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Physical unclonable functions (PUFs) are complex physical objects that aim at overcoming the vulnerabilities of traditional cryptographic keys, promising a robust class of security primitives for different applications. Optical PUFs present advantages over traditional electronic realizations, namely, a stronger unclonability, but suffer from problems of reliability and weak unpredictability of the key. We here develop a two-step PUF generation strategy based on deep learning, which associates reliable keys verified against the National Institute of Standards and Technology (NIST) certification standards of true random generators for cryptography. The idea explored in this work is to decouple the design of the PUFs from the key generation and train a neural architecture to learn the mapping algorithm between the key and the PUF. We report experimental results with all-optical PUFs realized in silica aerogels and analyzed a population of 100 generated keys, each of 10,000 bit length. The key generated passed all tests required by the NIST standard, with proportion outcomes well beyond the NIST’s recommended threshold. The two-step key generation strategy studied in this work can be generalized to any PUF based on either optical or electronic implementations. It can help the design of robust PUFs for both secure authentications and encrypted communications.

Background Nutrition is an environmental factor affecting bone health. Nutrition is considered essential to achieve and maintain optimal bone mass. Mediterranean diet (MD) has shown to prevent bone disease. Aim of this study is to investigate the relationship between bone health status and adherence the MD. Methods Four-hundred eighteen healthy people (105 males and 313 females, age 50 ± 14 years) were recruited in the outdoor hospital of the “Campus Salute Onlus” held in Piazza del Plebiscito in Naples, October 17–20th 2013 and 09–11th October 2014. All subjects underwent clinical assessment, calcaneal quantitative ultrasound (QUS) scanner and PREvención con DIeta MEDiterránea (PREDIMED) questionnaire. Results Globally, prevalence of osteoporosis and osteopenia were 7.7 and 46.0%, respectively. The majority of subjects (60.5%) had an average score (score 6–9) of adherence to MD. The T-score showed positive correlation with PREDIMED score (r = 0.250, p  < 0.001). The higher T-scores were positively associated with a higher consumption of extra-virgin olive oil (EVOO), vegetables, fruits, legumes, and fish and negatively associated with consumption of red meat. The higher T-scores were positively associated with the highest odds of PREDIMED scores (higher adherence) (OR 6.91, IC 6.27–7.61, p  < 0.001). Multiple regression analysis models indicated that, among the single food items investigated, high T-score can be predicted by consumption of EVOO ( p  < 0.001), fish ( p  < 0.001) and fruit ( p  = 0.002) intake. A PREDIMED score of 3 was found to be predictive for a low T-score (α = 0.05, R-squared index = 0.417). Conclusions The results demonstrate a positive correlation between bone health status and adherence to MD, suggesting that a high adherence to MD promotes bone health. The observations here reported confirmed that a specific dietary approach, such as MD, can represent a modifiable environmental factor for osteoporosis’ prevention.

Molecular dyes, plasmonic nanoparticles and colloidal quantum dots are widely used in biomedical optics. Their operation is usually governed by spontaneous processes, which results in broad spectral features and limited signal-to-noise ratio, thus restricting opportunities for spectral multiplexing and sensing. Lasers provide the ultimate spectral definition and background suppression, and their integration with cells has recently been demonstrated. However, laser size and threshold remain problematic. Here, we report on the design, high-throughput fabrication and intracellular integration of semiconductor nanodisk lasers. By exploiting the large optical gain and high refractive index of GaInP/AlGaInP quantum wells, we obtain lasers with volumes 1000-fold smaller than the eukaryotic nucleus ( V laser  < 0.1 µm 3 ), lasing thresholds 500-fold below the pulse energies typically used in two-photon microscopy ( E th  ≈ 0.13 pJ), and excellent spectral stability (<50 pm wavelength shift). Multiplexed labeling with these lasers allows cell-tracking through micro-pores, thus providing a powerful tool to study cell migration and cancer invasion. While the sharp emission lines of microlasers are advantageous for cell tagging, their relatively large size can impede cell migration and behavior. Here, Fikouras et al. develop nano-sized lasers that can readily tag and track various types of cells, including through narrow constrictions.

COVID-19 pandemic resulted in about 165 million infections and 3.4 million deaths all over the world across 15 months. The most severe clinical presentation of COVID-19 diseases is interstitial pneumonia. In this paper we describe clinical outcomes based on radiological features as well as the pattern of haematochemical parameters and IgG/IgM antibodies in 75 patients hospitalized due to COVID-related interstitial pneumonia not requiring intensive care assistance. Each patient underwent routine laboratory tests, including inflammatory markers and coagulation profile at baseline. Computed Tomography (CT) was performed at baseline and after 3 months to assess the persistence of radiological sequelae. A Generalized Linear Model (GLM) was used to test for each patient the association between individual haematochemical parameters at the time of hospital admission and the subsequent radiological features after three months. The presence of IgG antibodies was quantitatively determined in 70 patients at the time of hospital admission and after 3 months. A subgroup of 49 and 21 patients underwent additional dosage of IgG after 6 and 12 months, respectively. IgM serological antibodies were available for 17 patients at baseline and 61 at T3, with additional follow-up for 51 and 20 subjects after 6 and 12 months, respectively. Only 28 out of 75 patients discharged from the hospital were totally healed after 3 months, while 47 patients (62.7%) still presented radiological sequelae. According to the GLM model, specific haematochemical baseline parameters-such as IL-6, GPT, platelets and eosinophil count-showed a statistically significant association with the presence of radiological sequelae at month 3 highlighting an OR = 0.5, thus meaning that subjects completely healed after 3 months presented half levels of IL-6 at baseline compared to patients with sequelae. In general, IgG serum levels were always higher than IgM at the time of hospitalization (75% at T0; n = 12 out of 16 patients with data available in both visits), after 3 months (72.1%; n = 44 out of 61 pts.), after 6 months (56.8%; 25 out of 44 pts.), and one year after hospitalization (60%; 12 out of 20 pts.). Overall, IgG and IgM serum levels presented a statistically significant decreasing trend from the baseline to month 3, 6 and 12. One patient presented an increase in IgM between baseline and month 3 but negative PCR test for SARS-COV2 on throat swab. As supported by our findings on 75 patients, COVID-related interstitial pneumonia triggers early IgG levels (higher than IgM) that gradually decrease over 12 months. Mid-term sequelae are still detectable at lung Computed Tomography after 3 months from the hospital admission. Occasionally, it is possible to observe increase of IgM levels in presence of low concentrations of IgG and negative PCR ELISA tests for SARS-COV2 RNA. Baseline levels of IL-6 could be proposed as predictor of radiological mid/long-term sequelae after COVID-related interstitial pneumonia.

Metasurface holograms are typically fabricated on rigid substrates. Here we experimentally demonstrate broadband, flexible, conformable, helicity multiplexed metasurface holograms operating in the visible range, offering increased potential for real life out-of-the-lab applications. Two symmetrically distributed holographic images are obtained when circularly polarized light impinges on the reflective-type metasurface positioned on non-planar targets. The two off-axis images with high fidelity are interchangeable by controlling the helicity of incident light. Our metasurface features the arrangement of spatially varying gold nanorods on a flexible, conformable epoxy resist membrane to realize a Pancharatnam-Berry phase profile. These results pave the way to practical applications including polarization manipulation, beam steering, novel lenses, and holographic displays.

Organic light-emitting diodes (OLEDs) are thin film optoelectronic devices that feature simple fabrication, light weight and broad tunability, which makes them widely used in mobile phone and TV displays. As a flat and surface-emitting light source, OLEDs are also used in emerging applications such as optical wireless communications, biophotonics and sensing, where the ability to integrate with other technologies makes them good candidates to realise miniaturised photonic platforms. Control of the OLED far-field emission is increasingly important for both displays and these emerging applications. At present, however, studies mainly focus on tuning the electroluminescence (EL) spectrum and emission directionality. Fine-tuning of the far-field emission is particularly challenging and is limited by the low spatial coherence of OLEDs. In this work, we show that it is possible for a single OLED to project a high-resolution image when combined with a holographic metasurface as a compact projection system. The metasurface-OLED projector allows us to directly manipulate the OLED far-field emission and display holographic images on a screen. Here, we further show how the projected image quality relates to the spatial coherence length and the spectrum of the OLED. We believe our demonstration provides a path towards a miniaturised and highly integrated metasurface display.

Ultrafast pulse characterisation is crucial for studying processes that occur at femtosecond timescales and below. Because of this, various methods have been developed to recover a pulse’s electric field profile at these durations, with the frequency-resolved optical gating (FROG) technique being the most common. However, this approach is computationally expensive and suffers from limitations in terms of robustness and reliability. In this regard, recent publications have demonstrated that applying machine learning towards ultrafast pulse recovery can alleviate these issues, providing more accurate retrievals. Inspired by these works, we propose an encoder–decoder scheme for a FROG system which exploits dual harmonic generation in low-index thin films. Specifically, we demonstrate enhanced reliability and accuracy of ultrafast pulse recovery when compared to machine learning approaches using second or third harmonic signals independently. As the amount of information used to train each neural network is kept constant, this study demonstrates and benchmarks the technological advantages of contextual information analysis involving multiple nonlinear processes.

In this work, we demonstrate nonflat metasurface holograms with applications in imaging, sensing, and anticounterfeiting. For these holograms, the image and its symmetry properties, with respect to the polarization of the light, depend on the specific shape of the substrate. Additionally, the sensitivity of the holographic image to the substrate shape can be engineered by distributing the phase information into determined areas of the metasurface.

Background and Objectives: Non-melanoma skin cancers (NMSCs) include basal cell carcinoma (BCC) and squamous-cell carcinoma (SCC), as well as a wide range of rare skin tumors. NMSCs is the most frequently diagnosed type of tumor among Caucasians. We aimed at estimating the incidence and mortality of NMSCs in the Salento area (Lecce province, Southern Italy), whose population is assumed to experience heavy and frequent sun exposure due to climatic/environmental factors, both for working and leisure activities. Materials and Methods: We computed the incidence of NMSCs in the Province of Lecce by examining the comprehensive real-world data collected by the local cancer registry, which covers all the 830,000 inhabitants, over a period of fifteen years (from 2003 to 2017), with a focus on the latest 5 years (2013–2017) for the analysis of the different histologic morphologies of these tumors. The incidence of NMSCs has been described in terms of absolute frequencies, crude rates and age-adjusted direct standardized rates (DSR). Joinpoint analysis was used to examine temporal trends in the incidence of NMSCs and estimate annual percent changes (APCs). Results: During the period of 2003–2017, the incidence of NMSCs reached a direct standardized rate (DSR) of 162.62 per 100,000 in men (mortality 1.57 per 100,000) and 89.36 per 100,000 in women (mortality 0.52 per 100,000), respectively. The incidence significantly increased among both men and women across the entire period. Basal cell carcinoma (BCC), with its different morphologies, represented about 67.6% of the NMSCs in men (n = 2139 out of a total of 3161 tumors observed between 2013 and 2017) and about 75.8% of the NMSCs in women (n = 1718 out of a total of 2264 tumors from 2013 to 2017), thus accounting for the vast majority of NMSCs. The results are consistent with the literature data carried out both at national and international level. Conclusions: Proper monitoring of this phenomenon through timely reporting and recording of all new NMSC cases is necessary to develop new preventive strategies.

Titanium nitride (TiN) is a refractory metal nitride compound with the potential to function as an alternative plasmonic material to gold, especially for high-power linear and nonlinear applications such as materials processing, telecommunications, and laser systems. This paper presents a simple, electron beam evaporation based deposition process to fabricate sub-100 nm TiN thin films at low temperatures. The dependence of optical properties and film thickness on deposition temperature was explored and it was observed that low-temperature annealing during deposition further enhances the plasmonic properties of the films. These results are essential for promoting the utilisation of highly metallic TiN thin films in plasmonic and photonic applications.