Modelling Nitrogen Uptake in Winter Oilseed Rape by Using Influx Kinetics of Nitrate Transport Systems

A mechanistic model was proposed in order to predict nitrogen uptake by a culture of oilseed rape (Brassica napus L.), using independently measured characteristics of plants growing in hydroponic or under field conditions. Uptake kinetics of the different components (Constitutive and Inducible) of the Low and High Affinity Transport Systems of nitrate (CLATS, ILATS, CHATS and IHATS, respectively) were determined by 15NO3- labelling in controlled conditions. The use of kinetic equations of transport systems and the experimental field data from the INRA-Châlons rape databank allowed to model NO3- uptake during the plant growth cycle. The study of different factors such as root temperature, day/night cycle and ontogenetic stages on NO3- uptake rate has been undertaken in order to improve the model prediction. Model outputs show that the high affinity transport system (HATS) accounted for about 90 % of total NO3- uptake (20 and 70 % for CHATS and IHATS without fertilization, respectively). The low affinity transport system (LATS) accounted for a minor proportion of total N uptake, and its activity was restricted to the early phase of the growth cycle. However, N autumnal fertilization increased the duration of its contribution (from 67 to 100 days) to total N uptake

Determining the crystallographic orientation of hexagonal crystal structure materials with surface acoustic wave velocity measurements

© 2020 Throughout our engineered environment, many materials exhibit a crystalline lattice structure. The orientation of such lattices is crucial in determining functional properties of these structures, including elasticity and magnetism. Hence, tools for determining orientation are highly sought after. Surface acoustic wave velocities in multiple directions can not only highlight the microstructure contrast, but also determine the crystallographic orientation by comparison to a pre-calculated velocity model. This approach has been widely used for the recovery of orientation in cubic materials, with accurate results. However, there is a demand to probe the microstructure in anisotropic crystals - such as hexagonal close packed titanium. Uniquely, hexagonal structure materials exhibit transverse isotropic linear elasticity. In this work, both experimental and simulation results are used to study the discrete effects of both experimental parameters and varying lattice anisotropy across the orientation space, on orientation determination accuracy. Results summarise the theoretical and practical limits of hexagonal orientation determination by linear SAW measurements. Experimental results from a polycrystalline titanium specimen, obtained by electron back scatter diffraction and spatially resolved acoustic spectroscopy show good agreement (errors of ϕ1=5.14° and Φ=6.99°). Experimental errors are in accordance with those suggested by simulation, according to the experimental parameters. Further experimental results demonstrate dramatically improved orientation results (Φ erro

Neuropathic complications after 157 procedures of continuous popliteal nerve block for hallux valgus surgery. A retrospective study

SummaryBackgroundContinuous peripheral nerve block (CPNB), in particular at the popliteal fossa, is widely used in orthopedic surgery, allowing good postoperative analgesia. Possible neuropathic complications, however, remain poorly known.ObjectiveTo review the characteristics of peripheral neuropathy (PN) after sciatic CPNB at the popliteal fossa, estimating prevalence, severity, evolution and possible risk factors, especially those relating to the procedure.MethodsRetrospective study of PN associated with popliteal fossa CPNB for hallux valgus surgery, between November 1st, 2005 and November 1st, 2009. All procedures were analyzed (type of anesthesia, approach, nerve location technique, number of procedures by operator) with, for each case of PN, analysis of clinical and electromyographic data.ResultsOne hundred and fifty seven sciatic CPNBs were performed (92% women; mean age, 55 years). The approach was lateral (n=62), posterior (n=74) or unknown (n=21). Ultrasound guidance was combined to neurostimulation for 69 patients (44%). Three women (prevalence=1.91%), aged 19, 24 and 65 years respectively, developed associated common superficial peroneal and sural nerve injury (2), axonal on electromyography, with motor (n=1) and/or sensory (n=3) residual dysfunction.DiscussionThe higher prevalence found in the present study than in the literature (0 to 0.5%) raises questions of methodological bias or technical problems. The common peroneal and sural nerves seem to be exposed, unlike the tibial. Several mechanisms can be suggested: anesthetic neurotoxicity, direct mechanical lesion, or tourniquet-related ischemia and conduction block. Further studies are necessary to determine the ideal anesthetic procedure.ConclusionPatients should be informed of the potential risk, however rare, even during mild surgery. The best possible technique should be implemented, with reinforced surveillance.Level of evidenceLevel IV retrospective study

On three-dimensional misorientation spaces.

Determining the local orientation of crystals in engineering and geological materials has become routine with the advent of modern crystallographic mapping techniques. These techniques enable many thousands of orientation measurements to be made, directing attention towards how such orientation data are best studied. Here, we provide a guide to the visualization of misorientation data in three-dimensional vector spaces, reduced by crystal symmetry, to reveal crystallographic orientation relationships. Domains for all point group symmetries are presented and an analysis methodology is developed and applied to identify crystallographic relationships, indicated by clusters in the misorientation space, in examples from materials science and geology. This analysis aids the determination of active deformation mechanisms and evaluation of cluster centres and spread enables more accurate description of transformation processes supporting arguments regarding provenance