Hessians and Steinerians of plane quartic curves

Thesis (M.A.)--University of Kansas, Mathematics, 1916. ; Includes bibliographical references

An Investigation of Malaysian Secondary School Students’ Mental Models of Acid-Base Chemistry

There are many studies in chemistry investigating students’ difficulties in understanding chemical bonding, particle nature of matter and others, but relatively few on acid-base chemistry. One approach for reducing students’ learning difficulties uses model-based science teaching, which involves models and mental models. This thesis study investigates students’ mental models in acid-base chemistry concepts to give insights into Malaysian secondary students’ thinking in acid-base chemistry. In addition, teachers’ mental models and the curricular models were also examined in order to explore the degree of alignment between the three models. At Forms 2, 4, and 6 levels of Malaysian schooling eight secondary school students and two teachers were interviewed at each level in an effort to examine their mental models using the Interview-About-Concepts and Interview- About-Instances data gathering methods. In addition, Forms 2, 4 and 6 curricular models (i.e., curriculum documents) were examined to obtain insights into the curricular models. The area under investigation for this thesis study involves six selected acid-base chemistry concepts and their links to four acid-base models. The six selected acid-base chemistry concepts are Macroscopic Properties, Neutralisation, Acid-Strength, Acid-Base Equilibrium, Buffers, and Acid-Base Electron Pair Bonding while the four acid-base models are the Phenomenological, Arrhenius, Brønsted-Lowry, and Lewis models. To determine the nature of students’ mental models, attributes of these models were identified and gathered from students’ expressed models, that is their responses to probe questions about the selected acid-base concepts and compared with the attributes of each scientific acid-base models. This comparison provided evidence of students’ use/non-use of the attributes of the appropriate acid-base models to explain six selected acid-base chemistry concepts. Next, a mental model framework was developed and used to classify students’ attributes into Stage 1, Stage 2, and Stage 3 mental models. The Stage 1 mental model was developed based on the Macroscopic Properties acid-base chemistry concept to indicate students’ use or non–use of the Phenomenological model. The Stage 2 mental model was developed to determine students’ use or non-use of the Arrhenius model to explain the Neutralisation and Acid-Strength concepts. The Stage 3 mental model comprising the Acid-Base Equilibrium, Buffers, and Acid-Base Electron Pair Bonding concepts were investigated to identify students’ use or non-use of the Brønsted-Lowry and the Lewis model. Also, under investigation was a comparison of students’ mental models with teachers’ mental models and the curricular model. At Form 6 schooling level the students’ mental models demonstrated complete dissonance with the teachers’ mental models and the curricular models. The causes for this dissonance may be the lack of specificity in the Malaysian curriculum, students’ limited cognitive ability in terms of age-approriate concepts, and insufficient teachers’ pedagogical knowledge. From the findings of this thesis study, it is recommended that the Lewis acid-base model, be omitted from the Form 6 Malaysian curriculum because students’ were not able to understand Acid-Base Electron Pair Bonding chemistry concept. Also, for other acid-base chemistry concepts, Malaysian teachers are encouraged to use student-centred teaching methods utilizing acid-base models to help improve their students’ understanding

Lipid-laden partially-activated plasmacytoid and CD4-CD8a+ dendritic cells accumulate in tissues in elderly mice

Background - Aging is associated with a decline in lymphocyte function however, little is known about dendritic cell (DC) subsets and aging. Aging is also associated with increasing circulating lipid levels and intracellular lipid accumulation modulates DC function. Whether age-associated increases in lipid levels influence DC biology is unknown. Thus, the effects of aging on DC subsets were assessed in vivo using young adult and elderly C57BL/6 J mice. Results - Major age-related changes included increased CD11c+ DC numbers in lymph nodes, spleens and livers, but not lungs, and significantly increased proportions of plasmacytoid (pDC) and CD4-CD8α+ DCs in lymph nodes and livers. Other changes included altered pDC activation status (decreased CD40, increased MHC class-I and MHC class-II), increased lipid content in pDCs and CD4-CD8α+ DCs, and increased expression of key mediators of lipid uptake including lipoprotein lipase, scavenger receptors (CD36, CD68 and LRP-1) in most tissues. Conclusions - Aging is associated with organ-specific numerical changes in DC subsets, and DC activation status, and increased lipid content in pDCs and CD4-CD8α+ DCs. Up-regulation of lipoprotein lipase and scavenger receptors by lipid-rich pDCs and CD4-CD8α+ DCs suggests these molecules contribute to DC lipid accumulation in the elderly. Lipid accumulation and modulated activation in pDCs and CD4-CD8α+ DCs may contribute to the declining responses to vaccination and infection with age

Compte rendu du colloque international autour de Edgar Morin

Les « 4èmes rencontres de socio-anthropologie de Grenoble », organisées par le laboratoire emc2-lsg – Université Pierre Mendès‑France sous la direction de Florent Gaudez, avaient cette année pour invité d’honneur Edgar Morin, fondateur de la « pensée complexe », dont il expose les principes dans son œuvre majeure qu’est La méthode (2008). Une vaste pensée qui, sous l’œil attentif et vif de son auteur, a été approchée au travers de quatre thématiques de séance, évoquant certaines préoccupation..

Localism and energy: Negotiating approaches to embedding resilience in energy systems

Tensions are evident in energy policy objectives between centralised top-down interconnected energy systems and localised distributed approaches. Examination of these tensions indicates that a localised approach can address a systemic problem of interconnected systems; namely vulnerability. The challenge for energy policy is to realise the interrelated goals of energy security, climate and environmental targets and social and economic issues such as fuel poverty, whilst mitigating vulnerability. The effectiveness of conventional approaches is debateable. A transition to a low carbon pathway should focus on resilience, counter to vulnerability. This article draws from on-going work which evaluates the energy aspects of a Private Finance Initiative (PFI) project to refurbish and re-build a local authority’s entire stock of sheltered accommodation to high environmental standards. Initial findings suggest that whereas more conventional procurement processes tend to increase systemic vulnerability, a user focussed process driven through PFI competitive dialogue is beginning to motivate some developers to adopt innovative approaches to energy system development. Conceptually these findings strongly suggest that embedding ‘Open Source’ principles in energy system development acts to work against systemic vulnerabilities by embedding resilience

Veronese Geometry and the Electroweak Vacuum Moduli Space

We explain the origin of the Veronese surface in the vacuum moduli space geometry of the MSSM electroweak sector. While this result appeared many years ago using techniques of computational algebraic geometry, it has never been demonstrated analytically. Here, we present an analytical derivation of the vacuum geometry of the electroweak theory by understanding how the F- and D-term relations lead to the Veronese surface. We moreover give a detailed description of this geometry, realising an extra branch as a zero-dimensional point when quadratic Higgs lifting deformations are incorporated into the superpotential