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Silicon photonics has emerged as a very promising technology platform for the implementation of high-performance, low-cost, ultra-compact circuits that can monolithically cointegrate electronic, opto-electronic and optic functionalities. However, Si neither has efficient light emission or detection in the telecom wavelength range, nor exhibits efficient electro-optic Pockels effect, hindering the implementation of integrated active devices like sources, detectors, or modulators. Current approaches relay on different materials to provide active functionalities in Si photonics, resulting in highly complex integration schemes that compromise cost-effectiveness. Semiconducting single-wall carbon nanotubes (SWNTs) are capable of emitting and detecting near-infrared light at room temperature and exhibit intrinsically fast electro-optic effects. They have also proven promising uses in micro-electronic devices, making them an ideal material to provide active functionalities in the Si photonic platform. In this work, we propose and experimentally validate the possible use of slot photonic waveguides to improve interaction between SWNTs and Si waveguide modes. Fabricated Si slot micro-ring shown an experimental similar to 60% photo-luminescence improvement compared to previous demonstration based on Si strip waveguide resonators. These results prove the potential of Si slot waveguides for the implementation of efficient SWNT-based Si photonic devices.

Background Since its approval, the use of alteplase had been limited to patients aged ≤80 years. Aims TESPI trial had been designed to evaluate whether alteplase treatment within 3 h in patients with acute ischemic stroke aged >80 years resulted in favorable benefit/risk ratio compared with standard care. The meta-analysis of randomized controlled trials was updated to put findings in the context of all available evidence. Methods TESPI was a multicenter, open-label with blinded outcome evaluation, randomized, controlled trial. Main clinical endpoints were 90-day favorable functional outcome (mRS score 0–2) and mortality and symptomatic intracerebral hemorrhage. The trial was prematurely terminated for ethical reasons after publication of IST-3 trial which provided evidence of treatment benefit in elderly. Results Of the planned 600 patients, 191 (88 assigned to alteplase) were enrolled. Overall, 24/83 (28.9%) alteplase patients had a favorable outcome compared to 22/95 (23.2%) controls (non-significant absolute difference of 5.7% for alteplase; OR 1.35, 95% CI 0.69–2.64, P = 0.381). Rates of death were non-significantly lower in the alteplase patients (18.1% vs. 26.5%); rates of symptomatic intracerebral hemorrhage were similar between the two groups (5.9% vs. 5.1%). The updated meta-analysis showed consistent results with prior estimates and add weights. Conclusions The effects of alteplase observed in this interrupted trial did not reach statistical significance, probably for the small numbers, but are consistent with and add weight to the sum total of the randomized evidence demonstrating that alteplase is beneficial in patients with acute ischemic stroke aged over 80 years, particularly if given within 3 h.

Supplemental material, WSO884525 Supplemetal Material for Thrombolysis in elderly stroke patients in Italy (TESPI) trial and updated meta-analysis of randomized controlled trials by Svetlana Lorenzano, Annarita Vestri, Paolo Bovi, Manuel Cappellari, Paolo Stanzione, Domenico Samà, Maddalena Bruscoli, Milena Cavazzuti, Andrea Zini, Maurizia Rasura, Mario Beccia, Giancarlo Comi, Maria Sessa, Carlo Gandolfo, Maurizio Balestrino, Giancarlo Agnelli, Valeria Caso, Piercarlo Gerbino Promis, Claudio Pozzessere, Sabrina Anticoli, Francesco Perini, Michela Marcon, Annalisa Vinattieri, Alba Caruso, Mauro Magoni, Mauro Furlan, Giovanni Orlandi, Vincenzo Di Lazzaro, Mariarosaria Valente, Patrizia Nencini and Danilo Toni on behalf of the TESPI trial Investigators in International Journal of Stroke

The possibility to locally incorporate/remove hydrogen atoms in/from dilute-nitride semiconductors is demonstrated. This method can be applied to the fabrication of site-controlled single-photon emitters but also to the optimization/fabrication of photonic devices, via refractive-index engineering. ? OSA 2019 ? 2019 The Author(s)

By means of time-resolved photoluminescence (TR-PL) spectroscopy, we present a detailed investigation of the carrier relaxation dynamics in a CsPbBr3 bulk sample and microcrystal ensemble at cryogenic temperature on a picosecond time scale. We provide evidence of a long temperature-dependent cooling rate for the excitons and free carriers population, with an initial cooling time constant of a few tens of picoseconds. A relaxation bottleneck in the thermalization process was found that cannot be explained by the Auger effect or hot phonon population, since we address a very low excitation regime, not commonly investigated in literature, where such processes are not effective. Adding a continuous wave optical bias to the picosecond excitation, we probed the photoinduced PL decrease of the localized states and the photoinduced PL increase of the population in the high energy states. A long recovery time from the photoinduced PL decrease was found for localized states and quite significant differences were detected, depending on the resonance/off resonance bias used in the experiment.

Semiconductor quantum dots (QDs), made of III-V semiconductors alloys, have attracted increasing interest in the last two decades, especially for their possible usage in quantum information technology. However, for such advanced applications, the requisite control of the QD's position cannot be achieved by the conventional growth techniques. Moreover, silicon (Si) dominates the microelectronic technology but its use is limited for optoelectronic applications due to its indirect bandgap. Therefore, the possibility to integrate QDs made of III-V alloys on a Si-based platform and circuitry is of the utmost importance. However, this is hindered by the very different lattice constants and thermal expansion coefficients of Si and GaAs, which generate strain and defects. In this paper we overcome the mismatch problems using the self-limited growth of germanium on micro-patterned (001) Si to obtain a relaxed GaAs(111) oriented epilayer for the subsequent heteroepitaxy of III-V nanostructures. In particular we optically characterize a stack of three GaAs/AlGaAs quantum wells (QWs) grown on top of the Si/Ge pillars. We provide clear evidence of the presence of naturally formed QDs, due to QW thickness fluctuations, and their position control with micrometer resolution, given by the pillar distance.

The integration of optoelectronic and photonic devices based on III–V semiconductors on Si-based integrated circuits is far from being optimized despite its technological relevance. Due to the differences in lattice parameters and thermal expansion coefficients, high density of defect is introduced. We propose a novel approach for the fabrication of GaAs/AlGaAs heterostructures on nominal (001) Si substrates based on suspended Ge epilayers. To eliminate dislocations and thermal cracks we use a patterned Si substrate on which we grow with a LEPECVD system, separated vertical Ge micro-crystals, efficient in eliminating the threading dislocations and the thermal strain. From such micro-crystals, a suspended Ge layer, hundreds of microns wide and free of thermal stress can be obtained. The suspended Ge shows a wavy surface on which double steps are formed, permitting the reduction of anti-phase domains even in absence of substrate tilt. GaAs layers were grown on such Ge/Si substrate in a MBE system. Different growth recipes were studied. We found that diffusion length of Ga adatom, which is related to the average nucleation distance of GaAs islands, has a crucial role in the determination of the average APD size. In the optimum growth conditions, it was possible to observe average dimensions of APD free area with a lateral dimension of 30 μm. Macro and Micro-PL of AlGaAs/GaAs QWs grew on top show that uniform, optical quality GaAs layers are fabricated.

We report on the growth and optical characterization by macro and micro photoluminescence measurements of high optical quality GaAs quantum nanostructures grown by droplet epitaxy on Ge and Si substrates. The quantum nanostructures show optical performances comparable to those achievable with the most advanced realized on GaAs substrates. The adopted growth procedures show also the possibility to fabricate the active layer maintaining a low thermal budget compatible with back-end integration of the fabricated materials on integrated circuits. We demonstrate the possibility to embed GaAs nanostructured devices such as intersubband detectors and single quantum emitters on Si substrates. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Many of the most advanced applications of semiconductor quantum dots (QDs) in quantum information technology require a fine control of the QDs' position and confinement potential, which cannot be achieved with conventional growth techniques. Here, a novel and versatile approach for the fabrication of site-controlled QDs is presented. Hydrogen incorporation in GaAsN results in the formation of N-2H and N-2H-H complexes, which neutralize all the effects of N on GaAs, including the N-induced large reduction of the bandgap energy. Starting from a fully hydrogenated GaAs/GaAsN:H/GaAs quantum well, the NH bonds located within the light spot generated by a scanning near-field optical microscope tip are broken, thus obtaining site-controlled GaAsN QDs surrounded by a barrier of GaAsN:H (laterally) and GaAs (above and below). By adjusting the laser power density and exposure time, the optical properties of the QDs can be finely controlled and optimized, tuning the quantum confinement energy over more than 100 meV and resulting in the observation of single-photon emission from both the exciton and biexciton recombinations. This novel fabrication technique reaches a position accuracy

We present a high spatial resolution photoluminescence (PL) study of CsPbBr3 microcrystals by means of near-field optical microscopy and micro-PL. Correlation between the PL emission features and the crystal size are presented and discussed.

Importance Predictors of lethal arrhythmic events (LAEs) after a pediatric diagnosis of hypertrophic cardiomyopathy (HCM) are unresolved. Existing algorithms for risk stratification are limited to patients older than 16 years because of a lack of data on younger individuals. Objective To describe the long-term outcome of pediatric-onset HCM and identify age-specific arrhythmic risk factors. Design, Setting, and Participants This study assessed patients with pediatric-onset hypertrophic cardiomyopathy diagnosed from 1974 to 2016 in 2 national referral centers for cardiomyopathies in Florence, Italy. Patients with metabolic and syndromic disease were excluded. Exposures Patients were assessed at 1-year intervals, or more often, if their clinical condition required. Main Outcomes and Measures Lethal arrhythmic events (LAEs) and death related to heart failure. Results Of 1644 patients with HCM, 100 (6.1%) were 1 to 16 years old at diagnosis (median [interquartile range], 12.2 [7.3-14.1] years). Of these, 63 (63.0%) were boys. Forty-two of the 100 patients (42.0%) were symptomatic (defined as an New York Heart Association classification higher than 1 or a Ross score greater than 2). The yield of sarcomere gene testing was 55 of 70 patients (79%). During a median of 9.2 years during which a mean of 1229 patients were treated per year, 24 of 100 patients (24.0%) experienced cardiac events (1.9% per year), including 19 LAEs and 5 heart failure–related events (3 deaths and 2 heart transplants). Lethal arrhythmic events occurred at a mean (SD) age of 23.1 (11.5) years. Two survivors of LAEs with symptoms of heart failure experienced recurrent cardiac arrest despite an implantable cardioverter defibrillator. Risk of LAE was associated with symptoms at onset (hazard ratio [HR], 8.2; 95% CI, 1.5-68.4; P = .02) and Troponin I or Troponin T gene mutations (HR, 4.1; 95% CI, 0.9-36.5; P = .06). Adult HCM risk predictors performed poorly in this population. Data analysis occurred from December 2016 to October 2017. Conclusions and Relevance Pediatric-onset HCM is rare and associated with adverse outcomes driven mainly by arrhythmic events. Risk extends well beyond adolescence, which calls for unchanged clinical surveillance into adulthood. In this study, predictors of adverse outcomes differ from those of adult populations with HCM. In secondary prevention, the implantable cardioverter defibrillator did not confer absolute protection in the presence of limiting symptoms of heart failure.

Inorganic CsPbBr3 perovskite devices have been manufactured and tested as dosimeters under both conventional and Intensity Modulated Radiotherapy (IMRT) X-ray beams. Samples showed a very good linear dependence of the collected charge/current on dose/dose rates in the range of 0.1–5.0 Gy/0.1–4.0 Gy/min of interest for clinical applications. A device sensitivity of about 70 nC/Gy mm3 compares favorably with other solid-state dosimeters. The first verification of an IMRT dose profile of a prostate cancer treatment, performed by moving the perovskite device on a 10 cm-long profile with a 0.5 mm pitch, showed agreement within 5% with the dose distribution required by the treatment planning system.

We present time-resolved photoluminescence measurements of $\mathrm{In}\mathrm{As}∕\mathrm{Ga}\mathrm{As}$ quantum dots showing a relevant interplay between recombination kinetics and thermalization processes. By time-resolved and steady-state measurements we experimentally demonstrate that the thermal population of optically inactive states fully accounts for the increase of the intrinsic radiative lifetime in quantum dots when the lattice temperature raises. Experimental data are compared with model predictions for the electronic structure of the quantum dot, and the dark optical transitions involved in the thermalization nicely correspond to the first-hole-excited levels. In addition, the observation of thermalization between the electronic levels allows us to estimate the relaxation time to the ground state, which turns out to be in the ps time scale.