Search

25 p. This study was carried out to determine the occurrence and characteristics of enteropathogenic 18 Escherichia coli (EPEC) and Shiga toxin-producing E. coli (STEC) strains in cow’s milk, cheese 19 and dairy cattle farm environments, and to estimate distribution of antimicrobial resistance. A 20 collection of 18 atypical EPEC -aEPEC, 14 STEC, and one E. albertii was obtained and 21 characterized from 502 samples. Occurrence of aEPEC in cow’s milk was high (>6%) whereas non- 22 O157 STEC was isolated in ca. 2% of milk samples. Detection of these diarrheagenic E. coli was absent in more than 100 cheese samples obtained from raw milk. This is the first 23 report identifying 24 E. albertii (O69:HNM) in a dairy cattle farm. Nearly one-third of aEPEC strains showed 25 antimicrobial resistance, mostly presenting a multidrug resistance pattern. One clonal complex 26 (ST20 Cplx) containing aEPEC strains from milk and faecal samples was determined. Two STEC 27 strains belonged to serotypes with importance in human disease (O91:H21 and O55:H8) and were 28 isolated from air samples which suggests a high dissemination potential. Spanish bulk tank cow’s 29 milk can constitute an important source of aEPEC strains besides STEC, bearing multiple 30 antimicrobial resistance and with high diversity of both serotypes and genetic features linked to 31 potential human infection SI

The role of wildlife in the epidemiology of antimicrobial resistance is unclear. Raccoons in North America can carry a variety of enteric bacteria, with associated antimicrobial resistance, that could infect humans and livestock. The potential for raccoons to carry these bacteria in Europe, where they are an invasive species, has not been explored. Our objectives were to determine the prevalence of Escherichia coli with associated antimicrobial resistance in raccoons from the Madrid region of Spain and to determine whether they are carriers of potential human pathogens, including verotoxin-producing E. coli (VTEC) and enteropathogenic E. coli (EPEC). In total, we tested 237 E. coli isolates from the faeces of 83 euthanized raccoons for susceptibility to 14 antimicrobial agents and the presence of VTEC and EPEC. Antimicrobial resistance to at least one antimicrobial was detected in the faeces of 51% (42/83; 95% CI, 40.1–61.1) of the raccoons tested. A high percentage of raccoons carried, in their faeces, E. coli isolates resistant to ampicillin (33%), streptomycin (33%), tetracycline (30%), sulphafurazole (31%) and trimethoprim-sulphamethoxazole (23%). We detected one isolate of extended-spectrum β-lactamase-producing E. coli from the faeces of one raccoon. We detected VTEC in the faeces of one raccoon, and EPEC in the faeces of 12% (10/83) of the raccoons. Of the raccoons that carried EPEC in their faeces, 60% (6/10) carried EPEC isolates that exhibited characteristics associated with pathogenicity in humans. Raccoons in Madrid can carry pathogenic and antimicrobial-resistant E. coli in their faeces and may be a risk to public health because of their potential to contaminate food and the environment with their faeces., Comunidad de Madrid (Spain), PI16/01477 from Plan Estatal de I+D+I 2013-2016, Instituto de Salud Carlos III (ISCIII), Subdirección General de Evaluación y Fomento de la Investigación and Fondo Europeo de Desarrollo Regional (FEDER), and ED431C2017/57 from the Consellería de Cultura, Educación e Ordenación Universitaria (Xunta de Galicia) and FEDER; Spanish Ministerio de Educación, Cultura y Deporte

Colistin is an antimicrobial polypeptide commonly employed for controlling and treating neonatal and post-weaning diarrhoea (PWD) diseases caused by Enterotoxigenic and Shiga toxin-producing Escherichia coli (ETEC and STEC). The plasmid-mediated colistin resistance gene, mcr-1 was first described in late 2015 and, since then, multiple studies have reported its global distribution. In addition, five different mcr genes have been identified. The aim of this study was to characterise the colistin-resistant E. coli clonal groups implicated in PWD in farms of intensive pig production. Of 186 ETEC and STEC isolated in Spain from 2006 to 2017, 76.9% showed resistance to colistin. Of those, 102 were mcr-4 carriers, 37 mcr-1 and 5 mcr-5, with co-occurrence of mcr-1/mcr-4, mcr-1/mcr-5 and mcr-4/mcr-5 in five isolates. Three different mcr-4 variants were detected, including the new mcr-4.4 and mcr-4.5 described here. Interestingly, the clonal group ST10-A (CH11-24) appears to be primarily responsible for the spread of mcr-4. In summary, our results show that the pig industry is an important reservoir of colistin-resistant E. coli, carriers of other additional risk genes, such as blaESBL. These food-producing animals might be spreading a cocktail of multiple resistances, posing a worrisome threat to human health.

International audience; CuCrZr is a precipitation hardening alloy, used for its good electrical and thermal properties combined to high mechanical properties. Using additive manufacturing technologies, and more specifically the laser powder bed fusion (L-PBF) process, allows designing highly complex parts such as compact and efficient CuCrZr heat exchangers. Additional understanding of the specific CuCrZr metallurgy during this manufacturing process is still needed to fully take advantages of these possibilities. This work aimed (i) to clarify the impact of the L-PBF process and post-fabrication heat treatments on the microstructure of L-PBF CuCrZr alloy, (ii) to determine the corresponding mechanical and electrical properties and (iii) to quantify the contributions of the different nano-scale strengthening mechanisms (nano-precipitation, dislocations, solid solution, grain size refinement) depending on the different heat treatments. The microstructures of the CuCrZr samples are carefully analyzed at different scales thanks to scanning electron and transmission electron microscopy, highlighting the effect of the different heat treatments. In all heat-treated samples, Cr nano-precipitates are uniformly dispersed in the Cu matrix; few Zr nano-precipitates are observed either at grain boundaries, next to Cr nano-precipitates, or inside the Cu matrix. Moreover, the mean grain size, dislocation density, mean radius and volume fraction of the Chromium nano-precipitates are measured. These data are introduced in the identified hardening mechanisms to estimate the yield strengths (YS) of the different analyzed CuCrZr microstructures. The results are compared to the experimental values, including those of a reference wrought heat-treated CuCrZr, and discussed. A good correlation is found between calculated and experimental values. For the first time, the main hardening mechanisms of L-PBF CuCrZr are quantified and the interest of the L-PBF+Direct Age Hardening (DAH) process route to get a high amount of Cr nano-precipitates is confirmed. The DAH applied to L-PBF materials provides high mechanical properties (184 HV1 hardness, YS=527 MPa, UTS=585MPa) while keeping a good elongation (14%) and electrical conductivity (42 MS.m-1). These results are due to a combination between (i) a high Cr nano-precipitates density, leading to a high precipitation hardening, and (ii) a high dislocation density associated to the presence of remaining solidification cells.

Self-synthesizing transposons are integrative mobile genetic elements (MGEs) that encode their own B-family DNA polymerase (PolB). Discovered a few years ago, they are proposed as key players in the evolution of several groups of DNA viruses and virus–host interaction machinery. Pipolins are the most recent addition to the group, are integrated in the genomes of bacteria from diverse phyla and also present as circular plasmids in mitochondria. Remarkably, pipolins-encoded PolBs are proficient DNA polymerases endowed with DNA priming capacity, hence the name, primer-independent PolB (piPolB). We have now surveyed the presence of pipolins in a collection of 2,238 human and animal pathogenic Escherichia coli strains and found that, although detected in only 25 positive isolates (1.1%), they are present in E. coli strains from a wide variety of pathotypes, serotypes, phylogenetic groups and sequence types. Overall, the pangenome of strains carrying pipolins is highly diverse, despite the fact that a considerable number of strains belong to only three clonal complexes (CC10, CC23 and CC32). Comparative analysis with a set of 67 additional pipolin-harboring genomes from GenBank database spanning strains from diverse origin, further confirmed these results. The genetic structure of pipolins shows great flexibility and variability, with the piPolB gene and the attachment sites being the only common features. Most pipolins contain one or more recombinases that would be involved in excision/integration of the element in the same conserved tRNA gene. This mobilization mechanism might explain the apparent incompatibility of pipolins with other integrative MGEs such as integrons. In addition, analysis of cophylogeny between pipolins and pipolin-harboring strains showed a lack of congruence between several pipolins and their host strains, in agreement with horizontal transfer between hosts. Overall, these results indicate that pipolins can serve as a vehicle for genetic transfer among circulating E. coli and possibly also among other pathogenic bacteria., This research was funded by the Spanish Ministry of Science, Innovation and Universities, Grant Number PGC2018-093723-A-I00 (AEI and FEDER, UE) to M.R.R., and by institutional grants from Fundación Ramón Areces and Banco de Santander to the Centro de Biología Molecular Severo Ochoa. LREC laboratory was supported by projects PI16/01477 from Plan Estatal de I + D + I 2013–2016, Instituto de Salud Carlos III (ISCIII), Subdirección General de Evaluación y Fomento de la Investigación, Ministerio de Economía y Competitividad (Gobierno de España) and Fondo Europeo de Desarrollo Regional (FEDER); and ED431C2017/57 from the Consellería de Cultura, Educación e Ordenación Universitaria (Xunta de Galicia) and FEDER. S.-C. F.-S. was holder of a PhD fellowship (FPU15/02644) from the Secretaría General de Universidades, Spanish Ministerio de Educación, Cultura y Deporte.

The prevalence of Shiga toxin (Stx)-producing Escherichia coli (STEC) was determined by evaluating its presence in faecal samples from 155 heifers, and 254 dairy cows in 21 farms at North of Portugal sampled between December 2017 and June 2019. The prevalence of STEC in heifers (45%) was significantly higher than in lactating cows (16%) (p, This study was financially supported by: i) project PhageSTEC (POCI-01-0145 -FEDER 029628) funded by FEDER through COMPETE2020 (Programa Operacional Competitividade e Internacionalizac¸ão) and by National Funds thought FCT (Fundac¸ão para a Ciência e a Tecnologia); ii) strategic project UIDB/04469/2020 unit and BioTecNorte operation (NORTE-01-0145-FEDER 000004) funded by FCT under the scope of the European Regional Development Fund (Norte2020 - Programa Operacional Regional do Norte); iii) project PI16/01477 from Plan Estatal de I+D+I 2013-2016, Instituto de Salud Carlos III (ISCIII), Subdireccio´n General de Evaluacio´n y Fomento de la Investigacio´n, Ministerio de Economı´a y Competitividad (Gobierno de España) and FEDER; and iv) grant ED431C2017/57 from the Consellerı´a de Cultura, Educacio´n e Ordenación Universitaria, (Xunta de Galicia) and FEDER; UIDB/AGR/04033/2020 by National Funds thought FCT. Author IGM acknowledges the Consellerı´a de Cultura, Educacio´n e Ordenacio´n Universitaria, Xunta de Galicia for the individual grant ED481A-2015/149 and and author SCFS acknowledges the FPU programme for the individual grant FPU15/02644 from the Secretarı´a General de Universidades, Spanish Ministerio de Educacio´n, Cultura y Deporte. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript., info:eu-repo/semantics/publishedVersion

This is a wide epidemiological study of 499 E. coli isolates recovered from 179 outbreaks of enteric colibacillosis from pig production farms in Spain during a period of 10 years. Most samples were of diarrheagenic cases occurred during the post-wean period (PWD) which showed to be significantly associated with ETEC (67%) followed by aEPEC (21.7%). On the contrary, aEPEC was more prevalent (60.3%) among diarrheas of suckling piglets, followed by ETEC (38.8%). STEC/ETEC or STEC were recovered in 11.3 and 0.9% of PWD and neonatal diarrhea, respectively. Detection of the F4 colonization factor was not significantly different between isolates recovered from neonatal pigs and those recovered post wean (40.5 versus 27.7%) while F18 was only present among PWD isolates (51.5% of ETEC, STEC, and STEC/ETEC isolates). We also found a high prevalence of resistance to colistin related to the presence of the mcr-1 gene (25.6% of the diarreagenic isolates). The characterization of 65 representative mcr-1 isolates showed that all were phenotypically resistant to colistin (>2 μg/ml), and most (61 of 65) multidrug-resistant (MDR). Six ETEC and one STEC mcr-1 isolates were also carriers of ESBL genes. In addition, other seven mcr-1 isolates harbored mcr-4 (three ETEC) and mcr-5 (two ETEC and two aEPEC) genes. In the phylogenetic analysis of the 65 mcr-1 diarrheagenic isolates we found that more than 50% (38 out of 65) belonged to A-ST10 Cplx and from those, 29 isolates showed the clonotype CH11-24. In this study, we also recovered 18 ST131 isolates including seven mcr-1 carriers. To the best of our knowledge, this would be the first report of ST131 mcr-1 isolation in pigs. Worryingly, the swine mcr-1 ST131 carriers also showed MDR, including to trimethoprim-sulfamethoxazole, tobramycin, gentamicin and ciprofloxacin. In the PFGE-macrorestriction comparison of clinical swine and human ST131, we found high similarities (≥85%) between two pig and two human ST131 isolates of virotype D5. Acquisition of mcr-1 by this specific clone means an increased risk due to its special feature of congregating virulence and resistance traits, together with its spread capability. Here we show a potential zoonotic swine source of ST131 This study was supported by projects AGL2016-79343-R from the Agencia Estatal de Investigación (AEI, Spain) and FEDER; PI16/01477 from Plan Estatal de I C D C I 2013–2016, Instituto de Salud Carlos III (ISCIII), Subdirección General de Evaluación y Fomento de la Investigación, and FEDER; CN2012/303 andED431C 2017/57 from the Consellería de Cultura, Educación e Ordenación Universitaria (Xunta de Galicia), and FEDER IG-M acknowledges the Conselleria de Cultura, Educación e Ordenación Universitaria, Xunta de Galicia for his grant (Ref. ED481A-2015/149) “Axudas de apoio á etapa predoutoral do Plan galego de investigación, innovación e crecemento 2011-2015 SI

This is a wide epidemiological study of 499 E. coli isolates recovered from 179 outbreaks of enteric colibacillosis from pig production farms in Spain during a period of 10 years. Most samples were of diarrheagenic cases occurred during the post-wean period (PWD) which showed to be significantly associated with ETEC (67%) followed by aEPEC (21.7%). On the contrary, aEPEC was more prevalent (60.3%) among diarrheas of suckling piglets, followed by ETEC (38.8%). STEC/ETEC or STEC were recovered in 11.3 and 0.9% of PWD and neonatal diarrhea, respectively. Detection of the F4 colonization factor was not significantly different between isolates recovered from neonatal pigs and those recovered post wean (40.5 versus 27.7%) while F18 was only present among PWD isolates (51.5% of ETEC, STEC, and STEC/ETEC isolates). We also found a high prevalence of resistance to colistin related to the presence of the mcr-1 gene (25.6% of the diarreagenic isolates). The characterization of 65 representative mcr-1 isolates showed that all were phenotypically resistant to colistin (>2 μg/ml), and most (61 of 65) multidrug-resistant (MDR). Six ETEC and one STEC mcr-1 isolates were also carriers of ESBL genes. In addition, other seven mcr-1 isolates harbored mcr-4 (three ETEC) and mcr-5 (two ETEC and two aEPEC) genes. In the phylogenetic analysis of the 65 mcr-1 diarrheagenic isolates we found that more than 50% (38 out of 65) belonged to A-ST10 Cplx and from those, 29 isolates showed the clonotype CH11-24. In this study, we also recovered 18 ST131 isolates including seven mcr-1 carriers. To the best of our knowledge, this would be the first report of ST131 mcr-1 isolation in pigs. Worryingly, the swine mcr-1 ST131 carriers also showed MDR, including to trimethoprim-sulfamethoxazole, tobramycin, gentamicin and ciprofloxacin. In the PFGE-macrorestriction comparison of clinical swine and human ST131, we found high similarities (≥85%) between two pig and two human ST131 isolates of virotype D5. Acquisition of mcr-1 by this specific clone means an increased risk due to its special feature of congregating virulence and resistance traits, together with its spread capability. Here we show a potential zoonotic swine source of ST131.

We investigate the physical properties of soap films and soap foams, the liquid phase of which contains a stable colloidal suspension of magnetic particles. The physical properties of such systems result from the equilibrium between the capillary forces, the gravity and the local magnetic forces. Therefore, they depend on the strength of an applied magnetic field or force, which makes it possible to act from outside on the system. We present the effect of the external field on the magnetic soap foams and films through two studies. First, we show that the dynamics of drainage in a freely suspended magnetic soap film is modified by an external magnetic field. Second, we present the control, via an external magnetic force, of the structure adopted by a monodisperse foam in a cylindrical tube. Those studies open possible applications of the ferrofluid foam, in the field of technological applications, but also as a model experimental system to study the drainage, the dynamical rheology, and the stability of soap foams.

We present here new experimental results about the waves at the horizontal free surface of a magnetic fluid submitted to a normal magnetic field. The waves are generated by a small modulation at frequency of the vertical field . Using a shadowgraph method, we are able to measure the wavevector k of the 2D waves for a given value of and . The dispersion relation of the surface waves is established experimentally. On the other hand, we propose a theoretical derivation of the dispersion equation which includes a more complete treatment of the magnetic term than the previous works. Finally, we conclude that a linear and inviscid analysis is sufficient to fit well the experimental data, except in the vicinity of the critical field where a surface instability occurs.

The evolution of a liquid foam usually mixes quasi-equilibrium topological and geometrical features in an intricate way. We take advantage of special properties of ferrofluid froths and of constrained area evolution simulations, to distinguish the effects of side swapping (TI processes) from other rearrangements in the froth. Cell elongation characterizes the froth and its deviation from mechanical equilibrium as robustly as the usually measured total wall length, that is surface energy.

Viscous fingering phenomenon in a linear channel is studied for a magnetic fluid subjected to an external magnetic field. The competition between the hydrodynamic effects and the capillary effects leads to the formation of an interface between the air and the fluid which has a finger shape. It is the so-called Saffman–Taylor instability (STI). The influence of the magnetic effects depends on the direction of the applied field: it is possible either to enhance or to reduce the destabilizing phenomena. We study the onset of the STI and compare the experimental results with the linear analysis including the magnetic contribution. In the nonlinear regime, the measurement of the width of the finger as a function of the direction and the amplitude of the magnetic field is understood using a phenomenological approach.

Two-dimensional magnetic fluid foams are cellular structures whose framework is made of magnetic fluid. The features of these equilibrated patterns are driven by a control parameter: the amplitude of the applied magnetic field. When the latter is rapidly increased, an instability occurs: the walls between cells undulate. Such an instability has also been observed in other 2D cellular structures, which exist for instance in Langmuir monolayers or in magnetic garnets thin films. In this paper we give a theoretical analysis of this instability, the issues of which are shown to be well confirmed by experiments and numerical simulations.

We present an experimental study of a cellular system which may be formed in a two-dimensional ~2D! layer made of an immiscible mixture of a magnetic fluid and an oil. We obtain a wet or a dry 2D froth, the characteristics of which are determined by the strength of an externally applied magnetic field. The froth is formed in an equilibrium state; the topological and geometrical features of the froth are fixed by the value of the applied field. The cellular pattern of the froth is stable in time, and a coarseninglike behavior is observed on decreasing the amplitude of the field. This cellular system can be used as a model to study topological processes in the equilibrium state, contrary to soap froths which are nonequilibrium systems because gas diffusion occurs. We show that the topological characteristics are statistically reversible after a magnetic-field cycle, and we present a statistical study of the froth features as a function of the amplitude of the field. The topological correlations between neighboring cells are well described by the Aboav-Weaire law. Finally, we consider the area of an n-sided cell, and show that its growth rate ~magnetic field dependent! is, in a surprising manner, proportional to n26, similarly to the Von Neumann law. @S1063-651X~97!10009-5#

We present some experimental results concerning the conformational instabilities observed in a thin layer made of an immiscible mixture of a magnetic fluid and another liquid submitted to an external magnetic field. We observed macroscopic domains with stripe or bubble shape. The transition bet~~een the two morphologies is observed and a coexistence of the two phases is visualized in a variable thickness layer. Furthermore, we give other results about the instabilities of the parallel stripe pattern: by increasing the external field the stripe pattern becomes a chevron structure, which also becomes unstable for higher values of the magnetic field and gives a hairpin pattern. Finally, we present a new system: a magnetic liquid froth in two dimensions which is analogous to soap froths with an additional external control parameter, the magnetic field.

Two methods of determination of the surface tension at the interface of a magnetic liquid and another fluid, in a confined two-dimensional geometry, are presented. The first is based upon a surface instability under the action of a vertical magnetic field and the second uses the deformation of a magnetic droplet in plane layer under the influence of a horizontal magnetic field. Theoretical calculations and experimental results are presented in both cases. Both determinations lead to comparable values of the surface tension $\ensuremath{\sigma}\ensuremath{\approx}3$ mN ${\mathrm{m}}^{\ensuremath{-}1}$.

An immiscible two-component mixture, made of a magnetic fluid and an organic liquid, in a Hele-Shaw cell under a magnetic field, can form different patterns like stripes or bubbles. Two-dimensional smectic-like structures are obtained with many parallel stripes. An analogy with a smectic liquid crystal allows us to define elastic moduli of the stripes. These are measured from very simple experiments. From stripe pattern energy calculation, the dependence of these elastic constants on control parameters is established. The main result is that the smectic analogy allows a rather good description of the stripe system.

We synthesise the results of different experiments concerning the structure of 2D crystalline phases and smectic phases in Langmuir films fully or partially made of dichroic amphiphiles. We develop an experimental procedure and the related theory to deduce the local order of absorption dipoles from measurements of the light intensity reflected by the film. Together with conventional techniques, this procedure is applied to determine the crystalline structure in films made of pure dyes. The phase diagram of a binary mixture, showing several mesophases, is also explored as a function of the film composition. The same optical technique is used to measure the mean square amplitude of the fluctuations of the dipolar order parameter. We infer the elastic constant K associated to the dipolar order in the mixed film, close to the smectic/isotropic transition. K decreases when approaching the isotropic phase, and jumps to zero at the transition, in agreement with the Kosterlitz-Thouless prediction.

We report the first phase diagram of a Langmuir film at the air-formamide inter- face. Stable films of phospholipids such as DPPC or DSPC undergo phase transitions observed on isotherms or by fluorescence microscopy. They display bidimensional gas, liquid and solid phases, as well as two mesophases, the latter coexist with liquid on a sharp first-order transition plateau. We compare these observations with known results on films on water.

Grazing incidence X-ray diffraction is performed on a Langmuir monolayer made of pure fluorescent NBD-stearic acid, spread at the free surface of water. It shows several intense narrow peaks in the solid phase, at the same wavevectors as the brightest peaks observed earlier by electron diffraction, for a monolayer transferred onto an amorphous polymer substrate. Thus the solid phase has the same crystalline structure on water and on solid substrate. The relative peak intensities are comparable in both experiments, and in the proposed model for the molecular structure. This model also accounts for the very large anisotropy of the crystalline phase and its optical properties. This phase could be ferroelectric, as previously assumed in order to explain the elongated shape of the crystals

In a Langmuir monolayer made of pure fluorescent NBD stearic acid, an ordered anisotropic phase was observed. The molecular structure of this solid phase was determined by electron scattering after transfer of the layer onto a solid substrate by the usual Langmuir-Blodgett technique. The electron diffraction pattern shows sharp peaks, indicating two-dimensional long-range positional order. The diffraction pattern is analyzed by comparison with Fourier transforms of models of molecular arrangements. The simulations reveal that the aliphatic chains are positioned along parallel strips, in agreement with optical studies.

A film of amphiphilic carbocyanine dye is spread on water and observed by fluorescence and polarized light techniques. With ClO4− counterions in the subphase, a first order transition occurs between an isotropic liquid phase and a solid one, made of birefringent elongated domains. On pure or acidified water, this transition takes place at a higher surface pressure, close to the monolayer collapse. When the carbocyanine is mixed with a fraction x of stearic acid another condensed phase appears, made of birefringent disks growing around a central disinclination. We report data concerning the phase diagram, and present a photometric method to measure the film thickness. We also discuss the nature of the different phases, and the possibility of a smectic-to-isotropic transition at x = 0.6.

A model and numerical code are presented that describe quasi-one-dimensional compressible flows of gases with nonequilibrium of their vibrational and electronic energy modes. Chemical reaction channels are also modeled. Rate equations governing individual vibrational state populations are integrated as a function of streamwise position in a flow channel. Results are presented for flows of CO, N 2 , and NO in supersonic nozzles, and the conditions creating extreme nonequilibrium overpopulation of upper vibrational states are shown

International audience; This study of social representations aims at identifying the process involved in the responses produced with a substitution technique. Two alternative hypotheses are discussed: one that considers that substitution induces social comparison (Chokier and Moliner, 2006), the other suggesting that this technique leads to a reduction of normative pressures (Guimelli, 1998). In the research presented here, we studied the social representations of Drug addicts (in the tolerance towards the use of cannabis) and of Unemployed people, in order to compare the results with those obtained by Chokier and Moliner (2006) about security. With a specific population of students, these objects allowed us to manipulate two levels of distance to the object of representation. Concerning the technique of substitution, three levels of distance to the reference group (French people in general, Young people, Students) were combined into questionnaires with four types of instructions: standard, substitution, pro- and counter-normative. The PCA highlights a Guttman effect, which indicating that the responses produced with standard instruction are less normative than the responses produced with the substitution instruction to Young people. These results invalidate an explanation in terms of effect Primus Inter Pares. Globally, the results mainly show that the more the distance to the object is low and the distance to the reference group is high, the more the responses produce in substitution are seen as pro-normative and near from those produced with standard instruction. More specifically, we identified a number of inconsistencies with regard to what one could expect from an explanation of the phenomena in terms of personal versus social identity. As regards the representation of Unemployed people, the more the participants are closed to the reference group, the more the responses produced with an instruction of auto-valorization (pro-normative) are closed to those produced in substitution. However, on one hand, this result is observed only with the representation of Unemployed people, and, on the other hand, a social comparison explanation would suppose that the participants perceived the group of French people in general as homogeneous and identified themselves to this group at the same level than to the two other reference groups, which is unlikely. Finally, these results lead us to conclude that the substitution does not induce social comparison (Chokier and Moliner, 2006), but more probably reduction of normative pressures (Guimelli, 1998). It thus suggests that the study of masking effects through a substitution technique should take into account two parameters: distance to the object and distance to the reference group.; Cette étude de représentations sociales permet d’identifier le processus impliqué dans les réponses produites avec une technique de substitution. Deux hypothèses alternatives sont discutées : l’une considère que la substitution induit un processus de comparaison sociale (Chokier et Moliner, 2006), l’autre suggère que cette technique entraîne une réduction des pressions normatives (Guimelli, 1998). Dans la recherche présentée ici, on étudiait les représentations sociales du Toxicomane (ici la tolérance vis-à-vis de la consommation de cannabis) et du Chômeur afin de comparer les résultats obtenus à ceux qu’obtiennent Chokier et Moliner (2006) à propos de la Sécurité. Avec une population spécifique, des Étudiants, ces objets permettent de manipuler deux niveaux de distance à l’objet de représentation. Concernant la technique de substitution, trois niveaux de distance au groupe de référence (Français en général, Jeunes, Étudiants) ont été combinés dans des questionnaires avec quatre types de consignes : standard, substitution, pro- et contre-normatives. L’ACP met en évidence un effet Guttman indiquant que les réponses en consigne standard sont moins normatives que les réponses produites en substitution aux Jeunes. On écarte ainsi une explication en termes d’effet Primus Inter Pares (PIP). De façon générale, les résultats montrent, principalement, que plus la distance à l’objet est faible et la distance au groupe de référence élevée, plus les réponses en substitution sont vues comme pro-normatives et proches des réponses standard. Le détail des résultats met quant à lui en évidence un certain nombre d’incohérences en regard de ce que l’on pourrait attendre d’une explication des phénomènes en termes d’identité sociale versus personnelle. Concernant la représentation du Chômeur, les réponses produites en consigne d’autovalorisation et celles produites en substitution sont d’autant plus proches que les groupes de références sont proches des participants, et cela quels que soient ces groupes de références. Toutefois, on constate, d’une part, que ce résultat ne s’observe qu’avec la représentation du Chômeur, et, d’autre part, qu’il faudrait alors conclure que les participants perçoivent le groupe des Français en général comme homogène et s’identifient à ce dernier au même degré qu’au deux autres groupes de référence. Finalement, ces résultats amènent à conclure que la consigne de substitution n’induit pas un processus de comparaison sociale (Chokier et Moliner, 2006), mais plus sûrement un processus de réduction des pressions normatives (Guimelli, 1998). On suggère ainsi que l’étude des effets de masquage par le biais d’une technique de substitution doit avoir pour préalable la prise en compte des deux paramètres que sont la distance à l’objet et la distance au groupe de référence.

Dynamics of the chemical reaction model introduced by Fichthorn et al (1989) is discussed along the lines of the authors previous work. They find that the steady-state reaction rate is reached as 1/t in Euclidean dimension d=1 and d=2 is the marginal dimension. The distinction made between the segregation regime and the saturation regime is recovered for the transient regime.

We define the boundary energy for a 2D homogeneous phase in the general case of 1/Rn interactions between particles. In the large-domain size-limit, this energy is proportional to the interface length only for n > 3. For n ≤ 3 a line tension can no longer be defined. For arbitrary n, we calculate the mean amplitude of the thermal fluctuations of the boundary. A crystal interface is modelized by a periodic pinning potential U, and its roughness depends on the value of U averaged over boundary fluctuations. A first-order calculation shows that the interface is rough for n > 2, and faceted for n < 2, at any temperature. In the particular case n = 2 a roughening transition should occur at a finite temperature TR that we explicitly calculate. The possible observation of this transition in some experimental situations is discussed.

Recent experiments and analyses involving vibration-to-vibration (VV) pumped carbon monoxide are presented. Pure CO, and COAr mixtures, in a flowing-gas cell, are vibrationally excited by absorption of CO laser radiation. The pump laser is a slow-flow liquid-nitrogen wall-cooled device, which can be operated in either Q -switched or cw mode for these experiments. There is output down to the v =1−0 vibrational transition ( Q -switched) or v =2−1 (cw). CO has been VV pumped in these experiments to very high vibrational quantum levels, at partial pressures up to 65 Torr. The rotational/translational mode temperature has been measured by emission spectroscopy of rotationally resolved Swan bands of C 2 formed from reaction of the VV pumped CO. Measured rotational mode temperatures up to 1500 K have been achieved with strong VV pumping. Low levels of ionization have been observed under these extreme pumping conditions. Results of time-resolved experiments exploring the kinetics are presented. These results are analyzed using a time-dependent kinetic master equation modeling code for the vibrational state kinetics.

Patterns of magnetic fluid stripes are experimentally studied and compared to numerical simulations by boundary integral equation technique. Like in amphiphile monolayers and ferromagnetic films, we observe bending and alternated fingering of a single stripe. For bending deformations, a two-dimensional-smectic analogy is presented. This analogy is only valid for quasistatic variations of the external magnetic field strength. A fingering phenomenon occurs for non-quasistatic variations of the fields and for large stripes.

This paper presents a trellis coded 8PSK transmitter equipment designed for space applications. It enables high data rate transmission for Earth observation satellites. The equipment is based on channel coding functions implemented in FPGA circuits, a MMIC medium level RF chain, including a MMIC direct 8PSK modulator, an Hybrid 6 W output amplifier and features a direct X band Local Oscillator (LO). Data rates up to 4 × 155.5 Mbps can be achieved. Design description and Engineering Model performances are provided in this paper.

We study the equilibrium energies of two-dimensional (2D) noncoarsening fluid foams, which consist of bubbles with fixed areas. The equilibrium states correspond to local minima of the total perimeter. We present a theoretical derivation of energy minima; experiments with ferrofluid foams, which can be either highly distorted, locally relaxed, or globally annealed; and Monte Carlo simulations using the extended large-Q Potts model. For a dry foam with small size variance we develop physical insight and an electrostatic analogy, which enables us to (i) find an approximate value of the global minimum perimeter, accounting for (small) area disorder, the topological distribution, and physical boundary conditions; (ii) conjecture the corresponding pattern and topology: small bubbles sort inward and large bubbles sort outward, topological charges of the same signs "repel" while charges of the opposite signs "attract;" (iii) define local and global markers to determine directly from an image how far a foam is from its ground state; (iv) conjecture that, in a local perimeter minimum at prescribed topology, the pressure distribution and thus the edge curvature are unique. Some results also apply to 3D foams.

We present experiments showing the Rayleigh-Taylor instability at the interface between a dense magnetic liquid and an immiscible less dense liquid. The liquids are confined in a Hele-Shaw cell and a magnetic field is applied perpendicular to the cell. We measure the wavelength and the growth rate at the onset of the instability as a function of the external magnetic field. The wavelength decreases as the field increases. The amplitude of the interface deformation grows exponentially with time in the early stage, and the growth rate is an increasing function of the field. These results are compared to theoretical predictions given in the framework of linear stability analysis.

International audience; We describe the concept of a voltage generator based on the use of a magnetic fluid. A cell contains two immiscible liquids: the lower liquid boils at a low temperature and the upper is a magnetic liquid magnetized by a permanent magnet. By heating the bottom of the cell the lower liquid boils, and bubbles of the gas phase cross both liquid phases; consequently a flux variation is induced in a detection coil. Finally, the gas phase condenses in a recovery device in order to be injected back at the bottom of the cell. We obtain a voltage generator with a shape signal linked to the nucleation frequency and volume of the gas bubbles. This device has been built by secondary school pupils and requires the acquisition of knowledge of magnetism, hydrodynamics and thermodynamics.

International audience; We describe the concept of a voltage generator based on the use of a magnetic fluid. A cell contains two immiscible liquids: the lower liquid boils at a low temperature and the upper is a magnetic liquid magnetized by a permanent magnet. By heating the bottom of the cell the lower liquid boils and bubbles of the gas phase cross both liquid phases; consequently a flux variation is induced in a detection coil. Finally, the gas phase condenses in a recovery device in order to be injected back at the bottom of the cell. We obtain a voltage generator with a shape signal linked to the nucleation frequency and to the volume of the gas bubbles.

We present a new cellular structure, obtained in a pseudo two-dimensional (2D) layer of magnetic fluid (MF) submitted to a perpendicular magnetic field. This froth is analogous to 2D soap froths, because its energy contains an interfacial contribution. Nevertheless, whereas a soap froth coarsens in time to minimize the surface of its interface, the 2D MF froth can be stable in time. Indeed it also has a magnetic energy, which allows the cellular pattern to reach an equilibrium state. The properties of such a froth in its equilibrium state are thus driven by competition between the surface energy and the magnetic energy. The latter depends on the amplitude of the applied magnetic field, which is a control parameter of this system. An evolution of the structure is obtained on decreasing the amplitude of the field: the number of cells decreases so that the pattern turns into a single drop of MF in zero field. We present here a study of this coarsening with decreasing of the field. For high amplitudes of the applied field, we have observed out of equilibrium states of the 2D MF froth: the area of the cells evolves in time, depending on their number of sides. This behaviour looks like a Von Neumann one (which drives the time-evolution of 2D soap froths), but with the opposite sign: 5-sided cells grow in time, 7-sided cells shrink, whereas 6-sided cells do not evolve. In section 6, the 2D MF froths are shown to obey the Aboav and Weaire law which describes the topological interactions between cells, as all the 2D cellular structures. Finally, we present a potential application of the 2D MF froth, for the study of topology in 2D cellular patterns.

In the present work, to analyze the heterogeneity of the tumor-specific cytotoxic immune response, a large number of T cell clones were generated from the infiltrate of a tumor-proximal invaded lymph node, and two kinds of melanoma-specific CD8+ CTL clones were derived. The majority of T cell clones (about a hundred) are characterized by a specific lysis of the autologous tumor cell lines. Among 34 of the latter clones, HLA-A2 molecule and MART-1(27-35) peptide have been shown to play a predominant role in tumor recognition. However, no significant amplification at the tumor site was observed for 3 of these CTL. The other kind of tumor-specific CTL (1 oligoclonal and 2 clonal cell lines) did not lyse the autologous melanoma cell lines but lysed the "fresh" autologous tumor cells in a MHC class I-dependent manner. Functional analysis of the two different CTL clones have shown that they did not lyse NK targets, autologous peripheral monocytes, activated T cells, and transformed B cells or any of the few allogeneic cultured and uncultured melanoma cells we tested. TCR repertoire analysis has shown that one of these CTL clones was significantly detectable "in situ" among tumor-infiltrating lymphocytes, while not detectable among PBMC. Such melanoma-specific lymphocytes, which could not have been picked out through conventional screening procedures using tumor cell lines, could potentially play a role in tumor rejection. These results suggest that the immune response analyzed toward melanoma cell lines does not totally reflect the in situ immune status.

We have analyzed the human gamma/delta T cell alloreactive response to class II HLA-DR molecules and attempted to compare this response with that mediated by the TCR-alpha/beta counterparts. Several gamma/delta CTL clones from a healthy individual were generated in mixed lymphocyte reactions against an EBV-transformed B cell line termed E418. Fine specificity and primary TCR structure of 10 representative clones (all CD4- CD8 +/-) were then determined. Functional studies, with the use of B cell lines homozygous for HLA-DR (DR1-10), indicated that all gamma/delta T cell clones specifically reacted with HLA-DR2 molecules. In addition, five clones were able to cross-react with subtypes of HLA-DR8. Extended panel target experiments, including lymphoblastoid cells expressing various HLA-DR2 subtypes, showed that the T cell clones displayed distinct fine specificities. Clones with broad (Dw2, Dw12, Dw21, Dw8.1, and Dw8.2) or in contrast, more restricted (DRB1*1501 or DRB1*1503) specificity were identified. Furthermore, amino acid substitutions at predicted peptide binding site position 30 and TCR-interacting position 67 of the DRB*1 beta-chain seemed to affect alloresponse of some T cell clones. With respect to TCR-gamma/delta structure, diversity in gene segment usage was observed, with the predominance of T cells using a V3-J gamma 2/V1-J delta 1+ receptor. A smaller fraction of the cells expressed TCR comprising V gamma 9 and V delta 1 regions. In contrast, the V delta 3 gene segment was used by a minority of the cells, and the V delta 2 was not expressed by any T cell clone. Together, the present data indicate that similarly to TCR-alpha/beta, human TCR-gamma/delta lymphocytes may recognize in a highly specific fashion a particular HLA-DR heterodimer. T cell clones cross-reacting with other HLA-DR molecules were also identified. Despite some degree of heterogeneity, V gene segment use by alloreactive clones seemed to be nonrandom. No obvious correlation between TCR gene use and HLA-DR alloreactivity could be identified. Moreover, our results suggest that similarly to TCR-alpha/beta cells, foreign MHC-bound peptides may contribute to TCR-gamma/delta alloreactive response.

Institutionalized aged subjects, considered free of evolutive disease and whose body weight was stable, were studied. They were divided into two groups depending on their body mass index: controls (BMI greater than or equal to 24) and depleted (BMI less than or equal to 21). The depleted group, as judged by anthropometric measurements, showed dramatically reduced body muscle and adipose masses. Usual blood parameters were normal in both groups. Biochemical markers of the protein and energy status, viz. albumin, transthyretin, transferrin, somatomedin-C, as well as serum levels of osteocalcin and apolipoproteins AI, AII, B, CII, CIII and E, were not affected in the depleted group. However, moderate iron deficiency and marked zinc deficiency were found in this group. It is concluded that in the elderly, biochemical markers of the protein and energy status are not related to the nutritional status assessed by anthropometry.

A fully coupled implicit finite volume mctbod for dculr t ing rxisymmetric viscous flows with thermal and chemical noaequilibrium is presented. The numerid approximuion of the governing equations is &rived using a d order upwind schcme of H8rta1-Yee type for the inviscid fluxes and 8 sp.ce a n t e d s c h a ~ ~ ~ for thc viscous fluxes. Numerical fluxes and soume terms are fully coupled in the implicit scep. A particular attention is paid on the physical models involved in this study. New vansport models for species diffusion and thermal coaductivities for internal mode rre introduced. Furtbcmore, lo original dissociation-vibration coupling derived from Park's apprruch and including the influence of rcaaion rates on vibrational reluation is proposed. Results are first presented for a 2D uisymmetric thermo-chemical nonequilibrium flow around a rpberecylinder. Tbe influence of physical models is discussed. Comparisons ut performed with available numerical rcsults md show r rather good agreement. ' h e stcbad appliruion deals with tbe 2D uisymmetric flow around a hyperboloid simulating a shuttle shape in r hypemthalpic nozzle flow.

The equations governing chemical and vibrational non-equilibrium nozzle flows are first presented. The resulting differential system is then discretized using a fully implicit non centered finite volume approach. The method is finally applied to two different hypersonic nozzle geometries. Results are compared with equilibrium as well as with previous space marching calculations.

1. Four groups of rats were fed for 49 d on one of four semi-purified diets, without added cholesterol and containing 230 g/kg of the following isolated proteins: casein, whey, soya-bean or sunflower.2. Whey, soya-bean and sunflower proteins, when compared with casein, decreased the level of serum high-density-lipoprotein (HDL)-cholesterol. These low cholesterol levels were accompanied by an increase in the daily faecal excretion of neutral sterols and bile acids in the case of soya-bean protein, and by a decrease in the liver cholesterol content, when rats were fed on whey protein.3. Considering the amino acid composition of the four purified proteins, we observed that serum total and HDL-cholesterol levels had a significant positive correlation with tyrosine and glutamic acid, and a negative correlation with cystine and alanine.4. The present study showed that the hypocholesterolaemic effect of dietary proteins was not related to their animal or vegetable origin.