On the feasibility of defect detection in composite material based on thermal periodic excitation

International audienceImplementation of periodic thermal excitation to identify thermal properties (conductivity, heat capacity, diffusivity) of complex composite materials at different investigation scales (from micrometer to millimetre) presents many advantages. These methods are usually based on the thermal waves phase lag observation compared to a reference signal. In fact, phase lag evolution versus distance to the heating source or versus excitation frequency is quite informative about numerous material characteristics. For example, considering that a structural defect can modify heat propagation inside a material, diagnosis can be performed from phase lag observations and comparisons between samples with and without defects. Numerous studies have been performed considering global heating (a quite large surface of the investigated composite material is heated and defect depth or size can be detected). The proposed approach is original since periodic heating is local and aims to detect defects in the periphery of the excitation. Based on a mathematical model for thermal waves propagations and introducing complex temperature for numerical resolution (finite element method), a feasibility study has allowed a sensitivity analysis. This preliminary study also provides information on the operating protocol, for heating(frequency, power, size of the source), and observation (transmission or reflection). Then, experimental device and early experimental results are briefly exposed

Territoires : composition et plasticité

Est-il possible d'exprimer la plasticité du monde urbain par l'art, le mien mais aussi celui d'artistes contemporains ? Et a contrario d'expliquer l'art par les fonctionnements formels propres à ce monde ? Nous nous sommes ancrée sur certains points clefs qui semblaient les relier tous les deux, tels que la notion de frontière et de limite, ou encore les temps compositionnels internes, puis sur leur surface. Ainsi, notre recherche sur le cadrage nous a portée à l'acte de frontière, associant sa forme à la question d'identité. Et ce fragment identitaire, nous a conduite à la relation entre la cartographie et les formats fragmentés tels que les polyptyques ou les photomontages. Ensuite, nous avons cherché de quelle façon les compositions internes des œuvres pouvaient exprimer celles de la ville, tant par le choix scénique du mur, que par la rythmique de la composition qui met le corps en et par la nécessité d'intégration qui est indispensable à ces deux ensembles compositionnels. Pour finir, nous avons établi des relations entre la surface de la ville ombre et lumière, et la surface picturale, nous amenant à redéfinir les questions de profondeur, mettant en avant qu'il s'établit alors un échange entre cette matière active qui tend à un devenir homme et l'homme à un devenir objet

Thermographie infrarouge synchronisée avec la mesure de paramètres météorologiques : Application à l'auscultation du tablier d'un pont ouvert au trafic

International audienceCet article présente un monitoring thermique conduit pendant plusieurs jours sur le tablier du pont de « Musmeci » à Potenza (Italie). L’analyse des données est conduite en exploitant la mesure de paramètres météorologiques synchronisée avec l’acquisition d’images thermiques. Une analyse par FFT, permet de détecter sur les séquences de cartes d’amplitude et de phase la structure interne du tablier. Un modèle thermique exprimé dans le domaine fréquentiel a été développé et couplé à une procédure d’estimation de paramètres.Une cartographie de la distribution spatiale de la conductivité thermique apparente est ainsi calculée puis comparée avec l’analyse d’images par approche fréquentielle

Study of an optimal heating duration indicator for square pulsed thermography applied to CFRP gluing quality control

International audienceDuring previous works, square pulsed thermography was used to carry out non destructive testing of bonding quality of CFRP glued on civil engineering structures during reinforcement operations [1,2]. The use of such wave form excitation was motivated by " on-site " requirements, but also by measurements duration, number of composite layers to test, depth of possible faulting areas versus temperature elevation allowed at composite level according to inner heat diffusion. Nevertheless, square pulsed excitation implies to choose an adapted heat duration. This duration is directly linked to the reliability of the parameter estimator [3]. In fact, after a certain duration the standard deviation of the estimation procedure stagnates. According to these observations, an indicator able to predict the sufficient heating time when the reliability of the parameter estimator reached an asymptotic evolution behavior was studied. Based on the absolute thermal contrast, the proposed indicator Iph is defined with the maximum thermal contrast ∆Tmax and the time delay (tph) between the heating time tc and the appearance of the maximum contrast, as shown in figure 1 (left). A typical evolution of the Iph indicator is proposed in figure 1 (right). This indicator allows to take into acount the detectability as well as the induced flaw temporal effect on the thermal contrast shape evolution. It has been observed that the maximum of Iph is connected with the sufficient heating time when the standard deviation of the estimation procedure tends to be minimized. This paper will present the establishment of this indicator for optimal square heating time and present an analysis of results obtained with numerical simulations and laboratory experiments. Figure 1 Absolute thermal contrast characteristics (left) and indicator Iph evolution with heating time duration References [1] A. Crinière, J. Dumoulin, C. Ibarra-Castanedo and X. Maldague , " Inverse model for defect characterization of externally glued CFRP on reinforced concrete structures: Comparative study of square pulsed and pulsed thermography " ,] L-D. Théroux, J. Dumoulin and X. Maldague , " Square heating applied to shearography and active infrared thermography measurements coupling: from feasibility test in laboratory to numerical study of pultruded CFRP plates glued on concrete specimen " ,Strain journal, Wiley editor, 2014. doi:10.1111/str.12086. [3] V. Feuillet, L. Ibos, M. Fois, J. Dumoulin, Y. Candau, " Defect detection and characterization in composite materials using Square Pulse Thermography coupled with Singular Value Decomposition analysis and thermal quadrupole modeling " , NDT&E International, Volume 51, Octobre 2012, pp 58–67, Elsevier, http://dx

Structural basis for HCMV Pentamer receptor recognition and antibody neutralization

Human cytomegalovirus (HCMV) represents the viral leading cause of congenital birth defects and uses the gH/ gL/UL128-130-131A complex (Pentamer) to enter different cell types, including epithelial and endothelial cells. Upon infection, Pentamer elicits the most potent neutralizing response against HCMV, representing a key vaccine candidate. Despite its relevance, the structural basis for Pentamer receptor recognition and antibody neutralization is largely unknown. Here, we determine the structures of Pentamer bound to neuropilin 2 (NRP2) and a set of potent neutralizing antibodies against HCMV. Moreover, we identify thrombomodulin (THBD) as a functional HCMV receptor and determine the structures of the Pentamer-THBD complex. Unexpectedly, both NRP2 and THBD also promote dimerization of Pentamer. Our results provide a framework for understanding HCMV receptor engagement, cell entry, antibody neutralization, and outline strategies for antiviral therapies against HCMV

RNA and DNA Bacteriophages as Molecular Diagnosis Controls in Clinical Virology: A Comprehensive Study of More than 45,000 Routine PCR Tests

Real-time PCR techniques are now commonly used for the detection of viral genomes in various human specimens and require for validation both external and internal controls (ECs and ICs). In particular, ICs added to clinical samples are necessary to monitor the extraction, reverse transcription, and amplification steps in order to detect false-negative results resulting from PCR-inhibition or errors in the technical procedure. Here, we performed a large scale evaluation of the use of bacteriophages as ICs in routine molecular diagnosis. This allowed to propose simple standardized procedures (i) to design specific ECs for both DNA and RNA viruses and (ii) to use T4 (DNA) or MS2 (RNA) phages as ICs in routine diagnosis. Various technical formats for using phages as ICs were optimised and validated. Subsequently, T4 and MS2 ICs were evaluated in routine real-time PCR or RT-PCR virological diagnostic tests, using a series of 8,950 clinical samples (representing 36 distinct specimen types) sent to our laboratory for the detection of a variety of DNA and RNA viruses. The frequency of inefficient detection of ICs was analyzed according to the nature of the sample. Inhibitors of enzymatic reactions were detected at high frequency in specific sample types such as heparinized blood and bone marrow (>70%), broncho-alveolar liquid (41%) and stools (36%). The use of T4 and MS2 phages as ICs proved to be cost-effective, flexible and adaptable to various technical procedures of real-time PCR detection in virology. It represents a valuable strategy for enhancing the quality of routine molecular diagnosis in laboratories that use in-house designed diagnostic systems, which can conveniently be associated to the use of specific synthetic ECs. The high rate of inhibitors observed in a variety of specimen types should stimulate the elaboration of improved technical protocols for the extraction and amplification of nucleic acids

Spindle Assembly Checkpoint Protein Dynamics Reveal Conserved and Unsuspected Roles in Plant Cell Division

Background: In eukaryotes, the spindle assembly checkpoint (SAC) ensures that chromosomes undergoing mitosis do not segregate until they are properly attached to the microtubules of the spindle. Methodology/Principal Findings: We investigated the mechanism underlying this surveillance mechanism in plants, by characterising the orthogolous SAC proteins BUBR1, BUB3 and MAD2 from Arabidopsis. We showed that the cell cycle-regulated BUBR1, BUB3.1 and MAD2 proteins interacted physically with each other. Furthermore, BUBR1 and MAD2 interacted specifically at chromocenters. Following SAC activation by global defects in spindle assembly, these three interacting partners localised to unattached kinetochores. In addition, in cases of 'wait anaphase', plant SAC proteins were associated with both kinetochores and kinetochore microtubules. Unexpectedly, BUB3.1 was also found in the phragmoplast midline during the final step of cell division in plants. Conclusions/Significance: We conclude that plant BUBR1, BUB3.1 and MAD2 proteins may have the SAC protein functions conserved from yeast to humans. The association of BUB3.1 with both unattached kinetochore and phragmoplast suggests that in plant, BUB3.1 may have other roles beyond the spindle assembly checkpoint itself. Finally, this study of the SAC dynamics pinpoints uncharacterised roles of this surveillance mechanism in plant cell division

Revolutionizing Clinical Microbiology Laboratory Organization in Hospitals with In Situ Point-of-Care

BACKGROUND: Clinical microbiology may direct decisions regarding hospitalization, isolation and anti-infective therapy, but it is not effective at the time of early care. Point-of-care (POC) tests have been developed for this purpose. METHODS AND FINDINGS: One pilot POC-lab was located close to the core laboratory and emergency ward to test the proof of concept. A second POC-lab was located inside the emergency ward of a distant hospital without a microbiology laboratory. Twenty-three molecular and immuno-detection tests, which were technically undemanding, were progressively implemented, with results obtained in less than four hours. From 2008 to 2010, 51,179 tests yielded 6,244 diagnoses. The second POC-lab detected contagious pathogens in 982 patients who benefited from targeted isolation measures, including those undertaken during the influenza outbreak. POC tests prevented unnecessary treatment of patients with non-streptococcal tonsillitis (n = 1,844) and pregnant women negative for Streptococcus agalactiae carriage (n = 763). The cerebrospinal fluid culture remained sterile in 50% of the 49 patients with bacterial meningitis, therefore antibiotic treatment was guided by the molecular tests performed in the POC-labs. With regard to enterovirus meningitis, the mean length-of-stay of infected patients over 15 years old significantly decreased from 2008 to 2010 compared with 2005 when the POC was not in place (1.43±1.09 versus 2.91±2.31 days; p = 0.0009). Altogether, patients who received POC tests were immediately discharged nearly thrice as often as patients who underwent a conventional diagnostic procedure. CONCLUSIONS: The on-site POC-lab met physicians' needs and influenced the management of 8% of the patients that presented to emergency wards. This strategy might represent a major evolution of decision-making regarding the management of infectious diseases and patient care