University of Arkansas

About: University of Arkansas is a education organization based out in Fayetteville, Arkansas, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 17225 authors who have published 33329 publications receiving 941102 citations. The organization is also known as: Arkansas & UA.

Directional image transmission sheet and method of making same

Abstract: There is disclosed a partially transparent, directional viewing sheet formed of plastic material with lenses, preferably lenticular lenses, formed on both the front and the back surfaces of the sheet, there being on at least one of the surfaces intervening spaces between the lenses which spaces are not fully transparent and may be imprinted with an image that is viewable through the sheet from some directions. Preferably such lenses separated by non-transparent intervening spaces are concave lenses with a radius of curvature which is less than the radius of curvature of convex lenses, on the other surface, causing the concave lens focal length to be less than, typically about one-half of, the focal length of the convex lenses. The thickness of the sheet and hence the spacing between each concave lens and a corresponding convex lens causes the lenses axial spacing to be about the difference in focal lengths of the lenses producing the effect of a tiny Galilean telescope. The view through such a sheet in a direction substantially aligned with the optical axis of the tiny telescope is a minimally distorted view of objects distant from or near to the opposite side of the sheet while off-axis viewing will present the image imprinted on the intervening spaces between the concave lenses on the back surface of the sheet. Alternative embodiments employ intrusive mask elements between concave lens elements facilitating use for directional control of solar energy while maintaining image transmission for one direction of viewing.

An introduction to tile-based self-assembly and a survey of recent results

Abstract: We first give an introduction to the field of tile-based self-assembly, focusing primarily on theoretical models and their algorithmic nature. We start with a description of Winfree’s abstract Tile Assembly Model (aTAM) and survey a series of results in that model, discussing topics such as the shapes which can be built and the computations which can be performed, among many others. Next, we introduce the more experimentally realistic kinetic Tile Assembly Model (kTAM) and provide an overview of kTAM results, focusing especially on the kTAM’s ability to model errors and several results targeted at preventing and correcting errors. We then describe the 2-Handed Assembly Model (2HAM), which allows entire assemblies to combine with each other in pairs (as opposed to the restriction of single-tile addition in the aTAM and kTAM) and doesn’t require a specified seed. We give overviews of a series of 2HAM results, which tend to make use of geometric techniques not applicable in the aTAM. Finally, we discuss and define a wide array of more recently developed models and discuss their various tradeoffs in comparison to the previous models and to each other.

Interseismic Plate coupling and strain partitioning in the Northeastern Caribbean

Abstract: SUMMARY The northeastern Caribbean provides a natural laboratory to investigate strain partitioning, its causes and its consequences on the stress regime and tectonic evolution of a subduction plate boundary. Here, we use GPS and earthquake slip vector data to produce a present-day kinematic model that accounts for secular block rotation and elastic strain accumulation, with variable interplate coupling, on active faults. We confirm that the oblique convergence between Caribbean and North America in Hispaniola is partitioned between plate boundary parallel motion on the Septentrional and Enriquillo faults in the overriding plate and plateboundary normal motion at the plate interface on the Northern Hispaniola Fault. To the east, the Caribbean/North America plate motion is accommodated by oblique slip on the faults bounding the Puerto Rico block to the north (Puerto Rico subduction) and to the south (Muertos thrust), with no evidence for partitioning. The spatial correlation between interplate coupling, strain partitioning and the subduction of buoyant oceanic asperities suggests that the latter enhance the transfer of interplate shear stresses to the overriding plate, facilitating strike-slip faulting in the overriding plate. The model slip rate deficit, together with the dates of large historical earthquakes, indicates the potential for a large (M w7.5 or greater) earthquake on the Septentrional fault in the Dominican Republic. Similarly, the Enriquillo fault in Haiti is currently capable of a M w7.2 earthquake if the entire elastic strain accumulated since the last major earthquake was released in a single event today. The model results show that the Puerto Rico/Lesser Antilles subduction thrust is only partially coupled, meaning that the plate interface is accumulating elastic strain at rates slower than the total plate motion. This does not preclude the existence of isolated locked patches accumulating elastic strain to be released in future earthquakes, but whose location and geometry are not resolvable with the present data distribution. Slip deficit on faults from this study are used in a companion paper to calculate interseismic stress loading and, together with stress changes due to historical earthquakes, derive the recent stress evolution in the NE Caribbean.

Development and Applications of Portable Biosensors

Abstract: The significance of microfluidics-based and microelectromechanical systems-based biosensors has been widely acknowledged, and many reviews have explored their potential applications in clinical diagnostics, personalized medicine, global health, drug discovery, food safety, and forensics. Because health care costs are increasing, there is an increasing need to remotely monitor the health condition of patients by point-of-care-testing. The demand for biosensors for detection of biological warfare agents has increased, and research is focused on ways of producing small portable devices that would allow fast, accurate, and on-site detection. In the past decade, the demand for rapid and accurate on-site detection of plant disease diagnosis has increased due to emerging pathogens with resistance to pesticides, increased human mobility, and regulations limiting the application of toxic chemicals to prevent spread of diseases. The portability of biosensors for on-site diagnosis is limited due to various issues, including sample preparation techniques, fluid-handling techniques, the limited lifetime of biological reagents, device packaging, integrating electronics for data collection/analysis, and the requirement of external accessories and power. Many microfluidic, electronic, and biological design strategies, such as handling liquids in biosensors without pumps/valves, the application of droplet-based microfluidics, paper-based microfluidic devices, and wireless networking capabilities for data transmission, are being explored.

Does the Voluntary Adoption of Corporate Governance Mechanisms Improve Environmental Risk Disclosures? Evidence from Greenhouse Gas Emission Accounting

Abstract: Prior research suggests that voluntary environmental governance mechanisms operate to manage a firm’s reputation as opposed to being a driver of proactive environmental performance activities In understanding how such corporate governance mechanisms can operate as a symbolic practice, we investigate whether environmental corporate governance characteristics are associated with voluntary environmental disclosure We examine an increasingly important attribute of a firm’s disclosure setting, namely the disclosure of greenhouse gas (GHG) accounting information GHG information represents proprietary non-financial information about the firm’s exposure to environmental concerns and is related to the firm’s operations and future profitability Thus, we expect governance participants would view such information as a potentially important strategic device for managing stakeholder impressions regarding environmental risks We find that the presence of an environmental committee and a chief sustainability officer (CSO) is positively associated with the likelihood of GHG disclosure and that CSO’s are associated with increased disclosure transparency Further analysis reveals that the likelihood of disclosure is associated with committee size, number of committee meetings, expertise of committee members and CSO, and overlap between the environmental committee and audit committee Only expertise of the environmental committee members and the CSO are associated with GHG disclosure transparency, while larger committees tend to be associated with lower transparency Our results are particularly important to those with interests in evaluating the potential role that corporate governance mechanisms play in responding to stakeholder concerns about environmental risks Directors and officers who are considering appointment to similar governance positions, may wish to consider what attributes would make such governance positions more influential