769 research outputs found

    Void-induced cross slip of screw dislocations in fcc copper

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    Pinning interaction between a screw dislocation and a void in fcc copper is investigated by means of molecular dynamics simulation. A screw dislocation bows out to undergo depinning on the original glide plane at low temperatures, where the behavior of the depinning stress is consistent with that obtained by a continuum model. If the temperature is higher than 300 K, the motion of a screw dislocation is no longer restricted to a single glide plane due to cross slip on the void surface. Several depinning mechanisms that involve multiple glide planes are found. In particular, a depinning mechanism that produces an intrinsic prismatic loop is found. We show that these complex depinning mechanisms significantly increase the depinning stress

    Spectral flow of non-hermitian Heisenberg spin chain with complex twist

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    We investigate the spectral flow of the integrable non-hermitian Heisenberg spin chain under boundary conditions with complex twist angle. It is shown that the period of the spectral flow is 4Ï€4\pi up to a certain critical imaginary twist, beyond which the period jumps successively to higher values. We argue that this phenomenon caused by non-hermitian properties of the system is closely related to the metal-insulator transition caused by non-hermitian hoppings for the one-dimensional insulator.Comment: 10 pages, revtex, to appear in NP

    Periodic Oscillations of Josephson-Vortex Flow Resistance in Oxygen-Deficient Y1Ba2Cu3Ox

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    We measured the Josephson vortex flow resistance as a function of magnetic field applied parallel to the ab-planes using annealed Y1Ba2Cu3Ox intrinsic Josephson junctions having high anisotropy (around 40) by oxygen content reduction. Periodic oscillations were observed in magnetic fields above 45-58 kOe, corresponding to dense-dilute boundary for Josephson vortex lattice. The observed period of oscillations, agrees well with the increase of one fluxon per two junctions (HpH_{p}\textit{=Φ\Phi }0_{0}\textit{/2Ls}), may correspond to formation of a triangular lattice of Josephson vortices as has been reported by Ooi et al. for highly anisotropic (larger than 200) Bi-2212 intrinsic Josephson junctions.Comment: 5 pages, 4 figure

    Recent developments and future directions of first-line systemic therapy combined with immunotherapy for advanced or metastatic urothelial carcinoma: a historical perspective on treatment evolution

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    The version of record of this article, first published in International Journal of Clinical Oncology, is available online at Publisher’s website: https://doi.org/10.1007/s10147-024-02526-y.Urothelial carcinoma presents significant treatment challenges, especially in advanced stages. Traditionally managed with platinum-based chemotherapy, the advent of immunotherapies, particularly immune checkpoint inhibitors, has revolutionized urothelial carcinoma treatment. This review explores the evolution of urothelial carcinoma management, focusing on the transition from immune checkpoint inhibitors monotherapy to innovative combination therapies. Pembrolizumab, following the KEYNOTE-045 trial, emerged as a pivotal ICI in pretreated metastatic urothelial carcinoma, outperforming traditional chemotherapy. However, limitations surfaced in untreated metastatic urothelial carcinoma patients, particularly in those with low PD-L1 expression, as evidenced by trials like IMvigor130 and KEYNOTE-361. These challenges led to the exploration of combination therapies, including immune checkpoint inhibitors with platinum-based chemotherapy, tyrosine kinase inhibitors, and antibody–drug conjugates. Notably, the CheckMate 901 trial demonstrated improved outcomes with a nivolumab–chemotherapy combination. A significant breakthrough was achieved with the combination of enfortumab vedotin, an antibody–drug conjugates, and pembrolizumab, setting a new standard in first-line treatment for locally advanced or metastatic urothelial carcinoma. Future directions involve further exploration of antibody–drug conjugates and immune checkpoint inhibitors, as seen in the TROPHY-U-01 and TROPiCS-4 trials. The review concludes that the locally advanced or metastatic urothelial carcinoma treatment landscape is rapidly evolving, with combination therapies offering promising avenues for improved patient outcomes, signaling a new era in urothelial carcinoma management

    Transient Gamma Ray Spectrometer Measurements of Gamma-Ray Lines from Novae. I. Limits on the Positron Annihilation Line in Five Individual Novae

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    The Transient Gamma Ray Spectrometer (TGRS) on board the WIND spacecraft has spent most of the interval 1995-1997 in a high-altitude orbit where gamma-ray backgrounds are low. Its high-resolution Ge spectrometer is thus able to detect weak lines which are slightly offset from stronger background features. One such line is predicted from nucleosynthesis in classical novae, where beta-decays on a time-scale of a few hours in an expanding envelope produce positrons that annihilate to generate a line which is blueshifted by a few keV away from the background annihilation line at 511 keV. The broad TGRS field of view contained five known Galactic novae during 1995 January - 1997 June, and we have searched the spectra taken around the times of these events for the blueshifted nova annihilation line. Although no definite detections were made, the method is shown to be sensitive enough to detect novae occurring on ONeMg-rich white dwarfs out to about 2.5 kpc.Comment: 27 pp. + 10 figs., or offprint mailed by request to [email protected]

    FLOW BEHAVIORS IN A HIGH SOLID FLUX CIRCULATING FLUIDIZED BED COMPOSED OF A RISER, A DOWNER AND A BUBBLING FLUIDIZED BED

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    A circulating fluidized bed coal gasifier cold model which consists of an acrylic riser, a downer, and a bubbling fluidized bed were set up. Flow behaviors were investigated using silica sand with the solid mass flux up to 336 kg/m2•s. The effects of the solid inventory and the seals between the three reaction zones on the solid mass flux were investigated and discussed

    Analyzing powers Ayy, Axx, Axz and Ay in the dd->3Hen reaction at 270 MeV

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    The data on the tensor Ayy, Axx, Axz and vector Ay analyzing powers in the dd->3Hen obtained at Td= 270 MeV in the angular range 0 - 110 degrees in the c.m. are presented. The observed negative sign of the tensor analyzing powers Ayy, Axx and Axz at small angles clearly demonstrate the sensitivity to the ratio of the D and S wave component of the 3He wave function. However, the one-nucleon exchange calculations by using the standard 3He wave functions have failed to reproduce the strong variation of the tensor analyzing powers as a function of the angle in the c.m.Comment: 8 pages, 7 figures, 4 tables. Submitted to EPJ

    Breakdown of the Mott insulator: Exact solution of an asymmetric Hubbard model

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    The breakdown of the Mott insulator is studied when the dissipative tunneling into the environment is introduced to the system. By exactly solving the one-dimensional asymmetric Hubbard model, we show how such a breakdown of the Mott insulator occurs. As the effect of the tunneling is increased, the Hubbard gap is monotonically decreased and finally disappears, resulting in the insulator-metal transition. We discuss the origin of this quantum phase transition in comparison with other non-Hermitian systems recently studied.Comment: 7 pages, revte
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