Impact of strain on the optical fingerprint of monolayer transition metal dichalcogenides

Strain presents a straightforward tool to tune electronic properties of atomically thin nanomaterials that are highly sensitive to lattice deformations. While the influence of strain on the electronic band structure has been intensively studied, there are only few works on its impact on optical properties of monolayer transition metal dichalcogenides (TMDs). Combining microscopic theory based on Wannier and Bloch equations with nearestneighbor tight-binding approximation, we present an analytical view on how uni- and biaxial strain influences the optical fingerprint of TMDs including their excitonic binding energy, oscillator strength, optical selection rules, and the radiative broadening of excitonic resonances. We show that the impact of strain can be reduced to changes in the lattice structure (geometric effect) and in the orbital functions (overlap effect). In particular, we demonstrate that the valley-selective optical selection rule is softened in the case of uniaxial strain due to the introduced asymmetry in the lattice structure. Furthermore, we reveal a considerable increase of the radiative dephasing due to strain-induced changes in the optical matrix element and the excitonic wave functions

Analyzing laser-plasma interferograms with a Continuous Wavelet Transform Ridge Extraction technique: the method

Laser-plasma interferograms are currently analyzed by extracting the phase-shift map with FFT techniques (K.A.Nugent, Applied Optics {\bf 18}, 3101 (1985)). This methodology works well when interferograms are only marginally affected by noise and reduction of fringe visibility, but it can fail in producing accurate phase-shifts maps when dealing with low-quality images. In this paper we will present a novel procedure for the phase-shift map computation which makes an extensive use of the Ridge Extraction in the Continuous Wavelet Transform (CWT) framework. The CWT tool is {\it flexible} because of the wide adaptability of the analyzing basis and it can be very {\it accurate} because of the intrinsic noise reduction in the Ridge Extraction. A comparative analysis of the accuracy performances of the new tool and the FFT-based one shows that the CWT-based tool phase maps are considerably less noisy and it can better resolve local inhomogeneties

Towards generic satellite payloads: software radio

Satellite payloads are becoming much more complex with the evolution towards multimedia applications. Moreover satellite lifetime increases while standard and services evolve faster, necessitating a hardware platform that can evolves for not developing new systems on each change. The same problem occurs in terrestrial systems like mobile networks and a foreseen solution is the software defined radio technology. In this paper we describe a way of introducing this concept at satellite level to offer to operators the required flexibility in the system. The digital functions enabling this technology, the hardware components implementing the functions and the reconfiguration processes are detailed. We show that elements of the software radio for satellites exist and that this concept is feasible

Critical-like gelation dynamics in cellulose nanocrystal suspensions

We use time-resolved mechanical spectroscopy to offer a detailed picture of the gelation dynamics of cellulose nanocrystal (CNC) suspensions following shear cessation in the presence of salt. CNCs are charged, rodlike colloids that self-assemble into various phases, including physical gels serving as soft precursors for biosourced composites. Here, series of linear viscoelastic spectra acquired across the sol-gel transition of CNC suspensions are rescaled onto two master curves, that correspond to a viscoelastic liquid state prior to gelation and to a soft solid state after gelation. These two states are separated by a critical gel point, where all rescaling parameters diverge in an asymmetric fashion, yet with exponents that obey hyperscaling relations consistent with previous works on isotropic colloids and polymer gels. Upon varying the salt content, we further show that these critical-like dynamics result in both time-connectivity and time-concentration superposition principles.Comment: 8 pages, 3 figures, supplementary information (2 pages, 2 figures, one table

La Bible grecque des Septante : histoire du texte et de sa réception juive et chrétienne – lecture et commentaire du deuxième livre des Règnes

Cette année, le cycle de conférences a présenté deux volets : 1) d’abord, une série de six conférences sur la question de la pluralité textuelle des Écritures dans l’Antiquité juive et chrétienne ; 2) ensuite, la reprise de la lecture, de la traduction et du commentaire du deuxième livre des Règnes dans la Septante

Word and bit line operation of a 1x1 {\mu}m2 superconducting vortex-based memory

The lack of dense random access memory is one of the main bottlenecks for the creation of a digital superconducting computer. In this work we study experimentally vortex-based superconducting memory cells. Three main results are obtained. First, we test scalability and demonstrate that the cells can be straightforwardly miniaturized to submicron sizes. Second, we emphasize the importance of conscious geometrical engineering. In the studied devices we introduce an asymmetric easy track for vortex motion and show that it enables a controllable manipulation of vortex states. Finally, we perform a detailed analysis of word and bit line operation of a 1x1 {\mu}m2 cell. High-endurance, nonvolatile operation at zero magnetic field is reported. Remarkably, we observe that the combined word and bit line threshold current is significantly reduced compared to the bare word-line operation. This could greatly improve the selectivity of individual cell addressing in a multibit RAM. The achieved one square micron area is an important milestone and a significant step forward towards creation of a dense cryogenic memory.Comment: 9 pages, 6 figure

La Bible grecque des Septante : lecture et commentaire du deuxième livre des Règnes

I. Objectifs du travail Le cycle de conférences fut consacré à lire, traduire et commenter le deuxième livre des Règnes dans la Bible grecque (2 Samuel, dans la Bible hébraïque), jusqu’au chapitre 19, dans l’optique de la parution prochaine, aux éditions du Cerf, d’un volume de la Bible d’Alexandrie. Le travail, commencé quelques années auparavant, m’avait amené à confier à Camille Lepeigneux un sujet de M2 consacré à la danse de David, et à Malouine de Dieuleveult un autre sujet de M2 sur le..

A validation study comparing self-reported travel diaries and objective data obtained from in-vehicle monitoring devices in older drivers with bilateral cataract

Background: Advances in technology have made it possible to examine real-world driving using naturalistic data obtained from in-vehicle monitoring devices. These devices overcome the weaknesses of self-report methods and can provide comprehensive insights into driving exposure, habits and practices of older drivers. Aim: The aim of this study is to compare self-reported and objectively measured driving exposure, habits and practices using a travel diary and an in-vehicle driver monitoring device in older drivers with bilateral cataract. Methods: A cross-sectional study was undertaken. Forty seven participants aged 58-89 years old (mean. =74.1; S.D. =7.73) were recruited from three eye clinics over a one year period. Data collection consisted of a cognitive test, a researcher-administered questionnaire, a travel diary and an in-vehicle monitoring device. Participants' driving exposure and patterns were recorded for one week using in-vehicle monitoring devices. They also completed a travel diary each time they drove a motor vehicle as the driver. Paired t-tests were used to examine differences/agreement between the two instruments under different driving circumstances. Results: The data from the older drivers' travel diaries significantly underestimated the number of overall trips (p < 0.001), weekend trips (p. =0.002) and trips during peak hour (p. =0.004). The travel diaries also significantly overestimated overall driving duration (p. &lt;. 0.001) and weekend driving duration (p. =0.003), compared to the data obtained from the in-vehicle monitoring devices. No significant differences were found between instruments for kilometres travelled under any of the driving circumstances.Conclusions: The results of this study found that relying solely on self-reported travel diaries to assess driving outcomes may not be accurate, particularly for estimates of the number of trips made and duration of trips. The clear advantages of using in-vehicle monitoring devices over travel diaries to monitor driving habits and exposure among an older population are evident