Improved ion acceleration via laser surface plasma waves excitation

International audienceThe possibility of enhancing the emission of the ions accelerated in the interaction of a high intensity ultra-short (<100 fs) laser pulse with a thin target (<10 l0), via surface plasma wave excitation is investigated. Two-dimensional particle-in-cell simulations are performed for laser intensities rangingfrom 10^19 to 10^20 W/cm2.µm2. The surface wave is resonantly excited by the laser via the coupling with a modulation at the target surface. In the cases where the surface wave is excited, we find anenhancement of the maximum ion energy of a factor ~2 compared to the cases where the targetsurface is flat

Particle-in-cell modelling of relativistic laser-plasma interaction with the adjustable damping, direct implicit method

Implicit particle-in-cell codes offer advantages over their explicit counterparts in that they suffer weaker stability constraints on the need to resolve the higher frequency modes of the system. This feature may prove particularly valuable for modeling the interaction of high-intensity laser pulses with overcritical plasmas, in the case where the electrostatic modes in the denser regions are of negligible influence on the physical processes under study. To this goal, we have developed the new two-dimensional electromagnetic code ELIXIRS (standing for ELectromagnetic Implicit X-dimensional Iterative Relativistic Solver) based on the relativistic extension of the so-called Direct Implicit Method [D. Hewett and A. B. Langdon, J. Comp. Phys. \textbf{72}, 121(1987)]. Dissipation-free propagation of light waves into vacuum is achieved by an adjustable-damping electromagnetic solver. In the high-density case where the Debye length is not resolved, satisfactory energy conservation is ensured by the use of high-order weight factors. In this paper, we first present an original derivation of the electromagnetic direct implicit method within a Newton iterative scheme. Its linear properties are then investigated through numerically solving the relation dispersions obtained for both light and plasma waves, accounting for finite space and time steps. Finally, our code is successfully benchmarked against explicit particle-in-cell simulations for two kinds of physical problems: plasma expansion into vacuum and relativistic laser-plasma interaction. In both cases, we will demonstrate the robustness of the implicit solver for crude discretizations, as well as the gains in efficiency which can be realized over standard explicit simulations

Glial activation in white matter following ischemia in the neonatal P7 rat brain

This study examines cell death and proliferation in the white matter after neonatal stroke. In post-natal day 7 injured rat, there was a marked reduction in myelin basic protein (MBP) immunostaining mainly corresponding to numerous pyknotic immature oligodendrocytes and TUNEL-positive astrocytes in the ipsilateral external capsule. In contrast, a substantial restoration of MBP, as indicated by the MBP ratio of left-toright, occurred in the cingulum at 48 (1.27 +- 0.12) and 72 (1.30 +- 0.18, p<0.05) hours of recovery as compared to age-matched controls (1.03 +- 0.14). Ki-67 immunostaining revealed a first peak of newly-generated cells in the dorsolateral hippocampal subventricular zone and cingulum at 72 hours after reperfusion. Double immunofluorescence revealed that most of the Ki-67-positive cells were astrocytes at 48 hours and NG2 pre-oligodendrocytes at 72 hours of recovery. Microglia infiltration occurs over several days in the cingulum and a huge quantity of macrophages reached the subcortical white matter where they engulfed immature oligodendrocytes. The overall results suggest that the persistent activation of microglia involves a chronic component of immunoinflammation, which overwhelms repair processes and contributes to cystic growth in the developing brain.Comment: 30 page

Efficient laser-overdense plasma coupling via surface plasma waves and steady magnetic field generation

International audienceThe efficiency of laser overdense plasma coupling via surface plasma wave excitation is investigated. Two-dimensional particle-in-cell simulations are performed over a wide range of laser pulse intensity from 10 15 to 10 20 W cm À2 lm 2 with electron density ranging from 25 to 100n c to describe the laser interaction with a grating target where a surface plasma wave excitation condition is fulfilled. The numerical studies confirm an efficient coupling with an enhancement of the laser absorption up to 75%. The simulations also show the presence of a localized, quasi-static magnetic field at the plasma surface. Two interaction regimes are identified for low (Ik 2 10 17 W cm À2 lm 2) laser pulse intensities. At " relativistic " laser intensity, steady magnetic fields as high as $580 MG lm/k 0 at 7 Â 10 19 W cm À2 lm 2 are obtained in the simulations

Emballages sans frontières

Image d’ouverture Enfant absorbant un sachet d’ATPE. © Jean-François Carémel Les techniques de conservation alimentaire permettent l’allongement de la durée de vie des produits, leur mobilité spatiale, et contribuent à l’émergence de nouveaux usages… Dans le contexte des urgences humanitaires, marquées par la nécessité d’immédiateté des réponses, ces mobilités dans le temps, l’espace et les usages peuvent se révéler cruciales. C’est ce qu’illustre la trajectoire des Aliments Thérapeutiques P..

Emballages sans frontières

Cette contribution explore les enjeux de la conservation des aliments thérapeutiques prêts à l’emploi (ATPE). Objets frontières à la fois aliment et médicament, ces produits principalement distribués par les acteurs de la médecine d’urgence ont transformé la prise en charge de la malnutrition aiguë de l’enfant, en la sortant de l’hôpital pour la confier à l’entourage familial. Leur mobilité dans les temps et dans les espaces d’exception de l’aide, comme leur diffusion globale, peut s’expliquer par leurs propriétés sociotechniques.À partir d’une anthropologie « multisites » qui s’intéresse aux fonctions de leurs emballages, nous suivons les ATPE : des usines de production en France et en Afrique de l’Ouest jusque dans les concessions familiales au Niger, des hôpitaux de la médecine humanitaire aux boutiquiers dans les villages, des prescriptions des agents de santé aux corps des patients. Ce déplacement de l’analyse conduit à considérer l’emboîtement des conditionnements (l’articulation d’un « emballage lipidique », par l’enrobement dans une pellicule grasse des complexes minéro-vitaminiques, et d’un emballage physique dont les formes ont évolué dans le temps), et à prendre en compte la stabilisation des procédés industriels et de transfert de technologies. L’emballage est étudié comme une frontière (technique, humanitaire, logistique), mais aussi comme un espace de négociations.Une perspective diachronique revenant sur les solutions techniques aux défaillances initiales de l’emballage des ATPE permet d’en souligner les différents enjeux en termes de conservation : une forte mobilité, un délai d’utilisation long quelles que soient les conditions climatiques et de transport, une facilité de manipulation, de distribution et d’administration de masse… Ce conditionnement du produit oriente ses usages et dessine en creux les contextes de crise et les systèmes de santé défaillants pour lesquels il est pensé. Le succès du produit repose, via son conditionnement, sur sa capacité d’exclusion de son environnement, et en même temps sur ses réappropriations multiples par celui-ci. Ces éléments invitent à prendre en compte la fluidité de la matérialité dans l’analyse des « modèles voyageurs ».This paper considers challenges on the conservation of Ready to Use Therapeutic Food (RUTF), which places itself between food and medicine. RUTFs are used as a treatment for malnutrition, during civil crisis or starvation (famine). RUTFs are thus mainly distributed in contexts of urgency. The crucial issue of its right conservation reveals the importance on the choice of its packaging both on the technical and symbolic fronts. The analysis is from a ‘multi-sites’ anthropological perspective, covering from French factory to local factories of family concessions in West Africa, to health rehabilitation centers, to international markets, to local villages shopkeepers. This product being a peanut paste base is conserved in a double layered sachet : the lipid in the product, helps to coat and protect the mineral-vitamin complex in a fatty film, thanks to specific manufacturing processes. The physical nature of the sachet has evolved with time and field experiences. The progressively standardized flexible packaging can therefore be studied as a frontier englobing technical, humanitarian, logistic, and as a negotiating space… A diachronic perspective, underlying technical solutions to the initial failures of the packaging highlights the different criteria at stake : high mobility, long shel-life, local climatic and transport conditions, easy usage and massive distribution, the function of treatment and use of detection and diagnostis by appetite of children. The packaging of the product is orientating its usage, but also draws in hollow the crisis context and the failing health care system for which it has been conceived… The success of the product depends, through its packaging and its ability to exclude and conserve itself from the outer environment, which is the basis of the “traveling models”

EVALUATION de l'IMPACT d'un PROGRAMME d'ÉDUCATION THÉRAPEUTIQUE dans la SCHIZOPHRENIE

International audienceSchizophrenia affects 1% of the population. It greatly alters the quality of life of patients and their autonomy. In this study, we evaluated the effect of a psychoeducation program (PEP) in 17 patients.The effectiveness of the program was measured with validated psychometric questionnaires assessing functional remission, quality of life, adherence to drug treatments and satisfaction.The results revealed a significant effect of PEP on functional remission and adherence to treatment, but no effect on the overall quality of life score. Self-esteem and autonomy were improved. No patient presented evidence for a major depressive episode after PEP. Patients were generally very satisfied of the program.In conclusion, PEP has a beneficial effect on coping strategies of patients with schizophrenia. Awareness of the deleterious effects of the disease at the family, social, emotional and somatic levels allows patients to be challenged with active involvement in care. Building self-esteem ("I'm not crazy, I have an illness") helps patients to be more easily engaged with caregivers.Integrating PEP into the overall care of the patient as a pivotal care (drug treatment, psychosocial rehabilitation, family therapy) is very beneficial. A regular assessment with reinforcement of the knowledge and requests of the patient will be able to improve the overall quality of life score.La schizophrénie affecte 1% de la population. Elle altère grandement la qualité de vie des patients et leur autonomie. Dans cette étude, nous avons évalué l’effet d’un programme d’éducation thérapeutique (ETP) réalisée en groupe, chez 17 patients suivis en psychiatrie et stabilisés. L’efficacité du programme a été mesurée à partir de questionnaires psychométriques validés évaluant la rémission fonctionnelle, la qualité de vie des patients, leur adhésion aux traitements médicamenteux et leur satisfaction quant aux soins reçus.Les résultats révèlent un effet significatif de l’ETP sur la rémission fonctionnelle et l’adhésion aux traitements, mais pas d’effet sur le score global de qualité de vie. L’estime de soi et l’autonomie sont améliorées. Aucun patient n’a présenté de signes en faveur d’un épisode dépressif majeur après l’ETP. Les patients sont globalement très satisfaits du programme.En conclusion, l’ETP a un effet bénéfique sur les stratégies d’adaptation des patients qui souffrent de schizophrénie. La prise de conscience des effets délétères de la maladie au niveau familial, social, affectif et somatique permet aux patients une remise en question avec une implication active dans les soins. Le renforcement de l’estime de soi (« je ne suis pas fou, j’ai une maladie ») aide les patients à se livrer plus facilement auprès des soignants.Intégrer l’ETP dans la prise en charge globale du patient comme pivot dans l’articulation des soins (traitements médicamenteux, réhabilitation psychosociale, thérapie familiale) est très bénéfique. Un bilan régulier avec renforcement des connaissances et demandes du patient pourra améliorer le score global qualité de vie

Complex nature of apparently balanced chromosomal rearrangements in patients with autism spectrum disorder

Background: Apparently balanced chromosomal rearrangements can be associated with an abnormal phenotype, including intellectual disability and autism spectrum disorder (ASD). Genome-wide microarrays reveal cryptic genomic imbalances, related or not to the breakpoints, in 25% to 50% of patients with an abnormal phenotype carrying a microscopically balanced chromosomal rearrangement. Here we performed microarray analysis of 18 patients with ASD carrying balanced chromosomal abnormalities to identify submicroscopic imbalances implicated in abnormal neurodevelopment. Methods: Eighteen patients with ASD carrying apparently balanced chromosomal abnormalities were screened using single nucleotide polymorphism (SNP) arrays. Nine rearrangements were de novo, seven inherited, and two of unknown inheritance. Genomic imbalances were confirmed by fluorescence in situ hybridization and quantitative PCR. Results: We detected clinically significant de novo copy number variants in four patients (22%), including three with de novo rearrangements and one with an inherited abnormality. The sizes ranged from 3.3 to 4.9 Mb; three were related to the breakpoint regions and one occurred elsewhere. We report a patient with a duplication of the Wolf-Hirschhorn syndrome critical region, contributing to the delineation of this rare genomic disorder. The patient has a chromosome 4p inverted duplication deletion, with a 0.5 Mb deletion of terminal 4p and a 4.2 Mb duplication of 4p16.2p16.3. The other cases included an apparently balanced de novo translocation t(5;18)(q12;p11.2) with a 4.2 Mb deletion at the 18p breakpoint, a subject with de novo pericentric inversion inv(11)(p14q23.2) in whom the array revealed a de novo 4.9 Mb deletion in 7q21.3q22.1, and a patient with a maternal inv(2)(q14.2q37.3) with a de novo 3.3 Mb terminal 2q deletion and a 4.2 Mb duplication at the proximal breakpoint. In addition, we identified a rare de novo deletion of unknown significance on a chromosome unrelated to the initial rearrangement, disrupting a single gene, RFX3. Conclusions: These findings underscore the utility of SNP arrays for investigating apparently balanced chromosomal abnormalities in subjects with ASD or related neurodevelopmental disorders in both clinical and research settings

Finger creases lend a hand in Kabuki syndrome.

International audienceKabuki syndrome (KS) is a rare syndrome associating malformations with intellectual deficiency and numerous visceral, orthopedic, endocrinological, immune and autoimmune complications. The early establishment of a diagnostic of KS leads to better care of the patients and therefore prevents complications such as perception deafness, severe complications of auto-immune diseases or obesity. However, the diagnosis of KS remains difficult because based on the appreciation of facial features combined with other highly variable features. We describe a novel sign, namely the attenuation and/or congenital absence of the IPD crease of the third and fourth fingers associated with limitation of flexion of the corresponding joints, which seems to be specific of KS and could help the clinician to diagnose KS

The phenotype of floating-harbor syndrome:clinical characterization of 52 individuals with mutations in exon 34 of SRCAP

Background\ud Floating-Harbor syndrome (FHS) is a rare condition characterized by short stature, delays in expressive language, and a distinctive facial appearance. Recently, heterozygous truncating mutations in SRCAP were determined to be disease-causing. With the availability of a DNA based confirmatory test, we set forth to define the clinical features of this syndrome.\ud \ud Methods and results\ud Clinical information on fifty-two individuals with SRCAP mutations was collected using standardized questionnaires. Twenty-four males and twenty-eight females were studied with ages ranging from 2 to 52 years. The facial phenotype and expressive language impairments were defining features within the group. Height measurements were typically between minus two and minus four standard deviations, with occipitofrontal circumferences usually within the average range. Thirty-three of the subjects (63%) had at least one major anomaly requiring medical intervention. We did not observe any specific phenotype-genotype correlations.\ud \ud Conclusions\ud This large cohort of individuals with molecularly confirmed FHS has allowed us to better delineate the clinical features of this rare but classic genetic syndrome, thereby facilitating the development of management protocols.The authors would like to thank the families for their cooperation and permission to publish these findings. SdM would like to thank Barto Otten. Funding was provided by the Government of Canada through Genome Canada, the Canadian Institutes of Health Research (CIHR) and the Ontario Genomics Institute (OGI-049), by Genome Québec and Genome British Columbia, and the Manton Center for Orphan Disease Research at Children’s Hospital Boston. KMB is supported by a Clinical Investigatorship Award from the CIHR Institute of Genetics. AD is supported by NIH grant K23HD073351. BBAdV and HGB were financially supported by the AnEUploidy project (LSHG-CT-2006-37627). This work was selected for study by the FORGE Canada Steering Committee, which consists of K. Boycott (University of Ottawa), J. Friedman (University of British Columbia), J. Michaud (University of Montreal), F. Bernier (University of Calgary), M. Brudno (University of Toronto), B. Fernandez (Memorial University), B. Knoppers (McGill University), M. Samuels (Université de Montréal), and S. Scherer (University of Toronto). We thank the Galliera Genetic Bank - “Telethon Genetic Biobank Network” supported by Italian Telethon grants (project no. GTB07001) for providing us with specimens