Titel Deelnemers "Korte inhoud" "Brief communication: Measuring and modelling the ice thickness of the Grigoriev ice cap (Kyrgyzstan) and comparison with global datasets" "Lander Van Tricht, Chloë Paice, Oleg Rybak, Philippe Huybrechts" "An accurate ice thickness distribution is crucial for correct projections of the future state of an ice mass. However, measuring the ice thickness with an in situ system is time-consuming and not scalable. Therefore, models have been developed to estimate the ice thickness without direct measurements. In this study, we reconstruct the ice thickness of the Grigoriev ice cap, Kyrgyzstan, from in situ observations and the yield stress method. We compare the results with data from six global ice thickness datasets composed without the use of our local measurements. The results highlight the limitations of these generic datasets primarily stemming from the subdivision of ice caps into distinct glaciers, the adoption of a (calibrated) creep parameter value, assumptions regarding ice mass flux, and errors regarding surface velocity observations. These shortcomings emphasize the importance of integrating local observations to calibrate models to achieve precise representations of ice thickness, particularly when dealing with smaller or slow-flowing cold ice caps, such as the Grigoriev ice cap." "On-site geometrical measurements of an experimental ice composite shell through TLS and photogrammetry" "Greet Deruyter, Hanne Glas, Jan Belis" "Measurement techniques for determining the thickness and shape of ice structures can be divided into contact and non-contact methods. The non-contact methods are the most appropriate for measuring relatively thin fiber reinforced ice shells because they hold no risk for damages. Furthermore, these measurement techniques can be repeated during the icing process, which, additionally, enables to produce intermediate results. This paper describes the 3D measurement and modelling methods used for the U+201CCandela pavilionU+201D that was built by university students and staff in the framework of an international project in Juuka, Finland during the winter of early 2016." "Thickness and composition measurements of nanoelectronics multilayer thin films by energy dispersive spectroscopy (EDS)" "Matthieu Gilbert, Wilfried Vandervorst" "Scaling is one of the main aspects to continuously improve the performance of nanoelectronic devices. This leads to increasingly more complex stacks including new materials; for example SiO2 is being replaced by high-k materials for gate dielectric applications and metal gates are introduced in place of poly-Si. Moreover, a change in the type of substrate is also considered; Ge and III/V materials are intensively investigated as possible candidates for Si substrate replacement. The introduction of these new materials together with the device downscaling has drastically increased the demand for both composition and thickness metrology methods. Various established techniques providing composition analysis exist such as X-Ray Photoelectron Spectroscopy (XPS) and Rutherford Backscattering Spectrometry (RBS), however, they usually require a large area for the analysis, complex instrumentation and can be time consuming. In this paper, Energy Dispersive Spectroscopy (EDS) coupled to Scanning Electron Microscopy (SEM) is used to determine both composition and thickness of simple and more complex multilayered thin films. The use of EDS for thickness measurements in small scale areas is also investigated." "Skin thickness measurements for optimal intradermal injections in children" "Timothi Van Mulder, Dieter Van Nuffel, Marc Demolder, Guido De Meyer, S. Moens, K.C.L. Beyers, Vanessa Vankerckhoven, Pierre Van Damme, Heidi Theeten" "Background In the context of precision medicine and in response to the highly needed capacity of rapid interventions towards new infectious diseases and pandemic outbreaks, intradermal immunization is gaining increased attention. However, the currently used Mantoux technique for ID injection is difficult to standardize and requires training, especially when used in children. To allow determining the maximum penetration depth and needle characteristics for the development of a platform of medical devices suited for intradermal injection, VAX-ID® and to ensure an accurate ID injection in children, the epidermal and dermal thickness at the proximal ventral and dorsal forearm (PVF & PDF) and at the deltoid region in children aged 8 weeks to 18 years were assessed. The lateral part of the upper leg was assessed as well in children aged 8 weeks to 2 years since it is a commonly used injection site in this population. Materials & Methods Mean thickness of the PVF, PDF, lateral part of the upper leg and deltoid were measured using high-frequency ultrasound. Association with gender, age and BMI was assessed using Mann-Whitney U Test, Spearman correlation and Wilcoxon Signed Ranks Test, respectively. Results Results showed an overall mean skin thickness of 0.99 mm (SD: 0.14 mm) at the PVF, 1.20 mm (SD: 0.17) at the PDF, 1.28 mm (SD: 0.16) at the lateral part of the upper leg and increasing to 1.32 mm (0.25) at the deltoid region. Age and BMI correlated significantly (p " "Mass budget of the grounded ice in Lambert Glacier-Amery Ice Shelf system" "Jiahong Wen, Yafeng Wang, Jiying Liu, Kenneth Jezek, Beata Csatho, Katy Farness, Bo Sun" "We used remote-sensing and in situ measurements of surface accumulation rate, ice surface velocity, thickness and elevation to evaluate the mass budgets of grounded ice-flow regimes that form the Lambert Glacier-Amery Ice Shelf system. Three distinct drainage regimes are considered: the western and eastern margins of the ice shelf, and the southern grounding line at the major outlet glacier confluence, which can be identified with drainage zones 9, 11 and 10 respectively of Giovinetto and Zwally (2000). Our findings show the entire grounded portion of the basin is approximately in balance, with a mass budget of -4.2_9.8 Gt a-1. Drainages 9, 10 and 11 are within balance to the level of our measurement uncertainty, with mass budgets of -2.5_2.8 Gt a-1, -2.6_7.8 Gt a-1 and 0.9_2.3 Gt a-1, respectively. The region upstream of the Australian Lambert Glacier basin (LGB) traverse has a net mass budget of 4.4_6.3 Gt a-1, while the downstream region has -8.9_9.9 Gt a-1. These results indicate that glacier drainages 9, 10 and 11, upstream and downstream of the Australian LGB traverse, are in balance to within our measurement error." "Mass budget of the grounded ice in the Lambert Glacier-Amery Ice Shelf system" "Philippe Huybrechts" "We used remote-sensing and in situ measurements of surface accumulation rate, ice surface velocity, thickness and elevation to evaluate the mass budgets of grounded ice-flow regimes that form the Lambert Glacier-Amery Ice Shelf system. Three distinct drainage regimes are considered: the western and eastern margins of the ice shelf, and the southern grounding line at the major outlet glacier confluence, which can be identified with drainage zones 9, 11 and 10 respectively of Giovinetto and Zwally (2000). Our findings show the entire grounded portion of the basin is approximately in balance, with a mass budget of -4.2±9.8 Gta-1. Drainages 9, 10 and 11 are within balance to the level of our measurement uncertainty, with mass budgets of -2.5 ± 2.8 Gta-1, -2.6 ± 7.8 Gta-1 and 0.9 ± 2.3 Gta-1, respectively. The region upstream of the Australian Lambert Glacier basin (LGB) traverse has a net mass budget of 4.4 ± 6.3 Gta-1, while the downstream region has -8.9 ± 9.9 Gta-1. These results indicate that glacier drainages 9, 10 and 11, upstream and downstream of the Australian LGB traverse, are in balance to within our measurement error." "Thermal regime of the Grigoriev ice cap and the Sary-Tor glacier in the inner Tien Shan, Kyrgyzstan" "Lander Van Tricht, Philippe Huybrechts" "The thermal regime of glaciers and ice caps represents the internal distribution of ice temperatures. An accurate knowledge of the thermal regime of glaciers and ice caps is important to understand their dynamics and response to climate change and to model their evolution. Although the assumption is that most ice masses in the Tien Shan are polythermal, this has not been examined in appropriate detail so far. In this research, we investigate the thermal regime of the Grigoriev ice cap and the Sary-Tor glacier, both located in the inner Tien Shan in Kyrgyzstan, using a 3D higher-order thermomechanical ice flow model. Input data and boundary conditions are inferred from a surface energy mass balance model, a historical air temperature and precipitation series, ice thickness measurements and reconstructions, and digital elevation models. Calibration and validation of the englacial temperatures are performed using historical borehole measurements on the Grigoriev ice cap and radar measurements for the Sary-Tor glacier. The results of this study reveal a polythermal structure of the Sary-Tor glacier and a cold structure of the Grigoriev ice cap. The difference is related to the larger amount of snow (insulation) and refreezing meltwater (release of latent heat) for the Sary-Tor glacier, resulting in higher surface layer temperature, especially in the accumulation area, which is subsequently advected downstream. Further, ice velocities are much lower for the Grigoriev ice cap, with consequent lower horizontal advection rates. A detailed analysis concerning the influence of temperature and precipitation changes at the surface reveals that the thermal structure of both ice bodies is not constant over time, with recent climate change causing increasing ice temperatures in higher areas. The selected ice masses are representative examples of the (inner) Tien Shan glaciers and ice caps. Therefore, our findings and the calibrated parameters can be generalised, allowing improved understanding of the dynamics and future evolution of other glaciers and ice caps in the region." "High turnover rates indicated by changes in the fixed N forms and their stable isotopes in Antarctic landfast sea ice" "François Fripiat, Daniel M. Sigman, Guillaume Massé, Jean-Louis Tison" "We report concentration and nitrogen and oxygen isotopic measurements of nitrate, total dissolved nitrogen, and particulate nitrogen from Antarctic landfast sea ice, covering almost the complete seasonal cycle of sea ice growth and decay (from April to November). When sea ice forms in autumn, ice algae growth depletes nitrate and accumulates organic N within the ice. Subsequent low biological activity in winter imposes minor variations in the partitioning of fixed N. In early spring, the coupling between nitrate assimilation and brine convection at the sea ice bottom traps a large amount of fixed N within sea ice, up to 20 times higher than in the underlying seawater. At this time, remineralization and nitrification also accelerate, yielding nitrate concentrations up to 5 times higher than in seawater. Nitrate δ15N and δ18O are both elevated, indicating a near-balance between nitrification and nitrate assimilation. These findings require high microbially mediated turnover rates for the large fixed N pools, including nitrate. When sea ice warms in the spring, ice algae grow through the full thickness of the ice. The warming stratifies the brine network, which limits the exchange with seawater, causing the once-elevated nitrate pool to be nearly completely depleted. The nitrate isotope data point to light limitation at the base of landfast ice as a central characteristic of the environment, affecting its N cycling (e.g., allowing for nitrification) and impacting algal physiology (e.g., as reflected in the N and O isotope effects of nitrate assimilation)." "Ice core evidence for a 20th century increase in surface mass balance in coastal Dronning Maud Land, East Antarctica" "B. Hubbard, Jan T. M. Lenaerts, Reinhard Drews, Kevin De Bondt, Philippe Claeys" "Ice cores provide temporal records of surface mass balance (SMB). Coastal areas of Antarctica have relatively high and variable SMB, but are under-represented in records spanning more than 100 years. Here we present SMB reconstruction from a 120 m-long ice core drilled in 2012 on the Derwael Ice Rise, coastal Dronning Maud Land, East Antarctica. Water stable isotope (δ18O and δD) stratigraphy is supplemented by discontinuous major ion profiles and continuous electrical conductivity measurements. The base of the ice core is dated to AD 1759 ± 16, providing a climate proxy for the past  ∼ 250 years. The core's annual layer thickness history is combined with its gravimetric density profile to reconstruct the site's SMB history, corrected for the influence of ice deformation. The mean SMB for the core's entire history is 0.47 ± 0.02 m water equivalent (w.e.) a−1. The time series of reconstructed annual SMB shows high variability, but a general increase beginning in the 20th century. This increase is particularly marked during the last 50 years (1962–2011), which yields mean SMB of 0.61 ± 0.01 m w.e. a−1. This trend is compared with other reported SMB data in Antarctica, generally showing a high spatial variability. Output of the fully coupled Community Earth System Model (CESM) suggests that, although atmospheric circulation is the main factor influencing SMB, variability in sea surface temperatures and sea ice cover in the precipitation source region also explain part of the variability in SMB. Local snow redistribution can also influence interannual variability but is unlikely to influence long-term trends significantly. This is the first record from a coastal ice core in East Antarctica to show an increase in SMB beginning in the early 20th century and particularly marked during the last 50 years." "Technical Note: Cortical thickness and density estimation from clinical CT using a prior thickness-density relationship" "Harry van Lenthe" "PURPOSE: Cortical thickness and density are critical components in determining the strength of bony structures. Computed tomography (CT) is one possible modality for analyzing the cortex in 3D. In this paper, a model-based approach for measuring the cortical bone thickness and density from clinical CT images is proposed. METHODS: Density variations across the cortex were modeled as a function of the cortical thickness and density, location of the cortex, density of surrounding tissues, and imaging blur. High resolution micro-CT data of cadaver proximal femurs were analyzed to determine a relationship between cortical thickness and density. This thickness-density relationship was used as prior information to be incorporated in the model to obtain accurate measurements of cortical thickness and density from clinical CT volumes. The method was validated using micro-CT scans of 23 cadaver proximal femurs. Simulated clinical CT images with different voxel sizes were generated from the micro-CT data. Cortical thickness and density were estimated from the simulated images using the proposed method and compared with measurements obtained using the micro-CT images to evaluate the effect of voxel size on the accuracy of the method. Then, 19 of the 23 specimens were imaged using a clinical CT scanner. Cortical thickness and density were estimated from the clinical CT images using the proposed method and compared with the micro-CT measurements. Finally, a case-control study including 20 patients with osteoporosis and 20 age-matched controls with normal bone density was performed to evaluate the proposed method in a clinical context. RESULTS: Cortical thickness (density) estimation errors were 0.07 ± 0.19 mm (-18 ± 92 mg/cm(3)) using the simulated clinical CT volumes with the smallest voxel size (0.33 × 0.33 × 0.5 mm(3)), and 0.10 ± 0.24 mm (-10 ± 115 mg/cm(3)) using the volumes with the largest voxel size (1.0 × 1.0 × 3.0 mm(3)). A trend for the cortical thickness and density estimation errors to increase with voxel size was observed and was more pronounced for thin cortices. Using clinical CT data for 19 of the 23 samples, mean errors of 0.18 ± 0.24 mm for the cortical thickness and 15 ± 106 mg/cm(3) for the density were found. The case-control study showed that osteoporotic patients had a thinner cortex and a lower cortical density, with average differences of -0.8 mm and -58.6 mg/cm(3) at the proximal femur in comparison with age-matched controls (p-value < 0.001). CONCLUSIONS: This method might be a promising approach for the quantification of cortical bone thickness and density using clinical routine imaging techniques. Future work will concentrate on investigating how this approach can improve the estimation of mechanical strength of bony structures, the prevention of fracture, and the management of osteoporosis."