Law of Large Numbers for a Class of Superdiffusions

Under spectral conditions, we prove a LLN type result for superdiffusions, where the convergence is meant in probability. The main tool is a space-time H-transformation

Technology Selection and Appropriate Technology

This paper provides a formal model of technology choice by a single region. Case studies have indicated that the technology acquired by LDCs often seem unsuitable, although the criteria for suitability are often unclear. The reasons which are presented for inappropriateness of the selection often rely more on political arguments then economic ones, or treat the recipient country as a passive actor in the whole process. Can a technology actively selected by a recipient country ever by inappropriate, assuming factor cost ratios represent true relative values? A model presented by Evenson and Bingswanger (1978) indicates that a technology developed in one economic or physical environment may be 'appropriate' to a second, very different environment if the second environment can generate a very limited range of technological possibilities on its own. Ranis (1978) has emphasized the importance of information on technological alternatives flowing smoothly and accurately within the system and the need to acquire capacity for adaptive research. Both these approaches recognize the importance of indigenous research capacity, although Ranis accords more emphasis to friction and proper incentives within the system. Barring policy and management problems, their conclusions appear to be that technology choice will be efficient--the appearance of inappropriateness stems from the lack of explicit recognition of the constraints on technology generation in the system. The model presented below builds on the early models of rational technology selection of Evenson- Binswanger and Ranis. It shares common elements with the Evenson-Binswanger model and may be regarded as a generalization of their model. It goes further, however, in several crucial aspects. It allows the extent of both adaptive and independent research to be choice variables in the technology acquisition decision. It allows for selection out of a continuum of technologies which differ in the environments for which they were designed. It allows for limits to the extent to which technologies can be adapted across environments and allows for losses because of incomplete adaption. The public goodnature of research plays a critical role in determining the efficiency of resource allocation as well. The model presented immediately below is couched in terms relating to agricultural technology. A reason for first presenting a model of agricultural technology selection is that many of the conceptual issues possess more intuitive natural interpretations. A second section will consider the impact of market structure on the development of technology, and a third section will broaden the basic model of agricultural technology development to one which encompasses certain types of fixed capital investment. A fourth section discusses testing of the model.Research and Development/Tech Change/Emerging Technologies,

Tuning Monotonic Basin Hopping: Improving the Efficiency of Stochastic Search as Applied to Low-Thrust Trajectory Optimization

Trajectory optimization methods using monotonic basin hopping (MBH) have become well developed during the past decade [1, 2, 3, 4, 5, 6]. An essential component of MBH is a controlled random search through the multi-dimensional space of possible solutions. Historically, the randomness has been generated by drawing random variable (RV)s from a uniform probability distribution. Here, we investigate the generating the randomness by drawing the RVs from Cauchy and Pareto distributions, chosen because of their characteristic long tails. We demonstrate that using Cauchy distributions (as first suggested by J. Englander [3, 6]) significantly improves monotonic basin hopping (MBH) performance, and that Pareto distributions provide even greater improvements. Improved performance is defined in terms of efficiency and robustness. Efficiency is finding better solutions in less time. Robustness is efficiency that is undiminished by (a) the boundary conditions and internal constraints of the optimization problem being solved, and (b) by variations in the parameters of the probability distribution. Robustness is important for achieving performance improvements that are not problem specific. In this work we show that the performance improvements are the result of how these long-tailed distributions enable MBH to search the solution space faster and more thoroughly. In developing this explanation, we use the concepts of sub-diffusive, normally-diffusive, and super-diffusive random walks (RWs) originally developed in the field of statistical physics

Walking the Filament of Feasibility: Global Optimization of Highly-Constrained, Multi-Modal Interplanetary Trajectories Using a Novel Stochastic Search Technique

Interplanetary trajectory optimization problems are highly complex and are characterized by a large number of decision variables and equality and inequality constraints as well as many locally optimal solutions. Stochastic global search techniques, coupled with a large-scale NLP solver, have been shown to solve such problems but are inadequately robust when the problem constraints become very complex. In this work, we present a novel search algorithm that takes advantage of the fact that equality constraints effectively collapse the solution space to lower dimensionality. This new approach walks the filament'' of feasibility to efficiently find the global optimal solution

Cyberbullying Victimization and Behaviors Among Girls: Applying Research Findings in the Field

Abstract: Problem statement: Prior research on cyberbullying has been conducted; however specific research on gender differences has yet to be examined. The current study focuses on gender trends, specifically females, in cyberbullying victimization and behaviors. Approach: A survey was given to undergraduate students at Bridgewater State College in an effort to see what gender trends exist in cyberbullying behaviors. A pilot program focused on girls and cyberbullying is also examined in this article. Results: Preliminary results from both the survey and the pilot study have shown gender differences in regards to cyberbullying victimization and behaviors. Results suggest that females are more often involved in cyberbullying activities both as victims and perpetrators. Conclusion: The current study has found evidence of gender trends in regards to females and cyberbullying behaviors. Future research needs to be conducted to further examine the gender trends emerging in cyberbullying related behaviors

Multi-Objective Hybrid Optimal Control for Multiple-Flyby Interplanetary Mission Design Using Chemical Propulsion

Preliminary design of high-thrust interplanetary missions is a highly complex process. The mission designer must choose discrete parameters such as the number of flybys and the bodies at which those flybys are performed. For some missions, such as surveys of small bodies, the mission designer also contributes to target selection. In addition, real-valued decision variables, such as launch epoch, flight times, maneuver and flyby epochs, and flyby altitudes must be chosen. There are often many thousands of possible trajectories to be evaluated. The customer who commissions a trajectory design is not usually interested in a point solution, but rather the exploration of the trade space of trajectories between several different objective functions. This can be a very expensive process in terms of the number of human analyst hours required. An automated approach is therefore very desirable. This work presents such an approach by posing the impulsive mission design problem as a multiobjective hybrid optimal control problem. The method is demonstrated on several real-world problems

Inflation expectations surveys as predictors of inflation and behavior in financial and labor markets

Inflation (Finance) ; Forecasting ; Interest rates

An Automated Solution of the Low-Thrust Interplanetary Trajectory Problem

Preliminary design of low-thrust interplanetary missions is a highly complex process. The mission designer must choose discrete parameters such as the number of flybys, the bodies at which those flybys are performed, and in some cases the final destination. In addition, a time-history of control variables must be chosen that defines the trajectory. There are often many thousands, if not millions, of possible trajectories to be evaluated, which can be a very expensive process in terms of the number of human analyst hours required. An automated approach is therefore very desirable. This work presents such an approach by posing the mission design problem as a hybrid optimal control problem. The method is demonstrated on hypothetical missions to Mercury, the main asteroid belt, and Pluto

Evaluating recent trends in capital formation

Capital ; Industries ; Corporations - Finance

Why Learning Styles Matter For Student Achievement In College Economics

This paper explores the link between student achievement and student learning styles in a college microeconomics course, based on the Dunn and Dunn model of learning styles.  The Productivity Environmental Survey (PEPS) is utilized to measure learning style preferences for twenty elements.  Factor analysis is applied to reduce the multidimensional preferences to a smaller set of common factors that identify analytic, global or indifferent learning styles.  The common factors are used as explanatory variables to measure the correlation between student achievement and their learning styles.  The empirical methodology developed in this study also provides a test of the internal validity of the Dunn and Dunn model, the construct validity of the PEPS instrument and the predictive validity of the model.  The authors explain how the results of the current research could be utilized to more generally enhance student achievement in the instruction of introductory economics and potentially other subject matter