2,933 research outputs found

    Characteristics of Ten Tropical Hardwoods from Certified Forests in Bolivia Part I Weathering Characteristics and Dimensional Change

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    Ten tropical hardwoods from Bolivia were evaluated for weathering performance (erosion rate, dimensional stability, warping, surface checking, and splitting). The wood species were Amburana cearensis (roble), Anadenanthera macrocarpa (curupau), Aspidosperma cylindrocarpon (jichituriqui), Astronium urundeuva (cuchi), Caesalpinia cf. pluviosa (momoqui), Diplotropis purpurea (sucupira), Guibourtia chodatiana (sirari), Phyllostylon rhamnoides (cuta), Schinopsis cf. quebracho-colorado (soto), and Tabebuia spp. (lapacho group) (tajibo or ipe). Eucalyptus marginata (jarrah) from Australia and Tectona grandis (teak), both naturally grown from Burma and plantation-grown from Central America, were included in the study for comparison. The dimensional change for the species from Bolivia, commensurate with a change in relative humidity (RH) from 30% to 90%, varied from about 1.6% and 2.0% (radial and tangential directions) for Amburana cearensis to 2.2% and 4.1% (radial and tangential) for Anadenanthera macrocarpa. The dimensional change for teak was 1.3% and 2.5% (radial and tangential) for the same change in relative humidity. None of the Bolivian species was completely free of warp or surface checks; however, Anadenanthera macrocarpa, Aspidosperma cylindrocarpon, and Schinopsis cf. quebracho-colorado performed almost as well as teak. The erosion rate of several of the wood species was considerably slower than that of teak, and there was little correlation between wood density and erosion rate. Part 2 of this report will include information on the decay resistance (natural durability) of these species

    Erosion Rates of Wood During Natural Weathering. Part II. Earlywood and Latewood Erosion Rates

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    This is the second in a series of reports on the erosion rates of wood exposed outdoors near Madison, Wisconsin. In the work reported here, the erosion rates of earlywood and latewood were determined for smooth-planed vertical-grained lumber for an exposure period of 14 years. The specimens were oriented vertically, facing south; erosion was measured annually for the first 6 years and biannually the remainder of the exposure. Wood species were ponderosa pine, lodgepole pine, Engelmann spruce, western hemlock, and red alder. Large differences were observed between earlywood and latewood erosion rates during weathering. Erosion rates varied from 33 ÎĽm/year for lodgepole pine latewood to 58 ÎĽm/year for western hemlock and red alder earlywood. In general, no practical differences in erosion were observed for different orientations of the specimens on the test fence (vertical or horizontal longitudinal axis). Some specimens showed considerable decay after 10 years of exposure

    Characteristics of Ten Tropical Hardwoods from Certified Forests in Bolivia. Part II. Natural Durability to Decay Fungi

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    The natural durability of 10 lesser known, commercially available Bolivian hardwoods to decay fungi was evaluated using a modified ASTM soil-block analysis for 12 weeks. The blocks were then retested for an additional 12 weeks to determine their level of decay resistance, as determined by percentage of weight loss. Astronium urundeuva, Caesalpinia cf. pluviosa, Schinopsis quebrachocolorado, and Tabebuia sp. (Iapacho group) were found to be highly resistant to decay; Amburana cearensis, Anadenanthera colubrina (syn: A. macrocarpa), Aspidosperma cylindrocarpon, Diplotropis purpurea, and Guibourtia chodatiana, resistant to decay; and Phyllostylon rhamnoides, moderately resistant to decay. We conclude that an extended soil-bottle test is an effective tool for assessing the level of natural durability of these and other tropical species

    Detecting a Currency's Dominance or Dependence using Foreign Exchange Network Trees

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    In a system containing a large number of interacting stochastic processes, there will typically be many non-zero correlation coefficients. This makes it difficult to either visualize the system's inter-dependencies, or identify its dominant elements. Such a situation arises in Foreign Exchange (FX) which is the world's biggest market. Here we develop a network analysis of these correlations using Minimum Spanning Trees (MSTs). We show that not only do the MSTs provide a meaningful representation of the global FX dynamics, but they also enable one to determine momentarily dominant and dependent currencies. We find that information about a country's geographical ties emerges from the raw exchange-rate data. Most importantly from a trading perspective, we discuss how to infer which currencies are `in play' during a particular period of time

    A Strategic Vision for Telemedicine and Medical Informatics in Space Flight

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63255/1/15305620050503924.pd

    Impact of Unexpected Events, Shocking News and Rumours on Foreign Exchange Market Dynamics

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    We analyze the dynamical response of the world's financial community to various types of unexpected events, including the 9/11 terrorist attacks as they unfolded on a minute-by-minute basis. We find that there are various 'species' of news, characterized by how quickly the news get absorbed, how much meaning and importance is assigned to it by the community, and what subsequent actions are then taken. For example, the response to the unfolding events of 9/11 shows a gradual collective understanding of what was happening, rather than an immediate realization. For news items which are not simple economic statements, and hence whose implications are not immediately obvious, we uncover periods of collective discovery during which collective opinions seem to oscillate in a remarkably synchronized way. In the case of a rumour, our findings also provide a concrete example of contagion in inter-connected communities. Practical applications of this work include the possibility of producing selective newsfeeds for specific communities, based on their likely impact
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