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• Peat bogs have accumulated more atmospheric carbon (C) than any other terrestrial ecosystem today. Most of this C is associated with peat moss (Sphagnum) litter. Atmospheric nitrogen (N) deposition can decrease Sphagnum production, compromising the C sequestration capacity of peat bogs. The mechanisms underlying the reduced production are uncertain, necessitating multifactorial experiments. • We investigated whether glasshouse experiments are reliable proxies for field experiments for assessing interactions between N deposition and environment as controls on Sphagnum N concentration and production. We performed a meta-analysis over 115 glasshouse experiments and 107 field experiments. • We found that glasshouse and field experiments gave similar qualitative and quantitative estimates of changes in Sphagnum N concentration in response to N application. However, glasshouse-based estimates of changes in production--even qualitative assessments-- diverged from field experiments owing to a stronger N effect on production response in absence of vascular plants in the glasshouse, and a weaker N effect on production response in presence of vascular plants compared to field experiments. • Thus, although we need glasshouse experiments to study how interacting environmental factors affect the response of Sphagnum to increased N deposition, we need field experiments to properly quantify these effects.

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Peatlands in the northern hemisphere have accumulated more atmospheric carbon (C) during the Holocene than any other terrestrial ecosystem, making peatlands long-term C sinks of global importance. Projected increases in nitrogen (N) deposition and temperature make future accumulation rates uncertain. Here, we assessed the impact of N deposition on peatland C sequestration potential by investigating the effects of experimental N addition on Sphagnum moss. We employed meta-regressions to the results of 107 field experiments, accounting for sampling dependence in the data. We found that high N loading (comprising N application rate, experiment duration, background N deposition) depressed Sphagnum production relative to untreated controls. The interactive effects of presence of competitive vascular plants and high tissue N concentrations indicated intensified biotic interactions and altered nutrient stochiometry as mechanisms underlying the detrimental N effects. Importantly, a higher summer temperature (mean for July) and increased annual precipitation intensified the negative effects of N. The temperature effect was comparable to an experimental application of almost 4 g N m(-2) yr(-1) for each 1°C increase. Our results indicate that current rates of N deposition in a warmer environment will strongly inhibit C sequestration by Sphagnum-dominated vegetation.

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The authors designed and constructed device simulating the activity of the heart, based on periodic filling and emptying two rubber blowers a radioactive solution by means of two pistons in cylinders operated by two specially shaped cams. The phantom enables to control the correctness of the method and a computer programme for evaluating parameters of heart activity (ejection fraction, end-diastolic volume, pulse volume etc.) in balanced ventriculography performed by a scintillation camera coupled with a computer. The performed measurements have shown a very good agreement of the evaluated parameters with those set at the phantom. The designed device is of an original construction and was granted the author's certificate No. 238,298.

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Using the specific absorbed fractions reported by Smith and Warner, the radiation doses absorbed by the embryo in early pregnancy were calculated for various radiopharmaceuticals used in the diagnostic procedures of nuclear medicine. Radiopharmaceuticals are considered which are excreted predominantly through urine and cause the doses to the embryo to be 40%--90% higher than gonad doses. Also discussed are large differences of doses reported by various authors to the embryo by 99mTc-pertechnetate.

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Eighteen children (8 boys, 10 girls) aged 6-16 years were examined. In all of them the basic diagnosis was bronchiectasia. Catheterization of the lesser circulation global spirometric examination, and perfusion lung scintigraphy with 99mTc both before and 2--4 years after lung resection were performed. Operations performed: 14 cases of lobectomy, one of bilobectomy, three of pneumonectomy. In all of the 14 children after lobectomy the pulmonary arterial pressure remained normal even during exercise. In contrast to this, in the three children after pneumonectomy and in the one boy after bilobectomy the mean pulmonary arterial pressure exceeded 20 mmHg at rest or after exercise. The total pulmonary resistance, converted per square metre of body surface, was--with a single exception [4.7 units before surgery]--within normal limits; after minor resections it rather tended to decrease, whereas in two of four children after major resections it slightly increased. Postoperative perfusion lung scintigram revealed a worsening in comparison with the preoperative finding in practically all of the children. This worsening can be ascribed not only to the restriction of lung tissue, but also to a compensatory emphysema of the remaining parenchyma. In patients with bronchiectasia, extensive resections have uncertain long-term prognosis.

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