Electric Dipolar Susceptibility of the Anderson-Holstein Model

The temperature dependence of electric dipolar susceptibility \chi_P is discussed on the basis of the Anderson-Holstein model with the use of a numerical renormalization group (NRG) technique. Note that P is related with phonon Green's function D. In order to obtain correct temperature dependence of P at low temperatures, we propose a method to evaluate P through the Dyson equation from charge susceptibility \chi_c calculated by the NRG, in contrast to the direct NRG calculation of D. We find that the irreducible charge susceptibility estimated from \chi_c agree with the perturbation calculation, suggesting that our method works well.Comment: 4 pages, 4 figure

Electron Mass Enhancement due to Anharmonic Local Phonons

In order to understand how electron effective mass is enhanced by anharmonic local oscillation of an atom in a cage composed of other atoms, i.e., {\it rattling}, we analyze anharmonic Holstein model by using a Green's function method. Due to the evaluation of an electron mass enhancement factor $Z$, we find that $Z$ becomes maximum when zero-point energy is comparable with potential height at which the amplitude of oscillation is rapidly enlarged. Cooperation of such quantum and rattling effects is considered to be a key issue to explain the electron mass enhancement in electron-rattling systems.Comment: 3 pages, 3 figures, to appear in J. Phys. Soc. Jpn. Suppl. (Proceedings for International Conference on Heavy Electrons

Tre1 GPCR initiates germ cell transepithelial migration by regulating Drosophila melanogaster E-cadherin

Despite significant progress in identifying the guidance pathways that control cell migration, how a cell starts to move within an intact organism, acquires motility, and loses contact with its neighbors is poorly understood. We show that activation of the G protein–coupled receptor (GPCR) trapped in endoderm 1 (Tre1) directs the redistribution of the G protein Gβ as well as adherens junction proteins and Rho guanosine triphosphatase from the cell periphery to the lagging tail of germ cells at the onset of Drosophila melanogaster germ cell migration. Subsequently, Tre1 activity triggers germ cell dispersal and orients them toward the midgut for directed transepithelial migration. A transition toward invasive migration is also a prerequisite for metastasis formation, which often correlates with down-regulation of adhesion proteins. We show that uniform down-regulation of E-cadherin causes germ cell dispersal but is not sufficient for transepithelial migration in the absence of Tre1. Our findings therefore suggest a new mechanism for GPCR function that links cell polarity, modulation of cell adhesion, and invasion

The Anti-Competitive Potential of Cross-Market Mergers in Health Care

Health care consolidation in the United States has been widespread at all levels and across all entities. This consolidation has extended beyond horizontal mergers of hospitals or other providers to include out-of-market mergers, or cross-market mergers. Cross-market mergers include the merger or acquisition of any health care entity that does not directly compete with the acquiring entity in the same product or geographic market. Antitrust enforcers have historically had little in the way of market theory, economic models, or empirical data to inform their analyses on the potential impacts of cross-market mergers on competition. However, recent developments in economic theory and empirical studies now offer evidence that cross-market mergers can, in some instances, harm competition and drive price increases in health care markets when a common insurer exists across those markets. This article aims to start a discussion among the health policy and antitrust communities about the potential for cross-market acquisitions to harm competition, whether existing antitrust laws could theoretically support a challenge to a cross-market acquisition, and the practical challenges to doing so. This article will argue that health policy analysts, antitrust enforcers, and academics should begin to consider the anti-competitive potential of cross-market acquisitions and develop a means to analyze them both legally and economically

The ONIOM/PMM Model for Effective Yet Accurate Simulation of Optical and Chiroptical Spectra in Solution: Camphorquinone in Methanol as a Case Study

This paper deals with the development and first validation of a composite approach for the simulation of chiroptical spectra in solution aimed to strongly reduce the number of full QM computations without any significant accuracy loss. The approach starts from the quantum mechanical computation of reference spectra including vibrational averaging effects and taking average solvent effects into account by means of the polarizable continuum model. Next, the snapshots of classical molecular dynamics computations are clusterized and one reference configuration from each cluster is used to compute a reference spectrum. Local fluctuation effects within each cluster are then taken into account by means of the perturbed matrix model. The performance of the proposed approach is tested on the challenging case of the optical and chiroptical spectra of camphorquinone in methanol solution. Although further validations are surely needed, the results of this first study are quite promising also taking into account that agreement with experimental data is reached by just a couple of full quantum mechanical geometry optimizations and frequency computations

The Double-Edged Sword of Health Care Integration: Consolidation and Cost Control

The average family of four in the United States spends $25,826 per year on health care. American health care costs so much because we both overuse and overpay for health care goods and services. The Affordable Care Act\u27s cost control policies focus on curbing overutilization by encouraging health care providers to integrate to promote efficiency and eliminate waste, but the the cost control policies largely ignore prices. This article examines this overlooked half of health care cost control policy: rising prices and the policy levers held by the states to address them. We challenge the conventional wisdom that reducing overutilization through health care integration will effectively reduce health spending. We argue that vertical integration - bringing together disparate providers from hospitals to physicians - is a double-edged sword, with not only the potential to reduce wasteful and unnecessary use of services but also downside risks of increasing market consolidation and health care prices. Due to already highly concentrated health care markets and the limits of federal antitrust enforcement of vertical health care integration, states have both an opportunity and an obligation to supplement federal antitrust efforts to control rising health care prices stemming from health care integration. The way to manage the double-edged sword of health care integration is to require price and quality oversight to avoid harm to competition. We offer a menu of six policy initiatives for states to choose from, ranging from data collection to rate regulation. If we are to control our personal and national health care spending, states have a critical role to play in overseeing health care integration and private health care price increases

CPL Spectra of Camphor Derivatives in Solution by an Integrated QM/MD Approach

We extend a recently proposed computational strategy for the simulation of absorption spectra of semi-rigid molecular systems in condensed phases to the emission spectra of flexible chromophores. As a case study, we have chosen the CPL spectrum of camphor in methanol solution, which shows a well-defined bisignate shape. The first step of our approach is the quantum mechanical computation of reference spectra including vibrational averaging effects and taking bulk solvent effects into account by means of the polarizable continuum model. In the present case, the large amplitude inversion mode is explicitly treated by a numerical approach, whereas the other small-amplitude vibrational modes are taken into account within the harmonic approximation. Next, the snapshots of classical molecular dynamics computations are clusterized and one representative configuration from each cluster is used to compute a reference spectrum. In the present case, different clusters correspond to the two stable conformers of camphor in the S1 excited electronic state and, for each of them, to different numbers of strong solute-solvent hydrogen bonds. Finally, local fluctuation effects within each cluster are taken into account by means of the perturbed matrix model. The overall procedure leads to good agreement with experiment for absorption and emission spectra together with their chiral counterparts, thus allowing to analyze the role of different effects (stereo-electronic, vibrational, environmental) in tuning the overall experimental spectra

Four-electron shell structures and an interacting two-electron system in carbon nanotube quantum dots

Low-temperature transport measurements have been carried out on single-wall carbon nanotube quantum dots in a weakly coupled regime in magnetic fields up to 8 Tesla. Four-electron shell filling was observed, and the magnetic field evolution of each Coulomb peak was investigated, in which magnetic field induced spin flip and resulting spin polarization were observed. Excitation spectroscopy measurements have revealed Zeeman splitting of single particle states for one electron in the shell, and demonstrated singlet and triplet states with direct observation of the exchange splitting at zero-magnetic field for two electrons in the shell, the simplest example of the Hund's rule. The latter indicates the direct analogy to an artificial He atom.Comment: 4 pages, 3 figures, submitted to Physical Review Letter