2,239 research outputs found

    Possible quantum phase-manipulation of a two-leg ladder in mixed-dimensional fermionic cold atoms

    Full text link
    The recent realization of mixed-dimensional systems of cold atoms has attracted much attention from both experimentalists and theorists. Different effective interactions and novel correlated quantum many-body phases may be engineered in these systems, with the different phases being tunable via external parameters. In this article we investigate a two-species Fermi atom mixture: one species of atom exists in two hyperfine states and is confined to move in a two-leg ladder, interacting with an on-site interaction, and the other moves freely in a two dimensional square lattice that contains the two-leg ladder. The two species of atoms interact via an on-site interaction on the ladder. In the limit of weak inter-species interactions, the two-dimensional gas can be integrated out, leading to an effective long-range mediated interaction in the ladder, generated by to the on-site inter-species interaction. We show that the form of the mediated interaction can be controlled by the density of the two-dimensional gas and that it enhances the charge density wave instability in the two-leg ladder after the renormalization group transformation. Parameterizing the phase diagram with various experimentally controllable quantities, we discuss the possible tuning of the macroscopic quantum many-body phases of the two-leg ladder in this mixed-dimensional fermionic cold atom system.Comment: 4 pages and 3 figure

    Unconventional superconducting phases on a two-dimensional extended Hubbard model

    Get PDF
    We study the phase diagram of the extended Hubbard model on a two-dimensional square lattice, including on-site (U) and nearest-neighbor (V) interactions, at weak couplings. We show that the charge-density-wave phase that is known to occur at half-filling when 4V > U gives way to a d_{xy} -wave superconducting instability away from half-filling, when the Fermi surface is not perfectly nested, and for sufficiently large repulsive and a range of on-site repulsive interaction. In addition, when nesting is further suppressed and in presence of a nearest-neighbor attraction, a triplet time-reversal breaking (p_x + ip_y)-wave pairing instability emerges, competing with the d_{x2+y2} pairing state that is known to dominate at fillings just slightly away from half. At even smaller fillings, where the Fermi surface no longer presents any nesting, the (p_x +ip_y)-wave superconducting phase dominates in the whole regime of on-site repulsions and nearest-neighbor attractions, while d_{xy}-pairing occurs in the presence of on-site attraction. Our results suggest that zero-energy Majorana fermions can be realized on a square lattice in the presence of a magnetic field. For a system of cold fermionic atoms on a two-dimensional square optical lattice, both an on-site repulsion and a nearest-neighbor attraction would be required, in addition to rotation of the system to create vortices. We discuss possible ways of experimentally engineering the required interaction terms in a cold atom system

    Diversification as a Value-Adding Strategy for Asian REITs: A Myth or Reality?

    Get PDF
    This study tests the impact of diversification strategies on the cash flows, expenses, risks and returns of REITs in Asia. Hirschman-Herfindahl indices (HHI) are computed based on 2281 properties owned by 63 sample Asian REITs for the periods from 2002 to 2007 to measure the levels of diversification by property type and geographical region. In our empirical tests that use weighted least square regressions, we find no significant effects of diversification by property types on cash flows, expenses and risk premiums of Asian REITs. However, significant variations in expenses and risk premiums of the REITs are explained by a geographical diversification strategy. REITs with assets distributed across different countries incur higher total expenses, interest expenses, general and administrative expenses and capital expenditure. Regionally diversified REITs have higher risk premiums. The results remain unchanged after controlling for country factor and simultaneity between the cash flows, expenses, risk and return variables.Diversification and focus strategies; Asian REITs; Illiquidity premiums

    d_{xy}-Density wave in fermion-fermion cold atom mixtures

    Full text link
    We study density wave instabilities in a doubly-degenerate Fermi-Fermi mixture with SU(2)×SU(2)SU(2)\times SU(2) symmetry on a square lattice. For sufficiently large on-site inter-species repulsion, when the two species of fermions are both at half-filling, two conventional (ss-wave) number density waves are formed with a π\pi-phase difference between them to minimize the inter-species repulsion. Upon moving one species away from half-filling, an unconventional density wave with dxyd_{xy}-wave symmetry emerges. When both species are away from the vicinity of half-filling, superconducting instabilities dominate. We present results of a functional renormalization-group calculation that maps out the phase diagram at weak couplings. Also, we provide a simple explanation for the emergence of the dxyd_{xy}-density wave phase based on a four-patch model. We find a robust and general mechanism for dxyd_{xy}-density-wave formation that is related to the shape and size of the Fermi surfaces. The density imbalance between the two species of fermions in the vicinity of half-filling leads to phase-space discrepancy for different inter-species Umklapp couplings. Using a phase space argument for leading corrections in the one-loop renormalization group approach to fermions, we show that the phase-space discrepancy in our system causes opposite flows for the two leading intra-species Umklapp couplings and that this triggers the dxyd_{xy}-density-wave instability.Comment: revised long version; 8 pages, 7 figure

    Prognostic factors associated with the survival of oral and pharyngeal carcinoma in Taiwan

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>In Taiwan, a distinct ethnic group variation in incidence and mortality rates has been suggested for most carcinomas. Our aim is to identify the role of prognostic factors associated with the survival of oral and pharyngeal carcinoma in Taiwan.</p> <p>Methods</p> <p>Taiwan Cancer Registry records of 9039 subjects diagnosed with oral and pharyngeal carcinoma were analyzed. The population was divided into three ethnic groups by residence, which were Taiwanese aborigines, Hakka and Hokkien communities. Five-year survival rates were estimated by Kaplan-Meier methods. Ethnic curves differed significantly by log-rank test; therefore separate models for Taiwanese aborigines, Hakka and Hokkien were carried out. The Cox multivariate proportional hazards model was used to examine the role of prognostic factors on ethnic survival.</p> <p>Results</p> <p>The five-year survival rates of oral and pharyngeal carcinoma were significantly poorer for Hokkien community (53.9%) and Taiwanese aborigines community (58.1%) compared with Hakka community (60.5%). The adjusted hazard ratio of Taiwanese aborigines versus Hakka was 1.07 (95%CI, 0.86–1.33) for oral and pharyngeal carcinoma mortality, and 1.16 (95%CI, 1.01–1.33) for Hokkien versus Hakka. Males had significantly poor prognosis than females. Subjects with tongue and/or mouth carcinoma presented the worst prognosis, whereas lip carcinoma had the best prognosis. Subjects with verrucous carcinoma had better survival than squamous cell carcinoma. Prognosis was the worst in elderly subjects, and subjects who underwent surgery had the highest survival rate.</p> <p>Conclusion</p> <p>Our study presented that predictive variables in oral and pharyngeal carcinoma survival have been: ethnic groups, period of diagnosis, gender, diagnostic age, anatomic site, morphologic type, and therapy.</p

    Mechanism of Evolution Shared by Gene and Language

    Full text link
    We propose a general mechanism for evolution to explain the diversity of gene and language. To quantify their common features and reveal the hidden structures, several statistical properties and patterns are examined based on a new method called the rank-rank analysis. We find that the classical correspondence, "domain plays the role of word in gene language", is not rigorous, and propose to replace domain by protein. In addition, we devise a new evolution unit, syllgram, to include the characteristics of spoken and written language. Based on the correspondence between (protein, domain) and (word, syllgram), we discover that both gene and language shared a common scaling structure and scale-free network. Like the Rosetta stone, this work may help decipher the secret behind non-coding DNA and unknown languages.Comment: 15 pages, 13 figures, 3 tabl

    Associations between blood glucose level and outcomes of adult in-hospital cardiac arrest: a retrospective cohort study

    Get PDF
    Additional file 3: Table S3. Features, interventions, and outcomes of cardiac arrest events stratified by the presence of measurement of blood glucose level after sustained return of spontaneous circulation

    Safety, tolerability, and pharmacokinetics of TG-1000, a new molecular entity against influenza virus: first-in-human study

    Get PDF
    Background: The cap-snatching mechanism of influenza virus mRNA transcription is strongly suppressed by TG-1000, a prodrug rapidly metabolized into TG-0527, is a potent cap-dependent nucleic acid endonuclease inhibitor. Herein, we aimed to assess the safety, tolerability, and pharmacokinetics of TG-1000 in healthy participants and the effect of food on the pharmacokinetics and safety of TG-1000.Method: The study was divided into 2 parts: Part A [Single Ascending-Dose (SAD) study, 10–160 mg] and Part B [Food-Effect (FE) study, 40 mg] were launched sequentially. The study included 66 participants for both investigations. We administered different TG-1000 capsules or placebo doses per the study protocol and collected blood samples for pharmacokinetic assessments at specific times. In plasma, TG-1000 and its active metabolite TG-0527 were assayed, and PK parameters were determined.Results: In SAD, the increase in AUC was less than the proportional increase in dose over the 20–160 mg dose range, while the increase in Cmax was proportional to the increase in dose. In the 10–160 mg dose range, T1/2, λz and Tmax of TG-0527 were dose-independent; and T1/2 and Tmax were within 33.8–39.4 h and 3.02–6 h, respectively. In FE, the AUC0-inf, AUC0-last, and Cmax of TG-0527 decreased by approximately 17.52%, 18.76%, and 41.35%, respectively, and the Tmax delay was around 1.50 h. No serious adverse events occurred during the studies.Conclusion: Overall, TG-1000 was well tolerated and exhibited an acceptable safety and PK profile, supporting further clinical investigation of TG-1000 for the treatment of influenza
    corecore