Gaze fixation improves the stability of expert juggling

Novice and expert jugglers employ different visuomotor strategies: whereas novices look at the balls around their zeniths, experts tend to fixate their gaze at a central location within the pattern (so-called gaze-through). A gaze-through strategy may reflect visuomotor parsimony, i.e., the use of simpler visuomotor (oculomotor and/or attentional) strategies as afforded by superior tossing accuracy and error corrections. In addition, the more stable gaze during a gaze-through strategy may result in more accurate movement planning by providing a stable base for gaze-centered neural coding of ball motion and movement plans or for shifts in attention. To determine whether a stable gaze might indeed have such beneficial effects on juggling, we examined juggling variability during 3-ball cascade juggling with and without constrained gaze fixation (at various depths) in expert performers (n = 5). Novice jugglers were included (n = 5) for comparison, even though our predictions pertained specifically to expert juggling. We indeed observed that experts, but not novices, juggled significantly less variable when fixating, compared to unconstrained viewing. Thus, while visuomotor parsimony might still contribute to the emergence of a gaze-through strategy, this study highlights an additional role for improved movement planning. This role may be engendered by gaze-centered coding and/or attentional control mechanisms in the brain

Revisiting QRS detection methodologies for portable, wearable, battery-operated, and wireless ECG systems

Cardiovascular diseases are the number one cause of death worldwide. Currently, portable battery-operated systems such as mobile phones with wireless ECG sensors have the potential to be used in continuous cardiac function assessment that can be easily integrated into daily life. These portable point-of-care diagnostic systems can therefore help unveil and treat cardiovascular diseases. The basis for ECG analysis is a robust detection of the prominent QRS complex, as well as other ECG signal characteristics. However, it is not clear from the literature which ECG analysis algorithms are suited for an implementation on a mobile device. We investigate current QRS detection algorithms based on three assessment criteria: 1) robustness to noise, 2) parameter choice, and 3) numerical efficiency, in order to target a universal fast-robust detector. Furthermore, existing QRS detection algorithms may provide an acceptable solution only on small segments of ECG signals, within a certain amplitude range, or amid particular types of arrhythmia and/or noise. These issues are discussed in the context of a comparison with the most conventional algorithms, followed by future recommendations for developing reliable QRS detection schemes suitable for implementation on battery-operated mobile devices.Mohamed Elgendi, Björn Eskofier, Socrates Dokos, Derek Abbot

Vegetative background of sleep: Spectral analysis of the heart rate variability

Phasic events during sleep, either arousal or REM-burst related, and the associated transient cardiovascular responses have been the subject of intensive research in previous studies. However, nontransient (stationary) fluctuations in heart rate have been studied less extensively in the past. They allow a differentiation of the sympathetic and parasympathetic activation, which are related to a low-frequency (LF) and a high-frequency (HF) component of the heart rate variability (HRV) signal, respectively. The resulting LF/HF ratio is a quantitative index of the sympatho-vagal balance. Sleep polygrams from 20 healthy volunteers were recorded in a sleep laboratory. Standard vegetative tests (orthostatic and Valsalva tests) were evaluated. A segmentation procedure, performed on the HRV signal, separated 70-130 transients during the night from the records of stationary heart rate fluctuations. From these periods the sympatho-vagal balance, quantified by the LF/HF, was computed by means of spectral analysis. The more synchronized the sleep was, the more the LF/HF decreased, whereas the LF/HF was significantly increased during REM sleep,indicating a sympathetic predominance during this period. Such an increase was also evident during the last 15 min before REM sleep onset. Results suggest that spectral analysis of the HRV provides additional information of the ultradian rhythmic behavior of the autonomic nervous system function beyond the traditional cardiovascular measurements (mean heart rate, blood pressure, etc.). In contrast to these measurements, which generally show a continuously decreasing cardiovascular activity, as the night proceeds, the results of this study reveal a high sympathetic peak activity during the later REM sleep periods, which is comparable in magnitude to that found in the upright position in wakefulness. This activity may be associated to the well-known incidence peak of ischemic events in the early morning hours. (C) 1997 Elsevier Science Inc

Agglomeration Effects in Foreign Direct Investment and the Pollution Haven Hypothesis

Agglomeration effects, Congestion effects, Environmental regulation, Foreign direct investment, German manufacturing, Panel data, Pollution havens, F18, F23, Q52,