Rethinking cultural hybridity and technology transfer: SEM microstructural analysis of lead glazed ceramics from early colonial Peru

Through Scanning Electron Microscopy (SEM) microstructural analysis, we examine the firing technology of Early Green Glazed (EGG) Ware – a variety of “hybrid” lead-glazed ceramics produced in Peru's north coast region during the 16th century CE. Previous scholars have interpreted EGG Ware as the product of indigenous potters who fired ceramics in kilns and learned how to make glazed vessels through direct instruction from Iberian ceramicists. We argue that the production of EGG Ware entailed a more complex process of technological incorporation and innovation. SEM microstructural analysis of 44 archaeological samples suggests that these ceramics were originally fired under highly variable conditions. Parallel analysis of five samples of lead-glazed ceramics produced in open firings by Peruvian artisans in the 1980's reveals consistent firing beyond their clays' maturation temperatures. Based on these results and analysis of whole EGG Ware vessels from museum collections, we suggest that at least some of our EGG Ware samples were produced in open firings. In turn, we argue that EGG Ware reflects the creativity of native potters who adapted indigenous firing technologies and experimented with different parameters in the process of forging a new decorative tradition

Migraine aura: retracting particle-like waves in weakly susceptible cortex

Cortical spreading depression (SD) has been suggested to underlie migraine aura. Despite a precise match in speed, the spatio-temporal patterns of SD and aura symptoms on the cortical surface ordinarily differ in aspects of size and shape. We show that this mismatch is reconciled by utilizing that both pattern types bifurcate from an instability point of generic reaction-diffusion models. To classify these spatio-temporal pattern we suggest a susceptibility scale having the value [sigma]=1 at the instability point. We predict that human cortex is only weakly susceptible to SD ([sigma]<1), and support this prediction by directly matching visual aura symptoms with anatomical landmarks using fMRI retinotopic mapping. We discuss the increased dynamical repertoire of cortical tissue close to [sigma]=1, in particular, the resulting implications on migraine pharmacology that is hitherto tested in the regime ([sigma]>>1), and potentially silent aura occurring below a second bifurcation point at [sigma]=0 on the susceptible scale

Sherds on the Edge: Characterization of 16th Century Colonial Spanish Pottery Recovered from the Solomon Islands

We present the results of instrumental neutron activation analysis of ceramics recovered from the Solomon Islands, associated with Alvaro de Mendaña y Neira's 16th century colonizing expedition to the region (c.1595-6). Based on the chemical and typological data and previously published petrological and geochronological research, this study assigns the provenance of the ceramics variously to Peru, Panama, Spain, China and Thailand. A comparison of the provenance results with historical records related to Mendaña's voyage also shows the value of the archaeological assemblage in providing a detailed picture of provisioned ceramic types and their provenance

Wet and dry events influenced colonization of a mid-elevation Andean forest

Few paleoecological records are available to document the history of mid-elevation montane forests in the tropical Andes between 1500 and 2500 m above sea level. Archaeological studies have identified late-Holocene human modification of these landscapes, but it is not clear when and to what degree such alteration began. Here, we report fossil pollen, X-ray fluorescence, and charcoal data from Lake Progreso, which lies at 2013 m elevation in the eastern Peruvian Andes. The reconstruction of the effects of climate and human activity on an Andean lower montane forest is the first such high-resolution paleoecological record to span the Holocene. The record begins in the early Holocene, with lake formation in a forested setting that lacked fire. Marked erosive events were recorded in the early and late Holocene, but not the mid-Holocene. The first evidence of human disturbance in the record was the appearance of charcoal c. 6300 cal BP. This onset of burning was followed by maize cultivation c. 4520 cal BP. The basin surrounding Lake Progreso was disturbed and burned by humans intermittently thereafter but retained a predominance of forest throughout its history. The pollen, charcoal, and XRF data suggested that the site was generally used by small groups of people or settled by a small community. The Progreso record bore overall similarities in the timing of human occupation to records from nearby Lake Pomacochas, and the lower elevation site of Lake Sauce, though both those sites showed far greater deforestation. Collectively, these data suggested that Lake Progreso supported much smaller human populations and retained more of its forest than lakes Sauce or Pomacochas. While all sites shared a history of forest burning and maize cultivation, sufficient dissimilarities existed to indicate contrasting histories of site usage. •New data show a long history of human occupation in an Andean cloud forest.•Fires were first set 6300 years ago and maize was grown 4500 years ago.•The human footprint on the forest remained small for thousands of years.•The site was occupied during dry times and probably abandoned during wet ones

Transcription factor Bcl11b controls selection of invariant natural killer T-cells by regulating glycolipid presentation in double-positive thymocytes

Invariant natural killer T cells (iNKT cells) are innate-like T cells important in immune regulation, antimicrobial protection, and anti-tumor responses. They express semi-invariant T cell receptors, which recognize glycolipid antigens. Their positive selection is mediated by double-positive (DP) thymocytes, which present glycolipid self-antigens through the noncanonical MHC class I-like molecule CD1d. Here we provide genetic and biochemical evidence that removal of the transcription factor Bcl11b in DP thymocytes leads to an early block in iNKT cell development, caused by both iNKT cell extrinsic and intrinsic defects. Specifically, Bcl11b-deficient DP thymocytes failed to support Bcl11b-sufficient iNKT precursor development due to defective glycolipid self-antigen presentation, and showed enlarged lysosomes and accumulation of glycosphingolipids. Expression of genes encoding lysosomal proteins with roles in sphingolipid metabolism and glycolipid presentation was found to be altered in Bcl11b-deficient DP thymocytes. These include cathepsins and Niemann–Pick disease type A, B, and C genes. Thus, Bcl11b plays a central role in presentation of glycolipid self-antigens by DP thymocytes, and regulates directly or indirectly expression of lysosomal genes, exerting a critical extrinsic role in development of iNKT lineage, in addition to the intrinsic role in iNKT precursors. These studies demonstrate a unique and previously undescribed role of Bcl11b in DP thymocytes, in addition to the critical function in positive selection of conventional CD4 and CD8 single-positive thymocytes