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Social semiotic discussions about the role played by representations in effective teaching and learning in areas such as physics have led to theoretical proposals that have a strong common thread: in order to acquire an appropriate understanding of a particular object of learning, access to the disciplinary relevance aspects in the representations used calls for the attainment of representational competence across a particular "critical constellation of systematically used semiotic resources (which are referred to as" modes, "see more on this later)." However, an affirming empirical investigation into the relationship between a particular object of learning and different representational formulations, particularly with large numbers of students, is missing in the literature, especially in the context of university-level physics education. To start to address, this research shortfall the positioning for this article is that such studies need to embrace the complexities of student thinking and application of knowledge. To achieve this, both factor and network analyses were used. Even though both approaches are grounded in different frameworks, for the task at hand, both approaches are useful for analyzing clustering dynamics within the responses of a large number of participants. Both also facilitate an exploration of how such clusters may relate to the semiotic resource formulation of a representation. The data were obtained from a questionnaire given to 1,368 students drawn from 12 universities across 7 countries. The questionnaire deals with the refraction of light in introductory-level physics and involves asking students to give their best prediction of the relative visual positioning of images and objects in different semiotically constituted situations. The results of both approaches revealed no one-to-one relationship between a particular representational formulation and a particular cluster of student responses. The factor analysis used correct answer responses to reveal clusters that brought to the fore three different complexity levels in relation to representation formulation. The network analysis used all responses (correct and incorrect) to reveal three structural patterns. What is evident from the results of both analyses is that they confirm two broad conclusions that have emerged from social semiotic explorations dealing with representations in relation to attempting to optimize teaching and learning. The first, which is linked to a facilitating-awareness perspective, is that any given disciplinary visual representation can be expected to evoke a dispersed set of knowledge structures, which is referred to as their "relevance structure." Thus, the network analysis results can be seen as presenting a unique starting point for studies aiming to identify such "relevance structure." The second broad conclusion is that disciplinary visual representation can and often does contain more "disciplinary-relevant aspects" than what may be directly visible in a given representation. These are referred to as the "appresent" aspects that need to become part of the total awareness needed by someone to constitute an intended meaning. The results of the factor analysis can then also be seen to be a way of capturing "all" the disciplinary-relevant aspects (both present and appresent). Educational implications are discussed.

This article illustrates a learning sequence from the Interdisciplinary Mathematics and Science (IMS) Learning project, connecting science and mathematics learning in the primary school. Exploring light and its properties involved a series of investigations conducted in Grades 4 and 5 across three classes in two schools in regional Victoria. The teachers implemented an inquiry-based pedagogical model to guide students' spatial reasoning by exploring angle, symmetry, rotation, 2D diagrams and 3D models in an investigation of light reflection, using multiple representations. Students developed ideas from a "maze challenge" used in their design of a periscope.

Technological developments allow students to access visual information from digital devices as small as phones or as large as whiteboards. Education technology research and policy typically address the software product, yet little research has focused on optimal viewing parameters or the impact it has on student users. Students with light sensitivity (migraine, concussion) potentially face a barrier with e-learning activities in the classroom. This review aimed to identify points of convergence and inconsistency across various literature sources containing guidelines for digital media use by students in schools. Inconsistencies were found between academic, manufacturer and school guidelines. Six parameters were identified for modification on behalf of students with light sensitivity relating to image colour, image flash frequency, duration of viewing, luminance and environmental lighting -- both natural and artificial. The findings highlight the need for revision of school policies regarding digital learning environments and awareness raising to support inclusive access and use by students with light sensitivity.

There is a growing interest in the value of teachers guiding students to generate their own representations to support conceptual learning in science and across complementary subjects such as mathematics. However, this approach to an interdisciplinary focus poses challenges for programme design and learning assessment. In this paper, we report on a 10-week study with a class of Year 5 students designed to (a) facilitate learning of key concepts in the topic of optics (e.g. reflection), and (b) make meaningful links between these concepts and relevant mathematical ones (e.g. symmetry and angles). Students were expected to construct, evaluate and refine representations to explain various experienced phenomena. We report on an assessment framework developed and applied to student work. Our findings indicate (a) some subject and interdisciplinary learning gains, and (b) specific challenges around designing this kind of programme, student learning assessment and teacher understanding to support this learning.

Diffraction is an important phenomenon in physics. This paper describes using a scanning electron microscope (SEM) to produce cross-sectional images of iridescent seashells. When seashell cross-sections are viewed in a SEM, regular structure is seen. Seashells are a good example of a biocomposite material and good natural objects for introducing students to composite materials.

An action research study was designed to evaluate the effectiveness of providing metacognitive support to enhance Year 9 students' metacognitive capabilities in order to better understand science concepts related to light, environmental health, ecosystems, genetics, ecology, atoms and the Periodic Table. The study was conducted over three years involving 35, 20 and 24 students in each year. The interventions included providing students with clearly stated focused outcomes about the relevant science concepts, engaging in collaborative group work, reading scientific texts and using concept mapping techniques. The data to evaluate the effectiveness of the metacognitive interventions were obtained from pre- and posttest results of the "Metacognitive Support Questionnaire" ("MSpQ"). The results showed gains in the "MSpQ."

STEM is about the integration of science, technology, engineering and mathematics. To teach STEM effectively, students need practical examples of subject integration. A good example is the use of an electron microscope in teaching physics and biology. An electron microscope is an instrument in which the operation depends on electromagnetism and quantum mechanics, in particular wave-particle duality. In teaching physics, an electron microscope can be used to measure the separation of repeated structures that give rise to interference phenomena. This paper describes the use a tabletop scanning electron microscope to teach physics and biology together through imaging butterfly wings. Students are able to identify structures with a spacing comparable to visible light on butterflies exhibiting structural colour and much larger spacing on wings without structural colour.

This paper describes the use of a tabletop electron microscope in teaching college level physics. The workings and use of an electron microscope encompass many aspects of science, technology, engineering and mathematics (STEM). A sequence of activities was constructed to compliment the instructional material in the physics course of the University of Queensland Foundation Year. A Hitachi TM4000 scanning electron microscope was used to obtain images to measure the track spacing of CD, DVD and Blu-ray discs. The nominal track spacings are 1.6 µm, 740nm and 320nm for CD, DVD and Blu-ray discs, respectively, comparable to the wavelength of visible light and therefore give rise to visible diffraction effects. The track spacing for a CD and DVD was measured using red, green and blue laser pointers with an accuracy well under 10%. The experiments described in this paper demonstrate how a scientific instrument such as a scanning electron microscope can be used to integrate the teaching of different STEM areas.

The decline in students' interest in science and technology is a major concern in the western world. One approach to reversing this decline is to introduce modern physics concepts much earlier in the school curriculum. We have used the context of the recent discoveries of gravitational waves to test the benefits of one-day interventions, in which students are introduced to the ongoing nature of scientific discovery, as well as the fundamental concepts of quantum physics and gravitation, which underpin these discoveries. Our innovative approach combines role-playing, model demonstrations, single photon interference and gravitational wave detection, plus simple experiments designed to emphasize the quantum interpretation of interference. We compare understanding and attitudes through pre and post testing on four age groups (school years 7, 8, 9 and 10), and compare results with those of longer interventions with Year 9. Results indicate that neither prior knowledge nor age are significant factors in student understanding of the core concepts of Einsteinian physics. However we find that the short interventions are insufficient to enable students to comprehend more derived concepts.

The Einstein-First project approaches the teaching of Einsteinian physics through the use of physical models and analogies. This paper presents an approach to the teaching of quantum physics which begins by emphasising the particle-nature of light through the use of toy projectiles to represent photons. This allows key concepts including the spacing between photons, and photon momentum to be introduced. This in-turn allows an intuitive understanding of the uncertainty principle. We present optical interference in the context of individual photons, using actual videos showing the development of images one at a time. This enables simple laser interference experiments to be interpreted through the statistical arrival of photons. The wave aspects of quantum phenomenon are interpreted in terms of the wavelike nature of the arrival probabilities. [For Part 1, see EJ1156587, and for Part 3, see EJ1156596.]

Nationally and internationally there have been calls for a focus on STEM (science, technology, engineering and mathematics) teaching and learning in schools to prepare students for the many future careers in the STEM fields. One way to do this is through engineering activities that provide opportunities for integrating STEM to solve problems using engineering design principles. Based on the Australian curriculum developed by the Australian Curriculum and Assessment Reporting Association (ACARA), the researchers designed an optical engineering activity for Year Five students (9-10 year olds) that was a culminating STEM activity in a unit of work focussing on light. The task required the application of mathematics, science and technology concepts to build an optical instrument that would enable students to see a hidden object or person. The study found that using an engineering design model that involved building, testing and re-designing, afforded students opportunities to demonstrate the application of core mathematics, science and technology concepts. This article describes firstly, the foundational work on light and optical engineering that preceded the engineering problem, and secondly, the engineering problem.

Simply stated, light is nature's way of transferring energy through space. Discussions of light usually refer to visible light, which is perceived by the human eye and is responsible for the sense of sight. We see however, only a small part of the light spectrum. Light connects us as we sit and tell yarns around camp fires. Yet, one in every four people in the world lives without electricity. To answer this world-wide deficit, the United Nations announced 2015 to be the International Year of Light and Light-based Technologies. This article presents a discussion of the basics of light, how it can be produced, how it travels, and how it can be both seen and unseen. With the help of technology, invisible light can reveal certain things that are normally hidden from our eyes in the form of microwaves or X-rays. Today, with new and improved light technologies--such as optical fibres, radio telescopes, and X-ray detectors--we can explore and connect the nations of the world like never before.

The Australian Curriculum: Science for Year 5 includes "recognising that the colour of an object depends on the properties of the object and the color of the light source". This article shows how much more can be done with color in the science laboratory. Activities include using a prism to explore white light, using a hand lens to examine a patch of color on a computer screen, seeing the effect of Benham's disc, and demonstrating how color afterimages are produced. Short lessons on chromatography, color from polarising filters, color in plants, and making a spectroscope are also described.

This paper reports on the nature of the conceptual understandings developed by Year 12 Victorian Certificate of Education (VCE) physics students as they made the transition from the essentially deterministic notions of classical physics, to interpretations characteristic of quantum theory. The research findings revealed the fact that the understandings achieved by students were not always scientifically valid, or necessarily consistent with what had been taught in class. Analysis of the research data also revealed the fact that some of the students' mental constructions were in fact quite complex--often making use of a range of visual models and mathematical theories to make sense of quantum reality. This area of research is of significant importance given the fact that quantum theory plays such a central role in our understanding of science and technology.

A method is described for building a cost effective digital circuit capable of monitoring the solar radiation incident upon a remote solar cell. The circuit is built in two sections, the first, digitises the analogue voltage produced by the solar cell at a remote location and transmits the received signal to the second receiver circuit which relays the information to a computer for storage. The activity introduces students to simple programming techniques required to communicate with a computer serial interface, and to analyse binary signals for accurate interpretation of the induced solar cell voltage resulting from exposure to sunlight. The activity can be extended by investigating the influence of solar cell tilt angle with respect to solar position, studying the effect of seasonal solar altitude differences and noting the effect of cloud on the radiation received. The completed project provides schools with their own solar radiation monitoring station which can be used for future studies of weather and climate. (Contains 6 figures.)

"Glimpses of Science" is the outcome of collaboration between the University of New South Wales and four primary schools in the Sydney metropolitan region. A prototype kit on the topic of sound was developed and demonstrated by the team. This kit formed the basis for further science activities to be designed and produced in conjunction with the teachers. Students formed small groups to conduct hands-on activities that investigated the topics of sound, pendulums, light and energy. Instructional multimedia was used to illustrate certain aspects of the hands-on activities and also as a prompt to generate class discussion. Student and teacher feedback was positive. The resources are available on the web. (Contains 1 table and 2 figures.)

A technique for using highlighter ink as an ultraviolet dosimeter has been developed for use by secondary school students. The technique requires the students to measure the percentage of colour fading in ink drawn onto strips of paper that have been exposed to sunlight, which can be calibrated to measurements of the ultraviolet irradiance using an inexpensive and readily available pocket-sized meter. The concepts introduced in the article provide students with simple computer image processing and scientific measurement skills that enhance understanding of the ultraviolet environment. The methods presented in this article allow school students to make accurate measurements of personal ultraviolet exposure using self made and calibrated ultraviolet dosimeters which until now have not been readily available to schools. (Contains 2 tables and 3 figures.)

In this article I explain why I wrote the set of teaching notes on Atomic Absorption Spectroscopy (AAS) and why they look the way they do. The notes were intended as a student reference to question, highlight and write over as much as they wish during an initial practical demonstration of the threshold concept being introduced, in this case inferring the existence of quantized electron energy levels in atoms from class room observations. That is why the notes commence with an overview of how a handheld spectroscope works followed by how they are used for analysing emission spectroscopy observations. The notes decode the noun phrase "Atomic Absorption Spectroscopy" into its individual sequenced components by defining Light Spectra [right arrow] Spectroscopy [right arrow] Emission Spectroscopy [right arrow] Atomic Emission Spectroscopy (AES) [right arrow] Atomic Absorption Spectroscopy. There is every expectation that the teacher delivering this introduction has provided a class set of hand held spectroscopes to the students and a variety of demonstration emission sources such as hollow cathode lamps for mono atomic helium and neon plus a sodium vapour lamp. This concrete experience can now be developed into abstract knowledge and analytical applications in line with the South Australian Stage 2 Chemistry Curriculum Statement (CS) requiring students to understand the principles of AES and AAS. It is also an explicit departure from the more traditional secondary school method of presenting electron energy levels in atoms as a form of ritualized knowledge. The teaching notes that follow show how practical inquiry in the secondary school class room can remain the foundation of scientific method and learning with even the most troublesome of knowledge, such as electron energy levels in atoms. (Contains 2 figures.)

Context: Avena sterilis subsp. ludoviciana (wild oats) is one of the major winter weeds of the Northern Grains Region of Australia. The abundance of this weed increased dramatically after the adoption of no-tillage conservation agriculture (NTCA). However, information is lacking on the germination characteristics of the two types of seed (i.e. primary and secondary) that it produces. Aims: We aimed to determine the light and temperature requirements for germination and the time to germination of primary and secondary seeds of A. ludoviciana , in order to find ways to manage this weed effectively under NTCA systems. Methods: Primary and secondary seeds and caryopses from two southern and two northern biotypes were exposed to a range of temperature and light regimes in the glasshouse, and germination was assessed. Key results: All biotypes had ∼25% higher germination from primary than secondary seeds. Removing the hull increased caryopsis germination by ∼70%. The use of a light/dark photoperiod stimulated germination of both types of seed and caryopses compared with continuous darkness. Based on data for caryopses, 7°C and 9°C were found to be optimal germination temperatures for southern and northern biotypes, respectively. At optimum germination temperature, primary caryopses germinated 7–20 days earlier than secondary caryopses. In addition, a light/dark environment resulted in germination 2–6 days earlier than continuous darkness. Conclusions: In the Northern Grains Region, seeds retained on or close to the soil surface (i.e. in NTCA systems) can undergo maximum germination during May–June (late autumn–winter), when long-term average temperatures match optimum germination temperatures. This coincides with winter crop plantings. Implications: The seasonal timing of germination and the difference in germination timing between primary and secondary seeds, which help to stagger emergence of this weed, are major issues that need to be addressed in NTCA systems. Wild oats (Avena sterilis subsp. ludoviciana) is one of the major winter weeds of Australia, and has increased in abundance after the adoption of conservation agriculture. This germination study found that maximum emergence can occur during winter crop planting, and can be staggered because of difference in timing of germination between primary and secondary seeds produced by this weed. These characteristics makes A. sterilis difficult to control in conservation agriculture. [ABSTRACT FROM AUTHOR]

Background: Australia has one of the highest skin cancer rates in the world. 'SunSmart' is a multi-component, internationally recognised community-wide skin cancer prevention program implemented in Melbourne, Australia, since summer 1988-1989. Following recent reductions in melanoma rates among younger Australian cohorts, the extent of behaviour change and the potential contribution of prevention programs to this decline in melanoma rates are of interest. Sun protection is a multifaceted behaviour. Measures previously applied to monitor change over time in preventive behaviour for this population focused on individual behaviours. The omission of multiple behaviours that reduce exposure to ultraviolet radiation (UV) may have led to underestimates of behaviour change, meriting further analysis of long-term trends to contribute to this debate.Methods and Findings: A population-based survey was conducted in Melbourne in the summer before SunSmart commenced (1987-1988) and across summers in 3 subsequent decades (1988-2017). During summer months, residents (14-69 years) were recruited to cross-sectional weekly telephone interviews assessing their tanning attitudes, sun protection behaviour, and sunburn incidence on the weekend prior to interview. Quotas were used to ensure the sample was proportional to the population by age and sex, while younger respondents were oversampled in some years. The majority of the respondents reported their skin was susceptible to sunburn. Changes in sun protection behaviour were analysed for N = 13,285 respondents in multivariable models, cumulating surveys within decades (1987-1988: N = 1,655; 1990s: N = 5,258; 2000s: N = 3,385; 2010s: N = 2,987) and adjusting for relevant ambient weather conditions and UV levels on weekend dates. We analysed specific and composite behaviours including a novel analysis of the use of maximal sun protection, which considered those people who stayed indoors during peak UV hours together with those people well-protected when outdoors. From a low base, use of sun protection increased rapidly in the decade after SunSmart commenced. The odds of use of at least 1 sun protection behaviours on summer weekends was 3 times higher in the 1990s than pre-SunSmart (adjusted odds ratio [AOR] 3.04, 95% CI 2.52-3.68, p < 0.001). There was a smaller increase in use of maximal sun protection including shade (AOR = 1.68, 95% CI 1.44-1.97, p < 0.001). These improvements were sustained into the 2000s and continued to increase in the 2010s. Inferences about program effects are limited by the self-reported data, the absence of a control population, the cross-sectional study design, and the fact that the survey was not conducted in all years. Other potential confounders may include increasing educational attainment among respondents over time and exposure to other campaigns such as tobacco and obesity prevention.Conclusions: With an estimated 20-year lag between sun exposure and melanoma incidence, our findings are consistent with SunSmart having contributed to the reduction in melanoma among younger cohorts. [ABSTRACT FROM AUTHOR]

Understanding how species' traits can shape winners and losers of environmental change can help resolve drivers of current community composition patterns and predict future drivers. Sedimentation is one of the main environmental stressors shaping coastal marine communities and tolerance of high sedimentation rates (e.g. via morphological variation) may allow for competitive dominance. In New South Wales, Australia, the abundance and range of the native green macroalga Caulerpa filiformis have increased over recent decades, apparently associated with sediment disturbance. We used field measurements to test hypotheses about morphological variability in C. filiformis in relation to local- and large-scale environmental variation in water depth, sediment cover and latitude. Using a lab experiment, we tested hypotheses about survival and morphological change under different sedimentation regimes. In the field, C. filiformis fronds were more elongated and less branched when a sediment veneer is present and when water depth increased (i.e. reduced light). At larger spatial scales, frond length and width decreased with increased latitude, but latitude was less important in explaining the variation C. filiformis ' length than were depth or sedimentation. Our lab experiment showed a high tolerance to sedimentation, aided by increased investment in vertical growth. This study shows that rapid morphological plasticity is a likely key attribute of the spreading native macroalga C. filiformis. We argue that having a broad environmental tolerance is key to define a species success under environmental change. • C. filiformis morphology changes with both local- and large-scale environmental variation. • The macroalga is highly tolerant to long-term sedimentation, irrespective of rate or frequency. • Sedimentation tolerance appears aided by rapid morphological adaptation. • Morphological adaptation to sediment burial is similar to changes observed with increasing water depth (and reduced light). • The macroalga's spread is likely linked to indirect rather than direct benefits of sedimentation. [ABSTRACT FROM AUTHOR]

Background: Causes for a seasonal impact on admissions for mania remain to be clarified. We examined the impact of photoperiod, rate of change of photoperiod and hours of sunshine on admissions over an extended period.Methods: Monthly admission data to NSW psychiatric hospitals for more than twenty thousand patients admitted for mania over a fifteen-year period were correlated with photoperiod and sunshine changes.Results: While the peak in admissions occurred in spring, the shift in admissions being under-represented to being precipitously over-represented corresponded with the photoperiod commencing to increase in winter (i.e. July). Analyses identified rate of change in photoperiod as somewhat more influential than change in photoperiod and with hours of sunshine not making a distinctive contribution. Immediate and delayed impacts of rate of change as well as change in photoperiod across the whole year accounted for a distinctive 20% of the variance in hospital admissions.Limitations: Validity of mania diagnoses cannot be established from the data set, admission data were obtained from across the state while meteorological data were obtained from the capital city, lag periods between onset of a mania and hospitalization (while identified) would impact on associations, social factors were not included and study associations do not imply causality.Conclusions: The lack of a strong year-long correlation may reflect photoperiod changes being only a weak causal factor or that its influence may be through a strong impact phase after the winter solstice and with the spring peaking of admissions reflecting secondary photoperiod or other influences. [ABSTRACT FROM AUTHOR]

The number of people receiving maintenance haemodialysis (HD) in Australia has increased from 251 per million population in 1995 to 515 per million population in 2014. In-centre night haemodialysis (INHD) was introduced in one unit as a response to the rising numbers of people requiring HD. This study was designed as a quality project to evaluate a new service and its impact on the patients during the first 12 months of the INHD service. Patients were interviewed at initiation of INHD and then at six and 12 months. Thematic analysis was used to provide a descriptive account of receiving HD therapy in an in-centre environment at night. Findings of the study showed that INHD has positive effects on physical health and lifestyle, but that patients also experienced new symptoms related to longer hours of dialysis and poor sleep quality. Patients felt isolated from the rest of the dialysis patients and adapted the INHD environment to suit their own personal needs. INHD is a new approach to the delivery of HD treatments, which has been developed in response to the increasing demand for dialysis services. More study is required into this novel model of care to understand the risks and benefits of INHD to patients and staff, and to optimise the delivery of safe and effective HD. [ABSTRACT FROM AUTHOR]

Zostera muelleri is an abundant seagrass species distributed through intertidal and shallow subtidal waters on the subtropical coasts of Australia. The vertical distribution of Zostera is likely defined by tidal influences, particularly desiccation and light reduction stresses. These stresses were expected to affect the flowering of Z. muelleri; however, it is difficult to quantify the effects of tidal inundation with field studies due to multiple confounding environmental factors affecting flowering (e.g., water temperature, herbivory, nutrients). A laboratory aquarium experiment compared the effects of two levels of tidal height (intertidal and subtidal) and light intensity (shaded and unshaded) on flowering timing, abundance, the ratio between flowering shoots and vegetative shoots, the morphology and duration of flower development. The earliest and greatest flowering intensity was recorded in the subtidal-unshaded group, with no flowers observed in the intertidal-shaded group. Notably, the peak flowering time was the same across shaded and unshaded treatments. Shading prolonged the timing of the first flowering and reduced the density of flowering shoots and spathes, while tidal inundation had a more significant effect on the density of flowering shoots and the density of spathes. Results showed that Z. muelleri could flower under low light conditions or tidal stress but not when exposed to both stresses simultaneously in a laboratory 'nursery setting'. Therefore, applying subtidal-unshaded conditions appears to be beneficial for seagrass nurseries aimed at improved flower abundance despite the plants previously being collected from and adapted to intertidal meadows. Further studies that explore the suitable conditions for triggering and optimising the flowering will be beneficial in designing cost-effective seagrass nurseries., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Global population growth and associated urban development are having profound effects on biodiversity. Two major outcomes of expanding development that affect wildlife are light and noise pollution. In this paper, we review literature reporting the effects of light and noise on biodiversity, and assess implications for conservation planning in Australia. Our results clearly indicate that light and noise pollution have the potential to affect the physiology, behaviour and reproduction of a range of animal taxa. Types of effects include changes in foraging and reproductive behaviours, reduction in animal fitness, increased risk of predation and reduced reproductive success. These could have flow-on consequences at the population and ecosystem levels. We found a significant gap in knowledge of the impact of these pollutants on Australian fauna. To reduce the effect of light and noise pollution, there needs to be careful planning of urban areas in relation to protected areas, and for biodiversity more generally. Potential measures include strategically planning the types of development and associated human activities adjacent to protected areas, and the use of shields and barriers, such as covers for lights or the use of dense native vegetation screens, while still allowing movement of animals. Changes in government standards and regulations could also help to reduce the impacts of light and noise pollution. [ABSTRACT FROM AUTHOR]

Purpose The aim of this literature review is to critically evaluate the current literature regarding the use of two types of diagnostic imaging devices (narrow band imaging and white light' used during a colonoscopy procedure). This exploration of the literature will aim to determine which imaging device is considered the superior choice for detecting the diagnosis of cancer during these procedures. Method A literature review was undertaken using the following keywords; 'white light', 'narrow band imaging', 'detection of cancer' and 'colonoscopy'. The search was limited by seeking results with the criteria of full text articles, published within the past five years from scholarly journals and written in English. Results The results for this literature review varied greatly, from large randomised controlled trials stating that narrow band imaging did not lead to an increase in the adenoma detection rate whilst other randomised controlled trials using tandem colonoscopy did find an improvement in the overall detection rate. One study also concluded that narrow band imaging had a more superior accuracy to predict adenomas in real time compared with standard definition white light and high definition white light. Conclusion Whilst the majority of literature stated that narrow band imaging had no statistically significant evidence in improving adenoma detection in colonoscopies, a small quantity of articles presented that narrow band imaging could possibly have a role to play in detection of adenomas during a colonoscopy but authors recommend that further studies be conducted in the future using a larger sample size for a more accurate result. [ABSTRACT FROM AUTHOR]

Photographs of and by indigenous people in colonial countries have received considerable scholarly attention since the 1980s, but the role of colonisation in shaping the meaning of photography has been widely neglected. This article addresses this lacuna by focusing on metaphors of light, darkness and race, through which photography was made meaningful in colonial Australia. Representations of Aboriginality in photographs and in cartoons addressing photography are analysed to reveal how colonialist assumptions about race, light and darkness inform conceptions of Australian photography as process, brand and movement. [ABSTRACT FROM AUTHOR]

The traditional methods of forest classification, based on the interpretation of aerial photographs and processing of multi-spectral and/or hyper-spectral remote sensing data are limited in their ability to capture the structural complexity of the forests compared with analysis of airborne LiDAR (light detection and ranging) data. This is because of LiDAR's penetration of forest canopies such that detailed and three-dimensional forest structure descriptions can be derived. This study applied airborne LiDAR data for the classification of cool temperate rainforest and adjacent forests in the Strzelecki Ranges, Victoria, Australia. Using normalised LiDAR point data, the forest vertical structure was stratified into three layers. Variables characterising the height distribution and density of forest components were derived from LiDAR data within each of these layers. The statistical analyses, which included one-way analysis of variance with post hoc tests, identified effective variables for forest-type classifications. The results showed that using linear discriminant analysis, an overall classification accuracy of 91.4% (as verified by the cross-validation) was achieved in the study area. [ABSTRACT FROM AUTHOR]

Abstract: Steady state and dynamic responses of two tree fern species of contrasting origins, Dicksonia antarctica (of Gondwanan origin) and Cyathea australis (Pan-tropical), were studied over two consecutive years under field conditions in a wet sclerophyll forest of south-east Australia. Irrespective of their different origins, there were no significant differences in photosynthetic performance between the two species. Growth irradiance and leaf temperature, but not plant water status, was significantly related to photosynthetic and morphological traits. At a common leaf temperature, maximum light-use efficiency of photosystem II (F v/F m) was significantly lower in winter than in summer, suggesting some limitation to PSII efficiency potentially associated with cold winter mornings. Both species displayed seasonal acclimation in a number of measured photosynthetic parameters and frond traits (i.e. F v/F m, A sat, g s, N A, total chlorophyll, SLA). Acclimation of stomatal density to spatial variation in growth irradiance seemed limited in both species, although stomatal pattern differed between species. Because there were no significant differences between the two species in photosynthetic parameters, both species can be described by common carbon gain and water use models at the leaf scale. [ABSTRACT FROM AUTHOR]

• Here, we evaluated how increased shading and declining net photosynthetic capacity regulate the decline in net carbon balance with increasing leaf age for 10 Australian woodland species. We also asked whether leaves at the age of their mean life-span have carbon balances that are positive, zero or negative. • The net carbon balances of 2307 leaves on 53 branches of the 10 species were estimated. We assessed three-dimensional architecture, canopy openness, photosynthetic light response functions and dark respiration rate across leaf age sequences on all branches. We used YPLANT to estimate light interception and to model carbon balance along the leaf age sequences. • As leaf age increased to the mean life-span, increasing shading and declining photosynthetic capacity each separately reduced daytime carbon gain by approximately 39% on average across species. Together, they reduced daytime carbon gain by 64% on average across species. • At the age of their mean life-span, almost all leaves had positive daytime carbon balances. These per leaf carbon surpluses were of a similar magnitude to the estimated whole-plant respiratory costs per leaf. Thus, the results suggest that a whole-plant economic framework, including respiratory costs, may be useful in assessing controls on leaf longevity. [ABSTRACT FROM AUTHOR]

• Biocrust hydration led to a large and immediate increase in soil CO 2 flux. • Hydration initiates photosynthesis in some, but not all biocrusts. • Biocrusts are highly spatially variable at both landscape and small scales. Soil biocrusts, formed from communities of microbes and their extracellular products are a common feature of dryland soil surfaces. Biocrust organisms are only intermittently metabolically active, but due to their ubiquity they make a significant contribution to the carbon cycle. Quantification of the controls and insights into the interlinked process of photosynthesis and respiration are essential to enhancing our understanding of the carbon cycle in the world's drylands. Yet, there have been relatively few field studies investigating controls on both biocrust photosynthesis and respiration. We undertook field-based experiments at two dune sites during the dry season in Diamantina National Park in Queensland, Australia to determine how biocrust hydration and illumination affect soil CO 2 flux and photosynthesis. Static chambers and an infra-red gas analyser were used to quantify soil CO 2 flux, and a fluorometer and a CFImager were used to determine a range of photosynthetic parameters in the field and laboratory respectively. When dry, biocrust photosynthetic activity was not detected and soil CO 2 flux was very low irrespective of biocrust cover. Hydration led to a large and immediate increase in CO 2 flux, which was more pronounced in the presence of biocrusts and on the dune with thinner biocrusts. Hydration also initiated the onset of photosynthesis in some biocrusts, which was greatest under low light conditions and sustained with further hydration. There were only infrequent periods of net CO 2 uptake to the soil, occurring when CO 2 uptake due to photosynthetic activity was less than background soil CO 2 flux. Chlorophyll fluorescence imaging indicated biocrust spatial heterogeneity was evident at the cm scale where microtopography creates a myriad of environments for different crust organisms. Our findings demonstrate that biocrusts are highly spatially heterogenetic at both landscape and small scale, which suggests the maintenance of biocrust spatial diversity is likely to be key to imparting resilience to changing climate and disturbance. As well as reaffirming the importance of biocrusts for the carbon cycle in dryland dune soils the study demonstrates that biocrust respiration and photosynthesis respond differently to hydration and shading. This adds an unpredictability to the distribution of soil carbon stocks and the gaseous exchanges of CO 2 between the surface and atmosphere. Future changes to precipitation and increased temperatures are likely to reduce soil moisture across much of the Australian interior and consequently biocrusts may experience a decline in biomass, structure, and function which could have significant repercussions beyond carbon stocks. [ABSTRACT FROM AUTHOR]

To assess the likely effects on three coexisting species of Australian freshwater fish of riparian loss, we examined the temperature, light, and habitat preferences of each species in relation to commonly documented effects of riparian degradation on stream environments. Such effects include reduced shade, instream structure, and water depth and increased temperature and invasive instream vegetation. Xiphophorus helleri, Gambusia holbrooki, and Melanotaenia duboulayi differed significantly in mean swimming depth, preferences for light and habitat, and in their patterns of behavioural change through the day. Values of interspecific spatial overlap (25–58%) indicated that the overall environmental preferences of G. holbrooki, X. helleri, and M. duboulayi were reasonably distinct. Habitat alterations associated with riparian removal are likely to favour the exotic species G. holbrooki over the native species M. duboulayi, but the results for X. helleri suggest that not all poeciliid␣species are strong indicators of degraded conditions. [ABSTRACT FROM AUTHOR]

The role of dormancy, temperature and light in the regulation of seed germination of four annual Asteraceae from south‐western Australia was investigated. The experiments aimed to identify after‐ripening patterns, and to relate these to climatic conditions of the habitat in which the species occur. Seeds of all species were strongly dormant at maturity and maintained high levels of dormancy for time periods corresponding to the duration of summer in south‐western Australia. Dry after‐ripening was promoted best by temperatures lower than those prevailing in the dry season, although differences among storage temperatures were mostly insignificant. Germination percentages were highest at average winter temperatures (15 °C). A logistic model revealed significant differences in germinability among species, but not between incubation temperatures or light and dark treatments across species. Three species with seeds >0·5 mg germinated better in darkness than in light, whereas germination in darkness was almost inhibited in the species with the smallest seeds (0·14 mg). The course of dormancy loss, tested over a range of fluctuating incubation temperatures (7–30 °C), showed that seeds of three species came out of dormancy first at temperatures that prevail in south‐western Australia during the winter (10–15 °C). Seeds from one species, introduced from South Africa, first lost dormancy at the lowest temperature (7 °C). All species showed after‐ripening patterns of Type 1, typical of species growing in Mediterranean climates. The germination characteristics of the investigated species can be interpreted as ensuring that initial growth and establishment occur during the winter growing season, thereby avoiding the hot and dry summer conditions that follow seed dispersal. [ABSTRACT FROM PUBLISHER]

1. We used artificial substrata in forested and open streams in South-East Queensland, Australia, to determine the relative importance of shading from riparian vegetation and of nutrients on periphyton growth, and whether nitrogen and/or phosphorus limited algal productivity. 2. Nutrient-diffusing substrata consisting of agar enriched with N, P and N + P, and controls without nutrients, were deployed in duplicate at 15 sites in headwater streams with riparian canopy cover ranging from 0 to 88%. 3. Shading was the over-riding factor controlling periphyton biomass accrual on the artificial substrata, with nutrients playing a relatively minor role. Microscopic examination of periphyton scrapings taken after 7 weeks revealed that diatoms dominated on the artificial substrata in shaded streams, whereas filamentous green algae dominated the algal assemblage in the more open canopy streams. 4. Whilst nutrients had little effect on the accrual of algal biomass compared with riparian shading, there was evidence that nitrogen, and not phosphorus, stimulated periphyton production in streams with sufficient light. [ABSTRACT FROM AUTHOR]

Environmentally cued germination may play an important role in promoting coexistence in Mediterranean annual plant systems if it causes niche differentiation across heterogeneous microsite conditions. In this study, we tested how microsite conditions experienced by seeds in the field and light conditions in the laboratory influenced germination in 12 common annual plant species occurring in the understorey of the York gum-jam woodlands in southwest Western Australia. Specifically, we hypothesized that if germination promotes spatial niche differentiation, then we should observe species-specific germination responses to light. In addition, we hypothesized that species' laboratory germination response may depend on the microsite conditions experienced by seeds while buried. We tested the laboratory germination response of seeds under diurnally fluctuating light and complete darkness, which were collected from microsites spanning local-scale environmental gradients known to influence community structure in this system. We found that seeds of 6 out of the 12 focal species exhibited significant positive germination responses to light, but that the magnitude of these responses varied greatly with the relative light requirement for germination ranging from 0.51 to 0.86 for these species. In addition, germination increased significantly across a gradient of canopy cover for two species, but we found little evidence to suggest that species' relative light requirement for germination varied depending on seed bank microsite conditions. Our results suggest that variability in light availability may promote coexistence in this system and that the microsite conditions seeds experience in the intra-growing season period can further nuance species germination behaviour., (© 2021. The Author(s).)

At Chaffey Dam, New South Wales, Australia, Anabaena circinalis filaments accumulated at the surface as diurnal surface layer thermal stratification developed. Previously buoyant, homogeneously distributed colonies accumulated in the top 2 m, but a proportion lost buoyancy. Similarly, a percentage of A.circinalis suspended in bottles lost buoyancy at depths experiencing >30% surface irradiance (Io). Nutrient addition reduced the proportion of filaments that lost buoyancy following a full day of high irradiance. The greatest axial linear dimension (GALD) was measured for A.circinalis deployed in bottles at three depths in the reservoir. GALD increased in samples exposed to 1 and 30% Io by the following day. The rank order of GALD from smallest to largest grouped samples exposed to 70, 30 and 1% Io, suggesting that increasing GALD is a function of irradiance. The increased GALD of biomass units was attributed to aggregation of filaments in low light. The enlargement of biomass units increased the mean floating velocity, supporting the theory that filament aggregation may be a strategy, utilized by light-limited filaments, to increase light exposure. High irradiance increased the carbohydrate content of cells and decreased the floating velocity of filaments. [ABSTRACT FROM PUBLISHER]

Akineles of a clonal culture of Anabaena circinalis, Rabenhorst from Mt. Bold reservoir (eutrophic), South Australia, were isolated and the effects of hight, phosphorus, and nitrogen availability on their germination were investigated. Light was required but there was no significant difference in percentage of germination after 72 h if akinetes were incubated in ASM-1 medium at irradiances of 15, 30, or 50 μ mol-m[sup-2]s[sup-1]. Maximum akinete germination occurred by 48 h. Nitrogen was not required, as 88% of akinetes germinated in the flasks without combined nitrogen added to the medium and without N[sub2] in the air, NH[sub4,sup3]-N at 28 mg N-L[sup-1] completely suppressed germination, whereas 28 mg NO[sub3] N-L[SUP-1] had no effect relative to the controls without nitrogen. Phosphorus was required, and at 48 h percentage of germination in the flasks with 0.6 mg P-L[SUP-1] added (78%) was significantly greater than in the flasks with 0.06 P-L[[sup-1] (58%) and 0 mg P-L[SUP-1] (24%) added. Germlings in the 0 mg P-L[SUP-1] flasks were only 2-4 cells long and stunted in appearance, whereas germlings at all other P concentrations were 8-16 cells long. It is likely that the isolation process exposed some akinetes to intracellular phosphorus released from lysing vegetative cells, but this was insufficient to allow normal development in the 0 mg P-L[SUP-1] flasks. The plot of percentage of germination vs. intitial phosphorus concentration in the medium showed a relationship analogous to Michaelis-Menten nutrient uptake kinetics, suggesting that a specific membrance-bound enzyme system(s) is involved, with phosphorus as the substrate. The half saturation value (K[subs]) for germination was 50 μg P-L[sup-1]. [ABSTRACT FROM AUTHOR]

The article provides information about a study, which measured the relative differences in the seasonality of light penetrating the canopies of three Australian rainforest. They were measured directly with a quantum meter and indirectly using hemispherical photographs. Because these rainforests exhibit degrees of seasonality in leaf-fall and leaf replacement, it is postulated that the amount of sky visible from the forest floor up through the canopy will exhibit temporal fluctuations relative to the proportion of leaf loss. Profile diagrams were constructed at each site to illustrate the depth and stratification of the canopy, and the differences in these structural features were related to the variation in light attenuation.