6,145 research outputs found

    Non-Locality and Theories of Causation

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    The aim of the paper is to investigate the characterization of an unambiguous notion of causation linking single space-llike separated events in EPR-Bell frameworks. This issue is investigated in ordinary quantum mechanics, with some hints to no collapse formulations of the theory such as Bohmian mechanics.Comment: Presented at the NATO Advanced Research Workshop on Modality, Probability and Bell's Theorems, Cracow, Poland, August 19-23, 200

    The effect of flight line spacing on radioactivity inventory and spatial feature characteristics of airborne gamma-ray spectrometry data

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    Airborne Gamma Spectrometry (AGS) is well suited to the mapping of radioactivity in the environment. Flight parameters (e.g. speed and line spacing) directly affect the rate of area coverage, cost, and data quality of any survey. The influences of line spacing have been investigated for data from inter‐tidal, coastal and upland environments with a range of <sup>137</sup>Cs activity concentrations and depositional histories. Estimates of the integrated <sup>137</sup>Cs activity (‘inventory’) within specified areas and the shapes of depositional features were calculated for subsets of the data at different line spacings. Features with dimensions greater than the line spacing show variations in inventory and area of less than 3%, and features with dimensions less than the line spacing show larger variations and a decreased probability of detection. The choice of line spacing for a task is dependent on the dimensions of the features of interest and required edge definition. Options for line spacing for different tasks are suggested. It is noted that for regional mapping, even 5–10 km line spacing can produce useful data

    Continuing professional development for LIS professionals: Maximizing potential in an organizational context

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    Library and information science (LIS) professionals must be engaged in continuing professional development (CPD) to ensure their skills, knowledge and capabilities regularly to meet their own objectives and the requirements of employer organizations. This article highlights crucial issues relating to CPD in the interrelated contexts of the individual professional and their employer organization. We address three rhetorical questions: Are we willing to learn? Do we have opportunities to learn? Are we able to apply what we learn? Discussion and recommendations are drawn from relevant literature and grounded in workplace experience. Included are exemplar case studies from a large Australian academic library. Individuals' motivation and learning skill levels have significant impact on CPD effectiveness, as does the organizational learning climate. Professionals and employers jointly bear responsibility for CPD outcomes. LIS professionals should reflect on what motivates them towards continuous learning and organizations must create supportive learning environments. We find that both staff and employers are responsible for sourcing learning opportunities and utilizing effective learning transfer strategies. In this context, we recommend that a deliberate and thoughtful approach to CPD as this will result in increased benefits to LIS professionals and organizations

    Rapid prototyping of flexible models - a new methods for model testing?

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    To date hydroelastic towing tank models are generally segmented, flexible backbone or hinged models which provide an extremely limited representation of the ship structure and record loads only at a finite number of locations between segments. Fully flexible “hydro-structural” models, whilst providing a more accurate structural representation are rarely used due to expense and the complicated nature of their construction. Rapid prototyping is a powerful tool the potential of which is yet to be exploited in the marine industry. By using it to manufacture a realistic ship structure from materials of different properties, new model manufacturing paradigms may be explored. The focus of this paper is the initial findings from an investigation of the use of three-dimensional (3D) printing technologies for manufacturing structurally accurate flexible towing tank models. A detailed assessment is carried out of the material properties of 3D printed materials and their ability to model the scaled structural behaviour of a ship. Scaling implications when considering the realistic ship structure are presented and practical considerations for the construction of 3D printed towing tank models are discussed

    Functional rescue of dystrophin deficiency in mice caused by frameshift mutations using Campylobacter jejuni Cas9

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    Duchenne muscular dystrophy (DMD) is a fatal, X-linked muscle wasting disease caused by mutations in the DMD gene. In 51% of DMD cases, a reading frame is disrupted because of deletion of several exons. Here, we show that CjCas9 derived from Campylobacter jejuni can be used as a gene editing tool to correct an out-of-frame Dmd exon in Dmd knockout mice. Herein, we used Cas9 derived from S. pyogenes to generate Dmd knockout (KO) mice with a frameshift mutation in Dmd gene. Then, we expressed CjCas9, its single-guide RNA, and the eGFP gene in the tibialis anterior muscle of the Dmd KO mice using an all-in-one adeno-associated virus (AAV) vector. CjCas9 cleaved the target site in the Dmd gene efficiently in vivo and induced small insertions or deletions at the target site. This treatment resulted in conversion of the disrupted Dmd reading frame from out-of-frame to in-frame, leading to the expression of dystrophin in the sarcolemma. Importantly, muscle strength was enhanced in the CjCas9-treated muscles, without off-target mutations, indicating high efficiency and specificity of CjCas9. This work suggests that in vivo DMD frame correction, mediated by CjCas9 has great potential for the treatment of DMD and other neuromuscular diseases

    Quantum Computing and Hidden Variables I: Mapping Unitary to Stochastic Matrices

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    This paper initiates the study of hidden variables from the discrete, abstract perspective of quantum computing. For us, a hidden-variable theory is simply a way to convert a unitary matrix that maps one quantum state to another, into a stochastic matrix that maps the initial probability distribution to the final one in some fixed basis. We list seven axioms that we might want such a theory to satisfy, and then investigate which of the axioms can be satisfied simultaneously. Toward this end, we construct a new hidden-variable theory that is both robust to small perturbations and indifferent to the identity operation, by exploiting an unexpected connection between unitary matrices and network flows. We also analyze previous hidden-variable theories of Dieks and Schrodinger in terms of our axioms. In a companion paper, we will show that actually sampling the history of a hidden variable under reasonable axioms is at least as hard as solving the Graph Isomorphism problem; and indeed is probably intractable even for quantum computers.Comment: 19 pages, 1 figure. Together with a companion paper to appear, subsumes the earlier paper "Quantum Computing and Dynamical Quantum Models" (quant-ph/0205059
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