Artificial Intelligence in Classical and Quantum Photonics

The last decades saw a huge rise of artificial intelligence (AI) as a powerful tool to boost industrial and scientific research in a broad range of fields. AI and photonics are developing a promising two-way synergy: on the one hand, AI approaches can be used to control a number of complex linear and nonlinear photonic processes, both in the classical and quantum regimes; on the other hand, photonics can pave the way for a new class of platforms to accelerate AI-tasks. This review provides the reader with the fundamental notions of machine learning (ML) and neural networks (NNs) and presents the main AI applications in the fields of spectroscopy and chemometrics, computational imaging (CI), wavefront shaping and quantum optics. The review concludes with an overview of future developments of the promising synergy between AI and photonics

Effects of thoraco-pelvic supports during prone position in patients with acute lung injury/acute respiratory distress syndrome: a physiological study

INTRODUCTION: This study sought to assess whether the use of thoraco-pelvic supports during prone positioning in patients with acute lung injury/acute respiratory distress syndrome (ALI/ARDS) improves, deteriorates or leaves unmodified gas exchange, hemodynamics and respiratory mechanics. METHODS: We studied 11 patients with ALI/ARDS, sedated and paralyzed, mechanically ventilated in volume control ventilation. Prone positioning with or without thoraco-pelvic supports was applied in a random sequence and maintained for a 1-hour period without changing the ventilation setting. In four healthy subjects the pressures between the body and the contact surface were measured with and without thoraco-pelvic supports. Oxygenation variables (arterial and central venous), physiologic dead space, end-expiratory lung volume (helium dilution technique) and respiratory mechanics (partitioned between lung and chest wall) were measured after 60 minutes in each condition. RESULTS: With thoraco-pelvic supports, the contact pressures almost doubled in comparison with those measured without supports (19.1 ± 15.2 versus 10.8 ± 7.0 cmH(2)O, p ≤ 0.05; means ± SD). The oxygenation-related variables were not different in the prone position, with or without thoraco-pelvic supports; neither were the CO(2)-related variables. The lung volumes were similar in the prone position with and without thoraco-pelvic supports. The use of thoraco-pelvic supports, however, did lead to a significant decrease in chest wall compliance from 158.1 ± 77.8 to 102.5 ± 38.0 ml/cmH(2)O and a significantly increased pleural pressure from 4.3 ± 1.9 to 6.1 ± 1.8 cmH(2)O, in comparison with the prone position without supports. Moreover, when thoraco-pelvic supports were added, heart rate increased significantly from 82.1 ± 17.9 to 86.7 ± 16.7 beats/minute and stroke volume index decreased significantly from 37.8 ± 6.8 to 34.9 ± 5.4 ml/m(2). The increase in pleural pressure change was associated with a significant increase in heart rate (p = 0.0003) and decrease in stroke volume index (p = 0.0241). CONCLUSION: The application of thoraco-pelvic supports decreases chest wall compliance, increases pleural pressure and slightly deteriorates hemodynamics without any advantage in gas exchange. Consequently, we stopped their use in clinical practice

Comparing Transmission- and Epi-BCARS: A Transnational Round Robin on Solid State Materials

Broadband coherent anti-Stokes Raman scattering (BCARS) is an advanced Raman spectroscopy method that combines the spectral sensitivity of spontaneous Raman scattering (SR) with the increased signal intensity of single-frequency coherent Raman techniques. These two features make BCARS particularly suitable for ultra-fast imaging of heterogeneous samples, as already shown in biomedicine. Recent studies demonstrated that BCARS also shows exceptional spectroscopic capabilities when inspecting crystalline materials like lithium niobate and lithium tantalate, and can be used for fast imaging of ferroelectric domain walls. These results strongly suggest the extension of BCARS towards new imaging applications like mapping defects, strain, or dopant levels, similar to standard SR imaging. Despite these advantages, BCARS suffers from a spurious and chemically unspecific non-resonant background (NRB) that distorts and shifts the Raman peaks. Post-processing numerical algorithms are then used to remove the NRB and to obtain spectra comparable to SR results. Here, we show the reproducibility of BCARS by conducting an internal Round Robin with two different BCARS experimental setups, comparing the results on different crystalline materials of increasing structural complexity: diamond, 6H-SiC, KDP, and KTP. First, we compare the detected and phase-retrieved signals, the setup-specific NRB-removal steps, and the mode assignment. Subsequently, we demonstrate the versatility of BCARS by showcasing how the selection of pump wavelength, pulse width, and detection geometry can be tailored to suit the specific objectives of the experiment. Finally, we compare and optimize measurement parameters for the high-speed, hyperspectral imaging of ferroelectric domain walls in lithium niobate.Comment: 12 pages, 8 figure

Effect of a heated humidifier during continuous positive airway pressure delivered by a helmet

INTRODUCTION: The helmet may be an effective interface for the delivery of noninvasive positive pressure ventilation. The high internal gas volume of the helmet can act as a 'mixing chamber', in which the humidity of the patient's expired alveolar gases increases the humidity of the dry medical gases, thus avoiding the need for active humidification. We evaluated the temperature and humidity of respiratory gases inside the helmet, with and without a heated humidifier, during continuous positive airway pressure (CPAP) delivered with a helmet. METHODS: Nine patients with acute respiratory failure (arterial oxygen tension/fractional inspired oxygen ratio 209 +/- 52 mmHg) and 10 healthy individuals were subjected to CPAP. The CPAP was delivered either through a mechanical ventilator or by continuous low (40 l/min) or high flow (80 l/min). Humidity was measured inside the helmet using a capacitive hygrometer. The level of patient comfort was evaluated using a continuous scale. RESULTS: In patients with acute respiratory failure, the heated humidifier significantly increased the absolute humidity from 18.4 +/- 5.5 mgH2O/l to 34.1 +/- 2.8 mgH2O/l during ventilator CPAP, from 11.4 +/- 4.8 mgH2O/l to 33.9 +/- 1.9 mgH2O/l during continuous low-flow CPAP, and from 6.4 +/- 1.8 mgH2O/l to 24.2 +/- 5.4 mgH2O/l during continuous high-flow CPAP. Without the heated humidifier, the absolute humidity was significantly higher with ventilator CPAP than with continuous low-flow and high-flow CPAP. The level of comfort was similar for all the three modes of ventilation and with or without the heated humidifier. The findings in healthy individuals were similar to those in the patients with acute respiratory failure. CONCLUSION: The fresh gas flowing through the helmet with continuous flow CPAP systems limited the possibility to increase the humidity. We suggest that a heated humidifier should be employed with continuous flow CPAP systems

The effect of different volumes and temperatures of saline on the bladder pressure measurement in critically ill patients

INTRODUCTION: Intra-abdominal hypertension is common in critically ill patients and is associated with increased severity of organ failure and mortality. The techniques most commonly used to estimate intra-abdominal pressure are measurements of bladder and gastric pressures. The bladder technique requires that the bladder be infused with a certain amount of saline, to ensure that there is a conductive fluid column between the bladder and the transducer. The aim of this study was to evaluate the effect of different volumes and temperatures of infused saline on bladder pressure measurements in comparison with gastric pressure. METHODS: Thirteen mechanically ventilated critically ill patients (11 male; body mass index 25.5 +/- 4.6 kg/m2; arterial oxygen tension/fractional inspired oxygen ratio 225 +/- 48 mmHg) were enrolled. Bladder pressure was measured using volumes of saline from 50 to 200 ml at body temperature (35 to 37 degrees C) and room temperature (18 to 20 degrees C). RESULTS: Bladder pressure was no different between 50 ml and 100 ml saline (9.5 +/- 3.7 mmHg and 13.7 +/- 5.6 mmHg), but it significantly increased with 150 and 200 ml (21.1 +/- 10.4 mmHg and 27.1 +/- 15.5 mmHg). Infusion of saline at room temperature caused a significantly greater bladder pressure compared with saline at body temperature. The lowest difference between bladder and gastric pressure was obtained with a volume of 50 ml. CONCLUSION: The bladder acts as a passive structure, transmitting intra-abdominal pressure only with saline volumes between 50 ml and 100 ml. Infusion of a saline at room temperature caused a higher bladder pressure, probably because of contraction of the detrusor bladder muscl

Deep ensemble learning and transfer learning methods for classification of senescent cells from nonlinear optical microscopy images

The success of chemotherapy and radiotherapy anti-cancer treatments can result in tumor suppression or senescence induction. Senescence was previously considered a favorable therapeutic outcome, until recent advancements in oncology research evidenced senescence as one of the culprits of cancer recurrence. Its detection requires multiple assays, and nonlinear optical (NLO) microscopy provides a solution for fast, non-invasive, and label-free detection of therapy-induced senescent cells. Here, we develop several deep learning architectures to perform binary classification between senescent and proliferating human cancer cells using NLO microscopy images and we compare their performances. As a result of our work, we demonstrate that the most performing approach is the one based on an ensemble classifier, that uses seven different pre-trained classification networks, taken from literature, with the addition of fully connected layers on top of their architectures. This approach achieves a classification accuracy of over 90%, showing the possibility of building an automatic, unbiased senescent cells image classifier starting from multimodal NLO microscopy data. Our results open the way to a deeper investigation of senescence classification via deep learning techniques with a potential application in clinical diagnosis

Fingerprint multiplex CARS at high speed based on supercontinuum generation in bulk media and deep learning spectral denoising

We introduce a broadband coherent anti-Stokes Raman scattering (CARS) microscope based on a 2-MHz repetition rate ytterbium laser generating 1035-nm high-energy (≈µJ level) femtosecond pulses. These features of the driving laser allow producing broadband red-shifted Stokes pulses, covering the whole fingerprint region (400-1800 cm-1), employing supercontinuum generation in a bulk crystal. Our system reaches state-of-the-art acquisition speed (<1 ms/pixel) and unprecedented sensitivity of ≈14.1 mmol/L when detecting dimethyl sulfoxide in water. To further improve the performance of the system and to enhance the signal-to-noise ratio of the CARS spectra, we designed a convolutional neural network for spectral denoising, coupled with a post-processing pipeline to distinguish different chemical species of biological tissues

Noninvasive morpho-molecular imaging reveals early therapy-induced senescence in human cancer cells

Anticancer therapy screening in vitro identifies additional treatments and improves clinical outcomes. Systematically, although most tested cells respond to cues with apoptosis, an appreciable portion enters a senescent state, a critical condition potentially driving tumor resistance and relapse. Conventional screening protocols would strongly benefit from prompt identification and monitoring of therapy-induced senescent (TIS) cells in their native form. We combined complementary all-optical, label-free, and quantitative microscopy techniques, based on coherent Raman scattering, multiphoton absorption, and interferometry, to explore the early onset and progression of this phenotype, which has been understudied in unperturbed conditions. We identified TIS manifestations as early as 24 hours following treatment, consisting of substantial mitochondrial rearrangement and increase of volume and dry mass, followed by accumulation of lipid vesicles starting at 72 hours. This work holds the potential to affect anticancer treatment research, by offering a label-free, rapid, and accurate method to identify initial TIS in tumor cells

Full-Spectrum CARS Microscopy of Cells and Tissues with Ultrashort White-Light Continuum Pulses

Coherent anti-StokesRaman scattering (CARS) microscopyis an emergingnonlinear vibrational imaging technique that delivers label-free chemicalmaps of cells and tissues. In narrowband CARS, two spatiotemporallysuperimposed picosecond pulses, pump and Stokes, illuminate the sampleto interrogate a single vibrational mode. Broadband CARS (BCARS) combinesnarrowband pump pulses with broadband Stokes pulses to record broadvibrational spectra. Despite recent technological advancements, BCARSmicroscopes still struggle to image biological samples over the entireRaman-active region (400-3100 cm(-1)). Here,we demonstrate a robust BCARS platform that answers this need. Oursystem is based on a femtosecond ytterbium laser at a 1035 nm wavelengthand a 2 MHz repetition rate, which delivers high-energy pulses usedto produce broadband Stokes pulses by white-light continuum generationin a bulk YAG crystal. Combining such pulses, pre-compressed to sub-20fs duration, with narrowband pump pulses, we generate a CARS signalwith a high (<9 cm(-1)) spectral resolution inthe whole Raman-active window, exploiting both the two-color and three-colorexcitation mechanisms. Aided by an innovative post-processing pipeline,our microscope allows us to perform high-speed (approximate to 1 ms pixeldwell time) imaging over a large field of view, identifying the mainchemical compounds in cancer cells and discriminating tumorous fromhealthy regions in liver slices of mouse models, paving the way forapplications in histopathological settings