2,991 research outputs found

    Why Labor Unions Have Grown Reluctant To Use the “S” Word. Global, High-Tech Economy Makes Striking Riskier As Membership Declines. A Sense of Shared Purpose, 1999

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    Newspaper article about strikes and the role of unions in strikes, The Wall Street Journal. Vol. 104, No. 118, December 16, 1999

    Using an Open Software System (Sakai) to Develop Student Portfolios

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    E-portfolios are digital collections of artifacts that represent the achievements and reflections of individuals. They offer a unique view into student learning and allow educators and external accreditors to assess student progress towards established standards as well as reviewing their program’s performance in supporting that progress. Students benefit from assembling their e-portfolios through the process of reviewing their own work with a critical eye, choosing pieces of their work that best represent their abilities, and reflecting on the transformative nature of their University experience, both in class and through extra-curricular, service learning, internships and international activities. An e-portfolio provides a holistic view of a student’s personal growth and abilities that will serve them well in their career search or graduate school application. The challenge for an institution is to provide this learning and assessment resource in an accessible and affordable vehicle that is manageable for both faculty and students. Roger Williams University has crafted a strategy to utilize the Sakai open source course management system with its integrated e-portfolio tool set and a linked website to provide both e-portfolios and program assessment. This strategy will also be employed to propose a virtual accreditation of a professional program that will serve as a model throughout the University and the broader higher education community

    Demonstration of non-Markovian process characterisation and control on a quantum processor

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    In the scale-up of quantum computers, the framework underpinning fault-tolerance generally relies on the strong assumption that environmental noise affecting qubit logic is uncorrelated (Markovian). However, as physical devices progress well into the complex multi-qubit regime, attention is turning to understanding the appearance and mitigation of correlated -- or non-Markovian -- noise, which poses a serious challenge to the progression of quantum technology. This error type has previously remained elusive to characterisation techniques. Here, we develop a framework for characterising non-Markovian dynamics in quantum systems and experimentally test it on multi-qubit superconducting quantum devices. Where noisy processes cannot be accounted for using standard Markovian techniques, our reconstruction predicts the behaviour of the devices with an infidelity of 10310^{-3}. Our results show this characterisation technique leads to superior quantum control and extension of coherence time by effective decoupling from the non-Markovian environment. This framework, validated by our results, is applicable to any controlled quantum device and offers a significant step towards optimal device operation and noise reduction

    Filtering crosstalk from bath non-Markovianity via spacetime classical shadows

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    From an open system perspective non-Markovian effects due to a nearby bath or neighbouring qubits are dynamically equivalent. However, there is a conceptual distinction to account for: neighbouring qubits may be controlled. We combine recent advances in non-Markovian quantum process tomography with the framework of classical shadows to characterise spatiotemporal quantum correlations. Observables here constitute operations applied to the system, where the free operation is the maximally depolarising channel. Using this as a causal break, we systematically erase causal pathways to narrow down the progenitors of temporal correlations. We show that one application of this is to filter out the effects of crosstalk and probe only non-Markovianity from an inaccessible bath. It also provides a lens on spatiotemporally spreading correlated noise throughout a lattice from common environments. We demonstrate both examples on synthetic data. Owing to the scaling of classical shadows, we can erase arbitrarily many neighbouring qubits at no extra cost. Our procedure is thus efficient and amenable to systems even with all-to-all interactions.Comment: 5 pages, 4 figure

    Defining the gap between research and practice in public relations programme evaluation - towards a new research agenda

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    The current situation in public relations programme evaluation is neatly summarized by McCoy who commented that 'probably the most common buzzwords in public relations in the last ten years have been evaluation and accountability' (McCoy 2005, 3). This paper examines the academic and practitioner-based literature and research on programme evaluation and it detects different priorities and approaches that may partly explain why the debate on acceptable and agreed evaluation methods continues. It analyses those differences and proposes a research agenda to bridge the gap and move the debate forward

    Preliminary Experience With 3-Tesla MRI and Cushing\u27s Disease

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    Because radiographic visualization of a pituitary microadenoma is frequently difficult, we hypothesized that microadenomas associated with Cushing\u27s disease may be better resolved and localized via acquisition with 3-Tesla (3T) compared with standard 1.5-Tesla (1.5T) magnetic resonance imaging (MRI). Five patients (four females, one male; age range, 14 to 50 years old) with endocrine and clinical confirmation of Cushing\u27s disease underwent 1.5T and 3T MRI and corticotropin-releasing hormone stimulation/inferior petrosal sinus sampling (IPSS) as part of their preoperative evaluation. All patients underwent a transnasal trans-sphenoidal pituitary adenomectomy. In two cases, tumor could not be localized on either 1.5T or 3T MRI on the initial radiologist\u27s review. In two other cases, the 1.5T images delineated the tumor location, but it was more clearly defined on 3T MRI. In a fifth case, the 1.5T MRI showed a probable right-sided adenoma. However, on both 3T MRI and at surgical exploration the tumor was localized on the left side. Therefore, in three of five cases, 3T MRI either more clearly defined tumors seen on 1.5T MRI or predicted the location of tumor contrary to the 1.5T images. IPSS identified the correct side of the tumor in two patients, an incorrect location in two patients, and was indeterminate in one patient. In certain cases 3T MRI is a new tool that may ameliorate imaging difficulties associated with adrenocorticotrophic hormone-secreting pituitary adenomas. Its role in the diagnostic evaluation of Cushing\u27s disease will be better defined with further experience. Copyright © 2007 by Thieme Medical Publishers, Inc

    On the sampling complexity of open quantum systems

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    Open quantum systems are ubiquitous in the physical sciences, with widespread applications in the areas of chemistry, condensed matter physics, material science, optics, and many more. Not surprisingly, there is significant interest in their efficient simulation. However, direct classical simulation quickly becomes intractable with coupling to an environment whose effective dimension grows exponentially. This raises the question: can quantum computers help model these complex dynamics? A first step in answering this question requires understanding the computational complexity of this task. Here, we map the temporal complexity of a process to the spatial complexity of a many-body state using a computational model known as the process tensor framework. With this, we are able to explore the simulation complexity of an open quantum system as a dynamic sampling problem: a system coupled to an environment can be probed at successive points in time -- accessing multi-time correlations. The complexity of multi-time sampling, which is an important and interesting problem in its own right, contains the complexity of master equations and stochastic maps as a special case. Our results show how the complexity of the underlying quantum stochastic process corresponds to the complexity of the associated family of master equations for the dynamics. We present both analytical and numerical examples whose multi-time sampling is as complex as sampling from a many-body state that is classically hard. This also implies that the corresponding family of master equations are classically hard. Our results pave the way for studying open quantum systems from a complexity-theoretic perspective, highlighting the role quantum computers will play in our understanding of quantum dynamics

    Discovery of a Radio-Selected z ~ 6 Quasar

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    We present the discovery of only the second radio-selected, z ~ 6 quasar. We identified SDSS J222843.54+011032.2 (z=5.95) by matching the optical detections of the deep Sloan Digital Sky Survey (SDSS) Stripe 82 with their radio counterparts in the Stripe82 VLA Survey. We also matched the Canadian-France-Hawaiian Telescope Legacy Survey Wide (CFHTLS Wide) with the Faint Images of the Radio Sky at Twenty-cm (FIRST) survey but have yet to find any z ~ 6 quasars in this survey area. The discovered quasar is optically-faint, z = 22.3 and M_{1450} ~ -24.5, but radio-bright, with a flux density of f1.4GHz,peak_{1.4GHz, peak} = 0.31mJy and a radio-loudness of R ~ 1100 (where R = f_{5GHz}/f_{2500}). The i-z color of the discovered quasar places it outside the color selection criteria for existing optical surveys. We conclude by discussing the need for deeper wide-area radio surveys in the context of high-redshift quasars.Comment: 20 pages, 6 figures, and ApJ accepte

    Non-Markovian Quantum Process Tomography

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    Characterisation protocols have so far played a central role in the development of noisy intermediate-scale quantum (NISQ) computers capable of impressive quantum feats. This trajectory is expected to continue in building the next generation of devices: ones that can surpass classical computers for particular tasks -- but progress in characterisation must keep up with the complexities of intricate device noise. A missing piece in the zoo of characterisation procedures is tomography which can completely describe non-Markovian dynamics. Here, we formally introduce a generalisation of quantum process tomography, which we call process tensor tomography. We detail the experimental requirements, construct the necessary post-processing algorithms for maximum-likelihood estimation, outline the best-practice aspects for accurate results, and make the procedure efficient for low-memory processes. The characterisation is the pathway to diagnostics and informed control of correlated noise. As an example application of the technique, we improve multi-time circuit fidelities on IBM Quantum devices for both standalone qubits and in the presence of crosstalk to a level comparable with the fault-tolerant noise threshold in a variety of different noise conditions. Our methods could form the core for carefully developed software that may help hardware consistently pass the fault-tolerant noise threshold
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