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Quantum fluids of light are realized in semiconductor microcavities using exciton-polaritons, solid-state quasi-particles with a light mass and sizeable interactions. Here, we use the microscopic analogue of oceanographic techniques to measure the excitation spectrum of a thermalised polariton condensate. Increasing the fluid density, we demonstrate the transition from a free-particle parabolic dispersion to a linear, sound-like Goldstone mode characteristic of superfluids at equilibrium. Notably, we reveal the effect of an asymmetric pumping by showing that collective excitations are created with a definite direction with respect to the condensate. Furthermore, we measure the critical sound speed for polariton superfluids close to equilibrium. Polariton condensates undergo continuous driving and dissipation, posing challenges for investigating their collective behaviour. Ballarini et al. adapt an oceanographic technique to measure the asymmetric occupation of the Goldstone mode and identify similarities with equilibrium condensates.

The Berezinskii-Kosterlitz-Thouless phase transition from a disordered to a quasi-ordered state, mediated by the proliferation of topological defects in two dimensions, governs seemingly remote physical systems ranging from liquid helium, ultracold atoms and superconducting thin films to ensembles of spins. Here we observe such a transition in a short-lived gas of exciton-polaritons, bosonic light-matter particles in semiconductor microcavities. The observed quasi-ordered phase, characteristic for an equilibrium two-dimensional bosonic gas, with a decay of coherence in both spatial and temporal domains with the same algebraic exponent, is reproduced with numerical solutions of stochastic dynamics, proving that the mechanism of pairing of the topological defects (vortices) is responsible for the transition to the algebraic order. This is made possible thanks to long polariton lifetimes in high-quality samples and in a reservoir-free region. Our results show that the joint measurement of coherence both in space and time is required to characterize driven-dissipative phase transitions and enable the investigation of topological ordering in open systems.

Fluorescent penetrant inspection (FPI) is a well-assessed non-destructive test method used in manufacturing for detecting cracks and other flaws of the product under test. This is a critical phase in the mechanical and aerospace industrial sector. The purpose of this work was to present the implementation of an automated inspection system, developing a vision-based expert system to automate the inspection phase of the FPI process in an aerospace manufacturing line. The aim of this process was to identify the defectiveness status of some mechanical parts by the means of images. This paper will present, test and compare different machine learning architectures to perform the automated defect detection on a given dataset. For each test sample, several images at different angles were captured to properly populate the input dataset. In this way, the defectiveness status should be found combining the information contained in all the pictures. In particular, the system was designed for increasing the reliability of the evaluations performed on the airplane part, by implementing proper artificial intelligence (AI) techniques to reduce current human operators’ effort. The results show that, for applications in which the dataset available is quite small, a well-designed feature extraction process before the machine learning classifier is a very important step for achieving high classification accuracy.

Quantum fluids of light are an emerging platform for energy-efficient signal processing, ultrasensitive interferometry and quantum simulators at elevated temperatures. Here we demonstrate all-optical control of the topological excitations in a large polariton condensate realizing the bosonic analogue of a long Josephson junction and inducing the nucleation of Josephson vortices. When a phase difference is imposed at the boundaries of the condensate, two extended regions become separated by a sharp phase jump of π radians and a solitonic depletion of the density, forming an insulating barrier with a suppressed order parameter. The superfluid behaviour—characterized by a smooth phase gradient across the system instead of the sharp phase jump—is recovered at higher polariton densities and is mediated by the nucleation of Josephson vortices within the barrier. Our results contribute to the understanding of dissipation and stability of elementary excitations in macroscale quantum systems.All-optical control of the topological excitations of a superfluid of light is demonstrated in a high-quality-factor semiconductor microcavity. Recovery of superfluid behaviour at high polariton densities and bosonic Josephson vortices are observed.

The optimization of investment portfolios represents a pivotal task within the field of financial economics. Its objective is to identify asset combinations that meet specified criteria for return and risk. Traditionally, the maximization of the Sharpe Ratio, often achieved through quadratic programming, has constituted a popular approach for this purpose. However, real-world scenarios frequently necessitate more complex considerations, particularly in relation to portfolio diversification with a view to mitigating sector-specific risks and enhancing stability. The incorporation of diversification alongside the Sharpe Ratio into the optimization model creates a joint optimization task, which can be formulated as Quadratic Unconstrained Binary Optimization (QUBO) and addressed using quantum annealing or hybrid computing techniques. These techniques offer promising solutions. We present a novel QUBO formulation for this optimization, detailing its mathematical formulation and demonstrating its advantages over classical methods, particularly in handling diversification objectives. By leveraging available QUBO solvers and hybrid approaches, we explore the feasibility of handling large-scale problems while highlighting the importance of diversification in achieving robust portfolio performance. We finally elaborate on the results showing the trade-off between the observed values of the portfolio’s Sharpe Ratio and diversification, as a natural consequence of solving a multi-objective optimization problem.

We report the clinical and EEG data of two patients harboring heterozygous SLC6A1 mutations, who presented with typical absence seizures at 3 Hz spike and wave as well as with mild cognitive disability. Neuroradiological and other laboratory investigations were normal. Our observations suggest that SLC6A1 mutations can be suspected in children with typical absences as the only seizure type, especially if associated with, even mild, cognitive deficits.

Polanski and Perception focuses on Roman Polanski's interest in the nature of perception and how this is manifested in his films. Informed by the work of neuropsychologist R. L. Gregory, this volume primarily focuses on two sets of films: the Apartment trilogy and the Investigation trilogy. This book also includes case studies of other films.

Objectives We describe the Residras registry, dedicated to Dravet syndrome (DS) and to other phenotypes related to SCN1A mutations, as a paradigm of registry for rare and complex epilepsies. Our primary objectives are to present the tools and framework of the integrative platform, the main characteristics emerging from the patient cohort included in the registry, with emphasis on demographic, clinical outcome, and mortality. Methods Standardized data of enrolled pediatric and adult patients were collected in 24 Italian expert centers and regularly updated at least on a yearly basis. Patients were prospectively enrolled, at registry starting, but historical retrospective data were also included. Results At present, 281 individuals with DS and a confirmed SCN1A mutation are included. Most patients have data available on epilepsy (n = 263) and their overall neurological condition (n = 255), based on at least one follow‐up update. Median age at first clinical assessment was 2 years (IQR 0–9) while at last follow‐up was 11 years (IQR 5–18.5). During the 7‐year activity of the registry, five patients died resulting in a mortality rate of 1.84 per 1000‐person‐years. When analyzing clinical changes over the first 5‐year follow‐up, we observed a significant difference in cognitive function (P < 0.001), an increased prevalence of behavioral disorders including attention deficit (P < 0.001), a significant worsening of language (P = 0.001), and intellectual disability (P < 0.001). Significance The Residras registry represents a large collection of standardized national data for the DS population. The registry platform relies on a shareable and interoperable framework, which promotes multicenter high‐quality data collection. In the future, such integrated platform may represent an invaluable asset for easing access to cohorts of patients that may benefit from clinical trials with emerging novel therapies, for drug safety monitoring, and for delineating natural history. Its framework makes it improvable based on growing experience with its use and easily adaptable to other rare and complex epilepsy syndromes.

Febrile infection-related epilepsy syndrome (FIRES) is a rare catastrophic epileptic encephalopathy with a yet undefined etiology, affecting healthy children. It is characterized by acute manifestation of recurrent seizures or refractory status epilepticus preceded by febrile illness, but without evidence of infectious encephalitis. To date, the absence of specific biomarkers poses a significant diagnostic challenge; nonetheless, early diagnosis is very important for optimal management. FIRES is mostly irreversible and its sequelae include drug-resistant epilepsy and neuropsychological impairments. The treatment of FIRES represents a significant challenge for clinicians and is associated with low success rates. Early introduction of ketogenic diet seems to represent the most effective and promising treatment. This review aims to highlight the most recent insights on clinical features, terminology, epidemiology, pathogenesis, diagnostic challenges and therapeutic options.