4,790 research outputs found

    Topologically distinct critical theories emerging from the bulk entanglement spectrum of integer quantum Hall states on a lattice

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    The critical theories for the topological phase transitions of integer quantum Hall states to a trivial insulating state with the same symmetry can be obtained by calculating the ground state entanglement spectrum under a symmetric checkerboard bipartition. In contrast to the gapless edge excitations under the left-right bipartition, a quantum network with bulk gapless excitations naturally emerges at the Brillouin zone center without fine tuning. On a large finite lattice, the resulting critical theory for the ν=1\nu =1 state is the (2+1) dimensional relativistic quantum field theory characterized by a \textit{single} Dirac cone spectrum and a pair of \textit{fractionalized} zero-energy states, while for the ν=2\nu =2 state the critical theory exhibits a parabolic spectrum and no sign of fractionalization in the zero-energy states. A triangular correspondence is established among the bulk topological theory, gapless edge theory, and the critical theory via the ground state entanglement spectrum.Comment: 5 pages, 4 figures, published versio

    Identifying Product Order with Restricted Boltzmann Machines

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    Unsupervised machine learning via a restricted Boltzmann machine is an useful tool in distinguishing an ordered phase from a disordered phase. Here we study its application on the two-dimensional Ashkin-Teller model, which features a partially ordered product phase. We train the neural network with spin configuration data generated by Monte Carlo simulations and show that distinct features of the product phase can be learned from non-ergodic samples resulting from symmetry breaking. Careful analysis of the weight matrices inspires us to define a nontrivial machine-learning motivated quantity of the product form, which resembles the conventional product order parameter.Comment: 9 pages, 11 figure

    Emerging criticality in the disordered three-color Ashkin-Teller model

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    We study the effects of quenched disorder on the first-order phase transition in the two-dimensional three-color Ashkin-Teller model by means of large-scale Monte Carlo simulations. We demonstrate that the first-order phase transition is rounded by the disorder and turns into a continuous one. Using a careful finite-size-scaling analysis, we provide strong evidence for the emerging critical behavior of the disordered Ashkin-Teller model to be in the clean two-dimensional Ising universality class, accompanied by universal logarithmic corrections. This agrees with perturbative renormalization-group predictions by Cardy. As a byproduct, we also provide support for the strong-universality scenario for the critical behavior of the two-dimensional disordered Ising model. We discuss consequences of our results for the classification of disordered phase transitions as well as generalizations to other systems.Comment: 18 pages, 18 eps figures included, final version as publishe

    Hepatic bile acids and bile acid-related gene expression in pregnant and lactating rats

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    Background. Significant physiological changes occur during pregnancy and lactation. Intrahepatic cholestasis of pregnancy (ICP) is a liver disease closely related to disruption of bile acid homeostasis. The objective of this study was to examine the regulation of bile acid synthesis and transport in normal pregnant and lactating rats.Materials and Methods. Livers from timed pregnant SD rats were collected on gestational days (GD) 10, 14 and 19, and postnatal days (PND) 1, 7, 14 and 21. Total bile acids were determined by the enzymatic method, total RNA was isolated and subjected to real time RT-PCR analysis. Liver protein was extracted for western-blot analysis.Results. Under physiological conditions hepatic bile acids were not elevated during pregnancy but increased during lactation in rats. Bile acid synthesis rate-limiting enzyme Cyp7a1 was unchanged on gestational days, but increased on PND14 and 21 at mRNA and protein levels. Expression of Cyp8b1, Cyp27a1 and Cyp7b1 was also higher during lactation. The mRNA levels of small heterodimer partner (SHP) and protein levels of farnesoid X receptor (FXR) were increased during pregnancy and lactation. Bile acid transporters Ntcp, Bsep, Mrp3 and Mrp4 were lower at gestation, but increased during lactation. Hepatic Oatp transporters were decreased during pregnancy and lactation.Conclusion. Hepatic bile acid homeostasis is maintained during normal pregnancy in rats, probably through the FXR-SHP regulation. The expression of bile acid synthesis genes and liver bile acid accumulation were increased during lactation, together with increased expression of bile acid efflux transporter Bsep, Mrp3 and Mrp4

    Geometric phases for wave packets in a uniform magnetic field

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    A wave packet of a charged particle always make cyclic circular motion in a uniform magnetic field, just like a classical particle. The nonadiabatic geometric phase for an arbitrary wave packet can be expressed in terms of the mean value of a number operator. For a large class of wave packets, the geometric phase is proportional to the magnetic flux encircled by the orbit of the wave packet. For more general wave packets, however, the geometric phase contains an extra term.Comment: REVTeX4, 7 pages, no figur

    The correlation between the expression of differentiated embryo-chondrocyte expressed gene l and oral squamous cell carcinoma

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    BACKGROUND: This study aims to explore the correlation between expression of differentiated embryo-chondrocyte expressed gene l (DEC1) and oral squamous cell carcinoma (OSCC), which could provide the reference for treatment and prognosis assessment of OSCC. METHODS: The expression of DEC1 in tissues from 56 primary OSCC patients and 20 normal oral mucosa samples were detected using real-time polymerase chain reaction and immunohistochemical methods, respectively. RESULTS: The results showed that the positive expression rate of DEC1 in the OSCC group was significantly higher than that in the normal group (P <0.05); further, the expression of DEC1 in different OSCC groups was statistically significant (P <0.05). The expression of DEC1 in the 1-year recurrence OSCC group was significantly higher than other groups. The expression of DEC1 in the 3-years no recurrence OSCC group was the lowest. CONCLUSIONS: The expression of DEC1 was associated with the incidence of OSCC and there was a negative correlation between the expression of DEC1 and the prognosis of OSCC

    Public Higher Education Governing Boards Composition and Regional Difference in U.S

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    [EN] Using The Public Higher Education Boards Database designed by Association of Governing Boards of Universities and Colleges (AGB) in 2008, this paper reviewed prior studies of governing boards and investigated regional differences of boards' characteristics including board type, selection method, board composition, provision condition, term length, supervision, and meeting frequency. The results show tha: (1) highly centralized state university governance with more political control exist in West and Middle West; (2) governing boards in Northeast are more autonomous with high percentage of alumni and self-perpetuating members and less political affiliations; (3) more faculty participations appear in South and West, and most Middle West boards do not have removal process and longer length of term.Park, HJ.; Zhu, Q. (2017). Public Higher Education Governing Boards Composition and Regional Difference in U.S. En Proceedings of the 3rd International Conference on Higher Education Advances. Editorial Universitat Politècnica de València. 1085-1094. https://doi.org/10.4995/HEAD17.2017.5519OCS1085109
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