Andrew Clifford

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We present the application of a nonparametric method to performing functional principal component analysis for functional curve data that consist of measurements of a random trajectory for a sample of subjects. This design typically consists of an irregular grid of time points on which repeated measurements are taken for a number of subjects. We introduce(More)
Weanling mice were fed an amino acid-based diet supplemented with 0 or 11.3 mumol folic acid/kg diet for approximately 38 days to study behavior and neurochemistry in folate deficiency. After approximately 5 wk, mice fed the unsupplemented diet weighted approximately 70% as much those fed the supplemented diet. After 2 wk, mice fed the unsupplemented diet(More)
In a marker-trait association study we estimated the statistical significance of 65 single nucleotide polymorphisms (SNP) in 23 candidate genes on HDL levels of two independent Caucasian populations. Each population consisted of men and women and their HDL levels were adjusted for gender and body weight. We used a linear regression model. Selected genes(More)
BACKGROUND A quantitative understanding of human folate metabolism is needed. OBJECTIVE The objective was to quantify and interpret human folate metabolism as it might occur in vivo. DESIGN Adults (n = 13) received 0.5 nmol [(14)C]pteroylmonoglutamate (100 nCi radioactivity) plus 79.5 nmol pteroylmonoglutamate in water orally. (14)C was measured in(More)
This noninvasive method for collection and analysis of a wide range of aldehydes and ketones in human breath may enable assessment of lipid peroxidation and metabolic status in vivo. Breath samples are drawn through silica cartridges impregnated with 2,4-dinitrophenylhydrazine, which traps carbonyls as their hydrazone derivatives. The hydrazone derivatives(More)
Solid-phase extraction permits the parallel processing of samples in large numbers. We have applied this technique to the isolation of retinol isotopomers from plasma of humans participating in a study of vitamin A stable isotope dilution. The isotopomers were analyzed by gas chromatography/mass spectrometry. The extraction involves the separation of(More)
Isotope tracer studies, particularly radiocarbon measurements, play a key role in biological, nutritional, and environmental research. Accelerator mass spectrometry (AMS) is now the most sensitive detection method for 14 C, but AMS is not widely used in kinetic studies of humans. Part of the reason is the expense, but costs would decrease if AMS were used(More)
The high-throughput Zn reduction method was developed and optimized for various biological/biomedical accelerator mass spectrometry (AMS) applications of mg of C size samples. However, high levels of background carbon from the high-throughput Zn reduction method were not suitable for sub-mg of C size samples in environmental, geochronology, and(More)
Biological and biomedical applications of accelerator mass spectrometry (AMS) use isotope ratio mass spectrometry to quantify minute amounts of long-lived radioisotopes such as (14)C. AMS target preparation involves first the oxidation of carbon (in sample of interest) to CO 2 and second the reduction of CO 2 to filamentous, fluffy, fuzzy, or firm(More)
RÉSUMÉ Dans cet article, l'auteur expose les limites d'une approche lexico-sémantique en inter-prétation. À l'aide de la théorie du discours, il identifie certaines compétences nécessai-res à l'interprétation et il propose l'élaboration d'un instrument d'évaluation basé sur la rigueur technique apportée à d'autres professions. L'auteur démontre également(More)