Anderson localisation in steady states of microcavity polaritons

We present an experimental signature of the Anderson localisation of microcavity polaritons, and provide a systematic study of the dependence on disorder strength. We reveal a controllable degree of localisation, as characterised by the inverse-participation ratio, by tuning the positional disorder of arrays of interacting mesas. This constitutes the realisation of disorder-induced localisation in a driven-dissipative system. In addition to being an ideal candidate for investigating localisation in this regime, microcavity polaritons hold promise for low-power, ultra-small devices and their localisation could be used as a resource in quantum memory and quantum information processing.Comment: 7 pages, 3 figure

Intertwining of Zeeman and Coulomb interactions on excitons in highly symmetric semiconductor quantum dots

We present an experimental study and develop a group theoretical analysis of the Zeeman effect on excitons in pyramidal semiconductor quantum dots possessing the symmetries of the C3v point group. The magnetic field dependence of the emission pattern originating from neutral exciton states is investigated in both the Faraday and Voigt configurations. The Zeeman doublet splitting of the “bright” exciton states varies linearly with the magnetic field strength in each configuration while the intensity of the “dark” exciton transitions exhibit a nonlinear dependence. We demonstrate that these observations originate from the intertwining of the Zeeman and Coulomb interactions, which provides clear spectral signatures of this effect for highly symmetric quantum dots. We uncover a large anisotropy of the Zeeman doublet splittings for longitudinal and transverse magnetic fields, revealing the ubiquitous role of a symmetry elevation in our pyramidal quantum dots. These results suggest that the common description of the Zeeman effect based on effective g factors for electrons and holes must be revised when dealing with exciton complexes

Dephasing effects on coherent exciton-polaritons and the breakdown of the strong coupling regime

International audienceUsing femtosecond pump-probe spectroscopy, we identify excitation-induced dephasing as a major mechanism responsible for the breakdown of the strong coupling between excitons and photons in a semiconductor microcavity. The effects of dephasing are observed on the transmitted probe-pulse spectrum as a density-dependent broadening of the exciton-polariton resonances and the emergence of a third resonance at high excitation density. A striking asymmetry in the energy shift between the upper and the lower polaritons is also evidenced. Using the excitonic Bloch equations, we quantify the respective contributions to the energy shift of many-body effects associated with Coulomb fermion exchange and photon assisted exchange processes and the contribution to collisional broadening

Finite Element Model to Study the Deformations of Nb3_{3}Sn Wires for the Next European Dipole (NED)

The Next European Dipole (NED) activity is aimed at the development of a large-aperture, high-field superconducting magnet relying on high-performances Nb$_{3}$Sn conductors. Part of the NED program is devoted to the mechanical study of a new generation of Nb$_{3}$Sn wires and to predict and describe their behavior under the severe loading conditions of the cabling process. The deformation resulting from the cabling process was simulated through mechanical analyses by Finite Elements (FE). The ensuing results of FE analyses are presented, allowing the wire behavior under simple uni-axial loads to be described. They are compared to cross section micrographs of deformed wires

The trajectory of anti-recEm18 antibody levels determines follow-up after curative resection of hepatic alveolar echinococcosis.

INTRODUCTION Recurrence after curative resection of hepatic alveolar echinococcosis remains a clinical challenge. The current study tested if assessment of anti-recEm18 allows for postsurgical patient surveillance. METHODS A retrospective study with patients undergoing liver resection for alveolar echinococcosis (n = 88) at the University Hospital Bern from 2002 to 2020 and at the University Hospital and Medical Center Ulm from 2011 to 2017 was performed. Analysis was directed to determine a potential association of pre- and postoperative values of anti-recEm18 with clinical outcomes. RESULTS Anti-recEm18 had a linear correlation to the maximum lesion diameter (R2 = 0.558). Three trajectories of anti-recEm18 were identified based on a threshold of 10 AU/ml: "Em18-low" (n = 31), "responders" (n = 53) and "residual disease" (n = 4). The decline of anti-recEm18 in "responders" reached a plateau after 10.9 months at which levels decreased by 90%. The only patient with recurrence in the entire population was also the only patient with a secondary increase of anti-recEm18. CONCLUSION In patients with preoperative elevated values, anti-recEm18 confirms curative surgery at 12 months follow-up and allows for long-term surveillance

Full potential LAPW calculation of electron momentum density and related properties of Li

Electron momentum density and Compton profiles in Lithium along $$,$$, and $$ directions are calculated using Full-Potential Linear Augmented Plane Wave basis within generalized gradient approximation. The profiles have been corrected for correlations with Lam-Platzman formulation using self-consistent charge density. The first and second derivatives of Compton profiles are studied to investigate the Fermi surface breaks. Decent agreement is observed between recent experimental and our calculated values. Our values for the derivatives are found to be in better agreement with experiments than earlier theoretical results. Two-photon momentum density and one- and two-dimensional angular correlation of positron annihilation radiation are also calculated within the same formalism and including the electron-positron enhancement factor.Comment: 11 pages, 7 figures TO appear in Physical Review

Rapid, Single-Cell Analysis and Discovery of Vectored mRNA Transfection In Vivo with a loxP-Flanked tdTomato Reporter Mouse

mRNA therapeutics hold promise for the treatment of diseases requiring intracellular protein expression and for use in genome editing systems, but mRNA must transfect the desired tissue and cell type to be efficacious. Nanoparticle vectors that deliver the mRNA are often evaluated using mRNA encoding for reporter genes such as firefly luciferase (FLuc); however, single-cell resolution of mRNA expression cannot generally be achieved with FLuc, and, thus, the transfected cell populations cannot be determined without additional steps or experiments. To more rapidly identify which types of cells an mRNA formulation transfects in vivo, we describe a Cre recombinase (Cre)-based system that permanently expresses fluorescent tdTomato protein in transfected cells of genetically modified mice. Following in vivo application of vectored Cre mRNA, it is possible to visualize successfully transfected cells via Cre-mediated tdTomato expression in bulk tissues and with single-cell resolution. Using this system, we identify previously unknown transfected cell types of an existing mRNA delivery vehicle in vivo and also develop a new mRNA formulation capable of transfecting lung endothelial cells. Importantly, the same formulations with mRNA encoding for fluorescent protein delivered to wild-type mice did not produce sufficient signal for any visualization in vivo, demonstrating the significantly improved sensitivity of our Cre-based system. We believe that the system described here may facilitate the identification and characterization of mRNA delivery vectors to new tissues and cell types

A spiral scaffold underlies cytoadherent knobs in Plasmodium falciparum-infected erythrocytes

Much of the virulence of Plasmodium falciparum malaria is caused by cytoadherence of infected erythrocytes, which promotes parasite survival by preventing clearance in the spleen. Adherence is mediated by membrane protrusions known as knobs, whose formation depends on the parasite-derived, knob-associated histidine-rich protein (KAHRP). Knobs are required for cytoadherence under flow conditions, and they contain both KAHRP and the parasite-derived erythrocyte membrane protein PfEMP1. Using electron tomography, we have examined the three-dimensional structure of knobs in detergent-insoluble skeletons of P. falciparum 3D7 schizonts. We describe a highly organised knob skeleton composed of a spiral structure coated by an electron dense layer underlying the knob membrane. This knob skeleton is connected by multiple links to the erythrocyte cytoskeleton. We used immuno-electron microscopy to locate KAHRP in these structures. The arrangement of membrane proteins in the knobs, visualised by high resolution freeze fracture scanning electron microscopy, is distinct from that in the surrounding erythrocyte membrane, with a structure at the apex that likely represents the adhesion site. Thus, erythrocyte knobs in P. falciparum infection contain a highly organised skeleton structure underlying a specialised region of membrane. We propose that the spiral and dense coat organise the cytoadherence structures in the knob, and anchor them into the erythrocyte cytoskeleton. The high density of knobs and their extensive mechanical linkage suggest an explanation for the rigidification of the cytoskeleton in infected cells, and for the transmission to the cytoskeleton of shear forces experienced by adhering cells