New Methodologies for Examining and Supporting Student Reasoning in Physics

Learning how to reason productively is an essential goal of an undergraduate education in any STEM-related discipline. Many non-physics STEM majors are required to take introductory physics as part of their undergraduate programs. While certain physics concepts and principles may be of use to these students in their future academic careers and beyond, many will not. Rather, it is often expected that the most valuable and longlasting learning outcomes from a physics course will be a repertoire of problem-solving strategies, a familiarity with mathematizing real-world situations, and the development of a strong set of qualitative inferential reasoning skills. For more than 40 years, the physics education research community has produced many research-based instructional materials that have been shown to improve student conceptual understanding and other targeted learning outcomes (e.g., problem solving). It is often tacitly assumed that such materials also improve students’ qualitative reasoning skills, but there is no documented evidence of this, to date, in the literature. Furthermore, a growing body of research has revealed that a focus on conceptual understanding does not always result in the anticipated performance outcomes. Indeed, students may demonstrate solid conceptual understanding on one physics question but fail to demonstrate that same understanding on a closely related question. This body of research suggests that reasoning processes general to all humans (i.e., domain-general processes) may impact how students understand and reason with physics concepts. Methodologies that separate (to the degree possible) the reasoning involved in a physics problem from the conceptual understanding necessary to correctly answer that problem are necessary for gaining insight into how conceptual understanding and domain-general reasoning processes interact. In order to explore such research questions, new research tools and analysis methodologies are required. Physics education researchers pursuing these questions have begun to embrace data-collection methodologies outside of the written free-response questions and think-aloud interviews that are ubiquitous in discipline-based education research. Some of these researchers have also begun to utilize dual-process theories of reasoning (DPToR) as an analysis framework. Dual-process theories arise from findings in cognitive science, social psychology, and the psychology of reasoning. These theories tend to be mechanistic in nature; as such, they provide a framework that can be prescriptive rather than solely descriptive, thereby providing a theoretical basis for examining the interplay of domain-general and domain-specific reasoning. In the work described in this thesis, we sought to gain greater insight into the nature of student reasoning in physics and the extent to which it is impacted by the domain-general phenomena explored by cognitive science. This was accomplished by developing and implementing new methodologies to examine qualitative inferential reasoning that separate reasoning skills from understanding of a particular physics concept. In this work we present two such methodologies: reasoning chain construction tasks, in which students are provided with correct reasoning elements (i.e., true statements about the physical situation as well as correct concepts and mathematical relationships) and are asked to assemble them into an argument in order to answer a physics question; and possibility exploration tasks, which are designed to measure student ability to consider multiple possibilities when answering a physics problem. The overarching goal of these novel tasks is to explore mechanistic processes related to the generation of qualitative inferential reasoning chains and to uncover insight into the nature of student reasoning more generally. The work reported in this dissertation has yielded a variety of important results. In concert with reasoning-chain construction tasks, the dual-process framework has been leveraged to provide testable hypotheses about student reasoning and to inform the design of an instructional intervention to support student reasoning. By applying network analysis approaches to data produced by reasoning chain construction tasks with network analysis, insights were uncovered regarding the structure of student reasoning in different contexts, and the development of a coherent reasoning structure over the course of a two-semester physics course was documented. Finally, students’ tendency to explore possibilities has been, both in the literature and in this dissertation, found to impact performance on physics questions. This tendency is examined and a possible mechanism controlling this tendency has been proposed. Taken together, these investigations and findings constitute substantive advances in how student reasoning is studied and serve to open new doors for future research

Uncertainty in the availability of natural resources: Fossil fuels, critical metals and biomass

Energy policies are strongly influenced by resource availability and recoverability estimates. Yet these estimates are often highly uncertain, frequently incommensurable, and regularly contested. This paper explores how the uncertainties surrounding estimates of the availability of fossil fuels, biomass and critical metals are conceptualised and communicated. The contention is that a better understanding of the uncertainties surrounding resource estimates for both conventional and renewable energy resources can contribute to more effective policy decision making in the long term. Two complementary approaches for framing uncertainty are considered in detail: a descriptive typology of uncertainties and a framework that conceptualises uncertainty as alternative states of incomplete knowledge. Both have the potential to be useful analytical and communication tools. For the three resource types considered here we find that data limitations, inconsistent definitions and the use of incommensurable methodologies present a pervasive problem that impedes comparison. Many aspects of resource uncertainty are also not commonly captured in the conventional resource classification schemes. This highlights the need for considerable care when developing and comparing aggregate resource estimates and when using these to inform strategic energy policy decisions

Investigating trends in the growth of five demersal fish species from the Firth of Clyde and the wider western shelf of Scotland

Demersal fish landings from the Firth of Clyde peaked in 1973, then declined rapidly until the targeted demersal fishery ceased in 2005. The abundance of large fish decreased during this period, and their numbers have not recovered since 2005. We aim to determine whether changing growth rates have con- tributed to the decline in the abundance of large fish. Bottom trawl survey data from 1980–2012 was used to calculate the annual mean length-at-age and time series of von Bertalanffy growth parameters of five demersal species; cod, haddock, whiting, Norway pout and saithe. Two regions were considered: the Firth of Clyde and the neighbouring seas west of Scotland (the western shelf). There have been substantial decreases in the lengths of most age groups of Clyde haddock and whiting due to declines in both asymptotic length and von Bertalanffy growth rate. Lengths-at-age have also declined in western shelf populations, but at markedly slower rates than within the Clyde. Trends in temperature and year class strength tended to contribute little to changes in the growth parameters, so declines in length-at-age have been largely due to other factors. Fishing intensity is greater in the Clyde than western shelf, and the size selectivity of the fisheries differ as more Clyde vessels use Nephrops trawling gear. Since trends in growth were also more extreme in the Clyde, it appears as though size-selective fishing may have caused reductions in the lengths of these fish. If the changes in growth are partially due to fishing induced evolution then it may take many generations for the changes to reverse

Electrostatic electron cyclotron instabilities near the upper hybrid layer due to electron ring distributions

A theoretical study is presented of the electrostatic electron cyclotron instability involving Bernstein modes in a magnetized plasma. The presence of a tenuous thermal ring distribution in a Maxwellian plasma decreases the frequency of the upper hybrid branch of the electron Bernstein mode until it merges with the nearest lower branch with a resulting instability. The instability occurs when the upper hybrid frequency is somewhat above the third, fourth, and higher electron cyclotron harmonics, and gives rise to a narrow spectrum of waves around the electron cyclotron harmonic nearest to the upper hybrid frequency. For a tenuous cold ring distribution together with a Maxwellian distribution an instability can take place also near the second electron cyclotron harmonic. Noise-free Vlasov simulations are used to assess the theoretical linear growth-rates and frequency spectra, and to study the nonlinear evolution of the instability. The relevance of the results to laboratory and ionospheric heating experiments is discussed

Characterisation of materials with hyperelastic microstructures through computational homogenisation and optimisation methods.

The constitutive modelling of microheterogeneous materials is a subject of considerable practical and theoretical interest. Among many approaches computational homogenisation is particularly powerful and versatile. This is based on the numerical estimation of the mechanical response of a volume element representing the material's microstructure. This thesis is concerned with computational homogenisation and its particular use in characterising materials with hyperelastic microstructures through an optimisation based methodology. Details of a finite element implementation of the computational homogenisation procedure are presented. These are derived from a variational treatment of the homogenisation problem. Examples of the application of the method to hyperelastic microstructures are reported. Next a procedure to provide a convenient characterisation of the behaviour of composite material is considered. This consists of adopting a conventional explicit model to approximate the macroscopic mechanical behaviour. Parameters of the model are chosen by established optimisation methods so that the macro model best fits the calculated homogenised response of a model of the microstructure. The optimisation based methodology is applied to the problem of modelling the constitutive behaviour of artery walls

Development of welding techniques and filler metals for high strength aluminum alloys Annual summary report, 27 Jun. 1964 - 27 Jun. 1965

Welding techniques and filler metals for high strength aluminum alloy

The effect of viral plasticity on the persistence of host-virus systems

Phenotypic plasticity plays an important role in the survival of individuals. In microbial host-virus systems, previous studies have shown the stabilizing effect that host plasticity has on the coexistence of the system. By contrast, it remains uncertain how the dependence of the virus on the metabolism of the host (i.e. “viral plasticity”) shapes bacteria-phage population dynamics in general, or the stability of the system in particular. Moreover, bacteria-phage models that do not consider viral plasticity are now recognised as overly simplistic. For these reasons, here we focus on the effect of viral plasticity on the stability of the system under different environmental conditions. We compared the predictions from a standard bacteria-phage model, which neglects plasticity, with those of a modification that includes viral plasticity. We investigated under which conditions viral plasticity promotes coexistence, with or without oscillatory dynamics. Our analysis shows that including viral plasticity reveals coexistence in regions of the parameter space where models without plasticity predict a collapse of the system. We also show that viral plasticity tends to reduce population oscillations, although this stabilizing effect is not consistently observed across environmental conditions: plasticity may instead reinforce dynamic feedbacks between the host, the virus, and the environment, which leads to wider oscillations. Our results contribute to a deeper understanding of the dynamic control of bacteriophage on host populations observed in nature

Projected impacts of 21st century climate change on diapause in Calanus finmarchicus

Diapause plays a key role in the life cycle of high latitude zooplankton. During diapause animals avoid starving in winter by living in deep waters where metabolism is lower and met by lipid reserves. Global warming is therefore expected to shorten the maximum potential diapause duration by increasing metabolic rates and by reducing body size and lipid reserves. This will alter the phenology of zooplankton, impact higher trophic levels and disrupt biological carbon pumps. Here we project the impacts of climate change on the key North Atlantic copepod Calanus finmarchicus under IPCC RCP 8.5. Potential diapause duration is modelled in relation to body size and overwintering temperature. The projections show pronounced geographic variations. Potential diapause duration reduces by more than 30% in the Western Atlantic, whereas in the key overwintering centre of the Norwegian Sea it changes only marginally. Surface temperature rises, which reduce body size and lipid reserves, will have a similar impact to deep water changes on diapause in many regions. Because deep water warming lags that at the surface, animals in the Labrador Sea could offset warming impacts by diapausing in deeper waters. However, the ability to control diapause depth may be limited