The Reflections series takes a look back on historical articles from The Journal of the Acoustical Society of America that have had a significant impact on the science and practice of acoustics.
Acoustic mode decomposition is used for evaluating the damping of aircraft liners and, in general, to investigate acoustic scattering in flow ducts. Classical methods rely on analytical solutions of ...the wave properties and accept uncertainties due to simplified descriptions of the duct flow. In contrast, the current study provides a wave decomposition method that does not require explicit analytical knowledge of the wave properties and registers a wide range of flow-related acoustic phenomena. A multilayer perceptron artificial neural network is trained to learn acoustic wave decomposition for plane-wave-like duct modes. Training data are the numerical solutions of the Linearized Navier-Stokes Equations, from which the network not only learns the wave motion properties but also the dispersion of sound into the fluid flow. The network can account for flow-related effects, such as turbulent attenuation, refraction, convection, and thermo-viscous dissipation, which are only included in the classical models based on simplifications. The new method is validated for plane-waves against analytical data and experiments. It is demonstrated that the network can mimic the classical solutions accurately when trained under the same flow simplifications. In addition, it can cope with complex flow effects, such as turbulent attenuation, by including them in the training data. Therefore, the proposed wave decomposition complements the classical plane-wave decomposition when investigating in-duct sound with complex flow conditions. An important continuation of this work is to extend the new wave decomposition method to multi-modal sound fields. As the first step in this direction, it is demonstrated that the proposed training scheme also works for higher-order modes.
A psychoacoustic test was performed to assess the effectiveness of sound exposure level (SEL) for indicating changes in annoyance to helicopter noise. SEL was evaluated for flyover auralizations of ...optimized rotor designs and for flyover recordings of different helicopters and maneuvers. The test used paired comparisons of flyovers within 10 dB of the maximum A-weighted sound pressure level. For stimuli of equal SEL, annoyance responses showed whether or not SEL is a good indicator of annoyance. While this work does not seek to determine specific attributes contributing to annoyance that are not included in SEL, the magnitude of this offset is of primary interest. Specifically, annoyance responses to relative differences in SEL allowed the calculation of an equal annoyance point. Reductions in SEL lead to reductions in annoyance as expected, but for certain cases, SEL can fail to capture perceptually significant features such as audible differences due to changes in tail rotor design or unsteadiness in the sound of the helicopter.
Satisfactory acoustics is crucial for the ability of spaces such as auditoriums and lecture rooms to perform their primary function. The acoustics of dwellings and offices greatly affects the quality ...of our life, since we are all consciously or subconsciously aware of the sounds to which we are daily subjected. Architectural acoustics, which encompasses room and building acoustics, is the scientific field that deals with these topics and can be defined as the study of generation, propagation, and effects of sound in enclosures. Modeling techniques, as well as related acoustic theories for accurately calculating the sound field, have been the center of many major new developments. In addition, the image conveyed by a purely physical description of sound would be incomplete without regarding human perception; hence, the interrelation between objective stimuli and subjective sensations is a field of important investigations. A holistic approach in terms of research and practice is the optimum way for solving the perplexing problems which arise in the design or refurbishment of spaces, since current trends in contemporary architecture, such as transparency, openness, and preference for bare sound-reflecting surfaces are continuing pushing the very limits of functional acoustics. All the advances in architectural acoustics gathered in this Special Issue, we hope that inspire researchers and acousticians to explore new directions in this age of scientific convergence.
ABSTRACT Antimicrobial resistance (AMR) is a worldwide concern and a threat to global public health. On the other hand, Escherichia coli has played a significant role in the evolution of AMR. The ...current study aimed to characterise the spatial pattern of AMR of extra-intestinal clinical E. coli isolated from commercial poultry in western provinces of Cuba. Data for the study covered January-2014 to December-2017. Trend analysis and exploratory description were carried out using R environment 4.0.4. ArcMap 10.4 was used for the spatial analysis by the Kernel Density Estimation method and visualisation map. Incremental trends in the frequency of resistance were observed during the study period. Kernel Density indicated that AMR was spatially distributed across the whole geographical region under study, although the highest density (high values) of AMR was located mainly in municipalities of Artemisa province. Areas of significantly higher and lower risk of AMR were identified in the Southeast and North of the region, respectively. Finally, the identification of the spatial distribution and relative risk surface of E. coli antimicrobial resistance from poultry farms in Cuba is a major step that contributes to optimise antimicrobial stewardship practices across the western region. This allows for improved preventive health measures and control strategies to prevent diseases and increase epidemiological surveillance.
ABSTRACT E2-CD154 is a subunit vaccine candidate that has been proven to be safe and to protect piglets from classical swine fever (CSF). In this study, those previous findings were confirmed and ...extended to a larger number of animals in a phase III clinical trial conducted on two production farms in Pinar del Río province. All animals in both farms were vaccinated with two doses of E2-CD154 on days 0 and 21. The study extended up to 60 weeks. The vaccine was well tolerated in piglets between 15 and 28 days of life, with neither local nor systemic side effects documented. Immunized pregnant sows were capable of transmitting high levels of maternally-derived neutralizing antibodies (MDNAs) to their offspring (Unit A, geometric mean titer = 1:1295, minimum value 1:100 and Unit B geometric mean titer = 1:474, minimum value 1:150), well above the protection threshold (1:50). These high MDNA titers in the piglets did not interfere with the immunogenicity of the candidate. All vaccinated piglets evaluated at random (more than 10% of 2804 vaccinated) developed protective neutralizing antibody titers higher than 1:400 at the four time points analyzed (nine, 21, 41, and 44 weeks) in both farms. The results of this study confirm the safety, immunogenicity and robustness of this vaccine candidate in this sensitive pig category in the field.
ABSTRACT Streptococcus equi subsp. zooepidemicus (S. zooepidemicus) is an opportunistic pathogen capable of causing various infections in the respiratory, genital, and urinary tracts of horses and ...other animals. This species is considered responsible for many emerging zoonotic diseases. There has been an increasing circulation of multidrug-resistant S. zooepidemicus strains in horses, however, there is no information on S. zooepidemicus and its antimicrobial susceptibility profile in Cuban horses. Therefore, the objectives of this study were to report the isolation of S. zooepidemicus in a horse and to determine its antimicrobial susceptibility profile. A mare with pale mucous membranes, owned by a private producer in Melena del Sur, Mayabeque, was sampled, and a swab was taken from the genital tract. The isolate obtained was identified using the analytical profile index and mass spectrometry. The minimal inhibitory concentration (MIC) of 11 antibiotics (penicillin G, ampicillin, amoxicillin-clavulanate, cefquinome, imipenem, gentamicin, enrofloxacin, doxycycline, erythromycin, chloramphenicol, and vancomycin) was determined for the isolate. The isolate was identified as S. zooepidemicus and it was susceptible to all β-lactam, erythromycin, chloramphenicol, and vancomycin. The isolate presented a multidrug resistance profile to gentamicin, enrofloxacin, and doxycycline with MIC values of 16 μg/mL, 2 μg/mL, and 2 μg/mL, respectively. For the first time in Cuba, multidrug-resistant S. zooepidemicus was detected in the genital mucosa of a mare. The close interaction between humans and horses increases the risk of acquiring these multiresistant microorganisms or favoring their dissemination, thus this result should be considered in staff training.
RESUMEN La región de Tuxpan se caracteriza por una fuerte actividad petrolífera y la producción de alimentos ecológicos. Las actividades petroleras son fuente emisora de hidrocarburos aromáticos ...policíclicos (HAPs) a la atmósfera y estos contaminan los suelos y los pastos de las granjas por deposición atmosférica. El objetivo de este estudio fue determinar el contenido de hidrocarburos aromáticos policíclicos (HAPs) en leche cruda procedente de dos unidades de producción ecológica. Los análisis se realizaron mediante cromatografía de gases con detección por ionización de flama, de acuerdo con la metodología de la US EPA. Se detectó la presencia de HAPs en leche, donde la mediana de los mismos osciló entre 0.08-0.86 µg/kg de leche fresca (lf). Los compuestos fluoranteno (FLT), benzo(a)antraceno (BaA), benzo(k)fluoranteno (BkF) y benzo(a)pireno (BaP) presentaron una frecuencia de aparición por encima del 90%, existiendo un predominio de los HAPs de 4-6 anillos. No existió diferencia significativa (p<0.05) en el valor de la mediana del BaP y la suma de los 4HAPs (BaA, BaP, benzo(b)fluoranteno (BbF) y criseno (CHR)) en la leche de las dos granjas cercanas a la termoeléctrica y planta bombeadora de petróleo. El valor de la mediana del BaP se encontró por debajo de la normativa de la Unión Europea (1 µg/kg). Sin embargo, la suma de la mediana de los 4 HAPs presentaron valores de 1.58 µg/kg lf (granja A) y 1.99 µg/kg lf (granja B) por encima del valor permitido. Los resultados corroboraron que las producciones ecológicas también son susceptibles a la contaminación de HAPs. Este hallazgo alerta a los organismos reguladores la necesidad de establecer programas de monitoreos de estos contaminantes en leche orgánica con destino al consumo humano.
RESUMEN La diarrea epidémica porcina (DEP) es una enfermedad contagiosa producida por el virus del mismo nombre que es clasificado dentro del género Alphacoronavirus, familia Coronaviridae. Este ...virus produce diarrea, vómitos y pérdida de peso en cerdos de todas las edades, pero en los cerditos neonatos alcanza una morbilidad y mortalidad de hasta el 100%. En Ecuador, fue diagnosticada por primera vez en el 2014 mediante PCR convencional o en punto final. Actualmente existe la necesidad de contar con un ensayo ultrasensible, específico, que permita trabajar un gran número de muestras para facilitar la vigilancia epidemiológica de nuevos brotes y detectar animales portadores. Se desarrolló y evaluó un ensayo de PCR en tiempo real con un colorante intercalador de ADN como el SYBR Green para detectar el virus de la DEP (VDEP) en heces de cerdos, con cebadores que tienen como diana el gen N del virus. En la evaluación de la sensibilidad analítica se utilizó un patrón de ARN del VDEP sintetizado en el laboratorio, determinándose que el límite de detección del ensayo desarrollado fue de 4 copias de ARN del VDEP, comparando con la PCR en punto final que fue 100 veces más sensible, la especificidad del ensayo se basó en la posibilidad de detectar falsos positivos mediante la curva de disociación. Los valores de Ct (valor umbral) en el análisis intra e inter-ensayo mostraron coeficientes de variación válidos. En la evaluación del desempeño diagnóstico, el ensayo detectó 18 muestras positivas de un total de 52 para un 100% de concordancia con el PCR en punto final. Se concluye que el ensayo de PCR en tiempo real con SYBR Green desarrollado es altamente sensible, específico, reproducible y rápido para el diagnóstico del VDEP en homogenados de mucosa intestinal de cerdos.
RESUMEN La mastitis bovina es un desafío sanitario y económico para la producción animal, no solo porque afecta la salud y bienestar de los animales, sino también por la amenaza que representa para ...la salud pública, sin descontar las pérdidas millonarias que ocasionan los costos de tratamiento y el descarte de leche, un alimento por demás imprescindible para una población en plena expansión a nivel global. En Zamora-Chinchipe se demostró previamente Mollicutes en leche de tanque y vacas individuales. Para analizar los factores de riesgo asociados a esta problemática se aplicaron cuestionarios semi-estructurados a los rebaños previamente investigados. Las variables con p-valor<0,2 en el análisis univariado se seleccionaron e incluyeron en el modelo multivariado respectivo, que finalmente se ajustó manualmente mediante el procedimiento de eliminación hacia atrás (backward) para retirar las variables no significativas (p<0,05). Son factores de riesgo de Mollicutes en los rebaños un número mayor de categorías zootécnicas en la finca (RP=1,691; IC95%: 1,293 - 2,210), la presencia de ganado Holstein (RP=15,89; 1,44 - 175,45), fuentes de abasto de agua diferentes al acueducto (río, pozo, presa) (RP=4,37; 1,306 - 14,620) y las fincas que compran animales dentro de la misma provincia (RP=4,28; 1,416 - 12,939). En tanto, el lavado de las manos del ordeñador entre vacas o entre grupos mostró una prevalencia 57% y 67,6% menor, respectivamente, que en hatos donde esta medida no se cumple. Además, el secado de los cuartos con papel previo al ordeño (prevalencia 69,6% menor) es también un factor de protección de Mollicutes en vacas individuales.
