Properties of Pb(Zr,Ti)O3_3 ultrathin films under stress-free and open-circuit electrical boundary conditions

A first-principles-based scheme is developed to simulate properties of (001) PbO-terminated Pb(Zr$_{1-x}$Ti$_{x}$)O$_3$ thin films that are under stress-free and open-circuit boundary conditions. Their low-temperature spontaneous polarization never vanishes down to the minimal thickness, and continuously rotates between the in-plane and directions when varying the Ti composition around x=0.50. Such rotation dramatically enhances piezoelectricity and dielectricity. Furthermore, the order of some phase transitions changes when going from bulk to thin films.Comment: 11 pages, 3 figure

Observation of genuine three-photon interference

Multiparticle quantum interference is critical for our understanding and exploitation of quantum information, and for fundamental tests of quantum mechanics. A remarkable example of multi-partite correlations is exhibited by the Greenberger-Horne-Zeilinger (GHZ) state. In a GHZ state, three particles are correlated while no pairwise correlation is found. The manifestation of these strong correlations in an interferometric setting has been studied theoretically since 1990 but no three-photon GHZ interferometer has been realized experimentally. Here we demonstrate three-photon interference that does not originate from two-photon or single photon interference. We observe phase-dependent variation of three-photon coincidences with 90.5 \pm 5.0 % visibility in a generalized Franson interferometer using energy-time entangled photon triplets. The demonstration of these strong correlations in an interferometric setting provides new avenues for multiphoton interferometry, fundamental tests of quantum mechanics and quantum information applications in higher dimensions.Comment: 7 pages, 7 figure

The Legalization of the Workplace

This study uses longitudinal data on nearly 300 American employers over the period 1955-85 to analyze the adoption of disciplinary hearings and grievance procedures for nonunion salaried and hourly employees. Hypotheses are developed from an institutional perspective that focuses, first, on uncertainty arising from government mandates concerning equal employment opportunity and affirmative action and, second, on the role of the human relations professions in constructing employment-relations law and prescribing models of compliance. Event-history techniques are used to test these hypotheses against competing arguments concerning the internal structure and labor market position of employing organizations. Results on all outcomes strongly support the institutionalist model.Sociolog

Equal Opportunity Law and the Construction of Internal Labor Markets

Internal labor markets have been explained with efficiency and control arguments; however, retrospective event-history data from 279 organizations suggest that federal Equal Employment Opportunity (EEO) law was the force behind the spread of formal promotion mechanisms after 1964. The findings highlight the way in which American public policy, with its broad outcome-oriented guidelines for organizations, stimulates managers to experiment with compliance mechanisms with an eye to judicial sanction. In response to EEO legislation and case law, personnel managers devised and diffused employment practices that treat all classes of workers as ambitious and achievement oriented in the process of formalizing and rationalizing promotion decisions.Sociolog

Neo-Institutional Theory and Organization Studies: A Mid-Life Crisis?

We trace the development of neo-institutional theory in Organization Studies from a marginal topic to the dominant theory. We show how it has evolved from infancy, through adolescence and early adulthood to being a fully mature theory, which we think is now facing a mid-life crisis. Some of the features of this mid-life crisis include over-reach, myopia, tautology, pseudo-progress and re-inventing the wheel. To address these problems, we argue that institutional theorists should limit the range of the concept, sharpen their lens, avoid tautologies and problematize the concept. By doing this, we think institutional theorists could develop a narrower and more focused conception of institutions

A Near-half-century Simulation of the Solar Corona

We present an overview of results from a magnetofrictional model of the entire solar corona over a period of 47 yr. The simulation self-consistently reproduces decades of solar phenomena, varying in duration between rapid eruptions and the long-term solar cycles, from an input of observed active regions emerging at the photosphere. We have developed a geometric approach to use magnetic helicity to identify and localize the frequent eruptions that occur in the simulation. This method allows us to match our results to extreme-ultraviolet observations of transient events. We have analyzed the evolving magnetic topology by computing the squashing factor and segmenting the corona into discrete magnetic domains bounded by the Separatrix-Web. The simulations show a more dynamic structure to the Separatrix-Web than is predicted by potential field models, which may explain solar wind observations