Detection of Howling Frequency Using Temporal Variations in Power Spectrum

Research on environmental sound recognition has not shown great development in comparison with that on speech and musical signals. One of the reasons is that the sound category of environmental sounds covers a broad range of acoustical natures. We classified them in order to explore suitable recognition techniques for each characteristic. We focus on impulsive sounds and their non-stationary feature within and between analytic frames. We used matching-pursuit as a framework to use wavelet analysis for extracting temporal variation of audio features inside a frame. We also investigated the validity of modeling decaying patterns of sounds using Hidden markov models. Experimental results indicate that sounds with multiple impulsive signals are recognized better by using time-frequency analyzing bases than by frequency domain analysis. Classification of sound classes with a long and clear decaying pattern improves when HMMs with multiple number of hidden states are applied. Index Terms: audio signal classification, non-speech sound recognition, environmental sound recognition, time-frequency analysis, Matching-Pursuit

Altered sympathetic and vagal modulations of the cardiovascular system in patients with pheochromocytoma: Their relations to orthostatic hypotension

The origin of very low frequency (VLF) oscillations in the power spectra of heart rate variability (HRV) is controversial with possible mechanisms involving thermoregulation and/or renin-angiotensin-aldosterone system. Recently, a major contribution from vagal influences has been suggested. The present study investigated the behaviour of VLF (0.004–0.040 Hz) components of HRV power spectra in a group of healthy male volunteers during their exposure to (1) dry, supine, immersion in thermo-neutral water for 6 h (n = 7) and (2) non-hypoxic hypobaria (breathing 40–60% oxygen at 15 000′ simulated in a decompression chamber) for 5 h (n = 15). The two manoeuvres are established to increase vagal outflow. During both the manoeuvres, all the frequency domain indices of HRV exhibited a significant increase. Increase in HRV was much more than that in the R-R interval. At 6 h of immersion, the R-R interval increased by ∼15% but the total power increased ∼fourfold. Similarly, at 5 h of exposure to hypobaria, total power increased ∼twofold with a very modest increase in an R-R of ∼9%. Increase in spectral power was appreciable even after normalization with mean R-R2. Increase in VLF during immersion was more than reported during enalaprilat blockade of angiotensin convertase enzyme. Plasma renin activity did not vary during hypobaria. There was a significant increase in pNN50, an established marker of cardiac vagal activity. Centre frequencies of the spectra and slope (β) of the relation between log(PSD) and log(frequency) did not change. Results were supportive of the notion that the parasympathetic system is pre-potent to influence slower (than respiratory) frequency components in HRV spectrum. Additionally, such an effect was without a change in the time constant of effector responses or pacemaker frequencies of VLF and LF periodicities and HRV was not a simple linear surrogate for cardiac vagal effects. An invariance of spectral exponent (β) ruled out contamination of VLF and LF spectra from fractal power as an alternate explanation.

The effects of steady state exercise on the power spectrum of heart rate variability were studied in 19 healthy subjects. Continuous ECG signals were recorded during 1) 15 min of rest in the supine state, 2) 10 min of standing, 3) 10 min of steady state exercise at 50% of maximum predicted power output on a cycle ergometer, and 4) 15 min of post-exercise recovery in the supine state. Autoregressive modeling was used to determine the power spectrum of heart rate variability. While orthostatic stress produced a significant 51% increase in the ratio of low to high frequency peak spectral power, steady state exercise caused a significant suppression of both low and high frequency components. The low frequency peak power rose to significantly high levels throughout 15 min of the post-exercise recovery period. There was a significant leftward shift in the frequency of the low frequency peak with exercise and a rightward shift during the recovery supine state. These results suggest that neuroregulatory control of heart rate plays a major role in adaptive responses to orthostatic stress and post-exercise recovery, while humoral factors are probably more important in maintaining heart rate during steady state exercise.

We present the results of our studies of the aperiodic optical flux variability for SS Cyg, an accreting binary systemwith a white dwarf. The main set of observational data presented here was obtained with the ANDOR/iXon DU-888 photometer mounted on the RTT-150 telescope, which allowed a record(for CCD photometers) time resolution up to 8 ms to be achieved. The power spectra of the source's flux variability have revealed that the aperiodic variability contains information about the inner boundary of the optically thick flow in the binary system. We show that the inner boundary of the optically thick accretion disk comes close to the white dwarf surface at the maximum of the source's bolometric light curve, i.e., at the peak of the instantaneous accretion rate onto the white dwarf, while the optically thick accretion disk is truncated at distances 8.5e9 cm ~10 R_{WD} in the low state. We suggest that the location of the inner boundary of the accretion disk in the binary can be traced by studying the parameters of the power spectra for accreting white dwarfs. In particular, this allows the mass of the accreting object to be estimated.

Effect of xenon on autonomic cardiovascular control—comparison with isoflurane and nitrous oxide

Introductory programming is challenging for many students, requiring them to engage with a deep approach to learning concepts in order to succeed. These challenges compound for online students who do not have direct face-to-face interactions with teaching staff. With the growing demand for online education, we need to examine approaches that assist in building supportive learning environments for these students. A growing body of work from other education disciplines indicates that audio feedback provides an opportunity for developing stronger relationships with students. Further studies recommend an integrated implementation of audio recording into the virtual learning environment. To evaluate audio feedback for use in programming education, we developed an integrated, cross-browser audio feedback feature into the open-source Doubtfire learning management system. Doubtfire is used to support and scale a task-oriented teaching and learning system built upon the principles of constructive alignment and has been shown to help students engage with programming concepts in campus-only units. Our findings from experimental and observational activities indicate that programming tutors can use a blended approach of audio and text feedback via the learning management system to better support student learning. The blended approach provides more nuanced feedback, conveying personality and feelings of connectedness to students, while retaining the benefits of specificity for code-specific issues.

Accumulating evidence suggests that time outdoors is protective against myopia development and that the choroid may be involved in this effect. The goal of this study was to examine the effect of 2 h of time outdoors in sunlight on retinal and choroidal thickness in adults. Twenty adults, ages 23-46 years, each participated in three experimental sessions on different days, consisting of 2 h of exposure to (1) indoor illumination (350 lux), (2) darkness (<0.1 lux) or (3) outdoor environment (6000-50,000 lux). Spectral-domain optical coherence tomography (SD-OCT) imaging was conducted at baseline, after 1 and 2 h of exposure, and after 1 and 2 h of follow-up. Choroidal, total retinal, photoreceptor outer segment + retinal pigment epithelium (RPE) and photoreceptor inner segment thicknesses were determined. At 2 h, the choroid was significantly thinner during the outdoor compared with the indoor and dark conditions (p< 0.01) but was not significantly different at follow-up. Total retinal thickness was significantly thicker during and after the outdoor compared with the indoor and dark conditions. The outer segment + RPE was significantly thinner during the outdoor compared with the indoor condition but was not significantly different at follow-up. The inner segment was significantly thicker during the outdoor compared with the indoor and dark conditions during exposure and follow-up. Spending 2 h outdoors under high-intensity sunlight resulted in an unexpected thinning of the choroid, which recovered post-exposure. Retinal thickness showed different responses to the outdoor and indoor environments and was sensitive to the duration of exposure.

Ergonomics improvement in a harsh environment using an audio feedback system

A study of the dynamic interactions between sleep EEG and heart rate variability in healthy young men.

Event alert and detection in smart cities using anomaly information from remote sensing earthquake data

The mean cloud albedo over a spatial or temporal domain depends not only on the mean cloud condensation nucleus (CCN) spectrum but also on the CCN spectrum variation. When the variation of CCN spectrum is neglected, cloud albedo calculated using the mean CCN spectrum is positively biased. The CCN spectrum variation due to either variation in size distribution or chemical composition, as well as its corresponding effect on mean cloud albedo, was investigated using data collected at Pt. Reyes, California, during the July 2005 Marine Stratus Experiment (MASE). Even when the variation in chemical composition during the entire 28‐day project is neglected, the error in mean cloud albedo is small, and the corresponding error in mean upwelling irradiance is less than 0.5 W/m2. This small and nonsystematic error over such an extended period suggests that for study of mean cloud albedo and upwelling irradiance, the CCN spectrum can be parameterized using the average particle chemical composition or particle activation diameter based on location or air mass type. In contrast, neglecting the variation in aerosol size distribution or CCN spectrum results in positive bias in mean cloud albedo. The bias increases superlinearly with the relative standard deviation of CCN concentration over the domain of interest. On the basis of the MASE data, the average bias in mean upwelling irradiance within grid cells of typical global models ranges 0.4–0.5 W/m2 when only the variation of aerosol size distribution is neglected and increases to 0.5–0.7 W/m2 when the variation of CCN spectrum is neglected. The bias in mean upwelling irradiance can potentially, albeit infrequently, reach 12 W/m2 within grid cells of typical global models if the mean cloud albedo is derived using the mean size distribution or mean CCN spectrum. This suggests accurate evaluation of mean cloud albedo requires the variation of CCN spectrum or aerosol size distribution be taken into consideration, at least for high variability of CCN concentration.

We study the jet in the hard state of the accreting black hole (BH) binary MAXI J1820+070. From the available radio-to-optical spectral and variability data, we put strong constraints on the jet parameters. We find while it is not possible to uniquely determine the jet Lorentz factor from the spectral and variability properties alone, we can estimate the jet opening angle (≈1.°5 ± 1°), the distance at which the jet starts emitting synchrotron radiation (∼3 × 1010 cm), and the magnetic field strength there (∼104 G), with relatively low uncertainty, as they depend weakly on the bulk Lorentz factor. We find the breaks in the variability power spectra from radio to submillimeter wavelength are consistent with variability damping over the timescale equal to the travel time along the jet at any Lorentz factor. This factor can still be constrained by the electron–positron pair-production rate within the jet base, which we calculate based on the observed X-ray/soft-gamma-ray spectrum, and the jet power, required to be less than the accretion power. The minimum (∼1.5) and maximum (∼4.5) Lorentz factors correspond to the dominance of pairs and ions, and the minimum and maximum jet power, respectively. We estimate the magnetic flux threading the BH and find the jet can be powered by the Blandford–Znajek mechanism in a magnetically arrested flow accretion flow. We point out the similarity of our derived formalism to that of core shifts, observed in extragalactic radio sources.

SummaryTo quantify the major environmental drivers of stream bacterial population dynamics, we modelled temporal differences in stream bacterial communities to quantify community shifts, including those relating to cyclical seasonal variation and more sporadic bloom events. We applied Illumina MiSeq 16S rRNA bacterial gene sequencing of 892 stream biofilm samples, collected monthly for 36‐months from six streams. The streams were located a maximum of 118 km apart and drained three different catchment types (forest, urban and rural land uses). We identified repeatable seasonal patterns among bacterial taxa, allowing their separation into three ecological groupings, those following linear, bloom/trough and repeated, seasonal trends. Various physicochemical parameters (light, water and air temperature, pH, dissolved oxygen, nutrients) were linked to temporal community changes. Our models indicate that bloom events and seasonal episodes modify biofilm bacterial populations, suggesting that distinct microbial taxa thrive during these events including non‐cyanobacterial community members. These models could aid in determining how temporal environmental changes affect community assembly and guide the selection of appropriate statistical models to capture future community responses to environmental change.

Geomagnetic field mapping from a satellite: Spatial power spectra of the geomagnetic field at various satellite altitudes relative to natural noise sources and instrument noise