Resonantly phase-matched Josephson junction traveling wave parametric amplifier

We develop a technique to overcome phase-mismatch in Josephson-junction traveling wave parametric amplifiers in order to achieve high gain over a broad bandwidth. Using "resonant phase matching," we design a compact superconducting device consisting of a transmission line with subwavelength resonant inclusions that simultaneously achieves a gain of 20 dB, an instantaneous bandwidth of 3 GHz, and a saturation power of -98 dBm. Such an amplifier is well-suited to cryogenic broadband microwave measurements such as the multiplexed readout of quantum coherent circuits based on superconducting, semiconducting, or nano-mechanical elements as well as traditional astronomical detectors.Comment: 8 pages, 5 figures, with appendice

Assessment of Composite Delamination Self-Healing Under Cyclic Loading

Recently, the promise of self-healing materials for enhanced autonomous durability has been introduced using a micro-encapsulation technique where a polymer based healing agent is encapsulated in thin walled spheres and embedded into a base polymer along with a catalyst phase. For this study, composite skin-stiffener flange debonding specimens were manufactured from composite prepreg containing interleaf layers with a polymer based healing agent encapsulated in thin-walled spheres. Constant amplitude fatigue tests in three-point bending showed the effect of self-healing on the fatigue response of the skin-stiffener flange coupons. After the cycling that created debonding, fatigue tests were held at the mean load for 24 hours. For roughly half the specimens tested, when the cyclic loading was resumed a decrease in compliance (increase in stiffness) was observed, indicating that some healing had occurred. However, with continued cycling, the specimen compliance eventually increased to the original level before the hold, indicating that the damage had returned to its original state. As was noted in a prevoius study conducted with specimens tested under monotonically increasing loads to failure, healing achieved via the micro-encapsulation technique may be limited to the volume of healing agent available relative to the crack volume

Measuring the Impact of the ‘Two Hours/Two Periods of Quality Physical Education’ Programme

No abstract available

An empirical investigation of the role of camaraderie, cause, competency, and participation motives in the development of attachment to a charity sport event

This paper examines the factors that contribute to the meaning participants hold for charity sport events. Specifically, the paper investigates the role of three value-laden constructs; along with participation motives, to understand participant attachment to a charity sport event. An online questionnaire was given to participants in the Lance Armstrong Foundation (LAF) LIVESTRONG Challenge (n=568) following the event. Data analysis revealed two recreational event motives, three motives for charitable giving, and three value-laden constructs contribute to attachment to the charity sport event. In addition, the results revealed the value-laden constructs make a stronger contribution to event attachment than the participation motives. Suggestions are made for increasing the meaning held for the event through community building, calls to action, and customization.Griffith Business School, Department of Tourism, Sport and Hotel ManagementFull Tex

Assessment of Composite Delamination Self-Healing Via Micro-Encapsulation

Composite skin/stringer flange debond specimens manufactured from composite prepreg containing interleaf layers with a polymer based healing agent encapsulated in thin walled spheres were tested. As a crack develops and grows in the base polymer, the spheres fracture releasing the healing agent. The agent reacts with catalyst and polymerizes healing the crack. In addition, through-thickness reinforcement, in the form of pultruded carbon z-pins were included near the flange tips to improve the resistance to debonding. Specimens were manufactured with 14 plies in the skin and 10 plies in the stiffener flange. Three-point bend tests were performed to measure the skin/stiffener debonding strength and the recovered strength after healing. The first three tests performed indicated no healing following unloading and reloading. Micrographs showed that delaminations could migrate to the top of the interleaf layer due to the asymmetric loading, and hence, bypass most of the embedded capsules. For two subsequent tests, specimens were clamped in reverse bending before reloading. In one case, healing was observed as evidenced by healing agent that leaked to the specimen edge forming a visible "scar". The residual strength measured upon reloading was 96% of the original strength indicating healing had occurred. Hence, self-healing is possible in fiber reinforced composite material under controlled conditions, i.e., given enough time and contact with pressure on the crack surfaces. The micro-encapsulation technique may prove more robust when capsule sizes can be produced that are small enough to be embedded in the matrix resin without the need for using an interleaf layer. However, in either configuration, the amount of healing that can occur may be limited to the volume of healing agent available relative to the crack volume that must be filled

Profiling executive dysfunction in adults with autism and comorbid learning disability

Executive dysfunction is thought to be primary to autism. We examined differences in executive function between 20 adults with autism and learning disability and 23 individuals with learning disabilities outside the autistic spectrum. All participants were matched for chronological age and full-scale IQ, and were given a battery of tasks assessing fluency, planning, set-shifting, inhibition and working memory. Analyses of the individual tasks revealed very few significant differences between the two groups. However, analyses of composite scores derived for each executive domain revealed that the group with autism showed impaired performance on the working memory and planning tests. Together, these two measures were sufficient to classify participants into their diagnostic groups significantly better than would be expected by chance (75% of the autism group; 65% of the control group). Executive impairments were neither universal nor exclusive to the autism group, and we suggest that an alternative cognitive theory may better explain the cognitive profile we found

Adiabatic elimination-based coupling control in densely packed subwavelength waveguides.

The ability to control light propagation in photonic integrated circuits is at the foundation of modern light-based communication. However, the inherent crosstalk in densely packed waveguides and the lack of robust control of the coupling are a major roadblock toward ultra-high density photonic integrated circuits. As a result, the diffraction limit is often considered as the lower bound for ultra-dense silicon photonics circuits. Here we experimentally demonstrate an active control of the coupling between two closely packed waveguides via the interaction with a decoupled waveguide. This control scheme is analogous to the adiabatic elimination, a well-known procedure in atomic physics. This approach offers an attractive solution for ultra-dense integrated nanophotonics for light-based communications and integrated quantum computing