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At least 397 records · Page 22Linked to original sources
PubMedDate not supplied

Power spectrum analysis of spontaneous fluctuations in the photoplethysmographic signal.

Direct measurement of variability in the peripheral circulation was performed by means of photoplethysmography, which provides assessment of blood volume in tissue and systolic blood volume increase. Both parameters showed oscillations at a relatively low frequency, about 0.02 Hz, and a relatively high frequency, about 0.3 Hz, which is related to respiration. These frequencies are similar to those found in measurements of heart rate variability--which is also obtained by measuring the photoplethysmographic period variability--but the powers of the different frequencies are different. The low frequency oscillation, which is attributed to the activity of the sympathetic nervous system, is more pronounced in the measurements of tissue blood volume and of systolic blood volume increase than in the measurement of heart rate.

Adult↗
PubMed1995

1H nuclear magnetic resonance of human seminal plasma in in vitro fertilization attempts: use of automatic spectrum analysis.

Seminal plasma affects the quality of spermatozoa. The possible use of 1H nuclear magnetic resonance (NMR) analysis of human seminal plasma to determine a full biochemical profile that would allow the prediction of successful in vitro fertilization was examined. Two seminal plasma patterns (GI and GII) were found. The main compounds in GI were glycerophosphorylcholine, citrate and lactate, and in GII, choline and amino acids. These patterns did not fit into the usual spermogram classes. However, GI exhibited the higher pregnancy rate, suggesting that the equilibrium established between the components in seminal plasma affected not only the quality of spermatozoa but also embryonic quality.

Adult↗
PubMed1982

The validity of real-time spectrum analysis of Finnish vowel formants in profoundly hearing-impaired children.

A two-dimensional vowel chart has been used in the presentation of the articulatory positions of eight Finnish vowels produced by deaf subjects. The method and its evaluation is presented, showing individual analyses of a 13-year-old deaf boy. The values of the two lowest formants were determined from the real-time spectral analyses of each Finnish vowel and their positions on the vowel diagram, and these are compared with the identifications by listeners with normal hearing. Although the distortion and fuzziness of vowel spectra caused some difficulties in the exact determination of formant values, the comparison showed a fairly high validity for the method. This kind of vowel chart can be used for the estimation of individual articulatory capacity of deaf subjects.

Adolescent↗
PubMed2000

Usefulness of a developed four-channel EGG system with running spectrum analysis.

Electrogastrography (EGG) is a method of measuring action potentials on the abdomen. It is noninvasive, inexpensive and easy to measure. However, the EGG signal has a very low frequency (0.05 Hz) and an extremely low amplitude (10-100 microV). Consequently, its measured waveform is difficult to analyze and it is not yet completely understood. In this study, a four-channel EGG measurement system was built to measure the action potential of the stomach. This system was compared with the commercially available one-channel Digitrapper EGG. The 3 cpm percentages were compared between the best channel of the four-channel system and channel 1, whose electrode position was similar to the commercially available one-channel system for normal subjects. The average 3 cpm percentage of the best channel and channel 1 for preprandial measurement was 89.5% and 83.2%, respectively, and this was statistically significant (p < 0.001). Also the average 3 cpm percentage of the best channel and channel 1 for postprandial measurement was 90.4% and 76.5%, respectively, and this was statistically significant (p = 0.003). From these results, it can be concluded that a multi-channel EGG system is required for better EGG measurement.

Action Potentials↗
PubMed2003

[Glossodynia and the function of the autonomic nervous system--frequency spectrum analysis of RR intervals recorded electrocardiographically].

This study explored the relationship between the function of the autonomic nervous system (ANS) and glossodynia. The function of the ANS was examined in patients with glossodynia by frequency analysis of heart rate variability. The subjects were 50 women given the diagnosis of glossodynia and 24 healthy volunteers. The heart rate variability of these subjects was evaluated. Mean values of the high frequency power at rest were 1.323 +/- 1.484 ms2 in the group without functional disorders (NF group), 1.861 +/- 1.601 ms2 in the group with functional disorders (F group), and 3.229 +/- 2.044 ms2 in the standard group (H group). Mean values of HF/LF were 0.968 +/- 0.961 in the NF group, and 1.696 +/- 0.847 in the H group. Mean values of the high frequency power at rest were 1.032 +/- 977 ms2 in the group with CMIs in regions III and IV (III-IV group), 3.299 +/- 2.044 ms2 in the H group, and 2.314 +/- 1.883 ms2 in the group with CMIs in regions I and II (I-II group). Mean values of HF/LF were 0.965 +/- 0.744 in the III-IV group and 1.696 +/- 0.847 in the H group. The results of this study suggest that nervous tension, which was the cause of indefinite complaints in patients with glossodynia, had resulted from a pronounced reduction in activities of the parasympathetic nervous system, but not from an excessive increase in activities of the sympathetic nervous system. An assessment of the function of the ANS by means of heart rate variability seemed to be useful for comprehending the clinical conditions of glossodynia.

Adult↗
PubMed1983

Transcutaneous detection of subcritical arterial stenoses by Doppler signal spectrum analysis.

Early clinical studies showed significant data overlap when Doppler signal spectral analysis was used to differentiate normal carotid vessels from those with slight stenoses. A canine common carotid model has been used to study the ability of spectral analysis to detect subcritical stenoses, i.e., those with 20 to 50 per cent diameter reductions. Using the ratio of peak systolic frequency at the stenosis site to that proximal to the stenosis, significant differences from controls were found for all degrees of stenosis. The mean peak frequency ratio was 1.15 +/- 0.05 for 20 per cent stenoses, increasing to 1.68 +/- 0.50 for 50 per cent stenoses. The peak frequency ratios for Doppler signal spectra recorded from a site 1 cm distal to the stenosis exceeded control values only for 40 and 50 per cent stenoses; at a site 3 cm from the stenosis no spectra were significantly different from controls. Spectral analysis can be a direct, sensitive method to evaluate slight carotid arterial stenoses, but careful examination technique is necessary and Doppler signals must be taken from the stenotic site itself.

Animals↗
PubMedDate not supplied

[The use of emission spectrum analysis in the forensic medical expertise of gunshot wounds (experimental research)].

Presents the methodology of experimental shots from various guns (n = 11) by common cartridges and of emission spectral analysis (ESA) which was used to study the regularities in deposition of "gunshot metals" at the site of gunshot injuries and to detect the characteristic differences in shooting with and without obstacles. Effects of some factors on deposition of metal components of gunshot products at the site of gunshot injuries are studied: type of gun, shell (with/without coating or semicoated), presence of obstacles, distance, and order of the shot. Results of studies are presented for some guns, which may be useful in forensic medical expert evaluations by means of ESA.

Firearms↗
PubMed2000

Conventional and power spectrum analysis of the effects of zolpidem on sleep EEG in patients with chronic primary insomnia.

STUDY OBJECTIVE: The purpose of this study was 1) to assess the effect of zolpidem or a placebo on sleep in two groups of insomniac patients with a diagnosis of moderate-to-severe chronic primary insomnia and 2) to determine the effect of zolpidem on sleep structure using spectral analysis. DESIGN: A randomized, double-blind, placebo-controlled trial. SETTING: Sleep laboratory of the Department of Pharmacology and Therapeutics at the Clinics Hospital. PARTICIPANTS: 12 female outpatients with chronic primary insomnia. INTERVENTIONS: Zolpidem was given at a daily dose of 10 mg for 15 nights. RESULTS: The hypnotic drug reduced sleep latency and waking time after sleep onset, and increased total sleep time and sleep efficiency. Values corresponding to visually scored slow wave sleep (stage 3 and 4) showed no significant changes. All-night spectral analysis of the EEG revealed that power density in NREM sleep was significantly increased in the low frequency band (0.25-1.0 Hz) in the zolpidem group during the first 2-h interval. CONCLUSIONS: In agreement with previous findings obtained in patients with chronic primary insomnia, zolpidem significantly improved sleep induction and maintenance. Moreover, zolpidem increased power density in the 0.25-1.0 Hz band during short-term and intermediate-term treatment. Nevertheless, other frequency bands in the delta range showed a relative decrease which was not statistically significant.

Adult↗
PubMedDate not supplied

Infrared spectrum analysis of some flavonoids.

Infrared spectra of some flavonoids and quercetin and morin sulfonic derivatives were recorded. The spectral data of sodium salts of quercetin and morin sulfonic acids were interpreted as indicating the near position valency band of the carbonyl group in relation to its position in quercetin and morin. The distinct shift of this band in quercetin-5'-sulfonic acid (QSA) may probably be a result of the occurrence of an intramolecular proton transfer from the sulfonic -SO3H to the oxygen of -C=O group.

Flavonoids↗
PubMed2000

[Spectrum analysis of blue ball-point ink components by FTIR microsope].

The FT-IR microscope spectra of 108 kinds of blue ball-point writing inks have been analyzed in detail in this paper. According to the transmittance spectra, the composition in the ink such as the solvent, the pigment and the resin was identified. It is the base to determination of the age of ball-point writing inks nondestructively.

Handwriting↗
PubMed1992

[Spectrum analysis of the r-r interval using a PC].

Spectral analysis of r-r variability has been recently proposed as a clinical tool to assess the autonomic nervous system function. In this article we present the results obtained using an equipment and an analysis software (based on Maximum Entropy Method) developed in our laboratory. Analyzing the tachograms derived from prolonged ECG registrations of 12 young healthy subjects, 24 to 36 years old (mean 31 +/- 4), we observed the two classic components of the signal: a low frequency component (0.7 +/- 0.2 Hz) and a high frequency component (0.21 +/- 16.6 Hz). As expected, standing, a simple manoeuvre augmenting sympathetic activity, caused a stronger predominance of the low frequency component. We conclude that our method is reliable to evaluate, by means of spectral analysis, rhythmical oscillations of r-r variability.

Adult↗