276 research outputs found

    Effects of Story-by-Story Post-Tensioning on Multi-Story Buildings

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    The effects of story-by-story horizontal post-tensioning (PT) on multi-story buildings are investigated using staged construction analyses. Analytical column-supported and wall-supported multi-story models are studied to represent different degrees of restraint by supports. Findings include a determination that part of the PT force applied to an upper floor slab is diverted to floors below through flexure and shear of vertical structural elements. The first elevated PT floor and a PT roof may experience significantly reduced slab precompression from PT force diversion. Design recommendations are provided. The design of structural frames incorporating post-tensioned concrete members should consider secondary actions, such as moments and shears, for both horizontal and vertical members due to staged PT construction, in addition to gravity and lateral loads. Concrete PT floor slab serviceability stress checks should use realistic slab effective precompression forces, considering diversion of precompression forces through supports, rather than forces in tendons at that floor

    Perancangan Buku Ilustrasi Pengenalan Nama Buah-buahan Dengan Sistem Isyarat Bahasa Indonesia (Sibi) Berbasis Karakter Untuk Anak-anak Tklb-b Karya Mulia Surabaya

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    Interest illustrated book about the introduction of fruits name with a character-based system SIBI for children TKLB-B Karya Mulia Surabaya is as a learning medium that contains the values of science. The study was conducted with qualitative methods based on interviews, observation, documentation, and literature to support the design of a book about the house\u27s name recognition fruits. Data can be analyzed at several stages of data reduction, data presentation, and conclusion. After analyzing the data found informative design concept, the average informative Indonesian big dictionary into said. This concept aims to be informative book designed to provide insight to the public about the introduction of fruits name. Mechanical reality promoted expected to help draft informative because it is interactive, so people can find out the name of the fruit in the dictionary SIBI. Results of design book is expected that children know more about the fruit in the form of illustrated book based characte

    The 'idioglossia' cases of the 1890s and the clinical investigation and treatment of developmental language impairment

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    The early history of developmental language impairment in late 19th century Britain is considered through the critical examination of three papers appearing in 1891 by Hadden, Golding-Bird and Hale White, and Taylor. They represent innovative investigations of child language disorders whose themes and concerns are resonant today. The term ‘idioglossia’ was coined to identify this new impairment and reflected the belief by some that these children spoke an invented language. Rather than viewing these children as having some constitutional deficiency, these 19th century physicians were novel in insisting that children with language impairments merited extensive clinical investigation and treatment. Their case descriptions and the subsequent debates regarding classification and prognosis are reviewed. Further consideration is given to how these cases led to questioning the relation between language and speech and other aspects of child development and disorder. Reflection on the early sources of clinical categories provides a new perspective on our current formulations for variation in developmental language trajectories

    Spin interactions and switching in vertically tunnel-coupled quantum dots

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    We determine the spin exchange coupling J between two electrons located in two vertically tunnel-coupled quantum dots, and its variation when magnetic (B) and electric (E) fields (both in-plane and perpendicular) are applied. We predict a strong decrease of J as the in-plane B field is increased, mainly due to orbital compression. Combined with the Zeeman splitting, this leads to a singlet-triplet crossing, which can be observed as a pronounced jump in the magnetization at in-plane fields of a few Tesla, and perpendicular fields of the order of 10 Tesla for typical self-assembled dots. We use harmonic potentials to model the confining of electrons, and calculate the exchange J using the Heitler-London and Hund-Mulliken technique, including the long-range Coulomb interaction. With our results we provide experimental criteria for the distinction of singlet and triplet states and therefore for microscopic spin measurements. In the case where dots of different sizes are coupled, we present a simple method to switch on and off the spin coupling with exponential sensitivity using an in-plane electric field. Switching the spin coupling is essential for quantum computation using electronic spins as qubits.Comment: 13 pages, 9 figure

    Intraorganizational evolution

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    Intraorganizational evolution (iOE) is a relatively new, emergent area of research. Although evolutionary metaphors have often surfaced in organization theory, attempts to analyze the evolutionary dynamics unfolding within organizations have been quite sparse and systematic only in recent years. The basic concepts and tools of iOE are thus still in the process of being shaped. As a subject of analysis, iOE is the set of processes through which intraorganizational entities of different types (e.g. routines, jobs, formal rules) reproduce and modify themselves, and change their relative frequency in populations of individuals carrying them. As a theoretical perspective, it is the attempt to apply the lens of evolutionary thinking to the observation and understanding of these processes

    The evolutionary paths towards complexity: a metabolic perspective

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    As sessile organisms, land plants have exploited their metabolic systems to produce a panoply of structurally and functionally diverse natural chemicals and polymers to adapt to challenging ecosystems. Many of these core and specialized metabolites confer chemical shields against a multitude of abiotic stresses, while others play important roles in plants' interactions with their biotic environments. Plant specialized metabolites can be viewed as complex traits in the sense that the biosynthesis of these molecules typically requires multistep metabolic pathways comprising numerous specific enzymes belonging to diverse protein fold families. Resolving the evolutionary trajectories underlying the emergence of these specialized metabolic pathways will impact a fundamental question in biology – how do complex traits evolve in a Darwinian fashion? Here, I discuss several general patterns observed in rapidly evolving specialized metabolic systems in plants, and surmise mechanistic features at enzyme, pathway and organismal levels that rationalize the remarkable malleability of these systems through stepwise evolution. Future studies, focused on fine sampling of metabolic enzymes and pathways in phylogenetically related plant species, or employing directed evolution strategies in synthetic systems, will significantly broaden our perspective on how biological complexity arises at the metabolic level.Howard Hughes Medical InstitutePioneer Foundation (Postdoctoral Fellowship

    The contrasting role of male relatedness in different mechanisms of sexual selection in red junglefowl

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    In structured populations, competition for reproductive opportunities should be relaxed among related males. The few tests of this prediction often neglect the fact that sexual selection acts through multiple mechanisms, both before and after mating. We performed experiments to study the role of within-group male relatedness across pre- and postcopulatory mechanisms of sexual selection in social groups of red junglefowl, Gallus gallus, in which two related males and one unrelated male competed over females unrelated to all the males. We confirm theoretical expectations that, after controlling for male social status, competition over mating was reduced among related males. However, this effect was contrasted by other sexual selection mechanisms. First, females biased male mating in favor of the unrelated male, and might also favor his inseminations after mating. Second, males invested more—rather than fewer—sperm in postcopulatory competition with relatives. A number of factors may contribute to explain this counterintuitive pattern of sperm allocation, including trade-offs between male investment in pre- versus postcopulatory competition, differences in the relative relatedness of pre- versus postcopulatory competitors, and female bias in sperm utilization in response to male relatedness. Collectively, these results reveal that within-group male relatedness may have contrasting effects in different mechanisms of sexual selection

    Thorough assessment of DNA preservation from fossil bone and sediments excavated from a late Pleistocenee-Holocene cave deposit on Kangaroo Island, South Australia

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    Fossils and sediments preserved in caves are an excellent source of information for investigating impacts of past environmental changes on biodiversity. Until recently studies have relied on morphology-based palaeontological approaches, but recent advances in molecular analytical methods offer excellent potential for extracting a greater array of biological information from these sites. This study presents a thorough assessment of DNA preservation from late Pleistocene-Holocene vertebrate fossils and sediments from Kelly Hill Cave Kangaroo Island, South Australia. Using a combination of extraction techniques and sequencing technologies, ancient DNA was characterised from over 70 bones and 20 sediment samples from 15 stratigraphic layers ranging in age from >20 ka to ~6.8 ka. A combination of primers targeting marsupial and placental mammals, reptiles and two universal plant primers were used to reveal genetic biodiversity for comparison with the mainland and with the morphological fossil record for Kelly Hill Cave. We demonstrate that Kelly Hill Cave has excellent long-term DNA preservation, back to at least 20 ka. This contrasts with the majority of Australian cave sites thus far explored for ancient DNA preservation, and highlights the great promise Kangaroo Island caves hold for yielding the hitherto-elusive DNA of extinct Australian Pleistocene species

    Bare Bones Pattern Formation: A Core Regulatory Network in Varying Geometries Reproduces Major Features of Vertebrate Limb Development and Evolution

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    BACKGROUND: Major unresolved questions regarding vertebrate limb development concern how the numbers of skeletal elements along the proximodistal (P-D) and anteroposterior (A-P) axes are determined and how the shape of a growing limb affects skeletal element formation. There is currently no generally accepted model for these patterning processes, but recent work on cartilage development (chondrogenesis) indicates that precartilage tissue self-organizes into nodular patterns by cell-molecular circuitry with local auto-activating and lateral inhibitory (LALI) properties. This process is played out in the developing limb in the context of a gradient of fibroblast growth factor (FGF) emanating from the apical ectodermal ridge (AER). RESULTS: We have simulated the behavior of the core chondrogenic mechanism of the developing limb in the presence of an FGF gradient using a novel computational environment that permits simulation of LALI systems in domains of varying shape and size. The model predicts the normal proximodistal pattern of skeletogenesis as well as distal truncations resulting from AER removal. Modifications of the model's parameters corresponding to plausible effects of Hox proteins and formins, and of the reshaping of the model limb, bud yielded simulated phenotypes resembling mutational and experimental variants of the limb. Hypothetical developmental scenarios reproduce skeletal morphologies with features of fossil limbs. CONCLUSIONS: The limb chondrogenic regulatory system operating in the presence of a gradient has an inherent, robust propensity to form limb-like skeletal structures. The bare bones framework can accommodate ancillary gene regulatory networks controlling limb bud shaping and establishment of Hox expression domains. This mechanism accounts for major features of the normal limb pattern and, under variant geometries and different parameter values, those of experimentally manipulated, genetically aberrant and evolutionary early forms, with no requirement for an independent system of positional information
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