Sound emission of solid surfaces through bubble layer

The analysis of the influence of a thin homogeneous bubble layer on sound emission from a solid surface is carried out. Sound pulses and monochromatic wave packets with a carrier frequency equal to the resonant frequency of the bubbles forming the bubble layer are considered. It is shown that the bubble layer transforms short sound pulses into wave sound packets and significantly reduces the amplitude of the emitted sound. The structure of a sinusoidal wave packet is transformed similarly. A long sound pulse is stored in the form of a pulse, its shape changes significantly. A homogeneous bubble layer near a solid radiating surface is an open resonator. The layer generates far-field radiation with spectral lines depending on the method of layer excitation and the internal properties of the bubble layer. The resonant frequency of the bubble is the limiting frequency in the spectrum, but it is not distinguished by a separate line.

Deep learning-based robust automatic non-invasive measurement of blood pressure using Korotkoff sounds

This paper proposes a method that automatically measures non-invasive blood pressure (BP) based on an auscultatory approach using Korotkoff sounds (K-sounds). There have been methods utilizing K-sounds that were more accurate in general than those using cuff pressure signals only under well-controlled environments, but most were vulnerable to the measurement conditions and to external noise because blood pressure is simply determined based on threshold values in the sound signal. The proposed method enables robust and precise BP measurements by evaluating the probability that each sound pulse is an audible K-sound based on a deep learning using a convolutional neural network (CNN). Instead of classifying sound pulses into two categories, audible K-sounds and others, the proposed CNN model outputs probability values. These values in a Korotkoff cycle are arranged in time order, and the blood pressure is determined. The proposed method was tested with a dataset acquired in practice that occasionally contains considerable noise, which can degrade the performance of the threshold-based methods. The results demonstrate that the proposed method outperforms a previously reported CNN-based classification method using K-sounds. With larger amounts of various types of data, the proposed method can potentially achieve more precise and robust results.

Can PIES (Pressure Inverted Echo Sounders) replace tall moorings to monitor the AMOC?

<p>Pressure Inverted Echo Sounders, sited on the seabed, indirectly measure the density of the water above them by combining pressure and travel time of an echo-sound pulse to the surface. Where the approximate structure of the water column is locally known, they can be used to select between a number of typical TS profiles (a gravest empirical mode or GEM field), providing temperature and salinity. But how accurate is this profile, and can such an instrument replace the expensive tall moorings currently used to monitor the MOC? We evaluate PIES deployments at 26N on the western boundary of the Atlantic between 2006 and 2018. We find that high-frequency (around weekly) variations in temperature are well captured by this technique, and the geostrophic part of the AMOC could be estimated in this way. However the GEM databases don't account for all low frequency variations in temperature and salinity profiles. At 26N we see for example, the results from PIES with cold bias above the thermocline and with a compensatory warm bias below it, and these biases lasting months or years. The profiles are also inaccurate at the surface, although seasonally-varying GEM fields may be helpful here. However the technique shows promise, and if it is developed further incorporating additional data sources such ARGO or as sea-surface temperature it may be possible to use it for long term monitoring of the Atlantic at 26N.</p>

APPLICATION OF INSTRUMENTAL METHODS IN TRUNKS ASSESSMENT OF PINUS SYLVESTRIS L.

Assessment of stem wood quality in urban environment is relevant due to the fact that trees felled under increased wind load cause enormous damage to the city economy and lead to human losses. The aim of the study was to assess the viability of growing Scotch pine (Pinus sylvestris L.) trees using pulsed tomography and drilling resistance measurements. Research in coniferous forest plots included the development during the construction of the city. Arbotom® equipment of the German company RINNTECH was used to study the trunk by pulsed tomography. Drilling method was used (Resistograph® 4450 device) to estimate the relative density of the stem wood. A total of 20 model trees were examined: 10 trees each on 2 test plots. An instrumental-visual description was compiled for each tree: height and diameter, girth of the trunk at the root neck and at breast height, the shape and length of the crown, the shape of the trunk, the presence of visible defects in the trunk were visually determined. It was found that the average speed of sound pulse in the wood of the studied model trees fluctuates in the range of 1003-1349 m/s. The research based on the data of instrumental study of the quality of stem wood (Scots pine) at the age of 60-70 under the conditions of intense exposure to industrial emissions and recreational load. Zones of local wood destruction have been clearly defined in the structure of the density distribution. Comparison of the results (obtained by two different assessment methods of wood state at the same object) shows high degree of comparability. The parallel use of two measuring instruments in assessing the growing tree state increases the accuracy of the obtained data and enables more reliable determination of emergency trees, areas of their maximum destruction and, as a consequence, the most probable direction of tree fall.

A new method of recording from the giant fiber of Drosophila melanogaster shows that the strength of its auditory inputs remains constant with age

There have been relatively few studies of how central synapses age in adult Drosophila melanogaster. In this study we investigate the aging of the synaptic inputs to the Giant Fiber (GF) from the Johnston’s Organ neurons (JONs). In previously published experiments an indirect assay of this synaptic connection was used; here we describe a new, more direct assay, which allows reliable detection of the GF action potential in the neck connective, and long term recording of its responses to sound. Genetic ablation using diphtheria toxin expressed in the GF with R68A06-GAL4 was used to show that these signals indeed arose from the GF and not from other descending neurons. As before, the sound-evoked action potentials (SEPs) in the antennal nerve were recorded via an electrode inserted at the base of the antenna. We then used this technique to quantify the response of the JONs to a high frequency sound pulse, and also the strength of the JON-GF synapse, in males and female of different ages. At no age was there any significant difference between males and females, for any of the parameters measured. Sensitivity of the JONs increased between 1 d and 10 d, with the sound intensity that elicited a half-maximal SEP decreasing by 40%. This measure almost doubled by 20 d and had increased 3-fold by 50 d compared to 10 d. Thus, JONs are most responsive around the period when most matings are taking place. The strength of the JON-GF synaptic connection itself was quite variable and did not change significantly with age. As a result, the GF’s sensitivity to sound approximately followed the JONs’ sensitivity, but with greater variability.