2,198 research outputs found

    Use of the method of particular solutions in nonlinear, two-point boundary-value problems. Part 1 - Uncontrolled systems

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    Nonlinear two-point boundary-value problem solution by combined techniques of quasilinearization and method of particular solution

    Use of the method of particular solutions in nonlinear, two-point boundary-value problems. Part 2 - Controlled systems

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    Method of particular solutions used to solve two point boundary value problem for nonlinear controlled syste

    Mathematical programming for constrained minimal problems. Part 1 - Sequential gradient, restoration algorithm

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    Algorithm using gradient and restoration phases for constrained minimal problem

    Generalization and performance improvement of a coherence multiplexing system

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    Usually a coherence multiplexing system uses delay-filters at the transmitter and receiver to perform the code. An extension to other filter types is described. Using a continuous source the signal-to-beat noise ratio is proportional to the square of the inverse of the number of simultaneous users. A further extension is made by using a pulsed source and by replacing the filters by banks of filters. Each element of each filter bank also comprizes a unique delay. In that case the SNR can be made proportional to the inverse of the number of users, so that more users can be handled simultaneously

    Conical bodies of given length and volume having maximum lift-to-drag ratio at hypersonic speeds - Direct methods

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    Lift to drag ratios of slender, conical bodies flying at hypersonic speeds, and effects of geometric parameters on aerodynamic stabilit

    Low loss, high contrast optical waveguides based on CMOS compatible LPCVD processing

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    A new class of integrated optical waveguide structures is presented, based on low cost CMOS compatible LPCVD processing. This technology allows for medium and high index contrast waveguides with very low channel attenuation. The geometry is basically formed by a rectangular cross-section silicon nitride (Si3N4)(Si_{3}N_{4}) filled with and encapsulated by silicon dioxide (SiO2)(SiO_{2}). The birefringence and minimal bend radius of the waveguide is completely controlled by the geometry of the waveguide layer structures. Experiments on typical geometries will be presented, showing excellent characteristics (channel attenuation ≤0.06 dB/cm, IL ≤0.6 dB, PDL ≤0.2 dB, Bg «1 x 10310^{-3}, bend radius ≤500 μm)

    A family of linearizable recurrences with the Laurent property

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    We consider a family of non-linear recurrences with the Laurent property. Although these recurrences are not generated by mutations in a cluster algebra, they fit within the broader framework of Laurent phenomenon algebras, as introduced recently by Lam and Pylyavskyy. Furthermore, each member of this family is shown to be linearizable in two different ways, in the sense that its iterates satisfy both a linear relation with constant coefficients and a linear relation with periodic coefficients. Associated monodromy matrices and first integrals are constructed, and the connection with the dressing chain for Schrödinger operators is also explained

    A compact and reconfigurable silicon nitride time-bin entanglement circuit

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    Photonic chip based time-bin entanglement has attracted significant attention because of its potential for quantum communication and computation. Useful time-bin entanglement systems must be able to generate, manipulate and analyze entangled photons on a photonic chip for stable, scalable and reconfigurable operation. Here we report the first time-bin entanglement photonic chip that integrates time-bin generation, wavelength demultiplexing and entanglement analysis. A two-photon interference fringe with an 88.4% visibility is measured (without subtracting any noise), indicating the high performance of the chip. Our approach, based on a silicon nitride photonic circuit, which combines the low-loss characteristic of silica and tight integration features of silicon, paves the way for scalable real-world quantum information processors.Comment: 4 pages, 5 figure

    The failure of suicide prevention in primary care: family and GP perspectives - a qualitative study

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    Background Although Primary care is crucial for suicide prevention, clinicians tend to report completed suicides in their care as non-preventable. We aimed to examine systemic inadequacies in suicide prevention from the perspectives of bereaved family members and GPs.Methods Qualitative study of 72 relatives or close friends bereaved by suicide and 19 General Practitioners who have experienced the suicide of patients.Results Relatives highlight failures in detecting symptoms and behavioral changes and the inability of GPs to understand the needs of patients and their social contexts. A perceived overreliance on anti-depressant treatment is a major source of criticism by family members. GPs tend to lack confidence in the recognition and management of suicidal patients, and report structural inadequacies in service provision.Conclusions Mental health and primary care services must find innovative and ethical ways to involve families in the decision-making process for patients at risk of suicide
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