44,107 research outputs found

    Positive Representations of Split Real Simply-laced Quantum Groups

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    We construct the positive principal series representations for Uq(gR)\mathcal{U}_q(\mathfrak{g}_\mathbb{R}) where g\mathfrak{g} is of simply-laced type, parametrized by R0r\mathbb{R}_{\geq 0}^r where rr is the rank of g\mathfrak{g}. We describe explicitly the actions of the generators in the positive representations as positive essentially self-adjoint operators on a Hilbert space, and prove the transcendental relations between the generators of the modular double. We define the modified quantum group Uqq~(gR)\mathbf{U}_{\mathfrak{q}\tilde{\mathfrak{q}}}(\mathfrak{g}_\mathbb{R}) of the modular double and show that the representations of both parts of the modular double commute weakly with each other, there is an embedding into a quantum torus algebra, and the commutant contains its Langlands dual.Comment: Finalized published version. Introduction has been rewritten to reflect recent progress and references added. Some typos fixe

    Hong Kong\u27s democratic movement and the making of China\u27s offshore civil society

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    Hong Kong\u27s civil society has remained vibrant since the sovereignty handover in 1997, thanks to an active defense by the democratic movement against Beijing\u27s attempts to control civil liberties. Hong Kong is becoming mainland China\u27s offshore civil society, serving as a free platform for information circulation and organizing among mainland activists and intellectuals

    Synthesis and properties of nickel-cobalt-boron nanoparticles

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    morphous cobalt nickel boride nanoparticles were synthesised by chemical reduction synthesis in aqueous solution. Careful control of synthesis conditions and post reaction oxidation enabled the nanoparticles to be converted into a core-shell structure comprising of an amorphous Co–Ni–B core and an outer metal oxide sheet. These particles had interesting magnetic properties including saturation magnetisations and coercivities of the order of 80 emu/g and 170 Oe respectively, making them suitable for a potential use as an exchange-pinned magnetic material

    Practitioner requirements for integrated Knowledge-Based Engineering in Product Lifecycle Management.

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    The effective management of knowledge as capital is considered essential to the success of engineering product/service systems. As Knowledge Management (KM) and Product Lifecycle Management (PLM) practice gain industrial adoption, the question of functional overlaps between both the approaches becomes evident. This article explores the interoperability between PLM and Knowledge-Based Engineering (KBE) as a strategy for engineering KM. The opinion of key KBE/PLM practitioners are systematically captured and analysed. A set of ranked business functionalities to be fulfiled by the KBE/PLM systems integration is elicited. The article provides insights for the researchers and the practitioners playing both the user and development roles on the future needs for knowledge systems based on PLM

    The future of ischemic stroke: flow from prehospital neuroprotection to definitive reperfusion.

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    Recent advances in ischemic stroke enable a seamless transition of the patient flow from the prehospital setting to definitive reperfusion, without the arbitrary separation of therapeutic phases of ischemia based on time alone. In 2013, the framework to understand and directly address the pathophysiology of cerebral blood flow that determines the timeline or evolution of ischemia in an individual case is given. This continuum of flow and the homeostasis of brain perfusion balanced by collaterals may be captured with serial imaging. Ongoing imaging core laboratory activities permit large-scale measurement of angiographic and tissue biomarkers of ischemia. Prehospital neuroprotection has become a reality and may be combined with revascularization therapies. Recent studies confirm that image-guided thrombolysis may be achieved without restrictive time windows. Baseline imaging patterns may be used to predict response to therapy and serial imaging may discern recanalization and reperfusion. Advanced techniques, such as arterial spin-labeled MRI, may also report hyperperfusion associated with hemorrhagic transformation. Endovascular therapies, including novel stent retriever devices, may augment revascularization and angiographic core laboratories may define optimal reperfusion. Serial evaluation of collaterals and reperfusion may identify definitive reperfusion linked with good clinical outcome rather than imposing arbitrary definitions of effective recanalization. Reperfusion injury and hemorrhagic transformation of various types may be detailed to explain clinical outcomes. Similar approaches may be used in intracranial atherosclerosis where flow, and not the degree of luminal stenosis, is paramount. Fractional flow may now be measured with computational fluid dynamics to identify high-risk lesions that require revascularization to restore the equilibrium of antegrade and collateral perfusion. Serial perfusion imaging of such cases may also illustrate inadequate cerebral blood volume gradients that may be more informative than blood flow delay alone. In sum, the growing understanding of collateral perfusion throughout all stages of ischemic stroke provides a framework for the future of ischemic stroke

    inPractice: a practical nursing package for clinical decisions

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    This paper examines the recent development of a computer-assisted learning program-in Practice-at the School of Health Science, in the University of Wales Swansea. The project, which began in 2001, was developed in close collaboration with The Meningitis Trust, the aim being to produce a software package to increase nursing students knowledge of meningitis-related illnesses, and to enhance their decision-making and problem-solving skills by using lifelike scenarios. It incorporates two multimedia meningitis modules incorporating the use of text, film, and sound, in which students are presented with information about the illness (symptoms, treatment etc.), and are required to use their knowledge to make decisions at various key points. A general discussion of decision-making theories and CAL design principles is presented, which has provided a foundation for the main design aspects of the package. This is followed by an outline of how the program was created to promote students application of knowledge and their decision-making and problem-solving skills. Results from an evaluation questionnaire are presented. Consideration is also given as to how the program can be extended

    What mechanisms dominate the activity of Geminid Parent (3200) Phaethon?

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    A long-term sublimation model to explain how Phaethon could provide the Geminid stream is proposed. We find that it would take 6\sim6 Myr or more for Phaethon to lose all of its internal ice (if ever there was) in its present orbit. Thus, if the asteroid moved from the region of a 5:2 or 8:3 mean motion resonance with Jupiter to its present orbit less than 11 Myr ago, it may have retained much of its primordial ice. The dust mantle on the sublimating body should have a thickness of at least 1515 m but the mantle could have been less than 11 m thick 10001000 years ago. We find that the total gas production rate could have been as large as 1027 s110^{27}\rm~s^{-1} then, and the gas flow could have been capable of lifting dust particles of up to a few centimeters in size. Therefore, gas production during the past millennium could have been sufficient to blow away enough dust particles to explain the entire Geminid stream. For present-day Phaethon, the gas production is comparatively weak. But strong transient gas release with a rate of 4.5×1019 m2s1\sim4.5\times10^{19}\rm~m^{-2}s^{-1} is expected for its south polar region when Phaethon moves from 00^\circ to 22^\circ mean anomaly near perihelion. Consequently, dust particles with radii of <260 μm<\sim260~\mu m can be blown away to form a dust tail. In addition, we find that the large surface temperature variation of >600>600 K near perihelion can generate sufficiently large thermal stress to cause fracture of rocks or boulders and provide an efficient mechanism to produce dust particles on the surface. The time scale for this process should be several times longer than the seasonal thermal cycle, thereby dominating the cycle of appearance of the dust tail.Comment: 10 pages, 5 figures, Accepted for publication in Monthly Notices of the Royal Astronomical Societ
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