55 research outputs found

    RoSSO: A High-Performance Python Package for Robotic Surveillance Strategy Optimization Using JAX

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    To enable the computation of effective randomized patrol routes for single- or multi-robot teams, we present RoSSO, a Python package designed for solving Markov chain optimization problems. We exploit machine-learning techniques such as reverse-mode automatic differentiation and constraint parametrization to achieve superior efficiency compared to general-purpose nonlinear programming solvers. Additionally, we supplement a game-theoretic stochastic surveillance formulation in the literature with a novel greedy algorithm and multi-robot extension. We close with numerical results for a police district in downtown San Francisco that demonstrate RoSSO's capabilities on our new formulations and the prior work.Comment: 7 pages, 4 figures, 3 tables, submitted to the 2024 IEEE International Conference on Robotics and Automation. See https://github.com/conhugh/RoSSO for associated codebas

    A Stochastic Surveillance Stackelberg Game: Co-Optimizing Defense Placement and Patrol Strategy

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    Stochastic patrol routing is known to be advantageous in adversarial settings; however, the optimal choice of stochastic routing strategy is dependent on a model of the adversary. We adopt a worst-case omniscient adversary model from the literature and extend the formulation to accommodate heterogeneous defenses at the various nodes of the graph. Introducing this heterogeneity leads to interesting new patrol strategies. We identify efficient methods for computing these strategies in certain classes of graphs. We assess the effectiveness of these strategies via comparison to an upper bound on the value of the game. Finally, we leverage the heterogeneous defense formulation to develop novel defense placement algorithms that complement the patrol strategies.Comment: 9 pages, 1 figure, jointly submitted to the IEEE Control Systems Letters and the 2024 American Control Conference. Replaced in response to reviewer feedbac

    Numerical and Experimental Analyses of Hybrid Composites Made from Amazonian Natural Fibers

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    The application of lignocellulosic fibers as reinforcements in composite materials has found increasing use in recent years, due to the attractive characteristics of natural fibers such as their low cost, high specific modulus, biodegradability, abundance and with many technical qualities. Natural fiber hybrid composites are very frequently used in automotive aerospace and other industries. In this work, numerical and experimental analysis is carried out to compare curauá, jute and sisal fibers in epoxy composites for use in industry. The most appropriate hybridization effect by establishing the amounts of each fiber on the mechanical properties was considered. Finite Element Models were designed and validated through mechanical tests. The number of Finite Element models and specimens performed was determined through the design of experiments using the Taguchi Method and then the results were statistically validated. Higher strength was obtained in composites made with curauá fiber, followed by jute and sisal fibers. Such behavior was achieved by FEM and experimental tests, revealing an increase in tensile strength by increasing the amount of fibers up to 35% in total. Higher strength was achieved when the composite was made with curauá (20 wt.%), jute (10 wt.%) and sisal (5 wt.%) fibers. The results show a good agreement between the FEM and the experimental tests. Furthermore, the results of the present study were compared with those obtained previously mentioned in the open literature

    Abrolhos Bank Reef Health Evaluated by Means of Water Quality, Microbial Diversity, Benthic Cover, and Fish Biomass Data

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    The health of the coral reefs of the Abrolhos Bank (southwestern Atlantic) was characterized with a holistic approach using measurements of four ecosystem components: (i) inorganic and organic nutrient concentrations, [1] fish biomass, [1] macroalgal and coral cover and (iv) microbial community composition and abundance. The possible benefits of protection from fishing were particularly evaluated by comparing sites with varying levels of protection. Two reefs within the well-enforced no-take area of the National Marine Park of Abrolhos (Parcel dos Abrolhos and California) were compared with two unprotected coastal reefs (Sebastião Gomes and Pedra de Leste) and one legally protected but poorly enforced coastal reef (the “paper park” of Timbebas Reef). The fish biomass was lower and the fleshy macroalgal cover was higher in the unprotected reefs compared with the protected areas. The unprotected and protected reefs had similar seawater chemistry. Lower vibrio CFU counts were observed in the fully protected area of California Reef. Metagenome analysis showed that the unprotected reefs had a higher abundance of archaeal and viral sequences and more bacterial pathogens, while the protected reefs had a higher abundance of genes related to photosynthesis. Similar to other reef systems in the world, there was evidence that reductions in the biomass of herbivorous fishes and the consequent increase in macroalgal cover in the Abrolhos Bank may be affecting microbial diversity and abundance. Through the integration of different types of ecological data, the present study showed that protection from fishing may lead to greater reef health. The data presented herein suggest that protected coral reefs have higher microbial diversity, with the most degraded reef (Sebastião Gomes) showing a marked reduction in microbial species richness. It is concluded that ecological conditions in unprotected reefs may promote the growth and rapid evolution of opportunistic microbial pathogens

    Estimating the global conservation status of more than 15,000 Amazonian tree species

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    Estimates of extinction risk for Amazonian plant and animal species are rare and not often incorporated into land-use policy and conservation planning. We overlay spatial distribution models with historical and projected deforestation to show that at least 36% and up to 57% of all Amazonian tree species are likely to qualify as globally threatened under International Union for Conservation of Nature (IUCN) Red List criteria. If confirmed, these results would increase the number of threatened plant species on Earth by 22%. We show that the trends observed in Amazonia apply to trees throughout the tropics, and we predict thatmost of the world’s >40,000 tropical tree species now qualify as globally threatened. A gap analysis suggests that existing Amazonian protected areas and indigenous territories will protect viable populations of most threatened species if these areas suffer no further degradation, highlighting the key roles that protected areas, indigenous peoples, and improved governance can play in preventing large-scale extinctions in the tropics in this century

    Estimating the global conservation status of more than 15,000 Amazonian tree species

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    Una mirada prospectiva de la industria Risaraldense camino a la industria 4.0 : plan tecnológico 2020–2030 Centro de Diseño e Innovación Tecnológico Industrial

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    Se presenta el plan tecnológico del Centro de Diseño e Innovación Tecnológico Industrial del SENA para la vigencia 2002 - 2030. Comprende el análisis y diagnóstico de la industria risaraldense, sus necesidades y tendencias, con enfoque a la industria 4.0. Se provee información para: identificar tecnologías y ocupaciones emergentes que permitan anticipar la definición de perfiles de instructores, determinar requerimientos de modernización de infraestructura física y tecnológica del Centro de formación, actualizar, crear o eliminar programas de formación, establecer el tipo de formación, servicios tecnológicos e innovación que el centro de formación ofrecerá en un horizonte de 10 años e identificar los proyectos y actores estratégicos para el centro de formación.The technological plan of the SENA Industrial Technological Design and Innovation Center for the period 2002-2030 is presented. It includes the analysis and diagnosis of the Risaralda industry, its needs and trends, with a focus on industry 4.0. Information is provided to: identify emerging technologies and occupations that allow anticipating the definition of instructor profiles, determine modernization requirements of the physical and technological infrastructure of the Training Center, update, create or eliminate training programs, establish the type of training, services technology and innovation that the training center will offer over a 10-year horizon and identify projects and strategic actors for the training center.Fase I: análisis y diagnóstico estratégico -- Análisis externo del centro de formación -- Análisis interno del centro de formación -- Seguimiento al plan tecnológico inmediatamente anterior -- Cruce DOFA -- Vigilancia científico -tecnológica y competitiva especialidad energía eléctrica -- Vigilancia científico -tecnológica y competitiva especialidad electrónica y automatización -- Vigilancia científico -tecnológica y competitiva especialidad Mecánica Industrial -- Vigilancia científico -tecnológica y competitiva especialidad Informática, diseño y desarrollo de software -- Vigilancia científico -tecnológica y competitiva especialidad materiales para la industria -- Vigilancia científico -tecnológica y competitiva especialidad Automotor -- Vigilancia científico -tecnológica y competitiva especialidad Textil, confección y diseño -- Vigilancia científico -tecnológica y competitiva especialidad construcción e infraestructura -- Vigilancia científico -tecnológica y competitiva servicios tecnológicos -- Fase II: formulación estratégica -- Mapa de trayectoria tecnológica -- Validación con expertos -- Construcción de escenarios -- Formulación estratégica -- Métodos prospectivos utilizados -- Formulación estratégica -- Fase III: recomendaciones estratégicas -- Recomendaciones estratégicas especialidad energía eléctrica -- Recomendaciones estratégicas especialidad electrónica y automatización -- Recomendaciones estratégicas especialidad mecánica industrial -- Recomendaciones estratégicas especialidad Informática, diseño y desarrollo de software -- Recomendaciones estratégicas especialidad materiales para la industria -- Recomendaciones estratégicas especialidad Automotor -- Recomendaciones estratégicas especialidad Textil, confección y diseño -- Recomendaciones estratégicas especialidad construcción e infraestructura -- Recomendaciones estratégicas Sennova -- Servicios tecnológicos -- Introducción e información general -- Planteamiento de la necesidad u oportunidad -- Objetivos -- Desarrollo de la vigilancia científico-tecnológica -- Resultados de vigilancia tecnológica con base en análisis de patentes -- Identificación de tecnologías y sublíneas tecnológicas -- Comportamiento de los aceros -- Vigilancia normativa y regulatoria -- Vigilancia tecnológica -- Vigilancia competitiva -- Vigilancia comercial -- Resultados -- Conclusiones y recomendacionesna556 página

    Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

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    A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

    Mortality and pulmonary complications in patients undergoing surgery with perioperative SARS-CoV-2 infection: an international cohort study

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    Background: The impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on postoperative recovery needs to be understood to inform clinical decision making during and after the COVID-19 pandemic. This study reports 30-day mortality and pulmonary complication rates in patients with perioperative SARS-CoV-2 infection. Methods: This international, multicentre, cohort study at 235 hospitals in 24 countries included all patients undergoing surgery who had SARS-CoV-2 infection confirmed within 7 days before or 30 days after surgery. The primary outcome measure was 30-day postoperative mortality and was assessed in all enrolled patients. The main secondary outcome measure was pulmonary complications, defined as pneumonia, acute respiratory distress syndrome, or unexpected postoperative ventilation. Findings: This analysis includes 1128 patients who had surgery between Jan 1 and March 31, 2020, of whom 835 (74·0%) had emergency surgery and 280 (24·8%) had elective surgery. SARS-CoV-2 infection was confirmed preoperatively in 294 (26·1%) patients. 30-day mortality was 23·8% (268 of 1128). Pulmonary complications occurred in 577 (51·2%) of 1128 patients; 30-day mortality in these patients was 38·0% (219 of 577), accounting for 81·7% (219 of 268) of all deaths. In adjusted analyses, 30-day mortality was associated with male sex (odds ratio 1·75 [95% CI 1·28–2·40], p\textless0·0001), age 70 years or older versus younger than 70 years (2·30 [1·65–3·22], p\textless0·0001), American Society of Anesthesiologists grades 3–5 versus grades 1–2 (2·35 [1·57–3·53], p\textless0·0001), malignant versus benign or obstetric diagnosis (1·55 [1·01–2·39], p=0·046), emergency versus elective surgery (1·67 [1·06–2·63], p=0·026), and major versus minor surgery (1·52 [1·01–2·31], p=0·047). Interpretation: Postoperative pulmonary complications occur in half of patients with perioperative SARS-CoV-2 infection and are associated with high mortality. Thresholds for surgery during the COVID-19 pandemic should be higher than during normal practice, particularly in men aged 70 years and older. Consideration should be given for postponing non-urgent procedures and promoting non-operative treatment to delay or avoid the need for surgery. Funding: National Institute for Health Research (NIHR), Association of Coloproctology of Great Britain and Ireland, Bowel and Cancer Research, Bowel Disease Research Foundation, Association of Upper Gastrointestinal Surgeons, British Association of Surgical Oncology, British Gynaecological Cancer Society, European Society of Coloproctology, NIHR Academy, Sarcoma UK, Vascular Society for Great Britain and Ireland, and Yorkshire Cancer Research

    Evaluating the Effects of SARS-CoV-2 Spike Mutation D614G on Transmissibility and Pathogenicity.

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    Global dispersal and increasing frequency of the SARS-CoV-2 spike protein variant D614G are suggestive of a selective advantage but may also be due to a random founder effect. We investigate the hypothesis for positive selection of spike D614G in the United Kingdom using more than 25,000 whole genome SARS-CoV-2 sequences. Despite the availability of a large dataset, well represented by both spike 614 variants, not all approaches showed a conclusive signal of positive selection. Population genetic analysis indicates that 614G increases in frequency relative to 614D in a manner consistent with a selective advantage. We do not find any indication that patients infected with the spike 614G variant have higher COVID-19 mortality or clinical severity, but 614G is associated with higher viral load and younger age of patients. Significant differences in growth and size of 614G phylogenetic clusters indicate a need for continued study of this variant
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