Search results for " REM"
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Neural net classification of REM sleep based on spectral measures as compared to nonlinear measures
2001
In various studies the implementation of nonlinear and nonconventional measures has significantly improved EEG (electroencephalogram) analyses as compared to using conventional parameters alone. A neural network algorithm well approved in our laboratory for the automatic recognition of rapid eye movement (REM) sleep was investigated in this regard. Originally based on a broad range of spectral power inputs, we additionally supplied the nonlinear measures of the largest Lyapunov exponent and correlation dimension as well as the nonconventional stochastic measures of spectral entropy and entropy of amplitudes. No improvement in the detection of REM sleep could be achieved by the inclusion of …
The dimensionality of human's electroencephalogram during sleep.
1991
In order to perform an analysis of nonlinear EEG-dynamics we investigated the EEG of ten male probands during sleep. According to Rechtschaffen and Kales (1968) we scored the sleep-EEG and applied an algorithm, proposed by Grassberger and Proccaccia (1983) to compute the correlation dimension of different sleep stages. The correlation dimension characterizes the dynamics of the EEG signal and estimates the degrees of freedom of the signal under study. We could demonstrate, that the EEG of slow wave sleep stages depicts a dimensionality, which is two units smaller than that of light or REM sleep.
A Nonlinear Approach to Brain Function: Deterministic Chaos and Sleep EEG
1992
In order to perform a nonlinear dimensional analysis of the sleep electroencephalogram (EEG), we applied an algorithm proposed by Grassberger and Procaccia to calculate the correlation dimension D2 of different sleep stages under Lorazepam medication versus placebo. This correlation dimension characterizes the dynamics of the sleep EEG and it estimates the degrees of freedom of the signal under study. We demonstrate that slow-wave sleep depicts a much smaller dimensionality than light or rapid eye movement (REM) sleep, and that Lorazepam does not alter the EEG's dimensionality except in stage II and REM.
Human sleep under the influence of pulsed radiofrequency electromagnetic fields: A polysomnographic study using standardized conditions
1998
To investigate the influence of radiofrequency electromagnetic fields (EMFs) of cellular phone GSM signals on human sleep electroencephalographic (EEG) pattern, all-night polysomnographies of 24 healthy male subjects were recorded, both with and without exposure to a circular polarized EMF (900 MHz, pulsed with a frequency of 217 Hz, pulse width 577 μs, power flux density 0.2 W/m2. Suppression of rapid eye movement (REM) sleep as well as a sleep-inducing effect under field exposure did not reach statistical significance, so that previous results indicating alterations of these sleep parameters could not be replicated. Spectral power analysis also did not reveal any alterations of the EEG rh…
Effects of Pulsed High-Frequency Electromagnetic Fields on Human Sleep
1996
In the present study we investigated the influence of pulsed high-frequency electromagnetic fields of digital mobile radio telephones on sleep in healthy humans. Besides a hypnotic effect with shortening of sleep onset latency, a REM suppressive effect with reduction of duration and percentage of REM sleep was found. Moreover, spectral analysis revealed qualitative alterations of the EEG signal during REM sleep with an increased spectral power density. Knowing the relevance of REM sleep for adequate information processing in the brain, especially concerning mnestic functions and learning processes, the results emphasize the necessity to carry out further investigations on the interaction of…
The quality of plasma collected by automated apheresis and of recovered plasma from leukodepleted whole blood.
2005
Background There exists a current lack of information about the composition of the different types of plasma. No direct comparisons between apheresis plasma (AP) and recovered plasma (RP) derived from in-line-filtered whole blood (WB) have been published to date. Study design and methods Sixty AP units, 100 RP units from in-line-filtered WB held for 3 hours at 20 degrees C between donation and freezing, and an additional 100 RP units held for 15 hours at 20 degrees C before freezing were analyzed for coagulation factors and inhibitors, total protein, immunoglobulin G (IgG), and hemostasis and proteolysis activation markers. The influence of twice freezing and thawing on clotting factors V, …
Double-decision lexical tasks in thought-disordered schizophrenic patients: a path towards cognitive remediation?
2005
Abstract It has been shown that schizophrenics have certain difficulties in the processing of semantic context. These difficulties have usually been evaluated using lexical decision tasks with semantic priming. In this study, we chose to examine the idea of an abnormality in the early stages of semantic context processing in thought-disordered schizophrenics using two double lexical decision tasks: one with a high (25%) and one with a low (15%) proportion of related words to assess the participants’ competency in controlled and possibly also more automatic context processing. The results obtained in 40 control participants and 40 schizophrenic patients revealed no significant differences in…
Ectopic third molar in the mandibular condyle: A review of the literature
2012
Objectives: To evaluate the etiopathogenesis, clinical features, therapeutic options, and surgical approaches for removal of ectopic third molars in the mandibular condyle. Study design: MEDLINE search of articles published on ectopic third molars in the mandibular condyle from 1980 to 2011. 14 well-documented clinical cases from the literature were evaluated together with a new clinical case provided by the authors, representing a sample of 15 patients. Results: We found a mean age at diagnosis of 48.6 years and a higher prevalence in women. In 14 patients, associated radiolucent lesions were diagnosed on radiographic studies and confirmed histopathologically as odontogenic cysts. Clinical…
Evaluation of Kharma scale as a predictor of lower third molar extraction difficulty
2017
Background The Evaluation of the degree of lower third molar (L3M) extraction difficulty is extremely important for both clinicians and patients. This study aimed to evaluate the validity of a new index (Kharma scale) as a preoperative predictor index of the difficulty of surgical removal of impacted L3M. Material and Methods Extraction difficulty of a series of 49-impacted L3M was predicted preoperatively by Kharma scale, and postoperative difficulty was assessed with a modified Parant scale. Results The sensitivity of Kharma scale, as a predictor of difficulty, was 18.2% and the specificity was 68.4%. Likelihood ratios for the Kharma categories also indicated that the scale is of little v…
Endonasal Approach for Nasal and Paranasal Sinus Tumor Removal
2001
Patients with benign (53) and malignant (22) tumors of the nose and paranasal sinuses were treated for tumor removal via an endonasal approach. Patient selection was based on tumor location (centrally) rather than histology. Tumors attainable by the endonasal approach were located in the nasal cavity, the ethmoid sinus, the sphenoid sinus and the medial wall of the maxillary sinus. Endonasal microscopic techniques including endonasal orbital decompression and endonasal closure of CSF-leaks were combined with surgical navigation tools in selected cases. Surgical trauma and morbidity could be minimized without compromising radicality of tumor removal. Postoperative hospitalization was compara…