1,861 research outputs found

    Equilibrium vortex formation in ultrarapidly rotating two-component Bose-Einstein condensates

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    Equilibrium vortex formation in rotating binary Bose gases with a rotating frequency higher than the harmonic trapping frequency is investigated theoretically. We consider the system being evaporatively cooled to form condensates and a combined numerical scheme is applied to ensure the binary system being in an authentic equilibrium state. To keep the system stable against the large centrifugal force of ultrafast rotation, a quartic trapping potential is added to the existing harmonic part. Using the Thomas-Fermi approximation, a critical rotating frequency \Omega_c is derived, which characterizes the structure with or without a central density hole. Vortex structures are studied in detail with rotation frequency both above and below ?\Omega_c and with respect to the miscible, symmetrically separated, and asymmetrically separated phases in their nonrotating ground-state counterparts.Comment: 7 pages, 7 figure

    Systematic errors in strong gravitational lensing reconstructions, a numerical simulation perspective

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    We present the analysis of a sample of twenty-four SLACS-like galaxy-galaxy strong gravitational lens systems with a background source and deflectors from the Illustris-1 simulation. We study the degeneracy between the complex mass distribution of the lenses, substructures, the surface brightness distribution of the sources, and the time delays. Using a novel inference framework based on Approximate Bayesian Computation, we find that for all the considered lens systems, an elliptical and cored power-law mass density distribution provides a good fit to the data. However, the presence of cores in the simulated lenses affects most reconstructions in the form of a Source Position Transformation. The latter leads to a systematic underestimation of the source sizes by 50 per cent on average, and a fractional error in H0H_{0} of around 2519+3725_{-19}^{+37} per cent. The analysis of a control sample of twenty-four lens systems, for which we have perfect knowledge about the shape of the lensing potential, leads to a fractional error on H0H_{0} of 123+612_{-3}^{+6} per cent. We find no degeneracy between complexity in the lensing potential and the inferred amount of substructures. We recover an average total projected mass fraction in substructures of fsub<1.72.0×103f_{\rm sub}<1.7-2.0\times10^{-3} at the 68 per cent confidence level in agreement with zero and the fact that all substructures had been removed from the simulation. Our work highlights the need for higher-resolution simulations to quantify the lensing effect of more realistic galactic potentials better, and that additional observational constraint may be required to break existing degeneracies.Comment: Accepted by MNRA

    Spontaneous Crystallization of Skyrmions and Fractional Vortices in the Fast-rotating and Rapidly-quenched Spin-1 Bose-Einstein Condensates

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    We investigate the spontaneous generation of crystallized topological defects via the combining effects of fast rotation and rapid thermal quench on the spin-1 Bose-Einstein condensates. By solving the stochastic projected Gross-Pitaevskii equation, we show that, when the system reaches equilibrium, a hexagonal lattice of skyrmions, and a square lattice of half-quantized vortices can be formed in a ferromagnetic and antiferromagnetic spinor BEC, respetively, which can be imaged by using the polarization-dependent phase-contrast method

    Pathological complete response after neoadjuvant chemotherapy with trastuzumab-containing regimen in gastric cancer: a case report

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    We report a 49-year-old Chinese male with locally advanced gastric adenocarcinoma achieving pathological complete response after neoadjuvant chemotherapy with trastuzumab-containing regimen. He underwent esophagogastroduodenoscopy in September 2009, which revealed a 2-cm gastric ulcer on the lesser curvature proximal to angularis. Biopsy of gastric ulcer showed moderately differentiated adenocarcinoma with overexpression of human epidermal growth factor receptor 2 (HER2) by immunohistochemistry and fluorescence in situ hybridization. Further workups with endoscopic ultrasound, computed tomography and positron emission tomography staged his cancer as T3N1M0. He received 3 cycles of neoadjuvant chemotherapy consisting of trastuzumab, oxaliplatin, docetaxel and capecitabine without severe toxicities except grade 2 diarrhea near the completion of cycle 3 requiring discontinuation of capecitabine. Afterwards, he received total gastrectomy with extended D2 lymph node dissections showing pathological complete response. He went on to receive 3 more cycles of chemotherapy postoperatively. The role of trastuzumab as a part of perioperative therapy in gastric cancer overexpressing HER2 is worth further investigation

    Sharp - VII. New constraints on the dark matter free-streaming properties and substructure abundance from gravitationally lensed quasars

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    We present an analysis of seven strongly gravitationally lensed quasars and the corresponding constraints on the properties of dark matter. Our results are derived by modelling the lensed image positions and flux-ratios using a combination of smooth macro-models and a population of low-mass haloes within the mass range of 106-109 M☉. Our lens models explicitly include higher order complexity in the form of stellar discs and luminous satellites, as well as low-mass haloes located along the observed lines of sight for the first time. Assuming a cold dark matter (CDM) cosmology, we infer an average total mass fraction in substructure of fsub = 0.012+−00007004 (68 per cent confidence limits), which is in agreement with the predictions from CDM hydrodynamical simulations to within 1σ. This result is closer to the predictions than those from previous studies that did not include line-of-sight haloes. Under the assumption of a thermal relic dark matter model, we derive a lower limit on the particle relic mass of mth &gt; 5.58 keV (95 per cent confidence limits), which is consistent with a value of mth &gt; 5.3 keV from the recent analysis of the Ly α forest. We also identify two main sources of possible systematic errors and conclude that deeper investigations in the complex structure of lens galaxies as well as the size of the background sources should be a priority for this field

    Activation of the Syk tyrosine kinase is insufficient for downstream signal transduction in B lymphocytes

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    BACKGROUND: Immature B lymphocytes and certain B cell lymphomas undergo apoptotic cell death following activation of the B cell antigen receptor (BCR) signal transduction pathway. Several biochemical changes occur in response to BCR engagement, including activation of the Syk tyrosine kinase. Although Syk activation appears to be necessary for some downstream biochemical and cellular responses, the signaling events that precede Syk activation remain ill defined. In addition, the requirements for complete activation of the Syk-dependent signaling step remain to be elucidated. RESULTS: A mutant form of Syk carrying a combination of a K395A substitution in the kinase domain and substitutions of three phenylalanines (3F) for the three C-terminal tyrosines was expressed in a murine B cell lymphoma cell line, BCL(1).3B3 to interfere with normal Syk regulation as a means to examine the Syk activation step in BCR signaling. Introduction of this kinase-inactive mutant led to the constitutive activation of the endogenous wildtype Syk enzyme in the absence of receptor engagement through a 'dominant-positive' effect. Under these conditions, Syk kinase activation occurred in the absence of phosphorylation on Syk tyrosine residues. Although Syk appears to be required for BCR-induced apoptosis in several systems, no increase in spontaneous cell death was observed in these cells. Surprisingly, although the endogenous Syk kinase was enzymatically active, no enhancement in the phosphorylation of cytoplasmic proteins, including phospholipase Cγ2 (PLCγ2), a direct Syk target, was observed. CONCLUSION: These data indicate that activation of Syk kinase enzymatic activity is insufficient for Syk-dependent signal transduction. This observation suggests that other events are required for efficient signaling. We speculate that localization of the active enzyme to a receptor complex specifically assembled for signal transduction may be the missing event
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