One dimensional model for doubly degenerate electrons

A Hubbard-like model with SU(4) symmetry for electrons with two-fold orbital degeneracy is studied extensively. Exact solution in one dimension is derived by means of Bethe ansatz, where the sites are supposed to be occupied by at most two electrons. The features of ground state and excited states for repulsive coupling are shown. For finite N number of electrons, the configurations of quantum numbers are given explicitly and the spectra of excitations are obtained by solving the Bethe-ansatz equation numerically. For infinite N, the ground state and various kinds of low-lying excitations are obtained on the basis of thermodynamics limit.Comment: Revtex, 21 pages including 9 figures, PRB versio

Numerical and Monte Carlo Bethe ansatz method: 1D Heisenberg model

In this paper we present two new numerical methods for studying thermodynamic quantities of integrable models. As an example of the effectiveness of these two approaches, results from numerical solutions of all sets of Bethe ansatz equations, for small Heisenberg chains, and Monte Carlo simulations in quasi-momentum space, for a relatively larger chains, are presented. Our results agree with those obtained by thermodynamics Bethe ansatz (TBA) and Quantum Transfer Matrix (QTM).Comment: 8 pages, 6 figure

Thermodynamics of SU(2) bosons in one dimension

On the basis of Bethe ansatz solution of two-component bosons with SU(2) symmetry and $\delta$-function interaction in one dimension, we study the thermodynamics of the system at finite temperature by using the strategy of thermodynamic Bethe ansatz (TBA). It is shown that the ground state is an isospin "ferromagnetic" state by the method of TBA, and at high temperature the magnetic property is dominated by Curie's law. We obtain the exact result of specific heat and entropy in strong coupling limit which scales like $T$ at low temperature. While in weak coupling limit, it is found there is still no Bose-Einstein Condensation (BEC) in such 1D system.Comment: 7 page

Enhancing Customer Satisfaction Analysis with a Machine Learning Approach: From a Perspective of Matching Customer Comment and Agent Note

With the booming of UGCs, customer comments are widely utilized in analyzing customer satisfaction. However, due to the characteristics of emotional expression, ambiguous semantics and short text, sentiment analysis with customer comments is easily biased and risky. This paper introduces another important UGC, i.e., agent notes, which not only effectively complements customer comment, but delivers professional details, which may enhance customer satisfaction analysis. Moreover, detecting the mismatch on aspects between these two UGCs may further help gain in-depth customer insights. This paper proposes a machine learning based matching analysis approach, namely CAMP, by which not only the semantics and sentiment in customer comments and agent notes can be sufficiently and comprehensively investigated, but the granular and fine-grained aspects could be detected. The CAMP approach can provide practical guidance for following-up service, and the automation can help speed-up service response, which essentially improves customer satisfaction and retains customer loyalty

Downlink Channel Covariance Matrix Reconstruction for FDD Massive MIMO Systems with Limited Feedback

The downlink channel covariance matrix (CCM) acquisition is the key step for the practical performance of massive multiple-input and multiple-output (MIMO) systems, including beamforming, channel tracking, and user scheduling. However, this task is challenging in the popular frequency division duplex massive MIMO systems with Type I codebook due to the limited channel information feedback. In this paper, we propose a novel formulation that leverages the structure of the codebook and feedback values for an accurate estimation of the downlink CCM. Then, we design a cutting plane algorithm to consecutively shrink the feasible set containing the downlink CCM, enabled by the careful design of pilot weighting matrices. Theoretical analysis shows that as the number of communication rounds increases, the proposed cutting plane algorithm can recover the ground-truth CCM. Numerical results are presented to demonstrate the superior performance of the proposed algorithm over the existing benchmark in CCM reconstruction

A novel multifunctional biomedical material based on polyacrylonitrile:preparation and characterization

Wet spun microfibers have great potential in the design of multifunctional controlled release materials. Curcumin (Cur) and vitamin E acetate (Vit. E Ac) were used as a model drug system to evaluate the potential application of the drug-loaded microfiber system for enhanced delivery. The drugs and polyacrylonitrile (PAN) were blended together and spun to produce the target drug-loaded microfiber using an improved wet-spinning method and then the microfibers were successfully woven into fabrics. Morphological, mechanical properties, thermal behavior, drug release performance characteristics, and cytocompatibility were determined. The drug-loaded microfiber had a lobed “kidney” shape with a height of 50 ~ 100 μm and width of 100 ~ 200 μm. The addition of Cur and Vit. E Ac had a great influence on the surface and cross section structure of the microfiber, leading to a rough surface having microvoids. X-ray diffraction and Fourier transform infrared spectroscopy indicated that the drugs were successfully encapsulated and dispersed evenly in the microfilament fiber. After drug loading, the mechanical performance of the microfilament changed, with the breaking strength improved slightly, but the tensile elongation increased significantly. Thermogravimetric results showed that the drug load had no apparent adverse effect on the thermal properties of the microfibers. However, drug release from the fiber, as determined through in-vitro experiments, is relatively low and this property is maintained over time. Furthermore, in-vitro cytocompatibility testing showed that no cytotoxicty on the L929 cells was found up to 5% and 10% respectively of the theoretical drug loading content (TDLC) of curcumin and vitamin E acetate. This study provides reference data to aid the development of multifunctional textiles and to explore their use in the biomedical material field

同型半胱氨酸对人脐静脉内皮细胞线粒体膜电位的影响

Objective:  To observe the changes of endothelial mitochondrial membrane potential（MMP）by building Hcy-induced endothelial impairment model in cultured human umbilical vein endothelial cells and to analyze the mechanism of Hcy-induced apoptosis.Methods: (1) Cultured HUVECs of term infant in vitro provide enough experimental materials. (2)The HUVECs are randomly divided into five groups: the control group does not add Hcy, the other groups add 0.01、0.1、1.0、3.0mmol/LHCY respectively, and put them together for 24 hours to detect the changes of MMP of the HUVECs at 3、6、12、24 hour.Results: There is no difference in the level of MMP in the HUVECs stimulated by HCY for 24 hours between the HCY0.01mmol/L group and the control group. Comparing with the control group,MMP reduces at 24 hour in the HCY0.1 mmol/L group ,at 6、12、24 hour in the HCY1.0 mmol/L group and at 3、6 hour(P<0.05）and obviously at 12、24 hour(P<0.01) in the HCY3.0 mmol/L group.In the same Hcy-induced group, MMP obviously reduces at 24 hour, ＞12h、6h、3h.At the same time, MMP obviously reduces at 3.0mmol/L Hcy-induced group, ＞1.0、0.1、0.01 mmol/L group and the control group.Conclusion: (1)HCY can injury endothelial function and induce apoptosis and it relates with concentration and time of HCY.(2) Mechanism of  Hcy- induced endothelial apoptosis may relates the reduction of MMP.目的 探讨同型半胱氨酸诱导人脐静脉内皮细胞线粒体膜电位(MMP)的变化，了解血管内皮细胞发生细胞凋亡的机制。方法 无菌采集正常足月剖腹产胎儿脐带进行人脐静脉内皮细胞培养，取对数生长的人脐静脉内皮细胞制成细胞悬液，加含1％胎牛血清（FCS）的培养基(DMEM)处理细胞24h，使细胞稳定、同步化。随机分成五组:（1）空白组：仅加含1％FCS的DMEM5ml。（2）HCY0.01mmol/L组：1％FCS的DMEM＋HCY终浓度为0.01 mmol/L 5ml。（3）HCY0.1 mmol/L组：1％FCS的DMEM＋HCY终浓度为0.1mmol/L 5ml。（4） HCY1.0 mmol/L组：1％FCS的DMEM＋HCY终浓度为1.0 mmol/L 5ml。（5）HCY3.0mmol/L组：1％FCS的DMEM＋HCY终浓度为3.0 mmol/L 5ml。继续培养24h，每组3个样本。结果 不9同浓度及时间HCY对HUVECs线粒体膜电位的影响:MMP在HCY0.01mmol/L组和空白对照组间无差异性变化；在HCY0.1 mmol/L组于24h时出现下降（P<0.05）；在HCY1.0mmol/L组于6h、12h、24h出现下降（P<0.05）；在HCY3.0mmol/L组于3h、6h有下降（P<0.05），12h、24h明显降低（P<0.01）。同一浓度HCY作用24h时MMP最低，依次＞12h、6h、3h。相同时间内，可以看到HCY浓度越高MMP降低越多，MMP在HCY3.0mmol/L组最低，依次＞1.0、0.1及0.01和空白组，结论 HCY可导致MMP发生改变，其浓度及作用时间是影响因素。（1）相同时间内，HCY浓度越高MMP降低越多。（2）同一浓度HCY作用时间越长MMP越低。

Quenched Charmed Meson Spectra using Tadpole Improved Quark Action on Anisotropic Lattices

Charmed meson charmonium spectra are studied with improved quark actions on anisotropic lattices. We measured the pseudo-scalar and vector meson dispersion relations for 4 lowest lattice momentum modes with quark mass values ranging from the strange quark to charm quark with 3 different values of gauge coupling $\beta$ and 4 different values of bare speed of light $\nu$. With the bare speed of light parameter $\nu$ tuned in a mass-dependent way, we study the mass spectra of $D$, $D_s$, $\eta_c$, $D^{\ast}$, $D_s^{\ast}$ and $J/\psi$ mesons. The results extrapolated to the continuum limit are compared with the experiment and qualitative agreement is found.Comment: 8 pages, 2 figures, latex fil