High Q-factor near infrared and visible Al2O3-based parallel-plate capacitor kinetic inductance detectors.

We designed, fabricated and characterized parallel-plate capacitor lumped-element kinetic inductance detectors (LEKIDs) to operate at near-infrared and optical wavelengths (0.3 -1 µm). The widely used interdigitated capacitor is replaced by a parallel-plate capacitor which, for a given resonance frequency, has a larger capacitance value within a much smaller space allowing to strongly reduce the size of the pixels. The parallel-plate capacitor LEKID array comprises 10 × 10 pixels. The inductive meander is patterned from stoichiometric 52 nm-thick TiN film (Tc ≈4.6 K). The parallel-plate capacitor is made of a TiN base electrode, Al2O3 dielectric and Nb upper electrode. More than 90 resonances out of 100 within the 0.994-1.278 GHz band were identified. The resonances exhibit internal Q-factors up to ∼370 000 at 72 mK. The array was illuminated using a white light and 890 nm monochromatic near infrared LEDs. The estimated quasiparticle lifetime is τqp≈13 µs.

Loss Mechanisms and Quasiparticle Dynamics in Superconducting Microwave Resonators Made of Thin-Film Granular Aluminum.

Superconducting high kinetic inductance elements constitute a valuable resource for quantum circuit design and millimeter-wave detection. Granular aluminum (grAl) in the superconducting regime is a particularly interesting material since it has already shown a kinetic inductance in the range of nH/□ and its deposition is compatible with conventional Al/AlOx/Al Josephson junction fabrication. We characterize microwave resonators fabricated from grAl with a room temperature resistivity of 4×10^{3} µΩ cm, which is a factor of 3 below the superconductor to insulator transition, showing a kinetic inductance fraction close to unity. The measured internal quality factors are on the order of Q_{i}=10^{5} in the single photon regime, and we demonstrate that nonequilibrium quasiparticles (QPs) constitute the dominant loss mechanism. We extract QP relaxation times in the range of 1 s and we observe QP bursts every ∼20 s. The current level of coherence of grAl resonators makes them attractive for integration in quantum devices, while it also evidences the need to reduce the density of nonequilibrium QPs.

Cystoid macular edema after pars plana vitrectomy for idiopathic epiretinal membrane.

BACKGROUND: To evaluate the incidence of cystoid macular edema (CME) after 23-gauge pars plana vitrectomy (PPV) with or without combined cataract surgery for the treatment of idiopathic epiretinal membrane (ERM). METHODS: Retrospective, non-comparative, interventional case series. Data included patient age, indication for surgery, and intra- and post-operative complications. The follow-up lasted 1 year. Best-corrected visual acuity (BCVA logMAR), central foveal thickness (CFT micron-µ) and the incidence of intra-retinal cysts were evaluated. CME was defined as post-operative observation of intra-retinal cysts at optical coherence tomography, preventing improvement or causing reduction of BCVA when compared to the pre-operative value. Statistical analysis was performed to identify the risk factors of CME. RESULTS: Two hundred and forty two eyes of 242 patients underwent PPV for the treatment of idiopathic ERM. Statistical analysis showed that the presence of preoperative intra-retinal cysts were associated with persistent CME following surgery (odds ratio 3.89; 95%CI: 1.63-9.28, P = 0.0004). However, postoperative CME occurred in 10 % of eyes that did not show preoperative CME. In addition, there was a significant correlation between the baseline value of CFT and the values of CFT at each time point during the follow up (p < 0.0001), with greater values of the pre-operative thickness correlating to greater values of post-operative thickness. CONCLUSIONS: Persistent or new CME following surgery for idiopathic ERM are frequently identified after PPV for ERM. The statistical results of the current study suggest that intraretinal cysts and increased preoperative CFT are associated with reduced visual acuity after surgery.

Intracameral cefuroxime in combined pars plana vitrectomy and phacoemulsification: a study of safety.

BACKGROUND: Postoperative endophthalmitis is a severe complication after intraocular surgery. The aim of this pilot study was to investigate the safety of intracameral cefuroxime in combined vitrectomy and phacoemulsification for cataract and various vitreoretinal disease. METHODS: The charts of 152 patients who underwent combined phacoemulsification, intraocular lens implant and pars plana vitrectomy were reviewed. The final tamponade was chosen among fluid, air, gas or silicone oil, based on the requirement of each single case. Patients were operated on by four different surgeons. At the end of surgery, 1 mg/0.1 mL of intracameral cefuroxime (Aprokam) was administered. RESULTS: The mean follow-up was 6.26±7.78 months (range 1-12). No retinal complication, such as retinal infarction or hemorrhages were observed. No acute macular serous detachment and no new intraretinal cysts were noted, in those patients who received optical coherence tomography within the fifth day after surgery. No endophthalmitis was recorded. CONCLUSION: Intracameral cefuroxime, at the end of combined phacoemulsification and pars plana vitrectomy, is safe as it has no toxicity on the retina and maybe could be considered effective in endophthalmitis prevention. Due to the relatively small number of patients, further studies are advisable. SUMMARY STATEMENT: The standard dose of intracameral cefuroxime at the end of combined phacoemulsification and pars plana vitrectomy has no toxic effects on the retina. This paper/The abstract of this paper was presented at the European Vitreo Retinal Society Conference 2017 as a conference talk with interim findings. The poster's abstract was not published.

Early optical polarization of a gamma-ray burst afterglow.

We report the optical polarization of a gamma-ray burst (GRB) afterglow, obtained 203 seconds after the initial burst of gamma-rays from GRB 060418, using a ring polarimeter on the robotic Liverpool Telescope. Our robust (2sigma) upper limit on the percentage of polarization, less than 8%, coincides with the fireball deceleration time at the onset of the afterglow. The combination of the rate of decay of the optical brightness and the low polarization at this critical time constrains standard models of GRB ejecta, ruling out the presence of a large-scale ordered magnetic field in the emitting region.