Distribution of metals and radionuclides in the lichens Cladonia rangiferina and C. mitis from the past uranium mining region of Elliot Lake, Ontario, Canada.

The present study was performed in the Elliot Lake area (Ontario, Canada), a site of uranium mining and milling for nearly 40 years between 1950's and 1990's. Although mining activities ceased in the mid-1990's, the site hosts several tailings management areas (TMAs) which are under ongoing rehabilitation and monitoring. Several surveys using lichens as a biomonitoring tool were completed in the 1980s and the 1990s to assess the levels of contaminants. The present survey aimed to re-visit the historical surveys, and to determine the current status of environmental recovery of the area. Our survey consisted of sampling two lichen species, Cladonia rangiferina and C. mitis, in an area covering up to 50 km from the former mining operation and the TMAs. The results reported in this work indicated that the levels of metals and radionuclides, diagnostic of mining operations, have decreased over time: particularly, the U, Th and Pb levels in both lichen species dropped by about two orders of magnitude by the 2020's compared to the 1980's. Likewise, the Cs-137 levels in both lichen species reflect present day global background. The study provides a new set of present-day regional baseline elemental concentrations for other metals that are associated with mining (Cd, As, Ti, Cs). Finally, there were weak but statistically significant differences in the levels of some elements (U, Th, Cd) between the two lichens, suggesting these two species might have different capture mechanisms or retention abilities.

Forced expirations in normal subjects. Is the shape of the flow rate curve related to existence of a wheeze?

The flow rate curve takes different shapes during forced expirations performed by normal subjects. In some cases a wheeze may exist. In this study, we examine the conditions for appearance of a wheeze, before and after the peak flow, and the relationship between the wheeze and the shape of the flow rate curve. We analyzed ten parameters in 83 forced expirations produced by 32 normal subjects (16 men and 16 women) using multidimensional scaling techniques. Among these expirations, 53 presented a wheeze. The first two axes of the analysis define a plane on which forced expirations are divided into four quadrants. Two opposite quadrants (upper right and bottom left) contain the wheezing expirations, while the two others only have the ones with no wheezing. This distribution corresponds to specific shapes of the flow rate curve. We found that wheezes are associated with two main shapes. One of them consists of a short onset until a sharp peak, followed by a fast exponential decay. The other is about triangular, with a late appearance of the wheeze, and is only produced by women.

Acute stress disrupts risk assessment behavior in mice.

The effects of stress on risk assessment behavior in mice were studied by examining latency to emerge from a safe compartment into a large, well-lit open field. In the first experiment different groups of mice were exposed for 1 h to tube restraint, fixed interval 2-min foot shock, or attack by an aggressive conspecific. Nonstressed controls were left undisturbed in the home cage. Thirty minutes following stress animals were placed in the safe compartment and latency to emerge was recorded. Results showed all of the stressed groups exhibited significantly faster emergence latencies than nonstressed controls. In the second experiment the duration of this effect was examined by testing different groups at varying intervals following tube restraint stress. Results showed that mice tested 0.5 and 1 h following stress exhibited short entry latencies and reduced head poke responses. Performance had returned to nonstress levels 3 h after stress. These data suggest that stress reduces caution by disrupting risk assessment behaviors.

Interaction between tracheal sound and flow rate: a comparison of some different flow evaluations from lung sounds.

We simultaneously recorded tracheal sound and air flow from nine normal subjects (seven males and two females). Sound was picked up at the supra sternal notch with an air-coupled sensitive microphone held in a small airtight probe. Flow was measured at the mouth using a pneumotachograph Fleisch n degrees 2. Both sound and flow were directly digitized at a sampling rate of 5120 Hz and then divided in 128-sample blocks. For each sound block the frequency spectrum was computed using the fast Fourier transform. In order to evaluate instantaneous flow-rate from tracheal sounds we investigated eight methods divided in two groups of four. In the first group (i.e., reference curves methods), we assumed that a relationship existed between sound and flow and was thus reflected by the variations of certain parameters. We chose to use simple straightforward relationships, already known and published. We tested four different parameters. During a calibration phase, we built for each parameter P a reference curve representing the variations of P versus flow and being specific to each subject. Then, an unknown flow was evaluated in calculating P on a 128-sample block, and the reference curve gave the corresponding flow. In the second group, we made a hierarchial clustering analysis of sound spectra for revealing the frequency modifications, induced by the flow. We tested two kinds of spectra as well as two ways of associating a flow to a given cluster. This led us to four other methods for calculating the flow. All the eight methods but one gave a mean uncertainty in the measure of flow of about 15%.(ABSTRACT TRUNCATED AT 250 WORDS)

Wheezing Lung Sounds Analysis with adaptive local trigonometric transform.

Wheezes are abnormal sounds which are known to be relevant to Chronic Obstructive Pulmonary Diseases (COPD). The analysis of such signals is especially useful in patient monitoring or pharmacology. Respiratory sounds are dependent on the flow and the volume. Furthermore, they can be the result of a complex mixture of events. The analysis of lung sounds can be greatly improved with time-frequency techniques because these methods highlight the evolution of the spectra of events. In this paper, we present the application of the Adaptive Local Trigonometric Decomposition (ALTD) to lung sound analysis. This analysis provides an optimal representation of the signal in the time-frequency domain with a lattice which is adapted in time. In our work, the parameterization of the ALTD is studied for the detection of wheezing phenomena.

Time-scale segmentation of respiratory sounds.

Respiratory sounds are composed of various events: normal and so-called adventitious sounds. These phenomena present a wide range of characteristics which make difficult their analysis with a single technique. Adapted time-frequency and time-scale techniques allow to fit best, under constraints, the accuracy of analysis of a time segmentation and, by the way, make feasible the study of complex signals. We present here new approaches based only on the wavelet packet decomposition to segment respiratory sounds.

[Spectral study of laryngotracheal sounds. Methodological approach and perspectives]. / Etude spectrale des bruits laryngo-trachéaux. Approche méthodologique et perspectives.

Prior studies have shown that laryngotracheal sounds are vectors of objective information which indicate the origins and mechanisms of sound production. The first objective of this study is to confirm these earlier findings on a larger scale. The second objective is to develop a simple apparatus which permits the rapid acquisition and analysis of information for a prompt diagnosis. This study will be carried out in infants referred to the Department of otolaryngology of the Kremblin-Bicêtre Hospital over the next two years. The material and methods used are described.

[Measurement of the frequency response of several stethoscopes in common use. Consequences for cardiac and pulmonary auscultation]. / Mesure de la réponse en fréquence de quelques stéthoscopes usuels. Conséquences pour l'auscultation cardiaque et pulmonaire.

We measured the frequency response of eight stethoscope membranes and of thirteen types of stethoscopes. Measurements were made in an anechoic chamber calculating the ratio between the intensity of a sinusoidal sound coming from a loud speaker and the intensity of the transmitted sound through the membrane of the stethoscope. Small membranes have a bandwidth (without attenuation or amplification) between 10 and 600 Hz while large membranes have a bandwidth twice the size (10-1200 Hz). This good result does not appear in the case of stethoscopes showing increasing attenuation versus frequency, with a mean value from -2.5 to -10.5 dB and variations of 10 dB in the range 50-1200 Hz which is the useful bandwidth for cardiac and pulmonary auscultation. By contrast, fidelity of the measured stethoscopes was good. Discussion of the results suggests modification of stethoscope design to eliminate faults of sound transmission and to elaborate a microphone sensor allowing an electric transmission.

[Method for the evaluation of flow rate from pulmonary sounds]. / Une méthode d'évaluation du débit à partir des sons pulmonaires.

We recorded the lung sound and flow rate from six normal subjects (3 male and 3 female). Sound was picked up at the trachea with a sensitive microphone held in a small probe. Flow rate was measured at the mouth using a Fleisch No. 3 pneumotachograph. Subjects were made to breath for 15 s, with an increasing peak flow rate starting from apnoea to around 2 l.s-1. Both sound and flow rate were directly digitized (i.e. without temporary analogic recording) at a sampling rate of 5120 Hz. Sound and flow were then divided in 128-sample blocks. For each block, the frequency spectrum was computed using the fast Fourier transform. Frequency spectrum depends on the flow rate in many ways. We computed the following formula on each spectrum: D = K.Fmean/(1 + A/Amean) where K and A are constant, Fmean and Amean are respectively the mean frequency and the mean amplitude of the spectrum computed on a 128-sample block. D may be considered as an evaluation of the flow rate every 50 ms. Plotted versus the measured values of the flow rate, D showed a linear relationship. This feature can be used as an almost instantaneous evaluation of the flow rate, or it is possible to compute the mean of D over consecutive 128-sample blocks. This has lead us to calculate the mean of the flow rate over 100, 200, ..., 800 ms. Of course, the longer the time window, the better the correlation between computed flow and real value. The values obtained for this correlation varied between 0.79 and 0.94.

[Differences between right and left ears for pitch perception]. / Différences entre oreille droite et oreille gauche pour la perception de la hauteur des sons

We define here tonal melodies and spectral melodies: For sounds containing only octaves, the former correspond to fundamental frequency variations and the latter to spectral envelope variations. In this paper we give statistical results of judgements showing that tonal melodies are better perceived by the right ear. Conversely the left ear is more able to recognize spectral melodies.

An accurate recording system and its use in breath sounds spectral analysis.

An accurate recording system was set up and used for analyzing normal and asthmatic breath-sound features. Breath sounds are recorded at the trachea simultaneously with the airflow signal at 0.5- and 1-1/s levels. The study was carried out in the frequency domain using a fast-fourier transform (FFT). FFTs are taken on 1,024-sample blocks (one block = 200 ms) over a duration of about 20 s. Different characteristics of the spectra are calculated in the range 60-1,260 Hz for 11 normal and 10 asthmatic subjects. This allows the computation of an index that discriminates (P less than 0.0005) asthma cases from normal cases. Spectral features strongly depend on the flow rate both for normal and asthmatic subjects. Increasing the flow rate raises the high-frequency components of the spectra.

Wheezes.

Wheezes are continuous adventitious lung sounds. The American Thoracic Society Committee on pulmonary nomenclature define wheezes as high-pitched continuous sounds with a dominant frequency of 400 Hz or more. Rhonchi are characterized as low-pitched continuous sounds with a dominant frequency of about 200 Hz or less. The large variability in the predominant frequency of wheezes is one of the difficulties encountered with automated analysis and quantification of wheezes. The large variations observed in automated wheeze characterization emphasize the need for standardization of breath sound analysis. This standardization would help determine diagnostic criteria for wheeze identification. The mechanism of wheeze production was first compared to a toy trumpet whose sound is produced by a vibrating reed. The pitch of the wheeze is dependent on the mass and elasticity of the airway walls and on the flow velocity. More recently, a model of wheeze production based on the mathematical analysis of the stability of airflow through a collapsible tube has been proposed. According to this model, wheezes are produced by the fluttering of the airways walls and fluid together, induced by a critical airflow velocity. Many circumstances are suitable for the production of continuous adventitious lung sounds. Thus, wheezes can be heard in several diseases, not only asthma. Wheezes are usual clinical signs in patients with obstructive airway diseases and particularly during acute episodes of asthma. A relationship between the degree of bronchial obstruction and the presence and characteristics of wheezes has been demonstrated in several studies. The best result is observed when the degree of bronchial obstruction is compared to the proportion of the respiratory cycle occupied by wheeze (tw/ttot). However, the relationship is too scattered to predict forced expiratory volume in one second (FEV1) from wheeze duration. There is no relationship between the intensity or the pitch of wheezes and the pulmonary function. The presence or quantification of wheezes have also been evaluated for the assessment of bronchial hyperresponsiveness. Wheeze detection cannot fully replace spirometry during bronchial provocation testing but may add some interesting information. Continuous monitoring of wheezes might be a useful tool for evaluation of nocturnal asthma and its treatment.