361 research outputs found

    Tightening the thread from seed to cloth. New enquiries in the archaeology of Old World cotton

    Get PDF
    « Un homme qui passe remarque un arbuste dont les branches se terminent par des flocons blancs. On peut imaginer qu’il approche la main. L’espĂšce humaine vient de faire connaissance avec la douceur du coton. »« Pour comprendre les mondialisations, celles d’hier et celle d’aujourd’hui, rien ne vaut l’examen d’un morceau de tissu. Sans doute parce qu’il n’est fait que de fils et de liens, et des voyages de la navette. »Erik Orsenna 2006 – Voyage au pays du coton, 11-12, 17 Introduction In these..

    Pego do Diabo (Loures, Portugal): Dating the Emergence of Anatomical Modernity in Westernmost Eurasia

    Get PDF
    Neandertals and the Middle Paleolithic persisted in the Iberian Peninsula south of the Ebro drainage system for several millennia beyond their assimilation/replacement elsewhere in Europe. As only modern humans are associated with the later stages of the Aurignacian, the duration of this persistence pattern can be assessed via the dating of diagnostic occurrences of such stages

    Use of remote-sensing reflectance to constrain a data assimilating marine biogeochemical model of the Great Barrier Reef

    Get PDF
    Skillful marine biogeochemical (BGC) models are required to understand a range of coastal and global phenomena such as changes in nitrogen and carbon cycles. The refinement of BGC models through the assimilation of variables calculated from observed in-water inherent optical properties (IOPs), such as phytoplankton absorption, is problematic. Empirically derived relationships between IOPs and variables such as chlorophyll-a concentration (Chl a), total suspended solids (TSS) and coloured dissolved organic matter (CDOM) have been shown to have errors that can exceed 100% of the observed quantity. These errors are greatest in shallow coastal regions, such as the Great Barrier Reef (GBR), due to the additional signal from bottom reflectance. Rather than assimilate quantities calculated using IOP algorithms, this study demonstrates the advantages of assimilating quantities calculated directly from the less error-prone satellite remote-sensing reflectance (RSR). To assimilate the observed RSR, we use an in-water optical model to produce an equivalent simulated RSR and calculate the mismatch between the observed and simulated quantities to constrain the BGC model with a deterministic ensemble Kalman filter (DEnKF). The traditional assumption that simulated surface Chl a is equivalent to the remotely sensed OC3M estimate of Chl a resulted in a forecast error of approximately 75 %. We show this error can be halved by instead using simulated RSR to constrain the model via the assimilation system. When the analysis and forecast fields from the RSR-based assimilation system are compared with the non-assimilating model, a comparison against independent in situ observations of Chl a, TSS and dissolved inorganic nutrients (NO3, NH4 and DIP) showed that errors are reduced by up to 90 %. In all cases, the assimilation system improves the simulation compared to the non-assimilating model. Our approach allows for the incorporation of vast quantities of remote-sensing observations that have in the past been discarded due to shallow water and/or artefacts introduced by terrestrially derived TSS and CDOM or the lack of a calibrated regional IOP algorithm

    Galaxy and Mass Assembly (GAMA): halo formation times and halo assembly bias on the cosmic web

    Get PDF
    We present evidence for halo assembly bias as a function of geometric environment (GE). By classifying Galaxy and Mass Assembly (GAMA) galaxy groups as residing in voids, sheets, filaments or knots using a tidal tensor method, we find that low-mass haloes that reside in knots are older than haloes of the same mass that reside in voids. This result provides direct support to theories that link strong halo tidal interactions with halo assembly times. The trend with GE is reversed at large halo mass, with haloes in knots being younger than haloes of the same mass in voids. We find a clear signal of halo downsizing – more massive haloes host galaxies that assembled their stars earlier. This overall trend holds independently of GE. We support our analysis with an in-depth exploration of the L-Galaxies semi-analytic model, used here to correlate several galaxy properties with three different definitions of halo formation time. We find a complex relationship between halo formation time and galaxy properties, with significant scatter. We confirm that stellar mass to halo mass ratio, specific star formation rate (SFR) and mass-weighed age are reasonable proxies of halo formation time, especially at low halo masses. Instantaneous SFR is a poor indicator at all halo masses. Using the same semi-analytic model, we create mock spectral observations using complex star formation and chemical enrichment histories, which approximately mimic GAMA’s typical signal-to-noise ratio and wavelength range. We use these mocks to assert how well potential proxies of halo formation time may be recovered from GAMA-like spectroscopic data

    De dubbele waterput uit het laat-Romeinse castellum van Oudenburg (prov. West-Vlaanderen): tafonomie, chronologie en interpretatie

    Get PDF
    This article focuses on a remarkable well structure that was brought to light by the Flemish Heritage Institute during recent archaeological research at the south-western corner of the Saxon Shore fort at Oudenburg (2001-2005). The site of Oudenburg is situated 8 km from the Flemish coastline, in the polder area between Bruges and Ostend. During Roman times however, positioned strategically on an elevated sandy ridge, the site overlooked the coastal plain consisting of mudflats and marshes intersected by natural gullies. The remains of the fort at Oudenburg were discovered in 1956-1957 by J. Mertenslater excavation campaigns in 1960 and 1970 on the western defence area revealed a sequence of three successive forts. The 1960s excavations on two late Roman military cemeteries more than 400 m to the west of the castellum revealed burials of 4th-century fort inhabitants with rich grave goods. During archaeological research within the fort walls in 1976-1977 the first information was collected about the inner organisation of the fort and the remains of a stone building of late 3rd-century date were excavated. It was only in 2001 that new excavations could take place on the fort area. This systematic research resulted in a finer chronology for the occupation of the castellum. A succession of five main fort periods was revealed, dating between ca. 200 and the beginning of the 5th century AD. These excavations yielded insight into the spatial organisation of the south west area of the fort, which had different functions in each successive fort period. The first three phases belonged to wood and earthen fortstemporary installations in times of trouble and Germanic threat. Probably in the later 3rd century AD, a more permanent fort measuring 153 by 176 m was built in stonethis was renovated and reoccupied during the second quarter of the 4th century AD. The characteristics of the ground plan, its topographical position and several finds pointing to a close link with the Saxon Shore forts on the coast of south Britannia, suggest that Oudenburg was probably part of the Litus Saxonicum. In this paper the so-called double well, a context of the fifth fort period (4th centurybeginning 5th century), is analysed. During this period the south-western area of the castellum was dominated by a stone bath building with hypocaust system. Later in the 4th century, long fences were constructed to divide the area into yards, a timber-framed construction with simple plan may be identified as a stable structure, and a large oak basin was probably a reservoir for drinking water. The double well, which received feature number OS 2562, seems to be a key context for this fort period

    Longitudinal evaluation of aflatoxin exposure in two cohorts in south-western Uganda

    Get PDF
    Aflatoxins (AF) are a group of mycotoxins. AF exposure causes acute and chronic adverse health effects such as aflatoxicosis and hepatocellular carcinoma in human populations, especially in the developing world. In this study, AF exposure was evaluated using archived serum samples from human immunodeficiency virus (HIV)-seronegative participants from two cohort studies in south-western Uganda. AFB1-lysine (AFB-Lys) adduct levels were determined via HPLC fluorescence in a total of 713 serum samples from the General Population Cohort (GPC), covering eight time periods between 1989 and 2010. Overall, 90% (642/713) of the samples were positive for AFB-Lys and the median level was 1.58 pg mg(-1) albumin (range = 0.40-168 pg mg(-1) albumin). AFB-Lys adduct levels were also measured in a total of 374 serum samples from the Rakai Community Cohort Study (RCCS), across four time periods between 1999 and 2003. The averaged detection rate was 92.5% (346/374) and the median level was 1.18 pg mg(-1) albumin (range = 0.40-122.5 pg mg(-1) albumin). In the GPC study there were no statistically significant differences between demographic parameters, such as age, sex and level of education, and levels of serum AFB-Lys adduct. In the RCCS study, longitudinal analysis using generalised estimating equations revealed significant differences between the adduct levels and residential areas (p = 0.05) and occupations (p = 0.02). This study indicates that AF exposure in people in two populations in south-western Uganda is persistent and has not significantly changed over time. Data from one study, but not the other, indicated that agriculture workers and rural area residents had more AF exposure than those non-agricultural workers and non-rural area residents. These results suggest the need for further study of AF-induced human adverse health effects, especially the predominant diseases in the region

    Hundreds of variants clustered in genomic loci and biological pathways affect human height

    Get PDF
    Most common human traits and diseases have a polygenic pattern of inheritance: DNA sequence variants at many genetic loci influence the phenotype. Genome-wide association (GWA) studies have identified more than 600 variants associated with human traits, but these typically explain small fractions of phenotypic variation, raising questions about the use of further studies. Here, using 183,727 individuals, we show that hundreds of genetic variants, in at least 180 loci, influence adult height, a highly heritable and classic polygenic trait. The large number of loci reveals patterns with important implications for genetic studies of common human diseases and traits. First, the 180 loci are not random, but instead are enriched for genes that are connected in biological pathways (P = 0.016) and that underlie skeletal growth defects (P < 0.001). Second, the likely causal gene is often located near the most strongly associated variant: in 13 of 21 loci containing a known skeletal growth gene, that gene was closest to the associated variant. Third, at least 19 loci have multiple independently associated variants, suggesting that allelic heterogeneity is a frequent feature of polygenic traits, that comprehensive explorations of already-discovered loci should discover additional variants and that an appreciable fraction of associated loci may have been identified. Fourth, associated variants are enriched for likely functional effects on genes, being over-represented among variants that alter amino-acid structure of proteins and expression levels of nearby genes. Our data explain approximately 10% of the phenotypic variation in height, and we estimate that unidentified common variants of similar effect sizes would increase this figure to approximately 16% of phenotypic variation (approximately 20% of heritable variation). Although additional approaches are needed to dissect the genetic architecture of polygenic human traits fully, our findings indicate that GWA studies can identify large numbers of loci that implicate biologically relevant genes and pathways.
    • 

    corecore