38 research outputs found

    Statistically reinforced machine learning for nonlinear patterns and variable interactions

    Get PDF
    Most statistical models assume linearity and few variable interactions, even though real‐world ecological patterns often result from nonlinear and highly interactive processes. We here introduce a set of novel empirical modeling techniques which can address this mismatch: statistically reinforced machine learning. We demonstrate the behaviors of three techniques (conditional inference tree, model‐based tree, and permutation‐based random forest) by analyzing an artificially generated example dataset that contains patterns based on nonlinearity and variable interactions. The results show the potential of statistically reinforced machine learning algorithms to detect nonlinear relationships and higher‐order interactions. Estimation reliability for any technique, however, depended on sample size. The applications of statistically reinforced machine learning approaches would be particularly beneficial for investigating (1) novel patterns for which shapes cannot be assumed a priori, (2) higher‐order interactions which are often overlooked in parametric statistics, (3) context dependency where patterns change depending on other conditions, (4) significance and effect sizes of variables while taking nonlinearity and variable interactions into account, and (5) a hypothesis using parametric statistics after identifying patterns using statistically reinforced machine learning techniques

    Ordovician rocks of the Rhinns of Galloway

    Get PDF

    Salt Tectonics and Basement Fractures: Key Controls of Recent Sediment Distribution on the Balearic Rise, Western Mediterranean

    No full text
    52 pages, 19 figures, 7 tables, appendixThe Balearic Rise is a morphologically and structurally complex feature on the southern margin of the Balearic Platform, in the western Mediterranean. Originating as a foundered block in Late Miocene time, the rise has acquired a sedimentologically diverse cover of Plio-Quaternary sediments. A study by means of high-resolution reflection profiling (3.5 kHz) and gravity/piston cores emphasizes the effects of a variety of sedimentary processes and of structural controls in the genesis of these Plio-Quaternary sequences. During this geologically recent time interval the Menorca Canyon-Valley-Fan system has exerted an important influence on the sedimentary development of this marginal feature.On the basis of the 3.5kHz profiles, eight categories of acoustic response of the seafloor and shallow subbottom sediments have been defined and can be linked to distinctive sub-environments of the rise that are characterized by specific sedimentary and structural attributes. Abrupt variations in thickness of the Plio-Quaternary sequence attest to the continuing activity of faulting, which has generated a horst-and-graben morphology across most of the rise. More continuous subsidence is evident below the Menorca Fan but even here subrecent fracturing, accompanied by salt-diapirism, has produced a physiographic and sedimentologic complexity which differs significantly from most of the currently accepted submarine fan models.The cored sediments fall into five main types: bioclastic (and terrigenous) sand, silt, turbidite mud, hemipelagic mud, and calcareous ooze. Combinations of these sediment types form three principal associations or sequences: channel sands, turbiditic sequences, and hemipelagic sequences. Four distinct core assemblages are also recognized, on the basis of predominant sediment type and sequence: channel sand assemblage, proximal turbiditic/hemipelagic assemblage, hemipelagic/turbiditic mud assemblage, and basin plain assemblage.Radiocarbon dating of core samples yields average sedimentation rates of 6 to 7 cm per thousand years, the highest rates being encountered on the Balearic Basin plain and in the main Menorca Fan channel while the lowest rates occur in the hemipelagic muds of the elevated regions of the rise. Most of the thick channel sands were deposited between 23,000 and 16,000 years BP, during the last major lowering of sea level.The Menorca Fan differs significantly in physiography and sediment distribution from most other modern submarine fans, mainly because of the reduced importance of overbank flow and channel migration, which results from the activity of shallow fractures and the blocking effects of salt-diapirs, together with the exceptionally coarse grade of material supplied to the fanPeer Reviewe

    Clues of production for the Neolithic Catalhoyuk (central Anatolia) pottery

    No full text
    WOS: 000267559200011Probable source materials and production technologies of neolithic pottery from Catalhoyuk were studied with micromorphological and archaeometrical methods, seeking to shed light on the established techniques and appropriate source material mixtures used by the inhabitants of the epoch (7500 yr BP) in contrast to the reputed idea of primitiveness of the neolithic pottery. The results revealed the use of reed chaff along with mud brick (sun-dried) fragments that may have been derived from brick-making. The application of the 'slip' represents a novel observation and the intention of the use of a dye that needs further confirmation. The presence of gehlenite and aluminum diopside are considered to be the evidence of reached temperatures of about 800 degrees C and not over with short durations manifested by the presence of calcite. Stress phenomena along with the bent weed fragments may also manifest the practice in shaping of pottery, where the former may also reflect fluctuating firing temperatures. Thus, analytical and micromorphological data obtained herein can provide some guidelines on designating prehistoric Anatolian pottery to the archaeologist and potters working on the subject matter

    Fired shards from selected ancient Anatolian ceramics: a brief review of their mineralogical nature and pedological?microstructural evolution

    No full text
    This review is concerned with some key features observed within grouped samples of ancient ceramics that provide important evidence concerning the selection of appropriate raw materials and the evolution of the firing technologies employed in their production. It also demonstrates the importance of distinguishing and accounting for the mineralogical and microstructural attributes and identifying the processes responsible for the microstructural evolution of these ancient ceramics. The mineralogy largely reflects both the nature of the raw materials used and the maximum temperatures achieved during firing, deduced from the presence of specific high temperature minerals (HTMs). The microstructural evolution processes, deduced by the micromorphology of these ancient ceramics and displayed in specific features, observed in both the matrix and the slip of these ceramics, are largely controlled by the firing methods used in manufacturing. Thus, we conclude that the application of micromorphological principles, methods, and observations derived from the broad sphere of ?pedology? to the study of ancient ceramics, provides valuable insights into the independent evolution of ceramic production methods in ancient societies. Thus, most of the observations recorded here concern identification of the raw materials used to make ancient ceramics and the firing processes used in their manufacture. Our data demonstrate that these ancient potters made use of a variety of temper materials (quartz and chaff, together with fragments of locally available rocks and minerals) that are now preserved in the matrix. Furthermore, analyses of the micromorphological attributes displayed by these ancient ceramics are helpful in determining and explaining the shrinkage features (stress coatings or poro-striated b-fabrics) and the preferred orientation of the elongated pores that have developed after firing in poorly controlled and slow-fired furnaces. In this regard, we finally seek to develop a useful data library ultimately targeting the enhancement of simulated ancient ceramic/pottery production, with an overall objective to apply the mineralogical and pedological properties of Anatolian ceramics researched in this work to globally selected shard specimens. Postburial processes, such as the illuviation-deposition of clay minerals to form the observed clay coatings, probably operated during the wet-dry cycles associated with mid-late Holocene climatic fluctuations. Accompanying calcification-decalcification processes, which may result from an intra cramic leaching-deposition of carbonate present in the source material of the pottery, are also consistent with the known wet-dry cycles of the mid to late Holocene pedogenesis (soil formation) episode and is reflected in the clay coatings and further attested by coeval changes in the soil-faunal activity
    corecore