In-vivo measurement of the human soft tissues constitutive laws. Applications to Computer Aided Surgery

In the 80's, biomechanicians were asked to work on Computer Aided Surgery applications since orthopaedic surgeons were looking for numerical tools able to predict risks of fractures. More recently, biomechanicians started to address soft tissues arguing that most of the human body is made of such tissues that can move as well as deform during surgical gestures [1]. An intra-operative use of a continuous Finite Element (FE) Model of a given tissue mainly faces two problems: (1) the numerical simulations have to be "interactive", i.e. sufficiently fast to provide results during surgery (which can be a strong issue in the context of hyperelastic models for example) and (2) during the intervention, the surgeon needs a device that can be used to provide to the model an estimation of the patient-specific constitutive behaviour of the soft tissues. This work proposes an answer to the second point, with the design of a new aspiration device aiming at characterizing the in vivo constitutive laws of human soft tissues. The device was defined in order to permit sterilization as well an easy intra-operative use

Electron emission at very low electron impact energy: experimental and Monte-Carlo results

The behaviour of electron emission under electron impact at very low energy is of great importance in many applications such as high energy physics, satellites, nuclear reactors, etc. However the question of the total electron reflectivity is still in discussion. Our experimental and theoretical studies show that the total reflectivity at very low energy is far from being an obvious fact. Moreover, our results show that the yield is close to zero and not equal to one for low energy incident electron.Comment: 3 pages, contribution to the Joint INFN-CERN-EuCARD-AccNet Workshop on Electron-Cloud Effects: ECLOUD'12; 5-9 Jun 2012, La Biodola, Isola d'Elba, Italy; CERN Yellow Report CERN-2013-002, pp.137-13

A weakly-supervised approach for discovering common objects in airport video surveillance footage

Object detection in video is a relevant task in computer vision. Standard and current detectors are typically trained in a strongly supervised way, what requires a huge amount of labelled data. In contrast, in this paper we focus on object discovery in video sequences by using sets of unlabelled data. Thus, we present an approach based on the use of two region proposal algorithms (a pretrained Region Proposal Network and an Optical Flow Proposal) to produce regions of interest that will be grouped using a clustering algorithm. Therefore, our system does not require the collaboration of a human except for assigning human understandable labels to the discovered clusters. We evaluate our approach in a set of videos recorded at the outdoor area of an airport where the aeroplanes park to load passengers and luggage (apron area). Our experimental results suggest that the use of an unsupervised approach is valid for automatic object discovery in video sequences, obtaining a CorLoc of 86.8 and a mAP of 0.374 compared to a CorLoc of 70.4 and mAP of 0.683 achieved by a supervised Faster R-CNN trained and tested on the same dataset.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Hardy Bacterium Isolated From Two Geographically Distinct Spacecraft Assembly Cleanroom Facilities

Earlier studies have confirmed that a tenacious hardy bacterial population manages to persist and survive throughout a spacecraft assembly process. The widespread detection of these organisms underscores the challenges in eliminating them completely. Only comprehensive and repetitive microbial diversity studies of geographically distinct cleanroom facilities will bolster the understanding of planetary protection relevant microbes. Extensive characterizations of the physiological traits demonstrated by cleanroom microbes will aid NASA in gauging the forward contamination risk that hardy bacteria (such as Tersicoccus phoenicis) pose to spacecraft. This study reports on the isolation and identification of two gram-positive, non-motile, non-spore-forming bacterial strains from the spacecraft assembly facilities at Kennedy Space Center, Florida, USA and Centre Spatial Guyanais, Kourou, French Guiana. DNA-DNA relatedness values between the novel strains indicates that these novel strains were indeed members of a same species. Phylogenetic evidence derived from a 16S ribosomal DNA analysis indicated that both the novel strains are less closely related to all other Arthrobacter species

Haptic guidance improves the visuo-manual tracking of trajectories

BACKGROUND: Learning to perform new movements is usually achieved by following visual demonstrations. Haptic guidance by a force feedback device is a recent and original technology which provides additional proprioceptive cues during visuo-motor learning tasks. The effects of two types of haptic guidances-control in position (HGP) or in force (HGF)-on visuo-manual tracking ("following") of trajectories are still under debate. METHODOLOGY/PRINCIPALS FINDINGS: Three training techniques of haptic guidance (HGP, HGF or control condition, NHG, without haptic guidance) were evaluated in two experiments. Movements produced by adults were assessed in terms of shapes (dynamic time warping) and kinematics criteria (number of velocity peaks and mean velocity) before and after the training sessions. CONCLUSION/SIGNIFICANCE: These results show that the addition of haptic information, probably encoded in force coordinates, play a crucial role on the visuo-manual tracking of new trajectories

Fluidised-bed incineration bottom ash as the sole precursor of alkali-activated binders: A comparison with bottom ash from grate incinerators

The novel formulation of alkali-activated binders (AABs) using incineration bottom ash (IBA) from fluidised bed (FB) combustion technology as a sole precursor was assessed. In addition, IBA-FB was compared with IBA from moving grate (IBA-MG) combustion technology. The AABs formulated with IBA-FB (AAB-FB) and IBA-MG (AAB-MG) were also evaluated from a physicochemical, mechanical, and environmental perspective. The results revealed that specific surface area in IBA-FB hinders the retention of kneading water of fresh pastes, affecting the workability, consistency, porosity, and mechanical strength of AAB-FB. Moreover, the low calcium content of IBA-FB requires that the formulated AABs must be cured at higher curing temperatures to ensure the formation of (N,C) ASH gels, while the high calcium content of IBA-MG promotes the formation of CSH gels at room temperature. The compressive strength results demonstrated that AAB-MG (≈ 11 MPa) and AAB-FB (≈ 8 MPa) could be used for non-structural purposes

Probing material nonlinearity at various depths by time reversal mirrors

International audienceIn this letter, the time reversal mirror is used to focus elastic energy at a prescribed location and to analyze the amplitude dependence of the focus signal, thus providing the nonlinearity of the medium. By varying the frequency content of the focused waveforms, the technique can be used to probe the surface, by penetrating to a depth defined by the wavelength of the focused waves. The validity of this concept is shown in the presence of gradual and distributed damage in concrete by comparing actual results with a reference nonlinear measurement and X ray tomography images