Dynamical Mean Field Theory for the Bose-Hubbard Model

The dynamical mean field theory (DMFT), which is successful in the study of strongly correlated fermions, was recently extended to boson systems [Phys. Rev. B {\textbf 77}, 235106 (2008)]. In this paper, we employ the bosonic DMFT to study the Bose-Hubbard model which describes on-site interacting bosons in a lattice. Using exact diagonalization as the impurity solver, we get the DMFT solutions for the Green's function, the occupation density, as well as the condensate fraction on a Bethe lattice. Various phases are identified: the Mott insulator, the Bose-Einstein condensed (BEC) phase, and the normal phase. At finite temperatures, we obtain the crossover between the Mott-like regime and the normal phase, as well as the BEC-to-normal phase transition. Phase diagrams on the $\mu/U-\tilde{t}/U$ plane and on the $T/U-\tilde{t}/U$ plane are produced ($\tilde{t}$ is the scaled hopping amplitude). We compare our results with the previous ones, and discuss the implication of these results to experiments.Comment: 11 pages, 8 figure

The Revolving Door: A Report on U.S. Hospital Readmissions

The U.S. health care system suffers from a chronic malady -- the revolving door syndrome at its hospitals. It is so bad that the federal government says one in five elderly patients is back in the hospital within 30 days of leaving.Some return trips are predictable elements of a treatment plan. Others are unplanned but difficult to prevent: patients go home, new and unexpected problems arise, and they require an immediate trip back to the hospital.But many of these readmissions can and should be prevented. They are the result of a fragmented system of care that too often leaves discharged patients to their own devices, unable to follow instructions they didn't understand, and not taking medications or getting the necessary follow-up care.The federal government has pegged the cost of readmissions for Medicare patients alone at $26 billion annually, and says more than$17 billion of it pays for return trips that need not happen if patients get the right care. This is one reason the Centers for Medicare & Medicaid Services has identified avoidable readmissions as one of the leading problems facing the U.S. health care system and now penalizes hospitals with high rates of readmissions for their heart failure, heart attack, and pneumonia patients. This report is being released in conjunction with the Robert Wood John Foundation's Care About Your Care initiative, which is devoted to improving care transitions when people leave the hospital. It looks at the issue of readmissions in two ways: by the numbers and through the eyes of the people who live them

Optoelectronics of Inverted Type-I CdS/CdSe Core/Crown Quantum Ring

Inverted type-I heterostructure core/crown quantum rings (QRs) are quantum-efficient luminophores, whose spectral characteristics are highly tunable. Here, we study the optoelectronic properties of type-I core/crown CdS/CdSe QRs in the zincblende phase - over contrasting lateral size and crown width. For this we inspect their strain profiles, transition energies, transition matrix elements, spatial charge densities, electronic bandstructure, band-mixing probabilities, optical gain spectra, maximum optical gains and differential optical gains. Our framework uses an effective-mass envelope function theory based on the 8-band k$\cdot$p method employing the valence force field model for calculating the atomic strain distributions. The gain calculations are based on the density-matrix equation and take into consideration the excitonic effects with intraband scattering. Variations in the QR lateral size and relative widths of core and crown (ergo the composition) affect their energy levels, band-mixing probabilities, optical transition matrix elements, emission wavelengths/intensity, etc. The optical gain of QRs is also strongly dimension and composition dependent with further dependency on the injection carrier density causing band-filling effect. They also affect the maximum and differential gain at varying dimensions and compositions.Comment: Published in AIP Journal of Applied Physics (11 pages, 7 figures

QCD Effects in High Energy Processes

In this talk, some important QCD effects in Higgs physics, supersymmetry and top physics, as well as the factorization and resummation techniques in QCD are reviewed.Comment: LaTeX, 13 pages, uses ws-ijmpa.cls. Based on an invited talk at the International Conference on QCD and Hadronic Physics, Beijing, China, June 16--20, 2005. Minor change

The Strong Decay Patterns of the 1−+1^{-+} Exotic Hybrid Mesons

We calculate the coupling constants of the decay modes $1^{-+}\rightarrow\rho\pi, f_1\pi, b_1\pi, \eta\pi, \eta'\pi, a_1\pi, f_1\eta$ within the framework of the light-cone QCD sum rule. Then we calculate the partial width of these decay channels, which differ greatly from the existing calculations using phenomenological models. For the isovector $1^{-+}$ state, the dominant decay modes are $\rho\pi, f_1\pi$. For its isoscalar partner, its dominant decay mode is $a_1\pi$. We also discuss the possible search of the $1^{-+}$ state at BESIII, for example through the decay chains $J/\psi (\psi')\to \pi_1 +\gamma$ or $J/\psi (\psi')\to \pi_1 +\rho$ where $\pi_1$ can be reconstructed through the decay modes $\pi_1\to \rho\pi\to \pi^+\pi^-\pi^0$ or $\pi_1\to f_1(1285)\pi^0$. Hopefully the present work will be helpful to the experimental establishment of the $1^{-+}$ hybrid meson.Comment: 14 pages, 10 figure

A CrC^{r} Closing Lemma for a Class of Symplectic Diffeomorphisms

We prove a $C^r$ closing lemma for a class of partially hyperbolic symplectic diffeomorphisms. We show that for a generic $C^r$ symplectic diffeomorphism, $r =1, 2, ...,$, with two dimensional center and close to a product map, the set of all periodic points is dense

Trends and Variation in End-of-Life Care for Medicare Beneficiaries With Severe Chronic Illness

Provides an updated analysis of regional and hospital variations in end-of-life care for Medicare beneficiaries with chronic illnesses, including percentage of hospital deaths, days in intensive care units, and physician labor per patient