Kinetic ferromagnetism on a kagome lattice

We study strongly correlated electrons on a kagome lattice at 1/6 and 1/3 filling. They are described by an extended Hubbard Hamiltonian. We are concerned with the limit |t|<<V<<U with hopping amplitude t, nearest-neighbor repulsion V and on-site repulsion U. We derive an effective Hamiltonian and show, with the help of the Perron-Frobenius theorem, that the system is ferromagnetic at low temperatures. The robustness of ferromagnetism is discussed and extensions to other lattices are indicated.Comment: 4 pages, 2 color eps figures; updated version published in Phys. Rev. Lett.; one reference adde

Analyses of diverse stresses, including hypoxia, cyanide, and hypergravity in Caenorhabditis elegans

Organisms often encounter various forms of stress during their lifespan. The response to stress involves the regulation of cellular processes by stress response modulators that function to ultimately enable resistance and survival. In this dissertation I used Caenorhabditis elegans as a model to study the effects of a variety of stresses including the response to cyanide, hypoxia, and hypergravity. Chapter 2 of this thesis focuses on understanding the mechanisms of cyanide resistance in C. elegans. We employed a novel microfluidic device to describe the resistance phenotypes with greater spatio-temporal resolution. The results shed light on the underlying genetic bases that contribute to cyanide resistance, including the role of the hypoxia-inducible factor HIF-1. They also reveal new findings about the cyanide resistance phenotype, and help establish the applicability of microfluidic devices in studying the effects of aqueous toxicants in real-time. Chapter 3 is a study investigating the crosstalk between the stress response modulators HIF-1, DAF-16, and HLH29 in C. elegans. We found significant over-representation of DAF-16 target genes, as well as HLH29 target genes in our lists of genes up- or down- regulated by hypoxia or in animals with over-active HIF-1. Genes identified in this study are known to play important roles in the response and resistance to diverse forms of stress. The findings from this study illustrate the complex mechanisms employed by cells to regulate the expression of subsets of genes in the response to specific forms of stress. In chapter 4 we studied the effects of hypergravity exposure on C. elegans mobility, behavior, reproduction, and lifespan. We found that the animals rapidly recoverered mobility after short, intense bouts of hypergravity exposure, but their reproductive capabilities and lifespans were altered after longer durations of treatment. The results suggest that long term exposure to stress in the form of hypergravity may be detrimental to the animal\u27s health and physiology. Collectively, the results from my thesis help elucidate the important roles played by stress response mediators in contributing to an organism\u27s survival. They also illustrate the rich and complex ways in which organisms modulate their responses to various forms of stress

The Role of Nutraceuticals in Chemoprevention and Chemotherapy and Their Clinical Outcomes

The genesis of cancer is often a slow process and the risk of developing cancer increases with age. Altering a diet that includes consumption of beneficial phytochemicals can influence the balance and availability of dietary chemopreventive agents. In chemopreventive approaches, foods containing chemicals that have anticancer properties can be supplemented in diets to prevent precancerous lesions from occurring. This necessitates further understanding of how phytochemicals can potently maintain healthy cells. Fortunately there is a plethora of plant-based phytochemicals although few of them are well studied in terms of their application as cancer chemopreventive and therapeutic agents. In this analysis we will examine phytochemicals that have strong chemopreventive and therapeutic properties in vitro as well as the design and modification of these bioactive compounds for preclinical and clinical applications. The increasing potential of combinational approaches using more than one bioactive dietary compound in chemoprevention or cancer therapy will also be evaluated. Many novel approaches to cancer prevention are on the horizon, several of which are showing great promise in saving lives in a cost-effective manner

The Plausibility of a String Quartet Performance in Virtual Reality

We describe an experiment that explores the contribution of auditory and other features to the illusion of plausibility in a virtual environment that depicts the performance of a string quartet. ‘Plausibility’ refers to the component of presence that is the illusion that the perceived events in the virtual environment are really happening. The features studied were: Gaze (the musicians ignored the participant, the musicians sometimes looked towards and followed the participant’s movements), Sound Spatialization (Mono, Stereo, Spatial), Auralization (no sound reflections, reflections corresponding to a room larger than the one perceived, reflections that exactly matched the virtual room), and Environment (no sound from outside of the room, birdsong and wind corresponding to the outside scene). We adopted the methodology based on color matching theory, where 20 participants were first able to assess their feeling of plausibility in the environment with each of the four features at their highest setting. Then five times participants started from a low setting on all features and were able to make transitions from one system configuration to another until they matched their original feeling of plausibility. From these transitions a Markov transition matrix was constructed, and also probabilities of a match conditional on feature configuration. The results show that Environment and Gaze were individually the most important factors influencing the level of plausibility. The highest probability transitions were to improve Environment and Gaze, and then Auralization and Spatialization. We present this work as both a contribution to the methodology of assessing presence without questionnaires, and showing how various aspects of a musical performance can influence plausibility

The role of attachment in endorsements

Endorsement research has predominantly focused on how the effectiveness of an endorsement is affected by variation in an endorser&amp;rsquo;s characteristics, such as their appeal, attractiveness, trustworthiness and expertise, and more importantly, on their congruence with the endorsed product, and credibility as endorsers. However, there is little or no research on how the perceived commitment of the celebrity to the product affects the celebrity&amp;rsquo;s level of attachment to the endorsed product and thereby endorsement effectiveness. The following thesis considers this aspect of product endorsements and identifies six categories of endorsement situations based on the types of endorsement and endorsers. It seeks to emphasise the importance of attachment between a product and the endorser, and its subsequent impact on consumer perceptions. The tripartite attachment model is introduced in this thesis, which introduces three attachment nodes in an endorsement, viz., attachment between the consumer and product, between the consumer and celebrity and between the celebrity and product. Attachment between the consumer and celebrity and between the consumer and product has been extensively examined. However, there is little or no research on the perceived attachment between the celebrity and product. The thesis focuses on this attachment node by introducing the progenic brand: a brand launched by endorsers wherein the endorser&amp;rsquo;s name and values are imbued in the brand. The attachment theory was used to identify the endorsed, spokesperson and progenic, as the three primary types of endorsement situations associated with two types of endorsers, namely, celebrities and Chief Executive Officers (CEOs). Using the source credibility model, it is hypothesised how the three appeals of attractiveness, trustworthiness and expertise vary across six endorsement situations and the subsequent implications for marketing practitioners. A new brand term called &amp;lsquo;progenic&amp;rsquo; is introduced which has been shown to have higher perceived attachment between the endorser and product compared to traditional endorsements. Finally, this research not only contributes theoretically by distinguishing between endorsement situations but can also assist practitioners when pairing the right type of individual with a specific product-type, and in distinguishing between product appeals

Family experiences of infant and young child feeding in lower-income countries: protocol for a systematic review of qualitative studies

PRISMA-P checklist. Completed checklist indicating inclusion of items noted. (DOCX 128 kb

Introductory biology undergraduate students\u27 mixed ideas about genetic information flow

The core concept of genetic information flow was identified in recent calls to improve undergraduate biology education. Previous work shows that students have difficulty differentiating between the three processes of the Central Dogma (CD; replication, transcription, and translation). We built upon this work by developing and applying an analytic coding rubric to 1050 student written responses to a three‐question item about the CD. Each response was previously coded only for correctness using a holistic rubric. Our rubric captures subtleties of student conceptual understanding of each process that previous work has not yet captured at a large scale. Regardless of holistic correctness scores, student responses included five or six distinct ideas. By analyzing common co‐occurring rubric categories in student responses, we found a common pair representing two normative ideas about the molecules produced by each CD process. By applying analytic coding to student responses preinstruction and postinstruction, we found student thinking about the processes involved was most prone to change. The combined strengths of analytic and holistic rubrics allow us to reveal mixed ideas about the CD processes and provide a detailed picture of which conceptual ideas students draw upon when explaining each CD process