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  • 1
    ISSN: 0942-0940
    Keywords: Age ; Doppler velocimetry ; subarachnoid haemorrhage ; vasospasm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A retrospective analysis was undertaken to determine whether cerebral vasospasm following subarachnoid haemorrhage (SAH) correlates with the age of patients. For at least 3 weeks after bleeding 80 subjects underwent very close follow-up with clinical examination and transcranial Doppler records of the blood velocities within the basal cerebral arteries. Firstly a correlation between measured maximal mean blood flow velocities and age was made. Secondly, according to their age and the maximum of recorded mean velocitites (v), the patients were divided into groups as follows: age 55 years or less, age more than 55 years; and maximum velocity v1〈90cm/s, 90cm/s〈v2〈120cm/s, 120cm/s〈v3〈160cm/s, v4〉160cm/s. There was a significant correlation of the measured maximum mean velocities and the age of the patients (r =−0.525, p〈0.01). With regard to the velocity groups there was a significant (chisquared statistic for contingency tables, p〈0.01) difference between both age-groups: 32% (n=18) of the younger fell into group v4 with maximum mean velocities of more than 160cm/s, but none of the older had such. Vice versa, 63% (n=15) of the older compared with only 14% (n=8) of the younger fell into group v1 with maximum mean velocities of less than 90 cm/s. Clinical follow-up also depicted differences between both age groups. 13 of 18 younger patients with maximum mean velocities 〉160 cm/s exhibited symptomatic vasospasm with a delayed neurological deficit. This typical course did not occur in the older age group. We conclude from this analysis that the increase of blood velocity in the basal cerebral arteries following subarachnoid haemorrhage depends on the age of the patient. Furthermore, young patients will be more prone to a delayed ischaemic deficit. On the other hand, older patients may also suffer ischaemic deficits following subarachnoid haemorrhage but often without measurable vasospasm according to transcranial Doppler criteria and without the typical delayed appearance.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 84 (1985), S. 175-179 
    ISSN: 1573-5036
    Keywords: Biomas ; Drying ; Mineralization ; Nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Drying soil to −100 kPa increased the subsequent mineralization of nitrogen under optimal moisture conditions. The effect was greater when the soils were dried to −1500 Pa. Mineralization was greater after four cycles of wetting and drying than after one. Depending on the drying conditions, the amount of nitrogen mineralized after drying to −1500 Pa was between 6.8 and 18.2% of that mineralized after chloroform fumigation. After drying the soils the average ratio of ΔCO2-C respired to Δmin N was 21.1–22.3 depending on the drying conditions, whereas after chloroform treatment and autoclaving the ratio was 6.0 and 9.9 respectively. The effect of drying on nitrogen mineralization is attributed to two causes: the death and subsequent lysis of a small proportion of the soil organisms, and to the desorption of organic substances with a wide C/N ratio. Because of the stimulation of even mild drying conditions, marked differences in mineralization rates of soil nitrogen between cropping seasons must be expected.
    Type of Medium: Electronic Resource
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