381 research outputs found

    Rapid convergence of time-averaged frequency in phase synchronized systems

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    Numerical and experimental evidence is presented to show that many phase synchronized systems of non-identical chaotic oscillators, where the chaotic state is reached through a period-doubling cascade, show rapid convergence of the time-averaged frequency. The speed of convergence toward the natural frequency scales as the inverse of the measurement period. The results also suggest an explanation for why such chaotic oscillators can be phase synchronized.Comment: 6 pages, 9 figure

    The Local Bubble and Interstellar Material Near the Sun

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    The properties of interstellar matter (ISM) at the Sun are regulated by our location with respect to the Local Bubble (LB) void in the ISM. The LB is bounded by associations of massive stars and fossil supernovae that have disrupted natal ISM and driven intermediate velocity ISM into the LB interior void. The Sun is located in such a driven ISM parcel. The Local Fluff has a bulk velocity of 19 km/s in the LSR, and an upwind direction towards the center of the gas and dust ring formed by the Loop I supernova remnant interaction with the LB. When the ram pressure of the LIC is included in the total LIC pressure, and if magnetic thermal and cosmic ray pressures are similar, the LIC appears to be in pressure equilibrium with the local hot bubble plasma.Comment: Proceedings of Symposium on the Composition of Matter, honoring Johannes Geiss on the occasion of his 80th birthday. Space Science Reviews (in press

    Intracoronary gamma-radiation therapy after angioplasty inhibits recurrence in patients with in-stent restenosis

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    BACKGROUND: Treatment of in-stent restenosis presents a critical limitation of intracoronary stent implantation. Ionizing radiation has been shown to decrease neointimal formation within stents in animal models and in initial clinical trials. We studied the effects of intracoronary gamma-radiation therapy versus placebo on the clinical and angiographic outcomes of patients with in-stent restenosis. METHODS AND RESULTS: One hundred thirty patients with in-stent restenosis underwent successful coronary intervention and were then blindly randomized to receive either intracoronary gamma-radiation with (192)Ir (15 Gy) or placebo. Four independent core laboratories blinded to the treatment protocol analyzed the angiographic and intravascular ultrasound end points of restenosis. Procedural success and in-hospital and 30-day complications were similar among the groups. At 6 months, patients assigned to radiation therapy required less target lesion revascularization and target vessel revascularization (9 [13.8%] and 17 [26.2%], respectively) compared with patients assigned to placebo (41 [63.1%, P=0.0001] and 44 [67.7%, P=0.0001], respectively). Binary angiographic restenosis was lower in the irradiated group (19% versus 58% for placebo, P=0.001). Freedom from major cardiac events was lower in the radiation group (29.2% versus 67.7% for placebo, P<0.001). CONCLUSIONS: Intracoronary gamma-radiation used as adjunct therapy for patients with in-stent restenosis significantly reduces both angiographic and clinical restenosis

    Transforming data by calculation

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    Thispaperaddressesthefoundationsofdata-modeltransformation.A catalog of data mappings is presented which includes abstraction and representa- tion relations and associated constraints. These are justified in an algebraic style via the pointfree-transform, a technique whereby predicates are lifted to binary relation terms (of the algebra of programming) in a two-level style encompassing both data and operations. This approach to data calculation, which also includes transformation of recursive data models into “flat” database schemes, is offered as alternative to standard database design from abstract models. The calculus is also used to establish a link between the proposed transformational style and bidi- rectional lenses developed in the context of the classical view-update problem.Fundação para a Ciência e a Tecnologia (FCT

    Practicing Imperfect Forgiveness

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    Forgiveness is typically regarded as a good thing - even a virtue - but acts of forgiveness can vary widely in value, depending on their context and motivation. Faced with this variation, philosophers have tended to reinforce everyday concepts of forgiveness with strict sets of conditions, creating ideals or paradigms of forgiveness. These are meant to distinguish good or praiseworthy instances of forgiveness from problematic instances and, in particular, to protect the self-respect of would-be forgivers. But paradigmatic forgiveness is problematic for a number of reasons, including its inattention to forgiveness as a gendered trait. We can account for the values and the risks associated with forgiving far better if we treat it as a moral practice and not an ideal

    Enhancing studies of the connectome in autism using the autism brain imaging data exchange II

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    The second iteration of the Autism Brain Imaging Data Exchange (ABIDE II) aims to enhance the scope of brain connectomics research in Autism Spectrum Disorder (ASD). Consistent with the initial ABIDE effort (ABIDE I), that released 1112 datasets in 2012, this new multisite open-data resource is an aggregate of resting state functional magnetic resonance imaging (MRI) and corresponding structural MRI and phenotypic datasets. ABIDE II includes datasets from an additional 487 individuals with ASD and 557 controls previously collected across 16 international institutions. The combination of ABIDE I and ABIDE II provides investigators with 2156 unique cross-sectional datasets allowing selection of samples for discovery and/or replication. This sample size can also facilitate the identification of neurobiological subgroups, as well as preliminary examinations of sex differences in ASD. Additionally, ABIDE II includes a range of psychiatric variables to inform our understanding of the neural correlates of co-occurring psychopathology; 284 diffusion imaging datasets are also included. It is anticipated that these enhancements will contribute to unraveling key sources of ASD heterogeneity

    Velocity-space sensitivity of the time-of-flight neutron spectrometer at JET

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    The velocity-space sensitivities of fast-ion diagnostics are often described by so-called weight functions. Recently, we formulated weight functions showing the velocity-space sensitivity of the often dominant beam-target part of neutron energy spectra. These weight functions for neutron emission spectrometry (NES) are independent of the particular NES diagnostic. Here we apply these NES weight functions to the time-of-flight spectrometer TOFOR at JET. By taking the instrumental response function of TOFOR into account, we calculate time-of-flight NES weight functions that enable us to directly determine the velocity-space sensitivity of a given part of a measured time-of-flight spectrum from TOFOR

    On the mechanisms governing gas penetration into a tokamak plasma during a massive gas injection

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    A new 1D radial fluid code, IMAGINE, is used to simulate the penetration of gas into a tokamak plasma during a massive gas injection (MGI). The main result is that the gas is in general strongly braked as it reaches the plasma, due to mechanisms related to charge exchange and (to a smaller extent) recombination. As a result, only a fraction of the gas penetrates into the plasma. Also, a shock wave is created in the gas which propagates away from the plasma, braking and compressing the incoming gas. Simulation results are quantitatively consistent, at least in terms of orders of magnitude, with experimental data for a D 2 MGI into a JET Ohmic plasma. Simulations of MGI into the background plasma surrounding a runaway electron beam show that if the background electron density is too high, the gas may not penetrate, suggesting a possible explanation for the recent results of Reux et al in JET (2015 Nucl. Fusion 55 093013)
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