Index theorems on manifolds with straight ends

We study Fredholm properties and index formulas for Dirac operators over complete Riemannian manifolds with straight ends. An important class of examples of such manifolds are complete Riemannian manifolds with pinched negative sectional curvature and finite volume

Design of a 3 GHz Accelerator Structure for the CLIC Test Facility (CTF 3) Drive Beam

For the CLIC two-beam scheme, a high-current, long-pulse drive beam is required for RF power generation. Taking advantage of the 3 GHz klystrons available at the LEP injector once LEP stops, a 180 MeV electron accelerator is being constructed for a nominal beam current of 3.5 A and 1.5 microsecond pulse length. The high current requires highly effective suppression of dipolar wakes. Two concepts are investigated for the accelerating structure design: the "Tapered Damped Structure" developed for the CLIC main beam, and the "Slotted Iris - Constant Aperture" structure. Both use 4 SiC loads per cell for effective higher-order mode damping. A full-size prototype of the TDS structure has been built and tested successfully at full power. A first prototype of the SICA structure is being built.Comment: Contribution to Linac 2000 Conference, TUA16 (Poster

The 30 GHz transfer structure for the CLIC study

In the so-called "Two-Beam Acceleration Scheme" the energy of a drive beam is converted to rf power by means of a "Transfer Structure", which plays the role of power source. In the Transfer Structure the bunched drive beam is decelerated by the electromagnetic field which it induces and builds up by the coherent interaction of successive bunches with the chosen longitudinal mode. The CLIC Transfer Structure is original in that it operates at 30 GHz and uses teeth-like corrugations to slow down the hybrid TM mode to make it synchronous with the drive beam. The beam energy is transformed into rf power, which travels along the structure and is collected by the output couplers. The 30 GHz rf power is then transported by means of two waveguides to two main linac disk-loaded accelerating structures. This report describes the CLIC Transfer Structure design, 3-D computer simulations, model construction and measure-ments as well as the prototype construction and testing with the low energy beam in the CLIC Test Facility. The result of this development is a compact, fully passive, relatively simple and low cost device, which offers a readily scalable solution to the problem of rf power extraction from high frequency bunched beams

Cohesion, team mental models, and collective efficacy: Towards an integrated framework of team dynamics in sport

A nomological network on team dynamics in sports consisting of a multi-framework perspective is introduced and tested. The aim was to explore the interrelationship among cohesion, team mental models (TMM), collective-efficacy (CE), and perceived performance potential (PPP). Three hundred and forty college-aged soccer players representing 17 different teams (8 female and 9 male) participated in the study. They responded to surveys on team cohesion, TMM, CE and PPP. Results are congruent with the theoretical conceptualization of a parsimonious view of team dynamics in sports. Specifically, cohesion was found to be an exogenous variable predicting both TMM and CE beliefs. TMM and CE were correlated and predicted PPP, which in turn accounted for 59% of the variance of objective performance scores as measured by teams’ season record. From a theoretical standpoint, findings resulted in a parsimonious view of team dynamics, which may represent an initial step towards clarifying the epistemological roots and nomological network of various team-level properties. From an applied standpoint, results suggest that team expertise starts with the establishment of team cohesion. Following the establishment of cohesiveness, teammates are able to advance team-related schemas and a collective sense of confidence. Limitations and key directions for future research are outlined

Growing FLORES for the Museum

The Children's Museum of Indianapolis, founded in 1925, is one of few children's museums with a substantial collection. The changing needs of family audiences, and the museum's shift in direction toward a family learning mission, began to raise several questions for the collections and curatorial staff regarding the selection of objects that would hold the greatest potential for use with family audiences. The questions led to the development of the Family Learning Object Rating and Evaluation System (FLORES). This case study describes the development of the rating instrument and strategies the team took to fine-tune its use through input from curators and museum visitor preferences. By drawing on inherent object qualities as well as visitor preferences, museums can find ways to better understand the visitor-object relationship and in turn move toward more intentional selection and inclusion of objects in exhibition planning

Modelling of precipitation during friction stir welding of an Al-Mg-Si alloy

In this study, microstructural evolution in AA 6082-T651 friction stir welds is simulated using a metallurgical model coupling a Monte Carlo random sampling technique and classical nucleation and growth theory. The calculated volume fraction and size distribution of precipitates are used to predict hardness. Some of the model parameters are calibrated from microstructure and hardness data available in the open literature. Temperature and hardness data in the region of the weld are obtained from FSW experiments. The temperature in the weld is predicted by finite element analysis, with a simplified thermo-mechanical approach, after calibration of heat transfer parameters in order to match the temperature measurements. The calculated thermal cycles are then applied to the metallurgical model. The subsequently predicted hardness profiles across the weld are then compared with experimental data