Cavity Optomechanics with a Laser Engineered Optical Trap

Laser engineered exciton-polariton networks could lead to dynamically configurable integrated optical circuitry and quantum devices. Combining cavity optomechanics with electrodynamics in laser configurable hybrid designs constitutes a platform for the vibrational control, conversion, and transport of signals. With this aim we investigate 3D optical traps laser-induced in quantum-well embedded semiconductor planar microcavities. We show that the laser generated and controlled discrete states of the traps dramatically modify the interaction between photons and phonons confined in the resonators, accessing through coupling of photoelastic origin $g_\mathrm{0}/2\pi\sim 1.7$ MHz an optomechanical cooperativity $C>1$ for mW excitation. The quenching of Stokes processes and double-resonant enhancement of anti-Stokes ones involving pairs of discrete optical states in the side-band resolved regime, allows the optomechanical cooling of 180 GHz bulk acoustic waves, starting from room temperature down to $\sim120$ K. These results pave the way for dynamical tailoring of optomechanical actuation in the extremely-high-frequency range (30-300 GHz) for future network and quantum technologies.Comment: 22 pages, 14 figure

Shedding of endothelial protein C receptor contributes to vasculopathy and renal injury in lupus: In vivo and in vitro evidence1

Shedding of endothelial protein C receptor contributes to vasculopathy and renal injury in lupus: In vivo and in vitro evidence.BackgroundCandidate biomarkers for vasculopathy in systemic lupus erythematosus (SLE) include circulating endothelial cells and the recently identified endothelial protein C receptor (EPCR) which, when shed, promotes a thrombotic diathesis. This study sought correlation between plasma levels of soluble EPCR and disease manifestation/severity, with a focus on lupus nephritis.MethodsIn 81 SLE patients (evaluated cross-sectionally and longitudinally) and 59 healthy controls, levels of soluble EPCR and soluble E-selectin were assessed by sandwich enzyme-linked immunosorbent assay (ELISA), circulating endothelial cells isolated by immunomagnetic separation, and EPCR gene polymorphisms determined. Mechanisms of vascular injury were addressed in vitro in human aortic endothelial cells (HAEC) cultured in the presence and absence of interferon-γ (IFN-γ).ResultsThe mean level of soluble EPCR was significantly higher in SLE patients (263 ± 13ng/mL) than controls (174 ± 11ng/mL) (P < 0.0001). Patients with active or past renal involvement had significantly higher mean soluble EPCR levels (306 ± 21ng/mL) (N = 40) than patients without nephritis (228 ± 14ng/mL) (N = 41) (P = 0.0033). Mean soluble EPCR correlated positively with serum creatinine (R = 0.3429, P < 0.0001). The prevalence of the enhanced-shedding EPCR polymorphism A6936G was higher in SLE (41%) (N = 27) than controls (7%) (N = 29) (P = 0.0039). Patient and control plasma were also interrogated for soluble E-selectin, a comparator plasma marker. The results suggest that soluble E-selectin and soluble EPCR are not equivalent end points of vasculopathy and endothelial perturbation in SLE. Although in SLE patients the absence or diminished expression of membrane EPCR on circulating endothelial cells varied, the rare circulating endothelial cells detected in controls invariably expressed membrane-bound EPCR. IFN-γ-treated HAEC expressed less membrane-bound EPCR [133 relative fluorescence units (rfu)] than untreated HAEC (275 rfu); more soluble EPCR was detected in IFN-γ-treated (1.1ng/106 cells) than untreated HAEC (0.65ng/106 cells) (P = 0.027).ConclusionThe results obtained from this cross-sectional/longitudinal study support the hypothesis that the vascular dysfunction characteristic of SLE may be related to a dramatically altered distribution of EPCR, both soluble and membrane-bound forms

Scaling rules in optomechanical semiconductor micropillars

International audienceSemiconductor pillar microcavities have recently emerged as a promising optomechanical platform in the unprecedented 20-GHz frequency range. Currently established models for the mechanical behavior of micropillars, however, rely on complete numerical simulations or semianalytical approaches, which makes their application to experiments notoriously difficult. Here we overcome this challenge with an effective model by reducing the full, hybridized mechanical mode picture of a micropillar to an approach that captures the observed global trends. We show experimentally the validity of this approach by studying the lateral size dependence of the frequency, amplitude, and lifetime of the mechanical modes of square-section pillar microcavities, using room-temperature pump-probe microscopy. General scaling rules for these quantities are found and explained through simple phenomenological models of the physical phenomena involved. We show that the energy shift ω m of the modes due to confinement is dependent on the inverse of their frequency ω 0 and lateral size L (ω m ∝ 1/ω 0 L 2) and that the mode lifetime τ is linear with pillar size and inversely proportional to their frequency (τ ∝ L/ω 0). The mode amplitude is in turn inversely proportional to the lateral size of the considered resonators. This is related to the dependence of the optomechanical coupling rate (g 0 ∝ 1/L) with the spatial extent of the confined electromagnetic and mechanical fields. Using a numerical model based on the finite-element method, we determine the magnitude and size dependence of g 0 and, by combining the results with the experimental data, we discuss the attainable single-photon cooperativity in these systems. The effective models proposed and the scaling rules found constitute an important tool in micropillar optomechanics and in the future development of more complex micropillar based devices

Applying science in practice: the optimization of biological therapy in rheumatoid arthritis

Most authorities recommend starting biological agents upon failure of at least one disease-modifying agent in patients with rheumatoid arthritis. However, owing to the absence of head-to-head studies, there is little guidance about which biological to select. Still, the practicing clinician has to decide. This review explores the application of published evidence to practice, discussing the goals of treatment, the (in) ability to predict individual responses to therapy, and the potential value of indirect comparisons. We suggest that cycling of biological agents, until remission is achieved or until the most effective agent for that individual patient is determined, deserves consideration in the current stage of knowledge

Severe plastic deformation for producing superfunctional ultrafine-grained and heterostructured materials: An interdisciplinary review

Ultrafine-grained and heterostructured materials are currently of high interest due to their superior mechanical and functional properties. Severe plastic deformation (SPD) is one of the most effective methods to produce such materials with unique microstructure-property relationships. In this review paper, after summarizing the recent progress in developing various SPD methods for processing bulk, surface and powder of materials, the main structural and microstructural features of SPD-processed materials are explained including lattice defects, grain boundaries and phase transformations. The properties and potential applications of SPD-processed materials are then reviewed in detail including tensile properties, creep, superplasticity, hydrogen embrittlement resistance, electrical conductivity, magnetic properties, optical properties, solar energy harvesting, photocatalysis, electrocatalysis, hydrolysis, hydrogen storage, hydrogen production, CO2 conversion, corrosion resistance and biocompatibility. It is shown that achieving such properties is not limited to pure metals and conventional metallic alloys, and a wide range of materials are currently processed by SPD, including high-entropy alloys, glasses, semiconductors, ceramics and polymers. It is particularly emphasized that SPD has moved from a simple metal processing tool to a powerful means for the discovery and synthesis of new superfunctional metallic and nonmetallic materials. The article ends by declaring that the borders of SPD have been extended from materials science and it has become an interdisciplinary tool to address scientific questions such as the mechanisms of geological and astronomical phenomena and the origin of life