Sasakian quiver gauge theory on the Aloff-Wallach space X1,1X_{1,1}

We consider the SU(3)-equivariant dimensional reduction of gauge theories on spaces of the form $M^d \times X_{1,1}$ with d-dimensional Riemannian manifold $M^d$ and the Aloff-Wallach space $X_{1,1}$= SU(3)/U(1) endowed with its Sasaki-Einstein structure. The condition of SU(3)-equivariance of vector bundles, which has already occurred in the studies of Spin(7)-instantons on cones over Aloff-Wallach spaces, is interpreted in terms of quiver diagrams, and we construct the corresponding quiver bundles, using (parts of) the weight diagram of SU(3). We consider three examples thereof explicitly and then compare the results with the quiver gauge theory on $Q_3$ =SU(3)/(U(1) x U(1)), the leaf space underlying the Sasaki-Einstein manifold $X_{1,1}$. Moreover, we study instanton solutions on the metric cone $C(X_{1,1})$ by evaluating the Hermitian Yang-Mills equation. We briefly discuss some features of the moduli space thereof, following the main ideas of a treatment of Hermitian Yang-Mills instantons on cones over generic Sasaki-Einstein manifolds in the literature.Comment: 25 page

Are nuclear star clusters the precursors of massive black holes?

We present new upper limits for black hole masses in extremely late type spiral galaxies. We confirm that this class of galaxies has black holes with masses less than 10^6 Msolar, if any. We also derive new upper limits for nuclear star cluster (NC) masses in massive galaxies with previously determined black hole masses. We use the newly derived upper limits and a literature compilation to study the low mass end of the global-to-nucleus relations. We find the following (1) The M_BH-sigma relation cannot flatten at low masses, but may steepen. (2) The M_BH-M_bulge relation may well flatten in contrast. (3) The M_BH-Sersic n relation is able to account for the large scatter in black hole masses in low-mass disk galaxies. Outliers in the M_BH-Sersic n relation seem to be dwarf elliptical galaxies. When plotting M_BH versus M_NC we find three different regimes: (a) nuclear cluster dominated nuclei, (b) a transition region, and (c) black hole-dominated nuclei. This is consistent with the picture, in which black holes form inside nuclear clusters with a very low-mass fraction. They subsequently grow much faster than the nuclear cluster, destroying it when the ratio M_BH/M_NC grows above 100. Nuclear star clusters may thus be the precursors of massive black holes in galaxy nuclei.Comment: This version has a corrected value for Sersic n for NGC205, which got mixed up in the original version. None of the conclusions chang

Trojan Horses or Local Allies: Host-country National Managers in Developing Market Subsidiaries

We investigate a multinational corporation's (MNC) decision to appoint host-country national (HCN) managers to foreign subsidiaries based on the institutional context of and familiarity with the host country. HCN managers are commonly associated with specialized knowledge, superior responsiveness, and higher legitimacy. Yet, we argue that local familiarity of HCNs can also be perceived as risky or harmful by MNC parents. We analyze how formal and informal institutions affect the trade-off between positive effects and potential costs associated with HCN managers ("Local allies" vs. "Trojan horses"). We find that legal institutions protect foreign MNCs from potential costs, encourage the use of HCNs and reinforce their benefits. Corruption and corruption distance, however, increase perceived costs associated with HCN managers up to a point at which they outweigh their perceived benefits

Isometric Immersions and the Waving of Flags

In this article we propose a novel geometric model to study the motion of a physical flag. In our approach a flag is viewed as an isometric immersion from the square with values into $\mathbb R^3$ satisfying certain boundary conditions at the flag pole. Under additional regularity constraints we show that the space of all such flags carries the structure of an infinite dimensional manifold and can be viewed as a submanifold of the space of all immersions. The submanifold result is then used to derive the equations of motion, after equipping the space of isometric immersions with its natural kinetic energy. This approach can be viewed in a similar spirit as Arnold's geometric picture for the motion of an incompressible fluid.Comment: 25 pages, 1 figur

A review of non-pharmacologic approaches to enhance the patient experience in dermatologic surgery

Efforts to increase patient comfort by minimizing pain and anxiety have been shown to improve clinical outcomes, reduce pain thresholds, decrease analgesic requirements and complication risk, strengthen the physician-patient relationship, and increase overall patient satisfaction. Patients also have a strong preference for patient-centered communication and educational discussion with physicians. In recent years, the increasing emphasis on patient experience scores as a metric for quality care has had significant implications for physician practice and has reinforced attempts to provide more patient-centered care. Though different pharmacologic agents and techniques have been extensively reviewed in the dermatologic literature, there have been few studies of non-pharmacologic strategies for improving patient-centered care. This evidence-based review describes alternative techniques that have been suggested for use in dermatologic surgery. Mechanoanesthesia, cold therapy, verbal and audiovisual distraction, music, optimal needle insertion methods, hypnosis and guided-imagery, perioperative communication, and educational strategies have been reported to improve the patient experience in dermatologic surgery. These interventions are often cost-effective and easy to implement, avoid medication side effects, and serve as adjunct approaches to enhance patient comfort. This review examines the corresponding evidence for these nonpharmacologic strategies to provide a clinical resource for the dermatologic surgeon seeking to optimize the patient experience

Perpendicular transport properties of YBa_2Cu_3O_{7-\delta}/PrBa_2Cu_3O_{7-\delta} superlattices

The coupling between the superconducting planes of YBa2Cu3O{7-\delta}/ PrBa2Cu3O{7-\delta} superlattices has been measured by c-axis transport. We show that only by changing the thickness of the superconducting YBa2Cu3O{7-\delta} layers, it is possible to switch between quasi-particle and Josephson tunneling. From our data we deduce a low temperature c-axis coherence length of 0.27 nm.Comment: Presented at LT22, contains 2 pages and 2 figures. to appear in Physica