297 research outputs found
The effect of temperature on growth and development of cultivars of radish (Raphanus sativus L. var. radicula Pers.) under summer conditions.
During 1977, seven cultivars and strains were sown in glasshouses at temperatures of 10, 14, 17, 20, 23 and 26 deg C and harvested at five dates. Maximum leaf and dry-matter production occurred at 20 and 23 deg C, and maximum root growth initially at 20 and 23 deg C, but later at 17 deg C. Cultivar differences in rate of leaf and root growth were observed, and cultivar X environment interactions were apparent for leaf and root growth under summer conditions. The overall order of cultivars for leaf and root weight was similar to that for plants grown under autumn conditions [see PBA 47, 5915]; hence it is suggested that selection of plants for growing in winter could be performed during the summer. (Abstract retrieved from CAB Abstracts by CABI’s permission
Breeding for early root thickening of radish (Raphanus sativus L. var. radicula Pers.) under poor light conditions. I. Performance of F1 half-sib families at different temperatures in late autumn.
Twenty half-sib families, from early-thickening mother plants selected from four early cultivars in a late-autumn trial [see also PBA 47, 5915], were sown in the glasshouse with their parent types during October 1975, at 10, 14, 17 or 20 deg C. The optimum temperature for root thickening was 14 deg C, and significant differences were observed between families for average root diameter. The earliest families originated from mother plants selected from the early cultivars Rota and Robijn [Ruby]. It is suggested from the results that the autumn selection of plants with early root thickening could be used to obtain families with a shorter growing period under poor light conditions than the parent cultivars, and since the heritability of the breeding value was highest at 14 deg C, selection should be performed at this temperature. (Abstract retrieved from CAB Abstracts by CABI’s permission
The chronology of Anglo-Saxon style pottery in radiocarbon dates:Improving the typo-chronology
In the fourth and fifth centuries AD, the Anglo‐Saxon style was introduced in north‐western Europe. To what extent immigrants contributed to this process for each region is still debated. How and when the Anglo‐Saxon style spread is essential in this debate. Handmade pottery is the most common find category, but so far it can only be dated globally. An earlier and a later style have been postulated and the introduction of this pottery is seemingly not simultaneous in every region. Hitherto this could not be supported by the radiocarbon dates. The present study shows that, with the help of Bayesian modelling, it is possible to substantiate these patterns, which is of utmost importance for understanding migration patterns, contacts and exchange along the southern North Sea coastal regions during this period
Tremor pathophysiology:lessons from neuroimaging
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226036.pdf (Publisher’s version ) (Closed access)PURPOSE OF REVIEW: We discuss the latest neuroimaging studies investigating the pathophysiology of Parkinson's tremor, essential tremor, dystonic tremor and Holmes tremor. RECENT FINDINGS: Parkinson's tremor is associated with increased activity in the cerebello-thalamo-cortical circuit, with interindividual differences depending on the clinical dopamine response of the tremor. Although dopamine-resistant Parkinson's tremor arises from a larger contribution of the (dopamine-insensitive) cerebellum, dopamine-responsive tremor may be explained by thalamic dopamine depletion. In essential tremor, deep brain stimulation normalizes cerebellar overactivity, which fits with the cerebellar oscillator hypothesis. On the other hand, disconnection of the dentate nucleus and abnormal white matter microstructural integrity support a decoupling of the cerebellum in essential tremor. In dystonic tremor, there is evidence for involvement of both cerebellum and basal ganglia, although this may depend on the clinical phenotype. Finally, in Holmes tremor, different causal lesions map to a common network consisting of the red nucleus, internal globus pallidus, thalamus, cerebellum and pontomedullary junction. SUMMARY: The pathophysiology of all investigated tremors involves the cerebello-thalamo-cortical pathway, and clinical and pathophysiological features overlap among tremor disorders. We draw the outlines of a hypothetical pathophysiological axis, which may be used besides clinical features and cause in future tremor classifications
Increased frontal brain activation during walking while dual tasking: an fNIRS study in healthy young adults
Background: Accumulating evidence suggests that gait is influenced by higher order cognitive and cortical control mechanisms. Recently, several studies used functional near infrared spectroscopy (fNIRS) to examine brain activity during walking, demonstrating increased oxygenated hemoglobin (HbO2) levels in the frontal cortex during walking while subjects completed a verbal cognitive task. It is, however, still unclear whether this increase in activation was related to verbalization, if the response was specific to gait, or if it would also be observed during standing, a different motor control task. The aim of this study was to investigate whether an increase in frontal activation is specific to dual tasking during walking. Methods: Twenty-three healthy young adults (mean 30.9 ± 3.7 yrs, 13 females) were assessed using an electronic walkway. Frontal brain activation was assessed using an fNIRS system consisting of two probes placed on the forehead of the subjects. Assessments included: walking in a self-selected speed; walking while counting forward; walking while serially subtracting 7s (Walking+S7); and standing while serially subtracting 7s (Standing+S7). Data was collected from 5 walks of 30 meters in each condition. Twenty seconds of quiet standing before each walk served as baseline frontal lobe activity. Repeated Measures Analysis of Variance (RM ANOVA) tested for differences between the conditions. Results: Significant differences were observed in HbO2 levels between all conditions (p = 0.007). HbO2 levels appeared to be graded; walking alone demonstrated the lowest levels of HbO2 followed by walking+counting condition (p = 0.03) followed by Walking+S7 condition significantly increased compared to the two other walking conditions (p < 0.01). No significant differences in HbO2 levels were observed between usual walking and the standing condition (p = 0.38) or between standing with or without serial subtraction (p = 0.76). Conclusions: This study provides direct evidence that dual tasking during walking is associated with frontal brain activation in healthy young adults. The observed changes are apparently not a response to the verbalization of words and are related to the cognitive load during gait
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