نتایج جستجو برای: isotope
تعداد نتایج: 32576 فیلتر نتایج به سال:
Oxygen isotope analysis of archaeological skeletal remains is an increasingly popular tool to study past human migrations. It is based on the assumption that human body chemistry preserves the δ18O of precipitation in such a way as to be a useful technique for identifying migrants and, potentially, their homelands. In this study, the first such global survey, we draw on published human tooth en...
Bottled and packaged waters are an increasingly significant component of the human diet. These products are regulated at the regional, national, and international levels, and determining the authenticity of marketing and labeling claims represents a challenge to regulatory agencies. Here, we present a dataset of stable isotope ratios for bottled waters sampled worldwide, and consider potential ...
MILLENNIAL-SCALE CLIMATE VARIABILITY: THE REPLICABILITY OF MARINE RECORDS SHACKLETON, Nicholas J.1, DE ABREU, Lucia2, BLUMBACH, Petya1, CHESHIRE, Heather1, VAUTRAVERS, Maryline2, GRIMALT, Joan3, MARTRAT, Belen4, THOUVENY, Nicolas5, and THOMAS, Lucy6, (1) Godwin Laboratory for Quaternary Studies, Cambridge Univ, Cambridge, CB2 3SA, United Kingdom, [email protected], (2) Godwin Laboratory, Univ of C...
Understanding the ecological patterns of invasive species and their habitats require an understanding of the species' foraging ecology. Stable carbon (δ13C) and nitrogen (δ15N) isotope values provide useful information into the study of animal ecology and evolution, since the isotope ratios of consumers reflect consumer's dietary patterns. Nevertheless, the lack of species- and element-specific...
If A is a unital associative algebra and u is invertible in A, one can define an algebra A, called the u-isotope of A, which is equal to A as a vector space but has a new product x ·u y = xuy. This isotope A (u) is again unital and associative but with a shifted identity element u. More generally there are definitions of isotope for several other classes of unital nonassociative algebras, notab...
Stable isotope ratios are biogeochemical tracers that can be used to determine the source of nutrients and contaminants in avian eggs. However, the interpretation of stable carbon ratios in lipid-rich eggs is complicated because (13)C is depleted in lipids. Variation in (13)C abundance can therefore be obscured by variation in percent lipids. Past attempts to establish an algebraic equation to ...
The purposes of this study were to quantify the impact of the duration of infusion and choice of stable isotope of glucose on measures of glucose rate of appearance (glucose R(a)) and to determine whether the differences observed were due to tracer recycling via the glycogen pool (direct pathway) or gluconeogenesis (indirect pathway). Six healthy adult volunteers were studied on four occasions ...
OBJECTIVES The nature of land use and mobility during the transition to agriculture has often been debated. Here, we use isotope analysis of tooth enamel from human populations buried in two different Neolithic burial monuments, Penywyrlod and Ty Isaf, in south-east Wales, to examine patterns of land use and to evaluate where individuals obtained their childhood diet. MATERIALS AND METHODS We...
Eutrophication is a globally significant challenge facing aquatic ecosystems, associated with human induced enrichment of these ecosystems with nitrogen (N) and phosphorus (P). However, the limited availability of inherent labels for P and N has constrained understanding of the triggers for eutrophication in natural ecosystems and appropriate targeting of management responses. This paper propos...
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