Noise at a Fermi-edge singularity

We present noise measurements of self-assembled InAs quantum dots at high magnetic fields. In comparison to I-V characteristics at zero magnetic field we notice a strong current overshoot which is due to a Fermi-edge singularity. We observe an enhanced suppression in the shot noise power simultaneous to the current overshoot which is attributed to the electron-electron interaction in the Fermi-edge singularity

Enhanced Shot Noise in Tunneling through a Stack of Coupled Quantum Dots

We have investigated the noise properties of the tunneling current through vertically coupled self-assembled InAs quantum dots. We observe super-Poissonian shot noise at low temperatures. For increased temperature this effect is suppressed. The super-Poissonian noise is explained by capacitive coupling between different stacks of quantum dots

Measurement of the electron drift velocity for directional dark matter detectors

Three-dimensional track reconstruction is a key issue for directional Dark Matter detection. It requires a precise knowledge of the electron drift velocity. Magboltz simulations are known to give a good evaluation of this parameter. However, large TPC operated underground on long time scale may be characterized by an effective electron drift velocity that may differ from the value evaluated by simulation. In situ measurement of this key parameter is hence a way to avoid bias in the 3D track reconstruction. We present a dedicated method for the measurement of the electron drift velocity with the MIMAC detector. It is tested on two gas mixtures : $\rm CF_4$ and $\rm CF_4+CHF_3$. We also show that adding $\rm CHF_3$ allows us to lower the electron drift velocity while keeping almost the same Fluorine content of the gas mixture.Comment: Proceedings of the 4th international conference on Directional Detection of Dark Matter (CYGNUS 2013), 10-12 June 2013, Toyama, Japa

In situ measurement of the electron drift velocity for upcoming directional Dark Matter detectors

Three-dimensional track reconstruction is a key issue for directional Dark Matter detection and it requires a precise knowledge of the electron drift velocity. Magboltz simulations are known to give a good evaluation of this parameter. However, large TPC operated underground on long time scale may be characterized by an effective electron drift velocity that may differ from the value evaluated by simulation. In situ measurement of this key parameter is hence needed as it is a way to avoid bias in the 3D track reconstruction. We present a dedicated method for the measurement of the electron drift velocity with the MIMAC detector. It is tested on two gas mixtures: CF4 and CF4 + CHF3. The latter has been chosen for the MIMAC detector as we expect that adding CHF3 to pure CF4 will lower the electron drift velocity. This is a key point for directional Dark Matter as the track sampling along the drift field will be improved while keeping almost the same Fluorine content of the gas mixture. We show that the drift velocity at 50 mbar is reduced by a factor of about 5 when adding 30% of CHF3.Comment: 19 pages, 14 figures. Minor corrections, matches published version in JINS

Long thoracic nerve release for scapular winging: Clinical study of a continuous series of eight patients

SummaryScapular winging secondary to serratus anterior muscle palsy is a rare pathology. It is usually due to a lesion in the thoracic part of the long thoracic nerve following violent upper-limb stretching with compression on the nerve by the anterior branch of thoracodorsal artery at the “crow's foot landmark” where the artery crosses in front of the nerve. Scapular winging causes upper-limb pain, fatigability or impotence. Diagnosis is clinical and management initially conservative. When functional treatment by physiotherapy fails to bring recovery within 6months and electromyography (EMG) shows increased distal latencies, neurolysis may be suggested. Muscle transfer and scapula-thoracic arthrodesis are considered as palliative treatments. We report a single-surgeon experience of nine open neurolyses of the thoracic part of the long thoracic nerve in eight patients. At 6months’ follow-up, no patients showed continuing signs of winged scapula. Control EMG showed significant reduction in distal latency; Constant scores showed improvement, and VAS-assessed pain was considerably reduced. Neurolysis would thus seem to be the first-line surgical attitude of choice in case of compression confirmed on EMG. The present results would need to be confirmed in larger studies with longer follow-up, but this is made difficult by the rarity of this pathology.Level of evidenceIII

MIMAC: MIcro-tpc MAtrix of Chambers for dark matter directional detection

Directional detection of non-baryonic Dark Matter is a promising search strategy for discriminating WIMP events from neutrons, the ultimate background for dark matter direct detection. This strategy requires both a precise measurement of the energy down to a few keV and 3D reconstruction of tracks down to a few mm. The MIMAC (MIcro-tpc MAtrix of Chambers) collaboration has developed in the last years an original prototype detector based on the direct coupling of large pixelized micromegas with a special developed fast self-triggered electronics showing the feasibility of a new generation of directional detectors. The first bi-chamber prototype has been installed at Modane, underground laboratory in June 2012. The first undergournd background events, the gain stability and calibration are shown. The first spectrum of nuclear recoils showing 3D tracks coming from the radon progeny is presented.Comment: Proceedings of the 4th International Conference on Directional Dark Matter Detection CYGNUS2013, held in Toyoma (Japan), June 201

Determination of the Properties of Composite Materials Thanks to Digital Image Correlation Measurements

AbstractDesigning composite structures for civil aircrafts necessitates a better understanding of the damage and failure mechanisms occurring in these components through experimental test campaigns and associated numerical simulations. These experimental tests have been performed at Onera using different classical measurement techniques (LVDT sensor, strain gauges…) and digital image correlation (DIC). The additional information provided by DIC allows (i) to validate the boundary conditions of the tests, (ii) to cross-check the measurements with other techniques, (iii) to improve the understanding of the physical mechanisms and (iv) to validate the predictions of the finite element simulations

Wavefront outer scale deduced from interferometric dispersed fringes

Astronomy and Astrophysics, v. 448, p. 1225-1234, 2006. http://dx.doi.org/10.1051/0004-6361:20052806International audienc