Motor imagery training improves precision of an upper limb movement in patients with hemiparesis

BACKGROUND: In healthy participants, beneficial effects of motor imagery training on movement execution have been shown for precision, strength, and speed. In the clinical context, it is still debated whether motor imagery provides an effective rehabilitation technique in patients with motor deficits.OBJECTIVE: To compare the effectiveness of two different types of movement training: motor imagery vs. motor execution.METHODS: Twenty-five patients with hemiparesis were assigned to one of two training groups: the imagery or the execution-training group. Both groups completed a baseline test before they received six training sessions, each of which was followed by a test session. Using a novel and precisely quantifiable test, we assessed how accurately patients performed an upper limb movement. RESULTS: Both training groups improved performance over the six test sessions but the improvement was significantly larger in the imagery group. That is, the imagery group was able to perform more precise movements than the execution group after the sixth training session while there was no difference at the beginning of the training.CONCLUSIONS: The results provide evidence for the benefit of motor imagery training in patients with hemiparesis and thus suggest the integration of cognitive training in conventional physiotherapy practice

Test your surrogate data before you test for nonlinearity

The schemes for the generation of surrogate data in order to test the null hypothesis of linear stochastic process undergoing nonlinear static transform are investigated as to their consistency in representing the null hypothesis. In particular, we pinpoint some important caveats of the prominent algorithm of amplitude adjusted Fourier transform surrogates (AAFT) and compare it to the iterated AAFT (IAAFT), which is more consistent in representing the null hypothesis. It turns out that in many applications with real data the inferences of nonlinearity after marginal rejection of the null hypothesis were premature and have to be re-investigated taken into account the inaccuracies in the AAFT algorithm, mainly concerning the mismatching of the linear correlations. In order to deal with such inaccuracies we propose the use of linear together with nonlinear polynomials as discriminating statistics. The application of this setup to some well-known real data sets cautions against the use of the AAFT algorithm.Comment: 14 pages, 15 figures, submitted to Physical Review

Calcifediol versus vitamin D3 effects on gait speed and trunk sway in young postmenopausal women: a double-blind randomized controlled trial

UNLABELLED In this double-blind RCT, 4-month treatment with calcifediol compared with vitamin D3 improved gait speed by 18 % among young postmenopausal women. Consistently, change in 25(OH)D blood levels over time were significantly correlated with improvement in gait speed in these women. No effect could be demonstrated for trunk sway. INTRODUCTION The aim of this study is to test the effect of calcifediol compared with vitamin D3 on gait speed and trunk sway. METHODS Twenty healthy postmenopausal women with an average 25(OH)D level of 13.2 ng/ml (SD = ±3.9) and a mean age of 61.5 years (SD = ±7.2) were randomized to either 20 μg of calcifediol or 20 μg (800 IU) of vitamin D3 per day in a double-blind manner. At baseline and at 4 months of follow-up, the same physiotherapist blinded to treatment allocation tested 8-m gait speed and a body sway test battery (Sway star pitch and roll angle plus velocity while walking 8 m, and standing on both legs on a hard and soft surface). All analyses adjusted for baseline measurement, age, and body mass index. RESULTS Mean 25(OH)D levels increased to 69.3 ng/ml (SD = ±9.5) in the calcifediol group and to 30.5 ng/ml (SD = ±5.0) in the vitamin D3 group (p < 0.0001). Women receiving calcifediol compared with vitamin D3 had an 18 % greater improvement in gait speed at 4-month follow-up (p = 0.046) adjusting for baseline gait speed, age, and body mass index. Also, change in gait speed was significantly correlated with change in serum 25(OH)D concentrations (r = 0.5; p = 0.04). Across three tests of trunk sway, there were no consistent differences between groups and no significant correlation between change in 25(OH)D serum concentrations and change in trunk sway. CONCLUSIONS Calcifediol improved gait speed in early postmenopausal women compared with vitamin D3 and change in 25(OH)D level was moderately correlated with improvement in gait speed. A benefit on trunk sway could not be demonstrated

Quantitative analysis by renormalized entropy of invasive electroencephalograph recordings in focal epilepsy

Invasive electroencephalograph (EEG) recordings of ten patients suffering from focal epilepsy were analyzed using the method of renormalized entropy. Introduced as a complexity measure for the different regimes of a dynamical system, the feature was tested here for its spatio-temporal behavior in epileptic seizures. In all patients a decrease of renormalized entropy within the ictal phase of seizure was found. Furthermore, the strength of this decrease is monotonically related to the distance of the recording location to the focus. The results suggest that the method of renormalized entropy is a useful procedure for clinical applications like seizure detection and localization of epileptic foci.Comment: 10 pages, 5 figure

Predictive Value of Bronchoalveolar Lavage in Excluding a Diagnosis of Pneumocystis carinii Pneumonia During Prophylaxis with Aerosolized Pentamidine

We assessed the negative predictive value of bronchoalveolar lavage (BAL) for Pneumocystis carinii pneumonia (PCP) during prophylaxis with aerosolized pentamidine. On the basis of the assumption that undiagnosed and untreated PCP would progress and become clinically apparent, for 3 months we prospectively followed 34 consecutive cases in which BAL had not detected PCP. All patients were immunodeficient, had a symptomatic human immunodeficiency virus infection, and were evaluated for possible PCP during prophylaxis with aerosolized pentamidine. No transbronchial biopsies were performed. In 32 of 34 cases, a diagnosis of PCP could be excluded because of other definite diagnoses or improvement during the follow-up. Despite negative results of an examination of their BAL fluid, two patients received empirical treatment that was active against PCP; these patients were regarded as possibly having undiagnosed PCP. Thus, the negative predictive value of BAL alone was at least 94% (32 of 34 cases) in excluding a diagnosis of PCP during prophylaxis with aerosolized pentamidin

Scaling of avalanche queues in directed dissipative sandpiles

We simulate queues of activity in a directed sandpile automaton in 1+1 dimensions by adding grains at the top row with driving rate $0 < r \leq 1$. The duration of elementary avalanches is exactly described by the distribution $P_1(t) \sim t^{-3/2}\exp{(-1/L_c)}$, limited either by the system size or by dissipation at defects $L_c= \min (L,\xi)$. Recognizing the probability $P_1$ as a distribution of service time of jobs arriving at a server with frequency $r$, the model represents a new example of the $$ server queue in the queue theory. We study numerically and analytically the tail behavior of the distributions of busy periods and energy dissipated in the queue and the probability of an infinite queue as a function of driving rate.Comment: 11 pages, 9 figures; To appear in Phys. Rev.

Is fall prevention by vitamin D mediated by a change in postural or dynamic balance?

Introduction: The objectives were:(1) to validate a quantitative balance assessment method for fall risk prediction; (2) to investigate whether the effect of vitamin D and calcium on the risk of falling is mediated through postural or dynamic balance, as assessed by this method. Materials and methods: A secondary analysis of a double blind randomized controlled trial was employed, which included 64 institutionalized elderly women with complete balance assessment (age range: 65-97; mean 25-hydroxyvitamin D levels: 16.4ng/ml (SD ±9.9). Participants received 1,200mg calcium plus 800IU cholecalciferol (n=33) or 1,200mg calcium (n=31) per day over a 3-month treatment period. Using an electronic device attached to the lower back of the participant, balance was assessed as the degree of trunk angular displacement and angular velocity during a postural task (standing on two legs, eyes open, for 20 s) and a dynamic task (get up from a standard height chair with arm rests, sit down and then stand up again and remain standing). Results: It was found that both postural and dynamic balance independently and significantly predicted the rate of falling within the 3-month follow-up. Vitamin D plus calcium reduced the rate of falls by 60% [relative risk (RR)=0.40; 95% CI: 0.17, 0.94] if compared with calcium alone. Once postural and dynamic balance were added to the regression analysis, they both attenuated the effect of vitamin D plus calcium on the rate of falls. For postural balance, the RR changed by 22% from 0.40 to 0.62 if angular displacement was added to the model, and by 9% from 0.40 to 0.49 if angular velocity was added. For dynamic balance, it changed by 1% from 0.40 to 0.41 if angular displacement was added, and by 14% from 0.40 to 0.54 if angular velocity was added. Discussion: Thus, balance assessment using trunk angular displacement is a valid method for the prediction of falls in older women. Of the observed 60% reduction in the rate of falls by vitamin D plus calcium supplementation compared with calcium alone, up to 22% of the treatment effect was explained by a change in postural balance and up to 14% by dynamic balanc

Radial localization of edge modes in Alcator C-Mod pedestals using optical diagnostics

Dedicated experiments in ion cyclotron range heated enhanced D-alpha (EDA) H-mode and I-mode plasmas have been performed on Alcator C-Mod to identify the location of edge fluctuations inside the pedestal and to determine their plasma frame phase velocity. For this purpose, measurements from gas puff imaging (GPI) and gas puff charge exchange recombination spectroscopy (GP-CXRS) have been collected using the same optical views. The data suggest that the EDA H-mode-specific quasi-coherent mode (QCM) is centered near the radial electric field (E r) well minimum and propagates along the ion diamagnetic drift direction in the plasma frame. The weakly coherent mode (WCM) and the geodesic acoustic mode observed in I-mode, on the other hand, are found to be located around the outer shear layer of the E r well. This results in a weak plasma frame phase velocity mostly along the electron diamagnetic drift direction for the WCM. The findings in these EDA H-mode plasmas differ from probe measurements in ohmic EDA H-mode (LaBombard et al 2014 Phys. Plasmas 21 056108), where the QCM was identified as an electron drift-wave located several mm outside the E r well minimum in a region of positive E r. To explore if instrumental effects of the optical diagnostics could be the cause of the difference, a synthetic diagnostic for GPI is introduced. This diagnostic reproduces amplitude ratios and relative radial shifts of the mode profiles determined from poloidally and toroidally oriented optics and, if instrumental effects related to GP-CXRS are also included, indicates that the measured location of the QCM and WCM relative to the E r well reported here is only weakly affected by instrumental effects

Don't bleach chaotic data

A common first step in time series signal analysis involves digitally filtering the data to remove linear correlations. The residual data is spectrally white (it is ``bleached''), but in principle retains the nonlinear structure of the original time series. It is well known that simple linear autocorrelation can give rise to spurious results in algorithms for estimating nonlinear invariants, such as fractal dimension and Lyapunov exponents. In theory, bleached data avoids these pitfalls. But in practice, bleaching obscures the underlying deterministic structure of a low-dimensional chaotic process. This appears to be a property of the chaos itself, since nonchaotic data are not similarly affected. The adverse effects of bleaching are demonstrated in a series of numerical experiments on known chaotic data. Some theoretical aspects are also discussed.Comment: 12 dense pages (82K) of ordinary LaTeX; uses macro psfig.tex for inclusion of figures in text; figures are uufile'd into a single file of size 306K; the final dvips'd postscript file is about 1.3mb Replaced 9/30/93 to incorporate final changes in the proofs and to make the LaTeX more portable; the paper will appear in CHAOS 4 (Dec, 1993

On the Nature of X-ray Variability in Ark 564

We use data from a recent long ASCA observation of the Narrow Line Seyfert 1 Ark 564 to investigate in detail its timing properties. We show that a thorough analysis of the time series, employing techniques not generally applied to AGN light curves, can provide useful information to characterize the engines of these powerful sources.We searched for signs of non-stationarity in the data, but did not find strong evidences for it. We find that the process causing the variability is very likely nonlinear, suggesting that variability models based on many active regions, as the shot noise model, may not be applicable to Ark 564. The complex light curve can be viewed, for a limited range of time scales, as a fractal object with non-trivial fractal dimension and statistical self-similarity. Finally, using a nonlinear statistic based on the scaling index as a tool to discriminate time series, we demonstrate that the high and low count rate states, which are indistinguishable on the basis of their autocorrelation, structure and probability density functions, are intrinsically different, with the high state characterized by higher complexity.Comment: 13 pages, 13 figures, accepted for publication in A&