Robust Model Predictive Control for Signal Temporal Logic Synthesis

Most automated systems operate in uncertain or adversarial conditions, and have to be capable of reliably reacting to changes in the environment. The focus of this paper is on automatically synthesizing reactive controllers for cyber-physical systems subject to signal temporal logic (STL) specifications. We build on recent work that encodes STL specifications as mixed integer linear constraints on the variables of a discrete-time model of the system and environment dynamics. To obtain a reactive controller, we present solutions to the worst-case model predictive control (MPC) problem using a suite of mixed integer linear programming techniques. We demonstrate the comparative effectiveness of several existing worst-case MPC techniques, when applied to the problem of control subject to temporal logic specifications; our empirical results emphasize the need to develop specialized solutions for this domain

Detecting itinerant single microwave photons

Single photon detectors are fundamental tools of investigation in quantum optics and play a central role in measurement theory and quantum informatics. Photodetectors based on different technologies exist at optical frequencies and much effort is currently being spent on pushing their efficiencies to meet the demands coming from the quantum computing and quantum communication proposals. In the microwave regime however, a single photon detector has remained elusive although several theoretical proposals have been put forth. In this article, we review these recent proposals, especially focusing on non-destructive detectors of propagating microwave photons. These detection schemes using superconducting artificial atoms can reach detection efficiencies of 90\% with existing technologies and are ripe for experimental investigations.Comment: 11 pages, 8 figure

Gravitational Lorentz Violation and Superluminality via AdS/CFT Duality

A weak quantum mechanical coupling is constructed permitting superluminal communication within a preferred region of a gravitating AdS_5 spacetime. This is achieved by adding a spatially non-local perturbation of a special kind to the Hamiltonian of a four-dimensional conformal field theory with a weakly-coupled AdS dual, such as maximally supersymmetric Yang-Mills theory. In particular, two issues are given careful treatment: (1) the UV-completeness of our deformed CFT, guaranteeing the existence of a ``deformed string theory'' AdS dual, and (2) the demonstration that superluminal effects can take place in AdS, both on its boundary as well as in the bulk. Exotic Lorentz-violating properties such as these may have implications for tests of General Relativity, addressing the cosmological constant problem, or probing "behind'' horizons. Our construction may give insight into the interpretation of wormhole solutions in Euclidean AdS gravity.Comment: 23 pages LaTex. Typo in Eq. (37) corrected. References adde

The role of communication apprehension and self stigma of academic help-seeking in native and non-native English speakers: evidence from UK university students

Although communication apprehension (CA) has long been reported to hinder communication skills and academic attainment, its cumulative impact on self-stigma of academic help-seeking in a global education market has nevertheless been overlooked. The present study examined the relationship between CA and self-stigma of academic help-seeking among British university students who acquired English at different stages in their lives and its impact on achievement. Data were collected from 150 students who completed the Personal Report of Communication Apprehension (PRCA-24) and the self-stigma of academic help-seeking scale together with a demographic questionnaire. Overall, the findings showed a significant relationship between CA and self-stigma of academic help-seeking while age of English acquisition, residency status and level of study were also found to have a significant effect on the level of CA. The implications of the results are discussed within the higher education provision, pedagogy and psychological frameworks

Continuous vortex pumping into a spinor condensate with magnetic fields

We study the mechanisms and the limits of pumping vorticity into a spinor condensate through manipulations of magnetic (B-) fields. We discover a fundamental connection between the geometrical properties of the magnetic fields and the quantized circulation of magnetically trapped atoms, a result which generalizes several recent experimental and theoretical studies. The optimal procedures are devised that are capable of continuously increasing or decreasing a condensate's vorticity by repeating certain two step B-field manipulation protocols. We carry out detailed numerical simulations that support the claim that our protocols are highly efficient, stable, and robust against small imperfections of all types. Our protocols can be implemented experimentally within current technologies.Comment: 9 pages, 6 figure

Quantum and Classical Dynamics of a BEC in a Large-Period Optical Lattice

We experimentally investigate diffraction of a Rb-87 Bose-Einstein condensate from a 1D optical lattice. We use a range of lattice periods and timescales, including those beyond the Raman-Nath limit. We compare the results to quantum mechanical and classical simulations, with quantitative and qualitative agreement, respectively. The classical simulation predicts that the envelope of the time-evolving diffraction pattern is shaped by caustics: singularities in the phase space density of classical trajectories. This behavior becomes increasingly clear as the lattice period grows.Comment: 7 pages, 6 figure

Managing Equipment for Emergency Obstetric Care in Rural Hospitals

In resource poor countries substantial sums of money, from governments and international donors, are used to purchase equipment for health facilities. WHO estimates that 50-80% of such equipment remains non-functional. This article is based on the experiences from various projects in developing countries in Asia and Africa. The key issues in the purchase, distribution, installation, management and maintenance of equipment for emergency obstetric care (EmOC) services are identified and discussed. Some positive examples are described to show how common equipment management problems are solved.