Automatic software for controlling cryogenic systems

A technical discussion of the lessons learned during the seven years of software development/testing which occurred on the Liquid Oxygen System for the Space Shuttle at the Kennedy Space Center is given. Problems which were solved during these years came into four distinct phases: design/debug before simulation runs, verification using simulation with models up through Space Transportation System-1 launch, hardware usage from first launch to Space Transportation System-5 launch, and future use. Each problem/solution describes the apparent problem requirements/constraints, usable alternatives, selected action, and results

Against Conventional Wisdom

Conventional wisdom has it that truth is always evaluated using our actual linguistic conventions, even when considering counterfactual scenarios in which different conventions are adopted. This principle has been invoked in a number of philosophical arguments, including Kripke’s defense of the necessity of identity and Lewy’s objection to modal conventionalism. But it is false. It fails in the presence of what Einheuser (2006) calls c-monsters, or convention-shifting expressions (on analogy with Kaplan’s monsters, or context-shifting expressions). We show that c-monsters naturally arise in contexts, such as metalinguistic negotiations, where speakers entertain alternative conventions. We develop an expressivist theory—inspired by Barker (2002) and MacFarlane (2016) on vague predications and Einheuser (2006) on counterconventionals—to model these shifts in convention. Using this framework, we reassess the philosophical arguments that invoked the conventional wisdom

Quantum state targeting

We introduce a new primitive for quantum communication that we term "state targeting" wherein the goal is to pass a test for a target state even though the system upon which the test is performed is submitted prior to learning the target state's identity. Success in state targeting can be described as having some control over the outcome of the test. We show that increasing one's control above a minimum amount implies an unavoidable increase in the probability of failing the test. This is analogous to the unavoidable disturbance to a quantum state that results from gaining information about its identity, and can be shown to be a purely quantum effect. We provide some applications of the results to the security analysis of cryptographic tasks implemented between remote antagonistic parties. Although we focus on weak coin flipping, the results are significant for other two-party protocols, such as strong coin flipping, partially binding and concealing bit commitment, and bit escrow. Furthermore, the results have significance not only for the traditional notion of security in cryptography, that of restricting a cheater's ability to bias the outcome of the protocol, but also on a novel notion of security that arises only in the quantum context, that of cheat-sensitivity. Finally, our analysis of state targeting leads to some interesting secondary results, for instance, a generalization of Uhlmann's theorem and an operational interpretation of the fidelity between two mixed states

The Arithmetic of Word Ladders

The relationship between word games and mathematical recreations is well-known. Martin Gardner has often described them in his Mathematical Games column in the Scientific American. The editor of WORD WAYS, in his recent book BEYOND LANGUAGE, has derived logological structures from mathematical ones

Imitating Ho Chi Minh

Famous- or infamous- statesmen are not above indulging in word games. Ho Chi Minh, President of the Democratic Republic of Vietnam, while a prisoner in China, circa 1943, whiled his time away by writing poems. He wrote them in classical Chinese, not in Vietnamese, lest his jailers become suspicious. They have been translated into English in the cited work

Degradation of a quantum reference frame

We investigate the degradation of reference frames, treated as dynamical quantum systems, and quantify their longevity as a resource for performing tasks in quantum information processing. We adopt an operational measure of a reference frame's longevity, namely, the number of measurements that can be made against it with a certain error tolerance. We investigate two distinct types of reference frame: a reference direction, realized by a spin-j system, and a phase reference, realized by an oscillator mode with bounded energy. For both cases, we show that our measure of longevity increases quadratically with the size of the reference system and is therefore non-additive. For instance, the number of measurements that a directional reference frame consisting of N parallel spins can be put to use scales as N^2. Our results quantify the extent to which microscopic or mesoscopic reference frames may be used for repeated, high-precision measurements, without needing to be reset - a question that is important for some implementations of quantum computing. We illustrate our results using the proposed single-spin measurement scheme of magnetic resonance force microscopy.Comment: 9 pages plus appendices, 4 figures, published versio

Fundy Tidal Power: A Need to Reassess the Environmental Framework Protecting the Transboundary Environment

The concept of harnessing the tides for energy is receiving renewed attention in the maritime provinces of Canada and northeastern United States where a scarcity of indigenous energy resources exists. While proposals for several small tidal power facilities are being considered in Maine, in Canada, Nova Scotia officials are moving ahead with plans for a major tidal power project (4,028 MW) in the Minas Basin in the Bay of Fundy. The vast majority of the power generated from this facility is expected to be exported to the New York and New England areas which have a greater energy demand that the maritime provinces. Although tidal power facilities have been proposed for the Minas Basin in the past, a recent update of the current economic feasibility of such a project shows the benefits far surpassing the costs. However, while tidal power is traditionally considered to have minimal impacts on the environment, there is some scientific evidence which suggests that the proposed facility may affect the tidal regime as far south as Cape Cod, Massachusetts due to the unique oceanographic conditions found in the Gulf of Maine and Bay of Fundy. A recent analysis undertaken through funding by the Maine State Planning Office indicates that such an alteration to the tidal regime could have far-reaching environmental consequences ranging from loss of terrestrial habitats to possible weather modification. In addition to these physical consequences however, this project could have significant implications for environmental law. This thesis examines both international environmental law and the domestic laws of Canada and the United States which attempt to protect the transboundary environment. Canadian-United States practice with prior transboundary environmental problems is examined with respect to how these disputes have been settled in the past. The results of this analysis suggest that there are several deficiencies in the present international and domestic legal framework which do not adequately protect the transboundary environment. The boundary Waters Treaty of 1909 and its working mechanism, the International Join Commission do, however, appear to provide the necessary base for addressing transboundary environmental problems and need to be utilized to a greater extent in resolving environmental disputes between the two countries