Good Edge, Bad Edge: How Network Structure Affects a Group’s Ability to Coordinate

Coordination is a core concern in social science. Problems as diverse as deciding where to go to dinner, what price to charge for a good or service, which political candidate to support or what regulatory policy to adopt all contain coordination as a core element. Most coordination problems arise among actors connected in a network, and these connections can both improve and impede a group’s ability to achieve coordination. To model how links influence coordination we distinguish between “constraining edges” that make coordination harder by reducing the number of equilibrium outcomes, and “redundant edges” that make coordination easier by merely increasing communication without affecting the number of equilibria. We show experimentally that the addition of constraining edges reduces coordination, while redundant edges improve subjects’ ability to solve a coordination problem

Electrical conduction mechanisms of metal / high- T c superconductor (YBCO) interfaces

Current-voltage characteristics of Au/YBa2Cu3Ointerfaces (Au/YBCO), built on optimally-doped YBCO thin films, grown by pulsed laser deposition, were measured as a function of temperature in the 50 K to 270 K range, for two different resistance states. A non-trivial equivalent circuit model is proposed, which reveals the existence of a highly inhomogeneous scenario composed by two complex layers: one presenting both a non-linear Poole-Frenkel conduction as well as variable range hopping localization effects (probably associated with YBa2Cu3O6) mixed with a minor metallic phase, while the other is also composed by a mixture of YBCO with different oxygen contents, where a metallic ohmic phase still percolates. A microscopic description of the effects produced by the resistance switching is given, showing the evolution of carrier traps, localization effects and dielectric behavior for each state. The dielectric behavior is interpreted in terms of a Maxwell-Wagner scenario.Fil: Lanosa, Leandro Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Huhtinen, H. University of Turku; FinlandiaFil: Paturi, P. University of Turku; FinlandiaFil: Acha, Carlos Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentin

Angle dependent molecular dynamics simulation of flux pinning in YBCO superconductors with artificial pinning sites

A molecular dynamics (MD) simulation to simulate the vortices in superconductors with artificial pinning sites is presented. The simulation reproduces the correct anisotropic behavior in angular dependence of critical current. We also show that the shape of the J(c)(B) curve depends on the size of the pinning sites and the change from p = 0.5 to p approximate to 1 is due to the breaking of the vortex lattice to individually acting vortices. The results beautifully correspond to experimental data. Furthermore, we found that the size and shape of the c-axis peak observed with columnar pinning sites in J(c)(theta) also depends on the size of the rods, larger pinning sites leading to wider peaks. The results obtained from the MD-simulation are similar to those of the much more computationally intensive Ginzburg-Landau simulations. Furthermore, the MD-simulations can provide insight to the vortex dynamics within the samples

Effect of ex situ Post-annealing Treatments on Sr2FeMoO6 Thin Films

Magnetoresistive Sr2FeMoO6 thin films were grown by pulsed laser deposition at optimized deposition atmosphere and temperature. Films were then ex situ post-annealed in different atmospheres and by vacuum annealing at temperatures between 500 A degrees C and 1100 A degrees C. Ar and air annealed samples were destroyed by ex situ post-annealing treatment, due to formation and dominance of SrMoO4 impurity phase. X-ray diffraction showed no impurities and full texturation of vacuum and ArH2 (5%) annealed samples. Those samples showed also similar magnetic and magnetoresistive behavior like as-deposited sample. Neither magnetic, magnetotransport nor structural properties could be improved by ex situ post-annealing treatments

Transport properties of resistive switching in Ag/Pr0.6Ca0.4MnO3/Al thin film structures

Thin films of Pr0.6Ca0.4MnO3 were prepared by pulsed laser deposition with an asymmetric pair of Ag and Al metal electrodes in order to study their resistive switching properties. The devices exhibited stable voltage controlled bipolar switching which proved to be reliable and non-volatile. The resistive states show a well-defined dependence on the write voltage, which was used to achieve several intermediate states, indicating that the devices could be utilized in hardware implementations of neuromorphic computing. The switching mechanism was attributed to the electric-field assisted migration of oxygen vacancies at the Al-electrode interface, resulting in a formation and modulation of a rectifying interfacial AIO(x) layer. The current-voltage characteristics were analyzed by means of the power exponent representation, which hinted to a device state dependent interplay of bulk-limited Poole-Frenkel conduction and interface-limited Schottky conduction. A deeper understanding of resistive switching characteristics in Ag/Pr0.6Ca0.4MnO3/Al will lead towards further advances in manganite-based neuromorphic circuits. (C) 2019 The Authors. Published by Elsevier B.V

The interpretation of the field angle dependence of the critical current in defect-engineered superconductors

We apply the vortex path model of critical currents to a comprehensive analysis of contemporary data on defect-engineered superconductors, showing that it provides a consistent and detailed interpretation of the experimental data for a diverse range of materials. We address the question of whether electron mass anisotropy plays a role of any consequence in determining the form of this data and conclude that it does not. By abandoning this false interpretation of the data, we are able to make significant progress in understanding the real origin of the observed behavior. In particular, we are able to explain a number of common features in the data including shoulders at intermediate angles, a uniform response over a wide angular range and the greater discrimination between individual defect populations at higher fields. We also correct several misconceptions including the idea that a peak in the angular dependence of the critical current is a necessary signature of strong correlated pinning, and conversely that the existence of such a peak implies the existence of correlated pinning aligned to the particular direction. The consistency of the vortex path model with the principle of maximum entropy is introduced.Comment: 14 pages, 7 figure

Ravitsemuskuntoutuksen toteutuminen Kelan järjestämillä kuntoutuskursseilla

Ravitsemuskuntoutuksella (ravitsemusneuvonta ja ruokatarjonta) on erityisen tärkeä merkitys ravitsemukseen liittyvien sairauksien hoidossa ja ehkäisyssä. Sillä voidaan vaikuttaa myönteisesti myös kuntoutujien toiminta- ja työkykyyn sekä elämänlaatuun. Tutkimuksen tarkoitus oli selvittää, miten ravitsemuskuntoutus toteutetaan eri kuntoutuslaitoksissa. Tutkimuksen erityiskohteiksi valittiin seitsemän erityyppistä kuntoutuskurssia. Tiedot kerättiin sähköisellä kyselylomakkeella. Se lähettiin 55 kuntoutuslaitokseen, joissa toteutetaan Kelan järjestämiä kuntoutuskursseja. Vastaukset saatiin 50 (91 %) laitoksesta. Ravitsemusneuvontaa annettiin 45 laitoksessa. Neuvontaa antoi yleisimmin laillistettu ravitsemusterapeutti (80 %), mutta myös muiden ammattiryhmien edustajat, kuten terveyden- ja sairaanhoitajat sekä lääkärit. Neuvonnan tärkeimmiksi aihepiireiksi vastaajat arvioivat seuraavat: terveellinen ravitsemus yleensä, painonhallinta, säännöllinen ateriarytmi, kuidun riittävä saanti sekä rasvojen laatu ja määrä. Ateriatarjonta vastasi hyvin tai melko hyvin annettua ravitsemusneuvontaa lähes kaikissa laitoksissa. Terveellisen aterian koostaminen havainnollistettiin lautasmallin avulla joka neljännessä laitoksessa. Ravitsemuskuntoutuksen kehittämisehdotuksissa painotettiin ravitsemusneuvonnan ja ruokatarjonnan laadun varmistamista sekä joustavuuden ja asiakaslähtöisyyden lisäämistä. Tulosten perusteella voidaan esittää seuraavaa: Jokaisessa kuntoutuslaitoksessa tulisi olla laillistettu ravitsemusterapeutti, joka vastaa siitä, että ravitsemusneuvonta ja ruokatarjonta ovat ravitsemussuositusten mukaisia. Ruokatarjontaa tulisi kohentaa erityisesti parantamalla rasvojen laatua ja vähentämällä suolan käyttöä ruokien valmistuksessa. Lautasmalli tulisi olla esillä kaikissa laitoksissa esimerkkinä terveellisestä ateriasta. Ravitsemuskuntoutusta koskevia standardeja tulisi tarkentaa ja ravitsemuskuntoutus tulisi ottaa Kelan auditoinnin piiriin.20,00 euro