Elementary Student Knowledge Gains In The Digital Portable Planetarium

Immersive environments provide unique and heightened sensory experiences that focus a learner’s attention, and thus may be useful learning platforms.  In particular, portable planetariums may be useful in advancing conceptual knowledge about the night sky, because they afford learners with Earth-based views of celestial motions, and give learners a sense of “being there.”  We demonstrate here that students make gains in knowledge about both apparent celestial motion and general astronomy concepts after viewing a 25-minute planetarium presentation.  However, the planetarium presentation did not appear to increase interest in astronomy and space science.  Our results suggest that the portable planetarium may be a useful strategy in supporting learners as they struggle with reconciling observed patterns with underlying, non-observable motions of the Earth, and with visualizing concepts such as the speed of planetary orbits relative to their position with respect to the sun

Embracing materiality as a core element of Arctic pedagogy

This material is based in part upon work supported by the National Science Foundation under Grant No. DRL 1224020. We thank NSF for their support of this work. This work was also supported by the Engineering and Physical Sciences Research Council [grant number EP/X525820/1]. We thank the Council for its support of this work. This research was part of the project “DiSSI – Diversity in Science towards Social inclusion – non-formal education for students' diversity” that is co-funded by the Erasmus+ Programme of the European Union, under the grant number 612103-EPP-1_2019-1-DE-EPPKA3-IPI-SOC-IN. We would like to thank the European Union for its financial support. The European Commission’s support for the production of this publication does not constitute an endorsement of the contents, which reflect the views only of the authors, and the Commission cannot be held responsible for any use which may be made of the information contained therein.Peer reviewedPublisher PD

Embracing materiality as a core element of Arctic pedagogy

Arctic pedagogy has arisen as a distinct set of practices that are particularly relevant for learners in northern regions. Here, we advocate to expand notions of Arctic pedagogy by formally including theories of materiality and sensory engagement into the framework. We posit that materiality, especially when place-based, offers a route to mediate and connect learners with emotion and culture, as well as disciplinary content. This paper presents four different examples of learning activities in northern settings, three of which use specific place-based materials as the basis for investigations, and one that was place-based in narrative but did not focus on direct place-based material engagement. Data sources were different for each intervention, including pre and post data capture via postcards, questionnaires, and/or participant interviews. The findings across the first three cases indicate that the activities that richly drew from local materials and contexts and that included sensory elements afforded learning in the affective or identity-related realms. These results contrasted with the fourth activity, in which the learning was largely content based. The combined results underscore the value of direct, hands-on exploration of materials of local significance within northern pedagogical contexts

The Role of Context in Investment into Reproductive Tissue and Implications for Mating

Reproductive traits are often thought of as fixed, genetically determined properties. However, such traits are often dynamic, exhibiting different expression patterns depending on context. Both internal state and external environment can have a strong effect on how traits are expressed. Variation in these factors across the lifetime of an individual should select for flexibility in trait expression, rather than fixation.My dissertation work examines how mating behavior and testes size respond to several previously unexplored contextual factors, using Rhagoletis juglandis, the walnut fly, as a model system. For mating behavior, I predicted that differences in female reproductive state (egg load) and experience with host resource would impact mating decisions. For testes size, I predicted that social environment (sex ratio) and changes in resource environment would determine testes size.Behavioral observations of flies showed that a large egg load increased the likelihood of copulation, while prior experience with host fruit decreased copulation time. These results are the first to distinguish effects of experience on physiological state from other effects of experience in the context of mating behavior.Manipulation of the sex ratio revealed that males develop larger testes when reared in an environment with many potential competitors. This is the first study to show that that allocation to a male reproductive organ can change depending on the sex ratio. My studies showed that resource environment is also important in determining testes investment patterns. When adult males are deprived of protein, they develop smaller testes. A stable isotope analysis of testes further confirms that resource environment is important for testes development. Males rely more on nitrogen derived at the larval stage than at the adult stage, but adult carbon sources are a large component of testes mass.In sum, this dissertation demonstrates the importance of context in the expression of reproductive traits. Recent research has shown that such traits can respond more dynamically to context than previously thought, but this area of research is young. My results help provide a greater understanding of the processes shaping the evolution of reproductive traits

Elementary Student Knowledge Gains In The Digital Portable Planetarium

Immersive environments provide unique and heightened sensory experiences that focus a learner’s attention, and thus may be useful learning platforms. In particular, portable planetariums may be useful in advancing conceptual knowledge about the night sky, because they afford learners with Earth-based views of celestial motions, and give learners a sense of “being there.” We demonstrate here that students make gains in knowledge about both apparent celestial motion and general astronomy concepts after viewing a 25-minute planetarium presentation. However, the planetarium presentation did not appear to increase interest in astronomy and space science. Our results suggest that the portable planetarium may be a useful strategy in supporting learners as they struggle with reconciling observed patterns with underlying, non-observable motions of the Earth, and with visualizing concepts such as the speed of planetary orbits relative to their position with respect to the sun

Radical-Translocation Intermediates and Hurdling of Pathway Defects in “Super-oxidized” (Mn^IV/Fe^IV) <i>Chlamydia trachomatis</i> Ribonucleotide Reductase

A class I ribonucleotide reductase (RNR) uses either a tyrosyl radical (Y^•) or a Mn^IV/Fe^III cluster in its β subunit to oxidize a cysteine residue ∼35 Å away in its α subunit, generating a thiyl radical that abstracts hydrogen (H^•) from the substrate. With either oxidant, the inter-subunit “hole-transfer” or “radical-translocation” (RT) process is thought to occur by a “hopping” mechanism involving multiple tyrosyl (and perhaps one tryptophanyl) radical intermediates along a specific pathway. The hopping intermediates have never been directly detected in a Mn/Fe-dependent (class Ic) RNR nor in <i>any</i> wild-type (wt) RNR. The Mn^IV/Fe^III cofactor of <i>Chlamydia trachomatis</i> RNR assembles via a Mn^IV/Fe^IV intermediate. Here we show that this cofactor-assembly intermediate can propagate a hole into the RT pathway when α is present, accumulating radicals with EPR spectra characteristic of Y^•’s. The dependence of Y^• accumulation on the presence of substrate suggests that RT within this “super-oxidized” enzyme form is gated by the protein, and the failure of a β variant having the subunit-interfacial pathway Y substituted by phenylalanine to support radical accumulation implies that the Y^•(s) in the wt enzyme reside(s) within the RT pathway. Remarkably, two variant β proteins having pathway substitutions rendering them inactive in their Mn^IV/Fe^III states can generate the pathway Y^•’s in their Mn^IV/Fe^IV states and <i>also effect nucleotide reduction</i>. Thus, the use of the more oxidized cofactor permits the accumulation of hopping intermediates and the “hurdling” of engineered defects in the RT pathway

O₂-Evolving Chlorite Dismutase as a Tool for Studying O₂-Utilizing Enzymes

The direct interrogation of fleeting intermediates by rapid-mixing kinetic methods has significantly advanced our understanding of enzymes that utilize dioxygen. The gas’s modest aqueous solubility (<2 mM at 1 atm) presents a technical challenge to this approach, because it limits the rate of formation and extent of accumulation of intermediates. This challenge can be overcome by use of the heme enzyme chlorite dismutase (Cld) for the rapid, <i>in situ</i> generation of O₂ at concentrations far exceeding 2 mM. This method was used to define the O₂ concentration dependence of the reaction of the class Ic ribonucleotide reductase (RNR) from <i>Chlamydia trachomatis</i>, in which the enzyme’s Mn^IV/Fe^III cofactor forms from a Mn^II/Fe^II complex and O₂ via a Mn^IV/Fe^IV intermediate, at effective O₂ concentrations as high as ∼10 mM. With a more soluble receptor, myoglobin, an O₂ adduct accumulated to a concentration of >6 mM in <15 ms. Finally, the C–H-bond-cleaving Fe^IV–oxo complex, <b>J</b>, in taurine:α-ketoglutarate dioxygenase and superoxo–Fe₂^III/III complex, <b>G</b>, in <i>myo</i>-inositol oxygenase, and the tyrosyl-radical-generating Fe₂^III/IV intermediate, <b>X</b>, in <i>Escherichia coli</i> RNR, were all accumulated to yields more than twice those previously attained. This means of <i>in situ</i> O₂ evolution permits a >5 mM “pulse” of O₂ to be generated in <1 ms at the easily accessible Cld concentration of 50 μM. It should therefore significantly extend the range of kinetic and spectroscopic experiments that can routinely be undertaken in the study of these enzymes and could also facilitate resolution of mechanistic pathways in cases of either sluggish or thermodynamically unfavorable O₂ addition steps