Liquid-immersible electrostatic ultrasonic transducer

A broadband megahertz range electrostatic acoustic transducer for use in a liquid environment is described. A liquid tight enclosure includes a metallic conducting membrane as part of its outside surface and has a means inside the liquid tight enclosure for applying a tension to the membrane and for mounting an electrode such that the flat end of the electrode is aproximately parallel to the membrane. The invention includes structure and a method for ensuring that the membrane and the flat end of the electrode are exactly parallel and a fixed predetermined distance from each other

The role of need for self-expression and arousal to commit university students for environmental responsibility behaviours

University social responsibility as recycling and environmental protection attitude is a core issue in higher education. However, scarce research examines the factors that influence individuals’ commitment to recycling and environmental preservation, and even less explores how that commitment can lead to preferential behavior, word of mouth and willingness to sacrifice for recycling and environmental preservation. This study examines the roles of need for self-expression and arousal to explain commitment and whether commitment leads to those behaviors. The study is duplicated in three countries, each representing different cultural dimensions. Data collected from participants at Universities in South Korea, the United States and Portugal inform a model that supports the majority of the hypotheses and points out some interesting differences in the ways that recycling and environmental preservation should be presented in various cultures to achieve buy-in and behavior change.info:eu-repo/semantics/acceptedVersio

Cataloging Activity Log: Gathering Data To Explain What We Do and What We Need

Slides presented at the Librarians' Association at the University of North Carolina at Chapel Hill Annual Research Forum, May 9, 2013, Chapel Hill, North Carolin

Disciplining Skepticism Through Kant’s Critique, Fichte’s Idealism, and Hegel’s Negations

This chapter considers the encounter of skepticism with the Kantian and post-Kantian philosophical enterprise and focuses on the intriguing feature whereby it is assimilated into this enterprise. In this period, skepticism becomes interchangeable with its other, which helps understand the proliferation of many kinds of views under its name and which forms the background for transforming skepticism into an anonymous, routine practice of raising objections and counter-objections to one’s own view. German philosophers of this era counterpose skepticism to dogmatism and criticism, ancient to modern skepticism, and, importantly, conceptualize the transitions from one form to another, which forms the conceptual matrix in which new disciplinary forms, such as psychology, anthropology, and historicism contend for cultural-intellectual standing beside philosophy. I present this assimilationist trajectory by reviewing three well-known moments of this encounter of skepticism and idealism: (1) Kant’s idealization of skepticism as a floating position amidst various philosophical positions through the dialectic, polemics, systematics, and history of pure reason; (2) Fichte’s schematic conception of skepticism as a dispute of systems in the early Wissenschaftslehre following his review of the skeptic G. E. Schulze’s attacks on Critical philosophy; (3) Hegel’s historicizing conception of skepticism in the context of differences between subjective idealism and speculative thought and his early Jena review of another work by the same skeptic Schulze

Tyrosine Phosphorylation of the UDP-Glucose Dehydrogenase of Escherichia coli Is at the Crossroads of Colanic Acid Synthesis and Polymyxin Resistance

BACKGROUND:In recent years, an idiosyncratic new class of bacterial enzymes, named BY-kinases, has been shown to catalyze protein-tyrosine phosphorylation. These enzymes share no structural and functional similarities with their eukaryotic counterparts and, to date, only few substrates of BY-kinases have been characterized. BY-kinases have been shown to participate in various physiological processes. Nevertheless, we are at a very early stage of defining their importance in the bacterial cell. In Escherichia coli, two BY-kinases, Wzc and Etk, have been characterized biochemically. Wzc has been shown to phosphorylate the UDP-glucose dehydrogenase Ugd in vitro. Not only is Ugd involved in the biosynthesis of extracellular polysaccharides, but also in the production of UDP-4-amino-4-deoxy-L-arabinose, a compound that renders E. coli resistant to cationic antimicrobial peptides. METHODOLOGY/PRINCIPAL FINDINGS:Here, we studied the role of Ugd phosphorylation. We first confirmed in vivo the phosphorylation of Ugd by Wzc and we demonstrated that Ugd is also phosphorylated by Etk, the other BY-kinase identified in E. coli. Tyrosine 71 (Tyr71) was characterized as the Ugd site phosphorylated by both Wzc and Etk. The regulatory role of Tyr71 phosphorylation on Ugd activity was then assessed and Tyr71 mutation was found to prevent Ugd activation by phosphorylation. Further, Ugd phosphorylation by Wzc or Etk was shown to serve distinct physiological purposes. Phosphorylation of Ugd by Wzc was found to participate in the regulation of the amount of the exopolysaccharide colanic acid, whereas Etk-mediated Ugd phosphorylation appeared to participate in the resistance of E. coli to the antibiotic polymyxin. CONCLUSIONS/SIGNIFICANCE:Ugd phosphorylation seems to be at the junction between two distinct biosynthetic pathways, illustrating the regulatory potential of tyrosine phosphorylation in bacterial physiology

Expanding understanding of service exchange and value co-creation: A social construction approach

According to service-dominant logic (S-D logic), all providers are service providers, and service is the fundamental basis of exchange. Value is co-created with customers and assessed on the basis of value-in-context. However, the extensive literature on S-D logic could benefit from paying explicit attention to the fact that both service exchange and value co-creation are influenced by social forces. The aim of this study is to expand understanding of service exchange and value co-creation by complementing these central aspects of S-D logic with key concepts from social construction theories (social structures, social systems, roles, positions, interactions, and reproduction of social structures). The study develops and describes a new framework for understanding how the concepts of service exchange and value co-creation are affected by recognizing that they are embedded in social systems. The study contends that value should be understood as value-in-social-context and that value is a social construction. Value co-creation is shaped by social forces, is reproduced in social structures, and can be asymmetric for the actors involved. Service exchanges are dynamic, and actors learn and change their roles within dynamic service systems

Anharmonicity, Piezoelectricity, and Solid State Nonlinearity

Last summer I showed that for the pure mode directions the nonlinear terms in the equation describing propagation of ultrasound in a crystalline lattice take the same general form as those describing propagation in a fluid.1 This makes possible the definition of a nonlinearity parameter for solids in analogy with the nonlinearity parameter for liquids and gases. The magnitudes of such nonlinearity parameters were shown to be associated with physical properties of the sample under study. Since one can define nonlinearity parameters in terms of linear combinations of second order elastic (SOE) and third order elastic (TOE) constants, it now is possible to go into much more detail. Recent measurements of the TOE constants in diamond lattice solids (cubic symmetry) have been interpreted in terms of the interatomic potential function2 through the use of the Keating model.3Additional measurements have been made in copper single crystals,4 as well as perovskites5 and NaCl which exhibits a very large nonlinearity parameter.6 The research has been expanded to include theoretical work7 and experimental measurements8 for crystals of symmetry other than cubic. Recently the research is devoted to an understanding of the effect of piezoelectricity on nonlinearity measurements.9</p

Overview of the development of nonlinear acoustics

Developments in nonlinear acoustics are followed from gases to liquids to solids. For all materials the nonlinearity parameter can be defined as the negative ratio of the coefficient of the nonlinear term to the coefficient of the linear term in the nonlinear wave equation. With this definition we can compare the nonlinear behaviors of gases, liquids, and solids. However, recent measurements in solids such as rocks and PZT give a much larger nonlinearity parameter. In this case, and similar ones, one must exercise care. Very large nonlinearity parameters often can be explained by inc1uding previously ignored effects in the analysis. As an introduction, the nonlinear behavior of PZT is discussed