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International audience; Purpose: A European network was initiated in 2012 by 23 partners from 16 European countries with the aim to significantly increase individualized dose reconstruction in case of large-scale radiological emergency scenarios. Results: The network was built on three complementary pillars: (1) an operational basis with seven biological and physical dosimetric assays in ready-to-use mode, (2) a basis for education, training and quality assurance, and (3) a basis for further network development regarding new techniques and members. Techniques for individual dose estimation based on biological samples and/or inert personalized devices as mobile phones or smart phones were optimized to support rapid categorization of many potential victims according to the received dose to the blood or personal devices. Communication and cross-border collaboration were also standardized. To assure long-term sustainability of the network, cooperation with national and international emergency preparedness organizations was initiated and links to radiation protection and research platforms have been developed. A legal framework, based on a Memorandum of Understanding, was established and signed by 27 organizations by the end of 2015. Conclusions: RENEB is a European Network of biological and physical-retrospective dosimetry, with the capacity and capability to perform large-scale rapid individualized dose estimation. Specialized to handle large numbers of samples, RENEB is able to contribute to radiological emergency preparedness and wider large-scale research projects. © 2016 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.

International audience; Purpose The European Network of Biological and Physical Retrospective Dosimetry ‘RENEB’ has contributed to European radiation emergency preparedness. To give homogeneous dose estimation results, RENEB partners must harmonize their processes. Materials and methods A first inter-comparison focused on biological and physical dosimetry was used to detect the outliers in terms of dose estimation. Subsequently, trainings were organized to improve both tools dose estimation. A second inter-comparison was performed to validate training efficiency. Simultaneously, based on ISO standards, a QAandQM manual on all dosimetry assays was produced which states a common basis and harmonized procedures for each assay. The evaluation of the agreement of RENEB partners to follow the QAandQM manual was performed through a questionnaire. The integration of new members into the network was carried out in the same way, whatever the assays. Results The training courses on biological and physical dosimetry were judged to be successful because most of the RENEB members’ dose estimates improved in the second inter-comparison. The QAandQM manual describes the consensus for the minimum requirements and the performance criteria for both dosimetry assays. The questionnaire revealed that the whole network capacity currently can manage between 15 and 3800 samples once. Conclusion The methodology used to harmonize all dosimetry practice within the network RENEB was highly successful. The network is operational to manage a mass casualty radiation accident for immediate dose assessment. © 2016 The Author(s). Published by Informa UK Limited, trading as Taylor and Francis Group.

International audience; [No abstract available]

The properties of neutral acceptor states in zinc-blende semiconductors are re-examined in the frame of extended-basis $sp^3d^5s^*$ tight-binding model. The symmetry discrepancy between envelope function theory and atomistic calculations is explained in terms of over symmetric potential in current k$\cdot$p approaches. Spherical harmonics decomposition of microscopic Local Density Of States (LDOS) allows for the direct analysis of the tight-binding results in terms of envelope function. Lifting of degeneracy by strain and electric field and their effect on LDOS is examined. The fine structure of magnetic impurity caused by exchange interaction of hole with impurity $d$-shell and its dependence on strain is studied. It is shown that exchange interaction by mixing heavy and light hole makes the ground state more isotropic. The results are important in the context of Scanning Tunneling Microscopy (STM) images of subsurface impurities., 11 pages, 9 figures

For GaSb/AlSb heterostructures with the absolute conduction minimum deriving from the L point of the bulk Brillouin zone, we predict zero-field spin splittings well exceeding 10 meV, about one order of magnitude larger than typical values resulting from the Dresselhaus and Rashba spin-orbit coupling terms near the zone center. Electronic structure calculations are performed within an improved tight-binding model and the main results can be reproduced in a 4x4 k.p Hamiltonian including band parameters and k-linear spin splittings derived from the GaSb bulk. Our results provide direct insight into L-valley heterostructures, indicating a promising direction for future research on spintronics.

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Publisher: Springer Verlag; ISSN: 0933-033X; International audience

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We demonstrate strong confinement of the optical field by depositing a micron sized metallic disk on a planar interferential mirror. Zero dimensional Tamm plasmon modes are evidenced both experimentally and theoretically, with a lateral confinement limited to the disk area and strong coupling to TE polarized fields. Single quantum dots deterministically coupled to these modes are shown to experience acceleration of their spontaneous emission when spectrally resonant with the mode. For quantum dots spectrally detuned from the confined Tamm Plasmon mode, an inhibition of spontaneous emission by a factor 40 is observed, a record value in the optical domain.

In the first part of this review, we examined through an extensive literature review, the influence of various factors related to the individual (age, sex, alcohol and tobacco) on the rate of translocation. In the second part, our literature review focused on the study of more toxic factors related to occupational exposure. All toxic agents tested induced an increase in the translocation rate in lymphocytes of exposed people. However 2 agents (polycyclic aromatic hydrocarbons -PAHs- and heavy metals) increase significantly the rate of translocation of exposed persons. This increase is function to the dose and duration of exposure. The sensitivity of FISH technique has highlighted the necessity of protective equipment. For all the toxic factors related to occupational exposure, protective equipment or exposure conditions reduced significantly the translocations rate of exposed subjects. Thus the FISH technique could be an exposure warning indicator. In conclusion, it is important to know as well the personnel and occupational curriculum of an individual if a retrospective dose assessment is required. Thus, the rate of translocations threshold will be based on the lifestyle rate. © EDP Sciences, 2010.; Dans la première partie de cette revue, nous avons examiné, au travers d’une étude bibliographique approfondie, l’influence de différents facteurs liés à l’individu (âge, sexe, consommation d’alcool ou de tabac) sur le taux de translocations. Dans cette seconde partie, notre revue de la littérature s’est attachée à l’étude de facteurs plus toxiques liés à une exposition professionnelle. Tous les agents toxiques analysés induisent une augmentation du taux de translocations au sein des lymphocytes des personnes exposées. Cependant 2 agents (hydrocarbures aromatiques polycycliques –HAPs- et les métaux lourds) augmentent de manière significative le taux des translocations des personnes exposées. Ce type d’agents toxiques augmente le taux de translocations proportionnellement à la dose et à la durée d’exposition. La sensibilité de la technique FISH a permis de mettre en évidence la nécessité et le bon fonctionnement des équipements de protection. Pour tous les facteurs toxiques liés à une exposition professionnelle, un équipement de protection adapté et ergonomique ou bien la période d’exposition ont réduit significativement le taux de translocations des individus exposés. Ainsi la technique FISH pourrait servir d’indicateur d’exposition. En conclusion, afin d’évaluer rétrospectivement l’exposition d’un individu, il est important de connaitre le plus précisément possible son curriculum clastogène et son âge. Ainsi, un taux de translocations limite pourrait être établi en fonction de l’impact des expositions professionnelles et environnementales connues aujourd’hui et de la connaissance du passé de l’individu.

The assessment of exposure to ionizing radiation, carried out long time after exposure, is currently performed by scoring of translocations, a specific type of chromosomal aberrations. The translocations rate observed in peripheral blood lymphocytes of exposed subjects is compared to that observed in a control population. However, the translocation specificity towards radiation exposure is not clearly identified. To avoid any hasty conclusion, it is necessary to identify all the factors likely to induce translocation. To our knowledge, no study has thus far examined the effects of all these different factors on translocation rates. A review of the literature thus allowed us to assess the impact of host factors and lifestyle on the production of translocations. This study confirms that age appears to be the factor having the greatest impact on the rate of translocations, especially over 60 years. To date, the factor "age" is already considered in estimating the impact of radiation on the rate of translocation for all age groups. However, the study also shows that this rate varies significantly when the patient is exposed simultaneously and significantly towards many lifestyle agents. A precise threshold translocation rate should thus be established as a function of known behavioral exposures, below which it is impossible to conclude that radiological exposure has occurred. The effects of chemicals on the translocation rate after occupational exposure will be the subject of a second part. © EDP Sciences, 2010.; L’évaluation de l’exposition aux rayonnements ionisants, effectuée longtemps après l’exposition, est actuellement réalisée en dénombrant les aberrations chromosomiques de type translocations. Le taux de ces translocations observées dans les lymphocytes des personnes exposées est comparé au taux observé au sein d’une population contrôle. Toutefois, la spécificité des translocations vis-à-vis de l’irradiation n’est pas clairement identifiée. Afin d’éviter toute conclusion hâtive, il est nécessaire d’identifier tous les facteurs susceptibles d’induire des translocations. À notre connaissance, aucune synthèse sur l’effet de ces différents facteurs sur le taux de translocations n’a été réalisée à ce jour. Cette recherche bibliographique a confirmé l’impact de certains facteurs personnels sur l’augmentation des translocations. Cette étude corrobore que l’âge s’avère être le facteur ayant le plus d’impact sur le taux de translocations, notamment après 60 ans. À ce jour, le facteur « âge » est déjà considéré dans l’estimation du taux de translocations après suspicion d’exposition aux rayonnements ionisants pour toutes les classes d’âge. L’étude montre également que ce taux varie significativement lorsque le patient est exposé simultanément et de manière importante et chronique à une combinaison alcool et tabac. Ainsi, une courbe du taux de translocations devrait être établie en fonction de la consommation excessive de ce type d’agent pour chaque individu. Ainsi il serait alors possible de déterminer le taux de translocations induit uniquement par une exposition radiologique. Les effets des agents toxiques sur le taux de translocations après exposition professionnelle feront l’objet d’une deuxième partie.

Hanle effect is ubiquitous in the study of spin-related phenomena and has been used to determine spin lifetime, precession and transport in semiconductors. Here, we report an experimental observation of anomalous Hanle effect in individual self-assembled InAs/GaAs quantum dots where we find that a sizeable photo-created electron spin polarization can be maintained in transverse fields as high as 1T until it abruptly collapses. The striking broadening of the Hanle curve by a factor of ~20 and its bistability upon reversal of the magnetic sweep direction points to a novel dynamical nuclear spin polarization mechanism where the effective nuclear magnetic field compensates the transverse applied field. This interpretation is further supported by the measurement of actual electron Zeeman splitting which exhibits an abrupt increase at the Hanle curve collapse. Strong inhomogeneous quadrupolar interactions typical for strained quantum dots are likely to play a key role in polarizing nuclear spins perpendicular to the optically injected spin orientation., 5 pages,3 figures

International audience; Using "click chemistry" as an easy and versatile synthetic strategy to combine hyaluronan and polyglutamate blocks, we have prepared nanovesicles (polymersomes) that present a controlled size, excellent colloidal stability, and a high loading capacity for hydrophilic and hydrophobic drugs. The unique feature of our concept is the use of hyaluronan, a polysaccharide with known capacity for targeting cancer-related protein receptors, as the hydrophilic portion of a block copolymer system. The cytotoxicity and internalization mechanism of doxorubicin-loaded polymersomes have been evaluated in C6 glioma tumor cell lines. The dual purpose served by hyaluronan, as both a hydrophilic block critical to vesicle formation and as a binding agent for biological targets, breaks new ground in terms of multifunctional nanomaterial design for drug delivery.

24th European Photovoltaic Solar Energy Conference, 21-25 September 2009, Hamburg, Germany; 1118-1122, A new approach for realizing a defined texture on multicrystalline silicon for solar cells was investigated. The necessary etching mask is structured via UV-Nanoimprint Lithography as a potential substitute for photolithography. This emerging technology offers new possibilities in terms of resolution, shape of the structured patterns and requirements to the substrate´s surface quality. After the UV sensitive resist is structured and crosslinked, it serves as etching mask within a reactive ion etching process. To evaluate the quality of the textured surfaces, optical as well as electrical characterisation was conducted.

24th European Photovoltaic Solar Energy Conference, 21-25 September 2009, Hamburg, Germany; 1529-1533, The results in this publication show that it is possible to fabricate photonic crystals through spincoating of nano spheres made of Polymethylmethacrylate (PMMA) or SiO2, a subsequent infiltration with SiyC1-y using plasma enhanced chemical vapour deposition and optional burning out of the PMMA spheres. The structures are highly ordered and show enhanced reflectivity (600 nm spheres). An implementation of such structures into the process chain of high efficiency solar cells was done successfully. After passivating the solar cells rear side with SixC1-x and generating the photonic structure the rear metal contact was established with laser ablation and Al evaporation. Reflectivity measurements show reduced reflection for the

24th European Photovoltaic Solar Energy Conference, 21-25 September 2009, Hamburg, Germany; 1997-2000, In this paper, we report our investigation on the light trapping enhancement of silicon solar cells via the introduction of nanoscale gratings on the back side of solar cells. The grating is designed to diffract long wavelengths, typically from 900 nm to 1100 nm, leading to an enhancement of the photons path length in the solar cell. Therefore, a gain in current and then efficiency can be expected. The optimal grating parameters were first calculated via RCWA simulations, and were found to be a period of 310 nm for a flat front side and 410 nm for a textured front side. Test structures, with flat and textured front and back side and various silicon dioxide thicknesses on the back side, were then fabricated to confirm the simulation results. Reflection measurements performed on these test structures show a decrease of the reflection in that particular wavelength range for a flat front side. However, spectral response measurements of solar cells will be the only characterisation that can assure us that this decrease in reflection is inducing an increase of absorption in the silicon, as expected by simulation and not in the aluminium layer.

The 36th annual meeting of the European Radiation Research Society (ERRS), the ERR 2008 meeting, was organized by a team from the French Radiation protection and nuclear safety institute (IRSN) in Tours (France), from September 1st to 4th, 2008. More than 150 researchers and physicians, coming from all over the world participated in this meeting. Beyond these data, this meeting highlighted several major fields of research, among which biological dosimetry, genetic instability and bystander effects, and normal tissue damages. Epidemiological studies were also represented for the first time in an ERRS meeting. The goal of this paper is to present an overview of major results presented during this meeting. © 2009 EDP Sciences.; Le 36e congrès annuel de la société européenne de recherche sur les rayonnements (ERRS), l’ERR 2008, a été organisé par une équipe française de l’Institut de radioprotection et de sûreté nucléaire (IRSN), du 1er au 4 septembre 2008, à Tours (France). Ce congrès a rassemblé plus de 150 chercheurs et médecins venus du monde entier. Au-delà de ces chiffres, ce congrès a mis en avant plusieurs thèmes de recherche majeurs à l’heure actuelle et notamment la dosimétrie biologique, l’instabilité génétique et les effets de voisinage, et les dommages aux tissus sains. L’épidémiologie était également pour la première fois présente dans un congrès de l’ERRS. L’objectif de cet article est de faire un tour d’horizon rapide des résultats marquants présentés durant ce congrès.

We investigate exciton spin memory in individual InAs/GaAs self-assembled quantum dots via optical alignment and conversion of exciton polarization in a magnetic field. Quasiresonant phonon-assisted excitation is successfully employed to define the initial spin polarization of neutral excitons. The conservation of the linear polarization generated along the bright exciton eigenaxes of up to 90% and the conversion from circular- to linear polarization of up to 47% both demonstrate a very long spin relaxation time with respect to the radiative lifetime. Results are quantitatively compared with a model of pseudo-spin 1/2 including heavy-to-light hole mixing., 5 pages, 3 figures

23rd European Photovoltaic Solar Energy Conference and Exhibition, 1-5 September 2008, Valencia, Spain; 1149-1152, We report use of heavily doped polysilicon combined with a tunnel dielectric to provide an alternate to diffused junctions for silicon solar cells. Thin tunnel dielectrics (6-12Å) are fabricated using methods adapted from IC processing. These serve as diffusion barriers and passivation layers. When combined with heavily doped polysilicon, they can form an ideal step junction with interface passivation, enabling low dark currents not possible with diffused emitters. We show that it is possible to obtain hyper-abrupt junctions with the tunnel layer providing interface passivation, and that these junctions obtain a VOC of 676 mV on 780 μm thick substrates.

Effect of electric field on spin splitting in SiGe quantum wells (QWs) has been studied theoretically. Microscopical calculations of valley and spin splittings are performed in the effective $sp^3d^5s^*$ tight-binding model. The splittings oscillate as a function of the QW width due to inter-valley reflection of the electron wave off the interfaces. In accordance with the symmetry considerations additional electric-field-induced terms appear in the electron spin-dependent Hamiltonian. The oscillations of splitting are suppressed in rather low electric fields. The tight-binding calculations have been analyzed by using the envelope function approach extended to asymmetrical QWs., 8 pages, 3 figures

Mesenchymal stem cells (MSCs) have been shown to migrate to various tissues. There is little information on the fate and potential therapeutic efficacy of the reinfusion of MSCs following total body irradiation (TBI). We addressed this question using human MSC (hMSCs) infused to nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice submitted to TBI. Further, we tested the impact of additional local irradiation (ALI) superimposed to TBI, as a model of accidental irradiation. NOD/SCID mice were transplanted with hMSCs. Group 1 was not irradiated before receiving hMSC infusion. Group 2 received only TBI at a dose of 3.5 Gy, group 3 received local irradiation to the abdomen at a dose of 4.5 Gy in addition to TBI, and group 4 received local irradiation to the leg at 26.5 Gy in addition to TBI. Fifteen days after gamma irradiation, quantitative and spatial distribution of the hMSCs were studied. Histological analysis of mouse tissues confirmed the presence of radio-induced lesions in the irradiated fields. Following their infusion into nonirradiated animals, hMSCs homed at a very low level to various tissues (lung, bone marrow, and muscles) and no significant engraftment was found in other organs. TBI induced an increase of engraftment levels of hMSCs in the brain, heart, bone marrow, and muscles. Abdominal irradiation (AI) as compared with leg irradiation (LI) increased hMSC engraftment in the exposed area (the gut, liver, and spleen). Comparison of two local irradiations has shown that (LI) as compared with (AI) increased hMSC engraftment in the exposed area. An increase of hMSC engraftment in organs outside the fields of the ALI was also observed. Conversely, following LI, hMSC engraftment was increased in the brain as compared with AI. This study shows that engraftment of hMSCs in NOD/ SCID mice with significantly increased in response to tissue injuries following TBI with or without ALI. ALI induced an increase of the level of engraftment at sites outside the local irradiation field, thus suggesting a distant (abscopal) effect of radiation damage. This work supports the use of MSCs to repair damaged normal tissues following accidental irradiation and possibly in patients submitted to radiotherapy. © 2007 EDP Sciences.; Les cellules souches mésenchymateuses (CSM) sont présentes dans divers tissus de l’organisme adulte dont la moelle osseuse. In vitro, les CSM peuvent se différencier en de nombreux types cellulaires du mésoderme, de l’endoderme et de l’ectoderme ; in vivo, elles ont la capacité de migrer vers un organe lésé. Il existe cependant peu d’informations sur le devenir et le potentiel thérapeutique lors de l’injection de ces cellules souches dans un organisme ayant subit une irradiation accidentelle ou thérapeutique. Nos travaux ont permis de mettre en évidence la répartition spatiale et le taux de prise de greffe des CSM injectées par voie intraveineuse (IV) dans un organisme en fonction de la configuration pour une irradiation gamma. Les CSM ont été isolées à partir de moelle osseuse humaine (CSMh) et injectées à des souris immunodéficientes 24 heures après irradiation. Nous avons mis au point trois types de configurations, une configuration d’irradiation corps entier (ICE) à une dose sublétale de 3,5 Gy et deux configurations d’irradiations localisées, pour lesquelles les souris reçoivent une dose locale totale de 8 Gy au niveau de l’abdomen ou de 30 Gy au niveau de la patte droite postérieure. Le taux d’implantation des CSMh dans les différents organes de l’organisme 15 jours après irradiation a été quantifié par amplification du gène humain de la bêta-Globine par PCR. Puis leur localisation in situ a été mise en évidence par marquage immuno-histochimique de la bêta-2-microglobuline humaine sur des sections d’organes murins possédant de l’ADN humain. En absence d’irradiation, les CSMh ont été détectées en très faible quantité. En revanche, le taux de CSMh implantées est plus important au niveau des zones irradiées à forte dose, suggérant que la colonisation des CSMh dans les tissus après irradiation est dépendante de la configuration d’irradiation. L’implantation des CSMh dans les organes n’appartenant pas aux zones surexposées évoque un état inflammatoire généralisé radio-induit. Cette observation met en avant l’existence d’un effet à distance (abscopal) des atteintes tissulaires locales radio-induites. L’ensemble de nos résultats suggère que la thérapie cellulaire par les CSM pourrait être utilisée pour la régénération des tissus normaux lésés suite à une irradiation accidentelle ou chez les patients soumis à une radiothérapie.

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Poster P827

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It has been suggested that human Mesenchymal Stem Cells (hMSC) could be used to repair numerous injured tissues. We have studied the potential use of hMSC in order to limit radiation-induced skin lesions. Immunodeficient NOD/SCID mice were locally irradiated to the leg (30 Gy, dose rate 2.7 Gy/mn) using a 60Co source in order to induce a severe skin lesion. Cultured bone marrow hMSC were delivered intravenously to the mice. The irradiated skin samples were studied for the presence of the human cells, the severity of the lesions and the healing process. Macroscopic analysis and histology results showed that the lesions were evolving to a less severe degree of radiation dermatitis following hMSC transplant when compared to irradiated non-transplanted controls. Clinical scores for the studied skin parameters of treated mice were significantly improved. A faster healing was observed when compared to untreated mouse. Immunohistology and Polymerase Chain reaction (PCR) analysis provided evidence that the human cells were found in the irradiated area. These results suggest a possible use of hMSC for the treatment of the early phase of the cutaneous radiation syndrome. A successful transplant of stem cells and subsequent reduction in radiation-induced complication may open the road to completely new strategies in cutaneous radiation syndrome therapy. © 2006 EDP Sciences.; De nombreuses études suggèrent que les cellules souches adultes et plus particulièrement les cellules souches Mésenchymateuses humaines (CSMh) pourraient être utilisées pour réparer de nombreux organes. Nous avons étudié la capacité des CSMh à réduire les lésions cutanées radio induite. Pour induire des lésions sévères de la peau, des souris NOD/SCID ont été irradiées au niveau de la patte droite postérieure (30 Gy, débit 2,7 Gy/mn) en utilisant une source gamma au 60Co. Les CSMh ont été injectées 24 heures après irradiation par voie intraveineuse. La présence de cellules humaines, la sévérité des lésions et les processus de cicatrisation ont été étudiés sur les échantillons de peau prélevés de 3 à 8 semaines après irradiation. Nous avons pu observer que chez les souris greffées avec des CSMh, le niveau d’atteinte cutanée radio induite est significativement plus faible. Les scores cliniques utilisés pour l’étude de l’évolution des lésions cutanées de la peau sont significativement améliorés et une cicatrisation plus rapide est observée en comparaison des souris non injectées. La présence de cellules humaines a pu être détectée par PCR quantitative dans les zones cutanées en cours de cicatrisation. Ces résultats suggèrent premièrement que les CSMh sont capables de coloniser la peau altérée par les rayonnements ionisants et deuxièmement qu’elles accélèrent le processus de réparation de ce tissu limitant ainsi les complications tissulaires radio induites. La greffe de CSMh pourrait être un traitement thérapeutique efficace des phases précoces du syndrome cutané radio induit.

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Cytochromes P450 (CYPs) are a superfamily of 57 genes coding for drug metabolizing enzymes and endobiotic metabolizing enzymes (steroids, eicosanoids, vitamins...). This is the main metabolizing enzyme system for foreign compounds, including drugs, which has a primary role in organism protection against potential harmful insults from the environment (pollutants, pesticides...). The CYPs regulation is essentially transcriptional: nuclear receptors are recognized as key mediators for the control of drug metabolizing enzymes. Their ligands are exogenous and also endogenous molecules that can up-regulate or down-regulate these transcription factors. Treatment with drugs or xenobiotics, which are nuclear receptor agonists or antagonists, can lead to severe toxicities, loss of therapeutic effect or endobiotic metabolism disorders. Genetic polymorphisms of these enzymes have an important role in their activity and must be taken into account during drug administration. Then, CYP activity depends on genotype and environment; this is recently used as biomarker to determine human exposure to environmental molecules or to predict the susceptibility to certain pathologies.

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We show that optical pumping of electron spins in individual InGaAs quantum dots leads to strong nuclear polarisation that we measure via the Overhauser shift (OHS) in magneto-photoluminescence experiments between 0 and 4T. We find a strongly non-monotonous dependence of the OHS on the applied magnetic field, with a maximum nuclear polarisation of 40% for intermediate magnetic fields. We observe that the OHS is larger for nuclear fields anti-parallel to the external field than in the parallel configuration. A bistability in the dependence of the OHS on the spin polarization of the optically injected electrons is found. All our findings are qualitatively understood with a model based on a simple perturbative approach., Comment: Phys Rev B (in press)

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Polarization resolved photoluminescence (PL) spectroscopy of individual CdTe/ZnTe quantum dots is investigated in the presence of external in-plane magnetic field. We find that the excitonic fine structure strongly depends on the magnitude and direction of applied field. The splitting between "bright" and "dark" states increases with the magnetic field, whereas the anisotropic exchange splitting of the bright excitons can be reduced or enhanced, depending on the field direction. Increase (decrease) is observed when the field is applied parallel to the PL polarization direction of the lower (upper) energy exciton. For intermediate fields, we observe a rotation of the PL polarization orientation. The results are discussed in terms of an effective spin Hamiltonian derived for the exciton ground state., Comment: 6 pages, 6 figures

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Biological dosimetry, which determines the absorbed dose of radiation by measuring radiation-induced variation of various biological parameters, can help to assess radiation damage in a given patient and evaluate his or her sensitivity to radiation. The chromosomal aberration count in circulating lymphocytes is considered to be the most specific as well as the most sensitive method for measuring radiation exposure; as such, it is used in forensic medicine. Evaluation of radiation exposure requires setting up reference curves for each type of radiation. In nuclear medicine, exposure is currently calculated mathematically and not by considering its biological consequences. Biological dosimetry uses a more realistic approach towards the consequences of radiations received during an examination in nuclear medicine. The aim of the study was to evaluate the long-term consequences of the in vivo administration of 99mTc-sodium oxidronate (HDP), on the basis of the induction of stable chromosomal aberrations. Stable aberrations were scored before and after administration of the 99mTc-labelled radiopharmaceutical. First, a specific relationship between the dose of 99mTc and the frequency ofstable chromosomal aberrations was established in vitro to estimate whole-body dose. Six volunteer patients were included in the study. Blood samples were obtained before and 6 and/or 24 hours after 99mTc-HDP administration. Stable chromosomal aberrations in irradiated lymphocytes were scored using fluorescence in situ hybridization using human whole-chromosome-specific DNA probes for chromosomes 2, 4 and 12. Analysis of the in vitro data shows that the number of translocations has a quadratic linear relationship with the administered dose. Systemic administration of 99mTc-HDP at routine activity did not induce additional early translocations over the background level. Translocation scoring performed months or even years after the administration of 99mTc-HDP could be necessary to rule out side effects on bone marrow stem cells.

In biological dosimetry the reference technique is based on the scoring of dicentics and centric rings induced by ionizing radiation. This article tends to present some image analysis systems used in biological dosimetry to help aberration detection. The presented systems are: the CYTOGEN from IMSTAR society, the CYTOSCAN (APPLIED IMAGING) and the METAFER (METASYSTEM). All 3 systems do not present similar functionalities but offer different way of automation. Some functionalities of these systems are compared. The systems can assist operators on 3 major points: (1) an automatic metaphase finder, in this case, the time benefic ranges from 2 to 4 when compared to manual scoring; (2) a specific tool to help manual scoring of aberrations, this provide an easier scoring and a better stability of the results; (3) the automatic detection of dicentrics, very useful in case of population triage. In this case, the dose has to be established very quickly, on a large population. However, the precision on the dose can be reduced compared to individual dose estimation. Some uncertainties on the detection of dicentric are acceptable and dicentric detection can be automated. Time benefic is then very important as 300 cells can be analyzed in half an hour (METAFER) against 25 when the metaphase finder is used alone. However, only 50% of the dicentrics are detected therefore it would be interesting to increase the efficiency of the detection. The use of the FISH technique could allow a better detection of dicentrics, the first results are promising (90% of centromeres correctly detected) but more experiments are required to evaluate the time benefit. © EDP Sciences, 2003.; La technique de référence en dosimétrie biologique est basée sur le dénombrement des aberrations chromosomiques de type dicentrique induit par les rayonnements ionisants. Cet article présente divers systèmes d'analyse d'images utilisés en dosimétrie biologique pour aider la détection de ces aberrations. Les systèmes présentés sont le CYTOGEN de la société IMSTAR, le CYTOSCAN (APPLIED IMAGING) et le METAFER (METASYSTEM). Tous ne présentent pas les mêmes fonctionnalités et chacun peut être utilisé de façon plus ou moins automatique. Certaines fonctionnalités communes de ces systèmes sont comparées. L'aide apportée par les systèmes porte sur 3 points : (1) localisation automatique des métaphases sur les lames, dans ce cas on a un gain de temps d'un facteur 2 à 4 par rapport au comptage manuel ; (2) un outil d'aide au comptage qui apporte un confort de lecture et une meilleure fiabilité des résultats ; (3) la détection automatique des dicentriques est particulièrement utile en cas de tri de population. En effet, dans ce cas il faut estimer très rapidement la dose reçue par un nombre important de personnes. Par contre, l'estimation de dose n'a pas besoin d'être aussi précise que dans le cas de l'expertise individuelle. Des erreurs dans la détection des dicentriques est alors tolérée et une détection automatique des dicentriques est envisageable. Le gain de temps est très appréciable puisqu'il est possible de compter 300 cellules en une demie-heure (METAFER) contre 25 avec la seule aide du chercheur de métaphases. Cependant la qualité de la détection doit encore être améliorée puisque 50 % des dicentriques ne sont pas détectées. Le marquage des centromères par technique FISH devrait permettre d'améliorer la sensibilité de la technique. Les premiers résultats sont encourageant puisque 90 % des centromères sont correctements détectés mais d'autres expériences doivent être réalisées pour évaluer le gain de temps.

Biological dosimetry, which determines the absorbed dose of radiation by measuring radiation-induced variation of various biological parameters, can help to assess radiation damage in a given patient and evaluate his or her sensitivity to radiation. The chromosomal aberration count in circulating lymphocytes is considered to be the most specific as well as the most sensitive method for measuring radiation exposure; as such, it is used in forensic medicine. Evaluation of radiation exposure requires setting up reference curves for each type of radiation. In nuclear medicine, exposure is currently calculated mathematically and not by considering its biological consequences. Biological dosimetry uses a more realistic approach towards the consequences of radiations received during an examination in nuclear medicine. The aim of the study was to evaluate the long-term consequences of the in vivo administration of 99mTc-sodium oxidronate (HDP), on the basis of the induction of stable chromosomal aberrations. Stable aberrations were scored before and after administration of the 99mTc-labelled radiopharmaceutical. First, a specific relationship between the dose of 99mTc and the frequency ofstable chromosomal aberrations was established in vitro to estimate whole-body dose. Six volunteer patients were included in the study. Blood samples were obtained before and 6 and/or 24 hours after 99mTc-HDP administration. Stable chromosomal aberrations in irradiated lymphocytes were scored using fluorescence in situ hybridization using human whole-chromosome-specific DNA probes for chromosomes 2, 4 and 12. Analysis of the in vitro data shows that the number of translocations has a quadratic linear relationship with the administered dose. Systemic administration of 99mTc-HDP at routine activity did not induce additional early translocations over the background level. Translocation scoring performed months or even years after the administration of 99mTc-HDP could be necessary to rule out side effects on bone marrow stem cells.

Purpose: Phosphodiesterase 6 (PDE6) is the primary effector of phototransduction in vertebrate photoreceptors. Previous studies described the expression of the regulatory subunit of rod PDE6 (Pγ-rod) in non-photosensitive tissues of the adult rat and the effects of this protein on MAP kinase pathways. Upon examination of the Pγ-rod sequence, we detected a proline-rich domain that might reveal its ability to interact with SH3-containing proteins. Therefore, the present study was initiated to identify new protein partners of Pγ-rod. Methods: A yeast two-hybrid screen of a rat brain cDNA library was performed using Pγ-rod as a bait. Pγ-rod-SH3 interaction was confirmed by GST pull-down of in vitro-translated proteins. The aminoacids involved in the interaction were mapped by site-directed mutagenesis. Rnase protection assay, RT-PCR and western blot analysis were used to detect Pγ-rod expression in various rat tissues. Results: A clone was isolated twice, that consisted essentially of the SH3 domain of the formin-binding protein 17 (FBP17). This interaction was confirmed by GST pull-down. Mutational analysis of the Pγ-rod-FBP17 interaction confirmed it involved the proline-rich domain of Pγ-rod and the SH3 domain of FBP17. This proline-rich domain also allowed Pγ-rod to interact with Cdc42-interacting protein 4 (CIP4), another SH3-containing protein. RT-PCR and Rnase protection assay detected different amounts of Pγ-rod mRNA in adult and embryonic rat tissues. Western blots confirmed the presence of low levels of Pγ-rod protein only in embryonic tissues. Conclusions: Our data suggest that Pγ-rod participates in SH3-mediated cellular pathways and may therefore play a wider role than previously appreciated. One possibility is that FBP17 interaction with sorting nexin 2 might connect Pγ- rod to receptor tyrosine kinase recycling. However, further studies are still required to identify the diversity of SH3- containing proteins that interact with Pγ-rod. This effort should provide a rationale to understand how Pγ-rod can affect receptor internalization-dependent MAP kinase activity.