Cusp Volumes of Alternating Knots on Surfaces

We study the geometry of hyperbolic knots that admit alternating projections on embedded surfaces in closed 3-manifolds. We show that, under mild hypothesis, their cusp area admits two sided bounds in terms of the twist number of the alternating projection and the genus of the projection surface. As a result, we derive diagrammatic estimates of slope lengths and give applications to Dehn surgery. These generalize results of Lackenby and Purcell about alternating knots in the 3-sphere. Using a result of Kalfagianni and Purcell, we point out that alternating knots on surfaces of higher genus, can have arbitrarily small cusp density, in contrast to alternating knots on spheres whose cusp densities are bounded away from zero due to Lackenby and Purcell.Comment: 48 pages, 16 figures; Typo of $\chi(F)<0$ fixed to $\chi(F)\le 0$ in main theore

SILICON ON INSULATOR BIPOLAR JUNCTION TRANSISTORS FOR FLEXIBLE MICROWAVE APPLICATIONS

Microwave frequency flexible electronic devices require a high quality semiconducting material and a set of fabrication techniques that are compatible with device integration onto flexible polymer substrates. Over the past ten years, monocrystalline silicon nanomembranes (SiNMs) have been studied as a flexible semiconducting material that is compatible with industrial Si processing. Fabricated from commercial silicon on insulator (SOI) wafers, SiNMs can be transferred to flexible substrates using a variety of techniques. Due to their high carrier mobilities, SiNMs are a promising candidate for flexible microwave frequency devices. This dissertation presents fabrication techniques for flexible SiNM devices in general, as well as the progress made towards the development of a microwave frequency SiNM bipolar junction transistor (BJT). In order to overcome previous limitations associated with adhesion, novel methods for transfer printing of metal films and SiNMs are presented. These techniques enable transfer printing of a range of metal films and improve the alignment of small transfer printed SiNM devices. Work towards the development of a microwave frequency BJT on SOI for SiNM devices is also described. Utilizing a self-aligned polysilicon sidewall spacer technique, a BJT with an ultra-narrow base region is fabricated and tested. Two regimes of operation are identified and characterized under DC conditions. At low base currents, devices exhibited forward current gain as high as &#946;F = 900. At higher base current values, a transconductance of 59 mS was observed. Microwave scattering parameters were obtained for the BJTs under both biasing conditions and compared to unbiased measurements. Microwave frequency gain was not observed. Instead, bias-dependent non-reciprocal behavior was observed and examined. Limitations associated with the microwave impedance-matched electrode configuration are presented. High current densities in the narrow electrodes cause localized heating, which leads to electrode material damage and ultimately dopant diffusion in the BJT. Finally, device design improvements are proposed to address the problem of localized heating and increase device lifetime under testing conditions. High values for DC current gain suggest that future modifications should improve microwave frequency performance and measurement reproducibility

Using PlanetLab for network research: Myths, realities, and best practices

PlanetLab is a research testbed that supports 428 experiments on 276 sites, with 583 nodes in 30 countries. It has lowered the barrier to distributed experimentation in network measurement, peer-to-peer networks, content distribution

Coaches’ thinking process: Analysis of decisions related to tactics during sports games

peer reviewedA three-step model of coaches’ tactical thinking process is proposed: pre-interactive, interactive and post-interactive decisions. This study focuses on the interactive decisions. Its first objective was to verify if a coach is able to report these decisions at the end of a game. The second objective was to analyse the goals and factors inducing the decisions. Data were collected during and after four games directed by two coaches, one in basketball, and the other in volleyball. Their teams participated in the second division of the Belgian national championship (1998-1999). The research method was similar to that developed by Gilbert, Trudel, and Haughian (1999). Coaches reported a limited number (1 to 9) of tactical decisions immediately after each game. Decisions reported by the coaches and additional decisions selected by researchers from videotapes of the games were used for stimulated recall interviews. A total of 82 decisions were analysed with the basketball coach and 88 with the volleyball coach. Data analysis was considered separately for each coach. Calling time out, player substitutions, and tactical cues were the most frequently analysed decisions. Adapting the team strategy and providing information or directives were the priority goals of the decisions. Most of the decisions were determined by subjective field information

Guix-HPC Activity Report 2017–2018

Guix-HPC is a collaborative effort to bring reproducible software deployment to scientific workflows and high-performance computing (HPC). Guix-HPC builds upon the GNU Guix software deployment tool and aims to make it a better tool for HPC practitioners and scientists concerned with reproducible research.Guix-HPC was launched in September 2017 as a joint software development project involving three research institutes: Inria, the Max Delbrück Center for Molecular Medicine (MDC), and the Utrecht Bioinformatics Center (UBC). GNU Guix for HPC and reproducible science has received contributions from additional individuals and organizations, including Cray, Inc. and Tourbillion Technology.This report highlights key achievements of Guix-HPC between its launch date in September 2017 and today, February 2019

Does it pay to move from welfare to work?

The 1996 Personal Responsibility and Work Opportunity Reconciliation Act requires welfare recipients to lookfor work and has made it more difficult for nonworking recipients to remain on the welfare rolls. In addition,the economic boom of the 1990s and changes in federal and state policies have raised the net income gainassociated with moving from welfare to work. This paper analyzes data from a panel survey of single mothers, allof whom received welfare in February 1997. In 1999, those who left welfare and were working had a higherhousehold income and lower poverty rate, experienced a similar level of material hardship, engaged in feweractivities to make ends meet, and had lower expectations of experiencing hardship in the near future than didnonworking welfare recipients. Estimations of fixed-effect regressions of income that control for bothobservable and unobservable time-invariant characteristics show that monthly net income increases by$2.63 for every additional hour of work effort. About 60 percent of the observed monthly incomedifference between wage-reliant and welfare-reliant mothers can be attributed to differences intheir work effort. Thus, after welfare reform, it does pay to move from welfare to work. © 2002 by theAssociation for Public Policy Analysis and Management.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34846/1/10080_ftp.pd