Morphometric Analysis of Dinosaur Tracks from Southwest Arkansas

Dinosaur trackways were discovered in Cretaceous De Queen Limestone strata in Howard County, Arkansas, in June 2011. Multiple trackways with variably sized tridactyl tracks were exposed in a commercial quarry, suggesting multiple theropod species or adult and juvenile tracks of a single species. Results of morphometric analyses of 32 plaster casts from selected trackways are reported in an effort to identify the specific track-making dinosaurs and differentiate large and small tracks. Track measurements included length and width of each track, the lengths and widths of each digit impression, and the angular spread (divarication) between digit impressions. Twenty-nine plaster casts were of tridactyl theropod tracks whereas three casts were of poorly preserved tracks of a presumed but unknown tetradactyl (and possibly tetrapod) organism. Plaster casts of tridactyl theropod tracks ranged from 0.36 to 0.61 m long and 0.22 to 0.54 m wide. The longest digit impression on each track was the second, or middle, digit (range = 0.15 – 0.35 m long) with total digit divarication ranging from 31 - 57 degrees. The Arkansas track measurements were compared to tracks (Eubrontes glenrosensis Shuler 1935) preserved in the correlative Glen Rose Formation, Texas and attributed to the large Early Cretaceous carnosaur, Acrocanthosaurus atokensis. The E. glenrosensis track measurements from Texas plotted within the Arkansas data range, suggesting affinity of the Arkansas tracks to E. glenrosensis. Relatively poor preservation of tetradactyl tracks precluded morphometric analysis, but visual comparison to known Cretaceous crocodilian tracks is suggestive of affinity to such organisms

A Method of Altering Coronal Plane Prosthetic Foot Stiffness for Studying its Effect on Amputee Gait

In an effort to understand the effects of prosthetic foot stiffness on amputee gait and mobility, it is useful to produce prototype prosthetic feet that differ in stiffness. While many commercial prosthetic feet are made out of carbon fiber, the manufacturing process is ill-suited to design experimentation as it is expensive, time consuming and requires tooling modifications to produce design changes. In order to facilitate a study of the effects of coronal plane prosthetic foot stiffness on amputee maneuvering gait, we are manufacturing custom prosthetic feet using a form of additive manufacturing, selective laser sintering (SLS), that was developed at the University of Texas at Austin. We have previously used SLS technology to create functional transtibial prosthetic sockets, ankle-foot orthoses, and prosthetic foot prototypes. To manufacture prosthetic feet with different stiffnesses, we first measured the stiffness profile of a commercially available carbon fiber prosthetic foot on an Instron 3345 (Norwood, MA) in two configurations where the foot was loaded to 114 kg in foot flat at 0° eversion and toe-only at 5° eversion positions. A computer aided design model of an SLS prosthetic foot was developed and adjusted to match the stiffness profile of the carbon fiber foot. Finite element analysis (SolidWorks Corp.; Waltham, MA) was then used to verify that the desired stiffness level was achieved. This process was repeated to create three prosthetic feet with altered coronal plane stiffness profiles (25% greater, 50% greater, and 25% less) while sagittal stiffness was held constant. The prototype feet were fabricated using selective laser sintering in a Vanguard HiQ/HS SLS Machine (3D Systems Corp.; Rock Hill, SC). Finally, the feet were mechanically tested in the same configurations as the carbon fiber foot to confirm that they had the desired stiffness profiles. Prototype feet closely matched the sagittal stiffness of the chosen prosthetic foot while coronal plane stiffnesses were approximately the same, 30% greater and 30% less than the carbon fiber foot. Future work will be to use these feet to observe the influence of coronal plane stiffness on amputee gait

A culture of silence: modes of objectification and the silencing of disabled bodies

Throughout history different practices have attempted to silence the experiences of disabled people. In this paper we explore some of these practices including the medical, familial, and self-subjugating practices English-speaking Canadian polio survivors experienced throughout their lives. We analyze participant’s experiences of silence and silencing through a Foucauldian lens, drawing on the three modes of objectification to explain the institutional and cultural discourses around polio subjects that acted upon and through the polio body to silence it. Participants’ oral history accounts demonstrate how sociocultural and medical practices effectively silenced survivors from speaking about their polio experiences. However, the trope of silence is also uprooted within oral history traditions. We will demonstrate how participants broke their silence and shifted their perspectives on polio and disability, and how this process contributed to their resistance of hegemonic conceptualizations of disability as defective

Energy landscapes, ideal glasses, and their equation of state

Using the inherent structure formalism originally proposed by Stillinger and Weber [Phys. Rev. A 25, 978 (1982)], we generalize the thermodynamics of an energy landscape that has an ideal glass transition and derive the consequences for its equation of state. In doing so, we identify a separation of configurational and vibrational contributions to the pressure that corresponds with simulation studies performed in the inherent structure formalism. We develop an elementary model of landscapes appropriate to simple liquids which is based on the scaling properties of the soft-sphere potential complemented with a mean-field attraction. The resulting equation of state provides an accurate representation of simulation data for the Lennard-Jones fluid, suggesting the usefulness of a landscape-based formulation of supercooled liquid thermodynamics. Finally, we consider the implications of both the general theory and the model with respect to the so-called Sastry density and the ideal glass transition. Our analysis shows that a quantitative connection can be made between properties of the landscape and a simulation-determined Sastry density, and it emphasizes the distinction between an ideal glass transition and a Kauzmann equal-entropy condition.Comment: 11 pages, 3 figure

Translation and Community in the work of Elizabeth Cary

Explores the role of female community within Elizabeth Cary\u27s translations and her play, The Tragedy of Mariam

Molecular structural order and anomalies in liquid silica

The present investigation examines the relationship between structural order, diffusivity anomalies, and density anomalies in liquid silica by means of molecular dynamics simulations. We use previously defined orientational and translational order parameters to quantify local structural order in atomic configurations. Extensive simulations are performed at different state points to measure structural order, diffusivity, and thermodynamic properties. It is found that silica shares many trends recently reported for water [J. R. Errington and P. G. Debenedetti, Nature 409, 318 (2001)]. At intermediate densities, the distribution of local orientational order is bimodal. At fixed temperature, order parameter extrema occur upon compression: a maximum in orientational order followed by a minimum in translational order. Unlike water, however, silica's translational order parameter minimum is broad, and there is no range of thermodynamic conditions where both parameters are strictly coupled. Furthermore, the temperature-density regime where both structural order parameters decrease upon isothermal compression (the structurally anomalous regime) does not encompass the region of diffusivity anomalies, as was the case for water.Comment: 30 pages, 8 figure

Hypoxia increases neutrophil-driven matrix destruction after exposure to Mycobacterium tuberculosis.

The importance of neutrophils in the pathology of tuberculosis (TB) has been recently established. We demonstrated that TB lesions in man are hypoxic, but how neutrophils in hypoxia influence lung tissue damage is unknown. We investigated the effect of hypoxia on neutrophil-derived enzymes and tissue destruction in TB. Human neutrophils were stimulated with M. tuberculosis (M.tb) or conditioned media from M.tb-infected monocytes (CoMTB). Neutrophil matrix metalloproteinase-8/-9 and elastase secretion were analysed by luminex array and gelatin zymography, gene expression by qPCR and cell viability by flow cytometry. Matrix destruction was investigated by confocal microscopy and functional assays and neutrophil extracellular traps (NETs) by fluorescence assay. In hypoxia, neutrophil MMP-8 secretion and gene expression were up-regulated by CoMTB. MMP-9 activity and neutrophil elastase (NE) secretion were also increased in hypoxia. Hypoxia inhibited NET formation and both neutrophil apoptosis and necrosis after direct stimulation by M.tb. Hypoxia increased TB-dependent neutrophil-mediated matrix destruction of Type I collagen, gelatin and elastin, the main structural proteins of the human lung. Dimethyloxalylglycin (DMOG), which stabilizes hypoxia-inducible factor-1α, increased neutrophil MMP-8 and -9 secretion. Hypoxia in our cellular model of TB up-regulated pathways that increase neutrophil secretion of MMPs that are implicated in matrix destruction

Using airborne LiDAR Survey to explore historic-era archaeological landscapes of Montserrat in the eastern Caribbean

This article describes what appears to be the first archaeological application of airborne LiDAR survey to historic-era landscapes in the Caribbean archipelago, on the island of Montserrat. LiDAR is proving invaluable in extending the reach of traditional pedestrian survey into less favorable areas, such as those covered by dense neotropical forest and by ashfall from the past two decades of active eruptions by the Soufrière Hills volcano, and to sites in localities that are inaccessible on account of volcanic dangers. Emphasis is placed on two aspects of the research: first, the importance of ongoing, real-time interaction between the LiDAR analyst and the archaeological team in the field; and second, the advantages of exploiting the full potential of the three-dimensional LiDAR point cloud data for purposes of the visualization of archaeological sites and features

Technological Diffusion, Spatial Spillovers And Regional Convergence In Europe

In this paper we study two closely related issues. First, the role of technology heterogeneity and diffusion in the convergence of GDP per worker observed across the European regions, in the absence of data on regional TFP. Second, the spatial pattern of the observed regional heterogeneity in technology and the relevance of this pattern for the econometric analysis of regional convergence in Europe. As for the first issue, our aim is to assess whether the convergence observed across European regions is due to convergence in technology as well as to convergence in capital-labor ratios. We first develop a growth model where technology accumulation in lagging regions depends on their own propensity to innovate and on technology diffusion from the leading region, and convergence in GDP per worker is due to both capital deepening and catch-up. We use data (1978-97) on 131 European regions. Propensities to innovate are computed by assigning each patent collected by the European Patent Office to its region of origin. Our findings are consistent with the hypothesis that technology differs across regions and that convergence is partly due to technological catch-up. As for the second empirical issue, we study to what extent each region's propensity to innovate is correlated with that of the surrounding regions. Our results show, first, that the performance of each region does depend on that of the surrounding areas. Second, that the intensity of such spillovers fades with distance. Taken together, these findings suggest the existence of significant localized spillovers of technological knowledge. Finally, we show that these spillovers are strong enough to play a role that cannot be ignored in the econometric analysis of the convergence process in Europe

Remaking Africa's informal economies: youth, entrepreneurship and the promise of inclusion at the bottom of the pyramid

In recent years, the quest for 'inclusive markets' that incorporate Africa's youth has become a key focus of national and international development efforts, with so-called bottom of the pyramid (BoP) initiatives increasingly seen as a way to draw the continent's poor into new networks of global capitalism. SSA has become a fertile frontier for such systems, as capital sets its sights on the continents vast 'under-served' informal economies, harnessing the entrepreneurial mettle of youth to create new markets for a range of products, from solar lanterns and shampoo to cook stoves and sanitary pads. Drawing on ethnographic research with youth entrepreneurs, we trace the prcesses of individual and collective 'transformation' that the mission of (self-) empowerment through entrepreneurship seeks to bring about. We argue that, while such systems are meant to bring those below the poverty line above it, the 'line' is reified and reinforced through a range of discursive and strategic practices that actively construct and embed distinctions between the past and the future, valuable and valueless, and the idle and productive in Africa's informal economies