The status of the world's public-domain digital topography of the land and ice

There has been no reasonably comprehensive survey of what digital, elevation models of the Earth's land surface exist in the public‐domain. We have performed a survey of these data, and we report on the coverage and cost of the data we have established. To qualify for inclusion in our coverage, we required the data to be available to the general public, obtainable from a specific, identified institution, and to have a determined cost. We have established that at 100 m resolution coverage exists of most of the the developed world. In the United States and Australia, the data are available at cost, at around 3000 km^{2} £^{-1}. In the remaining countries, the data are available from mapping agencies with varying commercial pricing strategies. The total cost of the data we have identified is £ 1,688,312. For much of the world we are unable to confirm the existence of such data, and our experience is that in these regions it will prove difficult to obtain digital, elevation data, if, indeed, it exists at all

Controls on ERS altimeter measurements over ice sheets: Footprint-scale topography, backscatter fluctuations, and the dependence of microwave penetration depth on satellite orientation

We consider the reliability of radar altimeter measurements of ice sheet elevation and snowpack properties in the presence of surface undulations. We demonstrate that over ice sheets the common practice of averaging echoes by aligning the first return from the surface at the origin can result in a redistribution of power to later times in the average echo, mimicking the effects of microwave penetration into the snowpack. Algorithms that assume the topography affects the radar echo shape in the same way that waves affect altimeter echoes over the ocean will therefore lead to biased estimates of elevation. This assumption will also cause errors in the retrieval of echo-shape parameters intended to quantify the penetration of the microwave pulse into the snowpack. Using numerical simulations, we estimate the errors in retrievals of extinction coefficient, surface backscatter, and volume backscatter for various undulating topographies. In the flatter portions of the Antarctic plateau, useful estimates of these parameters may be recovered by averaging altimeter echoes recorded by the European Remote Sensing satellite (ERS-1). By numerical deconvolution of the average echoes we resolve the depths in the snowpack at which temporal changes and satellite travel-direction effects occur, both of which have the potential to corrupt measurements of ice sheet elevation change. The temporal changes are isolated in the surface-backscatter cross section, while directional effects are confined to the extinction coefficient and are stable from year to year. This allows the removal of the directional effect from measurement of ice-sheet elevation change

Inland thinning of the Amundsen Sea sector, West Antarctica

[1] Together with the Pine Island glacier (PIG), the Thwaites (TG) and Smith (SG) glaciers are the principal drainage systems of the Amundsen Sea (AS) sector of Western Antarctica. Here we use satellite radar altimetry and interferometry to show that a rapid thinning of ice has occurred within the fastest flowing sections of all AS outlet glaciers. The pattern of thinning extends to distances greater than 150 km inland. Between 1991 and 2001, the TG and SG thinned by more than 25 and 45 m at their grounding lines, and a total of 154 +/- 16 km(3) of ice (or 0.43 mm of eustatic sea level rise) was lost from the AS sector glaciers to the ocean. We show that the thickness changes may have caused the PIG, TG, and SG to retreat inland by over 8, 4, and 7 km respectively, in line with independent estimates of grounding line migration

Attitude and behaviour dichotomy in SME strategic alliance: A south west of Western Australian study

Strategic alliances are generally perceived as cooperative relationships constrained within the parameters of bounded rationality, seeking to maximise their levels of control in a turbulent economic environment. They are also commonly conceptualised as a means of creating competitive advantage in business. In regional areas of Western Australia they are favoured by government instrumentalities as a means of making small to medium enterprises (SMEs) more competitive. With the dominant global emphasis in the literature on big business, relatively little is known still about strategic alliances in small to medium enterprises. Moreover, the research on strategic alliances within Australia s also limited, and since 92 %or businesses in Australia arc SMEs (ABS 1999), there are significant gaps in the literature about a significant contributor to economic health or the nation. For these reasons this thesis focuses attention on SMEs in Australia, in particular the South West of Western Australia. This thesis is concerned with strategic alliance propensity in selected small to medium enterprises with less than 500 employees but three or more employees including family members. Mixed methodology data collection was used; based on an extensively validated international survey instrument, and a series of in-depth interviews. The outcome of the study was a synthesised model of SME strategic alliance decision-making which addresses the impacts on attitudes of SME Key Decision-Leaders choosing either positive or negative behaviours relating to strategic alliance formation. The development of this model, the Strategic Alliance Participation Paradigm (SAPP) was achieved through an iterative approach to environmental exploration, literature scanning and analysis and the application of a mixed methodological approach to data collection. Chapters One to Three present the development of the research questions and the research process adopted to address important elements or the research. Chapter Four presents the major consolidated findings based on factor analysed outcomes. Variables were subjected to logistic regression statistical analysis determining support for hypothesised research outcomes. In depth interviews provide evidence of the SME domain, in the context initially of the regional area under review. Conclusions arc further reviewed in the context or a recent significant Norwegian culturally based survey. The Strategic Alliance Participation Paradigm reflects the work carried out by a small group of earlier researchers, and further, empirically tests the determinants of SME Key-Decision-Leader strategic alliance behaviour. Recommendations for future research developed from the research findings arc presented in Chapter Five supporting the conclusions und implications of this study for future SME strategic alliance research both regional and global. Benefits from this process will be seen in the enhanced ability to benchmark at source regional differences and similarities, and thereby to further enhance the value of the outcomes to scholars and practitioners. Researchers could do well to pursue understanding of identified gaps in knowledge and to cooperate with industry to enhance alliance behaviour, achieving benefits through philosophy of competitive tendering. Significant within the outcomes however, was the identified need to research ways to support and grow the large sector of Australian business, the small to medium enterprise

Targeted activation of dendritic cells via the CD40 receptor

Dendritic cell (DC) activation underpins the patient immune response in multiple cancers, including ovarian cancer. While DCs are detected within the margins of ovarian tumours, DC populations are maintained in an immature state, displaying low levels of co-stimulatory receptor expression and cytokine production, with impaired antigen presentation capacity.Engagement of the DC surface receptor CD40 (CD40R) is required for efficient immune activation. This thesis investigated the potential of a Monovalent Targeted Peptide targeting CD40R (MTP40) to bind the CD40R of a murine DC cell line (tsDC), and whether the interaction could be enhanced by multivalent presentation.This work aimed to demonstrate the suitability of two potential scaffolds for multivalent presentation. The first system investigated the activity of MTP40 presented on streptavidin as a tetramer (Tet40), which improved the binding kinetics of MTP40 (KD 1.32μM) when presented as Tet40 (KD 0.072μM). Binding capacity was confirmed as MTP40 conjugated to streptavidin Dynabeads successfully isolated the CD40R by pull down assay. The second system explored MTP40 attached to the surface of gold nanoparticles through thiol-Au bonds, to produce targeted polyvalent gold nanoparticles (TPN40) presenting up to 2000 peptide units per molecule, which demonstrated binding to CD40R by coomassie stain.Changes in outputs associated with tsDC activation were observed in response to CD40R targeted treatments. Surface expression of CD40R was upregulated in response to Tet40 or TPN40, while TPN40 induced increased expression of activating receptors CD86 and CD54. tsDC upregulated expression of IL-2 and IL-12, with a corresponding down-regulation of IL-10, in response to Tet40 or TPN40. TPN40 treatments also stimulated uptake of the model antigen FITC-Ova by tsDC.After confirming the tsDC cell line induced functional changes in response to CD40R targeted activation, second goal was to determine whether the “activated” tsDCs were able to induce priming of effector T cells in an antigen specific manner. T cell lines significantly upregulated production of IL-2 and IL-12 in response to TPN40, while the cytotoxic T cell line specifically upregulated IFN-. T cell induced cytotoxicity and proliferation were not significantly affected by the addition of ID8 tumour cell lysates, suggesting further optimizations are needed to produce an antigen-specific response.This study provided evidence that multivalent engagement of CD40R is required to induce effective tsDC maturation, highlighting the importance of ligand presentation in immunity. The work also provides a multistep model of immune activation as stimulated tsDCs were capable of inducing changes in T cell lines. This demonstrates proof-of-principle that multivalent activation at the DC level is sufficient to prime an effector T cell response.These conclusions have wider significance in the field of immunology, where they suggest multivalent interactions can produce optimised immune responses. Gold nanoparticles provided a stable, well-tolerated platform for multivalent drug delivery. Future work should investigate the bimodal application of gold nanoparticles for targeted drug delivery with tumour imaging

Spatial and temporal evolution of Pine Island Glacier thinning, 1995-2006

We use ERS-2 and ENVISAT satellite radar altimetry to examine spatial and temporal changes in the rate of thinning of the Pine Island Glacier, West Antarctica, during the period 1995 to 2006. We show that the pattern of thinning has both accelerated and spread inland to encompass tributaries flowing into the central trunk of the glacier. Within the 5,400 km(2) central trunk, the average rate of volume loss quadrupled from 2.6 +/- 0.3 km(3) yr(-1) in 1995 to 10.1 +/- 0.3 km(3) yr(-1) in 2006. The region of lightly grounded ice at the glacier terminus is extending upstream, and the changes inland are consistent with the effects of a prolonged disturbance to the ice flow, such as the effects of ocean- driven melting. If the acceleration continues at its present rate, the main trunk of PIG will be afloat within some 100 years, six times sooner than anticipated. Citation: Wingham, D.J., D.W. Wallis, and A. Shepherd (2009), Spatial and temporal evolution of Pine Island Glacier thinning, 1995-2006, Geophys. Res. Lett., 36, L17501, doi: 10.1029/2009GL039126

Bed topography and marine ice-sheet stability

This paper examines the effect of basal topography and strength on the grounding-line position, flux and stability of rapidly-sliding ice streams. It does so by supposing that the buoyancy of the ice stream is small, and of the same order as the longitudinal stress gradient. Making this scaling assumption makes the role of the basal gradient and accumulation rate explicit in the lowest order expression for the ice flux at the grounding line and also provides the transcendental equation for the grounding-line position. It also introduces into the stability condition terms in the basal curvature and accumulation-rate gradient. These expressions revert to well-established expressions in circumstances in which the thickness gradient is large at the grounding line, a result which is shown to be the consequence of the non-linearity of the flow. The behaviour of the grounding-line flux is illustrated for a range of bed topographies and strengths. We show that, when bed topography at a horizontal scale of several tens of ice thicknesses is present, the grounding-line flux and stability have more complex dependencies on bed gradient than that associated with the ‘marine ice-sheet instability hypothesis’, and that unstable grounding-line positions can occur on prograde beds as well as stable positions on retrograde beds