Australian action to reduce health risks from radon.

In Australia, worker exposure to radon in underground uranium mines has been a focus of policy makers and regulators, and has been well controlled in the industry sector. That cannot be said for public exposure to radon. Radon exposure studies in the late 1980s and early 1990s demonstrated that the levels of radon in Australian homes were some of the lowest in the world. The International Basic Safety Standards, published by the International Atomic Energy Agency, requires the government to establish and implement an action plan for controlling public exposure due to radon indoors. When considering different policy options, it is important to develop radon prevention and mitigation programmes reflecting elements that are unique to the region or country. The Australian Radon Action Plan is being considered at a national level, and presents a long-range strategy designed to reduce radon-induced lung cancer in Australia, as well as the individual risk for people living with high concentrations of radon. In Australia, workers who are not currently designated as occupationally exposed are also considered as members of the public. In the Australian context, there are only a limited set of scenarios that might give rise to sufficiently high radon concentrations that warrant mitigation. These include highly energy efficient buildings in areas of high radon potential, underground workplaces, workplaces with elevated radon concentrations (e.g. spas using natural spring waters), and enclosed workspaces with limited ventilation. The key elements for a successful plan will rely on collaboration between government sectors and other health promotion programmes, cooperative efforts involving technical and communication experts, and partnering with building professionals and other stakeholders involved in the implementation of radon prevention and mitigation.

Australia's proactive approach to radiation protection of the environment: how integrated is it with radiation protection of humans?

Australia's regulatory framework has evolved over the past decade from the assumption that protection of humans implies protection of the environment to the situation now where radiological impacts on non-human species (wildlife) are considered in their own right. In an Australian context, there was a recognised need for specific national guidance on protection of non-human species, for which the uranium mining industry provides the major backdrop. National guidance supported by publications of the Australian Radiation Protection and Nuclear Safety Agency (Radiation Protection Series) provides clear and consistent advice to operators and regulators on protection of non-human species, including advice on specific assessment methods and models, and how these might be applied in an Australian context. These approaches and the supporting assessment tools provide a mechanism for industry to assess and demonstrate compliance with the environmental protection objectives of relevant legislation, and to meet stakeholder expectations that radiological protection of the environment is taken into consideration in accordance with international best practice. Experiences from the past 5-10 years, and examples of where the approach to radiation protection of the environment has been well integrated or presented some challenges will be discussed. Future challenges in addressing protection of the environment in existing exposure situations will also be discussed.

Atmospheric transport modelling of time resolved 133Xe emissions from the isotope production facility ANSTO, Australia.

The verification of the Comprehensive Nuclear-Test Ban Treaty (CTBT) relies amongst other things on the continuous and worldwide monitoring of radioxenon. The characterization of the existing and legitimate background, which is produced mainly by nuclear power plants and isotope production facilities, is of high interest to improve the capabilities of the monitoring network. However, the emissions from legitimate sources can usually only be estimated. For this paper historic source terms of (133)Xe emissions from the isotope production facility at ANSTO, Sydney, Australia, have been made available in a daily resolution. Based on these high resolution data, different source term sets with weekly, monthly and yearly time resolution have been compiled. These different sets are then applied together with atmospheric transport modelling (ATM) to predict the concentration time series at two radioxenon monitoring stations. The results are compared with each other in order to examine the improvement of the prediction capability depending on the used time resolution of the most dominant source term in the region.

Development of an energy discriminate CR-39(®) nuclear track etch dosimeter for Radon-220 gas measurements.

An energy discriminate CR-39(®) nuclear track etch dosimeter for use in a (220)Rn and (222)Rn gas monitor has been developed and experimentally assessed. It utilises a thin film of Mylar(®) C to attenuate the alpha particle energies to allow only the damage tracks created by the 8.785 MeV alpha particles emitted from (212)Po of the (232)Th decay chain to be registered in the CR-39(®) plaque, allowing for the direct measurement of (220)Rn gas concentrations. The dosimeter was developed through a combination of experimental investigations and theoretical simulations using the Monte Carlo ion transport modelling program Stopping and Range of Ions in Materials (SRIM 2008). A film thickness of 54 µm has been shown to attenuate all alpha energies less then 7.7 MeV.

Difficulties in obtaining an HPGe detector for low-level measurements.

All low-level laboratories require HPGe detectors to meet certain technical specifications, some of which are not available from manufacturers prior to purchase. Ensuring an HPGe detector is fit for purpose requires the purchase and installation of a detector in the laboratory, incurring both financial risk and considerable time and effort. We show that the optimal HPGe crystal for low-level laboratories has a diameter matched to the source and a length providing 70% absorption of the gamma-rays of interest.

In vitro dissolution studies of uranium bearing material in simulated lung fluid.

Inhaled uranium (U) bearing material will partially dissolve in the fluid lining of the lung, followed by a combination of retention, re-distribution, and excretion of the U. The rate of dissolution influences the retention time at the site of deposition, and the extent to which the material is available for re-distribution to other tissues. The consequential radiation dose is dependent upon the material distribution in the body and the exposure time to various tissues. The International Commission on Radiological Protection, ICRP 66 [International Commission on Radiological Protection (ICRP), 1994. Human Respiratory Tract Model for Radiological Protection. ICRP Publication 66] recommends the use of experimentally determined solubility coefficients in dose modelling. Material specific absorption parameters allow for better dose estimation than using ICRP default values for F (fast), M (moderate) and S (slow) classifications of U compounds. In vitro dissolution tests were carried out on U material collected from two U mines located in Australia. A static technique was designed in which particle samples were sandwiched between two 0.1-mum pore size membrane filters. The filter sandwich was exposed to a solvent (simulated lung fluid) for selected time intervals, at controlled test conditions for temperature and pH. The collected solution was analysed for U concentration using ICP-MS. The resulting dissolution curves were fitted with a double or triple exponential equation to determine the dissolution coefficients.

Method design and validation for the determination of uranium levels in human urine using high-resolution alpha spectrometry.

Quantification of uranium in human urine is a valuable technique for assessing occupational and public exposure to uranium. A reliable method has been developed and validated in the ARPANSA Radiochemistry Laboratory by means of standard radiochemical separation and purification techniques and measurement using high-resolution alpha spectrometry. This method can be used to evaluate the levels of naturally occurring 234U, 235U and 238U in urine. Method design and validation is the process of defining an analytical requirement, and then confirming that the method under consideration has performance capabilities consistent with what the application requires. The method was designed to measure levels down to 2 mBq/day of total uranium, corresponding to approximately 1/100th of the annual committed effective dose of 20 mSv. Validation tests were developed to assess selectivity, accuracy, recovery and quantification of uncertainty. The radiochemical recovery of this method was measured using (232)U tracer. The typical minimum detectable concentration for total uranium for 24-h urine samples is approximately 0.6 mBq/day or 0.019 microg/day.

Marine radioactivity assessment of Mururoa and Fangataufa atolls.

The International Atomic Energy Agency (IAEA) carried out an international project. 'The Study of the Radiological Situation at the Atolls of Mururoa and Fangataufa' with the aim of assessing the present and future radiological situation at the atolls and making recommendations for either monitoring or remedial actions if they are deemed necessary. The paper concentrates on marine radioactivity aspects and gives an estimation of present radionuclide concentrations in water, sediment and biota of the Mururoa and Fangataufa lagoons and the surrounding ocean. The dominant radionuclide in both lagoons is Pu in sediments (the total inventory is approximately 30 TBq). A decline in radionuclide concentrations has been observed in recent years in lagoon water, with the exception of 3H and 90Sr, for which a contribution from underground sources is to be expected. Radionuclide concentrations in biota from the lagoons and the surrounding ocean are low and consistent with previous measurements. The observed radionuclide concentrations in both lagoons imply that no radiological risk exists for hypothetical inhabitants of Mururoa and Fangataufa Atolls.

Requirement for the vasa RNA helicase in gurken mRNA localization.

Localization of specific mRNAs to distinct sites within the Drosophila oocyte is an early and key step in establishing the anterior-posterior and dorsal-ventral axes. We describe a new function for the RNA helicase encoded by the "posterior" group gene vasa (vas) in control of localization of the mRNA encoded by the "dorsal-ventral" patterning gene gurken (grk). Two new ethyl methane sulfonate-induced, female sterile alleles of vas have been isolated. In these mutants grk mRNA fails to become localized properly and GRK protein is barely detectable. Surprisingly fs(1)K10, a recessive female sterile mutation that results in mislocalization of GRK mRNA to the anterior end of the oocyte, is epistatic to these vas alleles. This result demonstrates that GRK protein levels sufficient to dorsalize the egg chamber can accumulate in vas mutants, if fs(1)K10 is also mutant. Taken together these results suggest that regulation of GRK mRNA localization normally occurs, directly or indirectly, through the VAS RNA-dependent RNA helicase and may suggest that accumulation of GRK protein normally depends on GRK mRNA localization.

Nursing students' approaches to studying.

The Approaches to Study Inventory (ASI), developed by Entwistle & Ramsden (1983), was administered to all nursing students at an Australian university (response rate = 67%). The purpose was to find out whether ASI constructs also apply to nursing students and to see whether nursing students change in their study approaches in the course of their nursing education. The ASI was construct validated through factor analysis. While it was possible to reconstruct a majority of the subscales based on individual items, only the meaning and reproducing study orientations were supported. These two orientations also demonstrated satisfactory levels of internal consistency for group comparisons. The authors conclude that the ASI is a useful and robust instrument for use in nursing education with respect to the two main study orientations. Ideally, nursing education should successively pave the way for an increase in meaning orientation scores (deep learning) and a reduction in reproducing orientation scores (surface learning). However, in this study there was no change in study orientations from first to third year. The association between meaning orientation scores and academic performance was weak.

Fifteen-month follow-up of eye movement desensitization and reprocessing (EMDR) treatment for posttraumatic stress disorder and psychological trauma.

The present study is a 15-month follow-up of the effects of eye movement desensitization and reprocessing (EMDR) therapy on the functioning of 66 participants, 32 of whom were diagnosed with posttraumatic stress disorder (PTSD) prior to treatment, PTSD participants improved as much as those without the diagnosis, with both groups maintaining their gains at 15 months. At 15-month follow-up, the three 90-min sessions of EMDR previously administered (S.A. Wilson, L.A. Becker, & R. H. Tinker, 1995) produced an 84% reduction in PTSD diagnosis and a 68% reduction in PTSD symptoms. The average treatment effect size was 1.59; the average reliable change index was 3.37. Implications of the maintenance of EMDR treatment effects are discussed.

Eye movement desensitization and reprocessing (EMDR) treatment for psychologically traumatized individuals.

The effects of 3 90-min eye movement desensitization and reprocessing (EMDR) treatment sessions on traumatic memories of 80 participants were studied. Participants were randomly assigned to treatment or delayed-treatment conditions and to 1 of 5 licensed therapists trained in EMDR. Participants receiving EMDR showed decreases in presenting complaints and in anxiety and increases in positive cognition. Participants in the delayed-treatment condition showed no improvement on any of these measures across the 30 days before treatment, but after treatment participants in the delayed-treatment condition showed similar effects on all measures. The effects were maintained at 90-day follow-up.

The COOH-terminal domain of the RNA polymerase alpha subunit in transcriptional enhancement and deactivation at the bacteriophage T4 late promoter.

Many activator proteins generate their positive control of transcription through interactions with the COOH-terminal domain of the Escherichia coli RNA polymerase alpha subunit. We have examined the participation of this alpha-domain in transcriptional enhancement and suppression at bacteriophage T4 late promoters. Enhancement is generated by the T4 gene 45 protein, which is the DNA-tracking processivity factor of viral DNA replication; suppression of unenhanced transcription is generated by the RNA polymerase-binding co-activator T4 gene 33 protein. Enhanced and unenhanced transcription by RNA polymerase reconstituted with intact and truncated alpha subunits and by RNA polymerase containing ADP-ribosylated alpha has been compared; the internal structures of transcription complexes formed with these RNA polymerases have also been analyzed by footprinting and photocross-linking. Comparison of these structural and functional analyses suggests that enhancement of T4 late transcription by gp45 is not compatible with any significant role of the COOH-terminal domain of the RNA polymerase core alpha subunit in transcriptional initiation. Suppression of unenhanced T4 late transcription by the gene 33 protein also does not require the COOH-terminal domain of alpha.

Old phage, new insights: two recently recognized mechanisms of transcriptional regulation in bacteriophage T4 development.

The regulation of bacteriophage T4 middle and late gene expression involves previously unrecognized mechanisms. Middle transcription requires a DNA-binding transcriptional activator and a sigma 70-binding co-activator. The coupling of late transcription to DNA replication is effected by a DNA-tracking protein that is loaded onto DNA by an assembly factor at enhancer-like entry sites. Late transcription also requires an RNA polymerase core-binding co-activator. The co-activators of T4 middle and late transcription share the property of depressing unactivated, basal transcription.

Detecting the ability of viral, bacterial and eukaryotic replication proteins to track along DNA.

The phage T4 gene 45 protein (gp45), Escherichia coli beta and the eukaryotic proliferating cell nuclear antigen (PCNA) function in replication as processivity factors of their corresponding DNA polymerases. The T4 gp45 also functions as the transcriptional activator that connects expression of viral late genes to DNA replication. DNA tracking is an essential component of the replication and transcription regulatory functions of T4 gp45. The ability of gp45, beta and PCNA to track along DNA has been analyzed by photocrosslinking. Each of these proteins must be loaded onto DNA by a species-specific assembly factor. For gp45 and beta, the density of traffic along DNA is determined by a dynamic balance between continuous protein loading and unloading, and is also dependent on interaction with the conjugate single-stranded DNA binding protein.

Transcriptional activation by a DNA-tracking protein: structural consequences of enhancement at the T4 late promoter.

Transcriptional initiation at bacteriophage T4 late promoters is activated from enhancer-like distal sites by the T4 gene 44, 62, and 45 DNA polymerase accessory proteins (gp44, gp62, and gp45, respectively). Enhancement is ATP hydrolysis-dependent and requires protein tracking along DNA. The structural analysis of the enhanced transcription initiation complex shows gp45 located at the upstream end of this promoter complex in the vicinity of its transcriptional coactivator, the T4 gene 33 protein. The ATP-cleaving gene 44 protein-gene 62 protein complex serves as the assembly factor for gp45, but does not stably associate with the enhanced promoter complex. Transcriptional enhancement quantitatively favors, but does not qualitatively change, DNA strand separation in the transcription bubble. A model of the transcriptional activation that rationalizes its DNA-tracking and activation-polarity properties is presented.

The DNA replication fork can pass RNA polymerase without displacing the nascent transcript.

Replication proteins encoded by bacteriophage T4 generate DNA replication forks that can pass a molecule of Escherichia coli RNA polymerase moving in the same direction as the fork in vitro. The RNA polymerase ternary transcription complex remains bound to the DNA and retains a transcription bubble after the fork passes. The by-passed ternary complex can resume faithful RNA synthesis, suggesting that the multisubunit RNA polymerase of E. coli has evolved to retain its transcript after DNA replication, allowing partially completed transcripts to be elongated into full-length RNA molecules.