Walking is an everyday activity in our daily life. Because walking affects heart rate variability, in this research, for the first time, we analyzed the coupling among the alterations of the complexity of walking paths and heart rate. We benefited from the fractal theory and sample entropy to evaluate the influence of the complexity of paths on the complexity of heart rate variability (HRV) during walking. We calculated the fractal exponent and sample entropy of the R-R time series for nine participants who walked on four paths with various complexities. The findings showed a strong coupling among the alterations of fractal dimension (an indicator of complexity) of HRV and the walking paths. Besides, the result of the analysis of sample entropy also verified the obtained results from the fractal analysis. In further studies, we can analyze the coupling among the alterations of the complexities of other physiological signals and walking paths.

• Publication type
• Journal Article MeSH

Speech is controlled by axial neuromotor systems, therefore, it is highly sensitive to the effects of neurodegenerative illnesses such as Parkinson's Disease (PD). Patients suffering from PD present important alterations in speech, which are manifested in phonation, articulation, prosody, and fluency. These alterations may be evaluated using statistical methods on features obtained from glottal, spectral, cepstral, or fractal descriptions of speech. This work introduces an evaluation paradigm based on Information Theory (IT) to differentiate the effects of PD and aging on glottal amplitude distributions. The study is conducted on a database including 48 PD patients (24 males, 24 females), 48 age-matched healthy controls (HC, 24 males, 24 females), and 48 mid-age normative subjects (NS, 24 males, 24 females). It may be concluded from the study that Hierarchical Clustering (HiCl) methods produce a clear separation between the phonation of PD patients from NS subjects (accuracy of 89.6% for both male and female subsets), but the separation between PD patients and HC subjects is less efficient (accuracy of 75.0% for the male subset and 70.8% for the female subset). Conversely, using feature selection and Support Vector Machine (SVM) classification, the differentiation between PD and HC is substantially improved (accuracy of 94.8% for the male subset and 92.8% for the female subset). This improvement was mainly boosted by feature selection, at a cost of information and generalization losses. The results point to the possibility that speech deterioration may affect HC phonation with aging, reducing its difference to PD phonation.

• MeSH
• Speech Acoustics MeSH
• Diagnosis, Differential MeSH
• Phonation physiology   MeSH
• Humans MeSH
• Parkinson Disease complications   physiopathology   MeSH
• Speech Disorders etiology   physiopathology   MeSH
• Aged MeSH
• Aging physiology   MeSH
• Support Vector Machine * MeSH
• Check Tag
• Humans MeSH
• Male MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH

BACKGROUND: Education and learning are the most important goals of all universities. For this purpose, lecturers use various tools to grab the attention of students and improve their learning ability. Virtual reality refers to the subjective sensory experience of being immersed in a computer-mediated world, and has recently been implemented in learning environments. OBJECTIVE: The aim of this study was to analyze the effect of a virtual reality condition on students' learning ability and physiological state. METHODS: Students were shown 6 sets of videos (3 videos in a two-dimensional condition and 3 videos in a three-dimensional condition), and their learning ability was analyzed based on a subsequent questionnaire. In addition, we analyzed the reaction of the brain and facial muscles of the students during both the two-dimensional and three-dimensional viewing conditions and used fractal theory to investigate their attention to the videos. RESULTS: The learning ability of students was increased in the three-dimensional condition compared to that in the two-dimensional condition. In addition, analysis of physiological signals showed that students paid more attention to the three-dimensional videos. CONCLUSIONS: A virtual reality condition has a greater effect on enhancing the learning ability of students. The analytical approach of this study can be further extended to evaluate other physiological signals of subjects in a virtual reality condition.

• MeSH
• Humans MeSH
• Students MeSH
• Learning physiology   MeSH
• Virtual Reality * MeSH
• Check Tag
• Humans MeSH
• Male MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

OBJECTIVE: Nowadays proper detection of cognitive impairment has become a challenge for the scientific community. Alzheimer's Disease (AD), the most common cause of dementia, has a high prevalence that is increasing at a fast pace towards epidemic level. In the not-so-distant future this fact could have a dramatic social and economic impact. In this scenario, an early and accurate diagnosis of AD could help to decrease its effects on patients, relatives and society. Over the last decades there have been useful advances not only in classic assessment techniques, but also in novel non-invasive screening methodologies. METHODS: Among these methods, automatic analysis of speech -one of the first damaged skills in AD patients- is a natural and useful low cost tool for diagnosis. RESULTS: In this paper a non-linear multi-task approach based on automatic speech analysis is presented. Three tasks with different language complexity levels are analyzed, and promising results that encourage a deeper assessment are obtained. Automatic classification was carried out by using classic Multilayer Perceptron (MLP) and Deep Learning by means of Convolutional Neural Networks (CNN) (biologically- inspired variants of MLPs) over the tasks with classic linear features, perceptual features, Castiglioni fractal dimension and Multiscale Permutation Entropy. CONCLUSION: Finally, the most relevant features are selected by means of the non-parametric Mann- Whitney U-test.

• MeSH
• Alzheimer Disease diagnosis   MeSH
• Early Diagnosis MeSH
• Deep Learning MeSH
• Diagnosis, Computer-Assisted * methods   MeSH
• Adult MeSH
• Cognitive Dysfunction diagnosis   MeSH
• Cohort Studies MeSH
• Middle Aged MeSH
• Humans MeSH
• Speech Production Measurement MeSH
• Nonlinear Dynamics MeSH
• Neuropsychological Tests MeSH
• Speech * MeSH
• Pattern Recognition, Automated * methods   MeSH
• Aged MeSH
• Speech Recognition Software MeSH
• Check Tag
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Male MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

BACKGROUND: The likelihood of a Randall's plug composed of calcium oxalate monohydrate (COM) forming by the free particle mechanism in a model of kidney with a structure recently described by Robertson was examined at the most favourable conditions for the considered mechanism. METHODS: The Robertson model of the kidney is used in the following development. The classical theory of crystallization was used for calculations. RESULTS: Initial COM nuclei were assumed to form at the beginning of the ascending loop of Henle where the supersaturation with respect to COM has been shown to reach the threshold level for spontaneous nucleation. Nucleation proceeds by a heterogeneous mechanism. The formed particles are transported in the nephron by a laminar flow of liquid with a parabolic velocity profile. Particles travel with a velocity dependent on their position in the cross-section of the nephron assumed to be straight tubule with smooth walls and without any sharp bends and kinks. These particles move faster with time as they grow as a result of being surrounded by the supersaturated liquid. Individual COM particles (crystals) can reach maximum diameter of 5.2 × 10-6 m, i.e. 5.2 μm, at the opening of the CD and would thus always be washed out of the CD into the calyx regardless of the orientation of the CD. Agglomeration of COM crystals forms a fractal object with an apparent density lower than the density of solid COM. The agglomerate that can block the beginning of the CD is composed of more crystals than are available even during crystaluria. Moreover the settling velocity of agglomerate blocking the opening of the CD is lower than the liquid flow and thus such agglomerate would be washed out even from upward-draining CD. CONCLUSIONS: The free particle mechanism may be responsible for the formation of a Randall's plug composed by COM only in specific infrequent cases such as an abnormal structure of kidney. Majority of incidences of Randall's plug development by COM are caused by mechanism different from the free particle mechanism.

• MeSH
• Models, Biological * MeSH
• Chemical Phenomena MeSH
• Kidney Calculi * chemistry   etiology   MeSH
• Humans MeSH
• Kidney Tubules, Collecting * MeSH
• Calcium Oxalate analysis   chemistry   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH

• MeSH
• Delivery of Health Care MeSH
• Research MeSH
• Health MeSH
• Population Health MeSH
• Publication type
• Handbook MeSH

• Conspectus
• Veřejné zdraví a hygiena
• NML Fields
• veřejné zdravotnictví
• NML Publication type
• kolektivní monografie

Measures from the theory of nonlinear dynamics were applied on complex fractionated atrial electrograms (CFAEs) in order to characterize their physiological dynamic behavior. The results were obtained considering 113 short term atrial electrograms (A-EGMs) which were annotated by three experts into four classes of fractionation according to A-EGMs signal regularity. The following measures were applied on A-EGM signals: General Correlation Dimension, Approximate Entropy, Detrended Fluctuation Analysis, Lempel-Ziv Complexity, and Katz-Sevcik, Variance and Box Counting Fractal Dimension. Assessment of disorganization was evaluated by a Kruskal Wallis statistical test. Except Detrended Fluctuation Analysis and Variance Fractal Dimension, the CFAE disorganization was found statistically significant even for low significant level alpha = 0.001. Moreover, the increasing complexity of A-EGM signals was reflected by higher values of General Correlation Dimension of order 1 and Approximate Entropy.

• MeSH
• Algorithms MeSH
• Analysis of Variance MeSH
• Automation methods   MeSH
• Electrocardiography methods   MeSH
• Entropy MeSH
• Atrial Fibrillation physiopathology   MeSH
• Fractals MeSH
• Humans MeSH
• Heart Atria physiopathology   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

Tento článek popisuje vybrané problémy v oblasti elektroencefalografi e, současné přístupy k jejich řešení a trendy vývoje a výzkumu. Stručně jsou popsány metody počítačové klasifi kace EEG záznamů a eliminace artefaktů v nich. Dále následuje několik pokročilejších metod zpracování a praktického využití EEG, mezi něž patří teorie chaosu, analýza nezávislých komponent, skryté Markovovy modely, rozhraní mozek-počítač a EEG biofeedback. Na závěr je krátce pojednáno o přenosných EEG systémech malých rozměrů.

This paper describes selected problems in the area of electroencephalography, current approaches to their solution and trends in research and development. Methods of computer-assisted classifi cation and artifacts removing from EEG signals are briefl y mentioned. Th is paper also introduce several advanced methods of computer processing and practical use of EEG, namely Chaos theory, Independent Component Analysis, Hidden Markov models, Brain computer interface and EEG biofeedback. Small portable EEG systems are introduced at the end of paper.

• MeSH
• Monitoring, Ambulatory methods   instrumentation   utilization   MeSH
• Principal Component Analysis MeSH
• Biomedical Technology instrumentation   trends   MeSH
• Time Factors MeSH
• Electroencephalography instrumentation   trends   utilization   MeSH
• Financing, Organized MeSH
• Fractals MeSH
• Humans MeSH
• Nonlinear Dynamics MeSH
• Signal Processing, Computer-Assisted instrumentation   MeSH
• Telemetry methods   instrumentation   utilization   MeSH
• User-Computer Interface MeSH
• Feedback MeSH
• Check Tag
• Humans MeSH

• MeSH
• Algorithms MeSH
• Biomedical Engineering methods   education   MeSH
• Fractals MeSH
• Curriculum trends   MeSH
• Medical Informatics methods   trends   MeSH
• Humans MeSH
• Nonlinear Dynamics MeSH
• Universities organization & administration   trends   MeSH
• Education, Professional methods   trends   MeSH
• Check Tag
• Humans MeSH

• MeSH
• Mathematics MeSH

• Conspectus
• Přírodní vědy. Matematické vědy
• NML Fields
• přírodní vědy