Cardiorespiratory Phase-Coupling Is Reduced in Patients with Obstructive Sleep Apnea

Cardiac and respiratory rhythms reveal transient phases of phase-locking which were proposed to be an important aspect of cardiorespiratory interaction. The aim of this study was to quantify cardio-respiratory phase-locking in obstructive sleep apnea (OSA). We investigated overnight polysomnography data of 248 subjects with suspected OSA. Cardiorespiratory phase-coupling was computed from the R-R intervals of body surface ECG and respiratory rate, calculated from abdominal and thoracic sensors, using Hilbert transform. A significant reduction in phase-coupling was observed in patients with severe OSA compared to patients with no or mild OSA. Cardiorespiratory phase-coupling was also associated with sleep stages and was significantly reduced during rapid-eye-movement (REM) sleep compared to slow-wave (SW) sleep. There was, however, no effect of age and BMI on phase coupling. Our study suggests that the assessment of cardiorespiratory phase coupling may be used as an ECG based screening tool for determining the severity of OSA

A quantitative comparison of different methods to detect cardiorespiratory coordination during night-time sleep

BACKGROUND: The univariate approaches used to analyze heart rate variability have recently been extended by several bivariate approaches with respect to cardiorespiratory coordination. Some approaches are explicitly based on mathematical models which investigate the synchronization between weakly coupled complex systems. Others use an heuristic approach, i.e. characteristic features of both time series, to develop appropriate bivariate methods. OBJECTIVE: In this study six different methods used to analyze cardiorespiratory coordination have been quantitatively compared with respect to their performance (no. of sequences with cardiorespiratory coordination, no. of heart beats coordinated with respiration). Five of these approaches have been suggested in the recent literature whereas one method originates from older studies. RESULTS: The methods were applied to the simultaneous recordings of an electrocardiogram and a respiratory trace of 20 healthy subjects during night-time sleep from 0:00 to 6:00. The best temporal resolution and the highest number of coordinated heart beats were obtained with the analysis of 'Phase Recurrences'. Apart from the oldest method, all methods showed similar qualitative results although the quantities varied between the different approaches. In contrast, the oldest method detected considerably fewer coordinated heart beats since it only used part of the maximum amount of information available in each recording. CONCLUSIONS: The method of 'Phase Recurrences' should be the method of choice for the detection of cardiorespiratory coordination since it offers the best temporal resolution and the highest number of coordinated sequences and heart beats. Excluding the oldest method, the results of the heuristic approaches may also be interpreted in terms of the mathematical models

The right delay: Detecting specific spike patterns with STDP and axonal conduction delays

Item does not contain fulltextAxonal conduction delays should not be ignored in simulations of spiking neural networks. Here it is shown that by using axonal conduction delays, neurons can display sensitivity to a specific spatio-temporal spike pattern. By using delays that complement the firing times in a pattern, spikes can arrive simultaneously at an output neuron, giving it a high chance of firing in response to that pattern. An unsupervised learning mechanism called spike-timing-dependent plasticity then increases the weights for connections used in the pattern, and decreases the others. This allows for an attunement of output neurons to specific activity patterns, based on temporal aspects of axonal conductivity.ICANNGA 10 - 10th international conference, ICANNGA 2010, Ljubljana, Slovenia, April 14-16, 201

Experimental Dimensional Accuracy Analysis of Reformer Prototype Model Produced by FDM and SLA 3D Printing Technology

The subject of this paper is the evaluation of the dimensional accuracy of FDM and SLA 3D printing technologies in comparison with developed reformer polymer electrolyte membrane (PEM) fuel cell CAD model. 3D printing technologies allow a bottom-up approach to manufacturing, by depositing material in layers to final shape. Dimensional inaccuracy is still a problem in 3D printing technologies due to material shrinking and residual stress. Materials used in this research are PLA (Polylactic Acid) for FDM technology and the standard white resin material for SLA technology. Both materials are commonly used for 3D printing. PLA material is printed in three different height resolutions: 0.3 mm, 0.2 mm and 0.1 mm. White resin is printed in 0.1 mm height resolution. The aim of this paper is to show how layer height affects the dimensional accuracy of FDM models and to compare the dimensional accuracy of FDM and SLA printed reformer models with the same height resolution

Lyme Neuroborreliosis - Diagnosis and Treatment

Lyme neuroborreliosis, the infection of the nervous system by the tick-borne bacterium Borrelia burgdorferi, is a common infection in the temperate parts of the Northern hemisphere. Manifestations of the disease include facial palsy, radicular pain, sensory disturbances, and occasionally CNS symptoms such as confusion and paraparesis. The diagnosis of Lyme neuroborreliosis is based on medical history, clinical examination and cerebrospinal fluid (CSF) analysis. Recommended antibiotic treatment is oral doxycycline or intravenous ceftriaxone. The overall aims of this thesis were to improve the diagnosis and treatment of Lyme neuroborreliosis. In paper I, 102 patients with peripheral facial palsy were studied. Onset of symptoms in July to October, additional neurological symptoms and CSF pleocytosis were factors that discriminate patients with peripheral facial palsy caused by Lyme neuroborreliosis from patients with Bell’s palsy. In paper II, it was shown that CSF levels of the chemokine CXCL13 are highly elevated in Lyme neuroborreliosis and that levels decline after treatment, but high and overlapping CXCL13 levels were also seen in patients with asymptomatic HIV-infection and the decrease in CXCL13 is correlated to the decrease in CSF cell count. The additional diagnostic value of CXCL13 analysis is therefore limited. In paper III, new reference ranges for CSF cell counts when analyzed with automatic cell counters were determined, based on CSF sampling of 80 healthy volunteers. The differentiation of mononuclear cells into lymphocytes and monocytes was shown to be of limited value in the discrimination between Lyme neuroborreliosis and viral CNS infections. In paper IV, it was shown that treatment with oral doxycycline resulted in a similar decrease in CSF mononuclear cell counts in patients with Lyme neuroborreliosis with CNS symptoms compared with patients with peripheral nervous systems symptoms, and that all patients with CNS symptoms improved on treatment with no need for retreatment. Oral doxycycline can therefore be considered an effective treatment for Lyme neuroborreliosis, irrespective of the severity of symptoms