Seasonal switchgrass ecotype contributions to soil organic carbon, deep soil microbial community composition and rhizodeposit uptake during an extreme drought

The importance of rhizodeposit C and associated microbial communities in deep soil C stabilization is relatively unknown. Phenotypic variability in plant root biomass could impact C cycling through belowground plant allocation, rooting architecture, and microbial community abundance and composition. We used a pulse-chase 13C labeling experiment with compound-specific stable-isotope probing to investigate the importance of rhizodeposit C to deep soil microbial biomass under two switchgrass ecotypes (Panicum virgatum L., Kanlow and Summer) with contrasting root morphology. We quantified root phenology, soil microbial biomass (phospholipid fatty acids, PLFA), and microbial rhizodeposit uptake (13C-PLFAs) to 150 cm over one year during a severe drought. The lowland ecotype, Kanlow, had two times more root biomass with a coarser root system compared to the upland ecotype, Summer. Over the drought, Kanlow lost 78% of its root biomass, while Summer lost only 60%. Rhizosphere microbial communities associated with both ecotypes were similar. However, rhizodeposit uptake under Kanlow had a higher relative abundance of gram-negative bacteria (44.1%), and Summer rhizodeposit uptake was primarily in saprotrophic fungi (48.5%). Both microbial community composition and rhizodeposit uptake shifted over the drought into gram-positive communities. Rhizosphere soil C was greater one year later under Kanlow due to turnover of unlabeled structural root C. Despite a much greater root biomass under Kanlow, rhizosphere δ13C was not significantly different between the two ecotypes, suggesting greater microbial C input under the finer rooted species, Summer, whose microbial associations were predominately saprotrophic fungi. Ecotype specific microbial communities can direct rhizodeposit C flow and C accrual deep in the soil profile and illustrate the importance of the microbial community in plant strategies to survive environmental stress such as drought

Application of image analysis to the identification and rating of road surface distress

peer reviewedNumerical image analysis is used to detect narrow cracks on bituminous pavement. This problem is complicated because of the variable road aspect, which depends on coarseness textures, changing ambient lighting, presence of humidity and because of the poor contrast of the cracks with regard to road texture. The paper presents algorithms suited to detect random cracks edges in a noisy environment in three stages. The pre-treatment consisted mainly in applying a background correction to eliminate the heterogeneity due to humidity, shade, ... In the treatment, a threshold value was applied to segment the 'object' from the rest of the image. As these objects may be cracks, part cracks, or some noise erroneously segmented as defect, a post-treatment was applied to appreciate more accurately if a pixel belonged to an object or to the background. It aimed also to assembly parts of the cracks in continuous structure. When compared to visual detection, efficient detection of cracks is obtained. Further work needs to be done to get an automatic detection of the cracks whatever the road texture

Performance Assessment of Kinematics and Control Interfaces for Laparoscope

Which laparoscope positioner is the most efficient? Simple question but still no accurate answer, nearly twenty years after the introduction of AESOP, the first robot that could hold and move the endoscope and camera used in minimally invasive laparoscopic surgery. Metrics and methodologies to measure the performance of industrial robots are defined by international standards (e.g. ISO 8373, ISO 9283). Unfortunately, no such regulation is established yet for surgical robots. In medicine, a common way to estimate the performance of a new device is to carry out a small clinical study. Most commercially available laparoscope positioners (e.g. AESOP, EndoAssist and its successor FreeHand, LapMan, and ViKY) were introduced by means of such studies. Most authors report that these devices can actually replace the assistant, with several advantages over manual holding: more stable image

C(16)-methyl corticosteroids are far less allergenic than the non-methylated molecules.

C(16)-methyl substitution, interfering with protein binding, and halogenation, seem to reduce the allergenicity of corticosteroid molecules. Hence, when indicated, C(16)-methylated corticosteroids should be preferentially prescribed

Quantification of four Isoflavones in Forages with UPLC®-MS/MS, using the Box-Behnken Experimental Design to Optimize Sample Preparation

peer reviewedA performant method for the simultaneous quantification of daidzein, genistein, formononetin and biochanin A in forages using an UPLC®-MS/MS was developed and fully validated. The ultrasound-assisted extraction and enzymatic hydrolysis used in the sample preparation step were optimized using the Box-Behnken experimental design. The optimal extraction conditions used for a representative mix of forage plants were 80°C, 10 min and 55% methanol, and for hydrolysis they were 20°C, 18 h and pH=6. The chromatographic separation was achieved using an Acquity® UPLC® HSS T3 column, with a water/methanol linear gradient containing 0.01% of formic acid at a 0.55 mL min-1 flow rate. The four isoflavones were detected by ESI mass spectrometry in positive ion MRM mode. The method allows high throughput analyses of samples and showed an adequate linear regression model for all isoflavones over a range from 5 to 125 ng mL-1. There was good intra- and inter-day precision (≤ 8.2% and ≤ 7.6%) and accuracy (≤ 11.4% and ≤ 7.1%). The recovery rates were in an acceptable range of 70-120%, except for biochanin A, where the rate was about 50%. Good method repeatability was also observed, and there was no matrix effect or carry-over problem. The sample extracts were stable for at least 6 days of storage at -21°C and 6°C. The method proved to be sensitive, precise and accurate for discriminating a wide variety of forages likely to be grazed by ruminants according to their isoflavone content and to observe the impact storage process on isoflavone content in forages.PhytoHealt

Experimental comparison of kinematics and control interfaces for laparoscope positioners

Ergonomics is known to be poor during laparoscopic surgery because of the minimal access and the manual handling of the laparoscope, which is required to display intra-abdominal images on monitors in the absence of direct vision. Several robots were developed over the last two decades to hold and move the laparoscope, so as to offer better image stability and free the assistant’s hands and mind. The purpose of this study is to compare the motion performance of these devices, including the EVOLAP robot designed at UCL, and to assess the influence of two main factors on motion duration: the kinematic architecture and the control capabilities of the human-robot interface (i.e. the number of directions). An experimental bench was set up using a modified version of the EVOLAP robot, capable of generating laparoscope motions identical to the ones induced by the three most common kinematics among existing laparoscope positioners. Results show that the kinematics has a large influence on motion duration. It also appears that performance is increased significantly with a control interface that provides more motion directions that the commercially available ones

Performance assessment of kinematics and control interfaces for laparoscope positioners

Which laparoscope positioner is the most efficient? Simple question but still no accurate answer, nearly twenty years after the introduction of AESOP, the first robot that could hold and move the endoscope and camera used in minimally invasive laparoscopic surgery. Metrics and methodologies to measure the performance of industrial robots are defined by international standards (e.g. ISO 8373, ISO 9283). Unfortunately, no such regulation is established yet for surgical robots