Is there a fifth international radiocarbon intercomparison (VIRI)?

The issue of comparability of measurements (and thus bias, accuracy, and precision of measurement) from diverse laboratories is one which has been the focus of some attention both within the radiocarbon community and the wider user communities. As a result, the C-14 community has undertaken a widescale, far-reaching, and evolving program of inter- comparisons, to the benefit of laboratories and users alike. The benefit to the users is, however, indirect, since the C-14 intercomparisons have not been used to generate "league tables" of performance, but rather to allow individual laboratories to check procedures and modify them as required. The historical progression of C-14 laboratory intercomparisons from the Third (TIRI, completed in 1995, Gulliksen and Scott 1995) and Fourth (FIRI, completed in 2000, Scott 2003; Boaretto et al. 2000; Bryant et al. 2002) suggests that a Fifth (VIRI) should also be expected. We describe the plans for VIRI

A practice-led approach to facial animation research

In facial expression research, it is well established that certain emotional expressions are universally recognized. Studies into the observer perception of dynamic expressions have built upon this research by highlighting the importance of particular facial regions, timings, and temporal configurations to perception and interpretation. In many studies, the stimuli for such studies have been generated through posing by non-experts or performances by trained actors. However, skilled character animators are capable of crafting recognizable, believable emotional facial expressions as a part of their professional practice. ‘Emotional Avatars’ was conceived as an interdisciplinary research project which would draw upon the knowledge of animation practice and emotional psychology. The aim of the project was to jointly investigate the artistic generation and observer perception of emotional expression animation to determine whether the nuances of emotional facial expression could be artistically choreographed to enhance audience interpretation

Mice lacking C1q or C3 show accelerated rejection of minor H disparate skin grafts and resistance to induction of tolerance

Complement activation is known to have deleterious effects on organ transplantation. On the other hand, the complement system is also known to have an important role in regulating immune responses. The balance between these two opposing effects is critical in the context of transplantation. Here, we report that female mice deficient in C1q (C1qa(−/−)) or C3 (C3(−/−)) reject male syngeneic grafts (HY incompatible) at an accelerated rate compared with WT mice. Intranasal HY peptide administration, which induces tolerance to syngeneic male grafts in WT mice, fails to induce tolerance in C1qa(−/−) or C3(−/−) mice. The rejection of the male grafts correlated with the presence of HY D(b)Uty-specific CD8(+) T cells. Consistent with this, peptide-treated C1qa(−/−) and C3(−/−) female mice rejecting male grafts exhibited more antigen-specific CD8(+)IFN-γ(+) and CD8(+)IL-10(+) cells compared with WT females. This suggests that accumulation of IFN-γ- and IL-10-producing T cells may play a key role in mediating the ongoing inflammatory process and graft rejection. Interestingly, within the tolerized male skin grafts of peptide-treated WT mice, IFN-γ, C1q and C3 mRNA levels were higher compared to control female grafts. These results suggest that C1q and C3 facilitate the induction of intranasal tolerance

¹⁴C AMS at SUERC: improving QA data from the 5 MV tandem AMS and 250 kV SSAMS

In 2003, a National Electrostatics Corporation (NEC) 5MV tandem accelerator mass spectrometer was installed at SUERC, providing the radiocarbon laboratory with 14C measurements to 4–5‰ repeatability. In 2007, a 250kV single-stage accelerator mass spectrometer (SSAMS) was added to provide additional 14C capability and is now the preferred system for 14C analysis. Changes to the technology and to our operations are evident in our copious quality assurance data: typically, we now use the 134-position MC-SNICS source, which is filled to capacity. Measurement of standards shows that spectrometer running without the complication of on-line δ13C evaluation is a good operational compromise. Currently, 3‰ 14C/13C measurements are routinely achieved for samples up to nearly 3 half-lives old by consistent sample preparation and an automated data acquisition algorithm with sample random access for measurement repeats. Background and known-age standard data are presented for the period 2003–2008 for the 5MV system and 2007–2008 for the SSAMS, to demonstrate the improvements in data quality

Is comparability of C-14 dates an issue?: A status report on the fourth international radiocarbon intercomparison

For more than 15 years, the radiocarbon community has participated in a series of laboratory intercomparisons in response to the issue of comparability of measurements as perceived within the wider user communities (Scott et al. 1990; Rozanski et al. 1992; Guiliksen and Scott 1995; Scott et al. 1997).<br/> In this report, we provide an update on the current C-14 laboratory intercomparison and reflect on future issues linked to the laboratory intercomparison program, not least those resulting from a significant growth in the number of accelerator mass spectrometry (AMS) facilities providing routine dating of small samples (milligram size)

A direct comparison of the consequences of plant genotypic and species diversity on communities and ecosystem function

Biodiversity loss is proceeding at an unprecedented rate, yet we lack a thorough understanding of the consequences of losing diversity at different scales. While species diversity is known to impact community and ecosystem processes, genotypic diversity is assumed to have relatively smaller effects. Nonetheless, a few recent studies suggest that genotypic diversity may have quantitatively similar ecological consequences compared to species diversity. Here we show that increasing either genotypic diversity of common evening primrose (Oenothera biennis) or species diversity of old?field plant species resulted in nearly equivalent increases (?17%) in aboveground primary production. The predominant mechanism explaining this effect, niche complementarity, was similar for each type of diversity. Arthropod species richness also increased with both types of plant diversity, but the mechanisms leading to this effect differed: abundance?driven accumulation of arthropod species was important in plant genotypic polycultures, whereas resource specialization was important in plant species polycultures. Thus, similar increases in primary productivity differentially impacted higher trophic levels in response to each type of plant diversity. These results highlight important ecological similarities and differences between genotypic and species diversity and suggest that genotypic diversity may play a larger role in community and ecosystem processes than previously realized.The NSF (DEB- 0950231 to A. A. Agrawal and IGERT small grant in Biogeochemistry and Environmental Biocomplexity to S. H. McArt, S. C. Cook-Patton, and A. L. Parachnowitsch) and USDA-NRI (2006-35302-17431 to J. S. Thaler) supported this wor

Ancient Maya Rural Settlement Patterns, Household Cooperation, and Regional Subsistence Interdependency in the Río Bec Area: Contributions from G-LiHT

Research on intensive agricultural features contributes to the social relations of farming, including the means by which farmers mobilize labor and the possible destination of surplus. Lidar provides high-resolution data on ancient houses and agricultural features at a regional scale. This paper uses lidar data from NASA’s G-LiHT airborne imager to derive insights about rural demography, interhousehold cooperation, and subsistence interdependency among the ancient Maya. We assess the differences in intensity of agricultural investment in rural and urban areas of the Río Bec region of southern Campeche and Quintana Roo, Mexico, leading to inferences about regional food exchange and complex economies. The scale of interconnected ridges and terraces clearly implies interhousehold cooperation, yet this cooperation was not centralized. Rather, we envision a landscape of smallholders who jointly planned the layout and articulation of agricultural features but pooled most of their labor at the level of the household

Complement C3 exacerbates imiquimod-induced skin inflammation and psoriasiform dermatitis

The complement system is pivotal in protection against pathogens, but also plays important roles in bridging innate and adaptive imm une responses (Scott and Botto, 2015) and in modulating local and systemic inflammation (Markiewski and Lambris, 2007). Activation of complement occurs through three different path ways (classical, alte rnative and lectin), converges at C3 cleavage and culminates in the formation of the membrane attack complex. The anaphylotoxic fragments, C3a and C5a, gene rated during the proteolytic cascade, recruit immune cells that can promote the removal of debris and pat hogens, but can also cause tissue damage (Markiewski and Lambris, 2007)

Future needs and requirements for AMS C-14 standards and reference materials

C-14 measurement uses a number of standards and reference materials with different properties. Historically the absolute calibration of C-14 measurement was tied to 1890 wood, through the 'primary' standard of NBS-OxI (produced by the National Bureau of Standards, now NIST - National Institute of Standards and technology) subsequently replaced by NBS-OxII. These are both internationally calibrated and certified materials, whose C-14 activities are known absolutely. A second tier of materials, often called secondary standards or reference materials, and including internationally recognised materials such as ANU-sucrose (now also IAEA-C6), Chinese - sucrose and the IAEA C1-C6 series, augmented by additional oxalic acid samples are also used routinely. The activity of these materials has been estimated from large numbers of measurements made by many laboratories. Recently, further natural materials from the Third and Fourth International Radiocarbon Inter- comparisons (TIRI and FIRI) have been added to this list. The activities of these standards and reference materials span both the applied C-14 age range and the chemical composition range of typical samples, but this is not achieved uniformly and there is a continuing need for reference materials for laboratory quality control and measurement-traceability purposes. In this paper, we review the development of C-14 Standards and reference materials and consider the future requirements for such materials within the C-14 AMS community