14,011 research outputs found

    Topography and mechanical properties of single molecules of type I collagen using atomic force microscopy

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    Although the mechanical behavior of tendon and bone has been studied for decades, there is still relatively little understanding of the molecular basis for their specific properties. Thus, despite consisting structurally of the same type I collagen, bones and tendons have evolved to fulfill quite different functions in living organisms. In an attempt to understand the links between the mechanical properties of these collageneous structures at the macro- and nanoscale, we studied trimeric type I tropocollagen molecules by atomic force microscopy, both topologically and by force spectroscopy. High-resolution imaging demonstrated a mean (± SD) contour length of (287 ± 35) nm and height of (0.21 ± 0.03) nm. Submolecular features, namely the coil-pitch of the molecule, were also observed, appearing as a repeat pattern along the length of the molecule, with a length of ~8 nm that is comparable to the theoretical value. Using force spectroscopy, we established the stretching pattern of the molecule, where both the mechanical response of the molecule and pull-off peak are convoluted in a single feature. By interpreting this response with a wormlike chain model, we extracted the value of the effective contour length of the molecule at (202 ± 5) nm. This value was smaller than that given by direct measurement, suggesting that the entire molecule was not being stretched during the force measurements; this is likely to be related to the absence of covalent binding between probe, sample, and substrate in our experimental procedure

    Science in action: An interdisciplinary science education program

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    Science in Action is an education outreach program for pre-collegiate students. It is based on the concept that, in order to interest students in science, they must see science and scientists at work. The program encompasses the full range of scientific disciplines - the core sciences, engineering, and mathematics. A unique aspect of the program is the involvement and support of scientists and engineers representing local professional societies, industries, business, and academic institutions. An outline of the program is given

    Influence of the geometry on a field-road model : the case of a conical field

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    Field-road models are reaction-diffusion systems which have been recently introduced to account for the effect of a road on propagation phenomena arising in epidemiology and ecology. Such systems consist in coupling a classical Fisher-KPP equation to a line with fast diffusion accounting for a road. A series of works investigate the spreading properties of such systems when the road is a straight line and the field a half-plane. Here, we take interest in the case where the field is a cone. Our main result is that the spreading speed is not influenced by the angle of the cone

    Crop identification using ERTS imagery

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    Digital analysis of August 15 ERTS-I imagery for southeastern South Dakota was performed to determine the feasibility of conducting crop surveys from satellites. Selected areas of bands 4, 5, 6, and 7 positive transparencies were converted to digital form utilizing Signal Analysis and Dissemination Equipment (SADE). The optical transmission values were printed out in a spatial format. Visual analysis of the printouts indicated that cultivated areas were readily distinguished from non-cultivated areas in all four bands. Bare soil was easily recognized in all four bands. Corn and soybeans, the two major crops in the area, were treated as separate classes rather than as a single class called row crops. Bands 6 and 7 provided good results in distinguishing between corn and soybeans

    As Built design specification for CLASSY, an adaptive maximum likelihood clustering method

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    The latest modifications to the CLASSY system and the associate postprocessor MAXLABEL are described. Software and hardware descriptions, control card modifications, and sample executions are given

    As-built design specification for equiprobability ellipses representation of CLASSY clusters

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    There are no author-identified significant results in this report

    Viola pratincola Greene

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    Vitis cinerea Noronha

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