Canopy reflectance modeling in a tropical wooded grassland

Geometric/optical canopy reflectance modeling and spatial/spectral pattern recognition is used to study the form and structure of savanna in West Africa. An invertible plant canopy reflectance model is tested for its ability to estimate the amount of woody vegetation from remotely sensed data in areas of sparsely wooded grassland. Dry woodlands and wooded grasslands, commonly referred to as savannas, are important ecologically and economically in Africa, and cover approximately forty percent of the continent by some estimates. The Sahel and Sudan savannas make up the important and sensitive transition zone between the tropical forests and the arid Sahara region. The depletion of woody cover, used for fodder and fuel in these regions, has become a very severe problem for the people living there. LANDSAT Thematic Mapper (TM) data is used to stratify woodland and wooded grassland into areas of relatively homogeneous canopy cover, and then an invertible forest canopy reflectance model is applied to estimate directly the height and spacing of the trees in the stands. Because height and spacing are proportional to biomass in some cases, a successful application of the segmentation/modeling techniques will allow direct estimation of tree biomass, as well as cover density, over significant areas of these valuable and sensitive ecosystems. The model being tested in sites in two different bioclimatic zones in Mali, West Africa, will be used for testing the canopy model. Sudanian zone crop/woodland test sites were located in the Region of Segou, Mali

Improved canopy reflectance modeling and scene inference through improved understanding of scene pattern

The Li-Strahler reflectance model, driven by LANDSAT Thematic Mapper (TM) data, provided regional estimates of tree size and density within 20 percent of sampled values in two bioclimatic zones in West Africa. This model exploits tree geometry in an inversion technique to predict average tree size and density from reflectance data using a few simple parameters measured in the field (spatial pattern, shape, and size distribution of trees) and in the imagery (spectral signatures of scene components). Trees are treated as simply shaped objects, and multispectral reflectance of a pixel is assumed to be related only to the proportions of tree crown, shadow, and understory in the pixel. These, in turn, are a direct function of the number and size of trees, the solar illumination angle, and the spectral signatures of crown, shadow and understory. Given the variance in reflectance from pixel to pixel within a homogeneous area of woodland, caused by the variation in the number and size of trees, the model can be inverted to give estimates of average tree size and density. Because the inversion is sensitive to correct determination of component signatures, predictions are not accurate for small areas

Guided Tissue Remineralization of Resin-Bonded Acid-Etched Dentin

Contemporary biomineralization strategies incorporate non-classical crystallization pathways of fluidic amorphous nanoprecursors and mesoscopic transformation. Using two functional biomimetic molecules, we previously regenerated mineralized dentin from acid-etched dentin using the Guided Tissue Remineralization (GTR) approach, with definitive intrafibrillar remineralization of type-I collagen. Degradation of denuded collagen within dentin adhesive resin-infiltrated dentin is a pertinent problem in dentin bonding. Here, we show that GTR provides a means of salvaging these degrading bonds by remineralizing resin-dentin interfaces. The GTR medium consists of a Portland cement/simulated body fluid that includes polyacrylic acid and polyvinylphosphonic acid biomimetic analogs for amorphous calcium phosphate dimension regulation and collagen targeting. Both interfibrillar and intrafibrillar apatites became readily discernible within the adhesive-bonded dentin after 2-4 months. Amorphous nanoprecursors created by GTR also penetrated the adhesive resin matrix to create nanocomposites. We anticipate GTR to be the starting point for more sophisticated strategies in extending the longevity of resin-dentin bonds

Visuomotor feedback tuning in the absence of visual error information

Large increases in visuomotor feedback gains occur during initial adaptation to novel dynamics, which we propose are due to increased internal model uncertainty. That is, large errors indicate increased uncertainty in our prediction of the environment, increasing feedback gains and co-contraction as a coping mechanism. Our previous work showed distinct patterns of visuomotor feedback gains during abrupt or gradual adaptation to a force field, suggesting two complementary processes: reactive feedback gains increasing with internal model uncertainty and the gradual learning of predictive feedback gains tuned to the environment. Here we further investigate what drives these changes visuomotor feedback gains in learning, by separating the effects of internal model uncertainty from visual error signal through removal of visual error information. Removing visual error information suppresses the visuomotor feedback gains in all conditions, but the pattern of modulation throughout adaptation is unaffected. Moreover, we find increased muscle co-contraction in both abrupt and gradual adaptation protocols, demonstrating that visuomotor feedback responses are independent from the level of co-contraction. Our result suggests that visual feedback benefits motor adaptation tasks through higher visuomotor feedback gains, but when it is not available participants adapt at a similar rate through increased co-contraction. We have demonstrated a direct connection between learning and predictive visuomotor feedback gains, independent from visual error signals. This further supports our hypothesis that internal model uncertainty drives initial increases in feedback gains.Comment: 29 pages, 11 figures. arXiv admin note: substantial text overlap with arXiv:2008.0757

League Parity: Bringing Back Unlicensed Competition in the Sports Fan Apparel Market

Should professional sports teams and collegiate institutions have an exclusive right to merchandise their logos? Recent court decisions have effectively provided these organizations with a monopoly in the fan apparel marketplace, as retailers who are not officially licensed by the underlying team or university are likely to face trademark infringement liability. In some contexts, this extension of trademark law has prevented companies from selling merchandise that merely displays a team\u27s color scheme. However, such a broad prohibition on the use of team logos is inconsistent with the goal of trademark law, which is intended to prohibit uses of a mark only where consumers are likely to be confused as to the source or sponsorship of the underlying product. Importantly, the thrust of this goal is to bring clarity to the marketplace, as consumers use trademarks to quickly gauge a product\u27s quality. To this end, the fan apparel context is unique because consumers do not view team logos as indicators of product quality. Rather, team logos function merely as a way for fans to show support for a given team. Because team logos do not serve to indicate a product\u27s quality, companies should be able to design and sell fan apparel without obtaining authorization from—and paying licensing fees to—the underlying teams. Consumers would benefit greatly from this de-monopolization of the fan apparel marketplace, and they would no longer have to pay a premium to support the teams they love