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.

Towards reliable bird surveys: accounting for individuals present but not detected

Abstract: COUNTS OF BIRDS seen, heard, or captured are commonly used to elucidate avian-habitat relationships, investigate responses of avian populations to management treatments or to environmental disturbances, estimate spatial distribution of species, and monitor population trends. The point-count method, in which an observer records all birds detected within either a fixed or an unlimited distance from a point during a specified time period (Ferry and Frochot 1970, Hutto et al. 1986), is the most widely used counting method in bird population studies (Ralph et al. 1995, Rosenstock et al. 2002). Point counts and other methods that are based on observed counts to estimate abundance, such as mist netting (Karr 1981), rely on the assumption that numbers of individuals detected (e.g. seen, heard, or captured) represent a constant proportion of actual numbers present across space and time. That is, if the true number of birds within a surveyed area increases by 20% during successive samples, observed counts are assumed to increase by the same percentage. Similarly, counts in different areas during the same time period are assumed to represent the same proportion of birds present within each of those areas. The validity of this proportionality assumption has been questioned for decades (e.g. Burnham 1981) because the many factors affecting detection probabilities of individuals (i.e. probability of correctly identifying the presence of an individual) are neither constant within and among species and habitats nor constant across time (e.g. see Thompson et al. 1998; and Rosenstock et al. 2002 and references therein). Nonetheless, ornithologists continue to rely on survey meth-

Mechanical properties of carbon nanotube/polymer composites

Abstract: The remarkable mechanical properties of carbon nanotubes, such as high elastic modulus and tensile strength, make them the most ideal and promising reinforcements in substantially enhancing the mechanical properties of resulting polymer/carbon nanotube composites. It is acknowledged that the mechanical properties of the composites are significantly influenced by interfacial interactions between nanotubes and polymer matrices. The current challenge of the application of nanotubes in the composites is hence to determine the mechanical properties of the interfacial region, which is critical for improving and manufacturing the nanocomposites. In this work, a new method for evaluating the elastic properties of the interfacial region is developed by examining the fracture behavior of carbon nanotube reinforced poly (methyl methacrylate) (PMMA) matrix composites under tension using molecular dynamics simulations. The effects of the aspect ratio of carbon nanotube reinforcements on the elastic properties, i.e. Young's modulus and yield strength, of the interfacial region and the nanotube/polymer composites are investigated. The feasibility of a three-phase micromechanical model in predicting the elastic properties of the nanocomposites is also developed based on the understanding of the interfacial region.

Legitimation endeavors: Impression management strategies used by an organization in crisis

Abstract: The impression management strategies embedded in the external discourse of an organization in crisis are identified and a typology of impression management strategies used by organizations is developed. Existing documents were used to collect 799 statements dealing with how stakeholders presently viewed or should view the organization. Ingratiation was the primary strategy appearing in the statements, with most ingratiation being self‐enhancing communication. No apologies were present. Different impression management strategies occurred in messages directed to different stakeholders. Intimidation was used with special interest groups. Denouncement strategies were embedded in messages to competitors, special interest groups, and suppliers. Results are discussed in light of institutional theory and the impression management literature.