Charles Scot Sherrington, O.M.; 1857-1952.
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Exposure to moderate concentrations (90-500 microg SO(2) m(-3)) of SO(2) for 5-30 days caused a decrease in the photosynthetic rate. Only the lowest concentration (30 microg SO(2) m(-3)) increased photosynthesis. There was hardly any recovery in photosynthesis after the exposure. All exposure concentrations increased dark respiration. However, the lowest concentration had the smallest effect. Exposure to high concentration (2320 microg SO(2) m(-3)) of SO(2) for 5 h caused a strong decrease in the photosynthetic rate but there was a complete recovery within 2 weeks.
The effects of simulated acid rain on the phyllosphere microflora of pine (Pinus sylvestris L.) were studied experimentally in northern Finland during the summer of 1988. Trees were irrigated with artificial acid rain of pH4 and pH3 (H(2)SO(4) and HNO(3), weight ratio of S:N=2.86:1). Untreated trees and trees irrigated with spring water (pH6) were used as controls. Two sampling heights (0.5m and 2m) were used. The needles were colonized exclusively by epiphytic fungi, mainly Aureobasidium pullulans (de Bary) Arnaud. The lower branches had significantly more epiphytic fungi than the upper branches. Compared to the control trees, the numbers of epiphytic fungi were significantly decreased on the needles of trees irrigated with acid rain. Acid rain affected the number of epiphytic fungi equally at both sampling heights. The species composition of the epiphytic fungi was not affected by the acid treatments.
The population dynamics of conifer aphids on pine and spruce seedlings growing in plastic pots were studied along a gradient from a pulp mill emitting mainly SO(2). At five locations, two apterous females of the grey pine aphid (Schizolachnus pineti L.) feeding on needles, and two apterous females of the spruce shoot aphid (Cinara pilicornis Hartig) feeding on the stem, were transferred to the leader shoot of 10 pine and spruce seedlings, respectively. The sulphur concentrations of the transplanted lichen Hypogymnia physodes (L.) Nyl. and needles of conifer seedlings were significantly increased in the close vicinity of the pulp mill. On pine seedlings, the numbers of S. pineti developed similarly at all study sites. However, in mid-July, the numbers of aphids started to decline near the emission source. In June, C. pilicornis reproduction on spruce was significantly faster at 0.2 and 0.5 km from the pollution source than at the more distant sites, but there was a rapid decline in aphid numbers in July. A negative correlation was observed between the numbers of C. pilicornis during the population peak in late June and the final length of the current year's leader shoot of spruce seedlings. Leader shoot growth of spruce seedlings infested by aphids was positively correlated with the distance from the pulp mill. There were no clear responses to pollution level in parasitization or predation rates of the aphids. The results suggest that all conifer aphids are not good indicators of pollution impact on conifers around a pollution source. There is a general agreement with the earlier reports that Cinara spp. numbers have a positive response to air pollution, especially to SO(2). This is probably due to promoted growth of nymphal aphids on the host plants suffering from pollution. However, high levels of air pollution may also cause rapid collapse of aphid populations. S. pineti, which lives on foliage, did not have a positive response to increased SO(2) levels.
A comparison was made of the suicide rates and methods for the period 1962-1971 of migrants in Australia from England and Wales, Scotland and Ireland with those in their country of origin. Suicide rates for all three migrant groups were very similar to each other, although greater than in their country of origin especially those for Eire. The data suggest that the official lower rates in Scotland compared with England and Wales are due to ascertainment differences. Similar conclusions were drawn regarding the official rates in Eire. Several hypotheses were raised regarding the influence of religion on suicide rates in Eire, Northern Ireland and Australia.
A model for inducing partial (PBI) or global brain ischemia (GBI) in awake or anesthetized rats was obtained by ligating one subclavian and both carotid arteries (for PBI) or both subclavian-carotid arteries (for GBI). Rats were intubated and ventilated mechanically then subjected to a midline ventral incision from larynx to xiphoid process. The thorax was entered to expose the aortic arch and either one or both subclavians were ligated to eliminate each vertebral artery supply to brain. After chest closure the common carotid arteries were exposed and immediately ligated or else catheter snares were installed to induce ischemia at a later date. PBI was induced in 3 groups of rats for 7, 30 and 60 days while GBI was given for 5, 10, 30 and 75 minutes in 4 other groups. EEG became flat within 15 seconds after GBI and cortical cerebral blood flow (CBF) was reduced to "zero." EEG was unaffected after PBI but cortical CBF was reduced from a mean 118 ml/100 g tissue/min to 77 ml after 7 days. Morphological damage of CA1 hippocampal neurons after GBI or PBI was found reproducible and time dependent on ischemic duration. Acute cell damage rose from 5-95% in CA1 as GBI duration increased from 5-75 minutes. Similarly, chronic cell damage of CA1 increased as ischemic duration continued from 7-60 days in rats subjected to PBI. The advantages of the present model provide the option of inducing partial or global brain ischemia and of introducing postischemic reperfusion in awake or anesthetized preparations without the use of drugs, blood pressure manipulation or direct contact with brain tissue.(ABSTRACT TRUNCATED AT 250 WORDS)
Twenty years after the Chernobyl accident, root uptake from the surface layers of contaminated forest soils plays a major role in radiocaesium ((137)Cs) transfer to the trees and accumulation in perennial compartments, including stemwood. Trustworthy long-term predictions (modelling) of stemwood contamination with (137)Cs should accordingly be based on a reliable picture of this source-sink relationship. Considering the complexity of the processes involved in (137)Cs cycling in forest stands, elementary ratios like transfer factors (TF) were shown to be not very relevant for that purpose. At the tree level, alternatives like the wood immobilisation potential (WIP) have therefore been proposed in order to quantify the current net (137)Cs accumulation in stemwood. Our objective was here to compare WIP values determined for a series of contaminated forest stands in Belarus with the corresponding pools of (137)Cs available in the soil for root uptake. The comparison reveals that both indices are quite proportional, whatever the forest ecosystem features. This corroborates the relevancy of WIP as an indicator of the current (137)Cs root uptake by the trees, which could accordingly help to improve the existing models of (137)Cs cycling and the long-term management of contaminated forest ecosystems.
In a short period of time, the law in Scotland has developed in two ways. Firstly, the law changed recently to allow the prosecution of a husband where a couple were in fact separated at the time of the rape. Secondly, the law moved forward again to the present position where a charge of rape is competent even if the couple are living together at the time of the incident complained of.
Urinary symptoms and the extent to which they interfere with living activities were compared in 2 community-based investigations that enrolled men 40 to 79 years old who were randomly sampled from Olmsted County, Minnesota (2,119) and the Forth Valley of Scotland (1,385). Both investigations included symptom questions with wording that is nearly identical to that of the American Urological Association (AUA) symptom index. Following AUA scoring conventions we grouped scores into mild (AUA score 0 to 7), moderate (score 8 to 19) and severe (score 20+) categories. Minnesota men had symptoms that were more frequent, more bothersome and caused greater interference with living activities than did Scottish men of comparable age (p < 0.0002). However, within each symptom score category, the extent to which symptoms interfered with living activities was essentially the same in both populations. Although there appear to be important differences in urinary symptom prevalence between Scotland and Minnesota, the AUA symptom index provides a consistent measure of the extent to which urinary symptoms interfere with living activities in both populations. These findings support use of the AUA symptom index in the diagnostic evaluation of men with benign prostatic hyperplasia.
There is still much to find out about how trees react to changing nutrient conditions. In this cation uptake study, 134Cs and 22Na were injected between the humus and the mineral soil, and into a 20-cm depth in the mineral soil, respectively. Half of the experimental site was subjected to desiccation in 1995 and 1996, while the other half was subjected to irrigation in 1995, and desiccation in 1996. One month after the injections, the concentration of 134Cs in the xylem sap was higher in the irrigated plots (ID) than in the desiccated plots (DD). In August 1995, the difference in the 134Cs concentration in the xylem sap was even higher between the treatments. In 1995, 22Na was also higher in the xylem sap on the ID plots than on the DD plots, but not significantly. Exponential relationships were found between the amount of 134Cs and 22Na in the xylem sap; the relative water uptake from humus and 0-10-cm mineral soil (134Cs); and 10-25-cm mineral soil (22Na) in July 1995, when the tracers had not yet reached the top of the boles. The relative uptake of injected 22Na was larger than that of injected 134Cs, probably due to low exchangeability of Cs in the soil. One year after the injection (1996), more 134Cs was found in the wood, bark, needles and cones on the plots irrigated in 1995 than on the desiccated plots. The content of 134Cs in the stem wood and stump amounted to nearly 80% of the total uptake in the trees. The Cs distribution 1 year after the Chernobyl accident was dominated by Cs on/in needles and bark. After 10 years of redistribution, the Chernobyl Cs content of the different parts of the trees approached that of K.
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Bulk precipitation and stand throughfall were collected during 1992-96 at distances of 0.5, 4 and 8 km from the Harjavalta Cu-Ni smelter, southwestern Finland. The amounts of heavy metals (Cu, Ni, Zn, Fe) and mineral nutrients in bulk precipitation and throughfall were highest at 0.5 km. Although the canopy coverage was low at 0.5 km, the amounts of heavy metals intercepted by the canopy were extremely high. The proportion of foliar leaching relative to the wash-off of dry deposition from the needle surfaces decreased on moving towards the smelter for all elements, except for K. The high rate of K leaching from the needle tissues close to the smelter demonstrated that the K throughfall flux has been greatly altered by the heavy pollution load.
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Extension growth of secondary needles is under photoperiodic control in Pinus sylvestris. To test for the effects of far-red light on maintaining this extension growth, seedlings of six populations originating from latitudes between 57 degrees and 67 degrees N were raised for 11 weeks in continuous incandescent (metal halogen) light at 300 &mgr;mol m-2 s-1 and 20 degrees C and then transferred at the same temperature to a daily regime of 8 h incandescent light (230 &mgr;mol m-2 s-1) followed by a 16 h day extension with cool white fluorescent light (40 &mgr;mol m-2 s-1, R/FR ratio 7.5) or with incandescent lamps (20 &mgr;mol m-2 s-1, R/FR ratio 2.0). For the seedlings from the three populations north of 64 degrees, needle extension growth over 42 days in the FR-poor day extension treatment was lower by up to 40% than in the FR-rich day extension treatment, whereas for the seedlings from the three southern populations the needle extension growth was similar in both day extension treatments. The requirement for FR in day extensions is characteristic of 'light-dominant' photoperiodic control mechanisms. It appears that P. sylvestris changes from dark-dominant night timekeeping to light-dominant day timekeeping with increasing latitude, as with the photoperiodic control of budset in Picea abies.
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