Physics Commons^™

The Role Of Volatile Enrichment In The Radiogenic Heating And Thermal Evolution Of Rocky Exoplanets, Ula Jones, Asmaa Boujibar

WWU Honors College Senior Projects

Internal heating in terrestrial planets is a fundamental physical process controlling the internal structure of a planet, mantle convection, volcanic activity, and the generation of magnetic fields. Internal heating results from various processes including radioactive decay and accretional energy, as well as additional irradiation and tidal heating in planets with short orbital periods. The largest long-term heat source for terrestrial planets is radioactive heating, especially from the decay of uranium (U), thorium (Th), and potassium (K) isotopes. K is a moderately volatile element, while U and Th are refractory elements; during planetary accretion volatiles are depleted relative to refractory elements, …

Physical Properties Of Brackett Emitters In The Apogee Dr17 Catalog, Elliott Khilfeh, Hunter Campbell, Kevin R. Covey, Marina Kounkel, Richard Ballentyne

WWU Honors College Senior Projects

In the process of accumulating mass (accretion), young stars channel ionized gas from the protoplanetary disk to the stellar surface along magnetic field lines. Upon impacting the photosphere, the gas cools down, recombining and emitting hydrogen spectral lines. Measuring these emission lines allows us to determine the temperature and density of the gas in those accretion streams. This then enables us to test whether those parameters depend on the accretion rate. We present measurements of equivalent widths and line ratios for Brackett (Br) 11 – 20 lines for 3366 observations of 940 pre-main sequence stars observed with APOGEE as of …

Can Women Science?: A Climate Survey To Address Gender Inequity In Wwu’S Geology And Physics/Astronomy Departments, Raina Shaw

WWU Honors College Senior Projects

This research study aims to assess and analyze gendered differences in student perceptions of the environment and climate in WWU’s Geology and Physics & Astronomy Departments. Underlying hypotheses involve the perceptions, comfort, and discrimination of women and gender minorities in male-dominated spaces. We also theorize that these gendered differences will increase with seniority and more so within physics than in geology. In addition to testing these hypotheses, we sought to collect relevant student feedback on factors that influence their perceptions of the climate & environment, to identify areas for future study and formal program assessment. From 56 respondents, this study …

Cross-Disciplinary Learning Index: A Quantitative Measure Of Cross-Disciplinary Learning About Energy, Todd Haskell, Emily Borda, Andrew Boudreaux

Physics & Astronomy

The structure of many science programs at the college level assumes that students are able to draw on and integrate ideas from multiple disciplinary contexts. However, most assessment tools focus on learning in the context of a single discipline. We describe the development and validation of an instrument to measure how well students are able to combine energy ideas from different disciplines into a coherent understanding of a phenomenon. The final version of the instrument consists of a pair of multiple-choice online assessments, along with a metric calculated from the assessment scores: the cross disciplinary learning index (CDLI). The items …

Physics Inventory Of Quantitative Literacy: A Tool For Assessing Mathematical Reasoning In Introductory Physics, Suzanne W. Brahmia, Alexis Olsho, Trevor I. Smith, Andrew Boudreaux, Philip Eaton, Charlotte Zimmerman

Physics & Astronomy

One desired outcome of introductory physics instruction is that students will develop facility with reasoning quantitatively about physical phenomena. Little research has been done regarding how students develop the algebraic concepts and skills involved in reasoning productively about physics quantities, which is different from either understanding of physics concepts or problem-solving abilities. We introduce the Physics Inventory of Quantitative Literacy (PIQL) as a tool for measuring Quantitative Literacy, a foundation of mathematical reasoning, in the context of introductory physics. We present the development of the PIQL and evidence of its validity for use in calculus-based introductory physics courses. Unlike …

How Curriculum Developers Cognitive Theories Influence Curriculum Development, Andrew Boudreaux, Andy Elby

Physics & Astronomy

[This paper is part of the Focused Collection on Curriculum Development: Theory into Design.] When we examined student responses to questions about the direction of the static friction force in various situations, we both had strong ideas about how to write a tutorial to promote deeper understanding. But our ideas were quite different. In this theoretical paper, we present the two contrasting tutorials and show how their differences can be traced to different theoretical orientations toward cognition and learning. We do not claim that one tutorial—or the theoretical framework loosely associated with it—is superior. Instead, we hope to illustrate two …

Designing Research-Based Instructional Materials That Leverage Dual-Process Theories Of Reasoning: Insights From Testing One Specific, Theory-Driven Intervention, Mila Kryjevskaia, Mackenzie R. Stetzer, Beth A. Lindsey, Alistair Mcinerny, Paula R. L. Heron, Andrew Boudreaux

Physics & Astronomy

[This paper is part of the Focused Collection on Curriculum Development: Theory into Design.] Research in physics education has contributed substantively to improvements in the learning and teaching of university physics by informing the development of research-based instructional materials for physics courses. Reports on the design of these materials have tended to focus on overall improvements in student performance, while the role of theory in informing the development, refinement, and assessment of the materials is often not clearly articulated. In this article, we illustrate how dual-process theories of reasoning and decision making have guided the ongoing development, testing, and analysis …

The Political Economy Of Nuclear Energy: Why There Is Not Broad Public Support For Nuclear Policy & Why There Should Be, Willa Grace Mei Lee

WWU Honors College Senior Projects

In this paper, I examine how the nuclear incidents at Three Mile Island, Chernobyl, and Fukushima impacted public support for nuclear energy in the United States. Particularly, I look at the ways the media has influenced public perception, and thus, nuclear policy. I also consider the economic arguments for and against using nuclear power and highlight the effects of decommissioning nuclear fleets as was seen in the aftermath of the major nuclear incidents. Lastly, I discuss how the public can become better informed on nuclear energy.

Ultimately, the three major nuclear incidents spurred anti-nuclear sentiment, which shut down nuclear plants, …

Toward A Framework For The Natures Of Proportional Reasoning In Introductory Physics, Andrew Boudreaux, Stephen E. Kanim, Alexis Olsho, Suzanne W. Brahmia, Charlotte Zimmerman, Trevor I. Smith

Physics & Astronomy

We present a set of modes of reasoning about ratio and proportion as a means of operationalizing expert practice in physics. These modes, or natures of proportional reasoning, stem from consideration of how physicists reason in context and are informed by prior work in physics and mathematics education. We frame the natures as the core of an emerging framework for proportional reasoning in introductory physics, that will categorize the uses of proportional reasoning in introductory physics contexts, and provide guidance for the development of reliable assessments. We share results from preliminary assessment items indicating that university physics students have difficulty …

Framework For The Natures Of Negativity In Introductory Physics, Suzanne W. Brahmia, Alexis Olsho, Trevor I. Smith, Andrew Boudreaux

Physics & Astronomy

Mathematical reasoning skills are a desired outcome of many introductory physics courses, particularly calculus-based physics courses. Novices can struggle to understand the many roles signed numbers play in physics contexts, and recent evidence shows that unresolved struggle can carry over to subsequent physics courses. Positive and negative quantities are ubiquitous in physics, and the sign carries important and varied meanings. The mathematics education research literature documents the cognitive challenge of conceptualizing negative numbers as mathematical objects—both for experts, historically, and for novices as they learn. We contribute to the small but growing body of research in physics contexts that examines …

Effects Of Contact Interactions In Molecular Bose-Einstein Condensates, Devin Crowley, Ryan M. Wilson, Seth Rittenhouse, Brandon M. Peden

WWU Honors College Senior Projects

We investigate the ground state and low-lying excitations of a Bose-Einstein condensate (BEC) of dipolar molecules interacting via short-range contact and long-range dipole­ dipole interactions (ddi). We find the mean field ground state via the variational principle using a separable bosonic wave function as the variational state. This state can be refined to include small excitations in the form of plane waves, and the results of the variational calculation are a set of dispersion relations for the low-lying excitations. We analyze the polarization and stability of the ground state as a function of the strength of the external polarizing electric …

Structural And Antiferromagnetic Properties Of Ba(Fe1−X−Ycoxrhy)2as2 Compounds, M. G. Kim, T. W. Heitmann, Sean R. Mulcahy, E. D. Bourret-Courchesne, R. J. Birgeneau

Geology Faculty Publications

We present a systematic investigation of the electrical, structural, and antiferromagnetic properties for the series of Ba(Fe_{1 −x−y}Co_xRh_y)₂As₂ compounds with fixed x ≈ 0.027 and 0 ≤ y ≤ 0.035. We compare our results for the Co-Rh doped Ba(Fe_1−x−yCo_xRh_y)₂As₂ compounds with the Co doped Ba(Fe_1−xCo_x)₂As₂ compounds. We demonstrate that the electrical, structural, antiferromagnetic, and superconducting properties of the Co-Rh doped compounds are similar to the properties of the Co doped compounds. We find that the …

How Accurate Are Physics Students In Evaluating Changes In Their Understanding?, Therese Claire, Tija L. Tippett, Andrew Boudreaux

Physics & Astronomy

An assessment question involving Newton’s 2nd law was administered in a physics course for preservice elementary teachers before and again after instruction. The posttest included a prompt asking students to describe the specific ways their thinking changed. Student reasoning was coded for physics content accuracy; many students exhibited changes from primitive, experientially-based reasoning to more formal reasoning. Students' self-reported reflections were then compared to the differences in the pre- and posttest codes. We find that many students do not identify substantive changes in their reasoning, while other students reflect at only a surface level. We also find that some students …

Assessing The Flexibility Of Research-Based Instructional Strategies: Implementing Tutorials In Introductory Physics In The Lecture Environment, Mila Kryjevskaia, Andrew Boudreaux, Dustin Heins

Physics & Astronomy

Materials from Tutorials in Introductory Physics, originally designed and implemented by the Physics Education Group at the University of Washington, were used in modified form as interactive lectures under conditions significantly different from those suggested by the curriculum developers. Student learning was assessed using tasks drawn from the physics education research literature. Use of tutorials in the interactive lecture format yielded gains in student understanding comparable to those obtained through the canonical tutorial implementation at the University of Washington, suggesting that student engagement with the intellectual steps laid out in the tutorials, rather than the specific strategies used in …

Promoting And Assessing Student Metacognition In Physics, Alistair Mcinerny, Andrew Boudreaux, Mila Kryjevskaia, Sara Julin

Physics & Astronomy

A scaffolded metacognition activity was incorporated into the laboratory component of the introductory physics course at Western Washington University (WWU) and Whatcom Community College (WCC). Each week, students wrote reflectively to contrast their initial and current understanding of a specific physics topic, and described the "trigger" events that led them to change their thinking. Goals were to enhance conceptual understanding as well as the depth and quality of student reflection. A coding scheme was developed to evaluate student reflections. We present the scaffolded activity and coding scheme, as well as preliminary findings about changes in student reflection over time and …

Preliminary Investigation Of Instructor Effects On Gender Gap In Introductory Physics, Andrew Boudreaux, Kimberley Kreutzer

Physics & Astronomy

Gender differences in student learning in the introductory, calculus-based electricity and magnetism course were assessed by administering the Conceptual Survey of Electricity and Magnetism pre- and postcourse. As expected, male students outgained females in traditionally taught sections as well as sections that incorporated interactive engagement (IE) techniques. In two of the IE course sections, however, the gains of female students were comparable to those of male students. Classroom observations of the course sections involved were made over an extended period. In this paper, we characterize the observed instructor-student interactions using a framework from educational psychology referred to as wise schooling. …

Chemical Structure Of Vanadium-Based Contact Formation On N-Ain, S. Pookpanratana, R. France, M. Blum, Sean R. Mulcahy, A. Bell, M. Bär, L. Weinhardt, Y. Zhang, T. Hofmann, O. Fuchs, W. Yang, J. D. Denlinger, T. D. Moustakas, C. Heske

Geology Faculty Publications

We have investigated the chemical interaction between a Au/V/Al/V layer structure and n-type AlN epilayers using soft x-ray photoemission, x-ray emission spectroscopy, and atomic force microscopy. To understand the complex processes involved in this multicomponent system, we have studied the interface before and after a rapid thermal annealing step. We find the formation of a number of chemical phases at the interface, including VN, metallic vanadium, aluminum oxide, and metallic gold. An interaction mechanism for metal contact formation on the entire n-Al,GaN system is proposed. ©

Molecular Nanoscience And Engineering On Surfaces, Willi Auwarter, Agustin Schiffrin, Alexander Weber-Bargioni, Yan Pennec, Andreas Riemann, Johannes V. Barth

Physics & Astronomy

Molecular engineering of low-dimensional materials exploiting controlled self-assembly and positioning of individual atoms or molecules at surfaces opens up new pathways to control matter at the nanoscale. Our research thus focuses on the study of functional molecules and supramolecular architectures on metal substrates. As principal experimental tools we employ low-temperature scanning tunneling microscopy and spectroscopy. Here we review recent studies in our lab at UBC: Controlled manipulation of single CO molecules, self-assembled biomolecular nanogratings on Ag(111) and their use for electron confinement, as well as the organisation, conformation, metalation and electronic structure of adsorbed porphyrins.

Student Understanding Of Control Of Variables: Deciding Whether Or Not A Variable Influences The Behavior Of A System, Andrew Boudreaux, Peter S. Shaffer, Paula R. L. Heron, Lillian C. Mcdermott

Physics & Astronomy

The ability of adult students to reason on the basis of the control of variables was the subject of an extended investigation. This paper describes the part of the study that focused on the reasoning required to decide whether or not a given variable influences the behavior of a system. The participants were undergraduates taking introductory Physics and K-8 teachers studying physics and physical science in inservice institutes and workshops. Although most of the students recognized the need to control variables, many had significant difficulty with the underlying reasoning. The results indicate serious shortcomings in the preparation of future scientists …

Zwitterionic Self-Assembly Of L-Methionine Nanogratings On The Ag(111) Surface, Andreas Riemann, Agustin Schiffrin, Willi Auwarter, Yan Pennec, Alex Weber-Bargioni, Albano Cossaro, Alberto Morgante, Johannes V. Barth

Physics & Astronomy

The engineering of complex architectures from functional molecules on surfaces provides new pathways to control matter at the nanoscale. In this article, we present a combined study addressing the self-assembly of the amino acid L-methionine on Ag(111). Scanning tunneling microscopy data reveal spontaneous ordering in extended molecular chains oriented along high-symmetry substrate directions. At intermediate coverages, regular biomolecular gratings evolve whose periodicity can be tuned at the nanometer scale by varying the methionine surface concentration. Their characteristics and stability were confirmed by helium atomic scattering. X-ray photoemission spectroscopy and high-resolution scanning tunneling microscopy data reveal that the L-methionine chaining is …

A Dft Study Of Iron-Oxide Nanoparticle Ground-State Geometries, Danielle Mcdermott

WWU Honors College Senior Projects

Density Functional Theory was used to construct a ground state configuration for Fe203, or maghemite. The bipyramidal structure that resulted from a numerical optimization scheme was computationally stable with a lower energy than individual (free) components of the molecule. These stable bipyramids form a basic building block to generate iron-oxide nanoparticles. The primary focus of the study is understanding appropriate input geometries and using proper basis sets to model the real system, and to approximate possible reaction kinetics with other compounds.

Characterization Of Sputtered Fe Thin Films, Cedar S. Wolf

WWU Honors College Senior Projects

The temperature dependence of the electrical resistance for Fe films with thicknesses of 20-400 nm has been investigated. The films were prepared by DC magnetron sputtering onto SiO2 substrates. The investigation was prompted by the purchase of new lab equipment by Western Washington University and the necessity to test their basic functionality. The film thicknesses were characterized by x-ray diffraction for films up to about 200 nm. Temperature effects were observed by using a closed-cycle refrigerator. An anomalous dip in resistance was detected around 40-50 K for all samples. The resistivity of these films was also calculated and compared to …

Self-Assembly And Conformation Of Tetrapyridilporphyrin On The Ag(111) Surface, Willi Auwärter, Alexander Weber-Bargioni, Andreas Riemann, Agustin Schiffrin, R. Fasel, O. Gröning, Johannes V. Barth

Physics & Astronomy

We present a low-temperature scanning tunneling microscopy (STM) study on the supramolecular ordering of tetrapyridyl-porphyrin (TPyP) molecules on Ag(111). Vapor deposition in a wide substrate temperature range reveals that TPyP molecules easily diffuse and self-assemble into large, highly ordered chiral domains. We identify two mirror-symmetric unit cells, each containing two differently oriented molecules. From an analysis of the respective arrangement it is concluded that lateral intermolecular interactions control the packing of the layer, while its orientation is induced by the coupling to the substrate. This finding is corroborated by molecular mechanics calculations. High-resolution STM images recorded at 15 K allow …

Electrical Transport, Magnetism, And Spin-State Configurations Of High-Pressure Phases Of Fes, Takele Seda, G. R. Hearne

Physics & Astronomy

Both the nature of the electrical transport and magnetism of high-pressure phases of FeS have been elucidated in relation to the spin-state configuration of Fe. This has been achieved by combined ⁵⁷FeMössbauer spectroscopy and resistance measurements on samples pressurized in miniature gem-anvil pressure cells to ∼12 GPa in the range 300–5 K. Hexagonal FeS in the range 3–7 GPa exhibits magnetic nonmetallic behavior, whereas monoclinic FeS beyond ∼7 GPa is diamagnetic and nonmetallic. This is compelling experimental evidence to show that, along the room-temperature isotherm, hexagonal FeS has thermally activated charge carriers and a high-spin magnetic-electronic configuration, whereas monoclinic …

An Electroabsorption Study Of Porous Silicon, Melanie Fewings

WWU Honors College Senior Projects

Bulk silicon is an indirect band gap material. When carriers are injected into bulk silicon, electron-hole recombination takes place thermally via phonon exchange, and not by emission of photons. Porous silicon, on the other hand, is a fairly efficient emitter of light in the visible region. Much research is currently under way to find out what makes porous silicon able to emit light. One main theory suggests that the energy bands of bulk silicon may be "squeezed" by being quantum confined, and porous silicon is just an array of quantum silicon wires. Another possibility is that defects in the huge …

Local Magnetic Properties Of Antiferromagnetic Febr2, J. Peloth, R. A. Brand, Takele Seda, M. M. Pereira De Azevedo, W. Kleeman, Ch. Binek, J. Kushauer, D. Bertrand

Physics & Astronomy

The antiferromagnet FeBr₂ has been studied by Mössbauer spectroscopy in external fields both in the metamagnetic region below the multicritical temperature T_MCP and in the second-order transition region above. The local magnetization shows that the metamagnetic transition occurs by spin flips, as in simple models. However, in the second-order transition region, the local magnetization of the sublattice oriented antiparallel to the external field varies continuously but remains parallel to the c axis. This can only be understood if the external magnetic field induces strong transversal spin precession of the moments on the antiparallel sublattice. This shows that the …