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.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
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 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 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 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 El crecimiento de la población mundial demanda disponibilidad de suficientes alimentos nutritivos e inocuos, y la mastitis bovina es una enfermedad que aún causa grandes pérdidas económicas, ...además de otros riesgos a la salud de los rebaños y el público en general, pese a los avances tecnológicos y la profundización en el conocimiento de factores decisivos en su comportamiento, dependientes tanto de los hospederos, como de los patógenos involucrados y del ambiente donde su interación tiene lugar. Para profundizar en la asociación de Mollicutes, en los procesos de mastitis en Zamora-Chinchipe se investigaron 386 vacas, de 99 rebaños, de las que 126 resultaron positivas (32,6 %) mediante Reacción en Cadena de la Polimerasa (PCR), en tanto 340 (88,1 %) se constataron con mastitis subclínica mediante Prueba de California para mastitis. Aunque no se evidenció Mycoplasma bovis, otros micoplasmas también patogénicos pudieron estar presentes y complicar la recuperación de los rebaños afectados por la reconocida resistencia de estos microorganismos a la antibioterapia tradicional, entre otros peligros. La no asociación entre los resultados de los métodos de diagnóstico empleados evidenció que otros patógenos estuvieron involucrados en el mosaico etiológico de la mastitis en la provincia y reveló la necesidad de su indispensable profundización para orientar adecuadamente las estrategias de control.
RESUMEN Las infecciones ocasionadas por Staphylococcus aureus constituyen una problemática para la salud animal y humana. El objetivo de este trabajo fue determinar la concentración mínima ...inhibitoria (CMI) y la concentración mínima bactericida (CMB) de nanopartículas de plata (NpAg) obtenidas por síntesis verde con extracto de hojas de Leea coccinea sobre cepas de Staphylococcus aureus y aislados resistentes a meticilina. Se evaluaron tres lotes de NpAg de Leea coccinea sobre dos cepas S. aureus y dos aislados resistentes a meticilina, por el método de diluciones seriadas, para la determinación de CMI y CMB. Las NpAg de Leea coccinea mostraron actividad antibacteriana sobre las cepas y los aislados resistentes de S. aureus, con valores de CMI para los tres lotes que coincidieron en su mayoría en 0,03 mg/mL para todas las cepas y los aislados. En los valores de CMB en los tres lotes concordaron y se observaron diferencias entre los valores para los aislados resistentes (0,485 mg/mL) y las cepas (0,12 mg/mL). Estos resultados demuestran la actividad antibacteriana de las NpAg de Leea coccinea sobre este patógeno, destacan sus potencialidades como alternativa ante la resistencia a antibióticos y crean las bases para otros estudios con vista a una futura aplicación como antibacteriano.
RESUMEN La presente contribución tuvo como objetivo establecer las premisas para realizar la toma, conservación y envío de muestras para el diagnóstico parasitológico en aves; así como para la ...correcta interpretación de los resultados emitidos por el laboratorio. Los países tropicales reúnen las condiciones climáticas ideales para el desarrollo de los parásitos, sus formas de dispersión y hospederos intermediarios durante todo el año, por lo que las afectaciones parasitarias son muy frecuentes. Se han reportado pérdidas en la producción de carne y huevo cuando existen altas infestaciones de parásitos en las aves de producción. La base de cualquier programa de control lo constituye un acertado diagnóstico, pero a su vez, este último depende de la correcta toma y envío de muestras. Igualmente se necesita la correcta interpretación de los resultados del laboratorio por parte del personal veterinario de las granjas, de manera tal que puedan implementar las medidas efectivas para el control de las parasitosis. Esta situación se agrava al tener en cuenta el incremento acelerado de la resistencia antiparasitaria en los últimos años. Bajo estas condiciones es necesario comprender la importancia del control estratégico de parásitos y plagas, que no implica la erradicación de los mismos sino mantener pequeñas poblaciones que no ocasionen daños perceptibles en la salud y el comportamiento productivo de los animales mediante la utilización inteligente de los antiparasitarios. Estos resultados nos conducirán a obtener diagnósticos confiables, y proporciona elementos que permitirán el uso estratégico de los antiparasitarios disponibles.
