Multi-agency training and the artist (Sharing our experience, Practitioner-led research 2008-2009; PLR0809/032)

The Multi-Agency Team Project approached issues of multi-agency training indirectly by using an artist as a catalyst in a group exercise examining movement and sound in relation to early childhood. The aim of the research was to run an experiential non-traditional training programme based on using an artist as a catalyst to promote inter-agency dialogue in one setting, Woodlands Park Nursery and Children’s Centre, and to analyse the findings. Eleven participants used this common experiential focus to frame collective research both as a focus group and as individual fieldworkers. The research demonstrated shared professional discourse but also collected judgements relevant to policy issues based on collaborative professional reflection triggered by the exercise. The findings are presented theoretically in terms of critical discourse analysis using the interpretation-supporting software ATLASti. We next take a further look at the role play exercise in which the group constituted itself as a ‘House of Commons Select Committee’ before summarizing what theoretical insights might be brought to bear and attempting to draw some provisional conclusions. Some evidence is presented suggesting there is a degree of tension and ambiguity between alterative models of multi-agency working

Is the Pale Blue Dot unique? Optimized photometric bands for identifying Earth-like exoplanets

The next generation of ground and space-based telescopes will image habitable planets around nearby stars. A growing literature describes how to characterize such planets with spectroscopy, but less consideration has been given to the usefulness of planet colors. Here, we investigate whether potentially Earth-like exoplanets could be identified using UV-visible-to-NIR wavelength broadband photometry (350-1000 nm). Specifically, we calculate optimal photometric bins for identifying an exo-Earth and distinguishing it from uninhabitable planets including both Solar System objects and model exoplanets. The color of some hypothetical exoplanets - particularly icy terrestrial worlds with thick atmospheres - is similar to Earth's because of Rayleigh scattering in the blue region of the spectrum. Nevertheless, subtle features in Earth's reflectance spectrum appear to be unique. In particular, Earth's reflectance spectrum has a 'U-shape' unlike all our hypothetical, uninhabitable planets. This shape is partly biogenic because O2-rich, oxidizing air is transparent to sunlight, allowing prominent Rayleigh scattering, while ozone absorbs visible light, creating the bottom of the 'U'. Whether such uniqueness has practical utility depends on observational noise. If observations are photon limited or dominated by astrophysical sources (zodiacal light or imperfect starlight suppression), then the use of broadband visible wavelength photometry to identify Earth twins has little practical advantage over obtaining detailed spectra. However, if observations are dominated by dark current then optimized photometry could greatly assist preliminary characterization. We also calculate the optimal photometric bins for identifying extrasolar Archean Earths, and find that the Archean Earth is more difficult to unambiguously identify than a modern Earth twin.Comment: 10 figures, 38 page

The evolution of solar flux from 0.1 nm to 160 μm : quantitative estimates for planetary studies

Understanding changes in the solar flux over geologic time is vital for understanding the evolution of planetary atmospheres because it affects atmospheric escape and chemistry, as well as climate. We describe a numerical parameterization for wavelength-dependent changes to the non-attenuated solar flux appropriate for most times and places in the solar system. We combine data from the Sun and solar analogs to estimate enhanced UV and X-ray fluxes for the young Sun and use standard solar models to estimate changing visible and infrared fluxes. The parameterization, a series of multipliers relative to the modern top of the atmosphere flux at Earth, is valid from 0.1 nm through the infrared, and from 0.6 Gyr through 6.7 Gyr, and is extended from the solar zero-age main sequence to 8.0 Gyr subject to additional uncertainties. The parameterization is applied to a representative modern day flux, providing quantitative estimates of the wavelength dependence of solar flux for paleodates relevant to the evolution of atmospheres in the solar system (or around other G-type stars). We validate the code by Monte Carlo analysis of uncertainties in stellar age and flux, and with comparisons to the solar proxies κ1 Cet and EK Dra. The model is applied to the computation of photolysis rates on the Archean Earth.Publisher PDFPeer reviewe

Anoxic atmospheres on Mars driven by volcanism : implications for past environments and life

This work was supported by NNX10AN67G grant from NASA's Mars Fundamental Research Program awarded to DCC.Mars today has no active volcanism and its atmosphere is oxidizing, dominated by the photochemistry of CO2 and H2O. Mars experienced widespread volcanism in the past and volcanic emissions should have included reducing gases, such as H2 and CO, as well as sulfur-bearing gases. Using a one-dimensional photochemical model, we consider whether plausible volcanic gas fluxes could have switched the redox-state of the past martian atmosphere to reducing conditions. In our model, the total quantity and proportions of volcanic gases depend on the water content, outgassing pressure, and oxygen fugacity of the source melt. We find that, with reasonable melt parameters, the past martian atmosphere (∼3.5 Gyr to present) could have easily reached reducing and anoxic conditions with modest levels of volcanism, >0.14 km3 yr−1, which are well within the range of estimates from thermal evolution models or photogeological studies. Counter-intuitively we also find that more reducing melts with lower oxygen fugacity require greater amounts of volcanism to switch a paleo-atmosphere from oxidizing to reducing. The reason is that sulfur is more stable in such melts and lower absolute fluxes of sulfur-bearing gases more than compensate for increases in the proportions of H2 and CO. These results imply that ancient Mars should have experienced periods with anoxic and reducing atmospheres even through the mid-Amazonian whenever volcanic outgassing was sustained at sufficient levels. Reducing anoxic conditions are potentially conducive to the synthesis of prebiotic organic compounds, such as amino acids, and are therefore relevant to the possibility of life on Mars. Also, anoxic reducing conditions should have influenced the type of minerals that were formed on the surface or deposited from the atmosphere. We suggest looking for elemental polysulfur (S8) as a signature of past reducing atmospheres. Finally, our models allow us to estimate the amount of volcanically sourced atmospheric sulfate deposited over Mars’ history, approximately ∼106-109 Tmol, with a spread depending on assumed outgassing rate history and magmatic source conditions.PostprintPeer reviewe

Conditional and Dissociation Mutants of pp60v-src: Tools for Dissecting Transformation and Mitogenesis

The biological and biochemical properties of ts LA32 Src were examined in established rat fibroblasts. A cell clone expressing this protein (Rati f32) was found to be markedly temperature sensitive for morphological transformation and anchorage-independent growth. Ratl f32 are rendered quiescent by serum deprivation at restrictive temperature; temperature shift in the absence of added serum factors results in cell cycle transit. The conditional nature of the biological phenotypes was not reflected in any examined biochemical parameter: tsLA32 Src elevated cellular phosphotyrosine at both restrictive and permissive temperatures, and was non-conditionally autophosphorylated. tsLA32 Src in vitro kinase activity was not measurable by immune-complex assay under conditions where thermolabile and wild-type controls behaved as expected, perhaps through lability of the mutant protein. Published data indicate that tsLA32 Src remains in the particulate fraction of CEF at restrictive temperature. These data suggest that in vivo enzyme activity, autophosphorylation and membrane localization are together insufficient for transformation of Ratl cells. Non-catalytic domains of pp60v-src and their possible roles in transformation are discussed. These properties suggest tsLA32 Src would be useful in defining early Src-responsive events. Preliminary results indicate that very few proteins become differentially labelled with 35S-methionine after temperature shift of quiescent Ratl f32. Dissociation of transformation parameters would allow dissection of these and other Src-responsive events. Dissociation was attempted using a thermolabile kinase defective for morphological transformation through point mutation of the N-terminal glycine. This non-myristylated protein, tsLA29A2 Src, retained thermolabile in vitro kinase properties but was somewhat toxic in Ratl cells. tsLA29A2 was non-mitogenic, and did not induce AP-1 binding activity in temperature-shifted quiescent CEF. Furthermore, tsLA29A2 Src was non-mitogenic in quiescent CEF under conditions where AP-1 activity was artificially elevated. These data suggest a need for membrane association in the induction of both AP-1 binding activity and other v-src-induced events required for mitogenesis

Micro-Pressure Sensors for Future Mars Missions

The joint research interchange effort was directed at the following principal areas: u further development of NASA-Ames' Mars Micro-meteorology mission concept as a viable NASA space mission especially with regard to the science and instrument specifications u interaction with the flight team from NASA's New Millennium 'Deep-Space 2' (DS-2) mission with regard to selection and design of micro-pressure sensors for Mars u further development of micro-pressure sensors suitable for Mars The research work undertaken in the course of the Joint Research Interchange should be placed in the context of an ongoing planetary exploration objective to characterize the climate system on Mars. In particular, a network of small probes globally-distributed on the surface of the planet has often been cited as the only way to address this particular science goal. A team from NASA Ames has proposed such a mission called the Micrometeorology mission, or 'Micro-met' for short. Surface pressure data are all that are required, in principle, to calculate the Martian atmospheric circulation, provided that simultaneous orbital measurements of the atmosphere are also obtained. Consequently, in the proposed Micro-met mission a large number of landers would measure barometric pressure at various locations around Mars, each equipped with a micro-pressure sensor. Much of the time on the JRI was therefore spent working with the engineers and scientists concerned with Micro-met to develop this particular mission concept into a more realistic proposition