Assessment of Arrow-of-Time Metrics for the Characterization of Underwater Explosions.

Anthropogenic impulsive sound sources with high intensity are a threat to marine life and it is crucial to keep them under control to preserve the biodiversity of marine ecosystems. Underwater explosions are one of the representatives of these impulsive sound sources, and existing detection techniques are generally based on monitoring the pressure level as well as some frequency-related features. In this paper, we propose a complementary approach to the underwater explosion detection problem through assessing the arrow of time. The arrow of time of the pressure waves coming from underwater explosions conveys information about the complex characteristics of the nonlinear physical processes taking place as a consequence of the explosion to some extent. We present a thorough review of the characterization of arrows of time in time-series, and then provide specific details regarding their applications in passive acoustic monitoring. Visibility graph-based metrics, specifically the direct horizontal visibility graph of the instantaneous phase, have the best performance when assessing the arrow of time in real explosions compared to similar acoustic events of different kinds. The proposed technique has been validated in both simulations and real underwater explosions.

New Insights into the Design and Application of a Passive Acoustic Monitoring System for the Assessment of the Good Environmental Status in Spanish Marine Waters.

Passive acoustic monitoring systems allow for non-invasive monitoring of underwater species and anthropogenic noise. One of these systems has been developed keeping in mind the need to create a user-friendly tool to obtain the ambient noise indicators, while at the same time providing a powerful tool for marine scientists and biologists to progress in studying the effect of human activities on species and ecosystems. The device is based on a low-power processor with ad-hoc electronics, ensuring that the system has efficient energy management, and that the storage capacity is large enough to allow deployments for long periods. An application is presented using data from an acoustic campaign done in 2018 at El Gorguel (Cartagena, Spain). The results show a good agreement between theoretical maps created using AIS data and the ambient noise level indicators measured in the frequency bands of 63 Hz and 125 Hz specified in the directive 11 of the EU Marine Strategy Framework Directive. Using a 2D representation, these ambient noise indicators have enabled repetitive events and daily variations in boat traffic to be identified. The ship noise registered can also be used to track ships by using the acoustic signatures of the engine propellers' noise.

Measuring predictability in ultrasonic signals: an application to scattering material characterization.

In this paper, we present a novel and completely different approach to the problem of scattering material characterization: measuring the degree of predictability of the time series. Measuring predictability can provide information of the signal strength of the deterministic component of the time series in relation to the whole time series acquired. This relationship can provide information about coherent reflections in material grains with respect to the rest of incoherent noises that typically appear in non-destructive testing using ultrasonics. This is a non-parametric technique commonly used in chaos theory that does not require making any kind of assumptions about attenuation profiles. In highly scattering media (low SNR), it has been shown theoretically that the degree of predictability allows material characterization. The experimental results obtained in this work with 32 cement probes of 4 different porosities demonstrate the ability of this technique to do classification. It has also been shown that, in this particular application, the measurement of predictability can be used as an indicator of the percentages of porosity of the test samples with great accuracy.

The pulsed to tonal strength parameter and its importance in characterizing and classifying Beluga whale sounds.

A large number of the vocalization studies on mammals are based on time-frequency analysis of the produced sounds. The patterns, which are extracted from the time-frequency representations, determine the classification in the different sound categories. However, there are situations where this pattern related recognition does not allow a precise characterization of the vocalization to be obtained. In these situations, a feasible alternative, which can help by giving the dominant component of the sound, is to measure the strength of the tonal and pulsed constituent units. In this work, the use of a ratio of pulsed to tonal strength is proposed to objectively measure the distribution of energy between these two components. This pulsed to tonal ratio (PTR) can be computed with the aid of the discrete cosine transform. It is demonstrated that the PTR can be obtained with a relatively simple expression without having to go through the time- frequency representation. This work presents examples that show how the PTR can be used to distinguish between two very similar Beluga whale sounds and how to dynamically track the power distribution between the pulsed and tonal components in non-stationary signals.

Evaluación del paciente geriátrico hospitalizado, orientado por problemas: estudio prospectivo de 71 casos / Evaluation of the geriatric patient, oriented by problems: prospective study of 71 cases

Para una aproximación real a la pluripatología y los problemas asociados del anciano, y analizar si la historia clínica convencional evalua en forma adecuada a éste paciente, se realizó un estudio prospectivo, el primero en el país, en 71 pacientes de 60 años o más, hospitalizados en el HNCH entre Enero y Marzo de 1991. Se observó que a diferencia del adulto jóven, nos enfrentamos no sólo a enfermedades, sino también a problemas asociados como: depresión 53.5 por ciento, ansiedad 50.7 por ciento, alteraciones en el sueño 81.7 por ciento, temblores 16.9 por ciento, caídas 67.6 por ciento, hipotensión ortástica (probable) 50.7 por ciento, incontinencia urinaria 42.3 por ciento, estreñimiento 32.4 por ciento, úlceras por presión 5.7 por ciento, transtornos de órganos sensoriales 83.1 por ciento. También se evidenció diferencia significativa entre lo observado por nosotros y lo registrado en la historia clínica convencional, fundamentalmente en lo concerniente a problemas asociados que generalmente no se consideran. Se plantea la necesidad de considerar estos aspectos durante la evaluación del geronto, así como de contar con una historia clínica geriátrica especialmente diseñada y orientada a enfermedades y problemas con el fin de brindar una adecuada atención al paciente geriátrico

Estudio comparativo de atención de pacientes mayores y menores de 60 años / Comparative study in patients older and younger than 60 years

Presentamos un estudio comparativo sobre la demanda de atención en los diferentes servicios de medicina: consulta externa, hopitalización, emergencia, del Hospital Nacional Cayetano Heredia (HNCH) entre la población de mayores y menores de 60 años desde 1985 a 1990. Se hospitalizaron 5823 pacientes, correspondiendo 1769 (30 por ciento) al de grupo mayores de 60 años. La frecuencia relativa de hospitalización fue 6 veces mayor en el grupo de mayores de 65 años que en el de 14-64 años. En los de mayores de 60 años, sin considerar los fallecidos, el promedio de hospitalización fue mayor. Las enfermedades cardiovasculares (20.78 por ciento) y cerebrovasculares (12.79 por ciento) fueron significativamente más frecuentes en el grupo de mayores de 60 años (p<0.05). La mortalidad en el grupo de mayores de 60 años fue de 16.6 por ciento mientras que en el de menores de 60 años de 7.4 por ciento, (p<0.05). La mortalidad en mayores de 60 años fue mayor en hombres que en las mujeres. La frecuencia relativa de atención en consulta externa en los mayores de 65 años fue 2 veces mayor en relación a la población de 14-64 años. Y la tasa de retorno a consulta externa en la población geriátrica fue significativamente mayor

Eficacia terapéutica y tolerancia del buflomedil en pacientes geriátricos / Therapeutical efficacy and tolerance to buflomedil in geriatric patients

Se evaluá la eficacia del buflomedil en 30 pacientes mayores de 60 años, portadores de insuficiencia cerebrovascular, a quienes se administró 600 mg al día del fármaco durante 180 días. Al día 90 del estudio se evidenció mejoría altamente significativa en todo el cortejo sintomático evaluado - cefalea, vértigo, astenia, acufenos, caídas, temblor, insomnio y mareos-, para el examen de coordinación y marcha y para el promedio de errores obtenidos con el test de Bender. La prueba de WAIS mostró mejoría significativa en el área de memoria de evocación y y las de Zung revelaron importante mejoría en el área de memoria de evocación y en los indicadores de depresión. No se registraron cambios en la presión arterial, pulso, peso o exámenes de laboratorio, salvo disminución en el ácido úrico sanguíneo