69 research outputs found
E-democracy: exploring the current stage of e-government
Governments around the world have been pressured to implement e-Government programs in order to improve the government-citizen dialogue. The authors of this article review prior literature on such efforts to find if they lead to increased democratic participation ("e-Democracy") for the affected citizens, with a focus on the key concepts of transparency, openness, and engagement. The authors find that such efforts are a starting point toward e-Democracy, but the journey is far from complete
COMPARISON STUDY OF THE ACCURACY OF SLAM TECHNIQUES AND SENSOR SELECTION FOR LUNAR EXPLORATION
Robotics navigation on the lunar surface is crucial for future lunar prospection missions. Visual Simultaneous Localisation And Mapping (vSLAM) bears several advantages over traditional Simultaneous Localisation And Mapping (SLAM) methods, such as mitigating wheel slip and using sensors with space heritage. Still, extreme environments create challenges for optical sensors. This work proposes a qualitative analysis of which elements influence the performance of vSLAM for lunar environments through an experimental approach in an analogue lunar facility
OmniLRS: A Photorealistic Simulator for Lunar Robotics
Developing algorithms for extra-terrestrial robotic exploration has always
been challenging. Along with the complexity associated with these environments,
one of the main issues remains the evaluation of said algorithms. With the
regained interest in lunar exploration, there is also a demand for quality
simulators that will enable the development of lunar robots. % In this paper,
we explain how we built a Lunar simulator based on Isaac Sim, Nvidia's robotic
simulator. In this paper, we propose Omniverse Lunar Robotic-Sim (OmniLRS) that
is a photorealistic Lunar simulator based on Nvidia's robotic simulator. This
simulation provides fast procedural environment generation, multi-robot
capabilities, along with synthetic data pipeline for machine-learning
applications. It comes with ROS1 and ROS2 bindings to control not only the
robots, but also the environments. This work also performs sim-to-real rock
instance segmentation to show the effectiveness of our simulator for
image-based perception. Trained on our synthetic data, a yolov8 model achieves
performance close to a model trained on real-world data, with 5% performance
gap. When finetuned with real data, the model achieves 14% higher average
precision than the model trained on real-world data, demonstrating our
simulator's photorealism.% to realize sim-to-real. The code is fully
open-source, accessible here: https://github.com/AntoineRichard/LunarSim, and
comes with demonstrations.Comment: 7 pages, 4 figure
REALMS 2 -RESILIENT EXPLORATION AND LUNAR MAPPING SYSTEM 2
The European Space Agency (ESA) and the European Space Resources Innovation Centre (ESRIC) created the Space Resources Challenge to invite researchers to propose innovative solutions for robotic space prospection with focus on autonomous Multi-Robot System (MRS). This paper proposes Resilient Exploration And Lunar Mapping System 2 (REALMS2), a MRS framework for planetary prospection and mapping. It is based on Robot Operating System version 2 (ROS 2) and uses Visual Simultaneous Localisation And Mapping (vSLAM) for map generation. The REALMS2 uses a mesh network for a robust ad-hoc network. A single graphical user interface (GUI)) controls all the rovers, providing a simple overview of the robotic mission. REALMS2 was used during the second field test of the ESA-ESRIC Challenge and allowed to map around 60% of the area, using three homogeneous rovers while handling communication delays and blackouts
Paths to wider adoption of e-infrastructure services
This paper presents work conducted as part of the e-Uptake project, which aims to widen the uptake of e-Infrastructure services for research. We will discuss our fieldwork conducted so far, give examples of the barriers and enablers identified and discuss how using the accumulated knowledge can lead to paving the way for wider adoption of e Infrastructure Services
The Yield of Routine Post-Operative Doppler Ultrasound to Detect Early Post-Liver Transplantation Vascular Complications
Early detection of liver transplantation (LT) vascular complications enables timely management. Our aim was to assess if routine Doppler ultrasound (rDUS) improves the detection of hepatic artery thrombosis (HAT), portal vein thrombosis (PVT) and hepatic venous outflow obstruction (HVOO). We retrospectively analysed timing and outcomes, number needed to diagnose one complication (NND) and positive predictive value (PPV) of rDUS on post-operative day (POD) 0,1 and 7 in 708 adult patients who underwent primary LT between 2010–2022. We showed that HAT developed in 7.1%, PVT in 8.2% and HVOO in 3.1% of patients. Most early complications were diagnosed on POD 0 (26.9%), 1 (17.3%) and 5 (17.3%). rDUS correctly detected 21 out of 26 vascular events during the protocol days. PPV of rDUS was 53.8%, detection rate 1.1% and NND was 90.5. Median time to diagnosis was 4 days for HAT and 47 days for PVT and 21 days for HVOO. After intervention, liver grafts were preserved in 57.1%. In conclusion, rDUS protocol helps to detect first week’s vascular events, but with low PPV and a high number of ultrasounds needed.</p
The Yield of Routine Post-Operative Doppler Ultrasound to Detect Early Post-Liver Transplantation Vascular Complications
Early detection of liver transplantation (LT) vascular complications enables timely management. Our aim was to assess if routine Doppler ultrasound (rDUS) improves the detection of hepatic artery thrombosis (HAT), portal vein thrombosis (PVT) and hepatic venous outflow obstruction (HVOO). We retrospectively analysed timing and outcomes, number needed to diagnose one complication (NND) and positive predictive value (PPV) of rDUS on post-operative day (POD) 0,1 and 7 in 708 adult patients who underwent primary LT between 2010–2022. We showed that HAT developed in 7.1%, PVT in 8.2% and HVOO in 3.1% of patients. Most early complications were diagnosed on POD 0 (26.9%), 1 (17.3%) and 5 (17.3%). rDUS correctly detected 21 out of 26 vascular events during the protocol days. PPV of rDUS was 53.8%, detection rate 1.1% and NND was 90.5. Median time to diagnosis was 4 days for HAT and 47 days for PVT and 21 days for HVOO. After intervention, liver grafts were preserved in 57.1%. In conclusion, rDUS protocol helps to detect first week’s vascular events, but with low PPV and a high number of ultrasounds needed.</p
Cross-Reactivity of Virus-Specific CD8+ T Cells Against Allogeneic HLA-C: Possible Implications for Pregnancy Outcome
Heterologous immunity of virus-specific T cells poses a potential barrier to transplantation tolerance. Cross-reactivity to HLA-A and -B molecules has broadly been described, whereas responses to allo-HLA-C have remained ill defined. In contrast to the transplant setting, HLA-C is the only polymorphic HLA molecule expressed by extravillous trophoblasts at the maternal-fetal interface during pregnancy. Uncontrolled placental viral infections, accompanied by a pro-inflammatory milieu, can alter the activation status and stability of effector T cells. Potential cross-reactivity of maternal decidual virus-specific T cells to fetal allo-HLA-C may thereby have detrimental consequences for the success of pregnancy. To explore the presence of cross-reactivity to HLA-C and the other non-classical HLA antigens expressed by trophoblasts, HLA-A and -B-restricted CD8+ T cells specific for Epstein-Barr virus, Cytomegalovirus, Varicella-Zoster virus, and Influenza virus were tested against target cells expressing HLA-C, -E, and -G molecules. An HLA-B*08:01-restricted EBV-specific T cell clone displayed cross-reactivity against HLA-C*01:02. Furthermore, cross-reactivity of HLA-C-restricted virus-specific CD8+ T cells was observed for HCMV HLA-C*06:02/TRA CD8+ T cell lines and clones against HLA-C*03:02. Collectively, these results demonstrate that cross-reactivity against HLA-C can occur and thereby may affect pregnancy outcome
REALMS: Resilient exploration and lunar mapping system.
peer reviewedSpace resource utilisation is opening a new space era. The scientific proof of the presence of water ice on the south pole of the Moon, the recent advances in oxygen extraction from lunar regolith, and its use as a material to build shelters are positioning the Moon, again, at the centre of important space programs. These worldwide programs, led by ARTEMIS, expect robotics to be the disrupting technology enabling humankind's next giant leap. However, Moon robots require a high level of autonomy to perform lunar exploration tasks more efficiently without being constantly controlled from Earth. Furthermore, having more than one robotic system will increase the resilience and robustness of the global system, improving its success rate, as well as providing additional redundancy. This paper introduces the Resilient Exploration and Lunar Mapping System, developed with a scalable architecture for semi-autonomous lunar mapping. It leverages Visual Simultaneous Localization and Mapping techniques on multiple rovers to map large lunar environments. Several resilience mechanisms are implemented, such as two-agent redundancy, delay invariant communications, a multi-master architecture different control modes. This study presents the experimental results of REALMS with two robots and its potential to be scaled to a larger number of robots, increasing the map coverage and system redundancy. The system's performance is verified and validated in a lunar analogue facility, and a larger lunar environment during the European Space Agency (ESA)-European Space Resources Innovation Centre Space Resources Challenge. The results of the different experiments show the efficiency of REALMS and the benefits of using semi-autonomous systems
Eigenvalue asymptotics for weighted Laplace equations on rough Riemannian manifolds with boundary
Our topological setting is a smooth compact manifold of dimension two or
higher with smooth boundary. Although this underlying topological structure is
smooth, the Riemannian metric tensor is only assumed to be bounded and
measurable. This is known as a rough Riemannian manifold. For a large class of
boundary conditions we demonstrate a Weyl law for the asymptotics of the
eigenvalues of the Laplacian associated to a rough metric. Moreover, we obtain
eigenvalue asymptotics for weighted Laplace equations associated to a rough
metric. Of particular novelty is that the weight function is not assumed to be
of fixed sign, and thus the eigenvalues may be both positive and negative. Key
ingredients in the proofs were demonstrated by Birman and Solomjak nearly fifty
years ago in their seminal work on eigenvalue asymptotics. In addition to
determining the eigenvalue asymptotics in the rough Riemannian manifold setting
for weighted Laplace equations, we also wish to promote their achievements
which may have further applications to modern problems
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