12,367 research outputs found

    A Three-Pole Substrate Integrated Waveguide Bandpass Filter Using New Coupling Scheme

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    A novel three-pole substrate integrated waveguide (SIW) bandpass filter (BPF) using new coupling scheme is proposed in this paper. Two high order degenerate modes (TE102 and TE201) of a square SIW cavity and a dominant mode (TE101) of a rectangular SIW cavity are coupled to form a three-pole SIW BPF. The coupling scheme of the structure is given and analyzed. Due to the coupling between two cavities, as well as the coupling between source and load, three transmission zeros are created in the stopband of the filter. The proposed three-pole SIW BPF is designed and fabricated. Good agreement between simulated and measured results verifies the validity of the design methodology well

    Wilson ratio of Fermi gases in one dimension

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    We calculate the Wilson ratio of the one-dimensional Fermi gas with spin imbalance. The Wilson ratio of attractively interacting fermions is solely determined by the density stiffness and sound velocity of pairs and of excess fermions for the two-component Tomonaga-Luttinger liquid (TLL) phase. The ratio exhibits anomalous enhancement at the two critical points due to the sudden change in the density of states. Despite a breakdown of the quasiparticle description in one dimension, two important features of the Fermi liquid are retained, namely the specific heat is linearly proportional to temperature whereas the susceptibility is independent of temperature. In contrast to the phenomenological TLL parameter, the Wilson ratio provides a powerful parameter for testing universal quantum liquids of interacting fermions in one, two and three dimensions.Comment: 5+2 pages, 4+1 figures, Eq. (4) is proved, figures were refine

    Universal local pair correlations of Lieb-Liniger bosons at quantum criticality

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    The one-dimensional Lieb-Liniger Bose gas is a prototypical many-body system featuring universal Tomonaga-Luttinger liquid (TLL) physics and free fermion quantum criticality. We analytically calculate finite temperature local pair correlations for the strong coupling Bose gas at quantum criticality using the polylog function in the framework of the Yang-Yang thermodynamic equations. We show that the local pair correlation has the universal value g(2)(0)2p/(nε)g^{(2)}(0)\approx 2 p/(n\varepsilon) in the quantum critical regime, the TLL phase and the quasi-classical region, where pp is the pressure per unit length rescaled by the interaction energy ε=22mc2\varepsilon=\frac{\hbar^2}{2m} c^2 with interaction strength cc and linear density nn. This suggests the possibility to test finite temperature local pair correlations for the TLL in the relativistic dispersion regime and to probe quantum criticality with the local correlations beyond the TLL phase. Furthermore, thermodynamic properties at high temperatures are obtained by both high temperature and virial expansion of the Yang-Yang thermodynamic equation.Comment: 8 pages, 6 figures, additional text and reference

    Bileptons from Muon Collider Backward Scattering

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    There are serious discussions for building a muon collider with μ+μ\mu^{+}\mu^{-} collisions at c.o.m. energies up to 4 TeV. We point out that the bileptonic gauge bosons predicted in some extensions of the Standard Model would be readily discernable from the backward scattering cross-section, for bilepton masses up to a substantial fraction of the c.o.m. energy.Comment: 10 pages Revtex. 4 figures include

    Phased Array Systems in Silicon

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    Phased array systems, a special case of MIMO systems, take advantage of spatial directivity and array gain to increase spectral efficiency. Implementing a phased array system at high frequency in a commercial silicon process technology presents several challenges. This article focuses on the architectural and circuit-level trade-offs involved in the design of the first silicon-based fully integrated phased array system operating at 24 GHz. The details of some of the important circuit building blocks are also discussed. The measured results demonstrate the feasibility of using integrated phased arrays for wireless communication and vehicular radar applications at 24 GHz

    Magnetic Phase Transitions in One-dimensional Strongly Attractive Three-Component Ultracold Fermions

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    We investigate the nature of trions, pairing and quantum phase transitions in one-dimensional strongly attractive three-component ultracold fermions in external fields. Exact results for the groundstate energy, critical fields, magnetization and phase diagrams are obtained analytically from the Bethe ansatz solutions. Driven by Zeeman splitting, the system shows exotic phases of trions, bound pairs, a normal Fermi liquid and four mixtures of these states. Particularly, a smooth phase transition from a trionic phase into a pairing phase occurs as the highest hyperfine level separates from the two lower energy levels. In contrast, there is a smooth phase transition from the trionic phase into a normal Fermi liquid as the lowest level separates from the two higher levels.Comment: 4 pages, 3 figures, minor revisions to text, replacement figure, refs added and update

    KDM2B/FBXL10 targets c-Fos for ubiquitylation and degradation in response to mitogenic stimulation.

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    KDM2B (also known as FBXL10) controls stem cell self-renewal, somatic cell reprogramming and senescence, and tumorigenesis. KDM2B contains multiple functional domains, including a JmjC domain that catalyzes H3K36 demethylation and a CxxC zinc-finger that recognizes CpG islands and recruits the polycomb repressive complex 1. Here, we report that KDM2B, via its F-box domain, functions as a subunit of the CUL1-RING ubiquitin ligase (CRL1/SCF(KDM2B)) complex. KDM2B targets c-Fos for polyubiquitylation and regulates c-Fos protein levels. Unlike the phosphorylation of other SCF (SKP1-CUL1-F-box)/CRL1 substrates that promotes substrates binding to F-box, epidermal growth factor (EGF)-induced c-Fos S374 phosphorylation dissociates c-Fos from KDM2B and stabilizes c-Fos protein. Non-phosphorylatable and phosphomimetic mutations at S374 result in c-Fos protein which cannot be induced by EGF or accumulates constitutively and lead to decreased or increased cell proliferation, respectively. Multiple tumor-derived KDM2B mutations impaired the function of KDM2B to target c-Fos degradation and to suppress cell proliferation. These results reveal a novel function of KDM2B in the negative regulation of cell proliferation by assembling an E3 ligase to targeting c-Fos protein degradation that is antagonized by mitogenic stimulations

    Optimization of mycelium biomass and exopolysaccharides production by Hirsutella sp. in submerged fermentation and evaluation of exopolysaccharides antibacterial activity

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    Hirsutella is a hyphomycete that has been used as biopesticide. Many compounds with antimycobacterial activity have been reported. However, there were fewer reports about fermentation condition for the Hirsutella and activity of its exopolysaccharides. In the present investigation, thefermentation condition and medium for mycelia growth and exopolysaccharides production were optimized and the antibacterial activity of exopolysaccharides (EPS) from Hirsutella sp. was studied. The optimized conditions and medium were as follows: initial pH 5.5, potato extract 20% (w/v), sucrose 2.5%, peptone 0.5%, K2HPO4 0.2%, MgSO4 0.05% and fermentation for 4 days. The highest production of EPS and mycelium biomass yield reached 2.17 and 10.06 g/l, respectively. The content of sugar and protein of EPS were 92.7 and 5.2%, respectively. The monosaccharide component of EPS was mannose, galactose and glucose with a molar ratio of 4.0:8.2:1.0. Its molecular weight was 23 kDa. Theantibacterial effect of EPS was observed that they were most effective against gram-positive bacterium, especially Bacillus subtilis and Micrococcus tetragenus. The MIC of exopolysaccharides to B. subtilisand M. tetragenus was 1 and 2.5 mg/ml, respectively. These results are helpful to expand the application of Hirsutella sp. as a biological pesticide

    Specific heat and thermal conductivity of ferromagnetic magnons in Yttrium Iron Garnet

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    The specific heat and thermal conductivity of the insulating ferrimagnet Y3_3Fe5_5O12_{12} (Yttrium Iron Garnet, YIG) single crystal were measured down to 50 mK. The ferromagnetic magnon specific heat CCm_m shows a characteristic T1.5T^{1.5} dependence down to 0.77 K. Below 0.77 K, a downward deviation is observed, which is attributed to the magnetic dipole-dipole interaction with typical magnitude of 104^{-4} eV. The ferromagnetic magnon thermal conductivity κm\kappa_m does not show the characteristic T2T^2 dependence below 0.8 K. To fit the κm\kappa_m data, both magnetic defect scattering effect and dipole-dipole interaction are taken into account. These results complete our understanding of the thermodynamic and thermal transport properties of the low-lying ferromagnetic magnons.Comment: 5 pages, 5 figure
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