A cellulose monolithic stir bar for sorptive extraction of glycerol from biodiesel.

This work presents an eco-friendly approach for determining free glycerol in biodiesel samples, using a cellulose monolith stir bar in the sorptive extraction method with analysis by high-performance liquid chromatography and a refractive index detector. The cellulose monolith was produced from cellulose acetate by non-solvent-induced phase separation and subsequent alkaline deacetylation. The cellulose monolith presented a hierarchically porous structure, with 68% porosity and almost total deacetylation, with morphological and polarity characteristics that favor an efficient extraction of free glycerol from biodiesel. The sorptive extraction method using a cellulose monolith stir bar was optimized, obtaining a total extraction time of 30 min at 70 °C, using ultrapure water as the desorption solvent, and extraction of free glycerol of 93.6 ± 2.3%. The proposed method showed selectivity in free glycerol extraction, with limits of detection and quantification of 6.60 × 10-5% w/w and 2.18 × 10-4% w/w, respectively. Compared with the official reference method, the proposed one presented similar precision and accuracy, with few manipulations and any reagent/solvents. Furthermore, it is compatible with the principles of green chemistry and can be considered an eco-friendly method for determining free glycerol in biodiesel.

Curcumin and omega-3 polyunsaturated fatty acids as bioactive food components with synergistic effects on Alzheimer's disease.

Curcumin and omega-3 polyunsaturated fatty acids (ω-3 PUFA) are multifunctional compounds which play an important role in Alzheimer's disease (AD) and little has been addressed about the role of these two compounds together in the progression of the disease. There is evidence of the beneficial effect of combined administration of ω-3 PUFA and other dietary supplements such as vitamins and polyphenols in the prevention of AD, although much remains to be understood about their possible complementary or synergistic activity. Therefore, the objective of this work is to review the research focused on studying the effect and mechanisms of action of curcumin, ω-3 PUFA, and the combination of these nutraceutical compounds, particularly on AD, and to integrate the possible ways in which these compounds can potentiate their effect. The most important pathophysiologies that manifest in AD will be addressed, in order to have a better understanding of the mechanisms of action through which these bioactive compounds exert a neuroprotective effect.

Superoxide dismutase 2 deficiency is associated with enhanced central chemoreception in mice: Implications for breathing regulation.

AIMS: In mammals, central chemoreception plays a crucial role in the regulation of breathing function in both health and disease conditions. Recently, a correlation between high levels of superoxide anion (O2.-) in the Retrotrapezoid nucleus (RTN), a main brain chemoreceptor area, and enhanced central chemoreception has been found in rodents. Interestingly, deficiency in superoxide dismutase 2 (SOD2) expression, a pivotal antioxidant enzyme, has been linked to the development/progression of several diseases. Despite, the contribution of SOD2 on O2.- regulation on central chemoreceptor function is unknown. Accordingly, we sought to determine the impact of partial deletion of SOD2 expression on i) O2.-accumulation in the RTN, ii) central ventilatory chemoreflex function, and iii) disordered-breathing. Finally, we study cellular localization of SOD2 in the RTN of healthy mice. METHODS: Central chemoreflex drive and breathing function were assessed in freely moving heterozygous SOD2 knockout mice (SOD2+/- mice) and age-matched control wild type (WT) mice by whole-body plethysmography. O2.- levels were determined in RTN brainstem sections and brain isolated mitochondria, while SOD2 protein expression and tissue localization were determined by immunoblot, RNAseq and immunofluorescent staining, respectively. RESULTS: Our results showed that SOD2+/- mice displayed reductions in SOD2 levels and high O2.- formation and mitochondrial dysfunction within the RTN compared to WT. Additionally, SOD2+/- mice displayed a heightened ventilatory response to hypercapnia and exhibited overt signs of altered breathing patterns. Both, RNAseq analysis and immunofluorescence co-localization studies showed that SOD2 expression was confined to RTN astrocytes but not to RTN chemoreceptor neurons. Finally, we found that SOD2+/- mice displayed alterations in RTN astrocyte morphology compared to RTN astrocytes from WT mice. INNOVATION & CONCLUSION: These findings provide first evidence of the role of SOD2 in the regulation of O2.- levels in the RTN and its potential contribution on the regulation of central chemoreflex function. Our results suggest that reductions in the expression of SOD2 in the brain may contribute to increase O2.- levels in the RTN being the outcome a chronic surge in central chemoreflex drive and the development/maintenance of altered breathing patterns. Overall, dysregulation of SOD2 and the resulting increase in O2.- levels in brainstem respiratory areas can disrupt normal respiratory control mechanisms and contribute to breathing dysfunction seen in certain disease conditions characterized by high oxidative stress.

Larval Rearing and Nutrition of the Polyphagous Tephritid Pest Anastrepha ludens on Artificial Diets with Calcium Alginate, Agar, or Carrageenan as Gelling Agents at Various Concentrations and across Extreme Larval Density Conditions.

Research on larval rearing and nutrition of tephritid flies on artificial diets is key for the sterile insect technique. Here, we examined the effects of the type of gel (calcium alginate, agar, or carrageenan), at varying percentages in artificial diets for the polyphagous pest Anastrepha ludens, on the physicochemical and nutritional traits of the diets, and the effects of the type of gel, the gel content and the larval density (larvae/g of diet) used in production, quality parameters for mass-reared tephritids, diet removal (an indirect estimation of diet consumption), and nutritional traits of flies. Regardless of the gel content, calcium alginate diets were firmer and more resistant to penetration than the agar and carrageenan diets. The larval recovery, pupation, pupal weight, and flight ability of A. ludens were lower in calcium alginate diets than in agar and carrageenan diets. Diet removal was higher in calcium alginate diets; however, low levels of ammonium and high levels of uric acid in excretions from larvae on these diets suggest an alteration in protein metabolism. The firmness and penetration resistance characteristics of calcium alginate diets may have limited movement and feeding of larvae, but this could be overcome by the collective feeding of large groups of larvae. Our findings provide insights into the mechanism governing gel-diet rearing systems for A. ludens.

Nanosuspensions as carriers of active ingredients: Chemical composition, development methods, and their biological activities.

Nanosuspensions (NSps) are colloidal dispersions of particles that have the potential to solve the delivery problems of active ingredients associated with their low solubility in water or instability due to environmental factors. It is essential to consider their chemical composition and preparation methods because they directly influence drug loading, size, morphology, solubility, and stability; these characteristics of nanosuspensions influence the delivery and bioavailability of active ingredients. NSps provides high loading of drugs, protection against degrading agents, rapid dissolution, high particle stability, and high bioavailability of active ingredients across biological membranes. In addition, they provide lower toxicity compared to other nanocarriers, such as liposomes or polymeric nanoparticles, and can modify the pharmacokinetic profiles, thus improving their safety and efficacy. The present review aims to address all aspects related to the composition of NSps, the different methods for their production, and the main factors affecting their stability. Moreover, recent studies are described as carriers of active ingredients and their biological activities.

Interlaminar endoscopic uniportal approach for implantation of a paddle lead larger than 10 mm for spinal cord stimulation: illustrative case.

BACKGROUND: The authors aim to describe a new technique for implantation of a spinal cord stimulation paddle lead sized over 10 mm through an endoscopic uniportal approach. A new endoscopic cannula was developed for the passage of a paddle lead width between 10 and 13 mm. The distal portion of the cannula was designed with a larger opening, providing better visibility of the anterior portion of the adjacent structures, thus allowing a panoramic view of the electrode passage. An electrode was implanted in an 11-mm paddle. OBSERVATIONS: After searching PubMed, Cochrane, and Lilacs databases, the authors found no mention of the implantation of a paddle electrode with a width greater than 10 mm. The implantation of a paddle electrode less than 10 mm wide is possible via endoscopic access using 10-mm working channels. However, for electrodes with a width greater than 10 mm, access via endoscopy is impossible, since the working channel is only 10 mm. LESSONS: The authors concluded that it is possible to pass electrodes safely and effectively with a paddle width between 10 and 13 mm using spinal endoscopy via uniportal interlaminar access. However, it is necessary to expand studies to elucidate this technique of endoscopic implantation of electrodes for neurostimulation.

Transformers for Energy Forecast.

Forecasting energy consumption models allow for improvements in building performance and reduce energy consumption. Energy efficiency has become a pressing concern in recent years due to the increasing energy demand and concerns over climate change. This paper addresses the energy consumption forecast as a crucial ingredient in the technology to optimize building system operations and identifies energy efficiency upgrades. The work proposes a modified multi-head transformer model focused on multi-variable time series through a learnable weighting feature attention matrix to combine all input variables and forecast building energy consumption properly. The proposed multivariate transformer-based model is compared with two other recurrent neural network models, showing a robust performance while exhibiting a lower mean absolute percentage error. Overall, this paper highlights the superior performance of the modified transformer-based model for the energy consumption forecast in a multivariate step, allowing it to be incorporated in future forecasting tasks, allowing for the tracing of future energy consumption scenarios according to the current building usage, playing a significant role in creating a more sustainable and energy-efficient building usage.

Development of nanostructured formulation from naringenin and silk fibroin and application for inhibition of lipoxygenase (LOX).

A simple low-energy method was used to obtain polymeric nanoparticles containing silk fibroin (SF), fatty butyl esters (oily phase) and the flavonoid naringenin. Experimental planning (Box-Behnken) was applied to investigate the optimal conditions for three factors (variation of the concentrations of SF, naringenin and fatty butyl ester) at three levels, with evaluation of particle size, polydispersity index (PDI) and zeta potential (ZP) as responses. The results showed that the polymeric particle was formed with sizes of 179.6 to 633.9 nm, PDI of 0.33 to 0.77 and ZP of -60.4 to -38.8 mV. The best responses under the optimized conditions (Nari-SF 9 and 15) were characterized through transmission electron microscopy (TEM), Fourier-transform infrared (FT-IR), visible ultraviolet (UV-vis) and fluorescence, which confirmed that coated nanoparticles had been obtained. It was shown that the nanoformulation had excellent stability, the bioavailability of naringenin had been improved through use of the biopolymer and high inhibition of the enzyme lipoxygenase had been achieved in vitro.

Chronic intermittent hypoxia promotes glomerular hyperfiltration and potentiates hypoxia-evoked decreases in renal perfusion and PO2.

Introduction: Sleep apnea (SA) is highly prevalent in patients with chronic kidney disease and may contribute to the development and/or progression of this condition. Previous studies suggest that dysregulation of renal hemodynamics and oxygen flux may play a key role in this process. The present study sought to determine how chronic intermittent hypoxia (CIH) associated with SA affects regulation of renal artery blood flow (RBF), renal microcirculatory perfusion (RP), glomerular filtration rate (GFR), and cortical and medullary tissue PO2 as well as expression of genes that could contribute to renal injury. We hypothesized that normoxic RBF and tissue PO2 would be reduced after CIH, but that GFR would be increased relative to baseline, and that RBF, RP, and tissue PO2 would be decreased to a greater extent in CIH vs. sham during exposure to intermittent asphyxia (IA, FiO2 0.10/FiCO2 0.03). Additionally, we hypothesized that gene programs promoting oxidative stress and fibrosis would be activated by CIH in renal tissue. Methods: All physiological variables were measured at baseline (FiO2 0.21) and during exposure to 10 episodes of IA (excluding GFR). Results: GFR was higher in CIH-conditioned vs. sham (p < 0.05), whereas normoxic RBF and renal tissue PO2 were significantly lower in CIH vs. sham (p < 0.05). Reductions in RBF, RP, and renal tissue PO2 during IA occurred in both groups but to a greater extent in CIH (p < 0.05). Pro-oxidative and pro-fibrotic gene programs were activated in renal tissue from CIH but not sham. Conclusion: CIH adversely affects renal hemodynamic regulation and oxygen flux during both normoxia and IA and results in changes in renal tissue gene expression.

Potential probiotic lactobacilli strains isolated from artisanal Mexican Cocido cheese: evidence-based biosafety and probiotic action-related traits on in vitro tests.

The biosafety of four potentially probiotic lactobacilli strains, isolated from artisanal Mexican Cocido cheese, was assessed through in vitro tests aimed to determine (1) the antibiotic susceptibility profile by broth microdilution, (2) the transferability of antibiotic resistance determinants by filter-mating, and (3) the phenotypic and genotypic stability during serial batch sub-culture (100-day period) by evaluating physiological and probiotic features and RAPD-PCR fingerprinting. Lactobacilli strains exhibited multidrug-resistance; however, resistance determinants were not transferred in the filter-mating assay. Significant (p < 0.05) differences were observed in bacterial morphology and some functional and technological properties when strains were serially sub-cultured over 50 generations (G50), compared to the initial cultures (G0). Conversely, the strains did not show mucinolytic and hemolytic activities either at G0 or after 100 generations (G100). Genetic polymorphism and genomic template instability on selected strains were detected, which suggest possible evolutionary arrangements that may occur when these bacteria are largely cultured. Our findings suggest that the assessed strains did not raise in vitro biosafety concerns; however, complementary studies are still needed to establish the safe potential applications in humans and animals.

Enhanced Peripheral Chemoreflex Drive Is Associated with Cardiorespiratory Disorders in Mice with Coronary Heart Disease.

Coronary heart disease (CHD) is a prevalent cardiovascular disease characterized by coronary artery blood flow reductions caused by lipid deposition and oxidation within the coronary arteries. Dyslipidemia is associated with local tissue damage by oxidative stress/inflammation and carotid bodies (CB) peripheral chemoreceptors are heavily modulated by both reactive oxygen species and pro-inflammatory molecules (i.e., cytokines). Despite this, it is not know whether CB-mediated chemoreflex drive may be affected in CHD. In the present study, we evaluated peripheral CB-mediated chemoreflex drive, cardiac autonomic function, and the incidence of breathing disorders in a murine model of CHD. Compared to age-matched control mice, CHD mice showed enhanced CB-chemoreflex drive (twofold increase in the hypoxic ventilatory response), cardiac sympathoexcitation, and irregular breathing disorders. Remarkably, all these were closely linked to the enhanced CB-mediated chemoreflex drive. Our results showed that mice with CHD displayed an enhanced CB chemoreflex, sympathoexcitation, and disordered breathing and suggest that CBs may be involved in chronic cardiorespiratory alterations in the setting of CHD.

Acoustic partitioning explains the coexistence between two Physalaemus species (Anura, Leptodactylidae) in the Atlantic Forest in Eastern Bahia State, Brazil.

In this study we investigate the niche interaction between the frogs Physalameus cuvieri and Physalaemus kroyeri that occur in syntopy in water bodies of the Atlantic Forest located in the eastern Bahia State, Brazil. We investigated the niche width and overlap in the calling activity time, microhabitat use, diet composition, advertisement call, and body size. Both species preferred the same substrate and calling substrate categories, and showed low niche width values and high spatial niche overlap values. The pseudocommunity analysis revealed the absence of competition in space use. Ants and termites were the most important items in the diet of both species with the pseudocommunity analysis indicating an absence of competition in the diet. The two species demonstrate a greater similarity in body proportions and a high overlap in the calling activity time. However, they showed divergence in acoustic parameters, especially in the dominant frequency and call duration. Our results reinforce the role of advertisement call as a relevant attribute for anuran coexistence and highlight the importance of analyzing the various axes of the multidimensional niche for the most reliable description of the existence and magnitude of niche partitioning.

Particulate air pollution in the Copenhagen metro part 1: Mass concentrations and ventilation.

The Copenhagen Metro comprises four lines, the M1, M2, M3 and M4, with 25 subterranean stations and an additional 14 stations above ground, serving ca. 80 million passengers annually. In this study we measure fine particulate matter (PM2.5) and carbon dioxide (CO2) concentrations in stations and in trains across the entire system. In partially underground lines, high PM2.5 concentrations with an average of 109 µg m-3 are found in below-ground stations. The observed correlation between PM2.5 concentration and distance between a station and a tunnel exit is attributed to ventilation via the piston effect. The piston effect via tunnel draught relief shafts was therefore found to be relatively limited. Filter samples of particulate matter are analysed using particle-induced X-ray emission and show an iron content of 88.6 % by mass which is quite different from above-ground particulate matter and consistent with particle production by train wheels, rails and brakes. The average concentration measured at the stations of a recently opened (2019) fully underground M3 closed loop line is 168 µg m-3, further demonstrating that while piston effect-driven ventilation is effective in close proximity to tunnel openings, it is relatively limited via tunnel draught relief shafts. Measurements onboard trains show even higher PM2.5 concentrations and the patterns in CO2 concentrations suggest carriage ventilation by tunnel air. Ventilation via doors during platform stops caused a drop in observed PM (and CO2) at stations, but the system is surprisingly polluted despite its recent construction. CO2 mixing ratios ranged from ambient to around 600 ppm. Measures should be taken to control PM levels using a combination of source control and increased clean air supply of the Copenhagen and other similar metro systems.

Antioxidant addition improves cholesterol and astaxanthin stability in dry salted shrimp.

BACKGROUND: Traditional production of dry salted shrimp enhances cholesterol oxidation and astaxanthin degradation in the product. The aim of this study was to evaluate the effect of addition of the antioxidants butylhydroxytoluene (BHT) and tert-butylhydroquinone (TBHQ) to cooked shrimp on the formation of cholesterol oxidation products (COPs) and astaxanthin degradation during solar drying of shrimp. RESULTS: The added antioxidants significantly inhibited COPs formation after the product was boiled in brine. Smaller amounts of COPs were formed in antioxidant-treated shrimps (~-23%) as compared to untreated samples. The antioxidants continued to significantly inhibit COPs formation (~-39%) during sun drying. Similarly, TBHQ and BHT reduced by 51.3% and 37.2%, respectively, the degradation rate of astaxanthin, favoring a higher retention of this carotenoid in the final product. CONCLUSION: The use of the antioxidants BHT and TBHQ in the preparation of dry salted shrimp significantly inhibited the formation of COPs after cooking raw shrimp and during direct solar drying. They also protected astaxanthin contained in the cooked shrimp from photodegradation. These results are technologically relevant because it is possible to prepare a product with a higher content of astaxanthin and lower the presence of hazardous COPs. © 2022 Society of Chemical Industry.

Key Stress Response Mechanisms of Probiotics During Their Journey Through the Digestive System: A Review.

The survival of probiotic microorganisms during their exposure to harsh environments plays a critical role in the fulfillment of their functional properties. In particular, transit through the human gastrointestinal tract (GIT) is considered one of the most challenging habitats that probiotics must endure, because of the particularly stressful conditions (e.g., oxygen level, pH variations, nutrient limitations, high osmolarity, oxidation, peristalsis) prevailing in the different sections of the GIT, which in turn can affect the growth, viability, physiological status, and functionality of microbial cells. Consequently, probiotics have developed a series of strategies, called "mechanisms of stress response," to protect themselves from these adverse conditions. Such mechanisms may include but are not limited to the induction of new metabolic pathways, formation/production of particular metabolites, and changes of transcription rates. It should be highlighted that some of such mechanisms can be conserved across several different strains or can be unique for specific genera. Hence, this review attempts to review the state-of-the-art knowledge of mechanisms of stress response displayed by potential probiotic strains during their transit through the GIT. In addition, evidence whether stress responses can compromise the biosafety of such strains is also discussed.

Safety Assessment of the Potential Probiotic Bacterium Limosilactobacillus fermentum J23 Using the Mexican Fruit Fly (Anastrepha ludens Loew, Diptera: Tephritidae) as a Novel In Vivo Model.

Safety assessment of probiotics is difficult but essential. In this work, the Mexican fruit fly, Anastrepha ludens (Loew) (Diptera: Tephritidae), was used as in vivo model to assess the biosafety of Limosilactobacillus fermentum J23. In the first set of experiments, the strain was orally administered to adult flies through direct feeding, whereas in the second set of experiments, it was supplemented through the larval rearing medium. Data showed that L. fermentum J23 did not lead to increased mortality or treatment-related toxicity signs in adult female and male flies. Ingestion of L. fermentum J23 by adult female flies led to a statistically significant improvement in locomotor activity compared to the control groups (ca. 59% decrease in climbing time, p < 0.0001). A positive trend in lifespan extension under stress (maximum lifespan = 144 h) was also observed. When L. fermentum J23 was administered to the larvae, the adult emergence (p = 0.0099), sex ratio (p = 0.0043), and flight ability (p = 0.0009) increased significantly by 7%, 31%, and 8%, respectively, compared to the control diet. No statistical effect between the control diet and the L. fermentum J23-based diet for the number of pupae recovered, pupal weight, duration of the pupal stage, lifespan under stress, and morphological development was observed. We conclude that feeding L. fermentum J23 to the novel experimental model A. ludens had no toxic effects and could be safely considered a potential probiotic for food supplements; however, further studies are still needed to establish its biosafety in humans.

Diagnóstico prenatal de enfermedad de canal atrio-ventricular, análisis epidemiológico y experiencia CERPO entre 2003 y 2021 / Prenatal diagnosis of atrio-ventricular canal disease, epidemiological analysis and CERPO experience between 2003 and 2021

Antecedentes: En Chile, la mitad de los casos de mortalidad perinatal son atribuibles a anomalías congénitas, y un tercio de estas corresponde a cardiopatías congénitas. Aproximadamente un 35% de estos últimos requerirán cirugía antes del año de vida, por lo que la pesquisa prenatal impacta profundamente en el pronóstico. Objetivo: Dar a conocer los resultados perinatales de pacientes con diagnóstico prenatal de canal atrio-ventricular controlados en el Centro de Referencia Perinatal Oriente (CERPO) entre los años 2003 y 2021, su asociación a otras anomalías, características demográficas y pronóstico a un año. Métodos: En este estudio se puede apreciar que tanto el pronóstico como el plan terapéutico posnatal dependerán de la presencia de otras alteraciones morfológicas y del estudio genético. De los factores estudiados, se puede concluir que tanto la presencia de anomalías cardiacas asociadas, como el grado de insuficiencia valvular y el tipo de canal no son predictores de la sobrevida perinatal. Conclusiones: Finalmente, en relación con la sobrevida posnatal, en este estudio, la sobrevida a un año de los recién nacidos vivos fue de un 52%, pero al desglosarlo en los niños con cariotipo euploide y trisomía 21, estos valores se tornan muy distintos, 44 y 81% respectivamente.

Background: In Chile, half of the perinatal mortality cases are attributable to congenital anomalies, and one third of these correspond to congenital heart disease. Approximately 35% of the later will require surgery before one year of life, so prenatal screening has a profound impact on the prognosis. Objective: To present the perinatal results of patients with a prenatal diagnosis of atrio-ventricular canal controlled at Centro de Referencia Perinatal Oriente CERPO) between 2003 and 2021, its association with other anomalies, demographic characteristics, and 1-year prognosis. Methods: In this study it can be seen that both the prognosis and the postnatal therapeutic plan will depend on the presence of other morphological alterations and the genetic study. From the factors studied, it can be concluded that the presence of associated cardiac anomalies, the degree of valvular insufficiency, and the type of canal are not predictors of perinatal survival. Conclusions: Finally, in relation to postnatal survival, in this study, the 1-year survival of live newborns was 52%, but when broken down into children with euploid karyotype and trisomy 21, these values become very different, 44 and 81% respectively.

Anesthetic Management and Considerations for Electrophysiology Procedures.

The number of electrophysiology (EP) procedures being performed has dramatically increased in recent years. This escalation necessitates a full understanding by the general anesthesiologist as to the risks, specific considerations, and comorbidities that accompany these now common procedures. Procedures reviewed in this article include atrial fibrillation and flutter ablation, supraventricular tachycardia ablation, ventricular tachycardia ablation, electrical cardioversion, pacemaker insertion, implantable cardioverter-defibrillator (ICD) insertion, and ICD lead extraction. General anesthetic considerations as well as procedure-specific concerns are discussed. Knowledge of these procedures will add to the anesthesiologist's armamentarium in safely caring for patients in the EP laboratory.

Sound Classification and Processing of Urban Environments: A Systematic Literature Review.

Audio recognition can be used in smart cities for security, surveillance, manufacturing, autonomous vehicles, and noise mitigation, just to name a few. However, urban sounds are everyday audio events that occur daily, presenting unstructured characteristics containing different genres of noise and sounds unrelated to the sound event under study, making it a challenging problem. Therefore, the main objective of this literature review is to summarize the most recent works on this subject to understand the current approaches and identify their limitations. Based on the reviewed articles, it can be realized that Deep Learning (DL) architectures, attention mechanisms, data augmentation techniques, and pretraining are the most crucial factors to consider while creating an efficient sound classification model. The best-found results were obtained by Mushtaq and Su, in 2020, using a DenseNet-161 with pretrained weights from ImageNet, and NA-1 and NA-2 as augmentation techniques, which were of 97.98%, 98.52%, and 99.22% for UrbanSound8K, ESC-50, and ESC-10 datasets, respectively. Nonetheless, the use of these models in real-world scenarios has not been properly addressed, so their effectiveness is still questionable in such situations.

Transformers for Urban Sound Classification-A Comprehensive Performance Evaluation.

Many relevant sound events occur in urban scenarios, and robust classification models are required to identify abnormal and relevant events correctly. These models need to identify such events within valuable time, being effective and prompt. It is also essential to determine for how much time these events prevail. This article presents an extensive analysis developed to identify the best-performing model to successfully classify a broad set of sound events occurring in urban scenarios. Analysis and modelling of Transformer models were performed using available public datasets with different sets of sound classes. The Transformer models' performance was compared to the one achieved by the baseline model and end-to-end convolutional models. Furthermore, the benefits of using pre-training from image and sound domains and data augmentation techniques were identified. Additionally, complementary methods that have been used to improve the models' performance and good practices to obtain robust sound classification models were investigated. After an extensive evaluation, it was found that the most promising results were obtained by employing a Transformer model using a novel Adam optimizer with weight decay and transfer learning from the audio domain by reusing the weights from AudioSet, which led to an accuracy score of 89.8% for the UrbanSound8K dataset, 95.8% for the ESC-50 dataset, and 99% for the ESC-10 dataset, respectively.