969 research outputs found

    Maximum solutions of normalized Ricci flows on 4-manifolds

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    We consider maximum solution g(t)g(t), t[0,+)t\in [0, +\infty), to the normalized Ricci flow. Among other things, we prove that, if (M,ω)(M, \omega) is a smooth compact symplectic 4-manifold such that b2+(M)>1b_2^+(M)>1 and let g(t),t[0,)g(t),t\in[0,\infty), be a solution to (1.3) on MM whose Ricci curvature satisfies that Ric(g(t))3|\text{Ric}(g(t))|\leq 3 and additionally χ(M)=3τ(M)>0\chi(M)=3 \tau (M)>0, then there exists an mNm\in \mathbb{N}, and a sequence of points {xj,kM}\{x_{j,k}\in M\}, j=1,...,mj=1, ..., m, satisfying that, by passing to a subsequence, (M,g(tk+t),x1,k,...,xm,k)dGH(j=1mNj,g,x1,,...,,xm,),(M, g(t_{k}+t), x_{1,k},..., x_{m,k}) \stackrel{d_{GH}}\longrightarrow (\coprod_{j=1}^m N_j, g_{\infty}, x_{1,\infty}, ...,, x_{m,\infty}), t[0,)t\in [0, \infty), in the mm-pointed Gromov-Hausdorff sense for any sequence tkt_{k}\longrightarrow \infty, where (Nj,g)(N_{j}, g_{\infty}), j=1,...,mj=1,..., m, are complete complex hyperbolic orbifolds of complex dimension 2 with at most finitely many isolated orbifold points. Moreover, the convergence is CC^{\infty} in the non-singular part of 1mNj\coprod_1^m N_{j} and Volg0(M)=j=1mVolg(Nj)\text{Vol}_{g_{0}}(M)=\sum_{j=1}^{m}\text{Vol}_{g_{\infty}}(N_{j}), where χ(M)\chi(M) (resp. τ(M)\tau(M)) is the Euler characteristic (resp. signature) of MM.Comment: 23 page

    Synchronous right hepatectomy and cesarean section in a pregnant lady with hepatocellular carcinoma

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    AbstractINTRODUCTIONCancer in pregnancy is rare and hepatocellular carcinoma (HCC) during pregnancy is even rarer. Due to limited experience, management of these patients remains challenging.PRESENTATION OF CASEA 33-year old pregnant lady presented with HCC at 28 weeks of gestation. She underwent synchronous cesarean section and right hepatectomy at 32 weeks of gestation. The post-operative course was uneventful. She was discharged home on day 10 after surgery. Histolopathology confirmed HCC. The surgical resection margins were clear. At a follow-up of 3 months after surgery, the mother was disease free and the infant was well.DISCUSSIONHCC during pregnancy is extremely rare. The experience in its management and outcomes are lacking. In managing any patient diagnosed with a malignant neoplasm in pregnancy, both the mother and the fetus have to be considered.CONCLUSIONWith adequate preoperative assessment and a good management strategy, good results can be obtained for both the mother and the baby for a pregnant patient with HCC

    The Coupled Cluster Method in Hamiltonian Lattice Field Theory: SU(2) Glueballs

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    The glueball spectrum within the Hamiltonian formulation of lattice gauge theory (without fermions) is calculated for the gauge group SU(2) and for two spatial dimensions. The Hilbert space of gauge-invariant functions of the gauge field is generated by its parallel-transporters on closed paths along the links of the spatial lattice. The coupled cluster method is used to determine the spectrum of the Kogut-Susskind Hamiltonian in a truncated basis. The quality of the description is studied by computing results from various truncations, lattice regularisations and with an improved Hamiltonian. We find consistency for the mass ratio predictions within a scaling region where we obtain good agreement with standard lattice Monte Carlo results.Comment: 13 pages, 7 figure

    Cyclin D1 acts as a barrier to pluripotent reprogramming by promoting neural progenitor fate commitment

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    AbstractA short G1 phase is a characteristic feature of the cell cycle structure of pluripotent cells, and is reestablished during Yamanaka factor-mediated pluripotent reprogramming. How cell cycle control is adjusted to meet the requirements of pluripotent cell fate commitment during reprogramming is less well understood. Elevated levels of cyclin D1 were initially found to impair pluripotency maintenance. The current work further identified Cyclin D1 to be capable of transcriptionally upregulating Pax6, which promoted reprogramming cells to commit to a neural progenitor fate rather than a pluripotent cell fate. These findings explain the importance of reestablishment of G1-phase restriction in pluripotent reprogramming

    Quantum algebra in the mixed light pseudoscalar meson states

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    In this paper, we investigate the entanglement degrees of pseudoscalar meson states via quantum algebra Y(su(3)). By making use of transition effect of generators J of Y(su(3)), we construct various transition operators in terms of J of Y(su(3)), and act them on eta-pion-eta mixing meson state. The entanglement degrees of both the initial state and final state are calculated with the help of entropy theory. The diagrams of entanglement degrees are presented. Our result shows that a state with desired entanglement degree can be achieved by acting proper chosen transition operator on an initial state. This sheds new light on the connect among quantum information, particle physics and Yangian algebra.Comment: 9 pages, 3 figure

    Interface and electronic characterization of thin epitaxial Co3O4 films

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    The interface and electronic structure of thin (~20-74 nm) Co3O4(110) epitaxial films grown by oxygen-assisted molecular beam epitaxy on MgAl2O4(110) single crystal substrates have been investigated by means of real and reciprocal space techniques. As-grown film surfaces are found to be relatively disordered and exhibit an oblique low energy electron diffraction (LEED) pattern associated with the O-rich CoO2 bulk termination of the (110) surface. Interface and bulk film structure are found to improve significantly with post-growth annealing at 820 K in air and display sharp rectangular LEED patterns, suggesting a surface stoichiometry of the alternative Co2O2 bulk termination of the (110) surface. Non-contact atomic force microscopy demonstrates the presence of wide terraces separated by atomic steps in the annealed films that are not present in the as-grown structures; the step height of ~ 2.7 A corresponds to two atomic layers and confirms a single termination for the annealed films, consistent with the LEED results. A model of the (1 * 1) surfaces that allows for compensation of the polar surfaces is presented.Comment: 8 pages, 7 figure

    Charmless BsPP,PV,VVB_s\to PP, PV, VV Decays Based on the six-quark Effective Hamiltonian with Strong Phase Effects II

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    We provide a systematic study of charmless BsPP,PV,VVB_s \to PP, PV, VV decays (PP and VV denote pseudoscalar and vector mesons, respectively) based on an approximate six-quark operator effective Hamiltonian from QCD. The calculation of the relevant hard-scattering kernels is carried out, the resulting transition form factors are consistent with the results of QCD sum rule calculations. By taking into account important classes of power corrections involving "chirally-enhanced" terms and the vertex corrections as well as weak annihilation contributions with non-trivial strong phase, we present predictions for the branching ratios and CP asymmetries of BsB_s decays into PP, PV and VV final states, and also for the corresponding polarization observables in VV final states. It is found that the weak annihilation contributions with non-trivial strong phase have remarkable effects on the observables in the color-suppressed and penguin-dominated decay modes. In addition, we discuss the SU(3) flavor symmetry and show that the symmetry relations are generally respected

    Measurements of J/psi Decays into 2(pi+pi-)eta and 3(pi+pi-)eta

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    Based on a sample of 5.8X 10^7 J/psi events taken with the BESII detector, the branching fractions of J/psi--> 2(pi+pi-)eta and J/psi-->3(pi+pi-)eta are measured for the first time to be (2.26+-0.08+-0.27)X10^{-3} and (7.24+-0.96+-1.11)X10^{-4}, respectively.Comment: 11 pages, 6 figure

    Measurements of the Mass and Full-Width of the ηc\eta_c Meson

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    In a sample of 58 million J/ψJ/\psi events collected with the BES II detector, the process J/ψγηc\psi\to\gamma\eta_c is observed in five different decay channels: γK+Kπ+π\gamma K^+K^-\pi^+\pi^-, γπ+ππ+π\gamma\pi^+\pi^-\pi^+\pi^-, γK±KS0π\gamma K^\pm K^0_S \pi^\mp (with KS0π+πK^0_S\to\pi^+\pi^-), γϕϕ\gamma \phi\phi (with ϕK+K\phi\to K^+K^-) and γppˉ\gamma p\bar{p}. From a combined fit of all five channels, we determine the mass and full-width of ηc\eta_c to be mηc=2977.5±1.0(stat.)±1.2(syst.)m_{\eta_c}=2977.5\pm1.0 ({stat.})\pm1.2 ({syst.}) MeV/c2c^2 and Γηc=17.0±3.7(stat.)±7.4(syst.)\Gamma_{\eta_c} = 17.0\pm3.7 ({stat.})\pm7.4 ({syst.}) MeV/c2c^2.Comment: 9 pages, 2 figures and 4 table. Submitted to Phys. Lett.
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