Imaging the environmental ultraviolet

A technique has been developed to visually represent measured environmental ultraviolet radiation using a digital photograph and measurements of the UV and visible light intensity. The method involves the use of a personal pocket UV meter, an optional lux meter and a simple image processing technique to present visual images that are weighted to the ambient ultraviolet, providing images that highlight regions of high ultraviolet intensity that can be compared with a visible photograph. The technique described, provides a method students can follow to better develop an understanding of the potentially harmful ultraviolet irradiance with respect to visible daylight, indicating that the ambient ultraviolet and visible environment are not directly related, with ultraviolet intensity being dependent on many different factors and not the visual brightness of the location alone

Alternative methods for the reduction of evaporation: practical exercises for the science classroom

Across the world, freshwater is valued as the most critically important natural resource, as it is required to sustain the cycle of life. Evaporation is one of the primary environmental processes that can reduce the amount of quality water available for use in industrial, agricultural and household applications. The effect of evaporation becomes intensified especially during conditions of drought, particularly in traditionally arid and semi-arid regions, such as those seen in a number of countries over the past 10 years. In order to safeguard against the influence of droughts and to save water from being lost to the evaporative process, numerous water saving mechanisms have been developed and tested over the past century. Two of the most successful and widely used mechanisms have included floating hard covers and chemical film monolayers. This paper describes a laboratory based project developed for senior high school and first year university classes, which has been designed to introduce students to the concepts of evaporation, evaporation modelling and water loss mitigation. Specifically, these ideas are delivered by simulating the large-scale deployment of both monolayers and floating hard covers on a small water tank under numerous user defined atmospheric and hydrodynamic conditions, including varying surface wind speeds and underwater bubble plumes set to changing flow rates

A site-specific standard for comparing dynamic solar ultraviolet protection characteristics of established tree canopies

A standardised procedure for making fair and comparable assessments of the ultraviolet protection of an established tree canopy that takes into account canopy movement and the changing position of the sun is presented for use by government, planning, and environmental health authorities. The technique utilises video image capture and replaces the need for measurement by ultraviolet radiometers for surveying shade quality characteristics of trees growing in public parks, playgrounds and urban settings. The technique improves upon tree shade assessments that may be based upon single measurements of the ultraviolet irradiance observed from a fixed point of view. The presented technique demonstrates how intelligent shade audits can be conducted without the need for specialist equipment, enabling the calculation of the Shade Protection Index (SPI) and Ultraviolet Protection Factor (UPF) for any discreet time interval and over a full calendar year

Annual measurement of solar UVB at a reef site using a polyphenylene oxide dosimeter

Numerous investigations detailed over the last thirty years have highlighted how solar UV (290-400 nm) can have a detrimental effect on coral health. It has also been postulated that coral bleaching is caused by a synergistic process between high water temperatures and increases in UV. As a consequence of its influence upon coral ecosystems, UV radiation must be monitored in underwater locations using an appropriate non-invasive measurement technique in order to better understand the damage it causes on both a macro and micro scale and provide solutions on how to adequately manage its impact. The high energy UVB waveband (290-320 nm) is believed to have the greatest negative influence on coral stress. This report details the employment of a simple, easily deployable UVB measuring dosimeter system based on polyphenylene oxide (PPO) at a coral reef location near Hervey Bay (25°17 S, 152°52′ E) over the interval of one year. Continual deployment of the PPO dosimeters measured a clear inverse correlation between tide level and UVB penetration, with the highest coral UVB exposures measured during the months of winter and spring (coinciding with typically lower tidal conditions during this time). This suggests that the UVB incident on Queensland coral reefs may not be strictly dependent on solar zenith angle (the Sun’s position in the sky), which is generally the primary factor in determining the extent of terrestrial UVB exposures. Further, this may mean that photo-damage incident on corals could be exacerbated in traditionally cooler months if current global warming trends continue

Dosimeter based on 8-Methoxypsoralen for UVA exposures over extended periods

A miniaturized UVA dosimeter based on 8-methoxypsoralen (8-MOP) has been developed and characterized for the evaluation of UVA (320 - 400 nm) exposures over extended periods longer than one day. Current research indicates that UVA is a contributing factor in non-melanoma skin cancers and the associated financial cost of damage caused by UVA is significant. Dosimetry is a technique that is commonly employed to measure UV exposures to an object or subject. Miniaturized dosimeters using polyphenylene oxide (PPO) have previously been used to measure received erythemal UV (UVery) exposures. A new miniaturized dosimeter using 8-MOP as the photoactive material has been characterized and a technique developed for the calibration of UVA exposures. Using Mylar as a UVB filter the spectral response showed 8-MOP to react only to wavelengths between 320 - 400 nm. The measured cosine response has an error of less than 13.8% for angles between 0° and 60°. Seasonal dose response tests conducted, indicate that these UVA dosimeters are able to measure exposures < 4.6 kJ/m2. These results have shown that a dosimeter constructed from 8-MOP in conjunction with a Mylar filter can measure UVA exposures over extended periods longer than one day

A fine balance and a shared learning journey: Exploring healthcare engagement through the experiences of youth with neuromuscular disorders

BACKGROUND: Youth with Neuromuscular Disorders (NMD) who are wheelchair users can now survive well into adulthood if their multisystem comorbidities are prudently managed. Uptake of health behaviors may optimize their health outcomes. OBJECTIVE: To explore youths’ perceptions of health, health behaviors and healthcare engagement. METHODS: This qualitative study purposefully recruited 11 youth with NMD from a concurrent, population-based study for variability of age, gender, type of NMD and their ratings of motivation and engagement. Interview data were analyzed and synthesized by thematic content. RESULTS: Participants perceived healthcare engagement as being given tools (knowledge and responsibility) and using them to maintain their finely balanced health. Nested in adequate social, emotional and physical support, they took responsibility for creatively integrating health behaviors they felt were informed by credible knowledge, gained primarily through personal experience. CONCLUSION: Cognizant of their compromised health, youth with NMD in this study were motivated to maintain their physical health. Limited NMD condition specific knowledge challenged youths’ uptake of health behaviors. They valued a learning partnership with their healthcare professionals. By embracing the youth’s experience based knowledge and through facilitating supportive relationships, healthcare professionals co-construct youth’s healthcare engagement that may optimize health behaviors and outcomes

Characterization of cloud cover with a smartphone camera

A smartphone sky camera and associated image analysis algorithm has been developed and validated for the determination of the percentage of cloud cover. This provides the total cloud cover and the percentage of thick and thin cloud in the image. The system has been validated and tested using supervised image classification for a range of cloud types and cloud cover ranging from 4% to 98% and solar zenith angles between 6o and 49o. Additionally, this system provides the percentage of total cloud and thick and thin cloud in proximity to the solar disc. The size of the errors is comparable to those associated with the cloud fractions determined with commercial sky camera systems. The benefits of increasing the availability of cloud fraction measurements through the system described include the potential to develop improved local ultraviolet index and weather forecasts and contribute toward better understanding of local trends in cloud patterns that is required to be considered in the generation of solar energy

From ultraviolet to Prussian blue: a spectral response for the cyanotype process and a safe educational activity to explain UV exposure for all ages

Engaging students and the public in understanding UV radiation and its effects is achievable using the real time experiment that incorporates blueprint paper, an 'educational toy' that is a safe and easy demonstration of the cyanotype chemical process. The cyanotype process works through the presence of UV radiation. The blueprint paper was investigated to be used as not only engagement in discussion for public outreach about UV radiation, but also as a practical way to introduce the exploration of measurement of UV radiation exposure and as a consequence, digital image analysis. Tests of print methods and experiments, dose response, spectral response and dark response were investigated. Two methods of image analysis for dose response calculation are provided using easy to access software and two methods of pixel count analysis were used to determine spectral response characteristics. Variation in manufacture of the blueprint paper product indicates some variance between measurements. Most importantly, as a result of this investigation, a preliminary spectral response range for the radiation required to produce the cyanotype reaction is presented here, which has until now been unknown

Quantum Arrival and Dwell Times via Idealised Clocks

A number of approaches to the problem of defining arrival and dwell time probabilities in quantum theory make use of idealised models of clocks. An interesting question is the extent to which the probabilities obtained in this way are related to standard semiclassical results. In this paper we explore this question using a reasonably general clock model, solved using path integral methods. We find that in the weak coupling regime where the energy of the clock is much less than the energy of the particle it is measuring, the probability for the clock pointer can be expressed in terms of the probability current in the case of arrival times, and the dwell time operator in the case of dwell times, the expected semiclassical results. In the regime of strong system-clock coupling, we find that the arrival time probability is proportional to the kinetic energy density, consistent with an earlier model involving a complex potential. We argue that, properly normalized, this may be the generically expected result in this regime. We show that these conclusions are largely independent of the form of the clock Hamiltonian.Comment: 19 pages, 4 figures. Published versio