Dense granular flow around a penetrating object: Experiments and hydrodynamic model

We present in this Letter experimental results on the bidimensional flow field around a cylinder penetrating into dense granular matter together with drag force measurements. A hydrodynamic model based on extended kinetic theory for dense granular flow reproduces well the flow localization close to the cylinder and the corresponding scalings of the drag force, which is found to not depend on velocity, but linearly on the pressure and on the cylinder diameter and weakly on the grain size. Such a regime is found to be valid at a low enough "granular" Reynolds number.Comment: 5 pages, 4 figure

Microbiome of the Cool Season Forage Grass Timothy (\u3ci\u3ePhleum pratense\u3c/i\u3e L.) and Its Potential Role in Stress Tolerance

The functional attributes of the microbiome associated with timothy for growth promotion properties, antimicrobial and biosurfactant capacities were characterized. A total of 254 culturable bacteria were identified by 16S rRNA sequencing and grouped into 16 taxa that shared high homology of 98–99% with other known sequences. The majority of bacterial isolates exhibited multifunctional growth promotion attributes and plant stress improvement. The selection of competent and compatible strains for application in forage production is dependent on the recognition of root exudates and motility towards the roots, attachment to the root surface, formation of biofilm, penetration, and colonization of internal tissues. We selected competent rhizospheric bacteria to generate a multispecies consortium made of three strains that displayed growth-promoting abilities in timothy through the production of IAA, volatile organic compounds that increased root biomass, the production of siderophores and antibiotic resistance, as well as the ability to colonize plants. This study demonstrated that the multispecies consortium displayed biofilm formation and chemotactic behaviour towards several organic acids and towards root exudates released from the model grass Brachypodium distachyon. Organic acids were successful in stimulating the formation of biofilm of the multispecies consortium. In particular, fumaric and malic acids enhanced selective recruitment of the multispecies consortium in a dose-dependent manner thereby, promoting biofilm formation on root surface as demonstrated in SEM micrographs. The multispecies consortium exhibited biofilm-related traits including the production of exopolysaccharides (EPS) and alginate. EPS amounts were comparable in single strains and consortium forms and alginate production increased by 160% when the consortium was subjected to drought stress. These findings demonstrated that plant-microbe interaction is the hub of various factors directly affecting this balanced dual relation and that root exudates could be very selective in recruiting highly qualified multispecies consortium

Effects of Insecticide and Tolerant Alfalfa Cultivars on Potato Leafhopper (\u3cem\u3eEmpoasca fabae\u3c/em\u3e) Populations and Forage Yields in Quebec (Canada)

The potato leafhopper [PLH, Empoasca fabae (Harris)], which affects several crops including alfalfa (Medicago sativa L.), is a recurrent problem in several regions of Quebec. The objective was to evaluate alfalfa management tools in order to reduce yield losses caused by this pest. An experiment was conducted at two sites in Quebec over three field seasons to evaluate the impact of insecticide applications and the use of PLHtolerant cultivars on forage yield and PLH populations. Foliar insecticide applications in the seeding year reduced PLH populations but generally failed to impact alfalfa yields compared to untreated alfalfa. However, in one experiment at one site, applications done in the seeding year resulted in increased first-cut alfalfa yields in the post-seeding year compared to untreated alfalfa, even if PLH populations were low. Differences in yields between PLH-tolerant and PLH-susceptible cultivars were minimal in the seeding and post-seeding years regardless of the PLH population levels. However, two PLH-tolerant cultivars produced lower yields compared to other cultivars in the post-seeding year at one site. Preliminary results suggest that foliar insecticide applications could be a more effective way to reduce PLH populations than PLH-tolerant cultivars. However, more data will be required to confirm these results and determine the impact of these management tools on alfalfa yields

Estimation of the diameter and cross-sectional area of the internal jugular veins in adult patients

International audienceINTRODUCTION: Unawareness of an asymmetry between the right and left internal jugular vein (IJV) and methodological pitfalls in previous studies raise concerns about such asymmetry. Hence the aim of this prospective non-interventional study was to validate the hypothesis that right IJV diameter is greater than those of left IJV and to determine the cross-sectional area of the IJVs using computed tomography (CT)-scans and original automatic software. METHODS: All consecutive adult outpatients who underwent a thoracic contrast-enhanced (TCE) helical CT-scan during a 5-month period were included. To determine diameter and cross sectional area of the IJVs, we used Advanced Vessel Analysis software integrated in a CT-scan (Advanced Vessel Analysis on Advantage Workstation Windows 4.2; General Electrics) allowing automatic segmentation of vessels and calculation of their diameters and cross-sectional areas. RESULTS: A total of 360 TCE CT-scans was performed; 170 were excluded from the analysis. On the remaining 190 CT scans, the diameter and cross-sectional area of the right IJV were significantly greater than those of the left IJV (17 +/- 5 mm [median: 17 mm, range: 13 to 20 mm] vs. 14 +/- 5 mm [median: 13 mm, range: 10 to 16 mm], P < 0.001; and 181 +/- 111 mm2 [median: 160 mm2, range: 108 to 235 mm2] vs. 120 +/- 81 mm2 [median: 102 mm2, range: 63 to 168 mm2], P < 0.001, respectively). CONCLUSIONS: In a general population of adult outpatients, the diameter and cross-sectional area of the right IJV were significantly greater than those of the left IJV. This could be an additional argument to prefer right over left IJV cannulation

Dopexamine and norepinephrine versus epinephrine on gastric perfusion in patients with septic shock: a randomized study [NCT00134212]

INTRODUCTION: Microcirculatory blood flow, and notably gut perfusion, is important in the development of multiple organ failure in septic shock. We compared the effects of dopexamine and norepinephrine (noradrenaline) with those of epinephrine (adrenaline) on gastric mucosal blood flow (GMBF) in patients with septic shock. The effects of these drugs on oxidative stress were also assessed. METHODS: This was a prospective randomized study performed in a surgical intensive care unit among adults fulfilling usual criteria for septic shock. Systemic and pulmonary hemodynamics, GMBF (laser-Doppler) and malondialdehyde were assessed just before catecholamine infusion (T(0)), as soon as mean arterial pressure (MAP) reached 70 to 80 mmHg (T(1)), and 2 hours (T(2)) and 6 hours (T(3)) after T(1). Drugs were titrated from 0.2 μg kg(-1 )min(-1 )with 0.2 μg kg(-1 )min(-1 )increments every 3 minutes for epinephrine and norepinephrine, and from 0.5 μg kg(-1 )min(-1 )with 0.5 μg kg(-1 )min(-1 )increments every 3 minutes for dopexamine. RESULTS: Twenty-two patients were included (10 receiving epinephrine, 12 receiving dopexamine–norepinephrine). There was no significant difference between groups on MAP at T(0), T(1), T(2), and T(3). Heart rate and cardiac output increased significantly more with epinephrine than with dopexamine–norepinephrine, whereas. GMBF increased significantly more with dopexamine–norepinephrine than with epinephrine between T(1 )and T(3 )(median values 106, 137, 133, and 165 versus 76, 91, 90, and 125 units of relative flux at T(0), T(1), T(2 )and T(3), respectively). Malondialdehyde similarly increased in both groups between T(1 )and T(3). CONCLUSION: In septic shock, at doses that induced the same effect on MAP, dopexamine–norepinephrine enhanced GMBF more than epinephrine did. No difference was observed on oxidative stress

Dense flow around a sphere moving into a cloud of grains

A bidimensional simulation of a sphere moving at constant velocity into a cloud of smaller spherical grains without gravity is presented with a non-smooth contact dynamics method. A dense granular “cluster” zone of about constant solid fraction builds progressively around the moving sphere until a stationary regime appears with a constant upstream cluster size that increases with the initial solid fraction ϕ0 of the cloud. A detailed analysis of the local strain rate and local stress fields inside the cluster reveals that, despite different spatial variations of strain and stresses, the local friction coeffcient μ appears to depend only on the local inertial number I as well as the local solid fraction ϕ, which means that a local rheology does exist in the present non parallel flow. The key point is that the spatial variations of I inside the cluster does not depend on the sphere velocity and explore only a small range between about 10−2 and 10−1. The influence of sidewalls is then investigated on the flow and the forces