Two-step phase changes in cubic relaxor ferroelectrics

The field-driven conversion between the zero-field-cooled frozen relaxor state and a ferroelectric state of several cubic relaxors is found to occur in at least two distinct steps, after a period of creep, as a function of time. The relaxation of this state back to a relaxor state under warming in zero field also occurs via two or more sharp steps, in contrast to a one-step relaxation of the ferroelectric state formed by field-cooling. An intermediate state can be trapped by interrupting the polarization. Giant pyroelectric noise appears in some of the non-equilibrium regimes. It is suggested that two coupled types of order, one ferroelectric and the other glassy, may be required to account for these data.Comment: 27 pages with 8 figures to appear in Phys. Rev.

A new species of Hyalella (Crustacea, Amphipoda, Dogielinotidae) from the Atlantic Forest of Misiones, Argentina

The freshwater genus Hyalella Smith, 1874 has a distribution restricted to the Western Hemisphere with most species being found in South America. In this report we describe a new species of Hyalella from the Atlantic Forest of the Misiones province, Argentina.Fil: Colla, Maria Florencia. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División de Zoología Invertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: César, Inés Irma. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División de Zoología Invertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Evaluating the 2013 Euro CAC Experiment

On January 1, 2013, it became mandatory that every new sovereign bond issued by a member of the European Monetary Union include a new contract clause called a Collective Action Clause or CAC. This, we believe, constituted the biggest one-time change to the terms of sovereign debt contracts in history, impacting a market of many trillions of euros. And it was not just that the change was big in terms of the size of the market it impacted; it was big in terms of its impact on the documentation of each individual Euro area sovereign bond contract. To illustrate, prior to January 1, 2013, all of the terms of a local-law Irish sovereign bond fitted on about a page and a half; the full document was about three pages long. After January 1, 2013, the document was twenty pages long; almost all of that space taken by the new CAC term. In terms of words on the page, it was a big change. But did it do anything meaningful? And, more importantly, did it do what it was intended to do

Quantum noise detection: a portable and educational system

Quantum noise is a key feature of laser beams. It is both a limiting effect in contemporary optical measurements and a manifestation of the quantum nature of light. Its properties distinguish it from classical noise. We demonstrate a simple, reliable, and portable apparatus using low cost commercial lasers and electronics that provides evidence of these properties.This work was supported by Centre of Excellence for Quantum-Atom Optics of the Australian Research Council

Performance evaluation in competitive REE models

Our basic premise is that fund managers performance is related to superior information about an asset payoff. We investigate the relationship between managerial skills and trading behavior within a two-period rational expectation equilibrium (REE) model where agents trade on private information in the first round, while a public signal arrives at the second date that makes traders revise their beliefs and retrade. The public signal can be related to the asset payoff, or to variables not related to fundamentals (noise), or both. We characterize the unique partially revealing REE and explore the drivers of price dynamics and trading behavior. Our main prediction is that good managers are contrarian traders, while bad managers are momentum traders when public news arrive to the market. Furthermore, the change in holdings of each type of trader is monotonic on the traders' skills. Based on these predictions, we propose new performance evaluation measures that rely on the manager's change in holdings around the arrival of public news rather than his past performance. A byproduct of our analysis is the proposal of a new protocol for performance evaluation and Due Diligence (DD) procedures.REE; performance evaluation; mutual fund; hedge funds; talent; informed traders; due diligence

Cluster-induced crater formation

Using molecular-dynamics simulation, we study the crater volumes induced by energetic impacts ($v= 1- 250$ km/s) of projectiles containing up to N=1000 atoms. We find that for Lennard-Jones bonded material the crater volume depends solely on the total impact energy $E$. Above a threshold \Eth, the volume rises linearly with $E$. Similar results are obtained for metallic materials. By scaling the impact energy $E$ to the target cohesive energy $U$, the crater volumes become independent of the target material. To a first approximation, the crater volume increases in proportion with the available scaled energy, $V=aE/U$. The proportionality factor $a$ is termed the cratering efficiency and assumes values of around 0.5.Comment: 9 page

The Price of Law: The Case of the Eurozone\u27s Collective Action Clauses

Do markets value contract protections? And does the quality of a legal system affect such valuations? To answer these questions we exploit a unique experiment whereby, after January 1, 2013, newly issued sovereign bonds of Eurozone countries under domestic law had to include Collective Action Clauses (CACs) specifying the minimum vote needed to modify payment terms. We find that CAC bonds trade at lower yields than otherwise similar no-CAC bonds; and that the quality of the legal system matters for this differential. Hence, markets appear to see CACs as providing protection against the legal risk embedded in domestic-law sovereign bonds

The Labor Market Impact of Employer Health Benefit Mandates: Evidence from San Francisco's Health Care Security Ordinance

Examines the impact of a policy requiring employers to provide employee health benefits or contribute to a public option health plan on employment, earnings, and customer surcharges by industry and county

Synchrotron x-ray Studies of Superlattice Ordering in Pb(Mg1/3Nb2/3)O3 Single Crystals Doped with PbTiO3

The temperature dependence of the superlattice reflections: a) F spots and b) alpha spots in a lead magnesium niobate (PMN) single crystals containing 0% and 6% of PbTiO3 (PT) has been studied using synchrotron x-ray scattering techniques. (No superlattice reflections were found in PMN doped with 32% PT). Analysis of the temperature dependence of the alpha spots suggests the existence of the correlated anti-parallel atomic displacements that form nanoregions different from the chemical nanodomains. While the correlation length is temperature independent, the magnitude of these displacements increases on cooling below the freezing temperature Tf. Intensities of the alpha spots above this temperature become indistinguishable from the background. Our results show that value of Tf for each composition is very close to the one obtained from a Vogel-Fulcher fit to the frequency dependence of the dielectric constant maximum Tm. The relation of these correlated anti-ferrodistortive fluctuations to polar ferroelectric nanodomains and relaxor behavior needs further study.Comment: 10 pages, 7 figures, Conference-Fundamental Physics of Ferroelectrics 200

Conservation Conundrum: At-risk Bumble Bees (Bombus spp.) Show Preference for Invasive Tufted Vetch (Vicia cracca) While Foraging in Protected Areas

In recent decades, some bumble bee species have declined, including in North America. Declines have been reported in species of bumble bees historically present in Ontario, including: yellow bumble bee (Bombus fervidus) (Fabricus, 1798), American bumble bee (Bombus pensylvanicus) (DeGeer, 1773), and yellow-banded bumble bee (Bombus terricola) (Kirby, 1837). Threats contributing to bumble bee population declines include: land-use changes, habitat loss, climate change, pathogen spillover, and pesticide use. A response to the need for action on pollinator preservation in North America has been to encourage ‘bee-friendly’ plantings. Previous studies show differences in common and at-risk bumble bee foraging; however, similar data are unavailable for Ontario. Our research question is whether there is a difference in co-occurring at-risk and common bumble bee (Bombus spp.) floral use (including nectar and pollen collection) in protected areas in southern Ontario. We hypothesize that common and at-risk species forage differently, predicting that at-risk species forage on a limited selection of host plants. We conducted a field survey of sites in southern Ontario, using observational methods to determine bumble bee foraging by species. The results of a redundancy analysis show a difference in foraging between common and at-risk bumblebee species. At-risk bumble bee species show a preference for foraging on invasive, naturalized Vicia cracca (tufted vetch). This finding raises the question of how to preserve or provide forage for at-risk bumble bees, when they show an association with an invasive species often subject to control in protected areas.York University Librarie