402 research outputs found

    Finite-difference distributions for the Ginibre ensemble

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    The Ginibre ensemble of complex random matrices is studied. The complex valued random variable of second difference of complex energy levels is defined. For the N=3 dimensional ensemble are calculated distributions of second difference, of real and imaginary parts of second difference, as well as of its radius and of its argument (angle). For the generic N-dimensional Ginibre ensemble an exact analytical formula for second difference's distribution is derived. The comparison with real valued random variable of second difference of adjacent real valued energy levels for Gaussian orthogonal, unitary, and symplectic, ensemble of random matrices as well as for Poisson ensemble is provided.Comment: 8 pages, a number of small changes in the tex

    Particle-in-cell Simulation Concerning Heat-flux Mitigation Using Electromagnetic Fields

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    The Particle-in-Cell (PIC) method was used to study heat flux mitigation experiments with argon. In the experiment it was shown that a magnetic field allows to reduce the heat flux towards a target. PIC is well-suited for plasma simulation, giving the chance to get a better basic understanding of the underlying physics. The simulation demonstrates the importance of a self-consistent neutral-plasma description to understand the effect of heat flux reduction

    Solutioin of Poisson's Equation in Electrostatic Particle-on-cell Simulation

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    In electrostatic Particle-in-Cell simulations of the HEMP-DM3a ion thruster the role of different solution strategies for Poisson?s equation was investigated. The direct solution method of LU decomposition is compared to a stationary iterative method, the successive over-relaxation solver. Results and runtime of solvers were compared, and an outlook on further improvements and developments is presented

    Influence of Electron Sources on the Near-field Plume in a Multistage Plasma Thruster

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    n order to obtain a better understanding of the near-field plume of a multistage plasma thruster, the influence of an external electron source is investigated by Particle-In-Cell simulations. The variation of the source position showed a strong influence of the magnetic field configuration on the electron distribution and therefore on the plume plasma. In the second part of this work, higher energetic electrons were injected in order to model collision-induced diffusion in the plume. This broadens the electron distribution, which leads to a more pronounced divergence angle in the angular ion distribution

    Atmospheric energy spectra in global kilometre-scale models

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    Eleven 40-day long integrations of five different global models with horizontal resolutions of less than 9 km are compared in terms of their global energy spectra. The method of normal-mode function decomposition is used to distinguish between balanced (Rossby wave; RW) and unbalanced (inertia-gravity wave; IGW) circulation. The simulations produce the expected canonical shape of the spectra, but their spectral slopes at mesoscales, and the zonal scale at which RW and IGW spectra intersect differ significantly. The partitioning of total wave energies into RWs an IGWs is most sensitive to the turbulence closure scheme and this partitioning is what determines the spectral crossing scale in the simulations, which differs by a factor of up to two. It implies that care must be taken when using simple spatial filtering to compare gravity wave phenomena in storm-resolving simulations, even when the model horizontal resolutions are similar. In contrast to the energy partitioning between the RWs and IGWs, changes in turbulence closure schemes do not seem to strongly affect spectral slopes, which only exhibit major differences at mesoscales. Despite their minor contribution to the global (horizontal kinetic plus potential available) energy, small scales are important for driving the global mean circulation. Our results support the conclusions of previous studies that the strength of convection is a relevant factor for explaining discrepancies in the energies at small scales. The models studied here produce the major large-scale features of tropical precipitation patterns. However, particularly at large horizontal wavenumbers, the spectra of upper tropospheric vertical velocity, which is a good indicator for the strength of deep convection, differ by factors of three or more in energy. High vertical kinetic energies at small scales are mostly found in those models that do not use any convective parameterisation

    Safety and efficacy of parsaclisib in combination with obinutuzumab and bendamustine in patients with relapsed or refractory follicular lymphoma (CITADEL-102): A phase 1 study

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    Parsaclisib is a potent and highly selective PI3Kδ inhibitor that has shown clinical benefit with monotherapy in a phase 2 study in relapsed or refractory (R/R) follicular lymphoma (FL). CITADEL-102 (NCT03039114), a phase 1, multicenter study, assessed the efficacy of parsaclisib in combination with obinutuzumab and bendamustine in patients with R/R FL. Patients were ≥18 years of age with histologically confirmed and documented CD20-positive FL, and R/R to previous rituximab-containing treatment regimens. Part one (safety run-in) determined the maximum tolerated dose of parsaclisib in combination with standard dosage regimens of obinutuzumab and bendamustine. Part two (dose expansion) was an open-label, single-group design evaluating safety, tolerability (primary endpoint), and efficacy (secondary endpoint) of parsaclisib combination therapy. Twenty-six patients were enrolled in CITADEL-102 and all patients received parsaclisib 20 mg once daily for 8 weeks, followed by 20 mg once weekly thereafter, in combination with obinutuzumab and bendamustine. One patient in safety run-in experienced a dose-limiting toxicity of grade 4 QT interval prolongation that was considered related to parsaclisib. Eight patients (30.8%) discontinued treatment due to treatment-emergent adverse events (TEAEs) of colitis (2 [7.7%]), alanine aminotransferase and aspartate aminotransferase increase (both in one patient [3.8%]), neutropenia, thrombocytopenia, QT prolongation, tonsil cancer, and maculopapular rash (each 1 [3.8%]). The most common reported TEAEs were pyrexia (53.8%), neutropenia (50.0%), and diarrhea (46.2%). Twenty-three patients (88.5%) experienced grade 3 or 4 TEAEs; the most common were neutropenia (34.6%), febrile neutropenia (23.1%), and thrombocytopenia (19.2%). Seventeen patients (65.4%) had a complete response and 3 patients (11.5%) had a partial response, for an objective response rate of 76.9%. Overall, results from CITADEL-102 suggest that the combination of parsaclisib with obinutuzumab and bendamustine did not result in unexpected safety events, with little evidence of synergistic toxicity, and demonstrated preliminary efficacy in patients with R/R FL who progressed following prior rituximab-containing regimens

    Probing black hole accretion tracks, scaling relations, and radiative efficiencies from stacked X-ray active galactic nuclei

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    The masses of supermassive black holes at the centres of local galaxies appear to be tightly correlated with the mass and velocity dispersions of their galactic hosts. However, the local Mbh–Mstar relation inferred from dynamically measured inactive black holes is up to an order-of-magnitude higher than some estimates from active black holes, and recent work suggests that this discrepancy arises from selection bias on the sample of dynamical black hole mass measurements. In this work, we combine X-ray measurements of the mean black hole accretion luminosity as a function of stellar mass and redshift with empirical models of galaxy stellar mass growth, integrating over time to predict the evolving Mbh–Mstar relation. The implied relation is nearly independent of redshift, indicating that stellar and black hole masses grow, on average, at similar rates. Matching the de-biased local Mbh–Mstar relation requires a mean radiative efficiency ε ≳ 0.15, in line with theoretical expectations for accretion on to spinning black holes. However, matching the ‘raw’ observed relation for inactive black holes requires ε ∼ 0.02, far below theoretical expectations. This result provides independent evidence for selection bias in dynamically estimated black hole masses, a conclusion that is robust to uncertainties in bolometric corrections, obscured active black hole fractions, and kinetic accretion efficiency. For our fiducial assumptions, they favour moderate-to-rapid spins of typical supermassive black holes, to achieve ε ∼ 0.12–0.20. Our approach has similarities to the classic Soltan analysis, but by using galaxy-based data instead of integrated quantities we are able to focus on regimes where observational uncertainties are minimized
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