INNOVATION AND NATIONAL BROADBAND POLICIES: FACTS, FICTION AND UNANSWERED QUESTIONS IN THE NET NEUTRALITY DEBATE

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A meta-analysis of the investment-uncertainty relationship

In this article we use meta-analysis to investigate the investment-uncertainty relationship. We focus on the direction and statistical significance of empirical estimates. Specifically, we estimate an ordered probit model and transform the estimated coefficients into marginal effects to reflect the changes in the probability of finding a significantly negative estimate, an insignificant estimate, or a significantly positive estimate. Exploratory data analysis shows that there is little empirical evidence for a positive relationship. The regression results suggest that the source of uncertainty, the level of data aggregation, the underlying model specification, and differences between short- and long-run effects are important sources of variation in study outcomes. These findings are, by and large, robust to the introduction of a trend variable to capture publication trends in the literature. The probability of finding a significantly negative relationship is higher in more recently published studies. JEL Classification: D21, D80, E22 1

INNOVATION AND NATIONAL BROADBAND POLICIES: FACTS, FICTION AND UNANSWERED QUESTIONS IN THE NET NEUTRALITY DEBATE

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D.: The effect of lutein and zeaxanthin supplementation on metabolites of these carotenoids

PURPOSE. To investigate the effect of lutein supplementation at doses of 2.5, 5.0, and 10 mg/d for 6 months on distribution of these carotenoids and their metabolites in the serum of elderly human subjects, with and without age-related macular degeneration. To determine whether supplementation with lutein can interact with the serum levels of other dietary carotenoids, retinol, and ␣-tocopherol. METHODS. Forty-five subjects received daily supplements of lutein (containing 5% zeaxanthin) for 6 months and were followed up for another 6 months after supplementation. Blood was collected at various intervals and lutein, zeaxanthin, and their metabolites in the sera were quantified by normalphase high-performance liquid chromatography (HPLC)-UV/ visible detection. Other dietary carotenoids, retinol, and ␣-tocopherol were identified and quantified on a C 18 reversed phase HPLC column. RESULTS. After 6 months of supplementation with 10 mg of lutein, the increases in the mean serum levels from baseline were: 210 to 1000 nM/L (P Ͻ 0.0001) for lutein and 56 to 95 nM/L (P Ͻ 0.0001) for zeaxanthin. Similarly, the mean concentrations (nM/L) of carotenoid metabolites increased from 49 to 98 (P Ͻ 0.0001) for 3-hydroxy-␤,-caroten-3Ј-one (3Ј-oxolutein); 31 to 80 (P Ͻ 0.0001) for 3Ј-hydroxy-,-caroten-3-one; and 19 to 25 (P Ͻ 0.0001) for ,-carotene-3,3Ј-dione. The serum levels of these carotenoids gradually decline within 6 months after supplementation. CONCLUSIONS. The increase in the serum levels of lutein/zeaxanthin correlates with increases in the serum levels of their metabolites that have previously been identified in the ocular tissues. Elderly human subjects with and without AMD can safely take supplements of lutein up to 10 mg/d for 6 months with no apparent toxicity or side effects. (Invest Ophthalmol Vis Sci. 2006;47:5234 -5242