Growth of III-V films by control of MBE growth front stoichiometry

For the growth of strain-layer materials and high quality single and multiple quantum wells, the instantaneous control of growth front stoichiometry is critical. The process of the invention adjusts the offset or phase of molecular beam epitaxy (MBE) control shutters to program the instantaneous arrival or flux rate of In and As4 reactants to grow InAs. The interrupted growth of first In, then As4, is also a key feature

MBE growth technology for high quality strained III-V layers

The III-V films are grown on large automatically perfect terraces of III-V substrates which have a different lattice constant, with temperature and Group III and V arrival rates chosen to give a Group III element stable surface. The growth is pulsed to inhibit Group III metal accumulation of low temperature, and to permit the film to relax to equilibrium. The method of the invention: (1) minimizes starting step density on sample surface; (2) deposits InAs and GaAs using an interrupted growth mode (0.25 to 2 monolayers at a time); (3) maintains the instantaneous surface stoichiometry during growth (As-stable for GaAs, In-stable for InAs); and (4) uses time-resolved RHEED to achieve aspects (1) through (3)

Closed loop fiber optic rotation sensor

An improved optical gyroscope is provided, of the type that passes two light components in opposite directions through an optic fiber coil, and which adds a small variable frequency to one of the light components to cancel the phase shift due to rotation of the coil. The amount of coil rotation from an initial orientation, is accurately determined by combining the two light components, one of which has a slightly increased frequency, to develop beats that each represent a predetermined angle of rotation. The direction of rotation is obtained by combining the two light components on a photodetector, intermittently phase shifting a single light component by 90 deg and comparing the direction of change of photodetector output (+ or -) caused by the 90 deg shift, with the slope (+ or -) of the photodetector output at about the same time, when there is a 90 deg shift

An approximate dynamic programming approach to food security of communities following hazards

Food security can be threatened by extreme natural hazard events for households of all social classes within a community. To address food security issues following a natural disaster, the recovery of several elements of the built environment within a community, including its building portfolio, must be considered. Building portfolio restoration is one of the most challenging elements of recovery owing to the complexity and dimensionality of the problem. This study introduces a stochastic scheduling algorithm for the identification of optimal building portfolio recovery strategies. The proposed approach provides a computationally tractable formulation to manage multi-state, large-scale infrastructure systems. A testbed community modeled after Gilroy, California, is used to illustrate how the proposed approach can be implemented efficiently and accurately to find the near-optimal decisions related to building recovery following a severe earthquake.Comment: As opposed to the preemptive scheduling problem, which was addressed in multiple works by us, we deal with a non-preemptive stochastic scheduling problem in this work. Submitted to 13th International Conference on Applications of Statistics and Probability in Civil Engineering, ICASP13 Seoul, South Korea, May 26-30, 201

Estimating the Value of Medal Success at the 2010 Winter Olympic Games

We estimate Canadians’ willingness to pay (WTP) for success by Team Canada in the 2010 Winter Olympics. The Canadian government subsidized elite athletes in the run up to the 2010 Games through the Own the Podium program, which was designed to increase Canada’s medal count. WTP estimates from a contingent valuation method (CVM) study using data from nationally representative surveys before and after the Games suggest that Own the Podium generated intangible benefits of between 3 and 5 times its cost. The aggregate value of the intangible benefits generated by the program was between $719 million and$3.4 billion. Key Words: Olympic Games, contingent valuation method, willingness to pay

The Changing Landscape for the Public Sector: The challenges of building digital bridges

The University of Technology Sydney, Institute for Public Policy and Governance (UTS:IPPG) has undertaken research to investigate how public sector leaders are responding to digital transformation. This research has carried out on behalf of Civica, a leading provider of software and services to local government. The study builds on previous UTS:IPPG and Civica research, The Changing Landscape for Local Government: A vision for 2025 This report presents the headline findings from the latest research which seeks to understand: • Driving forces for new ways of working in a digital society • What (if anything) is holding back digital changes to public sector service delivery • Views on the opportunities and future for ‘digital first’ organisations • Leadership capacity and skills required to drive digital change • Ideas for building a digital first organisational culture and mindset Following initial desktop research, a survey of public sector professionals and 1:1 interviews with leaders from the local government sector, the research findings reveal a number of insights into the challenges, opportunities and changing landscape of digital cultures in the public sector. This report provides a scaffold to help public sector organisations better understand and prepare for a digital-first future

Nuclear Black Hole Formation in Clumpy Galaxies at High Redshift

Massive stellar clumps in high redshift galaxies interact and migrate to the center to form a bulge and exponential disk in <1 Gyr. Here we consider the fate of intermediate mass black holes (BHs) that might form by massive-star coalescence in the dense young clusters of these disk clumps. We find that the BHs move inward with the clumps and reach the inner few hundred parsecs in only a few orbit times. There they could merge into a supermassive BH by dynamical friction. The ratio of BH mass to stellar mass in the disk clumps is approximately preserved in the final ratio of BH to bulge mass. Because this ratio for individual clusters has been estimated to be ~10^{-3}, the observed BH-to-bulge mass ratio results. We also obtain a relation between BH mass and bulge velocity dispersion that is compatible with observations of present-day galaxies.Comment: 10 pages, 3 figures, accepted by Ap

Are critical finite-size scaling functions calculable from knowledge of an appropriate critical exponent?

Critical finite-size scaling functions for the order parameter distribution of the two and three dimensional Ising model are investigated. Within a recently introduced classification theory of phase transitions, the universal part of the critical finite-size scaling functions has been derived by employing a scaling limit that differs from the traditional finite-size scaling limit. In this paper the analytical predictions are compared with Monte Carlo simulations. We find good agreement between the analytical expression and the simulation results. The agreement is consistent with the possibility that the functional form of the critical finite-size scaling function for the order parameter distribution is determined uniquely by only a few universal parameters, most notably the equation of state exponent.Comment: 11 pages postscript, plus 2 separate postscript figures, all as uuencoded gzipped tar file. To appear in J. Phys. A