihood of extreme warm temperatures is enhanced …


Toxicant Formation In Dabbing: The Terpene Story, Jiries Meehan-Attrash, Wentai Luo, Robert M. Strongin Sep 2017

Toxicant Formation In Dabbing: The Terpene Story, Jiries Meehan-Attrash, Wentai Luo, Robert M. Strongin

Chemistry Faculty Publications and Presentations

Inhalable, noncombustible cannabis products are playing a central role in the expansion of the medical and recreational use of cannabis. In particular, the practice of “dabbing” with butane hash oil has emerged with great popularity in states that have legalized cannabis. Despite their growing popularity, the degradation product profiles of these new products have not been extensively investigated. The study herein focuses on the chemistry of myrcene and other common terpenes found in cannabis extracts. Methacrolein, benzene, and several other products of concern to human health were formed under the conditions that simulated realworld dabbing. The terpene degradation products observed …


Filtered Subspace Iteration For Selfadjoint Operators, Jay Gopalakrishnan, Luka Grubišić, Jeffrey S. Ovall Sep 2017

Filtered Subspace Iteration For Selfadjoint Operators, Jay Gopalakrishnan, Luka Grubišić, Jeffrey S. Ovall

Portland Institute for Computational Science Publications

We consider the problem of computing a cluster of eigenvalues (and its associated eigenspace) of a (possibly unbounded) selfadjoint operator in a Hilbert space. A rational function of the operator is constructed such that the eigenspace of interest is its dominant eigenspace, and a subspace iteration procedure is used to approximate this eigenspace. The computed space is then used to obtain approximations of the eigenvalues of interest. An eigenvalue and eigenspace convergence analysis that considers both iteration error and dis- cretization error is provided. A realization of the proposed approach for a model second-order elliptic operator is based on a …


Southern Annular Mode Drives Multicentury Wildfire Activity In Southern South America, Andrés Holz, Juan Paritsis, Ignacio A. Mundo, Thomas T. Veblen, Thomas Kitzberger, Grant J. Williamson, Ezequiel Aráoz, Carlos Bustos-Schindler, Mauro E. González, H. Ricardo Grau, Juan M. Quezada Sep 2017

Southern Annular Mode Drives Multicentury Wildfire Activity In Southern South America, Andrés Holz, Juan Paritsis, Ignacio A. Mundo, Thomas T. Veblen, Thomas Kitzberger, Grant J. Williamson, Ezequiel Aráoz, Carlos Bustos-Schindler, Mauro E. González, H. Ricardo Grau, Juan M. Quezada

Geography Faculty Publications and Presentations

The Southern Annular Mode (SAM) is the main driver of climate variability at mid to high latitudes in the Southern Hemisphere, affecting wildfire activity, which in turn pollutes the air and contributes to human health problems and mortality, and potentially provides strong feedback to the climate system through emissions and land cover changes. Here we report the largest Southern Hemisphere network of annually resolved tree ring fire histories, consisting of 1,767 fire-scarred trees from 97 sites (from 22 °S to 54 °S) in southern South America (SAS), to quantify the coupling of SAM and regional wildfire variability using recently created …