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Search Results: 1 - 10 of 80903 matches for " Boyang Liu "
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Muonium-Antimuonium Oscillations in an extended Minimal Supersymmetric Standard Model with right-handed neutrinos
Liu, Boyang
High Energy Physics - Phenomenology , 2008, DOI: 10.1103/PhysRevD.79.015001
Abstract: The electron and muon number violating muonium-antimuonium oscillation process in an extended Minimal Supersymmetric Standard Model is investigated. The Minimal Supersymmetric Standard Model is modified by the inclusion of three right-handed neutrino superfields. While the model allows the neutrino mass terms to mix among the different generations, the sneutrino and slepton mass terms have only intra-generation lepton number violation but not inter-generation lepton number mixing. So doing, the muonium-antimuonium conversion can then be used to constrain those model parameters which avoid further constraint from the $\mu\to e\gamma$ decay bounds. For a wide range of parameter values, the contributions to the muonium-antimuonium oscillation time scale are at least two orders of magnitude below the sensivity of current experiments. However, if the ratio of the two Higgs field VEVs, $\tan\beta$, is very small, there is a limited possibility that the contributions are large enough for the present experimental limit to provide an inequality relating $\tan\beta$ with the light neutrino mass scale $m_\nu$ which is generated by see-saw mechanism. The resultant lower bound on $\tan\beta$ as a function of $m_\nu$ is more stringent than the analogous bounds arising from the muon and electron anomalous magnetic moments as computed using this model.
Research on Motion Attention Fusion Model-Based Video Target Detection and Extraction of Global Motion Scene  [PDF]
Long Liu, Boyang Fan, Jing Zhao
Journal of Signal and Information Processing (JSIP) , 2013, DOI: 10.4236/jsip.2013.43B006

For target detection algorithm under global motion scene, this paper suggests a target detection algorithm based on motion attention fusion model. Firstly, the motion vector field is pre-processed by accumulation and median filter; Then, according to the temporal and spatial character of motion vector, the attention fusion model is defined, which is used to detect moving target; Lastly, the edge of video moving target is made exactly by morphologic operation and edge tracking algorithm. The experimental results of different global motion video sequences show the proposed algorithm has a better veracity and speedup than other algorithm.

One-loop renormalization group study of boson-fermion mixtures
Boyang Liu,Jiangping Hu
Physics , 2012, DOI: 10.1142/S0217979212501974
Abstract: A weakly interacting boson-fermion mixture model was investigated using Wisonian renormalization group analysis. This model includes one boson-boson interaction term and one boson-fermion interaction term. The scaling dimensions of the two interaction coupling constants were calculated as 2-D at tree level and the Gell-Mann-Low equations were derived at one-loop level. We find that in the Gell-Mann-Low equations the contributions from the fermion loops go to zero as the length scale approaches infinity. After ignoring the fermion loop contributions two fixed points were found in 3 dimensional case. One is the Gaussian fixed point and the other one is Wilson-Fisher fixed point. We find that the boson-fermion interaction decouples at the Wilson-Fisher fixed point. We also observe that under RG transformation the boson-fermion interaction coupling constant runs to negative infinity with a small negative initial value, which indicates a boson-fermion pairing instability. Furthermore, the possibility of emergent supersymmetry in this model was discussed.
Quantum Fluctuation Driven First-order Phase Transitions in Optical Lattices
Boyang Liu,Jiangping Hu
Physics , 2013, DOI: 10.1103/PhysRevA.92.013606
Abstract: We study quantum fluctuation driven first-order phase transitions of a two-species bosonic system in a three-dimensional optical lattice. Using effective potential method we find that the superfluid-Mott insulator phase transition of one type of bosons can be changed from second-order to first-order by the quantum fluctuations of the other type of bosons. The study of the scaling behaviors near the quantum critical point shows that the first-order phase transition has a different universality from the second-order one. We also discuss the observation of this exotic phenomenon in the realistic cold-atom experiments.
An Experiment of K-Means Initialization Strategies on Handwritten Digits Dataset  [PDF]
Boyang Li
Intelligent Information Management (IIM) , 2018, DOI: 10.4236/iim.2018.102003
Abstract: Clustering is an important unsupervised classification method which divides data into different groups based some similarity metrics. K-means becomes an increasing method for clustering and is widely used in different application. Centroid initialization strategy is the key step in K-means clustering. In general, K-means has three efficient initialization strategies to improve its performance i.e., Random, K-means++ and PCA-based K-means. In this paper, we design an experiment to evaluate these three strategies on UCI ML hand-written digits dataset. The experiment result shows that the three K-means initialization strategies find out almost identical cluster centroids, and they have almost the same results of clustering, but the PCA-based K-means strategy significantly improves running time, and is faster than the other two strategies.
Quantum Phase Transition of Bosons in a Shaken Optical Lattice
Jiao Miao,Boyang Liu,Wei Zheng
Physics , 2015, DOI: 10.1103/PhysRevA.91.033404
Abstract: Recently, the lattice shaking technique has been used to couple different Bloch bands resonantly. For the one-dimensional (1D) case, in which shaking is along only one direction, experimental observation of domain-wall formation has been explained by superfluid Ising transition. Inspired by these, we generalize to a 2D case in which shaking is along two orthogonal directions. Analogous to the 1D case, we find three different phases, the normal superfluid (NSF) phase, the $D_4$ symmetry-breaking superfluid ($D_4$SF) phase and the Mott insulator (MI) phase. Furthermore, we demonstrate that the interaction effect induced by inhomogeneous band mixing can modify the critical shaking amplitude. Unlike in the 1D case, shaking types also can modify the critical shaking amplitude. Unlike in the 1D case, shaking types also can modify the critical shaking amplitude. We also construct a low-energy effective field theory to study the quantum criticality of bosons near the tricritical point of NSF, $D_4$SF and MI phases. Moreover, we find a Bose liquid with anisotropically algebraic order and propose to change the Bose-Einstein condensation (BEC) into a non-condensed Bose liquid by tuning the shaking amplitude approaching the critical value.
Evolution of Higgs mode in a Fermion Superfluid with Tunable Interactions
Boyang Liu,Hui Zhai,Shizhong Zhang
Physics , 2015,
Abstract: In this letter we present a coherent picture for the evolution of Higgs mode in both neutral and charged $s$-wave fermion superfluids, as the strength of attractive interaction between fermions increases from the BCS to the BEC regime. In the case of neutral fermionic superfluid, such as ultracold fermions, the Higgs mode is pushed to higher energy while at the same time, gradually loses its spectral weight as interaction strength increases toward the BEC regime, because the system is further tuned away from Lorentz invariance. On the other hand, when damping is taken into account, Higgs mode is significantly broadened due to coupling to phase mode in the whole BEC-BCS crossover. In the charged case of electron superconductor, the Anderson-Higgs mechanism gaps out the phase mode and suppresses the coupling between the Higgs and the phase modes, and consequently, stabilizes the Higgs mode.
Fluctuation Effects on the Transport Properties of Unitary Fermi Gases
Boyang Liu,Hui Zhai,Shizhong Zhang
Physics , 2014, DOI: 10.1103/PhysRevA.90.051602
Abstract: In this letter, we investigate the fluctuation effects on the transport properties of unitary Fermi gases in the vicinity of the superfluid transition temperature $T_c$. Based on the time-dependent Ginzburg-Landau formalism of the BEC-BCS crossover, we investigate both the residual resistivity below $T_c$ induced by phase slips and the paraconductivity above $T_c$ due to pair fluctuations. These two effects have been well studied in the weak coupling BCS superconductor, and here we generalize them to the unitary regime of ultracold Fermi gases. We find that while the residual resistivity below $T_c$ increases as one approaches the unitary limit, consistent with recent experiments, the paraconductivity exhibits non-monotonic behavior. Our results can be verified with the recently developed transport apparatus using mesoscopic channels.
Renormalization group analysis of $p$-orbital Bose-Einstein condensates in a square optical lattice
Boyang Liu,Xiao-Lu Yu,Wu-Ming Liu
Physics , 2012, DOI: 10.1103/PhysRevA.88.063605
Abstract: We investigate the quantum fluctuation effects in the vicinity of the critical point of a $p$-orbital bosonic system in a square optical lattice using Wilsonian renormalization group, where the $p$-orbital bosons condense at nonzero momenta and display rich phases including both time-reversal symmetry invariant and broken BEC states. The one-loop renormalization group analysis generates corrections to the mean-field phase boundaries. We also show the quantum fluctuations in the $p$-orbital system tend to induce the ordered phase but not destroy it via the the Coleman-Weinberg mechanism, which is qualitative different from the ordinary quantum fluctuation corrections to the mean-field phase boundaries in $s$-orbital systems. Finally we discuss the observation of these phenomena in the realistic experiment.
Generation and antitumor effects of an engineered and energized fusion protein VL-LDP-AE composed of single-domain antibody and lidamycin
QingFang Miao,BoYang Shang,ZhiGang Ouyang,XiaoYun Liu,YongSu Zhen
Science China Life Sciences , 2007, DOI: 10.1007/s11427-007-0058-5
Abstract: Type IV collagenase plays a pivotal role in invasion, metastasis and angiogenesis of tumor. Single domain antibodies are attractive as tumor-targeting vehicle because of their much smaller size compared with antibody molecules produced by conventional methods. Lidamycin (LDM) is a potent enediyne-containing antitumor antibiotic. In this study an engineered and energized fusion protein VL-LDP-AE composed of lidamycin and VL domain of mAb 3G11 directed against type IV collagenase was prepared using a novel two-step method. First a VL-LDP fusion protein was constructed by DNA recombination. Secondly VL-LDP-AE was obtained by molecular reconstitution. In MTT assay, VL-LDP-AE showed potent cytotoxicity to HT-1080 cells and KB cells with IC 50 values of 8.55×10 12 and 1.70×10 11 mol/L, respectively. VL-LDP-AE showed antiangiogenic activity in chick chrorioallantoic membrane (CAM) assay and tube formation assay. In in vivo experiments, VL-LDP-AE was proved to be more effective than free LDM against the growth of subcutaneously transplanted hepatoma 22 in mice. Drugs were given intravenously on day 3 and 10 after tumor transplantation. Compared in terms of maximal tolerated doses, VL-LDP-AE at 0.25 mg/kg suppressed the tumor growth by 89.5%, LDM at 0.05 mg/kg by 69.9%, and mitomycin at 1 mg/kg by 35%. Having a molecular weight of 25.2 kDa, VL-LDP-AE was much smaller than other reported antibody-based drugs. The results suggested that VL-LDP-AE would be a promising candidate for tumor targeting therapy. And the 2-step approach could serve as a new technology platform for making a series of highly potent engineered antibody-based drugs for a variety of cancers.
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