836 research outputs found

    Relative effects of urbanisation, deforestation, and agricultural development on mosquito communities

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    Context: Despite numerous studies that showed negative effects of landscape anthropisation on species abundance and diversity, the relative effects of urbanisation, deforestation, and agricultural development as well as the spatial extent at which they act are much less studied. This is particularly the case for mosquitoes, which are the most important arthropods affecting human health. Objectives: We determined the scale of effect of these three landscape anthropisation components on mosquito abundance and diversity. We then assessed which landscape variables had the most effect as well as their independent positive or negative effects. Methods: We used mosquito data collected by Schaffner and Mathis (2013) in 16 sampling sites in Switzerland. We measured forest, urban and agricultural amounts in 485 concentric landscapes (from 150 to 5000 m radius) around each sampling site. We then identified the spatial extent at which each landscape metric best predicted abundance and diversity of mosquito species and compared the effect size of each landscape component on each response variable. Results: In Switzerland, urbanisation and deforestation have a greater influence on mosquito diversity than agricultural development, and do not act at the same scale. Conversely, the scale of effect on mosquito abundance is relatively similar across the different landscape anthropisation components or across mosquito species, except for Culex pipiens. However, the effect size of each landscape component varies according to mosquito species. Conclusion: The scale of management must be selected according to the conservation concern. In addition, a multi-scale approach is recommended for effective mosquito community management. Supplementary information: The online version contains supplementary material available at 10.1007/s10980-023-01634-w [Titel anhand dieser DOI in Citavi-Projekt übernehmen]

    Relevance of using a compressive preload in the cervical spine : an experimental and numerical simulating investigation

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    Simulating compressive action of muscles, a follower load attends to reproduce a more physiological biomechanical behaviour of the cervical spine. Only few experimental studies reported its influence on kinematics and intradiscal pressure in the cervical spine. STUDY DESIGN: In vitro human cadaveric and numerical simulating evaluation of a compressive preload in the cervical spine. OBJECTIVES: To analyse the influence of a compressive follower preload on the biomechanical behaviour of the cervical spine. METHODS: The present study was divided into two parts: part 1: in vitro investigation; part 2: numerical simulating analysis. Part 1: Twelve human cadaveric spines from C2 to T2 were evaluated intact and after application of a 50-N follower load. All tests were performed under load control by applying pure moments loading of 2 Nm in flexion/extension (FE), axial rotation (AR) and lateral bending (LB). Three-dimensional displacements were measured using an optoelectronic system, and intradiscal pressures were measured at two levels. Part 2: Using a 3D finite element model, we evaluated the influence of a 50- and 100-N compressive preload on intradiscal loads, facets forces and ranges of motion. Different positions of the follower load along the anteroposterior axis (±5 mm) were also simulated. RESULTS: Part 1: Mean variation of cervical lordosis was 5° ± 3°. The ROM slightly increased in FE, whereas it consistently decreased in AR and LB. Coupled lateral bending during AR was also reduced. Increase in hysteresis was observed on load-displacement curves only for AR and LB. Intradiscal pressures increased, but the aspect of load-pressure curves was altered in AR and LB. Part 2: Using the FE model, only minimal changes in ROM were noted following the simulation of a 50-N compressive load for the three loading conditions. Compared to intact condition, <10% variation was observed with regard to the different magnitude and positioning simulated. Intradiscal loads and facets forces were systematically increased by applying compressive preload. CONCLUSIONS: Although the follower load represents an attractive option to apply compressive preload during experimental tests, we found that this method could affect the native biomechanical behaviour of spine specimen depending on which movement was considered. Only minimal effects were observed in FE, whereas significant changes in kinematics and intradiscal pressures were observed for AR and LB

    Assessing Quality-Diversity Neuro-Evolution Algorithms Performance in Hard Exploration Problems

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    A fascinating aspect of nature lies in its ability to produce a collection of organisms that are all high-performing in their niche. Quality-Diversity (QD) methods are evolutionary algorithms inspired by this observation, that obtained great results in many applications, from wing design to robot adaptation. Recently, several works demonstrated that these methods could be applied to perform neuro-evolution to solve control problems in large search spaces. In such problems, diversity can be a target in itself. Diversity can also be a way to enhance exploration in tasks exhibiting deceptive reward signals. While the first aspect has been studied in depth in the QD community, the latter remains scarcer in the literature. Exploration is at the heart of several domains trying to solve control problems such as Reinforcement Learning and QD methods are promising candidates to overcome the challenges associated. Therefore, we believe that standardized benchmarks exhibiting control problems in high dimension with exploration difficulties are of interest to the QD community. In this paper, we highlight three candidate benchmarks and explain why they appear relevant for systematic evaluation of QD algorithms. We also provide open-source implementations in Jax allowing practitioners to run fast and numerous experiments on few compute resources.Comment: GECCO 2022 Workshop on Quality Diversity Algorithm Benchmark

    Distributed Access Control for Collaborative Applications using CRDTs

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    International audienceDistributed applications are part of our everyday lives, but too often their good operation depends on central servers, all potential points of failure and performance bottlenecks. Designing systems for fully distributed communications however still requires porting common mechanisms needed for feature-rich modern applications such as user rights differentiation, multiple administrators, and end-to-end encryption. We propose a distributed access control mechanism for collaborative applications by relying on conflict-free replicated data types (CRDT), and design an access control policy CRDT able to support Google Docs and POSIX file systems as example of distributed applications. To enforce that policy, we outline a generic data model, examine different conflict resolution strategies at the data and policy levels, and consider a novel approach towards conflicts between data and policy operations

    Are invasive marsh frogs ( Pelophylax ridibundus ) replacing the native P. lessonae

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    The water-frog L-E system, widespread in Western Europe, comprises the pool frog Pelophylax lessonae and the hybridogenetic edible frog P. esculentus, which originated from hybridization between pool frogs and marsh frogs (P. ridibundus). In P. esculentus, the lessonae (L) genome is eliminated during meiosis and has to be gained anew each generation from a P. lessonae partner, while the ridibundus (R′) genome is transmitted clonally. It therefore accumulates deleterious mutations, so that R′R′ offspring from P. esculentus×P. esculentus crosses are normally unviable. This system is now threatened by invasive P. ridibundus (RR) imported from Eastern Europe and the Balkans. We investigated the genetic interactions between invasive marsh frogs and native water frogs in a Swiss wetland area, and used genetic data collected in the field to validate several components of a recently postulated mechanism of species replacement. We identified neo-ridibundus individuals derived from crosses between invasive ridibundus and native esculentus, as well as newly arisen hybridogenetic esculentus lineages stemming from crosses between invasive ridibundus (RR) and native lessonae (LL). As their ridibundus genomes are likely to carry less deleterious mutations, such lineages are expected to produce viable ridibundus offspring, contributing to species replacement. However, such crosses with invasive ridibundus only occurred at a limited scale; moreover, RR×LL crosses did not induce any introgression from the ridibundus to the lessonae genome. We did not find any ridibundus stemming from crosses between ancient esculentus lineages. Despite several decades of presence on the site, introduced ridibundus individuals only represent 15% of sampled frogs, and their spatial distribution seems shaped by specific ecological requirements rather than history of colonization. We therefore expect the three taxa to coexist stably in this area

    Continuing Distance Education: A Capacity-Building Tool for the De-isolation of Care Professionals and Researchers

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    Background: There are large disparities in access to health-care professionals (HCP) in low-income African countries, leading to imbalanced and suboptimal health delivery. Part of the difficulty is recruiting and retaining care professionals to work in isolated settings. Aim: To evaluate the impact of distance continuing education as a way to build capacity, increase satisfaction and enhance the performance of care professionals in these isolated health-care facilities. Setting: Care professionals using RAFT (Telemedicine Network in French-speaking Africa) in isolated care facilities. Program Description: Within RAFT, an organizational framework and computer-based tools have been developed and evolved to provide useful, qualitative, applicable training material. Program Evaluation: The activity, satisfaction, perceptions and impact of RAFT on remote health-care workers are being monitored. RAFT's potential to improve the recruitment, satisfaction and retention of care professionals in remote settings is widely recognized; however, the actual impact on the performance and quality of care remains to be demonstrate

    Complexity assessment and technical aspect of coronary angiogram and percutaneous coronary intervention following transcatheter aortic valve implantation

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    Background: Performing selective coronary angiogram (CA) and percutaneous coronary intervention (PCI) post transcatheter aortic valve implantation (TAVI) may be challenging with various success rates of coronary ostia engagement. Methods: Among all patients who underwent CA and/or PCI after TAVI from our single center TAVI registry, ostia cannulation success was reported according to the quality of ostia engagement and artery opacification, and was classified as either selective, partially selective or non-selective but sufficient for diagnosis. Results: Among the 424 consecutive TAVI procedures performed at the aforementioned institution, 20 (4.7%) CA were performed in 19 (4.5%) patients at a median time of 464 days post TAVI (25–75% IQ: 213–634 days). CA were performed in 7 CoreValve, 9 Evolut R, 1 Evolut PRO and 2 Edwards Sapien 3 devices. Transradial vascular approach was attempted in 9 procedures (45%, right n = 6 and left n = 3) and was successful in 8 (40%) patients. A total of 20 left main artery ostium cannulation were attempted leading to a diagnostic CA in all of them with selective engagement in 65%.  Engagement of the right coronary artery in 2 out of 15 attempted cases failed due to a low ostium in conjunction with a high implantation of a CoreValve prosthesis. 11 PCI (55% of CA) including 2 left main lesions were performed. In 4 patients (36.4% of the PCI), an extension catheter was required to engage the left main. All planned PCI were successful. Conclusions: Post TAVI CA and PCI are challenging but feasible even after supra-annular self-expandable valve implantation

    Procédés de fabrication en matériaux composites de pièces tridimensionnelles et/ou massives

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    L'invention concerne un procédé pour fabriquer en matériau composite une pièce brute ayant une forme massive et/ou tridimensionnelle, comprenant les étapes de : - bobiner à chaud au moins un toron de fibres renforçantes (24) imprégné de résine thermoplastique en quantité excédentaire, sur des reliefs de bobinage (17-23 ) d'un outillage de bobinage (16), pour constituer une préforme de la pièce fabriquée ; - matricer à chaud la préforme pour lui donner une forme souhaitée tout en évacuant la résine excédentaire ; - refroidir l'ensemble en maintenant sous pression l'outillage de matriçage (31) pour constituer la pièce brute. L'invention s'applique à la fabrication de pièces mécaniques structurelles telles que des pièces structurelles aéronautiques
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