NETRA: Interactive Display for Estimating Refractive Errors and Focal Range

We introduce an interactive, portable, and inexpensive solution for estimating refractive errors in the human eye. While expensive optical devices for automatic estimation of refractive correction exist, our goal is to greatly simplify the mechanism by putting the human subject in the loop. Our solution is based on a high-resolution programmable display and combines inexpensive optical elements, interactive GUI, and computational reconstruction. The key idea is to interface a lenticular view-dependent display with the human eye in close range - a few millimeters apart. Via this platform, we create a new range of interactivity that is extremely sensitive to parameters of the human eye, like refractive errors, focal range, focusing speed, lens opacity, etc. We propose several simple optical setups, verify their accuracy, precision, and validate them in a user study.Alfred P. Sloan Foundation (Research Fellowship

On the Discovery of Monocular Rivalry by Tscherning in 1898:Translation and Review

Monocular rivalry was named by Breese in 1899. He made prolonged observation of superimposed orthogonal gratings; they fluctuated in clarity with either one or the other grating occasionally being visible alone. A year earlier, Tscherning observed similar fluctuations with a grid of vertical and horizontal lines and with other stimuli; we draw attention to his prior account. Monocular rivalry has since been shown to occur with a wide variety of superimposed patterns with several independent rediscoveries of it. We also argue that Helmholtz described some phenomenon other than monocular rivalry in 1867

Subsidence monitoring using SAR interferometry: Reduction of the atmospheric effects using stochastic filtering

The atmospheric effects represent one of the major limits of SAR interferometry as a quantitative technique to monitor subsidences. In this work, which focuses on subsidences of small spatial extent, a procedure to reduce these effects is described. The atmospheric component of the interferometric phase is estimated adopting a filtering and prediction procedure, which exploits the phase over stable areas identified in the vicinity of the analysed subsidence area. The procedure was validated on a suitable test site located in North-eastern Spain. Furthermore, it was employed in the study of a small-scale subsidence, where the interferometric results were validated using precise geodetic observations

High-resolution regional gravity field recovery from Poisson wavelets using heterogeneous observational techniques

2016-2017 > Academic research: refereed > Publication in refereed journal201804_a bcmaVersion of RecordPublishe

Non-stationary covariance function modelling in 2D least-squares collocation

Standard least-squares collocation (LSC) assumes 2D stationarity and 3D isotropy, and relies on a covariance function to account for spatial dependence in the ob-served data. However, the assumption that the spatial dependence is constant through-out the region of interest may sometimes be violated. Assuming a stationary covariance structure can result in over-smoothing of, e.g., the gravity field in mountains and under-smoothing in great plains. We introduce the kernel convolution method from spatial statistics for non-stationary covariance structures, and demonstrate its advantage fordealing with non-stationarity in geodetic data. We then compared stationary and non-stationary covariance functions in 2D LSC to the empirical example of gravity anomaly interpolation near the Darling Fault, Western Australia, where the field is anisotropic and non-stationary. The results with non-stationary covariance functions are better than standard LSC in terms of formal errors and cross-validation against data not used in the interpolation, demonstrating that the use of non-stationary covariance functions can improve upon standard (stationary) LSC

Lessons learnt on Requirement Analyses to establish new model systems: Prerequisites to assure model use towards policy outcome

The objective of the paper is to evaluate the applied non-standardised Model Requirement Analysis (MRA). Using the presented methods and results of the MRA, we discuss the suitability for appropriate ways to improve applied methods using the example of the Sustainability Impact Assessment Tools (SIAT). Special focus is given to the prerequisites of project design to assure model use towards model outcome. The applied methods of the MRA consist of evolutionary prototyping, which provides a way to structure the subsequent group discussions with end-users. The results first summarise the conducted interactions with potential end-users and evaluate the usefulness of conducting MRA for each end-user meeting. A direct outcome of the MRA is the identification of four categories of requirements for the SIAT design: (a) Spatial, time and thematic integration, (b) technical performance and system advancements, (c) quality assurance of data and model systems results and (d) organisational linkages for model system embedding. We give a number of reasons why the undertaken development process of SIAT was not sufficient for actual operational use towards outcome at the level of policy decision making. A number of recommendations and rules for stakeholder involvement and development methods are suggested in the conclusions

Ex Ante Impact Assessment of Policies Affecting Land Use, Part A: Analytical Framework

Contemporary policy making calls for scientific support to anticipate the possible consequences of optional policy decisions on sustainable development. This paper presents an analytical framework for ex ante assessment of economic, social, and environmental impacts of policy driven land use changes that can be used as an aid to policy making. The tasks were to (1) link policy scenarios with land use change simulations, (2) link land use change simulations with environmental, social, and economic impacts through indicators, and (3) valuate the impacts in the context of sustainable development. The outcome was a basis for dialogue at the science-policy interface in the process of developing new policies on the European level that impact on land and land use. The analytical approach provides a logical thread for ex ante impact assessment within the context of sustainable development, land use multifunctionality, and land use change and it provides a thorough discussion of achievements and open challenges related to the framework. It concludes with considerations on the potential for using evidence based ex ante assessments in the process of policy development. The paper is complemented by a B-paper providing exemplary results from two applications of the framework: a financial reform scenario of the Common Agricultural Policy of the European Union, and a bioenergy policy scenario for the case of Poland (Helming et al. 2011)

Sustainability Impact Assessment Tools (SIAT) for Regionalised European Impact Analysis: Focusing on the design process

The SENSOR project aims at delivering ex-ante Sustainability Impact Assessment Tools (SIAT) to support decision making on policies related to multifunctional land use in European regions. Decision support tools are required that provide scientifically substantiated anticipations of the effects of future policy options on sustainability issues. SENSOR responds to these information needs at European land use policy level with the SIAT, which is interactively designed with end users (Helming et al. 2008). This paper illustrates the design process of the SIAT under the concurrent condition of a high usability for end users. To meet this goal, end user involvements by using techniques of software prototyping is applied. Impact Assessment (IA) is an important instrument towards the fulfilment of the European Sustainable Development Strategy (EC 2001). This obligatory process has to be undertaken before decisions on policy proposals at European level are made (EC 2005). The European Commission provided in the European IA Guidelines detailed methodological steps on the procedure of IA (EC 2005). SIAT covers the two methodological steps of (a) analysing policy options against the divergence to defined objectives and (b) comparing policy options among each other. IA procedures are prevalently supported by operational tools that are often restricted to precise, quantitative sector information. They focus mostly on single aspects of economic, social or environmental impacts and are mainly designed for ex-post analysis (Bartolomeo et al. 2004). Integrated and comprehensive questions are less answered (Tamborra 2002). SIAT intends to bridge this gap and thus focuses on impact assessment towards an integrated perspective. Region-explicit policy impacts are analysed across six sectors on economic, environmental and social indicators (Sieber et al. 2008, Verweij et al. 2006). The major challenge is the transformation of interdisciplinary knowledge into an adequate model-design that meets the end user requirements. At the same time high standards of technical performance and evident functionality should be ensured: In particular, (a) short response time, (b) maximum flexibility regarding re-useability of applying scenarios, (c) fast integration of new intended policies for impact analysis, (d) high compatibility of different calculation methods, (e) effectual reliability and plausibility of simulation results.The research question asks for a method to assure both, meeting the end user requirements as well as the above described standards. To meet these goals the method of software prototyping related to end user involvements is described in detail. Thus, the paper illustrates in chapter 2.1 the SIAT design and methodology, in chapter 2.2 the applied process of operational prototyping. Chapter 3 concludes in terms of so far achieved results

Field Evaluation of Calypte’s AWARE™ Blood Serum Plasma (BSP) and Oral Mucosal Transudate (OMT) Rapid Tests for Detecting Antibodies to HIV-1 and 2 in Plasma and Oral Fluid

As programs to prevent and care for HIV-infected persons are scaled-up in Africa, there is the need for continuous evaluation of the performance of test kits that could best support these programs. The present study evaluated the sensitivity, specificity, ease of use, and cost of AWARE ™ Blood Serum Plasma (BSP) and Oral Mucosal Transudate (OMT) Rapid HIV-1/2 test kits using real-time and archived samples of HIV-infected persons from Cameroon. Matched whole blood and OMT specimens were collected prospectively from HIV-positive and HIV-negative persons from different regions of Cameroon and tested using the AWARE ™ BSP and OMT test kits, respectively. These results were compared to the gold standard that included a combination of Determine HIV-1/2 and Enzygnost HIV-1/2. The BSP Rapid test kit was further evaluated using well characterized panels of HIV-2 and HIV-1 group O samples. Cost and end-user analysis of the OMT test kit was done by comparing its actual cost, consumables, safety, bench time and manipulation with other test kits. Of the 732 matched samples, 412 (56.3%) and 320 (43.7%) were from females and males, respectively. Of these samples, 23 (3.1%) gave discordant results between Determine HIV-1/2 and Enzygnost HIV1/2 and were excluded from the analysis. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the AWARE™ BSP were 100%. The AWARE™ OMT had 98.8% sensitivity, 98.9% specificity, 98.0% PPV and 99.4% NPV. The results of a well-characterized archived panel of HIV-2 (n=7) and HIV-1 group O (n=3) samples using the AWARE™ BSP Rapid test kit gave 100% concordance. Total per patient cost of the AWARE OMT rapid test kit was US$4.72 compared to a mean cost of US$7.33 ± 0.11 for the other test kits. Both the AWARE™ BSP and OMT Rapid test kits demonstrated high sensitivities and specificities on all samples tested and were well adapted for use in resource-constrained settings with high HIV heterogeneity such as Cameroon. The AWARE ™ HIV-1/2 OMT Rapid test kit appears to be the cheapest, safest and easiest to use compared with other available test kits