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Authoritarian incumbents routinely use democratic emulation as a strategy to extend their tenure in power. Yet, there is also evidence that multiparty competition makes electoral authoritarianism more vulnerable to failure. Proceeding from the assumption that the outcomes of authoritarian electoral openings are inherently uncertain, it is argued in this article that the institutionalisation of elections determines whether electoral authoritarianism promotes stability or vulnerability. By ‘institutionalisation’, it is meant the ability of authoritarian regimes to reduce uncertainty over outcomes as they regularly hold multiparty elections. Using discrete‐time event‐history models for competing risks, the effects of sequences of multiparty elections on patterns of regime survival and failure in 262 authoritarian regimes from 1946 to 2010 are assessed, conditioned on their degree of competitiveness. The findings suggest that the institutionalisation of electoral uncertainty enhances authoritarian regime survival. However, for competitive electoral authoritarian regimes this entails substantial risk. The first three elections substantially increase the probability of democratisation, with the danger subsequently diminishing. This suggests that convoking multiparty competition is a risky game with potentially high rewards for autocrats who manage to institutionalise elections. Yet, only a small number of authoritarian regimes survive as competitive beyond the first few elections, suggesting that truly competitive authoritarianism is hard to institutionalise. The study thus finds that the question of whether elections are dangerous or stabilising for authoritarianism is dependent on differences between the ability of competitive and hegemonic forms of electoral authoritarianism to reduce electoral uncertainty.

O trabalho presente trata de teoria dos modelos em feixes de L-estruturas sobre uma álgebra de Heyting completa 'omega'. Modificando a noção dos símbolos de constantes de uma linguagem de primeira ordem, admitindo uma existência parcial, generalizamos o método dos diagramas e diagramas elementares devido a A. Robinson para L-estruturas na categoria 'pSh(omega)'. Além disso, melhoramos o teorema de Fraïssé aparecendo em [6] para L-estruturas na categoria 1Sh(omega)'. Demonstramos o teorema da completude em todos os detalhes para feixes de L-estruturas, mostramos que para toda teoria intuicionista consistente podemos construir - usando a álgebra de Lindenbaum - um feixe de L-estruturas sobre uma álgebra de Heyting completa. Também demonstramos para a linguagem L# - uma linguagem usual de primeira ordem sem o quantificador universal - o teorema de existência de modelos para feixes sobre espaços topológicos. Para isso, introduzimos o espaço espectral das extensões primas. Finalmente, generalizamos o teorema de omissão de tipos para lógica intuicionista, usando o teorema de existência de modelos e o teorema de Baire The present work is dealing with model theory in sheaves of L-structures over a complete Heyting algebra 'omega'. Modifying the notion of the symbols of constantes in a first order language, allowing a parcial existence, we will generalize the method of diagrams and elementary diagrams originated by A. Robinson in the context o L-structures in the category 'pSh(omega)'. Further-more, we will improve Fraïssé's theorem, apearing in [6], for L-structures in the category 'Sh(OMEGA)'. In all details we will demonstrate the completeness theorem for sheaves of L-structures, for a intutionistic, consistent theory we will prove - using the Lindenbaum algebra - that we can construct a sheaf of L-structures over a complete Heyting algebra. We will demonstrate for a language L# - a usual first order language without the universal quantifier - the model existence theorem for sheaves over topological spaces. For this, we will introduce the spectral space of prime extensions. Using this model existence theorem and Baire's theorem, we will genweralize the ommiting types theorem for the intuitionistic logic

Additional file 3: Table S1. Resuscitation room admission criteria for nontraumatic critically ill patients based on the ABCDE approach in the external validation cohort (OBSERvE study)���.

This paper summarizes the challenges of deep space planetary robotic-exploration missions, using the example of the DLR Autonomous Navigation Experiment within the MMX Rover project, and presents a preliminary design of the proposed solution to safe navigation of the MMX Rover on Pho-bose The MMX Rover, a joint contribution of the German Aerospace Center (DLR) and the Centre National dEtudes Spatiales (CNES) is part of the Martian Moons eXploration (MMX) Mission by the Japan Aerospace Exploration Agency (JAXA), whose mission objective is to understand the origin of the two Martian moons. The mission involves scientific data collection and a sample return from Phobos, the bigger of the two Martian moons. The mission is scheduled to launch in the third quarter of 2024. The MMX Rover will fly as a payload and will be jettisoned onto Phobos from a low altitude of about 40 metres. The rover has multiple objectives: terrain assessment to mitigate the risk for the sample-return approach of the spacecraft, exploration of the surface of Phobos and act as a scientific and technology demonstration platform. In this context, the Robotics and Mechatronics Institute, DLR, is preparing to perform an Autonomous Navigation Experiment as a technology demonstration to showcase the advantages of robot autonomy for exploring distant celestial bodies. If successful, the MMX Rover will be the first man-made object to land on and explore Phobos.

The MMX - Martian Moons eXploration - mission, as the name already suggests, aims to explore the two moons of Mars, Phobos and Deimos. The goal of this space mission led by JAXA is to acquire the scientific data necessary to understand the composition, structure, and history of these peculiar celestial bodies. The first man-made object to ever land on the larger and closer of these two moons, Phobos, shall be the small and lightweight MMX rover. The rover will be designed, manufactured and operated jointly by CNES and DLR. After separation from the carrier spacecraft, landing, uprighting, and deployment, this rover will start to drive in the low-gravity environment of Phobos surface and perform scientific operations. The rover will have a length of 44cm and a weight below 30kg. It will be solar-powered to operate for an intended mission duration of 90 days [1]. Communication round-trip times between Earth and Mars are already eight to forty minutes. For Phobos, we expect significantly higher values due to the need for relay satellites and limited communication windows. This leads to a requirement for a high level of autonomy for the robot, particularly its navigation capabilities, in order to maximize the scientific output of the mission. We will thus develop a navigation solution and integrate it as a software component running on the MMX rovers on-board computer. This navigation software will be verified in the introductory commissioning phase and is intended to be useful in the subsequent main operations phase. On the one hand, our design is inspired by the previous successful NASA planetary rovers, which have been the pioneers of this software technology. On the other hand, the design of the MMX rover brings its own sets of specifics and limitations to the table, and the uncharted celestial body Phobos itself is a source of several major and unprecedented challenges. For some of these, we can build upon the experience gained with the MASCOT mobile asteroid lander [2], which was deployed on the asteroid Ryugu in 2018 and successfully performed jumps for relocalization in the micro-gravity environment. The most notable challenges provided by the MMX rover design are the navigation cameras located at a fixed position and orientation w.r.t. the rovers body at a height of only 30cm above ground; the skid-steered locomotion of the rover limiting its turning speed; and restrictions on weight and power consumption further limiting the range of permissible operations. The most notable challenges provided by Phobos include not knowing the map of the terrain at the operational scale beforehand - the best maps available are at a resolution of 5m/px; the unknown soil composition; and the unknown local gravity. The combination of the rover and the celestial body is also a source of challenges: the behavior of wheels in contact with the soil is impossible to investigate beforehand, apart from software simulations, and Phobos very fast rotation - a Phobos day only lasts eight Earth hours - in the combination with the very slow maximum rover speed of approximately 4mm/s, makes shadows move relatively quickly, which could confuse visual odometry approaches. The on-board computer provides its own set of limitations and pre-requisites such as memory allocation and orchestration of concurrently running software processes. In our workshop contribution, we will identify and categorize challenges for navigation on Phobos and sketch our planned solutions to tackle them. Our planned navigation architecture will contain several FPGA and CPU-based modules: Dense depth data will be computed via Semi-Global Matching [3] on a FPGA. This is the basis for a stereo visual odometry such as [4] used to estimate the robot's trajectory. Further modules include an obstacle classification on individual depth images similar to [5] and possibly further mapping modules to create maps in compact representations to be sent to operators on Earth. Such obstacle and map information can then be used to realize autonomous emergency stop behavior up to future reactive obstacle avoidance or path planning modules to support (semi-)autonomous operation. These developments are based on experience we gained developing complex autonomous robotic navigation systems [6, 7] that we tested and evaluated in several field tests at Moon-analogue environments on the volcano Mt. Etna, Sicily, Italy [8, 9]. Some of the greatest challenges arise from the daring ambition to bring a rover into an environment where mankind has never been before, and expecting it to drive there to some extent autonomously. But that is also what makes this mission interesting in the first place. The scientific and technological discussions at the workshop may both help us to steer our decision making and enrich the scientific community with our findings. References: [1] J. Bertrand, et al., Roving on Phobos: Challenges of the MMX Rover for Space Robotics, ASTRA (2019) [2] J. Reill et al., MASCOT - Asteroid Lander with Innovative Mobility Mechanism, ASTRA (2015) [3] H. Hirschmüller, Stereo processing by semiglobal matching and mutual information, TPAMI (2007) [4] H. Hirschmüller, et al., Fast, unconstrained camera motion estimation from stereo without tracking and robust statistics, ICARCV (2002) [5] C. Brand, et al., Stereo-Vision Based Obstacle Mapping for Indoor / Outdoor SLAM, IROS (2014) [6] M. J. Schuster, et al., Towards Autonomous Planetary Exploration: The Lightweight Rover Unit (LRU), its Success in the SpaceBotCamp Challenge, and Beyond, JINT (2017) [7] M. J. Schuster, et al., Distributed stereo vision-based 6D localization and mapping for multi-robot teams, JFR (2018) [8] M. Vayugundla, et al., Datasets of Long Range Navigation Experiments in a Moon Analogue Environment on Mount Etna, ISR (2018) [9] A. Wedler, et al., First Results of the ROBEX Analogue Mission Campaign: Robotic Deployment of Seismic Networks for Future Lunar Missions, IAC (2017)

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