The Leadership Process and Its Effects on Self-Managed Work Groups in American Manufacturing Companies

Over the past 75 years, leadership has become a widely studied phenomenon, with many theories and models offered to assist the layman to become an effective leader. Most of these theories have been based on management models, that is, models that adapt management behaviors and goals into what the authors call leadership. These theories fall into several categories: great man, trait, contingency and situational among others. While these theories have provided practitioners some valid ideas on how to improve their managerial effectiveness, they have done little in the way of expanding the knowledge of the process of leadership. This study sought to examine leadership as a process. One definition of leadership was selected and tested against the feelings and attitudes of over 100 work team members from various manufacturing companies in the United States. The intent was to prove or disprove this model of leadership within these work teams--to examine the process of leadership at work at the lowest level in organizations, rather than the popular practice of considering the chief executive of the corporation and their personal habits, behaviors or traits. A survey instrument was designed to test the leadership model selected and distributed to volunteer participants who were members of self-managed work teams within manufacturing companies. This information was supplemented with a few interviews to clarify and triangulate the data. Statistical analyses were performed to determine if the test model was valid within these settings. The author concludes that the test model of leadership is valid in all respects within the teams themselves. From outside the teams, it was found that the model did not hold valid in all respects. The author believes this is due to the nature of the self-managed teams and their independence from traditional management influence

Substance Abuse via Legally Prescribed Drugs: The Case of Vicodin in the United States

Vicodin is the most commonly prescribed pain reliever in the United States. Research indicates that there are two million people who are currently abusing Vicodin, and the majority of those who abuse Vicodin were initially exposed to it via prescription. Our goal is to determine the most effective strategies for reducing the overall population of Vicodin abusers. More specifically, we focus on whether prevention methods aimed at educating doctors and patients on the potential for drug abuse or treatment methods implemented after a person abuses Vicodin will have a greater overall impact. We consider one linear and two non-linear compartmental models in which medical users of Vicodin can transition into the abuser compartment or leave the population by no longer taking the drug. Once Vicodin abusers, people can transition into a treatment compartment, with the possibility of leaving the population through successful completion of treatment or of relapsing and re-entering the abusive compartment. The linear model assumes no social interaction, while both non-linear models consider interaction. One considers interaction with abusers affecting the relapse rate, while the other assumes both this and an additional interaction between the number of abusers and the number of new prescriptions. Sensitivity analyses are conducted varying the rates of success of these intervention methods measured by the parameters to determine which strategy has the greatest impact on controlling the population of Vicodin abusers. From these models and analyses, we determine that manipulating parameters tied to prevention measures has a greater impact on reducing the population of abusers than manipulating parameters associated with treatment. We also note that increasing the rate at which abusers seek treatment affects the population of abusers more than the success rate of treatment itself

Optimal Control in the Treatment of Retinitis Pigmentosa

Numerous therapies have been implemented in an effort to minimize the debilitating effects of the degenerative eye disease Retinitis Pigmentosa (RP), yet none have provided satisfactory long-term solution. To date there is no treatment that can halt the degeneration of photoreceptors. The recent discovery of the RdCVF protein has provided researchers with a potential therapy that could slow the secondary wave of cone death. In this work, we build on an existing mathematical model of photoreceptor interactions in the presence of RP and incorporate various treatment regiments via RdCVF. Our results show that an optimal control exists for the administration of RdCVF. In addition, our numerical solutions show the experimentally observed rescue effect that the RdCVF has on the cones

Optimal control with MANF treatment of photoreceptor degeneration

People afflicted with diseases such as retinitis pigmentosa and age-related macular degeneration experience a decline in vision due to photoreceptor degeneration, which is currently unstoppable and irreversible. Currently there is no cure for diseases linked to photoreceptor degeneration. Recent experimental work showed that mesencephalic astrocyte-derived neurotrophic factor (MANF) can reduce neuron death and, in particular, photoreceptor death by reducing the number of cells that undergo apoptosis. In this work, we build on an existing system of ordinary differential equations that represent photoreceptor interactions and incorporate MANF treatment for three experimental mouse models having undergone varying degrees of photoreceptor degeneration. Using MANF treatment levels as controls, we investigate optimal control results in the three mouse models. In addition, our numerical solutions match the experimentally observed surviving percentage of photoreceptors and our uncertainty and sensitivity analysis identifies significant parameters in the math model both with and without MANF treatment

Who Says We R(o) Ready for Change?

18 pages, 1 article*Who Says We R(o) Ready for Change?* (Crisosto, Nicolas M.; Castillo-Chavez, Carlos; Kribs-Zaleta, Christopher; Wirkus, Stephen) 18 page

Mass-modulation schemes for a class of wave energy converters: Experiments, models, and efficacy

In a recent series of works, mass-modulation schemes have been proposed for a class of ocean wave energy converter (WEC). The goal of the schemes is to improve the energy harvesting capabilities of these devices by taking advantage of the ambient water. However this improvement comes at the cost of increased system complexity and possible impulse loadings at the instances where the mass changes. In the present work, experimental results for a pair of these schemes are presented and one of them is shown to be effective in increasing the energy harvesting potential of a WEC. Building and testing prototype WECs are costly and challenging and so, in order to examine as wide a range of parameters and designs as possible, a detailed two degree-of-freedom model is developed for a WEC equipped with a mass-modulation scheme. Numerical analysis of the model also shows the potential benefits of the mass-modulation scheme

A course in ordinary differential equations

Suitable for a first undergraduate course, the book includes all the basics necessary to prepare students for their future studies in mathematics, engineering, and the sciences. It presents the syntax from MATLAB, Maple, and Mathematica to give students a better grasp of the theory and gain more insight into real-world problems. Along with covering traditional topics, the text describes a number of modern topics, such as direction fields, phase lines, the Runge-Kutta method, and epidemiological and ecological models. It also explains concepts from linear algebra so that students acquire a thorough understanding of differential equations