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- Yafa, C., et al.
(author)
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Development of an ombrotrophic peat bog (low ash) reference material for the determination of elemental concentrations
- 2004
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In: Journal of Environmental Monitoring. - : Royal Society of Chemistry (RSC). - 1464-0325 .- 1464-0333. ; 6:493, s. 501-
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Journal article (peer-reviewed)abstract
- Given the increasing interest in using peat bogs as archives of atmospheric metal deposition, the lack of validated sample preparation methods and suitable certified reference materials has hindered not only the quality assurance of the generated analytical data but also the interpretation and comparison of peat core metal profiles from different laboratories in the international community. Reference materials play an important role in the evaluation of the accuracy of analytical results and are essential parts of good laboratory practice. An ombrotrophic peat bog reference material has been developed by 14 laboratories from nine countries in an inter-laboratory comparison between February and October 2002. The material has been characterised for both acid-extractable and total concentrations of a range of elements, including Al, As, Ca, Cd, Cr, Cu, Fe, Hg, Mg, Mn, Na, Ni, P, Pb, Ti, V and Zn. The steps involved in the production of the reference material (i.e. collection and preparation, homogeneity and stability studies, and certification) are described in detail.
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- Cho, E, et al.
(author)
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Dairy foods, calcium, and colorectal cancer : A pooled analysis of 10 cohort studies
- 2004
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In: Journal of the National Cancer Institute. - Harvard Univ, Sch Med, Channing Lab, Boston, MA 02115 USA. Brigham & Womens Hosp, Dept Med, Channing Lab, Boston, MA 02115 USA. Harvard Univ, Sch Publ Hlth, Dept Nutr, Boston, MA 02115 USA. Harvard Univ, Sch Publ Hlth, Dept Epidemiol, Boston, MA 02115 USA. Harvard Univ, Sch Publ Hlth, Dept Biostat, Boston, MA 02115 USA. Loma Linda Univ, Ctr Hlth Res, Sch Med, Loma Linda, CA USA. Maastricht Univ, Dept Epidemiol, Maastricht, Netherlands. Harvard Ctr Canc Prevent, Boston, MA USA. Univ Minnesota, Sch Publ Hlth, Div Epidemiol, Minneapolis, MN 55455 USA. SUNY Buffalo, Dept Social & Prevent Med, Buffalo, NY USA. TNO, Nutr & Food Res Inst, Dept Epidemiol, Zeist, Netherlands. Univ Toronto, Fac Med, Dept Publ Hlth Sci, Toronto, ON, Canada. Natl Publ Hlth Inst, Dept Epidemiol & Hlth Promot, Helsinki, Finland. Fred Hutchinson Canc Res Ctr, Canc Prevent Res Program, Seattle, WA USA. Albert Einstein Coll Med, Dept Epidemiol & Populat Hlth, Bronx, NY 10467 USA. Natl Inst Environm Hlth Sci, Epidemiol Branch, Res Triangle Pk, NC USA. NYU, Dept Obstet Gynecol, Sch Med, New York, NY USA. Natl Inst Environm Med, Div Nutr Epidemiol, Stockholm, Sweden. NYU, Sch Med, Nelson Inst Environm Med & Kaplan Canc Ctr, New York, NY USA. : OXFORD UNIV PRESS INC. - 0027-8874 .- 1460-2105. ; 96:13, s. 1015-1022
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Journal article (peer-reviewed)abstract
- Background. Studies in animals have suggested that calcium may reduce the risk of colorectal cancer. However, results from epidemiologic studies of intake of calcium or dairy foods and colorectal cancer risk have been inconclusive. Methods: We pooled the primary data from 10 cohort studies in five countries that assessed usual dietary intake by using a validated food frequency questionnaire at baseline. For most studies, follow-up was extended beyond that in the original publication. The studies included 534 536 individuals, among whom 4992 incident cases of colorectal cancer were diagnosed between 6 and 16 years of follow-up. Pooled multivariable relative risks for categories of milk intake and quintiles of calcium intake and 95% confidence intervals (CIs) were calculated. All statistical tests were two-sided. Results: Milk intake was related to a reduced risk of colorectal cancer. Compared with the lowest category of intake (<70 g/day), relative risks of colorectal cancer for increasing categories (70-174, 175-249, and greater than or equal to250 g/day) of milk intake were 0.94 (95% CI = 0.86 to 1.02), 0.88 (95% CI = 0.81 to 0.96), and 0.85 (95% CI = 0.78 to 0.94), respectively (P-trend<.001). Calcium intake was also inversely related to the risk of colorectal cancer. The relative risk for the highest versus the lowest quintile of intake was 0.86 (95% CI = 0.78 to 0.95; P-trend = .02) for dietary calcium and 0.78 (95% CI = 0.69 to 0.88; P-trend<.001) for total calcium (combining dietary and supplemental sources). These results were consistent across studies and sex. The inverse association for milk was limited to cancers of the distal colon (P-trend<.001) and rectum (P-trend = .02). Conclusion: Higher consumption of milk and calcium is associated with a lower risk of colorectal cancer.
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- Graham, A.C., et al.
(author)
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0.7 Analogue structures and exchange interactions in quantum wires
- 2004
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In: Solid State Communications. - : Elsevier BV. - 0038-1098 .- 1879-2766. ; 131:9-10 SPEC. ISS., s. 591-597
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Journal article (peer-reviewed)abstract
- We present experimental studies of crossings of spin-split one-dimensional subbands in ballistic quantum wires in an in-plane magnetic field B ?. At low electron densities, a spontaneous spin-splitting occurs as subbands cross, which gives rise to additional non-quantised conductance structures called 0.7 analogues. We analyse the data within a spin-density-functional model, which includes exchange interactions in a magnetic field. Focussing on the region of the crossings of spin-split subbands, it is found that the energy levels rearrange as they cross due to exchange interactions. © 2004 Elsevier Ltd. All rights reserved.
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- Graham, J, et al.
(author)
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Genetic effects on age-dependent onset and islet cell autoantibody markers in type 1 diabetes
- 2002
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In: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 51:5, s. 1346-1355
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Journal article (peer-reviewed)abstract
- Age-dependent associations between type 1 diabetes risk genes HLA, INS VNTR, and CTLA-4 and autoantibodies to GAD65 (GADAs), ICA512/IA-2, insulin, and islet cells were determined by logistic regression analysis in 971 incident patients with type 1 diabetes and 702 control subjects aged 0–34 years. GADAs were associated with HLA-DQ2 in young but not in older patients (P = 0.009). Autoantibodies to insulin were negatively associated with age (P < 0.0001) but positively associated with DQ8 (P = 0.03) and with INS VNTR (P = 0.04), supporting possible immune tolerance induction. ICA512/IA-2 were negatively associated with age (P < 0.0001) and with DQ2 (P < 0.0001) but positively associated with DQ8 (P = 0.04). Males were more likely than females to be negative for GADA (P < 0.0001), autoantibodies to islet cells (P = 0.04), and all four autoantibody markers (P = 0.004). The CTLA-4 3′ end microsatellite marker was not associated with any of the autoantibodies. We conclude that age and genetic factors such as HLA-DQ and INS VNTR need to be combined with islet autoantibody markers when evaluating the risk for type 1 diabetes development.
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- Pagels, A., et al.
(author)
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Millimetre VLBI monitoring of AGN with sub-milliarcsecond resolution
- 2004
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In: in "Proceedings of the 7th European VLBI Network Symposium", Oct. 2004, Toledo, eds. R. Bachiller, F. Colomer, J.F. Desmurs, P. de Vicente, Obs. Astronómico Nacional, Alcala de Henares, Spain. ; , s. 7-10
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Conference paper (other academic/artistic)
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- Starikov, Anton, et al.
(author)
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Effects of accidental microconstriction on the quantized conductance in long wires
- 2003
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In: Proceedings of SPIE, the International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 5023, s. 267-270
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Conference paper (other academic/artistic)abstract
- We have investigated the conductance of long quantum wires formed in GaAs/ AlxGa1-x As heterostructures. Using realistic fluctuation potentials from donor layers we have simulated numerically the conductance of four different kinds of wires. While ideal wires show perfect quantization, potential fluctuations from random donors may give rise to strong conductance oscillations and degradation of the quantization plateaux. Statistically there is always the possibility of having large fluctuations in a sample that may effectively act as a microconstriction. We therefore introduce microconstrictions in the wires by occasional clustering of donors. These microconstrictions are found to restore the quantized plateaux. A similar effect is found for accidental lithographic inaccuracies.
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