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International audience; Context Crop rotations, within-field mixtures, and landscape mosaics including susceptible and resistant crops are three commonly adopted crop diversification strategies that can limit crop epidemics. Typically, the effects of crop diversification at these three scales have been studied separately, on single pathogen species, and with low environmental variability. Objectives We aim to compare the disease-limitation effect of these three types of crop diversification on two highly damaging fungal pathogens of wheat Puccinia recondita (WLR) and Zymoseptoria tritici (STB) and under varying weather conditions (warmer or cooler climate for WLR, wetter or drier conditions for STB). Methods We built a dynamic mathematical model of epidemics at the field scale (based on classical Susceptible-Exposed-Infectious-Removed epidemiological models) embedded in a spatially explicit landscape grid framework. We use it to simulate an agricultural landscape in which diversification translates into different proportions of wheat and resistant crops in the landscape. Results In our simulations, for both pathogens and in all weather conditions, within-field crop mixtures had the greatest impact in limiting epidemics, crop rotations were second-best, while landscape mosaics were the least effective. We also found that the threshold above which further addition of resistant plants to crop mixtures would not cause further disease limitation to be dependent on weather conditions. The more favorable the weather is for pathogens the more resistant plants are required. Conclusions Our findings imply that interactions between spatial scale of crop diversification, pathogen characteristics and weather conditions should be considered in order to maximize benefits from disease-regulation properties of diversified cropping systems under climate change.

Cerebral amyloid angiopathy-related inflammation (CAA-ri) is a rare manifestation related to CAA, thought to be more severe. We aimed to compare the clinical and radiological outcomes of CAA-ri and non-inflammatory CAA.We retrospectively included all patients with CAA-ri from 13 French centers. We constituted a sex- and age-matched control cohort with non-inflammatory CAA and similar disease duration. Survival, autonomy and cognitive evolution were compared after logistic regression. Cerebral microbleeds (CMB), intracerebral hemorrhage, cortical superficial siderosis and hippocampal atrophy were analyzed as well as CSF biomarker profile and APOE genotype when available. Outcomes were compared using Kaplan-Meier curves and log-rank tests.Data from 48 CAA-ri patients including 28 already reported and 20 new patients were analyzed. Over a mean of 3.1 years, 11 patients died (22.9%) and 18 (37.5%) relapsed. CAA-ri patients were more frequently institutionalized than non-inflammatory CAA patients (30% vs 8.3%, p 0.001); mortality rates remained similar. MMSE and modified Rankin scale scores showed greater severity in CAA-ri at last follow-up. MRI showed a higher number of CMB at baseline and last follow-up in CAA-ri (p 0.001 and p = 0.004, respectively). CSF showed lower baseline levels of Aß42 in CAA-ri than non-inflammatory CAA (373.3 pg/ml vs 490.8 pg/ml, p = 0.05). CAA-ri patients more likely carried at least one APOE ε4 allele (76% vs 37.5%, adjusted p = 0.05) particularly as homozygous status (56% vs 6.2%, p 0.001).CAA-ri appears to be more severe than non-inflammatory CAA with a significant loss of autonomy and global higher amyloid burden, shown by more CMB and a distinct CSF profile. This burden may be partially promoted by ε4 allele.

Summary It is common during the exploration phase or at the early stage of a field development to work with a few of or even no well data, with uncertain Time or Velocity maps and with doubts about fault location. Lack of data and uncertain data decrease the robustness Depth-converted structural maps used in estimation of the field economic potential. Geostatistical methods developed in the framework of the UncerTZ RD Stochastic conditional simulations allow integrating uncertainty on Time or Velocity maps and on fault location. They also allow quantifying the global uncertainty resulting from all the uncertainties on data. With these methods, it is possible to get usable results from which the uncertainty on extension and volumes of petroleum traps can be estimated, allowing stakeholders to take the most appropriate decisions about field development.

Le service médical de psychologie clinique appliquée à l’aéronautique assure depuis plus d’un demi-siècle la prise en charge du personnel navigant militaire et civil selon un triple objectif : la préservation de la santé individuelle et collective, le soutien des forces opérationnelles et l’optimisation de la sécurité des vols. Par sa prise en compte du facteur humain, d’une part, et sa volonté de promouvoir la santé des aviateurs, d’autre part, l’état-major de l’armée de l’Air a créé et positionné au service médical de psychologie clinique appliquée à l’aéronautique un dispositif spécifique : la cellule de soutien médico-psychologique de l’armée de l’Air. Au cours de dix années d’expérience, la cellule s’est forgée une pratique clinique désormais reconnue par la communauté des aviateurs. Le nombre annuel des sollicitations après événements graves a doublé à partir de 2012 : en 10 ans d’activité, près de 150 interventions ont été menées dans ce contexte. Dans ce travail, nous définissons le soutien médico-psychologique après événement grave que nous illustrons d’exemples ; puis, nous abordons les cadres techniques et pratiques du soutien psychologique opérationnel. Enfin, nous évoquons les autres missions de la cellule (consultations ambulatoires, actions de sensibilisation et de formation, activités de recherche et de communication scientifique).

Adsorption of Acacia gums (GA) (A. senegal and A. seyal) and A. senegal molecular fractions, made of arabinogalactan-proteins (AGPs) with different molecular weights, onto latex particles, with different sizes and surface charges, was studied using molecular (fluorescence and nanoIR spectroscopies, microscopies including Atomic Force Microscopy) and mesoscopic (Dynamic Light Scattering, zeta potential, Asymmetrical flow field-flow fractionation) methods. Adsorption of GA onto latex particles revealed a complex mechanism of adsorption where the highest adsorption was observed when A. senegal and latex particles were negatively charged. The invert was observed for A. seyal where the maximum of adsorption was observed when gum and latex were oppositely charged. The duality of positive and negative charges on GA macromolecules together with conformational changes certainly explain the complex mechanism of adsorption. A mechanism where either the protein moiety either the sugars blocks adsorb is to be preferred. This mechanism seems to produce differences of behaviour due to viscoelastic properties of adsorbed layers, and differences of hydration due to differences of polarity of AGPs. The consequence of electrostatics in the adsorption process is a water release from the adsorbed layers and important gain in entropy. A fair agreement was found between protein content and adsorbed layer thickness of GA, with the formation of partial coverage, monolayer and multilayer films depending on GA concentration. Structural changes induced by GA adsorption onto latex particles was probed using fluorescence and nanoIR spectroscopies without giving clear evidence of conformational changes induced after GA adsorption. The results of this study highlighted that GA surface adsorption process depend not only on the protein moiety and electrostatic interactions but also on other parameters related to AGP hydration status. The protein structural accessibility, the molecular weight distribution, the AGPs intrinsic viscoelastic properties allowing structural rearrangements on the surface and spreading in order to form a viscoelastic film onto latex particles should also play a pivotal role in the adsorption process.

Cerebral microbleeds (CMBs) are small foci of (acute, subacute or chronic) blood products, best seen using magnetic resonance imaging (MRI) techniques sensitive to iron deposits (i.e. gradient-echo T2*-weighted and susceptibility-weighted imaging), frequently encountered in small vessel disease (SVD) (with hypertensive vasculopathy and cerebral amyloid angiopathy as the most frequent conditions) and also in other disorders. In this review, the MRI characteristics of CMBs and the associated MRI abnormalities encountered in common and less common SVD and non-SVD conditions are the main focus. Identification of the origin of CMBs depends on their localization, the presence of other associated MRI abnormalities, and the patient's history and clinical state.

Summary Faults are objects interpreted from seismic data that are often difficult to characterize. Not only the type of a fault can appear different depending on the domain the modeler is working on (time or depth), but accurate shape mapping often extends below the level of coherent seismic data. This proves especially impactful when we consider that simple errors in the fault-network characterization can render a subsurface model useless in terms of its flow properties and provide erroneous values for volumes of reserves. Nevertheless, in absence of proper technology, depth conversion workflows do not account for fault uncertainties, instead relying on a single deterministic interpretation. This paper presents a new methodology that considers positional fault uncertainty in time-to-depth conversion workflows. By considering different realizations of a fault, the target surface is dynamically adapted to this new position and can be used to update further volumetric computations. The proposed methodology can be fully automated and results in a more complete exploration of the uncertainty space regarding fault interpretation.

A water table mapping method that accounts for surface-water–groundwater (SW-GW) connectivity and human pressure, such as pumping and underground structures occurrence, has been elaborated and tested in the heavily urbanized Parisian area. The method developed here consists of two steps. First, hard data (hydraulic head) and soft data (dry wells) are used as conditioning points for the estimation of the SW-GW connection status. A disconnection criteria of 0.75 m is adjusted on observed unsaturated zone depth (UZD). It is a default value in areas where such data are missing. The second step consists of the final mapping of the water table. Given the knowledge of the disconnection criteria, the final map is achieved with an ordinary kriging of the UZD that integrates the surface water elevation without unsaturated zone where it is relevant. The methodology is demonstrated on two datasets of UZD observations that were collected under low- and high-flow conditions.

To optimize hydrocarbons recovery and quantify future production risks, it is necessary to accurately characterize traps geometry. This geometry is estimated from both seismic and well data, using Time-Depth conversion methods. This characterization is a critical issue in reservoirs with thin beds, as the uncertainty on horizons depth can lead to large variations of beds thickness. The paper presents an application on real data of a new Time-Depth conversion integrated workflow which is based on advanced geostatistical estimation and simulation multivariate algorithms and on automatic Spill Point recognition. It enhances horizons depth estimation and minimizes the uncertainty on the consecutive horizons. This workflow is extremely efficient in faulted layer-cake deposits, especially when reservoirs are thin. First, the theoretical background of the geostatistical multivariate algorithm is briefly summarized, including its version in the Bayesian framework. Then, the application example is used to highlight the differences between the simultaneous conversion of consecutive horizons and the standard conversion where horizons are considered as independent to each other. Focus is put on the vertical evolution of uncertainty and on the Geophysicist input allowed by the Bayesian framework. The workflow is versatile enough to convert directly Time in Depth or to compute intermediate enhanced velocity models when required. Practical examples are presented to illustrate the characteristics of each method. The impact of the different conversion options on Spill Points location and on the reservoirs Gross Rock Volumes are highlighted. One of the most original and useful features of the workflow is its ability to include faults location uncertainty in the global Gross Rock Volumes uncertainty quantification. The implementation of this capability is explained and illustrated from its application to real data. In the end, the impact on ultimate recovery uncertainty is analyzed and illustrated from a practical case study.

International audience; We used a droplet-based microfluidics technique to produce monodisperse responsive alginate-block-polyetheramine copolymer microgels. The polyetheramine group (PEA), corresponding to a propylene oxide /ethylene oxide ratio (PO/EO) of 29/6 (Jeffamine (R) M2005), was condensed, via the amine link, to alginates with various mannuronic/guluronic acids ratios and using two alginate:jeffamine mass ratios. The size of the grafted-alginate microgels varied from 60 to 80 mu m depending on the type of alginate used and the degree of substitution. The droplet-based microfluidics technique offered exquisite control of both the dimension and physical chemical properties of the grafted-alginate microgels. These microgels were therefore comparable to isolated grafted-alginate chains in retaining both their amphiphilic and thermo-sensitive properties. Amphiphilicity was demonstrated at the oil-water interface where grafted-alginate microgels were found to decrease interfacial tension by similar to 50%. The thermo-sensitivity of microgels was clearly demonstrated and a 10 to 20% reduction in size between was evidenced on increasing the temperature above the lower critical solution temperature (T-LCST) of Jeffamine. In addition, the reversibility of thermo-sensitivity was demonstrated by studying the oil-water affinity of microgels with temperature after Congo red labeling. Finally, droplet-based microfluidics was found to be a good and promising tool for generating responsive biobased hydrogels for drug delivery applications and potential new colloidal stabilizers for dispersed systems such as Pickering emulsions. (C) 2015 Elsevier B.V. All rights reserved.

On behalf of the 90th birthday of Professor Glyn O. Phillips, it is a great honor for authors of this publication to make a review on Acacia gum, one of the favorite polysaccharides extensively studied by Glyn and his collaborators all around the world during these last five decades. After remembering a synthetic historical perspective, the present critical review summarizes the main updated data of this complex polysaccharide from the chemical composition to the functional properties with a particular attention toward structure and bulk and interfacial properties. Biological properties of Acacia gums were not considered. Some of the main challenges in a near future for a better understanding of the functional properties of this polysaccharide concerns the detailed study of the gum maturation mechanism upon exudation, the structure and conformation of different molecular fractions, the role of minor components (minerals, polyphenols, lipids) on the structure and functionality of gums, the physicochemical properties of purified molecular fractions and the ways to modified them upon enzymatic modifications. In our opinion, the main challenges for a better understanding of the interfacial function of this polysaccharide (adhesion and stabilization at liquid and solid interfaces) will be to probe the interfacial induced conformational changes. This area of research seems to have been quite neglected during these last past years and fundamental questions arising from the adhesive and stabilizing properties of Acacia gum are still without answer today. In addition, the amino-acid sequence contained in this complex polysaccharide are totally unknown today and future developments based on enzyme/chemical modifications and liquid chromatography coupled to on line mass spectrometry could unravel the sequence and decipher between the existence of one or more amino-acid sequences in Acacia senegal gum. We sincerely hope Glyn, one of the “father of Arabic gum”, will find some positive echo in this review.

Background The efficacy of enzyme replacement therapy (ERT) in patients at an advanced stage of Pompe disease has only been addressed in a few studies. Our objective was to assess the long term effects of ERT in a cohort of patients with severe Pompe disease. Methods We identified patients from the French Pompe Registry with severe respiratory failure and permanent wheelchair use (assisted walk for a few meters was allowed) when starting ERT. Patients' medical records were collected and reviewed and respiratory and motor functions, before ERT initiation and upon last evaluation were compared. Results Twelve patients (7 males) were identified. Median age at symptom onset was 24 years [IQR = 15.5; 36.0]. At baseline ventilation was invasive in 11 patients and noninvasive in one, with a median ventilation time of 24 h [IQR = 21.88; 24.00] (min 20; max 24). ERT was initiated at a median age of 52.5 years [IQR = 35.75; 66.50]. Median treatment duration was 55 months [IQR = 39.5; 81.0]. During observational period no adverse reaction to ERT was recorded, five patients (41.67%) died, three decreased their ventilation time by 30, 60 and 90 min and two increased their assisted walking distance, by 80 and 20 m. Conclusion Some patients at a very advanced stage of Pompe disease may show a mild benefit from ERT, in terms of increased time of autonomous ventilation and of enlarged distance in assisted walk. ERT can be initiated in these patients in order to retain their current level of independence and ability to perform daily life activities.

Laser Weapon (Directed Energy) Systems are experiencing increased interest and nearing deployment. The latest technology research to address these applications is reviewed. Progress with ongoing research activities and remaining challenges will be discussed.

This study investigated the infection process of Mycosphaerella graminicola and enzyme activities related to reactive oxygen species (ROS) or oxylipin biosynthesis in four French wheat cultivars with variable resistance to M. graminicola infection. At field level, cultivars Caphorn, Maxyl and Gen11 were susceptible, whereas Capnor showed high levels of quantitative resistance. Moreover, Capnor and Gen11 were tolerant, i.e., their yield was less affected by infection compared to non-tolerant Maxyl and Caphorn. These four cultivars were inoculated under laboratory conditions with the M. graminicola IPO323 reference strain. Cytological and biochemical responses were studied on collected first plantlet leaves and several features discriminated between cultivars. However, resistance and tolerance had no impact on the fungal infection process. Levels of lipoxygenase (LOX), peroxidase (PO) and glutathione-S-transferase (GST) activities were also compared with regard to cultivar resistance or tolerance to M. graminicola. LOX, PO and GST activities did not discriminate resistance and tolerance profiles, although a low level of PO in inoculated and non-inoculated plants could be associated with tolerance. In addition, cell necrosis correlated positively with LOX in non-tolerant cultivars, while mycelia surrounding stomata were positively correlated with PO in the resistant cultivar. GST activity presented correlations between cytological and biochemical parameters only for susceptible cultivars. Stomatal and direct penetration were positively correlated with GST activity in the susceptible non-tolerant cultivars, while these correlations were negative in the tolerant cultivar. When combining cytological and biochemical observations with resistance and tolerance profiles, for each cultivar and at each time point, cultivars could be classified in tight accordance with their previous field characterisation. Moreover, tolerance allowed us to distinguish susceptible cultivars when both biochemical and cytological parameters were considered together.

In wheat, little is known about disease resistance inducers and, more specifically, about the biological activities from those derived from endogenous elicitors, such as oligogalacturonides (OGAs). Therefore, we tested the ability of two fractions of OGAs, with polymerization degrees (DPs) of 2–25, to induce resistance to Blumeria graminis f. sp. tritici and defense responses in wheat. One fraction was unacetylated (OGAs–Ac) whereas the second one was 30% chemically acetylated (OGAs+Ac). Infection level was reduced to 57 and 58% relative to controls when OGAs–Ac and OGAs+Ac, respectively, were sprayed 48 h before inoculation. Activities of various defense-related enzymes were then assayed in noninoculated wheat leaves infiltrated with OGAs. Oxalate oxidase, peroxidase, and lipoxygenase were responsive to both OGAs–Ac and OGAs+Ac, which suggests involvement of reactive oxygen species and oxilipins in OGAs-mediated responses in wheat. In inoculated leaves, both fractions induced a similar increase in H2O2 accumulation at the site of fungal penetration. However, only OGAs+Ac led to an increase in papilla-associated fluorescence and to a reduction of formed fungal haustoria. Our work provides the first evidence for elicitation and protection effects of preventive treatments with OGAs in wheat and for new properties of acetylated OGAs.

This report describes the measurement, reduction, and basic analysis of transport layer protocol (transmission control protocol and user datagram protocol) data collected from large-scale tactical radio network tests. The large volume of data collected necessitates using distributed processing on high-performance-computing (HPC) clusters to reduce and analyze data in a timely fashion. Traditional methods using database ingest and queries on high-end servers cannot handle the increasing scale of current datasets, and processing times are estimated to be on the order of days versus hours using HPC. The requirement for the use of HPC was anticipated, and efforts to develop this capability resulted in a highly capable process that is expected to handle future large-scale tactical network testing.

Over the past 2 years the US Army Test and Evaluation Command, Aberdeen Test Center, has worked in close collaboration with the US Army Research Laboratory's Computational and Information Sciences Directorate to utilize high-performance computing to build a system-of-processes to reduce large volumes of data recorded in a high-bandwidth tactical network test environment. This introductory report will describe the nature of a tactical ad-hoc network, how such an aggregate is tested in field events, and the types of refined products and analysis performed on collected data. The report will also introduce a series of reports written about this system-of-processes, in which each report describes in more detail specific aspects of the processing.

Teams from the Aberdeen Test Center and the US Army Research Laboratory collaborated to design and build a system-of-processes with a goal of reliably marshalling data from a large-scale remote tactical network field test, shuttling the data cross-country, and performing reduction and analysis. The progression of going from terabytes of raw collected field data to a data product that can be used by analysts and evaluators required coordination of people and hardware from several cross-country sites. This system-of-processes reliably worked over a 2-month time span, processing an average of 1.5 TB of raw field-collected data a day. This report describes methods, processes, and systems employed to go from raw data to a finished data product in a short time period (several days) to facilitate Army decision making on a major communications system production.

Arabinogalactan (AG) and arabinogalactan-protein (AGP) fractions were treated enzymatically using several proteases in acidic (pH 4) and alkaline (pH 7) conditions in order to go deeper insight into the structure and conformations of the two main fractions of Acacia senegal gum. Endoproteinase Glu-C, pepsin and phosphatase acid were thus used in acidic conditions while subtilisin A, pronase, trypsin, papain and proteinase K were used in alkaline conditions to cleave protein moieties of the two fractions. Structures of AG and AGP were probed using HPSEC-MALLS, small angle neutron scattering and far-UV circular dichroism. [br/] Enzymes did not affect AG fraction structure whatever the pH conditions used, highlighting the inaccessibility of the peptide backbone and the remarkable stability of this fraction in acidic and alkaline conditions. This result was in agreement with the thin oblate ellipsoid model we previously identified for the AG fraction where the 43 amino-acid residues peptide sequence was supposed, based on spectroscopic methods, to be totally buried. [br/] Contrary to AG fraction, AGP protein component was therefore cleaved using enzymes in alkaline conditions, the absence of enzymatic efficiency in acidic conditions being probably ascribed to long range electrostatic repulsions occurring between negatively charged AGP and enzymes at pH 4. The decrease of AGP molecular weight after hydrolysis in alkaline conditions went from 1.79 x 10(6) gmol(-1) for control AGP to as low as 1.68 x 10(5) g mol(-1) for papain-treated AGP. The overall structure of the enzyme-treated AGPs was found to be surprisingly quite similar whatever the enzyme used and close, with however some subtle differences, to AG unit. A tri-axial ellipsoid conformation was found in enzyme-treated AGPs and the two main preferential distances identified in the pair distance distribution function would claim in favor of rod-like or elongated particles or alternatively would indicate the presence of two particles differing in dimensions. The secondary structures content of control and enzyme-treated AGPs were similar, highlighting both the high rigidity of the protein backbone and the overall symmetry of AGP. This conclusion was reinforced by the more compact structures found when AGP was intact compare to the more elongated structures found when AGP was enzymatically cleaved. [br/] Finally, the structural similarities found in enzyme-treated AGP together with the theoretical calculations to analytically probe the type of branching would suggest that AGP would be made of a self-similar assembly of two types of building blocks, the second being a five-fold repetition of the first one, for which palindromic amino acid sequence would ensure a self-ordering of carbohydrate moieties along the polypeptide chains. The cleavage would therefore lead to hydrolysed building blocks with similar secondary structures and conformations whatever the enzyme used.

This paper is a comprehensive study of different formalisms used to simulate polar magneto-optical (MO) effects in multilayers. A development of the 4 × 4 matrix calculation to first order in off-diagonal elements of the permittivity tensor gives original analytical expressions. They allow to express the MO effects in multilayers as a sum of contributions from individual layers. Each contribution consists of two components assigned to the interface and propagation effects. The explicit expressions for multilayers containing up to seven layers, together with those obtained in the frame of an ultrathin layer approximation, are shown to be useful both in a qualitative comprehension and in quantitative simulations of the experimental MO Kerr spectra of a wide variety of ultrathin magnetic structures. They can be used to separate the different contributions arising from the interfaces due to intermixing or spin polarization (including interface roughness) as well as to simulate magnetically coupled multilayers. As an example, the analytical expression is provided for a system consisting of two ultrathin films separated by a non-magnetic spacer and deposited on a non-magnetic substrate. The capabilities of the analytical expressions are demonstrated on MO spectroscopy in a broad spectral range of some well characterized ultrathin magnetic structures.

Secondary ion mass spectroscopic analysis of insulators is difficult because charging of the sample affects the trajectories of primary and secondary ions. Analysis of alkali elements in insulators is additionally complicated by the mobility of the species of interest under the influence of an electric field. Magnetic sector analyzers also present difficulties in providing charge neutralization because of the high electric field required to inject ions into the analyzer. Coating of the sample with a conductive film or grid has often been needed to provide a meaningful analysis. However, coating the sample adds a contaminant source that complicates alkali analysis, especially at the concentrations of interest to the semiconductor industry. In this article we provide, for a magnetic sector instrument, a method that requires no coating or sample preparation prior to analysis. If the electron penetration depth is matched to the thickness of the oxide layer, results show that SiO2 layers from 0.3 to 1.36 μm th...

We report here on resistance and magnetoresistance (MR) studies of ultrathin Co/Au(111) single sandwiches and bilayers with perpendicular magnetization. Resistance of the films was measured in situ in ultrahigh vacuum, during depositions and as a function of a perpendicular applied magnetic field. A large MR variation with the thickness of Au coverage was observed and compared to calculations. The coercive field of the Co films shows a drastic variation with the Au coverage thickness, which reflects the theoretical anisotropy variation. It was measured as a function of temperature. For the first time, the effect of interlayer interaction on the resistivity of a Co bilayer during the growth of Co top layer, is evidenced and compared to calculations. Finally, hysteresis loops of strongly antiferromagnetically coupled bilayers are investigated.

Resume Introduction L’evolution de l’oxygenation musculaire evaluee avec la technique de spectroscopie du proche infrarouge a ete utilisee pour fournir des informations sur la cinetique de l’utilisation de l’oxygene au niveau musculaire au debut de l’exercice. Synthese des faits Le temps de reponse globale de l’augmentation de la desoxygenation musculaire n’etait pas modifie par l’hyperoxie (19,6 ± 2,3 secondes en hyperoxie versus 20,6 ± 2,8 secondes en normoxie, NS). Conclusion Ce resultat suggere que l’hyperoxie n’induisait pas d’acceleration de la cinetique de l’utilisation de l’oxygene au niveau musculaire et donc que la disponibilite en oxygene n’est pas le facteur limitant cette cinetique.

A new experiment for ‘in situ’ measurements of the resistance of thin metallic films during their deposition has been carried out. A coil installed in the vacuum chamber produces a variable magnetic field in order to study also the magnetoresistance of magnetic films. The first results obtained with the Au/Co system are presented. We show that the magnetoresistance effect increases when a gold coverage restores a good reflectivity for the conduction electrons. The coercive field of ferromagnetic cobalt layers depends on the coverage thickness, in good agreement with previous studies.

Magnetization-reversal processes in a ferromagnetic cobalt film structure (Au/Co/Au), with perpendicular anisotropy, were investigated by magneto-optical magnetometry and microscopy. In the considered ultrathin Co film, the magnetization reversal between the two Ising-spin equilibrium states is dominated by the domain-wall motion mechanism. We focused our studies on processes initiated from a given demagnetized state. Starting from a magnetically saturated state generated under a large field ${\mathrm{H}}_{\mathrm{S}}$, applied perpendicular to the film, this demagnetized state is created through magnetic aftereffects in a field ${\mathrm{H}}_{\mathrm{d}}$ antiparallel but smaller than ${\mathrm{H}}_{\mathrm{S}}$ and applied during a selected time. Direct (${\mathrm{R}}^{\mathrm{D}}$) and indirect (${\mathrm{R}}^{\mathrm{I}}$) magnetization processes are then studied from this state for application of the field parallel and antiparallel to ${\mathrm{H}}_{\mathrm{d}}$, respectively. The dynamics of the magnetization reversal is much faster for the ${\mathrm{R}}^{\mathrm{I}}$ process since it is initiated from a quasihomogeneous 'Swiss cheese' domain state with small nonreversed regions. The magnetic accommodation phenomenon is studied, and a domain-shape memory effect evidenced. A theoretical analysis of the dynamics of magnetization processes is proposed, starting from the model of a patchy inhomogeneous media with a realistic distribution of local coercivities. The pertinent parameters for calculations are deduced from our experimental data using appropriate analytical expressions of the magnetic relaxation time and domain-wall velocity under a field. Computer simulations using these parameters reproduce well the time evolution of the magnetic domain pattern and different magnetization curves both for ${\mathrm{R}}^{\mathrm{D}}$ and ${\mathrm{R}}^{\mathrm{I}}$ magnetization processes.

The first part of this paper is devoted to the electrical characteristics of the air below the canopy of a pine and spruce forest. In fair weather conditions, the site influence, i.e. the filtering effect of the trees on air conductivity and electric field, is evidenced. Under disturbed weather conditions, the meteorological influence is depicted to show: (i) that electric fields sufficiently high to produce `point discharges' occur not only during thunderstorms but also during mist; (ii) that, by taking into account the gaseous ions produced by the point discharges, it becomes possible to understand on the one hand the field divergence with height observed in the mist, and on the other hand the detection of alternatively positive and negative gaseous clouds of charges during the thunderstorm. The second part presents the results of chemical analysis performed below and just above the canopy on the same site and for the same period. Increased ozone and hydrogen peroxide concentrations were measured during the thunderstorm. It is shown that these chemical species were not only locally produced by photochemistry and/or transported from different (industrial and traffic) sources, but also arose from transient electrical point discharges in the forest under high electric field conditions. Their local concentration is shown to be influenced by the electrical discharge current density on the one hand, and by the local conditions of atmospheric stability and of water content, determining the evolution of the chemical products, on the other hand. Actually, after their production, the initially gaseous chemical products were shown to be involved in the local droplet chemistry. Under specific weather conditions, ionic densities as well as chemical by-products of a forest therefore depend both on the electrodynamical characteristics of the lower atmosphere and on the local environmental conditions (liquid water content of the air and atmospheric stability) associated with the two different situations investigated, a mist and a thunderstorm.

Polar magnetooptics (MO) is able to probe the magnetization depth profile in ultrathin magnetic film structures on a nanometer scale. This information can be deduced by modelling the MO effects in the considered layered medium when performing MO experiments with a compensator or changing the wavelength of the incident light beam. Spectroscopic MO measurements are then helpful for analysing this phenomenon in detail. The in-depth selectivity of MO effects for magnetization is demonstrated for a simple ultrathin film structure consisting of two magnetic Co layers with perpendicular anisotropy separated by a non-magnetic Au spacer layer. The individual magnetic contributions of the two Co layers may be observed directly when performing MO Kerr measurements at selected compensator phase shifts or photon energies. The experimental data are interpreted by MO calculations in both cases.

Capillary flow-based approach such as microfluidic devices offer a number of advantages over conventional flow control technology because they ensure highly versatile geometry and can be used to produce monodisperse spherical and non-spherical polymeric microparticles. Based on the principle of a flow-focusing device to emulsify the coflow of aqueous solutions in an organic phase, we were able to produce the following innovative polysaccharide hydrogel microparticles: - Janus hydrogel microparticles made of pectin–pectin (homo Janus) and pectin–alginate (hetero Janus) were produced. The efficiency of separation of the two hemispheres was investigated by confocal scanning laser microscopy (CSLM) of previously labelled biopolymers. The Janus structure was confirmed by subjecting each microparticle hemisphere to specific enzymatic degradation. As a proof of concept, free BSA or BSA grafted with dextran, were encapsulated in each hemisphere of the hetero Janus hydrogel microparticles. While BSA, free or grafted with dextran, was always confined in the alginate hemisphere, a fraction of BSA diffused from the pectin to the alginate hemisphere. Methoxy groups along the pectin chain will be responsible of the decrease of the number of attractive electrostatic interactions occurring between amino groups of BSA and carboxylic groups of pectin. - Pectin hydrogel microparticles of complex shapes were successfully produced by combining on-chip the phenomenon of gelation and water diffusion induced self-assembly, using dimethyl carbonate as continuous phase, or by deformation of the pre-gelled droplets off-chip at a fluid–fluid interface. Sphere, oblate ellipsoid, torus or mushroom-type morphologies were thus obtained. Moreover, it was established that after crossing the interface during their collect, mushroom-type microparticles did not migrate in the calcium or DMC phase but stayed at the liquid–liquid interface. These new and original hydrogel microparticles will open up opportunities for studying relationships between combined enzymatic hydrolysis and active release for Janus particles and relationships between shape and swelling behaviour for anisotropic pectin microparticles.

International audience; The glycoprotein (GP) molecular fraction structure of the gum exudate of Acacia senegal (gum Arabic) isolated from hydrophobic interaction chromatography was investigated using high-performance size exclusion chromatography-multi angle laser light scattering (HPSEC-MALLS), small angle X-ray scattering (SAXS), synchrotron radiation circular dichroism (SRCD) and transmission electron microscopy (TEM) observations. In solution, GP would be a mixture of spheroidal monomers and more anisotropic oligomers as suggested by the two exponent values found in the R-g vs. M-w relationship and TEM observations. The GP conformation probed by SAXS was ascribed to a thin object with a triaxial ellipsoid morphology, certainly attributed to GP oligomers. A 9 nm diameter particle was also identified by SAXS in agreement with the dimensions identified by TEM on single isolated ring-like structures. The GP oligomerization process, as probed by TEM, would be the result of ring-like subunits self-association. This self-association would lead to more linear or, sometimes, cyclised assembly. At the molecular level, GP fraction was found to have secondary structures mainly made of beta-sheets and turns (64%) but also, to a lesser extent, made of polyproline II (PPII) and alpha-helices (19%). These features were characteristic of hydroxyprolin-rich glycoproteins with arabinosylated and arabinogalactan polysaccharide side chains grafted to the polypeptide backbone. The GP molecular fraction structure from Acacia gum would be an assembly of ring-like glycoproteins modules. These ring-like structures were certainly due to hydroxyproline (Hyp)-arabinogalactan (AG) subunits. Crown Copyright (C) 2013 Published by Elsevier Ltd. All rights reserved.

In some of the methods used in metallography, the signal-noise ratio is so low that direct interpretation is not possible. With regard to microanalysis, the segregation in steels is currently being studied using quantitative X-ray mapping. The acquisition time and counting statistics are limiting factors, particularly for elements in low concentration that present low count rates compared with the background level. Noise from the useful information can be filtered out by geostatistical techniques. A new commercial software, IMAGEO, has been developed by the Ecole des Mines de Paris for noise filtering and signal deconvolution. The main features of this method and the software are described with detailed application examples. With this technique, it is now possible not only to get information from images that would be unusable, but, in the case of microanalysis, to save time for elements in higher concentration by using less counting time.

For a better understanding of optical interactions in magnetic layered structures we establish general expressions of both polar Kerr and Faraday first-order magneto-optical (MO) effects. The approach presented here enables the MO response of an arbitrary magnetic layer system to be analytically expressed with an accuracy practically equal (less than ${10}^{\mathrm{\ensuremath{-}}4}$ deg) to that of the full matrix calculations usually employed for modeling MO effects in magnetic multilayers. The formulas for any particular structure are obtained from general MO expressions by introducing associated reflection and transmission coefficients. This procedure is justified here in the simple case of an ultrathin magnetic film sandwiched between two nonmagnetic layers. These accurate expressions are further simplified for ultrathin magnetic films and the limitations of this approximation discussed. The simplified formulas are then used to analyze MO polar Kerr and Faraday data in well-defined Au (5 nm)/Co/Au (25 nm) structures, grown on float glass substrates. The Co layer thicknesses are chosen in the range 0.4--2.0 nm to preserve a perpendicular magnetic anisotropy. The simplified expressions, as well as the numerical modeling of the trends in MO spectra with a variation of the overlayer or buffer layer thicknesses, show that the shape of the polar Kerr effect spectrum is mainly dependent upon the optical properties of the Au buffer layer whereas the observed MO amplitudes are reduced consistently with the absorption of the Au overlayer.

CoAu multilayers, eight in all, with between two and nine cobalt layers, were produced together in UHV by thermal evaporation. All cobalt layers were identically thick (0.8 nm) with easy magnetisation axis perpendicular to the film plane. The (111) gold interlayer thickness of 2.2 nm corresponds to an antiferromagnetic coupling [1]. Kerr rotation magneto-optics and magnetoresistance measurements under perpendicular magnetic field revealed separate coercive fields for each of the cobalt layers. The plateaux between two coercive fields represent different magnetisation direction configurations that could be identified by the magnetoresistance measurements. An adapted Camley—Barnas modelling of the multilayers with up to six cobalt layers was conducted which agreed well with experimental results and further confirmed the magnetisation reversal order deduced by the magnetoresistance measurements.