CONSERT suggests a change in local properties of 67P/Churyumov-Gerasimenko's nucleus at depth

International audienceAfter the successful landing of Philae on the nucleus of 67P/Churyumov-Gerasimenko, the Rosetta mission provided the first opportunity of performing measurements with the CONSERT tomographic radar in November 2014. CONSERT data were acquired during this first science sequence. They unambiguously showed that propagation through the smaller lobe of the nucleus was achieved. Aims. While the ultimate objective of the CONSERT radar is to perform the tomography of the nucleus, this paper focuses on the local characterization of the shallow subsurface in the area of Philae’s final landing site, specifically determining the possible presence of a permittivity gradient below the nucleus surface.Methods. A number of electromagnetic simulations were made with a ray-tracing code to parametrically study how the gradient of the dielectric constant in the near-subsurface affects the ability of CONSERT to receive signals.Results. At the 90 MHz frequency of CONSERT, the dielectric constant is a function of porosity, composition, and temperature. The dielectric constant values considered for the study are based on observations made by the other instruments of the Rosetta mission, which indicate a possible near-surface gradient in physical properties and on laboratory measurements made on analog samples. Conclusions. The obtained simulated data clearly show that if the dielectric constant were increasing with depth, it would have prevented the reception of signal at the CONSERT location during the first science sequence. We conclude from our simulations that the dielectric constant most probably decreases with depth

Flights Are Ten a Sail – Re-use and Commonality in the Design and System Engineering of Small Spacecraft Solar Sail Missions with Modular Hardware for Responsive and Adaptive Exploration

The exploration of small solar system bodies started with fast fly-bys of opportunity on the sidelines of missions to the planets. The tiny new worlds seen turned out to be so intriguing and different from all else(and each other) that dedicated sample-return and in-situ analysis missions were developed and launched. Through these, highly efficient low-thrust propulsion expanded from commercial use into mainstream and flagship science missions, there in combination with gravity assists. In parallel, the growth of small spacecraft solutions accelerated in numbers as well as individual spacecraft capabilities. The on-going missions OSIRIS-REx (NASA) or Hayabusa2 (JAXA) with its landers MINERVA-II and MASCOT, and the upcoming NEA scout mission are examples of this synergy of trends. The continuation of these and other related developments towards a propellant-less and highly efficient class of spacecraft for solar system exploration emerges in the form of small spacecraft solar sails designed for carefree handling and equipped with carried landers and application modules. These address the needs of all asteroid user communities– planetary science, planetary defence, and in-situ resource utilization – as well as other fields of solar system science and applications such as space weather warning and solar observations. Already the DLR-ESTEC GOSSAMER Roadmap for Solar Sailing initiated studies of missions uniquely feasible with solar sails such as Displaced L1 (DL1) space weather advance warning and monitoring and Solar Polar Orbiter(SPO) delivery, which demonstrate the capabilities of near-term solar sails to reach any kind of orbit in the inner solar system. This enables Multiple Near-Earth Asteroid (NEA) rendezvous missions (MNR),from Earth-coorbital to extremely inclined and even retrograde target orbits. For these mission types using separable payloads, design concepts can be derived from the separable Boom Sail Deployment Units characteristic of DLR GOSSAMER solar sail technology, nanolanders like MASCOT, or microlanders like the JAXA-DLR Jupiter Trojan Asteroid Lander for the OKEANOS mission which can shuttle from the sail to the targets visited and enable multiple NEA sample-return missions. These nanospacecraft scale components are an ideal match creating solar sails in micro-spacecraft format whose launch configurations are compatible with secondary payload platforms such as ESPA and ASAP. The DLR GOSSAMER solar sail technology builds on the experience gained in the development of deployable membrane structures leading up to the successful ground deployment test of a (20 m) solar sail at DLR Cologne in 1999 and in the 20 years since

Kératite herpétique et allogreffe de cornée

La kératite liée au virus herpes simplex (HSV) est la première cause de cécité infectieuse dans les pays développés. Elle peut entraîner une opacification cornéenne justifiant une greffe de cornée. L'infection herpétique peut survenir après la greffe en cas de réactivation d'un virus latent chez le receveur, mais aussi par transmisson du donneur à l'hôte, entraînant alors un échec primaire de la greffe. Dans ce travail, nous avons étudié le diagnostic pré-opératoire, le comportement du virus lors de la conservation de cornées, et l'influence de l'infection sur le pronostic de la greffe. Nous avons montré que les larmes pouvaient être infectantes pour les herpesvirus même chez les patients asymptomatiques, que les cornées de donneurs même non herpétiques pouvaient contenir de l'ADN viral, principalement associé aux kératocytes, et que la recherche d'anticorps produits localement pouvait contribuer au diagnostic de kératite herpétique. Nous avons développé deux modèles expérimentaux de conservation de cornée, qui ont montré l'effet cytopathogène de HSV in vitro sur des cornées en culture, et la réduction temps et température dépendante de la présence d'ADN viral dans les cornées infectées lors de la conservation. Enfin, l'étude de cohortes de receveurs nous a permis d'associer l'échec primaire de greffeà la présence d'ADN viral dans la cornée du donneurLIMOGES-BU Médecine pharmacie (870852108) / SudocPARIS-BIUM (751062103) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

Mésocentre Ciment : une pile logicielle pour la mutualisation

National audienceLa mutualisation est au coeur du développement du mésocentre CIMENT, elle se traduit par la mise en commun des plateformes matérielles et une homogénéisation forte des politiques d'administration. De plus, un soutien important est apporté aux développements de la pile logicielle pour l'exploitation de l'infrastructure. Ces deux approches permettent ensemble d'apporter des solutions particulièrement adaptées aux besoins des communautés d'utilisateurs en leur offrant un soutien de proximité. Parmi les logiciels mis en place pour l'exploitation de l'infrastructure du mésocentre, 3 logiciels clés sont développés ou co-developpés par les ingénieurs CIMENT

Rosetta rendezvous and CONSERT operations in 2014: A chimeric surface model of 67P/Churyumov Gerasimenko

International audienceIn 2014 the European Space Agency's Rosetta probe will rendezvous with the comet 67P/Churyumov Gerasimenko (67P) and the Philae Lander will land on the surface of the nucleus. Following the landing, the COmet Nucleus Sounding Experiment by Radiowave Transmission (CONSERT) radar will perform the tomography of the nucleus by measuring radiowave propagation through the comet between the Lander and the orbiter. Preparation for these operations, in particular the development and validation of simulation software, requires a shape model of the surface of 67P. The complexity of this model should reflect the environmental conditions that will be found in 2014. In this paper, we show that existing models of 67P are not of a sufficiently high resolution to constitute interesting test cases. Following a review of current shape models for other comets, we propose a composite which is a hybrid of the 67P and 81P/Wild 2 models

Development of a standardised human in vitro digestion protocol based on macronutrient digestion using response surface methodology.

Bioaccessibility studies should be taken into account when evaluating the physiological effects of ingested compounds at the intestine level. Several in vitro digestion protocols have been described, with a wide range of experimental conditions but no optimised protocol exists. In order to fill in this gap, we evaluated the influence of three continuous factors (pH, incubation time, and enzyme concentrations), in the range of values found in literature, on the digestion of standard macronutrients (starch, albumin, triolein) alone or in mixture. Three central composite designs, using response surface methodology, were employed to model the three abiotic steps of pre-colonic digestion. A validated in vitro digestion was eventually set up for the salivary step (pH 6.9, 5 min, 3.9 units α-amylase/ml), the gastric step (pH 2, 90 min, 71.2 units pepsin/ml), and the abiotic duodenal step (pH 7, 150 min, 9.2mg pancreatin and 55.2mg bile extract/ml)

3D Time-domain electromagnetic full waveform inversion in Debye dispersive medium accelerated by multi-GPU paralleling

International audienceElectromagnetic full waveform inversion in Debye dispersive medium (EFWI-D) is a promising technique to reconstruct the inner structure and electrical properties of the medium such as soil, rock and biological tissues. Same as conventional full waveform inversion, EFWI-D requires high computational cost, especially in the 3D case. To reduce the long computation time, we design and implement the EFWI-D algorithm in time domain using multiple GPU cards. The inversion method is based on the L-BFGS optimization algorithm, which can increase the convergence of the misfit function, while the auxiliary differential equation (ADE) method is employed for modeling the Debye dispersive medium by using exponential time differencing (ETD) finite-difference time-domain (FDTD) approach. Moreover, a multi-stream strategy is performed in the workflow to improve the computation performance. Numerical results illustrate the improvement of the computational performance and the preliminarily feasibility of the proposed inversion algorithm

Specific antibody production in herpes keratitis: intraocular inflammation and corneal neovascularisation as predicting factors

International audiencePURPOSE: The purpose of the study is to investigate whether analysis of specific antibody synthesis can aid the diagnosis of herpes keratitis. METHODS: Aqueous humor was collected from 39 patients with presumed recurrent herpes keratitis, including 23 consulting for keratitis and 16 patients scheduled for penetrating keratoplasty. Local antibody production was ascertained by analysis of paired aqueous humor/serum samples, using a modified micro-ELISA technique. RESULTS: Local production of antibodies was found in 32 patients (82%): anti-herpes simplex virus (HSV) antibodies in 26 (67%) and anti-varicella zoster virus (VZV) antibodies in 11 (28%). Twenty of 23 patients with active keratitis (87%), and 12 of 16 undergoing keratoplasty (75%), tested positive. Five patients had local production of both anti-HSV and anti-VZV antibodies, whereas seven patients tested negative. Local antibody production was significantly associated with intraocular inflammation (P<0.05), corneal neovascularisation (P<0.05), and positive response to anti-viral treatment (P<0.05). No complications were encountered in sampling aqueous humor. CONCLUSIONS: Assessment of local anti-HSV and -VZV antibody production is a safe and reliable diagnostic procedure for recurrent herpes keratitis. It might be particularly helpful in patients presenting with intraocular inflammation and neovascularisation since it discriminates between herpes and non-herpes pathologies and may therefore be useful for preventive and therapeutic strategies

The survival of herpes simplex virus in preserved murine corneas

International audienceBACKGROUND/AIMS: This study investigates the survival of HSV in infected mouse corneas, in the conditions of normal human eye bank preservation. METHODS: Hundred seventy-two BALB/C mice infected with herpes simplex virus 1 (HSV-1) (KOS) were randomly assigned to either: no preservation in group 1 (n = 62), 31 degrees C preservation for 3 weeks in group 2 (n = 70) or 4 degrees C preservation for 8 days in group 3 (n = 40). The presence of HSV-1 was thereafter detected by viral culture and PCR. RESULTS: In groups 1, 2 and 3, HSV-1 was detected by culture in 22 (35.5%), 1 (1.4%) and 0 (0.0%) of the corneas, and by PCR in 27 (43.7%), 3 (4.2%) and 7 (17.5%) of the corneas respectively. When compared to group 1, HSV was detected significantly less often in groups 2 (p < 0.0001) and 3 (p < 0.0001). CONCLUSIONS: HSV-1 DNA undergoes a degradation during corneal preservation

CONSERT probing of 67P/C-G nucleus during the ROSETTA mission, operations and results

International audienceThe structure and composition of cometary nuclei is one of the major unknowns in cometary science. These were the scientific objectives of the Comet Nucleus Sounding Experiment by Radiowave Transmission (CONSERT) aboard ESA spacecraft Rosetta. The knowledge of the interior is important to understand the formation and evolution of comets. CONSERT was a bi-static radar composed of two parts, one on the lander Philae on the comet’s surface, and another on Rosetta spacecraft (Kofman et al., 2007). CONSERT operated during 9 hours after the landing and made measurements through the small lobe (head) of 67P/ C-G. The analysis and interpretation have been done using measurements of the propagation time of the signal through the comet, the shape of the received signals and then 3D modeling of the propagation through the comet. The modelling and the propagation time inside the comet permit to derive the bulk permittivity value (= 1.27) of the cometary interior (Kofman et al, 2015). Permittivity values for porous mixture of ices and dusts were compared with laboratory experimental values in order to obtain constraints on the possible constituents of the comet nucleus (ices, silicates and organics) and its porosity (70-85%). The minimum required content of carbonaceous material is 75 % in volume. This suggests that comets represent a massive carbon reservoir (Kofman et al., 2015, Herique et al., 2016). The shape of the signal, very close to the shape of the calibration one, shows that the scattering by inhomogeneities in the medium is not observable. This indicates that the interior is homogenous at the scale of few wavelengths (Kofman et al., 2015). 3D simulations of the signal propagation in non-homogeneous media have been run to define the sensitivity of CONSERT to inhomogeneities and to find constrains on the internal structures in terms of size and composition at a scale commensurate with the wavelength. Given the high bulk porosity of about 75% inside the sounded part of the nucleus, a likely model would be obtained by a mixture, at this 3-m size scale, of voids (vacuum) and blobs with material made of ices and dust with a porosity larger than 60%. The absence of any pulse spreading due to scattering allows us to exclude heterogeneity with higher contrast (0.25) and larger size (3m) (but remaining on the few wavelengths scale, since larger scales can be responsible for multipath propagation) (Ciarletti et al., 2017). Properties of meterscale inhomogeneities inside the comet are essential to understand cometary formation. The knowledge of the precise position of Philae on the comet, since the September 2016, permitted to improve the determination of the propagation paths inside the comet and therefore to describe better the interior. The influence of the close environment on antennas lobes and polarization was calculated using the Digital Terrain Model of the landing site and used to study the received signal power. We will describe shortly measurements that explored the interior of the comet, discuss results, their interpretation in terms of the internal structure and composition. References [1] Ciarletti et al, CONSERT constrains the internal structure of 67P at a fewmetre size scale, MNRAS, 469 (Suppl. 2), pp.S805-S817, 2017 [2] Herique et al, Cosmochemical implications of CONSERT permittivity characterization of 67P/CG, MNRAS 462, S516-S532, 2016 [3] Kofman et al, The Comet Nucleus Sounding Experiment by Radiowave Transmission (CONSERT). Space Science Reviews, Volume 128, Issue 1-4, 413-432, 2007 [4] Kofman et al, Properties of the 67P/Churyumov-Gerasimenko interior revealed by CONSERT radar, Science, 349, 6247 aab0639, 2015