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- Cramer, Bradley D., et al.
(författare)
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Testing the limits of Paleozoic chronostratigraphic correlation via high-resolution (<500 k.y.) integrated conodont, graptolite, and carbon isotope (delta C-13(carb)) biochemostratigraphy across the Llandovery-Wenlock (Silurian) boundary: Is a unified Phanerozoic time scale achievable?
- 2010
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Ingår i: Geological Society of America Bulletin. - 0016-7606. ; 122:9-10, s. 1700-1716
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Tidskriftsartikel (refereegranskat)abstract
- The resolution and fidelity of global chronostratigraphic correlation are direct functions of the time period under consideration. By virtue of deep-ocean cores and astrochronology, the Cenozoic and Mesozoic time scales carry error bars of a few thousand years (k.y.) to a few hundred k. y. In contrast, most of the Paleozoic time scale carries error bars of plus or minus a few million years (m. y.), and chronostratigraphic control better than +/- 1 m. y. is considered "high resolution." The general lack of Paleozoic abyssal sediments and paucity of orbitally tuned Paleozoic data series combined with the relative incompleteness of the Paleozoic stratigraphic record have proven historically to be such an obstacle to intercontinental chronostratigraphic correlation that resolving the Paleozoic time scale to the level achieved during the Mesozoic and Cenozoic was viewed as impractical, impossible, or both. Here, we utilize integrated graptolite, conodont, and carbonate carbon isotope (delta C-13 carb) data from three paleocontinents (Baltica, Avalonia, and Laurentia) to demonstrate chronostratigraphic control for upper Llandovery through middle Wenlock (TelychianSheinwoodian, similar to 436-426 Ma) strata with a resolution of a few hundred k.y. The interval surrounding the base of the Wenlock Series can now be correlated globally with precision approaching 100 k.y., but some intervals (e. g., uppermost Telychian and upper Shein-woodian) are either yet to be studied in sufficient detail or do not show sufficient biologic speciation and/or extinction or carbon isotopic features to delineate such small time slices. Although producing such resolution during the Paleozoic presents an array of challenges unique to the era, we have begun to demonstrate that erecting a Paleozoic time scale comparable to that of younger eras is achievable.
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- McKay, James D., et al.
(författare)
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Vitamin D Receptor Polymorphisms and Breast Cancer Risk: Results from the National Cancer Institute Breast and Prostate Cancer Cohort Consortium
- 2009
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Ingår i: Cancer Epidemiology Biomarkers & Prevention. - 1538-7755. ; 18:1, s. 297-305
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Tidskriftsartikel (refereegranskat)abstract
- Background: Vitamin D is hypothesized to lower the risk of breast cancer by inhibiting cell proliferation via the nuclear vitamin D receptor (VDR). Two common single nucleotide polymorphisms (SNP) in the VDR gene (VDR), rs154441.0 (BsmI), and rs2228570 (FokI), have been inconsistently associated with breast cancer risk. Increased risk has been reported for the FokIff genotype, which encodes a less transcriptionally active isoform of VDR, and reduced risk has been reported for the BsmI BB genotype, a SNP in strong linkage disequilibrium with a 3'-untranslated region, which may influence VDR mRNA stability. Methods: We pooled data from 6 prospective studies in the National Cancer Institute Breast and Prostate Cancer Cohort Consortium to examine associations between these SNPs and breast cancer among >6,300 cases and 8,100 controls for each SNP using conditional logistic regression. Results: The odds ratio (OR) for the rs2228570 (FokI) ff versus FF genotype in the overall population was statistically significantly elevated [OR, 1-1.6; 95% confidence interval (95% CI), 1.04-1.28] but was weaker once data from the cohort with previously published positive findings were removed (OR, 1.1.0; 95% CI, 0.981.24). No association was noted between rs1544410 (Bsm I) BB and breast cancer risk overall (OR, 0.98; 95% CI, 0.89-1.09), but the BB genotype was associated with a significantly lower risk of advanced breast cancer (OR, 0.74; 95% CI, 0.60-0.92). Conclusions: Although the evidence for independent contributions of these variants to breast cancer susceptibility remains equivocal, future large studies should integrate genetic variation in VDR with biomarkers of vitamin D status. (Cancer Epidemiol Biomarkers Prev 2009;18(1):297-305)
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- Cramer, Bradley D., et al.
(författare)
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Revised correlation of Silurian Provincial Series of North America with global and regional chronostratigraphic units and delta 13C(carb) chemostratigraphy
- 2011
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Ingår i: Lethaia. - : Scandinavian University Press / Universitetsforlaget AS. - 0024-1164. ; 44:2, s. 185-202
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Forskningsöversikt (refereegranskat)abstract
- Recent revisions to the biostratigraphic and chronostratigraphic assignment of strata from the type area of the Niagaran Provincial Series (a regional chronostratigraphic unit) have demonstrated the need to revise the chronostratigraphic correlation of the Silurian System of North America. Recently, the working group to restudy the base of the Wenlock Series has developed an extremely high-resolution global chronostratigraphy for the Telychian and Sheinwoodian stages by integrating graptolite and conodont biostratigraphy with carbonate carbon isotope (delta 13C(carb)) chemostratigraphy. This improved global chronostratigraphy has required such significant chronostratigraphic revisions to the North American succession that much of the Silurian System in North America is currently in a state of flux and needs further refinement. This report serves as an update of the progress on recalibrating the global chronostratigraphic correlation of North American Provincial Series and Stage boundaries in their type area. The revised North American classification is correlated with global series and stages as well as regional classifications used in the United Kingdom, the East Baltic, Australia, China, the Barrandian, and Altaj. Twenty-four potential stage slices, based primarily on graptolite and conodont zones and correlated to the global series and stages, are illustrated alongside a new composite delta 13C(carb) curve for the Silurian. Conodont, graptolite, isotope, New York, Ontario, series, Silurian, stage.
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- Lawler, M. J., et al.
(författare)
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New Insights Into the Composition and Origins of Ultrafine Aerosol in the Summertime High Arctic
- 2021
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Ingår i: Geophysical Research Letters. - 0094-8276 .- 1944-8007. ; 48:21
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Tidskriftsartikel (refereegranskat)abstract
- The summertime high Arctic atmosphere is characterized by extremely low aerosol abundance, such that small natural aerosol inputs have a strong influence on cloud formation and surface temperature. The physical sources and the mechanisms responsible for aerosol formation and development in this climate-critical and changing region are still uncertain. We report time-resolved measurements of high Arctic Aitken mode (∼20–60 nm diameter) aerosol composition during August–September 2018. During a significant Aitken mode formation event, the particles were composed of a combination of primary and secondary materials. These results highlight the importance of primary aerosol sources for high Arctic cloud formation, and they imply the action of a poorly understood atmospheric mechanism separating larger particles into multiple sub-particles.
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- Saltzman, Katarina, 1966, et al.
(författare)
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Gardeners’ perspectives and practices in relation to plants in motion
- 2021
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Ingår i: Routledge Handbook of Biosecurity and Invasive Species. - Abingdon, Oxon ; New York, NY : Routledge, 2021. : Routledge. - 9780815354895 ; , s. 226-239
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Bokkapitel (refereegranskat)abstract
- The establishment of introduced species in new environments is today widely acknowledged as a potential threat to biodiversity, and many plants that are known to be invasive have obviously spread from gardens. Thus, in the context of biosecurity, we need to consider how contemporary gardeners think about which plants and animals are welcome in their gardens. In this chapter we look at vegetation in motion from a cultural and social point of view, with a particular focus on some of many different ways in which people are involved in spreading of plants, both desired and undesired ones. We do this by investigating everyday practices of gardeners in Sweden, and not least the common habit of sharing plants, in order to highlight the social and cultural aspects of the spread of species. Among the gardeners in this study it is obvious that the dynamics and vitality of plants is often regarded as an asset, but also sometimes as problem, when plants simply grow too much. Understandings of the relationship between gardens and surrounding environments, as well as between nature and culture, have changed over time, and are continuously changing. As plants have the ability to multiply and spread in various ways, both on their own and with the help of humans, there is a need to acknowledge the role of human as well as non-human agencies in order to understand the complexity of these interactions. Inspired by Tim Ingold we find it useful to think about both gardeners and plants as ‘biosocial becomings’. In order to address the threat posed by invasive species, we propose that it is important to improve our understanding of what happens in everyday biosocial encounters between people, plants and other species.
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