1,095 research outputs found

    Real-time control of divertor detachment in H-mode with impurity seeding using Langmuir probe feedback in JET-ITER-like wall

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    Burning plasmas with 500 MW of fusion power on ITER will rely on partially detached divertor operation to keep target heat loads at manageable levels. Such divertor regimes will be maintained by a real-time control system using the seeding of radiative impurities like nitrogen (N), neon or argon as actuator and one or more diagnostic signals as sensors. Recently, real-time control of divertor detachment has been successfully achieved in Type I ELMy H-mode JETITER-like wall discharges by using saturation current (Isat) measurements from divertor Langmuir probes as feedback signals to control the level of N seeding. The degree of divertor detachment is calculated in real-time by comparing the outer target peak Isat measurements to the peak Isat value at the roll-over in order to control the opening of the N injection valve. Real-time control of detachment has been achieved in both fixed and swept strike point experiments. The system has been progressively improved and can now automatically drive the divertor conditions from attached through high recycling and roll-over down to a user-defined level of detachment. Such a demonstration is a successful proof of principle in the context of future operation on ITER which will be extensively equipped with divertor target probes

    Phase IV open-label study of the efficacy and safety of deferasirox after allogeneic stem cell transplantation

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    This is the first prospective study of deferasirox in adult allogeneic hematopoietic stem cell transplant recipients with transfusional iron overload in hematologic malignancies. Patients at least six months post transplant were treated with deferasirox at a starting dose of 10 mg/kg/day for 52 weeks or until serum ferritin was less than 400 ng/mL on two consecutive occasions. Thirty patients were enrolled and 22 completed the study. A significant reduction from baseline in median serum ferritin and in liver iron concentration at 52 weeks was observed in the overall population: from 1440 to 755.5 ng/mL (P=0.002) and from 14.5 to 4.6 mg Fe/g dw (P=0.0007), respectively. Reduction in serum ferritin in patients who did not discontinue deferasirox therapy was significantly greater than that found in those who prematurely discontinued the treatment (from 1541 to 581 ng/mL vs. from 1416 to 1486 ng/mL; P=0.008). Drug-related adverse events, reported in 17 patients (56.7%), were mostly mild to moderate in severity. There were no drug-related serious adverse events. Twelve patients (40.0%) showed an increase of over 33% in serum creatinine compared to baseline and greater than the upper limit of normal on two consecutive visits. Two patients (6.7%) with active graft-versus-host disease showed an increase in alanine aminotransferase exceeding 10 times upper limit of normal; both resolved. In this prospective study, deferasirox provided a significant reduction in serum ferritin and liver iron concentration over one year of treatment in allogeneic hematopoietic stem cell transplant recipients with iron overload. In addition, the majority of adverse events related to deferasirox were mild or moderate in severity. (clinicaltrials.gov identifier:01335035)

    The number of transmission channels through a single-molecule junction

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    We calculate transmission eigenvalue distributions for Pt-benzene-Pt and Pt-butadiene-Pt junctions using realistic state-of-the-art many-body techniques. An effective field theory of interacting π\pi-electrons is used to include screening and van der Waals interactions with the metal electrodes. We find that the number of dominant transmission channels in a molecular junction is equal to the degeneracy of the molecular orbital closest to the metal Fermi level.Comment: 9 pages, 8 figure

    Interaction of two modulational instabilities in a semiconductor resonator

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    The interaction of two neighboring modulational instabilities in a coherently driven semiconductor cavity is investigated. First, an asymptotic reduction of the general equations is performed in the limit of a nearly vertical input-output characteristic. Next, a normal form is derived in the limit where the two instabilities are close to one other. An infinity of branches of periodic solutions are found to emerge from the unstable portion of the homogeneous branch. These branches have a nontrivial envelope in the bifurcation diagram that can either smoothly join the two instability points or form an isolated branch of solutions

    Phase-Locked Spatial Domains and Bloch Domain Walls in Type-II Optical Parametric Oscillators

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    We study the role of transverse spatial degrees of freedom in the dynamics of signal-idler phase locked states in type-II Optical Parametric Oscillators. Phase locking stems from signal-idler polarization coupling which arises if the cavity birefringence and/or dichroism is not matched to the nonlinear crystal birefringence. Spontaneous Bloch domain wall formation is theoretically predicted and numerically studied. Bloch walls connect, by means of a polarization transformation, homogeneous regions of self-phase locked solutions. The parameter range for their existence is analytically found. The polarization properties and the dynamics of walls in one- and two transverse spatial dimensions is explained. Transition from Bloch to Ising walls is characterized, the control parameter being the linear coupling strength. Wall dynamics governs spatiotemporal dynamical states of the system, which include transient curvature driven domain growth, persistent dynamics dominated by spiraling defects for Bloch walls, and labyrinthine pattern formation for Ising walls.Comment: 27 pages, 16 figure

    VERITAS Observations of the gamma-Ray Binary LS I +61 303

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    LS I +61 303 is one of only a few high-mass X-ray binaries currently detected at high significance in very high energy gamma-rays. The system was observed over several orbital cycles (between September 2006 and February 2007) with the VERITAS array of imaging air-Cherenkov telescopes. A signal of gamma-rays with energies above 300 GeV is found with a statistical significance of 8.4 standard deviations. The detected flux is measured to be strongly variable; the maximum flux is found during most orbital cycles at apastron. The energy spectrum for the period of maximum emission can be characterized by a power law with a photon index of Gamma=2.40+-0.16_stat+-0.2_sys and a flux above 300 GeV corresponding to 15-20% of the flux from the Crab Nebula.Comment: accepted for publication in The Astrophysical Journa
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