Conventions for the analysis of spherical arrays

The equations and the notation for the analysis of arrays of discrete elements located on the surface of a sphere axe derived and discussed. Methods are also given for finding the coordinates of the far field points needed to calculate the antenna pattern that would be observed in a plane chosen to pass through the main beam. Such patterns would be observed if a spherical array were mounted on the usual antenna turntables currently available.     

Role of visual imprinting in the emergence of specific filial attachments in ducklings.

Conducted 2 experiments with a total of 36 1-11 day old Khaki Campbell ducklings, to assess the suppression of distress vocalization by 2 distinctive stimuli before and after Ss were imprinted to 1 of the stimuli. In Exp. I, both stimuli strongly suppressed distress calls initially. At 5 days of age, however, only the stimulus involved in imprinting suppressed the calls. Results suggest that the loss of control by the nonimprinted stimulus was age-related and represented the development of fear to insufficiently-familiar stimuli. In Exp. II, 5-11 day old Ss were permitted lengthy exposure to a novel imprinting-type stimulus. Under these circumstances, distress vocalization eventually came under stimulus control. The overall pattern of results suggests that through imprinting, stimuli that innately evoke filial behavior become familiar and thus are prevented from later evoking novelty-induced fear. (16 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Design of maximum thrust plug nozzles with variable inlet geometry

An optimization analysis is presented for axisymmetric plug nozzles with varible inlet geometry. The analysis is based on the governing gas dynamic relations for a rotational flow of a frozen or equilibrium gas mixture. The problem is formulated to maximize the axial thrust produced by the plug nozzle for a general isoperimetric constraint, such as constant nozzle length or constant nozzle surface area. The effects of base pressure and ambient pressure are included in the thrust expression to be maximized. The governing gas dynamic equations and the differential and integral constraints that the solution must satisfy are incorporated into the formulation by means of Lagrange multiples. The formalism of the calculus of variations is applied to the resulting functional to be maximized. The results of the optimization analysis are a set of partial differential equations for determining the Lagrange multipliers in the region of interest and a set of equations for determining the necessary boundary conditions for the solution. The complete set of equations for the gas dynamic properties and the Lagrange multipliers are system of first order, quasi-linear, non-homogeneous partial differential equations of the hyperbolic type, which can be treated by the method of charac- teristics. The characteristic and compatibility equations for the system are presented. A numerical solution procedure is presented to determine wether or not a given plug nozzle geometry is an optimal solution. An iteration technique is developed which systematically adjusts the plug nozzle geometry until the optimal solution is obtained. Selected parametric studies are presented. These studies illustrate the effect of the specific heat ratio, the design pressure ratio and the base pressure model on the thrust peformance and nozzle geometry of optimal, fixed length, plug nozzles.     

Methods for determining stability in continuum elastic-rod models of DNA

Elastic-rod models of DNA have offered an alternative method for studying the macroscopic properties of the molecule. An essential component of the modelling effort is to identify the biologically accessible, or stable, solutions. The underlying variational structure of the elastic-rod model can be exploited to derive methods that identify stable equilibrium configurations. We present two methods for determining the stability of the equilibria of elastic-rod models: the conjugate-point method and the distinguished-diagram method. Additionally, we apply these methods to two intrinsically curved DNA molecules: a DNA filament with an A-tract bend and a DNA minicircle with a catabolite gene activator protein binding site. The stable solutions of these models provide visual insight into the three-dimensional structure of the DNA molecules.     

Summary of US–Japan Exchange 2004: New Directions and Physics for Compact Toroids

Scientists from research institutions in the United States of America and Japan attended a USA Department of Energy sponsored joint international workshop on the subject of Compact Toroids (CT) in Santa Fe, NM, USA in September 2004. We outline here a summary of the topics that were discussed, some of the implications, and new directions that are likely to follow from this research. Experimental, theoretical and computational results were presented. The experimental devices and concepts, along with the theory and computational models comprise investigations of fundamental plasma physics, fusion science, and approaches to fusion energy that require magnetized plasmas.     

The philosophical underpinnings of peer review.

The current impetus for peer review had its origin in issues of cost containment, bolstered by intentions to improve quality of service. Peer review is usually conceived of as a way to either police a profession by ridding it of the few "bad actors" or to assure that services delivered meet minimum standards. The present article argues, however, that a more useful philosophy of peer review is to assume that it is at the heart of the definition of a profession. (2 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)