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Sample records for establishing exchange bias

  1. Establishing exchange bias below T-N with polycrystalline Ni0.52Co0.48O/Co bilayers

    DEFF Research Database (Denmark)

    Berkowitz, A.E.; Hansen, Mikkel Fougt; Tang, Y.J.

    2005-01-01

    Exchange-coupled bilayers of polycrystalline ferromagnetic (FM) Co on antiferromagnetic (AFM) Ni0.52Co0.48O were investigated with emphasis on the issue of establishing an exchange-bias field, H-E, below the AFM ordering temperature, T-N. It was found that field-cooling the bilayers through T......-N provided very little, if any, increase in H-E over that produced by deposition of the Co at temperatures far below T-N. Further significant aspects of this issue were also examined. The biasing field, H-B, needed to be applied only during the deposition of a small fraction (1 nm) of the FM film below T......-N of the AFM to achieve the maximum H-E; if H-B was reversed at any time during the FM deposition, H-E was determined by the final direction of H-B; the direction of H-E could be reversed after it had been established by applying a reversed field during a post-deposition latent period. These and other findings...

  2. Cultural Biases in Economic Exchange

    OpenAIRE

    Luigi Guiso; Paola Sapienza; Luigi Zingales

    2004-01-01

    How much do cultural biases affect economic exchange? We try to answer this question by using the relative trust European citizens have for citizens of other countries. First, we document that this trust is affected not only by objective characteristics of the country being trusted, but also by cultural aspects of the match between trusting country and trusted country, such as religion, history of conflicts, and genetic and somatic similarities. We then find that lower relative...

  3. Development of All Oxide Exchange Bias Systems

    Science.gov (United States)

    Kirkwood, David; Pei, Yonghang; Dao, Nam; Lu, Jiwei; Wolf, Stuart

    2009-03-01

    Multiferroic materials exhibit multiply states of order which are often coupled. Bizmuth Ferrite (BFO3) is a room temperature antiferromagnetic, ferroelectric materials, where electrical control of magnetism and vice versa has been established. Combining BFO3 with ferromagnetic oxides such as Magnetite (Fe3O4) or Lanthanum Strontium Manganate (L.7S.3MO) could yield interesting system with electrically controllable exchange bias. We have used a novel deposition tool employing two pulsed electron beam sources (PEBS) to deposit epitaxial layers of BFO3, LSMO, and Fe3O4 onto STO, LAO, and MgO substrates. We are in the process of making bilayers of these materials and examining the quality and influence of the oxide interface on the development and system control of the exchange bias.

  4. Systematic approach to establishing criticality biases

    International Nuclear Information System (INIS)

    Larson, S.L.

    1995-09-01

    A systematic approach has been developed to determine benchmark biases and apply those biases to code results to meet the requirements of DOE Order 5480.24 regarding documenting criticality safety margins. Previously, validation of the code against experimental benchmarks to prove reasonable agreement was sufficient. However, DOE Order 5480.24 requires contractors to adhere to the requirements of ANSI/ANS-8.1 and establish subcritical margins. A method was developed to incorporate biases and uncertainties from benchmark calculations into a k eff value with quantifiable uncertainty. The method produces a 95% confidence level in both the k eff value of the scenario modeled and the distribution of the k eff S calculated by the Monte Carlo code. Application of the method to a group of benchmarks modeled using the KENO-Va code and the SCALE 27 group cross sections is also presented

  5. Growth of oxide exchange bias layers

    Science.gov (United States)

    Chaiken, A.; Michel, R.P.

    1998-07-21

    An oxide (NiO, CoO, NiCoO) antiferromagnetic exchange bias layer produced by ion beam sputtering of an oxide target in pure argon (Ar) sputtering gas, with no oxygen gas introduced into the system. Antiferromagnetic oxide layers are used, for example, in magnetoresistive readback heads to shift the hysteresis loops of ferromagnetic films away from the zero field axis. For example, NiO exchange bias layers have been fabricated using ion beam sputtering of an NiO target using Ar ions, with the substrate temperature at 200 C, the ion beam voltage at 1000V and the beam current at 20 mA, with a deposition rate of about 0.2 {angstrom}/sec. The resulting NiO film was amorphous. 4 figs.

  6. Angular dependence of the exchange bias for the bistable state

    Energy Technology Data Exchange (ETDEWEB)

    Bai, Yuhao [College of Physics and Electronic Information, Shanxi Normal University, Linfen 041004 (China); Research College of materials science, Shanxi Normal University, Linfen 041004 (China); Xu, Xiaohong, E-mail: xuxh@dns.sxnu.edu.cn [Research College of materials science, Shanxi Normal University, Linfen 041004 (China); Key Laboratory of Magnetic Molecules and Magnetic Information Materials, Ministry of Education, Shanxi Normal University, Linfen 041004 (China)

    2017-06-15

    The angular dependence of the exchange bias (ADEB) has been investigated in detail when the exchange-coupled ferromagnetic (FM)/antiferromagnetic (AFM) bilayer is in the bistable state. Complete and incomplete jump phenomena were found at the intrinsic easy and hard axes, when they pass through two special positions making the angular deviation of 58.2826° and 121.7174° from the easy axis of the uniaxial anisotropy, respectively. The combination of these different types of the jump phenomena at the intrinsic easy and hard axes yields five distinct types of the ADEB. The physical condition for each type of ADEB is established. Additionally, the extreme value problem of the exchange bias field and coercivity are also discussed, which is an important technological issue in the design of the magnetoresistive and spintronic devices. These results enable us to make a comprehensive understanding of the experimental ADEB curves.

  7. Giant exchange bias in MnPd/Co bilayers

    International Nuclear Information System (INIS)

    Nguyen Thanh Nam; Nguyen Phu Thuy; Nguyen Anh Tuan; Nguyen Nguyen Phuoc; Suzuki, Takao

    2007-01-01

    A systematic study of exchange bias in MnPd/Co bilayers has been carried out, where the dependences of exchange bias, unidirectional anisotropy constant and coercivity on the thicknesses of MnPd and Co layers were investigated. A huge unidirectional anisotropy constant, J K =2.5erg/cm 2 was observed, which is in reasonable agreement with the theoretical prediction based on the model by Meiklejohn and Bean. The angular dependences of exchange bias field and coercivity have also been examined showing that both exchange bias and coercivity follow 1/cosα rule

  8. Enhanced exchange bias fields for CoO/Co bilayers: influence of antiferromagnetic grains and mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Cheng-Hsun-Tony; Chang, Shin-Chen [Department of Physics, National Taiwan Normal University, Taipei 116, Taiwan (China); Tsay, Jyh-Shen, E-mail: jstsay@phy.ntnu.edu.tw [Department of Physics, National Taiwan Normal University, Taipei 116, Taiwan (China); Yao, Yeong-Der [Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan (China)

    2017-05-31

    Highlights: • An antiferromagnetic grain model on exchange bias phenomena is proposed. • Grain size and grain density are considered. • For smaller grain size, the dependence of t{sub CoO} on T{sub B} showed a less pronounced variation. • An increased grain density is responsible for the enhancement in the exchange bias fields. - Abstract: The emergence and optimization of devices that can be applied to spintronics have attracted considerable interest, and both experimental and theoretical approaches have been used in studies of exchange bias phenomena. A survey of the literature indicates that great efforts have been devoted to improving exchange bias fields, while only limited attempts have been made to control the temperature dependence of exchange bias. In this study, the influence of antiferromagnetic grains on exchange bias phenomena in CoO/Co bilayers on a semiconductor surface was investigated. Based on an antiferromagnetic grain model, a correlation between grain size, grain density, blocking temperature, and the exchange bias field was established. For crystallites with a smaller median diameter, the dependence of the thickness of the CoO layer on blocking temperature showed a less pronounced variation. This is due to the larger thermal agitation of the atomic spin moments in the grain, which causes a weaker exchange coupling between atomic spin moments. The enhanced density of antiferromagnetic/ferromagnetic pinning sites resulting from an increased grain density is responsible for the enhancement in the exchange bias fields. The results reported herein provide insights into our knowledge related to controlling the temperature dependence of exchange bias and related mechanisms.

  9. Role of the antiferromagnetic bulk spins in exchange bias

    Energy Technology Data Exchange (ETDEWEB)

    Schuller, Ivan K. [Center for Advanced Nanoscience and Physics Department, University of California San Diego, La Jolla, CA 92093 (United States); Morales, Rafael, E-mail: rafael.morales@ehu.es [Department of Chemical-Physics & BCMaterials, University of the Basque Country UPV/EHU (Spain); IKERBASQUE, Basque Foundation for Science, 48011 Bilbao (Spain); Batlle, Xavier [Departament Física Fonamental and Institut de Nanociència i Nanotecnologia, Universitat de Barcelona, c/ Martí i Franqués s/n, 08028 Barcelona, Catalonia (Spain); Nowak, Ulrich [Department of Physics, University of Konstanz, 78464 Konstanz (Germany); Güntherodt, Gernot [Physics Institute (IIA), RWTH Aachen University, Campus RWTH-Melaten, 52074 Aachen (Germany)

    2016-10-15

    This “Critical Focused Issue” presents a brief review of experiments and models which describe the origin of exchange bias in epitaxial or textured ferromagnetic/antiferromagnetic bilayers. Evidence is presented which clearly indicates that inner, uncompensated, pinned moments in the bulk of the antiferromagnet (AFM) play a very important role in setting the magnitude of the exchange bias. A critical evaluation of the extensive literature in the field indicates that it is useful to think of this bulk, pinned uncompensated moments as a new type of a ferromagnet which has a low total moment, an ordering temperature given by the AFM Néel temperature, with parallel aligned moments randomly distributed on the regular AFM lattice. - Highlights: • We address the role of bulk antiferromagnetic spins in the exchange bias phenomenon. • Significant experiments on how bulk AFM spins determine exchange bias are highlighted. • We explain the model that accounts for experimental results.

  10. Mapping domain disorder in exchange-biased magnetic multilayers

    International Nuclear Information System (INIS)

    Marrows, C.H.; Ali, M.; Hindmarch, A.T.; Dekadjevi, D.T.; Hickey, B.J.; Langridge, S.; Foster, S.

    2002-01-01

    Exchange anisotropy occurs at the interface between an antiferromagnetic (AF) layer and a ferromagnetic layer, and results in a ferromagnet hysteresis loop displaced along the field axis. We have performed off-specular neutron reflectometry in order to characterize the domain structure in Co layers that are exchange biased by FeMn. This allows us to determine the domain direction distributions and lateral magnetic correlation lengths for the Co layers as a function of field with the exchange bias in two different thermally prepared states: high field cooled and zero field cooled. We find that a reversing exchange-biased layer is characterized by a very short (submicron) magnetic lengthscale, indicating domains much smaller than those in the ferromagnet after ac demagnetization at temperatures above the blocking temperature. This indicates that the bias is not spatially uniform across the entire interface, underlining the complexity of the AF spin structure

  11. Anisotropy engineering using exchange bias on antidot templates

    Directory of Open Access Journals (Sweden)

    F. J. T. Goncalves

    2015-06-01

    Full Text Available We explore an emerging device concept based on exchange bias used in conjunction with an antidot geometry to fine tune ferromagnetic resonances. Planar cavity ferromagnetic resonance is used to study the microwave response of NiO/NiFe bilayers with antidot structuring. A large frequency asymmetry with respect to an applied magnetic field is found across a broad field range whose underlying cause is linked to the distribution of magnetic poles at the antidot surfaces. This distribution is found to be particularly sensitive to the effects of exchange bias, and robust in regards to the quality of the antidot geometry. The template based antidot geometry we study offers advantages for practical device construction, and we show that it is suitable for broadband absorption and filtering applications, allowing tunable anisotropies via interface engineering.

  12. Theoretical Investigation of Anisotropic Damping in Exchange Bias Systems

    Science.gov (United States)

    Farrar, Alison; Beik Mohammadi, Jamileh; Mewes, Tim; Mewes, Claudia

    An accurate description of the magnetization dynamics of exchange bias systems is essential for further development of computer read heads and STT-MRAM. There have been several theoretical predictions of an anisotropic Gilbert damping tensor, influenced by the symmetry of the crystal structure, in place of the scalar Gilbert damping parameter in the Landau-Lifshitz-Gilbert equation of motion. However, experimental confirmation is difficult as the anisotropy of the damping parameter is expected to be small for single crystals. We follow up on our experimental discovery of a strong unidirectional contribution to the relaxation of exchange bias systems by implementing an anisotropic damping tensor in our Matlab-based micromagnetics code M3. We present results for a damping tensor with unidirectional anisotropy with respect to the instantaneous orientation of the magnetization. NSF-CAREER No 1452670 and 0952929, UA Computer-Based Honors Program.

  13. Exchange bias of patterned systems: Model and numerical simulation

    International Nuclear Information System (INIS)

    Garcia, Griselda; Kiwi, Miguel; Mejia-Lopez, Jose; Ramirez, Ricardo

    2010-01-01

    The magnitude of the exchange bias field of patterned systems exhibits a notable increase in relation to the usual bilayer systems, where a continuous ferromagnetic film is deposited on an antiferromagnet insulator. Here we develop a model, and implement a Monte Carlo calculation, to interpret the experimental observations which is consistent with experimental results, on the basis of assuming a small fraction of spins pinned ferromagnetically in the antiferromagnetic interface layer.

  14. Reversal of exchange bias in nanocrystalline antiferromagnetic-ferromagnetic bilayers

    International Nuclear Information System (INIS)

    Prados, C; Pina, E; Hernando, A; Montone, A

    2002-01-01

    The sign of the exchange bias in field cooled nanocrystalline antiferromagnetic-ferromagnetic bilayers (Co-O and Ni-O/permalloy) is reversed at temperatures approaching the antiferromagnetic (AFM) blocking temperature. A similar phenomenon is observed after magnetic training processes at similar temperatures. These effects can be explained assuming that the boundaries of nanocrystalline grains in AFM layers exhibit lower transition temperatures than grain cores

  15. Robust isothermal electric control of exchange bias at room temperature

    Science.gov (United States)

    Binek, Christian

    2011-03-01

    Voltage-controlled spintronics is of particular importance to continue progress in information technology through reduced power consumption, enhanced processing speed, integration density, and functionality in comparison with present day CMOS electronics. Almost all existing and prototypical solid-state spintronic devices rely on tailored interface magnetism, enabling spin-selective transmission or scattering of electrons. Controlling magnetism at thin-film interfaces, preferably by purely electrical means, is a key challenge to better spintronics. Currently, most attempts to electrically control magnetism focus on potentially large magnetoelectric effects of multiferroics. We report on our interest in magnetoelectric Cr 2 O3 (chromia). Robust isothermal electric control of exchange bias is achieved at room temperature in perpendicular anisotropic Cr 2 O3 (0001)/CoPd exchange bias heterostructures. This discovery promises significant implications for potential spintronics. From the perspective of basic science, our finding serves as macroscopic evidence for roughness-insensitive and electrically controllable equilibrium boundary magnetization in magnetoelectric antiferromagnets. The latter evolves at chromia (0001) surfaces and interfaces when chromia is in one of its two degenerate antiferromagnetic single domain states selected via magnetoelectric annealing. Theoretical insight into the boundary magnetization and its role in electrically controlled exchange bias is gained from first-principles calculations and general symmetry arguments. Measurements of spin-resolved ultraviolet photoemission, magnetometry at Cr 2 O3 (0001) surfaces, and detailed investigations of the unique exchange bias properties of Cr 2 O3 (0001)/CoPd including its electric controllability provide macroscopically averaged information about the boundary magnetization of chromia. Laterally resolved X-ray PEEM and temperature dependent MFM reveal detailed microscopic information of the chromia

  16. Exchange Bias Effects in Iron Oxide-Based Nanoparticle Systems

    Science.gov (United States)

    Phan, Manh-Huong; Alonso, Javier; Khurshid, Hafsa; Lampen-Kelley, Paula; Chandra, Sayan; Stojak Repa, Kristen; Nemati, Zohreh; Das, Raja; Iglesias, Óscar; Srikanth, Hariharan

    2016-01-01

    The exploration of exchange bias (EB) on the nanoscale provides a novel approach to improving the anisotropic properties of magnetic nanoparticles for prospective applications in nanospintronics and nanomedicine. However, the physical origin of EB is not fully understood. Recent advances in chemical synthesis provide a unique opportunity to explore EB in a variety of iron oxide-based nanostructures ranging from core/shell to hollow and hybrid composite nanoparticles. Experimental and atomistic Monte Carlo studies have shed light on the roles of interface and surface spins in these nanosystems. This review paper aims to provide a thorough understanding of the EB and related phenomena in iron oxide-based nanoparticle systems, knowledge of which is essential to tune the anisotropic magnetic properties of exchange-coupled nanoparticle systems for potential applications. PMID:28335349

  17. Exchange bias in diluted-antiferromagnet/antiferromagnet bilayers

    International Nuclear Information System (INIS)

    Mao, Zhongquan; Zhan, Xiaozhi; Chen, Xi

    2015-01-01

    The hysteresis-loop properties of a diluted-antiferromagnetic (DAF) layer exchange coupling to an antiferromagnetic (AF) layer are investigated by means of numerical simulations. Remarkable loop shift and coercivity enhancement are observed in such DAF/AF bilayers, while they are absent in the uncoupled DAF single layer. The influences of pinned domains, dilution, cooling field and DAF layer thickness on the loop shift are investigated systematically. The result unambiguously confirms an exchange bias (EB) effect in the DAF/AF bilayers. It also reveals that the EB effect originates from the pinned AF domains within the DAF layer. In contrast to conventional EB systems, frozen uncompensated spins are not found at the interface of the AF pinning layer. (paper)

  18. Calculations of Exchange Bias in Thin Films with Ferromagnetic/Antiferromagnetic Interfaces

    Science.gov (United States)

    Koon, N. C.

    1997-06-01

    A microscopic explanation of exchange bias in thin films with compensated ferro/antiferromagnetic interfaces is presented. Full micromagnetic calculations show the interfacial exchange coupling to be relatively strong with a perpendicular orientation between the ferro/antiferromagnetic axis directions, similar to the classic ``spin-flop'' state in bulk antiferromagnets. With reasonable parameters the calculations predict bias fields comparable to those observed and provide a possible explanation for both anomalous high field rotational hysteresis and recently discovered ``positive'' exchange bias.

  19. Relative-thickness dependence of exchange bias in bilayers and trilayers

    International Nuclear Information System (INIS)

    Hu Yong; Wu Guozhen; Liu Yan; Du An

    2012-01-01

    We consider the models of ferromagnetic (FM)/antiferromagnetic (AFM) bilayers and trilayers and perform a modified Monte Carlo method to study their exchange bias (EB) properties at low temperature after field cooling on increasing one component thickness at the expense of the other one. The results indicate that EB is insensitive to the thickness variations as the FM layer is thicker than the AFM one. Otherwise, it has a steep increase with the decrease of FM thickness, but the purely inverse proportion is no longer valid due to the dual influences of FM and AFM thicknesses. EB in trilayers should be approximately twice larger than that in bilayers because there is a double interfacial area in the trilayers compared with the bilayers, but the dispersed FM/AFM distributions may break this relation as a result of thermal destabilization. Moreover, EB is independent of FM/AFM stacking sequences probably because of the ideal interface between them. It has been clarified unambiguously that such control of EB through varying the FM/AFM dimensions in heterostructures is attractive for spintronics applications. - Highlights: ► We study ferromagnetic antiferromagnetic dual thickness effects on exchange bias. ► Phenomena observed here violate the empirical law. ► We present a new expression to fit the simulation results successfully. ► We clarify the role of interface in establishing the exchange bias properties.

  20. Annealing temperature dependence of exchange bias in BiFeO3/CoFe bilayers

    Science.gov (United States)

    Yu, T.; Naganuma, H.; Wang, W. X.; Ando, Y.; Han, X. F.

    2012-04-01

    BiFeO3/CoFe bilayers with different BiFeO3 (BFO) crystalities were fabricated by chemical solution deposition and sputtering method. Exchange bias has been successfully induced in these bilayers by post-annealing. The annealing temperature dependence of exchange bias as well as coercivity was investigated. Two kinds of annealing temperature dependence behaviors were observed. It is found that, similar to the conventional antiferromagnet/ferromagnet system, the temperature dependence of exchange bias is dominated by direct interface coupling, and the crystality of BFO has no profound effect on exchange bias.

  1. Simple full micromagnetic model of exchange bias behavior in ferro/antiferromagnetic layered structures (abstract)

    Science.gov (United States)

    Koon, Norman C.

    1997-04-01

    It is shown using full micromagnetic relaxation calculations that exchange bias behavior is predicted for single-crystal ferro/antiferromagnetic layers with a fully compensated interface. The particular example most fully studied has a bcc/bct lattice structure with a fully compensated (110) interface plane. Only bilinear Heisenberg exchange was assumed, with anisotropy only in the antiferromagnet. In spite of the intuitive notion that exchange coupling between a ferromagnet and an antiferromagnet across a fully compensated plane of the antiferromagnet should be zero, we find strong coupling, comparable to the bilinear exchange, with a 90° angle between the ferromagnetic and antiferromagnetic axes of layers far from the interface in absence of an applied field. Even though the 90° coupling has characteristics resembling "biquadratic" exchange, it originates entirely from frustrated bilinear exchange. The development of exchange bias is found to originate from the formation of a domain wall in the antiferromagnet via the strong 90° exchange coupling and pinning of the wall by the magnetocrystalline anisotropy in the antiferromagnet. Because the large demagnetizing factor of the ferromagnet tends to confine its magnetization to the plane, the exchange bias is found to depend mainly on the strength and the symmetry of the in-plane component of anisotropy. Although little effort was made to analyze specific systems, the model reproduces many of the qualitative features observed in real exchange bias systems and gives reasonable semiquantitative estimates for the bias field when exchange and anisotropy values consistent with real systems are used.

  2. Mechanisms of exchange bias with multiferroic BiFeO3 epitaxial thin films

    OpenAIRE

    Bea, H.; Bibes, M.; Ott, F.; Dupe, B.; Zhu, X. -H.; Petit, S.; Fusil, S.; Deranlot, C.; Bouzehouane, K.; Barthelemy, A.

    2007-01-01

    We have combined neutron scattering and piezoresponse force microscopy to study the relation between the exchange bias observed in CoFeB/BiFeO3 heterostructures and the multiferroic domain structure of the BiFeO3 films. We show that the exchange field scales with the inverse of the ferroelectric and antiferromagnetic domain size, as expected from Malozemoff's model of exchange bias extended to multiferroics. Accordingly, polarized neutron reflectometry reveals the presence of uncompensated sp...

  3. Influence of growth conditions on exchange bias of NiMn-based spin valves

    Energy Technology Data Exchange (ETDEWEB)

    Wienecke, Anja; Kruppe, Rahel; Rissing, Lutz [Institute for Microproduction Technology, Leibniz Universität Hannover, 30823 Garbsen (Germany)

    2015-05-07

    As shown in previous investigations, a correlation between a NiMn-based spin valve's thermal stability and its inherent exchange bias exists, even if the blocking temperature of the antiferromagnet is clearly above the heating temperature and the reason for thermal degradation is mainly diffusion and not the loss of exchange bias. Samples with high exchange bias are thermally more stable than samples with low exchange bias. Those structures promoting a high exchange bias are seemingly the same suppressing thermally induced diffusion processes (A. Wienecke and L. Rissing, “Relationship between thermal stability and layer-stack/structure of NiMn-based GMR systems,” in IEEE Transaction on Magnetic Conference (EMSA 2014)). Many investigations were carried out on the influence of the sputtering parameters as well as the layer thickness on the magnetoresistive effect. The influence of these parameters on the exchange bias and the sample's thermal stability, respectively, was hardly taken into account. The investigation described here concentrates on the last named issue. The focus lies on the influence of the sputtering parameters and layer thickness of the “starting layers” in the stack and the layers forming the (synthetic) antiferromagnet. This paper includes a guideline for the evaluated sputtering conditions and layer thicknesses to realize a high exchange bias and presumably good thermal stability for NiMn-based spin valves with a synthetic antiferromagnet.

  4. The Skill-Biased Effects of Exchange Rate Fluctuations

    OpenAIRE

    Boris Kaiser; Michael Siegenthaler

    2015-01-01

    This paper examines the linkages between real exchange rate movements and firms' skill demand. Real exchange rate movements may affect unskilled workers differently than skilled workers because of skill-specific adjustment costs, or because exchange rates lead to changes in relative factor prices and firms' competition intensity. Using panel data on Swiss manufacturers, we find that an appreciation increases high-skilled and reduces low-skilled employment in most firms, while total employment...

  5. Giant parallel and perpendicular exchange biases in MnPd/Co bilayers

    International Nuclear Information System (INIS)

    Thuy, Nguyen Phu; Tuan, Nguyen Anh; Phuoc, Nguyen Nguyen; Suzuki, Takao; Nam, Nguyen Thanh

    2007-01-01

    A systematic study of exchange bias in MnPd/Co bilayers has been carried out in both parallel and perpendicular directions, where the dependences of blocking temperature, exchange bias and unidirectional anisotropy constant on the thicknesses of MnPd and Co layers were investigated. One of the particular interests is that the blocking temperature of parallel exchange bias is higher than that of perpendicular exchange bias which can be interpreted as the difference of the ordering in parallel and perpendicular direction. The other is that a huge unidirectional anisotropy constant, J K =5.5 erg/cm 2 was observed, which is in reasonable agreement with the theoretical prediction based on the model by Meiklejohn and Bean. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  6. Strong exchange bias with the (110)-oriented BiFeO3 films

    Science.gov (United States)

    Bai, Feiming; Yu, Guo; Wang, Yicheng; Jin, Lichuan; Zeng, Huizhong; Tang, Xiaoli; Zhong, Zhiyong; Zhang, Huaiwu

    2012-08-01

    Epitaxial BiFeO3 films were grown on the (001)-, (110)-, and (111)-oriented SrTiO3 substrates. Using CoFe as ferromagnetic layer, we have shown that both large exchange bias and coercive field enhancement can be observed in the (001)- and (110)-oriented BiFeO3. But no exchange bias was found in the (111)-oriented BiFeO3 films, which can be understood by the lack of either 109° or 71° ferroelectric domain walls and the preservation of the spatial modulated cycloid spin structure. The observation of large exchange bias field with the (110)-oriented BiFeO3 film may lead to an alternative choice towards reversible control exchange bias by electrical field.

  7. Nanoscale Control of Exchange Bias with BiFeO3 Thin Films

    NARCIS (Netherlands)

    Martin, Lane W.; Chu, Ying-Hao; Holcomb, Mikel B.; Huijben, Mark; Yu, Pu; Han, Shu-Jen; Lee, Donkoun; Wang, Shan X.; Ramesh, R.

    2008-01-01

    We demonstrate a direct correlation between the domain structure of multiferroic BiFeO3 thin films and exchange bias of Co0.9Fe0.1/BiFeO3 heterostructures. Two distinct types of interactions − an enhancement of the coercive field (exchange enhancement) and an enhancement of the coercive field

  8. Exchange bias and major coercivity enhancement in strongly-coupled CuO/Co films

    Science.gov (United States)

    Gamino, M.; de Andrade, A. M. H.; Salazar Cuaila, J. L.; Schmidt, J. E.; Skumryev, V.; Geshev, J.

    2018-03-01

    The exchange-bias properties of ferromagnetic, either Co or Ni, thin films deposited onto polycrystalline multiferroic CuO are investigated. After field cooling, the CuO/Co magnetization hysteresis loops show exchange bias at temperatures lower than 200 K, while the CuO/Ni system exhibits bias below about 5 K only. It is suggested that the exchange bias of CuO/Co is determined mainly by the magnetization reversal that takes place on the descending branch of the loop. Rather high values of both the interface coupling energy, 0.89 erg/cm2, and coercivity, 2.44 kOe, of the CuO/Co film are obtained at 5 K.

  9. Room temperature exchange bias in BiFeO3 / Co-Fe bilayers

    OpenAIRE

    Sterwerf, Christian; Meinert, Markus; Arenholz, Elke; Schmalhorst, Jan-Michael; Reiss, Günter

    2015-01-01

    Thin highly epitaxial BiFeO$_3$ films were prepared on SrTiO$_3$ (100) substrates by reactive magnetron co-sputtering. Detailed MOKE measurements on BiFeO$_3$/Co-Fe bilayers were performed to investigate the exchange bias as a function of the films thicknesses and Co-Fe stoichiometries. We found a maximum exchange bias of H$_{\\mathrm{eb}}$=92 Oe and a coercive field of H$_{\\mathrm{c}}$=89 Oe for a 12.5 nm thick BiFeO$_3$ film with a 2 nm thick Co layer. The unidirectional anisotropy is clearl...

  10. Exchange bias properties in Sr2LnRuO6 (Ln  =  Dy, Ho and Er)

    Science.gov (United States)

    Mohanty, Prachi; Marik, Sourav; Singh, Deepak; Singh, Ravi P.

    2017-12-01

    Herein, we report the exchange bias effect in Sr2 LnRuO6 (Ln  =  Dy, Ho and Er) compounds. These ruthenium-based double perovskite compounds exhibited the exchange bias effect below their AFM ordering temperatures when they cooled in the presence of a magnetic field. Detailed magnetization measurements indicate that the exchange bias properties may associate with the Dzyaloshinskii–Moria (D–M) interactions originated due to the low crystallographic symmetry in these system types.

  11. Ultra-low-pressure sputtering to improve exchange bias and tune linear ranges in spin valves

    Energy Technology Data Exchange (ETDEWEB)

    Tang, XiaoLi, E-mail: tangtang1227@163.com; Yu, You; Liu, Ru; Su, Hua; Zhang, HuaiWu; Zhong, ZhiYong; Jing, YuLan

    2017-05-01

    A series of CoFe/IrMn exchange bilayers was grown by DC-sputtering at different ultra-low argon pressures ranging from 0.008 to 0.1 Pa. This pressure range was one to two orders lower than the normal sputtering pressure. Results revealed that the exchange bias increased from 140 to 250 Oe in CoFe(10 nm)/IrMn (15 nm) bilayers of fixed thickness because of the improved crystalline structure and morphological uniformity of films. Since ferromagnetic /antiferromagnetic (FM/AF) bilayers are always used in linear magnetic sensors as detection layers, the varying exchange bias can successfully achieve tunable linear range in a crossed pinning spin valve. The linear range could be adjustable from −80 Oe – +80 Oe to −150 Oe – +150 Oe on the basis of giant magnetoresistance responses. Therefore, this method provides a simple method to tune the operating range of magnetic field sensors. - Highlights: • Increasing exchange bias was achieved in bilayer at ultra-low-pressure sputtering. • The low void density and smooth surface were achieved in low pressure. • Varying exchange bias achieved tunable linear range in spin valve.

  12. Exchange bias and bistable magneto-resistance states in amorphous TbFeCo thin films

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xiaopu, E-mail: xl6ba@virginia.edu; Ma, Chung T.; Poon, S. Joseph, E-mail: sjp9x@virginia.edu [Department of Physics, University of Virginia, Charlottesville, Virginia 22904 (United States); Lu, Jiwei [Department of Materials Science and Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States); Devaraj, Arun [Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States); Spurgeon, Steven R.; Comes, Ryan B. [Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States)

    2016-01-04

    Amorphous TbFeCo thin films sputter deposited at room temperature on thermally oxidized Si substrate are found to exhibit strong perpendicular magnetic anisotropy. Atom probe tomography, scanning transmission electron microscopy, and energy dispersive X-ray spectroscopy mapping have revealed two nanoscale amorphous phases with different Tb atomic percentages distributed within the amorphous film. Exchange bias accompanied by bistable magneto-resistance states has been uncovered near room temperature by magnetization and magneto-transport measurements. The exchange anisotropy originates from the exchange interaction between the ferrimagnetic and ferromagnetic components corresponding to the two amorphous phases. This study provides a platform for exchange bias and magneto-resistance switching using single-layer amorphous ferrimagnetic thin films that require no epitaxial growth.

  13. Domain-size-dependent exchange bias in Co/LaFeO3

    Energy Technology Data Exchange (ETDEWEB)

    Scholl, A.; Nolting, F.; Seo, J.W.; Ohldag, H.; Stohr, J.; Raoux,S.; Locquet, J.-P.; Fompeyrine, J.

    2004-09-22

    X-ray microscopy using magnetic linear dichroism of a zero-field-grown, multi-domain Co/LaFeO{sub 3} ferromagnet/antiferromagnet sample shows a local exchange bias of random direction and magnitude. A statistical analysis of the local bias of individual, micron-size magnetic domains demonstrates an increasing bias field with decreasing domain size as expected for a random distribution of pinned, uncompensated spins, which are believed to mediate the interface coupling. A linear dependence with the inverse domain diameter is found.

  14. Bridging exchange bias effect in NiO and Ni(core)@NiO(shell) nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Rinaldi-Montes, Natalia, E-mail: nataliarin@gmail.com [Departamento de Física, Universidad de Oviedo, E-33007 Oviedo (Spain); Gorria, Pedro [Departamento de Física & IUTA, EPI, Universidad de Oviedo, E-33203 Gijón (Spain); Martínez-Blanco, David [Servicios Científico-Técnicos, Universidad de Oviedo, E-33006 Oviedo (Spain); Fuertes, Antonio B. [Instituto Nacional del Carbón, CSIC, E-33080 Oviedo (Spain); Fernández Barquín, Luis [CITIMAC, Facultad de Ciencias, Universidad de Cantabria, E-39005 Santander (Spain); Puente-Orench, Inés [Instituto de Ciencia de Materiales de Aragón, CSIC-Universidad de Zaragoza and Institut Laue-Langevin, BP 156, F-38042 Grenoble Cedex 9 (France); Blanco, Jesús A. [Departamento de Física, Universidad de Oviedo, E-33007 Oviedo (Spain)

    2016-02-15

    Among all bi-magnetic core(transition metal)@shell(transition metal oxide) nanoparticles (NPs), Ni@NiO ones show an onset temperature for the exchange bias (EB) effect far below the Néel temperature of bulk antiferromagnetic NiO. In this framework, the role played by the magnetism of NiO at the nanoscale is investigated by comparing the microstructure and magnetic properties of NiO and Ni@NiO NPs. With the aim of bridging the two systems, the diameter of the NiO NPs (~4 nm) is chosen to be comparable to the shell thickness of Ni@NiO ones (~2 nm). The EB effect in Ni@NiO NPs is attributed to the exchange coupling between the core and the shell, with an interfacial exchange energy of ΔE~0.06 erg cm{sup −2}, thus comparable to previous reports on Ni/NiO interfaces both in thin film and NP morphologies. In contrast, the EB detected in NiO NPs is explained in a picture where uncompensated spins located on a magnetically disordered surface shell are exchange coupled to the antiferromagnetic core. In all the studied NPs, the variation of the EB field as a function of temperature is described according to a negative exponential law with a similar decay constant, yielding a vanishing EB effect around T~40–50 K. In addition, the onset temperature for the EB effect in both NiO and Ni@NiO NPs seems to follow a universal dependence with the NiO crystallite size. - Highlights: • Comparison of the exchange bias effect in NiO and Ni(core)@NiO(shell) nanoparticles. • Universal temperature dependence of the exchange bias effect. • Suggested similar physical origin of the effect in both systems. • Size and crystallinity of the NiO shell hold the key for exchange bias properties.

  15. Exchange bias and asymmetric hysteresis loops from a microscopic model of core/shell nanoparticles

    International Nuclear Information System (INIS)

    Iglesias, Oscar; Batlle, Xavier; Labarta, Amilcar

    2007-01-01

    We present Monte Carlo simulations of hysteresis loops of a model of a magnetic nanoparticle with a ferromagnetic core and an antiferromagnetic shell with varying values of the core/shell interface exchange coupling which aim to clarify the microscopic origin of exchange bias observed experimentally. We have found loop shifts in the field direction as well as displacements along the magnetization axis that increase in magnitude when increasing the interfacial exchange coupling. Overlap functions computed from the spin configurations along the loops have been obtained to explain the origin and magnitude of these features microscopically

  16. Epitaxial exchange-bias systems: From fundamentals to future spin-orbitronics

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wei; Krishnan, Kannan M.

    2016-07-01

    Exchange bias has been investigated for more than half a century and several insightful reviews, published around the year 2000, have already summarized many key experimental and theoretical aspects related to this phenomenon. Since then, due to developments in thin-film fabrication and sophisticated characterization methods, exchange bias continues to show substantial advances; in particular, recent studies on epitaxial systems, which is the focus of this review, allow many long-standing mysteries of exchange bias to be unambiguously resolved. The advantage of epitaxial samples lies in the well-defined interface structures, larger coherence lengths, and competing magnetic anisotropies, which are often negligible in polycrystalline samples. Beginning with a discussion of the microscopic spin properties at the ferromagnetic/antiferromagnetic interface, we correlate the details of spin lattices with phenomenological anisotropies, and finally connect the two by introducing realistic measurement approaches and models. We conclude by providing a brief perspective on the future of exchange bias and related studies in the context of the rapidly evolving interest in antiferromagnetic spintronics.

  17. Observation of exchange bias and spin-glass-like ordering in ε-Fe2 ...

    Indian Academy of Sciences (India)

    glass-like ordering, that arises from the freezing of localized frustrated spins. Keywords. Nanoparticles; nitride; exchange bias; spin glass. PACS Nos 75.50.Lk; 75.50.Tt; 75.50.Bb. 1. Introduction. The 3d transition metal nitrides are not extensively studied since they are relatively less stable as compared to oxides due to their ...

  18. Exchange bias and magnetic behaviour of iron nanoclusters prepared by the gas aggregation technique

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Marcos, J., E-mail: sanchej@icmm.csic.es [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, Cantoblanco, 28049 Madrid (Spain); Laguna-Marco, M.A.; Martinez-Morillas, R. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, Cantoblanco, 28049 Madrid (Spain); Jimenez-Villacorta, F. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, Cantoblanco, 28049 Madrid (Spain); SpLine Spanish CRG Beamline at the European Synchrotron Radiation Facilities, ESRF-BP 220-38043 Grenoble Cedex (France); Cespedes, E. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, Cantoblanco, 28049 Madrid (Spain); Menendez, N. [Dep. Quimica-Fisica Aplicada, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Prieto, C. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, Cantoblanco, 28049 Madrid (Spain)

    2012-09-25

    Highlights: Black-Right-Pointing-Pointer Gas aggregation phase technique allows obtaining {alpha}-Fe{sub 2}O{sub 3} nanoparticles. Black-Right-Pointing-Pointer We have reported exchange bias up to 3250 Oe at 2 K. Black-Right-Pointing-Pointer Exchange bias may be tuned by different stoichiometry of {alpha}-Fe{sub 2}O{sub 3} nanoparticles. - Abstract: Iron nanoclusters have been deposited by the gas-phase aggregation technique to form multilayered structures with outstanding exchange-bias (H{sub E}) values up to H{sub E} = 3300 Oe at low temperatures. In order to explain the observed magnetic properties, composition and crystallographic phase have been determined by X-ray absorption spectroscopy. A metal-oxide core-shell arrangement has to be discarded to explain the large obtained values of H{sub E} since structural results show nanoclusters formed by the antiferromagnetic {alpha}-Fe{sub 2}O{sub 3} oxide. Moreover, nanoparticles of few nanometers formed by substoichiometric {alpha}-Fe{sub 2}O{sub 3} explain the observed weak ferromagnetism and let to understand the origin of large exchange bias by the interaction between different spin sublattice configurations provided by the low iron coordination at surface.

  19. Temperature effects in exchange-biased planar Hall sensors for bioapplications

    DEFF Research Database (Denmark)

    Damsgaard, Christian Danvad; Dalslet, Bjarke Thomas; Freitas, S.C.

    2009-01-01

    The temperature dependence of exchange biased planar Hall effect sensors is investigated between T = −10 and 70 °C. It is shown that a single domain model describes the system well and that the temperature coefficient of the low-field sensitivity at T = 25 °C is 0.32%/°C. A procedure for temperat...

  20. Controlling exchange bias in Co-CoOx nanoparticles by oxygen content

    International Nuclear Information System (INIS)

    Kovylina, Miroslavna; Muro, Montserrat GarcIa del; Konstantinovic, Zorica; Iglesias, Oscar; Labarta, AmIlcar; Batlle, Xavier; Varela, Manuel

    2009-01-01

    We report on the occurrence of exchange bias on laser-ablated granular thin films composed of Co nanoparticles embedded in an amorphous zirconia matrix. The deposition method allows one to control the degree of oxidation of the Co particles by tuning the oxygen pressure at the vacuum chamber (from 2 x 10 -5 to 10 -1 mbar). The nature of the nanoparticles embedded in the nonmagnetic matrix is monitored from metallic, ferromagnetic (FM) Co to antiferromagnetic (AFM) CoO x , with a FM/AFM intermediate regime for which the percentage of the AFM phase can be increased at the expense of the FM phase, leading to the occurrence of exchange bias in particles of about 2 nm in size. For an oxygen pressure of about 10 -3 mbar the ratio between the FM and AFM phases is optimum with an exchange bias field of about 900 Oe at 1.8 K. The mutual exchange coupling between the AFM and FM is also at the origin of the induced exchange anisotropy on the FM leading to high irreversible hysteresis loops, and the blocking of the AFM clusters due to proximity to the FM phase.

  1. Effect of substrate and antiferromagnetic film's thickness on exchange-bias field (invited)

    Science.gov (United States)

    Allegranza, Oletta; Chen, Mao-Min

    1993-05-01

    In this work, we studied the effect of different substrates and the thickness dependence of the antiferromagnetic layer on the exchange-bias field, created through interfacial exchange coupling between NiFe and FeMn. The substrates considered were glass and a metallic underlayer, such as Ta, on glass. We noticed different behaviors of the two types of films when annealed in a magnetic field at 240 °C and we carefully looked at their temperature dependence, observing that the blocking temperature, at which the exchange-bias field goes to zero, decreases with increasing FeMn thickness. We also found that, when reducing the antiferromagnetic film's thickness, the exchange-bias field of the annealed NiFe/FeMn structure improves on both types of substrate. Since a low blocking temperature is undesirable, we developed a method to take advantage of the thinner FeMn film's properties and to compensate the decrease in blocking temperature. The FeMn was deposited in two separate layers. The first layer, at the NiFe interface, was sputtered in pure Ar, and the second in an Ar/O2 or Ar/N2 mixture. The advantage of this technique was particularly impressive for films deposited on Ta over glass, where a factor of 2 improvement in exchange bias field was obtained at both room temperature and 80 °C, when compared to the structure with the same total antiferromagnetic material's thickness deposited in one single layer. Blocking temperatures were above 150 °C.

  2. Closed system respirometry may underestimate tissue gas exchange and bias the respiratory exchange ratio (RER).

    Science.gov (United States)

    Malte, Christian Lind; Nørgaard, Simon; Wang, Tobias

    2016-02-01

    Closed respirometry is a commonly used method to measure gas exchange in animals due to its apparent simplicity. Typically, the rates of O2 uptake and CO2 excretion (VO2 and VCO2, respectively) are assumed to be in steady state, such that the measured rates of gas exchange equal those at tissue level. In other words, the respiratory gas exchange ratio (RER) is assumed to equal the respiratory quotient (RQ). However, because the gas concentrations change progressively during closure, the animal inspires air with a progressively increasing CO2 concentration and decreasing O2 concentration. These changes will eventually affect gas exchange causing the O2 and CO2 stores within the animal to change. Because of the higher solubility/capacitance of CO2 in the tissues of the body, VCO2 will be more affected than VO2, and we hypothesize therefore that RER will become progressively underestimated as closure time is prolonged. This hypothesis was addressed by a combination of experimental studies involving closed respirometry on ball pythons (Python regius) as well as mathematical models of gas exchange. We show that increased closed duration of the respirometer reduces RER by up to 13%, and these findings may explain previous reports of RER values being below 0.7. Our model reveals that the maximally possible reduction in RER is determined by the storage capacity of the body for CO2 (product of size and specific capacitance) relative to the respirometer storage capacity. Furthermore, modeling also shows that pronounced ventilatory and circulatory response to hypercapnia can alleviate the reduction in RER. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. The Behavioral Bias of Foreign Debt Usage in Foreign Exchange Risk Management

    DEFF Research Database (Denmark)

    Aabo, Tom

    foreign exchange risk management in medium-sized, non-financial firms in Denmark and find a behavioral bias in the use of foreign debt. Among the firms that are internationally involved (operating revenues, costs and/or assets in foreign currency), on average a quarter of the financial debt is denominated......We investigate the behavioral bias in the use of debt denominated in foreign currency (foreign debt) in managing foreign exchange risks. From a strictly financial (rational) point of view foreign debt and derivates are close substitutes. Whether e.g. a European firm sells forward US dollars against...... distinguishes itself from the use of shortsighted currency derivatives such as forward contracts by not being significantly and positively related to the foreign sales ratio in a multivariate setting. Furthermore, while the degree of matching at the firm level - creating offsetting operating revenues and costs...

  4. Magnetic properties of patterned arrays of exchange-biased IrMn/Co square dots

    International Nuclear Information System (INIS)

    Vinai, G; Moritz, J; Gaudin, G; Prejbeanu, I L; Dieny, B; Vogel, J; Bonfim, M; Lançon, F; Mackay, K

    2013-01-01

    Finite size effects on the exchange-bias properties of patterned antiferromagnetic/ferromagnetic (IrMn/Co) nanodots were investigated experimentally and by numerical simulations. Both the dot lateral dimension (200 × 200 nm 2 –50 × 50 nm 2 ) and ferromagnetic layer thickness (2–25 nm) were varied. Two different behaviours were observed: single-shifted loops with coherent reversal for thin Co layers and double-shifted loops via a multidomain state during magnetization reversal for thicker Co. Atomistic simulations including magnetostatic interactions confirmed the existence of these two different regimes. MOKE measurements, focused on few dots, allowed a quantitative evaluation of dot-to-dot exchange-bias variability, which becomes particularly large in the regime of switching via multidomain state formation. This variability issue is of particular importance in the context of MRAM development and of magnetoresistive heads for hard-disk drives. (paper)

  5. Inverse relation of exchange-bias and coercivity in epitaxial bilayer of double ruthenate perovskites

    Science.gov (United States)

    Eswara Phanindra, V.; Das, Sarmistha; Singh, R. P.; Rana, D. S.

    2018-03-01

    We report observation of exchange bias (EB) field manifesting in the bilayer thin film of SrRuO3 (SRO) in a rare combination with double perovskite Sr2YRuO6 (SYRO) grown on SrTiO3 (100) substrate. From the temperature and cooling field dependence of exchange bias (HEB) and coercive field (HC), we found an anomalous correlation of these two properties in the temperature range of 15–30 K; the HEB decreases while HC increases with increasing temperature. This anomaly along with the disappearance of the HEB points towards the role of spin fluctuations near the blocking temperature. A good agreement of training effect data with various theoretical models, in turn, supports that the EB derived from the geometrically frustrated interfaces involving double perovskites has generic features as well.

  6. Suppression of exchange bias effect in maghemite nanoparticles functionalized with H{sub 2}Y

    Energy Technology Data Exchange (ETDEWEB)

    Guivar, Juan A. Ramos, E-mail: juan.ramos5@unmsm.edu.pe [Faculty of Physical Sciences, National University of San Marcos, P. O. Box 14-0149, Lima, 14 Peru (Peru); Morales, M.A. [Departamento de Física Teórica e Experimental, UFRN, Natal, RN, 59078-970 Brazil (Brazil); Litterst, F. Jochen [Institut für Physik der Kondensierten Materie, Technische Universität Braunschweig, Braunschweig, 38110 Germany (Germany)

    2016-12-15

    The structural, vibrational, morphological and magnetic properties of maghemite (γ-Fe{sub 2}O{sub 3}) nanoparticles functionalized with polar molecules EDTA(or H{sub 4}Y) and H{sub 2}Y are reported. The samples were functionalized before and after total synthesis of γ-Fe{sub 2}O{sub 3} nanoparticles. The molecules are anchored on the monodentate mode on the nanoparticles surface. Transmission electron microscopy (TEM) revealed the formation of maghemite nanoparticles with small diameter of 4 nm for the sample functionalized upon synthesis and 7.6 and 6.9 nm for the samples functionalized with EDTA and H{sub 2}Y after the formation of nanoparticles. Exchange bias phenomena were observed in some of the samples functionalized with EDTA at temperatures below 70 K. The presence of the bias effect was discussed in terms of the formation of a thin layer of a secondary phase like lepidocrocite, and the absence of this effect was explained in terms of the chemisorption of carboxylic groups from EDTA which suppressed the canting. Studies of Mössbauer spectroscopy as a function of temperature showed slow relaxation effects and allowed discussion of the secondary phase. In the M–T curves a maximum around 116 K was associated with this secondary phase also in agreement with the Mössbauer studies. The dynamic properties were studied by AC susceptibility, the out of phase signal revealed a spin glass like regime below 36.5 K. - Highlights: • Coprecipitation in alkaline medium was used for the synthesis of EDTA functionalized small maghemite nanoparticles. • Exchange bias effect was observed due to a thin layer of lepidocrocite like second phase. • The sample coprecipitated in a weak base did not show exchange bias effect. • The bias effect is discussed in terms of suppression of canting due to chemisorption of carboxylic groups from EDTA.

  7. Disclosure of double exchange bias effect in chromium (III) oxide nanoparticles

    Czech Academy of Sciences Publication Activity Database

    Rinaldi-Montes, N.; Gorria, P.; Fuertes, A.B.; Martinez-Blanco, D.; Olivi, L.; Puente-Orench, I.; Alonso, J.M.; Phan, M.-H.; Skrikanth, H.; Martí, Xavier; Blanco, J.A.

    2017-01-01

    Roč. 53, č. 1 (2017), s. 1-4, č. článku 2300204. ISSN 0018-9464 R&D Projects: GA ČR GB14-37427G Institutional support: RVO:68378271 Keywords : antiferromagnetism * exchange bias (EB) * magnetic nanoparticles * magnetoelectric effect Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 1.243, year: 2016

  8. Ultrathin Limit of Exchange Bias Coupling at Oxide Multiferroic/Ferromagnetic Interfaces

    Science.gov (United States)

    2013-07-12

    stabilizers in recording heads based on anisotropic magnetoresistance . [ 11 ] Exchange bias heterostructures based on multiferroic materials...epitaxial layers of LSMO and BFO, which were strained in-plane to the STO (001) substrate. Figure 1 c shows the presence of Kiessig fringes...drastically. This is generally interpreted by considering a strain -induced distortion of MnO 6 octahedra based on the Jahn-Teller distortion theory. [ 39

  9. Anisotropic magnetoresistance and anomalous Nernst effect in exchange biased permalloy/(1 0 0) NiO single-crystal

    Energy Technology Data Exchange (ETDEWEB)

    Holanda, J., E-mail: joseholanda@df.ufpe.br; Maior, D.S.; Azevedo, A.; Rezende, S.M.

    2017-06-15

    Highlights: • We have investigated the anisotropic magnetoresistance (AMR) and the anomalous Nernst effect (ANE) in an exchange-biased bilayer Py/(100) NiO single-Crystal. • The shift of the hysteresis loop, measured with the different techniques, yield approximately the same value of H{sub EB}. • In spite of the measurement techniques be based in different physical phenomena, our results confirm the robustness of the exchange anisotropy at the Py/NiO interface. • The strength of the anomalous Nernst effect for the exchange-biased permalloy film is compared to values measured in non biased films. - Abstract: We have investigated the anisotropic magnetoresistance (AMR) and the anomalous Nernst effect (ANE) in an exchange-biased bilayer consisting of a thin film of permalloy deposited on a single crystal antiferromagnetic NiO (1 0 0). The exchange bias field (H{sub EB}) value was obtained by means of AMR, ANE and magnetization hysteresis measurements. The shift of the hysteresis loop, measured with the three different techniques, yield approximately the same value of H{sub EB.} In spite of the measurement techniques be based in different physical phenomena, our results confirm the robustness of the exchange anisotropy at the Py/NiO interface. The strength of the anomalous Nernst effect for the exchange-biased permalloy film is compared to values measured in non biased films.

  10. Exchange bias of Ni nanoparticles embedded in an antiferromagnetic IrMn matrix

    International Nuclear Information System (INIS)

    Kuerbanjiang, Balati; Herr, Ulrich; Wiedwald, Ulf; Haering, Felix; Ziemann, Paul; Biskupek, Johannes; Kaiser, Ute

    2013-01-01

    The magnetic properties of Ni nanoparticles (Ni-NPs) embedded in an antiferromagnetic IrMn matrix were investigated. The Ni-NPs of 8.4 nm mean diameter were synthesized by inert gas aggregation. In a second processing step, the Ni-NPs were in situ embedded in IrMn films or SiO x films under ultrahigh vacuum (UHV) conditions. Findings showed that Ni-NPs embedded in IrMn have an exchange bias field H EB = 821 Oe at 10 K, and 50 Oe at 300 K. The extracted value of the exchange energy density is 0.06 mJ m −2 at 10 K, which is in good accordance with the results from multilayered thin film systems. The Ni-NPs embedded in SiO x did not show exchange bias. As expected for this particle size, they are superparamagnetic at T = 300 K. A direct comparison of the Ni-NPs embedded in IrMn or SiO x reveals an increase of the blocking temperature from 210 K to around 400 K. The coercivity of the Ni-NPs exchange coupled to the IrMn matrix at 10 K is 8 times larger than the value for Ni-NPs embedded in SiO x . We studied time-dependent remanent magnetization at different temperatures. The relaxation behavior is described by a magnetic viscosity model which reflects a rather flat distribution of energy barriers. Furthermore, we investigated the effects of different field cooling processes on the magnetic properties of the embedded Ni-NPs. Exchange bias values fit to model calculations which correlate the contribution of the antiferromagnetic IrMn matrix to its grain size. (paper)

  11. Fingerprints of surface magnetism in Cr2O3 based exchange bias heterostructures

    Science.gov (United States)

    He, Xi; Wang, Yi; Binek, Ch.

    2009-03-01

    Magnetoelectric materials experienced a recent revival as promising components of novel spintronic devices [1, 2, 3]. Since the magnetoelectric (ME) effect is relativistically small in traditional antiferromagnetic (AF) compounds like Cr2O3 (max. αzz 4ps/m) and also cross-coupling between ferroic order parameters is typically small in the modern multiferroics, it is a challenge to electrically induce sufficient magnetization required for the envisioned device applications. In exchange bias systems the bias field depends critically on the AF interface magnetization. Hence, a strong relation between the latter and the surface magnetization of the free Cr2O3 pinning layer can be expected. Our recent research indicates that there are surface magnetic phase transitions in free Cr2O3 (111) films accompanying surface structural phase transitions. Well defined AF interface magnetization is initialized through ME annealing to T=20K. Subsequently, the interface magnetization is thermally driven through phase transitions at T=120 and 210K. Their effects on the exchange bias are studied in Cr2O3 (111)/CoPt films with the help of polar Kerr and SQUID magnetometry. [1] P. Borisov et al. Phys. Rev. Lett. 94, 117203 (2005). [2] Ch. Binek, B.Doudin, J. Phys. Condens. Matter 17, L39 (2005). [3] R. Ramesh et al. 2007 Nature Materials 6 21. Financial support by NSF through Career DMR-0547887, MRSEC DMR-0820521 and the NRI.

  12. Reversal magnetization, spin reorientation, and exchange bias in YCr O3 doped with praseodymium

    Science.gov (United States)

    Durán, A.; Escamilla, R.; Escudero, R.; Morales, F.; Verdín, E.

    2018-01-01

    Crystal structure, thermal properties, and magnetic properties were studied systematically in Y1 -xP rxCr O3 with 0.0 ≤x ≤0.3 compositions. Magnetic susceptibility and specific-heat measurements show an increase in the antiferromagnetic transition temperature (TN) as Pr is substituted in the Y sites and notable magnetic features are observed below TN. Strong coupling between magnetic and crystalline parameters is observed in a small range of Pr compositions. A small perturbation in the lattice parameters by a Pr ion is sufficient to induce a spin-reorientation transition followed by magnetization reversal to finally induce the exchange-bias effect. The spin-reorientation temperature (TSR) is increased from 35 to 149 K for 0.025 ≤x ≤0.1 compositions. It is found that the Cr spin sublattice rotates continuously from TSR to a new spin configuration at lower temperature. In addition, magnetization reversal is observed at T*˜35 K for x =0.05 up to T*˜63 K for x =0.20 composition. The M -H curves show a negative exchange-bias effect induced by Pr ions, which are observed below 100 K and are more intense at 5 K. At 10 K, the magnetic contribution of the specific heat as well as the ZFC magnetization show the rise of a peak with increasing Pr content. The magnetic anomaly could be associated with the freezing of the Pr magnetic moment randomly distributed at the 4 c crystallographic site. A clear correspondence between spin reorientation, magnetization reversal, and exchange-bias anisotropy with the tilting and octahedral distortion is also discussed.

  13. Modeling of exchange bias in the antiferromagnetic (core)/ferromagnetic (shell) nanoparticles with specialized shapes

    International Nuclear Information System (INIS)

    Hu Yong; Liu Yan; Du An

    2011-01-01

    Zero-field-cooled (ZFC) and field-cooled (FC) hysteresis loops of egg- and ellipsoid-shaped nanoparticles with inverted ferromagnetic (FM)-antiferromagnetic (AFM) core-shell morphologies are simulated using a modified Monte Carlo method, which takes into account both the thermal fluctuations and energy barriers during the rotation of spin. Pronounced exchange bias (EB) fields and reduced coercivities are obtained in the FC hysteresis loops. The analysis of the microscopic spin configurations allows us to conclude that the magnetization reversal occurs by means of the nucleation process during both the ZFC and FC hysteresis branches. The nucleation takes place in the form of 'sparks' resulting from the energy competition and the morphology of the nanoparticle. The appearance of EB in the FC hysteresis loops is only dependent on that the movements of 'sparks' driven by magnetic field at both branches of hysteresis loops are not along the same axis, which is independent of the strength of AFM anisotropy. The tilt of 'spark' movement with respect to the symmetric axis implies the existence of additional unidirectional anisotropy at the AFM/FM interfaces as a consequence of the surplus magnetization in the AFM core, which is the commonly accepted origin of EB. Our simulations allow us to clarify the microscopic mechanisms of the observed EB behavior, not accessible in experiments. - Highlights: → A modified Monte Carlo method considers thermal fluctuations and energy barriers. → Egg and ellipsoid nanoparticles with inverted core-shell morphology are studied. → Pronounced exchange bias fields and reduced coercivities may be detected. → 'Sparks' representing nucleation sites due to energy competition are observed. → 'Sparks' can reflect or check directly and vividly the origin of exchange bias.

  14. Size-dependent effects in exchange-biased planar Hall effect sensor crosses

    DEFF Research Database (Denmark)

    Donolato, Marco; Dalslet, Bjarke Thomas; Damsgaard, Christian Danvad

    2011-01-01

    Exchange-biased planar Hall effect magnetic field sensor crosses with arm width w have been studied as function of w. For large values of w, the magnetic behavior is hysteresis-free and follows the single domain Stoner-Wohlfarth model. When w is decreased, hysteresis is observed in the sensor...... by an increasing magnetic shape anisotropy of the arms of the cross. We propose a simple analytical model that captures the essential physics of the observations and parameterizes the effects of the cross-shape on the central part of the cross. (C) 2011 American Institute of Physics. [doi:10.1063/1.3561364]...

  15. Controlling exchange bias in Co-CoOx nanoparticles by oxygen content

    OpenAIRE

    Kovylina, Miroslavna; del Muro, Montserrat Garcia; Konstantinovic, Zorica; Varela, Manuel; Iglesias, Oscar; Labarta, Amilcar; Batlle, Xavier

    2009-01-01

    We report on the occurrence of exchange bias on laser-ablated granular thin films composed of Co nanoparticles embedded in amorphous zirconia matrix. The deposition method allows controlling the degree of oxidation of the Co particles by tuning the oxygen pressure at the vacuum chamber (from 2x10^{-5} to 10^{-1} mbar). The nature of the nanoparticles embedded in the nonmagnetic matrix is monitored from metallic, ferromagnetic (FM) Co to antiferromagnetic (AFM) CoOx, with a FM/AFM intermediate...

  16. Asymmetrically shaped hysteresis loop in exchange-biased FeNi/FeMn film

    International Nuclear Information System (INIS)

    Gnatchenko, S.L.; Merenkov, D.N.; Bludov, A.N.; Pishko, V.V.; Shakhayeva, Yu.A.; Baran, M.; Szymczak, R.; Novosad, V.A.

    2006-01-01

    The magnetization reversal of the bilayer polycrystalline FeNi(50 A)/FeMn(50 A) film sputtered in a magnetic field has been studied by magnetic and magneto-optical techniques. The external magnetic fields were applied along the easy or hard magnetization axis of the ferromagnetic permalloy layer. The asymmetry of hysteresis loop has been found. Appreciable asymmetry and the exchange bias were observed only in the field applied along the easy axis. The specific features of magnetization reversal were explained within the phenomenological model that involves high-order exchange anisotropy and misalignment of the easy axes of the antiferromagnetic and ferromagnetic layers. It has been shown that the film can exist in one of three equilibrium magnetic states in the field applied along the easy axis. The transitions between these states occur as first-order phase transitions. The observed hysteresis loop asymmetry is related to the existence of the metastable state

  17. Magnetic and exchange bias properties of YCo thin films and IrMn/YCo bilayers

    Science.gov (United States)

    Venkat Narayana, M.; Manivel Raja, M.; Jammalamadaka, S. Narayana

    2018-02-01

    We report on the structural and magnetic properties of YCo thin films and IrMn/YCo bilayers. X-ray diffraction infer that all the films are amorphous in nature. Magnetization versus magnetic field measurements reveal room temperature soft ferromagnetism in all the YCo films. Thin films which were grown at 100 W sputter power with growth rates of 0.677, 0.694 and 0.711 Å/sec show better morphology and composition than 50 W (0.333, 0.444 and 0.277 Å/sec) grown films. Perpendicular exchange bias in as deposited bilayers is evident for IrMn/YCo bilayers. Exchange bias (EB) decreases in case of in plane measurements and enhances for out of plane measurements after perpendicular field annealing. EB is more in case of out of plane direction due to large perpendicular anisotropy in comparison with in plane direction. Above the critical thickness, EB variation is explained on the basis of random field model in the Heisenberg regime, which has been proposed by Malozemoff. Indeed there exists an inverse relationship between EB and IrMn layer thickness. Evidenced vertical shift apart from the horizontal shift for magnetization loops is attributed to frozen magnetic moments in one of the layers at the interface. Present results would prove to be helpful in spintronic device applications.

  18. NiO/Fe(001): Magnetic anisotropy, exchange bias, and interface structure

    Energy Technology Data Exchange (ETDEWEB)

    Mlynczak, E. [Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, 30-239 Krakow (Poland); Luches, P. [S3, Istituto Nanoscienze-CNR, Via G. Campi 213/a, I-41125 Modena (Italy); Valeri, S. [S3, Istituto Nanoscienze-CNR, Via G. Campi 213/a, I-41125 Modena (Italy); Dipartimento di Scienze Fisiche, Matematiche e Informatiche, Universita di Modena e Reggio Emilia, Via G. Campi 213/a, 41100 Modena (Italy); Korecki, J. [Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, 30-239 Krakow (Poland); Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, al.Mickiewicza 30, 30-059 Krakow (Poland)

    2013-06-21

    The magnetic and structural properties of NiO/Fe epitaxial bilayers grown on MgO(001) were studied using magnetooptic Kerr effect (MOKE) and conversion electron Moessbauer spectroscopy (CEMS). The bilayers were prepared under ultra high vacuum conditions using molecular beam epitaxy with oblique deposition. Two systems were compared: one showing the exchange bias (100ML-NiO/24ML-Fe), ML stands for a monolayer, and another where the exchange bias was not observed (50ML-NiO/50ML-Fe). For both, the magnetic anisotropy was found to be complex, yet dominated by the growth-induced uniaxial anisotropy. The training effect was observed for the 100ML-NiO/24ML-Fe system and quantitatively described using the spin glass model. The composition and magnetic state of the interfacial Fe layers were studied using {sup 57}Fe-CEMS. An iron oxide phase (Fe{sup 3+}{sub 4}Fe{sup 2+}{sub 1}O{sub 7}), as thick as 31 A, was identified at the NiO/Fe interface in the as-deposited samples. The ferrimagnetic nature of the interfacial iron oxide film explains the complex magnetic anisotropy observed in the samples.

  19. Exchange bias in finite sized NiO nanoparticles with Ni clusters

    Energy Technology Data Exchange (ETDEWEB)

    Gandhi, Ashish Chhaganlal; Lin, Jauyn Grace, E-mail: jglin@ntu.edu.tw

    2017-02-15

    Structural and magnetic properties of finite sized NiO nanoparticles are investigated with synchrotron X-ray diffraction (XRD), transmission electron microscopy, magnetometer and ferromagnetic resonance (FMR) spectroscopy. A minor Ni phase is detected with synchrotron XRD, attributed to the oxygen defects in the NiO core. A considerable exchange bias of ~100 Oe is observed at 50 K and it drops abruptly and vanishes above 150 K, in association with the reduction of frozen spins. FMR data indicate a strong interaction between ferromagnetic (FM) and antiferromagnetic (AFM) phases below 150 K, consistent with the picture of isolated FM clusters in AFM matrix. - Highlights: • Structural and magnetic properties of finite sized NiO nanoparticles are systematically investigated with several advanced techniques. • A strong interaction between ferromagnetic and antiferromagnetic phases is found below 150 K. • Exchange bias field in finite sized NiO nanoparticles is due to anisotropy energy of Ni clusters over riding the domain wall energy of NiO.

  20. Exchange bias in finite sized NiO nanoparticles with Ni clusters

    International Nuclear Information System (INIS)

    Gandhi, Ashish Chhaganlal; Lin, Jauyn Grace

    2017-01-01

    Structural and magnetic properties of finite sized NiO nanoparticles are investigated with synchrotron X-ray diffraction (XRD), transmission electron microscopy, magnetometer and ferromagnetic resonance (FMR) spectroscopy. A minor Ni phase is detected with synchrotron XRD, attributed to the oxygen defects in the NiO core. A considerable exchange bias of ~100 Oe is observed at 50 K and it drops abruptly and vanishes above 150 K, in association with the reduction of frozen spins. FMR data indicate a strong interaction between ferromagnetic (FM) and antiferromagnetic (AFM) phases below 150 K, consistent with the picture of isolated FM clusters in AFM matrix. - Highlights: • Structural and magnetic properties of finite sized NiO nanoparticles are systematically investigated with several advanced techniques. • A strong interaction between ferromagnetic and antiferromagnetic phases is found below 150 K. • Exchange bias field in finite sized NiO nanoparticles is due to anisotropy energy of Ni clusters over riding the domain wall energy of NiO.

  1. NiO/Fe(001): Magnetic anisotropy, exchange bias, and interface structure

    Science.gov (United States)

    Młyńczak, E.; Luches, P.; Valeri, S.; Korecki, J.

    2013-06-01

    The magnetic and structural properties of NiO/Fe epitaxial bilayers grown on MgO(001) were studied using magnetooptic Kerr effect (MOKE) and conversion electron Mössbauer spectroscopy (CEMS). The bilayers were prepared under ultra high vacuum conditions using molecular beam epitaxy with oblique deposition. Two systems were compared: one showing the exchange bias (100ML-NiO/24ML-Fe), ML stands for a monolayer, and another where the exchange bias was not observed (50ML-NiO/50ML-Fe). For both, the magnetic anisotropy was found to be complex, yet dominated by the growth-induced uniaxial anisotropy. The training effect was observed for the 100ML-NiO/24ML-Fe system and quantitatively described using the spin glass model. The composition and magnetic state of the interfacial Fe layers were studied using 57Fe-CEMS. An iron oxide phase (Fe3+4Fe2+1O7), as thick as 31 Å, was identified at the NiO/Fe interface in the as-deposited samples. The ferrimagnetic nature of the interfacial iron oxide film explains the complex magnetic anisotropy observed in the samples.

  2. Cyanide single-molecule magnets exhibiting solvent dependent reversible "on" and "off" exchange bias behavior

    DEFF Research Database (Denmark)

    Pinkowicz, Dawid; Southerland, Heather I.; Avendaño, Carolina

    2015-01-01

    Co/Os analogue (PPN){[Mn(III)(salphen)(MeOH)]2[Co(III)0.92Os(III)0.08(CN)6]}·7MeOH were undertaken. It was found that all compounds exhibit switchable single-molecule magnet (SMM) and exchange-bias behavior depending on the interstitial methanol content. The pristine (PPN){[Mn(salphen)(MeOH)]2[Os......(CN)6]}·7MeOH (Mn2Os·7MeOH) behaves as an SMM with an effective barrier for the magnetization reversal, (Ueff/kB), of 17.1 K. Upon desolvation, Mn2Os exhibits an increase of Ueff/kB to 42.0 K and an opening of the hysteresis loop observable at 1.8 K. Mn2Os·7MeOH shows also exchange-bias behavior...... with magnetic hysteresis loops exhibiting a shift in the quantum tunneling to 0.25 T from zero-field. The Fe(III) and Ru(III) analogues were prepared as reference compounds for assessing the effect of the 5d versus 4d and 3d metal ions on the SMM properties. These compounds are also SMMs and exhibit similar...

  3. Exchange biasing studied by neutron techniques in Fe3O4/CoO multilayers

    International Nuclear Information System (INIS)

    Van der Zaag, P.J.; Feiner, L.F.; Wolf, R.M.; Gaines, J.M.; Ijiri, Y.; Borchers, J.A.; Erwin, R.W.

    1999-01-01

    Complete text of publication follows. Recently, the interest in exchange biasing (i.e. the coupling between the antiferromagnetic (AF) and ferromagnetic (F) layers) surged, due to its relevance for GMR spin-valves. Using Fe 3 O 4 /CoO as a model system, it is shown how neutron techniques are crucial in unraveling the nature of the coupling at the buried AF-F interface. Neutron diffraction has shown that the coupling at the interface is not collinear as thus far assumed but perpendicular [1], in agreement with the recent theory by Koon [2]. However, further study by a.o. high- and low-angle neutron diffraction shows that no parallel AF domain wall (can) exists within the AF-layer as assumed by Koon. This suggests that the recent theory by Schulthess-Butler, which finds a perpendicular AF-F coupling on the basis of roughness and a perpendicular domain wall formation in the AF [3], might offer a better framework to understand biasing. The issue of T N in ultrathin CoO layers and its connection to the reduction of the blocking temperature observed in biased AF/F bilayers are also discussed. (author)

  4. Left cheek bias for emotion perception, but not expression, is established in children aged 3-7 years.

    Science.gov (United States)

    Lindell, Annukka K; Tenenbaum, Harriet R; Aznar, Ana

    2017-01-01

    As the left hemiface is controlled by the emotion-dominant right hemisphere, emotion is expressed asymmetrically. Portraits showing a model's left cheek consequently appear more emotive. Though the left cheek bias is well established in adults, it has not been investigated in children. To determine whether the left cheek biases for emotion perception and expression are present and/or develop between the ages of 3 and 7 years, 145 children (71 male, 74 female; M age = 65.49 months) completed two experimental tasks: one assessing biases in emotion perception, and the other assessing biases in emotion expression. Regression analysis confirmed that children aged 3-7 years find left cheek portraits happier than right cheek portraits, and age does not predict the magnitude of the bias. In contrast when asked to pose for a photo expressing happiness children did not show a left cheek bias, with logistic regression confirming that age did not predict posing orientations. These findings indicate that though the left cheek bias for emotion perception is established by age 3, a similar bias for emotion expression is not evident by age 7. This implies that tacit knowledge of the left cheek's greater expressivity is not innate but develops in later childhood/adolescence.

  5. Exchange bias coupling in NiO/Ni bilayer tubular nanostructures synthetized by electrodeposition and thermal oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Yu, T., E-mail: work_tian@scu.edu.cn [College of Physical Science and Technology, Sichuan University, Chengdu 610064 (China); Zhang, Z.W.; Xu, Y.H. [College of Physical Science and Technology, Sichuan University, Chengdu 610064 (China); Liu, Y. [Analytical & Testing Center, Sichuan University, Chengdu 610064 (China); Li, W.J. [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190 (China); Nie, Y.; Zhang, X. [College of Physical Science and Technology, Sichuan University, Chengdu 610064 (China); Xiang, G., E-mail: gxiang@scu.edu.cn [College of Physical Science and Technology, Sichuan University, Chengdu 610064 (China)

    2017-05-01

    In this paper, we reported the synthesis of NiO/Ni bilayer nanotubes by electrodeposition and thermal oxidation using anodic aluminum oxide templates. The morphology, structure, chemical composition and magnetic properties, especially magnetic exchange bias induced by subsequent magnetic field cooling, in this one-dimensional antiferromagnetic/ferromagnetic hybrid system were investigated. It was found that the effect of the annealing temperature, which mainly dominated the thickness of the NiO layer, and the annealing time, which mainly dominated the grain size of the NiO, on the exchange bias field showed competitive relationship. The optimized exchange bias field was achieved by the combination of the shorter annealing time and higher annealing temperature. - Highlights: • NiO-Ni bilayer tubular nanotubes were fabricated by electrodeposition and thermal oxidation. • The exchange bias effect in NiO-Ni nanotubes was induced by magnetic field cooling. • The competitive effect of annealing temperature and annealing time on the exchange bias coupling was analyzed.

  6. 75 FR 45584 - Planning and Establishment of State-Level Exchanges; Request for Comments Regarding Exchange...

    Science.gov (United States)

    2010-08-03

    ... taxpayers? 5. What factors are important in establishing minimum requirements for the actuarial value/level... demand for these loans and grants? What kinds of guidance are they likely to need from HHS and what...

  7. Reversible and irreversible temperature-induced changes in exchange-biased planar Hall effect bridge (PHEB) magnetic field sensors

    DEFF Research Database (Denmark)

    Rizzi, G.; Lundtoft, N.C.; Østerberg, F.W.

    2012-01-01

    We investigate the changes of planar Hall effect bridge magnetic field sensors upon exposure to temperatures between 25° C and 90°C. From analyses of the sensor response vs. magnetic fields we extract the exchange bias field Hex, the uniaxial anisotropy field HK and the anisotropic...... magnetoresistance (AMR) of the exchange biased thin film at a given temperature and by comparing measurements carried out at elevated temperatures T with measurements carried out at 25° C after exposure to T, we can separate the reversible from the irreversible changes of the sensor. The results are not only...... relevant for sensor applications but also demonstrate the method as a useful tool for characterizing exchange-biased thin films....

  8. Defect-tuning exchange bias of ferromagnet/antiferromagnet core/shell nanoparticles by numerical study

    International Nuclear Information System (INIS)

    Mao Zhongquan; Chen Xi; Zhan Xiaozhi

    2012-01-01

    The influence of non-magnetic defects on the exchange bias (EB) of ferromagnet (FM)/antiferromagnet (AFM) core/shell nanoparticles is studied by Monte Carlo simulations. It is found that the EB can be tuned by defects in different positions. Defects at both the AFM and FM interfaces reduce the EB field while they enhance the coercive field by decreasing the effective interface coupling. However, the EB field and the coercive field show respectively a non-monotonic and a monotonic dependence on the defect concentration when the defects are located inside the AFM shell, indicating a similar microscopic mechanism to that proposed in the domain state model. These results suggest a way to optimize the EB effect for applications. (paper)

  9. Experimental evidence of spin glass and exchange bias behavior in sputtered grown α-MnO{sub 2} nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Ashwani; Sanger, Amit; Singh, Amit Kumar; Kumar, Arvind [Nanoscience Laboratory, Institute Instrumentation Centre, Indian Institute of Technology Roorkee, Roorkee 247667 (India); Kumar, Mohit [Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 76100 (Israel); Chandra, Ramesh [Nanoscience Laboratory, Institute Instrumentation Centre, Indian Institute of Technology Roorkee, Roorkee 247667 (India)

    2017-07-01

    Highlights: • We have synthesized the α-MnO{sub 2} nanorods by using DC reactive sputtering. • We observed Spin glass and exchange bias behavior at low temperature in sputtered grown α-MnO{sub 2} nanorods. • Exchange bias arises due to exchange coupling of uncompensated FM spins and AFM spins at FM/AFM interface. - Abstract: Here, we present a single-step process to synthesize the α-MnO{sub 2} nanorods forest using reactive DC magnetron sputtering for the application of magnetic memories. The structural and morphological properties of the α-MnO{sub 2} nanorods were systematically studied using numerous analytical techniques, including X-ray diffraction, Raman spectroscopy, field-emission scanning electron microscopy and transmission electron microscopy. The magnetic measurements suggest that the α-MnO{sub 2} nanorods exhibit spin glass and exchange bias behaviour at low temperature. Such low temperature behaviour is explained by the core-shell type structure of nanorods. Antiferromagnetic core and shell of uncompensated ferromagnetic spins leads to the formation of antiferromagnetic/ferromagnetic (AFM/FM) interfaces, which originates exchange bias in the sample.

  10. Phase coexistence and exchange-bias effect in LiM n2O4 nanorods

    Science.gov (United States)

    Zhang, X. K.; Yuan, J. J.; Xie, Y. M.; Yu, Y.; Kuang, F. G.; Yu, H. J.; Zhu, X. R.; Shen, H.

    2018-03-01

    In this paper, the magnetic properties of LiM n2O4 nanorods with an average diameter of ˜100 nm and length of ˜1 μ m are investigated. The temperature dependences of dc and ac susceptibility measurements show that LiM n2O4 nanorods experience multiple magnetic phase transitions upon cooling, i.e., paramagnetic (PM), antiferromagnetic (AFM), canted antiferromagnetic (CAFM), and cluster spin glass (SG). The coexistence between a long-range ordered AFM phase due to a M n4 +-M n4 + interaction and a cluster SG phase originating from frozen AFM clusters at low temperature in LiM n2O4 nanorods is elucidated. Field-cooled hysteresis loops (FC loops) and magnetic training effect (TE) measurements confirm the presence of an exchange-bias (EB) effect in LiM n2O4 nanorods below the Néel temperature (TN˜60 K ) . Furthermore, by analyzing the TE, we conclude that the observed EB effect originates completely from an exchange coupling interaction at the interface between the AFM and cluster SG states. A phenomenological model based on phase coexistence is proposed to interpret the origin of the EB effect below 60 K in the present compound. In turn, the appearance of the EB effect further supports the coexistence of AFM order along with a cluster SG state in LiM n2O4 nanorods.

  11. Exchange bias properties of 140 nm-sized dipolarly interacting circular dots with ultrafine IrMn and NiFe layers

    Energy Technology Data Exchange (ETDEWEB)

    Spizzo, F., E-mail: spizzo@fe.infn.it [Dipartimento di Fisica e Scienze della Terra and CNISM, Università di Ferrara, I-44122 Ferrara (Italy); Tamisari, M. [Dipartimento di Fisica e Scienze della Terra and CNISM, Università di Ferrara, I-44122 Ferrara (Italy); Dipartimento di Fisica e Geologia and CNISM, Università di Perugia, I-06123 Perugia (Italy); Chinni, F.; Bonfiglioli, E. [Dipartimento di Fisica e Scienze della Terra and CNISM, Università di Ferrara, I-44122 Ferrara (Italy); Gerardino, A. [Istituto di Fotonica e Nanotecnologie, CNR, I-00156 Roma (Italy); Barucca, G. [Dipartimento SIMAU, Università Politecnica delle Marche, I-60131 Ancona (Italy); Bisero, D.; Fin, S.; Del Bianco, L. [Dipartimento di Fisica e Scienze della Terra and CNISM, Università di Ferrara, I-44122 Ferrara (Italy)

    2016-02-15

    We studied the exchange bias effect in an array of IrMn(3 nm)/NiFe(3 nm) circular dots (size ~140 nm and center-to-center distance ~200 nm, as revealed by microscopy analyses), prepared on a large area (3×3 mm{sup 2}) by electron beam lithography and lift-off, using dc sputtering deposition. Hysteresis loops were measured by SQUID magnetometer at increasing values of temperature T (in the 5–300 K range) after cooling from 300 K down to 5 K in zero field (ZFC mode) and in a saturating magnetic field (FC mode). The exchange bias effect disappears above T~200 K and, at each temperature, the exchange field H{sub EX} measured in ZFC is substantially lower than the FC one. Micromagnetic calculations indicate that, at room temperature, each dot is in high-remanence ground state, but magnetic dipolar interactions establish a low-remanence configuration of the array as a whole. Hence, at low temperature, following the ZFC procedure, the exchange anisotropy in the dot array is averaged out, tending to zero. However, even the FC values of H{sub EX} and of the coercivity H{sub C} are definitely smaller compared to those measured in a reference continuous film with the same stack configuration (at T=5 K, H{sub EX}~90 Oe and H{sub C}~180 Oe in the dots and H{sub EX}~1270 Oe and H{sub C}~860 Oe in the film). Our explanation is based on the proven glassy magnetic nature of the ultrathin IrMn layer, implying the existence of magnetic correlations among the spins, culminating in a collective freezing below T~100 K. We propose, also by the light of micromagnetic simulations, that the small dot size imposes a spatial constraint on the magnetic correlation length among the IrMn spins so that, even at the lowest temperature, their thermal stability, especially at the dot border, is compromised. - Highlights: • Exchange bias in 140 nm-sized IrMn(3 nm)/NiFe(3 nm) dots much weaker than in a film. • Glassy magnetic nature of the IrMn phase and collective spin freezing at T<100 K

  12. 77 FR 31513 - Patient Protection and Affordable Care Act; Establishment of Exchanges and Qualified Health Plans...

    Science.gov (United States)

    2012-05-29

    ... Exchanges cannot require Navigators to have agent and broker licenses. However, one sentence implies that... inaccurate. The sentence also incorrectly implies that establishing any licensure standards would not be... Memorandum M-07- 16.'' Second, on page 18341, the preamble uses the term ``personally identifiable health...

  13. Reversible and irreversible temperature-induced changes in exchange-biased planar Hall effect bridge (PHEB) magnetic field sensors

    DEFF Research Database (Denmark)

    Rizzi, G.; Lundtoft, N.C.; Østerberg, F.W.

    2012-01-01

    We investigate the changes of planar Hall effect bridge magnetic field sensors upon exposure to temperatures between 25° C and 90°C. From analyses of the sensor response vs. magnetic fields we extract the exchange bias field Hex, the uniaxial anisotropy field HK and the anisotropic magnetoresista...

  14. Microplasma Jet Synthesis of Ni-Fe Oxide Films for Magnetic Exchange Bias and Electrocatalytic Studies

    Science.gov (United States)

    Pebley, Andrew Christian

    Ni-Fe oxides have received significant interest from the scientific community because they have attractive magnetic and electrochemical properties for use in next generation data storage and energy conversion technologies. For example, the NiFe2O4/NiO nanogranular system exhibits the exchange bias effect, a magnetic phenomenon occurring at the interface of a ferro- or ferrimagnet (FM or FiM) and an antiferromagnet (AFM), where the AFM acts to increase the magnetic hardness of the corresponding FM or FiM. Additionally, doping of NiO with Fe has resulted in remarkably high catalytic activities for water splitting, a potential clean energy alternative to fossil fuels. A key challenge in implementing these Ni-Fe oxides for magnetic and electrocatalytic applications is the ability to control film morphology, crystallinity, composition, chemical phase, and doping during synthesis. Moreover, how these physiochemical properties effect magnetic and electrochemical behavior in the Ni-Fe oxide system is not fully understood. This dissertation focuses on the development and use of a novel synthesis technique, known as microplasma (MP) jet-based deposition, for the fabrication of biphasic NiFe2O4 (FiM)/NiO (AFM) and Fe-doped NiO nanostructured films for fundamental studies of exchange bias and electrocatalysis, respectively. The goal of this work was to understand how MP operation and deposition conditions (e.g., precursor composition, flux, substrate temperature, and post-deposition heat treatment) influence Ni-Fe oxide growth and film microstructure. Specifically, the role of composition, phase fraction, grain size, temperature, and interfacial density on exchange bias phenomena in NiFe 2O4/NiO nanogranular films was investigated. MP jets were also used to realize metastable Fe-doped NiO films with high surface area to assess how doping affects the electrochemical properties of NiO for the oxygen evolution reaction (OER). Biphasic NiFe2O4/NiO films of different composition

  15. Giant exchange bias and its angular dependence in Co/CoO core-shell nanowire assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Gandha, Kinjal; Chaudhary, Rakesh P.; Mohapatra, Jeotikanta; Koymen, Ali R.; Liu, J. Ping, E-mail: pliu@uta.edu

    2017-07-12

    The exchange-bias field (H{sub EB}) and its angular dependence are systematically investigated in Co/CoO core-shell nanowire assemblies (∼15 nm in diameter and ∼200 nm in length) consisting of single-crystalline Co core and polycrystalline CoO shell. Giant exchange-bias field (H{sub EB}) up to 2.4 kOe is observed below a blocking temperature (T{sub EB} ∼150 K) in the aligned Co/CoO nanowire assemblies. It is also found that there is an angular dependence between the H{sub EB} and the applied magnetization direction. The H{sub EB} showed a peak at 30° between the applied field and the nanowire aligned direction, which may be attributed to the noncollinear spin orientations at the interface between the ferromagnetic core and the antiferromagnetic shell. This behavior is quantitatively supported by an analytical calculation based on Stoner–Wohlfarth model. This study underlines the importance of the competing magnetic anisotropies at the interface of Co/CoO core-shell nanowires. - Highlights: • Giant exchange bias is observed in oriented Co/CoO core-shell nanowire assemblies. • Study of angular and temperature dependence of the exchange bias effect. • Competing magnetic anisotropies at the interface of Co/CoO core-shell nanowires. • Effect of misaligned spins in FM/AFM interface on angular dependence of exchange bias. • We explain the analytical model that accounts for experimental results.

  16. Magnetic compensation-induced sign reversal of exchange bias in a multi-glass perovskite SmFeO3

    Science.gov (United States)

    De, Chandan; Nayak, Ajaya K.; Nicklas, Michael; Sundaresan, A.

    2017-10-01

    We report an unusual sign reversal of exchange bias (EB) across a magnetic compensation point in an orthorhombic perovskite SmFeO3. A conventional negative EB with a positive vertical magnetization shift is observed below a cluster-glass freezing temperature (Tg ˜ 150 K). Upon further lowering of the temperature, the EB disappears at the magnetic compensation point before reversing its sign to a positive exchange bias below 4 K. The EB effect originates from an interfacial exchange interaction within a cluster glass phase, whereas its sign reversal arises from the reversal of the direction of the net magnetic moment as a result of dominance of Sm3+ over Fe3+ below the compensation temperature. The existence of a multi-glass state is demonstrated by ac-susceptibility and electrical permittivity measurements. A phenomenological model is presented to understand the EB effect and its sign reversal across the compensation point.

  17. Exchange bias in (La,Ca)MnO3 bilayers: influence of cooling process

    International Nuclear Information System (INIS)

    Restrepo-Parra, E; Agudelo, J D; Restrepo, J

    2012-01-01

    The exchange bias (EB) phenomenon in La 2/3 Ca 1/3 MnO 3 /La 1/3 Ca 2/3 MnO 3 bilayers was studied using Monte Carlo simulations combined with the Heisenberg model and the Metropolis algorithm. These simulations were carried out using the model proposed by Kiwi for an uncompensated interface. The Hamiltonian considered several terms corresponding to the nearest neighbor interaction, magnetocrystalline anisotropy and Zeeman effect. Several interactions in the ferromagnetic (FM), antiferromagnetic (AFM) and FM/AFM interface were considered, depending on the type of interacting ion (Mn 3+eg , Mn 3+eg′ or Mn 4+d3 ). The influence of field cooling and cooling temperature on the EB was analyzed and discussed. Regarding the field cooling, it caused an increase in the EB until a certain critical value was reached. After that, its effect was almost negligible. On the other hand, at low values of cooling temperature, not only the EB but also the coercive field were enhanced. (paper)

  18. Bias-Exchange Metadynamics Simulation of Membrane Permeation of 20 Amino Acids

    Directory of Open Access Journals (Sweden)

    Zanxia Cao

    2018-03-01

    Full Text Available Thermodynamics of the permeation of amino acids from water to lipid bilayers is an important first step for understanding the mechanism of cell-permeating peptides and the thermodynamics of membrane protein structure and stability. In this work, we employed bias-exchange metadynamics simulations to simulate the membrane permeation of all 20 amino acids from water to the center of a dipalmitoylphosphatidylcholine (DPPC membrane (consists of 256 lipids by using both directional and torsion angles for conformational sampling. The overall accuracy for the free energy profiles obtained is supported by significant correlation coefficients (correlation coefficient at 0.5–0.6 between our results and previous experimental or computational studies. The free energy profiles indicated that (1 polar amino acids have larger free energy barriers than nonpolar amino acids; (2 negatively charged amino acids are the most difficult to enter into the membrane; and (3 conformational transitions for many amino acids during membrane crossing is the key for reduced free energy barriers. These results represent the first set of simulated free energy profiles of membrane crossing for all 20 amino acids.

  19. Bias-Exchange Metadynamics Simulation of Membrane Permeation of 20 Amino Acids.

    Science.gov (United States)

    Cao, Zanxia; Bian, Yunqiang; Hu, Guodong; Zhao, Liling; Kong, Zhenzhen; Yang, Yuedong; Wang, Jihua; Zhou, Yaoqi

    2018-03-16

    Thermodynamics of the permeation of amino acids from water to lipid bilayers is an important first step for understanding the mechanism of cell-permeating peptides and the thermodynamics of membrane protein structure and stability. In this work, we employed bias-exchange metadynamics simulations to simulate the membrane permeation of all 20 amino acids from water to the center of a dipalmitoylphosphatidylcholine (DPPC) membrane (consists of 256 lipids) by using both directional and torsion angles for conformational sampling. The overall accuracy for the free energy profiles obtained is supported by significant correlation coefficients (correlation coefficient at 0.5-0.6) between our results and previous experimental or computational studies. The free energy profiles indicated that (1) polar amino acids have larger free energy barriers than nonpolar amino acids; (2) negatively charged amino acids are the most difficult to enter into the membrane; and (3) conformational transitions for many amino acids during membrane crossing is the key for reduced free energy barriers. These results represent the first set of simulated free energy profiles of membrane crossing for all 20 amino acids.

  20. Manipulation of Superparamagnetic Beads on Patterned Exchange-Bias Layer Systems for Biosensing Applications.

    Science.gov (United States)

    Ehresmann, Arno; Koch, Iris; Holzinger, Dennis

    2015-11-13

    A technology platform based on a remotely controlled and stepwise transport of an array arrangement of superparamagnetic beads (SPB) for efficient molecular uptake, delivery and accumulation in the context of highly specific and sensitive analyte molecule detection for the application in lab-on-a-chip devices is presented. The near-surface transport of SPBs is realized via the dynamic transformation of the SPBs' magnetic potential energy landscape above a magnetically stripe patterned Exchange-Bias (EB) thin film layer systems due to the application of sub-mT external magnetic field pulses. In this concept, the SPB velocity is dramatically influenced by the magnitude and gradient of the magnetic field landscape (MFL) above the magnetically stripe patterned EB substrate, the SPB to substrate distance, the magnetic properties of both the SPBs and the EB layer system, respectively, as well as by the properties of the external magnetic field pulses and the surrounding fluid. The focus of this review is laid on the specific MFL design in EB layer systems via light-ion bombardment induced magnetic patterning (IBMP). A numerical approach is introduced for the theoretical description of the MFL in comparison to experimental characterization via scanning Hall probe microscopy. The SPB transport mechanism will be outlined in terms of the dynamic interplay between the EB substrate's MFL and the pulse scheme of the external magnetic field.

  1. Interface spins in polycrystalline FeMn/Fe bilayers with small exchange bias

    Science.gov (United States)

    Pires, M. J. M.

    2018-04-01

    The magnetic moments at the interface between ferromagnetic and antiferromagnetic layers play a central role in exchange biased systems, but their behavior is still not completely understood. In this work, the FeMn/Fe interface in polycrystalline thin films has been studied using conversion electron Mössbauer spectroscopy (CEMS), magneto-optic Kerr effect (MOKE) and micromagnetic simulations. Samples were prepared with 57Fe layers at two distinct depths in order to probe the interface and bulk behaviors. At the equilibrium, the interface moments are randomly oriented while the bulk of the Fe layer has an in-plane magnetic anisotropy. Several models for the interface and anisotropies of the layers were used in the simulations of spin configurations and hysteresis loops. From the whole set of simulations, one can conclude the direct analysis of hysteresis curves is not enough to infer whether the interface has a configuration with spins tilted out of the film plane at equilibrium since different choices of parameters provide similar curves. The simulations have also shown the occurrence of spin clusters at the interface is compatible with CEMS and MOKE measurements.

  2. The Effect of Interface Texture on Exchange Biasing in Ni(80)Fe(20)/Ir(20)Mn(80) System.

    Science.gov (United States)

    Chen, Yuan-Tsung

    2009-01-01

    Exchange-biasing phenomenon can induce an evident unidirectional hysteresis loop shift by spin coupling effect in the ferromagnetic (FM)/antiferromagnetic (AFM) interface which can be applied in magnetoresistance random access memory (MRAM) and recording-head applications. However, magnetic properties are the most important to AFM texturing. In this work, top-configuration exchange-biasing NiFe/IrMn(x A) systems have been investigated with three different conditions. From the high-resolution cross-sectional transmission electron microscopy (HR X-TEM) and X-ray diffraction results, we conclude that the IrMn (111) texture plays an important role in exchange-biasing field (H(ex)) and interfacial exchange energy (J(k)). H(ex) and J(k) tend to saturate when the IrMn thickness increases. Moreover, the coercivity (H(c)) dependence on IrMn thickness is explained based on the coupling or decoupling effect between the spins of the NiFe and IrMn layers near the NiFe/IrMn interface. In this work, the optimal values for H(ex) and J(k) are 115 Oe and 0.062 erg/cm(2), respectively.

  3. The Effect of Interface Texture on Exchange Biasing in Ni80Fe20/Ir20Mn80System

    Science.gov (United States)

    2009-01-01

    Exchange-biasing phenomenon can induce an evident unidirectional hysteresis loop shift by spin coupling effect in the ferromagnetic (FM)/antiferromagnetic (AFM) interface which can be applied in magnetoresistance random access memory (MRAM) and recording-head applications. However, magnetic properties are the most important to AFM texturing. In this work, top-configuration exchange-biasing NiFe/IrMn(x Å) systems have been investigated with three different conditions. From the high-resolution cross-sectional transmission electron microscopy (HR X-TEM) and X-ray diffraction results, we conclude that the IrMn (111) texture plays an important role in exchange-biasing field (Hex) and interfacial exchange energy (Jk).HexandJktend to saturate when the IrMn thickness increases. Moreover, the coercivity (Hc) dependence on IrMn thickness is explained based on the coupling or decoupling effect between the spins of the NiFe and IrMn layers near the NiFe/IrMn interface. In this work, the optimal values forHexandJkare 115 Oe and 0.062 erg/cm2, respectively. PMID:20596365

  4. The Effect of Interface Texture on Exchange Biasing in Ni80Fe20/Ir20Mn80System

    Directory of Open Access Journals (Sweden)

    Chen Yuan-Tsung

    2008-01-01

    Full Text Available Abstract Exchange-biasing phenomenon can induce an evident unidirectional hysteresis loop shift by spin coupling effect in the ferromagnetic (FM/antiferromagnetic (AFM interface which can be applied in magnetoresistance random access memory (MRAM and recording-head applications. However, magnetic properties are the most important to AFM texturing. In this work, top-configuration exchange-biasing NiFe/IrMn(x Å systems have been investigated with three different conditions. From the high-resolution cross-sectional transmission electron microscopy (HR X-TEM and X-ray diffraction results, we conclude that the IrMn (111 texture plays an important role in exchange-biasing field (H ex and interfacial exchange energy (J k.H exandJ ktend to saturate when the IrMn thickness increases. Moreover, the coercivity (H c dependence on IrMn thickness is explained based on the coupling or decoupling effect between the spins of the NiFe and IrMn layers near the NiFe/IrMn interface. In this work, the optimal values forH exandJ kare 115 Oe and 0.062 erg/cm2, respectively.

  5. Effect of the strong coupling on the exchange bias field in IrMn/Py/Ru/Co spin valves

    Science.gov (United States)

    Tarazona, H. S.; Alayo, W.; Landauro, C. V.; Quispe-Marcatoma, J.

    2018-01-01

    The IrMn/Py/Ru/Co (Py = Ni81Fe19) spin valves have been produced by sputtering deposition and analyzed by magnetization measurements and a theoretical modelling of their exchange interactions, based on the macro-spin model. The Ru thickness was grown between 6 and 22 Å, which is small enough to promote strong indirect coupling between Py and Co. Results of measurements showed a large and gradual change in the shape of hysteresis loops when the Ru thickness was varied. The theoretical analysis, using numerical calculations based on the gradient conjugate method, provides the exchange coupling constants (bilinear and biquadratic), the exchange anisotropy fields and the magnetic anisotropy fields (uniaxial and rotatable). The exchange bias fields of spin valves were compared to that of a IrMn/Py bilayer. We found that the difference between these fields oscillates with Ru thickness in the same manner as the bilinear coupling constants.

  6. Oscillatory exchange bias and training effects in nanocrystalline Pr0.5Ca0.5MnO3

    Directory of Open Access Journals (Sweden)

    S. Narayana Jammalamadaka

    2012-03-01

    Full Text Available We report on exchange bias effects in 10 nm particles of Pr0.5Ca0.5MnO3 which appear as a result of competing interactions between the ferromagnetic (FM/anti-ferromagnetic (AFM phases. The fascinating new observation is the demonstration of the temperature dependence of oscillatory exchange bias (OEB and is tunable as a function of cooling field strength below the SG phase, may be attributable to the presence of charge/spin density wave (CDW/SDW in the AFM core of PCMO10. The pronounced training effect is noticed at 5 K from the variation of the EB field as a function of number of field cycles (n upon the field cooling (FC process. For n > 1, power-law behavior describes the experimental data well; however, the breakdown of spin configuration model is noticed at n ≥ 1.

  7. Charge ordering and exchange bias behaviors in Co{sub 3}O{sub 4} porous nanoplatelets and nanorings

    Energy Technology Data Exchange (ETDEWEB)

    Debnath, J.C., E-mail: jcd341@uowmail.edu.au [Institute for Frontier Materials, Deakin University, Geelong, VIC 3216 (Australia); Wang, Jianli [Institute for Superconductivity and Electronic Materials, University of Wollongong, Wollongong, NSW 2522 (Australia); Zeng, R. [Institute for Superconductivity and Electronic Materials, University of Wollongong, Wollongong, NSW 2522 (Australia); School of Materials Science and Engineering, Faculty of Science, UNSW, Sydney NSW 2052 (Australia)

    2017-01-01

    We present the synthesis of α-Co{sub 3}O{sub 4} porous nanoplatelets and hexagonal nanorings using microwave-assisted hydrothermal and conventional chemical reaction methods. The x-ray diffraction (XRD) and refinement analyses indicate the α-Co{sub 3}O{sub 4} crystal structure, and the x-ray photoelectron spectrum (XPS) indicates the high purity of the samples. The M–T (including 1/χ–T) curves indicate an antiferromagnetic transition at about 35 K in both kind of samples but the interesting finding was made that a charge-ordered (CO) state appears at 250 K for the nanoplatelets sample whereas it is inattentive for the nanorings. The antiferromagnetic transition temperature T{sub N} is lower than that of the bulk α-Co{sub 3}O{sub 4} single crystal due to the nanosized structures. We observed quite significant exchange bias for nanorings. The exchange bias behavior of the α-Co{sub 3}O{sub 4} hexagonal nanorings is consistent with an antiferromagnetic (AFM) Co{sub 3}O{sub 4} core and spin-glass like shell. - Highlights: ●Charge-ordered state appears for the Co{sub 3}O{sub 4} nanoplatelets but absent for the nanorings. ●Quite significant exchange bias is only observed for Co{sub 3}O{sub 4} nanorings. ●Exchange bias behavior of Co{sub 3}O{sub 4} nanorings is consistent with spin-glass like shell. ●Potential for ultrahigh-density magnetic recording and spin valve devices.

  8. Exchange bias beyond the superparamagnetic blocking temperature of the antiferromagnet in a Ni-NiO nanoparticulate system

    Science.gov (United States)

    Roy, Aparna; De Toro, J. A.; Amaral, V. S.; Muniz, P.; Riveiro, J. M.; Ferreira, J. M. F.

    2014-02-01

    We report magnetic and exchange bias studies on Ni-NiO nanoparticulate systems synthesized by a two-step process, namely, chemical reduction of a Ni salt followed by air annealing of the dried precipitate in the temperature range 400-550 °C. Size of Ni and NiO crystallites as estimated from X-ray diffraction line broadening ranges between 10.5-13.5 nm and 2.3-4 nm, respectively. The magneto-thermal plots (M-T) of these bi-magnetic samples show a well developed peak in the vicinity of 130 K. This has been identified as the superparamagnetic blocking temperature "TB" of NiO. Interestingly, all samples exhibit exchange bias even above their respective NiO blocking temperatures, right up to 300 K, the maximum temperature of measurement. This is in contrast to previous reports since exchange bias requires the antiferromagnetic NiO to have a stable direction of its moment in order to pin the ferromagnet (Ni) magnetization, whereas such stability is unlikely above TB since the NiO is superparamagnetic, its moment flipping under thermal activation. Our observation is elucidated by taking into account the core-shell morphology of the Ni-NiO nanoparticles whereby clustering of some of these nanoparticles connects their NiO shells to form extended continuous regions of NiO, which because of their large size remain blocked at T > TB, with thermally stable spins capable of pinning the Ni cores and giving rise to exchange bias. The investigated samples may thus be envisaged as being constituted of both isolated core-shell Ni-NiO nanoparticles as well as clustered ones, with TB denoting the blocking temperature of the NiO shell of the isolated particles.

  9. Exchange bias effect in Au-Fe3O4 dumbbell nanoparticles induced by the charge transfer from gold

    Science.gov (United States)

    Feygenson, Mikhail; Bauer, John C.; Gai, Zheng; Marques, Carlos; Aronson, Meigan C.; Teng, Xiaowei; Su, Dong; Stanic, Vesna; Urban, Volker S.; Beyer, Kevin A.; Dai, Sheng

    2015-08-01

    We have studied the origin of the exchange bias effect in the Au-Fe3O4 dumbbell nanoparticles in two samples with different sizes of the Au seed nanoparticles (4.1 and 2.7 nm) and same size of Fe3O4 nanoparticles (9.8 nm). The magnetization, small-angle neutron-scattering, synchrotron x-ray diffraction, and scanning transmission electron microscope measurements determined the antiferromagnetic FeO wüstite phase within Fe3O4 nanoparticles, originating at the interface with the Au nanoparticles. The interface between antiferromagnetic FeO and ferrimagnetic Fe3O4 is giving rise to the exchange bias effect. The strength of the exchange bias fields depends on the interfacial area and lattice mismatch between both phases. We propose that the charge transfer from the Au nanoparticles is responsible for a partial reduction of the Fe3O4 into the FeO phase at the interface with Au nanoparticles. The Au-O bonds are formed, presumably across the interface to accommodate an excess of oxygen released during the reduction of magnetite.

  10. Magnetic depth profiling of an exchange bias system: X-ray resonant magnetic reflectivity of FeMn/Co

    Energy Technology Data Exchange (ETDEWEB)

    Brueck, Sebastian; Ferreras-Paz, Valeriano; Goering, Eberhard; Schuetz, Gisela [Max-Planck-Institut fuer Metallforschung, Heisenbergstrasse 3, D-70569 Stuttgart (Germany)

    2007-07-01

    X-ray resonant magnetic reflectivity (XRMR) extends reflectivity by the X-ray magnetic circular dichroism as additional contrast thus providing element selective magnetic depth information. This makes it a perfect tool to investigate magnetic coupling effects in multi-layered systems. Such systems are for example ferromagnet-antiferromagnet bilayers which can show an exchange coupling between the two layers, the so called exchange bias effect. We present results on Co/FeMn bilayers which have been investigated by XRMR at the BESSY II synchrotron, Berlin. The bilayers were prepared by molecular beam epitaxy on a Cu(100) single crystal which ensures epitaxial growth of both FeMn (in the antiferromagnetic phase) and Co. The magnetic depth profile for room temperature and for 120 K is investigated with respect to changes of the exchange coupling.

  11. Direct imaging of cross-sectional magnetization reversal in an exchange-biased CoFeB/IrMn bilayer

    Science.gov (United States)

    Hu, Shuai; Pei, Ke; Wang, Baomin; Xia, Weixing; Yang, Huali; Zhan, Qingfeng; Li, Xiaoguang; Liu, Xincai; Li, Run-Wei

    2018-02-01

    The exchange coupling between ferromagnetic (FM) and antiferromagnetic materials has been intensely studied for fundamental physics and technological applications in various devices. However, the experimental reported magnitudes of exchange coupling are often smaller than that predicted theoretically, and for which the formation of springlike spin structure in the FM layer has been suggested as the cause. However, investigating the spin structure around the interface of exchange-coupled systems is challenging. Here we report the direct imaging of the cross-sectional magnetization reversal and spin structure at the interface of a model exchange-biased CoFeB/IrMn bilayer by a Lorentz transmission electron microscope with electron holography techniques. Through imaging of in situ magnetization reversal and spin structure at the remanent state, the springlike spin structure (either Bloch-wall-like or Néel-wall-like) in the CoFeB layer has been deduced within subnanometer region of the interface. This result puts a strong constraint on the theories of exchange coupling in inhomogeneous magnetic systems.

  12. Exchange bias variations of the seed and top NiFe layers in NiFe/FeMn/NiFe trilayer as a function of seed layer thickness

    International Nuclear Information System (INIS)

    Sankaranarayanan, V.K.; Yoon, S.M.; Kim, C.G.; Kim, C.O.

    2005-01-01

    Development of exchange bias at the seed and top NiFe layers in the NiFe (t nm)/FeMn(10 nm)/NiFe(5 nm) trilayer structure is investigated as a function of seed layer thickness, in the range of 2-20 nm. The seed NiFe layer shows maximum exchange bias at 4 nm seed layer thickness. The bias shows inverse thickness dependence with increasing thickness. The top NiFe layer on the other hand shows only half the bias of the seed layer which is retained even after the sharp fall in seed layer bias. The much smaller bias for the top NiFe layer is related to the difference in crystalline texture and spin orientations at the top FeMn/NiFe interface, in comparison to the bottom NiFe/FeMn interface which grows on a saturated NiFe layer with (1 1 1) orientation

  13. Tunable exchange bias-like effect in patterned hard-soft two-dimensional lateral composites with perpendicular magnetic anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Hierro-Rodriguez, A., E-mail: ahierro@fc.up.pt; Alvarez-Prado, L. M.; Martín, J. I.; Alameda, J. M. [Departamento de Física, Universidad de Oviedo, C/Calvo Sotelo S/N, 33007 Oviedo (Spain); Centro de Investigación en Nanomateriales y Nanotecnología—CINN (CSIC—Universidad de Oviedo—Principado de Asturias), Parque Tecnológico de Asturias, 33428 Llanera (Spain); Teixeira, J. M. [IN-IFIMUP, Departamento de Física e Astronomia, Faculdade de Ciências, Universidade do Porto, Rua Campo Alegre 687, 4169-007 Porto (Portugal); Vélez, M. [Departamento de Física, Universidad de Oviedo, C/Calvo Sotelo S/N, 33007 Oviedo (Spain)

    2014-09-08

    Patterned hard-soft 2D magnetic lateral composites have been fabricated by e-beam lithography plus dry etching techniques on sputter-deposited NdCo{sub 5} thin films with perpendicular magnetic anisotropy. Their magnetic behavior is strongly thickness dependent due to the interplay between out-of-plane anisotropy and magnetostatic energy. Thus, the spatial modulation of thicknesses leads to an exchange coupled system with hard/soft magnetic regions in which rotatable anisotropy of the thicker elements provides an extra tool to design the global magnetic behavior of the patterned lateral composite. Kerr microscopy studies (domain imaging and magneto-optical Kerr effect magnetometry) reveal that the resulting hysteresis loops exhibit a tunable exchange bias-like shift that can be switched on/off by the applied magnetic field.

  14. High thermal stability of the ferrimagnetic moment in exchange biased FeO(core)/spinel(shell) nanocubes

    International Nuclear Information System (INIS)

    Hai, H T; Kura, H; Takahashi, M; Ogawa, T

    2011-01-01

    We demonstrate herein a basic approach to a new type of exchange-coupled iron oxide-based core/shell nanocubes consisting of an antiferromagnetic (AFM) core of ferrous oxide (wustite, FeO) surrounded by a ferrimagnetic (FM) shell of ferrite (spinel, γ-Fe 2 O 3 or Fe 3 O 4 ). By coupling with AFM core, effective blocking temperature of FM moments is strongly enhanced up to Neel temperature (T N = 198 K) of AFM core. This is assigned to contribution of an extra anisotropy induced by exchange bias at the interface between AFM and FM components in the nanocubes. Because of this special coupling structure, the high stability of FM moments can be achieved even at very small volume fraction of AFM with respect to FM matrix, thus significantly eliminate contribution of AFM to the magnetization of whole coupling system, suggesting a new hybrid structure for magnetic devices applications.

  15. Unravelling the tunable exchange bias-like effect in magnetostatically-coupled two dimensional hybrid (hard/soft) composites

    International Nuclear Information System (INIS)

    Hierro-Rodriguez, A; Teixeira, J M; Rodriguez-Rodriguez, G; Rubio, H; Vélez, M; Álvarez-Prado, L M; Martín, J I; Alameda, J M

    2015-01-01

    Hybrid 2D hard-soft composites have been fabricated by combining soft (Co 73 Si 27 ) and hard (NdCo 5 ) magnetic materials with in-plane and out-of-plane magnetic anisotropies, respectively. They have been microstructured in a square lattice of CoSi anti-dots with NdCo dots within the holes. The magnetic properties of the dots allow us to introduce a magnetostatic stray field that can be controlled in direction and sense by their last saturating magnetic field. The magnetostatic interactions between dot and anti-dot layers induce a completely tunable exchange bias-like shift in the system’s hysteresis loops. Two different regimes for this shift are present depending on the lattice parameter of the microstructures. For large parameters, dipolar magnetostatic decay is observed, while for the smaller one, the interaction between the adjacent anti-dot’s characteristic closure domain structures enhances the exchange bias-like effect as clarified by micromagnetic simulations. (paper)

  16. Training-induced inversion of spontaneous exchange bias field on La{sub 1.5}Ca{sub 0.5}CoMnO{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Bufaiçal, L., E-mail: lbufaical@ufg.br [Instituto de Física, Universidade Federal de Goiás, 74001-970 Goiânia, GO (Brazil); Finkler, R.; Coutrim, L.T. [Instituto de Física, Universidade Federal de Goiás, 74001-970 Goiânia, GO (Brazil); Pagliuso, P.G. [Instituto de Física “Gleb Wataghin”, UNICAMP, 13083-859 Campinas, SP (Brazil); Grossi, C.; Stavale, F.; Baggio-Saitovitch, E.; Bittar, E.M. [Centro Brasileiro de Pesquisas Físicas, Rua Dr. Xavier Sigaud 150, 22290-180 Rio de Janeiro, RJ (Brazil)

    2017-07-01

    Highlights: • La{sub 1.5}Ca{sub 0.5}CoMnO{sub 6} exhibits spontaneous exchange bias effect at low temperature. • For successive hysteresis cycles it inverts the shift sign from negative to positive. • For a field cooled hysteresis cycle, the exchange bias effect greatly enhances. • Our results are compared to those of the analogue compound La{sub 1.5}Sr{sub 0.5}CoMnO{sub 6}. - Abstract: In this work we report the synthesis and structural, electronic and magnetic properties of La{sub 1.5}Ca{sub 0.5}CoMnO{sub 6} double-perovskite. This is a re-entrant spin cluster material which exhibits a non-negligible negative exchange bias effect when it is cooled in zero magnetic field from an unmagnetized state down to low temperature. X-ray powder diffraction, X-ray photoelectron spectroscopy and magnetometry results indicate mixed valence state at Co site, leading to competing magnetic phases and uncompensated spins at the magnetic interfaces. We compare the results for this Ca-doped material with those reported for the resemblant compound La{sub 1.5}Sr{sub 0.5}CoMnO{sub 6}, and discuss the much smaller spontaneous exchange bias effect observed for the former in terms of its structural and magnetic particularities. For La{sub 1.5}Ca{sub 0.5}CoMnO{sub 6}, when successive magnetization loops are carried, the spontaneous exchange bias field inverts its sign from negative to positive from the first to the second measurement. We discuss this behavior based on the disorder at the magnetic interfaces, related to the presence of a glassy phase. This compound also exhibits a large conventional exchange bias, for which there is no sign inversion of the exchange bias field for consecutive cycles.

  17. Quantifying biases in non-steady state chamber measurements of soil-atmosphere gas exchange

    Science.gov (United States)

    Limitations of non-steady state (NSS) chamber methods for determining soil-to-atmosphere trace gas exchange rates have been recognized for several decades. Of these limitations, the so-called “chamber effect” is one of the most challenging to overcome. The chamber effect can be defined as the inhere...

  18. Exchange-biased AMR bridges for magnetic field sensing and biosensing

    DEFF Research Database (Denmark)

    Hansen, Mikkel Fougt; Rizzi, Giovanni

    2017-01-01

    We introduce magnetic field sensor bridges that are formed by combinations of stripes of an exchange-pinned magnetic stack displaying anisotropic magnetoresistance. We present a systematic overview on how the stripe geometries can be combined to form sensor bridges with a scalable signal and how...

  19. Methods for preparing polymer-decorated single exchange-biased magnetic nanoparticles for application in flexible polymer-based films

    Directory of Open Access Journals (Sweden)

    Laurence Ourry

    2017-02-01

    Full Text Available Background: Magnetic nanoparticles (NPs must not only be well-defined in composition, shape and size to exhibit the desired properties (e.g., exchange-bias for thermal stability of the magnetization but also judiciously functionalized to ensure their stability in air and their compatibility with a polymer matrix, in order to avoid aggregation which may seriously affect their physical properties. Dipolar interactions between NPs too close to each other favour a collective magnetic glass state with lower magnetization and coercivity because of inhomogeneous and frustrated macrospin cluster freezing. Consequently, tailoring chemically (through surface functionalization and magnetically stable NPs for technological applications is of primary importance.Results: In this work, well-characterized exchange-biased perfectly epitaxial CoxFe3−xO4@CoO core@shell NPs, which were isotropic in shape and of about 10 nm in diameter, were decorated by two different polymers, poly(methyl methacrylate (PMMA or polystyrene (PS, using radical-controlled polymerization under various processing conditions. We compared the influence of the synthesis parameters on the structural and microstructural properties of the resulting hybrid systems, with special emphasis on significantly reducing their mutual magnetic attraction. For this, we followed two routes: the first one consists of the direct grafting of bromopropionyl ester groups at the surface of the NPs, which were previously recovered and redispersed in a suitable solvent. The second route deals with an “all in solution” process, based on the decoration of NPs by oleic acid followed by ligand exchange with the desired bromopropionyl ester groups. We then built various assemblies of NPs directly on a substrate or suspended in PMMA.Conclusion: The alternative two-step strategy leads to better dispersed polymer-decorated magnetic particles, and the resulting nanohybrids can be considered as valuable building

  20. Origins of the Exchange-Bias Phenomenology, Coercivity Enhancement, and Asymmetric Hysteretic Shearing in Core-Surface Smart Nanoparticles

    Directory of Open Access Journals (Sweden)

    Rıza Erdem

    2016-01-01

    Full Text Available We have used a spin-1 Ising model Hamiltonian with dipolar (bilinear, J, quadrupolar (biquadratic, K, and dipolar-quadrupolar (odd, L interactions in pair approximation to investigate the exchange-bias (EB, coercive field, and asymmetric hysteretic shearing properties peculiar to core/surface (C/S composite nanoparticles (NPs. Shifted hysteresis loops with an asymmetry and coercivity enhancement are observed only in the presence of the odd interaction term in the Hamiltonian expression and their magnitudes show strong dependence on the value of L. The observed coercivity and EB in C/S NPs originated from nonzero odd coupling energies and their dependence on temperature (T and particle size (R are also discussed in relation to experimental findings.

  1. Exchange biased FeNi/FeMn bilayers with coercivity and switching field enhanced by FeMn surface oxidation

    Directory of Open Access Journals (Sweden)

    A. V. Svalov

    2013-09-01

    Full Text Available FeNi/FeMn bilayers were grown in a magnetic field and subjected to heat treatments at temperatures of 50 to 350 °C in vacuum or in a gas mixture containing oxygen. In the as-deposited state, the hysteresis loop of 30 nm FeNi layer was shifted. Low temperature annealing leads to a decrease of the exchange bias field. Heat treatments at higher temperatures in gas mixture result in partial oxidation of 20 nm thick FeMn layer leading to a nonlinear dependence of coercivity and a switching field of FeNi layer on annealing temperature. The maximum of coercivity and switching field were observed after annealing at 300 °C.

  2. Effects of phase transformation and interdiffusion on the exchange bias of NiFe/NiMn

    International Nuclear Information System (INIS)

    Lai, Chih-Huang; Lien, W. C.; Chen, F. R.; Kai, J. J.; Mao, S.

    2001-01-01

    The correlation between the exchange field of NiFe/NiMn and the phase transformation of NiMn was investigated. Transmission electron microscopy (TEM) dark-field images, contributed by the order phase of NiMn, were used to identify the location and volume fraction of the order phase. TEM selected area diffraction patterns showed the (110) superlattice diffraction rings of NiMn, verifying the existence of the order phase in the annealed samples. The order volume fraction can be calculated by the dark field image contributed by the (110) diffraction. The exchange field increased almost linearly with increasing order volume fraction. Energy dispersive x-ray spectroscopy attached to TEM indicated that Mn diffused into NiFe for annealing at 280 degreeC, leading to a larger coercivity and small coercivity squareness. Part of the NiMn still maintains the paramagnetic phase even after annealing at 280 degreeC. [copyright] 2001 American Institute of Physics

  3. The Impact of Targeted Data Collection on Nonresponse Bias in an Establishment Survey: A Simulation Study of Adaptive Survey Design

    Directory of Open Access Journals (Sweden)

    McCarthy Jaki

    2017-09-01

    Full Text Available Nonresponse rates have been growing over time leading to concerns about survey data quality. Adaptive designs seek to allocate scarce resources by targeting specific subsets of sampled units for additional effort or a different recruitment protocol. In order to be effective in reducing nonresponse, the identified subsets of the sample need two key features: 1 their probabilities of response can be impacted by changing design features, and 2 once they have responded, this can have an impact on estimates after adjustment. The National Agricultural Statistics Service (NASS is investigating the use of adaptive design techniques in the Crops Acreage, Production, and Stocks Survey (Crops APS. The Crops APS is a survey of establishments which vary in size and, hence, in their potential impact on estimates. In order to identify subgroups for targeted designs, we conducted a simulation study that used Census of Agriculture (COA data as proxies for similar survey items. Different patterns of nonresponse were simulated to identify subgroups that may reduce estimated nonresponse bias when their response propensities are changed.

  4. Extensive and biased intergenomic nonreciprocal DNA exchanges shaped a nascent polyploid genome, Gossypium (cotton).

    Science.gov (United States)

    Guo, Hui; Wang, Xiyin; Gundlach, Heidrun; Mayer, Klaus F X; Peterson, Daniel G; Scheffler, Brian E; Chee, Peng W; Paterson, Andrew H

    2014-08-01

    Genome duplication is thought to be central to the evolution of morphological complexity, and some polyploids enjoy a variety of capabilities that transgress those of their diploid progenitors. Comparison of genomic sequences from several tetraploid (AtDt) Gossypium species and genotypes with putative diploid A- and D-genome progenitor species revealed that unidirectional DNA exchanges between homeologous chromosomes were the predominant mechanism responsible for allelic differences between the Gossypium tetraploids and their diploid progenitors. Homeologous gene conversion events (HeGCEs) gradually subsided, declining to rates similar to random mutation during radiation of the polyploid into multiple clades and species. Despite occurring in a common nucleus, preservation of HeGCE is asymmetric in the two tetraploid subgenomes. At-to-Dt conversion is far more abundant than the reciprocal, is enriched in heterochromatin, is highly correlated with GC content and transposon distribution, and may silence abundant A-genome-derived retrotransposons. Dt-to-At conversion is abundant in euchromatin and genes, frequently reversing losses of gene function. The long-standing observation that the nonspinnable-fibered D-genome contributes to the superior yield and quality of tetraploid cotton fibers may be explained by accelerated Dt to At conversion during cotton domestication and improvement, increasing dosage of alleles from the spinnable-fibered A-genome. HeGCE may provide an alternative to (rare) reciprocal DNA exchanges between chromosomes in heterochromatin, where genes have approximately five times greater abundance of Dt-to-At conversion than does adjacent intergenic DNA. Spanning exon-to-gene-sized regions, HeGCE is a natural noninvasive means of gene transfer with the precision of transformation, potentially important in genetic improvement of many crop plants. Copyright © 2014 by the Genetics Society of America.

  5. 77 FR 18309 - Patient Protection and Affordable Care Act; Establishment of Exchanges and Qualified Health Plans...

    Science.gov (United States)

    2012-03-27

    ... identification, commenters are encouraged to leave their comments in the CMS drop slots located in the main lobby... structure of the Exchange is consistent with Sec. 155.110. Furthermore, we introduced the concept of a State...

  6. The influence of oxidation process on exchange bias in egg-shaped FeO/Fe{sub 3}O{sub 4} core/shell nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Leszczyński, Błażej, E-mail: b.leszczynski@amu.edu.pl [NanoBioMedical Centre, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland); Faculty of Physics, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland); Hadjipanayis, George C.; El-Gendy, Ahmed A. [Department of Physics and Astronomy, University of Delaware, 217 Sharp Lab, Newark, DE 19716 (United States); Załęski, Karol [NanoBioMedical Centre, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland); Śniadecki, Zbigniew [Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, 60-179 Poznań (Poland); Musiał, Andrzej [NanoBioMedical Centre, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland); Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, 60-179 Poznań (Poland); Jarek, Marcin [NanoBioMedical Centre, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland); Jurga, Stefan [NanoBioMedical Centre, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland); Faculty of Physics, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland); Skumiel, Andrzej [Faculty of Physics, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland)

    2016-10-15

    Egg-shaped nanoparticles with a core–shell morphology were synthesized by thermal decomposition of an iron oleate complex. XRD and M(T) magnetic measurements confirmed the presence of FeO (wustite) and Fe{sub 3}O{sub 4} (magnetite) phases in the nanoparticles. Oxidation of FeO to Fe{sub 3}O{sub 4} was found to be the mechanism for the shell formation. As-made nanoparticles exhibited high values of exchange bias at 2 K. Oxidation led to decrease of exchange field from 2880 Oe (in as-made sample) to 330 Oe (in oxidized sample). At temperatures higher than the Néel temperature of FeO (200 K) there was no exchange bias. An interesting observation was made showing the exchange field to be higher than the coercive field at temperatures close to magnetite's Verwey transition. - Highlights: • Synthesis of monodispersed FeO nanoparticles is shown. • As-made FeO nanoparticle is antiferromagnetically ordered, when it is oxidized to Fe{sub 3}O{sub 4}, the FeO core becomes small and disordered. • Exchange bias in well-ordered and disordered core is different.

  7. The influence of oxidation process on exchange bias in egg-shaped FeO/Fe3O4 core/shell nanoparticles

    International Nuclear Information System (INIS)

    Leszczyński, Błażej; Hadjipanayis, George C.; El-Gendy, Ahmed A.; Załęski, Karol; Śniadecki, Zbigniew; Musiał, Andrzej; Jarek, Marcin; Jurga, Stefan; Skumiel, Andrzej

    2016-01-01

    Egg-shaped nanoparticles with a core–shell morphology were synthesized by thermal decomposition of an iron oleate complex. XRD and M(T) magnetic measurements confirmed the presence of FeO (wustite) and Fe 3 O 4 (magnetite) phases in the nanoparticles. Oxidation of FeO to Fe 3 O 4 was found to be the mechanism for the shell formation. As-made nanoparticles exhibited high values of exchange bias at 2 K. Oxidation led to decrease of exchange field from 2880 Oe (in as-made sample) to 330 Oe (in oxidized sample). At temperatures higher than the Néel temperature of FeO (200 K) there was no exchange bias. An interesting observation was made showing the exchange field to be higher than the coercive field at temperatures close to magnetite's Verwey transition. - Highlights: • Synthesis of monodispersed FeO nanoparticles is shown. • As-made FeO nanoparticle is antiferromagnetically ordered, when it is oxidized to Fe 3 O 4 , the FeO core becomes small and disordered. • Exchange bias in well-ordered and disordered core is different.

  8. Room temperature exchange bias in multiferroic BiFeO3 nano- and microcrystals with antiferromagnetic core and two-dimensional diluted antiferromagnetic shell

    Science.gov (United States)

    Zhang, Chuang; Wang, Shou Yu; Liu, Wei Fang; Xu, Xun Ling; Li, Xiu; Zhang, Hong; Gao, Ju; Li, De Jun

    2017-05-01

    Exchange bias (EB) of multiferroics presents many potential opportunities for magnetic devices. However, instead of using low-temperature field cooling in the hysteresis loop measurement, which usually shows an effective approach to obtain obvious EB phenomenon, there are few room temperature EB. In this article, extensive studies on room temperature EB without field cooling were observed in BiFeO3 nano- and microcrystals. Moreover, with increasing size the hysteresis loops shift from horizontal negative exchange bias (NEB) to positive exchange bias (PEB). In order to explain the tunable EB behaviors with size dependence, a phenomenological qualitative model based on the framework of antiferromagnetic (AFM) core-two-dimensional diluted antiferromagnet in a field (2D-DAFF) shell structure was proposed. The training effect (TE) ascertained the validity of model and the presence of unstable magnetic structure using Binek's model. Experimental results show that the tunable EB effect can be explained by the competition of ferromagnetic (FM) exchange coupling and AFM exchange coupling interaction between AFM core and 2D-DAFF shell. Additionally, the local distortion of lattice fringes was observed in hexagonal-shaped BiFeO3 nanocrystals with well-dispersed behavior. The electrical conduction properties agreed well with the space charge-limited conduction mechanism.

  9. Doping dependent magnetism and exchange bias in CaMn{sub 1−x}W{sub x}O{sub 3} manganites

    Energy Technology Data Exchange (ETDEWEB)

    Markovich, V., E-mail: markoviv@bgu.ac.il; Gorodetsky, G. [Department of Physics, Ben-Gurion University of the Negev, 84105 Beer-Sheva (Israel); Fita, I. [Institute of Physics, Polish Academy of Sciences, Aleja Lotnikow 32/46, PL-02-668 Warsaw (Poland); Donetsk Institute for Physics and Technology, National Academy of Sciences, 83114 Donetsk (Ukraine); Wisniewski, A.; Puzniak, R. [Institute of Physics, Polish Academy of Sciences, Aleja Lotnikow 32/46, PL-02-668 Warsaw (Poland); Mogilyansky, D. [The Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel); Naumov, S. V.; Mostovshchikova, E. V.; Telegin, S. V. [Institute of Metal Physics, Ural Branch of RAS, Kovalevskaya Street 18, Ekaterinburg 620990 (Russian Federation); Jung, G. [Department of Physics, Ben-Gurion University of the Negev, 84105 Beer-Sheva (Israel); Institute of Physics, Polish Academy of Sciences, Aleja Lotnikow 32/46, PL-02-668 Warsaw (Poland)

    2014-09-07

    Magnetic properties of CaMn{sub 1−x}W{sub x}O{sub 3} (0 ≤ x ≤ 0.1) have been investigated, and the research was focused on the exchange bias (EB) phenomenon in CaMn{sub 0.93}W{sub 0.07}O{sub 3}. Magnetic ground state was found to be dependent on tungsten doping level and the following states were distinguished: (i) G-type antiferromagnetic (AFM) state with a weak ferromagnetic (FM) component at x = 0 and 0.04; (ii) mostly orbitally ordered C-type AFM at x = 0.07 and 0.1. For the studied manganites, spontaneous magnetization increases sharply with increasing doping level reaching M{sub 0} ≈ 9.5 emu/g at T = 10 K for x = 0.04, and then decreases rapidly reaching zero for x = 0.1. Exchange bias effect, manifested by vertical and horizontal shifts in the hysteresis loop for field cooled sample, has been observed in CaMn{sub 0.93}W{sub 0.07}O{sub 3}. Exchange bias field, coercivity, remanence asymmetry, and magnetic coercivity depend strongly on temperature, cooling field, and maximal measuring field. Horizontal and vertical shifts of magnetization loop sharply decrease with increasing temperature and vanish above 70 K, whereas coercivity and magnetic coercivity disappear only above 100 K (temperature of transition to the G-type AFM state). The exchange bias field H{sub EB} increases with increasing cooling field H{sub cool} and goes through a broad maximum at 40 kOe, while the remanence asymmetry increases monotonously in the entire investigated cooling field range, up to 50 kOe. For the compound with x = 0.07, the size of the FM regions ≈2 nm was estimated from the dependence of exchange bias field H{sub EB} upon H{sub cool}. It is suggested that the exchange bias originates from interface exchange coupling between small FM clusters and the G-type AFM phase inside the primary C-type orbitally ordered AFM phase.

  10. Tunable exchange bias effect in magnetic Bi0.9Gd0.1Fe0.9Ti0.1O3 nanoparticles at temperatures up to 250K

    DEFF Research Database (Denmark)

    Basith, M. A.; Khan, F. A.; Ahmmad, Bashir

    2015-01-01

    that the strength of the exchange bias effect is tunable by the field cooling. The HEB values are also found to be dependent on the temperature. This magnetically tunable exchange bias obtained at temperatures up to 250K in Bi0.9Gd0.1Fe0.9Ti0.1O3 nanoparticles may be worthwhile for potential applications.......The exchange bias (EB) effect has been observed in magnetic Bi0.9Gd0.1Fe0.9Ti0.1O3 nanoparticles.The influence of magnetic field cooling on the exchange bias effect has also been investigated. The magnitude of the exchange bias field (HEB) increases with the cooling magnetic field, showing...

  11. History of establishment of scientific technology law focused on exchanges of Korea, China and Japan

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Gyeong Hui

    1990-10-15

    This book introduces science and technology promotion related law, industrial technology related law, resources and energy related law, nuclear energy related law, information and communication related law, intellectual property right related law, and environment related law. It explains process of development of 7 laws in threes countries and relations of three countries exchanges. It also covers special law for science and technology innovation, electric utility law, petroleum enterprise law, telecommunication related law, law of settlement of digital divide, and information-oriented law.

  12. History of establishment of scientific technology law focused on exchanges of Korea, China and Japan

    International Nuclear Information System (INIS)

    Lee, Gyeong Hui

    1990-10-01

    This book introduces science and technology promotion related law, industrial technology related law, resources and energy related law, nuclear energy related law, information and communication related law, intellectual property right related law, and environment related law. It explains process of development of 7 laws in threes countries and relations of three countries exchanges. It also covers special law for science and technology innovation, electric utility law, petroleum enterprise law, telecommunication related law, law of settlement of digital divide, and information-oriented law.

  13. Negative magnetization and the tunable exchange bias field in LaCr{sub 0.8}Mn{sub 0.2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Bora, Tribedi; Ravi, S., E-mail: sravi@iitg.ernet.in

    2014-05-01

    Manganese substituted Lanthanum chromite LaCr{sub 0.8}Mn{sub 0.2}O{sub 3} exhibits negative magnetization with decrease in temperature under the field cooled (FC) condition for the applied field H≤2000 Oe. The maximum magnetic compensation temperature, (T{sub comp}) was 147 K. A reentrant positive magnetization was observed at T≤50 K due to low temperature transition. The negative magnetization is explained by considering the paramagnetic moment of Mn ions under the influence of negative internal field. Measurement of magnetic hysteresis loops under FC condition shows the presence of exchange bias field at Texchange bias phenomenon at Texchange bias field is found to increase with decrease in cooling field. The origin of exchange bias field is explained in terms of anisotropic exchange interaction between the canted ferromagnetic component of Cr{sup 3+} ions and the paramagnetic component of Mn{sup 3+} ions under the negative internal field.

  14. Spin structure of exchange biased heterostructures. Fe/MnF{sub 2} and Fe/FeF{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Sahoo, B.

    2006-12-18

    In this work, the {sup 57}Fe probe layer technique is used in order to investigate the depth- and temperature-dependent Fe-layer spin structure of exchange biased Fe/MnF{sub 2} and Fe/FeF{sub 2} (pseudo-twinned) antiferromagnetic (AFM) systems by conversion electron Moessbauer spectroscopy (CEMS) and nuclear resonant scattering (NRS) of synchrotron radiation. Two kinds of samples with a 10 A {sup 57}Fe probe layer directly at or 35 A away from the interface, labeled as interface and center sample, respectively, were studied in this work. The results obtained by CEMS for Fe/MnF{sub 2} suggests that, at 80 K, i.e., above T{sub N}=67 K of MnF{sub 2}, the remanent state Fe-layer spin structure of the two studied samples are slightly different due to their different microstructure. In the temperature range from 300 K to 80 K, the Fe-layer spin structure does not change just by zero-field cooling the sample in remanence. For Fe/FeF{sub 2}, a continuous non-monotonic change of the remanent-state Fe spin structure was observed by cooling from 300 K to 18 K. NRS of synchrotron radiation was used to investigate the temperature- and depth-dependent Fe-layer spin structure during magnetization reversal in pseudo-twinned Fe/MnF{sub 2}. A depthdependent Fe spin structure in an applied magnetic field (applied along the bisector of the twin domains) was observed at 10 K, where the Fe spins closer to the interface are not aligned along the field direction. The depth-dependence disappears at 150 K. (orig.)

  15. Magnetic stability under magnetic cycling of MgO-based magnetic tunneling junctions with an exchange-biased synthetic antiferromagnetic pinned layer

    Directory of Open Access Journals (Sweden)

    Qiang Hao

    2016-02-01

    Full Text Available We investigate the magnetic stability and endurance of MgO-based magnetic tunnel junctions (MTJs with an exchange-biased synthetic antiferromagnetic (SAF pinned layer. When a uniaxially cycling switching field is applied along the easy axis of the free magnetic layer, the magnetoresistance varies only by 1.7% logarithmically with the number of cycles, while no such change appears in the case of a rotating field. This observation is consistent with the effect of the formation and motion of domain walls in the free layer, which create significant stray fields within the pinned hard layer. Unlike in previous studies, the decay we observed only occurs during the first few starting cycles (<20, at which point there is no further variance in all performance parameters up to 107 cycles. Exchange-biased SAF structure is ideally suited for solid-state magnetic sensors and magnetic memory devices.

  16. Influence of time dependent longitudinal magnetic fields on the cooling process, exchange bias and magnetization reversal mechanism in FM core/AFM shell nanoparticles: a Monte Carlo study.

    Science.gov (United States)

    Yüksel, Yusuf; Akıncı, Ümit

    2016-12-07

    Using Monte Carlo simulations, we have investigated the dynamic phase transition properties of magnetic nanoparticles with ferromagnetic core coated by an antiferromagnetic shell structure. Effects of field amplitude and frequency on the thermal dependence of magnetizations, magnetization reversal mechanisms during hysteresis cycles, as well as on the exchange bias and coercive fields have been examined, and the feasibility of applying dynamic magnetic fields on the particle have been discussed for technological and biomedical purposes.

  17. Asymmetry of nucleation density and its variation with Pt spacer thickness in exchange-biased [Pt/Co]5/Pt/FeMn multilayers

    Science.gov (United States)

    Fassatoui, Aymen; Belhi, Rachid; Vogel, Jan; Pizzini, Stefania; David, Philippe; Abdelmoula, Kahena

    2018-03-01

    The magnetization reversal of perpendicular exchange-biased [Pt/Co]5/Pt/FeMn multilayers was investigated by magneto-optical Kerr microscopy. The effect of varying the Pt interlayer thickness between the topmost Co layer and the FeMn layer was studied. Our measurements reveal that coercivity (HC) and exchange bias field (HEB) vary with Pt spacer thickness, and have a maximum for a Pt thickness of 0.4 nm. Magnetization reversal measurements show that, for the unbiased multilayer, the reversal is dominated by domain wall propagation starting from a few nucleation centers. For the exchange-biased multilayers, magnetization reversal occurs by nucleation and domain wall propagation with a variation in the nucleation density. For 0 and 0.2 nm Pt spacer, no difference is observed in the nucleation density of the ascending and descending branches unlike for 0.4 and 0.6 nm Pt spacer where the measurements reveal a larger density of nucleation centers in the descending branch.

  18. Magnetization reversal and tunable exchange bias in GdCr{sub 1−x}Mn{sub x}O{sub 3} (x=0−0.50)

    Energy Technology Data Exchange (ETDEWEB)

    Dash, Bibhuti B.; Ravi, S., E-mail: sravi@iitg.ernet.in

    2017-05-01

    Single phase samples of GdCr{sub 1-x}Mn{sub x}O{sub 3} (x=0−0.50) were prepared and their magnetic properties were studied by measuring temperature and field variations of magnetization. The Neel temperature, T{sub N} is found to decrease from T{sub N}=174 K for x=0 to 91 K for x=0.50. The magnetization reversal persists upto 5 at% of Mn substitution with a magnetic compensation temperature, T{sub comp} of 136 K and 139 K for x=0 and 0.05 respectively. However, spin reorientation induced magnetization reversal emerges for x=0.40 and 0.50 samples around 30 K. Tunable positive and negative exchange bias fields in the range of −1.0 kOe to +1.6 kOe have been observed. The origin of magnetization reversal and exchange bias field is explained in terms of antiparallel alignment of canted ferromagnetic component of Cr{sup 3+} ions and the paramagnetic moments of Gd{sup 3+} and Mn{sup 3+} ions under the influence of negative internal field due to antiferromagnetically ordered Cr{sup 3+} ions. - Highlights: • Magnetization reversal and bipolar switching in Mn substituted GdCrO{sub 3} • Tunable exchange bias field in the range of −1.0 kOe to +1.6 kOe. • Low temperature spin reorientation transition is observed.

  19. Antisite-disorder driven large exchange bias effect in phase separated La_1_._5Ca_0_._5CoMnO_6 double perovskite

    International Nuclear Information System (INIS)

    Sahoo, R.C.; Paladhi, D.; Dasgupta, Papri; Poddar, A.; Singh, Ripandeep; Das, A.; Nath, T.K.

    2017-01-01

    Investigations of structural and magnetic properties of polycrystalline hole doped double perovskite La_1_._5Ca_0_._5CoMnO_6 has clearly revealed the existence of structural antisite-disorder (either, Co–O–Co or Mn–O–Mn) in the system. The ordering of Co"2"+ and Mn"4"+ gives rise to a ferromagnetic transition around 157 K. A spin-canted antiferromagnetic transition is found in this material at T_C_A_F_M ~9 K. The effect of antisite-disorder in the double perovskite structure is most likely the prime reason for antiferromagnetic interaction. The temperature dependent inverse susceptibility exhibits Curie-Weiss like behaviour and it yields an effective paramagnetic moment of 6.49 μ_B. At very low temperature (T< T_C_A_F_M), it shows a strong hysteresis loop shift with large exchange bias (EB) field of H_E_B ~5.5 kOe and can be tuned by the cooling field. The presence of zero-field cooled spontaneous EB effect (P-type and N-type) is confirmed to be not an experimental artefact - an inherent property of this double perovskite material. A phenomenological model has been proposed to explain the exchange coupling between the ferromagnetic and canted-antiferromagnetic interfaces of antisite-disordered La_1_._5Ca_0_._5CoMnO_6 mainly on the basis of uncompensated interface spins. - Highlights: • Large exchange bias (EB) effect has been observed in 25% Ca doped La_2CoMnO_6 antisite-disordered system. • Neutron powder diffraction analysis clearly suggested canted antiferromagnetic spin ordering at low temperature in our phase separated system. • A phenomenological model has been proposed for experimental results. • The results may be useful to acquire enough information about exchange biased interfaces for various magnetic device applications.

  20. Monitoring of lateral hyporheic exchange fluxes and hyporheic travel times at the newly established Steinlach Test Site, Germany

    Science.gov (United States)

    Osenbrück, K.; Lemke, D.; Schwientek, M.; Callisto Alvarez, M. C.; Wöhling, Th.; Cirpka, O. A.

    2012-04-01

    Hyporheic exchange is believed to significantly contribute to the retention and degradation of pollutants during downstream transport in surface waters. A better understanding of the relevant hydraulic drivers of stream water infiltration into the hyporheic zone in conjunction with the associated biogeochemical processes is needed in order to quantify the self-cleaning potential of rivers and to predict water quality changes. Key parameters include the spatial and temporal variation of stream water infiltration (i.e. hyporheic exchange) and the distribution of hyporheic travel times. In this study we present the setup, performance and first results of a multi-disciplinary hyporheic monitoring program at the newly established Steinlach Test Site (STS) near Tübingen in Southern Germany. The STS covers an area of about 0.6 ha and consists of a river loop located within a sub-catchment of the Neckar river. The main objective is the quantification and interrelation of hyporheic processes including hyporheic exchange, travel-time distributions, microbial community dynamics and biochemical pollutant turnover at the groundwater-surface water interface. Here we will focus on the extent and time scale of hyporheic exchange fluxes at the STS derived from time series of temperature (T), specific electrical conductivity (EC), and δ18O of water. The STS is equipped with more than 30 piezometers, most of them containing automatic water level, T and EC probes. Additional water samples for major ions, stable isotopes and other water quality parameters were taken in the course of flood events in summer 2011. The sand and gravel aquifer in the subsurface of the STS is characterised by a complex geometry with heterogeneous hydraulic conductivity. Low residence times in the southern part are confirmed by a small to negligible response in EC and T at the respective piezometers compared to the large variation of EC in the stream water. Using deconvolution techniques, a mean travel time

  1. Subjective bias in PRA - the role of judgement in the selection of plant modeling input data for establishing safety goals

    International Nuclear Information System (INIS)

    Haenni, H.P.; Smith, A.L.

    1986-01-01

    The sources of the uncertainties are generally accepted as modeling deficiencies, lack of completeness in the analysis and the input data deficiencies. The role of judgement in selecting input data for establishing safety goals will be discussed. As an example, a safety goal for unacceptable radioactivity release will be considered. Two analysts are discussing the introduction of an emergency service water system, applying a different way of engineering judgement. Using PRA combined with safety goals as a decision-making tool it could have an important influence on the design and the costs of the plant. The suitability of the methodology has to be generally accepted before it will be established as a regulatory requirement. (orig.)

  2. Magnetic charge distribution and stray field landscape of asymmetric néel walls in a magnetically patterned exchange bias layer system

    Science.gov (United States)

    Zingsem, Norbert; Ahrend, Florian; Vock, Silvia; Gottlob, Daniel; Krug, Ingo; Doganay, Hatice; Holzinger, Dennis; Neu, Volker; Ehresmann, Arno

    2017-12-01

    The 3D stray field landscape above an exchange bias layer system with engineered domain walls has been fully characterized by quantitative magnetic force microscopy (qMFM) measurements. This method is based on a complete quantification of the MFM tip’s imaging properties and the subtraction of its contribution from the measured MFM data by deconvolution in Fourier space. The magnetically patterned Ir17Mn83/Co70Fe30-exchange-bias-multilayers have been designed to contain asymmetric head-to-head (hh)/tail-to-tail (tt) Néel walls between domains of different magnetic anisotropies for potential use in guided particle transport. In the current application, qMFM reveals the effective magnetic charge profile on the surface of the sample—with high spatial resolution and in an absolute quantitative manner. These data enable to calculate the magnetostatic potential and the full stray field landscape above the sample surface. It has been successfully tested against: (i) micromagnetic simulations of the magnetization structure of a comparable exchange-bias layer system, (ii) measurements of the magnetization profile across the domain boundary with x-ray photoemission electron microscopy, and (iii) direct stray field measurements obtained by scanning Hall probe microscopy at elevated scan heights. This approach results in a quantitative determination of the stray field landscape at close distances to the sample surface, which will be of importance for remote magnetic particle transport applications in lab-on-a-chip devices. Furthermore, the highly resolving and quantitative MFM approach reveals details of the domain transition across the artificially structured phase boundary, which have to be attributed to a continuous change in the materials parameters across this boundary, rather than an abrupt one.

  3. Exchange bias in sputtered FeNi/FeMn systems: Effect of short low-temperature heat treatments

    Energy Technology Data Exchange (ETDEWEB)

    Savin, Peter, E-mail: peter.savin@urfu.ru [Department of Magnetism and Magnetic Nanomaterials, Laboratory of Magnetic Sensors, Ural Federal University, 620002 Ekaterinburg (Russian Federation); Guzmán, Jorge [Instituto de Ciencia de Materiales de Madrid-CSIC, 28049 Madrid (Spain); Lepalovskij, Vladimir [Department of Magnetism and Magnetic Nanomaterials, Laboratory of Magnetic Sensors, Ural Federal University, 620002 Ekaterinburg (Russian Federation); Svalov, Andrey; Kurlyandskaya, Galina [Department of Magnetism and Magnetic Nanomaterials, Laboratory of Magnetic Sensors, Ural Federal University, 620002 Ekaterinburg (Russian Federation); Departamento de Electricidad y Electrónica, Universidad del País Vasco (UPV/EHU), 48940 Leioa, Vizcaya (Spain); Asenjo, Agustina [Instituto de Ciencia de Materiales de Madrid-CSIC, 28049 Madrid (Spain); Vas’kovskiy, Vladimir [Department of Magnetism and Magnetic Nanomaterials, Laboratory of Magnetic Sensors, Ural Federal University, 620002 Ekaterinburg (Russian Federation); Vazquez, Manuel [Department of Magnetism and Magnetic Nanomaterials, Laboratory of Magnetic Sensors, Ural Federal University, 620002 Ekaterinburg (Russian Federation); Instituto de Ciencia de Materiales de Madrid-CSIC, 28049 Madrid (Spain)

    2016-03-15

    Short (5 min) post-deposition thermal treatments under magnetic field at low temperature (up to 200 °C) performed in exchange-coupled FeNi(40 nm)/FeMn(20 nm) bilayer thin films prepared by magnetron sputtering are shown to be effective to significantly modify their exchange field (from around 40 Oe down to 27 Oe) between FeNi and FeMn layers. A similar exchange field decrease was observed for the first deposited FeNi layer of the FeNi(40 nm)/FeMn(20 nm)/FeNi(40 nm) trilayer films after the same thermal treatments. The exchange field value for the second FeNi layer was not substantially changed. The X-ray diffraction patterns indicates that such a heat treatment has no effect on the grain size and crystalline texture of the films, while atomic force microscope studies reveal an increase of the surface roughness after the treatment which is more noticeable in the case of the trilayer film. Analysis of the experimental results leads us to conclude that the variations of the exchange field after heat treatment are likely caused by a modification of interfacial roughness and/or interfacial magnetic structure, but unlikely by the changes in the microstructure and/or changes of composition of the antiferromagnetic FeMn layer. - Highlights: • FeNi/FeMn bilayers and FeNi/FeMn/FeNi trilayers were prepared by magnetron sputtering. • Post-deposition heat treatments at the temperatures below 200 °C during 5 min were made. • Annealing reduces the exchange field for the first FeNi layer in trilayers. • The exchange field value for the second FeNi layer was not substantially changed. • Exchange field changes are most likely caused by a modification of interface roughness.

  4. Electron holography study of remanence states in exchange-biased MnPd/Fe bilayers grown epitaxially on MgO(001).

    Science.gov (United States)

    Jeong, Jong Seok; Akase, Zentaro; Shindo, Daisuke; Zhan, Qing-Feng; Krishnan, Kannan M

    2011-01-01

    We investigated magnetic remanence states of epitaxially grown, exchange-biased MnPd/Fe bilayers by electron holography emphasizing the crystallographic orientations of the layers. Thin-foil transmission electron microscopy (TEM) specimens were carefully prepared along both hard and easy axes of the Fe layer. The ex situ magnetization-reversal process was carried out using the TEM specimens, and magnetic flux densities of the ultra-thin Fe layers were evaluated at different remanence states. We show that a spin configuration in the TEM specimens is determined by the competition between an exchange coupling at the MnPd/Fe bilayer interface, shape anisotropy of TEM specimens and intrinsic magnetocrystalline anisotropy of Fe.

  5. Bias in the exchange of arguments: The case of scientists' evaluation of lay viewpoints on GM food

    NARCIS (Netherlands)

    Cuppen, E.H.W.J.; Hisschemoller, M.; Midden, C.

    2009-01-01

    Most perspectives on public participation share the notion that dialogues should be open, allowing participants to articulate and evaluate different views and knowledge claims. We hypothesize that participants' evaluation of claims may be biased because participants have a preference for a

  6. Sign reversal of magnetization and tunable exchange bias field in NdCr{sub 1−x}Fe{sub x}O{sub 3} (x=0.05–0.2)

    Energy Technology Data Exchange (ETDEWEB)

    Bora, Tribedi; Ravi, S., E-mail: sravi@iitg.ernet.in

    2015-07-15

    Magnetization reversal and tunable exchange bias behavior are observed in NdCr{sub 1−x}Fe{sub x}O{sub 3} compounds for x=0.05–0.20. The magnetic compensation temperature (T{sub comp}) is found to increase with increase in Fe concentration and its maximum value is 198 K for x=0.15 sample. The observed magnetization reversal is explained by considering the competition between the weak ferromagnetic component of Cr{sup 3+} ions and the paramagnetic moments of Nd{sup 3+} and Fe{sup 3+} ions under the influence of negative internal magnetic field. The exchange anisotropy between the above two components of magnetic moments give rise to tunable positive and negative exchange bias fields. The sign reversal of exchange bias field also coincides with T{sub comp}. Bipolar switching of magnetization is demonstrated at Texchange bias in Nd(Cr,Fe)O system. • Paramagnetic and canted ferromagnetic moments give rise to magnetization reversal. • Mechanism of tunable positive and negative exchange bias fields is discussed.

  7. Amorphous FeCoSiB for exchange bias coupled and decoupled magnetoelectric multilayer systems: Real-structure and magnetic properties

    International Nuclear Information System (INIS)

    Hrkac, V.; Strobel, J.; Kienle, L.; Lage, E.; Köppel, G.; McCord, J.; Quandt, E.; Meyners, D.

    2014-01-01

    The effect of field annealing for exchanged biased multilayer films is studied with respect to the resultant structural and magnetic film properties. The presented multilayer stacks comprise repeating sequences of Ta/Cu/(1 1 1) textured antiferromagnetic Mn 70 Ir 30 /amorphous ferromagnetic Fe 70.2 Co 7.8 Si 12 B 10 . Within the ferromagnetic layers crystalline filaments are observed. An additional Ta layer between the antiferromagnet and ferromagnet is used in order to investigate and separate the influence of the common Mn 70 Ir 30 /Fe 70.2 Co 7.8 Si 12 B 10 interface on the occurring filaments and structural changes. In situ and ex situ transmission electron microscopy is used for a comprehensive structure characterization of multilayer stacks for selected temperature stages. Up to 250 °C, the multilayers are structurally unaltered and preserve the as-deposited condition. A deliberate increase to 350 °C exhibits different crystallization processes for the films, depending on the presence of crystal nuclei within the amorphous ferromagnetic layer. The influence of volume-to-surface ratio of the multilayer stacks to the crystallization process is emphasized by the comparison of in situ and ex situ investigations as the respective specimen thickness is changed. Complementary magnetic studies reveal a defined exchange bias obtained at the first annealing step and a decrease of total anisotropy field with partial crystallization after the subsequent annealing at 350 °C.

  8. Bias in the exchange of arguments: the case of scientists' evaluation of lay viewpoints on GM food.

    Science.gov (United States)

    Cuppen, Eefje; Hisschemøller, Matthijs; Midden, Cees

    2009-09-01

    Most perspectives on public participation share the notion that dialogues should be open, allowing participants to articulate and evaluate different views and knowledge claims. We hypothesize that participants' evaluation of claims may be biased because participants have a preference for a particular type or source of a claim. This would hamper an open dialogue. We tested the effect of three variables on scientists' evaluation of claims of the general public about GM food: the claim's favorability towards GM food, the phrasing, and the source of the claim. Results are based on a survey-experiment among 73 biotechnology-scientists. Biased processing occurred when scientists evaluated claims. Claims that were corresponding with the attitude of the scientists and that were phrased in a cognitive way were evaluated more positively than claims that were contrasting the attitude of the scientists and that were phrased in an affective way. Contrary to our expectation, scientists evaluated claims of the public more positively than claims of experts.

  9. Temperature dependence magnetic properties and exchange bias effect in CuFe{sub 2}O{sub 4} nanoparticles embedded in NiO matrix

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Kashif [Physics Department, Quaid-i-Azam University, Islamabad (Pakistan); Physics Department, International Islamic University, Islamabad (Pakistan); Physics Department, University of Gujrat, Gujrat (Pakistan); Sarfraz, A.K., E-mail: sarfraz.ak1@gmail.com [Physics Department, Quaid-i-Azam University, Islamabad (Pakistan); Physics Department, International Islamic University, Islamabad (Pakistan); Physics Department, University of Gujrat, Gujrat (Pakistan); Ali, Atif; Mumtaz, A.; Hasanain, S.K. [Physics Department, Quaid-i-Azam University, Islamabad (Pakistan); Physics Department, International Islamic University, Islamabad (Pakistan); Physics Department, University of Gujrat, Gujrat (Pakistan)

    2014-11-15

    The effect of temperature on the magnetic properties of CuFe{sub 2}O{sub 4}/NiO nanocomposites of (1−x) NiO/xCuFe{sub 2}O{sub 4} (x=0.5) has been investigated. The (1−x)NiO/xCuFe{sub 2}O{sub 4} (x=0.5) nanoparticles were synthesized by co-precipitation route and their crystallographic structure was confirmed through X-ray diffraction (XRD) analysis. The average crystallite sizes of the nanoparticles as determined from the XRD were found to lie in the range of 20–31 nm. Magnetic characterization including coercivity and magnetization were measured with effect of particle size and temperature. During magnetic measurement it is observed that the hysteresis loop displaces along negative field axis with exchange bias field (H{sub EB}) about 75 Oe at 5 K and vanish at 150 K which is irreversible temperature T{sub irr}. The temperature dependence of coercively follows Kneller's law while the saturation magnetization followed Bloch's law with exponent α=3/2. - Highlights: • Synthesis of (1−x)NiO/xCuFe{sub 2}O{sub 4} (x=0.5) nanoparticles by co-precipitation route. • Magnetic characterization with particle size and temperature variation. • Exchange bias effect: monotonic decrease in exchange field with temperature. • Temperature dependence of coercivity follows Kneller's law. • Temperature dependence of saturation magnetization follows Bloch's law.

  10. Study of angular dependence of exchange bias and misalignment in uniaxial and unidirectional anisotropy in NiFe(111)/FeMn(111)/CoFeB(amorphous) stack

    International Nuclear Information System (INIS)

    Singh, Braj Bhusan; Chaudhary, Sujeet

    2015-01-01

    We report the investigation of the in-plane azimuthal angular dependence of the magnetization reversal in the ion beam sputtered exchanged biased NiFe(111)/FeMn(111)/CoFeB(amorphous) stack. Compared to the as-deposited case, the magnetic annealing resulted in 3 fold enhancement in exchange bias but decrease in coercivity. The observed cosine dependence of exchange biased CoFeB layer on the in-plane azimuthal angle of applied field is corroborated with Meiklejohn and Bean model. The training effect associated with the exchange bias showed unconventional increase in coercivity after first cycle of hysteresis loop, while the exchange bias decreases sharply, and for subsequent cycles the exchange bias follows the empirical relation based on the energy dissipation in the AF layer. The ferromagnetic resonance (FMR) measurements also exhibited the in-plane azimuthal angle dependence of the magnetic resonance field indicating that the uniaxial and unidirectional anisotropies are not collinear, although they lie in the same plane. However, no misalignment between the unidirectional anisotropy and the exchange bias direction is observed. The misalignment angle between the uniaxial and unidirectional anisotropy, as measured by FMR, is found to be 10° and 14° for CoFeB and NiFe, respectively. This misalignment is attributed to the interface roughness as revealed by x-ray reflectance measurements. - Highlights: • In-plane azimuthal angular dependence of the magnetization reversal in the ion beam sputtered exchanged biased NiFe(111)/FeMn(111)/ CoFeB(amorphous) stack. • The observed cosine dependence of exchange biased CoFeB layer on the in-plane azimuthal angle of applied field is corroborated with Meiklejohn and Bean model. • In-plane azimuthal angle dependence of the magnetic resonance field indicates that the uniaxial and unidirectional anisotropies are not collinear, although they lie in the same plane. • The misalignment angle between the uniaxial and

  11. Oscillatory exchange bias effect in La0.67Sr0.33MnO3/G-SrMnO3/La0.67Sr0.33MnO3 sandwiches

    Science.gov (United States)

    Mao, H. J.; Li, F.; Xiao, L. R.; Wang, Y. Y.; Cui, B.; Peng, J. J.; Pan, F.; Song, C.

    2015-07-01

    We investigate the exchange bias effect in La0.67Sr0.33MnO3/G-SrMnO3/ La0.67Sr0.33MnO3 (LSMO/SMO/LSMO) sandwiches, where the spacer is a G-type antiferromagnet. Because of the cycloid bulk spins in the SMO modulated by the top LSMO layer, the sandwich structure exhibits an oscillatory exchange bias behavior as a function of the SMO thickness. This unprecedented phenomenon vanishes in LSMO/SMO bilayers, where the exchange bias saturates as the SMO thickness increases, giving rise to the antiferromagnetic anisotropy constant of SMO, 1.0 -2.0   ×   105 erg cm-3. The results provide a broad opportunity to tailor antiferromagnetic moments by interfacial design for antiferromagnet spintronics.

  12. Magnetic properties of NiMn{sub 2}O{sub 4−δ} (nickel manganite): Multiple magnetic phase transitions and exchange bias effect

    Energy Technology Data Exchange (ETDEWEB)

    Tadic, Marin, E-mail: marint@vinca.rs [Condensed Matter Physics Laboratory, Vinca Institute of Nuclear Sciences, University of Belgrade, POB 522, 11001 Belgrade (Serbia); Savic, S.M. [Institute for Multidisciplinary Research, University of Belgrade, Kneza Viseslava 1, 11000 Belgrade (Serbia); Jaglicic, Z. [University of Ljubljana, Faculty of Civil Engineering and Geodesy and Institute of Mathematics, Physics and Mechanics, Jadranska 19, 1000 Ljubljana (Slovenia); Vojisavljevic, K.; Radojkovic, A.; Prsic, S. [Institute for Multidisciplinary Research, University of Belgrade, Kneza Viseslava 1, 11000 Belgrade (Serbia); Nikolic, Dobrica [Department of Physics, University of Belgrade Faculty of Mining and Geology, Belgrade (Serbia)

    2014-03-05

    Highlights: • We have successfully synthesized NiMn{sub 2}O{sub 4−δ} sample by complex polymerization synthesis. • Magnetic measurements reveal complex properties and triple magnetic phase transitions. • Magnetic measurements of M(H) show hysteretic behavior below 120 K. • Hysteresis properties after cooling of the sample in magnetic field show exchange bias effect. -- Abstract: We present magnetic properties of NiMn{sub 2}O{sub 4−δ} (nickel manganite) which was synthesized by complex polymerization synthesis method followed by successive heat treatment and final calcinations in air at 1200 °C. The sample was characterized by using X-ray powder diffractometer (XRPD), scanning electron microscopy (SEM), field-emission scanning electron microscopy (FE-SEM) and superconducting quantum interference device (SQUID) magnetometer. The XRPD and FE-SEM studies revealed NiMn{sub 2}O{sub 4−δ} phase and good crystallinity of particles. No other impurities have been observed by XRPD. The magnetic properties of the sample have been studied by measuring the temperature and field dependence of magnetization. Magnetic measurements of M(T) reveal rather complex magnetic properties and multiple magnetic phase transitions. We show three magnetic phase transitions with transition temperatures at T{sub M1} = 35 K (long-range antiferromagnetic transition), T{sub M2} = 101 K (antiferromagnetic-type transition) and T{sub M3} = 120 K (ferromagnetic-like transition). We found that the T{sub M1} transition is strongly dependent on the strength of the applied magnetic field (T{sub M1} decreases with increasing applied field) whereas the T{sub M3} is field independent. Otherwise, the T{sub M2} maximum almost disappears in higher applied magnetic fields (H = 1 kOe and 10 kOe). Magnetic measurements of M(H) show hysteretic behavior below T{sub M3}. Moreover, hysteresis properties measured after cooling of the sample in magnetic field of 10 kOe show exchange bias effect with an

  13. Reconciling a "pleasant exchange" with evidence of information bias: A three-country study on pharmaceutical sales visits in primary care.

    Science.gov (United States)

    Reynolds, Ellen; Guénette, Line; Lexchin, Joel; Cassels, Alan; Wilkes, Michael S; Durrieu, Geneviève; Beaulieu, Marie-Dominique; Mintzes, Barbara

    2018-03-01

    To examine and compare the experiences and attitudes of primary care physicians in three different regulatory environments (United States, Canada, and France) towards interactions with pharmaceutical sales representatives, particularly their perspectives on safety information provision and self-reported influences on prescribing. We recruited primary care physicians for 12 focus groups in Montreal, Sacramento, Toulouse and Vancouver. A thematic analysis of the interview data followed a five-stage framework analysis approach. Fifty-seven family physicians (19 women, 38 men) participated. Physicians expected a commercial bias and generally considered themselves to be immune from influence. They also appreciated the exchange and the information on new drugs. Across all sites, physicians expressed concern about missing harm information; however, attitudes to increased regulation of sales visits in France and the US were generally negative. A common solution to inadequate harm information was to seek further commercially sourced information. Physicians at all sites also expressed sensitivity to critiques from medical students and residents about promotional interactions. Physicians have contradictory views on the inadequate harm information received from sales representatives, linked to their lack of awareness of the drugs' safety profiles. Commonly used strategies to mitigate information bias are unlikely to be effective. Alternate information sources to inform prescribing decisions, and changes in the way that physicians and sales representatives interact are needed. Copyright © 2018 Elsevier B.V. All rights reserved.

  14. Exchange bias and strain effect co-modulated magnetic symmetry in La0.6Sr0.4MnO3/orthorhombic-YMnO3 multiferroic heterostructures

    KAUST Repository

    Zheng, Dongxing

    2017-05-03

    The exchange bias and strain effect co-modulated magnetic symmetry in all oxide La0.6Sr0.4MnO3 (LSMO) and orthorhombic YMnO3 (YMO) multiferroic heterostructures were studied. Because of the lattice mismatch between the LSMO and YMO layers, the LSMO layer exhibits a 90° rotation growth on the YMO layer. The strain induced growth not only leads to a 90° phase shift in the anisotropic magnetoresistance (AMR) curves, but also brings a two-fold symmetric magnetoelastic coupling energy along the LSMO $[1\\\\,1\\\\,0]$ direction. With the incorporation of magnetoelastic coupling energy and exchange coupling energy, the exchange bias induced torque shows a phase shift and causes the asymmetry of the peak position and value in the AMR curves. This work illustrates a modulated magnetic symmetry in ferromagnetic/multiferroic systems by interfacial exchange coupling and strain effect, which will benefit the design of magnetoelectric devices.

  15. Exchange bias and strain effect co-modulated magnetic symmetry in La0.6Sr0.4MnO3/orthorhombic-YMnO3 multiferroic heterostructures

    Science.gov (United States)

    Zheng, Dongxing; Gong, Junlu; Jin, Chao; Li, Peng; Feng, Liefeng; Bai, Haili

    2017-06-01

    The exchange bias and strain effect co-modulated magnetic symmetry in all oxide La0.6Sr0.4MnO3 (LSMO) and orthorhombic YMnO3 (YMO) multiferroic heterostructures were studied. Because of the lattice mismatch between the LSMO and YMO layers, the LSMO layer exhibits a 90° rotation growth on the YMO layer. The strain induced growth not only leads to a 90° phase shift in the anisotropic magnetoresistance (AMR) curves, but also brings a two-fold symmetric magnetoelastic coupling energy along the LSMO [1 1 0] direction. With the incorporation of magnetoelastic coupling energy and exchange coupling energy, the exchange bias induced torque shows a phase shift and causes the asymmetry of the peak position and value in the AMR curves. This work illustrates a modulated magnetic symmetry in ferromagnetic/multiferroic systems by interfacial exchange coupling and strain effect, which will benefit the design of magnetoelectric devices.

  16. Training and recovery behaviors of exchange bias in FeNi/Cu/Co/FeMn spin valves at high field sweep rates

    Energy Technology Data Exchange (ETDEWEB)

    Yang, D.Z. [Institutt for fysikk, NTNU, NO-7491 Trondheim (Norway); Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education, Lanzhou University, Lanzhou 730000 (China); Kapelrud, A.; Saxegaard, M. [Institutt for fysikk, NTNU, NO-7491 Trondheim (Norway); Wahlstroem, E., E-mail: erik.wahlstrom@ntnu.no [Institutt for fysikk, NTNU, NO-7491 Trondheim (Norway)

    2012-09-15

    Training and recovery of exchange bias in FeNi/Cu/Co/FeMn spin valves have been studied by magnetoresistance curves with field sweep rates from 1000 to 4800 Oe/s. It is found that training and recovery of exchange field are proportional to the logarithm of the training cycles and recovery time, respectively. These behaviors are explained within the model based on thermal activation. For the field sweep rates of 1000, 2000 and 4000 Oe/s, the relaxation time of antiferromagnet spins are 61.4, 27.6, and 11.5 in the unit of ms, respectively, much shorter than the long relaxation time ({approx}10{sup 2}s) in conventional magnetometry measurements. - Highlights: Black-Right-Pointing-Pointer We measure antiferromagnet (AFM) spin dynamic behaviors at high field sweep rates. Black-Right-Pointing-Pointer Increasing the field sweep rates will reduce the AFM recovery and relaxation time. Black-Right-Pointing-Pointer AFM spin is in millisecond timescale, shorter the conventional report ({approx}10{sup 2}-10{sup 4}).

  17. Estimation of bias with the single-zone assumption in measurement of residential air exchange using the perfluorocarbon tracer gas method.

    Science.gov (United States)

    Van Ryswyk, K; Wallace, L; Fugler, D; MacNeill, M; Héroux, M È; Gibson, M D; Guernsey, J R; Kindzierski, W; Wheeler, A J

    2015-12-01

    Residential air exchange rates (AERs) are vital in understanding the temporal and spatial drivers of indoor air quality (IAQ). Several methods to quantify AERs have been used in IAQ research, often with the assumption that the home is a single, well-mixed air zone. Since 2005, Health Canada has conducted IAQ studies across Canada in which AERs were measured using the perfluorocarbon tracer (PFT) gas method. Emitters and detectors of a single PFT gas were placed on the main floor to estimate a single-zone AER (AER(1z)). In three of these studies, a second set of emitters and detectors were deployed in the basement or second floor in approximately 10% of homes for a two-zone AER estimate (AER(2z)). In total, 287 daily pairs of AER(2z) and AER(1z) estimates were made from 35 homes across three cities. In 87% of the cases, AER(2z) was higher than AER(1z). Overall, the AER(1z) estimates underestimated AER(2z) by approximately 16% (IQR: 5-32%). This underestimate occurred in all cities and seasons and varied in magnitude seasonally, between homes, and daily, indicating that when measuring residential air exchange using a single PFT gas, the assumption of a single well-mixed air zone very likely results in an under prediction of the AER. The results of this study suggest that the long-standing assumption that a home represents a single well-mixed air zone may result in a substantial negative bias in air exchange estimates. Indoor air quality professionals should take this finding into consideration when developing study designs or making decisions related to the recommendation and installation of residential ventilation systems. © 2014 Her Majesty the Queen in Right of Canada. Indoor Air published by John Wiley & Sons Ltd Reproduced with the permission of the Minister of Health Canada.

  18. Exchange bias effect in L10-ordered FePt and FeCo-based bilayer structure: effect of increasing applied field

    Science.gov (United States)

    Singh, Sadhana; Kumar, Dileep; Bhagat, Babli; Choudhary, R. J.; Reddy, V. R.; Gupta, Ajay

    2018-02-01

    The applied magnetic field (H APP) dependence of the exchange bias (EB) is studied in an exchange-coupled thin-film bilayer composed of a hard ferromagnetic FePt layer in the proximity of a soft ferromagnetic FeCo layer. FePt/FeCo structure is deposited in an ultra-high vacuum chamber, where the FePt layer was first annealed at 823 K for 30 min and subsequently cooled to room temperature in the presence of an in-plane magnetic field, H MAX ~ 1.5 kOe to promote L10-ordered hard magnetic phase with magnetic moments aligned in one of the in-plane directions in the FePt layer. In-situ magneto-optical Kerr effect measurements during different stages of bilayer growth and detailed ex-situ superconducting quantum interference device-vibrating sample magnetometer measurements jointly revealed that due to the interplay between exchange coupling at the interface and dipolar energies of the saturated hard FePt layer, a hysteresis loop of FeCo layer shifts along the magnetic field axis. A clear dependence of EB field (H EB) on increasing maximum value of the H APP during the hysteresis loop measurement is understood in terms of the magnetic state of soft and hard magnetic layers, where EB increases with increasing H APP until the hard layer moment remains undisturbed in its remanence state. As soon as the field was sufficient to rotate the spins of the FePt layer, the loop became symmetric with respect to the field axis.

  19. 41 CFR 301-72.300 - What procedures must we establish to collect unused, partially used, and exchanged tickets?

    Science.gov (United States)

    2010-07-01

    ... AGENCY RESPONSIBILITIES 72-AGENCY RESPONSIBILITIES RELATED TO COMMON CARRIER TRANSPORTATION Unused, Partially Used, Exchanged, Canceled, or Oversold Common Carrier Transportation Services § 301-72.300 What... administrative procedures providing: (a) Written instructions explaining traveler liability for the value of...

  20. Investigating Exchange Bias and Coercivity in Fe3O4–γ-Fe2O3 Core–Shell Nanoparticles of Fixed Core Diameter and Variable Shell Thicknesses

    Directory of Open Access Journals (Sweden)

    Ihab M. Obaidat

    2017-11-01

    Full Text Available We have carried out extensive measurements on novel Fe3O4–γ-Fe2O3 core–shell nanoparticles of nearly similar core diameter (8 nm and of various shell thicknesses of 1 nm (sample S1, 3 nm (sample S2, and 5 nm (sample S3. The structure and morphology of the samples were studied using X-ray diffraction (XRD, transmission electron microscopy (TEM, and selected area electron diffraction (SAED. The direct current (DC magnetic measurements were carried out using a superconducting quantum interference device (SQUID. Exchange bias and coercivity were investigated at several temperatures where the applied field was varied between 3 and −3 T. Several key results are obtained, such as: (a the complete absence of exchange bias effect in sample S3; (b the occurrence of nonconventional exchange bias effect in samples S2 and S1; (c the sign-change of exchange bias field in sample S2; (d the monotonic increase of coercivity with temperature above 100 K in all samples; (e the existence of a critical temperature (100 K at which the coercivity is minimum; (f the surprising suppression of coercivity upon field-cooling; and (g the observation of coercivity at all temperatures, even at 300 K. The results are discussed and attributed to the existence of spin glass clusters at the core–shell interface.

  1. Exchange bias in UO.sub.2./sub./Fe.sub.3./sub.O.sub.4./sub. thin films above the Néel temperature of UO.sub.2./sub

    Czech Academy of Sciences Publication Activity Database

    Tereshina, Evgeniya; Bao, Z.; Havela, L.; Daniš, S.; Kuebel, C.; Gouder, T.; Caciuffo, R.

    2014-01-01

    Roč. 105, č. 12 (2014), "122405-1"-"122405-5" ISSN 0003-6951 R&D Projects: GA ČR GP13-25866P Institutional support: RVO:68378271 Keywords : exchange bias effect * uranium dioxide * magnetite Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.302, year: 2014

  2. Positive and negative exchange bias effects from magnetization reversal in Ho{sup 3+} doped YFe{sub 0.5}Cr{sub 0.5}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Shi, L.R., E-mail: shiliran1127@126.com [College of Physics and Electrical Engineering, Anyang Normal University, Anyang 455000 (China); Wei, C.X.; Wang, Z.; Ju, L.; Xu, T.S.; Li, T.X.; Yan, X.W. [College of Physics and Electrical Engineering, Anyang Normal University, Anyang 455000 (China); Xia, Z.C. [Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2017-07-01

    Highlights: • The dual magnetization reversal is observed in Y{sub 1−x}Ho{sub x}Fe{sub 0.5}Cr{sub 0.5}O{sub 3}. • The EB field transforms from negative to positive and then to negative. • A large exchange bias effect induced by Ho{sup 3+} doping is obtained in Y{sub 1−x}Ho{sub x}Fe{sub 0.5}Cr{sub 0.5}O{sub 3}. - Abstract: The polycrystalline ceramics of Y{sub 1−x}Ho{sub x}Fe{sub 0.5}Cr{sub 0.5}O{sub 3} (x = 0, 0.05 and 0.1) are synthesized by a sol-gel method. The magnetization reversal and exchange bias effect are investigated in single phase bulk Y{sub 1−x}Ho{sub x}Fe{sub 0.5}Cr{sub 0.5}O{sub 3}. Magnetic Ho{sup 3+} ion as a dopant is introduced into the system to confirm the influence of A-site ion on the magnetic interactions. The dual reversal of exchange bias field for x = 0.05 is observed, and its characteristic temperatures are corresponding to the compensation temperatures of magnetization reversal. The exchange bias field of x = 0.1 is found to be ∼10.03 kOe at 4 K, revealing a large value compared with that of x = 0. A schematic diagram based on the competition between the single ion anisotropy and Dzyaloshinsky-Moriya interaction, and the antiparallel coupling between the Ho{sup 3+} moments and the canted Cr{sup 3+}/Fe{sup 3+} moments, is used to understand the dual reversal phenomenon of magnetization and exchange bias effect.

  3. Spin glass-like properties and exchange bias in La1.5Sr0.5CoIrO6

    Science.gov (United States)

    Coutrim, L. T.; Bittar, E. M.; Baggio-Saitovitch, E.; Bufaiçal, L.

    2017-11-01

    In this work we report the synthesis and investigation of magnetic properties of La1.5Sr0.5CoIrO6. Study of temperature dependent magnetization on this double-perovskite compound revealed two anomalies at T ≃ 88 K and T ≃ 68 K, probably related to antiferromagnetic and ferromagnetic couplings of Co and Ir ions, respectively. At T ≃ 27 K there is another anomaly, which was confirmed by means of ac magnetic susceptibility measurements to be related to the emergence of a spin glass(SG)-like phase. Magnetization as a function of applied magnetic field measurements revealed exchange bias effect of the same order of magnitude of that found for La1.5Ca0.5CoIrO6 analogue compound. We compare our results for La1.5Sr0.5CoIrO6 with those reported for La1.5Ca0.5CoIrO6, and discuss the magnetic properties of both materials in terms of their structural and electronic properties.

  4. Probing the ground state and zero-field cooled exchange bias by magnetoresistance measurement in Mn{sub 50}Ni{sub 41}Sn{sub 9} ribbon

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jiyun [Jiangsu Laboratory of Advanced Functional Materials, Department of Physics, Changshu Institute of Technology, Changshu 215500 (China); School of Materials Science and Engineering, China University of Mining & Technology, Xuzhou 221116 (China); Tu, Ruikang [Jiangsu Laboratory of Advanced Functional Materials, Department of Physics, Changshu Institute of Technology, Changshu 215500 (China); School of Materials Science and Engineering, Soochow University, Suzhou 215000 (China); Fang, Xiaoting [Jiangsu Laboratory of Advanced Functional Materials, Department of Physics, Changshu Institute of Technology, Changshu 215500 (China); Gu, Quanchao [Jiangsu Laboratory of Advanced Functional Materials, Department of Physics, Changshu Institute of Technology, Changshu 215500 (China); School of Materials Science and Engineering, Soochow University, Suzhou 215000 (China); Zhou, Yanying [Jiangsu Laboratory of Advanced Functional Materials, Department of Physics, Changshu Institute of Technology, Changshu 215500 (China); Cui, Rongjing [Department of Chemistry, Changshu Institute of Technology, Changshu 215500 (China); Han, Zhida, E-mail: han@cslg.edu.cn [Jiangsu Laboratory of Advanced Functional Materials, Department of Physics, Changshu Institute of Technology, Changshu 215500 (China); Zhang, Lei; Fang, Yong [Jiangsu Laboratory of Advanced Functional Materials, Department of Physics, Changshu Institute of Technology, Changshu 215500 (China); Qian, Bin, E-mail: njqb@cslg.edu.cn [Jiangsu Laboratory of Advanced Functional Materials, Department of Physics, Changshu Institute of Technology, Changshu 215500 (China); Zhang, Chengliang [School of Science, Jiangnan University, Wuxi 214122 (China); Jiang, Xuefan [Jiangsu Laboratory of Advanced Functional Materials, Department of Physics, Changshu Institute of Technology, Changshu 215500 (China)

    2017-03-15

    Recently, a new type of exchange bias (EB) after zero-field cooling has attracted considerable interest mainly in bulk magnetic competing systems. Here, we use a detailed magnetotransport investigation to probe the ground state and zero-field cooled EB (ZEB) in Mn{sub 50}Ni{sub 41}Sn{sub 9} ribbon. Both ZEB and field cooled EB were detected in magnetoresistance results consistent with magnetic measurement. A pure spin-glass ground state is proposed based on parabolic shape of low-field magnetoresistance combined with AC magnetization, memory effect. The appearance of ZEB is attributed to the field-induced nucleation and growth of ferromagnetic domains in the spin glass matrix forming unidirectional anisotropy at the interface. - Highlights: • Magnetoresistance was first used to probe the ground state and ZEB in Ni-Mn-based alloys. • A pure spin-glass ground state is proposed in Mn{sub 50}Ni{sub 41}Sn{sub 9} ribbon. • Field-induced nucleation and growth of ferromagnetic domains in SG results in ZEB.

  5. Bias against research on gender bias.

    Science.gov (United States)

    Cislak, Aleksandra; Formanowicz, Magdalena; Saguy, Tamar

    2018-01-01

    The bias against women in academia is a documented phenomenon that has had detrimental consequences, not only for women, but also for the quality of science. First, gender bias in academia affects female scientists, resulting in their underrepresentation in academic institutions, particularly in higher ranks. The second type of gender bias in science relates to some findings applying only to male participants, which produces biased knowledge. Here, we identify a third potentially powerful source of gender bias in academia: the bias against research on gender bias. In a bibliometric investigation covering a broad range of social sciences, we analyzed published articles on gender bias and race bias and established that articles on gender bias are funded less often and published in journals with a lower Impact Factor than articles on comparable instances of social discrimination. This result suggests the possibility of an underappreciation of the phenomenon of gender bias and related research within the academic community. Addressing this meta-bias is crucial for the further examination of gender inequality, which severely affects many women across the world.

  6. Identification and weighting factors influencing the establishment of a single minute exchange of dies in plastic injection industry using VIKOR and Shannon Entropy

    Directory of Open Access Journals (Sweden)

    Gholam Reza Hashemzadeh

    2014-05-01

    Full Text Available Single minute exchange of dies (SMED is one of the most important tools to achieve lean production system. The main idea of this system is to provide methods and to use creative and innovative solutions for continuous improvement. Due to the importance of this issue and its effect on reducing waste during the production process, this study presents a method to identify and to weight factors in the establishment of a single minute exchange of dies in 14 plastic injection factories. In this study, fourteen factories in injection industry were chosen and the factors influencing the implementation of single minute exchange of dies were identified. Following data collection, decision matrix was formed and the weight of each factor was determined by using Shannon Entropy. Then, in order to determine the readiness of factories, VIKOR method was used to rank companies. The results indicate priorities of the following factors in establishing SMED that include: Senior management support, technical capabilities, technical knowledge of staff and consultants, knowledge of mold design, manufacturing infrastructure, team work, combination of the project team work, benchmarking, training, clear understanding of project objectives, rewards and motivation, proper management expectation, project management, teamwork and organizational culture. Practical implications: Due to the factors, Top manager can make the best decision for implementing of SMED technique. This study develops factors influencing on SMED implementation based on Shannon and VIKOR methods for ranking parameters and plants.

  7. Thickness and bilayer number dependence on exchange bias in ferromagnetic/antiferromagnetic multilayers based on La{sub 1−x}Ca{sub x}MnO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Restrepo-Parra, E., E-mail: erestrepopa@unal.edu.co [Departamento de Física y Química, Universidad Nacional de Colombia-Sede Manizales, A.A. 127 Manizales (Colombia); Agudelo-Giraldo, J.D. [Departamento de Física y Química, Universidad Nacional de Colombia-Sede Manizales, A.A. 127 Manizales (Colombia); Grupo de Investigación y Desarrollo en Informática y Telecomunicaciones, Universidad de Manizales, Manizales (Colombia); Restrepo, J. [Grupo de Magnetismo y Simulación, Instituto de Física, Universidad de Antioquia, A.A. 1226 Medellín (Colombia)

    2014-05-01

    In this work, simulations of ferromagnetic/antiferromagnetic multilayers of La{sub 1−x}Ca{sub x}MnO{sub 3} have been carried out by using the Monte Carlo method combined with the Metropolis algorithm and the classical Heisenberg model. In the Hamiltonian we have considered three contributions: nearest neighbor exchange interaction, magnetocrystalline anisotropy and Zeeman interaction. Samples were built by including three types of Mn ions depending on their valence state and type of ionic orbital. Both the number of layers and the antiferromagnetic layer thickness influence on the exchange bias phenomenon are analyzed. Hysteresis loops results exhibit not only a shift as evidence of exchange bias but also the formation of plateaus or steps caused by the presence of more than one interface and the low layers thickness. Each layer presents a strong magnetic behavior because the magneto static energy favors formation of multi-domains in contrast with the single-domains of a single layer FM producing one sub-Loop of each domain (each layer). On the other hand, as the number of layers (n) increases, the sub-cycles tend to disappear. As the plateaus disappear, the system is more effective, increasing the coercive and bias fields. Moreover, domain sizes (layers thickness) also affect the shape of the hysteresis loop. On increasing the thickness of the AFM layer, a decrease in the plateaus produced by the uncoupling is generated.

  8. Australia's Bond Home Bias

    OpenAIRE

    Anil V. Mishra; Umaru B. Conteh

    2014-01-01

    This paper constructs the float adjusted measure of home bias and explores the determinants of bond home bias by employing the International Monetary Fund's high quality dataset (2001 to 2009) on cross-border bond investment. The paper finds that Australian investors' prefer investing in countries with higher economic development and more developed bond markets. Exchange rate volatility appears to be an impediment for cross-border bond investment. Investors prefer investing in countries with ...

  9. Media Bias

    OpenAIRE

    Sendhil Mullainathan; Andrei Shleifer

    2002-01-01

    There are two different types of media bias. One bias, which we refer to as ideology, reflects a news outlet's desire to affect reader opinions in a particular direction. The second bias, which we refer to as spin, reflects the outlet's attempt to simply create a memorable story. We examine competition among media outlets in the presence of these biases. Whereas competition can eliminate the effect of ideological bias, it actually exaggerates the incentive to spin stories.

  10. The Rac-specific exchange factors Dock1 and Dock5 are dispensable for the establishment of the glomerular filtration barrier in vivo.

    Science.gov (United States)

    Laurin, Mélanie; Dumouchel, Annie; Fukui, Yoshinori; Côté, Jean-François

    2013-01-01

    Podocytes are specialized kidney cells that form the kidney filtration barrier through the connection of their foot processes. Nephrin and Neph family transmembrane molecules at the surface of podocytes interconnect to form a unique type of cell-cell junction, the slit diaphragm, which acts as a molecular sieve. The cytoplasmic tails of Nephrin and Neph mediate cytoskeletal rearrangement that contributes to the maintenance of the filtration barrier. Nephrin and Neph1 orthologs are essential to regulate cell-cell adhesion and Rac-dependent actin rearrangement during Drosophila myoblast fusion. We hypothesized here that molecules regulating myoblast fusion in Drosophila could contribute to signaling downstream of Nephrin and Neph1 in podocytes. We found that Nephrin engagement promoted recruitment of the Rac exchange factor Dock1 to the membrane. Furthermore, Nephrin overexpression led to lamellipodia formation that could be blocked by inhibiting Rac1 activity. We generated in vivo mouse models to investigate whether Dock1 and Dock5 contribute to the formation and maintenance of the kidney filtration barrier. Our results indicate that while Dock1 and Dock5 are expressed in podocytes, their functions are not essential for the development of the glomerular filtration barrier. Furthermore, mice lacking Dock1 were not protected from LPS-induced podocyte effacement. Our data suggest that Dock1 and Dock5 are not the important exchange factors regulating Rac activity during the establishment and maintenance of the glomerular barrier.

  11. Room temperature magnetic ordering, enhanced magnetization and exchange bias of GdMnO3 nanoparticles in (GdMnO3)0.70(CoFe2O4)0.30

    International Nuclear Information System (INIS)

    Mitra, A.; Mahapatra, A.S.; Mallick, A.; Chakrabarti, P.K.

    2017-01-01

    Nanoparticles of GdMnO 3 (GMO) are prepared by sol-gel method. To enhance the magnetic property and also to obtain the magnetic ordering at room temperature (RT), nanoparticles of GMO are incorporated in the matrix of CoFe 2 O 4 (CFO). Desired crystallographic phases of CFO, GMO and GMO-CFO are confirmed by analyzing X-ray diffractrograms (XRD) using Rietveld method. The average size of nanoparticles and their distribution, crystallographic phase, nanocrystallinity etc. are studied by high-resolution transmission electron microscope (HRTEM). Magnetic hysteresis loops (M-H) of GMO-CFO under zero field cooled (ZFC) and field cooled (FC) conditions are observed at different temperatures down to 5 K. Magnetization vs. temperature (M-T) under ZFC and FC conditions are also recorded. Interestingly, exchange bias (EB) is found at low temperature which suggests the encapsulation of the ferromagnetic (FM) nanoparticles of GMO by the ferrimagnetic nanoparticles of CFO below ~100 K. Enhanced magnetization, EB effect and RT magnetic ordering of GMO-CFO would be interesting for both theoretical and experimental investigations. - Highlights: • Nanoparticles of GdMnO 3 are incorporated in the matrix of CoFe 2 O 4 . • RT magnetic ordering of GMO nanoparticles in GMO-CFO is observed. • Magnetic property of GMO-CFO is highly enhanced compared to GMO. • Exchange bias is found in GMO-CFO at low temperature.

  12. Exchange-bias effect at La0.75Sr0.25MnO3/LaNiO3 interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Rojas Sánchez, J. C. [Centro Atomico Bariloche-CNEA, Rio Negro (Argentina); National Scientific and Technical Research Council, Buenos Aires (Argentina); Nelson-Cheeseman, B. [Univ. of California, Berkeley, CA (United States); Granada, M. [Centro Atomico Bariloche-CNEA, Rio Negro (Argentina); National Scientific and Technical Research Council, Buenos Aires (Argentina); Arenholz, E. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS); Steren, L. B. [National Scientific and Technical Research Council, Buenos Aires (Argentina); Centro Atomico Constituyentes-CNEA, San Martin (Argentina)

    2012-03-26

    In this paper, we show that ferromagnetic/paramagnetic La0.75Sr0.25MnO3/LaNiO3 multilayers present an unexpected magnetic exchange-bias effect (EBE), observed in field-cooled magnetization loops. The exchange-bias field and the enhancement of the coercivity vanish around 50 K. We demonstrate that the oxidation state of the Ni and Mn cations changes from Mn3+-Ni3+ to Mn4+-Ni2+ in the layers close to the interface probed by x-ray absorption spectroscopy measurements. The variation of the valence states is accompanied by a change in the magnetic behavior of the cations at the La0.75Sr0.25MnO3/LaNiO3 interface, possibly giving rise to the formation of magnetic or magnetically frustrated regions that may pin the ferromagnetic a0.75Sr0.25MnO3 layers and explain the EBE.

  13. Antisite-disorder driven large exchange bias effect in phase separated La{sub 1.5}Ca{sub 0.5}CoMnO{sub 6} double perovskite

    Energy Technology Data Exchange (ETDEWEB)

    Sahoo, R.C.; Paladhi, D. [Department of Physics, Indian Institute of Technology Kharagpur, West Bengal 721302 (India); Dasgupta, Papri; Poddar, A. [Experimental Condensed Matter Physics Division, Saha Institute of Nuclear Physics, West Bengal (India); Singh, Ripandeep; Das, A. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Nath, T.K., E-mail: tnath@phy.iitkgp.ernet.in [Department of Physics, Indian Institute of Technology Kharagpur, West Bengal 721302 (India)

    2017-04-15

    Investigations of structural and magnetic properties of polycrystalline hole doped double perovskite La{sub 1.5}Ca{sub 0.5}CoMnO{sub 6} has clearly revealed the existence of structural antisite-disorder (either, Co–O–Co or Mn–O–Mn) in the system. The ordering of Co{sup 2+} and Mn{sup 4+} gives rise to a ferromagnetic transition around 157 K. A spin-canted antiferromagnetic transition is found in this material at T{sub CAFM} ~9 K. The effect of antisite-disorder in the double perovskite structure is most likely the prime reason for antiferromagnetic interaction. The temperature dependent inverse susceptibility exhibits Curie-Weiss like behaviour and it yields an effective paramagnetic moment of 6.49 μ{sub B}. At very low temperature (Texchange bias (EB) field of H{sub EB} ~5.5 kOe and can be tuned by the cooling field. The presence of zero-field cooled spontaneous EB effect (P-type and N-type) is confirmed to be not an experimental artefact - an inherent property of this double perovskite material. A phenomenological model has been proposed to explain the exchange coupling between the ferromagnetic and canted-antiferromagnetic interfaces of antisite-disordered La{sub 1.5}Ca{sub 0.5}CoMnO{sub 6} mainly on the basis of uncompensated interface spins. - Highlights: • Large exchange bias (EB) effect has been observed in 25% Ca doped La{sub 2}CoMnO{sub 6} antisite-disordered system. • Neutron powder diffraction analysis clearly suggested canted antiferromagnetic spin ordering at low temperature in our phase separated system. • A phenomenological model has been proposed for experimental results. • The results may be useful to acquire enough information about exchange biased interfaces for various magnetic device applications.

  14. Surface spin glass and exchange bias effect in Sm0.5Ca0.5MnO3 manganites nano particles

    Directory of Open Access Journals (Sweden)

    S. K. Giri

    2011-09-01

    Full Text Available In this letter, we report that the charge/orbital order state of bulk antiferromagnetic Sm0.5Ca0.5MnO3 is suppressed and confirms the appearance of weak ferromagnetism below 65 K followed by a low temperature spin glass like transition at 41 K in its nano metric counterpart. Exchange anisotropy effect has been observed in the nano manganites and can be tuned by the strength of the cooling magnetic field (Hcool. The values of exchange fields (HE, coercivity (HC, remanence asymmetry (ME and magnetic coercivity (MC are found to strongly depend on cooling magnetic field and temperature. HE increases with increasing Hcool but for larger Hcool, HE tends to decrease due to the growth of ferromagnetic cluster size. Magnetic training effect has also been observed and it has been analyzed thoroughly using spin relaxation model. A proposed phenomenological core-shell type model is attributed to an exchange coupling between the spin-glass like shell (surrounding and antiferromagnetic core of Sm0.5Ca0.5MnO3 nano manganites mainly on the basis of uncompensated surface spins. Results suggest that the intrinsic phase inhomogeneity due to the surface effects of the nanostructured manganites may cause exchange anisotropy, which is of special interests for potential application in multifunctional spintronic devices.

  15. Evidence of spin-glass like ordering and exchange bias effect in antisite-disordered nanometric La1.5Ca0.5CoMnO6 double perovskite

    Science.gov (United States)

    Sahoo, R. C.; Paladhi, D.; Nath, T. K.

    2017-08-01

    Single-phase polycrystalline La1.5Ca0.5CoMnO6 double perovskite nanoparticles (∼25 nm) have been synthesized by chemical sol-gel method. We report here the structural, magnetic and transport properties using X-ray diffraction, dc magnetization, ac susceptibility, exchange bias and dc resistivity measurements. The Rietveld refinement of X-ray diffraction pattern reveals that the La1.5Ca0.5CoMnO6 (LCCMO) system crystallizes in orthorhombic structure with pbnm space group. Mn and Co ions are not completely ordered on the B sites due to the presence of about 30% antisite-disorder in the system. The ordering of Co2+ and Mn4+ gives rise to the ferromagnetism below 145 K. A spin glass like ground state has also been observed near 37.6(4) K, arising mainly due to the presence of competing magnetic interactions and antisite-disorder in the LCCMO nanoparticles. The frequency dependence peak shift of the Ac-susceptibility peak in the glassy state follows the critical slowing down model. The observed memory effect in ac susceptibility data reveals the existence of interacting clusters in a competing magnetic interactions state. The presence of noticeable exchange bias effect can be best explained on the basis of uncompensated interface (ferromagnetic/spin-glass) spins of antisite-disordered LCCMO system. This anti-site disordered nanocompound exhibits semiconducting behavior with variable range hopping kind of electronic conduction mechanism in the temperature range of 200-300 K. We have also observed large negative magnetoresistance (-30% at 100 K and 60 kOe) mainly due to the spin-polarized transport across the grain boundaries.

  16. Establishing the Next Generation at Work : Leader Generativity as a Moderator of the Relationships Between Leader Age, Leader-Member Exchange, and Leadership Success

    NARCIS (Netherlands)

    Zacher, Hannes; Rosing, Kathrin; Henning, Thomas; Frese, Michael

    In this study, the authors investigated leader generativity as a moderator of the relationships between leader age, leader-member exchange, and three criteria of leadership success (follower perceptions of leader effectiveness, follower satisfaction with leader, and follower extra effort). Data came

  17. Evidence of spin-glass like ordering and exchange bias effect in antisite-disordered nanometric La{sub 1.5}Ca{sub 0.5}CoMnO{sub 6} double perovskite

    Energy Technology Data Exchange (ETDEWEB)

    Sahoo, R.C.; Paladhi, D.; Nath, T.K., E-mail: tnath@phy.iitkgp.ernet.in

    2017-08-15

    Highlights: • SG has been observed due to antisite disorder and different magnetic interactions. • The observed EB can be best explained on the basis of uncompensated interface spins. • −30% MR has been observed due to the spin-polarized transport at grain boundaries. - Abstract: Single-phase polycrystalline La{sub 1.5}Ca{sub 0.5}CoMnO{sub 6} double perovskite nanoparticles (∼25 nm) have been synthesized by chemical sol-gel method. We report here the structural, magnetic and transport properties using X-ray diffraction, dc magnetization, ac susceptibility, exchange bias and dc resistivity measurements. The Rietveld refinement of X-ray diffraction pattern reveals that the La{sub 1.5}Ca{sub 0.5}CoMnO{sub 6} (LCCMO) system crystallizes in orthorhombic structure with pbnm space group. Mn and Co ions are not completely ordered on the B sites due to the presence of about 30% antisite-disorder in the system. The ordering of Co{sup 2+} and Mn{sup 4+} gives rise to the ferromagnetism below 145 K. A spin glass like ground state has also been observed near 37.6(4) K, arising mainly due to the presence of competing magnetic interactions and antisite-disorder in the LCCMO nanoparticles. The frequency dependence peak shift of the Ac-susceptibility peak in the glassy state follows the critical slowing down model. The observed memory effect in ac susceptibility data reveals the existence of interacting clusters in a competing magnetic interactions state. The presence of noticeable exchange bias effect can be best explained on the basis of uncompensated interface (ferromagnetic/spin-glass) spins of antisite-disordered LCCMO system. This anti-site disordered nanocompound exhibits semiconducting behavior with variable range hopping kind of electronic conduction mechanism in the temperature range of 200–300 K. We have also observed large negative magnetoresistance (−30% at 100 K and 60 kOe) mainly due to the spin-polarized transport across the grain boundaries.

  18. Journal bias or author bias?

    Science.gov (United States)

    Harris, Ian

    2016-01-01

    I read with interest the comment by Mark Wilson in the Indian Journal of Medical Ethics regarding bias and conflicts of interest in medical journals. Wilson targets one journal (the New England Journal of Medicine: NEJM) and one particular "scandal" to make his point that journals' decisions on publication are biased by commercial conflicts of interest (CoIs). It is interesting that he chooses the NEJM which, by his own admission, had one of the strictest CoI policies and had published widely on this topic. The feeling is that if the NEJM can be guilty, they can all be guilty.

  19. Referee Bias

    OpenAIRE

    Dohmen, Thomas; Sauermann, Jan

    2015-01-01

    This paper surveys the empirical literature on the behavior of referees in professional football and other sports. Referees are typically appointed by a principal to be impartial, especially when unbiased referee judgment is vital for the accomplishment of the principal's objective. Answering whether referees make biased decisions and understanding the causes that lead referees to digress from their principal duty of impartiality is therefore fundamental from a theoretical point of view. At t...

  20. Establishing the next generation at work: leader generativity as a moderator of the relationships between leader age, leader-member exchange, and leadership success.

    Science.gov (United States)

    Zacher, Hannes; Rosing, Kathrin; Henning, Thomas; Frese, Michael

    2011-03-01

    In this study, the authors investigated leader generativity as a moderator of the relationships between leader age, leader-member exchange, and three criteria of leadership success (follower perceptions of leader effectiveness, follower satisfaction with leader, and follower extra effort). Data came from 128 university professors paired with one research assistant each. Results showed positive relationships between leader age and leader generativity, and negative relationships between leader age and follower perceptions of leader effectiveness and follower extra effort. Consistent with expectations based on leadership categorization theory, leader generativity moderated the relationships between leader age and all three criteria of leadership success, such that leaders high in generativity were better able to maintain high levels of leadership success at higher ages than leaders low in generativity. Finally, results of mediated moderation analyses showed that leader-member exchange quality mediated these moderating effects. The findings suggest that, in combination, leader age and the age-related construct of generativity importantly influence leadership processes and outcomes. (c) 2011 APA, all rights reserved.

  1. Size-dependent multiple magnetic phases and exchange bias effect in hole-doped double perovskite La1.6Sr0.4NiMnO6

    International Nuclear Information System (INIS)

    Liu, Wenjie; Shi, Lei; Zhou, Shiming; Zhao, Jiyin; Li, Yang; Guo, Yuqiao

    2014-01-01

    La 1.6 Sr 0.4 NiMnO 6 nanoparticles of different sizes (18–150 nm) have been prepared by a sol–gel method, and the size effects on their magnetic properties are investigated. It is found that there is a ferromagnetic (FM) transition at T C  ∼ 245 K for the sample with particle size D ∼ 150 nm. As the particle size decreases, a spin glass (SG) transition appears at T G  ∼ 60 K and becomes more obvious. Meanwhile, the T C shifts to a lower temperature and the FM transition becomes indistinct. The size dependent saturation magnetization M S , which is in the range 0.78 ∼ 1.27 μ B /f.u., shows a non-monotonic variation with a maximum of 1.27 μ B /f.u. at the particle size D C  ∼ 42 nm. The exchange bias (EB) effect is clearly observed for D > 32 nm and becomes indistinct as D ⩽ 32 nm. As the particle size decreasing, the EB field H E decreases and becomes near nil at D C . Meanwhile, the coercive field H C first increases to a maximum at D C and then decreases. All the results indicate the coexistence of AFM APBs related to the anti-site disorders, FM domains, and SG phase in La 1.6 Sr 0.4 NiMnO 6 nanoparticles. The magnetic properties of the nanoparticles are understood by a complex core-shell model, i.e. both AFM APBs and FM domains coexist in the core, and the SG phase mainly resides on the surface (shell) of each particle, which reveals that the size effects on the FM phase, AFM APBs and surface SG phase in grain are different, even are opposite. The nanometer size effect is a crucial factor to influence the magnetic properties of La 1.6 Sr 0.4 NiMnO 6 nanoparticles. (paper)

  2. An inclusive taxonomy of behavioral biases

    Directory of Open Access Journals (Sweden)

    David Peón

    2017-07-01

    Full Text Available This paper overviews the theoretical and empirical research on behavioral biases and their influence in the literature. To provide a systematic exposition, we present a unified framework that takes the reader through an original taxonomy, based on the reviews of relevant authors in the field. In particular, we establish three broad categories that may be distinguished: heuristics and biases; choices, values and frames; and social factors. We then describe the main biases within each category, and revise the main theoretical and empirical developments, linking each bias with other biases and anomalies that are related to them, according to the literature.

  3. Political Accountability, Electoral Control, and Media Bias

    OpenAIRE

    Takanori Adachi; Yoichi Hizen

    2012-01-01

    Are anti-establishment mass media really useful in preventing politicians from behaving dishonestly? This paper proposes a voting model for analyzing how differences in the direction of media bias affect politicians' behavior. In particular, the probability of corruption by an incumbent is higher (than that in the case of no media bias) if and only if the mass media have some degree of "anti-incumbent" bias (i.e., information favorable to the incumbent is converted into unfavorable news about...

  4. Room temperature magnetic ordering, enhanced magnetization and exchange bias of GdMnO{sub 3} nanoparticles in (GdMnO{sub 3}){sub 0.70}(CoFe{sub 2}O{sub 4}){sub 0.30}

    Energy Technology Data Exchange (ETDEWEB)

    Mitra, A.; Mahapatra, A.S.; Mallick, A.; Chakrabarti, P.K., E-mail: pabitra_c@hotmail.com

    2017-02-15

    Nanoparticles of GdMnO{sub 3} (GMO) are prepared by sol-gel method. To enhance the magnetic property and also to obtain the magnetic ordering at room temperature (RT), nanoparticles of GMO are incorporated in the matrix of CoFe{sub 2}O{sub 4} (CFO). Desired crystallographic phases of CFO, GMO and GMO-CFO are confirmed by analyzing X-ray diffractrograms (XRD) using Rietveld method. The average size of nanoparticles and their distribution, crystallographic phase, nanocrystallinity etc. are studied by high-resolution transmission electron microscope (HRTEM). Magnetic hysteresis loops (M-H) of GMO-CFO under zero field cooled (ZFC) and field cooled (FC) conditions are observed at different temperatures down to 5 K. Magnetization vs. temperature (M-T) under ZFC and FC conditions are also recorded. Interestingly, exchange bias (EB) is found at low temperature which suggests the encapsulation of the ferromagnetic (FM) nanoparticles of GMO by the ferrimagnetic nanoparticles of CFO below ~100 K. Enhanced magnetization, EB effect and RT magnetic ordering of GMO-CFO would be interesting for both theoretical and experimental investigations. - Highlights: • Nanoparticles of GdMnO{sub 3} are incorporated in the matrix of CoFe{sub 2}O{sub 4}. • RT magnetic ordering of GMO nanoparticles in GMO-CFO is observed. • Magnetic property of GMO-CFO is highly enhanced compared to GMO. • Exchange bias is found in GMO-CFO at low temperature.

  5. Approach to Exchange Bias Effect in La2/3Ca1/3MnO3/BiFeO3 and BiFeO3/ La2/3Ca1/3MnO3 Bilayers

    Science.gov (United States)

    Dominguez, Claribel; Ordonez, John; Diez, Sandra; Gomez, Maria; Guénon, Stefan; Schuller, Ivan

    2013-03-01

    We have grown bilayers of ferromagnetic La2/3Ca1/3MnO3 (LCMO) and multiferroic BiFeO3 (BFO) on (100) SrTiO3 (STO) substrates, by DC- and magnetron RF -sputtering technique, respectively, at high-oxygen pressures. We maintain constant the thickness of the layers (tBFO=72nm; tLCMO=80nm). Temperature dependence of the resistivity indicates that the MI-transition temperature of the manganite in the BFO/LCMO/STO is affected by the presence of the BFO layer in comparison with TMI for the single LCMO layer. Furthermore, temperature dependence of magnetization shows that the BFO/LCMO/STO bilayer has higher Curie temperature than that for LCMO/BFO/STO, indicating a strong structural dependence of the LCMO layer with magnetic response. The dependence of the magnetic moment with magnetic field after field cooling gives indication of the existence of Exchange Bias effect in the LCMO/BFO/STO bilayer. Isothermal loops also display dependence of the Exchange Bias magnitude with field cooling. This work has been supported by UNIVALLE Research Project CI 7864, and ``El Patrimonio Autónomo Fondo Nacional de Financiamiento para CT&I FJC,'' Contract RC - No. 275-2011, COLCIENCIAS-CENM, Colombia

  6. Exchange transfusion

    Science.gov (United States)

    ... count in a newborn (neonatal polycythemia) Rh-induced hemolytic disease of the newborn Severe disturbances in body chemistry Severe newborn jaundice ... exchange transfusion was performed to treat. Alternative Names Hemolytic disease - exchange transfusion Patient ... Exchange transfusion - series References Costa ...

  7. Benefits of being biased!

    Indian Academy of Sciences (India)

    Administrator

    Keywords. codon bias; alcohol dehydrogenase; Darwinian fitness; Drosophila melanogaster. RESEARCH COMMENTARY. Benefits of being biased! SUTIRTH DEY*. Evolutionary Biology Laboratory, Evolutionary & Organismal Biology Unit,. Jawaharlal Nehru Centre for Advanced Scientific Research,. Jakkur P.O. Box 6436 ...

  8. Contextual modulation of biases in face recognition.

    Directory of Open Access Journals (Sweden)

    Fatima Maria Felisberti

    Full Text Available BACKGROUND: The ability to recognize the faces of potential cooperators and cheaters is fundamental to social exchanges, given that cooperation for mutual benefit is expected. Studies addressing biases in face recognition have so far proved inconclusive, with reports of biases towards faces of cheaters, biases towards faces of cooperators, or no biases at all. This study attempts to uncover possible causes underlying such discrepancies. METHODOLOGY AND FINDINGS: Four experiments were designed to investigate biases in face recognition during social exchanges when behavioral descriptors (prosocial, antisocial or neutral embedded in different scenarios were tagged to faces during memorization. Face recognition, measured as accuracy and response latency, was tested with modified yes-no, forced-choice and recall tasks (N = 174. An enhanced recognition of faces tagged with prosocial descriptors was observed when the encoding scenario involved financial transactions and the rules of the social contract were not explicit (experiments 1 and 2. Such bias was eliminated or attenuated by making participants explicitly aware of "cooperative", "cheating" and "neutral/indifferent" behaviors via a pre-test questionnaire and then adding such tags to behavioral descriptors (experiment 3. Further, in a social judgment scenario with descriptors of salient moral behaviors, recognition of antisocial and prosocial faces was similar, but significantly better than neutral faces (experiment 4. CONCLUSION: The results highlight the relevance of descriptors and scenarios of social exchange in face recognition, when the frequency of prosocial and antisocial individuals in a group is similar. Recognition biases towards prosocial faces emerged when descriptors did not state the rules of a social contract or the moral status of a behavior, and they point to the existence of broad and flexible cognitive abilities finely tuned to minor changes in social context.

  9. Contextual modulation of biases in face recognition.

    Science.gov (United States)

    Felisberti, Fatima Maria; Pavey, Louisa

    2010-09-23

    The ability to recognize the faces of potential cooperators and cheaters is fundamental to social exchanges, given that cooperation for mutual benefit is expected. Studies addressing biases in face recognition have so far proved inconclusive, with reports of biases towards faces of cheaters, biases towards faces of cooperators, or no biases at all. This study attempts to uncover possible causes underlying such discrepancies. Four experiments were designed to investigate biases in face recognition during social exchanges when behavioral descriptors (prosocial, antisocial or neutral) embedded in different scenarios were tagged to faces during memorization. Face recognition, measured as accuracy and response latency, was tested with modified yes-no, forced-choice and recall tasks (N = 174). An enhanced recognition of faces tagged with prosocial descriptors was observed when the encoding scenario involved financial transactions and the rules of the social contract were not explicit (experiments 1 and 2). Such bias was eliminated or attenuated by making participants explicitly aware of "cooperative", "cheating" and "neutral/indifferent" behaviors via a pre-test questionnaire and then adding such tags to behavioral descriptors (experiment 3). Further, in a social judgment scenario with descriptors of salient moral behaviors, recognition of antisocial and prosocial faces was similar, but significantly better than neutral faces (experiment 4). The results highlight the relevance of descriptors and scenarios of social exchange in face recognition, when the frequency of prosocial and antisocial individuals in a group is similar. Recognition biases towards prosocial faces emerged when descriptors did not state the rules of a social contract or the moral status of a behavior, and they point to the existence of broad and flexible cognitive abilities finely tuned to minor changes in social context.

  10. Matchmaker Exchange.

    Science.gov (United States)

    Sobreira, Nara L M; Arachchi, Harindra; Buske, Orion J; Chong, Jessica X; Hutton, Ben; Foreman, Julia; Schiettecatte, François; Groza, Tudor; Jacobsen, Julius O B; Haendel, Melissa A; Boycott, Kym M; Hamosh, Ada; Rehm, Heidi L

    2017-10-18

    In well over half of the individuals with rare disease who undergo clinical or research next-generation sequencing, the responsible gene cannot be determined. Some reasons for this relatively low yield include unappreciated phenotypic heterogeneity; locus heterogeneity; somatic and germline mosaicism; variants of uncertain functional significance; technically inaccessible areas of the genome; incorrect mode of inheritance investigated; and inadequate communication between clinicians and basic scientists with knowledge of particular genes, proteins, or biological systems. To facilitate such communication and improve the search for patients or model organisms with similar phenotypes and variants in specific candidate genes, we have developed the Matchmaker Exchange (MME). MME was created to establish a federated network connecting databases of genomic and phenotypic data using a common application programming interface (API). To date, seven databases can exchange data using the API (GeneMatcher, PhenomeCentral, DECIPHER, MyGene2, matchbox, Australian Genomics Health Alliance Patient Archive, and Monarch Initiative; the latter included for model organism matching). This article guides usage of the MME for rare disease gene discovery. © 2017 by John Wiley & Sons, Inc. Copyright © 2017 John Wiley and Sons, Inc.

  11. Barter exchanges

    DEFF Research Database (Denmark)

    Sudzina, Frantisek

    Although barter is often perceived as something that proceeded money, barter is still used. The focus of the paper is on barter exchanges. Barter exchanges are used both in developing countries as well as in developed countries (including the U.S.). They are used by both organizations...... and individuals. They usually allow to exchange good but some include also services. Some exchanges allow only for bi-directional barter, i.e. when only two parties are involved in the exchange. But probably most of the barter exchanges use barter money; this makes it easier to exchange goods and services...

  12. Bond and Equity Home Bias and Foreign Bias: an International Study

    OpenAIRE

    VanPée, Rosanne; De Moor, Lieven

    2012-01-01

    In this paper we explore tentatively and formally the differences between bond and equity home bias and foreign bias based on one large scale dataset including developed and emerging markets for the period 2001 to 2010. We set the stage by tentatively and formally linking the diversion of bond and equity home bias in OECD countries to the increasing public debt issues under the form of government bonds i.e. the supply-driven argument. Unlike Fidora et al. (2007) we do not find that exchange r...

  13. The meaning of the bias uncertainty measure.

    Science.gov (United States)

    Bartley, David L

    2008-08-01

    Characterization of measurement uncertainty in terms of root sums of squares of both unknown systematic as well as random error components is given meaning in the sense of prediction intervals. Both types of errors are commonly encountered with industrial hygiene air monitoring of hazardous substances. Two extreme types of measurement methods are presented for illustrating how confidence levels may be ascribed to prediction intervals defined by such uncertainty values. In the case of method calibration at each measurement, systematic error or bias may enter from a biased calibrant. At another extreme, a single initial method evaluation may leave residual bias owing to random error in the evaluation itself or to the use of a biased reference method. Analysis is simplified through new simple approximations to probabilistic limits (quantiles) on the magnitude of a non-central Student t-distributed random variable. Connection is established between traditional confidence limits, accuracy measures in the case of bias minimization and an uncertainty measure.

  14. CPI Bias in Korea

    Directory of Open Access Journals (Sweden)

    Chul Chung

    2007-12-01

    Full Text Available We estimate the CPI bias in Korea by employing the approach of Engel’s Law as suggested by Hamilton (2001. This paper is the first attempt to estimate the bias using Korean panel data, Korean Labor and Income Panel Study(KLIPS. Following Hamilton’s model with non­linear specification correction, our estimation result shows that the cumulative CPI bias over the sample period (2000-2005 was 0.7 percent annually. This CPI bias implies that about 21 percent of the inflation rate during the period can be attributed to the bias. In light of purchasing power parity, we provide an interpretation of the estimated bias.

  15. Bias in research.

    Science.gov (United States)

    Simundić, Ana-Maria

    2013-01-01

    By writing scientific articles we communicate science among colleagues and peers. By doing this, it is our responsibility to adhere to some basic principles like transparency and accuracy. Authors, journal editors and reviewers need to be concerned about the quality of the work submitted for publication and ensure that only studies which have been designed, conducted and reported in a transparent way, honestly and without any deviation from the truth get to be published. Any such trend or deviation from the truth in data collection, analysis, interpretation and publication is called bias. Bias in research can occur either intentionally or unintentionally. Bias causes false conclusions and is potentially misleading. Therefore, it is immoral and unethical to conduct biased research. Every scientist should thus be aware of all potential sources of bias and undertake all possible actions to reduce or minimize the deviation from the truth. This article describes some basic issues related to bias in research.

  16. On commercial media bias

    OpenAIRE

    Germano, Fabrizio

    2008-01-01

    Within the spokes model of Chen and Riordan (2007) that allows for non-localized competition among arbitrary numbers of media outlets, we quantify the effect of concentration of ownership on quality and bias of media content. A main result shows that too few commercial outlets, or better, too few separate owners of commercial outlets can lead to substantial bias in equilibrium. Increasing the number of outlets (commercial and non-commercial) tends to bring down this bias; but the strongest ef...

  17. Wage Changes, Establishment Growth, and the Effect of Composition Bias

    OpenAIRE

    Monica Galizzi

    2007-01-01

    The correlation between real wages and aggregate employment growth has beenthe object of several empirical studies conducted with both aggregate and micro data.Despite the new availability of linked employer-employee data, however, we still havelimited empirical evidence [Belzil, 2000] to describe how real wage cyclicality can beexplained by what happens between workers and employers at the firm level. Thispaper makes a contribution by making use of Italian data to explore whether a posi-tive...

  18. Simulating publication bias

    DEFF Research Database (Denmark)

    Paldam, Martin

    are made by data variation, while the model is the same. It appears that SR0 generates narrow funnels much at odds with observed funnels, while the other four funnels look more realistic. SR1 to SR4 give the mean a substantial bias that confirms the prior causing the bias. The FAT-PET MRA works well...

  19. Biases in categorization

    NARCIS (Netherlands)

    Das-Smaal, E.A.

    1990-01-01

    On what grounds can we conclude that an act of categorization is biased? In this chapter, it is contended that in the absence of objective norms of what categories actually are, biases in categorization can only be specified in relation to theoretical understandings of categorization. Therefore, the

  20. Heat exchanger

    International Nuclear Information System (INIS)

    Dostatni, A.W.; Dostatni, Michel.

    1976-01-01

    In the main patent, a description was given of a heat exchanger with an exchange surface in preformed sheet metal designed for the high pressure and temperature service particularly encountered in nuclear pressurized water reactors and which is characterised by the fact that it is composed of at least one exchanger bundle sealed in a containment, the said bundle or bundles being composed of numerous juxtaposed individual compartments whose exchange faces are built of preformed sheet metal. The present addendun certificate concerns shapes of bundles and their positioning methods in the exchanger containment enabling its compactness to be increased [fr

  1. A new family of 1D exchange biased heterometal single-molecule magnets: observation of pronounced quantum tunneling steps in the hysteresis loops of quasi-linear {Mn2Ni3} clusters.

    Science.gov (United States)

    Das, Animesh; Gieb, Klaus; Krupskaya, Yulia; Demeshko, Serhiy; Dechert, Sebastian; Klingeler, Rüdiger; Kataev, Vladislav; Büchner, Bernd; Müller, Paul; Meyer, Franc

    2011-03-16

    First members of a new family of heterometallic Mn/Ni complexes [Mn(2)Ni(3)X(2)L(4)(LH)(2)(H(2)O)(2)] (X = Cl: 1; X = Br: 2) with the new ligand 2-{3-(2-hydroxyphenyl)-1H-pyrazol-1-yl}ethanol (H(2)L) have been synthesized, and single crystals obtained from CH(2)Cl(2) solutions have been characterized crystallographically. The molecular structures feature a quasi-linear Mn(III)-Ni(II)-Ni(II)-Ni(II)-Mn(III) core with six-coordinate metal ions, where elongated axes of all the distorted octahedral coordination polyhedra are aligned parallel and are fixed with respect to each other by intramolecular hydrogen bonds. 1 and 2 exhibit quite strong ferromagnetic exchange interactions throughout (J(Mn-Ni) ≈ 40 K (1) or 42 K (2); J(Ni-Ni) ≈ 22 K (1) or 18 K (2)) that lead to an S(tot) = 7 ground state, and a sizable uniaxial magnetoanisotropy with D(mol) values -0.55 K (1) and -0.45 K (2). These values are directly derived also from frequency- and temperature-dependent high-field EPR spectra. Slow relaxation of the magnetization at low temperatures and single-molecule magnet (SMM) behavior are evident from frequency-dependent peaks in the out-of-phase ac susceptibilities and magnetization versus dc field measurements, with significant energy barriers to spin reversal U(eff) = 27 K (1) and 22 K (2). Pronounced quantum tunnelling steps are observed in the hysteresis loops of the temperature- and scan rate-dependent magnetization data, but with the first relaxation step shifted above (1) or below (2) the zero crossing of the magnetic field, despite the very similar molecular structures. The different behavior of 1 and 2 is interpreted in terms of antiferromagnetic (1) or ferromagnetic (2) intermolecular interactions, which are discussed in view of the subtle differences of intermolecular contacts within the crystal lattice.

  2. Harassment, Bias, and Discrimination.

    Science.gov (United States)

    Welliver, Paul W.

    1995-01-01

    Discusses a new principle which has been added to the AECT (Association for Educational Communications and Technology) Code of Professional Ethics regarding discrimination, harassment, and bias. An example is presented which illustrates a violation of a professional colleague's rights. (LRW)

  3. Biases in casino betting

    Directory of Open Access Journals (Sweden)

    James Sundali

    2006-07-01

    Full Text Available We examine two departures of individual perceptions of randomness from probability theory: the hot hand and the gambler's fallacy, and their respective opposites. This paper's first contribution is to use data from the field (individuals playing roulette in a casino to demonstrate the existence and impact of these biases that have been previously documented in the lab. Decisions in the field are consistent with biased beliefs, although we observe significant individual heterogeneity in the population. A second contribution is to separately identify these biases within a given individual, then to examine their within-person correlation. We find a positive and significant correlation across individuals between hot hand and gambler's fallacy biases, suggesting a common (root cause of the two related errors. We speculate as to the source of this correlation (locus of control, and suggest future research which could test this speculation.

  4. Bias aware Kalman filters

    DEFF Research Database (Denmark)

    Drecourt, J.-P.; Madsen, H.; Rosbjerg, Dan

    2006-01-01

    This paper reviews two different approaches that have been proposed to tackle the problems of model bias with the Kalman filter: the use of a colored noise model and the implementation of a separate bias filter. Both filters are implemented with and without feedback of the bias into the model state...... are illustrated on a simple one-dimensional groundwater problem. The results show that the presented filters outperform the standard Kalman filter and that the implementations with bias feedback work in more general conditions than the implementations without feedback. 2005 Elsevier Ltd. All rights reserved........ The colored noise filter formulation is extended to correct both time correlated and uncorrelated model error components. A more stable version of the separate filter without feedback is presented. The filters are implemented in an ensemble framework using Latin hypercube sampling. The techniques...

  5. Gender-Biased Learning.

    Science.gov (United States)

    Weiss, Ruth Palombo

    2001-01-01

    Looks at how gender shapes the way humans learn from biological and sociological perspectives. Indicates that teachers interact more frequently with males and that trainers should try to overcome gender bias. Suggests that discrimination persists in adult education. (JOW)

  6. Heat exchanger

    International Nuclear Information System (INIS)

    Leigh, D.G.

    1976-01-01

    The arrangement described relates particularly to heat exchangers for use in fast reactor power plants, in which heat is extracted from the reactor core by primary liquid metal coolant and is then transferred to secondary liquid metal coolant by means of intermediate heat exchangers. One of the main requirements of such a system, if used in a pool type fast reactor, is that the pressure drop on the primary coolant side must be kept to a minimum consistent with the maintenance of a limited dynamic head in the pool vessel. The intermediate heat exchanger must also be compact enough to be accommodated in the reactor vessel, and the heat exchanger tubes must be available for inspection and the detection and plugging of leaks. If, however, the heat exchanger is located outside the reactor vessel, as in the case of a loop system reactor, a higher pressure drop on the primary coolant side is acceptable, and space restriction is less severe. An object of the arrangement described is to provide a method of heat exchange and a heat exchanger to meet these problems. A further object is to provide a method that ensures that excessive temperature variations are not imposed on welded tube joints by sudden changes in the primary coolant flow path. Full constructional details are given. (U.K.)

  7. Enhanced magnetic behavior, exchange bias effect, and dielectric property of BiFeO3 incorporated in (BiFeO30.50 (Co0.4Zn0.4Cu0.2 Fe2O40.5 nanocomposite

    Directory of Open Access Journals (Sweden)

    K. Mukhopadhyay

    2014-03-01

    Full Text Available Nanoparticles of BiFeO3 (BFO are incorporated in the nanocomposite of (BiFeO30.50 (Co0.4Zn0.4Cu0.2 Fe2O40.5, (BFO-CZCF and these are prepared by chemical route. The formation of pure crystallographic phase of each component (BFO and CZCF in the nanocomposite of BFO-CZCF has been confirmed by Rietveld analysis of the X-ray diffractograms using FULLPROF program. Morphology, average particle size and its distribution, crystallographic phase etc. are obtained from the high-resolution transmission electron microscopy of BFO-CZCF. Magnetic measurements of BFO-CZCF have been carried out to explore the modulation of magnetic behavior of BFO in BFO-CZCF. Interestingly, magnetization of BFO-CZCF has been drastically enhanced compared to that of the pristine BFO. An exchange bias effect is also observed in the M vs. H loops of BFO-CZCF recorded in field cooled and zero field cooled conditions, which suggest that nanoparticles of BFO (AFM are encapsulated by nanoparticles of CZCF (FM in BFO-CZCF. Thermal variation of dielectric constant of BFO-CZCF is recorded in the range of 300 to 1073 K and a ferroelectric to paraelectric transition is observed at ∼728 K. Enhanced magnetic property of BFO would quite interesting for this important multiferroic.

  8. Measuring Agricultural Bias

    DEFF Research Database (Denmark)

    Jensen, Henning Tarp; Robinson, Sherman; Tarp, Finn

    The measurement issue is the key issue in the literature on trade policy-induced agri-cultural price incentive bias. This paper introduces a general equilibrium effective rate of protection (GE-ERP) measure, which extends and generalizes earlier partial equilibrium nominal protection measures....... For the 15 sample countries, the results indicate that the agricultural price incentive bias, which was generally perceived to exist during the 1980s, was largely eliminated during the 1990s. The results also demonstrate that general equilibrium effects and country-specific characteristics - including trade...... shares and intersectoral linkages - are crucial for determining the sign and magnitude of trade policy bias. The GE-ERP measure is therefore uniquely suited to capture the full impact of trade policies on agricultural price incentives. A Monte Carlo procedure confirms that the results are robust...

  9. Obesity Stigma and Bias.

    Science.gov (United States)

    Fruh, Sharon M; Nadglowski, Joe; Hall, Heather R; Davis, Sara L; Crook, Errol D; Zlomke, Kimberly

    2016-01-01

    Overweight and obesity are escalating in epidemic proportions in the United States. Individuals with overweight and obesity are often reluctant to seek medical help, not only for weight reduction but also for any health issue because of perceived provider discrimination. Providers who are biased against individuals with obesity can hinder our nation's effort to effectively fight the obesity epidemic. By addressing weight bias in the provider setting, individuals affected by obesity may be more likely to engage in a meaningful and productive discussion of weight. Providers need to be the go-to source for obesity-focused information on new and emerging treatments.

  10. Measuring agricultural policy bias

    DEFF Research Database (Denmark)

    Jensen, Henning Tarp; Robinson, Sherman; Tarp, Finn

    2010-01-01

    Measurement is a key issue in the literature on price incentive bias induced by trade policy. We introduce a general equilibrium measure of the relative effective rate of protection, which generalizes earlier protection measures. For our fifteen sample countries, results indicate that the agricul......Measurement is a key issue in the literature on price incentive bias induced by trade policy. We introduce a general equilibrium measure of the relative effective rate of protection, which generalizes earlier protection measures. For our fifteen sample countries, results indicate...... protection measure is therefore uniquely suited to capture the full impact of trade policies on relative agricultural price incentives....

  11. HEAT EXCHANGER

    Science.gov (United States)

    Fox, T.H. III; Richey, T. Jr.; Winders, G.R.

    1962-10-23

    A heat exchanger is designed for use in the transfer of heat between a radioactive fiuid and a non-radioactive fiuid. The exchanger employs a removable section containing the non-hazardous fluid extending into the section designed to contain the radioactive fluid. The removable section is provided with a construction to cancel out thermal stresses. The stationary section is pressurized to prevent leakage of the radioactive fiuid and to maintain a safe, desirable level for this fiuid. (AEC)

  12. Heat exchanger

    International Nuclear Information System (INIS)

    Watabe, Ichiro.

    1996-01-01

    An inner cylinder is disposed coaxially in a vertical vessel, and a plurality of heat transfer pipes are wound spirally on the outer circumference of the inner cylinder. High temperature sodium descends on the outer side of the inner cylinder while exchanging heat with water in the heat transfer pipes and becomes low temperature sodium. The low temperature sodium turns at the lower portion of the vessel, rises in a sodium exit pipe inserted to the inner cylinder and is discharged from the top of the vessel to the outside of the vessel. A portion of a cover gas (an inert gas such as argon) filled to the upper portion of the vessel intrudes into the space between the outer circumference of the sodium exit pipe and the inner circumference of the inner cylinder to form a heat insulation layer of the inert gas. This prevents heat exchange between the high temperature sodium before heat exchange and low temperature sodium after heat exchange. The heat exchanger is used as a secondary heat exchanger for coolants (sodium) of an FBR type reactor. (I.N.)

  13. Weak ferromagnetism and exchange biasing in cobalt oxide nanoparticle systems

    NARCIS (Netherlands)

    Tomou, A; Gournis, D; Panagiotopoulos, [No Value; Huang, Y; Hadjipanayis, GC; Kooi, BJ; Panagiotopoulos, I.

    2006-01-01

    Cobalt oxide nanoparticle systems have been prepared by wet chemical processing involving the encapsulation of the nanoparticles by an organic ligand shell (oleic acid and oleylamine). CoO nanoparticles were easily prepared by this method, while the synthesis of the CoPt/CoO nanocomposites was

  14. Dynamic Response of Exchange Bias in Graphene Nanoribbons

    Science.gov (United States)

    2012-01-01

    subsequently reduced by N2H4, to afford the CCGNRs. A vibrating sample magnetometer ( VSM ) was used to measure the magnetization vs. magnetic field (M vs H...we did not attempt to test this KA model, and that forms the subject of our near future work on GNRs. Both the GNRs and NiFe/IrMn systems are

  15. Optimism Bias in Fans and Sports Reporters.

    Science.gov (United States)

    Love, Bradley C; Kopeć, Łukasz; Guest, Olivia

    2015-01-01

    People are optimistic about their prospects relative to others. However, existing studies can be difficult to interpret because outcomes are not zero-sum. For example, one person avoiding cancer does not necessitate that another person develops cancer. Ideally, optimism bias would be evaluated within a closed formal system to establish with certainty the extent of the bias and the associated environmental factors, such that optimism bias is demonstrated when a population is internally inconsistent. Accordingly, we asked NFL fans to predict how many games teams they liked and disliked would win in the 2015 season. Fans, like ESPN reporters assigned to cover a team, were overly optimistic about their team's prospects. The opposite pattern was found for teams that fans disliked. Optimism may flourish because year-to-year team results are marked by auto-correlation and regression to the group mean (i.e., good teams stay good, but bad teams improve).

  16. Optimism Bias in Fans and Sports Reporters

    Science.gov (United States)

    Love, Bradley C.

    2015-01-01

    People are optimistic about their prospects relative to others. However, existing studies can be difficult to interpret because outcomes are not zero-sum. For example, one person avoiding cancer does not necessitate that another person develops cancer. Ideally, optimism bias would be evaluated within a closed formal system to establish with certainty the extent of the bias and the associated environmental factors, such that optimism bias is demonstrated when a population is internally inconsistent. Accordingly, we asked NFL fans to predict how many games teams they liked and disliked would win in the 2015 season. Fans, like ESPN reporters assigned to cover a team, were overly optimistic about their team’s prospects. The opposite pattern was found for teams that fans disliked. Optimism may flourish because year-to-year team results are marked by auto-correlation and regression to the group mean (i.e., good teams stay good, but bad teams improve). PMID:26352146

  17. Hydrogen exchange

    DEFF Research Database (Denmark)

    Jensen, Pernille Foged; Rand, Kasper Dyrberg

    2016-01-01

    Hydrogen exchange (HX) monitored by mass spectrometry (MS) is a powerful analytical method for investigation of protein conformation and dynamics. HX-MS monitors isotopic exchange of hydrogen in protein backbone amides and thus serves as a sensitive method for probing protein conformation...... and dynamics along the entire protein backbone. This chapter describes the exchange of backbone amide hydrogen which is highly quenchable as it is strongly dependent on the pH and temperature. The HX rates of backbone amide hydrogen are sensitive and very useful probes of protein conformation......, as they are distributed along the polypeptide backbone and form the fundamental hydrogen-bonding networks of basic secondary structure. The effect of pressure on HX in unstructured polypeptides (poly-dl-lysine and oxidatively unfolded ribonuclease A) and native folded proteins (lysozyme and ribonuclease A) was evaluated...

  18. Heat exchangers

    International Nuclear Information System (INIS)

    1975-01-01

    The tubes of a heat exchanger tube bank have a portion thereof formed in the shape of a helix, of effective radius equal to the tube radius and the space between two adjacent tubes, to tangentially contact the straight sections of the tubes immediately adjacent thereto and thereby provide support, maintain the spacing and account for differential thermal expansion thereof

  19. Heat exchanger

    International Nuclear Information System (INIS)

    Wolowodiuk, W.

    1976-01-01

    A heat exchanger of the straight tube type is described in which different rates of thermal expansion between the straight tubes and the supply pipes furnishing fluid to those tubes do not result in tube failures. The supply pipes each contain a section which is of helical configuration

  20. Exchange Options

    NARCIS (Netherlands)

    Jamshidian, F.

    2007-01-01

    The contract is described and market examples given. Essential theoretical developments are introduced and cited chronologically. The principles and techniques of hedging and unique pricing are illustrated for the two simplest nontrivial examples: the classical Black-Scholes/Merton/Margrabe exchange

  1. Test Bias and the Elimination of Racism

    Science.gov (United States)

    Sedlacek, William E.

    1977-01-01

    Three types of test bias are discussed: content bias, atmosphere bias, and use bias. Use bias is considered the most important. Tests reflect the bias in society, and eliminating test bias means eliminating racism and sexism in society. A six-stage model to eliminate racism and sexism is presented. (Author)

  2. Ion exchange equilibrium constants

    CERN Document Server

    Marcus, Y

    2013-01-01

    Ion Exchange Equilibrium Constants focuses on the test-compilation of equilibrium constants for ion exchange reactions. The book first underscores the scope of the compilation, equilibrium constants, symbols used, and arrangement of the table. The manuscript then presents the table of equilibrium constants, including polystyrene sulfonate cation exchanger, polyacrylate cation exchanger, polymethacrylate cation exchanger, polysterene phosphate cation exchanger, and zirconium phosphate cation exchanger. The text highlights zirconium oxide anion exchanger, zeolite type 13Y cation exchanger, and

  3. Heat exchanger

    International Nuclear Information System (INIS)

    Bennett, J.C.

    1975-01-01

    A heat exchanger such as forms, for example, part of a power steam boiler is made up of a number of tubes that may be arranged in many different ways, and it is necessary that the tubes be properly supported. The means by which the tubes are secured must be as simple as possible so as to facilitate construction and must be able to continue to function effectively under the varying operating conditions to which the heat exchanger is subject. The arrangement described is designed to meet these requirements, in an improved way. The tubes are secured to a member extending past several tubes and abutment means are provided. At least some of the abutment means comprise two abutment pieces and a wedge secured to the supporting member, that acts on these pieces to maintain the engagement. (U.K.)

  4. Collisional effects on ion energy and angular distributions incident on RF-biased electrodes

    International Nuclear Information System (INIS)

    Qiu Huatan; Wang Younian; Ma Tengcai

    2002-01-01

    Taking into account elastic collisions and charge-exchange collisions between ions and neutral particles, the authors established a self-consistent model describing the dynamics of radio-frequency (RF) sheath driven by a sinusoidal current source, and also, using the Monte-Carlo Method, simulated energy and angle distributions of ions bombarding on RF-biased substrates. It has been shown from numerical results that as increasing the discharge pressure, bimodal-peaks distributions for the ion energy become gradually a single-peak distribution, and low-energy ions increase. The authors also found that the angle distribution of ions is narrow and almost do not change with increasing the discharge pressure

  5. Properties of Foreign Exchange Risk Premiums

    DEFF Research Database (Denmark)

    Sarno, Lucio; Schneider, Paul; Wagner, Christian

    2012-01-01

    We study the properties of foreign exchange risk premiums that can explain the forward bias puzzle, defined as the tendency of high-interest rate currencies to appreciate rather than depreciate. These risk premiums arise endogenously from the no-arbitrage condition relating the term structure...

  6. Photoconductivity of biased graphene

    Science.gov (United States)

    Freitag, Marcus

    2013-03-01

    The origin of photosensitivity of graphene devices has been attributed to either thermoelectric, photovoltaic, or bolometric effects. Here we report on the intrinsic photoresponse of electrically biased, but otherwise homogeneous single-layer graphene. In this simple, yet unstudied experimental condition, the photocurrent shows polarity reversal, as it alternates between two of these effects while sweeping the electronic potential. Near the Dirac point, the photovoltaic effect dominates, and the photocurrent adds to the transport current. Away from the Dirac point, the bolometric effect dominates, and reduces the transport current. Magnitude and polarity of the photocurrent allow us to infer the hot carrier and phonon temperatures under light illumination. The electron temperature is found to be an order of magnitude higher than the phonon temperature, shedding light on energy loss pathways other than via intrinsic graphene phonons. (M. Freitag et al., Nature Photonics, accepted for publication (2012).)

  7. Biased Monte Carlo optimization: the basic approach

    International Nuclear Information System (INIS)

    Campioni, Luca; Scardovelli, Ruben; Vestrucci, Paolo

    2005-01-01

    It is well-known that the Monte Carlo method is very successful in tackling several kinds of system simulations. It often happens that one has to deal with rare events, and the use of a variance reduction technique is almost mandatory, in order to have Monte Carlo efficient applications. The main issue associated with variance reduction techniques is related to the choice of the value of the biasing parameter. Actually, this task is typically left to the experience of the Monte Carlo user, who has to make many attempts before achieving an advantageous biasing. A valuable result is provided: a methodology and a practical rule addressed to establish an a priori guidance for the choice of the optimal value of the biasing parameter. This result, which has been obtained for a single component system, has the notable property of being valid for any multicomponent system. In particular, in this paper, the exponential and the uniform biases of exponentially distributed phenomena are investigated thoroughly

  8. Bias modification training can alter approach bias and chocolate consumption.

    Science.gov (United States)

    Schumacher, Sophie E; Kemps, Eva; Tiggemann, Marika

    2016-01-01

    Recent evidence has demonstrated that bias modification training has potential to reduce cognitive biases for attractive targets and affect health behaviours. The present study investigated whether cognitive bias modification training could be applied to reduce approach bias for chocolate and affect subsequent chocolate consumption. A sample of 120 women (18-27 years) were randomly assigned to an approach-chocolate condition or avoid-chocolate condition, in which they were trained to approach or avoid pictorial chocolate stimuli, respectively. Training had the predicted effect on approach bias, such that participants trained to approach chocolate demonstrated an increased approach bias to chocolate stimuli whereas participants trained to avoid such stimuli showed a reduced bias. Further, participants trained to avoid chocolate ate significantly less of a chocolate muffin in a subsequent taste test than participants trained to approach chocolate. Theoretically, results provide support for the dual process model's conceptualisation of consumption as being driven by implicit processes such as approach bias. In practice, approach bias modification may be a useful component of interventions designed to curb the consumption of unhealthy foods. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Exchanging information

    International Nuclear Information System (INIS)

    1971-01-01

    The Agency has a statutory mandate to foster 'the exchange of scientific and technical information on the peaceful uses of atomic energy'. The prime responsibility for this work within the Agency lies with the Division of Scientific and Technical Information, a part of the Department of Technical Operations. The Division accomplishes its task by holding conferences and symposia (Scientific Conferences Section), through the Agency Library, by publishing scientific journals, and through the International Nuclear Information System (INIS). The Computer Section of the Division, which offers services to the Agency as a whole, provides resources for the automation of data storage and retrieval. (author)

  10. CULTURAL BIAS IN LANGUAGE TESTING

    OpenAIRE

    Patrisius Istiarto Djiwandono

    2006-01-01

    Abstract: An issue that has recently been gaining more attention in the domain of language testing is item bias. Defined as the characteristic of an item which causes learners of the same abilities but of different social groups to perform differently, the bias can be present as gender, ethnic, religious, social class, or cultural bias. The paper brings up a discussion in this area of concern by starting off from the concept of culture. It then explains what cultural bias is, how it manifests...

  11. Bias in clinical intervention research

    DEFF Research Database (Denmark)

    Gluud, Lise Lotte

    2006-01-01

    Research on bias in clinical trials may help identify some of the reasons why investigators sometimes reach the wrong conclusions about intervention effects. Several quality components for the assessment of bias control have been suggested, but although they seem intrinsically valid, empirical...... evidence is needed to evaluate their effects on the extent and direction of bias. This narrative review summarizes the findings of methodological studies on the influence of bias in clinical trials. A number of methodological studies suggest that lack of adequate randomization in published trial reports...

  12. Information environment, behavioral biases, and home bias in analysts’ recommendations

    DEFF Research Database (Denmark)

    Farooq, Omar; Taouss, Mohammed

    2012-01-01

    Can information environment of a firm explain home bias in analysts’ recommendations? Can the extent of agency problems explain optimism difference between foreign and local analysts? This paper answers these questions by documenting the effect of information environment on home bias in analysts’...

  13. Permanent magnet flux-biased magnetic actuator with flux feedback

    Science.gov (United States)

    Groom, Nelson J. (Inventor)

    1991-01-01

    The invention is a permanent magnet flux-biased magnetic actuator with flux feedback for adjustably suspending an element on a single axis. The magnetic actuator includes a pair of opposing electromagnets and provides bi-directional forces along the single axis to the suspended element. Permanent magnets in flux feedback loops from the opposing electromagnets establish a reference permanent magnet flux-bias to linearize the force characteristics of the electromagnets to extend the linear range of the actuator without the need for continuous bias currents in the electromagnets.

  14. Biased ligands: pathway validation for novel GPCR therapeutics.

    Science.gov (United States)

    Rominger, David H; Cowan, Conrad L; Gowen-MacDonald, William; Violin, Jonathan D

    2014-06-01

    G protein-coupled receptors (GPCRs), in recent years, have been shown to signal via multiple distinct pathways. Furthermore, biased ligands for some receptors can differentially stimulate or inhibit these pathways versus unbiased endogenous ligands or drugs. Biased ligands can be used to gain a deeper understanding of the molecular targets and cellular responses associated with a GPCR, and may be developed into therapeutics with improved efficacy, safety and/or tolerability. Here we review examples and approaches to pathway validation that establish the relevance and therapeutic potential of distinct pathways that can be selectively activated or blocked by biased ligands. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. Segmented heat exchanger

    Science.gov (United States)

    Baldwin, Darryl Dean; Willi, Martin Leo; Fiveland, Scott Byron; Timmons, Kristine Ann

    2010-12-14

    A segmented heat exchanger system for transferring heat energy from an exhaust fluid to a working fluid. The heat exchanger system may include a first heat exchanger for receiving incoming working fluid and the exhaust fluid. The working fluid and exhaust fluid may travel through at least a portion of the first heat exchanger in a parallel flow configuration. In addition, the heat exchanger system may include a second heat exchanger for receiving working fluid from the first heat exchanger and exhaust fluid from a third heat exchanger. The working fluid and exhaust fluid may travel through at least a portion of the second heat exchanger in a counter flow configuration. Furthermore, the heat exchanger system may include a third heat exchanger for receiving working fluid from the second heat exchanger and exhaust fluid from the first heat exchanger. The working fluid and exhaust fluid may travel through at least a portion of the third heat exchanger in a parallel flow configuration.

  16. Knowledge Exchange with Sistema Scotland

    Science.gov (United States)

    Allan, Julie; Moran, Nikki; Duffy, Celia; Loening, Gica

    2010-01-01

    This paper reports on a knowledge exchange project, funded by the Scottish Funding Council and undertaken by a group of researchers from three higher education institutions in Scotland and the project partner, Sistema Scotland. This newly established charity is attempting to implement a major programme of social change, developed in Venezuela,…

  17. Heuristic Biases in Mathematical Reasoning

    Science.gov (United States)

    Inglis, Matthew; Simpson, Adrian

    2005-01-01

    In this paper we briefly describe the dual process account of reasoning, and explain the role of heuristic biases in human thought. Concentrating on the so-called matching bias effect, we describe a piece of research that indicates a correlation between success at advanced level mathematics and an ability to override innate and misleading…

  18. Hidden multidimensional social structure modeling applied to biased social perception

    Science.gov (United States)

    Maletić, Slobodan; Zhao, Yi

    2018-02-01

    Intricacies of the structure of social relations are realized by representing a collection of overlapping opinions as a simplicial complex, thus building latent multidimensional structures, through which agents are, virtually, moving as they exchange opinions. The influence of opinion space structure on the distribution of opinions is demonstrated by modeling consensus phenomena when the opinion exchange between individuals may be affected by the false consensus effect. The results indicate that in the cases with and without bias, the road toward consensus is influenced by the structure of multidimensional space of opinions, and in the biased case, complete consensus is achieved. The applications of proposed modeling framework can easily be generalized, as they transcend opinion formation modeling.

  19. Large-scale galaxy bias

    Science.gov (United States)

    Jeong, Donghui; Desjacques, Vincent; Schmidt, Fabian

    2018-01-01

    Here, we briefly introduce the key results of the recent review (arXiv:1611.09787), whose abstract is as following. This review presents a comprehensive overview of galaxy bias, that is, the statistical relation between the distribution of galaxies and matter. We focus on large scales where cosmic density fields are quasi-linear. On these scales, the clustering of galaxies can be described by a perturbative bias expansion, and the complicated physics of galaxy formation is absorbed by a finite set of coefficients of the expansion, called bias parameters. The review begins with a detailed derivation of this very important result, which forms the basis of the rigorous perturbative description of galaxy clustering, under the assumptions of General Relativity and Gaussian, adiabatic initial conditions. Key components of the bias expansion are all leading local gravitational observables, which include the matter density but also tidal fields and their time derivatives. We hence expand the definition of local bias to encompass all these contributions. This derivation is followed by a presentation of the peak-background split in its general form, which elucidates the physical meaning of the bias parameters, and a detailed description of the connection between bias parameters and galaxy (or halo) statistics. We then review the excursion set formalism and peak theory which provide predictions for the values of the bias parameters. In the remainder of the review, we consider the generalizations of galaxy bias required in the presence of various types of cosmological physics that go beyond pressureless matter with adiabatic, Gaussian initial conditions: primordial non-Gaussianity, massive neutrinos, baryon-CDM isocurvature perturbations, dark energy, and modified gravity. Finally, we discuss how the description of galaxy bias in the galaxies' rest frame is related to clustering statistics measured from the observed angular positions and redshifts in actual galaxy catalogs.

  20. Large-scale galaxy bias

    Science.gov (United States)

    Desjacques, Vincent; Jeong, Donghui; Schmidt, Fabian

    2018-02-01

    This review presents a comprehensive overview of galaxy bias, that is, the statistical relation between the distribution of galaxies and matter. We focus on large scales where cosmic density fields are quasi-linear. On these scales, the clustering of galaxies can be described by a perturbative bias expansion, and the complicated physics of galaxy formation is absorbed by a finite set of coefficients of the expansion, called bias parameters. The review begins with a detailed derivation of this very important result, which forms the basis of the rigorous perturbative description of galaxy clustering, under the assumptions of General Relativity and Gaussian, adiabatic initial conditions. Key components of the bias expansion are all leading local gravitational observables, which include the matter density but also tidal fields and their time derivatives. We hence expand the definition of local bias to encompass all these contributions. This derivation is followed by a presentation of the peak-background split in its general form, which elucidates the physical meaning of the bias parameters, and a detailed description of the connection between bias parameters and galaxy statistics. We then review the excursion-set formalism and peak theory which provide predictions for the values of the bias parameters. In the remainder of the review, we consider the generalizations of galaxy bias required in the presence of various types of cosmological physics that go beyond pressureless matter with adiabatic, Gaussian initial conditions: primordial non-Gaussianity, massive neutrinos, baryon-CDM isocurvature perturbations, dark energy, and modified gravity. Finally, we discuss how the description of galaxy bias in the galaxies' rest frame is related to clustering statistics measured from the observed angular positions and redshifts in actual galaxy catalogs.

  1. The Effect of Monetary Policy on Exchange Rates : How to Solve the Puzzles

    NARCIS (Netherlands)

    Kumah, F.Y.

    1996-01-01

    Recent empirical research on the effects of monetary policy shocks on exchange rate fluctuations have encountered the exchange rate puzzle and th e forward discount bias puzzle.The exchange rate puzzle is the tendency of the domestic currency (of non-US G-7 countries) to depreciate against the US

  2. Question format shifts bias away from the emphasised response in tests of recognition memory.

    Science.gov (United States)

    Mill, Ravi D; O'Connor, Akira R

    2014-11-01

    The question asked to interrogate memory has potential to influence response bias at retrieval, yet has not been systematically investigated. According to framing effects in the field of eyewitness testimony, retrieval cueing effects in cognitive psychology and the acquiescence bias in questionnaire responding, the question should establish a confirmatory bias. Conversely, according to findings from the rewarded decision-making literature involving mixed incentives, the question should establish a disconfirmatory bias. Across three experiments (ns=90 [online], 29 [laboratory] and 29 [laboratory]) we demonstrate a disconfirmatory bias - "old?" decreased old responding. This bias is underpinned by a goal-driven mechanism wherein participants seek to maximise emphasised response accuracy at the expense of frequency. Moreover, we demonstrate that disconfirmatory biases can be generated without explicit reference to the goal state. We conclude that subtle aspects of the test environment influence retrieval to a greater extent than has been previously considered. Copyright © 2014 Elsevier Inc. All rights reserved.

  3. Spin Quantum Tunneling via Entangled States in a Dimer of Exchange-Coupled Single-Molecule Magnets

    Science.gov (United States)

    Tiron, R.; Wernsdorfer, W.; Foguet-Albiol, D.; Aliaga-Alcalde, N.; Christou, G.

    2003-11-01

    A new family of supramolecular, antiferromagnetically exchange-coupled dimers of single-molecule magnets (SMMs) has recently been reported. Each SMM acts as a bias on its neighbor, shifting the quantum tunneling resonances of the individual SMMs. Hysteresis loop measurements on a single crystal of SMM dimers have now established quantum tunneling of the magnetization via entangled states of the dimer. This shows that the dimer really does behave as a quantum mechanically coupled dimer, and also allows the measurement of the longitudinal and transverse superexchange coupling constants.

  4. Securities and Exchange Commission Semiannual Regulatory Agenda

    Science.gov (United States)

    2010-12-20

    ... Agency Contact: Ira Brandriss, Division of Trading and Markets, Securities and Exchange Commission, 100 F... require the establishment of book- entry accounts in connection with reorganization events and would give...

  5. CGH Short Term Scientist Exchange Program (STSEP)

    Science.gov (United States)

    STSEP promotes collaborative research between established U.S. and foreign scientists from low, middle, and upper-middle income countries (LMICs) by supporting, in part, exchange visits of cancer researchers between U.S. and foreign laboratories.

  6. Steady-State Density Functional Theory for Finite Bias Conductances.

    Science.gov (United States)

    Stefanucci, G; Kurth, S

    2015-12-09

    In the framework of density functional theory, a formalism to describe electronic transport in the steady state is proposed which uses the density on the junction and the steady current as basic variables. We prove that, in a finite window around zero bias, there is a one-to-one map between the basic variables and both local potential on as well as bias across the junction. The resulting Kohn-Sham system features two exchange-correlation (xc) potentials, a local xc potential, and an xc contribution to the bias. For weakly coupled junctions the xc potentials exhibit steps in the density-current plane which are shown to be crucial to describe the Coulomb blockade diamonds. At small currents these steps emerge as the equilibrium xc discontinuity bifurcates. The formalism is applied to a model benzene junction, finding perfect agreement with the orthodox theory of Coulomb blockade.

  7. Confirmation biases in selective exposure to political online information : Source bias vs. content bias

    NARCIS (Netherlands)

    Westerwick, Axel; Johnson, Benjamin K.; Knobloch-Westerwick, Silvia

    2017-01-01

    The present work examines the role of source vs. content cues for the confirmation bias, in which recipients spend more time with content aligning with preexisting attitudes. In addition to testing how both source and content cues facilitate this biased pattern of selective exposure, the study

  8. Cognitive bias in forensic anthropology: visual assessment of skeletal remains is susceptible to confirmation bias.

    Science.gov (United States)

    Nakhaeizadeh, Sherry; Dror, Itiel E; Morgan, Ruth M

    2014-05-01

    An experimental study was designed to examine cognitive biases within forensic anthropological non-metric methods in assessing sex, ancestry and age at death. To investigate examiner interpretation, forty-one non-novice participants were semi randomly divided into three groups. Prior to conducting the assessment of the skeletal remains, two of the groups were given different extraneous contextual information regarding the sex, ancestry and age at death of the individual. The third group acted as a control group with no extraneous contextual information. The experiment was designed to investigate if the interpretation and conclusions of the skeletal remains would differ amongst participants within the three groups, and to assess whether the examiners would confirm or disagree with the given extraneous context when establishing a biological profile. The results revealed a significant biasing effect within the three groups, demonstrating a strong confirmation bias in the assessment of sex, ancestry and age at death. In assessment of sex, 31% of the participants in the control group concluded that the skeleton remains were male. In contrast, in the group that received contextual information that the remains were male, 72% concluded that the remains were male, and in the participant group where the context was that the remains were of a female, 0% of the participants concluded that the remains were male. Comparable results showing bias were found in assessing ancestry and age at death. These data demonstrate that cognitive bias can impact forensic anthropological non-metric methods on skeletal remains and affects the interpretation and conclusions of the forensic scientists. This empirical study is a step in establishing an evidence base approach for dealing with cognitive issues in forensic anthropological assessments, so as to enhance this valuable forensic science discipline. Copyright © 2013 Forensic Science Society. Published by Elsevier Ireland Ltd. All rights

  9. Cognitive Biases Questionnaire for psychosis.

    Science.gov (United States)

    Peters, Emmanuelle R; Moritz, Steffen; Schwannauer, Matthias; Wiseman, Zoe; Greenwood, Kathryn E; Scott, Jan; Beck, Aaron T; Donaldson, Catherine; Hagen, Roger; Ross, Kerry; Veckenstedt, Ruth; Ison, Rebecca; Williams, Sally; Kuipers, Elizabeth; Garety, Philippa A

    2014-03-01

    The Cognitive Biases Questionnaire for psychosis (CBQp) was developed to capture 5 cognitive distortions (jumping to conclusions, intentionalising, catastrophising, emotional reasoning, and dichotomous thinking), which are considered important for the pathogenesis of psychosis. Vignettes were adapted from the Cognitive Style Test (CST),(1) relating to "Anomalous Perceptions" and "Threatening Events" themes. Scale structure, reliability, and validity were investigated in a psychosis group, and CBQp scores were compared with those of depressed and healthy control samples. The CBQp showed good internal consistency and test-retest reliability. The 5 biases were not independent, with a 2-related factor scale providing the best fit. This structure suggests that the CBQp assesses a general thinking bias rather than distinct cognitive errors, while Anomalous Perception and Threatening Events theme scores can be used separately. Total CBQp scores showed good convergent validity with the CST, but individual biases were not related to existing tasks purporting to assess similar reasoning biases. Psychotic and depressed populations scored higher than healthy controls, and symptomatic psychosis patients scored higher than their nonsymptomatic counterparts, with modest relationships between CBQp scores and symptom severity once emotional disorders were partialled out. Anomalous Perception theme and Intentionalising bias scores showed some specificity to psychosis. Overall, the CBQp has good psychometric properties, although it is likely that it measures a different construct to existing tasks, tentatively suggested to represent a bias of interpretation rather than reasoning, judgment or decision-making processes. It is a potentially useful tool in both research and clinical arenas.

  10. Cognitive Bias in Systems Verification

    Science.gov (United States)

    Larson, Steve

    2012-01-01

    Working definition of cognitive bias: Patterns by which information is sought and interpreted that can lead to systematic errors in decisions. Cognitive bias is used in diverse fields: Economics, Politics, Intelligence, Marketing, to name a few. Attempts to ground cognitive science in physical characteristics of the cognitive apparatus exceed our knowledge. Studies based on correlations; strict cause and effect is difficult to pinpoint. Effects cited in the paper and discussed here have been replicated many times over, and appear sound. Many biases have been described, but it is still unclear whether they are all distinct. There may only be a handful of fundamental biases, which manifest in various ways. Bias can effect system verification in many ways . Overconfidence -> Questionable decisions to deploy. Availability -> Inability to conceive critical tests. Representativeness -> Overinterpretation of results. Positive Test Strategies -> Confirmation bias. Debiasing at individual level very difficult. The potential effect of bias on the verification process can be managed, but not eliminated. Worth considering at key points in the process.

  11. Administrative bias in South Africa

    Directory of Open Access Journals (Sweden)

    E S Nwauche

    2005-01-01

    Full Text Available This article reviews the interpretation of section 6(2(aii of the Promotion of Administrative Justice Act which makes an administrator “biased or reasonably suspected of bias” a ground of judicial review. In this regard, the paper reviews the determination of administrative bias in South Africa especially highlighting the concept of institutional bias. The paper notes that inspite of the formulation of the bias ground of review the test for administrative bias is the reasonable apprehension test laid down in the case of President of South Africa v South African Rugby Football Union(2 which on close examination is not the same thing. Accordingly the paper urges an alternative interpretation that is based on the reasonable suspicion test enunciated in BTR Industries South Africa (Pty Ltd v Metal and Allied Workers Union and R v Roberts. Within this context, the paper constructs a model for interpreting the bias ground of review that combines the reasonable suspicion test as interpreted in BTR Industries and R v Roberts, the possibility of the waiver of administrative bias, the curative mechanism of administrative appeal as well as some level of judicial review exemplified by the jurisprudence of article 6(1 of the European Convention of Human Rights, especially in the light of the contemplation of the South African Magistrate Court as a jurisdictional route of judicial review.

  12. Gender bias in academic recruitment

    DEFF Research Database (Denmark)

    Abramo, Giovanni; D’Angelo, Ciriaco Andrea; Rosati, Francesco

    2016-01-01

    It is well known that women are underrepresented in the academic systems of many countries. Gender discrimination is one of the factors that could contribute to this phenomenon. This study considers a recent national academic recruitment campaign in Italy, examining whether women are subject...... to more or less bias than men. The findings show that no gender-related differences occur among the candidates who benefit from positive bias, while among those candidates affected by negative bias, the incidence of women is lower than that of men. Among the factors that determine success in a competition...

  13. Heuristics and bias in homeopathy.

    Science.gov (United States)

    Souter, K

    2006-10-01

    The practice of Homeopathy ought to be strictly logical. In the Organon Samuel Hahnemann gives the impression that the unprejudiced observer should be able to follow an algorithmic route to the simillimum in every case. Judgement and Decision Research, however, indicates that when people grapple with complex systems like homeopathy they are more likely to use heuristics or empirical rules to help them reach a solution. Thus Hahnemann's concept of the unprejudiced observer is virtually impossible to attain. There is inevitable bias in both case-taking and remedy selection. Understanding the types of bias may enable the practitioner to reduce his/her own bias.

  14. Deuterium exchange in sesamol

    International Nuclear Information System (INIS)

    Hill, R.K.; Vaidya, N.A.; Morton, G.H.

    1982-01-01

    Trifluoroacetic acid-catalyzed exchange of sesamol in 2 H 2 O results in rapid exchange of H-6 and slower exchange of H-2. The deuterium atoms introduced are retained during conversion to the methyl and allyl ethers. (author)

  15. Inflationary trispectrum from graviton exchange

    DEFF Research Database (Denmark)

    Seery, David; Sloth, Martin Snoager; Vernizzi, Filippo

    2009-01-01

    We compute the connected four-point correlation function of the primordial curvature perturbation generated during inflation with standard kinetic terms, where the correlation is established via exchange of a graviton between two pairs of scalar fluctuations. Any such correlation yields a contrib...... where the momentum of the graviton which is exchanged becomes much smaller than the external momenta. We conclude that the total non-linearity parameter generated by single-field models of slow-roll inflation is at maximum tauNL ~ r....

  16. Bilingual comparison of Mandarin and English cognitive bias tasks.

    Science.gov (United States)

    Smith, Louise; Leung, Wing Gi; Crane, Bryony; Parkinson, Brian; Toulopoulou, Timothea; Yiend, Jenny

    2018-02-01

    Most research into cognitive biases has used Western samples, despite potential East-West socio-cultural differences. One reason is the lack of appropriate measures for non-Westerners. This study is about cross-linguistic equivalence which needs to be established before assessing cross-cultural differences in future research. We developed parallel Mandarin and English measures of interpretation bias and attention bias using back-translation and decentering procedures. We assessed task equivalence by administering both sets of measures to 47 bilingual Mandarin-English speakers. Interpretation bias measurement was similar and reliable across language versions, confirming suitability of the Mandarin versions for future cross-cultural research. By contrast, scores on attention bias tasks did not intercorrelate reliably, suggesting that nonverbal stimuli such as pictures or facial expressions of emotion might present better prospects for cross-cultural comparison. The development of the first set of equivalent measures of interpretation bias in an Eastern language paves the way for future research investigating East-West differences in biased cognition.

  17. Edge biasing in the WEGA stellarator

    International Nuclear Information System (INIS)

    Lischtschenko, Oliver

    2009-01-01

    The WEGA stellarator is used to confine low temperature, overdense (densities exceeding the cut-off density of the heating wave) plasmas by magnetic fields in the range of B=50-500 mT. Microwave heating systems are used to ignite gas discharges using hydrogen, helium, neon or argon as working gases. The produced plasmas have been analyzed using Langmuir and emissive probes, a single-channel interferometer and ultra-high resolution Doppler spectroscopy. For a typical argon discharge in the low field operation, B=56 mT, the maximum electron density is n e ∝10 18 m -3 with temperatures in the range of T=4-12 eV. The plasma parameters are determined by using Langmuir probes and are cross-checked with interferometry. It is demonstrated within this work that the joint use of emissive probes and ultra-high resolution Doppler spectroscopy allows a precise measurement of the radial electric field. The focus of this work is on demonstrating the ability to modify the existing radial electric field in a plasma by using the biasing probe. This work commences with a basic approach and first establishes the diagnostic tools in a well-known discharge. Then the perturbation caused by the biasing probe is assessed. Following the characterization of the unperturbed plasmas, plasma states altered by the operation of the energized biasing probe are characterized. During biasing the plasma two different stable plasma states have been found. The two observed plasma states differ in plasma parameter profiles, such as density, temperature, electric field and confined energy. (orig.)

  18. Minimum Bias Trigger in ATLAS

    CERN Document Server

    Kwee, R E; The ATLAS collaboration

    2010-01-01

    Since the restart of the LHC in November 2009, ATLAS has collected inelastic pp-collisions to perform first measurements on charged particle densities. These measurements will help to constrain various models describing phenomenologically soft parton interactions. Understanding the trigger efficiencies for different event types are therefore crucial to minimize any possible bias in the event selection. ATLAS uses two main minimum bias triggers, featuring complementary detector components and trigger levels. While a hardware based first trigger level situated in the forward regions with 2.09 < |eta| < 3.8 has been proven to select pp-collisions very efficiently, the Inner Detector based minimum bias trigger uses a random seed on filled bunches and central tracking detectors for the event selection. Both triggers were essential for the analysis of kinematic spectra of charged particles. Their performance and trigger efficiency measurements as well as studies on possible bias sources will be presen...

  19. A lateralized bias in mental imagery: evidence for representational pseudoneglect.

    Science.gov (United States)

    McGeorge, Peter; Beschin, Nicoletta; Colnaghi, Alessandra; Rusconi, Maria Luisa; Della Sala, Sergio

    2007-06-29

    One hundred right-handed healthy individuals were asked to imagine a familiar scene (the Piazza del Duomo, Milan) from two opposite viewpoints and report what they could see. For elements that should be visible from the participants' viewpoint, more elements were reported from the left side of the image than from the right, irrespective of view. These results establish that there is a lateralized bias in reporting the details in mental images--representational pseudoneglect. This bias is in the opposite direction and significantly smaller than the bias seen in individuals with representational neglect following right hemisphere damage. Representational pseudoneglect appears analogous to perceptual pseudoneglect and the two may share an underlying mechanism. The results are interpreted as indicating that pseudo-representational neglect arises as the result of a bias in the allocation of attention to the imagined scene.

  20. Totalization Data Exchange (TDEX)

    Data.gov (United States)

    Social Security Administration — The Totalization Data Exchange (TDEX) process is an exchange between SSA and its foreign country partners to identify deaths of beneficiaries residing abroad. The...

  1. Preferences, country bias, and international trade

    NARCIS (Netherlands)

    S. Roy (Santanu); J.M.A. Viaene (Jean-Marie)

    1998-01-01

    textabstractAnalyzes international trade where consumer preferences exhibit country bias. Why country biases arise; How trade can occur in the presence of country bias; Implication for the pattern of trade and specialization.

  2. The Selective Advantage of Synonymous Codon Usage Bias in Salmonella.

    Directory of Open Access Journals (Sweden)

    Gerrit Brandis

    2016-03-01

    Full Text Available The genetic code in mRNA is redundant, with 61 sense codons translated into 20 different amino acids. Individual amino acids are encoded by up to six different codons but within codon families some are used more frequently than others. This phenomenon is referred to as synonymous codon usage bias. The genomes of free-living unicellular organisms such as bacteria have an extreme codon usage bias and the degree of bias differs between genes within the same genome. The strong positive correlation between codon usage bias and gene expression levels in many microorganisms is attributed to selection for translational efficiency. However, this putative selective advantage has never been measured in bacteria and theoretical estimates vary widely. By systematically exchanging optimal codons for synonymous codons in the tuf genes we quantified the selective advantage of biased codon usage in highly expressed genes to be in the range 0.2-4.2 x 10-4 per codon per generation. These data quantify for the first time the potential for selection on synonymous codon choice to drive genome-wide sequence evolution in bacteria, and in particular to optimize the sequences of highly expressed genes. This quantification may have predictive applications in the design of synthetic genes and for heterologous gene expression in biotechnology.

  3. Reducing ongoing product design decision-making bias

    NARCIS (Netherlands)

    Antioco, M.; Moenaert, R.K.; Lindgreen, A.

    2008-01-01

    The objective of this exploratory study is to add to our understanding of ongoing product design decision-making to reduce eventual decision-making bias. Six research questions are formulated with the aim to establish if and how functional membership and informal patterns of communication within an

  4. Bias-corrected estimation of stable tail dependence function

    DEFF Research Database (Denmark)

    Beirlant, Jan; Escobar-Bach, Mikael; Goegebeur, Yuri

    2016-01-01

    We consider the estimation of the stable tail dependence function. We propose a bias-corrected estimator and we establish its asymptotic behaviour under suitable assumptions. The finite sample performance of the proposed estimator is evaluated by means of an extensive simulation study where...

  5. A New Technique for Demonstrating the Actor-Observer Bias

    Science.gov (United States)

    Gordon, Anne K.; Kaplar, Mary E.

    2002-01-01

    In this article we describe a new classroom exercise for introducing the actor-observer bias in social perception. We describe 2 experiments that compared our new technique (which involves resolving interpersonal dilemmas for oneself and another) with a previously established technique (judging the applicability of traits for oneself and another).…

  6. Exchange market pressure

    NARCIS (Netherlands)

    Jager, H.; Klaassen, F.; Durlauf, S.N.; Blume, L.E.

    2010-01-01

    Currencies can be under severe pressure in the foreign exchange market, but in a fixed (or managed) exchange rate regime that is not fully visible via the change in the exchange rate. Exchange market pressure (EMP) is a concept developed to nevertheless measure the pressure in such cases. This

  7. Assessing attentional biases with stuttering.

    Science.gov (United States)

    Lowe, Robyn; Menzies, Ross; Packman, Ann; O'Brian, Sue; Jones, Mark; Onslow, Mark

    2016-01-01

    Many adults who stutter presenting for speech treatment experience social anxiety disorder. The presence of mental health disorders in adults who stutter has been implicated in a failure to maintain speech treatment benefits. Contemporary theories of social anxiety disorder propose that the condition is maintained by negative cognitions and information processing biases. Consistent with cognitive theories, the probe detection task has shown that social anxiety is associated with an attentional bias to avoid social information. This information processing bias is suggested to be involved in maintaining anxiety. Evidence is emerging for information processing biases being involved with stuttering. This study investigated information processing in adults who stutter using the probe detection task. Information processing biases have been implicated in anxiety maintenance in social anxiety disorder and therefore may have implications for the assessment and treatment of stuttering. It was hypothesized that stuttering participants compared with control participants would display an attentional bias to avoid attending to social information. Twenty-three adults who stutter and 23 controls completed a probe detection task in which they were presented with pairs of photographs: a face displaying an emotional expression-positive, negative or neutral-and an everyday household object. All participants were subjected to a mild social threat induction being told they would speak to a small group of people on completion of the task. The stuttering group scored significantly higher than controls for trait anxiety, but did not differ from controls on measures of social anxiety. Non-socially anxious adults who stutter did not display an attentional bias to avoid looking at photographs of faces relative to everyday objects. Higher scores on trait anxiety were positively correlated with attention towards photographs of negative faces. Attentional biases as assessed by the probe

  8. Motion-Correlated Flow Distortion and Wave-Induced Biases in Air-Sea Flux Measurements From Ships

    Science.gov (United States)

    Prytherch, J.; Yelland, M. J.; Brooks, I. M.; Tupman, D. J.; Pascal, R. W.; Moat, B. I.; Norris, S. J.

    2016-02-01

    Direct measurements of the turbulent air-sea fluxes of momentum, heat, moisture and gases are often made using sensors mounted on ships. Ship-based turbulent wind measurements are corrected for platform motion using well established techniques, but biases at scales associated with wave and platform motion are often still apparent in the flux measurements. It has been uncertain whether this signal is due to time-varying distortion of the air flow over the platform, or to wind-wave interactions impacting the turbulence. Methods for removing such motion-scale biases from scalar measurements have previously been published but their application to momentum flux measurements remains controversial. Here we use eddy covariance momentum flux measurements obtained onboard RRS James Clark Ross as part of the Waves, Aerosol and Gas Exchange Study (WAGES), a programme of near-continuous measurements using the autonomous AutoFlux system (Yelland et al., 2009). Measurements were made in 2013 in locations throughout the North and South Atlantic, the Southern Ocean and the Arctic Ocean, at latitudes ranging from 62°S to 75°N. We show that the measured motion-scale bias has a dependence on the horizontal ship velocity, and that a correction for it reduces the dependence of the measured momentum flux on the orientation of the ship to the wind. We conclude that the bias is due to experimental error, and that time-varying motion-dependent flow distortion is the likely source. Yelland, M., Pascal, R., Taylor, P. and Moat, B.: AutoFlux: an autonomous system for the direct measurement of the air-sea fluxes of CO2, heat and momentum. J. Operation. Oceanogr., 15-23, doi:10.1080/1755876X.2009.11020105, 2009.

  9. A Model of Gravity Vector Measurement Noise for Estimating Accelerometer Bias in Gravity Disturbance Compensation.

    Science.gov (United States)

    Tie, Junbo; Cao, Juliang; Chang, Lubing; Cai, Shaokun; Wu, Meiping; Lian, Junxiang

    2018-03-16

    Compensation of gravity disturbance can improve the precision of inertial navigation, but the effect of compensation will decrease due to the accelerometer bias, and estimation of the accelerometer bias is a crucial issue in gravity disturbance compensation. This paper first investigates the effect of accelerometer bias on gravity disturbance compensation, and the situation in which the accelerometer bias should be estimated is established. The accelerometer bias is estimated from the gravity vector measurement, and a model of measurement noise in gravity vector measurement is built. Based on this model, accelerometer bias is separated from the gravity vector measurement error by the method of least squares. Horizontal gravity disturbances are calculated through EGM2008 spherical harmonic model to build the simulation scene, and the simulation results indicate that precise estimations of the accelerometer bias can be obtained with the proposed method.

  10. Hindsight bias in political elections.

    Science.gov (United States)

    Blank, Hartmut; Fischer, Volkhard; Erdfelder, Edgar

    2003-01-01

    Two studies on political hindsight bias were conducted on the occasions of the German parliament election in 1998 and the Nordrhein-Westfalen state parliament election in 2000. In both studies, participants predicted the percentage of votes for several political parties and recalled these predictions after the election. The observed hindsight effects were stronger than those found in any prior study on political elections (using percentage of votes as the dependent variable). We argue that the length of the retention interval between original judgement and recollection is mainly responsible for this difference. In our second study, we investigated possible artifacts in political hindsight biases using a control-group design where half of the participants recalled their predictions shortly before or after the election. Hindsight bias was preserved, reinforcing the results of earlier studies with non-control-group designs. Finally, we discuss the possibility that the hindsight experience (in political judgement and in general) actually consists of three different, partly independent components.

  11. News Consumption and Media Bias

    OpenAIRE

    Yi Xiang; Miklos Sarvary

    2007-01-01

    Bias in the market for news is well-documented. Recent research in economics explains the phenomenon by assuming that consumers want to read (watch) news that is consistent with their tastes or prior beliefs rather than the truth. The present paper builds on this idea but recognizes that (i) besides “biased” consumers, there are also “conscientious” consumers whose sole interest is in discovering the truth, and (ii) consistent with reality, media bias is constrained by the truth. These two fa...

  12. Biased limiter experiments on text

    International Nuclear Information System (INIS)

    Phillips, P.E.; Wootton, A.J.; Rowan, W.L.; Ritz, C.P.; Rhodes, T.L.; Bengtson, R.D.; Hodge, W.L.; Durst, R.D.; McCool, S.C.; Richards, B.; Gentle, K.W.; Schoch, P.; Forster, J.C.; Hickok, R.L.; Evans, T.E.

    1987-01-01

    Experiments using an electrically biased limiter have been performed on the Texas Experimental Tokamak (TEXT). A small movable limiter is inserted past the main poloidal ring limiter (which is electrically connected to the vacuum vessel) and biased at V Lim with respect to it. The floating potential, plasma potential and shear layer position can be controlled. With vertical strokeV Lim vertical stroke ≥ 50 V the plasma density increases. For V Lim Lim > 0 the results obtained are inconclusive. Variation of V Lim changes the electrostatic turbulence which may explain the observed total flux changes. (orig.)

  13. Unpacking the Evidence of Gender Bias

    Science.gov (United States)

    Fulmer, Connie L.

    2010-01-01

    The purpose of this study was to investigate gender bias in pre-service principals using the Gender-Leader Implicit Association Test. Analyses of student-learning narratives revealed how students made sense of gender bias (biased or not-biased) and how each reacted to evidence (surprised or not-surprised). Two implications were: (1) the need for…

  14. Without Bias: A Guidebook for Nondiscriminatory Communication.

    Science.gov (United States)

    Pickens, Judy E., Ed.; And Others

    This guidebook discusses ways to eliminate various types of discrimination from business communications. Separately authored chapters discuss eliminating racial and ethnic bias; eliminating sexual bias; achieving communication sensitive about handicaps of disabled persons; eliminating bias from visual media; eliminating bias from meetings,…

  15. Collection Development and the Psychology of Bias

    Science.gov (United States)

    Quinn, Brian

    2012-01-01

    The library literature addressing the role of bias in collection development emphasizes a philosophical approach. It is based on the notion that bias can be controlled by the conscious act of believing in certain values and adhering to a code of ethics. It largely ignores the psychological research on bias, which suggests that bias is a more…

  16. Measurement Bias Detection through Factor Analysis

    Science.gov (United States)

    Barendse, M. T.; Oort, F. J.; Werner, C. S.; Ligtvoet, R.; Schermelleh-Engel, K.

    2012-01-01

    Measurement bias is defined as a violation of measurement invariance, which can be investigated through multigroup factor analysis (MGFA), by testing across-group differences in intercepts (uniform bias) and factor loadings (nonuniform bias). Restricted factor analysis (RFA) can also be used to detect measurement bias. To also enable nonuniform…

  17. Perceptual memory drives learning of retinotopic biases for bistable stimuli.

    Directory of Open Access Journals (Sweden)

    Aidan Peter Murphy

    2014-02-01

    Full Text Available The visual system exploits past experience at multiple timescales to resolve perceptual ambiguity in the retinal image. For example, perception of a bistable stimulus can be biased towards one interpretation over another when preceded by a brief presentation of a disambiguated version of the stimulus (positive priming or through intermittent presentations of the ambiguous stimulus (stabilization. Similarly, prior presentations of unambiguous stimuli can be used to explicitly train a long-lasting association between a percept and a retinal location (perceptual association. These phenonema have typically been regarded as independent processes, with short-term biases attributed to perceptual memory and longer-term biases described as associative learning. Here we tested for interactions between these two forms of experience-dependent perceptual bias and demonstrate that short-term processes strongly influence long-term outcomes. We first demonstrate that the establishment of long-term perceptual contingencies does not require explicit training by unambiguous stimuli, but can arise spontaneously during the periodic presentation of brief, ambiguous stimuli. Using rotating Necker cube stimuli, we observed enduring, retinotopically specific perceptual biases that were expressed from the outset and remained stable for up to forty minutes, consistent with the known phenomenon of perceptual stabilization. Further, bias was undiminished after a break period of five minutes, but was readily reset by interposed periods of continuous, as opposed to periodic, ambiguous presentation. Taken together, the results demonstrate that perceptual biases can arise naturally and may principally reflect the brain’s tendency to favor recent perceptual interpretation at a given retinal location. Further, they suggest that an association between retinal location and perceptual state, rather than a physical stimulus, is sufficient to generate long-term biases in perceptual

  18. Establishment Registration & Device Listing

    Data.gov (United States)

    U.S. Department of Health & Human Services — This searchable database contains establishments (engaged in the manufacture, preparation, propagation, compounding, assembly, or processing of medical devices...

  19. Towards a theory of bias and equivalence

    OpenAIRE

    Vijver, Fons J.R. van de

    1998-01-01

    "Bias refers to the presence of nuisance factors in cross-cultural research. Three types of bias are distinguished, depending on whether the nuisance factor is located at the level of the construct (construct bias), the measurement instrument as a whole (method bias) or the items (item bias or differential item functioning). Equivalence refers to the measurement level characteristics that apply to cross-cultural score comparisons; three types of equivalence are defined: construct (identity of...

  20. Gender bias in teaching evaluations

    NARCIS (Netherlands)

    Mengel, Friederike; Sauermann, Jan; Zölitz, Ulf Zoelitz

    2017-01-01

    This paper provides new evidence on gender bias in teaching evaluations. We exploit a quasi-experimental dataset of 19,952 student evaluations of university faculty in a context where students are randomly allocated to female or male instructors. Despite the fact that neither students’ grades nor

  1. Ratio Bias and Policy Preferences

    DEFF Research Database (Denmark)

    Pedersen, Rasmus Tue

    2016-01-01

    Numbers permeate modern political communication. While current scholarship on framing effects has focused on the persuasive effects of words and arguments, this article shows that framing of numbers can also substantially affect policy preferences. Such effects are caused by ratio bias, which...

  2. Perception bias in route choice

    NARCIS (Netherlands)

    Vreeswijk, Jacob Dirk; Thomas, Tom; van Berkum, Eric C.; van Arem, Bart

    2014-01-01

    Travel time is probably one of the most studied attributes in route choice. Recently, perception of travel time received more attention as several studies have shown its importance in explaining route choice behavior. In particular, travel time estimates by travelers appear to be biased against non-

  3. Perception bias in route choice

    NARCIS (Netherlands)

    Vreeswijk, Jacob Dirk; Thomas, Tom; van Berkum, Eric C.; van Arem, Bart

    2014-01-01

    Travel time is probably one of the most studied attributes in route choice. Recently, perception of travel time received more attention as several studies have shown its importance in explaining route choice behavior. In particular, travel time estimates by travelers appear to be biased against

  4. Bias and Conflict: A Case for Logical Intuitions.

    Science.gov (United States)

    De Neys, Wim

    2012-01-01

    Human reasoning has been characterized as often biased, heuristic, and illogical. In this article, I consider recent findings establishing that, despite the widespread bias and logical errors, people at least implicitly detect that their heuristic response conflicts with traditional normative considerations. I propose that this conflict sensitivity calls for the postulation of logical and probabilistic knowledge that is intuitive and that is activated automatically when people engage in a reasoning task. I sketch the basic characteristics of these intuitions and point to implications for ongoing debates in the field. © Association for Psychological Science 2012.

  5. Laser gyros in system application with rate-bias technique

    Science.gov (United States)

    Bueschelberger, H. J.; Handrich, E.; Malthan, H.; Schmidt, G.

    The state of the art of the dithered laser gyro is briefly reviewed. It is noted that, despite the lock-in problem and the disadvantages of the dither mechanization used to date, the laser gyro has established itself in high-accuracy (better than 1 NM/h) strapdown navigation systems. This success can be attributed to such laser gyro advantages as digital output, the absence of fast-rotating parts, g insensitivity, high scalefactor accuracy, and high reliability. The rate bias concept is then examined, and the advantages of rate bias technology are discussed.

  6. What drives social in-group biases in face recognition memory? ERP evidence from the own-gender bias.

    OpenAIRE

    Wolff, N.; Kemter, K.; Schweinberger, S.R.; Wiese, H.

    2014-01-01

    It is well established that memory is more accurate for own-relative to other-race faces (own-race bias), which has been suggested to result from larger perceptual expertise for own-race faces. Previous studies also demonstrated better memory for own-relative to other-gender faces, which is less likely to result from differences in perceptual expertise, and rather may be related to social in-group vs out-group categorization. We examined neural correlates of the own-gender bias using event-re...

  7. KOREKSI BIAS BETA SAHAM DI BURSA EFEK INDONESIA PERIODE 2009-2012

    Directory of Open Access Journals (Sweden)

    Indah Saptorini

    2016-04-01

    Full Text Available This  study  aims  to  determine  whether  the  beta  value  of  shares  listed  on  the Indonesia Stock Exchange (BEI is a bias beta due to nonsynchronous trading activities.  There  are  310  companies  listed  on  the  Stock  Exchange  2009-2012 period  sampled  in  this  study.  The  bias  needs  to  be  corrected.  From  three methods employed : the Scholes and Williams (1977, the Dimson (1979, and the Fowler and Rorke (1983. Results of the analysis conclude that the shares on the Stock Exchange has a bias beta caused by not having a securities trading for  some  time.  This  resulted  in  the  calculation  of  IHSG  the  period  of  t  was biased because it uses the closing price of the period t-1.  In  this  study  bias  beta  correction  method  Scholes  and  Williams  (1977,  both one lag one lead and two lag two lead are better than the bias beta correction method Dimson (1979 and the bias beta correction method Fowler and Rorke (1983 because the value of beta Scholes and Williams after corrected close to one. Keywords : Nonsynchronous tradings, thin tradings, bias

  8. Laser Processed Heat Exchangers

    Data.gov (United States)

    National Aeronautics and Space Administration — The considerable mass of Heat Exchangers (HXs) and coldplates on spacecraft as well as the problematic coatings of the Condensing Heat Exchanger (CHX) are among the...

  9. Isotopically exchangeable phosphorus

    International Nuclear Information System (INIS)

    Barbaro, N.O.

    1984-01-01

    A critique revision of isotope dilution is presented. The concepts and use of exchangeable phosphorus, the phosphate adsorption, the kinetics of isotopic exchange and the equilibrium time in soils are discussed. (M.A.C.) [pt

  10. Procedures for Dealing with Optimism Bias in Transport Planning

    DEFF Research Database (Denmark)

    Flyvbjerg, Bent; Glenting, Carsten; Rønnest, Arne Kvist

    The UK Treasury (HM Treasury) has noted there is a demonstrated, systematic, tendency for project appraisers to be overly optimistic and that to redress this tendency appraisers should make explicit, empirically based adjustments to the estimates of a project's costs, benefits, and duration. HM...... of the document are to provide empirically based optimism bias up-lifts for selected reference classes of transport infrastructure projects and provide guidance on using the established uplifts to produce more realistic forecasts for the individual project's capital expenditures. Furthermore, the underlying...... causes and institutional context for optimism bias in British transport projects are discussed and some possibilities for reducing optimism bias in project preparation and decision-making are identified....

  11. Bias-reduced estimation of long memory stochastic volatility

    DEFF Research Database (Denmark)

    Frederiksen, Per; Nielsen, Morten Ørregaard

    We propose to use a variant of the local polynomial Whittle estimator to estimate the memory parameter in volatility for long memory stochastic volatility models with potential nonstation- arity in the volatility process. We show that the estimator is asymptotically normal and capable of obtaining...... bias reduction as well as a rate of convergence arbitrarily close to the parametric rate, n1=2. A Monte Carlo study is conducted to support the theoretical results, and an analysis of daily exchange rates demonstrates the empirical usefulness of the estimators....

  12. Jets in minimum bias physics

    International Nuclear Information System (INIS)

    Pancheri, G.; Srivastava, Y.

    1985-01-01

    Discussion was made on a phenomenological evidence to support the hypothesis that several new phenomena observed in low psub(t) physics are due to the presence of low-x QCD jets in minimum bias physics. The phenomena we examine are KNO scaling violations, growth of with multiplicity and rise of the non-single diffractive part of the total cross-section. We have discussed the importance of low-x hard parton scattering in minimum bias events and pointed out its connection to both KNO scaling violations as well as to the observed growth of with multiplicity in inclusive pion distributions. The contribution of these mini-jets to the total cross-section has been calculated and a model for the transverse energy distribution characterizing any event accompanied by jets has been presented. (author)

  13. Variable-bias coin tossing

    International Nuclear Information System (INIS)

    Colbeck, Roger; Kent, Adrian

    2006-01-01

    Alice is a charismatic quantum cryptographer who believes her parties are unmissable; Bob is a (relatively) glamorous string theorist who believes he is an indispensable guest. To prevent possibly traumatic collisions of self-perception and reality, their social code requires that decisions about invitation or acceptance be made via a cryptographically secure variable-bias coin toss (VBCT). This generates a shared random bit by the toss of a coin whose bias is secretly chosen, within a stipulated range, by one of the parties; the other party learns only the random bit. Thus one party can secretly influence the outcome, while both can save face by blaming any negative decisions on bad luck. We describe here some cryptographic VBCT protocols whose security is guaranteed by quantum theory and the impossibility of superluminal signaling, setting our results in the context of a general discussion of secure two-party computation. We also briefly discuss other cryptographic applications of VBCT

  14. Blood Establishment Registration Database

    Data.gov (United States)

    U.S. Department of Health & Human Services — This application provides information for active, inactive, and pre-registered firms. Query options are by FEI, Applicant Name, Establishment Name, Other Names,...

  15. Establishing software quality assurance

    International Nuclear Information System (INIS)

    Malsbury, J.

    1983-01-01

    This paper is concerned with four questions about establishing software QA: What is software QA. Why have software QA. What is the role of software QA. What is necessary to ensure the success of software QA

  16. BEHAVIORAL BIASES IN TRADING SECURITIES

    Directory of Open Access Journals (Sweden)

    Turcan Ciprian Sebastian

    2010-12-01

    Full Text Available The main thesis of this paper represents the importance and the effects that human behavior has over capital markets. It is important to see the link between the asset valuation and investor sentiment that motivate to pay for an asset a certain prices over/below the intrinsic value. The main behavioral aspects discussed are emotional factors such as: fear of regret, overconfidence, perseverance, loss aversion ,heuristic biases, misinformation and thinking errors, herding and their consequences.

  17. Establishment of floor ownership

    OpenAIRE

    Robič, Gregor

    2016-01-01

    After the socioeconomic system had been changed in 1991 the right of ownership and land registry seemed to gain a much greater importance. In that time the concept of floor ownership has also started to develop, but after 25 years a significant number of multi-unit buildings without the established floor ownership still exist in Slovenia. In this thesis both theoretical background and practical solutions for establishing a floor ownership are presented, furthermore, possible causes for an ina...

  18. Opinion dynamics with confirmation bias.

    Directory of Open Access Journals (Sweden)

    Armen E Allahverdyan

    Full Text Available Confirmation bias is the tendency to acquire or evaluate new information in a way that is consistent with one's preexisting beliefs. It is omnipresent in psychology, economics, and even scientific practices. Prior theoretical research of this phenomenon has mainly focused on its economic implications possibly missing its potential connections with broader notions of cognitive science.We formulate a (non-Bayesian model for revising subjective probabilistic opinion of a confirmationally-biased agent in the light of a persuasive opinion. The revision rule ensures that the agent does not react to persuasion that is either far from his current opinion or coincides with it. We demonstrate that the model accounts for the basic phenomenology of the social judgment theory, and allows to study various phenomena such as cognitive dissonance and boomerang effect. The model also displays the order of presentation effect-when consecutively exposed to two opinions, the preference is given to the last opinion (recency or the first opinion (primacy -and relates recency to confirmation bias. Finally, we study the model in the case of repeated persuasion and analyze its convergence properties.The standard Bayesian approach to probabilistic opinion revision is inadequate for describing the observed phenomenology of persuasion process. The simple non-Bayesian model proposed here does agree with this phenomenology and is capable of reproducing a spectrum of effects observed in psychology: primacy-recency phenomenon, boomerang effect and cognitive dissonance. We point out several limitations of the model that should motivate its future development.

  19. Opinion dynamics with confirmation bias.

    Science.gov (United States)

    Allahverdyan, Armen E; Galstyan, Aram

    2014-01-01

    Confirmation bias is the tendency to acquire or evaluate new information in a way that is consistent with one's preexisting beliefs. It is omnipresent in psychology, economics, and even scientific practices. Prior theoretical research of this phenomenon has mainly focused on its economic implications possibly missing its potential connections with broader notions of cognitive science. We formulate a (non-Bayesian) model for revising subjective probabilistic opinion of a confirmationally-biased agent in the light of a persuasive opinion. The revision rule ensures that the agent does not react to persuasion that is either far from his current opinion or coincides with it. We demonstrate that the model accounts for the basic phenomenology of the social judgment theory, and allows to study various phenomena such as cognitive dissonance and boomerang effect. The model also displays the order of presentation effect-when consecutively exposed to two opinions, the preference is given to the last opinion (recency) or the first opinion (primacy) -and relates recency to confirmation bias. Finally, we study the model in the case of repeated persuasion and analyze its convergence properties. The standard Bayesian approach to probabilistic opinion revision is inadequate for describing the observed phenomenology of persuasion process. The simple non-Bayesian model proposed here does agree with this phenomenology and is capable of reproducing a spectrum of effects observed in psychology: primacy-recency phenomenon, boomerang effect and cognitive dissonance. We point out several limitations of the model that should motivate its future development.

  20. Cognitive debiasing 1: origins of bias and theory of debiasing.

    Science.gov (United States)

    Croskerry, Pat; Singhal, Geeta; Mamede, Sílvia

    2013-10-01

    Numerous studies have shown that diagnostic failure depends upon a variety of factors. Psychological factors are fundamental in influencing the cognitive performance of the decision maker. In this first of two papers, we discuss the basics of reasoning and the Dual Process Theory (DPT) of decision making. The general properties of the DPT model, as it applies to diagnostic reasoning, are reviewed. A variety of cognitive and affective biases are known to compromise the decision-making process. They mostly appear to originate in the fast intuitive processes of Type 1 that dominate (or drive) decision making. Type 1 processes work well most of the time but they may open the door for biases. Removing or at least mitigating these biases would appear to be an important goal. We will also review the origins of biases. The consensus is that there are two major sources: innate, hard-wired biases that developed in our evolutionary past, and acquired biases established in the course of development and within our working environments. Both are associated with abbreviated decision making in the form of heuristics. Other work suggests that ambient and contextual factors may create high risk situations that dispose decision makers to particular biases. Fatigue, sleep deprivation and cognitive overload appear to be important determinants. The theoretical basis of several approaches towards debiasing is then discussed. All share a common feature that involves a deliberate decoupling from Type 1 intuitive processing and moving to Type 2 analytical processing so that eventually unexamined intuitive judgments can be submitted to verification. This decoupling step appears to be the critical feature of cognitive and affective debiasing.

  1. Developing an exchange mindset.

    Science.gov (United States)

    Thackeray, Rosemary

    2010-09-01

    Exchange is a fundamental concept that underlies all social marketing efforts. In a successful exchange, both parties receive something of value and the benefits that they desire in return for a price. The purpose of this article is to describe how practitioners can develop an "exchange mindset." A practitioner's answer to five basic questions will enable him or her to see the exchange through the eyes of the customer and increase the likelihood of creating a successful exchange that will benefit both parties involved and result in positive behavior change.

  2. Communication network exchange

    International Nuclear Information System (INIS)

    Woo, Seung Sul

    1988-05-01

    This book has two parts. The first parts is comprised of five chapters, which deals with communication network constitution with design of network and types, telephone network about outline and management of network, telephone network · data network · private network, international data telephone network about service and international data network and technical standards of quality of service, communication and data. The second parts handles exchange, which is about institution of switching, a manual exchange and step-by step exchange, a crossbar exchange, electronic exchange, international switching system, design of equipment of test and measurement.

  3. Spin quantum tunneling via entangled states in a dimer of exchange coupled single-molecule magnets

    Science.gov (United States)

    Tiron, R.; Wernsdorfer, W.; Aliaga-Alcalde, N.; Foguet-Albiol, D.; Christou, G.

    2004-03-01

    A new family of supramolecular, antiferromagnetically exchange-coupled dimers of single-molecule magnets (SMMs) has recently been reported [W. Wernsdorfer, N. Aliaga-Alcalde, D.N. Hendrickson, and G. Christou, Nature 416, 406 (2002)]. Each SMM acts as a bias on its neighbor, shifting the quantum tunneling resonances of the individual SMMs. Hysteresis loop measurements on a single crystal of SMM-dimers have now established quantum tunneling of the magnetization via entangled states of the dimer. This shows that the dimer really does behave as a quantum-mechanically coupled dimer. The transitions are well separated, suggesting long coherence times compared to the time scale of the energy splitting. This result is of great importance if such systems are to be used for quantum computing. It also allows the measurement of the longitudinal and transverse superexchange coupling constants [Phys. Rev. Lett. 91, 227203 (2003)].

  4. The Probability Distribution for a Biased Spinner

    Science.gov (United States)

    Foster, Colin

    2012-01-01

    This article advocates biased spinners as an engaging context for statistics students. Calculating the probability of a biased spinner landing on a particular side makes valuable connections between probability and other areas of mathematics. (Contains 2 figures and 1 table.)

  5. Forecasting Exchange Rate Volatility in the Presence of Jumps

    DEFF Research Database (Denmark)

    Busch, Thomas; Christensen, Bent Jesper; Nielsen, Morten Ørregaard

    We study measures of foreign exchange rate volatility based on high-frequency (5-minute) $/DM exchange rate returns using recent nonparametric statistical techniquesto compute realized return volatility and its separate continuous sample path and jumpcomponents, and measures based on prices...... of exchange rate futures options, allowingcalculation of option implied volatility. We find that implied volatility is an informationallyefficient but biased forecast of future realized exchange rate volatility. Furthermore,we show that log-normality is an even better distributional approximation...... for impliedvolatility than for realized volatility in this market. Finally, we show that the jump componentof future realized exchange rate volatility is to some extent predictable, and thatoption implied volatility is the dominant forecast of the future jump component....

  6. Expectancy bias mediates the link between social anxiety and memory bias for social evaluation.

    Science.gov (United States)

    Caouette, Justin D; Ruiz, Sarah K; Lee, Clinton C; Anbari, Zainab; Schriber, Roberta A; Guyer, Amanda E

    2015-01-01

    Social anxiety (SA) involves a multitude of cognitive symptoms related to fear of evaluation, including expectancy and memory biases. We examined whether memory biases are influenced by expectancy biases for social feedback in SA. We hypothesised that, faced with a socially evaluative event, people with higher SA would show a negative expectancy bias for future feedback. Furthermore, we predicted that memory bias for feedback in SA would be mediated by expectancy bias. Ninety-four undergraduate students (55 women, mean age = 19.76 years) underwent a two-visit task that measured expectations about (Visit 1) and memory of (Visit 2) feedback from unknown peers. Results showed that higher levels of SA were associated with negative expectancy bias. An indirect relationship was found between SA and memory bias that was mediated by expectancy bias. The results suggest that expectancy biases are in the causal path from SA to negative memory biases for social evaluation.

  7. Culturally Biased Assumptions in Counseling Psychology

    Science.gov (United States)

    Pedersen, Paul B.

    2003-01-01

    Eight clusters of culturally biased assumptions are identified for further discussion from Leong and Ponterotto's (2003) article. The presence of cultural bias demonstrates that cultural bias is so robust and pervasive that is permeates the profession of counseling psychology, even including those articles that effectively attack cultural bias…

  8. Using Newspapers to Study Media Bias.

    Science.gov (United States)

    Kirman, Joseph M.

    1992-01-01

    Suggests that students can learn to recognize media bias by studying media reports of current events or historical topics. Describes a study unit using media coverage of the second anniversary of the Palestinian uprising against Israel. Discusses lesson objectives, planning, defining bias teaching procedures, and criteria for determining bias. (DK)

  9. Attentional bias predicts heroin relapse following treatment

    NARCIS (Netherlands)

    Marissen, Marlies A. E.; Franken, Ingmar H. A.; Waters, Andrew J.; Blanken, Peter; van den Brink, Wim; Hendriks, Vincent M.

    2006-01-01

    AIMS: Previous studies have shown that abstinent heroin addicts exhibit an attentional bias to heroin-related stimuli. It has been suggested that attentional bias may represent a vulnerability to relapse into drug use. In the present study, the predictive value of pre-treatment attentional bias on

  10. Automated exchange transfusion and exchange rate.

    Science.gov (United States)

    Funato, M; Shimada, S; Tamai, H; Taki, H; Yoshioka, Y

    1989-10-01

    An automated blood exchange transfusion (BET) with a two-site technique has been devised by Goldmann et al and by us, using an infusion pump. With this method, we successfully performed exchange transfusions 189 times in the past four years on 110 infants with birth weights ranging from 530 g to 4,000 g. The exchange rate by the automated method was compared with the rate by Diamond's method. Serum bilirubin (SB) levels before and after BET and the maximal SB rebound within 24 hours after BET were: 21.6 +/- 2.4, 11.5 +/- 2.2, and 15.0 +/- 1.5 mg/dl in the automated method, and 22.0 +/- 2.9, 11.2 +/- 2.5, and 17.7 +/- 3.2 mg/dl in Diamond's method, respectively. The result showed that the maximal rebound of the SB level within 24 hours after BET was significantly lower in the automated method than in Diamond's method (p less than 0.01), though SB levels before and after BET were not significantly different between the two methods. The exchange rate was also measured by means of staining the fetal red cells (F cells) both in the automated method and in Diamond's method, and comparing them. The exchange rate of F cells in Diamond's method went down along the theoretical exchange curve proposed by Diamond, while the rate in the automated method was significantly better than in Diamond's, especially in the early stage of BET (p less than 0.01). We believe that the use of this automated method may give better results than Diamond's method in the rate of exchange, because this method is performed with a two-site technique using a peripheral artery and vein.

  11. Opinion Dynamics with Confirmation Bias

    Science.gov (United States)

    Allahverdyan, Armen E.; Galstyan, Aram

    2014-01-01

    Background Confirmation bias is the tendency to acquire or evaluate new information in a way that is consistent with one's preexisting beliefs. It is omnipresent in psychology, economics, and even scientific practices. Prior theoretical research of this phenomenon has mainly focused on its economic implications possibly missing its potential connections with broader notions of cognitive science. Methodology/Principal Findings We formulate a (non-Bayesian) model for revising subjective probabilistic opinion of a confirmationally-biased agent in the light of a persuasive opinion. The revision rule ensures that the agent does not react to persuasion that is either far from his current opinion or coincides with it. We demonstrate that the model accounts for the basic phenomenology of the social judgment theory, and allows to study various phenomena such as cognitive dissonance and boomerang effect. The model also displays the order of presentation effect–when consecutively exposed to two opinions, the preference is given to the last opinion (recency) or the first opinion (primacy) –and relates recency to confirmation bias. Finally, we study the model in the case of repeated persuasion and analyze its convergence properties. Conclusions The standard Bayesian approach to probabilistic opinion revision is inadequate for describing the observed phenomenology of persuasion process. The simple non-Bayesian model proposed here does agree with this phenomenology and is capable of reproducing a spectrum of effects observed in psychology: primacy-recency phenomenon, boomerang effect and cognitive dissonance. We point out several limitations of the model that should motivate its future development. PMID:25007078

  12. Examining Event-Related Potential (ERP correlates of decision bias in recognition memory judgments.

    Directory of Open Access Journals (Sweden)

    Holger Hill

    Full Text Available Memory judgments can be based on accurate memory information or on decision bias (the tendency to report that an event is part of episodic memory when one is in fact unsure. Event related potentials (ERP correlates are important research tools for elucidating the dynamics underlying memory judgments but so far have been established only for investigations of accurate old/new discrimination. To identify the ERP correlates of bias, and observe how these interact with ERP correlates of memory, we conducted three experiments that manipulated decision bias within participants via instructions during recognition memory tests while their ERPs were recorded. In Experiment 1, the bias manipulation was performed between blocks of trials (automatized bias and compared to trial-by-trial shifts of bias in accord with an external cue (flexibly controlled bias. In Experiment 2, the bias manipulation was performed at two different levels of accurate old/new discrimination as the memory strength of old (studied items was varied. In Experiment 3, the bias manipulation was added to another, bottom-up driven manipulation of bias induced via familiarity. In the first two Experiments, and in the low familiarity condition of Experiment 3, we found evidence of an early frontocentral ERP component at 320 ms poststimulus (the FN320 that was sensitive to the manipulation of bias via instruction, with more negative amplitudes indexing more liberal bias. By contrast, later during the trial (500-700 ms poststimulus, bias effects interacted with old/new effects across all three experiments. Results suggest that the decision criterion is typically activated early during recognition memory trials, and is integrated with retrieved memory signals and task-specific processing demands later during the trial. More generally, the findings demonstrate how ERPs can help to specify the dynamics of recognition memory processes under top-down and bottom-up controlled retrieval conditions.

  13. Examining Event-Related Potential (ERP) Correlates of Decision Bias in Recognition Memory Judgments

    Science.gov (United States)

    Hill, Holger; Windmann, Sabine

    2014-01-01

    Memory judgments can be based on accurate memory information or on decision bias (the tendency to report that an event is part of episodic memory when one is in fact unsure). Event related potentials (ERP) correlates are important research tools for elucidating the dynamics underlying memory judgments but so far have been established only for investigations of accurate old/new discrimination. To identify the ERP correlates of bias, and observe how these interact with ERP correlates of memory, we conducted three experiments that manipulated decision bias within participants via instructions during recognition memory tests while their ERPs were recorded. In Experiment 1, the bias manipulation was performed between blocks of trials (automatized bias) and compared to trial-by-trial shifts of bias in accord with an external cue (flexibly controlled bias). In Experiment 2, the bias manipulation was performed at two different levels of accurate old/new discrimination as the memory strength of old (studied) items was varied. In Experiment 3, the bias manipulation was added to another, bottom-up driven manipulation of bias induced via familiarity. In the first two Experiments, and in the low familiarity condition of Experiment 3, we found evidence of an early frontocentral ERP component at 320 ms poststimulus (the FN320) that was sensitive to the manipulation of bias via instruction, with more negative amplitudes indexing more liberal bias. By contrast, later during the trial (500–700 ms poststimulus), bias effects interacted with old/new effects across all three experiments. Results suggest that the decision criterion is typically activated early during recognition memory trials, and is integrated with retrieved memory signals and task-specific processing demands later during the trial. More generally, the findings demonstrate how ERPs can help to specify the dynamics of recognition memory processes under top-down and bottom-up controlled retrieval conditions. PMID

  14. Examining Event-Related Potential (ERP) correlates of decision bias in recognition memory judgments.

    Science.gov (United States)

    Hill, Holger; Windmann, Sabine

    2014-01-01

    Memory judgments can be based on accurate memory information or on decision bias (the tendency to report that an event is part of episodic memory when one is in fact unsure). Event related potentials (ERP) correlates are important research tools for elucidating the dynamics underlying memory judgments but so far have been established only for investigations of accurate old/new discrimination. To identify the ERP correlates of bias, and observe how these interact with ERP correlates of memory, we conducted three experiments that manipulated decision bias within participants via instructions during recognition memory tests while their ERPs were recorded. In Experiment 1, the bias manipulation was performed between blocks of trials (automatized bias) and compared to trial-by-trial shifts of bias in accord with an external cue (flexibly controlled bias). In Experiment 2, the bias manipulation was performed at two different levels of accurate old/new discrimination as the memory strength of old (studied) items was varied. In Experiment 3, the bias manipulation was added to another, bottom-up driven manipulation of bias induced via familiarity. In the first two Experiments, and in the low familiarity condition of Experiment 3, we found evidence of an early frontocentral ERP component at 320 ms poststimulus (the FN320) that was sensitive to the manipulation of bias via instruction, with more negative amplitudes indexing more liberal bias. By contrast, later during the trial (500-700 ms poststimulus), bias effects interacted with old/new effects across all three experiments. Results suggest that the decision criterion is typically activated early during recognition memory trials, and is integrated with retrieved memory signals and task-specific processing demands later during the trial. More generally, the findings demonstrate how ERPs can help to specify the dynamics of recognition memory processes under top-down and bottom-up controlled retrieval conditions.

  15. On Size Biased Kumaraswamy Distribution

    Directory of Open Access Journals (Sweden)

    Dreamlee Sharma

    2016-08-01

    Full Text Available In this paper, we introduce and study the size-biased form of Kumaraswamy distribution. The Kumaraswamy distribution which has drawn considerable attention in hydrology and related areas was proposed by Kumarswamy. The new distribution is derived under sizebiased probability of sampling taking the weights as the variate values. Various distributional and characterizing properties of the model are studied. The methods of maximum likelihood and matching quantiles estimation are employed to estimate the parameters of the proposed model. Finally, we apply the proposed model to simulated and real data sets.

  16. Establishing a University Foundation.

    Science.gov (United States)

    Lemish, Donald L.

    A handbook on how to establish a university foundation is presented. It presupposes that a foundation will be used as the umbrella organization for receiving all private gifts, restricted and unrestricted, for the benefit of a public college or university; and hence it chiefly addresses readers from public colleges and universities. Information is…

  17. Secular Religious Establishment

    DEFF Research Database (Denmark)

    Lægaard, Sune

    2013-01-01

    Secularism as a political doctrine claims that religion and politics should be separated. The compatibility question is whether secularism can accept some forms of religious establishment in the form of institutional linkages between state and organised religion. I argue that the answer to the co...

  18. Antiphase boundaries induced exchange coupling in epitaxial Fe3O4 thin films

    International Nuclear Information System (INIS)

    Arora, S.K.; Sofin, R.G.S.; Nolan, A.; Shvets, I.V.

    2005-01-01

    We have observed an exchange bias effect on field cooling of epitaxial magnetite, Fe 3 O 4 , films on MgO (1 0 0) substrates. We attribute this effect to the presence of antiphase boundaries (APBs). Magnitude of the exchange bias field (H e ) strongly depends on the thermo-magnetic history of the sample. The strength of the H e was found to increase with an increase in film thickness and is attributed to the strain driven redistribution of atoms in the vicinity of APBs leading to enhanced antiferromagnetic exchange interactions

  19. Personality Traits and Susceptibility to Behavioral Biases among a Sample of Polish Stock Market Investors

    Directory of Open Access Journals (Sweden)

    Rzeszutek Marcin

    2015-09-01

    Full Text Available The aim of this paper is to investigate whether susceptibility to selected behavioral biases (overconfidence, mental accounting and sunk-cost fallacy is correlated with the Eysenck’s [1978] personality traits (impulsivity, venturesomeness, and empathy. This study was conducted on a sample of 90 retail investors frequently investing on the Warsaw Stock Exchange. Participants filled out a survey made up of two parts: 1 three situational exercises, which assessed susceptibility to behavioral biases and 2 an Impulsiveness Questionnaire, which measures impulsivity, venturesomeness, and empathy. The results demonstrated the relationship between venturesomeness and susceptibility to all behavioral biases explored in this study. We find that higher level of venturesomeness was linked with a lower probability of all behavioral biases included in this study.

  20. 17 CFR 10.114 - Acceleration of establishment of restitution procedure.

    Science.gov (United States)

    2010-04-01

    ... 17 Commodity and Securities Exchanges 1 2010-04-01 2010-04-01 false Acceleration of establishment of restitution procedure. 10.114 Section 10.114 Commodity and Securities Exchanges COMMODITY FUTURES TRADING COMMISSION RULES OF PRACTICE Restitution Orders § 10.114 Acceleration of establishment of...

  1. Effects of imaging gradients in sequences with varying longitudinal storage time-Case of diffusion exchange imaging

    DEFF Research Database (Denmark)

    Lasic, Samo; Lundell, Henrik; Topgaard, Daniel

    2017-01-01

    low-pass diffusion filtering during the LS interval, which is more pronounced at lower exchange rates. For a total exchange rate constant larger than 1 s-1, the AXR bias is expected to be negligible when slices thicker than 2.5mm are used. Conclusion: In correlation experiments like FEXI, relying......Purpose: To illustrate the potential bias caused by imaging gradients in correlation MRI sequences using longitudinal magnetization storage (LS) and examine the case of filter exchange imaging (FEXI) yielding maps of the apparent exchange rate (AXR). Methods: The effects of imaging gradients...

  2. Laser Processed Heat Exchangers

    Science.gov (United States)

    Hansen, Scott

    2017-01-01

    The Laser Processed Heat Exchanger project will investigate the use of laser processed surfaces to reduce mass and volume in liquid/liquid heat exchangers as well as the replacement of the harmful and problematic coatings of the Condensing Heat Exchangers (CHX). For this project, two scale unit test articles will be designed, manufactured, and tested. These two units are a high efficiency liquid/liquid HX and a high reliability CHX.

  3. Microsoft Exchange 2013 cookbook

    CERN Document Server

    Van Horenbeeck, Michael

    2013-01-01

    This book is a practical, hands-on guide that provides the reader with a number of clear, step-by-step exercises.""Microsoft Exchange 2013 Cookbook"" is targeted at network administrators who deal with the Exchange server in their day-to-day jobs. It assumes you have some practical experience with previous versions of Exchange (although this is not a requirement), without being a subject matter expert.

  4. Motion signals bias localization judgments

    Science.gov (United States)

    Eagleman, David M.; Sejnowski, Terrence J.

    2008-01-01

    In the flash-lag illusion, a moving object aligned with a flash is perceived to be offset in the direction of motion following the flash. In the “flash-drag” illusion, a flash is mislocalized in the direction of nearby motion. In the “flash-jump” illusion, a transient change in the appearance of a moving object (e.g., color) is mislocalized in the direction of subsequent motion. Finally, in the Frohlich illusion, the starting position of a suddenly appearing moving object is mislocalized in the direction of the subsequent motion. We demonstrate, in a series of experiments, a unified explanation for all these illusions: Perceptual localization is influenced by motion signals collected over ∼80 ms after a query is triggered. These demonstrations rule out “latency difference” and asynchronous feature binding models, in which objects appear in their real positions but misaligned in time. Instead, the illusions explored here are best understood as biases in localization caused by motion signals. We suggest that motion biasing exists because it allows the visual system to account for neural processing delays by retrospectively “pushing” an object closer to its true physical location, and we propose directions for exploring the neural mechanisms underlying the dynamic updating of location by the activity of motion-sensitive neurons. PMID:17461687

  5. Workplace ageism: discovering hidden bias.

    Science.gov (United States)

    Malinen, Sanna; Johnston, Lucy

    2013-01-01

    BACKGROUND/STUDY CONTEXT: Research largely shows no performance differences between older and younger employees, or that older workers even outperform younger employees, yet negative attitudes towards older workers can underpin discrimination. Unfortunately, traditional "explicit" techniques for assessing attitudes (i.e., self-report measures) have serious drawbacks. Therefore, using an approach that is novel to organizational contexts, the authors supplemented explicit with implicit (indirect) measures of attitudes towards older workers, and examined the malleability of both. This research consists of two studies. The authors measured self-report (explicit) attitudes towards older and younger workers with a survey, and implicit attitudes with a reaction-time-based measure of implicit associations. In addition, to test whether attitudes were malleable, the authors measured attitudes before and after a mental imagery intervention, where the authors asked participants in the experimental group to imagine respected and valued older workers from their surroundings. Negative, stable implicit attitudes towards older workers emerged in two studies. Conversely, explicit attitudes showed no age bias and were more susceptible to change intervention, such that attitudes became more positive towards older workers following the experimental manipulation. This research demonstrates the unconscious nature of bias against older workers, and highlights the utility of implicit attitude measures in the context of the workplace. In the current era of aging workforce and skill shortages, implicit measures may be necessary to illuminate hidden workplace ageism.

  6. Gender Bias Affects Forests Worldwide

    Directory of Open Access Journals (Sweden)

    Marlène Elias

    2017-04-01

    Full Text Available Gender biases persist in forestry research and practice. These biases result in reduced scientific rigor and inequitable, ineffective, and less efficient policies, programs, and interventions. Drawing from a two-volume collection of current and classic analyses on gender in forests, we outline five persistent and inter-related themes: gendered governance, tree tenure, forest spaces, division of labor, and ecological knowledge. Each emerges across geographic regions in the northern and southern hemisphere and reflects inequities in women’s and men’s ability to make decisions about and benefit from trees, forests, and their products. Women’s ability to participate in community-based forest governance is typically less than men’s, causing concern for social equity and forest stewardship. Women’s access to trees and their products is commonly more limited than men’s, and mediated by their relationship with their male counterparts. Spatial patterns of forest use reflect gender norms and taboos, and men’s greater access to transportation. The division of labor results in gender specialization in the collection of forest products, with variations in gender roles across regions. All these gender differences result in ecological knowledge that is distinct but also complementary and shifting across the genders. The ways gender plays out in relation to each theme may vary across cultures and contexts, but the influence of gender, which intersects with other factors of social differentiation in shaping forest landscapes, is global.

  7. Volunteer bias, sexuality, and personality.

    Science.gov (United States)

    Trivedi, N; Sabini, J

    1998-04-01

    Participants were recruited either for a study of sexual attitudes and behavior or for a study of attitudes and behavior without mention of sexuality. Both groups answered questions about their sexual behavior and completed the Self-Monitoring Scale, the Balanced F Scale, and the Social Responsibility Scale. No differences were found as a function of recruitment technique in the mean reports of subjects' sexual behavior, but substantial differences were found in some of the relationships between these personality variables and sexual behavior reports as a function of recruitment technique; the correlation between the balanced F Scale score and masturbation frequency for females was +0.61 for those recruited for a study of sexual behavior and -0.61 for those recruited for a study of general attitudes and behavior. In both groups, larger correlations were found between female sexual behavior and personality than between male sexual behavior and personality. In all groups, the Self-Monitoring Scale was significantly correlated with masturbation frequency. The results are discussed in terms of self-selection bias and self-presentation bias, both of which may affect research on sexuality.

  8. Ion exchange fiber by radiation grafting, 1

    International Nuclear Information System (INIS)

    Fujiwara, Kunio

    1990-01-01

    Radiation grafting is gaining attention as a method for producing high performance materials. This method can be applied to add functions to existing polymer plastics. The author participated in the research program on the production of ion exchange fiber by radiation grafting and its applicability at the Japan Atomic Energy Research Institute, Takasaki Radiation Chemistry Research Establishment. Consequently, it was clarified that it was possible to introduce the cation exchange group, represented by sulfonic and carboxyl groups, and the anion exchange group, represented by the quarternary ammonium group, to polypropylene fiber available on the market. The ion exchange capacity was able to be controlled by the degree of grafting, i.e. approximately up to 3 meq/g in both strong acid and strong base and approximately up to 5 meq/g in weak acid were obtained. The adsorption performance of ammonia, a representative malodorous substance, was also studied using test cation exchange fiber. The adsorption rate of H type strong acid cation exchange fiber was great, due to the H type having neutral reaction, and the adsorption capacity matched the ion exchange capacity. Although the Cu and Ni types features coordinated adsorption and their adsorption rates were from 1/2 to 1/3 of that of the H type, their adsorption capacities showed increase along with the metal adsorbed. (author)

  9. 12 CFR 614.4900 - Foreign exchange.

    Science.gov (United States)

    2010-01-01

    ... Banks and Banking FARM CREDIT ADMINISTRATION FARM CREDIT SYSTEM LOAN POLICIES AND OPERATIONS Banks for Cooperatives and Agricultural Credit Banks Financing International Trade § 614.4900 Foreign exchange. (a... international financial activities. The bank's policies should include established guidelines for: (1) Net...

  10. Alcohol breath test: gas exchange issues.

    Science.gov (United States)

    Hlastala, Michael P; Anderson, Joseph C

    2016-08-01

    The alcohol breath test is reviewed with a focus on gas exchange factors affecting its accuracy. The basis of the alcohol breath test is the assumption that alveolar air reaches the mouth during exhalation with no change in alcohol concentration. Recent investigations have shown that alcohol concentration is altered during its transit to the mouth. The exhaled alcohol concentration is modified by interaction with the mucosa of the pulmonary airways. Exhaled alcohol concentration is not an accurate indicator of alveolar alcohol concentration. Measuring alcohol concentration in the breath is very different process than measuring a blood level from air equilibrated with a blood sample. Airway exchange of alcohol leads to a bias against certain individuals depending on the anatomic and physiologic characteristics. Methodological modifications are proposed to improve the accuracy of the alcohol breath test to become fair to all. Copyright © 2016 the American Physiological Society.

  11. Model bias for South Atlantic Antarctic intermediate water in CMIP5

    Science.gov (United States)

    Zhu, Chenyu; Liu, Zhengyu; Gu, Sifan

    2017-07-01

    Characterized by a salinity minimum in the mid-depth, the Antarctic Intermediate Water (AAIW) is an important component of global ocean water mass. The simulation of the AAIW in current climate models, however, has remained deficient, especially in the Atlantic sector. Here, we evaluate the simulation of the South Atlantic AAIW in eleven state-of-the-art coupled climate models. It is found that all the models show a common AAIW bias relative to the observation, with a saltier, warmer and lighter core located at a shallower depth. This AAIW bias seems to contribute to a deficient freshwater export by the Atlantic Meridional Overturning Circulation (AMOC), potentially overstabilizing the AMOC. The causes of the bias are investigated in sensitivity experiments using an ocean alone model. It is found that the AAIW bias is caused neither by the surface climate bias nor the North Atlantic bias, although is weakly affected by the inter-basin exchange. This left the conclusion that the AAIW bias is caused predominantly by the deficient model representation of ocean dynamics and mixing processes in the AAIW region.

  12. Social Representation of Intercultural Exchange in an International University

    Science.gov (United States)

    Kudo, Kazuhiro

    2016-01-01

    This paper provides an interpretive investigation into the social representation of intercultural exchange at one of the newly established international universities in Japan. The author conducted quasi-structured interviews with 5 staff members and 22 students to gain insight into their perceptions of intercultural exchange and interactions. The…

  13. Intergroup biases and eyewitness testimony.

    Science.gov (United States)

    Lindholm, T; Christianson, S A

    1998-12-01

    The study examined how the in-group/out-group status of a perpetrator of a distinctly violent crime might influence an eyewitness's evaluation of his behavior and a witness's performance in an identification task. Immigrant and Swedish students saw a film showing a simulated robbery, with an immigrant or a Swede as the perpetrator. Results showed that both groups evaluated an ethnically dissimilar perpetrator as more culpable than an ethnically similar perpetrator. In a line-up task, both immigrant and Swedish participants mistakenly identified an innocent immigrant more often than an innocent Swede. Participants' biased evaluations of the perpetrator are discussed in terms of cognitive and motivational mechanisms. Expectations regarding the typical ethnicity of a perpetrator of this type of crime are suggested to account for the findings of the line-up task.

  14. Optimization of Heat Exchangers

    International Nuclear Information System (INIS)

    Catton, Ivan

    2010-01-01

    The objective of this research is to develop tools to design and optimize heat exchangers (HE) and compact heat exchangers (CHE) for intermediate loop heat transport systems found in the very high temperature reator (VHTR) and other Generation IV designs by addressing heat transfer surface augmentation and conjugate modeling. To optimize heat exchanger, a fast running model must be created that will allow for multiple designs to be compared quickly. To model a heat exchanger, volume averaging theory, VAT, is used. VAT allows for the conservation of mass, momentum and energy to be solved for point by point in a 3 dimensional computer model of a heat exchanger. The end product of this project is a computer code that can predict an optimal configuration for a heat exchanger given only a few constraints (input fluids, size, cost, etc.). As VAT computer code can be used to model characteristics (pumping power, temperatures, and cost) of heat exchangers more quickly than traditional CFD or experiment, optimization of every geometric parameter simultaneously can be made. Using design of experiment, DOE and genetric algorithms, GE, to optimize the results of the computer code will improve heat exchanger design.

  15. Higher Education Exchange, 2010

    Science.gov (United States)

    Brown, David W., Ed.; Witte, Deborah, Ed.

    2010-01-01

    "Higher Education Exchange" publishes case studies, analyses, news, and ideas about efforts within higher education to develop more democratic societies. Contributors to this issue of the "Higher Education Exchange" examine whether institutions of higher learning are doing anything to increase the capacity of citizens to shape their future.…

  16. Higher Education Exchange, 2012

    Science.gov (United States)

    Brown, David W., Ed.; Witte, Deborah, Ed.

    2012-01-01

    "Higher Education Exchange" publishes case studies, analyses, news, and ideas about efforts within higher education to develop more democratic societies. Contributors to this issue of the "Higher Education Exchange" examine whether institutions of higher learning are doing anything to increase the capacity of citizens to shape…

  17. Higher Education Exchange, 2011

    Science.gov (United States)

    Brown, David W., Ed.; Witte, Deborah, Ed.

    2011-01-01

    "Higher Education Exchange" publishes case studies, analyses, news, and ideas about efforts within higher education to develop more democratic societies. Contributors to this issue of the "Higher Education Exchange" examine whether institutions of higher learning are doing anything to increase the capacity of citizens to shape…

  18. French chemical exchange process

    International Nuclear Information System (INIS)

    Frejacques, C.; Lerat, J.-M.; Plurien, P.

    1979-01-01

    A new chemical exchange reaction between two forms of uranium compounds with a high elementary separation coefficient and good kinetics has been discovered at the French Energy Commission ten years ago and developed to the industrial stage. We give here some general characteristics of the process and discuss some parameters of the kinetics exchange

  19. Direct fired heat exchanger

    Science.gov (United States)

    Reimann, Robert C.; Root, Richard A.

    1986-01-01

    A gas-to-liquid heat exchanger system which transfers heat from a gas, generally the combustion gas of a direct-fired generator of an absorption machine, to a liquid, generally an absorbent solution. The heat exchanger system is in a counterflow fluid arrangement which creates a more efficient heat transfer.

  20. Optimization of Heat Exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Ivan Catton

    2010-10-01

    The objective of this research is to develop tools to design and optimize heat exchangers (HE) and compact heat exchangers (CHE) for intermediate loop heat transport systems found in the very high temperature reator (VHTR) and other Generation IV designs by addressing heat transfer surface augmentation and conjugate modeling. To optimize heat exchanger, a fast running model must be created that will allow for multiple designs to be compared quickly. To model a heat exchanger, volume averaging theory, VAT, is used. VAT allows for the conservation of mass, momentum and energy to be solved for point by point in a 3 dimensional computer model of a heat exchanger. The end product of this project is a computer code that can predict an optimal configuration for a heat exchanger given only a few constraints (input fluids, size, cost, etc.). As VAT computer code can be used to model characteristics )pumping power, temperatures, and cost) of heat exchangers more quickly than traditional CFD or experiment, optimization of every geometric parameter simultaneously can be made. Using design of experiment, DOE and genetric algorithms, GE, to optimize the results of the computer code will improve heat exchanger disign.

  1. Motivation for International Exchange.

    Science.gov (United States)

    Brewer, Elizabeth

    An objective analysis of students' initial motivation for studying overseas was attempted by surveying students before they embarked on their exchange programs. Eighty-eight students who were planning to study in France, Great Britain, Germany, and the People's Republic of China were surveyed. The exchange program was sponsored by the University…

  2. Re-establishing dignity

    DEFF Research Database (Denmark)

    Høy, Bente; Hall, E.O.C

    2012-01-01

    study with 29 nurses and nurse assistants was performed following Van Manen’s hermeneutic phenomenology. Findings show that caring mainly concerns ‘re-establishing dignity’ especially through ‘seeing the patient as a unique person’, ‘assisting in getting rid of the bed’ and ‘supporting patient...... appearance’. The study documents that caring for older people is about creating small everyday circumstances in which patient dignity can flourish. Shortcomings of a secondary analysis are discussed and suggestions for future research, such as how older hospital patients experience caring and dignity...

  3. Revival of test bias research in preemployment testing.

    Science.gov (United States)

    Aguinis, Herman; Culpepper, Steven A; Pierce, Charles A

    2010-07-01

    We developed a new analytic proof and conducted Monte Carlo simulations to assess the effects of methodological and statistical artifacts on the relative accuracy of intercept- and slope-based test bias assessment. The main simulation design included 3,185,000 unique combinations of a wide range of values for true intercept- and slope-based test bias, total sample size, proportion of minority group sample size to total sample size, predictor (i.e., preemployment test scores) and criterion (i.e., job performance) reliability, predictor range restriction, correlation between predictor scores and the dummy-coded grouping variable (e.g., ethnicity), and mean difference between predictor scores across groups. Results based on 15 billion 925 million individual samples of scores and more than 8 trillion 662 million individual scores raise questions about the established conclusion that test bias in preemployment testing is nonexistent and, if it exists, it only occurs regarding intercept-based differences that favor minority group members. Because of the prominence of test fairness in the popular media, legislation, and litigation, our results point to the need to revive test bias research in preemployment testing.

  4. Standardizing exchange formats

    International Nuclear Information System (INIS)

    Lemmel, H.D.; Schmidt, J.J.

    1992-01-01

    An international network of co-operating data centres is described who maintain identical data bases which are simultaneously updated by an agreed data exchange procedure. The agreement covers ''data exchange formats'' which are compatible to the centres' internal data storage and retrieval systems which remain different, optimized at each centre to the available computer facilities and to the needs of the data users. Essential condition for the data exchange is an agreement on common procedures for the data exchange is an agreement on common procedures for the data compilation, including critical data analysis and validation. The systems described (''EXFOR'', ''ENDF'', ''CINDA'') are used for ''nuclear reaction data'', but the principles used for data compilation and exchange should be valid also for other data types. (author). 24 refs, 4 figs

  5. When Novel Rituals Lead to Intergroup Bias: Evidence From Economic Games and Neurophysiology.

    Science.gov (United States)

    Hobson, Nicholas M; Gino, Francesca; Norton, Michael I; Inzlicht, Michael

    2017-06-01

    Long-established rituals in preexisting cultural groups have been linked to the cultural evolution of group cooperation. We tested the prediction that novel rituals-arbitrary hand and body gestures enacted in a stereotypical and repeated fashion-can inculcate intergroup bias in newly formed groups. In four experiments, participants practiced novel rituals at home for 1 week (Experiments 1, 2, and 4) or once in the lab (Experiment 3) and were divided into minimal in-groups and out-groups. Our results offer mixed support for the hypothesis that novel rituals promote intergroup bias. Specifically, we found a modest effect for daily repeated rituals but a null effect for rituals enacted only once. These results suggest that novel rituals can inculcate bias, but only when certain features are present: Rituals must be sufficiently elaborate and repeated to lead to bias. Taken together, our results offer modest support that novel rituals can promote intergroup bias.

  6. A Short note on Accent–bias, Social Identity and Ethnocentrism

    Directory of Open Access Journals (Sweden)

    Rahul Chakraborty

    2017-08-01

    Full Text Available This paper discusses the interrelations among accent-based biases, social identity and ethnocentrism. Construction of social identity creates a set of ethnocentric values within a person, which indirectly or directly plays a pivotal role in generating accent related biases. Starting with Tajfel’s (1959 social identity theory and then the discussion of ethnocentrism, accent related biases have a long documented origin, development and consequences. People construct their social identity based on numerous variables and then their in-group and out-group memberships are established. Ethnocentrism, as a variable, influences listeners’ accent perception and subsequent judgment regarding their perceived accent. The degree of ethnocentrism is related to speakers’ potential accent biases. As legal safeguard against accent related biases is absent, active resistance and awareness-initiation are expected from speech language pathologists and the concerned community in general. Role of training institutions is discussed.

  7. Professional Culture and Climate: Addressing Unconscious Bias

    Science.gov (United States)

    Knezek, Patricia

    2016-10-01

    Unconscious bias reflects expectations or stereotypes that influence our judgments of others (regardless of our own group). Everyone has unconscious biases. The end result of unconscious bias can be an accumulation of advantage or disadvantage that impacts the long term career success of individuals, depending on which biases they are subject to. In order to foster a professional culture and climate, being aware of these unconscious biases and mitigating against them is a first step. This is particularly important when judgements are needed, such as in cases for recruitment, choice of speakers for conferences, and even reviewing papers submitted for publication. This presentation will cover how unconscious bias manifests itself, what evidence exists to demonstrate it exists, and ways it can be addressed.

  8. Symmetry as Bias: Rediscovering Special Relativity

    Science.gov (United States)

    Lowry, Michael R.

    1992-01-01

    This paper describes a rational reconstruction of Einstein's discovery of special relativity, validated through an implementation: the Erlanger program. Einstein's discovery of special relativity revolutionized both the content of physics and the research strategy used by theoretical physicists. This research strategy entails a mutual bootstrapping process between a hypothesis space for biases, defined through different postulated symmetries of the universe, and a hypothesis space for physical theories. The invariance principle mutually constrains these two spaces. The invariance principle enables detecting when an evolving physical theory becomes inconsistent with its bias, and also when the biases for theories describing different phenomena are inconsistent. Structural properties of the invariance principle facilitate generating a new bias when an inconsistency is detected. After a new bias is generated. this principle facilitates reformulating the old, inconsistent theory by treating the latter as a limiting approximation. The structural properties of the invariance principle can be suitably generalized to other types of biases to enable primal-dual learning.

  9. Attentional bias in obsessional compulsive disorder.

    Science.gov (United States)

    Tata, P R; Leibowitz, J A; Prunty, M J; Cameron, M; Pickering, A D

    1996-01-01

    To date, studies of information processing in anxiety disorders have suggested that the latter are characterised by vigilance for threatening stimuli, possibly specific to personally relevant threat content. The present study represents an attempt to establish whether patients suffering from Obsessional Compulsive Disorder (OCD), generally classified as an anxiety disorder, show a similar cognitive bias. Thus, a replication of MacLeod, Mathews and Tata's (1986) study [Journal of Abnormal Psychology, 95, 15-20] is reported, employing modified materials of direct concern to the OCD subjects i.e. Contamination-related words. The results did indeed reveal content specific vigilance, whereby the OCD group were more vigilant for contamination content than mood-matched High Trait Anxious (HTA) controls, but the reverse was true for Social Anxiety words. Additionally, while a general threat interference effect was identified for both OCD and HTA subjects this was not content specific. A second experiment employing Low Trait Anxious subjects revealed no vigilance for threat nor any threat interference in this sample. The clinical implications and possible mechanism underlying these results are discussed.

  10. Avoiding self-repulsion in density functional description of biased molecular junctions

    International Nuclear Information System (INIS)

    Baer, Roi; Livshits, Ester; Neuhauser, Daniel

    2006-01-01

    We examine the effects of self-repulsion on the predictions of charge distribution in biased molecular junctions by the local density functional theory methods. This is done using a functional with explicit long-range exchange term effects [R. Baer, D. Neuhauser, Phys. Rev. Lett. 94 (2005) 043002]. We discuss in detail the new density functional, pointing out some of the remaining difficulties in the theory. We find that in weakly coupled junctions (the typical molecular electronics case) local-density functionals fail to describe correctly the charge distribution in the intermediate bias regime

  11. Influence of the impurity-scattering on zero-bias conductance peak in ferromagnet/insulator/d-wave superconductor junctions

    CERN Document Server

    Yoshida, N; Itoh, H; Tanaka, Y; Inoue, J I; Kashiwaya, S

    2003-01-01

    Effects of impurity-scattering on a zero-bias conductance peak in ferromagnet/insulator/d-wave superconductor junctions are theoretically studied. The impurities are introduced through the random potential in ferromagnets near the junction interface. As in the case of normal-metal/insulator/d-wave superconductor junctions, the magnitude of zero-bias conductance peak decreases with increasing the degree of disorder. However, when the magnitude of the exchange potential in ferromagnet is sufficiently large, the random potential can enhance the zero-bias conductance peak in ferromagnetic junctions. (author)

  12. Biased but in doubt: conflict and decision confidence.

    Directory of Open Access Journals (Sweden)

    Wim De Neys

    Full Text Available Human reasoning is often biased by intuitive heuristics. A central question is whether the bias results from a failure to detect that the intuitions conflict with traditional normative considerations or from a failure to discard the tempting intuitions. The present study addressed this unresolved debate by using people's decision confidence as a nonverbal index of conflict detection. Participants were asked to indicate how confident they were after solving classic base-rate (Experiment 1 and conjunction fallacy (Experiment 2 problems in which a cued intuitive response could be inconsistent or consistent with the traditional correct response. Results indicated that reasoners showed a clear confidence decrease when they gave an intuitive response that conflicted with the normative response. Contrary to popular belief, this establishes that people seem to acknowledge that their intuitive answers are not fully warranted. Experiment 3 established that younger reasoners did not yet show the confidence decrease, which points to the role of improved bias awareness in our reasoning development. Implications for the long standing debate on human rationality are discussed.

  13. International exchange of safety and licensing information

    International Nuclear Information System (INIS)

    Lafleur, J.D. Jr.; Hauber, R.D.; Chenier, D.M.

    1977-01-01

    A network of formal and informal bilateral arrangements for the exchange of nuclear safety information is being established by the US Nuclear Regulatory Commission. For developing countries such arrangements can provide ready access to the extensive, fully documented safety analyses and safety research results that USNRC has accumulated. USNRC has been receiving foreign visitors at a rate of about 500 per year, largely for discussions of safety and licensing questions related to light water reactors. Exchanges also are taking place on the safety of advanced reactors. A special interest of the USNRC is in providing for reciprocal communication, at the earliest possible time, of important problems, decisions and other actions on nuclear safety matters. For example, it is essential that a newly discovered problem in a nuclear reactor be brought immediately to the attention of other governments that are responsible for the safety of similar reactors. Definite progress has been made in the USA in defining categories of information that USNRC can receive in confidence from foreign countries, and can protect from disclosure under the US Freedom of Information Act. Certain exchanges have taken place on this basis. Experience in the establishment and operation of USNRC's bilateral exchange arrangements is summarized. A typical exchange with the regulatory authority of a country building its first power reactor is described. (author)

  14. International exchange of safety and licensing information

    International Nuclear Information System (INIS)

    Lafleur, J.D. Jr.; Hauber, R.D.; Chenier, D.M.

    1977-01-01

    A network of formal and informal bilateral arrangements for the exchange of nuclear safety information is being established by the U.S. Nuclear Regulatory Commission. For developing countries, such arrangements can provide ready access to the extensive, fully documented safety analyses and safety research results that NRC has accumulated. NRC has been receiving foreign visitors at a rate of about 500 per year, largely for discussions of safety and licensing questions related to light water reactors. Exchanges also are taking place on the safety of advanced reactors. A special interest of the NRC is in providing for reciprocal communicaion, at the earliest possible time, of important problems, decisions and other actions on nuclear safety matters. For example, it is essential that a newly-discovered problem in a nuclear reactor be brought immediately to the attention of other governments which are responsible for the safety of similar reactors. Definite progress has been made in the U.S. Freedom of Information Act. Certain exchanges have taken place on this basis. Experience in the establishment and operation of NRC's bilateral exchange arrangements is summarized. A typical exchange with the regulatory authority of country building its first power reactor is described

  15. Production bias and cluster annihilation: Why necessary?

    DEFF Research Database (Denmark)

    Singh, B.N.; Trinkaus, H.; Woo, C.H.

    1994-01-01

    the primary cluster density is high. Therefore, a sustained high swelling rate driven by production bias must involve the annihilation of primary clusters at sinks. A number of experimental observations which are unexplainable in terms of the conventional dislocation bias for monointerstitials is considered....... It is found that the production bias and cluster annihilation are necessary to explain these observations, with, in many cases, the explicit consideration of the annihilation of the primary interstitial clusters....

  16. Establishing effective working relationships.

    Science.gov (United States)

    Houghton, Trish

    2016-02-24

    This article, the second in a series of 11, provides support and offers advice to new and existing mentors and practice teachers to enable them to progress in their role and develop a portfolio of evidence. In particular, the article discusses how to establish effective working relationships and emphasises the importance of the student-mentor or student-practice teacher relationship. It examines the essential qualities, attributes and characteristics of an effective mentor or practice teacher. The article provides learning activities and suggests ways in which mentors and practice teachers can undertake various self-assessments, enabling them to gather relevant evidence to demonstrate how they can meet and maintain the requirements for these roles as stipulated by the Nursing and Midwifery Council.

  17. Establishing Political Deliberation Systems

    DEFF Research Database (Denmark)

    Rose, Jeremy; Sæbø, Øystein

    2008-01-01

    The extension and transformation of political participation is dependent on widespread deliberation supported by information and communication technologies.  The most commonly found examples of these eParticipation systems are political discussion forums.  Though much of the discussion...... of these technologies is conducted in the eGovernment and (particularly) the eDemocracy literature, political discussion forums present a distinct set of design and management challenges which relate directly to IS concerns. In this article we analyze problems in establishing political deliberation systems under five...... headings: stakeholder engagement, web platform design, web platform management, political process re-shaping and evaluation and improvement. We review the existing literature and present a longitudinal case study of a political discussion forum: the Norwegian DemokratiTorget (Democracy Square).  We define...

  18. Attribution bias and social anxiety in schizophrenia

    Directory of Open Access Journals (Sweden)

    Amelie M. Achim

    2016-06-01

    Full Text Available Studies on attribution biases in schizophrenia have produced mixed results, whereas such biases have been more consistently reported in people with anxiety disorders. Anxiety comorbidities are frequent in schizophrenia, in particular social anxiety disorder, which could influence their patterns of attribution biases. The objective of the present study was thus to determine if individuals with schizophrenia and a comorbid social anxiety disorder (SZ+ show distinct attribution biases as compared with individuals with schizophrenia without social anxiety (SZ− and healthy controls. Attribution biases were assessed with the Internal, Personal, and Situational Attributions Questionnaire in 41 individual with schizophrenia and 41 healthy controls. Results revealed the lack of the normal externalizing bias in SZ+, whereas SZ− did not significantly differ from healthy controls on this dimension. The personalizing bias was not influenced by social anxiety but was in contrast linked with delusions, with a greater personalizing bias in individuals with current delusions. Future studies on attribution biases in schizophrenia should carefully document symptom presentation, including social anxiety.

  19. Real Exchange Rates in Advanced Transition Economies

    Directory of Open Access Journals (Sweden)

    Sanja Grubacic

    2015-10-01

    Full Text Available The recent evidence from Eastern Europe suggests that one of the major obstacles towards the adoption of euro may lie in the impact that the recession of 2008 exerted on the trajectory of real exchange rates in new member countries (European Commission, 2015.  This paper aims to establish and explain the relationship between the external shocks derived from the global financial crisis and recession of 2008 and equilibrium real exchange rate in advanced transition economies of Eastern Europe. The interplay between the external and internal balances is explained by developing an inter-temporal optimizing model of the real exchange rate determination in a small open economy with structural distortions. The results of our model suggest that, in the aftermath of recession, if the Eastern European economies attempt to restore and maintain the balance between the consumption, saving, and investment, the equilibrium real exchange rate will tend to reverse its trajectory from appreciation to depreciation over time in order to encourage a greater production in the future. The equilibrium real exchange rate depreciation in the future may obtain either as a result of an increase in the direct subsidies on investment or as a result of reduced subsidies on the "net-of-investment" income.  The deprecation of countries’ real exchange rate, however, may continue to act as an effective constraint against the adoption of euro.

  20. Who are you expecting? Biases in face perception reveal prior expectations for sex and age.

    Science.gov (United States)

    Watson, Tamara Lea; Otsuka, Yumiko; Clifford, Colin Walter Giles

    2016-01-01

    A person's appearance contains a wealth of information, including indicators of their sex and age. Because first impressions can set the tone of subsequent relationships, it is crucial we form an accurate initial impression. Yet prior expectation can bias our decisions: Studies have reported biases to respond "male" when asked to report a person's sex from an image of their face and to place their age closer to their own. Perceptual expectation effects and cognitive response biases may both contribute to these inaccuracies. The current research used a Bayesian modeling approach to establish the perceptual biases involved when estimating the sex and age of an individual from their face. We demonstrate a perceptual bias for male and older faces evident under conditions of uncertainty. This suggests the well-established male bias is perceptual in origin and may be impervious to cognitive control. In comparison, the own age anchor effect is not operationalized at the perceptual level: The perceptual expectation is for a face of advanced age. Thus, distinct biases in the estimation of age operate at the perceptual and cognitive levels.

  1. Wound tube heat exchanger

    Science.gov (United States)

    Ecker, Amir L.

    1983-01-01

    What is disclosed is a wound tube heat exchanger in which a plurality of tubes having flattened areas are held contiguous adjacent flattened areas of tubes by a plurality of windings to give a double walled heat exchanger. The plurality of windings serve as a plurality of effective force vectors holding the conduits contiguous heat conducting walls of another conduit and result in highly efficient heat transfer. The resulting heat exchange bundle is economical and can be coiled into the desired shape. Also disclosed are specific embodiments such as the one in which the tubes are expanded against their windings after being coiled to insure highly efficient heat transfer.

  2. Heat and mass exchanger

    Science.gov (United States)

    Lowenstein, Andrew; Sibilia, Marc J.; Miller, Jeffrey A.; Tonon, Thomas

    2007-09-18

    A mass and heat exchanger includes at least one first substrate with a surface for supporting a continuous flow of a liquid thereon that either absorbs, desorbs, evaporates or condenses one or more gaseous species from or to a surrounding gas; and at least one second substrate operatively associated with the first substrate. The second substrate includes a surface for supporting the continuous flow of the liquid thereon and is adapted to carry a heat exchange fluid therethrough, wherein heat transfer occurs between the liquid and the heat exchange fluid.

  3. Biases in the production and reception of collective knowledge: the case of hindsight bias in Wikipedia.

    Science.gov (United States)

    Oeberst, Aileen; von der Beck, Ina; D Back, Mitja; Cress, Ulrike; Nestler, Steffen

    2017-04-17

    The Web 2.0 enabled collaboration at an unprecedented level. In one of the flagships of mass collaboration-Wikipedia-a large number of authors socially negotiate the world's largest compendium of knowledge. Several guidelines in Wikipedia restrict contributions to verifiable information from reliable sources to ensure recognized knowledge. Much psychological research demonstrates, however, that individual information processing is biased. This poses the question whether individual biases translate to Wikipedia articles or whether they are prevented by its guidelines. The present research makes use of hindsight bias to examine this question. To this end, we analyzed foresight and hindsight versions of Wikipedia articles regarding a broad variety of events (Study 1). We found the majority of articles not to contain traces of hindsight bias-contrary to prior individual research. However, for a particular category of events-disasters-we found robust evidence for hindsight bias. In a lab experiment (Study 2), we then examined whether individuals' hindsight bias is translated into articles under controlled conditions and tested whether collaborative writing-as present in Wikipedia-affects the resultant bias (vs. individual writing). Finally, we investigated the impact of biased Wikipedia articles on readers (Study 3). As predicted, biased articles elicited a hindsight bias in readers, who had not known of the event previously. Moreover, biased articles also affected individuals who knew about the event already, and who had already developed a hindsight bias: biased articles further increased their hindsight.

  4. Method for removing atomic-model bias in macromolecular crystallography

    Science.gov (United States)

    Terwilliger, Thomas C [Santa Fe, NM

    2006-08-01

    Structure factor bias in an electron density map for an unknown crystallographic structure is minimized by using information in a first electron density map to elicit expected structure factor information. Observed structure factor amplitudes are combined with a starting set of crystallographic phases to form a first set of structure factors. A first electron density map is then derived and features of the first electron density map are identified to obtain expected distributions of electron density. Crystallographic phase probability distributions are established for possible crystallographic phases of reflection k, and the process is repeated as k is indexed through all of the plurality of reflections. An updated electron density map is derived from the crystallographic phase probability distributions for each one of the reflections. The entire process is then iterated to obtain a final set of crystallographic phases with minimum bias from known electron density maps.

  5. Hadron spectroscopy in double pomeron exchange experiments

    Science.gov (United States)

    Albrow, Michael G.

    2017-03-01

    Central exclusive production in hadron-hadron collisions at high energies, for example p + p → p + X + p, where the + represents a large rapidity gap, is a valuable process for spectroscopy of mesonic states X. At collider energies the gaps can be large enough to be dominated by pomeron exchange, and then the quantum numbers of the state X are restricted. Isoscalar JPC = 0++ and 2++ mesons are selected, and our understanding of these spectra is incomplete. In particular, soft pomeron exchanges favor gluon-dominated states such as glueballs, which are expected in QCD but not yet well established. I will review some published data.

  6. Hadron Spectroscopy in Double Pomeron Exchange Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Albrow, Michael [Fermilab

    2016-11-15

    Central exclusive production in hadron-hadron collisions at high energies, for example p + p -> p + X + p, where the "+" represents a large rapidity gap, is a valuable process for spectroscopy of mesonic states X. At collider energies the gaps can be large enough to be dominated by pomeron exchange, and then the quantum numbers of the state X are restricted. Isoscalar JPC = 0++ and 2++ mesons are selected, and our understanding of these spectra is incomplete. In particular, soft pomeron exchanges favor gluon-dominated states such as glueballs, which are expected in QCD but not yet well established. I will review some published data.

  7. Spatial bias in estimating the position of visual and proprioceptive targets.

    Science.gov (United States)

    Liu, Yang; Sexton, Brandon Montgomery; Block, Hannah J

    2018-02-21

    When people match an unseen hand to a visual or proprioceptive target, they make both variable and systematic (bias) errors. Variance is a well-established factor in behavior, but the origin and implications of bias, and its connection to variance, are poorly understood. Eighty healthy adults matched their unseen right index finger to proprioceptive (left index finger) and visual targets with no performance feedback. We asked whether matching bias was related to target modality and to the magnitude or spatial properties of matching variance. Bias errors were affected by target modality, with subjects estimating visual and proprioceptive targets 20 mm apart. We found three pieces of evidence to suggest a connection between bias and variable errors: (1) for most subjects, the target modality that yielded greater spatial bias was also estimated with greater variance; (2) magnitudes of matching bias and variance were somewhat correlated for each target modality (R = 0.24 and 0.29); and (3), bias direction was closely related to the angle of the major axis of the confidence ellipse (R = 0.60 and 0.63). However, while variance was significantly correlated with visuo-proprioceptive weighting as predicted by multisensory integration theory (R = -0.29 and 0.27 for visual and proprioceptive variance, respectively), bias was not. In a second session, subjects improved their matching variance, but not bias, for both target modalities, indicating a difference in stability. Taken together, these results suggest bias and variance are related only in some respects, which should be considered in the study of multisensory behavior.

  8. Do anxious parents interpretive biases towards threat extend into their child's environment?

    Science.gov (United States)

    Lester, Kathryn J; Field, Andy P; Oliver, Samantha; Cartwright-Hatton, Sam

    2009-02-01

    Anxiety disorders are known to run in families [Turner, S. M., Beidel, D. C., & Costello, A. (1987). Psychopathology in the offspring of anxiety disorder patients. Journal of Consulting and Clinical Psychology, 55(2), 229-235] and environmental factors may largely account for the concordance between parental and child anxieties. Cognitive psychology models emphasise the importance of interpretive biases towards threat in the maintenance of anxiety and it is well established that anxious adults and children display similar interpretive biases and that these biases in anxious parents and their children are correlated. This raises the question of whether anxious cognitions/cognitive style may be transmitted from parent to child. We propose that this is more likely if anxious parents demonstrate interpretive biases not only about potential threats in their own environment but also about potential threats in their child's environment. Forty parents completed a recognition memory measure of interpretation bias adapted from Eysenck, Mogg, May, Richards, and Mathews (1991) [Bias in interpretation of ambiguous sentences related to threat in anxiety. Journal of Abnormal Psychology, 100(2), 144-150] to measure biases in response to potentially threat provoking situations involving themselves and their child. The interpretive biases demonstrated by parents were similar across situations involving themselves and their children. As expected, parental interpretive biases were further modified by anxiety with higher levels of parental anxiety associated with more negative interpretive biases about situations in their own and their child's environment, although this association was significantly stronger for potentially threat provoking situations in their own environment. These results are consistent with parent's interpretive biases extending beyond their own environment into their child's environment, although future research should continue to consider the mechanisms by which

  9. Preference-driven biases in decision makers' information search and evaluation

    Directory of Open Access Journals (Sweden)

    Anne-Sophie Chaxel

    2013-09-01

    Full Text Available While it is well established that the search for information after a decision is biased toward supporting that decision, the case of preference-supporting search before the decision remains open. Three studies of consumer choices consistently found a complete absence of a pre-choice bias toward searching for preference-supporting information. The absence of this confirming search bias occurred for products that were both hedonic and utilitarian, both expensive and inexpensive, and both high and low in expected brand loyalty. Experiment 3 also verified the presence of the expected post-choice search bias to support the chosen alternative. Therefore the absence of a pre-choice search bias in all three studies was not likely to be due to our using a method that was so insensitive that a search bias would not be observed under any circumstances. In addition to the absence of an effect of prior preferences on information selection, subjects' self-reported search strategies exhibited a clear tendency toward a balance of positive and negative information. Across the three studies, we also tested for the presence of a preference-supporting bias in the evaluation of the information acquired in the search process. This evaluation bias was found both pre- and post-choice.

  10. Risoe Research Establishment, Denmark

    International Nuclear Information System (INIS)

    1973-01-01

    On the poetic Roskilde Fjord, 40 kilometers from Copenhagen, and near Roskilde, capital of Denmark in the 12th century, stands the Risoe Research Establishment of the Danish Atomic Energy Commission. ere 700 men and women are engaged in searching for ways in which atomic energy can be used to make the world a better and healthier place. The work at Risoe comprises fundamental research, reactor technology and other technological studies, agricultural research and health and safety studies. Nuclear power stations are scheduled to be operative in Denmark some time between 1975 and 1980, and the planning of these stations and development of the many processes this will involve has become a major task at Risoe. Special conditions have to be fulfilled in selecting the site of an atomic research station, and the barren Risoe peninsula had them all: safety, because the site was free from buildings to permit continuous control; closeness to the scientific institutions of the capital, Copenhagen; social amenities in Roskilde; finally, access to an a adequate water supply. his special series of photos covering some aspects of the work and safety conditions at Risoe was commissioned by WHO. (author)

  11. Data Exchange Inventory System (DEXI)

    Data.gov (United States)

    Social Security Administration — Enterprise tool used to identify data exchanges occurring between SSA and our trading partners. DEXI contains information on both incoming and outgoing exchanges and...

  12. NASA Earth Exchange (NEX)

    Data.gov (United States)

    National Aeronautics and Space Administration — The NASA Earth Exchange (NEX) represents a new platform for the Earth science community that provides a mechanism for scientific collaboration and knowledge sharing....

  13. Research peer exchange, 2014.

    Science.gov (United States)

    2017-08-01

    The WSDOT Research Peer Exchange was held in Olympia, Washington on May 13 and 14, 2014 and addressed Research Program and Project Management as described in the following paragraphs: Program Management There are numerous funding programs, standing c...

  14. Cation Exchange Water Softeners

    Science.gov (United States)

    WaterSense released a notice of intent to develop a specification for cation exchange water softeners. The program has made the decision not to move forward with a spec at this time, but is making this information available.

  15. Active microchannel heat exchanger

    Science.gov (United States)

    Tonkovich, Anna Lee Y [Pasco, WA; Roberts, Gary L [West Richland, WA; Call, Charles J [Pasco, WA; Wegeng, Robert S [Richland, WA; Wang, Yong [Richland, WA

    2001-01-01

    The present invention is an active microchannel heat exchanger with an active heat source and with microchannel architecture. The microchannel heat exchanger has (a) an exothermic reaction chamber; (b) an exhaust chamber; and (c) a heat exchanger chamber in thermal contact with the exhaust chamber, wherein (d) heat from the exothermic reaction chamber is convected by an exothermic reaction exhaust through the exhaust chamber and by conduction through a containment wall to the working fluid in the heat exchanger chamber thereby raising a temperature of the working fluid. The invention is particularly useful as a liquid fuel vaporizer and/or a steam generator for fuel cell power systems, and as a heat source for sustaining endothermic chemical reactions and initiating exothermic reactions.

  16. HUD Exchange Grantee Database

    Data.gov (United States)

    Department of Housing and Urban Development — The About Grantees section of the HUD Exchange brings up contact information, reports, award, jurisdiction, and location data for organizations that receive HUD...

  17. Exchange transfusion - slideshow

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/presentations/100018.htm Exchange transfusion - series—Procedure To use the sharing features on ... M. Editorial team. Related MedlinePlus Health Topics Blood Transfusion and Donation Common Infant and Newborn Problems Jaundice ...

  18. Exchange Risk Management Policy

    CERN Document Server

    2005-01-01

    At the Finance Committee of March 2005, following a comment by the CERN Audit Committee, the Chairman invited the Management to prepare a document on exchange risk management policy. The Finance Committee is invited to take note of this document.

  19. Media bias under direct and indirect government control: when is the bias smaller?

    OpenAIRE

    Abhra Roy

    2015-01-01

    We present an analytical framework to compare media bias under direct and indirect government control. In this context, we show that direct control can lead to a smaller bias and higher welfare than indirect control. We further show that the size of the advertising market affects media bias only under direct control. Media bias, under indirect control, is not affected by the size of the advertising market.

  20. Contact Heat Exchanger

    Science.gov (United States)

    Fleming, M. L.; Stalmach, D. D.; Cox, R. L.

    1985-01-01

    Fluid pressure controls contact between heat pipe and heat exchanger. Heat exchanger system in cross section provides contact interface between fluid system and heat pipe with easy assembly/disassembly of heat-pipe/ pumped-liquid system. Originally developed for use in space, new device applicable on Earth where fluid system is linked with heat pipe, where rapid assembly/disassembly required, or where high pressures or corrosive fluids used.

  1. Hibernation and gas exchange.

    Science.gov (United States)

    Milsom, William K; Jackson, Donald C

    2011-01-01

    Hibernation in endotherms and ectotherms is characterized by an energy-conserving metabolic depression due to low body temperatures and poorly understood temperature-independent mechanisms. Rates of gas exchange are correspondly reduced. In hibernating mammals, ventilation falls even more than metabolic rate leading to a relative respiratory acidosis that may contribute to metabolic depression. Breathing in some mammals becomes episodic and in some small mammals significant apneic gas exchange may occur by passive diffusion via airways or skin. In ectothermic vertebrates, extrapulmonary gas exchange predominates and in reptiles and amphibians hibernating underwater accounts for all gas exchange. In aerated water diffusive exchange permits amphibians and many species of turtles to remain fully aerobic, but hypoxic conditions can challenge many of these animals. Oxygen uptake into blood in both endotherms and ectotherms is enhanced by increased affinity of hemoglobin for O₂ at low temperature. Regulation of gas exchange in hibernating mammals is predominately linked to CO₂/pH, and in episodic breathers, control is principally directed at the duration of the apneic period. Control in submerged hibernating ectotherms is poorly understood, although skin-diffusing capacity may increase under hypoxic conditions. In aerated water blood pH of frogs and turtles either adheres to alphastat regulation (pH ∼8.0) or may even exhibit respiratory alkalosis. Arousal in hibernating mammals leads to restoration of euthermic temperature, metabolic rate, and gas exchange and occurs periodically even as ambient temperatures remain low, whereas body temperature, metabolic rate, and gas exchange of hibernating ectotherms are tightly linked to ambient temperature. © 2011 American Physiological Society.

  2. Real exchange rate misalignments

    OpenAIRE

    Terra, Maria Cristina T.; Valladares, Frederico Estrella Carneiro

    2003-01-01

    This paper characterizes episodes of real appreciations and depreciations for a sample of 85 countries, approximately from 1960 to 1998. First, the equilibrium real exchange rate series are constructed for each country using Goldfajn and Valdes (1999) methodology (cointegration with fundamentals). Then, departures from equilibrium real exchange rate (misalignments) are obtained, and a Markov Switching Model is used to characterize the misalignments series as stochastic autor...

  3. Heat exchanger cleaning

    International Nuclear Information System (INIS)

    Gatewood, J.R.

    1980-01-01

    A survey covers the various types of heat-exchange equipment that is cleaned routinely in fossil-fired generating plants, the hydrocarbon-processing industry, pulp and paper mills, and other industries; the various types, sources, and adverse effects of deposits in heat-exchange equipment; some details of the actual procedures for high-pressure water jetting and chemical cleaning of some specific pieces of equipment, including nuclear steam generators. (DN)

  4. Outline for the establishment of an orderly coal trade market

    International Nuclear Information System (INIS)

    Murai, S.

    1988-01-01

    This paper reports on the present situation of the coal trade market. It discusses the changes in the coal trade market, the present situation of the coal trade in Japan, supply trends, demand trends and fluctuation of exchange rates. This paper also reports on the problems associated with establishing an orderly coal trade market by the examination of contract form, development of coal technology to expand coal use, cooperation with developing countries and creating a new coal market by establishing a coal complex

  5. Biased trapping issue on weighted hierarchical networks

    Indian Academy of Sciences (India)

    In this paper, we present trapping issues of weight-dependent walks on weighted hierarchical networks which are based on the classic scale-free hierarchical networks. Assuming that edge's weight is used as local information by a random walker, we introduce a biased walk. The biased walk is that a walker, at each step, ...

  6. Reducing status quo bias in choice experiments

    DEFF Research Database (Denmark)

    Bonnichsen, Ole; Ladenburg, Jacob

    In stated preference literature, the tendency to choose the alternative representing the status quo situation seems to exceed real life status quo effects. Accordingly, status quo bias can be a problem. In Choice Experiments, status quo bias is found to be strongly correlated with protest attitudes...

  7. Reducing status quo bias in choice experiments

    DEFF Research Database (Denmark)

    Bonnichsen, Ole; Ladenburg, Jacob

    2015-01-01

    to be superior, i.e. a status quo effect. However, in the stated preference literature, the tendency to choose the alternative representing the status quo situation seems to exceed real life status quo effects. Accordingly, status quo bias can be a problem. In the Choice Experiment literature, status quo bias...

  8. Racially Biased Policing: Determinants of Citizen Perceptions

    Science.gov (United States)

    Weitzer, Ronald; Tuch, Steven A.

    2005-01-01

    The current controversy surrounding racial profiling in America has focused renewed attention on the larger issue of racial bias by the police. Yet little is known about the extent of police racial bias and even less about public perceptions of the problem. This article analyzes recent national survey data on citizens' views of and reported…

  9. Monotheism versus an innate bias towards mentalizing.

    Science.gov (United States)

    Costello, Fintan John

    2016-01-01

    Norenzayan et al.'s account for the spread of monotheistic "Big God" religions sees these religions originating as by-products of innate cognitive biases. These biases produce polytheistic rather than monotheistic systems, however, and so do not explain the origin of monotheism. Accounts where monotheism arises from polytheism (for political reasons, for example) appear better able to explain the spread of monotheism.

  10. Bias-correction in vector autoregressive models

    DEFF Research Database (Denmark)

    Engsted, Tom; Pedersen, Thomas Quistgaard

    2014-01-01

    We analyze the properties of various methods for bias-correcting parameter estimates in both stationary and non-stationary vector autoregressive models. First, we show that two analytical bias formulas from the existing literature are in fact identical. Next, based on a detailed simulation study...

  11. Attention bias modification: the Emperor's new suit?

    NARCIS (Netherlands)

    Emmelkamp, P.M.G.

    2012-01-01

    A series of primarily laboratory-based studies found attention bias modification in socially anxious participants to lead to reduced anxiety. It is argued that the failure to replicate the positive results of attention bias modification in the study of Carlbring et al. may be due to reasons other

  12. Developmental Changes in the Whole Number Bias

    Science.gov (United States)

    Braithwaite, David W.; Siegler, Robert S.

    2018-01-01

    Many students' knowledge of fractions is adversely affected by whole number bias, the tendency to focus on the separate whole number components (numerator and denominator) of a fraction rather than on the fraction's magnitude (ratio of numerator to denominator). Although whole number bias appears early in the fraction learning process and under…

  13. Dialogue Games for Inconsistent and Biased Information

    NARCIS (Netherlands)

    Lebbink, H.J.; Witteman, C.L.M.; Meyer, J.J.C.

    2003-01-01

    In this article, a dialogue game is presented in which coherent conversational sequences with inconsistent and biased information are described at the speech act level. Inconsistent and biased information is represented with bilattice structures, and based on these bilattice structures, a

  14. Adjusting the Interview to Avoid Cultural Bias.

    Science.gov (United States)

    Mahoney, Frances Eileen

    1992-01-01

    Considers cultural bias in employment interviews. Compares white American and Navajo interview styles and suggests new approach for recruiters to make interviewing less culturally biased. Recommends that recruiters not ask direct questions about personal achievements, try indirect approach, avoid making judgments on first impressions and…

  15. EVIDENCE OF NATIONALISTIC BIAS IN MUAYTHAI

    Directory of Open Access Journals (Sweden)

    Tony D. Myers

    2006-07-01

    Full Text Available MuayThai is a combat sport with a growing international profile but limited research conducted into judging practices and processes. Problems with judging of other subjectively judged combat sports have caused controversy at major international tournaments that have resulted in changes to scoring methods. Nationalistic bias has been central to these problems and has been identified across a range of sports. The aim of this study was to examine nationalistic bias in MuayThai. Data were collected from the International Federation of MuayThai Amateur (IFMA World Championships held in Almaty, Kazakhstan September 2003 and comprised of tournament results from 70 A-class MuayThai bouts each judged by between five and nine judges. Bouts examined featured 62 competitors from 21 countries and 25 judges from 11 countries. Results suggested that nationalistic bias was evident. The bias observed equated to approximately one round difference between opposing judges over the course of a bout (a mean of 1.09 (SE=0.50 points difference between judges with opposing affilations. The number of neutral judges used meant that this level of bias generally did not influence the outcome of bouts. Future research should explore other ingroup biases, such as nearest neighbour bias and political bias as well as investigating the feasibility adopting an electronic scoring system

  16. Distinctive Characteristics of Sexual Orientation Bias Crimes

    Science.gov (United States)

    Stacey, Michele

    2011-01-01

    Despite increased attention in the area of hate crime research in the past 20 years, sexual orientation bias crimes have rarely been singled out for study. When these types of crimes are looked at, the studies are typically descriptive in nature. This article seeks to increase our knowledge of sexual orientation bias by answering the question:…

  17. Gender Bias: Inequities in the Classroom.

    Science.gov (United States)

    Love, Reeve

    1993-01-01

    This article explores sex bias in curricular materials for elementary and secondary schools. Sex bias is defined as a set of unconscious behaviors that, in themselves, are often trivial and generally favorable. Although these behaviors do not hurt if they happen only once, they can cause a great deal of harm if a pattern develops that serves to…

  18. The Battle over Studies of Faculty Bias

    Science.gov (United States)

    Gravois, John

    2007-01-01

    The American Federation of Teachers (AFT) recently commissioned a study to review the research that finds liberal bias run amok in academe. Believing that the AFT is not a dispassionate observer of this debate, this article provides "The Chronicle of Higher Education's" survey of the genre. The studies reviewed include: (1) "Political Bias in the…

  19. Radial flow heat exchanger

    Science.gov (United States)

    Valenzuela, Javier

    2001-01-01

    A radial flow heat exchanger (20) having a plurality of first passages (24) for transporting a first fluid (25) and a plurality of second passages (26) for transporting a second fluid (27). The first and second passages are arranged in stacked, alternating relationship, are separated from one another by relatively thin plates (30) and (32), and surround a central axis (22). The thickness of the first and second passages are selected so that the first and second fluids, respectively, are transported with laminar flow through the passages. To enhance thermal energy transfer between first and second passages, the latter are arranged so each first passage is in thermal communication with an associated second passage along substantially its entire length, and vice versa with respect to the second passages. The heat exchangers may be stacked to achieve a modular heat exchange assembly (300). Certain heat exchangers in the assembly may be designed slightly differently than other heat exchangers to address changes in fluid properties during transport through the heat exchanger, so as to enhance overall thermal effectiveness of the assembly.

  20. Childhood obesity: issues of weight bias.

    Science.gov (United States)

    Washington, Reginald L

    2011-09-01

    Although the effects of obesity on children's physical health are well documented, the social consequences of obesity are less well described and may not be addressed in intervention programs. Weight bias may take several forms. It may result in teasing and discrimination and may affect employment and educational opportunities. Health care providers may limit care of overweight or obese children. The media promote weight bias in multiple ways. Some parents are biased against their obese children. In an effort to avoid weight bias, new efforts to reduce obesity must be evaluated to determine whether these efforts do, in fact, add to the problem. It is important to understand that the weight bias that obese youth face is just as serious as the physical consequences of excessive weight on the welfare of the child.

  1. Medical journal peer review: process and bias.

    Science.gov (United States)

    Manchikanti, Laxmaiah; Kaye, Alan D; Boswell, Mark V; Hirsch, Joshua A

    2015-01-01

    Scientific peer review is pivotal in health care research in that it facilitates the evaluation of findings for competence, significance, and originality by qualified experts. While the origins of peer review can be traced to the societies of the eighteenth century, it became an institutionalized part of the scholarly process in the latter half of the twentieth century. This was a response to the growth of research and greater subject specialization. With the current increase in the number of specialty journals, the peer review process continues to evolve to meet the needs of patients, clinicians, and policy makers. The peer review process itself faces challenges. Unblinded peer review might suffer from positive or negative bias towards certain authors, specialties, and institutions. Peer review can also suffer when editors and/or reviewers might be unable to understand the contents of the submitted manuscript. This can result in an inability to detect major flaws, or revelations of major flaws after acceptance of publication by the editors. Other concerns include potentially long delays in publication and challenges uncovering plagiarism, duplication, corruption and scientific misconduct. Conversely, a multitude of these challenges have led to claims of scientific misconduct and an erosion of faith. These challenges have invited criticism of the peer review process itself. However, despite its imperfections, the peer review process enjoys widespread support in the scientific community. Peer review bias is one of the major focuses of today's scientific assessment of the literature. Various types of peer review bias include content-based bias, confirmation bias, bias due to conservatism, bias against interdisciplinary research, publication bias, and the bias of conflicts of interest. Consequently, peer review would benefit from various changes and improvements with appropriate training of reviewers to provide quality reviews to maintain the quality and integrity of

  2. 76 FR 5412 - Self-Regulatory Organizations; International Securities Exchange, LLC; Notice of Filing of...

    Science.gov (United States)

    2011-01-31

    ... Organizations; International Securities Exchange, LLC; Notice of Filing of Proposed Rule Change To Establish a New Class of Market Participant for Index Options January 25, 2011. Pursuant to Section 19(b)(1) of... given that on January 12, 2011, International Securities Exchange, LLC (the ``Exchange'' or the ``ISE...

  3. Hidden Interface Driven Exchange Coupling in Oxide Heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Aiping [Center for Integrated Nanotechnologies (CINT), Los Alamos National Laboratory, Los Alamos NM 87545 USA; Wang, Qiang [Materials Science Division, Argonne National Laboratory, Argonne IL 60439 USA; Department of Physics and Astronomy, West Virginia University, Morgantown WV 26506 USA; Fitzsimmons, Michael R. [Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge TN 37831 USA; Department of Physics and Astronomy, University of Tennessee, Knoxville TN 37996 USA; Enriquez, Erik [Center for Integrated Nanotechnologies (CINT), Los Alamos National Laboratory, Los Alamos NM 87545 USA; Weigand, Marcus [Center for Integrated Nanotechnologies (CINT), Los Alamos National Laboratory, Los Alamos NM 87545 USA; Harrell, Zach [Center for Integrated Nanotechnologies (CINT), Los Alamos National Laboratory, Los Alamos NM 87545 USA; McFarland, Brian [Center for Integrated Nanotechnologies (CINT), Los Alamos National Laboratory, Los Alamos NM 87545 USA; Lü, Xujie [Center for Integrated Nanotechnologies (CINT), Los Alamos National Laboratory, Los Alamos NM 87545 USA; Dowden, Paul [Center for Integrated Nanotechnologies (CINT), Los Alamos National Laboratory, Los Alamos NM 87545 USA; MacManus-Driscoll, Judith L. [Department of Materials Science, University of Cambridge, Cambridge CB3 OFS UK; Yarotski, Dmitry [Center for Integrated Nanotechnologies (CINT), Los Alamos National Laboratory, Los Alamos NM 87545 USA; Jia, Quanxi [Center for Integrated Nanotechnologies (CINT), Los Alamos National Laboratory, Los Alamos NM 87545 USA; Department of Materials Design and Innovation, University at Buffalo - The State University of New York, Buffalo NY 14260 USA

    2017-05-02

    A variety of emergent phenomena have been enabled by interface engineering in complex oxides. The existence of an intrinsic interfacial layer has often been found at oxide heterointerfaces. However, the role of such an interlayerin controlling functionalities is not fully explored. Here, we report the control of the exchange bias (EB) in single-phase manganite thin films with nominallyuniform chemical composition across the interfaces. The sign of EB depends on the magnitude of the cooling field. A pinned layer, confirmed by polarized neutron reflectometry, provides the source of unidirectional anisotropy. The origin of the exchange bias coupling is discussed in terms of magnetic interactions between the interfacial ferromagnetically reduced layer and the bulk ferromagnetic region. The sign of EB is related to the frustration of antiferromagnetic coupling between the ferromagnetic region and the pinned layer. Our results shed new light on using oxide interfaces to design functional spintronic devices.

  4. Apparatus for concentrating by dual temperature exchange

    International Nuclear Information System (INIS)

    Spevack, J.S.

    1975-01-01

    The dual temperature exchange apparatus, with a dual temperature stage having a hot processing tower and a cold processing tower, is provided with means for transferring heat from the hot processed gas to both liquid and gas being delivered to the hot processing tower. The heat exchange system provides means for effecting direct contact between the hot processed gas and the cold processed liquid being delivered to the hot tower, means for establishing a circulation of the resulting heated processed liquid, and means including an indirect contact exchanger for transferring heat from said circulation to condition the gas being supplied to the hot processing tower. The reactants in the example given are hydrogen sulfide gas and liquid water

  5. Signatures of asymmetric and inelastic tunneling on the spin torque bias dependence

    KAUST Repository

    Manchon, Aurelien

    2010-11-15

    The influence of structural asymmetries (barrier height and exchange splitting), as well as inelastic scattering (magnons and phonons) on the bias dependence of the spin transfer torque in a magnetic tunnel junction is studied theoretically using the free-electron model. We show that they modify the “conventional” bias dependence of the spin transfer torque, together with the bias dependence of the conductance. In particular, both structural asymmetries and bulk (inelastic) scattering add antisymmetric terms to the perpendicular torque (∝V and ∝je|V|) while the interfacial inelastic scattering conserves the junction symmetry and only produces symmetric terms (∝|V|n, n∊N). The analysis of spin torque and conductance measurements displays a signature revealing the origin (asymmetry or inelastic scattering) of the discrepancy.

  6. Tensor exchange amplitudes in K +- N charge exchange reactions

    International Nuclear Information System (INIS)

    Svec, M.

    1979-01-01

    Tensor (A 2 ) exchange amplitudes in K +- N charge exchange (CEX) are constructed from the K +- N CEX data supplemented by information on the vector (rho) exchange amplitudes from πN sca tering. We observed new features in the t-structure of A 2 exchange amplitudes which contradict the t-de pendence anticipated by most of the Regge models. The results also provide evidence for violation of weak exchange degeneracy

  7. Gender bias in acute coronary syndromes.

    Science.gov (United States)

    Bugiardini, Raffaele; Estrada, Jose L Navarro; Nikus, Kjell; Hall, Alistair S; Manfrini, Olivia

    2010-03-01

    The major aim of this review was to ascertain whether effective evidence-based treatments for acute coronary syndromes (ACS) are underutilized in women in various geographic areas compared with men. The focus of our review was the relative use of effective treatments in patients with coronary angiographic evidence of obstructive coronary disease, defined as a lumen stenosis >50% of the adjacent non-diseased arterial diameter. We searched MEDLINE, and the Cochrane Database between January 1998 and May 2008. Only a few of the published clinical registries on ACS provide data on treatments dichotomized by confirmed coronary angiographic disease. Consequently, we also accessed individual patient-level data from 3 established ACS registries: the Finnish TACOS (Tampere Acute COronary Syndrome), the British EMMACE 2 (Evaluation of Methods and Management of Acute Coronary Events) and the Argentine PACS-ITALSIA (Prognosis in Acute Coronary Syndromes and the ITALian hospital Sindrome Isquemico Agudo). Despite presenting with higher risk characteristics and having higher in-hospital and 6 months risk of death, women with ACS and obstructive coronary artery disease were apparently treated less aggressively with secondary preventive drugs than were men, being less likely to receive aspirin, beta-blockers and statins at discharge. Overall, coronary revascularization appears to be performed in a similar proportion of women and men - once angiography has been performed and the coronary anatomy is known. However, substantial geographic variation exists in the relative rate of coronary angiography in men and women. In United Kingdom coronary revascularization tends to be done less frequently in women. Our study, therefore, demonstrates a gender bias in the delivery of secondary drug treatments for ACS, even for patients with documented significant coronary disease.

  8. Missing Data Bias on a Selective Hedging Strategy

    Directory of Open Access Journals (Sweden)

    Kiss Gábor Dávid

    2017-03-01

    Full Text Available Foreign exchange rates affect corporate profitability both on the macro and cash-flow level. The current study analyses the bias of missing data on a selective hedging strategy, where currency options are applied in case of Value at Risk (1% signs. However, there can be special occasions when one or some data is missing due to lack of a trading activity. This paper focuses on the impact of different missing data handling methods on GARCH and Value at Risk model parameters, because of selective hedging and option pricing based on them. The main added value of the current paper is the comparison of the impact of different methods, such as listwise deletion, mean substitution, and maximum likelihood based Expectation Maximization, on risk management because this subject has insufficient literature. The current study tested daily closing data of floating currencies from Kenya (KES, Ghana (GHS, South Africa (ZAR, Tanzania (TZS, Uganda (UGX, Gambia (GMD, Madagascar (MGA and Mozambique (MZN in USD denomination against EUR/USD rate between March 8, 2000 and March 6, 2015 acquired from the Bloomberg database. Our results suggested the biases of missingness on Value at Risk and volatility models, presenting significant differences among the number of extreme fluctuations or model parameters. A selective hedging strategy can have different expenditures due to the choice of method. This paper suggests the usage of mean substitution or listwise deletion for daily financial time series due to their tendency to have a close to zero first momentum

  9. Thermodynamics of the polaron master equation at finite bias

    International Nuclear Information System (INIS)

    Krause, Thilo; Brandes, Tobias; Schaller, Gernot; Esposito, Massimiliano

    2015-01-01

    We study coherent transport through a double quantum dot. Its two electronic leads induce electronic matter and energy transport and a phonon reservoir contributes further energy exchanges. By treating the system-lead couplings perturbatively, whereas the coupling to vibrations is treated non-perturbatively in a polaron-transformed frame, we derive a thermodynamic consistent low-dimensional master equation. When the number of phonon modes is finite, a Markovian description is only possible when these couple symmetrically to both quantum dots. For a continuum of phonon modes however, also asymmetric couplings can be described with a Markovian master equation. We compute the electronic current and dephasing rate. The electronic current enables transport spectroscopy of the phonon frequency and displays signatures of Franck-Condon blockade. For infinite external bias but finite tunneling bandwidths, we find oscillations in the current as a function of the internal bias due to the electron-phonon coupling. Furthermore, we derive the full fluctuation theorem and show its identity to the entropy production in the system

  10. The evolution of mate choice and mating biases.

    Science.gov (United States)

    Kokko, Hanna; Brooks, Robert; Jennions, Michael D; Morley, Josephine

    2003-03-22

    We review the current status of three well-established models (direct benefits, indirect benefits and sensory drive) and one newcomer (antagonistic chase-away) of the evolution of mate choice and the biases that are expressed during choice. We highlight the differences and commonalities in the underlying genetics and evolutionary dynamics of these models. We then argue that progress in understanding the evolution of mate choice is currently hampered by spurious distinctions among models and a misguided tendency to test the processes underlying each model as mutually exclusive alternatives. Finally, we suggest potentially fruitful directions for future theoretical and empirical research.

  11. Groundwater–Surface Water Exchange

    DEFF Research Database (Denmark)

    Karan, Sachin

    The exchange of groundwater-surface water has been invetigated in the western part of Denmark. Holtum AA provides the framework for all the performed investigations. Several methods are used, primarily eld based measurements ombined with numerical models to achieve insight to the governing...... processes of interaction between groundwater and surface water. By using heat as a tracer it has been possible to use temperature directly as calibrationtargets in a groundwater and heat transport model. Thus, it is possible to use heat investigate the change in groundwater discharge in dynamic conditions...... relatered to rainfall-runo events. By combining geochemical, geophysical and hydrogeological models with numerical modeling, groundwater flow paths to a stream were investigated in a wetland. By combining the dierent tracers, condence in the paramters of the numerical model could be established...

  12. Automation bias in electronic prescribing.

    Science.gov (United States)

    Lyell, David; Magrabi, Farah; Raban, Magdalena Z; Pont, L G; Baysari, Melissa T; Day, Richard O; Coiera, Enrico

    2017-03-16

    Clinical decision support (CDS) in e-prescribing can improve safety by alerting potential errors, but introduces new sources of risk. Automation bias (AB) occurs when users over-rely on CDS, reducing vigilance in information seeking and processing. Evidence of AB has been found in other clinical tasks, but has not yet been tested with e-prescribing. This study tests for the presence of AB in e-prescribing and the impact of task complexity and interruptions on AB. One hundred and twenty students in the final two years of a medical degree prescribed medicines for nine clinical scenarios using a simulated e-prescribing system. Quality of CDS (correct, incorrect and no CDS) and task complexity (low, low + interruption and high) were varied between conditions. Omission errors (failure to detect prescribing errors) and commission errors (acceptance of false positive alerts) were measured. Compared to scenarios with no CDS, correct CDS reduced omission errors by 38.3% (p < .0001, n = 120), 46.6% (p < .0001, n = 70), and 39.2% (p < .0001, n = 120) for low, low + interrupt and high complexity scenarios respectively. Incorrect CDS increased omission errors by 33.3% (p < .0001, n = 120), 24.5% (p < .009, n = 82), and 26.7% (p < .0001, n = 120). Participants made commission errors, 65.8% (p < .0001, n = 120), 53.5% (p < .0001, n = 82), and 51.7% (p < .0001, n = 120). Task complexity and interruptions had no impact on AB. This study found evidence of AB omission and commission errors in e-prescribing. Verification of CDS alerts is key to avoiding AB errors. However, interventions focused on this have had limited success to date. Clinicians should remain vigilant to the risks of CDS failures and verify CDS.

  13. Exchanging Description Logic Knowledge Bases

    NARCIS (Netherlands)

    Arenas, M.; Botoeva, E.; Calvanese, D.; Ryzhikov, V.; Sherkhonov, E.

    2012-01-01

    In this paper, we study the problem of exchanging knowledge between a source and a target knowledge base (KB), connected through mappings. Differently from the traditional database exchange setting, which considers only the exchange of data, we are interested in exchanging implicit knowledge. As

  14. 75 FR 4889 - Self-Regulatory Organizations; New York Stock Exchange LLC; Notice of Filing and Immediate...

    Science.gov (United States)

    2010-01-29

    ... Exchange for NYSE-listed securities that was established by means of a joint venture between the Exchange... interest and unfair competitive advantage. * * * These conditions appear reasonably designed to promote...

  15. Fringe biasing: A variance reduction technique for optically thick meshes

    International Nuclear Information System (INIS)

    Smedley-Stevenson, R. P.

    2013-01-01

    Fringe biasing is a stratified sampling scheme applicable to Monte Carlo thermal radiation transport codes. The thermal emission source in optically thick cells is partitioned into separate contributions from the cell interiors (where the likelihood of the particles escaping the cells is virtually zero) and the 'fringe' regions close to the cell boundaries. Thermal emission in the cell interiors can now be modelled with fewer particles, the remaining particles being concentrated in the fringes so that they are more likely to contribute to the energy exchange between cells. Unlike other techniques for improving the efficiency in optically thick regions (such as random walk and discrete diffusion treatments), fringe biasing has the benefit of simplicity, as the associated changes are restricted to the sourcing routines with the particle tracking routines being unaffected. This paper presents an analysis of the potential for variance reduction achieved from employing the fringe biasing technique. The aim of this analysis is to guide the implementation of this technique in Monte Carlo thermal radiation codes, specifically in order to aid the choice of the fringe width and the proportion of particles allocated to the fringe (which are interrelated) in multi-dimensional simulations, and to confirm that the significant levels of variance reduction achieved in simulations can be understood by studying the behaviour for simple test cases. The variance reduction properties are studied for a single cell in a slab geometry purely absorbing medium, investigating the accuracy of the scalar flux and current tallies on one of the interfaces with the surrounding medium. (authors)

  16. Heat exchanger restart evaluation

    International Nuclear Information System (INIS)

    Morrison, J.M.; Hirst, C.W.; Lentz, T.F.

    1992-01-01

    On December 24, 1991, the K-Reactor was in the shutdown mode with full AC process water flow and full cooling water flow. Safety rod testing was being performed as part of the power ascension testing program. The results of cooling water samples indicated tritium concentrations higher than allowable. Further sampling and testing confirmed a Process Water System to Cooling Water System leak in heat exchanger 4A (HX 4A). The heat exchanger was isolated and the plant shutdown. Heat exchanger 4A was removed from the plant and moved to C-Area prior to performing examinations and diagnostic testing. This included locating and identifying the leaking tube or tubes, eddy current examination of the leaking tube and a number of adjacent tubes, visually inspecting the leaking tube from both the inside as well as the area surrounding the identified tube. The leaking tube was removed and examined metallurgically to determine the failure mechanism. In addition ten other tubes that either exhibited eddy current indications or would represent a baseline condition were removed from heat exchanger 4A for metallurgical examination. Additional analysis and review of heat exchanger leakage history was performed to determine if there are any patterns which can be used for predictive purposes. Compensatory actions have been taken to improve the sensitivity and response time to any future events of this type. The results of these actions are summarized

  17. Heat exchanger restart evaluation

    International Nuclear Information System (INIS)

    Morrison, J.M.; Hirst, C.W.; Lentz, T.F.

    1992-01-01

    On December 24, 1991, the K-Reactor was in the shutdown mode with full AC process water flow and full cooling water flow. Safety rod testing was being performed as part of the power ascension testing program. The results of cooling water samples indicated tritium concentrations higher than allowable. Further sampling and testing confirmed a Process Water System to Cooling Water System leak in heat exchanger 4A (HX 4A). The heat exchanger was isolated and the plant shutdown. Heat exchanger 4A was removed from the plant and moved to C-Area prior to performing examinations and diagnostic testing. This included locating and identifying the leaking tube or tubes, eddy current examination of the leaking tube and a number of adjacent tubes, visually inspecting the leaking tube from both the inside as well as the area surrounding the identified tube. The leaking tube was removed and examined metallurgically to determine the failure mechanism. In addition ten other tubes that either exhibited eddy current indications or would represent a baseline condition were removed from heat exchanger 4A for metallurgical examination. Additional analysis and review of heat exchanger leakage history was performed to determine if there are any patterns which can be used for predictive purposes. Compensatory actions have been taken to improve the sensitivity and response time to any future events of this type. The results of these actions are summary herein

  18. Heat exchanger restart evaluation

    International Nuclear Information System (INIS)

    Morrison, J.M.; Hirst, C.W.; Lentz, T.F.

    1992-01-01

    On December 24, 1991, the K-Reactor was in the shutdown mode with full AC process water flow and full cooling water flow. Safety rod testing was being performed as part of the power ascension testing program. The results of cooling water samples indicated tritium concentrations higher than allowable. Further sampling and testing confirmed a Process Water System to Cooling Water System leak in heat exchanger 4A (HX 4A). The heat exchanger was isolated and the plant shutdown. Heat exchanger 4kA was removed from the plant and moved to C-Area prior to performing examinations and diagnostic testing. This included locating and identifying the leaking tube or tubes, eddy current examination of the leaking tube and a number of adjacent tubes, visually inspecting the leaking tube from both the inside as well as the area surrounding the failure mechanism. In addition ten other tubes that either exhibited eddy current indications or would represent a baseline condition were removed from heat exchanger 4A for metallurgical examination. Additional analysis and review of heat exchanger leakage history was performed to determine if there are any patterns which can be used for predictive purposes. Compensatory actions have been taken to improve the sensitivity and response time to any future events of this type. The results of these actions are summarized herein

  19. The role of cognitive biases in short-term psychodynamic psychotherapy.

    Science.gov (United States)

    Kramer, Ueli; Ortega, Diana; Ambresin, Gilles; Despland, Jean-Nicolas; de Roten, Yves

    2017-09-13

    The concept of biased thinking - or cognitive biases - is relevant to psychotherapy research and clinical conceptualization, beyond cognitive theories. The present naturalistic study aimed to examine the changes in biased thinking over the course of a short-term dynamic psychotherapy (STDP) and to discover potential links between these changes and symptomatic improvement. This study focuses on 32 self-referred patients consulting for Adjustment Disorder according to DSM-IV-TR. The therapists were experienced psychodynamically oriented psychiatrists and psychotherapists. Coding of cognitive biases (using the Cognitive Errors Rating Scale; CERS) was made by external raters based on transcripts of interviews of psychotherapy; the reliability of these ratings on a randomly chosen 24% of all sessions was established. Based on the Symptom Check List SCL-90-R given before and after, the Reliable Change Index (RCI) was used. The assessment of cognitive errors was done at three time points: early (session 4-7), mid-treatment (session 12-17), and close to the end (after session 20) of the treatment. The results showed that the total frequency of cognitive biases was stable over time (p = .20), which was true both for positive and for negative cognitive biases. In exploring the three main subscales of the CERS, we found a decrease in selective abstraction (p = .02) and an increase in personalization (p = .05). A significant link between RCI scores (outcome) and frequency of positive cognitive biases was found, suggesting that biases towards the positive might have a protective function in psychotherapy. Therapists may be attentive to changes in biased thinking across short-term dynamic psychotherapy for adjustment disorder. Therapists may foster the emergence of positive cognitive biases at mid-treatment for adjustment disorder. © 2017 The British Psychological Society.

  20. A review of bias flow liners for acoustic damping in gas turbine combustors

    Science.gov (United States)

    Lahiri, C.; Bake, F.

    2017-07-01

    The optimized design of bias flow liner is a key element for the development of low emission combustion systems in modern gas turbines and aero-engines. The research of bias flow liners has a fairly long history concerning both the parameter dependencies as well as the methods to model the acoustic behaviour of bias flow liners under the variety of different bias and grazing flow conditions. In order to establish an overview over the state of the art, this paper provides a comprehensive review about the published research on bias flow liners and modelling approaches with an extensive study of the most relevant parameters determining the acoustic behaviour of these liners. The paper starts with a historical description of available investigations aiming on the characterization of the bias flow absorption principle. This chronological compendium is extended by the recent and ongoing developments in this field. In a next step the fundamental acoustic property of bias flow liner in terms of the wall impedance is introduced and the different derivations and formulations of this impedance yielding the different published model descriptions are explained and compared. Finally, a parametric study reveals the most relevant parameters for the acoustic damping behaviour of bias flow liners and how this is reflected by the various model representations. Although the general trend of the investigated acoustic behaviour is captured by the different models fairly well for a certain range of parameters, in the transition region between the resonance dominated and the purely bias flow related regime all models lack the correct damping prediction. This seems to be connected to the proper implementation of the reactance as a function of bias flow Mach number.

  1. Testing Long-Run Purchasing Power Parity under Exchange Rate Targeting

    OpenAIRE

    Sophocles N. Brissimis; Dimitris A. Sideris; Fragiska K. Voumvaki

    2004-01-01

    The present paper exploits the idea that empirical estimates of the long-run PPP relationship may compound two distinct influences coming from the behavior of market participants and policy makers when the latter are targeting the exchange rate. This tends to bias tests of long-run PPP against its acceptance. The validity of the theoretical arguments is assessed by drawing on the experience of two European Union countries, Greece and France for the post-Bretton Woods period. Estimation biases...

  2. Apparent exchange rate for breast cancer characterization.

    Science.gov (United States)

    Lasič, Samo; Oredsson, Stina; Partridge, Savannah C; Saal, Lao H; Topgaard, Daniel; Nilsson, Markus; Bryskhe, Karin

    2016-05-01

    Although diffusion MRI has shown promise for the characterization of breast cancer, it has low specificity to malignant subtypes. Higher specificity might be achieved if the effects of cell morphology and molecular exchange across cell membranes could be disentangled. The quantification of exchange might thus allow the differentiation of different types of breast cancer cells. Based on differences in diffusion rates between the intra- and extracellular compartments, filter exchange spectroscopy/imaging (FEXSY/FEXI) provides non-invasive quantification of the apparent exchange rate (AXR) of water between the two compartments. To test the feasibility of FEXSY for the differentiation of different breast cancer cells, we performed experiments on several breast epithelial cell lines in vitro. Furthermore, we performed the first in vivo FEXI measurement of water exchange in human breast. In cell suspensions, pulsed gradient spin-echo experiments with large b values and variable pulse duration allow the characterization of the intracellular compartment, whereas FEXSY provides a quantification of AXR. These experiments are very sensitive to the physiological state of cells and can be used to establish reliable protocols for the culture and harvesting of cells. Our results suggest that different breast cancer subtypes can be distinguished on the basis of their AXR values in cell suspensions. Time-resolved measurements allow the monitoring of the physiological state of cells in suspensions over the time-scale of hours, and reveal an abrupt disintegration of the intracellular compartment. In vivo, exchange can be detected in a tumor, whereas, in normal tissue, the exchange rate is outside the range experimentally accessible for FEXI. At present, low signal-to-noise ratio and limited scan time allows the quantification of AXR only in a region of interest of relatively large tumors. © 2016 The Authors. NMR in Biomedicine published by John Wiley & Sons Ltd.

  3. Removing Malmquist bias from linear regressions

    Science.gov (United States)

    Verter, Frances

    1993-01-01

    Malmquist bias is present in all astronomical surveys where sources are observed above an apparent brightness threshold. Those sources which can be detected at progressively larger distances are progressively more limited to the intrinsically luminous portion of the true distribution. This bias does not distort any of the measurements, but distorts the sample composition. We have developed the first treatment to correct for Malmquist bias in linear regressions of astronomical data. A demonstration of the corrected linear regression that is computed in four steps is presented.

  4. delta-biased Josephson tunnel junctions

    DEFF Research Database (Denmark)

    Monaco, R.; Mygind, Jesper; Koshelet, V.

    2010-01-01

    Abstract: The behavior of a long Josephson tunnel junction drastically depends on the distribution of the dc bias current. We investigate the case in which the bias current is fed in the central point of a one-dimensional junction. Such junction configuration has been recently used to detect...... the persistent currents circulating in a superconducting loop. Analytical and numerical results indicate that the presence of fractional vortices leads to remarkable differences from the conventional case of uniformly distributed dc bias current. The theoretical findings are supported by detailed measurements...

  5. Microgravity condensing heat exchanger

    Science.gov (United States)

    Thomas, Christopher M. (Inventor); Ma, Yonghui (Inventor); North, Andrew (Inventor); Weislogel, Mark M. (Inventor)

    2011-01-01

    A heat exchanger having a plurality of heat exchanging aluminum fins with hydrophilic condensing surfaces which are stacked and clamped between two cold plates. The cold plates are aligned radially along a plane extending through the axis of a cylindrical duct and hold the stacked and clamped portions of the heat exchanging fins along the axis of the cylindrical duct. The fins extend outwardly from the clamped portions along approximately radial planes. The spacing between fins is symmetric about the cold plates, and are somewhat more closely spaced as the angle they make with the cold plates approaches 90.degree.. Passageways extend through the fins between vertex spaces which provide capillary storage and communicate with passageways formed in the stacked and clamped portions of the fins, which communicate with water drains connected to a pump externally to the duct. Water with no entrained air is drawn from the capillary spaces.

  6. Multicomponent ion exchange model

    International Nuclear Information System (INIS)

    Robinson, S.M.; Arnold, W.D.; Byers, C.H.

    1990-01-01

    The optimization of ion-exchange column design becomes increasingly important in applications where high efficiency is required to remove trace components in wastewater to very low discharge requirements and for treating hazardous wastewaters where the disposal costs for secondary waste is extremely high. A predictive mathematical model is being developed for improved design of ion-exchange columns for treatment of wastewaters which are contaminated with trace quantities of Sr-90 and Cs-137. Equilibria isotherms and mass transfer mechanisms are being experimentally determined for isothermal multicomponent ion exchange of Ca, Mg, Na, Ca, and Sr with Ionsive IE-95 chabazite zeolite. These equations are being included in a mathematical model to determine the cation breakthrough curves for different column configurations and operating conditions

  7. Sorption by cation exchange

    International Nuclear Information System (INIS)

    Bradbury, M.H.; Baeyens, B.

    1994-04-01

    A procedure for introducing exchange into geochemical/surface complexation codes is described. Beginning with selectivity coefficients, K c , defined in terms of equivalent fractional ion occupancies, a general expression for the molar based exchange code input parameters, K ex , is derived. In natural systems the uptake of nuclides onto complex sorbents often occurs by more than one mechanism. The incorporation of cation exchange and surface complexation into a geochemical code therefore enables sorption by both mechanisms to be calculated simultaneously. The code and model concepts are tested against sets of experimental data from widely different sorption studies. A proposal is made to set up a data base of selectivity coefficients. Such a data base would form part of a more general one consisting of sorption mechanism specific parameters to be used in conjunction with geochemical/sorption codes to model and predict sorption. (author) 6 figs., 6 tabs., 26 refs

  8. Modular heat exchanger

    Science.gov (United States)

    Culver, Donald W.

    1978-01-01

    A heat exchanger for use in nuclear reactors includes a heat exchange tube bundle formed from similar modules each having a hexagonal shroud containing a large number of thermally conductive tubes which are connected with inlet and outlet headers at opposite ends of each module, the respective headers being adapted for interconnection with suitable inlet and outlet manifold means. In order to adapt the heat exchanger for operation in a high temperature and high pressure environment and to provide access to all tube ports at opposite ends of the tube bundle, a spherical tube sheet is arranged in sealed relation across the chamber with an elongated duct extending outwardly therefrom to provide manifold means for interconnection with the opposite end of the tube bundle.

  9. Ion exchange phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Bourg, I.C.; Sposito, G.

    2011-05-01

    Ion exchange phenomena involve the population of readily exchangeable ions, the subset of adsorbed solutes that balance the intrinsic surface charge and can be readily replaced by major background electrolyte ions (Sposito, 2008). These phenomena have occupied a central place in soil chemistry research since Way (1850) first showed that potassium uptake by soils resulted in the release of an equal quantity of moles of charge of calcium and magnesium. Ion exchange phenomena are now routinely modeled in studies of soil formation (White et al., 2005), soil reclamation (Kopittke et al., 2006), soil fertilitization (Agbenin and Yakubu, 2006), colloidal dispersion/flocculation (Charlet and Tournassat, 2005), the mechanics of argillaceous media (Gajo and Loret, 2007), aquitard pore water chemistry (Tournassat et al., 2008), and groundwater (Timms and Hendry, 2007; McNab et al., 2009) and contaminant hydrology (Chatterjee et al., 2008; van Oploo et al., 2008; Serrano et al., 2009).

  10. Selection bias at the heterosexual HIV-1 transmission bottleneck

    Science.gov (United States)

    Carlson, Jonathan M.; Schaefer, Malinda; Monaco, Daniela C.; Batorsky, Rebecca; Claiborne, Daniel T.; Prince, Jessica; Deymier, Martin J.; Ende, Zachary S.; Klatt, Nichole R.; DeZiel, Charles E.; Lin, Tien-Ho; Peng, Jian; Seese, Aaron M.; Shapiro, Roger; Frater, John; Ndung’u, Thumbi; Tang, Jianming; Goepfert, Paul; Gilmour, Jill; Price, Matt A.; Kilembe, William; Heckerman, David; Goulder, Philip J.R.; Allen, Todd M.; Allen, Susan; Hunter, Eric

    2014-01-01

    factors, suggests that transmission is frequently characterized by many abortive transmission events in which some target cells are nonproductively infected. Moreover, for efficient transmission, some changes that favored survival in the transmitting partner are frequently discarded, resulting in overall slower evolution of HIV-1 in the population. Paradoxically, by increasing the selection bias at the transmission bottleneck, reduction of susceptibility may increase the expected fitness of breakthrough viruses that establish infection and may therefore worsen the prognosis for the newly infected partner. Conversely, preventative or therapeutic approaches that weaken the virus may reduce overall transmission rates via a mechanism that is independent from the quantity of circulating virus, and may therefore provide long-term benefits even upon breakthrough infection. PMID:25013080

  11. Heat exchanger panel

    Science.gov (United States)

    Warburton, Robert E. (Inventor); Cuva, William J. (Inventor)

    2005-01-01

    The present invention relates to a heat exchanger panel which has broad utility in high temperature environments. The heat exchanger panel has a first panel, a second panel, and at least one fluid containment device positioned intermediate the first and second panels. At least one of the first panel and the second panel have at least one feature on an interior surface to accommodate the at least one fluid containment device. In a preferred embodiment, each of the first and second panels is formed from a high conductivity, high temperature composite material. Also, in a preferred embodiment, the first and second panels are joined together by one or more composite fasteners.

  12. Classification of exchange currents

    International Nuclear Information System (INIS)

    Friar, J.L.

    1983-01-01

    After expansion of the vector and axial vector currents in powers of (v/c), a heretofore unremarked regularity results. Meson exchange currents can be classified into types I and II, according to the way they satisfy the constraints of special relativity. The archetypes of these two categories are the impulse approximation to the vector and axial vector currents. After a brief discussion of these constraints, the (rhoπγ) and (ωsigmaγ) exchange currents are constructed and classified, and used to illustrate a number of important points which are often overlooked

  13. Small Column Ion Exchange

    International Nuclear Information System (INIS)

    Huff, Thomas

    2010-01-01

    Small Column Ion Exchange (SCIX) leverages a suite of technologies developed by DOE across the complex to achieve lifecycle savings. Technologies are applicable to multiple sites. Early testing supported multiple sites. Balance of SRS SCIX testing supports SRS deployment. A forma Systems Engineering Evaluation (SEE) was performed and selected Small Column Ion Exchange columns containing Crystalline Silicotitanate (CST) in a 2-column lead/lag configuration. SEE considered use of Spherical Resorcinol-Formaldehyde (sRF). Advantages of approach at SRS include: (1) no new buildings, (2) low volume of Cs waste in solid form compared to aqueous strip effluent; and availability of downstream processing facilities for immediate processing of spent resin.

  14. Chemosensory communication of gender information: Masculinity bias in body odor perception and femininity bias introduced by chemosignals during social perception

    Directory of Open Access Journals (Sweden)

    Smiljana eMutic

    2016-01-01

    Full Text Available Human body odor is a source of important social information. In this study, we explore whether the sex of an individual can be established based on smelling axillary odor and whether exposure to male and female odors biases chemosensory and social perception. In a double-blind, pseudo-randomized application, 31 healthy normosmic heterosexual male and female raters were exposed to male and female chemosignals (odor samples of 27 heterosexual donors collected during a cardio workout and a no odor sample. Recipients rated chemosensory samples on a masculinity-femininity scale and provided intensity, familiarity and pleasantness ratings. Additionally, the modulation of social perception (gender-neutral faces and personality attributes and affective introspection (mood by male and female chemosignals was assessed. Male and female axillary odors were rated as rather masculine, regardless of the sex of the donor. As opposed to the masculinity bias in the odor perception, a femininity bias modulating social perception appeared. A facilitated femininity detection in gender-neutral faces and personality attributes in association with both male and female chemosignals appeared. No chemosensory effect on mood of the rater was observed. The results are discussed with regards to the use of male and female chemosignals in affective and social communication.

  15. Accounting for Unobservable Exposure Time Bias Wh...

    Data.gov (United States)

    U.S. Department of Health & Human Services — Accounting for Unobservable Exposure Time Bias When Using Medicare Prescription Drug Data Unobservable exposure time is common among Medicare Part D beneficiaries,...

  16. Biases in Gender-Role Research

    Science.gov (United States)

    Romero, Det P.

    1977-01-01

    Despite the profession's code of ethics that opposes discrimination because of sex, the knowledge base on which social work is built is permeated by bias. In this review of the literature, the author identifies trends that illustrate this dilemma. (Author)

  17. Students' gender bias in teaching evaluations

    Directory of Open Access Journals (Sweden)

    Narissra Punyanunt-Carter

    2015-09-01

    Full Text Available The goal of this study was to investigate if there is gender bias in student evaluations. Researchers administered a modified version of the teacher evaluation forms to 58 students (male=30; female=28 in a basic introductory communications class. Half the class was instructed to fill out the survey about a male professor, and the other half a female professor. Researchers broke down the evaluation results question by question in order to give a detailed account of the findings. Results revealed that there is certainly some gender bias at work when students evaluate their instructors. It was also found that gender bias does not significantly affect the evaluations. The results align with other findings in the available literature, which point to some sort of pattern regarding gender bias in evaluations, but it still seems to be inconsequential.  DOI: 10.18870/hlrc.v5i3.234

  18. Bayesian long branch attraction bias and corrections.

    Science.gov (United States)

    Susko, Edward

    2015-03-01

    Previous work on the star-tree paradox has shown that Bayesian methods suffer from a long branch attraction bias. That work is extended to settings involving more taxa and partially resolved trees. The long branch attraction bias is confirmed to arise more broadly and an additional source of bias is found. A by-product of the analysis is methods that correct for biases toward particular topologies. The corrections can be easily calculated using existing Bayesian software. Posterior support for a set of two or more trees can thus be supplemented with corrected versions to cross-check or replace results. Simulations show the corrections to be highly effective. © The Author(s) 2014. Published by Oxford University Press, on behalf of the Society of Systematic Biologists. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  19. Minimum Bias Interaction Triggers in ATLAS

    CERN Document Server

    Kwee, R E; The ATLAS collaboration

    2010-01-01

    Since the restart of the LHC in November 2009, ATLAS has collected inelastic ppcollisions to perform first measurements on charged particle densities. These measurements will help to constrain various models describing phenomenologically soft parton interactions. Understanding the trigger efficiencies for different event types are therefore crucial to minimize any possible bias in the event selection. ATLAS uses two main minimum bias triggers, featuring complementary detector components and trigger levels. While a hardware based first trigger level situated in the forward regions with 2.2 < |eta| < 3.8 has been proven to select pp-collisions very efficiently, the Inner Detector based minimum bias trigger uses a random seed on filled bunches and central tracking detectors for the event selection. Both triggers were essential for the analysis of kinematic spectra of charged particles. Their performance and trigger efficiency measurements as well as studies on possible bias sources will be presente...

  20. Autobiographical memory bias in social anxiety.

    Science.gov (United States)

    Krans, Julie; de Bree, June; Bryant, Richard A

    2014-01-01

    In social anxiety the psychological self is closely related to the feared stimulus. Socially anxious individuals are, by definition, concerned about how the self is perceived and evaluated by others. As autobiographical memory is strongly related to views of the self it follows that biases in autobiographical memory play an important role in social anxiety. In the present study high (n = 19) and low (n = 29) socially anxious individuals were compared on autobiographical memory bias, current goals, and self-discrepancy. Individuals high in social anxiety showed a bias towards recalling more negative and more social anxiety-related autobiographical memories, reported more current goals related to overcoming social anxiety, and showed larger self-discrepancies. The pattern of results is largely in line with earlier research in individuals with PTSD and complicated grief. This suggests that the relation between autobiographical memory bias and the self is a potentially valuable trans-diagnostic factor.

  1. A Bias in the Diagnosis of Schizophrenia

    Science.gov (United States)

    Reade, William Kent; Wertheimer, Michael

    1976-01-01

    Research shows a relationship between diagnoses of schizophrenia among twins. It was studied whether information that a twin was schizophrenic would bias diagnoses. Such information almost doubled the rater's estimates of probability of schizophrenia in a hypothetical case history. (NG)

  2. Wind models for the NSTS ascent trajectory biasing for wind load alleviation

    Science.gov (United States)

    Smith, O. E.; Adelfang, S. I.; Batts, G. W.

    1990-01-01

    New concepts are presented for aerospace vehicle ascent wind profile biasing. The purpose for wind biasing the ascent trajectory is to provide ascent wind loads relief and thus decrease the probability for launch delays due to wind loads exceeding critical limits. Wind biasing trajectories to the the profile of monthly mean winds have been widely used for this purpose. The wind profile models presented give additional alternatives for wind biased trajectories. They are derived from the properties of the bivariate normal probability function using the available wind statistical parameters for the launch site. The analytical expressions are presented to permit generalizations. Specific examples are given to illustrate the procedures. The wind profile models can be used to establish the ascent trajectory steering commands to guide the vehicle through the first stage. For the National Space Transportation System (NSTS) program these steering commands are called I-loads.

  3. Publication bias in studies of an applied behavior-analytic intervention: an initial analysis.

    Science.gov (United States)

    Sham, Elyssa; Smith, Tristram

    2014-01-01

    Publication bias arises when studies with favorable results are more likely to be reported than are studies with null findings. If this bias occurs in studies with single-subject experimental designs(SSEDs) on applied behavior-analytic (ABA) interventions, it could lead to exaggerated estimates of intervention effects. Therefore, we conducted an initial test of bias by comparing effect sizes, measured by percentage of nonoverlapping data (PND), in published SSED studies (n=21) and unpublished dissertations (n=10) on 1 well-established intervention for children with autism, pivotal response treatment (PRT). Although published and unpublished studies had similar methodologies, the mean PND in published studies was 22% higher than in unpublished studies, 95% confidence interval (4%, 38%). Even when unpublished studies are included, PRT appeared to be effective (PNDM=62%). Nevertheless, the disparity between published and unpublished studies suggests a need for further assessment of publication bias in the ABA literature.

  4. Don't panic: interpretation bias is predictive of new onsets of panic disorder.

    Science.gov (United States)

    Woud, Marcella L; Zhang, Xiao Chi; Becker, Eni S; McNally, Richard J; Margraf, Jürgen

    2014-01-01

    Psychological models of panic disorder postulate that interpretation of ambiguous material as threatening is an important maintaining factor for the disorder. However, demonstrations of whether such a bias predicts onset of panic disorder are missing. In the present study, we used data from the Dresden Prediction Study, in which a epidemiologic sample of young German women was tested at two time points approximately 17 months apart, allowing the study of biased interpretation as a potential risk factor. At time point one, participants completed an Interpretation Questionnaire including two types of ambiguous scenarios: panic-related and general threat-related. Analyses revealed that a panic-related interpretation bias predicted onset of panic disorder, even after controlling for two established risk factors: anxiety sensitivity and fear of bodily sensations. This is the first prospective study demonstrating the incremental validity of interpretation bias as a predictor of panic disorder onset. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. Drug Establishments Current Registration Site

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Drug Establishments Current Registration Site (DECRS) is a database of current information submitted by drug firms to register establishments (facilities) which...

  6. GENDER DIFFERENCES AND BIASES IN THE WORKPLACE

    OpenAIRE

    Shruti Srivastava*1 & Dr. Shweta S. Kulshrestha2

    2018-01-01

    Gender equality in the workplace has been a major concern for almost all the organizations and countries. Even in most developed countries we cannot find complete gender equality in true sense. This paper aims to discuss whether there is gender biasness in organizations or not? Gender biasness is considered as a major constraint towards the development process in any of the country and thus we have made an attempt to determine the root causes for gender gap that persists in our society. A...

  7. Media bias, news customization and competition

    OpenAIRE

    Pires, Armando José Garcia

    2010-01-01

    The media bias literature has focused its attention on single-ideology media firms. We analyze the incentives for media firms to adopt a multi-ideology strategy. A multi-ideology strategy occurs when a media firm adapts news to consumers’ political preferences. In this sense, news customization can reduce media bias, since media firms can cover a larger variety of political opinions. We show that although the incentives to customize are larger under duopoly than under monopoly, a monopolist m...

  8. Biased liquid crystal photonic bandgap fiber

    DEFF Research Database (Denmark)

    Weirich, Johannes; Lægsgaard, Jesper; Alkeskjold, Thomas Tanggaard

    2008-01-01

    We simulate the director structure of all capillaries in a biased photonic crystal fiber infiltrated with liquid crystals. Various mode simulations for different capillaries show the necessity to consider the entire structure.......We simulate the director structure of all capillaries in a biased photonic crystal fiber infiltrated with liquid crystals. Various mode simulations for different capillaries show the necessity to consider the entire structure....

  9. Controlling Selection Bias in Causal Inference

    Science.gov (United States)

    2012-02-01

    and cervix . Journal of the National Cancer Institute 11 1269–1275. Didelez, V., Kreiner, S. and Keiding, N. (2010). Graphical models for inference...Endometrial Cancer (Y ) was overestimated in the data studied. One of the symptoms of the use of Oe- strogen is vaginal bleeding (W ) (Fig. 1(c)), and the...whether similar bounds can be de - rived in the presence of selection bias. We will show that selection bias can be removed entirely through the use of

  10. Asymmetric Exchange Rate Exposures: A Search for the Effect of Real Options

    DEFF Research Database (Denmark)

    Aabo, Tom

    2001-01-01

    Real options like the ability to reallocate production resources can lead to an asymmetric exchange rate exposure. Using a stock market approach in which the exchange rate exposure is derived from the information content in the stock prices this study examines the extra-market exchange rate...... exposures of a group of blue chip, industrial companies listed on the Copenhagen Stock Exchange. In these companies the existence of real options is an integrated part of the exchange rate exposure management process. The result of the stock market approach is mixed. Statistically significant asymmetric...... exchange rate exposures are identified successfully but the asymmetries can only to a limited extent be explained by the existence of real options. Financial options and pricing to market are competing explanations. Omitted variable bias further blurs the picture. These problems and the concept of path...

  11. Systematic biases in human heading estimation.

    Directory of Open Access Journals (Sweden)

    Luigi F Cuturi

    Full Text Available Heading estimation is vital to everyday navigation and locomotion. Despite extensive behavioral and physiological research on both visual and vestibular heading estimation over more than two decades, the accuracy of heading estimation has not yet been systematically evaluated. Therefore human visual and vestibular heading estimation was assessed in the horizontal plane using a motion platform and stereo visual display. Heading angle was overestimated during forward movements and underestimated during backward movements in response to both visual and vestibular stimuli, indicating an overall multimodal bias toward lateral directions. Lateral biases are consistent with the overrepresentation of lateral preferred directions observed in neural populations that carry visual and vestibular heading information, including MSTd and otolith afferent populations. Due to this overrepresentation, population vector decoding yields patterns of bias remarkably similar to those observed behaviorally. Lateral biases are inconsistent with standard bayesian accounts which predict that estimates should be biased toward the most common straight forward heading direction. Nevertheless, lateral biases may be functionally relevant. They effectively constitute a perceptual scale expansion around straight ahead which could allow for more precise estimation and provide a high gain feedback signal to facilitate maintenance of straight-forward heading during everyday navigation and locomotion.

  12. Nature's Heat Exchangers.

    Science.gov (United States)

    Barnes, George

    1991-01-01

    Discusses the heat-transfer systems of different animals. Systems include heat conduction into the ground, heat transferred by convection, heat exchange in lizards, fish and polar animals, the carotid rete system, electromagnetic radiation from animals and people, and plant and animal fiber optics. (MDH)

  13. Chapter 11. Heat Exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Rafferty, Kevin D.; Culver, Gene

    1998-01-01

    Most geothermal fluids, because of their elevated temperature, contain a variety of dissolved chemicals. These chemicals are frequently corrosive toward standard materials of construction. As a result, it is advisable in most cases to isolate the geothermal fluid from the process to which heat is being transferred. The task of heat transfer from the geothermal fluid to a closed process loop is most often handled by a plate heat exchanger. The two most common types used in geothermal applications are: bolted and brazed. For smaller systems, in geothermal resource areas of a specific character, downhole heat exchangers (DHEs) provide a unique means of heat extraction. These devices eliminate the requirement for physical removal of fluid from the well. For this reason, DHE-based systems avoid entirely the environmental and practical problems associated with fluid disposal. Shell and tube heat exchangers play only a minor role in low-temperature, direct-use systems. These units have been in common use in industrial applications for many years and, as a result, are well understood. For these reasons, shell and tube heat exchangers will not be covered in this chapter.

  14. Higher Education Exchange, 2014

    Science.gov (United States)

    Brown, David W., Ed.; Witte, Deborah, Ed.

    2014-01-01

    Research shows that not only does higher education not see the public; when the public, in turn, looks at higher education, it sees mostly malaise, inefficiencies, expense, and unfulfilled promises. Yet, the contributors to this issue of the "Higher Education Exchange" tell of bright spots in higher education where experiments in working…

  15. Upright heat exchanger

    International Nuclear Information System (INIS)

    Martoch, J.; Kugler, V.; Krizek, V.; Strmiska, F.

    1988-01-01

    The claimed heat exchanger is characteristic by the condensate level being maintained directly in the exchanger while preserving the so-called ''dry'' tube plate. This makes it unnecessary to build another pressure vessel into the circuit. The design of the heat exchanger allows access to both tube plates, which facilitates any repair. Another advantage is the possibility of accelerating the indication of leakage from the space of the second operating medium which is given by opening the drainage pipes of the lower bundle into the collar space and from there through to the indication pipe. The exchanger is especially suitable for deployment in the circuits of nuclear power plants where the second operating medium will be hot water of considerably lower purity than is that of the condensate. A rapid display of leakage can prevent any long-term penetration of this water into the condensate, which would result in worsening water quality in the entire secondary circuit of the nuclear power plant. (J.B.). 1 fig

  16. Fuel exchanger control device

    International Nuclear Information System (INIS)

    Kurabayashi, Masaharu.

    1985-01-01

    Purpose: To improve the stability and the operationability of the fuel exchanging work by checking the validity of the data before the initiation of the work. Constitution: A floppy disc stores the initial charging state data showing the arrangement of fuel assemblies in the reactor core pool, data showing the working procedures for the fuel exchange and a final charged state data upon completion of the work. The initial data and the procedure data are read from the disk and stored once into a memory. Then, the initial data are sequentially performed on the memory in accordance with the procedure data and, thereafter, they were compared with the final data read from the disk. After confirming that there are no errors in the working data, the procedure data are orderly instructed to the fuel exchanger for performing fuel replacement. Accordingly, since the data are checked before the initiation of the work, the fuel exchange can be performed automatically thereby improving the operationability thereof. (Yoshino, Y.)

  17. Basic Exchange Rate Theories

    NARCIS (Netherlands)

    J.G.M. van Marrewijk (Charles)

    2005-01-01

    textabstractThis four-chapter overview of basic exchange rate theories discusses (i) the elasticity and absorption approach, (ii) the (long-run) implications of the monetary approach, (iii) the short-run effects of monetary and fiscal policy under various economic conditions, and (iv) the transition

  18. Telephone Exchange Maintenance

    CERN Multimedia

    2005-01-01

    Urgent maintenance work on CERN telephone exchanges will be performed on 24 March from 6 a.m. to 8 a.m. Telephone services may be disrupted or even interrupted during this time. For more details, please contact us by email at Standard.Telephone@cern.ch.

  19. Bias in phylogenetic reconstruction of vertebrate rhodopsin sequences.

    Science.gov (United States)

    Chang, B S; Campbell, D L

    2000-08-01

    Two spurious nodes were found in phylogenetic analyses of vertebrate rhodopsin sequences in comparison with well-established vertebrate relationships. These spurious reconstructions were well supported in bootstrap analyses and occurred independently of the method of phylogenetic analysis used (parsimony, distance, or likelihood). Use of this data set of vertebrate rhodopsin sequences allowed us to exploit established vertebrate relationships, as well as the considerable amount known about the molecular evolution of this gene, in order to identify important factors contributing to the spurious reconstructions. Simulation studies using parametric bootstrapping indicate that it is unlikely that the spurious nodes in the parsimony analyses are due to long branches or other topological effects. Rather, they appear to be due to base compositional bias at third positions, codon bias, and convergent evolution at nucleotide positions encoding the hydrophobic residues isoleucine, leucine, and valine. LogDet distance methods, as well as maximum-likelihood methods which allow for nonstationary changes in base composition, reduce but do not entirely eliminate support for the spurious resolutions. Inclusion of five additional rhodopsin sequences in the phylogenetic analyses largely corrected one of the spurious reconstructions while leaving the other unaffected. The additional sequences not only were more proximal to the corrected node, but were also found to have intermediate levels of base composition and codon bias as compared with neighboring sequences on the tree. This study shows that the spurious reconstructions can be corrected either by excluding third positions, as well as those encoding the amino acids Ile, Val, and Leu (which may not be ideal, as these sites can contain useful phylogenetic signal for other parts of the tree), or by the addition of sequences that reduce problems associated with convergent evolution.

  20. Resistance and resistance fluctuations in random resistor networks under biased percolation.

    Science.gov (United States)

    Pennetta, Cecilia; Reggiani, L; Trefán, Gy; Alfinito, E

    2002-06-01

    We consider a two-dimensional random resistor network (RRN) in the presence of two competing biased processes consisting of the breaking and recovering of elementary resistors. These two processes are driven by the joint effects of an electrical bias and of the heat exchange with a thermal bath. The electrical bias is set up by applying a constant voltage or, alternatively, a constant current. Monte Carlo simulations are performed to analyze the network evolution in the full range of bias values. Depending on the bias strength, electrical failure or steady state are achieved. Here we investigate the steady state of the RRN focusing on the properties of the non-Ohmic regime. In constant-voltage conditions, a scaling relation is found between /(0) and V/V(0), where is the average network resistance, (0) the linear regime resistance, and V0 the threshold value for the onset of nonlinearity. A similar relation is found in constant-current conditions. The relative variance of resistance fluctuations also exhibits a strong nonlinearity whose properties are investigated. The power spectral density of resistance fluctuations presents a Lorentzian spectrum and the amplitude of fluctuations shows a significant non-Gaussian behavior in the prebreakdown region. These results compare well with electrical breakdown measurements in thin films of composites and of other conducting materials.

  1. Counterflow Regolith Heat Exchanger

    Science.gov (United States)

    Zubrin, Robert; Jonscher, Peter

    2013-01-01

    A problem exists in reducing the total heating power required to extract oxygen from lunar regolith. All such processes require heating a great deal of soil, and the heat energy is wasted if it cannot be recycled from processed material back into new material. The counterflow regolith heat exchanger (CoRHE) is a device that transfers heat from hot regolith to cold regolith. The CoRHE is essentially a tube-in-tube heat exchanger with internal and external augers attached to the inner rotating tube to move the regolith. Hot regolith in the outer tube is moved in one direction by a right-hand - ed auger, and the cool regolith in the inner tube is moved in the opposite direction by a left-handed auger attached to the inside of the rotating tube. In this counterflow arrangement, a large fraction of the heat from the expended regolith is transferred to the new regolith. The spent regolith leaves the heat exchanger close to the temperature of the cold new regolith, and the new regolith is pre-heated close to the initial temperature of the spent regolith. Using the CoRHE can reduce the heating requirement of a lunar ISRU system by 80%, reducing the total power consumption by a factor of two. The unique feature of this system is that it allows for counterflow heat exchange to occur between solids, instead of liquids or gases, as is commonly done. In addition, in variants of this concept, the hydrogen reduction can be made to occur within the counterflow heat exchanger itself, enabling a simplified lunar ISRU (in situ resource utilization) system with excellent energy economy and continuous nonbatch mode operation.

  2. Melihat Bisnis Bias Kapital Media: Asumsi Aksiologi Dan Ontologis Sederhana

    OpenAIRE

    Kurnia, Septiawan Santana

    2003-01-01

    Idealnya, media massa menjadi pilar demokrasi, juga mencerahkan dan memberdayakan warga negara. Akan tetapi, di Indonesia, media massa seringkali mengalami bias: bias kapital, bias kekuasaan, bias kepentingan wartawan sendiri, dan bias-bias lainnya. Contoh sederhana, rubrik Advertorial di media cetak. Rubrik itu dikemas seperti berita, padahal ikLan. Sejalan dengan itu, muncul pula fenomena di mana iklan tidak dipagari oLeh fire wall, untuk membedakannya dengan teks berita. Pengemasan iklan i...

  3. A corrosive resistant heat exchanger

    Science.gov (United States)

    Richlen, S.L.

    1987-08-10

    A corrosive and erosive resistant heat exchanger which recovers heat from a contaminated heat stream. The heat exchanger utilizes a boundary layer of innocuous gas, which is continuously replenished, to protect the heat exchanger surface from the hot contaminated gas. The innocuous gas is pumped through ducts or perforations in the heat exchanger wall. Heat from the heat stream is transferred by radiation to the heat exchanger wall. Heat is removed from the outer heat exchanger wall by a heat recovery medium. 3 figs., 3 tabs.

  4. Analytical applications of ion exchangers

    CERN Document Server

    Inczédy, J

    1966-01-01

    Analytical Applications of Ion Exchangers presents the laboratory use of ion-exchange resins. This book discusses the development in the analytical application of ion exchangers. Organized into 10 chapters, this book begins with an overview of the history and significance of ion exchangers for technical purposes. This text then describes the properties of ion exchangers, which are large molecular water-insoluble polyelectrolytes having a cross-linked structure that contains ionic groups. Other chapters consider the theories concerning the operation of ion-exchange resins and investigate th

  5. Establishing an institutional therapeutic apheresis registry.

    Science.gov (United States)

    Mann, Steven A; McCleskey, Brandi; Marques, Marisa B; Adamski, Jill

    2016-12-01

    Apheresis was first performed as a therapeutic procedure in the 1950s. The first national therapeutic apheresis (TA) registry was established in Canada in 1981 and other national registries followed, including two attempts at establishing an international TA registry. There is no national registry in the United States. Our large, academic, tertiary hospital has a very active TA service. We created a TA database to track all procedures performed by the apheresis service by transferring data from paper appointment logs and the electronic medical records into a Microsoft Access database. Retrospective data from each TA procedure performed at UAB from January 1, 2003 through December 31, 2012 were entered, including the type of procedure, indication, date, and patient demographics. Microsoft Excel was used for data analysis. During the 10-year period, our TA service treated 1,060 patients and performed 11,718 procedures. Of these patients, 70% received therapeutic plasma exchange (TPE), 21% received extracorporeal photopheresis (ECP), 4.5% received red cell exchange (RCE), 4.2% received leukocytapheresis, and 0.6% underwent platelet depletion. Among the procedures, 54% were TPEs, 44% were ECPs, 1.3% were RCEs, 0.5% were leukocytaphereses, and 0.1% were platelet depletions. According to the current literature, national and international TA use is underreported. We believe that the UAB TA registry provides useful information about TA practices in our region and can serve as a model for other institutions. Furthermore, data from multiple institutional registries can be used for clinical research to increase the available evidence for the role of TA in various conditions. J. Clin. Apheresis 31:516-522, 2016. © 2015 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  6. Beyond assembly bias: exploring secondary halo biases for cluster-size haloes

    Science.gov (United States)

    Mao, Yao-Yuan; Zentner, Andrew R.; Wechsler, Risa H.

    2018-03-01

    Secondary halo bias, commonly known as `assembly bias', is the dependence of halo clustering on a halo property other than mass. This prediction of the Λ Cold Dark Matter cosmology is essential to modelling the galaxy distribution to high precision and interpreting clustering measurements. As the name suggests, different manifestations of secondary halo bias have been thought to originate from halo assembly histories. We show conclusively that this is incorrect for cluster-size haloes. We present an up-to-date summary of secondary halo biases of high-mass haloes due to various halo properties including concentration, spin, several proxies of assembly history, and subhalo properties. While concentration, spin, and the abundance and radial distribution of subhaloes exhibit significant secondary biases, properties that directly quantify halo assembly history do not. In fact, the entire assembly histories of haloes in pairs are nearly identical to those of isolated haloes. In general, a global correlation between two halo properties does not predict whether or not these two properties exhibit similar secondary biases. For example, assembly history and concentration (or subhalo abundance) are correlated for both paired and isolated haloes, but follow slightly different conditional distributions in these two cases. This results in a secondary halo bias due to concentration (or subhalo abundance), despite the lack of assembly bias in the strict sense for cluster-size haloes. Due to this complexity, caution must be exercised in using any one halo property as a proxy to study the secondary bias due to another property.

  7. Placebo effect studies are susceptible to response bias and to other types of biases

    DEFF Research Database (Denmark)

    Hróbjartsson, Asbjørn; Kaptchuk, Ted J; Miller, Franklin G

    2011-01-01

    Investigations of the effect of placebo are often challenging to conduct and interpret. The history of placebo shows that assessment of its clinical significance has a real potential to be biased. We analyze and discuss typical types of bias in studies on placebo.......Investigations of the effect of placebo are often challenging to conduct and interpret. The history of placebo shows that assessment of its clinical significance has a real potential to be biased. We analyze and discuss typical types of bias in studies on placebo....

  8. Investigation of hydrogen isotopic exchange catalysed by palladium phosphine complexes

    International Nuclear Information System (INIS)

    Zudin, V.N.; Rogov, V.A.; Likholobov, V.A.

    1985-01-01

    Basic regularities of the isotopic exchange reaction between molecular and protonated forms of hydrogen in the palladium phosphine complex system in CF 3 COOH aqueous solutions are studied by the radiochemical and mass-spectrometric methods using deuterium and tritium isotopes. The influences of C 2 H 4 and CO presence on the reaction proceeding are also studied by the same methods. It is established that bis(triphenyl phosphine)-bis(trifluoroacetate) palladium acts as a catalyst for hydrogen isotopic exchange. Hydrogen exchange runs through Pd hydride complex synthesis and decomposition, the hydrogen atom being capable of exchanging with solvent protons. Ethylene introduction into the system reduces the rate of the hydrogen exchange reaction, and the presence of the ethylene mixture and the carbon oxide inhibited it completely

  9. Implicit Bias in Pediatric Academic Medicine.

    Science.gov (United States)

    Johnson, Tiffani J; Ellison, Angela M; Dalembert, George; Fowler, Jessica; Dhingra, Menaka; Shaw, Kathy; Ibrahim, Said

    2017-01-01

    Despite known benefits of diversity, certain racial/ethnic groups remain underrepresented in academic pediatrics. Little research exists regarding unconscious racial attitudes among pediatric faculty responsible for decisions on workforce recruitment and retention in academia. This study sought to describe levels of unconscious racial bias and perceived barriers to minority recruitment and retention among academic pediatric faculty leaders. Authors measured unconscious racial bias in a sample of pediatric faculty attending diversity workshops conducted at local and national meetings in 2015. A paper version of the validated Implicit Association Test (IAT) measured unconscious racial bias. Subjects also reported perceptions about minority recruitment and retention. Of 68 eligible subjects approached, 58 (85%) consented and completed the survey with IAT. Of participants, 83% had leadership roles and 93% were involved in recruitment. Participants had slight pro-white/anti-black bias on the IAT (M = 0.28, SD = 0.49). There were similar IAT scores among participants in leadership roles (M = 0.33, SD = 0.47) and involved in recruitment (M = 0.28, SD = 0.43). Results did not differ when comparing participants in local workshops to the national workshop (n = 36, M = 0.29, SD = 0.40 and n = 22, M = 0.27, SD = 0.49 respectively; p = 0.88). Perceived barriers to minority recruitment and retention included lack of minority mentors, poor recruitment efforts, and lack of qualified candidates. Unconscious pro-white/anti-black racial bias was identified in this sample of academic pediatric faculty and leaders. Further research is needed to examine how unconscious bias impacts decisions in academic pediatric workforce recruitment. Addressing unconscious bias and perceived barriers to minority recruitment and retention represent opportunities to improve diversity efforts. Copyright © 2017 National Medical Association. All rights reserved.

  10. The Metaphysics of Economic Exchanges

    Directory of Open Access Journals (Sweden)

    Massin Olivier

    2017-05-01

    Full Text Available What are economic exchanges? The received view has it that exchanges are mutual transfers of goods motivated by inverse valuations thereof. As a corollary, the standard approach treats exchanges of services as a subspecies of exchanges of goods. We raise two objections against this standard approach. First, it is incomplete, as it fails to take into account, among other things, the offers and acceptances that lie at the core of even the simplest cases of exchanges. Second, it ultimately fails to generalize to exchanges of services, in which neither inverse preferences nor mutual transfers hold true. We propose an alternative definition of exchanges, which treats exchanges of goods as a special case of exchanges of services and which builds in offers and acceptances. According to this theory: (i The valuations motivating exchanges are propositional and convergent rather than objectual and inverse; (ii All exchanges of goods involve exchanges of services/actions, but not the reverse; (iii Offers and acceptances, together with the contractual obligations and claims they bring about, lie at the heart of all cases of exchange.

  11. Gas exchange measurements in natural systems

    International Nuclear Information System (INIS)

    Broecker, W.S.; Peng, T.H.

    1983-01-01

    Direct knowledge of the rates of gas exchange in lakes and the ocean is based almost entirely on measurements of the isotopes 14 C, 222 Rn and 3 He. The distribution of natural radiocarbon has yielded the average rate of CO 2 exchange for the ocean and for several closed basin lakes. That of bomb produced radiocarbon has been used in the same systems. The 222 Rn to 226 Ra ratio in open ocean surface water has been used to give local short term gas exchange rates. The radon method generally cannot be used in lakes, rivers, estuaries or shelf areas because of the input of radon from sediments. A few attempts have been made to use the excess 3 He produced by decay of bomb produced tritium in lakes to give gas transfer rates. The uncertainty in the molecular diffusivity of helium and in the diffusivity dependence of the rate of gas transfer holds back the application of this method. A few attempts have been made to enrich the surface waters of small lakes with 226 Ra and 3 H in order to allow the use of the 222 Rn and 3 He methods. While these studies give broadly concordant results, many questions remain unanswered. The wind velocity dependence of gas exchange rate has yet to be established in field studies. The dependence of gas exchange rate on molecular diffusivity also remains in limbo. Finally, the degree of enhancement of CO 2 exchange through chemical reactions has been only partially explored. 49 references, 2 figures, 2 tables

  12. Foreign Exchange Risk Premium Determinants: Case of Armenia

    OpenAIRE

    Tigran Poghosyan; Evzen Kocenda

    2006-01-01

    This paper studies foreign exchange risk premium using the uncovered interest rate parity framework in a model economy. The analysis is performed using weekly data on foreign and domestic currency deposits in the Armenian banking system. Results of the study indicate that contrary to the established view there is a positive correspondence between exchange rate depreciation and interest rate differentials. Further, it is shown that a systematic positive risk premium required by economic agents...

  13. Data Exchange Inventory (DEXI) System

    Data.gov (United States)

    Social Security Administration — DEXI is an intranet application used by SSA users to track all incoming and outgoing data exchanges between SSA and our data exchange partners. Information such as...

  14. Exchange-biased planar Hall effect sensor optimized for biosensor applications

    DEFF Research Database (Denmark)

    Damsgaard, Christian Danvad; Freitas, S.C.; Freitas, P.P.

    2008-01-01

    and that the thicker film will have a higher signal as well as a lower noise. It is estimated that the signal-to-noise ratio for bead detection increases by a factor 2.1 when t is increased from 20 to 50 nm and hence a higher t is beneficial for biosensor applications. This is exemplified with calculations on M-280...

  15. Effects of imaging gradients in sequences with varying longitudinal storage time-Case of diffusion exchange imaging.

    Science.gov (United States)

    Lasič, Samo; Lundell, Henrik; Topgaard, Daniel; Dyrby, Tim B

    2018-04-01

    To illustrate the potential bias caused by imaging gradients in correlation MRI sequences using longitudinal magnetization storage (LS) and examine the case of filter exchange imaging (FEXI) yielding maps of the apparent exchange rate (AXR). The effects of imaging gradients in FEXI were observed on yeast cells. To analyze the AXR bias, signal evolution was calculated by applying matrix exponential operators. A sharp threshold for the slice thickness was identified, below which the AXR is increasingly underestimated. The bias can be understood in terms of an extended low-pass diffusion filtering during the LS interval, which is more pronounced at lower exchange rates. For a total exchange rate constant larger than 1 s -1 , the AXR bias is expected to be negligible when slices thicker than 2.5 mm are used. In correlation experiments like FEXI, relying on LS with variable duration, imaging gradients may cause disrupting effects that cannot be easily mitigated and should be carefully considered for unbiased results. In typical clinical applications of FEXI, the imaging gradients are expected to cause a negligible AXR bias. However, the AXR bias may be significant in preclinical settings or whenever thin imaging slices are used. Magn Reson Med 79:2228-2235, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  16. Electrostatically biased binding of kinesin to microtubules.

    Directory of Open Access Journals (Sweden)

    Barry J Grant

    2011-11-01

    Full Text Available The minimum motor domain of kinesin-1 is a single head. Recent evidence suggests that such minimal motor domains generate force by a biased binding mechanism, in which they preferentially select binding sites on the microtubule that lie ahead in the progress direction of the motor. A specific molecular mechanism for biased binding has, however, so far been lacking. Here we use atomistic Brownian dynamics simulations combined with experimental mutagenesis to show that incoming kinesin heads undergo electrostatically guided diffusion-to-capture by microtubules, and that this produces directionally biased binding. Kinesin-1 heads are initially rotated by the electrostatic field so that their tubulin-binding sites face inwards, and then steered towards a plus-endwards binding site. In tethered kinesin dimers, this bias is amplified. A 3-residue sequence (RAK in kinesin helix alpha-6 is predicted to be important for electrostatic guidance. Real-world mutagenesis of this sequence powerfully influences kinesin-driven microtubule sliding, with one mutant producing a 5-fold acceleration over wild type. We conclude that electrostatic interactions play an important role in the kinesin stepping mechanism, by biasing the diffusional association of kinesin with microtubules.

  17. Non-Gaussian halo assembly bias

    International Nuclear Information System (INIS)

    Reid, Beth A.; Verde, Licia; Dolag, Klaus; Matarrese, Sabino; Moscardini, Lauro

    2010-01-01

    The strong dependence of the large-scale dark matter halo bias on the (local) non-Gaussianity parameter, f NL , offers a promising avenue towards constraining primordial non-Gaussianity with large-scale structure surveys. In this paper, we present the first detection of the dependence of the non-Gaussian halo bias on halo formation history using N-body simulations. We also present an analytic derivation of the expected signal based on the extended Press-Schechter formalism. In excellent agreement with our analytic prediction, we find that the halo formation history-dependent contribution to the non-Gaussian halo bias (which we call non-Gaussian halo assembly bias) can be factorized in a form approximately independent of redshift and halo mass. The correction to the non-Gaussian halo bias due to the halo formation history can be as large as 100%, with a suppression of the signal for recently formed halos and enhancement for old halos. This could in principle be a problem for realistic galaxy surveys if observational selection effects were to pick galaxies occupying only recently formed halos. Current semi-analytic galaxy formation models, for example, imply an enhancement in the expected signal of ∼ 23% and ∼ 48% for galaxies at z = 1 selected by stellar mass and star formation rate, respectively

  18. Compact cryocooler heat exchangers

    International Nuclear Information System (INIS)

    Luna, J.; Frederking, T.H.K.

    1991-01-01

    Compact heat exchangers are subject to different constraints as a room temperature gas is cooled down by a cold stream returning from a JT valve (or a similar cryoprocess component). In particular, the optimization of exchangers for liquid helium systems has to cover a wide range in temperature and density of the fluid. In the present work we address the following thermodynamic questions: 1. The optimization of intermediate temperatures which optimize stage operation (a stage is assumed to have a constant cross section); 2. The optimum temperature difference available for best overall economic performance values. The results are viewed in the context of porous media concepts applied to rather low speeds of fluid flow in narrow passages. In this paper examples of fluid/solid constraints imposed in this non-classical low temperature area are presented

  19. Lipid exchange by ultracentrifugation

    DEFF Research Database (Denmark)

    Drachmann, Nikolaj Düring; Olesen, Claus

    2014-01-01

    Lipids play an important role in maintaining P-type ATPase structure and function, and often they are crucial for ATPase activity. When the P-type ATPases are in the membrane, they are surrounded by a mix of different lipids species with varying aliphatic chain lengths and saturation......, and the complex interplay between the lipids and the P-type ATPases are still not well understood. We here describe a robust method to exchange the majority of the lipids surrounding the ATPase after solubilisation and/or purification with a target lipid of interest. The method is based on an ultracentrifugation...... step, where the protein sample is spun through a dense buffer containing large excess of the target lipid, which results in an approximately 80-85 % lipid exchange. The method is a very gently technique that maintains protein folding during the process, hence allowing further characterization...

  20. Heat exchanger tube mounts

    Science.gov (United States)

    Wolowodiuk, W.; Anelli, J.; Dawson, B.E.

    1974-01-01

    A heat exchanger in which tubes are secured to a tube sheet by internal bore welding is described. The tubes may be moved into place in preparation for welding with comparatively little trouble. A number of segmented tube support plates are provided which allow a considerable portion of each of the tubes to be moved laterally after the end thereof has been positioned in preparation for internal bore welding to the tube sheet. (auth)

  1. Exchange rate rebounds after foreign exchange market interventions

    Science.gov (United States)

    Hoshikawa, Takeshi

    2017-03-01

    This study examined the rebounds in the exchange rate after foreign exchange intervention. When intervention is strongly effective, the exchange rate rebounds at next day. The effect of intervention is reduced slightly by the rebound after the intervention. The exchange rate might have been 67.12-77.47 yen to a US dollar without yen-selling/dollar-purchasing intervention of 74,691,100 million yen implemented by the Japanese government since 1991, in comparison to the actual exchange rate was 103.19 yen to the US dollar at the end of March 2014.

  2. The exchangeability of shape

    Directory of Open Access Journals (Sweden)

    Kaba Dramane

    2010-10-01

    Full Text Available Abstract Background Landmark based geometric morphometrics (GM allows the quantitative comparison of organismal shapes. When applied to systematics, it is able to score shape changes which often are undetectable by traditional morphological studies and even by classical morphometric approaches. It has thus become a fast and low cost candidate to identify cryptic species. Due to inherent mathematical properties, shape variables derived from one set of coordinates cannot be compared with shape variables derived from another set. Raw coordinates which produce these shape variables could be used for data exchange, however they contain measurement error. The latter may represent a significant obstacle when the objective is to distinguish very similar species. Results We show here that a single user derived dataset produces much less classification error than a multiple one. The question then becomes how to circumvent the lack of exchangeability of shape variables while preserving a single user dataset. A solution to this question could lead to the creation of a relatively fast and inexpensive systematic tool adapted for the recognition of cryptic species. Conclusions To preserve both exchangeability of shape and a single user derived dataset, our suggestion is to create a free access bank of reference images from which one can produce raw coordinates and use them for comparison with external specimens. Thus, we propose an alternative geometric descriptive system that separates 2-D data gathering and analyzes.

  3. Scraped surface heat exchangers.

    Science.gov (United States)

    Rao, Chetan S; Hartel, Richard W

    2006-01-01

    Scraped surface heat exchangers (SSHEs) are commonly used in the food, chemical, and pharmaceutical industries for heat transfer, crystallization, and other continuous processes. They are ideally suited for products that are viscous, sticky, that contain particulate matter, or that need some degree of crystallization. Since these characteristics describe a vast majority of processed foods, SSHEs are especially suited for pumpable food products. During operation, the product is brought in contact with a heat transfer surface that is rapidly and continuously scraped, thereby exposing the surface to the passage of untreated product. In addition to maintaining high and uniform heat exchange, the scraper blades also provide simultaneous mixing and agitation. Heat exchange for sticky and viscous foods such as heavy salad dressings, margarine, chocolate, peanut butter, fondant, ice cream, and shortenings is possible only by using SSHEs. High heat transfer coefficients are achieved because the boundary layer is continuously replaced by fresh material. Moreover, the product is in contact with the heating surface for only a few seconds and high temperature gradients can be used without the danger of causing undesirable reactions. SSHEs are versatile in the use of heat transfer medium and the various unit operations that can be carried out simultaneously. This article critically reviews the current understanding of the operations and applications of SSHEs.

  4. Hydrogen isotope exchange reactions

    International Nuclear Information System (INIS)

    Jones, J.R.

    1980-01-01

    The two most widely used methods for following hydrogen isotope exchange reactions, namely dedeuteriation and detritiation, involve in the first place the synthesis of an appropriately labelled compound. Rates of dedeuteriation are usually followed by measuring changes in the 1 H n.m.r. spectrum of the substrate (examples are given); the method not only gives the rate but also the site(s) of exchange. It is limited to rather slow reactions and is not as accurate as some of the other methods. The development of deuterium n.m.r. spectroscopy means that changes in the 2 H n.m.r. spectrum can also be used to measure rates of dedeuteriation. The development of liquid scintillation counting greatly eased the problem of how to detect weak β emitters; the attractions of tritium as a tracer were thereby much enhanced. Nowadays the study of rates of detritiation constitutes one of the most versatile and accurate methods of following hydrogen isotope exchange. Examples of the technique are given. (U.K.)

  5. Paste heat exchange

    Energy Technology Data Exchange (ETDEWEB)

    1943-07-30

    The subject of coal paste heat exchangers is discussed in this letter report from Gelsenberg A.G. to I.G. Farbenindustrie A.G. Gelsenberg had given little consideration to the heating of coal paste by means of regeneration (heat exchange) because of the lack of experience in paste regeneration with bituminous coal, especially at 700 atmospheres. At the I.G. Farben plant at Poelitz, paste regeneration was carried out so that low concentration coal paste was heated in the regenerator together with the process gas, and the remaining coal was fed into the cold pass of the preheater in a thicker paste. Later tests proved this process viable. Gelsenberg heated normal coal paste and the gas in heat exchangers with the goal of relieving the preheater. Good results were achieved without change in design. The coal paste was heated with process gas in the regenerator at up to 315 degrees with constant pressure difference, so that after three months no decrease in K-values and no deposition or thickening was observed. Through the omission of paste gas, the pressure difference of the system became more constant and did not rise above the former level. The temperature also was more controllable, the chamber smoother running. Principal thermal data are given in a table. 1 table, 1 graph.

  6. Timing Foreign Exchange Markets

    Directory of Open Access Journals (Sweden)

    Samuel W. Malone

    2016-03-01

    Full Text Available To improve short-horizon exchange rate forecasts, we employ foreign exchange market risk factors as fundamentals, and Bayesian treed Gaussian process (BTGP models to handle non-linear, time-varying relationships between these fundamentals and exchange rates. Forecasts from the BTGP model conditional on the carry and dollar factors dominate random walk forecasts on accuracy and economic criteria in the Meese-Rogoff setting. Superior market timing ability for large moves, more than directional accuracy, drives the BTGP’s success. We explain how, through a model averaging Monte Carlo scheme, the BTGP is able to simultaneously exploit smoothness and rough breaks in between-variable dynamics. Either feature in isolation is unable to consistently outperform benchmarks throughout the full span of time in our forecasting exercises. Trading strategies based on ex ante BTGP forecasts deliver the highest out-of-sample risk-adjusted returns for the median currency, as well as for both predictable, traded risk factors.

  7. Exchange of Standardized Flight Dynamics Data

    Science.gov (United States)

    Martin-Mur, Tomas J.; Berry, David; Flores-Amaya, Felipe; Folliard, J.; Kiehling, R.; Ogawa, M.; Pallaschke, S.

    2004-01-01

    Spacecraft operations require the knowledge of the vehicle trajectory and attitude and also that of other spacecraft or natural bodies. This knowledge is normally provided by the Flight Dynamics teams of the different space organizations and, as very often spacecraft operations involve more than one organization, this information needs to be exchanged between Agencies. This is why the Navigation Working Group within the CCSDS (Consultative Committee for Space Data Systems), has been instituted with the task of establishing standards for the exchange of Flight Dynamics data. This exchange encompasses trajectory data, attitude data, and tracking data. The Navigation Working Group includes regular members and observers representing the participating Space Agencies. Currently the group includes representatives from CNES, DLR, ESA, NASA and JAXA. This Working Group meets twice per year in order to devise standardized language, methods, and formats for the description and exchange of Navigation data. Early versions of some of these standards have been used to support mutual tracking of ESA and NASA interplanetary spacecraft, especially during the arrival of the 2003 missions to Mars. This paper provides a summary of the activities carried out by the group, briefly outlines the current and envisioned standards, describes the tests and operational activities that have been performed using the standards, and lists and discusses the lessons learned from these activities.

  8. Thinking in Black and White: Conscious thought increases racially biased judgments through biased face memory

    NARCIS (Netherlands)

    Strick, M.A.; Stoeckart, P.F.; Dijksterhuis, A.J.

    2015-01-01

    It is a common research finding that conscious thought helps people to avoid racial discrimination. These three experiments, however, illustrate that conscious thought may increase biased face memory, which leads to increased judgment bias (i.e., preferring White to Black individuals). In

  9. Racial and Ethnic Bias in Psychological Tests: Divergent Implications of Two Definitions of Test Bias

    Science.gov (United States)

    Schmidt, Frank L.; Hunter, John E.

    1974-01-01

    Two competing definitions of test fairness and their differing implications are explained and illustrated, and data from a number of published studies on test bias are reanalyzed; the focus is on unfair bias that may exist in tests that are approximately equally valid for both majority and minority groups. (Author/JM)

  10. Research bias in judgement bias studies : A systematic review of valuation judgement literature

    NARCIS (Netherlands)

    Klamer, Pim; Bakker, C.; Gruis, Vincent

    2017-01-01

    Valuation judgement bias has been a research topic for several years due to its proclaimed effect on valuation accuracy. However, little is known on the emphasis of literature on judgement bias, with regard to, for instance, research methodologies, research context and robustness of research

  11. Research bias in judgement bias studies : a systematic review of valuation judgement literature

    NARCIS (Netherlands)

    Klamer, Pim; Bakker, Cok; Gruis, V.H.

    2017-01-01

    Valuation judgement bias has been a research topic for several years due to its proclaimed effect on valuation accuracy. However, little is known on the emphasis of literature on judgement bias, with regard to, for instance, research methodologies, research context and robustness of research

  12. Toward a synthesis of cognitive biases: how noisy information processing can bias human decision making.

    Science.gov (United States)

    Hilbert, Martin

    2012-03-01

    A single coherent framework is proposed to synthesize long-standing research on 8 seemingly unrelated cognitive decision-making biases. During the past 6 decades, hundreds of empirical studies have resulted in a variety of rules of thumb that specify how humans systematically deviate from what is normatively expected from their decisions. Several complementary generative mechanisms have been proposed to explain those cognitive biases. Here it is suggested that (at least) 8 of these empirically detected decision-making biases can be produced by simply assuming noisy deviations in the memory-based information processes that convert objective evidence (observations) into subjective estimates (decisions). An integrative framework is presented to show how similar noise-based mechanisms can lead to conservatism, the Bayesian likelihood bias, illusory correlations, biased self-other placement, subadditivity, exaggerated expectation, the confidence bias, and the hard-easy effect. Analytical tools from information theory are used to explore the nature and limitations that characterize such information processes for binary and multiary decision-making exercises. The ensuing synthesis offers formal mathematical definitions of the biases and their underlying generative mechanism, which permits a consolidated analysis of how they are related. This synthesis contributes to the larger goal of creating a coherent picture that explains the relations among the myriad of seemingly unrelated biases and their potential psychological generative mechanisms. Limitations and research questions are discussed.

  13. Placebo effect studies are susceptible to response bias and to other types of biases

    DEFF Research Database (Denmark)

    Hróbjartsson, Asbjørn; Kaptchuk, Ted J; Miller, Franklin G

    2011-01-01

    Investigations of the effect of placebo are often challenging to conduct and interpret. The history of placebo shows that assessment of its clinical significance has a real potential to be biased. We analyze and discuss typical types of bias in studies on placebo....

  14. Scientific-technical exchange of experiences between Germany and the GUS, the Baltic and MOE states, and central Asia and other regions. Workshop and establishment of a common knowledge base for nuclear safety and security. Final report; Wissenschaftlich-technischer Erfahrungsaustausch Deutschlands mit der GUS, den Baltischen und den MOE-Staaten sowie Laendern Zentralasiens und anderer Regionen. Arbeitstreffen und Schaffung gemeinsamer Wissensbasen fuer nukleare Sicherheit und Sicherung. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Dabrowski, Anna

    2017-03-15

    The report on the workshop concerning scientific-technical exchange of experiences between Germany and the GUS, the Baltic and MOE states, and central Asia and other regions includes the following issues: Results an d success of know-how transfer from West to East, topical issues for mutual exchange of experience, scope of the project, concept of the realization of mutual exchange of experiences. The emphasis of the workshop covered the following issues: emergency preparedness, international requirements concerning nuclear safety and radiation protection, transport of radioactive wastes and communication in nuclear technology.

  15. A system for biasing a differential amplifier

    International Nuclear Information System (INIS)

    Barbier, Daniel; Ittel, J.M.; Poujois, Robert

    1975-01-01

    This invention concerns a system for biasing a differential amplifier. It particularly applies to the integrated differential amplifiers designed with MOS field effect transistors. Variations in the technological parameters may well cause the amplifying transistors to work outside their usual operational area, in other words outside the linear part of the transfer characteristic. To ensure that these transistors function correctly, it is necessary that the value of the voltage difference at the output be equally null. To do this and to centre on the so called 'rest' point of the amplifier transfer charateristic, the condition will be set that the output potentials of each amplifier transistor should have a zero value or a constant value as sum. With this in view, the bias on the source (generally a transistor powered by its grid bias voltage) supplying current to the two amplifying transistors fitted in parallel, is permanently adjusted in a suitable manner [fr

  16. Reference List About Implicit and Unconscious Bias

    DEFF Research Database (Denmark)

    Munar, Ana Maria; Villeseche, Florence; Weidemann, Cecilie Dam

    to publications accessible through the CBS library website and/or specifications of where and how to access each publication. In addition, as part of this effort and in line with the task list of the Council for Diversity and Inclusion, the report “Gender and Leadership Practices at Copenhagen Business School......The compilation of this reference list is one of the initiatives of the action plan developed by the Council for Diversity and Inclusion at Copenhagen Business School (CBS). This reference list is the first in a series of efforts initiated by this Council to develop an academic resource pool...... and knowledge base on diversity- and inclusion-related topics. An implicit and/or unconscious bias is a bias that we are unaware of and is therefore expressed unwillingly and unknowingly. As recent studies on implicit bias indicate “we now know that the operation of prejudice and stereotyping in social judgment...

  17. Recognition bias and the physical attractiveness stereotype.

    Science.gov (United States)

    Rohner, Jean-Christophe; Rasmussen, Anders

    2012-06-01

    Previous studies have found a recognition bias for information consistent with the physical attractiveness stereotype (PAS), in which participants believe that they remember that attractive individuals have positive qualities and that unattractive individuals have negative qualities, regardless of what information actually occurred. The purpose of this research was to examine whether recognition bias for PAS congruent information is replicable and invariant across a variety of conditions (i.e. generalizable). The effects of nine different moderator variables were examined in two experiments. With a few exceptions, the effect of PAS congruence on recognition bias was independent of the moderator variables. The results suggest that the tendency to believe that one remembers information consistent with the physical attractiveness stereotype is a robust phenomenon. © 2012 The Authors. Scandinavian Journal of Psychology © 2012 The Scandinavian Psychological Associations.

  18. Covariation bias in panic-prone individuals.

    Science.gov (United States)

    Pauli, P; Montoya, P; Martz, G E

    1996-11-01

    Covariation estimates between fear-relevant (FR; emergency situations) or fear-irrelevant (FI; mushrooms and nudes) stimuli and an aversive outcome (electrical shock) were examined in 10 high-fear (panic-prone) and 10 low-fear respondents. When the relation between slide category and outcome was random (illusory correlation), only high-fear participants markedly overestimated the contingency between FR slides and shocks. However, when there was a high contingency of shocks following FR stimuli (83%) and a low contingency of shocks following FI stimuli (17%), the group difference vanished. Reversal of contingencies back to random induced a covariation bias for FR slides in high- and low-fear respondents. Results indicate that panic-prone respondents show a covariation bias for FR stimuli and that the experience of a high contingency between FR slides and aversive outcomes may foster such a covariation bias even in low-fear respondents.

  19. Using Machine Learning to Predict MCNP Bias

    Energy Technology Data Exchange (ETDEWEB)

    Grechanuk, Pavel Aleksandrovi [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2018-01-09

    For many real-world applications in radiation transport where simulations are compared to experimental measurements, like in nuclear criticality safety, the bias (simulated - experimental keff) in the calculation is an extremely important quantity used for code validation. The objective of this project is to accurately predict the bias of MCNP6 [1] criticality calculations using machine learning (ML) algorithms, with the intention of creating a tool that can complement the current nuclear criticality safety methods. In the latest release of MCNP6, the Whisper tool is available for criticality safety analysts and includes a large catalogue of experimental benchmarks, sensitivity profiles, and nuclear data covariance matrices. This data, coming from 1100+ benchmark cases, is used in this study of ML algorithms for criticality safety bias predictions.

  20. The overconfidence bias and CEO: literature review

    Directory of Open Access Journals (Sweden)

    Tereza Čuláková

    2018-06-01

    Full Text Available This systematic review deals the overconfidence bias. It is a cognitive bias which is described as the tendency of people to overestimate their abilities, prospects and chances of success. For the purpose of the research we chose to examine the influence of overconfidence bias on CEOs’ decision-making and their work in a company. The systematic review followed three main situations revealing CEOs’ overconfidence within a company – dividend policy, innovative processes and hiring new employees. According to the review of the literature, there is no obvious connection between CEOs’ overconfidence and a generous dividend policy. However, as for the innovative processes, it seems that overconfident CEOs are more willing to support a higher number of innovations. In the final situation, the literature does not yet provide decisive guidance on the relationship between CEOs’ overconfidence and the process of managing employees and hiring new ones.

  1. Improved detection in CDMA for biased sources

    Energy Technology Data Exchange (ETDEWEB)

    Efraim, Hadar [Minerva Center and Department of Physics, Bar-Ilan University, Ramat-Gan 52900 (Israel); Yacov, Nadav [Minerva Center and Department of Physics, Bar-Ilan University, Ramat-Gan 52900 (Israel); Shental, Ori [Center for Magnetic Recording Research (CMRR), University of California, San Diego (UCSD), 9500 Gilman Drive, La Jolla, CA 92093 (United States); Kanter, Ido [Minerva Center and Department of Physics, Bar-Ilan University, Ramat-Gan 52900 (Israel); Saad, David [Neural Computing Research Group, Aston University, Birmingham B4 7ET (United Kingdom)

    2007-08-17

    We consider the detection of biased information sources in the ubiquitous code-division multiple-access (CDMA) scheme. We propose a simple modification to both the popular single-user matched-filter detector and a recently introduced near-optimal message-passing-based multiuser detector. This modification allows for detecting modulated biased sources directly with no need for source coding. Analytical results and simulations with excellent agreement are provided, demonstrating substantial improvement in bit error rate in comparison with the unmodified detectors and the alternative of source compression. The robustness of error-performance improvement is shown under practical model settings, including bias estimation mismatch and finite-length spreading codes.

  2. Magnetoresistance of nanogranular Ni/NiO controlled by exchange anisotropy

    International Nuclear Information System (INIS)

    Del Bianco, L.; Spizzo, F.; Tamisari, M.; Allia, P.

    2013-01-01

    A link between exchange anisotropy and magnetoresistance has been found to occur in a Ni/NiO sample consisting of Ni nanocrystallites (mean size ∼13 nm, Ni content ∼33 vol%) dispersed in a NiO matrix. This material shows metallic-type electric conduction and isotropic spin-dependent magnetoresistance as well as exchange bias effect. The latter is the outcome of an exchange anisotropy arising from the contact interaction between the Ni phase and the NiO matrix. Combined analysis of magnetization M(H) and magnetoresistance MR(H) loops measured in the 5–250 K temperature range after zero-field-cooling (ZFC) and after field-cooling (FC) from 300 K reveals that the magnetoresistance is influenced by exchange anisotropy, which is triggered by the FC process and can be modified in strength by varying the temperature. Compared to the ZFC case, the exchange anisotropy produces a horizontal shift of the FC MR(H) loop along with a reduction of the MR response associated to the reorientation of the Ni moments. A strict connection between magnetoresistance and remanent magnetization of FC loops on one side and the exchange field on the other, ruled by exchange anisotropy, is indicated. - Highlights: • Nanogranular Ni/NiO with giant magnetoresistance (MR) and exchange bias effect. • Exchange anisotropy produces a shift of the field-cooled MR(H) loop and reduces MR. • MR, remanence of field-cooled loops and exchange field are three correlated quantities. • It is possible to control MR of nanogranular systems through the exchange anisotropy

  3. Recursive bias estimation and L2 boosting

    Energy Technology Data Exchange (ETDEWEB)

    Hengartner, Nicolas W [Los Alamos National Laboratory; Cornillon, Pierre - Andre [INRA, FRANCE; Matzner - Lober, Eric [RENNE, FRANCE

    2009-01-01

    This paper presents a general iterative bias correction procedure for regression smoothers. This bias reduction schema is shown to correspond operationally to the L{sub 2} Boosting algorithm and provides a new statistical interpretation for L{sub 2} Boosting. We analyze the behavior of the Boosting algorithm applied to common smoothers S which we show depend on the spectrum of I - S. We present examples of common smoother for which Boosting generates a divergent sequence. The statistical interpretation suggest combining algorithm with an appropriate stopping rule for the iterative procedure. Finally we illustrate the practical finite sample performances of the iterative smoother via a simulation study.

  4. Reducing hypothetical bias in choice experiments

    DEFF Research Database (Denmark)

    Ladenburg, Jacob; Olsen, Søren Bøye; Nielsen, Rasmus Christian Fejer

    eliminate some of the hypothetical bias. The present paper tests an addition to Cheap Talk, an Opt-Out Reminder. The Opt-Out Reminder is an objective short script presented prior to the choice sets, prompting the respondent to choose the opt-out alternative, if he/she finds the proposed policy generated...... alternatives in a choice set too expensive. The results suggest that adding an Opt-Out Reminder to Cheap Talk can in fact reduce hypothetical bias even further and reduces some of the ineffectiveness of CT in relation to the survey bid range and experienced respondents....

  5. Integrated Foreign Exchange Risk Management

    DEFF Research Database (Denmark)

    Aabo, Tom; Høg, Esben; Kuhn, Jochen

    Empirical research has focused on export as a proxy for the exchange rate exposure and the use of foreign exchange derivatives as the instrument to deal with this exposure. This empirical study applies an integrated foreign exchange risk management approach with a particular focus on the role...... of import in medium-sized, manufacturing firms in Denmark (a small, open economy). We find a strong, negative relation between import and foreign exchange derivatives usage on the aggregate level. Our findings are consistent with the notion that firms use import to match the foreign exchange exposure...

  6. Integrated foreign exchange risk management

    DEFF Research Database (Denmark)

    Aabo, Tom; Høg, Esben; Kuhn, Jochen

    2010-01-01

    Empirical research has focused on export as a proxy for exchange rate exposure and the use of foreign exchange derivatives as an instrument to deal with this exposure. This empirical study applies an integrated foreign exchange risk management approach with a particular focus on the role of import...... in medium-sized manufacturing firms in Denmark (a small, open economy). We find a strong, negative relation between import and the use of foreign exchange derivatives on the aggregate level. Our findings are consistent with the notion that firms use import to match the foreign exchange exposure created...

  7. Mastering Microsoft Exchange Server 2010

    CERN Document Server

    McBee, Jim

    2010-01-01

    A top-selling guide to Exchange Server-now fully updated for Exchange Server 2010. Keep your Microsoft messaging system up to date and protected with the very newest version, Exchange Server 2010, and this comprehensive guide. Whether you're upgrading from Exchange Server 2007 SP1 or earlier, installing for the first time, or migrating from another system, this step-by-step guide provides the hands-on instruction, practical application, and real-world advice you need.: Explains Microsoft Exchange Server 2010, the latest release of Microsoft's messaging system that protects against spam and vir

  8. Temperature and cooling field dependent exchange coupling in [Cr/Gd]{sub 5} multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Jiao, Z.W.; Chen, H.J.; Jiang, W.D.; Wang, J.F.; Yu, S.J. [Department of Physics, China Jiliang University, Hangzhou (China); Hou, Y.L.; Lu, B.; Ye, Q.L. [Department of Physics, Hangzhou Normal University, Hangzhou (China)

    2016-09-15

    Exchange coupling has been investigated in the [Cr/Gd]{sub 5} multilayers deposited at 25, 200, and 400 C, where the Neel temperature (T{sub N}) of antiferromagnetic Cr is slightly higher than the Curie temperature (T{sub C}) of ferromagnetic Gd. It was found that the exchange coupling existed not only at T{sub C} < T < T{sub N}, but also above the temperature (T{sub N}) of antiferromagnetic orderings with incommensurate spin-density wave structures transiting to paramagnetic state. These results can be discussed in terms of the crucial role played by the antiferromagnetic spins of Cr with commensurate spin-density wave structures in the vicinity of the Cr/Gd interfaces. Moreover, the exchange coupling of the multilayers grown at different temperatures exhibited different dependencies on the measuring temperature and the cooling field, respectively. Positive exchange bias was observed in the multilayers grown at 200 and 400 C. The interfacial roughness, grain size, and the antiferromagnetic orderings of Cr may be responsible for the anomalous exchange coupling of the multilayers. In addition, the competition between the exchange coupling at Cr/Gd interfaces and the external field-Cr surface magnetic coupling can explain the appearance of negative or positive exchange bias. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Progress in liquid ion exchangers

    International Nuclear Information System (INIS)

    Nakagawa, Genkichi

    1974-01-01

    Review is made on the extraction with anion exchangers and the extraction with liquid cation exchangers. On the former, explanation is made on the extraction of acids, the relation between anion exchange and the extraction of metals, the composition of the metallic complexes that are extracted, and the application of the extraction with anion exchangers to analytical chemistry. On the latter, explanation is made on the extraction of metals and its application to analytical chemistry. The extraction with liquid ion exchangers is suitable for the operation in chromatography, because the distribution of extracting agents into aqueous phase is small, and extraction equilibrium is quickly reached, usually within 1 to several minutes. The separation by means of anion exchangers is usually made from hydrochloric acid solution. For example, Brinkman et al. determined Rf values for more than 50 elements by thin layer chromatography. Tables are given for showing the structure of the liquid ion exchangers and the polymerized state of various amines. (Mori, K.)

  10. Vowels, then consonants: Early bias switch in recognizing segmented word forms.

    Science.gov (United States)

    Nishibayashi, Léo-Lyuki; Nazzi, Thierry

    2016-10-01

    The division of labor hypothesis proposed by Nespor, Peña, and Mehler (2003) postulates that consonants are more important than vowels in lexical processing (when learning and recognizing words). This consonant bias (C-bias) is supported by many adult and toddler studies. However, some cross-linguistic variation has been found in toddlerhood, and various hypotheses have been proposed to account for the origin of the consonant bias, which make distinct predictions regarding its developmental trajectory during the first year of life. The present study evaluated these hypotheses by investigating the consonant bias in young French-learning infants, a language in which a consistent consonant bias is reported from 11months of age onward. Accordingly, in a series of word form segmentation experiments building on the fact that both 6- and 8-month-old French-learning infants can segment monosyllabic words, we investigated the relative impact of consonant and vowel mispronunciations on the recognition of segmented word forms at these two ages. Infants were familiarized with passages containing monosyllabic target words and then tested in different conditions all including consonant and/or vowel mispronunciations of the target words. Overall, our findings reveal a consonant bias at 8months, but an opposite vowel bias at 6months. These findings first establish that the consonant bias emerges between 6 and 8months of age in French-learning infants. Second, we discuss the factors that might explain such a developmental trajectory, highlighting the possible roles of pre-lexical and phonological acquisition. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Physicochemical basis of the ion-exchange separation of gold cyanide complexes

    Science.gov (United States)

    Kononova, O. N.; Kononov, Yu. S.

    2014-10-01

    The mechanism of the separation of gold cyanide complexes is discussed, along with ion exchanger selection, selectivity, elution, and industrial applications. The ion-exchange mechanism for the sorption of gold cyanide complexes is established, and a criterion is suggested for selecting the anion exchanger for their extraction (specifically, the p K a of the anion exchanger). The selectivity of the sorption of gold cyanide complexes by anion exchangers with rarely distributed ionogenic groups is demonstrated. A procedure for the elution of gold cyanide complexes using alkaline solutions is developed.

  12. Basic MR sequence parameters systematically bias automated brain volume estimation

    International Nuclear Information System (INIS)

    Haller, Sven; Falkovskiy, Pavel; Roche, Alexis; Marechal, Benedicte; Meuli, Reto; Thiran, Jean-Philippe; Krueger, Gunnar; Lovblad, Karl-Olof; Kober, Tobias

    2016-01-01

    Automated brain MRI morphometry, including hippocampal volumetry for Alzheimer disease, is increasingly recognized as a biomarker. Consequently, a rapidly increasing number of software tools have become available. We tested whether modifications of simple MR protocol parameters typically used in clinical routine systematically bias automated brain MRI segmentation results. The study was approved by the local ethical committee and included 20 consecutive patients (13 females, mean age 75.8 ± 13.8 years) undergoing clinical brain MRI at 1.5 T for workup of cognitive decline. We compared three 3D T1 magnetization prepared rapid gradient echo (MPRAGE) sequences with the following parameter settings: ADNI-2 1.2 mm iso-voxel, no image filtering, LOCAL- 1.0 mm iso-voxel no image filtering, LOCAL+ 1.0 mm iso-voxel with image edge enhancement. Brain segmentation was performed by two different and established analysis tools, FreeSurfer and MorphoBox, using standard parameters. Spatial resolution (1.0 versus 1.2 mm iso-voxel) and modification in contrast resulted in relative estimated volume difference of up to 4.28 % (p < 0.001) in cortical gray matter and 4.16 % (p < 0.01) in hippocampus. Image data filtering resulted in estimated volume difference of up to 5.48 % (p < 0.05) in cortical gray matter. A simple change of MR parameters, notably spatial resolution, contrast, and filtering, may systematically bias results of automated brain MRI morphometry of up to 4-5 %. This is in the same range as early disease-related brain volume alterations, for example, in Alzheimer disease. Automated brain segmentation software packages should therefore require strict MR parameter selection or include compensatory algorithms to avoid MR parameter-related bias of brain morphometry results. (orig.)

  13. Basic MR sequence parameters systematically bias automated brain volume estimation

    Energy Technology Data Exchange (ETDEWEB)

    Haller, Sven [University of Geneva, Faculty of Medicine, Geneva (Switzerland); Affidea Centre de Diagnostique Radiologique de Carouge CDRC, Geneva (Switzerland); Falkovskiy, Pavel; Roche, Alexis; Marechal, Benedicte [Siemens Healthcare HC CEMEA SUI DI BM PI, Advanced Clinical Imaging Technology, Lausanne (Switzerland); University Hospital (CHUV), Department of Radiology, Lausanne (Switzerland); Meuli, Reto [University Hospital (CHUV), Department of Radiology, Lausanne (Switzerland); Thiran, Jean-Philippe [LTS5, Ecole Polytechnique Federale de Lausanne, Lausanne (Switzerland); Krueger, Gunnar [Siemens Medical Solutions USA, Inc., Boston, MA (United States); Lovblad, Karl-Olof [University of Geneva, Faculty of Medicine, Geneva (Switzerland); University Hospitals of Geneva, Geneva (Switzerland); Kober, Tobias [Siemens Healthcare HC CEMEA SUI DI BM PI, Advanced Clinical Imaging Technology, Lausanne (Switzerland); LTS5, Ecole Polytechnique Federale de Lausanne, Lausanne (Switzerland)

    2016-11-15

    Automated brain MRI morphometry, including hippocampal volumetry for Alzheimer disease, is increasingly recognized as a biomarker. Consequently, a rapidly increasing number of software tools have become available. We tested whether modifications of simple MR protocol parameters typically used in clinical routine systematically bias automated brain MRI segmentation results. The study was approved by the local ethical committee and included 20 consecutive patients (13 females, mean age 75.8 ± 13.8 years) undergoing clinical brain MRI at 1.5 T for workup of cognitive decline. We compared three 3D T1 magnetization prepared rapid gradient echo (MPRAGE) sequences with the following parameter settings: ADNI-2 1.2 mm iso-voxel, no image filtering, LOCAL- 1.0 mm iso-voxel no image filtering, LOCAL+ 1.0 mm iso-voxel with image edge enhancement. Brain segmentation was performed by two different and established analysis tools, FreeSurfer and MorphoBox, using standard parameters. Spatial resolution (1.0 versus 1.2 mm iso-voxel) and modification in contrast resulted in relative estimated volume difference of up to 4.28 % (p < 0.001) in cortical gray matter and 4.16 % (p < 0.01) in hippocampus. Image data filtering resulted in estimated volume difference of up to 5.48 % (p < 0.05) in cortical gray matter. A simple change of MR parameters, notably spatial resolution, contrast, and filtering, may systematically bias results of automated brain MRI morphometry of up to 4-5 %. This is in the same range as early disease-related brain volume alterations, for example, in Alzheimer disease. Automated brain segmentation software packages should therefore require strict MR parameter selection or include compensatory algorithms to avoid MR parameter-related bias of brain morphometry results. (orig.)

  14. Interface exchange parameters in La{sub 2/3}Ca{sub 1/3}Mn{sub 3}O/La{sub 1/3}Ca{sub 2/3}Mn{sub 3}O bilayers: a Monte Carlo approach

    Energy Technology Data Exchange (ETDEWEB)

    Restrepo-Parra, E., E-mail: erestrepopa@unal.edu.co [Universidad Nacional de Colombia-Sede Manizales, PCM Computational Applications, Manizales (Colombia); Londoño-Navarro, J. [Universidad Nacional de Colombia-Sede Manizales, PCM Computational Applications, Manizales (Colombia); Restrepo, J. [Grupo de Magnetismo y Simulación. Instituto de Física. Universidad de Antioquia. A.A. 1226, Medellín (Colombia)

    2013-10-15

    Ferromagnetic/antiferromagnetic (FM/AF) bilayers have been widely studied because they exhibit special phenomena, such as exchange bias and magnetoresistance. These effects are strongly influenced by interface behavior. In this work, a study of hysteresis loops in La{sub 2/3}Ca{sub 1/3}MnO{sub 3}/La{sub 1/3}Ca{sub 2/3}MnO{sub 3} bilayers is presented. Simulations were carried out using the Monte Carlo method combined with the Metropolis algorithm and Heisenberg model. The study was focused on determining the most suitable exchange parameters at the interface by applying the model proposed by Kiwi. This model considers the use of two interface exchange parameters to represent the anisotropy that occurs at the interface because of the contact between two phases (ferromagnetic and antiferromagnetic). These two interface exchange parameters were named J{sub I1} and J{sub I2}. Initially, we assumed J{sub I1} to be equal to J{sub I2} without presenting exchange bias. Then, J{sub I1} and J{sub I2} were assumed to be different. In this configuration, the exchange phenomenon appeared in the hysteresis loops. It was also observed that the exchange bias is strongly dependent on the ratio of J{sub I1} to J{sub I2}. As J{sub I1} increases, the exchange bias decreases slowly and becomes comparable to the effective exchange bias field, assuming that it only depends on ΔJ{sub I}=J{sub I1}−J{sub I2}. - Highlights: • Exchange bias is influenced by the type of interaction ions and exchange parameters. • An interface asymmetric is required for observing the exchange bias phenomenon. • Monte Carlo method allows simulating the exchange bias phenomenon in FM/AF systems.

  15. Faculty-Exchange Programs Promoting Change: Motivations, Experiences, and Influence of Participants in the Carnegie Mellon University-Portugal Faculty Exchange Program

    Science.gov (United States)

    Patrício, Maria Teresa; Santos, Patrícia; Loureiro, Paulo Maia; Horta, Hugo

    2018-01-01

    The international mobility of faculty is increasing worldwide. Although studies have considered the experiences of academics abroad, less is known about faculty-exchange programs with policy objectives. This study helps to fill this gap by analyzing a nationwide structured faculty exchange program established by Carnegie Mellon University and…

  16. 76 FR 69788 - Self-Regulatory Organizations; New York Stock Exchange LLC; Notice of Filing of Rule Change...

    Science.gov (United States)

    2011-11-09

    ... Proposed Rule Change The Exchange proposes a one-year pilot program that would add new Rule 107C to.... Purpose The Exchange is proposing a one-year pilot program that would add new NYSE Rule 107C to establish...-Regulatory Organizations; New York Stock Exchange LLC; Notice of Filing of Rule Change Proposing a One-Year...

  17. Referral bias in ALS epidemiological studies.

    Science.gov (United States)

    Logroscino, Giancarlo; Marin, Benoit; Piccininni, Marco; Arcuti, Simona; Chiò, Adriano; Hardiman, Orla; Rooney, James; Zoccolella, Stefano; Couratier, Philippe; Preux, Pierre-Marie; Beghi, Ettore

    2018-01-01

    Despite concerns about the representativeness of patients from ALS tertiary centers as compared to the ALS general population, the extent of referral bias in clinical studies remains largely unknown. Using data from EURALS consortium we aimed to assess nature, extent and impact of referral bias. Four European ALS population-based registries located in Ireland, Piedmont, Puglia, Italy, and Limousin, France, covering 50 million person-years, participated. Demographic and clinic characteristics of ALS patients diagnosed in tertiary referral centers were contrasted with the whole ALS populations enrolled in registries in the same geographical areas. Patients referred to ALS centers were younger (with difference ranging from 1.1 years to 2.4 years), less likely to present a bulbar onset, with a higher proportion of familial antecedents and a longer survival (ranging from 11% to 15%) when compared to the entire ALS population in the same geographic area. A trend for referral bias is present in cohorts drawn from ALS referral centers. The magnitude of the possible referral bias in a particular tertiary center can be estimated through a comparison with ALS patients drawn from registry in the same geographic area. Studies based on clinical cohorts should be cautiously interpreted. The presence of a registry in the same area may improve the complete ascertainment in the referral center.

  18. Knowledge of Social Affiliations Biases Economic Decisions.

    Science.gov (United States)

    Martinez, Joel E; Mack, Michael L; Gelman, Bernard D; Preston, Alison R

    2016-01-01

    An individual's reputation and group membership can produce automatic judgments and behaviors toward that individual. Whether an individual's social reputation impacts interactions with affiliates has yet to be demonstrated. We tested the hypothesis that during initial encounters with others, existing knowledge of their social network guides behavior toward them. Participants learned reputations (cooperate, defect, or equal mix) for virtual players through an iterated economic game (EG). Then, participants learned one novel friend for each player. The critical question was how participants treated the friends in a single-shot EG after the friend-learning phase. Participants tended to cooperate with friends of cooperators and defect on friends of defectors, indicative of a decision making bias based on memory for social affiliations. Interestingly, participants' explicit predictions of the friends' future behavior showed no such bias. Moreover, the bias to defect on friends of defectors was enhanced when affiliations were learned in a social context; participants who learned to associate novel faces with player faces during reinforcement learning did not show reputation-based bias for associates of defectors during single-shot EG. These data indicate that when faced with risky social decisions, memories of social connections influence behavior implicitly.

  19. Biased Allocation of Faces to Social Categories

    NARCIS (Netherlands)

    Dotsch, R.; Wigboldus, D.H.J.; Knippenberg, A.F.M. van

    2011-01-01

    Three studies show that social categorization is biased at the level of category allocation. In all studies, participants categorized faces. In Studies 1 and 2, participants overallocated faces with criminal features-a stereotypical negative trait-to the stigmatized Moroccan category, especially if

  20. Economic Costs of Bias-Based Bullying

    Science.gov (United States)

    Baams, Laura; Talmage, Craig A.; Russell, Stephen T.

    2017-01-01

    Because many school districts receive funding based on student attendance, absenteeism results in a high cost for the public education system. This study shows the direct links between bias-based bullying, school absenteeism because of feeling unsafe at school, and loss of funds for school districts in California. Data from the 2011-2013…