201 research outputs found

    Characterization of the Temporomandibular Joint of Southern Sea Otters (Enhydra lutris nereis).

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    The structure-function relationship of the temporomandibular joint (TMJ) of southern sea otter has largely not been described. This study aims to describe the histological, biochemical, and biomechanical features of the TMJ disk in the southern sea otter. The TMJ disks from fresh cadaver heads of southern sea otter adult males (n = 8) and females (n = 8) acquired from strandings were examined. Following macroscopical evaluation, the TMJs were investigated for their histological, mechanical, and biochemical properties. We found that the sea otter TMJ disks are, in general, similar to other carnivores. Macroscopically, the TMJ disk was highly congruent, and the mandibular head was encased tightly by the mandibular fossa with a thin disk separating the joint into two compartments. Histologically, the articular surfaces were lined with dense fibrous connective tissue that gradually transitioned into one to two cell thick layer of hyaline-like cartilage. The disk fibers were aligned primarily in the rostrocaudal direction and had occasional lacuna with chondrocyte-like cells. The disk was composed primarily of collagen type 1. Biochemical analysis indicates sulfated glycosaminoglycan content lower than other mammals, but significantly higher in male sea otters than female sea otters. Finally, mechanical analysis demonstrated a disk that was not only stronger and stiffer in the rostrocaudal direction than the mediolateral direction but also significantly stronger and stiffer in females than males. We conclude that the congruent design of the TMJ, thin disk, biochemical content, and mechanical properties all reflect a structure-function relationship within the TMJ disk that is likely designed for the sea otter's hard diet and continuous food intake

    Implementasi Algoritma C4.5 Untuk Menentukan Calon Debitur Dengan Mengukur Tingkat Risiko Kredit Pada Bank Bri Cabang Curup

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    Perbankan adalah salah satu sumber dana bagi masyarakat perorangan atau badan USAha untuk memenuhi kebutuhan konsumsinya seperti kebutuhan untuk membeli rumah, mobil atau motor ataupun untuk meningkatkan produksi USAhanya mengingat modal yang dimiliki Perusahaaan ataupun perorangan tidak cukup untuk mendukung peningkatan USAhanya. Risiko perkreditan yang terutama bagi bank adalah bahwa kredit menjadi macet dalam arti bank tidak lagi atau tidak teratur dalam menerima bunga dan angsuran pelunasan kredit. Hal tersebut sangat merugikan pihak bank karena tidak lagi menerima bunga. Algoritma C4.5 bisa digunakan untuk analisa yang dilakukan oleh analis kredit. Penerapan algoritma dalam aplikasi ini bertujuan untuk membuat suatu sistem pendukung keputusan yang dapat memberikan suatu alternatif keputusan bagi para pengambil keputusan dalam menentukan tingkat risiko pemberian kredit

    Solving Tree Problems with Category Theory

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    Artificial Intelligence (AI) has long pursued models, theories, and techniques to imbue machines with human-like general intelligence. Yet even the currently predominant data-driven approaches in AI seem to be lacking humans' unique ability to solve wide ranges of problems. This situation begs the question of the existence of principles that underlie general problem-solving capabilities. We approach this question through the mathematical formulation of analogies across different problems and solutions. We focus in particular on problems that could be represented as tree-like structures. Most importantly, we adopt a category-theoretic approach in formalising tree problems as categories, and in proving the existence of equivalences across apparently unrelated problem domains. We prove the existence of a functor between the category of tree problems and the category of solutions. We also provide a weaker version of the functor by quantifying equivalences of problem categories using a metric on tree problems.Comment: 10 pages, 4 figures, International Conference on Artificial General Intelligence (AGI) 201

    Chemical diffusion of fluorine in melts in the system Na2OAl2O3SiO2

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    The volatilization of fluorine from three melts in the system Na2OAl2O3SiO2 has been investigated at 1 atm pressure and 1200–1400°C. The melts chosen have base compositions corresponding to albite, jadeite and a peraluminous melt with 75 mole % SiO2. Melt spheres were suspended from platinum loops in a vertical tube furnace in a flow of oxygen gas, then quenched, sectioned and analysed by electron microprobe. The microprobe scans indicate that transport of fluorine to the melt-vapor interface is by binary, concentration-independent interdiffusion of fluorine and oxygen. FO interdiffusivity increases in the order albite < peraluminous < jadeite. There is no simple reciprocal relationship between FO interdiffusivity and melt viscosity. Comparison with data on high-pressure interdiffusivity of fluorine and oxygen in jadeite melt indicates that FO interdiffusivity increases with pressure from 0.001 to 10 kbar while the activation energy remains unchanged. Fluorine chemical diffusivity in albite melt is substantially lower than H2O chemical diffusivity in obsidian melts suggesting that different diffusive mechanisms are responsible for the transport of F and H2O in igneous melts. Fluorine diffuses in albite melt via an anionic exchange with oxygen whereas water probably diffuses in obsidian melt via an alkali exchange mechanism

    Categorical Dimensions of Human Odor Descriptor Space Revealed by Non-Negative Matrix Factorization

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    In contrast to most other sensory modalities, the basic perceptual dimensions of olfaction remain unclear. Here, we use non-negative matrix factorization (NMF) – a dimensionality reduction technique – to uncover structure in a panel of odor profiles, with each odor defined as a point in multi-dimensional descriptor space. The properties of NMF are favorable for the analysis of such lexical and perceptual data, and lead to a high-dimensional account of odor space. We further provide evidence that odor dimensions apply categorically. That is, odor space is not occupied homogenously, but rather in a discrete and intrinsically clustered manner. We discuss the potential implications of these results for the neural coding of odors, as well as for developing classifiers on larger datasets that may be useful for predicting perceptual qualities from chemical structures

    Diagnostic Yield of Dental Radiography and Cone-Beam Computed Tomography for the Identification of Anatomic Structures in Cats

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    The objective of this study was to evaluate the diagnostic yield of dental radiography (DR) and 3 cone-beam computed tomography (CBCT) methods for the identification of predefined anatomic structures in cats. For 5 feline cadaver heads and 22 client-owned cats admitted for evaluation and treatment of dental disease, a total of 22 predefined anatomic structures were evaluated separately by use of the DR method and 3 CBCT software modules [multiplanar reconstructions (MPR), tridimensional (3-D) rendering, and reconstructed panoramic views (Pano)]. A semi quantitative scoring system was used, and mean scores were calculated for each anatomic structure and imaging method. The Friedman test was used to evaluate values for significant differences in diagnostic yield. For values that were significant the Wilcoxon signed rank test was used with the Bonferroni-Holm multiple comparison adjustment to determine significant differences among each of the possible pairs of diagnostic methods. Differences of diagnostic yield among the DR and 3 CBCT methods were significant for 17 of 22 anatomic structures. For these structures, DR scores were significantly higher than scores for Pano views for 2 of 17 structures, but DR scores were significantly lower than scores for Pano views for 6 anatomic structures, tridimensional rendering for 10 anatomic structures, and MPR for 17 anatomic structures. In conclusion, it was found that CBCT methods were better suited than DR for the identification of anatomic structures in cats. Results of this study can serve as a basis for CBCT evaluation of dentoalveolar and other maxillofacial bony lesions in cats

    Shear-induced pressure changes and seepage phenomena in a deforming porous layer-I

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    We present a model for flow and seepage in a deforming, shear-dilatant sensitive porous layer that enables estimates of the excess pore fluid pressures and flow rates in both the melt and solid phase to be captured simultaneously as a function of stress rate. Calculations are relevant to crystallizing magma in the solidosity range 0.5–0.8 (50–20 per cent melt), corresponding to a dense region within the solidification front of a crystallizing magma chamber. Composition is expressed only through the viscosity of the fluid phase, making the model generally applicable to a wide range of magma types. A natural scaling emerges that allows results to be presented in non-dimensional form. We show that all length-scales can be expressed as fractions of the layer height H, timescales as fractions of H2(nβ'θ+ 1)/(θk) and pressures as fractions of . Taking as an example the permeability k in the mush of the order of magnitude 1015 m2 Pa1 s1, a layer thickness of tens of metres and a mush strength (θ) in the range 108–1012 Pa, an estimate of the consolidation time for near-incompressible fluids is of the order of 105–109 s. Using mush permeability as a proxy, we show that the greatest maximum excess pore pressures develop consistently in rhyolitic (high-viscosity) magmas at high rates of shear ( , implying that during deformation, the mechanical behaviour of basaltic and rhyolitic magmas will differ. Transport parameters of the granular framework including tortuosity and the ratio of grain size to layer thickness (a/H) will also exert a strong effect on the mechanical behaviour of the layer at a given rate of strain. For dilatant materials under shear, flow of melt into the granular layer is implied. Reduction in excess pore pressure sucks melt into the solidification front at a velocity proportional to the strain rate. For tectonic rates (generally 1014 s1), melt upwelling (or downwelling, if the layer is on the floor of the chamber) is of the order of cm yr1. At higher rates of loading comparable with emplacement of some magmatic intrusions (1010 s1), melt velocities may exceed effects due to instabilities resulting from local changes in density and composition. Such a flow carries particulates with it, and we speculate that these may become trapped in the granular layer depending on their sizes. If on further solidification the segregated grain size distribution of the particulates is frozen in the granular layer, structure formation including layering and grading may result. Finally, as the process settles down to a steady state, the pressure does not continue to decrease. We find no evidence for critical rheological thresholds, and the process is stable until so much shear has been applied that the granular medium fails, but there is no hydraulic failure

    Fatigue evaluation in maintenance and assembly operations by digital human simulation

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    Virtual human techniques have been used a lot in industrial design in order to consider human factors and ergonomics as early as possible. The physical status (the physical capacity of virtual human) has been mostly treated as invariable in the current available human simulation tools, while indeed the physical capacity varies along time in an operation and the change of the physical capacity depends on the history of the work as well. Virtual Human Status is proposed in this paper in order to assess the difficulty of manual handling operations, especially from the physical perspective. The decrease of the physical capacity before and after an operation is used as an index to indicate the work difficulty. The reduction of physical strength is simulated in a theoretical approach on the basis of a fatigue model in which fatigue resistances of different muscle groups were regressed from 24 existing maximum endurance time (MET) models. A framework based on digital human modeling technique is established to realize the comparison of physical status. An assembly case in airplane assembly is simulated and analyzed under the framework. The endurance time and the decrease of the joint moment strengths are simulated. The experimental result in simulated operations under laboratory conditions confirms the feasibility of the theoretical approach
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