Comprehensive Review: Machine and Deep Learning in Brain Stroke Diagnosis.

Brain stroke, or a cerebrovascular accident, is a devastating medical condition that disrupts the blood supply to the brain, depriving it of oxygen and nutrients. Each year, according to the World Health Organization, 15 million people worldwide experience a stroke. This results in approximately 5 million deaths and another 5 million individuals suffering permanent disabilities. The complex interplay of various risk factors highlights the urgent need for sophisticated analytical methods to more accurately predict stroke risks and manage their outcomes. Machine learning and deep learning technologies offer promising solutions by analyzing extensive datasets including patient demographics, health records, and lifestyle choices to uncover patterns and predictors not easily discernible by humans. These technologies enable advanced data processing, analysis, and fusion techniques for a comprehensive health assessment. We conducted a comprehensive review of 25 review papers published between 2020 and 2024 on machine learning and deep learning applications in brain stroke diagnosis, focusing on classification, segmentation, and object detection. Furthermore, all these reviews explore the performance evaluation and validation of advanced sensor systems in these areas, enhancing predictive health monitoring and personalized care recommendations. Moreover, we also provide a collection of the most relevant datasets used in brain stroke analysis. The selection of the papers was conducted according to PRISMA guidelines. Furthermore, this review critically examines each domain, identifies current challenges, and proposes future research directions, emphasizing the potential of AI methods in transforming health monitoring and patient care.

Validation of an FT-IR microscopy method for the monitorization of microplastics in water for human consumption in Portugal: Lisbon case study.

The growing anthropogenic contamination of natural water by microplastics (MPs) confirms the urgent need to preserve this precious resource. MPs are part of the group of contaminants of emerging concern, and the occurrence studies in surface water and water for human consumption (WHC) are mandatory for environmental and human health risk assessment. This study aims to optimize and validate a Fourier transform infrared spectroscopy method coupled with optical microscopy (micro-FTIR) in transmission mode to monitor MPs in WHC. Water sample (250 mL; without sample pre-treatment) was filtered through 5 µm silicon filters. The infrared spectra identification was performed by OMNIC mathematical correlation, using various spectra libraries for polymers (including the in-house IR spectra library), a background reading on a clean silicon filter, and an aperture of 100 µm × 100 µm. The validated method showed good accuracy, with an average recovery for representative polymers of 91%, a relative standard deviation of 13%, and a reporting limit (RL) of 44 MPs/L. Sixty WHC samples from the Lisbon water supply system showed MPs ranging from 0 (< RL) to 934 MPs/L, with an average value of 309 MPs/L. The most representative polymers were polyethylene (PE, 76.8%), polyethylene terephthalate (PET, 6.9%), polypropylene (PP, 6%), polystyrene (PS, 4%), and polyamide (PA,4%). In terms of size, the microplastic particles had an average length and width of 76 µm and 39 µm, respectively.

Erratum: Black Holes in an Effective Field Theory Extension of General Relativity [Phys. Rev. Lett. 121, 251105 (2018)].

This corrects the article DOI: 10.1103/PhysRevLett.121.251105.

Energy Extraction from Q-balls and Other Fundamental Solitons.

Energy exchange mechanisms have important applications in particle physics, gravity, fluid mechanics, and practically every field in physics. In this Letter we show, both in the frequency and time domain, that energy enhancement is possible for waves scattering off fundamental solitons (time-periodic localized structures of bosonic fields), without the need for rotation nor translational motion. We use two-dimensional Q-balls as a test bed, providing the correct criteria for energy amplification, as well as the respective amplification factors, and we discuss possible instability mechanisms. Our results lend support to the qualitative picture drawn in Saffin et al. [preceding Letter, Q-ball superradiance, Phys. Rev. Lett. 131, 111601 (2023).PRLTAO0031-900710.1103/PhysRevLett.131.111601]; however, we show that this enhancement mechanism is not of superradiant type, but instead is a "blueshiftlike" energy exchange between scattering states induced by the background Q-ball, which should occur generically for any time-periodic fundamental soliton. This mechanism does not seem to lead to instabilities.

Photon Ring Astrometry for Superradiant Clouds.

Gravitational atoms produced from the superradiant extraction of rotational energy of spinning black holes can reach energy densities significantly higher than that of dark matter, turning black holes into powerful potential detectors for ultralight bosons. These structures are formed by coherently oscillating bosons, which induce oscillating metric perturbations deflecting photon geodesics passing through their interior. The deviation of nearby geodesics can be further amplified near critical bound photon orbits. We discuss the prospect of detecting this deflection using photon ring autocorrelations with the Event Horizon Telescope and its next-generation upgrade, which can probe a large unexplored region of the cloud mass parameter space when compared with previous constraints.

Nonlinear Effects in Black Hole Ringdown.

We report evidence for nonlinear modes in the ringdown stage of the gravitational waveform produced by the merger of two comparable-mass black holes. We consider both the coalescence of black hole binaries in quasicircular orbits and high-energy, head-on black hole collisions. The presence of nonlinear modes in the numerical simulations confirms that general-relativistic nonlinearities are important and must be considered in gravitational-wave data analysis.

Different approaches for estimation of the expanded uncertainty of an analytical method developed for determining pharmaceutical active compounds in wastewater using solid-phase extraction and a liquid chromatography coupled with tandem mass spectrometry method.

Although the evaluation of the uncertainty of an analytical method is a mandatory step in the method's validation, its applicability to the monitoring of trace compounds in complex samples is not simple, nor is it part of the routine of most laboratories, namely those dedicated to research. This manuscript focuses on the full validation of an analytical procedure for determining trace concentrations of twenty-four pharmaceutical active compounds (PhACs) in wastewaters using solid-phase extraction (SPE) and ultra-high performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS). The method optimization was performed on different wastewater matrices, namely influents and final effluents from two distinct wastewater treatment plants (WWTPs). Matrix effects and extraction efficiency (absolute recovery) of the developed method were determined. Validation was performed to obtain the method's linearity/working range, precision, trueness, method detection limits (MDLs) and method quantification limits (MQLs). The expanded uncertainty of the data obtained was estimated according to the requirements of international procedures dedicated to the expression of uncertainty. Different approaches for the estimation of uncertainty were applied. The validated method was used in the analysis of target PhACs in wastewater samples collected at two WWTPs. The obtained results facilitated the introduction of a validated method for routine measurement of PhACs in wastewater samples and allowed method accreditation by the competent national authority.

Gravitational Waves from Extreme-Mass-Ratio Systems in Astrophysical Environments.

We establish a generic, fully relativistic formalism to study gravitational-wave emission by extreme-mass-ratio systems in spherically symmetric, nonvacuum black hole spacetimes. The potential applications to astrophysical setups range from black holes accreting baryonic matter to those within axionic clouds and dark matter environments, allowing one to assess the impact of the galactic potential, of accretion, gravitational drag, and halo feedback on the generation and propagation of gravitational waves. We apply our methods to a black hole within a halo of matter. We find fluid modes imparted to the gravitational-wave signal (a clear evidence of the black hole fundamental mode instability) and the tantalizing possibility to infer galactic properties from gravitational-wave measurements by sensitive, low-frequency detectors.

Development of multi-residue gas chromatography coupled with mass spectrometry methodologies for the measurement of 15 chemically different disinfection by-products (DBPs) of emerging concern in drinking water from two different Portuguese water treatment plants.

In water treatment plants (WTPs), chemical agents, such as chlorine and ozone, might react with organic matter and anthropogenic contaminants, forming a high diversity of disinfection by-products (DBPs). Due to the potential toxicological effects, the identification of unregulated DBPs (UR-DBPs) is critical to help water managers in the selection of effective water treatment processes, contributing to improving water safety plans. Given the limited validated analytical methods to detect UR-DBPs, here we developed new multi-residue gas chromatography coupled with mass spectrometry methodologies for the detection and quantification of 15 UR-DBPs, including aldehydes, haloketones (HKs), nitrosamines and alcohols, in drinking water matrices. Solid-phase extraction (SPE), for the nitrosamine group, and solid-phase micro extraction (SPME), for the remaining DBPs, were used as sample preparation methods. The developed methodologies allowed the quantification of target UR-DBPs at trace concentration levels (ng L-1), with method quantification limits (MQLs) ranging from 14.4 ng L-1 to 26.0 ng L-1 (SPE-GC-MS) and 2.3 ng L-1 and 1596 ng L-1 (SPME-GC-MS). The methods were applied to different drinking water matrices, considering distinct delivery points of EPAL - Empresa Portuguesa das Águas Livres WTPs. Overall, the aldehyde group, represented by decanal, nonanal and 2-ethylheaxanal, showed the highest occurrence, followed by HKs and nitrosamines. The results of this study suggested that the formation of these UR-DBPs should be further monitored in WTPs.

Analysis of Ringdown Overtones in GW150914.

We analyze GW150914 postmerger data to understand if ringdown overtone detection claims are robust. We find no evidence in favor of an overtone in the data after the waveform peak. Around the peak, the Bayes factor does not indicate the presence of an overtone, while the support for a nonzero amplitude is sensitive to changes in the starting time much smaller than the overtone damping time. This suggests that claims of an overtone detection are noise dominated. We perform GW150914-like injections in neighboring segments of the real detector noise, and we show that noise can indeed induce artificial evidence for an overtone.

Destabilizing the Fundamental Mode of Black Holes: The Elephant and the Flea.

Recent work applying the notion of pseudospectrum to gravitational physics showed that the quasinormal mode spectrum of black holes is unstable, with the possible exception of the longest-lived (fundamental) mode. The fundamental mode dominates the expected signal in gravitational wave astronomy, and there is no reason why it should have privileged status. We compute the quasinormal mode spectrum of two model problems where the Schwarzschild potential is perturbed by a small "bump" consisting of either a Pöschl-Teller potential or a Gaussian, and we show that the fundamental mode is destabilized under generic perturbations. We present phase diagrams and study a simple double-barrier toy problem to clarify the conditions under which the spectral instability occurs.

The effect of mission duration on LISA science objectives.

The science objectives of the LISA mission have been defined under the implicit assumption of a 4-years continuous data stream. Based on the performance of LISA Pathfinder, it is now expected that LISA will have a duty cycle of ≈ 0.75 , which would reduce the effective span of usable data to 3 years. This paper reports the results of a study by the LISA Science Group, which was charged with assessing the additional science return of increasing the mission lifetime. We explore various observational scenarios to assess the impact of mission duration on the main science objectives of the mission. We find that the science investigations most affected by mission duration concern the search for seed black holes at cosmic dawn, as well as the study of stellar-origin black holes and of their formation channels via multi-band and multi-messenger observations. We conclude that an extension to 6 years of mission operations is recommended.

Understanding the bioaccumulation of pharmaceutical active compounds by clams Ruditapes decussatus exposed to a UWWTP discharge.

Twenty-four pharmaceutical active compounds (PhACs) were evaluated in the soft tissues of clams Ruditappes decussatus exposed along a 1.5-km dispersal gradient of the treated effluent from an urban wastewater treatment plant discharging in Ria Formosa, and compared with those in the marine waters and discharged effluents. The clams were exposed for 1 month, in June-July 2016, 2017 and 2018. PhACs were quantified by high performance liquid chromatography coupled to tandem mass spectrometry after the quick, easy, cheap, effective, rugged and safe (QuEChERS) method (clams) or solid-phase extraction (water samples). The most representative PhACs in the effluents and receiving waters (regardless of the tidal dilution effect) were diclofenac, carbamazepine and caffeine (on average ≤ 2 µg/L) and only caffeine exhibited significant inter-annual differences, with higher values in 2017. In turn, the most bioaccumulated PhACs in clams were caffeine (0.54-27 ng/g wet weight, significantly higher in 2016) and acetaminophen (0.37-3.7 ng/g wet weight, significant lower in 2016). A multivariate principal component analysis showed (i) PhAC bioaccumulation primarily depended on biotic factors (clams length and weight), (ii) PhAC physicochemical properties Log Kow, pKa and water solubility interplaying with water abiotic variables were more relevant for explaining data variability in water than the physical dilution/tidal mixing, (iii) this process, reflected by the salinity gradient, had a tertiary role in data variation, responsible for spatial discrimination of marine waters. This study provides a better understanding of PhACs bioaccumulation by clams Ruditapes decussatus in real environmental conditions, under the influence of urban treated effluent dispersal in Ria Formosa coastal lagoon, a major producer of bivalves, ultimately disentangling key factors of PhAC bioaccumulation.

Assessment of Water Quality Parameters and their Seasonal Behaviour in a Portuguese Water Supply System: a 6-year Monitoring Study.

Water quality monitoring is a fundamental tool in the management of freshwater resources. The purpose of monitoring is to provide meaningful quality data for local action planning and catchment-wide decision making. The assessment of water quality is crucial to guarantee the efficient operation of the Water Treatment Plants (WTPs), promoting health conditions and contributing for a more sustainable urban water cycle. In accordance, the objective of this study was to evaluate key target chemical and microbiological water quality parameters, some of them already monitored within Portuguese/EU legal framework and others still not regulated, but with environmental and human heath relevance. A local monitoring database model, using a 6-year period (from 2014 to 2019) of water quality data, regarding water samples collected on representative sampling locations covering the freshwater abstraction sites, conventional WTPs and distribution network was assessed. This work provides new knowledge regarding occurrence and seasonal behaviour for both microbiological and chemical water quality parameters, essential to understand/manage the water supply system. Additionally, relationships between the target variables were also assessed. Particularly, strong correlations were identified between TOC and THMs formation at distribution network (r = 0.69; p ≤ 0.001); nitrates were the water quality parameter that revealed the best correlation between surface water source and treated water (r = 0.81; p ≤ 0.001), suggesting that treatment yield/performance is dependent on surface water load. The local and continuous monitoring of water systems are crucial to implement new approaches to guarantee the best quality of drinking water throughout the supply system.

Probing the nature of black holes: Deep in the mHz gravitational-wave sky.

Black holes are unique among astrophysical sources: they are the simplest macroscopic objects in the Universe, and they are extraordinary in terms of their ability to convert energy into electromagnetic and gravitational radiation. Our capacity to probe their nature is limited by the sensitivity of our detectors. The LIGO/Virgo interferometers are the gravitational-wave equivalent of Galileo's telescope. The first few detections represent the beginning of a long journey of exploration. At the current pace of technological progress, it is reasonable to expect that the gravitational-wave detectors available in the 2035-2050s will be formidable tools to explore these fascinating objects in the cosmos, and space-based detectors with peak sensitivities in the mHz band represent one class of such tools. These detectors have a staggering discovery potential, and they will address fundamental open questions in physics and astronomy. Are astrophysical black holes adequately described by general relativity? Do we have empirical evidence for event horizons? Can black holes provide a glimpse into quantum gravity, or reveal a classical breakdown of Einstein's gravity? How and when did black holes form, and how do they grow? Are there new long-range interactions or fields in our Universe, potentially related to dark matter and dark energy or a more fundamental description of gravitation? Precision tests of black hole spacetimes with mHz-band gravitational-wave detectors will probe general relativity and fundamental physics in previously inaccessible regimes, and allow us to address some of these fundamental issues in our current understanding of nature.

Instabilities of Scalar Fields around Oscillating Stars.

The behavior of fundamental fields in strong gravity or nontrivial environments is important for our understanding of nature. This problem has interesting applications in the context of dark matter, of dark energy physics, or of quantum field theory. The dynamics of fundamental fields has been studied mainly in static or stationary backgrounds, whereas most of our Universe is dynamic. In this Letter we investigate "blueshift" and parametric instabilities of scalar fields in dynamical backgrounds, which can be triggered (for instance) by oscillating stars in scalar-tensor theories of gravity. We discuss possible implications of our results, which include constraints on an otherwise hard-to-access parameter space of scalar-tensor theories.

Responses of benthic diatoms to waters affected by post-fire contamination.

Wildfire effects go beyond direct impact in terrestrial ecosystems. Specifically, the periphytic communities of aquatic ecosystems standing within and downstream the burnt areas are relevant ecological receptors of post-fire runoff contamination. Nevertheless, the off-site impacts of wildfires in these communities are limitedly studied so far. The present study aimed to assess the effects of river water contaminated with ash-loaded runoff in the growth benthic diatom Navicula libonensis (Schoeman 1970). Four surface water samples were collected approximately one year after the wildfire for laboratory testing with the diatom: one was collected from a site upstream the burnt area, within the Unhais river (UU); three were collected from sites standing within the burnt area, one in the Unhais river (UB) and two in the Zêzere river (Z1 and Z2), reflecting different hydrological regimes. N. libonensis was proven able to discriminate among river sites affected and unaffected by wildfire runoff, reflecting, in general, the expected trends considering the physico-chemical characterization of the water samples. The water samples from the sites standing within the burnt area inhibited the biomass yield and growth rate of the tested diatom, ranking the samples regarding toxicity as follows: Z1 > UB > Z2 > UU. However, UB rather than Z1 presented the highest contaminant burden, namely metal elements, and some were found above widely accepted safety benchmarks (polycyclic aromatic hydrocarbons were not detected). This inconsistency can be linked to unknown interactions among metals within each water sample, to differential nutrient enrichment of samples, as well as hydrological factors. Overall, our results suggest that monospecific laboratory assays with sensitive diatoms can be valuable as cost-effective screening tools to prioritize sites affected by wildfires runoff requiring in-depth monitoring of negative effects in benthic producer communities.

Screening and Seasonal Behavior of Analgesics, Non-steroidal Anti-inflammatory Drugs, and Antibiotics in Two Urban Wastewater Treatment Plants.

Pharmaceutical active compounds (PhACs) belonging to analgesics, antibiotics, and non-steroidal anti-inflammatory drugs (NSAIDs) therapeutic classes were monitored in wastewater influents and effluents from two Portuguese urban wastewater treatment plants (UWWTPs) for 24 months. Both facilities were chosen due to their effluents are discharged in highly touristic and sensitive areas, Tagus river and Ria Formosa coastal lagoon, respectively. Target PhACs, acetaminophen, diclofenac, ibuprofen, naproxen, sulfadiazine, and sulfamethoxazole were measured using solid-phase extraction (SPE) coupled to liquid chromatography tandem mass spectrometry (LC-MS/MS). PhACs occurrence in the influents was higher than 98%, with acetaminophen presenting the highest concentrations, with values between 16.3 µg/L and 124 µg/L. In the effluents, distinct behavior was observed with diclofenac and sulfamethoxazole showing recalcitrant characteristics, whereas acetaminophen, ibuprofen, and naproxen showed removal efficiencies above 95%. Acetaminophen and ibuprofen amount in influents showed consistently higher concentration levels in autumn (in Beirolas and Faro Nw UWWTPs) and winter (only in Beirolas UWWTP) seasons. These seasonal trends were observed to a greater extent in Beirolas UWWTP than in Faro Nw UWWTP. This study enabled the comprehensive definition of a behavior pattern for these target contaminants, contributing to better characterization and build-up a library of PhACs occurrence. It also allowed a robust seasonal profiling of the target compounds due to the high number of samples analyzed by each season and a longer monitoring campaign, making the obtained results more significant.

Study of the Potential of Water Treatment Sludges in the Removal of Emerging Pollutants.

Presently, water quantity and quality problems persist both in developed and developing countries, and concerns have been raised about the presence of emerging pollutants (EPs) in water. The circular economy provides ways of achieving sustainable resource management that can be implemented in the water sector, such as the reuse of drinking water treatment sludges (WTSs). This study evaluated the potential of WTS containing a high concentration of activated carbon for the removal of two EPs: the steroid hormones 17ß-estradiol (E2) and 17α-ethinylestradiol (EE2). To this end, WTSs from two Portuguese water treatment plants (WTPs) were characterised and tested for their hormone adsorbance potential. Both WTSs showed a promising adsorption potential for the two hormones studied due to their textural and chemical properties. For WTS1, the final concentration for both hormones was lower than the limit of quantification (LOQ). As for WTS2, the results for E2 removal were similar to WTS1, although for EE2, the removal efficiency was lower (around 50%). The overall results indicate that this method may lead to new ways of using this erstwhile residue as a possible adsorbent material for the removal of several EPs present in wastewaters or other matrixes, and as such contributing to the achievement of Sustainable Development Goals (SDG) targets.