Iowa State University

About: Iowa State University is a education organization based out in Ames, Iowa, United States. It is known for research contribution in the topics: Population & Gene. The organization has 50151 authors who have published 107716 publications receiving 3355909 citations. The organization is also known as: Iowa State University of Science and Technology & Iowa State College.

The Physical Nature of the Chemical Bond

Abstract: The quantum mechanical wave functions of molecules are discussed. An attempt is made to effect a simultaneous regional and physical partitioning of the molecular density, the molecular pair density, and the molecular energy, in such a way that meaningful concepts can be associated with the density and energy fragments thus formed. The origin of chemical binding is interpreted in terms of the concepts formulated in the partitioning process. (T.F.H.)

Is it time to pull the plug on the hostile versus instrumental aggression dichotomy

Abstract: Psychologists have often categorized human aggression as hostile or instrumental. Hostile aggression is "hot," impulsive behavior that is motivated by a desire to hurt someone; instrumental aggression is "cold," premeditated behavior used as a means to some other end. This dichotomy was useful to the early development of aggression theories and continues to capture important features of nonhuman aggression, but it has outlived its usefulness as a descriptor of fundamentally different kinds of human aggression. It is confounded with the automatic-controlled information-processing dichotomy, and it fails to consider aggressive acts with multiple motives. Knowledge structure models of aggression easily handle these problems. Taking extreme measures to preserve the hostile-instrumental dichotomy will delay further advances in understanding and controlling human aggression. Therefore, this seems a proper time to "pull the plug" and allow the hostile-instrumental aggression dichotomy a dignified death. Language: en

Computational Models for Turbulent Reacting Flows

Abstract: This book presents the current state of the art in computational models for turbulent reacting flows, and analyzes carefully the strengths and weaknesses of the various techniques described The focus is on formulation of practical models as opposed to numerical issues arising from their solution A theoretical framework based on the one-point, one-time joint probability density function (PDF) is developed It is shown that all commonly employed models for turbulent reacting flows can be formulated in terms of the joint PDF of the chemical species and enthalpy Models based on direct closures for the chemical source term as well as transported PDF methods are covered in detail An introduction to the theory of turbulent and turbulent scalar transport is provided for completeness The book is aimed at chemical, mechanical, and aerospace engineers in academia and industry, as well as developers of computational fluid dynamics codes for reacting flows

Agent-based computational economics : A constructive approach to economic theory

Abstract: Economies are complicated systems encompassing micro behaviors, interaction patterns, and global regularities. Whether partial or general in scope, studies of economic systems must consider how to handle difficult real-world aspects such as asymmetric information, imperfect competition, strategic interaction, collective learning, and the possibility of multiple equilibria. Recent advances in analytical and computational tools are permitting new approaches to the quantitative study of these aspects. One such approach is Agent-based Computational Economics (ACE) , the computational study of economic processes modeled as dynamic systems of interacting agents. This chapter explores the potential advantages and disadvantages of ACE for the study of economic systems. General points are concretely illustrated using an ACE model of a two-sector decentralized market economy. Six issues are highlighted: Constructive understanding of production, pricing, and trade processes; the essential primacy of survival; strategic rivalry and market power; behavioral uncertainty and learning; the role of conventions and organizations; and the complex interactions among structural attributes, institutional arrangements, and behavioral dispositions.

Simultaneous Negative Phase and Group Velocity of Light in a Metamaterial

Abstract: We investigated the propagation of femtosecond laser pulses through a metamaterial that has a negative index of refraction for wavelengths around 1.5 micrometers. From the interference fringes of a Michelson interferometer with and without the sample, we directly inferred the phase time delay. From the pulse-envelope shift, we determined the group time delay. In a spectral region, phase and group velocity are negative simultaneously. This means that both the carrier wave and the pulse envelope peak of the output pulse appear at the rear side of the sample before their input pulse counterparts have entered the front side of the sample.