For over twenty-five years, the International Global Navigation Satellite System (GNSS) Service (IGS) has carried out its mission to advocate for and provide freely and openly available high-precision GNSS data and products. The IGS is an essential component of the IAG’s Global Geodetic Observing System (GGOS), where it facilitates cost-effective geometrical linkages with and among other precise geodetic observing techniques, including: Satellite Laser Ranging (SLR), Very Long Baseline Interferometry (VLBI), and Doppler Orbitography and Radio Positioning Integrated by Satellite (DORIS). These linkages are fundamental to generating and accessing the International Terrestrial Reference Frame (ITRF). As it enters its second quarter-century, the IGS is evolving into a truly multi-GNSS service, and at its heart is a strong culture of sharing expertise, infrastructure, and other resources for the purpose of encouraging global best practices for developing and delivering GNSS data and products all over the world. This poster will present an update on current IGS products and operations, as well as highlights on recent organizational developments and community activities. The impacts and benefits of global cooperation and openly available data will be emphasized, and information about the IGS stations and network, contributions to the International Terrestrial Reference Frame solutions, and product applications will be presented. A summary of IGS products, with emphasis on analysis, coordination, applications, and their availability will be described. Information about efforts to form new groups supporting product generation within IGS open data and product policies will be included. Information about the themes and topics of discussion for the upcoming 2020 IGS Workshop in Boulder, Colorado, USA will also be provided.

Role of the Bureau: To advocate and encourage implementation of the Core and Co-location Network to satisfy GGOS requirements, to monitor the status of the network and project its future condition, and to support and advocate for infrastructure critical for the development of data products essential to GGOS.

Understanding how the mechanical properties of cells alter with disease may help with the development of novel diagnostics and treatment regimes. The emergence of tools such as the atomic force microscope (AFM) has enabled us to physically measure the mechanical properties of cells. However, suitable models for the analysis of real experimental data are either absent, or fail to provide a simple analysis tool in which experimental data can be analyzed quickly and reliably. The Hertz model has been widely used to study AFM data on living cells, however it makes assumptions that are untrue for cells, namely that cells behave as linear elastic bodies. This article presents and evaluates an alternative nonlinear Hertz model, which allows the Young's modulus to vary according to a second order polynomial function of indentation depth. Evaluation of the model revealed that prostate cancer cells (PC3) responded more uniformly to force compared to the normal PNT2 cells. Also, more energy ( J ) was needed to deform the normal prostate cells compared to the prostate cancer cells. Finally, the model described here suggests that overall the normal prostate cells behave in a more linear fashion to applied force compared to the prostate cancer cells. Microsc. Res. Tech., 2013. © 2012 Wiley Periodicals, Inc.

In an absolute sense, AUSGeoid09 is an order of magnitude more accurate than AUSGeoid98 at converting ellipsoidal heights to Australian Height Datum (AHD) heights and vice versa. Results of this study show AUSGeoid09 can be used to compute AHD heights from Global Navigation Satellite System (GNSS) ellipsoidal heights with an uncertainty of less than ±0.03 m (one sigma). The improvement is largely due to the inclusion of a geometric component in AUSGeoid09 that accounts for the spatially varying offset between a gravimetric quasigeoid model and the AHD. This geometric component was calculated using least squares collocation in cross validation mode and then added to the gravimetric quasigeoid. Although previous AUSGeoid models were used to convert GNSS ellipsoidal heights to the AHD and vice versa, none until now have accounted for the gravimetric quasigeoid to AHD offsets. This offset is a consequence of how the AHD was realised and has commonly resulted in misfits of ∼0.5 m or more. When used with GNSS technology, AUSGeoid09 can replace the need for traditional third-order levelling (Class LC; 12 ) in many situations. Relative tests of AUSGeoid09 over a continent-wide set of over 20 million baselines showed that it can deliver better than Class LC tolerances in 99 percent of cases. The model accepts a user's GDA94 latitude, longitude and ellipsoidal height and returns an AHD height and deviations of the vertical. AUSGeoid09 is now available free-of-charge on the Geoscience Australia website ( http://www.ga.gov.au/geodesy/ausgeoid/nvalcomp.jsp).

An investigation into orientation preferences shown by actin fibres within ex-situ actin as imaged by Atomic Force Microscopy (AFM) is described. Actin is a primary cytoskeletal component and is believed to play a vital role in cell structure. Actin structure images measured by AFM were analysed using automated pre-processing steps. These steps were identical for the production of an initial binary image, which was then processed by both Hough transformation and thinning. Results obtained question the validity of using the Hough transform approach, as bias could not easily be eliminated, and hence the Hough transform method was deemed to be unsuitable for this application and instead the thinning technique was used to identify and locate actin orientation within the AFM images. The results show that polymerised ex-situ actin fibres appears to display a bimodal distribution of orientation, with a 90 degree separation, with a significant co-efficient of bimodality of 0.656.

All atomic force microscope (AFM) images suffer from distortions, which are principally produced by the interaction between the measured sample and the AFM tip. If the three-dimensional shape of the tip is known, the distorted image can be processed and the original surface form `restored', typically by deconvolution approaches. This restored image gives a better representation of the real 3D surface of the measured sample than the original distorted image. In this paper, we propose a method for estimating the three-dimensional shape of the AFM tip by measuring a micro-cylinder with a-priori known dimensions. The estimated tip shape is then used to restore subsequent AFM images, when measured with the same tip, under similar measurement conditions. Significantly, the impulse response of the AFM can be deduced using this method. The suitability of this novel approach for restoring AFM images has been confirmed using both computer simulation and also with real experimental AFM images. The proposed method is compared with standard restoration techniques and is shown to provide superior performance to such approaches.

SUMMARY Global Navigation Satellite Systems (GNSSs) involve satellites, ground stations and user equipment, and are now used to support many activities within modern societies. Among them, precise positioning for geodetic, surveying and critical real-time machine guidance applications requires a substantial investment in ground infrastructure in the form of continuously operating reference stations (CORS) and associated ICT components. The federal government, state governments and the government of New Zealand are currently establishing CORS networks to address several precise positioning 'markets'. The foundation infrastructure in Australia is funded under the AuScope initiative and, together with other geodetic CORS will by mid-2011 see well over 250 stable CORS across Australia and New Zealand to support national datum and global geodesy goals. The latter include support for the International GNSS Service (IGS) and the Global Geodetic Observing System (GGOS). The Global Positioning System (GPS) from the U.S. is the best known, and only currently fully operational, GNSS. Russia has deployed its own GNSS called GLONASS which will be fully operational within one or two years. Fuelling growth in precise positioning applications during the next decade will be next generation GNSSs that are currently being developed and deployed, these include the U.S.'s modernised GPS-IIF and planned GPS-III, the revitalised (and later to be modernised) GLONASS, Europe's planned GALILEO system, and China's COMPASS system. Furthermore, a number of Space Based Augmentation Systems (SBASs) and Regional Navigation Satellite Systems (RNSSs) will add extra satellites and signals to the multi-constellation GNSS/RNSS 'mix'. This paper explores some of the implications of next generation GNSS from the perspective of precise positioning. In particular, issues such as the different "tiers" of CORS, unification of CORS infrastructure, capabilities of the next generation CORS receiver, and deployment strategies for future CORS will be discussed.

AUSGeoid09 is the new Australia-wide gravimetric quasigeoid model that has been a posteriori fitted to the Australian Height Datum (AHD) so as to provide a product that is practically useful for the more direct determination of AHD heights from Global Navigation Satellite Systems (GNSS). This approach is necessary because the AHD is predominantly a third-order vertical datum that contains a ~1 m north-south tilt and ~0.5 m regional distortions with respect to the quasigeoid, meaning that GNSS-gravimetric-quasigeoid and AHD heights are inconsistent. Because the AHD remains the official vertical datum in Australia, it is necessary to provide GNSS users with effective means of recovering AHD heights. The gravimetric component of the quasigeoid model was computed using a hybrid of the remove-compute-restore technique with a degree-40 deterministically modified kernel over a one-degree spherical cap, which is superior to the remove-compute-restore technique alone in Australia (with or without a cap). This is because the modified kernel and cap combine to filter long-wavelength errors from the terrestrial gravity anomalies. The zero-tide EGM2008 global gravitational model to degree 2,190 was used as the reference field. Other input data are ~1.4 million land gravity anomalies from Geoscience Australia, 1′ × 1′ DNSC2008GRA altimeter-derived gravity anomalies offshore, the 9′′ × 9′′ GEODATA-DEM9S Australian digital elevation model, and a readjustment of Australian National Levelling Network (ANLN) constrained to the CARS2006 mean dynamic ocean topography model. To determine the numerical integration parameters for the modified kernel, the gravimetric component of AUSGeoid09 was compared with 911 GNSS-observed ellipsoidal heights at benchmarks. The standard deviation of fit to the GNSS-AHD heights is ±222 mm, which dropped to ±134 mm for the readjusted GNSS-ANLN heights showing that careful consideration now needs to be given to the quality of the levelling data used to assess gravimetric quasigeoid models. The publicly released version of AUSGeoid09 also includes a geometric component that models the difference between the gravimetric quasigeoid and the zero surface of the AHD at 6,794 benchmarks. This a posteriori fitting used least-squares collocation (LSC) in cross-validation mode to determine a correlation length of 75 km for the analytical covariance function, whereas the noise was taken from the estimated standard deviation of the GNSS ellipsoidal heights. After this LSC surface fitting, the standard deviation of fit reduced to ±30 mm, one-third of which is attributable to the uncertainty in the GNSS ellipsoidal heights.

In November 2006, the Australian Federal Government announced AUS$15.8M in funding for geospatial research infrastructure through the National Collaborative Research Infrastructure Strategy (NCRIS). Funded within a broader capability area titled Structure and Evolution of the Australian Continent, NCRIS has provided a significant investment across Earth imaging, geochemistry, numerical simulation and modelling, the development of a virtual core library, and geospatial infrastructure. Known collectively as AuScope (www.auscope.org.au), this capability area has brought together Australian=92s leading Earth scientists to decide upon the most pressing scientific issues and infrastructure needs for studying Earth systems and their impact on the Australian continent. Importantly and at the same time, the investment in geospatial infrastructure offers the opportunity to raise Australian geodetic science capability to the highest international level into the future. The geospatial component of AuScope builds onto the AUS$15.8M of direct funding through the NCRIS process with significant in-kind and co-investment from universities and State/Territory and Federal government departments. The infrastructure to be acquired includes an FG5 absolute gravimeter, three gPhone relative gravimeters, three 12.1 m radio telescopes for geodetic VLBI, a continent-wide network of continuously operating geodetic quality GNSS receivers, a trial of a mobile SLR system and access to updated cluster computing facilities. We present an overview of the AuScope geospatial capability, review the current status of the infrastructure procurement and discuss some examples of the scientific research that will utilise the new geospatial infrastructure.

AuScope is an initiative established under the National Collaboration Research Infrastructure Strategy (NCRIS) to characterise the structure and evolution of the Australian continent. AuScope includes a Geospatial component that will enhance the accuracy and resolution of the National Geospatial Reference System including its temporal variability. This will have a direct impact on the many fields of science and industry that require accurate positioning to improve effectiveness. Ultimately it will also significantly improve the way geospatial data sets can be integrated. AuScope Geospatial will complement the other geoscience elements of AuScope by providing contemporary estimates of continental deformations including those resulting from plate tectonics stresses and anthropogenic (or human induced) causes. Knowledge of the deformation of the continent will lead to improved assessments of the state of stress of the continental crust and earthquake risk. This supports the development of improved risk mitigation procedures and updating of building codes. The improved understanding of the deformation of the continent will also assist studies of landscape evolution, research into soil types (agriculture) and salinity (land degradation). Geoscience Australia is working collaboratively with the Australian National University, University of Tasmania, Curtin University, and all of the state and territory governments to implement this program over four years to 2011. AuScope Geospatial will upgrade the ground infrastructure in all four key geodetic areas through:

In November 2006, the Australian Federal Government announced $15.8M in funding for geospatial research infrastructure through the National Collaborative Research Infrastructure Strategy (NCRIS). NCRIS is an initiative under the Australian Government's Backing Australia's Ability package with a number of key principles, including maximising the contributions of the R&D system to economic development, national security, social wellbeing and environmental sustainability. Here we outline why particular components of geospatial infrastructure are required in Australia to advance (equip) geospatial research over the next 20 years. We describe some of the scientific objectives that required an upgrade and densification of Australia's geospatial infrastructure. This paper is the perspective from a subset of University researchers involved in the AuScope Geospatial component, and so does riot necessarily encompass the opinions of all I hose involved in AuScope Geospatial.

We assess the accuracy of some indirect approaches to invariant point (IVP), or system reference point, determination of satellite laser ranging (SLR) and very long baseline interferometry (VLBI) systems using both observed and simulated survey data sets. Indirect IVP determination involves the observation of targets located on these systems during specific rotational sequences and by application of geometrical models that describe the target motion during these sequences. Of concern is that most SLR and VLBI systems have limited rotational freedom thereby placing constraint on the reliability of parameter estimation, including the IVP position. We assess two current approaches to IVP analysis using survey data observed at the Yarragadee (Australia) SLR and the Medicina (Italy) VLBI sites and also simulated data of a large rotationally constrained (azimuth-elevation) VLBI system. To improve reliability we introduce and assess some new geometric conditions, including inter-axis, inter-circle and inter-target conditions, to existing IVP analysis strategies. The error component of a local tie specifically associated with the indirect determination of SLR and VLBI IVP is less than 0.5 mm. For systems with significant rotational limits we find that the inter-axis and inter-circle conditions are critical to the computation of unbiased IVP coordinates at the sub-millimetre level. When the inter-axis and inter-circle geometric conditions are not imposed, we retrieve biased vertical coordinates of the IVP (in our simulated VLBI system) in the range of 1.2–3.4 mm. Using the new geometric conditions we also find that the axis-offset estimates can be recovered at the sub- millimetre accuracy (0.5 mm).

The development of multi-technique International Terrestrial Reference Frames such as ITRF2000 (Altamimi, 2002) has focussed attention on the need to precisely measure and express the local terrestrial connection between each of the complimentary space geodetic observation systems, such as GPS, GLONASS, SLR, VLBI and DORIS, at co-located geodetic observatories. Somewhat complicating this endeavour has been the difficulty of defining and measuring the relationship between the measurement reference points for each of the techniques. This is particularly the case for the SLR and VLBI observing systems where the reference point, sometimes referred to as the invariant reference point (IVP), is in general not able to be directly observed.