Approximation Algorithms for Polynomial-Expansion and Low-Density Graphs

We study the family of intersection graphs of low density objects in low dimensional Euclidean space. This family is quite general, and includes planar graphs. We prove that such graphs have small separators. Next, we present efficient $(1+\varepsilon)$-approximation algorithms for these graphs, for Independent Set, Set Cover, and Dominating Set problems, among others. We also prove corresponding hardness of approximation for some of these optimization problems, providing a characterization of their intractability in terms of density

Organic food in schools and kindergartens in Trondheim. A case study report.

In October 2007, the municipality of Trondheim, Norway decided to increase the public consumption of organic food. The share of public schools and kindergartens offering organic food should be increased by 20 % within 2011, as compared to 2007. Trondheim has for several years had an ambitious aim to increase the consciousness among children and youth about environmental issues, and the project “Children‟s Green City” had been an important tool in this work. The decision made it relevant for the research project “innovative Public Organic food Procurement for Youth” (iPOPY) to use Trondheim as a research case. This report describes the background for the municipal decision about organic food, and what has been done to implement it. Several employees in the municipality and other stakeholders have been interviewed. Even if the decision puts up a quite modest goal, there are several challenges to achieve it. The point of departure (how much organic food was served by kindergartens and schools in 2007) is unknown, and hence the progress is difficult to measure. In the public purchasing agreement, the municipality has obliged its appointed wholesaler to offer organic products. The intention was that the units (e.g. schools) would get easier access to organic food, and that the demand would increase, making it possible for more local farmers to convert to organic. Purchasing agreements are an important tool, but they have to be carefully designed and developed with time. The largest challenge to achieve the organic goal in Trondheim is to motivate actors who may influence the purchase of food, and to anchor the intentions in the decision in such a large organisation as the municipality is. A committed and continuous effort is required. Education and training of staff in charge of food serving in schools and kindergartens is a fruitfu

Generalized Tur\'an problems for even cycles

Given a graph $H$ and a set of graphs $\mathcal F$, let $ex(n,H,\mathcal F)$ denote the maximum possible number of copies of $H$ in an $\mathcal F$-free graph on $n$ vertices. We investigate the function $ex(n,H,\mathcal F)$, when $H$ and members of $\mathcal F$ are cycles. Let $C_k$ denote the cycle of length $k$ and let $\mathscr C_k=\{C_3,C_4,\ldots,C_k\}$. Some of our main results are the following. (i) We show that $ex(n, C_{2l}, C_{2k}) = \Theta(n^l)$ for any $l, k \ge 2$. Moreover, we determine it asymptotically in the following cases: We show that $ex(n,C_4,C_{2k}) = (1+o(1)) \frac{(k-1)(k-2)}{4} n^2$ and that the maximum possible number of $C_6$'s in a $C_8$-free bipartite graph is $n^3 + O(n^{5/2})$. (ii) Solymosi and Wong proved that if Erd\H{o}s's Girth Conjecture holds, then for any $l \ge 3$ we have $ex(n,C_{2l},\mathscr C_{2l-1})=\Theta(n^{2l/(l-1)})$. We prove that forbidding any other even cycle decreases the number of $C_{2l}$'s significantly: For any $k > l$, we have $ex(n,C_{2l},\mathscr C_{2l-1} \cup \{C_{2k}\})=\Theta(n^2).$ More generally, we show that for any $k > l$ and $m \ge 2$ such that $2k \neq ml$, we have $ex(n,C_{ml},\mathscr C_{2l-1} \cup \{C_{2k}\})=\Theta(n^m).$ (iii) We prove $ex(n,C_{2l+1},\mathscr C_{2l})=\Theta(n^{2+1/l}),$ provided a strong version of Erd\H{o}s's Girth Conjecture holds (which is known to be true when $l = 2, 3, 5$). Moreover, forbidding one more cycle decreases the number of $C_{2l+1}$'s significantly: More precisely, we have $ex(n, C_{2l+1}, \mathscr C_{2l} \cup \{C_{2k}\}) = O(n^{2-\frac{1}{l+1}}),$ and $ex(n, C_{2l+1}, \mathscr C_{2l} \cup \{C_{2k+1}\}) = O(n^2)$ for $l > k \ge 2$. (iv) We also study the maximum number of paths of given length in a $C_k$-free graph, and prove asymptotically sharp bounds in some cases.Comment: 37 Pages; Substantially revised, contains several new results. Mistakes corrected based on the suggestions of a refere

BIODIESEL: WILL THERE BE ENOUGH?

Resource /Energy Economics and Policy,

Conformity to Gender Stereotypes Impacting Body-Esteem, Eating, and Exercise Behaviors in Female College Students

Conformity to gender stereotypes and the impacts they may have on body-esteem, eating, and exercise behaviors have always been a very important topic in society because of the mental, physical and emotional problems that could arise. In society today, it is extremely unlikely to go a day without hearing or seeing something about eating healthy, exercising, or performing the correct “role”. With this increased pressure from the media and peers, conforming to the stereotypes in society can impact someone beyond what they may believe possible or even realize. A stereotype is a widely held and oversimplified image or idea of a particular person or thing. It is a preconceived notion that is generally conceptualized to an entire group of individuals or behaviors, which tend to be inaccurate and potentially harmful. The purpose of this study is to examine the link between gender stereotype adherence and body-esteem, eating, and exercise behaviors. Multiple regression analyses are used to examine a sample of 248 female college students. Findings reveal that several female gender stereotypes have effects on bodyesteem,eating and exercise behaviors. Of particular significance was the stereotype that females should strive to be thin

Polyols in confectionery: the route to sugar-free, reduced sugar and reduced calorie confectionery

Polyol-containing confectionery offers considerable advantages over traditional sucrose-based confectionery in terms of reduced energy content and reduced cariogenicity. However, over-consumption of polyol confectionery may lead to gastrointestinal symptoms in some individuals. Rather than consider this as a distinct disadvantage to the consumer, this article discusses how careful consideration of the physico-chemical properties of polyols and advances in product development and formulation can provide suitable polyol-based products for the consumer. Furthermore. food legislation and ingredient pricing issues are just some of the factors that must be taken into account when designing new polyol-containing products if their functional benefits and good product quality are to be delivered to the consumer

The Privilege of Healthy Eating: A Qualitative Study Exploring the Local Food Choices of Low-Income Families from Appalachia

Using qualitative semi-structured interviews, 15 low-income women of different ages were asked to discuss their perceptions of healthy eating, local farmers’ markets, as well as their visitation of farmers’ markets. The participants were also asked to share what features of farmers’ markets they found appealing. The results showed that most of the participants had either a deep or moderate understanding of what it means to eat healthy. However, many of them also believed they could improve their own patterns of eating. The data also showed that the low-income women who took part in the study had positive attitudes overall toward local farmers’ markets, despite rather low levels of visitation (only 5 participants had visited farmers’ market at least once and only one of them visited farmers’ market on a regular basis). Lastly, participants discussed constraints that prevented them from visiting farmers’ markets more often and provided suggestions for possible facilitators to increase the frequency of their use of farmers’ markets

Korean Consumers’ Preferences and Willingness to Pay for Domestic versus U.S. and Australian Beef with Alternative Attributes

In 2007, consumer focus groups and online surveys using choice sets were conducted to examine South Korean’s perceptions of and willingness-to-pay for Australian, U.S. and domestic beef. Consumers indicated higher positive perceptions of Australian beef than of U.S. beef, particularly in the area of environmentally friendly, cleanliness, standards and credibility; and thus Korean consumers discount Australian beef less than U.S. beef relative to domestic beef. The U.S. industry could improve perceptions and their country-image by providing Korean consumers with promotional material pointing out that U.S. beef production systems are comparable to competitors’ in terms of “environmental-friendliness” and other quality attributes.Demand and Price Analysis, Food Consumption/Nutrition/Food Safety,