Interaction-induced Metal to Topological Insulator Transition

By means of exact diagonalizations, the Bernevig-Hughes-Zhang model at quarter-filling in the limit of strong Hubbard on-site repulsion is investigated. We find that the non-interacting metallic state will be turned into a Chern insulator with saturated magnetization under strong correlations. That is, at such a metal-insulator transition, both the topological and the magnetic properties of the system are changed due to spontaneous breaking of time reversal symmetry in the ground states. According to our findings, this topological phase transition seems to be of first order. Our results illustrate the interesting physics in topological Mott transitions and provide guidance to the search of more interaction-induced topological phases in similar systems.Comment: 6 pages, 4 figure

Multiple Objective Planning for Production and Distribution Model of Supply Chain: Case of Bicycle Manufacturer

Under increasing globalization, enterprises view supply chains (SC) as an integration of process control and management. The bicycle industry is one of the competitive industries in Taiwan, for which there is a complete supply chain system. To internationalize and improve the competitive advantage of this industry, it is necessary for it to improve the capacity of global production and distribution. In this paper, we consider both the maximum profit of enterprises and the maximum quality of customer service, using five programming methods to construct multi-objective production and distribution models. These five methods are: compromise programming, fuzzy multi-objective programming, weighted multi-objective programming, weighted fuzzy multi-objective programming and two-phase fuzzy multi-objective programming. The results reveal that the weighted multi-objective model was better for considering the maximum profit of enterprises and the maximum quality of customer service. Finally, we use the weighted multi-objective model for sensitivity analysis. These results show that after raising the per-unit production cost in production processes, the total profit would decrease. In addition, if the unit inventory cost increases due to improving the customer service level, then the total profit might increase, but not significantly. Furthermore, the shortage cost seems have interactive behavior on the enterprises, in which an increase of inventory cost will lower shortage cost

General properties of fidelity in non-Hermitian quantum systems with PT symmetry

The fidelity susceptibility is a tool for studying quantum phase transitions in the Hermitian condensed matter systems. Recently, it has been generalized with the biorthogonal basis for the non-Hermitian quantum systems. From the general perturbation description with the constrain of parity-time (PT) symmetry, we show that the fidelity $\mathcal{F}$ is always real for the PT-symmetric states. For the PT-broken states, the real part of the fidelity susceptibility equals to one half of the sum of the fidelity susceptibility of the PT-broken and the PT-partner states, $\mathrm{Re}[\mathcal{X}_F] = \frac{1}{2}(\mathcal{X}_F +\bar{\mathcal{X}}_F)$. The negative infinity of the fidelity susceptibility is explored by the perturbation theory when the parameter approaches the exceptional point (EP). Moreover, at the second-order EP where two eigenstates and eigenenergies coalesce, we prove that the real part of the fidelity between PT-symmetric and PT-broken states is $\mathrm{Re}\mathcal{F}=\frac{1}{2}$. We demonstrate these general properties for non-interacting and interacting systems by two examples: the two-legged non-Hermitian Su-Schrieffer-Heeger (SSH) model and the non-Hermitian XXZ spin chain.Comment: 14 pages, 8 figure

Patrones individuales de dispersión de larvas de góbidos en un estudiaro indicados por la composición elemental de los otolitos

Otolith trace elements were used as natural tags to study the dispersal patterns of goby larvae in an estuary. Ninety-six larval gobies representing 10 species were collected in the estuary of Gongshytyan Creek in northwestern Taiwan in September 1997. Fifteen trace elements in fish otoliths were analysed with solution-based ICPMS. Trace elemental composition in otoliths differed significantly among the species. Habitat use by the larvae of the 10 species can be divided into four groups, based on principal component analysis of otolith elemental composition. All 10 goby species used the estuary as a nursery area irrespective of the fish being amphidromous or non-amphidromous. A part of the population may be lost during larval dispersal, as indicated from trace elemental composition recorded in the otolith.Se utilizó la composición elemental en los otolitos de larvas de góbidos como trazadores naturales para estudiar los patrones de dispersión en un estuario. Durante septiembre de 1997 se recolectaron 96 larvas de góbidos pertenecientes a 10 especies distintas en el estuario de Gongshytyan Creek situado en el noroeste de Taiwan . Se analizaron 15 elementos traza mediante espectroscopia de masas (ICPMS). La composición de elementos traza en los otolitos difirió significativamente entre especies. En base al Análisis de Componentes Principales de la composición elemental de los otolitos, los hábitats utilizados por las 10 especies pudieron dividirse en 4 grupos. Las 10 especies de góbidos usan el estuario como área de cría, independientemente de que las especies sean anfidromas o no-anfidromas. La composición elemental determinada para los otolitos analizados, permitió comprobar que una parte de la población puede ser perdida durante la dispersión larvaria

Cirsium tatakaense (Compositae), a new species from Taiwan

A new species of Cirsium, Cirsium tatakaense Y.H.Tseng & C.Y.Chang, from central-southern Taiwan is described and illustrated. This species is similar to C. kawakamii Hayata in leaf shape, achene and chromosome number (2n = 64), but can be readily distinguished from C. kawakamii by the narrower leaf lobes, usually higher number of florets and phyllaries, the purplish-red corolla (vs. white) and larger pollen grains. A key to the species of Cirsium in Taiwan is also presented

Electroacupuncture-Induced Cholinergic Nerve Activation Enhances the Hypoglycemic Effect of Exogenous Insulin in a Rat Model of Streptozotocin-Induced Diabetes

The aim of this study is to explore the mechanisms by which electroacupuncture (EA) enhances the hypoglycemic effect of exogenous insulin in a streptozotocin- (STZ-) diabetic rats. Animals in the EA group were anesthetized and subjected to the insulin challenge test (ICT) and EA for 60 minutes. In the control group, rats were subjected to the same treatment with the exception of EA stimulation. Blood samples were drawn to measure changes in plasma glucose, free fatty acids (FFA), and insulin levels. Western blot was used to assay proteins involved in insulin signaling. Furthermore, atropine, hemicholinium-3 (HC-3), and Eserine were used to explore the relationship between EA and cholinergic nerve activation during ICT. EA augmented the blood glucose-lowering effects of EA by activating the cholinergic nerves in STZ rats that had been exposed to exogenous insulin. This phenomenon may be related to enhancement of insulin signaling rather than to changes in FFA concentration

Acute effect of electroacupuncture at the Zusanli acupoints on decreasing insulin resistance as shown by lowering plasma free fatty acid levels in steroid-background male rats

<p>Abstract</p> <p>Background</p> <p>Insulin sensitivity has been enhanced by electroacupuncture (EA) in rats, but the EA phenomenon in an insulin resistant state is still unclear. This study reports the use of a large dose of prednisolone to evaluate the effects of EA in a state of insulin resistance.</p> <p>Methods</p> <p>The plasma levels of free fatty acids (FFAs) were estimated in steroid-background rats (SBRs) and compared with those in healthy rats treated with normal saline. In addition, plasma glucose and endogenous insulin levels were assayed to calculate the homeostasis model assessment (HOMA) index. Intravenous glucose tolerance test (IVGTT) was carried out to compare glucose tolerance. The SBRs were randomly divided into EA-treatment and non-EA treatment groups and 15-Hz EA was applied to the bilateral Zusanli acupoints to investigate its effects on insulin resistance. In addition to an insulin challenge test (ICT) and IVGTT, the plasma levels of FFAs were measured and western blot was performed to help determine the effects of EA on the insulin resistant state.</p> <p>Results</p> <p>The plasma levels of FFAs increased markedly in SBRs, the HOMA index was markedly higher, and glucose tolerance was impaired. EA improved glucose tolerance and insulin sensitivity by decreasing the plasma levels of FFAs. Further, the insulin signaling proteins (IRS1) and glucose transporter isoform protein (GLUT4) in skeletal muscle inhibited by prednisolone recovered after EA.</p> <p>Conclusion</p> <p>Insulin resistance was successfully induced by a large dose of prednisolone in male rats. This insulin resistance can be improved by 15 Hz EA at the bilateral Zusanli acupoints, as shown by decreased plasma levels of FFAs.</p

Electroacupuncture at the Zusanli (ST-36) Acupoint Induces a Hypoglycemic Effect by Stimulating the Cholinergic Nerve in a Rat Model of Streptozotocine-Induced Insulin-Dependent Diabetes Mellitus

Animal studies have shown that electroacupuncture (EA) at Zusanli (ST-36) and Zhongwan (CV-12) acupoints reduces plasma glucose concentrations in rats with type II diabetes. However, whether EA reduces plasma glucose levels in type I diabetes is still unknown. In this study, we explore the various non-insulin-dependent pathways involved in EA-induced lowering of plasma glucose. Streptozotocin (STZ) (60 mg kg−1, i.v.) was administered via the femoral vein to induce insulin-dependent diabetes in non-adrenalectomized and in adrenalectomomized rats. EA (15 Hz) was applied for 30 min to bilateral ST-36 acupoints after administration of Atropine (0.1 mg kg−1 i.p.), Eserine (0.01 mg kg−1 i.p.), or Hemicholinium-3 (5 μg kg−1 i.p.) in non-adrenalectomized rats. Rats administered acetylcholine (0.01 mg kg−1 i.v.) did not undergo EA. Adrenalectomized rats underwent EA at bilateral ST-36 acupoints without further treatment. Blood samples were drawn from all rats before and after EA to measure changes in plasma glucose levels. Expression of insulin signaling proteins (IRS1, AKT2) in atropine-exposed rats before and after EA was measured by western blot. Atropine and hemicholinium-3 completely blocked the plasma glucose lowering effects of EA, whereas eserine led to a significant hypoglycemic response. In addition, plasma glucose levels after administration of acetylcholine were significantly lower than the fasting glucose levels. In STZ-adrenalectomized rats, EA did not induce a hypoglycemic response. EA stimulated the expression of IRS1 and AKT2 and atropine treatment blocked the EA-induced expression of those insulin signaling proteins. Taken together, EA at the ST-36 acupoint reduces plasma glucose concentrations by stimulating the cholinergic nerves