Boron-oxygen defect imaging in p-type Czochralski silicon

In this work, we demonstrate an accurate method for determining the effective boron-oxygen (BO) related defect density on Czochralski-grown silicon wafers using photoluminescence imaging. Furthermore, by combining a recently developed dopant density imaging technique and microscopic Fourier transform infrared spectroscopy measurements of the local interstitial oxygen concentration [Oi ], the BO-related defect density, [Oi ], and the boron dopant density from the same wafer were determined, all with a spatial resolution of 160 μm. The results clearly confirm the established dependencies of the BO-related defect density on [Oi ] and the boron dopant density and demonstrate a powerful technique for studying this important defect.This work was supported by the Australian Research Council (ARC) Future Fellowships program and the Australian Renewable Energy Agency (ARENA) fellowships program

Curate and storyspace: an ontology and web-based environment for describing curatorial narratives

Existing metadata schemes and content management systems used by museums focus on describing the heritage objects that the museum holds in its collection. These are used to manage and describe individual heritage objects according to properties such as artist, date and preservation requirements. Curatorial narratives, such as physical or online exhibitions tell a story that spans across heritage objects and have a meaning that does not necessarily reside in the individual heritage objects themselves. Here we present curate, an ontology for describing curatorial narratives. This draws on structuralist accounts that distinguish the narrative from the story and plot, and also a detailed analysis of two museum exhibitions and the curatorial processes that contributed to them. Storyspace, our web based interface and API to the ontology, is being used by curatorial staff in two museums to model curatorial narratives and the processes through which they are constructed

Formation of Relativistic Axion Stars

Axions and axion-like particles are compelling candidates for the missing dark matter of the universe. As they undergo gravitational collapse, they can form compact objects such as axion stars or even black holes. In this paper, we study the formation and distribution of such objects. First, we simulate the formation of compact axion stars using numerical relativity with aspherical initial conditions that could represent the final stages of axion dark matter structure formation. We show that the final states of such collapse closely follow the known relationship of initial mass and axion decay constant $f_a$. Second, we demonstrate with a toy model how this information can be used to scan a model density field to predict the number densities and masses of such compact objects. In addition to being detectable by the LIGO/VIRGO gravitational wave interferometer network for axion mass of $10^{-9} < m_a < 10^{-11}$ eV, we show using peak statistics that for $f_a < 0.2M_{pl}$, there exists a "mass gap" between the masses of axion stars and black holes formed from collapse

Dynamic transition and Shapiro-step melting in a frustrated Josephson-junction array

We consider a two-dimensional fully frustrated Josephson-junction array driven by combined direct and alternating currents. Interplay between the mode locking phenomenon, manifested by giant Shapiro steps in the current-voltage characteristics, and the dynamic phase transition is investigated at finite temperatures. Melting of Shapiro steps due to thermal fluctuations is shown to be accompanied by the dynamic phase transition, the universality class of which is also discussed

THE EFFECT OF KOREAN FOLK DANCE EXERCISE TO THE KINEMATIC PARAMETERS FOR DOWN STAIRCASE WALKING OF ELDERLY PEOPLE

According to the Statistics department of Korea in 1991, population aged over 65 years in 1970 was 991,000 people (3.1% of whole population) and it has increased to 3,370,000 people (10.7% of whole population) in 2000. By 2010 Korea will become a full-scale aged society with an estimated population of about 7.53 million, 13.7% of those being the elderly. This phenomenon was occurred primarily due to the fertility reduction by the family planning project which was held since 1962 and extension of average life expectancy. Compared to the foreign countries which manage the aging population over long periods of time, the growth of the elderly population in Korea was faster than any other country in the world. Thus, the preparation for this is very urgent matter. Aging changes their movements and activities of people. Physical and functional degradation due to the aging process affect muscle atrophy, muscle loss, and loss of muscle function (Schlicht, Camaione & Owen, 2001). Muscle weakness affects the balance keeping which is an important factor to cause a falling. Falling is the most common injury of elderly people and even a light fall seriously hurts the elderly and can often lead to death (Leibson, Toteson, Gabriel, Ransom & Melton, 2002). Elderly’s falling occured more often to elderly women than men and 60% of this accident happens during daily activities. Startzell et al. (2000) also indicated that stair decending falls occured three times more often than for stair ascending. Walking downstairs is not only an essential motion but also is the most fearful action for elderly’s daily life process. However, most previous research on the characteristics of stair walking were targeted to normal young people. Thus, in this study, Korean folk dance program as part of rhythmic movement exercise was applied to the elderly women for increasing dynamic balance, stalility and range of motion, and the determined effect of it will be analyzed selected kinematic parameters

Influence of blade aerodynamic model on prediction of helicopter rotor aeroacoustic signatures

Brown’s vorticity transport model has been used to investigate how the local blade aerodynamic model influences the quality of the prediction of the high-frequency airloads associated with blade–vortex interactions, and thus the accuracy with which the acoustic signature of a helicopter rotor can be predicted. The vorticity transport model can accurately resolve the structure of the wake of the rotor and allows significant flexibility in the way that the blade loading can be represented. The Second Higher-Harmonic Control Aeroacoustics Rotor Test was initiated to provide experimental insight into the acoustic signature of a rotor in cases of strong blade–vortex interaction. Predictions of two models for the local blade aerodynamics are compared with the test data. A marked improvement in accuracy of the predicted high-frequency airloads and acoustic signature is obtained when a lifting-chord model for the blade aerodynamics is used instead of a lifting-line-type approach. Errors in the amplitude and phase of the acoustic peaks are reduced, and the quality of the prediction is affected to a lesser extent by the computational resolution of the wake, with the lifting-chord model producing the best representation of the distribution of sound pressure below the rotor

Finite temperature Casimir pistons for electromagnetic field with mixed boundary conditions and its classical limit

In this paper, the finite temperature Casimir force acting on a two-dimensional Casimir piston due to electromagnetic field is computed. It was found that if mixed boundary conditions are assumed on the piston and its opposite wall, then the Casimir force always tends to restore the piston towards the equilibrium position, regardless of the boundary conditions assumed on the walls transverse to the piston. In contrary, if pure boundary conditions are assumed on the piston and the opposite wall, then the Casimir force always tend to pull the piston towards the closer wall and away from the equilibrium position. The nature of the force is not affected by temperature. However, in the high temperature regime, the magnitude of the Casimir force grows linearly with respect to temperature. This shows that the Casimir effect has a classical limit as has been observed in other literatures.Comment: 14 pages, 3 figures, accepted by Journal of Physics

Liberating Efimov physics from three dimensions

When two particles attract via a resonant short-range interaction, three particles always form an infinite tower of bound states characterized by a discrete scaling symmetry. It has been considered that this Efimov effect exists only in three dimensions. Here we review how the Efimov physics can be liberated from three dimensions by considering two-body and three-body interactions in mixed dimensions and four-body interaction in one dimension. In such new systems, intriguing phenomena appear, such as confinement-induced Efimov effect, Bose-Fermi crossover in Efimov spectrum, and formation of interlayer Efimov trimers. Some of them are observable in ultracold atom experiments and we believe that this study significantly broadens our horizons of universal Efimov physics.Comment: 17 pages, 5 figures, contribution to a special issue of Few-Body Systems devoted to Efimov Physic

Effects of Diversity on Multi-agent Systems: Minority Games

We consider a version of large population games whose agents compete for resources using strategies with adaptable preferences. The games can be used to model economic markets, ecosystems or distributed control. Diversity of initial preferences of strategies is introduced by randomly assigning biases to the strategies of different agents. We find that diversity among the agents reduces their maladaptive behavior. We find interesting scaling relations with diversity for the variance and other parameters such as the convergence time, the fraction of fickle agents, and the variance of wealth, illustrating their dynamical origin. When diversity increases, the scaling dynamics is modified by kinetic sampling and waiting effects. Analyses yield excellent agreement with simulations.Comment: 41 pages, 16 figures; minor improvements in content, added references; to be published in Physical Review