Empowering Students to Take Control Through Student Leadership Teams

As our educational system becomes more focused on personalizing learning for students, it is increasingly important for educators to empower students to take an active role in their learning and their communities. In this practitioner perspective, two educators reflect on the process of establishing student leadership teams in their school, and on the research that supports such efforts toward developing systems of student agency and self-advocacy in education

Signals of Early-Universe Physics in Cosmology

This is a thesis on theoretical cosmology. The first and largest part is a study of cosmic strings, in particular their dynamics and signals in higher dimensional spacetimes. The second part is a study of black holes in a quintessence background. Cosmic strings are predicted by models of the early universe. They were thought to arise, originally, from Grand Unified Theories, and more recently from brane inflationary models based in string theory. In Chapter 3 we find exact solutions for cosmic string loop trajectories in higher dimensions, and find the regions of parameter space for which cusps exist. We find that winding the internal dimensions slows the average velocity of string loops, and conjecture that the periodicity of internal space may contribute to self-intersections. In Chapter 4, we calculate the gravitational wave signal from cosmic string cusps in higher dimensions, and find it is much reduced relative to the 4D case. The main reason for this is the large reduction in the probability of cusps occurring on loops in higher dimensions, as well as a slight reduction in signal from individual cusps. In Chapter 5, we study cosmic string trajectories in warped spacetimes, such as may be found in realistic brane inflation models. We find that contrary to claims in the literature, the warping of the internal space does not prevent the internal motion of strings. The energy associated with the warping of spacetime means that the energy of a loop appears to change over time from our 4D perspective. Finally, in Chapter 6, we find an analytic, general-relativistic solution describing a black hole in a quintessence universe. Quintessence is a model of late-time cosmic acceleration in which expansion is sourced by a scalar field. Our solution shows the interaction between this scalar field and a black hole. The scalar field is shown to continue its cosmological "rolling" behaviour everywhere, including on the black hole event horizon, and the black hole is shown slowly to accrete scalar field. This is a perturbative solution valid throughout all of space but only over a finite period of time

Managing the Relative Volumes of Participating and Nonparticipating Business in a Mutual Life Company

Management decisions of a mutual life company involving the amounts and relative proportions of participating (with profits) and nonparticipating (without profits) business and the level of expenses are examined in relation to their effect on participating policyholders\u27 returns. A particular expense ratio is defined that plays a key role in a framework for making such decisions. The sensitivity of participating policy returns to changes in each factor are analyzed. Companies with expense ratios (as defined) of less than 2 are shown to prefer a different strategy from companies with higher ratios. There is an incomplete tendency for the ratio to stabilize either at unity or to tend to infinity. The practical implications and limitations of the approach are considered

A vertical representation of soil carbon in the JULES land surface scheme (vn4.3_permafrost) with a focus on permafrost regions

An improved representation of the carbon cycle in permafrost regions will enable more realistic projections of the future climate–carbon system. Currently JULES (the Joint UK Land Environment Simulator) – the land surface model of the UK Earth System Model (UKESM) – uses the standard four-pool RothC soil carbon model. This paper describes a new version of JULES (vn4.3_permafrost) in which the soil vertical dimension is added to the soil carbon model, with a set of four pools in every soil layer. The respiration rate in each soil layer depends on the temperature and moisture conditions in that layer. Cryoturbation/bioturbation processes, which transfer soil carbon between layers, are represented by diffusive mixing. The litter inputs and the soil respiration are both parametrized to decrease with increasing depth. The model now includes a tracer so that selected soil carbon can be labelled and tracked through a simulation. Simulations show an improvement in the large-scale horizontal and vertical distribution of soil carbon over the standard version of JULES (vn4.3). Like the standard version of JULES, the vertically discretized model is still unable to simulate enough soil carbon in the tundra regions. This is in part because JULES underestimates the plant productivity over the tundra, but also because not all of the processes relevant for the accumulation of permafrost carbon, such as peat development, are included in the model. In comparison with the standard model, the vertically discretized model shows a delay in the onset of soil respiration in the spring, resulting in an increased net uptake of carbon during this time. In order to provide a more suitable representation of permafrost carbon for quantifying the permafrost carbon feedback within UKESM, the deep soil carbon in the permafrost region (below 1 m) was initialized using the observed soil carbon. There is now a slight drift in the soil carbon ( <  0.018 % decade−1), but the change in simulated soil carbon over the 20th century, when there is little climate change, is comparable to the original vertically discretized model and significantly larger than the drift

Using a Social Justice Lens to Connect the Past with the Present in a Personalized Learning Environment

This practitioner perspective describes how middle grades units are developed and revised in response to student needs to engage students in social justice work while maintaining a safe and respectful classroom culture. In order for students to understand the world around them, they need to develop context by studying the past. There is no better way to enable students to do this in a personalized learning environment than to explore both the past and present through the lens of social justice. Broad, thematic units, such as “Revolution,” “Race in America,” or “Societal Monsters” allow teachers to ensure that students are able to analyze and reflect on the injustices of the past, as well as understand how those injustices have changed and shifted to become the ones we see and experience in our modern world. At the same time, personalized learning allows students the freedom to choose topics within these broad themes and learning pathways that suit their interests, skills, and needs as individuals