18,988 research outputs found

    Accounting for the Effect of Internal Viscosity in Dumbbell Models for Polymeric Fluids and Relaxation of DNA

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    The coarse-graining approach is one of the most important mod- eling methods in research of long-chain polymers such as DNA molecules. The dumbbell model is a simple but e±cient way to describe the behavior of polymers in solutions. In this paper, the dumbbell model with internal viscosity (IV) for concentrated polymeric liquids is analyzed for the steady-state and time-dependent elongational flow and steady-state shear °ow. In the elongational flow case, by analyzing the governing ordinary di®erential equations the contribution of the IV to the stress tensor is discussed for fluids subjected to a sudden elongational jerk. In the shear °ow case, the governing stochastic differential equation of the finitely extensible nonlinear elastic dumbbell model is solved numerically. For this case, the extensions of DNA molecules for different shear rates are analyzed, and the comparison with the experimental data is carried out to estimate the contribution of the e®ect of internal viscosity

    Phenomenological discriminations of the Yukawa interactions in two-Higgs doublet models with Z2Z_2 symmetry

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    There are four types of two-Higgs doublet models under a discrete Z2Z_2 symmetry imposed to avoid tree-level flavour-changing neutral current, i.e. type-I, type-II, type-X and type-Y models. We investigate the possibility to discriminate the four models in the light of the flavour physics data, including BsBˉsB_s-\bar B_s mixing, Bs,dμ+μB_{s,d} \to \mu^+ \mu^-, BτνB\to \tau\nu and BˉXsγ\bar B \to X_s \gamma decays, the recent LHC Higgs data, the direct search for charged Higgs at LEP, and the constraints from perturbative unitarity and vacuum stability. After deriving the combined constraints on the Yukawa interaction parameters, we have shown that the correlation between the mass eigenstate rate asymmetry AΔΓA_{\Delta\Gamma} of Bsμ+μB_{s} \to \mu^+ \mu^- and the ratio R=B(Bsμ+μ)exp/B(Bsμ+μ)SMR={\cal B}(B_{s} \to \mu^+ \mu^-)_{exp}/ {\cal B}(B_{s} \to \mu^+ \mu^-)_{SM} could be sensitive probe to discriminate the four models with future precise measurements of the observables in the Bsμ+μB_{s} \to \mu^+ \mu^- decay at LHCb.Comment: 29 pages, 4 tables, 11 figures. v3: minor corrections included, matches published version in EPJ

    The unique mouse pollination in an orchid species

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    The Chinese orchid, _Cymbidium serratum_, is pollinated by the wild mountain mouse _Rattus fulvescens_. The flowers use both odor and colour as attractants, and provide labellum as food reward for the pollinators. The mice pollinate the flowers during their endeavour to eat the labellums

    Why Do Women Have Longer Unemployment Durations than Men in Post-Restructuring Urban China?

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    This paper provides the first systematic analysis of the reasons why women endure longer unemployment durations than men in post-restructuring urban China using data obtained from a national representative household survey. Rejecting the view that women are less earnest than men in their desire for employment, the analysis shows that women's job search efforts are handicapped by lack of access to social networks, social stereotyping (that married women are unreliable employees), unequal access to social reemployment services stemming from sex segregation prior to the displacement, and wage discrimination in the post-restructuring labor market.Gender inequality, unemployment duration, Oaxaca-decomposition

    Role of Spironolactone Chalcone in the Prevention of Peritoneal Fibrosis in Patients with Peritoneal Dialysis

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    Purpose: The study was designed to investigate the effects of a novel spironolactone chalcone in the prevention of peritoneal fibrosis.Methods: Wistar rats (n = 30) were randomly assigned to 3 groups: bacteria (B), spironolactone amide treatment (S), and control (C) groups. C group received only dextran beads while S and B groups were given bacteria and dextran beads intraperitoneally, but spironolactone chalcone was also given to S group. The treatments were administered daily. The rats were sacrificed on day 15 to quantify peritoneal adhesion and for histological examination of the peritoneal tissues using hematoxylin, eosin and Masson’s trichrome dyes. Enzyme-linked immunosorbent assay (ELISA) kit was used to determine TGFβ1 content of peritoneal fluids and serum samples.Results: Spironolactone chalcone treatment at a dose of 30 mg/kg body weight daily for 15 days significantly reduced peritoneal total adhesion score in S group compared to untreated B group (p < 0.01). S group also showed significantly lower mean peritoneal thickness, inflammation score, and fibrosis score compared to B group. Serum transforming growth factor β1 was also reduced significantly in S group animals on spironolactone chalcone treatment compared to B group.Conclusion: Spironolactone chalcone is a potentially effective candidate for decreasing the extent of peritoneal injury caused by bacterial peritonitis.Keywords: Peritoneal thickness, Inflammation score, Adhesion score, Bacterial peritonitis, Peritoneal fluid

    H∞ optimal control of vehicle active suspension systems in two time scales

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    In this paper, a novel H∞ control method in two time scales is proposed for active suspension systems. Two time scales are considered based on the natural time scale separation existing in the active suspension systems, i.e. the sprung mass part corresponding to the fast dynamics and the unsprung mass part corresponding to the slow dynamics. Singular perturbation theory is used to establish a dual time scale active suspension model and design a H∞ controller. Compared with the commonly used H∞ controller, the time-sharing dynamic characteristics make the proposed two time scales H∞ controller have better dynamic response when encountering dynamic road input, so as to better meet the control performance requirements of active suspension. The effectiveness of the proposed H∞ control method in two time scales is illustrated through co-simulations
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