Suppression of Pythium and Phytophthora damping-off of rooibos by compost and a combination of compost and nonpathogenic <I>Pythium </I>taxa

Please help populate SUNScholar with the full text of SU research output. Also - should you need this item urgently, please send us the details and we will try to get hold of the full text as quick possible. E-mail to [email protected]. Thank you.Journal Articles (subsidised)AgriwetenskappePlantpatologi

Lateralized responses during covert attention are modulated by target eccentricity

Contains fulltext : 99471.pdf (publisher's version ) (Closed access)Various studies have demonstrated that covert attention to different locations in the visual field can be used as a control signal for brain computer interfacing. It is well known that when covert attention is directed to the left visual hemifield, posterior alpha activity decreases in the right hemisphere while simultaneously increasing in the left hemisphere and vice versa. However, it remains unknown if and how the classical lateralization pattern depends on the eccentricity of the locations to which one attends. In this paper we study the effect of target eccentricity on the performance of a brain computer interface system that is driven by covert attention. Results show that the lateralization pattern becomes more pronounced as target eccentricity increases and suggest that in the current design the minimum eccentricity for having an acceptable classification performance for two targets at equal distance from fixation in opposite hemifields is about 6 degrees of visual angle

Distinct directional couplings between slow and fast gamma power to the phase of theta oscillations in the rat hippocampus

Contains fulltext : 218743.pdf (Publisher’s version ) (Closed access)It is well-established that theta (~4-10 Hz) and gamma (~25-100 Hz) oscillations interact in the rat hippocampus. This cross-frequency coupling might facilitate neuronal coordination both within and between brain areas. However, it remains unclear whether the phase of theta oscillations controls the power of slow and fast gamma activity or vice versa. We here applied spectral Granger causality, phase slope index and a newly developed cross-frequency directionality (CFD) measure to investigate directional interactions between local field potentials recorded within and across hippocampal subregions of CA1 and CA3 of freely exploring rats. Given the well-known CA3 to CA1 anatomical connection, we hypothesized that interregional directional interactions were constrained by anatomical connection, and within-frequency and cross-frequency directional interactions were always from CA3 to CA1. As expected, we found that CA3 drove CA1 in the theta band, and theta phase-to-gamma power coupling was prominent both within and between CA3 and CA1 regions. The CFD measure further demonstrated that distinct directional couplings with respect to theta phase was different between slow and fast gamma activity. Importantly, CA3 slow gamma power phase-adjusted CA1 theta oscillations, suggesting that slow gamma activity in CA3 entrains theta oscillations in CA1. In contrast, CA3 theta phase controls CA1 fast gamma activity, indicating that communication at CA1 fast gamma is coordinated by CA3 theta phase. Overall, these findings demonstrate dynamic directional interactions between theta and slow/fast gamma oscillations in the hippocampal network, suggesting that anatomical connections constrain the directional interactions.12 p

Modulations in alpha activity by covert attention: a new 2D control signal for BCI

Item does not contain fulltexthttp://www.enpmeeting.org/2009/ShowAbstractOnline.php?uai=8b77e5910329215929ENP 2009, 3 juni 200

<I>Pythium cederbergense </I>sp. nov. and related taxa from <I>Pythium </I>clade G associated with the South African indigenous plant <I>Aspalathus linearis </I>(rooibos)

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Evidence of interventions to increase muscle strength and improve gait after stroke

The overall purpose of this thesis was to provide clinical evidence, based on high quality research, regarding effects of interventions aimed at increasing muscle strength and improving gait after stroke. The definition of each study which comprised the thesis and its research design began by carefully reading the Clinical Guidelines for Stroke Management – a clinical guideline developed with the purpose of making clinical recommendations for prevention and treatment of patients after stroke. The rehabilitation chapter of the guideline was analyzed in order to understand the current level of evidence, to identify areas with lack of evidence, and to develop studies capable of providing evidence that could help clinical practice regarding muscle weakness and walking limitations after stroke. Four studies were planned: three systematic reviews and one experimental trial. The first study examined the effect of cyclical electrical stimulation on muscle strength and activities after stroke. The research questions were: Does electrical stimulation increase strength after stroke? Are any benefits maintained beyond the intervention period or carried over to activity? A systematic review with meta-analysis of randomised or controlled trials was conducted. Participants were adults who have had a stroke, and the intervention was cyclical electrical stimulation applied in order to increase muscle strength. The outcome measures were related to muscle strength and to activity. Sixteen trials, representing 17 relevant comparisons, were included in this systematic review. Effect sizes were calculated as standardised mean differences. Overall, electrical stimulation increased strength by a standardised mean difference (SMD) of 0.47 (95% CI 0.26 to 0.68) and this effect was maintained beyond the intervention period (SMD 0.33, 95% CI 0.07 to 0.60). Electrical stimulation also improved activity (SMD 0.30, 95% CI 0.05 to 0.56) and this effect was also maintained beyond the intervention period (SMD 0.38, 95% CI 0.09 to 0.66). The second study examined the effect of the addition of cueing of cadence to walking training for improving walking speed, stride length, cadence and symmetry after stroke. The research question was: After stroke, is walking training with cueing of cadence superior to walking training alone in improving walking speed, stride length, cadence and symmetry? A systematic review with meta-analysis of randomised or controlled trials was conducted. Participants were ambulatory adults who have had a stroke. The intervention was walking training with cueing of cadence, and four walking outcomes were of interest: walking speed, stride length, cadence and symmetry. This review included seven trials involving 211 participants. Because one trial caused substantial statistical heterogeneity, meta-analyses were conducted with and without this trial. Walking training with cueing of cadence improved walking speed by 0.23 m/s (95% CI 0.18 to 0.27, I2 = 0%), stride length by 0.21 m (95% CI 0.14 to 0.28, I2 = 18%), cadence by 19 steps/minute (95% CI 14 to 23, I2 = 40%), and symmetry by 15% (95% CI 3 to 26, random effects) more than walking training alone. The third study examined the effect of the addition of virtual reality-based training to walking training for improving walking speed after stroke. The research questions were: (i) Is walking training associated with virtual reality-based training effective in increasing walking speed after stroke? (ii) Is this type of intervention more effective in increasing walking speed, than non-virtual reality-based walking interventions? A systematic review with meta-analysis of randomised clinical trials was conducted. Participants were adults with chronic stroke and the experimental intervention was walking training associated with virtual reality-based training to increase walking speed. The outcome data regarding walking speed were extracted from the eligible trials and were combined using a meta-analysis approach. Seven trials, representing eight comparisons, were included in this systematic review. Overall, the virtual reality-based training increased walking speed by 0.17 m/s (IC 95% 0.08 to 0.26), compared with placebo/nothing or non-walking interventions. In addition, the virtual reality-based training increased walking speed by 0.15 m/s (IC 95% 0.05 to 0.24), compared with non-virtual reality walking interventions. The fourth study examined the effect of the provision of a cane to ambulatory people after stroke on walking speed, step length, and cadence. The research questions were: (i) What is the effect of the provision of a cane on speed, step length, and cadence in people with chronic stroke who are independently ambulatory? (ii) Is there a differential effect according to comfortable walking speed (0.8 m/s)? Twenty-four people with chronic stroke, who were not regular users of walking sticks, were evaluated under two different experimental conditions: walking with and without a cane. Walking was reported as speed (m/s), step length (m), and cadence (steps/min). Participants were categorized as slow (0.8 m/s). The provision of a cane to the intermediate walkers produced a 0.27 m/s (95% CI 0.18 to 0.36) increase in speed compared with the fast walkers, and a 0.12 m/s (95% CI 0.03 to 0.21) increase compared with the slow walkers. It also produced 0.05 m (95% CI 0.02 to 0.08) increase in step length and 20 steps/min (95% CI 12 to 28) increase in cadence compared with the fast walkers. The provision of a cane produced the most benefit in intermediate walkers, and was detrimental to the fast walkers. Canes can be prescribed to stroke survivors with moderate and severe walking limitations, but caution should be taken regarding their prescription for fast walkers

Event conjunction: How the hippocampus integrates episodic memories across event boundaries

Our lives are a continuous stream of experience. Our episodic memories, however, have a definitive beginning, middle and end. Theories of event segmentation suggest that salient changes in our environment produce event boundaries which partition the past from the present and, as a result, produce discretised memories. However, event boundaries cannot completely discretise two memories; any shared conceptual link will eagerly integrate these memories. Here, we present a new framework inspired by electrophysiological research that resolves this apparent contradiction. At its heart, the framework proposes that hippocampal theta-gamma coupling maintains a highly abstract model of an ongoing event and serves to encode this model as an episodic memory. When a second but related event begins, this theta-gamma model is rapidly reconstructed within the hippocampus where new details of the second event can be appended to the existing event model. The event conjunction framework is the first electrophysiological explanation of how event memories can be formed at, and integrated across, event boundaries

Exploring the impact of alternative feature representations on BCI classification

Contains fulltext : 75525.pdf (publisher's version ) (Closed access)ESANN'2009, 17 th European Symposium on Artificial Neural Networks Computational Intelligence and Machine Learning, Bruges (Belgium), 22 april 200