Université de Rennes 1
Recent publications
Suction sampling is increasingly being used to estimate abundance and diversity of epigeal arthropods, yet no study has quantified its efficiency to simultaneously assess diversity at different taxonomic and functional scales. Here, we evaluated the efficiency of this method (G-Vac) relative to the pitfall (Barber) trap, which has been used for a long time, and their possible complementarity. To do that, we compared several diversity metrics of a wide range of arthropod taxa, with a particular focus on spiders (species level), and using functional traits such as trophic diet, hunting guild, and body size. Sampling took place in some coastal grasslands of Brittany (France) using a spatially paired design of vacuuming and unfenced pitfall trapping. In total, 21159 arthropods were identified to order or family levels, including 1018 adult spiders identified to species. Suction sampling was more efficient than pitfall trapping in collecting phytophagous arthropods, web-builders, and small species living in the vegetation compared to detritivores, large-bodied arthropods, and spiders living near the soil surface. We conclude that short-term G-Vac suction is more interesting than pitfall trapping to obtain a ‘snapshot’ of patterns in taxonomic richness. However, for assessing functional diversity, G-Vac suction and pitfall trapping are complementary sampling methods
Considering the plant microbiota, temporal changes are expected depending on plant development stages and environmental pressures because of modifications in plant requirements and available soil microbial reservoir. Herein, we analyzed the composition of root endosphere microbiota of grafted vine plants using two grapevine cultivars (Merlot and Cabernet-Sauvignon as scion grafted on rootstocks of different clones) as models both sampled in a single vineyard at three dates over a period of two growing years. Highly conserved temporal patterns were found in the two cultivars. Intra-annual changes in microbial community composition were recorded whereas convergent microbial communities were observed on the two September dates. In particular, the increase in Actinobacteria and decrease in Glomeromycota in September were interpreted as shifts in the microbiota community patterns related to plant physiological requirements (e.g. water supply). A high proportion of non-random assembly of the root endospheric bacterial community confirmed the deterministic influence of the plant or/and the environment in microbial recruitment over time. The modified normalized stochasticity ratio (MST) showed that deterministic processes of assembly (MST < 50%) were commonplace despite the changes in the root microbiota composition observed among sampling dates. Our study suggests an intra-annual rhythm of microbiota shifts, marginally random, with a succession within the root-microbiota endosphere likely governed by active plant filtering. A better knowledge of microbial-recruitment at work, seems important for both fundamental and applied perspectives.
Induced polarization (IP) method is one of the geophysical methods that utilizes polarization of subsurface materials. This method is very sensitive to the presence of (semi) conducting materials. Previous studies revealed the underlying mechanisms of metal polarization in simple geometry. However, there is a gap between such studies and the conditions in geological materials. To fill the gap, I have established the simulation method for studying the polarization of metal grains in a three‐dimensional field using the open‐source computational‐fluid‐dynamic software OpenFOAM. The three‐dimensional view of the surface potential distribution on a metal grain clarified how polarization is induced while varying geometrical constrictions. I varied the channel size, the orientation of the anisotropic grain, the elongation of the grain, and the distance of two grains. The results include: (a) a less decay of imaginary potential over distance for shorter or narrower channel, enhanced polarization in narrower channel and reduced polarization in shorter channel, (b) shift of the position of maximum imaginary potential over frequency on the surface of the oriented anisotropic grains, (c) higher peak frequency and larger polarization locally at the edge of the grains for elongated grains, and (d) enhancement of polarization by interaction of nearby grains. The underlying mechanisms were examined for each case. In addition, relationships between each scenario in my simulation and the subsurface environment were discussed. My successful implementation of the simulation for metal grains may be applied to improve the modeling, interpretation, and laboratory experimental setup.
The transfer of toxic cyanobacterial Microcystis blooms from freshwater to estuaries constitutes a serious environmental problem worldwide that is expected to expand in scale and intensity with anthropogenic and climate change. The formation and maintenance of Microcystis in colonial form is conditioned to the presence of extracellular polymeric substances (EPS). In this study, we attempted to better understand how the mucilaginous colonial form of Microcystis evolves under environmental stress conditions. In particular, we studied and compared the production and the composition of EPS fractions (attached and free) from natural colonies of a Microcystis bloom and from a unicellular M. aeruginosa strain under salinity and nutrient stress (representing a land-sea continuum). Our results highlighted a greater production of EPS from the natural colonies of Microcystis than the unicellular one under nutrient and combined stress conditions dominated by the attached form. In comparison to the unicellular Microcystis, EPS produced by the colonial form were characterized by high molecular weight polysaccharides which were enriched in uronic acids and hexosamines, notably for the free fraction in response to increased salinities. This complex extracellular matrix gives the cells the ability to aggregate and allows the colonial cyanobacterial population to cope with osmotic shock.
We have developed an original blue-light mediated ironcatalyzed oxy-phosphinylation of activated alkenes by secondary phosphine oxides under air at room temperature. Various βketophosphine oxides were then obtained in 43-97% isolated yields. Control experiments revealed that radical process is involved in the mechanism.
Idiopathic dilated cardiomyopathy (IDCM) is one of the most common forms of nonischemic cardiomyopathy worldwide, possibly leading to cardiogenic shock (CS). Despite this heavy burden, the outcomes of CS in IDCM are poorly reported. Based on a large registry of unselected CS, our aim was to shed light on the 1-year outcomes after CS in patients with and without IDCM. FRENSHOCK was a prospective registry including 772 patients with CS from 49 centers. The 1-year outcomes (rehospitalizations, mortality, heart transplantation [HTx], ventricular assist devices [VAD]) were analyzed and adjusted on independent predictive factors. Within 772 CS included, 78 occurred in IDCM (10.1%). Patients with IDCM had more frequent history of chronic kidney failure and implantable cardioverter-defibrillator implantation. No difference was found in 1-month all-cause mortality between groups (28.2 vs 25.8%for IDCM and others, respectively; adjusted hazard ratio 1.14 [0.73 to 1.77], p = 0.57). Patients without IDCM were more frequently treated with noninvasive ventilation and intra-aortic balloon pump. At 1 year, IDCM led to higher rates of death or cardiovascular rehospitalizations (adjusted odds ratio 4.77 [95% confidence interval 1.13 to 20.1], p = 0.03) and higher rates of HTx or VAD for patients aged <65 years (adjusted odds ratio 2.68 [1.21 to 5.91], p = 0.02). In conclusion, CS in IDCM is a very common scenario and is associated with a higher rate of 1-year death or cardiovascular rehospitalizations and a more frequent recourse to HTx or VAD for patients aged <65 years, encouraging the consideration of it as a red flag for myocardial decline and urging for a closer follow-up and earlier evaluation for advanced heart failure therapies.
Aims: Impact of skin mottling has been poorly studied in patients admitted for cardiogenic shock. This study aimed to address this issue and identify determinants of 30-day and 1-year mortality in a large cardiogenic shock cohort of all etiologies. Methods and results: FRENSHOCK is a prospective multicenter observational registry conducted in French critical care units between April and October, 2016. Among the 772 enrolled patients (mean age 65.7 ± 14.9 years; 71.5% male), 660 had skin mottling assessed at admission (85.5%) with almost 39% of patients in cardiogenic shock presenting mottling. The need for invasive respiratory support was significantly higher in patients with mottling (50.2% vs. 30.1%, p < 0.001) and likewise for the need for renal replacement therapy (19.9% vs. 12.4%, p = 0.09). However, the need for mechanical circulatory support was similar in both groups. Patients with mottling at admission presented a higher length of stay (19 vs. 16 days, p = 0.033), a higher 30-day mortality rate (31% vs. 23.3%, p = 0.031), and also showed significantly higher mortality at 1-year (54% vs. 42%, p = 0.003). The subgroup of patients in whom mottling appeared during the first 24 h after admission had the worst prognosis at 30 days. Conclusion: Skin mottling at admission in patients with cardiogenic shock was statistically associated with prolonged length of stay and poor outcomes. As a perfusion-targeted resuscitation parameter, mottling is a simple, clinical-based approach and may thus help to improve and guide immediate goal-directed therapy to improve cardiogenic shock patients' outcomes.
bold xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Background: Following previous professional communication research into entrepreneurship, we examine key genres of a specific business accelerator, Start-Up Chile (SUP). Through a triangulated study of interviews, texts, and videos, we examine how the Playbook serves as a regulatory metagenre that represents the SUP experience to the participating firms. We find that aspects of the Playbook's representation are at odds with the other data, divergences that we argue emerge from a broader tension among SUP's stakeholders and goals. Literature review: We review the professional communication literature on entrepreneurship, literature on startups and accelerators, and on writing, activity, and genre research (WAGR). Specifically, we examine WAGR research on metagenres and professional identity formation. Research question: How does this successful international accelerator regularize the learning experience of its exceedingly diverse startups? Specifically, how does SUP regulate the startups' different experiences, reframing the experience of entrepreneurship and teaching these startups to form their professional identity as entrepreneurs? Research methodology: We structured this research as a qualitative case study of SUP. Data included documents, videos, interviews, and social media. We triangulated these data sources to identify points of convergence (in which different data sources supported the same assertions) and divergence (in which data sources contradicted each other). Results: SUP provides the Playbook and Newsletter as metagenres that regulate complex interactions among other genres and events, guiding firms into having roughly equivalent experiences as well as maintaining relationships among volunteers such as mentors. But the Playbook also reframes the experience of entrepreneurship so that it can fit into SUP's program: it reframes the cyclical entrepreneurship process as linear, and it reframes promises of future action as tracking of past actions. In undergoing these experiences, the startups form their professional identity as entrepreneurs. Conclusion: We conclude by discussing implications for accelerators as well as for how professional communication genres and metagenres regulate neophytes’ experiences in training programs more broadly.
The ever-growing complexity of radiating systems asks for always more challenging radiation pattern characterizations requiring time consuming field acquisitions and high-cost facilities. Consequently phaseless, or magnitude-only, measurements have recently regained of interest as they prevent the tedious and difficult task of phase acquisition. Consequently, it allows the use of cheaper or more versatile measurement setups like drone measurements or easier high-frequency measurements. However, the difficulty is shifted to the notoriously difficult resolution of the phase retrieval problem, which instability is commonly mitigated by the acquisition of a large number of phaseless field samples. A procedure enabling a reliable and accurate phaseless antenna measurement from a reduced number of spherical NF samples based on the two scan technique is proposed. Its efficiency and stability, that relies on the systematic determination of a good starting point, is validated by representative simulations and experimental cases performed on various antenna structures.
The all-solid-state sodium battery has emerged as a promising candidate for energy storage. However, the limited electrochemical stability of the solid electrolyte, particularly in the presence of Na metal at the anode, along with low ionic conductivity, hinders its widespread application. In this work, the design of P and O elements in Na3SbS4 solid electrolyte was investigated through a series of structural tests and characterizations. The electrochemical stability was remarkably improved in the Na/Na3SbP0.16S3.6O0.4/Na battery, exhibiting a stability of 260 h under a current of 0.1 mA cm-2. Additionally, the room temperature conductivity of Na3SbP0.16S3.6O0.4 was enhanced to 3.82 mS cm-1, maintaining a value comparable to commercial standards. The proposed design strategy provides an approach for developing sodium ion solid-state batteries with high energy density and long lifespan. The stability of the solid electrolyte interface at the Na | solid electrolyte interface proves critical for the successful assembly of all-solid-state sodium ion batteries.
Reaction fronts sustained by fluid mixing play a central role in a large range of porous media systems and applications. In many cases, pointwise continuous injection of a reactant that displaces a resident reactant in three dimensions leads to a growing spherical reaction front. While such configurations have until now been studied under the assumption of a constant diffusion coefficient, in porous media the dominant diffusive process at the continuum scale is hydrodynamic dispersion, which depends linearly on the flow velocity. Here we analyze the impact of this nonuniform and time-varying hydrodynamic dispersion on reactive transport occurring in such a spherically advected reaction front under point injection and at constant flow rate. During an initial transient regime, dispersion leads to a more advanced reaction front and a larger global reaction rate than when molecular diffusion is the only mixing process, as well as to different temporal scalings for the reaction front properties. At larger times, the reaction front eventually reaches a steady state, characterized by a static position and time-independent reactant concentrations and reaction rate, regardless of the presence and strength of dispersion. When dispersion is weak, the steady-state front is positioned in a region where dispersion is negligible compared to diffusion. Conversely, when dispersion is large, the steady-state front is positioned in the transition zone where dispersion and diffusion are comparable. Under this condition, hydrodynamic dispersion permanently affects the reaction front's transport by altering the steady state itself and augmenting the global reaction rate.
The technology of reconfigurable intelligent surfaces (RISs) has been showing promising potential in a variety of applications relying on Beyond-5G networks. RIS can indeed provide fine channel flexibility to improve communication quality of service (QoS) or restore localization capabilities in challenging operating conditions, while conventional approaches fail (e.g., due to insufficient infrastructure, severe radio obstructions). In this paper, we tackle a general low-complexity approach for optimizing the precoders that control such reflective surfaces under hardware constraints. More specifically, it allows the approximation of any desired beam pattern using a pre-characterized lookup table of feasible complex reflection coefficients for each RIS element. The proposed method is first evaluated in terms of beam fidelity for several examples of RIS hardware prototypes. Then, by means of a theoretical bounds analysis, we examine the impact of RIS beams approximation on the performance of near-field downlink positioning in non-line-of-sight conditions, while considering several RIS phase profiles (including directional, random and localization-optimal designs). Simulation results in a canonical scenario illustrate how the introduced RIS profile optimization scheme can reliably produce the desired RIS beams under realistic hardware limitations. They also highlight its sensitivity to both the underlying hardware characteristics and the required beam kinds in relation to the specificity of RIS-aided localization applications.
The characteristics and fate of cancer cells partly depend on their environmental stiffness, i.e., the local mechanical cues they face. HepaRG progenitors are liver carcinoma cells exhibiting transdifferentiation properties; however, the underlying mechanisms remain unknown. To evaluate the impact of external physical forces mimicking the tumor microenvironment, we seeded them at very high density for 20 h, keeping the cells round and unanchored to the substrate. Applied without corticoids, spatial confinement due to very high density induced reprogramming of HepaRG cells into stable replicative stem-like cells after replating at normal density. Redifferentiation of these stem-like cells into cells very similar to the original HepaRG cells was then achieved using the same stress but in the presence of corticoids. This demonstrates that the cells retained the memory required to run the complete hepatic differentiation program, after bypassing the Hayflick limit twice. We show that physical stress improved chromosome quality and genomic stability, through greater efficiency of DNA repair and restoration of telomerase activity, thus enabling cells to escape progression to a more aggressive cancer state. We also show the primary importance of high-density seeding, possibly triggering compressive stress, in these processes, rather than that of cell roundness or intracellular tensional signals. The HepaRG-derived lines established here considerably extend the lifespan and availability of this surrogate cell system for mature human hepatocytes. External physical stress is a promising way to create a variety of cell lines, and it paves the way for the development of strategies to improve cancer prognosis.
We report herein on the self‐assembling features, chiroptical activity, and spin filtering properties of 2,15‐ and 4,13‐disubstituted [6]helicenes decorated in their periphery with 3,4,5‐tris(dodecyloxy)‐N‐(4‐ethynylphenyl)benzamide moieties. The weak non‐covalent interaction between these units conditions the corresponding circularly polarized luminescence and spin polarization. The self‐assembly is overall weak for these [6]helicene derivatives that, despite the formation of H‐bonding interactions between the amide groups present in the peripheral moieties, shows very similar chiroptical properties both in the monomeric or aggregated states. This effect could be explained by considering the steric effect that these groups could generate in the growing of the corresponding aggregate formed. Importantly, the self‐assembling features also condition chiral induced spin selectivity (CISS effect), with experimental spin polarization (SP) values found between 35‐40% for both systems, as measured by magnetic‐conducting atomic force microscopy (AFM) technique.
During percutaneous coronary intervention, the guiding catheter plays an important role. Tracking the catheter tip placed at the coronary ostium in the X-ray fluoroscopy sequence can obtain image displacement information caused by the heart beating, which can help dynamic coronary roadmap overlap on X-ray fluoroscopy images. Due to a low exposure dose, the X-ray fluoroscopy is noisy and low contrast, which causes some difficulties in tracking. In this paper, we developed a new catheter tip tracking framework. First, a lightweight efficient catheter tip segmentation network is proposed and boosted by a self-distillation training mechanism. Then, the Bayesian filtering post-processing method is used to consider the sequence information to refine the single image segmentation results. By separating the segmentation results into several groups based on connectivity, our framework can track multiple catheter tips. The proposed tracking framework is validated on a clinical X-ray sequence dataset.
Background and aims: Benefit of tricuspid regurgitation (TR) correction and timing of intervention are unclear. This study aimed to compare survival rates after surgical or transcatheter intervention to conservative management according to TR clinical stage as assessed using the TRI-SCORE. Methods: 2,413 patients with severe isolated functional TR were enrolled in TRIGISTRY (1217 conservatively managed, 551 isolated tricuspid valve surgery and 645 transcatheter valve repair). The primary endpoint was survival at 2 years. Results: The TRI-SCORE was low (≤3) in 32%, intermediate (4-5) in 33% and high (≥6) in 35%. A successful correction was achieved in 97% and 65% of patients in the surgical and transcatheter groups, respectively. Survival rates decreased with the TRI-SCORE in the three treatment groups (all P < 0.0001). In the low TRI-SCORE category, survival rates were higher in the surgical and transcatheter groups than in the conservative management group (93%, 87% and 79%, respectively; P = 0.0002). In the intermediate category, no significant difference between groups was observed overall (80%, 71% and 71%, respectively; P = 0.13) but benefit of the intervention became significant when the analysis was restricted to patients with successful correction (80%, 81% and 71%, respectively; P = 0.009). In the high TRI-SCORE category, survival was similar between groups even when restricted to patients with successful correction (61%, 68% and 58% respectively, P = 0.08). Conclusion: Survival progressively decreased with the TRI-SCORE irrespective of treatment modality. Compared to conservative management, an early and successful surgical or transcatheter intervention improved 2-year survival in patients at low and, to a lower extent, intermediate TRI-SCORE, while no benefit was observed in the high TRI-SCORE category.
Transition zones between natural and human-altered spaces are eroding in most terrestrial ecosystems. The persistence of animals in shared landscapes depends in part on their behavioral flexibility, which may involve being able to exploit human agricultural production. As a forest-dependent species, the Barbary macaque (Macaca sylvanus) is affected by the progressive conversion of forest-adjacent lands into crops. We explore how Barbary macaque behavior differs between groups living in a forest at the edge of agricultural zones (hereafter "disturbed groups") and groups inhabiting undisturbed forests (hereafter "natural groups"). We compare the diets, activity-budgets, home range sizes, daily path lengths, and sleeping site locations of the groups. We also quantify anthropogenic disturbances (i.e., rates of encounter with humans and dogs) and investigate relationships between such disturbances and the diets and activity budgets of macaques through multiple co-inertia analysis. Disturbed groups included high proportions of cultivated food items in their diet and encountered over 0.5/h anthropogenic disturbances. Activity-budgets differed between disturbed and natural groups and were mostly influenced by diets, not anthropogenic disturbances. Disturbed groups spent more time feeding and less time resting than natural ones. Patterns of space use differed markedly between groups, with disturbed groups displaying smaller home ranges, shorter daily path length, and much higher reutilization of sleeping sites than natural groups. This study highlights the dietary and behavioral flexibility of Barbary macaques living in human-altered environments. Their patterns of space use suggest a reduction in energy expenditure in the disturbed groups due to the inclusion of cultivated food items in their diet possibly leading to increased foraging efficiency. However, the high rates of anthropogenic encounters, including aggressive ones, are likely stressful and may potentially induce extra energy costs and lead to macaque injuries. This could result in demographic costs for crop-foraging groups, threatening the conservation of this endangered species.
For over a decade, the French mission ‘Archaeology of the Arabian Seashores’ has been exploring the evolution of the Omani coastline, from hunter–gatherers to the rise of complex societies during the crucial passages from the culmination of the Pleistocene to the Early Bronze Age, passing through the Neolithic. The team extensively surveyed the land spreading from the eastern head of Arabia, Ra's al‐Hadd and Ra's al‐Jinz, to the last villages of Dhofar, including Masirah Island and the Hallaniyyat archipelago, covering 1000 km. Most Final Palaeolithic, Neolithic and Early Bronze Age sites were tested or excavated. A multidisciplinary approach that involves the joint work of archaeologists and geologists was chosen to include the contribution of environmental factors to modifying the equilibriums between the natural environment and human communities through the study of climatic and eustatic fluctuations. The project provided a substantive perspective on the evolution of maritime communities between 10,000 and 2000 bce. Moreover, an interdisciplinary and multiscalar approach for describing and analysing the change in the material culture of this region made it possible to transcend the traditional typology and examine the role of human communities’ interaction.
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Kirthana Kunikullaya
  • IRSET - Institut de Recherche en Santé, Environnement et Travail - INSERM Unité 1085
Nicolas Bigot
  • UMR CNRS 6290 - Institut de Génétique et Développement de Rennes (IGDR)
Rennes, France