Develop real-time dosimetry concepts and instrumentation for long term missions

The development of a rugged portable instrument to evaluate dose and dose equivalent is described. A tissue-equivalent proportional counter simulating a 2 micrometer spherical tissue volume was operated satisfactorily for over a year. The basic elements of the electronic system were designed and tested. And finally, the most suitable mathematical technique for evaluating dose equivalent with a portable instrument was selected. Design and fabrication of a portable prototype, based on the previously tested circuits, is underway

Dynamics, interactions and ecosystem implications of mesoscale eddies formed in the southern region of Madagascar

Includes bibliographical references.Several species of marine organisms occurring off the southern African coast have been found to be identical to those occurring in the Madagascan coastal water although the reason for this is unknown. It has been proposed that eddies act as a vector of transport for planktonic larvae from the Madagascar island to the southern African east coast. In this study it is shown that eddies spawned off southern Madagascar entrain chlorophyll-a rich coastal waters into their periphery. This is indicative of the mechanism whereby organisms could become entrained in eddies. Approximately one eddy per year, usually cyclonic, interacts with the southern Madagascan coast, then from its origin crosses the southern Mozambique Channel and arrives at the African coast where it dissipates. By tracking eddies and combining their trajectories with drifter data and satellite remote sensing observations of ocean colour, it is shown that chlorophyll-a rich waters are entrained within the eddies, and these waters are mostly conserved during their passage across the channel. This study suggests that biota may be transported from Madagascar to Africa in eddies, providing further evidence that eddies are potentially a viable mechanism for the transport of organisms across the southern Mozambique Channel

A study of Mesoscale Eddies, the Agulhas current and the evolution of its meanders using satellite observations and numerical modelling experiments

The Agulhas Current is the strongest western boundary current in the Southern Hemisphere and plays an important role in the exchange of heat and salt between the Indian and South Atlantic Ocean basins, thereby affecting global climate. The variability in the northern Agulhas Current is influenced by both cyclonic and anticyclonic mesoscale eddies, originating from the Mozambique Channel and south of Madagascar (known as source region eddies) and which propagate toward the offshore edge of the Agulhas Current. Using a combination of an eddy-tracking data set with in-situ surface drifter observations and altimetry-derived geostrophic currents, it is shown that source region eddies dissipate upon approaching the Agulhas Current. Their entrainment into the Agulhas Current affects its mean velocity and offshore position through a transfer of momentum, with anti-cyclonic eddies consistently increasing the Agulhas Current’s velocity by 0.16 ± 0.17 m.s -1 . In contrast, entrainment of cyclonic eddies results in a decrease in velocity by 0.13 ± 0.16 m.s-1 and shifting the current up to 144 ± 85 km offshore. These velocity anomalies propagate downstream at rates of 44 km.d-1 (anti-cyclonic eddies) and 23 km.d-1 (cyclonic eddies). Whilst existing numerical models are successfully able to capture many aspects of the Agulhas Current, many models are unable to accurately represent the observed eddy dissipation and interaction processes, affecting our understanding of mesoscale variability within in the current. In this study, we compare two simulation experiments in a regional Hybrid Coordinate Ocean Model (HYCOM), where we change the wind forcing, and using an eddy tracking algorithm assess the local effect of the changed wind stress on source region eddies and their interaction with the northern Agulhas Current. There is an overall reduction in eddy kinetic energy (EKE) of 33% over the Agulhas Current domain. Changes in eddy pathways, properties and energy conversion terms, resulting from the change in forcing from absolute to relative winds (the wind speed relative to the current speed) have resulted in significantly different mesoscale eddies in the regional HYCOM. The effects of the change in wind forcing on the variability within the Agulhas Current were examined and the differences between the two simulations were found to be very small. Finally, the evolution of meanders in the Agulhas Current, including the properties and dissipation of smaller meanders as well as mesoscale Natal Pulses type meanders, were assessed using both HYCOM experiments and compared to satellite observations. The representation of smaller meanders (under 50km in size) improved with the changed in wind forcing. However, larger Agulhas Current meanders (greater than or equal to 50km) which previously occurred too frequently in the regional HYCOM, are now too infrequent in the regional HYCOM, with an average of 1.1 meanders occurring each year. A decrease in the frequency of larger meanders was observed from the location offshore of Port Edward (30.22° E, 31.05° S) to the region of the ACT array (27.48° E, 33.35° S), in the satellite data as well as both model experiments, indicating that some of the meanders have dissipated and that both regional HYCOM models are able to resolve this

New larval food plant associations for some butterflies and diurnal moths (Lepidoptera) from the Northern Territory and Kimberley, Australia. Part II

This paper documents 103 Lepidoptera-plant associations for eight families of butterflies/diurnal moths (Castniidae, Immidae, Hesperiidae, Papilionidae, Pieridae, Nymphalidae, Lycaenidae and Noctuidae (Agaristinae)) from the ‘Top End’, central Australia and Kimberley, of which 86 associations are newly recorded for Australia and 17 are newly recorded for the Northern Territory and/or Western Australia. Of particular note are the first recordings of the families Lauraceae for Graphium eurypylus (Papilionidae), Phyllanthaceae for Hypolycaena phorbas (Lycaenidae), and Anacardiaceae for Prosotasdubiosa (Lycaenidae). Sixteen native plant genera are newly recorded for the following genera of Lepidoptera in Australia: Semecarpus (Anacardiaceae) for Prosotas (Lycaenidae), Sarcolobus (Apocynaceae) for Danaus (Nymphalidae), Vitex (Lamiaceae) for Charaxes (Nymphalidae), Bossiaea and Tephrosia (Fabaceae) for Jamides (Lycaenidae), Amyema (Loranthaceae) for Birthana (Immidae), Corymbia (Myrtaceae) for Anthene (Lycaenidae), Aristida and Digitaria (Poaceae) for Hypocysta (Nymphalidae), Chrysopogon and Eriachne (Poaceae) for Pelopidas (Hesperiidae), Mnesithea (Poaceae) for Pelopidas and Telicota (Hesperiidae), Sacciolepis (Poaceae) for Taractrocera (Hesperiidae), Sorghum (Poaceae) for Synemon (Castniidae) and Neohesperilla (Hesperiidae), Whiteochloa for Borbo and Taractrocera (Hesperiidae), and Breynia (Phyllanthaceae) for Hypolycaena (Lycaenidae). The significance of the new plant associations is discussed for the following species: Birthana cleis, Graphium eurypylus, Danaus affinis, Mycalesis sirius, Ogyris amaryllis, Candalides margarita, Famegana alsulus, Euchrysops cnejus and Freyeria putli

The biology and conservation of the Damara Tern in Namibia

The globally Near-threatened Damara Tern Sterna balaenarum is little known and faces several conservation issues. The aim of this study was to provide a description of the ecology and numbers of the species and discuss conservation management plans that will effectively ensure its survival

Observations on site fidelity in the imperial hairstreak, Jalmenus evagoras (Donovan, 1805) (Lepidoptera: lycaenidae), at Toorourong Reservoir, Victoria

Long-term observations spanning more than 20 years are reported on a breeding colony of Jalmenus evagoras (Donovan) at Toorourong Reservoir, Whittlesea, Victoria. The colony, which is still extant, persisted at this site for at least 21 years (from December 1989 to February 2011) and utilised a 7 m tall tree of Acacia melanoxylon for a minimum of 12 years and a likely maximum of 15-24 years

Microbeam Studies of the Sensitivity of Structures within Living Cells

Determining the biological effects of low doses of radiation with high linear energy transfer (LET) is complicated by the stochastic nature of charged-particle interactions. Populations of cells exposed to very low radiation doses contain a few cells which have been hit by a charged particle, while the majority of the cells receive no radiation damage. At somewhat higher doses, a few cells receive two or more events. Because the effects of damage produced by separate events can interact in the cell, we have had to make assumptions about the nature of these interactions in order to interpret the results of the experiments. Many of those assumptions can be tested if we can be sure of the number of charged-particle events which occur in individual cells, and correlate this number with the biological effect. We have developed a special irradiation facility at Pacific Northwest Laboratory (PNL) to control the actual number of charged particle tracks that pass through cell nuclei. The beam from a 2 MeV tandem accelerator is collimated to approximately 5 μm. Cells, grown in special dishes with 1.5μm thick plastic bottoms, are positioned so that the desired portion of the cell aligns with the collimator. A shutter in the beam line is opened and closed after the desired number of particle tracks has been counted. This approach can be used to investigate the effects of the interaction between irradiated and unirradiated cells in an organized system, as well as to study the effects of spatial and temporal distribution of radiation damage within single cells. We expect that this approach will lead to a better understanding of the mechanisms of high LET radiation effects

Constitutional Implications of COVID-19 : Operation of PMQs* Pre and Post-COVID-19 : House of Lords Constitution Committee : Inquiry into the Constitutional Implications of COVID-19

Our previous research has shown methodological flaws in empirical assessment of Prime Minister’s Questions (PMQs). Primarily, previous research has looked at the rate of questions (and answers) using the averages across sessions. However, though the session is intended to run for a 30-minute interval, in practice this often has exceeded this period, often running for 45 minutes or more on occasions. Applying a control for duration, we weight the frequencies of recorded behaviour during the procedure based on occurrences per 1000 words, comparing across sessions pre and post-COVID-19