Properties of the CsI(Tl) detector elements of the CALIFA detector

In the R3B experiment at FAIR, charged particles with energies up to 600 MeV and forward boosted γ-rays with energies up to 20 MeV need to be detected in scattering experiments. Calorimeters for nuclear physics experiments of this kind, using relativistic radioactive ion beams, require high energy resolution and high efficiency for simultaneous detection of strongly Doppler shifted γ-rays and high-energy charged particles. A calorimeter design that can meet these requirements, using CsI(Tl) scintillators, results in detector elements that may exhibit light output variations with crystal depth, which can limit the attainable resolution. In this paper we present results from a systematic study of 478 detector modules of CALIFA, the R3B calorimeter, in order to determine and minimize such variations. To facilitate further systematic studies we also present results for the total absorption length of the scintillation light, using spectrophotometry, light crosstalk between adjacent detector modules, and surface topography of the CsI(Tl) crystals from atomic force microscopy.Swedish research council | Ref. 2017-03986Swedish research council | Ref. 2014-06644Swedish research council | Ref. 2013-04178Swedish research council | Ref. 2012-04550BMBF, Alemania | Ref. 05P15WOFNABMBF, Alemania | Ref. 05P19WOFN1BMBF, Alemania | Ref. 05P15RDFN1BMBF, Alemania | Ref. 05P19RDFN

Dbx1-Expressing Cells Are Necessary for the Survival of the Mammalian Anterior Neural and Craniofacial Structures

Development of the vertebrate forebrain and craniofacial structures are intimately linked processes, the coordinated growth of these tissues being required to ensure normal head formation. In this study, we identify five small subsets of progenitors expressing the transcription factor dbx1 in the cephalic region of developing mouse embryos at E8.5. Using genetic tracing we show that dbx1-expressing cells and their progeny have a modest contribution to the forebrain and face tissues. However, their genetic ablation triggers extensive and non cell-autonomous apoptosis as well as a decrease in proliferation in surrounding tissues, resulting in the progressive loss of most of the forebrain and frontonasal structures. Targeted ablation of the different subsets reveals that the very first dbx1-expressing progenitors are critically required for the survival of anterior neural tissues, the production and/or migration of cephalic neural crest cells and, ultimately, forebrain formation. In addition, we find that the other subsets, generated at slightly later stages, each play a specific function during head development and that their coordinated activity is required for accurate craniofacial morphogenesis. Our results demonstrate that dbx1-expressing cells have a unique function during head development, notably by controlling cell survival in a non cell-autonomous manner

Phosphorylation of a splice variant of collapsin response mediator protein 2 in the nucleus of tumour cells links cyclin dependent kinase-5 to oncogenesis

Background Cyclin-dependent protein kinase-5 (CDK5) is an unusual member of the CDK family as it is not cell cycle regulated. However many of its substrates have roles in cell growth and oncogenesis, raising the possibility that CDK5 modulation could have therapeutic benefit. In order to establish whether changes in CDK5 activity are associated with oncogenesis one could quantify phosphorylation of CDK5 targets in disease tissue in comparison to appropriate controls. However the identity of physiological and pathophysiological CDK5 substrates remains the subject of debate, making the choice of CDK5 activity biomarkers difficult. Methods Here we use in vitro and in cell phosphorylation assays to identify novel features of CDK5 target sequence determinants that confer enhanced CDK5 selectivity, providing means to select substrate biomarkers of CDK5 activity with more confidence. We then characterize tools for the best CDK5 substrate we identified to monitor its phosphorylation in human tissue and use these to interrogate human tumour arrays. Results The close proximity of Arg/Lys amino acids and a proline two residues N-terminal to the phosphorylated residue both improve recognition of the substrate by CDK5. In contrast the presence of a proline two residues C-terminal to the target residue dramatically reduces phosphorylation rate. Serine-522 of Collapsin Response Mediator-2 (CRMP2) is a validated CDK5 substrate with many of these structural criteria. We generate and characterise phosphospecific antibodies to Ser522 and show that phosphorylation appears in human tumours (lung, breast, and lymphoma) in stark contrast to surrounding non-neoplastic tissue. In lung cancer the anti-phospho-Ser522 signal is positive in squamous cell carcinoma more frequently than adenocarcinoma. Finally we demonstrate that it is a specific and unusual splice variant of CRMP2 (CRMP2A) that is phosphorylated in tumour cells. Conclusions For the first time this data associates altered CDK5 substrate phosphorylation with oncogenesis in some but not all tumour types, implicating altered CDK5 activity in aspects of pathogenesis. These data identify a novel oncogenic mechanism where CDK5 activation induces CRMP2A phosphorylation in the nuclei of tumour cells

A Novel Role for Dbx1-Derived Cajal-Retzius Cells in Early Regionalization of the Cerebral Cortical Neuroepithelium

Patterning of the cerebral cortex during embryogenesis depends not only on passive diffusion of morphogens but also on signal delivery by Cajal-Retzius neurons that migrate over long distances

Appreciation de l'effet a long terme de la nature organique ou minerale de la fertilisation sur la composition de la laitue et de la pomme de terre

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Processus de vieillissement chez des patients âgés dialysés

International audienceEn référence à la psychopathologie, les auteurs mettent en évidence plusieurs indicateurs du fonctionnement psychique du patient âgé dialysé. L'objectif princeps de ce travail est de dégager des indicateurs du fonctionnement psychique des patients âgés dialysés afin de les aider à " réussir " leur vieillissement, malgré la maladie, la lourdeur des soins et leurs effets secondaires