De Vries effect

De Vries effect anomalously high values of l4C activity (2% greater than in 1900s), at around 1710 and 1500 AD discovered in 1958 and causes not known. 

It has been shown that the radiocarbon content of the atmosphere varied systematically in the past so that the radiocarbon activity around 1,500 and 1,700 was approximately 2% higher than it was during the nineteenth century. This phenomenon has been termed the De Vries effect, and another such effect (called the Suess effect) has been observed in twentieth century activity and is ascribed to the introduction of dead CO2 into the atmosphere through the combustion of fossil fuels after the start of the Industrial Revolution (De Vries 1958). 

De Vries effects Relatively short-term variations in C activities. Also known as wiggles or warps in the time scale. 

A fuller rendering of the entire Holocene " C time scale now permits researchers to review more precisely the timing and characteristics of the de Vries wiggles over the last 10 milleimia. Figure 3 plots the series of defined Holocene time warps reflecting the time ranges of the de Vries effect perturbations. Figure 3 A represents 0 to 5000 BP and Fig. 3B represents the 5000 to 10,000 BP period in years. 

InFig. 3, twelve major and five intermediate de Vries effect perturbations canbe identified. Major de Vries effects have been defined as warps exceeding 250 solar years intermediate de Vries effects are those that exhibit ranges in excess of 140 solar years, andrttinorde Vries effects have ranges of less than 140 solaryears. The 17 major and intermediate de Vries perturbations have been assigned Roman... 

FIGURE 3A Holocene de Vries effects Ranges ( warps ) in calendar years obtained from the calibration of conventional ages 0- 000 BR [From Taylor et al. (1996). Development and extension of the calibration of the radiocarbon time scale, Quaternary Sd. Rev. (Quaternary Geochronol.) 15,655-668.)... 

Dzoljic, E., van Leeuwen, R., de Vries, R. Dzoljic, M. R. (1997). Vigilance and EEC power in rats effects of potent inhibitors of the neuronal nitric oxide synthase. Naunyn Schmiedebergs Arch. Pharmacol. 356, 56-61. 

Damsma, G., Westernik, B.H., de Vries, J.B., and Horn, A.S., The effect of systemically applied cholinergic drugs on the striatal release of dopamine and its metabolites, as determined by automated microdialysis in conscious rats, Neurosci. Lett., 89, 349, 1988. 

Welling GW, Meijer-Severs GJ, Helmus G, van Santen E, Tonk RH, de Vries-Hospers HG, van der Waaij D The effect of ceftriaxone on the anaerobic bacterial flora and the bacterial enzymatic activity in the intestinal tract. Infection 1991 19 313-316. 

Mourits MJ, Bockermann I, de Vries EG, van derZee AG, ten Hoor KA,van derGraaf WT, Sluiter WJ, Willemse PH (2002) Tamoxifen effects on subjective and psychosexual wellbeing, in a randomised breast cancer study comparing high-dose and standard-dose chemotherapy. Br J Cancer 86 1546-1550... 

However, it is possible that the heterocatalyst becomes the dominant one, either if it is more stable and thus formed in large excess, or if it is a more active, kinetically dominant catalyst. Recently, both Reetz et al. and Feringa/Min-naard/de Vries et al. have shown that this approach can be beneficial. Earlier attempts by Chen and Xiao using mixtures of monodentate phosphites based on bisphenol and a chiral alcohol were not successful [39]. In our experience, the majority of catalysts based on mixtures of monodentate ligands show a poorer performance than the individual homo-catalysts. However, in a few instances there is a positive effect. 

The Feringa/Minnaard/de Vries group has further extended the scope of this cinnamate hydrogenation (Table 36.4) [50]. In all cases, a pronounced effect of the added triarylphosphine was found usually, the best results were obtained with a combination of ligands 10 g or lOh in combination with ri-ortho-lolyl-... 

In spite of almost global attraction of the critical load concept, the quantitative assessment of critical load values is connected till now with some uncertainties. The phrase significant harmful effects in the definition of critical load is of course susceptible to interpretation, depending on the kind of effects considered and the amount of harm accepted (De Vries and Bakker, 1998a, 1998b). Regarding the effects considered in terrestrial ecosystems, a distinction can be made in effects on ... 

Terpstra, A. H. M., Lapre, J. A., de Vries, H. T., and Beynen, A. C. (2000a). Hypocholester-olemic effect of dietary psyllium in female rats. Ann. Nutr. Metab. 44, 223-238. 

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