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International audience; Thermal treatments can be considered as an accelerated ageing, bringing partly similar changes in properties as naturally aged wood. Thermal treatment was applied on white mulberry (Morus alba L.), a dominant species for making musical instruments from middle-East to Far-East, to investigate the effects on the vibro-mechanical and physical properties of this wood, and the results compared to previously published data on spruce (Picea abies Karst.) as a reference for the soundboard of Western string instruments. Thermal treatment (TT) at 150 °C and 0% of relative humidity was applied to five analogous groups of specimens with five different durations (2.5, 8, 24, 72, 261 hours). Humidity reconditioning of specimens was done to explore the reversibility of TT effects. Physical and vibrational properties such as specific gravity (γ), equilibrium moisture content (EMC), CIELab colorimetric values, specific modulus of elasticity (E'/γ) and damping coefficient (tanδ) in longitudinal (L) and radial (R) directions, have been measured after stabilisation of samples in standard conditions (20 °C, 65% RH), before and after TT and then after reconditioning. Untreated mulberry had a low EMC, very low L/R anisotropy and low E'L/γ, and relatively low tanδ. Weight loss (WL) and CIELab values evolved similarly during TT for mulberry and for previous results on spruce, however, their EMC and vibrational properties were affected differently. This could be explained in part by the low anisotropy of mulberry, and in part by its particular extractives. The parts of irreversible effects, linked to chemical modification or degradation, and of reversible effects, linked to physical configuration, were different between mulberry and spruce. The applied treatments did not bring permanent "improvements" in vibrational properties of mulberry, yet its colour appearance was enhanced.

Lung cancer is the most common cause of cancer related death in both men and women. Radiation therapy is widely used for lung cancer treatment. However, this method can be challenging due to respiratory motion. Motion modeling is a popular method for respiratory motion compensation, while biomechanics-based motion models are believed to be more robust and accurate as they are based on the physics of motion. In this study, we aim to develop a biomechanics-based lung tumor tracking algorithm which can be used during External Beam Radiation Therapy (EBRT). An accelerated lung biomechanical model can be used during EBRT only if its boundary conditions (BCs) are defined in a way that they can be updated in real-time. As such, we have developed a lung finite element (FE) model in conjunction with a Neural Networks (NNs) based method for predicting the BCs of the lung model from chest surface motion data. To develop the lung FE model for tumor motion prediction, thoracic 4D CT images of lung cancer patients were processed to capture the lung and diaphragm geometry, trans-pulmonary pressure, and diaphragm motion. Next, the chest surface motion was obtained through tracking the motion of the ribcage in 4D CT images. This was performed to simulate surface motion data that can be acquired using optical tracking systems. Finally, two feedforward NNs were developed, one for estimating the trans-pulmonary pressure and another for estimating the diaphragm motion from chest surface motion data. The algorithm development consists of four steps of: 1) Automatic segmentation of the lungs and diaphragm, 2) diaphragm motion modelling using Principal Component Analysis (PCA), 3) Developing the lung FE model, and 4) Using two NNs to estimate the trans-pulmonary pressure values and diaphragm motion from chest surface motion data. The results indicate that the Dice similarity coefficient between actual and simulated tumor volumes ranges from 0.76±0.04 to 0.91±0.01, which is favorable. As such, real-time lung tumor tracking during EBRT using the proposed algorithm is feasible. Hence, further clinical studies involving lung cancer patients to assess the algorithm performance are justified.

International audience; The influence of vanishing process on the vibrational properties of the wood+coating systems was studied using different types and recipes of instrument making varnishes, used in traditional Iranian string instruments making, or in European violin-quartet making. The focus is on the time evolution of these properties, that can be involved in the changing behaviour of newly made instruments. The different tested varnishes recipes were applied on wood representative of each culture, studied both along-the-grain and cross-grain, and monitored through time for up to more than one year. The different effects, both immediate and their kinetics through time after application, are discussed.

Wood is commonly used for making musical instruments. During the process it is often subjected to treatments, that either modify its volume or its surface properties. Two species used for for string instruments were studied, representative of different cultures: Spruce (Picea abies Karst.) used in Europe and White Mulberry (Morus alba L.) used in Iran. For each of them the effect of thermal treatment at moderate temperature (

International audience

International audience; Mild thermal treatments (below 160°C) are increasingly considered as a mean to accelerate some beneficial effects of wood ageing. In this work, treatments were done in a pressurized reactor which has controlled conditions of temperature and relative humidity. We performed 5 treatments, each one applied to poplar (for study of dimensional stability in view of panel paintings applications) and to spruce (for study of axial and radial acoustic properties in view of musical applications). Three groups were treated at 150°C with, respectively, 0% (constant) relative humidity (RH), 25% constant RH, and cyclic variations between these 2 RH. The same protocol was applied to three other groups at a temperature of 130°C. The oven-dry weight, dimensions and colorimetric properties and the air-dry (3 weeks at 20°C and 65% RH) weight, dimensions and viscoelastic vibrational properties were measured before and after treatment. Intermediate data were also measured in the course of the treatments for weight, dimensions and colorimetric properties, in order to model the kinetics of modification. Although oven-dry weight loss were moderate (maximum 4%) in these relatively mild conditions, properties were significantly improved. Moisture sorption and swelling/shrinkage were significantly reduced, as well as vibration damping, without negative effects of the rigidity. The effect of reconditioning at high relative humidity was also investigated.

ISBN 978-961-6144-37-7; International audience; A mild hygro-thermal treatment was applied to wood, as a first step of pre-treatment/coating systems for musical instrument making. Longitudinal (L=150 x R=12 x T=2.5 mm) and radial Spruce specimens (R=150 x L=12 x T=2.5 mm) were trated in reactors maintained at a temperature of 130 or 150°C, and a relative humidity (RH) of 0% or varying between 0% and 25%. Weight loss (WL), equilibrium moisture content (EMC), density (p) and vibrational properties in bending (E/p, tand), were measured before and after treatment, while colour parameters were recorded also at intermediate steps.