New data-driven method from 3D confocal microscopy for calculating phytoplankton cell biovolume.

Confocal laser scanner microscopy coupled with an image analysis system was used to directly determine the shape and calculate the biovolume of phytoplankton organisms by constructing 3D models of cells. The study was performed on Biceratium furca (Ehrenberg) Vanhoeffen, which is one of the most complex-shaped phytoplankton. Traditionally, biovolume is obtained from a standardized set of geometric models based on linear dimensions measured by light microscopy. However, especially in the case of complex-shaped cells, biovolume is affected by very large errors associated with the numerous manual measurements that this entails. We evaluate the accuracy of these traditional methods by comparing the results obtained using geometric models with direct biovolume measurement by image analysis. Our results show cell biovolume measurement based on decomposition into simple geometrical shapes can be highly inaccurate. Although we assume that the most accurate cell shape is obtained by 3D direct biovolume measurement, which is based on voxel counting, the intrinsic uncertainty of this method is explored and assessed. Finally, we implement a data-driven formula-based approach to the calculation of biovolume of this complex-shaped organism. On one hand, the model is obtained from 3D direct calculation. On the other hand, it is based on just two linear dimensions which can easily be measured by hand. This approach has already been used for investigating the complexities of morphology and for determining the 3D structure of cells. It could also represent a novel way to generalize scaling laws for biovolume calculation.

Few layered MoS2 lithography with an AFM tip: description of the technique and nanospectroscopy investigations.

A novel technique to lithograph the MoS2 surface is described here. Mechanically exfoliated MoS2 flakes have been patterned with an atomic force microscope tip. After the patterning process, the lithographed areas have been removed by selective chemical etching. The electronic properties of the MoS2 flakes have been analyzed with spatially resolved photoelectron spectroscopy, with tunable incident photon energy, provided by a synchrotron light source. Tens of meV core level shifts can be recorded in relation to the flakes edges, coming from both the exfoliation and from the lithography.

[The treatment of infected pseudarthrosis of the tibia using Umiarov's technic (epiderm-fascio-osteoplasty)]. / Le traitement des pseudarthroses infectées du tibia selon la technique d'Umiarov (epidermo-fascio-ostéoplastie).

Infected tibial nonunions, with bone loss and extensive soft tissue damage, often require long multistage treatment. Epidermo-fascial osteoplasty according to Umiarov allows the removal of important bone loss without previous sterilization of purulent foci or coverage of the soft tissues. The results obtained in 5 cases treated by Umiarov technique are very satisfactory and allow to consider this method as a valid alternative to the traditional treatments.

Primitive synovial chondromatosis of the hip joint.

Primitive synovial chondromatosis of the hip is quite rare. Through the presentation of four new cases, the authors discuss the pathologic and clinical features of this disease and evaluate the performance of imaging studies, emphasizing the value of CT scan for confirmation of radiographic findings. The indication for surgical treatment is analyzed for each stage of the disease.

The statics of cervical traction.

The statics of a sliding body was used to study the distribution of forces during the application of cervical traction in supine patients. This theoretical analysis was completed using a dynamometer to determine the static friction between bed surface and patient head. Therefore, we measured the head weight in 12 inpatients and the minimum force that causes impending motion of the head on the bed surface. The static friction coefficient was calculated from the ratio of the two quantities. The forces acting on the cervical spine were determined by inserting the former data into a specifically designed algorithm that forecasted a progressively increasing traction angle. The coefficient of static friction was 0.62, whereas the maximum available force acting on the cervical spine was obtained with a 35 degrees traction inclination. In contrast, the forces dissipated by the plane progressively decreased with larger angles.