An improved perturbation approach to the 2D Edwards polymer -- corrections to scaling

We present the results of a new perturbation calculation in polymer statistics which starts from a ground state that already correctly predicts the long chain length behaviour of the mean square end--to--end distance $\langle R_N^2 \rangle\$, namely the solution to the 2~dimensional~(2D) Edwards model. The $\langle R_N^2 \rangle$ thus calculated is shown to be convergent in $N$, the number of steps in the chain, in contrast to previous methods which start from the free random walk solution. This allows us to calculate a new value for the leading correction--to--scaling exponent~$\Delta$. Writing $\langle R_N^2 \rangle = AN^{2\nu}(1+BN^{-\Delta} + CN^{-1}+...)$, where $\nu = 3/4$ in 2D, our result shows that $\Delta = 1/2$. This value is also supported by an analysis of 2D self--avoiding walks on the {\em continuum}.Comment: 17 Pages of Revtex. No figures. Submitted to J. Phys.

Designing an effective evaluation model for the South African Department of Agriculture

Governments are under increasing pressure to deliver results. Therefore, it is important to evaluate the effectiveness, efficiency and relevance of the public service in implementing policies and programmes for social betterment. Without such evaluations, it is difficult to ensure that evidence is integrated into policy and used in practice due to lack of generalizability and learning. This paper focuses on (1) the knowledge that is relevant to understand evaluation influence, (2) the possible conceptual frameworks that enable understanding of the evaluation implementation process, (3) possible models of the process of organizational evaluation, and (4) the main ways of intervening to increase influence. The context for analysis is the South African Department of Agriculture.Evaluation, Evaluation Influence, Policy, Programmes, South Africa, Political Economy, Research Methods/ Statistical Methods,

Magnetic control assembly qualification model

Fabrication and testing of the magnetic control assembly (MCA) are summarized. The MCA was designed as an add-on unit for certain existing components of the Nimbus and ERTS attitude control system. The MCA system consists of three orthogonal electromagnets; a magnetometer probe capable of sensing external fields in the X, Y, and Z axes; and the control electronics. An operational description of the system is given along with all major drawings and photographs. Manufacturing and inspection procedures are outlined and a chronological list of events is included with the fabrication summary

Meta-evaluations in government and government institutions: A case study example from the Australian Centre for International Agricultural Research

In this paper we draw on impact assessment work of the Australian Centre for International Agricultural Research (ACIAR) to present an example of meta-evaluation – an evaluation of evaluations – in an agricultural research, development and extension setting. We explore quality issues relating to evaluation studies in the context of government institutions. Program evaluation standards (PES) are divided into categories of utility, feasibility, propriety and accuracy to provide a framework for the meta-evaluation. The PES are presented as a universal measure of evaluation study quality. The intent of using them here is to judge the adequacy of PES as a universal quality measure or meta-evaluation base and to extract useful insights from ACIAR program evaluation activities when developing a meta-evaluation model for the Limpopo Department of Agriculture (LDA). Our meta-evaluation is undertaken of 63 impact assessment reports. First, the literature guiding the conduct of a meta-evaluation is reviewed. Second, an assessment (the meta-evaluation) of the evaluation studies is carried out for 19 sampled reports from a population of relevant reports fitting the dimension of the analysis, and results are presented and discussed. Also, lessons learned are presented, using the framework provided by the meta-evaluation criteria. Third, taking into account the lessons learned, implications are drawn for a proposed systematic meta-evaluation of the LDA. Finally, we conclude that all the PES cannot be equally emphasized in a meta-evaluation model. At ACIAR, 70% of the standards were at least partially addressed. Therefore, we succeeded in using the PES in judging the ACIAR evaluation quality. As such, they can be an important base when developing an evaluation model but should be applied in a contextualized manner.Meta-evaluation, Evaluation Quality, Program Evaluation Standards, Evaluation Model, Australian Centre for International Agricultural Research, Limpopo Department of Agriculture (South Africa), International Development,

The solar dynamic radiator with a historical perspective

A historical perspective on pumped-fluid loop space radiators provides a basis for the design of the Space Station Solar Dynamic (SD) power module radiator. SD power modules, capable of generating 25 kW (electrical) each, are planned for growth in Station power requirements. The Brayton cycle SD module configuration incorporates a pumped-fluid loop radiator that must reject up to 99 kW (thermal). The thermal/hydraulic design conditions in combination with required radiator orientation and packaging envelope form a unique set of constraints as compared to previous pumped-fluid loop radiator systems. Nevertheless, past program successes have demonstrated a technology base that can be applied to the SD radiator development program to ensure a low risk, low cost system

A Mechanism for Ferrimagnetism and Incommensurability in One-Dimensional Systems

A mechanism for ferrimagnetism in (1+1)-dimensions is discussed. The ferrimagnetism is cased by interactions described by operators with non-zero conformal spin. Such interactions appear in such problems as the problem of tunneling between Luttinger liquids and the problem of frustrated spin ladder. I present exact solutions for a representative class of models containing such interactions together with a simple mean field analysis. It is shown that the interactions (i) dynamically generate static oscillations with a wave vector dependent on the coupling constant, (ii) give rise to a finite magnetic moment at $T = 0$ accompanied by the soft mode with a non-relativistic ({\it ferromagnetic}) dispersion $E \sim k^2$, (iii) generate massive (roton) modes.Comment: replaced by the extended version, references adde

Photoproduction of h_c

Using the NRQCD factorization formalism, we calculate the total cross section for the photoproduction of h_c mesons. We include color-octet and color-singlet mechanisms as well as next-to-leading order perturbative QCD corrections. The theoretical prediction depends on two nonperturbative matrix elements that are not well determined from existing data on charmonium production. For reasonable values of these matrix elements, the cross section is large enough that the h_c may be observable at the E831 experiment and at the HERA experiments.Comment: Revtex file 8 pages, 1 figure. Macros needed: epsf,floats,rotate Minor typos changed, and reference added. Version to be published in Phys.Rev.

CHARACTERISTICS OF DIFFERENT CONSUMER SEGMENTS IN THE AUSTRALIAN BEEF MARKET

Beef consumers in Australia have shown differences in their preferences for products and sensitivity to price. This can be explained by the influence on expected quality of cues related to health, production process and eating experience. Eating experience is difficult to predict as consumers generally do not have enough information to form reliable expectations. In this context, branded beef can help to signal quality and reduce the degree of uncertainty that consumers experience when shopping. Focus group research identified different segments, premiums for preferred products and potential for large-scale differentiation and branding in the Australian market.Beef Branding, Consumer Preferences, Segmentation, Focus Groups.,