Biosurfactants as Agents to Reduce Adhesion of Pathogenic Bacteria to Polystyrene Surfaces: Effect of Temperature and Hydrophobicity

Polystyrene surfaces were conditioned with surfactin and rhamnolipid biosurfactants and then assessed regarding the attachment of Staphylococcus aureus, Listeria monocytogenes, and Micrococcus lute us. The effect of different temperatures (35, 25, and 4 degrees C) on the anti-adhesive activity was also studied. Microbial adhesion to solvents and contact angle measurements were performed to characterize bacteria and material surfaces. The results showed that surfactin was able to inhibit bacterial adhesion in all the conditions analyzed, giving a 63-66% adhesion reduction in the bacterial strains at 4 degrees C. Rhamnolipid promoted a slight decrease in the attachment of S. aureus. The anti-adhesive activity of surfactin increased with the decrease in temperature, showing that this is an important parameter to be considered in surface conditioning tests. Surfactin showed good potential as an anti-adhesive compound that can be explored to protect surfaces from microbial contamination.

Temperature and common-ion effect on magnesium oxide (MgO) hydration

MgO based refractory castables draw wide technological interest because they have the versatility and installation advantages of monolithic refractories with intrinsic MgO properties, such as high refractoriness and resistance to basic slag corrosion. Nevertheless, MgO easily reacts with water to produce Mg(OH)(2), which is followed by a large volumetric expansion, limiting its application in refractory castables. In order to develop solutions to minimize this effect, a better understanding of the main variables involved in this reaction is required. In this work, the influence of temperature, as well as the impact of the chemical equilibrium shifting (known as the common-ion effect), on MgO hydration was evaluated. Ionic conductivity measurements at different temperatures showed that the MgO hydration reaction is accelerated with increasing temperature. Additionally, different compounds were added to evaluate their influence on the reaction rate. Among them, CaCl(2) delayed the reaction, whereas KOH showed an opposite behavior. MgCl(2) and MgSO(4) presented similar results and two other distinct effects, reaction delay and acceleration, which depended on their concentration in the suspensions. The results were evaluated by considering the kinetics and the thermodynamics of the reaction, and the mechanical damages in the samples that was caused by the hydration reaction. (C) 2009 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

Making modern lives: subjectivity, schooling and social change

Making Modern Lives looks at how young people shape their lives as they move through their secondary school years and into the world beyond. It explores how they develop dispositions, attitudes, identities, and orientations in modern society. Based on an eight-year study consisting of more the 350 in-depth interviews with young Australians from diverse backgrounds, the book reveals the effects of schooling and of local school cultures on young people's choices, future plans, political values, friendships, and attitudes toward school, work, and sense of self. Making Modern Lives uncovers who young people are today, what type of identities and inequalities are being formed and reformed, and what processes and politics are at work in relation to gender, class, race, and the framing of vocational futures.

It makes you realize, really, just how deep your subtext is : Literature, subjectivity and curriculum change

This paper draws on the notion of discourse to explore complex relationships between teachers and curriculum change. It uses poststructuralist views of discourse to explore ways in which school subjects, such as Literature, are discursively constructed across time, while teachers too are positioned within discourses that shape the ways they understand the subject and themselves as teachers of it. This paper reports on the experience of a small group of teachers of a new literature course in the Australian state of Victoria. Nine teachers were interviewed over 3 years, and the interview transcripts read for traces of discourses formative in shaping their response to the new course. I identified three discourses: Leavisite and New Critical formations of the subject Literature; charismatic pedagogy; and critical theory, which was embodied in the new subject's study design. These 3 discourses, together with the traditions and culture of the school, form the framework for analysis of the interviews. The paper explores ways in which the teachers' positioning within this mix of discourses and settings variously supported or undermined their preparedness to accept new configurations of the subject Literature as well as the implications of curriculum change not just for constructions of the subject but also for teacher subjectivity.

The structure of the perceived sociocultural influences on body image and body change questionnaire

This article is concerned with the development and evaluation of the Perceived Sociocultural Influences on Body Image and Body Change Questionnaire. The scale was designed to assess the perceived nature of feedback received from mother, father, best male friend, and best female friend to gain weight, lose weight, and increase muscle tone. The perceived feedback from the media on each of these areas also was assessed. Exploratory factor analysis was conducted with 240 adolescent boys (mean age = 13.83 years) and 204 adolescent girls (mean age = 13.70 years). A 3-factor structure was found for the 4 scales that related to perceived feedback from mother, father, best male friend, and best female friend. Feedback on muscle tone loaded with both weight loss and weight gain. The three factors related to (a) general feedback; (b) encourage, tease, and modeling to gain weight and increase muscle tone, and (c) encourage, tease, and modeling to lose weight and increase muscle tone. The factor structure and the items that made up these factors were the same for both boys and girls for each of the 4 scales. The Perceived Media Influences Scale formed 3 factors for girls. These factors related to gaining weight, losing weight, and increasing muscle tone. For boys, the same 9 items formed a single factor. The same items were retained for boys and girls. A confirmatory factor analysis with 822 adolescents (382 boys, mean age = 14.02 years; 440 girls, mean age = 13.82 years) confirmed the previously described factor structure. These results demonstrate that the Perceived Sociocultural Influences on Body Image and Body Change Questionnaire is able to assess body image and body change strategies that are relevant for both boys and girls.

Body image and body change techniques among young adolescent boys

The aim of the present study was to examine the level of body image disturbance among adolescent boys and to determine how body image disturbance was related to body change techniques. Twenty boys from year 7 (mean age = 12.55 years, SD = 0.61) and 20 boys from year 9 (mean age = 14.85 years, SD = 0.59) were interviewed individually about their body image and body change strategies. The boys were questioned about the importance and their satisfaction with their weight, body size, body shape, muscle tone and parts of their body and the frequency with which they used the following techniques: eating less to lose weight, eating more to gain weight, and exercise to change body size, shape or muscle tone. The results demonstrated that of those boys who wanted to change their body (50 per cent), 12 wanted to lose weight and eight wanted to gain weight. The most frequent strategy used to change body size or shape was exercise, rather than changing eating patterns. Year 7 boys were more satisfied with their weight than year 9 boys, and boys with a larger body mass index (BMI) were less satisfied with their muscle tone and more likely to change their eating habits to decrease their body size or shape than boys with a smaller BMI. The implications of these findings for obtaining a better understanding of how male body image and body change strategies are different from girls are discussed.

A biopsychosocial model for understanding body image and body change strategies among children

The present study was designed to assess the role of biopsychosocial factors in understanding body image concerns and cognitions and behaviors related to losing weight or increasing muscles among 507 children (270 girls and 237 boys) aged between 8 and 11 years. Biological, psychological, and sociocultural factors have been found to be relevant in understanding the development of body image concerns and weight loss strategies among children. However, these factors have not been examined together in a single study; thus, the relative influence of each factors and how these factors may interact is not known. In the current study, body mass index (BMI) was found to be a good indicator of girls' and boys' body dissatisfaction, while the main indicator of children's body change strategies was perceived pressure from parents, peers, and the media. Overall, there were more similarities than differences between girls and boys. The age between 8 and 11 years is a significant period to commence studying body image concerns and body change strategies, as it can be used to help us understand the emergence of gender differences in children's weight and muscle concerns.

Sociocultural influences on body image concerns and body change strategies among Indigenous and Non-Indigenous Australian adolescent girls and boys

Sociocultural messages about the ideal body build have been studied predominantlyamong White adolescent girls. In the current study we examined the relationships between perceived sociocultural influences, body image concerns, and body change strategies among 47 (22 boys and 25 girls) Indigenous Australian adolescents. These relationships were compared to those from 47 non-Indigenous adolescents (predominantly from an Anglo-Saxon background), who were matched on gender, age, and school grade. Overall, the sociocultural influences were found to be associated with body image concerns and body change strategies among both cultural groups. The only exception was that the sociocultural influences were not associated with the Indigenous girls levels of body dissatisfaction or body image importance. These findings are discussed in relation to past studies of White and Black girls.

Feminists re-reading Bourdieu: old debates and new questions about gender habitus and gender change

There is a revival of interest in Bourdieu's work and this article examines dominant trends within feminist re-engagements. It considers the insights into gender identity afforded by ‘habitus’ and ‘social field’, distinguishing between analyses of 'gender habitus', and the potential of habitus and social field for feminist analysis of change. Feminist responses to Bourdieu continue to be divided on the extent to which social field structure determines habitus, and there is a tendency to represent the relationship as too seamless and coherent. Drawing on debates within recent feminist sociology, notably the work of Lois McNay and Lisa Adkins, this article argues instead for greater acknowledgement of the instability of gender norms and the contradictory effects of crossing different social fields. A feminist rethinking of the relationship between gender change, habitus and social field is suggested, which arises from a more contextual analysis of the varying degrees of correspondence between habitus and field. This addresses the co-existence of change and continuity in gender relations and identities, and aims to move such debates beyond questions of either freedom or reproduction.

Socioeconomic status and weight change in adults: a review

In developed countries, obesity is inversely associated with socioeconomic status (SES) among women, and less consistently among men; whereas, in developing countries, the association is direct. However, the relationship of SES to weight change over time is unknown. This relationship was the focus of the present literature review. It was hypothesized that, compared with persons of higher SES, persons of low SES would show greater weight gain or risk of weight gain over time. A search of electronic databases identified 34 relevant articles from developed countries reporting on studies that assessed the relationship of various measures of SES with weight change over time in adults (there were too few papers from developing countries (n=1) to include). Results of the methodologically strongest studies (those which obtained objectively measured adiposity data and used a follow-up period of 4 years or more) showed that, among non-black samples, there were relatively consistent inverse associations between occupation and weight gain for men and women. When SES was assessed using education, evidence was slightly less consistent, but still provided some support for the hypothesized relationship. However, when income was used as the indicator of SES, findings were inconsistent, although there were fewer studies available. There was little support for a relationship between SES and weight gain for black samples. In the context of the worldwide epidemic of obesity, these findings suggest that in developed countries, weight gain prevention efforts might best be focused on those who are most socioeconomically disadvantaged, particularly those in lower status occupations.

Sociocultural influences on adolescent boys' body image and body change strategies

Society provides messages about how people should ideally look and previous research has indicated these messages, both the actual messages provided and the perception of the message, influence body image. Research into male body image has shown males are concerned with having a lean and muscular body and as such, may want to decrease fat and increase their muscles. This paper explored the influence of a range of messages from parents, peers, and the media on a number of different measures of 362 adolescent boys’ body image and body change strategies. Specifically, messages about shape, food, exercise, losing weight and increasing muscles were explored in relation to satisfaction with weight and muscles, and the use of strategies to decrease weight and increase muscles. The findings indicated that parental messages were the strongest influence on body image and that parents, the media, and to a lesser extent messages from male friends were the strongest predictors of body change strategies.

Reinforcement sensitivity theory (RST) and body change behaviour in males

According to the unrevised Reinforcement Sensitivity Theory two motivational systems shape personality: a behavioural approach system (BAS) that determines sensitivity to rewards, and a behavioural inhibition system (BIS) that determines sensitivity to punishments. The role of reinforcement sensitivity in body change behaviour in males was explored with a non-clinical sample of 120 men aged 18–40 years. Self-reported symptoms of unhealthy weight loss (weight preoccupation, fasting, bingeing/purging) and body development (muscle/size preoccupation, obligatory exercise, use of chemical supplements) were regressed on measures of BAS and BIS sensitivity. Significant relationships were observed between BAS sensitivity and body development, and between BIS sensitivity and weight loss. These relationships were mediated by internalization of the athletic/muscular ideal, body comparisons, the importance of achieving one’s ideal or ‘best possible’ body (in the case of BAS but not BIS), and body dissatisfaction (in the case of BIS but not BAS). These results support the proposition that body development in males is influenced by sensitivity to rewards associated with achieving a certain body shape, and that weight loss is influenced by sensitivity to punishments associated with possessing an unsatisfactory body shape.