Study of structural changes of pumpkin tissue before and after mechanical loading

The texture of agricultural crops changes during harvesting, post harvesting and processing stages due to different loading processes. There are different source of loading that deform agricultural crop tissues and these include impact, compression, and tension. Scanning Electron Microscope (SEM) method is a common way of analysing cellular changes of materials before and after these loading operations. This paper examines the structural changes of pumpkin peel and flesh tissues under mechanical loading. Compression and indentation tests were performed on peel and flesh samples. Samples structure were then fixed and dehydrated in order to capture the cellular changes under SEM. The results were compared with the images of normal peel and flesh tissues. The findings suggest that normal flesh tissue had bigger size cells, while the cellular arrangement of peel was smaller. Structural damage was clearly observed in tissue structure after compression and indentation. However, the damages that resulted from the flat end indenter was much more severe than that from the spherical end indenter and compression test. An integrated deformed tissue layer was observed in compressed tissue, while the indentation tests shaped a deformed area under the indenter and left the rest of the tissue unharmed. There was an obvious broken layer of cells on the walls of the hole after the flat end indentations, whereas the spherical indenter created a squashed layer all around the hole. Furthermore, the influence of loading was lower on peel samples in comparison with the flesh samples. The experiments have shown that the rate of damage on tissue under constant rate of loading is highly dependent on the shape of equipment. This fact and observed structural changes after loading underline the significance of deigning post harvesting equipments to reduce the rate of damage on agricultural crop tissues.

Post-glacial sea-level changes around the Australian margin : a review

It has been known since Rhodes Fairbridge’s first attempt to establish a global pattern of Holocene sea-level change by combining evidence from Western Australia and from sites in the northern hemisphere that the details of sea-level history since the Last Glacial Maximum vary considerably across the globe. The Australian region is relatively stable tectonically and is situated in the ‘far-field’ of former ice sheets. It therefore preserves important records of post-glacial sea levels that are less complicated by neotectonics or glacio-isostatic adjustments. Accordingly, the relative sea-level record of this region is dominantly one of glacio-eustatic (ice equivalent) sea-level changes. The broader Australasian region has provided critical information on the nature of post-glacial sea level, including the termination of the Last Glacial Maximum when sea level was approximately 125 m lower than present around 21,000–19,000 years BP, and insights into meltwater pulse 1A between 14,600 and 14,300 cal. yr BP. Although most parts of the Australian continent reveals a high degree of tectonic stability, research conducted since the 1970s has shown that the timing and elevation of a Holocene highstand varies systematically around its margin. This is attributed primarily to variations in the timing of the response of the ocean basins and shallow continental shelves to the increased ocean volumes following ice-melt, including a process known as ocean siphoning (i.e. glacio-hydro-isostatic adjustment processes). Several seminal studies in the early 1980s produced important data sets from the Australasian region that have provided a solid foundation for more recent palaeo-sea-level research. This review revisits these key studies emphasising their continuing influence on Quaternary research and incorporates relatively recent investigations to interpret the nature of post-glacial sea-level change around Australia. These include a synthesis of research from the Northern Territory, Queensland, New South Wales, South Australia and Western Australia. A focus of these more recent studies has been the re-examination of: (1) the accuracy and reliability of different proxy sea-level indicators; (2) the rate and nature of post-glacial sea-level rise; (3) the evidence for timing, elevation, and duration of mid-Holocene highstands; and, (4) the notion of mid- to late Holocene sea-level oscillations, and their basis. Based on this synthesis of previous research, it is clear that estimates of past sea-surface elevation are a function of eustatic factors as well as morphodynamics of individual sites, the wide variety of proxy sea-level indicators used, their wide geographical range, and their indicative meaning. Some progress has been made in understanding the variability of the accuracy of proxy indicators in relation to their contemporary sea level, the inter-comparison of the variety of dating techniques used and the nuances of calibration of radiocarbon ages to sidereal years. These issues need to be thoroughly understood before proxy sea-level indicators can be incorporated into credible reconstructions of relative sea-level change at individual locations. Many of the issues, which challenged sea-level researchers in the latter part of the twentieth century, remain contentious today. Divergent opinions remain about: (1) exactly when sea level attained present levels following the most recent post-glacial marine transgression (PMT); (2) the elevation that sea-level reached during the Holocene sea-level highstand; (3) whether sea-level fell smoothly from a metre or more above its present level following the PMT; (4) whether sea level remained at these highstand levels for a considerable period before falling to its present position; or (5) whether it underwent a series of moderate oscillations during the Holocene highstand.

Career-path analysis using optimal matching and self-organizing maps

This paper is devoted to the analysis of career paths and employability. The state-of-the-art on this topic is rather poor in methodologies. Some authors propose distances well adapted to the data, but are limiting their analysis to hierarchical clustering. Other authors apply sophisticated methods, but only after paying the price of transforming the categorical data into continuous, via a factorial analysis. The latter approach has an important drawback since it makes a linear assumption on the data. We propose a new methodology, inspired from biology and adapted to career paths, combining optimal matching and self-organizing maps. A complete study on real-life data will illustrate our proposal.

Susceptibility of the critical structural components of railway bridges to the changes in train speed

Modern trains with different axle configurations, speeds and loads are used in railway networks. As a result, one of the most important questions of the mangers involved in bridge managements systems (BMS) is how these changes affect the structural behavior of the critical components of the railway bridges. Although researchers have conducted, many investigations on the dynamic effects of the moving loads on bridges, the influence of the changes in the speed of the train on the demand by capacity ratios of the different critical components of the bridge have not yet been properly studied. This study is important, because different components with different capacities and roles for carrying loads in the structure may be affected differently. To investigate the above phenomenon in this research, a structural model of a simply supported bridge is developed. It will be verified that the dynamic behavior of this bridge is similar to a group of railway bridges in Australia. Demand by capacity ratios of the critical components of the bridge, when it is subjected to a train load with different speeds will be calculated. The results show that the effect of increase or decrease of speed should not be underestimated. The outcome is very significant as it is contrary to what is currently expected, i.e. by reducing the speed of the train, the demand by capacity ratio of components may increase and make the bridge unsafe for carrying live load.

In situ observation of structural changes in polycrystalline silver catalysts by environmental scanning electron microscopy

Morphology changes induced in polycrystalline silver catalysts as a result of heating in either oxygen, water or oxygen-methanol atmospheres have been investigated by environmental scanning electron microscopy (ESEM), FT-Raman spectroscopy and temperature programmed desorption (TPD). The silver catalyst of interest consisted of two distinct particle types, one of which contained a significant concentration of sub-surface hydroxy species (in addition to surface adsorbed atomic oxygen). Heating the sample to 663 K resulted in the production of 'pin-holes' in the silver structure as a consequence of near-surface explosions caused by sub-surface hydroxy recombination. Furthermore, 'pin-holes' were predominantly found in the vicinity of surface defects, such as platelets and edge structures. Reaction between methanol and oxygen also resulted in the formation of 'pin-holes' in the silver surface, which were inherently associated with the catalytic process. A reaction mechanism is suggested that involves the interaction of methanol with sub-surface oxygen species to form sub-surface hydroxy groups. The sub-surface hydroxy species subsequently erupt through the silver surface to again produce 'pin-holes'.

Thyroxine and reserpine-induced changes in metabolic profiles of rat urine and the therapeutic effect of Liu Wei Di Huang Wan detected by UPLC-HDMS

The promise of metabonomics, a new "omics" technique, to validate Chinese medicines and the compatibility of Chinese formulas has been appreciated. The present study was undertaken to explore the excretion pattern of low molecular mass metabolites in the male Wistar-derived rat model of kidney yin deficiency induced with thyroxine and reserpine as well as the therapeutic effect of Liu Wei Di Huang Wan (LW) and its separated prescriptions, a classic traditional Chinese medicine formula for treating kidney yin deficiency in China. The study utilized ultra-performance liquid chromatography/electrospray ionization synapt high definition mass spectrometry (UPLC/ESI-SYNAPT-HDMS) in both negative and positive electrospray ionization (ESI). At the same time, blood biochemistry was examined to identify specific changes in the kidney yin deficiency. Distinct changes in the pattern of metabolites, as a result of daily administration of thyroxine and reserpine, were observed by UPLC-HDMS combined with a principal component analysis (PCA). The changes in metabolic profiling were restored to their baseline values after treatment with LW according to the PCA score plots. Altogether, the current metabonomic approach based on UPLC-HDMS and orthogonal projection to latent structures discriminate analysis (OPLS-DA) indicated 20 ions (14 in the negative mode, 8 in the positive mode, and 2 in both) as "differentiating metabolites".

Optical data encryption using time-dependent dynamics of refractive index changes in LiNbO3

We present a method for optical encryption of information, based on the time-dependent dynamics of writing and erasure of refractive index changes in a bulk lithium niobate medium. Information is written into the photorefractive crystal with a spatially amplitude modulated laser beam which when overexposed significantly degrades the stored data making it unrecognizable. We show that the degradation can be reversed and that a one-to-one relationship exists between the degradation and recovery rates. It is shown that this simple relationship can be used to determine the erasure time required for decrypting the scrambled index patterns. In addition, this method could be used as a straightforward general technique for determining characteristic writing and erasure rates in photorefractive media.

Age-related changes in cardiac adenosine receptor expression

Adenosine is an important cardioprotective agent that works via several adenosine receptor (ADOR) subtypes to regulate cardiovascular activity. It is well established that functional responses to adenosine decline with age. What is unclear, though, is whether these changes occur at the receptor, second messenger or translational level. In this study we determined the effect of age on cardiac adenosine receptor expression using the housekeeping gene 18S rRNA versus the adenosine A2B receptor gene as internal controls. Absolute quantification showed that no age-related changes occurred in the expression of 18S rRNA or adenosine A2B receptor internal control genes. Subsequently, relative analysis of the adenosine receptor subtypes using 18S rRNA found a significant age-related reduction in the expression of the adenosine A1 receptor (5.5-fold), with no changes in the expression of the adenosine A2A, A2B and A3 receptors. When using the expression of the adenosine A2B receptor as the internal control gene, a significant down regulation of both the adenosine A1 (5.4-fold) and A2A (2.2-fold) receptors with no change in the expression of adenosine A3 receptor was found. Therefore, the high level of expression of the 18S rRNA housekeeping gene was found to mask a significant change in expression of the adenosine A2A receptor with age. Ultimately, these findings show an age-related reduction in adenosine A1 and A2A receptor expression in rat heart.

Changes in health profiles of participants in an Australian police department’s Wellness program

Background: Little is known about the health effects of worksite wellness programs on police department staff. Objective: To examine 1-2 year changes in health profiles of participants in the Queensland Police Service’s wellness program. Methods: Participants underwent yearly physical assessments. Health profile data collected during assessments from 2008 to 2012 were included in the analysis. Data Analysis: Repeated-measures ANOVA was used for continuous outcome variables, related-samples Wilcoxon Signed Rank test for non-normally continuous variables, and McNemar’s test for binary variables. Results: Significant changes in physical measures included decreases in waist circumference and percent body fat, and increases in cardiorespiratory fitness and flexibility (p<0.01). Changes in serum cholesterol, haemoglobin, total cholesterol ratios, HDL, LDL and Triglyceride levels were also significant (p<0.01). Conclusion: Participants’ health profiles mostly improved between cycles although most changes were not clinically significant. As this evaluation used a single-group pre-test post-test design, it provides initial indications that wellness programs can benefit staff in police departments.

Quantitative and qualitative changes in gene expression patterns characterize the activity of plaques in multiple sclerosis

Multiple sclerosis (MS) is a complex autoimmune disorder of the CNS with both genetic and environmental contributing factors. Clinical symptoms are broadly characterized by initial onset, and progressive debilitating neurological impairment. In this study, RNA from MS chronic active and MS acute lesions was extracted, and compared with patient matched normal white matter by fluorescent cDNA microarray hybridization analysis. This resulted in the identification of 139 genes that were differentially regulated in MS plaque tissue compared to normal tissue. Of these, 69 genes showed a common pattern of expression in the chronic active and acute plaque tissues investigated (Pvalue<0.0001, ρ=0.73, by Spearman's ρ analysis); while 70 transcripts were uniquely differentially expressed (≥1.5-fold) in either acute or chronic active tissues. These results included known markers of MS such as the myelin basic protein (MBP) and glutathione S-transferase (GST) M1, nerve growth factors, such as nerve injury-induced protein 1 (NINJ1), X-ray and excision DNA repair factors (XRCC9 and ERCC5) and X-linked genes such as the ribosomal protein, RPS4X. Primers were then designed for seven array-selected genes, including transferrin (TF), superoxide dismutase 1 (SOD1), glutathione peroxidase 1 (GPX1), GSTP1, crystallin, alpha-B (CRYAB), phosphomannomutase 1 (PMM1) and tubulin β-5 (TBB5), and real time quantitative (Q)-PCR analysis was performed. The results of comparative Q-PCR analysis correlated significantly with those obtained by array analysis (r=0.75, Pvalue<0.01, by Pearson's bivariate correlation). Both chronic active and acute plaques shared the majority of factors identified suggesting that quantitative, rather than gross qualitative differences in gene expression pattern may define the progression from acute to chronic active plaques in MS.

Phenotypic changes in artemisinin-resistant plasmodium falciparum lines in vitro: evidence for decreased sensitivity to dormancy and growth inhibition

The appearance of Plasmodium falciparum parasites with decreased in vivo sensitivity but no measurable in vitro resistance to artemisinin has raised the urgent need to characterize the artemisinin resistance phenotype. Changes in the temporary growth arrest (dormancy) profile of parasites may be one aspect of this phenotype. In this study, we investigated the link between dormancy and resistance, using artelinic acid (AL)-resistant parasites. Our results demonstrate that the AL resistance phenotype has (i) decreased sensitivity of mature-stage parasites, (ii) decreased sensitivity of the ring stage to the induction of dormancy, and (iii) a faster recovery from dormancy.

The duration of Chlamydia muridarum genital tract infection and associated chronic pathological changes are reduced in IL-17 knockout mice but protection is not increased further by immunization

IL-17 is believed to be important for protection against extracellular pathogens, where clearance is dependent on neutrophil recruitment and local activation of epithelial cell defences. However, the role of IL-17 in protection against intracellular pathogens such as Chlamydia is less clear. We have compared (i) the course of natural genital tract C. muridarum infection, (ii) the development of oviduct pathology and (iii) the development of vaccine-induced immunity against infection in wild type (WT) BALB/c and IL-17 knockout mice (IL-17-/-) to determine if IL-17-mediated immunity is implicated in the development of infection-induced pathology and/or protection. Both the magnitude and duration of genital infection was significantly reduced in IL-17-/- mice compared to BALB/c. Similarly, hydrosalpinx was also greatly reduced in IL-17-/- mice and this correlated with reduced neutrophil and macrophage infiltration of oviduct tissues. Matrix metalloproteinase (MMP) 9 and MMP2 were increased in WT oviducts compared to IL-17-/- animals at day 7 post-infection. In contrast, oviducts from IL-17-/- mice contained higher MMP9 and MMP2 at day 21. Infection also elicited higher levels of Chlamydia-neutralizing antibody in serum of IL-17-/- mice than WT mice. Following intranasal immunization with C. muridarum Major Outer Membrane Protein (MOMP) and cholera toxin plus CpG adjuvants, significantly higher levels of chlamydial MOMP-specific IgG and IgA were found in serum and vaginal washes of IL-17-/- mice. T cell proliferation and IFNγ production by splenocytes was greater in WT animals following in vitro re-stimulation, however vaccination was only effective at reducing infection in WT, not IL-17-/- mice. Intranasal or transcutaneous immunization protected WT but not IL-17-/- mice against hydrosalpinx development. Our data show that in the absence of IL-17, the severity of C. muridarum genital infection and associated oviduct pathology are significantly attenuated, however neither infection or pathology can be reduced further by vaccination protocols that effectively protect WT mice.

Early career teacher attrition: A case study of independent Catholic girls' schools in Queensland

This research study sought to understand why so many early career teachers in an Australian Religious Institute education sector were leaving teaching. Previous studies on early career teacher attrition across all sectors were based on supply and demand theory, as well as contemporary career theory, and identified various factors such as remuneration, student behaviour and school resourcing as influencing factors. These Australian Religious Institute education sector schools take pride in their good standing. The schools in this sector have worked at addressing many of the factors associated with early career teacher attrition yet despite their efforts they are also experiencing attrition of their early career teachers. A case study of the Queensland independent Catholic girls' school sector explored firstly, the construct of being a teacher in these schools, and secondly, the sociocultural discourses giving rise to unique situations contributing to early career teachers making the decision to leave teaching. Eight early career teachers who had left the profession for which they had recently trained, and eight long standing teachers who were still employed in the sector were interviewed to yield a rich data set. The interviews were conducted within a theoretical framework of what it means to be a teacher by Graham and Phelps (2003) and pedagogic identity and pedagogic practice as noted by Bernstein (2000). The distributive rules and the evaluative rules (Bernstein, 2000) provided the analytical framework to confirm that particular discourses, together with the ways in which the early career teachers realised being a teacher, were important factors in the decision not to remain in teaching. It emerged that being a teacher in the Queensland independent Catholic girls' school sector was complex and demanding. Being a teacher required long hours of personal time to realise the demands of teaching, a situation which did not fare well with the early career teachers who struggled to balance the requirements of teaching with their own personal time. Furthermore, evidence was found that the schools had multifaceted sociocultural discourses that the early career teacher research participants struggled to understand. In contrast, long standing teachers had, through time, experience and observation, developed skills that allowed them to navigate these complex discourses and thus remain long term in the sector. Another finding revealed the considerable dichotomy in how the charism of the schools (the unique way Catholic institutions transmit the beliefs and teachings of the Catholic Church) unfolded for students and staff. While these schools transmit their charism effectively to the students, it is ineffectively transmitted to early career teachers. In contemporary times when a majority of teachers in Australia are moving into their 50s and large numbers are retiring or resigning, (Australian Government, 2011; Australian Government Department of Education, 2007b) it is important for the long term viability of the independent Catholic school sector to retain a stable staff. This study demonstrates that if Catholic schools want to retain their unique identity in the education community and sustain their unique charisms, then they must adopt positive practices to support early career teachers.

Understanding the impact of legislative changes on child car seating and restraint practices in regional Queensland

Road crashes contribute to a significant amount of child mortality and morbidity in Australia. In fact, passenger injuries contribute to the majority of child crash road trauma. A number of factors contribute to child injury and death in motor vehicles, including inappropriate seating position, inappropriate choice of restraint, and incorrect installation and use of child restraints. Prior to March 2010, child restraint legislation in Queensland only required children twelve months and younger to be seated in a properly adjusted and fastened child restraint. This legislation left older infants and young children potentially suboptimally protected. From March 2010, new legislation specified seating position and type of child restraint required, depending on the age of the child. This research was underpinned by the Health Belief Model (HBM), which explores health related behaviour, behaviour change, environmental factors influencing behaviour change (including legislative changes) and is flexible enough to be used in relation to parents' health practices for their children, rather than parent health directly. This thesis investigates the extent to which the changes to child restraint legislation have led parents in regional areas of Queensland to use appropriate restraint practices for their children and determines the extent to which the constructs of the HBM, parental perceptions, barriers and environmental factors contribute to the appropriateness of child seating and restraint use. Study One included three sets of observations taken in two regional cities of Queensland prior to the legislative amendment, during an educative period of six months, and after the enactment of the legislation. Each child's seating position and restraint type were recorded. Results showed that the proportion of children observed occupying the front seat decreased by 15.6 per cent with the announcement the legislation. There was no decrease in front seat use at the enactment of the legislation. The proportion of children observed using dedicated child restraints increased by 8.8 per cent with the announcement of the legislation when there was one child in the vehicle. Further, there was a 10.1 per cent increase in the proportion of children observed using a seat belt that fit with the announcement when there was one child in the vehicle and with the enactment of the legislation regardless of the number of children in the vehicle (21.8 per cent for one child, 39.7 per cent for two children and 40.2 per cent for three or more children). Study Two comprised initial intercept interviews, later followed up by telephone, with parents with children aged eight years and younger at the announcement and telephone interviews at the enactment of the legislation in one regional city in Queensland. Parents reported their child restraint practices, and opinions, knowledge and understanding of the requirements of the new legislation. Parent responses were analysed in terms of the constructs in the HBM. When asked which seating position their child 'usually' used, parents reported child front seat use was nil (0.0 per cent) and did not change with the enactment of the legislative amendment. However, when parents were asked whether they allowed children to use the front seat at some point within the six months prior to the interview, reported child front seat use was 7 (5.4 per cent) children at T2 and 10 (9.6 per cent) at T3. Reported use of age-appropriate child restraints did not increase with the enactment of the legislation (p = 0.77, ns). Parents reported restraint practices were classed as either appropriate or inappropriate. Parents who reported appropriate restraint practices were those whose children were sitting in optimal restraints and seating positions for their age according to the requirements of the legislation. Parents who reported inappropriate restraint practices were those who had one or more children who were suboptimally restrained or seated for their age according to the requirements of the legislation. Neither parents' perceptions about their susceptibility of being in a crash nor the likelihood of severity of child injury if involved in a crash yielded significant differences in the appropriateness of reported parent restraint practices over time with the enactment of the legislation. A trend in the data suggested parents perceived a benefit to using appropriate restraint practices was to avoid fines and demerit points. Over 75 per cent of parents who agreed that child restraints provide better protection for children than an adult seat belt reported appropriately seating and restraining their children (2 (1) = 8.093, p<.05). The self-efficacy measure regarding parents' confidence in installing a child restraint showed a significant association with appropriate parental restraint practices (2 (1) = 7.036, p<.05). Results suggested that some parents may have misinterpreted the announcement of the legislative amendment as the announcement of the enforcement of the legislation instead. Some parents who correctly reported details of the legislation did not report appropriate child restraint practices. This finding shows that parents' knowledge of the legislative amendment does not necessarily have an impact on their behaviour to appropriately seat and restrain children. The results of these studies have important implications for road safety and the prevention of road-related injury and death to children in Queensland. Firstly, parents reported feeling unsure of how to install restraints, which suggests that there may be children travelling in restraints that have not been installed correctly, putting them at risk. Interventions to alert and encourage parents to seek advice when unsure about the correct installation of child restraints could be considered. Secondly, some parents in this study although they were using the most appropriate restraint for their children, reported using a type that was not the most appropriate restraint for the child's age according to the legislation. This suggests that intervention may be effective in helping parents make a more accurate choice of the most appropriate type of restraint to use with children, especially as the child ages and child restraint requirements change. Further research could be conducted to ascertain the most effective methods of informing and motivating parents to use the most appropriate restraints and seating positions for their children, as these results show a concerning disparity between reported restraint practices and those that were observed.

Middle schooling and scientific literacy : bringing the students to science

This study is about young adolescents' engagement in learning science. The middle years of schooling are critical in the development of students' interest and engagement with learning. Successful school experiences enhance dispositions towards a career related to those experiences. Poor experiences lead to negative attitudes and rejection of certain career pathways. At a time when students are becoming more aware, more independent and focused on peer relationships and social status, the high school environment in some circumstances offers more a content-centred curriculum that is less personally relevant to their lives than the social melee surrounding them. Science education can further exacerbate the situation by presenting abstract concepts that have limited contextual relevance and a seemingly difficult vocabulary that further alienates adolescents from the curriculum. In an attempt to reverse a perceived growing disinterest by students to science (Goodrum, Druhan & Abbs, 2011), a study was initiated based on a student-centred unit designed to enhance and sustain adolescent engagement in science. The premise of the study was that adolescent students are more responsive toward learning if they are given an appropriate learning environment that helps connect their learning with life beyond the school. The purpose of this study was to examine the experiences of young adolescents with the aim of transforming school learning in science into meaningful experiences that connected with their lives. Two areas were specifically canvassed and subsumed within the study to strengthen the design base. One area that of the middle schooling ideology, offered specific pedagogical approaches and a philosophical framework that could provide opportunities for reform. The other area, the construct of scientific literacy (OECD, 2007) as defined by Holbrook and Rannikmae, (2009) appeared to provide a sense of purpose for students to aim toward and value for becoming active citizens. The study reported here is a self-reflection of a teacher/researcher exploring practice and challenging existing approaches to the teaching of science in the middle years of schooling. The case study approach (Yin, 2003) was adopted to guide the design of the study. Over a 6-month period, the researcher, an experienced secondary-science teacher, designed, implemented and documented a range of student-centred pedagogical practices with a Year-7 secondary science class. Data for this case study included video recordings, journals, interviews and surveys of students. Both quantitative and qualitative data sources were employed in a partially mixed methods research approach (Leech & Onwuegbuzie, 2009) dominated by qualitative data with the concurrent collection of quantitative data to corroborate interpretations as a means of analysing and developing a model of the dynamic learning environment. The findings from the case study identified five propositions that became the basis for a model of a student-centred learning environment that was able to sustain student participation and thus engagement in science. The study suggested that adolescent student engagement can be promoted and sustained by providing a classroom climate that encourages and strengthens social interaction. Engagement in science can be enhanced by presenting developmentally appropriate challenges that require rigorous exploration of contextually relevant learning environments; supporting students to develop connections with a curriculum that aligns with their own experiences. By setting an environment empathetic to adolescent needs and understandings, students were able to actively explore phenomena collaboratively through developmentally appropriate experiences. A significant outcome of this study was the transformative experiences of an insider, the teacher as researcher, whose reflections provide an authentic model for reforming pedagogy. The model and theory presented became an adjunct to my repertoire for science teaching in the middle years of schooling. The study was rewarding in that it helped address a void in my understanding of middle years of schooling by prompting me to re-think the notion of adolescence in the context of the science classroom. This study is timely given the report "The Status and Quality of Year 11 and 12 Science in Australian Schools" (Goodrum, Druhan & Abbs, 2011) and national curricular changes that are being proposed for science (ACARA, 2009).