2,601 research outputs found

    Kütahya-Merkez Balıklı Tekkesi Restorasyon Projesi

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    Why Levallois? A Morphometric Comparison of Experimental ‘Preferential’ Levallois Flakes versus Debitage Flakes

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    Background Middle Palaeolithic stone artefacts referred to as ‘Levallois’ have caused considerable debate regarding issues of technological predetermination, cognition and linguistic capacities in extinct hominins. Their association with both Neanderthals and early modern humans has, in particular, fuelled such debate. Yet, controversy exists regarding the extent of ‘predetermination’ and ‘standardization’ in so-called ‘preferential Levallois flakes’ (PLFs). Methodology/Principal Findings Using an experimental and morphometric approach, we assess the degree of standardization in PLFs compared to the flakes produced during their manufacture. PLFs possess specific properties that unite them robustly as a group or ‘category’ of flake. The properties that do so, relate most strongly to relative flake thicknesses across their surface area. PLFs also exhibit significantly less variability than the flakes generated during their production. Again, this is most evident in flake thickness variables. A further aim of our study was to assess whether the particular PLF attributes identified during our analyses can be related to current knowledge regarding flake functionality and utility. Conclusions/Significance PLFs are standardized in such a manner that they may be considered ‘predetermined’ with regard to a specific set of properties that distinguishes them statistically from a majority of other flakes. Moreover, their attributes can be linked to factors that, based on current knowledge, are desirable features in flake tools (e.g. durability, capacity for retouch, and reduction of torque). As such, our results support the hypothesis that the lengthy, multi-phase, and hierarchically organized process of Levallois reduction was a deliberate, engineered strategy orientated toward specific goals. In turn, our results support suggestions that Levallois knapping relied on a cognitive capacity for long-term working memory. This is consistent with recent evidence suggesting that cognitive distinctions between later Pleistocene hominins such as the Neanderthals and anatomically modern humans were not as sharp as some scholars have previously suggested

    An Assessment of Stone Weapon Tip Standardization During the Clovis-Folsom Transition in the Western United States

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    It has long been assumed that Folsom points are more standardized than Clovis points, although an adequate test of this proposition has yet to be undertaken. Here, we address that deficiency by using data from a sample of Folsom and Clovis points recovered from sites across the western United States. We used geometric morphometric techniques to capture point shape and then conducted statistical analyses of variability associated with Clovis and Folsom point bases and blades. Our results demonstrate that Folsom bases and blades are less variable than those on earlier Clovis points, indicating an increase in point standardization during the Early Paleoindian period. In addition, despite published claims to the contrary, Clovis and Folsom point bases are no more variable than blades. Based on these results, we conducted additional analyses to examine the modularity and size of Clovis and Folsom points. The results suggest Clovis points have more integrated base and blade segments than Folsom points. We suggest that several classes of Clovis points - intended for different functions - might have been in use during the Clovis period and that the later Folsom points might have served only as weapon tips, the shape of which were constrained by the fluting process

    Estimating the Richness of a Population When the Maximum Number of Classes Is Fixed: A Nonparametric Solution to an Archaeological Problem

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    Background: Estimating assemblage species or class richness from samples remains a challenging, but essential, goal. Though a variety of statistical tools for estimating species or class richness have been developed, they are all singly-bounded: assuming only a lower bound of species or classes. Nevertheless there are numerous situations, particularly in the cultural realm, where the maximum number of classes is fixed. For this reason, a new method is needed to estimate richness when both upper and lower bounds are known. Methodology/Principal Findings: Here, we introduce a new method for estimating class richness: doubly-bounded confidence intervals (both lower and upper bounds are known). We specifically illustrate our new method using the Chao1 estimator, rarefaction, and extrapolation, although any estimator of asymptotic richness can be used in our method. Using a case study of Clovis stone tools from the North American Lower Great Lakes region, we demonstrate that singly-bounded richness estimators can yield confidence intervals with upper bound estimates larger than the possible maximum number of classes, while our new method provides estimates that make empirical sense. Conclusions/Significance: Application of the new method for constructing doubly-bound richness estimates of Clovis stone tools permitted conclusions to be drawn that were not otherwise possible with singly-bounded richness estimates, namely, that Lower Great Lakes Clovis Paleoindians utilized a settlement pattern that was probably more logistical in nature than residential. However, our new method is not limited to archaeological applications. It can be applied to any set of data for which there is a fixed maximum number of classes, whether that be site occupancy models, commercial products (e.g. athletic shoes), or census information (e.g. nationality, religion, age, race)

    Determination of the cold storage conditions of some apple cultivars

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    Bu araştırma 2000 2002 yıllan arasında Eğirdir Bahçe Kültürleri Araştırma Enstitüsü ve Süleyman Demirel Üniversitesi Ziraat Fakültesi Bahçe Bitkileri Bölümü Derim Sonrası Fizyoloji Laboratuvarında yürütülmüştür. Çalışmada M9 anacı üzerine aşılı Granny Smith, Imparatore ve Idared elma çeşitlerinin soğukta depolanma koşulları incelenmiştir. Uygun depolama koşulunu belirlemek için iki farklı zamanda derilen elmalar ilk yıl 0 oC ve % 90-95 nispi nem , ikinci yıl -1, 0 ve +2 oC sıcaklık ve yine % 90-95 nispi nem koşullarına sahip üç farklı soğuk odada 6 ay süreyle depolanmışlardır. Depolama boyunca birer ay aralıklarla depodan çıkartılan örneklerde ağırlık kaybı, meyve eti sertliği, suda çözünebilir kuru madde, titre edilebilir asitlik ve renk değerleriyle beraber fizyolojik ve patojen kaynaklı bozulmalar incelenmiştir. Deneme sonuçlarına göre Eğirdir ekolojisinde M9 anacı üzerinde yetiştirilen Granny Smith, Imparatore ve Idared elma çeşitlerinin 0 oC sıcaklık ve % 90-95 nispi nem koşullarında 5-6 ay depolanabileceği saptanmıştır.This research was carried out at Horticulture Research Institute of Egirdir and Postharvest Physiology Lab. of Department of Horticulture, Faculty of Agriculture, University of Süleyman Demirel between 2000 and 20002. Storage conditions of apple varieties Granny Smith, Imparatore and Idared grafted on M9 rootstock were investigated. In order to determine the optimum storage condition, these varieties harvested two different stage were stored at 0 Ctemperature and 90-95%relative humidity in the first year, and at -1, 0 and +2 Cand 90-95% RHin the second year for 6 months. During the storage period, weight loss, fruit flesh firmness, total solible solid, titretable acidity, colorimeter values (L*, a*, b*) and physiological disorders of apples taken from storage by montly intervals were examined.According to the storage results, it is determined that Granny Smith, Imparatore and Idared apple varieties can be stored at 0 Ctemperature and 90-95%relative humidity for 5-6 months

    Early stage blunting causes rapid reductions in stone tool performance

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    Palaeolithic stone technologies have never been investigated in terms of how sharpness influences their ability to cut. In turn, there is little understanding of how quickly stone cutting edges blunt, how past populations responded to any consequent changes in performance, or how these factors influenced the Palaeolithic archaeological record. Presented here is experimental data quantitatively detailing how variation in edge sharpness influences stone tool cutting performance. Significant increases in force (N) and material displacement (mm) requirements occur rapidly within early stages of blunting, with a single abrasive cutting stroke causing, on average, a 38% increase in the force needed to initiate a cut. In energetic terms, this equates to a 70% increase in work (J). Subsequent to early stages of blunting we identify a substantial drop in the impact of additional edge abrasion. We also demonstrate how edge (included) angle significantly influences cutting force and energy requirements and how it co-varies with sharpness. Amongst other conclusions, we suggest that rapid reductions in performance due to blunting may account for the abundance of lithic artefacts at some archaeological sites, the speed that resharpening behaviours altered tool forms, and the lack of microscopic wear traces on many lithic implements

    Recurrent patterns of microdiversity in a temperate coastal marine environment

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    © The Author(s), 2017. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in The ISME Journal 12 (2018): 237–252, doi:10.1038/ismej.2017.165.Temperate coastal marine environments are replete with complex biotic and abiotic interactions that are amplified during spring and summer phytoplankton blooms. During these events, heterotrophic bacterioplankton respond to successional releases of dissolved organic matter as algal cells are lysed. Annual seasonal shifts in the community composition of free-living bacterioplankton follow broadly predictable patterns, but whether similar communities respond each year to bloom disturbance events remains unknown owing to a lack of data sets, employing high-frequency sampling over multiple years. We capture the fine-scale microdiversity of these events with weekly sampling using a high-resolution method to discriminate 16S ribosomal RNA gene amplicons that are >99% identical. Furthermore, we used 2 complete years of data to facilitate identification of recurrent sub-networks of co-varying microbes. We demonstrate that despite inter-annual variation in phytoplankton blooms and despite the dynamism of a coastal–oceanic transition zone, patterns of microdiversity are recurrent during both bloom and non-bloom conditions. Sub-networks of co-occurring microbes identified reveal that correlation structures between community members appear quite stable in a seasonally driven response to oligotrophic and eutrophic conditions.PLB is supported by the European Research Council Advanced Investigator grant ABYSS 294757 to Antje Boetius. AF-G is supported by the European Union’s Horizon 2020 research and innovation program (Blue Growth: Unlocking the potential of Seas and Oceans) under grant agreement no. (634486) (project acronym INMARE). This study was funded by the Max Planck Society. Further support by the Department of Energy Joint Genome Institute (CSP COGITO) and DFG (FOR2406) is acknowledged by HT (TE 813/2-1) and RA (Am 73/9-1)

    Environment-Induced Changes in Selective Constraints on Social Learning During the Peopling of the Americas

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    The weaponry technology associated with Clovis and related Early Paleoindians represents the earliest well-defined evidence of humans in Pleistocene North America. We assess the technological diversity of these fluted stone points found at archaeological sites in the western and eastern halves of North America by employing statistical tools used in the quantification of ecological biodiversity. Our results demonstrate that the earliest hunters in the environmentally heterogeneous East used a more diverse set of points than those in the environmentally homogenous West. This and other evidence shows that environmental heterogeneity in the East promoted the relaxation of selective constraints on social learning and increased experimentation with point designs

    Early Childhood Development in Children Born to HIV-Infected Mothers: Perspectives From Kenyan Clinical Providers and Caregivers

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    Objective. To understand the perspectives of clinical providers and caregivers regarding early childhood development (ECD) in children born to HIV-infected mothers in Kenya. Methods. This was a qualitative study of provider and caregiver perspectives on ECD at 5 Kenyan HIV clinics, using semistructured interviews and focus group discussions. Constant comparison and triangulation methods were employed to elucidate the concepts of ECD. Results. Twenty-five providers and 67 caregivers participated. While providers understood ECD in terms of milestones, caregivers strongly equated ECD with physical growth. Factors affecting ECD, such as nutrition, perinatal effects, and illness, were perceived differently by providers and caregivers. Both groups generally believed that HIV-infected children would have typical ECD if adherent to their HIV treatment. Conclusions. Important considerations regarding ECD in this population were uncovered. Understanding provider and caregiver perspectives’ on ECD in HIV-exposed children is critical for promoting ECD in this community
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