Aerodynamic and acoustic analysis of an optimized low Reynolds number rotor

The demand in Micro–Air Vehicles (MAV) is increasing as well as their potential missions. Either for discretion in military operations or noise pollution in civilian use, noise reduction of MAV is a goal to achieve. Aeroacoustic research has long been focusing on full scale rotorcraft. At MAV scales however, the hierarchization of the numerous sources of noise is not straightforward, as a consequence of the relatively low Reynolds number that ranges typically from 5 000 to 100 000. This knowledge however, is crucial for aeroacoustic optimization. This contribution briefly describes a low–cost, numerical methodology to achieve noise reduction by optimization of MAV rotor blade geometry. That methodology is applied to reduce noise from a MAV developed at ISAE–SUPAERO and a 8 dB(A) reduction on the acoustic power is found experimentally. The innovative rotor blade geometry allowing this noise reduction is then analyzed in detail using high–fidelity numerical approaches such as Unsteady Reynolds Averaged Navier–Stokes (URANS) simulation and Large Eddy Simulation using Lattice Boltzmann Method (LES–LBM). That strategy gives insight into the flow features around the optimized rotor and guidelines for the acoustic models used in a low–cost numerical optimization loo

Global transpiration data from sap flow measurements : the SAPFLUXNET database

Plant transpiration links physiological responses of vegetation to water supply and demand with hydrological, energy, and carbon budgets at the land-atmosphere interface. However, despite being the main land evaporative flux at the global scale, transpiration and its response to environmental drivers are currently not well constrained by observations. Here we introduce the first global compilation of whole-plant transpiration data from sap flow measurements (SAPFLUXNET, https://sapfluxnet.creaf.cat/, last access: 8 June 2021). We harmonized and quality-controlled individual datasets supplied by contributors worldwide in a semi-automatic data workflow implemented in the R programming language. Datasets include sub-daily time series of sap flow and hydrometeorological drivers for one or more growing seasons, as well as metadata on the stand characteristics, plant attributes, and technical details of the measurements. SAPFLUXNET contains 202 globally distributed datasets with sap flow time series for 2714 plants, mostly trees, of 174 species. SAPFLUXNET has a broad bioclimatic coverage, with woodland/shrubland and temperate forest biomes especially well represented (80 % of the datasets). The measurements cover a wide variety of stand structural characteristics and plant sizes. The datasets encompass the period between 1995 and 2018, with 50 % of the datasets being at least 3 years long. Accompanying radiation and vapour pressure deficit data are available for most of the datasets, while on-site soil water content is available for 56 % of the datasets. Many datasets contain data for species that make up 90 % or more of the total stand basal area, allowing the estimation of stand transpiration in diverse ecological settings. SAPFLUXNET adds to existing plant trait datasets, ecosystem flux networks, and remote sensing products to help increase our understanding of plant water use, plant responses to drought, and ecohydrological processes. SAPFLUXNET version 0.1.5 is freely available from the Zenodo repository (https://doi.org/10.5281/zenodo.3971689; Poyatos et al., 2020a). The "sapfluxnetr" R package - designed to access, visualize, and process SAPFLUXNET data - is available from CRAN.Peer reviewe

: Le dysfonctionnement du " brain-gut "

International audienceThere is a bidirectional relation between the central nervous system and the digestive tract, i.e., the brain-gut axis. Numerous data argue for a dysfunction of the brain-gut axis in the pathophysiology of irritable bowel syndrome (IBS). Visceral hypersensitivity is a marker of IBS as well as of an abnormality of the brain-gut axis. This visceral hypersensitivity is peripheral and/or central in origin and may be the consequence of digestive inflammation or an anomaly of the nociceptive message treatment at the spinal and/or supraspinal level. Stress is involved in the genesis and maintenance of IBS. Disturbances of the autonomic nervous system are observed in IBS as a consequence of brain-gut axis dysfunction. The contribution of the neurosciences, in particular brain imaging techniques, has contributed to the better understanding of IBS physiopathology. The better knowledge of brain-gut axis dysfunction has therapeutic implications, either through drugs and/or cognitive and behavioral therapies

Thermal grill illusion of pain in patients with chronic pain: a clinical marker of central sensitization?

International audienceThe thermal grill illusion of pain (TGIP) is a paradoxical burning pain sensation elicited by the simultaneous application of innocuous cutaneous warm and cold stimuli with a thermode ("thermal grill") consisting of interlaced heated and cooled bars. Its neurophysiological mechanisms are unclear, but TGIP may have some mechanisms in common with pathological pain, including central sensitization in particular, through the involvement of N-methyl-d-aspartate receptors. However, few studies have investigated TGIP in patients with chronic pain and its clinical relevance is uncertain. We hypothesized that the TGIP would be increased in comparison with controls in patients with fibromyalgia or irritable bowel syndrome, which are regarded as typical "nociplastic" primary pain syndromes related to changes in central pain processing. We compared the sensations elicited by a large range of combinations of temperature differentials between the warm and cold bars of a thermal grill applied to the hand between patients with fibromyalgia (n = 30) or irritable bowel syndrome (n= 30) and controls (n = 30). The percentage of TGIP responses and the intensity and unpleasantness of TGIP were significantly greater in patients than controls. Furthermore, positive correlations were found between TGIP intensity and clinical pain intensity and between TGIP intensity and the cold pain threshold measured on the hand. These results are consistent with our working hypothesis of shared mechanisms between TGIP and clinical pain mechanisms in patients with nociplastic chronic pain syndromes and suggest that TGIP might represent a clinical marker of central sensitization in these patients

Aerodynamic and acoustic analysis of an optimized low Reynolds number rotor

International audienceThe demand in Micro-Air Vehicles (MAV) is increasing as well as their potential missions. Either for discretion in military operations or noise pollution in civilian use, noise reduction of MAV is a goal to achieve. Aeroacoustic research has long been focusing on full scale rotorcrafts. At MAV scales however, the hierarchization of the numerous sources of noise is not straightforward, as a consequence of the relatively low Reynolds number that ranges typically from 5,000 to 100,000. is knowledge however, is crucial for aeroacoustic optimization. is contribution briefly describes a low-cost, numerical methodology to achieve noise reduction by optimization of MAV rotor blade geometry. That methodology is applied to reduce noise from a MAV developped at ISAE-Supaero and a 8 dB(A) reduction on the acoustic power is found experimentally. The innovative rotor blade geometry allowing this noise reduction is then analyzed in detail using high-fidelity numerical approaches such as Unsteady Reynolds Averaged Navier-Stokes (URANS) simulation and Very Large Eddy Simulation using La ice Boltzmann Method (VLES-LBM). at strategy gives insight into the flow features around the optimized rotor and guidelines for the acoustic models used in a low-cost numerical optimization loop

Fermentable Oligo-, Di-, and Mono-Saccharides and Polyols (FODMAPs) Consumption and Irritable Bowel Syndrome in the French NutriNet-Santé Cohort

International audience(1) Background: Specific foods, and more particularly, fermentable oligo-, di-, and mono-saccharides and polyols (FODMAPs) are often considered as triggers of digestive symptoms in Irritable Bowel Syndrome (IBS). Our aim was to study FODMAP consumption in controls and IBS participants in a large French population-based cohort; (2) Methods: Participants from the NutriNet-Santé cohort study completed the Rome IV and IBS-SSS questionnaire in a cross sectional study. Among them, 27,949 eligible participants had previously completed three 24-h recalls as well as anthropometrics, socio-demographical and lifestyle data. Total FODMAP intake (in g/day) was computed using a specific composition table. The association between FODMAPs and IBS was estimated through multivariable logistic regression models; (3) Results: Included participants were mainly women (75.4%) and the mean age was 43.4 ± 14.1 years. FODMAPs accounted for a mean daily intake of 19.4 ± 9.5 g/day. Overall 1295 participants (4.6%) were identified with an IBS. After adjusting for confounding factors, IBS participants had lower intakes in FODMAPs than non-IBS ones (aOR: 0.88, 95% CI: 0.82–0.95, p-value: 0.001). IBS severity was associated with more frequent low FODMAP intakes (<9 g/day); (4) Conclusions: Participants tended to consume 19 g of FODMAPs per day, but slightly less for IBS participants than for controls. In IBS participants, higher severity was associated with lower intakes

Relationship between rectal sensitivity, symptoms intensity and quality of life in patients with irritable bowel syndrome.: rectal sensitivity, IBS severity and QoL

International audienceBACKGROUND: Relationships between pain threshold during rectal distension and both symptoms intensity and alteration in quality of life (QoL) in irritable bowel syndrome (IBS) patients have been poorly evaluated. AIM: To evaluate relationships between rectal sensitivity, IBS symptom intensity and QoL in a multicentre prospective study. METHODS: Rectal threshold for moderate pain was measured during rectal distension in IBS patients (Rome II), while IBS symptoms intensity was assessed by a validated questionnaire and QoL by the Functional Digestive Disorder Quality of Life questionnaire. RESULTS: Sixty-eight patients (44.2 +/- 12.7 years, 48 women) were included. The mean rectal distending volume for moderate pain was 127 +/- 35 mL while 45 patients (66%) had rectal hypersensitivity (pain threshold <140 mL). Rectal threshold was not significantly related either to overall IBS intensity score (r = -0.66, P = 0.62) or to its different components, or to FDDQL score (r = 0.30, P = 0.14). Among FDDQL domains, only anxiety (r = 0.30, P = 0.01) and coping (r = 0.31, P = 0.009) were significantly related with pain threshold. CONCLUSIONS: In this study, two-thirds of IBS patients exhibited rectal hypersensitivity. No significant correlation was found between rectal threshold and either symptom intensity or alteration in QoL