The effect of dietary calcium and other nutritionally relevant divalent cations on fatty acid-soap formation : a dissertation presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Nutritional Sciences at Massey University, Manawatū, New Zealand

A growing amount of scientific evidence appears to support a relationship between dietary calcium (Ca) and body weight where increased dietary Ca intake leads to weight reduction and the faecal excretion of several fatty acids. One possible mechanism, explaining the effect of dietary Ca on body weight and faecal fatty acid excretion, is the formation of indigestible Ca-fatty acid soaps within the gastrointestinal tract, leading to reduced fat and therefore reduced energy absorption. The objectives of this research were 1) to confirm that dietary Ca reduces fatty acid absorption and that the effect is via the formation of fatty acid soaps, 2) to explore the potential of cations other than Ca to form fatty acid soaps and 3) to investigate where in the gastrointestinal tract Ca-fatty acid soap formation occurs. In order to investigate the presence of fatty acid-soaps in the gastrointestinal tract, an assay was developed to determine fatty acid-soaps in digesta and faeces. Faecal fatty acid-soap excretion, apparent faecal fatty acid digestibility and apparent faecal Ca digestibility were determined in the growing pig for diets containing different sources of fat (tallow, palmolein oil, olive oil and soya bean oil) and increasing concentrations of Ca (0, 2, 4 and 6 g kg-1 diet). Increasing concentrations of dietary Ca resulted in increased faecal fatty acid excretion (P 80%) for diets containing a fat source rich in saturated fatty acids (tallow and palmolein oil). The fatty acid digestibility of these diets was reduced (P < 0.001) by up to 28% when the dietary Ca intake was increased from 0 g Ca kg-1 diet to 6 g Ca kg-1 diet. Moreover, faecal Ca output of the tallow-based diet, for which the fatty acid soap excretion was the greatest, was statistically higher when compared to the oil containing diets. These results provide evidence that supports the hypothesis that dietary Ca can impair fat absorption via the formation of indigestible Ca-fatty acid soaps but that the effect is largely limited to fat sources rich in saturated fatty acids as evidenced by the reduction in Ca absorption with tallow. Given that Ca appears to react with fatty acids to form soaps, it was decided to investigate whether other nutritionally relevant divalent cations (magnesium (Mg), zinc (Zn), iron (Fe) and copper (Cu)) were able to form fatty acid soaps. To that end, in vitro studies revealed that apart from Ca, other divalent cations such as Zn, Mg, Fe and Cu had the ability to form precipitates in the presence of fatty acids. In general, all the divalent cations examined formed precipitates in the presence of at least some of the fatty acids examined, although the extent to which the divalent cation-fatty acid precipitates (soaps) formed varied depending on the cation and fatty acid present. The precipitation of saturated fatty acids (lauric, myristic, palmitic and stearic acid) when incubated with Zn was comparable with that of Ca. However, the precipitation of unsaturated fatty acids (oleic and linoleic acid) with Zn was greater than that observed for Ca. For Fe and Cu, fatty acid precipitation was less than that observed for Ca. To investigate where in the gastrointestinal tract fatty acid soaps form, growing pigs were fed diets containing either free fatty acids or an intact triacylglyceride (tallow) and calcium carbonate as the Ca source. The amount of insoluble fatty acid-soap present in the gastrointestinal tract was determined at 10 different locations within the tract. The amount of fatty acid-soaps present increased (P < 0.05) at the distal jejunum when the free fatty acid-based diet was fed and at the ileum when pigs received the tallow-based diets, and was correlated with the pH (regardless the diet) of the gastrointestinal tract suggesting that soaps formed as the pH of the gastrointestinal tract increased. Fatty acid-soap formation in the small intestine of pigs receiving the free fatty acids was almost double than for pigs receiving tallow with their diet. There was little soap formation in the hind gut. With the majority of fatty acid soap formation occurring in the distal small intestine (the major absorption site of fatty acids) fatty acid-soap formation has the potential to reduce fatty acid absorption. Feeding a fat-free diet in addition to the two fat containing diets gave insight into mineral absorption in the absence and presence of dietary fat. The apparent digestibility of Ca, Mg, Zn and Fe was lower (P < 0.05) in the presence of dietary fat (free fatty acids or triacylglycerides) suggesting that the formation of divalent cation-fatty acid soaps may have the ability to impair the absorption of divalent cations other than Ca. In conclusion, high dietary Ca intake leads to increased faecal fatty acid excretion in the form of insoluble fatty acid-soaps. Fatty acid-soap formation can impair the digestibility of Ca and other nutritionally relevant divalent cations such as Zn, Mg and Fe. Moreover, fatty acid-soaps appear to form mainly in the distal small intestine and appear to be associated with gastrointestinal pH. These results contribute to the knowledge of where fatty acid soap formation occurs and provide evidence that fatty acid soap formation can reduce fat absorption and thereby possibly contribute to weight loss

Realizability of integer sequences as differences of fixed point count sequences

A sequence of non-negative integers is exactly realizable as the fixed point counts sequence of a dynamical system if and only if it gives rise to a sequence of non-negative orbit counts. This provides a simple realizability criterion based on the transformation between fixed point and orbit counts. Here, we extend the concept of exact realizability to realizability of integer sequences as differences of the two fixed point counts sequences originating from a dynamical system and a topological factor. A criterion analogous to the one for exact realizability is given and the structure of the resulting set of integer sequences is outlined.Comment: 7 page

Radon background in liquid xenon detectors

The radioactive daughters isotope of 222Rn are one of the highest risk contaminants in liquid xenon detectors aiming for a small signal rate. The noble gas is permanently emanated from the detector surfaces and mixed with the xenon target. Because of its long half-life 222Rn is homogeneously distributed in the target and its subsequent decays can mimic signal events. Since no shielding is possible this background source can be the dominant one in future large scale experiments. This article provides an overview of strategies used to mitigate this source of background by means of material selection and on-line radon removal techniques

’I learned about myself’: using blogs to foster self-reflection and collaborative learning.

Paper presentation on blogging at the Designs on e-Learning Conference UNCW, NC

Employee involvement in and perceptions of campus alcohol and drug abuse prevention programming at UW-Stout

Plan BNational research has continually shown that college campuses nationwide foster many alcohol and drug use behaviors. It is suggested that faculty and staff may hold several misperceptions in regard to the prevalence and nature of the alcohol and drug use. Many college campus employees may tolerate the use and abuse of alcohol and drugs which may in turn lead students to mistake tolerance for acceptance. This study was conducted to determine the level of difference for levels of perceptions of campus policy and the amount of tolerance for alcohol and drug use for employees at the University of Wisconsin-Stout. Participants completed the Faculty and Staff Environmental Alcohol and Other Drug Survey to measure both their level of perceptions and their level of tolerance. Results would be used to determine whether knowledge and awareness of campus policy would heighten awareness of alcohol and drug use on campus as well as decrease levels of tolerance in a college campus environment

Profit and purpose: the case for sustainable luxury fashion

The development of the fashion industry into a large-scale multinational operation and the resulting potential for damage to planet and people has attracted the attention of environmental and social activists since at least the 1960s, but consumers on the whole remain broadly ignorant of how their personal fashion purchases and widespread industry practices contribute to negative environmental and social impact (Connell and Kozar, 2014). The luxury sector, in particular, has much to lose in terms of reputation by revelations of exploitation and irresponsible environmental actions along the supply chain, given that much of its premium-pricing is based on notions of authenticity and quality production (Kapferer and Bastien, 2012). Previously, a focus on eco or sustainable fashion was seen as marginal or niche, but more recently consumers demonstrate a desire for greener products creating potential for businesses to work for profit and purpose (Ottman, 2011). This change has resulted in a new hybrid business model- the social enterprise- which adds value by meeting market needs and wants through responsible business and employment practices (Radclyffe-Thomas and Roncha, 2016). Tengri, a London-based luxury knitwear label is one such social enterprise business and this paper explores social enterprise in the luxury sector through a case study of Tengri’s business model that combines social and environmental awareness with luxury product development to create a virtuous cycle of ethical fashion production and consumption. Founder Nancy Johnston was inspired by her experiences travelling with Mongolia’s yak herders where she was confronted with the harshness of the nomadic way of life and threats to its continuing existence from land degradation and exploitative business practices. She was driven to action when she juxtaposed these conditions with the promoted glamour of the luxury fashion industry, which relies on supplies of ingredients from just such workers in supply chains that stretch across the globe. Informed by primary research with Tengri and industry experts supplemented with analysis of Tengri’s business, product development and marketing materials, this paper investigates how Tengri works to balance environmental and social engagement with launching a start-up luxury business aimed at engaging the new global sustainable luxury consumers, a group described by Caroline Holme Director of Globescan as the ‘Aspirational’ consumer – a segment that combines a desire to be ethical with a love of style, design and shopping, particularly prevalent in emerging markets. Keywords: sustainability, luxury, fashion, social-enterprise, innovatio