The LpL^p boundedness of wave operators for Schr\"odinger Operators with threshold singularities

Let $H=-\Delta+V$ be a Schr\"odinger operator on $L^2(\mathbb R^n)$ with real-valued potential $V$ for $n > 4$ and let $H_0=-\Delta$. If $V$ decays sufficiently, the wave operators $W_{\pm}=s-\lim_{t\to \pm\infty} e^{itH}e^{-itH_0}$ are known to be bounded on $L^p(\mathbb R^n)$ for all $1\leq p\leq \infty$ if zero is not an eigenvalue, and on $1<p<\frac{n}{2}$ if zero is an eigenvalue. We show that these wave operators are also bounded on $L^1(\mathbb R^n)$ by direct examination of the integral kernel of the leading term. Furthermore, if $\int_{\mathbb R^n} V(x) \phi(x) \, dx=0$ for all eigenfunctions $\phi$, then the wave operators are $L^p$ bounded for $1\leq p<n$. If, in addition $\int_{\mathbb R^n} xV(x) \phi(x) \, dx=0$, then the wave operators are bounded for $1\leq p<\infty$.Comment: Incorporated referee comments and updated references. To appear in Adv. Mat

Experiences with a simplified microsimulation for the Dallas/Fort Worth area

We describe a simple framework for micro simulation of city traffic. A medium sized excerpt of Dallas was used to examine different levels of simulation fidelity of a cellular automaton method for the traffic flow simulation and a simple intersection model. We point out problems arising with the granular structure of the underlying rules of motion.Comment: accepted by Int.J.Mod.Phys.C, 20 pages, 14 figure

Tibial Acceleration in Male and Female Distance Runners in Reduced Body Weight Conditions

Seventy-two percent of all stress fractures in athletes come from running, which can cause an immediate cessation of training. Additionally, fifty percent of all stress fractures occur in the distal end of the tibia. One way to keep the athlete moving without slowing down the healing process is using an unloader treadmill (TM) in a rehabilitation setting. The purpose of this study was to investigate relationship between the level of body weight (BW) unloading in an Anti-Gravity Treadmill and tibial acceleration. Fifteen collegiate cross-country team runners (Gender: 9 males, 6 females; Age: 20.4 ± 2.4 years; Weight 60.1 ± 12.6 kg) were recruited for this study. Tibial acceleration was assessed through a skin-mounted accelerometer which was attached to the lower third of the tibialis. Results show no significant difference between mean peak tibial acceleration from a 100% BW to 60% BW conditions. There was a significant (p ≤ 0.05) difference from 100% BW to 60% BW in mean peak to peak accelerations, which is indicative of tibial stress. Additionally, significant differences were observed among stride rate and heart rate which decreased throughout all BW conditions which shows changes kinetic and metabolic demands. In order to effectively reduce tibial stress in runners, a runner would have to start at or below 60% of their BW. Tibial acceleration was not reduced due to the kinetic changes which occurred from a reduction in BW

Computer Based Learning - Dealing with Increasing Knowledge Volume and Declining Teaching Resources

Expanding knowledge in all disciplines, declining resources and staff for traditional lecture and practical or tutorial format in Australian Universities, and demands for knowledge construction and acquisition by students provides impetus for the development of new educational strategies. Computer assisted learning, (CAL) integrates large amounts of information and data in an active learning environment. CAL is an especially effective facility, through exercises that explore underlying processes and their interactions for students to develop knowledge and understanding. This paper recounts 15 years experience within agriculture and related disciplines, and addresses the sources of software and hardware, the special roles of dynamic simulation models, likely future developments and student responses to CAL. The paper shows that CAL is an effective means of teaching agriculturally oriented subjects that involve complex interactions, with student performance comparable to performance with other teaching strategies. Analysis of student surveys of acceptance of CAL shows both positive and negative responses, with resistance mostly related to low levels of computer literacy and perceived unfriendliness of some packages used

Development of school energy policy and energy education plans: A comparative case study in three Wisconsin school communities

Cataloged from PDF version of article.Through a qualitative comparative case study, this investigation examined the process by which three school districts in Wisconsin, U.S.A., developed a school energy policy and complementary energy education plan. To guide the process, the researchers created an outline of recommended steps for the districts to follow. Although there were variations in the sequence and perceived ease of the steps, the Energy Task Force members involved in the process found the outline to be a supportive guide. Further analysis of the cases involved interviewing members of the Energy Task Forces to identify facilitating and obstructing factors. The study concluded that factors such as level of environmental literacy, along with aspects of the school culture and leadership, interacted to influence the successful drafting of school energy policies and education plans. In addition to introducing an outline of recommended steps that can be used by other school policy development teams interested in promoting energy efficiency, this study adds insights into the analysis of energy policy work within the context of a school setting. & 2013 Elsevier Ltd. All rights reserved

Bulk and Surface Nucleation Processes in Ag2S Conductance Switches

We studied metallic Ag formation inside and on the surface of Ag2S thin films, induced by the electric field created with a STM tip. Two clear regimes were observed: cluster formation on the surface at low bias voltages, and full conductance switching at higher bias voltages (V > 70mV). The bias voltage at which this transition is observed is in agreement with the known threshold voltage for conductance switching at room temperature. We propose a model for the cluster formation at low bias voltage. Scaling of the measured data with the proposed model indicates that the process takes place near steady state, but depends on the STM tip geometry. The growth of the clusters is confirmed by tip retraction measurements and topography scans. This study provides improved understanding of the physical mechanisms that drive conductance switching in solid electrolyte memristive devices.Comment: In press for PR

Enhanced Accessibility for People with Disabilities Living in Urban Areas

[Excerpt] People with disabilities constitute a significant proportion of the poor in developing countries. If internationally agreed targets on reducing poverty are to be reached, it is critical that specific measures be taken to reduce the societal discrimination and isolation that people with disabilities continue to face. Transport is an important enabler of strategies to fight poverty through enhancing access to education, employment, and social services. This project aims to further the understanding of the mobility and access issues experienced by people with disabilities in developing countries, and to identify specific steps that can be taken to start addressing problems. A major objective of the project is to compile a compendium of guidelines that can be used by government authorities, advocacy groups, and donor/loan agencies to improve the access of people with disabilities to transport and other services in urban areas

A Cellular Automaton Model for Bi-Directionnal Traffic

We investigate a cellular automaton (CA) model of traffic on a bi-directional two-lane road. Our model is an extension of the one-lane CA model of {Nagel and Schreckenberg 1992}, modified to account for interactions mediated by passing, and for a distribution of vehicle speeds. We chose values for the various parameters to approximate the behavior of real traffic. The density-flow diagram for the bi-directional model is compared to that of a one-lane model, showing the interaction of the two lanes. Results were also compared to experimental data, showing close agreement. This model helps bridge the gap between simplified cellular automata models and the complexity of real-world traffic.Comment: 4 pages 6 figures. Accepted Phys Rev

Fuzzy cellular model for on-line traffic simulation

This paper introduces a fuzzy cellular model of road traffic that was intended for on-line applications in traffic control. The presented model uses fuzzy sets theory to deal with uncertainty of both input data and simulation results. Vehicles are modelled individually, thus various classes of them can be taken into consideration. In the proposed approach, all parameters of vehicles are described by means of fuzzy numbers. The model was implemented in a simulation of vehicles queue discharge process. Changes of the queue length were analysed in this experiment and compared to the results of NaSch cellular automata model.Comment: The original publication is available at http://www.springerlink.co