Shaft Resistance During Driving in Clay from Laboratory Tests

This paper presents a laboratory study which aimed at investigating the soil/pile interaction during driving. A short review of past experimental works justifies the need for more consistent data. The test equipment (a rod driven through a sample of soil) is briefly presented and some signals are displayed to illustrate the quality of the measurements. The tests were performed on samples of normally consolidated Kaolinit clay. The analysis of the stress waves propagating in the rod, during driving, provided a good estimation of interaction forces, bar velocities and displacements of the pile model in the sample. Relationships were established between the interaction force, the energy dissipated in the sample of soil, the velocity and the displacement of the rod, and the confining pressure of the sample. Observations and relationships were used (1) to identify the physical phenomena occurring at the soil/pile interface during driving, and (2) to base a law governing this shaft interaction

ICP polishing of silicon for high quality optical resonators on a chip

Miniature concave hollows, made by wet etching silicon through a circular mask, can be used as mirror substrates for building optical micro-cavities on a chip. In this paper we investigate how ICP polishing improves both shape and roughness of the mirror substrates. We characterise the evolution of the surfaces during the ICP polishing using white-light optical profilometry and atomic force microscopy. A surface roughness of 1 nm is reached, which reduces to 0.5 nm after coating with a high reflectivity dielectric. With such smooth mirrors, the optical cavity finesse is now limited by the shape of the underlying mirror

Gamma-irradiated human amniotic membrane decellularised with sodium dodecyl sulfate is a more efficient substrate for the ex vivo expansion of limbal stem cells

yesThe gold standard substrate for the ex vivo expansion of human limbal stem cells (LSCs) remains the human amniotic membrane (HAM) but this is not a defined substrate and is subject to biological variabil-ity and the potential to transmit disease. To better define HAM and mitigate the risk of disease transmis-sion, we sought to determine if decellularisation and/or c-irradiation have an adverse effect on culture growth and LSC phenotype. Ex vivo limbal explant cultures were set up on fresh HAM, HAM decellularised with 0.5 M NaOH, and 0.5% (w/v) sodium dodecyl sulfate (SDS) with or without c-irradiation. Explant growth rate was measured and LSC phenotype was characterised by histology, immunostaining and qRT-PCR (ABCG2, DNp63, Ki67, CK12, and CK13). Ƴ-irradiation marginally stiffened HAM, as measured by Brillouin spectromicroscopy. HAM stiffness and c-irradiation did not significantly affect the LSC phe-notype, however LSCs expanded significantly faster on Ƴ-irradiated SDS decellularised HAM (p < 0.05) which was also corroborated by the highest expression of Ki67 and putative LSC marker, ABCG2. Colony forming efficiency assays showed a greater yield and proportion of holoclones in cells cultured on Ƴ-irradiated SDS decellularised HAM. Together our data indicate that SDS decellularised HAM may be a more efficacious substrate for the expansion of LSCs and the use of a c-irradiated HAM allows the user to start the manufacturing process with a sterile substrate, potentially making it safer

Out-of-equilibrium physics in driven dissipative coupled resonator arrays

Coupled resonator arrays have been shown to exhibit interesting many- body physics including Mott and Fractional Hall states of photons. One of the main differences between these photonic quantum simulators and their cold atoms coun- terparts is in the dissipative nature of their photonic excitations. The natural equi- librium state is where there are no photons left in the cavity. Pumping the system with external drives is therefore necessary to compensate for the losses and realise non-trivial states. The external driving here can easily be tuned to be incoherent, coherent or fully quantum, opening the road for exploration of many body regimes beyond the reach of other approaches. In this chapter, we review some of the physics arising in driven dissipative coupled resonator arrays including photon fermionisa- tion, crystallisation, as well as photonic quantum Hall physics out of equilibrium. We start by briefly describing possible experimental candidates to realise coupled resonator arrays along with the two theoretical models that capture their physics, the Jaynes-Cummings-Hubbard and Bose-Hubbard Hamiltonians. A brief review of the analytical and sophisticated numerical methods required to tackle these systems is included.Comment: Chapter that appeared in "Quantum Simulations with Photons and Polaritons: Merging Quantum Optics with Condensed Matter Physics" edited by D.G.Angelakis, Quantum Science and Technology Series, Springer 201

Photon condensation in circuit QED by engineered dissipation

We study photon condensation phenomena in a driven and dissipative array of superconducting microwave resonators. Specifically, we show that by using an appropriately designed coupling of microwave photons to superconducting qubits, an effective dissipative mechanism can be engineered, which scatters photons towards low-momentum states while conserving their number. This mimics a tunable coupling of bosons to a low temperature bath, and leads to the formation of a stationary photon condensate in the presence of losses and under continuous-driving conditions. Here we propose a realistic experimental setup to observe this effect in two or multiple coupled cavities, and study the characteristics of such an out-of-equilibrium condensate, which arise from the competition between pumping and dissipation processes

Pertinence d’essais sur modèle réduit en centrifugeuse pour l’étude du comportement d’un silo métallique céréalier

L'article présente les résultats d'une série d'expériences faites sur un modèle réduit en centrifugeuse, à l'échelle 1/10e, d'un silo à céréales. La comparaison entre les observations faites sur l'ouvrage grandeur réelle et celles obtenues sur le modèle permet d'apprécier la valeur de la modélisation et les perspectives ouvertes par les essais sur modèles en centrifugeuse pour l'étude des silos et des écoulements en milieu granulaire

Demonstration of UV-written waveguides, Bragg gratings and cavities at 780 nm, and an original experimental measurement of group delay

We present direct UV-written waveguides and Bragg gratings operating at 780 nm. By combining two gratings into a Fabry-Perot cavity we have devised and implemented a novel and practical method of measuring the group delay of Bragg gratings