A theoretical analysis of the electromagnetic environment of the AS330 super Puma helicopter external and internal coupling

Numerical techniques such as Finite Difference Time Domain (FDTD) computer programs, which were first developed to analyze the external electromagnetic environment of an aircraft during a wave illumination, a lightning event, or any kind of current injection, are now very powerful investigative tools. The program called GORFF-VE, was extended to compute the inner electromagnetic fields that are generated by the penetration of the outer fields through large apertures made in the all metallic body. Then, the internal fields can drive the electrical response of a cable network. The coupling between the inside and the outside of the helicopter is implemented using Huygen's principle. Moreover, the spectacular increase of computer resources, as calculations speed and memory capacity, allows the modellization structures as complex as these of helicopters with accuracy. This numerical model was exploited, first, to analyze the electromagnetic environment of an in-flight helicopter for several injection configurations, and second, to design a coaxial return path to simulate the lightning aircraft interaction with a strong current injection. The E field and current mappings are the result of these calculations

Constraints on Recoil Leader Properties Estimated from X-ray Emissions in Aircraft-Triggered Discharges

During Airbus aircraft campaigns flying into thunderstorms in 2014–2016, X-rays were observed during two stages of aircraft-triggered lightning: nanosecond pulses of X-rays associated with negative leader steps and bursts of X-rays during recoil events. This work will focus on the observations of X-ray bursts associated with recoils. Recoils are observed as microsecond-fast changes in the local electric field, associated with large currents passing through the aircraft, and are found to sometimes be associated with bursts of X-rays. From over 200 aircraft-triggered lightning strikes, 54 recoil events were found to be associated with microsecond bursts of X-rays. The majority of the bursts consist of 1–3 X-ray pulses, with some bursts containing as many as 29 X-ray pulses. We compare the observed superposed X-ray spectrum with modeled spectra using a GEANT4 model of the detector and aircraft, to determine the source potential needed to accelerate the electrons that produce the observed X-rays. A model of the recoil leader was made to determine the gap distance and gap potential between the recoil leader and the aircraft. From the modeling, we determine a solution space for the gap and leader lengths where the gap length is constrained by the observed minimum and maximum times between the onset of the X-ray pulses and the onset of the current pulses detected at the aircraft (1 to 93 m). We also find two constraints from the fitting of the modeled spectra to the superposed spectrum, limiting the leader length to between 1 and ∼240 m.publishedVersio

In‐Flight Observation of Positron Annihilation by ILDAS

We report a 511‐keV photon flux enhancement that was observed inside a thundercloud and is a result of positron annihilation. The observation was made with the In‐flight Lightning Damage Assessment System (ILDAS) on board of an A340 test aircraft. The aircraft was intentionally flying through a thunderstorm at 12‐km altitude over Northern Australia in January 2016. Two gamma ray detectors showed a significant count rate increase synchronously with fast electromagnetic field variations registered by an on‐board antenna. A sequence of 10 gamma ray enhancements was detected, each lasted for about 1 s. Their spectrum mainly consists of 511‐keV photons and their Compton component. The local electric activity during the emission was identified as a series of static discharges of the aircraft. A full‐scale Geant4 model of the aircraft was created to estimate the emission area. Monte Carlo simulation indicated that the positrons annihilated in direct vicinity or in the aircraft body.publishedVersio

Estimation of the load produced by the electro-thermal behaviour of lightning strike protection layers on a composite panel

The lightning damage mechanism for carbon laminate aeronautical structure is a complex multi-physical phenomenon. The lightning current entering into the surface metallic protection, called LSP (Lightning Strike Protection) and the carbon plies generates Joule’s effects and magnetic forces which both induce mechanical forces and surface explosion that has a significant mechanical impact. In this paper, the focus is made on the contribution of the surface explosion. An electro-thermal model of the vaporization profile has been first validated with lightning test results for an accurate dynamic profile. In a second step an overpressure profile combined with the vaporization front has been implemented in a mechanical model. The deflection profiles of the mechanical model are in good correlation with measurements. The contribution of the explosion is the major contributor in the loading of composite panel. A next step will consist in the determination of the contribution of the CFRP (Carbon Fiber Reinforced Plastic) explosion in the first plies which initiates the damage in the composite by breaking the fibers

Lightning damage assessment into composite based on surface explosion and fiber breakage

Lightning damage mechanism for composite aircraft structure is a complex multi-physical phenomenon. The lightning current entering into the surface metallic protection and the carbon plies generates Joule’s effects and electromagnetic forces which both induce mechanical forces and surface explosion that produce a significant mechanical impact. The explosion of the lightning strike protection has been recorded through the measurement of the vaporization profile evolution in space and time using transparent glass epoxy substrates. In this paper, this profile is combined to shock wave model developed by the study of electric explosion on wire equivalent to web of ECF. The second important phenomenon is fiber breakage due to current flow in CFRP. This has been assessed through specific lightning test measuring the current distribution between CFRP and LSP depending on the paint thickness. It is aimed is this paper to present the tests setup and observations. Those two loading components have been injected into a mechanical model using Abaqus Explicit® in order to assess the damage ignition and propagation in the composite thickness as a function of time. Simulations are similar to previous studies but use real tests measurements for the pressure evolution instead of an impulsion induced estimation. Results of the simulations are confronted with laboratory lightning tests. Deflection as functions of time has been measured thanks to stereo correlation devices. Simulated damage distributions are compared to post-mortem non-destructive and destructive measurement in the core of the composite plates

Identification of novel TMPRSS2:ERG mechanisms in prostate cancer metastasis: involvement of MMP9 and PLXNA2

International audienceProstate cancer (PCa) is one of the major public health problems in Western countries. Recently, the TMPRSS2:ERG gene fusion, which results in the aberrant expression of the transcription factor ERG, has been shown to be the most common gene rearrangement in PCa. Previous studies have determined the contributions of this fusion in PCa disease initiation and/or progression in vitro and in vivo. In this study on TMPRSS2:ERG regulation in PCa, we used an androgen receptor and TMPRSS2:ERG fusion double-negative PCa cell model: PC3c. In three cell clones with different TMPRSS2:ERG expression levels, ectopic expression of the fusion resulted in significant induction of cell migration and invasion in a dose-dependent manner. In agreement with this phenotype, high-throughput microarray analysis revealed that a set of genes, functionally associated with cell motility and invasiveness, were deregulated in a dose-dependent manner in TMPRSS2:ERG-expressing cells. Importantly, we identified increased MMP9 (Metalloproteinase 9) and PLXNA2 (Plexin A2) expression in TMPRSS2:ERG-positive PCa samples, and their expression levels were significantly correlated with ERG expression in a PCa cohort. In line with these findings, there was evidence that TMPRSS2:ERG directly and positively regulates MMP9 and PLXNA2 expression in PC3c cells. Moreover, PLXNA2 upregulation contributed to TMPRSS2:ERG-mediated enhancements of PC3c cell migration and invasion. Furthermore, and importantly, PLXNA2 expression was upregulated in metastatic PCa tumors compared with localized primary PCa tumors. This study provides novel insights into the role of the TMPRSS2:ERG fusion in PCa metastasis

Re-examining Paul Broca’s initial presentation of M. Leborgne: understanding the impetus for brain and language research

The 150th anniversary affords an opportunity to revisit the circumstances surrounding Paul Broca’s case report celebrated today as the moment of discovery of aphasia. The proceedings from January to June 1861 of the Paris Society of Anthropology are examined to reconstruct the events surrounding the report of M. Leborgne on April 18th. From a close reading of the presentations and discussions which took place during this period it is apparent that Broca’s case report was a minor diversion to a debate about cranial measurements and their relation to intelligence in individuals and racial groups. Moreover, it appears that little attention was granted to Broca’s first case at the time. While his ideas about localization and specialization developed and change over the next decade, it represented a minor field of interest for him. Nevertheless Broca’s work on aphasia inspired research throughout Europe and North America and went on to have a lasting impact on both aphasiology and neuropsychology

The Brain and the Behavioral Sciences

The increasing visibility and sense of intellectual opportunity associated with neuroscience in recent years have in turn stimulated a growing interest in its past. For the first time, a general reference book on the history of science has seen fit to include a review of the history of the brain and behavioral sciences as a thread to be reckoned with within the broader narrative tapestry. On the one hand, this looks like a welcome sign that a new historical subfield has “come of age.” On the other hand, when one settles down to the task of composing a “state of the art” narrative, one realizes just how much these are still early days. The bulk of available secondary literature still swims in a space between nostalgic narratives of great men and moments, big “march of ideas” overviews, and an unsystematic patchwork of more theorized forays by professional historians into specific themes (e.g., phrenology, brain localization, reflex theory). The challenge of imagining a comprehensive narrative is made all the more formidable by the fact that we are dealing here with a history that resists any easy or clean containment within disciplinary confines. The paper trail of ideas, experiments, clinical innovations, institutional networks, and high-stakes social debates not only moves across obvious sites of activity such as neurology, neurosurgery, and neurophysiology but also traverses fields as (only apparently) distinct as medicine, evolution, social theory, psychology, asylum management, genetics, philosophy, linguistics, anthropology, computer science, and theology.History of Scienc