Broad Diversity of Near-Infrared Single-Photon Emitters in Silicon.

We report the detection of individual emitters in silicon belonging to seven different families of optically active point defects. These fluorescent centers are created by carbon implantation of a commercial silicon-on-insulator wafer usually employed for integrated photonics. Single photon emission is demonstrated over the 1.1-1.55 µm range, spanning the O and C telecom bands. We analyze their photoluminescence spectra, dipolar emissions, and optical relaxation dynamics at 10 K. For a specific family, we show a constant emission intensity at saturation from 10 K to temperatures well above the 77 K liquid nitrogen temperature. Given the advanced control over nanofabrication and integration in silicon, these individual artificial atoms are promising systems to investigate for Si-based quantum technologies.

Strain-Gradient Position Mapping of Semiconductor Quantum Dots.

We introduce a nondestructive method to determine the position of randomly distributed semiconductor quantum dots (QDs) integrated in a solid photonic structure. By setting the structure in an oscillating motion, we generate a large stress gradient across the QDs plane. We then exploit the fact that the QDs emission frequency is highly sensitive to the local material stress to map the position of QDs deeply embedded in a photonic wire antenna with an accuracy ranging from ±35 nm down to ±1 nm. In the context of fast developing quantum technologies, this technique can be generalized to different photonic nanostructures embedding any stress-sensitive quantum emitters.

Harvesting, Coupling, and Control of Single-Exciton Coherences in Photonic Waveguide Antennas.

We perform coherent nonlinear spectroscopy of individual excitons strongly confined in single InAs quantum dots (QDs). The retrieval of their intrinsically weak four-wave mixing (FWM) response is enabled by a one-dimensional dielectric waveguide antenna. Compared to a similar QD embedded in bulk media, the FWM detection sensitivity is enhanced by up to 4 orders of magnitude, over a broad operation bandwidth. Three-beam FWM is employed to investigate coherence and population dynamics within individual QD transitions. We retrieve their homogenous dephasing in a presence of low-frequency spectral wandering. Two-dimensional FWM reveals off-resonant Förster coupling between a pair of distinct QDs embedded in the antenna. We also detect a higher order QD nonlinearity (six-wave mixing) and use it to coherently control the FWM transient. Waveguide antennas enable us to conceive multicolor coherent manipulation schemes of individual emitters.

[Myringoplasties for anterior tympanic perforations: Our surgical technique]. / Myringoplastie pour les perforations tympaniques antérieures: notre technique opératoire.

Anterior tympanic perforations are actually the most difficult to close and a number of different techniques exist. This article represents the author's surgical procedure for type I tympanoplasties (myringoplasties) for this kind of perforation using the tragal cartilage and the perichondrium after preparation (revival, cleaning) of the perforation edge with a laser. This technique does not use a skin incision of external auditory meatus, when this one is large.

[Reconstruction of bone defects in the earcanal with hydroxyapatite]. / Reconstruction des defects osseux du conduit auditif externe par ciment d'hydroxyapatite.

Traditional reconstruction methods of osseous defects within the tympanic frame, most often being the atticotomy, within the framework of chronic otitis media surgery, still do not produce stable or definitive results, usually due to displacement or partial lyse of the transplanted material (cartilage, bone ...). The reconstruction procedure with the aid of hydroxyapatite cement as presented by the authors, allows for a complete, stable and definitive reconstruction.

Cochlear implantation in advanced otosclerosis: utility of pre-operative radiological assessment in predicting intra-operative difficulty and final electrode position.

OBJECTIVE: This study aimed to determine if pre-operative radiological scoring can reliably predict intra-operative difficulty and final cochlear electrode position in patients with advanced otosclerosis. METHOD: A retrospective cohort study of advanced otosclerosis patients who underwent cochlear implantation (n = 48, 52 ears) was compared with a larger cohort of post-lingually deaf adult patients (n = 1414) with bilateral hearing loss and normal cochlear anatomy. Pre-operative imaging for advanced otosclerosis patients and final electrode position were scored and correlated with intra-operative difficulty and speech outcomes. RESULTS: Advanced otosclerosis patients benefit significantly from cochlear implantation. Mean duration of deafness was longer in the advanced otosclerosis group (19.5 vs 14.3 years; p < 0.05). CONCLUSION: Anatomical changes in advanced otosclerosis can result in increased difficulty of surgery. Evidence of pre-operative cochlear luminal changes was associated with intra-operative difficult insertion and final non-scala tympani position. Nearly all electrodes implanted in the advanced otosclerosis cohort were peri-modiolar. No reports of facial nerve stimulation were observed.

Shared genetic etiology between Parkinson's disease and blood levels of specific lipids.

Parkinson's disease (PD) is characterized by the degeneration of dopaminergic neurons in the substantia nigra and the formation of Lewy bodies. The mechanisms underlying these molecular and cellular effects are largely unknown. Previously, based on genetic and other data, we built a molecular landscape of PD that highlighted a central role for lipids. To explore which lipid species may be involved in PD pathology, we used published genome-wide association study (GWAS) data to conduct polygenic risk score-based analyses to examine putative genetic sharing between PD and blood levels of 370 lipid species and lipid-related molecules. We found a shared genetic etiology between PD and blood levels of 25 lipids. We then used data from a much-extended GWAS of PD to try and corroborate our findings. Across both analyses, we found genetic overlap between PD and blood levels of eight lipid species, namely two polyunsaturated fatty acids (PUFA 20:3n3-n6 and 20:4n6), four triacylglycerols (TAG 44:1, 46:1, 46:2, and 48:0), phosphatidylcholine aa 32:3 (PC aa 32:3) and sphingomyelin 26:0 (SM 26:0). Analysis of the concordance-the agreement in genetic variant effect directions across two traits-revealed a significant negative concordance between PD and blood levels of the four triacylglycerols and PC aa 32:3 and a positive concordance between PD and blood levels of both PUFA and SM 26:0. Taken together, our analyses imply that genetic variants associated with PD modulate blood levels of a specific set of lipid species supporting a key role of these lipids in PD etiology.

Imaging the wave-function amplitudes in cleaved semiconductor quantum boxes

We have investigated the electronic structure of the conduction band states in InAs quantum boxes embedded in GaAs. Using cross-sectional scanning tunneling microscopy and spectroscopy, we report the direct observation of standing wave patterns in the boxes at room temperature. Electronic structure calculation of similar cleaved boxes allows the identification of the standing waves pattern as the probability density of the ground and first excited states. Their spatial distribution in the (001) plane is significantly affected by the strain relaxation due to the cleavage of the boxes.

Strain-mediated coupling in a quantum dot-mechanical oscillator hybrid system.

Recent progress in nanotechnology has allowed the fabrication of new hybrid systems in which a single two-level system is coupled to a mechanical nanoresonator. In such systems the quantum nature of a macroscopic degree of freedom can be revealed and manipulated. This opens up appealing perspectives for quantum information technologies, and for the exploration of the quantum-classical boundary. Here we present the experimental realization of a monolithic solid-state hybrid system governed by material strain: a quantum dot is embedded within a nanowire that features discrete mechanical resonances corresponding to flexural vibration modes. Mechanical vibrations result in a time-varying strain field that modulates the quantum dot transition energy. This approach simultaneously offers a large light-extraction efficiency and a large exciton-phonon coupling strength g0. By means of optical and mechanical spectroscopy, we find that g0/2 π is nearly as large as the mechanical frequency, a criterion that defines the ultrastrong coupling regime.

Twisted custodial symmetry in two-Higgs-doublet models.

In the standard model for electroweak interactions, the Higgs sector is known to display a custodial symmetry protecting the mass relation m(W(+/-))(2) = m(W(3))(2) from large corrections. When considering extensions of the scalar sector, this symmetry has to be introduced by hand in order to pass current electroweak precision tests in a natural way. In this Letter, we implement a generalized custodial symmetry in the two-Higgs-doublet model. Assuming the invariance of the potential under CP transformations, we prove the existence of a new custodial scenario characterized by m(H(+/-))(2) = m(H(0))(2) instead of m(H(+/-))(2) = m(A(0))(2). Consequently, the pseudoscalar A(0) may be much lighter than the charged H(+/-), giving rise to interesting phenomenology.

Anomalous enhancement of a penguin hadronic matrix element in B-->K(eta').

We estimate the density matrix element for the pi(0), eta, and eta(') production from the vacuum in the large-N(c) limit. As a consequence, we find that the QCD axial anomaly leads to highly nontrivial corrections to the usual flavor SU(3) relations between B(0)-->K(0)pi(0), B(0)-->K(0) eta, and B(0)-->K(0)eta(') decay amplitudes. These corrections may explain why the B-->Keta(') branching ratio is about 6 times larger than the B-->Kpi one.

Optically driven spin memory in n-doped InAs-GaAs quantum dots.

We show that the spin state of the resident electron in an n-doped self-assembled InAs-GaAs quantum dot can be written and read using nonresonant, circularly polarized optical pumping. A simple theoretical model is presented and accounts for the remarkable dynamics producing counterpolarized photoluminescence.

Long polaron lifetime in InAs/GaAs self-assembled quantum dots.

We have investigated the polaron dynamics in n-doped InAs/GaAs self-assembled quantum dots by pump-probe midinfrared spectroscopy. A long T1 polaron decay time is measured at both low temperature and room temperature, with values around 70 and 37 ps, respectively. The decay time decreases for energies closer to the optical phonon energy. The relaxation is explained by the strong coupling for the electron-phonon interaction and by the finite lifetime of the optical phonons. We show that, even for a large detuning of 19 meV from the LO photon energy in GaAs, the carrier relaxation remains phonon assisted.

Pyrenochaeta keratinophila sp. nov., isolated from an ocular infection in Spain

Se describe e ilustra el nuevo celomicete Pyrenochaeta keratinophila, aislado de un raspado corneal procedente de un caso de queratitis en España. Este hongo se caracteriza morfológicamente por tener colonias de color gris oliváceo a verdoso, setas picnidiales escasas principalmente situadas cerca del ostiolo, y producir conidios fialídicos a partir del micelio aéreo. Este último carácter no se ha observado en ninguna otra especie del género Pyrenochaeta. La secuencia de la región ITS de ADNr de esta cepa clínica confirma nuestra propuesta y pone de manifiesto su estrecha relación con la familia Leptosphaeriaceae(AU)

The new coelomycete Pyrenochaeta keratinophila, isolated from corneal scrapings of a case of keratitis in Spain, is described and illustrated. This fungus is morphologically characterized by grey-olivaceous to greenish olivaceous colonies, scarce pycnidial setae placed mainly near the ostiole and production of phialoconidia from the aerial mycelium. The latter feature is unknown in any other species of the genus Pyrenochaeta. Sequencing of the ITS rDNA region of this clinical strain confirmed this proposal and revealed its close genetic relationship with the Leptosphaeriaceae