First direct observation of two protons in the decay of 45^{45}Fe with a TPC

The decay of the ground-state two-proton emitter 45Fe was studied with a time-projection chamber and the emission of two protons was unambiguously identified. The total decay energy and the half-life measured in this work agree with the results from previous experiments. The present result constitutes the first direct observation of the individual protons in the two-proton decay of a long-lived ground-state emitter. In parallel, we identified for the first time directly two-proton emission from 43Cr, a known beta-delayed two-proton emitter. The technique developped in the present work opens the way to a detailed study of the mechanism of ground-state as well as beta-delayed two-proton radioactivity.Comment: 4 pages, 5 figure

MAYA: An active-target detector for binary reactions with exotic beams

International audienceWith recent improvements in the production of radioactive beams in facilities such as SPIRAL at GANIL, a larger area of the nuclear chart is now accessible for experimentation. For these usually low-intensity and low-energy secondary beams, we have developed the new MAYA detector based on the active-target concept. This device allows to use a relatively thick target without loss of resolution by using the detection gas as target material. Dedicated 3D tracking, particle identification, energy loss and range measurements allow complete kinematic reconstruction of reactions taking place inside MAYA

Tracking algorithms for the active target MAYA

The MAYA detector is a Time-Charge Projection Chamber based on the concept of active target. These type of devices use a part of the detection system, the filling gas in this case, in the role of reaction target. The MAYA detector performs three-dimensional tracking, in order to determine physical observables of the reactions occurring inside the detector. The reconstruction algorithms of the tracking use the information from a two-dimensional projection on the segmented cathode, and, in general, they need to be adapted for the different experimental settings of the detector. This work presents some of the most relevant solutions developed for the MAYA detector

The N=14 shell closure in 22^{22}O viewed through a neutron sensitive probe

NESTER PTHInternational audienceTo investigate the behavior of the N=14 neutron gap far from stability with a neutron-sensitive probe, proton elastic and 2+1 inelastic scattering angular distributions for the neutron-rich nucleus 22O were measured with a secondary beam intensity of only 1200 particles per second using the MUST silicon strip detector array at the GANIL facility. A phenomenological analysis yields a deformation parameter bp;p' = 0.26 +- 0.04 for the 2+1 state, much lower than in 20O, showing a surprisingly weak neutron contribution to this state. A fully microscopic analysis was performed using optical potentials obtained from matter and transition densities generated by continuum Skyrme-HFB and QRPA calculations, respectively. When the present results and those from a 22O + 197Au scattering experiment are combined, the ratio of neutron to proton contributions to the 2+1 state is found close to the N/Z ratio, demonstrating a strong N=14 shell closure in the vicinity of the neutron drip-line

Ion slowing down and charge exchange at small impact parameters selected by channeling: superdensity effects

CASInternational audienceIn two experiments performed with 20-30 MeV/u highly charged heavy ions (Pb56+, U91+) channeled through thin silicon crystals, we observed the original features of superdensity, associated to the glancing collisions with atomic rows undergone by part of the incident projectiles. In particular the very high collision rate yields a quite specific charge exchange regime, that leads to a higher ionization probability than in random conditions. X-ray measurements show that electrons captured in outershells are prevented from being stabilized, which enhances the lifetime of the projectile innershell vacancies. The charge state distributions and the energy loss spectra are compared to Monte-Carlo simulations. These simulations confirm, extend and illustrate the qualitative analysis of the experimental results

Inverse kinematics proton scattering from the exotic nucleus 22^{22}O

NESTER PTHInternational audienceWe have measured for the first time elastic and inelastic proton scattering from the neutron rich nucleus 22O at 46.6 AMeV using the MUST array

Kinesin 9 family members perform separate functions in the trypanosome flagellum

KIF9B localizes to the axoneme and basal body and is needed for flagella assembly, whereas KIF9A localizes only to the axoneme and controls flagella motility without affecting their structure

Deregulation and Targeting of TP53 Pathway in Multiple Myeloma

Multiple Myeloma (MM) is an incurable disease characterized by a clonal evolution across the course of the diseases and multiple lines of treatment. Among genomic drivers of the disease, alterations of the tumor suppressor TP53 are associated with poor outcomes. In physiological situation, once activated by oncogenic stress or DNA damage, p53 induces either cell-cycle arrest or apoptosis depending on the cellular context. Its inactivation participates to drug resistance in MM. The frequency of TP53 alterations increases along with the progression of the disease, from 5 at diagnosis to 75% at late relapses. Multiple mechanisms of regulation lead to decreased expression of p53, such as deletion 17p, TP53 mutations, specific microRNAs overexpression, TP53 promoter methylations, and MDM2 overexpression. Several therapeutic approaches aim to target the p53 pathway, either by blocking its interaction with MDM2 or by restoring the function of the altered protein. In this review, we describe the mechanism of deregulation of TP53 in MM, its role in MM progression, and the therapeutic options to interact with the TP53 pathway

Flagellar incorporation of proteins follows at least two different routes in trypanosomes

International audienceBackground information: Eukaryotic cilia and flagella are sophisticated organelles composed of several hundreds of proteins that need to be incorporated at the right time and the right place during assembly.Results: Two methods were used to investigate this process in the model protist Trypanosoma brucei: inducible expression of epitope-tagged labelled proteins and fluorescence recovery after photobleaching of fluorescent fusion proteins. This revealed that skeletal components of the radial spokes (RSP3), the central pair (PF16) and the outer dynein arms (DNAI1) are incorporated at the distal end of the growing flagellum. They display low or even no visible turnover in mature flagella, a finding further confirmed by monitoring a heavy chain of the outer dynein arm. In contrast, the membrane-associated protein arginine kinase 3 (AK3) showed rapid turnover in both growing and mature flagella, without particular polarity and independently of intraflagellar transport.Conclusion: These results demonstrate different modes of incorporation for structural and membrane-associated proteins in flagella.Significance: The existence of two distinct modes for incorporation of proteins in growing flagella suggests the existence of different targeting machineries. Moreover, the absence of turnover of structural elements supports the view that the length of the mature flagellum in trypanosomes is not modified after assembly